Effect of Porosity and Grain Size on the Microwave Dielectric Properties of Sintered Alumina

The real part of the permittivity (epsilon') and the tan of sintered alumina (Al₂O₃) at about 9 GHz have been measured. The dielectric properties have been examined as a function of purity, pore volume, and sintered grain size. The tan is found to depend very strongly on the pore volume, purity, and grain size. ɛ' is far less sensitive to impurities and grain size. The dependence of ɛ' on porosity can be described by simple mixture models as expected. A model of losses in single crystals cannot be extended easily to these materials where extrinsic factors such as porosity, random crystal orientation, grain boundaries, microcracks, and impurities dominate. These factors have been studied in an attempt to describe the tan δ and ɛ' of sintered polycrystalline alumina. In this work, the tan δ for alumina has been studied in near-theoretical density ranges between 9.1 × 10₋₅ and 2.4 × 10₋₅ depending on grain size.     

Pathognomic versus developmentally appropriate self-focus during adolescence: Theoretical concerns and clinical implications.

Presents distinctions between the adaptive and developmentally appropriate aspects of adolescent self-focus and the maladaptive pattern of self-focus manifested by clinical samples. It is argued that self-focus, whether adaptive or pathological, varies along 6 dimensions: (1) content, (2) valence, (3) intensity, (4) duration, (5) consistency, and (6) purpose. The authors describe each dimension and provide a case illustration of a 20-yr-old Caucasian male with depressive symptoms and suicidal ideation. It is concluded that attention to the 6 dimensions of self-focus may serve as a heuristic for guiding the clinical interview and for monitoring and catalyzing improvement in an adolescent's view of the self. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

SYTLYN - a program for sight line calculation

The problem described in this article is essentially one of visibility in a steelworks. During work on a development project at Ebbw Vale, a problem was encountered in the siting of work stations in order to give the operatives a good view of the machine they controlled. After reviewing possible manual methods and their advantages and disadvantages, the authors describe the program and its objectives. A computer program was developed to draw, on an incremental plotter, a view of the line from any point. The drawings produced were in a form that gave a 360 degrees view. After discussion of the specification of the shape of objects, and the interpretation of SYTLYN plots, the program's advantages and limitations are discussed, together with some other applications in glare studies, lighting, etc, and likely future developments.     

Analysis of Volatile Organic Compounds in Human Saliva by a Static Sorptive Extraction Method and Gas Chromatography-Mass Spectrometry

Human saliva not only helps control oral health (with anti-microbial proteins), but it may also play a role in chemical communication. As is the case with other mammalian species, human saliva contains peptides, proteins, and numerous volatile organic compounds (VOCs). A high-throughput analytical method is described for profiling a large number of saliva samples to screen the profiles of VOCs. Saliva samples were collected in a non-stimulated fashion. The method utilized static stir bar extraction followed by gas chromatography-mass spectrometry (GC-MS). The method provided excellent reproducibility for a wide range of salivary compounds, including alcohols, aldehydes, ketones, carboxylic acids, esters, amines, amides, lactones, and hydrocarbons. Furthermore, substantial overlap of salivary VOCs and the previously reported skin VOCs in the same subject group was found in this study by using pattern recognition analyses. Sensitivity, precision, and reproducibility of the method suggest that this technique has potential in physiological, metabolomic, pharmacokinetic, forensic, and toxicological studies of small organic compounds where a large number of human saliva samples are involved.     

Panel VI: Ethnic minorities, health care systems, and behavior.

This article presents an overview of research on health care use and provider behavior, on doctor–patient relationships, adherence to medical regimens, self-care, practices and avoidance health care behaviors, and attitudes of 4 ethnoracial groups: African Americans, American Indians, Asian Americans, and Latinos. Although issues within the groups varied, common themes between the groups emerged. It became apparent, after discussion, that whatever the issues and health problems, these can be resolved most effectively when addressed within the social contexts of each ethnoracial group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enzymatic tissue digestion as an alternative sample preparation approach for quantitative analysis using liquid chromatography-tandem mass spectrometry

Compound extraction from biological tissue often presents a challenge for the bioanalytical chemist. Labor-intensive homogenization or sonication of whole or powdered tissue is performed before compounds can be extracted and analyzed. Enzymatic digestion is commonly used for tissue dissociation and cell harvesting and offers the advantages of unattended sample preparation, potential automation, and low cost. The feasibility of enzymatic digestion as an alternate tissue preparation technique was evaluated for bioanalysis of drugs in conjunction with LC/MS/MS. Two different enzymes (collagenase and proteinase K) that are known to degrade connective tissues to allow tissue dissolution were chosen for evaluation, employing well-known antidepressants desipramine and fluoxetine as test compounds in dog and rat brain tissue. Comparison between enzymatic digestion and conventional homogenization tissue preparation was performed, including investigation of matrix ionization suppression of both methods using a postcolumn infusion system. Results showed that enzymatic digestion has extraction efficiency comparable to homogenization. Matrix ionization suppression was not observed for either the test compounds evaluated or the sample extraction method. Test compound levels of incurred tissue samples prepared by enzymatic digestion were in good agreement with the values obtained by the conventional homogenization tissue preparation, indicating that enzymatic digestion is an appropriate tissue sample preparation method.     

Individual and gender fingerprints in human body odour

Individuals are thought to have their own distinctive scent, analogous to a signature or fingerprint. To test this idea, we collected axillary sweat, urine and saliva from 197 adults from a village in the Austrian Alps, taking five sweat samples per subject over 10 weeks using a novel skin sampling device. We analysed samples using stir bar sorptive extraction in connection with thermal desorption gas chromatograph-mass spectrometry (GC-MS), and then we statistically analysed the chromatographic profiles using pattern recognition techniques. We found more volatile compounds in axillary sweat than in urine or saliva, and among these we found 373 peaks that were consistent over time (detected in four out of five samples per individual). Among these candidate compounds, we found individually distinct and reproducible GC-MS fingerprints, a reproducible difference between the sexes, and we identified the chemical structures of 44 individual and 12 gender-specific volatile compounds. These individual compounds provide candidates for major histocompatibility complex and other genetically determined odours. This is the first study on human axillary odour to sample a large number of subjects, and our findings are relevant to understanding the chemical nature of human odour, and efforts to design electronic sensors (e-nose) for biometric fingerprinting and disease diagnoses.     

Ground terminations of lightning protective systems

In a lightning protective system, the ground terminations must be designed to keep within fixed values the step voltage both inside and outside the protected structure and the maximum total voltage. Design criteria shall take into account that the behavior of ground systems is affected by their length, by soil resistivity, by amplitude and wave shapes of lightning currents. In this paper, investigations carried out on ground terminations when subjected to impulse currents are presented and typical phenomena which characterize their behavior are summarized. Theoretical analysis of the transient phenomenon and new experimental results on each electrode are presented. On the basis of maximum step voltage and of the statistical variation of lightning currents, the design of ground terminations is analyzed and curves for their practical sizing are given. Provisions to avoid discharges into the soil between ground conductors and buried cables or pipes are given, together with computation methods to evaluate overvoltage amplitudes between live conductors and ground in shielded cables