PVDF-assisted pyrolysis strategy for corrugated plate oxygen electrocatalysis nanoreactor:Simultaneously realizing efficient active sites and rapid mass transfer

Though Zn-air batteries(ZABs)are one of the most promising system for energy storage and conversion,challenge still persists in its commercial application due to the sluggish kinetics of oxygen reduction/evolution reaction(ORR/OER).Hereby,a polyvinylidene fluoride(PVDF)-assisted pyrolysis strategy is proposed to develop a novel corrugated plate-like bifunctional electrocatalyst using two-dimensional zeolitic imidazolate frameworks(2D ZIF-67)as the precursor.The employed PVDF plays an important role in inheriting the original 2D structure of ZIF-67 and modulating the composition of the final products.As a result,a corrugated plate-like electrocatalyst,high-density Co nanoparticles decorated 2D Co,N,and F tri-doped carbon nanosheets,can be obtained.The acquired electrocatalyst enables efficient active sites and rapid mass transfer simultaneously,thus showing appreciable electrocatalytic performance for rechargeable Zn-air batteries.Undoubtedly,our proposed strategy offers a new perspective to the design of advanced oxygen electrocatalysts.

Regulating the interfacial charge transfer and constructing symmetry-breaking sites for the enhanced N_(2) electroreduction activity

The Haber-Bosch process for industrial NH_(3) production is energy-intensive with heavy CO_(2) emissions.Electrochemical N_(2) reduction reaction(NRR)is an attractive carbon-neutral alternative for NH_(3) synthesis,while the challenge associated with N_(2) activation highlights the demand for efficient electrocatalysts.Herein,we demonstrate that PdCu nanoparticles with different Pd/Cu ratios anchored on boron nanosheet(PdCu/B)behave as efficient NRR electrocatalysts toward NH_(3) synthesis.Theoretical and experimental results confirm that the highly efficient NH_(3) synthesis can be achieved by regulating the charge transfer between interfaces and forming a symmetry-breaking site,which not only alleviates the hydrogen evolution but also changes the adsorption configuration of N_(2) and thus optimizes the reaction pathway of NRR over the separated Pd sites.Compared with monometallic Pd/B and Cu/B,the PdCu/B with the optimized Pd/Cu ratio of 1 exhibits superior activity and selectivity for NH_(3) synthesis.This study provides new insight into developing efficient catalysts for small energy molecule catalytic conversion via regulating the charge transfer between interfaces and constructing symmetry-breaking sites.

The Beishan underground research laboratory for geological disposal of high-level radioactive waste in China:Planning, site selection,site characterization and in situ tests

With the rapid development of nuclear power in China, the disposal of high-level radioactive waste（HLW） has become an important issue for nuclear safety and environmental protection. Deep geological disposal is internationally accepted as a feasible and safe way to dispose of HLW, and underground research laboratories（URLs） play an important and multi-faceted role in the development of HLW repositories. This paper introduces the overall planning and the latest progress for China＇s URL. On the basis of the proposed strategy to build an area-specific URL in combination with a comprehensive evaluation of the site selection results obtained during the last 33 years, the Xinchang site in the Beishan area,located in Gansu Province of northwestern China, has been selected as the final site for China＇s first URL built in granite. In the process of characterizing the Xinchang URL site, a series of investigations,including borehole drilling,geological mapping, geophysical surveying,hydraulic testing and in situ stress measurements, has been conducted. The investigation results indicate that the geological,hydrogeological, engineering geological and geochemical conditions of the Xinchang site are very suitable for URL construction. Meanwhile, to validate and develop construction technologies for the Beishan URL, the Beishan exploration tunnel（BET）, which is a 50-m-deep facility in the Jiujing sub-area, has been constructed and several in situ tests, such as drill-and-blast tests, characterization of the excavation damaged zone（EDZ）, and long-term deformation monitoring of surrounding rocks, have been performed in the BET. The methodologies and technologies established in the BET will serve for URL construction.According to the achievements of the characterization of the URL site, a preliminary design of the URL with a maximum depth of 560 m is proposed and necessary in situ tests in the URL are planned.

The ORR electron transfer kinetics control via Co-N_(x) and graphitic N sites in cobalt single atom catalysts in alkaline and acidic media

Cost-effective 3d transition metal(TM) based single atom catalysts(SACs) for oxygen reduction reaction(ORR) are potential alternatives for Pt-based electrocatalysts in fuel cells and metal-air batteries.Understanding the effects of SACs’ properties and active site composition on the catalytic performance is significant to construct highly efficient catalysts. Here, we successfully promote the activity of cobalt single atoms decorated on N-doped carbon nanosheets via tuning the content of different nitrogen components, which outperforms most reported cobalt SACs. The activity and kinetics show positive correlation trends with the content of Co-Nxand graphitic N, serving as the main active sites.Furthermore, ORR kinetics in alkaline media can be positively affected by the conductivity of catalysts while no similar relation is observed in acidic media. The slight loss of Co-Nxsites engenders a mild change of performance in alkaline media, while the decrease of Co-Nxsite activity due to chemical oxidation of carbon support and the loss of Co-Nxsites in acidic media exacerbate the degradation of performance. Our work provides an insight into the relation between ORR electron transfer kinetics and active sites in 3d TM based SACs.

Nuclephilic ring opening of epoxides promoted by multi-site phase-transfer catalyst:An efficient and eco-friendly route to synthesis of β-hydroxythiocyanate

A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multi- site phase-transfer catalyst, α,α＇,α＂-N-hexakis（triethylammoniummethylene chloride）-melamine, is developed. A variety of ^-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 2009 Ali Reza Kiasat. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Transition Dipole, Charge Transfer, and Electron-hole Coherence in Two-photon Absorption： Visualizations with Two Dimensional Site and Three Dimensional Cube Representations

The developed visualization methods of two dimensional （2D） site and three dimensional （3D） cube representations have been performed to show the orientation of transition dipole, charge transfer, and electron-hole coherence in two-photon absorption （TPA）. The 3D cube representations of transition density can reveal visually the orientation and strength of transition dipole moment, and charge different density show the orientation of charge transfer in TPA. The 2D site representation can reveal visually the electron-hole coherence in TPA. The combination of 2D site and 3D cube representations provide clearly inspect into the charge transfer process and the contribution of excited molecular segments for TPA.

Activating coordinative conjugated polymer via interfacial electron transfer for efficient CO_(2) electroreduction

With tunable local electronic environment,high mass density of MN4sites,and ease of preparation,metal-organic conjugated coordinative polymer(CCP) with inherent electronic conductivity provides a promising alternative to the well-known M-N-C electrocatalysts.Herein,the coordination reaction between Cu^(2+)and 1,2,4,5-tetraaminobenzene(TAB) was conducted on the surface of metallic Cu nanowires,forming a thin layer of CuN4-based CCP(Cu-TAB) on the Cu nanowire.More importantly,interfacial transfer of electrons from Cu core to the CuN4-based CCP nanoshell was observed within the resulting CuTAB@Cu,which was found to enrich the local electronic density of the CuN4sites.As such,the CuTAB@Cu demonstrates much improved affinity to the*COOH intermediate formed from the rate determining step;the energy barrier for C-C coupling,which is critical to convert CO_(2)into C2products,is also decreased.Accordingly,it delivers a current density of-9.1 mA cm^(-2)at a potential as high as 0.558 V(vs.RHE) in H-type cell and a Faraday efficiency of 46.4% for ethanol.This work emphasizes the profound role of interfacial interaction in tuning the local electronic structure and activating the CuN4-based CCPs for efficient electroreduction of CO_(2).

New Kinetic Computerized Model for Multicomponent Mass Transfer in Bi-Functional Matrix of NanoComposites

The aim of this theoretical investigation is the description of the multicomponent mass transfer process in the Nano- Composites (NC)—novel materials with the bi-functional matrix. The new theoretical NC Model is assigned for the modern theoretical investigations of the multicomponent mass transfer kinetics in the bi-functional NC materials. This NC Model for the multicomponent mass transfer in the bi-functional NC matrix includes into the consideration the proposed key conception—two co-existing routes: I—chemical reactions onto the active NC centers-sites, and II—diffusion mass transfer inside the bi-functional NC matrix. All the results are presented in the terms of the additional key concept: propagating multicomponent concentration waves (W+) in the NC matrix. The used W+ concept for the description of the multicomponent NC mass transfer kinetics give the clear interpretation of the computerized results. The mass transfer process in the NC matrix has been described theoretically by computerized simulation. The results of the calculations are new and illustrated by author’s animations showing visually the propagation of the multicomponent concentration waves (W) inside the various NC matrixes: r-beads, cylindrical ro-fibers, or planar L-membranes. Two variants of modeling for mass transfer diffusion kinetics in the bi-functional NC matrixes with one (Variant 1), or two (Variant 2) dissociation-association reactions at the active nano-sites (R0) are considered theoretically.

Co掺杂Mn_(2)O_(3)复合材料的构筑及活化过氧单硫酸盐降解医药废水

废水中的抗生素对人类健康与生态安全构成了重大威胁,通过活化过氧单硫酸盐(PMS)产生活性氧物种是处理抗生素废水的有效手段。然而,由于电子迁移效率不足,实现高效的PMS活化仍然具有挑战性。在此,Co掺杂的Mn_(2)O_(3)催化剂(Co5-Mn_(2)O_(3))通过简单的一步煅烧法得到,以氧氟沙星(OFX)为目标污染物,考察了Co5-Mn_(2)O_(3)/PMS体系的降解性能,在15 min内OFX去除率达到了95%,相比于原始Mn_(2)O_(3)提升了12.3倍,同时Co5-Mn_(2)O_(3)/PMS体系对多种污染物(环丙沙星、磺胺甲恶唑、四环素、罗丹明B和甲基橙)均表现出良好的降解性能,体现了实际应用的潜力。X射线光电子能谱证实,Co掺杂引起了催化剂表面重构与电子迁移实现了Mn^(4+)-O-Co^(2+)活性位点的形成。猝灭实验分析,富电子Co位点与缺电子的Mn位点可以有效地活化PMS生成硫酸根自由基与单线态氧从而实现OFX的高效去除。这项工作为控制催化功能提供了一种活性位点的结构调控方法,为自由基与非自由基耦合降解提供新视角。

一种基于标准样品浓度稀释的在线氚监测仪校准装置

为解决在线氚监测仪的现场校准问题,开展了在线氚监测仪现场校准方法研究,主要包括现场校准装置的机械构造、工作原理、校准装置量值的确定,以及需要开展的校准项目。利用该现场校准装置和氚活度浓度标准装置,对同一台在线氚监测仪进行了校准比较,结果表明两者的校准因子分别为1.07和1.05,相对偏差约为2%,该现场校准装置具备量值传递的能力,可满足现场校准要求。此外,该校准装置具有便携性、可操作性和可拆分的特点,可保证现场校准不受场所作业空间的限制,适合在现场进行校准实验,可解决国内在线氚监测仪设备无法溯源的问题。

基于净能力及二阶锥规划的分布式光储多场景协同优化策略

针对现有配电网中分布式光储调度模型存在资源协同不足、求解复杂等问题,提出了一种基于净能力及二阶锥规划的分布式光储多场景协同优化调度策略。通过引入储能接入配电网后的功率转移分布因子,提出一种基于系统净能力的储能最优选址计算方法;综合考虑储能的运行特性和分布式光伏的出力不确定性,建立以系统日综合成本和削峰填谷为目标的分布式光储多场景协同优化调度模型;利用二阶锥松弛和Big-M法对潮流约束、储能运行约束进行处理,将原规划模型转化为混合整数二阶锥规划问题。以IEEE 33节点系统和西北某实际系统为算例进行仿真分析,结果表明所提方法能在降低负荷峰谷差和日综合成本、平抑负荷波动的同时,显著提高对分布式光伏的消纳能力,验证了所提方法的有效性和可行性。

电控离子选择渗透技术盐湖提锂传质模型

电控离子选择渗透(ESIP)是一种新型离子分离技术,可实现在复杂盐溶液中连续高选择性提取痕量目标离子。本工作研究了外加电场和电活性位点耦合作用下锂离子(Li+)在ESIP膜内的传质行为,引入电活性位点浓度参数对离子在膜相中的电化学势进行修正,提出修正的Donnan模型,结合电解质溶液电中性假设、界面电化学势守恒和法拉第定律,以Nernst–Planck方程为理论基础,建立了一维ESIP锂离子传质模型。重点研究了外加电场、接收液浓度、膜内电活性位点浓度以及膜厚4种参数对Li+在ESIP膜内传质过程的影响,为ESIP分离技术的生产放大提供依据。

二级垃圾回收中转设施选址问题的降阶回溯算法

随着我国城市化进程的加快和经济的高速发展,城市中因生产生活所产生的垃圾废料量日益增加,如何有效地建立回收中转设施是当前社会需要解决的问题。对二级垃圾回收设施选址问题进行研究,其实质为组合优化中的NP-hard问题。首先根据实际情况对二级垃圾回收中转设施选址问题进行数学建模,研究该问题的数学性质并给予证明,利用这些性质减小问题规模,降低求解难度;然后设计符合该问题的分配子算法、上下界子算法,基于以上算法提出一种可以在减小问题规模的同时得到精确解的降阶回溯算法;最后通过分析和模拟若干个示例进一步阐述该算法的原理及执行过程,结果表明该算法能通过减小问题规模,降低问题求解的难度。

乙烯在催化裂解催化剂上的低聚反应

以Y和ZSM-5分子筛催化裂解催化剂为研究对象,采用N_(2)吸附-脱附、氨气程序升温脱附(NH_(3)-TPD)和吡啶吸附红外(Py-FTIR)对其进行表征,研究了反应温度和反应压力对其催化乙烯低聚反应性能的影响。结果表明:催化裂解催化剂富含3~4 nm介孔,以弱L酸中心为主;在500~550℃和常压条件下,乙烯不易于转化,主要经低聚、裂化反应生成C_(3)~C_(4)烯烃,且丙烯的选择性高于丁烯;当反应温度高于550℃时,丙烯和丁烯的环化脱氢反应使焦炭的选择性大幅增加;与常压条件相比,在0.5~1.0 MPa反应压力下,乙烯在催化裂解催化剂上低聚反应的转化率明显升高;提高反应压力有利于C_(3)~C_(4)烯烃的氢转移反应,丙烷和丁烷的选择性升高,而焦炭的选择性降低。

铅冶炼场地粉尘重(类)金属的迁移转化

粉尘是铅冶炼场地土壤重(类)金属的来源之一,但粉尘中重(类)金属的迁移转化机制尚不明确。本文系统研究了此过程中重(类)金属的地球化学行为和解离机制。实验结果表明,两类粉尘样品中Pb、Zn、Cd和As的总量和浸出均超过标准,其中,两类粉尘中约有80%的Pb、Zn为生物可利用态,底吹炉粉尘中70%以上的As为弱酸提取态,而还原烟化炉粉尘弱酸提取态的重金属为Cd,占比为60%。Pb同位素结果显示,表土中97.12%的Pb来自冶炼过程中排放的粉尘。XRD和MLA结果表明,粉尘中的主要矿物为PbSO_(4)、ZnSO_(4)和CdSO_(4),表土中的矿物主要是石英、方解石、白云石和白云母。利用地球化学模型对主要矿物进行拟合发现,在酸性条件下,Pb、Zn和Cd的解离主要依赖于硫酸盐矿物,而As的解离与氢氧化铁的吸附作用有关。

民主正当性视野下的检察官统一调用制度

在民主正当化链条理论的视野中,检察官统一调用制度具有鲜明的功能取向,其与“检察一体”原则的关联指向保证检察权的统一有效行使,因此可获得宪法功能与制度层面的正当性。在保证个案关联度的前提下,检察官统一调用并不构成实质上的任命,被调用检察人员的人事正当化链条保持存续,同时,地方人大及其常委会的地方性不能否定检察权及其分配的统一性和法定性,检察官由此可以跨院履职。但是,检察官统一调用对调出地与调入地检察机关的工作均可能产生影响,并由此影响两地检察机关与人大常委会的责任链条,因而调用一般需要获得两地检察机关及同级人大常委会的同意,避免民主问责的落空。通过遵循一定的调用条件,检察官统一调用将不会影响原有民主正当化水平。

基于分裂注意力机制的DNA转录因子结合位点预测

准确识别DNA序列中的转录因子结合位点对于基因表达解析和药物设计等具有重要意义。基于深度学习的各种预测方法已被应用于转录因子结合位点任务中,但预测性能尚有提升空间。为此,提出一种新的深度学习方法ResNest-TFBS,用于预测690个ChIP-seq数据集上的转录因子结合位点。该方法首先在序列One-hot编码的基础上通过引入DNA的分子动力学特征与静电势能特征提取DNA的空间结构特性;其次利用分裂注意力机制与残差结构组成ResNest模型进行训练,从而将通道注意力机制应用于不同通道分支,以捕获其在全局数据集上学习到的特征间交互与多通道表示;最后将上述先验知识迁移至690个ChIP-seq数据集上,并进行广泛测试。实验结果表明,ResNest-TFBS性能优异,平均AUC为0.929。此外,通过SHAP工具验证不同特征在该任务中的贡献程度,证实所引入的特征为转录因子结合位点预测提供了更具价值的生物学线索。

基于NSGAⅡ算法的垃圾中转站选址及垃圾收运研究

随着垃圾分类政策的实施,垃圾中转站的数量缺少,亟需新建。垃圾分类不仅要在源头上受到重视,在垃圾收运过程中也需要重视。垃圾中转站选址不仅需要考虑成本问题,还需要考虑对环境产生的负效应,构建了以建设数量最小化、成本最小化、环境负效应最小化的多目标规划模型,用NSGA-Ⅱ算法(带精英策略的非支配排序遗传算法(Elitist Non-Dominated Sorting Genetic Algorithm))对模型进行求解。案例部分选取了上海市嘉定区垃圾中转站的选址,验证了模型的有效性。

High-level radioactive waste disposal in China: update 2010

For geological disposal of high-level radioactive waste （HLW）, the Chinese policy is that the spent nuclear fuel （SNF） should be reprocessed first, followed by vitrification and final disposal. The preliminary repository concept is a shaft-tunnel model, located in saturated zones in granite, while the final waste form for disposal is vitrified high-level radioactive waste. In 2006, the government published a long-term research and development （R＆D） plan for geological disposal of high-level radioactive waste. The program consists of three steps： （1） laboratory studies and site selection for a HLW repository （2006-2020）; （2） underground in-situ tests （2021-2040）; and （3） repository construction （2041-2050） followed by operation. With the support of China Atomic Energy Authority, comprehensive studies are underway and some progresses are made. The site characterization, including deep borehole drilling, has been performed at the most potential Beishan site in Gansu Province, Northwestern China. The data from geological and hydrogeological investigations, in-situ stress and permeability measurements of rock mass are presented in this paper. Engineered barrier studies are concentrated on the Gaomiaozi bentonite. A mock-up facility, which is used to study the thermo-hydro-mechano-chemical （THMC） properties of the bentonite, is under construction. Several projects on mechanical properties of Beishan granite are also underway. The key scientific challenges faced with HLW disposal are also discussed.

Simulation of multi-support depth-varying earthquake ground motions within heterogeneous onshore and offshore sites

This paper presents a novel approach to model and simulate the multi-support depth-varying seismic motions（MDSMs） within heterogeneous offshore and onshore sites.Based on 1 D wave propagation theory,the three-dimensional ground motion transfer functions on the surface or within an offshore or onshore site are derived by considering the effects of seawater and porous soils on the propagation of seismic P waves.Moreover,the depth-varying and spatial variation properties of seismic ground motions are considered in the ground motion simulation.Using the obtained transfer functions at any locations within a site,the offshore or onshore depth-varying seismic motions are stochastically simulated based on the spectral representation method（SRM）.The traditional approaches for simulating spatially varying ground motions are improved and extended to generate MDSMs within multiple offshore and onshore sites.The simulation results show that the PSD functions and coherency losses of the generated MDSMs are compatible with respective target values,which fully validates the effectiveness of the proposed simulation method.The synthesized MDSMs can provide strong support for the precise seismic response prediction and performance-based design of both offshore and onshore large-span engineering structures.