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Munawar Ali Munawar Muhammad Azad Hamid Latif Siddiqui Faiz‐Ul‐Hassan Nasim 《中国化学会会志》2008,55(2):394-400
The quinolinylpyrimidine derivatives were prepared by the condensation of quinolinyl chalcones with urea (or thiourea) under basic conditions by using both conventional and microwave heating. Their IR, 1H NMR, 13C NMR, mass spectra and CHN analyses confirmed the prepared compounds. The newly prepared quinolinylpyrimidine derivatives were screened for antimicrobial activities against the bacterial strains viz. S. aureus, Shigella, Salmonela, P. aeroginosa, B. Subtilus and E. coli and found considerably active against S. aureus, P. aeroginosa and E. coli. 相似文献
54.
Copper(II) complex of ethambutol (I) was prepared and used in the fabrication of Cu(2+) selective ISE membrane. The membrane having Cu(II)-ethambutol complex (I) as electroactive material, along with sodium tetraphenylborate (NaTPB) as anion discriminator, dioctylphthalate (DOP) as plasticizer in poly(vinyl chloride) (PVC) matrix in the percentage ratio 6:2:190:200 (I:NaTPB:DOP:PVC) (w/w) gave a linear response in the concentration range 7.94x10(-6) to 1.0x10(-1) M of Cu(2+) with a slope of 29.9+/-0.2 mV per decade of activity and a fast response time of 11+/-2 s. The sensor works well in the pH range 2.1-6.3 and could be satisfactorily used in presence of 40% (v/v) methanol, ethanol and acetone and is selective for copper over a large number of cations with slight interference from Na(+) and Co(2+) if present at a level 1.5x10(-5) and 6.5x10(-5) M, respectively. It works well over a period of 6 months and can also be used as indicator electrode for the end point determination in the potentiometric titration of Cu(2+) against EDTA as well as in the determination of Cu(2+) in real samples. 相似文献
55.
The iron(III) and cobalt(III) complexes of 2,3,7,8,12,13,17,18-octakis(benzylthio)-5,10,15,20-tetraazaporphyrin, (OBTAP) were synthesized and incorporated into PVC matrix as ionophores to fabricate anion selective membrane electrodes that exhibit selective potentiometric response to azide and nitrite ions, respectively. The membrane of [Fe(OBTAP)]+ (III) with a composition of 6:190:200 (III:DBP:PVC) (w/w), and of [Co(OBTAP)]+ (IV) with a composition of 10:148:200 (IV:DOP:PVC) (w/w), i.e. 1a and 2b, respectively (where DBP:dibutylphthalate and DOP=dioctylphthalate) gave the best performance. The membrane 1a showed a slope of 29.2±0.2 mV per decade of activity for N3− in the working concentration range of 8.9×10−6 to 1.0×10−1 M. The membrane 2b showed a slope of 30.0±0.2 mV per decade of activity for NO2− in the working concentration range of 1.1×10−5 to 1.0×10−1 M. The membranes worked satisfactorily in the pH range of 4.3-10.5 (1a) and 2.8-6.4 (2b) and had fast response time of 12±2 and 13±2 s, respectively. Electrodes exhibited a high degree of selectivity for N3− and NO2−, respectively, over several other monovalent and bivalent anions. Only SCN− and S2− (at >1.0×10−4 M) cause moderate interference for electrode 1a and Cl− and S2− (at >1.0×10−5 M) for electrode 2b. They gave reproducible results with the relative standard deviation in the observed values of potentials (σ) of 1.96 and 1.80 mV for electrodes 1a and 2b, respectively, from the least-squares fit line. The 90% confidence limit lies within ±0.2 mV per decade of activity. Reproducible results were obtained over a period of 5 months. Their performance in non-aqueous solvent mixtures having up to 50% (v/v) methanol, ethanol and acetone were evaluated and were found satisfactory. The proposed sensors are superior in terms of detection limit and response time in comparison to the reported ones. 相似文献
56.
Binding constants between the glycopeptides teicoplanin (Teic) and ristocetin (Rist) and their derivatives to D-Ala-D-Ala terminus peptides were determined by on-column receptor synthesis coupled to partial-filling affinity capillary electrophoresis (PFACE) or affinity capillary electrophoresis (ACE). In these techniques, the column is first partially filled with increasing concentrations of D-Ala-D-Ala terminus peptides. This is followed by plugs of buffer, antibiotic and two noninteracting standards, and acetic and/or succinic anhydride (and buffer in the case of ACE). The order of the reagent plugs containing the antibiotic and anhydride varies with the charge of the glycopeptide. Upon electrophoresis, the antibiotic reacts with the anhydride yielding a derivative of Teic or Rist. Continued electrophoresis results in the overlap of the derivatized antibiotic and the plug of D-Ala-D-Ala peptide. Analysis of the change in the relative migration time ratio (RMTR) of the new glycopeptide relative to the standards, as a function of the concentration of the D-Ala-D-Ala ligand yields a value for the binding constant K(b). The techniques described here can be used to assess how the derivatization of drugs alters their affinities for target molecules. 相似文献
57.
Mohammad Azad Igor Chikalov Shahid Hussain Mikhail Moshkov Beata Zielosko 《Entropy (Basel, Switzerland)》2021,23(12)
Conventional decision trees use queries each of which is based on one attribute. In this study, we also examine decision trees that handle additional queries based on hypotheses. This kind of query is similar to the equivalence queries considered in exact learning. Earlier, we designed dynamic programming algorithms for the computation of the minimum depth and the minimum number of internal nodes in decision trees that have hypotheses. Modification of these algorithms considered in the present paper permits us to build decision trees with hypotheses that are optimal relative to the depth or relative to the number of the internal nodes. We compare the length and coverage of decision rules extracted from optimal decision trees with hypotheses and decision rules extracted from optimal conventional decision trees to choose the ones that are preferable as a tool for the representation of information. To this end, we conduct computer experiments on various decision tables from the UCI Machine Learning Repository. In addition, we also consider decision tables for randomly generated Boolean functions. The collected results show that the decision rules derived from decision trees with hypotheses in many cases are better than the rules extracted from conventional decision trees. 相似文献
58.
Upadhyay Ranjit Kumar Chatterjee Sourin Saha Satvik Azad Rajeev K. 《Nonlinear dynamics》2020,101(3):1921-1932
Nonlinear Dynamics - Robust testing and tracing are key to fighting the menace of coronavirus disease 2019 (COVID-19). This outbreak has progressed with tremendous impact on human life, society and... 相似文献
59.
Li5ReN4, a Lithium Nitridorhenate(VII) with Anti Fluorite Superstructure At 673 K Li3N reacts with Re powder under N2 to pale yellow, microcrystalline Li5ReN4. The structure determination is based on X‐ray powder data: Spacegroup Pmmn (No. 59), Z = 2, a = 6.719(1) Å, b = 6.627(1) Å, c = 4.893(1) Å. The compound crystallizes in an anti‐type of a fluorite superstructure. In comparison to the aristo‐type – CaF2 – in Li5ReN4 tetrahedral interstices of a ccp nitrogen partial structure are unoccupied. The distribution of these vacancies is related with its orthorhombic distortion. Under aspects of crystal chemistry the tetragonally crystallizing compounds Li6MN4 with M = Mo, W result by partially filling up such vacancies. 相似文献
60.
Photoconductivity (PC) studies were carried out on GaS single crystals prepared from melt by directional solidification. We studied the effect of light intensity, applied voltage on both the PC and the lifetime of carriers. The V-I characteristics and the absorption spectra were checked for different sample thickness. The present investigation was extended to study the spectral distribution of the photocurrent for GaS. It was found that the photocurrent curves are practically independent of the bias voltage. The energy gap for GaS was found to be 2.5 eV. 相似文献