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.

Microcontact printing of alkanethiols on copper and its application in microfabrication

Abstract: Microcontact printing (μCP)1 is a convenient technique for generating patterned self-assembled monolayers (SAMs)2 of alkanethiolates on gold1 and silver3 and of alkylsiloxanes on silicon dioxide and glass.4,5 Patterned SAMs of hexadecanethiolate on gold and silver can be used directly as ultrathin resists in selective wet etching to fabricate patterned microstructures of these metals with dimensions of >0.2 μm.1,3,6-9 The present study is a natural extension of this technique, since alkanethiols also form organized monolayers on evaporated films of copper.10 The chemical reactivity of coinage metals increases in the order of Au < Ag < Cu; it is possible to find an etchant that dissolves only Cu but not Ag and Au or only Ag but not Au. For example, aqueous FeCl3 solution, an etchant that is widely used in semiconductor industry to produce printed circuits of copper,11 etches silver and gold very slowly or not at all.3 This ability to carry out “orthogonal etching” offers an opportunity to generate junctions of Cu-Ag, Cu-Au, and Ag-Au by using a multistep procedure that includes metal evaporation, microcontact printing with hexadecanethiol, and selective wet etching. Figure 1 shows scanning electron micrographs (SEMs) of copper samples (50 nm thick) that had been patterned with SAMs of hexadecanethiolate and etched in an aqueous FeCl3 solution (0.012 M) for 2-3 s.12 The microparticles (∼0.5 μm in size) on the bare regions of copper are CuCl (shown by energy-dispersed spectroscopy, EDS). They were formed in situ during the dissolution of bare copper:

Affinity capillary electrophoresis can simultaneously measure binding constants of multiple peptides to vancomycin

Abstract: Affnity capillary electrophoresis is a sensitive and convenient technique for studying molecular recognition involving low molecular weight receptors

Substrate specificity and carbohydrate synthesis using transketolase

Abstract: This paper describes the use of the enzyme transketolase as a catalyst in organic synthesis. The properties of transketolase from both yeast and spinach were investigated. The yeast enzyme was found to be more convenient for routine use. Examination of the substrate specificity of yeast transketolase demonstrated that the enzyme accepts a wide variety of 2-hydroxy aldehydes as substrates. A practical protocol for transketolase-catalyzed condensation of hydroxypyruvic acid with these aldehydes has been developed and used for the synthesis of four carbohydrates: L-idose, L-gulose, 2-deoxy-L-xylohexose, an L-xylose

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.