Search results for "Tram"
showing 10 items of 1979 documents
A theoretical study on NHC-catalysed enantioselective cycloaddition of ketenes and 3-aroylcoumarins: mechanism and enantioselectivity.
2018
NHC-catalysed enantioselective cycloaddition of ketenes to 3-aroylcoumarins to yield dihydrocoumarin-fused dihydropyranones has been investigated using DFT methods at the B3LYP/6-31G* and MPWB1K/6-311G** computational levels. Two plausible mechanisms have been studied: the “ketene-first” mechanism A and the “coumarin-first” mechanism B. An analysis of the activation Gibbs free energies involved in the two competitive pathways makes it possible to rule out the pathway associated with the “coumarin-first” mechanism B. The first step of the “ketene-first” mechanism A is the formation of zwitterionic intermediate IN1-Zvia a nucleophilic attack of NHC 1 on ketene 2. A [4 + 2] cycloaddition throu…
Virtual prototyping of a new intramedullary nail for tibial fractures
2012
In this work a new distal interlocking system has been developed which is easy to use, allows a reduction of the operating time and consequently the exposure to radiations both for surgeon and patient. The main goal of this study has been the design of a new intramedullary nail for tibial fractures able to simplify and speed up the distal locking operation phases. After a preliminary stage during which several candidate concepts have been proposed and analysed, the best solution has been developed and deeply investigated. The new system, called “expansion nail”, has been firstly modelled by setting up a full parametric CAD model and, then, tested by running non linear FEM analyses to evalua…
Tramway Track: A New Approach for Measuring the Transverse Profile of Worn-Out Rails
2012
Abstract Monitoring the wear condition of the tramway superstructure is one of the key points to guarantee an adequate safety level of the light rail transport system. The purpose of this paper is to suggest a new non-conventionalprocedure for measuring the transverse profile of rails in operation by means of image-processing technique. This methodological approach is based on the “information” contained in high-resolution photographic images of tracks and on specific algorithms which allow to obtain the exact geometric profile of the rails and therefore to measure the state of the rail-head extrados wear.
Gold(I) Complexes Nuclearity in Constrained Ferrocenyl Diphosphines: Dramatic Effect in Gold‐Catalyzed Enyne Cycloisomerization
2020
International audience; Di-tert-butylated-bis(phosphino)ferrocene ligands bearing phosphino substituents R (R=phenyl, cyclohexyl, isopropyl, mesityl, or furyl) allow tuning the selective formation of Au(I) halide complexes. Thus, dinuclear linear twocoordinate, but also rare mononuclear trigonal three-coordinate and tetrahedral four-coordinate complexes were formed upon tuning of the conditions. Both Au(I) chloride and rarer Au(I) iodide complexes were synthesized, and their X-ray diffraction analysis are reported. The significance of the control of structure and nuclearity in Au(I) complexes is further illustrated herein by its strong effect on the efficiency and selectivity of gold-cataly…
Presurgical role of MRI tractography in a case of extensive cervicothoracic spinal ependymoma
2017
Background: Intramedullary spinal ependymoma is a tumor, hardly characterizable with conventional magnetic resonance (MR) imaging only. MR diffusion tensor imaging (DTI) with three dimensional fiber tracking reconstructions allows the evaluation of the relationship between neoplasm and white matter fiber tracts, being a powerful tool in presurgical planning. We present DTI findings in a case of a young female with an extensive cervicothoracic spinal ependymoma. Case Description: The patient complained of a 2 month history of acute urinary retention, weakness and numbness on the lower limbs and the upper left limb. She underwent MR imaging that showed an extensive cervicothoracic spinal mass…
Biografies de músics de jazz i índex alfabètic eixamplat dels jazzístes més significatius
2017
Continuació de l'arxiu: 'JAZZ-apropament pràctic al gènere jazzístic - Nau Gran - U.V',. Les biografies de músics de Jazz més significatives estàn ordenades alfabèticamente i la seua contextualizació resulta més pràctica. Continuation of the file: 'JAZZ-apropament pràctic al gènere jazzístic-Nau Gran-U. V ',. The biographies of the most significant Jazz musicians are alphabetically arranged and their contextualization is more practical.
The photophysics and photochemistry of cofacial free base and metallated bisporphyrins held together by covalent architectures
2007
Abstract This review focuses on the photophysical properties of bisporphyrin systems held in a face-to-face configuration by covalent bonds via flexible or rigid spacers and metal–metal bonds. The cofacial arrangement induces intramolecular bismacrocycle interactions promoting basic photophysical events such as excitonic interactions and energy and electron transfers. These events are relevant to mimic light harvesting and reactor devices known for photosynthesis in plants, and can be monitored by luminescence and flash photolysis methods.
Unveiling the Intramolecular Ionic Diels–Alder Reactions within Molecular Electron Density Theory
2021
The intramolecular ionic Diels–Alder (IIDA) reactions of two dieniminiums were studied within the Molecular Electron Density Theory (MEDT) at the ωB97XD/6-311G(d,p) computational level. Topological analysis of the electron localization function (ELF) of dieniminiums showed that their electronic structures can been seen as the sum of those of butadiene and ethaniminium. The superelectrophilic character of dieniminiums accounts for the high intramolecular global electron density transfer taking place from the diene framework to the iminium one at the transition state structures (TSs) of these IIDA reactions, which are classified as the forward electro density flux. The activation enthalpy ass…
The challenge of open tibial shaft fractures: When tomanage with external fixation and when to useintramedullary nailing?
2020
Treatment of open tibial shaft fractures is challenging. External fixation (EF) is comparatively safe in treating these open injuries with the main advantages of easy application, minimal additional disruption, and convenient subsequent soft tissue repair. Tibial intramedullary nailing (IM) is optimal for the treatment of open tibial fractures. This study aims to report the outcomes of our multi-center experience in the management of open tibial shaft fractures, evaluating the efficacy and safety of using either the external fixation (EF) or intramedullary nailing (IM).In this study, clinical-radiographic results were evaluated in 26 cases of open fractures treated with an external fixator …
A rare case of extra-intramedullary dorsal tanycitic ependymoma, radically removed with intraoperative neurophysiological monitoring
2015
Introduction: Tanycitic dorsal extra and intramedullary ependymoma is a rare form of tumor. From the histological point of view, these tumors show several aspects that make difficult the differential diagnosis from schwannomas and pilocytic astrocytomas. Tanycytic variant, often occurs in the thoracic tract of the spinal cord, and it is constituted by tanycites, that are typical elongated and bipolar cells that give to the tumor fibrillary aspects. Tanycitic variant has been recently characterized as a variant of ependymoma, since the 2000 World Health Organization (WHO) system. Case presentation: A 57 years old woman presented with intractable back pain often radiating to the left leg. Neu…