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141.
Md. Rafiquzzaman Md. Maksudul Islam Md. Habibur Rahman Md. Saniat Talukdar Md. Nahid Hasan 《先进技术聚合物》2016,27(10):1308-1316
The natural fibers such as jute, coir, hemp, sisal etc. are randomly used as reinforcements for composite materials because of its various advantages such as low cost, low densities, low energy consumption over conventional fibers. In addition, they are renewable as well as biodegradable, and indeed wide varieties of fibers are locally available. In this study, glass–jute fiber reinforced polymer composite is fabricated, and the mechanical properties such as tensile, flexural and impact behavior are investigated. The materials selected for the studies were jute fiber and glass fiber as the reinforcement and epoxy resin as the matrix. The hand lay‐out technique was used to fabricate these composites. Fractured surface were comprehensively examined in scanning electron microscope (SEM) to determine the microscopic fracture mode. A numerical procedure based on the finite element method was then applied to evaluate the overall behavior of this composite using the experimentally applied load. Results showed that by incorporating the optimum amount of jute fibers, the overall strength of glass fiber reinforced composite can be increased and cost saving of more than 30% can be achieved. It can thus be inferred that jute fiber can be a very potential candidate in making of composites, especially for partial replacement of high‐cost glass fibers for low load bearing applications. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
142.
Ali Reza Kazemizadeh Nahid Shajari Reza Shapouri Neda Adibpour Reza Teimuri-Mofrad 《Journal of the Iranian Chemical Society》2016,13(7):1349-1355
An isocyanide-based multicomponent reaction between cinnamic acid derivatives or 3-phenyl-2-propynoic acid, (N-isocyanimino)triphenylphosphorane, ferrocenecarbaldehyde, and dibenzylamine has been reported in excellent yields for the preparation of some new ferrocenyl-containing 1,3,4-oxadiazole derivatives. The anti-brucella activities of the products are investigated in in vitro and in vivo assays. 相似文献
143.
A rapid, simple, and sensitive differential kinetic method is presented for the determinations of acetaminophen (also known as paracetamol) and salicylamide. The method is based on their oxidation reaction by Fe3+ ion in the presence of 1, 10-phenanthroline as indicator. The reactions can be monitored spectrophotometrically by measuring the increase in the absorbance of the solution at 510 nm. Two times were selected one in which only paracetamol is oxidized by Fe3+ ion and the other in which both drugs are oxidized by Fe3+ ion. The data were evaluated by the proportional equations method. The method allowed the simultaneous determination of paracetamol and salicylamide at concentrations between 0.5-20 and 1-40 microg/mL with relative standard deviations of 3.47 and 2.58%, respectively. The method was applied to the simultaneous determination of paracetamol and salicylamide in human serum and pharmaceutical formulations. 相似文献
144.
Published results of vapour—liquid and vapour—solid equilibrium studies for neon—krypton and neon—oxygen mixtures have been analysed to give values for the interaction second virial coefficients. B12. Comparisons are made with other results for the NeKr system and with the predictions of some proposed intermolecular potentials. 相似文献
145.
Zakiyeh Gerivani Nahid Ghasemi Mohammad Abdollahi Ali A. Maleki Rad 《液相色谱法及相关技术杂志》2018,41(3):101-106
Introduction: Solvent bar microextraction technique is a sample preparation method prior to analysis for complicated matrices such as urine, blood, stem cell culture, and wastewater. This method, when coupled with adaptive-network-based fuzzy inference system, can detect and predict the concentration of trace elements and drugs at ultra-trace levels in complicated matrices.Material and method: Rizatriptan was used as a model drug for validation of this method. Therefore, six parameters (pH of donor and acceptor phase, stirring rate, time, temperature, and salt addition) affecting the preconcentration and determination of this drug were investigated. In this method, pH gradient was applied to transfer the drug into the solvent bar. MATLAB version 2010 was used for data analysis. Construction of an input-output mapping was done based on the results obtained from the experiments. For the simulation, the ANFIS architecture was employed to model nonlinear functions, identify nonlinear components in a control system, and predict a chaotic time series, all yielding remarkable results. Based on the best model chosen, the drug was preconcentrated and analyzed under the optimum condition.Results and discussion: The figures of merit were as follows: preconcentration factor: 127; limit of detection: 15?ng?mL?1; limit of quantification: 50?ng?mL?1; R2:0.999; RSD: 3.0%(interday) and 4.6% interaday. As a result, this method can be employed for preconcentration and microextraction of several elements, drugs, antibodies at trace levels in complicated matrices. After modeling, the optimum condition could be predicted without performing unnecessary and expensive experiments.Conclusion: Certain biomarkers can also be preconcentrated and detected using the proposed method. It offers high sample clean up, therefore it can be used for clean validation. Prediction of the course of treatment may be possible with the proposed method, therefore it is highly practical, easy and cost-effective. 相似文献
146.
In this work, the tautomeric transformations of a 1,5-dimethyl-6-thioxo-1,3,5-triazinane-2,4-dione molecule are explored at the M062X/6-311G(d,p) level of theory in gas and solution phases. These calculations show that the 1,5-dimethyl-6-thioxo-1,3,5-triazinane-2,4-dione isomer is more stable than its tautomer (4-hydroxy-1,5-dimethyl-6-thioxo-5,6-dihydro-1,3,5-triazin-2(1H)-one) in gas and solution phases. The frontier molecular orbitals and band gap energy calculations are performed at the M062X/6-311G(d,p) level in gas and various solvents. Solvent effects are analyzed using the self-consistent reaction field method based on the polarizable continuum model in chloroform, chlorobenzene, tetrahydrofurane, dichloromethane, and quinoline. The solvent effect on the N–H and C=O vibrations is explored. Also, natural bond orbital (NBO) analysis was used to understand the structure and bonding of the molecule. 相似文献
147.
Shamim Ahmad Khan Shahnawaz Ahmad Bhat Shahab A.A. Nami Abdul Kareem Nahid Nishat 《Comptes Rendus Chimie》2018,21(9):872-879
Coordination polymers were obtained by the reaction of metal acetates, M(CH3COO)2·xH2O {where M = Mn(II), Co(II), Ni(II) and Cu(II)} with AFP ligand (AFP = 5,5'-(piperazine-1,4-diylbis(methylene))bis(2-aminobenzoic acid). The AFP ligand was prepared by the one-pot, two-step reaction of formaldehyde, 2-aminobenzoic acid, and piperazine. Structural and spectroscopic properties have been studied by elemental, spectral (FT-IR, 1H NMR, 13C NMR, and UV–vis), and thermogravimetric analysis. UV–vis spectra and magnetic moment values indicate that Mn(II), Co(II), and Ni(II) polymer–metal complexes are octahedral, while Cu(II) and Zn(II) polymer–metal complexes are distorted octahedral and tetrahedral, respectively. The analytical data confirmed that the coordination polymers of Mn(II), Co(II), Ni(II), and Cu(II) are coordinated with two water molecules, which are further supported by infrared spectra and thermogravimetric analysis data. The prepared polymer–metal complexes showed good antibacterial activities against all tested microorganisms; however, the AFP ligand was also found to be effective, but relatively less than their polymer–metal complexes. Along with antibacterial activity, all the polymer–metal complexes exhibit significant antifungal activity against most of the tested fungal strains. The results of antimicrobial activity reveals that the AFP–Cu(II) showed the highest antibacterial and antifungal activity than other polymer–metal complexes. 相似文献
148.
Sartaj Tabassum Nahid Nishat Saiyid A. A. Zaidi Farukh Arjmand Khwaja S. Siddiqi 《Transition Metal Chemistry》1995,20(1):13-18
Summary The free Schiff base macrocycles 1,4,7,10-tetraazacyclo-dodeca-5,6,11,12-tetraaminoacetic acid-4,6,10,12-tetraene (L1), 1,4,7,10-tetraazacyclododeca-5,6,11,12-tetraamino-phenyl-4,6,10,12-tetraene (L2) and 1,4,7,10-tetraazacyclo-dodeca-5,6,11,12-tetraaminopyridyl-4,6,10,12-tetraene (L3) have been prepared by the reaction of oxamidediacetic acid, oxamidediphenyl and oxamidedipyridyl, respectively, with ethylenediamine. Their complexes with first row transition metal ions, of types [MLCl2] and [MLCl2]Cl, have also been prepared and characterized by physico-chemical and spectroscopic methods. The complexes of divalent metal ions are non-ionic while those of trivalent metal ions appear to be 11 electrolytes. An octahedral geometry is proposed for all the complexes. 相似文献
149.
Second-order rate constants are reported for the cleavage of the phenyltin bond of phenyltriethyltin by mercury(II) salts in ethanol. propan-1-ol, propan2-ol and butan-1-ol. It is shown that the reactivity order for the mercury(II) salts is HgI3? << HgI2 < HgCl2. Activation parameters are reported, and on the basis of the low values of activation enthalpies the presence of an intermediate π-complex is suggested for the reactions. 相似文献
150.
Simultaneous determination of uranium and thorium using arsenazo III as a chromogenic reagent at pH 1.70 by H‐point standard addition method (HPSAM) and partial least squares (PLS) calibration is described. Under optimum conditions, the simultaneous determinations of uranium and thorium by HPSAM were performed. The absorbencies at one pair of wavelengths, 649 and 669 nm, were monitored with the addition of standard solutions of uranium. The results of applying the HPSAM showed that uranium and thorium can be determined simultaneously with weight concentration ratios of uranium to thorium varying from 20:1 to 1:15 in the mixed sample. By multivariate calibration methods such as PLS, it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. In this study, the calibration model is based on absorption spectra in the 600–750 nm range for 25 different mixtures of uranium and thorium. Calibration matrices contained 0.10–21.00 and 0.25–18.5 μg mL?1 of uranium and thorium, respectively. The RMSEP for uranium and thorium were 0.7400 and 0.7276, respectively. Both proposed methods (HPSAM and PLS) were also successfully applied to the determination of uranium and thorium in several synthetic and real matrix samples. 相似文献