Sample Preparation

High-temperature creep tests were conducted on polycrystalline copper of commercial purity in order to investigate the inter-relationship between the extent and the rate of grain boundary sliding (GBS) and the development of internal cavitation. An image processing technique was used to provide quantitative information on the size and shape of the cavities formed over a range of stresses and at temperatures from 673 to 873 K. The results demonstrate that cavity development is inhomogeneous within any specimen, such that there is an increase in the level of cavitation in regions of higher local strain. It is shown by quantitative measurements that the total cavitated area increases at the faster sliding rates, but the number density of cavities decreases at the highest sliding rates because of cavity interlinkage. When interlinkage is taken into account, the results confirm that the overall level of cavitation is related to the occurrence of GBS.

The functional properties of fats are determined by the distribution pattern of fatty acid residues in their acylglycerols, which may be modified by ester interchange (transesterification). In the margarine industry, the time course of the transesterification of fat blends is monitored by assaying for the amount of the solid fraction at different temperatures (SFC-solid fat content) currently measured by nuclear magnetic resonance (NMR). The aim of this study was to evaluate the feasibility of near infrared spectroscopy (NIRS) to quantify ...

Fabrication of microfluidic systems capable of extracting and isolating nucleic acids from biological samples and preparing them for downstream applications within the same device is of interest as on-chip sample preparation reduces the time and effort expended on multi-step benchtop procedures. A microfluidic chip capable of cell lysis, nucleic acid extraction and immobilization has been developed in our laboratory. This report focuses on substrate development and chip integration of the nucleic acid immobilization platform. The immobilization region was initially developed using poly-adenylated mRNA released from normal human lymphoblastoid cells. After immobilization, the mRNA remains functional for amplification by the reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qPCR) gene expression analyses. Detailed surface functionalization, chemical modification, and covalent oligonucleotide immobilization methods are described. Vapor and liquid ...

... Available online 12 March 2002. Abstract. The present contribution shows the results of tests on geological materials for determination of the rare-earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, as well as Y and Sc. ...

The exoskeleton of the lobster Homarus americanus is a multiphase biological composite material which consists of an organic matrix (crystalline α-chitin fibers and various types of non-crystalline proteins) and minerals (mainly calcite). In this study we discuss experimental data about the mesoscopic structure and the crystallographic texture (orientation distribution) of the α-chitin–protein fiber network in this material. The synchrotron measurements reveal very strong crystallographic textures of the α-chitin. According to these data, a large fraction of the α-chitin lattice cells is arranged with their longest axis parallel to the normal of the surface of the exoskeleton. Additionally, a smaller fraction of the α-chitin cells is oriented with their longest axis perpendicular to the cuticle surface. These structural investigations reveal the pronounced role of crystallographic orientation distributions in mineralized biological composite materials which may be of relevance for an improved understanding of biological and bio-inspired nano-composites.

Indium tungsten oxide (In6WO12) powders and thin films were prepared from a 2,4-pentanedione solution containing In(NO3)·xH2O and WCl6. X-ray diffraction results indicated that phase-pure In6WO12 powder formed after drying and heating the solution at 900 °C. Glancing X-ray diffraction results indicated that thin-film samples prepared on fused quartz substrates at 600 and 700 °C contained a disordered fluorite-related phase whereas those prepared at 800 °C contained the ordered compound—In6WO12. Films prepared at 900 °C reacted with the substrate to form In2Si2O7. Despite the chemical and structural similarity of In6WO12 to several indium-containing fluorite-related oxides, including In2O3, In3Sn4O12, and Ga3−xIn5+xSn2O16, the resistivity of the films prepared in this study ranged from 70 to 720 Ω cm, which is several orders of magnitude higher than reported for the related oxides (approx. 10−3 Ω cm). The band gaps of the films prepared at 600 and 700 °C were estimated from optical transmittance measurements to be 4.1 and 3.8 eV, respectively. Films prepared at 700 °C exhibited substantial coloration when exposed to n-butyl lithium whereas those prepared at 800 °C did not.

A method was validated for the multi-residue analysis of 82 pesticides in grapes at ≤25 ng/g level. Berry samples (10 g) mixed with sodium sulphate (10 g) were extracted with ethyl acetate (10 mL); cleaned by dispersive solid phase extraction and the results were obtained by liquid chromatography–tandem mass spectrometry. Reduction in sample size and proportion of ethyl acetate for extraction did not affect accuracy or precision of analysis when compared to the reported methods and was also statistically similar to the QuEChERS technique. The method was rugged (HorRat < 0.5) with <20% measurement uncertainties. Limit of quantification was <10 ng/g with recoveries 70–120% for most pesticides. The method offers cheaper and safer alternative to typical multi-residue analysis methods for grape.

In this paper, we discuss the synthesis of carbon-sulfur composite (a-C:S) films by vapour phase pyrolysis of maleic anhydride and sulfur. Structural changes in the system are analysed by scanning electron microscopy and powder X-ray diffraction. Microhardness test depicts an increase in the value of hardness with an increase in sulfur concentration. Electrical conductivity of composite samples varies with sulfur concentration. Magnetoresistance (MR) measurements show a drastic increase in the value of MR for the samples prepared at < 900°C. Thermal stability of these samples is analysed by thermogravimetric analysis, which depends on the host structure and the amount of intercalated species.

A highly sensitive and reliable method for the enantioselective analysis of ibuprofen, ketoprofen and naproxen in wastewater and environmental water samples has been developed. These three pharmaceuticals are chiral molecules and the variable presence of their individual (R)- and (S)-enantiomers is of increasing interest for environmental analysis. An indirect method for enantioseparation was achieved by the derivatization of the (R)-