Investigations of gas-particle-lance flows at high velocity for the injection of solid in melting baths

For the injection of gas and solid into molten masses using lances the situation at the lance outlet is a boundary condition for the mixing in the melting bath and therefore an important parameter for the energy and mass exchanges which take place there. In the scope of the main research programme of the Deutsche Forschungsgemeinschaft named “Mischung mit Energie-und Stoffumsatz in schmelzmetallurgischen Systemen”, a mathematical model is to be developed at the Institut für Energieverfahrenstechnik der Technischen Universität Clausthal, which should make it possible to calculate the situation at the outlet of a lance operating with gas and solid, using operational and geometrical parameters (pressure at lance intake, amount of solid, length and diameter of lance) which can be freely chosen.     

Optimization of planar Be-doped InGaAs VCSEL's with two-sidedoutput

Threshold current, output power, wall-plug efficiency and operating voltage of epitaxially grown InGaAs-AlGaAs planar vertical-cavity surface-emitting lasers (VCSEL's) are strongly influenced by the electrical and optical properties of the p-doped Bragg reflector. Here we study in some detail the dependence of output behavior on the composition, interface grading, and modulation doping of the Be-doped AlGaAs-GaAs Bragg reflector. Using optimized p-doped mirrors VCSEL's with low threshold current densities of 300 A/cm² , low driving voltages of 1.6 V and high wall-plug efficiencies of 17.6% are obtained. Transverse single-mode emitting devices show a record low emission linewidth of 30 MHz and a linewidth-power product of 2.2 mW·MHz     

Mechanical damage to Gram-negative bacteria by surface plating with the Drigalski-spatula technique

Colony counting by spreading bacterial suspensions on plating media by various techniques is of general concern. Comparative studies between hand plating (Drigalski-spatula technique) for different time intervals and spiral plating resulted in significant differences in colony counts. Lower counts of Gram-negative bacteria were obtained by using hand plating for more than 10 s, compared with short time hand plating (5 s) or spiral plating. Colony counting of Gram-positive bacteria showed no differences between both techniques. Further characterisation of Escherichia coli cells spread with the Drigalski-spatula technique by electron microscopy revealed a large number of damaged cells compared to control samples. The data clearly shows that the mechanical forces during hand plating are sufficient to damage E. coli cells.     

Conjugated Polymers of Intrinsic Microporosity (C‐PIMs)

Conjugated microporous polymers (CMPs) have shown great potential for energy and environmental issues, however, poor solubility and processability of most of these materials limit their applications. Herein, a range of linear conjugated polymers of intrinsic microporosity (C‐PIMs) is reported, combining for the first time the properties of conjugated microporous polymers, such as tunable electronic properties and compositional variation, with those of linear polymers of intrinsic microporosity (PIMs) allowing for solution processability and film formation. These soluble materials have a number of potential applications, for example as components in devices where large, porous interfaces are combined with extended electronic conjugation.     

Concentration and bioaccumulation of dechlorane compounds in coastal environment of northern China

Dechloranes, including Dechlorane Plus (DP), Mirex (Dechlorane), Dechlorane 602 (Dec 602), Dechlorane 603 (Dec 603), and Dechlorane 604 (Dec 604), were determined using GC-MSD for water, sediment and oyster samples collected at 15 sampling sites near the Bohai and Huanghai Sea shore area of northern China in 2008. DP and Mirex were detected in most water, sediment, and oyster samples, which indicated widespread distribution of these two compounds. The mean concentrations in water, sediment and oyster samples, respectively, were 1.8 ng/L, 2.9 ng/g dry weight (dw) and 4.1 ng/g wet weight (ww) for total DP, and 0.29 ng/L, 0.90 ng/g dw, and 2.0 ng/g ww for Mirex. Dec 602 and Dec 603 were not detected in water but in small portions of the sediment and oyster samples, showing a low level of contamination by these two chemicals in the region. Strong and significant correlations were found between total DP and Mirex concentrations in water, sediment and oyster samples, probably suggesting similar local sources of these two chemicals. Dec 604 was not found in any samples. The biota-sediment accumulation factor (BSAF) of DP, Mirex, and Dec 602 declined along with the increase of their logarithm of octanol-water partition coefficients (log Kow), possibly indicating that compounds with lower log Kow (like Mirex and Dec 602) accumulated more readily in biota. The mean fractional abundance of syn-DP (fsyn) was 0.34 in water samples, a value lower than that in Chinese commercial mixture (0.41), while the mean fsyn for surface sediment (0.44) and oyster (0.45) samples were higher than technical values. Enrichment of syn-DP in oyster was in agreement with previously reported findings in Great Lakes fish. Enrichment of syn-DP in marine surface sediments, however, is contrary to data reported for fresh water sediments. To our knowledge this is the first report of Dec 602, Dec 603, and Dec 604 in a marine environment and also the first report of Dechloranes in marine biota.     

Development of a model for the simulation of the transfer of surface structure in the temper-rolling process

In the temper rolling process the effect of transferring the roll-surface structure to the steel sheet is purposely used to adjust a defined sheet-surface structure required for further processing. At the moment four different texturing techniques (SBT, EDT, EBT, LT) are available for the production of specified roll-surface structures; these techniques are based on two fundamental mechanisms; plastic deformation and local melting. The objective of the investigation presented in this paper is to analyze the transfer behaviour specific to the texturing technique used and, in addition to that, to develop a model for the simulation of these transfer characteristics. For this purpose in the first part the results of a comparative study on the basis of rolling tests on an industrial temper mill are presented. These results do not only point out the basic transfer mechanisms – penetration processes and reverse extrusion phenomena – but beyond that also lead to an explanation of the transfer behaviour specific to the texturing systems by the application of similarity numbers (substitute profile model). Possible reasons for the different transfer behaviour are on the one hand wear effects and on the other hand process-induced characteristics of the structure itself (e.g. isolated lubrication pockets). On the basis of these results in the second part a model is developed to simulate the transfer characteristics by the application of the finite element method (FEM).     

Profiles of four women. Health and human rights activists

This article briefly profiles four women physicians working for health and human rights around the world. Dr. Ruchama Marton, an Israeli psychiatrist and activist for peace in the Middle East, is a founder of Physicians for Human Rights/Israel. Dr. Jane Green Schaller is a US pediatrician whose 1985 trip to South Africa initiated her human rights involvement, which includes the founding of Physicians for Human Rights. Dr. Judith van Heerden, a primary care physician in South Africa, has worked for reform of prison health care, to establish hospice care, and, most recently, for acquired immune deficiency syndrome (AIDS) education for medical students. Dr. Ma Thida, the only physician not interviewed for this article, is currently held in a Burmese prison because of her work on behalf of the National League for Democracy. The profiles suggest the breadth of human rights work worldwide and are a testament to what physicians can do.