Immobilization of 5-amino-1,3,4-thiadiazole-thiol onto silica gel surface by heterogeneous and homogeneous routes

The compound 5-amino-1,3,4-thiadiazole-thiol (ATT) was anchored onto silica gel surfaces by homogeneous and heterogeneous routes. Both silica modification methodologies resulted in similar products, named SiCTT and SiATT, respectively. These materials were characterized by infrared and Raman spectroscopies, superficial area and elemental analysis as well as ¹³C and ²⁹Si NMR spectroscopy. Elemental analysis proved that the material SiCTT presented a higher ATT immobilization than SiATT, with values of 0.73 and 0.65 mmol g⁻¹, respectively. NMR, Raman and infrared spectroscopy corroborate to confirm the immobilization of ATT on both surfaces. Raman spectroscopy showed that the reaction of the ATT with silylant agent or pre-modified silica occurred by the thiol group, resulting in a surface with two sulfur groups and one free amine group able to complex soft and hard acids.     

Chemical beam epitaxy of AlGaAs and AlInAs using trimethylamine alane precursor

Al_xGa_1−xAs and Al_xIn_1−xAs alloys were grown on GaAs and InP, respectively, by chemical beam epitaxy, using trimethylamine alane (TMAA) as the source of aluminium. TMAA could be used properly only after some problems had been solved. Low carbon and oxygen concentrations were obtained in both alloys, leading to residual hole concentrations of 2 × 10¹⁶ cm^-3 in Al_0.3Ga_0.7As. The abruptness of the AlGaAs/GaAs interface proved the absence of TMAA memory effect. The control of Al_xIn_1−xAs solid composition was more difficult than for Ga_xIn_1−xAs, but was less sensitive to growth temperature. Photoluminescence intensities of Al_0.3Ga_0.7As and Al_0.48In_0.52As grown at 510°C were similar to those of MBE grown materials.     

Quasi-optimal Nonconforming Approximation of Elliptic PDEs with Contrasted Coefficients and $$H^{1+{r}}$$ , $${r}>0$$ , Regularity

Foundations of Computational Mathematics - In this paper, we investigate the approximation of a diffusion model problem with contrasted diffusivity for various nonconforming approximation methods....     

On the riesz charge of the lower envelope of δ-subharmonic functions

By potential theoretic methods involving the Cartan fine topology a recent result by two of the authors is extended as follows: The Riesz charge of the lower envelope of a family of 3 or more -subharmonic functions (no longer supposed continuous) in the plane equals the infimum of the charges of the lower envelopes of all pairs of functions from the family. As a key to this it is shown in two different ways that the (fine) harmonic measures of any 3 pairwise disjoint finely open planar sets have Borel supports with empty intersection. One proof of this uses the Jordan curve theorem and the fact that the set of inaccessible points of the fine boundary of a fine domain is Borel and has zero harmonic measure; the other involves Carleman-Tsuji type estimates together with a fine topology version of a recent result of P. Jones and T. Wolff on harmonic measure and Hausdorff dimension.     

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.