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991.
Web‐spline‐based finite element approximation of some quasi‐newtonian flows: Existence‐uniqueness and error bound 下载免费PDF全文
Sudhakar Chaudhary V. V. K. Srinivas Kumar 《Numerical Methods for Partial Differential Equations》2015,31(1):54-77
This article deals with the web‐spline‐based finite element approximation of quasi‐Newtonian flows. First, we consider the scalar elliptic p‐Laplace problem. Then, we consider quasi‐Newtonian flows where viscosity obeys power law or Carreau law. We prove well‐posedness at the continuous as well as the discrete level. We give some error bounds for the solution of quasi‐Newtonian flow problem based on the web‐spline method. Finally, we provide the numerical results for the p‐Laplace problem. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq31: 54–77, 2015 相似文献
992.
A rapid and practical green route for the N-formylation of amines with formic acid using Amberlite IR-120 as a catalyst is described. This method provides an efficient and much improved modification over the reported methods in terms of yield, reaction time, and work-up procedure. A wide variety of substituents is tolerated, which is not the case for existing procedures. 相似文献
993.
Nickel-Impregnated Silica Nanoparticle Synthesis and Their Evaluation for Biocatalyst Immobilization
Reddy Shetty Prakasham G. Sarala Devi Chaganti Subba Rao V. S. S. Sivakumar T. Sathish P. N. Sarma 《Applied biochemistry and biotechnology》2010,160(7):1888-1895
In the present investigation, impact of nickel-impregnated silica paramagnetic particles (NSP) as biocatalyst immobilization
matrices was investigated. These nanoparticles were synthesized by sol–gel route using a nonionic surfactant block co polymer
[poly (ethylene glycol)-block-poly-(propylene glycol)-block-poly (ethylene glycol)]. Diastase enzyme was immobilized on these particles (enzyme-impregnated NSP) as model enzyme and
characterized using Fourier-transform infrared spectroscopy and X-ray crystallography. Analysis of enzyme-binding nature with
these nanoparticles at different physiological conditions revealed that binding pattern and activity profile varied with the
pH of the reaction mixture. The immobilized enzyme was further characterized for its biocatalytic activity with respect to
kinetic properties such as Km and Vmax and compared with free enzyme. Paramagnetic nanoparticle-immobilized enzyme showed
more affinity for substrate compared to free one. The nature of silica and nickel varied from amorphous to crystalline nature
and vice versa upon immobilization of enzyme. To the best of our knowledge, this is the first report of its kind for change
of nature from one form to other under normal temperatures upon diastase interaction with NSP. 相似文献
994.
Four nickel carbonate-bearing minerals from Australia have been investigated to study the effect of Ni for Mg substitution.
The spectra of nullaginite, zaratite, widgiemoolthalite and takovite show three main features in the range of 26,720–25,855 cm−1 (ν1-band), 15,230–14,740 cm−1 (ν2-band) and 9,200–9,145 cm−1 (ν3-band) which are characteristic of divalent nickel in six-fold coordination. The Crystal Field Stabilization Energy (CFSE)
of Ni2+ in the four carbonates is calculated from the observed 3A2g(3F) → 3T2g(3F) transition. CFSE is dependent on mineralogy, crystallinity and chemical composition (Al/Mg-content). The splitting of the
ν1- and ν3-bands and non-Gaussian shape of ν3-band in the minerals are the effects of Ni-site distortion from regular octahedral. The effect of structural cation substitutions
(Mg2+, Ni2+, Fe2+ and trivalent cations, Al3+, Fe3+) in the carbonate minerals is noticed on band shifts. Thus, electronic bands in the UV–Vis–NIR spectra and the overtones
and combination bands of OH and carbonate ion in NIR show shifts to higher wavenumbers, particularly for widgiemoolthalite
and takovite. 相似文献
995.
Biswas HS Datta J Chowdhury DP Reddy AV Ghosh UC Srivastava AK Ray NR 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17413-17418
Hydrogenated diamond-like carbon (HDLC) has an atomically smooth surface that can be deposited on high-surface area substrata and functionalized with reactive chemical groups, providing an ideal substrate for protein immobilization. A synthetic sequence is described involving deposition and hydrogenation of DLC followed by chemical functionalization. These functional groups are reacted with amines on proteins causing covalent immobilization on contact. Raman measurements confirm the presence of these surface functional groups, and Fourier transform infrared spectroscopy (FTIR) confirms covalent protein immobilization. Atomic force microscopy (AFM) of immobilized proteins is reproducible because proteins do not move as a result of interactions with the AFM probe-tip, thus providing an advantage over mica substrata typically used in AFM studies of protein. HDLC offers many of the same technical advantages as oxidized graphene but also allows for coating large surface areas of biomaterials relevant to the fabrication of medical/biosensor devices. 相似文献
996.
Ying‐Fang Ting Chihliang Chang Raju Jannapu Reddy Dr. Dhananjay R. Magar Kwunmin Chen Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(23):7030-7038
Practical and convenient synthetic routes have been developed for the synthesis of a new class of pyrrolidinyl–camphor derivatives ( 7 a–h ). These novel compounds were screened as catalysts for the direct Michael addition of symmetrical α,α‐disubstituted aldehydes to β‐nitroalkenes. When this asymmetric transformation was catalyzed by organocatalyst 7 f , the desired Michael adducts were obtained in high chemical yields, with high to excellent stereoselectivities (up to 98:2 diastereomeric ratio (d.r.) and 99 % enantiomeric excess (ee)). The scope of the catalytic system was expanded to encompass various aldehydes and ketones as the donor sources. The synthetic application was demonstrated by the synthesis of a tetrasubstituted‐cyclohexane derivative from (S)‐citronellal, with high stereoselectivity. 相似文献
997.
A. Sakunthala M. V. Reddy S. Selvasekarapandian B. V. R. Chowdari H. Nithya P. Chirstopher Selvin 《Journal of Solid State Electrochemistry》2010,14(10):1847-1854
The compound, lithium trivanadate (LiV3O8), was synthesized by the polymer precursor method, using the polymer polyvinylpyrrolidone. The electrochemical performance
of LiV3O8 was compared with LiV3O8 synthesized by the solid state reaction method. The prepared compounds were characterized by X-ray diffraction, scanning
electron microscopy, and high-resolution transmission electron microscopy techniques. The electrochemical performances were
studied by cyclic voltammetry and galvanostatic cycling in the voltage range of 2.0 to 4.0 V at room temperature (25 °C).
The compound prepared by the polymer precursor method was found to have a good cycling stability. A reversible capacity value
of 203 mAh/g (2.18 mol of Li) and 170 mAh/g (1.83 mol of Li) was obtained at the end of the 70th cycle, at a current density
of 30 and 120 mA/g, respectively. 相似文献
998.
P. Muralidhar Reddy Wan-Yu Hsu Jun-Fu Hu Yen-Peng Ho 《Journal of the American Society for Mass Spectrometry》2010,21(3):421-424
Microwave-assisted proteolytic digestion often yields misscleaved peptides, attributed to incomplete hydrolysis reactions
between enzymes and substrates. The number of missed cleavages is an important parameter in proteome database searching. This
study investigates how various factors affect digestion processes. Optimum conditions for microwave-assisted digestion (50
mM Tris buffer, 30 min at 60°C, and enzyme to protein molar ratio of 1:5) were determined. The digestion products obtained
from eight standard proteins were characterized based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS).
Experimental results indicate that the digestion temperature, reaction time, enzyme to substrate ratio, and digestion buffer
affect the number of misscleaved peptides and incomplete digestion percentages. Although all protein molecules in a sample
could be digested into peptides within a few minutes under microwave irradiation, longer reaction times or methods to maximize
the enzyme activity should be considered if digestion completeness is a major concern. 相似文献
999.
M. Penchal Reddy W. Madhuri N. Ramamanohar Reddy V.R.K. Murthy R. Ramakrishna Reddy 《Journal of magnetism and magnetic materials》2010,322(19):2819-2823
The low temperature microwave sintered NiCuZn and MgCuZn ferrites with compositions Ni0.35Cu0.05Zn0.60Fe2O4 and Mg0.35Cu0.05Zn0.60Fe2O4 were synthesized by conventional mixed oxide method. NiCuZn and MgCuZn ferrite samples obtained showed better sintered densities at 950 and 900 °C, respectively. The scanning electron micrographs of both the ferrite samples appear to be very much similar. The magnitude of initial permeability of MgCuZn ferrite samples is found to be obviously higher than those of NiCuZn ferrite samples at all sintering temperatures. This is mainly due to the fact that MgCuZn ferrite has smaller magnetocrystalline anisotropy constant and magnetostrictive constant. NiCuZn ferrites have higher saturation magnetization than MgCuZn ferrites, which is due to the higher magnetic moment of NiCuZn ferrites. Our results indicate that the microwave sintering method seems to be a potential technique in the MLCI technology. 相似文献
1000.
N. Y. Sreedhar P. Reddy Prasad M. Sankara Nayak D. Rekha C. Nageswara Reddy 《中国化学会会志》2009,56(6):1139-1146
In the present paper novel column solid phase extraction procedure was developed for the determination of Cd(II) and Pb(II) in cows', goats', ewes', buffalos' and humans' milk samples using newly synthesized reagent 2,2′‐DPED3P (2,2′‐{[1,2‐diphenylethane‐1,2‐diylidene]dinitrilo}diphenol) for preconcentration and separation prior to differential pulse polarography using amberlite XAD‐2 in the ranges of pH 4.0–5.0. The sorbed elements were subsequently eluted with 10 mL of 2 M HCl elutes were analysed by differential pulse polarography (DPP). The interference of foreign ions has also been studied. Effects of various instrumental parameters are investigated and received conditions are optimized. The total metal concentration of the milk samples in the study area were in the following ranges 0.030–0.090 μg L?1 of Cd(II), 0.009–0.026 μg L?1 of Pb(II) respectively. The limits of detections were found to be 0.020 and 0.024 μg L?1 for Cd(II) and Pb(II) respectively by applying a preconcentration factor ~40. The proposed enrichment method was applied successfully for the determination of metal ions in cows', goats', ewes', buffalos' and humans' milk samples. 相似文献