Dispersoid Formation and Recrystallization Behavior in an Al-Mg-Si-Mn Alloy

The nucleation and precipitation of Mn-containing dispersoids in an Al-Mg-Si-Mn alloy (6082) have been studied by optical microscopy,EPMA (electron probe microanalysis) and TEM (transmission electron microscopy).The influence of Mn-containing dispersoids on the recrystallization behavior was also investigated.The size and distribution of dispersoids were strongly affected by both the homogenization process and the alloying element distribution formed in the direct chill cast procedure.The Mn-containing dispersoids were observed to nucleate preferentially on the β-Mg 2 Si phase and to be aligned along the 100 direction of the matrix.After cold deformation,the morphology of dispersoids greatly influences the recrystallization and grain growth behavior in the annealing process.     

The pterygoideus propius muscle revisited

We present our experience with 980 women who had subcutaneous forehead lifts using the anterior hairline incision, during the years 1989-1996. The dissection is easy and fast; the forehead wrinkles are smoothed by the separation of the septa between the frontalis and the skin. The access to the corrugator and the procerus muscles is easy, and the adjustment of the brows to the desired location can be accurate. We use this approach for 90% of women who are eligible for upper face rejuvenation. We have obtained a 96% satisfaction rate; only 1.8% of our patients had minor and reversible complications. The scar, which is supposed to be the main disadvantage of this procedure, is almost unnoticeable, and none of our patients has permanently changed her hairstyle due to this operation. Now, during the peak of interest in forehead lifts with limited scars using the endoscope, is the time to highlight this time-worn, safe, reproducible, and effective approach.     

Growth of GaN/AlxGa1-xN (x=0.65) Superlattices on Si(111) Substrates Using RF-MBE

Superlattices with varying GaN well widths (2, 3, 6, 9 nm) and fixed AlGaN barrier (8 nm) with high Al-content (x=0.65) were grown. Streaky RHEED patterns indicated 2D growth mode for the superlattices. XRD measurements showed multiple satellite peaks corresponding to uniform periodicity of the GaN/AlGaN pairs. The AlGaN barrier XRD peak also shifted with increasing well widths, while the GaN XRD peak was nominally unchanged. Room temperature photoluminescence experiments revealed peak emissions at energies lower than the bulk GaN energy gap. The large red shift with respect to the bulk gap is attributed to significant Stark effect for wide multiple quantum wells.     

BONE PARTICLE CONTENT OF SOME MINCED FISH MUSCLE PRODUCTS

Minced fish muscle recovered by flesh separators may vary in bone particle content depending on the type of machine and the size of the openings that the fish are passed through to screen out the skin and bones. Orderly marketing of these materials will require some measure of control of the bone particle content. The method presented here for quantifying the bone particle content of minced flesh by gravity-flotation involves (1) shredding the flesh with a low-speed stirring device and (2) gravity separation of the bone, cartilage and other high-density components from the lower-density floatable muscle fibers. Experimental samples obtained by passing various fish materials through flesh separators and then through 1- and 2-mm flesh strainers were analyzed for their bone particle content by the proposed method. The bone particle content of flesh containing 25 to more than 100 particles per pound could be reduced by 70–100% by passage through strainers. Imported commercial samples displayed bone particle contents of 4 to over 400 per pound. Sensory panels could not detect more than 10% of the particles found by objective analysis. The gravity-flotation method may serve as a useful quality control tool.     

Effects of docosahexaenoic acid or arachidonic acid supplementation on gene expression and contractile force of rat cardiomyocytes in primary culture

While fatty acids play essential roles in the physiology of the myocardium, conventional culture media contain little lipid. We previously revealed that rat neonatal myocardium mainly contains docosahexaenoic (DHA), linoleic (LA), and arachidonic (AA) acids as polyunsaturated fatty acids (PUFAs), and these contents in cultured cardiomyocytes derived from fetal rats were markedly lower than those in the neonatal myocardium. In this study, we first assessed the effects of supplementation of DHA, LA, or AA on the fatty acid contents and the percentage change of contractile area in primarily cultured rat cardiomyocytes. Based on this assessment, we then evaluated the effects of DHA or AA supplementation on mRNA expression and further directly measured the contractile force of cardiomyocytes with the supplementations. This study revealed that percentage change of contractile area was maximized under 20 μM DHA or 50 μM AA supplementation while LA supplementation did not affect this contraction index, and that a widespread upregulation tendency of the mRNA expression related to differentiation, maturity, fatty acid metabolism, and cell adhesion was seen in the cultured cardiomyocytes with supplementation of DHA or AA. In particular, upregulation of the gene expression of cellular adhesion molecules connexin43 and N-cadherin were remarkable, whereas the effects on differentiation and maturation were less pronounced. Correspondingly, the increase of the percentage change of the contractile area of cardiomyocyte clusters in culture dishes with the supplementations was significant, whereas the enhancement of the contractile force was modest. These results suggest that supplementation of DHA or AA to the fetal cardiomyocyte culture may play effective roles in preventing the de-differentiation of the cardiomyocytes in culture and that the enhancement of the contractile performance may be mainly attributed to the improvement of intercellular connection.     

无线互联网的发展趋势和存在问题

随着知识经济时代的到来，在移动中接入互联网，获取急需信息已成为现代社会需求的必然。本文介绍了无线互联网的技术热点和国内外发展情况，分析了其在我国的发展趋势，同时也指出目前值得业界重视的一些问题。     

Electromechanical bending response of PZT/CNT-based polymer laminates subjected to concentrated load

This paper presents the electromechanical behavior of piezoelectric/carbon nanotube (CNT)-based polymer laminates under three-point bending. The laminate was fabricated using thin lead zirconate titanate (PZT) and multi-walled carbon nanotube (MWNT)-based polycarbonate layers. The three-point bending tests were conducted on the PZT/MWNT-based polycarbonate laminates, and the dependence of the displacement and output voltage due to mechanical loads on the nanotube content and the material dimensions were measured and discussed. The output power was then calculated. This study showed that the piezoelectric/CNT-based polymer laminates can generate power without external load resistance.     

Electrical resistance-based strain sensing in carbon nanotube/polymer composites under tension: Analytical modeling and experiments

This paper presents an analytical and experimental study on the strain sensing behavior of carbon nanotube (CNT)-based polymer composites. Tensile tests were conducted on CNT/polycarbonate composites and the responses in the electrical resistance were measured during the tests. An analytical model incorporating the electrical tunneling effect due to the matrix material between CNTs was also developed to describe the electrical resistance change as a result of mechanical deformation. The model deals with the inter-nanotube matrix deformation at the micro/nanoscale due to the macroscale deformation of the nanocomposites. A comparison of the analytical predictions and the experimental data showed that the proposed model captures the sensing behavior. In addition, the effect of the micro/nanoscale structures on the strain induced resistance change was discussed to provide useful information for designing CNT-based polymer composites with high strain sensing capability.     

High Current Injection into Dynamic p–n Homojunction in Polymer Light‐Emitting Electrochemical Cells

Ions and electrons in blends of polymer–electrolyte can work in ensemble to operate light‐emitting electrochemical cells (LECs), in which the unique features of in situ formed p–n homojunctions offer efficient charge injection and transport. However, electrochemical features give rise to significant stability and speed issues due to limited electrochemical stability and low ion mobility, resulting in low brightness and a slow response of LECs. Here, these issues are overcome by the separate control of ionic and electronic charges, using a simple driving pulse superimposed on a small base voltage; ions with slow response are rearranged by a constant base voltage, while a high‐voltage pulse, superimposed upon the base, injects electrons/holes which have fast response, with minimal effect on the ions. This scheme successfully injects an extremely high current density of > 2 kA cm^?2 with a balanced electron/hole ratio, at a high‐speed response time of ≈ 50 ns; both properties demonstrate advantages of LECs in making polymers brighter. An in situ electron spin resonance measurement on the LECs further revealed that this impressive performance is due to the highly doped polymers, whose spin density reached 7 × 10¹⁹ spins cm^?3, and an ordered polymer structure in the active layer blend.