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991.
992.
Experimental Mechanics - Digital image correlation (DIC) is a powerful experimental technique for measuring full-field displacement and strain. The basic idea of the method is to compare images of... 相似文献
993.
994.
Vitor M. Correlo Ana R. Costa‐Pinto Paula Sol José A. Covas Mrinal Bhattacharya Nuno M. Neves Rui L. Reis 《Macromolecular bioscience》2010,10(12):1495-1504
We report the production of chitosan‐based fibers and chitosan fiber‐mesh structures by melt processing (solvent‐free) to be used as tissue‐engineering scaffolds. The melt‐based approach used to produce the scaffolds does not change their main characteristics, including the surface roughness and microporosity. The porosity, pore size, interconnectivity and mechanical performance of the scaffolds are all within the range required for various tissue‐engineering applications. Biological assessments are performed in direct‐contact assays. Cells are able to colonize the scaffold, including the inner porous structure. The cells show high indices of viability in all of the scaffold types.
995.
Srabanti Ghosh S. C. Bhattacharya Abhijit Saha 《Analytical and bioanalytical chemistry》2010,397(4):1573-1582
The gamma irradiation method has provided a route for synthesis of highly water-soluble, good-quality luminescent CdS/dendrimer
nanocomposites with amino- or carboxyl-terminated PAMAM dendrimer. An attempt has been made to probe ascorbic acid with the
as-synthesized CdS/dendrimer nanocomposites (DNC). Ascorbic acid (AA) is an important biological antioxidant and marker for
different diseases in clinical chemistry as well as in quality control in the food industry. Micromolar concentrations of
AA significantly quenched the photoluminescence (PL) of both amino (–NH2) and carboxylic (–COOH) functionalized semiconductor nanocomposites. The quenching followed a linear Stern–Volmer equation
and time-resolved photoluminescence spectroscopy confirmed its static nature. A strong size dependence of the quenching pattern
was observed. The binding constants, and the corresponding thermodynamic parameters ΔG
θ, ΔH
θ, ΔS
θ at different temperatures were calculated. CdS DNC showed selectivity towards ascorbic acid even in the presence of possible
interfering molecules, such as uric acid, tartaric acid and citric acid. Nanocomposites-based assay techniques could override
the complications involved in multitudes of assay procedures, providing a simple and fast new strategy for the quantification
of Ascorbic acid in the range of 16.6 to 100 μM (R = 0.998, n = 9). The proposed method was applied to the detection of ascorbic acid in Vitamin C tablets with satisfactory results. 相似文献
996.
Bhattacharya D Sathiyendiran M Wu JY Chang CH Huang SC Zeng YL Lin CY Thanasekaran P Lin BC Hsu CP Lee GH Peng SM Lu KL 《Inorganic chemistry》2010,49(22):10264-10272
Self-assembled, chair-shaped dirhenium(I) macrocyclic compounds featuring the two different bis-chelating quinone dianions (1, L = dhnq(2-); 2, L = dhaq(2-); H(2)dhnq = 6,11-dihydroxy-5,12-naphthacenedione; H(2)dhaq = 1,4-dihydroxy-9,10-anthraquinone) that interface with two fac-Re(CO)(3) cores and a ditopic semirigid N-donor 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)naphthalene (L' = p-NBimM) ligand coordinated to the remaining orthogonal site were prepared in high yields. Their structures were confirmed by single-crystal X-ray diffraction analysis. Electrochemical assessments, using cyclic voltammetry (CV) and UV-vis-NIR spectroelectrochemistry (SEC), revealed the existence of two well-separated, single-electron quinone ligand-centered, reversibly accessible 0, -1, and -2 redox states. Among the two singly reduced radical complexes, the symmetrically bridged quinone complex 1(?-), showed a strong absorption in the NIR regions, which was not observed for the neutral and doubly reduced states, analogous to that of the free dhnq(3?-) quinone. In contrast, when 2 was reduced to 2(?-), a broad signal at 866 nm was observed, very similar to the reduced dhaq(3?-) quinone. This difference in spectral behavior in the singly reduced states is likely due to the annealed benzene ring in 1 and dhnq(2-) because of its symmetrical π-electron system, which is perturbed to a lesser degree compared to asymmetric 2 and dhaq(2-). Reduction to 1(?-) produces a small but not negligible g factor anisotropy (Δg = 0.024) in the electron spin resonance (ESR) signal, indicative of a very small metal-centered spin (5%), but 2(?-) shows a g value in the expected range for organic radicals (no detectable Δg). Thus, the combined investigations reveal that the singly reduced metallacycles are best described as being highly stable, noncommunicating, localized, quinonoid-centered radical complexes, [(CO)(3)Re(I)(μ-L(3?-))(μ-L')Re(I)(CO)(3)](?-). 相似文献
997.
Chatterjee PB Audhya A Bhattacharya S Abtab SM Bhattacharya K Chaudhury M 《Journal of the American Chemical Society》2010,132(45):15842-15845
An unprecedented single crystal-to-single crystal transformation occurs when a binuclear oxovanadium(V) compound [V(V)(2)O(2)(L)(2)] 1 involving 2,6-bis(hydroxymethyl)-p-cresol (H(3)L) as a bridging ligand is exposed simultaneously to white light and aerial oxygen to generate an oligomeric compound [V(IV)(2)O(2)(L*)(2)] 2 (H(2)L* is 3-hydroxymethyl-5-methylsalicylaldehyde). Each vanadium(V) center in 1 is reduced to vanadium(IV) in 2 at the expense of a two-electron alcohol-to-aldehyde oxidation in the coordinated ligand. The additional electron being released is possibly consumed by molecular oxygen to generate hydrogen peroxide. 相似文献
998.
Gangopadhyay M Dewanjee S Bhattacharyya S Bhattacharya S 《Natural product communications》2010,5(12):1913-1916
The aim of the present study was to determine the effect of three strains of Agrobacterium rhizogenes (ATCC 15834, A4 and LBA 9402) and the nature of explants (leaf and stem) on hairy root induction, growth and plumbagin production in Plumbago indica. The first appearance of hairy roots, the transformation frequency, dry root biomass and plumbagin accumulation were found to be maximum in hairy roots induced in leaf explants infected with A. rhizogenes ATCC 15834 as compared with the other two bacterial strains. The hairy roots generated from stem explants infected with all three strains were not found to be productive in terms of the selected parameters. Finally, the insertion of the rolB gene of A. rhizogenes ATCC 15834 in hairy roots of P. indica derived from leaf explants was confirmed by PCR analysis. 相似文献
999.
The title compounds Ph3PbSPbPh3 (1) and Ph3SnSSnPh3 (2) were prepared in high yields by a reaction of Na2S, respectively, with Ph3Pb(SOCMe) and Ph3Sn(SOCMe). X-ray crystallographic and density functional studies were made to understand the structure and bonding in these molecules. Though the Pb–Pb distance in 1 is only marginally shorter than the sum of the corresponding van der Waals’ radii, a smaller Pb–S–Pb angle suggests for a Pb···Pb interaction. DFT calculations were performed to analyse the nature of M···M interaction in 1 and 2. Strong intramolecular π–π interactions subsist between the different phenyl rings of the molecules. 相似文献
1000.
Asish Pal Dr. Aasheesh Srivastava Dr. Santanu Bhattacharya Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):9169-9182
We incorporate various gold nanoparticles (AuNPs) capped with different ligands in two‐dimensional films and three‐dimensional aggregates derived from N‐stearoyl‐L ‐alanine and N‐lauroyl‐L ‐alanine, respectively. The assemblies of N‐stearoyl‐L ‐alanine afforded stable films at the air–water interface. More compact assemblies were formed upon incorporation of AuNPs in the air–water interface of N‐stearoyl‐L ‐alanine. We then examined the effects of incorporation of various AuNPs functionalized with different capping ligands in three‐dimensional assemblies of N‐lauroyl‐L ‐alanine, a compound that formed a gel in hydrocarbons. The profound influence of nanoparticle incorporation into physical gels was evident from evaluation of various microscopic and bulk properties. The interaction of AuNPs with the gelator assembly was found to depend critically on the capping ligands protecting the Au surface of the gold nanoparticles. Transmission electron microscopy (TEM) showed a long‐range directional assembly of certain AuNPs along the gel fibers. Scanning electron microscopy (SEM) images of the freeze‐dried gels and nanocomposites indicate that the morphological transformation in the composite microstructures depends significantly on the capping agent of the nanoparticles. Differential scanning calorimetry (DSC) showed that gel formation from sol occurred at a lower temperature upon incorporation of AuNPs having capping ligands that were able to align and noncovalently interact with the gel fibers. Rheological studies indicate that the gel–nanoparticle composites exhibit significantly greater viscoelasticity compared to the native gel alone when the capping ligands are able to interact through interdigitation into the gelator assembly. Thus, it was possible to define a clear relationship between the materials and the molecular‐level properties by means of manipulation of the information inscribed on the NP surface. 相似文献