Elevated temperature strain gages

One of the goals of the HOST Program is the development of electrical resistance strain gages for static strain measurements at temperatures equal to or greater than 1273 K. Strain gage materials must have a reproducible or predictable response to temperature, time and strain. It is the objective of this research to investigate criteria for the selection of materials for such applications through electrical properties studies. The results of the investigation of two groups of materials, refractory compounds and binary alloy solid solutions are presented

Structural Properties, Order-Disorder Phenomena and Phase Stability of Orotic Acid Crystal Forms

Orotic acid (OTA) is reported to exist in the anhydrous (AH), monohydrate (Hy1) and dimethylsulfoxide monosolvate (SDMSO) forms. In this study we investigate the (de)hydration/desolvation behavior, aiming at an understanding of the elusive structural features of anhydrous OTA by a combination of experimental and computational techniques, namely, thermal analytical methods, gravimetric moisture (de)sorption studies, water activity measurements, X-ray powder diffraction, spectroscopy (vibrational, solid-state NMR), crystal energy landscape and chemical shift calculations. The Hy1 is a highly stable hydrate, which dissociates above 135°C and loses only a small part of the water when stored over desiccants (25°C) for more than one year. In Hy1, orotic acid and water molecules are linked by strong hydrogen bonds in nearly perfectly planar arranged stacked layers. The layers are spaced by 3.1 Å and not linked via hydrogen-bonds. Upon dehydration the X-ray powder diffraction and solid-state NMR peaks become broader indicating some disorder in the anhydrous form. The Hy1 stacking reflection (122) is maintained, suggesting that the OTA molecules are still arranged in stacked layers in the dehydration product. Desolvation of SDMSO, a non-layer structure, results in the same AH phase as observed upon dehydrating Hy1. Depending on the desolvation conditions different levels of order-disorder of layers present in anhydrous OTA are observed, which is also suggested by the computed low energy crystal structures. These structures provide models for stacking faults as intergrowth of different layers is possible. The variability in anhydrate crystals is of practical concern as it affects the moisture dependent stability of AH with respect to hydration

Elevated temperature strain gages

The objective is to study the electrical resistance of materials that are potentially useful as resistance strain gages at 1000 C. A set of criteria were set and used to select strain gage candidate materials that are electrically stable and reproducible at all temperatures up to 1000 C. For the experimental phase of this research, the electrical resistance change with temperature of three groups of materials (solid solution alloys, transition metal carbides, and semiconductors) were studied with the intention of identifying materials with low temperature coefficient of resistance and low resistance drift rate at 1000 C. A preliminary study of the gage factor on one of the best candidate materials, B sub 4 C, was also undertaken. The results of these investigations are presented

Desenvolvimento de currículo nas escolas de biblioteconomia para enfrentar o desafio da tecnologia da informação

Os avanços na tecnologia da informação possibilitam a especialistas de informação envolverem-se nos aspectos de processamento e uso da informação para a resolução de problemas e tomadas de decisão, o que não era possível anteriormente. Isto apresenta um desafio para as escolas de biblioteconomia desenvolverem novos cursos relacionados com a tecnologia da informação. Uma nova geração de estudantes esta surgindo, à procura de instrução voltada para as diversas carreiras nas atividades de informação. Os cursos existentes e os planejados em ciência de computadores, psicologia e inteligência artificial, ciência da administração e engenharia elétríca refletem os progressos na tecnologia da informação mas não preenchem o campo de maneira completa. Existe uma lacuna evidente a ser preenchida pelas escolas de biblioteconomia, do mesmo rnodo corno a nova geração de sistemas de informação computadorizados exige um ambiente rico em informação. Este artigo propõe um novo currículo universitário em ciência da informação, abrangendo aspectos de processamento e uso da informação não incluídos em cursos de outras disciplinas. Descritores Tecnologia da informação. Automação.Ciência da lnformação. Ensino de Biblioteconomia/Ciência da lnformação. Abstract Developments in information technology make it possible for information specialists to be involved in aspects of information processing and the use of information in problem solving and decision making that previously have not been possible. This presents a challenge to the library schools to develop new IT related courses. A new generation of students is appearing who seek education leading to careers in a wide spectrum of information activities. Existing and planned educational courses in computer science, psychology and artificial intelligence, management science, and electrica! engineering that reflect developments in IT do not cover the field entirely. There is a very obvious gap for the library schools to fill, as the new generation of computer-based information systems require and information rich environment. This paper proposes a new undergraduate programme in information science, covering aspects of information processing and use that are not included in courses in other disciplines

CO Line Emission and Absorption from the HL Tau Disk: Where is all the dust?

We present high-resolution infrared spectra of HL Tau, a heavily embedded young star. The spectra exhibit broad emission lines of hot CO gas as well as narrow absorption lines of cold CO gas. The column density for this cooler material (7.5+/-0.2 x 10^18 cm-2) indicates a large column of absorbing gas along the line of sight. In dense interstellar clouds, this column density of CO gas is associated with Av~52 magnitudes. However, the extinction toward this source (Av~23) suggests that there is less dust along the line of sight than inferred from the CO absorption data. We discuss three possibilities for the apparent paucity of dust along the line of sight through the flared disk: 1) the dust extinction has been underestimated due to differences in circumstellar grain properties, such as grain agglomeration; 2) the effect of scattering has been underestimated and the actual extinction is much higher; or (3) the line of sight through the disk is probing a gas-rich, dust-depleted region, possibly due to the stratification of gas and dust in a pre-planetary disk.Comment: To be published in The Astrophysical Journa

Maternal participant experience in a South African birth cohort study enrolling healthy pregnant women and their infants

Abstract Background Critical to conducting high quality research is the ability to attract and retain participants, especially for longitudinal studies. Understanding participant experiences and motivators or barriers to participating in clinical research is crucial. There are limited data on healthy participant experiences in longitudinal research, particularly in low- and middle-income countries. This study aims to investigate quantitatively participant experiences in a South African birth cohort study. Methods Maternal participant experience was evaluated by a self-administered survey in the Drakenstein Child Health Study, a longitudinal birth cohort study investigating the early life determinants of child health. Pregnant mothers, enrolled during the second trimester, were followed through childbirth and the early childhood years. Satisfaction scores were derived from the participant experience survey and quantitatively analyzed; associations between satisfaction scores and sociodemographic variables were then investigated using a linear regression model. Results Data were included from 585 pregnant mothers (median age 26.6 years), who had participated in the study for a median time of 16 months. Overall participant satisfaction was high (median score 51/60) and associated with increased attendance of study visits. Reasons for participating were a belief that involvement would improve their health, their child’s health or the health of family and friends. Potential reasons for leaving the study were inconvenience, not receiving clinical or study results, and unexpected changes in study visits or procedures. Variables associated with higher overall satisfaction scores were no prior participation in research, higher socioeconomic status, less intensive follow-up schedules and having experienced stressful life events in the past year. Conclusions Satisfaction scores were high and associated with increased visit attendance. Participants’ perceived benefits of study participation, most notably the potential for an improvement in the health of their child, were a significant motivator to enroll and remain in the study. The consistent theme of perceived health benefits as a motivator to join and remain in the study raises the question of whether participation in research results in actual improvements in health

^(13)C, ^1H, and ^2H NMR Observation of Trideuterated Cyclopropylmethyl-Cyclobutyl Carbocation: A Configurationally Stable Species

With the increasing power and sophistication of experimental and theoretical methods for assigning chemical structures, it seems almost incredible that the structure of any reasonably stable organic entity with a small number of carbons could remain enigmatic for very long. Nonetheless, this is true of C_4H_7^+-one of the first "nonclassical" cations to be discovered, which has some of the characteristics expected for a very rapidly equilibrating mixture of classical cyclopropylmethyl, cyclobutyl, and 3-butenyl cations and yet other characteristics which wholly belie any description that implies conventional charge distributions or geometries derived from structural representations using solid lines representing two-electron bonds