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11.
Kallol K. Ghosh Sunita Bal Manmohan L. Satnami P. Rodriguez‐Dafonte Rama M. Palepu 《Journal of Dispersion Science and Technology》2013,34(3):349-355
Pseudo‐first‐order rate constants have been determined for the nucleophilic substitution reactions of p‐nitrophenyl acetate with oxalo, malono, and succinodihydroxamate ions (?ONHC(O)(CH2)nC(O)NHO?) in phosphate buffer (pH=7.9) at 27°C. The rate data of the reaction revealed that the nucleophilic reactivity sequence of these hydroxamate ions is generally ODHA>MDHA>SDHA. The kobs value increases upon addition of cationic surfactants to the reaction medium which is typical behavior of micelle‐assisted bimolecular reactions. The pseudo‐phase ion exchange model has been successfully applied to determine binding constant. 相似文献
12.
Fritzsch like mass matrices with non-zero 22-elements both in U sector and D sector have been investigated in the context
of latest data regardingm
t
phys
, |V
ub|, |V
cb|, |V
td| and |V
ts|. Unlike several other phenomenological models, the present model not only accommodates the value ofm
t
phys
in the range 150–240 GeV, encompassing the CDF and D0 values, but is also able to reproduce |V
cb| ≊0.040 and |V
ub/Vcb| = 0.08±0.02 and |V
td| is predicted to lie in the range 0.005–0.014. Further, the angles of the unitarity triangle, related to the CP-violating
asymmetries, are calculated to be in the ranges −1.0⩽sin2α⩽−0.1, 0.6 ⩽sin2α⩽1.0 and 0.48⩽sin2β⩽0.56, which are in agreement
with other recent calculations. 相似文献
13.
Bhanushree Gupta Rahul Sharma Namrata Singh Yevgen Karpichev Manmohan L. Satnami Kallol K. Ghosh 《Journal of Physical Organic Chemistry》2013,26(8):632-642
Kinetic studies of the reactions of tertiary oximes (monoisonitroso acetone; MINA and butane 2,3 dione monooxime; BDMO) with some carboxylate (p‐nitrophenyl acetate and p‐nitrophenyl benzoate), phosphate (p‐nitrophenyl diphenyl phosphate and bis (2,4‐dinitrophenyl) phosphate) and sulfonate (p‐nitrophenyl p‐toluene sulphonate) esters in gemini surfactants have been conducted. The observed first‐order rate constant versus surfactant profiles show micelle‐assisted bimolecular reactions involving interfacial ion exchange between bulk aqueous media and micellar pseudophase. Experimental results showed that MINA exhibited better nucleophilic activity towards ester cleavage than BDMO. Pseudophase model has been applied in order to determine micellar second‐order rate constants and binding constants. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
14.
The spruce budworm model is one of the interesting single species reaction-diffusion problems describing insect dispersal behavior. In this paper, we investigate a two-dimensional model with linear diffusion dependence and a convective wind. This system has been successfully solved using an operator splitting method for various domains and initial conditions. The numerical results show that populations can grow and diffuse in such a way as to produce steady state outbreak populations or steady state inhomogeneous spatial patterns in which they aggregate with low population densities. 相似文献
15.
A diffusive epidemic model for H1N1 influenza is formulated with a view to gain basic understanding of the virus behavior. All newborns are assumed to be susceptible. Mortality rate for infective individuals in the population is assumed to be greater than natural mortality rate. Latent, infectious and immune periods are assumed to be constants throughout this study. The numerical solutions of this model are carried out under three different initial populations distribution. In order to investigate the effect of the disease transmission coefficient on the spread of disease, β is taken to be constant as well as a function of seasonally varying time t and a function of spatial variable x . The threshold quantity (R0) that governs the disease dynamics is derived. Numerical simulation shows that the system supports the existence of sustained and damped oscillations depending on initial populations distribution, the disease transmission rate and diffusion. 相似文献
16.
Heteroatom‐Guided,Palladium‐Catalyzed,Site‐Selective CH Arylation of 4H‐Chromenes: Diastereoselective Assembly of the Core Structure of Myristinin B through Dual CH Functionalization
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Govind Goroba Pawar Virendra Kumar Tiwari Dr. Himanshu Sekhar Jena Dr. Manmohan Kapur 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9905-9911
A highly site‐selective, heteroatom‐guided, palladium‐catalyzed direct arylation of 4H‐chromenes is reported. The C?H functionalization is driven not only by the substituents and structure of the substrate but also by the coupling partner being used. The diastereoselective assembly of the core structure of Myristinin B has been achieved by using a dual C?H functionalization strategy for regioselective direct arylation. 相似文献
17.
Fujiwara–Moritani Reaction of Weinreb Amides using a Ruthenium‐Catalyzed C−H Functionalization Reaction
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The ruthenium‐catalyzed Fujiwara–Moritani reaction (oxidative‐Heck reaction) of Weinreb amides is reported herein. The reaction affords exclusively ortho‐C?H olefination products, has excellent substrate scope and tolerates halogen functionalities, which increase the synthetic utility of the method. A variety of activated olefins as well as styrenes can be employed as coupling partners. 相似文献
18.
Chandrakuntal K Thomas NM Kumar PG Laloraya M Laloraya MM 《Photochemistry and photobiology》2006,82(5):1358-1364
The photoreceptive extreme tip of the wheat coleoptile exhibits intense green-yellow fluorescence under UV light, suggesting the presence of UV-absorbing materials. Fluorescence spectra of the intact coleoptile tip and tip homogenate showed the presence of the known photoreceptor pigments flavin and carotene, and a preponderance of phenolic compounds. Absorption spectra and fluorescence spectra of various phenolic compounds showed close overlap with the absorption and fluorescence spectra of the wheat coleoptile tip homogenate. Fluorescence spectra of several phenolic compounds showed close overlap with the absorption bands of flavin, carotene and pterine, suggesting possible energy transduction from phenols to these photoreceptors. Excitation of gentisic acid and ferulic acid with 340 nm light in the presence of flavin showed enhancement of flavin fluorescence in a concentration- and viscosity-dependent fashion, indicating fluorescence resonance energy transfer between them and riboflavin. Furthermore, several phenolic compounds tested generated superoxide anion on excitation at 340 nm, suggesting that superoxide-dependent signal cascades could operate in a polyphenol-mediated pathway. Phenolic compounds thus may act as accessory photoreceptors bringing about excitation energy transfer to the reactive photoreceptor molecules, or they may take over the function of the normal photoreceptor in genetic mutations lacking the system, or both processes may occur. The responses of plants to UV-B and UV-A light in mutants may be explained in terms of various phenolics acting as energy transducers in photoreceptor functioning. 相似文献
19.
[reaction: see text] A new approach to complex chiral diols and polyols is described utilizing a tandem hydroboration/Suzuki cross-coupling reaction. This method utilizes the versatility of a glycolate-derived chiral template. 相似文献
20.
The fully functionalized core structure of the macrolactone queenslandon was prepared using a novel strategy consisting of a glycolate aldol reaction and hydroboration of the derived enol ether 17 followed by Suzuki cross-coupling with an iodostyrene. After conversion of the cross-coupling product to the seco acid 22, Mitsunobu macrolactonization and protecting group manipulations led to the queenslandon model 5. [structure: see text] 相似文献