On-chip assay of the effect of topographical microenvironment on cell growth and cell-cell interactions during wound healing

Wound healing is an essential physiological process for tissue homeostasis, involving multiple types of cells, extracellular matrices, and growth factor/chemokine interactions. Many in vitro studies have investigated the interactions between cues mentioned above; however, most of them only focused on a single factor. In the present study, we design a wound healing device to recapitulate in vivo complex microenvironments and heterogeneous cell situations to investigate how three types of physiologically related cells interact with their microenvironments around and with each other during a wound healing process. Briefly, a microfluidic device with a micropillar substrate, where diameter and interspacing can be tuned to mimic the topographical features of the 3D extracellular matrix, was designed to perform positional cell loading on the micropillar substrate, co-culture of three types of physiologically related cells, keratinocytes, dermal fibroblasts, and human umbilical vein endothelial cells, as well as an investigation of their interactions during wound healing. The result showed that cell attachment, morphology, cytoskeleton distribution, and nucleus shape were strongly affected by the micropillars, and these cells showed collaborative response to heal the wound. Taken together, these findings highlight the dynamic relationship between cells and their microenvironments. Also, this reproducible device may facilitate the in vitro investigation of numerous physiological and pathological processes such as cancer metastasis, angiogenesis, and tissue engineering.     

异戊二烯二聚钠系催化剂的制备与研究

在恒温－磁力搅拌实验装置上考察了金属钠负载在不同载体AI2O3分子筛、稀土氧化物（CeO2、La2O3、Sm2O3)和MgO上，在添加剂DIPA／TEA的作用下对异戊二烯二聚的影响，发现酸性载体不利于二聚的形成；稀土氧化物作载体，虽有同类萜类化合物的结构获得，但产率较低；而负载在碱土金属氧化物上，其中碱土中的MgO表现出较好的二聚结果，这也许是与MgO的晶粒细化及载体碱性密切相关，它更有利于金属钠的负载及分散，以提供更多的有效活性中心数目。     

Technology, security, and policy implications of future transatlantic partnerships in space: Lessons from Galileo

Policy makers seek to identify an institutional framework that facilitates the commercialization of publicly funded R&D, while simultaneously addressing innovation market failure. In the space industry, the formation of such a framework is complicated by national security considerations and the fact that numerous sovereign nations are often included in the commercialization process. This paper analyses how multi-public partnerships with industry can promote commercially viable space programs, resolve market failures, and address transatlantic security concerns. The benefits and policy implications of the formation of such transatlantic multi-public-private partnerships (TMP³) are illustrated based on a case study of the design of a major European public-private project in the space industry: the Galileo space-based navigation system.     

Pre-empted patents,infringed patents and firms’ participation in markets for technology

In recent years, firms have increasingly contributed to and been confronted with a patent landscape characterized by numerous but marginal inventions, overlapping claims and patent fences. As a result, firms risk their patent applications to be pre-empted or to be infringed upon by rivals. While both aspects constitute major challenges for the appropriation of returns to inventive activity, extant literature suggests that participation in the market for technology might actually resolve or at least alleviate these problems. In this paper, we investigate the effect of pre-empted and infringed patents on firms’ engagement in in- and cross-licensing. Based on a sample of more than 1100 German manufacturing firms our results show that firms engage in in-licensing as a reaction to pre-empted patents and in cross-licensing if their protected IP was infringed upon. However, these effects vary depending on the fragmentation of technology fields and whether the firm operates in a discrete or complex product industry.     

A numerical study on distributions during cryoprotectant loading caused by laminar flow in a microchannel

In this work, we conduct a computational study on the loading of cryoprotective agents into cells in preparation for cryopreservation. The advantages of microfluidics in cryopreserving cells include control of fluid flow parameters for reliable cryoprotectant loading and reproducible streamlined processing of samples. A 0.25 m long, three inlet T-junction microchannel serves as an idealized environment for this process. The flow field and concentration distribution are determined from a computational fluid dynamics study and cells are tracked as inert particles in a Lagrangian frame. These particles are not confined to streamlines but can migrate laterally due to the Segre-Sildeberg effect for particles in a shear flow. During this tracking, the local concentration field surrounding the cell is monitored. This data are used as input into the Kedem-Katchalsky equations to numerically study passive solute transport across the cell membrane. As a result of the laminar flow, each cell has a unique pathline in the flow field resulting in different residence times and a unique external concentration field along its path. However, in most previous studies, the effect of a spatially varying concentration field on the transport across the cell membrane is ignored. The dynamics of this process are investigated for a population of cells released from the inlet. Using dimensional analysis, we find a governing parameter α, which is the ratio of the time scale for membrane transport to the average residence time in the channel. For α <  = 0.224, cryoprotectant loading is completed to within 5% of the target concentration for all of the cells. However, for α > 0.224, we find the population of cells does not achieve complete loading and there is a distribution of intracellular cryoprotective agent concentration amongst the population. Further increasing α beyond a value of 2 leads to negligible cryoprotectant loading. These simulations on populations of cells may lead to improved microfluidic cryopreservation protocols where more consistent cryoprotective agent loading and freezing can be achieved, thus increasing cell survival.     

Murdered bread, living bread: Doris Grant and the homemade, wholemeal loaf

Doris Grant (1905-2003), a middle-class, British housewife, published numerous books from the 1940s into the 1970s urging her fellow housewives to bake organic, wholemeal bread for their families. This article argues that Grant's arguments defy easy categorization as either 'conservative' or 'progressive'. On the one hand, her targeted appeal to women reflected a traditional, conservative understanding of gender roles: women were, first and foremost, wives and mothers and therefore naturally responsible for family diet and health. On the other hand, Grant also pushed her readers to look beyond their homes and recognize a dangerous food supply system that was impinging on their daily lives. She demanded that her readers reject comfortable complicity in this system and preached the value of individual action in effecting substantive change.     

苏维埃的海归：卡皮查和他的“克里姆林宫书简”

彼得·卡皮查是苏联学术界的领袖人物之一。他早年在英国剑桥大学的卡文迪许实验室从事强肱场和低温物理研究,卓有成就,1929年当选为英国皇家学会会员。1934年他被苏联政府强制留在国内,创建科学院“物理问题研究所”并担任所长,其间发现了液态氦在超低温下具有超流动性,为此获得1984年诺贝尔物理学奖。卡皮查还是一位关心社会,尤其是科学界公共事务的科学家,他向斯大林以及其他苏联最高领导人写了大量书信,为身陷囹圄的科学家陈情,或者对苏联当局的文化和科学政策提出建言,为此本人一度遭到贬斥。     

Preface to Special Topic: Papers from the 82nd American Chemical Society Colloid and Surface Science Symposium, Raleigh, North Carolina, 2008

This Special Topic section of Biomicrofluidics contains original contributions that were presented at the 82nd Colloid and Surface Science Symposium, which took place on 15–18 June 2008 at North Carolina State University. The Symposium covered a wide range of topics that are relevant to the fundamentals of fluidics and their application to biological systems.The recent interest in microfluidics and nanofluidics is constantly increasing due to the numerous applications that these techniques have to offer. They have been used for chemical and biomolecular sensing, separation of charged analytes, and single DNA molecule manipulation. These applications were facilitated by the significant increase in the range of advanced microfabrication and nanofabrication techniques. Improving and extending the range of applicability of micro- and nanofluidic techniques also requires better fundamental understanding of the physics of the transport at small length scales. The transport of fluids and solutes in microchannels and nanochannels usually occurs at very small Reynolds regime. The typical length scale and the surface forces (electrostatic, van der Waals, hydrophobic, hydration, etc.) may be comparable to the size of the channels. All these features often require the development of new experimental techniques and approaches for theoretical analysis.The importance and the substantial recent interest in micro- and nanofluidics prompted the organization of a special session on Electrokinetic Phenomena and Microfluidics as part of the program at the 82nd Colloid and Surface Science Symposium at North Carolina State University in June 2008. The collected papers in this issue of Biomicrofluidics cover some of the very important fundamental and engineering aspects of electrokinetic phenomena in micro- and nanofluidic channels. These include molecular dynamics simulation of biomolecules in confined spaces, analysis of the electric double layer effects on the fluid flow in nanochannels, hydrodynamic resistance to droplet motion in microchannels, electrophoresis in nanocomposite gels, and microfluidics for nanoparticle fabrication. The paper by Srivastava et al.¹ explores the possibility of using microfluidics for fabrication of Janus nanofibers. Chang² presented a theoretical analysis of the electro-osmosis on a salt-free microchannel by simultaneously solving the nonlinear Poisson–Boltzmann equation for the electrostatic potential distribution and the Navier–Stokes equations for the fluid flow. Trahan and Doyle³ reported theoretical analysis of DNA molecule interaction with obstacles in a microchannel. Finally, Labrot et al.⁴ presented studies on the droplet hydrodynamic resistance in a microfluidic channel.We hope that the reader will find the papers useful and informative.     

An integrated dielectrophoretic chip for continuous bioparticle filtering, focusing, sorting, trapping, and detecting

Multi-target pathogen detection using heterogeneous medical samples require continuous filtering, sorting, and trapping of debris, bioparticles, and immunocolloids within a diagnostic chip. We present an integrated AC dielectrophoretic (DEP) microfluidic platform based on planar electrodes that form three-dimensional (3D) DEP gates. This platform can continuously perform these tasks with a throughput of 3 μL∕min. Mixtures of latex particles, Escherichia coli Nissle, Lactobacillus, and Candida albicans are sorted and concentrated by these 3D DEP gates. Surface enhanced Raman scattering is used as an on-chip detection method on the concentrated bacteria. A processing rate of 500 bacteria was estimated when 100 μl of a heterogeneous colony of 10⁷ colony forming units ∕ml was processed in a single pass within 30 min.     

Electro-mechanically controlled assembly of reconfigurable 3D mesostructures and electronic devices based on dielectric elastomer platforms

The manufacture of 3D mesostructures is receiving rapidly increasing attention, because of the fundamental significance and practical applications across wide-ranging areas. The recently developed approach of buckling-guided assembly allows deterministic formation of complex 3D mesostructures in a broad set of functional materials, with feature sizes spanning nanoscale to centimeter-scale. Previous studies mostly exploited mechanically controlled assembly platforms using elastomer substrates, which limits the capabilities to achieve on-demand local assembly, and to reshape assembled mesostructures into distinct 3D configurations. This work introduces a set of design concepts and assembly strategies to utilize dielectric elastomer actuators as powerful platforms for the electro-mechanically controlled 3D assembly. Capabilities of sequential, local loading with desired strain distributions allow access to precisely tailored 3D mesostructures that can be reshaped into distinct geometries, as demonstrated by experimental and theoretical studies of ∼30 examples. A reconfigurable inductive–capacitive radio-frequency circuit consisting of morphable 3D capacitors serves as an application example.     

Fabrication of long poly(dimethyl siloxane) nanochannels by replicating protein deposit from confined solution evaporation

A relatively simple, inexpensive and reliable technique was developed to fabricate an array of nanochannels. Moreover, the nanochannels are directly integrated to microchannels as a whole, which facilitates solution loading from the millimeter-scaled loading reservoirs into the nanochannels. It is found that continuous bovine serum albumin (BSA) line structures with triangle-like cross section at nanoscale can be obtained by evaporation of BSA solution with concentration between 0.5 wt. % and 1 wt. % inside the microchannels. The poly(dimethyl siloxane) nanochannels were replicated from these line structures, followed by sealing with the glass slide. The DNA molecules can be stretched inside the nanochannels as fabricated.     

Urinary calcium excretion and its response to oral calcium loading in normal subjects and stone formers

Ten normal subjects (NS) and 28 stone formers (SF) underwent 1 and 2 gm. calcium loading test following three days of calcium restricted diet (400 mg/day). On 4th day first 24-hr. urine sample was collected. An additional 1 and 2 gm. of calcium (Calcium gluconate) was given orally on 5th and 6th day respectively and 24-hr. urine samples were collected on both the days. Before loading, all the NS had normal calcium excretion (<200 mg/day). Calcium loading caused hypercalciuria in 10% and 20% cases respectively. Among SF, 17.9% cases were already hypercalciuric and calcium loading increased it to 42.9% and 46.4% patients respectively. The results indicated that exogenous calcium had only limited capacity to increase urinary calcium and that the magnitude of rise was relatively higher in SF. The increased excretion in SF was primarily due to intestinal hyperabsorption of calcium.     

镍基单晶平板缺口有限元分析

基于晶体塑性理论并利用有限元方法对镍基单晶含缺口平板的应力应变场进行了分析,研究了外载荷、厚度和缺口半径等对平板缺口部分的等效应力、最大分切应力和应变的影响。结果表明:外载荷的变化不会影响三变量的分布规律,各变量随载荷的增加都呈增大的趋势;厚度和缺口半径是影响缺口尖端应力应变状态的两个重要因素,厚度增大和缺口半径减小都会增加缺口尖端的应力应变集中程度,且应力最大值位置不随厚度发生变化,但随缺口半径的减少其位置也随之向远离缺口尖端方向移动。最后从理论上对缺口的应力应变进行了推导,其结论与有限元分析结果基本相符。     

贵州早泥盆世刺镰蕨的新观察

 刺镰蕨在早泥盆世是一种广布于世界的植物，尽管报道自许多地点，但远未完全地了解它，其主要原因是能育材料罕见。我们观察的标本采自贵州早泥盆世的丹林组。它显示具柄的孢子囊侧生于靠近叶腋的轴上，我们的标本近似球形的孢子囊和它的形态略小于雷诺的肾形孢子囊外，其它方面如：带状的营养轴上具有疏螺旋排列的镰刀状叶，具短柄的孢子囊侧生于轴上以及管胞具穿孔壁等性状与雷诺修订后的刺镰蕨完全一致。我们同意雷诺的观点，将镰蕨目升为纲，与工蕨纲和石松纲并列。它的系统位置是介于工蕨纲和石松纲之间。其下包含一目、一科三个属——镰蕨属、巴拉格瓦纳彻属和星木属。这种植物的生殖部分在中国尚属首次报道。     

新发和烈性传染病的防控与生物安全

近几十年来,SARS冠状病毒、埃博拉病毒、高致病性禽流感H7N9等新发和烈性传染病接连出现,严重影响人类健康。新发和烈性传染病病原由于没有有效的疫苗和药物,具有传染性强、传播速度快、传播范围广等特点,现代生物学技术的发展使得这些病原有可能作为生物武器,威胁我国生物安全。文章分析国内外新发和烈性传染病流行现状,阐述新发和烈性传染病与生物安全的关系以及可能带来的生物恐怖威胁,探讨新发和烈性传染病防控研究的前沿技术,提出了我国新发和烈性传染病防控中存在的问题,同时针对武汉国家生物安全实验室的落成对新发和烈性传染病的防控和生物安全的防护进行了展望。     

Technological innovations and sectoral change: Transformative capacity, adaptability, patterns of change: An analytical framework

Following up on recent debates about sectoral systems of innovation and production, the paper introduces a heuristic framework for analyzing and explaining distinct patterns of technology-based sectoral change. The concept is based on two interrelated influencing factors. The first is the sectoral-specific transformative capacity of new technologies themselves, that is, their substantial or incremental impact on socioeconomic and institutional change in a given sectoral system. The second is the sectoral adaptability of socioeconomic structures, institutions, and actors confronted with the opportunities presented by new technologies. The first factor—the sectoral transformative capacity of new technologies—enables us to identify the technology-based pressure to change and adjust the structural, institutional, and organizational architectures of the sectoral system. The second, complementary factor—sectoral adaptability—helps us to discern the distinct social patterns of anticipating and adopting this technology-based pressure. The specific interplay between the two influencing factors creates distinguishable modes of sectoral transformation, ranging from anticipative and smooth adjustments to reactive and crisis-ridden patterns of change. Even processes of radical sectoral change continue over longer periods of mismatch and are characterized by numerous and mostly gradual organizational, structural and institutional transformations.     

茶树品种分类的探讨

  It is generally accepted that tea plant (Thea sinensis L.) is originated in China, where has numerous varieties,  According to the literature, the selected work of tea plants may be traced as early as to the 3rd-5th century A.D.  The number of varie- ties discovered in recent years reached more than 300.  Besides, a large number of wild species were discovered. In all tea varieties, the crown canopy, leaf size and the date of sprouting were different.  It was proposed that according to the crown canopy, leaf size and the date of sprouting.   The  principle of the classification  of Chinese tea varieties may be 3 orders.  The first order named “group”, it contains macrophanerophyte group, microphanerophyte group, and frutex group.  The second order named “type”, it contains extreme large leaf size, large leaf size, medium leaf size and small leaf size.  The third order named “species”, it contains the early- sprouting species, medium-sprouting species and late-sprouting species.       

Mission and challenges of higher education: an interview with G.Q. Max Lu,the president of the University of Surrey

The University of Surrey (referred to as Surrey hereafter) is one of the renowned universities in the UK that was established on 9 September 1966 with the grant of its Royal Charter and its roots go back to Battersea Polytechnic Institute, founded in 1891. Surrey is the research hub of small satellites, mobile telecommunication and artificial intelligence in Europe. In 2016, Surrey was named as ‘University of the Year’ in the UK and, in February 2018, Surrey won the Queen''s Anniversary Prize for Higher and Further Education (Surrey''s fourth award)—the highest national award for the UK universities, in recognition of the outstanding contribution of Surrey to nutrition and health.The president and vice chancellor of Surrey, Professor Max Lu, took this position in 2016 and is also the first scholar of Chinese origin to be the leader of a British university. Before he joined Surrey, he was the provost and senior vice president at the University of Queensland in Australia. Professor Lu is not only a talented leader in education field, but also a distinguished scientist in materials chemistry and nanotechnology area. He has been honored with numerous awards, including the Orica Award, RK Murphy Medal, China International Science and Technology Award and Medal of the Order of Australia, etc. He has been also appointed to the Prime Minister''s Council for Science and Technology and the Board of UK Research and Innovation, etc. The rich experience and open-mindedness lead to his profound insights into higher education around the world. Lately elected as a fellow of Royal Academy of Engineering (RAEng) and foreign member of the Chinese Academy of Sciences, Professor Lu shared his broad and deep perspectives on higher education with National Science Review during his travel in Beijing.     

零散货物装载的一种快速算法

研究了零散货物的装载问题。根据待装货物体积、重量与货车客积、载重的相对关系，将货物分为两类。对于不同货物类型的单车装载问题，优先考虑其主要约束目标，而对其他目标则适时调整。对于货物足够多的多车装载问题，关键是按照货物的类型确定不同的装车顺序。对于货车足够多的多车装载问题，则利用上次循环得到的解，对下一次的装车次序进行调整，使解不断趋于优化。