Specimen preparation method simple methods

Specimen preparation is simple, involving compressing a disc of the polymer sample for insertion in the instrument, and measurement time is usually less than for other methods, and X-rays interact with elements, i.e., the intensity measurement of a constituent element... 

Specimen preparation is simple, involving compressing a disc of the polymer sample for insertion in the instrument, measurement time is usually less than for other methods, and X-rays interact with elements as such, i.e., the intensity measurement of a constituent element is independent of its state of chemical combination. However, the technique does have some drawbacks, and these are evident in the measurement of cadmium and selenium. For example, absorption effects of other elements present, e.g., the carbon and... 

Apart from the short beam shear test, which measures the interlaminar shear properties, many different specimen geometry and loading configurations are available in the literature for the translaminar or in-plane strength measurements. These include the losipescu shear test, the 45°]5 tensile test, the [10°] off-axis tensile test, the rail-shear tests, the cross-beam sandwich test and the thin-walled tube torsion test. Since the state of shear stress in the test areas of the specimens is seldom pure or uniform in most of these techniques, the results obtained are likely to be inconsistent. In addition to the above shear tests, the transverse tension test is another simple popular method to assess the bond quality of bulk composites. Some of these methods are more widely used than others due to their simplicity in specimen preparation and data reduction methodology. 

Surface properties of mesoporous materials are sometimes important and TEM surface profile imaging is often used to investigate the surface structures of these materials. The advantages of this method are that it can be used to study the surfaces of small crystallites of almost any morphology, that the specimen preparation is as simple as that for the studies of bulk structures without requiring any special treatment and that, unlike scanning tunnelling... 

The specimen or specimens analyzed must be representative of the sample in the context of the study purpose or problem definition, particularly if the sample is heterogeneous. Sampling techniques that are inherently surface sensitive may not yield spectra that are characteristic of the bulk of the sample. Quantitative precision is likely to impose greater restrictions on the choice of the sample preparation method than simple generic fingerprinting studies, since reproducibility will be an essential requirement for most product quality assurance applications. 

Pure shear stresses are those which are imposed parallel to the bond and in its plane (Figure 11.1). Single-lap shear specimens do not represent pure shear, but are practical and relatively simple to prepare. They also provide reproducible, usable results. The preparation of this specimen and method of testing are described fully in ASTM D1002-01. Two types of panels for preparing multiple specimens are described. ... 

Wohler described a simple method for the preparation of boron nitride, which had been discovered by Balmain by melting boric acid with potassium cyanide. Wohler in 1828 just failed to discover vanadium in a Mexican lead mineral (see p. 153), and failed to anticipate H. Rose in discovering niobiiun in Bavarian tantalite and pyrochlor. He prepared a specimen of niobium pentoxide and sent it to Berzelius, who could not say if it was a new substance or not. ... 

Determination of Cell Constants, Crystal System, and Space Group. The requirements on specimen preparation are a bit less demanding when a powder pattern is used to determine the cell constants only as long as lines are not fully missing, because preferred orientation is so heavy. Unfortunately, an unknown unit cell cannot always be determined in this simple way. The method is most suitable for the cubic case. Squaring the Bragg equation gives ... 

Specimen preparation for TEM generally in-voles the formation of a thin film of the material less than 100 nm thick. The methods used for this preparation depend upon the nature of the polymer and its physical form. In the case of thick or bulk specimens, microtomy is generally used. In the case of solutions, powders or particulates, simpler methods can provide a thin, dispersed form of the material. Three types of simple preparations will be described later in this section dispersion, disintegration and film casting. The more complex methods such as microtomy, replication, etching and staining will be described in other sections of this chapter. 

Manual methods of freeze fracture are often useful in providing specimens for study in the SEM. An example of a freeze shattering method was described by Stoffer and Bone [406] for comparison with microtomy results. Polymers immersed in liquid nitrogen were mechanically shattered with a hammer, mounted, vacuum pumped and sputter coated for observation. This simple method is useful if the materials cannot be sectioned. However, fine structural details are not conclusive when specimens are prepared by such methods. 

The major structural unit of interest in emulsions, microemulsions, colloids and latexes is the particle. It is well known that the particle shape, size and distribution of a latex controls the properties and end use applications. Many latexes are manufactured with a controlled and sometimes monodisperse distribution of particle sizes. Polymer liquids, in the form of emulsions and adhesives, are wet and sticky, and therefore specimen preparation for electron microscopy is very difficxilt. As a result of the importance of the determination of particle size distribution, microscopy techniques have focused on specimen preparations which do not alter this distribution or which alter it as little as possible. Methods have included special cryotechniques (Section 4.9), staining-fixation methods (Section 4.4), microtomy (Section 4.3) and some simple methods (Section 4.1) such as dropping a solution onto a specimen holder. This section is meant to provide a brief survey of the types of microscopy applications which have been foimd useful in the evaluation of emulsions and latexes. 

The steps involved in the problem solving protocol are outlined in Table 7.1. They are rather simple and do not take much time to consider and such a protocol can save time in the long run. The protocol involves steps typical of scientific inquiry collect all the currently known facts, determine the nature of the problem, state the objective of the study, obtain the correct specimen, be sure to have experimental controls, look at the sample with the naked eye and then with a stereo microscope. These provide an aid to selection of the specific microscopy techniques and preparation methods needed to begin to address the objectives. The result should be that clearly defined analyses are conducted. 

LC—MS/MS assays for 25-OHD [27] are now commonplace in clinical laboratories, especially larger reference laboratories. Often, the first step in the analysis is a liquid—liquid extraction of nonpolar 25-OHD and a deuterated internal standard from serum into an organic solvent, followed by evaporative concentration and injection into the LC—MS/MS. Additional reported metirods for specimen preparation include manual and online solid-phase extraction and simple protein precipitation with an organic solvent. The advantages of LC—MS/MS assays over traditional radioimmimoassays and more current chemiluminescent immunoassays include the use of an isotope dilution for precise quantitation, as well as the ability to distinguish and separately quantitate 25-hydroxy vitamin D2 and 25-hydroxy vitamin D3. There is considerable controversy as to which method of 25-OHD quantitation is the best, however, since many large scale population studies on vitamin D, such as the Women s Health Initiative (WHl) and the National Health and Nutrition Examination Survey (NHANES), utilized radioimmunoassays [28]. 

---