Catalytic effect of metal cations on the darkening reaction in ripe olive processing

The darkening step in ripe olive processing can be accelerated by using different metal cations, particularly cobalt, manganese and iron, in the aeration liquid. It was found that manganese and iron ions increased the rate of the darkening reaction as their content in the liquid increased from zero to 9 mM. Manganese cations only had a catalytic effect on the darkening reaction, while iron ions also fixed the dark colour formed when olives were bottled and sterilized. However, the rate of oxidation of the orthodiphenols in the olive flesh (hydroxytyrosol and caffeic acid) was slightly modified when manganese or iron was added to the aeration liquid. The better dark surface colour obtained when manganese or iron ions were added to the aeration liquid remained after bottling and sterilization of olives in a ferrous gluconate solution. These results suggest that manganese could be used to catalyse the darkening reaction since this cation is generally recognized as safe.     

Influence of decantation of viura must on the cation content. Evolution during wine fermentation and stabilization

Must has many metallic cations which greatly affect wine fermentation, stability and quality. In this study we investigated the influence of clarification of viura must by static sedimentation studying the concentration of four macroelements (potassium, calcium, magnesium and sodium) and of four oligoelements (iron, copper, zinc and manganese). This treatment eliminated potassium (11%), calcium (25%), and a greater proportion of iron (46%). The evolution of cations during fermentation was similar in the clarified sample and in the control. Both young and stablised wines had similar concentrations of these elements.     

Survey of Listeria monocytogenes in ready-to-eat products: Prevalence by brands and retail establishments for exposure assessment of listeriosis in Northern Spain

The prevalence of Listeria monocytogenes in ready-to-eat products of markets in Northern Spain was studied, being analyzed 783 samples of deli meat products, smoked fish and pâté. RTE smoked fish was the most frequently contaminated food category (25% positive), with high occurrence in some brands (60% of lots positive). Significant differences in prevalence were found in in-store-packaged deli meat products (8.5%) with respect to manufacturer vacuum-packaged presentation (2.7%). Serological and molecular characterization of L. monocytogenes isolates confirmed the persistence of several clusters within manufacturing environments, as the same pulsotype was repeatedly isolated from different lots of the same brand and from different sliced products of the same store. These results reflect the need to improve hygiene and disinfection programs by addressing more accurate cleaning practices and continuous education of food workers.     

On polyethylene chain generation through chemical crosslinking of isotactic polypropylene

Crosslinked isotactic polypropylene (iPP) was prepared by reactive blending using dicumyl peroxide and active sulfur. The modified material was characterized by means of several techniques: dynamic mechanical thermal analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance (¹³C solid state NMR). Analysis of results using the above techniques confirms that, during the crosslinking process, new ethylenic chains are generated at expenses of the initially present iPP. Furthermore, a balance between the amount of missing iPP and the proportion of newly created polyethylene (PE) is observed. The newly formed PE is semicrystalline, having a degree of crystallinity of about 30%. The amorphous component of the generated PE is thought to contribute to the high impact strength of the crosslinked samples when compared to the unmodified iPP. In light of the results obtained by the different techniques, an attempt to describe the emerging structure of the new crosslinked iPP material is proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Complementary geometric formulations for electrostatics

The simultaneous use of a pair of complementary discrete formulations for electrostatic boundary value problems (BVPs) allows to accurately compute electromagnetic quantities, such as capacitance or electrostatic force with a minimum computational effort. In fact, the two formulations provide the upper and lower bounds for these quantities and their averages result quite close to the exact solution even for extremely coarse meshes. Despite the potential benefit to the many three‐dimensional large‐scale applications, taking advantage of this feature is not exploited in practice due to theoretical difficulties in the potential design. The aim of this paper is to fill this gap by rigorously introducing a pair of three‐dimensional complementary geometric formulations to solve electrostatic BVPs on domains covered by conformal polyhedral meshes. In particular, an original formulation based on a vector potential is introduced by using cohomology theory with integer coefficients. It is shown how the so‐called thick links are needed, which are representatives of the second cohomology group generators of the dielectric region. Two easy‐to‐implement graph‐theoretic algorithms to automatically find such a basis with optimal computational complexity are described. Some benchmark problems are presented to show how the simultaneous use of both formulations yields to a sensible computational advantage. Therefore, solvers based on complementary formulations should be embedded in the next‐generation of electromagnetic Computer‐Aided Engineering (CAE) softwares. Copyright © 2010 John Wiley & Sons, Ltd.     

Composites with needle-like inclusions exhibiting negative thermal expansion: A preliminary investigation

In this work a simple cylindrical structure with a stiff needle-like inclusion embedded within a much softer matrix is presented and analysed with the aim of obtaining a system with tunable thermal expansion properties. It is shown that by the correct combination of the thermal and mechanical properties of the matrix and inclusion, it is possible to design a system which can be tailor-made to exhibit particular values of the coefficient of thermal expansion (CTE) in the radial direction and also negative thermal expansion (NTE). In particular an analytical model to quantify the radial strain with changes in temperature is derived and verified through finite element analysis. The model is used to find correct property combinations which lead to particular values of thermal expansion which could also be negative or zero.     

ATP-diphosphophydrolase activity in rat heart tissue

Extracellular nucleotides interact with specific receptors on the cell surface and are locally metabolized by ecto-nucleotidases. Biochemical characterization of the ATPase and ADPase activities detected in rat heart sarcolemma, under conditions where mitochondrial ATPase and adenylate kinase were blocked, supports our proposal that both activities correspond to a single enzyme, known as ATP-diphosphohydrolase or apyrase. The physiological function of this enzyme could be dephosphorylation of the nucleotides present in the interstitial heart compartment acting together with 5'-nucleotidase. Both hydrolytic activities have similarities in: sarcolemma localization, bivalent metal ion dependence, optimum pH, effect of several amino acid residue modifiers, competitive inhibition of nucleotide analogs, and broad nucleoside di-and triphosphate specificity. The ATPase activity could not be separated from the ADPase either through isoelectrofocusing or electrophoresis under acid conditions.     

Fabrication of semi-conductive ceramics by combination of gelcasting and reduction sintering

In this study, we propose a new process to fabricate electrically semi-conductive alumina by the combination of gelcasting and reduction sintering. The process is similar to the conventional gelcasting method except for varying amounts of methacrylamide monomer dosages at 2.83, 5.50, and 8.04 wt% relative to the mass of the slurry. Correspondingly, the rheological evaluation of aqueous slurry was conducted. The resulting fluidity exhibited that monomer dosage until 8.04 wt% yielded slurry viscosity of 1628 MPA·s at shear rate of 20 s⁻¹, which was feasible for gelcasting without noticeable casting defects. The freshly gelled bodies were demolded, carefully dried, and then sintered at different schedules in nitrogen atmosphere. The reduction-sintered samples were re-sintered in air for comparative evaluation of physical property. The sintered alumina body was characterized by electrical resistance, X-ray diffraction, and scanning electron microscopy. The results showed that monomer additions and sintering schedule significantly affect in lowering electrical resistivity. The obtained lowest value was 3.6 × 10⁶ Ω-cm with 8.04 wt% monomer dosage and sintering at 1550°C with 2 h holding time. The resulting material is classified as semi-conductive, which is potential for electrostatic shielding applications. The effect of physical property and microstructure on electrical conductivity and the corresponding reaction mechanism were discussed in details.     

The Timing of Uncertainty and the Intensity of Policy

This article analyzes the trade-off between `caution' and `intensity' in the use of the control variable in a one-state one-control dynamic stochastic quadratic linear optimization problem with discount factor. It studies the effects that changes in uncertainty of the control parameter have on the optimal first period response of the control variable, showing that the trade-off between `caution' and `intensity' depends on the timing of the uncertainty. Given an increase in current uncertainty and an equal increase in future uncertainty, caution will always prevail over intensity. Moreover, the prevalence of caution will be enlarged as the increase in future uncertainty moves farther away into the future, while this prevalence will be reduced as the increase in future uncertainty expands into the future. Finally, for the infinite horizon case, caution is the optimal policy response.     

Prompt fission-neutron spectra in the reactions of 1.5-MeV neutrons with235U

Translated from Atomnaya énergiya, Vol. 69, No. 1, pp. 28–31, July, 1990.