Search results for "Benzene"
showing 10 items of 1701 documents
Development of a versatile, easy and rapid atmospheric monitor for benzene, toluene, ethylbenzene and xylenes determination in air
2009
Abstract A new procedure for the passive sampling in air of benzene, toluene, ethylbenzene and xylene isomers (BTEX) is proposed. A low-density polyethylene layflat tube filled with a mixture of solid phases provided a high versatility tool for the sampling of volatile compounds from air. Several solid phases were assayed in order to increase the BTEX absorption in the sampler and a mixture of florisil and activated carbon provided the best results. Direct head-space-gas chromatography–mass spectrometry (HS-GC–MS) measurement of the whole deployed sampler was employed for a fast determination of BTEX. Absorption isotherms were used to develop simple mathematical models for the estimation of…
Effects of cyclooxygenase-1/cyclooxygenase-2 inhibition on leukocyte/endothelial cell interactions in the rat mesentery.
2002
Nonsteroidal anti-inflammatory drugs (NSAID) inhibit cyclooxygenase activity and cause gastrointestinal damage in part by promoting leukocyte accumulation in the mucosa. Our aim was to evaluate the effects of selective blockade of the isoenzymes cyclooxygenase-1 and cyclooxygenase-2 on leukocyte adhesion in vivo. Leukocyte/endothelial cell interactions were examined in rat mesenteric venules before and after treatment with indomethacin, SC-560 (5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethylpyrazole, cyclooxygenase-1 inhibitor), DFP (5,5-dimethyl-3-(2-propoxy)-4-(4-methanesulfonyl)-2(5H)-furanone, cyclooxygenase-2 inhibitor), or SC-560 plus DFP (20 mg/kg, i.v. each). Indomethacin i…
Effect of polybrominated biphenyls on bromobenzene lethality in mice.
1977
Polybrominated biphenyls (PBBs) are inducers of hepatic microsomal cytochrome P450 and P1 450 in rats and mice. The purpose of this study was to determine, in mice, the effect of PBBs on the lethality of the hepatotoxin bromobenzene. Female NMRI mice were administered a single ip injection of 150 mg/kg PBBs and other mice received phenobarbital (PB), 100 mg/kg daily for 3 days, or 3‐methylcholanthrene (MC), 20 mg/kg daily for 3 days. At 24 hr after PB or MC and 24, 48, and 96 hr after PBBs animals received 3,150 mg/kg bromobenzene ip (LD85) and the time to death was recorded. Both PB and MC enhanced bromobenzene lethality and decreased the median time to death (LT50) from 23 hr in controls …
Uptake of chlorohydrocarbons from soil by lipid-containing semipermeable membrane devices (SPMDs)
1998
Chlorohydrocarbons (CHCs) were surveyed in contaminated lake shore soil in Central Finland with polyethylene membranes containing synthetic triolein (SPMDs). High levels of hexachlorobenzene (HCBz) and PCBs were found in a significant number of the SPMDs exposed 28 days to 35 soil sampling locations along the 350 meter long shoreline. Distributions of HCBz and PCBs were different as demonstrated by two maximas of HCBz and four maximas of PCBs observed. Soil was also analyzed at selected locations for concentrations of CHCs, organic carbon (OC) and moisture. Steady state environmental fate modeling and simple equilibrium partition estimates based on analytical results both gave the same stea…
Oxidative stress induces distinct physiological responses in the two Trebouxia phycobionts of the lichen Ramalina farinacea
2010
† Background and Aims Most lichens form associations with Trebouxia phycobionts and some of them simultaneously include genetically different algal lineages. In other symbiotic systems involving algae (e.g. reef corals), the relative abundances of different endosymbiotic algal clades may change over time. This process seems to provide a mechanism allowing the organism to respond to environmental stress. A similar mechanism may operate in lichens with more than one algal lineage, likewise protecting them against environmental stresses. Here, the physiological responses to oxidative stress of two distinct Trebouxia phycobionts (provisionally named TR1 and TR9) that coexist within the lichen R…
The organic air pollutant cumene hydroperoxide interferes with NOantioxidant role in rehydrating lichen
2013
Organic pollutants effects on lichens have not been addressed. Rehydration is critical for lichens, a burst of free radicals involving NO occurs. Repeated dehydrations with organic pollutants could increase oxidative damage. Our aim is to learn the effects of cumene hydroperoxide (CP) during lichen rehydration using Ramalina farinacea (L.) Ach., its photobiont Trebouxia spp. and Asterochloris erici. Confocal imaging shows intracellular ROS and NO production within myco and phycobionts, being the chloroplast the main source of free radicals. CP increases ROS, NO and lipid peroxidation and reduces chlorophyll autofluorescence, although photosynthesis remains unaffected. Concomitant NO inhibit…
CCDC 919328: Experimental Crystal Structure Determination
2013
Related Article: Kamran T. Mahmudov, Maximilian N. Kopylovich, Matti Haukka, Gunay S. Mahmudova, Espandi F. Esmaeila, Famil M. Chyragov, Armando J.L. Pombeiro|2013|J.Mol.Struct.|1048|108|doi:10.1016/j.molstruc.2013.05.041
The different kinetic and mechanistic behaviors of molybdenum and tungsten in the reduction of tris(benzene-1,2-dithiolato)Mo(VI) and W(VI) complexes…
2011
The mono-electronic reduction of tris(benzene-1,2-dithiolato)Mo(VI) and W(VI) complexes (ML3: M = Mo, W; L = S2C6H2−4, S2C6H3CH2−3) to their anionic forms ML−3 by L(+)-ascorbic acid (H2A) has been studied in tetrahydrofurane (THF):water and THF:methanol by means of diode-array, stopped-flow, and mass spectrometry–electrospray ionization (MS-ESI) spectroscopy. The kinetic study in methanol demonstrates that the reaction is first order in each reactant, the electron transfer being rate limiting. This fact was assessed by the absence of a primary saline effect and by the correlation observed between the activation free enthalpy (ΔG≠) and the reduction potentials measured by cyclic voltamperome…
An Efficient Synthesis of Rubin’s Aldehyde and its Precursor 1,3,5-Tribromo-2,4,6-tris(dichloromethyl)benzene
2011
2,4,6-Tribromobenzene-1,3,5-tricarboxaldehyde (4) can be efficiently prepared in two reaction steps from 1,3,5-tribromobenzene. The intermediate 1,3,5-tribromo-2,4,6-tris(dichloromethyl)benzene (3) crystallizes from petroleum ether in its C3h structure. However, in CDCl3 solution it exists at room temperature in two isomeric forms: 3a (C3h) and 3b (Cs) (1:1.15).The intramolecular Br・・・Cldistances are much smaller than the sum of the van der Waals radii. Therefore, the exocyclic C-C bonds show a hindered rotation.
Dodecyloxy-substituted 2,4,6-tris(styryl)pyridines
2008
(E,E,E)-2,4,6-Tris(styryl)pyridines 2a-c with 3, 6 or 9 dodecyloxy substituents were prepared by the highly stereoselective condensation reaction of collidine (8) and the corresponding phenyl-(1-phenyl-methylidene)amines 7a-c (Siegrist reaction). In contrast to the corresponding compounds with a benzene or a 1,3,5-triazine core, 2a-c do not show any hints for the formation of thermotropic liquid crystals. The major application of such star-shaped systems is in the field of nonlinear optics.