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 55 records · Page 3Linked to original sources
PubMed1989

A pyrolysis mass spectrometry study of fusobacteria.

Strains of fusobacteria (143) were examined by pyrolysis mass spectrometry (Py-MS) with a Horizon Instruments PYMS 200X. Fusobacterium necrogenes, F. necrophorum, F. nucleatum, F. mortiferum, F. varium, F. gonidiaformans, F. naviforme, F. russii and Leptotrichia buccalis were discriminated. Strains of fusobacteria isolated from tropical ulcers, although similar to F. mortiferum in conventional tests, were discriminated from each of these species in Py-MS. Identification of 416 spectra to species level agreed with conventional bacteriological methods in 91.8% of cases, was equivocal in 3.4% and disagreed in 4.8%. Classification based on pyrolysis data resolved groups largely corresponding to the recognised species. However, F. nucleatum strains were divided between two distinct groups. The tropical ulcer strains were resolved as a distinct homogeneous group. Py-MS is a rapid, inexpensive and convenient procedure for characterisation of bacteria, with the capacity for a high throughput of samples, although the initial cost of the apparatus is high.

Fusobacterium↗
PubMed1988

Reproducibility of pyrolysis mass spectrometry: effect of growth medium and instrument stability on the differentiation of selected Bacillus species.

The discrimination of a set of 53 strains, taken from four closely related Bacillus species (Bacillus subtilis, B. pumilus, B. licheniformis and B. amyloliquefaciens), was examined using pyrolysis mass spectrometry. Strains were grown on six different media to examine the effect of media variation, especially batch-to-batch variation of a single medium, on the pyrolysis mass spectra and strain discrimination achieved. Long-term reproducibility over a period of 14 months was also examined. It was shown that batch-to-batch media variation is insufficient to affect spectra and strain discrimination significantly, but different media types do affect this. It was shown that species groups could still be recovered from the data, however, with an appropriate data-handling system. It was not possible to directly compare spectra produced 14 months apart, but the strain and species discrimination achieved using each data-set were highly comparable.

Bacillus↗
PubMed1988

Presence of carcinogenic glutamic-acid pyrolysis products in human cataractous lens.

The carcinogenic glutamic-acid pyrolysis products, 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1) and 2-amino-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), were found to be present in human cataractous lenses, but not in normal bovine lenses. Contents of Glu-P-1 and Glu-P-2 in 35 human cataractous lenses were 832 and 20 ng, respectively. These results indicate that the human cataractous lens is exposed to the fluorescent compounds, carcinogenic glutamic pyrolysis products.

Aged↗
PubMed1991

Urinary excretion levels of carcinogenic glutamic acid pyrolysis products and their N-acetyl derivatives in humans.

UNLABELLED: The carcinogenic glutamic acid pyrolysis products 2-amino-6-methyldipyrido [1, 2-a: 3', 2'-d]imidazole (Glu-P-1) and 2-amino-dipyrido [1, 2-a: 3', 2'-d] imidazole (Glu-P-2), and their N-acetyl derivatives were measured in 24-h urine of individual subjects by high-performance liquid chromatography. These compounds were detected in all urine samples analyzed, although the contents varied widely among subjects. The mean levels of Glu-P-1, N-acetyl-Glu-P-1, Glu-P-2 and N-acetyl-Glu-P-2 in 24-h urine were 0.53, 0.41, 2.12 and 4.60 pmol, respectively. In vitro experiments revealed N-acetyltransferase activity with Glu-P-1 and Glu-P-2 in the cytosolic fractions from rat kidneys and human autopsy kidney specimens as well as those from liver specimens, suggesting that extrahepatic tissues may also play significant roles in the N-acetylation of these carcinogens. These results show that Glu-P-1 and Glu-P-2, after being partially N-acetylated in metabolic organs such as liver and kidney, are excreted into urine together with their N-acetyl derivatives. It is suggested that daily excretion of carcinogenic glutamic acid pyrolysis products and their N-acetyl derivatives into urine can be a suitable biological monitor for exposure to these carcinogens. ABBREVIATIONS: Glu-P-1, 2-amino-6-methyldipyrido [1, 2-a: 3', 2'-d] imidazole; Glu-P-2, 2-aminodipyrido [1, 2-a: 3', 2'-d] imidazole; N-acetyl-Glu-P-1, 2-acetylamino-6-methyldipyrido [1, 2-a: 3', 2'-d] imidazole; N-acetyl-Glu-P-2, 2-acetylaminodipyrido[1,2- a:3', 2'-d]imidazole; HPLC, high-performance liquid chromatography.

Acetylation↗
PubMed1975

Experimental toxicology of pyrolysis and combustion hazards.

Data are presented on the acute toxicity (mortality only) of the thermal degradation products of polymers obtained by two methods of degradation. One system utilized a slowly increasing temperature (5 degrees C/min) and gradual degradation of the polymer with the rats being exposed to degradation products as they were evolved. In this system the more toxic polymers included wool, polypropylene, poly(vinyl chloride), and urethane foam. The second system utilized conditions of rapid combustion and exposure of rats to the total products of combustion for a period of 4 hr. In this system the more toxic materials included red oak, cotton, acrylonitrile-butadiene-styrene (ABS), and styrene-acrylonitrile. It is of interest to note that the natural product wool is among the least toxic under these rapid combustion conditions and among the most toxic under slow pyrolysis conditions. Other materials also vary in the comparative toxicity of their thermal degradation products, depending upon the conditions of degradation and animal exposure. The two experimental techniques presented here may well represent the two extreme conditions of rapid combustion versus slow pyrolysis. Intermediate types of fire situations might be expected to result in relative acute toxicities somewhere between these two extremes. This report deals with acute toxicity on the basis of mortality data only and does not include other parameters of toxicity such as organ weights and histopathology.

Animals↗
PubMed1985

Pyrolysis products of PCBs.

Model compound studies which were previously done for impurities and environmental residues of chlorophenols and for wastes of chlorination processes were extended to the impurities and pyrolysis products of polychlorinated biphenyls (PCBs). Model compounds were commercial products or synthesized and their structures proven by spectroscopic methods. These models were used as analytical reference substances in GC/ECD and GC/MS studies of the pyrolyzed PCB samples. In addition to previously known neutral components like polychlorinated dibenzofurans (PCDFs), chlorophenolic substances, especially polychlorophenols (PCPs) and polychlorinated biphenylols (PCB-OHs) were observed as major pyrolysis products of PCBs. Capacitor fires are suggested to produce in many cases chlorophenols which are major toxic hazards to people.

Chromatography, Gas↗
PubMed1987

Organic emissions from coal pyrolysis: mutagenic effects.

Four different types of coal have been pyrolyzed in a laminar flow, drop tube furnace in order to establish a relationship between polycyclic aromatic compound (PAC) evolution and mutagenicity. Temperatures of 900K to 1700K and particle residence times up to 0.3 sec were chosen to best simulate conditions of rapid rate pyrolysis in pulverized (44-53 microns) coal combustion. The specific mutagenic activity (i.e., the activity per unit sample weight) of extracts from particulates and volatiles captured on XAD-2 resin varied with coal type according to the order: subbituminous greater than high volatile bituminous greater than lignite greater than anthracite. Total mutagenic activity (the activity per gram of coal pyrolyzed), however, varied with coal type according to the order: high volatile bituminous much greater than subbituminous = lignite much greater than anthracite, due primarily to high organic yield during high volatile bituminous coal pyrolysis. Specific mutagenic activity peaked in a temperature range of 1300K to 1500K and generally appeared at higher temperatures and longer residence times than peak PAC production.

Coal↗
PubMed1988

Carcinogenic tryptophan pyrolysis products potent inhibitors of type A monoamine oxidase and the platelet response to 5-hydroxytryptamine.

The effects of carcinogenic heterocyclic amines and beta-carbolines on 5-hydroxytryptamine-induced human platelet aggregation, on the uptake of 5-hydroxytryptamine by platelets, and on human monoamine oxidase activity were investigated. Of the dietary carcinogens and beta-carbolines studied, carcinogenic tryptophan pyrolysis products had greater pharmacological activities than other heterocyclic amines. The carcinogenic tryptophan pyrolysis products, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 3-amino-1-methyl-5H-pyrido[4,3-b]indole, which have been identified in the dialysis fluid of uraemic patients, were the most potent inhibitors of the aggregation response to 5-hydroxytryptamine, with IC50 (the concentrations causing 50% inhibition) values of 10 mumol/l and 50 mumol/l, respectively. 3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 3-amino-1-methyl-5H-pyrido[4,3-b]indole by themselves did not induce platelet aggregation, although these dietary carcinogens structurally resemble 5-hydroxytryptamine. Kinetic analyses showed that 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 3-amino-1-methyl-5H-pyrido[4,3-b]indole were potent competitive inhibitors of 5-hydroxytryptamine uptake by platelets with Ki 18 mumol/l and 42 mumol/l, respectively. Furthermore, carcinogenic tryptophan pyrolysates as well as beta-carbolines were found to be competitive selective inhibitors of monoamine oxidase 'type A'.

Blood Platelets↗
PubMed1991

Carcinogenic tryptophan pyrolysis products in the environment.

The purpose of this study is to evaluate the risk of carcinogenic tryptophan pyrolysis products to human health. During the last decade, a new series of heterocyclic amines has been isolated as potent mutagens and later shown to be potent carcinogens in experimental animals. Among them, 3-amino-1, 4-dimethyl-5H-pyrido [4, 3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido [4, 3-b]indole (Trp-P-2), carcinogenic tryptophan pyrolysis products, have been investigated from various points of view and useful pieces of information about them have been collected. These carcinogens are widely distributed in the environment such as airborne particles, rain water, cigarette smoke and cooked foods, and they possess various pharmacotoxicological activities such as convulsant activities and potent inhibitory effects on platelet function and dopamine metabolism. Recent investigations revealed that these compounds are present in human samples such as plasma, urine and bile, indicating that humans are actually exposed to these compound. It is a matter of urgency to establish a suitable method for monitoring the exposure levels of these compounds to humans.

Animals↗
PubMed1990

[Identification of 10 kinds of Zanthoxylum by pyrolysis GC].

In this paper, pyrolysis GC was applied to differentiate and fingerprint 10 kinds of Zanthoxylum on an OV-101 capillary column. Analytical conditions with this column, operating temperature, pyrolysis time and peak identifications are discussed.

Chromatography, Gas↗
PubMed1987

Abuse of smoking methamphetamine mixed with tobacco: I. Inhalation efficiency and pyrolysis products of methamphetamine.

Experiments of smoking methamphetamine in tobacco have been investigated. Inhalation efficiencies of methamphetamine into tar were 6 to 17% according to the additive amounts, suction volume, and intervals of smoking. Major pyrolysis products of methamphetamine in tar were identified as methamphetamine, amphetamine, phenylacetone, dimethylamphetamine, N-formyl-, N-acetyl-, N-propionyl-, and N-cyanomethyl-methamphetamine by the spectral analysis of infrared spectra (IR), mass spectra (MS), and proton magnetic resonance spectra (PMR), and comparison with the samples synthesized from authentic samples by one step. The largest pyrolysis product was N-cyanomethylmethamphetamine which is a new compound and easily metabolized to methamphetamine in the body. Methamphetamine itself transferred into tar was not so large, but the total active compounds in tar which would be metabolized to methamphetamine in the body were considerably larger.

Administration, Inhalation↗
PubMed1979

Pyrolysis analysis of the herbicide paraquat on cannabis by coupled gas chromatography-infrared spectroscopy.

Pyrolysis gas chromatography coupled with infrared identification of eluted peaks confirms that paraquat is pyrolyzed into chloromethane and 4,4'-dipyridyl at smoking temperatures and above. This reaction occurs at 610 degrees C to completion in small amounts in an inert atmosphere. The toxicity of 4,4'-dipyridyl remains to be determined. Pyrolysis of contaminated marijuana also produces the same two products, although detection at low limits is difficult with this procedure.

2,2'-Dipyridyl↗
PubMed1978

[Differentiation of structural viral proteins using pyrolysis gas chromatography].

Types 1, 2, and 5 of structural proteins of adenovirus as well as human albumin, pepsin, trypsin, and ribonuclease tend to exhibit characteristic substance patterns when exposed to pyrolysis-gas chromatography. Those patterns may be helpful in differentiating between those proteins. The presence of a distributional pattern is assumed to depend, in most cases, not only on the given amino acid composition, but also on the amino acid sequence of the protein proper. Samples of complex composition, such as complete viruses or allantois fluids, were much less suitable for differentiation by means of pyrolysis-gas chromatography.

Adenoviridae↗
PubMed1976

Ultrastructural alterations of rat lung exposed to pyrolysis products of polytetrafluoroethylene (PTFE, Teflon).

Ultrastructural changes of the lung tissues were evaluated in rats exposed to the pyrolysis products of Teflon at 380 degrees C., 400 degrees C;, and 450 degrees C., respectively, for 4 hours. At 450 degrees C. Teflon evolved numerous tiny particles (0.02 to 0.04 mum.), which were considered to be the toxic material, and at 550 degrees C., in addition to the tiny particles, large spherical particles (0.7 to 5.0 mum) were found. No particles were observed in the pyrolysis product produced at temperatures between 380 degrees C. and 425 degrees C. There were no clinical symptoms or lung alterations induced at temperatures below 425 degrees C colloidal carbon injected as a marker of increased vascular permeability did not pass through the alveolar capillary endothelium. At 450 degrees C. (approximate lethal temperature) rats revealed severe respiratory difficulty, pulmonary edema, hemorrhage, and necrosis of the tracheobronchial epithelium. The membranous pneumocytes appear to be vulnerable to the Teflon fume causing cytoplasmic swelling, bleb formation, fragmentation, and denudation. Similar changes were found in the endothelial cells, but to a much lesser extent. When Teflon fume generated at 450 degrees CnWAS FILTERED THROUGH A Millipore filter (pore size 0.2 mum.), rats revealed only slight degenerative changes in the superficial tracheobronchial epithelium, but no clinical signs.

Animals↗
PubMed2026

Enhanced Performance in All-Inorganic AgBiS2 Photodetectors via Oxygen-Inhibited Spray Pyrolysis Deposition.

AgBiS2 has emerged as a promising optoelectronic material due to its broad spectral response and strong light absorption. However, the current use of high-boiling solvents and organic buffers restricts fundamental studies and further performance optimization of AgBiS2's intrinsic properties. In this study, we develop an organic buffer-free AgBiS2 photodetector prepared using a low-temperature ultrasonic spray pyrolysis technique. Our theoretical analysis revealed that oxygen doping alters the optoelectronic characteristics by enhancing the density of states near the Fermi level, leading to consequent severe nonradiative charge carrier recombination. By incorporating excess thiourea while maintaining optimal substrate temperature for enhanced crystallinity, we successfully suppress oxygen defects and consequently improve photodetection performance. The optimized device exhibits a high responsivity of 0.046 A W-1 at 1050 nm, a low noise level (<8.5 &#xd7; 10-19 A2 Hz-1), and a fast response time (0.07 &#x3bc;s rise, 0.60 &#x3bc;s decay). Benefiting from the rapid response, the photodetector delivers high-resolution imaging with sharp edge definition. This work eliminates the interference of organic buffer layers to directly reveal how oxygen defect modulation affects the intrinsic optoelectronic properties of AgBiS2, offering a scalable pathway for high-performance, solution-processed photodetectors.

near-infrared detector↗
PubMed1978

The identification of ibuprofen and analogues in urine by pyrolysis gas chromatography mass spectrometry.

The pyrolysis gas chromatography mass spectrometry of Ibuprofen, Fenoprofen, Naproxen and Ketoprofen, a series of anti-inflammatory propionic acid derivatives, is shown to proceed via decarboxylation and elimination to yield characteristic ethyl and vinyl fragments. The pyrogram enables the identification of the drug to be achieved as the pure compound, in a formulated dosage form or excreted in urine. The presence of metabolites derived from Ibuprofen causes four new fragments to be observed in the urine pyrogram. The identification of 16 components of the control urine pyrogram is presented.

Anti-Inflammatory Agents↗
PubMed1987

Identification and quantification of arsenocholine and acetylarsenocholine in trace amounts in biological material by use of pyrolysis gas chromatography/mass spectrometry.

An analytical method, based on a selective extraction and pyrolysis gas chromatography/mass spectrometry assay of arsenocholine and acetylarsenocholine in aquatic organisms, is described. Characteristic fragmentation patterns were obtained from pyrolytically demethylated compounds. The molecules were rearranged in unique pathways which differed from those of corresponding nitrogen analogues. Qualitative determination of arsenocholine and acetylarsenocholine was achieved by gas chromatographic as well as mass spectrometric analysis of the thermal degradation products (trimethylarsine, dimethylvinylarsine and the demethylated arsenocholine or acetylarsenocholine). Arsenocholine and acetylarsenocholine in fish from industrially polluted water were isolated and identified. Massfragmentographic quantification of the arsenic compounds in fish was carried out by use of deuterium labelled analogues of arsenocholine and acetylarsenocholine as internal standards. The method showed a high sensitivity.

Animals↗