Humidity processes

If substantial changes in other parameters are expected (environmental humidity, processing temperatures as a result of heater capabilities, etc.), then better predictions can be made using the thermodynamic principles outlined in the section, Thermodynamics of the Film-Coating Process. ... 

When the alloy under assay Contains either motfaury Ot lead, the results obtained by the humid process are hot exact, since these metals are precipitated with the silver, and decompose a portion bf the normal Solution, which vitiates the Conditions of tho experiment. The presence of mercury is indicated when a difficulty Is experienced in obtaining a transparent solution by agitation and When that Is the base, the assay is not to1 be relied on. The assay of alloys Containing mercury may, however, he made by the harm d process, by adding ft solution of acetate of soda to tho nitric acid Iiqnor containing the silver, previously to tho introduce tion of the normal solution, as the acetate prevents tho formation of the chloride of mercury. 

Figue 11-23. Tensile stress at break (tensile strength) ob of at-poly(styrenes) of narrow molar mass distribution and various number-average molar masses M . Measurements were made at 23°C and 50% relative humidity. Processing was by compression molding ( ) or injection molding (O ) Injection-molded samples are oriented. (After H. W. McCormick, F. M. Brower, and L. Kin.)... 

Direct in-situ atmospheric observations of humidity-induced restructuring are difficult to obtain and remain sparse. Most evidence for humidity processing has come from laboratory and ground-based measurements. Trials on the humidity processing of atmospheric samples attributed a decrease in size to the restructuring of freshly emitted smoke [69]. In the same trials, laboratory experiments indicated that aggregate... 

Environmental variables - temperature, humidity, process and plant layouts, distribution of contaminants... 

The hydration shell is formed with the increasing of the water content of the sample and the NA transforms from the unordered to A- and then to B form, in the case of DNA and DNA-like polynucleotides and salt concentrations similar to in vivo conditions. The reverse process, dehydration of NA, results in the reverse conformational transitions but they take place at the values of relative humidity (r.h.) less than the forward direction [12]. Thus, there is a conformational hysteresis over the hydration-dehydration loop. The adsorption isotherms of the NAs, i.e. the plots of the number of the adsorbed water molecules versus the r.h. of the sample at constant temperature, also demonstrate the hysteresis phenomena [13]. The hysteresis is i( producible and its value does not decrease for at least a week. 

Poly(vinyl cinnamate) Resists. Dichromated resists exhibit numerous shortcomings which include lot-to-lot variabiUty of the components, aging of the formulated resists in solution and in coated form, poor process stabiUty (due to a sensitivity to variations in temperature and humidity), and intrinsically low photosensitivity requiring long exposure times for adequate insolubilization. 

Process Requirements. Typical inside dry-bulb temperatures and relative humidities used for preparing, processing, and manufacturing various products, and for storing both raw and finished goods, are Hsted in Table 1. In some instances, the conditions have been compromised for the sake of worker comfort and do not represent the optimum for the product. In others, the conditions Hsted have no effect on the product or process other than to increase worker efficiency. 

Where highly poHshed surfaces are manufactured or stored for short intervals between different phases of processing, relative humidity and temperature are both maintained constant to minimise surface moisture films. If these surfaces are shipped or stored for extended intervals, protective coverings or coatings may be required. 

Some industrial processes produce predorninately latent air conditioning loads. Others dictate very low humidities and when the dew point falls below 0°C, free2ing becomes a major concern. Dehydration equipment, using soHd sorbents such as siUca gel and activated alurnina, or Hquid sorbents such as lithium chloride brine and triethylene glycol, may be used. The process is exothermic and may require cooling the exiting air stream to meet space requirements. Heat is also required for reactivation of the sorbent material. 

Electrical Behavior. The resistivity of acetate varies significantly with humidity with typical values ranging from 10 ohm-cm at 45% rh to 10 ohm-cm at 95% rh (16). Because of the high resistivity both acetate and triacetate yams readily develop static charges and an antistatic finish is usually apphed to aid in fiber processing. Both yams have also been used for electrical insulation after lubricants and other finishing agents are removed. 

Dehydration Processing. Dehydration is one of the oldest means of preserving food. Microbes generally do not grow below a minimum water activity, of 0.65 defined as the equiHbrium relative humidity surrounding food ia a sealed container at a given temperature, ie, no microbes can... 

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