Free vibration of partially supported piles with the effects of bending moment, axial and shear force

The pile parts above the soil and embedded in the soil are called the first region and the second region, respectively. The fourth order partial differential equations of both regions for free vibration of partially supported pile subjected to bending moment, axial force and shear force are obtained using the small-displacement theory and the Winkler model. It is assumed that the behavior of the material is linear-elastic, and that axial force along the pile length and modulus of subgrade reaction for the second region to be constant. Shear effect is included in the partial differential equations by the second derivative of the elastic curve function with respect to shear deformation. Natural circular frequencies and relative stiffness of the pile are calculated for non-trivial solution of linear homogeneous system of equations obtained due to the values of axial forces acting on the pile, the shape factors, and the boundary conditions of the pile with both ends free and both ends simply supported; the results are presented in graphs.     

High efficiency and reusability of iridium complexes adsorbed in montmorillonite clay on catalytic hydrogenation of imines

Heterogenised homogeneous catalytic hydrogenation of aldimines by removable and reusable immobilised iridium complexes on montmorillonite clay. This revised version was published online in July 2006 with corrections to the Cover Date.     

Winery grape-residue extract: Effects on quality and sensory attributes of cooked chicken meat

Sensory analysis, instrumental color, pH, and thiobarbituric acid reactive substances (TBARS) were determined on cooked chicken meat with and without grape seed extract during refrigerated storage. The effectiveness of extracts of winery grape residue from the grape varieties ‘Isabel’ and ‘Niagara’ were tested to evaluate their effectiveness at delaying lipid oxidation in cooked chicken meat and stored under refrigeration (4±1°C). The samples were aerobically and vacuum packaged and stored for 14 days. ‘Isabel’ grape extract (IGE) and ‘Niagara’ grape extract (NGE) proved effective at promoting oxidative stability when applied at concentrations of 40 or 60 mg of gallic acid equivalents (GAE)/kg, with results similar to the synthetic antioxidant butylated hydroxytoluene (BHT). The antioxidant efficiency of the extracts was highly dependent on the concentration used. The addition of grape-residue extracts combined with vacuum packaging proved to be a good method for increasing lipid stability in cooked chicken meat stored under refrigeration.     

Electricity production from twelve monosaccharides using microbial fuel cells

Direct generation of electricity from monosaccharides of lignocellulosic biomass was examined using air cathode microbial fuel cells (MFCs). Electricity was generated from all carbon sources tested, including six hexoses (d-glucose, d-galactose, d(−)-levulose (fructose), l-fucose, l-rhamnose, and d-mannose), three pentoses (d-xylose, d(−)-arabinose, and d(−)-ribose), two uronic acids (d-galacturonic acid and d-glucuronic acid) and one aldonic acid (d-gluconic acid). The mixed bacterial culture, which was enriched using acetate as a carbon source, adapted well to all carbon sources tested, although the adaptation times varied from 1 to 70 h. The maximum power density obtained from these carbon sources ranged from 1240 ± 10 to 2770 ± 30 mW m⁻² at current density range of 0.76–1.18 mA cm⁻². d-Mannose resulted in the lowest maximum power density, whereas d-glucuronic acid generated the highest one. Coulombic efficiency ranged from 21 to 37%. For all carbon sources tested, the relationship between the maximum voltage output and the substrate concentration appeared to follow saturation kinetics at 120 Ω external resistance. The estimated maximum voltage output ranged between 0.26 and 0.44 V and half-saturation kinetic constants ranged from 111 to 725 mg L⁻¹. Chemical oxygen demand (COD) removal was over 80% for all carbon sources tested. Results from this study indicated that lignocellulosic biomass-derived monosaccharides might be a suitable resource for electricity generation using MFC technology.     

Levels of essential and toxic elements in Porphyra columbina and Ulva sp. from San Jorge Gulf, Patagonia Argentina

Baseline concentration levels of As, B, Ca, Cd, Cr, Cu, Co, Fe, Mg, Mn, Mo, Ni, P, Pb, Se, V, and Zn were determined for Porphyra columbina and Ulva sp. collected from three locations along San Jorge Gulf, in Patagonia Argentina. Elements were quantified by inductively coupled plasma-optical emission spectrometry, with the exception of lead and cadmium in some samples which were determined by electrothermal atomic absorption spectrometry. Three stations with different exposure degree to human activities, Bahía Solano, the mouth of Arroyo La Mata stream and Punta Maqueda, were selected as sampling points. The results showed a wide range of metal retention capacity between the two studied species. Regarding the levels of pollutants found in the researched sites, Punta Maqueda seemed to be less influenced by anthropogenic activities than the other two sites except for Cd. Taking into account their toxicities seasonal variations in Pb and Cd levels were studied in both algae in Punta Maqueda. Maximum concentrations of Cd (9.8 microg g(-1) dry wt.) were observed in P. columbina during winter, and maximum levels of Pb (0.82 microg g(-1) dry wt.) were detected in Ulva sp. during summer. Legislative and health safety aspects were evaluated for Cd and Pb.     

Lipid and protein deterioration during the chilled storage of minced sea salmon (Pseudopercis semifasciata)

Sea salmon is a very appreciated seafood. The aim of this work was to analyze changes in lipid and protein fractions of minced muscle during chilled storage (1 ± 1 °C). Lipid oxidation was important during the first 6 days of storage according to 2‐thiobarbituric acid (TBA) values determined, decreasing mainly ω3 22:6 fatty acid content. Lipid hydrolysis was evident after 9 days of storage. Interaction compounds between oxidation products and other cellular components were analyzed by fluorescence measurements. The results obtained showed evidence of the formation of interaction products involved, mainly polar components such as proteins. Decreases in myosin and actin thermal stability and myosin denaturation were recorded by differential scanning calorimetry. Solubility of total and myofibrillar proteins decreased after 6 days of storage. The electrophoretic profile of soluble fractions showed an increase in the intensity of bands corresponding to low‐molecular‐weight polypeptides and a decrease in high‐molecular‐weight species. Available lysine content did not change during chilled storage. Copyright © 2007 Society of Chemical Industry     

Effect of the shield gas,working angles and displacement angles on the characteristics of fillet joints obtained via GMAW using a high-strength microalloyed steel

ABSTRACT

Fillet joints are one of the most commonly used joints in various industries, in particular for agricultural machinery. However, the complexity of the pieces that require welding often makes accessibility difficult for the welder for this kind of joint, and working and displacement angles are important aspects to be evaluated. In addition, in the GMAW process, the use of the Ar-20%CO₂ mixture as the shield gas has increased at the expense of 100% CO₂, generally requiring an adjustment of the electrical parameters. On the other hand, the incorporation of new materials with higher strength also involves optimizing the welding procedure. The aim of this study was to evaluate the effect of two shield gases (Ar-20% CO₂ and 100% CO₂), three working angles (30, 45 and 60°) and two displacement angles (45° using the push technique and 60° using the pull technique) on the dimensional characteristics of the seam and the mechanical strength of the fillet joint from a microalloyed steel with high strength welded using GMAW. The highest levels of penetration corresponded to the test specimens welded using the pull technique and with CO₂. The over thickness was smaller for conditions with the push technique and the gas mixture. The microhardness of the weld metal, for a similar working angle, was higher for the gas mixture in all cases. Indices of acceptability were developed, which graded geometric aspects and these were compared with the mechanical properties obtained on the welds, showing a good correlation.     

Global and specific migration of antioxidants from polypropylene films into food simulants

Global migration and specific migration of antioxidants (AOs--Irgafos 168 [tris(2,4-di-tert-butylphenyl) phosphite], Irganox 1076 [octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl-propionate], and Hostanox SE2 (distery thiodipropionate)--from polypropylene (PP) films into food simulants (water, 3% acetic acid, 95% ethanol, olive oil, and heptane) were studied. Films (50, 100, and 200 microns thick) were exposed to simulants at temperature-time conditions simulating migration under retorting and long-term storage. Global migration into aqueous simulants was independent of film thickness and conditions of exposure, so it seems as if the migration process was limited to the dissolution of migrants on the contacting surface. Global migration to fatty food simulants was dependent on simulant, conditions of exposure, and in some cases film thickness. Specific AO migration was analyzed from dry residues obtained from global migration analysis. Migration of AOs into aqueous simulants was below the detection limit (0.01 mg/dm2). Migration into fatty food simulants was dependent on the simulant. The extractive power of simulants was similar to that observed in global migration studies. Specific migration into heptane was independent of the polymer mass, though dependent on the thickness. Migration into ethanol was dependent on both mass and thickness. A theoretical discussion about the controversial effect of thickness on migration results, based on the kinetics of the process, is presented.