Subject temperature, effect

As described above, the temperature effect is useful for enhancing the enantioselectivity however, one problem is the decrease in the reaction rate. For example, although in a lipase AK-catalyzed resolution of solketal, the E value (9 at 30°C, Table 1, entry 1) is increased up to 55 by lowering the temperature to —40°C, 10 times the amount of lipase and 8-fold the reaction time are required as compared with those at 30°C. Thus, the rate of acceleration is an important subject especially to make the low-temperature reaction practical. 

The desirability of partial shade on tea estates has been a controversial subject. Desirable effects include temperature moderation at the leaf surface, which decreases low-humidity stress, and an increased yield of chlorophyll, amino acid, and caffeine production. The undesirable effects include decreased photosynthetic activity and competition for water and solid nutrients by the shade tree employed. In general, the trend has been toward the elimination of shade in most black-tea growing areas. Green tea products benefit from the additional chlorophyll and amino acid pro-... 

The recombinantly expressed nitrilase from Pseudomonas fluorescens EBC 191 (PFNLase) was applied in a study aimed at understanding the selectivity for amide versus acid formation from a series of substituted 2-phenylacetonitriles, including a-methyl, a-chloro, a-hydroxy and a-acetoxy derivatives. Amide formation increased when the a-substituent was electron deficient and was also affected by chirality of the a- stereogenic center for example, 2-chloro-2-phenylacetonitrile afforded 89% amide while mandelonitrile afforded 11% amide from the (R)-enantiomer but 55% amide was formed from the (5)-enantiomer. Relative amounts of amide and carboxylic acid was also subject to pH and temperature effects [87,88]. 

The major advantage of this detector is that it is almost universal. All substances have their own characteristic refractive index (it is a physical property of the substance). Thus, the only time that a mixture component would not give a peak is when it has a refractive index equal to that of the mobile phase, a rare occurrence. The disadvantages are that it is not very sensitive and the output to the recorder is subject to temperature effects. Also, it is difficult to use this detector with the gradient elution method because it is sensitive to changes in the mobile phase composition. 

In one study,human subjects were tested in a controlled-environ-ment chamber with a high (summer) temperature and with ozone, nitrogen dioxide, and carbon monoxide as pollutants. Performance on a divided-attention task given at the end of the exposure period and the subjects heartrate variability (a potential psychophysiologic measure of attention) were evaluated. The subjects displayed a significant decrement in peripheral attention associated with increased ambient temperature. Effects attributable to pollutant gases were variable. 

Acute exogenous administration of melatonin causes sedation, fatigue, self-reported vigor, confusion, and a reduction in body temperature in healthy subjects. The effects of chronic treatment have not been studied, and adverse effects have not been systematically reported. 

Brun et al. (216) evaluated the mental performance, hormone levels, and temperatures of eight sleep-deprived volunteers given 300-mg of modafinil at 22 00 and 08 00. Modafinil did not affect melatonin, cortisol, or growth hormone levels, but it did attenuate performance decrements, attenuate the nocturnal decrease in body temperature, and increase daytime body temperature. These temperature effects are different from what has been observed in non-sleep-deprived subjects. Bourdon et al. (217) found no effects of 200 mg of modafinil on thermal balance in neutral conditions and no effect on thermoregulation in cold conditions (despite a tendency toward greater reductions in core temperature when modafinil was applied in a cold environment). However, these authors did not examine temperature effects beyond 3 hr in the morning. The differences with... 

For temperature compensation, the most frequently employed method is the use of dummy elements. The dummy gauge is mounted on the same surfaces as the active element. It is exposed to the same temperature but is not subject to the forces applied. If such a dummy is connected in a Wheatstone bridge arm adjacent to the active element, it will automatically compensate for temperature effects. 

Many factors are involved in this complex reaction. Secondary thermal reactions follow the primary photo process and these are subject to temperature effects. At high intensities the reaction may be so rapid that diffusion of materials through the cell wall becomes a limiting factor and the quantum efficiency of the proc-... 

Studies of the temperature effect are one of the most interesting subjects in crystalline state polymerization since the temperature is closely related with molecular motion under the control of the crystal lattice. The effects of temperature on the polymerization rate and molecular weight of the polymer obtained have been studied for several monomers. Among these monomers, the effects have been fully investigated in the polymerization of p-PDA Et in the temperature range from 4.2 K (liquid helium) to temperatures above the crystal melting point19-28). 

In order to improve the model further we are currently taking quantum effects in the lattice into account, i.e. treating the CH units not classically but on quantum mechanical basis. To this end we use an ansatz state similar to Davydov s so-called ID,> state [96] developed for the description of solitons in proteins. However, there vibrations are coupled to lattice phonons, while in tPA fermions (electrons) are coupled to the lattice phonons. The results of this study will be the subject of a forthcoming paper. Further we want to improve the description of the electrons by going to semiempirical all valence electron methods or even to density functional theories. Further we introduce temperature effects into the theory which can be done with the help of a Langevin equation (random force and dissipation terms) or by a thermal population of the lattice phonons. Starting then the simulations with an optimized soliton geometry in the center of the chain (equilibrium position) one can study the soliton mobility as function of temperature. Further in the same way the mobility of polarons can be... 

Interestingly, the viscosity of polysoap solutions is frequently subject to important ageing effects [75,99,130,163,284] and temperature effects [75,130], dropping asymptotically towards its final value. The decrease can amount to 90% of the initial value and can endure for up to one month [99, 163]. These effects are not well understood but are putatively attributed to conformational changes. The phenomenon has to be kept in mind when evaluating viscosity data, and should always be verified - or excluded - in viscosity studies of polysoaps. 

This paper is a contribution to the subject of thermal effects on the mechanical behaviour of clays. We concentrate here on the presentation of experimental results obtained on a Kaolin clay under triaxial conditions at two temperatures (22 °C and 90 °C), in view of determining the evolution of the shear yield surface with temperature. A new temperatureapparatus developed by the authors was used (Cekerevac et al. 2(X)3). Temperature effects were identified by comparing the results of tests... 

The sea-air CO2 flux estimated above is subject to three sources of error (1) biases in sea-air ApC02 values interpolated from relatively sparse observations, (2) the skin temperature effect, and(3) uncertainties in the gas transfer coefficient estimated on the basis of the wind speed dependence. Possible... 

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