Computing the Local Aromaticity of Benzenoids Thanks to Constraint Programming

International audienceBenzenoids are a subfamily of hydrocarbons (molecules that are only made of hydrogen and carbon atoms) whose carbon atoms form hexagons. These molecules are widely studied in theoretical chemistry. Then, there is a lot of problems relative to this subject, like the benzenoid generation or the enumeration of all its Kekulé structures (i.e. all valid configurations of double bonds). In this context, the computation of the local aromaticity of a given benzenoid is an important problematic since the aromaticity cannot be measured. Nowadays, computing aromaticity requires quantum chemistry calculations that are too expensive to be used on medium to large-sized molecules. But, there exist some methods related to graph theory which can allow us to compute it. In this article, we describe how constraint programming can be useful in order to compute the aromaticity of benzenoids. Moreover we show that our method is much faster than the reference one, namely NICS

Evaluation of choroidal tumors with optical coherence tomography: Enhanced depth imaging and OCT-angiography features

AimTo describe the vascular features of choroidal tumors using enhanced depth imaging (EDI), optical coherence tomography (OCT), and OCT-angiography.MethodsIn this prospective study, we evaluated 116 Caucasian patients with choroidal tumors (60 eyes with choroidal nevi, 40 with choroidal melanoma, 6 with choroidal hemangioma, 2 with optic disc melanocytoma, 6 with choroidal osteoma, and 2 with retinal metastases). Patients underwent a complete ophthalmic examination including bulbar echography, EDI-OCT, OCT-angiography, and multicolor imaging. Sixteen patients also underwent fluorescein and indocyanine angiography.ResultsThe left eye was more involved than the right eye. The mean tumor thickness was 1.23±0.17 mm in the 60 eyes with choroidal nevi; 2.75±0.83 mm in the 40 eyes with choroidal melanoma; 3.28±0.78 mm in the 6 eyes with retinal angioma; 2.02±0.001 mm in the 2 eyes with optic disc melanocytoma; 2.40±0.31 mm in the 6 eyes with choroidal osteoma; and last, 3.49±0.001 mm in the 2 eyes with retinal metastases. OCT-angiography showed: (i) a lack of blood flow in the outer retinal layer (ORL) and a normal choroid capillary layer in choroidal nevi and optic disc melanocytomas; (ii) a lack of blood flow in the ORL of choroidal metastases; and (iii) a dense irregular vascular network in the ORL and choroid capillary layers of choroidal melanomas, choroidal hemangiomas, and choroidal osteomas.ConclusionsOCT-angiography is a noninvasive reliable method with which to evaluate the vascularization of small choroidal tumors and may improve the diagnosis of these tumor

Flip Distances Between Graph Orientations

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