Alqhtani N.R.,University College London |
Alqhtani N.R.,Sattam bin Abdulaziz University |
Logan N.J.,University College London |
Meghji S.,University College London |
And 2 more authors.
Bone Reports | Year: 2017
Since the 1980s, titanium (Ti) implants have been routinely used to replace missing teeth. This success is mainly due to the good biocompatibility of Ti and the phenomenon of osseointegration, with very early events at implant placement being important in determining good osseointegration. However, enhancing implant performance with coatings such as hydroxyapatite (HA) and calcium phosphate has proved largely unsuccessful. Human mesenchymal stem cells (hMSCs) are the first osteogenic cells to colonise implant surfaces and offer a target for enhancing osseointegration. We previously reported that small doses of bisphosphonate (BP) may play an integral role in enhancing hMSC proliferation and osteogenic differentiation. The aim of this study is to investigate whether small doses of bisphosphonates enhance proliferation and osteogenic differentiation of hMSCs on Ti surfaces, to enhance bone osseointegration and to accelerate wound healing around the implant surface. Our data suggests that treating cells with small doses of BP (100 nM & 10 nM) induces significant hMSC stimulation of osteogenic markers including calcium, collagen type I and ALP compared to control group on titanium surfaces (P < 0.05). In addition, cell proliferation and migration were significantly enhanced on titanium surfaces (P < 0.05). © 2017 The Authors
Ibrahim A.,Sattam Bin AbdulAziz University |
Ibrahim A.,Electronics Research Institute of Egypt |
Gebali F.,University of Victoria
Journal of Signal Processing Systems | Year: 2016
We present low area and low power semi-systolic array architectures for polynomial basis multiplication over GF(2m) using Progressive Multiplier Reduction Technique (PMR). These architectures are explored using linear and nonlinear techniques applied to the polynomial multiplication algorithm. The nonlinear techniques allow the designer, to control the processor workload and reduce the inter-processor communications. The semi-systolic architectures obtained have simple structure with local communication. ASIC implementations of our designs and comparable published designs show that the proposed scalable semi-systolic structures have less area complexity (56.8–94.6 %) and power consumption (55.2–84.2 %) except for a scalable design published by the same authors. However, one of the proposed scalable designs outperforms this design in terms of throughput by 73.8 %. This makes the proposed designs suited to embedded applications that require low power consumption and moderate speed. © 2015, Springer Science+Business Media New York.
Aldhaifallah M.,Prince Sattam bin Abdulaziz University Prince |
Nisar K.S.,Sattam bin Abdulaziz University
13th International Multi-Conference on Systems, Signals and Devices, SSD 2016 | Year: 2016
In this paper we develop a new algorithm to identify Auto-Regressive Exogenous (ARX) input Hammerstein Models based on Twin Support Vector Machine Regression (TSVR). The model is determined by minimizing two ϵ-insensitive loss functions. One of them determines the ϵ1-insensitive down bound regressor while the other determines the ϵ1-insensitive up bound regressor. The algorithm is compared to Support Vector Machine (SVM) and Least Square Support Vector Machine (LSSVM) based algorithms using simulation. © 2016 IEEE.
Ibrahim M.F.,University of Quebec at Chicoutimi |
Alkahtani S.A.,Sattam bin Abdulaziz University |
Abuhasel K.,Sattam bin Abdulaziz University |
Samuel F.H.,University of Quebec at Chicoutimi
Materials and Design | Year: 2015
The present work was performed on B357 alloy containing Mg, Fe, Be and Sr. The molten metal was cast in a metallic mold (ASTM B-108). The Mg level of the alloy was increased by adding pure Mg to the alloy melts to obtain Mg levels of 0.4wt.%, 0.6wt.% and 0.8wt.%. Iron and Be were added in the form of Al-25%Fe and Al-5%Be master alloys, respectively, to obtain Fe levels of 0.09wt.%, 0.2wt.% and 0.6wt.% and a Be level of 0.05wt.%. The beryllium-iron phase is observed to occur in script-like form inside primary α-Al dendrites and close to Fe phases. Increasing both Mg and Fe levels in the alloy increases the amount of the π-Al8FeMg3Si6 phase formed. In solution heat-treated alloys, the β-phase platelets are observed to undergo changes in their morphology due to the dissolution, thinning, necking, and fragmentation of these platelets with an increase in solutionizing time. The π-phase is observed to dissolve and/or transform into a cluster of very fine β-Al5FeSi phase platelets. Beryllium addition results in a nodular form of the β-phase which decreases the harmful effects of these particles on the mechanical properties. Quality index values increase with an increase in solution heat treatment time, from 5 to 12h. Raising the Mg content leads to an increase in tensile parameters. Raising the Fe levels, however, leads to a drastic decrease in properties. For the same levels of Fe and/or Mg, Be and Sr help to improve the alloy mechanical properties. This is more prominent in alloys containing low levels of Fe with high levels of Mg. © 2015 Elsevier Ltd.
Chaieb M.,Sattam bin Abdulaziz University |
Chaieb M.,University of Tunis |
Jemai J.,University of Bahrain |
Mellouli K.,University of Tunis
Procedia Computer Science | Year: 2015
Complex Optimization Problems has existed in many fields of science, including economics, healthcare, logistics and finance where a complex problem has to be solved. Thus, modeling a complex problem is a fundamental step to relax its complexity and achieve to a final solution of the master problem. Hierarchical optimization is a main step in optimization problems handling process. It consists of decomposing an optimization problem into two or more sub-problems; each sub-problem has its own objectives and constraints. It will help to prove the correct understanding and represent the problem in a different form that facilitates its solving. In this work, we stipulate that a hierarchical decomposition of complex problems can yield to more effective solutions. The proposed framework will contain four possible strategies which will be detailed through this paper; objective based decomposition; constraints based decomposition, semantic decomposition and data partitioning strategy. Each strategy will be argued by a set of examples from the literature to validate our framework. However, some conditions shall be verified to model the problem using such conditions are problems' characteristics that will help to identify if a combinatorial optimization problem can be modeled within the proposed framework and they are detailed in the following subsections. © 2015 The Authors. Published by Elsevier B.V.
PubMed | Sattam bin Abdulaziz University, Taibah University and King Saud University
Type: Comparative Study | Journal: International orthodontics | Year: 2015
To compare the percentage force decay of clear and semi-clear elastomeric chain products from eight different manufacturers and to evaluate the amount of discoloration after immersion in colored dietary media of the same elastomeric chain products.An in vitro study was designed using an electronic force gauge to measure six samples from each of 19 types of elastomeric chains stretched for a period of four weeks. A spectrophotometer was used to measure the color of each specimen (10 of each type) at baseline and after being soaked in a dietary medium (coffee, tea, cola, and wine in 250 ml amounts) for 72 h.There was a significant difference in the percentage of the lost initial force between all the tested E-chains (P<0.001). ANOVA shows a significant difference in the amount of discoloration between the E-chain types (P<0.001). Semi-clear (tooth-color/pearl/obscure) E-chain types (TP-ToothC, OrthO-Pearl, GAC-SiliPearl, 3M-Obscure) present significantly less change in color than clear E-chains of the same brand (TP-Clear, OrthoO-Clear, GAC-SiliClear, 3M-Clear).Significant differences in the mean percentage force decay between the 19 studied clear elastomeric chain types were present. AO-Memory and Ormco maintained most of their original force at the end of the four-week interval. Significant differences in discoloration also exist between the various types of E-chains. TP Orthodontics (Tooth-Colored, SuperSlick, Clear) and Ortho Organizers (Pearl) showed the least discoloration.
PubMed | Sattam bin Abdulaziz University, King Saud University, Salman bin Abdulaziz University and University of Bradford
Type: Journal Article | Journal: Molecules (Basel, Switzerland) | Year: 2015
A library of 53 benzimidazole derivatives, with substituents at positions 1, 2 and 5, were synthesized and screened against a series of reference strains of bacteria and fungi of medical relevance. The SAR analyses of the most promising results showed that the antimicrobial activity of the compounds depended on the substituents attached to the bicyclic heterocycle. In particular, some compounds displayed antibacterial activity against two methicillin-resistant Staphylococcus aureus (MRSA) strains with minimum inhibitory concentrations (MICs) comparable to the widely-used drug ciprofloxacin. The compounds have some common features; three possess 5-halo substituents; two are derivatives of (S)-2-ethanaminebenzimidazole; and the others are derivatives of one 2-(chloromethyl)-1H-benzo[d]imidazole and (1H-benzo[d]imidazol-2-yl)methanethiol. The results from the antifungal screening were also very interesting: 23 compounds exhibited potent fungicidal activity against the selected fungal strains. They displayed equivalent or greater potency in their MIC values than amphotericin B. The 5-halobenzimidazole derivatives could be considered promising broad-spectrum antimicrobial candidates that deserve further study for potential therapeutic applications.
PubMed | Sattam Bin Abdulaziz University, King Abdulaziz University and King Saud University
Type: Journal Article | Journal: Marine drugs | Year: 2016
Bioassay-guided fractionation of the organic extract of the Red Sea sponge Xestospongia testudinaria led to the isolation of 13 compounds including two new sterol esters, xestosterol palmitate (2) and xestosterol ester of l6-bromo-(7E,11E,l5E)-hexadeca-7,11,l5-triene-5,13-diynoic acid (4), together with eleven known compounds: xestosterol (1), xestosterol ester of 18-bromooctadeca-7E,9E-diene-7,15-diynoic acid (3), and the brominated acetylenic fatty acid derivatives, (5E,11E,15E,19E)-20-bromoeicosa-5,11,15,19-tetraene-9,17-diynoic acid (5), 18,18-dibromo-(9E)-octadeca-9,17-diene-5,7-diynoic acid (6), 18-bromooctadeca-(9E,17E)-diene-7,15-diynoic acid (7), 18-bromooctadeca-(9E,13E,17E)-triene-7,15-diynoic acid (8), l6-bromo (7E,11E,l5E)hexadeca-7,11,l5-triene-5,13-diynoic acid (9), 2-methylmaleimide-5-oxime (10), maleimide-5-oxime (11), tetillapyrone (12), and nortetillapyrone (13). The chemical structures of the isolated compounds were accomplished using one- and two-dimensional NMR, infrared and high-resolution electron impact mass spectroscopy (1D, 2D NMR, IR and HREIMS), and by comparison with the data of the known compounds. The total alcoholic and n-hexane extracts showed remarkable cytotoxic activity against human cervical cancer (HeLa), human hepatocellular carcinoma (HepG-2), and human medulloblastoma (Daoy) cancer cell lines. Interestingly, the dibrominated C18-acetylenic fatty acid (6) exhibited the most potent growth inhibitory activity against these cancer cell lines followed by Compounds 7 and 9. Apparently, the dibromination of the terminal olefinic moiety has an enhanced effect on the cytotoxic activity.
PubMed | Sattam Bin Abdulaziz University, Al - Azhar University of Egypt, King Saud University and Desert Research Center
Type: | Journal: Phytotherapy research : PTR | Year: 2017
Bio-guided fractionation of Aspergillus terreus extract leads to isolation of a novel terpenoidal secondary metabolite. The isolated compound and the total alcoholic extract of Aspergillus terreus showed a remarkable activity against microbial mouth infections; namely, Candida albicans, Lactobacillus acidophilus, Streptococcus gordonii, and S. mutan. Moreover, the Minimum Inhibitory Concentration of the isolated compound was determined and showed low values. The combination of each of the alcoholic extract of A. terreus and the isolated compound Coe-Comfort tissue conditioner inhibited the growth of Candida albicans at concentrations of 500 and 7.81g/mL, respectively, Lactobacillus acidophilus at concentrations of 250 and 7.81g/mL, respectively, Streptococcus gordonii at concentrations of 1000 and 62.50g/mL, respectively, and S. mutans at concentrations of 1000 and 125g/mL, respectively. The oral dosing of the extract and the isolated compound did not show any significant effect on the activity of alanine aminotransferase, aspirate aminotransferase, and the levels of blood urea and serum creatinine. Copyright 2017 John Wiley & Sons, Ltd.
PubMed | Sattam bin Abdulaziz University, King Saud University, University College of Applied Sciences and King Faisal Specialist Hospital And Research Center
Type: Journal Article | Journal: Radiation protection dosimetry | Year: 2015
Computed tomography (CT) scanning is recognised as a high-radiation dose modality and estimated to be 17 % of the radiological procedure and responsible for 70 % of medical radiation exposure. Although diagnostic X rays provide great benefits, their use involves some risk for developing cancer. The objectives of this study are to estimate radiation doses during chest, abdomen and pelvis CT. A total of 51 patients were examined for the evaluation of metastasis of a diagnosed primary tumour during 4 months. A calibrated CT machine from Siemens 64 slice was used. The mean age was 48.0 18.6 y. The mean patient weight was 73.8 16.1 kg. The mean dose-length product was 1493.8 392.1 mGy cm, Volume CT dose index (CTDI vol) was 22.94 5.64 mGy and the mean effective dose was 22.4 5.9 mSv per procedure. The radiation dose per procedure was higher as compared with previous studies. Therefore, the optimisation of patients radiation doses is required in order to reduce the radiation risk.