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991.
Sanjay Kumar Singh Santosh Kumar Dubey Rampal Pandey Lallan Mishra Ru-Qiang Zou Qiang Xu Daya Shankar Pandey 《Polyhedron》2008
The new cationic mononuclear complexes [(η6-arene)Ru(Ph-BIAN)Cl]BF4 [η6-arene = benzene (1), p-cymene (2)], [(η5-C5H5)Ru(Ph-BIAN)PPh3]BF4 (3) and [(η5-C5Me5)M(Ph-BIAN)Cl]BF4 [M = Rh (4), Ir (5)] incorporating 1,2-bis(phenylimino)acenaphthene (Ph-BIAN) are reported. The complexes have been fully characterized by analytical and spectral (IR, NMR, FAB-MS, electronic and emission) studies. The molecular structure of the representative iridium complex [(η5-C5Me5)Ir(Ph-BIAN)Cl]BF4 has been determined crystallographically. Complexes 1–5 effectively catalyze the reduction of terephthaldehyde in the presence of HCOOH/CH3COONa in water under aerobic conditions and, among these complexes the rhodium complex [(η5-C5Me5)Rh(Ph-BIAN)Cl]BF4 (4) displays the most effective catalytic activity. 相似文献
992.
New organic dyes containing a diarylaminofluorene unit as an electron donor and cyanoacrylic acid as acceptor and anchoring group in a donor-π-donor-π-acceptor architecture have been synthesized and characterized as sensitizers for nanocrystalline TiO(2)-based dye-sensitized solar cells. They have shown three major electronic absorptions originating from the π-π* and charge-transfer transitions covering the broad visible range (250-550 nm) in solution. The charge-transfer transition of the dyes exhibited negative solvatochromism, suggesting a polarized ground state. They have also displayed acidochromism in solution owing to the presence of a protonation-deprotonation equilibrium. On comparison with the triphenylamine and carbazole-based parent dyes (E)-2-cyano-3-(4-(diphenylamino)phenyl)acrylic acid and (E)-2-cyano-3-(9-ethyl-9H-carbazol-3-yl)acrylic acid they exhibited longer wavelength absorptions and facile oxidation, indicating the stronger electron-donating ability of the auxiliary chromophores. In addition, they exhibited nearly two times larger light-to-electron conversion efficiency under simulated AM 1.5 G irradiation (100 mW cm(-2)) with an aperture mask when compared to the parent dyes. Among the new dyes, the one containing the naphthylphenylamine segment showed better device characteristics attributable to the higher HOMO energy level which probably facilitates the regeneration of the dye and effective suppression of the back reaction of the injected electrons with the I(3)(-) in the electrolyte. The optical properties of the dyes were modeled using TDDFT simulations employing different theoretical models (B3LYP, CAM-B3LYP, and MPW1K), and the best correlations with the observed parameters have been found for CAM-B3LYP and MPW1K calculations. The electron lifetimes extracted from the electrochemical impedance measurements of the dye-sensitized solar cells were used to interpret the solar cell efficiency alternations. 相似文献
993.
Gagan Chhabra Chandra K. Singh Deeba Amiri Neha Akula Nihal Ahmad 《Molecules (Basel, Switzerland)》2021,26(5)
Immunomodulation of the tumor microenvironment is emerging as an important area of research for the treatment of cancer patients. Several synthetic and natural agents are being investigated for their ability to enhance the immunogenic responses of immune cells present in the tumor microenvironment to impede tumor cell growth and dissemination. Among them, resveratrol, a stilbenoid found in red grapes and many other natural sources, has been studied extensively. Importantly, resveratrol has been shown to possess activity against various human diseases, including cancer. Mechanistically, resveratrol has been shown to regulate an array of signaling pathways and processes involving oxidative stress, inflammation, apoptosis, and several anticancer effects. Furthermore, recent research suggests that resveratrol can regulate various cellular signaling events including immune cell regulation, cytokines/chemokines secretion, and the expression of several other immune-related genes. In this review, we have summarized recent findings on resveratrol’s effects on immune regulatory cells and associated signaling in various cancer types. Numerous immunomodulatory effects of resveratrol suggest it may be useful in combination with other cancer therapies including immunotherapy for effective cancer management. 相似文献
994.
Doshi DA Shah PB Singh S Branson ED Malanoski AP Watkins EB Majewski J van Swol F Brinker CJ 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):7805-7811
Neutron reflectivity (NR) is used to probe the solid, liquid, vapor interface of a porous superhydrophobic (SH) surface submerged in water. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160 degrees (superhydrophobic) to <10 degrees (hydrophilic). NR shows that the superhydrophobic nature of the surface prevents infiltration of water into the porous film. Atomic force microscopy and density functional theory simulations are used in combination to interpret the NR results and help establish the location, width, and nature of the SH film-water interface. 相似文献
995.
Support vector machines in water quality management 总被引:1,自引:0,他引:1
Support vector classification (SVC) and regression (SVR) models were constructed and applied to the surface water quality data to optimize the monitoring program. The data set comprised of 1500 water samples representing 10 different sites monitored for 15 years. The objectives of the study were to classify the sampling sites (spatial) and months (temporal) to group the similar ones in terms of water quality with a view to reduce their number; and to develop a suitable SVR model for predicting the biochemical oxygen demand (BOD) of water using a set of variables. The spatial and temporal SVC models rendered grouping of 10 monitoring sites and 12 sampling months into the clusters of 3 each with misclassification rates of 12.39% and 17.61% in training, 17.70% and 26.38% in validation, and 14.86% and 31.41% in test sets, respectively. The SVR model predicted water BOD values in training, validation, and test sets with reasonably high correlation (0.952, 0.909, and 0.907) with the measured values, and low root mean squared errors of 1.53, 1.44, and 1.32, respectively. The values of the performance criteria parameters suggested for the adequacy of the constructed models and their good predictive capabilities. The SVC model achieved a data reduction of 92.5% for redesigning the future monitoring program and the SVR model provided a tool for the prediction of the water BOD using set of a few measurable variables. The performance of the nonlinear models (SVM, KDA, KPLS) was comparable and these performed relatively better than the corresponding linear methods (DA, PLS) of classification and regression modeling. 相似文献
996.
Bimal P. Singh Jayadev Jena Laxmidhar Besra Sarama Bhattacharjee 《Journal of nanoparticle research》2007,9(5):797-806
The dispersion characteristics of nanosize silicon carbide (SiC) suspension were investigated in terms of surface charge,
particle size, rheological measurement and adsorption study. Ammonium polycarboxylate has been used as dispersant to stabilize
the suspension. It was found that the isoelectric point (iep) of SiC powder was pHiep (4.9). The surface charge of powder changed significantly in presence of the ammonium polycarboxylate dispersant and iep
shifted significantly towards lower acidic pH (3.6). The shift in iep has been quantified in terms of ΔG
0
SP, the specific free energy of adsorption between the surface sites and the adsorbing polyelectrolyte (APC). The values of
ΔG
0
SP (−10.85 RT unit) estimated by the electro kinetic data compare well with those obtained from adsorption isotherms (−9.521 RT unit). The experimentally determined optimum concentration of dispersant required for maximizing the dispersion was found
to be 2.4 mg/g of SiC (corresponding to an adsorbed amount of 1.10 mg/g), at pH 7.5. This is much below the full monolayer
coverage (corresponding to adsorbed amount of 1.75 mg/g) of the particles surface by the dispersant. The surface charge quantity,
rheological, pH, electro kinetic and adsorption isotherm results were used to explain and correlate the stability of the nanosize
silicon carbide in aqueous media. At pH 7.5, where both SiC surface and APC are negatively charged, the adsorption of APC
was low because of limited availability of favourable adsorption sites. In addition, the brush-like configuration of the adsorbed
polymer prevented close approach of any additional dispersant; hence stabilization of the slurry happens at a comparatively
lower concentration than the monolayer coverage. 相似文献
997.
Structural Chemistry - A thorough investigation on whether a stepwise or a concerted pathway is involved in the synthesis of substituted N-benzoyl urea derivatives by reaction of substituted... 相似文献
998.
We carried out an efficient and facile synthesis of Zn(II) complexes with heterocyclic ligands based on 2-substituted benzothiazole moieties, 2-(2′-hydroxynaphthyl)benzothiazole, 2-(2′-hydroxyphenyl)benzothiazole, and 2-(2′-merceptophenyl)benzothiazole, and amino acids, glycine and alanine, are reported and also examined for antifungal and antibacterial activities. Ligands and complexes were characterized by FTIR, 1H NMR, and elemental analysis. 相似文献
999.
Barange DK Nishad TC Swamy NK Bandameedi V Kumar D Sreekanth BR Vyas K Pal M 《The Journal of organic chemistry》2007,72(22):8547-8550
Herein, we report transition metal-catalyzed intramolecular cyclization of o-(1-alkynyl)benzenesulfonamides to afford 3-substituted benzothiazines regioselectively via a C-N bond forming reaction and Cu-catalyzed sequential C-N and C-C bond formation leading to the corresponding 3,4-disubstituted derivatives. 相似文献
1000.