Screen, protective

Ozone, known for its beneficial role as a protective screen against ultraviolet radiation in the stratosphere, is a major pollutant at low altitudes (from 0 to 2000 m) affecting plants, animals and human beings. Ozone can be formed by a succession of photochemical reactions that preferentially involve hydrocarbons and nitrogen oxides emitted by the different combustion systems such as engines and furnaces. 

Depletion of the Ozone Layer. As a constituent of the atmosphere, ozone forms a protective screen by absorbing radiation of wavelengths between 200 and 300 nm, which can damage DNA and be harmful to life. Consequently, a decrease in the stratospheric ozone concentration results in an increase in the uv radiation reaching the earth s surfaces, thus adversely affecting the climate as well as plant and animal life. Pot example, the incidence of skin cancer is related to the amount of exposure to uv radiation. 

OZONE LAYER A thin layer of ozone that lies about 25 kilometres above the earth in the stratosphere. Forms a protective screen against harmful radiation by filtering out ultra-violet rays from the sun. 

Strahlen-pilz, m. actinomyces. -schutz, m. protection from radiation, protective screen, -sonne, /. Biol.) astrosphere. -stein, m. = Strahlstein. -werfen, n. radiation. 

Usage The PC access should be limited to the authorized personnel only. The PC should be used for the conduct of the trial only. The PC should not be left on while unattended. The PC should be covered with the protective cover when idle. We recommend the use of a password-protected screen saver. 

Any problems in the setup, startup, and operation of the CBMS also were recorded in the course of the field tests. These observations are important to improving the system before it goes into production. The field tests revealed three problems. The protective screens over electronics cooling air inlets and outlets on the CBMS II housing were damaged by operator activities in the vehicles and required reinforcement. The ground probe head, which protrudes outside the vehicle hull, required more power to maintain the correct temperature under colder or wetter weather conditions. Finally the automated mass and frequency calibration procedure was not reliable in the field and required modification. These problems have been corrected and are being incorporated in the LRIP units. 

Caution The reactions should he carried out in a hood behind a protective screen since trichloramine is noxious and potentially explosive however, no difficulties from decomposition have been encountered under the conditions described. 

Caution M work is to be undertaken behind a protective screen hands should also be protected with safety gloves in order to avoid cuts should one of the flasks explode (internal pressure 3 bar). 

For further details of the distillation apparatus [see Smith JACS IS 184 7955]. HIGHLY EXPLOSIVE, a strong protective screen should he used at all times. 

As a constituent of the atmosphere, ozone forms a protective screen by absorbing radiation of wavelengths between 200 and 300 nm, which can... 

The National Food Processors Association (NFPA) maintains a database on processed foods, or foods ready to eat. As described by Elkins et al. (1998), NFPA s Protective Screen Program was developed in 1960 and has been used to prevent illegal or unnecessary residues in processed foods. Four triazines have been included in the NFPA monitoring program atrazine, cyanazine, simazine, and ametryn. Through 1997, the NFPA database contained 6563 analyses for these four herbicides, and only 2 detects were found. One positive detect was observed for simazine in com at 0.04 ppm, and one atrazine detect was observed in wheat at 0.05 ppm. Both were well within the tolerance for these compounds in their respective commodities. This industry monitoring indicates that anticipated residues in processed foods are well below existing tolerances for both compounds. 

Propionic acid, /3,/3 -methylimino-bis-, diethyl ester, 20, 35 Propionic anhydride, 21, 14 Protective screen, 22, 97 Pyridine, 20, 50 21, 89 anhydrous, 22, 56... 

Caution Hydrazine is toxic and should be handled in a hood. Anhydrous hydrazine is extremely reactive with oxidizing agents (including air) and should always be prepared and used behind a protective screen. 

A mixture of 112 g. (1.0 mole) of acetone azine and 32 g. (1.0 mole) of anhydrous hydrazine is placed in a 300-ml. round-bottomed flask fitted with a reflux air condenser and drying tube, and kept at 100° for 12-16 hours. (Caution This reaction and the subsequent distillation should be carried out behind a protective screen.) The crude product is then rapidly distilled through a water-cooled condenser and the colorless fraction boiling at 122-126° collected, n22D 1.4607 (Note 7). It weighs 111-127 g. (77-88%, Notes 7 and 8) and is essentially pure acetone hydra-zone (Note 9). 

Caution 2-Diazopropane is volatile and presumably toxic. All operations should be carried out in an efficient hood behind a protective screen. 

When more than one type of work is done in the same room especially handling loose compositions place a protective screen between the work areas ... 

BSC The BSC should operate continuously to ensure containment of hazardous substances. All work-zone interior surfaces with the exception of the HEPA filter-protective screen should be cleaned and sanitized carefully in the manner of the LFCB in the proper order to ensure protection of operator s garb from contaminants and cleaning residues during the cleaning process. This sequence will also prevent the transfer of drug residues to the general environment. " ... 

Cleaning and Preparation. LFCB The LFCB should be allowed to run for at least 30 min before the commencement of aseptic operations. All work-zone accessible surfaces, with the exception of the filter-protective screen, should be cleaned and sanitized by application and recovery of a low-residuing, water-base disinfectant cleanser (household bleach or other hypochlorite solutions should not be used at any time... 

---