摘要:

The infrared and Raman spectra of dimethyldithiophosphinate anion (CH3)2PS2were measured and the vibrational modes for the anion complex were assigned. A Normal Coordinate Analysis in the Modified General Valence Force Field (MGVFF) approximation was carried out assuming C2vsymmetry. Ab Initio Calculations at RHF and MP2 level were also carried out for the anion geometry as well as for its frequencies, intensities and force constants.

ISSN:0038-7010    

DOI:10.1080/00387019808001653

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

With comparable molar quantities, chromotropic acid reacts with compounds containing aldehyde groups -CHO e.g. with formadehyde or glyoxylic acid to form cyclic compounds with rings containing four chromotropic acid fragments — cyclotetrachromotropylene derivatives. The cyclic compounds, due to the presence of a cavity in the molecule, can play the part of host and complex smaller molecules, which has been confirmed on the basis of triethylamine by the1H-NMR measurements. Using spectrophotometric method the stability constant of 1:1 complex formed between Ti(IV) and cyclic compound chromotropic acid with formaldehyde has been determined - K = (9,0 ± 0,1) 104.

ISSN:0038-7010    

DOI:10.1080/00387019808001654

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The oxidation of Cu(II)/tetraglycine complex in borate buffer (pH=9.2) in aqueous medium, by dissolved oxygen is strongly accelerated by S(IV). The reaction is adequate for S(IV) determination as the concentration of (Cu(H-3G4)]−formed is proportional to SO32- concentration. The [Cu(H-3G4)]−presents a maximum absorbance at 365 nm (ε = 7400 mol−1.L.cm−1) and it was followed spectrophotometrically by flow injection analysis procedure. The detection limit was 7×10−6mol.L−1and the linear regression showed a standard deviation of 0.02% (n=5). Kinetics studies showed the catalytic effect of some transition metal ions, “which can be present in environmental samples, in the oxidation of S(IV). The pseudo-first-order rate constants were determined in the presence of formaldehyde.

ISSN:0038-7010    

DOI:10.1080/00387019808001655

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Simulated annealing algorithm (SAA) was applied to locate the global minimum of a non-linear least square function for spectra fitting. The resolution of methylene region of two13C-NMR spectra of polystyrene was implemented successfully with this method. Compared with the existing methods, this technique has important advantages in two respects: one is that the resulting resolution of spectra with this method have lesser dependence on the initial values of the parameters inputted to start the optimization of the least square function; the other is that it provides the possibility to determine the peaks which cannot be recognized by the observation. With this technique, some possible error arising from the observation can be avoided.

ISSN:0038-7010    

DOI:10.1080/00387019808001656

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The stability of the doped state of conductive polythiophenes under air was investigated by the use of Infrared (IR) and UV-visible (UV) spectroscopies. Poly(3-methyl thiophene) doped with BF3-ethyl ether (BFEE). shows higher stability due to its stereoregularity-chain structure. While the doped polythiophene (PT) degrades easily under the moisture.

ISSN:0038-7010    

DOI:10.1080/00387019808001657

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper, the study on the effect of cAMP on erythrocyte membrane proteins by FTIR, deconvolution and curvefitting was reported. It was found that cAMP affects the secondary structure of membrane proteins by changing random and β-turn regions to the α-helix segments. The regulation of cAMP has a best concentration region, during which cAMP has the strongest regulating function. Meanwhile, cGMP and ATP has a negative effect on membrane proteins' secondary structure comparing to cAMP.

ISSN:0038-7010    

DOI:10.1080/00387019808001658

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper describes the method of a phase-alternating composite π pulse sequences, in which the subroutines are programed instead of the previously reported “IMSL” library DUNSJ to solve the non-linear least square problems, being used to minimize the pulse angles with respect to resonance off-set. The main program and subroutines were carried out on a personal computer. It is found that the results from the new program were in agreement with that reported in the reference being obtained from IBM/3600 computer and the present method is more effeciant than other existing pulse sequences.

ISSN:0038-7010    

DOI:10.1080/00387019808001659

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The uv-vis spectra of eight ortho-hydroxy- andpara-hydroxy schiff bases were recorded in different solvents. Inductive and resonance effect of the substituents affect the electronic spectra of those molecules, while, intra-molecular hydrogen bond formation or breakage have little effect on the uv-visible spectra.

ISSN:0038-7010    

DOI:10.1080/00387019808001660

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Magnetic resonance (MR) response obtained in a strongly heterogeneous magnetic field with a linear gradient is analysed. It is shown that the employment of strong magnetic field gradients enables the MR spectroscopy to be accomplished in a system with selectively populated energy states (SSMRS). The method can be applied for measuring such physical quantities as the spin diffusion coefficient, D, spin-lattice, T1mand spin-spin, T2m, relaxation times and mobility, pm, of paramagnetic elements in individual Zeeman energy states.

ISSN:0038-7010    

DOI:10.1080/00387019808001661

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A fiber optic probe was interfaced to a photon counting system for the determination of nicotinamide adenine dinucleotide reduced [NAD(P)H] by a bioluminescence method. The reagents employed in a bacterial luciferase/flavin mononucleotide /decanal system were optimized. Attempts were made to increase the quantum yield of the system. Dodecanal, tridecanal, and tetradecanal were evaluated as alternative aldehyde reagents for decanal, and hydrogen peroxide was added to the system. Neither attempt increased the quantum yield of the system. However, a relatively low detection limit of 1.6 × 10−9M for NAD(P)H was obtained with a linear dynamic range of 3.8 orders of magnitude. These results demonstrate the sensitivity of this instrumentation and assay.

ISSN:0038-7010    

DOI:10.1080/00387019808001662

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor