非晶合金材料发展趋势及启示

金属材料的发展与人类文明和进步息息相关。非晶合金材料是一类原子结构长程无序,具有独特优异性能的新型金属材料。近年来,非晶合金材料的研发、相关科学问题的研究、在高新技术领域的应用得到快速发展,并对金属材料的设计和研发、结构材料、绿色节能材料、磁性材料、催化材料、信息材料等领域产生深刻的影响。为此,文章在回顾非晶合金材料研究和研发历史过程的基础上,分析了当前其学科的前沿科学问题、发展方向,以及我国在该领域发展的问题、机遇和挑战,并提出相应的启示和建议,以期为加快新金属材料的发展,特别是在高新技术领域的应用提供管窥之见。     

Material research from the viewpoint of functional motifs

As early as 2001, the need for the ‘functional motif theory’ was pointed out, to assist the rational design of functional materials. The properties of materials are determined by their functional motifs and how they are arranged in the materials. Uncovering functional motifs and their arrangements is crucial in understanding the properties of materials and rationally designing new materials of desired properties. The functional motifs of materials are the critical microstructural units (e.g. constituent components and building blocks) that play a decisive role in generating certain material functions, and can not be replaced with other structural units without the loss, or significant suppression, of relevant functions. The role of functional motifs and their arrangement in materials, with representative examples, is presented. The microscopic structures of these examples can be classified into six types on a length scale smaller than ∼10 nm with maximum subatomic resolution, i.e. crystal, magnetic, aperiodic, defect, local and electronic structures. Functional motif analysis can be employed in the function-oriented design of materials, as elucidated by taking infrared non-linear optical materials as an example. Machine learning is more efficient in predicting material properties and screening materials with high efficiency than high-throughput experimentation and high-throughput calculations. In order to extract functional motifs and find their quantitative relationships, the development of sufficiently reliable databases for material structures and properties is imperative.     

Nanomechanics of graphene

The super-high strength of single-layer graphene has attracted great interest. In practice, defects resulting from thermodynamics or introduced by fabrication, naturally or artificially, play a pivotal role in the mechanical behaviors of graphene. More importantly, high strength is just one aspect of the magnificent mechanical properties of graphene: its atomic-thin geometry not only leads to ultra-low bending rigidity, but also brings in many other unique properties of graphene in terms of mechanics in contrast to other carbon allotropes, including fullerenes and carbon nanotubes. The out-of-plane deformation is of a ‘soft’ nature, which gives rise to rich morphology and is crucial for morphology control. In this review article, we aim to summarize current theoretical advances in describing the mechanics of defects in graphene and the theory to capture the out-of-plane deformation. The structure–mechanical property relationship in graphene, in terms of its elasticity, strength, bending and wrinkling, with or without the influence of imperfections, is presented.     

Shadow glass transition as a thermodynamic signature of β relaxation in hyper-quenched metallic glasses

One puzzling phenomenon in glass physics is the so-called ‘shadow glass transition’ which is an anomalous heat-absorbing process below the real glass transition and influences glass properties. However, it has yet to be entirely characterized, let alone fundamentally understood. Conventional calorimetry detects it in limited heating rates. Here, with the chip-based fast scanning calorimetry, we study the dynamics of the shadow glass transition over four orders of magnitude in heating rates for 24 different hyper-quenched metallic glasses. We present evidence that the shadow glass transition correlates with the secondary (β) relaxation: (i) The shadow glass transition and the β relaxation follow the same temperature–time dependence, and both merge with the primary relaxation at high temperature. (ii) The shadow glass transition is more obvious in glasses with pronounced β relaxation, and vice versa; their magnitudes are proportional to each other. Our findings suggest that the shadow glass transition signals the thermodynamics of β relaxation in hyper-quenched metallic glasses.     

Regenerated isotropic wood

Construction of sustainable high-performance structural materials is a core part of the key global sustainability goal. Many efforts have been made in this field; however, challenges remain in terms of lowering costs by using all-green basic building blocks and improving mechanical properties to meet the demand of practical applications. Here, we report a robust and efficient bottom-up strategy with micro/nanoscale structure design to regenerate an isotropic wood from natural wood particles as a high-performance sustainable structural material. Regenerated isotropic wood (RGI-wood) exceeds the limitations of the anisotropic and inconsistent mechanical properties of natural wood, having isotropic flexural strength of ∼170 MPa and flexural modulus of ∼10 GPa. RGI-wood also shows superior water resistance and fire retardancy properties to natural pine wood. Mass production of large sized RGI-wood and functional RGI-wood nanocomposites can also be achieved.     

中国环境经济系统的物质需求量研究

本文采用物质流分析方法描述了我国经济系统的资源消耗特征和变化趋势.结果表明：中国物质需求总量已显著超过美国,并且具有快速上升趋势;人均物质消耗量不高,与日本和英国相当;中国环境库兹涅茨曲线的倒“U”型特征显著;出口物质的巨大隐藏流导致当前的对外贸易处于不利地位.     

资源流研究的理论与方法探析

资源流研究是资源科学在新形势下需要重视的新的学术视角，目前国内外的研究比较零散，迄今为止还没有形成一个系统、科学的理论体系。资源流的内涵体现在复杂性、动态性和时空性3个方面。资源流的构成要素包括系统、物质、能量、价值、劳动力等。资源流主要研究资源在进入社会经济系统后的变化规律，阐明资源流动变化过程及其环境和经济效应，揭示资源在社会经济运动中与生态、环境相互作用的机理，为资源高效利用和可持续管理提供科学依据。目前资源流研究所用的方法主要有投入产出分析、物质流分析、工业代谢、生命周期评价等。这些方法来自不同的学科领域，从不同的角度探讨资源流动，具有各自的特点和局限性。未来资源流研究的重点主要有：按部门进行资源流研究、按地域进行资源流研究、战略性资源的流动研究、相关社会价值问题研究以及综合评价方法的研究。     

Deformation properties between fluid and periodic circular obstacles in polydimethylsiloxane microchannels: Experimental and numerical investigations under various conditions

Understanding the mechanical properties of optically transparent polydimethylsiloxane (PDMS) microchannels was essential to the design of polymer-based microdevices. In this experiment, PDMS microchannels were filled with a 100 μM solution of rhodamine 6G dye at very low Reynolds numbers (∼10⁻³). The deformation of PDMS microchannels created by pressure-driven flow was investigated by fluorescence microscopy and quantified the deformation by the linear relationship between dye layer thickness and intensity. A line scan across the channel determined the microchannel deformation at several channel positions. Scaling analysis widely used to justify PDMS bulging approximation was allowed when the applied flow rate was as high as 2.0 μl/min. The three physical parameters (i.e., flow rate, PDMS wall thickness, and mixing ratio) and the design parameter (i.e., channel aspect ratio = channel height/channel width) were considered as critical parameters and provided the different features of pressure distributions within polymer-based microchannel devices. The investigations of the four parameters performed on flexible materials were carried out by comparison of experiment and finite element method (FEM) results. The measured Young''s modulus from PDMS tensile test specimens at various circumstances provided reliable results for the finite element method. A thin channel wall, less cross-linker, high flow rate, and low aspect ratio microchannel were inclined to have a significant PDMS bulging. Among them, various mixing ratios related to material property and aspect ratios were one of the significant factors to determine PDMS bulging properties. The measured deformations were larger than the numerical simulation but were within corresponding values predicted by the finite element method in most cases.     

流阻和摩擦对流体流动作功装置性能的影响

研究非线性流阻和作功机械内部摩擦对流体流动作功装置性能的影响,导出输出功率与机械效率以及功率损耗与机械效率间的关系,又由此导出最大输出功率及其相应的一些重要性能参数,并作些有意义的讨论。所得结论可为流体流动作功装置的优化设计提供些新理论依据。     

Dielectrophoretic capture of low abundance cell population using thick electrodes

Enrichment of rare cell populations such as Circulating Tumor Cells (CTCs) is a critical step before performing analysis. This paper presents a polymeric microfluidic device with integrated thick Carbon-PolyDimethylSiloxane composite (C-PDMS) electrodes designed to carry out dielectrophoretic (DEP) trapping of low abundance biological cells. Such conductive composite material presents advantages over metallic structures. Indeed, as it combines properties of both the matrix and doping particles, C-PDMS allows the easy and fast integration of conductive microstructures using a soft-lithography approach while preserving O₂ plasma bonding properties of PDMS substrate and avoiding a cumbersome alignment procedure. Here, we first performed numerical simulations to demonstrate the advantage of such thick C-PDMS electrodes over a coplanar electrode configuration. It is well established that dielectrophoretic force (F_DEP) decreases quickly as the distance from the electrode surface increases resulting in coplanar configuration to a low trapping efficiency at high flow rate. Here, we showed quantitatively that by using electrodes as thick as a microchannel height, it is possible to extend the DEP force influence in the whole volume of the channel compared to coplanar electrode configuration and maintaining high trapping efficiency while increasing the throughput. This model was then used to numerically optimize a thick C-PDMS electrode configuration in terms of trapping efficiency. Then, optimized microfluidic configurations were fabricated and tested at various flow rates for the trapping of MDA-MB-231 breast cancer cell line. We reached trapping efficiencies of 97% at 20 μl/h and 78.7% at 80 μl/h, for 100 μm thick electrodes. Finally, we applied our device to the separation and localized trapping of CTCs (MDA-MB-231) from a red blood cells sample (concentration ratio of 1:10).     

Novel 2D CaCl crystals with metallicity,room-temperature ferromagnetism,heterojunction, piezoelectricity-like property and monovalent calcium ions

Under ambient conditions, the only known valence state of calcium ions is +2, and the corresponding crystals with calcium ions are insulating and nonferromagnetic. Here, using cryo-electron microscopy, we report direct observation of two-dimensional (2D) CaCl crystals on reduced graphene oxide (rGO) membranes, in which the calcium ions are only monovalent (i.e. +1). Remarkably, metallic rather than insulating properties are displayed by those CaCl crystals. More interestingly, room-temperature ferromagnetism, graphene–CaCl heterojunction, coexistence of piezoelectricity-like property and metallicity, as well as the distinct hydrogen storage and release capability of the CaCl crystals in rGO membranes are experimentally demonstrated. We note that such CaCl crystals are obtained by simply incubating rGO membranes in salt solutions below the saturated concentration, under ambient conditions. Theoretical studies suggest that the formation of those abnormal crystals is attributed to the strong cation-π interactions of the Ca cations with the aromatic rings in the graphene surfaces. The findings highlight the realistic potential applications of such abnormal CaCl material with unusual electronic properties in designing novel transistors and magnetic devices, hydrogen storage, catalyzers, high-performance conducting electrodes and sensors, with a size down to atomic scale.     

Li-ion battery material under high pressure: amorphization and enhanced conductivity of Li4Ti5O12

Lithium titanium oxide (Li₄Ti₅O₁₂, LTO), a ‘zero-strain’ anode material for lithium-ion batteries, exhibits excellent cycling performance. However, its poor conductivity highly limits its applications. Here, the structural stability and conductivity of LTO were studied using in situ high-pressure measurements and first-principles calculations. LTO underwent a pressure-induced amorphization (PIA) at 26.9 GPa. The impedance spectroscopy revealed that the conductivity of LTO improved significantly after amorphization and that the conductivity of decompressed amorphous LTO increased by an order of magnitude compared with its starting phase. Furthermore, our calculations demonstrated that the different compressibility of the LiO₆ and TiO₆ octahedra in the structure was crucial for the PIA. The amorphous phase promotes Li⁺ diffusion and enhances its ionic conductivity by providing defects for ion migration. Our results not only provide an insight into the pressure depended structural properties of a spinel-like material, but also facilitate exploration of the interplay between PIA and conductivity.     

Ultrafast growth of large single crystals of monolayer WS2 and WSe2

Monolayer transition metal dichalcogenides (TMDs) have attracted considerable attention as atomically thin semiconductors for the ultimate transistor scaling. For practical applications in integrated electronics, large monolayer single crystals are essential for ensuring consistent electronic properties and high device yield. The TMDs available today are generally obtained by mechanical exfoliation or chemical vapor deposition (CVD) growth, but are often of mixed layer thickness, limited single crystal domain size or have very slow growth rate. Scalable and rapid growth of large single crystals of monolayer TMDs requires maximization of lateral growth rate while completely suppressing the vertical growth, which represents a fundamental synthetic challenge and has motivated considerable efforts. Herein we report a modified CVD approach with controllable reverse flow for rapid growth of large domain single crystals of monolayer TMDs. With the use of reverse flow to precisely control the chemical vapor supply in the thermal CVD process, we can effectively prevent undesired nucleation before reaching optimum growth temperature and enable rapid nucleation and growth of monolayer TMD single crystals at a high temperature that is difficult to attain with use of a typical thermal CVD process. We show that monolayer single crystals of 450 μm lateral size can be prepared in 10 s, with the highest lateral growth rate up to 45 μm/s. Electronic characterization shows that the resulting monolayer WSe₂ material exhibits excellent electronic properties with carrier mobility up to 90 cm² V⁻¹ s⁻¹, comparable to that of the best exfoliated monolayers. Our study provides a robust pathway for rapid growth of high-quality TMD single crystals.     

基于物质流分析的中国机械行业铁资源代谢过程研究

科学分析金属资源代谢过程和计算金属制品报废量是新时代下推进资源节约和循环利用的关键性问题之一。本文使用了动态物质流与静态物质流相结合的方法、生命周期方法、Weibull分布模型和Minitab软件,计算了1949—2016年中国机械行业铁资源的理论报废量,并对13类机械产品在不同消费结构下的报废量进行动态对比。研究发现：① 1949—2016年中国含铁产品理论报废量为21.20亿t,其中机械行业理论报废量为4.10亿t,实际回收量分别为17.60亿t和2.80亿t;② 机械行业报废回收效率为68.3%,其中农业机械类、石油化工机械类、电工电器机械类和汽车（非交通运输类）等产品的报废量增长显著;③ 2016年铁资源生产阶段中国共投入铁矿石11亿t,经加工阶段后得到7.31亿t粗钢,进入社会终端消费量为6.73亿t,代谢过程资源损失率达38.8%;④ 2016年中国铁产品社会存量为83亿t,预计2025年将进入存量铁制品的快速报废期。未来中国钢铁产业的战略重点应侧重生产阶段的技术创新,以减少资源损失和环境影响,通过供给侧改革提高钢铁二次资源循环利用效率来解决一系列资源环境问题。     

Integrated dynamic wet spinning of core-sheath hydrogel fibers for optical-to-brain/tissue communications

Hydrogel optical light-guides have received substantial interest for applications such as deep-tissue biosensors, optogenetic stimulation and photomedicine due to their biocompatibility, (micro)structure control and tissue-like Young''s modulus. However, despite recent developments, large-scale fabrication with a continuous synthetic methodology, which could produce core-sheath hydrogel fibers with the desired optical and mechanical properties suitable for deep-tissue applications, has yet to be achieved. In this study, we report a versatile concept of integrated light-triggered dynamic wet spinning capable of continuously producing core-sheath hydrogel optical fibers with tunable fiber diameters, and mechanical and optical propagation properties. Furthermore, this concept also exhibited versatility for various kinds of core-sheath functional fibers. The wet spinning synthetic procedure and fabrication process were optimized with the rational design of the core/sheath material interface compatibility [core = poly(ethylene glycol diacrylate-co-acrylamide); sheath = Ca-alginate], optical transparency, refractive index and spinning solution viscosity. The resulting hydrogel optical fibers exhibited desirable low optical attenuation (0.18 ± 0.01 dB cm⁻¹ with 650 nm laser light), excellent biocompatibility and tissue-like Young''s modulus (<2.60 MPa). The optical waveguide hydrogel fibers were successfully employed for deep-tissue cancer therapy and brain optogenetic stimulation, confirming that they could serve as an efficient versatile tool for diverse deep-tissue therapy and brain optogenetic applications.     

中小企业技术创新组织模式优化选择

中小企业技术创新组织模式的基本特征是形态扁平化、规模小型化、性质柔性化和形式网络化。常见缺陷主要有结构缺陷、机制缺陷、动力缺陷和效益缺陷等。中小企业技术创新组织优化选择一方面要求企业选择恰宜的技术创新战略目标和组织原则,另一方面需要企业构建学习型技术创新组织,进一步变革传统的技术创新组织模式。     

The structure and properties of spider silk

Silks from the spider's orb-web are amongst the very best structural materials produced by nature: spiders can produce a large aerial filter from a minimal amount of material. By studying how the structure and properties of silks are matched to their mechanical function, we can increase our general understanding of structure-property relationships in fibrous polymers.     

IT企业知识员工玩趣人格对其创新行为的影响——工作沉浸的中介作用与职业承诺的调节作用

引入中介变量工作沉浸和调节变量职业承诺来探究玩趣人格对创新行为的作用机制.结果表明:知识员工的玩趣人格对其创新行为有显著正向影响;工作沉浸及其专注、工作享受和内在工作动机3个维度在玩趣人格与员工创新行为之间均存在部分中介作用;职业承诺对玩趣人格与工作沉浸间关系起正向调节作用;职业承诺对玩趣人格与工作沉浸的专注及内在工作动机两个维度间的关系起正向调节作用.     

Carbon nanotubes for flexible batteries: recent progress and future perspective

Flexible batteries, which maintain their functions potently under various mechanical deformations, attract increasing interest due to potential applications in emerging portable and wearable electronics. Significant efforts have been devoted to material synthesis and structural designs to realize the mechanical flexibility of various batteries. Carbon nanotubes (CNTs) have a unique one-dimensional (1D) nanostructure and are convenient to further assemble into diverse macroscopic structures, such as 1D fibers, 2D films and 3D sponges/aerogels. Due to their outstanding mechanical and electrical properties, CNTs and CNT-based hybrid materials are superior building blocks for different components in flexible batteries. This review summarizes recent progress on the application of CNTs in developing flexible batteries, from closed-system to open-system batteries, with a focus on different structural designs of CNT-based material systems and their roles in various batteries. We also provide perspectives on the challenges and future research directions for realizing practical applications of CNT-based flexible batteries.     

软件动态流程模型及其形式化描述方法研究

面向服务的体系结构正在促进软件结构研究的发展,特别是对于那些面临需求经常变更的企业过程流程应用系统而言更是如此。为了适应现实需求,本文给出了一个基于粒度等级和松散耦合的动态软件流程(SAWM)模型,利用XML的可扩展性提出了FDL流程描述语言和ADL活动描述语言,结合SAX事件驱动的解释技术实现了流程语义解释和自适应调整,建立了软件动态流程关系。