155 research outputs found
Extensive study of the electron donor 1,1,4,4-tetrathiabutadiene (TTB) and of its charge transfer crystal with TCNQ
No full textIn the spirit of the renewed interest in mixed stack charge-transfer (CT) crystals, made up by alternating π electron-donor and acceptor molecules, we focus attention on a forgotten donor, 1,1,4,4-tetrathiabutadiene (TTB), synthesized more than 35 years ago. We present a spectroscopic and computational characterization of the neutral TTB, and fully characterize the CT crystal with TCNQ. TTB-TCNQ is a mixed stack crystal, with limited degree of CT (about 0.1), despite TTB electron donating strength is only a little smaller than that of the famous TTF. This finding is explained by the small value of the Madelung energy, that we evaluate by a well tested computational approach.We thank the late Prof. Daniel J. Sandman for his help with the synthesis. We acknowledge the support of the EU with ERC StG2012-306826e-GAMES and of the MINECO of the Spanish Government (CTQ2016- 80030-R and SEV-2015-0496).Peer reviewe
‐Heptacene: Synthesis and In Situ Characterization
No full textn-peri-Acenes (n-PAs) have gained interest as model systems of zigzag-edged graphene nanoribbons for potential applications in nanoelectronics and spintronics. However, the synthesis of n-PAs larger than peri-tetracene remains challenging because of their intrinsic open-shell character and high reactivity. Presented here is the synthesis of a hitherto unknown n-PA, that is, peri-heptacene (7-PA), in which the reactive zigzag edges are kinetically protected with eight 4-tBu-C6H4 groups. The formation of 7-PA is validated by high-resolution mass spectrometry and in situ FT-Raman spectroscopy. 7-PA displays a narrow optical energy gap of 1.01 eV and exhibits persistent stability (t1/2≈25 min) under inert conditions. Moreover, electron-spin resonance measurements and theoretical studies reveal that 7-PA exhibits an open-shell feature and a significant tetraradical character. This strategy could be considered a modular approach for the construction of next-generation (3 N+1)-PAs (where N≥3). © 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH Gmb
Delineation of groundwater recharge zones in lateritic terrains using geospatial techniques
No full textAbstract This study attempts to narrow down the groundwater potential zones in a river basin where laterites form the major aquifer rock. The study is attempted in the Ithikkara River Basin (IRB), located in the southern Western Ghats of Kerala, India. Groundwater scarcity is a pressing issue in this region, warranting effective management of the groundwater resources. To address this important problem, satellite data (Landsat 8 OLI, SRTM DEM) and geospatial techniques were employed to assess the hydrogeological potential. Various thematic maps such as geology, geomorphology, drainage density, lineament density, slope, land use, relative relief and mean depth to water table were integrated in the spatial platform to derive suitable sites for artificial recharging. The thematic layers were subjected to weighted overlay analysis using QGIS and SAGA GIS to delineate groundwater potential area. The resultant map has been validated with well yield data obtained from the Central Ground water Board, Government of India and field data. It is found that the lower reaches along the western portions of the basin is more suitable for artificial recharging of aquifers, owing to the presence of sedimentary rocks and valley fills
Optimisation de la spectroscopie laser dans un jet gazeux supersonique pour la mesure à haute résolution des actinides
No full textLa Ligne Basse Energie du Super Separator Spectrometer (S3-LEB) est un dispositif expérimental qui a pour objectif de produire des faisceaux d'ions radioactifs de basse énergie dans le cadre de l'installation GANIL-SPIRAL2. Ce travail de thèse traite des premiers résultats hors ligne de S3-LEB incluant les premières mesures de spectroscopie laser dans la cellule à gaz et dans le jet gazeux supersonique, la détermination de l'efficacité de transport des ions produits par ionisation laser résonante, depuis la cellule à gaz à travers la chaîne RFQ, et les mesures de temps de vol avec le spectromètre de masse PILGRIM. Les mesures ont été effectuées en utilisant de l'erbium, introduit par évaporation à partir d'un filament chauffé dans l'environnement gazeux. Les résultats de spectroscopie laser présentés comprennent une caractérisation de l'élargissement de la largeur spectrale due à la pression dans la cellule gazeuse, la validation du principe des mesures du décalage isotopique et de la structure hyperfine dans le jet gazeux. Ce travail démontre le potentiel unique de cette installation pour mener à bien les futures expériences en ligne. L'ionisation et la spectroscopie laser hors ligne de l'uranium et de l'américium de la série des actinides ont également été abordées. Ce travail de thèse comprend également des développements techniques tels que la mise en œuvre des systèmes laser en titane saphir et la construction d’un banc d'essai dédié aux tests des fenêtres d'entrées pour S3-LEB. Un système laser à faisceau continu pompé par diode a été construit pour une application de spectroscopie laser à haute résolution. Les mesures de spectroscopie laser de l'américium effectuées à RISIKO montrent le potentiel d'un tel système laser pour effectuer des mesures à haute résolution dans les actinides.The Super Separator Spectrometer-Low Energy Branch (S3-LEB) is a low-energy radioactive ion beam experimental setup under commissioning as part of the GANIL-SPIRAL2 facility. In this thesis work, the off-line commissioning of the S3-LEB setup, including first laser spectroscopy measurements in both the gas cell and the supersonic gas jet, the determination of the transport efficiency of laser ions from the gas cell through the RFQ chain, and time-of-flight measurements with the multi-reflection time-of-flight mass spectrometer PILGRIM are discussed. The measurements were performed using erbium, introduced by evaporation from a heated filament in the gas environment. The reported laser spectroscopy results include a characterization of the pressure broadening in the gas cell and proof-of principle isotope shift and hyperfine-structure measurements. This work proves the potential of the setup to conduct the future online tests, where erbium is chosen as the first case for online commissioning. Offline laser ionization and spectroscopy of uranium and americium from the actinide series have been discussed. This thesis work also includes technical developments such as the implementation of the titanium sapphire laser systems and a dedicated entrance window test bench for the S3-LEB. A continuous wave diode-pumped laser system has been built for high-resolution laser spectroscopy application. Americium laser spectroscopy measurements at RISIKO present the potential of such a laser system in performing high-resolution measurements in actinides
Electronic Design of an Analog Equalizer for a Bone Conduction Stethoscope
No full textAbstract
The necessity and interest of audiologists to finely tune and customize sound frequencies according to individual patient needs, has inspired us to develop and integrate an equalizer to a bone conduction stethoscope. The project designs an analog amplifier equalizer circuit that is used for volume control and frequency selection. It captures sounds from the skull bone with the help of a skin microphone hoping to provide audiologists a flexible tool that can isolate specific frequency bands for analysis, auditory experience diagnosis and troubleshooting of bone conduction hearing aids. The switching options designed on the equalizer has bandpass filters for the audiometric frequencies with the possibility to focus the listening range to both low and high frequencies and thereby encourage audiologists to select the desired ranges of inspection. The project plan was designed to use the electronic features to categorize audio spectrum into bass (125 Hz to 1 kHz), wide (125 Hz to 8 kHz) and treble (1-8 kHz) for testing. The test is done on two subjects with the use of a skin microphone having a strategy to check one’s own voice to understand the perception of booming effect, crispness and clarity along with normal speech auditory range of bone conduction voice. The test subjects also experimented by hearing each other’s voice through the equalizer to understand the audio spectrum as mimicked in normal hearing conditions as a reference. The results showed that the auditory experience was in sync with the theoretical expectations. To conclude, the design and testing of the prototype showed that it is a promising tool for audiologists in near future
Optimisation de la spectroscopie laser dans un jet gazeux supersonique pour la mesure à haute résolution des actinides
No full textThe Super Separator Spectrometer-Low Energy Branch (S3-LEB) is a low-energy radioactive ion beam experimental setup under commissioning as part of the GANIL-SPIRAL2 facility. In this thesis work, the off-line commissioning of the S3-LEB setup, including first laser spectroscopy measurements in both the gas cell and the supersonic gas jet, the determination of the transport efficiency of laser ions from the gas cell through the RFQ chain, and time-of-flight measurements with the multi-reflection time-of-flight mass spectrometer PILGRIM are discussed. The measurements were performed using erbium, introduced by evaporation from a heated filament in the gas environment. The reported laser spectroscopy results include a characterization of the pressure broadening in the gas cell and proof-of principle isotope shift and hyperfine-structure measurements. This work proves the potential of the setup to conduct the future online tests, where erbium is chosen as the first case for online commissioning. Offline laser ionization and spectroscopy of uranium and americium from the actinide series have been discussed. This thesis work also includes technical developments such as the implementation of the titanium sapphire laser systems and a dedicated entrance window test bench for the S3-LEB. A continuous wave diode-pumped laser system has been built for high-resolution laser spectroscopy application. Americium laser spectroscopy measurements at RISIKO present the potential of such a laser system in performing high-resolution measurements in actinides.La Ligne Basse Energie du Super Separator Spectrometer (S3-LEB) est un dispositif expérimental qui a pour objectif de produire des faisceaux d'ions radioactifs de basse énergie dans le cadre de l'installation GANIL-SPIRAL2. Ce travail de thèse traite des premiers résultats hors ligne de S3-LEB incluant les premières mesures de spectroscopie laser dans la cellule à gaz et dans le jet gazeux supersonique, la détermination de l'efficacité de transport des ions produits par ionisation laser résonante, depuis la cellule à gaz à travers la chaîne RFQ, et les mesures de temps de vol avec le spectromètre de masse PILGRIM. Les mesures ont été effectuées en utilisant de l'erbium, introduit par évaporation à partir d'un filament chauffé dans l'environnement gazeux. Les résultats de spectroscopie laser présentés comprennent une caractérisation de l'élargissement de la largeur spectrale due à la pression dans la cellule gazeuse, la validation du principe des mesures du décalage isotopique et de la structure hyperfine dans le jet gazeux. Ce travail démontre le potentiel unique de cette installation pour mener à bien les futures expériences en ligne. L'ionisation et la spectroscopie laser hors ligne de l'uranium et de l'américium de la série des actinides ont également été abordées. Ce travail de thèse comprend également des développements techniques tels que la mise en œuvre des systèmes laser en titane saphir et la construction d’un banc d'essai dédié aux tests des fenêtres d'entrées pour S3-LEB. Un système laser à faisceau continu pompé par diode a été construit pour une application de spectroscopie laser à haute résolution. Les mesures de spectroscopie laser de l'américium effectuées à RISIKO montrent le potentiel d'un tel système laser pour effectuer des mesures à haute résolution dans les actinides
Advancement in Age Estimation in Forensic Science Through Molecular Fingerprinting Techniques – A Review Paper
No full textDactyloscopy has long been used for personal identification from the latent fingerprint residues, capable of providing an insight into various factors of an individual, such as age, sex, habits and lifestyle. Various studies have been conducted to precisely identify the changes in activity of sweat glands and the chemical breakdown of fingerprint residues with respect to time. However, a reliable method for accurately estimating or approximating the age of the fingerprint donor is yet to be established. The emerging field of molecular fingerprinting analyses latent fingerprint sweat residue and profiles the components present in it, which aids in personal identification as an individualistic marker specific to each individual. This review article highlights the advancements in estimating the age of the fingerprint donor from latent fingerprint residue and addresses the technical and technological research gaps in the timeline of molecular fingerprinting techniques, as this method holds potential in aiding forensic investigation and criminal profiling from the fingerprints retrieved from the scene of crime
Controllability of a Class of Heterogeneous Networked Systems
No full textThis paper examines the controllability of a class of heterogeneous networked systems where the nodes are linear time-invariant systems (LTI), and the network topology is triangularizable. The literature contains necessary and sufficient conditions for the controllability of such systems where the control input matrices are identical in each node. Here, we extend this result to a class of heterogeneous systems where the control input matrices are distinct in each node. Additionally, we discuss the controllability of a more general system with triangular network topology and obtain necessary and sufficient conditions for controllability. Theoretical results are supplemented with numerical examples
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