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Model Samples (model + sample)

Distribution by Scientific Domains
Chemistry28%

Selected Abstracts

Isolation of DNA from genetically modified oils by fast protein liquid chromatography

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2010
Li Huang
Summary In this study, a novel method of fast protein liquid chromatography (FPLC) anion exchange chromatography was developed for isolation of DNA from processed genetically modified (GM) oils. Four kinds of different GM edible oil had been chosen as model sample. Salmon DNA was used as the control sample to determine the pH values and NaCl in mobile phase buffer. Applying pH 8 and NaCl gradient 0.5,2 m were chosen for the DNA isolation. The quality and purity of isolated DNA were tested with agarose gel electrophoresis, scanned with UV absorbance spectra and amplified by polymerase chain reaction (PCR). The result indicated that the quantity of DNA isolated by FPLC was suitable for further PCR analyses. Furthermore, it is more effective and less time-consuming in comparison with cetyltrimethylammonium bromide method and High Pure GMO Sample Preparation Kit method. [source]

Investigation of HOLZ rings in EBSD patterns

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2007
E. Langer
Abstract Higher-Order Laue Zone (HOLZ) rings and their appearance in Electron Backscattered Diffraction (EBSD) pattern from molybdenum were fundamentally investigated in the Scanning Electron Microscope. HOLZ rings of the type ,100,, ,110,, ,111,, ,113, and ,133, could be unambiguous detected in EBSD pattern of different pure Mo crystals. The [100] HOLZ ring was observed more in detail in dependence on the accelerating energy in the pattern center, and the lattice spacing was determined for all energies. A relatively good accuracy could be obtained for Mo as model sample for problematical high atomic number materials. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Spatial Imaging of Cu2+ -Ion Release by Combining Alternating Current and Underpotential Stripping Mode Scanning Electrochemical Microscopy

ELECTROANALYSIS, Issue 2-3 2007
Dirk Ruhlig
Abstract Anodic underpotential stripping voltammetry was integrated into SECM in order to characterize local corrosion of metallic copper deposits on metal surfaces as a model for copper containing alloys. Primarily, the alternating current mode of SECM was applied in an electrolyte of low ionic strength for localizing possible corrosion sites without any perturbation of the corroding surface, e.g., by the presence of any redox mediator. Sequentially, the release of Cu2+ -ions was confirmed and locally visualized at the previously detected electrochemically active sites by means of spatially resolved anodic underpotential stripping voltammetry performed during SECM scanning. Underpotential stripping voltammetry of Cu2+ -ions was performed at a specifically developed 15,,m gold-coated Pt microelectrode used as SECM tip with a detection limit of 0.15,nM Cu2+ (N=4, RSD=6%) for an accumulation of 45,s at ,0.4,V. SECM images of model samples such as copper coated microelectrodes and lacquered metallic copper workpieces demonstrated the feasibility and applicability of combining AC- and underpotential stripping mode of SECM for local visualization of Cu2+ -ion release from corroding surfaces. [source]

Physical Modeling and Electrodynamic Characterization of Dielectric Slurries by Impedance Spectroscopy (Part II)

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008
Vladimir Petrovsky
Electrical characterization of dielectric slurries, as 0,3 composite systems, can provide valuable information on the dielectric properties of suspended particles. A new approach developed in our laboratory is based on impedance spectroscopy measurements of the slurries containing dispersed dielectric powders. Dielectric constants of the particles are determined through analysis of the low-frequency section of the impedance spectra. It was shown previously that this approach allows accurate and reliable measurement of dielectric constant of particles (,: ,100,2000) using host liquids (,: ,10,65). This study addresses the validation of this new method with physical model experiments using millimeter-sized sintered BaTiO3 model samples suspended in the liquid. Impedance spectra of barium titanate powder slurries were compared with the spectra of the model samples containing macroscopic cubes prepared by sintering of the same starting powder. This comparison shows a good agreement between the impedance spectra of powder and bulk BaTiO3 and validates the reliability of the new method to determine the dielectric constant of particulate materials. [source]

Synchrotron microscopy and spectroscopy for analysis of crystal defects in silicon

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2009
Winfried Seifert
Abstract The paper discusses the synchrotron-based microprobe techniques XBIC (X-ray beam induced current), ,-XRF (X-ray fluorescence microscopy) and ,-XAS (X-ray absorption microspectroscopy) and their application for studying electrical activity of defects and precipitation of transition metals in Si materials. Investigations were performed on samples of block-cast multicrystalline Si and on model samples cut from a bonded monocrystalline wafer. To analyze the precipitation sites, Ni, Cu and Fe were introduced intentionally into the samples. The detected precipitates were found to consist of silicides. Evidence for metal precipitates was also found in virtually uncontaminated as-grown block-cast Si. Besides Ni precipitates detected at a recombination active grain boundary, particles containing one or several metals (Cu, Fe, Ti, V) were observed. Unexpectedly, these particles seem to exhibit low only recombination activity. Further studies are necessary to identify their nature. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Neural Network Prediction of Biomass Digestibility Based on Structural Features

BIOTECHNOLOGY PROGRESS, Issue 2 2008
Jonathan P. O'Dwyer
Plots of biomass digestibility are linear with the natural logarithm of enzyme loading; the slope and intercept characterize biomass reactivity. The feed-forward back-propagation neural networks were performed to predict biomass digestibility by simulating the 1-, 6-, and 72-h slopes and intercepts of glucan, xylan, and total sugar hydrolyses of 147 poplar wood model samples with a variety of lignin contents, acetyl contents, and crystallinity indices. Regression analysis of the neural network models indicates that they performed satisfactorily. Increasing the dimensionality of the neural network input matrix allowed investigation of the influence glucan and xylan enzymatic hydrolyses have on each other. Glucan hydrolysis affected the last stage of xylan digestion, and xylan hydrolysis had no influence on glucan digestibility. This study has demonstrated that neural networks have good potential for predicting biomass digestibility over a wide range of enzyme loadings, thus providing the potential to design cost-effective pretreatment and saccharification processes. [source]