Stereospecific formation of a ternary complex of (S)-α,β-fluoromethylene-dATP with DNA pol β

The influence of water: crystallization of (R/S)-α,β-CHF-dATP with the preorganized pol β-DNA complex shows that (S)-α,β-CHF-dATP is preferentially bound to the active site with the C=F fluorine proximal to a structural water bound to Asp276.     

Quasiharmonic Vibrational Properties of TiNiSn from Ab?Initio Phonons

We report an ab?initio study of vibrational and thermodynamic properties of TiNiSn, a half-Heusler alloy that has been investigated in the context of thermoelectrics, based on density functional theory and density functional perturbation theory. The quasiharmonic approximation, where the Helmholtz free energy obtained from phonons of multiple strained structures is fitted to a model equation of state, is employed to estimate thermodynamic properties. Good quantitative correspondence is achieved between experimental observations and our theoretical calculation for various thermodynamic quantities: lattice parameter, thermal expansion coefficient, and heat capacity. Estimates of lattice thermal conductivity are also provided by using a semianalytic model previously proposed in the literature. Though this yields good qualitative agreement, a more accurate ab?initio approach that explicitly includes anharmonic interactions between atoms should be employed for quantitative predictions of thermal conductivity.     

Asymptotically Optimal Methods of Early Change-Point Detection

Abstract

Based on the excellent review and numerical study presented by Professor T. N. Sriram and Professor R. Iaci, another sequential problem for autoregressive processes is discussed.     

Hardware-efficient technique for minimizing startup transients in Direct Form II digital filters

A technique for generating initial startup conditions for Direct Form II digital filters is presented. Instead of discarding initial samples due to transients, the approach proposed here is to set the initial conditions of the filter so that they represent steady-state conditions of initial step excitation. The paper supplements the existing methods based on the assumptions that the previous input sequence is a white noise or mirrored signal. The approach is presented in both recursive and matrix notations. The performance is investigated in comparison with existing techniques. An illustrative example of image restoration and possible physical implementation is presented.     

Sharp lower bounds on the extractable randomness from non-uniform sources

Extraction of uniform randomness from (noisy) non-uniform sources is an important primitive in many security applications, e.g. (pseudo-)random number generators, privacy-preserving biometrics, and key storage based on Physical Unclonable Functions. Generic extraction methods exist, using universal hash functions. There is a trade-off between the length of the extracted bit string and the uniformity of the string. In the literature there are proven lower bounds on this length as a function of the desired uniformity. The best known bound involves a quantity known as smooth min-entropy. Unfortunately, there exist at least three definitions of smooth entropy. In this paper we compare three of these definitions, and we derive improved lower bounds on the extractable randomness.We also investigate the use of almost universal hash functions, which are slightly worse at extracting randomness than universal hash functions, but are preferable in practice because they require far less resources in devices. We show that using them has negligible effect on the extractable randomness.     

Electrophoretic deposition of carbon nanotubes

Electrophoretic deposition (EPD) has been gaining increasing interest as an economical and versatile processing technique for the production of novel coatings or films of carbon nanotubes (CNTs) on conductive substrates. The purpose of the paper is to present an up-to-date comprehensive overview of current research progress in the field of EPD of CNTs. The paper specifically reviews the preparation and characterisation of stable CNT suspensions, and the mechanism of the EPD process; it includes discussion of pure CNT coatings and CNT/nanoparticle composite films. A complete discussion of the EPD parameters is presented, including electrode materials, deposition time, electrode separation, deposition voltage and resultant electric field. The paper highlights potential applications of the resulting CNT and CNT/composite structures, in areas such as field emission devices, fuel cells, and supercapacitors.     

Supermicroporous alumina–silica zinc oxides

A new family of porous mixed oxides with pores largely in the 8–20 Å range have been prepared. TEOS acts as a solvent and as a source of silica to which aluminum butoxide and transition metal acetates are added. Neutral amines are added as templates and to effect hydrolysis. This paper describes the ZnO–Al₂O₅–SiO₂ system but similar results have been obtained with other transition metal oxides. An interesting feature of the technique is that the larger the amine template the greater is the surface area of the mixed oxide with only a slight increase in the average pore diameter. Both NMR and atomic pair distribution functional methods have been used to prove the homogeneity of the mixed oxide products. This preparative method complements our earlier report in Chemical Communications on mixed oxides prepared with ZrO₂ and TiO₂ incorporating transition metal oxides.     

Synthesis and Functionalization of Fullerenes Encapsulating Atomic Phosphorus

Synthesis, purification, and electron spin properties of the endohedral fullerene P@C₆₀ are reported. Highly enriched material could be obtained for the first time, making this molecule accessible for further experiments. We report the first successful chemical modification of P@C₆₀ via cyclo-propanation to the C_2v symmetric monoadducts P@C₆₁(COOCH₃) and P@C₆₁(COOC₂H₅). X-band electron spin resonance data are presented and discussed. The phosphorus atom shows anisotropic hyperfine coupling in the modified fullerenes, in contrast to the unmodified case, and in contrast to similarly modified N@C₆₀.     

XPS study of duplex stainless steel oxidized by oxygen atoms

Surface oxidation of the duplex stainless steel DSS alloy 2205 was studied by X-ray photoelectron spectroscopy (XPS) and SEM imaging. The experiments were performed on the alloy after controlled oxidation with oxygen atoms created in an inductively coupled plasma. Experiments were performed at temperatures from room temperature up to 700 °C. Compositions of the modified oxidized surfaces were obtained from XPS survey scans, and the chemistries of selected elements from higher energy resolution scans of appropriate peaks. The morphologies of the surfaces were obtained using field emission scanning electron microscopy at different magnifications, up to 10,000×. Different Fe/Cr/Mn oxidized layers and different oxide thicknesses were observed and correlated with temperature.