轻组分绝对占优的蒸汽再压缩隔离壁蒸馏塔的最优拓扑结构

隔离壁蒸馏塔（DWC）的双塔多段拓扑结构导致蒸汽再压缩热泵（VRHP）的应用具有多种可能性,包括单VRHP、多VRHP、多级VRHP以及它们的相互组合等复杂结构,这显著加剧了蒸汽再压缩隔离壁蒸馏塔（DWC-VRHP）综合与设计的复杂性与烦琐性。为解决这一问题,针对轻组分绝对占优的三元宽沸点物系的分离问题推演了DWC-VRHP的最优拓扑结构,由此能够有效回避系统综合与设计过程中的结构搜索问题并显著降低模型化与搜索计算的工作强度。轻组分绝对占优与宽沸点物性导致了塔顶冷凝器与预分离蒸馏塔的提馏段是主要的热源与热阱,也决定了DWC-VRHP的最优拓扑结构,即一个二级VRHP与DWC的耦合系统。第一级VRHP用于进料预热,既充分利用温度提升跨度小的特点,又可以通过进料分流强化气液相间的物质传递。第二级VRHP用于加热预分离蒸馏塔的提馏段（或公共提馏段）,能够最大限度地降低分离操作的非可逆性。采用苯/甲苯/邻二甲苯和正戊烷/正己烷/正庚烷两个物系的分离问题对所提出的DWC-VRHP的最优拓扑结构进行了分析与验证。通过与DWC以及DWC-VRHP其他潜在结构的系统性比较,显示了所提出系统结构在稳态性能方面的优越性。     

电磁感应加热技术在轮胎硫化机上的应用研究

研究电磁感应加热技术(简称电磁加热)在轮胎硫化机上的应用。在轮胎硫化机线圈板上开设若干圆孔以放置电磁线圈,并在线圈板上下设置隔热板,热板产生涡电流而感应生热,热量由热板传递到模具,实现对轮胎的硫化。电磁加热硫化可以保证轮胎硫化温度均匀,并节约能源,大幅提高轮胎的硫化质量。     

用SiO2微粉制备碳化硅粉体的研究

为回收利用SiO2微粉,探究了以SiO2微粉为原料通过碳热还原法制备碳化硅粉体的最佳工艺条件;研究了分别以石油焦、活性炭和石墨粉为还原剂对冶炼效果的影响。在最佳碳质还原剂的基础上,研究了不同配碳比(还原剂与SiO2微粉的质量比为1∶3.5、1∶3、1∶2.5、1∶2、1∶1.5)和不同冶炼时间(15、30、45、60 min)对冶炼效果的影响。结果表明:石油焦、活性炭、石墨粉3种碳质还原剂中,石油焦的冶炼效果最佳;将石油焦与原料SiO2微粉以质量比1∶2进行混合,在中频感应炉中以1650℃冶炼45 min为最佳冶炼工艺条件;以此能够得到晶粒生长较好、品质较高的碳化硅粉体,碳化硅含量高达93.50%(w)。     

光伏废料制备Si3N4-SiC材料的抗氧化性和抗侵蚀性

将光伏废料经酸洗除杂后,与硅粉按85∶15的质量比配料,以聚乙二醇做结合剂,成型为10 mm×10 mm×20 mm的生坯后,在1380℃保温2 h氮化制成Si3N4-SiC材料,然后研究了该Si3N4-SiC材料的抗氧化性和抗侵蚀性。结果表明:1)制备的Si3N4-SiC材料在空气气氛中抗氧化性较好,主要是由于其氧化产物Si2N2O和SiO2填充气孔,促进烧结,提高了试样的致密度。2)在静态熔盐(Na3AlF6)中的抗侵蚀性能较好,主要是由于Na3AlF6渗入气孔中,使其显气孔率降低。3)在动态熔盐中的抗侵蚀性相对变差,主要是由于CO2气体的搅拌和对Si3N4、SiC的氧化二者共同作用的结果。     

纳米NiO掺杂Carbores'P对Al2O3-C耐火材料力学性能的影响

为提高低碳铝碳耐火材料的力学性能,以≤1 mm的棕刚玉、Si粉和Carbores’P为原料,外加纳米NiO为催化剂,制备Al2O3-C基质试样,利用XRD、SEM、激光拉曼光谱研究纳米NiO对Carbores’P炭化产物的影响。以棕刚玉(粒度为5~3、3-1、≤1 mm)、电熔白刚玉粉、Si粉、鳞片石墨、Carbores’P、纳米NiO为原料制备低碳Al2O3-C试样,研究纳米NiO掺杂Carbore’P对试样力学性能的影响。结果表明:1400℃埋碳热处理后,添加纳米NiO能提高基质的石墨化度,促进碳纳米管和SiC晶须的生成;正是由于它们的生成,提高了Al2O3-C试样的致密度、常温强度和断裂前的位移量,使试样韧性增强。     

Engineered pH-inducible intein Mtu ΔI-CM variants with markedly reduced premature cleavage activity

Inteins have been widely exploited for the purification of tagless proteins. Among them, pH-inducible C-terminal-cleavage inteins enable the preparation of proteins and peptides with an authentic N-terminus. However, a severe premature cleavage around neutral pH has limited the application of these inteins, especially when used in recombinant hosts such as Escherichia coli. By targeting the microenvironment of the two key histidine residues H429 and H439, we engineered Mtu ΔI-CM intein to markedly reduce its premature cleavage. Kinetic analyses suggested that although the variants retained the pH dependence, they indeed cleaved slower, especially at pH 7.6. These variants resulted in higher yields for two model polypeptides than the original Mtu ΔI-CM intein, when used in conjunction with a cleavable self-assembling tag. This work suggests that more controllable pH-inducible inteins can be obtained by manipulating the residues in the self-cleavage sites and provide better performance for tag-based protein preparation strategies.     

A novel flow field with controllable pressure gradient to enhance mass transport and water removal of PEM fuel cells

An easily machined novel flow field with controllable pressure gradient across adjacent channels was designed and a two dimensional, across-the-channel, two-phase model was developed to study the gas transport and water removal of the novel configuration. The effect of channel-rib width ratio, GDL thickness and pressure gradient on the profiles of oxygen concentration and water saturation within the GDL were investigated. Special attention was paid to the mechanisms of the promoted mass transport and water removal rates under a pressure gradient. The model was validated by experiments with various channel-rib ratios and GDL thicknesses at different operating pressure. The results revealed that, oxygen concentration was increased, and the water saturation was reduced under the rib with a pressure gradient generated across the adjacent channels. The optimal pressure gradient is between 0.1 to 0.2 atm for the studied channel geometry and configuration. The mechanisms of the improved cell performance were elucidated.     

Sintering behavior of a nanostructured thermal barrier coating deposited using electro-sprayed particles

During high temperature service, a series of microstructure and phase evolutions occur in thermal barrier coatings (TBCs), which result in degradation of thermal insulation and durability. In this study, the sintering behavior of an air plasma sprayed 8 wt% YSZ coating deposited using electro-sprayed nanostructured particles (ESP) as feedstock powder was investigated and compared with conventional YSZ coating deposited using hollow spherical powders (HOSP). Due to the distinct asymmetric porous structure formed by nanosized YSZ particles, the ESP powder was partially melted in the plasma jet during the deposition, which resulted in the formation of a nanostructured coating that consisted of porous nanozones and dense zones. The ESP coating not only shows a significantly lower initial thermal conductivity of 0.70 W/mK, but also exhibits a stronger sintering resistance in terms of phase stability and thermal insulation compared to the conventional coating. When subjected to prolonged sintering at 1400°C for 128 hours, the thermal conductivity of the ESP coating would gradually increase to about half that of the HOSP coating at 1.29 W/mK. These differences are ascribed to the interaction among different sintering behavior between nanozones and dense zones.     

A novel efficient RhB absorbent of Mo2N/MoO2 composite nanofibers for wastewater treatment

Mo₂N/MoO₂ composite nanofibers have been prepared via an electrospinning and controlled nitridation process. The composite nanofibers exhibit a highly efficient Rhodamine B (RhB) absorption behavior with a rate constant of 0.153 g min⁻¹ mg⁻¹, which is about 20 times of the commercial-activated carbon material. Furthermore, the nanofibers show stable absorption activity after recycled by an environmental friendly procedure for four times. The excellent absorption performance of Mo₂N/MoO₂ composite nanofibers demonstrates a promising application of Mo₂N-related materials as an absorbent for wastewater treatment.