Direct and indirect

Rettner C T and Auerbach D J 1994 Distinguishing the direct and indirect products of a gas-surface reaction Science 263 365... 

In resolving complex metal-ion mixtures, more than one masking or demasking process may be utilized with various aliquots of the sample solution, or applied simultaneously or stepwise with a single aliquot. In favorable cases, even four or five metals can be determined in a mixture by the application of direct and indirect masking processes. Of course, not all components of the mixture need be determined by chelometric titrations. For example, redox titrimetry may be applied to the determination of one or more of the metals present. 

Direct and Indirect Energy Gap. The radiative recombination rate is dramatically affected by the nature of the energy gap, E, of the semiconductor. The energy gap is defined as the difference in energy between the minimum of the conduction band and the maximum of the valence band in momentum, k, space. Eor almost all semiconductors, the maximum of the valence band occurs where holes have zero momentum, k = 0. Direct semiconductors possess a conduction band minimum at the same location, k = O T point, where electrons also have zero momentum as shown in Eigure la. Thus radiative transitions that occur in direct semiconductors satisfy the law of conservation of momentum. 

In many semiconductors employed for LEDs, and especially in mixed alloys, the direct and indirect minima ate separated by smaller energies than those of the purely direct and indirect semiconductors. As a result, finite electron concentrations exist within both minima. The total electron concentration, n, is given by equation 5 ... 

Semiconductors can be divided into two groups direct and indirect band gap materials. In direct semiconductors the minimum energy in the conduction band and the maximum in the valence band occur for the same value of the electron momentum. This is not the case in indirect materials. The difference has profound consequences for the transitions of electrons across the band gap in which light is emitted, the radiative transitions, of interest here. 

Models for transport distinguish between the unsaturated zone and the saturated zone, that below the water table. There the underground water moves slowly through the sod or rock according to porosity and gradient, or the extent of fractures. A retardation effect slows the motion of contaminant by large factors in the case of heavy metals. For low level waste, a variety of dose calculations are made for direct and indirect human body uptake of water. Performance assessment methodology is described in Reference 22. 

Ha.logena.tlon, One review provides detailed discussion of direct and indirect methods for both mono- and polyhalogenation (20). As with nitration, halogenation under acidic conditions favors reaction in the benzenoid ring, whereas reaction at the 3-position takes place in the neutral molecule. Radical reactions in the pyridine ring can be important under more vigorous conditions. 

Rosin has a low order of toxicity foUowing ingestion or skin contact. Rosin and its numerous derivatives have a number of permitted food packaging and other direct and indirect food contact uses throughout the world. Sanctioned uses appHcable in the United States are outlined in U.S. Food and Dmg Administration (U.S. FDA) Regulations (2). Material Safety Data Sheets (MSDSs) for specific rosins and thein derivatives should be consulted before thein use. 

Electric-Arc Furnace. The electric-arc furnace is by far the most popular electric steelmaking furnace. The carbon arc was discovered by Sir Humphry Davy in 1800, but it had no practical appHcation in steelmaking until Sir William Siemens of open-hearth fame constmcted, operated, and patented furnaces operating on both direct- and indirect-arc principles in 1878. At that early date, the avadabiHty of electric power was limited and very expensive. Furthermore, carbon electrodes of the quaHty to carry sufficient current for steel melting had not been developed (see Furnaces, electric). 

V accine Direct medical savings, Direct and indirect savings, ... 

At the current stage of development, direct and indirect liquefaction technologies loc equally attractive economically, and botn have the potential for significant cost improvements. 

Judicious use of chemical inhibitors or cathodic protection may directly and indirectly reduce crevice attack. However, if conditions are very severe, economics may make such applications impractical. 

Deposits cause corrosion both directly and indirectly. If deposits contain corrosive substances, attack is direct interaction with the aggressive deposit causes wastage. Shielding of surfaces below deposits produces indirect attack corrosion occurs as a consequence of surface shielding provided by the deposit. Both direct and indirect attack may involve concentration cell corrosion, but indirect attack almost always involves this form of corrosion. 

Golde, R.H., Lightning surges on overhead disiribuii(m lines caused by direct and indirect lightning strikes. AIEE Transactions (Power Apparatus and Systemi. 437-447. June (1959) IRC. 56-HV AC Circuit Breakers. 

Most producers believe in the adage quality pays in terms of better reputation and sales, customer loyalty, lower reject rates, service and warranty costs. They should also realize that safety pays in terms of reducing the legal exposure and the tremendous costs that this can incur, both directly and indirectly, for example from compensation, legal fees, time and effort, increased insurance premiums, recalls and publicity (Wright, 1989). Few manufacturers understand all the cost factors involved, and many take a shortsighted view of the actual situation with regard to the costs of safety. 

Each permit issued to a facility will be for a fixed term of up to 5 years. The new law establishes a permit fee whereby the state collects a fee from the permitted facility to cover reasonable direct and indirect costs of the permitting program. 

Bojnowski, J. J., Groghan, R. M., Jr., and Hoffman, R. M., Direct and Indirect Material Balance Control, Chemical Engineering Progress, September 1976. 

Daley, M. A., Tandon, D., Economy, J. and Hippo, E. J., Elucidating the porous structure of activated carbon fibers using direct and indirect methods. Carbon, 1996,34(10), 1191 1200. 

Tier 0 and Tier 1 costs are direct and indirect costs. They include the engineering, materials, labor, construction, contingency, etc., as well as waste-collection and transportation services (in many cases we simply transform an air pollution problem into a solid waste or wastewater problem that requires final treatment and disposal), raw-material consumption (increase or decrease), and production costs. Tier 2 and... 

These are addressed ind The Backfit Rule (10 CFR 50.109, and the NRC Safety Goal Policy Statement (SECY-89-102). The Backfit Rule applies not to the regulated industry, but to the NRC staff. It says that backfitting is required if it will result in substantial increase in safely and the direct and indirect costs of backfitting are justified. (This limitation does not apply if the modification is necessary for compliance with regulations). 

Different available measurement instruments and evaluation methods are described in Chapter 12. Some specific methods to evaluate local ventilation systems are described in this section. All local ventilation systems should be evaluated regularly. The evaluation procedures can be divided into detailed and simple, as well as direct and indirect, procedures. The detailed procedures need special instruments and competence, whereas it should be possible to use the simple procedures every day. Since the simple procedures do not measure directly the performance of the exhaust, it is usually necessary to calibrate a simple procedure by using a detailed procedure. ... 

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