The rapid separation of aflatoxins on silica gel coated glass cylinders

A chromatographic method is described for the separation of aflatoxins on silica gel coated glass cylinders prepared with a chloroformacetone slurry. This can be done in 35–40 min compared with more than 2 hr for thin layer chromatography (TLC). This method is more rapid, economical and its sensitivity is comparable to TLC. University of Georgia College of Agriculture Experiment Stations, Journal Series Paper Number 643, College Station, Athens, Ga.     

Near room-temperature continuous-wave operation of all-monolithic InAlGaAs/InP 1.3 /spl mu/m VCSELs

InAlGaAs/InP-based all-monolithic 1.3 /spl mu/m VCSELs operating continuous wave up to 18/spl deg/C are demonstrated. The whole structure is grown by a single step of MOCVD. Selective wet etching of an InP layer is used to form an air-gap aperture for the current confinement. The threshold current of an 8 /spl mu/m device at 15/spl deg/C is /spl sim/2.8 mA.     

The viscosity approximation process for quasi-nonexpansive mappings in Hilbert spaces

In this paper, we discuss the strong convergence of the viscosity approximation method, in Hilbert spaces, relatively to the computation of fixed points of operators in the wide class of quasi-nonexpansive mappings. Our convergence results improve previously known ones obtained for the class of nonexpansive mappings.     

Tribological behavior of aluminum-CNT coated metal composite under dry and water lubricated conditions

Carbon nanotubes are considered the best material in the field of composites because of their mechanical and tribological properties. In this study, carbon nanotubes coated metal was dispersed in aluminum, the base metal, to improve the wettability between aluminum and carbon nanotubes. The friction and wear behaviors of the aluminum-carbon nanotube coated metal, which is a nickel and copper composite, were investigated using a pin-on-disk wear tester under dry sliding and water lubricated conditions and evaluated using SEM and EDX analysis. All the results demonstrated that the addition of the carbon nanotubes coated metal significantly improved the wettability of CNTs in the aluminum. And the distribution of CNTs prevented the propagation of micro cracks on the surface of the aluminum base metal sample, resulting in enhanced friction characteristics and wear resistance of the nano composite. The composite exhibited lower friction coefficient and wear resistance under the water lubricated condition than the dry sliding condition. Although the lubrication and cooling effect of water contributed to the reduction of the friction coefficient of the composite, the separation of wear particles from the sliding surface changed the wear type from three-body to two-body, resulting in very high wear rate. Also the concentration of oxide under water lubricated condition contributed to the increase of the wear rate because the amount of oxide film removed in terms of thickness exceeded the critical thickness of real contact area.     

Tribological Effects on the Wear Life of a Coating-Protected OPC Drum with Regard to Temperature,Load, and Rotation Speed

Greatly improved technology in laser printers requires that companies innovate to provide consumers with high-quality printed images, durable equipment, and low costs. The toner cartridge of a laser printer is where the organic photoconductor drum, also known as the OPC drum, is located, which is the central feature of the printer responsible for reproducing what has been created accurately on paper. However, with continuous printing, constant contact between the OPC drum and the paper, toner, and doctor blade causes wear and thus the quality of the image deteriorates and eventually will cause the equipment to fail, which then costs the consumer for repairs. In this study, we conducted a friction/wear test on the OPC drum to determine the relationships between temperature, load input, and rotational speed in the deterioration of an OPC drum, causing the end of its service life. Test results showed that load input with respect to increasing rotational speed increased the temperature in the OPC drum's surface during operation. With the increase in temperature, the average amount of wear on the surface of the drum increases. However, toner dispersion greatly influences the temperature increase in the OPC surface.     

Balanced Free Essential Amino Acids and Resistance Exercise Training Synergistically Improve Dexamethasone-Induced Impairments in Muscle Strength,Endurance, and Insulin Sensitivity in Mice

Our previous study shows that an essential amino acid (EAA)-enriched diet attenuates dexamethasone (DEX)-induced declines in muscle mass and strength, as well as insulin sensitivity, but does not affect endurance. In the present study, we hypothesized that the beneficial effects will be synergized by adding resistance exercise training (RET) to EAA, and diet-free EAA would improve endurance. To test hypotheses, mice were randomized into the following four groups: control, EAA, RET, and EAA+RET. All mice except the control were subjected to DEX treatment. We evaluated the cumulative rate of myofibrillar protein synthesis (MPS) using ²H₂O labeling and mass spectrometry. Neuromuscular junction (NMJ) stability, mitochondrial contents, and molecular signaling were demonstrated in skeletal muscle. Insulin sensitivity and glucose metabolism using ¹³C₆-glucose tracing during oral glucose tolerance tests were analyzed. We found that EAA and RET synergistically improve muscle mass and/or strength, and endurance capacity, as well as insulin sensitivity, and glucose metabolism in DEX-treated muscle. These improvements are accomplished, in part, through improvements in myofibrillar protein synthesis, NMJ, fiber type preservation, and/or mitochondrial biogenesis. In conclusion, free EAA supplementation, particularly when combined with RET, can serve as an effective means that counteracts the adverse effects on muscle of DEX that are found frequently in clinical settings.     

混凝土材料早期性能监测方法比较研究(英文)

混凝土早期硬化阶段产生的不均匀收缩是导致混凝土结构后期裂缝的主要原因之一,因此,混凝土硬化养护期的收缩应变监测对改善养护过程,控制其结构内部应变分布,保证整个建筑物的质量及安全都是非常有益的.本文运用包括埋设型光栅布拉格光纤传感器,KM系列埋设型应变传感器,热电偶温度计等三种不同传感器交叉组合了三种不同的方法对混凝土试件硬化早期的水化温度、收缩应变进行了实时监测.结果表明三种不同方法都比较精确度监测到了混凝土硬化早期的温度和收缩应变.通过对三组监测结果的分析得出了三种监测方法的优缺点,本文的研究对于混凝土早期性能监测用传感器的选择有现实的指导意义.     

Very small oxide-confined vertical microcavity lasers withhigh-contrast AlGaAs-AlxOy mirrors

We report the photo-pumped lasing action from a very small oxide-confined 870-nm vertical microcavity lasers with high-contrast AlGaAs-Al_xO_y mirrors. The effective cavity length is as small as 0.37 μm, and the oxide aperture size is 0.73 μm, estimated from the blue-shift of lasing mode due to the lateral confinement. The observed blue-shift of the lasing mode is 13.4 nm, the largest one ever reported for vertical cavity lasers. The optical losses seem to be size-independent for these small microcavity lasers. Our results indicate the possibility of the ultimate microcavity of order of λ³     

Proteomic analysis of alpha-1-antitrypsin in immunoglobulin A nephropathy

Immunoglobulin A nephropathy (IgAN) is recognized as the most common form of primary glomerulonephritis worldwide. It is characterized by mesangial cell proliferation with mesangial IgA deposition in the glomeruli, and is usually associated with secondary tubulointerstitial injury. Although significant progress has been made in the clarification of the pathogenesis of IgAN, the exact pathogenetic mechanism remains unclear. To find out the candidate proteins that play an important role in IgAN, renal cortex tissues and urine from IgAN patients were studied. The 2‐DE was performed on renal tissues of IgAN and normal controls. A series of spots identified as alpha‐1‐antitrypsin (AAT) by mass spectrometry, were found to be significantly increased in patients with IgAN. Up‐regulation of AAT variants was validated in renal cortex tissues of IgAN using Western blot and 2‐DE immunoblot. Lower isoforms (?48 kDa) and fragments (?33 kDa), suspected as cleavage forms by proteinase attack, were especially increased in IgAN compared to normal controls. In addition, AAT proteins modified by tyrosine nitration (approximately 57 and 48 kDa), which reflects excessive oxidative stress, were increased in IgAN tissue. Additionally in the urine of IgAN, increase of AAT variants and fragments was detected by 2‐DE immunoblot as well as Western blot. Immunohistochemical staining of IgAN kidney tissue revealed that the increase of AAT appeared to be derived from hypertrophic proximal tubules. The AAT staining in the glomerulus was not clear in IgAN. In addition, immunodepletion‐zymography showed a positive correlation between AAT and 80–110‐kDa proteinases in IgAN tissue. Further studies regarding the functional roles of AAT and the proteinases will allow better understanding of the pathogenesis of IgAN.