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At least 289 records · Page 16Linked to original sources
PubMed1976

[Study of the composition of the exhaust gases from the manufacture of feed antibiotics and of fungal and bacterial entomopathogenic preparations].

The main composition of exhaust gases in production of various preparation, such as bacitracin, chlortetracycline, hygromycin, entobacterin, dendrobacillin, boverin and kormogrisin was determined by the method of group chemical analysis and gas chromatography. The exhaust gases contaned fatty acids c2--c6, aldehydes and ketones c2--c6, alcohols c2-c5, amines (diethylamine, triethylamine, etc) and some phenols. The level of the substances was insignificant. However, they were toxic for living beings. The exhaust gases had disagreeable odour.

Animal Feed↗
PubMed1976

Distribution of waste anesthetic gases in the operating room air.

Epidemiologic and animal studies identify a strong relationship between chronic exposure to anesthetic gases and health hazards. Efforts to reduce exposure of personnel require an understanding of the distribution of anesthetic waste gases in the operating room air. Concentrations of nitrous oxide and halothane were measured at numerous stations throughout an operating room and a delivery room in the absence of personnel. Air conditioning flow rates and flow patterns were varied, as was the height of the anesthetic gas source. Air flow patterns were found to dominate the anesthetic gas distribution, while buoyancy effects were negligible. Venting waste gases at the floor does not significantly reduce exposure of personnel. Areas of high concentration were observed; their occurrences and locations varied strongly with air flow patterns. The exhaust grille is the best location for a single measurement of the average room concentration. Recirculating air-conditioning systems reduce energy costs; however, only the non-recirculating portion of the air exchanges reduces waste gas concentrations.

Air↗
PubMed1957

Narcosis and emulsion reversal by inert gases.

Investigations of the effect of high pressures of Na (100 to 130 atmospheres) and of Ar (60 to 80 atmospheres) showed that these gases are effective in reversing the phases of an oil in water emulsion. Nitrous oxide did not cause reversal at pressures as high as 53 atmospheres nor did helium as high as 107 atmospheres. We found CO(2) most effective in reversing the emulsions and attributed this to its chemical properties. It is suggested that these observations may help to explain the narcotic effects of inert gases.

Anesthesia↗
PubMed1965

THE REMOVAL OF SULFUR DIOXIDE FROM FLUE GASES.

The growth of industrialization makes it imperative to reduce the amounts of sulfur dioxide emitted into the atmosphere. This article describes various processes for cleaning flue gases, and gives details of new methods being investigated.Wet scrubbing with water, though widely practised, has many disadvantages. Scrubbing with zinc oxide, feasible in zinc works, is more satisfactory.Dry methods use a solid absorbent; they have the advantage of a high emission temperature.Other methods are based on the addition to the fuel or the flue gases of substances such as activated metal oxides, which react with the sulfur to form compounds less harmful than sulfur dioxide. Also being investigated are a two-stage combustion system, in which the sulfur dioxide is removed in the first stage, and the injection of activated powdered dolomite into burning fuel; the resulting sulfates being removed by electrostatic precipitation.A wet catalysis process has recently been developed.Most of the cleaning processes are not yet technically mature, but first results show good efficiency and relatively low cost.

Air Pollution↗
PubMed1996

Diffusion coefficients and solubility coefficients for gases in biological fluids and tissues: a review.

Based on a review of 166 references for diffusion and solubility coefficients in biological fluids and tissues, we have tabulated experimental values for the gases Ar, CO2, H2, He, N2, Ne, N2O, O2, and SF6. Two major conclusions can be drawn: a) for tissues, there is a scarcity of available data; and b) in general, there are significant differences between values determined by different investigators, the discrepancies being most prominent for diffusion coefficients. For water, we give numeric values of the temperature coefficients and preferred diffusion and solubility coefficients at 25 degrees and 37 degrees C. Further, we describe several methods for estimation of coefficients where experimental data are lacking. For tissues, none of the formulas described give precise predictions for all gases, but rough estimates sufficient for most qualitative work can almost always be found. In particular, the data material indicates that for all tissues other than fatty tissues consisting of mainly triacylglycerols, the solubility coefficients for water may be used as a good approximation. Except for SF6, the error in this approximation probably does not exceed 20%. In contrast, diffusion coefficients for most tissues are from 25 to 50% lower than the respective coefficients in water, generally increasing with the water content of the tissue.

Animals↗
PubMed1980

Intravitreal longevity of three perfluorocarbon gases.

Three gases, perfluoromethane, perfluoroethane, and perfluoropropane (CF4, C2F6, and C3 F8, respectively) were studied for their possible value as intravitreal tamponades in retinal surgery. The gases expand and have intraocular longevities that increase with the length of the carbon chain. A 0.4-cc injection of CF4, remained in the eye six days, twice as long as an equivalent amount of air; C2F6 remained 16 days, more than four times as long as air; and C3F8 remained 28 days, nine times as long as air and four times as long as sulfur hexafluoride.

Air↗
PubMed1984

Intravitreal disappearance rates of four perfluorocarbon gases.

The disappearance rates of bubbles from the vitreous of rabbits were measured for four perfluorocarbon gases. The decay rate for each was found to be exponential and thus independent of the volume injected. Clinical observations indicated that the disappearance of the perfluorocarbon gases in patients also follows exponential decay, but that the half-lives are three to five times longer than in rabbits.

Animals↗
PubMed1989

Kinetics of intraocular gases. Disappearance of air, sulfur hexafluoride, and perfluoropropane after pars plana vitrectomy.

Intraocular gas bubbles are an important source of internal tamponade for the treatment of retinal breaks in eyes requiring vitrectomy. The kinetics of disappearance of air, 20% sulfur hexafluoride, and 10% perfluoropropane were prospectively evaluated in 76 eyes undergoing pars plana vitrectomy. The absorption of each gas approximated a first-order kinetic equation with respect to bubble volume. The half-life of air was 1.6 days in phakic and 0.9 days in aphakic eyes. The half-life of 20% sulfur hexafluoride was 2.8 days in phakic and 2.4 days in aphakic eyes. The half-life of 10% perfluoropropane was 5.7 days in phakic, 4.5 days in aphakic, and 4.3 days in pseudophakic eyes. The difference in half-life among the three gases was significant. Intraocular gases had a shorter half-life in aphakic than in phakic eyes.

Absorption↗
PubMedDate not supplied

Lipid peroxidation: detection in vivo and in vitro through the formation of saturated hydrocarbon gases.

Saturated, short-chain hydrocarbon gases (ethane, propane, etc.--but not methane) are evolved during the spontaneous lipid peroxidation of mouse tissue slices or homogenates. A relatively-selective increase in either ethane or pentane was observed when either linolenic acid or linoleic acid, respectively, was added to tissue homogenates. When mice were challenged by injection of carbon tetrachloride or cumene hydroperoxide (two agents that induce a lipid peroxidative attack on liver), they exhaled ethane. The gas chromatographic detection and monitoring of hydrocarbon gases can serve as an index of lipid peroxidation in vivo.

Animals↗
PubMedDate not supplied

A research on determination of explosive gases utilizing cataluminescence sensor array.

In this paper, we propose a model of a sensor array system, which consists of three cataluminescence sensors based on nanosized SrCO3, gamma-Al2O3 and BaCO3 as catalysts, for quantitative analysis of the explosive gases of propane, n-butane and iso-butane in a mixture. Six linear regression equations of the cataluminescence intensity vs. the gas concentrations in the range 2000-10,000 ppm were established from the sensor array system at two working temperatures, as the explosive gases show different sensitivity to the three sensors. The least squares method was employed for solving the simultaneous equations and quantifying the concentrations of the three components. The detection limits (3sigma) of propane, n-butane and iso-butane on SrCO3, gamma-Al2O3 and BaCO3 sensors are 50, 40 and 20 ppm, 80, 60 and 40 ppm, and 20, 10 and 5 ppm, respectively. The concentrations of two artificial samples containing the tertiary mixture were analysed with satisfactory results.

Aluminum Oxide↗
PubMed2005

Flared gases and other pollutants associated with air quality in industrial areas of Nigeria: an overview.

Nigeria, like any other developing nation, is faced with the twin problem of development without destruction. Industrialization, though an important component of development, has had a large share in the despoilation of air quality in the country by the release of high amounts of pollutants into the atmosphere. Petroleum hydrocarbons from refineries, flared gases, dusts, and fumes of metal-smelting and cement works, odorous gases of chemical and allied industries, carbon monoxide and oxides of sulfur and nitrogen of internal combustion engines, the charred particulates and sulfur dioxide emissions of the steel industries etc., all constitute pollutants or co-pollutants of the Nigerian atmosphere. This review article gives an insight into the phenomenal concentrations of some of these pollutants in the Nigerian atmosphere, which point to their unsafe levels and concomitant health risks. It is against this background that there should be continuous but sound monitoring exercise of the Nigerian environment, devoid of the peculiar mix of politics and science, in order to properly audit the quality of air, especially in areas of heavy industrial pollution. Such checks and balances would provide empirical data to assess the various trade-offs of atmospheric pollution in industrial areas of the country such as the Niger Delta region where oil and gas are produced. There should also be enforcement, thereof, of all existing and/or revised standards or regulations such as the compliance limits of the Department of Petroleum Resources (DPR) or the erstwhile Federal Environmental Protection Agency (FEPA).

Air Pollutants↗
PubMed1998

Signal dynamics in magnetic resonance imaging of the lung with hyperpolarized noble gases.

The nonequilibrium bulk magnetic moment of hyperpolarized (HP) noble gases generated by optical pumping has unique characteristics. Based on the Bloch equations, a model was developed describing the signal dynamics of HP gases used in magnetic resonance imaging (MRI) of the lung with special consideration to the breathing cycle. Experimental verification included extensive investigations with HP 3He and 129Xe during both inspiration and held breath in live guinea pigs. Radial acquisition was used to investigate the view variations with a temporal resolution of 5 ms. Agreement between theoretical predictions and in vivo results was excellent. Additionally, information about effects from noble gas diffusion and spin-lattice relaxation was obtained. In vivo results for T1 were 28.8 +/- 1.8 s for 3He and 31.3 +/- 1.8 s for 129Xe. Comparison with in vitro data indicated that relaxation in the pulmonary gas space is dominated by dipolar coupling with molecular oxygen. The results provide a quantitative basis for optimizing pulse sequence design in HP gas MRI of the lung.

Animals↗
PubMed2002

Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials, and organisms.

The sensitivity of conventional nuclear magnetic resonance (NMR) techniques is fundamentally limited by the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This review describes the principles and magnetic resonance applications of laser-polarized noble gases. The enormous sensitivity enhancement afforded by optical pumping can be exploited to permit a variety of novel NMR experiments across numerous disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, NMR sensitivity enhancement via polarization transfer, and low-field NMR and MRI.

Chemical Phenomena↗
PubMed2005

Effect of ischemic preconditioning on brain tissue gases and pH during temporary cerebral artery occlusion.

Previous studies have demonstrated that a brief period of ischemia protect against subsequent severe ischemic insults to the brain, i.e. preconditioning. We evaluated the effects of ischemic preconditioning, produced by 2 min proximal temporary artery occlusion, on brain tissue gases and acidity during clipping of cerebral aneurysm. Twelve patients with aneurysmal subarachnoid hemorrhage were recruited. All patients received standard anesthetics. After craniotomy, a calibrated multiparameter catheter was inserted to measure oxygen (PtO2) tension, carbon dioxide (PtCO2) tension and pH (pHt) in tissue at risk of ischemia during temporary artery occlusion. In patients assigned to the preconditioning group, proximal artery was occluded initially for 2 min and was allowed to reperfuse for 30 min. All patients underwent cerebral artery occlusion for clipping of aneurysm. The rate of change in PtO2, PtCO2 and pHt after artery occlusion were compared between groups using unpaired t test. Baseline brain tissue gases and pHt were similar between groups. Following artery occlusion, the decline in PtO2 and pHt were significantly slower in the preconditioning group compared with the routine care group. These results suggested that ischemic preconditioning attenuates tissue hypoxia during subsequent artery occlusion. Brief occlusion of the proximal artery may be a simple maneuver for brain protection during complex cerebrovascular surgery.

Adult↗
PubMed1988

Role of diffusion shunt in transfer of inert gases and O2 in muscle.

Diffusion shunt is diffusive gas exchange between arterial and venous vessels. Evidence for diffusion shunt had been obtained in washout studies in the gastrocnemius muscle of the dog. According to models, diffusion shunt is expected to be enhanced at low blood flow, and for gases of high diffusivity. Shunting of O2 should be reduced in comparison to inert gases because of chemical binding in blood.

Animals↗
PubMed1980

Solubility of inert gases in dog blood and skeletal muscle.

Solubility of H2, Ar, CH4 and SF6 was determined at 310 K (37 degrees C) in water, in saline (0.154 mol NaCl/l H2O), in plasma and whole blood of dogs, and in homogenates of the dog gastrocnemius muscle. The liquids were equilibrated with pure gases, and the dissolved gases were extracted and measured by gas chromatography as described previously (Meyer, M.: Pflügers Arch. 375, 161--165, 1978). In saline, the solubilities were 4% (SF6) to 15% (Ar) lower than in water. For dog blood the following mean values for the solubility coefficient (in mumol . 1(-1) . kPa-1) were found: for H2, 6.44; for Ar, 9.94; for CH4, 11.44; for SF6, 2.62. The red cell/plasma and the muscle/blood solubility ratios were near unity for H2, Ar and CH4 (ranging from 0.9 to 1.3); for SF6, however, they were much higher (about 2.1), apparently due to the high solubility of SF6 in hydrophobic substances (lipids).

Animals↗
PubMed1998

Tumor implantation following laparoscopy using different insufflation gases.

BACKGROUND: Laparoscopic manipulation of malignancies is associated with an increased incidence of metastasis to port sites in experimental models. This study investigated the effect of different insufflation gases on the implantation of a tumor cell suspension following laparoscopic surgery in an established small animal model. METHODS: Forty Dark Agouti rats underwent laparoscopy and the introduction into the peritoneal cavity of a tumor cell suspension. The insufflating gas used for each procedure was one of the following gases (10 rats in each group): carbon dioxide (CO2), nitrous oxide (N2O), helium, and air. The rats were killed 7 days after surgery, and the peritoneal cavity and port sites were examined for the presence of tumor. RESULTS: Although no significant differences were seen between air, CO2, and N2O insufflation groups, tumor involvement of peritoneal surfaces was less likely following helium insufflation. CONCLUSION: The results of this study suggest that tumor metastasis to port sites following laparoscopic surgery may be influenced by the choice of insufflation gas. In this study, helium was associated with reduced tumor growth.

Adenocarcinoma↗
PubMed1989

Emission of viable bacteria in the exhaust flue gases from a hospital incinerator.

The exhaust gases from an oil-fired hospital waste incinerator were examined during normal incinerator operation. The design-specified operating temperature was 800 degrees C in the primary combustion chamber and 1000 degrees C in the secondary chamber. Flue gas temperatures, measured from the sampling point at the base of the exhaust stack, varied over the range 186-305 degrees C, and bacteria were recovered from this position in numbers up to 400 cfu m-3 (mean 56 cfu m-3). No sampling was performed at the top of the stack where flue gases were discharged to the atmosphere. Isolates were predominantly gram positive, i.e. Bacillus spp., coagulase negative staphylococci and Staphylococcus aureus, although low numbers of gram negative species (Pseudomonas fluorescens and other pseudomonads) were also recovered. Our results suggest that incineration may not constitute an absolute method of sterilization for clinical waste.

Air Pollutants↗