Prebiotic synthesis of sequential peptides on the Hadean beach by a molecular engine working with nitrogen oxides as energy sources

Addressing the still open question of the prebiotic origin of sequential macromolecules (peptides, nucleic acids) on the primitive Earth, we describe a molecular engine (the primary pump), which works at ambient temperature and continuously generates, elongates and complexifies sequential peptides. This new scenario is based on a cyclic reaction sequence, whose keystep is the activation of amino acids into their N‐carboxyanhydrides (NCA) through nitrosation by NOx. This process could have taken place on tidal beaches; it requires a buffered ocean, emerged land and a nitrosating atmosphere. With the help of geochemical studies and computer simulations of atmosphere photochemistry, we show that the primitive Earth during the Hadean may have satisfied all these requirements. © 2001 Society of Chemical Industry.     

Lack of de-epoxidation of type B trichothecenes in incubates with human faeces

The ability of human gastrointestinal organisms to transform the trichothecenes 3-acetyldeoxynivalenol and nivalenol was investigated. Samples of human faeces were incubated under anaerobic conditions for 48 h with the toxins. They were then extracted and analysed for trichothecenes and metabolites. 3-Acetyldeoxynivalenol was metabolized to deoxynivalenol during the incubation period. In contrast to what has been reported for other species such as rats, mice and pigs, no de-epoxidated metabolites were detected in the faecal incubates. The toxicological significance of the difference in the intestinal ability to transform trichothecenes between species is unknown.     

Dissolution kinetics of ulexite in acetic acid solutions

Ulexite is an important boron mineral used for the production of boron compounds. The aims of this study are to examine the dissolution kinetics of ulexite in acetic acid solutions, and to present an alternative process to produce boric acid. In order to investigate the dissolution kinetics of ulexite in acetic acid solutions, the concentration of solution, reaction temperature, solid-to-liquid ratio, and particle size were selected as experimental parameters. It was determined that the dissolution rate of ulexite increased with increasing solution concentration and temperature and decreasing particle size and solid-to-liquid ratio. The activation energy of the process was found to be 55.8 kJ/mol.     

Use of postconsumer polyethylene in blends with polyamide 6: Effects of the extrusion method and the compatibilizer

Blends of polyamide and high‐density polyethylene show adequate properties for a large range of applications: they are used for the production of filaments, containers, and molding resins. The effect of the addition of 2 wt % of a compatibilizer, maleic anhydride grafted polyethylene, to the blend was studied and compared to the use of postconsumer polyethylene. The samples were extruded with single‐ and twin‐screw extruders with 25, 50, or 75 wt % f polyethylene, and the test specimens, molded by injection, were characterized by stress–strain tests, thermal properties, and morphologies. Processing the blends with postconsumer polyethylene in both extruders improved the mechanical properties in comparison to the blends processed with high‐density polyethylene and the compatibilizer. The morphologies of these blends showed that there was a decrease in the domain size of the disperse phase with the use of the compatibilizer or postconsumer polyethylene. The results indicate that for this blend, postconsumer polyethylene substituted, with advantages, for the necessity of a compatibilizer and the use of the high‐density polyethylene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Extended Hyperbolic Model for Sand-to-Concrete Interfaces

A relatively simple, four-parameter extended hyperbolic model for interfaces was developed for use in soil-structure interaction analyses. The model accommodates arbitrary stress path directions and includes three important elements: (1) development of a yield surface during interface shear; (2) a formulation for yield-inducing shear stiffness that is applicable to any stress path orientation; and (3) a formulation for unloading-reloading shear stiffness. The model was evaluated against the results of shear tests performed at the interface between three different types of sand and a concrete surface under a variety of stress paths. Comparisons between measured and calculated interface response indicate that the model provides accurate estimates of the response of sand-to-concrete interfaces.     

Does social dominance generate prejudice? Integrating individual and contextual determinants of intergroup cognitions.

Social dominance orientation (SDO) has been proposed as an important variable in the explanation of prejudice. We distinguish between three conceptualizations of SDO: SDO as a personality trait (personality model), SDO as a moderator of the effects of situational variables (Person X Situation model), and SDO as a mediator of the effect of social position on prejudice (group socialization model [GSM]). Four studies (N = 1,657) looking at the relations between social positions, SDO, and prejudice in a natural setting and in a laboratory setting provide strong support for the GSM. In contrast to previous correlational findings, there is evidence of a cause (dominant social position), an effect (prejudice increases), and a mediator (SDO). These results suggest new perspectives on the integration of individual and contextual determinants of prejudice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oil yield and compressibility modeling during microscale expression: Criteria for linseed breeding

Seven linseed varieties were harvested at seven times before complete maturity. Microscale oilseed expressions were subsequently carried out on it. A pressure of 10 MPa was applied for 1 h under uniaxial stress. The results were characterized in terms of oil, water and mucilage content, harvest date and oil yield. The piston displacement versus time (creep curves) was described by a four‐Kelvin‐Voigt elements viscoelastic model. Parameters were derived from the model, such as the mechanical properties of seeds (compressibility moduli), showing that the viscoelastic model fits well the experimental data (R² ≈ 0.999). The modeling parameters were combined with some biochemical data in order to predict the kinetics of oil extraction.     

Nisin expression production from Lactococcus lactis in milk whey medium

BACKGROUND: Nisin is a commercially available bacteriocin produced by Lactococcus lactis ATCC 11454 and used as a natural agent in the biopreservation of food. In the current investigation, milk whey, a byproduct from dairy industries was used as a fermentation substrate for the production of nisin. Lactococcus lactis ATCC 11454 was developed in a rotary shaker (30 °C/36 h/100 rpm) using two different media with milk whey (i) without filtration, pH 6.8, adjusted with NaOH 2 mol L^?1 and without pH adjustment, both autoclaved at 121 °C for 30 min, and (ii) filtrated (1.20 µm and 0.22 µm membrane filter). These cultures were transferred five times using 5 mL aliquots of broth culture for every new volume of the respective media. RESULTS: The results showed that culture media composed of milk whey without filtration supplied L. lactis its adaptation needs better than filtrated milk whey. Nisin titers, in milk whey without filtration (pH adjusted), was 11120.13 mg L^?1 in the second transfer, and up to 1628‐fold higher than the filtrated milk whey, 6.83 mg.L^?1 obtained in the first^t transfer. CONCLUSIONS: Biological processing of milk byproducts (milk whey) can be considered a profitable alternative, generating high‐value bioproducts and contributing to decreasing river disposals by dairy industries. Copyright © 2008 Society of Chemical Industry