<Emphasis Type="Italic">Listeria</Emphasis> Inactivation by the Combination of High Hydrostatic Pressure and Lactocin AL705 on Cured-Cooked Pork Loin Slices

The effect of the bacteriocin lactocin AL705 in combination with high hydrostatic pressure (HHP) on the inactivation of Listeria innocua 7, a nonpathogenic indicator for Listeria monocytogenes, deliberately inoculated (ca. 6.4 log CFU/g) onto the surface of ready-to-eat (RTE) sliced cured-cooked pork loin, was evaluated. Nontreated pork slices (control) and treatments subjected to lactocin AL705 (105 AU/ml) and/or HHP (400 or 600 MPa) were prepared. L. innocua 7 was monitored at days 1, 20, and 40 of storage at 4 °C. The results showed a complete inhibition of L. innocua 7 after the combined treatment with lactocin AL705 and 600 MPa and no regrowing of cells up to 40-day storage. The treatment at 600 MPa alone was not enough to avoid regrowth of L. innocua. Ultrastructural cell damage was observed at the cytoplasm and cell membrane/wall levels with all treatments; however, complete cell lysis was observed only with the combined treatment. HHP in combination with lactocin AL705 provided a wider margin of safety as post-processing listericidal treatment of RTE cured-cooked meat products.     

The electrochemical behaviour of different graphite/cryolite alumina melt interfaces under potentiodynamic perturbations

The anodic reaction in molten cryolite alumina systems has been studied in a wide range of potentials by applying both repetitive and single pulse linear sweep voltammetry, varying the sweep rate between 0.04 V/s and 600 V/s, and the alumina concentration between 0.05 and 1.5 wt%.The experimental results obtained at slow sweep rates were interpreted taking into account that the hydrodynamic conditions which prevail at the anodic interface are defined by the gas flow caused by the anodic reaction. At fast sweep rates, under conditions of linear diffusion, a mechanism for the oxide ion discharge is postulated. The low value of the diffusion coefficient of the oxide ion species, calculated from fast sweep rate experiments indicates a prior chemical equilibrium step. At fast sweep rates, a new voltammetric peak is reported, probably associated with the COF₂ formation.     

Oral Absorption and Disposition of alpha‐Linolenic,Rumenic and Vaccenic Acids After Administration as a Naturally Enriched Goat Dairy Fat to Rats

Although there is extensive information describing the positive biological effects of conjugated linoleic acid and its main isomer rumenic acid (RA; C18:2 cis 9, trans 11), and alpha‐linolenic acid (ALA) and vaccenic acid (TVA), data about their bioavailability are not available. In this work, we investigated the oral absorption and disposition of these fatty acids in Wistar rats. A naturally enriched goat dairy fat (EDF) was obtained by supplementing ruminant diets with oils or oilseeds rich in polyunsaturated fatty acids (PUFA). The EDF was administered orally (single dose of 3000 mg EDF/kg body weight equivalent to 153 mg TVA/kg body weight, 46 mg RA/kg body weight and 31 mg ALA/kg body weight), and serial blood and liver samples were collected and TVA, RA and ALA concentrations determined by GC/MS. The fatty acids TVA, RA and ALA were rapidly absorbed (t_1/2a, 0.36, 0.66 and 0.76 h, respectively, for plasma) and slowly eliminated (t_1/2β, 17.04, 18.40 and 16.52 h, respectively, for plasma). The maximum concentration (C_max) was detected in liver > plasma > erythrocyte. Our study shows that when orally administered EDF, its components TVA, RA and ALA were rapidly absorbed and distributed throughout the body by the blood circulation to exert systemic effects.     

Induction of metallothionein in astrocytes and microglia in the spinal cord from the myelin-deficient jimpy mouse

Jimpy is a shortened life-span murine mutant whose genetic disorder results in severe pathological alterations in the CNS, including hypomyelination, oligodendrocyte death and strong astroglial and microglial reaction. The knowledge of metallothionein (MT) regulation in the CNS and especially of MT presence in specific glial cell types under pathological conditions is scarce. In the present study, immunocytochemical detection of MT-I + II has been performed in spinal cord sections from 10-12- and 20-22-day-old jimpy and normal animals. The identification of MT-positive glial cells was achieved through double labeling combining MT immunocytochemistry and selective markers for oligodendrocytes, astrocytes and microglia. MT was found in glial cells and was present in the spinal cord of jimpy and normal mice at both ages, but there were remarkable differences in MT expression and in the nature of MT-positive glial cells depending on the type of mouse. The number of MT-positive cells was higher in jimpy than in normal spinal cords. This was apparent in all spinal cord areas, although it was more pronounced in white than in the gray matter and at 20-22 days than at 10-12 days. The mean number of MT-positive glia in the jimpy white matter was 1.9-fold (10-12 days) and 2.4-fold (20-22 days) higher than in the normal one. Astrocytes were the only parenchymal glial cells that were positively identified as MT-producing cells in normal animals. Interestingly, MT in the jimpy spinal cord was localized not only in astrocytes but also in microglial cells. The occurrence of MT induction in relation to reactive astrocytes and microglia, and its role in neuropathological conditions is discussed.     

Asymptotic Analysis of Coagulation–Fragmentation Equations of Carbon Nanotube Clusters

The possibility of the existence of single-wall carbon nanotubes (SWNTs) in organic solvents in the form of clusters is discussed. A theory is developed based on a bundlet model for clusters describing the distribution function of clusters by size. The phenomena have a unified explanation in the framework of the bundlet model of a cluster, in accordance with which the free energy of an SWNT involved in a cluster is combined from two components: a volume one, proportional to the number of molecules n in a cluster, and a surface one, proportional to n ^1/2. During the latter stage of the fusion process, the dynamics were governed mainly by the displacement of the volume of liquid around the fusion site between the fused clusters. The same order of magnitude for the average cluster-fusion velocity is deduced if the fusion process starts with several fusion sites. Based on a simple kinetic model and starting from the initial state of pure monomers, micellization of rod-like aggregates at high critical micelle concentration occurs in three separated stages. A convenient relation is obtained for <n> at transient stage. At equilibrium, another relation determines dimensionless binding energy α. A relation with surface dilatational viscosity is obtained.     

A comparative activity study of a new ultra-dispersed catalyst system for a hydrocracking/hydrotreating technology using vacuum residue oil: Merey/Mesa

Ultra-dispersed catalysts give an improvement over the main reactions activity by having a low deactivation rate. They provide as well other advantages like a diminution in the catalysts metal concentration, a reduction in contaminants and also these catalysts can be used in almost every area where heterogeneous catalysts are used. Catalysts synthesis optimization is important to improve process recovery, especially in hydrocracking/hydrotreating processes, where feedstock is vacuum residue. Here, we have evaluated the catalytic performance of two molybdenum–nickel catalysts prepared using different emulsion formulation, named E-T (base catalyst) and AT-48 (new catalyst). Our results showed that, the percentage of converted products for VR 500 °C⁺, asphaltenes and microcarbon are comparable for both E-T and AT-48 catalysts, despite the fact that for the latter a lower molybdenum concentration was used. In addition, post-catalytic particles analyses using SEM and TEM techniques demonstrated that AT-48 catalyst showed a non-aggregated and homogeneous narrower distribution of metallic particles than E-T one. The lower average particle size distribution is related to the improvement of the liquid product yields for the hydroconversion of Mery/Mesa VR using the AT-48 catalyst.     

Effect of packing on the cluster nature of C nanotubes: An information entropy analysis

The possibility of the existence of single−wall carbon nanotubes (SWNTs) in organic solvents in the form of clusters is discussed. A theory is developed based on a bundlet model for clusters, which enables describing the distribution function of clusters by size. Comparison of the calculated values of solubility with experiments would permit obtaining energetic parameters characterizing the interaction of an SWNT with its surrounding, in a solid or solution. Fullerenes and SWNTs are unique objects, whose behaviour in many physical situations is characterized by remarkable peculiarities. Peculiarities in solutions show up first in that fullerenes and SWNTs represent the only soluble forms of carbon, what is related to the originality in the molecular structure of fullerenes and SWNTs. The fullerene molecule is a virtually uniform closed spherical or spheroidal surface, and an SWNT is a smooth cylindrical unit. Both structures give rise to the relatively weak interaction between the neighbouring molecules in a crystal and promote interaction of the molecules with those of a solvent. Another peculiarity in solutions is related to their trend to form clusters, consisting of a number of fullerene molecules or SWNTs. The energy of interaction of a fullerene molecule or SWNT with solvent molecules is proportional to the surface of the former molecule and roughly independent of the orientation of solvent molecules. All these phenomena have a unified explanation in the framework of the bundlet model of a cluster, in accordance with which the free energy of an SWNT involved in a cluster is combined from two components, viz. a volume one proportional to the number of molecules n in a cluster, and a surface one proportional to n^1/2. Algorithms for classification are proposed based on the criteria information entropy and its production. Many classification algorithms are based on information entropy. When applying these procedures to sets of moderate size, an excessive number of results appear compatible with data, and this number suffers a combinatorial explosion. However, after the equipartition conjecture, one has a selection criterion between different variants resulting from classification between hierarchical trees. According to this conjecture, for a given charge or duty, the best configuration of a flowsheet is the one in which the entropy production is most uniformly distributed. Information entropy, cluster and principal component analyses agree.