Evaporation of single component viscous liquids in a metal falling film evaporator

Heat transfer for single component falling film evaporation has been investigated in a stainless steel single tube falling film evaporator. The tube had a heated length of 2,500 mm. Propylene glycol and cyclohexanol have been used as evaporating media. Liquid film running down the tube, is formed on the inner side of the tube. For the distribution of liquid two different devices were examined. Process equipment was operated in pump-around mode with the distillate being condensed and recycled. Results show that none of the available correlations for heat transfer in falling film evaporation is able to describe the results qualitatively as well as quantitatively. Using different film distribution devices, a significant influence of the Reynolds number for the transition from laminar to turbulent flow is seen. However, differences between experimental results and correlations in literature cannot be explained only by usage of different film distributions, in particular when the correlation is based on measurements with a different tube length. A model approach is presented for cyclohexanol as evaporating medium with a flat weir as film distributor.     

Accreditation of reference material producers: the example of IRMM's Reference Materials Unit

The potential approaches for third-party assessment of reference material producers are revisited and the activities of the Reference Materials (RM) Unit of the Institute for Reference Materials and Measurements (IRMM) to obtain accreditation to ISO Guide 34 and ISO 17025 are described. Accreditation was related to the Unit as all matrix RM activities of the institute are concentrated there. A management system was established that allows sufficient flexibility to be applicable to a wide range of RMs while being precise enough to ensure compliance with ISO Guides 30, 31 and especially 34 and 35. Accreditation was achieved in 2004 with independent scopes for testing and RM production and was confirmed and extended in 2005. The key aspects of the RM Unit's management system for RM production are presented. Presented at BERM-10, April 2006, Charleston, SC, USA     

Generalised acyclic edge colourings of graphs with large girth

The r-acyclic edge chromatic number of a graph G is the minimum number of colours required to colour the edges of G in such a way that adjacent edges receive different colours and every cycle C receives at least min{|C|,r} colours. We prove that for any integer r?4, the r-acyclic edge chromatic number of any graph G with maximum degree Δ and with girth at least 3(r-1)Δ is at most 6(r-1)Δ.     

Ternary Mn/Ge/Se anions from reactions of [Ba2(H2O)9][GeSe4]: synthesis and characterization of compounds containing discrete or polymeric [Mn6Ge4Se17]6- units

[Ba2(H2O)9][GeSe4] is suitable for the formation of novel M/14/16 anions [Mn6Ge4Se17]6- --discrete or linked in an as yet unprecedented porous network--with antiferromagnetically coupled Mn(II) centers and relatively small electronic excitation energies.     

Stable isotope-free quantitative shotgun proteomics combined with sample pattern recognition for rapid diagnostics

Mass spectrometry (MS) has become a powerful tool for the quantitative analysis of complex protein samples. A high-throughput strategy for the comparative analysis of multiple protein samples with high complexity becomes more and more important. Two strategies, spectral count and peak intensity, for label-free MS analysis of prefractionated complex mixtures have been described recently to be useful for quantitation. Here we compare both strategies for rapid and quantitative 1-D shotgun LC/MS/MS analyses of highly complex protein mixtures using silica-based monolithic columns. First, we validated linearity and sensitivity of these methods by spiking varying amounts of an internal standard protein in a complex plant protein extract. Secondly, quantitative data of proteins of Medicago truncatula nodules were visualized with independent components analysis using data either obtained from spectral count or peak integration performed with commercial software. Spectral count showed apparent advantages over peak integration because several peptides per protein are automatically averaged, the linear dynamic range of quantitation increases in complex matrices and the number of quantified proteins surpasses the number of proteins using peak integration. Thus, for the need of rapid comparative analysis of highly complex protein samples, spectral count enables sample pattern recognition and identification of biomarkers in nongel based proteomic studies.     

Anisotropic multiplicative elastoplasticity for the prediction of earings in sheet forming

In this work, the simulation of earings in cup drawing by means of a recently developed anisotropic combined hardening material model is discussed. The model represents a multiplicative formulation of anisotropic elastoplasticity in the finite strain regime with nonlinear kinematic and isotropic hardening. Plastic anisotropy is described by the use of second-order structure tensors as additional arguments in the representation of the yield function and the plastic flow rule. The evolution equations are integrated by a form of the exponential map that preserves the plastic volume and the symmetry of the internal variables. Finite element simulations of cylindrical cup drawing processes are performed by means of ABAQUS/Standard where the discussed material model has been implemented into a user-defined reduced integration solid-shell element. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)