PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Pyrolysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources
PubMed1982

Acute toxicosis of budgerigars (Melopsittacus undulatus) caused by pyrolysis products from heated polytetrafluoroethylene: microscopic study.

An ultrastructural study was performed on the respiratory system of budgerigars (including 6 controls) which were acutely affected by inhalation of toxic fumes from heated polytetrafluoroethylene (PTFE pyrolysis products) or had survived fro 24 hours after a sublethal exposure. The controls were exposed to fumes from heated plan aluminum (ie, not coated with PTFE). The microanatomy of lungs of the controls was described and compared with that of lungs of the birds exposed to PTFE pyrolysates. The PTFE pyrolysates caused extensive, severe necrotizing and hemorrhagic pneumonitis. These lesions were associated with amorphous elongate conglomerates of particles which were similar to those isolated on membrane filters from fumes generated from heated PTFE--this supporting the hypothesis that the toxic principle in PTFE pyrolysates is at least, in part, related to generated particulates.

Acute Disease↗
PubMed1981

[Effect of heating on the benz(a)pyrene content in wood pyrolysis products].

Benz(a)pyrene was detected in the ether-insoluble fraction of acidic water on being heated to 100 and 300-450 degrees C, while heating of total acidic water and settled tar at 300-450 degrees C did not cause any changes in the content of this compound. The obtained results suggest that the ether-soluble fraction of acidic water contains compounds which promote benz(a)pyrene breakdown or inhibit its synthesis from products of timber pyrolysis.

Benzopyrenes↗
PubMed1994

Simultaneous measurement of cocaine, cocaethylene, their metabolites, and "crack" pyrolysis products by gas chromatography-mass spectrometry.

We developed a sensitive and specific assay for the simultaneous measurement of cocaine, cocaethylene, six of their metabolites, and anhydroecgonine methyl ester, a pyrolysis product, in biological fluids. The assay involves solid-phase extraction columns containing a copolymeric bonded phase for isolation of cocaine analytes, derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide and 10 g/L trimethylchlorosilane, and measurement with gas chromatography-mass spectrometry operating in the selected-ion monitoring mode. Detector responses for analytes were linear over a concentration range of 3.1-1000 micrograms/L. The limits of detection were approximately 1 microgram/L for cocaine, ecgonine methyl ester, and benzoylecgonine and 3-6 micrograms/L for the remaining analytes. Hydrolysis of cocaine and artifact formation of anhydroecogonine methyl ester during extraction and assay was < 1%. Cocaine and its derivatives appear in different proportions in plasma, saliva, and urine according to the biological fluid and time of measurement. Each biological fluid provides unique information on the disposition of cocaine in human subjects.

Administration, Intranasal↗
PubMed1993

[Studies on numerical taxonomy of Smilacaceae plants in Zhejiang Province by pyrolysis-high resolution gas chromatography].

The best taxonomic results were obtained in the analysis of rhizomes of 9 species and 1 variety of Smilacaceae plants grown in Zhejiang Province by using pyrolysis-high resolution gas chromatography and numerical taxonomy. When compared with the result of thin layer chromatography, it was found that those by classical taxonomy were basically reasonable, but Smilax china should be divided into two types: one with big berries and the other with small berries.

Chromatography, Gas↗
PubMedDate not supplied

Toxicological aspects of firesmoke: polymer pyrolysis and combustion.

Combustion toxicology is a complex field, and predicting the thermal breakdown products of natural and synthetic polymers is an inexact science. Practitioners of emergency medicine, occupational and environmental medicine, industrial hygiene, and toxicology must keep in mind a wide range of potential combustion and pyrolysis products when dealing with clinical and regulatory issues in fire safety.

Air Pollutants↗
PubMedDate not supplied

Toxic pyrolysis products of solvents, paints, and polymer films.

The organic chemicals used for solvents, paint, and polymer films are resistant to heat, but if the temperature is raised sufficiently, all will pyrolyze or degrade thermally to form new, lower-molecular-weight chemical species. The solvents include nonhalogenated and halogenated varieties, and their possible occupational exposures and reaction products are described. Paint and paint-like coatings, when pyrolyzed, always produce smoke, but toxic metals included as pigment may produce hazardous fumes. The condition "meat wrapper's asthma" is described to illustrate the effects once believed due to PVC pyrolysis.

Air Pollutants, Occupational↗
PubMed2004

Synthesis of scroll-type composite microtubes of Mo2C/MoCO by controlled pyrolysis of Mo(CO)6.

Composite microtubes of Mo(2)C/MoCO have been synthesized for the first time under well-controlled conditions by thermal decomposition of Mo(CO)(6) at about 600 degrees C. Here, thermal stability and phase transition of the products, as well as the influence of reaction temperature and argon flow rate, have been carefully investigated. All samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The reaction model and rolling mechanism were proposed on the basis of the experimental facts.

Journal Article↗
PubMed1988

Species and sex differences in genotoxicity of heterocyclic amine pyrolysis and cooking products in the hepatocyte primary culture/DNA repair test using rat, mouse, and hamster hepatocytes.

Eleven mutagenic heterocyclic amines, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]-indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3]indole (Trp-P-2), 2-amino-6-methyl-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1), 2-aminodipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), 2-amino-9H-pyrido[2,3-b]indole (A alpha C), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo [4,5-f]quinoline (MeIQX), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-diMeIQX), and 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-diMeIQX), were studied for genotoxicity in the hepatocyte/DNA repair test employing hepatocytes of male rats, male and female mice, and male hamsters. In these four assay systems, all compounds elicited DNA repair in at least three systems, except Trp-P-2, which was uniformly inactive. However, there were several significant differences in the responses of different systems. Rat and hamster hepatocytes responded to nine of the ten genotoxic compounds with the exception of Glu-P-2. Male and female mouse hepatocytes responded to Glu-P-2, whereas female, but not male, mouse hepatocytes responded to MeIQX and 4,8-diMeIQX. These results illustrate species and sex differences in response to these heterocyclic amines and suggest that a number of these compounds are carcinogenic in hamsters, as they have been in rats and mice.

Amines↗
PubMed1995

Pyrolysis-gas chromatography of carbonate apatites used for sintering.

Gas chromatography was employed to quasi-continuously determine the amount of carbon dioxide that evolved from carbonate apatite specimens during sintering. Assuming that the carbonate in the specimens decomposed to carbon dioxide on a mole-for-mole basis, the determination of the carbon dioxide evolved allowed for the determination of the amount of carbonate that remained in the specimens during different stages of sintering. Previously, this measurement could be carried out only after sintering was completed. Comparison of data obtained from specimens compacted isostatically at 600 MPa for sintering with powder specimens indicated that the amount of carbonate remaining in the sintered apatite mass strongly depended on heating rates, heating temperatures, and holding-time intervals.

Apatites↗
PubMed2003

Theoretical studies on the gas-phase pyrolysis of 2-phenoxycarboxylic acids: an ONIOM approach.

Various ONIOM combinations-ONIOM(HF/6-31G*: PM3), ONIOM(B3LYP/6-31G*: PM3), ONIOM(MP2/6-31G*: PM3), and ONIOM(MP2/6-31G*: HF/3-21G)--were applied to investigate thermal decomposition mechanisms of four 2-phenoxycarboxylic acids (2-phenoxyacetic acid, 2-phenoxypropionic acid, 2-phenoxybutyric acid, and 2-phenoxyisobutyric acid) in the gas phase. All the transition states and intermediates of the reaction paths were optimized. The reaction pathway of four reactants yielding the phenol, CO, and the corresponding carbonyl compound was characterized on the potential energy surface and found to proceed stepwise. The first step corresponds to the elimination of phenol and the formation of alpha-lactone intermediate through a five-membered ring transition state, and the second step is the cycloreversion process of alpha-lactone intermediate to form CO and the corresponding carbonyl compound. The reaction pathway of latter three compounds to produce the carboxylic acid and phenol via a four-membered cyclic transition structure was also examined theoretically. Comparison with experiment indicates that the activation parameters for the fist reaction channel are accurately predicted at the ONIOM(MP2/6-31G*: HF/3-21G) level of theory.

Journal Article↗