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291.
In view of the known advantages of the microwave promoted reactions done in dry medium, the seed gum sourced from Cassia marginata has been graft copolymerized with acrylonitrile in dry medium at neutral alumina support under microwave irradiation. Grafting conditions were optimized and the representative graft copolymer was characterized by Fourier transform‐infrared, Thermo gravimetric analysis, Scanning electron microscopy, and X‐Ray Diffraction (XRD) measurement, taking Cassia marginata gum (CM) as reference. Much higher % grafting and % efficiency could be obtained in the microwave promoted alumina supported grafting as compared to grafting done in aqueous medium (microwave promoted and conventional). Properties of the microwave synthesized Cassia marginata gum‐graft‐poly(acrylonitrile) (CM‐g‐PAN) were studied and compared with the parent seed gum. © 2007 John Wiley & Sons, Ltd. 相似文献
292.
K. Prasad Lily K. Kumari K.P. Chandra K.L. Yadav S. Sen 《Applied Physics A: Materials Science & Processing》2007,88(2):377-383
Polycrystalline (Na0.5Sb0.5)TiO3 was prepared using a high-temperature solid-state reaction method. An XRD analysis indicated the formation of a single-phase
monoclinic structure. Complex impedance studies revealed the presence of grain boundary effects from 300 °C onwards. Also,
the dielectric relaxation in the system was found to be of a non-Debye type. The ac conductivity data were used to evaluate
the density of states at the Fermi level, the minimum hopping length and activation energy of the compound. The dc electrical
and thermal conductivities of grain and grain boundary have been assessed. The correlated barrier hopping model was found
to successfully explain the mechanism of charge transport in (Na0.5Sb0.5)TiO3.
PACS 72.20.Ee; 77.22.Ch; 77.22.Gm; 77.84.Dy; 81.05.Je 相似文献
293.
A comparative biochemical study of four Group IV element compounds with specific sulphur-containing organic substrates has been carried out and discussed. The structural characterizations of these organometallics, viz. Me2SiLCl, Me2SiL2, Me3SiL, Ph2SiLCl, Ph2SiL2, Ph3SiL, Ph3GeL, Cp2TiLCl, Cp2TiL2, Cp2ZrLCl and Cp2ZrL2 (where LH?2-acetylthiophene thiosemicarbazone) had been deduced on the basis of various physico-chemical and instrumental techniques, viz., IR, UV, 1H NMR, 13C NMR AND 29SI NMR spectral studies. All the organometallics and the parent thiomine have been screened against a number of microbes and their sterilizing power in male mice tested. The results of these biocidal studies show that the organosilicon(IV) and organogermanium(IV) compounds are more active than the organotitanium(IV) and organozirconium(IV) derivatives. An attempt has also been made to correlate the structural aspects of the molecule with its biological activity. 相似文献
294.
Umadevi M Kumari MV Bharathi MS Vanelle P Terme T 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):122-127
Synthesis, spectroscopic and thermal studies of some complexes of a new N(2)-Schiff base ligand of N(1),N(2)-bis((E)-2-methyl-3-phenylallylidene)ethane-1,2-diamine (L) with a general formula of MLX(2) (M = Zn(II), Cd(II) and Hg(II); X = Cl(-), Br(-), I(-), SCN(-) and N(3)(-)) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-vis spectra, FT-IR spectra, MS, (1)H NMR and (13)C NMR spectra. The conductivity measurement as well as spectral data indicated that the complexes are non-electrolyte. (1)H and (13)C NMR spectra have been studied in DMSO-d(6) and/or CDCl(3). The thermal behavior of the complexes shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. Activation thermodynamic parameters of decomposition such as E*, ΔH*, ΔS* and ΔG* were calculated from TG curves. 相似文献
295.
Lobana TS Kumari P Sharma R Castineiras A Butcher RJ Akitsu T Aritake Y 《Dalton transactions (Cambridge, England : 2003)》2011,40(13):3219-3228
The influence of substituents at the C(2) carbon of N(1)-substituted thiosemicarbazones, {C(4)H(3)X-C(2)(CH(3))=N(3)-N(2)H-C(1)(=S)N(1)HR(2)} (X = O, S) on the geometry of nickel(ii) complexes has been investigated. The presence of a methyl group at the C(2) position of 2-acetylfuran-N(1)-substituted thiosemicarbazones {(C(4)H(3)O)-C(2)(CH(3))=N(3)-N(2)H-C(1)(=S)N(1)HR(2), R(2) = CH(3), HaftscN-Me; C(2)H(5), HaftscN-Et; C(6)H(5), HaftscN-Ph} induces unusual coordination by the furan ring and yielded high spin octahedral nickel(II) complexes, [Ni(κ(3)-O, N(3), S-aftscN-R(2))(2)], CH(3)1, C(2)H(5)2, and 2[Ni((κ(3)-O, N(3), S-aftscN-Ph)(2)] 3 (μ(eff) = 2.98, 1; 2.96, 2; 2.92, 3). With 2-acetylthiophene-N(1)-substituted thiosemicarbazones, {(C(4)H(3)S)-C(2)(CH(3))=N(3)-N(2)H-C(1)(=S)N(1)HR(2), R(2) = CH(3), HattscN-Me; C(2)H(5), HattscN-Et; C(6)H(5), HattscN-Ph}, N(3), S chelated low spin trans square planar complexes, {[Ni(κ(3)-O, N(3), S-attscN-R(2))(2)], R(2) = CH(3), 4; C(2)H(5), 5; C(6)H(5), 6} with pendant thiophene rings have been obtained. The bigger sized sulfur atoms of the thiophene rings form short intramolecular contacts with the deprotonated hydrazinic nitrogen atoms (SN(2)) inhibiting its lability for possible coordination to nickel(II). Complexes have one independent molecule (1) or two independent molecules (2, 3) in their respective crystal lattices. The simultaneous presence of methyl groups at the C(2) and N(1) atoms of 2-acetylthiophene-N(1)-methylthiosemicarbazone (HattscN-Me) have facilitated the binding of triphenylphosphine in three-coordinate copper(i) halide complexes, [CuX(η(1)-S-HattscN-Me)(Ph(3)P)] (X, Br, 7; Cl, 8), which represent an unusual donor set of ligands, namely, triphenylphosphine, sulfur of a thio-ligand and a halide. 相似文献
296.
Joshi R Poonam Saini R Guleria S Babu GD Kumari M Gulati A 《Natural product communications》2011,6(8):1155-1158
Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. simultaneous distillation extraction (SDE), supercritical fluid extraction (SFE), analyzed by GC and GC/MS and compared with headspace analysis (HS). The composition of the volatile components extracted by the three methods differed considerably. In SFE, phenylethanol (14.7%), linalool (7.9%), (E)-linalool oxide furanoid (3.5%), epoxy linalool (1.6%), geraniol (2.3%) and hotrienol (1.5%) were major components. m-Xylene (2.6%), (E)-linalool oxide pyranoid (5.4%), p-myrcene (5.2%), alpha-cadinol (4.3%) and methyl palmitate (2.9%) were major compounds isolated by SDE. 3-hexenol (2.1%) (E)-4,8-dimethyl-1,3,7-nonatriene (20.9%) and linalool (35.1%) are major components in headspace analysis. Acetophenone and pheromone germacrene D is detected in tea flowers by all the methods studied. Floral, fresh and fruity odour of tea flowers is retained by SFE as there is very little loss of heat sensitive volatiles in SFE. The flavour isolated from SFE has superior quality compared to SDE. 相似文献
297.
Primitive polynomials,singer cycles and word-oriented linear feedback shift registers 总被引:1,自引:0,他引:1
Sudhir?R.?GhorpadeEmail author Sartaj?Ul?Hasan Meena?Kumari 《Designs, Codes and Cryptography》2011,58(2):123-134
Using the structure of Singer cycles in general linear groups, we prove that a conjecture of Zeng et al. (Word-Oriented Feedback
Shift Register: σ-LFSR, 2007) holds in the affirmative in a special case, and outline a plausible approach to prove it in the general case.
This conjecture is about the number of primitive σ-LFSRs of a given order over a finite field, and it generalizes a known formula for the number of primitive LFSRs, which,
in turn, is the number of primitive polynomials of a given degree over a finite field. Moreover, this conjecture is intimately
related to an open question of Niederreiter (Finite Fields Appl 1:3–30, 1995) on the enumeration of splitting subspaces of
a given dimension. 相似文献
298.
Li X Cheng J Lin K Saadat E Bolbos RI Jobke B Ries MD Horvai A Link TM Majumdar S 《Magnetic resonance imaging》2011,29(3):324-334
Purpose
A direct correlation between T1ρ, T2 and quantified proteoglycan and collagen contents in human osteoarthritic cartilage has yet to be documented. We aimed to investigate the orientation effect on T1ρ and T2 values in human osteoarthritic cartilage and to quantify the correlation between T1ρ, T2 vs. biochemical composition and histology in human osteoarthritic cartilage.Materials and methods
Thirty-three cartilage specimens were collected from patients who underwent total knee arthroplasty due to severe osteoarthritis and scanned with a 3T MR scanner for T1ρ and T2 quantification. Nine specimens were scanned at three different orientations with respect to the B0: 0°, 90° and 54.7°. Core punches were taken after MRI. Collagen and proteoglycan contents were quantified using biochemical assays. Histology sections were graded using Mankin scores. The correlation between imaging parameters, biochemical contents and histological scores were studied.Results
Both mean T1ρ and T2 at 54.7° were significantly higher than those measured at 90° and 0°, with T1ρ showing less increase compared to T2. R1ρ (1/T1ρ) values had a significant but moderate correlation with proteoglycan contents (R=.45, P=.002), while R2 (1/T2) was not correlated with proteoglycan. No significant correlation was found between relaxation times (T1ρ or T2) and collagen contents. The T1ρ values of specimen sections with high Mankin scores were significantly higher than those with low Mankin scores (P<.05).Conclusions
Quantitative MRI has a great potential to provide noninvasive imaging biomarkers for cartilage degeneration in osteoarthritis. 相似文献299.
The steady mixed convection flow and heat transfer from an exponentially stretching vertical surface in a quiescent Maxwell fluid in the presence of magnetic field, viscous dissipation and Joule heating have been studied. The stretching velocity, surface temperature and magnetic field are assumed to have specific exponential function forms for the existence of the local similarity solution. The coupled nonlinear ordinary differential equations governing the local similarity flow and heat transfer have been solved numerically by Chebyshev finite difference method. The influence of the buoyancy parameter, viscous dissipation, relaxation parameter of Maxwell fluid, magnetic field and Prandtl number on the flow and heat transfer has been considered in detail. The Nusselt number increases significantly with the Prandtl number, but the skin friction coefficient decreases. The Nusselt number slightly decreases with increasing viscous dissipation parameter, but the skin friction coefficient slightly increases. Maxwell fluid reduces both skin friction coefficient and Nusselt number, whereas buoyancy force enhances them. 相似文献
300.
Kumari Varsha Singh Tanupriya Devi Saroj Tandon Hiteshi Labarca Martín Chakraborty Tanmoy 《Journal of mathematical chemistry》2022,60(2):360-372
Journal of Mathematical Chemistry - Electronegativity (χ) is an important property of any chemical species as it helps to predict the pattern of physico-chemical interactions. In the present... 相似文献