Search

Your search keyword '"Viret, V."' showing total 16 results
Start Over Author "Viret, V."
16 results on '"Viret, V."'

4. Influences of a high excitation frequency (70 MHz) in the glow discharge technique on the process plasma and the properties of hydrogenated amorphous silicon

Author

Finger, F., Kroll, U., Viret, V., Shah, A., Beyer, W., Tang, X.-M., Weber, Joseph, Howling, A., and Hollenstein, Ch.

Subjects
Thin films -- Research, Amorphous semiconductors -- Research, Semiconductors -- Plasma effects, Physics
Abstract

Hydrogen evolution, elastic recoil detection analysis and infrared spectroscopy were used to investigate the effect of a high excitation frequency in the glow discharge technique on the process plasma and the characteristics of hydrogenated amorphous silicon. The results showed that as the substrate temperature decreased from 280 to 50 degrees celsius, significant changes occured in the structural and electrical properties of thin films prepared at the frequency of 13.56 MHz.

Published
1992

5. Influences of a high excitation frequency (70 MHz) in the glow discharge technique on the process plasma and the properties of hydrogenated amorphous silicon

Author

Finger, F., Kroll, U., Viret, V., Shah, Arvind, Beyer, W., Tang, X.-M., Weber, J., Howling, A. A., Hollenstein, C., Finger, F., Kroll, U., Viret, V., Shah, Arvind, Beyer, W., Tang, X.-M., Weber, J., Howling, A. A., and Hollenstein, C.

Abstract

Hydrogenated amorphous silicon has been prepared at a plasma excitation frequency in the very-high-frequency band at 70 MHz with the glow discharge technique at substrate temperatures between 280 and 50 °C. The structural properties have been studied using hydrogen evolution, elastic recoil detection analysis, and infrared spectroscopy. The films were further characterized by dark and photoconductivity and by photothermal deflection spectroscopy. With respect to films prepared at the conventional frequency of 13.56 MHz considerable differences concerning the electronic and structural properties are observed as the substrate temperature is decreased from 280 to 50 °C. Down to a substrate temperature of 150 °C the electronic film properties change only a little and the total hydrogen content cH and the degree of microstructure that can be directly correlated to cH increase only moderately. Below 150 °C the electronic properties deteriorate in the usual manner but still the total hydrogen content does not exceed 21 at. % even at a substrate temperature of 50 °C. It is argued that the influence of the higher excitation frequency on the plasma and on the growth kinetics plays a key role in this context by allowing a highly effective dissociation of the process gas with the maximum ion energies remaining at low levels. It is concluded that deposition processes at higher excitation frequencies can have important technological implications by allowing a decrease of the deposition temperature without losses in the material quality.

Published
2008

9. Evaluation of an Immunochromatographic Test for Rapid and Reliable Serodiagnosis of Human Tularemia and Detection of Francisella tularensis-Specific Antibodies in Sera from Different Mammalian Species

Author

Splettstoesser, W., Guglielmo-Viret, V., Seibold, E., and Thullier, P.

Abstract

ABSTRACTTularemia is a highly contagious infectious zoonosis caused by the bacterial agent Francisella tularensis. Serology is still considered to be a cornerstone in tularemia diagnosis due to the low sensitivity of bacterial culture and the lack of standardization in PCR methodology for the direct identification of the pathogen. We developed a novel immunochromatographic test (ICT) to efficiently detect F. tularensis-specific antibodies in sera from humans and other mammalian species (nonhuman primate, pig, and rabbit). This new tool requires none or minimal laboratory equipment, and the results are obtained within 15 min. When compared to the method of microagglutination, which was shown to be more specific than the enzyme-linked immunosorbent assay, the ICT had a sensitivity of 98.3% (58 positive sera were tested) and a specificity of 96.5% (58 negative sera were tested) on human sera. On animal sera, the overall sensitivity was 100% (22 positive sera were tested) and specificity was also 100% (70 negative sera were tested). This rapid test preferentially detects IgG antibodies that may occur early in the course of human tularemia, but further evaluation with human sera is important to prove that the ICT can be a valuable field test to support a presumptive diagnosis of tularemia. The ICT can also be a useful tool to monitor successful vaccination with subunit vaccines or live vaccine strains containing lipopolysaccharide (e.g., LVS) and to detect seropositive individuals or animals in outbreak situations or in the context of epidemiologic surveillance programs in areas of endemicity as recently recommended by the World Health Organization.

Published
2010
Full Text
View/download PDF

10. Influences of a High-Excitation Frequency (70 Mhz) in the Glow-Discharge Technique on the Process Plasma and the Properties of Hydrogenated Amorphous-Silicon

Author

Finger, F., Kroll, U., Viret, V., Shah, A., Beyer, W., Tang, X. M., Weber, J., Howling, A., and Hollenstein, C.

Abstract

Hydrogenated amorphous silicon has been prepared at a plasma excitation frequency in the very-high-frequency band at 70 MHz with the glow discharge technique at substrate temperatures between 280 and 50-degrees-C. The structural properties have been studied using hydrogen evolution, elastic recoil detection analysis, and infrared spectroscopy. The films were further characterized by dark and photoconductivity and by photothermal deflection spectroscopy. With respect to films prepared at the conventional frequency of 13.56 MHz considerable differences concerning the electronic and structural properties are observed as the substrate temperature is decreased from 280 to 50-degrees-C. Down to a substrate temperature of 150-degrees-C the electronic film properties change only a little and the total hydrogen content c(H) and the degree of microstructure that can be directly correlated to c(H) increase only moderately. Below 150-degrees-C the electronic properties deteriorate in the usual manner but still the total hydrogen content does not exceed 21 at.% even at a substrate temperature of 50-degrees-C. It is argued that the influence of the higher excitation frequency on the plasma and on the growth kinetics plays a key role in this context by allowing a highly effective dissociation of the process gas with the maximum ion energies remaining at low levels. It is concluded that deposition processes at higher excitation frequencies can have important technological implications by allowing a decrease of the deposition temperature without losses in the material quality.

11. Influences of a high excitation frequency (70 MHz) in the glow discharge technique on the process plasma and the properties of hydrogenated amorphous silicon

Author

Finger, F., Kroll, U., Viret, V., Shah, Arvind, Beyer, W., Tang, X.-M., Weber, J., Howling, A. A., Hollenstein, C., Finger, F., Kroll, U., Viret, V., Shah, Arvind, Beyer, W., Tang, X.-M., Weber, J., Howling, A. A., and Hollenstein, C.

Abstract

Hydrogenated amorphous silicon has been prepared at a plasma excitation frequency in the very-high-frequency band at 70 MHz with the glow discharge technique at substrate temperatures between 280 and 50 °C. The structural properties have been studied using hydrogen evolution, elastic recoil detection analysis, and infrared spectroscopy. The films were further characterized by dark and photoconductivity and by photothermal deflection spectroscopy. With respect to films prepared at the conventional frequency of 13.56 MHz considerable differences concerning the electronic and structural properties are observed as the substrate temperature is decreased from 280 to 50 °C. Down to a substrate temperature of 150 °C the electronic film properties change only a little and the total hydrogen content cH and the degree of microstructure that can be directly correlated to cH increase only moderately. Below 150 °C the electronic properties deteriorate in the usual manner but still the total hydrogen content does not exceed 21 at. % even at a substrate temperature of 50 °C. It is argued that the influence of the higher excitation frequency on the plasma and on the growth kinetics plays a key role in this context by allowing a highly effective dissociation of the process gas with the maximum ion energies remaining at low levels. It is concluded that deposition processes at higher excitation frequencies can have important technological implications by allowing a decrease of the deposition temperature without losses in the material quality.

15. Development and comparison of two immunoassay formats for rapid detection of botulinum neurotoxin type A.

Author

Attrée O, Guglielmo-Viret V, Gros V, and Thullier P

Subjects
Animals, Antibodies, Monoclonal immunology, Biotinylation, Botulinum Toxins, Type A analysis, Botulinum Toxins, Type A immunology, Chromatography methods, Chromatography, Affinity methods, Cross Reactions immunology, Flour analysis, Gold chemistry, Horseradish Peroxidase chemistry, Humans, Immunoassay instrumentation, Immunoassay methods, Mice, Milk chemistry, Rabbits, Reagent Strips chemistry, Reproducibility of Results, Sensitivity and Specificity, Streptavidin chemistry, Talc chemistry, Botulinum Toxins, Type A blood, Botulism diagnosis
Abstract

We have evaluated two formats of immunoassays for the rapid detection of Clostridium botulinum neurotoxin type A (BoNT/A), in assay buffer and various matrices (human serum and nasal swabs, fresh milk, sugar, flour and talcum). The two formats, a vertical-flow strip immunochromatography (ICT) and a small disposable immunoaffinity column (IAC), were selected because they are both rapid and readily usable in the field without sophisticated equipment. We utilised the same critical reagents to develop and optimise both assays, making it possible to compare the corresponding technologies on the same toxin preparations, without interference due to the properties of the antibodies. Results were interpreted using a standard statistical test (ANOVA) and showed little difference of sensitivity between matrices. Though both assays were completed in 40 min, the sensitivity of the IAC, evaluated at 0.45 pM (5 mouse LD50 units/ml), was 40 to 80 times better than that of the ICT. Furthermore, the sensitivity of the IAC assay was improved to 0.09 pM (1 mouse LD50 unit/ml) when performed on a 5-ml volume of human serum. Thus, the IAC appears to be one of the most sensitive and rapid assays for the detection of BoNT/A reported to date and, because it is also highly transportable, it is amongst the best suited for field diagnosis of BoNT/A poisoning.

Published
2007
Full Text
View/download PDF

16. An immunochromatographic test for the diagnosis of ricin inhalational poisoning.

Author

Guglielmo-Viret V, Splettstoesser W, and Thullier P

Subjects
Aerosols, Animals, Antibodies immunology, Chromatography methods, Inhalation Exposure adverse effects, Mice, Ricin immunology, Ricin poisoning, Sensitivity and Specificity, Immunologic Tests methods, Inhalation Exposure analysis, Ricin analysis
Abstract

Introduction: Aerosolized ricin is a feared bioweapon for which no diagnostic protocol is currently available., Methods: We obtained antibodies to develop an immunochromatographic test (ICT) that would be part of such a protocol., Results: Our ICT, that can be read with the naked eye, has a sensitivity of 1 ng ricin/mL buffer, without enhancement, making it the most sensitive rapid test available for this toxin as far as we know. Its dynamic range extends to 10 microg/mL, with a plateau from 10 to at least 250 microg/mL (no "hook effect"), and it has limited cross-reactivity with other lectins., Discussion: Calculated from experimental and animal data, sampling with nasal swabs and testing with the devised ICT should give more than a thousand times the sensitivity required to diagnose ricin inhalational poisoning. Such a margin is particularly valuable in the absence of clinical data., Conclusion: This cost-effective and easy to use diagnostic tool could assist in the diagnosis of inhalational exposure from ricin aerosols.

Published
2007
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results