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101.
Mukhopadhyay MK Jiao X Lurio LB Jiang Z Stark J Sprung M Narayanan S Sandy AR Sinha SK 《Physical review letters》2008,101(11):115501
Changes to the structure of polystyrene melt films as measured through the spectrum of density fluctuations have been observed as a function of film thickness down to the polymer radius of gyration (Rg). Films thicker than 4Rg show bulklike density fluctuations. Thinner films exhibit a peak in S(q) near q=0 which grows with decreasing thickness. This peak is attributed to a decreased interpenetration of chains resulting in an enhanced compressibility. Measurements were made using small angle x-ray scattering in a standing wave geometry designed to enhance scattering from the interior of the film compared to interface scattering. 相似文献
102.
Vinay Kiran Narayanan Balaji Bhavesh Babulal Gabani Manjuanth Bajantri Rajesh Chandran Abhishek Dixit Nuggehally R. Srinivas Ramesh Mullangi 《Biomedical chromatography : BMC》2020,34(9):e4879
We developed and validated a simple, sensitive, selective, and reliable LC–MS/MS–ESI method for the direct quantitation of lumefantrine (LFN) enantiomers [(−)-LFN and (+)-LFN] in mice plasma as per regulatory guideline. LFN enantiomers and carbamazepine (internal standard) were extracted from mice plasma using Strata X SPE (solid-phase extraction) cartridges. Good resolution between enantiomers was achieved on a Chiralpak IA-3 column using an isocratic mobile phase (0.1% of diethyl amine in methanol), which was delivered at a flow rate of 0.8 mL/min. Detection and quantitation were performed using multiple reaction monitoring mode following the transitions m/z 530.27 → 512.30 and 237.00 → 194.00 for LFN enantiomers and the internal standard, respectively, in the positive-ionization mode. The proposed method provided accurate and reproducible results over the linearity range of 2.39–895 ng/mL for each enantiomer. The intra- and inter-day precisions were in the range of 1.03–6.14 and 6.36–8.70 and 2.03–4.88 and 5.82–11.5 for (−)-LFN and (+)-LFN, respectively. Both (−)-LFN and (+)-LFN were found to be stable under different stability conditions. The method was successfully used to delineate stereoselective pharmacokinetics of LFN enantiomers in mice after an oral administration of rac-LFN (20 mg/kg). The pharmacokinetic results indicated that the disposition of LFN enantiomers was stereoselective in mice. 相似文献
103.
Premchand V. P. Balaram Bipin Mani Ajith K. Narayanan M. D. Sajith A. S. 《Nonlinear dynamics》2022,110(1):573-588
Nonlinear Dynamics - Optimisation procedures for nonlinear vibrating systems are made cumbersome due to the fact that the regimes of periodic response are not known beforehand. Moreover, such... 相似文献
104.
Analytical and numerical solution of an $$\varvec{n}$$n-term fractional nonlinear dynamic oscillator
Nonlinear Dynamics - This work presents a novel method for the analytical and numerical solution of an n-term fractional nonlinear dynamical system. Two simple methods, commonly known to vibration... 相似文献
105.
Mithilesh Kumar Nayak Jessica Stubbe Dr. Nicolás I. Neuman Dr. Ramakirushnan Suriya Narayanan Sandipan Maji Prof. Dr. Carola Schulzke Prof. Vadapalli Chandrasekhar Prof. Dr. Biprajit Sarkar Dr. Anukul Jana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4425-4431
This work presents a stepwise reversible two-electron transfer induced hydrogen shift leading to the conversion of a bis-pyrrolinium cation to an E-diaminoalkene and vice versa. Remarkably, the forward and the reverse reaction, which are both reversible, follow two completely different reaction pathways. Establishing such unprecedented property in this type of processes was possible by developing a novel synthetic route towards the starting dication. All intermediates involved in both the forward and the backward reactions were comprehensively characterized by a combination of spectroscopic, crystallographic, electrochemical, spectroelectrochemical, and theoretical methods. The presented synthetic route opens up new possibilities for the generation of multi-pyrrolinium cation scaffold-based organic redox systems, which constitute decidedly sought-after molecules in contemporary chemistry. 相似文献
106.
107.
108.
Spatial and temporal in situ evolution of the concentration profile during casein micelle ultrafiltration probed by small-angle X-ray scattering 总被引:1,自引:0,他引:1
David C Pignon F Narayanan T Sztucki M Gésan-Guiziou G Magnin A 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):4523-4529
Understanding the mechanisms involved in structural development in the vicinity of membrane constitutes a considerable challenge in the improvement of ultrafiltration process in industrial applications. In situ small-angle X-ray scattering (SAXS) performed with custom-made ultrafiltration cell has permitted the structural arrangement to be probed and concentration profiles to be obtained in deposited layers during frontal filtration of casein micelle suspension. SAXS allowed the structure of the accumulated layers of casein micelles between 280 microm and 1 mm from the membrane surface to be followed at length scales from a few nanometers to about 100 nm. These results have been combined with hydrodynamic measurements (permeation flux) and rheological investigations. Under frontal filtration, the time dependence of concentration at different distances from the membrane surface has been obtained. This temporal evolution is marked by an exponential increase of the concentration followed by a slower growth which has been associated with a change in the rheological behavior of the suspension from Newtonian to shear thinning behavior. 相似文献
109.
Recently, a sequence for heteronuclear dipolar decoupling in solid-state NMR, namely SWf-TPPM, was introduced by us. Under magic-angle spinning (MAS), the decoupling efficiency of the sequence was unaffected over a range of values for various experimental parameters such as the pulse length, pulse phase, and 1H resonance offset. We here demonstrate its use in multiple-quantum (MQ) and high-resolution (HR) MAS experiments. This sequence further improves the MQMAS spectra compared to the earlier reported decoupling sequences with improved immunity to any missets of the pulse length, pulse phase and decoupler offset. In contrast, for HRMAS, the simple CW scheme is as efficient as any of the decoupling schemes that were studied. 相似文献
110.
Varun A. Baheti Sarfaraj Islam Praveen Kumar Raju Ravi Ramesh Narayanan Dong Hongqun 《哲学杂志》2016,96(1):15-30
A strong influence of Ni content on the diffusion-controlled growth of the (Cu,Ni)3Sn and (Cu,Ni)6Sn5 phases by coupling different Cu(Ni) alloys with Sn in the solid state is reported. The continuous increase in the thickness ratio of (Cu,Ni)6Sn5 to (Cu,Ni)3Sn with the Ni content is explained by combined kinetic and thermodynamic arguments as follows: (i) The integrated interdiffusion coefficient does not change for the (Cu,Ni)3Sn phase up to 2.5 at.% Ni and decreases drastically for 5 at.% Ni. On the other hand, there is a continuous increase in the integrated interdiffusion coefficient for (Cu,Ni)6Sn5 as a function of increasing Ni content. (ii) With the increase in Ni content, driving forces for the diffusion of components increase for both components in both phases but at different rates. However, the magnitude of these changes alone is not large enough to explain the high difference in the observed growth rate of the product phases because of Ni addition. (iv) Kirkendall marker experiments indicate that the Cu6Sn5 phase grows by diffusion of both Cu and Sn in the binary case. However, when Ni is added, the growth is by diffusion of Sn only. (v) Also, the observed grain refinement in the Cu6Sn5 phase with the addition of Ni suggests that the grain boundary diffusion of Sn may have an important role in the observed changes in the growth rate. 相似文献