Matrix Manipulation of Directly-Synthesized PbS Quantum Dot Inks Enabled by Coordination Engineering

The direct-synthesis of conductive PbS quantum dot (QD) ink is facile, scalable, and low-cost, boosting the future commercialization of optoelectronics based on colloidal QDs. However, manipulating the QD matrix structures still is a challenge, which limits the corresponding QD solar cell performance. Here, for the first time a coordination-engineering strategy to finely adjust the matrix thickness around the QDs is presented, in which halogen salts are introduced into the reaction to convert the excessive insulating lead iodide into soluble iodoplumbate species. As a result, the obtained QD film exhibits shrunk insulating shells, leading to higher charge carrier transport and superior surface passivation compared to the control devices. A significantly improved power-conversion efficiency from 10.52% to 12.12% can be achieved after the matrix engineering. Therefore, the work shows high significance in promoting the practical application of directly synthesized PbS QD inks in large-area low-cost optoelectronic devices.     

Influence of the Impaction Angle on the Triboelectric Charging of Aerosol Nanoparticles

A low pressure impactor is used to measure triboelectric charging behavior of metallic nanoparticles. Ag nanoparticles, produced by spark discharge, were impacted onto Pt sputtered targets. The influence of the impaction angle and impaction velocity on the triboelectric charging was investigated. While for perpendicular impaction the charge transfer behavior of previous work was confirmed, the oblique impaction revealed new phenomena. Additional charge transfer was observable, which increases with obliqueness. The possibility of mass transfer between particle and target due to the high-energy collisions was also investigated. SEM characterization and Auger spectroscopy indicate mass transfer from the particle to the target surface.     

SBS Thermoplastic Elastomer Based on Dynamic Metal-Ligand Bond: Structure,Mechanical Properties,and Shape Memory Behavior

A Cooper(II) (Cu²⁺)-nitrogen coordination-crosslinked network is designed in poly(styrene-co-butadiene-co-styrene) (SBS) to change commercial elastomers into advanced soft materials. Herein, ligand groups into SBS molecular chains by the 3,6-di(2-pyridyl)-1,2,4,5-tetrazine (DPT) click reaction are first introduced. The results from fourier transform infrared (FT-IR), 1H-nuclear magnetic resonance, and X-ray photoelectron spectroscopy (XPS) are verified the successful modification of SBS. The DPT-grafted SBS could then coordinate with copper sulfate (CuSO₄) to form a Cu²⁺-nitrogen bond, which is further characterized using FT-IR, XPS, atomic force microscope, scanning electron microscope, and geometric structure calculations. After modifying SBS to form an SBS-DPT/CuSO₄ composite (SBS-DPT2-Cu10), the tensile stress is improved from 11.43 to 23.25 MPa, while the elongation at break is remained almost unchanged, and the corresponding toughness is increased from 33.21 to 63.26 MJ m^–3. Moreover, the dynamic nature of the Cu²⁺-nitrogen coordination bonds enables the SBS-DPT/CuSO₄ composite to exhibit sustained thermoplastic performance and excellent shape memory behavior under an external thermal stimulus.     

我国水-能源-粮食耦合关系及影响因素

为缓解我国水、能源和粮食资源紧张问题，促进资源可持续利用，构建水-能源-粮食系统，利用耦合协调度模型对我国的30个省（自治区、直辖市）进行测算,并利用空间杜宾模型分析主要影响因素。结果表明：2003—2017年，我国能源、粮食评价[JP]指数高于水资源评价指数，系统综合评价指数逐年递增；大部分省份耦合协调度处于初级协调水平且呈现逐年上升的态势，个别省份耦合协调度濒临失调；耦合协调度空间自相关性较强，虽有明显波动，但是呈现逐年加强的态势；影响耦合协调度的主要因素有从业人口数、固定资产投资额、人均生产总值、人口总数、[JP]文盲人口占比、工业污染排放、城镇化。     

Comparative study of embrittlement of quenched and tempered steels in hydrogen environments

The study of steels which guarantee safety and reliability throughout their service life in hydrogen-rich environments has increased considerably in recent years. Their mechanical behavior in terms of hydrogen embrittlement is of utmost importance. This work aims to assess the effects of hydrogen on the tensile properties of quenched and tempered 42CrMo4 steels. Tensile tests were performed on smooth and notched specimens under different conditions: pre-charged in high pressure hydrogen gas, electrochemically pre-charged, and in-situ hydrogen charged in an acid aqueous medium. The influence of the charging methodology on the corresponding embrittlement indexes was assessed. The role of other test variables, such as the applied current density, the electrolyte composition, and the displacement rate was also studied. An important reduction of the strength was detected when notched specimens were subjected to in-situ charging. When the same tests were performed on smooth tensile specimens, the deformation results were reduced. This behavior is related to significant changes in the operative failure micromechanisms, from ductile (microvoids coalescence) in absence of hydrogen or under low hydrogen contents, to brittle (decohesion of martensite lath interfaces) under the most stringent conditions.     

Strain rate dependence of the contribution of surface diffusion to bulk sintering viscosity

Modeling of bulk sintering viscosity usually neglects the contribution of pore surface diffusion with respect to grain-boundary diffusion. This approximation is questionable at the high densification rates used today in advanced fast sintering techniques. A two-dimensional analysis of the problem shows that the influence of surface diffusion on bulk viscosity at high strain rate can be decomposed as the sum of two terms: a term linked to the change in pore surface curvature and a term linked to the change in grain-boundary size. The computational procedure relies on the partition of pore profile evolution into a transient component accounting for non-densifying phenomena and an asymptotic component accounting for strain-rate-controlled phenomena. The largest impact of surface diffusion is found to arise from the change in grain-boundary size. It follows a transition from Newtonian viscosity at low strain rate to non-Newtonian viscosity which, during densification, increases nearly linearly with strain rate. In some conditions, viscosity can then reach more than twice the value estimated when neglecting pore surface diffusion. Reversely, expansion is accompanied by a decrease in grain-boundary size which causes a decrease in viscosity and can lead to grain separation at high strain rate.     

基于柠檬酸-铕纳米配位聚合物构建荧光探针快速检测汤煲中5’-肌苷酸含量

基于柠檬酸-铕金属有机纳米配体聚合物（citrate/europium lanthanide coordination polymer nanoparticles，Cit/Eu LCP NPs）构建快速检测肉品汤煲中5’-肌苷酸（inosine-5’-monophosphate，5’-IMP）的荧光探针。研究结果表明，5’-IMP对Cit/Eu?LCP?NPs有良好的荧光猝灭作用。在最佳条件下，该荧光探针在5’-IMP?2.5～200?μg/mL的质量浓度范围内呈现出良好的线性关系，检出限为0.17?μg/mL，且具备良好的抗干扰、稳定性和重复性。为了验证方法可行性，将该方法应用于实际鸡汤样品中的5’-IMP检测，测得加标回收率为97.85%～103.95%，可为快速检测肉品汤煲中5’-IMP提供新的思路和方法。     

氮杂环卡宾-钯功能化的配位聚合物（NHC-Pd@Zn-L）：合成、表征及催化Suzuki-Miyaura交叉偶联反应

以\mathrm{1,3}-二(1-羧乙基)咪唑盐(HL)和Zn(NO₃)₂·6H₂O反应合成二维配位聚合物[Zn(L)₂] _n (Zn-L)，产物再与K₂PdCl₄在四氢呋喃溶液中反应引入氮杂环卡宾-钯（NHC-Pd）催化位点，制得催化剂NHC-Pd@Zn-L，并通过PXRD、TGA、ICP、SEM、EDS和XPS进行表征。结果表明，NHC-Pd@Zn-L具有良好的热稳定性且修饰后晶体的框架结构没有发生变化，Pd以NHC-Pd的形式结合在Zn-L中，并均匀分散在配位聚合物中。将NHC-Pd@Zn-L用于催化Suzuki-Miyaura交叉偶联反应，当以苯硼酸和溴苯为底物，催化剂用量为15 mg，乙醇为溶剂，碳酸钾为碱的条件下60℃反应6 h，产率达到>99%，而且催化剂易于回收并可循环使用3次。     

并联混合动力汽车能量管理与转矩协调控制策略

研究并联混合动力汽车的控制策略。基于发动机输出转矩最优的能量管理策略,对并联混合动力汽车在工作模式切换中的相互配合问题,提出发动机动态转矩控制+动力电池荷电状态(state of charge,SOC)干预+电机转矩补偿控制的转矩协调控制方法;在Matlab/Simulink/Stateflow平台搭建整车能量管理控制策略模型,控制发动机工作在高效率区,保证发动机输出最优转矩;根据电池的SOC干预电机的运行状态,协同发动机提供整车需求转矩。在Cruise平台下建立整车模型,以新欧洲驾驶周期作为循环工况进行离线仿真。结果表明,能量管理与转矩协调控制策略能够有效分配电机和发动机的转矩输出,满足混合动力汽车多模式切换的要求。