Microstructure and Compression Strength of Novel TRIP‐Steel/Mg‐PSZ Composites

Novel composites on basis of austenitic stainless TRIP‐steel as matrix with reinforcements of Mg‐PSZ are presented. Compact rods were produced by cold isostatic pressing and sintering, square honeycomb samples by the ceramic extrusion technique. The samples are characterized by optical and scanning electron microscopy before and after deformation, showing the microstructure and the deformation‐ induced martensite formation. The mechanical properties of samples with 5 vol% zirconia are superior compared to zirconia‐free samples and composites with higher zirconia contents in terms of bending and compression tests. The honeycomb samples exhibit extraordinary high specific energy absorption in compression.     

Effects of sprayer configuration on efficacy for the control of scab on crabapple using electron beam analysis

Foliar diseases like apple scab result in significant economic losses to growers each year. Assessment in past studies involved only macroscopic disease ratings. More complete knowledge of the fate and behavior of fungicide has been needed to reduce pesticide use with less off‐target contamination. Field studies were conducted in a production nursery for over 4 years. A moderately susceptible cultivar of ornamental crabapple, Malus spp. cv “Candied Apple”, was sprayed with a fungicide using two sprayer/nozzle configurations. The fungicide used in this study was Mankocide, combination of Cu(OH)₂ and mancozeb that permitted electron beam analysis (EBA) identification based on the presence of Cu, MN and Zn in the molecule and formulation. EBA was conducted using a cold field emission scanning electron microscopy and energy dispersive x‐ray microanalyzer. Fresh leaf samples were placed on sticky stubs after each fungicide treatment. The presence or absence of fungal conidia and fungicide residue were measured. EBA permitted direct visualization and identification of the pathogens, morphologically, and chemical characterization of fungicide present. EBA was useful to quantify disease control related to fungicide coverage, sprayer configuration and treatment efficacy. SCANNING 31: 24–27, 2009. Published 2009 by Wiley Periodicals, Inc.     

Temperature Dependence of the Hardness of Nanocrystalline Titanium Dioxide

Vickers hardness of nanocrystalline ( N -) TiO₂ was measured in the temperature range 25° to 1200°C and it was compared with that of polycrystalline ( P -) TiO₂ in the same temperature range. N -TiO₂ showed a lower hardness than P -TiO₂ at temperatures up to 800°C which resulted in the lack of indentation crack traces for N -TiO₂ presumably implying more plasticity.     

Development and characterization of a biocompatible OH-modified copolymer based on polyurethane

Different polyurethanes were synthesized by varying the diol as well as the diisocyanate components and chain extenders. Polyurethanes with OH-groups were obtained by photo- and thermoinitiation of the radical polymerization of hydroxy alkyl acrylates in the presence of the polyurethanes. The polymers were evaluated with respect to their biocompatibility by measuring the cell spreading, the rates of DNA- and protein synthesis and the swelling behaviour. The differences in the surfaces and the bulks between the selected basic polyurethane and the functionalized modification were determined and characterized by XPS, FTIR-ATR and ¹³C-FT-NMR-spectroscopy. The mechanical data of Tecoflex EG 60D® and Pellethane 2363–80AE® were compared with the data of the synthesized polyurethanes.     

Membranen in der Verfahrenstechnik

Membranes in chemical engineering . In the last 10 years membranes and membrane processes have evolved from a useful laboratory tool to an industrial product of significant technical and commercial impact. In some applications membrane processes have today not only replaced some conventional separation procedures in the chemical process industry, because they are often more economical and yield better quality products, but they have also successfully been utilized to solve mass separation problems where conventional procedures failed or are too expensive. This contribution discusses the state of the art of membranes and membrane processes as well as their major applications, with the main emphasis being placed on more recent developments.     

Heat transfer between particle beds and submerged surfaces

Theoretical modelling of heat transfer to particle beds comprises two sequential steps: transfer from the heating surface to contacting particles followed by transfer to the interior of the bed. Two different limiting case can be formulated for the second step: unmixed and homogeneously mixed bed. In the case, heat is transferred gradually via a repeated sequence of heat transfer in the gap between adjacent particles and conduction in the particulate material. In the second case, heat is transferred to the interior of the bed by mixing of particles which have previously attained the temperature of the heating surface. On the other hand, the mixing motion maintains a homogeneous lower temperature throughout the bed. Theory predicts a significant and easily measurable difference in the behaviour of heat transfer coefficients for the two regimes at long contact times t: unmixed beds ∝ $$ \sqrt t $$ and homogeneously mixed beds ∝ 1/t. For short times t, both regimes show the same behaviour, namely of t. From a theoretical standpoint, it makes sense to differentiate further between the behaviour patterns of unmixed beds: at long times t, instantaneous heat transfer coefficients are independent of heat transfer form the heating surface to adjacent particles. Comparison with experimental result from literature shows that the derived models, which are consistent, are suitable for describing the heat transfer from submerged surfaces to unmixed and mixed beds of particles.     

Description and comparison of a new cleaning method of diatom frustules for light and electron microscope studies

A general review is made of some of the methods commonly used by phyto-planktologists in preparing and cleaning siliceous diatom frustules for light and electron microscopy. A comparatively simple and safe method using potassium persulphate and oven heating is described. Procedures for rinsing and mounting field samples are also included.     

Analysis of the temperature dependence of the fracture stress of sharp notched bending specimens of a structural steel with respect to intermediate transitions

The flow and fracture stresses, σ_y^g and σ_f^g (δ = crack tip displacement), of sharply notched bending specimens of a structural steel U St 37-1 are measured in the temperature range from full scale to small scale yielding. The best adaption of the experimental results for σ_f^g is obtained by a curve which exhibits an intermediate transition, i.e. which follows in a temperature range between an upper, T_tM¹ and a lower, T_tl¹, transition temperature to the curve σ_y^g(T) for the flow stress with a constant δ = δ₁. This transition corresponds to that of the slip to the twin nucleated fracture. Two analyses [3,5] according to the local fracture stress, σ_f^*, concept show that the amount and the temperature dependence of σ_f^* are somewhat different for both methods, but that both exhibit an increase of σ_f^* in the transition range. It is concluded that each transition in the nucleation mode of the fracture is connected with such a transition in the fracture stress. It may, however, become indistinct or even be covered by the scatter of the experimental points.