Nitrogen and phosphorus co-doped activated carbon induces high density Cu^(+)active center for acetylene hydrochlorination

This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)with different content(mCu-xNP/AC)were manufactured and applied in the acetylene hydrochlorination reaction.It was found that the doping of carriers N and P induced the transformation of Cu^(2+)to Cu^(+),and the catalytic activity was markedly improved.Under the optimal reaction temperature of 220℃,the gas hourly space velocity(GHSV)of C_(2)H_(2)was 90 h^(-1)and V_(HCl):V_(C_(2)H_(2))was 1.15.The initial activity of the 5%Cu-30 NP/AC catalyst reached 95.59%.Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon,which increased the ratio of Cu^+/Cu^(2+).The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C_(2)H_(2)decreased slightly,and the chemisorption capacity for HCl increased significantly,which was the reason for the increased activity of the catalyst.The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.

Ultrasensitive proteomics depicted an in-depth landscape for the very early stage of mouse maternal-to-zygotic transition

Single-cell or low-input multi-omics techniques have revolutionized the study of pre-implantation embryo development.However,the single-cell or low-input proteomic research in this field is relatively underdeveloped because of the higher threshold of the starting material for mammalian embryo samples and the lack of hypersensitive proteome technology.In this study,a comprehensive solution of ultrasensitive proteome technology(CS-UPT)was developed for single-cell or low-input mouse oocyte/embryo samples.The deep coverage and high-throughput routes significantly reduced the starting material and were selected by investigators based on their demands.Using the deep coverage route,we provided the first large-scale snapshot of the very early stage of mouse maternal-to-zygotic transition,including almost 5,500 protein groups from 20 mouse oocytes or zygotes for each sample.Moreover,significant protein regulatory networks centered on transcription factors and kinases between the MII oocyte and 1-cell embryo provided rich insights into minor zygotic genome activation.

Leaf phenotypic variation of endangered plant Tetracentron sinense Oliv.and influence of geographical and climatic factors

To analyze the degree and pattern of phenotypic variation in leaves of Tetracentron sinense Oliv from the perspective of genetic and environmental adaptation and thus contribute to effective evidence-based conservation and management strategies for germplasm resources,we measured 17 morphological and epidermal micromorphological leaf traits from 24 natural populations of T.sinense.Nested analysis of variance,multiple comparison,principal component analysis(PCA),cluster analysis,and correlation analysis were used to explore phenotypic leaf variation among and within populations and potential correlations with geographic and environmental factors.There were significant differences in 17 leaf phenotypic traits among and within populations.The mean phenotypic differentiation coefficient of the 17 traits was 56.34%,and the variation among populations(36.4%)was greater than that within populations(27.2%).The coefficient of variation(CV)of each trait ranged from 4.6 to 23.8%,and the mean was 11.8%.Phenotypic variation of leaves was related to environmental factors such as average annual sunshine hours,average July temperature,and average annual rainfall.The variation changed along gradients of longitude,latitude,and altitude.The PCA clustered the 24 natural populations into four groups.Our study suggests that phenotypic variation in T.sinense occurred primarily among populations,with moderate levels of phenotypic differentiation among populations and low levels of phenotypic variation within populations.The plant’s poor adaptability to the environment is likely an important contributor to its endangerment.Accordingly,conservation strategies are proposed to protect and manage the natural populations of T.sinense.

Sentiment Classification Based on Piecewise Pooling Convolutional Neural Network

Recently,the effectiveness of neural networks,especially convolutional neural networks,has been validated in the field of natural language processing,in which,sentiment classification for online reviews is an important and challenging task.Existing convolutional neural networks extract important features of sentences without local features or the feature sequence.Thus,these models do not perform well,especially for transition sentences.To this end,we propose a Piecewise Pooling Convolutional Neural Network(PPCNN)for sentiment classification.Firstly,with a sentence presented by word vectors,convolution operation is introduced to obtain the convolution feature map vectors.Secondly,these vectors are segmented according to the positions of transition words in sentences.Thirdly,the most significant feature of each local segment is extracted using max pooling mechanism,and then the different aspects of features can be extracted.Specifically,the relative sequence of these features is preserved.Finally,after processed by the dropout algorithm,the softmax classifier is trained for sentiment classification.Experimental results show that the proposed method PPCNN is effective and superior to other baseline methods,especially for datasets with transition sentences.

Differentially expressed genes identified by microarray analysis following oxymatrine treatment of hepatic stellate cell

AIM: To investigate the effects of oxymatrine on the gene expression profile of hepatic stellate cell (HSC) and provide novel insights into the mechanism of oxymatrine against hepatic fibrosis. Methods: HSC was isolated from normal SD by in situ perfusion of collagenase and pronase and density Nycodenz gradient centrifugation. MTT colorimetry was used to study the effect of oxymatrine on the proliferation of HSC. Total RNA and mRNA of quiescent HSC, culture-activated HSC and oxymatrine treated HSC were extracted. Effect of oxymatrine on HSC gene expression profile was detected by oligonucleotide microarray analysis with Affymetrix gene chip rat U230A. Differentially expressed genes were annotated with Gene Ontology (GO) and analyzed with Kyoto encyclopedia of genes and genomes (KEGG) pathway using the Database for Annotation, Visualization and Integrated Discovery. Results: Oxymatrine could inhibit the proliferation of HSC in a dose-dependent manner. A total of 4641 differentially expressed genes were identified by cDNA chip between activated and quiescent HSC, among which 2702 genes were upregulated, and 1939 genes were down-regulated in activated HSC. cDNA microarray uncovered downregulation of 56 genes in response to oxymatrine, the representative genes including alpha 2 type I procollagen, alpha-1 type I collagen, tissue inhibitor of metalloproteinase 1, interleukin 1 beta, early growth response 1, chemokine ligand 2, chemokine ligand 1, CTGF, TGFβ1. The most enriched GO terms included response to wounding, inflammatory response, cell migration, cell motility, wound healing, TGFβ receptor signaling pathway. KEGG pathway analysis revealed that oxymatrine affected the ECM-receptor interaction, focal adhesion, cytokine-cytokine recaptor interaction, TGFβ signaling pathway, MAPK signaling pathway. There were 37 genes upregulated significantly following oxymatrine treatment. The most enriched GO terms included oxidation reduction, negative regulation of lipoprotein oxidation, regulation of lipoprotein oxidation, steroid metabolic process, regulation of lipase activity. Six genes were confirmed with QPCR, consistent with microarray. Conclusion: The mechanism of oxymatrine in inhibiting liver fibrogenesis is associated with multi-genes and multi-pathways regulation.

Direct visualization of structural defects in 2D semiconductors

Direct visualization of the structural defects in two-dimensional(2D)semiconductors at a large scale plays a significant role in understanding their electrical/optical/magnetic properties,but is challenging.Although traditional atomic resolution imaging techniques,such as transmission electron microscopy and scanning tunneling microscopy,can directly image the structural defects,they provide only local-scale information and require complex setups.Here,we develop a simple,non-invasive wet etching method to directly visualize the structural defects in 2D semiconductors at a large scale,including both point defects and grain boundaries.Utilizing this method,we extract successfully the defects density in several different types of monolayer molybdenum disulfide samples,providing key insights into the device functions.Furthermore,the etching method we developed is anisotropic and tunable,opening up opportunities to obtain exotic edge states on demand.

TDLens:Toward an Empirical Evaluation of Provenance Graph-Based Approach to Cyber Threat Detection

To combat increasingly sophisticated cyber attacks,the security community has proposed and deployed a large body of threat detection approaches to discover malicious behaviors on host systems and attack payloads in network traffic.Several studies have begun to focus on threat detection methods based on provenance data of host-level event tracing.On the other side,with the significant development of big data and artificial intelligence technologies,large-scale graph computing has been widely used.To this end,kinds of research try to bridge the gap between threat detection based on host log provenance data and graph algorithm,and propose the threat detection algorithm based on system provenance graph.These approaches usually generate the system provenance graph via tagging and tracking of system events,and then leverage the characteristics of the graph to conduct threat detection and attack investigation.For the purpose of deeply understanding the correctness,effectiveness,and efficiency of different graph-based threat detection algorithms,we pay attention to mainstream threat detection methods based on provenance graphs.We select and implement 5 state-of-the-art threat detection approaches among a large number of studies as evaluation objects for further analysis.To this end,we collect about 40GB of host-level raw log data in a real-world IT environment,and simulate 6 types of cyber attack scenarios in an isolated environment for malicious provenance data to build our evaluation datasets.The crosswise comparison and longitudinal assessment interpret in detail these detection approaches can detect which attack scenarios well and why.Our empirical evaluation provides a solid foundation for the improvement direction of the threat detection approach.

Evaluation of Growth of Agricultural Listed Companies Based on AHP Weighting Method

Agriculture is the foundation of national economy,and agricultural development is related to the rapid development of long-term stability of the society and economy. Agriculture includes farming,forestry,animal husbandry,and fisheries. Agricultural listed company as an agricultural enterprise " leader",which directly affects the development of the entire growth of the agricultural industry development and policy,so the study of agricultural listed company's growth is particularly important. This paper uses AHP weighting method to evaluate 2012 financial data on the growth of agricultural listed companies.

基于ISM的纺织企业粉尘职业危害影响因素分析

通过对纺织企业粉尘职业危害进行现场调查,从人-机-环-管理四个方面分析纺织企业职业危害影响因素,主要包括产尘量、培训教育等12个因素。通过分析各因素之间的相互关系,构建ISM(解释结构模型),借助Matlab2010运用布尔运算,建立递阶结构模型。研究表明,接尘时间和个体防护是直接影响因素,产尘量和管理制度是根本影响因素。ISM分析了系统结构,充分考虑了各影响因素间的深层次关系,利用递阶结构模型清晰的显示影响因素的层次,为纺织企业粉尘职业危害防治提供了理论依据,使防治工作有针对性,防治措施更具有效性。

Macro-superlubricity in sputtered MoS_(2)-based films by decreasing edge pinning effect

To date,MoS_(2) can only be achieved at microscale.Edge pinning effect caused by structure defects is the most obvious barrier to expand the size of structural superlubricity to macroscale.Herein,we plan to pin edge planes of MoS_(2) with nanospheres,and then the incommensurate structure can be formed between adjacent rolling nanoparticles to reduce friction.The sputtered MoS_(2) film was prepared by the physical vapor deposition(PVD)in advance.Then enough Cu_(2)O nanospheres(~40 nm)were generated in situ at the edge plane of MoS_(2) layers by liquid phase synthesis.An incommensurate structure(mismatch angle(θ)=8°)caused by MoS_(2) layers was formed before friction.The friction coefficient of the films(5 N,1,000 r/min)was~6.0×10^(−3) at the most.During friction,MoS_(2) layers pinned on numerous of Cu_(2)O nanoparticles reduced its edge pinning effect and decreased friction.Moreover,much more incommensurate was formed,developing macro-superlubricity.

Promotion effect of epoxy group neighboring single-atom Cu site on acetylene hydrochlorination

Carbon materials have been used as the support for catalysts in the field of acetylene hydrochlorination,the influence of inevitable oxygen-containing moieties on the reaction is often ignored and the mechanism of the oxygen-doping structure remains ambiguous.Herein,we explored the effect of the oxygen-containing group(C-O-C)in the support on the activity of single-atom dispersed Cu catalysts.By immersing the Cu single-atom catalyst in an alkaline solution,the epoxy species on the carbon support was cleaved to obtain a pure ether species while the Cu site was modified to a more electron-deficient state.The turnover frequency value of Cu/O-FLP catalyst with epoxy groups was 1.6-fold higher than that of alkaline treated catalyst.Our result indicated that the epoxy groups could assist adjacent single-atom Cu sites to synergistically promote the adsorption and cleavage of the reactant hydrogen chloride toward form C-OH and Cu-Cl bonds,and reduce the reaction energy barrier.The presence of electron deficient Cu sites and ether species could induce competitive adsorption of the acetylene and hydrogen chloride,thereby reducing the activity of the catalyst.This study highlights the influence of surface oxygen species and the tunability of the support,providing the foundation for the fabrication of higher-activity Cu catalysts for acetylene hydrochlorination.

带缘板修型的静盘深腔型复合封严试验

采用CO_(2)气体体积分数测量法研究一种带缘板修型的静盘深腔型复合封严结构。同时选取轴向封严结构和叠覆封严结构作为比较基准,重点关注主流雷诺数(0.75×10^(5)~9.4×10^(5))、封严流量(流量比0.2%~2.5%)、旋转雷诺数(1.6×10^(5)~8.1×10^(5))等典型工况参数对盘腔内压力分布和封严效率的影响情况;并在此基础上开展了相应的数值研究,获得了封严腔室内详细的流场信息。结果表明:在试验设计工况范围内,主流雷诺数的改变对静叶尾缘和动叶前缘的周向压力分布影响显著。主流雷诺数增加,主流通道内压力升高,主流气体入侵加剧;增加封严流量有利于提高盘腔内压力,从而提升盘腔封严效率,但这对静叶尾缘压力影响较小;增加旋转雷诺数会增大静叶尾缘和动叶叶间通道前缘的静压,加重主流气体入侵,降低盘腔封严效率。相比轴向封严结构,叠覆封严结构由于高半径封严容腔的设置,改变了盘腔流场结构,有效地将主流气体阻隔在封严容腔内,保证了低半径盘腔的封严效率在80%以上。新型封严结构的静盘深腔和缘板造型设置,不仅保证了低半径盘腔的封严效率在85%以上,还能提高高半径处封严容腔的封严效率,在低流量比(0.2%)工况下,其封严容腔区域的封严效率提升了10%。

Manipulating micro-electric field and coordination-saturated site configuration boosted activity and safety of frustrated single-atom Cu/O Lewis pair for acetylene hydrochlorination

Simultaneously boosting acetylene hydrochlorination activity and avoiding formation of explosive copper acetylide over Cu-based catalyst,which represented a promising alternative to Hg-based and noble metal catalysts,remained challenging.Herein,we fabricated a frustrated single-atom Cu/O Lewis pair catalyst(Cu/O-FLP)by coupling epoxide group(C-O-C)with atomdispersed Cu-cis-N_(2)C_(2)Cl center to address this challenge.The basic epoxy site modulated the electron-deficient state of Lewisacidic Cu center and paired with the Cu-cis-N_(2)C_(2)Cl moiety to preferentially break HCl into different electronegative Cu-Clδ-and C-O-H^(δ+)intermediates,which further induced both an extra localized electric field to polarize acetylene and a upshift of the dband center of catalyst,thereby promoting adsorption and enrichment of acetylene by enhancing the dipolar interaction between acetylene and active intermediates.Moreover,the generated Cu-Clδ-and C-O-H^(δ+)drastically reduced the energy barrier of ratelimiting step and made vinyl chloride easier to desorb from the Lewis-basic oxygen-atom site rather than traditional Lewis-acidic Cu center.These superiorities ensured a higher activity of Cu/O-FLP compared with its counterparts.Meanwhile,preferential dissociation of HCl endowed single-atom Cu with the coordination-saturated configuration,which impeded formation of explosive copper acetylide by avoiding the direct interaction between Cu and acetylene,ensuring the intrinsic safety during catalysis.

Control of squealer-tip leakage flow with perforated-rib coolant injection in an axial turbine cascade

A novel perforated-rib configuration is proposed for controlling the tip leakage flow at the rotor tip of an axial turbine.Three perforated-rib layouts are considered,wherein a perforated rib is installed at(A)the Suction-Side squealer(SS-rib),(B)the Pressure-Side squealer(PS-rib),and(C)the additional squealer along the blade Camber Line(CL-rib).A numerical method is used to show how the novel rib layouts affect the aerodynamic performance of the tip leakage flow.Results show that the coolant jets issuing from the perforated-rib injection holes penetrate deeper into the tip clearance than those in the baseline squealer-tip case,and how the perforated-rib coolant injection affects the tip leakage flow depends strongly on the rib layout.The PS-rib and CL-rib layouts appear promising for controlling the tip leakage flow,playing a significant role in reducing the total pressure loss and improving the turbine blade’s isentropic efficiency.In particular,under an injection mass flow ratio of 1%and a tip clearance of 1%blade span,the PS-rib layout reduces the leakage mass flow rate by 27%and increases the isentropic efficiency by 1.25%compared with those in the baseline squealer-tip case.Meanwhile,the advantages of the PS-rib layout in tip leakage control are confirmed under small and large tip clearances.

Effects of trifluoromethanesulfonic acid ligand on the Zinc-based catalysts for the acetylene hydration

Developing an efficient Zn-based catalyst modified with Trifluoromethanesulfonic acid(Tf OH)ligand is extremely desirable for the acetylene hydration reaction.In this paper,with the use of a simple impregnation method,a series of Zn-Tf OH/AC catalysts were synthesized,and the Zn-1.5Tf OH/AC catalyst demonstrated the optimal catalytic performance with 96%acetylene conversion in the hydration of acetylene.The X-ray absorption fine structure(XAFS)spectra of the fresh Zn-1.5Tf OH/AC catalysts demonstrated the establishment of the Zn-O_(4)coordination structure.According to the characterization results,Tf OH ligands effectively inhibited carbon accumulation and Zinc loss,improved acidic sites and the dispersion of active metal,and produced more catalytic active site.Furthermore,the hydration reaction mechanism of Zn-Tf OH/AC catalyst with Zn(OTf)_(2),Tf O-Zn Cl,and Tf O-Zn OH complex configurations was explored by the Density Functional Theory(DFT)method,which showed that the activation barrier increased sequentially TfO-ZnOH<Zn(OTf)_(2)<Tf O-Zn Cl.Importantly,the OH-in TfO-ZnOH is involved in the reaction and regenerated by the dissociation of H_(2)O,which lowers the energy barrier.This will provide a reference to design more efficient nonmercury catalysts for acetylene hydration.

Application of SnO_(x)/AC catalyst for the acetylene hydrochlorination

In this work,SnO_(x)/activated carbon(AC)was synthesized by hydrothermal method,which was applied to acetylene hydrochlorination.Characterizations showed the SnO_(x)nanoparticles were uniformly dispersed on the carbon,with the coexistence of SnO and SnO_(2).The acetylene conversion of SnO_(x)/AC was 75%,much higher than that of SnCl_(4)/AC.It was shown that the adsorption of reactants on SnO_(x)was stronger than on SnCl_(4).Theoretical calculations showed the adsorption energies of reactants on SnO_(x)were thermodynamically favorable and suggested that Sn^(4+)and Sn^(2+)in SnO_(x)have different adsorption capacities for reactants.Through adjusting the valence ratio of SnO_(x),SnO_(x)/AC O 4 h(O for oxidation)exhibited the best catalytic performance and had the strongest adsorption capacity for the reactants.However,the SnO_(x)/AC catalyst was easily deactivated during acetylene hydrochlorination due to the loss of Sn.The doping of N effectively reduced the loss of Sn and improved the stability of the catalyst due to the anchoring effect of N on the SnO_(x)particles.

Neuroinflammation in Parkinson’s disease and its potential as therapeutic target

Parkinson’s disease(PD),the second most common age-associated neurodegenerative disorder,is characterized by the loss of dopaminergic(DA)neurons and the presence ofα-synuclein-containing aggregates in the substantia nigra pars compacta(SNpc).Chronic neuroinflammation is one of the hallmarks of PD pathophysiology.Postmortem analyses of human PD patients and experimental animal studies indicate that activation of glial cells and increases in pro-inflammatory factor levels are common features of the PD brain.Chronic release of proinflammatory cytokines by activated astrocytes and microglia leads to the exacerbation of DA neuron degeneration in the SNpc.Besides,peripheral immune system is also implicated in the pathogenesis of PD.Infiltration and accumulation of immune cells from the periphery are detected in and around the affected brain regions of PD patients.Moreover,inflammatory processes have been suggested as promising interventional targets for PD and even other neurodegenerative diseases.A better understanding of the role of inflammation in PD will provide new insights into the pathological processes and help to establish effective therapeutic strategies.In this review,we will summarize recent progresses in the neuroimmune aspects of PD and highlight the potential therapeutic interventions targeting neuroinflammation.

An active vibration control method based on energy-fuzzy for cantilever structures excited by aerodynamic loads

In wind tunnel tests for the full-model fixed with sting,the low structural damping of the long cantilever sting results in destructive low-frequency and large-amplitude vibration.In order to obtain high-quality wind tunnel test data and ensure the safety of wind tunnel tests,an energy-fuzzy adaptive PD(Proportion Differentiation)control method is proposed.This method is used for active vibration control of a cantilever structure under variable aerodynamic load excitation,and real-time adjustment of parameters is achieved according to the system characteristics of vibration energy.Meanwhile,a real-time method is proposed to estimate the real-time vibration energy through the vibration acceleration signal,and the average exciting power of aerodynamic load is obtained by deducting the part of the power contributed by the vibration suppressor from the total power.Furthermore,an energy-fuzzy adaptive PD controller is proposed to achieve adaptive control to the changes of the aerodynamic load.Besides,the subsonic and transonic experiments were carried out in wind tunnel,the results revealed that comparing to fixed gain PD controllers,the energy-fuzzy adaptive PD controller maintains higher performance.

Gate-tunable large-scale flexible monolayer MoS_(2)devices for photodetectors and optoelectronic synapses

Photodetectors and optoelectronic synapses are vital for construction of artificial visual perception system.However,the hardware implementations of optoelectronic-neuromorphic devices based on conventional architecture usually suffer from poor scalability,light response range,and limited functionalities.Here,large-scale flexible monolayer MoS_(2)devices integrating photodetectors and optoelectronic synapses over the entire visible spectrum in one device have been realized,which can be used in photodetection,optical communication,artificial visual perception system,and optical artificial neural network.By modulating gate voltages,we enable MoS_(2)-based devices to be photodetectors and also optoelectronic synapses.Importantly,the MoS_(2)-based optoelectronic synapses could implement many synaptic functions and neuromorphic characteristics,such as short-term memory(STM),long-term memory(LTM),paired-pulse facilitation(PPF),long-term potentiation(LTP)/long-term depression(LTD),and“learning-experience”behavior.Furthermore,an associative learning behavior(the classical conditioning Pavlov’s dog experiment)was emulated using paired stimulation of optical and voltage pulses.These results facilitate the development of MoS_(2)-based multifunctional optoelectronic devices with a simple device structure,showing great potential for photodetection,optoelectronic neuromorphic computing,human visual systems mimicking,as well as wearable and implantable electronics.

A novel and effective Zn/PEI-MCM catalyst for the acetylene hydration to acetaldehyde

MCM-41 material was modified by polyethyleneimine (PEI) using ultrasonic assisted impregnation method with different PEI loading (P-MCM-x, x=0–15 wt%). The synthesised P-MCM-x materials and corresponding Zn/P-MCM-x catalysts were characterised by FTIR, XRD, TEM, BET, XPS, TG and H2-TPR, as well as their catalytic performance in the hydration of acetylene was investigated. The results showed that the modified materials retained the mesoporous structure with good thermostability, and the corresponding Zn/P-MCM-x displayed the higher catalytic performance than that of Zn/MCM-41 catalyst, especially for the Zn/P-MCM-12 catalyst with about 88%C2H2 conversion and 85%selectivity, and the optimal content of PEI is 12 wt%. More importantly, the introduction of PEI enhanced metal-support interaction to make the better metal dispersion and more active sites, and the charge transfer from N atom to Zn species. These all would be responsible for the high activity of the modified Zn catalysts in the acetylene hydration.