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排序方式: 共有266条查询结果,搜索用时 15 毫秒
1.
Yusuf Musa Malcolm P. Stevens 《Journal of polymer science. Part A, Polymer chemistry》1972,10(2):319-327
Polyimides have been synthesized by the sensitized photoaddition of aliphatic and aromatic bismaleimides to benzene. The reaction involves 2+2 cycloaddition to give homoannular diene intermediate followed by Diels-Alder addition to give polymer. Proof of structure is based mainly on a comparison of infrared spectra with those of the corresponding polyimides prepared from maleic anhydride-benzene photoadduct and diamines. The very low solubility of the polymers indicates that crosslinking probably occurred during photolysis. All the polyimides appear to decompose by decyclization at about 420–485°C. Polymer yield was dependent on bismaleimide structure. 相似文献
2.
Shongwe MS Kaschula CH Adsetts MS Ainscough EW Brodie AM Morris MJ 《Inorganic chemistry》2005,44(9):3070-3079
Three mononuclear ternary complexes of iron(III) with an alpha-diimine (bipy or phen) and a derivative of N,N-bis(2-hydroxybenzyl)glycinate (L3-) have been synthesized and characterized by magnetic susceptibility measurements, electron paramagnetic resonance (EPR) spectroscopy, vibrational spectroscopy, and electronic absorption spectroscopy. Single-crystal X-ray structure determinations of the pseudo-octahedral complexes [Fe(bipy)L] x MeCN [L = (3,5-Br2)-L3- or (5,3-Cl,Me)-L3-] revealed a considerable and consistent distortion in the coordination of bipy to iron(III) attributable largely to electronic effects. In both crystal structures, the Fe-N(pyridyl) bond trans to the phenolate oxygen is 0.133 A longer than the other one positioned trans to the tertiary amine nitrogen, a relatively weaker donor. This coordination behavior of bipy is of structural interest and has not been observed previously for iron(III). The electronic and EPR spectra of the compounds [Fe(L'-L')L] x MeCN (L'-L' = bipy or phen) are consistent with the spin state of the central metal atom (S = 5/2). The charge-transfer transitions arising from the strong interactions of the phenolate moieties with the ferric ion have been identified as phenolate (p(pi)) --> iron(III) (d(pi*)) (lambda(max) approximately 500 nm, epsilon approximately 3000 M(-1) cm(-1)) and phenolate (p(pi)) --> iron(III) (d(sigma*) (lambda(max) approximately 320 nm, epsilon approximately 5200 M(-1) cm(-1)). The presence of the phenolate moieties in the quadridentate hetero-donor tripodal ligands, H3L, lends these iron(III) ternary complexes the potential to model the specific metal-coordination, metal-substrate interactions, and physicochemical behaviors of several iron-tyrosinate proteins. 相似文献
3.
Bandar Ali Al-Asbahi Mohamad S. AlSalhi Mohammad Hafizuddin Hj. Jumali Amanullah Fatehmulla Saif M. H. Qaid Wafa Musa Mujamammi Hamid M. Ghaithan 《Molecules (Basel, Switzerland)》2022,27(20)
The improvement of optical and optoelectronic properties of the individual poly [2-methoxy-5- (2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene]–End capped with Dimethyl phenyl (OC1C10–PPV–DMP), and poly (9,9′-di- n -octylfluorenyl-2,7-diyl) (F8) was revealed by blending them in ternary hybrid with optimal ratio (F8/2 wt.% MEH-PPV/2 wt.% OC1C10–PPV–DMP). All individual and optimal ternary solutions were prepared via the solution-blending method followed by depositing them onto glass and ITO substrates using spin-coating technique. The semi-crystalline phase of the ternary hybrid and the strong mixing between the conjugated polymers were evidenced by observing the X-ray diffraction patterns that related to F8 into the hybrid diffractogram. The optical and optoelectronic properties of all prepared thin films were investigated in terms of absorption and emission spectra, Commission International d′Eclairage (CIE) coordinates, and current–voltage (I-V) characterizations. Emission peaks at the entire range of visible spectrum can be revealed from the ternary hybrid of the three individual conjugated polymers, producing white emission as evidenced from the emission spectrum and CIE coordinates of the hybrid. Among all fabricated organic light-emitting diodes (OLEDs) devices, the ternary hybrid-based-OLED revealed the best performance in terms of current and turn-on voltage. 相似文献
4.
The magnetic filtration theory was evaluated to intensify the filtration of industrial fluids by magnetic filters. Effects of filtration velocity and external magnetic field intensity on filter performance were investigated and the dependence of the logarithmic efficiency coefficient on filtration velocity was questioned. It was concluded that change in the magnetic susceptibility of the dispersion particles, caused by external magnetic field, and change in the flow rate properties of the liquid alongside the filter pores are the most essential factors to be considered in the design, development, and modeling of magnetic filtration systems in various industrial areas. 相似文献
5.
Solubility of drugs in aqueous media is a real issue for scientists and a lot of work is going on to resolve the issue. The same is the case for ibuprofen, which is a derivative of propionic acid, belongs to the NSAIDs family and has low solubility in pure water. Therefore, its solubility has been investigated in dimethyl dodecyl ammonium-propane sulfonate, DDAPS, micellar solution, DDAPS/butanol mixtures and in various (hexane, decane and tetradecane) oil-in-water microemulsions to find out a suitable vehicle. The aggregation number, size and flow ability of micelles and microemulsions were estimated using refractive index, viscosity and light scattering measurements. It has been observed that these microemulsions have a higher ability to solubilize ibuprofen than DDAPS/butanol mixtures or DDAPS micelles. 相似文献
6.
Anatoli F. Ivanov Musa A. Mammadov Sergei I. Trofimchuk 《Journal of Global Optimization》2013,56(2):251-263
A class of scalar nonlinear difference equations with delay is considered. Sufficient conditions for the global asymptotic stability of a unique equilibrium are given. Applications in economics and other fields lead to consideration of associated optimal control problems. An optimal control problem of maximizing a consumption functional is stated. The existence of optimal solutions is established and their stability (the turnpike property) is proved. 相似文献
7.
Musa A. Said K. C. Kumara Swamy 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Hydrolysis of several cyclic aminophosphites are discussed and compared with that of cyclic chloro/ phenoxy phosphites. An X-ray structure of a hydrolysis product, (C6H11NH3)+O?P(O)(H)(2,2′-OC6H4-C6H4OH) has been determined. 相似文献
8.
A new expression is proposed to determine the unperturbed dimensions of coil-like polymers viscometrically by use of the Flory and Kratky expression. The unperturbed dimensions so estimated are compared with the results obtained by using different expressions available in the literature. The results are comparable even for stiff chain polymers. The data obtained under theta conditions also fit this expression very well. The effect of molecular weight, its distribution, and that of the solvent has also been studied. It is concluded that the unperturbed dimensions are independent of molecular weight and solvent but depend on the heterogeneity of the system. 相似文献
9.
Hemn A. H. Barzani Hoshyar Saadi Ali Cihat Şahin Musa Kıran Yavuz Yardım 《Electroanalysis》2022,34(8):1280-1288
An effective electrochemical sensor was constructed using an unmodified boron-doped diamond electrode for determination of genistein by square-wave voltammetry. Cyclic voltammetric investigations of genistein with HClO4 solution indicated that irreversible behavior, adsorption-controlled and well-defined two oxidation peaks at about +0.92 (PA1) & +1.27 V (PA2). pH, as well as supporting electrolytes, are important in genistein oxidations. Quantification analyses of genistein were conducted using its two oxidation peaks. Using optimized experiments as well as instrumental conditions, the current response with genistein was proportionately linear in the concentrations range of 0.1 to 50.0 μg mL−1 (3.7×10−7−1.9×10−4 mol L−1), by the detection limit of 0.023 μg mL−1 (8.5×10−8 mol L−1) for PA1 and 0.028 μg mL−1 (1.1×10−7 mol L−1) for PA2 in 0.1 mol L−1 HClO4 solution (in the open circuit condition at 30 s accumulation time). Ultimately, the developed method was effectively applied to detect genistein in model human urine samples by using its second oxidation peak (PA2). 相似文献
10.
Prof. Dr. Musa M. Musa 《ChemistryOpen》2022,11(4):e202100251
Biocatalytic production of both enantiomers of optically active alcohols with high enantiopurities is of great interest in industry. Alcohol dehydrogenases (ADHs) represent an important class of enzymes that could be used as catalysts to produce optically active alcohols from their corresponding prochiral ketones. This review covers examples of the synthesis of optically active alcohols using ADHs that exhibit anti-Prelog stereopreference. Both wild-type and engineered ADHs that exhibit anti-Prelog stereopreference are highlighted. 相似文献