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131.
Elmoutaouakkil A Peyrin F Elkafi J Laval-Jeantet AM 《IEEE transactions on medical imaging》2002,21(4):354-362
The quantification of cancellous bone network from computed tomography (CT) images requires a segmentation step which is crucial and difficult because of the partial volume effect in CT images. In this paper, we present and evaluate a new approach for segmenting cancellous bone network from high-resolution CT (HRCT) slices. The idea is first to detect a skeleton from the crest lines of the structure and then to thicken it to extract the whole bone structure by satisfying local neighborhood constraints. The segmentation requires the adjustment of relative and not absolute parameters like most methods. We quantified the influence of these parameters on architectural measurements. Results were first validated by using a physical phantom and then examined on a series of 12 HRCT images of human lumbar vertebra of different ages. We demonstrated that the choice of segmentation parameters yielded important variability on architectural measurements (up to 20%), but less variability than a more commonly used approach. This stresses the importance of settle on the segmentation parameters for once, which is possible with the proposed method. 相似文献
132.
This paper reports on silicon nanowire growth on oxidized silicon substrates using different approaches for gold catalyst
deposition. The gold coated surfaces and the resulting nanowires were characterized using scanning electron microscopy. The
gold catalysts were made up of gold nanoparticles (50 nm diameter), which were either dispersed or spotted at different concentrations
using a robot, or were formed on a patterned Si/SiO2 substrate by metal evaporation (63 nm diameter). The subsequent silicon nanowire growth was accomplished by CVD decomposition
of silane gas (SiH4) at high temperature (400–500°C) in a vapor-liquid-solid (VLS) process. Under these conditions, a high density of silicon nanowires (SiNWs) was achieved
on the oxidized silicon surfaces, but the distribution of the nanowires was found to be inhomogeneous in the case of the gold
nanoparticles. Such result is attributed to the aggregation of the nanoparticles during the growth process. Alternatively,
when gold nanodot catalysts were lithographically patterned on the surface, the nanowires were obtained in the patterned regions. 相似文献
133.
R. Elleuch R. Salhi N. Maalej J.-L. Deschanvres R. Maalej 《Materials Science and Engineering: B》2013,178(17):1124-1129
Er doped ZnO thin films have been synthesized from zinc acetates dihydrate (C4H6O4Zn·2H2O) and Erbium tris (2,2,6,6-tetramethyl-3,5-heptadionate) (Er(TMHD)3) by aerosol assisted chemical vapor deposition AACVD atmospheric pressure technique. Films were deposited in the temperature range of [370–500 °C] on Si (1 1 1) substrate. Nano-disk shaped grains were grown on the top of the film surface. The morphology of the as-deposited films was found to be dependent on the substrate temperature. After annealing in air atmosphere, XRD patterns revealed a highly oriented c-axis Er:ZnO films with hexagonal wurtzite structure without any second phase. Under 488 nm excitation, the intra 4f–4f green emission (2H11/2, 4S3/2 → 4I15/2 transitions) gradually increased with increasing annealing temperature. Also, the local structure of Er changes to a pseudo-octahedral structure with C4v symmetry. The ZnO film with 2.504 at.% Er3+ doping has the best crystalline structure and the best resolved PL spectra. Using 325 nm excitation, all the samples showed an ultraviolet emission centered at 380 nm originating from a near band EDGE emission and a broad band green emission centered at 520 nm from deep levels. The optical response was correlated with crystallinity of the synthesized thin films. 相似文献
134.
H. Salhi K. Chafai H. Lassri M. Abid E. K. Hlil 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1735-1738
Magnetic properties of Ni/Ti multilayers, prepared by the DC triode sputtering method, have been studied by magnetic measurements. Both metal layers are crystalline with a (111) fiber structure when they are thicker than 20 Å. The magnetization decreases with a decrease in Ni layer thickness t Ni and the analysis of the results at 5 K indicates the presence of a dead Ni layer about 13 Å thick. The effective anisotropy K eff of Ni/Ti multilayers is obtained using a torque magnetometer. Spin-wave theory has been used to explain the temperature dependence of the magnetization. Approximate values for bulk exchange interaction J b, surface exchange interaction J S and interlayer coupling strength J I for various Ni layer thicknesses have been obtained. 相似文献
135.
Salhi A Rainò G Fortunato L Tasco V Martiradonna L Todaro MT De Giorgi M Cingolani R Passaseo A Luna E Trampert A De Vittorio M 《Nanotechnology》2008,19(27):275401
The authors have recently demonstrated the enhancement of the quantum dot laser modal gain, linearly scaling with the number of stacked QD layers. These results allowed the achievement of multi-quantum dot (MQD) lasers, the zero-dimensional counterpart of MQW lasers, with a modal gain as high as 42?cm(-1), in a seven-layer structure. A detailed investigation of the structural and optical properties was performed on laser structures with three, five and seven QD layers. Such an investigation clearly shows that the high uniformity of QD layer features is responsible for the linear increase of the modal gain and its high value. 相似文献
136.
Germain C Campigna E Salhi I Morisseau S Navarro-Teulon I Mach JP Pèlegrin A Robert B 《Protein engineering, design & selection : PEDS》2008,21(11):665-672
Natural killer (NK) cells are at the crossroad between innate and adaptive immunity and play a major role in cancer immunosurveillance. NK cell stimulation depends on a balance between inhibitory and activating receptors, such as the stimulatory lectin-like receptor NKG2D. To redirect NK cells against tumor cells, we designed bifunctional proteins able to specifically bind tumor cells and to induce their lysis by NK cells, after NKG2D engagement. To this aim, we used the 'knob into hole' heterodimerization strategy, in which 'knob' and 'hole' variants were generated by directed mutagenesis within the CH3 domain of human IgG1 Fc fragments fused to an anti-CEA or anti-HER2 scFv or to the H60 murine ligand of NKG2D, respectively. We demonstrated the capacity of the bifunctional proteins produced to specifically coat tumor cells surface with H60 ligand. Most importantly, we demonstrated that these bifunctional proteins were able to induce an NKG2D-dependent and antibody-specific tumor cell lysis by murine NK cells. Overall, the results show the possibility to redirect NK cytotoxicity to tumor cells by a new format of recombinant bispecific antibody, opening the way of potential NK cell-based cancer immunotherapies by specific activation of the NKG2D receptor at the tumor site. 相似文献
137.
Salhi A Barat D Romanini D Rouillard Y Ouvrard A Werner R Seufert J Koeth J Vicet A Garnache A 《Applied optics》2006,45(20):4957-4965
GaInAsSb/GaAlAsSb/GaSb distributed-feedback (DFB) laser diodes based on a type I active region were fabricated by molecular beam epitaxy at the Centre d'Electronique et de Micro-Optoélectronique de Montpellier (CEM2). The DFB processing was done by Nanoplus Nanosystems and Technologies GmbH. The devices work in the continuous-wave regime above room temperature around an emission wavelength of 2.3 microm with a side-mode suppression ratio greater than 25 dB and as great as 10 mW of output power. The laser devices are fully characterized in terms of optical and electrical properties. Their tuning properties made them adaptable to tunable diode laser absorption spectroscopy because they exhibit more than 220 GHz of continuous tuning by temperature or current. The direct absorption of CH4 is demonstrated to be possible with high spectral selectivity. 相似文献