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41.
Ramakrishna G Jose DA Kumar DK Das A Palit DK Ghosh HN 《The journal of physical chemistry. B》2005,109(32):15445-15453
Dynamics of interfacial electron transfer (ET) in the ruthenium-polypyridyl complex [{bis(2,2'-bpy)-(4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol)} ruthenium(II) hexafluorophosphate] (Ru-cat)-sensitized TiO(2) nanoparticles has been investigated using femtosecond transient absorption spectroscopy detecting in the visible and near-infrared region. It has been observed that Ru-cat is coupled strongly with the TiO(2) nanoparticles through its pendant catechol moiety. Electron injection has been confirmed by direct detection of electrons in the conduction band, cation radical of the adsorbed dye, and a bleach of the dye in real time as monitored by transient absorption spectroscopy. A single-exponential and pulse width limited (<100 fs) electron injection has been observed, and the origin of it might have been from the nonthermalized excited states of the Ru-cat molecule. The result gave a strong indication that the electron injection competes with the thermalization of the photoexcited states due to large coupling elements for the forward ET reaction. Back-ET dynamics has been determined by monitoring the decay kinetics of the cation radical and injected electron and also from recovery kinetics of the bleach of the adsorbed dye. It has been fit with a multiexponential function, where approximately 30% of the injected electrons are recombined with a time constant of <2 ps, again indicating large coupling elements for the charge recombination reaction. However, our results have shown relatively long-lived charge separation in the Ru-cat/TiO(2) system as compared to other organic dye-sensitized TiO(2) nanoparticles with similar interactions. 相似文献
42.
Medha Rele Sudhir Kapoor Dipak K Palit Tulsi Mukherjee 《Research on Chemical Intermediates》2004,30(9):847-856
The effect of laser pulse irradiation on silver metal nanoparticles in ethylene glycol and glycerol is studied and compared with the parallel processes in aqueous solutions. The influence of 355 nm laser pulse irradiation at the surface plasmon frequency and on the size of the silver nanoparticles is examined by UV-Vis absorption spectroscopy and by transmission electron microscopy. It appears that viscosity of the medium plays a crucial role for the stabilization of the melted particles in the absence of the stabilizer. In ethylene glycol containing PVP, fragmentation of particles was observed. In neat glycerol, similar excitation led to morphological changes as the nanoparticles fused to produce particles of larger size. The changes in reduction of shape and size are considered to occur through melting and vaporization of the silver nanoparticles. 相似文献
43.
Parag Palit Farhana Tasnim Chowdhury Namrata Baruah Bonoshree Sarkar Sadia Noor Mou Mehnaz Kamal Towfida Jahan Siddiqua Zannatun Noor Tahmeed Ahmed 《Molecules (Basel, Switzerland)》2022,27(6)
Shigella species account for the second-leading cause of deaths due to diarrheal diseases among children of less than 5 years of age. The emergence of multi-drug-resistant Shigella isolates and the lack of availability of Shigella vaccines have led to the pertinence in the efforts made for the development of new therapeutic strategies against shigellosis. Consequently, designing small-interfering RNA (siRNA) candidates against such infectious agents represents a novel approach to propose new therapeutic candidates to curb the rampant rise of anti-microbial resistance in such pathogens. In this study, we analyzed 264 conserved sequences from 15 different conserved virulence genes of Shigella sp., through extensive rational validation using a plethora of first-generation and second-generation computational algorithms for siRNA designing. Fifty-eight siRNA candidates were obtained by using the first-generation algorithms, out of which only 38 siRNA candidates complied with the second-generation rules of siRNA designing. Further computational validation showed that 16 siRNA candidates were found to have a substantial functional efficiency, out of which 11 siRNA candidates were found to be non-immunogenic. Finally, three siRNA candidates exhibited a sterically feasible three-dimensional structure as exhibited by parameters of nucleic acid geometry such as: the probability of wrong sugar puckers, bad backbone confirmations, bad bonds, and bad angles being within the accepted threshold for stable tertiary structure. Although the findings of our study require further wet-lab validation and optimization for therapeutic use in the treatment of shigellosis, the computationally validated siRNA candidates are expected to suppress the expression of the virulence genes, namely: IpgD (siRNA 9) and OspB (siRNA 15 and siRNA 17) and thus act as a prospective tool in the RNA interference (RNAi) pathway. However, the findings of our study require further wet-lab validation and optimization for regular therapeutic use for treatment of shigellosis. 相似文献
44.
45.
Prabir K. Dutt Santi R. Palit 《Journal of polymer science. Part A, Polymer chemistry》1970,8(1):15-24
Dihydrocivetone, a macrocyclic ketone, has been found to be a weak initiator of vinyl polymerization. Anhydrous zinc chloride strongly promotes this to form a novel initiating system. Monomers tried successfully are methyl methacrylate, acrylonitrile and α-methylstyrene. The characteristic feature of polymerization of α-methylstyrene differs greatly from those of other monomers and those have been discussed and compared. 相似文献
46.
Ferrous-bromate redox is a very efficient initiator for the aqueous polymerization of a number of vinyl monomers. With methylmethacrylate, polymerization takes place in dark and at temperatures starting from 0 °C onwards. Bromate, ferrous and monomer exponents are respectively 0.51, 0.43 and 1.32 and the overall activation energy is 7.47 Kcal/mole. Neutral salts depress the polymerization rate, while an emulsifier increases it. pH of the medium has not much influence on the polymerization rate upto the value of 2.32. However, at pH 1.39, rate is somewhat depressed. Endgroups incorporated are hydroxyl and bromine totalling to an average of one per chain. Based upon these findings suitable mechanisms of initiation and termination have been proposed. 相似文献
47.
48.
Lifetimes of high spin states up to {
}=22+ in the yrast positive parity bands have been measured to investigate the shape evolution with increasing spin in 72, 74Se. The Q
t values derived from these measurements indicate that prolate shape stabilizes for 72Se, while a triaxial shape develops for 74Se at higher spins. Comparison of the observed trend in Q
t with spin for 72, 74Se with that of the corresponding kryptones isotones emphasizes the stability provided by N=38 prolate shell gap even at high rotational frequency. 相似文献
49.
An asymmetric aldol reaction between aldehyde 31 and imide 32, followed at a later stage by ring-closing metathesis (38 --> 40), are key reactions used to make optically pure allylic alcohol 40. Radical cyclization of the derived Stork bromo acetals gives lactol ethers 43, which were degraded to generate a quaternary center carrying a methoxycarboxyl group (44 --> 47). Compound 47 was converted into (+)-puraquinonic acid; and comparison with a natural sample established that the configuration of the natural compound is 2R (1). 相似文献