Molecular correlations in sheared thermotropic copolyesters showing banded textures

Banded textures produced in a thermotropic liquid crystal polymer by shearing between glass slides are examined by using both transmission electron and polarized light microscopy. The periodic variation in director orientation about the shear axis, as measured by light microscopy, is shown to be distinctly different from that indicated by electron diffraction. Measurements of birefringence and observation of Zernicke phase contrast indicate periodic variations in optical properties of the polymer, in step with the bands. Such effects are accounted for in terms of a synchronous rotation of the planar aromatic groups about the molecular chain axes. Evidence for an out-of-plane component of molecular orientation is also presented.     

Effect of degumming on the tensile properties of silkworm (Bombyx mori) silk fiber

Forcibly reeled silkworm (Bombyx mori) silk was used to study how exposure to a degumming treatment (boiling in distilled water for 30 min) affects tensile properties. Because forcibly reeled and naturally spun fibers exhibit comparable mechanical behavior, the results can be generalized to material obtained conventionally from cocoons. The effects of degumming include: a decrease in the initial elastic modulus, a decrease in the stress at the proportional limit (yield strength), a change in the qualitative shape of force‐displacement curves, and significant qualitative and quantitative variability in force‐displacement data from samples subjected to nominally identical degumming histories. Immersion in water at room temperature or heating in air at 100°C for 30 min are both qualitatively equivalent to a 30‐min degumming treatment in boiling water, in terms of the effect on silk tensile properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1431–1437, 2002; DOI 10.1002/app.10366     

Characterizing the cross-sectional geometry of thin,non-cylindrical,twisted fibres (spider silk)

Quantitative tensile property evaluation of fibres requires accurate cross-sectional area measurement at a location close to the point of failure. Laser diffraction was evaluated as a non-destructive technique for characterizing the cross-sectional geometry of translucent, non-cylindrical, and/or twisted fibres with thicknesses in the range 2–5 m. Forcibly silked major ampullate fibres from Nephila clavipes spiders were used as specimens. Scanning electron microscopy was used to calibrate the extent to which laser diffraction over- or under-estimates fibre diameter. For the purpose of area measurement, elliptical or oval cross-sections can be treated as though they were circular. We demonstrate mathematically that the area can be obtained to within a few per cent of the true value, if (a) the circle is assigned an equivalent diameter equal to the average of at least four measurements of apparent diameter, (b) the apparent diameter measurements are taken at equal intervals of fibre rotation through a 180° range, and (c) the axial ratio of the cross-section is less than 1.5. The extent to which a non-cylindrical fibre is twisted can be deduced from the periodicity of bright and dark regions that alternate along the length of the fibre in reflected light. Values of cross-sectional ellipticity and area measured from a twisted fibre were smaller than the corresponding values obtained from a twist-free fibre. The apparent diameter of twist-free major ampullate fibre was found to be highly variable-by as much as ±20% relative to the mean within a 0.6 mm length. Therefore, local measurements of area, rather than a value derived from fibre denier, should be used in tensile property evaluation of this material.     

The radical empiricism of William James and philosophy of history.

William James's philosophy of history is explored in his classic psychological and philosophical works and in 2 articles he devoted specifically to the topic. Historical issues are set forth in terms of James's individualism, pragmatism, and radical empiricism. It is argued that a Jamesian philosophy of history provides a reasoned and believable middle way between the extremes of realism and constructionism. James believed that historical change is brought about both by the contributions of individuals and by forces in cultures and the environment that help shape the direction of things. Finally, the author explores implications of James's pluralism for history and his quarrel with absolutistic conceptual schemes that attempt to reduce all things to 1 thing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-aspect ratio and horizontally oriented carbon nanotubes synthesized by RF-cCVD

Horizontally aligned long carbon nanotubes were efficiently synthesized on Si substrates by using a radio-frequency catalytic chemical vapor deposition method. The morphological as well as the growth properties of these nanotubes were systematically investigated with various analytical techniques including microscopy and Raman spectroscopy. Different reaction parameters such as temperature, type of hydrocarbon gas and catalyst amount were varied and their effects on the nanotube size, quality and alignment are reported. High-aspect ratio and horizontally oriented nanotubes were found to grow following the “tip growth” mechanism. The fast and localized heating rate produced by the RF generator helps nanotubes to separate and lift the nano-particles away from the support and hence contributes to the growth of CNTs with a very high-aspect ratio. Carbon nanotubes synthesized with methane show a better horizontal alignment compared to those synthesized with acetylene, which might be due to the flow rate of the hydrocarbon gas.     

Design and application considerations for motors in steep-frontedsurge environments

A large body of research has been conducted in the past 15 years into steep-fronted surges in electrical systems and their propagation in AC machine windings. This paper reviews the nature of the surge, the factors that determine its amplitude and rise time, and how it affects the motor winding. It then explains how its harmful effects can be controlled by system and winding design and by effective quality control. Related national and international standards are discussed and their shortcomings pointed out. Uncertainties in the prediction of amplitude and rise time of surges are explained, and guidance for cost effective specification of motors for application in a surge environment is given     

The Effects of Personal Construct Group Therapy on Breast Cancer Survivors.

In this study, the authors evaluated the effects of a brief personal construct group therapy on breast cancer survivors (N = 42) randomly assigned to either the treatment or wait-list control condition. The Gottschalk Gleser Content Analysis Scales were used to measure the effects for group across time (preand posttreatment, pretreatment, and 3-month posttreatment) on the personal construct states of threat, threat to existence, dislocation, and hope. Analyses showed that the beneficial effects of therapy achieved posttreatment were maintained at 3-month follow-up. The therapeutic group factors (I. D. Yalom, 1995) identified by the therapy group members as helpful in achieving these outcomes are also reported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personal construct therapy for HIV seropositive patients.

Reports the application of constructivist assumptions of personal construct therapy to homosexual HIV seropositive patients as part of a psychotherapy research program. The underlying constructivist theory is briefly described, followed by the assumptions shared by personal construct therapists with other cognitive therapists, as well as their differences. A constructivist model of psychological reactions to being HIV seropositive is discussed, together with 3 cases that illustrate it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inflammatory Process and Molecular Targets for Antiinflammatory Nutraceuticals

Intense interest in nutraceuticals and their potential benefits has created the need to review the existing scientific information on their effect in preventing and managing inflammation that accompanies most chronic diseases. This article reviews the basic mechanisms of inflammation and the potential of 9 nutraceuticals to be effective as chronic disease preventive agents. Furthermore, the article emphasizes studies in which nutraceuticals are shown to be effective in preventing inflammation and mentions other molecular targets that can be of use in the future. The effects of the following nutraceuticals: α‐tocopherol, ascorbic acid, curcumin, resveratrol, (‐)‐epigallocatechin gallate, theaflavin, genistein, omega‐3 fatty acids, and lycopene on reactive oxygen species scavenging ability, as well as proinflammatory targets, such as tumor necrosis factor α interleukin‐1, interleukin‐1β, nuclear factor kappa B, cellular and adhesion molecules, cyclooxygenase‐2, inducible nitric oxide synthase, 5‐lipoxygenase (5‐LOX), phospholipase A₂, reactive oxygen species generating enzymes are discussed.