Examination Techniques

Generally, for transmission examination, the sample thickness should not be more than 20 /tm. On the other hand, a sample that is too thin ( 1 /tm) yields absorption bands too weak to be detected. 

Liquid and gas samples do not need much preparation, but special cells to contain the samples are often necessary. The simplest method to prepare a liquid sample is to make a capillary thin film of the liquid. The capillary thin film is made by placing a drop of liquid on a KBr plate and sandwiching it with another KBr plate. This method, however, is not suitable for volatile liquids. Liquid cells can be used for volatile liquid and toxic liquid samples, particularly for quantitative analysis. The spacing between the bottom and the top of liquid cell is typically from 1 to 100 /u.m. The cell is made of an infrared-transparent material. Typically, KBr is used however, KBr should not be selected as the material for holding samples containing water because water dissolves KBr. Instead, ZeSe or AgCl should be used because they are infrared-transparent but not water soluble. Cells for gas samples are structurally similar to cells for liquid but the dimension is much larger. 

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Shear strength is measured via a simple single overlap shear specimen of standard dimensions (Fig. 9). In contrast to its simple appearance, the forces in a thin-adherend shear specimen can be quite complex due to the inherent offset loading of the specimen and subsequent bending in the substrates. The single overlap shear test is anything but a pure shear test, but the configuration is easy to manufacture, simple to test and is firmly entrenched in the industry as a primary examination technique for materials qualifications, inspection and process control. 

Substantial deposit-filled corrosion pits may result from the rapid concentration of only a few ppm of initial acid contaminant in the bulk water. The visual result can be similar to high pH pitting corrosion thus, more sophisticated examination techniques may be required to ensure that the true cause is properly identified. 

Visceral Fetal Examinations. The examination of the abdominal and thoracic viscera of fetuses is performed either fresh without fixation ( Staples technique ) or after Bouin s fixation by making freehand razor blade sections ( Wilson s technique Wilson, 1965). Both techniques have advantages. The fresh examination technique, which may require less training for thorough proficiency, provides a more easily interpreted view of heart anomalies. The examination must be performed on the day the dam is terminated, however, so having a large number of litters to examine in one day requires that a large team of workers be committed to the task. 

No matter how intrinsically interesting students find the study of organic chemistry, there will usually be one or more hurdles that need to be overcome, the examinations. Examination technique is undoubtedly a skill, and this chapter is aimed at developing such skills for organic chemistry. Throughout the book, we have tried to convince the reader that, by applying principles and deductive reasoning, we can reduce to a minimal level the amount of material that needs be committed to memory. 

Although MRA projection images may look much like classic DSA, they are based upon completely different facts. MRA provides a wide variety of examination techniques for different diagnostic purposes. Evaluation and interpretation require experience in the physical basics of the respective method in order to understand potentialities and limitations of MRA. It is particularly important to understand the origin of typical pitfalls and artifacts, which have been pointed out above. 

Draining of Consolidants Effect of Concentration. As noted in the introduction, one objective of the studies described here is to examine techniques for applying consolidants under conditions that will reduce the physical hazards to which the fabric substrate is exposed. Since the acrylic resins examined in Part II of this series (I) have outstanding resistance to degradation from UV light and heat and normally do not yellow or stiffen under adverse conditions, some of these resins were re-examined using a much less severe application technique. Milder curing procedures also were utilized. 

The current 4 epoch of liver research may later be known as biomolecular hepatology . Not only examination techniques based on biochemistry, histology and imaging, but also the therapy of liver disease will increasingly be determined by biomolecular research. 

All too often there is, unfortunately, a tendency to apply examination techniques on a broad and cost-intensive scale, and indeed irrationally . 

The impressive, almost 99% certainty of present-day liver diagnostics is the outcome of the coordination of all available examination techniques that have meanwhile been perfected - in conjunction with the further development of sensitive and specific procedures. 

The target of a detailed diagnosis is generally achieved using various and mutually complementary examination techniques. Diagnostic methods in liver disease are founded on four diagnostic pillars, which are applied stepwise and nearly always provide the basis for an exact and detailed diagnosis. Complex or invasive techniques are only used when they are clearly indicated. (19) (s. fig. 4.2)... 

It would be a tremendous loss if palpation and percussion of the liver and spleen were inadequately learned, inappropriately performed and no longer mastered as a basic examination technique for interpretative purposes on account of ultrasound methods. 

Sonographic artefacts may at times impede the assessment considerably. (47) Artefacts are mainly associated with the method applied and hence can often be eliminated simply by changing the examination technique. The occurrence of artefacts is largely fostered by extensive differences in acoustic impedance within a particular substrate, especially in the abdomen. In some 5% of cases, artefacts render sonographic examination impossible. They may appear in multiple forms ... 

In the case of suspected liver or biliary diseases, US is always indicated. Sonography has become a routine examination technique. (56, 75) (s. tab. 6.4)... 

We regard stasis in dilated bile ducts as a contraindication of biopsy, although there are controversial views in the literature concerning this point. (108, 151) The risk of biliary complications should not be underestimated, especially since new examination techniques have indeed... 

Laparoscopy is a low-risk instrumental examination technique for the abdominal cavity with a high degree of diagnostic relevance and low personnel input. 

Basically, the prioritization of methods within a diagnostic flow diagram should be determined by the question of whether (7.) use of an examination technique is indicated, (2.) indication applies at the given moment, and (5.) definitive diagnosis is likely to be obtained. Usually, only a definitive diagnosis allows statements to be made on therapy and prognosis ... 

Both the risks and the possibility of obtaining uncertain results are far greater with percutaneous biopsy than with laparoscopically directed biopsy. The latter produces a detailed diagnosis in 97-100% of cases, a result also confirmed by our own observations. (46, 90, 123, 129) Insufficient training in laparoscopy or the non-availability of this examination technique do not constitute an indication for percutaneous biopsy in liver cirrhosis, at least for initial diagnosis, (s. figs. 7.8, 7.15 16.5 28.13 35.2-35.4) (s. pp 160, 161, 408)... 

Tab. 37.11 Diagnostic parameters and examination techniques in cholangiocellular carcinoma...

Sonography In this biochemical constellation, sonography (also colour-encoded duplex sonography with visualization of the intrahepatic bile ducts) is the examination technique of choice, particularly when obstructive jaundice is suspected. There is evidence of prestenotically dilated bile ducts as well as, in some cases, accompanying strand-like, hyperechoic, infiltrating structures, which may be surrounded by a hypo-echoic margin. The tumour itself can be identified in most cases, particularly when it is localized in the liver hilum. 

We have made equal volume batch extraction measurements on synthetic high sodium concentration waste using 20 volume % DHDECMP in 2 1 decalin-DIPB. Only actinides and a few chemical constituents were examined. Techniques were as described in the above section. Extraction data are shown in Table V. 

Raman spectroscopy is attractive as an examination technique for ceramic and polymeric materials because it can simply examine them by illuminating their surfaces regardless of sample thickness and form. Raman microscopy is even more attractive because it can examine a microscopic area with diameters in the order of 1 /xm. Raman microscopy is increasingly used for materials characterization, including ... 

For surface structure studies, perhaps the most popular technique has been LEED (373). Elastically diffracted electrons from a monoenergetic beam directed to a single-crystal surface reveal structural properties of the surface that may differ from those of the bulk. Some applications of LEED to electrocatalyst characterization were cited in Section IV (106,148,386). Other, less specific, but valuable surface examination techniques, such as scanning electron microscopy (SEM) and X-ray microprobe analysis, have not been used in electrocatalytic studies. They could provide information on surface changes caused by reaction, some of which may lead to catalyst deactivation (256,257). Since these techniques use an electron beam, they can be coupled with previously discussed methods (e.g. AES or XPS) to obtain a qualitative mapping of the structure and composition of a catalytic surface. 

Fibers of the control and selected chemically modified cottons were examined techniques of optical microscopy described previously.Ultra thin cross sections of the fibers were subjected to layer expansion by polymerization of methyl methacrylate and to solubility tests in 0.5 M cupriethylenediamine (cuene) and were examined by the techniques of transmission electron microscopy as previously reported.Scanning electron micrographs of fibers of selected samples before and after subjection to various solvents were also obtained. 

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