Concentration development

The example being considered under zinc ore pertains to acid pressure leaching of zinc concentrates developed by Sherritt Gordon Mines Ltd. in Canada. The basic reaction involved is... 

Acceptable daily intake for 70-kg person (with a safety factor of 1000) Concentrations developed for noncarcinogenic effects 0.031 mg daily (equivalent to 0.443 pg/kg BW daily) 6... 

Hycon (2) A process for making nitric acid which can provide a range of concentrations. Developed in 1968 by the Chemical Construction Corporation. 

Teijin A process for oxidizing / -xylene to terephthalic acid. The catalyst used is a soluble cobalt compound, used at a high concentration. Developed by Teijin, Tokyo. 

Figure 2 shows the exposure characteristics for azide-styrene resin resist film with an azide concentration from 10 to 40 wt% (based on the styrene resin weight) and Figure 3 shows the contrast of the resist films as a function of the azide concentration. Development was done with a 60s immersion in 0.83% TMAH solution. The styrene resin matrix alone has been found to be a negative deep UV resist. However, rather low contrast (1.48) and low sensitivity (2.5 J/cm2) are observed. The contrast and the sensitivity of the styrene resin is remarkedly increased by adding the azide, as shown in Figures 2 and 3. 

Figure 8 shows the effect of the alkaline concentration in TMAH solutions on the contrast and sensitivity of the new resist. Sensitivity of the resist increases as the alkaline concentration increases, however, the contrast is maxima (4.72) at 0.83% TMAH solution. This means that the higher concentration over 0.83% cannot distinguish the difference of the dissolution rate between the unexposed and exposed resist film. For instance, the higher concentrated developer also attacks the exposed areas and the loss of resist thickness occurs. The alkaline concentration in TMAH solution, therefore, is optimized at 0.83%. This developer concentration was subjected to the following lithographic evaluation. 

Table i Characteristics of Pre-concentrators developed at SNL. The effect of reducing the size of the pre-concentration is seen in reduced concentration factor... 

Workers exposed to unspecified concentrations developed slight irritation of the eyes and respiratory tract. Systemic effects have not been reported from industrial exposure. 

The UFP emission rate of a laser printer cannot be determined using the same techniques as for the (S)VOC case. Here, the superposition of particle release and deposition has to be solved mathematically. Using this method, different types of emitting behavior ( constant emitter or initial-burst emitter ) can be identified for the printer under observation (Schripp et al, 2008). It was mentioned above that the determination of the emission rate of a VOC allows the calculation of the air concentration in a model room. For particulate emissions this is not the case. If the deposition in the room is unknown an estimation of the particle concentration development is not possible even though the emission rate of the printer is known (Wensing et al, 2008). 

Table VI shows the concentrations of plutonium, neptunium, and uranium measured at the inlet and outlet of the unaltered and hydrothermally-altered basalt core fissures in the first five analog experiments (see Table I) Under conditions simulating a repository that was unaltered by groundwater interaction (Table I, Exp 1-3), both Np and Pu, in the concentrations developed in these analog experiments from the leaching of the waste form, were substantially retarded within the 14.6-cm basalt fissure In fact, as can be seen from Figure 4, almost all of Np activity was sorbed on the first one-third of the rock fissure The data in Figure 4 have an estimated error, based on counting statistics above, of approximately 2 counts per 1000 seconds Uranium retardation was determined to be not as complete ...

With the award of the LEAA educational development grant in July 1973, the decision was rapidly reached between personnel in the College of Criminal Justice and the Department of Chemistry to concentrate development in the area of forensic science. This decision was based on the strengths in the College of Criminal Justice, the Department of Chemistry (especially in chemical analysis and materials science) and the considerations outlined... 

Sodium bisulfite is often preferred in pyro developers and in Phenidone concentrates (Appendix 3 Pharmacopoeia Phenidone). Sodium bisulfite3 is often used in formulas that are divided into two solutions, as its weak acidity helps to inhibit the oxidation of the concentrated developing agent. When carbonate, contained in the B solution, is added to make a working solution, the bisulfite is immediately broken down into sulfite and bicarbonate, producing a useful buffering effect. 

Uses As a preservative in photographic emulsions concentrated developers rapid drying and cleaning. 

Both calculations and measurements have indicated that it is possible to develop very concentrated metal chloride solutions within occluded sites. For example, stainless steel pits would be expected to contain 5 N Cl", 4 N Fe2+, 1 N Cr3+, 0.5 Ni2+, and 0.007 N Na+ and have a pFl of 0.5. The low sodium ion concentration develops as the Na+ migrates out of the crevice due to the electric field but is not replaced by any reaction in the crevice. Recent measurements (24) of active crevice sites on Type 316L stainless steel showed the following concentrations 2.9M Fe2+, 0.77 M Cr3+, 0.24 M Ni2+, and 0.06 M Mn2+. As was stated above, stainless steel will not remain passive in such a solution and can dissolve at a high rate. The autocatalytic nature of the process stabilizes the environment by exceeding the rate at which diffusion can disperse the concentrated solution. Initial dissolution rates of the order of 1 A/cm2 ( 440 in./yr) can be reached. 

Plasmas typical of C02 laser discharges operate over a pressure range from 1 Torr to several atmospheres with degrees of ionization, that is, nJN (the ratio of electron density to neutral density) in the range from 10-8 to 10-8. Under these conditions the electron energy distribution function is highly non-Maxwellian. As a consequence it is necessary to solve the Boltzmann transport equation based on a detailed knowledge of the electron collisional channels in order to establish the electron distribution function as a function of the ratio of the electric field to the neutral gas density, E/N, and species concentration. Development of the fundamental techniques for solution of the Boltzmann equation are presented in detail by Shkarofsky, Johnston, and Bachynski [44] and Holstein [45]. 

Numerous formulation are available for all film-forming polymers offered in the market. Thus, it is possible to dispense with many of the preliminary tests and concentrate development work on the special problems of the formulation in question. In this chapter, we will focus on SEPIFILM and Kollidon VA 64. Table 16 presents proven basic formulations reported on in the literature [61] and polymers used for the most important commercially available film formers, which also can be used as a basis for further tablet coating. 

Rothamstead A process for extracting protein from leaves. Green plant juice is coagulated at 70°C, yielding a lipid-protein concentrate. Developed at the eponymous research institute in the United Kingdom. 

A peeling method, in conjunction with a radioactive tracer technique, was used to obtain actual profiles of DOP concentration developed through the matrix of a PVC disc dipped into a limited volume of olive oil. The plasticiser concentration distributions were reproduced to a good approximation using a known model, adjusted by neglecting the (small) amounts of oil which diffused into the polymer. 17 refs. 

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