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Variable range hopping conduction in n-CdSe samples at very low temperature

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Journal of Semiconductors 2015年第12期36卷 14-17页

作者： m Errai A el Kaaouachi H el Idrissi Physics Department Ibn Zohr University Faculty of Sciences Laboratoire electronique électrotechnique Automatique et Traitement de l'Information Département Génie ElectriqueFaculté des Sciences et Techniques de Mohammedia Université Hassan Ⅱ Mohammedia Casablanca

We reanalyzed experimental data already published in Friedman J R, Zhang Y, Dai P, et al. Phys Rev B, 1996, 53（15）： 9528. Variable range hopping （VRH） conduction in the insulating three-dimensional n-CdSe samples has been studied over the entire temperature range from 0.03 to 1 K. In the absence of a magnetic field, the low temperature conductivity a of the three samples （A, B and C） obeys the mott VRH conduction with an appropriate temperature dependence in the prefactor （a = σ0 exp [- （T0/T）]^p with p ≈ 0.25）. This behavior can be explained by a VRH model where the transport occurs by hopping between localized states in the vicinity of the Fermi level, EF, without creation of the Coulomb gap （CG）. On the contrary, no Efros-Shklovskii VRH is observed, suggesting that the density is constant in the vicinity of the EF.

关键词： n-CdSe samples low temperature variable range hopping density of state

Long-term changes in sea surface temperature(SST)within the southern Levantine Basin

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Acta Oceanologica Sinica 2021年第3期40卷 27-33页

作者： Tarek m.el-Geziry Laboratory of Physical Oceanography Division of Marine EnvironmentNational Institute of Oceanography and Fisheries(NIOF)Alexandria21556Egypt

Knowledge of sea surface temperature(SST)behaviour is vital for long-term climate *** study highlights essential outcomes about the distinguishable and unsurprising warming of the SST along the southern border of the Levantine *** analysis is based on monthly SST data for the period *** southern Levantine Basin has undergone SST increase,during the last 71 *** this study,a consistent warming trend has been found for the analysed SST data series,with a rate of 0.04℃/a,i.e.,0.4℃/(10 a).From 1975 to 1991 the mean annual SST was 17.1℃,and this increased to be 19.2℃,over the period *** revealed two opposite trends of variability:a decreasing trend(−0.06℃/a)over the period 1975-1991,and an increasing trend(0.2℃/a)from 2002 to *** the period 1948-2018,positive mean annual SST anomalies had an average of 1.8℃,and negative anomalies had an average of−1.1℃.The lowest SST total increase was found from January to April,with values about 0.03℃,while the highest warming appeared from June to *** driving mechanisms behind the SST changes need to be more investigated,to understand the future trends and impacts of climate change in the Levantine Basin.

关键词： mediterranean Sea Levantine Basin sea surface temperature anomaly trends warming

Calponin 3 promotes invasion and drug resistance of colon cancer cells

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World Journal of Gastrointestinal Oncology 2019年第11期11卷 971-982页

作者： Vidhya A Nair Noura A Al-khayyal Sivaramakrishnan Sivaperumal wael m Abdel-Rahman Environment and Cancer Research Group Sharjah Institute for Medical ResearchUniversity of SharjahSharjah 27272United Arab Emirates College of medicine and Sharjah Institute for medical Research University of SharjahSharjah 27272United Arab Emirates Department of Biotechnology Bharathidasan UniversityTiruchirappalli 620024India Department of medical Laboratory Sciences College of Health Sciences and Environment and Cancer Research GroupSharjah Institute for Medical ResearchUniversity of SharjahSharjah 27272United Arab Emirates

BACKGROUND Calponin 3(CNN3)is an actin-binding protein expressed in smooth muscle and non-smooth muscle *** is required for cytoskeletal rearrangement and wound *** To dissect the role of CNN3 in carcinogenesis with a focus on colon *** A total of 20 cancer cell lines(8 breast,11 colon,and Hela cervical cancer cell as a positive control for mesenchymal phenotype)and 57 formalin-fixed,paraffinembedded sections from archived sporadic colorectal carcinomas were included in this ***3 expression analysis by western blot or immunohistochemistry was followed by functional *** CNN3 gene was silenced by specific small interfering RNA(commonly known as siRNA),followed by confirmation of the silencing efficiency by western ***,the silenced cells and control siRNA-transfected cells were analyzed for changes in epithelial and mesenchymal markers,invasion,and response to 5-fluoruracil *** also performed proteomics analysis using a phospho-kinase array-based panel of 45 *** CNN3 showed positive expression in 6/8 breast and 9/11 colon cancer lines and in Hela ***,the colorectal adenocarcinoma line SW480 was negative,while the cell line developed from its matching lymph node metastasis(SW620)was positive for ***3 expression was fairly consistent with the metastatic phenotype in colon cancer because it was absent in one other colon cell line from a primary site and expressed in all *** selected SW620 for subsequent functional ***3-silenced SW620 cells showed a reduction in collagen invasion and loss of mesenchymal ***3 silencing caused an increase in the SW620 colon cancer cell sensitivity to *** array-based proteomics analysis showed that CNN3 silencing in SW620 reduced extracellular signal-regulated kinase,β-Catenin,mutant p53,c-Jun,and heat shock protein 60 activities but increased that of checkpoint kinase ***3 was expressed in 20/57(35%)co

关键词： β-Catenin Calponin 3 Colon cancer Epithelial-mesenchymal transition Invasion metastasis

Yttria Tetragonal Zirconia Biomaterials:Kinetic Investigation

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Journal of materials Science & Technology 2011年第4期27卷 332-337页

作者： Ezzat S.elshazly S.m.el-Hout m.el-Sayed Ali Department of mechanical Engineering Virginia Commonwealth University Deptartment of metallurgy Nuclear Research CenterAtomic Energy Authority

The low temperature aging behavior of polycrystalline tetragonal zirconia was investigated to explore the effects on phase transformation occurring during the process. XRD analysis was conducted for the phase identification and the tetragonal to monoclinic phase transformation was determined. The aging of tetragonal zirconia polycrystals doped with 3 mol% Y203 triggers tetragonal to monoclinic phase transformation on the surface of the specimen only, while the penetration inside the bulk of the specimen is very limited. A slight decrease in the mechanical properties was also observed after aging for 40 h. The transformation kinetics show a nucleation and growth mechanism on the specimen surface to be dominant in the low temperature aging in water environment.

关键词： Low temperature degradation 3Y-TZP Kinetics

Thiolsulfonate functionalized polystyrene resin:Preparation and application in the isolation and identification of electrophilic mutagens

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Journal of Environmental Sciences 2007年第12期19卷 1520-1527页

作者： Wu el Robert m. Carlson Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Department of Chemistry University of Minnesota-Duluth Duluth MN 55812 USA

A new approach for isolation and identification of elecrtophilic mutagens from complex matrix was developed. Thiosulforfic anion was immobilized onto polystyrene beads and used as separation media. Potassium polystyryl-thiosulfonate, prepared from polystyryl- sulfonyl chloride and KHS, was observed to selectively react with model electrophilic mutagens such as alkyl halides, ct-chloroketones and α-chloroesters to produce polystyryl-thiosulfonlc esters. After separation from other nonreactive organic compounds, the beads then reacted with ethanethiol to produce unsymmetrical ethyl disulfides which are easily detected by GC/mS. For one mutagenic compound, only one unsymmetrical disulfide was found to contain its structure part. Thus, the structure of the parent mutagens could be deduced from that of the unsymmetrical disulfides. The degree of functionalization of the potassium polystyryl-thiosulfonate resin was 1.11 mmol/g. Its reactivity was discussed and its recycling method was reported here.

关键词： functionalized polystyrene potassium polystyryl-thiosulfonate unsymmetrical ethyl disulfides electrophilic mutagens

Processing of Ceramic Based Nanocomposite Usingα-Al_2O_3 Powder and FeCl_2 Solution as Starting materials

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Journal of materials Science & Technology 2007年第6期23卷 837-842页

作者： mohamed m.el-Sayed Seleman Department of materials and metallurgical Engineering Faculty of Petroleum and Mining EngineeringPost Code 43721SuezEgypt

Alumina-iron nanocomposite powders were prepared by a two-step process. In the first step, α-Al2O3-FeCl2 powder mixture was formed by mixing α-Al2O3 powders with FeCl2 solution followed by drying. In the second step, the FeCl2 in the dry power mixture was selectively reduced to iron particles. A reduction temperature of 750℃ for 15 min in dry H2 was chosen based on the thermodynamic calculations. The concentration of iron in FeCl2 solution was calculated to be 20 vol. pct in the final composite. Two techniques were used to produce composite bulk materials. The Al2O3 nanocomposite powders were divided to two batches. The first batch of the produced mixture was hot pressed at 1400℃ and 27 mPa for 30 min in a graphite die. To study the effect of oxygen on the Al2O3/Fe interface bonding and mechanical properties of the composite, the second batch was heat treated in air at 700℃ for 20 min to partially oxidize the iron particles before hot pressing. Characterization of the composites was undertaken by conventional density measurements, X-ray diffractometry （XRD）, scanning electron microscopy （SEm）, transmission electron microscopy （TEm） and electron probe micro analysis （EPmA）. The suggested processing route （mixing, reduction and hot pressing） produces ceramic-metal nanocomposite much tougher than the pure Al2O3. The fracture strength of the produced Al2O3/Fe nanocomposite is nearly twice that of the pure Al2O3. The presence of spinel phase, FeAl204, as thick layer around the Fe particles in the Al2O3 matrix has a detrimental effect on interfacial bonding between Fe and AI203 and the fracture properties of the composite.

关键词： Ferrous chloride Reduction Alumina-iron nanocomposite Spinel phase

2D CFD Analysis and Experimental Analysis on the Effect of Hub to Tip Ratios on the Performance of 0.6 m Impulse Turbine

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Journal of Thermal Science 2004年第4期13卷 315-320页

作者： A. THAKKER m.el. HEmRY Wave Energy Research Team Department of mechanical and Aeronautical Engineering University of Limerick IrelandWave Energy Research Team Department of Mechanical and Aeronautical Engineering University of Limerick Ireland

The objective of this paper is to present the performance comparison of 2D Computational Fluid Dynamics (CFD) analysis with experimental analysis of 0.6 m impulse turbine with fixed guide vanes for both 0.6 and 0.7 hub to tip ratio (H/T). Also the comparison of 2D CFD analysis of the said turbine with different values of H/T ranging from 0.5 to 0.7. A 2D-cascade model was used for CFD analysis while uni-directional steady flow was used for experimental analysis. The blade and guide vane geometries are based on 0.6 m rotor diameter, with optimum profile, and different H/T of 0.5, 0.6 and 0.7. It was concluded from 2D CFD analysis that 0.5 H/T ratio performances was higher than that of 0.6 and 0.7 H/T at peak efficiency and the operational flow range for 0.5 H/T was found to be wider than that of 0.6 and 0.7 H/T ratio.

关键词： wave energy impulse turbine computational fluid dynamics (CFD).

FIRST-ORDER mETHODS FOR SOLVING THE OPTImAL STATIC H∞-SYNTHESIS PROBLEm

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Journal of Computational mathematics 2007年第6期25卷 672-689页

作者： el-Sayed m.E. mostafa Department of mathematics Faculty of Science Alexandria University Alexandria Egypt

In this paper, we consider the static output feedback （SOF） H∞-synthesis problem posed as a nonlinear semi-definite programming （NSDP） problem. Two numerical algorithms are developed to tackle the NSDP problem by solving the corresponding Karush- Kuhn-Tucker first-order necessary optimality conditions iteratively. Numerical results for various benchmark problems illustrating the performance of the proposed methods are given.

关键词： Static output feedback H∞-synthesis Semi-definite programming Nonlinear programming.

Effects of Nickel Distribution on the Strengthening and Toughening of Alumina Ceramics

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Journal of materials Science & Technology 2008年第5期24卷 723-728页

作者： mohamed.m.el-Sayed Seleman Department of materials and metallurgical Eng. Faculty of Petroleum and Mining Eng.Post Code 43721SuezEgypt

Three types of composite materials were designed and fabricated by hot pressing powder blends of alumina with 20 vol. pct nickel particles. The composites differ in the shape, size and distribution of the nickel particles. Composite microstructures are described and measurements of density, hardness, flexure strength, and fracture toughness are reported. The results showed that the fracture strength of the composite with dispersed nickel particles is higher than the other two composites （network microstructure and mixed microstructure） and the alumina matrix. For all the composites studied, tougher materials than the monolithic alumina were produced. The fracture toughness of the composite with a network microstructure is much higher than that of the other composites. The toughening mechanisms were described based on the observation of the fracture surfaces and the crack-particle interactions. moreover, the parameters for microstructural tailoring of these materials have been deduced. The toughening of the produced composites was explained in light of the interracial bond strength.

关键词： Alumina-nickel composites Nickel morphology Interfacial bonding Fracturetoughness Flexure strength