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31.
Sagar Suman Panda Khusbu Sharma Bijeta Mohanty Ravi Kumar Venkata Varaha Bera Sasmita Kumari Acharjya Sarwar Beg 《液相色谱法及相关技术杂志》2017,40(19):951-958
An ultrafast liquid chromatographic bioanalytical method was developed and validated for the determination of telaprevir in Wistar albino rat serum. Principles of quality by design (QbD) were implemented for enhancing the bioanalytical liquid–liquid extraction of telaprevir from rat serum. A Box–Behnken design was utilized in the studies by selecting extraction time, centrifugation speed, and vortex time as the critical method variables for evaluating their effect on the critical analytical attribute, i.e., %recovery of telaprevir. Chromatographic separation was achieved within a run time of 10?min using a C-18 column and mobile phase comprising of methanol:borate buffer of pH 9 (90:10 v/v) flowing at 1.2?mL/min. Photodiode array detection was performed at 270?nm. Results of validation studies were satisfactory. The method was linear over a concentration of 25–10,000?ng/mL. Limit of detection for the developed method was 10?ng/mL. Further, design of experiments (DoE) used for inter-day accuracy and precision study suggested superior method reliability. This integrated QbD- and DoE-based approach ensured the development of a validated and reliable analytical method for optimum bioanalysis of telaprevir in biological matrix. 相似文献
32.
Liang W Bera T Zhang X Gesquiere AJ Fang J 《Langmuir : the ACS journal of surfaces and colloids》2011,27(3):1051-1055
Long-range organization of molecular tilt azimuth is a striking feature in monolayers at the air-water interface. We show that the boojum and stripe textures of pentadecanoic acid (PDA) with the continuous variations of molecular tilt azimuth formed at the air-water interface at temperatures lower than room temperature can be preserved after being transferred to glass substrates at low dipping speeds. The long-range tilt order in the transferred boojums and stripes is resolved by frictional force microscopy at room temperature, suggesting that the tilt order is "frozen" through the interaction of PDA molecules with the glass surface. The transferred stripe structure can be used as a unique alignment layer to induce a continuously azimuthal orientation of nematic liquid crystals. 相似文献
33.
Bera MK Hommes P Reissig HU 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(42):11838-11843
Herein, we describe our attempts to systematically prepare a series of oligo(2-thienyl)-substituted pyridine derivatives. The crucial starting material, a β-alkoxy-β-ketoenamide, is easily available on a large scale by the reaction of lithiated methoxyallene with thiophene-2-carbonitrile and thiophene-2-carboxylic acid. This three-component reaction is followed by intramolecular cyclization to yield the suitably functionalized 2,6-di(2-thienyl)-substituted pyridine derivates. The two oxygen atoms allow the programmed activation of positions C-3, C-4, or C-5 of the pyridine ring to perform palladium-catalyzed coupling reactions with thiophene-2-boronic acid or 2-(tributylstannyl)thiophene, and alternatively, reductive removal of groups. With this concept, we were able to prepare five pyridine derivatives with 2-thienyl substituents in the 2,6-, 2,3,6-, 2,4,6-, 2,3,4,6-, and 2,3,5,6-positions. 2,3,4,5,6-Penta(2-thienyl)pyridine was not available with our methods. The UV/Vis and fluorescence spectra of all pyridines were recorded and showed a dependence on the substitution pattern and protonation state. For the protonated 2,3,5,6-tetra(2-thienyl)-substituted pyridine, a Stokes shift of about 180 nm with an emission at 515 nm was observed. 相似文献
34.
Structural properties, spectroscopic constants and the interaction between rare-gas atom and open and closed-shell iodine
atom of weakly bound van der Waals molecules have been studied in details using CCSD(T) method. The Lennard-Jones potential
is used to study the interaction and spectroscopic constants of the neutral and anionic systems. The spectroscopic constants
and the interacting force between the two atoms of RgI and RgI− (Rg = He, Ne and Ar) have been calculated using our method developed recently for the weakly bound molecule in Lennard-Jones
potential. The results have been compared with the theoretical and experimental data wherever available. Most of the spectroscopic
constants are first reported. 相似文献
35.
NO Reduction Over Noble Metal Ionic Catalysts 总被引:1,自引:0,他引:1
In last 40 years, catalysis for NO
x
removal from exhaust gas has received much attention to achieve pollution free environment. CeO2 has been found to play a major role in the area of exhaust catalysis due to its unique redox properties. In last several
years, we have been exploring an entirely new approach of dispersing noble metal ions in CeO2 and TiO2 for redox catalysis. We have extensively studied Ce1−x
M
x
O2−δ (M = Pd, Pt, Rh), Ce1−x−y
A
x
M
y
O2−δ (A = Ti, Zr, Sn, Fe; M = Pd, Pt) and Ti1−x
M
x
O2−δ (M = Pd, Pt, Rh, Ru) catalysts for exhaust catalysis especially NO reduction and CO oxidation, structure–property relation
and mechanism of catalytic reactions. In these catalysts, lower valent noble metal ion substitution in CeO2 and TiO2 creates noble metal ionic sites and oxide ion vacancy. NO gets molecularly adsorbed on noble metal ion site and dissociatively
adsorbed on oxide ion vacancy site. Dissociative chemisorption of NO on oxide ion vacancy leads to preferential conversion
of NO to N2 instead of N2O over these catalysts. It has been demonstrated that these new generation noble metal ionic catalysts (NMIC) are much more
catalytically active than conventional nano crystalline noble metal catalysts especially for NO reduction. 相似文献
36.
Milena Špírková Jelena Pavli?evi? Adam Strachota Rafa? Poreba Oskar Bera Ludmila Kaprálková Josef Baldrian Miroslav Šlouf Nada Lazi? Jaroslava Budinski-Simendi? 《European Polymer Journal》2011,47(5):959-972
Novel all-aliphatic polycarbonate-based polyurethane (PC-PU) elastomers, as well as PC-PU nanocomposites filled with organic-modified clays were synthesized, characterized and studied. It was found that they have very attractive mechanical properties (e.g., elongation at break between 600% and 800%). The prepared PC-PUs possess a distinctly segmented structure, which is the key prerequisite for their behavior as strong physical rubbery networks. All synthesized materials melt at elevated temperatures (between 110 and 200 °C) and hence can be processed like normal thermoplastics. The dispersion of the clay nanofiller was achieved by its one day swelling in the alcohol and a brief successive stirring. This procedure is very successful and leads to a partial exfoliation of the clay (documented by X-ray diffraction and TEM). The best nanocomposites with very good tensile properties, particularly with significantly increased moduli were obtained using the bentonite nanofiller. The study shows that the nanofiller interacts strongly with the hard domains and influences their melting temperature (DMTA and DSC), but it does not affect the glass transition temperature of soft domains. While Cloisite 15A was found to interact preferentially with the hard domains, the organic modified bentonite shows a strong interaction with both soft and hard segments, behaving as a blending agent. Hard domains in neat matrices, formed by hydrogen bonding of hard segments, were practically invisible by X-ray or TEM, but were successfully detected by AFM. Besides excellent mechanical properties, the prepared elastomers and their nanocomposites showed an interesting phase behavior (which was studied by combining DMTA and modulated DSC). 相似文献
37.
A nonenzymatic method for the selective detection and quantification of serum uric acid (UA) using 2-thiouracil (2-TU) tailored Au nanoparticles is developed. The H-bonding interaction of UA with functionalized Au nanoparticles brings instantaneous visible color change and paves the way for the visible sensing of UA. 相似文献
38.
Curt DeCaro Vidanage Nuwan Karunaratne Sambhunath Bera Laurence B. Lurio Alec R. Sandy Suresh Narayanan Mark Sutton John Winans Kirk Duffin Jon Lehuta Nicholas Karonis 《Journal of synchrotron radiation》2013,20(2):332-338
The technique of speckle visibility spectroscopy has been employed for the measurement of dynamics using coherent X‐ray scattering. It is shown that the X‐ray contrast within a single exposure can be related to the relaxation time of the intermediate scattering function, and this methodology is applied to the diffusion of 72 nm‐radius latex spheres in glycerol. Data were collected with exposure times as short as 2 ms by employing a resonant shutter. The weak scattering present for short exposures necessitated an analysis formalism based on the spatial correlation function of individual photon charge droplets on an area detector, rather than the usual methods employed for intensity correlations. It is demonstrated that this method gives good agreement between theory and experiment and thus holds promise for extending area‐detector‐based coherent scattering methods to the study of faster dynamics than previously obtainable. 相似文献
39.
Umbelliferyl sugars have been used to determine the lectin concentration in very dilute solution by fluorescence quenching methods. The Stern-Volmer plot of fluorescence quenching after considering ground-state complexation is obeyed by several sugars. As little as 1 μg of lectin (in 10 μl) and 250 nM of umbelliferyl sugars can be determined. This method offers a simple, non-destructive and rapid method for the determination of lectin activity. 相似文献
40.
V. K. Dixit K. S. Keerthi H. L. Bhat Parthasarathi Bera M. S. Hegde 《Applied Surface Science》2003,220(1-4):321-326
The growth of epitaxial InBixAsySb(1−x−y) layers on highly lattice mis-matched semi-insulating GaAs substrates has been successfully achieved via the traditional liquid phase epitaxy. Orientation and single crystalline nature of the film have been confirmed by X-ray diffraction. Scanning electron micrograph shows abrupt interface at micrometer resolution. Surface composition of Bi(x) and As(y) in the InBixAsySb(1−x−y) film was measured using energy dispersive X-ray analysis and found to be 2.5 and 10.5 at.%, respectively, and was further confirmed with X-ray photoelectron spectroscopy. Variation of the composition with depth of the film was studied by removing the layers with low current (20 μA) Ar+ etching. It was observed that with successive Ar+ etching, In/Sb ratio remained the same, while the As/Sb and Bi/Sb ratios changed slightly with etching time. However after about 5 min etching the As/Sb and Bi/Sb ratios reached constant values. The room temperature band gap of InBi0.025As0.105Sb0.870 was found to be in the range of 0.113–0.120 eV. The measured values of mobility and carrier density at room temperature are 3.1×104 cm2 V−1 s−1 and 8.07×1016 cm−3, respectively. 相似文献