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231.
232.
Vijay Singh R.P.S. Chakradhar Isabelle Ledoux-Rak Laurent Badie Fabienne Pelle Svetlana Ivanova 《Journal of luminescence》2009,129(11):1375-1380
New near-infrared luminescent, monoclinic CaAl2O4:Er3+ phosphor was prepared by using the combustion route at furnace temperatures as low as 500 °C in a few minutes. Combustion synthesized phosphor has been well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive analysis of X-ray (EDAX) mapping studies. The luminescence spectra of Er3+-doped calcium aluminate were studied at UV (380 nm), vis (488 nm) and IR (980 nm) excitation. Upon UV and vis excitation, the CaAl2O4:Er3+ phosphor exhibits emission bands at ~523 nm and at ~547 nm, corresponding to transitions from the 2H11/2 and 4S3/2 erbium levels to the 4I15/2 ground state. A strong luminescence at 1.55 μm in the infrared (IR) region due to 4I13/2→4I15/2 transition has been observed in CaAl2O4:Er3+ phosphor upon 980 nm CW pumping. In the spectrum of IR-excited up-conversion luminescence, green (~523 and ~547 nm) and red (662 nm) luminescence bands were present, the latter associated with the 4F9/2→4I15/2 transitions of Er3+ ions. Both excited state absorption and energy transfer may be proposed as processes responsible for the population of the 4S3/2 and 4F9/2 erbium levels upon IR excitation. The mechanisms responsible for the up-conversion luminescence are discussed. 相似文献
233.
Balram Tripathi Y. K. Vijay F. Singh D. K. Avasthi S. Wate 《Indian Journal of Physics》2009,83(12):1659-1665
Iron doped CdS nanocrystals have been synthesized by using aqueous solution precipitation method. Samples of CdS:Fe have been
subjected to irradiation using C+6 (80 MeV) under of 1×1013 ions/cm2. For characterization, X-ray diffraction (XRD), Photoluminescence (PL) and Optical absorption studies have been performed.
The system has been found in hexagonal phase having particle size distribution 18–20 nm. Photoluminescence intensity has been
found to decrease, while optical band gap has been found to increase in irradiated samples. 相似文献
234.
Luttmann E Ensign DL Vaidyanathan V Houston M Rimon N Øland J Jayachandran G Friedrichs M Pande VS 《Journal of computational chemistry》2009,30(2):268-274
Implementation of molecular dynamics (MD) calculations on novel architectures will vastly increase its power to calculate the physical properties of complex systems. Herein, we detail algorithmic advances developed to accelerate MD simulations on the Cell processor, a commodity processor found in PlayStation 3 (PS3). In particular, we discuss issues regarding memory access versus computation and the types of calculations which are best suited for streaming processors such as the Cell, focusing on implicit solvation models. We conclude with a comparison of improved performance on the PS3's Cell processor over more traditional processors. 相似文献
235.
To address people's concerns of exogenous oxytocin (OT) administration to lactating bovines, a study was undertaken to (a) establish an enzyme immunoassay (EIA) for OT determination in milk, (b) quantify OT in milk of cows administered OT, and (c) study influence of pasteurization on OT stability in milk. A sensitive EIA validated according to the criteria of European Union—Decision 2002/657/EC was developed for OT in skim milk in an analytical range of 10-250 pg mL−1 with a decision limit (CCα) of 30 pg mL−1 and detection capability (CCβ) of 41.5 pg mL−1. Milk samples collected from cows (n = 38) administered either 25 or 50 IU OT prior to milking were investigated for the presence of OT. There was no significant difference among both groups with the mean concentrations of OT being 15.8 and 14.9 pg mL−1 for cows subjected to 25 and 50 IU OT administration, respectively. The OT levels in skim milk of control cows (n = 30; untreated) were basal (around 10 pg mL−1). All the analyzed milk samples were below the CCα value of 30 pg mL−1. Pasteurization of OT spiked milk samples at different temperature and sample holding conditions reduced the immunological activity of OT to 43% at 110 °C. However, no further decline occurred in the immunological activity with increased pasteurization temperature and time. It was concluded that the milk OT concentrations after OT administrations were minimal and below the assay decision limit. However, OT was quite stable to pasteurization in OT spiked milk. 相似文献
236.
Pamita Bhandari Neeraj Kumar Bikram Singh Ajai P. Gupta Vijay K. Kaul Paramvir S. Ahuja 《Chromatographia》2009,69(3-4):221-227
A liquid chromatography method was developed and validated for the determination of picroside-I and picroside-II in herbal preparations containing Picrorhiza kurroa as one of the ingradients. Resolution of picrosides was achieved on a reversed phase (C-18) endcapped bidentate column by using a mobile phase of acetonitrile: water (25:75 v/v). The detection of picrosides was carried out at 270 nm. The method was validated for precision, accuracy and robustness according to the International Conference on Harmonization (ICH) guidelines and is applicable for the quality control of preparations containing P. kurroa. Analysis of samples in forced degradation proved it to be applicable for stability evaluation. The linear regression analysis data showed good linear relationship (r 2 = 0.9999 ± 0.0010 for picroside-I and 0.9997 ± 0.0012 for picroside-II) in the concentration range of 0.4–4.0 μg. The limit of detection and quantification for picroside-I and picroside-II were recorded to be 28.1 and 73.1 ng and 85.2 and 221.5 ng, respectively. Satisfactory recovery results were observed from the herbal preparations (97.5–100.5%). Intra- and inter- day precision of the method was acceptable, with relative standard deviation (%RSD) values in the range of 0.04–1.16% and 0.03–0.27%, respectively. 相似文献
237.
Patrick Guertler Vijay Paul Christiane Albrecht Heinrich H. D. Meyer 《Analytical and bioanalytical chemistry》2009,393(6-7):1629-1638
To address food safety concerns of the public regarding the potential transfer of recombinant DNA (cry1Ab) and protein (Cry1Ab) into the milk of cows fed genetically modified maize (MON810), a highly specific and sensitive quantitative real-time PCR (qPCR) and an ELISA were developed for monitoring suspicious presence of novel DNA and Cry1Ab protein in bovine milk. The developed assays were validated according to the assay validation criteria specified in the European Commission Decision 2002/657/EC. The detection limit and detection capability of the qPCR and ELISA were 100 copies of cry1Ab μL?1 milk and 0.4 ng mL?1 Cry1Ab, respectively. Recovery rates of 84.9% (DNA) and 97% (protein) and low (<15%) imprecision revealed the reliable and accurate estimations. A specific qPCR amplification and use of a specific antibody in ELISA ascertained the high specificity of the assays. Using these assays for 90 milk samples collected from cows fed either transgenic (n?=?8) or non-transgenic (n?=?7) rations for 6 months, neither cry1Ab nor Cry1Ab protein were detected in any analyzed sample at the assay detection limits. Figure
Schematic formats for quantitative real-time PCR and ELISA for the quantification of cry1Ab DNA and Cry1Ab protein 相似文献
238.
239.
Pawar VD Bettigeri S Weng SS Kao JQ Chen CT 《Journal of the American Chemical Society》2006,128(19):6308-6309
An unprecedented vanadyl(V) methoxide complex 4 derived from 3,5-dibromo-N-salicylidene-l-tert-leucinate enables highly enantioselective aerobic oxidations of alpha-hydroxyphosphonates at ambient temperature with selectivity factors ranging from 3 to >99. 相似文献
240.
In this work, molecular dynamics simulation is performed to study the density and surface tension of water for a range of temperatures from 300 to 600 K. The extended simple point charge interaction potential for water is used. The particle-particle particle-mesh method, which automatically includes untruncated long-range terms, is used for the Lennard-Jones and the Coulombic terms. The results show that the long-range correction for the Lennard-Jones term is very important for the calculation of surface tension. It is found that the calculated density and surface tension of water fit well with experimental data for temperatures less than 500 K. Near the critical temperature, the simulation results are off from the experimental data. 相似文献