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591.
Khairy M. Hassan Mohamed S. K. Youssef Maher F. El-Zohry Raga Abo El-wafa 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):237-241
Abstract 2-Mercapto-3,5,7-triphenylpyrido[2,3-d]pyrimidine-4(3H)-one (II) was synthesized by the interaction of ethyl-2-amino-4,6-diphenylincotinate (I) with phenyl isothiocyanate in pyridine. The reaction of II with different reagents was carried out to give some condensed heterocyclic systems. 相似文献
592.
A comparative study of energy consumption and physical properties of microfibrillated cellulose produced by different processing methods 总被引:1,自引:0,他引:1
Kelley L. Spence Richard A. Venditti Orlando J. Rojas Youssef Habibi Joel J. Pawlak 《Cellulose (London, England)》2011,18(4):1097-1111
Microfibrillated celluloses (MFCs) with diameters predominantly in the range of 10–100 nm liberated from larger plant-based
fibers have garnered much attention for the use in composites, coatings, and films due to large specific surface areas, renewability,
and unique mechanical properties. Energy consumption during production is an important aspect in the determination of the
“green” nature of these MFC-based materials. Bleached and unbleached hardwood pulp samples were processed by homogenization,
microfluidization, and micro-grinding, to determine the effect of processing on microfibril and film properties, relative
to energy consumption. Processing with these different methods affected the specific surface area of the MFCs, and the film
characteristics such as opacity, roughness, density, water interaction properties, and tensile properties. Apparent film densities
were approximately 900 kg/m3 for all samples and the specific surface area of the processed materials ranged from approximately 30 to 70 m2/g for bleached hardwood and 50 to 110 m2/g for unbleached hardwood. The microfluidizer resulted in films with higher tensile indices than both micro-grinding and
homogenization (148 Nm/g vs. 105 Nm/g and 109 Nm/g, respectively for unbleached hardwood). Microfluidization and micro-grinding
resulted in films with higher toughness values than homogenization and required less energy to obtain these properties, offering
promise for producing MFC materials with lower energy input. It was also determined that a refining pretreatment required
for microfluidization or homogenization can be reduced or eliminated when producing MFCs with the micro-grinder. A summary
of the fiber and mechanical energy costs for different fibers and processing conditions with economic potential is presented. 相似文献
593.
J. Ben Youssef S. Pogossian D.T. Dekadjevi 《Journal of magnetism and magnetic materials》2010,322(17):2593-2595
The dependence of the coercive field and saturated magnetization on the interfacial width is studied to understand the driving mechanism of the coercive enhancement in Fe/Mn and Co/Mn bilayers. We establish a controlled annealing procedure to reveal the origin of this enhancement. Using a model, we reveal that the full interfacial width plays a keyrole, and that no Mn based finite size effects drive the mechanism. We show that this mechanism is common to both type of bilayers. 相似文献
594.
Abdelhalim Hafid Ahmed Taoufik Abella Bouaaddi Hassan Elouaddi Ahmed Tirbiyine Brahim Lmouden Mustapha Bghour Habiba El hamidi Youssef Ait Ahmed 《Chinese Journal of Physics (Taipei)》2018,56(2):754-759
In this paper, the critical current Jc(Θ) have been investigated as a function of magnetic-field angle Θ. Θ is the angle between the c-axis and the applied magnetic field direction. This investigation concerned three temperature values (60?K, 78?K and 81?K). The normalized pinning force fp versus the normalized magnetic field h was also studied (fp?=?Fp / Fpmax and h?=?H / Hmax). The Fp expression was determined based on the Kramer model.The studied sample was a single crystal of YBaCuO thin film deposited by the ablation laser method on the surface (100) of a SrTiO3 substrate.The results of this work show the existence of point core pinning of the normal centers in the low field regime and the occurrence of the flux creep in high field regime. 相似文献
595.
596.
Narendar Dudhipala Swetha Ettireddy Ahmed Adel Ali Youssef Goverdhan Puchchakayala 《Molecules (Basel, Switzerland)》2021,26(24)
Irbesartan (IR) is an angiotensin II receptor antagonist drug with antihypertensive activity. IR bioavailability is limited due to poor solubility and first-pass metabolism. The current investigation aimed to design, develop, and characterize the cyclodextrin(s) (CD) complexed IR (IR-CD) loaded solid lipid nanoparticles (IR-CD-SLNs) for enhanced solubility, sustained release behavior, and subsequently improved bioavailability through oral administration. Based on phase solubility studies, solid complexes were prepared by the coacervation followed by lyophilization method and characterized for drug content, inclusion efficiency, solubility, and in vitro dissolution. IR-CD inclusion complexes demonstrated enhancement of solubility and dissolution rate of IR. However, the dissolution efficiency was significantly increased with hydroxypropyl-βCD (HP-βCD) inclusion complex than beta-CD (βCD). SLNs were obtained by hot homogenization coupled with the ultrasonication method with IR/HP-βCD inclusion complex loaded into Dynasan 112 and glycerol monostearate (GMS). SLNs were evaluated for physicochemical characteristics, in vitro release, differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), and physical stability at room temperature for two months. The optimized SLNs formulation showed particle size, polydispersity index, zeta potential, assay, and entrapment efficiency of 257.6 ± 5.1 nm, 0.21 ± 0.03, −30.5 ± 4.1 mV, 99.8 ± 2.5, and 93.7 ± 2.5%, respectively. IR-CD-SLN and IR-SLN dispersions showed sustained release of IR compared to the IR-CD inclusion complexes. DSC results complimented PXRD results by the absence of IR endothermic peak. Optimized IR-CD complex, IR-SLN, and IR-CD-SLN formulations were stable for two months at room temperature. Thus, the current IR oral formulation may exhibit improved oral bioavailability and prolonged antihypertensive activity, which may improve therapeutic outcomes in the treatment of hypertension and heart failure. 相似文献
597.
Alexander Litvinenko Youssef Marzouk Hermann G. Matthies Marco Scavino Alessio Spantini 《Numerical Linear Algebra with Applications》2023,30(3):e2467
Very often, in the course of uncertainty quantification tasks or data analysis, one has to deal with high-dimensional random variables. Here the interest is mainly to compute characterizations like the entropy, the Kullback–Leibler divergence, more general -divergences, or other such characteristics based on the probability density. The density is often not available directly, and it is a computational challenge to just represent it in a numerically feasible fashion in case the dimension is even moderately large. It is an even stronger numerical challenge to then actually compute said characteristics in the high-dimensional case. In this regard it is proposed to approximate the discretized density in a compressed form, in particular by a low-rank tensor. This can alternatively be obtained from the corresponding probability characteristic function, or more general representations of the underlying random variable. The mentioned characterizations need point-wise functions like the logarithm. This normally rather trivial task becomes computationally difficult when the density is approximated in a compressed resp. low-rank tensor format, as the point values are not directly accessible. The computations become possible by considering the compressed data as an element of an associative, commutative algebra with an inner product, and using matrix algorithms to accomplish the mentioned tasks. The representation as a low-rank element of a high order tensor space allows to reduce the computational complexity and storage cost from exponential in the dimension to almost linear. 相似文献
598.
Ayman H. Kamel Nashwa H. Ashmawy Teraze A. Youssef Mostafa Elnakib Heba Abd El-Naby Hisham S. M. Abd-Rabboh 《Electroanalysis》2023,35(7):e202200436
Herein, two electrochemical methods based on potentiometric and impedimetric transductions were presented for albumin targeting, employing screen-printed platforms (SPEs) to make easy and cost-effective sensors with good detection merits. The SPEs incorporated ion-to-electron multi-walled carbon nanotubes (MWCNTs) transducer. Sensors were constructed using either tridodecyl methyl-ammonium chloride (TDMACl) (sensor I) or aliquate 336S (sensor II) in plasticized polymeric matrices of carboxylated poly (vinyl chloride) (PVC-COOH). Analytical performances of the sensors were evaluated using the above-mentioned electrochemical techniques. For potentiometric assay, constructed sensors responded to albumin with −81.7 ± 1.7 (r2 = 0.9986) and −146.2 ± 2.3 mV/decade (r2 = 0.9991) slopes over the linearity range 1.5 μM–1.5 mM with 0.8 and 1.0 μM detection limits for respective TDMAC- and aliquate-based sensors. Interference study showed apparent selectivity for both sensors. Impedimetric assays were performed at pH = 7.5 in 10 mM PBS buffer solution with a 0.02 M [Fe(CN)6]−3/−4 redox-active electrolyte. Sensors achieved detection limits of 4.3 × 10−8 and 1.8 × 10−7 M over the linear ranges of 5.2×10−8–1.0×10−4 M and 1.4×10−6–1.4×10−3 M, with 0.09 ± 0.004 and 0.168 ± 0.009 log Ω/decade slopes for sensors based on TDMAC and aliquate, respectively. These sensors are characterized with simple construction, high sensitivity and selectivity, fast response time, single-use, and cost-effectiveness. The methods were successfully applied to albumin assessment in different biological fluids. 相似文献
599.
600.