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Ravi Kumar Reshmi R. Nair Saurabh Sudha Dhiman Jitender Sharma Om Prakash 《Journal of heterocyclic chemistry》2011,48(5):1211-1215
Synthesis of a series of new 4‐substituted‐3‐aryl‐1‐(2,6‐dimethylpyrimidin‐4‐yl)pyrazoles ( 2a , 2b , 2c , 2d , 2e , 2f , 2g , 3a , 3b , 3c , 3d , 3e , 3f , 3g , and 4a , 4b , 4c , 4d , 4e , 4f , 4g ) is described. All the synthesized compounds were evaluated in vitro for their antibacterial activity against two gram‐positive and two gram‐negative bacteria, namely, Bacillus subtilis (MTCC 8509), Bacillus stearothermophilus (MTCC 8508), Escherichia coli (MTCC 51), and Pseudomonas putida (MTCC 121), and their activity was compared with two commercial antibiotics, streptomycin and chloramphenicol. Two compounds, namely, 3‐(4‐anisyl)‐1‐(2,6‐dimethylpyrimidin‐4‐yl)pyrazole‐4‐carboxaldehyde ( 2b ) and 3‐(2‐thienyl)‐1‐(2,6‐dimethyl pyrimidin‐4‐yl)pyrazole‐4‐carboxaldehyde ( 2g ) were found to be equipotent to streptomycin and chloramphenicol against gram‐negative bacteria, E. coli having minimum inhibitory concentration (MIC) value = 4 μg/mL. Compounds 4b and 4d also displayed good activity against E. coli with MIC = 8 μg/mL. J. Heterocyclic Chem., (2011). 相似文献
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Harpreet?Kaur Charanjeet?SinghEmail author Randeep?Kaur Tanvi?Dhiman S.?Bindra Narang 《The European Physical Journal B - Condensed Matter and Complex Systems》2015,88(10):274
The microwave characteristics of Co2+ and Ti4+ ions substituted, BaCo x Ti x Fe(12?2x)O19 (x = 0.1, 0.3, 0.5, 0.7, 0.9) ferrite have been studied as a function of thickness, frequency and substitution. The results depict reflection loss of ? 31.94 dB at 10.47 GHz in x = 0.9. The highest static electrical current is observed at lower substitution. The model accompanying microwave absorption is used to evaluate microwave absorption characteristics. The electromagnetic and static electrical characteristics are improved with the substitution of Co2+ and Ti4+ ions. The compositions for possible electromagnetic applications are also explored. 相似文献
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Joginder Singh Dhiman 《Proceedings Mathematical Sciences》1995,105(4):461-469
The present paper extends the results of Banerjeeet al [2] for the hydromagnetic thermohaline convection problems of Veronis’ [9] and Stern’s [8] types to include the effect of
a uniform vertical rotation. 相似文献
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In recent experimental work, Chatterjee and Arakeri have demonstrated that an imposed acoustic field of sufficiently high strength and frequency can suppress or control cavitation. In this paper, we analytically study the equation governing the dynamics of a single bubble in a time-varying pressure field, for parameter ranges representative of those experimental conditions. The governing equation is strongly nonlinear and intractable in general; however, for the parameter ranges of interest, we are able to nondimensionalize and scale the governing equation into a form that, though still strongly nonlinear, is amenable to analysis using the method of multiple scales (MMS) based on an arbitrarily chosen “small” parameter ∊. Removal of secular terms, a key step in the MMS, raises an interesting issue which we discuss. Second order MMS gives the slow average evolution of the bubble radius. Numerical solutions of the original equation match the MMS approximation well on time scales of (1/∊). The MMS approximation also provides insight into the roles played by relevant physical parameters in the system. Our results provide theoretical support for the abovementioned experimental results. 相似文献
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Reactions of . OH/O .? radicals, H‐atoms as well as specific oxidants such as N and Cl radicals with 4‐hydroxybenzyl alcohol (4‐HBA) in aqueous solutions have been investigated at various pH values using the pulse radiolysis technique. At pH 6.8, . OH radicals were found to react with 4‐HBA (k = 6 × 109 dm3 mol?1 s?1) mainly by contributing to the phenyl moiety and to a minor extent by H‐abstraction from the ? CH2OH group. . OH radical adduct species of 4‐HBA, i.e., . OH‐(4‐HBA) formed in the addition reaction were found to undergo dehydration to give phenoxyl radicals of 4‐HBA. Decay rate of the adduct species was found to vary with pH. At pH 6.8, decay was very much dependent on phosphate buffer ion concentrations. Formation rate of phenoxyl radicals was found to increase with phosphate buffer ion concentration and reached a plateau value of 1.6 × 105 s?1 at a concentration of 0.04 mol dm?3 of each buffering ion. It was also seen that . OH‐(4‐HBA) adduct species react with HPO ions with a rate constant of 3.7 × 107 dm3 mol?1 s?1 and there was no such reaction with H2PO ions. However, the rate of reaction of . OH‐(4‐HBA) adduct species with HPO ions decreased on adding KH2PO4 to the solution containing a fixed concentration of Na2HPO4 which indicated an equilibrium in the H+ removal from . OH‐(4‐HBA) adduct species in the presence of phosphate ions. In the acidic region, the . OH‐(4‐HBA) adduct species were found to react with H+ ions with a rate constant of 2.5 × 107 dm3 mol?1 s?1. At pH 1, in the reaction of . OH radicals with 4‐HBA (k = 8.8 × 109 dm3 mol?1 s?1), the spectrum of the transient species formed was similar to that of phenoxyl radicals formed in the reaction of Cl radicals with 4‐HBA at pH 1 (k = 2.3 × 108 dm3 mol?1 s?1) showing that . OH radicals quantitatively bring about one electron oxidation of 4‐HBA. Reaction of . OH/O .? radicals with 4‐HBA by H‐abstraction mechanism at neutral and alkaline pH values gave reducing radicals and the proportion of the same was determined by following the extent of electron transfer to methyl viologen. H‐atom abstraction is the major pathway in the reaction of O .? radicals with 4‐HBA compared to the reaction of . OH radicals with 4‐HBA. At pH 1, transient species formed in the reactions of H‐atoms with 4‐HBA (k = 2.1 × 109 dm3 mol?1 s?1) were found to transfer electrons to methyl viologen quantitatively. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Sandeep Kaur Amrish Sharma Hitesh Sharma Shobhna Dhiman Isha Mudahar 《International journal of quantum chemistry》2019,119(23):e26019
Magnetic carbon nano-structures have potential applications in the field of spintronics as they exhibit valuable magnetic properties. Symmetrically sized small fullerene dimers are substitutional doped with nitrogen (electron rich) and boron (electron deficient) atoms to visualize the effect on their magnetic properties. Interaction energies suggests that the resultant dimer structures are energetically favorable and hence can be formed experimentally. There is significant change in the total magnetic moment of dimers of the order of 0.5 μB after the substitution of C atoms with N and B, which can also be seen in the change of density of states. The HOMO-LUMO gaps of spin up and spin down electronic states have finite energy difference which confirm their magnetic behaviour, whereas for non-magnetic doped dimers, the HOMO-LUMO gaps for spin up and down states are degenerate. The optical properties show that the dimers behave as optical semiconductors and are useful in optoelectronic devices. The induced magnetism in these dimers makes them fascinating nanocarbon magnetic materials. 相似文献
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Amarsinh R. Deshmukh Sambhaji T. Dhumal Laxman U. Nawale Vijay M. Khedkar Dhiman Sarkar 《合成通讯》2019,49(4):587-601
In a search of new potentially active antitubercular agents here we have synthesized 3-substituted phenyl-2-(4-(tetrazolo[1,5-a]quinolin-4-ylmethoxy)phenyl)thiazolidin-4-ones (8a–l) and evaluated their antibacterial, particularly antitubercular activity. These have been conveniently synthesized by performing one–pot cyclocondensation of 4-(tetrazolo[1,5-a]quinolin-4-ylmethoxy)benzaldehyde, anilines and mercaptoacetic acid in dicationic ionic liquid, (3-methyl-1-[3-(methyl-1H-imidazolium-1-yl)propyl]-1H-imidazolium dibromide [C3(MIM)2–2Br]) and obtained excellent yields of (8a–l). 4-Thiazolidinones (8a–l) were thoroughly characterized by their spectral analyses. These compounds have been screened for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Ra and Mycobacterium bovis (BCG). The compounds 8a, 8c, and 8e exhibited notable in vitro antitubercular activity compare to the reference, Rifampicin. Molecular docking study has also been performed to know the binding mode of these analogs in to the active site of DprE1 enzyme. The synthesized compounds were also evaluated for their in vitro antibacterial activity and amongst them compound 8k has shown moderate activity against both gram-negative and gram-positive bacterial strains. 相似文献