Application of the electrochemical microcapillary technique to study intergranular stress corrosion cracking of austenitic stainless steel on the micrometre scale

The electrochemical microcapillary technique was applied for the first time to study the electrochemical dissolution signals from single growing cracks due to stress corrosion cracking of thermally sensitised AISI 304 stainless steel in potassium tetrathionate solution. Potentiostatic current measurements on initiating cracks along grain boundaries were performed. Typical current signals of potentiostatic and potentiodynamic measurements consisted of a series of current peaks showing fast rise and exponential decay, sometimes interrupted by passive phases. The results indicate that stress corrosion crack growth is a discontinuous process of passive and active phases, which might be explained by the film rupture model.     

Surface-acoustic-wave pulse transducer

Short pulses of surface acoustic waves are launched efficiently by an inline assembly of several finger-pair interdigital transducers, which are connected to successive taps of an electrical delay line, where the electrical time lag between two taps is equal to the acoustic delay between corresponding transducers.     

Liquid phase formation in the system AlN–Al2O3–Y2O3. Part I: Experimental investigations

The liquid phase formation in the system AlN–Al₂O₃–Y₂O₃ was investigated via differential thermal analysis (DTA) combined with thermogravimetry (TG). For this purpose 17 samples covering a broad composition area of the quasi-ternary system were densified and heat-treated to achieve the equilibrium state. Melting temperatures were determined by DTA. SEM, EDX and XRD were used to study the phase assemblages and microstructures formed. The results were compared with thermodynamic calculations.     

Differential time course of angiotensin-induced AP-1 and Krox proteins in the rat lamina terminalis and hypothalamus

Binding to olfactory receptors is the first step in odorant and pheromonal recognition and discrimination. These receptors constitute one of the most important, although poorly known, families of neuronal receptors. In this study we used degenerated oligonucleotides and a RT-PCR approach to selectively amplify olfactory receptors in the nasal epithelium of the domestic pig Sus scrofa. Several combinations of oligonucleotide were tested and allowed the isolation of eleven different partial sequences belonging to the seven transmembrane olfactory receptor family. These receptors formed a separate family within the seven transmembrane receptor superfamily in pigs. Using the criteria of Ben Arie et al. [Ben-Arie N., Lancet D., Taylor C., Khen M., Walker N., Ledbetter DH., Carrozzo R., Patel K., Sheer D., Lehrah H. and North M., Hum. Mol. Genet., 3 (1994) 229-235], the 11 receptors described here can be classified into three known families and seven subfamilies (one known and six new).     

Densification behaviour of pure molybdenum powder by spark plasma sintering

Pure molybdenum was sintered with SPS under various temperatures, external pressures and heating rates. The microstructure of the specimens representing the different sintering conditions was investigated by classical metallographic methods. The relative density, the microhardness and the chord length distribution were measured. Linear shrinkage, depending on time or temperature, was calculated from piston travel, which was recorded during sintering process. These results show that the main part of consolidation takes place during fast heating up. The densification behaviour is controlled mainly by sintering temperatures and applied pressure. The molybdenum powder was successfully consolidated by SPS in very short times. A relative density of 95% was reached by sintering temperatures of 1600 °C and external pressure of 67 MPa.     

A parallel code for a self-consistent charge density functional based tight binding method: Total energy calculations for extended systems

We present a parallel version of a selfconsistent-charge density-functional based tight-binding (SCC-DFTB) method for total energy calculations and geometry optimizations of clusters and periodic structures. On single processor machines the SCC-DFTB method has been successfully applied to systems up to several hundred atoms with an accuracy comparable to sophisticated selfconsistent field density-functional theory (SCF-DFT) methods. The new parallel code allows to treat systems which are larger by an order of magnitude in reasonable time. The freely available ScaLAPACK and PBLAS libraries are used for linear algebra operations. We tested the scaling of our program for a realistic system (III–V semiconductor surface) with different sizes and give a short outlook on current applications.     

Total Volatile Organic Compounds (TVOC) in Indoor Air Quality Investigations*

Abstract The amount of volatile organic compounds (VOCs) in indoor air, usually called TVOC (total volatile organic compounds), has been measured using different definitions and techniques which yield different results. This report recommends a definition of TVOC referring to a specified range of VOCs and it proposes a method for the measurement of this TVOC entity. Within the specified range, the measured concentrations of identified VOCs (including 64 target compounds) are summed up, concentrations of non-identified compounds in toluene equivalents are added and, together with the identified VOCs, they give the TVOC value. The report reviews the TVOC concept with respect to its usefulness for exposure assessment and control and for the prediction of health or comfort effects. Although the report concludes that at present it is not possible to use TVOC as an effect predictor, it affirms the usefulness of TVOC for characterizing indoor pollution and for improving source control as required from the points of view of health, comfort, energy efficiency and sustainability.     

Monte Carlo calculation of the small sample reactivity effect

A monte Carlo method for the calculation of the reactivity effect of a small sample in a nuclear reactor is described. Particle histories are started within the sample. Therefore, it is not necessary to enter the sample from outside with a small probability. After leaving the sample, the histories are terminated at some distance from the sample site using pre-calculated results of the unperturbed reference system. The influence of some approximations is diminished because these pre-calculated results are used only far away from the region of interest. Some numerical results show the efficiency of the method. The method is fast and can also be used at rather small and slow computers.