Influence of dietary supplementation with dextrin or oligofructose on the hepatic redox balance in rats

We assessed the impact of oligofructose (OFS) and dextrin (DEX) as diet supplements on hepatic redox state. Rats were fed either a 10% OFS or a 10% DEX supplemented diet for 9 wk. In the DEX diet group, the levels of hepatic protein carbonylation were decreased by 63%. Total glutathione and reduced glutathione (GSH) contents were reduced in the OFS and DEX diet groups by around 20%. DEX supplementation significantly reduced oxidized glutathione (GSSG) levels resulting in a 33% increase in the GSH/GSSG ratio. The activity of the hepatic antioxidant enzymes was not changed by either OFS or DEX supplementation. OFS supplementation caused a decrease in serum levels of triglycerides (36%), cholesterol (24%), HDL (16%) and LDL (17%). DEX supplementation only reduced triglycerides (32%) and urea (22%). Both diets increased serum levels of acetate by fivefold and propionate by twofold, but DEX diet decreased butyrate levels by 75%. Due to their different composition/structure these two dietary fibers affected metabolism in different ways. Diet supplementation with 10% DEX can potentially improve host health, by protecting the liver from protein carbonylation and by improving GSH/GSSG ratio and diet supplementation with 10% OFS can improve the lipid profile.     

Effect of nitrogen fertilization on quality markers of strawberry (Fragaria × ananassa Duch. cv. Aromas)

BACKGROUND: Nitrogen is an indispensable element for fruit metabolism and low or excessive N levels can affect the accumulation of the most important components that contribute to the flavour and aroma of the fruit. Among them, sugars, acids and volatile compounds can be considered quality markers. The objective of this study was to evaluate the effect of N fertilization on these quality markers of the fruit at two harvest dates. RESULTS: Strawberry plants were grown in a hydroponic system and N was applied as Ca(NO₃)₂ at concentrations of 0.3, 3 and 6 mmol L^?1 in the nutrient solution. Total soluble solids, soluble carbohydrates, amino acids and organic acids and volatile compounds of the fruit were analyzed. The fruits produced at 3 and 6 mmol L^?1 N had higher contents of esters, soluble carbohydrates and amino acids. The hexanal content increased with the 6 mmol L^?1 dose. The effect of fertilization was more marked at the second harvest date. CONCLUSION: The availability of N in strawberry plants affected the accumulation of quality markers. The fruits expected to have the best flavour and aroma, with both high levels of soluble carbohydrate and esters and low levels of hexanal, were obtained with 3 mmol L^?1 nitrate in the solution. Copyright © 2009 Society of Chemical Industry     

Triazole fungicide degradation in peaches in the field and in model systems

The degradation of five triazole fungicides (cyproconazole, hexaconazole, penconazole, propiconazole, tebuconazole) in peaches was evaluated in field studies to establish whether at the preharvest interval the residue levels were below the legal limit established in Italy. All fungicides, except propiconazole, showed higher residues than the legal limits because of their high stability. In fact, some did not decrease at all (cyproconazole, penconazole, tebuconazole), while others decreased only in part. The increasing weight of the fruit during growth was the main factor leading to an apparent decrease in pesticide levels on a weight for weight basis. The trials on model systems showed that co-distillation and sunlight photodegradation were the main mechanisms leading to a decrease in triazole levels. Although these fungicides are systemic, they did not enter the fruit and all residues were only present in the peel.     

丝纤维经有机试剂处理后理化性能的研究

丝纤维经10种不同试剂处理后,其膨化性、初始模量和断裂模量均发生了相应的变化,反映在溶解参数变化曲线上,都呈一定的规律性。     

On the nonisothermal melt crystallization kinetics of industrial batch crosslinked polyethylene

The chemical modification of commodity polymers such as polyethylene (PE) is a versatile synthetic approach for preparing materials that cannot be manufactured cost-effectively using conventional polymerization techniques. Aiming to improve PE character low contents of dicumyl peroxide (DCP), from 0% to 1.5% was added as crosslinker to an industrial batch (PEs mixture and additives). From tensile testing crosslinking provided higher elastic modulus most due to the restrained microstructure where XPEs macromolecular chains are interconnected also providing lower strain at break. Crosslinking effects on the nonisothermal melt crystallization rate (Cmax) and degree of crystallinity (Xc) were evaluated; Cmax increased with the cooling rates, whereas Xc increased upon DCP addition. The melt crystallization kinetics were thoroughly investigated applying Pseudo-Avrami, Ozawa, and Mo models. Ozawa failed to describe the crystallization most due to ignore the secondary crystallization and spherulites impingement at the end of crystallization while Pseudo-Avrami and Mo provided quite good fits. The activation energy was computed using Arrhenius' approach, crosslinked compounds presented higher energy consumption, whereas exception was verified for 0.5XPE which displayed the lowest energy and overall the best mechanical performance this is the most proper compound for industrial applications, such as packaging, and disposables as well as general goods.     

混凝土天棚辐射供冷的应用探讨

介绍了天棚混凝土辐射供冷的优势;分析了混凝土辐射供冷中天棚最大允许换热能力和室内空气参数的关系、天棚辐射换热量的比例;分析了新风除湿对混凝土天棚供冷的影响以及利用冷却塔进行天棚供冷的可行性。得出的结论对工程实际有很好的指导作用。     

General behaviour and effect of rigid and non-rigid end post in stainless steel plate girders loaded in shear. Part II: Extended numerical study and design proposal

After the deep analysis and evaluation of the experimental and numerical results obtained during the described experimental campaign [Estrada I, Real E, Mirambell E. General behaviour and effect of rigid and non-rigid end post in stainless steel plate girders loaded in shear. Part I: Experimental study. Journal of Constructional Steel Research 2005 [submitted for publication]], an extended numerical analysis in code ABAQUS [Hibbit, Karlsson and Sorensen Inc., ABAQUS/Standard, Version 6.3. User’s manual. Rhode Island (USA); 2002] has been carried out dealing with the evaluation of the postbuckling strength in stainless steel plate girders. Finally, a proposal of design expressions for predicting their ultimate shear capacity is made since current design specifications dealing with shear resistance included in Eurocode 3, Part 1-4 [European Committee for Standardisation. ENV 1993-1-4. Eurocode 3: Design of steel structures. Part 1.4: General rules—supplementary rules for stainless steel. Brussels; 1996] have been demonstrated to be overly conservative.Taking special attention of the material non-linearity and the rigid or non-rigid condition of the end post, specimens covering a wide range of slenderness and aspect ratios (a/d from 0.5 to 3.0) have been numerically tested. Austenitic and Duplex stainless steel grades, which are the most commonly used in construction, have been evaluated during the whole analysis development.Finally, a new design proposal based on the Rotated Stress Field model developed by Höglund [Höglund T. Shear buckling resistance of steel and aluminium plate girders. Thin-Walled Structures 1998;29(1-4):13-30], adequately adapted to the particular features of stainless steel is presented in order to reach a more optimum use of this relatively modern resistant material in construction.