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.

Self-assembly of an operating electrical circuit based on shape complementarity and the hydrophobic effect.

Abstract: 470 Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 1998 0935-9648/98/0604-0470 $ 17.50+.50/0 Adv. Mater. 1998, 10, No. 6 FTIR (KBr): n = 2245, 2180, 2115, and 1024 cm. 13 C CP MAS NMR (resonance frequence 100.61 MHz, spining rate 12 kHz): d = 80.6, 69.4, 64.6, 56.7, 52.4, 26.3 and 10.9. Elemental analysis: calcd for ZrC12H18O4: Zr 28.75, C 45.39, H 5.67, O 20.19; found: Zr 33.50, C 41.35, H 5.35. Ta(OEt)5 and Ti(O Pr)4: Prepared similarly using 3 (7.54 mmol, 0.83 g) and a mixture of Ta(OEt)5 (3.89 mmol, 1.58 g) and Ti(O Pr)4 (3.37 mmol, 0.96 g), and isolated as a light brown powder (3.23 g). FTIR (KBr): n = 2245, 2180, 2124, and 1028 cm. C CP MAS NMR (resonance frequency 100.61 MHz, spinning rate 12 kHz): d = 78.9, 69.5, 60.7, 50.7, 26.0, and 19.5. Elemental analysis: calcd for TiTaC24H37O9: Ti 6.86, Ta 25.94, C 41.31, H 5.30, O 20.59; found: Ti 6.80, Ta 24.30, C 41.02, H 4.97. Preparation of 5: {Co2(CO)6}2(m2,h:m2,h-HOCH2±C oC±C oC±CH2 OH) 4 was prepared as described in [13]. 4 (0.53 g, 0.78 mmol) was reacted with Ti(OPr)4 (0.23 g, 0.8 mmol) following the procedure described above. 5 was isolated as a deep-brown solid (0.76 g). FTIR (KBr): n = 2102, 2083, 2061, 2027 cm. Elemental analysis: calcd for TiCo4C24H18O18: Ti 5.45, Co 26.85, H 2.07; found: Ti 6.20, Co 29.40, H 2.10.

Measuring Binding of Protein to Gel-Bound Ligands Using Magnetic Levitation

Abstract: This paper describes the use of magnetic levitation (MagLev) to measure the association of proteins and ligands. The method starts with diamagnetic gel beads that are functionalized covalently with small molecules (putative ligands). Binding of protein to the ligands within the bead causes a change in the density of the bead. When these beads are suspended in a paramagnetic aqueous buffer and placed between the poles of two NbFeB magnets with like poles facing, the changes in the density of the bead on binding of protein result in changes in the levitation height of the bead that can be used to quantify the amount of protein bound. This paper uses a reaction-diffusion model to examine the physical principles that determine the values of rate and equilibrium constants measured by this system, using the well-defined model system of carbonic anhydrase and aryl sulfonamides. By tuning the experimental protocol, the method is capable of quantifying either the concentration of protein in a solution, or the binding affinities of a protein to several resin-bound small molecules simultaneously. Since this method requires no electricity and only a single piece of inexpensive equipment, it may find use in situations where portability and low cost are important, such as in bioanalysis in resource-limited settings, point-of-care diagnosis, veterinary medicine, and plant pathology. It still has several practical disadvantages. Most notably, the method requires relatively long assay times and cannot be applied to large proteins (>70 kDa), including antibodies. The design and synthesis of beads with improved characteristics (e.g., larger pore size) has the potential to resolve these problems.

Fabrication and Replication of Arrays of Single- or Multicomponent Nanostructures by Replica Molding and Mechanical Sectioning

Abstract: This paper describes the fabrication of arrays of nanostructures (rings, crescents, counterfacing split rings, cylinders, coaxial cylinders, and other structures) by a four-step process: (i) molding an array of epoxy posts by soft lithography, (ii) depositing thin films on the posts, (iii) embedding the posts in epoxy, and (iv) sectioning in a plane parallel to the plane defined by the array of posts, into slabs, with an ultramicrotome (“nanoskiving”). This work demonstrates the combination of four capabilities: (i) formation of structures that are submicrometer in all dimensions; (ii) fabrication of 3D structures, and arrays of structures, with gradients of height; (iii) patterning of arrays containing two or more materials, including metals, semiconductors, oxides, and polymers; and (iv) generation of as many as 60 consecutive slabs bearing contiguous arrays of nanostructures. These arrays can be transferred to different substrates, and arrays of gold rings exhibit plasmonic resonances in the range of w...

Practical enzyme-based syntheses of uridine 5'-diphosphogalactose and uridine 5'-diphospho-N-acetylgalactosamine on a gram scale

Abstract: Practical enzyme-based routes for the syntheses of uridine 5'-diphosphogalactose (UDP-Gal) and uridine 5'-diphospho-N-acetylgalactosamine (UDP-GalNAc) on millimole scales have been developed. The activity of galactokinase (EC 2.7.L.6) in crude enzyme extracts from galactose-adapted yeast, coupled to a regenerating system for ATP, provides convenient and economical access to galactose-a-1-phosphate (Gal-1-P) and galactosaminea-l-phosphate (GalN-l-P). The transfer of UMP to the sugar-l-phosphates was also accomplished enzymatically bv Gal-1-P uridyltransferase (EC 2.7.7.12) using uridine 5'-diphosphoglucose (UDP-Glc) as the UMP donor. UDP-Glc was in turn regenerated in situ from glucose-l-phosphate and UTP using UDP-Glc pyrophosphorylase (EC 2.7.7.il. The only chemical step in the sequence was the acetylation of UDP-GaIN to afford UDP-GalNAc using N-acetoxysuccinimide. The moderate overall yields (a3% and34Vo for UDP-Gal and UDP-GalNAc from Gal-l-P and Galll-l-P, respectively) were compensated by the straightforward preparation of the starting materials, UTP and the corresponding sugar-1-P.

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.