Specimen and Instrumentation

The integrated intensity is a function of the atomic structure and it also depends on multiple factors, such as certain specimen and instrumental parameters. Considering Eq. 2.19 and after including necessary details, earlier grouped as geometrical effects, the calculated integrated intensity in powder diffraction is expressed as the following product ... 

The presence of symmetry (Chapter 1) coupled with well-defined analytical relationships determining both the directions and intensities of scattered beams (Chapter 2), in addition to known properties of both the specimen and instrument employed to obtain a powder diffraction pattern (Chapter 3), makes it possible to develop both the general methodology and algorithm(s) suitable for automation. Given the amount of numerical data collected in a typical powder diffraction experiment, their interpretation and processing usually involves a broad use of computers. 

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 infonuation that can be extracted from inorganic samples depends mainly on tlie electron beam/specimen interaction and instrumental parameters [1], in contrast to organic and biological materials, where it depends strongly on specimen preparation. 

The diagnostics applied to shock experiments can be characterized as either prompt or delayed. Prompt instrumentation measures shock velocity, particle velocity, stress history, or temperature during the initial few shock transits of the specimen, and leads to the basic equation of state information on the specimen material. Delayed instrumentation includes optical photography and flash X-rays of shock-compression events, as well as post-mortem examinations of shock-produced craters and soft-recovered debris material. 

An ASTM recommended practice (A Standard Reference Method for Making Potentiostatic and Potentiodynamic Anodic Polarisation Measurements, G5 1972) has been issued. It provides a means of checking experimental technique and instrumentation using a specimen from a single heat of AISI Type 430 stainless steel, which is available from ASTM. ... 

Methods employed to determine the impact resistance of plastics include pendulum methods (Izod, Charpy, tensile impact, falling dart, Gardner, Dynatup, etc.) and instrumented techniques. In the case of the Izod test, what is measured is the energy required to break a test specimen transversely struck (the test can be done either with the specimen notched or unnotched). The tensile impact test has a bar loaded in tension and the striking force tends to elongate the bar (Chapter 5, Impact Strength). 

The labor-intensive nature of polymer tensile and flexure tests makes them logical candidates for automation. We have developed a fully automated instrument for performing these tests on rigid materials. The instrument is comprised of an Instron universal tester, a Zymark laboratory robot, a Digital Equipment Corporation minicomputer, and custom-made accessories to manipulate the specimens and measure their dimensions automatically. Our system allows us to determine the tensile or flexural properties of over one hundred specimens without human intervention, and it has significantly improved the productivity of our laboratory. This paper describes the structure and performance of our system, and it compares the relative costs of manual versus automated testing. 

Figure 7, therefore, illustrates several practical methods of sampling. First, the sampling of a relatively large initial volume (10 pi ). This has the advantage that it can be measured with precision by the particular instrument employed second, the removal of protein from the specimen, and, third, the taking of aliquots so that smaller volumes of sample can be removed with the same accuracy with which the initial sample was measured. 

A typical instrument is equipped with four computer controlled crystal spectrometers, as well as an EDS system for preliminary qualitative analysis. A light microscope is provided for examining the specimen and also for ensuring that the specimen height is adjusted until it is on the Rowland circle. The drawing of... 

The specimen must have a conducting surface, so that non-conducting specimens must therefore be coated before being placed in the instrument. Since the coating will itself absorb X-rays as they are emitted from the specimen, and it will also emit its own characteristic X-rays, it should be as thin as possible and be of low atomic... 

The use of a STEM instrument allows the controlled movement of a very fine electron beam in relation to the specimen and the efficient detection of the scattering and energy losses of the beam. We have outlined here a few of the possible applications arising from this capability. Other applications, of increasing sophistication and power will undoubtedly follow in time. In particular a range of phenomena, resulting from coherent interference effects in diffraction patterns produced by coherent convergent beams, have been observed (26) but not yet exploited. 

Particular techniques and instruments may, of course, be required for special purposes for instance the preparation of specimens for specific examination (for example, metallographic examination) and tests of their polishing, cutting, drawing, rolling, etc. 

The instmment shown in Figure 2.4 is a double-axis instrument. The first axis is the adjustment of the beam conditioner, the second is the scan of the specimen through the Bragg angle. It is irrelevant to this definition that a practical diffractometer may contain a dozen or more controlled axes , for example, to tune and to align the beam conditioner, to locate the specimen in the beam, to align and to scan the specimen and to control shts. It is the differential movement of the two main axes that make the measnrement and determine the precision and accuracy of the instrument. This is the basic high resolntion diffractometer, which is now widely nsed for measniements of crystal perfection, epilayer composition and thickness. 

Three areas of methodolc stressed here are of special concern for the study of air pollution effects on v etation growth of the test organisms, exposure facilities, and instrumentation. First, to determine the effects of air pollutants on many plant species, one must have a good understanding of the best cultural conditions for a given test crop some results reflect the use of poor test specimens. Second, dynamic... 

Compression Test. Compression tests similar to that described in (5) were conducted for yield stress C and modulus E measurement. Rectangular neat resin specimens (1.27 cm x 1.27 cm x 2.54 cm) cut from the cast resin plates were tested under compression, as shown in Figure 1, in an universal testing machine at a loading rate of 0.05 cm/min. For each resin system studied, tests were conducted at several temperature levels between -60 and 60 degree C. All specimens were instrumented with strain gages for... 

Analysis methods for hydrogen absorbed in the deposit have been described (65), and instruments are commercially available to detect hydrogen in metals. Several working tests have been devised that put plated specimens under strain and measure the time to failure. A method for cadmium-plated work has been described (66) as has a mechanical test method for evaluating treatments on AISI 4340 Steel (67). Additional information on testing for hydrogen embrittlement is also available (68). 

Fluorescence microspectrophotometry typically provides chemical information in three modes spectral characterization, constituent mapping in specimens, and kinetic measurements of enzyme systems or photobleaching. All three approaches assist in defining chemical composition and properties in situ and one or all may be incorporated into modem instruments. Software control of monochrometers allows precise analysis of absoiption and/or fluorescence emission characteristics in foods, and routine detailed spectral analysis of large numbers of food elements (e.g., cells, fibers, fat droplets, protein bodies, crystals, etc.) is accomplished easily. The limit to the number of applications is really only that which is imposed by the imagination - there are quite incredible numbers of reagents which are capable of selective fluorescence tagging of food components, and their application is as diverse as the variety of problems in the research laboratory. 

An unstable crack is primarily driven by the elastic energy already stored in the specimen (and not so much by the energy introduced into the specimen by the continued deformation). A pertinent experiment was carried out by Stalder [30], who investigated the impact fracture of PMMA using an instrumented hammer nose and standard notched Charpy specimens with sprayed-on graphite strain gages. With this double-instrumentation technique... 

Correction of 100 peak of PET 06 specimen for instrumental broadening by Stokes method and by Jones method... 

Aitio, A. and Jarvisalo, J. (1994) Sampling and sample storage. In Techniques and Instrumentation in Analytical Chemistry, Vol. 15, Trace Element Analysis in Biological Specimens (eds Herber, R.F.M. and Stoeppler, M.). Elsevier, Amsterdam. 

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