Mechanical and chemical actions

Both mechanical and chemical action promote ink detachment from cellulose fibers during pulping. Mechanical action includes interfiber abrasion and fiber flexing and bending. Chemical action includes fiber swelling and surfactant-promoted ink particle emulsification and solubilization. 

When looking at Sinner s famous circle that describes wash performance as the result of four components - temperature, time, mechanical and chemical action, it becomes clear that with decreasing wash temperature and time, chemistry has to become all the more sophisticated. 

Wood is converted to pulp by mechanical and chemical actions, which constitute the pulping process. Their selection depends upon the type of wood supply available and the pulp qualities desired. Pulps can be characterized on the basis of the unbleached pulp yields achieved by the pulping process used, i.e.. the yield of oven-drv (OD) pulp obtained from oven-dry debarked wood. 

Whitening of teeth can occur by two mechanisms. One method is mechanical, in which an abrasive is used to remove debris from the tooth. The other method involves either the use of peroxides, which react with water to form free oxygen radicals that help to whiten the teeth or a combination of mechanical and chemical actions. This latter mechanism is found with bleaching agents and is longer lasting than whitening procedures. 

Felting (1686) n. (1) The process of exposing wool fibers alone or in combination with other fibers to mechanical and chemical action, pressure, moisture, and heat so that they tangle, shrink, and mat to form a compact material. Felting is generally carried out in a fulling mill. (2) See needle-punching and needled fabric. 

Paint films also may be required to resist acids and alkalis, solvents, staining, heat, impact, marring, and abrasion. Some coatings must be able to withstand flexing without cracking or flaking. Table 5 lists paints that have proven successful in withstanding mechanical and chemical action. 

Effects of Liquid Velocity. When a liquid passing over an aluminum surface exceeds a certain velocity, grooves can be worn in the surface, the probable result of mechanical and chemical action. This phenomenon does not usually occur on aluminum at velocities below 3 m/s (10 ft s). 

A needled felt, on the other hand, is a fabric composed of natural, synthetic, or a combination of natural and synthetic fibers physically interlocked by the action of a needle loom with or without combination of other textile fabrics and with or without suitable combination of mechanical work, chemical action, moisture, and heat, but without weaving, knitting, stitching, thermal bonding, or adhesives (16). 

The particle size of typical natural mbber latex ranges from slightly higher than 1 )Tm to as small as 20 nm, and can be destabilized by mechanical or chemical action. Machinery used to stir or maintain latex circulation should be designed to minimize fluid shear, particularly where that may be locally intensified, eg, at the junction of blade with shaft. 

Chemically active These filters are similar in design to the non-active depth units but the filtering media used are so chosen that contaminants adhere by chemical attraction. Thus there is a dual action, mechanical and chemical. The materials used include various activated clays. Fuller s earth, charcoal and chemically treated paper. Their cleansing action is much more thorough than that of the purely mechanical devices, for they are capable of removing matter actually in solution in the oil. 

Begun in 1944 with DDT and in 1947 with parathion, the present report includes analytical data secured from certain chemical, mechanical, and solvent actions on apples, pears, lemons, and oranges. In the absence of established tolerances for these two insecticidal materials, it is hardly possible to interpret the significance of many of these data with respect to consumer hazard. 

The fundamental difference between this process and bulk fermentation or sponge batter processes is that the dough development is achieved by a combination of high mechanical energy and chemical action. 

It is claimed that the cost of hydrogen by this process is exceedingly low consequently, if this is correct and the mechanical difficulties of manufacturing generators to withstand the very high pressures and chemical action are satisfactorily overcome, this process would appear to be one of the highest value for the commercial production of hydrogen. 

Needham, P. H. Pulman, D. "Mechanism and Pesticide Action" American Chemical Society Washington, D. C., 1974 ACS Symposium Series No. 2, 80. 

The peripheral component of their analgesic action is due to the inhibition of prostaglandin synthetase and thereby inhibiting the synthesis of prostaglandins (PGs) which sensitise the pain receptors to mechanical and chemical stimuli. Aspirin inhibits prostaglandin synthesis and blocks the sensitization of pain mechanism. 

For metals in general, any mechanical or chemical action that alters the crystalline perfection will raise the residual resistivity and, therefore, the total resistivity, according to Eq. (6.16). Thus, vacancies in metals, in contrast to those in ionic solids, increase the resistivity. The reason for this lies in the inherent differences between condnc-tion mechanisms in these two classes of materials. The differences between ionic and electronic conduction will be elaborated upon in Section 6.1.2. 

Weathering is the process by which rock is broken down into smaller and smaller particles. It involves both mechanical and chemical breakdowns. The mechanical breakdown into smaller and smaller pieces occurs as a result of exposure to freeze-thaw cycles and to the action of wind and water. Chemical breakdown occurs as a result of exposure to air and water and other chemicals that may be dissolved in water, such as acids. Weathering by exposure to atmosphere results in some of the carbon dioxide being removed from the atmosphere along with the broken-down rock and eventually washed into the ocean. 

Listed below are some of the energy sources which are capable of unintentionally initiating EED s electrically connected circuitry (induction), electromagnetic radiation, electrostatic charges, mechanical, thermal and chemical action... 

Waterside problems that lead to decreases in efficiency and material deterioration can be caused by a variety of mechanisms, such as electrochemical corrosion and deposition of foulants. These problems can be exacerbated by low flow, poor operational practice, process contamination, or specific stresses. It is also important to try to determine cause and effect relationships in order to provide a logical and practical water treatment solution. Such a solution will usually involve some form of cleaning, plus a combined engineering and chemical action plan. Inspection may be made easier by the use of a Boroscope or similar optical/video recording device. The color, texture, and quantity of all deposits should be noted, measurements of pits taken, and microbiological contaminants analyzed. It may be useful to conduct biocide efficiency tests on bacterial slimes. The period when a heat exchanger is open for inspection may be an opportune time for the permanent installation of ports for corrosion-monitoring probes. 

The general usage of the terms lyophilic and lyophobic in describing colloidal systems is somewhat illogical. Lyophobic traditionally describes liquid dispersions of solid or liquid particles produced by mechanical or chemical action however, in these so-called lyophobic sols (e.g. dispersions of powdered alumina or silica in water) there is often a high affinity between the particles and the dispersion medium - i.e. the particles are really lyophilic. Indeed, if the term lyophobic is taken to imply no affinity between particles and dispersion medium (an unreal situation), then the particles would not be wetted and no dispersion could, in fact, be formed. Lyophilic ... 

Mechanism of action The antipyretic and anti-inflammatory effects of the salicylates are due primarily to the blockade of prostaglandin synthesis at the thermoregulatory centers in the hypothalamus and at peripheral target sites. Furthermore, by decreasing prostaglandin synthesis, the salicylates also prevent the sensitization of pain receptors to both mechanical and chemical stimuli. Aspirin may also depress pain stimuli at subcortical sites (that is, the thalamus and hypothalamus). 

Nonwoven fabrics are fibrous sheets made without spinning, weaving, or knitting. They include felts, bonded fabrics, and papers. The interlocking of fibers is achieved by a combination of mechanical work, chemical action, moisture, and heat by either textile or paper making processes. 

Wood Pulp.—The methods for converting the wood into pulp are two, viz., mechanical and chemical. In the former the wood is mechanically cut into pieces, the knots removed and then the pieces shredded into fibrous material and carried away by water. By the action of water it is converted into a pulp and separated into grades by means of sieves. The fine watery pulp is then pressed into sheets and dried. The product is known as dry pulp and is stock material for making... 

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