Cell-size test methods

BS 1335 1968, Air Depolarized Primary Cells -Dimensions of Containers. Dimensions, materials of electrodes for dry, wet, inert cells and batteries. Details of electi olyte for wet cells, Performance, test methods. 20 page A5 size. Gr 4 ( 10.50). 

It is necessary to estabUsh a criterion for microbial death when considering a sterilization process. With respect to the individual cell, the irreversible cessation of all vital functions such as growth, reproduction, and in the case of vimses, inabiUty to attach and infect, is a most suitable criterion. On a practical level, it is necessary to estabUsh test criteria that permit a conclusion without having to observe individual microbial cells. The failure to reproduce in a suitable medium after incubation at optimum conditions for some acceptable time period is traditionally accepted as satisfactory proof of microbial death and, consequentiy, stetihty. The appHcation of such a testing method is, for practical purposes, however, not considered possible. The cultured article caimot be retrieved for subsequent use and the size of many items totally precludes practical culturing techniques. In order to design acceptable test procedures, the kinetics and thermodynamics of the sterilization process must be understood. 

In l02) the authors describe the design of an experimental plant for studies of acoustic cavitation in flowable high polymers with the help of optic methods the plant employs a flat-slit transprent-wall capillary acoustic treatment of a polymer was carried out at a frequency of 17.8 kHz, and amplitude of vibration between 0 and 15 mcm. The study was conducted on 1,2 polybutadienes of narrow molecular-mass distribution tests were arranged at room temperature. It has been demonstrated that static mechanical stresses occur in a stationary (non-flowing) polymer under the action of acoustic treatment isochrome lines in the viscosimetric tank form a cellular structure with cell size of about 1-3 mm, and in the capillary the isochromes are observed in form of longitudinal strips (Fig. 19). The authors have also found that acoustic... 

The discovery of x-rays provided crystallographers a powerful tool for the thorough determination of crystal structures and unit cell sizes [20-26], X-rays have wavelengths between 0.2 and 10 nm. As x-rays possess dimensions comparable to the interplanar distances in crystals, x-ray crystallography is an ideal nondestructive method for material characterization, since nanometer parameters as well as macroscopic properties of the tested samples can be determined from x-ray diffraction data. 

Through a series of round robin tests conducted by participating laboratories, ASTM Committee D-32 on Catalysts has characterized a variety of catalyst materials using standard test methods. Materials include fluid cracking catalysts, zeolites, silicas, aluminas, supported metals, and a gas oil feedstock. Properties characterized include surface area, crush strength, catalytic microactivity, particle size, unit cell dimensions and metal content. These materials are available from the National Institute of Standards and Technology as reference materials. 

ASTM Test Methods D 2842 on water absorption and D 2856 on open-cell content require knowledge of surface cell volume, which uses cell-size values in the calculation. 

ASTM D 3576-77 Standard Test Method for Cell Size of Rigid Cellular Plastics, 4 pp (Comm D-20)... 

Surface areas of catalysts were determined by N2 adsorption using an ASAP 2000 analyzer from Micromeritics. Matrix and zeolite surface areas were calculated by the t-plot method accordingly to the ASTM-D-4365 standard test [11]. Zeolite unit cell size (UCS) was determined by X-Ray diffraction using a SIEMENS D-500 automated analyzer according to the ASTM-D-3942-80 standard [11]. 

This preparation method of catalyst array has an advantage, which is that the high surface-area catalysts can be screened under similar circumstances as are used in the traditional half-cell electrochemical testing. An additional advantage is that through this approach, the effect of other chemical/physical variables besides composition can also be studied, for example, variables such as Pt loading and catalyst particle size, as has been done in Guerin s work. 

That method involves the use of particles of known size, e.g. latex beads, bacterial cells and/or macromolecules, in order to quantify the effective pore size of a filter material. It may be, however, that a recently formed CEN committee (CEN/TC 272 Metrology of microfiltration or ultrafiltration membranes (Test Methods and Terminology) ) may render further B.S.I. work on Parts 3 and 4 unnecessary. 

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