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Biomedical subjects

F Winquist

Publications and source records attributed to F Winquist.

7 recordsLinked to original sources
PubMed2003

Use of an electronic tongue to analyze mold growth in liquid media.

The feasibility of employing an electronic tongue to measure the growth of mold in a liquid medium was studied. We used the electronic tongue developed at Linköping University, which is based on pulsed voltammetry and consists of an array of different metal electrodes. Instead of focusing on a single parameter, this device provides information about the condition or quality of a sample or process. Accordingly, the data obtained are complex, and multivariate methods such as principal component analysis (PCA) or projection to latent structures (PLS) are required to extract relevant information. A gas chromatographic technique was developed to measure ergosterol content in mold biomass and was subsequently used as a reference method to investigate the ability of the electronic tongue to measure the growth of mold in liquid media. The result shows that the electronic tongue can monitor mold growth in liquids. In PLS analysis, the electronic tongue signals correlate well with the amount of ergosterol in the mold biomass as well as the microbially induced changes in the pH of the medium.

Biomass↗
PubMed1999

Analysis of breath alcohol with a multisensor array: instrumental setup, characterization and evaluation.

The purpose of this work was to evaluate if it was possible to measure the alcohol concentration in breath by a multisensor array, i.e. an electronic nose. The most important aspects were to clarify technical advantages and disadvantages and if the technique is at all suitable for forensic breath alcohol analysis. Even though the system set-up was far from optimal it is clear that it was possible to quantify breath alcohol with a best-case root mean square error = 16.8 mol ppm ethanol (= 0.037 mg/l). However, the method needs significant development especially of the sensor devices. The sensor array was composed of ten metal oxide silicon field effect transistors (MOSFET) with various catalytic gates and one infrared-based CO2 sensor. The system was evaluated by monitoring the breath ethanol concentration of five test persons after intake of alcohol. Gas chromatography was used in parallel to measure the actual breath alcohol concentration. Different data evaluation techniques applied were projection to latent structure (PLS) and artificial neural networks (ANN).

Breath Tests↗
PubMed1997

Electronic nose for microbial quality classification of grains.

The odour of grains is in many countries the primary criterion of fitness for consumption. However, smelling of grain for quality grading should be avoided since inhalation of mould spores or toxins may be hazardous to the health and determinations of the off-odours are subjective. An electronic nose, i.e. a gas sensor array combined with a pattern recognition routine might serve as an alternative. We have used an electronic nose consisting of a sensor array with different types of sensors. The signal pattern from the sensors is collected by a computer and further processed by an artificial neural network (ANN) providing the pattern recognition system. Samples of oats, rye and barley with different odours and wheat with different levels of ergosterol, fungal and bacterial colony forming units (cfu) were heated in a chamber and the gas in the chamber was led over the sensory array. The ANN could predict the odour classes of good, mouldy, weakly and strongly musty oats with a high degree of accuracy. The ANN also indicated the percentage of mouldy barley or rye grains in mixtures with fresh grains. In wheat a high degree of correlation between ANN predictions and measured ergosterol as well as with fungal and bacterial cfu was observed. The electronic nose can be developed to provide a simple and fast method for quality classification of grain and is likely to find applications also in other areas of food mycology.

Avena↗
PubMed1981

Enzyme thermistor analysis of penicillin in standard solutions and in fermentation broth.

Immobilized penicillinase was applied in an enzyme thermistor for calorimetric analysis of samples containing penicillin G. Standard solutions as well as extracts from fermentation broth were analyzed. The enzyme was applied bound either to porous glass or, when dealing with crude preparations, to the inner surface of nylon tubing. In the fermentation system studied, high concentrations of penicillin were present, thus allowing dilution to reduce the influence of the composition of the medium on the analysis. The useful linear concentration range was from 0.1 to 100 mM. The coefficient of correlation between analytical results obtained with the present method and those from conventional assays was 0.997.

Journal Article↗