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At least 19 recordsLinked to original sources
PubMed1979

[Studies on the performance of the dental air turbine handpieces. (Part 1). Air pressure and bur length to be influenced over the rotational performance of the air bearing type handpieces (author's transl)].

Air turbine handpieces are used as the dental cutting instruments for the clinical use and many appliances. But, there are no studies on the performance of air turbine handpieces. So, this paper shows the rotational performance of air turbine handpieces which are influenced over the supplying air pressure and cutting bur length. Experimentally used air turbine handpieces is air bearing type and it's set up air pressure to be supplied is 3.5 kg/cm2. So, in this experiments, the range of air pressure is 1.8 approximately 3.5 kg/cm2, which is established five stages. And the bur length of the rotational parts is 5 approximately 9 mm with five steps. As the results, the rotational performance of air handpieces are influenced over these factors of the air pressure and the bur length. And air pressure to be supplied are influenced to be not only over the rotational speed but the load for the putting a stop to the revolutions.

Air Pressure↗
PubMed1975

Experimentally determined tissue air ratios and scatter air ratios for collimated beams of 14 mev neutrons.

Tissue air ratios (TAR) and scatter air ratios (SAR) for collimated beams of 14 MeV neutrons were determined from depth dose curves measured in air and water using a tissue equivalent proportional counter. Central axis depth dose data were obtained as a function of field size and depth in a water phantom for an SSD or 125 cm. The collimator was composed of steel and polyethylene and was continuously variable from a 3 times 3 cm to a 20 times 20 cm field size at 125 cm SSD. The field scans for this collimator were flat within plus or minus 2 per cent over 80 per cent of the field dimension in air and were reduced to 20 per cent of the central axis dose at 1-2 field radii in air. Relative depth dose data in air and phantom were measured with an accuracy of plus or minus 2 per cent and were used for the TAR and SAR calculations. The resulting scatter air ratios for 14 MeV neutrons have roughly the same characteristics as 60-Co SAR, but are 60 per cent larger at maximum build-up and reach that maximum at about 60 per cent of the peak depth for 60-Co for all field sizes. The effects of collimator throat scatter on the central axis depth dose characteristics of this particular collimator design are discussed in detail using the measured tissue and scatter air ratios.

Absorption↗
PubMed1975

An epidemiologic approach to community air lead exposure using personal air samplers.

Accurate information on the relationship between blood lead and air lead is essential to any consideration of the possible effect of air lead on the body burden. Past studies of occupationally exposed workers have established that such a relationship exists at high levels of air lead exposure. No such information has been available for subjects exposed to the low air lead levels representative of present-day community exposure. Past studies in this area have suffered from inadequate information on actual lead exposure at the air lead levels of concern. Researchers have has to rely on air lead data obtained from stationary samp;ing stations. Because wide variations can exist betwween locations within a city such information could not be assumed to represent the exposure of any individual subject. At lbest they can be considered only approximations of actual exposures. The Naational Research Council recognized the deficiencies of past studies in their report "Airborne lead in perspective" and recommended that "more precise studies are needed of the relation between atmospheric lead in the urban environment and the concentration of lead in the blood, perphaps by the use of personal monitors". This paper describes the study which was undertaken to evaluate the effect of air lead exposure as measured with personal air sampling devices on indices of lead absorption such as blood lead, urine lead, DALA and ALAD activity...

Absorption↗
PubMed1979

The effect of air ionization on the air-borne transmission of experimental Newcastle disease virus infections in chickens.

The effect of artificial air-ionization on air-borne transmission of Newcastle disease virus (NDV) infection in chickens was studied in an isolated system consisting of two side-by-side cages with solid walls and a wire-gauze roof. During a 3-week observation period more than 90% of the uninoculated indicator chickens, housed in one of the cages, contracted the virus shed to the air by the NDV-inoculated, diseased birds in the neighbouring cage. This air-borne transmission of NDV was completely prevented by increasing the ion concentration in the test room by a constant negative corona discharge above the wire-gauze roof. On the other hand, spreading of the infection within a group of chickens housed in a single cage was not affected by air ionization. These and other results suggest that artificial air-ionization may protect animals from certain air-borne infections by interfering with microbial aerosol formation and/or by facilitating their decay.

Air Ionization↗
PubMed1976

Head and neck cooling by air, water, or air plus water in hyperthermia.

The effects of air, water, and air plus water head cooling on thermoregulatory responses and human operator performance were studied in nonacclimatized, heat-exposed men. Forty chamber exposures (46 degrees C, 30 mm Hg water vapor pressure) were conducted under noncooled and the aforementioned subconditions of head cooling. Five subjects, exposed for 80 min, were monitored for mean skin and rectal temperatures, heart rate, sweat loss, and compensatory tracking performance. A modified Air Force helmet shell provided facial air ventilation (24 degrees C) at 8 cfm. Eight interconnected neoprene modules fastened beneath a helmet linear provided water cooling (20 degrees C at 0.9 l/min). Tracking performances was unchanged across conditions. Elevation of rectal temperature and heart rate, sweat loss, and Physiological Index of Strain were significantly reduced by each condition of head cooling. Air is as effective as water as a cooling agent. Air ventilation acts synergistically with water cooling in reducing physiological strain. Relative merits of each approach to head cooling, in an operational context, are discussed.

Adult↗
PubMed1975

[Variance of the air sample in air analysis demonstrated on a sample of atmospheric aerosol].

Particulate matter, sampled during 24-h periods from 200 m-3 urban air, was collected on cellulose filters. Each of the four quarters of the filters was analyzed separately by atomic absorption spectroscopy; the concentration of 11 metals was so determined. The residual standard deviation among the quarters of the filter was 10%. In view of this deviation among the results, attributed to the variance of the air sample, it seems rather doubtful that the intercomparison of air sampling instruments, using ambient air as common "standard", will ever give reliable results. It seems likely that air samples, smaller than the 200 m-3 used here, will show an even greater variance, at least with regard to some specific pollutants.

Air Pollution↗
PubMed1992

[Legionella and other bacteria in air humidifiers and cooling systems of air conditioning units--a survey].

Air humidifiers using cold water and cooling towers of air-conditioning systems provide the best settings for the growth of bacteria. Hence, we investigated 90 water samples for humidifiers and 15 water samples from cooling towers of hospitals, authorities, schools, and factories. The colony forming units/ml at 20 degrees C and 36 degrees C, the biological activity of added biocidal substances, and the occurrence of legionella were determined. About 90 percent of the samples showed no activity of the biocidal substance added, suggesting the uselessness of such substances. Furthermore, they exercised neither an influence on the CFU of the water samples nor on the occurrence of legionella. Legionella were isolated in 7 per cent of the humidifiers investigated, in 3 per cent of air conditioned buildings, respectively. 13 per cent of the cooling towers contained legionella. The risk of infection by air conditioning systems, humidifiers, cooling towers, and other emitters of infections agents should be controlled by the public health service.

Air Conditioning↗
PubMed1978

Efficiency of bacterial filtration in various commercial air filters for hospital air conditioning.

Filtration efficiency of high-efficiency particulate air (HEPA) filters is said to be over 99.97% of removal rate against the mist of thermogenerating-type of dioctyl phthalate with average particles diameter of 0.3 micrometer, as tested by the U.S. Military Standard 282 (1956). Filtration of bacterial aerosols through commercial air filters was tested to examine the efficiency of bacterial filtration with eight kinds of air filters. Percentage of bacterial filtration efficiency (% BFE) of three kinds of HEPA filters showed 100% BFE, while NBS-95 and NBS-85 showed over 99% BFE. BFE of NBS-75 air filter was 91.75%.

Aerosols↗
PubMed1975

Airborne infection in a fully air-conditioned hospital. I. Air transfer between rooms.

Measurements have been made of the extent of air exchange between patient rooms in a fully air-conditioned hospital using a tracer-gas method. When the rooms were ventilated at about six air changes per hour, had an excess airflow through the doorway of about 0.1 m.3/sec. and the temperature difference between rooms and corridor was less than 0.5 degrees C., concentrations of the tracer in rooms close to that in which it was being liberated were 1000-fold less than that in the source room. This ratio fell to about 200-fold in the absence of any excess airflow through the doorways. Considerable dilution took place along the corridors so that the concentration fell by around 10-fold for every 10 m. of corridor.

Air Conditioning↗
PubMed1975

Airborne infection in a fully air-conditioned hospital. II. Transfer of airborne particles between rooms resulting from the movement of air from one room to another.

Experiments were conducted simultaneously with gas and particle tracers to determine the relative loss of particles between source and recipient sites in the hospital ward units. The magnitude of this loss could be accounted for by the assumption of sedimentation from well-mixed air masses during the time required for movement between source and recipients sites. As a consequence of this loss the degree of isolation between patient rooms for airborne particles was between 4 and 25 times greater than that for gaseous contamination, which reflects the actual transport of air between the rooms. The design and construction of portable spinning-disk particle generators suitable for field studies is discussed.

Air Conditioning↗
PubMed1977

[The determination of resort and stress-areas by air pollution 2. communication: the evaluation of air pollution in spreadout areas, classification into stress-categories (authors transl)].

To qualify the air pollution by SO2 and particulate matter in wide spreaded areas a method for complex terrain was used in the Austrian Alps. The working model which was chosen is described in report 1. It is possible to classify the investigated area according to stress-categories by adjusting the data. For the qualification of results of measurements for dust fall the criterias were used according to KOFLER and BENGER. Two different situations were considered for the separation of limits for the stress-categories for SO2: areas which are polluted in first line by area sources, and areas which are polluted in first line by point sources.--The limits which were used in the study of Salzburg are introduced and discussed.--According to the method which is described above all municipalities of Tyrol and Salzburg were classified in stress-categories during to their air quality. The results are introduced.

Air Pollution↗
PubMed2026

Indoor Air Quality (IAQ) analysis and 16S rRNA gene sequencing of indoor air pollutants in a 3000-capacity religious auditorium.

A thorough molecular and environmental evaluation of microbial isolates and indoor air quality (IAQ) at a place of worship is presented in this work. The study used a dual-methodological approach, including systematic environmental monitoring to assess occupant health concerns and 16S rRNA gene sequencing for taxonomic identification. Four different bacterial isolates were successfully identified by molecular analysis using BLAST and phylogenetic reconstruction: Bacillus tropicus (A11), Leclercia adecarboxylata (A12), Acinetobacter sp. (A13), and Escherichia coli (A14). The evolutionary position of isolate A13 indicated possible horizontal gene transfer, underscoring the existence of flexible, opportunistic pathogens within the indoor environment, whereas isolates A11 and A14 demonstrated significant genetic stability. Concurrently, six sessions of air quality monitoring showed a thermally demanding environment, with humidity (56.00-70.51%) and temperatures (29.21-33.79 °C) continuously surpassing ASHRAE guidelines. The average pollutant concentrations are within WHO and USEPA safety criteria, however, there were outliers that may suggest sporadic pollutant penetration (outdoor) or resuspension of dust. The results demonstrate a clear relationship between increased chemical pollutants (TVOCs) and reduced thermal comfort. To reduce the congregation's acute respiratory and cardiovascular risks, optimal ventilation systems and source-control measures are urgently needed, as evidenced by the presence of clinically relevant microorganisms combined with dangerous pollution levels.

Analysis↗
PubMed1975

On the muscular fuel of the air sac in an air breathing fish.

The hyohyoideus muscle which is responsible for inflating and contracting the air sac in an air breathing fish, Amphipnous cuchia, belongs to white fibre type as it lacks muscle myoglobin. The muscle shows appreciable amount of glycogen and extracellular phospholipid globules. Staining of I bands in the muscle fibres with Alcian blue (1.0 less than or equal to pH less than or equal to 3.0) indicates presence of acid mucosubstances. The muscle does not show change in phospholipid content at the histochemical level but lowering of glycogen content (25 to 30%) when put to 51/2h of continuted physiological exercise. At the same time, increase in blood sugar level (20 to 30%) possibly indicates utilization of glycogen as the source of energy by the muscle. However, a clear cut priority of glycogen or phospholipid break down for energy source by the muscle could not be established.

Animals↗
PubMed1979

Air-borne fungi in the air of Barcelona (Spain). II. The genus alternaria.

The genus Alternaria Nees formed one of the more important components of the fungus population of the air at Barcelone (Spain), during a two-year study, from February 1976 through January 1978. Results were based only on studied of colonies obtained by gravity-exposed plates. The occurrence of this genus was greatly affected by climatic conditions. In general. however, Alternaria appeared to prefer warmer weather. A total of six species of Alternaria was identified, of which, Alternaria alternata (Fries) Keissler was by far the commonest, representing 71.3% of all colonies.

Air Microbiology↗
PubMed1977

Shallow habitat air dives I and II: human hematologic responses to compressed air saturation diving.

Two subjects each were exposed to pressure equivalents of 50 (SHAD I) and 60 (SHAD II) feet of sea water gauge (FSWG) for 30 and 28 d, respectively. Red blood cell (RBC) count, hemoglobin (Hb) content, and reticulocyte count of venous blood from divers were measured before, during, and after these exposures. RBC count of the divers decreased a maximum of 7.1% in the 50-ft dive and 10.7% in the 60-ft dive compared to surface control values. Hb content fell 7.7% and 11.1% in the 50- and 60-ft dives, respectively, when compared to nondiving subjects. Reticulocyte counts tended to increase late in the pressurization phase and during the recovery. The total month-long responses of Hgb in SHAD I, and RBC, Hgb, and reticulocyte count in SHAD II were significantly altered when compared to those of the surface control subjects. The changes in these factors were directly attributable to the month-long exposure to the total hyperbaric environment. The threshold for hematological effects of chronic exposure to compressed air would seem to lie between 50 and 60 FSWG.

Air↗
PubMedDate not supplied

[Relationship of the content of carboxyhemoglobin in the blood and of carbon monoxide in the expired air of test subjects to the CO concentration in the air of a hermetic chamber].

Four manned experiments (4 test subjects participating in each) were carried out in a chamber of 24 m3. The effect of CO at a concentration of 10 to 45 mg/m3 on the content of carboxyhemoglobin in the blood, nonhemoglobin iron in the plasma, CO in the breathing air, catalase and peroxidase activity was studied. A correlation was found between these parameters and CO concentration in the atmosphere and exposure time. It was demonstrated that a continuous exposure (up to 90 days) to CO at a concentration of 10 mg/m3 under favorable microclimatic conditions produced no significant effect on the above mentioned biochemical paramters.

Atmosphere Exposure Chambers↗
PubMed1977

Distribution of some hydrocarbons in ambient air near Delft and the influence on the formation of secondary air pollutants.

The relative concentrations of hydrocarbons in the atmosphere may provide information concerning their origin. It appears that the hydrocarbon composition measured in Delft (The Netherlands) is entirely different for northern and southern wind directions. This points to different sources. The most important sources for this area are natural gas leaks, traffic, and (petrochemical) industries. It appears that the relative potential of the precursor mix to form peroxyacetylnitrate (PAN) and ozone is also different for both wind directions.

Air Movements↗