First-Principles Insights into Pt_(n)/ZnO(0001)Catalyst:Regulation of Metal-Support Interaction through Surface Polarity

Polar surfaces are prevalent in metal oxides,the interactions between surface species with polar surfaces are different from those with non-polar surfaces,a thorough understanding of the interactions is key to regulate the performance of heterogeneous catalysts.In this work,we delve into the interaction of Pt_(n)(n=1-4)with polar ZnO(0001)-Zn and ZnO(0001)-O,and the influence of the surface polarity on the electronic structures and reactivity of Pt_(n)by using density functional theory calculations.The results suggest distinct differences in electronic structures of two exposed terminations,leading to different interactions with Pt_(n).The interaction between Pt_(n)and two terminations not only stabilizes the surface and clusters through polar compensation,but also induces opposite charges on the cluster at two terminations.Remarkably,the Pearson correlation coefficient reveals the interdependency between the electronic states of Pt_(n)and its performance in terms of small molecule adsorption/activation.These observations demonstrate the crucial role of surface polarity in regulating the electronic states and catalytic performance of active sites,and offer a possible design principle for supported catalysts.

Mechanism study on the influence of surface properties on the synthesis of dimethyl carbonate from CO_(2)and methanol over ceria catalysts

The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts with various textural features and surface properties were prepared by the one-pot synthesis method for the direct DMC synthesis from CO_(2)and methanol,and the structure-performance relationship was investigated in detail.Characterization results revealed that both of surface acid-base properties and the oxygen vacancies contents decreased with the rising crystallinity at increasingly higher calcination temperature accompanied by an unexpectedly volcano-shaped trend of DMC yield observed on the catalysts.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies indicated that the adsorption rate of methanol is slower than that of CO_(2)and the methanol activation state largely influences the formation of key intermediate.Although the enhanced surface acidity-basicity and oxygen vacancies brought by low-temperature calcination could facilitate the activation of CO_(2),the presence of excess strongly basic sites on low-crystallinity sample was detrimental to DMC synthesis due to the preferred formation of unreactive mono/polydentate carbonates as well as the further impediment of methanol activation.Moreover,with the use of 2-cyanopyridine as a dehydration reagent,the DMC synthesis was found to be both influenced by the promotion from the rapid in situ removal of water and the inhibition from the competitive adsorption of hydration products on the same active sites.

On the systematic position of Cacosyndya Kirby(Hymenoptera:Tenthredinidae)with redescription of Cacosyndya dimorpha Freymuth

A peculiar sawfly genus from middle Asia,Cacosyndya Kirby,1883 and the type species Cacosyndya dimorpha(Freymuth,1870)are redescribed and illustrated.The systematic position of this genus in Tenthredinidae is discussed.The females in the genus are apterous,the only known apterous Symphytan,but the male is normally winged.Cacosyndya is not a member of Fenusinae or Heterarthrinae,but a member of Phymatocerini of Blennocampinae,Tenthredinidae as shown by the structure of the antenna,wing venation and body structure.The relationship between Cacosyndya and members of Phymatocerini is briefly discussed.

Stability of second order Hopfield neural networks with time delays

Dynamical behaviors of a class of second order Hopfield neural networks with time delays is investigated.The existence of a unique equilibrium point is proved by using Brouwer's fixed point theorem and the counter proof method,and some sufficient conditions for the global asymptotic stability of the equilibrium point are obtained through the combination of a suitable Lyapunov function and an algebraic inequality technique.

Two new species of Pamphiliidae(Hymenoptera)from Xizang with a key to species from the Himalaya region

Species of Pamphiliidae in the Himalaya region are quite rare.Only seven species belonging to three genera of this family have been recorded.Two new species of Pamphiliidae from Linzhi,Xizang of China are described:Cephalcia xizangica Wei sp.nov.and Onycholyda nigrothorax Wei sp.nov.Cephalcia is recorded from the Himalaya region for the first time.A key to currently known species of Pamphiliidae from Himalayas is provided.

Effect of ground cover changes on solar radiation absorption in Three Northeastern Provinces of China

Background,aim,and scope Solar radiation is the main source of energy for terrestrial ecosystems.Small changes in the absorption of solar radiation at the ground surface can have a significant impact on the climatic environment.Natural and anthropogenic changes in ground cover are important factors affecting the absorption of solar radiation at the ground surface.This phenomenon is particularly pronounced in the mid and high latitudes.In order to quantify the inf luence of surface cover change on the absorption of solar radiation at the surface and to provide a scientific basis for changes in the climatic environment,this paper analyzed ground cover change,ground absorbed solar radiation change and the effect of ground cover change on ground absorbed solar radiation in the Three Northeastern Provinces of China from 2001 to 2018.Materials and methods In this study,the Three Northeastern Provinces of China were used as the study area.Firstly,satellite remote sensing data were used to obtain land cover data and albedo data for Aug.1st of each year in 2001,2005,2010,2015 and 2018.The albedo data were further used to calculate the absorbed solar radiation data at the ground surface.Next,the land cover data were used to count the area changes and shifts of different land classes over the five-year period.The land cover data were overlaid with the surface absorbed solar radiation data to obtain the mean and standard deviation of radiation absorption for different ground classes.The surface absorbed solar radiation data were subtracted to obtain the changes in surface absorbed solar radiation for 2001-2005,2005-2010,2010-2015 and 2015-2018.Ultimately,we used a combination of shifted changes in ground classes and changes in surface absorbed solar radiation data,with unchanged ground classes as a baseline and data such as slope orientation as an aid.We analyzed the effect of ground cover change on surface absorbed solar radiation at regional and pixel point scales.Results(1)The area of woodland and waters in the Three Northeastern Provinces of China increased and then decreased from 2001 to 2018,with an overall increase of 3.96%and 10.51%respectively.Cropland decreased and then increased,with a total decrease of 1.22%.Grassland continued to decrease,with an overall decrease of 19.36%.Building sites increased all the time,with a total increase of 11.08%.The main types of ground cover shifted were woodland,cropland and grassland.The main factors for the change in ground cover were China’s woodland protection policy and the saturation of the total woodland stock.(2)The five ground types absorb solar radiation in the order of waters>building sites>woodland>grassland>cropland.The surface absorption of solar radiation in the Songnen Plain,the Sanjiang Plain and the Songhua River Basin flowing through the Songnen Plain and the Sanjiang Plain varies significantly,by more than 25 W·m^(-2).(3)Changes in the ground cover type affected the absorption of solar radiation energy by the ground surface.There was a clear trend of interconversion between waters and cropland/grassland,cropland and woodland/grassland.In particular,the conversion of waters to both cropland and grassland radiation absorption values decreased significantly,while the opposite increased.The absolute difference between waters and cropland was a maximum of -156.66 W·m^(-2)in 2010-2015,and between waters and grassland was a maximum of 102.36 W·m^(-2) in 2005-2010.The radiative absorption values of woodland and grassland reclamation declined and conversely increased.The absolute difference between woodland and cropland was a maximum of-13.94 W·m^(-2) in 2010-2015 when woodland converted to cropland,and between grassland and cropland was a maximum of 22.36 W·m^(-2) in 2001-2005 when cropland converted to grassland,respectively.Discussion Ground cover changes in the Three Northeastern Provinces of China from 2001-2018 were inextricably linked to natural factors and the inf luence of Chinese national policies.The main inf luencing factors were China’s woodland protection policy,restoration of woodland fire sites,saturation of total woodland,optimization of cropland patterns,sanding of grassland,expansion of water conservancy projects,and urbanization expansion.There were differences in the radiation absorption characteristics of different ground cover types.This was due to the nature of the ground type itself and the regional environment.When ground cover types changed,their ability to absorb solar radiation also changed.The degree of change could be inf luenced by different ground types and different environmental factors.Different spatial scales can also produce variability.We need to consider the effects of ground cover change on the absorption of solar radiation at the surface in an integrated and comprehensive way.Conclusions The Three Northeastern Provinces of China had frequent changes in ground cover from 2001-2018,with the area of grassland decreased by almost 20%.These changes were due to natural environmental change and policies issued by China since the 21st century.The extent to which solar radiation was absorbed by different ground cover types was different,with grassland being the strongest and cropland the least.In the past few years,the Songnen Plain and Sanjiang Plain regions were the most significant changes in the absorption of solar radiation by the ground cover.The change in ground cover type led to a change in solar radiation absorption at the ground surface,with the conversion of waters to cropland or grassland and the conversion of cropland to woodland or grassland showing the greatest change in radiation absorption values,and vice versa.Of these,the absolute difference in the conversion of waters to cropland amounts to-156.66 W·m^(-2) in 2010-2015.The variation in the absorption of solar radiation at the ground surface was related to the characteristics of the ground class itself,but was also limited by the regional environment.Recommendations and perspectives This study showed that surface cover change can affect the absorption of solar radiation at the surface to varying degrees.The unchanged land classes were used as a comparative analysis in this paper,and it was clear from the paper that some of the unchanged land classes showed significant changes in radiation absorption that should be of interest in future studies.

计算机辅助透镜阵列合成全息术的研究

基于合成全息照相和计算机图形学原理,提出利用计算机制作初级体视图序列的方法,并与线阵透镜相结合,实现了计算机和光学联合制作体视全息图.研究了线阵透镜的成像规律和三维数据的计算机显示原理,获得了计算机制体视图与透镜阵列成像的对应关系,根据该对应关系设计了计算程序,并进行了实验验证.

面向远程教育应用的“视频化身虚拟教室”设计

随着计算机、网络和虚拟现实技术的发展,使得新技术支持下基于视频会话的教学互动成为可能。本文针对远程教育中的教学需求,分析了目前虚拟教室的研究现状,在借鉴国内外已有相关研究成果的基础上,对虚拟教室的环境建模、网络架构以及带宽和硬件需求进行了深入的探讨,重点研究了环境建模和视频化身建模的关键技术,给出了一种能真实地重现教学情境、可通过视频化身交互、外设简单且使用方便的虚拟教室解决方案。

体育活动中培养幼儿意志品质途径的探讨

幼儿好动的天性决定了他们对体育活动的爱好,充分发挥体育活动的优势,选择幼儿最感兴趣的领域进行非智力因素——意志品质培养,使幼儿身心得到全面发展。

民族深层心态的吟唱——略论乌热尔图近期创作的忧患意识及其美学嬗变

乌热尔图小说开始就为我们构置了鄂温克族“森林小说”的全景图,提供了一个全新的审美境界。后来随着“寻根文学”的兴起,他的笔曾有过短暂的艰涩,但很快又转变为进一步反映民族的心态负荷和忧患意识,人物形象也更具有悲剧色彩。他审慎地思考本民族的现状和未来,凸现了一个民族该走的自救之路。同时,乌热尔图的美学观念也发生了由“亮色的崇高”到“黑色的悲壮”,由表层的借动物以讴歌人性到深入探究民族命运的嬗变。

金华地区的干旱特征研究

金华地区的干旱具有时间分形结构。无标度区越宽,时间分维值越小,干旱周期越长,干旱灾害越严重。1997～2000年金华地区还可能出现2个左右的千早年,而21世纪的第一个10年(2001～2010)年,试区出现的干旱状态仍属于中等偏多年。

浙教版《科学》与美国《科学探索者》中的STS教育比较——以“地球与宇宙”主题为例

以浙教版《科学》教材与美国主流科学教材《科学探索者》中的“地球与宇宙”主题为例，尝试从STS教育的内容、体现STS教育理念的组织形式与方法两个维度来比较与阐释。在STS教育内容层面，两套教材都关注了科学（s）与社会（s）的关系，也呈现了浙教版《科学》教材在科学（S）与技术（T）关系层面的缺失。对于STS教育理念的呈现方式，一方面表现了对科学探究活动的共同关注，也彰显了浙教版《科学》教材对探究问题的明确性、有效性的不足；另一方面突显了科学史的教育价值。

教育的终极价值与教师的良知

教师为什么而教？教师的使命是什么？何为教师的良知？教师的工作如何促进我们社会的文明与繁盛？为什么教师应当不断地省思自己的行动是否符合教育的终极价值？

创建育人特色的高校物业品牌

品牌代表企业的生命线，反映了核心价值观。创建有育人特色的品牌物业，既是高校物业改革的必然选择，也是赢得校内服务市场最有力的竞争手段，

论科技的伦理论证

科技是人类认识自然的文明成果，科技服务于全人类是科学技术正价值的最大实现，科学技术真正的价值就在于使人不断完善；科技在伦理上应该得到合适的论证；科技的论证应从科技人员道德开始，对科技的研发、成果的运用等应作多方面的论证，科技的伦理论证具有三个双重性特点；建立普世化伦理准则和全球化论证机制是解决科技伦理论证的未来趋势。

Co–Cr–O mixed oxides for low–temperature total oxidation of propane: Structural effects, kinetics, and spectroscopic investigation

A series of Co–Cr–O mixed oxides with different Co/Cr molar ratios are synthesized and tested for the total oxidation of propane.The reaction behaviors are closely related to the structural features of the mixed oxides.The catalyst with a Co/Cr molar ratio of 1:2(1 Co2 Cr)and a spinel structure has the best activity(with a reaction rate of 1.38μmol g^–1 s^–1 at 250℃),which is attributed to the synergistic roles of its high surface acidity and good low-temperature reducibility,as evidenced by the temperature-programmed desorption of ammonia,reduction of hydrogen,and surface reaction of propane.Kinetic study shows that the reaction orders of propane and oxygen on the 1 Co2 Cr catalyst(0.58±0.03 and 0.34±0.05,respectively)are lower than those on the 2 Co1 Cr catalyst(0.77±0.02 and 0.98±0.16,respectively)and 1 Co5 Cr(0.66±0.05 and 1.30±0.11,respectively),indicating that the coverages of propane and oxygen on 1 Co2 Cr are higher than those on the other catalysts due to its higher surface acidity and higher reducibility.In addition,in-situ diffuse reflectance infrared spectroscopic investigation reveals that the main surface species on 1 Co2 Cr during the reaction are polydentate carbonate species,which accumulate on the surface at low temperatures(<250℃)but decompose at relatively high temperatures.

La and CrCo-doped SrTiO_3 as an H_2 evolution photocatalyst for construction of a Z-scheme overall water splitting system

The photocatalytic activity of a semiconductor‐based photocatalyst largely depends on the semiconductor’s intrinsic crystal and electronic properties.We have prepared two types of La and Cr co‐doped SrTiO3photocatalysts(SrTiO3(La,Cr))using the polymerized complex method(PCM)and sol‐gel hydrothermal method(SHM).Under?>420‐nm visible light irradiation,only the Pt‐loaded SrTiO3(La,Cr)prepared by the SHM showed efficient photocatalytic activities for both H2evolution in the presence of an I?sacrificial reagent and for Z‐scheme overall water splitting when it was coupled with the Pt‐loaded WO3in the presence of I?and IO3?as the shuttle redox mediator.The superior photocatalytic activity of SrTiO3(La,Cr)prepared by the SHM has been ascribed to its more negative conduction‐band position,higher carrier concentration,and higher carrier mobility,demonstrating that the design and synthesis of an H2‐evolution photocatalyst with appropriate electronic properties is crucial for achieving Z‐scheme overall water splitting.

新课改下的高中英语情感教学策略

心理学家罗杰斯（Rogers，1983）指出“现代教育的悲剧之一，就是认为惟有认知学习是重要的”。在英语教学中，由于在教学过程中学生的情感没有得到重视和积极的陶冶，滋生了学生对英语的厌学、恶学、恐学的情绪，这显然不能适应社会对人才的需要。进入21世纪以来，在中国新一轮课程改革中，新课程标准明确提出了情感教育目标。为此，教师应该充分认识到情感对教学的重要作用。本文将结合作者过去10年的教学经历，从教学内容、教学组织和教学评价三个方面分析高中英语的情感教学策略。

Understanding morphology-dependent Cu Ox-CeO2 interactions from the very beginning

Elucidation of the CuOx-CeO2 interactions is of great interest and importance in understanding complex CuOx-CeO2 interfacial catalysis in various reactions. In the present work, we have investigated structures and catalytic activity in CO oxidation of CuOx species on CeO2 rods, cubes and polyhedra predominantly exposing {110}+{100}, {100} and {111} facets by the incipient wetness impregnation method with the lowest Cu loading of 0.025%. The structural evolution of CuOx species was found to depend on both the Cu loading and the CeO2 morphology. As the Cu loading increases, CuOx species are deposited preferentially on the surface defect of CeO2 and then aggregate and grow, accompanied by the formation of isolated Cu ions, CuOx clusters strongly/weakly interacting with the CeO2, highly dispersed Cu O nanoparticles, and large Cu O nanoparticles. The isolated Cu^+ species and CuOx clusters weakly interacting with the CeO2 were observed mainly on the O-terminated CeO2{100} facets. Meanwhile, more Cu(I) species are stabilized during CO reduction processes in CuOx/c-CeO2 catalysts than in CuOx/r-CeO2 and CuOx/p-CeO2 catalysts. The catalytic activities of various CuOx/CeO2 catalysts in CO oxidation vary with both the CuOx species and the CeO2 morphology. These results comprehensively elucidate the CuOx-CeO2 interactions and exemplify their morphology-dependence.

Visible light-responsive carbon-decorated p-type semiconductor CaFe_2O_4 nanorod photocatalyst for efficient remediation of organic pollutants

We report the fabrication and photocatalytic property of a composite of C/CaFe2O4nanorods(NRs)in an effort to reveal the influence of carbon modification.It is demonstrated that the photocatalytic degradation activity is dependent on the mass ratio of C to CaFe2O4.The optimal carbon content is determined to be58wt%to yield a methylene blue(MB)degradation rate of0.0058min.1,which is4.8times higher than that of the pristine CaFe2O4NRs.The decoration of carbon on the surface of CaFe2O4NRs improves its adsorption capacity of the MB dye,which is specifically adsorbed on the surface as a monolayer according to the adsorption isotherm analysis.The trapping experiments of the reactive species indicate that superoxide radicals(.O2)are the main active species responsible for the removal of MB under visible‐light irradiation.Overall,the unique feature of carbon coating enables the efficient separation and transfer of photogenerated electrons and holes,strengthens the adsorption capacity of MB,and improves the light harvesting capability,hence enhancing the overall photocatalytic degradation of MB.