Effect of modifier concentration

Photochemistry in Modified Supercritical Carbon Dioxide—Effect of Modifier Concentration on Diffusion Probed by Triplet-Triplet Energy Transfer (Worrall and Wilkinson, 1996)... 

TABLE IV Effect of Modifier Concentration on Extraction Efficiencies for Shale Rock Using On-Line SFE/GC... 

Figure 1. Effect of modifier concentration on modulus of resultant silicone encapsulant.

Pt/silica catalysts were used to determine the effects of modifier concentration and temperature on enantiomeric excess. 2.5% Pt/silica, pre-modified in 0.34mM cinchonidine and used at 313 K gave an initial enantiomeric excess of 40%(/ ) but this value decayed to zero over 3.5 h (Figure 3). By contrast, pre-modification in 3.4mM cinchonidine gave a catalyst which improved in performance over the first hour of use and thereafter gave ee = 34 2%. Temperature was varied over the range 298 to 313 K Figure 4 shows that 313 K provided optimum performance. 

Figure 2. Effect of modifier concentrations on ee and average rate (10 mmol/s) (10 g ketoacid, 20 ml EtOH/10% HjO, lg5R94,100bar,RT)...

Figure 5.9 Effect of modifier concentration on the activation index of the whiskers.

DR Worrall, FJ Tlkinson. Photochemistry in modified supercritical carbon dioxide. Effect of modifier concentration of diffusion probed by triplet-triplet energy transfer. Chem Soc Faraday Trans 92 1467, 1996. 

The reactive compatibilization of HDPE-NBR and PP-NBR blends has been studied by Thomas and coworkers [75,76]. The maleic anhydride modified polyolefins and phenolic modified polyolefins are used as com-patibilizers. The effect of the concentration of these compatibilizers on the compatibility of these blends was investigated in terms of morphology and mechanical properties. It was found that in these blends an optimum quantity of the compatibilizer was required to obtain maximum improvement in properties, and after that a leveling off was observed. The domain size of the dispersed NBR phase in these blends is decreased up to a certain level and then increases (Fig. 12 and 13). The reduction in domain size is attributed to the increase in... 

A kinetic model describing the HRP-catalyzed oxidation of PCP by H202 should account for the effects of the concentrations of HRP, PCP, and H202 on the reaction rate. To derive such an equation, a reaction mechanism involving saturation kinetics is proposed. Based on the reaction scheme described in Section 17.3.1, which implies that the catalytic cycle is irreversible, the three distinct reactions steps (Equations 17.2 to 17.4) are modified to include the formation of Michaelis-Menten complexes ... 

The effect of oxygen concentration is thus included in a constant m, which modifies both the resulting maximum of the chemiluminescence intensity and the apparent rate constant k of hydroperoxide decomposition. 

Para-selectivity for a wide variety of ZSM-5 preparations of comparable activity are shown in Figure 12. These data include results for unmodified HZSM-5 s of varying crystal size as well as chemically modified HZSM-5 s. Since the activity of these catalysts is nearly identical, these data clearly establish the major role of diffusion in the para-xylene content of the xylenes produced in TDP. We have examined in more detail the effect of the concentration of one of these chemical modifiers, MgO. 

So far only the reactants directly involved in a reaction have been considered in their contribution to the rate law. Added inert cations and anions can sometimes contribute in a profound way by modifying the major reactants (e. g. by ion pairing) but usually the effects of their concentrations on the rates of reactions are best accommodated by the general theories of the effect of ionic strength on the reaction rate (Sec. 2.9.1). 

The amount of modifier required to prevent third phase formation can be determined in the following way. The aqueous and solvent phases are first contacted, and once the three phases have separated, the lower aqueous phase is drawn off and discarded. The modifier to be considered is then added from a burette in small increments to the two organic phases, and the mixture shaken after each addition. The amount of modifier required to produce a single organic phase is then used to calculate the amount required to be added to the solvent. Generally, about 2-5 vol% of modifier is needed, but more may be necessary if high concentrations of extractant are used in the solvent. Any effects of modifiers on the kinetics and equilibria of metal extraction and stripping can be determined by shakeout tests. 

Mass and heat transfer between the bulk fluid phase and the external catalyst surface can have an affect on reaction rates, and hence the selectivity, because of modified concentration and temperature driving forces. Such effects are unimportant for porous catalysts, but are significant for catalysis by non-porous metallic gauzes (for example, in NH3 oxidation referred to in Sect. 6.1.1). 

Alvarez, M. D., Canet, W., Fernandez, C. (2007a). Effect of modified starch concentration and freezing and thawing rates on properties of mashed potatoes (cv. Kennebec). J. Sci. FoodAgric., 87,1108-1122. 

Fig. 11. Effect of NaBr concentration of modifying solution on amount of adsorbed TA or NaBr and enantioface-differentialing ability of TA-NaBr-MRNiA ( ) TA ( ) OY (O) Br. Catalyst RNiA (TA) (RNi pretreated with % TA at pH 3.2 and 100 C for I hr). Modifying condition TA (1%) + NaBr, pH 5.0, 0°C. Reaction conditions MAA (11.5 ml), methyl propionate (23 ml), AcOH (0.2 ml), 100 C, 110-130 kg/cm2.

The X-ray diffraction peaks observed in the range of 3°-10° for the modified clays disappear in the rubber nanocomposites. photographs show predominantly exfoliation of the clays in the range of 12 4 nm in the BIMS. Consequently, excellent improvement in mechanical properties like tensile strength, elongation at break, and modulus is observed by the incorporation of the nanoclays in the BIMS. Maiti and Bhowmick have also studied the effect of solution concentration (5, 10, 15, 20, and 25 wt%) on the properties of fluorocarbon clay nanocomposites [64]. They noticed that optimum properties are achieved at 20 wt% solution. At the optimized solution concentration, they also prepared rubber/clay nanocomposites by a solution mixing process using fluoroelastomer and different nanoclays (namely NA, 10A, 20A, and 30B) and the effect of these nanoclays on the mechanical properties of the nanocomposites has been reported, as shown in Table 4 [93]. 

Top) Toxicity of various resveratrol concentrations against Salmonella typhimurium tester strain TA-102 in a histidine-containing medium. (Bottom) Antimutagenic effect of resveratrol concentrations in a modified Ames test employing strain TA-102 and hydrogen peroxide. 

A method involving electrometric titration depends on the volumetric reduction of selenious acid to selenium by means of titanium sulphate. The method is rapid and accurate5 if the solution is in cold concentrated hydrochloric acid saturated with sodium chloride. The presence of the latter is important, for it ensures rapid and uniform coagulation of the selenium hydrosol and increases the sharpness in the change of voltage at the end-point. The use of the hydrochloric acid in the cold eliminates the otherwise almost inevitable loss of selenium by volatilisation. Under these conditions any tellurium which may be present is unreduced and only has the effect of modifying the nature of the end-point.6... 

In addition to high-performance liquid chromatography (HPLC), the chiral resolution using CMPAs was also carried out by supercritical fluid chromatography (SFC) [91] and capillary electrochromatography (CEC) [92-98]. Salvador et al. [91] used dimethylated /1-cyclodextrin as the mobile phase additive on porous graphite carbon as the solid phase for the chiral resolution of tofizopam, warfarin, a benzoxazine derivative, lorazepam, flurbiprofen, temazepam, chlorthalidone, and methyl phehydantoin by SFC. The authors also studied the effect of the concentration of dimethylated /1-cyclodextrin, the concentration of the mobile phase, the nature of polar modifiers, outlet pressure, and the column temperature on the chiral resolution. 

FIGURE 11 Effect of the concentrations of organic modifiers in TLC (a) of acetonitrile on the chiral resolution of dansyl-DL-serine, (O) D- and ( ) L-enantiomers (from Ref. 101), and (b) of methanol on the chiral resolution of RS-aminoglutethimide (from Ref. 103). 

If the concentration of reducing gas is rather high and the effect of oxygen concentration cannot be ignored in the catalytic oxidation of reducing gas, we should modify Eq. 1 as follows ... 

The assay procedure was modified to study the effect of solvent concentration and use of CPO with in situ H202. To produce H202 in situ, 24 pmol of glucose and 20 ig GOx were added in a 3 mL reaction mixture. The disappearance of MCD was monitored spectrophotometrically at 278 nm with an extinction coefficient of 12,200 M 1 cm The various enzymatic reactions are as follows ... 

Smith and Sanagi reported the packed-column SFC of benzodiazepines (diazepam, lorazepam, lormetazepam, nordazepam, temazepam, es-trazolam, chlordiazepoxide, triazolam, cloxazolam, ketazolam, and lopra-zolam) with methanol-modified carbon dioxide as the mobile phase [29]. The effect of methanol concentration on separation was studied on three columns polystyrene-divinylbenzene, octadecylsilane, and cyanopropyl-bonded silica columns. They concluded that proportion of methanol has marked effect on the selectivity of compounds containing different functional groups. 

Figure 7.43. Effects of glycerol concentration and temperature on activities of A4-LDH from an Antarctic notothenioid (Parachaenichthys charcoti) and a warm-temperate goby fish (Gillichthys mirabilis). Inset the effects of glycerol concentration on the two orthologs at physiological temperatures of the species, 0°C for P. charcoti and 20°C for G. mirabilis. (Modified after Fields et al., 2001.)...

Shakeel-Ur-Rehman, Waldron D., Fox P.F. 2004. Effect of modifying lactose concentration in cheese curd on proteolysis and in quality of Cheddar cheese. Int. Dairy J. 14, 591-597. 

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