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Riyadh, Saudi Arabia

King Saud University is a public university located in Riyadh, Saudi Arabia. It was founded in 1957 by King Saud bin Abdul Aziz as Riyadh University, as the first university in the kingdom not dedicated to religious subjects. The university was created to meet the shortage of skilled workers in Saudi Arabia. It was renamed to King Saud University in 1982. The student body of KSU today consists of about 37,874 students of both sexes. Wikipedia.


Alotaibi K.D.,University of Saskatchewan | Alotaibi K.D.,King Saud University | Schoenau J.J.,University of Saskatchewan
Biology and Fertility of Soils | Year: 2013

Ethanol production results in distiller grain, and biodiesel produces glycerol as by-product. However, there is limited information on effects of their addition on evolution of N2O and CO2 from soils, yet it is important to enable our understanding of impacts of biofuel production on greenhouse gas budgets. The objective of this study was to evaluate the direct effects of adding wet distillers grain (WDG), thin stillage (TS), and glycerol at three rates on greenhouse gas emissions (N2O and CO2) and nutrient supply rates in a cultivated soil from the Canadian prairies. The WDG and TS application rates were: 100, 200, or 400 kg N ha-1, whereas glycerol was applied at: 40, 400, or 4,000 kg C ha-1 applied alone (G - N) or in a combination with 300 kg N ha-1 (G + N). In addition, conventional amendments of urea (UR) and dehydrated alfalfa (DA) were added at the same rates of total N as the by-products for comparative purposes. The production of N2O and CO2 was measured over an incubation period of 10 days in incubation chambers and Plant Root Simulator™ resin membrane probes were used to measure nutrient (NH4 +-N, NO3 --N, and PO4 -3-P) supply rates in the soil during incubation. Per unit of N added, urea tended to result in the greatest N2O production, followed by wet distillers grain and thin stillage, with glycerol and dehydrated alfalfa resulting in the lowest N2O production. Cumulative N2O production increased with increasing the rate of N-containing amendments and was the highest at the high rate of UR treatment. Addition of urea with glycerol contributed to a higher rate of N2O emission, especially at the low rate of glycerol. The DA and WDG resulted in the greatest evolution of CO2 from the soil, with the thin stillage resulting in less CO2 evolved per unit of N added. Addition of N fertilizer along with glycerol enhanced microbial activity and decomposition. The amendments had significant impacts on release of available nutrient, with the UR treatments providing the highest NO3 --N supply rate. The TS treatments supplied the highest rate of NH4 +-N, followed by WDG compared to the other amendments. The WDG treatments were able to provide the greatest supply of PO4 -3-P supply in comparison to the other amendments. Microbial N immobilization was associated with glycerol treatments applied alone. This study showed that the investigated biofuel by-products can be suitable soil amendments as a result of their ability to supply nutrients and N2O emissions that did not exceed that of the conventional urea fertilizer. © 2012 Springer-Verlag. Source


The creation of the normal web spaces has been attributed to apoptosis. This paper presents evidence that lysosomal-mediated cell death and extracellular matrix degradation are important events in addition to cell death by apoptosis. The author proposes the use of the term interdigital cell death- extracellular matrix degradation instead of interdigital apoptosis . Furthermore, the concept of web creation by differential growth is introduced along with the discussion of the latest research in molecular biology and genetics on the topic. © The Author(s) 2013. Source


This study was carried out to explore the effect of DNA hypomethylation on chondrocytes phenotype, in particular the effect on chondrocyte hypertrophy, maturation, and apoptosis. Chondrocytes derived from caudal region of day 17 embryonic chick sterna were pretreated with hypomethylating drug 5-aza-2'-deoxycytidine for 48 hours and then maintained in the normal culture medium for up to 14 days. Histological studies showed distinct morphological changes occurred in the pretreated cultures when compared to the control cultures. The pretreated chondrocytes after 7 days in culture became bigger in size and acquired more flattened fibroblastic phenotype as well as a loss of cartilage specific extracellular matrix. Scanning electron microscopy at day 7 showed chondrocytes to have increased in cell volume and at day 14 in culture the extracellular matrix of the pretreated cultures showed regular fibrillar structure heavily embedded with matrix vesicles, which is the characteristic feature of chondrocyte hypertrophy. Transmission electron microscopic studies indicated the terminal fate of the hypertrophic cells in culture. The pretreated chondrocytes grown for 14 days in culture showed two types of cells: dark cells which had condense chromatin in dark patches and dark cytoplasm. The other light chondrocytes appeared to be heavily loaded with endoplasmic reticulum indicative of very active protein and secretory activity; their cytoplasm had large vacuoles and disintegrating cytoplasm. The biosynthetic profile showed that the pretreated cultures were actively synthesizing and secreting type X collagen and alkaline phosphatase as a major biosynthetic product. © 2016. Anatomy & Cell Biology. Source


Morsy M.H.,King Saud University
Renewable and Sustainable Energy Reviews | Year: 2012

Performance of future ignition system for internal combustion engines should be reliable and efficient to enhance and sustain combustion stability, since ignition not only initiates combustion but also influences subsequent combustion. Lean burn systems have been regarded as an advanced combustion approach that could improve thermal efficiency while reducing exhaust gas emissions. However, current engines cannot be operated sufficiently lean due to ignition related problems such as the sluggish flame initiation and propagation along with potential misfiring. A high exhaust gas recirculation engines also has similar potential for emissions improvement, but could also experience similar ignition problems, particularly at idle operation. Similarly, ignition is an important design factor in gas turbine and rocket combustor. Recently, non-conventional ignition techniques such as laser-induced ignition methods have become an attractive field of research in order to replace the conventional spark ignition systems. The fundamentals of conventional laser-induced spark ignition have been previously reviewed. Therefore, the objective of this article is to review progress on the use of such innovative techniques of laser-induced ignition including laser-induced cavity ignition and laser-induced multi-point ignition. In addition, emphasis is given to recent work to explore the feasibility of this interesting technology for practical applications concerning internal combustion engines. © 2012 Elsevier Ltd. All rights reserved. Source


Abdel-Halim E.S.,King Saud University | Abdel-Halim E.S.,National Research Center of Egypt
Carbohydrate Polymers | Year: 2012

Cotton fabric was bleached in a simple and economic process using a bleaching system composed of sodium chlorite and hexamethylenetetramine. Different bleaching trials were carried out keeping fixed sodium chlorite concentration and varying other reaction conditions. The obtained results reveal that bleached cotton fabric with satisfactory whiteness index and reasonable tensile strength can be obtained by treating the fabric at 95°C in a bleaching bath containing 5 g/l sodium chlorite, 0.02 g/l hexamethylenetetramine and 1 g/l non-ionic wetting agent using a material to liquor ratio of 1:30. These optimum conditions lead to completion of the bleaching process in a reasonable duration of 2 h with minimum evolution of harmful chlorine dioxide gas. Lower concentrations of the activator hexamethylenetetramine were found to prolong the bleaching duration without getting satisfactory whiteness index. Higher concentrations of the activator were found to cause fast sodium chlorite decomposition without imparting bleaching effect to the fabric. © 2012 Elsevier Ltd. All rights reserved. Source


Abdel-Halim E.S.,King Saud University | Abdel-Halim E.S.,National Research Center of Egypt
Carbohydrate Polymers | Year: 2012

Surface characteristics of differently pretreated flax fibers have been studied using electrokinetic analysis (EKA) and inverse gas chromatography (IGC). Semi-retted and retted flax fibers were scoured and bleached conventionally. All pretreated flax fibers showed negative zeta-potential at all pH values, indicating an acidic fiber surface. The isoelectric point was not reached at pH 3 and can be estimated to be near a pH of 2 or even below, a value where the fibers will be damaged. Inverse gas chromatography measurements showed differences in the surface energy among the differently pretreated flax fibers irrespective of the relative humidity. The group of retted flax fibers in general was found to have higher surface energies than the corresponding semi-retted group. On the other hand, within the same flax fibers group (retted or semi-retted), it was found that the surface energy decreases in the order bleached fibers > scoured fibers > raw fibers. © 2012 Elsevier Ltd. All rights reserved. Source


Asif M.,King Saud University
International Journal of Mineral Processing | Year: 2010

The inverse fluidization of unequal solid species of a binary-pair leads to the occurrence of their stratification along the height of the bed. This phenomenon depends upon the difference in the physical properties and the relative composition of the individual species comprising the binary-pair besides the fluid velocity. Packing models are used here to account for the observed volume-contraction owing to the mixing of unequal solid species. In view of stability considerations, the minimum bulk density condition is used to predict the composition of the upper-layer located below the distributor. Predictions are consistent with the observed stratification pattern reported in the literature. © 2010 Elsevier B.V. All rights reserved. Source


Rotation osteotomy of the humerus has been described by several authors to treat the internal rotation contracture of the shoulder in Erb palsy. The main aim of the osteotomy in Erb patients is to bring the functioning hand to the face which greatly improves functi n. The author has performed the rotation humeral osteotomy in children with total obstetric brachial plexus palsy aiming for the improvement of the cosmetic appearance of the limb rather than improvement function. This article specifically reports on this group of patients.Over the last 15 years, the author has performed rotation humeral osteotomy in 13 children (mean age 6 years; range, 4.5-9 years) with total obstetric brachial plexus palsy aiming for improvement of the cosmetic appearance of the limb rather than improvement of function. All children had a triad of severe internal rotation contracture of the shoulder, severe flexion contracture of the elbow, and poor hand function.After a mean follow-up of 2 years following the humeral osteotomy, all patients/parents were satisfied with the result and a panel of plastic surgeons confirmed the significant improvement in aesthetics. Reasons for this improvement following the osteotomy were as follows: the child no longer needed to stand with shoulder slightly abducted, the antecubital fossa became visible in the standing position, and the forearm no longer appeared excessively pronated. Of more importance, was the improvement in elbow flexion contracture which had major contribution in improving limb appearance and the perception of length discrepancy between the affected and the contralateral normal limb.The humeral osteotomy improves the cosmetic appearance of children with total palsy and the triad of severe internal rotation contracture of the shoulder, severe flexion contracture of the elbow and poor hand function. Copyright © 2010 by Lippincott Williams & Wilkins. Source


Xu A.,University of Hong Kong | Vanhoutte P.M.,University of Hong Kong | Vanhoutte P.M.,King Saud University
American Journal of Physiology - Heart and Circulatory Physiology | Year: 2012

The heart and blood vessels are surrounded by epicardial and perivascular adipose tissues, respectively, which play important roles in maintaining cardiovascular homeostasis by secreting a number of biologically active molecules, termed "adipokines." Many of these adipokines function as an important component of the 'adipo-cardiovascular axis' mediating the cross talk between adipose tissues, the heart, and the vasculature. On the one hand, most adipokines [including tumor necrosis factor-α, resistin, adipocyte fatty acid binding protein (A-FABP), and lipocalin-2] are proinflammatory and causally associated with endothelial and cardiac dysfunction by their endocrine/paracrine actions. On the other hand, adiponectin is one of the few adipokines that possesses multiple salutary effects on the prevention of cardiovascular disease, because of its pleiotropic actions on the heart and the blood vessels. The discordant production of adipokines in dysfunctional adipose tissue is a key contributor to obesity-related cardiovascular disease. This review provides an update in understanding the roles of adipokines in the pathogenesis of cardiovascular disorders associated with obesity and diabetes and focuses on the two most abundant adipokines, adiponectin and A-FABP. Indeed, data from both animal studies and clinical investigations imply that these two adipokines are prognostic biomarkers for cardiovascular disease and even promising therapeutic targets for its treatment. © 2012 the American Physiological Society. Source


Attiya A.M.,King Saud University
IEEE Transactions on Antennas and Propagation | Year: 2011

Time-domain impulse transmission functions of a dispersive half space due to an obliquely incident pulsed plane wave of either TE or TM polarization are presented as inverse Fourier transforms. The frequency domain transmission functions are approximated by using Prony's method as finite series of exponential decaying functions. The inverse Fourier transform of these exponential decaying functions are evaluated analytically in closed forms. Time-domain response due to a specific pulse shape is obtained by convoluting the impulse transmission functions with the required pulse shape. © 2006 IEEE. Source


Abdel-Halim E.S.,King Saud University | Abdel-Halim E.S.,National Research Center of Egypt
Carbohydrate Polymers | Year: 2012

An effective sodium chlorite/potassium permanganate bleaching system was used to bleach cotton fabric without severe loss in the fabric's mechanical properties. The bleaching process based on depositing Mn III on the fabric surface followed by treating the fabric with sodium chlorite solution. Parameters governing the bleaching efficiency, like potassium permanganate concentration, sodium chlorite concentration and bleaching bath temperature were studied. The bleached fabrics were fully characterized by measuring their whiteness index, carboxyl and carbonyl contents, percent loss in fabric weight and tensile strength. The obtained results reveal that bleached cotton fabric with satisfactory whiteness index and reasonable tensile strength can be obtained by soaking the fabric, at 50 °C in potassium permanganate solution (0.01 N), using material to liquor ratio of 1:10. The fabric is then rinsed with distilled water, squeezed and introduced to bleaching bath containing 5 g/l sodium chlorite and 1 g/l non-ionic wetting agent using a material to liquor ratio of 1:10. © 2012 Elsevier Ltd. Source


Syed S.,King Saud University
Hydrometallurgy | Year: 2012

This paper presents an overview of the various methodologies used in the recovery of gold from secondary sources. Gold recovery is interesting due to its vast industrial applications, high market prices and extensively used precious metal, the sanctuary value attributed to gold during international political and economical crises, and the limited resource of this metal may explain the recent increasing gold share value. The state of art in recovery of gold from spent sources by pyrometallurgy; hydrometallurgy; bio-hydrometallurgy techniques is highlighted in this paper. This article also provides an overview of past achievements and present scenario of recovery studies carried out on the use of some promising methods which could serve as an economical means for recovering gold. The present review also highlights the used varieties of leaching, cementing, reducing agents, peeling, coagulants, adsorbents, agglomeration solvents, ion exchange resins and bio-sorbents in real situations and hopes to provide insights into recovery of gold from spent sources. Evaluation of lucrative and environmentally friendly technologies to recover gold from primary and secondary spent sources was made in this study. © 2011 Elsevier B.V. All rights reserved. Source


Alothman Z.A.,King Saud University
Materials | Year: 2012

Silicate mesoporous materials have received widespread interest because of their potential applications as supports for catalysis, separation, selective adsorption, novel functional materials, and use as hosts to confine guest molecules, due to their extremely high surface areas combined with large and uniform pore sizes. Over time a constant demand has developed for larger pores with well-defined pore structures. Silicate materials, with well-defined pore sizes of about 2.0-10.0 nm, surpass the pore-size constraint (<2.0 nm) of microporous zeolites. They also possess extremely high surface areas (>700 m2 g-1) and narrow pore size distributions. Instead of using small organic molecules as templating compounds, as in the case of zeolites, long chain surfactant molecules were employed as the structure-directing agent during the synthesis of these highly ordered materials. The structure, composition, and pore size of these materials can be tailored during synthesis by variation of the reactant stoichiometry, the nature of the surfactant molecule, the auxiliary chemicals, the reaction conditions, or by post-synthesis functionalization techniques. This review focuses mainly on a concise overview of silicate mesoporous materials together with their applications. Perusal of the review will enable researchers to obtain succinct information about microporous and mesoporous materials. © 2012 by the authors. Source


Romanos G.E.,State University of New York at Stony Brook | Javed F.,King Saud University
Journal of Oral Rehabilitation | Year: 2014

The aim was to assess the role of platform switching (PS) in minimising crestal bone loss around dental implants through a systematic review of the currently available clinical evidence. To address the focused question 'Does PS minimise crestal bone loss compared with non-platform-switched (NPS) implants?', PubMed/Medline and Google Scholar databases were explored from 1986 up to and including December 2013 using the following key words in different combinations: 'bone loss', 'dental implant', 'diameter', 'mandible', 'maxilla' and 'platform switching'. Letters to the Editor, unpublished data, historical reviews, case reports and articles published in languages other than English were excluded. Fifteen clinical studies were included. In seven studies, PS and NPS implants were placed in both the maxilla and mandible. In 13 studies, implants were placed at crestal bone levels whereas in one study, implants were placed supracrestally. Three studies reported the bucco-lingual (or transversal) width of the alveolar ridge which ranged between 7-8 mm. Seven studies reported that implants placed according to the PS concept did not minimise crestal bone loss as compared with NPS implants. 3D-Implant positioning, width of alveolar ridge and control of micromotion at the implant-abutment interface are the more critical factors that influence crestal bone levels than PS. © 2014 John Wiley & Sons Ltd. Source


Bin Muhaya F.T.,King Saud University
Security and Communication Networks | Year: 2015

The concept of Telecare medicine information systems (TMISs) has evolved to provide better health care to the masses. So the control of access to privileged services provided by TMIS is a crucial concern. Recently, Zhu proposed an authentication scheme for TMIS, which he claimed to be more suitable for TMIS environments than the scheme of Wei et al. especially regarding resistance to offline password guessing attack. However, this paper shows that Zhu's scheme still suffers from offline password guessing attack. We also show how an attacker can impersonate a legal user merely by intercepting a login request and how a legal user (patient) may often become victim of denial-of-service in crucial TMIS applications. We further show its vulnerability to online password guessing attack and smart card loss attack. To sort out these discrepancies from Zhu's scheme, we propose an improved scheme with session key establishment and user anonymity. Moreover, this improvement is achieved without adding any complex operation; even the communication cost of the proposed scheme is lesser than that in Zhu's scheme. Analysis shows the robustness as well as the simplicity of the proposed scheme. © 2014 John Wiley & Sons, Ltd. Source


Syed S.,King Saud University
Materials and Corrosion | Year: 2010

Atmospheric corrosion tests, according to ASTM G50-76, have been carried out in Saudi Arabia, at eight marine sites representing different environmental conditions. Environmental factors such as average temperature, average relative humidity, and deposition rates of atmospheric pollutants (Cl- and SO2) was investigated. X-ray diffraction has been used to determine the composition of the corrosion products. Corrosion rates have been determined for each sample at each of the exposure sites via loss of weight. The obtained data were used for the classification of atmospheric aggressivity, according to ISO 9223. The results obeyed well with the empirical kinetics equation of the form C=Ktn, where K and C are the corrosion losses in mg/cm 2 after 1 and t years of the exposure respectively, and n is constant. Based on n values, the corrosion mechanism of carbon steel is predicted. The major constituent of the rust formed in marine environment is goethite (α-FeOOH). Samples also show the presence of a large proportion of lepidocrocite (γ-FeOOH) and small amounts of ferrihydrite and maghemite (α-Fe203). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Purpose: To quantify the influence of soft contact lens power and thickness on the intraocular pressure (IOP). Methods: Thirty-nine young, healthy adult volunteers completed this study. One eye of each subject was randomly assigned either a +6D or a -6D high water content daily disposable lens. The other eye was fitted with the second lens. Triplicate measurements of IOP were taken before, during, and after contact lens wear. Each time, IOP was assessed in a randomized order with two noncontact tonometers. The lenses were swapped between eyes during a second session of measurements, one week later. Results: In the first session with the +6D lenses, the average IOPs (±SDs) before, with the lenses fitted, and after the lenses were removed, were: 14.3 ± 2.9. mmHg, 17.0 ± 3.3. mmHg and 13.9 ± 3.1. mmHg, respectively, for the CT80 and 13.6 ± 3.1. mmHg, 17.1 ± 4.5. mmHg and 13.3 ± 2.9. mmHg, respectively, for the PT100. The corresponding values for the first session with the -6D lenses were: 14.3 ± 3.1. mmHg, 13.1 ± 3.1. mmHg and 14.1 ± 3.3. mmHg, respectively, for the CT80 and 13.6 ± 3.2. mmHg, 13.0 ± 3.0. mmHg and 13.6 ± 3.2. mmHg, respectively, for the PT100. IOP significantly (P<0.05) increased (+ΔIOP = 2.7 ± 0.4. mmHg with the CT80 in the first session) with the +6D lenses, but decreased (P<0.05) when the -6D lenses were fitted (-ΔIOP = 0.6 ± 0.2. mmHg with the PT100 in the first session). The soft contact lens-induced changes were consistent between sessions but varied between tonometers. Conclusions: The measurement of IOP through soft contact lenses resulted in consistent, statistically significant differences in IOP, which were not uniform across tonometers and which did not appear to be solely related to the central thickness of the soft contact lenses. © 2012 British Contact Lens Association. Source


Al-Qattan M.M.,King Saud University
Journal of Hand Surgery: European Volume | Year: 2014

This review aims to highlight the differences in the management of flexor tendon injuries between children and adults. These include differences in epidemiology, anatomy, classification, diagnosis, incisions and skin closure, the size of the flexor tendons, technical aspects of zones I and II repairs, core suture purchase length, rehabilitation, results, and complications of primary flexor tendon repair. Finally, one-versus two-stage flexor tendon reconstruction in children is reviewed. © The Author(s) 2013. Source


Alhaqwi A.I.,King Saud University
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation, Saudi Arabia | Year: 2012

Feedback is an essential element in the process of students' learning and development. This study aimed to explore the views of medical students regarding the importance and process of feedback in their medical education. A cross-sectional questionnaire-based study was conducted in our college of medicine. The questionnaire included questions to assess the students' views about the importance and the need of feedback in the learning process and whether feed-back should follow certain or all forms of assessment. In addition, the questionnaire contained questions that aimed to explore students' views about the contents and process of feedback. One hundred and eighty-six male medical students participated in this study. While the majority of students (85%) indicated that feedback was important for their learning and expressed their need for regular feedback during their study, only about 20% of them indicated receiving regular feed-back. Senior students perceived that they received feedback less frequently than their junior colleagues' (P <0.05). The majority of the participants expressed their interest into receiving an immediate feedback after their summative and formative assessment. Students think that feedback should be balanced and include a suggested plan for their future learning process. Senior students showed a higher preference to have feedback that also contained points related to their strengths more than juniors. Students also indicated their preference to have one-to-one and written feed-back more than feedback that was conveyed in groups and verbally. These issues are of high importance and should be considered for planning and implementing an effective feedback system. Source


Abdel-Halim E.S.,King Saud University | Abdel-Halim E.S.,National Research Center of Egypt
Carbohydrate Polymers | Year: 2013

In this paper triethanolamine salt-catalyzed sodium chlorite bleaching system was used to bleach plain weave cotton fabric in one step. Different triethanolamine salts, including those derived from organic acids and mineral acids were tried for activating sodium chlorite decomposition during the bleaching reaction. All bleaching trials were carried out keeping fixed sodium chlorite concentration. The concentration of triethanolamine hydrochloride, as an example for the triethanolamine salts was varied to show the effect of the activator concentration on the final fabric degree of whiteness. The optimum triethanolamine hydrochloride concentration, required for activating sodium chlorite decomposition was found to be 10 mmol/l and based on that, this concentration was applied for other organic and inorganic triethanolamine salts to show the effect of nature of the activator on the final degree of whiteness. The results showed that salts prepared using mineral acids have activation potential better than those prepared using organic acids. © 2013 Elsevier Ltd. All rights reserved. Source


Despite the many benefits of nanotechnology, some studies indicate that certain nanoparticles may cause adverse effects because of their small size and unique properties. The aim of the present study was to elucidate the period effects of intraperitoneal administration of different gold GNP sizes on the rat kidney tissue in vivo using fluorescence spectroscopy. The experimental rats were divided into control and six groups (G1A, G1B, G2A, G2B, G3A and G3B; G1: 20 nm; G2: 10 nm; G3: 50 nm; A: infusion of GNPs for 3 days; B: infusion of GNPs for 7 days). To investigate the period effects of GNPs 10, 20 and 50 nm on the kidney tissue of rats, 50 μl dose of GNPs (of concentration 0.1% Au) were intraperitonealy injected into rats for periods of 3 and 7 days to identify the toxicity and tissue distribution of GNPs in vivo using fluorescence measurements. GNPs of sizes 10 and 20 nm show spherical morphology with good particle size distribution dispersed in the solution while GNPs of size 50 nm have no spherical shape, but they have hexagonal shape. At the infusion period of 3 days, the fluorescence intensity of the 1st peaks increased for G1A and decreased for G2A and G3A compared with the control while the fluorescence intensity of the 2nd peaks decreased for G1A, G2A and G3A compared with the control. At the infusion period of 7 days, the fluorescence intensity of the 1st and 2nd peaks increased for G1B and G2B and sharply decreased for G3B compared with the control. At the infusion periods of 3 and 7 days, the fluorescence intensity of the 1st peaks increased for G1A, G1B and G2B and decreased for G2A, G3A and G3B compared with the control while the fluorescence intensity of the 2nd peaks decreased for G1A, G1B, G2A, G2B and G3A compared with the control. Fluorescence intensity of GNPs varied with the GNP size. The decrease in fluorescence intensity may be attributed to size, shape, number of GNPs, quenching of 50 nm GNPs, surface area of GNPs and slow clearance for GNPs of 10 and 20 nm through urine and bile from the kidney. Moreover, decreasing size may lead to an exponential increase in surface area relative to volume, thus making the GNPs surface more reactive on itself (aggregation) and to its surrounding environment (biological components). Size and shape of GNPs may be related to their useful characters and also plays a key role in toxicity. The alterations of accumulation in the kidney tissue, depending on GNP size, which may be mediated by dynamic protein binding and exchange. A better understanding of these mechanisms will improve drug delivery and period and dose estimation used in the risk assessment. © 2011 Academic Journals. Source


El-Ahmed A.,King Saud University
Journal of the Egyptian Society of Parasitology | Year: 2012

The European bee-eater (Merops apiaster) migrates through Saudi Arabia annually. A total of 25 individuals of this species were captured from three localities in Riyadh and Ta'if. Three species of chewing lice were identified from these birds and newly added to list of Saudi Arabia parasitic lice fauna from 160 lice individuals, Meromenopon meropis of suborder Amblycera, Brueelia apiastri and Meropoecus meropis of suborder Ischnocera. The characteristic feature, identification keys, data on the material examined, synonyms, photo, type and type locality are provide to each species. Source


Al Jabbari Y.S.,King Saud University
The International journal of oral & maxillofacial implants | Year: 2012

To evaluate the effect of functional cyclic loading on two retrieved abutment screws used with single implant supporting cement-retained porcelain-fused-to-metal crowns by characterizing the structure, properties, and biotribologic behavior after long-term use in vivo. Two abutment screws were retrieved from the same patient and same implant at two different times. An external hex implant was used to replace a missing central incisor. A traumatic incident occurred 9 months after insertion and displaced the implant palatally by bending the screw. A second, similar incident occurred 31 months after insertion. In both cases, the abutment screws were retrieved and subjected to thorough nondestructive and destructive testing. Light and scanning electron microscopic examinations revealed very minimal surface deterioration of the thread profile for the first screw (in service for 9 months) and demonstrated advanced metal adhesive wear in the form of galling for the second screw (in service for 31 months). The galling led to moderate thinning of the thread profile. Both screws were composed of Au-based alloy, where the microstructure of the matrix consisted of homogeneous equiaxed fine grains with two different second phase particles. It appears that the occurrence of adhesive wear on abutment screws in the form of galling is highly related to the length of in-service time in the mouth. This biotribologic behavior was inevitable and considered to be a normal consequence of long-term use in vivo. Metallurgic analysis indicated that both screws were identical in terms of composition and microstructure. Source


Kalantan H.,King Saud University
Saudi Journal of Ophthalmology | Year: 2012

Posterior polar cataract is a rare form of congenital cataract. It is usually inherited as an autosomal dominant disease, yet it can be sporadic. Five genes have been attributed to the formation of this disease. It is highly associated with complications during surgery, such as posterior capsule rupture and nucleus drop. The reason for this high complication rate is the strong adherence of the opacity to the weak posterior capsule. Different surgical strategies were described for the handling of this challenging entity, most of which emphasized the need for gentle maneuvering in dealing with these cases. It has a unique clinical appearance that should not be missed in order to anticipate, avoid, and minimize the impact of the complications associated with it. © 2012 Saudi Ophthalmological Society, King Saud University. Source


Lembessis V.E.,King Saud University | Babiker M.,University of York
Physical Review Letters | Year: 2013

We show that the normally weak optical quadrupole interaction in atoms is enhanced significantly when the atom interacts at near resonance with an optical vortex. In particular, the forces and torque acting on the atom are shown here to scale up with the square of the winding number l of the vortex. Because the integer l can be arranged to be large, this property allows for processes involving dipole-forbidden, but quadrupole-allowed, transitions in atoms, such as cesium and oxygen, to come into play. We show that the mechanical effects of vortex light on atoms involving translational and rotational motion as well as trapping should be significantly enhanced for quadrupole transitions and present novel features with useful implications for the emerging field of atomtronics. © 2013 American Physical Society. Source


Abdel-Halim E.S.,King Saud University | Abdel-Halim E.S.,National Research Center of Egypt
Carbohydrate Polymers | Year: 2012

Poly(acrylic acid) hydroxyethyl cellulose [poly(AA)-HEC] graft copolymer was prepared by polymerizing acrylic acid (AA) with hydroxyethyl cellulose (HEC) using potassium bromate/thiourea dioxide (KBrO3/TUD) as redox initiation system. The polymerization reaction was carried out under a variety of conditions including concentrations of AA, KBrO3 and TUD, material to liquor ratio and polymerization temperature. The polymerization reaction was monitored by withdrawing samples from the reaction medium and measuring the total conversion. The rheological properties of the poly(AA)-HEC graft copolymer were investigated. The total conversion and rheological properties of the graft copolymer depended on the ratio of KBrO3 to TUD and on acrylic acid concentration as well as temperature and material to liquor ratio. Optimum conditions of the graft copolymer preparation were 30 mmol KBrO3 and 30 mmol TUD/100 g HEC, 100% AA (based on weight of HEC), duration 2 h at temperature 50 °C using a material to liquor ratio of 1:10. © 2012 Elsevier Ltd. All rights reserved. Source


Sherif E.-S.M.,King Saud University | Sherif E.-S.M.,National Research Center of Egypt
Applied Surface Science | Year: 2014

The corrosion of high strength maraging steel after varied immersion times in concentrated solution, 2.0 M, of sulfuric acid has been investigated. The work was also extended to study the effect of 5-(3-aminophenyl)-tetrazole (APTA) on the inhibition of the steel corrosion. The study has been carried out using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscope (SEM) along with energy dispersive X-ray analyzer (EDX) investigations. EIS spectra showed that the corrosion and polarization resistances decrease with increasing the immersion time of the steel before measurement and increase in the presence of APTA and the increase of its concentration. Polarization data agreed with the EIS measurements and indicated that the increase of immersion time increases the corrosion of steel by increasing its corrosion current and corrosion rate and lowering its polarization resistance. On the other hand, the addition of APTA and the increase of its concentration minimized the corrosion of steel through decreasing the corrosion current and corrosion rate and increasing the polarization resistance at all exposure test periods. SEM and EDX investigations confirmed that the inhibition of the maraging steel in the 2.0 M H 2SO4 solutions is achieved via the adsorption of the APTA molecules onto the steel protecting its surface from being dissolved easily. © 2013 Elsevier B.V. Source


Tyrlis E.,The Cyprus Institute | Lelieveld J.,The Cyprus Institute | Lelieveld J.,Max Planck Institute for Chemistry | Lelieveld J.,King Saud University | Steil B.,Max Planck Institute for Chemistry
Climate Dynamics | Year: 2013

The summer circulation over the eastern Mediterranean and the Middle East (EMME) is dominated by persistent northerly winds (Etesians) whose ventilating effect counteracts the adiabatic warming induced by large scale subsidence. The ERA40 dataset is used to study the vertical distribution of these circulation features, which both appear to be reconciled manifestations of the South Asian monsoon influence. As predicted by past idealized modeling studies, in late spring a westward expanding upper level warm structure and subsidence areas are associated with Rossby waves excited by the monsoon convection. Steep sloping isentropes that develop over the EMME facilitate further subsidence on the western and northern periphery of the warm structure, which is exposed to the midlatitude westerlies. The northerly flow and descent over the eastern Mediterranean have maxima in July that are strikingly synchronous to the monsoon convection over northern India, where the weaker easterly jet favors a stronger Rossby wave response and consequent impact on the EMME circulation. The pronounced EMME topography modifies the monsoon induced structure, firstly, by inducing orographically locked summer anticyclones. These enhance the mid and low level northwesterly flow at their eastern flanks, leading to distinct subsidence maxima over the eastern Mediterranean and Iran. Secondly, topography amplifies the subsidence and the northerly flow over the Aegean, Red Sea, the Iraq-Gulf region and to the east of the Caspian Sea. © 2012 The Author(s). Source


Abdelhalim M.A.K.,King Saud University | Jarrar B.M.,Al Jouf University
Journal of Nanobiotechnology | Year: 2012

Background: Nanoparticles (NPs) can potentially cause adverse effects on organ, tissue, cellular, subcellular and protein levels due to their unusual physicochemical properties. Advances in nanotechnology have identified promising candidates for many biological and biomedical applications. Since the properties of NPs differ from that of their bulk materials, they are being increasingly exploited for medical uses and other industrial applications. The aim of the present study was to investigate the particle-size effect of gold nanoparticles (GNPs) on the hepatic tissue in an attempt to cover and understand the toxicity and the potential threat of their therapeutic and diagnostic use.Methods: To investigate particle-size effect of GNPs on the hepatic tissue, a total of 70 healthy male Wistar-Kyoto rats were exposed to GNPs received 50 or 100 ul of GNPs infusion of size (10, 20 and 50 nm for 3 or 7 days).Results: In comparison with respective control rats, exposure to GNPs doses has produced alterations in the hepatocytes, portal triads and the sinusoids. The alterations in the hepatocytes were mainly summarized as hydropic degeneration, cloudy swelling, fatty degeneration, portal and lobular infiltrate by chronic inflammatory cells and congestive dilated central veins.Conclusions: The induced histological alterations might be an indication of injured hepatocytes due to GNPs toxicity that became unable to deal with the accumulated residues resulting from metabolic and structural disturbances caused by these NPs. These alterations were size-dependent with smaller ones induced the most effects and related with time exposure of GNPs. The appearance of hepatocytes cytoplasmic degeneration and nuclear destruction may suggest that GNPs interact with proteins and enzymes of the hepatic tissue interfering with the antioxidant defense mechanism and leading to reactive oxygen species (ROS) generation which in turn may induce stress in the hepatocytes to undergo atrophy and necrosis. More histomorphologcal, histochemical and ultrastrucural investigations are needed in relation of the application of GNPs with their potential threat as a therapeutic and diagnostic tool. © 2012 Abdelhalim and Jarrar; licensee BioMed Central Ltd. Source


Albishi T.,Memorial University of Newfoundland | John J.A.,Memorial University of Newfoundland | Al-Khalifa A.S.,King Saud University | Shahidi F.,Memorial University of Newfoundland
Journal of Functional Foods | Year: 2013

The total content of free, esterified and bound phenolics of the peel and flesh of four potato varieties (Purple, Innovator, Russet and Yellow) were determined using the Folin-Ciocalteu method. The respective antioxidant activities of these potatoes and/or their skins were evaluated using several in vitro assays. The phenolic profiles of potato peel and flesh samples were determined using high-performance liquid chromatography with photodiode array detection (HPLC-DAD). Bound and esterified phenolics contributed as much or even more than the free phenolics to the antioxidant activity of the peels; extracts from Purple variety showing the highest activity. The peels of all varieties showed significantly (p<0.05) higher phenolic content and antioxidant activities than their respective flesh. Chromatographic data showed differences in the amounts, but not in types, of phenolic compounds in the potato peel samples. Thus, potato processing discard may be used in food formulations and their extracts could potentially be employed as an effective source of antioxidants in food systems. © 2013 Elsevier Ltd. Source


Al-Ayadhi L.Y.,King Saud University
Behavioral and brain functions : BBF | Year: 2012

We examined whether plasma concentrations of amyloid beta (Aβ) as protein derivatives play a central role in the etiology of autistic features. Concentrations of human Aβ (1-42), Aβ (1-40), and Aβ (40/42) in the plasma of 52 autistic children (aged 3-16 years) and 36 age-matched control subjects were determined by using the ELISA technique and were compared. Compared to control subjects, autistic children exhibited significantly lower concentrations of both Aβ (1-40) and Aβ (1-42) and lower Aβ (40/42) concentration ratio. Receiver operating characteristics curve (ROC) analysis showed that these measurements of Aβ peptides showed high specificity and sensitivity in distinguishing autistic children from control subjects. Lower concentrations of Aβ (1-42) and Aβ (1-40) were attributed to loss of Aβ equilibrium between the brain and blood, an imbalance that may lead to failure to draw Aβ from the brain and/or impairment of β- and γ- secretase's concentration or kinetics as enzymes involving in Aβ production. Source


Bhushan R.,Indian Institute of Technology Roorkee | Bruckner H.,Justus Liebig University | Bruckner H.,King Saud University
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2011

The present paper describes an updated knowledge and status on Marfey's reagent (MR), 1-fluoro-2,4-dinitrophenyl-5-l-alanine amide (FDNP-l-Ala-NH2). The reagent is used for pre-column derivatization of amino acids followed by HPLC separation of the diastereomers so formed. Emphasis is put on the design and application of structural variants which are synthesized by introducing different (other than l-Ala-NH2) l- and d-amino acid amides and amino acids in the 1,5-difluoro-2,4-dinitro benzene (DFDNB) moiety, as the chiral auxiliary. Advantages, disadvantages, the required precautions and suitability of the approach for the separation of multi component mixtures of dl-amino acids are assessed. Use of two dimensional (2D) techniques, in particular online HPLC in combination with various mass spectrometry techniques is discussed as well as methods designated 'advanced Marfey's method' and 'C3 Marfey's method'. Application of MR and its variants for the determination of the stereochemistry of protein and non-protein amino acids in bioactive natural products isolated from living organisms (bacteria including blue-green algae, filamentous fungi, plants, marine sponges, invertebrates and vertebrates), in physiological samples including human beings, and in biologically relevant synthetic peptides are presented. In an outlook future applications are envisaged. © 2011 Elsevier B.V. Source


Background: Previous studies have reported conflicting survival rates for connective tissue disease (CTD)-associated usual interstitial pneumonia (UIP) and idiopathic pulmonary fibrosis (IPF/UIP). This study investigated the differences in the clinical characteristics and prognoses of patients diagnosed with CTD-UIP and IPF/UIP. Methods: A retrospective review of patients with IPF (n=88) and CTD-UIP (n=67) from January 2008 to June 2013 was completed. We compared the demographics and clinical characteristics between the two groups. Survival rates were compared using a log-rank and Cox proportional hazard regression analysis. Results: Undifferentiated-CTD (UCTD) accounted for 33% of the established CTD-UIP cases. No significant differences were identified in the demographic characteristics or physiological parameters between the UCTD and CTD patients (all P>0.05). However, the CTD-UIP patients were more likely to be young, female, and nonsmokers compared with the IPF/UIP group (all P<0.01). There was no difference in survival between the IPF/UIP and CTD-UIP patients [hazard ratio (HR), 1.74; 95% confidence interval (CI), 0.86-3.50; P=0.113]. However, the removal of the UCTD patients from the CTD group revealed that IPF/UIP was associated with a 2.47-fold increased risk of mortality compared with CTD-UIP (HR, 2.47; 95% CI, 1.01-6.09; P=0.049). Conclusions: Our findings indicate that the survival of CTD-UIP patients was similar compared with that of IPF/UIP patients. However, it appears that UCTD influences the survival rate of CTD-UIP patients. Source


Al-Qurainy F.,King Saud University
African Journal of Biotechnology | Year: 2010

As an influence of the Mediterranean diet, Eruca sativa (rocket salad) is eaten all over the world in salads and soups. It belongs to plant order Capparales (glucosinolate-containing species) and it is from the family Brassicaceae. Predominantly, the leaves of this species is eaten raw or cooked, although flowers are also consumed. Assessment of environmental contamination on ecology (plant) at molecular and population levels is important in risk quantification and remediation study. Heavy metal toxicity in plants is to induce oxidative stress linked to oxidation of proteins and membrane lipids but also to alterations of DNA damage response. E. sativa has been investigated in our study which is of agronomical importance and widely used in European countries. We studied three heavy metals Zn, Pb and Cd which showed a dose-dependent effect on radicle and coleoptile lengths of E. sativa. The radicle length was more affected than the coleoptiles length under all concentration tested plant. The ranking of genotoxic potencies in all three heavy metals was in the descending order: Cd2+ > Pb2+ ≥ Zn2+. Among these heavy metals, high concentration of Cd (150 mg/l) and Pb (150 mg/l) generated mutations along with changed morphology of seedlings. The radicle and coleoptile lengths (cm) under high concentration of Cd were decreased as compared to low, medium and high concentrations treated seedlings with Pb and Zn. 20 ISSR primers were used, of which four did not amplify, three gave single band and the rest of thirteen primers generated upto six bands (an average of 4 bands per primer). Sixteen primers exhibiting amplified products gave monomorphic; only two primers (OPC-5 and OPC-7) gave unique extra band in seedlings treated with medium and high concentrations of heavy metals Cd and Pb, respectively. The dendrogram was constructed to evaluate the genetic distance generated among the seedling treated with various heavy metals at various concentrations. The similarity matrix values were found from 42.8 to 100% and these values showed the genetic divergence among the seedlings treated with various concentrations of heavy metals. © 2010 Academic Journals. Source


Akhtar S.,King Saud University
Microscopy Research and Technique | Year: 2012

Introduction: The corneal tissue was processed in fixatives and embedded in resin for transmission electron microscopy to observe the ultrastructure of the collagen fibrils (CFs). The effect of these processing methods on the CF diameter and the interfibrillar spacing was studied. Methods: Four normal human corneal buttons were used for this study. A part of each cornea was fixed in 2.5% glutaraldehyde containing cuprolinic blue in sodium acetate buffer and embedded in spurr's resin (SpurrCB). A second part of each cornea was fixed in 2.5% glutaraldehyde + osmium tetroxide and embedded spurr's resin (SpurrOsm). The third part of each cornea was fixed in paraformaldehyde (4%) and embedded in LR White at 4°C (LRWhite). Ultrathin sections were stained with uranyl acetate and lead citrate. Results: In the tissue, fixed in SpurrCB, the diameter was 38.4 ± 5.9 nm and spacing between CF was 52.5 ± 5.3 nm. In the tissue fixed in SpurrOsm, the diameter was 28.37 ± 5.84 nm and spacing between CF was 45 ± 4.57 nm. In the tissue fixed in LR White, the CF diameter was 24 ± 2.3 nm and spacing between CF was 39.0 ± 4.2 nm. The diameters and interfibrillar spacing of the tissue processed by SpurrCB, SpurrOsm, and LRWhite were significantly different (P < 0.001) from one another. Conclusion: Our study shows that there is a variation in the CF diameter and spacing depending on the method of fixation and embedding resins used. This needs to be considered when comparative studies using different methods are done. © 2012 Wiley Periodicals, Inc. Source


A novel nano-composite cation exchanger sodium dodecyl sulfate acrylamide Zr(IV) selenite (SDS-AZS) was developed by sol-gel method. The physico-chemical properties of SDS-AZS were studied using FTIR, TGA, XRD, SEM, EDX, TEM and elemental analyses. The material was effectively used for the removal of Pb2+ which is an important environmental pollutant. Batch experiments were performed as a function of various experimental parameters such as effect of pH (2-10), contact time (5-60min), SDS-AZS dose (0.1-1.0g), initial Pb2+ concentration (10-30μgmL-1) and temperature (25-55°C). The uptake rate of Pb2+ onto SDS-AZS was rapid and equilibrium established within 40min. Kinetic studies showed better applicability for pseudo-first-order model. The applicability of Langmuir, Freundlich and Temkin isotherm models was investigated and the Freundlich isotherm exhibited the best fit with the experimental data. The values of thermodynamic parameters (δG°, δH° and δS°) were computed from the Van't Hoff plot which showed that the adsorption of Pb2+ was feasible, endothermic and spontaneous. The regeneration studies were carried out which demonstrated a decrease in the recovery of Pb2+ from 90% to 79% after four consecutive cycles. On the basis of good uptake capacity, SDS-AZS was successfully used for the removal and recovery Pb2+ from a real water sample spiked with Pb2+. © 2013 Elsevier B.V. Source


The etiology of autism spectrum disorders (ASD) is not well known but oxidative stress has been suggested to play a pathological role. We report here that the serum levels of Sonic hedgehog (SHH) protein and brain-derived neurotrophic factor (BDNF) might be linked to oxidative stress in ASD. By using the whole blood or polymorphonuclear leukocytes, we demonstrated that autistic children produced a significantly higher level of oxygen free radicals (OFR). In addition, we found significantly higher levels of serum SHH protein in children with mild as well as severe form of autism. We also found that the serum level of BDNF was significantly reduced in autistic children with mild form of the disorder but not with severe form of the disorder. Our findings are the first to report a correlation between SHH, BDNF and OFR in autistic children, suggesting a pathological role of oxidative stress and SHH in autism spectrum disorders. © 2011 The Author(s). Source


In this work, the results obtained from studying the anodic dissolution of pure iron and API X-65 5L pipeline steel after 40 min and 12 h exposure period in 4.0 wt % NaCl solutions at room temperature were reported. Potential- Time, electrochemical impedance spectroscopy, potentiodynamic polarization, and chronoamperometric current- Time at constant potential techniques were employed. It has been found that the iron electrode corrodes in the chloride test solutions faster than the API X-65 5L steel does under the same conditions. Increasing the exposure period for the electrodes from 40 min to 12 h showed a significant reduction in the corrosion parameters for both iron and steel in the 4.0 wt % NaCl solution. Results together confirmed clearly that the X-65 steel is superior to iron against corrosion in sodium chloride solutions. Source


Bousiakou Leda G.,King Saud University
Research Journal of Chemistry and Environment | Year: 2015

This work summarises current techniques in TiO2 energy band gap manipulation for photocatalytic purposes. It presents in a concise manner the ideas of energy band gap formation from the quantum mechanical point of view as well as the principles of n-type semiconductor materials that make them suitable photocatalysts. It then goes on to present in a concise manner the principles and drawbacks of TiO2 photoactivity and how these can be enhanced in order to allow higher efficiencies in the visible spectrum of light as well as reducing effects of electron-hole recombination. Within this frame metal and non-metal doping, use of organic dyes as well as semiconductor layering and noble metal deposition is considered. Finally this work emphasizes future directions in the enhancement of this promising material for applications in environmental engineering. Source


Ming R.,University of Illinois at Urbana - Champaign | Bendahmane A.,French National Institute for Agricultural Research | Bendahmane A.,King Saud University | Renner S.S.,Ludwig Maximilians University of Munich
Annual Review of Plant Biology | Year: 2011

Sex chromosomes in land plants can evolve as a consequence of close linkage between the two sex determination genes with complementary dominance required to establish stable dioecious populations, and they are found in at least 48 species across 20 families. The sex chromosomes in hepatics, mosses, and gymnosperms are morphologically heteromorphic. In angiosperms, heteromorphic sex chromosomes are found in at least 19 species from 4 families, while homomorphic sex chromosomes occur in 20 species from 13 families. The prevalence of the XY system found in 44 out of 48 species may reflect the predominance of the evolutionary pathway from gynodioecy towards dioecy. All dioecious species have the potential to evolve sex chromosomes, and reversions back from dioecy to various forms of monoecy, gynodioecy, or androdioecy have also occurred. Such reversals may occur especially during the early stages of sex chromosome evolution before the lethality of the YY (or WW) genotype is established. Copyright © 2011 by Annual Reviews. All rights reserved. Source


Al-Rejaie S.S.,King Saud University
Journal of Medical Sciences (Faisalabad) | Year: 2012

Numerous plant resin content essential oils with terpenes and sesquiterpenes have shown hepatoprotective activity. The aim of the present study was to investigate the hepatoprotective activity of Oleo-gum-resin (OGR) in rats. The hepatoprotective activity of OGR was evaluated in rats by assessing the ethanol-induced oxidative stress estimating alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphates (ALP), acid phosphatase (ACP), triglycerides (TG) and Total Cholesterol (TC) in plasma. In liver, glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), nucleic acids (DNA and RNA), total protein, TG and TC levels were estimated. Enzymatic activities were increased in plasma after ethanol administration and that was dose dependently decreased in OGR treated alcoholic animals. Similar effect was seen in lipid and MDA levels. Nucleic acids, GSH levels, SOD and CAT activities decreased by alcohol and protected with OGR treatments in dose dependent manner. The observed attenuation to ethanol's effect may be related to the biochemical changes induced, possibly, under the influence of different constituents (cinnamaldehyde, eugenol and terpenoids) of the OGR. However, OGR can contribute to alleviate the adverse effect of ethanol ingestion by enhancing the lipid metabolism and the hepatic antioxidant defense system. Source


Deraz N.M.,King Saud University
Journal of Analytical and Applied Pyrolysis | Year: 2012

Cerium based nickel catalysts synthesized by impregnation method have been characterized by XRD and TEM techniques. These catalysts can be described as a mixture of nickel oxide and ceria modified by the insertion of a part of nickel in the ceria lattice. The surface and catalytic properties of Ni/Ce mixed oxide solids were determined by nitrogen adsorption at 77 K and catalytic conversion of isopropanol at different temperatures. The results revealed that the heat treatment brought about different modifications in the structural, morphological, surface and catalytic properties of the as synthesized catalysts. From the characterization of the as prepared catalysts, it was concluded that the as prepared catalysts contain highly dispersed NiO, well crystalline NiO and CeO 2 and also Ni-Ce-O solid solution. This treatment led to a slightly increase in the crystallite size of ceria particles. On the other hand, the increase in the heat treatment resulted in an increase in the crystallite size, lattice constant and unit cell volume of nickel oxide. The formation of Ni-Ce-O solid solution with subsequent creation of oxygen vacancies increase as the heat treatment increases. However, the specific surface area, total pore volume and catalytic activity of the investigated system decrease as the preparation temperature increases from 500 to 700°C. The sintering activation energy of NiO and ceria were found to be 2.8 and 12.7 kJ/mol, respectively. © 2012 Elsevier B.V. All rights reserved. Source


Zain-Alabdeen E.H.,Dental Center Riyadh Medical Complex | Alsadhan R.I.,King Saud University
Dentomaxillofacial Radiology | Year: 2012

Objective: The aim of this study was to assess the accuracy and reliability of cone beam CT (CBCT) images compared with multidetector CT (MDCT) images for the detection of surface osseous changes in temporomandibular joints (TMJs). Methods: Naked-eye inspection of 110 sites in 10 TMJs from 5 dry human skulls provided the gold standard. Two radiologists interpreted the images. Sensitivity, specificity and kappa statistics were used for analysis. Results: The sensitivities of both modalities were low and comparable whereas the specificities were high and comparable. Intraobserver reliabilities for CBCT (p 5 0.0005) and for MDCT (p 5 0.0001) showed significant agreement. Interobserver reliability was higher for CBCT than for MDCT. Conclusion: CBCT and MDCT accuracy was comparable in detecting surface osseous changes with comparable intraobserver reliabilities. However, since CBCT requires less radiation exposure, it should be encouraged for imaging TMJ with suspected surface osseous changes. © 2012 The British Institute of Radiology. Source


Al-Numair K.S.,King Saud University
Journal of Food, Agriculture and Environment | Year: 2010

Diabetes mellitus is a major risk factor for the development of cardiovascular complications and cardiovascular disease. This study was undertaken to investigate the effect of camel milk on plasma glucose and plasma and tissue lipid profiles in streptozotocin-induced diabetic rats. Diabetes was induced in adult male albino rats of the Wistar strain, weighing 180-200 g, by administration of streptozotocin (40 mg/kg of body weight) intraperitoneally. Rats were randomly divided into five groups: Group I control animals (normal, nondiabetic animals), Group II camel milk control, Group III streptozotocin-diabetic, untreated animals, Group IV streptozotocin-diabetic animals given 250 mL/day camel milk, and Group V streptozotocin-diabetic animals given glibenclamide (600 μg/kg body weight). The levels of total cholesterol, triglycerides, free fatty acids and phospholipids, were assayed in the plasma besides lipoprotein-cholesterol (high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C) and very low density lipoprotein-cholesterol (VLDL-C)) and tissues (liver, kidney and heart). Total cholesterol, triglyceride, free fatty acid and phospholipid (LDL-C and VLDL-C in plasma only) levels increased in plasma and tissues significantly, while plasma HDL-cholesterol significantly decreased in diabetic rats. Treatment with camel milk prevented the above changes and improved towards normalcy. Thus administration of camel milk is able to reduce hyperglycemia and hyperlipidemia related to the risk of diabetes mellitus. Source


Al-Qattan M.M.,King Saud University
Journal of Hand Surgery: European Volume | Year: 2012

As a part of the pollicisation procedure, previous authors describe interosseous muscle and/or extensor tendon repositioning. The benefit of these tendon transfers has never been investigated despite the fact that other authors have used different techniques or do not perform some of these transfers routinely. In this paper, 16 children (17 hands) with isolated aplasia/hypoplasia of the thumb underwent the pollicisation procedure without any intrinsic tendon transfers. Surgery was performed at a mean age of 22 months and the mean follow-up time was 5 years. No early operative complications were seen. At final follow-up, the overall function and appearance of the hand was satisfactory in all patients. The results of our retrospective study warrant further investigation of these tendon transfers in a prospective comparative long-term study. © 2011 The British Society for Surgery of the Hand. Source


Khan A.S.,University of Maryland Baltimore County | Baig M.,King Saud University | Choi S.-H.,Sunchon National University | Yang H.-S.,Sunchon National University | Sun X.,Pacific Northwest National Laboratory
International Journal of Plasticity | Year: 2012

Measured responses of advanced high strength steels (AHSS) and their tailor welded blanks (TWBs), over a wide range of strain-rates (10 -4 to 10 3 s -1) are presented. The steels investigated include transformation induced plasticity (TRIP), dual phase (DP), and drawing quality (DQ) steels. The TWBs include DQ-DQ and DP-DP laser welds. A tensile split Hopkinson pressure bar (SHPB) was used for the dynamic experiments. AHSS and their TWB's were found to exhibit positive strain-rate sensitivity. The Khan-Huang-Liang (KHL) constitutive model is shown to correlate and predict the observed responses reasonably well. Micro-texture characterization of DQ steels, DQ-DQ and DP-DP laser welds were performed to investigate the effect of strain-rate on texture evolution of these materials. Electron backscatter diffraction (EBSD) technique was used to analyze the micro-texture evolution and kernel average misorientation (KAM) map. Measurement of micro-hardness profile across the cross section of tensile samples was conducted to understand the effect of initial microstructure on ductility of laser weld samples. © 2011 Elsevier Ltd. All rights reserved. Source


Analytical solutions of the Schrödinger equation for the one-dimensional quantum well with all possible permutations of the Dirichlet and Neumann boundary conditions (BCs) in perpendicular to the interfaces uniform electric field E are used for the comparative investigation of their interaction and its influence on the properties of the system. Limiting cases of the weak and strong voltages allow an easy mathematical treatment and its clear physical explanation; in particular, for the small E, the perturbation theory derives for all geometries a linear dependence of the polarization on the field with the BC-dependent proportionality coefficient being positive (negative) for the ground (excited) states. Simple two-level approximation elementary explains the negative polarizations as a result of the field-induced destructive interference of the unperturbed modes and shows that in this case the admixture of only the neighboring states plays a dominant role. Different magnitudes of the polarization for different BCs in this regime are explained physically and confirmed numerically. Hellmann-Feynman theorem reveals a fundamental relation between the polarization and the speed of the energy change with the field. It is proved that zero-voltage position entropies Sx are BC independent and for all states but the ground Neumann level (which has Sx=0) are equal to ln2-1 while the momentum entropies Sk depend on the edge requirements and the level. Varying electric field changes position and momentum entropies in the opposite directions such that the entropic uncertainty relation is satisfied. Other physical quantities such as the BC-dependent zero-energy and zero-polarization fields are also studied both numerically and analytically. Applications to different branches of physics, such as ocean fluid dynamics and atmospheric and metallic waveguide electrodynamics, are discussed. © 2015 The Authors. Annalen der Physik published by Wiley-VCH Verlag GmbH & Co. KGaA Weinheim. Source


Ali Q.,University of Agriculture at Faisalabad | Ashraf M.,University of Agriculture at Faisalabad | Ashraf M.,King Saud University
Journal of Agronomy and Crop Science | Year: 2011

The present investigation was conducted to assess the ameliorative effects of foliar-applied trehalose on growth, photosynthetic attributes, water relation parameters and oxidative defence mechanism in two maize cultivars under field water deficit conditions. Various components of the experiment comprised two maize cultivars (EV-1098 and Agaiti-2002), two water-stress levels (irrigation after 2weeks and irrigation after 3weeks during the entire period of growth), and two levels of trehalose (0 and 30mm) and four replicates of each treatment. Water stress significantly reduced the plant biomass production, photosynthetic attributes and water relation parameters in both maize cultivars. In contrast, water stress considerably increased the leaf malondialdehyde (MDA) contents, the activities of antioxidant enzymes such as peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), and the levels of non-enzymatic compounds such as ascorbic acid and tocopherols. In contrast, water stress caused a marked reduction in leaf phenolic contents. Foliar-applied trehalose significantly increased plant biomass production, and improved some key photosynthetic attributes and plant-water relation parameters. The ameliorative effect of exogenously applied trehalose was also observed on the activities of some key antioxidant enzymes (POD and CAT) and non-enzymatic compounds (tocopherols and phenolics). Overall, exogenously applied trehalose considerably improved drought tolerance of maize plants by up-regulating photosynthetic and water relation attributes as well as antioxidant defence mechanism. © 2011 Blackwell Verlag GmbH. Source


Atangana A.,University of the Free State | Alkahtani B.S.T.,King Saud University
Entropy | Year: 2015

Using some investigations based on information theory, the model proposed by Keller and Segel was extended to the concept of fractional derivative using the derivative with fractional order without singular kernel recently proposed by Caputo and Fabrizio. We present in detail the existence of the coupled-solutions using the fixed-point theorem. A detailed analysis of the uniqueness of the coupled-solutions is also presented. Using an iterative approach, we derive special coupled-solutions of the modified system and we present some numerical simulations to see the effect of the fractional order. © 2015 by the authors. Source


Kassem H.A.,King Saud University
Journal of Soil Science and Plant Nutrition | Year: 2012

An experiment was conducted during two successive seasons, 2008/2009 and 2009/2010, on the Zaghloul date palm cultivar grown in calcareous loamy sand and irrigated with drainage water. The purpose of the experiment was to investigate the effects of 1,000 g total N per palm applied as either ammonium sulphate, ammonium nitrate or urea and two levels of potassium (K2O) and elemental sulphur (S) on the nutritional status, productivity and fruit quality of the cultivar. The results of the study showed that the ammonium sulphate form (N1) increased the fruit yield, weight, length and colour compared to the ammonium nitrate (N2) or the urea form (N3). Fruit TSS, sugars, anthocyanin and dry matter content increased, whereas fruit acidity and tannins decreased under N1 fertilisation. Furthermore, the potassium and sulphur fertilisation enhanced the physico-chemical characteristics of the fruit. The N1 application increased the leaf N, K, Ca, Fe and Zn contents, as did the potassium and sulphur application. The N1 application increased the fruit N, P, K, Fe and Zn contents, whereas the fruit Cd, Pb and NO3 were highest with N2. The potassium and sulphur applications increased the fruit N, Fe, Mn, Cd, Pb and NO3 contents. Source


Abudabos A.M.,King Saud University
Italian Journal of Animal Science | Year: 2012

The first aim of this study was to examine the effects of strain and age on phytate phosphorus (PP) utilization and intestinal phytase activity (IPA) in two strains of laying hens, Hy-line Brown (HB) and Hy-line White W-36 (HW) at 32, 52 and 72 weeks of age. A digestion trial was conducted using the indicator method and birds were sampled to measure IPA. The second aim was to examine the effect of feed grade exogenous phytase enzyme on total (TP), water soluble (WSP) and phytate phosphorus (PP) excretion in the HW strain fed varying levels of phosphorus. Hens were fed three concentrations of available P (AP): 0.2, 0.3 and 0.4%. Each level of P was supplemented with three levels of commercial feed grade exogenous phytase enzyme (0, 300, and 600 FTU/kg) and the amount of TP, WSP and PP in excreta per 100 g of feed consumed was calculated. The HB retained more PP as compared to HW. Intestinal phytase activity showed a significant (P<0.01) age effect with the highest activity occurring at 32 weeks. There were significant differences in the amount of TP and SP excreted between birds receiving the 3 levels of phosphorus with 300 units phytase (P<0.01). The results of this study showed that layers are capable of utilizing P P, and that utilization is regulated by IPA and varies with age. Exogenous phytase improved PP utilization but it increased the amount of TP and WSP in excreta. © A.M. Abudabos, 2012. Source


Finite-strain was studied in the mylonitic granitic and metasedimentary rocks in the northern thrust in Wadi Mubarak belt to show a relationship to nappe contacts between the old granitic and metavolcano-sedimentary rocks and to shed light on the heterogeneous deformation for the northern thrust in Wadi Mubarak belt. We used the Rf/Φ and Fry methods on feldspar porphyroclasts, quartz and mafic grains from 7 old granitic and 7 metasedimentary samples in the northern thrust in Wadi Mubarak belt. The finite-strain data shows that old granitic rocks were moderate to highly deformed and axial ratios in the XZ section range from 3.05 to 7.10 for granitic and metasedimentary rocks. The long axes (X) of the finite-strain ellipsoids trend W/WNW and E/ENE in the northern thrust in Wadi Mubarak belt. Furthermore, the short axes (Z) are subvertical associated with a subhorizontal foliation. The value of strain magnitudes mainly constants towards the tectonic contacts between the mylonitic granite and metavolcano-sedimentary rocks. The data indicate oblate strain symmetry (flattening strain) in the mylonitic granite rocks. It is suggested that the accumulation of finite strain was formed before or/and during nappe contacts. The penetrative subhorizontal foliation is subparallel to the tectonic contacts with the overlying nappes and foliation was formed during nappe thrusting. © 2011 Pleiades Publishing, Ltd. Source


Frontera A.,University of the Balearic Islands | Gamez P.,University of Barcelona | Mascal M.,University of California at Davis | Mooibroek T.J.,Leiden University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

Supramolecular chemistry is a field of scientific exploration that probes the relationship between molecular structure and function. It is the chemistry of the noncovalent bond, which forms the basis of highly specific recognition, transport, and regulation events that actuate biological processes. The classic design principles of supramolecular chemistry include strong, directional interactions like hydrogen bonding, halogen bonding, and cation-π complexation, as well as less directional forces like ion pairing, π-π, solvophobic, and van der Waals potentials. In recent years, the anion-π interaction (an attractive force between an electron-deficient aromatic π system and an anion) has been recognized as a hitherto unexplored noncovalent bond, the nature of which has been interpreted through both experimental and theoretical investigations. The design of selective anion receptors and channels based on this interaction represent important advances in the field of supramolecular chemistry. The objectives of this Review are 1) to discuss current thinking on the nature of this interaction, 2) to survey key experimental work in which anion-π bonding is demonstrated, and 3) to provide insights into the directional nature of anion-π contact in X-ray crystal structures. As easy as π systems found it to bond with cations, they concealed their attraction to anions until they were spotted together in too many crystal structures for it to be mere coincidence. Today, the anion-π relationship has an established place in the repertory of noncovalent interactions. Extensive theoretical and experimental studies illuminate the physical nature of the interaction and its utility in the design of hosts, and the engineering of solid-state structures. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Zaidi F.K.,King Saud University
Journal of the Geological Society of India | Year: 2011

Drainage basin morphometry is a quantitative way of describing the characteristics of the surface form of a drainage basin and provides important information about the region's topography and underlying geological structures. It plays an important role in hydrogeological investigations for delineating zones of adequate groundwater potential and selecting sites for construction of artificial recharge structures. In the present study an attempt was made to discover the stream properties in the Gagas River Basin of Almora district in the state of Uttarakhand using the various stream attributes. Based on the study the potential zones for the construction of artificial recharge structures in the basin were identified. © 2011 Geological Society of India. Source


Deraz N.M.,King Saud University
Journal of Analytical and Applied Pyrolysis | Year: 2011

Zinc ferrite nano-powders with a nominal composition of ZnFe 2O 4 were prepared by combustion synthesis using mixture of urea and ammonium nitrate as fuel. The influence of alumina-doping on the structural, morphological and magnetic properties of ZnFe 2O 4 nano-particles was investigated by means of X-ray powder diffraction (XRD), infrared (IR) spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and vibrating sample magnetometer (VSM). XRD and IR analyses confirm the cubic spinel phase of ZnFe 2O 4 nano-particles. The Zn ferrite presented a uniform microstructure with grain size in nano-scale. Alumina-doping brought about a change in the morphology of the as prepared ferrite from sphere-like to regular hexagon. Al 2O 3-treatment led to a decrease in the coercivity (H c), magnetization (M s) and magnetic moment (n B) of the investigated system. The maximum decrease in the values of H c, M s and n B due to the treatment with 1.5 wt% Al 2O 3 attained 13.5, 17.4 and 13.5%, respectively. The observed results can be explained on the basis of particle size and the Fe 3+ concentration in the octahedral and tetrahedral sites involved in the cubic spinel structure. © 2011 Elsevier B.V. All rights reserved. Source


Wahabi H.A.,King Saud University
Cochrane database of systematic reviews (Online) | Year: 2011

Miscarriage is a common complication encountered during pregnancy. The role of progesterone in preparing the uterus for the implantation of the embryo and its role in maintaining the pregnancy have been known for a long time. Inadequate secretion of progesterone in early pregnancy has been linked to the aetiology of miscarriage and progesterone supplementation has been used as a treatment for threatened miscarriage to prevent spontaneous pregnancy loss. To determine the efficacy and the safety of progestogens in the treatment of threatened miscarriage. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (December 2009) and bibliographies of all located articles for any unidentified articles. Randomized or quasi-randomized controlled trials that compare progestogen with placebo, no treatment or any other treatment given in an effort to treat threatened miscarriage. At least two authors assessed the trials for inclusion in the review and extracted the data. Two studies (84 participants) were included in the meta-analysis. In one study, all the participants met the inclusion criteria and in the other study, only the subgroup of participants who met the inclusion criteria was included in the meta-analysis. There was no evidence of effectiveness with the use vaginal progesterone compared to placebo in reducing the risk of miscarriage (risk ratio 0.47; 95% confidence interval 0.17 to 1.30). Based on scarce data from two methodologically poor trials, there is no evidence to support the routine use of progestogens for the treatment of threatened miscarriage. Information about potential harms to the mother or child, or both, with the use of progestogens is lacking. Further, larger, randomized controlled trials on the effect of progestogens on the treatment of threatened miscarriage, which investigate potential harms as well as benefits, are needed. Source


Closed type III phalangeal neck fractures with 180-degree rotation is a rare iatrogenic injury that occurs following failed attempts at closed reduction. Prior to closed reduction, the phalangeal head is in 90-degree rotation. Longitudinal traction during closed reduction then converts the deformity into 180-degree rotation. We present the first documented noniatrogenic case of phalangeal neck fracture with 180-degree rotation that was also associated with a displaced Salter-Harris II fracture at the same joint. The blood supply of the phalangeal head in that scenario is discussed along with precautions that should be taken during open reduction and internal fixation to avoid avascular necrosis of the phalangeal head. Copyright © 2012 by Lippincott Williams & Wilkins. Source


Ramadan M.Z.,King Saud University
Work | Year: 2011

Objective: The goal of this research was to study the effect of adjustable imported desk and chair combinations available in the market on student performance. Methods: Six sets of chairs and tables within three different activities (reading, writing, and looking to the blackboard) were the independent variables. Evaluation of back force at 5th lumbar vertebrae and the 1st sacrum (L5/S1), subjective measures of discomfort, and the mismatch between student body dimension and classroom furniture analysis were measured. Participants: A total of 124 young male students (first through sixth-grade) participated in this experiment. Results: The results revealed too low or too high chair and table heights relative to the students' body dimensions increased the stresses acting at L5/S1 as well as discomfort ratings. Conclusions: This study indicated there was a high level of body mismatch in desk-chair combinations even with the adjustable imported furniture available in the local market. Anthropometric data of Saudi students should be collected from different regions in the Kingdom and then design and development of desk-chair combinations could follow the development of a standard procedure to adapt to the needs of Saudi school children. © 2011 - IOS Press and the authors. All rights reserved. Source


Al-Kahtani S.H.,King Saud University
Journal of Animal and Plant Sciences | Year: 2012

This study aimed to analyze the most important factors in rationalizing the consumption of domestic water, and then identify the most appropriate water policies to be applied to maintain supply and consumption of domestic water. The study was mainly relying on primary data in the form of a questionnaire designed to achieve the objectives of the study. Descriptive statistical measures have been applied to assess the impact of some factors on the rationalization of water consumption, as well as the use the multinomial logit model to estimate the proportion of households water consumption, which is located in the various segments of the block price, and finally multi-regression model has been applied to estimate the average household consumption in different segments. The results revealed that 11% of the water consumers are affected by water conservation campaigns organized by the Ministry of water and electricity, while 58% (a high percentage) are not affected by the rationalization campaigns, which indicates that the voluntary policy is not feasible in the short term and that the ministry should search for complementary policy of water demand management to be more influential on the rationalization of water consumption. Source


Javed F.,King Saud University | Romanos G.E.,State University of New York at Stony Brook
Photomedicine and Laser Surgery | Year: 2013

Objective: The aim of this study was to assess whether or not photodynamic therapy enhanced standard antibacterial therapy in dentistry. Background data: Photodynamic therapy when used as an adjunct to conventional periodontal therapy kills more bacteria than when conventional periodontal therapy is used alone. Materials and methods: To address the focused question, "Does photodynamic therapy enhance killing of oral bacteria?" PubMed/MEDLINE® and Google Scholar databases were explored. Original human and experimental studies and studies using photodynamic therapy for killing oral bacteria were included. Letters to the Editor, historic reviews, and unpublished data were excluded. Results: Photodynamic therapy significantly reduces periodontopathogenic bacteria including Aggregatibacter actinomycetemcomitans, Prevotella intermedia, and Porphyromonas gingivalis. Photodynamic therapy kills cariogenic bacteria (such as Streptococcus mutans and Streptococcus sanguis), bacteria associated with infected root canals, and those associated with periimplantitis. Conclusions: Photodynamic therapy, when used as an adjunct to conventional oral disinfection protocols, enhances standard antibacterial therapy in dentistry. © Mary Ann Liebert, Inc. Source


Nafady A.,Monash University | Nafady A.,King Saud University | O'Mullane A.P.,RMIT University | Bond A.M.,Monash University
Coordination Chemistry Reviews | Year: 2014

TCNQ- radical anions (TCNQ=7,7,8,8,-tetracyanoquinodimethane) form a wide range of semiconducting coordination polymers when coordinated to transition metals. Some materials such as CuTCNQ and AgTCNQ exhibit molecular switching and memory storage properties; others have intriguing magnetic properties and for example may behave as molecular magnets at low temperature. In this review, the electro- and photo-chemical synthesis and characterization of this important class of material is reviewed. In particular, the electrochemistry and the redox properties of TCNQ derivatives of coordination polymers based on Cu, Ag, Mn, Fe, Co, Ni, Zn and Cd transition metals are surveyed, with an emphasis on the mechanistic aspects of their electrochemical formation via nucleation-growth processes. Given that TCNQ is an extremely good electron acceptor, readily forming TCNQ- and TCNQ2-, electrochemical reduction of TCNQ in the presence of a transition metal ion provides an ideal method for synthesis of metal-TCNQ materials by electrocrystallization from organic solvents and ionic liquids or solid-solid transformation using TCNQ modified electrodes from aqueous media containing transition metal electrolytes. The significance of the reversible formal potential (E0f) in these studies is discussed. The coupling of electrocrystallization on electrode surfaces and microscopic characterization of the electrodeposited materials reveals a wide range of morphologies and phases which strongly influence their properties and applications. Since TCNQ can also be photo-reduced in the presence of suitable electron donors, analogous photochemical approaches to the synthesis of TCNQ-transition metal derivatives are available. The advantages of electrochemical and photochemical methods of synthesis relative to chemical synthesis are outlined. © 2014 Elsevier B.V. Source


Egypt is characterized as a "water scarce" country, with limited fresh water supplies, and is expected to be under water stress by the year 2030. Therefore, it is important to develop any available means to supply water to maintain human life, such as runoff harvesting approach. The curve number (CN) is a hydrologic parameter used to describe the stormwater runoff potential for drainage areas, and it is a function of land use, soil type, and soil moisture. This study was conducted to estimate the potential runoff coefficient (PRC) using geographic information system (GIS) based on the area's hydrologic soil group (HSG), land use, slope and determine the runoff volume. The soil map of Egypt was extracted from the soil map of the world and then was used in building a soil hydrological group map. Landsat image 5/7 TM/ETM was incorporated with land cover data to generate land use and land cover (LULC) map. Slope map for Egypt was generated from a 30m DEM. The GIS technique was used to generate PRC map. Annual runoff depth is derived based on the annual rainfall surplus and runoff coefficient per pixel using raster calculator tool in ArcGIS. A variation from as low as 0 to a maximum of 180mm was observed due to divergence in topography and climate in Egypt where the largest rainfall was observed in the northern part of the country. Generally, the result of this study indicates that in the absence of reliable ground measurements of rainfall, the product can satisfactorily be applied to estimate the spatial rainfall distribution based on values of R and R2 (0.94) obtained. © 2014 Elsevier B.V. Source


Al-Gaadi K.A.,King Saud University
American Journal of Agricultural and Biological Science | Year: 2012

An experiment on a sandy soil field was conducted to investigate the potential of determining soil compaction from apparent soil Electrical Conductivity (ECa) measured by Electromagnetic Induction (EMI) technique. A soil conductivity meter (EM38) was used to measure ECa under four soil Moisture Contents (MC) (4.965.336.94 and 8.0%) and a range of Soil Compaction (SC) levels (on the average, from 220 to 2070 kPa). At each MC and SC level, EM38 measurements were recorded at three EM38 heights above the ground (0, 20 and 40 cm) and at vertical and horizontal device orientation. Except at the MC of 8.0%, results revealed that the measured ECa was proportional to SC at all considered soil conditions and modes of measurement (EM38 orientation and height). For all soil conditions and modes of measurement, an overall mean of the coefficient of correlation (R2) of 0.66 was observed between SC and ECa at soil MC of up to 6.94%. Thus, ECa measurement can be an indicator of soil compaction, given that the MC is below 7% in sandy soil. For both EM38 orientations, higher correlations between SC and soil ECa (average R2 of 0.90) were observed with the EM38 placed on the ground (0 cm height) compared to those achieved at 20 cm and 40 cm height, where the average R2 values were 0.62 and 0.47, respectively. At 0 cm height and MC of up to 6.94%, higher correlations between SC and ECa were obtained at vertical EM38 orientation (average R2 of 0.98) compared to those at horizontal orientation (average R2 of 0.81). © 2012 Science Publication. Source


Asif M.,King Saud University
Chemical Engineering and Technology | Year: 2010

The layer-inversion behavior of down-flow binary solid-liquid fluidized beds is predicted using the property-averaging approach. The binary pair in this case consists of a larger solid species which is also heavier than its smaller counterpart, while both are lighter than the fluidizing medium. The model is based on using the generalized Richardson-Zaki correlation for evaluation of the bed void fraction wherein mean values of particle properties are used. However, unlike the maximum bulk density condition for the conventional up-flow binary solid fluidized bed, the model is based on a minimum bulk density condition for occurrence of layer inversion. This is due to the fact that the volume contraction phenomenon associated with the mixing of unequal solid species leads to a decrease in bulk density of the bed. Model predictions are also compared using the limited data available in the literature. Predictions are consistent with the observed mixing behavior. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


The performance of the upflow anaerobic sludge blanket reactor that used red mud-iron (RM-Fe) for methane production for the treatment of palm oil mill effluent (POME) at various hydraulic retention time (HRT) was determined. POME was used as the substrate carbon source. The biogas production rate was 1.7 l biogas/h with a methane yield of 0.78 l CH4/g CODremoved and chemical oxygen demand (COD) removal was 85% at POME concentration of 30 g COD/l at HRT 16 h. The reactor R2 showed average methane content of biogas and COD reduction of 78% and 85% at 400 mg/l RM-Fe. Significant increase in the granule diameter (up to 2900 m) in R2 was compared to control R1 (up to 86 m) at end of the experiment. © 2014 Taylor & Francis. Source


Khan A.S.,University of Maryland Baltimore County | Baig M.,King Saud University
International Journal of Plasticity | Year: 2011

Finite deformation anisotropic responses of AA5182-O, over a wide range of strain-rates (10-4 to 100 s-1) and temperatures (293-473 K) are presented. The plastic anisotropy parameters were experimentally determined from tensile experiments using specimens from sheet material. Using the experimental results under plane stress conditions, the anisotropy coefficients for Barlat's yield function (YLD96) were calculated at different strain-rates and temperatures. The correlations obtained from YLD96 are in good agreement with the observed experimental results. The strain-rate sensitivity of AA5182-O alloy changed from negative at 293 K to positive at 473 K. Khan-Huang-Liang (KHL) constitutive model is shown to correlate the observed strain-rate and temperature dependent responses reasonably well. The material parameters were obtained from the experimental responses along the rolling direction (RD) of the sheet. Marciniak and Kuckzinsky (M-K) theory was used to obtain the theoretical strain and stress-based forming limit curves (FLCs) at different strain-rates and temperatures. The experimental result from the published literature is compared with the FLCs from the current study. © 2010 Elsevier Ltd. All rights reserved. Source


Al-Othman Z.A.,King Saud University | Ali I.,Jamia Millia Islamia University
Biomedical Chromatography | Year: 2012

A fast, economic, reproducible, accurate, effective, rugged and selective chiral-HPLC method was developed and validated for the enantiomeric resolution of nebivolol enantiomers [(+)-RRRS and (-)-SSSR)] in dosage formulation. The method was rapid as chiral separation occurred within only 12min. The mobile phase used was n-heptane-ethanol-DEA (85:15:0.1, v/v) at 3.0mL/min flow-rate with 225nm detection. The column used was an amylase-based 3-AmyCoat (150×46mm) [tris-(3,5-dimethylphenyl carbamate)]. The capacity factors of (+)-RRRS and (-)-SSSR enantiomers were 7.85 and 10.90 while the separation and resolution factors were 1.39 and 1.83, respectively. The limits of detection and quantitation for (+)-RRRS enantiomer were 4.5 and 10.00μg/mL, while these values for (-)-SSSR enantiomer were 4.1 and 8.2μg/mL, respectively. The linearity was observed in the concentrations range of 0.10-1.0mg/mL for both enantiomers. The π-π interactions, hydrogen bonds, dipole-dipole interactions and steric effects control the chiral resolution of nebivolol enantiomers on the reported chiral column. The reported method can be used for the quality control of nebivolol in pharmaceutical preparations with good economy. In addition, this method can also be used for the analysis of (+)-RRRS and (-)-SSSR) enantiomers in biological and environmental samples. © 2011 John Wiley & Sons, Ltd. Source


Alhogail A.,King Saud University
Computers in Human Behavior | Year: 2015

Establishing information security culture in organizations impacts employees' perceptions and security behavior in a way that can guard against many information security threats posed by insiders. This paper is concerned with the development of a comprehensive information security culture framework for organizations. The structured STOPE (Strategy; Technology; Organization; People; and Environment) scope has been used as a base for the framework so that the various issues of information security can be integrated. The resulted framework incorporates the four main domains of the human factor diamond: preparedness, responsibility, management, and society and regulations. The framework also incorporates change management principles that guide the cultivation of the information security culture. The framework is validated by surveying experts to provide their views and feedback on the correctness and comprehensiveness of the framework structure and its associated tasks. The framework can assist organizations to develop an effective information security culture that protects their information assets. © 2015 Elsevier Ltd. Source


Al-Qattan M.M.,King Saud University
Annals of Plastic Surgery | Year: 2013

Protein regulation is the function of several pathways and enzyme systems in the human body. One of these pathways is the ubiquitin/SUMO pathway. The author has noted that almost all known syndromes of radial ray deficiency are related to this pathway. In this article, these syndromes are reviewed with special attention to their relationship with the ubiquitin/SUMO pathway. This opens a new insight into the pathogenesis of radial ray deficiency syndromes. Copyright © 2013 by Lippincott Williams & Wilkins. Source


The optimum design of the proportional-integral-derivative (PID) controller plays an important role in achieving a satisfactory response in the automatic voltage regulator (AVR) system. This paper presents a novel optimal design of the PID controller in the AVR system by using the Taguchi combined genetic algorithm (TCGA) method. A multiobjective design optimization is introduced to minimize the maximum percentage overshoot, the rise time, the settling time, and the steady-state error of the terminal voltage of the synchronous generator. The proportional gain, the integral gain, the derivative gain, and the saturation limit define the search space for the optimization problem. The approximate optimum values of the design variables are determined by the Taguchi method using analysis of means. Analysis of variance is used to select the two most influential design variables. A multiobjective GA is used to obtain the accurate optimum values of these two variables. MATLAB toolboxes are used for this paper. The effectiveness of the proposed method is then compared with that of the earlier GA method and the particle swarm optimization method. With this proposed TCGA method, the step response of the AVR system can be improved. © 2007-2012 IEEE. Source


Al-Dhabi N.A.,King Saud University
Saudi Journal of Biological Sciences | Year: 2013

For consumption of health foods of Spirulina, by the general public, health food stores are increasingly offering more exotic products. Though Spirulina consumption is growing worldwide, relatively few studies have reported on the quantities of heavy metals/minerals they contain and/or their potential effects on the population's health. This study reveals the concentrations of six typical heavy metals/minerals (Ni, Zn, Hg, Pt, Mg, and Mn) in 25 Spirulina products commercialized worldwide for direct human consumption. Samples were ground, digested and quantified by Coupled Plasma Mass Spectroscopy (ICP-MS). The concentrations (mg/kg d.w.) were range from 0.001 to 0.012 (Pt) followed by 0.002-0.028 (Hg), 0.002-0.042 (Mg), 0.005-2.248 (Mn), 0.211-4.672 (Ni) and 0.533-6.225 (Zn). The inorganic elements of the present study were significantly lower than the recommended daily intake (RDI) level of heavy metal elements (mg/daily) Ni (0.4), Zn (13), Hg (0.01), Pt (0.002), Mg (400) and Mn (4). Based on this study the concentration of inorganic elements was not found to exceed the present regulation levels, and they can be considered as safe food. © 2013 . Source


Hepbasli A.,Ege University | Hepbasli A.,King Saud University
Energy Conversion and Management | Year: 2010

Geothermal is a reliable and promising renewable energy. In 1892 the first geothermal district heating system (GDHS) began operations in Boise, Idaho, USA. Since then, a number of GDHSs installations have been made worldwide. Various investigations on the efficient utilization of geothermal energy resources have also been conducted to attain sustainable development. There is a link between exergy and sustainable development. In recent years, exergy analysis has been widely used in the design, simulation and performance assessment of thermal systems. Exergoeconomic analysis, which is a combination of exergy and economics, is nowadays considered a powerful tool to study and optimize various types of energy-related systems. The present study comprehensively reviews GDHSs in terms of three aspects, namely energetic, exergetic and exergoeconomic analyses and assessments, for the first time to the best of the author's knowledge. A brief historical development of the studies on GDHSs was given on the base of these three aspects first. Next, GDHSs analyzed were schematically presented and shortly described. The previously conducted studies on GDHSs were then reviewed and classified. Finally, the conclusions were presented. It is expected that this comprehensive study will be very beneficial to everyone involved or interested in the energetic, exergetic and exergoeconomic design, analysis and performance evaluation of GDHSs. © 2010 Elsevier Ltd. All rights reserved. Source


Al-Hoqail I.A.,King Saud University
Current Vascular Pharmacology | Year: 2010

Personalized medicine is a new treatment modality where patients are the center of interest. Thus, 1 drug does not fit all; rather we look for a drug which fits the individual patients' disease. Treatment is moving towards molecular medicine driven by the growing knowledge and understanding of pharmacogenetics. Psoriasis is a common dermatological disease characterized by genetic polymorphism. The association of biomarkers and psoriasis is helpful to evaluate susceptibility to the disease, its severity and its progression. Additionally, the response to treatment will be anticipated. The growing expenses of health care systems worldwide are primarily due to increasing costs of chronic disease management. Hence, activation of preventive medicine will minimize treatment costs. A revolution in treatment modalities is expected to start at the level of pharmaceutical companies, as personalization of medicine will decrease the cost of clinical trials by minimizing the number of subjects required. In turn, this will decrease the cost of developing new medications. My vision for the future is that personalized medicine will mandate special physicians capable of understanding molecular medicine and using genetics and biomarkers for diagnosis, evaluation of the effect of drugs and overall prognosis. This new therapeutic modality will need special training. © 2010 Bentham Science Publishers Ltd. Source


Four important commercial aluminum alloys, namely 1050, 5083, 6082 and 7010AA are processed through a single pass via two equal channel angular pressing (ECAP) dies with different geometries (die angles of 90° and 120°). Electron back scattered diffraction (EBSD) is applied on the flow plane of the processed samples. Large scans with a step size of 7 μm for grain size distribution and texture measurements, as well as small scans with a step size of 0.1 μm for determination of cell size distribution, were performed. Hardness and simple compression are employed to evaluate the mechanical properties of the ECAP processed samples. Shear bands in the ECAP processed 7010AA was a major feature that led to failure in all samples subjected to further simple compression. The hardness as well as the stress-strain behavior was similar in the ECAP processed 6082 and 5083AA. The die geometry and the strain involved in the single pass influenced the overall texture intensity developed in the wrought alloys (1050 and 5083AA) and had minimal influence on the texture intensity of the heat treatable alloys (6082 and 7010AA). Low angle grain boundaries dominated the microstructure of all alloys for all testing conditions. © 2011 Elsevier Ltd. Source


Al-Saud M.S.,King Saud University
IET Generation, Transmission and Distribution | Year: 2011

This paper builds on a previously published development work involving a novel thermal field sensitivity model for underground cable systems, based on finite elements, which has been verified by experimental laboratory measurements. The paper reports on a new approach to underground cable thermal field optimisation using a proposed concept of perturbed finite-element analysis. This concept is not restricted to the conventional thermal field evaluation; rather it involves two main achievements. First, it derives sensitivity coefficients associated with various cable parameters of interest, and provides a quick sensitivity methodology based on the finite element model, to assess the cable thermal performance subjected to variations in the cable thermal circuit parameters, without repeating the finite element analysis for each possible parameter change. Second, it introduces an optimisation model for the underground power cable thermal circuit, based on generated gradients. The derived sensitivity coefficients are utilised for another important advantage in calculating the gradient of the desired objective function. This general framework of power cable performance optimisation uses the perturbed finite element method, which enables calculation of the objective function value and its gradient, without sacrificing the model accuracy. The developed algorithm was applied to various benchmark cable systems of 69 and 380 kV for different practical cable performance optimisation objectives. © The Institution of Engineering and Technology 2011. Source


Hepbasli A.,King Saud University
Applied Energy | Year: 2011

This study deals with modeling and analyzing the performance of greenhouses from the power plant through the heating system to the greenhouse envelope using exergy analysis method, the so-called low exergy or LowEx approach, which has been and still being successfully used in sustainable buildings design, for the first time to the best of the author's knowledge. For the heating applications, three options are studied with (i) a solar assisted vertical ground-source heat pump greenhouse heating system, (ii) a wood biomass boiler, and (iii) a natural gas boiler, which are driven by renewable and non-renewable energy sources. In this regard, two various greenhouses, the so-called small greenhouse and large greenhouse, considered have heat load rates of 4.15kW and 7.5MW with net floor areas of 11.5m2 and 7.5ha, respectively. The overall exergy efficiency values for Cases 1-3 (solar assisted vertical ground-source heat pump, natural gas boiler and wood biomass boiler) of the small greenhouse system decrease from 3.33% to 0.83%, 11.5% to 2.90% and 3.15% to 0.79% at varying reference state temperatures of 0 to 15°C while those for Cases 1 and 2 (wood biomass and natural gas boilers) of the large greenhouse system decrease from 2.74% to 0.11% and 4.75% to 0.18% at varying reference state temperatures of -10% to 15°C. The energetic renewability ratio values for Cases 1 and 3 of the small greenhouse as well as Case 1 of the large greenhouse are obtained to be 0.28, 0.69 and 0.39, while the corresponding exergetic renewability ratio values are found to be 0.02, 0.64 and 0.29, respectively. © 2011 Elsevier Ltd. Source


Alharbi K.K.,King Saud University
DNA and cell biology | Year: 2014

Type 2 diabetes mellitus (T2DM) is a common chronic metabolic disorder characterized by persistent hyperglycemia. It is considered to be a major risk factor for obesity and cardiovascular diseases. The cause of T2DM is likely due to a complex interaction between genetic and environmental factors. Apolipoprotein E (ApoE) gene plays a key role in lipid metabolism. The aim of this contemporary study was to investigate the ApoE polymorphism in a Saudi population with T2DM subjects. Two common single-nucleotide polymorphisms, that is, rs429358 and rs7412, in the ApoE gene were genotyped by TaqMan assay in T2DM patients (n=438) and controls (n=460). The results of the present study indicate that ApoE polymorphism was significantly associated with T2DM in a Saudi population with the e2 and e4 alleles (p=0.0001). We found statistically significant difference in the genotype distribution between T2DM patients and controls [for E4/E4: OR, 4.39 (95% CI: 2.16-8.92); p=0.0001]. A significant difference was observed in the lipid profile parameters, like triglycerides, low-density lipoprotein, and ApoE alleles (p=0.0001). Further studies are carried out in a Saudi population with different diseases to confirm the risk allele. In conclusion, our study results suggest that ApoE variants constitute risk markers of T2DM in a Saudi population. Source


Choleoeimeria mitranusensis n. sp. is described from the gall bladder of the lizard Scincus mitranus in Saudi Arabia. The prevalence of the infection was 20% (6/30). Oocysts were ellipsoidal and measured 29 m × 20 m. Sporocysts were dizoic and elliptical in shape. The endogenous development was confined to the gall bladder epithelium. Meronts, gamonts, and young oocysts were detected. © 2011 American Society of Parasitologists. Source


Al-Ghobari H.M.,King Saud University
Journal of Agricultural Science and Technology | Year: 2014

System evaluations were performed on 48 center pivots in different parts of Saudi Arabia. These systems, located on different farms in four different regions of the country, namely: Riyadh, Jouf, Qassim and Eastern regions, were evaluated to study the effect of lateral configuration on water application uniformity as regards the original vs. modified laterals. Lateral configuration modifications have been made by the local farmers through a chang of the position of the lateral and spray nozzles from the original design. Depths of water distribution along the lateral, Coefficient of uniformity (Cu) and Distribution uniformity of the low quarter (Du) were determined and compared for the original and modified laterals under field conditions. The average values of Cu for original systems ranged between 71.81 and 89.46% with an overall average of 82.69%, whereas the average values of Cu for modified systems ranging between 61.35 and 84.33% with an overall average of 78.05%. Also, the values of Du ranged between 54.14 and 81.81% with an overall average of 73.24% for the original systems, while these values for the modified systems ranging between 31.45 and 77.07% with an overall average of 66.87%. The results finally indicated that the values of uniformity for original vs. modified laterals were significantly different indicating that there existed a noticble adverse effect of center pivot lateral configuration on the uniformity of water application. Source


Zhani K.,University of Sfax | Ben Bacha H.,King Saud University
Renewable Energy | Year: 2010

This paper tackles an experimental investigation of a new solar desalination prototype using the humidification dehumidification principle at the weather conditions of Sfax City, Tunisia. The prototype is designed and constructed at the national engineering school of Sfax to conduct this experimental investigation under different meteorological and operating parameters. It is composed of a flat plate solar air collector, a flat plate solar water collector, a humidifier, an evaporation tower and a condensation tower. An economic analysis was conducted, since it affects the final cost of produced water, to determine both the cost of fresh water production and the payback period of the experimental setup. Although a system may be technically very efficient, it may not be economic. The experimental investigation of the dynamic behaviour of the solar desalination unit during summer season (June, July and August) and during a typical day in July was carried to study the temporal evolutions of the temperature of air and water and the relative humidity at the inlet and the outlet of each component of the system. © 2010 Elsevier Ltd. Source


Zargar S.,King Saud University
Saudi Journal of Biological Sciences | Year: 2014

Trigonella foenum-graecum belongs to the family Fabaceae and is indigenous to countries that lie on the eastern shores of the Mediterranean Sea and is also cultivated in India, Egypt and Africa. This study provides the evidence indicating the therapeutic effect of the extract prepared from the dried seeds of Trigonella foenum-graecum on an animal model of hepatotoxicity and on cell proliferation. Rats were induced liver cirrhosis by thioacetamide (0.03% in water for 16. weeks). Transmission electron microscopy of the liver tissue was done to evaluate liver cirrhosis. The herbal extract was administered orally for 3. weeks after induction and biochemical estimations were done. After the administration of extract the oxidative stress and lipid peroxidation were reversed. The elevated levels of alkaline phosphatase, γ-glutamyl transferase and selected biochemical markers of liver cirrhosis including drug metabolizing enzymes were also reversed. The study has implications in finding a treatment for liver cirrhosis by a natural herbal drug with no side effects. © 2013. Source


Al-Rejaie S.S.,King Saud University
Journal of Applied Pharmaceutical Science | Year: 2013

The present study has designed to investigate the effect of thymoquinone (THQ) on the status of hepatic oxidative stress and antioxidant defense system following ovariectomy (OVX) in Wistar rats. Animals were randomly assigned into five groups; sham, OVX and OVX+THQ treated groups in three doses (2.5, 5 and 10 mg/kg/day) orally by gavage for eight weeks. In serum, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels were estimated. In liver tissue, thiobarbituric acid reactive substances (TBARS), total glutathione (T-GSH), non-protein sulfhydryl groups (NP-SH) levels as well assuperoxide dismutase (SOD) and catalase (CAT) activities were also determined. Serum pre-oxidative markers (AST, ALT and ALP) were significantly increased in OVX rats compared to sham group. THQ inhibited these levels in a dose dependent manner. The lipid peroxidation product, TBARS, was significantly increased in OVX animals, which was inhibited by the THQ. In contrast, T-GSH and NP-SH levels were decreased in OVX rats, THQ treatments ameliorated these levels. Activities of SOD and CAT were significantly reduced in OVX group. THQ treatments significantly enhanced their activities in a dose dependent manner. The present results revealed the preventive effect of THQ on hepatic oxidative damage-induced by ovariectomy in rats. © 2013 Salim S. Al-Rejaie. Source


Jericho H.,King Saud University
Journal of Pediatric Gastroenterology and Nutrition | Year: 2016

ABSTRACT: Since the first description of celiac disease (CeD) by Samuel Gee in 1888 and the later “miraculous discovery” that bread was responsible for this condition following World War II in Europe there has been an exponential growth of knowledge regarding CeD. However, just when we thought that we knew everything there was to know about it, the disease is offering new challenges, with its presentaton having significantly morphed over the years from cases of overt gastrointestinal symptoms, malnutrition, and atrophic villi on duodenal biopsies to that of largely extra-intestinal, subtle or mild symptoms. Along with these changes, unexpectedly a new parallel entity appeared a few years ago and is gaining ground: the so-called non-celiac gluten sensitivity (NCGS), an improper name since it should actually be referred to as wheat intolerance syndrome (WIS) given that the role of gluten in all such cases is far from demonstrated and the implication of an immune involvement suggested by the term “sensitivity” is still unfounded. Lastly, wheat can be an offender also through an IgE mediated allergy, whose presence must also be evaluated and ruled out in selected cases.The practicing physician is therefore now challenged with the task of discerning which patients need to be assessed for one or the other of these disorders, and how.This review aims at providing an updated, critical reassessment of these two entities. © 2016 by European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology, Source


Al-Qattan M.M.,King Saud University
Annals of Plastic Surgery | Year: 2013

Preaxial polydactyly (PPD) is a common congenital abnormality and its classification varies among geneticists and hand surgeons. For example, the triphalangeal thumb, preaxial polysyndactyly, and the mirror hand deformity are considered as forms of PPD only in the genetics literature. Preaxial polydactyly is an error in the anteroposterior axis of the development of the upper limb. In this paper, the development of this axis is detailed and all molecular events that are known to lead to PPD are reviewed. Finally, based on the review, PPD is viewed as a spectrum of severity of embryonic events. Copyright © 2013 by Lippincott Williams & Wilkins. Source


El-Zaart A.,King Saud University
Computers in Biology and Medicine | Year: 2010

Breast cancer is among the leading causes of death in women worldwide. Mammography is the most effective imaging method for detecting no-palpable early-stage breast cancer. Understanding the nature of data in mammography images is very important for developing a model that fits well the data. Statistical distributions are widely used on the modelling of the data. Gamma distribution is more suitable than Gaussian distribution for modelling the data in mammography images. In this paper, we will use Gamma distribution to model the data in mammography images. The histogram of images can be seen as a mixture of Gamma distributions. Thresholds are selected at the valleys of a multi-modal histogram. The estimation of thresholds is based on the statistical parameters of the histogram. The expectation-maximization technique with gamma distribution (EMTG) is therefore developed to estimate the statistical histogram parameters. The experimental results on mammography images using this technique showed improvement in the accuracy in detection of the fibro-glandular discs. © 2010 Elsevier Ltd. Source


El-Azhary A.A.,King Saud University
Journal of Molecular Graphics and Modelling | Year: 2013

Conformational analysis was performed for 18-thiacrown-6 (18t6) using the CONFLEX method and the MMFF94s force field. Computations were performed for some of the low energy conformations at the HF, B3LYP, CAM-B3LYP, M06, M06L, M062x, M06HF and MP2 levels. The computations were also performed using the DFT-D3 method along with the TPSS and PBE functionals. The study predicted a new C 2 conformation as the ground state conformation of 18t6. This new C2 conformation is more stable than the experimentally known solid state conformation by 4.7 kcal/mol at the MP2/6-311G** level. This conformation has all of the SCCS dihedral angles adopt exodentate structure. However, the experimentally known conformation of the solid phase has two of the SCCS dihedral angles violating this exodentate rule. It was concluded that for 18t6 stability a linear dihedral SCCS angle requirement is more important than a gauche CSCC dihedral angle requirement. © 2013 Elsevier Inc. All rights reserved. Source


Zeitoun O.,King Saud University
Experimental Heat Transfer | Year: 2012

Flow visualization was used to measure hydraulic jump radius on a square plate. Heat transfer between a water jet and a horizontal square surface was investigated experimentally for different jets and square sizes. Effects of flow rates on heat transfer were investigated. The data are represented in terms of Nusselt number as a function of Reynolds and Peclet numbers. A correlation for the Nusselt number in terms of the Peclet number and L/D i was obtained. The proposed correlation predicts the current data of heat transfer very well. © 2012 Copyright Taylor and Francis Group, LLC. Source


The role of shoe wear on the tendency to slips and falls has been less studied than the contributions of floor surfaces to fall-related injuries. The purpose of this study was to better understand the principal aspects of shoe wear mechanisms and to identify the associated tribological characteristics of shoe/walking surface frictional behaviour. Dynamic friction tests were conducted amongst four types of shoes and two different floor specimens. Wear features and their development on the shoe surfaces were quantitatively and qualitatively examined before and after the tests. Test results showed that the initially unique micro- and macro-tread patterns experienced massive changes and severe damages. The worn surfaces of shoe heels acquired dissimilar wear shapes, sizes, and patterns. The main differences in their wear developments were strongly related to the material characteristics. Findings from this study provided new insights concerning the primary features of shoe wear such as abrasion patterns, crack formations, ruptures, structures, and damage propagation. The abrasion patterns of heel surfaces resulted from crack propagation at the root of the wear tongue and subsequent tearing of those tongues when they reached their maximum sizes. Wear behaviour of the shoe surfaces was significantly affected not only by the rate of crack propagation along a low angle of asperity slope, but also by the rate of crack propagation. Findings of this study may have potential applications to improve shoe designs for safer heels and soles. © 2016 Elsevier B.V. Source


Alzoghaibi M.A.,King Saud University
World Journal of Gastroenterology | Year: 2013

Oxygen free radical and lipid peroxides (oxidative stress) are highly reactive and represent very damaging compounds. Oxidative stress could be a major contributing factor to the tissue injury and fibrosis that characterize Crohn's disease. An imbalance between increased reactive oxygen species levels and decreased antioxidant defenses occurs in Crohn's patients. Decreased blood levels of vitamins C and E and decreased intestinal mucosal levels of CuZn superoxide dismutase, glutathione, vitamin A, C, E, and β-carotene have been reported for Crohn's patients. Increased levels of proinflammatory cytokines, such as interleukin-1 and -8 and tumor necrosis factor, have been detected in inflammatory bowel disease. Oxidative stress significantly increased the production of neutrophils, chemokines, and interleukin-8. These effects were inhibited by antioxidant vitamins and arachidonic acid metabolite inhibitors in human intestinal smooth muscle cells isolated from the bowels of Crohn's disease patients. The main pathological feature of Crohn's disease is an infiltration of polymorphonuclear neutrophils and mononuclear cells into the affected part of the intestine. Activated neutrophils produce noxious substances that cause inflammation and tissue injury. Due to the physiological and biochemical actions of reactive oxygen species and lipid peroxides, many of the clinical and pathophysiological features of Crohn's disease might be explained by an imbalance of increased reactive oxygen species and a net decrease of antioxidant molecules. This review describes the general concepts of free radical, lipid peroxide and antioxidant activities and eventually illustrates their interferences in the development of Crohn's strictures. © 2013 Baishideng. All rights reserved. Source


Al-Yahya M.,King Saud University
The Scientific World Journal | Year: 2014

With recent advancements in Semantic Web technologies, a new trend in MCQ item generation has emerged through the use of ontologies. Ontologies are knowledge representation structures that formally describe entities in a domain and their relationships, thus enabling automated inference and reasoning. Ontology-based MCQ item generation is still in its infancy, but substantial research efforts are being made in the field. However, the applicability of these models for use in an educational setting has not been thoroughly evaluated. In this paper, we present an experimental evaluation of an ontology-based MCQ item generation system known as OntoQue. The evaluation was conducted using two different domain ontologies. The findings of this study show that ontology-based MCQ generation systems produce satisfactory MCQ items to a certain extent. However, the evaluation also revealed a number of shortcomings with current ontology-based MCQ item generation systems with regard to the educational significance of an automatically constructed MCQ item, the knowledge level it addresses, and its language structure. Furthermore, for the task to be successful in producing high-quality MCQ items for learning assessments, this study suggests a novel, holistic view that incorporates learning content, learning objectives, lexical knowledge, and scenarios into a single cohesive framework. © 2014 Maha Al-Yahya. Source


Alhumaidi A.,King Saud University
Indian Journal of Dermatology, Venereology and Leprology | Year: 2012

Skin tumors are tumors arising from keratinocyte and from adnexal structures. Immunohistochemistry is very helpful in diagnosis of difficult cases in epithelial skin neoplasms, especially basal cell carcinoma (BCC) which is positive for BerEP4, a keratin marker, and mostly negative for epithelial membrane antigen (EMA). Squamous cell carcinoma cells are positive for EMA and cytokeratin, which are of higher molecular weight than those found in BCC. In contrast to BCC, trichoblastoma and trichoepithelioma are negative for androgen receptors. Of the malignant dermal spindle cell lesions, spindle cell squamous carcinoma is positive to 34 betaE12, desmoplasmic melanoma is positive to S100, and leiomyosarcoma is positive to desmin. Of the malignant pagetoid cells, Paget's disease is positive to CK7 and cam5.2, whereas the pagetoid variant of Bowen's disease is positive to CK 5/6. Melanoma in-situ is positive to both S100 and melan-A. Immunohistochemistry is an extremely valuable adjunct to standard morphologic diagnosis in diagnostic pathology. Diagnosis of epithelial tumor depends largely on morphological features but, in rare cases, immunohistochemical stains are needed for definitive diagnosis. Source


Khan M.I.,King Saud University | Siddique R.,Thapar University
Resources, Conservation and Recycling | Year: 2011

With increased environmental awareness and its potential hazardous effects, utilization of industrial byproducts has become an attractive alternative to disposal. Silica fume (SF), which is byproduct of the smelting process in the silicon and ferrosilicon industry. Silica fume is very effective in the design and development of high strength high performance concrete. This paper covers the physical, chemical properties of silica fume, and its reaction mechanism. It deals with the effect of silica fume on the permeability, freezing and thawing resistance, corrosion, sulfate resistance, carbonation, and alkali-aggregate resistance of concrete. © 2011 Elsevier B.V. All rights reserved. Source


Alhamad E.H.,King Saud University
Annals of Thoracic Medicine | Year: 2015

Background: Recent trials involving pirfenidone suggest a beneficial effect in the treatment of idiopathic pulmonary fibrosis (IPF). Objective: To report on the efficacy and safety of pirfenidone in the treatment of patients with IPF, at a tertiary care hospital in Saudi Arabia. Methods: The study included 58 patients with IPF who were evaluated from March 2012 to March 2013. During the study period, 33 patients received pirfenidone, and the remaining patients (n = 25) served as a control group. Baseline clinical characteristics, physiological parameters and the results of a 36-Item Short Form Health Survey (SF-36) were compared between the groups. Furthermore, we compared changes in forced vital capacity (FVC), diffusion capacity of the lung for carbon monoxide (DLco), six-minute walk distance (6MWD) and SF-36 for both groups during follow-up. The last follow-up period ended in January 2014. Results: There were no significant differences in baseline clinical characteristics between the groups. Furthermore, we found no differences in FVC, DLco and SF-36 during follow-up (median, 12 months). However, patients receiving pirfenidone treatment were less likely to experience reductions in 6MWD compared with the control group (13% vs. 52%, respectively; P = 0.001). Although adverse events were more frequently reported by the pirfenidone group compared with the control group (85 vs. 56%, respectively; P = 0.015), these patients did not require discontinuation of treatment. Conclusion: Pirfenidone treatment preserves functional capacity, as reflected by the 6MWD. Adverse events associated with pirfenidone treatment were generally well tolerated by the patients. Source


Omran W.A.,University of Waterloo | Kazerani M.,University of Waterloo | Salama M.M.A.,University of Waterloo | Salama M.M.A.,King Saud University
IEEE Transactions on Energy Conversion | Year: 2011

Photovoltaic (PV) systems are presently allowed to inject into the grid all the power they can generate. However, in the near future, utilities are expected to impose additional regulations and restrictions on the power being injected by large centralized PV systems because of their possible adverse impacts. One of the main issues associated with large PV systems is the fluctuation of their output power. These fluctuations can negatively impact the performance of the electric networks to which these systemsare connected, especially if the penetration levels of these systems are high. Moreover, the fluctuations in the power of PV systems make it difficult to predict their output, and thus, to consider them when scheduling the generating units in the network. The main objective of this paper is to investigate some methods that can be used to reduce the fluctuations in the power generated from a large customer-owned PV system, in the order of megawatts. This paper focuses on three methods: 1) the use of battery storage systems; 2)the use of dump loads; and 3) curtailment of the generated power by operating the power-conditioning unit of the PV system below the maximum power point. The emphasis in the analysis presented in this paper is on investigating the impacts of implementing these methods on the economical benefits that the PV system owner gains. To estimate the maximum revenues gained by the system owner, an linear programming optimization problem is formulated and solved. Moreover, the effect of varying different parameters of the problem is investigated through sensitivity analysis. © 2010 IEEE. Source


El-Kady M.A.,King Saud University
IET Generation, Transmission and Distribution | Year: 2011

AC distribution factors have been used extensively in the recent power and energy pricing studies in free electricity market environment. Because the AC power flow in a given transmission line depends on the complex voltage value at the point of calculation along the line, distribution factors relating line flows to bus injected powers would also depend on such point of calculation. In open-market pricing studies, more flexibility is needed in the derivation and use of power distribution factors in order to allow market entities to base their calculated line flows on a reference (point of calculation) of their market contractual choice. This paper presents a novel model for evaluating universal distribution factors, which are suitable for a wide range of power system analysis and electricity market pricing studies. These universal distribution factors are compact matrix-form expressions with total flexibility in defining the position on the line at which line flows are measured. They are independent of bus power injections and, therefore, can be used for analyzing different pricing scenarios involving different bus power contributions. The paper also demonstrates the practical calculation of the universal distribution factors as well as their sensitivities with respect to the line voltage profile. © 2011 The Institution of Engineering and Technology. Source


Swarbrick H.A.,University of New South Wales | Alharbi A.,King Saud University | Watt K.,University of New South Wales | Lum E.,University of New South Wales | Kang P.,University of New South Wales
Ophthalmology | Year: 2015

Purpose To investigate the effect of overnight orthokeratology (OK) contact lens wear on axial length growth in East Asian children with progressive myopia. Design A prospective, randomized, contralateral-eye crossover study conducted over a 1-year period. Participants We enrolled 26 myopic children (age range, 10.8-17.0 years) of East Asian ethnicity. Methods Subjects were fitted with overnight OK in 1 eye, chosen at random, and conventional rigid gas-permeable (GP) lenses for daytime wear in the contralateral eye. Lenses were worn for 6 months. After a 2-week recovery period without lens wear, lens-eye combinations were reversed and lens wear was continued for a further 6 months, followed by another 2-week recovery period without lens wear. Axial eye length was monitored at baseline and every 3 months using an IOLMaster biometer. Corneal topography (Medmont E300) and objective refraction (Shin-Nippon NVision-K 5001 autorefractor) were also measured to confirm that OK lens wear was efficacious in correcting myopia. Main Outcome Measurements Axial length elongation and myopia progression with OK were compared with conventional daytime rigid contact lens wear. Results After 6 months of lens wear, axial length had increased by 0.04±0.06 mm (mean ± standard deviation) in the GP eye (P = 0.011) but showed no change (-0.02±0.05 mm) in the OK eye (P = 0.888). During the second 6-month phase of lens wear, in the OK eye there was no change from baseline in axial length at 12 months (-0.04±0.08 mm; P = 0.218). However, in the GP eye, the 12-month increase in axial length was significant (0.09±0.09 mm; P < 0.001). The GP lens-wearing eye showed progressive axial length growth throughout the study. Conclusions These results provide evidence that, at least in the initial months of lens wear, overnight OK inhibits axial eye growth and myopia progression compared with conventional GP lenses. Apparent shortening of axial length early in OK lens wear may reflect the contribution of OK-induced central corneal thinning, combined with choroidal thickening or recovery due to a reduction or neutralization of the myopiogenic stimulus to eye growth in these myopic children. © 2015 American Academy of Ophthalmology. Source


Del Sorbo L.,University of Turin | Slutsky A.S.,University of Toronto | Slutsky A.S.,King Saud University
Current Opinion in Critical Care | Year: 2011

Purpose of Review: Despite improvements in outcome due to lung protective ventilation strategies using low tidal volumes, the mortality rate from acute respiratory distress syndrome (ARDS) remains unacceptably high, ranging from 34 to 64%. The predominant cause of death in ARDS is not severe hypoxemia, which is one of the defining criteria of ARDS, but multiple organ failure (MOF). Recent Findings: In view of the relationship between ARDS and MOF, two different but complementary pathophysiological perspectives will be developed in this article: ARDS as a consequence of MOF, and ARDS as the cause of MOF. This framework may be useful in guiding the development of novel therapeutic strategies that ultimately improve the outcome of ARDS and sepsis patients. Summary: ARDS is a severe lung disease characterized by a very complex pathophysiology, involving not only the respiratory system but also nonpulmonary distal organs. Elucidation of the pathophysiological mechanisms bi-directionally linking MOF to ARDS appears to be a promising area of research that hopefully will lead to improved outcomes for these devastating conditions. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source


Al-Qattan M.M.,King Saud University
Annals of Plastic Surgery | Year: 2013

Fanconi anemia is known to be associated with radial ray deficiency (thumb and radius hypoplasia), and its embryological basis remains to be poorly understood. We describe a rare case of Fanconi anemia with concurrent thumb polydactyly and dorsal dimelia. The embryological basis of limb abnormalities in Fanconi anemia patients is thought to be based on the complex interactions between the apical ectodermal ridge (where Fanconi anemia genes are expressed) and both the mesoderm (where Spalt-like 4 (SALL4) and Sonic hedgehog (SHH) are located and which are responsible for radial ray deficiency, thumb polydactyly, and triphalangism) and the dorsoventral axis (an error in that axis leads to dorsal dimelia). Copyright © 2012 by Lippincott Williams & Wilkins. Source


Status epilepticus (SE), one of the most severe forms of epilepsy is regarded a medical emergency with considerable morbidity and mortality. Due to the limited efficacy and enormous side effects of currently available drugs, a search for new safe and effective therapeutic agents is critical using experimentally induced SE in animals. The lithium-pilocarpine (Li-Pc) model of SE is most suitable and frequently used for pathophysiological and management strategies of SE. Recent studies have shown significant potential of pharmacological, prophylactic or therapeutic use of curcumin (Cur) in many beneficial activities in the body including neuroprotection in neurodegenerative diseases and antioxidant properties. The present study describes anticonvulsive effects of Cur in Li-Pc induced SE in young rats. The effect of Cur was examined on the intensity and frequency of SE, cognitive behavior in water maze as well as on oxidative stress related enzymes in the brain. Besides its anticonvulsant effect, Cur significantly ameliorates SE-induced cognitive dysfunction and oxidative damages in the hippocampus and striatum areas of the brain. Possible therapeutic application of Cur as an anticonvulsant and as an antioxidant for the treatment of SE has a great potential and warrants further studies. © 2013. Source


Ahmed A.M.,King Saud University
Pakistan Journal of Zoology | Year: 2013

This study was conducted to investigate the oxidative stress and apoptotic signs detectable by flow cytometry as proposed pathogenicity mechanisms for the mosquitocidal bacterium Bacillus thuringiensis (Bt) in the mosquito vector, Culex pipiens. Obtained data showed elevation in the levels of the oxidative stress biomarkers, the lipid peroxidation and protein oxidation, upon Bt-infection. Larvae showed significant higher levels of both lipid peroxidation and protein oxidation at 12 and 24h post-infection compared to control ones. In addition, Bt-inoculated adult mosquitoes also showed significant higher lipid peroxidation at 12 and 24h post-inoculation compared to control ones. These signs of oxidative stress were more pronounced in bacterial infected larvae than in bacterial inoculated adult mosquitoes. Finally, Bt-infected larvae showed significant higher percentages of cellular apoptosis at 12 an 24h post-infection compared to control ones. These data may indicate that Bt infection induced oxidative stress and apoptosis proceeding cellular damage, and thus, may be suggested as important pathogenicity mechanisms of Bt in its mosquito host. And hence, these data may participate in improving our understanding of the mosquito-Bt interaction scenario, which may help improving the biocontrol measurements against mosquito vectors. Copyright 2013 Zoological Society of Pakistan. Source


With their unique physicochemical properties, single walled carbon nanotubes (SWCNTs) hold great promise for applications as drug delivery systems (DDS) for early and better diagnosis and therapy of cancer. While several in vitro and in vivo studies have validated their potential benefit, no SWCNT-based formulation has yet reached clinical trials. Towards prospective safe clinical applications, the main properties that were adopted to enhance the biocompatibility of SWCNTs were highlighted. Then, the recent progresses in the in vivo applications of SWCNTs as diagnostic nanoprobes using multimodality imaging techniques and as therapeutic nanocarriers delivering wide range of anticancer efficient drugs to tumors were reviewed. Finally, the efforts required for safe clinical applications of SWCNTs as DDS for cancer diagnosis and therapy were discussed. © 2016 Future Medicine Ltd. Source


Alharbi S.R.S.,King Saud University
Annals of Thoracic Medicine | Year: 2013

Gastrobronchial fistula is a rare but serious complication of laparoscopic sleeve gastrectomy with significant morbidity and mortality. We present the case of a 30-year-old man who underwent laparoscopic sleeve gastrectomy for morbid obesity and presented later with a history of chronic productive cough. Upper gastrointestinal series showed the presence of a communicating fistula between the stomach and the left lung bronchial tree. Source


El-Sherbiny M.M.,Cairo University | Alhamali R.M.,King Saud University
Computers and Industrial Engineering | Year: 2013

Fixed Charge Transportation Problem (FCTP) is an NP-hard problem with many applications in both traditional and modern industrial situations. This paper introduces a Hybrid Particle Swarm algorithm with artificial Immune Learning (HPSIL) for solving fixed FCTPs. In HPSIL algorithm a flexible particle (chromosome) structure, decoding procedure and allocation procedure are used instead of a Prüfer number and a spanning tree that used with genetic algorithms. The proposed allocation procedure guarantees finding a feasible solution for each generated particle. The HPSIL algorithm can be used for solving both balanced and unbalanced FCTPs without introducing dummy supplier or dummy demand. With regard to solution quality, the HPSIL algorithm can be considered as a viable alternative for solving FCTPs in addition to the recent algorithms. © 2012 Elsevier Ltd. All rights reserved. Source


Al-Saleh A.M.,King Saud University
Arabian Journal of Geosciences | Year: 2010

A number of gneiss-cored domes and antiforms are exposed along the regional strike-slip Najd fault system in the Arabian Shield and the eastern desert of Egypt. The mode of origin is still controversial, although plausible comparisons with modern metamorphic core complexes were made in some well-studied areas. The Kirsh dome is located within the major Ar Rika shear zone and consists of a core of orthogneiss/migmatite and an envelope of paragneisses with locally abundant kyanite-bearing quartzites. The dome is surrounded by the low-grade metasediments of the Murdama Group and is bound from the south by a lowangle dip-slip fault. Beyond the southern strand of the Ar Rika Fault is the Kibdi Basin which hosts unmetamorphosed sediments belonging to the Jibalah Group; this group occupies scattered pull-apart basins closely associated with releasing bends along the Najd fault system. Little dating has been done on the gneiss domes of the Arabian Shield; however, recent dates from similar structures in the eastern desert and Sinai range from 580 to 620 Ma. A similar, albeit younger 40Ar/39Ar age of 557±15 Ma was obtained from a biotite paragneiss south of Jabal Kirsh; this age difference probably represent the time interval it took the Kirsh rocks to cool below the biotite closure temperature and would place a lower age limit for the dome. The Kirsh dome occupies an extensional zone between left-stepping faults; movement within this zone might have caused enough decompression to trigger fluidabsent melting in the middle crust especially as the rocks cross the biotite dehydration solidus. Diapiric ascent aided by strike-slip dilatancy pumping led to the emplacement of the Kirsh rocks in their present position within the Murdama Group metasediments. ©Saudi Society for Geosciences 2010. Source


Edel K.H.,University of Munster | Kudla J.,University of Munster | Kudla J.,King Saud University
Cell Calcium | Year: 2015

Calcium serves as a versatile messenger in adaptation reactions and developmental processes in plants and animals. Eukaryotic cells generate cytosolic Ca2+ signals via Ca2+ conducting channels. Ca2+ signals are represented in form of stimulus-specific spatially and temporally defined Ca2+ signatures. These Ca2+ signatures are detected, decoded and transmitted to downstream responses by an elaborate toolkit of Ca2+ binding proteins that function as Ca2+ sensors.In this article, we examine the distribution and evolution of Ca2+-conducting channels and Ca2+ decoding proteins in the plant lineage. To this end, we have in addition to previously studied genomes of plant species, identified and analyzed the Ca2+-signaling components from species that hold key evolutionary positions like the filamentous terrestrial algae Klebsormidium flaccidum and Amborella trichopoda, the single living representative of the sister lineage to all other extant flowering plants.Plants and animals exhibit substantial differences in their complements of Ca2+ channels and Ca2+ binding proteins. Within the plant lineage, remarkable differences in the evolution of complexity between different families of Ca2+ signaling proteins are observable. Using the CBL/CIPK Ca2+ sensor/kinase signaling network as model, we attempt to link evolutionary tendencies to functional predictions. Our analyses, for example, suggest Ca2+ dependent regulation of Na+ homeostasis as an evolutionary most ancient function of this signaling network. Overall, gene families of Ca2+ signaling proteins have significantly increased in their size during plant evolution reaching an extraordinary complexity in angiosperms. © 2014 Elsevier Ltd. Source


Attiya A.M.,King Saud University
Progress In Electromagnetics Research M | Year: 2010

Shift-Operator Finite difference Time Domain (SO-FDTD) method is introduced as a new efficient technique for simulating electromagnetic wave interaction with chiral medium. The dispersive properties of this medium are presented as polynomials of jw. These polynomials are converted to time domain by replacing jw by the time derivative operator. Then this time derivative operator is converted to the corresponding time shift operator which is used directly to obtain the corresponding update equations of electric and magnetic field components. The resulting update equations do not require time convolution or additional vector components. The present analysis does not require also any transformation. Significant improvement is obtained in memory requirements by using this method while the computational time is nearly the same compared with other similar techniques like Z-transformation FDTD. Source


Al-Khalifa H.S.,King Saud University
Universal Access in the Information Society | Year: 2012

This study is intended to provide an exploratory evaluation of Saudi Arabia government Web sites based on the Web Accessibility Guidelines 2.0 provided by the W3C. The results indicate that the Saudi government Web sites have made many of the accessibility mistakes as predicted. In the light of the study findings, this paper will present some recommendations for improving Saudi government Web sites, as well as discuss future implications. © 2010 Springer-Verlag. Source


Batayneh A.T.,King Saud University
International Journal of Physical Sciences | Year: 2010

The objective of this study is to determine the seasonal water quality variations of the major springs of the Yarmouk Basin of North Jordan. A total of 36 water samples were collected in October 2006 (dry season) and in May 2007 (wet season) and analyzed for temperature, electrical conductivity, total dissolved solids, pH, Pb, Cd, Zn, Cu, Mn and Fe. The pH was found near alkaline ranging from 7.01 - 7.87 and 6.8 - 8.04 for the pre and post-wet season water samples, respectively. Electrical conductivity varied from 300 to 1199 μS/cm and from 424 to 962 μS/ cm for the dry and wet season water samples, respectively. The results of heavy metals analysis indicated that some water samples exceeded the Jordanian. Overall, the results showed that the water springs of the Yarmouk Basin in North Jordan are contaminated with heavy metals that might affect human health as well as the health of the ecosystem. © 2010 Academic Journals. Source


Al-Rubeaan K.,King Saud University
Journal of Epidemiology and Community Health | Year: 2015

Background There is a paucity of data on the national prevalence of diabetes and prediabetes among youth. The Saudi Abnormal Glucose Metabolism and Diabetes Impact Study (SAUDI-DM) was used to assess the prevalence of type 1 and type 2 diabetes as well as impaired fasting glucose (IFG) among children and adolescents. Methods Sociodemographic, anthropometric and clinical data were collected through a nationwide household randomly selected 23 523 children and adolescents aged ≤18 years. Known participants with diabetes were classified according to their diabetes type, while participants without diabetes were subjected to fasting plasma glucose assessment and patients with diabetes were identified using the American Diabetes Association (ADA) criteria. All the studied participants were tested for lipid parameters. Multivariate logistic regression analysis was used to assess different risk factors. Results The overall prevalence of diabetes was 10.84%, of which 0.45% were known type 1 and type 2 patients with diabetes and 10.39% were either newly identified cases of diabetes (4.27%) or IFG (6.12%) with more than 90% of the participants with diabetes being unaware of their disease. The prevalence of known type 1 and type 2 diabetes as well as the newly identified cases was higher than what has been reported internationally. Age, male gender, obesity, urban residency, high family income and presence of dyslipidaemia were found to be significant risk factors for diabetes and IFG. Conclusions Diabetes and IFG are highly prevalent in this society with the majority of the patients being unaware of their disease, which warrants urgent adoption of early detection, treatment and prevention programmes. Source


This study was designed to investigate the effect of butylated hydroxy toluene (BHT), a phenolic antioxidant used in foods, cosmetics and pharmaceutical products, on Fe-NTA-induced nephrotoxicity in rats. Fe-NTA (alone) treatment enhances ornithine decarboxylase activity to 5.3-fold, and [3H] thymidine incorporation in DNA to 3.5-fold compared with the corresponding saline treated control. The enhanced ornithine decarboxylase activity and DNA synthesis showed a reduction to 2.12-2.15-fold respectively at a higher dose of 2mg BHT/day/animal, compared with the Fe-NTA treated group. Fe-NTA treatment also enhanced the renal microsomal lipid peroxidation to 2.0-fold and decreased the activities of glutathione and antioxidant enzymes to a range of 2.2-2.5-fold in kidney. These changes were reversed significantly in animals receiving a pretreatment of BHT. Present data suggests that BHT can prevent the toxic effects of Fe-NTA and can serve as a potent chemopreventive agent to suppress oxidant-induced tissue injury and nephrotoxicity in rats. © 2013 Elsevier Ltd. Source


Pasolli E.,University of Trento | Melgani F.,University of Trento | Bazi Y.,King Saud University
IEEE Geoscience and Remote Sensing Letters | Year: 2011

Active learning is showing to be a useful approach to improve the efficiency of the classification process for remote sensing images. This letter introduces a new active learning strategy specifically developed for support vector machine (SVM) classification. It relies on the idea of the following: 1) reformulating the original classification problem into a new problem where it is needed to discriminate between significant and nonsignificant samples, according to a concept of significance which is proper to the SVM theory; and 2) constructing the corresponding significance space to suitably guide the selection of the samples potentially useful to better deal with the original classification problem. Experiments were conducted on both multi- and hyperspectral images. Results show interesting advantages of the proposed method in terms of convergence speed, stability, and sparseness. © 2010 IEEE. Source


Al-Dosari M.S.,King Saud University
American Journal of Chinese Medicine | Year: 2012

The present study was conducted to determine whether lyophilized aqueous extract of alfalfa, or Medicago sativa L. could exert antioxidant activity against carbon tetrachloride-induced oxidative stress and liver injury in rats. The hepatoprotective activity of alfalfa extract was determined by assessing the levels of serum transaminases, ALP, bilirubin and lipid profile. Further, the effect of the test substance on malondialdehyde (MDA), an end product of lipid peroxidation; antioxidant liver enzyme non-protein sulfhydryl (NP-SH); and total protein (TP) were also studied. Serum transaminase, ALP, bilirubin level, lipid profile and liver MDA were significantly elevated and the antioxidant status in liver NP-SH and TP contents were declined in animals treated with CCl 4 alone. Pretreatment with alfalfa and silymarin for three weeks prior to the administration of CCl 4 significantly prevented the increase in the serum levels of hepatic marker, LDL, VLDL levels enzymes and reduced oxidative stress indicated by elevated NP-SH and TP concentration. The histopathological examination of the livers also showed that the alfalfa extract reduced the incidence of liver lesions induced by CCl 4. The in vitro antioxidant assessment of alfalfa extract on DPPH and carotene-linoleic assays demonstrated a moderate antioxidant potential. Results suggest that the alfalfa extract possesses hepatoprotective and antioxidative stress properties possibly through its antioxidant phytochemical constituents and substantiates its use in various liver disorders as a hepatoprotector. © 2012 World Scientific Publishing Company & Institute for Advanced Research in Asian Science and Medicine. Source


El Hindi K.,King Saud University
AI Communications | Year: 2013

The classification accuracy of many machine learning methods depends upon their ability to accurately measure the similarity between different instances. Similarity is measured using a distance metric or measure. In this work, several novel distance measures for nominal values are proposed. These distance measures exploit the class of a training example against which a new instance is compared. The experiments, conducted using 50 benchmark data sets, indicate that the proposed functions are superior in many cases to the Value Difference Metric (VDM) that is widely used in instance based learning. Some of the proposed measures have proven to be less sensitive to missing values and noise in the training data sets and have maintained good classification accuracy in the presence of unknown and noisy attribute values. Like VDM, the proposed measures work only with labelled training data sets which makes them unsuitable for unsupervised learning methods. © 2013 - IOS Press and the authors. All rights reserved. Source


Dyab A.K.F.,Minia University | Atta A.M.,King Saud University
RSC Advances | Year: 2013

Non-aqueous emulsions with a high storage stability are stabilised with organic solvent-borne crosslinked poly(N-isopropylacrylamide-co-2-acrylamido-2- methylpropane sulfonic acid) poly(NIPAM-co-AMPS) microgels functionalised with a nonionic polymerisable surfactant (polyoxyethylene 4-nonyl-2-propyl-phenyl maleate ester). The oil-oil interfacial tensions are reduced to unprecedented values by the newly prepared microgels. © 2013 The Royal Society of Chemistry. Source


Morsy M.H.,King Saud University
Energy Conversion and Management | Year: 2015

Enhancing the combustion process of today's diesel engines necessitates finding practical methods to reduce harmful emissions, with minor modifications on the main structure of the engine. Dual fuel method has been recognized as an effective way that be able to resolve the emissions problems encountered in diesel engines and attain higher performance. An experimental investigation is performed to explore the effects of using ethanol/water mixtures fumigation into the inlet air on the performance and exhaust emissions of a fully instrumented single cylinder diesel engine. Ethanol/water with different mixing ratios (25%, 50%, 75% and 100% by volume) are used as a secondary fuel with diesel as the main fuel. Fuel consumption, exhaust gas temperatures and exhaust emissions such as nitrogen oxides, carbon monoxide and unburned hydrocarbons are measured and compared for both methods of operation. In addition, thermal and exergy efficiencies are calculated and compared. The results indicated that NO emission tend to decrease with mixtures containing water and tend to slightly increase with pure ethanol fumigation. CO, HC emissions and fuel consumption tend to increase while exhaust gas temperatures tend to decrease with all mixtures of ethanol/water fumigation. Slight improvements in thermal and exergy efficiencies with ethanol/water mixtures fumigation are found. Results confirmed the potential use of ethanol/water fumigation in diesel engines for better energy and exergy efficiencies and lower NO emission. © 2015 Elsevier Ltd. All rights reserved. Source


Ambigaipalan P.,Memorial University of Newfoundland | Al-Khalifa A.S.,King Saud University | Shahidi F.,Memorial University of Newfoundland
Journal of Functional Foods | Year: 2015

Date seed flour was used to produce protein hydrolysates using Alcalase (AL), Flavourzyme (FL) and Thermolysin (TH). Enzymes were used individually or in combination at a constant pH and temperature. The degree of hydrolysis ranged between 11 and 14%. The molecular weights of peptides determined, using a quadrupole orthogonal time-of-flight hybrid tandem mass spectrometer, ranged from 2062.9 ± 0.0 to 116,803.8 ± 0.4 Da. AL hydrolysate showed the lowest reducing power and ABTS radical scavenging activity, but a higher ACE inhibition and hydroxyl radical scavenging. Among all treatments, hydrolysates prepared using a combination of AL and FL exhibited the highest reducing power and metal chelation and high scavenging for ABTS, DPPH, hydroxyl radicals as well as ACE inhibitory activity. Combinations of AL and TH exhibited the highest ACE inhibitory activity with an IC50 value of 0.53 mg/mL. These results indicate that date seed protein hydrolysate could be used as a potential health promoting ingredient with antioxidant and ACE inhibitory activities. © 2015 Elsevier Ltd. Source


Weidman P.D.,University of Colorado at Boulder | Ali M.E.,King Saud University
European Journal of Mechanics, B/Fluids | Year: 2011

Laminar radial stagnation flow impinging on a stretching or shrinking elastic cylinder of radius a is studied. The strain rate of the stagnation flow is 2k and that of the stretching cylinder is b. The origin of stretching is in general displaced by a distance c from the inviscid stagnation circle on the cylinder. An exact similarity reduction of the NavierStokes equations leads to coupled ordinary differential equations describing the primary flow f(η) and a secondary flow g(η) with similarity variable η=(ra)2. The system is governed by the Reynolds number R=ka22ν, the dimensionless offset parameter α=ca, and the dimensionless stretching parameter β=b2k, where ν is the kinematic viscosity of the fluid. Solutions of the coupled equations only depend on R and β, but the flow field depends crucially on α. Analytic solutions are found for the special values R=2+β and also for all β if R=1. For other values of R and β, solutions are obtained numerically. We find no solutions for β<βc, dual solutions when βc≤β<-1, and unique solutions for β>-1, where βc depends on R. The stability of the dual primary flow solutions is determined and the effect of flow misalignment is displayed in streamfunction plots. © 2010 Elsevier Masson SAS. All rights reserved. Source


Mammalian GIB-PLA2 are well characterized. In contrast, much less is known about aquatic ones. The aquatic world contains a wide variety of living species and, hence represents a great potential for discovering new lipolytic enzymes. The aim of this study was to check some biochemical and structural properties of a marine stingray phospholipase A2 (SPLA2). The effect of some proteolytic enzymes on SPLA2 was checked. Chymotrypsin and trypsin were able to hydrolyze SPLA2 in different ways. In both cases, only N-terminal fragments were accumulated during the hydrolysis, whereas no C-terminal fragment was obtained in either case. Tryptic and chymotryptic attack generated 13 kDa and 12 kDa forms of SPLA2, respectively. Interestingly, the SPLA2 13 kDa form was inactive, whereas the SPLA2 12 kDa form conserved almost its full phospholipase activity. In the absence of bile slats both native and 12 kDa SPLA2 failed to catalyse the hydrolysis of PC emulsion. When bile salts were pre-incubated with the substrate, the native kinetic protein remained linear for more than 25 min, whereas the 12 kDa form activity was found to decrease rapidly. Furthermore, The SPLA2 activity was dependent on Ca 2+; other cations (Mg 2+, Mn 2+, Cd 2+ and Zn 2+) reduced the enzymatic activity notably, suggesting that the arrangement of the catalytic site presents an exclusive structure for Ca 2+. Although marine and mammal pancreatic PLA2 share a high amino acid sequence homology, polyclonal antibodies directed against SPLA2 failed to recognize mammal PLA2 like the dromedary pancreatic one. Further investigations are needed to identify key residues involved in substrate recognition responsible for biochemical differences between the 2 classes of phospholipases. Source


Azmi A.M.,King Saud University
Information Sciences | Year: 2016

A primitive tandem repeat α is a substring in string S if it can be expressed as two or more contiguous copies of β, where the base β cannot be expressed in terms of yet a shorter substring. Substring α is maximal if there is no copy of β to either its left or right. Tandem repeats (or arrays) are known to play an important role in biology, e.g. determining parentage. We present a deterministic algorithm that finds all the exact primitive maximal tandem arrays that occur in S, where at iteration k it discovers all the repeats with base length k. Our algorithm uses a simple list structure for all its operations. In theory, the algorithm scales well with the size of the alphabet. For strings over the alphabet Σ it has a complexity of O(|S|+|Σ|) in space, and O(B|S|-B2/2) in time, where B is the length of the longest primitive base of a tandem repeat in S. Experimental results on real biological sequences, randomly generated sequences using large sized alphabets, and Fibonacci strings, show that in practice the algorithm has indeed a linear complexity, both in space and time. © 2016 Elsevier Inc. All rights reserved. Source


Hassan E.S.A.,King Saud University
Journal of Sports Medicine and Physical Fitness | Year: 2011

Aim. In this study the application of cold water (CW) or warm water (WW) for the recovery delayed onset muscle soreness (DOMS) was investigated in comparison with a control group without the application of water (CO) after eccentric exercise. Methods. The main study took place in a randomized, controlled study design on 60 healthy, moderately athletic young men (aged 22 years), classified into 3 groups with 20 men per group. The load was equivalent to the 70% of 1 RM, one-repetition maximum at the Deadlift (Bent Leg). Exercise consisted of 10 sets of 10 eccentric contractions of the Hamstrings muscle group after which they were exposed to either CW (20° C), or WW (38 °C) or no intervention at all (CO). Blood samples were taken 30min before, after and 1, 2 and 6 hours after performing the exercise. Results. The exercise showed to a clear increase in the muscle stress parameters without significant difference in results between the groups. The application of WW after exercise resulted in a prominent decrease in muscle cell reaction. In addition, a significant decrease was noticed in the skeletal troponin I (sTnl), creatin kinase (CK) and myoglobin (Mb) after ww. Conclusion. These results are indicative that the exposure of CW (20 °C/30 min) after exercise would lead to an elevated muscle cells stress reaction. On the other hand exposure to WW (38 °C/30 min) leads to a decrease in the exercise-induced deflection of muscle cell reaction. Source


Mahmoud S.H.,King Saud University
Environmental Earth Sciences | Year: 2014

In arid and semi-arid regions without perennial water sources such as rivers or lakes, almost all water supply needs are met by groundwater. Groundwater recharge (GWR) is critical to maintain the abundance of groundwater. This paper presents a methodology based on a decision support system (DSS) that combines remote sensing, field survey and geographic information system techniques to identify suitable GWR areas. The DSS was implemented to obtain suitability maps and to evaluate the existing GWR in the study area. The DSS inputs comprised maps of rainfall surplus, slope, potential runoff coefficient, land cover/use and soil texture. The spatial extents of GWR suitability areas were identified by a hierarchical process analysis that considered five layers. The model generated a GWR map with four categories of suitability: excellent, good, moderate and poor and unsuitable. The spatial distribution of these categories showed that 0.08 and 32.3 % of the study area was classified as excellent and good for GWR, respectively, while 63.2 and 4.42 % of the area was classified as moderate and poor and unsuitable, respectively. Most of the areas with excellent to good suitability have slopes of between 4 and 8 % and are intensively cultivated areas. The major soil type in the excellent to good areas is loam, followed by clay loam, and the rainfall in these areas ranges from 150 to 260 mm. Another suitability model, in which all criteria were assigned equal influence, generated a suitability map in which 0.1 % of the study area was rated as excellent, 10.9 % as good, 82 % as moderate and 7 % as poor and unsuitable. The locations of existing GWR dams were compared with the locations indicated on the generated suitability map using the proximity analysis tool in ArcGIS 10.1. Most (77 %) of the existing GWR structures that were categorised as successful were within the excellent and good areas, followed by moderately suitable (23 %). © 2014, Springer-Verlag Berlin Heidelberg. Source


Askar A.M.,King Saud University
Saudi Medical Journal | Year: 2015

Hyperphosphatemia is a major cause of morbidity and mortality in patients with chronic kidney disease. The association between hyperphosphatemia and increased risk of death from cardiovascular disease/vascular calcification has been well established for a long time. This review explores the new aspects of pathogenesis of vascular calcification, as demonstrated by recent advances showing a recognized regulating role of phosphorus in vascular smooth muscle cell calcification. This novel mechanism may help in finding a new pharmacological therapy to reduce, or prevent blood vessel calcification. Furthermore, recent experimental and clinical studies involved in the treatment of hyperphosphatemia are reviewed in this article. © 2015 Saudi Arabian Armed Forces Hospital. All rights reserved. Source


Abu El-Asrar A.M.,King Saud University
Discovery medicine | Year: 2010

Diabetic retinopathy, the most common long-term complication of diabetes mellitus, remains one of the leading causes of blindness worldwide. Strict metabolic control, tight blood pressure control, laser photocoagulation, and vitrectomy remain the standard care for diabetic retinopathy. Focal/grid photocoagulation is a better treatment than intravitreal triamcinolone acetonide in eyes with diabetic macular edema and should be considered as the first-line therapeutic option. The current evidence suggests that intravitreal triamcinolone acetonide or anti-vascular endothelial growth factor agents result in a temporary improvement of visual acuity and a short-term reduction of central macular thickness in patients with refractory diabetic macular edema and are effective adjunctive treatment to laser photocoagulation or vitrectomy. However, triamcinolone is associated with risks of elevated intraocular pressure and cataract. Vitrectomy with removal of the posterior hyaloid without internal limiting membrane peeling seems to be effective in eyes with persistent diffuse diabetic macular edema, particularly in eyes with associated vitreomacular traction. Emerging therapies include islet cell transplantation, fenofibrate, ruboxistaurin, pharmacologic vitreolysis, rennin-angiotensin system blockers, and peroxisome proliferator-activated receptor gamma agonists. Source


Hariga M.A.,American University of Sharjah | Al-Ahmari A.,King Saud University
Computers and Industrial Engineering | Year: 2013

Abstract In this paper, we develop integrated retail shelf space allocation and inventory models for a single item with a stock dependent demand. The integrated models are developed for a supply chain operating under vendor-managed inventory (VMI) and consignment stock (CS) agreement. More precisely, the supplier is responsible for initiating orders on behalf of the retailer and decides about the size of each order, the quantity to be displayed on the shelves, and the reorder point. In addition, the supplier owns the stock at the retailer's premises until it is sold. We develop mathematical models to assess the benefits accrued by both parties as a result of the adoption of VMI-CS partnership. Results from the numerical experimental study show that such partnership is more attractive to all supply chain members when the retailer provides a flexible display capacity. Moreover, the supplier can use his/her selling price and the maximum allocated shelf space as negotiation means to benefit from the partnership. © 2012 Elsevier Ltd. All rights reserved. Source


Al-Qattan M.M.,King Saud University
Journal of Hand Surgery: European Volume | Year: 2011

The various Wnt pathways that are related to upper limb anomalies are reviewed. Abnormalities in the Wnt7a pathway (located in the dorsal ectoderm) produce several clinically relevant conditions such as the palmar duplication syndrome, nail patella syndrome, ulnar ray deficiency, limb hypoplasia, polysyndactyly and the palmar nail syndrome. Abnormalities of the Wnt3/3a pathway (located in the apical ectodermal ridge) include tetra-amelia and loss of the distal phalanges/nails. Abnormalities of the Wnt5/5a pathway (located in the apical ectodermal ridge as well as in the mesoderm) will affect chondrogenesis of the developing limb and experimental Wnt5a-/- limbs have terminal adactyly. Chondrogenesis and limb muscle differentiation are both affected by several Wnt pathways and these will be reviewed in details. Abnormalities in LRP 5/6 (a co-receptor for Wnts) lead to congenital bone disease and Wnt4 is specifically involved in joint development. Finally, the relationship between the Wnt pathway and SALL4 (mutations of which cause Okihiro/Duane-radial ray deficiency in humans) are discussed. Source


Reedijk J.,Leiden University | Reedijk J.,King Saud University
Metallomics | Year: 2012

The binding of transition metal compounds to nucleic acids is discussed in the perspectives of kinetics and their anticancer activity. Kinetics of ligand exchange is primarily determined by the intrinsic properties of the metal ions, and to a lesser degree by the ligands coordinated already to the metal ion. Metal compounds having ligand-exchange rates of the same order of magnitude as cell-division processes, e.g. many Pt(ii), Ru(ii) and Ru(iii) compounds, are in use as chemotherapeutic drugs. Detailed knowledge of ligand exchange in such compounds is important for design of derivative and entirely new compounds. Metal coordination compounds of metal ions with much faster ligand-exchange reactions interact with DNA in a quite different way, namely primarily by compensation of negative charge of the polyanionic chain and are usually not active as anticancer agents. Examples of our recent work are presented in relation with experiments performed by others on new generations of platinum anti-cancer drugs. This journal is © 2012 The Royal Society of Chemistry. Source


Background: Understanding surface anatomy and surface markings are integral for introducing clinical sciences. Aim: This study aimed to assess which learning approach is effective in learning surface anatomy. Method: First-year medical students were randomly assigned into two groups and asked to complete an MCQs quiz covering surface anatomy of the abdomen (pre-test). Each student worked on his/her own in each group. Group A students (n=70) were then provided with a reading material and two images of the abdomen printed on A4 size paper. Students were asked to study the reading material and use the image of the abdomen to draw and label the surface anatomy of six abdominal organs. Group B students (n=74) were provided with the same reading material but were asked to answer short-answer questions. After 45minutes, the reading material and answers were collected from both groups and student's performance was compared using the same sets of MCQs (post-test). Results: Students from both groups showed significant improvement in their post-test scores compared to their pre-test scores. Also the means for paired samples were significantly higher in Group A compared to Group B. A small number of students in both groups scored≤2 in the pre-test and failed the post-test. Conclusion: While both techniques improved students' scores; learning by drawing surface anatomy of abdominal organs showed higher scores. © 2011 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted. Source


Simos T.E.,King Saud University | Simos T.E.,University of Peloponnese
Journal of Mathematical Chemistry | Year: 2014

In this paper we will develop an explicit fourth algebraic order four-step method with phase-lag and its first and second derivatives vanished. The comparative error and the stability analysis of the above mentioned paper is also presented. The new obtained method is applied on the resonance problem of the Schrödinger equationIn order in order to examine its efficiency. The theoretical and the computational results shown that the new obtained method is more efficient than other well known methods for the numerical solution of the Schrödinger equation and related initial-value or boundary-value problems with periodic and/or oscillating solutions. © 2013 Springer Science+Business Media New York. Source


Aly M.S.,King Saud University
Materials and Design | Year: 2010

Open-cell nickel foams with average pore size of 600 μm have been subjected to room temperature tensile tests to explore their tensile properties. Using a state of the art extensometer of non-contact type, foam properties as ultimate tensile strength (UTS), yield strength (YS) and the Young's modulus (E) have been measured accurately. An extensometer of non-contact type was applied for the first time to help the foam's mechanical properties to be determined accurately. The reason behind the usage of this kind of extensometer is to avoid completely any minor deformation that might be caused by the attachment of conventional extensometer to the sample's surface prior to testing. The function of this extensometer is based on the usage of a laser (CCD) camera that detects and records the dimensional changes as soon as the load is applied. The fracture behavior of foam cells was observed to be ductile. Complete separation of struts or cell walls took place successively by necking. © 2009 Elsevier Ltd. All rights reserved. Source


Hayat S.,King Saud University
Plant signaling & behavior | Year: 2012

When exposed to stressful conditions, plants accumulate an array of metabolites, particularly amino acids. Amino acids have traditionally been considered as precursors to and constituents of proteins, and play an important role in plant metabolism and development. A large body of data suggests a positive correlation between proline accumulation and plant stress. Proline, an amino acid, plays a highly beneficial role in plants exposed to various stress conditions. Besides acting as an excellent osmolyte, proline plays three major roles during stress, i.e., as a metal chelator, an antioxidative defense molecule and a signaling molecule. Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species (ROS) within normal ranges, thus preventing oxidative burst in plants. Reports indicate enhanced stress tolerance when proline is supplied exogenously at low concentrations. However, some reports indicate toxic effects of proline when supplied exogenously at higher concentrations. In this article, we review and discuss the effects of exogenous proline on plants exposed to various abiotic stresses. Numerous examples of successful application of exogenous proline to improve stress tolerance are presented. The roles played by exogenous proline under varying environments have been critically examined and reviewed. Source


Almogren A.,King Saud University
African Journal of Microbiology Research | Year: 2011

Host defense against Mycobacterium tuberculosis (MTB) is essentially a cell mediated immune response. The aim of this study is to assess immune abnormalities in the peripheral blood lymphocyte subsets in patients with pulmonary tuberculosis. Flowcytometry data for peripheral blood lymphocyte subsets in ten patients (mean age of 27 ± 6 years) with pulmonary tuberculosis were compared with similar data from 25 normal healthy individuals (mean age 24 ± 6 years) retrospectively in Immunology Unit at King Khalid University Hospital, Riyadh. The absolute numbers (523.7 ± 360.9 vs 177.1 ± 133.7, p = 0.0000) and % (28 ± 12.8% vs 9.9 ± 5.6%, p = 0.0000) of the natural killer cells and B lymphocytes (426.8 ± 452.1 vs 205.7 ± 69 p = 0.0000 and 18.2 ± 8.1% vs 11 ± 2.5%, p = 0.0000, respectively) were significantly higher in patients with PTB than the normal healthy individuals. A marked reduction in the absolute numbers (542.9 ± 350.3 vs 775.7 ± 225.4, p = 0.0250) and the percentage (30.8 ± 10.7% vs 44.01 ± 5.4%, p = 0.0000) of CD4 + cells in patients with pulmonary tuberculosis was also noted. Elevated natural killer and B cells with CD4 + lymphopenia in pulmonary tuberculosis prompt further investigations to gain a better understanding of host defense against M. tuberculosis. © 2011 Academic Journals. Source


Lam A.Y.S.,University of California at Berkeley | Li V.O.K.,University of Hong Kong | Li V.O.K.,King Saud University | Yu J.J.Q.,University of Hong Kong
IEEE Transactions on Evolutionary Computation | Year: 2012

Optimization problems can generally be classified as continuous and discrete, based on the nature of the solution space. A recently developed chemical-reaction-inspired metaheuristic, called chemical reaction optimization (CRO), has been shown to perform well in many optimization problems in the discrete domain. This paper is dedicated to proposing a real-coded version of CRO, namely, RCCRO, to solve continuous optimization problems. We compare the performance of RCCRO with a large number of optimization techniques on a large set of standard continuous benchmark functions. We find that RCCRO outperforms all the others on the average. We also propose an adaptive scheme for RCCRO which can improve the performance effectively. This shows that CRO is suitable for solving problems in the continuous domain. © 2012 IEEE. Source


Shah A.A.,King Saud University | Ribakov Y.,Ariel University
Materials and Design | Year: 2010

Nonlinear ultrasonic (NLU) and acoustic emission (AE) techniques are used for nondestructive evaluation of concrete, damaged under compression loading. Experiments were carried out in 18 cubic specimens (150 × 150 × 150mm) cast with three different w/c (six specimens for each w/c). Three specimens at each w/c were used for AE monitoring and three others for NLU evaluation. The NLU evaluation is based on measuring the change in fundamental amplitude with increasing damage and output power level. In acoustic emission testing technique four sensors were used to listen to the wide range of events under various loading and unloading cycles. An increase in AE hits was observed with increasing damage. Each loading and unloading stage was carefully examined for Kaiser and Felicity effects in order to assess the concrete deterioration. It was proposed to measure Felicity ratio at three different loading levels, corresponding to AE hits at 3%, 5%, and 10% of the AE hits at the previous maximum load, respectively. Normalized values of Felicity ratio were plotted and compared with the NLU test data. Correlation between acoustic emission and nonlinear ultrasonic techniques in assessing damage growth in concrete was investigated. © 2010 Elsevier Ltd. Source


In the present work, both experimental work and Finite Element Modeling (FEM) have been used to study the effects of notch geometry on the stress/strain behaviour and fracture of the ultra-high molecular weight polyethylene (UHMWPE) at quasi static conditions. The effects of notch profile radii on UHMWPE fracture behaviour, predicted stress/strain distribution, triaxial state of stress and hydrostatic pressure across the neck have been studied. Different techniques have been used to study the effects of notch geometry on the UHMWPE properties. Differential Scanning Calorimetry (DSC) has been used to study the changes in the tested material crystallinity. The universal testing machine has been used to measure the changes in the tested material mechanical properties. The SEM has been used to examine the change in the tested material fracture surface. Finally, the Finite Element Code (ANSYS10) has been used to investigate the effects of notch geometry on the predicted stress/strain distribution across the neck. The results show a notch strengthening behaviour for the tested material, where the axial yield properties increased significantly with the reduction of notch radii, while the axial ultimate properties decreased significantly for the notched specimens compared with plain ones. Also the predicted stress/strain distribution and stress triaxiality show a strong dependence on the notch geometry. The remarkable effects of notch geometry on the predicted stress/strains distributions across the neck show the importance of careful design of UHMWPE artificial joint components with the aim to eliminate the presence of stress risers such as undercuts and fillets. © 2009 Elsevier Ltd. All rights reserved. Source


Al-Muhsen S.,King Saud University
Saudi Journal of Gastroenterology | Year: 2010

Primary immune deficiency diseases (PIDs) are a heterogeneous group of inherited diseases characterized by variable genetic immune defects, conferring susceptibility to recurrent infections. They have a vast array of manifestations some of which involve the gastrointestinal and hepatobiliary systems. These complications can be the consequence of five different factors, namely, infection, autoimmune process, unregulated inflammation, malignancies and complications of therapeutic intervention. They may precede the PID diagnosis and, once developed, they pose high risk of morbidity. Untrained clinicians may treat these manifestations only at the level of their presentation, leaving the PIDs dangerously undiagnosed. In fact, early diagnosis of PIDs and accompanied gastrointestinal and hepatic complications clearly require appropriate treatment, and in-turn lead to an improved quality of life for the patient. To improve the awareness of gastroenterologists and related health care providers about these diseases, we have reviewed herein the complications of different PIDs focusing on gastrointestinal and hepatic manifestation. Source


For children between 5-10 years of age with zone II flexor tendon lacerations, the literature recommends a modified early mobilization programme under the supervision of a hand therapist but the fingers are immobilized between physiotherapy sessions. We report on a series of children between 5-10 years of age with flexor tendon lacerations (n = 54 fingers) in zone II repaired with a six-strand core suture (three separate 'figure of eight' sutures) and actively mobilized immediately after surgery similar to adult rehabilitation programmes with no immobilization between the physiotherapy sessions. The average follow-up for the study group was 13 months (range 7-25 months). There were no ruptures. The final outcome was excellent in 46 fingers (85%) and good in the remaining eight fingers (15%) using the Strickland-Glogovac criteria. © 2011 The Author(s). Source


Background: While it is known that advanced age alters the recruitment of neutrophils during wound healing, thereby delaying the wound healing process, little is known about prolonged wound healing in advanced ages. Thus, we investigated the correlation of neutrophil recruitment with healing events, and the impact of whey protein (WP) on neutrophil activation.Methods: The animals were allocated into wounded young group, wounded older group and wounded older rats with daily treatment of WP at a dose of 100 mg/kg of body weight.Results: Our results pointed to a marked deficiency in the number of neutrophils in the wounds of older rats, which was accompanied with impairment of the healing process. In the group of older rats, phagocytic activity, as tested by fluorescence microscopy, declined throughout the first 24 hours after wounding. Both the neutrophil number and the phagocytic activity recovered in older rats which received WP supplementation. Interestingly, WP was found to significantly up-regulate the MIP-1α and CINC-1 mRNA expression in old rats. On the other hand, the wound size in older rats was significantly higher than that in younger ones. Blood angiogenesis was also significantly delayed in the older group as opposed to the young rats. WP, however, was found to return these indices to normal levels in the older rats. Proliferation and epidermal migration of the keratinocytes and the collagen deposition were also returned to the normal rates.Conclusions: This data confirms the critical role of neutrophil recruitment in the early inflammatory phase of wound healing in older rats. In addition, WP protein was used to improve neutrophil function in older rats, healing events returned to a more normal profile. © 2014 Ebaid; licensee BioMed Central Ltd. Source


Modeling and simulation of circulating fast fluidized bed reactors (CFFBR) and circulating fast fluidized bed membrane reactors (CFFBMR) for hydrogen production by oxidative reforming of methane are presented in this paper. The results show that the CFFBR suffers from serious problems of hot spot temperatures. The combined effect of the oxygen distribution and the hydrogen membrane in the CFFBMR eliminates the hot spot temperatures and the danger of the reactor thermal runaway and mitigates nicely the temperature along the length of the CFFBMR. The investigation shows that the oxidative reforming of methane in the CFFBMR with oxygen distribution is cost-effective and inexpensive alternative route to the conventional steam reforming of methane processes due to the in situ heat integration of exothermic and endothermic reactions. The key role of the design parameters on the performance of the reactors are recognized through sensitivity analysis. The simulation results indicate that almost complete conversion of methane (99.99%), high exit hydrogen yield of 3.00 and low exit temperature of 569.8 °C are obtained by proper selection of design parameters of the CFFBMR with oxygen distribution. This achievement occurs at low feed temperature of 350.0 °C, which does not have destructive effects on the catalyst, reactor and membrane. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Alqahtani A.,King Saud University
Surgical Endoscopy and Other Interventional Techniques | Year: 2011

Background Minimally invasive techniques are becoming the gold standard approach to surgical treatment of obesity in adults. Robotic surgical systems have the potential to advance the use and development of minimally invasive procedures. To date, there is no study of outcomes following robotic-assisted gastric banding (RAGB) compared with laparoscopic adjustable gastric banding (LAGB) in children and adolescents. This study was undertaken to compare a single surgeon's results using the da Vinci surgical system for RAGB with those using LAGB in this group of patients. Methods A retrospective data analysis of 25 patients who underwent RAGB compared with 50 patients who underwent LAGB. Results The 75 patients were 8-21 years of age and included 42 (54.5%) girls. Patients in the two groups had similar baseline characteristics including gender, age, body mass index (BMI), and presence of comorbidities. No significant differences in complication rate, length of stay or percent excess weight loss at 1 year were found between the two groups. Mean operating time was significantly shorter for LAGB (50 min) compared with RAGB (74 min; P<0.001). Conclusions This comparative study between RAGB and LAGB in children and adolescents demonstrates the feasibility and safety of RAGB. However, the procedure requires significantly more operative time than LAGB and fails to provide improved patient outcome. © Springer Science+Business Media, LLC 2011. Source


Objective: Data on Hormone Receptor and Her-2/neu expression in breast cancers from Saudi Arabia and Gulf Region is sparse. We undertook this study to describe the patterns of hormone receptor and Her-2/neu protein expression in breast carcinoma and compared them with the histological grade at a University Hospital in Riyadh. Material and Method: We conducted a retrospective study on 164 invasive ductal carcinoma of breast between the year 2002 and 2008. Immunohistochemical analysis for Estrogen and Progesterone Receptor and Her-2/neu was done in all the cases. Fluorescent in situ hybridization for Her-2/neu gene amplification was performed in all 2+ cases and few equivocal 1+ and 3+cases by immunohistochemistry. Correlation between Estrogen and Progesterone Receptor and Her-2/ neu amplification and grade of tumor was calculated. Results: Te expression of Estrogen Receptor, Progesterone Receptor were significantly correlated (p<0.001). Also, there was a significant negative correlation between expression of hormone receptor and Her-2/neu amplification. Te histologic grade of the tumor was significantly correlated to the expression of both Estrogen and Progesterone Receptor. However, the relationship between Her-2/ neu amplification and grade was not significant and many of the grade III tumor were Her-2/neu negative. In addition, Her-2/neu gene amplification by fuorescent in situ hybridization was observed in 84.6% of breast cancer that were 3+ and in 18.75% cases that were 2+ by immunohistochemistry. Conclusion: Prevalence of Estrogen and Progesterone Receptor expression and Her-2/neu amplification in breast cancer in the Saudi Arabian population is similar to that reported internationally. Tere is a negative correlation between hormone receptors expression and Her-2/neu amplification. However not all of the high-grade breast cancers showed Her-2/neu positive status. Source


Kosti A.A.,University of Peloponnese | Simos T.E.,University of Peloponnese | Simos T.E.,King Saud University
Computer Physics Communications | Year: 2012

In this work a procedure for the construction of an explicit optimized Runge-Kutta-Nyström method with four stages and fifth algebraic order is provided. The variable coefficients of the preserved method result after nullifying the phase-lag, the dissipative error and the first derivative of the phase-lag. We can see the efficiency of the new method through its local truncation error. Furthermore, we compare the new methods efficiency to other numerical methods. This is shown through the integration of the two-body problem with various eccentricities and of four other initial value problems. © 2011 Elsevier B.V. Source


Noor M.A.,COMSATS Institute of Information Technology | Noor M.A.,King Saud University
Mathematical and Computer Modelling | Year: 2011

In this paper, we suggest and analyze some three-step iterative methods for solving general nonconvex variational inequalities using the technique of updating the solution. We show that the convergence of these iterative methods requires only the partially relaxed strongly monotonicity which is a weaker condition than cocoerciveness. We are also discuss several special cases. Our method of proof is very simple compared with other techniques. © 2011 Elsevier Ltd. Source


Islam S.K.H.,Birla Institute of Technology and Science | Khan M.K.,King Saud University
Journal of Medical Systems | Year: 2014

Recently, many authentication protocols have been presented using smartcard for the telecare medicine information system (TMIS). In 2014, Xu et al. put forward a two-factor mutual authentication with key agreement protocol using elliptic curve cryptography (ECC). However, the authors have proved that the protocol is not appropriate for practical use as it has many problems (1) it fails to achieve strong authentication in login and authentication phases; (2) it fails to update the password correctly in the password change phase; (3) it fails to provide the revocation of lost/stolen smartcard; and (4) it fails to protect the strong replay attack. We then devised an anonymous and provably secure two-factor authentication protocol based on ECC. Our protocol is analyzed with the random oracle model and demonstrated to be formally secured against the hardness assumption of computational Diffie-Hellman problem. The performance evaluation demonstrated that our protocol outperforms from the perspective of security, functionality and computation costs over other existing designs. © 2014, Springer Science+Business Media New York. Source


This paper reviews the molecular basis of the clinical features of Al-Awadi-Raas-Rothschild (limb/pelvis/uterus-hypoplasia-aplasia) (AARRS) syndrome and Fuhrmann syndrome. Human WNT7A mutations are also reviewed. Based on this review, these mutations will be classified into two main groups of phenotypes: Fuhrmann and AARRS phenotypes in which there is partial and complete loss of WNT7A functions, respectively. © 2013 Wiley Periodicals, Inc. Source


Alshatwi A.A.,King Saud University
Journal of Experimental and Clinical Cancer Research | Year: 2010

Catechin hydrate (CH), a strong antioxidant that scavenges radicals, is a phenolic compound that is extracted from plants and is present in natural food and drinks, such as green tea and red wine. CH possesses anticancer potential. The mechanism of action of many anticancer drugs is based on their ability to induce apoptosis. In this study, I sought to characterize the downstream apoptotic genes targeted by CH in MCF-7 human breast cancer cells. CH effectively kills MCF-7 cells through induction of apoptosis. Apoptosis was confirmed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and real-time PCR assays. Cells were exposed to 150 g/ml CH and 300 g/mL CH for 24 hours, which resulted in 40.7% and 41.16% apoptotic cells, respectively. Moreover, a 48-hour exposure to 150 g/ml CH and 300 g/ml CH resulted in 43.73% and 52.95% apoptotic cells, respectively. Interestingly, after 72 hours of exposure to both concentrations of CH, almost 100% of cells lost their integrity. These results were further confirmed by the increased expression of caspase-3,-8, and -9 and TP53 in a time-dependent and dose-dependent manner, as determined by real-time quantitative PCR. In summary, the induction of apoptosis by CH is affected by its ability to increase the expression of pro-apoptotic genes such as caspase-3, -8, and -9 and TP53. © 2010 Alshatwi; licensee BioMed Central Ltd. Source


Al-Qattan M.M.,King Saud University
Journal of Hand Surgery | Year: 2016

Purpose To report a case series of atypical lipomas of the hand and forearm and review the literature to define the clinical presentation, surgical approach, and postoperative complications including recurrence. Methods All cases of atypical lipomas of the hand and forearm treated by the author between 1994 and 2010 were retrospectively reviewed. The charts were reviewed for age, gender, tumor site, symptoms, preoperative studies, tumor size, type of surgical excision, and postoperative complications including recurrence. Results Nine cases were identified. All patients were middle-aged adults with a mean age of 55 years (range, 40-65 years). There were 5 women and 4 men. All patients presented with a single, painless, enlarging mass in either the palm or the volar forearm. Magnetic resonance imaging showed the tumors to be hyperintense on T1- and hypointense on T2-weighted images. All patients had marginal excision of the tumor. Histologically, 5 tumors were conventional, and 4 tumors were cellular atypical lipomas. The mean follow-up was 10 years (range, 6-16 years). There was no evidence of recurrence by clinical examination at final follow-up. Conclusions The results of the current series and a review of the literature suggest that atypical lipomas of the hand and forearm may have a more benign behavior than atypical lipomas of other anatomical sites. Copyright © 2016 by the American Society for Surgery of the Hand. All rights reserved. Source


Saba T.,Prince Sultan University | Altameem A.,King Saud University
Applied Artificial Intelligence | Year: 2013

The purpose of this article is to analyze current vision-based systems from a soccer video semantic point of view such as video summarization, features analysis, and provision of augmented information. Currently, computer vision techniques are applicable in a challenging soccer context. Scene interpretation is performed based on the complexity of the semantic. For each area of vision-based systems, computer vision methodologies are analyzed along with their strengths and weaknesses. We have also investigated whether the existing approaches are equally applicable for real-time soccer video semantic analysis. © 2013 Taylor & Francis Group, LLC. Source


Khalil M.S.,Suez Canal University | Khalil M.S.,King Saud University
Histology and Histopathology | Year: 2015

There are many available drugs for treating gastric ulcer, but they have various side effects. Ginger is a folk, herbal medicine, which is used for treatment of various diseases including gastric ulcer. This study investigates the possible mechanism of the protective effect of ginger on aspirin induced gastric ulcer. Forty adult male albino rats were randomized into four groups (10 animals per each group) and orally received the followings once daily for 5 days: Group I: 3 ml of 1% carboxymethyl cellulose; Group II: ginger powder (200 mg/kg body weight) suspended in 3 mL of 1% carboxymethylcellulose; Group III: aspirin (400 mg/kg body weight) suspended in 3 ml of 1% carboxymethylcellulose in water. Group IV: ginger and 30 minutes later, received aspirin suspended in 1% carboxymethylcellulose, in similar doses as received in groups II and III. On day 6, rats were sacrificed. The animals were anesthetized and the stomach was removed for the macroscopic, histological (Haematoxylin and Eosin and Periodic Acid Shiff) and immunohistochemical investigations (Bax, inducible nitric oxide synthase and heat shock protein 70). Aspirin induced a significant increase of the macroscopic ulcer score, shed and disrupted epithelium, mucosal hemorrhage, submucosal edema and leukocyte infiltration, loss of the mucus of the mucosal surface significantly increased expression of apoptosis regulator Bax, inducible nitric oxide synthase (iNOS) and heat shock protein 70 (HSP70). Ginger ameliorated the histological changes by reducing Bax and iNOS and increasing HSP70 expressions. © 2015 Histology and Histopathology. All rights reserved. Source


Kurdi H.A.,King Saud University
Journal of King Saud University - Computer and Information Sciences | Year: 2015

The visible success of the Peer to Peer (P2P) paradigm is associated with many challenges in finding trustworthy peers as reliable communication partners. Reputation management systems are emerging in the face of these challenges. The EigenTrust reputation management system is among the most known and successful reputation systems. On the other hand, a main drawback of this system is its reliance on a set of pre-trusted peers which causes nodes to center around them. As a consequence, other peers are ranked low despite being honest, marginalizing their effect in the system. To tackle this problem, this paper proposed enhancing the EigenTrust algorithm by giving peers with high reputation values (honest peers) a role in calculating the global reputation of other peers. Rather than solely depending on the static group of pre-trusted peers, the proposed algorithm, HonestPeer, selects the most reputable nodes, honest peers, dynamically based on the quality of the provided files. This makes HonestPeer more robust to the increase in the number of files and nodes in the system. Through simulation, it has been shown that HonestPeer has successfully maintained higher success rate and lower percentage of inauthentic downloads when compared to the original algorithm. © 2015 The Author. Source


Tarawneh Q.,King Saud University
Theoretical and Applied Climatology | Year: 2015

Annual rainfall records of 20 stations for 30 years are used in order to detect rainfall regimes and climatic features of Saudi Arabia using harmonic analysis techniques. In this study, the percentages of variance, amplitudes, and phase angles are calculated in order to depict the spatial and temporal characteristics of the country’s rainfall. The first harmonic explains 42 % of rainfall variation in the western (W) region. This percentage increases toward east (E) and north (N) with 69 and 67 %, respectively. In the southwest (SW) region, the percentages explain 43 % of rainfall variation. The percentages of variance in W and SW are lower than in the E, NW, and central (C) regions. This implies significant contributions of the second harmonic in W and SW regions with 26 and 16 %, respectively. The high percentages of the second and third harmonics in W and SW regions suggest that these two regions are affected by different weather systems at different times. The SW region has the highest amplitudes of the first, second, and third harmonics. The amplitude of the first harmonic reaches to 21 mm in SW and 9 mm in both C and E regions. The time of maximum rainfall is calculated using phase angle; the result reflects that maximum rainfall is shifted forward on the time axis toward the spring season in SW and C regions, January in E and NW regions, and October and November in the W region. This reveals that the SW region is a completely different climatic region, though some of what affects this region also affects the central region. Conditions in the E and NW regions are mainly affected by Mediterranean weather systems, while the W region is affected by unstable conditions caused by the active Red Sea Trough (RST) in October and November. © 2015 Springer-Verlag Wien Source


Direct observation of procedural skills (DOPS) is a new workplace assessment tool. The aim of this narrative review ofliterature is to summarize the available evidence about the validity, reliability, feasibility, acceptability and educationalimpact of DOPS. A PubMed database and Google search of the literature on DOPS published from January 2000 toJanuary 2012 was conducted which yielded 30 articles. Thirteen articles were selected for full text reading and review. Inthe reviewed literature, DOPS was found to be a useful tool for assessment of procedural skills, but further research isrequired to prove its utility as a workplace based assessment instrument. Source


In the present study, the two endemic Soqotraen plants Boswellia elongata and Jatropha unicostata were investigated for their anti-inflammatory, antinociceptive and antioxidant potential. To assess the anti-inflammatory and antinociceptive activities, two concentrations of each extract (200 and 400. mg/kg, p.o.) were tested in carrageenan-induced rat paw edema, cotton pellet granuloma in rats, acetic acid-induced abdominal writhing and hot-plate test model in mice. Moreover, the antioxidant activity was determined in vitro, using scavenging activity of DPPH radical and β-carotene-linoleic acid assays. Both plants produced significant (P< 0.05-0.01) anti-inflammatory and antinociceptive effects; however the results suggest that B. elongata possesses the highest activities. B. elongata and J. unicostata at (400. mg/kg) reduced the paw edema considerably (82% and 53%) and the weight of cotton pellet granuloma (51% and 32%), respectively. Furthermore, they diminished the abdominal constriction induced by acetic acid with a 67% and 41% inhibition respectively, and prolonged significantly the reaction time of animal with relatively extended duration of stimulation. In addition, both plants showed considerable antioxidant activity in both assays. These results clearly confirmed the traditional anti-inflammatory indication of B. elongata and suggest that B. elongata could be a potential source for anti-inflammatory, antinociceptive and antioxidant agents. © 2011 Elsevier Ltd. Source


Alsuwaida A.O.,King Saud University
Modern Rheumatology | Year: 2014

Objectives. Repeated kidney biopsies are increasingly recognized to be pivotal in the management of various phases of lupus nephritis. The aim of this retrospective study was to examine the shift in activity index and chronicity index among International Society of Nephrology/Renal Pathology Society (ISN/RPS) class patients with lupus nephritis who undergo a triple kidney biopsy. Methods. Eleven patients with lupus nephritis and 3 biopsies each were assessed and reclassified based on ISN/RPS classification. Results. The mean creatinine level increased from 74 (± 38) μmol/l at baseline to 129 (± 116) μmol/l at the second biopsy and to 204 (± 200) μmol/l at the last biopsy. Among 11 kidney biopsies, 7 (63.7%) had a different ISN/RPS class in the second biopsy. The third biopsy showed that six kidney biopsies had a different ISN/RPS class compared to the second biopsy. Even among patients who stayed in the same ISN/RPS class, the second and third biopsies gave a different activity and/or chronicity index. The median activity index (range) was 3.1 (0-14), 4 (0-13) and 3 (0-14) for the first, second and third biopsies, respectively. The median chronicity indices (range) were 2.5 (0-8), 7 (0-8) and 5 (0-10), respectively. Conclusion. My study has shown that lupus nephritis is a shifting disease, and repeated biopsies are a pivotal policy in its management. © 2014 Japan College of Rheumatology. Source


Abiraterone (ABR) is a rationally designed CYP17 inhibitor that blocks the conversion of androgens from non-gonadal precursors effectively, thus reducing testosterone to undetectable levels. With the objective of reducing analysis time and maintaining good efficiency, there has been substantial focus on high-speed chromatographic separations, and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) is a pre-eminent analytical tool for rapid biomedical analysis. In this study a rapid and precise UPLC-MS/MS method has been developed and validated for the determination of ABR in plasma. After a simple protein precipitation using methanol, ABR and carbamazepine (internal standard; IS) were separated on an Acquity UPLC BEH™ C18 column (50 × 2.1 mm, i.d. 1.7 μm, Waters, USA) using a mobile phase of acetonitrile:water:formic acid (90:10:0.1%, v/v/v) pumped at a flow rate of 0.3 mL min-1. ABR and IS were eluted at 0.61 and 0.48 min, respectively. The mass spectrometric determination was carried out using an electrospray interface operated in the positive mode with multiple reaction monitoring (MRM) mode. The precursors to product ion transitions of m/z 350.1 > 156.0, and m/z 237.0 > 179.0 were used to quantify ABR and IS, respectively and m/z 350.1 > 170.0 transition was used as the qualifying ion for ABR. The method was linear in the concentration range of 0.1-50 ng mL -1 with good correlation coefficient of (0.995) and with a limit of quantitation of 0.1 ng mL-1. The intra- and inter-assay precisions were satisfactory; the relative standard deviations did not exceed 13.29%. The accuracy of the method was proved; recoveries of ABR from spiked human plasma were 75.83-78.33%. The proposed UPLC-MS/MS method is simple, rapid and highly sensitive, and hence it could be reliable for pharmacokinetic and toxicokinetic studies in both animals and humans. © 2013 The Royal Society of Chemistry. Source


Al-Yousefi N.A.,King Saud University
Journal of Religion and Health | Year: 2012

Although most patients report wanting their physicians to address the religious aspects of their lives, most physicians do not initiate questions concerning religion with their patients. Although religion plays a major role in every aspect of the life of a Muslim, most of the data on the role of religion in health have been conducted in populations that are predominantly non-Muslim. The objectives of this study were to assess Muslim physicians' beliefs and behaviours regarding religious discussions in clinical practice and to understand the factors that facilitate or impede discussion of religion in clinical settings. The study is based on a cross-sectional survey. Muslim physicians working in a tertiary care hospital in Saudi Arabia were invited to complete a questionnaire that included demographic data; intrinsic level of religiosity; beliefs about the impact of religion on health; and observations, attitudes, behaviours, and barriers to attending to patients' religious needs. Out of 225 physicians, 91% agreed that religion had a positive influence on health, but 62. 2% thought that religion could lead to the refusal of medically indicated therapy. Over half of the physicians queried never asked about religious issues. Family physicians were more likely to initiate religious discussions, and physicians with high intrinsic religiosity were more likely to share their own religious views. Residents and staff physicians tended to avoid such discussions. The study results highlight the fact that many physicians do not address patients' religious issues and that there is a need to clarify ethically sound means by which to address such needs in Islamic countries. Medical institutions should work to improve the capacity of medical personnel to appropriately address religious issues. The training of clinical religious advisors is a promising solution to this dilemma. © 2012 Springer Science+Business Media, LLC. Source


Abouammoh M.A.,King Saud University
Canadian Journal of Ophthalmology | Year: 2013

Objective: To conduct a systematic review on the safety of ranibizumab injections for diabetic macular edema by meta-analysis of recently conducted level 1 randomized clinical trials. Design: A meta-analysis and systematic review. Methods: Main outcome measures of permissible studies were extracted and reported. The relative risk (RR) for thromboembolic events (TEEs) was calculated for those studies that met this study's inclusion criteria. The fixed-effects model (Mantel-Haenszel method) was appropriately used to calculate the pooled RR. The quality of trials was assessed using the Jadad score. Results: Of the 2072 patients who were included from 5 eligible randomized clinical trials, 1295 patients received intravitreal ranibizumab injections. The pooled RR for TEEs after ranibizumab intravitreal injection was 0.74 (95% CI 0.52-1.06). Conclusions: Intravitreal ranibizumab for the treatment of diabetic macular edema did not increase the risk for TEEs as shown by this meta-analysis of 5 randomized, controlled clinical trials. © 2013 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved. Source


Marie M.A.M.,King Saud University
Journal of Korean Medical Science | Year: 2012

Helicobacter pylori has been strongly associated with gastritis, gastric and duodenal ulcers, and it is a risk factor for gastric cancer. Two major virulence factors of H. pylori have been described: the cytotoxin-associated gene product (cagA) and the vacuolating toxin (vacA). Since considerable geographic diversity in the prevalence of H. pylori virulence factors has been reported, the aim of this work was to determine if there is a significant correlation between different H. pylori virulence genes (cagA and vacA) in 68 patients, from Saudi Arabia, and gastric clinical outcomes. H. pylor was recognized in cultures of gastric biopsies. vacA and cagA genes were detected by polymerase chain reaction (PCR). The cagA gene was obtained with 42 isolates (61.8%). The vacA s- and m- region genotypes were determined in all strains studied. Three genotypes were found: s1/m1 (28%), s1/m2 (40%) and s2/m2 (26%). The s2/m1 genotype was not found in this study. The relation of the presence of cagA and the development of cases to gastritis and ulcer was statistically significant (P < 0.05). The study showed a significant correlation between the vacA s1/m2 genotype and gastritis cases, and a significant correlation between vacA s1/m1 genotype and peptic ulcer cases. The results of this study might be used for the identification of high-risk patients who are infected by vacA s1/m1 genotype of H. pylori strains. In conclusion, H. pylori strains of vacA type s1 and the combination of s1/m1 were associated with peptic ulceration and the presence of cagA gene. © 2012 The Korean Academy of Medical Sciences. Source


Sundarrajan S.,National University of Singapore | Allakhverdiev S.I.,RAS Institute of Basic Biological Problems | Ramakrishna S.,National University of Singapore | Ramakrishna S.,King Saud University
International Journal of Hydrogen Energy | Year: 2012

Micro Direct Methanol Fuel cells (μDMFC) are of considerable interest for both academic laboratories and industries to commercialize, since the energy demand has been increased. Although intensive researches are conducted to understand μDMFC, many challenges still remain to be solved to exploit them for real commercial applications. The pros and cons of various substrate materials used and various designs fabricated so far for fuel delivery are highlighted. One of the existing problems is membrane swelling, which has been reduced by the polymer modification recently. The removal of evolved CO 2 gas in the anode and reduction of water flooding in the cathode are accomplished through the advanced materials fabrication is discussed. The important parameters such as fuel, water, air and thermal managements to increase cell performance by material manipulation and design are outlined in this review. A handful of companies are trying μDMFC technology toward real commercial strides. We have also presented an update of the achievements so far by these companies. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Azer S.A.,King Saud University
Academic Medicine | Year: 2015

Purpose To identify and examine the characteristics of the 50 top-cited articles in medical education. Method Two searches were conducted in the Web of Knowledge database in March 2014: a search of medical education journals in the category "Education, Scientific Discipline" (List A) and a keyword search across all journals (List B). Articles identified were reviewed for citation count, country of origin, article type, journal, authors, and publication year. Results Both lists included 56 articles, not 50, because articles with the same absolute number of citations shared the same rank. The majority of List A articles were published in Academic Medicine (34; 60.7%) and Medical Education (16; 28.6%). In List B, 27 articles (48.2%) were published in medical education journals, 19 (33.9%) in general medicine and surgery journals, and 10 (17.9%) in higher education and educational psychology journals. Twenty-six articles were included in both lists, with different rankings. Reviews and articles constituted the majority of articles; there were only 8 research papers in List A and 13 in List B. Articles mainly originated from the United States, Canada, the Netherlands, and the United Kingdom. The majority were published from 1979 to 2007. There was no correlation between year and citation count. Conclusions The finding that over half of List B articles were published in nonmedical education journals is consistent with medical education's integrated nature and subspecialty breadth. Twenty of these articles were among their respective non-medical-education journals' 50 top-cited papers, showing that medical education articles can compete with subject-based articles. Copyright © by the Association of American Medical Colleges. Unauthorized reproduction of this article is prohibited. Source


Alhammad N.S.,King Saud University
Odonto-stomatologie tropicale = Tropical dental journal | Year: 2010

The purpose of this study was to determine the caries experience and oral hygiene (OH) status of cerebral palsy (CP) children in Riyadh area. One hundred and forty CP children [82 (58.6%) males & 58 (41.4%) females] were examined for dental caries and OH status in dental clinic of the Disabled Children's Association Center, Riyadh. The children were divided into three age groups; first group 3-6 years old (41 children), second group 7-9 years old (52 children) and third group 10-12 years old (47 children). The mean DMFS (decayed, missing and filled surfaces) score for the first group was 18.8 (+/- 16.3), with the DS component of 10.9 (+/- 7.5), MS component of 3.7 (+/- 10.4) and FS component of 4.1 (+/- 8.9). For the second group the mean DMFS was 23.4 (+/- 17.7) with DS component of 15.4 (+/-12.1), MS component of 4.1 (+/-9.0) and FS component of 3.8 (+/- 8.5). The corresponding values for the third group were 20.5 (+/- 14.0), 12.4 (+/- 9.7), 5.1 (+/- 12.4) and 2.9 (+/- 5.5) respectively. There was no statistically significant difference (p > 0.05) in caries experience between the three age groups. Very few (5.7%) CP children were rated as having good OH. There was a strong association between poor oral hygiene status and high DMFS score. It can be concluded that the caries experience of CP children in Riyadh is very high, and that very few of these children have good oral hygiene. Source


Fazal-E-Amin,King Saud University
Computers in Human Behavior | Year: 2015

The increased use of smartphones has established a trend of web browsing through smartphone browsers. On one hand many of the smartphone web browsers are available and on the other hand many of the websites are customized for mobile browsing. This paper presents the results of a study conducted to reveal the usage patterns of smartphones web browsers. Mix methods of research are used in this study. It is initiated with a qualitative part to lay down the basis for further investigations and concluded with a quantitative part. The results revealed about some of the insights on smartphone web browser usage patterns, which are equally helpful for the industry and academia. The findings are presented in following categories: number of usage sessions per day, duration of sessions, common tasks performed, and frequently used browser features. Furthermore, usage patterns associated to these categories are identified and analyzed in context of age and experience groups. The findings suggest that respondents from 35 to 44years of age tend to use smartphone web browsers for less number of times in a day but have longer sessions. However, there is no significant difference in use of browser feature among different age groups. © 2014 Elsevier Ltd. All rights reserved. Source


Bouras A.,King Saud University
Computers in Human Behavior | Year: 2015

This paper presents an innovative approach to detect the main reasons causing the delay in communication between healthcare actors in a local hospital, with a special focus on communication between surgeons and physicians. The research methodology consists of using quality tools based on Six sigma principles, as fishbone diagram to identify factors affecting the communication in the surgery department, and the XY matrix to highlight the most affecting factors on patient health in terms of delay in communication. In that purpose, many dysfunctions in information exchange were noticed between surgeons, physicians, nurses, etc. As a conclusion, the study recommends the use of secured smartphones applications to access patients' records and the design of an architecture helping in reducing the current communication time for a faster service. This application aims also at securing communication between the major actors involved in the process of providing care. The use of computer applications will provide safe and efficient treatment for post-surgical patient and prevent/limit the complications after surgeries. © 2014 Elsevier Ltd. All rights reserved. Source


The title compounds were prepared by reaction of 6-acetyltetralin (1) with different aromatic aldehydes 2a-c, namely 2,6-dichlorobenzaldehyde, 2,6-diflourobenzaldehyde, and 3-ethoxy-4-hydroxybenzaldehyde, to yield the corresponding α,β-unsaturated ketones 3a-c. Compound 3b was reacted with hydrazine hydrate to yield the corresponding 2-pyrazoline 4, while compounds 3a,b reacted with thiourea to afford the 2-thioxopyrimidine derivatives 5a,b, respectively. The reaction of 1, and the aromatic aldehydes 2a-c with ethyl cyanoacetate, 2-cyano-thioacetamide or malononitrile in the presence of ammonium acetate yielded the corresponding 2-oxopyridines 6a,b, 2-thioxopyridines 7a-c or 2-iminopyridines 8a,b, respectively. The newly prepared compounds were evaluated for anticancer activity against two human tumor cell lines. Compound 3a showed the highest potency with IC50 = 3.5 and 4.5 μg/mL against a cervix carcinoma cell line (Hela) and breast carcinoma cell line (MCF7), respectively. © 2011 by the authors. Source


Batoo K.M.,King Saud University | El-Sadek M.-S.A.,South Valley University
Journal of Alloys and Compounds | Year: 2013

Nanoscale Ni0.7-xMgxCu 0.3Fe2O4 (0.0 ≤ x ≤ 0.5) ferrite powders were prepared by sol-gel method and obtained as dried gel after successful reaction between respective metal nitrates. X-ray diffraction (XRD) confirmed the successful synthesis of materials, and the formation of single-phase cubic spinel structure. The average particle sizes of these materials were found between 40 to 50 nm and confirmed by TEM (±1). Dielectric constant (*′) measured in the frequency range (42 Hz to 5 MHz) was found to decrease with increasing frequency of the applied field, which shows normal behavior, and has been explained in the light of Maxwell-Wagner interfacial polarization. Debye relaxation peaks were observed for lower concentration of Mg in frequency dependent dielectric loss tangent curves. Real and imaginary parts of impedance (Z′ and Z″) suggest existence of one relaxation mechanism which is attributed to the co-effect of grains and grain boundaries. The room temperature dc magnetization studies infer magnetic moment of Ni-Cu-Mg nanoparticles decreases with increasing Mg2+ doping content. © 2013 Elsevier B.V. All rights reserved. Source


Deraz N.M.,King Saud University
International Journal of Electrochemical Science | Year: 2013

X-ray diffraction (XRD) of nickel aluminate showed its structural properties such as crystallite size, lattice constant, unit cell volume and X-ray density. The nano-sized nickel aluminat (NiAl2O4) crystals were prepared in this study. The morphological properties and the surface concentration of elements involved in the spinel NiAl2O4 solid were studied by Scanning electron micrographs (SEM) and Energy dispersive X-ray (EDX) techniques. The results showed formation of single phase of nano-crystalline nickel aluminate with spinel structure. The nature of the as synthesized powders was spongy and fragile. © 2013 by ESG. Source


Deraz N.M.,King Saud University
International Journal of Electrochemical Science | Year: 2013

Various structural properties of cobalt aluminates such as crystallite size, lattice constant, unit cell volume, X-ray density, cation distribution of were determined by X-ray diffraction (XRD) and infrared (IR) techniques. Cobalt aluminates were prepared in this study by combustion route. The morphological properties of cobalt aluminates and the surface concentration of elements of these aluminates were studied by Scanning electron micrographs (SEM) and Energy dispersive X-ray (EDX) techniques. The results revealed that the method investigated led to formation of single phase of well crystalline cobalt aluminates (CoAl2O4) with spinel structure. The as synthesized powders were spongy and fragile. The change in amount of fuel used in the combustion method affects formation and crysatllinity of cobalt aluminates. © 2013 by ESG. Source


Soylak M.,Erciyes University | Soylak M.,King Saud University | Yilmaz E.,Erciyes University
Desalination | Year: 2011

A novel separation-preconcentration procedure based on ionic liquid dispersive liquid-liquid microextraction of traces lead as pyrrolidinedithiocarbamate chelate has been developed. 1-Hexyl-3-methylimidazolium hexafluorophosphate as ionic liquid was used for extraction of lead pyrrolidinedithiocarbamate chelate. After phase separation, the enriched analyte in the final solution is determined by flame atomic absorption spectrometry (FAAS). The effects of pH, amounts of ligand, amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate, sample volume etc. on the recoveries of lead ions were investigated. The influences of some cations and anions on the recoveries of lead were also examined. The preconcentration factor was calculated as 40 at the sample volume of 20. ml. The detection limit for lead ions was 1.5 μg/l. The validation of the presented method was performed by the analysis of TMDA-51.3 fortified water. The method was applied to natural water samples. © 2011 Elsevier B.V. Source


The present study describes a simple stability-indicating reversed-phase HPLC assay for antiplatelet drug, clopidogrel bisulfate. Separation of the drug and the degradation products, under stress conditions was successfully achieved on a C-18 column utilizing 0.01M Na 2HPO 4 (pH 4): acetonitrile in the ratio 80:20 v/v, pumped at a flow rate of 0.5mlmin -1 with UV detection at 235nm. The retention time of clopidogrel was 6.84min. The method was satisfactorily validated with respect to linearity, precision, accuracy, selectivity, sensitivity and ruggedness. The response was linear in the range of 0.2-3.5μgml -1 with detection limit 0.079μgml -1. The suggested method was successfully applied for the analysis of clopidogrel in bulk and in commercial tablets. The results were favorably compared to those obtained by a reference method. The proposed method was successfully applied to the content uniformity testing of tablets and for determination of clopidogrel in presence of its co-administered drug, acetyl salicylic acid. © 2010. Source


Simos T.E.,King Saud University | Simos T.E.,University of Peloponnese
Journal of Mathematical Chemistry | Year: 2012

In this paper we study the connection between: (i) closed Newton-Cotes formulae of high order, (ii) trigonometrically-fitted and exponentially-fitted differential methods, (iii) symplectic integrators. Several one step symplectic integrators have been produced based on symplectic geometry during the last decades (see the relevant literature and the references here). However, the study of multistep symplectic integrators is very poor. In this paper we investigate the High Order Closed Newton-Cotes Formulae and we write them as symplectic multilayer structures. We develop trigonometrically-fitted and exponentially-fitted symplectic methods which are based on the closed Newton-Cotes formulae. We apply the symplectic schemes in order to solve the resonance problem of the radial Schrödinger equation. Based on the theoretical and numerical results, conclusions on the efficiency of the new obtained methods are given. © 2011 Springer Science+Business Media, LLC. Source


Alghamdi K.M.,King Saud University
Journal of the European Academy of Dermatology and Venereology | Year: 2010

Background Although the practice of bleaching is common worldwide, there are few studies that discuss knowledge, attitudes and practices towards bleaching. Objective The aim of this study was to explore the knowledge, attitudes and practices towards the usage of topical bleaching agents among women. Methods A self-administered questionnaire on the use of bleaching creams was distributed randomly to women attending the outpatient clinics at a university hospital in Saudi Arabia during 2008. Results Five hundred and nine of 620 women responded (82% response rate). All the participants had dark skin (skin type 4-5). The mean age was 29.22 ± 9 years. Of the participants, 38.9% (197/506) were current users of bleaching agents. Only 26.7% (106/397) of the respondents used bleaching agents for medical purposes to treat localized abnormal skin hyper-pigmentation; 20.8% (101/485) were ready to use any bleaching cream that gives fast results, even if the components were unknown. Of the respondents, 30% (152/509) used more than 100 g of bleaching creams monthly. These products were applied to the whole body in 7.3% of the cases. While 10.3% (28/271) continued applying the bleaching products during pregnancy, 20.8% (54/260) did so during lactation. No associations could be found between the various sociodemographic variables and differences in the attitude towards and practice of using bleaching creams. Conclusion A major proportion of our sample respondents have overused and/or misused bleaching agents. This was regardless of age, income, education or marital status. There is a need to educate women about the possible risks. © 2010 European Academy of Dermatology and Venereology. Source


Sherif E.-S.M.,King Saud University | Sherif E.-S.M.,National Research Center of Egypt
Industrial and Engineering Chemistry Research | Year: 2013

A comparative study on the inhibition of iron corrosion in 3.5 wt % NaCl solutions by 5-phenyl-1H-tetrazole (PHTA) and 3-amino-1,2,4-triazole (ATA) was investigated using a variety of electrochemical measurements. The potential-time curves revealed that PHTA and ATA shift the potential of iron toward the positive values. Electrochemical impedance spectroscopy measurements indicated that the presence of PHTA and ATA and the increase of their concentrations decrease the iron corrosion by increasing the solution and polarization resistances. This effect also decreases the corrosion current and corrosion rate for iron as confirmed by potentiodynamic polarization data. Potentiostatic current-time curves indicated that the presence of PHTA and ATA molecules decreases the absolute current and severity of pitting corrosion of iron in the test solutions. In situ Raman spectra for iron in chloride solution containing PHTA and ATA confirmed that the inhibition of iron corrosion is achieved by the adsorption of PHTA and ATA molecules onto its surface. © 2013 American Chemical Society. Source


Alamri H.,Curtin University Australia | Low I.M.,Curtin University Australia | Alothman Z.,King Saud University
Composites Part B: Engineering | Year: 2012

Epoxy nanocomposites reinforced with recycled cellulose fibres (RCFs) and organoclay platelets (30B) have been fabricated and investigated in terms of WAXS, TEM, mechanical properties and TGA. Results indicated that mechanical properties generally increased as a result of the addition of nanoclay into the epoxy matrix. The presence of RCF significantly enhanced flexural strength, fracture toughness, impact strength and impact toughness of the composites. However, the inclusion of 1 wt.% clay into RCF/epoxy composites considerably increased the impact strength and toughness. The presence of either nanoclay or RCF accelerated the thermal degradation of neat epoxy, but at high temperature, thermal stability was enhanced with increased char residue over neat resin. The failure micromechanisms and energy dissipative processes in these nanocomposites were discussed in terms of microstructural observations. © 2012 Published by Elsevier Ltd. All rights reserved. Source


The aim of this study is to investigate the application of the ohmic heating during the evaporation process of the seawater for the purpose of reaching near zero liquid discharge (ZLD). Ohmic evaporator was designed and used to evaporate seawater at electrical field strengths 24, 56 and 87 V/cm using alternating electric current at frequency of 60 Hz. The apparent electrical conductivity, recovery rate and energy consumption were determined during the evaporation process. Some physico-chemical properties of the concentrated brine (sludge) were measured such as electrical conductivity, pH, density and color. Results indicate that the apparent electrical conductivity was reduced by increasing the electrical field strength. The ranges of the recovery rate and specific energy were 81-93.5% and 4550-5071 kJ/kg respectively. It was demonstrated that the ohmic evaporator performed better at electrical field strength 56 V/cm. One major output of this research is the assessment of the generation of heat in the seawater by alternating current during evaporation process for near-ZLD; although, more studies are needed for continuous pilot production system, modelling for commercial production as well as economical evaluation of the system. © 2011 Elsevier B.V. Source


Objectives: To investigate the potential role of antitumor necrosis factor-alpha (TNF-α) antibodies on some renal functions and release of vasoregulatory peptides using nitric oxide synthase deprived pregnant rats. Materials: This study was carried out at King Khalid University Hospital, King Saud University, Riyadh, Kingdom of Saudi Arabia from December 2011 to November 2012. Forty female Wistar rats were divided into 4 groups (10 rats each); Group I - included virgin non-pregnant rats. Group II - included pregnant rats that received saline, Group III - received NG-nitro-Larginine methyl ester (L-NAME), and Group IV - received both L-NAME and anti TNF-α antibodies. Mean arterial blood pressure, urine volume, creatinine clearance and 24 hours urinary albumin excretion were measured on day 20 of gestation. Blood samples were taken on day 20 of gestation for measurement of plasma endothelin-1 (ET-1), angiotensin II (Ag II) and serum levels of total nitric oxide (NO) products, interleukin-6 (IL-6) and soluble vascular cell adhesion molecule (sVCAM-1). Viable pups were also weighed. Results: Anti TNF-α antibodies reversed hypertension, improved renal function, decreased release of vasoactive substances and increased pup weight. Conclusion: Preeclampsia is associated with disturbed renal function, overproduction of cytokines and vasoregulatory factors, and fetal growth restriction. Treatment of pregnant rats with anti TNF-α antibodies, restored urine volume, creatinine clearance, plasma ET-1, serum IL-6 and sVCAM-1 to normal levels. Hence, anti TNF-α antibodies may have beneficial effects in preeclampsia. Additional studies are warranted to confirm these results. Source


El-Sayed A.K.,King Saud University | Soudki K.,University of Waterloo
Journal of Composites for Construction | Year: 2011

Several codes and design guidelines addressing fiber-reinforced polymer (FRP) bars as primary reinforcement for structural concrete have been recently published worldwide. This reflects the great progress in FRP research area that has been conducted by the research community over the past two decades. Most of these design provisions follow the traditional approach of Vc + Vs for shear design. Nevertheless, both equations of concrete contribution Vc and FRP stirrup contribution Vs to shear strength in these guidelines are different in the manner that they are calculated. In this paper, five methods for FRP shear design, currently used in design practice, were reviewed. These methods include the American Concrete Institute design guide, ACI 440.1R-06; the Canadian Standards Association, CAN/CSA-S806-02; the ISIS Canada design manual, ISIS-M03-07; the British Institution of Structural Engineers guidelines; and the design recommendations of the Japan Society of Civil Engineers. The five methods for shear design prescribed in these guidelines were compared with experimental database obtained from the literature. In addition, the modified compression field theory approach was reviewed and compared with the experimental database. © 2011 ASCE. Source


Azer S.A.,King Saud University
Anatomical Sciences Education | Year: 2013

The aims of this review were to examine the place of surface anatomy in the medical literature, particularly the methods and approaches used in teaching surface and living anatomy and assess commonly used anatomy textbooks in regard to their surface anatomy contents. PubMed and MEDLINE databases were searched using the following keywords "surface anatomy," "living anatomy," "teaching surface anatomy," "bony landmarks," "peer examination" and "dermatomes". The percentage of pages covering surface anatomy in each textbook was calculated as well as the number of images covering surface anatomy. Clarity, quality and adequacy of surface anatomy contents was also examined. The search identified 22 research papers addressing methods used in teaching surface anatomy, 31 papers that can help in the improvement of surface anatomy curriculum, and 12 anatomy textbooks. These teaching methods included: body painting, peer volunteer surface anatomy, use of a living anatomy model, real time ultrasound, virtual (visible) human dissector (VHD), full body digital x-ray of cadavers (Lodox® Statscan® images) combined with palpating landmarks on peers and the cadaver, as well as the use of collaborative, contextual and self-directed learning. Nineteen of these studies were published in the period from 2006 to 2013. The 31 papers covered evidence-based and clinically-applied surface anatomy. The percentage of surface anatomy in textbooks' contents ranged from 0 to 6.2 with an average of 3.4%. The number of medical illustrations on surface anatomy varied from 0 to 135. In conclusion, although there has been a progressive increase in publications addressing methods used in teaching surface anatomy over the last six to seven years, most anatomy textbooks do not provide students with adequate information about surface anatomy. Only three textbooks provided a solid explanation and foundation of understanding surface anatomy. © 2013 American Association of Anatomists. Source


Alothman O.Y.,King Saud University
Advances in Materials Science and Engineering | Year: 2012

Different series of high density Polyethylene/Ethylene Vinyl Acetate (HDPE/EVA) blends were prepared via melt blending in a corotating intermeshing twin screw extruder. The effects of VA percentage and EVA loading ratio on the thermal, rheological viscoelastic, mechanical, and fracture toughness of the blends were analyzed. The results showed that the addition of EVA to HDPE reduces the thermal, elastic, and viscoelastic properties of the blends. The microscopic examination of the fracture surface confirmed the ductile fracture of HDPE/EVA blends for all blend ratios and VA percentages. Increasing the EVA ratio and VA content caused a significant reduction in the blend crystallinity but had no significant effect on melting temperature. The complex viscosity increased with increasing the percentage of EVA due to the restriction of molecular mobility and reduction of free volume, induced by the addition of EVA. The storage modulus decreased with increasing the EVA ratio and temperature, while it increased with increasing the frequency. Young's modulus, yield strength, and fracture strain decreased with increasing the EVA ratio. Similarly, the fracture toughness decreased proportional to the EVA percentage. Finally the results indicated that the VA content has significant effects on the mechanical, thermal, and dynamic properties of HDPE/EVA blends. © 2012 Othman Y. Alothman. Source


Sabir S.,King Saud University
Critical Reviews in Environmental Science and Technology | Year: 2015

The hazard of oil pollution has increased with the growth of industrial development and exploration, production, and refining of oil. Due to the recent increase in the volume of oily wastewater worldwide, the outcome and effect of discharging contaminated water into the environment have become significant issues of environmental concern. Thus, the treatment of oily water is critical for environmental protection. Oily water is conventionally treated through different physical, chemical, and biological methods. However, most of the conventional treatment technologies fail to remove small suspended oil content and dissolved elements; moreover, many chemical treatments involve high initial and/or running costs and lead to the production of hazardous sludge, which is released into offshore platforms because of space constraints. This highlights the need for compact physical and chemical systems. Among the various methods proposed for the treatment of oily water, adsorption is an attractive option because of its excellent oil-removing ability, eco-friendliness, cost-effectiveness, easy availability, feasibility, universal applicability, and relieves operation. The present article describes the effectiveness of hydrophobic adsorbents, their application to oil-spill cleanup, and the toxic effects of oily water on human health and the environment. In addition, we have also attempted to elucidate the available cost-effective adsorbent techniques and future perspectives of economical adsorbents for oily water treatment. Copyright © 2015 Taylor & Francis Group, LLC. Source


Khan M.I.,King Saud University
Construction and Building Materials | Year: 2012

High performance concrete (HPC) is defined in terms of both strength and durability performance under anticipated environmental conditions. HPC can be manufactured involving up to 10 different ingredients whilst having to consider durability properties in addition to strength. The number of ingredients and the number of properties of HPC, which needs to be considered in its design, are more than those for ordinary concrete. Therefore, it is difficult to predict the mix proportions and other properties of this type of concrete using statistical empirical relationship. An alternative approach is to use an artificial neural network (ANN). Based on the experimentally obtained results, ANN has been used to establish its applicability to the prediction and optimization of mix proportioning for HPC. It was demonstrated that mix proportioning for HPC can be predicted using ANN. However, some trial mixes are necessary for better performance and elimination of material variability factors from place to place. ANN procedure provides guidelines to select appropriate material proportions for required strength and rheology of concrete mixes and will reduce the number of trial mixes. © 2011 Elsevier Ltd. All rights reserved. Source


Foda M.A.,King Saud University
JVC/Journal of Vibration and Control | Year: 2012

The focus of this work is to develop a direct and exact approach using the Green's function to suppress the transverse vibration of an axially moving string supported by two eyelets. This is achieved by introducing suitable control forces (using actuators) or passive elements to be located at some chosen locations along the span between the eyelets. A scheme is proposed for evaluating the control forces and their locations to suppress the vibration and correspondingly decrease the generated noise. The variation of the running speed, different end supports and damping are taken into consideration. © 2011 The Author(s). Source


Deraz N.M.,King Saud University
International Journal of Electrochemical Science | Year: 2013

The crystallite size, lattice constant and unit cell volume of copper- alumina nano- composite were determined by X-ray diffraction (XRD) technique. Various phases of copper supported on alumina were prepared in this study by combustion route. The morphological properties of as prepared copper- alumina were studied by scanning electron micrographs (SEM) technique. The results revealed that the combustion method led to formation of different copper phases with various valences depending upon the amount of fuel. The change in amount of fuel affects formation and crysatllinity of products. The as synthesized materials have spongy and fragile characteristics. © 2013 by ESG. Source


Napoli C.,The Second University of Naples | Paolisso G.,The Second University of Naples | Casamassimi A.,The Second University of Naples | Al-Omran M.,King Saud University | And 4 more authors.
Journal of the American College of Cardiology | Year: 2013

Nitric oxide (NO) has been suggested to be a pathophysiological modulator of cell proliferation, cell cycle arrest, and apoptosis. In this context, NO can exert opposite effects under diverse conditions. Indeed, several studies have indicated that low relative concentrations of NO seem to favor cell proliferation and antiapoptotic responses and higher levels of NO favor pathways inducing cell cycle arrest, mitochondria respiration, senescence, or apoptosis. Here we report the effects of NO on both promotion and inhibition of cell proliferation, in particular in regard to cardiovascular disease, diabetes, and stem cells. Moreover, we focus on molecular mechanisms of action involved in the control of cell cycle progression, which include both cyclic guanosine monophosphate-dependent and -independent pathways. This growing field may lead to broad and novel targeted therapies against cardiovascular diseases, especially concomitant type 2 diabetes, as well as novel bioimaging NO-based diagnostic tools. © 2013 American College of Cardiology Foundation. Source


Al-Hudhud G.,King Saud University
Computers in Human Behavior | Year: 2015

A multi agent system (MAS) is a complex system composed of heterogeneous agents each has a number of concern that are cross-cutting such as mobility, learning, collaboration, adaptation, interaction and autonomy. MASs are currently designed to be superimposed on object oriented designs so that it can be possible to separate these concerns in order to improve reusability and maintainability. Hence, aspect-oriented software development (AOSD) exists to cope with complexity of software development for the purpose of separating functionality that are not handled by other software development. Following this line of thought, AOSD is considered for developing aspects for team learning management system; that allows recognizing learner's learning preferences and associated learning style in the learning environment. This paper presents an approach to move from object oriented eTutor to agent oriented eTutor through aspect oriented software development. This transition is being deployed through the implementation level. © 2015 Elsevier Ltd. Source


Atif M.,King Saud University | Atif M.,National Institute of Laser and Optronics
Laser Physics Letters | Year: 2012

The experimental results described elaborate a micro-spectroscopic technique to record the laser-induced fluorescence emission of the photodynamic therapy (PDT) photosensitizer meso tetra hydroxy phenyl chlorin (mTHPC - Foscan) from micron-scale locations within individual keratinocytes. The technique provided the ability to analyze mTHPC fluorescence dynamics in single fixed cells. The system has been utilized to monitor mTHPC fluorescence accumulation and mTHPC photobleaching dynamics during continuous laser exposure at different excitation powers. These parameters have been examined in normal keratinocytes (representing normal skin cells). The rate of photobleaching, when plotted as a function of light dose follows an inverse-dose-rate dependence. Specifically, the bleaching rate at the highest incident laser powers applied is limited by oxygen availability, which significantly increases the (1/e) bleaching dose. No photoproduct emission was evident across the spectral region investigated. These results are in qualitative agreement with previous studies which demonstrate that the photodynamic dose delivered during light exposure is critically dependent upon local fluence-rate and oxygen partial pressure. © 2012 by Astro, Ltd. Source


Alahmed Z.A.,King Saud University
Solid State Sciences | Year: 2013

First-principles density functional theory was used to investigate effects of in-plane strains on the structural, electronic, and optical properties of wurtzite cadmium selenide (CdSe). The results of this work show some interesting properties of this material under finite strains that do not exist in the bulk unstrained regime. The structural deformation produced by increasing the in-plane strain, including the internal parameter u, was examined. The result shows that the structure undergoes a phase transition at a strain of 9.3% due to an extraordinary increase of the internal parameter u. By analyzing the electronic band structure using the modified Becke-Johnson approximation (mBJ), a direct-indirect band gap transition at an in-plane strain of 9.3% was found. Additionally, optical dielectric constants, reflectivity, and refractive index were calculated at different values of the strain. These results indicate that, by controlling the CdSe biaxial in-plane lattice constant (for example, by epitaxial growth on an appropriate substrate), the electronic and optical properties can be tuned for specific device applications. © 2013 Elsevier Masson SAS. All rights reserved. Source


Mahboob S.,King Saud University
Life Science Journal | Year: 2013

This review summarizes the current information on the contribution of heavy metals as a result of pollution to the development of oxidative stress in fish. Metals are considered as important toxic pollutants and there is an extensive literature about their accumulation in aquatic ecosystems. Globally, there is now abundant evidence that anthropogenic activities have contaminated the environment with heavy metals from multiple sources. Heavy metals are important inducers of oxidative stress in aquatic animals, promoting formation of reactive oxygen species.Reactive oxygen species (ROS) are an unenviable part of aerobic life. The potential of oxygen free radicals and other reactive oxygen species (ROS) to damage tissues and cellular components, called oxidative stress, in biological systems has become a topic of concern for environmental pollution studies. Their steady-state concentration is a balance between production and elimination providing certain steady-state ROS level. The balance between prooxidant endogenous and exogenous factors (i.e., environmental pollutants) and antioxidant defenses (enzymatic and nonenzymatic) in biological systems can be used to assess the toxic effects under stressful environmental conditions, especially oxidative damage caused by various groups of chemical pollutants. Increased levels of reactive oxygen species lead to oxidative damage including lipid peroxidation, protein and DNA oxidation, and enzyme inactivation. The components of the antioxidant defence are used as a biochemical markers of oxidative stress. This knowledge extends to specific applications in fish because of their sensitivity to oxidative pollutants, their filtration capacity, and their potential for environmental toxicology studies. Source


Al Mijalli M.H.,King Saud University
European Journal of Scientific Research | Year: 2011

Real time medical imaging applications require efficient algorithms. The Field Programmable Gate Arrays (FPGAs) have the ability to realize such applications in terms of speed, less power dissipation and covering less area. This paper presents the FPGA based truncated multipliers delay study; implemented on Spartan-3AN, Virtex-E, Virtex and Virtex-5 FPGAs using Very high speed integrated circuit Hardware Description Language (VHDL). The delay study was analysed using analysis of variance (ANOVA) method using the software Statistical Package for Social Science (SPSS). The one way ANOVA method followed by post hoc Tukey's test using the software SPSS with a .05 significance level was used to compare the FPGA devices. The latency study of truncated multipliers using Virtex-5 FPGA demonstrates excellent results than Spartan-3AN, Virtex- E, and Virtex FPGA devices. Multiple comparison tests revealed that the differences between the FPGA devices are significant with a 95% confidence level. A linear trend line also illustrates that the mean delay time for virtex-5 for the 4×4, 6×6, 8×8 and 12×12 truncated multiplier consistently increases. The R-squared value for Virtex-5 is 0.977. The linear behaviour of the Virtex-5 FPGA device illustrates that it is a promising device for technological applications such as medical imaging using truncated multipliers. © EuroJournals Publishing, Inc. 2011. Source


Nano-crystalline magnesia doped nickel ferrite powders have been synthesized by the combustion route. The structural, morphological and magnetic properties of the products were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and vibrating sample magnetometer (VSM). X-ray analysis showed that all samples were cubic spinel. The increase in magnesia concentration resulted in a decrease in the average crystallite size, lattice constant, unit cell volume, X-ray density, ionic radii, the distance between the magnetic ions and bond lengths on tetrahedral sites and octahedral sites of the as prepared ferrite. The combustion method led to formation of spongy and fragile network structure. Increasing amounts of magnesia brought about remarkable changes in the microstructure and porosity of nickel ferrite. Doping of nickel ferrite by magnesia led to a decrease in its saturation magnetization. The minimum saturation magnetization value of nickel ferrite due to the doping 1 wt.% MgO attained 44.18 emu/g. © 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source


Ola M.S.,King Saud University
Biochemical and Biophysical Research Communications | Year: 2014

Hyperglycemia and impaired insulin signaling are considered as major factors in the retinal pathology in diabetic retinopathy (DR). Numerous reports support that these two factors damage retinal glial as well as neuronal cells early in diabetes. However, it is not known whether diabetic induced hyperglycemia causes a depression to the insulin signaling. In this study we utilized a well characterized cultured Muller cells (TR-MUL) where we found a high expression of insulin receptor molecules. TR-MUL Cells were treated with high glucose, glutamate and hydrogen peroxide, and activated with insulin. Following treatments, cell lysates were analyzed by immunoblotting experiments for insulin receptor (IRβ) and insulin receptor substrate (IRS1). In addition, cell lysates were immunoprecipitated using antibodies against insulin receptor proteins to analyze tyrosine phosphorylation and serine phosphorylation of insulin receptor proteins. Results indicate that hyperglycemia did not affect the expression of insulin receptor proteins in cultured TR-MUL cells. Although, hyperglycemia seems to inhibit the interaction between IRS1 and IRβ. Hydrogen peroxide increased the tyrosine phosphorylation of insulin receptor proteins but excess glutamate could not affect the insulin receptor proteins indicating that glutamate may not cause oxidative stress in TR-MUL cells. Hyperglycemia lowered serine phosphorylation of IRSser632 and IRSser1101 however, IRSser307 was not affected. Thus, hyperglycemia may not affect insulin signaling through tyrosine phosphorylation of insulin receptor proteins but may inhibit the interactions between insulin receptor proteins. Hyperglycemia induced phosphorylation of various serine residues of IRS1 and their influence on insulin signaling needs further investigation in TR-MUL cells. © 2014 Elsevier Inc. All rights reserved. Source


Al-Ahaideb A.,King Saud University
European Journal of Orthopaedic Surgery and Traumatology | Year: 2014

Background: Variable outcomes resulting from the availability of multiple techniques for the treatment of chronic acromioclavicular joint (ACJ) dislocation have led to difficulty in choosing the optimal therapeutic strategy. Accordingly, the authors describe a technique for the treatment of chronic ACJ dislocation and its benefits. Subjects and methods: The authors present a technique for surgically treating chronic ACJ dislocation using the Weaver-Dunn procedure in combination with a commercially available system (TightRope; Arthrex, Naples, FL, USA). Nine patients with chronic ACJ dislocation were surgically treated and postoperative results were evaluated. Results: The patients were followed up for a mean of 20 months. Shoulder function was evaluated using the Constant score, with a mean score of 97 %. Compared with the uninjured side, radiography showed anatomical repositioning in the vertical plane in seven cases and slight loss of reduction in two cases. The procedure provided good functional and subjective results. All patients returned to their pre-injury activity levels. Conclusion: The Weaver-Dunn procedure augmented by the TightRope system appeared to be an effective for treating chronic ACJ dislocation and led to excellent outcomes in terms of return to pre-injury level of function. © 2013 Springer-Verlag. Source


Al-Hudhud G.,King Saud University
Computers in Human Behavior | Year: 2015

The work presented in this paper describes the design for Graduation Project eCoordination System in our department. The proposed eCoordinator provides effective team-team, supervisor-team and coordinator-supervisors-teams collaboration. eCoordinator is an attribute based framework that serves evolving an object oriented software system into agent oriented software system. Nowadays, agent-oriented software development technologies have evolved rapidly; it is emerging as a new paradigm for constructing intelligent more autonomous software systems. Therefore, several methodologies are available and it is difficult to determine the most appropriate methodology for specific project within different domains. This is especially occurs when re-engineering current object oriented software system. The case study is going to be rebuilding a virtual graduation project coordinator in Information Technology Department at King Saud University. © 2015 Elsevier Ltd. Source


Azer S.A.,King Saud University
European Journal of Gastroenterology and Hepatology | Year: 2014

BACKGROUND: With the changes introduced to medical curricula, medical students use learning resources on the Internet such as Wikipedia. However, the credibility of the medical content of Wikipedia has been questioned and there is no evidence to respond to these concerns. The aim of this paper was to critically evaluate the accuracy and reliability of the gastroenterology and hepatology information that medical students retrieve from Wikipedia. METHODS: The Wikipedia website was searched for articles on gastroenterology and hepatology on 28 May 2013. Copies of these articles were evaluated by three assessors independently using an appraisal form modified from the DISCERN instrument. The articles were scored for accuracy of content, readability, frequency of updating, and quality of references. RESULTS: A total of 39 articles were evaluated. Although the articles appeared to be well cited and reviewed regularly, several problems were identified with regard to depth of discussion of mechanisms and pathogenesis of diseases, as well as poor elaboration on different investigations. Analysis of the content showed a score ranging from 15.6±0.6 to 43.6±3.2 (mean±SD). The total number of references in all articles was 1233, and the number of references varied from 4 to 144 (mean±SD, 31.6±27.3). The number of citations from peer-reviewed journals published in the last 5 years was 242 (28%); however, several problems were identified in the list of references and citations made. The readability of articles was in the range of -8.0±55.7 to 44.4±1.4; for all articles the readability was 26±9.0 (mean±SD). The concordance between the assessors on applying the criteria had mean κ scores in the range of 0.61 to 0.79. CONCLUSION: Wikipedia is not a reliable source of information for medical students searching for gastroenterology and hepatology articles. Several limitations, deficiencies, and scientific errors have been identified in the articles examined. © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source


El-Ansary A.K.,King Saud University
BMC complementary and alternative medicine | Year: 2014

BACKGROUND: Reducing exposure to toxic environmental agents is a critical area of intervention. Prenatal or postnatal exposure to certain chemicals has been documented to increase the risk of autism spectrum disorder. Propionic acid (PA) found in some foods and formed as a metabolic product of gut microbiota has been reported to mediate the effects of autism. Results from animal studies may help to identify environmental contaminants and drugs that produce or prevent neurotoxicity, and may thereby aid in the treatment of neurodevelopmental disorders such as autism. The present study investigated the protective and/or therapeutic effects of vitamin D against brain intoxication induced by propionic acid (PPA) in rats.METHODS: Twenty-eight young male Western Albino rats were enrolled in the present study. They were grouped into four equal groups of 7. The control group received only phosphate buffered saline; the oral buffered PPA-treated group received a neurotoxic dose of 250 mg/kg body weight/day for 3 days; and the Vitamin D-protected group received 1000 IU/kg/day of alpha, 25-dihydroxyvitamin D (3) (1, 25-VD) for two weeks, after which the rats were injected with PPA 250 mg/Kg body weight/day for 3 days. The fourth group received PPA 250 mg/Kg body weight/day for 3 days followed by alpha, 25-dihydroxyvitamin D (3) (1, 25-VD) for two weeks (Vitamin D therapeutic effect). Vitamin D and calcium were measured in the plasma of the four studied groups. Serotonin, interferon gamma (IFN-γ), glutathione-s-transferase activity and DNA double helix breaks were assayed in the brain tissue of the rats for all groups.RESULTS: The obtained data showed that the PPA-treated group demonstrated higher plasma vitamin D levels compared to the control rats, together with multiple signs of brain toxicity, as indicated by a depletion of serotonin (5HT), an increase in IFN-γ and inhibition of glutathione-s-transferase activity as three biomarkers of brain dysfunction. Additionally, Comet DNA assays showed remarkably higher tail length, tail DNA % damage and tail moment as a neurotoxic effect of PPA.CONCLUSIONS: Vitamin D showed a greater protective than therapeutic effect on PPA-induced neurotoxicity in rats, as there was a remarkable amelioration of the impaired biochemically measured parameters representing neurochemical, inflammation, and detoxification processes. Source


Alsufyani M.A.,King Saud University
Dermatology Research and Practice | Year: 2012

Subcision is a surgical technique used mostly to manage depressed scars. Over time, many modifications to this surgical technique have been made by various surgeons in order to make it simpler and more effective. We report here a new technique that aims to combine the privilege of the prevention of penetrating the skin beyond the scar and maintaining a horizontal orientation, while taking the advantage of the ergonomics of having the dominant hand parallel to the skin surface and the cylindrical grip of a 3 cc syringe. The purpose of our technique is to make subcision more practical and easier for the surgeon. © 2012 Mohanned A. Alsufyani and Mohammed A. Alsufyani. Source


Al-Qattan M.M.,King Saud University
Journal of Hand Surgery: European Volume | Year: 2015

The aetiology, management, and results of acute rupture of primary flexor tendon repairs in Zones I and II of the fingers in children have not been previously investigated. The author reports on a personal series of 10 children treated over a period of 13 years. The aetiology is different when compared with adults: children less than 5 years of age usually rupture their primary repairs whilst the hand is completely immobilized in a cast; whereas teenagers usually rupture their tendons when falling down while playing. In the current series, direct re-repair was performed without lengthening at the musculo-tendinous junction, and no free tendon grafts were used. The results were worse than other paediatric series of primary flexor tendon repairs. Using the Strickland-Glogovac criteria, there was only one excellent outcome, the remaining nine being either a good (n = 5) or fair (n = 4) outcome. © 2014 The Author(s). Source


El-Harbawi M.,King Saud University
Environmental Reviews | Year: 2013

The objective of this paper is to provide a comprehensive theoretical review with regard to history, existing approaches, recent developments, major research, associated computational methods, and applications of air quality models. A wide range of topics is covered, focusing on sources of air pollution, primary and secondary pollutants, atmospheric chemistry, atmospheric chemical transport models, computer programs for dispersion modelling, online and offline air quality modelling, data assimilation, parallel computing, applications of geographic information system in air quality modelling, air quality index, as well as the use of satellite and remote sensing data in air quality modelling. Each of these elements is comprehensively discussed, covered, and reviewed with respect to various literature and methods related to air quality modelling and applications. Several major commercial and noncommercial dispersion packages are extensively reviewed and detailed advantages and limitations of their applications are highlighted. The paper includes several comparison summaries among various models used in air quality study. Furthermore, the paper provides useful web sites, where readers can obtain further information regarding air quality models and (or) software. Lastly, current generation of air quality models and future directions are also discussed. This paper may serve as a compendium for scientists who work in air quality modelling field. Some topics are generally treated; therefore, the paper may also be used as a reference source by many scientists working with air quality modelling. © 2013 Published by NRC Research Press. Source


Al-Atawi F.J.,King Saud University
Saudi Journal of Biological Sciences | Year: 2011

This study was conducted to investigate phytophagous and predatory mites associated with vegetable plants in Riyadh, Saudi Arabia. Eight phytophagous and 10 predacious mites were collected from 14 species of vegetable crops covering five major production localities. Out of these 18 mite species, 13 species are new to the mite fauna of Saudi Arabia. In addition, the two species, Tenuipalpus punicae and Agistemus exsertus, are reported for the first time on vegetable crops in Saudi Arabia. For each mite species found, notes on host plant association and occurrence period are given. An illustrated key for the identification of the 18 mite species reported in this study is provided and this can be used to improve the IPM programs by applying the local natural predatory mites in controlling mite pests in Saudi Arabia. © 2011. Source


Al-Jahdali H.,King Saud University
Journal of Medical Case Reports | Year: 2010

Introduction. Hughes-Stovin syndrome is a very rare disease with fewer than 30 cases reported in the literature. The disease is thought to be a variant of Behcet's disease and is defined by the presence of pulmonary artery aneurysm in association with peripheral venous thrombosis. Case presentation. A previously healthy 23-year-old Saudi woman presented with massive hemoptysis a day prior to her admission to our hospital. She had a six-month history of recurrent fever, cough, dyspnea, and recurrent oral ulceration. Contrast-enhanced computed tomography scan of her chest and pulmonary angiogram demonstrated a single right-lower lobe pulmonary artery aneurysm. She underwent thoracotomy and right lower lobe resection. Her postoperative course was complicated by deep vein thrombosis. She also developed headache and papilledema, while a magnetic resonance imaging of her brain suggested vasculitis. Based on these clinical presentations, she was diagnosed and treated with Hughes-Stovin syndrome. Conclusion. The majority of cases of Hughes-Stovin syndrome are reported among men, with only two cases occurring in women. A case of Hughes-Stovin syndrome occurring in a woman is presented in this report. She was treated successfully with multimodality treatment that includes surgery, steroids and cytotoxic agents. © 2010 Al-Jahdali; licensee BioMed Central Ltd. Source


Badr G.,King Saud University | Badr G.,Assiut University
Lipids in Health and Disease | Year: 2013

Background: Delayed wound healing is considered one of the most serious diabetes-associated complications. The presence of replicating organisms such as bacteria within a diabetic's wound is considered one of the most important factors that impair cutaneous wound healing and the potential cellular and/or molecular mechanisms that are involved in the healing process. Defensins, which are anti-microbial peptides, have potent bactericidal activity against a wide spectrum of the bacterial and fungal organisms that are commonly responsible for wound infections. We recently demonstrated that camel whey proteins (WPs) expedite the healing of diabetic wounds by enhancing the immune response of wounded tissue cells and by alleviating some of the diabetic complications. Methods. In the present study, we investigated the effects of WP supplementation on the mRNA and protein expression levels of β-defensin-1 (BD-1), 2 and 3 and subsequently on the wound healing process in a streptozotocin (STZ)-induced diabetic mouse model. In this study, three groups of mice were used (10 mice per group): group 1, the non-diabetic mice (control); group 2, the diabetic mice; and group 3, the diabetic mice that received a daily supplement of undenatured WP (100 mg/kg of body weight) via oral gavage for 1 month. Results: Compared with the non-diabetic control mice, the diabetic mice exhibited delayed wound closure that was characterized by a reduction in hydroxyproline content (indicator of collagen deposition), a marked elevation in free radical levels and a prolonged elevation in the levels of inflammatory cytokines, including interleukin-6 (IL-6), transforming growth factor-beta (TGF-β) and tumor necrosis factor-alpha (TNF-α). Interestingly, compared with the diabetic mice that did not receive WP supplementation, the diabetic mice with WP had an accelerated closure and healing process of their wounds. The WP supplementation also decreased their levels of free radicals and restored their hydroxyproline content; proinflammatory cytokine levels; and expression of BD-1, 2 and 3 in the wounded tissue. Conclusion: WP supplementation may be beneficial for improving the healing and closure of diabetic wounds. © 2013 Badr; licensee BioMed Central Ltd. Source


Hepatitis E Virus (HEV) ORF1 encodes the nonstructural polyprotein wherein a role of PCP-domain in ORF1 proteolysis and/or RNA replication still remains contested. A series of ORF1 mutants of HEV-SAR55 replicon were constructed and tested for viability in S10-3 cells. Six of PCP-'cysteine' (C457A, C459A, C471A, C472A, C481A and C483A) and three 'histidine' (H443L, H497L and H590L) mutants were lethal. Further, a highly conserved 'glycine-triad' (G815-G816-G817) in downstream X-domain, homologous to rubella virus protease-substrate (G1299-G1300-G1301) was identified where two of X-mutants (G816V and G817V) turned lethal. However, all ORF1 sequential nucleotide-mutants conserving the amino acids were viable, which clearly showed post-translational regulation of HEV replication by PCP- and X-domains. Moreover, while vector-expressed ORF1-fusion polyprotein yielded a ~191kDa band in vitro, it produced ~78 and ~35kDa fragments ex vivo. Collectively, the indispensability and functional effects of 'PCP-catalytic' and 'X-substrate' residues on HEV replication strongly supported a viral protease. © 2013 Elsevier B.V. Source


Vohra M.S.,King Saud University
International Journal of Occupational Medicine and Environmental Health | Year: 2011

Introduction: This study was conducted to correlate the personal formaldehyde (FA) exposure levels of instructors and students with the indoor FA concentrations in gross anatomy laboratory at King Saud University. The personal FA levels of instructors and students are higher than the indoor FA concentration in the gross anatomy laboratory. Materials and Methods: The gross anatomy laboratory at college of medicine, King Saud University Riyadh, was observed for indoor FA concentration and the personal exposure levels of instructors and the medical students during the 4th, 10th and 14th weeks of the dissection sessions. All air samples were collected by the diffusive sampling device and analyzed by using high performance liquid chromatography (HPLC). Results: The personal exposure level of FA was higher than the indoor concentration, and the personal exposure levels of instructors were higher than that of the students. The concentration of FA was also higher in the center of the room than the corners and near the doors. Conclusion: Both the indoor FA concentrations and personal FA exposure levels are higher near the dissecting table than at locations away from it during the gross anatomy laboratory sessions. Thus, the instructors and students are exposed to the higher concentration of FA than the general population. © Nofer Institute of Occupational Medicine, Łödz̈, Poland. Source


Al-Qattan M.,King Saud University
Annals of Plastic Surgery | Year: 2013

In isolated high radial nerve palsy, it is traditionally taught that one should not use both wrist flexors for tendon transfers. Over the last 17 years, the author has encountered 4 unusual cases of high radial nerve palsy with concurrent direct injury to the pronator teres, flexor digitorum superficialis, and the palmaris longus in the proximal forearm. In these cases, the author used both wrist flexors, namely, the flexor carpi radialis to restore wrist extension and the flexor carpi ulnaris to restore finger/thumb extension as well as thumb radial abduction. Despite the major loss of wrist flexion, all patients had a good overall function as per the modified Bincaz scale. It was concluded that this "double wrist flexor" transfer remains to be an acceptable option for high radial nerve palsy when the pronator teres, flexor digitorum superficialis, and the palmaris longus tendons are not available. Copyright © 2013 by Lippincott Williams & Wilkins. Source


Mohamed S.,King Saud University
Acta Endocrinologica | Year: 2014

Introduction. Leprechaunism is a rare autosomal recessive condition characterized by dysmorhic features, growth failure and disordered glucose homeostasis. Case report. A term infant was born to a first cousin, who previously lost a baby with Leprechaunism. Pregnancy and delivery were uneventful. Birth weight, length and head circumference were all below the third centile. Clinical examination at birth reveals large low set ears, depressed nasal bridge, gingival hyperplasia, prominent nipples, umbilical hernia, lipodystrophy, hypertrichosis, and wrinkled loose skin. Examination of the genitalia showed a prominent phallus, posterior fusion of the labioscrotal folds and no palpable gonads. A clinical diagnosis of Leprechaunism was made based on the family history and the clinical phenotype. In addition to the presence of ambiguous genitalia, management of this infant was complicated by poor glycemic control with frequent hyper and hypoglycemic episodes. Insulin was inappropriately high (1626.1 mU/mL, normal 3-17 Mu/mL) when glucose was relatively low (3.2 mmol/L) indicating insulin resistance. ACTH stimulation test confirmed an intact adrenal function with normal 17 hydroxyprogesterone and cortisol. Testosterone and adrenal androgens were normal. Chromosomal study showed 46 XX and MRI abdomen revealed normal pancreas and internal female organs. Accordingly, this infant was assigned as a female. Severe hyper and hypoglycemic episodes responded to introduction of frequent nasogastric formula milk feeding together with insulin glargine. Glycemic control improved with glycated hemoglobin of 8%. Conclusion. This case report illustrates a management challenge of a newborn infant with Leprechaunism, ambiguous genitalia and poor glycemic control and discuss treatment options. Source


Alswat K.A.,King Saud University
Saudi Journal of Gastroenterology | Year: 2013

Non-alcoholic fatty liver disease (NAFLD) is a major cause of liver morbidity and mortality with no proven effective therapy as of yet. Its prevalence is increasing globally in parallel with obesity and metabolic syndrome pandemic. The endocannabinoid (EC) system has been implicated in the pathogenesis of several diseases, including fatty liver diseases. This system refers to the cannabinoid receptors type 1 (CB1) and type 2 (CB2), with both their endogenous ligands and machinery dedicated to EC synthesis and degradation. There is accumulating evidence on the role CB1 as a key mediator of insulin resistance and liver lipogenesis in both animals and humans. On the other hand, CB2 receptors have been shown to promote inflammation with anti-fibrogenic properties. The pharmacological modulation of the EC system activity for the treatment of metabolic syndrome and NAFLD are promising yet premature. The initial limited success due to deleterious central nervous system side-effects are likely to be bypassed with the use of peripherally restricted drugs. Source


Simos T.E.,King Saud University | Simos T.E.,University Sidi Mohammed Ben Abdellah
Journal of Chemical Physics | Year: 2010

In this paper, we introduce new integrators of Newton-Cotes type and investigate the connection between these new methods, differential methods, and symplectic integrators. From the literature, we can see that several one step symplectic integrators have been obtained based on symplectic geometry. However, the investigation of multistep symplectic integrators is very poor. In this paper, we introduce a new numerical method of closed Newton-Cotes type and we write it as a symplectic multilayer structure. We apply the symplectic schemes in order to solve Hamilton's equations of motion which are linear in position and momentum. We observe that the Hamiltonian energy of the system remains almost constant as integration proceeds. © 2010 American Institute of Physics. Source


A fully automated, rapid and highly sensitive HPLC method with automated sample pre-treatment by column-switching system and fluorescence detection has been developed for the trace quantitative determination of the new antidepressant reboxetine (RBX) in human plasma. A simple pre-column derivatization procedure with 7-flouro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-F) reagent was employed. Paroxetine (PXT) was used as an internal standard. Plasma samples containing both RBX and PXT, after filtration, were derivatized by heating with NBD-F in borate buffer of pH 8 at 70 °C for 30 min. The derivatized plasma samples were injected into the HPLC system where an on-line sample clean up was achieved on the pre-treatment column (Co-sense Shim-pack MAYI-ODS) with a washing mobile phase (acetonitrile:2% acetic acid; 40:60, v/v) at a flow rate of 5 mL min-1 for 1 min. After an automated on-line column switching to the analytical Hypersil phenyl 120A column (250 mm × 4.6 mm, 5 μm), the separation of the derivatized RBX and PXT was performed using a mobile phase consisting of sodium acetate buffer (pH 3.5):tetrahydrofuran:acetonitrile (55:35:10, v/v/v) at a flow rate of 2.0 mL min-1. The eluted derivatives were monitored by a fluorescence detector set at an excitation wavelength of 470 nm and an emission wavelength of 530 nm. Under the optimum chromatographic conditions, a linear relationship with good correlation coefficient (r = 0.9995, n = 5) was found between the peak area ratio of RBX to PXT and RBX concentration in the range of 2-500 ng mL-1, with limits of detection and quantification of 0.5 and 1.7 ng mL-1, respectively. The intra- and inter-day precisions were satisfactory; the relative standard deviations were 2.25 and 3.01% for the intra- and inter-day precisions, respectively. The accuracy of the method proved as the mean recovery values were 100.11 ± 2.24% and 100.99 ± 2.98% for the intra- and inter-day assay runs, respectively. The proposed method involved simple and minimum sample preparation procedure and short run-time (<12 min) and therefore it can be applied to the routine therapeutic monitoring and pharmacokinetic studies of RBX. © 2009 Elsevier B.V. All rights reserved. Source


Abdalla H.I.,King Saud University
Computers in Human Behavior | Year: 2014

One of the important features of database fragmentation and allocation techniques is the fact that they depend not only on the entries of a database relation, but also on their empirical frequencies of use. Distributed processing is an effective way to improve performance of database systems. However, for a Distributed Database System (DDBS) to function efficiently, fragments of the database need to be allocated carefully at various sites across the relevant communications network. Therefore, fragmentation and proper allocation of fragments across network sites is considered as a key research area in distributed database environment. However, fragments allocation to the most appropriate sites is not an easy task to perform. This paper proposes a synchronized horizontal fragmentation, replication and allocation model that adopts a new approach to horizontally fragment a database relation based on attribute retrieval and update frequency to find an optimal solution for the allocation problem. A heuristic technique to satisfy horizontal fragmentation and allocation using a cost model to minimize the total cost of distribution is developed. Experimental results are consistent with the hypothesis and confirm that the proposed model can efficiently solve dynamic fragmentation and allocation problem in a distributed relational database environment. © 2013 Elsevier Ltd. All rights reserved. Source


Harrag F.,King Saud University
Computers in Human Behavior | Year: 2014

The areas of information retrieval (IR) and information extraction (IE) are the subject of active research for several years in the community of Artificial Intelligence and Text Mining. With the appearance of large textual corpora in the recent years, we felt the need to integrate modules for information extraction in the existing information retrieval systems. The processing of large textual corpora leads needs that are situated at the border of information extraction and information retrieval areas. Our work in this paper, focus on the extraction of the surface information, i.e. information that not requires complex linguistic processing to be categorized. The goal is to detect and extract passages or sequences of words containing relevant information from the prophetic narrations texts. We propose Finite state transducers-based system that solves successively the problem of texts comprehension. Experimental evaluation results demonstrated that our approach is feasible. Our system achieved encouraging precision and recall rates, the overall precision and recall are 71% and 39% respectively. © 2013 Elsevier Ltd. All rights reserved. Source


El Gamal A.A.,King Saud University
Saudi Pharmaceutical Journal | Year: 2010

Marine organisms are potentially prolific sources of highly bioactive secondary metabolites that might represent useful leads in the development of new pharmaceutical agents. Algae can be classified into two main groups; first one is the microalgae, which includes blue green algae, dinoflagellates, bacillariophyta (diatoms)... etc., and second one is macroalgae (seaweeds) which includes green, brown and red algae. The microalgae phyla have been recognized to provide chemical and pharmacological novelty and diversity. Moreover, microalgae are considered as the actual producers of some highly bioactive compounds found in marine resources. Red algae are considered as the most important source of many biologically active metabolites in comparison to other algal classes. Seaweeds are used for great number of application by man. The principal use of seaweeds as a source of human food and as a source of gums (phycocollides). Phycocolloides like agar agar, alginic acid and carrageenan are primarily constituents of brown and red algal cell walls and are widely used in industry. © 2009. Source


Al-Khalifa H.S.,King Saud University
Online Information Review | Year: 2014

Purpose: Designing an effective university mobile website is becoming a necessity for universities. With the increasing percentage of students using smart phones to research colleges and universities, many university websites worldwide are moving towards addressing mobile needs. The purpose of this paper is to provide a comprehensive mobile university evaluation framework that can be used to assess how universities' websites respond to the increasing demand for the mobile web, and also to identify trends and gaps in current services provided in universities' mobile websites. Design/methodology/approach: A framework was developed and applied to a set of 35 universities' mobile websites worldwide. The framework consists of four categories: interface, navigation, content and services offered, and technical aspects. Findings: Evaluation findings show that most universities' mobile websites performed well in terms of mobile-friendliness and functionality; however, suggestions for future improvements are given. Originality/value: No previous evaluation studies of this kind have been conducted. Moreover, this study provides an evaluation framework dedicated to the assessment of universities' mobile websites. © Emerald Group Publishing Limited 1468-4527. Source


Al-Hudhud G.,King Saud University
Computers in Human Behavior | Year: 2014

Speech interaction systems are currently highly demanded for quick hands-free interactions. Conventional speech interaction systems (SISs) are trained to the user's voice whilst most modern systems learn from interaction experience overtime. However, because speech expresses a human computer natural interaction (HCNI) with the world, SIS design must lead to interface computer system that can receive spoken information and act appropriately upon that information. In spite of significant advancements in recent years SISs, there still remain a large number of problems which must be solved in order to successfully apply the SISs in practice and also comfortably accepted by the users. Among many other problems, problems of devising and efficient modeling are considered the primary and important step in the speech recognition deployment in hands-free applications. Meanwhile, the brain-computer interfaces (BCIs) allow users to control applications by brain activity. The work presented in this paper emphasizes an improved implementation of SIS by integrating BCI in order to associate the brain signals for a list of commands as identification criteria for each specific command for controlling the wheelchair with spoken commands. © 2013 Elsevier Ltd. All rights reserved. Source


Ogbuehi K.C.,King Saud University
Clinical Ophthalmology | Year: 2012

Background: The intraocular pressures and biomechanical parameters measured by the ocular response analyzer make the analyzer a useful tool for the diagnosis and management of anterior segment disease. This observational study was designed to investigate the effect of topical anesthesia on the parameters measured by the ocular response analyzer: corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc). Methods: Two sets of measurements were made for 78 eyes of 39 subjects, approximately 1 week apart. In session 1, each eye of each subject was randomized into one of three groups: polyvinyl alcohol (0.5%), tetracaine hydrochloride (0.5%), or oxybuprocaine hydrochloride (0.4%). In session 2, eyes that were in the polyvinyl alcohol group in session 1 were assigned to the tetracaine group, those in the tetracaine group in session 1 were assigned to oxybuprocaine group, and those in the oxybuprocaine group in session 1 were assigned to the polyvinyl alcohol group. For both sessions, each subject first had his or her central corneal thickness assessed with a specular microscope, followed by measurements of intraocular pressure and corneal biomechanical parameters with the Ocular Response Analyzer. All measurements were repeated for 2 minutes and 5 minutes following the instillation of either polyvinyl alcohol, tetracaine, or oxybuprocaine. The level of statistical significance was 0.05. Results: Polyvinyl alcohol, tetracaine hydrochloride, and oxybuprocaine hydrochloride had no statistically significant (P > 0.05) effect on any of the biomechanical parameters of the cornea. There was no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) 2 minutes after the eye drops were instilled in either session. Five minutes after the eye drops were instilled, polyvinyl alcohol showed no statistically significant effect on either IOPg (P > 0.05) or IOPcc (P > 0.05) in either session. Oxybuprocaine and tetracaine caused statistically significant (P < 0.05) reductions in IOPg in session 1, but only tetracaine had a significant (P < 0.05) effect in session 2. Tetracaine also caused a statistically significant (P < 0.05) reduction in IOPcc in session 1. Conclusion: The statistically significant effect of topical anesthesia on IOPg varies with the anesthetic used, and while this effect was statistically significant in this study, the small effect is probably not clinically relevant. There was no effect on any of the biomechanical parameters of the cornea. © 2012 Ogbuehi, publisher and licensee Dove Medical Press Ltd. Source


Purpose: To evaluate the efficacy of microsurgical two-suture single-armed longitudinal intussusception vasoepididymostomy for patients with obstructive azoospermia (OA) attending our institution. Methods: The study enrolled all patients with OA due to epididymal obstruction who had undergone microsurgical two-suture single-armed longitudinal intussusception vasoepididymostomy in the study hospital from July 2009 to November 2012. All procedures were performed by a single surgeon in a university teaching hospital. The inclusion criteria include: documented azoospermia in at least two consecutive semen samples collected 6 weeks apart, with normal ejaculate volume and semen pH. All patients had at least one normal-sized testis and normal FSH levels. All patients had had testicular biopsies to confirm active spermatogenesis. Results: Twenty-two patients with OA due to epididymal obstruction had undergone 22 microsurgical vasoepididymostomy procedures. The mean age of patients and their female partners was 31 and 25 years, respectively. All procedures were performed by Monoski’s two single-armed suture longitudinal intussusception techniques. The mean operating time of unilateral and bilateral procedures was 145 and 214 min, respectively. The median duration of follow-up was 18 (range, 6–30) months. The overall patency rate was 59 %; being 50 and 70 % for unilateral and bilateral procedures, respectively. The overall paternity rate was 36 %. Natural pregnancy was achieved in three cases, and assisted reproduction was used in five using fresh ejaculated semen. Conclusions: Two-suture single-armed longitudinal intussusception microsurgical vasoepididymostomy is a feasible option for couples with male factor infertility due to epididymal OA. Reasonable patency outcomes were achieved in the present series of cases. Individualized counseling, with expectations based on obstructive etiology and anticipated surgical outcomes, should be offered to couples before resorting to assisted reproduction. Longer follow-up is required to ascertain long-term patency, pregnancy outcomes, and late failures. © 2014, Springer Science+Business Media Dordrecht. Source


Hedrich R.,University of Wurzburg | Hedrich R.,King Saud University | Marten I.,University of Wurzburg
Molecular Plant | Year: 2011

The most prominent ion channel localized in plant vacuoles is the slow activating SV type. Slow vacuolar (SV) channels were discovered by patch clamp studies as early as 1986. In the following two decades, numerous studies revealed that these calcium- and voltage-activated, nonselective cation channels are expressed in the vacuoles of all plants and every plant tissue. The voltage-dependent properties of the SV channel are susceptible to modulation by calcium, pH, redox state, as well as regulatory proteins. In Arabidopsis, the SV channel is encoded by the AtTPC1 gene, and even though its gene product represents the by far largest conductance of the vacuolar membrane, tpc1-loss-of-function mutants appeared not to be impaired in major physiological functions such as growth, development, and reproduction. In contrast, the fou2 gain-of-function point mutation D454N within TPC1 leads to a pronounced growth phenotype and increased synthesis of the stress hormone jasmonate. Since the TPC1 gene is present in all land plants, it likely encodes a very general function. In this review, we will discuss major SV channel properties and their impact on plant cell physiology. © 2011 The Author. Source


Alshatwi A.A.,King Saud University
Food and Chemical Toxicology | Year: 2010

Diet plays an important role in DNA methylation, synthesis, and repair; intake has been associated with breast cancer. The folate-metabolizing enzyme, methylenetetrahydrofolate reductase (MTHFR) is polymorphic at nucleotides 677 (C → T), resulting in allozymes with altered activity and is thus believed to cause interindividual differences in cancer risk susceptibility. I evaluated this polymorphism and its effect on the food intake and breast cancer risk association in a population-based case-control study of 100 breast cancer cases and 100 controls using a real-time PCR based assay. All subjects completed in-person interviews, which included a food-frequency questionnaire. Unconditional logistic regression models were used to calculate odds ratios and their 95% confidence intervals, after adjusting for potential confounding factors. Cases and controls were similar in the distribution of. MTHFRpolymorphisms at codon 677 (41.4% cases and 41.8% controls carried the. Tallele). An inverse association of breast cancer risk with food intake was observed in all genotype groups, particularly among subjects with the. 677TTgenotype. Compared with those with the. 677CCgenotype and high food intake frequency, the adjusted odds ratios (95% confidence intervals) associated with low food intake were 1.94 (1.15-3.26), 2.17 (1.34-3.51), and 2.51 (1.37-4.60) for subjects who had. CC,. CT, and. TTgenotypes (Pfor interaction, 0.05). Results of this study suggest that the. MTHFR C677T polymorphism may modify the association between dietary intake and breast cancer risk. © 2010 Elsevier Ltd. Source


Sherif E.-S.M.,King Saud University
International Journal of Electrochemical Science | Year: 2011

The effects of 5-(3-aminophenyl)-tetrazole (APT as a corrosion inhibitor for Mg-Mn alloy after its immersion in naturally aerated stagnant Arabian Gulf water (AGW) for 1 h and 150 h have been reported. The study has been carried out using a combination of electrochemical and gravimetric measurements along with scanning electron microscope (SEM) and X-ray energy dispersive (EDX) investigations. Electrochemical measurements showed that the corrosion of Mg-Mn alloy in AGW decreases with increasing exposure time as well as in the presence of APT and the increase of its concentration. Weight-loss tests after varied exposure intervals proved that the corrosion rate of the alloy decreases with increasing time and APT content. The SEM and EDX investigations revealed that APT molecules inhibit the corrosion of Mg through repairing the weak areas on its surface, which leads to increasing the corrosion resistance for the alloy against the corrosive attack of AGW. © 2011 by ESG. Source


Awad E.,King Saud University
Optics Express | Year: 2015

In future high capacity multicore optical fiber (MCF) networks, signal-processing devices should be able to manipulate data without sacrificing network capacity or MCFs advantages. Thus, it is crucial to have high performance novel devices that can be connected directly to MCFs without conversion to conventional single-core fibers. In this work, a novel Y-splitter for multicore optical fibers is proposed and numerically demonstrated for the first time. The splitter can directly split the power of input MCF cores by 50/50 splitting-ratio into two output MCFs cores. The splitter principle of operation mainly depends on novel double-hump graded-index (DHGI) profile that can space-division split (SDS) optical power by half. Both finite-difference-time-domain and eigenmodeexpansion simulations are performed to design, verify, and characterize performance of Y-splitter. It shows wideband operation over the S, C, L, U-bands with polarization insensitivity. It also demonstrates high performance with reasonable insertion-loss, in addition to very low excess-loss and return-loss. Moreover, the splitter shows good performance tolerance to both MCF and design parameters variations. © 2015 Optical Society of America. Source


Sherif E.-S.M.,King Saud University | Erasmus R.M.,University of Witwatersrand | Comins J.D.,University of Witwatersrand
Electrochimica Acta | Year: 2010

The corrosion of single crystal pure iron in 3.5% NaCl solutions and its inhibition by 3-amino-5-mercapto-1,2,4-triazole (AMTA) have been studied using in situ and ex situ Raman spectroscopy, cyclic voltammetry (CV), open-circuit potential (OCP), potentiodynamic polarization (PDP), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. CV experiments indicated that the iron electrode in the chloride solution alone showed an anodic peak at ∼-650 mV after the 5th cycle shifted to ∼-610 mV after the 20th cycle; another cathodic peak appeared at ∼-990 mV. In the presence of 1.0 mM AMTA, these two peaks shifted to ∼550 and -1050 mV, respectively. OCP, PDP, CA and EIS revealed that the presence of AMTA and the increase of its concentration move the corrosion potential to more positive values and decrease both the corrosion current and corrosion rate. This effect also increases with increasing the immersion time of iron electrode to 24 h in the test electrolyte. In situ and ex situ Raman investigations confirmed that the addition of AMTA molecules to the chloride solution strongly inhibits the iron corrosion through their adsorption onto the surface blocking its active sites and preventing its corrosion. © 2010 Elsevier Ltd. All rights reserved. Source


Ghoniem M.,King Saud University
International Journal of Conservation Science | Year: 2011

This paper presents the results of scientific examinations carried out on an Egyptian bronze statue discovered buried in Sais. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) were used to understand the corrosive morphological characteristics of the patina, to investigate the corrosion products, analyze the elementary composition of the statue and to identify the corrosive factors with effects on the alteration processes. The results indicated that the statue was made of bronze alloy, with copper as the main element, besides lead and tin. Three layers of alteration products with various composition and morphology covered the substrate of the bronze alloy. XRD results indicated that the statue was subjected to many corrosive ions such as sulfur and chloride, and buried in wet soil, rich in oxygen and carbon. This study provides useful information for the restoration and protection of the statue. Source


Kamath K.P.,Peoples Dental Academy | Anil S.,King Saud University
World Journal of Gastroenterology | Year: 2014

Helicobacter pylori (H. pylori) infection is one of the most common bacterial infections in humans. Although H. pylori may be detected in the stomach of approximately half of the world's population, the mechanisms of transmission of the microorganism from individual to individual are not yet clear. Transmission of H. pylori could occur through iatrogenic, fecal-oral, and oral-oral routes, and through food and water. The microorganism may be transmitted orally and has been detected in dental plaque and saliva. However, the role of the oral cavity in the transmission and recurrence of H. pylori infection has been the subject of debate. A large number of studies investigating the role of oral hygiene and periodontal disease in H. pylori infection have varied significantly in terms of their methodology and sample population, resulting in a wide variation in the reported results. Nevertheless, recent studies have not only shown that the microorganism can be detected fairly consistently from the oral cavity but also demonstrated that the chances of recurrence of H. pylori infection is more likely among patients who harbor the organism in the oral cavity. Furthermore, initial results from clinical trials have shown that H. pylori -positive dyspeptic patients may benefit from periodontal therapy. This paper attempts to review the current body of evidence regarding the role of dental plaque, saliva, and periodontal disease in H. pylori infection. © 2014 Baishideng Publishing Group Inc. All rights reserved. Source


Simos T.E.,King Saud University | Simos T.E.,University of Peloponnese
Journal of Mathematical Chemistry | Year: 2011

In this paper we introduce a new explicit hybrid Numerov-type method. This method is of fourth algebraic order and has phase-lag and its first two derivatives equal to zero. We present a stability analysis and an error analysis based on the radial Schrödinger equation. Finally we apply the new proposed method to the resonance problem of the radial Schrödinger equation and we present the final conclusion based on the theoretical analysis and numerical results. © 2011 Springer Science+Business Media, LLC. Source


Alzahrani S.,King Saud University | Mohammad A.W.,National University of Malaysia
Journal of Water Process Engineering | Year: 2014

This review provides insight into the implementation of membrane technology in the petroleum industry for treating produced water that is generated from conventional oilfields in upstream and downstream processes. The ever-evolving and increasingly stringent regulatory standards for discharging produced water pose colossal environmental and economic implications because the bulk of this produced water is disposed into the environment. Thus, a review of the implementation of membrane technology for produced water treatment could contribute to the knowledge required for the increased introduction of scaled-up membrane technology in the petroleum industry. This review encompasses the capabilities and performance optimization possibilities of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membranes. The level of applications that these membrane technologies might attain within the petroleum industry were determined, and these implementations were correlated with the purpose, performance efficiency, treatment system configurations, necessary pretreatment procedures, quality of treated produced water, fouling occurrence and control, foulants, cleaning procedures, raw produced water content, potential challenges with corresponding applied solutions, and economic factors. This review also maps current and future trends and provides a perspective on the outlook for advances in novel membrane applications for produced water treatment. © 2014 Elsevier Ltd. Source


According to Chow et al's classification, type I fractures of the middle phalanx have no associated tendon injury or extensive skin loss, which required reconstruction. Despite the favorable soft-tissue conditions, a rate of poor outcome as 25% has been observed, and the reason for this is unknown. The aim of this study is to test our hypothesis that type I fractures may be subclassified into following 2 types: type IA and type IB, based on the absence or presence of concurrent significant "soft-tissue crush," respectively. Type IB fractures are hypothesized to have a worse outcome. Significant soft-tissue crush is diagnosed clinically by the presence of severe swelling and/or superficial skin injury (not requiring reconstruction). In a prospective study, 29 type I extraarticular fractures of the middle phalanx in adult industrial workers were included and classified into the following 2 groups: type IA (n = 16 fingers) and type IB (n = 13 fingers). All were treated with closed reduction and longitudinal Kirschner wire fixation. The outcome in range of motion was measured, and time to return to work was recorded. At final follow-up, the mean total active motion of the injured fingers was 241.3 degrees in group IA and 186.9 degrees in group IB (P < 0.001 by Mann-Whitney U test). Furthermore, group A patients returned to work earlier than group B (15.1 vs. 26.8 weeks, P < 0.001 by Mann-Whitney U test). It was concluded that severe swelling and superficial skin injury significantly affect the outcome of type I extraarticular fractures of the middle phalanx treated by closed reduction and longitudinal Kirschner wire fixation. Copyright © 2012 by Lippincott Williams & Wilkins. Source


Alsuwaida A.O.,King Saud University
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation, Saudi Arabia | Year: 2010

There are no available data about the prevalence of chronic kidney disease (CKD) and its risk factors in the general population of the kingdom of Saudi Arabia. To estimate the prevalence of CKD and its associated risk factors in the Saudi population, we conducted a pilot community-based screening program in commercial centers in Riyadh, Saudi Arabia. Candidates were interviewed and blood and urine samples were collected. Participants were categorized to their CKD stage according to their estimated Modification of Diet in Renal Disease (MDRD3)-based, the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and the presence of albuminuria. The sample comprised 491 (49.9% were males) adult Saudi nationals. The mean age was 37.4 ± 11.3 years. The over-all prevalence of CKD was 5.7% and 5.3% using the MDRD-3 and CKD-EPI glomerular filtration equations, respectively. Gender, age, smoking status, body mass index, hypertension and diabetes mel-litus were not significant predictors of CKD in our cohort. However, CKD was significantly higher in the older age groups, higher serum glucose, waist/hip ratio and blood pressure. Only 7.1% of the CKD patients were aware of their CKD status, while 32.1% were told that they had protein or blood in their urine and 10.7% had known kidney stones in the past. We conclude that prevalence of CKD in the young Saudi population is around 5.7%. Our pilot study demonstrated the feasibility of screening for CKD. Screening of high-risk individuals is likely to be the most cost-effective strategy to detect CKD patients. Source


Rahman A.,Ibra College of Technology | S-Al-Deyab S.,King Saud University
Applied Catalysis A: General | Year: 2014

A review summarizes about the Ni nano catalysts have emerged as a superactive catalysts for reduction reactions particularly acetone reduction to isopropanol and its valued-added products in chemical industry and Ni catalysts is well informed for hydrogenation reactions for decades but reduction which forms an important area of catalytic process to produce fine chemicals in industries. Reduction of acetone has important applications in heat pumps, fuel cells or fulfilling the substantial demand for the production of 2-propanol. Hydrogenation of acetone is carried out with variety of catalysts notably homogeneous catalysts such as Iridium, Ru complexes etc and heterogeneous catalysts such as Raney Nickel, Raney Sponge, Ni/Al2O3, Ni/SiO2, Ni or Ni, (or supported on SiO2 or MgO) and r-NiMg Al layered double hydroxide. The major products are typically 2-propanol, methyl isobutyl ketone. Nano catalysts are being developed for actone reduction like Ni maleate, cobalt oxide prepared in organic solvents. These catalysts process can be applied for other commercial catalytic process replacing the old one to prepare hollow nanospheres of other materials for catalytic applications. The author summarizes a mini review on acetone hydrogenation under different conditions with various Ni nano heterogeneous catalysts studied so far in literature and new strategies to develop economic and environmentally friendly approach. © 2013 Elsevier B.V. All rights reserved. Source


Elsafi S.H.,King Saud University
Alexandria Engineering Journal | Year: 2014

Heavy seasonal rains cause the River Nile in Sudan to overflow and flood the surroundings areas. The floods destroy houses, crops, roads, and basic infrastructure, resulting in the displacement of people. This study aimed to forecast the River Nile flow at Dongola Station in Sudan using an Artificial Neural Network (ANN) as a modeling tool and validated the accuracy of the model against actual flow. The ANN model was formulated to simulate flows at a certain location in the river reach, based on flow at upstream locations. Different procedures were applied to predict flooding by the ANN. Readings from stations along the Blue Nile, White Nile, Main Nile, and River Atbara between 1965 and 2003 were used to predict the likelihood of flooding at Dongola Station. The analysis indicated that the ANN provides a reliable means of detecting the flood hazard in the River Nile. © 2014 Production and hosting by Elsevier B.V. Source


Baig M.,King Saud University | Khan A.S.,University of Maryland Baltimore County | Choi S.-H.,Sunchon National University | Jeong A.,Sunchon National University
International Journal of Plasticity | Year: 2013

In this paper, the experimental response of oxygen free high conductivity (OFHC) copper under multiaxial loading conditions is presented, along with quasi-static and dynamic response under uniaxial compression loading. The multiaxial experiments were performed under non-proportional loading conditions, where the sample was subjected to uniaxial loading for a predetermined strain followed by biaxial loading. These experimental results provide a comprehensive data set for constitutive modeling of the material response at finite strains, over a wide range of strain-rates and temperatures. The observed strain-rate and temperature dependent responses under uniaxial loading are shown to correlate closely using the Khan-Huang-Liang (KHL) constitutive model; the model is shown to be in close agreement with other published experimental results [Khan, A.S.; Liang, R.; 1999. Behavior of three BCC metal over a wide range of strain rates and temperatures. International Journal of Plasticity 15, 1089-1109; Nemat-Nasser, S.; Li, Y.; 1998. Flow stress of F.C.C polycrystals with applications to OFHC Cu. Acta Materialia 46 (2), 565-577]. This constitutive model is further demonstrated to predict the observed material response accurately, using the material constants determined from uniaxial loading results during proportional and non-proportional loading experiments. The micro-texture characterization of as-extruded, annealed and deformed samples was performed to investigate the effect of tempe