Bottom Position (bottom + position)

Distribution by Scientific Domains


Selected Abstracts


Site-Selective Deposition of Metal Nanoparticles on Aligned WO3 Nanotrees for Super-Hydrophilic Thin Films

ADVANCED MATERIALS, Issue 13 2009
Masachika Shibuya
Highly aligned WO3 nanotrees are grown on metal tungsten by a simple hydrothermal reaction. Pd nanoparticles are selectively deposited on the WO3 nanotrees by a photocatalytic reduction reaction. Photocatalytic oxidation activity depends strongly on the position of the deposited Pd nanoparticles, and the WO3 nanotrees with Pd nanoparticles deposited at the bottom position exhibited efficient super-hydrophilicity. [source]


Interaction of atoms with graphenic-type surfaces for the chemistry of the interstellar medium: New properties of H dimers on the surface

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2010
D. Teillet-Billy
Abstract Following the works of Rougeau et al. (Chem Phys Lett 2006, 431,135) and Ferro et al. (Phys Rev B 2008, 78, 085417) on the one-sided double chemisorption of H atoms on graphenic platelets, we investigate the two-sided double chemisorption using DFT-GGA PW91 calculations. Equilibrium characteristics and potential energy curves for chemisorption are reported for the ortho, meta, para, and bottom positions. Contrary to the one-sided case, the two-sided ortho chemisorption, as well as the bottom position, is barrier-less, whereas the two-sided para chemisorption exhibits an activation barrier. The highest occupied Kohn-Sham orbital (HOKSO) of the H-graphene radical is shown to signal the privileged barrier-less double chemisorption sites. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]


Three-dimensional knee joint kinematics during golf swing and stationary cycling after total knee arthroplasty

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 12 2008
Satoshi Hamai
Abstract The expectation of returning to sports activities after total knee arthroplasty (TKA) has become more important to patients than ever. To our knowledge, no studies have been published evaluating the three-dimensional knee joint kinematics during sports activity after TKA. Continuous X-ray images of the golf swing and stationary cycling were taken using a large flat panel detector for four and eight post-arthroplasty knees, respectively. The implant flexion and axial rotation angles were determined using a radiographic-based, image-matching technique. Both the golf swing from the set-up position to the top of the backswing, and the stationary cycling from the top position of the crank to the bottom position of the crank, produced progressive axial rotational motions (p,=,0.73). However, the golf swing from the top of the backswing to the end of the follow-through produced significantly larger magnitudes of rotational motions in comparison to stationary cycling (p,<,0.01). Excessive internal,external rotations generated from the top of the backswing to the end of the follow-through could contribute to accelerated polyethylene wear. However, gradual rotational movements were consistently demonstrated during the stationary cycling. Therefore, stationary cycling is recommended rather than playing golf for patients following a TKA who wish to remain physically active. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source]


Comparison of LiDAR waveform processing methods for very shallow water bathymetry using Raman, near-infrared and green signals

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2010
Tristan Allouis
Abstract Airborne light detection and ranging (LiDAR) bathymetry appears to be a useful technology for bed topography mapping of non-navigable areas, offering high data density and a high acquisition rate. However, few studies have focused on continental waters, in particular, on very shallow waters (<2,m) where it is difficult to extract the surface and bottom positions that are typically mixed in the green LiDAR signal. This paper proposes two new processing methods for depth extraction based on the use of different LiDAR signals [green, near-infrared (NIR), Raman] of the SHOALS-1000T sensor. They have been tested on a very shallow coastal area (Golfe du Morbihan, France) as an analogy to very shallow rivers. The first method is based on a combination of mathematical and heuristic methods using the green and the NIR LiDAR signals to cross validate the information delivered by each signal. The second method extracts water depths from the Raman signal using statistical methods such as principal components analysis (PCA) and classification and regression tree (CART) analysis. The obtained results are then compared to the reference depths, and the performances of the different methods, as well as their advantages/disadvantages are evaluated. The green/NIR method supplies 42% more points compared to the operator process, with an equivalent mean error (,4·2,cm verusu ,4·5,cm) and a smaller standard deviation (25·3,cm verusu 33·5,cm). The Raman processing method provides very scattered results (standard deviation of 40·3,cm) with the lowest mean error (,3·1,cm) and 40% more points. The minimum detectable depth is also improved by the two presented methods, being around 1,m for the green/NIR approach and 0·5,m for the statistical approach, compared to 1·5,m for the data processed by the operator. Despite its ability to measure other parameters like water temperature, the Raman method needed a large amount of reference data to provide reliable depth measurements, as opposed to the green/NIR method. Copyright © 2010 John Wiley & Sons, Ltd. [source]


Spatial and temporal hotspots of termite-driven decomposition in the Serengeti

ECOGRAPHY, Issue 3 2010
Bernd P. Freymann
Ecosystem engineers are organisms that directly or indirectly control the availability of resources to other organisms by causing physical state changes in biotic or abiotic materials. Termites (Insecta, Isoptera) are among the most important ecosystem engineers in tropical ecosystems. We used a field experiment in the tall grasslands of Serengeti National Park, Tanzania, to investigate 1) the consumption by termites of grass litter and dung baits along the landscape gradient of catena position, and 2) seasonal variation in litter and dung removal. Our maps of termitaria and patterns of bait removal revealed clear spatial and temporal hotspots of termite activity. In the dry season termites removed more baits at the top-catena positions than at the bottom positions, but there was no effect of catena position in the wet season. Spatial hotspots of termite activity overlapped with those of both mammalian herbivores and predators. Within the framework of ecosystem engineering, this study suggests that intraspecific aspects of spatial heterogeneity and temporal variability deserve much greater consideration. [source]


Interaction of atoms with graphenic-type surfaces for the chemistry of the interstellar medium: New properties of H dimers on the surface

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2010
D. Teillet-Billy
Abstract Following the works of Rougeau et al. (Chem Phys Lett 2006, 431,135) and Ferro et al. (Phys Rev B 2008, 78, 085417) on the one-sided double chemisorption of H atoms on graphenic platelets, we investigate the two-sided double chemisorption using DFT-GGA PW91 calculations. Equilibrium characteristics and potential energy curves for chemisorption are reported for the ortho, meta, para, and bottom positions. Contrary to the one-sided case, the two-sided ortho chemisorption, as well as the bottom position, is barrier-less, whereas the two-sided para chemisorption exhibits an activation barrier. The highest occupied Kohn-Sham orbital (HOKSO) of the H-graphene radical is shown to signal the privileged barrier-less double chemisorption sites. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]