Gas exposure

TPD is frequently used to detenuine (relative) surface coverages. The area below a TPD spectrum of a certain species is proportional to the total amount that desorbs. In this way one can detennine uptake curves that correlate gas exposure to surface coverage. If tire pumping rate of the UHV system is sufiBciently high, the mass spectrometer signal for a particular desorption product is linearly proportional to the desorption rate of the adsorbate [20, 21] ... 

Test method for porosity in gold platings on metal substrates by gas exposures Test method for half-cell potentials of uncoated reinforcing steel in concrete Method for detection of copper corrosion from petroleum products by the copper strip tarnish test... 

With a sparingly soluble gas a much higher partial pressure of that gas is in equilibrium with a solution of a given concentration than is the case with a highly soluble gas. Exposure of a solution to any atmosphere will lead to the take-up, or release, of gas until equilibrium is eventually attained. 

In the case of ethylene oxide sterilization, rather more detail is included on the information expected in an MAA description of the sterilizer and associated facilities, the gas concentration used, bioburden monitoring and limits prior to exposure to gas, gas exposure time, temperature and humidity prior to exposure and during the exposure cycle, and the conditions under which ethylene oxide desorption is undertaken. 

The third block in Fig. 2.1 shows the various possible sensing modes. The basic operation mode of a micromachined metal-oxide sensor is the measurement of the resistance or impedance [69] of the sensitive layer at constant temperature. A well-known problem of metal-oxide-based sensors is their lack of selectivity. Additional information on the interaction of analyte and sensitive layer may lead to better gas discrimination. Micromachined sensors exhibit a low thermal time constant, which can be used to advantage by applying temperature-modulation techniques. The gas/oxide interaction characteristics and dynamics are observable in the measured sensor resistance. Various temperature modulation methods have been explored. The first method relies on a train of rectangular temperature pulses at variable temperature step heights [70-72]. This method was further developed to find optimized modulation curves [73]. Sinusoidal temperature modulation also has been applied, and the data were evaluated by Fourier transformation [75]. Another idea included the simultaneous measurement of the resistive and calorimetric microhotplate response by additionally monitoring the change in the heater resistance upon gas exposure [74-76]. 

The failure of physostigmine to reverse BZ effects during the first 8 hours (Fig. 8) is interesting and unexplained. It reminds one of the Berry and Davies findings (in 1970 at the British labs in Porton Down) which showed that the reversible anticholinesterase pyridostigmine was paradoxically effective as a prophylactic agent in the event of nerve gas exposure (see ref. ). 

Studies by Enoch Callaway (and others) at Edgewood, in the 1950s, demonstrated mild but significant cognitive impairment at total doses of 4 mg, but not 2 mg. This was important in selecting the dose to be provided in syrettes. Atropine syrettes containing 2 mg of atropine are included in each soldier s equipment whenever the possibility of nerve gas exposure appears likely. The contents of the syrette are to be self-injected... 

Saccharine-particle method, for respiratory tract gas exposure, 297... 

Welders are typically exposed to a complex mixture of dust and fume of metallic oxides, as well as irritant gases, and are subject to mixed-dust pneumoconiosis with possible loss of pulmonary function this should not be confused with benign pneumoconiosis caused by iron oxide. Although an increased incidence of lung cancer has been observed among hematite miners exposed to iron oxide, presumably owing to concomitant radon gas exposure, there is no evidence that iron oxide alone is carcinogenic to man or animals. ... 

Dikshit RP, Kanhere S Cancer patterns of lung, oropharynx and oral cavity cancer in relation to gas exposure at Bhopal. Cancer Causes Control 10(6) 627-636, 1999... 

Kennedy SM, Enarson DA, Janssen RG, et al. 1991. Lung health consequences of reported accidental chlorine gas exposure among pulp mill workers. Am Rev Respir Dis 143(l) 74-79. 

Chlorine is a pungent suffocating gas, exposure to which can cause irritation of the eyes, nose and throat burning of mouth coughing choking nausea, vomiting dizziness and respiratory distress. Exposure to 15—20 ppm of chlorine in air can cause irritation and coughing. A 30 minute exposure to... 

Gas exposures are reported in units of Langmuir (1 Langmuir = 1 L = 1x10 torr-sec), uncorrected for ion gauge sensitivity and doser enhancement. Coverages, 0, are reported relative to the unreconstructed Au(lll) surface atom density (0 = 1 corresponds to 1.39x10 5 atoms/cm ). 

Beebe, in a later study mainly on cancer, included some data on tuberculosis. These data (Table 4-5), although suggestive of a residual effect from mustard-gas exposures, were not statistically significant. 

SAS. Salmonella typhimurium TA1S3S, reverse mutation (gas exposure) + + 3% in air Araki et al. (1994)... 

Gas adsorption is studied at pressures between 5 x 10 and 1 x 10 5 torr and at temperatures between 210 and 530 K. Surface structures are observed both with increasing exposure and after the gas is pumped away. Neither gas exposures nor background pressures are corrected for ion gauge sensitivity. 

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