Tuning electronic structure of RuO_(2)by single atom Zn and oxygen vacancies to boost oxygen evolution reaction in acidic medium

The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but challenging.Herein,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation.Simultaneously,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction barrier.As a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.

磷掺杂碳负载Zn_(x)P_(y)O_(z)常温常压下高效电催化合成氨

合成氨(NH_(3))的发展是现代工业进程和人类生存的基石。受氮气(N_(2))化学惰性的限制,当前的合成氨工业能源消耗高并且排放大量的二氧化碳。电化学氮气还原反应(NRR),是有望取代高能耗的Haber-Bosch(HB)合成法的一种绿色可持续的合成氨工艺。然而,因氮气以及析氢竞争富反应(HER)导致电催化氮气还原极低的NH_(3)产率和能量转换效率一直是目前人工固氮领域面临的挑战。在本文中,我们报道了一种具有丰富孔结构的磷掺杂碳(PC)负载Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)纳米复合材料(h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)),在酸性和中性介质中将N_(2)高效催化转化为NH_(3)。其独特的分级多孔结构提高了表面粗糙度并加快了氮气在催化剂体相中的扩散,这有利于延长氮气在催化剂表面的停留时间以及提高活性位点的利用效率。而多组分的均匀分布可以调节电子结构并优化反应中间体的吸附行为,进而提高活性位点的本征活性。在0.1mol·L^(-1)HCI电解液中,h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)在-0.2 V vs.可逆氢电极(RHE)电位下NH_(3)的产率可以达到38.7±1.2μg·h^(-1)·mgcat^(-1),法拉第效率为19.8%±0.9%。此外;h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)在0.1 mol·L^(-1)Na_(2)SO_(4)溶液中同样展现出优异的电催化氮气还原合成氨性能,NH_(3)产率及法拉第效率分别为17.1±0.8μg·h^(-1)·mgcat^(-1)和15.g%±0.6%,明显优于PC/Zn_(3)P_(2)、C/ZnO和大多数报道的非贵金属电催化剂。这种优异的性能主要归因于多孔结构有利于传质及多组分活性位点协同效应。此外,我们采用非原位X射线光电子能谱(XPS)、透射电子显微镜(TEM)和X射线衍射(XRD)等表征手段对NRR测试前后h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)的组成和结构变化进行了剖析。在反应后检测到了新增的N物种信号,证明催化剂确实发生了氮气还原反应。本研究提供了一种通过同步构建传质通道并耦合不同的活性位点以协同增强NRR活性和选择性的新思路,这对加快绿色制氨工业化具有重大意义。

Electron-deficient ZnO induced by heterointerface engineering as the dominant active component to boost CO_(2)-to-formate conversion

Electrocatalytic CO_(2)-to-formate conversion is considered an economically viable process.In general,Zn-based nanomaterials are well-known to be highly efficient electrocatalysts for the conversion of CO_(2) to CO,but seldom do they exhibit excellent selectivity toward formate.In this article,we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency(FE)of 86%at−0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO_(2) to formate than pristine ZnO and ZnSnO3.In particular,the FEs of the C1 products(CO+HCOO−)exceed 98%over the potential window.The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d-band center,which results in moderate Zn-O hybridization of HCOO*and weakened Zn-C hybridization of competing COOH*,thus greatly boosting the HCOOH generation.Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO_(2) reduction.

通信电源系统智能浪涌保护模块的设计与防护特性

通信电源系统面临着严酷的暂态过电压应力,传统过电压保护器难以兼顾雷电过电压保护水平与长期运行可靠性,其防护失效的问题严重影响通信基站运行的安全可靠性。文中提出了一种由限压型压敏电阻与短路型可控开关组成的智能可控浪涌保护模块的设计理念,通过对直流参考电压、可控比等参数的理论分析与自动能量耦合触发电路的实验研究,研制出了智能过电压防护模块样机,并进行了性能验证实验。浪涌保护模块直流参考电压为2.16 kV,在380 V额定工频电压下运行,其工作的荷电率很低,泄漏电流很小,在标幺值为2(基准值380V)的工频过电压下依然能保持长期的可靠稳定运行。在10 kA范围内(标准8/20雷电流),浪涌保护模块的冲击残压最大值为1.5 kV,冲击残压与直流参考电压之间的压比约为0.7,远小于常规限压型过电压保护器约1.5的压比。智能浪涌保护模块的过电压保护水平得到了显著的提升,为通信基站的稳定、安全运行提供了有力的保障。

Analysis on Change Trend and Influencing Factors of Natural Resource Utilization of Community Farmers around the Habitat of Giant Pandas

The habitat of giant pandas borders the living areas of farmers in surrounding communities. Due to the low level of economic development and resource used method, the life of community farmers depends on the natural resources of the habitat of giant pandas. Analyzing the natural resource utilization of farmers in communities around the habitat of giant pandas is conducive to formulating more reasonable management policies and protecting the habitat of giant pandas more effectively. Based on the field survey data, this paper classifies the main ways of community farmers using the natural resources of the habitat of giant pandas, counts the quantity of resources used and analyzes their change trends. On this basis, this paper selects indicators, constructs a model and analyzes the main influencing factors affecting the natural resources utilization of community farmers from three aspects: the individual characteristics of household heads, the family characteristics of community farmers and the residence characteristics of community farmers.

基于ANSYS的桌面数控车床静刚度分析及结构优化

为了适应社会的需求,桌面数控车床逐渐进入人们的视野当中,由于其轻便、高效、低成本、占用资源少等特点,被人们广泛关注。但尺寸小带来的问题是刚性不好,从而导致加工精度较低。对自主设计的Ⅰ型桌面数控车床采用有限元法在考虑接合面刚度下进行建模以及静刚度仿真分析,分别得到了桌面车床在X、Y、Z方向上的变形数据,并根据仿真结果对其结构提出了一些优化建议,最后设计出质量轻、刚性好的Ⅱ型桌面数控车床,经数据结果对比,整体上质量减轻了5.1%,X、Y、Z方向上静刚度分别提高了19.47%、24.97%和12.12%,验证了所进行结构优化的合理性。

Gallbladder sarcomatoid carcinoma:Seven case reports

BACKGROUND Gallbladder sarcomatoid carcinoma is a rare and aggressive tumor,and little is known about its clinical behavior,prognosis,and optimal treatment.CASE SUMMARY From 1997 to 2017,we collected seven cases of gallbladder sarcomatoid carcinoma at our institution.The median patient age was 68.5 years.Six(85.7%)patients were female.Overall,85.7%(6/7)of the tumors had a maximal diameter greater than 7 cm.Late TNM stage was associated with a significantly poor prognosis.All patients with advanced-stage(III/IV)disease died from metastases or disease progression shortly after surgery.One patient with stage IIIB disease who received adjuvant chemoradiotherapy(gemcitabine and capecitabine)achieved a progression-free survival(PFS)of 12 mo and overall survival of 15 mo,which might be the longest PFS reported among patients who ultimately experienced recurrence or metastasis.CONCLUSION Sarcomatoid carcinoma is a unique and aggressive gallbladder malignancy.Surgery is suggested as the first and only recognized treatment.There is a significant difference in prognosis between patients with early-stage and advanced-stage disease.Postoperative adjuvant therapy may bring survival benefits for locally advanced patients.Gemcitabine combined with fluorouracil and radiotherapy could be a potential strategy.

基于“任务驱动”的高校学前教育专业课程在线教学设计与实践——以《学前儿童科学教育》为例

"任务驱动"是一种以情境任务为起点,以解决问题、完成任务为驱动力,以学生自主探究、教师导学为手段,以培养学生的专业素养和创新能力为目的的教学模式。基于"任务驱动"的在线教学充分实现了线上有资源,线下有活动,过程有评估,破解了课程教学的现实桎梏,构筑了智能教育新形态。文章以"学前儿童科学教育"课程为例,构建了基于"任务驱动"的在线教学设计,并进行了实践性反思,以期为高校学前教育专业科学领域的课程建设提供借鉴与参考。

Analytical expression for betatron tune shift due to field errors in lump quadrupole

The integrated gradient of a quadrupole will be deviated by a close neighboring sextupole, and this is called the effect of fringe field interference. Using the Lie algebra techniques, an analytical expression for the betatron tune shift due to this effect has been derived. The process does not depend on the supposition of the thin-lens quadrupoles. It can be used to estimate the tune shift differences between the designed lattice and the one including the fringe field interference. More generally, the method can be applied to other kinds of fringe field interference.

Study of family environmental factor on only-children’s personality

Objective: To analyze the impact of family environment on only-children’s personality. Methods: Using cross-sectional design to recruit only-children aged 6 - 16 years old;using EPQ to evaluate the children’s personality. The general questionnaire, PSDQ (Parenting Styles and Dimensions Questionnaire), FAD-GFS (The General Functioning Scale of MacMaster family activity device), SLE(Stressful Life Events), FSQ (Family Stresses Questionnaire), FLQ (Family Life Questionnaire), EFQ (Everyday Feelings Questionnaire) were used to collect information about family environment from parents. Results: In only-child family, standardized regression equations of family environment influence on children personality include: 1) EPQ-p = 0.087 × SLE + 0.207 × father autocratic parenting + 0.131 × education of father + 0.110 × family type - 0.110 × role of discipline - 0.080 × parental attitude + 0.087 × family adaptability;2) EPQ-e = 0.105 × EFQ- 0.088 × SLE - 0.101 × family income;3) EPQ-n = 0.143 × SLE - 0.090 × family cohesion + 0.089 × family income + 0.117 × the orderly’s attitude - 0.138 × the child’s role experience of FLQ - 0.101 × parents shaping the behavior of children of FLQ and 4) EPQ - l = -0.136× SLE - 0.093 × relationship between parents - 0.155 × attitude of the old. Conclusion: It is important for children to develop personality normally if the father doesn’t choose autocratic parent style. Children tend to be optimistic if the parent can feel happy. The stressful life events are a double-blade sword depending on the parent’s handling. The difference of the parenting style can influence the lie-personality of children.

On the Multiscale Oceanic Heat Transports Toward the Bases of the Antarctic Ice Shelves

The mass balance of the Antarctic Ice Sheet(AIS)is important to global sea-level change.The AIS loses mass mainly through basal melting and subsequent calving of the Antarctic ice shelves.However,the simulated basal melting rates are very uncertain in ice sheet models,partially resulting from the poor understanding of oceanic heat transports.In this article,we review the recent progress in understanding and simulating such heat transports.Regulated by major circulation features,Circumpolar Deep Water(CDW)is much closer to the Bellingshausen-Amundsen Seas and the Cooperation Sea(60°E to 90°E)and the sector further east to 160°E.The ice shelves within these sectors are experiencing enhanced basal melting resulting from tropical forcing and intensified westerlies.Around West Antarctica,the isopycnal structure favors the delivery of CDW across slopes and shelves,while around East Antarctica,the persistent and strong westward Antarctic Slope Current(Front)acts to prevent warm-water intrusion.Both eddies and troughs favor heat transport to the fronts of the ice shelves and even into the cavities.The sharp contrast between the water column thicknesses on both sides of ice shelf fronts blocks the barotropic inflows and can excite topographic Rossby waves.Inside the cavities,the heat fluxes to the bases of the ice shelves are controlled by the cavity geometry,the circulations in the cavities,and the properties of the water masses beneath the ice shelves.Limited direct observations of cavities have promoted the development of various models.To improve basal melting simulations,meltwater plume models have been developed to study meltwater-laden mixed layer dynamics by increasing the vertical resolution,with recent advanced studies considering the vertical structures of frazil ice concentration and velocity.To reduce the uncertainties in the simulated and projected basal mass loss of the Antarctic ice shelves,future efforts should be devoted to improving the bathymetry and cavity geometry,investigating small-scale processes and parameterizing these processes in coupled climate-ice sheet models,and quantifying the feedback from the mass loss of the AIS.

晶格应变和异质界面工程协同促进铋基催化剂高效电催化CO_(2)还原生成甲酸

表面应力耦合异质结构是一种改善非均相催化剂催化性能的有效策略.它可以在调控催化剂电子结构的同时,促进电荷传输.一般来说,Bi基催化剂对CO_(2)电还原为甲酸的选择性高于ZnO,但是金属Bi的价格高于Zn.本文以十六烷基三甲基溴化铵为模板剂,通过一步水热法合成了一种具有多孔纳米片形貌的Bi_(2)O_(2)CO_(3)/ZnO异质结催化剂,用于高效电催化CO_(2)还原制备甲酸.在-1.0 V vs.RHE下,该催化剂展现出最大甲酸盐法拉第效率(92%),且在施加-1.2 V vs.RHE电压下甲酸盐偏电流密度为200 m A mg_(Bi)^(-1).更重要的是,对Bi的质量进行归一化发现,Bi_(2)O_(2)CO_(3)/ZnO的质量活度比纯Bi_(2)O_(2)CO_(3)的质量活度提升了3.1倍.通过X-射线光电子能谱和X-射线吸收谱测试表明,在该催化剂中,界面Zn原子电荷向Bi原子转移,形成了富电子的Bi_(2)O_(2)CO_(3)表面,有利于CO_(2)的捕获和活化;而异质结构引起的压缩应力有利于优化反应中间体的吸附能,二者协同提高了Bi_(2)O_(2)CO_(3)/ZnO电催化CO_(2)还原生成甲酸的选择性和活性.

问询函会影响企业实际税率吗——来自中国上市公司的证据

近年来非行政处罚性监管越来越成为维护资本市场稳定的重要手段,据此本文以证券交易所出具的问询函为研究对象,收集2014—2019年中国A股上市公司数据,检验企业收到问询函对实际税率的影响。研究发现,收到问询函后,上市公司实际税率有所提高,当问询函涉及税务问题且涉及的税务问题数量越多时,其对实际税率的提高作用越强;这一作用主要通过降低企业的代理成本来实现。进一步的研究发现,问询函对企业实际税率的影响因产权性质、政治关联、当地税务机关执法力度的差异而有所不同;相较于国有企业、政治关联企业以及当地税务执法力度较强的企业,问询函对实际税率的提高在民营企业、无政治关联企业、执法力度更弱的企业中更显著。本文的研究结果表明,问询函对企业实际税率具有监管作用,可以作为监管上市公司、维护市场稳定的手段。本文不仅丰富了新近关于问询函的研究,也对相关机构监管手段的创新有重要启示。

Modification and optimization of the storage ring lattice of the High Energy Photon Source

Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically finished.During the subsequent hardware and engineering design of the HEPS storage ring based on the PDR design,a few problems and challenges emerged,calling for modifications of the lattice.Method In this paper,we will introduce the background and reasons for the modifications and present the linear optics and simulation results for the nonlinear performance of the modified lattice of the HEPS storage ring.Result and conclusion The modified lattice satisfies the requirements from hardware and engineering design.

Three-dimensional hierarchical Co(OH)F nanosheet arrays decorated by single-atom Ru for boosting oxygen evolution reaction

Electronic coupling with the support plays a crucial role in boosting the intrinsic catalytic activity of a single-atom catalyst.Herein,the three-dimensional(3D)hierarchical Co(OH)F nanosheet arrays modified by singleatom Ru(SA-Ru/Co(OH)F)are prepared by a facile one-step hydrothermal method under mild conditions,which exhibit excellent activity with an overpotential of 200 and 326 mV at 10 and 500 mA cm^(−2),respectively,as well as robust stability for oxygen evolution reaction(OER)in 1.0 mol L^(−1)KOH electrolyte.The study of electronic structures and surface chemical states before and after OER testing reveals that the strong electronic coupling between single-atom Ru and Co(OH)F induces the charge redistribution in SA-Ru/Co(OH)F and suppresses the excessive oxidation of Ru into higher valence state(more than+4)under high OER potential.This work provides a strategy to stabilize single-atom Ru by Co(OH)F that can enhance the activity and durability for OER under large current densities.

A simple,rapid,and practical method for single-cell proteomics based on mass-adaptive coating of synthetic peptides

Since a typical mammalian cell contains only 200–300 picograms of proteins and the lack of a proteome amplification strategy[1],a practical and high-throughput approach for single-cell proteomics has long been awaited.A series of methods have been explored to make single-cell proteomics available.The design of nanoPOTS and OAD chip-based processes minimizes sample preparation steps and volumes to reduce sample loss[2,3].

CXCL13 expression in mouse 4T1 breast cancer microenvironment elicits antitumor immune response by regulating immune cell infiltration

Breast cancer is the most commonly diagnosed cancer type and the leading cause of cancer-related deaths among women worldwide.Previous studies have reported contradictory performance of chemokine CXC motif ligand 13(CXCL13)in breast cancer.In this study,The Cancer Genome Atlas database analysis revealed that CXCL13 was overexpressed in various human cancers including breast carcinoma,and associated with good clinical prognosis in breast cancer.Flow cytometry detection also found upregulated intracellular CXCL13 expression in human breast cancer cell lines.To explore the possible role of CXCL13 in the breast cancer microenvironment,mouse triple negative breast cancer(TNBC)was lentivirally transfected to stably overexpress mouse CXCL13(4T1-CXCL13).Both parental 4T1 and 4T1-CXCL13 strains showed no in vitro or in vivo endogenous cell surface CXCR5 expression.In immune-competent BALB/c mice,the in vivo tumor growth of 4T1-CXCL13 was significantly inhibited and even completely eradicated,accompanied with increased infiltrations of CD4^(+),CD8^(+)T lymphocytes and CD11b^(+)CD11c^(+)DCs.Further investigations showed that CXCL13 expression in the 4T1 tumor microenvironment elicited long-term antitumor immune memory,and rejection of distal parental tumor.The antitumor activity of CXCL13 was remarkedly impaired in BALB/cA-nu nude mice,or in BALB/c mice with CD8^(+)T lymphocyte or NK cell depletion.Our investigation indicated that CXCL13 expression in TNBC triggered effective antitumor immunity by chemoattracting immune cell infiltrations and could be considered as a novel prognostic marker for TNBC.

Praseodymium iridium oxide as a competitive electrocatalyst for oxygen evolution reaction in acid media

Amorphous iridium oxides(IrO_(x))are highly active for oxygen evolution reaction(OER)in acid media;however,it is generally unstable compared with commercial IrO_(2).Recently,many non-noble metal-iridium mixed oxides are prepared for catalyzing OER efficiently.Herein,we report a cubic fluorite-type praseodymium iridium oxide with the surface of IrO_(x)(IrO_(x)/Pr_(3)IrO_(7))that shows the improved activity and stability in 0.1 mol L^(-1) HClO_(4) solution,characterized by an overpotential of 305 mV at the benchmark of 10 mA cm^(-2) and a small Tafel slope of 37 mV dec^(-1),indicating a fast reaction kinetics and a competitive activity compared with the benchmark IrO_(2) and most reported electrocatalysts.The initial potential increases by less than 0.07 V after continuous OER testing over 60,000 s.In contrast,IrO_(2) becomes nearly inactive for the OER within 20,000 s.Density functional theory calculations uncover that the optimal energy level path follows lattice oxygen mechanism(LOM).This work enlarges the family of the IrO_(x)-type OER electrocatalyst in acid media.

Plasmon-enhanced broad-band quantum-cutting of NaBaPO4:Eu^2+,Er^3+phosphors with silver nano-particles

NaBaPO4:Eu^2+,Er^3+phosphors and Ag nano-particles(NPs)were prepared by the solid-state reaction and chemical reduction method,respectively.The fluorescence spectra and decay curves demonstrate the effective energy transfer from Eu^2+to Er^3+and the existence of three-photon quantum-cutting through two-step cross-relaxation of Er^3+.The quantum-cutting emission is peaked at 1534 nm with a broad excitation band centered at 352 nm,Plasmon-enhanced quantum-cutting of NaBaPO4:Eu^2+,Er^3+phosphors was realized by decorating Ag NPs.The largest enhancement factor is 1.395.It is hopeful to improve the photovoltaic conversion efficiency of Ge solar cells by using this phosphor.