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.

Fibroblasts Enhance Migration of Human Lung Cancer Cells in a Paper-Based Coculture System.

Abstract: A multilayered paper-based platform is used to investigate the interactions between human lung tumor cells and fibroblasts that are isolated from primary patient tumor samples.

Nanostructure fabrication in silicon using cesium to pattern a self-assembled monolayer

Abstract: This letter describes the formation of nanometer-scale features in a silicon substrate using a self-assembled monolayer (SAM) of octylsiloxane on silicon dioxide as a resist sensitive to a patterned beam of neutral cesium atoms. The mask that patterned the atomic beam was a silicon nitride membrane perforated with nm and μm scale holes, in contact with the substrate surface. In a two-step wet-chemical etching process, the pattern formed in the SAM was transferred first into the SiO2 layer and then into an underlying silicon substrate. This process demonstrated the formation of silicon features with diameter ∼60 nm.

Hypercross-Linked Organic Solids: Preparation from Poly(aromatic diacetylenes) and Preliminary Measurements of their Young's Modulus, Hardness, and Thermal Stability

Abstract: We are engaged in a program intended to establish relationships between the microscopic structure of highly cross-linked organic solids and the Young's modulus, thermal stability, and hardness of these solids. This program was stimulated by an interest in the physical properties of diamond.' Diamond is the hardest substance known, is the best thermal conductor, and has the highest known Young's modulus. These properties undoubtedly reflect, in some way, the high volume density of strong, directional carbon-carbon bonds that characterize the structure of diamond. Our objective is to prepare organic solids with a high and controllable density of carbon-carbon bonds, to characterize the bonding in these solids, to establish their physical and materials properties (especially Young's modulus, thermal stability, and hardness), and to correlate their microscopic structures with these macroscopic properties. Our approach has been to prepare organic oligomers containing a high proportion of acetylenic groups capable of forming carbon-carbon bonds, to mold these oligomers into macroscopic objects, and to cause the cross-linking reaction to occur in the solid state (eq 1). It was our OZ, 65 OC 150-3M'C I f (1) CUCI, TMEDA pyridine odlchlorobenzena 1b-5b 1c-5c hypothesis that a high ratio of carbon to hydrogen in these oligomers and, thus, a high density of carbon-carbon bonds in the solids derived from them, would result in a high modulus and thermal stability. This paper summarizes the preparation of polymers from five aromatic di-acetylenes (la-5a)2 and the conversion of these polymers to highly cross-linked solids (lc-54. These structures were chosen to survey the response of the physical properties of the final cross-linked solid to variation in the structure

Determination of enantiomeric purity of polar substrates with chiral lanthanide NMR shift reagents in polar solvents

Abstract: The proton NMR spectra of 19 1,2and l,3-dioxygenated compounds were studied in deuteriated acetonitrile, acetone, and chloroform in the presence of chiral lanthanide NMR shift reagents tris(ll-((heptafluoropropyl)hydroxymethylene)-d-camphorato)europium(III) (1) and tris(((trifluoromethyl)hvdroxymethylene)-d-camphorato)europium(III) (2). Enantiotopic OH, CH, and CH3 NMR resonances were best resolved in acetonitrile; line broadening obscured the scalar coupling. Enantiomeric excesses as high as 98Vo can be determined for 16 of these compounds in this polar solvent.

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.