CORDIS fournit des liens vers les livrables publics et les publications des projets HORIZON.
Les liens vers les livrables et les publications des projets du 7e PC, ainsi que les liens vers certains types de résultats spécifiques tels que les jeux de données et les logiciels, sont récupérés dynamiquement sur OpenAIRE .
Livrables
A questionnaire was distributed to collect information on the main radiation parameters of THz sources, which are currently in use at various laboratories worldwide.
The questionnaire collected information concerning:
- The main radiation parameters of THz sources (e.g. frequency range, power level, modulation).
- Biological and potential biomedical applications of THz sources.
- Exposure conditions (if any) of technical personnel.
- Safety measurements or precautions currently adopted.
The questionnaire also requested information about any risk perceived in using THz-radiation.
The questionnaire was designed by the THz-BRIDGE consortium members and was delivered to a list of about hundred research groups in occasion of several conferences. The questionnaire was also put in an interactive form on the project web-page. Compiled forms have been collected over an 18-month period and the statistical basis has been continuously updated.
The survey was mainly designed to look at safety issues at specific occupational sites. These were defined as sites where THz sources are employed or in development. Due to the early stage of THz technology these are to be mainly found in Universities or Research facilities. The questionnaire collected data of currently used terahertz sources for the first time.
As of February 2004 25 groups have returned a completed questionnaire providing information about 35 different THz systems. 37% of the responses came from the European Union; the remaining contributions came from the United States, Japan and Russia. It is planned to continue to update the statistical basis with support from the EMF-NET Coordination Action.
SUMMARY
- 25 groups returned data (1 off these was rejected as they submitted laser parameters rather than thz).
-- Most of these groups are using terahertz radiation generated by short pulse solid-state lasers;
-- They are mostly interested in source development and biomedical applications;
-- Data has been provided on 34 systems
- 5 groups expressed concerns of exposure to THz radiation.
- Mainly FEL groups take precaution against THz radiation in the frame of more severe shielding requirements of the accelerators on which they are based.
- It appears currently that there are no records taken of occupational workers exposure to THz radiation.
The spectroscopic database (SDB) is intended to provide information on the spectral characteristic of a wide variety of biological systems both to project partners and to the scientific community. According to the THz-BRIDGE contract such a database is of public domain, in order to share the results of spectroscopic experiments with the scientific community.
The database can be accessed from the project home page (http://www.frascati.enea.it/THz-BRIDGE). Due to the not too large dimension of the database, its logical structure is designed utilizing a sequential model. A future improvement will give rise to a new relational model for the database.
The database currently includes about 50 different spectra of biologal samples.
Following the workplan, we have performed systematic spectroscopic investigations on a variety of material to be used by the various groups involved in the project in the construction of standardised spectroscopic chambers. A commercial plastic-ware material widely used in biology is polystyrene, which exhibits excellent optical properties in the wavelength range between 200um and 3mm (frequency range 1.5THz to 100GHz).
Specific measurements were carried out by measuring both the transmission and the complex dielectric constant over a wide spectral range. Further spectroscopic investigations were carried out on other materials, like ZnTe, which may be used as windows of spectroscopic cells in the high frequency range between 500 and 10000cm{-1} (15 - 300THz).
Optical transmission and reflection measurements are performed using two FTIR spectrometers (Bruker IFS 113v, Biorad) in the range from 5 to 15000 cm{-1} and a Mach-Zehnder interferometer in the range from 2 to 40cm{-1} which employs twelve different Backward Wave Oscillators as tunable monochromatic continuous wave sources.
The exploration of biological effects induced by THz radiation was aimed to provide information regarding basic data and safety issues involved in employing THz radiation in medical and technological applications. This involved the employment of different biological targets including DNA bases, model membranes (liposomes), human lymphocytes, primary human keratinocytes and a neuronal cell line.
The THz-induced biological end-points studied were alteration of membrane permeability of liposomes, induction of genotoxicity in lymphocytes as well as studying changes in cell activity, differentiation and barrier function in keratinocytes and neuronal cells. The results indicate that under various exposure conditions no biological effects could be detected. However, under some specific conditions of exposure, change in membrane permeability of liposomes was detected and an induction of genetoxicity was observed to occur in lymphocytes.
These studies suggest that medical imaging employing appropriate exposure parameters is probably unharmful at least for single exposures. Moreover, since some effects were observed to be induced by the THz radiation at a relatively low intensity when compared to the limits set by the ICNIRP for exposure, these studies should be extended to establish more accurate dose-response relationships. This is expected to provide in future improved guidelines of exposure.
Recherche de données OpenAIRE...
Une erreur s’est produite lors de la recherche de données OpenAIRE
Aucun résultat disponible