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311.
Summary. A novel process for the one-step chemoselective conversion of alkyl halides into dithiocarbamates as protected amines was
developed using benzyltrimethylammonium hydroxide (Triton-B) in presence of carbon disulfide. Thus, dithiocarbamates of different
amines were prepared in very good to excellent yields. This protocol is mild, chemoselective, and efficient compared to other
methods.
Present address: Institute of Organic and Biomolecular Chemistry, Georg–August University, D-37077 G?ttingen, Germany 相似文献
312.
Mathematical modeling of the molar concentrations profile of ethanol, acetaldehyde and ethyl acetate inside the catalyst particle is presented. This kinetic mechanism is based on the system of non-linear reaction diffusion equations. Modified Adomian decomposition method is employed to derive the general analytical expressions of molar concentrations of ethanol, acetaldehyde and ethyl acetate for all possible values of the parameters Φi, γi and αi (i = 1, 2, 3). Analytical results are compared with the numerical results, a satisfactory agreement is noted. Valid and invalid region of the solution for all concentrations are provided. These analytical results are useful to understand the behavior of the system. 相似文献
313.
Sumit Kumar Ramovatar Meena R. Paulraj 《Applied biochemistry and biotechnology》2016,180(7):1257-1275
Titanium-dioxide nanoparticles (TNP) are used in various consumable goods. Evidence has demonstrated the cytotoxicity of TNPs, but exact mechanism is yet to be elucidated. The present study has been aimed at finding out the mechanism of TNP-induced toxicity in biological system. Different doses of anatase-TNPs administrated intravenously to Wistar rats for once a week for 1 month and properties of TH cells, macrophages, cytokines secretion, oxidative damage, apoptotic pathway, and hematological and pathological changes were investigated as downstream events of TNP-mediated cytotoxicity. Result suggests that TNPs induce TH1 and TH2 response as measured by immunophenotyping (interferon gamma (IFN-γ) and interleukin (IL)-4) of TH cells, causing induction of M1 (nitric oxide (NO), nitric oxide synthase (iNOS), NF-kappaB (NF-κB), cyclooxygenase-2 (COX-2), IL-1, IL-6, and TNF-α) and M2 (Arg-1, Ym1) macrophages response. At lower dose, TH1 or M1 response counteracted by TH2 or M2 response, resulting in insignificant oxidative damage. However, with increasing dose of TNPs, the M1 response was increased over M2 response resulting in significant tissue damage. The M1-induced inflammatory response was found to cause DNA and chromosomal damage resulting apoptosis induction via upregulation of Bax/Bcl-2 ratio and subsequent loss of mitochondrial membrane potential and cyto c release in splenocytes. The TNP-led inflammatory response also causes damage at different tissue levels. 相似文献
314.
The shear stability of drag reducing polymer-polymer and polymer-fibre mixtures has been studied at a Reynolds number of 14,000 using a turbulent flow rheometer. The ratio of the drag reduction at a particular pass number to the initial drag reduction has been determined for the mixtures at various pass numbers and compositions in order to determine the effect of composition on the shear stability of the mixtures.It has been found in both cases that when there is a drastic difference in the shear stabilities of the constituents of the mixtures, the incorporation of a small amount of the less shear stable drag reducing agent reduces the shear stability drastically. On the other hand, when the shear stability of the constituents are of the same order, there is only a proportional change in the shear stability of the mixtures on addition of one component to the other. A correlation between the decay coefficient of the mixture (R
M
), the decay coefficients of the constituents (R
1
andR
2
) and the weight fractions of the mixture components (W
1 andW
2) is suggested. An efficacious method for preparing asbestos fibre stock suspensions is also described. 相似文献
315.
Balram Meena Sunil Mehenderge D. D. Rao S. Venkataraman A. G. Hegde 《Journal of Radioanalytical and Nuclear Chemistry》2012,294(2):237-240
Ten fresh water samples of wells and rivers from the environment of Tarapur Maharashtra Site were analyzed to evaluate and establish the fall out level of 137Cs activity concentration using large volume of water samples. A radiochemical separation method suitable for the analysis of large volume of water sample based on the adsorption of Cs isotopes on coated acrylic fibres was standardized. 134Cs isotope was used for monitoring the radiochemical recovery of the analysis. Radiochemical recovery was obtained in the range of 74?C98% for a sample volume of 250?L or more. The fall out level 137Cs concentration in river/dam water was found to be in the range of 0.205 to 0.268?mBq?L?1. The fall out level annual effective dose through water ingestion pathway for a member of public was evaluated to be 2.27?×?10?9?Sv. 相似文献
316.
N. Kumar S. S. Chaturvedi S. K. Jha 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):95-101
A radiation dose assessment exercise was carried out for the Ipomea batata, Allium sativum, Dacaus carota, and Solanum tuberosum due to naturally available radionuclide 40K, 238U and 232Th in the Domiasiat area of Meghalaya. The concentration of radionuclides in biota as well as corresponding soil was measured
by precipitation method using NaI detector for continuous 12 months. Transfer factor was calculated and was, for 40K(3.96E−05, 3.40E−05, 3.40E−05, 2.70E−05), for 232Th(3.94E−05, 3.20E−05, 3.20E−054.93E−05), for 238U(3.60E−05, 3.89E−05, 3.85E−054.57E−05), respectively in each biota due to each radionuclide. The point source dose distribution
(source ↔ target) hypotheses was applied for the consideration of absorbed fraction. The generated data were modeled using
the FASSET method and obtained dose was 8.42E−03, 8.36E−03, 7.78E−03, 7.74E−03 μGy h−1, respectively and finally compared with the IAEA and UNSCEAR dataset for screening level dose for terrestrial biota. 相似文献
317.
The system of coupled nonlinear diffusion equations are solved analytically for the transport and kinetics of electrons and
reactant in the layer of a modified electrode. Analytical expressions of concentrations of mediator and substrate are presented
using Homotopy perturbation method. A simple expression of electrochemical rate constant K
ME+ is also obtained for all values of reaction parameters. The available limiting case results are compared with our results
and are found to be in good agreement. 相似文献
318.
R. T. Pardasani P. Pardasani V. Chaturvedi S. K. Yadav A. Saxena I. Sharma 《Heteroatom Chemistry》2003,14(1):36-41
A cyclic secondary α‐amino acid, viz. L ‐proline, reacts with isatin derivatives via decarboxylative azomethine ylide formation and subsequent cycloaddition with various dipolarophiles to give cycloadducts in moderate to good yield. Theoretical studies have been performed to study the stereochemistry of the products formed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:36–41, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10063 相似文献
319.
Mazaahir Kidwai Preeti Misra Kumar R. Bhushan Rajendra K. Saxena Meena Singh 《Monatshefte für Chemie / Chemical Monthly》2000,12(1):937-943
The reaction of heterocyclic acids with 7-amino-cephalosporanic acid adsorbed on basic alumina under microwave irradiation afforded the N-acylated cephalosporin analogues in satisfactory yield. All compounds were tested for their antibacterial activity; some of them showed significant antibacterial properties. Cefotaxime and cephalothin were used as reference drugs. 相似文献
320.
M F Insana T J Hall P Chaturvedi C Kargel 《The Journal of the Acoustical Society of America》2001,110(6):3243-3251
Acoustic properties of two types of soft tissue-like media were measured as a function of compressive strain. Samples were subjected to uniaxial strains up to 40% along the axis of the transducer beam. Measurements were analyzed to test a common assumption made when using pulse-echo waveforms to track motion in soft tissues--that local properties of wave propagation and scattering are invariant under deformation. Violations of this assumption have implications for elasticity imaging procedures and could provide new opportunities for identifying the sources of backscatter in biological media such as breast parenchyma. We measured speeds of sound, attenuation coefficients, and echo spectra in compressed phantoms containing randomly positioned scatterers either stiffer or softer than the surrounding gelatin. Only the echo spectra of gel media with soft scatterers varied significantly during compression. Centroids of the echo spectra were found to be shifted to higher frequencies in proportion to the applied strain up to 10%, and increased monotonically up to 40% at a rate depending on the scatterer size. Centroid measurements were accurately modeled by assuming incoherent scattering from oblate spheroids with an eccentricity that increases with strain. While spectral shifts can be accurately modeled, recovery of lost echo coherence does not seem possible. Consequently, spectral variance during compression may ultimately limit the amount of strain that can be applied between two data fields in heterogeneous media such as lipid-filled tissues. It also appears to partially explain why strain images often produce greater echo decorrelation in tissues than in commonly used graphite-gelatin test phantoms. 相似文献