Renner–Teller induced photodissociation of HCO in the first absorption band: Determination of linewidths for the Ã 2A″ K=0,1 states by filter-diagonalization

2000 ◽  
Vol 113 (11) ◽  
pp. 4588-4597 ◽  
Author(s):  
Jan Weiß ◽  
Reinhard Schinke ◽  
Vladimir A. Mandelshtam
Keyword(s):  
Absorption Band ◽  
Filter Diagonalization

DC Polarographic and Spectrophotometric Determination of Ampicillin Capsules

1980 ◽  
Vol 63 (5) ◽  
pp. 1049-1051
Author(s):  
Juan A Squella ◽  
Luis J Nunez-Vergara ◽  
Maximo Aros
Keyword(s):  
Absorption Band ◽  
Spectrophotometric Determination ◽  
Degradation Product ◽  
Uv Absorption ◽  
Acidic Hydrolysis ◽  
Average Recovery ◽  
Polarographic Wave ◽  
Spectrophotometric Methods ◽  
Hydrolysis Of

Abstract Polarographic and spectrophotometric methods are proposed for the determination of ampicillin in capsules. Acidic hydrolysis of ampicillin with 1% HCHO in 0.3N HCl yields a degradation product identified as 2-hydroxy-3-phenyl-6-methylpyrazine. This compound has a well defined UV absorption band at 380 nm and a polarographic wave at –0.55 V vs SCE, which can be used for analytical purposes. Individual capsule assays, composite assays, and recovery studies are described. The average recovery values and standard deviations (SD) for UV and polarographic determinations were 99.20% (SD 0.95) and 100.85% (SD 1.09), respectively

Determination of hydroxyl concentrations in prepolymers from the infrared absorption band of tetrahydrofuran-associated hydroxyl groups

1982 ◽  
Vol 54 (2) ◽  
pp. 232-238 ◽  
Author(s):  
Chung Sul Youn. Kim ◽  
Allan L. Dodge ◽  
Suk Fai. Lau ◽  
Andrew. Kawasaki
Keyword(s):  
Absorption Band ◽  
Infrared Absorption ◽  
Hydroxyl Groups ◽  
Infrared Absorption Band

Recent Advances in the Chemistry of Covalently Bound Flavin Coenzymes

1972 ◽  
Vol 27 (9) ◽  
pp. 1069-1071 ◽  
Author(s):  
W. C. Kenney ◽  
W. H. Walker ◽  
E. B. Kearney ◽  
R. Seng ◽  
T. P. Singer ◽  
...  
Keyword(s):  
Amino Acid ◽  
Absorption Band ◽  
Performic Acid ◽  
Cysteic Acid ◽  
Hypsochromic Shift ◽  
Ninhydrin Reaction ◽  
Acid Environment ◽  
Definite Proof ◽  
Covalently Bound

Following elucidation of the structures of the flavin components of succinate dehydrogenase (SD) as N (3) -histidyl-8α-FAD and of monoamine oxidase (MAO) as cysteinyl-8α-FAD and determination of the peptide sequences around the flavin sites of these enzymes, attention has been focused on the covalently bound FAD of Chromatium cytochrome c-552. As documented in preliminary communications, the FAD moiety of this enzyme is also substituted at the 8α-position, as judged from ESR hyderfine structure of the free radical cation and the characteristic hypsochromic shift of the second absorption band of the neutral flavoquinone in purified preparations of the flavin. Definite proof has come from the liberation of 8-carbxyriboflavin on performic acid treatment of the enzyme. In regard to ESR and optical spectra and the tendency of the purified flavin (liberated by proteolysis) to undergo autooxidation with a further hypsochromic shift of the second absorption band and increased fluorescence, the flavin resembles the MAO flavin. The fact that fluorescence is >90% quenched at all pH values even at the FMN level and doees not vary with pH between 3.2 and 8 also suggests a thioether linkage as in cysteinyl riboflavin. In many respects, however, the Chromatium flavin differs from cysteinyl riboflavin. Highly purified preparations from tryptic-chymotryptic digests give a positive chloroplatinic test. Electrophoresis clearly shows the presence of carboxyl and amino groups but the peptide gives no characteristic ninhydrin reaction and amino acid analysis of performic acid oxidized samples yields cysteic acid and threonine in amounts less than equimolar to the flavin. The amino acid environment around the flavin may account for these results although a linkage other than a thioether remains a possibility.

Determination of the atmospheric-water-vapor content in the 940-nm absorption band by use of moderate spectral-resolution measurements of direct solar irradiance

1998 ◽  
Vol 37 (21) ◽  
pp. 4678 ◽  
Author(s):  
Victoria E. Cachorro ◽  
Pilar Utrillas ◽  
Ricardo Vergaz ◽  
Plinio Durán ◽  
Angel M. de Frutos ◽  
...  
Keyword(s):  
Water Vapor ◽  
Absorption Band ◽  
Spectral Resolution ◽  
Solar Irradiance ◽  
Water Vapor Content ◽  
Atmospheric Water Vapor ◽  
Atmospheric Water

Synthesis and Characterizations of Metal Oxide-Sulfonic Acid Functionalized ZSM-5 for Photocatalytic Degradation and Adsorption of Dimethylarsenic Acid

2014 ◽  
Vol 699 ◽  
pp. 994-999 ◽  
Author(s):  
Alias Mohd Yusof ◽  
Nur Nadira Sulaiman ◽  
Hadi Nur
Keyword(s):  
Electron Microscopy ◽  
Absorption Band ◽  
Ultra Violet ◽  
Arsenic Species ◽  
Zinc Nitrate ◽  
X Ray Diffraction ◽  
Alkyl Groups ◽  
Transmission Electron ◽  
Stretching Vibration

TiO2 and ZnO were incorporated into ZSM-5 using titanium tetrachloride and zinc nitrate as the precursors respectively. The functional group of ZSM-5 was further modified using mercaptopropyl trimethoxysilane (MPTS). This method was used to produce a two-in-one composite namely TiO2-ZSM5-SH and ZnO-ZSM5-SH which holds the abilities to degrade organic pollutants as well as to remove them from the environment. Determination of the composition and morphology of all synthesized catalyst complexes were characterized using Fourier Transformed Infrared (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HR-TEM). Results obtained indicated that the average diameters for TiO2-ZSM5-SH particles are 2.398 μm, slightly larger than the diameter of ZnO-ZSM5-SH particles with an average of 1.8067 μm. Both TiO2-ZSM5-SH and ZnO-ZSM5-SH appeared as sphere-like shape and amorphous since both metal oxides were incorporated into the ZSM-5 pores. The compositions of these complexes were proven by the presence of a strong silica absorption band showing the existence of Si-O stretching vibrations and SiO2 asymmetric vibrations in the synthesized complexes. For TiO2-ZSM5-SH, the Ti-O stretching vibration can be seen at 3467.29 cm-1 and at 1637.86 cm-1 while Zn-O absorption band appeared at 455.52 cm-1 in ZnO-ZSM5-SH. The symmetric and asymmetric vibrations of –CH2 and –CH3 indicate the existence of alkyl groups in the ZSM-5. The ability of catalyst complexes synthesized as photocatalyst were applied and tested on the photodegradation of dimethylarsenic acid (DMA) under ultra violet (UV) radiation which showed that these catalyst complexes are proven be able to degrade DMA into less toxic intermediates and are able to adsorb the remaining arsenic species from the aqueous solutions.

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