Influence of Ti Incorporation to Bimetallic Mesoporous Carbon in the Production of 2,5-Dimethylfuran from Biomass Derivatives

Catalysis Letters - Monometallic and bimetallic supported catalysts were developed to produce 2,5-dimethylfuran (DMF) trough hydrogenolysis of 5-(hydroxymethyl)furfural (HMF). Detailed...     

Adaptation of the van Genuchten expression to the effects of temperature and density for compacted bentonites

The main objective of this work is to highlight the influence of variables like temperature and porosity (dry density) on the water retention curve of expansive clays for the analysis of thermo-hydro-mechanical coupled processes (THM problem).The paper presents retention curves of MX-80 bentonite measured under isochoric conditions for different dry densities and temperatures. The influence of dry density on the water retention capacity depends on the suction range, the limiting value being around 30 MPa. For suctions above this threshold value, the retention capacity in terms of water content is higher as the dry density increases, whereas for lower suctions, the lower the dry density the higher the water content for a particular suction. The retention capacity decreases with temperature, more than predicted by the change in interfacial tension of air–water, especially for high temperatures and low suctions.Accordingly, some modifications of the van Genuchten [van Genuchten, M.Th., 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J., 44, 892–898.] law have been proposed to fit the experimental values. Effects of temperature and porosity on the water retention capacity (other than the traditionally included in the air entry value coefficient) were incorporated through empirical laws that resemble the experimental evidences. By a fitting process, values of the coefficients in those laws were determined for the material used in this work.Finally, several 1D THM simulations using the computer code “CODE_BRIGHT” have been performed in order to analyse the consequences of considering or not temperature and density influences on the water retention curve.     

Screening of lactic acid bacteria for fermentation of minced wastes of Argentinean hake (Merluccius hubbsi)

Sixteen strains of lactic acid bacteria were evaluated for their capacity of acidification of Merluccius hubbsi fish wastes obtained from a processing factory. Only three lactobacilli (Lactobacillus buchneri B-1837, Lactobacillus arizonensis B-14768 and Lactobacillus plantarum B-4496) were able to reduce the pH value to 4.0 or below when using glucose or sucrose as carbon source. Either with only 25 g l^?1 of glucose or sucrose, L. arizonensis B-14768 reduced the pH to 3.8 ± 0.2 within 24 h of fermentation. The acid tolerance test (pH 3.0 at 37 °C) for the strains presented D_pH3-values of 192, 383 and 767 min for L. buchneri, L. plantarum and L. arizonensis, respectively. However, at a lower pH value (pH 2.0) only L. arizonensis was significantly recovered after 45 min of exposure (D_pH2 68 min). Considering together the acidification capacity, the tolerance to other stresses (heat and bile salts) and the lower optimum temperature for the process, L. arizonensis is described as a suitable strain for M. hubbsi silage; constituting a promissory alternative for fish fermentation at location with temperate or cold climes.     

Multiple-beam Interferometers: Analogy with Aberrated Optical Systems and Adjustment Tolerances Estimation

Abstract

In this paper we study multiple interference produced by an interferometer when illuminated by an extended quasimonochromatic source. We define a relative modulation factor, which arises from grouping the interference terms for the same frequency. This relative modulation factor measures the departure from ideal behaviour of the interferometer. We also show that for some cases it is possible to associate a single aberrated optical system to each frequency, just as can be done for the single interference case, as was shown in a previous work; this allows an extension of the formalism presented therein. As an example, we calculate, for the case of a double-grating interferometer, the tolerance for the spatial extension of the source, where the modulation factor is close to unity.     

A computer algebra approach to verification and deduction in many-valued knowledge systems

 A theoretical result [10] that relates tautological consequence in many-valued logics to the ideal membership problem in algebra is revisited. The intended use of the approach in this article and its implementation is the verification of consistency and the automated extraction of knowledge in rule-based knowledge systems. Programs are written in the CoCoA language. Four RBS are studied to illustrate the implementation.     

Relative rotation number for stochastic systems: dynamical and topological applications

We introduce a concept of relative rotation number to unify many different approaches of rotation number in non-linear dynamical systems. We present an ergodic result of existence a.s. for stochastic systems. In higher dimension, we show that the natural idea of projecting into a plane does work well a.s. for any plane (different from deterministic systems where projections may be degenerate). A number of further properties (invariance by homotopy and by conjugacy) and applications are presented.     

Non‐Conventional Electrochemical Techniques for Assembly of Electrodes on Glassy Carbon‐Like PPF Materials and Their Use in a Glucose Microfluidic Fuel‐Cell

This paper addresses the electrochemical growth of PtAg and Au nanoparticles on pyrolyzed photoresist films (PPFs). The PtAg/PPF electrode was evaluated toward oxygen reduction reaction (ORR) in the absence and presence of glucose; meanwhile the electrocatalytic activity of Au/PPF was investigated for the glucose electrooxidation reaction (GOR) in 0.3 M KOH in the absence and presence of air as an oxygen source. The results obtained using the electrochemical studies showed that the PtAg/PPF electrode exhibited tolerance toward the ORR in the presence of low glucose concentrations. Moreover, Au/PPF showed good affinity toward glucose oxidation at high concentrations (50 and 100 mM) in the presence of oxygen instead further oxidations of glucose by‐products. Both electrocatalysts were evaluated as the cathode (PtAg/PPF) and the anode (Au/PPF) in a glucose microfluidic fuel cell (G‐μFC) constructed using a UV‐lithography technique and several sheets of different polymeric materials. The G‐μFC was tested using 100 mM glucose with 0.3 M KOH as electrolyte in the absence of an external source of nitrogen or oxygen as the fuel at zero flow rate; this cell reached a maximum power density of 0.085 mW cm⁻² using a low Pt loading (approximately 20% of weight percentage) mixed with non‐noble materials, such as Ag.     

Comparison of lidocaine and urapidil for prevention of hemodynamic response to tracheal intubation in patients in general good health

Ribosomes, sufficiently purified by physicochemical criteria (with the RNA/protein ratio equal to 1.6 - 1.7), were isolated from disintegrated C.perfringens cells, type A, strain BP6K, by ultracentrifugation or by fractionation with polyethylene glycol. The purified conjugates of ribosomes and C.perfringens toxoid, absorbed on aluminum hydroxide, were obtained. The ribosomal preparations had low toxicity and high protective activity: when used in a dose of 6 binding units, they protected guinea pigs and mice inoculated with 8 - 9 LD50 of C.perfringens culture.