Complete nonorientable minimal surfaces in R3

We consider complete nonorientable minimal immersionsx(M)⊇R ³. Assuming the double coverN ofM has finite total curvature, we generalize an argument of Lopez/Ros to give a sufficient condition for the instability ofx(M) in terms of the total curvature ofM and the genus γ of . We apply this condition to prove that if the immersion is regular thenx(M) is unstable. We also consider the case where the immersion is finitely branched, and we classify the possibilities under the assumption the is hyperelliptic.     

Importance of the Correlation between Width and Length in the Shape Analysis of Nanorods: Use of a 2D Size Plot To Probe Such a Correlation

Analysis of nanoparticle size through a simple 2D plot is proposed in order to extract the correlation between length and width in a collection or a mixture of anisotropic particles. Compared to the usual statistics on the length associated with a second and independent statistical analysis of the width, this simple plot easily points out the various types of nanoparticles and their (an)isotropy. For each class of nano‐objects, the relationship between width and length (i.e., the strong or weak correlations between these two parameters) may suggest information concerning the nucleation/growth processes. It allows one to follow the effect on the shape and size distribution of physical or chemical processes such as simple ripening. Various electron microscopy pictures from the literature or from the authors′ own syntheses are used as examples to demonstrate the efficiency and simplicity of the proposed 2D plot combined with a multivariate analysis.     

Automatic Electronic Tongue for On-Line Detection and Quantification of Organophosphorus and Carbamate Pesticides Using Enzymatic Screen Printed Biosensors

This work presents an automatic system, based on an electronic tongue, for resolution of mixtures of three pesticides. Inhibition detections were performed during the steady state of biosensors response. Three biosensors were built using two enzymes, electric eel (EE), genetically-modified Drosophila melanogaster (B131), and electric eel co-immobilized with drosophila melanogaster (BH). Calibrations curves for paraoxon, dichorlvos, and carbofuran were performed in the ranges 0.4–50.4 µM, 0.01–1.01 µM, 0.01–0.41 µM with LOD of 3.91 × 10^?8, 6.30 × 10^?11, and 5.84 × 10^?10, respectively. An artificial neural network (ANN) was used to model the combined response of three pesticides. A set of 19 mixtures were prepared in order to train the artificial neural network, the modeling was validated with a set of 6 spiked samples of river water. The error and recovery yields were found in consistent with expected values.     

Model independent bounds on reaction cross-sections in heavy-ion scattering

The coupled cluster equations first proposed by Coester and Kümmel and developed by Kümmel, Lührmann, and Zabolitsky are derived explicitly from the variational principle for the ground state energy (the “true” energy) using a new set of simple formulas relating density matrices (equal time limits of Green functions) to the coupled cluster functions. In this respect a simplification appears to be achieved by working with a normalized ground state wave function. The further transformation of the variational equations into the standard forms given by the previous authors differs mainly in its pedagogical aspects from ideas found in the existing literature.     

Rare earth doped α-alumina thin films prepared by pulsed laser deposition: structural and optical properties

-Al₂O₃ films doped with about 1% Eu³⁺ were grown on sapphire (012) substrates by pulsed laser deposition using an ArF excimer laser under 10^-4 mbar oxygen pressure and at temperatures higher than 1050 °C. The Eu doping rate was measured by Rutherford backscattering spectroscopy. The crystalline structure was determined by X-ray diffraction and transmission electron microscopy. The films are grown epitaxially on the sapphire substrate. The Eu³⁺ fluorescence spectra are constituted of narrow lines. By means of pulsed laser deposition, Eu³⁺ ions may be introduced into a single site of the -phase lattice, with a concentration that cannot be reached using conventional crystal-growth methods. PACS 81.15.Fg; 68.37.Lp; 78.55.Hx     

Addition of arenes to ethylene and propene catalyzed by ruthenium

TpRuII(CO)(Me)(NCMe) (Tp = hydridotris(pyrazolyl)borate) serves as a catalyst precursor for the conversion of benzene and ethylene or propene to alkylaromatic products. The reaction proceeds via the formation of the active catalyst TpRu(CO)(Ph)(NCMe) and is mildly selective for linear propylbenzene over isopropylbenzene.     

A New Route to Crystalline Salts of the Hydrolytic Dimer of Chromium(III)

Crystalline salts of the hydrolytic dimer of Cr(III), [Cr₂(μ-OH)₂(H₂O)₈]X₄·n H₂O (X = p-toluenesulfonate (tos) or mesitylene-2-sulfonate (dmtos)) have been prepared in good yields via a simple two-step procedure: H⁺ oxidation of Cr metal to give Cr²⁺ (T ≈? 70°) followed by O₂ oxidation, of Cr²⁺ to give the dimer (T ≈? 25°). The mechanism of conversion of Cr²⁺ into the dimer is discussed.     

Lipase from Carica papaya latex presents high enantioselectivity toward the resolution of prodrug (R,S)-2-bromophenylacetic acid octyl ester

Besides the well-known papain, lipolytic activity is another interesting enzymatic activity present in latex from Carica papaya. This lipolytic activity is strongly attached to the latex solid phase, resulting in a naturally immobilized biocatalyst. In this work we describe the kinetic resolution of (R,S)-2-bromophenylacetic acid octyl ester by Carica papaya crude latex and two partially purified latex fractions. Several parameters, such as substrate concentration and solvent effects were studied. The best results were obtained using decane as solvent with 50 mM of substrate and 50 mg/mL enzyme/reaction medium; under these conditions, a high enantioselectivity (E >200) was obtained with crude latex. A twofold increase of the initial rate maintaining E >200 was obtained using purified fractions without protease and without esterase. Lipase from Carica papaya latex is the most enantioselective wild-type enzyme ever described for the studied reaction.