Chemical Composition and Mechanical Characteristic of Nitrogen Ion Beam Mixed Carbon Nanolayer

Ion beam methods for modification of nanohardness of surface nanolayers of the titanium alloy Ti6AI4V were applied. After deposition of carbon nanolayers by electron beam evaporation, the ion implantation of nitrogen into samples was carried out. The chemical composition of the modified surface area was investigated by AES （auger electron spectroscopy）. The nanohardness of resulted ion beam modified surface nanolayers were investigated by nanoindentation testing. The measured concentration profiles indicate the atomic mixing of carbon into the substrate. It was found that the modified samples had a markedly higher nanohardness than the unmodified samples. The increased nanohardness is attributed to the newly created phases in the surface area.     

Remotely detected NMR for the characterization of flow and fast chromatographic separations using organic polymer monoliths

An application of remotely detected magnetic resonance imaging is demonstrated for the characterization of flow and the detection of fast, small molecule separations within hypercrosslinked polymer monoliths. The hyper-cross-linked monoliths exhibited excellent ruggedness, with a transit time relative standard deviation of less than 2.1%, even after more than 300 column volumes were pumped through at high pressure and flow. Magnetic resonance imaging enabled high-resolution intensity and velocity-encoded images of mobile phase flow through the monolith. The images confirm that the presence of a polymer monolith within the capillary disrupts the parabolic laminar flow profile that is characteristic of mobile phase flow within an open tube. As a result, the mobile phase and analytes are equally distributed in the radial direction throughout the monolith. Also, in-line monitoring of chromatographic separations of small molecules at high flow rates is shown. The coupling of monolithic chromatography columns and NMR provides both real-time peak detection and chemical shift information for small aromatic molecules. These experiments demonstrate the unique power of magnetic resonance, both direct and remote, in studying chromatographic processes.     

A numerical investigation of direct and indirect closed-loop architectures for estimating nonminimum-phase zeros

ABSTRACT

This paper presents a numerical investigation of three direct architectures and three indirect architectures for identifying a plant operating in closed loop. Motivated by adaptive control of systems with nonminimum-phase (NMP) zeros and taking advantage of the fact that zeros are not moved by feedback, the performance metric is the accuracy of the estimates of the NMP zeros of the plant. Assuming known plant order, single-input, single-output, infinite-impulse-response models are constructed in the presence of process and sensor noise. Least squares provides the baseline estimation technique, and prediction error methods are used to account for correlation between the model input and noise. The goal is to compare the accuracy of the NMP-zero estimates obtained from each method and for each architecture.     

New CSPs based on peptidomimetics: efficient chiral selectors in enantioselective separations

Summary Two different families of peptidomimetics have been synthesized and used as chiral selectors for enantioselective chromatography. The functionalization of compounds with multiple nitrogen atoms allows their use in the preparation of chiral stationary phases (CSPs), with acrylic or styril comonomers, in both bead and monolithic formats. Some of these separation media, having the appropriate morphological properties for their use in chromatographic columns, were able to efficiently discriminate enantiomers of aminoacid derivatives and pharmaceuticals such as Oxazepam. Received: 24 September 2001/Revised version: 2 January 2002/ Accepted: 21 January 2002     

Multi-Scale Analysis of Vacuum Contact Drying

The modeling of the unit operation of vacuum contact drying is approached as a multi-scale problem. At the particle assembly length scale, effective transport properties (thermal conductivity, relative gas- and liquid-phase permeability) have been determined computationally by simulations on reconstructed porous media and verified by direct measurements. A distributed-parameter model of vacuum contact drying including liquid and vapor flow and differential energy balance has been formulated and used for the calculation of drying time as function of vacuum level, temperature, vessel diameter, and batch size at the unit operation length scale. Drying curves for a model system of sodium carbonate-isopropanol have been measured experimentally and compared with the model predictions. A very good agreement has been found.     

Expression,Receptor Binding,and Biophysical Characterization of Guinea Pig Insulin desB30: A Monomeric Insulin Variant

Here we report, for the first time, the heterologous expression of desB30 guinea pig insulin (GI desB30) in the yeast Saccharomyces cerevisiae. The affinities of GI desB30 for the insulin receptor A and the IGF‐I receptor were also quantified for the first time. Small‐angle X‐ray scattering and analytical ultracentrifugation studies confirmed that GI desB30 did not form dimers or hexamers, in contrast to human insulin. Sizeexclusion chromatography connected to inductively coupled plasma mass spectrometry revealed that GI desB30 has affinity towards several divalent metal ions. These studies did not indicate the formation of any larger structures of GI desB30 in the presence of various divalent metal ions, but did indicate that GI desB30 has an affinity towards Mn, Co, and Cu ions. Finally, the low affinity for the insulin receptor and the very low affinity for the IGF‐I receptor by GI desB30 were quantified.     

Implementation of best available techniques in the sanitation of relict burdens

The paper deals with the elimination of highly toxic and persistent relict burdens caused by polychlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls, hexachlorobenzene, γ-isomer of hexachlorocyclohexane and other organic halogen derivatives. The technology is used in eliminating the aforementioned contaminants from soil, rubble and metal parts of former machinery with the use of best available techniques. Such a technology has been implemented in the northern part of the town of Neratovice and the Spolana company, plc, which formerly used to be a significant producer of pesticides in the Czech Republic.