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Analytical Instruments (analytical + instruments)

Distribution by Scientific Domains
Polymers and Materials Science40%

Selected Abstracts

Photobleaching-based flow measurement in a commercial capillary electrophoresis chip instrument

ELECTROPHORESIS, Issue 6 2008
Guiren R. Wang Professor
Abstract For microfluidic analytical instruments, a facile, fast, and accurate instrument test is highly demanded. The test includes the quantitative verification of the relationship between pressure drop and flow velocity for the hydrodynamic pump, between the electric voltage and electroosmotic flow (EOF) for the high-voltage supply, and the chip quality. The key point for the test is the measurement of the flow velocity. However, most currently available velocimetries cannot be directly used without any instrumental modification or adding extra instruments. We applied a recently developed Laser Induced Fluorescence Photobleaching Anemometer (LIFPA) for the instrument test through measuring fluid flow velocity in a microfluidic instrument with optical measurement without any modification and extra instrument. We have successfully used the method to test Caliper HTS 250 System from Caliper Life Sciences (Hopkinton, MA) with its own light source and detector. The experimental result demonstrates that this single-point method of measuring flow velocity can be easily used for accurate test of a microfluidic instrument in less than 10,min at extremely low cost without any modification and extra instrument. [source]

Validation of Analytical Measurements by Single-trial and Collaborative Study

JOURNAL OF FOOD SCIENCE EDUCATION, Issue 1 2003
C.E. Carpenter
ABSTRACT: Validation of analytical measurements is necessary to report scientifically justifiable results. In this exercise, students validate the accuracy and precision of analytical instruments in single trials and in collaborative study, and validation results are used to report measurements in a scientifically justifiable manner. Tables are provided to guide data collection and to clarify reporting of results. A set of allied questions explores validation theory to develop student understanding, stimulate discussion, and provide feedback to the instructor regarding student comprehension. References are given that reinforce the validation concepts. [source]

Synthesis of Nanostructured Silicon Carbide through an Integrated Mechanical and Thermal Activation Process

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2002
Ruiming Ren
Changes of crystal structures and microstructures of SiO2 and graphite powder mixtures induced by high-energy milling, the effect of these changes on the reactivity of reactants, and the mechanism of enhanced SiC formation have been studied using a variety of analytical instruments, including X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, solid-state 29Si nuclear magnetic resonance, and nitrogen adsorption (i.e., the BET method). High-energy milling before carbothermic reduction leads to substantial changes in the structural and energy states of the reactants, which in turn increases the reactivity of the reactants and enhances the formation of nanostructured SiC particles. Furthermore, the structural and energy-state changes contribute to the enhanced SiC formation through the increased reaction kinetics as well as the increased reaction driving force. [source]

Cover Picture: Plasma Process.

PLASMA PROCESSES AND POLYMERS, Issue 3 2006
Polym.
Cover: Plasma polymerized films undergo ageing processes when they are exposed to ambient air. The surface of a really fresh film can be studied when the reactor is online with analytical instruments, such as X-ray photoelectron or absorption spectrometers as well as Time-of-Flight SIMS. Allyl amine plasma polymers deposited at varied plasma parameters were thoroughly investigated using this approach. Further details can be found in the Full Paper by U. Oran,* S. Swaraj, A. Lippitz, and W. E. S. Unger on page 288. [source]

Integrated strategies for assessment of metabolite exposure in humans during drug development: analytical challenges and clinical development considerations

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2009
Mingshe Zhu
Abstract Monitoring the exposure of a drug and its metabolites in humans and preclinical species during drug development is required to ensure that the safety of drug-related components in humans are adequately assessed in the standard toxicology studies. Recently published FDA guidance on metabolites in safety testing (MIST) has generated broad discussion from various perspectives. Most of the opinions and experiences shared among the scientific community are scientifically sound and practical. There are various approaches to assess the metabolite exposure margin between toxicology species and humans: either by direct or indirect comparison or by qualitative or quantitative comparison. The choice of when and how to pursuit metabolite assessment is based on the overall development strategy of the compound. Therefore, it is important to understand the utility and limitations of analytical instruments in order to apply an appropriate analytical tool to address specific questions posed at different stages of drug development. The urgency of metabolite monitoring depends on the intrinsic nature of the compound, therapeutic intent and objective of the clinical development. The strategy for assessing metabolite exposure in humans should be a holistic approach considering clinical situations and cumulative knowledge of the metabolism of the drug in order to appropriately address metabolite safety in humans. A one-size-fits-all approach is rarely the best use of resources. Copyright © 2009 John Wiley & Sons, Ltd. [source]