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排序方式: 共有115条查询结果,搜索用时 15 毫秒
21.
A front-tracking/ghost-fluid method is introduced for simulations of fluid interfaces in compressible flows. The new method captures fluid interfaces using explicit front-tracking and defines interface conditions with the ghost-fluid method. Several examples of multiphase flow simulations, including a shock–bubble interaction, the Richtmyer–Meshkov instability, the Rayleigh–Taylor instability, the collapse of an air bubble in water and the breakup of a water drop in air, using the Euler or the Navier–Stokes equations, are performed in order to demonstrate the accuracy and capability of the new method. The computational results are compared with experiments and earlier computational studies. The results show that the new method can simulate interface dynamics accurately, including the effect of surface tension. Results for compressible gas–water systems show that the new method can be used for simulations of fluid interface with large density differences. 相似文献
22.
We obtain cosmological solutions which admit emergent universe (EU) scenario in the framework of Einstein Gauss–Bonnet (GB)
gravity coupled with a dilaton field in 4-dimensions. The coupling parameter of the GB terms and the dilaton in the theory
are determined for obtaining an EU scenario. The corresponding dilaton potential which admits such scenario is determined.
It is found that the GB terms coupled with a dilaton field plays an important role in describing the dynamics of the evolution
of the early as well as the late universe. We note an interesting case where the GB term dominates initially in the asymptotic
past regime, subsequently it decreases and thereafter its contribution in determining the dynamics of the evolution dominates
once again. We note that the Einstein’s static universe solution permitted here is unstable which the asymptotic EU might
follow. We also compare our EU model with supernova data. 相似文献
23.
Complex formation between cationically modified gold nanoparticles and DNA: an atomic force microscopic study 总被引:1,自引:0,他引:1
Ganguli M Babu JV Maiti S 《Langmuir : the ACS journal of surfaces and colloids》2004,20(13):5165-5170
Atomic force microscopy has been used for direct visualization of the wrapping of DNA around 30-nm-sized functionalized gold nanoparticles for the first time. The morphology of the complexes seems to be dictated by the relative concentration of the nanoparticles and DNA. A higher concentration of the former leads to the formation of a network of nanoparticles assembled on DNA. This assembly pattern seems to be significantly different from the manner in which cationically modified gold nanoparticles of smaller size (< 5 nm) arrange linearly on DNA, as shown in the literature. A DNA-gold nanoparticle can be developed as a model system for in vitro studies on the mechanism of DNA condensation and also for developing novel methods of nanoparticle self-assembly on the DNA template. 相似文献
24.
Souvik Guha Ibrahim Yussif El-Deeb Shalini Yadav Ranajit Das Dr. Kshatresh Dutta Dubey Mousumi Baruah Dr. Ludovic Gremaud Prof. Dr. Subhabrata Sen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202202405
Herein we have reported the discovery of a pentacyclic building block comprised of fused indole-quinoline and piperidinone from the natural product perophoramidine as a formidable anticancer agent. The compounds were synthesized in six steps where the key steps involved a blue LED mediated intramolecular cyclopropanation of the indole intermediates and concomitant reduction of the associated aryl nitro moiety to nitroso in the molecule. Cytotoxicity screening of the compounds against an array of cancer cells that is, MCF7, HCT116 and A549 demonstrated 0.6 to 9 μM IC50s by few of the compounds. γH2AX immunofluorescence assay of the two most potent molecules from the phenotypic screening with anti-γ-H2AX Alexa Fluor 488 antibody revealed extensive DNA damage of the A549 cells which indicated probable PARP inhibition (similar to Perophoramidine). Through molecular docking and molecular dynamic (MD) simulation studies the binding efficiency of our compounds with poly(ADP-ribose)polymerase 1 (PARP 1) enzyme was determined. Chemiluminescent PARP Assay with Histone-coated strips indicated that the most active compounds from the phenotypic screening induced PARP-1 inhibition with IC50s of 1.3→1.5 μM. 相似文献
25.
The mean excess plot is a tool widely used in the study of risk, insurance and extreme values. One use is in validating a generalized Pareto model for the excess distribution. This paper investigates some theoretical and practical aspects of the use of the mean excess plot. 相似文献
26.
Souvik Biswas 《Tetrahedron letters》2010,51(13):1727-4666
Nucleophilic cationization reagents fitted with aminooxy groups are described. Practical syntheses of mono- and bis-aminooxy tetraalkylammonium iodides including N-hydroxyethyl-functionalized analogs are reported. An oximation example using one of the reagents is presented to illustrate their use in synthesis of cationic materials. 相似文献
27.
The large deviations of an infinite moving average process with exponentially light tails are very similar to those of an i.i.d. sequence as long as the coefficients decay fast enough. If they do not, the large deviations change dramatically. We study this phenomenon in the context of functional large, moderate and huge deviation principles. 相似文献
28.
Randip K. Das Souvik Bhattacharyya M. DuttaGupta B. B. Ghosh 《Experimental Thermal and Fluid Science》1999,19(4):243-222
The fuel economy potential of lean-burn gasoline engines can be utilized without any adverse effect on the environment, only if a suitable catalytic system for converting NOx in an oxidizing atmosphere is available. Selective catalytic reduction of NOx over metal-exchanged zeolite can be one of the solutions for reducing NOx in automobile exhaust containing excess oxygen. Iron-exchanged X-zeolite catalyst (Fe–X) has been developed and tested in the exhaust of an actual SI engine over a wide range of air–fuel ratio, space velocity (SV) and catalyst temperature. Maximum conversion efficiencies of 55.8% and 57.4% were recorded for NOx and CO, respectively. The catalyst also maintains its high performance through a wide range of temperatures. A mathematical model has been developed as well for predicting the performance of the catalytic converter containing Fe–X catalyst and the numerical solutions are presented. The predicted results agree well with the experimental results and are within the experimental uncertainty limits. The absolute average deviations are found to be within 6% and 5% of the predicted conversion efficiencies for NOx and CO, respectively. 相似文献
29.
Maiti S Chatterji PR Nisha CK Manorama SV Aswal VK Goyal PS 《Journal of colloid and interface science》2001,240(2):630-635
Aggregation behavior in aqueous solution of a series of poly (ethylene glycol) (PEG)-based macromonomers with methacryloyl group as the only hydrophobic segment has been investigated using surface tension, steady-state and time-resolved fluorescence spectroscopy using pyrene as a probe, and small-angle neutron scattering techniques. The general formula of these macromonomers is CH2=C(CH3)–CO–O–Em–CH3, where E is the ethylene glycol unit and m=8 (ME8), 18 (ME18), 49 (ME49), and 120 (ME120). The results indicate that a macromonomer with 8 ethylene glycol units forms as an aggregate above a certain critical concentration, which can be defined as critical aggregation concentration. The observed high value of I1/I3 in pyrene emission spectra at the interface of these aggregates and the inability to scatter a neutron beam by these aggregates indicate that the hydrophobic cluster formed by this macromonomer is remarkably solvated. ME18 has a tendency to aggregate but others do not form any hydrophobic cluster. The homopolymerization behaviors of these macromonomers in an aqueous medium at 70°C are consistent with these possibi- lities. 相似文献
30.
Nicholas A. A. Rossi Vaibhav Jadhav Benjamin F. L. Lai Souvik Maiti Jayachandran N. Kizhakkedathu 《Journal of polymer science. Part A, Polymer chemistry》2008,46(12):4021-4029
The controlled synthesis and characterization of a range of stimuli responsive cationic terpolymers containing varying amounts of N‐isopropylacrylamide (NIPAM), 3‐(methylacryloylamino)propyl trimethylammonium chloride (MAPTAC), and poly(ethylene glycol)monomethyl methacrylate (PEGMA) is presented. The terpolymers were synthesized using reversible addition‐fragmentation chain transfer (RAFT) polymerization. Compositions of the terpolymers determined using 1H NMR were in close agreement to the theoretical values determined from the monomer feed ratios. GPC‐MALLS was used to analyze the molecular weight characteristics of the polymers, which were found to have low polydispersities (Mw/Mn 1.1–1.4). The phase transitions were studied as a function of PEGMA and NIPAM content using temperature controlled 1H NMR and turbidity measurements (UV‐Vis). The relationship between thermal stability and the comonomer ratio of the polymers was measured using thermogravimetric analysis (TGA). Protein interaction studies were performed to determine the suitability of the polymers for biological applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4021–4029, 2008 相似文献