Direct Examination

However, contrary to the initial premise stated above, most polymeric samples, and particularly those of technological or commercial importance, do not naturally tend to occur in the form of a 50 nm-thick film. For bulk samples to be made amenable to examination by TEM they must therefore be subjected to some initial sample-preparation procedure. Indeed, the problems of sample geometry, beam sensitivity and intrinsically low contrast described above are such that they are often best overcome by the indirect examination of the sample. TEM techniques may therefore be divided into those in which the sample is examined directly and those in which a less direct approach is adopted, 

With recent advances in instrument control and digital image acquisition and processing, new possibilities are beginning to appear for the TEM of beam-sensitive samples. One fundamental disadvantage of conventional 

Another type of multi-beam technique that has been employed extensively to study less beam-sensitive materials is so-called lattice imaging. To produce an image where periodicities of less than 1 nm can be resolved necessarily requires high magnifications and an intense, concentrated beam, i.e. conditions not conducive to long lifetimes in beam-sensitive materials. Nevertheless, despite the difficulty of the approach, lattice imaging has been attempted in a number of polymer systems [116-119]. 

Clinical specimens obtained for the recovery of dematiaceous fungi usually do not require extensive processing. If aspirated specimens contain a substantial amount of purulent material, this can be dissolved with N-acetyl-L-cysteine without sodium hydroxide. Tissue specimens and biopsy material should be homogenized in a tissue homogenizer after highly suspicious areas consisting of necrotic, purulent, or caseous material are selectively examined microscopically and inoculated onto isolation media. 

Most mycologists consider it fruitless to directly examine clinical specimens for the yeast form of Sporothrix schenckii. The number of yeast cells in the specimen is typically very limited, and their small size and shape are not distinctive. The yeast form of S. schenckii is not easily seen in sections of tissue stained with hematoxylin and eosin. 

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Relaxation kinetics may be monitored in transient studies tlirough a variety of metliods, usually involving some fonn of spectroscopy. Transient teclmiques and spectrophotometry are combined in time resolved spectroscopy to provide botli tire stmctural infonnation from spectral measurements and tire dynamical infonnation from kinetic measurements that are generally needed to characterize tire mechanisms of relaxation processes. The presence and nature of kinetic intennediates, metastable chemical or physical states not present at equilibrium, may be directly examined in tliis way. 

Membrane Cliaraeterization MF membranes are rated bvtliix and pore size. Microfiltration membranes are imiqiielv testable bv direct examination, but since the number of pores that rnav be obsen ed directlv bv microscope is so small, microscopic pore size determination is rnainlv useful for membrane research and verification of other pore-size-determining methods. Furthermore, the most critical dimension rnav not be obseiA able from the surface. Few MF membranes have neat, cvlindrical pores. Indirect means of measurement are generallv superior. Accurate characterization of MF membranes is a continuing research topic for which interested parties should consult the current literature. 

Our immediate and instinctive reaction to an impact or explosion leaves a mental image of utter chaos and destruction. There may be a fascination with the power of such events, but our limited time resolution and limited pressure-sensing abilities cannot provide direct information on the underlying orderly mechanical, physical, and chemical processes. As with other phenomena not subject to direct examination by our human senses, the scientific descriptions of shock and explosion phenomena rest upon a collection of images of the processes which are derived from a range of experiences. The three principal sources of these images in shock science—experiment, theory, and numerical simulation—are indicated in the cartoon of Fig. 3.1. 

Can one further enhance the performance of this classically promoted Rh catalyst by using electrochemical promotion The promoted Rh catalyst, is, after all, already deposited on YSZ and one can directly examine what additional effect may have the application of an external voltage UWR ( 1 V) and the concomitant supply (+1 V) or removal (-1 V) of O2 to or from the promoted Rh surface. The result is shown in Fig. 2.3 with the curves labeled electrochemical promotion of a promoted catalyst . It is clear that positive potentials, i.e. supply of O2 to the catalyst surface, further enhances its performance. The light-off temperature is further decreased and the selectivity is further enhanced. Why This we will see in subsequent chapters when we examine the effect of catalyst potential UWR on the chemisorptive bond strength of various adsorbates, such as NO, N, CO and O. But the fact is that positive potentials (+1V) can further significantly enhance the performance of an already promoted catalyst. So one can electrochemically promote an already classically promoted catalyst. 

This allows for direct examination of the effect of promoter coverage and of O on the catalytic reaction kinetics. Such examples are shown in Figures 6.314 17 and 6.419"22 for the four main types of experimentally observed catalytic rate, r, vs work function, dependence, i.e. 

When tubulin heterodimers are assembled into microtubules, they form linear protofilaments with the P-tubulin subunit of one tubulin molecule linking covalently with the a-subunit of the next. Direct examination by electron microscopy of tannic acid-treated specimens has shown that micrombules in neurons and the A-microtubules of cilia and flagella have 13 protofilaments arranged side to side to form a cylinder around what appears to be an empty lumen. 

Studies in chemistry or any realm of science commonly consist of a series of directed examinations of parts of nature s realm called systems. A system is an identifiable fragment of the world that is recognizable and that has attributes that one can identify in terms of form and/or function. We can give examples at any level of size and complexity and in essentially any context. Indeed, a dog is a system at a pet show whereas the human heart is a system to the cardiologist a tumor cell is a system to the cancer specialist a star or planet or galaxy is a system to an astronomer a molecule or a collection of molecules is a system to a chemist and an atom or group of atoms is a system to a physicist. A system is, then, whatever we focus our attention upon for study and examination. 

Microbiologic studies that allow for direct examination of a specimen (e.g., sputum, blood, or urine) also may aid in a presumptive diagnosis and give an indication of the characteristics of the infecting organism. Generally, microbial cultures are obtained with a Gram stain of the cultured material. 

Ideally, lumbar puncture to obtain cerebrospinal fluid (CSF) for direct examination and laboratory analysis, as well as blood cultures and other relevant cultures, should be obtained before initiation of antimicrobial therapy. However, initiation of antimicrobial therapy should not be delayed if a pretreatment lumbar puncture cannot be performed. 

Endoscopy A procedure used to evaluate the interior surfaces of an organ by inserting a small scope into the body through it, one can directly examine almost any part of the intestinal tract. Biopsies can be obtained, polyps removed, and clear images obtained. 

Applications X-ray fluorescence is widely used for direct examination of polymeric materials (analysis of additives, catalyst residues, etc.) from research to recycling, through production and quality control, to troubleshooting. Many problems meet the concentration range in which conventional XRF is strong, namely from ppm upwards. Table 8.42 is merely indicative of the presence of certain additive classes corresponding to elemental analysis element combinations are obviously more specific for a given additive. It should be considered that some 60 atomic elements may be found in polymeric formulations. The XRF technique does not provide any structural information about the analytes detected the technique also has limited utility when... 

In view of the different manifestations of psychopathological behaviors found in diverse groups that cannot be adequately accounted for by factors concerning race, ethnic group or the acculturation process, Agbayani-Siewert et al. (1999) put forward a model that allows direct examination of the impact of cultural factors on psychopathological manifestations, while continuing to include structural social factors. 

There is little published information that directly examines ethnic differences in olanzapine pharmacokinetics or pharmacodynamics. Indirectly, examining stable... 

Studies directly examining the metabolism of organophosphate ester hydraulic fluids in animals are limited. One study identified metabolites in ether extracts of bile obtained from rabbits given single,... 

Q. Dr. Hoerlein, on direct examination you stated categorically that as to the meetmg of the 29th of December, 1941, you were not sent the minutes ... 

On direct examination by his defense counsel, Ter Meer had stated that in 1936 the German government issued an order prohibiting the giving of the know-how for processing and manufacture of buna rubber to anyone in the United States. 

Q. Now, bearing in mind that "the German authorities were very generous and fair about it," I would like to read you from the exhibit you referred to in your direct examination, and then I will ask you a question I think you can answer simply.. . . ... 

After the court adjourned about 4 30,1 asked Duke to come to ray office to talk about his cross-examination of Ambros, scheduled to take place in a few days (there would be an intervening weekend following Ambros direct examination). Sprech came in while Duke and I were getting warmed up. We discussed several lines of questioning. 

Q. On your direct examination, you testified about your relationship with the SS Obergruppenfuehrer Pohl. Dr. Hoffman asked you if in any way you suggested to Pohl the use of inmates. You answered "no." Now Dr. Ambros, do you recall any occasion on which you complained to Pohl about your difficulties in getting labor ... 

Q. Dr. Krauch, I have only a very few questions. You said some time ago in your direct examination, if I remember correctly, that before 1933 a German statesman once said that "without Farben no foreign policy was possible." May I ask you to interpret this statement ... 

To date, there have only been a limited number of studies directly examining PKC in bipolar disorders [77], Although undoubtedly an oversimplification, particulate (membrane) PKC is sometimes viewed as the more active form of PKC, and thus an examination of the subcellular partitioning of this enzyme can be used as an index of the degree of activation. Friedman etal. [78] investigated PKC activity and PKC translocation in response to serotonin in platelets obtained from bipolar-disorder patients before and during lithium treatment. They reported that the ratios of platelet-membrane-bound to cytosolic PKC activities were elevated in the manic patients. In addition, serotonin-elicited platelet PKC translocation was found to be enhanced in those patients. With respect to brain tissue, Wang and Friedman [74] measured PKC isozyme levels, activity and translocation in postmortem brain tissue from patients with bipolar disorder, and reported increased PKC activity and translocation in the brains of bipolar patients compared with controls, effects which were accompanied by elevated levels of selected PKC isozymes in cortices of bipolar disorder patients. 

Recovery of C. immitis from infected tissues or secretions for direct examination and culture provides an accurate and rapid method of diagnosis. 

Electron probe microanalysis functions by direct examination of the primary X-rays produced when the specimen is used as a target for an electron beam. Focused electron beams allow a spot analysis of a 1 pm3 section of the specimen. One current development employs the electron beam within a scanning electron microscope to provide both a visual picture of the surface of the sample and an elemental analysis of the section being viewed. Spectra obtained from primary X-rays always have the characteristic emission peaks superimposed on a continuum of background radiation (Figure 8.32). This feature limits the precision, sensitivity and resolution of electron probe microanalysis. 

Results of studies on the role of serotonin-in the action of LSD, which were conducted on human subjects, may be more easily interpreted because they directly examined the hallucinogenic effects of LSD. Prior depletion of brain serotonin with reserpine accentuated the effects of LSD (34,71). As described above, prior treatment with a MAOI attenuated the effects of LSD (38,70) and... 

The presence or absence of pancreatic enzymes can only be satisfactorily decided by intraduodenal intubation and direct examination of samples of small intestinal contents after the administration of a suitable stimulus to pancreatic secretion (Fll). It is not sufficient to look at one enzyme only, such as trypsin, since a specific deficiency of lipase can occur (Sll). Assessment of the degree of hydrolysis of fat in the stools is quite unreliable as a guide to pancreatic enzyme activity (CIO). 

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