George M. Whitesides

Bio: George M. Whitesides is an academic researcher from Harvard University. The author has contributed to research in topics: Microcontact printing & Self-assembled monolayer. The author has an hindex of 240, co-authored 1739 publications receiving 269833 citations. Previous affiliations of George M. Whitesides include University of California, Davis & University of Texas at Austin.

Micromolding in Capillaries: Applications in Materials Science

Abstract: Procedures based on micromolding in capillaries (MIMIC) were used to pattern a surface of a substrate with micrometer- and submicrometer-scale structures. An elastomeric stamp made of poly(dimethylsiloxane) and having relief features in its surface was placed on a substrate; contact between the elastomeric stamp and the substrate formed a network of interconnected channels. A fluida precursor to a polymer, a solution, or a suspension of the material to be patternedfilled these channels by capillary action. After the material in the fluid had cross-linked, crystallized, cured, adhered, or deposited onto the surface of the substrate, the elastomeric component was removed. The microstructures remained on the surface in the pattern complementary to that present in the mold. MIMIC was used to fabricate microstructures of organic polymers, inorganic and organic salts, ceramics, metals, and crystalline microparticles.

Dynamic self-assembly of magnetized, millimetre-sized objects rotating at a liquid–air interface

Abstract: Spontaneous pattern formation by self-assembly is of long-standing and continuing interest not only for its aesthetic appeal, but also for its fundamental and technological relevance. So far, the study of self-organization processes has mainly focused on static structures, but dynamic systems--those that develop order only when dissipating energy--are of particular interest for studying complex behaviour. Here we describe the formation of dynamic patterns of millimetre-sized magnetic disks at a liquid-air interface, subject to a magnetic field produced by a rotating permanent magnet. The disks spin around their axes with angular frequency equal to that of the magnet, and are attracted towards its axis of rotation while repelling each other. This repulsive hydrodynamic interaction is due to fluid motion associated with spinning; the interplay between attractive and repulsive interactions leads to the formation of patterns exhibiting various types of ordering, some of which are entirely new. This versatile system should lead to a better understanding of dynamic self-assembly, while providing a test-bed for stability theories of interacting point vortices and vortex patches.

Integration of paper-based microfluidic devices with commercial electrochemical readers

Abstract: The combination of simple Electrochemical Micro-Paper-based Analytical Devices (EµPADs) with commercially available glucometers allows rapid, quantitative electrochemical analysis of a number of compounds relevant to human health (e.g., glucose, cholesterol, lactate, and alcohol) in blood or urine.

Directional control of lamellipodia extension by constraining cell shape and orienting cell tractional forces

Abstract: Directed cell migration is critical for tissue morphogenesis and wound healing, but the mechanism of directional control is poorly understood. Here we show that the direction in which cells extend their leading edge can be controlled by constraining cell shape using micrometer-sized extracellular matrix (ECM) islands. When cultured on square ECM islands in the presence of motility factors, cells preferentially extended lamellipodia, filopodia, and microspikes from their corners. Square cells reoriented their stress fibers and focal adhesions so that tractional forces were concentrated in these corner regions. When cell tension was dissipated, lamellipodia extension ceased. Mechanical interactions between cells and ECM that modulate cytoskeletal tension may therefore play a key role in the control of directional cell motility.

Oriented Growth of Calcite Controlled by Self-Assembled Monolayers of Functionalized Alkanethiols Supported on Gold and Silver

Abstract: This paper describes the oriented nucleation of calcite controlled by self-assembled monolayers (SAMs) of ω-terminated alkanethiols (HS(CH2)nX) supported on metal films. The effect of the chemistry and geometry of the organic surfaces was surveyed by using different functional groups (X = CO2-, SO3-, PO32-, OH, N(CH3)3+, CH3) and different supporting metals (Au and Ag). Optical microscopy, SEM with image analysis, and XRD were employed to characterize density and orientation of the crystals. Compared to the control surfaces of bare metal films, SAMs terminated in CO2-, SO3-, PO32-, and OH groups were more active in inducing nucleation, whereas SAMs terminated in N(CH3)3+ and CH3 inhibited nucleation. The crystallographic orientations of the crystals were distinct and highly homogeneous for each surface, but different on different surfaces. SAMs of CO2-/Au, CO2-/Ag, OH/Au, OH/Ag, SO3-/Au, and SO3-/Ag induced the face-selective nucleation of calcite from the (015), (012), (104), (103), (1 0 12), and (107) c...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

Large-scale pattern growth of graphene films for stretchable transparent electrodes

Abstract: Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of approximately 280 Omega per square, with approximately 80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm(2) V(-1) s(-1) and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.

Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites

Abstract: Multilayer films of organic compounds on solid surfaces have been studied for more than 60 years because they allow fabrication of multicomposite molecular assemblies of tailored architecture. However, both the Langmuir-Blodgett technique and chemisorption from solution can be used only with certain classes of molecules. An alternative approach—fabrication of multilayers by consecutive adsorption of polyanions and polycations—is far more general and has been extended to other materials such as proteins or colloids. Because polymers are typically flexible molecules, the resulting superlattice architectures are somewhat fuzzy structures, but the absence of crystallinity in these films is expected to be beneficial for many potential applications.