Calculation of Diffusion-limited Growth of Hg1−x Cdx Te Epilayers on CdTe from Te-rich Melts by Step-Cooling LPE

Calculations of layer thicknesses and composition profiles in Hg_1−xCd_xTe layers on CdTe substrates for the growth from Te-rich melts have been carried out for liquidus temperatures of 460 °C, 480 °C, and 500 °C. This has been made on the basis of the multicomponent diffusion model of SMALL and GHEZ and the solid-liquid phase relation of BRICE . It could be shown that growth velocity increases only slightly with rising liquidus temperature. On the other hand, the interdiffusion velocity of Hg and Cd in the solid increases remarkably at a higher temperature. Therefore, to get layers with a constant x-value a higher supersaturation of the melt is necessary. The x-value decreases with rising supercooling by about 0.003 K⁻¹. To demonstrate the thermodynamically and kinetically advantageous properties of CdTe as substrate material, comparative calculations for a “hypothetical” HgTe substrate have been involved.     

Spatial Instability Of Two-Phase Mixing Layers

The initial stage of liquid atomization by a fast gas stream is considered by means of spatial stability analysis of two–phase shear layers. We solve the viscous linear stability problem for parallel flow modelled by error–function profiles. The unstable modes known from temporal theory are recovered in the convectively unstable case for fluid properties close to the air/water system. The most unstable wavelength depends only weakly on the absolute velocity relative to the laboratory system. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

MHD turbulence in a channel with spanwise field

We study turbulent channel flow of an electrically conducting liquid with a homogeneous magnetic field imposed in the spanwise direction. The Lorentz force is modelled using the quasistatic approximation. Direct and large–eddy simulations are performed for hydrodynamic Reynolds numbers Re=10000 and Re=20000 and the Hartmann number varying in a wide range. The main effect of the magnetic field is the suppression of turbulent velocity fluctuations and momentum transfer in the wall–normal direction. Comparing the results from direct and large–edddy simulations we show that the dynamic Smagorinsky model accurately reproduces the flow transformation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dmitrij Ivanovič Mendeleev (1834–1907): Zum 100. Todestag

The 100th anniversary of death of Mendeleev is occasion for us to appreciate live and work of this great scientist whose name is inseparable from the periodical system of elements and who accomplished pathbreaking benefits not only in the chemical field.     

Protein identification based on matrix assisted laser desorption/ionization-post source decay-mass spectrometry.

Due to its very short analysis time, its high sensitivity and ease of automation, matrix-assisted laser desorption/ionization (MALDI)-peptide mass fingerprinting has become the preferred method for identifying proteins of which the sequences are available in databases. However, many protein samples cannot be unambiguously identified by exclusively using their peptide mass fingerprints (e.g., protein mixtures, heavily posttranslationally modified proteins and small proteins). In these cases, additional sequence information is needed and one of the obvious choices when working with MALDI-mass spectrometry (MS) is to choose for post source decay (PSD) analysis on selected peptides. This can be performed on the same sample which is used for peptide mass fingerprinting. Although in this type of peptide analysis, fragmentation yields are very low and PSD spectra are often very difficult to interpret manually, we here report upon our five years of experience with the use of PSD spectra for protein identification in sequence (protein or expressed sequence tag (EST)) databases. The combination of peptide mass fingerprinting and PSD and analysis described here generally leads to unambiguous protein identification in the amount of material range generally encountered in most proteome studies.     

Solutal Marangoni convection in a Hele–Shaw geometry: Impact of orientation and gap width

The European Physical Journal Special Topics - We study Marangoni roll cell convection in a ternary mass transfer system composed of cyclohexanol, water and butanol (transferred species) placed in...     

Thermodiffusion and Morphological Stability in Convectionless Crystal Growth Systems from Melts and Melt-Solutions

Crystal growth experiments of multicomponent systems under microgravity require an exact analysis of the diffusion phenomena in the nutrient fluid phase. The contribution of the Soret effect to the transport and distribution of matter in a convectionless casting arrangement for shaped crystal growth and in THM melt-solution zones have been investigated. Some semiconductor systems were analysed from experimental (Bi_1-xSb_x mixed crystals) and theoretical (PbTe, InP, GaAs, CdTe compounds) point of view. The criterion for constitutional supercooling was correspondingly modified. It has been distinguished between associated (AIV BVI, AII BVI) and dissociated (AIII–BV) melt-solutions, containing different species of diffusion (molecules or atoms, respectively).     

Patterned turbulence in spatially evolving magnetohydrodynamic duct and pipe flows

Laminar-turbulent transition in spatially evolving magnetohydrodynamic pipe and duct flows is investigated numerically. The results are in good agreement with the classical 1937 experiments of J. Hartmann and F. Lazarus. It is found that the recently discovered flow regimes with turbulent spots near sidewalls are realized in spatially developing flows and must be detectable in experiments.