不同孔形下豆类透筛效果对比及圆筒筛优化

以大豆为对象,推导了筛孔透筛区域的面积计算公式,对比了不同孔型圆筒筛的大豆透筛效果,得出大豆在正方形筛孔的圆筒筛中透筛效果最好,并通过仿真计算对其进行了验证。在此基础上对正方形筛孔的圆筒筛进行优化,用筛分比和除杂比计算筛分效果,通过正交仿真试验分析得到不同工艺参数对圆筒筛的豆类筛分效果的影响次序,并得出最佳工艺参数为圆筒倾角5°、圆筒转速16r/min、进料速度14t/h、筛孔边长9mm,该条件下筛分效果为0.935,比原始模型提高了3.89%。     

低碳钢电弧熔覆增材层摩擦磨损及抗腐蚀性能

目的 针对低碳钢零件的破损失效采用TIG焊电弧熔覆增材制造工艺，研究低碳钢电弧熔覆修复使其达到再制造零件性能要求的可行性，为实现TIG焊修复应用提供保证。方法 通过TIG焊熔覆在低碳钢坡口处，对熔覆接头的显微组织进行分析，并测试修复后的增材层表面硬度性能。使用Nanovea Tribometer摩擦磨损仪和NanoveaPS50表面轮廓仪，对基体和增材层进行摩擦性能测试，并表征摩擦磨损后的表面形貌，探究磨损机理。采用电化学工作站对基体和增材层的腐蚀性能进行分析。结果 修复后的增材层显微硬度（220.17HV）高于基体且其摩擦性能和腐蚀性能优于基体，随着磨损载荷的增加，增材层的摩擦系数逐渐降低，磨损机制主要为磨粒磨损和粘着磨损。增材层表面组织均匀细小，在NaCl溶液中点蚀坑小且分散，增材层的腐蚀电流密度（1.8349×10-6 A/cm2）小于基体的腐蚀电流密度（6.5251×10-5 A/cm2），增材层表面的抗腐蚀能力明显提高。结论 电弧熔覆低碳钢可满足低碳钢零部件现场电弧快速修复对再制造性能的要求，实现了低碳钢破损零部件的表面修复与强化。     

Computer-based engineering of thermostabilized antibody fragments

We used the molecular modeling program Rosetta to identify clusters of amino acid substitutions in antibody fragments (scFvs and scAbs) that improve global protein stability and resistance to thermal deactivation. Using this methodology, we increased the melting temperature (T_m) and resistance to heat treatment of an antibody fragment that binds to the Clostridium botulinum hemagglutinin protein (anti-HA33). Two designed antibody fragment variants with two amino acid replacement clusters, designed to stabilize local regions, were shown to have both higher T_m compared to the parental scFv and importantly to retain full antigen binding activity after 2 hr of incubation at 70°C. The crystal structure of one thermostabilized scFv variants was solved at 1.6 Å and shown to be in close agreement with the RosettaAntibody model prediction.     

基于壳聚糖多孔碳的制备及电容性能研究

以壳聚糖为碳源和氮源,采用预碳化处理和KOH活化两步法制备了壳聚糖多孔碳材料,考察了活化剂KOH用量对电极材料形貌、结构以及电容性能的影响。结果表明:当KOH与预碳化壳聚糖质量比为0.6∶1时,制备的多孔碳材料KOH-CTS-0.6具有最优的电化学性能。KOH-CTS-0.6具有大比表面积(1 348 m~2·g~(-1)),含有丰富的N、O元素(2.9%N和7.4%O)。在电流密度为0.5 A·g~(-1)时,KOH-CTS-0.6的比电容为235.2 F·g~(-1),显示出优秀的倍率能力;在电流密度为10 A·g~(-1)的大电流时,其比电容依然高达178.6 F·g~(-1)。此外,该材料还具有良好的循环稳定性,500次循环后比电容保持率为94%。     

分子筛脱水吸附塔的结构应力与疲劳分析

综合考虑分子筛脱水吸附塔的结构、疲劳状况及管口载荷等因素,利用ANSYS对吸附塔进行结构应力与疲劳分析。计算结果表明:所建立的吸附塔整体模型合理;该结构在确保可靠性的基础上可降低制造成本;该设备能满足疲劳寿命的要求。     

Research on the identification performance of UHF RFID system considering the correlation of cascaded channel

The identification rate of UHF RFID system was restricted by multipath propagation effects.The system identification performance was studied considering the correlation coefficient between forward and reverse channels.Based on the generalized Rician fading channel model,the analytical expression of identification rate was derived under independent,full correlation and correlation cases.Compared with the existing analysis,the proposed uniform calculation formula of identification rate was for any correlation coefficient and kinds of channel conditions.The numerical computation and Monte-carlo simulations show that the influences of different correlation coefficients,channel conditions,sensitivity and distance on the identification rate.     

Phase stability and thermo-physical properties of ZrO2-CeO2-TiO2 ceramics for thermal barrier coatings

The properties of ZrO₂ co-stabilized by CeO₂ and TiO₂ ceramic bulks were investigated for potential thermal barrier coating (TBC) applications. Results showed that the (Ce_0.15Ti_x)Zr_0.85-xO7 (x?=?0.05, 0.10, 0.15) compositions with single tetragonal phase were more stable than the traditional 8YSZ at 1573?K. These compositions also showed a large thermal expansion coefficient (TEC) and a high fracture toughness, which were comparable to those of YSZ. However, the phase stability, fracture toughness and sintering resistance of the CeO₂-TiO₂-ZrO₂ system showed a decline tendency with the increase of TiO₂ content. The TEC of the ceramic bulks decreased with increase of TiO₂ content as well because the crystal energy was enhanced with increasing substitution of Zr⁴⁺ by smaller Ti⁴⁺. The (Ce_0.15Ti_0.05)Zr_0.8O₂ had the best comprehensive properties among the (Ce_0.15Ti_x)Zr_0.85-xO₂ compositions as well as a low thermal conductivity. Therefore, it can be explored as a TBC candidate material for high-temperature applications.     

Polyurethane/doxorubicin nanoparticles based on electrostatic interactions as pH‐sensitive drug delivery carriers

In order to obtain a pH‐sensitive delivery carrier for doxorubicin (DOX), DOX‐loaded polyurethane (PU·DOX) nanoparticles were readily prepared in water by electrostatic interactions between amphiphilic polyurethane with carboxyl pendent groups (PU‐COOH) and doxorubicin hydrochloride (DOX·HCl). The structures of the products obtained were characterized by Fourier transform infrared spectroscopy, ¹H NMR spectroscopy, gel permeation chromatography, UV–visible spectroscopy, dynamic light scattering and transmission electron microscopy. The average hydrodynamic size of the PU·DOX nanoparticles was around 182 nm with negative surface charge (?1.1 mV) and a spherical or rodlike shape. PU·DOX nanoparticles had a higher drug‐loading content of 14.1 wt%. The in vitro drug release properties of PU·DOX nanoparticles were investigated at pH 4.0, 5.0 and 7.4, respectively. PU·DOX nanoparticles exhibited a good pH‐sensitive drug release property, but there was almost no release of DOX from PU·DOX nanoparticles at pH 7.4. The in vitro cellular uptake assay and the Cell Counting Kit‐8 assay demonstrated that PU·DOX nanoparticles had a higher level of cellular internalization and higher inhibitory effects on the proliferation of human breast cancer (MCF‐7) cells than pure DOX. The enhancement of the inhibition effects resulted from increasing apoptosis‐inducing effects on MCF‐7 cells, which was related to the enhancement of Bax expression and the reduction of Bcl‐2 expression confirmed by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay, real‐time polymerase chain reaction (PCR) assay and western blot assay. © 2018 Society of Chemical Industry     

透明红外硫系薄膜非均匀性检测及影响因素

薄膜非均匀性的无损检测对于制备大面积高质量的红外透明薄膜尤为重要。针对红外薄膜光学均匀性难以获取的困难,提出了一种同时获得单层透明红外薄膜厚度和折射率均匀性的无损检测方法。实验上,通过磁控溅射法在二氧化硅衬底上制备了厚度约1.4μm红外透明Ge-Sb-Se硫系薄膜,然后在该薄膜上标定出36个80μm×80μm区域,利用显微傅里叶红外光谱仪测得该36个区域的透射谱,通过分段滤波的方法滤除背景噪声,运用改进的Swanepoel方法计算得到了薄膜每一个区域的厚度和折射率,进而精确获得该薄膜的厚度和折射率均匀性,结果表明精度优于0.5%。