Wet heat

Dimensional Stability. The wet heat resistance of PVA fiber is indicated by the wet softening temperature (WTS) at which the fiber shrinks to a specified ratio. At one time, the WTS was not more than 95°C for nonacetalized PVA fiber, but improvement of WTS has been achieved by improvement in heat-drawing and -treating techniques other methods proposed include suppression of polymerization temperature of vinyl acetate (36) and employment of alkafi spinning (37). 

The guarded hot-plate method can be modified to perform dry and wet heat transfer testing (sweating skin model). Some plates contain simulated sweat glands and use a pumping mechanism to deUver water to the plate surface. Thermal comfort properties that can be deterrnined from this test are do, permeabihty index (/ ), and comfort limits. PermeabiUty index indicates moisture—heat permeabiUty through the fabric on a scale of 0 (completely impermeable) to 1 (completely permeable). This parameter indicates the effect of skin moisture on heat loss. Comfort limits are the predicted metaboHc activity levels that may be sustained while maintaining body thermal comfort in the test environment. 

Phase C corresponds to a decreasing rate of temperature rise in the board core at about 100°C. It is followed by stabilization of the temperature, namely phase D. This latter being due to decrease of the steam gradient due to moisture escape from the board edges, and the increase and decrease of the wood wetting heat, respectively, near the board surface and in the core layer. Phase E, a new slow increase in temperature is observable in standard moisture content boards [225] but is absent at high moisture content (due to the maintenance of some moisture in the core layer), contrary to the case of traditional moisture content adhesives, as shown in Fig. 8. 

Figure 7.6 Peptides do not denature after baking (dry heat) or deparaffinization and antigen retrieval (wet heat). Peptide-coupled slides were treated as indicated on the Y-axis and then immunohistochemically stained. In this particular example, an ER peptide with an ER MAb was used. The resulting peptide spot intensity (mean pixel intensity on a 1-256 scale) was measured and is shown on the y-axis.The data represent the means and SD or triplicate measurements. The experiments on the left (solid bars) and the right (hatched bars) were conducted at different times and have no connection to one another. Adapted with permission from Sompuram et al.6...

The surface area of PSs can be measured by means of quantitative electron microscopy (EM) [49-51], knowing the sizes of particles and pores [51,52], wetting heat [7,53] measurements, etc. But, the most universal methods are based on adsorption measurements [51,53-55], corresponding to the traditional methods of pore size distribution measurements in the range 0.3 to 100 nm. 

Protein quality studies evaluating various edible portions of the winged bean plant and the results of recent International Field Trials are reviewed. Research efforts have been focused upon the mature seed (protein content 20.7-45.9% in 240 accessions), which is occasionally eaten in parts of Indonesia and Papua, New Guinea. Autoclaved seed meal and wet heat treated seed meal provided a corrected PER value of 1.76 and 1.72 respectively, in comparison to casein control of 2.50. 

Matsumara, H., Studies on the mechanism of tablet compression and disintegration. IV. Evolution of wetting heat and its reduction by compressional force, Yakugaku Zasshi, 79 63-68 (1959). 

Despite some success with the above pretreatments, the development of wet heat-induced epitope retrieval (HIER) procedures has been the critical... 

With the assistance of wet-heat mediated antigen retrieval, most antigens of interest to a general histopathology laboratory can be detected in archival tis-... 

Dewax paraffin sections in three changes of xylene and ethanol for 2 min each. Apply wet-heat mediated antigen retrieval, pressure cooking or microwaving when appropriate (see Chapter 13). 

Possibility of operating partially or wholly in the vapour phase by varying the liquid flowrate according to catalyst wetting, heat of vaporization, and mass-transfer resistances in the liquid phase. 

Deikachar, H. S. R. (1972). Effect of wet heat treatment on the culinary qualities of ragi (Eleusine coracana). ]. Food Sci. Technol. 91,49-150. 

There are three critical times associated with all wet heat sterilization... 

Bl. Bagdi, E., Krenacs, L., Krenacs, T., Miller, K., and Isaacson, P. G., Follicular dendritic cells in reactive and neoplastic lymphoid tissues A reevaluation of staining patterns of CD21, CD23, and CD35 antibodies in paraffin sections after wet heat-induced epitope retrieval. Appl. Immuno-histochem. Mol. Morphol. 9, 117—124 (2001). 

Using exposure to higher temperature to accelerate bond degradation has been studied in detail by Gillespie and coworkers during the last 10 years. Most recently (48), effect of dry heat was compared to earlier work with wet heat. They concluded that the Arrhenius model does describe the degradation of the bonds,... 

Resistance to moisture Flexural strength Flexural modulus Tensile strength Postforming laminate only Postformability Blister resistance Melamine-faced chipboard only Resistance to wet heat Surface soundness Composite boards only ... 

Heat in wet + Heat conducted fabric entering from dry layer... 

There is, in addition, a readily recognizable rehydration rate dependence on the surface siloxane content. This is most apparent in the immersion heat data for silica FS, for which the time of slow heat evolution on immersion becomes appreciably longer for sample pretreatment temperatures above 225° C. Consideration of the precision of the calorimetric measurement with regard to slow heat input does not seem to have been afforded adequate attention. Immersion heat calorimeters constructed for the essentially instantaneous wetting heat measurement often do not perform adequately when heat is evolved slowly. 

Silk can absorb up to 30 % of its weight in moisture without creating a damp feeling. When moisture is absorbed it generates wetting-heat which helps to explain why silk is comfortable to wear next to the skin. 

The working principle is as follows. A cooling fluid at temperature Tj at the inlet is fed into the cooling jacket at a constant mass flow rate fand the wetted heat transfer area A r in the jacket (which can be varied in this calorime-... 

Wet heat 1 mg/mL heated under reflux for 2 h on water bath... 

Methods for stabilization of rice bran have been reviewed (37). These include dry heating, wet heating, and extrusion. The most practical method has been the use of extrusion or expansion methods. 

Wet heating is more effective for bran stabilization for oil extraction than is dry heating. Lipase is inactivated in 3 minutes at 100°C (37). The equipment that can be used include steam cookers, blanchers, autoclaves, and screw extruders with injected steam and water (30). Extrusion with steam injection and up to 10% added water reduces the temperature required for lipase inactivation. Temperatures are reduced to 100-120°C. Product may be held at 100°C for 1.5-3.0 minutes before drying to a stable moisture content. Bran expands as it exits the extruder, and water flashes to steam (8). Porous pellets assist in solvent percolation during oil extraction. Fines are agglomerated as well. 

Parboiling of rice is also an example of wet heat stabilization. The lipase in rough rice is completely inactivated by either autoclaving for 3-20 minutes or by parboiling. 

Pasteurization is the heating of aqueous, stabilized protein solutions. Pasteurization has been used for bulk preparations of Factor VIII, antithrombin III, and alphai-antitrypsin but wet heat treatment of these... 

The product Longdan Qiegan Wan ( Wetness Heat Pill) was removed from the Austrahan Register of Therapeutic Goods following the detection of aristolochic acid by laboratory testing by the Therapeutic Goods Administration (3). 

Plasma-derived factor VIII concentrates have been implicated in the transmission of the non-enveloped hepatitis A and parvovirus B19 (28). The virus-inactivating procedures now in use (chemical inactivation, wet-heat treatment, and nanofiltration) should provide coagulation factors without risk of transmitting HIV and with a very high safety for hepatitis virus. Nevertheless, recombinant factor VIII is considered a safer alternative. 

In human diets, leavening of bread and exposure of cereals to wet heat lower the phytate content, increasing zinc avahability. Other factors, such as dietary fiber and a constituent of beans, can also lower zinc intestinal absorption but to a lesser extent. Iron at supplemental dosages (up to 65 mg/day) may decrease zinc absorption so that pregnant and lactating women taking iron may require zinc supplementation, ... 

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