Emission direct

Methanol substitution strategies do not appear to cause an increase in exposure to ambient formaldehyde even though the direct emissions of formaldehyde have been somewhat higher than those of comparable gasoline cars. Most ambient formaldehyde is in fact secondary formaldehyde formed by photochemical reactions of hydrocarbons emitted from gasoline vehicles and other sources. The effects of slightly higher direct formaldehyde emissions from methanol cars are offset by reduced hydrocarbon emissions (68). 

X-Ray Emission and Fluorescence. X-ray analysis by direct emission foUowing electron excitation is of Hmited usefulness because of inconveniences in making the sample the anode of an x-ray tube. An important exception is the x-ray microphobe (275), in which an electron beam focused to - 1 fim diameter excites characteristic x-rays from a small sample area. Surface corrosion, grain boundaries, and inclusions in alloys can be studied with detectabiHty Hmits of -- 10 g (see Surface and interface analysis). 

There are four methods dial can be used to delcrmine a chemical health hazard. These methods are emission factors, mass baliuice considerations, engineering calculations, and direct emission measnrenienls. Describe each of diese approaches. 

Direct emission measurements involve the direct measurement of emission rates from specific sources. Direct emission measurements provide tlie data for emission factor and engineering calculations. This is tlie only method tliat provides emission rates for a given source for a given set of conditions. 

Major advances into geometries that are potential candidates for an electrically driven lasing device with a highly directional emission were then reported independently by three different groups [37-39]. It is worthwhile to note that the submission dates of the first three papers on this subject differ by less than two months. 

Particles are emitted Into the atmosphere from numerous natural and manmade sources and are also formed upon condensation of gases and vapors. Direct emissions of Suspended Particulate Natter (SPN) arise from a variety of human activities Including combustion. Industrial and agricultural practices the remainder Is formed from gas-particle conversions (chiefly from SOj oxidation to sulfuric acid as sulfate salts). Particles larger than about lOpm In diameter deposit In the vicinity of the sources, but smaller... 

An additional area of concern with respect to stratospheric ozone is possible direct emissions of NOj into the stratosphere by high-flying supersonic aircraft. This issue has come up repeatedly over the past 20 years, as air travel and pressure from commercial airlines has increased. However, despite substantial research effort to understand stratospheric chemistry, the question is complicated by the changing levels of stratospheric chlorine, first due to a rapid accumulation of tropospheric CFCs, followed by a rapid decline in CFC emissions due to the Montreal Protocol. To quote from the from the 1994 WMO/UN Scientific assessment of ozone depletion, executive summary (WMO 1995) ... 

Unbumt gasoline and cracked hydrocarbons such as ethylene and propylene are also substantial constituents of exhaust. Gasoline contains additives such as benzene, toluene and branched hydrocarbons to achieve the necessary octane numbers. The direct emission of these volatile compounds, e.g. at gas stations, is a significant source of air pollution. Leaded fuels, containing antiknock additions such as tetra-ethyl-lead, have been abandoned because lead poisons both human beings and the three-way exhaust catalyst, especially for the removal of NO by rhodium. 

Bouwman, A. F. (1996). Direct emission of nitrous oxide from agricultural soils. Nutr. Cycl. Agroecosyst. 46, 53-70. 

The European Commission has also emphasised that CCS may be the only option available to reduce direct emission from industrial processes at the large scale needed in the longer term. ... 

Scope 1 indicates direct emissions, for example, on-site emissions Scope 2 indicates emissions embodied in the purchased energy and Scope 3 indicates all the emissions not covered under Scope 2, such as those associated with transport of goods and waste disposal [12]. 

In the earlier mentioned MFA studies, no direct emission of DEHP from waste incineration or landfill to air or surface water is reported. For incineration it is assumed that DEHP is decomposed into C02 and H20. For landfill it is assumed that DEHP is degraded into C02 and CH4 [26] or enters the waste water, which subsequently is treated in the WWTP [27]. 

Under the applied QWASI model assumptions, the QWASI results are in the range of measured data reported in literature and thus support that the strongest impact to sediment and water concentrations of DeBDE are from direct emission to water as opposed to atmospheric concentrations. This result points out the high importance of DeBDE-leaching from deposited waste material and a lower meaning of the fraction that is transferred to the atmosphere. 

Pb concentration in the environment, on the other hand, is strongly influenced by air concentration and rain rate, in addition to direct emissions to water. For this metal the exposure pathway via burning gains a high importance among the different informal recycling processes. 

Direct emission of fossil C02 by the consumption of energy/auxiliary fuels (i.e., electricity, heat, natural gas/diesel)... 

These energy-transfer processes are especially interesting in those chemiluminescence reactions where the primary electronically excited product is formed in its triplet state (autoxidation reactions, radical-ion recombination reactions see Sections III and VIII), although some reactions have been reported to involve direct emission from the excited triplet state 14>. 

Subsequent to the formation of a potentially chemiluminescent molecule in its lowest excited state, a series of events carries the molecule down to its ground electronic state. Thermal deactivation of the excited molecule causes the molecule to lose vibrational energy by inelastic collisions with the solvent this is known as thermal or vibrational relaxation. Certain molecules may return radia-tionlessly all the way to the ground electronic state in a process called internal conversion. Some molecules cannot return to the ground electronic state by internal conversion or vibrational relaxation. These molecules return to the ground excited state either by the direct emission of ultraviolet or visible radiation (fluorescence), or by intersystem crossing from the lowest excited singlet to the lowest triplet state. 

Molecular cluster ions are highly useful because they reveal which elements are in contact in the sample. Of course, this presupposes that such clusters are emitted intact and are not the result of recombination processes above the surface. Oechsner [12] collected evidence that direct cluster emission processes predominate in cases where relatively strong bonds exist between neighbor atoms. Direct emission be-... 

SIMS spectra of the RhCf salt in Fig. 9.1 show clear molecular peaks characteristic of rhodium coordinated by chlorine. In particular the RhCl2 signal is very intense. As explained in Chapter 4, there is little doubt that molecular cluster ions from compounds other than alloys are the result of a direct emission process. Hence, Fig. 9.1 implies that if a sample contains rhodium atoms with more than one chlorine ligand, SIMS is capable of detecting this combination with high sensitivity. 

The mobility of slowly degradable compounds or persistent metabolites present in surface water or bank filtration-enriched ground water is of particular concern in the production of potable water. Certain surfactants, and especially their polar metabolites among others, have the potential to bypass technical purification units used, which may include flocculation, (active charcoal) filtration, ozonation or chlorination. As such, these compounds can reach drinking water destined for human consumption [4-6]. In most cases the origin of surfactant residues and their degradation intermediates in raw water is from wastewater treatment plant (WWTP) effluents (see Chapters 6.1 and 6.2) or direct emissions of wastewater, with the latter still common in many less developed countries. 

Relatively low Q-factors (850-1500), highly directional emission and high FSR of the bow-tie modes WGM Q-factors lower than in circular microdisks, efficient coupling to planar waveguides... 

Gmachl, C., Cappasso, F., Narimanov, E.E., Nockel, J.U., Stone, A.D., Faist, J., Sivco, D.L., and Cho, A.Y., 1998, High-power directional emission from microlasers with chaotic resonances. Science 280 1556-1564. 

Shima, K., Omori, R., and Suzuki, A., 2001, High- Q concentrated directional emission from egg-shaped asymmetric resonant cavities. Opt Lett. 26(ll) 795-797. 

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