342 research outputs found
Temperature-Triggered Sequential On-Surface Synthesis of One and Two Covalently Bonded Porous Organic Nanoarchitectures on Au(111)
No full textInternational audienceSubtle variations of surface temperature can drastically influence the on-surface synthesis of two-dimensional covalent graphene nanoarchitectures. The structure of the engineered nanoarchitectures not only results from the temperature-activation of the catalytic process, but it is also governed by the temperature-dependent geometry of intermolecular assembly. The sequential engineering of porous organic nanoarchitectures based on the covalent Ullmann coupling of star-shaped 1,3,5-tris(3,5-dibromophenyl)benzene molecules on Au(111) in vacuum is investigated using scanning tunneling microscopy and X-ray photoemission spectroscopy. This molecule can form one-covalent-bond or two-covalent-bonds with neighboring molecules. At room temperature, the molecules self-assemble into a porous halogen-bonded network stabilized by two types of X 3 synthons. One-covalent-bond dimers appear on the surface after annealing at 145 °C. One-covalent-bond chains are created after annealing at 170 °C. Most of the molecules are bonded to two neighbors. One-covalent-bond hexagons as well as two-covalent-bond dimers are appearing on the surface after annealing at 175 °C. Annealing at 275 °C leads to the formation of a porous 2D hexagonal two-covalent-bond nanoarchitecture. STM images show that the number of intermolecular covalent bonds as well as the number of covalently bonded molecular neighbors increases as the temperature rises. Core level spectroscopy shows that the molecules are fully dehalogenated after annealing at 260 °C. These observations show that dibromophenyl-based molecules are promising organic compounds to hierarchically and selectively engineer covalent porous graphene nanoarchitectures having different structures
Mathieu Jaboulay (1860-1913) and His Innovations in Vascular and General Surgery
No full textMathieu Jaboulay (1860-1913) was an inventor in vascular and general surgery. He fabricated many new surgical techniques and instruments such as Jaboulay method for vascular sutures, Jaboulay anastomotic button, and Jaboulay amputation, known also as hemipelvectomy. In addition, he was a pioneer in heterologous transplantation and sympathectomy. He found death suddenly in a terrible train crash. He was a reputable Professor of Surgery at Lyon Faculty of Medicine with prestigious students in vascular surgery. © The Author(s) 2019
X synthon geometries in two-dimensional halogen-bonded 1,3,5-tris(3,5-dibromophenyl)benzene self-assembled nanoarchitectures on Au(111)-(22 x )
No full textInternational audienceSelf-assembly of star-shaped 1,3,5-tris(3,5-dibromophenyl)benzene molecules on Au(111)-(22 x ) in a vacuum is investigated using scanning tunneling microscopy and core-level spectroscopy. Scanning tunneling microscopy shows that the molecules self-assemble into a hexagonal porous halogen-bonded nanoarchitecture. This structure is stabilized by X synthons composed of three type-II halogen-interactions (halogen-bonds). The molecules are oriented along the same direction in this arrangement. Domain boundaries are observed in the hcp region of the herringbone gold surface reconstruction. Molecules of the neighboring domains are rotated by 180°. The domain boundaries are stabilized by the formation of X synthons composed of two type-II and one type-I halogen-interactions between molecules of the neighboring domains. Core-level spectroscopy confirms the existence of two types of halogen-interactions in the organic layer. These observations show that the gold surface reconstructions can be exploited to modify the long-range supramolecular halogen-bonded self-assemblie
High resolution and time resolved photoemission spectroscopy for developing more efficient materials to reduce energy consumption and increase renewable energy production
No full textDue to the increase of energy consumption and the resulting ecological challenge, a collective awareness leads to the development of renewable energies and more efficient materials to increase the green energy production. Development of efficient photovoltaic materials is very closely related to their chemical and electronic properties. A better knowledge of these imbricated properties is needed, in addition to a better comprehension of their interplay with charge transport mechanisms. Exciton creation and recombination processes, charge transfer and charge collection processes take place at the surface and interface of the photoactive materials. Photoemission spectroscopy as chemical specific and surface sensitive spectroscopic technique is a method of choice on the study of physical phenomena at the origin of photoconversion efficiency. Time resolved photoemission spectroscopy has been recently renewed interest covering time scale from fs to more than seconds. It permits to probe the dynamics of relaxation of photoexcited charges and determine their lifetime. It finds application in various materials used in solar photovoltaics. In this paper, we define the physical and chemical properties determined by the combination of high resolution and time resolved photoemission spectroscopy. We show examples dealing with the development of renewable energy and energy consumption reduction in agreement with the current ecological trend for a better future
Mechanics of inhomogeneous turbulence and interfacial layers
No full textThe mechanics of inhomogeneous turbulence in and adjacent to interfacial layers bounding turbulent and non-turbulent regions are analysed. Different mechanisms are identified according to the straining by the turbulent eddies in relation to the strength of the mean shear adjacent to, or across, the interfacial layer. How the turbulence is initiated and the topology of the region of turbulence are also significant factors. Specifically the cases of a layer of turbulence bounded on one, or two, sides by a uniform and/or shearing flow, and a circular region of a rotating turbulent vortex are considered and discussed.
The entrainment processes at fluctuating interfaces occur both at the outer edges of turbulent shear layers, with and without free-stream turbulence (e.g. jets, wakes and boundary layers), at internal boundaries such as those at the outside of the non-turbulent core of swirling flows (e.g. the ‘eye-wall’ of a hurricane) or at the top of the viscous sublayer and roughness elements in turbulent boundary layers. Conditionally sampled data enables these concepts to be tested. These concepts lead to physically based estimates for critical modelling parameters such as eddy viscosity near interfaces, entrainment rates, maximum velocity and displacement heights
Synthetic data (Part 1) for "HOISDF: Constraining 3D Hand-Object Pose Estimation with Global Signed Distance Fields"
No full textHere we provide the data of our article "HOISDF: Constraining 3D Hand-Object Pose Estimation with Global Signed Distance Fields". It contains the preprocessed SDF samples. Meanwhile, we also include rendered data for HO3Dv2 here.
The overall structure of the data is:
├── render_sdf_ho3d.zip - Contains the processed SDF files for HO3Dv2 rendered images.
├── train_ho3d.zip - Contains the processed SDF files for HO3Dv2 training set.
├── full_test_dexycb.zip - Contains the processed SDF files for DexYCB full test set.
The code to reproduce the results is available at: https://github.com/amathislab/HOISDF
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If you find our code, weights, predictions or ideas useful, please cite:
@inproceedings{qi2024hoisdf, title={HOISDF: Constraining 3D Hand-Object Pose Estimation with Global Signed Distance Fields}, author={Qi, Haozhe and Zhao, Chen and Salzmann, Mathieu and Mathis, Alexander}, booktitle={Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition}, pages={10392--10402}, year={2024}}UPAMATHISLCAVSDSC-G
Symmetric group actions on the cohomology of configurations in R^d
No full textIn this paper we deal with the action of the symmetric group on the cohomology of the conguration space Cn(d) of n points in Rd. This topic has been studied by several authors and it is well-known that for d even H* (Cn(d);C) ≌ 2IndSnS21 while, for d odd, H* (Cn(d);C) ≌ CSn. On the cohomology algebra H* (Cn(d);C) there is, in addition to the natural Sn-action, an extended action of Sn+1; this was shown for the case when d is even by Mathieu, Robinson and Whitehouse and the second author using three dierent methods. For the case when d is odd it was shown by Mathieu (anyway we will give an elementary algebraic construction of the extended action for this case). The purpose of this article is to present some results that can be obtained, in an elementary way, exploiting the interplay between the extended action and the standard action. Among these we will recall a quick proof for the formula cited above for the case when d is even and show how to extend this proof to the case when d is odd. We will also show how to locate among the homogeneous components of the graded algebra H* (Cn(d);C) the copies of the standard, sign and standard tensor sign representations and we will give explicit formulas for both the extended and the canonical actions on the low-degree cohomology modules
Internal Structure of InP/ZnS Nanocrystals Unraveled by High-Resolution Soft X-ray Photoelectron Spectroscopy
No full textInternational audienc
β-Diketonato Complex Film on a Graphite Surface
No full textInternational audienceThe structural and magnetic properties of a drop-cast film of flat C54H34Br4CuO4, a β-diketonato complex functionalized with bromine atoms, on a graphite surface are investigated using scanning tunneling microscopy, synchrotron X-ray absorption spectroscopy, and X-ray magnetic circular dichroism. Experimental measurements reveal that the Cu-complexes preferentially lay flat on the graphite surface. The magnetic hysteresis loops show that the organic thin film remains paramagnetic at 2 K with an easy axis of magnetization perpendicular to the graphite surface and is therefore perpendicular to the plane of the Cu-complex skeleton
Simulating cement microstructural evolution during calcium leaching
No full textCalcium leaching is one of the important degradation mechanisms causing dissolution of the crystalline phases such as, AFm, portlandite increasing capillary porosity. Further it leads to decalcification of an amorphous C-S-H phase causing increase in the gel porosity and in turn degrading the long term performance of concrete structures. In this paper a lattice Boltzmann based pore-scale reactive transport approach in the context of simulating the evolution of microstructure of a hardened cement paste during calcium leaching is presented. This approach is based on fundamental principles of chemical thermodynamics and mass transport. The example presented illustrates influence of location of mineral grains and surface area on overall dissolution rate and pore structure evolution.Structural EngineeringCivil Engineering and Geoscience
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