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Analytical Device (analytical + device)

Distribution by Scientific Domains

Chemistry	40%
Business, Economics, Finance and Accounting	40%

Selected Abstracts

Single cell manipulation, analytics, and label-free protein detection in microfluidic devices for systems nanobiology

ELECTROPHORESIS, Issue 19 2005
Wibke Hellmich
Abstract Single cell analytics for proteomic analysis is considered a key method in the framework of systems nanobiology which allows a novel proteomics without being subjected to ensemble-averaging, cell-cycle, or cell-population effects. We are currently developing a single cell analytical method for protein fingerprinting combining a structured microfluidic device with latest optical laser technology for single cell manipulation (trapping and steering), free-solution electrophoretical protein separation, and (label-free) protein detection. In this paper we report on first results of this novel analytical device focusing on three main issues. First, single biological cells were trapped, injected, steered, and deposited by means of optical tweezers in a poly(dimethylsiloxane) microfluidic device and consecutively lysed with SDS at a predefined position. Second, separation and detection of fluorescent dyes, amino acids, and proteins were achieved with LIF detection in the visible (VIS) (488,nm) as well as in the deep UV (266,nm) spectral range for label-free, native protein detection. Minute concentrations of 100,fM injected fluorescein could be detected in the VIS and a first protein separation and label-free detection could be achieved in the UV spectral range. Third, first analytical experiments with single Sf9 insect cells (Spodoptera frugiperda) in a tailored microfluidic device exhibiting distinct electropherograms of a green fluorescent protein-construct proved the validity of the concept. Thus, the presented microfluidic concept allows novel and fascinating single cell experiments for systems nanobiology in the future. [source]

Knowing What You Don't Know?

JOURNAL OF MANAGEMENT STUDIES, Issue 4 2004
Contradictions in Knowledge Management Research, Discourses
ABSTRACT Even though knowledge management scholars generally advocate explicit management of knowledge, there is research that cautions against the unintended consequences of such efforts. Some researchers go as far as arguing that knowledge and management are contradictory concepts (Alvesson and Kärreman, 2001). This paper explores the apparent double-edged nature of knowledge management by developing a theory-based framework that highlights different fundamental assumptions about knowledge and its management. This framework, which is an adaptation of Burrell and Morgan's four paradigms of social and organizational inquiry, distinguishes among a neo-functionalist, a constructivist, a critical and a dialogic discourse. We use the contradiction of managing tacit knowledge, which has been highlighted in the knowledge management literature, as an analytical device to explore the four discourses in more detail. We show how notions of knowledge, and what it means to manage knowledge, vary across the four discourses. We conclude that all four discourses need to be appreciated, understood and represented in knowledge management research for this area of inquiry to deal with the rich and problematic nature of managing knowledge in practice. [source]

Time to Ditch the Natural Rate?

THE ECONOMIC RECORD, Issue 246 2003
A. J. Hagger
We urge macroeconomists to abandon the ,natural rate' as an analytical device on the ground that it has become a source of great and growing confusion. But we press them to recognise that it has great potential as a policy tool provided we grasp the central idea of a hypothetical unemployment rate, which can be compared with the actual unemployment rate. We integrate three hypothetical unemployment rates with the help of an exploratory macro model and then present a quarterly series for each for Australia for the period 1986(2) to 1997(2). We explain how such series could help in policy-making. [source]

Adjustment and control of SERS activity of metal substrates by pressure

JOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2010
Lixin Xia
Abstract Metal pellets of silver and copper for surface-enhanced Raman scattering (SERS) spectroscopy were prepared by compression with different pressures. It was found that the SERS activity of the pellet could be controlled by pressure. Enhanced Raman scattering properties of the metal pellets in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 or 514 nm could be obtained by choosing proper pressure of pellatization. The SERS peak intensity of the band at ,1584 cm,1 of 4-MBA adsorbed on the metal pellets varies as a function of applied pressure, and which is about 1.2,32 times greater than when it is adsorbed on silver and copper particles. The calculated results of three-dimensional finite-difference time-domain method (3D-FDTD) are in good agreement with the experimental data. Moreover, no spurious peaks appear in the SERS spectra of the samples because no other chemicals are involved in the simple preparation process of the metal pellets, which will facilitate its use as an SERS-active substrate for analytical purposes. In summary, SERS-active metal pellets can be produced simply and cost effectively by the method reported here, and this method is expected to be utilized in the development of SERS-based analytical devices. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Gold-coated fused-silica sheathless electrospray emitters based on vapor-deposited titanium adhesion layers

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2003
Stefan Nilsson
Gold-coated fused-silica electrospray (ES) emitters based on vapor-deposited adhesion layers of titanium have been manufactured to investigate the possibilities of producing durable ES emitters applicable in chip-based analytical devices. The stabilities of the emitters were studied by both electrospray and electrochemical experiments and a marked increase in the emitter lifetime, compared to that for Cr/Au coated emitters, was found for the Ti/Au emitters in the ES durability tests. This indicates that Ti (rather than Cr) adhesion layers should be used in association with large-scale fabrication of ES emitters by vapor-deposition techniques. The lifetime of about 500,700 hours also allowed the Ti/Au-coated emitter to be used as an integrated part of a capillary liquid chromatography column coupled to a mass spectrometer in a series of LC/MS experiments. The Ti/Au coating was further studied by electrochemical techniques and scanning electron microscopy in conjunction with X-ray spectroscopy. It is shown that the eventual failure of the Ti/Au emitters in ES experiments was due to an almost complete detachment of the gold layer. Experimental evidence suggests that the detachment of the gold coating was due to a reduced adhesion to the titanium layer during oxidation in positive electrospray. Most likely, this was caused by the formation of an oxide layer on the titanium film. It is thus shown that unlimited emitter stabilities are not automatically obtained even if the metallic adhesion layer is stabilized by an oxide formation under positive electrospray conditions. Copyright © 2003 John Wiley & Sons, Ltd. [source]