Microscopic techniques, evidence investigation

Some investigators have found the enzyme primarily in the 100,000 X g supernatant fluid of extracts of rabbit brain (37), dog heart (42), rat liver (45), rat brain, and beef pineal gland (48). In contrast, other investigators have reported that the enzyme from beef heart (36) and rat brain (49, 50) is mostly particulate being present in all the primary fractions nuclear, mitochondrial, microsomal, and 100,000 X 9 supernatant. The reasons for these discrepancies are not entirely clear but most likely result from differences in fractionation technique. Evidence from density gradient procedures coupled with electron microscopic examination indicate that the enzyme is preferentially located at nerve... 

The analysis of the above techniques (Section 3.4.2.2) developed to estimate the conditions under which stable CBF and NBF exist, and reveals the equilibrium character of the transition between them and the particular features of the two types of black films. Furthermore the difference between the techniques of investigation as well as the difference between their intrinsic characteristics proves to be a valuable source of information of these thinnest liquid formations. The transition theory of microscopic films evidences the existence of metastable black films. Due to the deformation of the diffuse electric layer of the CBF, the electrostatic component of disjoining pressure 1 L( appears and when it becomes equal to the capillary pressure plus Ylvw, the film is in equilibrium (in the case of DLVO-forces). As it is shown in Section 3.4.2.3, CBF exhibit several deviations from the DLVO-theory. The experimentally obtained value of ntheoretically calculated. This is valid also for the experimental dependence CeiiCr(r). Systematic divergences from the DLVO-theory are found also for the h(CeiXr) dependence of NaDoS microscopic films at thickness less than 20 nm. 

This chapter discusses the role of microscopic analysis for investigating all the above mentioned (i) - (iii) aspects, presenting a rationalized overview of available results. As it is of increasing evidence that only a multidisciplinary approach can lead to a more accurate picture of a NR-based composite, the information brought about by microscopic analysis is also discussed as complementary to findings arising from other analytical techniques. 

During the past two decades, sophisticated microscopic and spectroscopic techniques have been aj lied to the investigation of sintering and redispersion of model film and single crystal metal-support systems. This review presents and discusses results obtained in these investigations with an emphasis on mechanistic evidence. 

In diagnostic clinical medicine, DNA identification has been applied to investigations of patient tissue specimens obtained during biopsies or autopsies. Because of imaginative adaptations of DNA extraction techniques, the DNA contained in slides and preserved tissue specimens can now be investigated for evidence of infectious or genetic diseases. For example, in situ DNA hybridization is an ultrasensitive technique in which specific DNA probes are applied directly to tissue embedded in paraffin. (Paraffin-embedded tissue specimens are used in microscopic studies. Such slides can be stored... 

This case example serves to illustrate several points first, that forensic microscopy should be applied as an early line of examination rather than a late one. The above case is a prime example of an examination in which an investigative, rather than comparative, approach may have likely led to an earlier resolution of a serial murder case. Second, the scientific approach pursued in each case involving the microscopic examination of trace evidence may be different. Thus, the forensic microscopist must be a true scientist who is able to adapt the techniques and methods available to the requirements of the case at hand and not be bound to a standardized procedure devised for the use of technicians. 

Successful forensic trace evidence analysis is characterized by the ability to locate, collect, manipulate, identify, and compare microscopic particles. However, sample poverty is common in legal investigations. The sample size is frequently limited, and oftentimes only a portion of the sample can be used, pending the need for additional analysis. This places a further burden on the analyst, techniques, or instruments used. Accordingly, microscopy is the first choice for most forensic examinations. 

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