A vortex model with superfluid and turbulent percolation

Simple lattice vortex models are presented that exhibit vortex percolation along lines in a temperature/chemical potential plane. Parts of these lines can be identified with the percolation threshold at the inertial range of turbulence, and other parts are analogous to the transition in a three-dimensionalXY model that may model the . transition in superfluidity. Flory exponents at percolation are calculated; for nonnegative temperatures, their values approximate the standard Flory value, and are approximately constant along the transition lines, in agreement with recent conjectures. Conclusions regarding coherent structures in turbulence are also reached.     

Solution of lattice models by successive linkage

A linkage algorithm is presented for evaluating the partition function of a union of finite lattice blocks in terms of the partition functions of the component blocks. This algorithm leads to: (i) A fast enumeration method for evaluating the partition function of a finite lattice (for Ising spins in two dimensions, the number of terms needed to evaluate the partition function for a block ofL spins if reduced from 2 ^L to ); (ii) a recursive factorization procedure that accelerates the rate at which quantities evaluated on a finite lattice converge to their thermodynamic limit, and (iii) a scaling procedure that further accelerates the convergence to the thermodynamic limit. The scaling procedure is similar to a method previously used in turbulence calculations.Supported in part by the Applied Mathematics Subprogram of the Office of Energy Research, U.S. Department of Energy, under contract DE-AC03-76SF0098, and in part by the Office of Naval Research under contract N00014-76-C-0316     

Heats of combustion of biofuels obtained by pyrolysis and by transesterification and of biofuel/diesel blends

The obtained heats of combustion were 46.65 ± 0.20; 38.09 ± 0.31; 39.67 ± 0.22; 41.88 ± 0.31; 37.86 ± 0.46; 39.89 ± 0.09; 41.28 ± 0.31 MJ/kg for diesel, transesterified soybean oil, pyrolysed soybean oil and crude soybean oil, transesterified palm tree oil (Elaeis sp.), pyrolysed palm tree oil, crude palm tree oil, respectively. The results show the heats of combustion of biofuels are approximately 17% smaller than traditional diesel. The data also show the heats of combustion depend on the methodology used for the biofuel production. Addition of biofuels to traditional diesel fuel results in a linear decrease of the heat of combustion with the amount of the alternative fuel added to the diesel. However, for blends with 5% biofuels, which is the limit demanded by Brazilian legislation, no significant decrease of the heat of combustion of the commercial diesel was observed.     

Directed evolution of O6-alkylguanine-DNA alkyltransferase for efficient labeling of fusion proteins with small molecules in vivo

We report here the generation of mutants of the human O(6)-alkylguanine-DNA alkyltransferase (hAGT) for the efficient in vivo labeling of fusion proteins with synthetic reporter molecules. Libraries of hAGT were displayed on phage, and mutants capable of efficiently reacting with the inhibitor O(6)-benzylguanine were selected based on their ability to irreversibly transfer the benzyl group to a reactive cysteine residue. Using synthetic O(6)-benzylguanine derivatives, the selected mutant proteins allow for a highly efficient covalent labeling of hAGT fusion proteins in vivo and in vitro with small molecules and therefore should become important tools for studying protein function in living cells. In addition to various applications in proteomics, the selected mutants also yield insight into the interaction of the DNA repair protein hAGT with its inhibitor O(6)-benzylguanine.     

Synthesis of new monodendrons,gallic acid derivatives,self- assembled in a columnar phase

This article describes the synthesis and liquid crystal properties of new compounds that are derived from gallic acid. All the compounds were characterised by ¹H and ¹³C nuclear magnetic resonance spectroscopy (¹H NMR and ¹³C NMR), Infrared spectroscopy (IR) and Elemental analysis (CHN). The mesophases of these compounds were characterised using polarising optical microscopy (POM), differential scanning calorimetry (DSC) and SAXS measurements. The morphology of the surface of the films was investigated using atomic force microscopy (AFM). Compounds 9 and 13, which remain in a supercooled state until room temperature, do not exhibit liquid crystalline behaviour. The other compounds (i.e., 5, 7 and 8) self-assemble into tubular supramolecular architectures generating hexagonal columnar (Col_h) mesophases, which was confirmed by SAXS measurements.     

Why the pore geometry model could affect the uniqueness of the PSD in AC characterization

In this paper we discuss why the pore geometry can affect the unicity of the pore size distribution (PSD) of a given activated carbon (AC) sample, when different probe gases are used in adsorption measures. In order to characterize the solid sample we used grand canonical Monte Carlo simulation and the independent pore model with slit or triangular pore geometry, focusing our analysis on the possibility of representing the adsorptive processes of a triangular pore of defined size by means of a combination of slit pores of different sizes. This representation is tested on experimental adsorption data of N₂ (77 K) on AC samples and acceptable results were obtained. Finally, we have performed a theoretical test, which consisted of analyzing a virtual porous solid with this approach and different probe gases (N₂ at 77 K and CO₂ at 273 K), showing that the differences between the pore representations can cause differences between the solid representations for the adsorptive properties, for these different gases. The analysis presented here can be extended to other pore geometries and other adsorbates, and provide arguments to further explain results presented in our previous paper, which refers to cases when different adsorbates yield different PSDs for a given sample and the same pore geometry model.     

Two-photon sensitive photolabile protecting groups: From molecular engineering to nanostructuration

ABSTRACT

General molecular engineering rules for the optimization of two-photon sensitive cages are presented and examples for nitrobenzyl, indole and nitrophenethyl platforms are highlighted. The efficiency of electron donor and acceptor groups in dipolar structures and the length of the conjugated system in the photolabile protecting group on two-photon uncaging efficiency will be discussed, as well as the emergence of symmetrical platform based on bis-electron donor or on quadrupolar architectures. We will then present our first results on the nano-structuration of donor-acceptor systems based on nitrophenetyl platform using diethyleneglycol or pentaerythritol cores.     

Controllability Properties and Invariance Pressure for Linear Discrete-Time Systems

For linear control systems in discrete time controllability properties are characterized. In particular, a unique control set with nonvoid interior exists and it is bounded in the hyperbolic case. Then a formula for the invariance pressure of this control set is proved.

     

Revisiting the averaged problem in the case of mean-motion resonances in the restricted three-body problem

Nonlinear Dynamics - A classical approach to the restricted three-body problem is to analyze the dynamics of the massless body in the synodic reference frame. A different approach is represented by...     

Evolutionary computation for automatic Web service composition: an indirect representation approach

Web services have become increasingly popular in recent years, and they are especially suitable to the process of Web service composition, which is when several services are combined to create an application that accomplishes a more complex task. In recent years, significant research efforts have been made on developing approaches for performing Quality of Service -aware Web service composition. Evolutionary computing (EC) techniques have been widely used for solving this problem, since they allow for the quality of compositions to be optimised, meanwhile also ensuring that the solutions produced have the required functionality. Existing EC-based composition approaches perform constrained optimisation to produce solutions that meet those requirements, however these constraints may hinder the effectiveness of the search. To address this issue, a novel framework based on an indirect representation is proposed in this work. The core idea is to first generate candidate service compositions encoded as sequences of services. Then, a decoding scheme is developed to transform any sequence of services into a corresponding feasible service composition. Given a service sequence, the decoding scheme builds the workflow from scratch by iteratively adding the services to proper positions of the workflow in the order of the sequence. This is beneficial because it allows the optimisation to be carried out in an unconstrained way, later enforcing functionality constraints during the decoding process. A number of encoding methods and corresponding search operators, including the PSO, GA, and GP-based methods, are proposed and tested, with results showing that the quality of the solutions produced by the proposed indirect approach is higher than that of a baseline direct representation-based approach for twelve out of the thirteen datasets considered. In particular, the method using the variable-length sequence representation has the most efficient execution time, while the fixed-length sequence produces the highest quality solutions.