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991.
We derive a quantum-corrected hydrodynamic and drift-diffusion model for the out-of-equilibrium particle dynamics in the presence of particle collisions, modeled by a BGK collision term. The quantum mechanical corrections are obtained within the Liouville formalism and are expressed by an effective nonlinear force. The Boltzmann and Fermi-Dirac statistics are included. 相似文献
992.
Ludmila C. Fidale Paulo M. Lima Jr. Lucas M. A. Hortêncio Paulo A. R. Pires Thomas Heinze Omar A. El Seoud 《Cellulose (London, England)》2012,19(1):151-159
The properties of films of carboxymethyl cellulose, CMC, of different degree of substitution, DS, have been examined by the
use of perichromic indicators (probes). The film properties that have been determined are: empirical polarity, ET(33); “acidity”, α; “basicity”, β; and dipolarity/polarizability, π*. This has been achieved by employing the following perichromic
probes: 4-nitroaniline, 4-nitroanisole, 4-nitro-N,N-dimethylaniline, and 2,6-dichloro-4-(2,4,6-triphenyl-pyridinium-1-yl)phenolate, WB. The correlations between both ET(33)- or π* and DS were found to be linear; that between β and DS is a second order polynomial; no obvious correlation was
found between α and DS. The polarities of CMC films are in the range of those of butyl alcohols. As models for CMC, we have
employed cellulose plus CMC of high DS; oxidized cellulose with degree of oxidation = 0.5; sodium glucuronate. The former
model behaved akin to CMC, but the plots of the perichromic properties versus DS showed different slopes/intercepts. FTIR
data and molecular dynamics simulations on the solvation of WB have shown that this difference can be traced to more efficient
hydrogen bonding between the film of the model and the probe. This affects the intra-molecular charge-transfer energy of the
latter, leading to different responses to the variation of DS. Based on the excellent linear correlation between ET(33) and DS, for CMC from different origins, we suggest that perichromism is a simple, accurate, and expedient alternative
for the determination of DS of the biopolymer derivative. 相似文献
993.
Dr. Sally E. A. Elashery Prof. Dr. Nour F. Attia Gehad G. Mohamed M. M. Omar Hager M. I. Tayea 《Electroanalysis》2021,33(11):2361-2371
A potentiometric sensor modified with a nanocomposite of montmorillonite sheets decorated with polyaniline nanofibers (MT-PANI-NFs) as an efficient electroactive material and tricresyl phosphate (TCP) as a solvent mediator has been developed for the estimation of clomipramine HCl (CLP.HCl). The optimum potentiometric performance of the sensor was achieved by mixing of MT-PANI-NFs : TCP : graphene with a ratio of 2.69 : 30.11 : 67.20 (% wt/wt). The sensor exhibited a Nernstian slope of 59.0±0.1 mV decade−1 over the concentration range of 1.0×10−5−1.0×10−2 mol L−1 with a theoretically calculated detection limit of 5.0×10−6 mol L−1. The sensor performance was scrutinized in terms of several factors including thermal stability, pH effect, response time and selectivity. As, it displayed a high thermal stability at various temperature degrees (10–60 °C) with pH independency in the range of 3.5–8.5. Additionally, the developed sensor exhibited a very rapid performance for CLP.HCl detection with a fast response time of 4 s and reflecting a superior selectivity towards CLP.HCl over the other interfering species. SEM (scanning electron microscope) was used as a characteristic tool for the investigation of the proposed graphene sensor surface. Furthermore, the graphene sensor has been efficiently used for CLP.HCl estimation in its pharmaceutical formulations. 相似文献
994.
Novel fluorescent coumarin-4H-pyran conjugates were achieved by three-component reactions of various synthetic β-ketoesters with aldehydes and malononitrile in aqueous media.Besides mild reaction conditions,operational simplicity,absence of tedious separation procedures,using of inexpensive and nontoxic commercially available cationic surfactant cetyltrimethylammonium chloride(CTAC) as a catalyst are the prominent advantage of this method. 相似文献
995.
Omar Tout 《Journal of Algebraic Combinatorics》2017,45(4):1111-1152
In this paper, we build a general framework in which we give a formula that shows the form of the structure coefficients of double-class algebras and centers of group algebras. This formula allows us to give a polynomiality property for the structure coefficients of some important algebras. In particular, we re-obtain the polynomiality property of the structure coefficients in the cases of the center of the symmetric group algebra and the Hecke algebra of the pair \((\mathcal {S}_{2n},\mathcal {B}_{n}).\) We also assign a new polynomiality property for the structure coefficients of the center of the hyperoctahedral group algebra and the Hecke algebra of the pair \((\mathcal {S}_n\times \mathcal {S}_{n-1}^\mathrm{opp},{{\mathrm{diag}}}(\mathcal {S}_{n-1}))\). 相似文献
996.
Omar Castillo-Aguilera Patrick Depreux Ludovic Halby Nathalie Azaroual Paola B. Arimondo Laurence Goossens 《Tetrahedron letters》2017,58(26):2537-2541
Substituted heterocycles, such as pyrrole and thiophene, are commonly found in the field of pharmaceutical and material sciences. Here we studied the reactivity of 4,5-unsubstituted alkyl 3-hydroxypyrrol-2-yl-carboxylates and 4,5-unsubstituted alkyl 3-hydroxythiophen-2-yl-carboxylates in different halogenation conditions, due to their interest as building blocks in the synthesis of bioactive compounds and materials. We describe herein the regioselective monohalogenation of 3-hydroxypyrroles and 3-hydroxythiophenes in mild conditions with common halogenation agents. The selectivity of the halogenation was studied. Optimized one-step reaction conditions were found for monobromination and monochlorination. Finally, we observed that bromination with N-bromosuccinimide (NBS) took place at the C4 position of the heterocycle, while chlorination with SO2Cl2 led to C5-halogenated derivatives. 相似文献
997.
We determine the complex-valued solutions of the following extension of the Cosine–Sine functional equation where S is a semigroup generated by its squares and \(\sigma \) is an involutive automorphism of S. We express the solutions in terms of multiplicative and additive functions.
相似文献
$$\begin{aligned} f(x\sigma (y))=f(x)g(y)+g(x)f(y)+h(x)h(y),\quad x,y\in S, \end{aligned}$$
998.
S. A. Abdulateef A. F. Omar M. Z. Mat Jafri Naser M. Ahmed Azman Seeni 《Journal of Cluster Science》2017,28(6):3193-3207
In saline solutions with NaCl concentrations less than that typical of blood plasma and bodily fluids, gold nanoparticles (GNPs) aggregate and precipitate because of GNP cation complexation with the Cl? anions in the solution. It is difficult to retain stable colloidal GNPs within any saline solution for a relatively long time without aggregation and precipitation. In this study, we developed a method to synthesize stable GNPs in harsh anion-containing environments. GNPs were formed by laser ablation in a saline solution, and their stabilization was achieved by adding bovine serum albumin (BSA) to the NaCl solution; this has been shown to be a quick, efficient approach to producing stable colloidal GNPs. GNP nanoclusters in saline solutions with and without BSA were observed via high-resolution transmission electron microscopy and selected area electron diffraction. The results reveal that our methodology yields colloidal GNPs with long-term stability in a BSA-containing saline solution. 相似文献
999.
Muhammad Sajjad Ahmad Muhammad Aamer Mehmood Guangbin Ye Omar S. Al-Ayed Muhammad Ibrahim Umer Rashid Huibo Luo Ghulam Qadir Imededdine Arbi Nehdi 《Journal of Thermal Analysis and Calorimetry》2017,130(3):1237-1247
The present study was focused on the thermal degradation of Eulaliopsis binata biomass produced on a salt-affected soil without any fertilizer or pesticide applications. The plant biomass was subjected to thermal degradation experiments at three heating rates, 10, 30 and 50 K min?1. The kinetic analyses were performed through isoconversional models of Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa, followed by the calculation of thermodynamic parameters of activation. The high heating value was calculated as 15.10 MJ mol?1. The activation energy values of the grass were shown to be ranging from 118 through 240 kJ mol?1. Energy difference of enthalpies of activation between the reagent and the activated complex was in accordance with activation energies. Pre-exponential factors indicated the reaction to follow first-order kinetics. Gibbs free energy for the grass was measured to be ranging from 171 to 174 kJ mol?1. Our data have shown that E. binata biomass offers remarkable potential as a low-cost biomass for bioenergy. 相似文献
1000.
Concurrent Stabilization of π‐Donor and π‐Acceptor Ligands in Aromatized and Dearomatized Pincer [(PNN)Re(CO)(O)2] Complexes 下载免费PDF全文
Michael G. Mazzotta Dr. Kothanda Rama Pichaandi Dr. Phillip E. Fanwick Prof. Dr. Mahdi M. Abu‐Omar 《Angewandte Chemie (International ed. in English)》2014,53(32):8320-8322
Aromatized cationic [(PNN)Re(π acid)(O)2]+ ( 1 ) and dearomatized neutral [(PNN*)Re(π acid)(O)2] ( 2 ) complexes (where π acid=CO ( a ), tBuNC ( b ), or (2,6‐Me2)PhNC ( c )), possessing both π‐donor and π‐acceptor ligands, have been synthesized and fully characterized. Reaction of [(PNN)Re(O)2]+ ( 4 ) with lithiumhexamethyldisilazide (LiHMDS) yield the dearomatized [(PNN*)Re(O)2] ( 3 ). Complexes 1 and 2 are prepared from the reaction of 4 and 3 , respectively, with CO or isocyanides. Single‐crystal X‐ray structures of 1 a and 1 b show the expected trans‐dioxo structure, in which the oxo ligands occupy the axial positions and the π‐acidic ligand occupies the equatorial plane in an overall octahedral geometry about the rhenium(V) center. DFT studies revealed the stability of complexes 1 and 2 arises from a π‐backbonding interaction between the dxy orbital of rhenium, the π orbital of the oxo ligands, and the π* orbital of CO/isocyanide. 相似文献