Construction of a Cu@hollow TS-1 nanoreactor based on a hierarchical full-spectrum solar light utilization strategy for photothermal synergistic artificial photosynthesis

The artificial photosynthesis technology has been recognized as a promising solution for CO_(2) utilization.Photothermal catalysis has been proposed as a novel strategy to promote the efficiency of artificial photosynthesis by coupling both photochemistry and thermochemistry.However,strategies for maximizing the use of solar spectra with different frequencies in photothermal catalysis are urgently needed.Here,a hierarchical full-spectrum solar light utilization strategy is proposed.Based on this strategy,a Cu@hollow titanium silicalite-1 zeolite(TS-1)nanoreactor with spatially separated photo/thermal catalytic sites is designed to realize high-efficiency photothermal catalytic artificial photosynthesis.The space-time yield of alcohol products over the optimal catalyst reached 64.4μmol g−1 h−1,with the selectivity of CH3CH2OH of 69.5%.This rationally designed hierarchical utilization strategy for solar light can be summarized as follows:(1)high-energy ultraviolet light is utilized to drive the initial and difficult CO_(2) activation step on the TS-1 shell;(2)visible light can induce the localized surface plasmon resonance effect on plasmonic Cu to generate hot electrons for H2O dissociation and subsequent reaction steps;and(3)low-energy near-infrared light is converted into heat by the simulated greenhouse effect by cavities to accelerate the carrier dynamics.This work provides some scientific and experimental bases for research on novel,highly efficient photothermal catalysts for artificial photosynthesis.

Experiment and simulation on degradation and burnout mechanisms of SiC MOSFET under heavy ion irradiation

Experiments and simulation studies on 283 MeV I ion induced single event effects of silicon carbide(SiC) metal–oxide–semiconductor field-effect transistors(MOSFETs) were carried out. When the cumulative irradiation fluence of the SiC MOSFET reached 5×10^(6)ion·cm^(-2), the drain–gate channel current increased under 200 V drain voltage, the drain–gate channel current and the drain–source channel current increased under 350 V drain voltage. The device occurred single event burnout under 800 V drain voltage, resulting in a complete loss of breakdown voltage. Combined with emission microscope, scanning electron microscope and focused ion beam analysis, the device with increased drain–gate channel current and drain–source channel current was found to have drain–gate channel current leakage point and local source metal melt, and the device with single event burnout was found to have local melting of its gate, source, epitaxial layer and substrate. Combining with Monte Carlo simulation and TCAD electrothermal simulation, it was found that the initial area of single event burnout might occur at the source–gate corner or the substrate–epitaxial interface, electric field and current density both affected the lattice temperature peak. The excessive lattice temperature during the irradiation process appeared at the local source contact, which led to the drain–source channel damage. And the excessive electric field appeared in the gate oxide layer, resulting in drain–gate channel damage.

Accurate design of spatially separated double active site in Bi_(4)NbO_(8)Cl single crystal to promote Z-Scheme photocatalytic overall water splitting

The efficiency of photocatalytic overall water splitting was mainly limited by the slow reaction kinetics of water oxidation.How to design effective surface active site to overcome the slow water oxidation reaction was a major challenge.Here,we propose a strategy to accelerate surface water oxidation through the fabrication spatially separated double active sites.FeCoPi/Bi_(4)NbO_(8)Cl-OVs photocatalyst with spatially separated double active site was prepared by hydrogen reduction photoanode deposition method.Due to the high matching of the spatial loading positions of FeCoPi and OVs with the photogenerated charge distribution of Bi_(4)NbO_(8)Cl and corresponding reaction mechanisms of substrate,the FeCoPi and OVs on the(001)and(010)crystal planes of Bi_(4)NbO_(8)Cl photocatalyst provided surface active site for water oxidation reaction and electron shuttle reaction(Fe^(3+)/Fe^(2+)),respectively.Under visible light irradiation,the evolution O_(2)rate of FeCoPi/Bi_(4)NbO_(8)Cl OVs was 16.8μmol h^(-1),as 32.9 times as Bi_(4)NbO_(8)Cl.Furthermore,a hydrogen evolution co-catalyst PtRu@Cr_(2)O_(3)was prepared by sequential photodeposition method.Due to the introduction of Ru,the Schottky barrier between PbTiO_(3)and Pt was effectively reduced,which promoted the transfer of photogenerated electrons to PtRu@Cr_(2)O_(3)thermodynamically,the evolution H_(2)rate on PtRu@Cr_(2)O_(3)/PbTiO_(3)increased to 664.8 times.On based of the synchronous enhancement of the water oxidation performance on FeCoPi/Bi_(4)NbO_(8)Cl-OVs and water reduction performance on PtRu@Cr_(2)O_(3)/PbTiO_(3),a novel Z-Scheme photocatalytic overall water splitting system(FeCoPi/Bi_(4)NbO_(8)Cl-OVs)mediated by Fe^(3+)/Fe^(2+)had successfully constructed.Under visible light irradiation,the evolution rates of H_(2)and O_(2)were 2.5 and 1.3μmol h^(-1),respectively.This work can provide some reference for the design of active site and the controllable synthesis of OVs spatial position.On the other hand,the hydrogen evolution co catalyst(PtRu@Cr_(2)O_(3))and the co catalyst FeCoPi for oxygen evolution contributed to the construction of an overall water splitting system.

Loading CuO on the surface of MgO with low-coordination basic O^(2-)sites for effective enhanced CO_(2) capture and photothermal synergistic catalytic reduction of CO_(2) to ethanol

The higher capacity of CO_(2)adsorption on the surface of magnesium oxide(MgO)with low-coordination O^(2-)sites would effectively enhance the catalytic reduction of CO_(2).Herein,a series of copper oxide(CuO)and MgO composites with different mass ratios have been prepared by hydrothermal method and used for photothermal synergistic catalytic reduction of CO_(2)to ethanol.The catalyst with CuO mass ratio of 1.6% shows the best yield(15.17μmol·g^(-1)·h^(-1))under 3 h Xenon lamp illumination.The improved performance is attributable to the loose nano-sheet structure,uniform dispersion of active sites,the increased specific surface area,medium-strength basicity,the high separation efficiency of electrons and holes,and the formation of Mg-O-Cu species.The synthesized CuO and MgO composites with loose nano-sheet structure facilitate the diffusion of reactants CO_(2),so an excellent CO_(2)adsorption performance can be obtained.Meanwhile,the introduction of CuO in the form of bivalence provides higher specific surface area and porosity,thus obtaining more active sites.More importantly,the Mg-O-Cu species make the donation of electrons from MgO to CO_(2)easier,resulting in the breaking of the old Mg-O bond and the formation of C-O bond,thus promoting the adsorption and conversion of CO_(2)to ethanol.

Temperature dependence of single-event transients in SiGe heterojunction bipolar transistors for cryogenic applications

We experimentally demonstrate that the dominant mechanism of single-event transients in silicon-germanium heterojunction bipolar transistors(SiGe HBTs)can change with decreasing temperature from+20℃to-180℃.This is accomplished by using a new well-designed cryogenic experimental system suitable for a pulsed-laser platform.Firstly,when the temperature drops from+20℃to-140℃,the increased carrier mobility drives a slight increase in transient amplitude.However,as the temperature decreases further below-140℃,the carrier freeze-out brings about an inflection point,which means the transient amplitude will decrease at cryogenic temperatures.To better understand this result,we analytically calculate the ionization rates of various dopants at different temperatures based on Altermatt's new incomplete ionization model.The parasitic resistivities with temperature on the charge-collection pathway are extracted by a two-dimensional(2D)TCAD process simulation.In addition,we investigate the impact of temperature on the novel electron-injection process from emitter to base under different bias conditions.The increase of the emitter-base junction's barrier height at low temperatures could suppress this electron-injection phenomenon.We have also optimized the built-in voltage equations of a high current compact model(HICUM)by introducing the impact of incomplete ionization.The present results and methods could provide a new reference for effective evaluation of single-event effects in bipolar transistors and circuits at cryogenic temperatures,and could provide a new evidence of the potential of SiGe technology in applications in extreme cryogenic environments.

TiO2-incorporated polyelectrolyte composite membrane with transformable hydrophilicity/hydrophobicity for nanofiltration separation

The wettability of the membrane surface has shown obvious influent on the separation performance of the membrane.In this work,a hydrophilic PDA-[PDDA/TiO2]+Cl-membrane was prepared by a one-step codeposition of poly(diallyldimethylammonium chloride)(PDDA)polyelectrolyte solution containing positively charged TiO2@PDDA nanoparticles with the assistance of dopamine(DA).Such positively charged membrane can be transformed into a hydrophobic membrane PDA-[PDDA/TiO2]+PFO-via the counterion exchange between Cl-and PFO-(perfluorooctanoate).The transformation between hydrophilicity and hydrophobicity is reversible.For both hydrophilic and hydrophobic membranes,the nanofiltration performances were respectively investigated by the aqueous solution and ethanol solution of dyes including methyl blue(MB),Congo red(CR)and Evans blue(EB),and as well metal salt aqueous solution.The consecutive running stability and anti-fouling performance of both hydrophilic and hydrophobic membranes were explored.The results revealed that both membranes showed high nanofiltration performances for retention of dyes in(non)aqueous solution.For the hydrophilic membrane,the rejection of salts in a sequence is MgSO4>Na2SO4>MgCl2>NaCl.Moreover,both of the hydrophilic and hydrophobic membranes showed high stability and antifouling property.

新的社会阶层人士助力共同富裕的实践路径与政策建议

扎实推进共同富裕是新时代新征程党和国家的一项重大战略任务。新的社会阶层人士作为中国特色社会主义事业建设者,是助力共同富裕的一支重要力量。他们不断推动我国技术创新和产业技术进步,是有效提供公共服务、积极参与第三次分配的重要主体,其日常性的本职工作就是实现共同富裕进程的重要组成部分——以科技推动创新创业,实现高质量发展;积极参与第三次分配;促进公共服务均等化;等等。但新的社会阶层人士助力共同富裕面临共识不够、资金资源及政策支持不足、组织保障缺乏等问题。充分发挥新的社会阶层人士的积极作用,是统一战线工作的重要任务,新的社会阶层人士助力共同富裕,亟需统战部门探索有效路径,建议从四个方面着力:强化组织引领,不断增进共识;创新解决资金、资源、技术等难题;强化政策支撑;培育联谊组织,激发新的社会阶层人士的主体性。

Asymptotic solutions for the asymmetric flow in a channel with porous retractable walls under a transverse magnetic field

The self-similarity solutions of the Navier-Stokes equations are constructed for an incompressible laminar flow through a uniformly porous channel with retractable walls under a transverse magnetic field. The flow is driven by the expanding or contracting walls with different permeability. The velocities of the asymmetric flow at the upper and lower walls are different in not only the magnitude but also the direction. The asymptotic solutions are well constructed with the method of boundary layer correction in two cases with large Reynolds numbers, i.e., both walls of the channel are with suction, and one of the walls is with injection while the other one is with suction. For small Reynolds number cases, the double perturbation method is used to construct the asymptotic solution. All the asymptotic results are finally verified by numerical results.

基于随机森林模型内脏脂肪等级相关指标分析

目的探讨基于随机森林模型分析内脏脂肪等级的相关指标。方法本研究为横断面研究,选取2021年3—9月在黑龙江省医院健康管理中心进行体检的医院职工(包括在职职工和退休职工)共617例的各项实验室指标以及体成分分析各项指标,按照2∶1的比例将样本分为训练集(411例)和测试集(206例),模型共纳入预测变量110个,使用训练集数据进行随机森林模型构建,测试集数据进行模型验证,选择最优节点数和决策树数目,对构建模型的预测性能进行评价,同时选取重要性在前10位的相对重要因子进行下一步的研究。按内脏脂肪等级,对617名研究对象再次进行分组:内脏脂肪等级正常组和内脏脂肪等级偏高组,进一步分析前10位相对重要因子在组间的差异。结果随机森林模型的最优节点数为39、决策树数目为300。模型在测试集上的准确率为83.3%、精确率为73.9%、灵敏度为89.4%、特异度为78.7%,其受试者工作特征曲线下面积为0.881(95%CI:0.832~0.931)。模型中前10位相对重要因子依次为:体重指数、性别、年龄、尿酸、红细胞计数、单核细胞计数、C肽、癌胚抗原、糖化血红蛋白、谷氨酰转肽酶。内脏脂肪等级偏高组的体重指数、年龄、尿酸、红细胞计数、单核细胞计数、C肽、癌胚抗原、糖化血红蛋白、谷氨酰转肽酶水平均高于内脏脂肪等级正常组(均P<0.05);内脏脂肪等级偏高的发生率男性大于女性(P<0.05)。结论本研究构建的内脏脂肪等级的随机森林预测模型表现良好,内脏脂肪与机体肝功能、胰岛功能、免疫功能的改变均有关系。

百年统一战线认识和处理阶级阶层关系的基本经验

统一战线的根本问题是解决无产阶级解放运动的自身团结统一和同盟军问题。统一战线百年发展史,就是一部认识和处理阶级阶层关系的历史:阶级阶层关系是事关党的事业兴衰成败的战略问题,正确的阶级阶层分析是党正确认识与处理阶级阶层关系的前提,而政治上、理论上的成熟是正确进行阶级阶层分析的基础。当代中国,在经济快速发展、社会结构深刻变革、阶级阶层分化愈加明显的趋势下,如何客观地认识社会阶级阶层结构的变化及其利益关系变动所引发的社会矛盾,形成与之相匹配的工作体制、机制、力量,科学、恰当地协调阶级阶层关系,是执政党面临的极其重大的理论与现实问题。以史鉴今,全面总结和把握运用党的百年历史经验,对于新时代处理好阶级阶层关系、增进政治共识、壮大共同奋斗的磅礴力量,具有极大的借鉴意义。

纳米器件空间辐射效应机理和模拟试验技术研究进展

电子器件空间辐射效应是影响航天器在轨长期可靠运行的重要因素之一,一直是国际上抗辐射加固技术领域研究的热点和难点.高可靠、高集成度、高性能、低功耗、低成本是未来新一代先进电子系统发展的必然要求,采用更高性能的抗辐射加固纳米器件是必然的趋势.本文在深入调研国内外研究现状的基础上,分析了纳米器件辐射效应面临的新问题.纳米工艺存在着很多不同于大尺寸工艺的特点,沟道长度缩小到十几个纳米,栅氧化层等效厚度小于1 nm.在工艺上引入了纵向逆掺杂阱或横向晕环掺杂技术,以降低栅极诱导漏极漏电效应;在材料上引入了多元半导体材料、应变硅、锗硅、高k栅介质、金属栅极等,以降低器件功耗;在结构上引入了三维Fin FET结构,以增强栅的控制能力.这种趋于物理极限的工艺特点、新材料和新结构的采用产生了许多新的辐射效应现象和机制,模拟试验技术更加复杂,给抗辐射加固技术研究带来了新的挑战.本文综述了纳米器件辐射效应的研究现状和趋势,重点针对28 nm及以下特征工艺纳米器件辐射效应研究及模拟试验的需求,提出了需要研究的科学问题和关键技术,希望能为纳米器件抗辐射加固与空间应用提供参考.

Dissipative particle dynamics thermostat: a novel thermostat for molecular dynamics simulation of liquid crystals with Gay–Berne potential

The Gay–Berne(GB) model has been proved to be highly successful in the simulation of liquid crystal phases via both molecular dynamics(MD) and nonequilibrium molecular dynamics(NEMD). However, the conventional thermostats used in the simulations of GB systems, such as Nosé–Hoover and Langevin thermostats, have serious shortcomings especially in NEMD simulations. Recently, dissipative particle dynamics(DPD) has established itself as a useful thermostat for soft matter simulations, whereas the application of DPD thermostat in(NE)MD simulations is limited to the spherically isotropic potential models, such as the Lennard–Jones model. Considering the virtues of the DPD thermostat, that is, local, momentum conserved, and Galilean invariant, we extend the DPD thermostat to the non-spherical GB model. It is interesting to find that the translational DPD and rotational DPD thermostats can be used in the GB system independently and both can achieve the thermostatting effects. Also, we compared the performance of the DPD thermostat with other commonly used thermostats in NEMD simulations by investigating the streaming velocity profiles and the dynamics of phase separation in a typical but simple binary GB mixture under shear field. It is revealed that the known virtues of DPD thermostats, such as Galilean invariant, shear velocity profile-unbiased, and unscreened hydrodynamic interactions, are still intact when applying to GB systems. Finally, the appropriate parameters for the DPD thermostat in the GB system are identified for future investigations.

治理创新与新的社会阶层组织化建设

以党的十八届三中全会为标志,中国进入治理创新的新时代。而推进治理创新、实现国家治理体系与治理能力现代化,要求公共权力与多元主体建设基于共建共治共享之上的政治共同体与社会治理共同体。改革开放既是社会结构深刻变迁的过程,也是新的社会力量分化产生的过程。治理创新时代,新的社会阶层既是其最大增量,也是其最大变量。团结凝聚新的社会阶层,是治理创新迫切需要解决的问题。"组织起来"既是我们党的老传统,在新时代又被赋予新的使命,有其特定的内涵与功能。要做实做深新的社会阶层组织化,重在继续夯实"党委+群团+社会组织+自组织"多元协同的组织网络体系和工作格局。