One-sided ideals and right cancellation in the second dual of the group algebra and similar algebras

The following results are proved for a non-compact, locallycompact group G: the dimension of every non-trivial right idealin L¹(G)** (equipped with the first Arens product) is at least, where (G) is the minimalnumber of compact sets required to cover G; there exist left ideals in L¹(G)** and in LUC(G)* with trivialintersections, and the linear span of right-cancellable elementsis weak*-dense in the annihilator of C₀(G) in LUC(G)* and inthe annihilator of (theL-functions that vanish at infinity) in L(G)*. The same resultsare proved for weighted algebras when the weight function isdiagonally bounded.     

Synthesis, antibacterial, antifungal and antiviral activity evaluation of some new bis-Schiff bases of isatin and their derivatives

Twelve new bis-Schiff bases of isatin, benzylisatin and 5-fluoroisatin 3a-3l were prepared by condensation of isatin, benzylisatin and 5-fluoroisatin with primary aromatic amines. The chemical structures of the products were confirmed by 1H- and 13CNMR, IR and mass spectral data. The compounds were screened for antiviral activity against a panel of DNA and RNA viruses. Minimum cytotoxic and minimum virus-inhibitory concentrations of these compounds were determined. Compounds 3c and 3i were the most cytotoxic in HEL cells. These newly synthesized bis-Schiff bases were also tested for their antibacterial and antifungal activities. They did not display activity against S. cerevisiae (ATCC 28383) or C. albicans (CIP 1180-79).     

Chemo-bio catalyzed synthesis of <Emphasis Type="Italic">R</Emphasis>-1-phenylethyl acetate over bimetallic PdZn catalysts,lipase, and Ru/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>. Part II

One-pot synthesis of R-1-phenyethylacetate at 70°C was investigated using three different catalysts simultaneously, namely a bimetallic PdZn/Al₂O₃ as a hydrogenation catalyst, an immobilized lipase as an acylation catalyst and Ru/Al₂O₃ as a racemization catalyst. The most active bimetallic catalyst was PdZn/Al₂O₃ calcined at 300°C and reduced at 400°C, whereas the most selective although less active catalyst was the one being calcined and reduced at 500°C. The highest selectivity to R-1-phenylethyl acetate over this catalyst was 32 at 48% conversion. Ru/Al₂O₃ was confirmed to have a positive effect on the formation of the desired product, although it was not very active in the racemization during one-pot synthesis.     

Lipase-catalyzed acylation in a continuous down-flow fixed-bed reactor

The kinetic resolution of racemic 1-phenylethanol with ethyl acetate was investigated in a down-flow fixed-bed reactor operated in a continuous mode mainly at the molar ratio of 1: 3 in 400 mL toluene at 70°C. The catalytic activity of the immobilized lipase was studied by: (i) changing the flow rates, (ii) utilizing different substrate concentrations, (iii) applying step changes using ethyl acetate, ethyl benzene, acetic acid, acetophenone etc., (iv) investigating the inhibitory effect of either the desired or the stoichiometric products (R)-1-phenylethyl acetate and ethanol, respectively), (v) elucidating the effect of water on the activity and stability of the immobilized lipase. The residence time distribution and the reactor hydrodynamics were also discussed along with kinetic modelling. The results were linked to the one-pot reactions.     

Apparent and effective mechanical properties of linear matrix-inclusion random composites: Improved bounds for the effective behavior

This paper is devoted to the derivation of improved bounds for the effective behavior of linear elastic matrix-inclusion composites based on a strategy which is inspired by both the works of Huet, 1990, Danielsson et al., 2007. As shown by the former author, the effective properties of random linear composites can be bounded by ensemble averages of their apparent elastic moduli defined on square (or cubic) volume elements (VEs) and computed with either affine displacement Boundary Conditions (BC) or uniform traction BC. However, in the case of a large contrast of the constituents, the discrepancy between the upper and lower bounds remains significant, even for large values of the VE size. This occurs because the contribution to the total potential (or complementary) energy of the particles (or pores) which intersect the edges of the VE becomes unphysically very large when uniform BC are directly applied to the particles. To avoid such limitations, we considerer non-square (or non-cubic) VEs consisting in simply connex assemblages of cells, each cell being composed of an inclusion surrounded by the matrix, thus forbidding any direct application of BC to the particles. Such VEs are generated by extending the scheme proposed by Danielsson et al. (2007) in the context of periodic random microstructures to fully random microstructures. By applying the classical energy bounding theorems to the non-square VEs, new bounds for the effective behavior are derived. Their application to a two-phase composite composed of an isotropic matrix and aligned identical fibers randomly distributed in the transverse plane leads to sharper bounds which converge quickly with the VE size, even for infinite contrasts.     

Air Pollution Measurements by Means of a Beta Gauge

In this paper an evaluation about the performances of a beta gauge for air pollution monitoring developed by the authors has been worked out. The apparatus is quite interesting for airborne particulate measurements, and it seems to be useful in several other applications in the field of environmental sciences.     

Mechanisms of Asymmetric Heterogeneous Catalysis1

Asymmetric catalysis plays an important role in present-day production of pharmaceuticals. It can be predicted that enantioselective catalysis will dominate in the future, replacing conventional stoichiometric methods. Heterogeneous catalysts offer several advantages compared to their homogeneous counterparts. In the present review mechanisms of asymmetric heterogeneous catalysis are discussed and the different ways of chirality transfer are addressed. Enantioselection is possible over chiral supports and chiral metals exhibiting intrinsic chirality, as well as over modified metal supported catalysts. The interactions between a reactant and a modifier are very specific being critical for achieving high enantioselectivities.     

Effect of Zn Substitution on Magnetic Properties of CuFe_2O_4: a High-Temperature Series Expansions Study

The magnetic properties of spinel ferrites Cu_(1-x)Zn_xFe_2O_4 are studied using high-temperature series expansions combined with the Padé approximates. The exchange interactions, inter and intra-sublattices J_(AA), J_(BB) and J_(AB) are obtained using a probability distribution law. The critical exponent associated with the magnetic susceptibility is obtained.     

Picomolar Detection of Melamine Using Molecularly Imprinted Polymer‐Based Electrochemical Sensors Prepared by UV‐Graft Photopolymerization

Molecularly imprinted polymer (MIP) films of melamine were prepared by photopolymerization of vinylic monomers on diazonium‐modified gold electrodes. The gold‐grafted MIPs are specific and selective for melamine in either organic or aqueous media. The interferent molecules cyromazine and cyanuric acid were not recognized by the MIPs. The limit of detection was as low as 1.75×10^?12 mol L^?1 at S/N=3. Efficiency of melamine rebinding is related to the solubility parameter of the organic solvent or pH and ionic strength of the aqueous medium. It is concluded that diazonium salts permit to design robust electrochemical MIP sensors.