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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Relationship between lower body strength and bone mineral density in postmenopausal women with long-term exercise training

Lee, Won-Jun January 2000 (has links)
The purpose of this study was (1) to compare the lower body strength, power, and the bone mineral density (BMD) of the proximal femur in a group of trained postmenopausal women who have been in low intensity exercise program for a long time with age-matched sedentary controls, and (2) to evaluate the magnitude of the correlation between muscle function and site-specific BMD in these postmenopausal women. Healthy postmenopausal women (n = 17) between the age of 60 and 80 were divided into two groups: 9 exercisers (mean ± SE, 74.8 ± 3.2 years) who had been in an exercise training program for at least 5 years and 8 control (mean ± SE, 71.6 ± 3.4 years) who had not been in any exercise program for at least 5 years. The exercise group performed three one hour sessions a week of aerobic and resistance training for an average of 9.9 years. The exercise training consisted of 30 minutes walking and one or two sets of twelve to fifteen repetitions focused on large muscle groups. The BMD of the proximal femoral region was assessed using dual-energy x-ray absorptiometry (DEXA). By using a Cybex Leg Press machine, 1-repetition maximum (1-RM) tests were performed for lower body strength and power of lower body were obtained by a seated chair rise. Statistical analysis demonstrated no statistical differences between the left and right region of the femur BMD for either group, with the averaged BMD being 0.858 g/cm2 for the controls and 0.853 g/cm2 for the exercisers. The trochanter BMD for the exercisers were 7 % (left) and 6 % (right) higher than the controls although these values were not statistically significant. The 1RM leg press strength ranged from 29.5 to 47.6 kg (mean ± SE, 40.21 ± 2.62 kg) in controls and from 31.8 to 61.2 kg (mean ± SE, 45.93 ± 3.72 kg) in exercisers. Although the exerciser group lifted 14.2 % more weight than the control group, the difference was not statistically significant. The results of power test ranged from 14.59 to 31.21 kg • m/sec (mean ± SE, 22.94 ± 5.67 kg • m/sec) in controls and from 13.63 to 38.60 (mean ± SE, 28.88 ± 6.81 kg • m/sec). The power did not differ significantly between the two groups. However, it is noted that between group differences approached significance at p < 0.07. Correlations between body composition and femoral neck BMD were also determined. Neither weight, nor BMI was significantly correlated with femoral neck BMD in the exercise and control group. Lower body strength and power did not correlate with the BMD of the femoral neck, Ward's triangle, or trochanter in either group. Although the BMD of the proximal femoral region did not differ between two groups the higher mean age (+ 3.2 years) of the exercise group suggested that a low intensity exercise training program can increase power and strength and maintain BMD in postmenopausal women. However, the low intensity of resistance training program utilized by the exercise group was no more effective in maintaining BMD than an active lifestyle. / School of Physical Education
2

Friction and adhesion mediated by supramolecular host–guest complexes

Guerra, Roberto, Benassi, Andrea, Vanossi, Andrea, Ma, Ming, Urbakh, Michael 13 January 2020 (has links)
The adhesive and frictional response of an AFM tip connected to a substrate through supramolecular host–guest complexes is investigated by dynamic Monte Carlo simulations. Here, the variation of the pull-off force with the unloading rate recently observed in experiments is unraveled by evidencing simultaneous (progressive) breaking of the bonds at fast (slow) rates. The model reveals the origin of the observed plateaus in the retraction force as a function of the tip-surface distance, showing that they result from the tip geometrical features. In lateral sliding, the model exhibits a wide range of dynamic behaviors ranging from smooth sliding to stick-slip at different velocities, with the average friction force determined by the characteristic formation/rupture rates of the complexes. In particular, it is shown that for some molecular complexes friction can become almost constant over a wide range of velocities. Also, we show the possibility of exploiting the ageing effect through slide-hold-slide experiments, in order to infer the characteristic formation rate. Finally, our model predicts a novel ‘‘antiageing’’ effect which is characterized by a decrease of the static friction force with the hold time. Such an effect is explained in terms of enhancement of adhesion during sliding, especially observed at high driving velocities.
3

Devenir des résidus médicamenteux et de leur métabolites au sein des Zones de Rejet Végétalisées (ZRV) / Evaluation of surface flow treatment wetlands as a polishing step for small communities wastewater treatment plants : evaluation and modeling of hydraulic behavior, fate of macropollutants and pharmaceuticals

Nuel, Maximilien 19 September 2017 (has links)
Les Stations de Traitement des Eaux Usées (STEU) sont l'une des principales sources de rejet de résidus médicamenteux dans l'environnement. Depuis 2009, les Zones de Rejet Végétalisées (ZRV) sont mises en oeuvre entre le rejet de la STEU et le milieu récepteur, mais leurs capacités d'abattement sont encore peu étudiées. Pour combler ce manque, les performances d'épuration de 2 STEU et de leur ZRV, ont été évaluées pendant 2 années. Les résidus médicamenteux (86) ont eu une majorité de rendements d'épuration compris entre 30 et 70 % dans les ZRV et avec des maximums en été et des minimums en hiver. Relativement aux abattements observés sur les STEU en amont, la contribution des ZRV à l'épuration globale du site était inférieure à 30 % du flux entrant. Aussi, la réduction des volumes d'eau rejetés au milieu naturel a été corrélée avec une augmentation des concentrations en résidus médicamenteux. Par ailleurs, les plantes ont montré une capacité d'absorption des médicaments spécifique à l'espèce étudiée, alors que l'observation des concentrations dans les boues, a mis en évidence une tendance à une adsorption en été et un relargage en hiver des micro-polluants. / Wastewater Treatment Plants (WWTP) are considered as one of the most important pharmaceutical compound discharges into the environment. Since 2009, French Water Agencies, promote Surface Flow Treatment Wetlands (SFTWs) at the outlet of WWTPs, between the WWTP and the receiving aquatic environment but their removal efficiencies are not well investigated. To overcome these lacks of knowledge, pollutant removal efficiencies of 2 WWTP and their SFTW were monitoring during 2 years. ln regard to pharmaceutical compounds (86), SFTW removal efficiency rates ranged from 30 to 70% with maximum values in summer and minimum values in winter. The SFTW removal efficiency contributions to WWTP were inferior to 30%. ln addition, SFTW inflow reductions were correlated with an increase of drug compound concentrations in the outflow. Furthermore, there was a specific absorption of these micro pollutants by plants whereas there were dynamic interactions between sampled mud and drugs residues with an adsorption during summer and a release during winter.
4

Optical Anisotropy and Molecular Orientation of CuPc Films and Optical Properties of Ultra-thin High-k Films

Ding, Li 15 October 2012 (has links) (PDF)
In the thesis CuPc thin films were investigated by (in situ) SE and RAS, which are employed to determine the out-of-plane and in-plane optical anisotropy and molecular orientation, respectively. CuPc is a promising candidate of organic semiconductors used in organic field effect transistors, organic light emitting diodes and organic solar cells. Vicinal Si(111) substrates are interesting due to the in-plane anisotropy caused by the steps and terraces on the surface. The strength of in-plane anisotropy of vicinal Si(111) is dependent on the offcut angle. The influence of offcut angle on out-of-plane and in-plane molecular orientation in CuPc thin films is explored. The in situ investigation of CuPc films suggests that structural changes occur during film growth. In addition, two different surface modification layers were utilized to examine the effect on CuPc molecular orientation: OTS monolayer with upright standing molecules and PTCDA layers with flat lying molecules. Metal-organic interface plays an important role in organic electronic devices. In-CuPc is chosen to be an example system investigated employing in situ SE and RAS. When In was thermally evaporated onto CuPc film, In atoms firstly diffuse into the CuPc film underneath and then aggregate to form clusters on top. Hafnium dioxide (HfO2) is currently a hot topic to replace the conventionally used SiO2 as gate dielectrics in order to minimize leakage current when further scaling down microelectronic devices. Since HfO2 films are often crystalline, in order to obtain amorphous films which are beneficial to minimize leakage current, aluminum oxide (Al2O3) (k value: 9) which stays amorphous at much higher temperatures are combined to overcome this difficulty. Two series of ultra-thin samples were deposited by atomic layer deposition: mixed layers HfxAl1-xOz and bilayers HfO2 on Al2O3. Optical constants and bandgap are determined using SE in the energy range of 0.7-10 eV. It is found that the (effective) optical bandgap of both mixed layer and bilayer structures can be tuned by the film composition. Aging effect of high-k films was observed after storage of samples in air for two months, which is attributed to further oxidation of the dielectric films caused by the oxygen diffusion from ambient air to high-k films. / In dieser Arbeit werden dünne Schichten aus Kupferphthalozyanin (CuPc) mittels spektroskopischer (in-situ) Ellipsometrie (SE) und (in-situ) Reflektions-Anisotropie-Spektroskopie (RAS) untersucht, um die optische Anisotropie in einer Ebene parallel und senkrecht zur Schichtoberfläche und die molekulare Orientierung zu bestimmen. CuPc ist ein aussichtsreicher Kandidat als organischer Halbleiter in organischen Feldeffekt-Transistoren, organischen Leuchtdioden und organischen Solarzellen. Vizinale Si(111)-Substrate sind wegen der Anisotropie in der Substratebene interessant, die durch die Treppen und Terrassen auf der Oberfläche verursacht wird. Die Stärke der Anisotropie der vizinalen Si(111)-Oberfläche ist vom Schnittwinkel (Offcut) abhängig. Es wird der Einfluss des Offcut-Winkels auf die molekulare Orientierung in dünnen CuPc-Schichten parallel und senkrecht zur Substratoberfläche untersucht. Die in-situ Untersuchungen von CuPc-Schichten weisen darauf hin, dass strukturelle Veränderungen beim Wachstum auftreten. Darüber hinaus wurden zwei unterschiedliche Oberflächenmodifizierungsschichten, um deren Wirkung auf die molekulare Orientierung von CuPc zu untersuchen, verwendet: eine OTS-Monoschicht mit aufrecht stehenden Molekülen und PTCDA-Schichten mit flach liegenden Molekülen. Metall-organische Grenzflächen spielen eine wichtige Rolle in organischen elektronischen Bauelementen. In-CuPc wird als Beispiel für ein Metall-organisches System durch in-situ SE und RAS untersucht. Wenn In thermisch auf eine CuPc-Schicht aufgedampft wird, diffundieren In-Atome zunächst in die darunterliegende CuPc-Schicht und bilden dann Cluster auf der Schicht. Hafniumdioxid (HfO2) ist ein heißer Kandidat für das Ersetzen des herkömmlich als Gate-Dielektrikum verwendeten SiO2 mit dem Ziel, die Leckströme bei der weiteren Verkleinerung mikroelektronischer Bauelemente zu minimieren. Um amorphe Schichten, die vorteilhaft zur Minimierung der Leckströme sind, zu erhalten, werden die HfO2-Schichten, die oft kristallin sind, mit Aluminiumoxid (Al2O3) (k-Wert: 9) kombiniert, das bei wesentlich höheren Temperaturen amorph bleibt. Zwei Serien von ultra-dünnen Proben wurden durch Atomlagenabscheidung hergestellt: Mischschichten HfxAl1-xOz und Doppelschichten HfO2 auf Al2O3. Die optischen Konstanten und Bandlücken wurden mittels SE im Energiebereich von 0,7 bis 10 eV bestimmt. Es hat sich gezeigt, dass die (effektive) Bandlücke der Misch- und Doppelschichten durch die Komposition abgestimmt werden kann. Nach Lagerung der High-k-Schichten für zwei Monate an Luft konnte ein Alterungseffekt beobachtet werden. Dieser wird auf die weitere Oxidation der dielektrischen Schichten, die durch Sauerstoffdiffusion aus der Umgebungsluft in die High-k-Schichten ermöglicht wird, zurückgeführt.
5

Optical Anisotropy and Molecular Orientation of CuPc Films and Optical Properties of Ultra-thin High-k Films: Optical Anisotropy and Molecular Orientation of CuPc Films and Optical Properties of Ultra-thin High-k Films

Ding, Li 25 September 2012 (has links)
In the thesis CuPc thin films were investigated by (in situ) SE and RAS, which are employed to determine the out-of-plane and in-plane optical anisotropy and molecular orientation, respectively. CuPc is a promising candidate of organic semiconductors used in organic field effect transistors, organic light emitting diodes and organic solar cells. Vicinal Si(111) substrates are interesting due to the in-plane anisotropy caused by the steps and terraces on the surface. The strength of in-plane anisotropy of vicinal Si(111) is dependent on the offcut angle. The influence of offcut angle on out-of-plane and in-plane molecular orientation in CuPc thin films is explored. The in situ investigation of CuPc films suggests that structural changes occur during film growth. In addition, two different surface modification layers were utilized to examine the effect on CuPc molecular orientation: OTS monolayer with upright standing molecules and PTCDA layers with flat lying molecules. Metal-organic interface plays an important role in organic electronic devices. In-CuPc is chosen to be an example system investigated employing in situ SE and RAS. When In was thermally evaporated onto CuPc film, In atoms firstly diffuse into the CuPc film underneath and then aggregate to form clusters on top. Hafnium dioxide (HfO2) is currently a hot topic to replace the conventionally used SiO2 as gate dielectrics in order to minimize leakage current when further scaling down microelectronic devices. Since HfO2 films are often crystalline, in order to obtain amorphous films which are beneficial to minimize leakage current, aluminum oxide (Al2O3) (k value: 9) which stays amorphous at much higher temperatures are combined to overcome this difficulty. Two series of ultra-thin samples were deposited by atomic layer deposition: mixed layers HfxAl1-xOz and bilayers HfO2 on Al2O3. Optical constants and bandgap are determined using SE in the energy range of 0.7-10 eV. It is found that the (effective) optical bandgap of both mixed layer and bilayer structures can be tuned by the film composition. Aging effect of high-k films was observed after storage of samples in air for two months, which is attributed to further oxidation of the dielectric films caused by the oxygen diffusion from ambient air to high-k films. / In dieser Arbeit werden dünne Schichten aus Kupferphthalozyanin (CuPc) mittels spektroskopischer (in-situ) Ellipsometrie (SE) und (in-situ) Reflektions-Anisotropie-Spektroskopie (RAS) untersucht, um die optische Anisotropie in einer Ebene parallel und senkrecht zur Schichtoberfläche und die molekulare Orientierung zu bestimmen. CuPc ist ein aussichtsreicher Kandidat als organischer Halbleiter in organischen Feldeffekt-Transistoren, organischen Leuchtdioden und organischen Solarzellen. Vizinale Si(111)-Substrate sind wegen der Anisotropie in der Substratebene interessant, die durch die Treppen und Terrassen auf der Oberfläche verursacht wird. Die Stärke der Anisotropie der vizinalen Si(111)-Oberfläche ist vom Schnittwinkel (Offcut) abhängig. Es wird der Einfluss des Offcut-Winkels auf die molekulare Orientierung in dünnen CuPc-Schichten parallel und senkrecht zur Substratoberfläche untersucht. Die in-situ Untersuchungen von CuPc-Schichten weisen darauf hin, dass strukturelle Veränderungen beim Wachstum auftreten. Darüber hinaus wurden zwei unterschiedliche Oberflächenmodifizierungsschichten, um deren Wirkung auf die molekulare Orientierung von CuPc zu untersuchen, verwendet: eine OTS-Monoschicht mit aufrecht stehenden Molekülen und PTCDA-Schichten mit flach liegenden Molekülen. Metall-organische Grenzflächen spielen eine wichtige Rolle in organischen elektronischen Bauelementen. In-CuPc wird als Beispiel für ein Metall-organisches System durch in-situ SE und RAS untersucht. Wenn In thermisch auf eine CuPc-Schicht aufgedampft wird, diffundieren In-Atome zunächst in die darunterliegende CuPc-Schicht und bilden dann Cluster auf der Schicht. Hafniumdioxid (HfO2) ist ein heißer Kandidat für das Ersetzen des herkömmlich als Gate-Dielektrikum verwendeten SiO2 mit dem Ziel, die Leckströme bei der weiteren Verkleinerung mikroelektronischer Bauelemente zu minimieren. Um amorphe Schichten, die vorteilhaft zur Minimierung der Leckströme sind, zu erhalten, werden die HfO2-Schichten, die oft kristallin sind, mit Aluminiumoxid (Al2O3) (k-Wert: 9) kombiniert, das bei wesentlich höheren Temperaturen amorph bleibt. Zwei Serien von ultra-dünnen Proben wurden durch Atomlagenabscheidung hergestellt: Mischschichten HfxAl1-xOz und Doppelschichten HfO2 auf Al2O3. Die optischen Konstanten und Bandlücken wurden mittels SE im Energiebereich von 0,7 bis 10 eV bestimmt. Es hat sich gezeigt, dass die (effektive) Bandlücke der Misch- und Doppelschichten durch die Komposition abgestimmt werden kann. Nach Lagerung der High-k-Schichten für zwei Monate an Luft konnte ein Alterungseffekt beobachtet werden. Dieser wird auf die weitere Oxidation der dielektrischen Schichten, die durch Sauerstoffdiffusion aus der Umgebungsluft in die High-k-Schichten ermöglicht wird, zurückgeführt.

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