Modified electronic structure and enhanced hydroxyl adsorption make quaternary Pt-based nanosheets efficient anode electrocatalysts for formic acid-/alcohol-air fuel cells

Surface/interface engineering of a multimetallic nanostructure with diverse electrocatalytic properties for direct liquid fuel cells is desirable yet challenging.Herein,using visible light,a class of quaternary Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)ultrathin nanosheets is fabricated and used as high-performance anode electrocatalysts for formic acid-/alcohol-air fuel cells.The modified electronic structure of Pt,enhanced hydroxyl adsorption,and abundant exterior defects afford Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C high intrinsic anodic electrocatalytic activity to boost the power densities of direct formic acid-/methanol-/ethanol-/ethylene glycol-/glycerol-air fuel cells,and the corresponding peak power density of Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C is respectively 129.7,142.3,105.4,124.3,and 128.0 mW cm^(-2),considerably outperforming Pt/C.Operando in situ Fourier transform infrared reflection spectroscopy reveals that formic acid oxidation on Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C occurs via a CO_(2)-free direct pathway.Density functional theory calculations show that the presence of Ag,Bi,and Te in Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)suppresses CO^(*)formation while optimizing dehydrogenation steps and synergistic effect and modified Pt effectively enhance H_(2)O dissociation to improve electrocatalytic performance.This synthesis strategy can be extended to 43 other types of ultrathin multimetallic nanosheets(from ternary to octonary nanosheets),and efficiently capture precious metals(i.e.,Pd,Pt,Rh,Ru,Au,and Ag)from different water sources.

Versatile and controlled quantum teleportation network

A quantum teleportation network involving multiple users is essential for future quantum internet.So far,controlled quantum teleportation has been demonstrated in a three-user network.However,versatile and controlled quantum teleportation network involving more users is in demand,which satisfies different combinations of users for practical requirements.Here we propose a highly versatile and controlled teleportation network that can switch among various combinations of different users.We use a single continuous-variable six-partite Greenberger-Horne-Zeilinger(GHZ)state to realize such a task by choosing the different measurement and feedback operations.The controlled teleportation network,which includes one sub-network,two sub-networks and three sub-networks,can be realized for different application of user combinations.Furthermore,the coherent feedback control(CFC)can manipulate and improve the teleportation performance.Our approach is flexible and scalable,and would provide a versatile platform for demonstrations of complex quantum communication and quantum computing protocols.

热处理工艺对FGH96合金惯性摩擦焊组织与显微硬度的影响

采用惯性摩擦焊接方法进行了FGH96高温合金焊接,借助光学显微镜、扫描电子显微镜、显微硬度仪对焊态和热处理态FGH96惯性摩擦焊接头组织和显微硬度进行了研究.结果表明,焊缝中心区内发生完全动态再结晶,再结晶晶粒细小,晶粒尺寸为4.6μm±0.3μm,且二次γ′相完全溶解,导致硬度低于母材组织.随着远离焊缝,二次γ′相含量逐渐增加,距焊缝1.5 mm后γ′相体积分数基本保持不变,但γ′相形貌由球形逐渐向立方体转变,导致硬度逐渐增加.经热处理后,焊缝区域内二次γ′相的含量与形貌变化规律与焊态相似,但热处理后基材晶粒尺寸从11.4μm±0.3μm增大至13.5μm±1.0μm,是导致热处理后基材硬度较焊态较低的原因;另外热处理后三次γ′相的析出是导致热处理态焊缝硬度高于焊态的原因.

高职院校自主招生管理系统的设计与实现

近年来,高职院校自主招生管理系统得到了广泛应用。高职院校在设计自主招生管理系统时,需要考虑系统功能的需求、系统非功能的需求以及系统运行的可行性。高职院校的自主招生管理系统的优势是显而易见的,在此基础上,文中分析了高职院校自主招生管理系统的优势和重要性。

ZIF-67膜在AZ31镁合金微弧氧化防腐涂层上的合成

为了提高AZ31镁合金的耐蚀性和金属有机骨架MOFs涂层的结合力,通过在AZ31镁合金微弧氧化(MAO)涂层上原位生长,制备MAO/ZIF-67(微弧氧化/钴基金属有机骨架)复合涂层。结果表明,具有菱形十二面体的ZIF-67在MAO涂层表面均匀生长,与基体具有良好的附着力,这使得MAO/ZIF-67复合涂层具有良好的耐蚀性。实验证明,ZIF-67能有效封闭MAO涂层的孔隙,增加腐蚀介质侵入路径的曲折度,显著提高镁合金的耐蚀性。此外,MAO预处理使涂层具有强的附着力,这更有利于ZIF-67密封微孔。本研究对于降低MOF涂层在所有金属基底上的应用限制具有重要意义。

电解液pH值对镁合金表面灌注液体型光滑多孔表面耐腐蚀性能的影响

在AZ31镁合金表面制备灌注液体型光滑多孔表面(SLIPS),从而为镁合金提供腐蚀防护。将粗糙多孔的层状双金属氢氧化物(LDH)作为纳米容器,用以盛放液体润滑液。通过调节电解液的pH值,获得用于构筑SLIPS的最佳LDH膜层。研究不同pH值对SLIPS表面形貌、表面润湿性和电化学行为的影响规律。结果表明,当pH值为10.5时,所制备的MgAl-LDH膜层厚度最大,为3.51μm,其可盛放最多的硅油,质量高达0.22mg/mm^(2),使得该MgAl-LDH膜层所构筑的SLIPS可为镁合金提供最优的腐蚀防护性能,腐蚀电流密度最低,为3.72×10^(-9)A/cm^(2)。另一方面,与超疏水表面相比,无论在电化学测试还是在长期浸泡试验中,SLIPS均可为AZ31镁合金基体提供更好的腐蚀防护。镁合金耐腐蚀性能的提高将进一步促进其在实践中的广泛应用。

FGH96/IN718惯性摩擦焊接头高温拉伸断裂特征

为了实现航空用FGH96和IN718异质高温合金高可靠连接,为航空发动机关键部件安全评价及寿命预测提供基础数据及理论支持,采用扫描电子显微镜、金相显微镜研究了FGH96和IN718异质高温合金惯性摩擦焊接头显微组织形貌、高温拉伸试样断口形貌和断裂位置.结果表明,焊接接头焊缝区FGH96和IN718均为等轴晶粒组织,晶粒尺寸约2μm,焊缝区γ′和δ强化相基本全部溶解,热力影响区FGH96侧晶内γ′基本全部溶解,IN718侧δ强化相发生部分溶解,短棒状形貌消失,组织为粗细晶共存组织.焊接接头650℃高温拉伸试样均断裂在焊缝区,但平均抗拉强度可达1080.8 MPa,基本与IN718母材等强,高温拉伸试样起裂位置均处于试样边缘焊缝区,裂纹产生的原因主要是由于焊缝区γ′和δ强化相基本全部溶解,强化作用消失,性能降低.裂纹产生后沿晶界由焊缝熔合线向试样内部扩展,当裂纹从试样边缘焊缝区四周同时向试样内部扩展时,在轴向拉力作用下形成“平台+凹坑”状断口特征,当裂纹从试样边缘焊缝区局部位置开始向试样内部扩展时,在轴向拉力作用下形成“平台+剪切”状断口特征.

职业教育用数字化搅拌摩擦焊教研设备开发与应用

针对国内焊接职业教育实训设备落后,研究开发了适合教学和科研用的多功能搅拌摩擦焊设备。通过试验发现,在保证轴向压力(0.5 kN)不变的前提下,n/v(转速/焊接速度)数值较小(n/v=6,n/v=4),焊缝焊核区、轴肩影响区与热力影响区三者交界处易出现孔洞类缺陷,当n/v数值提高至8及以上时,焊缝内部无可见缺陷存在,究其原因主要是由于n/v数值较小导致热输入过低,交界区域热塑性铝合金流动性较差造成的;相比于恒位移控制方式,采用恒压力控制方式焊接的焊缝表面光滑平整,飞边量小,且不存在表面缺陷。结果表明,开发的教研设备满足了焊接职业教育的实训,并成功应用于教学和科研工作。

Vector Approximate Message Passing with Sparse Bayesian Learning for Gaussian Mixture Prior

Compressed sensing(CS)aims for seeking appropriate algorithms to recover a sparse vector from noisy linear observations.Currently,various Bayesian-based algorithms such as sparse Bayesian learning(SBL)and approximate message passing(AMP)based algorithms have been proposed.For SBL,it has accurate performance with robustness while its computational complexity is high due to matrix inversion.For AMP,its performance is guaranteed by the severe restriction of the measurement matrix,which limits its application in solving CS problem.To overcome the drawbacks of the above algorithms,in this paper,we present a low complexity algorithm for the single linear model that incorporates the vector AMP(VAMP)into the SBL structure with expectation maximization(EM).Specifically,we apply the variance auto-tuning into the VAMP to implement the E step in SBL,which decrease the iterations that require to converge compared with VAMP-EM algorithm when using a Gaussian mixture(GM)prior.Simulation results show that the proposed algorithm has better performance with high robustness under various cases of difficult measurement matrices.

Cell atlas of CCl_(4)-induced progressive liver fibrosis reveals stage-specific responses

Chronic liver injury leads to progressive liver fibrosis and ultimately cirrhosis,a major cause of morbidity and mortality worldwide.However,there are currently no effective anti-fibrotic therapies available,especially for latestage patients,which is partly attributed to the major knowledge gap regarding liver cell heterogeneity and cellspecific responses in different fibrosis stages.To reveal the multicellular networks regulating mammalian liver fibrosis from mild to severe phenotypes,we generated a single-nucleus transcriptomic atlas encompassing 49919nuclei corresponding to all main liver cell types at different stages of murine carbon tetrachloride(CCl_(4))-induced progressive liver fibrosis.Integrative analysis distinguished the sequential responses to injury of hepatocytes,hepatic stellate cells and endothelial cells.Moreover,we reconstructed the cell-cell interactions and gene regulatory networks implicated in these processes.These integrative analyses uncovered previously overlooked aspects of hepatocyte proliferation exhaustion and disrupted pericentral metabolic functions,dysfunction for clearance by apoptosis of activated hepatic stellate cells,accumulation of pro-fibrotic signals,and the switch from an anti-angiogenic to a pro-angiogenic program during CCl_(4)-induced progressive liver fibrosis.Our dataset thus constitutes a useful resource for understanding the molecular basis of progressive liver fibrosis using a relevant animal model.

Magnesium-based energy materials: Progress, challenges, and perspectives

Magnesium-based energy materials, which combine promising energy-related functional properties with low cost, environmental compatibility and high availability, have been regarded as fascinating candidates for sustainable energy conversion and storage. In this review,we provide a timely summary on the recent progress in three types of important Mg-based energy materials, based on the fundamental strategies of composition and structure engineering. With regard to Mg-based materials for batteries, we systematically review and analyze different material systems, structure regulation strategies as well as the relevant performance in Mg-ion batteries(MIBs) and Mg-air batteries(MABs), covering cathodes, electrolytes, anodes for MIBs, and anodes for MABs;as to Mg-based hydrogen storage materials, we discuss how catalyst adding, composite, alloying and nanostructuring improve the kinetic and thermodynamic properties of de/hydrogenation reactions, and in particular, the impacts of composition and structure modification on hydrogen absorption/dissociation processes and free energy modification mechanism are focused;regarding Mg-based thermoelectric materials, the relations between composition/structure and electrical/thermal transport properties of Mg_(3)X_(2)(X = Sb, Bi), Mg_(2)X(X = Si, Ge, Sn) and Mg Ag Sb-based materials, together with the representative research progress of each material system, are summarized and discussed. Finally, by pointing out remaining challenges and providing possible solutions, this review aims to shed light on the directions and perspectives for practical applications of magnesium-based energy materials in the future.

In-situ LDHs growth on PEO coatings on AZ31 magnesium alloy for active protection:Roles of PEO composition and conversion solution

In this work,plasma electrolytic oxidation(PEO)coatings were produced on magnesium alloy AZ31 in aluminate,silicate and phosphate-based electrolytes,and followed by hydrothermal treatments in order to synthesis layered double hydroxides(LDHs)based nanocontainers.LDHs synthesis was done in three different growth solutions(deionized water,sodium nitrate and aluminum nitrate containing solution).In frame of this work it was shown,that it was difficult to form LDHs on Si-based PEO coating,due to more stable silicate phases in comparison with aluminate and phosphate phases in respective PEO coatings.The obtained hybrid LDH/PEO coatings were characterized using SEM,EDS and GDOES,and then the corrosion protection was further investigated by EIS.Based on the obtained results,it was confirmed that,the hydrothermal treatments in Al^(3+)containing solution played an important role on overall corrosion resistance for phosphate and silicate-based PEO coatings,but not for Al-based PEO coatings.

AN INFORMATIC APPROACH TO A LONG MEMORY STATIONARY PROCESS

Long memory is an important phenomenon that arises sometimes in the analysis of time series or spatial data.Most of the definitions concerning the long memory of a stationary process are based on the second-order properties of the process.The mutual information between the past and future I_(p−f) of a stationary process represents the information stored in the history of the process which can be used to predict the future.We suggest that a stationary process can be referred to as long memory if its I_(p−f) is infinite.For a stationary process with finite block entropy,I_(p−f) is equal to the excess entropy,which is the summation of redundancies that relate the convergence rate of the conditional(differential)entropy to the entropy rate.Since the definitions of the I_(p−f) and the excess entropy of a stationary process require a very weak moment condition on the distribution of the process,it can be applied to processes whose distributions are without a bounded second moment.A significant property of I_(p−f) is that it is invariant under one-to-one transformation;this enables us to know the I_(p−f) of a stationary process from other processes.For a stationary Gaussian process,the long memory in the sense of mutual information is more strict than that in the sense of covariance.We demonstrate that the I_(p−f) of fractional Gaussian noise is infinite if and only if the Hurst parameter is H∈(1/2,1).

Bioinspired urchin-like murray carbon nanostructure with protection shell for advanced lithium-sulfur batteries

Commercial application of lithium-sulfur(Li-S) batteries is hindered by the insulating nature of sulfur and the dissolution of polysulfides. Here, a bioinspired 3D urchin-like N-doped Murray's carbon nanostructure(N-MCN) with interconnected micro-meso-macroporous structure and a polydopamine protection shell has been designed as an effective sulfur host for high-performance Li-S batteries. The advanced 3D hierarchically porous framework with the characteristics of the generalized Murray's law largely improves electrolyte diffusion, facilitates electrons/ions transfer and provides strong chemisorption for active species, leading to the synergistic structural and chemical confinement of polysulfides. As a result,the obtained P@S/N-MCN electrode with high areal sulfur loading demonstrates high capacity at high current densities after long cycles. This work reveals that following the generalized Murray's law is feasible to design high-performance sulfur cathode materials for potentially practical Li-S battery applications.

非晶二氧化钛超薄纳米片用于稳定的高倍率锂储存

嵌入型金属氧化物由于降低了低电压下锂沉积风险,作为负极材料在可充电锂离子电池中广泛使用。然而,这类电极材料较低的能量密度、功率密度及循环稳定性差限制了其快充的能力。我们设计合成了一种具备良好电化学循环稳定性的非晶二氧化钛纳米片,在500 mA·g^(-1)的电流密度下循环200圈后具有231 mA·h·g^(-1)的比容量,在6 A·g^(-1)的高电流密度下经过1000圈循环后保持了156.7 mA·h·g^(-1)的比容量。非晶二氧化钛纳米片高倍率性能的提升归因于开放的高度各向同性的结构特性,降低了离子迁移能垒,确保了离子可用性,降低了嵌入后材料的体积变化。本研究表明非晶化是一种有望开发具有高倍率性能的传统金属氧化物电极材料的策略。

“Smart”micro/nano container-based self-healing coatings on magnesium alloys:A review

Coating technologies are a commonly used way to protect metals against corrosion.However,with more and more severe service environments of materials,many protective coating systems often are not environmentally friendly or toxic as in the case of chromates.Based on the world’s abundant ideal magnesium(Mg)and its alloy,the smart self-healing anticorrosive coating can autonomously restore the damaged part of the coating according to the environmental changes,strengthen the corrosion protection ability,and prolong its service life.This paper reviews the research progress of smart self-healing coatings on Mg alloys.These coatings mostly contain suitable corrosion inhibitors encapsulated into micro/nano containers.Moreover,the different self-healing mechanisms and functionalities of micro/nano containers are discussed.The micro/nano containers range from inorganic nanocontainers such as mesoporous nanoparticles(silica(SiO_(2)),titanium dioxide(TiO_(2)),etc.),over inorganic clays(halloysite,hydrotalcite-like,zeolite),to organic nanocontainers such as polymer microcapsules,nanofibers,chitosan(CS)and cyclodextrin(CD),as well as,carbon materials such as graphene and carbon nanotubes and hybrids such as metal organic frameworks.The functioning of micro/nano containers can be divided in two principal groups:autonomous(based on defect filling and corrosion inhibition)and non-autonomous(based on dynamic bonds and shape memory polymers).Moreover,multi functionalities and composite applications of various micro/nano containers are summarized.At present,significant progress has been made in the preparation methods and technologies of micro/nano containers.Achieving long-term self-healing properties of coatings sensing of coating failure and early warning after self-healing function failure can be expected as the main development direction of self-healing corrosion protection coatings in the future.

Metallic few-layered 1T-VS_(2)nanosheets for enhanced sodium storage

Metallic few-layered 1T phase vanadium disulfide nanosheets have been employed for boosting sodium ion batteries.It can deliver a capacity of 241 mAh∙g^(−1)at 100 mA∙g^(−1)after 200 cycles.Such long-term stability is attributed to the facile ion diffusion and electron transport resulting from the well-designed two-dimensional(2D)electron-electron correlations among V atoms in the 1T phase and optimized in-planar electric transport.Our results highlight the phase engineering into electrode design for energy storage.

含血管内皮生长因子缓释微粒显微缝线促进大鼠小血管吻合后的内皮再生

背景:血管内皮生长因子具有成血管作用,目前国内构建血管内皮生长因子缓释微粒缝线预防血管吻合术后并发症方面的报道较少。目的:合成含血管内皮生长因子的缓释微粒缝线,评估其对大鼠小血管吻合后血管再生的作用。方法:采用乳化分散法制备包裹血管内皮生长因子的可生物降解高分子聚乳酸/乙醇酸共聚物微粒,将其负载于显微缝线中,制备含血管内皮生长因子缓释微粒显微缝线。取90只SD大鼠,制作尾动脉血管吻合模型,随机分2组,实验组采用含血管内皮生长因子缓释微粒显微缝线进行吻合,对照组采用普通显微缝线进行吻合,吻合后2 h、12 h、1 d、3 d、7 d,观察两组并发症发生情况、外周血血管内皮生长因子水平及血管吻合处苏木精-伊红染色结果。结果与结论:(1)并发症情况:实验组术后皮肤坏死发生率明显小于对照组(P<0.05);(2)血管内皮生长因子水平:实验组术后不同时间点的外周血血管内皮生长因子水平均高于对照组(P<0.05);(3)苏木精-伊红染色:实验组血管吻合后1 d,吻合口缝线附近可见增生的内皮细胞;吻合后3 d,小血管吻合口两端缝线附近可见大量增生的内皮细胞和内皮下组织,完成覆盖缝线;吻合后1周,内皮细胞及内弹性膜修复完全,平滑肌细胞进一步增生,外膜恢复正常。对照组血管吻合后1 d,吻合口缝线附近表现为创伤后细胞变性坏死,仅外膜层细胞浸润并呈创伤性增生反应;吻合后3 d,内皮细胞脱落区出现新生内皮细胞,并出现生长移行,吻合口开始有少量内皮细胞覆盖;吻合后5-7 d,新生的内皮细胞爬过吻合口裂隙并覆盖缝线;(4)结果表明:含血管内皮生长因子缓释微粒显微缝线可促进大鼠小血管吻合内皮的再生。

PK-15细胞微载体悬浮培养及PCV2增殖工艺研究

研究表明,PCV2仅在PK15等少数哺乳动物细胞上增殖,但由于PCV2毒力弱,且不产生细胞病变,获得高滴度病毒难度较大[1]。因此,PCV2的培养滴度高低已成为制约现有疫苗质量的关键瓶颈之一。为建立在生物反应器内微载体逐级放大培养PK-15细胞和增殖PCV2技术,本研究以德国Sartorius14L生物反应器微载体悬浮培养PK-15细胞,对PK-15细胞初始接种密度、搅拌转速、微载体浓度、PCV2接毒时间、接毒剂量、收毒时间等工艺参数进行了摸索和优化[2-3]。结果表明:3g/L的微载体和60r/min的搅拌转速下,采用0.5×106cells/mL的初始接种密度操作工艺可获得最佳PK-15细胞生长效能。细胞生长后6h接毒,采用感染复数(MOI)为0.5的接毒比例,细胞接毒后在微载体上生长96h可获得最高的PCV2增殖滴度108.5TCID50/mL,利用该工艺,经过消化转移将PK-15细胞从14L反应器放大至42L反应器,微载体上细胞贴附均匀、生长旺盛,42L反应器中培养72h细胞密度可达39.0×105cells/mL,病毒滴度108.3TCID50/mL,应用生物反应器培养PCV2滴度较常规转瓶培养工艺提高了近10倍。进一步表明PCV2悬浮培养放大与接毒工艺稳定,为下一步实现工业级规模化生产奠定基础。

一种新的基于类内不平衡数据学习支持向量机算法

本文以不平衡支持向量机算法为基础,有效应用以往样本集中类内结构信息数据,重点对不平衡数据集进行研究和分析,并提出新的不平衡支持向量机算法,新的算法以类内离散度为基础,仿真实验数据结果证明,经过改进的算法非常有效,可进一步提升G-means值和SE值。