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21.
Proton and deuteron magnetic relaxation rates of the four solutes acetone, acetonitrile, trimethylamine, and tetramethylurea in their aqueous mixtures are reported. For the normal and deuterated organic substances the water was D2O and H2O, respectively. The intermolecular relaxation rates were determined. Experimental results for the self-diffusion coefficients of trimethylamine and tetramethylurea in their aqueous mixtures are also reported. From these results and literature data the A parameter, A=(1/T1)inter·D1/c′1 being a criterion for association, was calculated. We obtained the result that only for the largest solute molecule, i.e. tetramethylurea, A showed the typical concentration dependence indicating solute-solute association. For the other three components self-association is not outside the range of the sensitivity of the present method. 相似文献
22.
S. F. Patil S. A. Bhoite A. G. Bedekar 《Journal of Radioanalytical and Nuclear Chemistry》1985,93(3):133-140
The studies of radiation decomposition of ammonium nitrate in the presence of MnO2, PbO and V2O5 with the absorbed dose reveal that MnO2 retards while PbO and V2O5 accelerate the rate of radiolysis. G/NO
2
–
/ values were found to increase with the mole% of V2O5 in an admixture. The results are explained on the basis of electron donor-acceptor properties of oxides affecting the equilibrium concentration of electrons present in pure ammonium nitrate in the presence of the added oxides. 相似文献
23.
The cyclization of 2-(1-alkynyl)-2-alken-1-ones 1 proceeded very smoothly in the presence of alcohols 2 with a catalytic amount of Cu(I)Br in DMF at 80 degrees C, leading to the formation of highly substituted furans 3. The catalytic system reported herein is easy to handle, compared to the previously known system wherein the reaction between 1 and 2 needed to use moisture sensitive gold(III) chloride. 相似文献
24.
Murthy MB Daya Sagar BS Patil RL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(6):1277-1280
The electronic absorption spectra of eight substituted acetic acids have been measured at room temperature in several solvents. The ground state dipole moments are evaluated experimentally for these molecules. These ground state values are used in conjunction with the spectral results to evaluate their first electronically excited state dipole moments. For all the molecules investigated here the dipole moments in the excited state are higher than their ground state values. 相似文献
25.
Summary A new method for the spectrophotometric determination of bismuth, cobalt and nickel after extraction of their xanthates into molten naphthalene is described. The optimum pH values are 2.4–4.5 for Bi, 7.5–9.0 for Co, 5.5–7.5 for Ni. The naphthalene containing the metal chelates is dissolved in chloroform, and the absorbance is measured against a reagent blank at 362, 350 and 420 nm for Bi, Co and Ni and respectively. Few ions interfere and the method has been applied successfully for the determination of these metal ions in various complex materials.
Zusammenfassung Eine neue Methode für die spektrophotometrische Bestimmung von Wismuth, Kobalt und Nickel nach Extraktion ihrer Xanthate mit geschmolzenem Naphthalin wurde beschrieben. Das optimale pH für Wismut beträgt 2,4–4,5, für Kobalt 7,5–9,0 und für Nickel 5,5–7,5. Das die Metallchelate enthaltende Naphthalin wird in Chloroform gelöst und die Extinktion gegen eine Reagens-Leerlösung bei 362, 350 bzw. 420 nm für Bi, Co bzw. Ni gemessen. Nur wenige Ionen stören. Das Verfahren wurde mit Erfolg zur Bestimmung der genannten Ionen in verschiedenen komplexen Gemischen angewandt.相似文献
26.
Patra S Sarkar B Ghumaan S Patil MP Mobin SM Sunoj RB Kaim W Lahiri GK 《Dalton transactions (Cambridge, England : 2003)》2005,(7):1188-1194
The isomeric title complexes were obtained in almost equimolar ratio from the reaction of Ru(trpy)Cl3 and L. Crystal structure analyses of the perchlorate hemihydrates, electrochemical and spectroscopic (NMR, UV/VIS, EPR) studies, supported by DFT calculations, reveal distinct differences between the isomeric redox series [1]n+(tetrazine-Nt trans to Cl) and [2]n+(pyrazolyl-Np trans to Cl; n= 0, 1, 2). The latter system with the pi acceptors trpy and tetrazine in the equatorial plane and the pyrazolyl and chloride donors in the axial positions exhibits facilitated oxidation, lower energy MLCT transitions, more balanced chelate coordination, and a higher g anisotropy in the oxidised (RuIII) state. According to partially resolved EPR spectra of one-electron reduced neutral compounds and they have the unpaired electron predominantly in the tetrazine ring of L. 相似文献
27.
Spiro [3H-indole-3,2′-[4H] pyrido [3,2-e]-1,3-thiazine]-2,4′ (1H) diones, a class of previously unknown compound which does not form under conventional conditions, can be prepared by treatment of ‘in situ’ generated 3-indolylimine derivatives with 2-mercaptonicotinic acid under microwave irradiation in absence of any solvent or solid support in 85-92% yields in 3-8 min. The facile one pot reaction is generalized for a variety of ketones and amines to give pure pyrido [3,2-e] thiazine derivatives, which do not require further purification processes. 相似文献
28.
Kuiry SC Megen E Patil SD Deshpande SA Seal S 《The journal of physical chemistry. B》2005,109(9):3868-3872
This article reports an easy chemical method of synthesizing boehmite nanofibers by a modified sol-gel process involving aluminum isopropoxide precursor. Nanorods of gamma-alumina have been successfully prepared after dehydration of the viscous sol at 600 degrees C for 4 h in air. The boehmite nanofibers and gamma-alumina nanorods were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy for surface chemistry and functional groups, scanning electron microscopy, high-resolution transmission electron microscopy with selected area electron diffraction, and energy-dispersed spectroscopy for morphology and structure identification. The length of the boehmite nanofibers was found to be more than 10 mum with a crystalline lattice structure. The mechanism of formation of the boehmite nanofibers included the preferential growth along the longitudinal axis due to interaction between the solvent molecules and the surface OH- groups of hydrogen bonds. It is also suggested that the boehmite nanofibers may have formed due to the inherent instability of the planar structure of the boehmite lattice. The diameter of the gamma-alumina nanorods was found to be less than 10 nm with a varying length in the range of 50-200 nm. Boehmite to gamma-Al2O3 transformation was attributed to the loss of water molecules by internal condensation of protons and hydroxyl ions. 相似文献
29.
Numerical Algorithms - A parabolic convection-diffusion-reaction problem is discretized by the non-symmetric interior penalty Galerkin (NIPG) method in space and discontinuous Galerkin (DG) method... 相似文献
30.
S. S. Suryavanshi U. R. Ghodake A. M. Sankpal S. V. Kakatkar R. S. Patil S. R. Sawant 《Czechoslovak Journal of Physics》1995,45(6):509-516
For the ferrites Ni
x
Cd1–x
Fe2O4 (x=0.3, 0.4,1) the lattice parameter, grain size, electrical resistivity, initial permeability, Curie temperature and squareness of the magnetization curve were measured. The results are discussed in terms of the model of the canted spin structure taking into account the domain structure of the polycrystalline ferrite. 相似文献