Summary (text)
Abstract (text)
Evaluation of emission characteristics and compliance of emission standards for in-use petrol driven vehicles in Delhi.
The tail pipe CO (carbon monoxide) and HC (hydrocarbon) emission characteristics of in-use petrol driven vehicles were evaluated between November 1996 through September 1997 in Delhi. A total of 4300 vehicles were checked at CRRI Pollution Checking Centre. Approximately 90% of the total vehicles meet the prescribed CO emission standards even without following routine I/M practices. The age of the vehicles appeared to have influence on the emission characteristics. The non-compliance level was found to be higher for older vehicles. Insignificant correlation was observed between CO and HC emissions for all categories of in-use petrol driven vehicles. The emission reduction (gain) in CO and HC emissions was observed for two wheelers equipped with four-stroke engines and four wheelers fitted with catalytic converters over their respective conventional vehicles. The observed high compliance levels indicate that existing tail pipe emission standards are lenient and need to be reviewed. The emission standards are proposed for different categories of in-use petrol driven vehicles.
[Pubmed - MEDLINE]
Full Text Sources
检索记录[]
丁香园旗下网站Summary (text)
Abstract (text)
Vibrational characterization of simple peptides using cryogenic infrared photodissociation of H2-tagged, mass-selected ions.
We present infrared photodissociation spectra of two protonated peptides that are cooled in a ~10 K quadrupole ion trap and &tagged& with weakly bound H(2) molecules. Spectra are recorded over the range of 600-4300 cm(-1) using a table-top laser source, and are shown to result from one-photon absorption events. This arrangement is demonstrated to recover sharp (&D& ~6 cm(-1)) transitions throughout the fingerprint region, despite the very high density of vibrational states in this energy range. The fundamentals associated with all of the signature N-H and C=O stretching bands are completely resolved. To address the site-specificity of the C=O stretches near 1800 cm(-1), we incorporated one (13)C into the tripeptide. The labeling affects only one line in the complex spectrum, indicating that each C=O oscillator contributes a single distinct band, effectively &reporting& its local chemical environment. For both peptides, analysis of the resulting band patterns indicates that only one isomeric form is generated upon cooling the ions initially at room temperature into the H(2) tagging regime.
[Pubmed - MEDLINE]
Full Text Sources
检索记录[]
丁香园旗下网站Summary (text)
Abstract (text)
Efficient biliary excretion of susalimod, probably via the bromosulphthalein carrier, studied in a chronic bile fistula model in dogs.
Susalimod is a structural analogue of sulphasalazine, known to be extensively excreted in the bile in various animal species and for inducing bile duct hyperplasia after long-term treatment of the dog with doses exceeding 25 mg kg(-1). In this study local concentrations of susalimod in the bile duct were determined after oral administration in dogs. A chronic bile fistula experimental model was designed to affect the bile duct as little as possible. The dogs received repeated oral doses of 25-150 mg kg(-1) day(-1) for 5 these doses had been used in previous toxicology studies. Extremely high biliary concentrations of unchanged susalimod (20,000-43,000 microM) were measured. Biliary excretion approached saturation at the higher doses, resulting in super-proportional increases in peripheral plasma concentrations as the dose was increased. The maximal bile/plasma concentration ratio was 4300. The high biliary clearance was indicative of almost complete first-pass elimination at doses below saturation of the elimination process. Interaction studies with the biliary excretion marker bromosulphthalein (BSP) demonstrated that susalimod and BSP probably share the same carrier transport system in biliary excretion. The elimination of BSP from plasma was prolonged 20 times and the biliary excretion rate was markedly reduced when susalimod was co-administered with BSP. These results show that susalimod is highly enriched in the bile, in a saturable manner, after oral administration. The compound interacts with the biliary excretion of BSP, suggesting that it shares the same carrier-mediated transport system.
[Pubmed - MEDLINE]
Full Text Sources
检索记录[]
丁香园旗下网站Summary (text)
Abstract (text)
Effects of mutations in aspartate 14 on the spectroscopic properties of the [Fe3S4]+,0 clusters in Pyrococcus furiosus ferredoxin.
The properties of [Fe(3)S(4)](+,0) clusters in wild-type and mutant forms of Pf Fd with Asp, Ser, Cys, Val, His, Asn, and Tyr residues occupying position 14, i.e., proximal to the three micro(2)-S atoms of the cluster, have been investigated by the combination of EPR, variable-temperature magnetic circular dichroism (VTMCD), and resonance Raman (RR) spectroscopies. Two distinct types of [Fe(3)S(4)] clusters are identified on the basis of the breadth of the S = (1)/(2) [Fe(3)S(4)](+) EPR resonances and the marked differences in the VTMCD spectra of the S = 2 [Fe(3)S(4)](0) clusters. On the basis of the available NMR data for [Fe(3)S(4)](+, 0) clusters in ferredoxins, the distinctive properties of these two types of [Fe(3)S(4)] clusters are interpreted in terms of different locations of the more strongly coupled pair of irons in the oxidized clusters and the valence-delocalized pair in the reduced clusters. Near-IR VTMCD measurements indicate the presence of S = (9)/(2) valence-delocalized pairs in both types of [Fe(3)S(4)](0) clusters, and the spin-dependent delocalization energies associated with the Fe-Fe interactions were determined to be approximately 4300 cm(-)(1) in both cases. We conclude that the nature of the residue at position 14 in Pyrococcus furiosus ferredoxin is an important determinant of the location of the reducible pair of irons in a [Fe(3)S(4)](+,0) cluster, and the redox properties of the wild-type and mutant ferredoxins are discussed in light of these new results.
[Pubmed - MEDLINE]
Full Text Sources
检索记录[]
丁香园旗下网站}