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

Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

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

Silver nanoparticles as a new generation of antimicrobials.

Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13

In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28

Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37



Figure 1

Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.



In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.

/pdf/gold-nanoparticles-in-chemical-and-biological-sensing-5e2qojkdzn.pdf

Gold nanoparticles in chemical and biological sensing.

Two-dimensional nanostructures with atomically precise building blocks have potential applications in catalysis and sensing. However, structural instability and surface reactivity limit their practical use. In this work, we demonstrate the formation of vertically aligned nanoplates of the [Co6S8DPPE6Cl6] cluster (Co6 in short), protected by 1,2-bis(diphenylphosphino)ethane, using ambient electrospray deposition (ESD). Charged microdroplets of Co6 formed by ESD on a water surface created such nanostructures. Preferential arrangement of clusters in the nanoplates with enhanced surface area results in sensitive and selective electrochemical response toward arsenite down to 5 parts per billion, in tap water. Density functional theory calculations reveal the preferential binding of arsenite with Co6. Our work points to a practical application of atomically precise clusters of large societal relevance. 

Vertically Aligned Nanoplates of Atomically Precise Co<sub>6</sub>S<sub>8</sub> Cluster for Practical Arsenic Sensing

India has emerged as a leading player in the field of nanoscience and nanotechnology over the last decade. The Indian nano-endeavor got its initial push through the Nano Science and Nano Technology (NS&NT) initiative (now the Nano Mission) of the Department of Science and Technology (DST), Government of India in 2002 and has accelerated very fast since then. This article is intended to sketch a brief picture of the recent nanoscience and technology activities in India with special emphasis on synthesis of nanomaterials and emergence of new properties in them. Application of nanomateials into the very basic needs of India like water purification and energy creation along with the recent developments at the bio-nano interface will be discussed. State of nanoscience education at educational institutions in India and nanoscience based industrial initiatives will be touched upon.

Nanoscience in India: a perspective

Reply to the comment on ‘TenS4+ (n = 1–4) clusters in the gas phase’ by Z. Špalt, M. Alberti, and J. Havel

The chemistry of a new class of molecular clusters having closed cage structure, called metallocarbohedrenes or 
metcars, is described. These molecules of general formula M8C12, where M is a metal, were discovered in mass spectrometry experiments. By reacting laser-evaporated metal with hydrocarbons and cooling the reacton mixture in an inert atmosphere of helium, a number of metcar ions containing Ti, V, Hf, Zr, Mo, Cr and F e have been produced by different workers. The chemistry of these ions is gradually unfolding with several groups putting efforts in experimental and theoretical studies.

Metallocarbohedrenes: A New Class of Molecular Clusters with Cage Structure

L'invention concerne une composition adsorbante comprenant une enveloppe a nano-echelle d'oxyde metallique ou d'hydroxyde sur une nanoarchitecture de bœhmite a matricage organique (OTBN). L'enveloppe a nano-echelle est preparee par impregnation d'OTBN avec un ion metallique ou non-metallique, suivi d'une hydrolyse in situ du ion depose sur la surface d'OTBN. L'epaisseur de l'enveloppe est inferieure a environ 3 nm, ce qui est inferieur a la taille du noyau OTBN. Le nombre de couches d'enveloppe est flexible, formant ainsi une composition hybride a multiples couches a nano-echelle. La composition adsorbante permet d'eliminer des anions inorganiques tels que le fluorure dans l'eau, avec une capacite d'adsorption amelioree.

Thalappil Pradeep

Papers

Vertically Aligned Nanoplates of Atomically Precise Co<sub>6</sub>S<sub>8</sub> Cluster for Practical Arsenic Sensing

Nanoscience in India: a perspective

Reply to the comment on ‘TenS4+ (n = 1–4) clusters in the gas phase’ by Z. Špalt, M. Alberti, and J. Havel

Metallocarbohedrenes: A New Class of Molecular Clusters with Cage Structure

Nanoarchitecture de bœhmite à matriçage organique multicouche destiné à la purification d'eau