Specimen standardization

Simplest method of diagnosis is detection of oocysts by modified acid-fast staining of a stool specimen. Standard ova and parasite test does not include Cryptosporidium. 

A number of potential users, such as the printing industry, are interested in the solvent fastness not only of a pigment but of an entire pigment-vehicle system. Standardized tests are available. A proof print of a certain size is placed inside a test tube and allowed to remain in the target solvent at 20°C for 5 minutes. The change in solvent color is determined and the print dried and compared with an untreated specimen. Standard solvents [14] are ethanol or the following mixture ... 

Heat Deflection Temperature - The temperature at which a material specimen (standard bar) is deflected by a certain degree under specified load. Also called rensi/e heat distortion temperature, heat distortion temperature, HDT, deflection temperature under load. 

In order to produce truly comparable data, use of uniform standards, uniform test specimens, standard molds, narrow specimen molding conditions specifically defined for each resin family, and uniform test conditions, that is, identical, reproducible conditions is vital. Simply providing detailed information about the specimen geometry, preparation, conditioning, and test procedure is not sufficient to allow true comparability. 

Standard Practice for Making and Using C-Ring Stress-Corrosion Test Specimens Standard Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Specimens Standard Practice for Determining Cracking Susceptibility of Metals Exposed Under Stress to a Hot Salt Environment... 

Table 1. Four point bending strength, fracture toughness measured by single edge pre cracked beam (SEPB) method, and Vickers hardness of the tested alumina specimens. Standard deviations are in brackets.

The radiation and temperature dependent mechanical properties of viscoelastic materials (modulus and loss) are of great interest throughout the plastics, polymer, and rubber from initial design to routine production. There are a number of laboratory research instruments are available to determine these properties. All these hardness tests conducted on polymeric materials involve the penetration of the sample under consideration by loaded spheres or other geometric shapes [1]. Most of these tests are to some extent arbitrary because the penetration of an indenter into viscoelastic material increases with time. For example, standard durometer test (the "Shore A") is widely used to measure the static "hardness" or resistance to indentation. However, it does not measure basic material properties, and its results depend on the specimen geometry (it is difficult to make available the identity of the initial position of the devices on cylinder or spherical surfaces while measuring) and test conditions, and some arbitrary time must be selected to compare different materials. 

Calibration procedure bases on rope specimens and corresponds to the Standard Pratice ASTM 1574. It takes a piece of the rope under test having a nominal metallic cross-section area (LMA=0) to set zero point of the instrument. Rope section with the LMA value known is used to set the second point of LMA calibration charactiristics. It is possible to use the air point calibration when there is no rope in a magnetic head (LMA=100%). 

The specimens have been cleaned according to the NFA 09.521 standard, dried at ambient temperature 5 minutes, immerged 10 minutes in the penetrant and hung up 10 minutes. The excess penetrant has been removed at the washing unit. The developer has been applied immediately after the drying, and the indications examination has been performed 5, 10 and 20 minutes after the developer application. 

ProcGen generates a scaled 3D model of the test specimen geometry, in the form of a faceted boundary representation. This model is made available for use by other software tasks in the system. The STEP file format (the ISO standard for product data exchange) was chosen to provide future compatibility with CAD models produced externally. In particular part 204 (faceted b-rep) of this standard is used. 

F — B ) is the ratio of the reflective echo height F from the contact surface to the standard reflective echo height B on the bottom of the upper specimen. Hereafter, F/B is called the echo height. Moreover, the contact surface of this lower specimen have no V defect. In the frequency, O is... 

Interplanar Spacings. Diffractometer alignment procedures require the use of a well-prepared polycrystalline specimen. Two standard samples found to be suitable are silicon and a-quartz (including Novaculite). The 26 values of several of the most intense reflections for these materials are listed in Table 7.6 (Tables of Interplanar Spacings d vs. Diffraction Angle 26 for Selected Targets, Picker Nuclear, White Plains, N.Y., 1966). To convert to d for Ka or to d for Ka2, multiply the tabulated d value (Table 7.6) for Ka by the factor given below ... 

The number and kind of defects in a given specimen, as well as the crystal habit and with it the proportion of different crystal faces exposed, will in general depend in considerable degree on the details of preparation. The production of a standard sample of a given chemical substance, having reproducible adsorptive behaviour, remains therefore as much an art as a science. 

An interesting example of a large specific surface which is wholly external in nature is provided by a dispersed aerosol composed of fine particles free of cracks and fissures. As soon as the aerosol settles out, of course, its particles come into contact with one another and form aggregates but if the particles are spherical, more particularly if the material is hard, the particle-to-particle contacts will be very small in area the interparticulate junctions will then be so weak that many of them will become broken apart during mechanical handling, or be prized open by the film of adsorbate during an adsorption experiment. In favourable cases the flocculated specimen may have so open a structure that it behaves, as far as its adsorptive properties are concerned, as a completely non-porous material. Solids of this kind are of importance because of their relevance to standard adsorption isotherms (cf. Section 2.12) which play a fundamental role in procedures for the evaluation of specific surface area and pore size distribution by adsorption methods. 

Fig. 2. Illustrations of forces to which adhesive bonds are subjected, (a) A standard lap shear specimen where the black area shows the adhesive. The adherends are usually 25 mm wide and the lap area is 312.5 mm. The arrows show the direction of the normal apphcation of load, (b) A peel test where the loading configuration, shown by the arrows, is for a 180° peel test, (c) A double cantilever beam test specimen used in the evaluation of the resistance to crack propagation of an adhesive. The normal application of load is shown by the arrows. This load is appHed by a tensile testing machine or other...

Film and sheeting materials test methods have been standardized by ASTM, DIN, and others. As with all materials, the test specimens must be carefiiUy prepared and conditioned. Thin-film specimens are vulnerable to nicks and tears which mar the results. Moisture and temperature can affect some materials. Common test methods are Hsted in Table 1. 

United States Pharmacopeia. Reference standards are requited in many USP and NF tests, and in a few FCC tests. The USPC distributes such standards domestically and has authorized international distribution by a number of organizations or companies. There are well over 1000 USP Reference Standards, including several for melting points, and also specimens of narcotics and other controlled substances. New standards are constantly under development as needed in various USP, NF, and FCC testing methods. 

Specific Tests. Federal (United States) Motor Vehicle Safety Standard (MVSS) 302 is used to measure the burning behavior of materials used in automobile interiors. A specimen is mounted horizontally and ignited for 15 seconds. The burning rate should be below 10 cm /min. The test specimen is 35.5 X 10.1 cm by the actual thickness (up to 1.3 cm). Automakers typically impose more severe criteria than the 10 cm /min in the standard. 

Blood and urine are most often analyzed for alcohol by headspace gas chromatography (qv) using an internal standard, eg, 1-propanol. Assays are straightforward and lend themselves to automation (see Automated instrumentation). Urine samples are collected as a voided specimen, ie, subjects must void their bladders, wait about 20 minutes, and then provide the urine sample. Voided urine samples provide the most accurate deterrnination of blood alcohol concentrations. Voided urine alcohol concentrations are divided by a factor of 1.3 to determine the equivalent blood alcohol concentration. The 1.3 value is used because urine has approximately one-third more water in it than blood and, at equiUbrium, there is about one-third more alcohol in the urine as in the blood. 

The Vickers hardness test is commonly made on a flat specimen on which the indenter is hydrauhcaHy loaded. When the desired number of indentations have been made, the specimen is removed and both diagonals of the indentations, measured using a caUbrated microscope, are then averaged. The Vickers hardness number may be calculated, or for standard loads taken from a precalculated table of indentation size vs VHN. The preferred procedures are described in ASTM E92 (2). 

Test Methodfor Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method, ASTM C423-90a, ASTM, Philadelphia, Pa., 1990. Standard Practices for Mounting Test Specimens During Sound Absorption Tests, ASTM E795-92, ASTM, Philadelphia, Pa., 1992. 

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