Short term

Short-term exposure. This is the maximum concentration to which workers can be exposed for a period of up to 15 minutes continuously without suffering from (a) intolerable irritation, (b) chronic or irreversible tissue change, or (c) narcosis of sufficient degree to increase accident proneness, impair self-rescue, or materially reduce efficiency, provided that no more than four excursions per day are permitted, with at least 60 minutes between exposure periods, and provided the daily time-weighted value is not exceeded. 

Short-term, 250-p.m-thick sample. AsTM method D257. 

Short-term (100 h) internal pressure creep mpture testsof small bore cylinders having diameter ratios of 3 to 4, made of a number of different refractory metals, have been investigated at temperatures in the range 900—1300°C (73). 

For short term simulations, accuracy requirements on the discrete solution make sense and we advocate error controlling adaptive integrators. Moreover, we have to further subdivide our classification due to the observations in Sec. 2.2  

Guide for Short Term Exposures of the Public to Mir Pollutants, Guidefor Hydra ne, Monomethylhydra ne and 1,1 -Dimethylhydra ne, Committee on Toxicology of the National Academy of Science, National Research Council, Washington, D.C., Jan., 1975. 

At least in the short term, European production is expected to be impacted by two trends the move away from planned economics in the East should lead to more rapid demand growth and the phaseout of CPCs, including, in Europe, aerosols (qv), should lead to overcapacity in the West. This excess capacity in western Europe could be used to supply the East. 

Hence, as the second class of techniques, we discuss adaptive methods for accurate short-term integration (Sec. 4). For this class, it is the major requirement that the discretization allows for the stepsize to adapt to the classical motion and the coupling between the classical and the quantum mechanical subsystem. This means, that we are interested in discretization schemes which avoid stepsize restrictions due to the fast oscillations in the quantum part. We can meet this requirement by applying techniques recently developed for evaluating matrix exponentials iteratively [12]. This approach yields an adaptive Verlet-based exponential integrator for QCMD. 

If a Tg value corresponding to a true second-order transition exists, it is a value lower than those based on short-term observations. The latter should then be regarded as approximations to the true value. 

Molten ETFE polymers corrode most metals, and special corrosion-resistant alloys ate recommended for long-term processiag equipmeat short-term prototype mas are possible ia standard equipment. 

The successflil appHcation of time—temperature superposition (159) for polystyrene foam is particularly significant in that it allows prediction of long-term behavior from short-term measurements. This is of interest in building and constmction appHcations. 

Summarizing, from a mathematical point of view, both forward and backward analysis lead to the insight that long term trajectory simulation should be avoided even with symplectic discretizations. Rather, in the spirit of multiple as opposed to single shooting (cf. Bulirsch [4, 18]), only short term trajectories should be used to obtain reliable information. 

North American HF production capacity has declined since the early 1980s and several smaller producers, such as Harshaw and Essex, have closed plants. Production is expected to continue to decline in the short term because of chlorofluorocarbon (CPC) cutbacks, but is expected to rebound later in the 1990s as replacement hydrochlorofluorocarbons are introduced to the marketplace. 

The 2-cyanoacryhc esters have sharp, pungent odors and are lacrimators, even at very low concentrations. These esters can be irritating to the nose and throat at concentrations as low as 3 ppm eye irritation is observed at levels of 5 ppm (13). The TLV for methyl 2-cyanoacrylate is 2 ppm and the short-term exposure limit is 4 ppm (14). Good ventilation when using the adhesives is essential. 

Creep. The creep characteristic of plastic foams must be considered when they are used in stmctural appHcations. Creep is the change in dimensions of a material when it is maintained under a constant stress. Data on the deformation of polystyrene foam under various static loads have been compiled (158). There are two types of creep in this material short-term and long-term. Short-term creep exists in foams at all stress levels however, a threshold stress level exists below which there is no detectable long-term creep. The minimum load required to cause long-term creep in molded polystyrene foam varies with density ranging from 50 kPa (7.3 psi) for foam density 16 kg/m (1 lb /ft ) to 455 kPa (66 psi) at foam density 160 kg/m (10 

Tests with animals have revealed that dioxin is one of the most toxic substances known Toward mice it IS about 2000 times more toxic than strychnine and about 150 000 times more toxic than sodium cyanide Fortunately however available evidence in dicates that humans are far more resistant to dioxin than are test animals and so far there have been no human fatalities directly attributable to dioxin The most prominent short term symptom seen so far has been a severe skin disorder known as chloracne Yet to be determined is the answer to the question of 

The purpose of chemical processes is not to make chemicals The purpose is to make money. However, the profit must he made as part of a sustainable industrial activity which retains the capacity of ecosystems to support industrial activity and life. This means that process waste must be taken to its practical and economic minimum. Relying on methods of waste treatment is usually not adequate, since waste treatment processes tend not so much to solve the waste problem but simply to move it from one place to another. Sustainable industrial activity also means that energy consumption must be taken to its practical and economic minimum. Chemical processes also must not present significant short-term or long-term hazards, either to the operating personnel or to the community. 

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