Chemicals substitutions

It is possible to systematically alter the net magnetic moment of ferrites by chemical substitutions. A very important industrial appHcation is the increase of the magnetic moment in mixed MnZn-ferrites and NiZn-ferrites. When Zn ions are introduced in Mn-ferrite or Ni-ferrite, these ions prefer to occupy A-sites. Because is nonmagnetic, the A-sublattice magnetization is reduced and consequendy the total net magnetic moment is increased. 

L. M. Brown,. Springer, and M. Bower, Chemical Substitution for 1,1,1 -Trichloroethane and Methanol in an Industrial Cleaning Operation, U.S. EPA, Cincinnati, Ohio National Technical Information Service, Springfield, Va., 1992. 

Inherent safety Inventory reduction Fewer chemicals inventoried or fewer in process vessels. Chemical substitution Substitute a less hazardous chemical for one more hazardous. Fr ocess attenuation Use lower temperatures and pressures. 

Information provided in Part III. Section 8. of Form R is optional. In this section, you may identify waste minimization efforts relating to the reported toxic chemical. Waste minimization reduces the amount of the toxic chemicai in wastes by reducing waste generation or by recycling. This can be accomplished by equipment changes, process modifications, product reformulation, chemical substitutions, or other techniques. Waste minimization refers exclusively to practices which prevent the generation of wastes. Treatment or disposal does not minimize waste and should not be reported In this section. Recycling or reuse of a toxic chemical is considered waste minimization. Waste minimization applies to air emissions and wastewater, as well as to liquid or solid mate-... 

We note that chemical substitution of a radical into a basic compound corresponds (in the sense of the main theorem of Chapter 1) to the algebraic substitution of the generating function into the cycle index of the group of the basic compound. 

Exercise 6.2. Chemical substitution experiments have indicated that the presence of the negatively charged Asp 52 changes the pKa of Glu 35 by 1.1 units. Using the distances between Asp 52 and Glu 35 and between Asp 52 and Cj (which are 6.2 and 3.8 A, respectively) and a uniform dielectric constant, estimate the stabilization of C/ by Asp 52. 

First reported by Fredenhagen in 1926 F3, F4), the graphite-alkali-metal compounds possess a relative simplicity with respect to other intercalation compounds. To the physicist, their uncomplicated structure and well defined stoichiometry permit reasonable band-structure calculations to be made S2,12) to the chemist, their identity as solid, "infinite radical-anions frequently allows their useful chemical substitution for such homogeneous, molecular-basis reductants as alkali metal-amines and aromatic radical anions N2, B5). 

A comprehensive theoretical investigation of PECD in a series of substituted oxiranes has been presented by Stener et al. [53] using the B-spline method. Variations in the predicted dichroism were found as both a function of initial orbital, and of the chemical substitution about the epoxy ring. These substitutions do not induce very significant geometry changes in the optimized ring structure. 

In the same CMS-Xa study [52], a series of (/f)-carvone derivatives, all in their single most stable conformation, were examined with a view to determining the influence of chemical substitution on the PECD. Both the... 

In the case of a heterogeneous polymer comprising molecular species differing in size but otherwise equivalent chemically, substitution of Eq. (12) for ASm gives... 

The need to evaluate alternatives often arises once the decision to eliminate chemicals of concern is made. Sometimes a chemical of concern can be eliminated through product design such as through the use of a material that is inherently flame retardant or a fabric barrier without the need for added flame-retardant chemicals. But when the only currently feasible option appears to be a chemical substitution, then the alternatives must be evaluated and assessed to ensure that they are in fact greener than the chemical they are intended to replace. We provide as examples of implementing alternatives assessment, the Green Screen for Safer Chemicals and the DfE Flame Retardants in Printed Circuit Boards Partnership. 

Table 4 Influence of Chemical Substitution on the Membrane Permeability of Several Series of Nonelectrolytes... 

Based on a survey of chemical suppliers and electroplaters who use nonpolluting chemicals, some commonly used chemical substitutes are summarized in Table 9.10. 

The recommended treatment option for control of toxic pollutants regulated under PSES categorical standards is chemical substitution. Although chemical substitution of sodium hydrosulfite for zinc hydrosulfite is recommended for control of zinc at groundwood mills, PSES for zinc were calculated using treatment performance data for lime precipitation.39... 

It is often possible to use different process chemicals to accomplish the same goal. For example, both zinc hydrosulfite and sodium hydrosulfite can be used to bleach mechanical pulps. The substitution of the use of sodium hydrosulfite for zinc hydrosulfite was prompted, at least in part, by the establishment of effluent limitations controlling the discharge of zinc. Other opportunities exist to minimize the discharge of toxic and nonconventional pollutants through chemical substitution. 

Reducing smelting furnaces that produce a high-sulfidity, kraft-like green liquor are now employed at sodium-based sulfite mills. U.S. EPA anticipates that it would be necessary to replace the existing recovery boilers at ammonia-based mills if chemical substitution to a sodium base were employed. Additionally, it is likely that, because the heat value of sodium spent liquor is lower than ammonia spent liquor, evaporator modification may he required if excess capacity does not already exist. 

Chemical substitution in a pattern that breaks the 2v symmetry of the molecular frame introduces a threefold component to the one-dimensional model torsional potential ... 

Lichtenberger DL, Johnston RL, Hinkelmann K, Suzuki T, Wudl F (1990) Relative electron donor strengths of tetrathiafulvene derivatives effects of chemical substitutions and the molecular environment from a combined photoelectron and electrochemical study. J Am Chem Soc 112 3302-3307... 

The effect of isotopic or chemical substitutions on the vibrational frequency leads to the identification of the species that comprise a defect complex. For example, the large frequency shift that results upon the substitution of D for H leads to an unambiguous identification of the H motions. For a series of chemically similar complexes, such as the acceptor-H complexes, the frequency shifts that occur for group III substitutions show that the acceptor is indeed involved in the complex. 

---