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Measurement of Low Concentration of Nanosized Objects Suspended in a Liquid Medium

Abstract

The new optical scheme of refractometer with temperature stabilisation 10−2 °C is developed, which allows measuring a refractive index of the sample with accuracy not worse than 10−5; dependence of refraction index on concentration of SiO2 nanoparticles in liquid suspension is obtained within the framework of the research.

Open access
An Interval Estimator for Chlorine Monitoring in Drinking Water Distribution Systems Under Uncertain System Dynamics, Inputs and Chlorine Concentration Measurement Errors

Abstract

The design of an interval observer for estimation of unmeasured state variables with application to drinking water distribution systems is described. In particular, the design process of such an observer is considered for estimation of the water quality described by the concentration of free chlorine. The interval observer is derived to produce the robust interval bounds on the estimated water quality state variables. The stability and robustness of the interval observer are investigated under uncertainty in system dynamics, inputs, initial conditions and measurement errors. The bounds on the estimated variables are generated by solving two systems of first-order ordinary differential equations. For that reason, despite a large scale of the systems, the numerical efficiency is sufficient for the on-line monitoring of the water quality. Finally, in order to validate the performance of the observer, it is applied to the model of a real water distribution network.

Open access
Devices and Methods for Practical Use to Measure Relative Air Humidity / Apparate und Methoden zur Messung der relativen Luftfeuchte für den praktischen Gebrauch

ABSTRACT

Summary Overview

1. Weighing method

2. Dew point method

3. Evaporation method

4. Psychrometric method

5. Hygroscopic method

6. Diffusion hygrometer

7. Colour change of surface

8. Procedure with conductivity measurement

9. Gas concentration measurement

10. Thermoflux gas concentration measurement

Open access
Statistical Method Based on Confidence and Prediction Regions for Analysis of Volatile Organic Compounds in Human Breath Gas

Statistical Method Based on Confidence and Prediction Regions for Analysis of Volatile Organic Compounds in Human Breath Gas

In this paper we introduce two confidence and two prediction regions for statistical characterization of concentration measurements of product ions in order to discriminate various groups of persons for prospective better detection of primary lung cancer. Two MATLAB algorithms have been created for more adequate description of concentration measurements of volatile organic compounds in human breath gas for potential detection of primary lung cancer and for evaluation of the appropriate confidence and prediction regions.

Open access
Iodine Molecules Differential Absorption Cross section Lidar Studies

Iodine Molecules Differential Absorption Cross section Lidar Studies

Lidar monitoring of the gaseous molecules in atmosphere can be used for concentration measurements of the toxic pollutants in air of the urban and industrial regions. Such a concentration study in the multi-components gaseous mixture by lidar technique is a complex problem in atmospheric pollution monitoring. The differential absorption lidar (DA-lidar) is the most preferable for the detection of iodine molecules at very low concentration levels. The iodine molecules absorption cross section in the laboratory lidar studies and lidar equation simulation in this lidar variant corresponds with earlier data.

Open access
Analysis of simultaneous time series of indoor, outdoor and soil air radon concentrations, meteorological and seismic data

Abstract

It is well known that the temporal dynamic of indoor and outdoor radon concentrations show complex patterns, which are partly not easy to interpret. Clearly, for physical reasons, they must be related to possibly variable conditions of radon generation, migration and atmospheric dispersion and accumulation. The aim of this study was to analyse long-time series of simultaneously measured indoor and outdoor radon concentrations, together with environmental quantities, which may act as control variables of Rn. The study was performed in Chiba, Japan, using two ionization chambers for parallel indoor and outdoor radon concentrations measurements over 4 years. Meteorological and seismic data were obtained from the Japan Metrological Agency (JMA).

Open access
One-Dimensional Gas Concentration Profiles Within a Burning Cigarette During a Puff

Abstract

A technique for axial concentration measurements of several gas phase components of cigarette smoke during a two-second puff has been described. Gas concentration profiles constructed from these measurements were used to determine the axial order of the reactions which determine these concentrations. A one-dimensional model combustion reaction profile and a one-dimensional model coal temperature profile were presented. The diffusivities of several combustion gases through cigarette paper were calculated from the concentration data using the Owens-Reynolds model for the isothermal diffusion of gases through cigarette paper.

Open access
The Measurement of Intrapuff Nicotine Yield

Abstract

Time-resolved measurements of intrapuff nicotine yield in mainstream smoke have been performed with a specially designed intrapuff smoking apparatus (IPSA). The IPSA-filter traversing mechanism collects mainstream particles on a rectangular filter pad which moves at a constant velocity perpendicular to the direction of smoke flow at the mouthend of the cigarette. Filter pads were assayed by two analytical techniques. Standard gas chromatographic (GC) methodology was used to quantify nicotine mass in five equal time segments per puff. A second method, using a Berthold TLC-Linear Analyser, measured total radioactivity across the pad for samples from [2'-14C]-nicotine labelled cigarettes. Intrapuff nicotine concentrations were determined from measured puff flow-rate profiles and the collected masses of nicotine on the filters. GC nicotine concentration measurements correlated well with total activity from the scanner measurements. Studies carried out with filtered full-flavour cigarettes revealed that nicotine concentrations in the smoke vary significantly during a puff. This work provides a new technique for studying time-resolved yields of mainstream smoke components. It may potentially be used to elucidate mechanisms controlling the yield of nicotine and other mainstream smoke components.

Open access
Influence of Non-Oxidised and Oxidised Rapeseed Oil Consumption on Liver Metabolism Pathways and Non-Alcoholic Steatohepatitis Development in Rabbits

Abstract

For 24 weeks, rabbits were fed feed containing non-oxidised or oxidised rapeseed oil. At the beginning of the experiment and every six weeks the rabbits were weighed and blood was taken. After the experiment was completed, their liver was dissected for biochemical and histological examinations. The activity of alanine aminotransferase, aspartate aminotrasferase, glutamate dehydrogenase, sorbitol dehydrogenase, and aldolase in blood plasma and liver were determined. Enzymes of the protein and liver metabolic pathways were determined using kinetic and spectrophotometric methods. The content of fatty acids was determined by means of fatty acid methyl ester concentration measurement using gas chromatography. It was found that the applied diet with oxidised rapeseed oil caused the development of slight liver steatosis and disturbances in the activity of enzymes involved in the liver pathways, despite the fact that it was a balanced diet, and differed only in the ratio of saturated to unsaturated fatty acids. The obtained results indicate that more profound oil oxidation and its increased supply in diet may result in the development of liver steatosis.

Open access
Kinetic Modelling of Drug Release from Pentoxifylline Matrix Tablets based on Hydrophilic, Lipophilic and Inert Polymers

Abstract

Pentoxifylline is a xanthine derivative used in the treatment of peripheral vascular disease, which because of its pharmacokinetic and pharmacologic profile is an ideal candidate for the development of extended release formulations. The aim of this study is to present a kinetic analysis of the pentoxifylline release from different extended release tablets formulations, using mechanistic and empirical kinetic models. A number of 28 formulations were prepared and analysed; the analysed formulations differed in the nature of the matrix forming polymers (hydrophilic, lipophilic, inert) and in their concentrations. Measurements were conducted in comparison with the reference product Trental 400 mg (Aventis Pharma). The conditions for the dissolution study were according to official regulations of USP 36: apparatus no. 2, dissolution medium water, volume of dissolution medium is 1,000 mL, rotation speed is 50 rpm, spectrophotometric assay at 274 nm. Six mathematical models, five mechanistic (0 orders, 1st-order release, Higuchi, Hopfenberg, Hixson-Crowell) and one empirical (Peppas), were fitted to pentoxifylline dissolution profile from each pharmaceutical formulation. The representative model describing the kinetics of pentoxifylline release was the 1st-order release, and its characteristic parameters were calculated and analysed.

Open access