Degradable silver-based alloys

Noble metals solved in iron implants are effective cathodes, which can suit to accelerate the corrosion rate of the base material. In terms of its antibacterial behavior as well as lower costs in comparison with gold or platinum, silver seems to be an attractive candidate to adapt the corrosion rate of implants to the medical requirements. However, the degradation of silver in human bodies is a time-consuming process, and is controversially discussed due to the unknown long-term effect of silver on the human organism. Alloying silver with chemical elements less resistant to corrosion in aqueous mediums, particularly, in simulated body fluid, can improve the degradability of silver. Therefore, the current study addresses the design of adapted silver alloys exhibiting improved degradability in comparison with pure silver. Pure silver and binary silver alloys containing silicon, magnesium and calcium are studied in terms of their microstructure, open-circuit potential and degradation rate.     

Chemikalienfreie Bekämpfung von Holzschädlingen durch dielektrische Erwärmung mit Radiowellen und Mikrowellen

Thermal pest control requires long treatment times due to the low thermal conductivity of wood and may lead to the formation of cracks. Here, the thermal treatment with radio waves as well as microwaves has been studied. The direct dielectric heating has the advantage of a good homogeneity. The obtained temperature profiles for radio waves were more homogeneous compared to microwaves. Detailed studies showed that elimination of pests was not related to the application of the electromagnetic field itself, but due to the temperature increase.     

Stocking wild adult Florida largemouth bass (Micropterus salmoides floridanus): An additional fish management tool

Stocking of largemouth bass is an important management tool for fish management. The stocking of hatchery‐produced fingerling or advanced‐fingerling bass to supplement bass year‐classes, however, has exhibited varying success. Utilizing a different approach, a multiyear stocking programme using wild adult largemouth bass was initiated at the Harris Chain of Lakes (3800 ha Lake Griffin; 1811 ha Lake Dora) in central Florida. Wild adult bass (24 781 fish), ranging in size from 200 mm total length (TL) to over 600 mm TL, were stocked in Lake Griffin (13 932 fish) and Lake Dora (10 849 fish). One month after stocking, the number of stocked bass caught in electrofishing catches in Lake Griffin and Lake Dora was ~10% and 22%, respectively. Estimates of mortality were similar to the native largemouth bass, although the movement of stocked fish into other connecting water bodies was extensive. For the Lake Griffin/Lake Dora stocking programme, bass were transferred at a cost of $10.09–19.89 per fish, depending on how the costs of the project are calculated ($250 000 for just the capture and transport of the fish vs. $492 775 for the total project). Considering only capture and transport costs, conservative benefit/cost ratio estimates would be $1.77/$1.00 spent for replacement and $1.85/$1.00 spent recreational costs, although the benefit/cost ratios could exceed $10/$1. Based on the present study, stocking wild adult largemouth bass is a cost‐effective tool for managing largemouth bass.     

Dynamic viscosities of pure tin and Sn-Ag,Sn-Cu,and Sn-Ag-Cu eutectic melts

The dynamic viscosities of the melts of pure tin and eutectic Sn-Ag, Sn-Cu, and Sn-Ag-Cu alloys are studied in heating followed by cooling, and the maximum heating temperature was 1200°C. An irreversible decrease in the viscosity is found in the temperature range 800–1000°C in the polytherms of all melts. This finding is related to the loss of a local order in a melt and can be used to develop temperature regimes for the production of lead-free solders.     

Cognitive skill acquisition and transfer in younger and older adults.

The acquisition of cognitive skills often depends on 1 of (or a combination of) 2 processes, the execution of an algorithm, and the retrieval of problem instances. This study examined the effects of age and repetition of problem instances on the production and verification of solutions to 2 serially presented sets of alphabet arithmetic problems. Analyses of the parameters derived from power-function fits for individuals revealed age differences favoring young adults in improvement span, learning rate, and asymptote. For both age groups, the beneficial effects of repetitions on 1st-set response times were attributable to algorithmic speedup and to the retrieval of instances, whereas improvements in the speed of 2nd-set response times were attributable primarily to item retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Korrosionsverhalten binärer Magnesium‐Zink‐Legierungen in salzhaltigen Medien

Aluminum is a prevalent alloying element to improve the corrosion resistance of magnesium alloys. Recent investigations found out that alloying small amounts of zinc can decrease the corrosion rate of binary magnesium‐zinc alloys. Based on these results low‐alloyed MgZn‐alloys have been analyzed in gravimetric and electrochemical measurements using varied chloride containing media. It was detected that small amounts of zinc have positive effects on the corrosion behavior; in low as well as high concentrated sodium chloride solutions. The overall tendencies of the results from the gravimetric and electrochemical investigations can be correlated. This was underlined using micro‐tomography analyses.     

Surface tension and mass density of liquid Cu–Ge alloys

We report a study on the mass density and surface tension of liquid Cu–Ge alloys in the temperature range between the liquidus line and 1373 K. The experiments have been carried out by means of the sessile-drop method. The temperature dependences of both properties are given in terms of linear relations for all alloys under investigation. Both, density and surface tension show remarkable deviations from linear mixing: The density is increased, and the surface tension reduced due to Ge acting as surfactant. The composition dependence of the surface tension is discussed in terms of a simple compound formation model which is well able to relate the results to previous findings on the short-range order of the alloys under investigation.     

The dynamic viscosity of liquid Cu–Si alloys

The dynamic viscosity of liquid Cu–Si alloys is measured in the Cu-rich composition range (up to 40 at.% Si). The Arrhenius-law describing the temperature dependence of the viscosity holds for all alloys investigated. The viscosity isotherms, both experimental and from thermodynamic model calculations, show a broad maximum covering the homogenity ranges of the intermetallic phases. An interconnection of such findings with the atomic structure of the liquid alloys is briefly discussed.