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781.
A. C. Patra S. Mohapatra S. K. Sahoo P. Lenka J. S. Dubey V. K. Thakur A. V. Kumar P. M. Ravi R. M. Tripathi 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):903-910
Activity concentrations of 238U, 232Th, 226Ra, 40K and 137Cs were measured in milk, egg, fruit and fish samples collected around a proposed site for setting up nuclear facilities, near Vishakhapatanam. The activity concentrations of the radionuclides ranged from 0.002 to 10.6, 0.002 to 2.8, 0.1 to 7.2, 3 to 110.8, 0.03 to 3 mBq g?1 for 238U, 232Th, 226Ra, 40K and 137Cs considering analysed food matrices. Natural uranium was measured in drinking water samples and the values were below 15 ppb. The average ingestion dose was 2.07 ± 2.01, 2.81 ± 4.38, 7.66 ± 8.24, 1.28 ± 0.84 and 0.04 ± 0.05 μSv year?1 for 238U, 232Th, 226Ra, 40K and 137Cs in milk, egg, fruit, fish and water. The ingestion dose received was the highest for milk, due to its high ingestion rate. It was observed that 226Ra is the largest contributor of measured radionuclides in this study for the different food matrices analysed due to its high dose conversion factor. The study was carried out as a part of baseline data generation for this region with which future changes in the radiological scenario can be compared. 相似文献
782.
S. Sugandhi V. M. Joshi S. K. Jha R. M. Tripathi 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(3):1345-1348
The observed 137Cs content in bottom sediment and benthic species of Mumbai off coast varied between 2–370 \( {\text{Bq kg}}_{{ ( {\text{dry)}}}}^{ - 1} \) and <0.08–0.4 \( {\text{Bq kg}}_{{ ( {\text{wet)}}}}^{ - 1} \) respectively. The annual estimated ingestion dose to ‘general public’ due to consumption of benthic species is 0.02 µSv y?1, which is infinitesimally smaller, in comparison to average annual human exposure of 3.01 mSv and also to the internationally accepted public dose limit of 1,000 µSv y?1. 相似文献
783.
The present study demonstrates improvement in sensitivity and specificity of hapten assay by using antigen heterology in conjunction with low molecular weight biotin label as compared to high molecular weight horseradish peroxidase (HRP) label. For generation of antiserum, cortisol-3-O-carboxylmethyl-oxime-bovine serum albumin (F-3-CMO-BSA) was used as immunogen whereas, for the preparation of primary label, corticosterone-3-carboxymethyl oxime (B-3-CMO) was coupled with biotinylcaproylhydrazide and HRP by employing N-hydroxysuccinimide mediated carbodiimide reaction. The data of the present study revealed that the antigen heterologous assay which employed high molecular weight HRP label showed 100% cross-reaction with corticosterone. On the contrary, when HRP was replaced with low molecular weight biotin label, less than 0.1% cross-reaction was observed with all analogous C18, C19, C21 and C27 steroids including corticosterone (0.2%). Moreover, the sensitivity of the later assay was 0.09 μg/dL, which is appreciable as compared to previously reported enzyme based assays. The recovery of the exogenously spiked serum pools lies in the range of 90.3-104.2%. The intra-assay and inter-assay coefficient of variation (CVs) ranged from 3.3% to 7.8% and 2.3% to 7.7%, respectively. The serum cortisol values obtained by this method correlated well with those obtained by radioimmunoassay; r = 0.9 (n = 50). The use of much stable biotin label in place of HRP has made the antigen heterologous enzyme linked immunosorbent assay (ELISA) of cortisol assay highly specific and sensitive. 相似文献
784.
Divya Tripathi 《Tetrahedron letters》2008,49(49):7012-7014
A versatile and efficient method for the enantioselective synthesis of 2,7-cis-disubstituted oxepane 1c, (+)-isolaurepan, using oxidative resolution of a secondary alcohol and highly diastereoselective Et3SiH/TMSOTf-promoted reductive cyclization of a hydroxy ketone is described. 相似文献
785.
A Ajay S Sharma MP Gupt V Bajpai Hamidullah B Kumar MP Kaushik R Konwar RS Ampapathi RP Tripathi 《Organic letters》2012,14(17):4306-4309
A new approach to synthesize a homologous series of 14-, 15-, and 16-membered drug-like, macrocyclic glycoconjugates involving TBAHS promoted azide-propenone intramolecular cycloaddition in designed C-glycopyranosyl butenones from a simple sugar d-glucose and d-mannose is reported. 相似文献
786.
Tripathi P Dupres V Beaussart A Lebeer S Claes IJ Vanderleyden J Dufrêne YF 《Langmuir : the ACS journal of surfaces and colloids》2012,28(4):2211-2216
In living cells, sophisticated functional interfaces are generated through the self-assembly of bioactive building blocks. Prominent examples of such biofunctional surfaces are bacterial nanostructures referred to as pili. Although these proteinaceous filaments exhibit remarkable structure and functions, their potential to design bioinspired self-assembled systems has been overlooked. Here, we used atomic force microscopy (AFM) to explore the supramolecular organization and self-assembly of pili from the Gram-positive probiotic bacterium Lactobacillus rhamnosus GG (LGG). High-resolution AFM imaging of cell preparations adsorbed on mica revealed pili not only all around the cells, but also in the form of remarkable star-like structures assembled on the mica surface. Next, we showed that two-step centrifugation is a simple procedure to separate large amounts of pili, even though through their synthesis they are covalently anchored to the cell wall. We also found that the centrifuged pili assemble as long bundles. We suggest that these bundles originate from a complex interplay of mechanical effects (centrifugal force) and biomolecular interactions involving the SpaC cell adhesion pilin subunit (lectin-glycan bonds, hydrophobic bonds). Supporting this view, we found that pili isolated from an LGG mutant lacking hydrophilic exopolysaccharides show an increased tendency to form tight bundles. These experiments demonstrate that AFM is a powerful platform for visualizing individual pili on bacterial surfaces and for unravelling their two-dimensional assembly on solid surfaces. Our data suggest that bacterial pili may provide a generic approach in nanobiotechnology for elaborating functional supramolecular interfaces assembled from bioactive building blocks. 相似文献
787.
B. K. Rana A. K. Shukla R. Topno R. M. Tripathi V. D. Puranik 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(3):505-510
The study summarizes radiological characteristics of Banduhurang open cast mine which includes qualitative and quantitative behavior of 222Rn concentration, external gamma radiation level over the mine pit as well as in its adjoining environment, long-lived alpha (LLα) activity concentration associated with the respirable size of ore dust and assessment of dose to the mine workers in 2006–2008. The investigations reveal that geometric means (χg) of measured radon concentration were 36.39, 38.69, 26.64 and 24 Bq m?3 with respective geometric standard deviations (σg) were 1.52, 1.55, 1.36 and 1.68 Bq m?3 and χg of gamma absorbed dose rates were 0.54, 0.64, 0. 45 and 0.15 μGy h?1 with respective σg were 1.63, 1.53, 1.52 and 1.72 μGy h?1 over the mine pit, ore yard, waste yard and in the surrounding environment within a 10 km radius to the mine, respectively. The χg of LLα activity was observed to be 16 mBq m?3 with σg of 1.9 mBq m?3. The annual mean effective dose equivalent received by the member radiation workers of Banduhurang mine was estimated to 1.41 mSv y?1, which is about 7% of the prescribed dose limits of 20 mSv y?1. 相似文献
788.
A heparinase-producing fungus was isolated, and the strain was taxonomically characterized as Aspergillus flavus by morphophysiological and 26S rRNA gene homology studies. The culture produced intracellular heparinase enzyme, which was
purified 40.5-fold by DEAE-Sephadex A-50, CM-Sephadex C-50, and Sephadex G-100 column chromatography. Specific activity of
the purified enzyme was found to be 44.6 IU/μg protein and the molecular weight of native as well as reduced heparinase was
24 kDa, showing a monomeric unit structure. Peptide mass spectrum showed poor homogeneity with the database in the peptide
bank. The enzyme activity was maximum at 30 °C in the presence of 300 mM NaCl at pH 7.0. In the presence of Co2+, Mn2+ ions, and reducing agents (β-mercaptoethanol, dithiothreitol), enzyme activity was enhanced and inhibited by iodoacetic acid.
These observations suggested that free sulfohydryl groups of cysteine residues were necessary for catalytic activity of the
enzyme. The enzyme was also inhibited by histidine modifier, DEPC, which suggests that along with cysteine, histidine may
be present at its active site. The enzyme showed a high affinity for heparin as a substrate with K
m and V
max as 2.2 × 10−5 M and 30.8 mM min−1, respectively. The affinity of the enzyme for different glycosaminoglycans studied varied, with high substrate specificity
toward heparin and heparin-derived polysaccharides. Depolymerization of heparin and fractionation of the oligosaccharides
yielded heparin disaccharides as main product. 相似文献
789.
Preparation and nonlinear characterization of zinc selenide nanoparticles embedded in polymer matrix
Nanocomposites of ZnSe nanoparticles embedded in polyvinyl alcohol (PVA) matrix have been prepared by in-situ synthesis. ZnSe/PVA nanocomposites are characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and UV/Vis spectra. The nanocomposite structure is confirmed by the blue-shift of the absorption edge. The nonlinear refractive index and two-photon absorption (TPA) coefficient are measured by the Z-scan technique using low power CW He–Ne laser light. The results show that the ZnSe nanocomposite films show large optical nonlinearity and the magnitude of the third-order nonlinear susceptibility χ(3) is calculated to be 2.62×13?11 m2/V2. 相似文献
790.