Zonal activation of molecular carbon dioxide and hydrogen over dual sites Ni-Co-MgO catalyst for CO_(2) methanation:Synergistic catalysis of Ni and Co species

An in-depth mechanism in zonal activation of CO_(2)and H2molecular over dual-active sites has not been revealed yet.Here,Ni-Co-MgO was rationally constructed to elucidate the CO_(2)methanation mechanism.The abundant surface nickel and cobalt components as active sites led to strong Ni-Co interaction with charge transfer from nickel to cobalt.Notably,electron-enriched Coδ-species participated in efficient chemisorption and activation of CO_(2)to generate monodentate carbonate.Simultaneously,plentiful available Ni0sites facilitated H2dissociation,thus CO_(2)and H2were smoothly activated at zones of Coδ-species and Ni0,respectively.Detailed in situ DRIFTS,quasi situ XPS,TPSR,and DFT calculations substantiated a new formate evolution mechanism via monodentate carbonate instead of traditional bidentate carbonate based on synergistic catalysis of Coδ-species and Ni0.The zonal activation of CO_(2)and H2by tuning electron behaviors of double-center catalysts can boost heterogeneous catalytic hydrogenation performance.

有机化学实验的副产物分析引导实验创新与科研素养培育——以4-苯基丁-2-酮合成实验为例

用乙酰乙酸乙酯和氯化苄合成4-苯基丁-2-酮是经典的有机化学实验,但该实验的产率仅有20%–30%。本文记录了教师通过引导学生分离实验中的副产物,确定其为2,2-二苄基-3-氧代丁酸乙酯,并分析该副产物产生的原因,进而启发学生创新实验方案将产率提高至57.5%的过程。该教学实践不仅引导学生进行实验创新,而且培养了学生的科研素养。

活化高熵氧化物中部分金属位点显著增强热催化和电催化

高熵氧化物(HEOs)作为一种新兴材料受到科研工作者的广泛关注,并推动了高熵陶瓷材料(碳化物、硫化物、氟化物等)的发展及其在介电、磁学、储氢以及能源转化等领域中的应用.其中,HEOs由于丰富的活性位点、可调节的比表面积、稳定的晶体结构、独特的几何相容性和电子结构等特性在催化化学领域展示出广阔的应用前景.然而,受制于HEOs的结构特点和难以精确调控的物化性质,当前的研究主要围绕HEOs制备方法的探索及其在不同催化反应中的尝试.在以HEOs为基体进行的催化反应中,也有将贵金属与HEOs复合进行催化剂制备和催化应用的研究报道,但效果并不理想.因此,如何直接对HEOs进行改性并提升其催化性能是低成本高效促进HEOs在催化领域发展的重要途径.本文首先采用固相燃烧法制备CuCoNiZnAl HEOs,同时在制备过程中加入硫脲后通过焙烧处理来进行物化性质的原位调节(记为CuCoNiZnAl-T),随后采用碱液对CuCoNiZnAl-T处理来实现形貌的改变和物化性质的进一步优化(记为CuCoNiZnAl-T-NaOH).X射线粉末衍射结果表明,硫脲添加和碱处理未改变CuCoNiZnAl-T-NaOH的晶型结构.电镜结果表明,CuCoNiZnAl和CuCoNiZnAl-T均呈现出较大的颗粒状,而CuCoNiZnAl-T-NaOH具有大片层形貌结构和明显的晶格扭曲.此外,H_(2)程序升温还原、X射线光电子能谱和He程序升温脱附结果表明,CuCoNiZnAl-T-NaOH不仅具有容易还原的铜、镍、钴的氧化物物种,而且具有高含量和更活泼的晶格氧物种.因此,CuCoNiZnAl-T-NaOH在活性测试中展示出较好的CO_(2)加氢和CO氧化催化性能.其中CuCoNiZnAl-T-NaOH在催化CO氧化反应中,当转化率达到50%时所需转化温度为176℃,比相同条件下CuCoNiZnAl和CuCoNiZnAl-T作为催化剂达到同样催化效果时所需转化温度分别低36和21℃.此外,当CuCoNiZnAl-T-NaOH用作锂氧电池电极材料时也展示出较好的电催化活性(放电/充电容量为12049/9901 mAh/g)和循环稳定性(2500 h).随后,以CO_(2)加氢反应为研究对象,进一步采用近常压X射线光电子能谱进行反应机理分析,结果表明,相对于CuCoNiZnAl而言,CuCoNiZnAl-T在CO_(2)加氢反应过程中表面镍和钴的氧化物物种与活化的晶格氧之间更容易进行电子转移,这种增强的电子传输能力和更强的CO_(2)吸附能力有利于CO_(2)加氢反应的进行.推断这种电子传输能力的提升同样有利于CO氧化和锂氧电池性能的提升.综上,本文为HEOs催化剂的简洁制备和物化性质改善提供了技术借鉴,有望进一步推进HEOs的改性制备和在其他领域的功能化应用发展.

Selective capture of Tl2O from flue gas with formation of p-n junction on V_(2)O_(5)-WO_(3)/TiO_(2)catalyst under working conditions

Thallium(Tl)compounds,highly toxic to biology,are usually released into flue gas during fossil/minerals combustion,and further distributed in water and soil.In this work,we fundamentally investigated the capture of gaseous Tl_(2)O by industrial V2O5-WO3/TiO_(2)catalyst under working condition in Tl-containing flue gas.Experimental and theoretical results indicated that the Tl_(2)O has significant electron-feeding capacity and easily donate electron to unoccupied orbitals of TiO_(2),leading to dismutation of Ti 2p and inartificial formation of p-n junction on TiO_(2)surface,which prompted Tl_(2)O selectively interacted with TiO_(2)in flue gas.Herein,we proposed and verified an effective way to capture gaseous Tl_(2)O,which offered almost the best choice to eliminate Tl emission from flue gas and expanded the function of the TiO_(2)-based catalyst.The formation of p-n junction on commercial V2O5-WO3/TiO_(2)catalyst under working condition was revealed for the first time,which can be a valuable reference for both heterocatalysis and electro/photocatalysis.

Investigation of a facile plasma-driven method for in situ cleaning of metal-based contamination

Self-cleaning of tin contaminants was realized utilizing a self-driven hydrogen plasma.Cleaning rates of 0.7-6 nm min-1were achieved for removal of discontinuous tin particles at different powers.The analysis of topography and cross-sectional morphology revealed that the removal of tin particles was achieved through top-down cleaning with hydrogen plasma,where the upper part of spherical tin particles was always more intensely cleaned under the synergistic effect of hydrogen atoms and ions due to the vertical incidence of ions to the substrate during the whole cleaning process.Redeposition of tin atoms caused by physical sputtering and its promotion of the chemical cleaning effect was observed for the first time.Reflectance recovery measurements during cleaning and surface analysis of the substrate after cleaning indicated that nondestructive cleaning with a reflectance loss of less than 1%can be achieved at a relatively low power of120 W.Plasma-induced substrate damage,such as holes and valleys,reduced the reflectance of the substrate when cleaning was performed at a high power greater than 120 W,so this method should only be considered for application under conditions without substrate exposure.This study provides a comprehensive understanding of the removal of discontinuous tin particles using the in situ self-driven plasma cleaning method,and also provides meaningful guidance for the extension of this method in other potential fields of application.

Fusing Supervised and Unsupervised Measures for Attribute Reduction

It is well-known that attribute reduction is a crucial action of rough set.The significant characteristic of attribute reduction is that it can reduce the dimensions of data with clear semantic explanations.Normally,the learning performance of attributes in derived reduct is much more crucial.Since related measures of rough set dominate the whole process of identifying qualified attributes and deriving reduct,those measures may have a direct impact on the performance of selected attributes in reduct.However,most previous researches about attribute reduction take measures related to either supervised perspective or unsupervised perspective,which are insufficient to identify attributes with superior learning performance,such as stability and accuracy.In order to improve the classification stability and classification accuracy of reduct,in this paper,a novel measure is proposed based on the fusion of supervised and unsupervised perspectives:(1)in terms of supervised perspective,approximation quality is helpful in quantitatively characterizing the relationship between attributes and labels;(2)in terms of unsupervised perspective,conditional entropy is helpful in quantitatively describing the internal structure of data itself.In order to prove the effectiveness of the proposed measure,18 University of CaliforniaIrvine(UCI)datasets and 2 Yale face datasets have been employed in the comparative experiments.Finally,the experimental results show that the proposed measure does well in selecting attributes which can provide distinguished classification stabilities and classification accuracies.

聚碳酸酯型形状记忆聚氨酯的合成与表征

以碳化二亚胺改性MDI(MM103)、1,4-丁二醇(BDO)和聚碳酸1,6-己二醇酯二醇(PCDL)为原料,采用一步熔融法合成了系列聚碳酸酯型形状记忆聚氨酯弹性体(PCPU)。通过红外测试、差示扫描量热测试、硬度测试、拉伸强度测试、吸水率测试和形状记忆性能测试研究了硬段含量对材料性能的影响。结果表明,随着硬段含量的增加,PCPU的硬度逐渐增大,吸水率、拉伸强度和断裂伸长率均是先增加后减小;硬段含量为15%～20%时,PCPU的形状固定率和形状恢复率最高。

Organic matter enrichment in the first member of the Xiagou formation of the lower Cretaceous in the Jiuquan Basin, China

The sources and enrichment of organic matter in a sediment core in the first member of the Xiagou Formation(K_1g^1) from the Chang 2-2 borehole of the Jiuquan Basin,NW China,have been examined using Rock-Eval,maceral,carbon isotopes and biomarker data.This data indicates that highly variable organic matter sources and preservation conditions in response to climate change.TOC content,HI,and δ^(13)C value were strongly correlated with the abundance of gammacerane,woody organic matter content,steranes/hopanes ratio,and C_(29) sterane content.This correlation demonstrates the importance that the control of the salinity of the depositional environment and organic matter sources can have upon the enrichment,type,and carbon isotopic composition of organic matter.In the Jiuquan Basin's relatively high temperature and arid climate,high salinity lakes with high primary productivity of algae,planktons,and bacteria,and good organic matter preservation conditions(anoxic bottom water) resulted in the enrichment of isotopically-light algae-bacterial organic matter.In the Jiuquan Basin's regions with a relatively low temperature and wet climate,fresh lakes with low primary productivity of algae,planktons,and bacteria received significant terrigenous high plants input,resulting in the deposition of a low abundance of isotopically heavier terrestrial organic matter.

TOEPLITZ OPERATORS WITH POSITIVE OPERATOR-VALUED SYMBOLS ON VECTOR-VALUED GENERALIZED FOCK SPACES

In this article,we study some characterizations of Toeplitz operators with positive operator-valued function as symbols on the vector-valued generalized Bargmann-Fock spaces Fψ^2.Main results including Fock-Carleson condition,bounded Toeplitz operators,compact Toeplitz operators,and Toeplitz operators in the Schatten-p class are all considered.

Immunization with Cytomegalovirus Envelope Glycoprotein M and Glycoprotein N DNA Vaccines can Provide Mice with Complete Protection against a Lethal Murine Cytomegalovirus Challenge

Human cytomegalovirus virions contain three major glycoprotein complexes (gC I, II, III), all of which are required for CMV infectivity. These complexes also represent major antigenic targets for anti-viral immune responses. The gC II complex consists of two glycoproteins, gM and gN. In the current study, DNA vaccines expressing the murine cytomegalovirus (MCMV) homologs of the gM and gN proteins were evaluated for protection against lethal MCMV infection in a mouse model. Humoral and cellular immune responses, spleen viral titers, and mice survival and body-weight changes were examined. The results showed that immunization with gM or gN DNA vaccine alone was not able to offer good protection, whereas co-immunization with both gM and gN induced an effective neutralizing antibody response and cellular immune response, and provided mice with complete protection against a lethal MCMV challenge. This study provides the first in vivo evidence that the gC II (gM-gN) complex may be able to serve as a protective subunit antigen for future HCMV vaccine development.

Ericoid mycorrhizal fungus enhances microcutting rooting of Rhododendron fortunei and subsequent growth

Adventitious root(AR)formation is a unique feature of plant reproduction and plays a vital role in crop production as many horticultural and forestry plants are propagated through cuttings.A growing number of reports have shown that microbes,particularly mycorrhizal fungi are able to promote AR formation,but the underlying mechanisms remain largely unclear.This study established an in vitro culture system and investigated AR formation in microcuttings of Rhododendron fortunei Lindl.inoculated with Oidiodendron maius Barron Om19,an ericoid mycorrhizal fungus strain.Hormones and precursors involved in the biosynthesis of indole-3-acetic acid(IAA)in Om19 mycelium were analyzed.Om19 was able to produce a large quantity of tryptophan(Trp)and also indole-3-pyruvate(IPA)and IAA,indicating that IAA biosynthesis in Om19 could be through a Trp-dependent pathway.After inoculation of Om19,ARs were quickly formed in microcuttings.Symbiosis related genes were activated in ARs,and Om19 effectively colonized the roots.YUC3,a key gene in plant biosynthesis of IAA and genes involved in nitrogen(N)uptake and metabolism,phosphorus(P)uptake were highly upregulated.Plants absorbed significantly greater quantity of mineral nutrients,and their growth was substantially enhanced compared to the control plants without Om19 inoculation.A working model for Om19 enhanced AR formation was proposed.The rapid formation of ARs in cuttings could be due in part to the induction of IAA biosynthesized by Om19 and also attributed to Trp catalyzed biosynthesis of IAA in plants.AR formation,in turn,provided Om19 preferred sites for colonization.Our study suggested that in addition to promoting AR formation,Om19 could potentially be used as a new biofertilizer for enhancing production of ericaceous plants,such as blueberry,cranberry,and rhododendron.

Interaction of an unwetted liquid Li-based capillary porous system with high-density plasma

This study examined the effects of plasma irradiation on an unwetted liquid lithium-based capillary porous system(Li-CPS). The Li-CPS was irradiated with high-density Ar plasma using a linear plasma device at Sichuan University for Plasma Surface Interaction. The high-speed camera, Langmuir probe, and multi-channel spectrometer were used to characterize the effects of plasma irradiation. Upon Ar plasma irradiation, liquid Li drops were formed on the surface of the unwetted Li-CPS. Immediately after this irradiation, the drops fractured and were ejected into the plasma within ~20 ms scale, which is not observed before to the best of our knowledge. Related results showed that the ejection behavior of Li could effectively cool electron temperature and reduce incident heat flux by ~30% and correspondingly matrix temperature ~150 ℃, revealing an enhanced vapor shielding effect. The involved internal mechanism and physical processes deserve further investigations.

Cleaning of nitrogen-containing carbon contamination by atmospheric pressure plasma jet

Atmospheric pressure plasma jet(APPJ)was used to clean nitrogen-containing carbon films(C–N)fabricated by plasma-assisted chemical vapor deposition method employing the plasma surface interaction linear device at Sichuan University(SCU-PSI).The properties of the contaminated films on the surface of pristine and He-plasma pre-irradiated tungsten matrix,such as morphology,crystalline structure,element composition and chemical structure were characterized by scanning electron microscopy,grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy.The experimental results revealed that the removal of C–N film with a thickness of tens of microns can be realized through APPJ cleaning regardless of the morphology of the substrates.Similar removal rates of 16.82 and 13.78μm min^(-1)were obtained for C–N films deposited on a smooth pristine W surface and rough fuzz-covered W surface,respectively.This is a remarkable improvement in comparison to the traditional cleaning method.However,slight surface oxidation was found after APPJ cleaning,but the degree of oxidation was acceptable with an oxidation depth increase of only 3.15 nm.Optical emission spectroscopy analysis and mass spectrometry analysis showed that C–N contamination was mainly removed through chemical reaction with reactive oxygen species during APPJ treatment using air as the working gas.These results make APPJ cleaning a potentially effective method for the rapid removal of C–N films from the wall surfaces of fusion devices.

Enhanced Protective Efficacy of H5 Subtype Influenza Vaccine with Modification of the Multibasic Cleavage Site of Hemagglutinin in Retroviral Pseudotypes

Traditionally, the multibasic cleavage site (MBCS) of surface protein H5-hemagglutinin (HA) is converted to a monobasic one so as to weaken the virulence of recombinant H5N1 influenza viruses and to produce inactivated and live attenuated vaccines. Whether such modification benefits new candidate vaccines has not been adequately investigated. We previously used retroviral vectors to generate wtH5N1 pseudotypes containing the wild-type HA (wtH5) from A/swine/Anhui/ca/2004 (H5N1) virus. Here, we generated mtH5N1 pseudotypes, which contained a mutant-type HA (mtH5) with a modified monobasic cleavage site. Groups of mice were subcutaneously injected with the two types of influenza pseudotypes. Compared to the group immunized with wtH5N1 pseudotypes, the inoculation of mtH5N1 pseudotypes induced significantly higher levels of HA specific IgG and IFN-γ in immunized mice, and enhanced protection against the challenge of mouse-adapted avian influenza virus A/Chicken/Henan/12/2004 (H5N1). This study suggests modification of the H5-hemagglutinin MBCS in retroviral pseudotypes enhances protection efficacy in mice and this information may be helpful for development of vaccines from mammalian cells to fight against H5N1 influenza viruses.

Gender-Specific Multi-Task Micro-Expression Recognition Using Pyramid CGBP-TOP Feature

Micro-expression recognition has attracted growing research interests in the field of compute vision.However,micro-expression usually lasts a few seconds,thus it is difficult to detect.This paper presents a new framework to recognize micro-expression using pyramid histogram of Centralized Gabor Binary Pattern from Three Orthogonal Panels(CGBP-TOP)which is an extension of Local Gabor Binary Pattern from Three Orthogonal Panels feature.CGBP-TOP performs spatial and temporal analysis to capture the local facial characteristics of micro-expression image sequences.In order to keep more local information of the face,CGBP-TOP is extracted based on pyramid subregions of the micro-expression video frame.The combination of CGBP-TOP and spatial pyramid can represent well and truly the facial movements of the micro-expression image sequences.However,the dimension of our pyramid CGBP-TOP tends to be very high,which may lead to high data redundancy problem.In addition,it is clear that people of different genders usually have different ways of micro-expression.Therefore,in this paper,in order to select the relevant features of micro-expression,the gender-specific sparse multi-task learning method with adaptive regularization term is adopted to learn a compact subset of pyramid CGBP-TOP feature for micro-expression classification of different sexes.Finally,extensive experiments on widely used CASME II and SMIC databases demonstrate that our method can efficiently extract micro-expression motion features in the micro-expression video clip.Moreover,our proposed approach achieves comparable results with the state-of-the-art methods.

Are the H5N1 Viruses Prepared for Inter-human Transmission?

Since 1997,highly pathogenic avian influenza (HPAI) H5N1 viruses have caused serious outbreaks in poultry and markets,In human,overall mortality in HPAI H5N1 infection exceeds 60％,but human to human transmission is limited and has been only reported within family members[7,8].There is much concern as to whether H5N1 can enhance its transmission among humans through genetic variation.Further,there is an urgent need to discover the potential mutations in viral proteins that are responsible for inter-human transmission.

Colloidal quantum dot lasers and hybrid integrations

Colloidal quantum dots (CQDs) are semiconductor nanocrystalswith diameters about 2 to 20 nm. At such nanoscales,the CQDs exhibit obvious quantum and dielectric confinementeffects[1]. The CQDs are usually composed of II–VI, III–V,and IV–VI semiconductors fabricated by the low-cost wet chemicalsynthetic methods. The emission wavelengths of CQDs,which can be easily tuned by the sizes, shapes, and compositions,have already covered the whole range of the visible andnear-infrared (NIR) spectra (from 440 to 1530 nm). Owing tothe low-cost fabrications, high quantum yields (QYs^100%), tunableemission wavelengths, and outstanding stability, the solution-processable CQDs can act as the nanoscale buildingblocks with large gains, and they have attracted enormous attentionin the lasing applications in the past decade.

A snapshot of the Chinese SOL Project

In 2003, the International Solanaceae Project （SOL） was initiated by an international consortium of ten countries including Korea, China, the United Kingdom, India, the Netherlands, France, Japan, Spain, Italy and the United States. The first major effort of the SOL aimed to produce a DNA sequence map for euchromatin regions of 12 chromosomes of tomato （Solanum lycopersicum） before 2010. Here we present an update on Chinese effort for sequencing the euchromatin region of chromosome 3.

Erosion research of CX-2002U carbon composites under low-temperature high-flux hydrogen plasma

The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma flux.When the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would change.Then the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed dramatically.Moreover,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias voltage.Based on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.