Mineralogy, chemistry and potential applications of a white bentonite in San Juan province, Argentina

A white bentonite deposit of Pleistocene age located in San Juan Province, Argentina, has very promising commercial applications because of its mineralogy and physical and chemical properties. The bentonite occurs in the Lower Member of the Las Trancas Formation which is a hydrothermally altered rhyolitic to rhyodacitic pumice and breccia.Analysis shows the major minerals present are smectite and opal-CT along with minor amounts of quartz, clinoptilolite, feldspar and biotite. The majority of the quartz, clinoptilolite, and biotite occurs in the >325 mesh fraction. The smectite is mainly a sodium montmorillonite along with some calcium and magnesium in the exchange positions. The <2 μm fraction consists of almost pure smectite and opal CT. Scanning electron micrographs show a typical “corn flakes” texture, which is characteristic of sodium montmorillonite.The physical and chemical properties including particle size, surface area, water and oil absorption, swelling index, cation exchange capacity, viscosity, and brightness indicate after wet beneficiation, that the processed white bentonite could be used in many industrial applications. These include paper coating and filling, paint, pharmaceuticals, cosmetics and filtering agents. Also the fine particle size fraction of <2 μm could be used to make an excellent quality organoclay.     

The formation of biogenic amines by fermentation organisms

A total of 523 strains representing 35 species related to food fermentation organisms of practical importance were investigated for their potential for formation of biogenic amines (BA). The investigation was performed with resting cells in phosphate buffer (pH 5.5) and the formation of the following BAs was followed: putrescine, cadaverine, histamine, tyramine and 2-phenylethylamine. No potential was observed in species ofLactococcus, Leuconostoc, Pediococcus, Streptococcus and severalLactobacillus spp., such asL. pentosus andL. sake. A remarkable potential to form BA was observed in strains of carnobacteria,Lactobacillus buchneri, L. curvatus, L. reuteri, Staphylococcus carnosus and, to a lesser extent, inL. alimentarius, L. brevis, L. bavaricus, L. delbrueckii ssp.lactis, Micrococcus spp. andS. piscifermentans. In well known species with a practical function in the fermentation of dairy products, wine or cabbage a potential was observed for few strains only. In view of their role as starters in food fermentation, or their potential use in protective cultures and as probiotics, BA formation by the organisms has to be taken into consideration by selecting appropriate strains.

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Die Bildung von biogenen Aminen durch Fermentationsorganismen

Zusammenfassung Das Potential zur Bildung von biogenen Aminen (BA) wurde bei 523 Stämmen, die 35 Spezies aus dem Verwandtschaftsbereich der Lebensmittelfermentationsorganismen zugehörten, untersucht. Zu diesem Zweck wurden ruhende Zellen in Phosphatpuffer (pH 5,5) verwendet und die Bildung der folgenden BA verfolgt: Putrescin, Cadaverin, Histamin, Tyramin, 2-Phenylethylamin. Bei Spezies der GeneraLactococcus, Leuconostoc, Pediococcus, Streptococcus und einigenLactobacillus spp., darunterL. pentosus undL. sake fehlte dieses Potential. Eine deutliche Bildung von BA wurde bei Stämmen von Carnobakterien,Lactobacillus buchneri, L. curvatus, L. reuten undStaphylococcus carnosus beobachtet. Weniger ausgeprägt war die Aminbildung beiLactobacillus alimentarius, L. brevis, L. bavaricus, L. delbrueckii ssp.lactis, Micrococcus spp. undStaphylococcus piscifermentans. Ein Potential bei Spezies, die bei der Fermentation von Milch, Wein und Sauerkraut bekanntermaßen erwünscht sind, wurde nur bei wenigen Stämmen gefunden. In Anbetracht der Bedeutung bestimmter Spezies als Starterkulturen bei Lebensmittelfermentationen und der möglichen Anwendung als Schutzkulturen oder Probiotika ist die mögliche Bildung von BA durch Auswahl geeigneter Stämme ausreichend zu berücksichtigen.

     

Theoretical computations on ridge acoustic surface waves using the finite-element method

Theoretical computations have been carried out on ridge acoustic surface waves using the finite-element method. The results obtained agree substantially with experiments performed previously.     

Acute Phase Response as a Biological Mechanism‐of‐Action of (Nano)particle‐Induced Cardiovascular Disease

Inhaled nanoparticles constitute a potential health hazard due to their size‐dependent lung deposition and large surface to mass ratio. Exposure to high levels contributes to the risk of developing respiratory and cardiovascular diseases, as well as of lung cancer. Particle‐induced acute phase response may be an important mechanism of action of particle‐induced cardiovascular disease. Here, the authors review new important scientific evidence showing causal relationships between inhalation of particle and nanomaterials, induction of acute phase response, and risk of cardiovascular disease. Particle‐induced acute phase response provides a means for risk assessment of particle‐induced cardiovascular disease and underscores cardiovascular disease as an occupational disease.     

Impact of Thermal Oxidation on Morphological,Structural and Magnetic Properties of Fe-Ni Wire-Like Nanochains

Metallurgical and Materials Transactions A - This work presents the evolution of morphological, structural and magnetic properties of amorphous Fe-Ni wire-like nanochains caused by thermal...     

Gender Differences in the VDR-FokI Polymorphism and Conventional Non-Genetic Risk Factors in Association with Lumbar Spine Pathologies in an Italian Case-Control Study

Recently, the FokI polymorphism (rs2228570) in the vitamin D receptor gene (VDR) and conventional risk factors were associated with spine disorders in the Italian population, but without gender analysis. Two-hundred and sixty-seven patients (149 males, 118 females) with lumbar spine disorders were assessed by magnetic resonance imaging (MRI) and 254 (127 males, 127 females) asymptomatic controls were enrolled. The exposure to putative risk factors was evaluated and FokI polymorphism was detected by PCR-restriction fragment length polymorphism (PCR-RFLP). An association between lumbar spine pathologies and higher than average age; overweight; family history; lower leisure physical activity; smoking habit; higher number of hours/day exposure to vibration and more sedentary or intense physical job demand was observed in male patients. In contrast, in females, only higher age, overweight, family history and lower leisure physical activity were risk factors. FF genotype was a 2-fold risk factor to develop discopathies and/or osteochondrosis concomitant with disc herniation for both gender patients, while heterozygous Ff was protective for females only. In males only ff genotype was protective for discopathies and/or osteochondrosis and F allele was a 2-fold risk factor for hernia; discopathies; discopathies and/or osteochondrosis. Sex-related differences in voluntary behaviors, exposure to environmental risks and genetic background could be crucial for a gender-differentiated management of patients with spine disorders.     

Mechanisms of Hydrogen Induced Stress Crack Initiation and Propagation in Super Duplex Stainless Steels

Austenitic and ferritic duplex stainless steels, DSS, have recently suffered from hydrogen stress induced cracking, HISC, in subsea components with a cathodic protection. This paper provides discussions on possible HISC mechanisms. HISC initiation can occur at the ferritic grain boundaries and phase boundaries at a stress lower than the yield strength, but dominantly at phase boundaries at a stress higher than the yield strength. EBSD analysis shows that HISC in DSS results from the interaction between the dynamic plasticity by creep and hydrogen diffusion. A model on the formation of microstresses in these two phases under creep conditions is proposed, which explains why HISC occurs mainly in the ferritic phase. Discontinuous two‐dimensional HISC paths were observed. The austenitic phase acts as obstacles for crack propagation. The fracture covers “valleys” and “peaks” with the cleavage ferrite and the austenite with microfacets or striations due to the hydrogen‐enhanced localized‐plasticity.     

A comparison of Euclidean Distance,Travel Times,and Network Distances in Location Choice Mixture Models

Networks and Spatial Economics - This article investigates the selection of a distance measure in location modeling. While in the empirical literature the choice usually boils down to picking one...     

A three-dimensional carbon-coated LiFePO4 electrode for high-power applications

The fabrication process of a new, three-dimensional carbon-coated LiFePO₄ electrode by sol–gel synthesis in situ on interconnected conducting fibers of carbon paper is described. This three-dimensional structure ensures overall electrode conductivity, facilitates lithium diffusion in and out of LiFePO₄ particles and, hence, enables good cycling stability at 1C-rate and maximum pulse-power values that exceed those of planar LiFePO₄ electrodes at high electrode loading.