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Riyadh, Saudi Arabia

King Abdulaziz University was founded in 1967 in Jeddah, Saudi Arabia. Designed by English architect John Elliott, it had 2,000 faculty and more than 37,000 students in 2000/2001. Established initially as a private university by a group of businessmen led by Sheikh Muhammad Abu Bakr Bakhashab Pasha and including the writer Hamza Bogary. in 1974 King Abdulaziz University was converted to a public university by a resolution of the Council Ministers of Saudi Arabia . Due to the adoption of the government, the university changed to a large university. According to the latest statistics conducted in 2012 from the Ministry of Higher Education in Saudi Arabia, King Abdulaziz University had 6,148 faculty and total of 132,094 students.The university has number of scientific and theatrical fields of study and the exclusiveness of certain specializations such as Seas science, Nuclear Engineering, and Medical Engineering. Due to Islamic regulations, King Abdulaziz University has separate campuses for male and female students. The university offers an external program and online programs to help students who can not attend classes and to cope with the development in learning by using the technology. Wikipedia.


Katib A.,King Abdulaziz University
Central European Journal of Urology | Year: 2015

Introduction Obesity in men is associated with infertility in numerous studies. The current trend for decline in semen parameters parallels the increasing prevalence of obesity worldwide. In addition to impaired semen quality, fertility among obese men may be affected by sexual dysfunction, endocrino-pathy, aromatization activity, psychological and thermal effects, sleep apnea, leptin and minor toxins, and possibly the inflammatory and obstructive elements of epididymitis pathology. The variable degrees of certainty associated with these causes parallel the levels of supporting evidence. This search aims to shed lights on different conditions that obese men suffer from; as that makes the treatment of infertility more categorized. Material and methods A PubMed search was conducted to identify clinical and pathological mechanisms linking obesity to male infertility. Results Among the myriad of publications reviewed in this paper, impaired spermatogenesis and sexual dysfunction have been shown to drive other variables towards poor fertility potentials. The paper presented a new, detailed flow chart showing more factors and further interactions among conditions leading to infertility. Conclusions The prime hormonal defect in obese men is hypotestosteronaemia, which results in impaired spermatogenesis leading to poor fecundability. Studies have shown that most mechanisms accounting for reduced fertility potentials in overweight men are reversible. © 2015, Central European Journal of Urology. All rights reserved.


El-Shitany N.A.,King Abdulaziz University | El-Shitany N.A.,Tanta University | El-Bastawissy E.A.,Tanta University | El-Desoky K.,Tanta University
International Immunopharmacology | Year: 2014

There are several hypotheses that explain the process of acute inflammation, including free radical overproduction, pro-inflammatory enzyme activation, and release of pro-inflammatory cytokines. In this study, the protective role of ellagic acid against carrageenan-induced acute inflammation was assessed. In addition, the immunomodulatory action, the antioxidant effects, and the role of COX-2 and NF-κB were also investigated. Inflammation was induced by the injection of 100 μl of 1.5% carrageenan solution. Ellagic acid (10, 25, 50, 100 and 200 mg/kg), indomethacin (10 mg/kg), meloxicam (4 mg/kg), and saline, were injected 2 h before carrageenan injection. The percentage inhibition in the paw weight was calculated. Paws, MDA, NO, GSH, IL-1β, TNF-α, IL-10 and NF-κB mRNA expression were estimated. Formalin fixed hind paws were used for histopathological examination and immunohistochemical staining for COX-2 expression. Ellagic acid, meloxicam and indomethacin reduced paws, edema, MDA and NO formation. In addition, all of them restored the depleted GSH contents in the paws. Ellagic acid, meloxicam and indomethacin reduced NF-κB mRNA expression. Ellagic acid ameliorated COX-2 expression; meloxicam inhibited while indomethacin failed. Both ellagic acid and meloxicam increased IL-10 while indomethacin did not. The docking study revealed a high affinity of ellagic acid towards COX-2. Ellagic acid exhibited a potent anti-inflammatory effect against carrageenan-induced inflammation. The mechanisms of ellagic acid induced protection were proved to be due to reduction of NO, MDA, IL-1β, TNF-α, COX-2 and NF-κB expression and induction of GSH and IL-10 production.


Al-Jahdali M.O.,King Abdulaziz University
Acta Zoologica Academiae Scientiarum Hungaricae | Year: 2013

In small samples of the siganid fishes Siganus rivulatus Forsskål et Niebuhr and S. luridus Rüppel (Teleostei) from off the Saudi coast of the Red Sea, some individuals of each fish were found infected with a new intestinal trematode. Those of S. rivulatus were infected with Hexangium saudii sp. n. (Trematoda: Microscaphidiidae), whereas those of S. luridus with Progyliauchen magnacetabulum sp. n. (Trematoda: Gyliauchenidae). Hexangium saudii sp. n. differs clearly from the two valid species of the genus, H. sigani Goto et Ozaki, 1929 (type- species) and H. brayi Hassanine et Gibson, 2005 in many specific characters and is unique in having vitelline follicles arranged in rosette-like groups and short intestinal caeca distant from the testes. Progyliauchen magnacetabulum sp. n. differs clearly from P. sigani Shalaby et Hassanine, 1997, the type and the only species of the genus in many specific characters and is unique in having a much larger ventral sucker, a very long oesophagus (longer than the total body length), a much larger oesophageal bulb and a tubular seminal vesicle.


Abd-Alla A.M.,Taif University | Mahmoud S.R.,King Abdulaziz University | Abo-Dahab S.M.,Taif University
Meccanica | Year: 2012

In this paper, the radial deformation and the corresponding stresses in a homogeneous annular fin for an isotropic material has been investigated. A numerical technique is proposed to obtain the solution of the transient coupled thermoelasticity in an annular fin cylinder with it's base suddenly subject to a heat flux of a decayed exponential function of time. The system of fundamental equations is solved by using an implicit finite-difference method. The present method is a second-order accurate in time and space and unconditionally stable. A numerical method is used to calculate the temperature, displacement and the components of stresses with time t and through the radial of the annular fin cylinder. The results indicate that the effect of coupled thermoelasticity on temperature, stresses and displacement is very pronounced. Comparison is made with the results predicted by the theory of thermoelasticity in the absence of coupled thermoelasticity. © Springer Science+Business Media B.V. 2011.


Hayat T.,Quaid-i-Azam University | Farooq M.,Quaid-i-Azam University | Alsaedi A.,King Abdulaziz University
AIP Advances | Year: 2015

This work addresses the stagnation point flow of carbon nanotubes over an impermeable stretching cylinder with homogeneous-heterogeneous reactions. Modern heat transfer technique (i.e., Newtonian heating) and Carbon nanotubes (CNTs) and water are used to explore the impacts of heat transfer characteristics. Two types of CNTs are used as nanoparticles (i) Single-wall carbon nanotubes (SWCNTs) and (ii) multi-wall carbon nanotubes (MWCNTs). A system of ordinary differential equations is obtained by using suitable transformations. Convergent series solutions are derived via homotopic procedure. Impacts of various pertinent parameters on the velocity, temperature and concentration distributions are discussed graphically. Numerical values of skin friction coefficient and Nusselt number are computed and analyzed. © 2015 Author(s).


Drioli E.,University of Calabria | Drioli E.,Hanyang University | Drioli E.,King Abdulaziz University | Ali A.,University of Calabria | Macedonio F.,University of Calabria
Desalination | Year: 2015

Membrane distillation (MD) has gained significant regard from industrial and academic perspective in recent years, thus the frequency of publications related to the field has greatly accelerated. New perspectives have boosted the research activities related to deeper understanding of heat and mass transport phenomenon, novel applications and fabrication of the membranes specifically designed for MD. New efforts for module fabrication and understanding and control of non-traditional fouling in MD have also been highlighted in the recent literature. The current review summarizes the important and interesting recent developments in MD from the perspectives of membrane fabrication, heat and mass transport phenomenon, nontraditional fouling, module fabrication and applications. The future research directions of interest have also been pointed out. © 2014 Elsevier B.V.


Saddick S.Y.,King Abdulaziz University
Saudi Journal of Biological Sciences | Year: 2014

The present study is designed to demonstrate the ovarian surface epithelial cells' (OSE) estrogen receptor α (ERα) and progesterone receptor (PR) during pregnancy and estrous cycle in rat. Moreover, determination of the levels of plasma progesterone, estradiol, FSH and LH was also made. The levels of plasma progesterone, estradiol, FSH and LH concentrations were determined on days 7 (n= 5), 14 (n= 5), and 21 (n= 5) of pregnancy in three groups of rats and during the estrous cycle (n= 5) using an ELISA kit. Immunohistochemical method for PR and ERα expressions was also made on the ovary. During pregnancy, FSH and LH remained low except at term when LH levels began to increase from 16. ng/ml to 47. ng/ml. Progesterone levels significantly exceeded estradiol values in all pregnant rats with a peak value of 202. ng/ml on day 14. Elevated progesterone levels were associated negatively with LH and estradiol levels during pregnancy. The levels of estradiol surged significantly on day 21. Immunohistochemistry of the ovary showed low levels of OSE cells staining positive for ERα expression. ERα positive cells were absent on day 7 and 14 of pregnancy, only day 21 recorded a very low percentage of immunostaining (0.5%) within the nuclei of OSE cells. On the contrary, immunostaining of PR was not observed within the nuclei of OSE cells in all groups of study. In conclusion, these results may suggest that the progesterone effect during pregnancy seems to be overriding the positive effect of estrogens on OSE cells. High progesterone levels may have a direct negative effect on gonadotropin production and thereby it might inhibit events leading to both follicular development and OSE proliferation. Understanding the factors affecting OSE proliferation may help elucidating the mechanism(s) of assisted diseases such as ovarian cancer. © 2014.


Ahmed M.,King Abdulaziz University | Yamada M.,Kanazawa University
European Physical Journal D | Year: 2012

This paper investigates mode dynamics, operation characteristics and signal distortions associated with sinusoidal modulation of semiconductor lasers. The study is based on intensive integrations of the multimode rate equation model of semiconductor lasers over wide ranges of the modulation frequency and depth. The rate equations take into account both spectral symmetric and asymmetric suppressions of modal gain. The higher harmonic distortions as well as the half harmonic distortion associated with the period doubling effect are investigated. The study is applied to both cases of single-mode and multimode oscillations of the non-modulated laser. The obtained results showed that the modulated signal has six distinct waveforms depending on the modulation conditions; three types have continuous periodic waveforms and the others have periodic pulsing waveforms. The modulated laser is found to oscillate in a single mode under weak modulation where the modulated signal is continuous, whereas the pulsing signals are associated with multimode oscillation. The higher harmonic distortions of single-mode laser are lower than those of two-mode lasers, and become serious at modulation frequencies around the relaxation oscillation frequency. These distortions are highest when the laser output is pulsating and the pulses are superposed by relaxation oscillations. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2012.


Szolnoki A.,Hungarian Academy of Sciences | Perc M.,University of Maribor | Perc M.,King Abdulaziz University
New Journal of Physics | Year: 2015

If rock beats scissors and scissors beat paper, one might assume that rock beats paper too. But this is not the case for intransitive relationships that make up the famous rock-paper-scissors game. However, the sole presence of paper might prevent rock from beating scissors, simply because paper beats rock. This is the blueprint for the rock-paper-scissors game with protection spillovers, which has recently been introduced as a new paradigm for biodiversity in well-mixed microbial populations. Here we study the game in structured populations, demonstrating that protection spillovers give rise to spatial patterns that are impossible to observe in the classical rock-paper-scissors game. We show that the spatiotemporal dynamics of the system is determined by the density of stable vortices, which may ultimately transform to frozen states, to propagating waves, or to target waves with reversed propagation direction, depending further on the degree and type of randomness in the interactions among the species. If vortices are rare, the fixation to waves and complex oscillatory solutions is likelier. Moreover, annealed randomness in interactions favors the emergence of target waves, while quenched randomness favors collective synchronization. Our results demonstrate that protection spillovers may fundamentally change the dynamics of cyclic dominance in structured populations, and they outline the possibility of programming pattern formation in microbial populations. © 2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


The effect of brown marine algae (BMA; Sargassum dentifebium) as alternative feed source for pullets was studied in three processed and at three concentrations in the pullets from 14-42 weeks. The processing forms were sundried brown marine algae (SBMA), sundried and boiled brown marine algae (BBMA) and sundried and autoclaved brown marine algae (ABMA). The concentrations of BMA were 2%, 4% and 6% that composed 10 treatments along with control. Each treatment was replicated 6 times using 30 pullets per treatment. Different criteria on pullets and eggs, including feed intake, body weight, feed conversion efficiency, laying rate and egg mass and quality were studied. Results indicated that BMA could be used up to 6% in the pullets diets from 14 to 42 weeks without adverse effects (P≥0.05) on sexual maturity (139-142 days), laying rate (80.7-87.9%), egg mass (44.99-51.86 g/hen/day), feed conversion ratio (2.468-2.868 kg feed/kg egg) and Haugh unit (82.9-90.6) and shell percentage (8.61-9.87%). Furthermore, egg yolk color and calcium content in eggshell were improved (P≤0.05) by 12.31% and 9.1%, respectively. © A.Z.M. Salem et al., 2014 Licensee PAGEPress, Italy.


A total of 216 laying hens was kept at high ambient temperature (32±4°C, 60% relative humidity) from week 24 to 32 of age. Birds were divided in 8 treatments with 9 replicates of 3 hens each. The groups were fed the same basal diet and submitted to these dietary treatments: control, un-supplemented; green tea (GT), fed GT at 1 g/kg diet; brown marine algae (BMA), fed BMA at 1 g/kg diet; vitamin E (vit. E), fed vit. E at 300 mg/kg diet; GT+BMA, fed GT and BMA at 1 g/kg of each; GT+vit. E, fed GT and vit. E at 1 g and 300 mg/kg, respectively; BMA+vit. E, fed BMA and vit. E at 1 g and 300 mg/kg, respectively. Feeding BMA at 0.1% increased laying rate by 1.2% and improved feed conversion ratio by 5.2% compared to the control. Vitamin E significantly increased shell thickness by 6.6% and Haugh unit by 4.6% compared to the control. In addition, BMA+vit. E or GT+vit. E increased yolk colour by 9.1 and 10.7%, and Haugh unit of stored eggs by 10.9 and 11.1%. Cholesterol of fresh eggs and plasma were significantly decreased by 16.0 and 9.4% due to supplementation with BMA, and by 19.2 and 8.1% with vit. E addition. Plasma phosphorus increased by 19.1% after vit. E+BMA supplementation. In conclusion, use of BMA or vit. E or GT in laying hens diets which grow under heat stress is recommended as it improves production performance and egg quality. © M.A. Al-Harthi, 2014 Licensee PAGE Press, Italy.


Gabal M.A.,King Abdulaziz University
Materials Research Bulletin | Year: 2010

A new process to prepare single-phase nano-sized ferrites, Ni0.8-xCu0.2ZnxFe2O4 with x = 0.1-0.7, was developed using egg-white precursors. TG measurement showed that, the precursors must be calcined at 550 °C. XRD patterns indicated the formation of single-phase cubic ferrites with particle size in the range 28.7-48.4 nm. TEM image gave particle size agrees well with that estimated using XRD. FT-IR spectroscopy showed the characteristic ferrite bands. Hysteresis loops measurements exhibited an increase in the saturation magnetization value (Ms) up to zinc content of 0.2 followed by unexpected decrease, which suggests the preference of Zn2+ ions to occupy octahedral sites. The decrease in the coercivity (Hc) with increasing zinc content is attributed to the lower magneto-crystalline anisotropy of Zn2+ ions compared to Ni2+ ions. Temperature dependence of the molar magnetic susceptibility (χM) suggested a ferrimagnetic behavior of the investigated samples and showed a decrease in the value of the Curie temperature (TC) with increasing zinc. © 2010 Elsevier Ltd. All rights reserved.


Athar H.,King Abdulaziz University
International Journal of Climatology | Year: 2014

Results of a detailed computation of trends in the annual and the seasonal extreme climate indices using the observed daily temperature and precipitation datasets from a total of 19 stations from Saudi Arabia (SA) for the 30-year period (1979-2008) are presented. The temperature based indices have higher value of statistically significant decadal trends and are spatially more widespread as compared to the precipitation based indices. The increase in the frequency of the extreme warm temperatures is larger than the increase in the frequency of the extreme cold temperatures, both on the annual and the seasonal basis. The daily temperature based extremes display more warming in the summer season. The (southwest) coastal stations have displayed more warming as compared to the inland stations. The regional daily temperature range shows a statistically significant increase of 0.21°C decade-1 for SA, during the 30-year period. Warming of extreme maximum temperatures follow the general trend of already noticed warming in SA. © 2013 Royal Meteorological Society.


Hummadi L.A.,King Abdulaziz University
International Journal of Zoological Research | Year: 2012

Chemical mediated nephrotoxicity has been recognized. Para-phenylene Diamine (PPD) a widely used chemical in a variety of industrial products and in almost all hair dye formulation has been tested for its glomerular histopathology after 6 months topical application in two different dosages (0.5 and 1 mg/kg/day) in female Wistar rats. Serum biomarker creatinine and blood urea of kidney injury pointed a significant (p<0.01) increased and decreased Na+ and Cl levels as well as body weights and the mean relative kidney weights were affected by the treatment regard to both the exposure time and the concentration of PPD. Histopathological findings include microscopical damage caused by PPD treatment. Such as glomerular hypertrophy, hyperemia swelling glomerular lining epithelium and mesangial matrix expansion in group III as well as lobulation of glomerular tufts, glomerular cells vacuolation, diffused hyaline and thickening of glomerular basement membrane also seen in group IV. Electron microscopic changes in the group III confirm glomeruli proliferation of the podocytes and mesangial cells, podocytes pedicles fusion and lysis nuclear membrane ruptured, mitochondrial, RER damage. PPD caused various renal corpuscles histological changes in group IV, necrotic of glomerular podocytes, mesangial cells and endothelial cell with detachment accompanied by floppy and vacuolated cytoplasmic extension. Capillaries collapsed and filled with deformed red blood cells (RBCs), neutrophils, macrophages and cellular debris were been observed. Moreover, the podocytes manifested more intensive deterioration than those observed in group III which indicated deformed nucleus and pedicles ruptured, lead to lysis and damage of cytoplasmic organelles. These results highlight the need to reduce exposure to PPD, with particular attention being paid to the known sources of PPD. In addition, public education and strict control over the sale and distribution of PPD should be done to reduce poisoning by this compound. © 2012 Academic Journals Inc.


Akram M.,University of Punjab | Alshehri N.O.,King Abdulaziz University
The Scientific World Journal | Year: 2014

Connectivity has an important role in neural networks, computer network, and clustering. In the design of a network, it is important to analyze connections by the levels. The structural properties of intuitionistic fuzzy graphs provide a tool that allows for the solution of operations research problems. In this paper, we introduce various types of intuitionistic fuzzy bridges, intuitionistic fuzzy cut vertices, intuitionistic fuzzy cycles, and intuitionistic fuzzy trees in intuitionistic fuzzy graphs and investigate some of their interesting properties. Most of these various types are defined in terms of levels. We also describe comparison of these types. © 2014 Muhammad Akram and N. O. Alshehri.


Objective The aim of this study was to investigate the diagnostic criteria and clinical presentations and compare the different treatment modalities in relation to prognosis in a sample of patients with the neuropathic disorder trigeminal neuralgia (TN). Methods A retrospective review study of clinical records was conducted of 92 patients diagnosed with TN. Results The mean age[± standard deviation (SD)] of the patients was 67.3 ± 12.7 years with an average TN duration of 7.1 ± 6 years and a female predominance (M:F = 1:2.5). The maxillary branch was the most involved nerve (in 45% of patients). Twelve patients underwent CT scans, while thirty-six patients had MRIs. Carbamazepine used by 92.4% of patients was the most commonly used drug in the management of the disorder. Twenty-two patients had microvascular decompression (MVD). TN symptoms were completely relieved following surgery in 73% of patients who underwent neurosurgery. Conclusions MRI is highly sensitive in the exclusion of central intracranial lesions and recommended as a routine consideration during the assessment of TN patients. Despite the side effects, carbamazepine is the drug therapy of choice. MVD produces satisfactory relief of TN symptoms in the majority of cases and should be offered to young healthy patients. © 2012 The Gerodontology Society and John Wiley & Sons A/S.


Tjong S.C.,City University of Hong Kong | Tjong S.C.,King Abdulaziz University
Journal of Nanoscience and Nanotechnology | Year: 2014

Graphene with extraordinary high elastic modulus and excellent electrical conductivity has good prospects for use as the filler material for fabricating novel polymer composites designed for electrostatic discharge and EMI shielding protection, field emission, gas sensor, and fuel cell applications. Large amounts of graphene oxide (GO) can be obtained by wet chemical oxidation of graphite into a mixture of concentrated sulfuric acid, sodium nitrate and potassium permanganate. Accordingly, carbon atoms in the basal plane and edges of GO are decorated with oxygenated functional groups, forming an electrical insulator. To restore electrical conductivity, chemical reduction or thermal annealing is needed to eliminate oxygenated groups of GO. However, such treatments induce internal defects and remove oxygenated atoms of GO partially. The remnant-oxygenated groups affect electrical conductivity of graphene greatly. Nevertheless, reduced graphene oxide and thermally reduced graphene oxide are sufficiently conductive to form polymer nanocomposites at very low percolation threshold. This review provides the fundamentals and state-of-the-art developments in the fabrication methods and electrical property characterizations as well as the applications of novel graphene/polymer nanocomposites. Particular attention is paid to their processing- structuralelectrical property relationships. © 2014 American Scientific Publishers.


Salah N.,King Abdulaziz University
International journal of nanomedicine | Year: 2011

Nanoparticles of zinc oxide (ZnO) are increasingly recognized for their utility in biological applications. In this study, the high-energy ball milling (HEBM) technique was used to produce nanoparticles of ZnO from its microcrystalline powder. Four samples were ball milled for 2, 10, 20, and 50 hours, respectively. The structural and optical modifications induced in the 'as synthesized' nanomaterials were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and photoluminescence emission spectra (PL). SEM and TEM results show a gradual decrease in particle size from around 600 to ∼30 nm, with increased milling time. The initial microstructures had random shapes, while the final shape became quite spherical. XRD analysis showed ZnO in a hexagonal structure, broadening in the diffracted peaks and going from larger to smaller particles along with a relaxation in the lattice constant c. The value of c was found to increase from 5.204 to 5.217 Å with a decrease in particle size (600 to ∼30 nm). PL result showed a new band at around 365 nm, whose intensity is found to increase as the particles size decreases. These remarkable structural and optical modifications induced in ZnO nanoparticles might prove useful for various applications. The increase in c value is an important factor for increasing the antibacterial effects of ZnO, suggesting that the HEBM technique is quite suitable for producing these nanoparticles for this purpose.


Koenig H.G.,Duke University | Koenig H.G.,King Abdulaziz University
Journal of Religion and Health | Year: 2012

I address two related questions in this article. First, why conduct research on religion/spirituality (R/S) and health? Second, what are the dangers of misinterpreting or misapplying the results from such research? If relationships are found, so what? What is the practical value or clinical relevance of such information? Why should investigators spend time and scarce financial resources to explore such connections? What might health care professionals do differently as a result? How would people live their lives differently in light of such information? Questions like these need solid answers for the field to continue to move forward. Related to the "So what?" question is the issue of how results from research in this area are translated into popular understanding and application. After discussing why conducting research on religion and health is important, I identify a recently published research report that focuses on the relationship between R/S and self-control, an article that received considerable media press coverage. I present the results reported by the authors of this study and then examine a column written about the study that appeared in the New York Times. Finally, I explore what the findings mean, how the media portrayed the findings, and problems that might result depending on how people applied those findings. © 2012 Springer Science+Business Media, LLC.


Alhazmy M.M.,King Abdulaziz University
Energy | Year: 2011

Improving the performance of Multi Stage Flash (MSF) desalination plants is a major objective in the seawater desalination industry. Fresh water production rates from MSF plants depend on the evaporation range defined as the difference between the top brine temperature (TBT) and the bottom stage temperature. Lowering the temperature of the plant bottom stage elongates the evaporation range and increases the yield. A modified multi stage flash plant with brine mixing and cooling (MSF-MC) is presented in this paper. Part of the brine leaving the plant is mixed with fresh seawater feed then cooled to low temperature before it enters the bottom stage feed heater. This MSF-MC features several advantages such as expanded evaporation range at the conventional TBT levels, reduced feed pumping power, moderate levels of chemical treatment requirements and fixed fresh water production rates independent of seasonal seawater conditions. Operating with low feed mass fraction minimizes the cooling load and reduces the cooler size. An improvement in the yield by 1.18%-1.4% for every 1 °C reduction in the plant bottom temperature can be achieved with MSF-MC compared to conventional MSF systems. © 2011 Elsevier Ltd.


Li H.,Bohai University | Gao H.,Harbin Institute of Technology | Gao H.,King Abdulaziz University | Shi P.,University of Adelaide | And 2 more authors.
Automatica | Year: 2014

This paper is concerned with the stabilization problem for a class of Markovian stochastic jump systems against sensor fault, actuator fault and input disturbances simultaneously. In the proposed approach, the original plant is first augmented into a new descriptor system, where the state vector, disturbance vector and fault vector are assembled into the state vector of the new system. Then, a novel augmented sliding mode observer is presented for the augmented system and is utilized to eliminate the effects of sensor faults and disturbances. An observer-based mode-dependent control scheme is developed to stabilize the resulting overall closed-loop jump system. A practical example is given to illustrate the effectiveness of the proposed design methodology. © 2014 Elsevier Ltd. All rights reserved.


Abolfazli S.,University of Malaya | Sanaei Z.,University of Malaya | Ahmed E.,University of Malaya | Gani A.,University of Malaya | And 3 more authors.
IEEE Communications Surveys and Tutorials | Year: 2014

Recently, Cloud-based Mobile Augmentation (CMA) approaches have gained remarkable ground from academia and industry. CMA is the state-of-the-art mobile augmentation model that employs resource-rich clouds to increase, enhance, and optimize computing capabilities of mobile devices aiming at execution of resource-intensive mobile applications. Augmented mobile devices envision to perform extensive computations and to store big data beyond their intrinsic capabilities with least footprint and vulnerability. Researchers utilize varied cloud-based computing resources (e.g., distant clouds and nearby mobile nodes) to meet various computing requirements of mobile users. However, employing cloud-based computing resources is not a straightforward panacea. Comprehending critical factors (e.g., current state of mobile client and remote resources) that impact on augmentation process and optimum selection of cloud-based resource types are some challenges that hinder CMA adaptability. This paper comprehensively surveys the mobile augmentation domain and presents taxonomy of CMA approaches. The objectives of this study is to highlight the effects of remote resources on the quality and reliability of augmentation processes and discuss the challenges and opportunities of employing varied cloud-based resources in augmenting mobile devices. We present augmentation definition, motivation, and taxonomy of augmentation types, including traditional and cloud-based. We critically analyze the state-of-the-art CMA approaches and classify them into four groups of distant fixed, proximate fixed, proximate mobile, and hybrid to present a taxonomy. Vital decision making and performance limitation factors that influence on the adoption of CMA approaches are introduced and an exemplary decision making flowchart for future CMA approaches are presented. Impacts of CMA approaches on mobile computing is discussed and open challenges are presented as the future research directions. © 2014 IEEE.


Joye I.J.,University of Massachusetts Amherst | Joye I.J.,Catholic University of Leuven | McClements D.J.,University of Massachusetts Amherst | McClements D.J.,King Abdulaziz University
Current Opinion in Colloid and Interface Science | Year: 2014

Tailor-made microparticles and nanoparticles are finding increasing use in food products to alter their nutritional characteristics, flavor profile, appearance, rheology, stability, and processability. These particles are often fabricated from food-grade biopolymers, such as proteins and polysaccharides. Food biopolymers display a diverse range of molecular and physicochemical properties (e.g. molecular weight, charge, branching, flexibility, polarity, and solubility) which enables the assembly of colloidal particles that exhibit a broad range of functional attributes. By careful selection of appropriate biopolymers and assembly methods, biopolymer particles can be fabricated with tailored behaviors or features. In this article, we review recent developments in the design and fabrication of functional biopolymer nanoparticles and microparticles, and highlight some of the challenges that will be the focus of future research. © 2014 Elsevier Ltd.


Van Ijzendoorn M.H.,Leiden University | Belsky J.,King Abdulaziz University | Bakermans-Kranenburg M.J.,Leiden University
Translational Psychiatry | Year: 2012

We present results of a meta-analysis of gene-by-environment (G × E) studies involving the serotonin transporter genotype 5HTTLPR to evaluate empirical support for two competing conceptual frameworks in developmental psychopathology: diathesis-stress and differential susceptibility. From a diathesis-stress perspective, the cumulative negative effects of the short allele (ss and sl genotypes) and adverse environments on development have been stressed. From a differential-susceptibility perspective, carriers of the s allele are predicted to be more open to adverse as well as positive environments, for better and for worse. Studies with children and adolescents up to 18 years of age (N=9361) were included. We found 41 effect sizes (N=5863) for the association between negative environments and developmental outcomes with or without significant moderation by 5HTTLPR genotype and 36 effect sizes (N=3498) for the potentially 5HTTLPR-moderated association between positive environments and developmental outcomes. Five moderators were examined: age, ethnicity, genotyping (biallelic or triallelic) and methods used to assess environment and outcome. In the total set of studies, including studies with mixed ethnicities, we found that ss/sl carriers were significantly more vulnerable to negative environments than ll carriers, thus supporting the diathesis-stress model. In the Caucasian samples, however, ss/sl carriers also profited significantly more from positive environmental input than ll carriers. Associations between (positive or negative) environment and (positive or negative) developmental outcome were absent for ll carriers. The meta-analytic findings support the hypothesis that in Caucasian samples 5HTTLPR is a genetic marker of differential susceptibility. G × E interactions might be critically dependent on ethnicity. © 2012 Macmillan Publishers Limited All rights reserved.


Xie Y.-P.,Chinese University of Hong Kong | Mak T.C.W.,Chinese University of Hong Kong | Mak T.C.W.,King Abdulaziz University
Chemical Communications | Year: 2012

In the giant mixed-metal silver(i)-ethynide cluster compound [Bz(Et) 3N +] 8[(Et) 4N +] 2[(V 2O 7) 2@Ag 44(CC tBu) 14at(V 32O 96)], the cyclic polyoxovanadate {V 32O 96} located at a 4 site takes a contorted configuration to wrap around an inner Ag 44 cluster that in turn encapsulates a pair of pyrovanadate templates. © The Royal Society of Chemistry 2012.


Aldosari B.,King Abdulaziz University
International Journal of Medical Informatics | Year: 2014

Objective: Outside a small number of OECD countries, little information exists regarding the rates, levels, and determinants of hospital electronic health record (EHR) system adoption. This study examines EHR system adoption in Riyadh, Saudi Arabia. Materials and methods: Respondents from 22 hospitals were surveyed regarding the implementation, maintenance, and improvement phases of EHR system adoption. Thirty-seven items were graded on a three-point scale of preparedness/completion. Measured determinants included hospital size, level of care, ownership, and EHR system development team composition. Results: Eleven of the hospitals had implemented fully functioning EHR systems, eight had systems in progress, and three had not adopted a system. Sixteen different systems were being used across the 19 adopting hospitals. Differential adoption levels were positively related to hospital size and negatively to the level of care (secondary versus tertiary). Hospital ownership (nonprofit versus private) and development team composition showed mixed effects depending on the particular adoption phase being considered. Discussion: Adoption rates compare favourably with those reported from other countries and other districts in Saudi Arabia, but wide variations exist among hospitals in the levels of adoption of individual items. General weaknesses in the implementation phase concern the legacy of paper data systems, including document scanning and data conversion; in the maintenance phase concern updating/maintaining software; and in the improvement phase concern the communication and exchange of health information. Conclusion: This study is the first to investigate the level and determinants of EHR system adoption for public, other nonprofit, and private hospitals in Saudi Arabia. Wide interhospital variations in adoption bear implications for policy-making and funding intervention. Identified areas of weakness require action to increase the degree of adoption and usefulness of EHR systems. © 2014 Elsevier Ireland Ltd.


Bukhari A.A.,King Abdulaziz University
Clinical Ophthalmology | Year: 2013

Purpose: We aimed to compare the outcomes of primary external dacryocystorhinostomy and silicone tube with anterior and posterior mucosal flap anastomosis, versus dacryocystorhinostomy and silicone intubation with anterior mucosal flap anastomosis. Methods: We utilized the electronic databases PubMed, EMBASE, Ovid, Cochrane Central Register of Controlled Trials, and MEDLINE® to find articles related to external dacryocystorhinostomy. For inclusion in this meta-analysis, we isolated prospective and retrospective comparative studies of adult patients with acquired nasolacrimal duct obstruction, or chronic dacryocystitis, who had undergone primary external dacryocystorhinostomy and silicone intubation with anterior and posterior flap anastomosis; versus primary dacryocystorhinostomy and silicone intubation with anterior flap anastomosis. The minimum follow-up period for each study was 4 months. Results: We identified and analyzed seven studies. Overall, dacryocystorhinostomy with anterior and posterior flap anastomosis was performed on 368 eyes, while primary external dacryocystorhinostomy with anterior flap anastomosis was performed on 397 eyes. There was no significant difference in the success rates of both techniques (risk ratio: 0.987; 95% confidence interval 0.946-1.030). Conclusion: For patients with acquired nasolacrimal duct obstruction or chronic dacryocystitis, there was no significant difference in the resolution of epiphora, and patency of the lacrimal system, between those who underwent external dacryocystorhinostomy with anterior and posterior mucosal flap anastomosis, and those who had dacryocystorhinostomy with anterior flap anastomosis. © 2013 Bukhari.


Al-Zahrani M.S.,King Fahad Military Hospital | AlGhamdi H.S.,King Abdulaziz University
Saudi Medical Journal | Year: 2012

Objectives: To investigate the effect of conventional periodontal therapy on serum C-reactive protein (CRP) level and periodontal status in obese and normal-weight chronic periodontitis patients. Methods: This is a controlled clinical trial conducted at the King Abdulaziz University Faculty of Dentistry, Jeddah, Kingdom of Saudi Arabia between December 2009 and March 2011. A total of 40 women affected with moderate to severe chronic periodontitis were selected (20 obese [test group] and 20 normal-weight [control]). Smokers, pregnant women, and subjects with any systemic disease were excluded. Serum CRP level and periodontal parameters, including clinical attachment level, probing depth, bleeding on probing and plaque scores were assessed at baseline, and 2 months after non-surgical periodontal treatment. Results: Periodontal therapy was effective in reducing gingival inflammation, as well as serum CRP level in the total sample and within each group. The pre- treatment mean level of serum CRP was 0.78 (±0.51) and post- treatment was 0.55 (±0.41) mg/l in the total sample (p=0.001). A tendency was observed toward a better systemic response to treatment in normal- weight compared to obese women, however, it was not statistically significant (the mean changes in CRP levels after therapy were 0.28 [±0.43] and 0.19 [±0.32] mg/l). Conclusion: Periodontal treatment is effective in reducing systemic inflammation as measured by serum CRP level, and obesity does not have a major negative impact on response to periodontal therapy.


Othman R.,King Abdulaziz University
International Journal of Impact Engineering | Year: 2014

All-polymeric Hopkinson-Kolsky bars technique was already proposed to test soft materials at intermediate and high strain rates. In this work, the accuracy of this technique, to measure forces or stresses, is investigated. Namely, the elastic processing, which is typically used for conventional bars, is compared to the viscoelastic processing that is more appropriate for polymer materials. This is motivated by the lack of details on the processing method used in the literature. While studying, aluminium honeycomb, lead, polyurea and polypropylene foams, it was demonstrated that the elastic processing can lead to significant errors mainly at small strains and high strain rates. This study emphasises the importance of using an appropriate stiffness modulus for polymeric Kolsky-Hopkinson bars. © 2014 Elsevier Ltd. All rights reserved.


Lucero M.J.,Rice University | Henderson T.M.,Rice University | Scuseria G.E.,Rice University | Scuseria G.E.,King Abdulaziz University
Journal of Physics Condensed Matter | Year: 2012

We show that the middle-range exchangecorrelation hybrid of Henderson, Izmaylov, Scuseria and Savin (HISS) performs extremely well for elemental and binary semiconductors with narrow or visible spectrum band gaps, as well as some wider gap or more ionic systems used in devices. The lattice parameters are superior to those predicted by the screened hybrid functional of Heyd, Scuseria and Ernzerhof (HSE), and provide a significant improvement over the geometries predicted by typical semilocal functionals, yielding results competitive with PBEsol, which was specially tuned for solids. HISS also yields band gaps superior to those produced by functionals developed specifically for the solid state. Timings indicate that HISS is more computationally efficient than HSE, implying that the high quality lattice constants coupled with improved optical band gap predictions render HISS a useful adjunct to HSE in the modeling of geometry-sensitive semiconductors. © 2012 IOP Publishing Ltd.


Al-Hazmi N.A.,King Abdulaziz University
African Journal of Biotechnology | Year: 2010

The fact that toxic species do not always produce toxins and that other species not known to produce toxins were found to be toxic in some environments have been previously reported. However, different fungal species behave unexpectedly in different ecosystems. That is why the main objective of this work was to detect the toxicity of some fungal species existing in some environmentally important ecosystem in Jeddah in order to find a correlation between some of these environmental factors and the detected toxicity. The aim is to use some of the isolated non toxic strains that are capable of acting upon some environmental pollutant as a bioremediation approach. Forty nine fungal isolates were isolated from six different sources and ecosystems in both terrestrial and marine environment (agricultural soil, wheat grain, sewage dump, oily sewage dump, soil around car oil dump and marine fauna). Aflatoxins were detected in 18.4% of the total isolates. All the isolates from marine environment were non toxic to brine shrimp. © 2010 Academic Journals.


Warshauer D.H.,University of North Texas Health Science Center | King J.L.,University of North Texas Health Science Center | Budowle B.,University of North Texas Health Science Center | Budowle B.,King Abdulaziz University
Forensic Science International: Genetics | Year: 2015

STRait Razor (the STR Allele Identification Tool-Razor) was developed as a bioinformatic software tool to detect short tandem repeat (STR) alleles in massively parallel sequencing (MPS) raw data. The method of detection used by STRait Razor allows it to make reliable allele calls for all STR types in a manner that is similar to that of capillary electrophoresis. STRait Razor v2.0 incorporates several new features and improvements upon the original software, such as a larger default locus configuration file that increases the number of detectable loci (now including X-chromosome STRs and Amelogenin), an enhanced custom locus list generator, a novel output sorting method that highlights unique sequences for intra-repeat variation detection, and a genotyping tool that emulates traditional electropherogram data. Users also now have the option to choose whether the program detects autosomal, X-chromosome, Y-chromosome, or all STRs. Concordance testing was performed, and allele calls produced by STRait Razor v2.0 were completely consistent with those made by the original software. © 2014 Elsevier Ireland Ltd.


Al-Malki A.L.,King Abdulaziz University
Toxicology and Industrial Health | Year: 2014

Cyclophosphamide (CP) is an alkylating agent that has been considered effective for cancer treatment. Lycopene, the pigment in tomato fruits, has beneficial effect in the treatment of some diseases. The goal of this study is to evaluate the protective effect of lycopene alone or combined with melatonin (Mel) in inhibiting the oxidative stress and toxic effect of CP in rats. Five groups of rats were included in this study; Group I served as the control. Rats in groups II-V were administrated with single dose of CP (150 mg/kg B.W) interperitoneally for 3 days. On the same day of CP administration, the rats in group III were fed a diet supplemented with lycopene (50 mg/kg of diet), rats in group IV were administered with a dose of 2.5 mg Mel/kg body weight (bw) injected subcutaneously and rats in group V were supplemented with lycopene and a dose of 2.5 mg Mel/kg bw injected subcutaneously. After 15 days the blood samples were collected. Results obtained showed that CP exerted its toxic effect by increasing the free radicals and reactive oxygen species that causes lipid peroxidation and cell damage, and this in turn is detected by elevation in nitric oxide (NO) and malondialdehyde (MDA), while the activities of antioxidants enzymes including (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) were significantly decreased as compared with the control rats. The combined treatment (Lyco + Mel) group showed potential reduction in these parameters more than those treated with lyco alone. The activities of SOD, CAT and GPx were found significantly high than lyco alone treated rats. A positive significant correlation between NO and MDA (r =.81). In conclusion, these results suggested that supplementation of diet with lycopene and Mel provided antioxidant defense with strong chemopreventive activity against Cp-induced cytotoxicity. © The Author(s) 2012.


Dhakshinamoorthy A.,Madurai Kamaraj University | Garcia H.,Polytechnic University of Valencia | Garcia H.,King Abdulaziz University
Chemical Society Reviews | Year: 2014

Metal-organic frameworks (MOFs) are finding increasing application as solid catalysts for liquid phase reactions leading to the synthesis of fine chemicals. In the present review we have focused on those reports describing the use of MOFs as catalysts for the synthesis of N-containing heterocycles that is a class of organic compounds with high added value due to their therapeutic use as drugs and their remarkable biological activities. After an introduction describing relevant structural features of MOFs and the nature of their active sites, this manuscript is organized according to the type of N-containing heterocycle synthesized employing MOFs as catalysts including pyrimidines, N-substituted piperidines, quinolines, indoles, N-substituted imidazoles, triazoles and heterocyclic amides. Special attention has been paid to the structural stability of MOFs under the reaction conditions, to the occurrence of metal leaching and reusability. The final section of this review provides some concluding remarks and future prospects for the field, with emphasis on showing the superiority of MOFs with respect to other solid catalysts for this type of liquid phase organic reactions and pointing out that the final goal in this research would be the use of these materials as catalysts in real industrial synthesis. This journal is © the Partner Organisations 2014.


Objectives: To evaluate the safety, ovarian function preservation, reproductive ability, and the emotional attitude after a conservative surgery for ovarian cancer. Methods: This is a retrospective study of women conservatively treated for primary ovarian cancer between January 2000 and December 2010 at King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia. Patient's charts were reviewed for pathology, stage, requirement of adjuvant chemotherapy, and recurrent, as well as menstrual history, and pregnancy after treatment. During follow up the patients were asked 3 questions about their emotional attitude toward their disease. Results: There were 39 patients identified (mean age 22 years). Thirty-one (80%) patients were presented with stage I and 20 (52%) were Germ cell tumor. Fifteen (39%) patients received initial chemotherapy after primary surgery. Three (8%) patients had recurrent. Thirty-eight (98%) patients retuned to a regular menstruation after treatment. Eight patients (20%) had a normal pregnancy. Of the respondents to the given questions, 10 (44%) patients claimed that their disease did not have any impact on their desire to have children and 12 patients (52%) feared that their ovarian disease could have damage in their reproductive potential. Only 9 patients (39%) had no concerned about the effect of the treatment they received on the offspring. Conclusion: Fertility sparing surgery in ovarian cancer appears to be safe, and a practical treatment option in selected cases with ovarian cancer diagnosis. Most patients can have ovarian preservation after treatment and should not be discouraged from getting pregnant.


Panda S.S.,University of Florida | Hall C.D.,University of Florida | Oliferenko A.A.,University of Florida | Katritzky A.R.,University of Florida | Katritzky A.R.,King Abdulaziz University
Accounts of Chemical Research | Year: 2014

Peptides are ubiquitous in nature where they play crucial roles as catalysts (enzymes), cell membrane ion transporters, and structural elements (proteins) within biological systems. In addition, both linear and cyclic peptides have found use as pharmaceuticals and components of various conjugate molecular systems. Small wonder then that chemists throughout the ages have sought to mimic nature by synthesis of the amide polymers known as peptides and proteins.The fundamental reaction in the formation of a peptide bond is condensation of an amine of one amino acid with the activated carbonyl group of another. This "fragment condensation" has been achieved in many ways both in solution and by solid-phase peptide synthesis (SPSS) on resin. The most successful method for in-solution coupling is known as native chemical ligation (NCL), and the technique dates back to the pioneering work of Wieland (1953) and subsequently Kent (1994) among many others. This Account builds on the established principles of NCL as applied specifically to S-, O-, and N-isopeptides, molecules that are generally more soluble and less prone to aggregation than native peptides.This Account also covers NCL of isopeptides containing terminal and nonterminal S-acylated cysteine units, reactions that enable the synthesis of native peptides from S-acyl peptides without the use of auxiliaries. With C-terminal S-acyl isopeptides, NCL was carried out under microwave irradiation in phosphate buffer (pH 7.3) at 50°C. Intramolecular acyl migration was observed through 5-19-membered transition states with relative rates, as assessed by product analysis, in the order, 5 > 10 > 11 > 14, 16, or 17 > 12 > 13, 15, or 19 > 18 ≫ 9 > 8. The rate/pH profile for the 15-membered TS showed a maximum for ligated product versus transacylation at pH 7.0-7.3 presumably associated with the pK a of the N-nucleophile in the hydrogen-bonded TS. Cysteine occurs at low abundance (1.7%) in natural peptides and is rarely available in a terminal position thus limiting the utility of the method. This Account reports, however, NCL at nonterminal acyl cysteine through 5-, 8-, 11-, and 14-membered TSs with relative rates of ligation in the order, 5 ≫ 14 > 11 ≫ 8, thus paralleling the results with acylated terminal cysteine residues.In an obvious sequel to the work with acylated cysteine, we discuss intramolecular O- to N-acyl shift in O-acyl serine and O-acyl tyrosine isopeptides where the story becomes more complex in terms of viable conditions and optimum size of the cyclic TS. N- to N-acyl migration in acyl tryptophan isopeptides is described, and finally, chemical ligation is applied to the synthesis of cyclic peptides. Conformational analysis and quantum chemical calculations are used to rationalize ligation through a range of cyclic transition states.This Account highlights the fact that NCL of acyl isopeptides is an extremely useful strategy for the synthesis of a wide variety of native peptides in good yields and under mild conditions. Mechanistic aspects of the ligations are not fully resolved, but theoretical studies indicate that hydrogen bonding within the various cyclic transition states plays a major role. © 2014 American Chemical Society.


Meng F.,Boyce Thompson Institute for Plant Research | Altier C.,Cornell University | Martin G.B.,Boyce Thompson Institute for Plant Research | Martin G.B.,Cornell University | Martin G.B.,King Abdulaziz University
Environmental Microbiology | Year: 2013

Despite increasing incidences of human salmonellosis caused by consumption of contaminated vegetables, relatively little is known about how the plant immune system responds to and may inhibit Salmonella colonization. Here we show that SalmonellaTyphimurium activates the plant immune system primarily due to its recognition of the flg22 region in Salmonella flagellin. Several previously identified plant genes that play a role in immunity were found to affect the host response to Salmonella. The Salmonella flg22 (Seflg22) peptide induced the immune response in leaves which effectively restricted the growth of Salmonella as well as the plant pathogenic bacterium, Pseudomonas syringae pv. tomato. Induction of immune responses by Seflg22 was dependent on the plant FLS2 receptor. Salmonella multiplied poorly on plant tissues similar to other bacteria which are non-pathogenic to plants. However, Salmonella populations increased significantly when co-inoculated with P.syringae pv. tomato but not when co-inoculated with a type III secretion system mutant of this pathogen. Our results suggest that Salmonella benefits from the immune-suppressing effects of plant pathogenic bacteria, and this growth enhancement may increase the risk of salmonellosis. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.


Abdel Salam M.,King Abdulaziz University
International Journal of Environmental Science and Technology | Year: 2013

Multi-walled carbon nanotubes were used successfully for the removal of Copper(II), Lead(II), Cadmium(II), and Zinc(II) from aqueous solution. The results showed that the % adsorption increased by raising the solution temperature due to the endothermic nature of the adsorption process. The kinetics of Cadmium(II), Lead(II), Copper(II), and Zinc(II) adsorption on Multi-walled carbon nanotubes were analyzed using the fraction power function model, Lagergren pseudo-first-order, pseudo-second-order, and Elovich models, and the results showed that the adsorption of heavy metal ions was a pseudo-second-order process, and the adsorption capacity increased with increasing solution temperature. The binding of the metal ions by the carbon nanotubes was evaluated from the adsorption capacities and was found to follow the following order: Copper(II) > Lead(II) > Zinc(II) > Cadmium(II). The thermodynamics parameters were calculated, and the results showed that the values of the free energies were negative for all metals ions, which indicated the spontaneity of the adsorption process, and this spontaneity increased by raising the solution temperature. The change in entropy values were positives, indicating the increase in randomness due to the physical adsorption of heavy metal ions from the aqueous solution to the carbon nanotubes' surface. Although the enthalpy values were positive for all metal ions, the free energies were negative, and the adsorption was spontaneous, which indicates that the heavy metal adsorption of Multi-walled carbon nanotubes was an entropy-driving process. © 2012 CEERS, IAU.


Armstrong L.,Northumbria University | Al-Aama J.,King Abdulaziz University | Stojkovic M.,University of Kragujevac | Lako M.,Northumbria University
Stem Cells | Year: 2014

Although certainly one of the most recognizable characteristics of human biology, aging remains one of the least understood. This is largely attributable to the fact that aging is both gradual and inherently complex, with almost all aspects of physiology and phenotype undergoing steady modification with advancing age. The complexity of the aging process does not allow for a single all-encompassing definition, yet decades of study using diverse systems, methodologies, and model organisms have begun to build a consensus regarding the central physiological characteristics of aging. Indeed, such studies have shown that the process of aging is invariably accompanied by a diminished capacity to adequately maintain tissue homeostasis or to repair tissues after injury. When homeostatic control diminishes to the point at which tissue/organ integrity and function are no longer sufficiently maintained, physiologic decline ensues, and aging is manifested. Inadequate organ homeostasis indicates possible dysfunction of tissue-specific stem cells. Several mechanisms have been postulated to account for age-related cellular changes; however, increasing literature evidence suggests that age-related changes to the epigenome make a major contribution to the aged phenotype. In this review, we discuss the evidence for epigenetic contributions to tissue-specific stem cell ageing. Stem Cells 2014;32:2291-2298 © 2014 AlphaMed Press.


AlZahrani A.Z.,King Abdulaziz University | Srivastava G.P.,University of Exeter
Applied Surface Science | Year: 2010

The atomic and electronic structures of graphane (hydrogen-passivated graphene) are theoretically investigated using the local density approximation (LDA) of the density functional theory (DFT) and the pseudopotential method. Our total energy calculations suggest that the chairlike configuration for graphane is more energetically stable than the boatlike and tablelike configurations by approximately 0.129 eV/cell and 0.655 eV/cell, respectively. Our calculations suggest that the LDA band gap of the chairlike structure is approximately 3.9 eV. The equilibrium geometry and the band structure of the chairlike conformer are investigated and compared with the available experimental and theoretical data. We further present total and partial charge density to reveal the orbital nature of the highest occupied and the lowest unoccupied states. © 2010 Elsevier B.V. All rights reserved.


Yu J.,Wuhan University of Technology | Yu J.,King Abdulaziz University | Wang K.,Wuhan University of Technology | Xiao W.,Wuhan University | Cheng B.,Wuhan University of Technology
Physical Chemistry Chemical Physics | Year: 2014

Photocatalytic reduction of CO2 into renewable hydrocarbon fuels is an alternative way to develop reproducible energy, which is also a promising way to solve the problem of the greenhouse effect. In this work, graphitic carbon nitride (g-C3N4) was synthesized by directly heating thiourea at 550 °C and then a certain amount of Pt was deposited on it to form g-C3N4-Pt nanocomposites used as catalysts for photocatalytic reduction of CO2 under simulated solar irradiation. The main products of photocatalysis were CH4, CH3OH and HCHO. The deposited Pt acted as an effective cocatalyst, which not only influenced the selectivity of the product generation, but also affected the activity of the reaction. The yield of CH4 first increased upon increasing the amount of Pt deposited on the g-C3N4 from 0 to 1 wt%, then decreased at 2 wt% Pt loading. The production rates of CH 3OH and HCHO also increased with the content of Pt increasing from 0 to 0.75 wt% and the maximum yield was observed at 0.75 wt%. The Pt nanoparticles (NPs) could facilitate the transfer and enrichment of photogenerated electrons from g-C3N4 to its surface for photocatalytic reduction of CO2. At the same time, Pt was also used a catalyst to promote the oxidation of products. The transient photocurrent response further confirmed the proposed photocatalytic reduction mechanism of CO2. This work indicates that the deposition of Pt is a good strategy to improve the photoactivity and selectivity of g-C3N4 for CO2 reduction. © 2014 the Partner Organisations.


Navalon S.,Polytechnic University of Valencia | Dhakshinamoorthy A.,Madurai Kamaraj University | Alvaro M.,Polytechnic University of Valencia | Garcia H.,Polytechnic University of Valencia | Garcia H.,King Abdulaziz University
Chemical Reviews | Year: 2014

Carbons with large surface area such as active carbons and carbon black powders have since ever been considered as supports to deposit transition metals that were the relevant catalytic centers. In this type of materials the role of carbon is to disperse the metal on a very large surface area and maybe in the best case also adsorb reactants near the metal particles. In the case of carbocatalysts the key point is to incorporate the active sites into the carbon by suitable modifications, making metals unnecessary. The main purpose of the present review is to show the advantages and possibilities that G-mat offer in catalysis due to their 2D morphology and to the possibility of introducing heteroatoms and functional groups on the G sheet in such a way that they can act as catalytic center. Nevertheless, CVD techniques require specialized equipment and are still not routine in most of catalytic laboratories.


Chen Z.,Tsinghua University | Wang X.,Columbia University | Wang X.,King Abdulaziz University | Zhang X.,Tsinghua University
IEEE Journal on Selected Areas in Communications | Year: 2013

We propose continuous power allocation strategies for secondary users (SUs) based on sensing the primary user (PU) channels in a multiband cognitive radio (CR) network. Unlike the conventional sensing-based spectrum sharing, where there are two transmit power levels corresponding to whether the PU is sensed present or not, in the proposed strategy, the power levels are continuous functions of the sensing statistics, and optimized with respect to the achievable rate of the SU. The continuous power allocation function is parameterized by some channel parameters of the PU and SU, and we treat the cases of perfect and quantized channel state information (CSI) separately, where the former provides an upper bound on the achievable rate with full channel information; and the latter constitutes an efficient practical power allocation method for the SU with statistic/partial channel information. The power control process consists of two phases: in the first phase, the SU listens to the multiple bands licensed to the PU and obtains the sensing statistics, e.g., the received signal energies on these bands; in the second phase, the SU adjusts its transmit power levels on these bands based on the sensing results. Optimal power allocation schemes are derived to maximize the achievable rate at the SU under several possible combinations of the peak/average transmit power constraints at the SU and the peak/average interference power constraints at the PU. Simulation results demonstrate that the proposed strategies can significantly improve the achievable throughput of the SU compared to the conventional methods. © 1983-2012 IEEE.


Mubarak A.A.,King Abdulaziz University
Surface Review and Letters | Year: 2013

This study presents an ab initio investigation of the interaction of Al5H12 with the alloying transition elements (TM) in the TMAl5H12 (TM = Ti, V, Fe, Co and Ni). Hydrogen atoms are found to prefer the tetrahedral sites in the fcc Al bulk system with a binding energy that is more energetically favored than octahedral sites by 0.17 eV. Absorbed H atoms in Al increase the lattice constant and decrease the cohesive energy by 13.8% and 32.7%, respectively. The present values of the H-H bond length (0.75 Å) and the dissociation energy of H2 (4.47 eV) are in good agreement with the previously measured values. The binding energy of H atoms in TiAl5H12 system is higher than the other studied systems due to the hybridization between s-state of H and d-state of Ti atom. The magnetic moments of Fe in FeAl5H12 system and Ni in NiAl5H12 system are enhanced as compared to the dehydrogenated system. © 2013 World Scientific Publishing Company.


Thai C.H.,Ton Duc Thang University | Ferreira A.J.M.,University of Porto | Ferreira A.J.M.,King Abdulaziz University | Carrera E.,Polytechnic University of Turin | Nguyen-Xuan H.,Ton Duc Thang University
Composite Structures | Year: 2013

We present an isogeometric finite element formulation for static, free vibration and buckling analysis of laminated composite and sandwich plates. The idea behind this work is to associate an isogeometric analysis (IGA) with a layerwise theory [. A.J.M. Ferreira. Analyis of composite plates using a layerwise deformation theory and multiquadrics discretization. Mech Adv Mater Struct 2005;12(2):99-112]. Isogeometric analysis based on non-uniform rational B-spline (NURBS) basic functions were recently proposed to preserve exact geometries and to enhance very significantly the accuracy of the traditional finite elements. B-splines basic function (or NURBS) is used to represent for both geometric and field variable approximations, which provide a flexible way to make refinement and degree elevation. They enable us to achieve easily the smoothness with arbitrary continuity order compared with the traditional FEM. The layerwise theory assumes a first-order shear deformation theory in each layer and the imposition of displacement continuity at the layers interfaces. This permits to remove shear correction factors and improves the accuracy of transverse shear stresses. Intensive numerical studies have been conducted to show the highly efficient performance of the proposed formulation. © 2013 Elsevier Ltd.


Almazroui M.,King Abdulaziz University
Atmospheric Research | Year: 2011

The short-term rainfall climatology regime over Saudi Arabia is obtained from the Tropical Rainfall Measuring Mission (TRMM) data for the period 1998-2009. The TRMM rainfall amounts are calibrated with respect to the rain-gauge data recorded at 29 stations across the country. Day-to-day rainfall comparisons show that the TRMM rainfall trends are very similar to the observed data trends, even if a general overestimation in the satellite products must be highlighted. Besides, especially during the wet season, some of the TRMM algorithm runs tend to underestimate the retrieved rainfalls. The TRMM rainfall data also closely follow the observed annual cycle on a monthly scale. The correlation coefficient for rainfall between the TRMM and the rain-gauge data is about 0.90, with a 99% level of significance on the monthly scale.The spatio-temporal distributions of rainfall over Saudi Arabia are analyzed. Besides the four conventional seasons, this analysis consider the wet (November-April) and dry (June-September) seasons, based on the rainfall amounts recorded. Spring is the highest and winter is the second highest rainfall-occurring season, resulting in large amounts of rainfall during the wet season over most of the country. Regional variations in the rainfall climatology over Saudi Arabia are studied through defining four regions. The false alarm ratio, probability of detection, threat score, and skill score are calculated to evaluate the TRMM performance. The country's average annual rainfall measured by the TRMM is 89.42. mm, whereas the observed data is 82.29. mm. Thus, the rainfall in Saudi Arabia is suggested as being the TRMM value multiplied by 0.93 plus 0.04. After this calibration, the TRMM-measured rainfall is almost 100% of the observed data, thereby confirming that TRMM data may be used in a variety of water-related applications in Saudi Arabia. © 2010 Elsevier B.V.


Hochberg Z.,Meyer Childrens Hospital | Hochberg Z.,Technion - Israel Institute of Technology | Belsky J.,University of California at Davis | Belsky J.,King Abdulaziz University | Belsky J.,Birkbeck, University of London
BMC Medicine | Year: 2013

Despite substantial heritability in pubertal development, much variation remains to be explained, leaving room for the influence of environmental factors to adjust its phenotypic trajectory in the service of fitness goals. Utilizing evolutionary development biology (evo-devo), we examine adolescence as an evolutionary life-history stage in its developmental context. We show that the transition from the preceding stage of juvenility entails adaptive plasticity in response to energy resources, other environmental cues, social needs of adolescence and maturation toward youth and adulthood. Using the evolutionary theory of socialization, we show that familial psychosocial stress fosters a fast life history and reproductive strategy rather than early maturation being just a risk factor for aggression and delinquency. Here we explore implications of an evolutionary-developmental-endocrinological-anthropological framework for theory building, while illuminating new directions for research. © 2013 Hochberg and Belsky; licensee BioMed Central Ltd.


Hao N.,CAS Institute of Physics | Hao N.,Purdue University | Hu J.,CAS Institute of Physics | Hu J.,Purdue University | Hu J.,King Abdulaziz University
Physical Review X | Year: 2014

A distinct electronic structure was observed in the single-layer FeSe which shows surprisingly high-temperature superconductivity over 65 K. Here, we demonstrate that the electronic structure can be explained by the effective strain effect due to substrates. More importantly, we find that this electronic structure can be tuned into robust topological phases from a topologically trivial metallic phase by the spinorbital interaction and couplings to substrates. The topological phase is robust against any perturbations that preserve the time-reversal symmetry. Our study suggests that nontrivial topology and high-Tc superconductivity can be intertwined in the single FeSe layer to search novel physics.


A Regional Climate Model (RCM) is employed to simulate and understand the life cycle of the two systems that produced heavy rainfall spells over western Saudi Arabia in November 1996. The first spell of heavy rain occurred from 13 to 20 November, whereas the second occurred from 25 to 27 November 1996. Their spatial patterns are compared with rain-gauge data and also with the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) and the Global Precipitation Climatology Project (GPCP) gridded observations. A series of 144 experiments are conducted for different domain sizes and resolution as well as different boundary forcings and convective parameterization schemes to investigate the optimum combination for the simulation of the two spells. The RCM simulates well the development, the propagation and the life cycle of the first spell (8-day long) as well as the second spell (3-day long) during November 1996. In particular, the simulation demonstrates how the two systems developed, merged with new cells, reached to maturity, and then decayed, as they moved eastward across the Red Sea, producing rain in the study region. A focus over Jeddah station reveals that the RCM simulated well the peak and amount of rainfall for both spells. However, the first peak is 1-day shifted, whilst the second peak is underestimated.


Xu W.,Zhejiang Sci-Tech University | Wang X.,Columbia University | Wang X.,King Abdulaziz University
IEEE Journal on Selected Areas in Communications | Year: 2012

We address the problem of downlink beamforming for mitigating the co-channel interference in multi-cell OFDMA networks. Based on the network utility maximization framework, we formulate the problem as a non-convex optimization problem subject to the per-cell power constraints, in which a general utility function of SINR is used to characterize the network performance. To solve the problem in a distributed fashion, we devise an algorithm based on the non-cooperative game with pricing mechanism. We give a sufficient condition for the convergence of the algorithm to the Nash equilibrium (NE). Moreover, to speed up the optimization of the beam-vectors at each cell, we derive an efficient algorithm to solve the KKT conditions at each cell. We provide extensive simulation results to demonstrate that the proposed distributed multi-cell beamforming algorithm converges to an NE point in just a few iterations with low information exchange overhead. Moreover, it provides significant performance gains, especially under the strong interference scenario, in comparison with several existing multi-cell interference mitigation schemes, such as the distributed interference alignment method. © 2012 IEEE.


Li Y.,Wageningen University | Zuilhof H.,Wageningen University | Zuilhof H.,King Abdulaziz University
Langmuir | Year: 2012

Covalently attached organic layers on indium tin oxide (ITO) surfaces were prepared by the photochemical grafting with 1-alkenes. The surface modification was monitored with static water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) measurements. Hydrophobic methyl-terminated ITO surfaces can be obtained via the grafting of tetradec-1-ene, whereas the attachment of ω-functionalized 1-alkenes leads to functionalized ITO surfaces. The use of a C≡C-Ge(CH 3) 3 terminus allows for facile tagging of the surface with an azido group via a one-pot deprotection/click reaction, resulting in bio/electronically active interfaces. The combination of nonaggressive chemicals (alkenes), mild reaction conditions (room temperature), and a light-induced grafting that facilitates the direct patterning of organic layers makes this simple approach highly promising for the development of ITO-based (bio)electronic devices. © 2012 American Chemical Society.


Aly H.A.A.,King Abdulaziz University | Aly H.A.A.,Al - Azhar University of Egypt | Khafagy R.M.,Ain Shams University
Food and Chemical Toxicology | Year: 2014

The present study was aimed to investigate the mechanistic aspect of endosulfan toxicity and its protection by taurine in rat testes. Pre-treatment with taurine (100mg/kg/day) significantly reversed the decrease in testes weight, and the reduction in sperm count, motility, viability and daily sperm production in endosulfan (5mg/kg/day)-treated rats. Sperm chromatin integrity and epididymal L-carnitine were markedly decreased by endosulfan treatment. Endosulfan significantly decreased the level of serum testosterone and testicular 3β-HSD, 17β-HSD, G6PDH and LDH-X. Sperm δψm and mitochondrial cytochrome c content were significantly decreased after endosulfan. Testicular caspases-3, -8 and -9 activities were significantly increased but taurine showed significant protection from endosulfan-induced apoptosis. Oxidative stress was induced by endosulfan treatment as evidenced by increased H2O2 level and LPO and decreased the antioxidant enzymes SOD, CAT and GPx activities and GSH content. These alterations were effectively prevented by taurine pre-treatment.In conclusion, endosulfan decreases rat testes weight, and inhibits spermatogenesis and steroidogenesis. It induces oxidative stress and apoptosis by possible mechanisms of both mitochondria and non-mitochondria pathways. These data provide insight into the mode of action of endosulfan-induced toxicity and the beneficial role provided by taurine to counteract endosulfan-induced oxidative stress and apoptosis in rat testis. © 2013 Elsevier Ltd.


Objectives. Microalbuminuria has been clinically used for noninvasive evaluation of renal dysfunctions. However, it is a nonspecific marker of diabetic nephropathy (DN). Methods. This study was conducted from March 2012 to April 2013 at Biochemistry Unit, King Fahd Medical Research Center (KFMRC). In this study, urinary osteopontin, podocytes number, and levels of immunoglobulin M (IgM) were determined in 60 patients (diabetic normoalbuminuria, diabetic microalbuminuria, and nephritic syndrome) compared with healthy subjects. Results. It was found that in diabetic microalbuminuria patients have a highly significant increase in urinary IgM, osteopontin, and podocyte levels as compared to other groups. Nephrotic syndrome patients showed a moderate significant elevation of these parameters compared to control subjects. At a given specificity of 97%, podocytes yielded the highest sensitivity of all markers, 95.5%. The sensitivity was considerably higher compared to IgM and osteopontin. Podocyte number was positively correlated with serum IgM and osteopontin (r = 0.63 and 0.56), respectively. Its cutoff corresponding to the 10% coefficient of variation was most appropriate for early diagnosis of DN. Conclusion. Monitoring urinary podocyte may provide a noninvasive tool that is a sensitive, accurate, and specific biomarker of glomerular injury and can be used in combination with osteopontin and IgM to more reliably detect and monitor prognosis. © 2014 Abdulrahman L. Al-Malki.


Mahmoud W.E.,King Abdulaziz University
Polymers for Advanced Technologies | Year: 2011

Polyvinyl alcohol (PVA) with different molecular weights (8000, 14,000, and 132,000g/mol) capped lead selenide (PbSe) quantum dots (QDs) are prepared. The nanocomposites are characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM studies show that the particle size of PbSe QDs decrease with the increase in PVA molecular weight and/or PVA amount. This may be due to the increase in molecular weight inhibiting further growth of PbSe into the polymer matrix. Thermogravimetric analysis showed that the introduction of PbSe QDs into PVA decreases the crystallinity of the polymer. The optical absorption spectroscopy of prepared nanocomposites showed that the absorption peaks are strongly shifted to the lower wavelength (blue shift) from near infrared region to visible region by increasing the PVA molecular weight. The (I-V) characteristic curves of the PVA/PbSe nanocomposite films under illumination showed a photovoltaic cell-like behavior. The results indicated that as the molecular weight of polymer increases, the conversion efficiency increases. © 2010 John Wiley & Sons, Ltd.


Bokhari F.M.,King Abdulaziz University
Saudi Journal of Biological Sciences | Year: 2010

Natural feed ingredients (corn, barley and wheat bran) and compound feed (manufactured pellet) are two types of fodder used for animal feeding, especially camel in Saudi Arabia. Twenty samples of each type of fodder were collected from seven different regions and screened for the presence of fungi, aflatoxins, ochratoxin and zearalenone. Fungal isolation of natural feed ingredients yielded 10 genera and 38 species of different fungi. Compound fodder samples were contaminated with 16 genera and 32 species of fungi. Total counts of Aspergillus, Penicillium and Fusarium in the animal feed samples were ranged from 54 to 223 × 103, 31.9 to 60 × 103 and 18 to 29 × 103 CFU/g, respectively. These isolates when tested for aflatoxin, ochratoxin and zearalenone producing ability, revealed this property in only four isolate, identified as Aspergillus flavus, A. parasiticus, A. ochraceus and Fusarium graminaerum. The percentage of toxigenic fungi was ranged from 5.5% to 30% for natural feed ingredients and from 4.5% to 20% for compound feed. The incidence of aflatoxins (AFT) in samples of natural feed ingredients was found to be ranged from 1 to 24.8 ppb, ochratoxin A (OTA) ranged from 1 to 44 ppb and zearalenone (ZON) ranged from 1 to 23 ppb. Contamination of compound feed with aflatoxin and ochratoxin A was ranged from 1 to 6.4 ppb and 1 to 4.7 ppb, respectively. All samples collected were found contaminated with fungi or their toxins and natural feed samples were more contaminated compared to compound feed samples. The concentrations detected were in the allowed limit (<20 ppb) except four samples of natural feed ingredients which were above the allowed limit of the tested mycotoxins. In conclusion, feed samples were contaminated with fungi and some toxigenic isolates which were responsible about mycotoxin production. Some samples had exceeded amount of AFT, OTA and ZON and may be contaminated with other mycotoxins which mean implication of fungi in camel health problems and death in Saudi Arabia. © 2009.


El-Qoubaa Z.,CNRS Research Institute in Civil Engineering and Mechanics | Othman R.,King Abdulaziz University
Materials and Design | Year: 2015

Semi-crystalline polymers are increasingly used in structural applications where they can withstand dynamic loads. It is then, of highly importance, to measure and model their mechanical behavior over a wide range of strain rates. In this paper, the polyetheretherketone's yield stress is investigated under quasi-static (0.0001-0.1/s), intermediate (5-500/s) and high (500-10,000/s) strain rates. Four experimental set-ups were used to achieve this task. It was shown that the mechanical behavior is highly sensitive to strain rate. The yield stress at 10,000/s is 115% higher than at 0.0001/s. Moreover, the strain rate sensitivity increases with increasing strain rate. A new three-material-constant constitutive equation is proposed to take into account the increase of strain rate sensitivity at very high strain rates. An identification approach is also developed to consider the influence of the strain rate range. The material constants, of the new constitutive equation and of three constitutive equations available in the literature, are identified. For each equation, we have reported the strain rate range where each model best fits the experimental data. The new model gives the best trade-off of fitting the experimental data with a good accuracy while minimizing the number of material constants. © 2014 Elsevier Ltd.


Xiang Q.,Huazhong Agricultural University | Cheng B.,Wuhan University of Technology | Yu J.,Wuhan University of Technology | Yu J.,King Abdulaziz University
Angewandte Chemie - International Edition | Year: 2015

The production of solar fuel through photocatalytic water splitting and CO2 reduction using photocatalysts has attracted considerable attention owing to the global energy shortage and growing environmental problems. During the past few years, many studies have demonstrated that graphene can markedly enhance the efficiency of photocatalysts for solar-fuel generation because of its unique 2D conjugated structure and electronic properties. Herein we summarize the recent advances in the application of graphene-based photocatalysts for solar-fuel production, including CO2 reduction to hydrocarbon fuel and water splitting to H2. A brief overview of the fundamental principles for splitting of water and reduction of CO2 is given. The different roles of graphene in these graphene-based photocatalysts for improving photocatalytic performance are discussed. Finally, the perspectives on the challenges and opportunities for future research in this promising area are also presented. There's always the sun: Graphene-based photocatalysts for solar-fuel production are of significant interest in solving the global energy problem. The recent advances in the fabrication and application of graphene-based photocatalysts, including photocatalytic reduction of CO2 to hydrocarbon fuels and photocatalytic splitting of water to H2 are explored. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Saddick S.Y.,King Abdulaziz University
Saudi Journal of Biological Sciences | Year: 2013

Elevated progesterone concentration during pregnancy and use of progesterone-like contraceptives are known to reduce ovarian cancers. This study was undertaken to decipher whether or not there is any relationship between progesterone (also oestrogen)-mediated ovarian surface epithelium (OSE) apoptosis and expression of p53, a cell-cycle arresting protein and potential tumour suppressor. Immunohistochemical staining with cytokeratin confirmed epithelial nature of the cells in the OSE layer and inclusion cysts that invaginate inside stroma after ovulation takes place. The in situ apoptosis index was determined during oestrus, and at mid and late-pregnancy stages in heifers. Epithelia of both tissues exhibited significantly high nuclear staining, suggesting that these cells are aiming to apoptotic destruction. To further establish a role of progesterone, the OSE cells were exposed in vitro to two concentrations of oestrogen and progesterone. It was revealed that progesterone at both concentrations and oestrogen only at high concentration converted a large proportion of these cells apoptotic. The stimulatory effect of progesterone (and to some extent oestrogen) was also seen on p53 expression in the same cultivated OSE cells. The steroid dosage dependence for apoptosis and p53 expression was also somewhat similar. Assuming that progesterone action is mediated through p53-caused apoptosis as a mechanism to evade malignant transformation of OSE cells, p53 expression at mRNA and protein level was investigated in the OSE layer in proximity to stroma, antrum and corpus luteum (CL). In cycling animals CL produces a large amount of progesterone and also oestrogen to maintain the post-ovulatory cycle and to suppress the gonadotropin production. Hence, cells undergoing re-epithelialization and which are in contact with CL were expected to undergo maximum apoptotic modification. Indeed we got the maximum p53/p53 gene expression in these cells. We conclude that progesterone during cycling and pregnancy may reduce the risk of developing ovarian cancer by ceasing cell cycle and diverting damaged and mutagenized OSE cells for apoptosis, and the process may be mediated through elevated p53 synthesis. However, it is also possible that progesterone and p53-induced apoptosis may be entirely different cancer suppressive actions but coincidently happening together. © 2013.


Al Agili D.E.,King Abdulaziz University | Park H.-K.,Health Science University
Journal of School Health | Year: 2012

Background: Adolescent tobacco use has been a serious public health issue, resulting in longer duration of tobacco use and higher nicotine dependence in adulthood. This study identified the current status of tobacco use among middle schools students in Jeddah, Saudi Arabia and the factors leading to tobacco use, to provide information on how to effectively prevent tobacco use among adolescents. Methods: A cross-sectional survey was administered to measure the prevalence of tobacco use and profile tobacco users. School selection was stratified by region, gender, and type (public or private). Altogether, 1186 seventh- to ninth-grade students were selected. Of those, 1019 questionnaires were used for analysis. Results: The mean age of the participants was 14.3 years (SD = 1.2) and boys comprised 54% of the sample. The prevalence of tobacco use among students was 9.72% with a significant difference between sexes (12.43% for boys and 6.65% for girls). Bivariate and multivariate analyses results showed that students whose families had higher income, had larger daily allowances, spent less time studying, skipped class more frequently, were less religious, spent more time out of home, drank more Coca-Cola, intended to use tobacco in the next year, and were males who were more likely to use tobacco. Conclusion: Prevention programs designed to reduce adolescent tobacco use need to consider these sociodemographic characteristics. Understanding the characteristics of adolescent tobacco users and the associated sociocultural context is critical for developing effective tobacco prevention programs targeted at adolescents. © 2012, American School Health Association.


Djennoune S.,Mouloud Mammeri University | Bettayeb M.,University of Sharjah | Bettayeb M.,King Abdulaziz University
Automatica | Year: 2013

Nowadays, the control of fractional-order system is one of the most popular topics in control theory. Recent studies have demonstrated the interest of fractional calculus both for systems modeling in many areas of science and engineering and for robust controller design. Thus, several research contributions have been devoted to the extension of control theory to fractional-order systems. Synergetic control was introduced in power electronics and other industrial processes. The benefit of this control scheme has been recognized for both integer-order linear and nonlinear systems. In this paper, a fractional-order synergetic control for fractional-order systems is proposed. Both linear and nonlinear cases are considered. The macro-variable is defined by the fractional-order integral of state variables. Optimality and stability properties are analyzed. A numerical example is investigated to confirm the effectiveness of the proposed method. © 2013 Published by Elsevier Ltd.


Jomoah I.M.,King Abdulaziz University
Scientific World Journal | Year: 2014

The present study was conducted to investigate the prevalence of musculoskeletal disorders and eye and vision complaints among the computer users of King Abdulaziz University (KAU), Saudi Arabian Airlines (SAUDIA), and Saudi Telecom Company (STC). Stratified random samples of the work stations and operators at each of the studied institutions were selected and the ergonomics of the work stations were assessed and the operators' health complaints were investigated. The average ergonomic score of the studied work station at STC, KAU, and SAUDIA was 81.5%, 73.3%, and 70.3, respectively. Most of the examined operators use computers daily for ≤ 7 hours, yet they had some average incidences of general complaints (e.g., headache, body fatigue, and lack of concentration) and relatively high level of incidences of eye and vision complaints and musculoskeletal complaints. The incidences of the complaints have been found to increase with the (a) decrease in work station ergonomic score, (b) progress of age and duration of employment, (c) smoking, (d) use of computers, (e) lack of work satisfaction, and (f) history of operators' previous ailments. It has been recommended to improve the ergonomics of the work stations, set up training programs, and conduct preplacement and periodical examinations for operators. © 2014 Ibrahim M. Jomoah.


Xia X.,University of Pretoria | Zhang J.,University of Pretoria | Elaiw A.,University of Pretoria | Elaiw A.,King Abdulaziz University
Control Engineering Practice | Year: 2011

Two formulations exist for the problem of the optimal power dispatch of generators with ramp rate constraints: the optimal control dynamic dispatch (OCDD) formulation based on control system models, and the dynamic economic dispatch (DED) formulation based on optimization. Both are useful for the dispatch problem over a fixed time horizon, and they were treated as equivalent formulations in literature. This paper first shows that the two formulations are in fact different and both formulations suffer from the same technical deficiency of ramp rate violation during the periodic implementation of the optimal solutions. Then a model predictive control (MPC) approach is proposed to overcome such a technical deficiency. Furthermore, it is shown that the MPC solutions, which are based on the OCDD framework, converge to the optimal solution of an extended version of the DED problem and they are robust under certain disturbances and uncertainties. Two standard examples are studied: the first one of a ten-unit system shows the difference between the OCDD and DED, and possible ramp rate violations, and the second one of a six-unit system shows the convergence and robustness of the MPC solutions, and the comparison with OCDD as well. © 2011 Elsevier Ltd.


Ashokkumar M.,University of Melbourne | Ashokkumar M.,King Abdulaziz University
Ultrasonics Sonochemistry | Year: 2015

Improving the quality and nutritional aspects of food is one of the key issues for healthy life of human beings. The stability during storage is an important parameter in quality assurance of food products. Various processing techniques such as high pressure, thermal, pulsed electric field and microwave have been used to prolong the shelf-life of food products. In recent years, ultrasound technology has been found to be a potential food processing technique. The passage of ultrasound in a liquid matrix generates mechanical agitation and other physical effects due to acoustic cavitation. Owing to its importance, a number of review articles and book chapters on the applications of ultrasound in food processing have been published in recent years. This article provides an overview of recent developments in ultrasonic processing of food and dairy systems with a particular focus on functionality of food and dairy ingredients. More specifically, the use of high frequency ultrasound in fat separation from milk and viscosity modification in starch systems and the use of low frequency ultrasound in generating nutritional food emulsions, viscosity modification and encapsulation of nutrients have been highlighted. The issues associated with the development of large scale ultrasonic food processing equipment have also been briefly discussed. © 2014 Elsevier B.V. All rights reserved.


Janssen H.J.,University of Munster | Steinbuchel A.,University of Munster | Steinbuchel A.,King Abdulaziz University
Biotechnology for Biofuels | Year: 2014

The idea of renewable and regenerative resources has inspired research for more than a hundred years. Ideally, the only spent energy will replenish itself, like plant material, sunlight, thermal energy or wind. Biodiesel or ethanol are examples, since their production relies mainly on plant material. However, it has become apparent that crop derived biofuels will not be sufficient to satisfy future energy demands. Thus, especially in the last decade a lot of research has focused on the production of next generation biofuels. A major subject of these investigations has been the microbial fatty acid biosynthesis with the aim to produce fatty acids or derivatives for substitution of diesel. As an industrially important organism and with the best studied microbial fatty acid biosynthesis, Escherichia coli has been chosen as producer in many of these studies and several reviews have been published in the fields of E. coli fatty acid biosynthesis or biofuels. However, most reviews discuss only one of these topics in detail, despite the fact, that a profound understanding of the involved enzymes and their regulation is necessary for efficient genetic engineering of the entire pathway. The first part of this review aims at summarizing the knowledge about fatty acid biosynthesis of E. coli and its regulation, and it provides the connection towards the production of fatty acids and related biofuels. The second part gives an overview about the achievements by genetic engineering of the fatty acid biosynthesis towards the production of next generation biofuels. Finally, the actual importance and potential of fatty acid-based biofuels will be discussed. © 2014Janßen and Steinbüchel; licensee BioMed Central Ltd.


Elsheikh Y.A.,King Abdulaziz University
Process Safety and Environmental Protection | Year: 2013

In the present study, 4 different functionalized pyrazoliums based on sulfoalkyl-pyrazolium hydrogensulfate and alkylsulfo-alakylpyrazolium hydrogensulfate were explored to catalyze biodiesel production from bitter apple oil (BAD). The results demonstrated that a longer chains catalyst of 2-(4-sulfobutyl) pyrazolium hydrogensulfate (SBPHSO4) exhibited the highest catalytic activity, which is attributed to its strong acidity. The highest yield of esters was up to 89.5% when the reaction was carried out under the conditions of 5.2 wt% of SBPHSO4, molar ratio of methanol to BAD of 15:1, 170°C, and 800 rpm for 6h. These results demonstrated that ionic liquids offer a promising new type of pyrazolium catalyst for biodiesel production. The use of clean ionic liquids in preparing clean biodiesel could solve the drawbacks associated with using the old conventional catalysts and might be employed as an efficient catalyst for such relevance. © 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.


Alwaal A.,University of California at San Francisco | Alwaal A.,King Abdulaziz University | Zaid U.B.,University of California at San Francisco | Lin C.-S.,University of California at San Francisco | Lue T.F.,University of California at San Francisco
Advanced Drug Delivery Reviews | Year: 2015

Erectile Dysfunction (ED) is a common disease that typically affects older men. While oral type-5 phosphodieserase inhibitors (PDE5Is) represent a successful first-line therapy, many patients do not respond to this treatment leading researchers to look for alternative treatment modalities. Stem cell (SC) therapy is a promising new frontier for the treatment of those patients and many studies demonstrated its therapeutic effects. In this article, using a Medline database search of all relevant articles, we present a summary of the scientific principles behind SCs and their use for treatment of ED. We discuss specifically the different types of SCs used in ED, the methods of delivery tested, and the methods attempted to enhance SC therapy effect. In addition, we review the current preclinical literature on SC therapy for ED and present a summary of its findings in addition to the single clinical trial published. © 2014 Elsevier B.V.


Al-Ahmary K.M.,King Abdulaziz University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014

Charge transfer (CT) complexes formed between 2,3-aminopyridine (2,3-DAP) as electron donor with the π-electron acceptors chloranilic acid (CHA) and dihydroxy-p-benzoquinone (DHBQ) were investigated spectrophotometrically in ethanol. Minimum-maximum absorbance method has been used for estimating the formation constants of the charge transfer reactions (KCT). Job's method of continuous variation and photometric titration studies were used to detect the stoichiometric ratios of the formed complexes and they showed that 1:1 complexes were produced. The molar extinction coefficient (ε), oscillator strength (f), dipole moment (μ), charge transfer energy (E CT), ionization potential (IP) and the dissociation energy (W) of the formed complexes were estimated, they reached acceptable values suggesting the stability of the formed CT-complexes. The solid CT-complexes were synthesized and characterized by elemental analyses, 1H NMR and FTIR spectroscopies where the formed complexes included proton and electron transfer. © 2013 Elsevier B.V. All rights reserved.


Szolnoki A.,Hungarian Academy of Sciences | Perc M.,University of Maribor | Perc M.,King Abdulaziz University
Journal of the Royal Society Interface | Year: 2015

The pursuit of highest payoffs in evolutionary social dilemmas is risky and sometimes inferior to conformity. Choosing the most common strategy within the interaction range is safer because it ensures that the payoff of an individual will not be much lower than average. Herding instincts and crowd behaviour in humans and social animals also compel to conformity in their own right. Motivated by these facts, we here study the impact of conformity on the evolution of cooperation in social dilemmas.We show that an appropriate fraction of conformists within the population introduces an effective surface tension around cooperative clusters and ensures smooth interfaces between different strategy domains. Payoff-driven players brake the symmetry in favour of cooperation and enable an expansion of clusters past the boundaries imposed by traditional network reciprocity. Thismechanismworks even under themost testing conditions, and it is robust against variations of the interaction network as long as degree-normalized payoffs are applied. Conformity may thus be beneficial for the resolution of social dilemmas. © 2014 The Author(s) Published by the Royal Society. All rights reserved.


Karim S.,Jamia Millia Islamia University | Karim S.,King Abdulaziz University
Asian Pacific Journal of Cancer Prevention | Year: 2014

Background: Differences in clinicopathological characteristics of gastric cancer (GC) between young and older patients are controversial and a matter of debate. Determining the statistical significance of clinicopathological information with respect to age might provide clues for better management and treatment of GC. Materials and Methods: A total of 103 Indian GC patients were enrolled for study and specimens were classified according to the AJCC-TNM system. Patients were grouped into two age-wise categories, young patients (<40 years; n=13) and older patients (≥40 years, n=90). The clinicopathological features of both groups were retrospectively examined and compared. p53 alterations were analyzed by polymerase chain reaction-single strand conformational polymorphism and immunohistochemistry methods at gene and protein levels respectively. The cases were considered p53 over-expressed if it was present in more than 25% of the tumor cells and p53 alterations was correlated with the clinicopathological characteristics of the patients as well as etiological factors for GC in both groups. Results: We found significant association of young patients with cancer stage (p=0.01), and very strong association with histology grade (p=0.064) and poorly differentiated (p=0.051) state of GC. However, neither young nor elderly patients showed associations with location, gender, etiological factors and p53 expression and alteration. Overall the male-to-female ratio of GC patients was 3.12 and the value was higher in the young (5.5) than in the older group (2.91). Conclusions: Clinicopathological features of GC like cancer stage, cell differentiation and histological grades were significantly different among young and old age cohorts. We observed a male predominance among the young group that decreased significantly with advancing age. More awareness of GC onset is required to detect cancer at an early stage for successful treatment.


Sanchez R.S.,Jaume I University | Gonzalez-Pedro V.,Jaume I University | Lee J.-W.,Sungkyunkwan University | Park N.-G.,Sungkyunkwan University | And 4 more authors.
Journal of Physical Chemistry Letters | Year: 2014

Characteristic times of perovskite solar cells (PSCs) have been measured by different techniques: transient photovoltage decay, transient photoluminescence, and impedance spectroscopy. A slow dynamic process is detected that shows characteristic times in the seconds to milliseconds scale, with good quantitative agreement between transient photovoltage decay and impedance spectroscopy. Here, we show that this characteristic time is related with a novel slow dynamic process caused by the peculiar structural properties of lead halide perovskites and depending on perovskite crystal size and organic cation nature. This new process may lie at the basis of the current-voltage hysteresis reported for PSCs and could have important implications in PSC performance because it may give rise to distinct dynamical behavior with respect to other classes of photovoltaic devices. Furthermore, we show that low-frequency characteristic time, commonly associated with electronic carrier lifetime in other photovoltaic devices, cannot be attributed to a recombination process in the case of PSCs. © 2014 American Chemical Society.


Sayed A.A.R.,King Abdulaziz University | Sayed A.A.R.,Minia University
European Review for Medical and Pharmacological Sciences | Year: 2012

Background: Diabetic nephro-pathy (DN) is a major cause of morbidity and mortality in diabetic patients. To prevent the development of this disease and to improve advanced kidney injury, effective therapies directed toward the key molecular target are reIuired. Proanthocyanidin (PA) and thymoIuinone (TQ) have been reported to be effective in treating DN, while little is known about their mechanism of action and their combination. Aim: This study was designed to investigate the possible beneficial effects of (TQ), (PA) and their combination to attenuate DN in rats. Materials and Methods: Rats were divided into five groups: group 1 (control), group 2 (diabetic untreated), group 3 (diabetic treated with PA), group 4 (diabetic treated with TQ) and group 5 (diabetic treated with PA+TQ). Diabetes was induced in groups 2-5 by a single dose of 65 mg/kg streptozotocin (STZ) in citrate buffer pH 4.5. Two days after STZ treatment, development of diabetes in the experimental groups was confirmed by measuring blood glucose. Rats in group 3 were given PA (250 mg/kg), rats in group 4 were given TQ (50 mg/kg) and rats in group 5 were given PA+TQ (250+50 mg/kg respectively) once a day orally for 12 weeks starting 2 days after STZ injection. Results: In this work, novel data correlate the relation between reactive oxygen species; advanced glycation end products; IL-6 and DN were obtained. Treatment of rats in groups 3-5 with PA, TQ and PA+TQ was significantly increased- the reduced body weight, the reduced glutathione concentration and activity of superoxide dismutase. The elevated levels of urea, creatinine, nitric oxide, malondialdehyde and IL-6 in group 2 were significantly reduced as a result of the treatment. Conclusion: These findings suggest that PA and TQ treatment exerts a therapeutic protective effect in diabetes by decreasing oxidative stress and attenuating DN. ConseIuently, TQ and PA may be clinically useful for protecting diabetic kidney against oxidative stress.


Al-Sayyad M.J.,King Abdulaziz University
Journal of Pediatric Orthopaedics | Year: 2012

BACKGROUND: Taylor spatial frame (TSF) is a modern multiplanar external fixator that combines ease of application and computer accuracy; it provides the capability of 1 to 6 axes of deformity correction sequentially or simultaneously by adjusting 6 connecting struts between 2 circular rings. Previous reports have documented the effectiveness of the TSF in acute fracture care, nonunion treatment, and in bone lengthening and deformity correction in the lower extremity. To the authors' knowledge, no previous case series in the English literature have documented the use of the TSF in treating upper extremity conditions. Our experience with the use of this external fixator in the treatment of upper extremity length abnormality, angulation, and bone transport is summarized. METHODS: Over a period of 7 years, TSF was used in 12 patients with varying upper extremity pathologies that were collected from our prospective external fixator database. The classic TSF planning strategy was adopted and the TSF web-based program was used. All cases were followed for a minimum of 2 years. The database and radiographs were reviewed to obtain demographic data, malalignment parameters, final correction, time in the TSF, and complications. RESULT: Patients' ages ranged from 8 to 18 years. Eight humeral and 4 radial cases were identified. These included 4 cubitus varus and 1 cubitus valgus deformity, 1 neglected supracondylar fracture, 2 humeral nonunion, 2 radial malunion cases, and 1 radial shaft septic nonunion. Time in the TSF varied according to patient age and bone involved. Five patients had superficial pin site infections that resolved with oral antibiotics. Postoperatively mean final angulation on the anteroposterior radiograph was 1 degree (range, 0 to 5 degrees) and the mean final angulation on the lateral radiograph was 0.5 degrees (range, 0 to 2 degrees). Union of bone was achieved in all cases. CONCLUSIONS: The TSF is an external fixator that can be successfully used as a treatment alternative for the definitive treatment of upper extremity conditions involving a deformity and or shortening or bone transport in the pediatric and adolescent patient population. LEVEL OF EVIDENCE: Level IV. Copyright © 2012 by Lippincott Williams & Wilkin.


The present study was established to evaluate the potential of insect growth regulator on the growth and development of Tribolium confusum Azadirachtin, a neem derivative which considered as insect growth regulator due to its chitin inhibitor activity was tested topically at four doses (0.5, 1, 1.5 and 2 μg insect-1) on adults of Tribolium confusum (Coleoptera: Tenebrionidae) and first evaluated on fecundity, hatchability and viability of eggs, longevity and morphometric of oocytes. Results show that the compound reduces the longevity and the fecundity. Generally, treatment with azadidrachtin affected growth and development of oocytes and egg-viability as shown by calculating the number of oocytes per ovaries and the size of basal follicle. The width of the follicle has not been affected significantly by these treatments. In the second group of experiments, this IGRs don't induce significant reduction in percentage of hatchability, the hatching rate of eggs laid by Fl females was not affected by the treatment (F = 2.86, DF = 99, p = 0.5) but it affect very significantly the viability rate of eggs laid by first female generation Fl (F = 7.5, DF = 99, p>0.0001). However, the azadirachtin lengthened very significantly the total duration of life cycle. Duration of the embryonic and post embryonic development of eggs laid by treated female increase when the concentration varied from 0 to 2 μLl. This data confirm the efficiency of growth regulators derived from neem plant, on the development of stored product insect pests. © 2011 Academic Journals Inc.


Makhdom A.M.,Shriners Hospital for Children | Makhdom A.M.,King Abdulaziz University | Hamdy R.C.,Shriners Hospital for Children
Tissue Engineering - Part B: Reviews | Year: 2013

The distraction osteogenesis (DO) technique has been used worldwide to treat many complex orthopedic and craniofacial conditions. One limitation of this technique is the long time of fixator needs to be left in place until the bone is completely consolidated. Various biophysical, mechanical, and biological methods have been investigated to accelerate bone regeneration during DO. Several growth factors (GFs) are known to enhance bone regeneration such as bone morphogenic proteins, transforming growth factor beta, fibroblast growth factor, insulin growth factor, vascular endothelial growth factor, and platelet-derived growth factor. These GFs are known to stimulate cellular growth, proliferation, migration, and differentiation. In this review, an extensive overview of these GFs development and applications on acceleration of bone regeneration in the context of DO is discussed. Current challenges and alternative tissue engineering techniques to address the delivery and sustain release of these factors are also discussed. Finally, we highlighted our view regarding the remaining questions and future research directions. © Copyright 2013, Mary Ann Liebert, Inc. 2013.


Van Der Schrier G.,Royal Netherlands Meteorological Institute | Barichivich J.,University of East Anglia | Briffa K.R.,University of East Anglia | Jones P.D.,University of East Anglia | Jones P.D.,King Abdulaziz University
Journal of Geophysical Research: Atmospheres | Year: 2013

Global maps of monthly self-calibrating Palmer Drought Severity Index (scPDSI) have been calculated for the period 1901-2009 based on the CRU TS 3.10.01 data sets. This work addresses some concerns with regard to monitoring of global drought conditions using the traditional Palmer Drought Severity Index. First, the scPDSI has a similar range of variability in diverse climates making it a more suitable metric for comparing the relative availability of moisture in different regions. Second, the more physically based Penman-Monteith parameterization for potential evapotranspiration is used, calculated using the actual vegetation cover rather than a reference crop. Third, seasonal snowpack dynamics are considered in the water balance model. The leading mode of variability in the new data set represents a trend towards drying conditions in some parts of the globe between 1950 and 1985 but accounts for less than 9% of the total variability. Increasing temperature and potential evapotranspiration explain part of the drying trend. However, local trends in most of the drying regions are not significant. Previously published evidence of unusually strong or widespread drying is not supported by the evidence in this work. A fundamental aspect of the calculation of scPDSI is the selection of a calibration period. When this period does not include the most recent part of the record, trends towards more extreme conditions are amplified. It is shown that this is the principal reason for different published interpretations of the scale of recent global drying and not, as recently claimed, the use of simplified forcing data. Key PointsEvidence for strong or widespread drying is not supported by this workA new global dataset quantifying global drought and wet spells is releasedEvapotranspiration and snowpack dynamics are treated realistically ©2013. American Geophysical Union. All Rights Reserved.


Wang Z.,Tsinghua National Laboratory for Information Sciences and Technology | Wang Q.,Tsinghua National Laboratory for Information Sciences and Technology | Chen S.,University of Southampton | Chen S.,King Abdulaziz University | Hanzo L.,University of Southampton
Optics Express | Year: 2014

Orthogonal frequency-division multiplexing (OFDM) has been widely used in visible light communication systems to achieve high-rate data transmission. Due to the nonlinear transfer characteristics of light emitting diodes (LEDs) and owing the high peak-to-averagepower ratio of OFDM signals, the transmitted signal has to be scaled and biased before modulating the LEDs. In this contribution, an adaptive scaling and biasing scheme is proposed for OFDM-based visible light communication systems, which fully exploits the dynamic range of the LEDs and improves the achievable system performance. Specifically, the proposed scheme calculates near-optimal scaling and biasing factors for each specific OFDM symbol according to the distribution of the signals, which strikes an attractive trade-off between the effective signal power and the clipping-distortion power. Our simulation results demonstrate that the proposed scheme significantly improves the performance without changing the LED's emitted power, while maintaining the same receiver structure. © 2014 Optical Society of America.


Aazam E.S.,King Abdulaziz University
Journal of Industrial and Engineering Chemistry | Year: 2014

Ag2S nanoparticles were prepared using a hydrothermal method, and Ni was doped via a photo-assisted deposition method. The samples produced were characterized using different tools. Furthermore, the catalytic performance of the Ag2S and Ni/Ag2S samples was examined in the degradation of methylene blue dye under visible light. The UV-vis spectral analysis detected a red shift after loading of Ni. The maximum degradation efficiency achieved was 100% with 3wt% Ni/Ag2S as the photocatalyst after a 40-min reaction time. The catalyst could be reused without any loss in activity for the first five cycles. © 2014 The Korean Society of Industrial and Engineering Chemistry.


Hirokawa N.,University of Tokyo | Hirokawa N.,King Abdulaziz University | Tanaka Y.,University of Tokyo
Experimental Cell Research | Year: 2015

Kinesin superfamily proteins (KIFs) largely serve as molecular motors on the microtubule system and transport various cellular proteins, macromolecules, and organelles. These transports are fundamental to cellular logistics, and at times, they directly modulate signal transduction by altering the semantics of informational molecules. In this review, we will summarize recent approaches to the regulation of the transport destinations and to the physiological relevance of the role of these proteins in neuroscience, ciliary functions, and metabolic diseases. Understanding these burning questions will be essential in establishing a new paradigm of cellular functions and disease pathogenesis. © 2015 Elsevier Inc.


Al-Turaif H.A.,King Abdulaziz University
Progress in Organic Coatings | Year: 2013

The effects of ultraviolet (UV) radiation on the surface morphology and the surface chemistry of an epoxy-resin-based coating were characterized with both scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The techniques were applied to follow the chemical changes that occur after different UV-exposure periods. SEM images indicated the generation of "silver cracks" on the surface of the coating as a result of UV-exposure. The shape and width of the cracks were highly related to the UV-exposure period. XPS revealed that the main carbon peak had an unsymmetrical shape due to the large variation in the type of the carbon bonds in the chemical structure of the epoxy resin. Evidence of an oxidation degradation process was observed on the coating surface. The longer the exposure of the coating to UV radiation, the more oxygen bonds were formed, causing the oxygen content to increase and the carbon concentration to decrease. XPS-peak fittings for four carbon bonds were conducted. Results indicated the cleavage of aliphatic carbon-hydrogen (CH) and hydroxyl (COH) bonds side by side with the formation of carbonyl (CO) and carboxyl (COO) bonds. These changes that occurred on the surface of the epoxy-based coating were stopped after a specific UV-exposure period of time. © 2013 Elsevier B.V. All rights reserved.


Ibrahim N.K.,King Abdulaziz University
The Libyan journal of medicine | Year: 2013

Irritable bowel syndrome (IBS) is a frequent, costly, and potentially disabling gastrointestinal disorder. Medical education is among the most challenging and the most stressful education, and this may predispose to high rates of IBS. To determine the prevalence and predictors of IBS among medical students and interns in King Abdulaziz University, Jeddah, Saudi Arabia. A cross-sectional study was conducted among 597 medical students and interns selected by multistage stratified random sample method in 2012. A confidential, anonymous, and self-administered questionnaire was used to collect personal and sociodemographic data, level of emotional stress, and food hypersensitivity during the past 6 months. Rome III Criteria and the Standardized Hospital Anxiety and Depression Scale were also used. The prevalence of IBS was 31.8%. Multiple logistic regression analysis revealed that the first predictor of IBS was female gender (aOR=2.89; 95.0% CI: 1.65-5.05). The second predictor was presence of morbid anxiety (aOR=2.44; 95.0% CI: 1.30-4.55). Living in a school dormitory, emotional stress during 6 months preceding the study, and the academic year were the next predictors. High prevalence of IBS prevailed among medical students and interns. Female gender, morbid anxiety, living in school dormitory, emotional stress, and higher educational level (grade) were the predictors of IBS. Screening of medical students for IBS, psychological problems, and reducing stress by stress management are recommended.


Aljahdali M.,Northern Borders University | Aljahdali M.,King Abdulaziz University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

The ternary complexes of Cu(II), Zn(II), Ni(II) and Cd(II) with 2-aminomethylbenzimidazole (AMBI) and glycine as a representative example of amino acids have been isolated and characterized by elemental analyses, IR, ESR, UV-vis, magnetic moment, molar conductance and 1H NMR spectra. AMBI behaves as neutral bidentate ligands with coordination through imidazole and amino group nitrogens while the glycine amino acid behaves as a monodenate anion with coordination involving the amino group and carboxylate oxygen after deprotonation. The magnetic and spectral data indicates a square planar geometry for both Cu2+ and Ni2+ complexes and a tetrahedral geometry for both Zn2+ and Cd2+ complexes. The isolated chelates have been screened for their antifungal and antibacterial activities using the disc diffusion method. A cytotoxicity of the compounds against colon (HCT116) and larynx (HEP2) cancer cells have been studied. The stability constants of ternary M-AMBI-Gly complexes were determined potentiometrically in aqueous solution at I = 0.1 mol dm-3 NaCl. © 2013 Elsevier B.V. All rights reserved.


Al-Turaif H.A.,King Abdulaziz University
Progress in Organic Coatings | Year: 2013

The effect of the addition of nanofibrillated cellulose (NFC) on the tensile properties of epoxy resin was investigated. NFC was added to the epoxy resin at different weight percentages (0.05, 0.1, 0.2, 0.25, 0.5 and 1%). The tensile properties, including, strength, elongation, toughness and Young modulus, were investigated. Adaptive speckle imaging interferometry (ASII) was used to study the relationship between the film formation kinetics and the tensile properties of the epoxy composites. In addition, scanning electron microscopy (SEM) was used to investigate the morphology of the formed composite to better understand the proposed relationship. The addition of NFC to the epoxy resin significantly improves the tensile properties of the epoxy composite. The largest increase was found at the addition level of 0.1%. At this level, the maximum stress increased by 120%, the strain to failure increased by 73%, the toughness increased by 300% and the Young modulus increased by 64% in comparison to the pure epoxy resin. During drying, the shortest interdiffusion stage occurs at the optimum level of NFC (0.1%). The extent of interdiffusion is related to the tensile strength build up in the epoxy coating film and the amount of fibers present. SEM revealed the excellent adhesion of fibers in the optimum filler content. However, the additional NFC led the resultant NFC-epoxy matrix to exhibit fiber agglomeration, which affects the matrix strength and decreases the tensile properties. © 2012 Elsevier B.V.


Baumeister R.F.,Florida State University | Baumeister R.F.,King Abdulaziz University | Baumeister R.F.,VU University Amsterdam
Neuropsychologia | Year: 2014

Inhibition is a major form of self-regulation. As such, it depends on self-awareness and comparing oneself to standards and is also susceptible to fluctuations in willpower resources. Ego depletion is the state of reduced willpower caused by prior exertion of self-control. Ego depletion undermines inhibition both because restraints are weaker and because urges are felt more intensely than usual. Conscious inhibition of desires is a pervasive feature of everyday life and may be a requirement of life in civilized, cultural society, and in that sense it goes to the evolved core of human nature. Intentional inhibition not only restrains antisocial impulses but can also facilitate optimal performance, such as during test taking. Self-regulation and ego depletion- may also affect less intentional forms of inhibition, even chronic tendencies to inhibit. Broadly stated, inhibition is necessary for human social life and nearly all societies encourage and enforce it. © 2014 Elsevier Ltd.


The thermal performance of a passive single basin solar still was investigated by computer simulation using the climatic conditions of Jeddah (lat. 21° 42' N, long. 39° 11' E), Saudi Arabia under the two conditions: (a) the temperatures of the inner Tgi and outer Tgo surfaces of the still cover are equal and (b) the temperatures of the inner Tgi and outer Tgo surfaces of the still cover are not equal. Effect of wind speed V on the daily productivity Pd of the still for these conditions was studied. It was indicated that for the condition Tgi = Tgo, there is a critical mass (depth) of basin water beyond which Pd increases as V increases until a typical velocity Vt. For basin water masses less than the critical mass, Pd was found to decrease with increasing V until Vt. After Vt, the change in Pd becomes insignificant. When Tgi ≠ Tgo, Pd was found to be less dependent on wind speed V for all investigated values of mass of basin water mw in the range 0 < mw ≤ 100 kg. The rate of heat transfer by forced convection due to wind should be estimated on the basis of the temperature of the upper surface of the still cover. © 2011 Elsevier Ltd.


Al-Maghrabi J.A.,King Abdulaziz University
Saudi Medical Journal | Year: 2011

Castleman's disease (CD) is an unusual lymphoproliferative disorder that may mimic lymphoma clinically and pathologically. It is classified clinically as localized and multicentric types, and pathologically as hyaline vascular and plasma cell types. It is associated with increased risk of lymphoma and follicular dendritic cell tumors. The pathogenesis of CD is still controversial and complex. Active research is ongoing to highlight more on the etiopathogenesis of this entity. The aim of this article is to review the literature on pathogenesis of CD and to focus on the possible role of viruses in the development of this disease.


McClements D.J.,University of Massachusetts Amherst | McClements D.J.,King Abdulaziz University | Xiao H.,University of Massachusetts Amherst
Food and Function | Year: 2014

The oral bioavailability of many lipophilic bioactive agents (pharmaceuticals and nutraceuticals) is limited due to various physicochemical and physiological processes: poor release from food or drug matrices; low solubility in gastrointestinal fluids; metabolism or chemical transformation within the gastrointestinal tract; low epithelium cell permeability. The bioavailability of these agents can be improved by specifically designing food matrices that control their release, solubilization, transport, metabolism, and absorption within the gastrointestinal tract. This article discusses the impact of food composition and structure on oral bioavailability, and how this knowledge can be used to design excipient foods for improving the oral bioavailability of lipophilic bioactives. Excipient foods contain ingredients or structures that may have no bioactivity themselves, but that are able to promote the bioactivity of co-ingested bioactives. These bioactives may be lipophilic drugs in pharmaceutical preparations (such as capsules, pills, or syrups) or nutraceuticals present within food matrices (such as natural or processed foods and beverages). This journal is © the Partner Organisations 2014.


Wubbeler J.H.,University of Munster | Steinbuchel A.,University of Munster | Steinbuchel A.,King Abdulaziz University
Current Opinion in Biotechnology | Year: 2014

Polythioesters (PTE) contain sulfur in the backbone and represent persistent biopolymers, which are produced by certain chemical procedures as well as biotechnological in vitro and in vivo techniques. Different building blocks can be incorporated, resulting in PTE with variable features that could become interesting for special purposes. Particularly, the option to produce PTE in large-scale and in accordance with the methods of white biotechnology or green chemistry is valuable due to economical potentials and public environmental consciousness. This review is focused on the synthesis of PTE by the three established bacterial production strains Ralstonia eutropha, Escherichia coli and Advenella mimigardefordensis. In addition, an overview of the in vitro production and degradation of PTE is depicted. © 2014 Elsevier Ltd.


Gieseking R.L.,Georgia Institute of Technology | Mukhopadhyay S.,Georgia Institute of Technology | Risko C.,Georgia Institute of Technology | Marder S.R.,Georgia Institute of Technology | And 2 more authors.
Advanced Materials | Year: 2014

All-optical switching - controlling light with light - has the potential to meet the ever-increasing demand for data transmission bandwidth. The development of organic π-conjugated molecular materials with the requisite properties for all-optical switching applications has long proven to be a significant challenge. However, recent advances demonstrate that polymethine dyes have the potential to meet the necessary requirements. In this review, we explore the theoretical underpinnings that guide the design of π-conjugated materials for all-optical switching applications. We underline, from a computational chemistry standpoint, the relationships among chemical structure, electronic structure, and optical properties that make polymethines such promising materials. Polymethine dyes have the potential to meet the stringent requirements for all-optical switching applications: that is, controlling light with light. Here, we review the theory behind the design of π-conjugated molecular materials for all-optical switching applications and examine the role of computational chemistry in exploring the optical properties of these systems © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Yaghmour S.J.,King Abdulaziz University
EPJ Applied Physics | Year: 2010

Electrical conductivity measurements of pyronine G(Y) were performed as a function of both temperature (303-443 K) and frequency (50 Hz-550 kHz). The frequency dependence of ac conductivity is well represented by the form ω8. The values of exponent, (s) decrease from 0.98 at 303 K to 0.67 at 403 K. The temperature dependence of both ac electrical conductivity and the exponent (s) reveals that the ac conduction is due to the correlated barrier hopping (CBH). The dielectric constant, ε1 (ω) and dialectic loss, ε2(ω), have been determined for bulk pyronine G(Y). Both ε1(ω) and ε2(ω) decrease by increasing frequency and increase by increasing temperature. © 2009 EDP Sciences.


Marghalani H.Y.,King Abdulaziz University
Materials Research | Year: 2010

The aim of this study was to evaluate the effect of post-irradiation dry aging at different periods of time on Vickers microhardness of some dental composites based on various resin matrices. Sixty four disc-shaped specimens of the resin composites were prepared in a split Tefon mold (8 × 2 mm) and irradiated by Optilux 501 light cure (500 mW.cm-2 for 40 seconds) on their top side. The specimens were aged-dry in dark at 23 and 37 °C for the following storage periods; immediate, 1/2 an hour, 1, 6, 12, 24, 48 and 168 hours. The microhardness values were recorded using a Vickers Hardness Tester at 300 g load for 15 seconds. Results showed that Filtek® P90 and Defnite expressed the highest hardness value followed by Tetric Evoceram and then Premise Enamel. At each aging period, all materials demonstrated signifcant differences between hardness values of top and base surfaces as well as both temperatures examined (P < 0.05). In conclusion, surface hardness developed gradually in most of the materials reaching optimum after 168 hours post-irradiation aging. Dental composites based on silorane and ormocer resin matrices achieved higher Vickers microhardness than those based on dimethacrylates resin.


Oh D.-H.,University of Illinois at Urbana - Champaign | Oh D.-H.,Gyeongsang National University | Dassanayake M.,University of Illinois at Urbana - Champaign | Bohnert H.J.,University of Illinois at Urbana - Champaign | And 3 more authors.
Genome Biology | Year: 2012

Extremophile plants thrive in places where most plant species cannot survive. Recent developments in high-throughput technologies and comparative genomics are shedding light on the evolutionary mechanisms leading to their adaptation. © 2012 BioMed Central Ltd.


Proctor C.M.,University of California at Santa Barbara | Love J.A.,University of California at Santa Barbara | Nguyen T.-Q.,University of California at Santa Barbara | Nguyen T.-Q.,King Abdulaziz University
Advanced Materials | Year: 2014

Analysis of measured charge-carrier mobilities and fill factors in solution-processable small-molecule bulk-heterojunction solar cells reveals that in order to achieve a high FF, the hole and electron mobilities must be >10-4 cm 2 V-1 s-1. Neat-film mobility measurements are also found to be a useful predictor of the maximum blend film mobility and FF obtained in blend film solar cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zenkour A.M.,King Abdulaziz University | Alghamdi N.A.,Riyadh Girls College of Education
Mechanics of Advanced Materials and Structures | Year: 2010

The bending response of sandwich plates subjected to thermo-mechanical loads is studied. The sandwich plate faces are assumed to have isotropic, two-constituent (metal-ceramic) material distribution through the thickness, and the modulus of elasticity, Poisson's ratio, and thermal expansion coefficient of the faces are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. Several kinds of sandwich plates are used, taking into account the symmetry of the plate and the thickness of each layer. Field equations for functionally graded sandwich plates whose deformations are governed by either the shear deformation theories or the classical theory are derived. Displacement functions that identically satisfy boundary conditions are used to reduce the governing equations to a set of coupled ordinary differential equations with variable coefficients. Exact solutions for functionally graded materials (FGMs) sandwich plates are presented. Numerical results of the sinusoidal, third-order, first-order, and classical theories are presented to show the effect of material distribution on the deflections and stresses. A wide variety of results is presented for the static response of sandwich plates under thermo-mechanical loads. The effects of thermo-mechanical loads and other parameters on the dimensionless deflections and axial and transverse shear stresses of an FGM sandwich plate are studied. Copyright © Taylor & Francis Group, LLC.


Bredas J.-L.,Georgia Institute of Technology | Bredas J.-L.,King Abdulaziz University
Materials Horizons | Year: 2014

The energy gap between the highest occupied and lowest unoccupied electronic levels is a critical parameter determining the electronic, optical, redox, and transport (electrical) properties of a material. However, the energy gap comes in many flavors, such as the band gap, HOMO-LUMO gap, fundamental gap, optical gap, or transport gap, with each of these terms carrying a specific meaning. Failure to appreciate the distinctions among these different energy gaps has caused much confusion in the literature, which is manifested by the frequent use of improper terminology, in particular, in the case of organic molecular or macromolecular materials. Thus, it is our goal here to clarify the meaning of the various energy gaps that can be measured experimentally or evaluated computationally, with a focus on π-conjugated materials of interest for organic electronics and photonics applications. © The Royal Society of Chemistry.


Alshaikhi A.,King Abdulaziz University | Barman S.,se National Center For Basic Science | Srivastava G.P.,University of Exeter
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We report on a systematic theoretical investigation of the lattice thermal conductivity of several GaN samples (bulk and films) over a wide range of temperature, by applying Callaway's relaxation-time theory in its full form and Srivastava's scheme for anharmonic three-phonon scattering processes. The role of the usually neglected three-phonon normal-drift term has been quantified. We have attempted to quantify the role of phonon scattering by various defects and imperfections, present in the film samples, in controlling the temperature dependence of thermal conductivity. We find that except for the purest sample, the phonon-impurity scattering plays a significant role in controlling the thermal conductivity of GaN not only around the thermal-conductivity peak region but also over a very large range of temperature. It can also be predicted from our numerical study, and with available experimental results, that the highest possible thermal conductivity of bulk GaN can only be realized when point impurities such as oxygen and silicon are in small concentration (≃ 1016 cm-3 or less) and other defects are either absent (from experimental study) or present in very small concentration (our numerical study). The highest value of the room-temperature thermal conductivity is achieved for samples grown by the high-temperature and high-pressure growth technique. © 2010 The American Physical Society.


Athar H.,King Abdulaziz University
Atmospheric Science Letters | Year: 2012

Variability in the observed daily temperature for the 30-year period (1979-2008) is studied from a total of 19 stations in Saudi Arabia (SA) by calculating the empirical anomaly probability distribution functions (PDFs) on annual basis. The 30-year period is divided into three decades. As compared with the first decade, the PDFs for the remaining decades display a relative frequency rise in warmer temperatures. The mean values of the PDFs depict an average decadal positive shift of 0.83, 0.66, and 0.49 °C, for the maximum, the mean, and the minimum temperature, respectively, relative to the 30-year base value. © 2012 Royal Meteorological Society.


Alhashemi H.H.,King Abdulaziz University
Neurosciences | Year: 2010

Dysphagia, or swallowing difficulty, is a common problem following severe traumatic brain injury and is associated with an increased risk of malnutrition and pneumonia. Management of patients with dysphagia following head injury is complicated by the presence of cognitive, communication, and behavioral impairments. The purpose of this review article is to help physicians taking care of traumatic brain injury patients understand and manage dysphagia. The article reviews the history of the study of swallowing, stages of swallowing, impairments of swallowing, neural control of swallowing, and the evaluation of patients with swallowing difficulties and their management. In addition to the general principles of dysphagia management, this article covers the management of dysphagic patients with tracheostomy and their nutritional management.


Butt M.,King Abdulaziz University
GIScience and Remote Sensing | Year: 2012

The primary focus of this research is to estimate light pollution in the urban and suburban regions of Pakistan with the help of satellite remote sensing (SRS) and geographic information system (GIS) techniques. Analog maps and multi-temporal nighttime images of the Defense Meteorological Satellite Program (DMSP) onboard Operational Linescan System (OLS) sensor were used in this study. A series of direct and indirect light pollution maps of the study area were generated and analyzed. The results of the study show that in the urban environment, light pollution is mainly due to artificial nightlight sources.


Lawey A.Q.,University of Leeds | El-Gorashi T.E.H.,University of Leeds | Elmirghani J.M.H.,King Abdulaziz University
Journal of Lightwave Technology | Year: 2014

In this paper, we introduce a framework for designing energy efficient cloud computing services over non-bypass IP/WDM core networks. We investigate network related factors including the centralization versus distribution of clouds and the impact of demand, content popularity and access frequency on the clouds placement, and cloud capability factors including the number of servers, switches and routers and amount of storage required in each cloud. We study the optimization of three cloud services: cloud content delivery, storage as a service (StaaS), and virtual machines (VMS) placement for processing applications. First, we develop a mixed integer linear programming (MILP) model to optimize cloud content delivery services. Our results indicate that replicating content into multiple clouds based on content popularity yields 43% total saving in power consumption compared to power un-aware centralized content delivery. Based on the model insights, we develop an energy efficient cloud content delivery heuristic, DEER-CD, with comparable power efficiency to the MILP results. Second, we extend the content delivery model to optimize StaaS applications. The results show that migrating content according to its access frequency yields up to 48% network power savings compared to serving content from a single central location. Third, we optimize the placement of VMs to minimize the total power consumption. Our results show that slicing the VMs into smaller VMs and placing them in proximity to their users saves 25% of the total power compared to a single virtualized cloud scenario. We also develop a heuristic for real time VM placement (DEER-VM) that achieves comparable power savings. © 2013 IEEE.


Nieschlag E.,University of Munster | Nieschlag E.,King Abdulaziz University | Nieschlag S.,University of Munster
Asian Journal of Andrology | Year: 2014

The biological effects of the testes and testosterone are known since antiquity. Aristotle knew the effects of castration and his hypothesis on fertilization is one of the first scientific encounters in reproductive biology. Over centuries, castration has been performed as punishment and to produce obedient slaves, but also to preserve the soprano voices of prepubertal boys. The Chinese imperial (and other oriental) courts employed castrates as overseers in harems who often obtained high-ranking political positions. The era of testis transplantation and organotherapy was initiated by John Hunter in London who transplanted testes into capons in 1786. The intention of his experiments was to prove the 'vital principle' as the basis for modern transplantation medicine, but Hunter did not consider endocrine aspects. Arnold Adolph Berthold postulated internal secretion from his testicular transplantation experiments in 1849 in Göttingen and is thus considered the father of endocrinology. Following his observations, testicular preparations were used for therapy, popularized by self-experiments by Charles-Edouard Brown-Séquard in Paris (1889), which can at best have placebo effects. In the 1920s Sergio Voronoff transplanted testes from animals to men, but their effectiveness was disproved. Today testicular transplantation is being refined by stem cell research and germ cell transplantation. Modern androgen therapy started in 1935 when Enrest Lacquer isolated testosterone from bull testes in Amsterdam. In the same year testosterone was chemically synthesized independently by Adolf Butenandt in Göttingen and Leopold Ruzicka in Basel. Since testosterone was ineffective orally it was either compressed into subcutaneous pellets or was used orally as 17α-methyl testosterone, now obsolete because of liver toxicity. The early phases of testosterone treatment coincide with the first description of the most prominent syndromes of hypogonadism by Klinefelter, by Kallmann, DelCastillo and Pasqualini. In the 1950s longer-acting injectable testosterone enanthate became the preferred therapeutic modality. In the 1950s and 1960s, research concentrated on the chemical modification of androgens in order to emphasize their anabolic effects. Although anabolic steroids have largely disappeared from clinical medicine, they continue to live an illegal life for doping in athletics. In the 1970s the orally effective testosterone undecanoate was added to the spectrum of preparations. Recent transdermal gels and long-acting injectable preparations provide options for physiological testosterone substitution therapy. © 2014 AJA, SIMM & SJTU. All rights reserved.


Background: Patients undergoing orthognathic procedures can require blood transfusions. The objectives of this study were to evaluate the predictors of intra-operative blood loss in patients undergoing orthognathic procedures and the transfusion rates and practices of our institution.Materials and methods: This retrospective study included 92 patients who underwent the following four types of orthognathic procedures: Group 1, bimaxillary; Group 2, bimaxillary with bone grafts; Group 3, LeFort I osteotomies; and Group 4, LeFort I osteotomies with bone grafts. The intra-operative blood loss, operative time, age, gender and pre- and post-operative HGB and HCT were assessed.Results: The mean blood loss for all groups was 650 ± 397.8 mL, and there were differences in blood loss between the four groups (p = 0.211). The mean operative time was 5 hours and 32 minutes. There were no differences in intra-operative blood loss between the genders or the BMI categories. The operative time was moderately correlated with the intra-operative blood loss (p < 0.001, r =0.332). Eighteen of the 92 patients (19.5%) received blood transfusions. The mean intra-operative blood loss was higher among the patients who received transfusions (p < 0.001).Conclusions: The only predictor of intra-operative blood loss was operative time. The observed transfusion rate was higher than those that have been reported for similar procedures; thus, our institution needs to revisit our transfusion policy and use more time-efficient techniques in the operating room. © 2014 Al-Sebaei; licensee BioMed Central Ltd.


Factors regulating gastrointestinal nematode infrapopulations are to a great extent density-dependent. Here, 23 natural infrapopulations (41-281 individuals) of the viviparous nematode Procamallanus elatensis (Camallanidae) from the fish Siganus rivulatus were found distributed in a well-defined fundamental niche (posterior 55% of the intestine). Immature worms were mostly found in the anterior third of this niche, while mature worms were found in aggregations posterior to them and followed by gravid females in the posterior 20% of the intestine. This distribution strongly suggests that worms migrate towards the posterior intestine while they mature, copulate and reproduce. In small infrapopulations, the sex ratios were distinctly female-biased and the number of gravid females was low. In large infrapopulations, the sex ratios were distinctly male-biased and the number of gravid females was high. However, the mean lengths of both immature males and females and mature females decreased dramatically as the infrapopulation size increased, while those of mature males increased significantly. These results strongly suggest intraspecific competition and density-dependent regulation of mean worm length, and the increase in the mean length of mature males strongly suggests intense sexual selection and competition between mature males. Production of larvae by female worms decreased significantly as the infrapopulation size increased, suggesting a density-dependent reduction in female worm fertility. The results are statistically significant and strongly suggest that infrapopulation self-regulation is through density-dependent mechanisms, in which development of immature worms, infrapopulation size, sex ratio, sexual selection and carrying capacity of the fundamental niche play essential roles in shaping and regulating the infrapopulations. © 2011 Cambridge University Press.


Cai R.-G.,CAS Institute of Theoretical Physics | Cai R.-G.,King Abdulaziz University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We present exact analytical black hole solutions with conformal anomaly in AdS space and discuss the thermodynamical properties of these black hole solutions. These black holes can have a positive, zero and negative constant curvature horizon, respectively. For the black hole with a positive constant curvature horizon, there exists a minimal horizon determined by the coefficient of the trace anomaly, the black hole with a smaller horizon is thermodynamically unstable, while it is stable for the case with a larger horizon. The Hawking-Page transition happens in this case. For the black hole with a Ricci flat horizon, the black hole is always thermodynamically stable and there is no Hawking-Page transition. In the case of the black hole with a negative constant curvature horizon, there exists a critical value for the coefficient of the trace anomaly, under this critical value, the black hole is always thermodynamical stable and the Hawking-Page transition does not happen. When the coefficient is beyond the critical value, the black hole with a smaller horizon is thermodynamically unstable, but it becomes stable for the case with a larger horizon, the Hawking-Page transition always happens in this case. The latter is a new feature for the black holes with a negative constant curvature horizon. © 2014 The Author.


Harrat Tufail represents a Caenozoic basalt suite at the western margin of the Arabian plate. This rift-related suite includes voluminous Quaternary non-vesicular basalt (with fragments of earlier Pliocene vesicular flow) that forms a cap sheet over Miocene rhyolite and minor vesicular basalt. The contact between rhyolite and the basaltic cap is erosional with remarkable denudations indicating long time gap between the felsic and mafic eruptions. The geochemical data prove alkaline, sodic and low-Ti nature of the olivine basalt cap sheet. The combined whole-rock and mineral spot analyses by the electron microprobe (EMPA) suggest magma generation from low degree of partial melting (~5%) from spinel- and garnet-lherzolite mantle source. Derivation from a mantle source is supported by low Na content in clinopyroxene (ferroan diopside) whereas high Mg content in ilmenite is an evidence of fractional crystallization trajectory. Accordingly, the Pliocene basaltic cap of Harrat Tufail is a product of mantle melt that originates by recycling in the asthenosphere during subduction of ancient oceanic slab(s). The whole-rock chemistry suggests an ancient ocean island basaltic slab (OIB) whereas the EMPA of Al-rich spinel inclusions in olivine phenocrysts are in favour of a mid-ocean ridge basaltic source (MORB). Calculations of oxygen fugacity based on the composition of co-existing Fe-Ti oxide suggest fluctuation from highly to moderately oxidizing conditions with propagation of crystallization (log10 fO2 from -22.09 to -12.50). Clinopyroxene composition and pressure calculation indicates low-pressure (0.4-2 kbar). Cores of olivine phenocrysts formed at highest temperature (1086-1151 °C) whereas the rims and olivine micro-phenocrysts formed at 712-9-796 °C which is contemporaneous to formation of clinopyroxene at 611-782 °C. Fe-Ti oxides crystallized over a long range (652-992 °C) where it started to form at outer peripheries of olivine phenocrysts and as interstitial phase with clinopyroxene. © 2015 Elsevier Ltd.


Wali S.O.,King Abdulaziz University
Annals of Thoracic Medicine | Year: 2012

Most lung abscesses (80-90%) are now successfully treated with antibiotics; however, this conservative approach may occasionally fail. When medical treatment fails, pulmonary resection is usually advised. Alternatively, percutaneous transthoracic tube drainage or endoscopic drainage can be considered, though both remain controversial. In this communication, the medical literature focusing on percutaneous tube drainage efficacy, indications, techniques, complications, and mortality, as well as available data regarding endoscopic drainage are reviewed.


Medical Education departments oversee the process of medical education in medical schools and provide many educational services to support, evaluate and thus enhance the educational role of the medical school. Its roles revolve around research, teaching and providing educational support in areas of curriculum development and assessment. This paper provides a brief summary on the emergence of different medical education centers/units/ departments around the world from a historical perspective. Special attention will be given to the process followed in establishing the Medical Education Department (MED) in King Abdul Aziz University (KAU). This paper also explores the roles that are currently played within the department with a reflection on documented roles of the medical education departments worldwide. Special emphasis will be given to explore the current challenges faced by KAU MED and proposed suggestions to improve these challenges will also be addressed. © OMSB, 2012.


Abdelwahed M.F.,King Abdulaziz University | Abdelwahed M.F.,National Research Institute of Astronomy and Geophysics NRIAG
Computers and Geosciences | Year: 2012

Although numerous seismological programs are currently available, most of them suffer from the inability to manipulate different data formats and the lack of embedded seismological tools. SeismoGRAPHer, or simply SGRAPH, is a new system for maintaining and analyzing seismic waveform data in a stand-alone, Windows-based application that manipulates a wide range of data formats. SGRAPH was intended to be a tool sufficient for performing basic waveform analysis and solving advanced seismological problems. The graphical user interface (GUI) utilities and the Windows functionalities, such as dialog boxes, menus, and toolbars, simplify the user interaction with the data. SGRAPH supports common data formats, such as SAC, SEED, GSE, ASCII, and Nanometrics Y-format, and provides the ability to solve many seismological problems with built-in inversion tools. Loaded traces are maintained, processed, plotted, and saved as SAC, ASCII, or PS (post script) file formats. SGRAPH includes Generalized Ray Theory (GRT), genetic algorithm (GA), least-square fitting, auto-picking, fast Fourier transforms (FFT), and many additional tools. This program provides rapid estimation of earthquake source parameters, location, attenuation, and focal mechanisms. Advanced waveform modeling techniques are provided for crustal structure and focal mechanism estimation. SGRAPH has been employed in the Egyptian National Seismic Network (ENSN) as a tool assisting with routine work and data analysis. More than 30 users have been using previous versions of SGRAPH in their research for more than 3 years. The main features of this application are ease of use, speed, small disk space requirements, and the absence of third-party developed components. Because of its architectural structure, SGRAPH can be interfaced with newly developed methods or applications in seismology. A complete setup file, including the SGRAPH package with the online user guide, is available. © 2011 Elsevier Ltd.


Yin S.,Harbin Institute of Technology | Li X.,Harbin Institute of Technology | Gao H.,Harbin Institute of Technology | Gao H.,King Abdulaziz University | Kaynak O.,Bogazici University
IEEE Transactions on Industrial Electronics | Year: 2015

This paper provides an overview of the recent developments in data-based techniques focused on modern industrial applications. As one of the hottest research topics for complicated processes, the data-based techniques have been rapidly developed over the past two decades and widely used in numerous industrial sectors nowadays. The core of data-based techniques is to take full advantage of the huge amounts of available process data, aiming to acquire the useful information within. Compared with the well-developed model-based approaches, data-based techniques provide efficient alternative solutions for different industrial issues under various operating conditions. The main objective of this paper is to review and summarize the recent achievements in data-based techniques, especially for complicated industrial applications, thus providing a referee for further study on the related topics both from academic and practical points of view. This paper begins with a brief evolutionary overview of data-based techniques in the last two decades. Then, the methodologies only based on process measurements and the model-data integrated techniques will be further introduced. The recent developments for modern industrial applications are, respectively, presented mainly from perspectives of monitoring and control. The new trends of data-based technique as well as potential application fields are finally discussed. © 2014 IEEE.


Connolly E.J.,Pennsylvania State University | Beaver K.M.,Florida State University | Beaver K.M.,King Abdulaziz University
Child Development | Year: 2015

Few studies have examined the relation between maternal caloric intake during pregnancy and growth in child academic achievement while controlling for important confounding influences. Using data from the National Longitudinal Survey of Youth, the current study examined the effects of reduced prenatal caloric intake on growth in scores on the Peabody Individual Achievement Test from ages 5 to 14. While models controlling for within-family covariates showed that prenatal caloric intake was associated with lower reading and mathematical achievement at age 5, models controlling for between-family covariates (such as maternal IQ) and unobserved familial confounders revealed only a statistically significant association between siblings differentially exposed to prenatal caloric intake and mathematical achievement at age 5. © 2015 The Society for Research in Child Development, Inc.


Juarez-Perez E.J.,Jaume I University | Sanchez R.S.,Jaume I University | Badia L.,Jaume I University | Garcia-Belmonte G.,Jaume I University | And 4 more authors.
Journal of Physical Chemistry Letters | Year: 2014

Organic-inorganic lead trihalide perovskites have emerged as an outstanding photovoltaic material that demonstrated a high 17.9% conversion efficiency of sunlight to electricity in a short time. We have found a giant dielectric constant (GDC) phenomenon in these materials consisting on a low frequency dielectric constant in the dark of the order of ε0 = 1000. We also found an unprecedented behavior in which ε0 further increases under illumination or by charge injection at applied bias. We observe that ε0 increases nearly linearly with the illumination intensity up to an additional factor 1000 under 1 sun. Measurement of a variety of samples of different morphologies, compositions, and different types of contacts shows that the GDC is an intrinsic property of MAPbX3 (MA = CH3NH3 +). We hypothesize that the large dielectric response is induced by structural fluctuations. Photoinduced carriers modify the local unit cell equilibrium and change the polarizability, assisted by the freedom of rotation of MA. The study opens a way for the understanding of a key aspect of the photovoltaic operation of high efficiency perovskite solar cells. © 2014 American Chemical Society.


Al-Abbasi F.A.,King Abdulaziz University
Medical Science Monitor | Year: 2012

Background: Acrylonitrile (ACN) is an extensively produced aliphatic nitrile. The gastrointestinal tract is an important target organ for ACN toxicity. The objective of the present study was to investigate the role of xanthine oxidase (XO) in ACN-induced gastric toxicity in rats. Material/Methods:We assessed the effect of ACN on oxidative stress parameters as xanthine oxidase (XO) and total xanthine dehydrogenase (XD)/ XO activity, superoxide anion (O 2 .-) production, reduced glutathione (GSH) levels and lipid peroxidation in gastric tissues. Results:A single oral dose of ACN (25 mg/kg) caused a significant enhancement in XO activity. ACN also caused a significant depletion of GSH levels, enhanced O 2 .- production and increased lipid peroxidation in the time-course experiment. In the dose-response experiment, ACN accelerated the conversion of XD to XO, with a significant depletion of gastric GSH in a dose-related manner. A strong negative correlation existed between the levels of GSH and the percentage enhancement in XO activity (r =-0.997). (O 2 .-) production and malondialdehyde (MDA) formation were significantly elevated in a dose-related manner. Pretreatment with allopurinol (50 mg/kg) significantly protected against ACN-induced rise in XO activity, depletion of GSH, and elevated production of (O 2 .-). However, pretreatment with diethyl maleate (DEM; 100 mg/kg) significantly aggravated the ACN-induced GSH depletion and rise in XO activity. Furthermore, DEM significantly enhanced (O 2 .-) and MDA production. Conclusions: The present study indicates that enhancement of XO activity could be implicated in ACN-induced gastric damage in rats. © Med Sci Monit.


Liu B.,Harbin Institute of Technology | Liu B.,Gordon Life Science Institute | Liu F.,Harbin Institute of Technology | Fang L.,Harbin Institute of Technology | And 3 more authors.
Bioinformatics | Year: 2015

Summary: In order to develop powerful computational predictors for identifying the biological features or attributes of DNAs, one of the most challenging problems is to find a suitable approach to effectively represent the DNA sequences. To facilitate the studies of DNAs and nucleotides, we developed a Python package called representations of DNAs (repDNA) for generating the widely used features reflecting the physicochemical properties and sequence-order effects of DNAs and nucleotides. There are three feature groups composed of 15 features. The first group calculates three nucleic acid composition features describing the local sequence information by means of kmers; the second group calculates six autocorrelation features describing the level of correlation between two oligonucleotides along a DNA sequence in terms of their specific physicochemical properties; the third group calculates six pseudo nucleotide composition features, which can be used to represent a DNA sequence with a discrete model or vector yet still keep considerable sequence-order information via the physicochemical properties of its constituent oligonucleotides. In addition, these features can be easily calculated based on both the built-in and user-defined properties via using repDNA. Availability and implementation: The repDNA Python package is freely accessible to the public at http://bioinformatics.hitsz.edu.cn/repDNA/. © 2014 The Author.


Gale P.A.,University of Southampton | Gale P.A.,King Abdulaziz University | Gale P.A.,University of Canterbury | Caltagirone C.,University of Cagliari
Chemical Society Reviews | Year: 2015

This Tutorial Review provides a short survey of anion sensing by small molecule anion receptors, molecular ensembles and chemodosimeters. The review highlights the many different mechanisms and approaches employed by supramolecular chemists for anion sensing and the wide structural variety present in these systems. This journal is © The Royal Society of Chemistry.


Mobasheri A.,University of Nottingham | Mobasheri A.,King Abdulaziz University | Shakibaei M.,Ludwig Maximilians University of Munich
Annals of the New York Academy of Sciences | Year: 2013

There are a number of pharmacological agents for the treatment of bone mineral loss and osteoporosis. Hormone replacement therapy (HRT) with estrogen is an established treatment, but it has several adverse side effects and can increase the risk of cancer, heart disease, and stroke. There is increasing interest in nutritional factors and naturally occurring phytochemical compounds with the potential for preventing age-related and postmenopausal bone loss. Resveratrol (3,5,4′-trihydroxy-trans-stilbene) is a polyphenolic phytoestrogen with osteogenic and osteoinductive properties. It can modify the metabolism of bone cells and has the capacity to modulate bone turnover. This paper provides an overview of current research on resveratrol and its effects on bone cells in vitro, highlighting the challenges and opportunities facing this area of research, especially in the context of providing nutritional support for postmenopausal women who may not benefit from HRT and older patients with various forms of arthritis, metabolic bone disease, and osteoporosis. © 2013 New York Academy of Sciences.


Many ectotherms adjust their metabolic rate seasonally in association with variations in environmental temperatures. The range and direction of these seasonal changes in reptilian metabolic rates are thought to be linked to the seasonality of activity and energy requirements. The present study was conducted to measure the standard metabolic rate (SMR) of seasonally-acclimatized Uromastyx philbyi with different body masses at 20, 25, 30, 35 and 40 °C using open-flow respirometry during the four seasons. SMR was mass-dependent. The mean exponent of mass, “b”, in the metabolism-body mass relation was 0.76 (variance=0.0007). Likewise, SMR increased as temperature increased with low Q10 values at high temperatures and high Q10 values at low temperatures. The lowest and highest Q10 values were achieved for temperature ranges of 30–35 °C for summer-acclimatized dhabbs (Q10=1.6) and 20–25 °C for winter-acclimatized dhabbs (Q10=3.9). Seasonal acclimatization effects were obvious at all temperatures (20–40 °C). Winter-acclimatized dhabbs had the lowest metabolic rates at all temperatures. The seasonal acclimatization patterns displayed by U. philbyi may represent a valuable adaptation for herbivorous desert lizards that inhabit subtropical deserts to facilitate activity during their active seasons and to conserve energy during inactivity at low temperatures. © 2016 Elsevier Ltd


Brezzi F.,Istituto Universitario Of Studi Superiori | Brezzi F.,King Abdulaziz University | Brezzi F.,CNR Institute for Applied Mathematics and Information Technologies | Marini L.D.,University of Pavia
Computer Methods in Applied Mechanics and Engineering | Year: 2013

We discuss the application of Virtual Elements to linear plate bending problems, in the Kirchhoff-Love formulation. As we shall see, in the Virtual Element environment the treatment of the C1-continuity condition is much easier than for traditional Finite Elements. The main difference consists in the fact that traditional Finite Elements, for every element K and for every given set of degrees of freedom, require the use of a space of polynomials (or piecewise polynomials for composite elements) for which the given set of degrees of freedom is unisolvent. For Virtual Elements instead we only need unisolvence for a space of smooth functions that contains a subset made of polynomials (whose degree determines the accuracy). As we shall see the non-polynomial part of our local spaces does not need to be known in detail, and therefore the construction of the local stiffness matrix is simple, and can be done for much more general geometries. © 2012 Elsevier B.V.


Al-Malki A.L.,King Abdulaziz University
Evidence-based Complementary and Alternative Medicine | Year: 2013

Oat, a rich source of soluble fiber, was considered to have a possible preventive effect on the progression of diabetic nephropathy. The present study aimed to assess this preventive activity in a rat model of diabetic nephropathy. Adult Wister rats were injected by streptozotocin (65 mg/kg). Animals were fed with normal diet or with a diet containing 20% oat (W/W) for 21 weeks. At the end of 21 weeks, all the kidney tissues were collected for various examinations. Our results suggested that oat could decrease the Scr and glucose level in blood of diabetic rats significantly (P < 0.05), and increase the creatinine clearance (P < 0.01). In histopathological examination, oat-fed rats showed a significant decrease in glomerulus segmented sclerosis and incidence of tubule vacuolar degeneration. By ELISA, we reported that oat feeding resulted in decreasing the levels of IL-6 and AGE in serum and kidney homogenate. In addition, the levels of oxidative stress markers were markedly improved as a result of oat feeding. Furthermore, using EMSA, we showed that oat attenuated the activation of NF- B. Using RT-PCR, we found that oat could downregulate the TGF- β 1 and RAGE expression at mRNA levels. This study suggests that oat can suppress diabetic nephropathy in rats effectively and may slow down the renal fibrosis by the disruption of the detrimental AGE-RAGE-NF B axis. © 2013 Abdulrahman L. Al-Malki.


Niu P.,CAS Shenyang Institute of Metal Research | Yin L.-C.,CAS Shenyang Institute of Metal Research | Yang Y.-Q.,CAS Shenyang Institute of Metal Research | Yang Y.-Q.,Hefei University of Technology | And 3 more authors.
Advanced Materials | Year: 2014

There is an inherent driving force to narrow the bandgap of photocatalysts towards this value. Introducing heteroatoms as a general strategy of tuning the bandgap of semiconductors has been attempted to narrow the bandgap of melon in order to extend its light absorption range. Compared to the intensive studies on oxygen vacancies, the underlying role of nitrogen vacancies in modulating optical and photocatalytic properties is rarely considered in developing nitride-based photocatalysts. On the other hand, the spatial distribution of dopants is recognized as an essential issue in modifying the electronic structure of photocatalysts. Homogeneous doping of appropriate heteroatoms throughout a whole particle is indispensable for effective bandgap narrowing, while surface doping can only result in some localized states in the bandgap.


Xiao S.,University of Macau | Li Y.,King Abdulaziz University | Li Y.,Tianjin University of Technology
Journal of Microelectromechanical Systems | Year: 2014

This paper presents a novel micro manipulation system based on visual servo feedback control, which is composed of a micro/nano positioning stage with large workspace, a micro gripper, and a microscope-based visual servo system. The positioning stage is featured with compliant flexure-based totally decoupled characteristics, which is driven by electromagnetic actuators. The gripper is designed with its arms moving completely parallel, which has a large displacement of gripping range. In this research, the gripper is mounted onto the micro positioning stage to form a micro-hand dedicated to micro assembly application. A microscope is adopted to observe this tiny view field and capture the information about the position of the gripping fingers and the objects. Meanwhile, a small piece of silver wire with a diameter of about 30 microns is used as the micro part. The positioning information about tips of the gripping fingers and the object can be captured via the digital microscope and processed by a novel rapid identification method. A kind of visual servo feedback tracking and gripping control algorithm is developed. The algorithm is validated through experiments by realizing the task of picking up a small piece of silver wire then placing it to a new place precisely. © 2013 IEEE.


El-Fiky A.A.,King Abdulaziz University
Journal of King Abdulaziz University, Earth Sciences | Year: 2010

The hydrogeochemical and isotopic data of groundwaters of the different aquifers of the Ras Sudr-Abu Zenima area, southwest Sinai, Egypt were examined to determine the main factors controlling the groundwater chemistry and salinity as well as its hydrogeochemical evolution. Groundwater occurs in different water-bearing formations belonging to Quaternary, Neogene, Upper Cretaceous, and Paleozoic. Different geochemical interpretation methods were used to identify the geochemical characteristics. Groundwater of the coastal Quaternary alluvial aquifer has the highest salinity values (2739-7040 mg/l) in the study area due to the impact of seawater and agricultural activities. Piper diagram showed that Cl and SO4 are the dominant anions, whereas Na is the most dominant cation, where it is sometimes replaced by Ca and/or Mg in the hydrochemical facies of the groundwaters. Durov diagram plot revealed that the groundwater has been evolved from Ca-HCO3 recharge water through mixing with the pre-existing groundwater to give mixed water of Mg-SO4 and Mg-Cl types that eventually reached a final stage of evolution represented by a Na-Cl water type. Different ionic ratios revealed the impact of seawater and marine aerosols on the hydrochemical composition of groundwater of the Quaternary aquifer. Dissolution of carbonate and sulfate minerals in the aquifer matrices and recharge areas as well as cation exchange are shown to modify the concentration of ions in groundwater. Groundwater-mineral equilibria showed the prevailing dissolution-precipitation reactions in the groundwater. The groundwaters are depleted in 2H and 18O and displayed an isotopic signature close to that of meteoric water with d-excess values indicating present-day precipitation over the region and reflect the contribution of vapour masses from Mediterranean origin. The isotopic features suggest that most of the groundwaters at the study area result from mixing between recent recharge and an older component recharged under climatic conditions cooler than at present. Moreover, groundwaters from the Cambrian and Carboniferous water-bearing formations show d-excess values of 13.9 and 10.96%, respectively, which indicates that older component of recharge is prevailing than the recent one. Isotopic signature of groundwater from the Quaternary aquifer indicated seawater contribution.


Alzahrani A.Z.,King Abdulaziz University | Srivastava G.P.,University of Exeter
Surface Science | Year: 2011

Using the pseudopotential method and the local density approximation of density functional theory we have investigated the stability, atomic geometry, and electronic states for low-coverage Ca adsorbates on the Si(001) surface within the (2 × n) reconstructions with n = 2, 3, 4, 5. Our total energy calculations suggest that the (2 × 4) phase represents the most energetically stable structure with the Ca coverage of 0.375 ML. Within this structural model, each Ca atom is found to form a bridge with the inner two Si-Si dimers. The inner Si-Si dimers become elongated and symmetric (untilted). The band structure calculation indicates that the system is semiconducting with a small band gap. Significant amount of charge transfer from the Ca atoms to neighbouring Si atoms has been concluded by analysing the electronic charge density and simulation of scanning tunnelling microscopy images. The highest occupied and lowest unoccupied electronic states are found to arise from the inner and outer Si-Si dimer components, respectively. © 2010 Elsevier B.V. All rights reserved.


Basaham A.S.,King Abdulaziz University
Journal of King Abdulaziz University, Earth Sciences | Year: 2010

The surficial sediments of the Arabian Gulf coast of Saudi Arabia are a mixture consisting mainly of calcareous material mostly of marine origin and land-derived terrigenous component with high OC (average 2.1% ±0.6). Chemical composition and the partitioning of Fe, Mn, Cu, Zn, Ni, Cr, V and Ba in operationally defined as non-residual (i.e. 1M HCl leachable) and residual fractions were determined in the <63 μm fraction of the subtidal sediments. Concentrations of metals varied widely, with no evidence for total and non-residual concentrations enrichment above the background levels in the Gulf sediments. Partitioning results showed that Fe, Cr and Ba are mainly associated with the residual component, where about 80% of their concentrations are held immobile in this fraction. For Mn, Cu, Zn, Ni and V approximately between 35 and 55 % of their concentrations are associated with the mobile non-residual fraction. Fe-Mn oxyhdroxide appears to be the main host phase for the non-residual fraction of these metals. On the other hand, carbonate materials dilute and mask the role of the major host of these metals in the sediments.


Siddiquee M.S.A.,King Abdulaziz University
Acta Geotechnica | Year: 2015

A model is proposed to simulate the stress–strain behavior of sands subjected to cyclic loads in general three-dimensional stress space. A novel formulation is developed using Prager’s kinematic hardening rule and extending the one-dimensional Masing’s rule to general three-dimensional stress space. The hysteretic stress–strain curves are constructed based on skeleton curves. In order to do this, the Masing’s rule is generalized to the proportional rule, which consists of two sets of rules: the internal and external rule. Subsequently, a drag rule is introduced to simulate cyclic stress–strain behavior in which the stress amplitude increases at a decreasing rate during cyclic loading with a constant strain amplitude. The dimensionless kinematic hardening rate is assumed to depend on the current stress value along the stress path. When the direction of loading is reversed, the initial rate of hardening is restored. The rate of variation of hardening is scaled according to an extended Masing’s law. As a result, a closed hysteretic stress–strain loop is obtained during cyclic loading. © 2015, Springer-Verlag Berlin Heidelberg.


Hawkins E.,University of Reading | Jones P.D.,University of East Anglia | Jones P.D.,King Abdulaziz University
Quarterly Journal of the Royal Meteorological Society | Year: 2013

In 1938, Guy Stewart Callendar was the first to demonstrate that the Earth's land surface was warming. Callendar also suggested that the production of carbon dioxide by the combustion of fossil fuels was responsible for much of this modern change in climate. This short note marks the 75th anniversary of Callendar's landmark study and demonstrates that his global land temperature estimates agree remarkably well with more recent analyses. © 2013 Royal Meteorological Society.


Cao S.,Wuhan University of Technology | Yu J.,Wuhan University of Technology | Yu J.,King Abdulaziz University
Journal of Physical Chemistry Letters | Year: 2014

Graphitic carbon nitride (g-C3N4)-based photocatalysts have attracted dramatically increasing interest in the area of visible-light-induced photocatalytic hydrogen generation due to the unique electronic band structure and high thermal and chemical stability of g-C 3N4. This Perspective summarizes the recent significant advances on designing high-performance g-C3N4-based photocatalysts for hydrogen generation under visible-light irradiation. The rational strategies such as nanostructure design, band gap engineering, dye sensitization, and heterojunction construction are described. Finally, this Perspective highlights the ongoing challenges and opportunities for the future development of g-C3N4-based photocatalysts in the exciting research area. © 2014 American Chemical Society.


Lu J.,Argonne National Laboratory | Li L.,Beijing Institute of Technology | Park J.-B.,Hanyang University | Sun Y.-K.,Hanyang University | And 3 more authors.
Chemical Reviews | Year: 2014

The petroleum that is used for automobile and light truck applications represents 34% of the world's total primary energy source. In the US, the transportation sector is the single greatest consumer of imported oil. In 2010, 94% of the US transportation energy was derived from petroleum, nearly half of which came from foreign sources. The carbon dioxide emissions due to the US transportation sector account for 40% of the total carbon dioxide emission, which is considered as a major cause of geopolitical instability. The US transportation sector also represents about 27% of all US GHG emissions. However, even with today's mix of fossil, nuclear, and renewable energy sources for US electric power generation, it is estimated that, on a well-to-wheel basis, an all-electric vehicle will generate 25% less GHG emissions than a conventional gasoline-powered vehicle. Even lower emissions are predicted with increased use of renewable energy sources.


Bogorodsky S.V.,Station of Naturalists | Mal A.O.,King Abdulaziz University
Journal of Natural History | Year: 2014

Species of the callionymid fish genus Diplogrammus of the Red Sea are reviewed. Four species are recognized: D. gruveli Smith, 1963 from the northern Gulf of Suez and Suez Canal; D. infulatus Smith, 1963 from the western shores of the Red Sea and the entrance of the Gulf of Aqaba; D. paucispinis n. sp. from the eastern shore of the Red Sea; D. randalli Fricke, 1983 from the Gulf of Suez and Gulf of Aqaba. Diplogrammus paucispinis n. sp. is characterized by having three or four curved spinules on the dorsal margin of the preopercular spine, first dorsal fin with a filament in males but not in females, first spine significantly longer than first ray of the second dorsal fin in males, anal fin translucent in males with outer one-third black, no bluish lines on head and body in males. A key to the species of Diplogrammus is presented; endemism of Red Sea fish species is discussed. http://www.zoobank.org/urn:lsid:zoobank.org:pub:848161AE-0E4C-456E-8743-E5E3F62AB507 © 2014, © 2014 Taylor & Francis.


Mandoorah Q.M.,King Abdulaziz University
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation, Saudi Arabia | Year: 2014

To assess the quality of life (QOL) of Saudi Arabian patients undergoing hemo-dialysis (HD) and to determine the impact of gender, age, education and comorbidities on the QOL of these patients, we conducted a cross-sectional study and used the short form-36 (SF-36) questionnaire, a generic instrument for measuring QOL. This questionnaire is composed of eight scales that summarize the physical component scale (PCS) and mental component scale (MCS) of health status. We calculated the PCS and MCS scores for each patient. We studied 205 HD patients (123 men; ages 18-75 years) from the King Fahd General Hospital, Jeddah, Saudi Arabia. The mean SF-36 score was 59.4 ± 21.7 in men and 41.9 ± 20.9 in women (P <0.0001). Patients older than 60 years had the worst score (41.5 ± 21.2), followed by patients aged 40-59 years (53.6 ± 22.8); patients aged 18-39 years had the best SF-36 score (57.5 ± 22.5; P <0.0001). Education had a positive impact on QOL (P <0.0001), whereas comorbid conditions had a negative impact. Peripheral vascular disease was associated with the worst outcome (SF-36 score, 40.4 ± 23.0; P <0.0001), followed by dyslipidemia (42.9 ± 22.4; P = 0.001) and diabetes mellitus (45.0 ± 22.0; P = 0.012). Among the comorbid conditions, hypertension was associated with the best SF-36 score (50.6 ± 22.7; P = 0.034). We conclude that old age, female gender, poor education and comorbid conditions have a negative impact on the QOL of HD patients in Saudi Arabia. These findings indicate a general need for social support for female patients on HD and early diagnosis and management of comorbid conditions.


Wong M.S.,Southwestern Medical Center | Wright W.E.,Southwestern Medical Center | Shay J.W.,King Abdulaziz University
Trends in Genetics | Year: 2014

Alternative splicing affects approximately 95% of eukaryotic genes, greatly expanding the coding capacity of complex genomes. Although our understanding of alternative splicing has increased rapidly, current knowledge of splicing regulation has largely been derived from studies of highly expressed mRNAs. Telomerase is a key example of a protein that is alternatively spliced, but it is expressed at very low levels and although it is known that misregulation of telomerase splicing is a hallmark of nearly all cancers, the details of this process are unclear. Here we review work showing that hTERT expression is in part regulated by atypical alternative splicing, perhaps due to its exceptionally low expression level. We propose that these differential regulatory mechanisms may be widely applicable to other genes and may provide new opportunities for the development of cancer therapeutics. © 2014 Elsevier Ltd. All rights reserved.


Li X.,Harbin Institute of Technology | Yin S.,Harbin Institute of Technology | Gao H.,Harbin Institute of Technology | Gao H.,King Abdulaziz University
Automatica | Year: 2014

This paper is concerned with model reduction for passive systems. For a given linear time-invariant system that is stable and positive real (PR), our goal is to find a PR reduced-order model to approximate it, and our attention is focused on reducing the error with respect to a finite frequency H∞ performance, which is the most remarkable difference between the proposed approach and the existing ones. First, by applying multiplier expansion, new conditions in terms of linear matrix inequalities are derived for characterizing the positive realness of the reduced-order model and the finite frequency H∞ performance of the error system. A necessary and sufficient condition is then established for parameterizing a PR reduced-order model with finite frequency H∞ approximation performance, based on which, an iterative algorithm is constructed for numerically exploring such a reduced-order model. Particularly, a partial multiplier expansion treatment is introduced, which greatly reduces the decision variables but does not cause conservatism to the derived conditions. The proposed method is also extended to robust passivity-reserving model reduction with polytopic uncertainty. Finally, we provide two numerical examples about RLC circuits to show the effectiveness and advantages of the proposed model reduction method. © 2014 Elsevier Ltd. All rights reserved.


Almazroui M.,King Abdulaziz University
International Journal of Climatology | Year: 2013

In this article, climate parameters (rainfall and temperature) are simulated for Saudi Arabia by downscaling the European Centre for Medium-Range Weather Forecasts (ECMWF) 40-year reanalysis (ERA40) and the European Community - Hamburg Atmospheric Model (ECHAM5) data using the UK Met Office Regional Climate Model PRECIS (Providing REgional Climates for Impacts Studies). Simulations are performed for a present climate of 30years (1971-2000) using ERA40 and ECHAM5, and future climate is predicted for a period of 50years (2021-2070) using ECHAM5 A1B emissions scenario. The results show that the spatial distribution of the present-day rainfall and temperature simulated by PRECIS are consistent with the observed dataset. In addition, their annual cycle and interannual variability are reasonably well reproduced. The dry precipitation and warm temperature biases exhibited in the driving fields (compared with the observations) are reduced because of the improvements in specific humidity and in the wind field within the PRECIS simulations compared with the driving fields. The projection using the calibrated national average temperature exhibits a positive trend in mean temperature of around 0.65°C per decade. For rainfall projection, the results show that the coastal areas along the central parts of the Red Sea and the south-southwestern areas of Saudi Arabia may experience more extreme rainfall events, whereas the northern and central parts of the country may undergo a drying trend. © 2013 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society. © 2013 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.


Baeissa E.S.,King Abdulaziz University
Journal of Industrial and Engineering Chemistry | Year: 2014

Cobalt metal was doped on TiO2-SiO2 by photo-assisted deposition (PAD) and impregnation (Img) methods. The prepared catalysts were characterized by different techniques such as XRD, XAFS, TEM, and nitrogen adsorption analysis. Photocatalytic reactivity using Co/TiO2-SiO2 catalysts under visible-light conditions on the oxidation of cyanide with O2 reaction was evaluated. The results have shown notable photocatalytic activity of PAD-Co/TiO2-SiO2 which was 1.7 and 10 times higher than that of Img-Co/TiO2-SiO2 and TiO2-SiO2, respectively. © 2014 The Korean Society of Industrial and Engineering Chemistry.


Aazam E.S.,King Abdulaziz University
Journal of Industrial and Engineering Chemistry | Year: 2014

CdS nanoparticles were prepared by a hydrothermal method, and Au was deposited onto the surface of CdS via a photoassisted deposition method. The resulting samples were characterised by X-ray diffraction, ultraviolet and visible spectroscopy, photoluminescence emission spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and surface area measurements. The catalytic performance of the samples in the photocatalytic oxidation of cyanide under visible light was determined. The UV-vis analysis indicated that a red shift occurred after Au was loaded onto CdS nanoparticles. The maximum photocatalytic oxidation efficiency was 100%, which was obtained using 0.2 wt% Au/CdS after a reaction time of 40. min. © 2013 The Korean Society of Industrial and Engineering Chemistry.


Baeissa E.,King Abdulaziz University
Journal of Industrial and Engineering Chemistry | Year: 2014

AgInS2 nanoparticles were prepared via a microwave method, while NiO was immobilized on the surface of AgInS2 via an impregnation method. The samples produced were characterized using different techniques. The catalytic performances of the AgInS2 and NiO/AgInS2 samples were carried out for photocatalytic oxidation of thiophene under visible light. The maximum oxidation efficiency achieved was 100% at 0.3 NiO/AgInS2 photocatalyst. The doping of NiO into the AgInS2 was useful in improving the photocatalytic activity. The catalyst could be reused without any loss in activity during the first five cycles. © 2013 The Korean Society of Industrial and Engineering Chemistry.


Qusti A.H.,King Abdulaziz University
Journal of Industrial and Engineering Chemistry | Year: 2014

Manganese oxide nanofibers (MONFs) were synthesized, characterized, and successfully used for the removal of the toxic Cr(VI) ions from a model and the real solution. The results showed that the MONFs were fibers, whose shape consisted of an average diameter of 10nm to 16nm and a specific surface area equal to 94.1m2g-1, that was mainly composed of crystalline α-MnO2 (i.e., as was confirmed with the XRD measurement). The effect of different parameters that affected the adsorption process was studied and optimized. The results showed an efficient removal at pH 2.0, within 60min, and by using 150mg MONFs at the ambient temperature. The adsorption of Cr(VI) ions from an aqueous solution was studied kinetically at different temperatures. The results showed that the removal process followed the pseudo-second-order model, with an adsorption capacity of 14.6mgg-1 at ambient temperature. The thermodynamic parameters were calculated and the results showed that the adsorption of Cr(VI) ions from aqueous solution by MONFs is physical, spontaneous, and exothermic (δH=-39.3kJmol-1) in nature, with negative entropy. Finally, MONFs were used for the removal of Cr(VI) ions from a real sample, and the result indicated that the MONFs are highly efficient at removing the toxic Cr(VI) ions. © 2013 The Korean Society of Industrial and Engineering Chemistry.


Michl J.,University College London | Ingrouille M.J.,University of London | Simmonds M.S.J.,University College London | Heinrich M.,University College London | Heinrich M.,King Abdulaziz University
Natural Product Reports | Year: 2014

Aristolochic acids are known for causing aristolochic acid nephropathy, a renal fibrosis often associated with urothelial carcinoma. Aristolochic acid I and II are considered to be the cause of these nephrotoxic and carcinogenic effects. However a variety of aristolochic acid analogues, including aristolactams and 4,5-dioxoaporphines have been reported. Their implications in aristolochic acid nephropathy have possibly been overlooked. In this report, in vivo and in vitro toxicity and mutagenicity of these three classes of compounds are discussed. Furthermore, the review gives an update of aristolochic acids, aristolactams and 4,5-dioxoaporphines reported between 2003 and 2013 and their biological activities. © 2014 the Partner Organisations.


Khaled A.-R.A.,King Abdulaziz University
Mathematical Problems in Engineering | Year: 2015

Heat transfer enhancement in permeable tubes subjected to transverse suction flow is investigated in this work. Both momentum and energy equations are solved analytically and numerically. Both solutions based on negligible entry regions are well matched. Two different suction velocity distributions are considered. A parametric study including the influence of the average suction velocity and the suction velocity profile is conducted for various Peclet numbers. It is found that enhancement of heat transfer over that in impermeable tubes is only possible with large Peclet numbers. This enhancement increases as suction velocities towards the tube outlet increase and as those towards the tube inlet decrease simultaneously. The identified enhancement mechanisms are expanding the entry regions, increasing the transverse advection, and increasing the downstream excess temperatures under same transverse advection. The average suction velocity that produces maximum enhancement increases as the Peclet number increases until it reaches asymptotically its uppermost value at large Peclet numbers. The maximum reported enhancement ratios for the exponential and linear suction velocity distributions are 17.62-fold and 14.67-fold above those for impermeable tubes, respectively. This work demonstrates that significant heat transfer enhancement is attainable when the suction flow inside the permeable tubes is distributed properly. © 2015 A.-R. A. Khaled.


Dadashi-Silab S.,Technical University of Istanbul | Atilla Tasdelen M.,Yalova University | Yagci Y.,Technical University of Istanbul | Yagci Y.,King Abdulaziz University
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2014

In macromolecular and material science, atom transfer radical polymerization (ATRP) has intensely influenced the research strategies facilitating fabrication of a wide range of polymers with well-defined structures and functions and their conjugation with biomolecules. Recently, the required copper (I) catalyst for ATRP process is generated by photoinduced redox reactions involving the in situ reduction of Cu(II) to Cu(I). Photochemically initiated reactions provide several distinct advantages, including temporal and spatial controls, rapid and energy efficient activation. The process is based on photoredox reactions of copper catalysts under various radiation sources with or without various photoinitiators. This Highlight focuses on the historical development, mechanistic aspects, limitations, and opportunities of photoinitiated ATRP along with selected examples. © 2014 Wiley Periodicals, Inc.


Abouelmagd E.I.,King Abdulaziz University | El-Shaboury S.M.,Ain Shams University
Astrophysics and Space Science | Year: 2012

In this paper, we study the existence of libration points and their linear stability when the three participating bodies are axisymmetric and the primaries are radiating, we found that the collinear points remain unstable, it is further seen that the triangular points are stable for 0<μ<μ c, and unstable for μ c≤ μ ≤ 1/2 where μ c∈(0,1/2), it is also observed that for these points the range of stability will decrease. In addition to this we have studied periodic orbits around these points in the range 0<μ<μ c, we found that these orbits are elliptical; the frequencies of long and short orbits of the periodic motion are affected by the terms which involve parameters that characterize the oblateness and radiation repulsive forces. The implication is that the period of long periodic orbits adjusts with the change in its frequency while the period of short periodic orbit will decrease. © 2012 Springer Science+Business Media B.V.


Kiskan B.,Technical University of Istanbul | Yagci Y.,King Abdulaziz University
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2014

In this work, a self-healing strategy for poly(propylene oxide)s bearing coumarine-benzoxazine units (PPO-CouBenz)s based on light induced coumarine dimerization reactions is described. Four different types of poly(propylene oxide) amines with molecular weights ranging from 440 to 5000 Da were reacted with formaldehyde and 4-methyl-7-hydroxycoumarin to yield desired (PPO-CouBenz)s. The crosslinked polymer films were prepared by solvent casting of various compositions of PPO-CouBenzs in chloroform followed by thermal ring opening reaction of benzoxazine groups at 210-240 C. Thermal curing and thermal stability of the initial PPOs and final products were investigated. Using allyl benzoxazine in the formulation, it was demonstrated that the toughness of the films was improved. Photoinduced healing of coumarin-based cured PPO-CouBenz polymer films was investigated. © 2014 Wiley Periodicals, Inc.


Abouelmagd E.I.,King Abdulaziz University
Astrophysics and Space Science | Year: 2012

In this paper, we prove that the locations of the triangular points and their linear stability are affected by the oblateness of the more massive primary in the planar circular restricted three-body problem, considering the effect of oblateness for J 2 and J 4. After that, we show that the triangular points are stable for 0<μ<μ c and unstable when μ c ≤ μ ≤ 1/2, where μ c is the critical mass parameter which depends on the coefficients of oblateness. On the other hand, we produce some numerical values for the positions of the triangular points, μ and μ c using planets systems in our solar system which emphasis that the range of stability will decrease; however this range sometimes is not affected by the existence of J 4 for some planets systems as in Earth-Moon, Saturn-Phoebe and Uranus-Caliban systems. © 2012 Springer Science+Business Media B.V.


Karagiaridi O.,Northwestern University | Bury W.,Northwestern University | Bury W.,Warsaw University of Technology | Mondloch J.E.,Northwestern University | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014

Metal-organic frameworks (MOFs) have gained considerable attention as hybrid materials - in part because of a multitude of potential useful applications, ranging from gas separation to catalysis and light harvesting. Unfortunately, de novo synthesis of MOFs with desirable function-property combinations is not always reliable and may suffer from vagaries such as formation of undesirable topologies, low solubility of precursors, and loss of functionality of the sensitive network components. The recently discovered synthetic approach coined solvent-assisted linker exchange (SALE) constitutes a simple to implement strategy for circumventing these setbacks; its use has already led to the generation of a variety of MOF materials previously unobtainable by direct synthesis methods. This Review provides a perspective of the achievements in MOF research that have been made possible with SALE and examines the studies that have facilitated the understanding and broadened the scope of use of this invaluable synthetic tool. Changing pillars: Solvent-assisted linker exchange (SALE) has gained a lot of attention as a novel synthetic pathway toward metal-organic frameworks (MOFs) that are challenging to access de novo. This Review analyzes the recent advances in the application of SALE and provides a critical assessment of the studies that have facilitated our understanding of this invaluable tool for the development of new MOFs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Bukhari A.,King Abdulaziz University
Middle East African Journal of Ophthalmology | Year: 2013

Aim: To determine the prevalence of various causes of tearing among patients referred to an oculoplastic clinic. Materials and Methods: A prospective study on all patients seen in an oculoplastic clinic with a chief complaint of tearing. The cause of tearing was determined on the basis of the anatomical location of the primary etiology. Results: This study included 357 patients with a mean age 53.9 years. Punctal stenosis was the most common etiology, affecting 37.8% of the patients. Among patients with punctual stenosis, 63.4% were women over 50-year-old (P = 0.001); 55.6% had tearing for less than 6 months (P = 0.038), and all of them had associated chronic blepharitis. The remaining study participants had dry eye with reflex tearing (27.7%), nasolacrimal duct obstruction (10.1%), canalicular obstruction (4.2%), entropion or ectropion (3.4%), pterygium (1.7%), megalo-caruncle (1.7%), and functional tearing (1.7%). Conclusion: The outcomes of this study indicate the most common cause of tearing is punctal pathology. Therefore, slit lamp evaluation with careful attention to the punctum is warranted in all patients with tearing.


Dai Y.,Beth Israel Deaconess Medical Center | Kamal M.A.,King Abdulaziz University
CNS and Neurological Disorders - Drug Targets | Year: 2014

The incidence of Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) with associated serious complications continues to grow rapidly especially in developed countries. Emerging evidence indicates that AD and T2DM share some common risk factors with comparable pathological features including insulin resistance, amyloidogenesis, glucocorticoid imbalance, inflammation, mitochondrial function and oxidative stress. T2DM has been identified as a risk factor for AD. It has even been hypothesized that AD might be "type 3 diabetes". In addition to amyloid precursor protein processing and tau phosphorylation, commonalities between T2DM and AD in molecular mechanisms provide clues to the identification of novel therapeutic targets such as glucagon-like peptide 1, butyrylcholinesterase, and receptor for advanced glycosylation end products. Although several classes of anti-diabetic drugs are available, achieving long-term glycaemic control without side effects is often challenging. This review summarizes recent evidence for the pathological links, common therapeutic targets, currently the U.S. Food and Drug Administration approved and potential future therapies, giving special attention to ongoing clinical trials of antidiabetic drugs in AD patients and common therapeutic strategies in the management of both AD and T2DM. © 2014 Bentham Science Publishers.


Che L.,Illinois Institute of Technology | Shahidehpour M.,Illinois Institute of Technology | Shahidehpour M.,King Abdulaziz University
IEEE Transactions on Smart Grid | Year: 2014

The additional deployment of distributed energy resources (DERs) has attracted further attention to dc microgrid applications. The objective of the study is to discuss the possibilities and the merits of adopting a dc control system for enhancing the economics and the resilient operation of a dc microgrid, and to test the proposed hierarchical control strategy that applies to a dc microgrid. This paper provides case studies in which an existing microgrid at the Illinois Institute of Technology (IIT) is operated as a dc microgrid and the results for each case are compared with the ac model. The structure, components, and control strategies of IIT dc microgrids are discussed and the economic operation of a grid-connected dc microgrid through tertiary control, as well as islanding, load restoration, and resynchronization of the dc microgrid are simulated. The dc microgrid simulation results are compared with those of an ac microgrid, which demonstrate that the proposed coordinated dc strategy for the optimal operation of DERs is an effective way of ensuring the resilient response of dc microgrid to emergencies and its economic operation at steady state. © 2014 IEEE.


Awan Z.,King Abdulaziz University | Genest J.,McGill University
European Journal of Preventive Cardiology | Year: 2015

Heart disease and stroke represent the major burden of health worldwide and account for a staggering 17 million deaths yearly. This pandemic is, in great part preventable through simple and modifiable preventive measures such as smoking cessation, healthy eating, regular activity and weight loss. In patients with established atherosclerotic vascular disease, lipid lowering agent have had a major impact on reducing risk, along with pharmacological treatment of elevated blood pressure and the use of anti-thrombotic medication. Despite these advances, there remains a significant residual risk and newer approaches are required to decrease atherosclerosis. Innate and acquired immunity play a pivotal role in the initiation, progression and instability of the atherosclerotic plaque. The remarkable complexity of the immune system makes it difficult to target a single pathway for the prevention of cardiovascular disease. Nevertheless, recent data points to possible therapeutic targets that may decrease atherosclerosis, without increasing the risk of infection, decreasing immune surveillance for cancers and without undue toxicity. Here we discuss the clinical trials and registry data associated with the use of inflammation modulation and cardiovascular disease and the ongoing major clinical trial that may change the clinical medicine and preventive cardiology. The selective inhibition of interleukin 1β and the use of low-dose methotrexate are now undergoing large outcome-driven clinical trials to answer these questions. © 2014 The European Society of Cardiology.


Khaled A.-R.A.,King Abdulaziz University
Journal of Heat Transfer | Year: 2010

Heat transfer through rectangular permeable fins is modeled and analyzed theoretically in this work. The free stream fluid flow is considered to be normal to the upper surface of the permeable fin. The flow across the permeable fin is permitted in this work. The continuity, momentum, and energy equations are solved for the fluid flow using a similarity transformation and an iterative tridiagonal finite difference method. As such, a correlation for the Nusselt number is generated as functions of the Prandtl number (Pr) and dimensionless suction velocity (fo) for 0.7


Sayegh F.A.Q.,King Abdulaziz University | Montagnes D.J.S.,University of Liverpool
Bioresource Technology | Year: 2011

Three Isochrysis galbana strains, one I. galbana "substrain" , and one Nannochloropsis sp. strain were grown in nutrient replete conditions at 15, 20, 25, and 30. °C. The interactive effect of temperature and isolate on growth rate, cell volume, production, dry weight, protein content, carbohydrate content, and total lipid content was examined. Nannochloropsis sp., growth rate had no relation with temperature; all I. galbana isolates increased linearly with temperature, with no significant differences. Cell volume and dry weight decreased linearly with temperature, with significant isolate and species differences. Biovolume-production did not vary significantly with temperature, but significant isolate and species differences occurred. Although significant temperature isolate interactions existed, no consistent trends in the change of protein, carbohydrate, and lipid with temperature occurred. We indicate a need to consider temperature induced affects in application using microalgae isolates, at various taxonomic levels, as some intraspecific differences were as great as interspecific differences. © 2010 Elsevier Ltd.


To assess the potential health risks associated with indoor radon, a study was carried out in 80 dwellings in Jeddah city, Saudi Arabia using CR-39 plastic track detectors. The annual average indoor radon concentrations varied from 21 to 52 Bq m3, with a mean value of 36 Bq m3, which is well below the recommended action level recommended by the International Commission on Radiological Protection (ICRP). The annual effective dose varied from 0.35 to 0.89 mSv y1. The results showed no significant radiological risks for the inhabitants. The radium content, radon exhalation rate and the concentration of radon in soils samples were measured using the 'Can Technique'. The radium concentrations in soil varied from 18.0 to 33.0 Bq kg1. The radon exhalation rates in the samples varied from 4.58 to 8.40 Bq m2 h1 (135 to 251 mBq kg1 h1). There was a linear relationship between the indoor radon concentration and the radium concentration in the soil. A positive correlation was observed between the radon exhalation rate and soil radium concentration. Furthermore, changes in the ventilation rate had a significant effect on the indoor radon concentration. © International Society of the Built Environment. © The Author(s) 2014.


Rottig A.,University of Munster | Steinbuchel A.,University of Munster | Steinbuchel A.,King Abdulaziz University
Microbiology and Molecular Biology Reviews | Year: 2013

Long-chain-length hydrophobic acyl residues play a vital role in a multitude of essential biological structures and processes. They build the inner hydrophobic layers of biological membranes, are converted to intracellular storage compounds, and are used to modify protein properties or function as membrane anchors, to name only a few functions. Acyl thioesters are transferred by acyltransferases or transacylases to a variety of different substrates or are polymerized to lipophilic storage compounds. Lipases represent another important enzyme class dealing with fatty acyl chains; however, they cannot be regarded as acyltransferases in the strict sense. This review provides a detailed survey of the wide spectrum of bacterial acyltransferases and compares different enzyme families in regard to their catalytic mechanisms. On the basis of their studied or assumed mechanisms, most of the acyl-transferring enzymes can be divided into two groups. The majority of enzymes discussed in this review employ a conserved acyltransferase motif with an invariant histidine residue, followed by an acidic amino acid residue, and their catalytic mechanism is characterized by a noncovalent transition state. In contrast to that, lipases rely on completely different mechanism which employs a catalytic triad and functions via the formation of covalent intermediates. This is, for example, similar to the mechanism which has been suggested for polyester synthases. Consequently, although the presented enzyme types neither share homology nor have a common three-dimensional structure, and although they deal with greatly varying molecule structures, this variety is not reflected in their mechanisms, all of which rely on a catalytically active histidine residue. Copyright © 2013, American Society for Microbiology. All Rights Reserved.


Trilling A.K.,Plant Research International | Trilling A.K.,Wageningen University | Beekwilder J.,Plant Research International | Zuilhof H.,Wageningen University | Zuilhof H.,King Abdulaziz University
Analyst | Year: 2013

Detection elements play a key role in analyte recognition in biosensors. Therefore, detection elements with high analyte specificity and binding strength are required. While antibodies (Abs) have been increasingly used as detection elements in biosensors, a key challenge remains-the immobilization on the biosensor surface. This minireview highlights recent approaches to immobilize and study Abs on surfaces. We first introduce Ab species used as detection elements, and discuss techniques recently used to elucidate Ab orientation by determination of layer thickness or surface topology. Then, several immobilization methods will be presented: non-covalent and covalent surface attachment, yielding oriented or random coupled Abs. Finally, protein modification methods applicable for oriented Ab immobilization are reviewed with an eye to future application. This journal is © The Royal Society of Chemistry.


Al-sieni A.I.,King Abdulaziz University
African journal of traditional, complementary, and alternative medicines : AJTCAM / African Networks on Ethnomedicines | Year: 2014

Nowadays there is a need to find naturally occurring substances from plants with antimicrobial activity as an alternative to available used antibiotics. Salvadora persica (miswak) and Commiphora gileadensis were collected, dried and extracted with either methanol or warm water and the obtained extracts were assessed for their antibacterial activity against 5 different genera of bacteria using agar well diffusion method. The tested bacteria included some human pathogens. The obtained extracts exhibited considerable inhibitory effects against all the tested bacteria with various degrees of growth inhibition. It was shown that methanol extract was more effective compared to water extracts. The minimum inhibitory concentrations (MIC) of the methanol extracts ranged from 50-100 °g/ml. No toxicity was found using Artimia salina as test organism and no antitumor activity against Ehrlich ascites carcinoma. S. persica and C. gileadensis showed moderate to high inhibitory activity on pathogenic bacteria with no toxicity and can be used traditionally as alternative medicine.


Azpiroz J.M.,CNR Institute of Neuroscience | Azpiroz J.M.,Donostia International Physics Center | Mosconi E.,CNR Institute of Neuroscience | Bisquert J.,Jaume I University | And 2 more authors.
Energy and Environmental Science | Year: 2015

In spite of the unprecedented advance of organohalide lead perovskites in the photovoltaics scenario, many of the characteristics of this class of materials, including their slow photoconductivity response, solar cell hysteresis, and switchable photocurrent, remain poorly understood. Many experimental hints point to defect migration as a plausible mechanism underlying these anomalous properties. By means of state-of-the-art first-principles computational analyses carried out on the tetragonal MAPbI3 (MA = methylammonium) perovskite and on its interface with TiO2, we demonstrate that iodine vacancies and interstitials may easily diffuse across the perovskite crystal, with migration activation energies as low as ∼0.1 eV. Under working conditions, iodine-related defects are predicted to migrate at the electrodes on very short time scales (<1 μs). MA and Pb vacancies, with calculated activation barriers of ∼0.5 and 0.8 eV, respectively, could be responsible for the slow response inherent to perovskites, with typical calculated migration times of the order of tens of ms to minutes. By investigating realistic models of the perovskite/TiO2 interface we show that negatively charged defects, e.g. MA vacancies, close to the electron transport layer (TiO2 in our case) modify the perovskite electronic state landscape, hampering charge extraction at selective contacts, thus possibly contributing to the observed solar cell hysteresis. We further demonstrate the role of the electron transport layer in affecting the initial concentration of defects close to the selective contacts, highlighting how charge separation at the perovskite/TiO2 interface may further change the defect distribution. We believe that this work, identifying the mobile species in perovskite solar cells, their migration across the perovskite material, and their effect on the operational mechanism of the device, may pave the way for the development of new materials and solar cell architectures with improved and stabilized efficiencies. © 2015 The Royal Society of Chemistry.


Bhrawy A.H.,King Abdulaziz University | Bhrawy A.H.,Beni Suef University | Zaky M.A.,National Research Center of Egypt
Nonlinear Dynamics | Year: 2015

The cable equation plays a central role in many areas of electrophysiology and in modeling neuronal dynamics. This paper reports an accurate spectral collocation method for solving one- and two-dimensional variable-order fractional nonlinear cable equations. The proposed method is based on shifted Jacobi collocation procedure in conjunction with the shifted Jacobi operational matrix for variable-order fractional derivatives, described in the sense of Caputo. The main advantage of the proposed method is to investigate a global approximation for spatial and temporal discretizations. In addition, the method reduces the variable-order fractional nonlinear cable equation to a simpler problem that consists of solving a system of algebraic equations. The validity and effectiveness of the method are demonstrated by solving three numerical examples. The convergence of the method is graphically analyzed. The results demonstrate that the proposed method is a powerful algorithm with high accuracy for solving the variable-order nonlinear partial differential equations. © 2014, Springer Science+Business Media Dordrecht.


Khaled A.-R.A.,King Abdulaziz University
Journal of Heat Transfer | Year: 2010

This work considers heat transfer in fin-thin film systems. Two types of these systems are analyzed: (A) a thin film sandwiched between two identical fin halves, and (B) a fin sandwiched between two identical thin films. The corresponding coupled energy equations are solved numerically by an implicit, iterative, finitedifference scheme. Comparisons with derived approximate closedform solutions are performed and good agreement is obtained. A parametric study of all involved parameters is conducted and presented graphically. Useful correlations containing the various physical parameters for both types are reported. It is found that thermal efficiencies of fins can be increased significantly by introducing an internal flow inside the fin material. Moreover, factors producing more internal convections are found to increase the fin-thin film thermal efficiency. In addition, thermal efficiencies of type A systems are found to be higher than those of type B systems. Moreover, the resulting system thermal efficiency is found to have at most one local maximum and one local minimum over the whole relative heights ratio spectrum. Finally, this work paves a way for an effective combined passive and active method for enhancing heat transfer. Copyright © 2010 by ASME.


Liu X.,University of California at Santa Barbara | Sun Y.,University of California at Santa Barbara | Hsu B.B.Y.,University of California at Santa Barbara | Lorbach A.,University of California at Santa Barbara | And 5 more authors.
Journal of the American Chemical Society | Year: 2014

Increases in the molecular length of narrow band gap conjugated chromophores reveal potentially beneficial optical and electronic properties, thermal stabilities, and high power conversion efficiencies when integrated into optoelectronic devices, such as bulk heterojunction organic solar cells. With the objective of providing useful information for understanding the transition from small-sized molecules to polymers, as well as providing a general chemical design platform for extracting relationships between molecular structure and bulk properties, we set out to vary the electron affinity of the molecular backbone. Therefore, a series of donor (D)-acceptor (A) alternating narrow band gap conjugated chromophores were synthesized based on the general molecular frameworks: D1-A1-D2-A2-D 2-A1-D1 and D1-A1-D 2-A2-D2-A2-D2-A 1-D1. When the central electron-accepting moiety (A 2) was varied or modified, two classes of molecules could be compared. First, we showed that the alteration of one single electron-accepting group, while maintaining the shape of the molecular framework, can effectively impact the optical properties and energy levels of the molecules. DFT ground state structure optimizations show similar "U" shape conformations among these molecules. Second, we examined how the site-specific introduction of fluorine atom(s) modifies the thermal properties in the solid state, while maintaining relatively similar optical and electrochemical features of interest. Structure-property relationship of such molecular systems could be rationally evaluated in the aspects of thermal-responsive molecular organizations in the solid state and dipole moments both in the ground and excited states. The impact of molecular structure on charge carrier mobilities in field effect transistors and the performance of photovoltaic devices were also studied. © 2014 American Chemical Society.


Ansari S.A.,King Abdulaziz University | Satar R.,Ibn Sina National College for Medical Studies
Journal of Molecular Catalysis B: Enzymatic | Year: 2012

The present review deals with current developments of novel β-galactosidases derived from recombinant vectors and by protein engineering approaches together with the use of efficient recombinant microbial production systems in order to present the applications of recombinant enzymes as a relevant synthetic tool in biotechnology. The union of specific physical and chemical properties of recombinant proteins with specific recognition of catalytic properties of biomolecules has led to their appearance in myriad novel biotechnological applications. The interest in exploiting recombinant enzymes as biocatalysts is constantly increasing nowadays. The plausible advantages involved with their use include their (1) rigidity and permeability, (2) hydrophobic/hydrophilic character, (3) ease of purification and large-scale production, (4) immediate separation from the reaction mixture after completion of reaction without using any chemicals or heating, (5) regenerability as they impart stability to enzymes by protecting their active sites from deactivation, and (6) recombinant enzymes can be conveniently tailored within utility limits. β-Galactosidase is one of the relatively few enzymes that have been used in large-scale processes to perform lactose hydrolysis and galacto-oligosaccharide production. Thus, the present article gives brief outline of recombinant β-galactosidases obtained from various mesophilic, psychrophilic and thermophilic sources and their potential applications in biotechnology industry. © 2012 Elsevier B.V. All rights reserved.


Elsayed E.M.,King Abdulaziz University | Elsayed E.M.,Mansoura University
Nonlinear Dynamics | Year: 2015

This paper aims to develop a new method to obtain periodic solutions with period two and three of the following recursive sequence (Formula presented.) where the parameters α, β and γ are positive real numbers and the initial conditions x-1, x0 are positive real numbers. Also, it investigates the global convergence and boundedness of the aforementioned equation. © 2014, Springer Science+Business Media Dordrecht.


Khabaz M.N.,King Abdulaziz University
Asian Pacific journal of cancer prevention : APJCP | Year: 2014

In Saudi Arabia, cancer of breast is ranked the most frequent neoplasm and second source of cancer death in the female population. Breast cancer (BC) fast diagnosis, prognosis and medication management necessitate, these days, immunohistochemistry (IHC) assessment of hormone receptors and HER2 expression profile. The present report defines the IHC profile of ER, PR and HER2 in Saudi female breast neoplasms of ductal and lobular types and associations ER, PR and HER2 expression patterns with various clinicopathological factors (age, type of tumor, size, laterality, histological grade, and involvement of axillaries lymph nodes). Ninety nine cases of breast tumors were recruited from the pathology department archive of King Abdulaziz University Hospital, Kingdom of Saudi Arabia. ER, PR and HER2 expression was assessed using IHC staining. Ductal carcinomas with a variety of histological grades constituted 88 (88.8%) of total cases. Seventy four (77.8%), 59 (62.1%), and 35 (36.8%) of ductal carcinomas showed positive staining for ER, PR and HER2, in that order. Remaining breast cancer cases were four (4%) lobular carcinomas and two (2%) mixed form of ductal and lobular types, which were ER+, PR+, and HER2-. Breast cancer expression pattern of ER, PR and HER2 in Saudi female is different from that of Tunisian and Jordanian female populations and closer to the expression pattern of Egyptian, Lebanese, Iraqi and western country females. Furthermore, the present study found two IHC patterns of breast cancer ER+/PR-/HER2+ (5%) and ER+/PR-/HER2- (11.1%), which had not been reported in other Arabic studies. Thus the rates of IHC expression patterns in breast cancer show some variation among Arabic female populations.


Aazam E.S.,King Abdulaziz University
Journal of Industrial and Engineering Chemistry | Year: 2014

AgInS2 nanoparticles were prepared by a microwave method, while Pt was doped on the surface of AgInS2 via photoassisted deposition method. The catalytic performances of the AgInS2 and Pt/AgInS2 samples were carried out for photocatalytic oxidation of cyanide under visible light. The UV-vis analysis proved a red shift was detected after the loading of Pt into the AgInS2. The maximum oxidation efficiency achieved was 100% at 1.5wt% Pt/AgInS2 photocatalyst after 35min reaction time. The catalyst could be reused without any loss in activity during the first five cycles. © 2014 The Korean Society of Industrial and Engineering Chemistry.


Hugon P.,Aix - Marseille University | Dufour J.-C.,Assistance Publique des Hopitaux de Marseille | Dufour J.-C.,Aix - Marseille University | Colson P.,Aix - Marseille University | And 4 more authors.
The Lancet Infectious Diseases | Year: 2015

The compilation of the complete prokaryotic repertoire associated with human beings as commensals or pathogens is a major goal for the scientific and medical community. The use of bacterial culture techniques remains a crucial step to describe new prokaryotic species. The large number of officially acknowledged bacterial species described since 1980 and the recent increase in the number of recognised pathogenic species have highlighted the absence of an exhaustive compilation of species isolated in human beings. By means of a thorough investigation of several large culture databases and a search of the scientific literature, we built an online database containing all human-associated prokaryotic species described, whether or not they had been validated and have standing in nomenclature. We list 2172 species that have been isolated in human beings. They were classified in 12 different phyla, mostly in the Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes phyla. Our online database is useful for both clinicians and microbiologists and forms part of the Human Microbiome Project, which aims to characterise the whole human microbiota and help improve our understanding of the human predisposition and susceptibility to infectious agents. © 2015 Elsevier Ltd.


Khabaz M.N.,King Abdulaziz University
Polish Journal of Pathology | Year: 2014

Breast carcinoma is the most common cancer and cause of death among females worldwide, including Jordan. The risk factors for breast carcinoma are linked to DNA mutation and failure of DNA repair or detoxification systems. Identification of susceptibility factors that predispose individuals to breast carcinoma if they are exposed to particular environmental agents might give further insight into the etiology of this malignancy. The glutathione S-transferase (GST) enzyme family detoxifies carcinogenic compounds. Several genes that code for these enzymes are polymorphic, with particular genotypes previously shown to confer an increased carcinoma risk. The present study investigates GST-pi polymorphism in 100-tissue samples previously diagnosed as breast carcinoma, and in 48 non-cancer age-matched breast tissues, using the restriction fragment length polymorphism (RFLP) method for the polymerase chain reaction (PCR) product. Among breast cancer cases, 58%, 40% and 2% were homozygous (Ile/Ile), heterozygous (Ile/Val) and homozygous (Val/Val) respectively. In the control group, 58%, 37.5% and 4.2% were homozygous (Ile/Ile), heterozygous (Ile/Val), and homozygous (Val/Val) respectively. Our results did not support the involvement of GST-pi gene polymorphism in susceptibility to breast carcinoma in the tested North Jordanian female population.


Daqrouq K.,King Abdulaziz University | Tutunji T.A.,Philadelphia University
Applied Soft Computing Journal | Year: 2015

This paper proposes a new method for speaker feature extraction based on Formants, Wavelet Entropy and Neural Networks denoted as FWENN. In the first stage, five formants and seven Shannon entropy wavelet packet are extracted from the speakers' signals as the speaker feature vector. In the second stage, these 12 feature extraction coefficients are used as inputs to feed-forward neural networks. Probabilistic neural network is also proposed for comparison. In contrast to conventional speaker recognition methods that extract features from sentences (or words), the proposed method extracts the features from vowels. Advantages of using vowels include the ability to recognize speakers when only partially-recorded words are available. This may be useful for deaf-mute persons or when the recordings are damaged. Experimental results show that the proposed method succeeds in the speaker verification and identification tasks with high classification rate. This is accomplished with minimum amount of information, using only 12 coefficient features (i.e. vector length) and only one vowel signal, which is the major contribution of this work. The results are further compared to well-known classical algorithms for speaker recognition and are found to be superior. © 2014 Elsevier B.V. All rights reserved.


Abdi M.N.,University of Sfax | Khemakhem M.,King Abdulaziz University
Pattern Recognition | Year: 2015

Rapid movement generation models are described in the literature as an efficient tool to apprehend the handwriting behavior. Fields of application are diverse, including handwriting description, regeneration, and more recently OCR. In this paper, we propose a grapheme-based approach to offline Arabic writer identification and verification. Rather than extracting naturel graphemes from a training corpus using segmentation and clustering, it synthesizes its own graphemes based on the beta-elliptic model. Originality lies in the independence of the grapheme codebook from any training process, and the use of a model instead. One full and four partial codebooks are generated and tested. Using feature selection, raw codebooks are reduced in size with respect to FDR, FDR and cross-correlation, and random subsampling criteria. A total of 60 feature vectors are extracted using template matching, and evaluated with 411 individual writers from the IFN/ENIT database. The results presented in this study demonstrated the wide representativity and the good generalization capability of synthetic codebooks. We obtained a top1 rate=90.02% and a top5 rate=96.35% for writer identification, and an EER=2.1% for writer verification. Our approach showed better properties than most of the surveyed techniques in terms of supported corpus size and identification rates. To the best of our knowledge, this study is among the first to exploit the concept of model-based synthetic codebooks in writer identification and verification. © 2014 Elsevier Ltd. All rights reserved.


Satola B.,University of Munster | Wubbeler J.H.,University of Munster | Steinbuchel A.,University of Munster | Steinbuchel A.,King Abdulaziz University
Applied Microbiology and Biotechnology | Year: 2013

This review outlines information about the Gram-negative, aerobic bacterium Variovorax paradoxus. The genomes of these species have G+C contents of 66.5-69.4 mol%, and the cells form yellow colonies. Some strains of V. paradoxus are facultative lithoautotrophic, others are chemoorganotrophic. Many of them are associated with important catabolic processes including the degradation of toxic and/or complex chemical compounds. The degradation pathways or other skills related to the following compounds, respectively, are described in this review: sulfolane, 3-sulfolene, 2-mercaptosuccinic acid, 3,3′- thiodipropionic acid, aromatic sulfonates, alkanesulfonates, amino acids and other sulfur sources, polychlorinated biphenyls, dimethyl terephthalate, linuron, 2,4-dinitrotoluene, homovanillate, veratraldehyde, 2,4- dichlorophenoxyacetic acid, anthracene, poly(3-hydroxybutyrate), chitin, cellulose, humic acids, metal-EDTA complexes, yttrium, rare earth elements, As(III), trichloroethylene, capsaicin, 3-nitrotyrosine, acyl-homoserine lactones, 1-aminocyclopropane-1-carboxylate, methyl tert-butyl ether, geosmin, and 2-methylisoborneol. Strains of V. paradoxus are also engaged in mutually beneficial interactions with other plant and bacterial species in various ecosystems. This species comprises probably promising strains for bioremediation and other biotechnical applications. Lately, the complete genomes of strains S110 and EPS have been sequenced for further investigations. © 2012 Springer-Verlag Berlin Heidelberg.


Aly H.A.A.,Al - Azhar University of Egypt | Aly H.A.A.,King Abdulaziz University
Journal of Immunological Methods | Year: 2012

Cancer remains one of the leading causes of death worldwide, both in developed and in developing nations. It may affect people at all ages, even fetuses, but the risk for most varieties increases with age. Current therapeutic approaches which include surgery, chemotherapy and radiotherapy are associated with adverse side effects arising from lack of specificity for tumors.The goal of any therapeutic strategy is to impact on the target tumor cells with limited detrimental effect to normal cell function. Immunotherapy is cancer specific and can target the disease with minimal impact on normal tissues. Cancer vaccines are capable of generating an active tumor-specific immune response and serve as an ideal treatment due to their specificity for tumor cells and long lasting immunological memory that may safeguard against recurrences. Cancer vaccines are designed to either prevent (prophylactic) or treat established cancer (therapeutic). Identification of tumor-associated antigens (TAAs) and tumor-specific antigens (TSAs) has led to increased efforts to develop vaccination strategies.Vaccines may be composed of whole cells or cell extracts, genetically modified tumor cells to express costimulatory molecules, dendritic cells (DCs) loaded with TAAs, immunization with soluble proteins or synthetic peptides, recombinant viruses or bacteria encoding tumor-associated antigens, and plasmid DNA encoding TSAs or TAAs in conjunction with appropriate immunomodulators. All of these antitumor vaccination approaches aim to induce specific immunological responses and localized to TAAs, destroying tumor cells alone and leaving the vast majority of other healthy cells of the body untouched. © 2012.


Shastry V.V.,Indian Institute of Science | Ramamurty U.,Indian Institute of Science | Ramamurty U.,King Abdulaziz University
Acta Materialia | Year: 2013

The nanoindentation technique can be employed in shape memory alloys (SMAs) to discern the transformation temperatures as well as to characterize their mechanical behavior. In this paper, we use it with simultaneous measurements of the mechanical and the electrical contact resistances (ECR) at room temperature to probe two SMAs: austenite (RTA) and martensite (RTM). Two different types of indenter tips-Berkovich and spherical-are employed to examine the SMAs' indentation responses as a function of the representative strain, εR. In Berkovich indentation, because of the sharp nature of the tip, and in consequence the high levels of strain imposed, discerning the two SMAs on the basis of the indentation response alone is difficult. In the case of the spherical tip, εR is systematically varied and its effect on the depth recovery ratio, ηd, is examined. Results indicate that RTA has higher ηd than RTM, but the difference decreases with increasing εR such that ηd values for both the alloys would be similar in the fully plastic regime. The experimental trends in ηd vs. εR for both the alloys could be described well with a ηd ∞ (εR)-1 type equation, which is developed on the basis of a phenomenological model. This fit, in turn, directs us to the maximum εR, below which plasticity underneath the indenter would not mask the differences in the two SMAs. It was demonstrated that the ECR measurements complement the mechanical measurements in demarcating the reverse transformation from martensite to austenite during unloading of RTA, wherein a marked increase in the voltage was noted. A correlation between recovery due to reverse transformation during unloading and increase in voltage (and hence the electrical resistance) was found. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Ahmed Z.,King Abdulaziz University
Journal of Environmental Science and Technology | Year: 2012

During last decade, researches on membrane bioreactors have been focused on nutrient removal. Different aspects of nutrient removal have been studied including different configuration of nutrient removal systems including configuration of nutrient removal systems, hybrid systems, treatment of industrial waste water, influence of hydraulic and solid retention time and dynamics of microbial community structure. A significant number of studies have been focused on microbial communities responsible for enhance nutrient removal in MBR systems. The researchers have applied numerous cultural-independent technologies in last decade. They utilized Fluorescent In Situ Hybridization (FISH), Denaturing Gradient Gel Electrophoresis (DGGE), Phospholipid Fatty Acid (PLFA) analysis and Respiratory quinone profile methods. The impacts of operational conditions such as internal recycling rate, SRT and composition of organic substrate on microbial communities have also studied. Present review summarizes important findings of studies focused on microbial communities in nutrient-removing MBR systems. © 2012 Asian Network for Scientific Information.


Zhou X.,Friedrich - Alexander - University, Erlangen - Nuremberg | Nguyen N.T.,Friedrich - Alexander - University, Erlangen - Nuremberg | Ozkan S.,Friedrich - Alexander - University, Erlangen - Nuremberg | Schmuki P.,Friedrich - Alexander - University, Erlangen - Nuremberg | Schmuki P.,King Abdulaziz University
Electrochemistry Communications | Year: 2014

The present review gives an overview of the highlights of more than 10 years of research on synthesis and applications of ordered oxide structures (nanotube layers, hexagonal pore arrangements) that are formed by self-organizing anodization of metals. In particular we address the questions after the critical factors that lead to the spectacular self-ordering during the growth of anodic oxides that finally yield morphologies such as highly ordered TiO2 nanotube arrays and similar structures. Why are tubes and pores formed - what are the key parameters controlling these processes? © 2014 Elsevier B.V.


Objective: To compare the safety and efficacy of limbal-conjunctival vs conjunctival autograft transplant for treating recurrent pterygia. Methods: In a randomized, prospective, parallel-group clinical trial, 224 patients with advanced recurrent pterygia underwent free conjunctival autograft transplant (112 eyes) or limbal-conjunctival autograft transplant (112 eyes). Two hundred five patients completed the follow-up (100 eyes from the conjunctival autograft group and 105 eyes from the limbal-conjunctival autograft group). Main Outcome Measures: Recurrence of pterygium, with complications as the secondary outcome measure (ie, signs of limbal stem cell deficiency). Results: With a mean follow-up of 62 (range, 36-96) months, 10 patients (10.0%) in the conjunctival autograft group and 1 patient (1.0%) in the limbal-conjunctival autograft group developed recurrence. No signs of limbal stem cell deficiency were observed during follow-up. Conclusion: Limbal-conjunctival transplant is safe and more effective than free conjunctival transplant in preventing recurrence after excision of recurrent pterygia (P =.004). Application to Clinical Practice: Limbal-conjunctival autografts could be a favored option for managing advanced recurrent pterygia in young high-risk patients. ©2013 American Medical Association. All rights reserved.


Ramli M.A.M.,King Abdulaziz University | Twaha S.,Skyline Technical Services Ltd.
Renewable and Sustainable Energy Reviews | Year: 2015

In this paper, an analysis of renewable energy feed-in tariffs (REFIT) for the selected regions of the globe is done with the aim of drawing lesson for Saudi Arabia. A brief background and status of renewable energy sources (RES) utilization in Saudi Arabia is given at the beginning of this paper, followed by a review of the feed-in tariff (FIT) design models reported in literature. The application of the policy in Europe, the United States, Australia, Asia and Africa is then reviewed. Some observations from the analysis of the FIT application in different countries have been discussed and finally, lessons have been drawn from the study. Some policy recommendations have been given for Saudi Arabia. The analysis of the lessons identified shows that the application of FIT scheme in Saudi Arabia is likely to speed up the development of renewable energy resources within the area. © 2015 Elsevier Ltd. All rights reserved.


Kokandi A.,King Abdulaziz University
Dermatology Research and Practice | Year: 2010

Acne is a common disease especially among teenagers. It has a considerable psychological impact on affected individuals. The aim of this paper was to assess if the effect of acne on acne-related quality of life is correlated to acne clinical severity. 112 university female students attending the university medical clinics with acne complaints were examined. Cardiff Acne Disability Index (CADI) was used to assess acne-related quality of life, and global acne grading system (GAGS) was used to assess clinical severity of acne. There was no correlation between acne severity (GAGS scoring system) and quality of life impairment as assessed by CADI score (r = 0.145, P =.127). Additionally, CADI score did not correlate with disease duration or age of patients. We therefore conclude that acne clinical severity alone does not affect acne-related quality of life changes. Many other factors might play a role. © 2010 Amal Kokandi.


The synthesis of two novel series of 1-(4-chlorophenyl)-4-hydroxy-1H-pyrazoles linked to either polysubstituted 1H-pyrazole counterparts through a carbonyl bridge, or to some biologically-active nitrogenous heterocycles by an amide linker, is described. Ten of the newly synthesized compounds were selected by the National Cancer Institute (NCI) in vitro disease-oriented antitumor screening to be evaluated for their antitumor activity. The most active six compounds 2, 3, 6, 7, 13 and 14 revealed a significant broad spectrum of antitumor potential against most of the tested subpanel tumor cell lines at the GI50 and TGI levels, together with a mild cytotoxic (LC50) activity. The pyrazolinedione analog 7 displayed remarkable growth inhibition and cytostatic effects (GI50 and TGI MG-MID values 0.67 and 53.8 μM, respectively). Compounds 13 (GI50, TGI, and LC50 MG-MID values 0.08, 30.9 and 93.3 μM) and 14 (GI50, TGI, and LC50 MG-MID values 0.36, 8.78 and 69.3 μM, respectively) proved to be the most active antitumor members identified in this study. © 2010 Elsevier Ltd. All rights reserved.


Optical wireless systems are promising candidates for next-generation indoor communication networks. Optical wireless technology offers freedom from spectrum regulations and, compared to current radio-frequency networks, higher data rates and increased security. This paper presents a fast adaptation method for multibeam angle and delay adaptation systems and a new spot-diffusing geometry, and also considers restrictions needed for complying with eye safety regulations. The fast adaptation algorithm reduces the computational load required to reconfigure the transmitter in the case of transmitter and/or receiver mobility. The beam clustering approach enables the transmitter to assign power to spots within the pixel's field of view (FOV) and increases the number of such spots. Thus, if the power per spot is restricted to comply with eye safety standards, the new approach, in which more spots are visible within the FOV of the pixel, leads to enhanced signal-to-noise ratio (SNR). Simulation results demonstrate that the techniques proposed in this paper lead to SNR improvements that enable reliable operation at data rates as high as 15 Gbit/s. These results are based on simulation and not on actual measurements or experiments. © 2015 Elsevier B.V.


Alaki S.M.,King Abdulaziz University
Oral health & preventive dentistry | Year: 2013

To investigate the prevalence and severity of dental caries in children with a history of asthma in addition to their salivary characteristics, flow rate and buffering capacity, as well as the salivary level of Mutans streptococci (MS) and lactobacilli present. The study sample was composed of 30 cases and 30 controls with an age range from 5 to 13 years. The cases involved children with a past history of asthma, while the controls were medically fit children. The study was conducted from 2010 to 2011 and patients were randomly selected through the electronic filing system at King Abdul-Aziz University Hospital (R4 system), Jeddah, Saudi Arabia. Interviews and questionnaires were completed by the parents of the children involved and dental examinations were performed. Stimulated salivary samples were collected to determine the salivary flow rate, buffering capacity and salivary levels of MS and lactobacilli. No significant differences were found in the DMFT, dmft scores or community periodontal index (CPI) scores between the cases and controls. However, there was a positive correlation between DMFT and dmft scores (r = 0.83, P < 0.0001) in both the cases and controls. In asthmatic patients who took their medication 3 times a day or more, the level of MS and lactobacilli was significantly higher (P = 0.014 and P = 0.008, respectively) compared with other asthmatic patients. Patients with severe asthma had significantly lower salivary flow rate levels than other asthmatic patients (P = 0.040), while patients taking a combination therapy of anti-asthmatic drugs with corticosteroids had higher levels of lactobacilli compared with patients using other medications (P = 0.02). The frequency of taking asthma medication, the severity of asthma and the use of combination therapy can significantly alter the salivary characteristics in asthmatic children.


AlGhamdi A.S.,King Abdulaziz University
Journal of the International Academy of Periodontology | Year: 2010

Osseous grafting represents one mode of therapy to manage periodontal osseous defects. Materials for osseous grafting can be obtained from the same person (autografts), from a different person of the same species (allografts), from a different species (xenografts), or from synthetic materials (alloplasts). The two types of grafts most frequently used in periodontal therapy are autogenous grafts and allografts. Both types can be obtained either intraorally or extraorally. They may be cancellous bone, cortical bone, or combinations of these. There has been a recent increase in interest in using xenografts and alloplasts. Bone graft materials are generally evaluated based on their osteogenic, osteoinductive, or osteoconductive potential. Selection of graft material is based on operator preference, type and size of the defect, resorbability of graft material, cost and patient acceptance. In this review we discuss different types of xenografts and alloplasts, and the advantages and disadvantages of each type.


Aly E.H.,King Abdulaziz University | Ebaid A.,University of Tabuk | Rach R.,316 S. Maple St.
Computers and Mathematics with Applications | Year: 2012

A new straightforward approach for solving ordinary and partial second-order boundary value problems with Neumann boundary conditions is introduced in this research. This approach depends mainly on the Adomian decomposition method with a new definition of the differential operator and its inverse, which has been modified for Neumann boundary conditions. The effectiveness of the proposed approach is verified by several linear and nonlinear examples. © 2012 Published by Elsevier Ltd.


Schmidbaur H.,TU Munich | Schmidbaur H.,King Abdulaziz University | Raubenheimer H.G.,Stellenbosch University | Dobrzanska L.,Catholic University of Leuven
Chemical Society Reviews | Year: 2014

In the first part of this review, the characteristics of Au-H bonds in gold hydrides are reviewed including the data of recently prepared stable organometallic complexes with gold(i) and gold(iii) centers. In the second part, the reports are summarized where authors have tried to provide evidence for hydrogen bonds to gold of the type Au⋯H-X. Such interactions have been proposed for gold atoms in the Au(-i), Au(0), Au(i), and Au(iii) oxidation states as hydrogen bonding acceptors and H-X units with X = O, N, C as donors, based on both experimental and quantum chemistry studies. To complement these findings, the literature was screened for examples with similar molecular geometries, for which such bonding has not yet been considered. In the discussion of the results, the recently issued IUPAC definitions of hydrogen bonding and the currently accepted description of agostic interactions have been used as guidelines to rank the Au⋯H-X interactions in this broad range of weak chemical bonding. From the available data it appears that all the intra- and intermolecular Au⋯H-X contacts are associated with very low binding energies and non-specific directionality. To date, the energetics have not been estimated, because there are no thermochemical and very limited IR/Raman and temperature-dependent NMR data that can be used as reliable references. Where conspicuous structural or spectroscopic effects have been observed, explanations other than hydrogen bonding Au⋯H-X can also be advanced in most cases. Although numerous examples of short Au⋯H-X contacts exist in the literature, it seems, at this stage, that these probably make only very minor contributions to the energy of a given system and have only a marginal influence on molecular conformations which so far have most often attracted researchers to this topic. Further, more dedicated investigations will be necessary before well founded conclusions can be drawn. © 2014 The Royal Society of Chemistry.


Bajwa R.S.,H+ Technology | Yaldram K.,H+ Technology | Rafique S.,King Abdulaziz University
Scientometrics | Year: 2013

In this study we present an analysis of the research trends in Pakistan in the field of nanoscience and nanotechnology. Starting with just seven publications in the year 2000, this number has steadily increased to 542 for the year 2011. Among the top 15 institutions with publications in nanotechnology 13 are universities and only two are R&D organizations. Almost 35 % of the research publications are in the field of material sciences followed by chemistry and physics in that order. The growth in the publications for period 2000-2011 is studied through relative growth rate and doubling time. The authorship pattern is measured by different collaboration parameters, like collaborative index, degree of collaboration, collaboration coefficient and modified collaboration coefficient. Finally the quality of papers is assessed by means of the h-index, g-index, hg-index and p-index. © 2012 Akadémiai Kiadó, Budapest, Hungary.


Abdalla S.,King Abdulaziz University
Progress in Biophysics and Molecular Biology | Year: 2011

Several disorder parameters, inside the DNA molecule, lead to localization of charge carriers inside potential wells in the lowest unoccupied and highest occupied molecular orbits (LUMO and HOMO) which affects drastically the electrical conduction through the molecule, and demonstrates that the band carriers play an essential role in the conduction mechanism. So, a model is presented to shed light on the role of electrons of the LUMO in the electrical conduction through the DNA molecule. DC-, AC-conductivity and dielectric permittivity experimental data are well fitted with the presented model giving evidence that the free carriers in the LUMO and HOMO are responsible to make the DNA molecule conductor, insulator or semiconductor. The obtained results show that the localized charge carriers in the DNA molecule are characterized by four different types of relaxation phenomena which are thermally activated by corresponding four activation energies at 0.56eV, 0.33eV, 0.24eV, and 0.05eV respectively. Moreover, the calculations after the model, at room temperature, show that the time of the relaxation times of the current carriers are in the order of 5×10 -2s, 1.74×10 -4s, 5×10 -7s, and 1.6×10 -10s, respectively. © 2011 Elsevier Ltd.


El Hamid Hussein R.A.,King Abdulaziz University
Journal of the Egyptian Public Health Association | Year: 2014

Background and Objectives: Breakfast skipping is prevalent among adolescents and young women, and deprives the body of important nutrients. This study was conducted to assess the correlation between breakfast eating and sociodemographic and lifestyle criteria. Participants and Methods: A cross-sectional study was carried out on a convenient sample of 400 female students selected from the female sector of King Abdulaziz University, Jeddah, Saudi Arabia. Home breakfast habit and other lifestyle characteristics were studied using a standardized questionnaire. Logistic regression was used to examine the relationship between home breakfast habit and different predictors. Results: Home breakfast skippers constituted 71.75% of the whole sample. Breakfast eaters had a significantly higher BMI compared with breakfast skippers (22.66±4.88 vs. 21.58±4.09 in home breakfast skippers; P=0.025). Irrespective of other sociodemographic and lifestyle variables, fathers' education lower than university level negatively predicted home breakfast eating [Exp B=0.40, confidence interval (CI)=0.21-0.77], and being employed positively predicted breakfast eating (Exp B=2.31, CI=1.04-5.15). Likewise, consuming less amount of junk food and fewer soft drinks (Exp B=2.57, CI=1.54-4.28, and Exp B=2.59, CI=1.39-4.81, respectively) and consuming more milk and dairy products (Exp B=1.91, CI=1.16-3.15) correlated positively with home breakfast eating. Conclusion and Recommendations: Breakfast skipping was prevalent among adolescents and young women in the studied sample. Unhealthy dietary habits, father's education lower than university level, and father being unemployed positively predicted breakfast skipping of daughters at home. This implies that breakfast eating can be encouraged by approaching parents in addition to their daughters. © 2014 Egyptian Public Health Association.


Husein D.Z.,King Abdulaziz University
Desalination and Water Treatment | Year: 2013

In this study, the removal of mercury ions by Egyptian mandarin peel was investigated in aqueous solution. Three absorbents were derived from Egyptian mandarin peel, the first adsorbent was the raw peel (MP), the second one was pretreated mandarin peel with NaOH (MNa), and the third one was carbonized mandarin peel (MC). The extent of adsorption was studied as a function of pH, adsorbent dose, temperature, and contact time. Adsorption isotherms were modeled with Langnuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms. The data fitted well with the Langmuir isotherm and the maximum monolayer adsorption capacities were found to be 19.01, 23.26, and 34.84 mg/g for MP, MNa, and MC, respectively. The kinetic data were analyzed using psudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The results indicated that Egyptian mandarin peel could be utilized as a low-cost adsorbent for mercury removal. © 2013 © 2013 Balaban Desalination Publications.


Musumeci G.,University of Catania | Szychlinska M.A.,University of Catania | Mobasheri A.,University of Surrey | Mobasheri A.,University of Nottingham | Mobasheri A.,King Abdulaziz University
Histology and Histopathology | Year: 2015

Aging is a natural process by which every single living organism approaches its twilight of existence in a natural way. However, aging is also linked to the pathogenesis of a number of complex diseases. This is the case for osteoarthritis (OA), where age is considered to be a major risk factor of this important and increasingly common joint disorder. Half of the world's population, aged 65 and older, suffers from OA. Although the relationship between the development of OA and aging has not yet been completely understood, it is thought that age-related changes correlate with other risk factors. The most prominent hypothesis linking aging and OA is that chondrocytes undergo premature aging due to several factors, such as excessive mechanical load or oxidative stress, which induce the so called “stress-induced senescent state”, which is ultimately responsible for the onset of OA. This review focuses on molecular markers and mechanisms implicated in chondrocyte aging and the pathogenesis of OA. We discuss the most important age-related morphological and biological changes that affect articular cartilage and chondrocytes. We also identify the main senescence markers that may be used to recognize molecular alterations in the extracellular matrix of cartilage as related to senescence. Since the aging process is strongly associated with the onset of preventing chondrocyte senescence, as well as the identification of new increasingly sensitive senescent markers, could have a positive impact on the development of new therapies for this severe disease. © 2015, Histology and Histopathology. All rights reserved.


Sakr S.,University of New South Wales | Liu A.,University of New South Wales | Fayoumi A.G.,King Abdulaziz University
ACM Computing Surveys | Year: 2013

In the last two decades, the continuous increase of computational power has produced an overwhelming flow of data which has called for a paradigm shift in the computing architecture and large-scale data processing mechanisms. MapReduce is a simple and powerful programming model that enables easy development of scalable parallel applications to process vast amounts of data on large clusters of commodity machines. It isolates the application from the details of running a distributed program such as issues on data distribution, scheduling, and fault tolerance. However, the original implementation of the MapReduce framework had some limitations that have been tackled by many research efforts in several followup works after its introduction. This article provides a comprehensive survey for a family of approaches and mechanisms of large-scale data processing mechanisms that have been implemented based on the original idea of the MapReduce framework and are currently gaining a lot of momentum in both research and industrial communities. We also cover a set of introduced systems that have been implemented to provide declarative programming interfaces on top of the MapReduce framework. In addition, we review several large-scale data processing systems that resemble some of the ideas of the MapReduce framework for different purposes and application scenarios. Finally, we discuss some of the future research directions for implementing the next generation of MapReduce-like solutions. © 2013 ACM.


Aly H.A.A.,King Abdulaziz University | Aly H.A.A.,Al - Azhar University of Egypt
Environmental Toxicology and Pharmacology | Year: 2013

Aroclor 1254, a commercial mixture of highly toxic environmental pollutant, is known to cause testicular toxicity. The present study was undertaken to delineate and elucidate the nature and the mechanism of action of Aroclor 1254 on rat sperm in vitro. Sperm of adult rat were incubated with 10-9M, 10-8M or 10-7M of Aroclor 1254 for 3h. Sperm motility was significantly decreased. Moreover, sperm viability, acrosome reaction and mitochondrial membrane potential (δψm) were significantly decreased in a dose-related pattern. DNA integrity was significantly decreased at 10-8M and 10-7M of Aroclor 1254, while it did not show any significant change at 10-9M. Aroclor 1254 induced downstream events included cytochrome c release and caspase-3 activation, in a dose-related manner. ATP content was decreased while protein carbonyl content was significantly increased in a dose-related manner. The oxidative stress status was also assessed. Hydrogen peroxide (H2O2) production and lipid peroxidation (LPO) were significantly increased in a dose-related pattern. The antioxidant enzymes SOD, CAT and GPx were significantly decreased, while at a concentration of 10-9M of Aroclor 1254, GR activity did not show any significant change. The non-enzymatic antioxidant (GSH) was significantly decreased in a dose-dependent manner. In conclusion; our data clearly show that Aroclor 1254 induces toxicity, oxidative stress and culminating in mitochondria mediated apoptosis in rat sperm. © 2013.


Kada B.,King Abdulaziz University
Journal of Guidance, Control, and Dynamics | Year: 2014

This paper investigates the development and implementation of a new homing-missile guidance system for intercepting highly maneuverable targets using arbitrary features of the homogeneous high-order sliding-mode controllers and observers. The concept of this guidance system involves artificially increasing the orders of controllers and observers to enhance accuracy and robustness of future interceptors. Two advanced guidance laws, that is, augmented proportional navigation law and direct collision or hit-to-kill law, are considered to construct acceleration-based and velocity-based attractive sliding manifolds, respectively; and high-order robust exact differentiators are used to compute high-order time derivatives of these manifolds. Real-time estimation of target maneuver from measurements using these differentiators is also considered. The resulting guidance laws are implemented in computer simulation using nonlinear interceptor dynamics and engagement kinematics. The results prove that the guidance system achieves high-level performance and successfully meets direct collision guidance requirements. In addition, this system shows good adaptability and strong robustness to target evasive maneuvers, parameter uncertainties, and measurement noises. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Taylan O.,King Abdulaziz University
Applied Soft Computing Journal | Year: 2013

The main idea behind this study is to introduce a fuzzy grey relational methodology (FGRM) to determine the importance of customer attributes' (CAs) for edible oil, particularly for defining the opportunity of competitiveness which has recently become one of an important concern of manufacturing companies. It was also aimed to seek high quality level of product and process characteristics for meeting the desirability of attributes and for health care. A fuzzy grey inference system was employed with the support of fuzzy quality function (QFD) deployment to interpret the qualitative and imprecise customer attributes. Fuzzy QFD is relatively a recent methodology offering a more in-depth analysis and investigation into the handling of customer requirements and engineering characteristics. The attributes then were defuzzified into quantitative values by amalgamating the knowledge of the customers and the product designers. Customer needs (CNs) are the voice of customers and tend to be linguistic naturally. In this study, fuzzy inference system (FIS) along with fuzzy QFD was employed to determine the desirability of edible oil by consumers. Fuzzy QFD is a powerful tool for improving product design and quality, and procuring a customer-driven quality system. The integrated framework based on FIS, fuzzy QFD and FGRM determined the CAs relations, and desirability level of edible oil by consumers. The findings are not only meaningful for customers, but also important for market position of product. The methodology significantly reduces the complexity of decision making and increase the production efficiency and overall competitiveness. © 2012 Elsevier B.V. All rights reserved.


Kuhnis J.,University of Zurich | Elmer S.,University of Zurich | Jancke L.,University of Zurich | Jancke L.,King Abdulaziz University
Journal of Cognitive Neuroscience | Year: 2014

Currently, there is striking evidence showing that professional musical training can substantially alter the response properties of auditory-related cortical fields. Such plastic changes have previously been shown not only to abet the processing of musical sounds, but likewise spectral and temporal aspects of speech. Therefore, here we used the EEG technique and measured a sample of musicians and nonmusicians while the participants were passively exposed to artificial vowels in the context of an oddball paradigm. Thereby, we evaluated whether increased intracerebral functional connectivity between bilateral auditory related brain regions may promote sensory specialization in musicians, as reflected by altered cortical N1 and P2 responses. This assumption builds on the reasoning that sensory specialization is dependent, at least in part, on the amount of synchronization between the two auditory-related cortices. Results clearly revealed that auditory-evoked N1 responses were shaped by musical expertise. In addition, in line with our reasoning musicians showed an overall increased intracerebral functional connectivity (as indexed by lagged phase synchronization) in theta, alpha, and beta bands. Finally, within-group correlative analyses indicated a relationship between intracerebral beta band connectivity and cortical N1 responses, however only within the musiciansʼ group. Taken together, we provide first electrophysiological evidence for a relationship between musical expertise, auditory-evoked brain responses, and intracerebral functional connectivity among auditory-related brain regions. © 2014, Massachusetts Institute of Technology.


El-Zahrani H.A.,King Abdulaziz University
Journal of the Egyptian Society of Parasitology | Year: 2011

The presence of heavy metals in aquatic environments is known to cause severe damage to aquatic life, beside the fact that these metals kill microorganisms during biological treatment of wastewater with a consequent delay of the process of water purification. Most of the heavy metal salts are soluble in water and form aqueous solutions and consequently cannot be separated by ordinary physical means of separation. Five bacterial strains were used in this study. Bacterial strains were marking using 10 antibiotics and 7 heavy metals to be use as a selectable markes in conjugation process. Mating were performed using five bacterial strains. These strains were genetically marking in relation to their tolerance to the different antibiotics and heavy metals. All matings between bacterial strains were successes. The biosorption capacities for all heavy metals determined were higher for some metals than others. The transconjugants strain Tr5 resulted from mating between the parental bacterial strains (B-6bs X B-21) was more efficient in molybdenum uptake than all bacterial strains when supplementednutrient media wi th wastewater. Bacterial strains (B-21) appeared a good uptake of heavy metal ions (copper, cadmium, iron, cadmium and Lead) than other bacterial strains. This work highlights the potential of bacterial strains B-21 in uptake of heavy metals. The transconjugant strain Tr3 resulted from mating between parental bacterial strains (B-1584 X B-287) was more efficient in chromium uptake than all bacterial strains.


Andanson J.-M.,ETH Zurich | Baiker A.,ETH Zurich | Baiker A.,King Abdulaziz University
Journal of Physical Chemistry C | Year: 2013

The interface between 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EmIm][OTf]) ionic liquid (IL) supported on alumina nanoparticles and organic solvents (ethanol, tetrahydrofuran and acetonitrile) has been investigated using infrared (IR) spectroscopy. The investigations of these liquid-solid interfaces were preceded by separate studies of the IL in the different solvents and the IL supported on the alumina nanoparticles. IR analyses of the solvent-[EmIm][OTf] mixtures indicated that the triflate anion interacts differently with the three solvents. Comparison of the spectra of the IL supported on alumina with those measured for the corresponding solvent-IL mixtures indicates an interaction between the SO3 group of the anion and the alumina surface. In the organic solvent-IL-alumina systems, similar interactions between the IL and the oxide surface occur. The behavior of the IL/alumina interfaces was found to be consistent with a model where the ionic liquid structure is perturbed due to charge neutralization in a thin layer at the interface. Qualitative studies of the kinetics of adsorption and desorption of the IL in the organic liquid phases indicated that the choice of the organic solvent has a significant influence on these processes. Comparative studies with a commercial Pt on alumina catalyst possessing similar surface area showed that the IL uptake strongly increases in the presence of Pt on the alumina surface. Comparison of adsorption-desorption cycles of the IL measured for the alumina support and Pt on alumina revealed a much stronger interaction of the IL with the Pt surface than with the alumina. © 2013 American Chemical Society.


Rahman M.M.,King Abdulaziz University
Current Proteomics | Year: 2012

Acetylcholine (ACh) biosensor is developed based on mediator-free acetylcholine oxidase (AChOx) by self-assembled monolayer (SAM) onto lab-made micro-chip. The simple cyclic voltammetry (CV) method is utilized in mediator-free system in phosphate buffer solution (PBS, 0.1M) at room conditions. The analytical parameters of AChOx fabricated electrode employed a lower detection limit (DL, 0.136 nM), a wide linear dynamic range (LDR, 1.0 nM to 1.0 mM), good linearity (R= 0.9991), and higher sensitivity (2.7329 μAmM-1cm-2) where a tiny sample volume (70.0 μL) is required. The micro-chip system executes a simple and efficient approach to immobilize the enzymes onto SAM modified surface, which can improve the biosensor performances for a large group of biomolecules in broad scale of biomedical applications in health-care fields. © 2012 Bentham Science Publishers.


Harris I.,University of East Anglia | Jones P.D.,University of East Anglia | Jones P.D.,King Abdulaziz University | Osborn T.J.,University of East Anglia | Lister D.H.,University of East Anglia
International Journal of Climatology | Year: 2014

This paper describes the construction of an updated gridded climate dataset (referred to as CRU TS3.10) from monthly observations at meteorological stations across the world's land areas. Station anomalies (from 1961 to 1990 means) were interpolated into 0.5° latitude/longitude grid cells covering the global land surface (excluding Antarctica), and combined with an existing climatology to obtain absolute monthly values. The dataset includes six mostly independent climate variables (mean temperature, diurnal temperature range, precipitation, wet-day frequency, vapour pressure and cloud cover). Maximum and minimum temperatures have been arithmetically derived from these. Secondary variables (frost day frequency and potential evapotranspiration) have been estimated from the six primary variables using well-known formulae. Time series for hemispheric averages and 20 large sub-continental scale regions were calculated (for mean, maximum and minimum temperature and precipitation totals) and compared to a number of similar gridded products. The new dataset compares very favourably, with the major deviations mostly in regions and/or time periods with sparser observational data. CRU TS3.10 includes diagnostics associated with each interpolated value that indicates the number of stations used in the interpolation, allowing determination of the reliability of values in an objective way. This gridded product will be publicly available, including the input station series (http://www.cru.uea.ac.uk/ and http://badc.nerc.ac.uk/data/cru/). © 2013 Royal Meteorological Society.


Rouzi A.A.,King Abdulaziz University
Clinical and Experimental Obstetrics and Gynecology | Year: 2013

Purpose: To report a case of urethral sex in a woman with previously undiagnosed Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome. Materials and Methods: A 32-year-old woman presented with severe pain, dysuria, and mild hematuria after each intercourse. Secondary sexual characteristics were normal. Vaginal and rectal examinations revealed an absent vagina and uterus. Further investigations showed a normal hormonal profile, a 46 XX karyotype, and a normal intravenous pyelography. Pelvic ultrasonography and magnetic resonance imaging (MRI) confirmed the absence of a uterus and the presence of bilateral ovaries. Results: A diagnosis of MRKH syndrome was made and the patient underwent a modified Vecchietti operation for the creation of a new vagina. The urethral meatus was noticeably dilated. Postoperatively, the vaginal length was six to seven cm. Long-term follow-up revealed that she was able to have normal and satisfactory vaginal intercourse without any problems. Conclusion: Urethral intercourse is documented here for the first time in a case of misdiagnosed MRKH syndrome.


Purpose: Knowledge is a main resource of any organization. Knowledge management (KM) is identified by four processes: creating, capturing, distributing and sharing of knowledge. Technology can enable successful KM. The purpose of this paper is to propose a technology knowledge management (TKM) taxonomy, which lists popular electronic tools that can enhance KM processes and shows which tool can contribute to which processes. Design/methodology/approach: The taxonomy was developed by an extensive literature review of electronic KM tools and a three-year extensive analysis of different knowledge sources at the Jeddah Municipality (JM) in Saudi Arabia. Findings: The taxonomy can be used by practitioners developing an organizational KM system to guide them to choose a sufficient subset of tools that covers all four processes in order to ensure that no process is overlooked. Research limitations/implications: The result of using the TKM taxonomy and its effect on KM success is an interesting area for further research. However, the current value underlies in it offering practitioners a rough roadmap to an electronic KM system and aids in giving at least a starting point. Practical implications: The TKM taxonomy can be used by large scale organizations to guide in developing a KM system effectively and more efficiently. Furthermore, the JM KC is a good model for similar organizations to use, with all the tools explained in the paper. Social implications: The paper addresses some of the social elements related to successful KM in organizations. However, it is more technically targeted. Originality/value: Researchers have investigated either the holistic effect of IT on KM or described certain tools. The types of IT tools and their effect on KM have not been investigated. Furthermore, limited research addresses the design of effective KM systems and no tools exist to guide designers. The TKM taxonomy is a tool that can help KM practitioners and strategists to design effective KM systems efficiently, by guiding them in choosing tools that are suitable for certain KM processes. The paper also describes the JM Knowledge Center as a KMS model for organizations which addresses all four KM processes. © Emerald Group Publishing Limited.


Habib H.S.,King Abdulaziz University
Pakistan Journal of Medical Sciences | Year: 2013

Background: Transition from a parallel circulation in utero to an in-series circulation immediately after birth is partly an oxygen-dependent process. Relative hypoxemia with increasing altitude above sea level exerts a certain degree of stress on oxygen-dependent metabolic processes throughout the body. Objective: The present study aimed to determine the reference values for oxygen saturation and the pre-ductal and post-ductal oxygen saturation trends during the first 60 min of life in healthy full-term neonates born at moderate altitude (1500-2500 m) using pulse oximetry. Methods: This descriptive study was carried out over a period of three months started from July 2011 in the Neonatology Department of King Abdulaziz Specialist Hospital, Taif, Saudi Arabia. In this observational study, arterial oxygen saturation in the right hand and right foot of each infant was recorded by pulse oximetry immediately after birth and continuously within the first 60 min of life. The respiratory rate, heart rate, and blood pressure were measured at birth and at 1 h after birth. Cord blood gas and haemoglobin levels were also measured. Results: The study was conducted in a hospital situated at an altitude of 1640 m above sea level. Immediately after birth, the mean pre-ductal SpO2 in the right hand was 68% (51-80%); in the right foot, the mean post-ductal SpO2 was 60% (40-77%). This difference was statistically significant (p < 0.01); however, it became statistically insignificant at 20 min (4-45 min) and disappeared at 25 min, when the SpO2 in both limbs equalised at 88% (83-96%). SpO2 levels > 94% were reached after 13 min (4-35) min pre-ductally and after 22 min (10-45 min) post-ductally. The mean respiratory rate, heart rate, and mean blood pressure at birth were 56/min, 140/min, and 34 mmHg, respectively; at 60 min, they were 40/min, 123/min, and 47 mmHg, respectively. Conclusion: This study defined normal range of SpO2 values in healthy full-term neonates born at moderate altitude in the first 60 minutes of life. These are expected to serve as base line data for normal neonates born at similar altitudes. With regard to pre-ductal and post-ductal oxygen saturation levels, cut-off values lower than those used at sea level should be adopted for neonates born at moderate altitudes.


Chou K.-C.,Gordon Life Science Institute | Chou K.-C.,King Abdulaziz University
Molecular BioSystems | Year: 2013

Many molecular biosystems and biomedical systems belong to the multi-label systems in which each of their constituent molecules possesses one or more than one function or feature, and hence needs one or more than one label to indicate its attribute(s). With the avalanche of biological sequences generated in the post genomic age, it is highly desirable to develop computational methods to timely and reliably identify their various kinds of attributes. Compared with the single-label systems, the multi-label systems are much more complicated and difficult to deal with. The current mini review focuses on the recent progresses in this area from both conceptual aspects and detailed mathematical formulations. © 2013 The Royal Society of Chemistry.


Shanmugam A.,University of Melbourne | Ashokkumar M.,University of Melbourne | Ashokkumar M.,King Abdulaziz University
Food Hydrocolloids | Year: 2014

This study reports the incorporation of 7-21% of flax seed oil in pasteurized homogenized skim milk (PHSM) using high intensity ultrasound (US) at 20kHz between 1 and 8min and at varying power levels. A minimum process time of 3min at an applied acoustic power of 176W was sufficient to produce emulsion droplets (7% oil) with an average mean volume diameter of 0.64μm and they were stable at least 9 days at 4±2°C. The mechanical, cavitational and cavitation-after-effects of US are responsible for the production of smaller sized emulsion droplets and process-induced modifications of milk proteins. A very small proportion (less than 20%) of partially denatured whey proteins provided stability to the emulsion droplets. The emulsion droplets also showed a surface potential of about-30mV due to the adsorbed proteins, which provided further stability to the emulsion droplets due to electrostatic repulsion. In order to see if other high shear techniques can generate stable emulsions, experiments were carried out using Ultraturrax (UT) at similar energy densities to that of US. UT did not produce stable emulsions until 20min of processing suggesting the superiority of US emulsification process. © 2014 Elsevier Ltd.


Kishta W.,King Abdulaziz University
Journal of Pediatric Orthopaedics | Year: 2015

BACKGROUND:: Osteogenesis imperfecta (OI) is a heritable skeletal disorder characterized by bone fragility and short stature that is usually due to mutations in 1 of the 2 genes that code for collagen type I α-chains. The association between hip dysplasia and OI has not been systematically investigated. In this single-center study, we retrospectively reviewed all cases of OI associated with hip dysplasia to describe clinical characteristics and the effect of therapy. METHODS:: We reviewed the charts of 687 patients with OI who were seen at the Shriners Hospital for Children in Montreal between 1999 and 2013 to identify patients with a diagnosis of hip dysplasia. Clinical characteristics and the course after therapeutic interventions were extracted from the charts. RESULTS:: Hip dysplasia was diagnosed in 8 hips of 5 patients (4 boys, 1 girl; age at diagnosis ranged between 3 wk and 27 mo old). The prevalence of hip dysplasia and OI was therefore 0.87% (per patient). In 4 of the 5 patients (80%), OI was caused by mutations affecting the C-propeptide of collagen type I, which is otherwise rare in OI. Among the 26 patients with C-propeptide mutations followed at our institution, 4 (15%) had hip dysplasia. Pavlik harness treatment was attempted in 2 patients (3 hips) but was not effective in either case and resulted in avascular necrosis of 1 hip. Femoral varus derotational shortening osteotomies using a telescopic rod were performed in all 8 hips along with a closed reduction in 4 hips and an open reduction in 4 hips. Concomitant pelvic osteotomies were performed in 2 hips (1 patient). Surgery resulted in redislocation of 1 hip; all other surgically treated hips remained reduced. CONCLUSIONS:: Clinical screening for hip dysplasia is difficult in OI owing to the bowing of the proximal femur and the risk of causing fractures. OI patients with positive C-propeptide mutation should therefore be screened for hip dysplasia by use of ultrasound. Presence of a C-propeptide mutation appears to be a risk factor for hip dysplasia (80%). It appears that Pavlik harness treatment is not useful in children with OI. The usual treatment of children with OI who pull to stand or started walking with femoral deformity is femoral osteotomy and rodding. In case of associated hip dysplasia with a dislocation, open reduction of the hip and a possible concomitant pelvic osteotomy appears to be a valid management option. LEVEL OF EVIDENCE:: Level IV. © 2015 Wolters Kluwer Health, Inc. All rights reserved.


Pedrycz W.,University of Alberta | Pedrycz W.,King Abdulaziz University | Pedrycz W.,Polish Academy of Sciences | Song M.,University of Alberta
Information Fusion | Year: 2014

To be fully utilized, linguistic information present in decision-making, has to be made operational through information granulation. This study is concerned with information granulation present in the problems of Analytic Hierarchy Process (AHP), which is available in the characterization of a pairwise assessment of alternatives studied in the decision-making problem. The granulation of entries of reciprocal matrices forming the cornerstone of the AHP is formulated as a optimization problem in which an inconsistency index is minimized by a suitable mapping of the linguistic terms on the predetermined scale. Particle Swarm Optimization is used as an optimization framework. Both individual and group decision-making models of AHP are discussed. © 2011 Elsevier B.V. All rights reserved.


Heal M.R.,University of Edinburgh | Kumar P.,University of Surrey | Harrison R.M.,University of Birmingham | Harrison R.M.,King Abdulaziz University
Chemical Society Reviews | Year: 2012

The diversity of ambient particle size and chemical composition considerably complicates pinpointing the specific causal associations between exposure to particles and adverse human health effects, the contribution of different sources to ambient particles at different locations, and the consequent formulation of policy action to most cost-effectively reduce harm caused by airborne particles. Nevertheless, the coupling of increasingly sophisticated measurements and models of particle composition and epidemiology continue to demonstrate associations between particle components and sources (and at lower concentrations) and a wide range of adverse health outcomes. This article reviews the current approaches to source apportionment of ambient particles and the latest evidence for their health effects, and describes the current metrics, policies and legislation for the protection of public health from ambient particles. A particular focus is placed on particles in the ultrafine fraction. The review concludes with an extended evaluation of emerging challenges and future requirements in methods, metrics and policy for understanding and abating adverse health outcomes from ambient particles. © The Royal Society of Chemistry 2012.


Sait H.H.,King Abdulaziz University
Energy Conversion and Management | Year: 2013

Electric energy consumption is becoming an important issue for individual as well as for governmental and private organizations. Electric companies in Saudi Arabia face hard times in meeting the increasing demand for electric power. This research investigation is trying to study the electric energy consumption for an educational building located in Rabigh city, 150 km North of Jeddah city, Saudi Arabia. Detailed auditing was done to the building including constructing materials used, energy consumption, cooling load and lighting. Temperature and relative humidity were recorded for several places inside the building. Thermal images for the interior zones were generated to provide information about the temperature distribution and give an idea about air or heat leak from or into the building. Based on the analysis of auditing exercise, some recommendations were suggested to reduce the electric energy consumptions which can reach up to 35.3%. The A/C units' efficiency can also be increased by 31%. The results will be beneficial for the educational organizations and operation and maintenance staff to manage the electric usage and reduce the electric bills. © 2012 Elsevier Ltd. All rights reserved.


Nicholls D.C.,Australian National University | Dopita M.A.,Australian National University | Dopita M.A.,King Abdulaziz University | Sutherland R.S.,Australian National University
Astrophysical Journal | Year: 2012

The measurement of electron temperatures and metallicities in H II regions and planetary nebulae (PNe) has - for several decades - presented a problem: results obtained using different techniques disagree. What is worse, they disagree consistently. There have been numerous attempts to explain these discrepancies, but none has provided a satisfactory solution to the problem. In this paper, we explore the possibility that electrons in H II regions and PNe depart from a Maxwell-Boltzmann equilibrium energy distribution. We adopt a "κ-distribution" for the electron energies. Such distributions are widely found in solar system plasmas, where they can be directly measured. This simple assumption is able to explain the temperature and metallicity discrepancies in H II regions and PNe arising from the different measurement techniques. We find that the energy distribution does not need to depart dramatically from an equilibrium distribution. From an examination of data from H II regions and PNe, it appears that κ ≳ 10 is sufficient to encompass nearly all objects. We argue that the kappa-distribution offers an important new insight into the physics of gaseous nebulae, both in the Milky Way and elsewhere, and one that promises significantly more accurate estimates of temperature and metallicity in these regions. © 2012. The American Astronomical Society. All rights reserved..


Yen C.-P.,Inter Digital Communications | Tsai Y.,Inter Digital Communications | Wang X.,Columbia University | Wang X.,King Abdulaziz University
IEEE Transactions on Signal Processing | Year: 2013

In this paper, we consider the problem of locating multiple active spectrum subbands in a wide range of frequency bands. A major challenge associated with such wideband spectrum sensing is that it is either infeasible or too expensive to perform Nyquist sampling on the wideband signal. In this paper, we propose a sensing scheme based on a sub-Nyquist sampling method called multicoset sampling, which is similar to the polyphase implementation of the Nyquist sampling, but requires less A/D converters. In contrast to the traditional sub-Nquist approaches where the wideband signal is first reconstructed from the sub-Nyquist samples, we develop a method that directly estimates the power spectrum of the wideband signal of interest using the sub-Nyquist samples, by exploiting its statistical properties. We also characterize the statistical distribution of the proposed power spectrum estimator, based on which we obtain a constant-false-alarm energy detector for the frequency bins. Simulation results are provided to demonstrate the effectiveness of the proposed multiband spectrum sensing method based on sub-Nyquist sampling. © 1991-2012 IEEE.


Dalir H.,Tokyo Institute of Technology | Koyama F.,Tokyo Institute of Technology | Koyama F.,King Abdulaziz University
Applied Physics Letters | Year: 2013

A concept for the bandwidth enhancement of directly modulated vertical-cavity surface emitting lasers (VCSELs) using a transverse-coupled- cavity (TCC) scheme is proposed, which enables us to tailor the modulation-transfer function. A bow-tie shaped oxide aperture forms the transverse-coupled cavity resulting in optical feedback to boost the modulation speed. While the bandwidth of conventional VCSELs is 9-10 GHz, the 3 dB-bandwidth of the TCC VCSEL is increased by a factor of 3 far beyond the relaxation-oscillation frequency. The maximum bandwidth is currently limited by the photo-detector used in the experiment. Clear 36 Gbps eye opening was attained with an extinction ratio of 4 dB. © 2013 AIP Publishing LLC.


Khaled A.-R.A.,King Abdulaziz University | Vafai K.,University of California at Riverside
International Journal of Heat and Mass Transfer | Year: 2014

Enhancement of heat transfer in minichannels due to co-flowing of two immiscible fluids in a direct contact is investigated in this work. Different fluid combinations are analyzed. The momentum and energy equations for both flows are solved analytically and numerically. The numerical and analytical solutions are found to be in good agreement. A parametric study including the influence of fluids relative viscosity, thermal conductivity, thermal capacity and height ratios is conducted for various Peclet numbers. Different ranges of the parameters that augment the heat transfer are obtained, and different physical aspects of the problem are discussed. For practical fluid combinations with small Peclet numbers, the enhancement factor can increase up to 2.6 folds. However, that increase is about 1.2 folds when the Peclet number is increased by two orders of magnitude. This work establishes the mechanisms for heat transfer enhancement utilizing two immiscible co-flows. © 2013 Elsevier Ltd. All rights reserved.


Belsky J.,University of California at Davis | Belsky J.,King Abdulaziz University | Belsky J.,Birkbeck, University of London | Pluess M.,Queen Mary, University of London
Development and Psychopathology | Year: 2013

We provide a theoretical and empirical basis for the claim that individual differences exist in developmental plasticity and that phenotypic plasticity should be a subject of study in its own right. To advance this argument, we begin by highlighting challenges that evolutionary thinking poses for a science of development and psychopathology, including for the diathesis-stress framework that has (fruitfully) guided so much empirical inquiry on developmental risk, resilience, and dysregulation. With this foundation laid, we raise a series of issues that the differential-susceptibility hypothesis calls attention to, while highlighting findings that have emerged over just the past several years and are pertinent to some of the questions posed. Even though it is clear that this new perspective on Person × Environment interaction is stimulating research and influencing how hypotheses are framed and data interpreted, a great many topics remain that need empirical attention. Our intention is to encourage students of development and psychopathology to treat phenotypic plasticity as an individual-difference construct while exploring unknowns in the differential-susceptibility equation. © 2013 Cambridge University Press.


Mokhtar G.A.,King Abdulaziz University
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation, Saudi Arabia | Year: 2011

Immunoglobulin M nephropathy (IgMN) is an idiopathic glomerulonephritis characterized by a variable degree of mesangial hyper- cellularity and diffuse IgM deposits. This study describes the clinical presentation and the morphological findings in 36 patients, five adults and 31 children, with IgMN. The initial manifestations of the disease were the nephrotic syndrome in 32 patients, proteinuria in two, hematuria associated with proteinuria in 16 and isolated recurrent gross hematuria in two patients. The nephrotic syndrome was steroid responsive in 9% of the cases, steroid dependent in 25% and steroid resistant in 66%. Five patients were hypertensive at the onset of the disease. The mean follow- up period was 3.4 years (range, 1-7 years). One patient developed end- stage kidney disease five years after the diagnosis. On light microscopy, 24 specimens showed mild focal and segmental mesangial hyper- cellularity, 10 cases were normal in cellularity and two cases showed diffuse global mesangial hyper- cellularity. Four cases showed focal and segmental glomerulosclerosis. Mild interstitial inflammation and fibrosis were observed in 11 cases and focal tubular atrophy and hypertensive hyaline arteriosclerosis were noted in three cases. In addition to IgM, the immunofluorescence study showed C3 deposits in 12 cases, IgG in nine cases and IgA in one case. Electron dense- deposits in the mesangium and para- mesangial areas were demonstrated on electron microscopy in 22 cases. In view of its different clinical presentations and the constant findings of diffuse mesangial IgM deposition in all the cases, it is concluded that this form of nephropathy constitutes a distinct entity separate from minimal change disease or focal and segmental glomerulosclerosis. Patients with IgMN had a higher prevalence of steroid resistance and dependence in the proteinuric group.


Abu-Hamdeh N.H.,King Abdulaziz University
Journal of Materials Processing Technology | Year: 2014

A cantilever type rotating bending testing machine was used to test several welded specimens, these consisted of welding of steel ST60 to stainless steel SS304, and welding of steel ST60 to stainless steel SS316, using different filler types of stainless steel SS308, SS309 and SS310. The effect on the heat affected zone (HAZ) was investigated. Fracture surface examinations were also carried out. The numerical analysis adopted the finite element package ABAQUS® to model the welded specimens. Elasto-plastic non-linear analysis was conducted for stress distribution contours. von Mises stresses were obtained as well as crack initiation fatigue life. Both numerical and experimental studies were carried out at four different levels of applied stress from 0.6Sy to 1.2Sy at steps of 0.2Sy. The developed maximum stresses exhibited linear behavior followed by non-linear behavior with further increase of applied stress. The filler type had a pronounced effect on the developed stress such that higher stresses were obtained for filler SS308 and lower stresses for SS309 and for SS310, respectively. The crack initiation fatigue life decreased non-linearly with increasing the applied stress and it was greatly affected by the type of filler material; filler SS310 had higher fatigue life cycles than SS309 while SS308 had the lowest fatigue life cycles. The crack initiation fatigue life (N i) and failure life (Nf) exponentially decreased with the increase in the applied stress. The experimental and numerical results were in good agreement. The SS310 filler, which has the highest Cr%, Mn% and Ni% is the best filler for welding ST60 to SS304 and also for welding ST60 to SS304, and it is recommended for such welding applications. © 2014 Elsevier B.V.


Singh A.K.,Brigham and Womens Hospital | Singh A.K.,Harvard University | Kari J.A.,King Abdulaziz University
Current Opinion in Nephrology and Hypertension | Year: 2013