预变形结合人工时效对Al-Mg-Si合金力学性能的影响

研究预变形结合人工时效处理对AA6060铝合金强度和韧性的影响。对经过均匀化热处理和挤压加工的AA6060铝合金进行固溶处理,然后对材料实施0-10%的预变形并再进行时效处理或者在人工时效过程中进行同步变形。通过对不同时效处理后的合金的显微硬度和拉伸性能分析,发现预变形对材料的时效行为和力学性能有显著影响,它可以使合金的时效速度明显加快。比较预变形和同步变形对人工时效的影响发现,同步变形结合人工时效可以使该合金在更短的时间内得到更好的力学性能。对两种变形对时效行为的影响机理进行了探讨。     

Fatty Acid Composition of Selected Fresh Water Gammarids (<Emphasis Type="Italic">Amphipoda</Emphasis>, <Emphasis Type="Italic">Crustacea</Emphasis>): A Potentially Innovative Source of Omega-3 LC PUFA

The aim of this work was to estimate the content and composition of n-3 long chain polyunsaturated fatty acids in selected gammarid species commonly occurring in fresh waters of Central and Western Europe. Five gammarid species were investigated, two native, one old invader consider as semi-native and two Ponto-Caspian species invading the area in the last decade. Lipid content of evaluated species ranged from 75 to 130 g kg⁻¹ of dry weight. Significant amounts of n-3 LC PUFA were found in the lipid fraction of analyzed gammarids 11–23% of total fatty acids, especially in the Ponto-Caspian species. The main n-3 fatty acid was EPA—up to 16% of total fatty acids. The ratio of n-6 to n-3 was nutritionally desirable, especially in the case of the Ponto-Caspian species. The results obtained and growing biomass of gammarids observed in fresh waters of Central and Western Europe, as well as the rapid depletion of sea fish communities leads us to the idea that these gammarids might be considered as a innovative source of n-3 LC PUFA for nutritional, pharmaceutical and animal feeding purposes.     

Swelling and mechanical behavior of ionized poly(acrylamide-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">N,N</Emphasis>’-diethylacrylamide) gels in water/acetone mixtures and in water at various temperatures

Summary Ionized networks of random copolymers of acrylamide (AAm) and N,N’-diethylacrylamide (DEAAm) (mole ratios of x_AAm/x_DEAAm=1/0,0.75/0.25,0.5/0.5,0.30/70,0.15/0.85,0/1) with various amounts of ionic comonomer-sodium methacrylate (MNa) (mole ratios to all monomers x_MNa=0.0,0.025,0.05) and crosslinker – N,N’-methylenbisacrylamide (MBAAm) were prepared at high dilution in water. Their swelling and mechanical behavior was investigated in water at various temperatures (from 10 to 90 °C) and in water/acetone (w/a) mixtures at room temperature. For some copolymers the transition region from expanded to collapsed state was observed at critical concentration of acetone, a_c, in w/a mixtures or at critical temperature, T_c, in water. It was found that with increasing content of DEAAm component in copolymers the a_c values increase; the similar increase was observed with increasing x_MNa. Neat PDEAAm and copolymers with the highest DEAAm content exhibit temperature transition; both increasing amount of AAm and charges bound on the chains (x_MNa) in copolymers shifts the T_c temperatures to higher values very efficiently (for more than 20 °C).     

Female presence during postejaculatory interval facilitates penile erection and 22-kHz vocalization in male rats.

During the postejaculatory interval (PEI), male rats exhibit prolonged immobility, 22-kHz vocalization, and penile erections. To test whether females modulate these behaviors, females were removed after the first or second ejaculation or left in the test chamber. Female presence during the PEI delayed exploratory behavior and facilitated vocalization and erection. Female stimulation of vocalization is consistent with the hypothesis that vocalization has a communicative function, not just a thermoregulatory one. The timing of the effect of females on erection suggests that males are sexually arousable well before they resume copulation. Therefore, erection may be better than vocalization as an indicator of the male's sexual refractoriness. The findings also challenge the conventional view that the PEI comprises absolute and relative sexual refractory periods marked, respectively, by the presence and absence of 22-kHz vocalization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced Carbon Diffusion in Austenitic Stainless Steel Carburized at Low Temperature

Austenitic stainless steel AISI 316L was carburized by a novel, low-temperature gas-phase process. Using a calibrated scanning Auger microprobe (SAM) analysis of cross-sectional specimens under dynamic sputtering, we determined the fraction–depth profile of carbon. The profile is concave—very different from the shape expected for concentration-independent diffusion—and indicates a carbide-free solid solution with carbon levels up to 15 at. pct and a case depth of ≈30 μm. A Boltzmann–Matano analysis with a careful evaluation of the stochastic and potential systematic errors indicates that increasing levels of carbon significantly enhance carbon diffusion. For the highest carbon level observed (15 at. pct), the carbon diffusion coefficient is more than two orders of magnitude larger than in dilute solution. The most likely explanation for this strong increase is that carbon-induced local expansion of metal–metal atom distances, observed as an expansion of the lattice parameter, reduces the activation energy for carbon diffusion.     

Swelling and mechanical behavior of charged poly(<Emphasis Type="Italic">N</Emphasis>-isopropylmethacrylamide) and poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) networks in water/ethanol mixtures. Cononsolvency effect

Summary Swelling and mechanical behavior of negatively (ionic comonomer-sodium methacrylate) and positively (ionic comonomer-(2-acrylamidoethyl)trimethyl ammonium chloride) charged networks of poly(N-isopropylmethacrylamide) (PIPMAm) and poly(N-isopropylacrylamide) (PIPAAm) was investigated in water/ethanol mixtures at room temperature. Strong cononsolvency effect was observed for uncharged and negatively charged gels of both systems; while for neat solvents high degree of swelling Q was observed, for solvent mixtures pronounced minima in swelling were found. Swelling minima are connected with the coil-to-globule transition of network chains and their characteristic parameters-concentration of ethanol at the minimum, c_eth,m, and corresponding swelling degree, Q_m, were determined. With increasing amount of negatively charged ionic comonomer the minimum in swelling shifts to higher c_eth,m values and Q_m increase. On the other hand, positively charged networks of both systems exhibit roughly constant Q values practically independent of solvent mixtures compositions. For all four systems it was found that mechanical behavior is predominantly determined by the degree of swelling regardless of charge concentration.     

Optimal Design of Trusses Under a Nonconvex Global Buckling Constraint

We propose a novel formulation of a truss design problem involving a constraint on the global stability of the structure due to the linear buckling phenomenon. The optimization problem is modelled as a nonconvex semidefinite programming problem. We propose two techniques for the numerical solution of the problem and apply them to a series of numerical examples.     

Efficient waste-to-energy system as a contribution to clean technologies

This paper deals with the problem of efficient energy utilization in the field of thermal processing of waste (waste-to-energy). An up-to-date incineration plant cannot be considered as only waste disposal facility. The waste combustion (incineration) processes are accompanied by release of large amount of energy, that shall be effectively utilized (e.g. steam production and its export to consumers, power generation, cogeneration). In addition to the main purpose of incineration, i.e. treating the specified amount of waste, waste-to-energy systems are able to some extent substitute conventional energy production plants fired by fossil fuel and thus to contribute to solving global environmental problems. For example, methodology presented in Reference Document on the Best Available Techniques for Waste Incineration (BREF) can be used for assessment of plant performance from the view of energy utilization. This approach is based on evaluation of criterion Plant Efficiency. An existing incineration plant has been evaluated and results are presented and discussed. In the future, it has been expected that evaluation like this will be obligatory for every plant. The arrival of more and more sweeping environmental limits represents a driving force for retrofit. At the same time maximum heat recovery and efficient energy utilization should be required. Influence of different operational modes (type of waste incinerated, combustion temperature, air-preheating etc.) and lay-out of heat recovery system (e.g. cogeneration) on plant performance has been investigated. A mathematical model based on combination of basic auxiliary operations and simple thermodynamic models of heat engines has been created with the aid of a specific computational tool. Its conception is based on both requirements and experience coming from industry. The most serious problem of effectively running incineration plants consists in economical utilization of energy produced. Examples of integration into existing energy systems are shown and discussed. An erratum to this article can be found at