Supercritical fluid fractionation of fish oil esters using incremental pressure programming and a temperature gradient

Incremental pressure programming was demonstrated to be an effective technique for increasing the yield of 90% pure allcis-5,8,11,14,17-ethyl eicosapentaenoate (EPA) in the fractionation of urea-crystallized fish oil ethyl esters using supercritical fluid CO₂. The fractionations, which also produced high purity allcis-4,7,10,13,16,19-ethyl docosahexaenoate (DHA), were performed using a column temperature gradient. In initial experiments, the maximum temperature of the superimposed gradient was 80°C, and processing pressures ranged from 1900–2200 psi. By reduction of processing pressures, comparable yields of EPA were obtained from fractionations in which the maximum temperatures in the gradient were 70°C and 60°C.     

Crystal Structures of Two Orthorhombic Zirconias

The crystal structures of orthorhombic zirconias formed by cooling magnesia-partially-stabilized zirconia (Mg-PSZ) (space group Pbc 2₁) and by quenching zirconia powder from 600°C and 6 GPa (space group Pbca ) are compared and contrasted. It is demonstrated that the two structures are easily distinguished by the neutron powder diffraction techniques used to establish them. The occurrence of two distinct phases is hence proved. Structural relationships between these two phases and also with the in situ high-pressure structure proposed from X-ray diffraction (XRD) are discussed. The three structures are virtually indistinguishable by XRD and so the structure of the high-pressure form "in situ" is considered to remain unknown.     

Antibacterial LDPE Nanocomposites Based on Zinc Oxide Nanoparticles/Vermiculite Nanofiller

Polyethylene (PE) nanocomposites with the zinc oxide-nanoparticles/vermiculite nanofiller were prepared in two-steps. In first step, the ZnO-np/V nanofiller were prepared by the mechanochemical method followed by a heat treatment at 650?°C for 90 min. In second step, this nanofiller was used in concentration 3, 6, 10 and 15 wt% for PE nanocomposites preparation via melt compounding technique, the nanocomposites plates were pressed. The particles morphology of the ZnO-np/V nanofiller, arrangement of the ZnO-np/V nanofiller and surface of the PE plates were studied using scanning electron microscopy, optical light microscopy and atomic force microscopy. The surface roughness of the PE plates was evaluated from AFM measurements. Structural changes of the ZnO-np/V nanofiller in PE nanocomposites were monitored using X-ray diffraction analysis and Fourier transform infrared analysis. The gradual and long-term antibacterial effect of PE nanocomposites was tested on the Gram positive bacteria E. faecalis by counting the colony forming units number.     

Steady Groundwater Transport of Highway Deicing Agent Constituents from an Infiltration Basin

The highway deicing agent groundwater plume from an infiltration basin in the Plymouth-Carver Aquifer near State Route 25 in southeastern Massachusetts is modeled and measured in order to assess the impact of the basin on groundwater transport processes. The advective transport model superimposes the existing steady models of axisymmetric basin hydraulics of Zlotnik and Ledder in 1992 and the two-dimensional ambient flow of Gelhar and Wilson in 1974. The basin component incorporates a surface source of finite-radius into a Hankel transform model for unconfined aquifers, whereas the ambient component varies linearly in the horizontal and vertical directions. Contaminant streamlines describe the resulting groundwater plume, and highway deicing agent constituents provide useful tracers. A simple vertical dispersion model quantifies the spread of contaminants across the bottom of the plume. Deicing agent constituent data calibrate a 17?m basin radius, a 45?m plume width, a bottom streamline 6–10?m below the water table, and a vertical dispersivity of 34?cm. The latter value is comparable to the amplitude of vertical excursions caused by storm scale fluctuations of hydraulic head, as measured by Ostendorf et al. in 2007. Infiltration basins alter ambient advection by displacing streamlines downward and augment vertical mixing by imposing aperiodic vertical fluctuations on the ambient flow field.     

Corrosion resistance studies on grain-boundary etched drug-eluting stents

In this paper we compare the influence of different microstructures on the corrosion resistance of new drug-eluting stainless steel stents, which have been produced by grain-boundary-selective electrochemical etching processes. The morphology of the stent surfaces was analysed by scanning electron microscopy (SEM), and the surface composition was investigated with Auger electron spectroscopy (AES) as well as with energy dispersive X-ray analysis (EDX). The passivity of the different microstructured stents was studied by cyclovoltammetry in Ringer solution. Release of nickel and chromium was assessed after potentiostatic experiments in Ringer solution by analysing the collected electrolyte with AAS. For stents produced by different two-step etching procedures bringing about ideal morphologies regarding the mechanical and biological properties of the surface, no significant differences in the passivation behaviour could be observed. A two-step process using first nitric acid and oxalic acid in a second step produces stent surfaces with very good corrosion properties: electrochemical analysis shows that the range of stable passivity is the same as for conventional stent surfaces, and low rates of nickel and chromium release are observed. The etching procedures do not seem to change the surface oxide layer composition.     

Synthesis and characterization of the first fluorescent nonpeptide NPY Y1 receptor antagonist

Cyanine-5-labelled neuropeptide Y (NPY) was demonstrated to be an ideal universal fluorescent ligand for the combined investigation of NPY Y(1), Y(2) and Y(5) receptors. With respect to improved stability, detection of receptor subtypes in cells and tissues, and prevention of receptor internalization, small nonpeptidic fluorescent antagonists should be superior. Here we present a set of four fluorescent nonpeptide NPY Y(1) receptor (Y(1)R) antagonists. The highest affinity was obtained by labelling an N(G)-(6-aminohexanoyl)argininamide derived from the Y(1)R antagonist BIBP 3226, with Py-1, a small pyrylium dye. The fluorescent pyridinium-type Y(1)R antagonist, compound 4 had K(i) values of 29 nM and 2.7 nM, which were determined by radioligand binding and flow cytometry under equilibrium conditions, respectively; 4 had a K(b) value of 0.6 nM (Ca(2+) assay). The large Stoke's shift (541 vs. 615 nm) in buffer (PBS, pH 7.4) in the presence of 1% BSA and the red emission (quantum yield 56%) are advantageous with respect to the signal-to-noise ratio. The new probe was successfully used in fluorescence-based binding experiments evaluated by flow cytometry and confocal microscopy; this demonstrates the potential of pyrylium dyes for the preparation of fluorescent ligands that are applicable for the study of G protein-coupled receptors on living cells.     

Reliability considerations of III-nitride microelectronic devices

The success of III-nitride optoelectronic devices paths the way towards emerging devices in microelectronics. These devices are currently at the threshold to commercialization, therefore reliability considerations are becoming increasingly important. This paper reviews the material and process technology of III-nitride microelectronic devices in the scope of reliability. Since statistical reliability data are lacking in the current state of research the review starts with a summary of how reliability can be designed into process modules being relevant for microelectronic devices. This includes a discussion of the most important issues of material growth, metallization, implantation, dry etching and surface passivation. The subsequent chapter focuses to microelectronic devices and highlights technological challenges that have to be met in order to obtain reliable devices. Finally, results of lifetime experiments (thermal aging) demonstrate that III-nitride devices have the potential for reliable operation even at elevated temperatures up to 400°C.     

In-line measurement of tempered cocoa butter and chocolate by means of near-infrared spectroscopy

In the present work cocoa butter and chocolate were precrystallized by means of a newly developed shear crystallizer. The shear crystallizer was integrated into a circular loop. The handling of precrystallized cocoa butter showed a high dependency on the timing of applied analysis. Differential scanning calorimetry, calorimetry, rheometry, and in-line near-infrared (NIR) were all directly influenced by the fat crystal structure. Nevertheless, for cocoa butter it was shown that mechanical energy input (rpm) had a significant influence on viscosity, melting enthalpy, and slope at the second point of inflection of a temper curve. Experiments with cocoa butter at constant exit temperature showed a linear increase of viscosity between 0.1 and 0.8 Pa·s in the range of 300 to 1300 rpm. Melting enthalpy increased in the same rpm interval from 0.02 to 2.5 J/g. Solidification time (from 4.5 to 0.5 min) and slope (from 0.82 to 0.15, second point of inflection of temper curve) consequently decreased (both with exponential approximation). For cocoa butter, slope and solidification time correlated linearly whereas solidification time and viscosity followed a power law fit. This proved that defined relationships exist between rheological data and data from temper curve measurements. Viscosity was linearly dependent on crystal content. By means of NIR spectroscopy good correlation models for cocoa butter viscosity, enthalpy (crystal content), and slope values were found. For precrystallized chocolate, analytical values such as viscosity and slope values were detected off-line and used for calibration of NIR spectroscopy.     

Zur praktischen Ermittlung von statischen Windlasten an Bauwerken mit der Singularitätenmethode

The practical calculation of static wind loads on buildings. We will see here, how static wind loads on buildings may be approximated using results of former research [1]. It is possible to apply the calculation of standard profiles combined with a sufficient connection of their estimated values. The aim of the acute research shall present a comprehensive physical system of fluid mechanics with dead water zones (wakes).