Rational design of DNA nanoarchitectures

DNA has many physical and chemical properties that make it a powerful material for molecular constructions at the nanometer length scale. In particular, its ability to form duplexes and other secondary structures through predictable nucleotide-sequence-directed hybridization allows for the design of programmable structural motifs which can self-assemble to form large supramolecular arrays, scaffolds, and even mechanical and logical nanodevices. Despite the large variety of structural motifs used as building blocks in the programmed assembly of supramolecular DNA nanoarchitectures, the various modules share underlying principles in terms of the design of their hierarchical configuration and the implemented nucleotide sequences. This Review is intended to provide an overview of this fascinating and rapidly growing field of research from the structural design point of view.     

Computational studies on polymer adhesion at the surface of gamma-Al2O3. I. The adsorption of adhesive component molecules from the gas phase

We calculate the minimum energy paths and reaction energies of the adsorption of the epoxide adhesive components diglycidylesterbisphenol A (DGEBA), diethyltriamine (DETA), and the adhesion promoter 3-aminopropylmethoxysilane (AMEO) at two different sites on a model of the native Al2O3 surface, using the nudged elastic band algorithm in conjunction with self-consistent charge-density functional based tight binding. Our results show that the chosen combination of methods is well suited to obtain an overview of the reaction mechanisms and kinetics of the adsorption of organic molecules on inorganic surfaces. The obtained MEP-s show that there is preference for the adsorption of the adhesion promoter, AMEO, over the resin, DGEBA, while the adsorption of the curing agent, DETA, is unfavorable. Our approach also gives an insight into the ranges of the mechanical and electronic influences of the adsorption process on the interface, which neither full ab initio methods nor force field approaches can provide. These results will help to develop a quantum mechanics-molecular mechanics multiscale embedding scheme for more detailed studies of organic/inorganic hybrid interface reactions.     

Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces

This study examines the hydrodynamics and temperature characteristics of distilled deionized water droplets impinging on smooth and nano-structured surfaces using high speed (HS) and infrared (IR) imaging at We = 23.6 and Re = 1593, both based on initial drop impingement parameters. Results for a smooth and nano-structured surface for a range of surface temperatures are compared. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. The near surface average droplet fluid temperatures are evaluated for conditions of evaporative cooling and boiling. Also included are surface temperature results using a gold layered IR opaque surface on silicon. Four stages of the impingement process are identified: impact, boiling, near constant surface diameter evaporation, and final dry-out. For the boiling conditions there is initial nucleation followed by severe boiling, then near constant diameter evaporation resulting in shrinking of the droplet height. When a critical contact angle is reached during evaporation the droplet rapidly retracts to a smaller diameter reducing the contact area with the surface. This continues as a sequence of retractions until final dry out. The basic trends are the same for all surfaces, but the nano-structured surface has a lower dissipated energy during impact and enhances the heat transfer for evaporative cooling with a 20% shorter time to achieve final dry out.     

Itoh-Tsujii Inversion in Standard Basis and Its Application in Cryptography and Codes

This contribution is concerned with a generalization of Itoh and Tsujii's algorithm for inversion in extension fields . Unlike the original algorithm, the method introduced here uses a standard (or polynomial) basis representation. The inversion method is generalized for standard basis representation and relevant complexity expressions are established, consisting of the number of extension field multiplications and exponentiations. As the main contribution, for three important classes of fields we show that the Frobenius map can be explored to perform the exponentiations required for the inversion algorithm efficiently. As an important consequence, Itoh and Tsujii's inversion method shows almost the same practical complexity for standard basis as for normal basis representation for the field classes considered.     

Magnetic penetration depth of 585-01585-01585-01: Tc ∼ σ0 in the overdoped region

We report transverse field muon spin rotation experiments carried out on Tl₂Ba₂CuO₆₊. This system spans the whole overdoped regime, in which T_c is reduced by excess oxygen doping despite an increasing normal state carrier concentration. In the heavily overdoped regime the extrapolated low temperature depolarization rate(0) is found to scale linearly with the superconducting critical temperature T_c similar to the behavior previously observed for other cuprates in the underdoped regime. In the framework of the clean limit London model,(0) ^–2 n _s (0)/m _s ^* , suggesting that the depression of T_c by overdoping is associated with a decrease of the superconducting condensate density. This needs to be understood in view of the observed increase in the normal state carrier density. We discuss some possible explanations for this behavior.