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At least 685 records · Page 38Linked to original sources
PubMed1987

Influence of manure gases on puberty in gilts.

To determine whether manure gases can influence onset of puberty in gilts, 42 crossbred gilts were reared from 10 to 40 wk of age on concrete slats over a 1.22-m deep pit that was drained and refilled with clean water biweekly (clean group). Forty-one gilts were reared over a similar type pit where manure was allowed to accumulate (control group). Treatments were in two separate rooms of the same building with similar feeding, water, floor space, lighting and room temperature. Ventilation fans with timer controls in each room were set so fans in the clean environment ran twice as long as fans in the control environment. Aerial concentrations of ammonia in the control room were fourfold higher than in the clean room (21 vs 5 ppm), while aerial concentrations of hydrogen sulfide were similar. Average daily gain and feed efficiency were similar for both groups [.69 vs .72 kg/d (P = .31) and 1.61 vs 1.54 kg feed/kg gain (P = .52)]. From 20 to 40 wk of age, all gilts were exposed to a mature boar three times weekly, utilizing four boars in rotation. Blood samples were collected weekly from each gilt by venipuncture and analyzed for progesterone to establish time of first ovulation. A greater proportion of gilts in the clean group attained puberty by 24 to 26 wk (P less than .05) and 27 to 29 wk of age (P less than .10) compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1993

Quality specifications for pH and blood gases.

This presentation is built upon experience with use of blood gas results in clinical work during 25 years, experience from the external quality control of 120 blood-gas-analyzers participating in the Norwegian Control Survey 1984-1991, and at last 3 different pH/blood gas inter-analyzer comparisons in Oslo and Bergen in 1980, 1990 and 1992. It is discussed the pure biological variations of the three parameters pH, pCO2 and pO2 as well as the variations in results caused by preanalytical and analytical factors. My proposal for goal of quality for determinations of blood gases (the pure analytical variations, given as EA, Error Allowable) are; pH: 0.02 units on all levels as SD, pCO2: 1-2% (CV) depending on level and the clinical situation. pO2: 2-4% (CV) depending on the level and clinical situation.

Chemistry, Clinical↗
PubMed1992

Solubility of inert gases in PFC blood substitute, blood plasma, and mixtures.

Measurements are reported of the solubility of nonreactive gases, e.g., hydrogen and xenon, in the following liquids: (a) Oxypherol (FC-43 emulsion) blood substitute, (b) blood plasma, (c) mixtures of Oxypherol and blood plasma, and (d) perfluorotributylamine. Typical results for Ostwald solubility at 25 degrees C for Xe gas in various liquids are 0.118 in H2O, 0.12 in blood plasma, and 1.51 in N(C4F9)3. Observed solubilities for the mixtures can be calculated from the relation: L(mixture) = L(emulsion)xv(emulsion) + L (plasma)xv(plasma), in which the v's are the volume fractions in the mixture. This linear relation implies that the gas dissolves independently in each liquid in the mixture. The effect of the emulsifier (Pluronic F-68, 2.6%), on gas solubility in the mixture, is small. Results for the temperature dependence of Ostwald solubility, L(T), in the range 10-37 degrees C are reported.

Blood Substitutes↗
PubMed2001

Combination of advanced oxidation processes and gas absorption for the treatment of chlorinated solvents in waste gases.

Treatment of chlorinated organic compounds in waste gases is difficult because of several reasons: these compounds are dioxin precursors when incinerated, and also biological treatment is difficult because of a limited number of suitable microbial degradation pathways. On the other hand, since the 1990s, a new generation of chemical oxidation techniques has been introduced in water treatment. Advanced Oxidation Processes (AOPs) are based on a combination of UV/H202, UV/O3 or H2O2/O3. The combinations result in the generation of OH-radicals, which subsequently attack the organic pollutants. In this work, the treatment of a gas stream (240 L/h) loaded with 20-40 ppmv trichloroethylene (TCE) is presented. Therefore, a combination of an absorption process in a bubble column with a liquid H2O2/O3 initiated oxidation, was investigated. Removal efficiencies, depending on the dosed H2O2 and O3, up to 94% were found. The production of chloride ions was investigated: the Cl-atoms from the removed TCE could be found back as chloride ions. Next to the experimental work, attention was paid to the mechanisms taking place in the proposed concept. Here, a simulation model was developed, considering gas/liquid mass transfer of TCE and ozone, axial liquid dispersion, advective gas and liquid transport and about 29 chemica reaction steps. The modelling allowed a better understanding of the technique and gives insight in its possibilities and limitations. Finally, it can be concluded that the proposed technique shows interesting perspectives: it is able to transform chlorine in chlorinated solvents into chloride ions effectively at ambient temperature conditions.

Absorption↗
PubMed1992

[Pulmonary distribution of 99mTc-technegas--a comparative study of radioactive inert gases].

99mTc-technegas (99mTc-gas), which consists of fine particles, is produced in carbon crucibles burned at 2500 degrees C. On this study, the particle size of 99mTc-gas was measured and the pulmonary distribution of 99mTc-gas was assessed in 28 patients with various pulmonary diseases. Most particles were 5-30 nm in diameter as determined by electron microscopy. In a clinical study, about 37 MBq of 99mTc-gas was inhaled three times during deep breathing in a sitting position. In a comparative study with radioactive inert gases (133Xe, 81mKr), 99mTc-gas showed a similar distribution to the inert gas in most patients, although some with obstructive disease showed hot spots in the lung fields. In patients with severe obstructive change, marked deposits of 99mTc-gas was noted in the central airways, but 99mTc-gas penetrated to the peripheral lung field. This result suggests that 99mTc-gas can be used to evaluate ventilatory function even in patients with chronic obstructive pulmonary diseases.

Gases↗
PubMed1992

Intravascular bubble composition in guinea pigs: a possible explanation for differences in decompression risk among different gases.

Differences in risk of decompression sickness (DCS) that have been observed among inert gases may reflect differences in gas solubility or diffusivity or both. A higher risk gas might generate a larger volume of evolved gas during decompression, thereby increasing the probability of DCS. If this hypothesis is correct, the composition of bubbles that develop during decompression should reflect such gas differences. Unanesthetized guinea pigs were compressed to depths ranging from 250 to 350 fsw with air, He-O2 (21% O2) or one of a number of N2-He-O2 or N2-Ar-O2 mixtures (21% O2). Animals were held at depth from 15 to 60 min, then decompressed slowly (60 fsw/min) or rapidly (less than 15 s) to 5 fsw. If severe DCS developed, as judged by changes in physiologic variables, death usually occurred quickly. Gas/blood samples were then immediately withdrawn from the right atrium or the inferior vena cava, and the gas phase analyzed for He, N2, Ar, O2, and CO2 via gas chromatography. Bubbles from all dives contained 5-9% CO2, 1-4% O2, with the balance inert gas. Bubbles after N2-He-O2 dives contained substantially more N2 than He (up to 1.9 times more) compared to the dive mixture; bubbles after N2-Ar-O2 dives contained more Ar than N2 (up to 1.8 times more). For N2-He-O2 dives, the actual inert gas makeup of bubbles was dependent on the time-at-depth and the decompression profile. Results may reflect differences among He, N2, and Ar in tissue solubility/diffusivity and gas exchange rates, and support the rank order of increasing DCS risk (He less than N2 less than Ar) and rate of gas exchange (N2 less than He) observed previously during rat dives.

Animals↗
PubMedDate not supplied

[AN experimental study of the action of industrial aerosols and toxic gases on dental status].

Experiments with white rats have demonstrated that exposure to adverse factors of industrial environment (aerosols and gases) results in increased incidence of caries (by 30-40%) and in a more grave course of the carious process. These changes course along with disorders of the metabolic processes, of the blood and salivary enzymatic systems first of all.

Aerosols↗
PubMed1992

Middle ear gases.

The ex vacuo theory, claiming that air enters the middle ear through the Eustachian tube and oxygen leaves it into the blood by diffusion, does not provide a complete explanation and description of the mechanism of middle ear aeration. This study shows that both the gas diffusion between the middle ear and the blood and the flow of gas through the Eustachian tube are bidirectional processes for all the gases concerned N2, CO2, O2 as well as H2O.

Adolescent↗
PubMed2005

[Regional simulation of rice yield change under two emission scenarios of greenhouse gases].

Based on the newest emission scenarios of SO2 and greenhouse gases, i. e., the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2 and B2 scenarios, and by using RCM (Regional Climate Model)-PRECIS and CERES-Rice model, this paper simulated the rice yield change in 2080 at 50 x 50 km scale. The results showed that there was a great range of yield change across whole China. The yield would increase along the Changjiang River and in South China, and decrease in North and Northeast China. Because of the direct effect of CO2 on rice growth, the SRES A2 scenario would be more positive to the increase of rice yield than B2. In 2080, the total rice yield in whole China would increase under A2 emission scenario, while decrease under B2 emission scenario.

Biomass↗
PubMedDate not supplied

[A possible molecular mechanism of the narcotic action of noble gases].

A molecular mechanism of the narcotic action of noble gases is suggested, which is based on the fact that noble gas atoms change the orientation of water molecules absorbed on the surface of axon membrane. The resulting change in the transmembrane potential deteriorates the propagation of nerve pulse.

Animals↗
PubMedDate not supplied

[Monitoring the air in the workplace. Vapors and gases].

In order to control occupational exposure to gases and vapors, the industrial Hygienist use different sampling instruments and analytical procedures to measure directly or indirectly the gas and vapor concentrations in working atmospheres. The main techniques employed are here described.

Environmental Monitoring↗
PubMed1991

Hazards in confinement housing--gases and dusts in confined animal houses for swine, poultry, horses and humans.

Indoor atmospheres in swine or poultry confinement buildings, horse stalls or human dwellings contain gases, dusts and endotoxin in concentrations significantly in excess of those in outdoor environments. Although concentrations of such constituents differ appreciably between species, many of such differences may be related to differences in indoor mass loading and ventilation, or to the homogeneity of such ventilation. The high protein content of these indoor dust particles suggest they are of animal origin. Their ability to form bacterial colonies and to form or bind endotoxin suggest that the smallest and most respirable particles were manure particles containing enteric bacteria and endotoxin. Respiratory disease in swine, poultry and horses and in the workers who care for them may be caused by increased levels of carbon monoxide, ammonia, hydrogen sulfide, or indoor dust particles from feed and manure. The stagnant air of a well-insulated building causes the most active individual to attract these stagnant pockets, while the tendency of young animals to seek warmth may lead to the formation of additional pockets. Increased ventilation is an expensive solution to the problems associated with indoor air pollution. However, more thorough mixing of indoor air may reduce the effects of these clouds of pollutants.

Air Pollutants↗
PubMed1990

[Recent developments in pollutant dosimetry with special reference to water soluble gases].

The paper describes special problems of sampling toxic gases, very soluble in water, on workplaces with passive samplers. It is possible to construct such passive dosimeters which are suitable for the measurement of substances mentioned above if some peculiarities are taken in consideration. The stain-length passive dosimeters are specially analysed. Problems of the accuracy of this dosimeters, caused by inconstancy of the response time, are explained.

Air Pollutants, Occupational↗
PubMed1990

Construction and calibration of a personal passive dosimeter for sampling organic gases and vapours in breathing zone air.

A personal passive dosimeter of the permeation type has been constructed for sampling organic gases and vapours in breathing zone air. In the dosimeter, paper coated with silicone rubber serves as a permeation membrane. The device has been calibrated for 14 organic substances. The experimentally determined sampling rate values for investigated compounds were independent of face air velocity and in almost all cases of compounds' concentration in the air. No difference between sampling rates for single compounds and their mixtures has been observed.

Air Pollutants, Occupational↗
PubMedDate not supplied

[The effect of inert gases on the intensity of lipid peroxidation in the rat liver].

The presence of helium and argon in gas mixtures increases the peroxidation rate of lipids in homogenates and has no influence on this index in the mitochondrial and microsomal fractions of the rat liver. An assumption is advanced that the realization of effects of the inactive gases in question is realized via the plasma membranes of cells.

Animals↗
PubMed1978

Studies of whole-body retention and clearance of inhaled noble gases.

The in vivo measurements of 127Xe and 79Kr clearance from the whole body indicate five components, with biologic half-times ranging from 13 sec to 17.04 h. The slowest component correlated highly with percent total-body fat, the half-time varying between 7.59 and 17.04 for xenon and between 4.20 and 9.62 h for krypton. The long-term retention was localized to regions of high fat content as determined by the coincidence mode of the whole-body counter and images obtained with the scintillation camera. The estimated dose based on the retention data of this study would indicate increased doses to body fat and gonads as compared with those previously calculated. These increased doses are due to the longer retention of noble gases in fat. After 10-min inhalations of a mixture of 127Xe and air and 79Kr and air, approximately one third of the total 127Xe and one fifth of the total 79Kr were transferred to the body tissues, extrapolated back to the start of gas washout. Of this amount, approximately 13% of the 127Xe and approximately 9% of the 79Kr were associated with the slowest component.

Adipose Tissue↗