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Temperature at low

This is a classical result valid only at high temperatures. At low temperatures, quantum mechanical attributes of a degree of freedom can partially or fully freeze it, thereby modifying or removing its contribution to U and... [Pg.392]

For example, when an N-methylthioacetamide (96), R, = R — Me, was condensed with chloroacetone, a 2,3,4-trimethylthiazolium chloride was obtained in quantitative yield. The reaction is usually run in aqueous or alcoholic solution at room temperature. At low temperature, with N-phenylthioacetamide (96), Rj = Me, R2 = Ph and chloroacetone, an acyclic intermediate (98) was isolated and characterized (Scheme 43). It was easily converted to 2,4-dimethyl-3-phenylthiazolium chloride (97), R, = Rs = Me, Rj -Ph, by heating (99,102, 145). [Pg.211]

The Metravib Micromecanalyser is an inverted torsional pendulum, but unlike the torsional pendulums described eadier, it can be operated as a forced-vibration instmment. It is fully computerized and automatically determines G, and tan 5 as a function of temperature at low frequencies (10 1 Hz). Stress relaxation and creep measurements are also possible. The temperature range is —170 to 400°C. The Micromecanalyser probably has been used more for the characterization of glasses and metals than for polymers, but has proved useful for determining glassy-state relaxations and microstmctures of polymer blends (285) and latex films (286). [Pg.200]

Diffusional flow is important when grains are small (as they often are in ceramics) and when the component is subject to high temperatures at low loads. To select a material which resists it, you should... [Pg.192]

Surface Temperatures. At low temperatures, the oxidation reaetions on the eatalyst are kinetieally eontrolled, and the eatalyst aetivity is an important parameter. As the temperature inereases, the build-up of heat on the eatalyst surfaee due to the exothermie surfaee reaetions produees ignition and the eatalyst surfaee temperature jumps rapidly to the adiabatie flame temperature of the fuel/air mixture on ignition. Figure 10-26 shows a... [Pg.404]

The chemical structure of SBR is given in Fig. 4. Because butadiene has two carbon-carbon double bonds, 1,2 and 1,4 addition reactions can be produced. The 1,2 addition provides a pendant vinyl group on the copolymer chain, leading to an increase in Tg. The 1,4 addition may occur in cis or trans. In free radical emulsion polymerization, the cis to trans ratio can be varied by changing the temperature (at low temperature, the trans form is favoured), and about 20% of the vinyl pendant group remains in both isomers. In solution polymerization the pendant vinyl group can be varied from 10 to 90% by choosing the adequate solvent and catalyst system. [Pg.586]

Figure 16-12 shows the effect of ambient temperature on the horsepower output of a typical two-shaft gas turbine engine. At high temperatures the horsepower is limited by the maximum allowable power turbine inlet temperature. At low ambient temperatures, the available horsepower is limited by the maximum allowable air compressor speed. [Pg.482]

The decanted aqueous phase was extracted three times with a total of 150 ml of ethyl acetate. The combined organic solutions were filtered over Clarcel and extracted three times with a total of 150 ml of an Iced normal aqueous methane-sulfonic acid solution. The combined acid extracts were rendered alkaline on an ice bath with 30 ml of ION caustic soda solution. The separated oil was extracted four times with a total of 200 ml of ether. The combined ethereal extracts were washed twelve times with a totai of 360 ml of distilled water, dried over anhydrous magnesium sulfate in the presence of 0.3 g of animal charcoal and evaporated under reduced pressure on a water bath at 40°C. The oily residue obtained (3.8 g) was dissolved in 30 ml of boiling acetonitrile. After cooling for 2 hours at 3°C, the crystals formed were separated, washed with 5 ml of acetonitrile and dried at ambient temperature at low pressure. [Pg.1347]

Numerous experimental studies have shown that the magnetic hyperfine field of magnetic nanoparticles varies linearly with temperature at low temperatures, in accordance with (6.23). This is in contrast to bulk materials for which the decrease in the hyperfine field with increasing temperature in accordance with spin wave... [Pg.225]

The main conclusions of the strain induced crystallization behavior of high trans polybutadiene based rubber and natural rubber are (1) the rate of crystallization is extremely rapid compared to that of NR (2) the amount of strain induced crystallization is small compared to that of NR, especially at room temperature and (3) for the high trans SBR s relative to NR, crystallization is more sensitive to temperature at low extension ratios, and crystallization is less sensitive to strain. [Pg.96]

Addition of HSiMeCl2 to cyclopentadiene is catalyzed by (42) at room temperature at low catalyst loading (0.01 mol.%) to give the (S)-allylsilane in moderate ee.125 This enantioselectivity can be enhanced dramatically with incorporation of perfluoroalkyl groups into the amine functionality (Scheme 26).126... [Pg.285]

The predicted effects of temperature on (/m/ wcrc experimentally observed by Botterill and Teoman (1980) as shown in Fig. 3. For sand particles 462 microns in diameter, they observed that Umf- decreased with temperature. For larger material (2320 microns) in the transition region in Fig. 2 (where (/ changes from increasing with temperature to decreasing with temperature), they observed an initial increase in f/ / w ith temperature at low temperatures, which was followed by a decrease in Umjras increasing temperature caused viscous effects to become dominant. [Pg.117]

Investigate the batch reactor for the case of an equilibrium reaction. Reset the equilibrium constant to the original value in the program. Run first the batch reactor isothermally in the range of 300 to 400 R and determine the equilibrium conversion. Use the Parameter Plot tool for this to obtain the values at each temperature. At low temperatures make sure the STOPTIME is always sufficiently long to reach equilibrium. Using the same temperatures as in Exercise 1, find the reaction times to achieve fraction conversions XA of 90, 95 und 99%. [Pg.309]

Nitric oxide is thermochemically the least stable of the nitrogen oxides, and while it is quite stable at room temperature at low pressures, it decomposes at a measurable rate at pressures of 100 atm. Melia178 has shown that, in the temperature range 30-50 °C and for pressures up to 400 atm, the NO decomposition is represented approximately by... [Pg.77]

In summary, there is a clear mineralogical control on the partitioning of the Mg isotopes among carbonates and waters and, apparently, a weak dependence on temperature at low T. An important question is the extent to which these measured values for carbonates and waters reflect isotopic equilibrium. Hints to the answer come from comparing 5 Mg to 5 Mg, as shown in the section on terrestrial reservoirs. [Pg.205]

In most reactions, the entropy of the system increases (S is positive), so the value of -TAS is negative. Therefore, most reactions tend to be more favourable at higher temperatures. At low temperatures, reactions are likely to be favourable only if they are highly exothermic. [Pg.332]

At variance with the manganese(II) concanavalin A, the relaxivity of which increases with increasing temperature at low field, indicating the... [Pg.157]

An interesting class of polymer matrices widely employed for CSE consists of temperature-dependent, viscosity-adjustable polymer solutions that are filled into the capillary at one temperature at low viscosities and are used in separation at another temperature at entanglement threshold concentrations and higher viscosities. Such viscosity-adjustable polymers are termed thermoresponsive... [Pg.187]

As a precaution, therefore, a Roots pump should always be inserted in front of the condenser at low inlet pressures so that the condensation capacity is essentially enhanced. The condensation capacity does not depend only on the vapor pressure, but also on the refrigerant temperature. At low vapor pressures, therefore, effective condensation can be obtained only if the refrigerant temperature is correspondingly low. At vapor pressures below 6.5 mbar, for example, the insertion of a condenser is sensible only if the refrigerant temperature is less than 0 °C. Often at low pressures a gas -vapor mixture with unsaturated water vapor is pumped (for further details, see Section 2.1.5). In general, then, one can dispense with the condenser. [Pg.63]


See other pages where Temperature at low is mentioned: [Pg.258]    [Pg.806]    [Pg.131]    [Pg.302]    [Pg.416]    [Pg.345]    [Pg.524]    [Pg.15]    [Pg.221]    [Pg.39]    [Pg.95]    [Pg.367]    [Pg.267]    [Pg.77]    [Pg.333]    [Pg.89]    [Pg.306]    [Pg.343]    [Pg.235]    [Pg.87]    [Pg.578]    [Pg.170]    [Pg.267]    [Pg.625]    [Pg.322]    [Pg.53]    [Pg.262]    [Pg.306]    [Pg.897]    [Pg.345]    [Pg.195]   
See also in sourсe #XX -- [ Pg.372 ]

See also in sourсe #XX -- [ Pg.372 ]




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A Model Description of the Thermal Behavior at Low Temperature

Adsorption at low temperatures

Anodic Oxidation of Fuels at Low Temperatures

Anodic Oxidation of Molecular Hydrogen at Low Temperatures

Are More Soluble at Low Temperatures and High Pressures

Attainment of Perfect Order at Low Temperatures

Behavior at low and high temperature

Behavior at low temperatures

Carbon Monoxide at Low Temperatures

Conductivity at Low Temperatures

Conductivity at Very Low Temperatures

Contraction at low temperatures

Crystal structures at low temperature

Crystallization at low-temperature

Deformation at Low Temperatures

Ductile Ceramics at Low or Ambient Temperatures

Ductility at low temperatures

Electrical Properties at Low Temperatures

Electrodes at Low Temperatures

Equation of state for ideal gases at very low temperatures

Fractionation at low temperatures

Free radicals and their reactions at low temperature using a rotating cryostat

Free radicals and their reactions at low temperature using a rotating cryostat, study

Free radicals, and their reactions at low temperature using a rotating

Heat capacity at low temperatures

Hydration at low temperatures

Inversion temperature at low density

Kinematic Viscosity of 60 levo-2,3-Butanediol, Glycerol and Ethylene Glycol Solutions at Low Temperatures

Measurements at low temperatures

Mechanical Properties at Low Temperatures

Multi-axial deformation correspondences of shear, tension, and compression at low temperatures

ORR Kinetics at Low Temperatures

Operation at low ambient temperatures

Organometallic Complexes Observed at Low Temperature in Rare Gas or Other Media

Oxidation at low temperature

Oxidation of CO at low temperatures

Oxygen at low temperature

Physical properties at low temperatures

Polymerization of Isobutylene with Gaseous BF3 at Low Temperatures in Bulk

Polymers in Poor Solvents or at Low Critical Solubility Temperature

Prebiotic Reactions at Low Temperatures

Protein at low temperatures

Proton Conductivity at Low Temperature

Raman spectroscopy, at low temperature

Reactions at low temperatures

Reduction at low temperature

Single Crystal Diffraction Studies at Low Temperatures

Solid matrices at low temperature

Specific Heats of Solids at Very Low Temperatures

Spectral Diffusion due to Tunneling Processes at very low Temperatures

Spectroscopy at low temperatures

Structural Properties at Low Temperatures

Study of free radicals and their reactions at low temperatures using a rotating cryostat

The Creation of Point Defects at Low Temperature

The Oxygen Electrode at Low Temperatures

The Thermal Behavior at Low Temperature

Thermal Conductivities of Insulating Materials at Low Temperatures (Grober)

Thermal Conductivity at Low Temperatures

Thermal Properties at Low Temperatures

Trapped and Solvated Electrons at Low Temperatures

Volatility at low temperature

Why Are Thermophilic Enzymes Poorly Active at Low Temperature

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