Primary and secondary processes

Fig. 26. Schematic diagram of akraft recovery boiler, where ( " ) indicates primary and (-) secondary process streams (29).

Cole, P. M. Sole, K. C. Solvent extraction in the primary and secondary processing of zinc. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 863-870. 

The process responsible for taking care of the resources is called the secondary process. Examples are maintenance or internal transportation, and the personnel department, material purchase, etc. Finally there is a tertiary process present in an organization, that directs and co-ordinates the primary and secondary processes, and their relationship with each other and the environment. 

Chondrites are the oldest and most primitive rocks in the solar system. They are hosts for interstellar grains that predate solar system formation. Most chondrites have experienced a complex history, which includes primary formation processes and secondary processes that inclnde thermal metamorphism and aqneons alteration. It is generally very difficult to distinguish between the effects of primary and secondary processes on the basis of isotope composition. Chondrites display a wide diversity of isotopic compositions including large variations in oxygen isotopes. 

When this pressure drops, it can be built-up again by water flooding. Unfortunately, after these primary and secondary processes, there still remains up to 70% of the oil adsorbed on the porous clays. Consequently, in recent years, there have been tremendous efforts made to develop tertiary oil recovery processes, namely carbon dioxide injection, steam flooding, surfactant flooding and the use of microemulsions. In this latter technique, illustrated in Fig. 1, the aim is to dissolve the oil into the microemulsion, then to displace this slug with a polymer solution, used for mobility control, and finally to recover the oil by water injection ( 1). 

In addition to knowing the temperature shift factors, it is also necessary to know the actual value of ( t ) at some temperature. Dielectric relaxation studies often have the advantage that a frequency of maximum loss can be determined for both the primary and secondary process at the same temperature because e" can be measured over at least 10 decades. For PEMA there is not enough dielectric relaxation strength associated with the a process and the fi process has a maximum too near in frequency to accurately resolve both processes. Only a very broad peak is observed near Tg. Studies of the frequency dependence of the shear modulus in the rubbery state could be carried out, but there... 

The quantum yield of a primary photochemical process must be a number between 0 and 1, since it represents the probability that the excited state will undergo the reaction. The quantum yield of overall (that is, primary and secondary) processes can on the other hand be greater than 1, depending on the secondary reactions it can be very large in the case of chain reactions. 

The temperature dependence of spectral sensitization can vary with the dye used, its state of aggregation, the emulsion used, and the gaseous environment at the time of exposure (277). The apparent activation energy, as calculated from the temperature dependence data, could be the resultant of both primary and secondary processes unless conditions were such that the secondary processes were temperature independent. 

Time Scale of Primary and Secondary Processes at Different Radiolysis Stages... 

Similar to the epoch of classical ideas, coherent synchronous reactions are divided into primary and secondary processes the primary reaction synthesizes reactive intermediates promoting bifurcation—the process splitting to, at least, two reaction flows. One of the flows is the continuation of the primary reaction, and another is responsible for the secondary reaction proceeding. Thus, the reaction system operates in the bifurcation regime— synchronous reaction interaction (coherence). 

Table 1. Tunneling distances R[ and RJyp for primary and secondary processes of PET reactions calculated using Eq. (2) with v = 102° s- a = 2.5 A (Rf ) and ve = 1015 s ae = t A (R >1 ) for various values of time t. For primary processes the values t = x = 10-9 — 1 s can be taken as typical while for secondary processes all the values t = xs are possible...

The following regularities of electron tunneling in primary and secondary processes of PET can be mentioned. 

This contribution gives a review of recent spectroscopic investigations concerning the photophysical and photochemical primary and secondary processes of the solid state polymerization reaction in diacetylene single crystals. It will be shown, that diacetylenes are an unique model system for the study of the reaction mechanism of a solid state chemical reaction which is characterized by a variety of reaction intermediates. The polymerization reaction in these crystals is of special importance, due to the resulting polymer single crystals, which exhibit extraordinary anisotropic physical properties. 

In all experiments described in this work only extremely low concentrations of intermediates are considered. This is due to our interest which is primarily focussed on the most important initial steps of the polymerization reaction, which are characteristic of the overall polymerization reaction mechanism. Consequently only low final polymer conversion is exp>ected and, therefore, complications arising from the interaction between the intermediate oligomer states can be neglected. It will be shown that the low temperature conventional optical absorption and ESR spectroscopy are powerful spectroscopic methods which yield a wealth of information concerning structural and dynamical aspects of the intermediate states in the photopolymerization reaction of diacetylene crystals. Therefore, this contribution will center on the photochemical and photophysical primary and secondary processes of this... 

In this article it has been shown, that the low temperature photopolymerization reaction of diacetylene crystals is a highly complex reaction with a manifold of different reaction intermediates. Moreover, the diacetylene crystals represent a class of material which play a unique role within the usual polymerization reactions conventionally performed in the fluid phase. The spectroscopic interest of this contribution has been focussed mainly on the electronic properties of the different intermediates, such as butatriene or acetylene chain structure, diradical or carbene electron spin distributions and spin multiplicities. The elementary chemical reactions within all the individual steps of the polymerization reaction have been successfully investigated by the methods of solid state spectroscopy. Moreover we have been able to analyze the physical and chemical primary and secondary processes of the photochemical and thermal polymerization reaction in diacetylene crystals. This success has been largely due to the stability of the intermediates at low temperatures and to the high informational yield of optical and ESR spectroscopy in crystalline systems. 

Reviews have appeared of the photophysics of molybdenum complexes, primary and secondary processes in organometallic chemistry, flash photolysis of Pe(CO)5 and Cr(CO)g, dinuclear manganese carbonyl compounds, the photochemistry of metal complexes isolated in low temperature matrices, cluster complexes, diene complexes, photoproduction of coordinativeiy unsaturated species containing rhodium or iridium, and redox chemiluminescence of organometallic compounds.Synthetic and metal organic photochemistry in industry has also been reviewed. 

When ions and excited molecules have been formed in this manner, a variety of secondary processes may occur before the final chemical change takes place. To illustrate the nature of such primary and secondary processes, the behavior of water on exposure to ionizing radiations will be considered this is a matter of fundamental importance in the present review, because the majority of carbohydrate investigations in this field have been undertaken in aqueous solution. 

In view of these solvent structure effects, it is convenient to classify the recombination events into primary and secondary processes. Primary recombination processes are those in which the recombination takes place before the atoms separate to a distance roughly equal to the first maximum in the mean potential (i.e., recombination in the solvent cage ). Secondary recombination involves the recombination of solvent-separated-atom pairs. 

Secondary emission is any process that releases new airborne contaminants from existing sources, changes the total emittable mass of existing contaminants, or results in chemical reactions between compounds on surfaces and in the air. Secondary emission may be based on sorption, oxidation, hydrolysis, decomposition or other chemical reactions in or on a source or the indoor air. A secondary emission process is often highly influenced by past and present environmental conditions. It is not always possible to tell if a compound found in the air is there because of a primary or secondary emission process since a source may emit the same compound by both primary and secondary processes. Purposely added materials such as cleaning products may be a primary emission source, but reactions between constituents of new and existing products may cause a secondary emission process. 

That the radiolysis of meats containing similar proteins and comparable fatty acids involves similar primary and secondary processes leading to a common set of radicals stable at -40°C is shown by the ESR spectra in Figure 12 for irradiated, enzyme-inactivated chicken, beef, ham, and pork [3, 62], These spectra reflect the commonality in radicals derived from the muscle proteins, myosin and actin, and fi-om the constituent triglycerides, which have slightly different fatty acid compositions. The minor consequences of this compositional... 

The overall quantum yield (Overall Q.Y.) is defined as the ratio of the total number of pollutant molecules degraded via primary and secondary processes over the total number of photons absorbed (Cassano et al., 1995). This overall quantum yield can, in principle, be greater than 100% (Cassano et al., 1995). This fact puts forwai d interesting prospects for photocatalytic processes. 

The field of aquatic photochemistry encompasses a wide diversity of areas within environmental science. Natural waters receiving solar radiation are active photochemical reactors. Within these reactors, primary and secondary processes are occurring. Heterogeneous reactions are associated with both living and nonliving particulate matter. Naturally occurring humic substances are relatively efficient initiators of photochemical reactions. Many xenobiotic chemicals in natural waters undergo either direct or indirect photochemical transformations. 

Cu(I) formation observed here Is probably the result of a combination of primary and secondary processes. Primary processes may be Important In destroying Cu(II) complexes which are Inert to secondary reactions, thereby making secondary processes more Important. The decay of Cu(I) after Irradiation Is much slower than the expected, since Its half life In the presence of 0. Is under 6 minutes. Therefore, the presence of relatively long lived reductant species such as must be Invoked. Artificial seawater containing ultrafiltrate also produced Cu(I) upon solar Irradiation, but chloride free media did not ( ), In agreement with kinetic expectations based on the extremely rapid oxidation of Cud) In chloride free media. 

Primary and secondary processes contribute to the cost of a finished component. 

The main task in the monitoring of radionuclides in fission products (nuclides produced by primary and secondary processes associated with fission, generally of the uranium isotopes and U), transuranium nuclides, and transplutonium elements is the identification of nuclides and the determination of yield. A... 

Both the primary and secondary processes produce a material called sludge, which is a mixture of particulate matter and living and dead microorganisms. The sludge is dried and disposed of by incineration or in a landfill. It can even be spread on certain types of cropland, where it acts as a fertilizer. 

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