Pattern of Growth and Dry Matter Accumulation in Some Improved Cowpea Varieties (<i>Vigna unguiculata</i>) Exposed to Alpha Nano Spin

Ten (10) cowpea varieties exposed to alpha nano spin were evaluated during the 2019 cropping season to access the role of alpha nano spin in their growth and dry matter accumulation at the Botanical garden of Federal University, Lafia. A Randomized Complete Block Design (RCBD) with four replications was used. The fourth replication was used for the destructive sampling over time. The seed was exposed to alpha nano spin before planting at 0, 20, 40 and 60 minutes respectively. Results of the study showed that the varieties differed significantly with respect to morphological traits studied (P < 0.05) as exposed to the alpha nanoparticles. Morphological traits such as vine length, number of leaves and above ground stems were significantly influenced by alpha nano spin bombardment. 40 mins alpha nano spin resulted in maximum accumulation of dry matter, leaf area and leaf area index. The traits evaluated were stable under alpha nano spin exposure, suggesting that they could be useful indices in creating genetic variability in each of the varieties.

Skidding and spinning investigation for dry-lubricated angular contact ball bearing under combined loads

Sliding and spinning behaviors significantly affect the performance of rolling bearings,especially for dry-lubricated bearings,micro and macro sliding may lead to increased wear of the solid lubricating film.A unified rolling contact tribology analytical model is proposed for dry-lubricated angular contact ball bearings(ACBBs)considering the extreme conditions including high combined loads and rolling contact effects.A comprehensive solution framework is proposed to ensure the robustness of the model under different loading conditions.Equilibrium equations are solved to study the effects of friction coefficients,rotating speeds,and combined loads on the skidding and spinning characteristics of the ACBB.The results show that the rolling contact effects and combined loads significantly affect the skidding and spinning performance of the ACBB.Further analysis reveals that the skidding mechanism is related to the interaction between ball kinematical motion and traction forces.The developed analytical model is proved to more accurately predict the bearing kinematical and tribological behavior as it discards the raceway control hypothesis and considers the macro/micro-slipping,creepage,and self-spinning motions of the ball,which is validated using both the existing pure axial loading dry-lubricated ACBB model and the classical Jones–Harris model.The study would provide some guidance for the structure and lubrication design of dry-lubricated ACBBs.

静电纺再生丝素纳米纤维形态结构的研究

以98%甲酸为溶剂溶解再生丝素室温干燥膜后,采用静电纺丝纺制丝素纳米纤维;采用扫描电镜观察其形态结构;研究并分析了纺丝液质量分数、电压、喷丝头到收集网的距离、纺丝管口径对纤维直径及形态的影响。结果表明:质量分数为11%～19%的纺丝液静电纺丝均能获得丝素纳米纤维,质量分数为11%、13%,电压为32kV,固化距离为7cm时,能够获得平均直径分别为91、96nm的纳米纤维;纤维直径随纺丝液质量分数的增加而增大,随电压的增大而减小,可根据纺丝液质量分数和电压选择合适的固化距离和管口径。

电子自旋共振波谱法对干果类辐照食品的鉴定

研究电子自旋共振波谱法对干果类辐照食品的鉴定。分析开心果、核桃、桂圆的电子自旋共振波谱特征和样品干燥温度对信号强度的影响。结果表明:电子自旋共振特征峰信号强度与吸收剂量呈正相关,检测限为0.5kGy;进一步干燥时,开心果和核桃的最佳温度为40℃,桂圆的最佳温度为55℃;电子自旋共振特征峰的信号强度受微波功率影响,检测开心果、核桃、桂圆最佳的微波功率依次为0.59、0.37、0.24mW。通过电子自旋共振特征峰可判定干果是否经过辐照处理。

Drying of Flowing Liquid Film on Rotating Disk

Recently,development of high technology has been required for the formation of uniform thin film in manufacturing processes of semiconductor as the precision instruments become more sophisticated.A method called spin coating is often used for spreading photoresist on a wafer surface and drying photoresist film.In spin coating process,photoresist is uniformly spread on the wafer surface by centrifugal force caused by rotating wafer.However,it is a serious concern that streaky lines,which are caused by spiral vortices,appear on the wafer surface and prevent the formation of uniform film in the case of high rotating speed.On the other hand,in the case of low rotating speed,a small hump of the film is formed near the wafer edge.The main purpose of this study is to make clear the drying characteristics of the flowing liquid film on the rotating wafer.Temperature distribution of the flowing liquid film is captured by an infrared thermal video camera and radial gradient of the film temperature is introduced in order to evaluate the drying characteristic of the flowing film under steady state condition.Effects of the flow rate of the liquid film on the film temperature are investigated.The film temperature gradually decreases in the radial direction in all cases.At low rotating speed,the radial gradient of the film temperature is almost constant widely.On the other hand,at high rotating speed,the radial gradient of the film temperature takes a certain maximum value.It is found that the location of the gradient peak corresponds with the transition region of the air boundary layer,in which spiral vortices swirl,and shifts to the inner side of the disk with an increase of the liquid flow rate.