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341.
R. R. Chitnis P. K. Wattal A. Ramanujam P. S. Dhami V. gopalakrishnan A. K. Bauri A. Banerji 《Journal of Radioanalytical and Nuclear Chemistry》1999,242(3):727-730
The sorption and migration of radiostrontium in a calcareous soil from Yu Zhong county of Gansu province (China) was studied
using batch and column experiments. Sorption isotherms, breakthrough curves and concentration profiles for the untreated soil
and the soil treated to remove CaCO3 were determined, respectively. It was found that radiostrontium is a relatively mobile nuclide in calcareous soil and removal
of CaCO3 from the soil slightly increases the retention ability for radiostrontium. The breakthrough curves were fitted to the analytical
solution of a one-dimensional convection-dispersion transport model that assumes a reversible linear isotherm. Good agreement
was obtained between the measured and predicted concentration profiles. 相似文献
342.
Anupam Bhim Shreya Sasmal Jagannatha Gopalakrishnan Srinivasan Natarajan 《化学:亚洲杂志》2020,15(19):3104-3115
The synthesis, structure, optical and photocatalytic studies of a family of compounds with the general formula, BiMXO5; M=Mg, Cd, Ni, Co, Pb, Ca and X=V, P is presented. The compounds were prepared by regular solid‐state reaction of constituents in the temperature range of 720–810 °C for 24 h. The compounds were characterized by powder X‐ray diffraction (PXRD) methods. The Rietveld refinement of the PXRD patterns have been carried out to establish the structure. The optical absorption spectra along with the colors in daylight have been explained employing the allowed d‐d transition. In addition, the observed colors of some of the V5+ containing compounds were explained using metal‐to‐metal charge transfer (MMCT) from the partially filled transition‐metal 3d orbitals to the empty 3d orbitals of V5+ ions. The near IR (NIR) reflectivity studies indicate that many compounds exhibit good NIR reflectivity, suggesting that these compounds can be employed as ‘cool pigments’. The experimentally determined band gaps of the prepared compounds were found to be suitable to exploit them for visible light activated photocatalysis. Photocatalytic C?C bond cleavage of alkenes and aerobic oxidation of alcohols were investigated employing visible light, which gave good yields and selectivity. The present study clearly demonstrated the versatility of the Paganoite family of compounds (BiMXO5) towards new colored inorganic materials, visible‐light photocatalysts and ‘cool pigments’. 相似文献
343.
In contrast to traditional multistep synthesis, modern organic synthesis extensively depends on the direct functionalization of unactivated C?H bonds for the construction of various C?C and C‐heteroatom bonds in atom‐ and step‐economic manner. Common aliphatic substrates, e. g. carboxylic acids and their synthetic equivalents, are regiospecifically functionalized based on either a directed approach, in which the polar directing group assists to functionalize a specific C?H bond positioned at β‐ and γ‐carbon centers, or a non‐directed approach typically leading to α‐functionalization. While numerous reviews on catalytic C?H functionalization have appeared, a concise review on the direct C(sp3)?H heterofunctionalization of carboxylic acid synthons with Group 16 elements has been awaited. The recent advances on the direct oxy‐functionalization and chalcogenation of aliphatic carboxylic acid synthons enabled by transition metal, organo‐ and photocatalysts are described herein. 相似文献
344.
Gupta Anupam Kumar Amit Nagarajan Viswanath Shen Xiangkun 《Mathematical Programming》2022,192(1-2):597-630
Mathematical Programming - We study stochastic combinatorial optimization problems where the objective is to minimize the expected maximum load (a.k.a. the makespan). In this framework, we have a... 相似文献
345.
Perjes and Israel and Wilson have given independently a new class of solutions of the sourcefree Einstein-Maxwell equations, which can be interpreted as the external gravitational and electromagnetic fields of a spinning source with unit specific charge. Starting from Zipoy's solutions in oblate and prolate spheroidal coordinates for the source-free gravitational field we generate some axially symmetric stationary solutions of the source-free Einstein-Maxwell equations by using Perjes' method. All these solutions become Euclidean at infinity. The asymptotic behavior and the singularity of the solutions are studied in order to gain some insight into the nature of the source. The solution in prolate spheroidal coordinates is found to contain closed timelike lines. 相似文献
346.
Arshpreet Kaur Sapna Singla Anupam Dixit G. P. Kothiyal K. Krishnan 《Phase Transitions》2013,86(8):759-777
Lead silicate glasses containing 40–65?mol% of PbO were prepared at two melt-quenching rates and characterized by X-ray diffraction, UV-Visible absorption spectroscopy, density, microhardness, thermo-mechanical analysis, differential scanning calorimetry and Raman scattering studies. On increasing the PbO concentration, density increases, glass transition temperature decreases and the optical absorption edge shifts towards longer wavelength. An intense optical absorption band was observed just below the absorption edge in glasses with 55?mol% and higher concentration of PbO. Dilatometric measurements show an unusual property that glasses do not show any abrupt increase in volume near the glass transition temperature but transform directly into the liquid state. Raman spectroscopy confirmed that the concentration of SiO4 tetrahedra containing one or more NBOs increase with PbO mol%. Devitrification studies on lead silicate glasses found that samples with 40–45?mol% of PbO do not crystallize, whereas samples with higher PbO concentration produce multiple crystalline phases like PbSiO3, Pb33Si24O81, Pb2SiO4 and Pb3Si2O7 on heat treatment. 相似文献
347.
348.
Anupam Saha Somdeb Jana Tarun K. Mandal 《Journal of polymer science. Part A, Polymer chemistry》2016,54(18):3019-3031
Peptide–polymer conjugates are versatile class of biomaterials composed of a peptide block covalently linked with a synthetic polymer block. This report demonstrates the synthesis of peptide‐poly(tert‐butyl methacrylate) (Peptide‐PtBMA) conjugates of varying molecular weights via a “grafting from” atom transfer radical polymerization (ATRP) technique using as‐synthesized peptide‐based initiator in toluene. Peptide‐PtBMA conjugate is soluble in many organic solvents and undergoes self‐assembly into micro/nanospheres in DMF/THF as observed from both FESEM and DLS results. The conjugate micro/nanospheres are nothing but the composite micelles formed by the secondary aggregation of primary micelles generated initially in these organic solvents. The hydrolysis of tert‐butyl groups of Peptide‐PtBMA conjugate leads to the formation of peptide‐poly(methacrylic acid) (Peptide‐PMA) conjugate. The circular dichroism (CD) analysis exhibits the presence of β‐sheet conformation of peptide moiety in synthesized conjugates. The formed Peptide‐PMA conjugate is soluble in water and owing to its amphiphilic character, the conjugate molecules self‐assemble into spherical micelles as well as worm‐like micelles upon increasing the concentration of conjugate in water. However, the sodium salt of Peptide‐PMA conjugates (Peptide‐PMAS) self‐assembles into only spherical swollen micelles in water at higher (pH ~10). The critical aggregation concentrations (CACs) of both Peptide‐PMA and Peptide‐PMAS micelles are measured by fluorescence spectroscopy. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3019–3031 相似文献
349.
Jonathan D. Yuen Mingfeng Wang Jian Fan Dennis Sheberla Moureen Kemei Natalie Banerji Mariateresa Scarongella Sebastian Valouch Toan Pho Rajeev Kumar Eneida C. Chesnut Michael Bendikov Fred Wudl 《Journal of polymer science. Part A, Polymer chemistry》2015,53(2):287-293
The first observation that PBBTPD, a low bandgap, ambipolar conjugated donor-acceptor (DA) polymer based on benzobisthiadiazole (BBT), possesses an open-shell singlet ground state as well as a thermally accessible triplet state is described. Similarly, interesting electronic behavior in semiconducting organic DA oligomers based on BBT is also observed. Theoretical predictions have suggested that such behavior is due to the biradicaloid character of BBT and we provide experimental evidence indicating that these predictions are correct. Furthermore, the open shell character strengthens as the conjugation length increases, as observed in the BBT-based polymer, PBBTPD. We show that this biradicaloid structure is observed in each BBT moiety along the chain and that therefore PBBTPD is in fact a polyradicaloid. This observation will most likely aid in the development of better n-type polymeric acceptors for organic semiconductor applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 287–293 相似文献
350.
Avijit Banerji Debasish Bandyopadhyay Kumar R. Sur Julie Banerji 《Tetrahedron letters》2005,46(41):7033-7035
Aromatic trifluoroacetyl derivatives on treatment with single electron transfer (SET) reagent, sodium naphthalenide, yield symmetrical defluorinated dimers, whereas for aliphatic trifluoroacetyl compounds the reaction usually fails. Investigations have been made for different substituents as well as for similar types of chloro and bromo compounds to establish the scope of the reaction. 相似文献