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

Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

The Chemistry and Applications of Metal-Organic Frameworks

BACKGROUND With a rising global population, increasing energy demands, and impending climate change, major concerns have been raised over the security of our energy future. Developing sustainable, fossil-free pathways to produce fuels and chemicals of global importance could play a major role in reducing carbon dioxide emissions while providing the feedstocks needed to make the products we use on a daily basis. One prospective goal is to develop electrochemical conversion processes that can convert molecules in the atmosphere (e.g., water, carbon dioxide, and nitrogen) into higher-value products (e.g., hydrogen, hydrocarbons, oxygenates, and ammonia) by coupling to renewable energy. Electrocatalysts play a key role in these energy conversion technologies because they increase the rate, efficiency, and selectivity of the chemical transformations involved. Today’s electrocatalysts, however, are inadequate. The grand challenge is to develop advanced electrocatalysts with the enhanced performance needed to enable widespread penetration of clean energy technologies. ADVANCES Over the past decade, substantial progress has been made in understanding several key electrochemical transformations, particularly those that involve water, hydrogen, and oxygen. The combination of theoretical and experimental studies working in concert has proven to be a successful strategy in this respect, yielding a framework to understand catalytic trends that can ultimately provide rational guidance toward the development of improved catalysts. Catalyst design strategies that aim to increase the number of active sites and/or increase the intrinsic activity of each active site have been successfully developed. The field of hydrogen evolution, for example, has seen important breakthroughs over the years in the development of highly active non–precious metal catalysts in acid. Notable advancements have also been made in the design of oxygen reduction and evolution catalysts, although there remains substantial room for improvement. The combination of theory and experiment elucidates the remaining challenges in developing further improved catalysts, often involving scaling relations among reactive intermediates. This understanding serves as an initial platform to design strategies to circumvent technical obstacles, opening up opportunities and approaches to develop higher-performance electrocatalysts for a wide range of reactions. OUTLOOK A systematic framework of combining theory and experiment in electrocatalysis helps to uncover broader governing principles that can be used to understand a wide variety of electrochemical transformations. These principles can be applied to other emerging and promising clean energy reactions, including hydrogen peroxide production, carbon dioxide reduction, and nitrogen reduction, among others. Although current paradigms for catalyst development have been helpful to date, a number of challenges need to be successfully addressed in order to achieve major breakthroughs. One important frontier, for example, is the development of both experimental and computational methods that can rapidly elucidate reaction mechanisms on broad classes of materials and in a wide range of operating conditions (e.g., pH, solvent, electrolyte). Such efforts would build on current frameworks for understanding catalysis to provide the deeper insights needed to fine-tune catalyst properties in an optimal manner. The long-term goal is to continue improving the activity and selectivity of these catalysts in order to realize the prospects of using renewable energy to provide the fuels and chemicals that we need for a sustainable energy future.

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Combining theory and experiment in electrocatalysis: Insights into materials design

Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Water electrolysis driven by renewable resource-derived electricity and direct solar-to-hydrogen conversion based on photochemical and photoelectrochemical water splitting are promising pathways for sustainable hydrogen production. All these techniques require, among many things, highly active noble metal-free hydrogen evolution catalysts to make the water splitting process more energy-efficient and economical. In this review, we highlight the recent research efforts toward the synthesis of noble metal-free electrocatalysts, especially at the nanoscale, and their catalytic properties for the hydrogen evolution reaction (HER). We review several important kinds of heterogeneous non-precious metal electrocatalysts, including metal sulfides, metal selenides, metal carbides, metal nitrides, metal phosphides, and heteroatom-doped nanocarbons. In the discussion, emphasis is given to the synthetic methods of these HER electrocatalysts, the strategies of performance improvement, and the structure/composition-catalytic activity relationship. We also summarize some important examples showing that non-Pt HER electrocatalysts could serve as efficient cocatalysts for promoting direct solar-to-hydrogen conversion in both photochemical and photoelectrochemical water splitting systems, when combined with suitable semiconductor photocatalysts.

Noble metal-free hydrogen evolution catalysts for water splitting

Provided is a method for producing a catalyst for formate dehydrogenation and bicarbonate hydrogenation, comprising the following steps: adding silica colloid in a polyaniline polymerization step and then carrying out a reaction to form a poly(silica-aniline) composite; carbonizing the poly(silica-aniline) composite in the presence of inert gas; removing silica particles from the poly(silica-aniline) composite to form a polyaniline-based porous carbon support; and immobilizing palladium particles on the polyaniline-based porous carbon support to produce the catalyst.

Catalyst for dehydrogenation reaction of formate and hydrogenation reaction of bicarbonate and method of manufactuirng the same

Chiraler nematischer mesoporöser Kohlenstoff aus selbstaggregierter nanokristalliner Cellulose

Electrocatalytic reduction of CO2 to valuable organic compounds and fuels using energy efficient techniques is presently of great importance. In this work, we show the synthesis of Al2O3-decorated reduced graphene...

Facile Synthesis and Characterization of γ-Al2O3 Loaded on Reduced Graphene Oxide Hybrids for Electrochemical Reduction of CO2

The development of new types of materials such as advanced carbon-based nanostructures also requires the development of new surface sensitive characterization techniques to fully unravel the materials’ structures. With regards to “surface” sensitive materials, low energy electron microscopy can be a very powerful tool for precise study of these sensitive materials, see Figure 1, A. Modern commercial scanning electron microscopes enable imaging and analysis of samples by low energy electrons even at very high magnification.

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Treatment and Observation of Advanced Carbon-based Nanomaterials by Slow Electrons

The present invention relates in one aspect to the discovery of novel mesoporous silica nanoparticles (MSNs) templated around and comprising benzalkonium chloride (BAC). In certain embodiments, the BAC-SiO2 mesoporous nanoparticles are capable of sustained release of BAC under acidic conditions, thereby acting as a long release antimicrobial agent. In other embodiments, the BAC-SiO2 mesoporous nanoparticles can be incorporated into a variety of consumer products as an antimicrobial agent additive, including for example, but not limited to, surgical dressings, bandages, deodorants, soaps, facial cleansers and industrial cleaners.

Tewodros Asefa

Papers

Catalyst for dehydrogenation reaction of formate and hydrogenation reaction of bicarbonate and method of manufactuirng the same

Chiraler nematischer mesoporöser Kohlenstoff aus selbstaggregierter nanokristalliner Cellulose

Facile Synthesis and Characterization of γ-Al2O3 Loaded on Reduced Graphene Oxide Hybrids for Electrochemical Reduction of CO2

Treatment and Observation of Advanced Carbon-based Nanomaterials by Slow Electrons

Benzalkonium-Embedded Mesostructured Silica Compositions and Uses of Same