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Search Results: 1 - 10 of 537060 matches for " O. A. Yassin "
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Effect of the Cation Size Disorder at the A-Site on the Structural Properties of SrAFeTiO6 Double Perovskites (A = La, Pr or Nd)  [PDF]
Abdelrahman A. Elbadawi, O. A. Yassin, Mohamed A. Siddig
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.35003
Abstract: In this paper, the cation size disorder effect of the A-site on the structural properties of the SrAFe- TiO6 (A = La, Pr or Nd) was investigated. The compounds were synthesized—as the best of our knowledge—for the first time by conventional and precursor method to get crystalline materials. The results obtained from the experimental measurements carried out on new double perovskite materials were presented. The data of X-ray diffraction (XRD), Fourier Transform Infra Red FTIR were measured at room temperature. From the X-ray diffraction, and by means of standard Rietiveld method, all the samples have the same structure (orthorhombic) with Pnma space group. The difference in the tolerance factor is clearly noticed and refers to the cation size disorder at the A-sites. The Fourier Transform Infra Red FTIR measurement has been done; the results of it confirm the double perovskite structure and the difference between the samples were noticed. The tolerance factors for the samples altered from SrLaFeTiO6 up to SrNdFeTiO6 and this difference return to ionic radius and cation size effect.
Downregulation of transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) in ehrlich ascites carcinoma-bearing mice using stearic acid-grafted carboxymethyl chitosan (SA-CMC)  [PDF]
Salem A. Habib, Yassin A. Aggour, Hossam A. Taha
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.411108
Abstract: The present study was conducted to investigate the use of stearic acid-grafted carboxymethyl chitosan(SA-CMC) as a downregulator for trans- forming growth factor-β (TGF- β) and vascular endothelial growth factor (VEGF) in Ehrlich ascites carcinoma (EAC)-bearing mice. The antitumor effect of stearic acid-grafted carboxymethyl chitosan was assessed by the estimation of TGF- β and VEGF in serum in addition to the estimation of tumor volume, median survival time (MST), percentage of increase in life span (ILS%) as well as the contents of total lipid, DNA and RNA in liver tissues. Hematological profiles (hemoglobin, red blood cells, and platelets) were also assessed. In addition, liver function tests and the redox status were estimated. TGF- β, VEGF, DNA, RNA, and malondialdehyde (MDA) levels, in addition to serum alanine transaminase (ALT) and gamma glutamyl transferase (GGT) activities as well as total white blood cells counts and tumor volume were all highly significantly increased (P < 0.001) in untreated EAC-bearing mice compared to controls. However, hematological profiles, total lipid in liver tissues and serum albumin were highly decreased in EAC-bearing mice compared to controls. All these parameters were restored to the normal levels in SA-CMC treated EAC-bearing mice com- pared to the untreated EAC-bearing mice. It is thus concluded that stearic acid-grafted carboxymethyl chitosan has a remarkable antitumor activity against EAC in Swiss albino mice through downregulation of TGF-β and VEGF.
Assessment of the Sensitivity of Streamflow Simulations to Changes in Patch Resolution Using GIS Based Hydro-Ecologic Model  [PDF]
Samson G. Mengistu, Melkamu A. Ali, Fuad A. Yassin
Open Journal of Modern Hydrology (OJMH) , 2016, DOI: 10.4236/ojmh.2016.62007
Abstract: Eight different patch configurations were investigated to analyze the effect of patch characterization/formation in streamflow simulation, using the Regional Hydro-Ecologic Simulation Systems (RHESSys) model. It is investigated for eight different patch configurations of a subcatchment of the Turkey Lakes Watershed, Ontario. The model’s hydrological parameters are calibrated for each of these patch configurations and the performance of the simulations is evaluated. Results indicate that both the nature of the flow simulation and the calibrated parameter values are sensitive to patch configuration. The best simulation results were obtained for the patch configuration with the highest spatial variation of climate, stream network and hillslope conditions across the subcatchment. Different patch configurations also lead to markedly different calibrations of the model’s hydrological parameters (54.26 < k < 119.13; and 1.02 < m < 2.28), which has implications for the physical interpretation and transferability of the calibrated parameter values.
Outcome and Complications of Colonoscopy: A Prospective Multicenter Study in Northern Israel
A. Suissa,O. S. Bentur,J. Lachter,K. Yassin,I. Chermesh,I. Gralnek,A. Karban,I. Khamaysi,Y. Naveh,A. Tamir,A. Shahbari,R. Eliakim
Diagnostic and Therapeutic Endoscopy , 2012, DOI: 10.1155/2012/612542
Abstract: Background. Colonoscopy for screening the population at an average risk of colorectal cancer (CRC) is recommended by many leading gastrointestinal associations. Objectives. The objective was to assess the quality, complications and acceptance rate of colonoscopy by patients. Methods. We prospectively gathered data from colonoscopies which were performed between October 2003 and September 2006. Patients were asked to return a follow-up form seven days after the procedure. Those who failed to do so were contacted by phone. Results. 6584 patients were included (50.4% males). The average age of subjects was 57.73 (SD 15.22). CRC screening was the main indication in 12.8%. Cecal intubation was achieved in 92% of patients and bowel preparation was good to excellent in 76.2%. The immediate outcome after colonoscopy was good in 99.4%. Perforations occurred in 3 cases—1 in every 2200 colonoscopies. Significant bleeding occurred in 3 cases (treated conservatively). 94.2% of patients agreed to undergo repeat colonoscopy in the future if indicated. Conclusions. The good quality of examinations, coupled with the low risk for complications and the good acceptance by the patients, encourages us to recommend colonoscopy as a primary screening test for CRC in Israel. 1. Background In recent decades, colonoscopy has been established worldwide as the “gold standard” common procedure for the evaluation of the colon. Indications for colonoscopy include examining symptomatic individuals, performing followup on patients with colonic diseases and screening of healthy individuals for CRC. After lung cancer, CRC is the second most common cause of cancer-related death in the United States [1]. In Israel, CRC is the second most common malignancy in men and women with an annual occurrence of about 3000 new patients per year [2]. The precancerous lesion, the adenomatous polyp, progresses to CRC over a period of 4 to 12 years, therefore there is a golden opportunity for early detection as well as primary prevention by removing polyps. 5-year survival rates in CRC patients diagnosed early are over 90%, whereas they drop to under 10% when disease is diagnosed in advanced stages. Hence, CRC fulfills the criteria of a disease in which screening is highly efficient: high occurrence, long latent period, and an improved prognosis with early detection [3, 4]. An additional efficiency criterion fulfilled by this disease is the availability of efficient and cost-effective tests. The American Gastroenterological Association, The American College of Gastroenterology, and the American Society for
Yield of Smear Microscopy and Radiological Findings of Male and Female Patients with Tuberculosis in Abuja, Nigeria
Lovett Lawson,Mohammed A. Yassin,Alex N. Onuoha,Andrew Ramsay,Rachel R. M. Anderson de Cuevas,Sally Theobald,Peter D. O. Davies,Luis E. Cuevas
Tuberculosis Research and Treatment , 2010, DOI: 10.1155/2010/241659
Abstract: Objective. To describe the yield of smear-microscopy and radiological findings by male and female patients with symptoms of tuberculosis in Abuja, Nigeria. Methods. Patients ≥15 years old with cough for >3 weeks submitted 3 sputum samples for smear microscopy. One specimen was cultured using MGIT-960. All patients had lung X-rays and screened for HIV. Results. were more likely to be smear-positive than females (262/774 [34%] and 137/547 [25%], <.01), but similar proportions of males and females were culture-positive (437/691 [63%] and 294/495 [59%], =.09). 317/626 (50.6%) males and 249/419 (59.4%) females were HIV-positive (<.005). Among culture-positives patients, HIV-infected males were less likely to have positive smears than HIV-negative males (49.2% versus 66%, =.001). Among females, smear positivity did not vary with HIV (46.4% for HIV-positive and 52.9% for HIV-negative, =.38). Of 274 culture-confirmed TB cases, 226 (82.5%) had cavities, and 271 (99%) had ≥1 lung areas affected. HIV-positive males were more likely to have lung cavities than HIV-positive females (85% versus 69%, <.04) and to have ≥3 lung areas affected (=.03). Conclusion. Differences in the yield of smear-microscopy, culture and X-rays on presentation are due to several factors including HIV coinfection and gender.
Surface Modification of Waste Tire by Grafting with Styrene and Maleic Anhydride  [PDF]
Yassin A. Aggour, Ayed S. Al-Shihri, Mohamed R. Bazzt
Open Journal of Polymer Chemistry (OJPChem) , 2012, DOI: 10.4236/ojpchem.2012.22009
Abstract: Waste tire powder, as waste rubber WR was subjected to grafting with styrene (St) and maleic anhydride (MA). Hydrogen peroxide H2O2 was used to initiate the free radical copolymerization of St onto WR. A thermal initiation was used in case of grafting of MA onto WR. Effect of initiator and monomer concentrations together with the influence of reaction temperature and reaction time were investigated. The grafting was estimated by weight, and the grafted copolymers were characterized by FT/IR, DSC and SEM to prove the grafting. It has found that the grafting increases with increase monomer and initiator concentrations. The increase in the reaction temperature and time also causes increasing levels of the grafted St and MA.
Removal of Cr(VI) from Aqueous Solution Using Modified Pomegranate Peel : Equilibrium and Kinetic Studies
Tariq S. Najim,Suhad A. Yassin
Journal of Chemistry , 2009, DOI: 10.1155/2009/936541
Removal of Chromium from Aqueous Solution Using Modified Pomegranate Peel:Mechanistic and Thermodynamic Studies
Tariq S. Najim,Suhad A. Yassin
Journal of Chemistry , 2009, DOI: 10.1155/2009/804256
Chemical Modification of Scraped Tires through Grafting with 2-Acrylamido-2-methylpropansulfonic Acid  [PDF]
Yassin A. Aggour, Ayied S. Al-Shihri, Mohamed R. Bazzet
Open Journal of Polymer Chemistry (OJPChem) , 2013, DOI: 10.4236/ojpchem.2013.33010

Scrap vulcanized rubber is amongst a bigger waste polymers. It does not decompose easily owing to its cross linked structure. Modification of scrap tires powder by the grafting with 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is described. The grafting is achieved through free radical initiation. The effects of different amount of monomer and initiator were examined. Also the influence of reaction time and temperature were investigated. The grafted waste rubber was characterized by FT/IR, SEM and DSC measurements. The proposed mechanism of the grafting reaction is discussed. From DSC and SEM studies of WR-g-AMPS compared with PAMPS and WR, the results show that the particle size and crystallinity were enhanced for the grafted copolymers. The obtained modified scraped tires will used as an ion exchanger for the future applications.

Climate Characteristics over Southern Highlands Tanzania  [PDF]
Yassin Mbululo, Fatuma Nyihirani
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.24039
Abstract: This study was conducted to examine the climate characteristic of southern highland Tanzania (Latitude 6°S-12°S and Longitude 29°E-38°E). The study findings reveal that rainfall over the region is linked with SST over the Indian Ocean, where warmer (cooler) western Indian Ocean is accompanied by high (low) amount of rainfall over Tanzania. During wet (dry) years, weaker (stronger) equatorial westerlies and anticyclone (cyclonic) anomaly over the southern tropics act to reduce (enhance) the export of equatorial moisture away from East Africa. The wettest (driest) season was found to be 1978/79 (1999/00) which can be classified as the severely wet (moderate drought). Two different modes of rainfall have been identified at time scale of 1.5 and 6 years which have been associated with the quasi biennial oscillation (QBO) and El Nino Southern Oscillation (ENSO), respectively.
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