Environmental chambers

Three approaches have been identified that reduce susceptibility of CA resists to airborne contamination. In the first, process engineering changes such as the addition of special activated carbon filters to the environmental chambers surrounding the exposure tools (76,79), overcoating the resist with a soluble protective film to isolate the resist from the environment (77,80,81), or modifications of the process flow to minimize the time interval between exposure and post-exposure bake have been shown to improve CA resist processibibty. 

Arnold Engineering Development Center, Test Facilif Data Base, Vol 3 Aerothermal Test Facilities, Aeroballistic andImpactPanges, and Space Environmental Chambers, Arnold Air Eorce Base, Term., Oct. 1988. 

Rockwell hardness testing has been extended to both low and high temperature regimes usually by enclosing the sample and part of the machine in an environmental chamber and using extensions for the anvil and indenter. 

The other method is the ASTM cup method (34). In this method a desiccant is placed in a waterproof dish. The dish is covered with the experimental film and placed in an environmental chamber. The temperature and humidity ate set for the conditions of interest, typically 37.8 °C and 90% th. At regular intervals, the dish is removed and weighed. After a few days enough data have been gathered to describe a steady-state rate of weight gain, and the WVTR can be calculated. Typical experiments take about a week to complete. 

Sample is air from an environmental chamber containing the building material or consumer product. 

Doyle, G.J., Lloyd, A.C., Darnall, K.R., Winer, A.M., Pitts Jr., J.N. (1975) Gas phase kinetic study of relative rates of reaction of selected aromatic compounds with hydroxy radicals in environmental chamber. Environ. Sci. Technol. 9, 237-241. 

Mechanical Property Testing. Mechanical tests were performed on both unirradiated and irradiated materials at -157°C, 24°C, and 121°C. Specimens were kept dry prior to testing in an environmental chamber mounted in a tensile testing machine. Tensile test specimens of [0]4, [10]4, [45]4, and [90]4 laminates were cut from 4-ply composite panels. All specimens were straight-sided coupons. For tension and shear tests the length/width aspect ratio was 8. For the compression tests the aspect ratio was 0.25 and the unsupported length was 0.64 cm. The [0]4 laminates were used to measure the ultimate tension and compression strength, Xit the axial... 

A small 3 cm x 3.5 cm section of the catalyst-coated desiccant wheel (25 cm diameter) was cut and placed in specially made holder shown in Fig. 12.9-6a. The piece of sample was tested in a 0.2 m3 environmental chamber at Chiaphua Industries Ltd. (Fig. 12.9-6b) for reduction of airborne VOC. The chamber was filled with the target VOCs through two stage saturators shown in Fig. 32b. Once the VOC level in the chamber stabilized, the fan was turned on to circulate the air through the sample. Three sets of sensors were located at the inlet and outlet of the holder, as well as in the center of the chamber. The chamber temperature and relative humidity were kept constant during the test. Figure 12.9-6c shows the results for VOC levels of 4000, 2000 and 1000 ppb at room temperature. The reduction rate was slower because of the low VOC concentration and the poor air circulation in the chamber. Also unlike the Prototype Unit, the catalyst was kept at room temperature throughout the test. 

PEFC) stacks, components and entire systems, in off-grid, and grid-connected configurations, with a capacity of up to 100 kW electrical power output. The facility consists of an automated and computerised fuel cell test station, gas analysers, a multi-axial vibration system which is housed in a walk-in environmental chamber (for controlling temperatures, humidity, shocks and vibrations) and ancillary equipment. The data obtained are complementary to and validate fuel cell simulations and models with reference to operation modes, components and system characteristics 1 ... 

McAfee, J. M., J. N. Pitts. Jr., and A. M. Winer. In-situ Long-path Infrared Spectroscopy of Photochemical Air Pollutants in an Environmental Chamber. Paper No. 125 Presented at the Pacific Conference on Chemistry and Spectroscopy, San Francisco, California, October 16-18, 1974. (American Chemical Society—lOth Western Regional Meeting and Society for Applied Spectroscopy—13th Pacific Meeting)... 

During controlled exposures of human subjects to specific compounds like ozone, the concentrations of suspended particles and trace gases must be known and minimized to ensure that health effects can be attributed solely to ozone. The air purification units for the environmental chambers are designed to remove most of the particles and pollutant gases from the ambient air. Prefilters and efficient absolute filters are used to remove 99% of the particles with diameters of 0.3 nin... 

Carboxyhemoglobin Concentration [HbCO] This can be estimated with the method of Jones and co workers. The subject holds a deep breath for 20 s to allow equilibration of carbon monoxide between alveolar air and blood and then expires a sample of that air into a container. The air carbon monoxide concentration may be directly related to carboxyhemoglobin concentration [HbCO]. The test can be performed before exposure in an environmental chamber to help to verify that the subject has not received inordinate ambient pollutant exposure. 

In studies by Kerr et a/., 20 healthy adults—19 males and one female, aged 21-60 years (including 10 smokers and 10 nonsmokers)— were exposed to ozone at 0.5 ppm for 6 h in an environmental chamber. During this period, they engaged in two 15-min medium-exercise ses-... 

Kerr, H. D., T. J. Kulle, M. L. Mcllhany, and P. Swidersky. Effects of ozone on pulmonary function in normal subjects. An environmental-chamber study. Amer. Rev. Respir. Dis. 111 763-773, 1975. 

Hill, A. C. A special purpose plant environmental chamber for air pollution studies. J. Air Pollut. Control Assoc. 17 743-748, 1%7. 

The gas-phase reaction of N2O5 and naphthalene in an environmental chamber at room temperature resulted in the formation of 1- and 2-nitronaphthalene with approximate yields of 18 and 7.5%, respectively (Pitts et ah, 1985). The reaction of naphthalene with NOx to form nitronaphthalene was reported to occur in urban air from St. Louis, MO (Randahl et ah, 1982). The gas-phase reaction of naphthalene with OH radicals yielded phthalaldehyde, phthalic anhydride, phthalide, 1,4-naphthoquione, cis- and rra/J5-2-formylcinnamaldehyde, and 2,3-epoxy-1,4-naphthoquinone. 

Tuazon et al. (1984a) investigated the atmospheric reactions of TV-nitrosodimethylamine and dimethylnitramine in an environmental chamber utilizing in situ long-path Fourier transform infared spectroscopy. They irradiated an ozone-rich atmosphere containing A-nitrosodimethyl-amine. Photolysis products identified include dimethylnitramine, nitromethane, formaldehyde, carbon monoxide, nitrogen dioxide, nitrogen pentoxide, and nitric acid. The rate constants for the reaction of fV-nitrosodimethylamine with OH radicals and ozone relative to methyl ether were 3.0 X 10 and <1 x 10 ° cmVmolecule-sec, respectively. The estimated atmospheric half-life of A-nitrosodimethylamine in the troposphere is approximately 5 min. 

Chemical/Physical. In an environmental chamber, nitrogen trioxide (10,000 ppb) reacted quickly with phenol (concentration 200 ppb to 1.4 ppm) to form phenoxy radicals and nitric acid (Carter et al., 1981). The phenoxy radicals may react with oxygen and nitrogen dioxide to form quinones and nitrohydroxy derivatives, respectively (Nielsen et al, 1983). 

In this paper, the volatilization of five organophosphorus pesticides from model soil pits and evaporation ponds is measured and predicted. A simple environmental chamber is used to obtain volatilization measurements. The use of the two-film model for predicting volatilization rates of organics from water is illustrated, and agreement between experimental and predicted rate constants is evaluated. Comparative volatilization studies are described using model water, soil-water, and soil disposal systems, and the results are compared to predictions of EXAMS, a popular computer code for predicting the fate of organics in aquatic systems. Finally, the experimental effect of Triton X-100, an emulsifier, on pesticide volatilization from water is presented. 

Environmental Chamber. The model disposal system was placed in an environmental chamber (Figure 1). Details of the chamber and its use are discussed elsewhere (18). The chamber was designed so... 

Figure 1. Environmental chamber. A, air entrance B, air exit C, hygrotherm D, temperature and humidity probe E, Pyrex tray F, crystallizing dish G, air dispersion tube H, 12 rubber stoppers (covered with aluminum foil) I, pesticide vapor traps J, flow meter. Reproduced with permission from Ref. 18. Copyright 1983, Pergamon Press.

A simple environmental chamber is quite useful for obtaining volatilization data for model soil and water disposal systems. It was found that volatilization of low solubility pesticides occurred to a greater extent from water than from soil, and could be a major route of loss of some pesticides from evaporation ponds. Henry s law constants in the range studied gave good estimations of relative volatilization rates from water. Absolute volatilization rates from water could be predicted from measured water loss rates or from simple wind speed measurements. The EXAMS computer code was able to estimate volatilization from water, water-soil, and wet soil systems. Because of its ability to calculate volatilization from wind speed measurements, it has the potential of being applied to full-scale evaporation ponds and soil pits. 

Most microarray printers are now housed in boxes set up to control humidity and many are provided with high efficiency particulate air (HEFA) filtration to remove particulates. However, a word of caution attempting to nm a HEFA filter along with a humidifier may be counter-productive if the humid air is exhausted by the HEFA system. Check the design of the environmental chamber to verify whether both devices can be used during a print nm. 

The greenhouse methods used to evaluate our compounds are similar to those used by most companies. Generally candidate fungicides are (1) applied to the foliage of test plants, and (2) allowed to dry for varying periods of time. Test plants are (1) inoculated with the appropriate pathogen, (2) placed in environmental chambers for expression fo disease symptoms or signs and (3) evaluated. 

Tensile Modulus. Tensile samples were cut from the 0.125 in. plates of the compositions according to Standard ASTM D638-68, into the dogbone shape. Samples were tested on an Instron table model TM-S 1130 with environmental chamber. Samples were tested at temperatures of -30°C, 0°C. 22°C, 50°C, 80°C, 100°C and 130°C. Samples were held at test temperature for 20 minutes, clamped into the Instron grips and tested at a strain rate of 0.02 in./min. until failure. The elastic modulus was determined by ASTM D638-68. Second order polynomial equations were fitted to the data to obtain the elastic modulus as a function of temperature for each of the compositions. 

Kerr HD et al Effects of nitrogen dioxide on pulmonary function in human subjects An environmental chamber study. Environ Res 19 392-404, 1979... 

Sensitization of the respiratory tract has followed chronic exposure to fumes or dust of TETA, manifested by bronchial asthma. One worker developed asthma after working with an epoxy resin-TETA formulation for 6 months in a job laminating aircraft windows. In an environmental chamber, the worker developed flulike symptoms and asthmatic breathing after simulating the job conditions for 2 hours with the resin-TETA mixture. Similar exposure to the resin alone did not produce the symptoms. 

At least six major phytotoxic air pollutants have been shown to reversibly inhibit apparent photosynthetic rates in plants (1 - ). Studies indicate that these phytotoxicants ranked in the following order according to the relative amount of inhibition effected after several hours of exposure to equal pollutant concentrations HF>Cl2-03>S02>N02>N0. A summary of the experimental results which compares measured depressions in CO2 uptake rates of barley and oat canopies after 2-hr pollutant exposures in environmental chambers appears in Figure Typical inhibition and recovery rate curves for exposures that reduced CO2 absorption rates by 20 percent at the end of the 2-hr fumigations are also shown. Similar data have been obtained for alfalfa, another important crop species which was cultured and exposed under identical conditions In contrast, equivalent... 

BENNETT AND HILL Inhibition of Photosynthesis Table I. Environmental chamber conditions... 

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