High-strength and high-modulus poly(vinyl alcohol) by the gel-ageing methodPart II The effect of the gel pressing temperature

It was reported in our previous paper that a relatively high-strength and high-modulus drawn poly(vinyl alcohol) (PVA) film could be obtained from aged gel sheet. In this paper, the effect of pressing temperature, at which the original PVA/dimethylsulphoxide/water gel was pressed into the gel sheet, on the tensile properties (modulus and strength) of the finally obtained drawn film is reported. The properties of the drawn films are discussed in relation to the structure of the undrawn films and the gel sheet, by birefringence and molecular orientation measurements, differential scanning calorimetry, and X-ray diffraction methods. As a result, the content of the low melting-temperature crystal component in the pressed gel is shown to be the most effective factor affecting the properties of the drawn film. © 1998 Chapman & Hall     

An optical chemical sensor using a fluorophor- embedded Langmuir-Blodgett film

An optical sensor with a Langmuir-Blodgett (LB) film was developed for simultaneous recognition of amino acids in an aqueous solution. Anthroyloxy- stearate-containing stearate LB films and perylene-containing arachidate LB films were deposited on a quartz glass. The fluorescence of these LB films in an aqueous solution was quenched in response to amino acids. Amino acids were classified into five groups by the pattern of fluorescence quenching of anthroyloxy stearate and perylene LB films.     

Role of glial filaments in cells and tumors of glial origin: a review

In the adult human brain, normal astrocytes constitute nearly 40% of the total central nervous system (CNS) cell population and may assume a star-shaped configuration resembling epithelial cells insofar as the astrocytes remain intimately associated, through their cytoplasmic extensions, with the basement membrane of the capillary endothelial cells and the basal lamina of the glial limitans externa. Although their exact function remains unknown, in the past, astrocytes were thought to subserve an important supportive role for neurons, providing a favorable ionic environment, modulating extracellular levels of neurotransmitters, and serving as spacers that organize neurons. In immunohistochemical preparations, normal, reactive, and neoplastic astrocytes may be positively identified and distinguished from other CNS cell types by the expression of the astrocyte-specific intermediate filament glial fibrillary acidic protein (GFAP). Glial fibrillary acidic protein is a 50-kD intracytoplasmic filamentous protein that constitutes a portion of, and is specific for, the cytoskeleton of the astrocyte. This protein has proved to be the most specific marker for cells of astrocytic origin under normal and pathological conditions. Interestingly, with increasing astrocytic malignancy, there is progressive loss of GFAP production. As the human gene for GFAP has now been cloned and sequenced, this review begins with a summary of the molecular biology of GFAP including the proven utility of the GFAP promoter in targeting genes of interest to the CNS in transgenic animals. Based on the data provided the authors argue cogently for an expanded role of GFAP in complex cellular events such as cytoskeletal reorganization, maintenance of myelination, cell adhesion, and signaling pathways. As such, GFAP may not represent a mere mechanical integrator of cellular space, as has been previously thought. Rather, GFAP may provide docking sites for important kinases that recognize key cellular substrates that enable GFAP to form a dynamic continuum with microfilaments, integrin receptors, and the extracellular matrix.     

Obesity and insulin resistance syndrome

Obesity is commonly associated with insulin resistance. The etiology of insulin resistance syndrome such as syndrome X or deadly quartet is not clear. We have proposed visceral fat syndrome, in which fat accumulation is predominant in the intra-abdominal cavity, frequently accompanied by disorders of glucose and lipid metabolism, and also hypertension. Excess free fatty acid of the portal circulation may cause the enhancement of lipid synthesis and gluconeogenesis as well as insulin resistance, resulting in hyperlipidemia, glucose intolerance and hypertension and finally atherosclerosis. Enhanced production of PAI-1 by increased visceral fat may be partly responsible for the development of cardiovascular disease in patient with visceral fat assmulation.     

Wear properties of perpendicular magnetic recording media

Wear properties of sputtered Co-Cr/permalloy double layer on flexible substrate with and without an inorganic protective top layer were studied under simulated tribological conditions. A soft head slider (ex. glass) gave even severer damage to media than the hard one (ex. Al2O3-TiC), and a 200 Å thin inorganic protective top layer was effective enough to enhance resistance against wear. Read-write experiments were also done with use of the double layer flexible media with the protective top layer (200 Å in thickness) by running them on a specially designed driver unit with an Al2O3.TiC spherical SPT head. An out-put signal loss was no more than 3dB even after 10 million times of the head passes.     

A study of real-time and 100 billion agents simulation using the Boids model

In high-performance computing of multi-agent systems, there often exists a load imbalance that slows down the calculation. In this paper, we discuss the parallelization of the Boids model for simulating a swarm intelligence. We apply the multi-level hierarchy of parallelism to the Boids model to mitigate the load-imbalance problem. To eliminate numerical errors due to parallelization, we apply pseudo-quadruple arithmetic. The parallel performance is evaluated on three major architectures, including many-core processors on an x86-based server with GPUs, and the Earth Simulator. The parallelization can decrease the negative effects of a load imbalance to almost zero in a simulation of 50 million agents. In addition, the parallelization guarantees the reproducibility of the results in a sequential execution. The strong scaling shows the potential to complete a simulation in real-time on the Earth Simulator. In addition, the weak scaling shows the ability to calculate 100 billion agents within a reasonable amount of time.     

Effect of crystal orientation on galvanoluminescence of aluminium

When high purity aluminium sheets containing large single crystals were anodized galvanostatically in barrier-forming organic acid solutions, such as tartaric, citric acids etc, the distinct difference in the intensity of galvanoluminescence appeared to correspond exactly with the variation of the rate of oxide growth on underlying crystal planes.The intensity of the luminescence was stronger with a crystal plane where the rate of the film growth was higher. Therefrom, the effect of underlying metal orientation on the luminescence was interpreted as a secondary phenomenon due to the difference in the thickness of the film growing on the different crystal planes.