Physical conversion

Modification, which involves the alteration of the physical and chemical characteristics of the native potato starch to improve its fimctional characteristics, can be used to tailor it to specific food applications. The rate and efficacy of any starch modification process depend on the botanical origin of the starch and on the size and structure of its granules. This also includes the surface structure of the granules, which encompasses the outer and iimer surface depending on the pores and channels, which cause the development of the so-called specific surface (Juszczak, 2003). Potato starch modification can be achieved in three different ways physical, conversion, and chemical (derivatization) (Table 10.6). 

In keeping with the older definitions of terms that are part of polarimetry, there are definitions for specific ellipticity [T ] = P.c. d, and molecular ellipticity [0] = [T ] M/lOO, where M is the molar mass. With appropriate substitutions, the molecular ellipticity can be expressed in terms of e, namely [0] = 3300(8/, Br) = 3300 Ae. The numerical constant is the result of all the physical conversion factors. 

Chipping, the process of reducing a log to chips of about 2.5 x 2.5 x 0.5 cm thick is a common preliminary to all pulping methods except stone groundwood. Wood chips are more convenient and uniform for solids transport within the mill complex by conveyor belt or pneumatic delivery systems than are whole logs. Also a chip format is more amenable to direct physical conversion to fibers because of the much easier and more uniform penetration of heat and moisture through the thin sections of wood. 

The means of signal transformation (appropriate physical conversion processes). 

First, let s glance back at the industry which we serve. Since its inception, the chemical industry has been concerned with the chemical or physical conversion of process materials to different forms of utility. The evolution of chemical production through the years has gone from batch processes to continuous processes—with ever-increasing automation made possible by improved instrumentation. 

In a chemical production plant, products are produced by the chemical and physical conversion of raw materials or intermediate products. The production unit is a completely integrated technical operating unit on the site. It is connected with other units on the site by transportation and personnel routes, and pipelines for raw materials, auxiliary substances, products, utilities, and energy. It usually consists of the actual production unit and several off-site facilities, as shown in Fig. 1-1. 

Particulate pollutants are emitted from many sources. Additionally, particles are formed in the atmosphere by both chemical and physical conversions from natural and anthropogenic gaseous substances. Particulate pollutants cover a size range from <10 nm to >100 pm. The major proportion of the aerosol below 1 pm is generally man-made, including sulfates from SO2 oxidation and carbon from vehicle exhausts, for example. Particles of a greater size are frequently natural (e.g., soil-derived, marine aerosol) but this division cannot be regarded as absolute. 

First, let us exclude now physical conversion and chemical reactions in the flowfleld (inert media). As an important example of such a flow the shock-tube problem studied numerically and experimentally can be mentioned. This problem is also considered below. 

The most common physical conversion processes are briquetting, pelletizing, and fiber extraction. Briquetting is the method used to convert loose biomass into high-density solid blocks, while during pelletization, the fine-particle raw material is compacted to pellet under pressure. Fiber extraction regards the extracting... 

In a cross section of the kiln, the rolling t3rpe of solids bed is assumed to be well mixed for heating up calculations and for kinetic calculations of relatively slow chemical or physical conversions in spite of the absence of relative motion in the stagnant part of the bed. This is justified because the Fourier time of a solids bed in commercial kilns is in the order of hours, while the cyclus time of a particle is in the order of seconds. Hence, bed heating occurs mainly by the continuous replacement of particles in the bed rather than by conduction. 

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