Material comparison standards

Material comparison standards, which are usually samples of the materials imder examirration and provide limiting or target values. 

Rossbach M, Ostapczuk P, Emons H (1998) Microhomogeneity of candidate reference materials Comparison of solid sampling Zeeman-AAS with INAA. Fresenius J Anal Chem 360 380-383. Rossbach M, Stoeppler M (1987) Use of CRMs as mutual calibration materials and control of synthetic multielement standards as used in INAA. J Radioanal Nud Chem Artides 113 217-223. Sargent M (1995) Development and application of a protocol for quality assurance of trace analysis. Anal Proc 32 71-76. 

Comparison of test values with a conventional true value ( reference value ) of a (certified) reference material (RM, CRM). In method development and validation of analytical procedures, the comparison of experimental results with standards of diverse kind (laboratory standards, certified reference materials, primary standards) plays an essential role. The decision as to whether an experimental result hits the reference value depends not only from the result itself but also from its uncertainty interval. 

Key words Traceability chain Metrology in chemistry Reference material Comparisons values of standards... 

CDC anticipated two problems with providing trace-ability to clinical laboratories. First, matrix effects limit the use of processed serum-based reference materials in standardization. One solution is to use fresh serum specimens for accuracy transfer and method comparisons. Second, CDC realized it could not standardize an esti-... 

In conclusion, though ASTM D 1413 is generally useful for a comparison of WPC materials with standard wood samples, it does not predict actual resistance of composite materials with respect to microbial degradation in the real world. 

Recovery and Its Uncertainty. The trueness of the method must be considered in the calculation of the uncertainty estimate to cover uncertainties due to method bias. Barwick and Ellison describe several possibilities for estimating uncertainty related to trueness, including the use of data from the analysis of a representative certified reference material, comparison with a reference or standard method, and spiking recovery studies. Since no representative certified reference material was available for this analyte-matrix combination, the trueness was estimated using spiking studies. As stated in the previous section, the spiked samples in this example were assumed to be representative of the incurred tissue. 

XRD analysis provides a means by which different crystalline phases are characterized and identified. Samples are normally prepared as finely ground material and then presented to the X-ray beam in such a way that individual crystallites are randomly orientated. Comparison of diffraction traces with standard reference profiles enables the identification of phases to be made. Reference patterns are published by the International Centre for Diffraction Data. In some cases with a careful use of reference materials, internal standards and mass absorption corrections, some quantitative results are obtainable using a variety of mathematical formulas on the peak heights or areas. 

Commonly used standards in the United States are Tyler screens and US Standard screens (American Society for Testing and Materials). Similar standards in the United Kingdom are British Standard screens and Institute of Mining and Metallurgy (IMM) screens. The dimensions of the screens are widely published and it is a simple matter to assemble PSD curves such as those in Rgs 7.13 and 7.14. A recent correlation mathematizing all these standards may still be useful for drawing comparisons [34]. The correlating equation takes the form... 

The effectiveness of flame retardant additives can be ascertained by a wide variety of methods. Some are only appropriate for laboratory comparisons between materials, whereas standard fire tests are designed to give regulatory approval. 

The overall activity of a transporter is influenced by numerous parameters, which include buffer and membrane composition, membrane polarization, and osmotic stress, to name only a few. The comparison of the intrinsic activity of different transporters on an absolute scale is nearly impossible for this reason. This is not further problematic because absolute activities are probably the least interesting aspect of synthetic transport systems and arguably deserve little priority. What really matters is responsiveness to specific chemical or physical stimuh. This includes sensitivity toward membrane composition, membrane potential, pH, anions, cations, molecular recognition, molecular transformation (catalysis), or light. These stimuli-responsive, multifunctional, or smart transport systems are attractive for use in biological, medicinal, and materials sciences. Standard techniques to identify such unique characteristics rather than absolute activities or mechanistic details are outlined in this section. 

In an attempt to marry the best characteristics of HTCC and LTCC, Kyocera has developed an intermediate-firing cofired ceramic, designated as A0600. This alumina material employs copper-based conductors. Thus, this composition enjoys the low electrical resistivity of Cu metallization along with the superior mechanical and thermal properties of alumina. A "broad-brush" comparison of this material to standard 92% alumina and a generic LTCC formulation is presented in Table 6.4. 

Compilation and direct comparison of the natural data from Stirling et cd. [61] and Weyer et al. [62] require care, since each group used a different reference material as standard. Stirling et al. [61] reported their data in terms of epsilon units, with e 5/238u X... 

The wall thicknesses of the aluminum molds are very thick in comparison to the thin-walled sheet steel molds (1.5 to 3 mm). Wall thicknesses between 7 and 15 mm are used for casting molds (depending on the quality of the casting process). In the mold shells that are CNC milled out of an aluminum block material, a standardized wall thickness of 7 mm is established. 

A true material comparison is possible only when property values are determined by identical test methods under identical conditions (1). Generally speaking, physical and electrical properties of plastics and electrical insulating materials are affected by temperature and humidity. Plastic materials tested above room temperature will yield relatively higher impact strength and lower tensile strength and modulus. High humidity tends to alter the electrical property test results. Obviously, in order to make reliable comparisons of different materials and test results obtained by different laboratories, it is necessary to establish standard conditions of temperature and humidity. 

The DSC analysis of both the materials when submitted to the LOW cycle show a lack of cute that can be seen in the figures as an endothermic (residual heat) peak. While STANDARD cured samples of Material B clearly show a residual heat of cure, such evidence is not so clear for DSC traces of material A-STANDARD cured. In fact the presence of an incomplete cure could be seen in the A-STANDARD case only by comparison of its DSC trace with the A-HIGH DSC plot. The HIGH cycle... 

K. M. Sappenfield, G. Marinenko, and J. L. Hague, Standard Reference Materials Comparison of Redox Standards, NBS Special Publication 260-24, U.S. Government Printing Office, Washington, D. C. (1972). 

The comparison plot (cf. Section 2.10) is a simple plot of the uptake per unit mass of the experimental material against that of a reference sample at the same relative pressure. It may be regarded as an alternative to the a,-plot, in which the abscissae are actual adsorptions on a sample arbitrarily taken as a standard. 

Physical or artifactual standards are used for comparison, caUbration, etc, eg, the national standards of mass, length, and time maintained by the National Institute of Standards and Technology (NIST) or the standard reference materials (SRMs) collected and distributed by NIST. Choice of the standard is determined by the property it is supposed to define, its ease of measurement, its stabiUty with time, and other factors (see Fine chemicals). 

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