电催化氮气还原合成氨催化材料研究进展

氨是纺织、制药、化肥等领域重要的化工原料,也是一种清洁的能源载体,需求量大。目前氨的工业生产主要为Haber-Bosch法,反应条件严苛,能源消耗大且碳排放较高。电催化氮气还原(NRR)合成氨是一种在常温常压下进行的反应,工作电位低,且电能可通过清洁能源提供,是一种很有潜力的合成氨新工艺。但目前电催化NRR材料的产氨速率和法拉第效率低、工作稳定性不够高、溶液中痕量氨的定量检测困难及检测标准不统一等都为其发展带来了巨大挑战。本文首先介绍了电催化NRR的反应机理和常用研究方法,然后重点梳理了2019年以来NRR催化材料的最新研究进展,最后对该领域研究面临的挑战和机遇进行了展望。     

The Potential Role of the Methionine Aminopeptidase Gene PxMetAP1 in a Cosmopolitan Pest for Bacillus thuringiensis Toxin Tolerance

Methionine aminopeptidases (MetAPs) catalyze the cleavage of the N-terminal initiator methionine (iMet) in new peptide chains and arylamides, which is essential for protein and peptide synthesis. MetAP is differentially expressed in two diamondback moth (DBM; Plutella xylostella) strains: the G88 susceptible strain and the Cry1S1000 strain, which are resistant to the Bt toxin Cry1Ac, implicating that MetAP expression might be associated with Bt resistance. In this study, we identified and cloned a MetAP gene from DBMs, named PxMetAP1, which has a CDS of 1140 bp and encodes a 379 amino acid protein. The relative expression of PxMetAP1 was found to be ~2.2-fold lower in the Cry1S1000 strain compared to that in the G88 strain. PxMetAP1 presents a stage- and tissue-specific expression pattern, with higher levels in the eggs, adults, integument, and fatbody of DBMs. The linkage between PxMetAP1 and Cry1Ac resistance is verified by genetic linkage analysis. The knockout of PxMetAP1 in G88 by CRISPR/Cas9 leads to a ~5.6-fold decrease in sensitivity to the Cry1Ac toxin, further supporting the association between the PxMetAP1 gene and Bt tolerance. Our research sheds light on the role of MetAP genes in the development of Bt tolerance in P. xylostella and enriches the knowledge for the management of such a cosmopolitan pest.     

一些建材中的天然放射性水平

继对浙江省建筑材料中的~(226)Ra、~(232)Th 和~(40)K 水平进行调查~([1])之后,1982—1983年我们对国内建材中的上述三种核素的水平作了调查。所调查的建材除了常用建材如红砖、水泥外,还对一些在建材生产中颇有潜力的工业废渣和用工业废渣生产的建材成品进行了调查。     

脉冲TIG焊熔宽动态过程模糊推理——神经网络控制方法

对脉冲ＴＩＧ焊工艺中焊接电流－正面熔宽动态过程提出了一种模糊神经网络控制方法，并研究了利用人工神经网络直接过程建模的控制仿真，从而回避了经典方法对过程建模控制和困难。将上述方法用于实际脉冲ＴＩＧ焊过程控制，结果表明模糊神经网络控制方案有效。     

引水改善平原感潮河网水质效果评估

以张家港市三大水循环体系为例,构建一维河网水动力水质数学模型,揭示了不同长江潮位与内河引水量的响应关系,不同引水量与河网水质改善效果、引水服务面积的响应关系。结果表明:随着长江高潮位的升高,内河引水量呈现线性增长趋势;当中部水系引水量达到1.4×10~7m~3时,氨氮浓度改善率达到50%以上,浓度变化指数达到0.6以上,且整体提升了1个水质类别;引水服务面积随着引水量的增大呈现线性增长趋势,而单位引水量服务面积呈现对数函数下降趋势,其中东北部水系单位引水量服务面积最大,为0.352～0.891 km~2/万m~3。     

皖西祠堂建筑特征探究

皖西祠堂作为具有地域特色的建筑类型,近年来得到越来越多的关注,根据对皖西祠堂的调研测绘,探索其选址和布局、空间特征、立面造型和构造装饰,总结出皖西祠堂建筑特征及其鲜明的地域特色。为后人研究皖西祠堂的特征、形成和发展提供支持,同时对皖西祠堂的利用和保护提出意见。     

Preparation of monophasic titanium sub-oxides of Magnéli phase with enhanced thermoelectric performance

Titanium sub-oxides of Magnéli phase are considered as earth-abundant, non-toxic materials for thermoelectric application at high temperature, but very limited investigation has been reported mainly owing to the difficulty lying in obtaining monophasic material. Herein we describe a facile strategy to prepare monophasic Ti₉O₁₇ and Ti₄O₇ powder, in which the single Ti₉O₁₇ phase is obtained for the first time. After spark plasma sintering, the thermoelectric properties of monophasic Ti₉O₁₇ and Ti₄O₇ ceramics are studied comparatively. Despite the one magnitude lower electrical conductivity, Ti₉O₁₇ shows higher power factor compared with Ti₄O₇ due to the large Seebeck coefficient. Moreover, with the low electronic thermal conductivity, sub-micron scaled grain size and nano-scaled crystallographic shear plane, the Ti₉O₁₇ ceramic exhibits even lower thermal conductivity compared to Ti₄O₇, leading to a ZT of 0.16 at 764 K, which is the best thermoelectric performance among reported Magnéli phases.     

Double-Lock Nanomedicines Enable Tumor-Microenvironment-Responsive Selective Antitumor Therapy

A hybrid nanocarrier for reducing the off-target adverse effects of chemotherapy via selective drug delivery to the tumor cells is reported. The model active agent, combretastatin A4 (CA4) phosphate is deposited onto the magnetite (Fe₃O₄) nanoparticles as the core, followed by lipid coating as the shell. Upon nanocarrier administration and biodistribution to the tumor site, the high level of adenosine triphosphate in the extracellular space of tumor induces the cargo release via phosphate displacement. Then, the CA4 phosphate is dephosphorylated by the alkaline phosphatase that is overexpressed at the plasma membrane of certain tumor cells, resulting in enhanced intracellular uptake of hydrophobic CA4. These sequential two-step unlocking processes enable the preferable accumulation of CA4 within tumor cells. Such approach is applicable to a wide range of chemotherapeutics and is promising for efficacy enhancement and side-effect reduction of antitumor chemotherapy.     

陀螺经纬仪自适应智能下放系统

自动下放系统一直是牵制陀螺经纬仪全自动化进程的关键环节。针对现有陀螺仪,提出基于旋转步进电动机驱动陀螺仪凸轮轴的自动下放方案,设计下放结构及总控制系统,分析影响陀螺下放摆幅的决定性因素,通过大量试验总结出下放摆幅在理想范围时半脱位置与光标初始位置的关系,基于此提出自适应智能运动控制系统,即根据光标初始位置与半脱位置的关系曲线建立下放速度方案数据库,对不同的光标初始位置自动查询相应的半脱位置设置电动机速度从而实现智能控制。通过对自动下放系统进行平稳性、下放摆幅及重复性对比试验,表明该系统有效可靠,实现陀螺在不同托起状态下均能下放在正常工作区域,且陀螺运行平稳,有效地解决自动下放限幅的瓶颈,显著地提高自动化程度和测量精度。     

空间治理视角下中大北门广场碎片化现象研究

中国城市建设进入存量发展时期，很多城市小尺度公共空间在城市更新过程中被重构、分割和消解，出现完整性和适应性受损的碎片化现象。通过对中山大学北门广场改造事件的实地调研、资料研究和分析、演绎等，从空间治理角度探究城市小尺度公共空间碎片化的成因：规划决策中缺乏有效的公众参与沟通机制，自上而下的操作模式僵化，本位主义的使用模式缺乏疏导。民众推脱维护公共空间秩序的责任的同时，主管部门缺乏对公共空间的策划、评估、监管和沟通，最终形成“公地悲剧”。基于以上分析实证，提出改进城市小尺度空间碎片化现象的策略建议。