Exit morphology and mechanical property of FDM printed PLA: influence of hot melt extrusion process

In order to study the hot melt extrusion process in fused deposition modeling (FDM), this study mainly explores the effects of printing temperature, heated block length, feeding speed on the exit morphology and mechanical properties of FDM printed Polylactic acid (PLA) samples. High-speed camera is used to capture the exit morphology of molten PLA just extruded to the nozzle. According to exit morphology, the outlet states of extruded molten material can be divided into four categories, namely, bubbled state, coherent state, expanding state, and unstable state. Tensile test results show that printing temperature, heated block length and printing speed have significant influence on tensile properties and fracture mode of FDM printed samples. When the heated block length is 15 mm and 30 mm, there is a ductile-brittle transition in fracture mode with the increase of printing speed. The printing process window under different heated block lengths and printing temperatures has been figured out and the distribution of printing process window under different printing speeds has been discussed. There is a maximum printing process window under the heated block length of 30 mm. This finding provides a frame work for performance prediction of FDM printed parts and theoretical guidance for expanding the scope of printing process window

应用随机寡核苷酸文库修饰磁性颗粒提高血浆蛋白质的鉴定覆盖度

基于随机寡核苷酸与蛋白质之间的离子、亲和、疏水、氢键等相互作用力及多种空间结构作用,发展了一种基于随机寡核苷酸文库作为配基的新型血浆样品处理方法.采用寡核苷酸文库修饰的磁性颗粒（ MNP@ssDNA）材 料,在生理缓冲体系条件下捕获血浆样品中的蛋白质.比较了两种洗脱体系的洗脱效果,并利用nano-RPLC-ESI-MS/MS对获得的蛋白质酶解液组分进行分析.结果表明, MNP@ssDNA材料处理后的血浆蛋白质鉴定数量提升了约29. 5%,两种洗脱体系呈现良好的互补性（26.7%）.血浆中前10种高丰度蛋白质的谱图占有率从处理前的31.82%降低到21. 31% （洗脱体系1）和26.20%（洗脱体系2）.在鉴定到的蛋白质中,丰度最低的蛋白质在血浆中 的质量浓度约为0. 29ng/mL,该蛋白质仅在MNP@ssDNA材料处理后被鉴定到.结果证明MNP@ssDNA策略不仅能有效降低血浆中高丰度蛋白质的丰度,也为低丰度蛋白质的深度挖掘提供了新的思路

Morphological Characteristics and Printing Mechanisms of Grid Lines by Laser-Induced Forward Transfer

Laser-induced forward transfer (LIFT) is an innovative metallization technique used in the processing of grid lines of solar cells for the photovoltaics industry. A study on the morphology and transfer mechanisms of formed lines with high-viscosity silver paste and small gap was performed in this paper. There were three different transfer states under different laser fluences: non-transferred lines or transferred but no continuous lines, continuous transferred lines, and explosive transferred lines. There was a critical transfer threshold for the continuous line transfer under different processing speeds. Higher processing speed required a larger critical transfer threshold. The line width increased as the laser fluence increased. For all continuous formed lines, the cross-sectional morphologies with single and double peaks were shown at critical and above transfer threshold, respectively. Two symmetrical protrusions with steep edges were observed for the formed line with double peaks. By comparing the silver paste remaining on the donor and transferred to the acceptor under different laser fluences, it can be found the transferred silver paste exhibited a retracting characteristic under the critical and above transfer threshold. While a stretching characteristic was obvious when the laser fluence was much higher than the transfer threshold. Morphological characteristics with single or double peaks were determined by the distance between the rupture position of the bridge and the bottom of the bubble, under the action of the axial combined forces. This work can provide insights for improving fine-line metallization and understanding transfer mechanisms in the photovoltaic application and flexible electronics devices

应用随机寡核苷酸文库修饰磁性颗粒提高血浆蛋白质的鉴定覆盖度

基于随机寡核苷酸与蛋白质之间的离子、亲和、疏水、氢键等相互作用力及多种空间结构作用,发展了一种基于随机寡核苷酸文库作为配基的新型血浆样品处理方法.采用寡核苷酸文库修饰的磁性颗粒（ MNP@ssDNA）材 料,在生理缓冲体系条件下捕获血浆样品中的蛋白质.比较了两种洗脱体系的洗脱效果,并利用nano-RPLC-ESI-MS/MS对获得的蛋白质酶解液组分进行分析.结果表明, MNP@ssDNA材料处理后的血浆蛋白质鉴定数量提升了约29. 5%,两种洗脱体系呈现良好的互补性（26.7%）.血浆中前10种高丰度蛋白质的谱图占有率从处理前的31.82%降低到21. 31% （洗脱体系1）和26.20%（洗脱体系2）.在鉴定到的蛋白质中,丰度最低的蛋白质在血浆中 的质量浓度约为0. 29ng/mL,该蛋白质仅在MNP@ssDNA材料处理后被鉴定到.结果证明MNP@ssDNA策略不仅能有效降低血浆中高丰度蛋白质的丰度,也为低丰度蛋白质的深度挖掘提供了新的思路

Effect of Surface-Active Element Oxygen on Heat and Mass Transfer in Laser Welding of Dissimilar Metals: Numerical and Experimental Study

The effects of the surface-active element oxygen on the laser welding of 304 stainless steel (304SS) and nickel were numerically and experimentally studied in pure argon and argon-oxygen mixed gas atmospheres containing 21% oxygen (AMO). In this study, the molten pool morphology, thermal behavior, solidification phenomenon, correlation between dilution and convection flow, and microhardness of welding joints were analyzed. As a result of oxygen effects, the molten pool was deeper, the maximum temperature was higher, and the maximum flow velocity was lower in the AMO. The cooling rate (GR) and combination parameter (G/R) were studied by the direct simulation of temperature gradient (G) and solidification growth rate (R). Combined with the solidification microstructure, it was found that oxygen had little effect on grain size. The major elements Fe, Cr, and Ni within the solidified molten pool in the AMO were uniformly diluted, while the distribution of the above elements was non-homogenous in pure argon. Stronger flow and multiple directions of convection inside the molten pool contributed to uniform dilution in the AMO. The distribution of microhardness was similar to the content of Cr, and the microhardness at the substrate interface of the joint was higher in the AMO than in pure argon. The preliminary conclusions of this study provide in-depth insights into the effects of surface-active element oxygen on heat and mass transfer in laser dissimilar welding

Effect of Laser Beam Profile on Thermal Transfer, Fluid Flow and Solidification Parameters during Laser-Based Directed Energy Deposition of Inconel 718

The profile of the laser beam plays a significant role in determining the heat input on the deposition surface, further affecting the molten pool dynamics during laser-based directed energy deposition. The evolution of molten pool under two types of laser beam, super-Gaussian beam (SGB) and Gaussian beam (GB), was simulated using a three-dimensional numerical model. Two basic physical processes, the laser-powder interaction and the molten pool dynamics, were considered in the model. The deposition surface of the molten pool was calculated using the Arbitrary Lagrangian Eulerian moving mesh approach. Several dimensionless numbers were used to explain the underlying physical phenomena under different laser beams. Moreover, the solidification parameters were calculated using the thermal history at the solidification front. It is found that the peak temperature and liquid velocity in the molten pool under the SGB case were lower compared with those for the GB case. Dimensionless numbers analysis indicated that the fluid flow played a more pronounced role in heat transfer compared to conduction, especially in the GB case. The cooling rate was higher for the SGB case, indicating that the grain size could be finer compared with that for the GB case. Finally, the reliability of the numerical simulation was verified by comparing the computed and experimental clad geometry. The work provides a theoretical basis for understanding the thermal behavior and solidification characteristics under different laser input profile during directed energy deposition

苦参子提取物的抗抑郁作用机制分析

目的：探讨苦参子提取物的抗抑郁作用及其分子作用机制。方法：采用腹腔注射脂多糖（LPS）建立小鼠抑郁模型，利用旷场实验、高架十字迷宫实验和强迫游泳实验考察苦参子提取物的抗抑郁作用。苏木素-伊红（HE）染色观察小鼠海马组织病理形态变化，蛋白免疫印迹法（Western blot）检测小鼠脑组织中G_(1)/S特异性周期蛋白D_(1)（Cyclin D_(1)）、Wnt1蛋白、&beta;-连环蛋白（&beta;-catenin）、磷酸化糖原合成酶激酶-3&beta;（p-GSK-3&beta;）的蛋白表达水平。通过原位末端标记法（TUNEL）检测海马细胞凋亡情况。结果：小鼠行为学实验结果显示，与正常组相比，模型组小鼠旷场运动速度和旷场中间区运动距离，高架十字迷宫开臂停留时间均显著降低，强迫游泳实验不动时间显著增加。与模型组相比，苦参子提取物中、高剂量组小鼠旷场实验旷场运动速度增加（P&lt;0.05），高剂量组小鼠旷场中间区运动距离增加（P&lt;0.05），中剂量组及高剂量组高架十字迷宫开臂停留时间增加（P&lt;0.05，P&lt;0.01），强迫游泳实验不动时间降低（P&lt;0.01）；与模型组比较，苦参子中、高剂量组小鼠脑组织中Wnt1和&beta;-catenin蛋白表达水平均显著增加（P&lt;0.01，P&lt;0.01）。TUNEL染色结果显示，模型组小鼠的海马细胞凋亡率较正常组显著增加（P&lt;0.01），与模型组比较，苦参子中、高剂量组小鼠海马细胞凋亡率显著降低（P</p