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71.
In this paper, we present a fourth order method for computing multiple roots of nonlinear equations. The method is based on Jarratt scheme for simple roots [P. Jarratt, Some efficient fourth order multipoint methods for solving equations, BIT 9 (1969) 119-124]. The method is optimal, since it requires three evaluations per step, namely one evaluation of function and two evaluations of first derivative. The efficacy is tested on a number of relevant numerical problems. It is observed that the present scheme is competitive with other similar robust methods. 相似文献
72.
Cross-linked 4-vinylpyridine-styrene beads (PVPS) containing various amounts of pyridine rings were synthesized and reaction with methyliodide and peroxyacetic acid gave corresponding N-methylpyridinium salts and N-oxides with more than 92% of the pyridine rings being transformed. PVPS formed stable complexes with bromine and chlorine in the ratio 1:1, and when a higher amount of halogen was used, complexes with two molecules of halogen on each pyridine were formed. Similar complexes were also formed with PVPS-N-oxides in the presence of bromine and chlorine, while the reaction of PVPS-hydrohalide with bromine and chlorine resulted in hydrobromide perbromide and hydrochloride perchloride resins. The chemical activity of halo-substituted resins was tested in the reaction with 1,1-diphenylethylene. Chi or o-substituted resins are very stable, while bromo-substituted beads gave bromoalkene, dibromide, and alkoxybromide, depending on the structure of the reagent, solvent, and reaction temperature. 相似文献
73.
Structural,optical, electrical and luminescence properties of electron beam evaporated CdSe:In films
M. G. Syed Ahamed Basheer K. S. Rajni V. S. Vidhya V. Swaminathan A. Thayumanavan K. R. Murali M. Jayachandran 《Crystal Research and Technology》2011,46(3):261-266
CdSe:In films were prepared by electron beam evaporation technique using CdSe and In2Se3 (purity ∼99.9%) pellets. The crystal structure of the films with and without Indium, measured by X‐ray diffraction (XRD), showed a typical wurtzite structure, higher Indium doping shifts the peak angle to higher side along with the broadening of the peaks. X‐ray photoelectron spectroscopy (XPS) studies indicated binding energies corresponding to 54 eV (Se3d5/2), 444 eV (In 3d5/2), 411 eV (Cd 3d3/2), (Cd 3d5/2). Atomic force microscope (AFM) studies indicated a uniform surface.The grain size decreases with increase of In doping. A decrease in the band gap was observed with increase of dopant concentration. Resistivity of the films is in the range of 10‐3 Ωcm. Carrier density was in the range of 1021 cm‐3 for the films. The photolumineasenec spectra (PL) spectra indicated three peaks. The peak intensity decreases as the Indium concentration increases. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
74.
Bismuth silicate glasses containing lithium oxide with composition 20Li2O·(80 − x)Bi2O3·xSiO2 (5 ? x ? 70 mol%) have been prepared by melt-quench technique. Density (D), molar volume (VM) and glass transition temperature (Tg) for all the glass samples have been measured. FTIR spectroscopy has been employed to investigate the structure of these glasses in order to obtain information about the competitive role of Bi2O3 and SiO2 in the formation of glass network. The increase of SiO2 content in the glass matrix results in increasing the Si-O-Si bond angle and hence the ionicity of Si-O bond increases with decrease in Bi2O3/SiO2 ratio. The optical transmittance spectra of all the glasses have been recorded in the wavelength range 200-3300 nm. The values of optical band gap (Eg) have been determined from the cutoff wavelength of these glasses. The average electronic polarizability of oxide ion () and the optical basicity (Λth) have been estimated from the calculated values of the Eg and were found to be dependent directly on Bi2O3/SiO2 ratio. The variation in different physical parameters such as D, VM and Tg and optical parameters; viz., Eg, , Λth with Bi2O3/SiO2 ratio have been analyzed and discussed in terms of change in the glass structure. 相似文献
75.
Analytical study for investigating the behaviour of Nd-doped Glass, YAG and GGG under the heat capacity mode of operation 总被引:1,自引:0,他引:1
In this paper, detailed analytical studies on heat capacity operation in Nd-doped glass, YAG and GGG has been reported. The effect of the rising temperature on gain and hence on the output energy/power has been numerically worked out. The studies predicted that several kilowatts of the useful output power can be extracted out from the laser materials under investigation when operated under the heat capacity mode. The studies also revealed that output power levels can be scaled up by increasing the number of disks and by increasing the disk aperture size. The factors limiting the power enhancement are also discussed. The estimated results are in good agreement with the other reported experimental results. 相似文献
76.
7-Hydroxy-8-methoxy-3-(3,4-methylenedioxyphenyl)-4H-1-benzopyran-4-one (1), a new isoflavone reported to occur in the aerial parts and roots of Tephrosia maxima has been synthesized by the oxidative rearrangement of 2′-hydroxy-3′-methoxy-4′-benzyloxy-3,4-methylenedioxychalcone (4) with thallium (III) nitrate (TTN) in trimethyl orthoformate (TMOF), followed by acid catalysed cyclization and debenzylation. It has also been synthesized by another method from 2,3,4-trihydroxy-3,4′-methylenedioxydeoxybenzoin; the hitherto unknown biisoflavone, 7,7′-dimethoxy-3′,4″,3″,4″-dimethylenedioxy-8,8′-biisoflavonyl ether was also formed during this method. 相似文献
77.
Naiem Ahmad Wani Vivek Kumar Gupta Rajni Kant Subrayashastry Aravinda Rajkishor Rai 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(10):1170-1172
2‐{1‐[(Pyrazin‐2‐ylformamido)methyl]cyclohexyl}acetic acid (Pyr‐Gpn‐OH), C14H19N3O3, is an N‐protected derivative of gabapentin (Gpn). The compound crystallizes in the triclinic space group P and the molecular conformation is stabilized by intramolecular five‐ (C5) and seven‐membered (C7) hydrogen‐bonded rings. The packing of the molecules reveals intermolecular O—H...O and C—H...N hydrogen bonds, together with π–π interactions. 相似文献
78.
The paper deals with the exploitation of Ipomoea carnea as a feedstock for the production of bioethanol. Dilute acid pretreatment under optimum conditions (3 %H2SO4, 120 °C for 45 min) produced 17.68 g L?1 sugars along with 1.02 g L?1 phenolics and 1.13 g L?1 furans. A combination of overliming and activated charcoal adsorption facilitated the removal of 91.9 % furans and 94.7 % phenolics from acid hydrolysate. The pretreated biomass was further treated with a mixture of sodium sulphite and sodium chlorite and, a maximum lignin removal of 81.6 % was achieved. The enzymatic saccharification of delignified biomass resulted in 79.4 % saccharification with a corresponding sugar yield of 753.21 mg g?1. Equal volume of enzymatic hydrolysate and acid hydrolysate were mixed and used for fermentation with a hybrid yeast strain RPRT90. Fermentation of mixed detoxified hydrolysate at 30 °C for 28 h produced ethanol with a yield of 0.461 g g?1. A comparable ethanol yield (0.414 g g?1) was achieved using a mixture of enzymatic hydrolysate and undetoxified acid hydrolysate. Thus, I. carnea biomass has been demonstrated to be a potential feedstock for bioethanol production, and the use of hybrid yeast may pave the way to produce bioethanol from this biomass. 相似文献
79.
Samir A. Patel Milan V. Patel Arabinda Ray Rajni M. Patel 《Journal of polymer science. Part A, Polymer chemistry》2003,41(15):2335-2344
Low molecular weight poly(ether ketone)s were synthesized from phenol, 1,4‐phenylenedioxy diacetylchloride, chloroacetylchloride, and dichloroalkanes [1,2‐dichloroethane and dichloromethane] by a Friedel–Crafts reaction with anhydrous aluminum chloride as a catalyst and carbon disulfide as a solvent. The conditions for the preparation of the poly(ether ketone)s and the chlorine contents obtained with the Carius method were examined, and a reaction scheme for each resin was established. The molecular weights and polydispersities of the resins were obtained by gel permeation chromatography. The polyketones were characterized by IR spectroscopy. The characteristic frequencies due to different functional groups were assigned. The thermal properties of the resins were studied with thermogravimetry and differential scanning calorimetry. The characteristic temperatures of thermal degradation for the poly(ether ketone)s were evaluated with thermogravimetric analysis. The kinetic parameters for the decomposition reactions of the resins were obtained with Broido and Doyle's method, and the heats of fusion were obtained from differential scanning calorimetry thermograms. The polyketones were thermally stable up to 200 °C. All the polyketones were tested for their microbial properties against bacteria, fungi, and yeast. The effect of poly(ether ketone)s on the growth of these microorganisms was investigated, and the polyketones were found to inhibit the growth of the microorganisms to a considerable extent. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2335–2344, 2003 相似文献
80.
A new lignan rhamnoside identified as 2,6-di(4’,5’-dihydroxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-1-hydroxy-5-O-rhamnopyranoside (1) has been isolated from the ethanolic extract of seed pods of Bauhinia retusa.Its structure was established by extensive spectroscopic techniques(UV,IR,1D NMR,2D NMR,HRESIMS). 相似文献