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61.
M. S. A. Rani N. S. Mohamed 《International Journal of Polymer Analysis and Characterization》2015,20(6):491-503
In the present work, an attempt has been made to prepare a new natural biopolymer blend electrolyte of carboxymethyl cellulose/chitosan impregnated with NH4NO3 by the solution casting technique. The conductivity for the system was measured by impedance spectroscopy. The incorporation of 40 wt.% NH4NO3 optimized the ambient temperature conductivity of the electrolyte up to 1.03 × 10?5 S cm?1. All electrolytes were found to follow the Arrhenius relationship. Dielectric studies confirmed that the electrolytes obey non-Debye behavior. The temperature dependence of the power law exponent s for the highest conducting film can be represented by the correlated barrier hopping model. 相似文献
62.
The present work describes an exciting method for the selective and sensitive determination of calcitonin in human blood serum samples. Adopting the surface molecular imprinting technique, a calcitonin-imprinted polymer was prepared on the surface of the zinc oxide nanostructure. Firstly, a biocompatible tyrosine derivative as a monomer was grafted onto the surface of zinc oxide nanostructure followed by their polymerization on vinyl functionalized electrode surface by activator regenerated by electron transfer–atom transfer radical polymerization (ARGET–ATRP) technique. Such sensor can predict the small change in the concentration of calcitonin in the human body and it may also consider to be as cost-effective, renewable, disposable, and reliable for clinical studies having no such cross-reactivity and matrix effect from real samples. The morphologies and properties of the proposed sensor were characterized by scanning electron microscopy, cyclic voltammetry, difference pulse voltammetry and chronocoulometry. The linear working range was found to be 9.99 ng L−1 to 7.919 mg L−1 and the detection limit as low as 3.09 ± 0.01 ng L−1 (standard deviation for three replicate measurements) (S/N = 3). 相似文献
63.
A series of 2-(arylimino)-3-(hydroxyimino)butanes 3a–g, easily accessed by the condensation of variously substituted anilines 1a–g with biacetyl monoxime 2, were efficiently cyclized to afford 2,3-dimethylquinoxaline-1-oxides 4a–g using bis(acetoxy)phenyl-λ 3-iodane as an oxidant. This methodology utilizes a commercially available and environmental benign oxidant to achieve the title compounds in excellent yields under mild conditions.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
64.
Various selenyl-substituted aryl aldehydes were obtained using dithiothreitol (DTT) as a reducing agent for diselenides in the presence of a base. For electron-deficient haloaryl aldehydes, a weak base, such as K2CO3, performed well. However, for electron-rich haloaryl aldehydes, a stronger base, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), was required for successful substitution. The selenyl-substitution of heteroaryl substrates were also investigated to obtain satisfactory yields of the desired products. 相似文献
65.
Nayana JosephJubi John Rani RajanSreeja Thulasi Anupa MohanE. Suresh K.V. Radhakrishnan 《Tetrahedron》2011,67(26):4905-4913
Functionalized indanones are readily prepared in good to excellent yields by the Pd/Rh catalyzed carboannulation of bicyclic and tricyclic hydrazines with 2-iodobenzonitrile, 2-cyanophenylboronic acid and 2-formylphenylboronic acid. The reaction with 2-formylphenylboronic acid afforded 3,4-disubstituted cyclopentenes as minor product along with indanones under Rh catalyzed conditions, whereas indanols were obtained as the major product under Pd catalyzed conditions. The products obtained can be synthetically manipulated easily to pharmaceutically important molecules. 相似文献
66.
In silico analysis of keratinase Ker P from Pseudomonas aeruginosa revealed that its full gene of 1,497 bp constituted of a 72-bp signal sequence along with a long 520 bp pro-sequence and 905 bp core region. Position specific multiple sequence alignment of Ker P protein with other distant proteases revealed high variability within their N-terminal regions while the core protein was considerably conserved. Ker P (F1) and its four N-terminal truncations (F2-F5) lacking 72, 177, 405, 507 bp, respectively, were cloned and constitutively expressed as extracellular protein in pEZZ-18 secretory vector with Escherichia coli HB101 as the expression host. Ker P F1, Ker P F2, Ker P F3 and Ker P F4 products were active whereas no keratinolytic activity was obtained in Ker P F5. Further analysis revealed that only 187 bp pro-sequence region is required for correct folding of the protein into its active conformation and, thus, has chaperone-like activity. Further, comparative biochemical characterization revealed that the full-length keratinase Ker P F1 was catalytically more efficient than the truncated forms. Among the truncated enzymes, keratinase Ker P F4 exhibited better thermostability than Ker P F2 with a t(1/2) of >1 h at 60 °C. It also had a higher V (max) and K (m) on casein as compared with Ker P F2. However, no significant variation was observed with respect to kinetics on synthetic substrates. 相似文献
67.
The propagation of plane harmonic waves are studied in a microstretch fluid medium. It is found that five basic waves can propagate at distinct speeds in an infinite linear homogeneous isotropic microstretch fluid. Out of these five waves, one is a longitudinal micro-rotational wave, two are coupled longitudinal waves and remaining two are coupled transverse waves. The longitudinal micro-rotational wave travels independently and is not influenced by the microstretching of the medium, while the coupled longitudinal waves arise due to the presence of microstretching and coupled transverse waves arise due to the presence of micro-rotation in the medium. Speed of propagation of all the waves are found to be complex valued and dispersive at low frequency, but almost non-dispersive at high frequency. Due to complex valued speeds of propagation, all the waves are attenuating but differently. Coupled sets of longitudinal waves reduce to a longitudinal wave of micropolar fluid in the absence of microstretching. Reflection phenomena of a set of coupled longitudinal waves incident obliquely at the free surface of a microstretch fluid half-space has been investigated. Closed formulae for the reflection coefficients are presented and computed numerically for a particular medium. The real and imaginary parts of the complex speeds of all the waves and their corresponding attenuation coefficients have also been studied numerically and depicted graphically against frequency parameter. 相似文献
68.
In this paper, a highly selective Sudan IV molecularly imprinted polymer was synthesized by surface molecular imprinting technique in combination with a sol?Cgel process using ??-aminopropyl triethoxysilane as functional monomer, tetraethoxysilane as cross-linker and activated silica gel as support material. The imprinted polymer was characterized by FT-IR spectra, scanning electron micrograph and adsorption experiments and it was exhibited good recognition and selective ability, offered a faster rate for the adsorption of Sudan IV. Using the imprinted material as sorbent, a solid-phase extraction coupled with high-performance liquid chromatography method for determination of trace Sudan IV was presented. The detection limit (S/N = 3) was 25.2 ng L?1, and the RSD for five replicate was 2.86%. With a loading flow rate of 2.5 mL min?1 for loading 30 mL, an enrichment factor of 104 was achieved. This method was applied for extraction and determination of chilli powder and duck egg samples with good recoveries ranging from 85.3 to 98.1%. 相似文献
69.
G. Chandra Sekhar Reddy A. Uma Ravi Sankar M. Veera Narayana Reddy C. Radha Rani C. Suresh Reddy 《Journal of heterocyclic chemistry》2011,48(6):1229-1233
A series of a new class of phosphorus analogue macrocycles was accomplished by condensation of N‐substituted‐[bis(3,5‐dimethyl‐2‐hydroxybenzyl)]‐amines with various phosphorus dichlorides in dry toluene in the presence of triethylamine at 0–50°C. All the title compounds were evaluated for antimicrobial activity to determine their efficacy and were effective in suppressing the growth of bacteria and fungi. The chemical structures of the title products were characterized by IR, 1H, 13C, 31P‐NMR, mass spectral studies, and elemental analysis. J. Heterocyclic Chem., (2011). 相似文献
70.
Yadav RA Rani P Kumar M Singh R Singh P Singh NP 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,84(1):6-21
IR and spectra of the L-ascorbic acid (L-AA) also known as vitamin C have been recorded in the region 4000-50 cm(-1). In order to make vibrational assignments of the observed IR and Raman bands computations were carried out by employing the RHF and DFT methods to calculate the molecular geometries and harmonic vibrational frequencies along with other related parameters for the neutral L-AA and its singly charged anionic (L-AA(-)) and cationic (L-AA(+)) species. Significant changes have been found for different characteristics of a number of vibrational modes. The four ν(O-H) modes of the L-AA molecule are found in the order ν(O(9)-H(10))>ν(O(19)-H(20))>ν(O(7)-H(8))>ν(O(14)-H(15)) which could be due to complexity of hydrogen bonding in the lactone ring and the side chain. The CO stretching wavenumber (ν(46)) decreases by 151 cm(-1) in going from the neutral to the anionic species whereas it increases by 151 cm(-1) in going from the anionic to the cationic species. The anionic radicals have less kinetic stabilities and high chemical reactivity as compared to the neutral molecule. It is found that the cationic radical of L-AA is kinetically least stable and chemically most reactive as compared to its neutral and anionic species. 相似文献