The viscoelastic properties of narrow-distribution polystyrenes have been measured in the molten state by means of a concentric cylinder type rheometer over wide ranges of frequency and temperature. From the frequency dependence of the storage shear modulus G' and the loss modulus G", the characteristic parameters in the so-called terminal zone, such as zero-shear viscosity 0, elasticity coefficient Ac,, and steady-state compliance •8 have been evaluated, and the dependence of these parameters on the molecular weight M has been discussed. 0, Ac, and " for samples having molecular weight higher than the critical molecular weight Me are proportional to 1 23 4•7, M7•5 6, and M°, respectively. For samples having molecular weights lower than Me, 8 is proportional to M, as is predicted by the modified Rouse theory. The quasi-equilibrium modulus Gex8 evaluated from G' in the rubbery region shows a constant value of 2.0 X 10s, independent of M. This value agrees very well with that obtained by integration of the G" vs. log curve. The average molecular weight between entanglement coupling loci, Me, and the average chain length, Ze, have been calculated from Gex°to be 18,000 and 346, respectively. The current molecular theories for entanglement coupling have been discussed on the basis of these experimental results. The temperature and molecular weight dependences of the shift factor aT were also discussed, and a few parameters on the free volume, such as the Vogel temperature T0 and the temperature coefficient of the fractional free volume a¡ have been determined for narrow-distribution polystyrenes.

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Thermal emission in the infrared range is important in various fields of research, including chemistry, medicine and atmospheric science. Recently, the possibility of controlling thermal emission based on wavelength-scale optical structures has been intensively investigated with a view towards a new generation of thermal emission devices. However, all demonstrations so far have involved the 'static' control of thermal emission; high-speed modulation of thermal emission has proved difficult to achieve because the intensity of thermal emission from an object is usually determined by its temperature, and the frequency of temperature modulation is limited to 10-100 Hz even when the thermal mass of the object is small. Here, we experimentally demonstrate the dynamic control of thermal emission via the control of emissivity (absorptivity), at a speed four orders of magnitude faster than is possible using the conventional temperature-modulation method. Our approach is based on the dynamic control of intersubband absorption in n-type quantum wells, which is enhanced by an optical resonant mode in a photonic crystal slab. The extraction of electrical carriers from the quantum wells leads to an immediate change in emissivity from 0.74 to 0.24 at the resonant wavelength while maintaining much lower emissivity at all other wavelengths.

Abstract-High precision assembly of mechanical parts requires accuracy exceeding the robot precision. Conventional part mating methods used in the current manufacturing requires tedious tuning of numerous parameters before deployment. We show how the robot can successfully perform a tight clearance peg-in-hole task through training a recurrent neural network with reinforcement learning. In addition to saving the manual effort, the proposed technique also shows robustness against position and angle errors for the peg-in-hole task. The neural network learns to take the optimal action by observing the robot sensors to estimate the system state. The advantages of our proposed method is validated experimentally on a 7-axis articulated robot arm.

Earlier studies, including our own, revealed that activation of mast cells is accompanied by production of reactive oxygen species (ROS) that help to mediate the release of the inflammatory mediators, including histamine and eicosanoids. However, little is known about the mechanisms of ROS production, including the species of oxidants produced. In this study we show that in both the RBL-2H3 mast cell line and bone marrow-derived mast cells, FcεRI cross-linking stimulates intracellular oxidative burst, including hydrogen peroxide (H2O2) production, as defined with the oxidant-sensitive dyes dichlorofluorescein and scopoletin and the selective scavenger ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one). The oxidative burst was observed immediately after stimulation and was most likely due to an NAD(P)H oxidase. Experiments using selective pharmacological inhibitors demonstrated that activation of tyrosine kinases and phosphatidylinositol-3-kinase is required for induction of the oxidative burst. Blockade of the oxidative burst by diphenyleneiodonium impaired the release of preformed granular mediators, such as histamine and β-hexosaminidase, and the secretion of newly synthesized leukotriene C4, whereas selective scavenging H2O2 by ebselen impaired leukotriene C4 secretion, but not degranulation. Sustained elevation of cytosolic calcium through store-operated calcium entry was totally abolished when ROS production was blocked. In contrast, selective depletion of H2O2 caused a considerable decrease and delay of the calcium response. Finally, tyrosine phosphorylation of phospholipase Cγ and the linker for activation of T cells, an event required for calcium influx, was suppressed by diphenyleneiodonium and ebselen. These studies demonstrate that activation of the intracellular oxidative burst is an important regulatory mechanism of mast cell responses.

Acetabular retroversion occurs more commonly in association with a variety of hip diseases, in which the prevalence of subsequent degenerative arthritis is increased, than has been previously noted.

Six flavonoid glycosides, eriocitrin (1), narirutin (2), hesperidin (3), luteolin-7-O-rutinoside (4), isorhoifolin (5), diosmin (6), rosmarinic acid (7) and 5,7-dihydroxycromone-7-O-rutinoside (8), were isolated from the aerial part of Mentha piperita L. Among these compounds, compound 4 showed a potent inhibitory effect on histamine release induced by compound 48/80 and antigen-antibody reaction. This compound was more effective than luteolin and luteolin-7-O-glucoside in inhibiting histamine release from rat peritoneal mast cells. Compound 4 also caused a dose-related inhibition of the antigen-induced nasal response and significant effects were observed at doses of 100 and 300 mg/kg. These results indicate that compound 4 may be clinically useful in alleviating the nasal symptoms of allergic rhinitis.Key words Mentha piperita L.; flavonoid glycoside; antiallergic effect; rat peritoneal mast cell; histamine 256 Notes Biol.

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