9 research outputs found
The effects of two different recovery postures during high intensity interval training
The purpose of this study was to examine the effects of two different recovery postures, hands on head (HH) and hands on knees (HK), as a form of immediate recovery from high intensity interval training (HIIT). Furthermore, the study examined whether the two recovery postures influenced subsequent power performance in a Wingate Anaerobic Test. Twenty subjects were included and testing sessions were randomized for each subject. Each subject performed four intervals of 4 minutes of running (4X4) with three minutes of recovery between each running interval. During each three minute recovery interval, measurements recorded included: HRR for the first minute and then volume of carbon dioxide (VCO2) and tidal volume (VT). After the last recovery interval, each subject performed a Wingate Anaerobic Test. The results show improved HRR (p \u3c .001) and greater VT (p = .008) with HK when compared to HH (53 versus 31 beats per minute for HRR and 1.44 versus 1.34 L/minute VT respectively). However there was no difference in VCO2 (1.13 L/min with HK and 1.03 L/min with HH) or subsequent mean power output on the Wingate Anaerobic Test (503 Watts with HK and 498 Watts with HH) between both groups. HK posture may be more beneficial than the popularly advocated HH posture as a form of immediate recovery from HIIT
Structuration chimique induite et contrĂŽlĂ©e par impact dâĂ©lectrons lents sur films molĂ©culaires supportĂ©s
Self-Assembled Monolayers (SAMs) are good candidates to develop molecular platforms with controlled physico-chemical properties. A SAM is an ordered monolayer of bi-functionnal molecules. These molecules consist of an adjustable terminal function, separated from a headgroup by a chosen spacer chain. Thus, SAMs properties can be adjusted for the development of molecular electronic systems or (bio)-chemical sensors. Furthermore, additional chemical structuration can be induced by irradiation.Most current methods of irradiation involve high energy particles. The induced damages result from several competitive mechanisms (ionisations, excitations, dissociations). In this thesis, low energy electrons (0-20 eV) are used as primary particles, and the interaction processes between electrons and SAMs are studied in order to identify electron attachment resonances. At the associated energies, selective and effective dissociative processes can be induced to propose irradiation strategies leading to controlled and optimized chemical modifications.Model SAMs of thiols on gold are studied by a vibrational spectroscopy technique of strong surface sensibility, high resolution electron energy loss spectroscopy (HREELS). It allows at the same time to characterize SAMs and to probe electron-molecule interaction processes. The result obtained deal with : 1)Aromatic model SAMs of Terphenyl-thiol (HS-(CâHâ)â-CâHâ
), which can be stabilized by cross-linking under irradiation. Induced reactive processes at 1, 6 and 50 eV were compared and opposed, thanks to an advanced vibrational characterization of the SAM before and after irradiation, and by paying a particular attention to the stretching mode Îœ(CH) behaviour.2)Mercaptoundecanoic acid SAMs (HS-(CHâ)â â -COOH), whose terminal functions allow for example the peptide anchoring. The interface SAM / environment (COO-/COOH, residual water) was characterized thanks to the strong sensitivity of the stretching modes Îœ(OH) to hydrogen bonding. The approach that was developped can be easily transposed to other systems.Les mono-couches auto-assemblĂ©es (SAMs) sont des systĂšmes de choix pour le dĂ©veloppement de plateformes molĂ©culaires aux propriĂ©tĂ©s physico-chimiques contrĂŽlĂ©es. Il sâagit de monocouches organisĂ©es de molĂ©cules bi-fonctionnelles. Ces molĂ©cules se composent dâune fonction terminale modulable, sĂ©parĂ©e dâun groupement dâancrage par un espaceur adaptĂ©. Ainsi, les propriĂ©tĂ©s des SAMs peuvent ĂȘtre ajustĂ©es pour le dĂ©veloppement de systĂšmes Ă©lectroniques molĂ©culaires ou de capteurs (bio)-chimiques. De plus, des structurations chimiques supplĂ©mentaires peuvent ĂȘtre induites par irradiation.Les mĂ©thodes dâirradiation les plus courantes impliquent des particules de haute Ă©nergie. Les dommages induits rĂ©sultent de plusieurs mĂ©canismes en compĂ©tition (ionisations, excitations, dissociations). Dans cette thĂšse, les Ă©lectrons lents (0-20 eV) sont utilisĂ©s comme particules primaires, et les processus dâinteraction Ă©lectron-SAM sont Ă©tudiĂ©s afin dâidentifier les rĂ©sonances dâattachement Ă©lectronique. Aux Ă©nergies concernĂ©es, des processus dissociatifs sĂ©lectifs et efficaces peuvent ĂȘtre mis Ă profit pour proposer des stratĂ©gies dâirradiation menant Ă des modifications chimiques contrĂŽlĂ©es et optimisĂ©es.Des SAMs modĂšles de thiols sur or sont Ă©tudiĂ©es par une technique de spectroscopie vibrationnelle de forte sensibilitĂ© de surface, la spectroscopie de perte dâĂ©nergie dâĂ©lectrons lents (HREELS). Elle permet Ă la fois de caractĂ©riser les SAMs et de sonder les processus d'interaction Ă©lectron-molĂ©cule. Les rĂ©sultats obtenus concernent les : 1)SAMs aromatiques modĂšles de terphĂ©nylthiol (HS-(CâHâ)â-CâHâ
), stabilisables par rĂ©ticulation sous irradiation. Une caractĂ©risation vibrationnelle poussĂ©e de la SAM avant et aprĂšs irradiation, en portant une attention particuliĂšre au comportement des modes dâĂ©longation Îœ(CH), a permis dâopposer les processus de rĂ©activitĂ© induite Ă 1, 6 et 50 eV.2)SAMs dâacide mercaptoundĂ©canoĂŻque (HS-(CHâ)â â -COOH), les fonctions acides terminales permettant par exemple le greffage de peptides. Lâinterface SAM / environnement (COO-/COOH, eau rĂ©siduelle) a Ă©tĂ© caractĂ©risĂ©e grĂące Ă la forte sensibilitĂ© des modes dâĂ©longation Îœ(OH) aux liaisons hydrogĂšne. La dĂ©marche mise en place peut ĂȘtre facilement transposĂ©e Ă dâautres systĂšmes
Chemical structuration induced and controlled by low-energy electron impact on supported molecular films
Les mono-couches auto-assemblĂ©es (SAMs) sont des systĂšmes de choix pour le dĂ©veloppement de plateformes molĂ©culaires aux propriĂ©tĂ©s physico-chimiques contrĂŽlĂ©es. Il sâagit de monocouches organisĂ©es de molĂ©cules bi-fonctionnelles. Ces molĂ©cules se composent dâune fonction terminale modulable, sĂ©parĂ©e dâun groupement dâancrage par un espaceur adaptĂ©. Ainsi, les propriĂ©tĂ©s des SAMs peuvent ĂȘtre ajustĂ©es pour le dĂ©veloppement de systĂšmes Ă©lectroniques molĂ©culaires ou de capteurs (bio)-chimiques. De plus, des structurations chimiques supplĂ©mentaires peuvent ĂȘtre induites par irradiation.Les mĂ©thodes dâirradiation les plus courantes impliquent des particules de haute Ă©nergie. Les dommages induits rĂ©sultent de plusieurs mĂ©canismes en compĂ©tition (ionisations, excitations, dissociations). Dans cette thĂšse, les Ă©lectrons lents (0-20 eV) sont utilisĂ©s comme particules primaires, et les processus dâinteraction Ă©lectron-SAM sont Ă©tudiĂ©s afin dâidentifier les rĂ©sonances dâattachement Ă©lectronique. Aux Ă©nergies concernĂ©es, des processus dissociatifs sĂ©lectifs et efficaces peuvent ĂȘtre mis Ă profit pour proposer des stratĂ©gies dâirradiation menant Ă des modifications chimiques contrĂŽlĂ©es et optimisĂ©es.Des SAMs modĂšles de thiols sur or sont Ă©tudiĂ©es par une technique de spectroscopie vibrationnelle de forte sensibilitĂ© de surface, la spectroscopie de perte dâĂ©nergie dâĂ©lectrons lents (HREELS). Elle permet Ă la fois de caractĂ©riser les SAMs et de sonder les processus d'interaction Ă©lectron-molĂ©cule. Les rĂ©sultats obtenus concernent les : 1) SAMs aromatiques modĂšles de terphĂ©nylthiol (HS-(CâHâ)â-CâHâ
), stabilisables par rĂ©ticulation sous irradiation. Une caractĂ©risation vibrationnelle poussĂ©e de la SAM avant et aprĂšs irradiation, en portant une attention particuliĂšre au comportement des modes dâĂ©longation Îœ(CH), a permis dâopposer les processus de rĂ©activitĂ© induite Ă 1, 6 et 50 eV.2) SAMs dâacide mercaptoundĂ©canoĂŻque (HS-(CHâ)â â -COOH), les fonctions acides terminales permettant par exemple le greffage de peptides. Lâinterface SAM / environnement (COO-/COOH, eau rĂ©siduelle) a Ă©tĂ© caractĂ©risĂ©e grĂące Ă la forte sensibilitĂ© des modes dâĂ©longation Îœ(OH) aux liaisons hydrogĂšne. La dĂ©marche mise en place peut ĂȘtre facilement transposĂ©e Ă dâautres systĂšmes.Self-Assembled Monolayers (SAMs) are good candidates to develop molecular platforms with controlled physico-chemical properties. A SAM is an ordered monolayer of bi-functionnal molecules. These molecules consist of an adjustable terminal function, separated from a headgroup by a chosen spacer chain. Thus, SAMs properties can be adjusted for the development of molecular electronic systems or (bio)-chemical sensors. Furthermore, additional chemical structuration can be induced by irradiation.Most current methods of irradiation involve high energy particles. The induced damages result from several competitive mechanisms (ionisations, excitations, dissociations). In this thesis, low energy electrons (0-20 eV) are used as primary particles, and the interaction processes between electrons and SAMs are studied in order to identify electron attachment resonances. At the associated energies, selective and effective dissociative processes can be induced to propose irradiation strategies leading to controlled and optimized chemical modifications.Model SAMs of thiols on gold are studied by a vibrational spectroscopy technique of strong surface sensibility, high resolution electron energy loss spectroscopy (HREELS). It allows at the same time to characterize SAMs and to probe electron-molecule interaction processes. The result obtained deal with : 1) Aromatic model SAMs of Terphenyl-thiol (HS-(CâHâ)â-CâHâ
), which can be stabilized by cross-linking under irradiation. Induced reactive processes at 1, 6 and 50 eV were compared and opposed, thanks to an advanced vibrational characterization of the SAM before and after irradiation, and by paying a particular attention to the stretching mode Îœ(CH) behaviour.2) Mercaptoundecanoic acid SAMs (HS-(CHâ)â â -COOH), whose terminal functions allow for example the peptide anchoring. The interface SAM / environment (COO-/COOH, residual water) was characterized thanks to the strong sensitivity of the stretching modes Îœ(OH) to hydrogen bonding. The approach that was developped can be easily transposed to other systems
Electron Processing at 50 eV of Terphenylthiol Self-Assembled Monolayers: Contributions of Primary and Secondary Electrons
International audienceAromatic self-assembled monolayers (SAMs) can serve as platforms for development of supramolecular assemblies driven by surface templates. For many applications, electron processing is used to locally reinforce the layer. To achieve better control of the irradiation step, chemical transformations induced by electron impact at 50 eV of terphenylthiol SAMs are studied, with these SAMs serving as model aromatic SAMs. High-resolution electron energy loss spectroscopy (HREELS) and electron-stimulated desorption (ESD) of neutral fragment measurements are combined to investigate electron-induced chemical transformation of the layer. The decrease of the CH stretching HREELS signature is mainly attributed to dehydrogenation, without a noticeable hybridization change of the hydrogenated carbon centers. Its evolution as a function of the irradiation dose gives an estimate of the effective hydrogen content loss cross-section, Ï = 2.7â4.7 Ă 10 â17 cm 2. Electron impact ionization is the major primary mechanism involved, with the impact electronic excitation contributing only marginally. Therefore, special attention is given to the contribution of the low-energy secondary electrons to the induced chemistry. The effective cross-section related to dissociative secondary electron attachment at 6 eV is estimated to be 1 order of magnitude smaller. The 1 eV electrons do not induce significant chemical modification for a 2.5 mC cm â2 dose, excluding their contribution
Low-energy electron induced resonant loss of aromaticity: consequences on cross-linking in terphenylthiol SAMs
International audienceAromatic self-assembled monolayers (SAMs) can be used as negative tone electron resists in functional surface lithographic fabrication. A dense and resistant molecular network is obtained under electron irradiation through the formation of a cross-linked network. The elementary processes and possible mechanisms involved were investigated through the response of a model aromatic SAM, p-terphenylthiol SAM, to low-energy electron (0-10 eV) irradiation. Energy loss spectra as well as vibrational excitation functions were measured using High Resolution Electron Energy Loss Spectroscopy (HREELS). A resonant electron attachment process was identified around 6 eV through associated enhanced excitation probability of the CH stretching modes Μ(CH)(ph) at 378 meV. Electron irradiation at 6 eV was observed to induce a peak around 367 meV in the energy loss spectra, attributed to the formation of sp(3)-hybridized CHx groups within the SAM. This partial loss of aromaticity is interpreted to be the result of resonance formation, which relaxes by reorganization and/or CH bond dissociation mechanisms followed by radical chain reactions. These processes may also account for cross-linking induced by electron irradiation of aromatic SAMs in general
A combined DFT/HREELS study of the vibrational modes of terphenylthiol SAMs
Self-assembled monolayers of p-terphenylthiol (TPT, HS-(C6H4)2-C6H5) deposited onto gold can serve as model systems for
aromatic lithography resists. Such thin molecular films are suitably probed using high
resolution electron energy loss spectroscopy, due to its high surface sensitivity.
Extended energy loss spectra were measured at different probing energies. The TPT
monolayer overlapping Μ(CH) stretching modes could be modelled by a single
effective anharmonic oscillator sustained by a Morse potential energy curve, thanks to the
resonant excitation of the associated overtone series at 6Â eV. A remarkably good agreement
was obtained between the TPT monolayer energy loss spectrum and the computer-simulated
infrared vibrational spectrum of the isolated TPT molecule. Density Functional Theory
calculations for TPT, fully deuterated TPT and benzenethiol isolated molecules were
performed with the exchange correlation functional B3LYP and a dispersion correction,
using a triple ζ+ polarisation basis set. By comparing the vibrational patterns
obtained for these parent systems, (re-)assignments of all the features observed in the
TPT self-assembled monolayer energy loss spectrum are discussed. The obtained vibrational
assignments can be confidently transposed to other related systems, such as benzenethiol
and biphenyl self-assembled monolayers