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A reliable and inexpensive device for measuring gas with low flow rates is described. The device works based on the principle of liquid displacement and is able to measure flows from 1 to 950 ml(.)h(-1). It also has improved counting logic and data processing capacity to avoid miscounting and provide a friendly interface for data display. (C) 2003 Elsevier B.V. All rights reserved.
The design and some properties of a new general-purpose isothermal microcalorimeter are reported. The instrument is a twin thermopile heat conduction calorimeter, which is designed for use up to 200 degreesC. The calorimetric units and surrounding heat sink are suspended inside a hollow aluminium construction, which is thermostated. Above that unit a second thermostated block is positioned and the
Catalysts belonging to the Mo-V-Nb-Te-O system have been prepared with both a slurry method and hydrothermal synthesis and were tested for propane and propylene ammoxidation to acrylonitrile. All samples were characterized with BET, XRD, ICP and XPS. The catalysts were found to consist of three phases, to which activity and selectivity correlations were made. The results indicate that both an orth
A new criterion is applied for characterization of the kinetic design of enzymes that should be favoured by a selective pressure in the direction of increased metabolic reaction flux. According to this criterion, the selectively favoured state of a metabolic sequence of enzyme reactions conforming to Michaelis-Menten kinetics is identical with the uniform one which is known to optimize reaction fl
Much of earlier work on predictive models for accidents has been focused on rural traffic or urban intersections. This work has aimed at identifying and investigating possible improvements to predictive models for accidents on urban links. A special focus has been on the accidents of vulnerable road users. The possible improvements investigated have been: a) the use of exposure data for vulnerabl
It is shown that the numbers of high level crossings by p dependent stationary Gaussian processes have asymptotically independent Poisson distributions if the observation interval and the height of the level increase in a coordinated way. The processes may be highly correlated, even linearly dependent.
The paper is devoted to an extension of one particular fact withintheory of partial stability, the so-called Pozharitsky Theorem,to the case of partial stabilization of nonlinear controlled system.It is shown that under appropriate assumptions partialstabilization of the system based on usage some Lyapunov functionconstructed from first integrals of the unforced system, impliesthat the Lyapunov fu
A simple assay was developed to estimate functional mannose-binding lectin (MBL) levels in serum based on the principle of yeast-induced bystander lysis of chicken erythrocytes (ChE). The assay is sensitive to inhibition by ethylene glycol bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) (which allows alternative pathway activation), ethylene diamine tetraacetic acid (EDTA), mannose,
In spite of the continuous development of production systems work-related musculoskeletal disorders is still a large problem. One reason might be the difficulties in quantifying the ergonomic effects of interventions. In this paper ergonomic consequences of technical and organisational changes were quantified in a plant for producing slats for parquet flooring. Muscle activity, work postures and m
Social phobia is one of the most frequent mental disorders and is accessible to two forms of scientifically validated treatments: anti-depressant drugs and cognitive behavior therapies (CBT). In this last case, graded exposure to feared social situations is one of the fundamental therapeutic ingredients. Virtual reality technologies are an interesting alternative to the standard exposure in social
The effect of pixel size on shape determination in screening digital mammography systems was studied using a shape identification task as the measured outcome. Ten microcalcifications on screen-films were digitised to a range of pixel sizes (2.5-200 μm) and extracted from computed radiography (CR) images (50 μm) acquired under equivalent imaging conditions. Fifteen observers attempted to identify
Polychlorinated biphenyls (PCBs) in water were extracted with a rebuilt extraction unit using 47 mm C18 solid-phase extraction (SPE) disks. Three types of disks (SPEC, ENVI and Empore) were investigated for the extraction of seven PCBs from 1 l reagent water spiked at two concentration levels (20 and 1000 ng/l). The Empore disks produced the best analyte recoveries (91–107% with R.S.D. of 1–8%) at
