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 …

I and i

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。

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

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

The Theory of Island Biogeography

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.

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

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.

https://science.sciencemag.org/content/sci/277/5330/1232.full.pdf

Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites

Many liquid metals exposed to air develop an oxide film on their outer surface. This film is sufficiently solid-like to provide mechanical stability to small liquid metal droplets, yet weak enough to allow the droplets to be malleable. These properties are useful in both micro-electronics and microfluidics; however, little is known about how to characterize them. Here we probe the elastic, yielding, and relaxation properties of oxide-coated gallium and eutectic gallium indium using a rheometer equipped with a parallel-plate geometry. By using parallel plates of different size, we show that surface stresses dominate bulk stresses. These experiments also demonstrate that the apparent elastic properties of the oxide film are highly sensitive to its strain history. Moreover, the apparent elasticity is sensitive to the stresses stored in the oxide skin. We probe these stresses and their time-dependence, with both torque and normal force measurements. We also characterize the time-dependence of the elasticity b...

/pdf/viscoelastic-properties-of-oxide-coated-liquid-metals-rctot6alsu.pdf

Viscoelastic properties of oxide-coated liquid metals

This paper describes a convenient methodology for the generation of patterned structures on the surface of a self-assembled monolayer (SAM) of alkanethiolates on Au and Ag that combines microcontact printing ( μCP)1 and chemical reaction. 2 A number of reports have described syntheses of patterned structures on preformed SAMs using chemical methods: These methods have typically used either a photochemical pattern transfer step to produce micrometer-scale patterns 3-5 or atomic force microscopy (AFM) to generate patterns at the nanometer scale. 6,7 These methods require alkanethiols that can be inconvenient to synthesize and are often not compatible with complex or sensitive organic groups. In addition, photochemical methods and AFM methods are difficult to use over large areas and on curved substrates. Microcontact printing ( μCP) of alkanethiolates on Au and Ag is a general technique for patterning SAMs over large areas and on curved surfaces. 1 This method is compatible with a wide range of organic functionalities but does require separate synthesis of each thiol that is to be patterned. Here, we demonstrate a new method to pattern SAMs that extends and simplifies conventional μCP and several applications of this method, including the synthesis of a patterned SAM on Au with regions presenting thiol groups: This type of patterned surface cannot be readily obtained using conventional μCP. We have used this surface to pattern the deposition of Au nanoparticles. Figure 1 depicts this method. A reactive SAM presenting interchain carboxylic anhydrides was prepared using the procedure described previously. 2 A poly(dimethylsiloxane) (PDMS) stamp with protruding features (squares ∼10μm on a side) on its surface was inked withn-hexadecylamine and placed in contact with the substrate for 1 min. The anhydride groups in the regions that contacted the stamp reacted with amines and produced a mixed SAM comprising a∼1:1 mixture ofN-alkyl amides and carboxylic acids. 8 The remaining anhydride groups in the uncontacted regions were allowed to react with another amine, CF3(CF2)6CH2NH2, to give a patterned SAM having regions presentingN-hexadecyl amides and fluorinated N-alkyl amides. 9

Patterning a Preformed, Reactive SAM Using Microcontact Printing

The art of Building Small.

This paper demonstrates the use of microlens projection lithography using gray-scale masks to fabricate arrays of microstructures in photoresist In microlens projection lithography, an array of microlenses (diameter d = 1−1000 μm) reduces a common, centimeter-scale pattern in an illuminated mask to a corresponding pattern of micrometer-scale images in its image plane The pattern of intensity projected by the array of microlenses depends on the shape and gray-level distribution of the pattern on the illuminated mask and on the shape and pattern of the lenses The distribution of intensity in the microimages could be adjusted using gray-scale masks After the recording of this intensity distribution in layers of photoresist and developing, the developed resist showed arrays of 3D microstructures over areas larger than 10 cm2 We used these arrays of 3D microstructures as masters and cast transparent elastomer onto them to generate complementary replicas For a specific microlens array and a fixed light so

Fabrication of Arrays of Microlenses with Controlled Profiles Using Gray-Scale Microlens Projection Photolithography

The present invention generally relates to systems and methods of forming particles and, in certain aspects, to systems and methods of forming particles that are substantially monodisperse. Microfluidic systems and techniques for forming such particles are provided, for instance, particles may be formed using gellation, solidification, and/or chemical reactions such as cross-linking, polymerization, and/or interfacial polymerization reactions. In one aspect, the present invention is directed to a plurality of particles having an average dimension of less than about 500 micrometers and a distribution of dimensions such that no more than about 5% of the particles have a dimension greater than about 10% of the average dimension, which can be made via microfluidic systems. In one set of embodiments, at least some of the particles may comprise a metal, and in certain embodiments, at least some of the particles may comprise a magnetizable material. In another set of embodiments, at least some of the particles may be porous. In some embodiments, the invention includes non-spherical particles. Non-spherical particles may be formed, for example, by urging a fluidic droplet into a channel having a smallest dimension that is smaller than the diameter of a perfect mathematical sphere having a volume of the droplet, and solidifying the droplet, and/or by exposing at least a portion of a plurality of particles to an agent able to remove at least a portion of the particles.

George M. Whitesides

Papers

Viscoelastic properties of oxide-coated liquid metals

Patterning a Preformed, Reactive SAM Using Microcontact Printing

The art of Building Small.

Fabrication of Arrays of Microlenses with Controlled Profiles Using Gray-Scale Microlens Projection Photolithography

Systems and methods of forming particles