Development of colorization of grayscale images using CNN-SVM

Nowadays, there is a growing interest in colorizing many grayscales or black and white images dating back to before the colored camera for historical and aesthetic reasons. Image and video colorization can be applied to historical images, natural images, astronomical photography. This paper proposes a fully automated image colorization using a deep learning algorithm. First, the image dataset was selected for training and testing purposes. A convolutional neural network (CNN) was designed with several layers of convolutional and max pooling. Support Vector Machine (SVM) regression was used at the final stage. The proposed algorithm was implemented using Python with Keras and Tensorflow libraries in Google Colab. Results showed that the proposed system could predict the colored image from the training process's learning knowledge. A survey was then conducted to validate our findings

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Development of new high performance photoinitiating systems for the photopolymerization of monomers issued by oil industry and their applications in various modern technologies

L'étude de la thèse porte sur la conception de nouveaux systèmes photoinitiateurs performants afin d'initier la polymérisation radicalaire et la polymérisation cationique dans des conditions d'irradiation douces. En fait, différents systèmes de nature différente ont été étudiés : des composés organiques synthétisés comme photoinitiateurs, des co-initiateurs ou additifs, et des complexes de transfert de charge. De manière intéressante, les co-initiateurs ou additifs testés dans cette recherche sont considérés comme d'excellentes alternatives aux amines toxiques arornatiques, ouvrant la voie à des systèmes sans amine. L'idée de base de ce travail de thèse s'oriente vers l'introduction de diodes électroluminescentes (LED) comme sources d'irradiation inoffensives et économiques. En fait, c'est un grand défi de trouver de nouveaux photo-initiateurs capables de générer des espèces réactives en utilisant cette source d'irradiation de faible puissance. En outre, les objectifs de cette thèse vont du test de la capacité de photo-initiation des différents photo-initiateurs pour différents types de polymérisation lors de l'irradiation avec la LED à 405 nm en utilisant la spectroscopie infrarouge à transformée de Fourier en temps réel, à l'étude de leurs propriétés photophysiques, photochimiques et électrochimiques qui ouvrent la voie à la compréhension des interactions qui ont lieu dans les états excités conduisant aux mécanismes photochimiques, et enfin leurs applications dans diverses technologies modernes : La technologie d'impression 3D, la synthèse de photocornposites épais et remplis de verre libre avec une excellente profondeur de réticulation, la formation d'hydrogels. Dans ce sujet, des monomères issus de l'industrie pétrolière ont été utilisés.The PhD thesis study focuses on the design of new high-performance photoinitiating systems in order te initiate both the free radical polymerization an the cationic polymerization under mild irradiation conditions. In fact, different systems of different nature have been studied : synthesized organic compounds as photoinitiators, co-initiators or additives, and charge transfer complexes. Interestingly, the co-initiators or additives tested in this researcl are considered as excellent alternatives for aromatic toxic amines, paving the way for amine-free systems. The basic idea of this PhD work is moving towards the introduction of Light Emitting Diodes (LEDs) as unharmed and eeonomical sources of irradiation. As a malter of fact, it is a big challenge to find new photoinitiators able to generate reactive species using this low power irradiation source. In addition, the goals of this thesis range from testing the photoinitiating abilitiy of the different photoinitiators for different types of polymerization upon irradiation with the LED at 405 nm using real-time Fourier transform infrared spectroscopy, to study their photophysical, photochemical, and electrochemical properties which pave the way to understand the interactions that take place in the excited states leading to the photochemical mechanisms, and finally their applications in diverse modem technologies: 3D printing technology, synthesis of thick and filled glass fiber photocomposites with an excellent depth of cure, formation of hydrogels. In this topic, monomers issued by petroleum industry have been used

Supplemental Material, Qualitative_Article_-_Appendix - Switching costs impact on customer retention in telecommunication: An exploratory study in Lebanon

<p>Supplemental Material, Qualitative_Article_-_Appendix for Switching costs impact on customer retention in telecommunication: An exploratory study in Lebanon by Mira Thoumy, and Elie Abdallah in Competition and Regulation in Network Industries</p

Coumarins as Powerful Photosensitizers for the Cationic Polymerization of Epoxy-Silicones under Near-UV and Visible Light and Applications for 3D Printing Technology

International audienceIn this study, eight coumarins (coumarins 1-8) are proposed as near-UV and blue light sensitive photoinitiators/photosensitizers for the cationic polymerization (CP) of epoxysilicones when combined with 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate (IOD). Among these coumarins, four of them (coumarins 1, 2, 6 and 8) have never been reported in the literature, i.e., these structures have been specifically designed to act as photoinitiators for silicones upon near UV and visible irradiation. Good final reactive epoxy function conversions (FCs) and also high rates of polymerization (Rp) were achieved in the presence of the newly proposed coumarin-based systems. The polymers generated from the photopolymerization of epoxysilicones can be considered as attractive candidates for several applications such as: elastomers, coatings, adhesives, and so on. The goal of this study focuses also on the comparison of the new proposed coumarins with well-established photosensitizers i.e., 1-chloro-4-propoxythioxanthone (CPTX), 9,10-dibutoxyanthracene (DBA) or some commercial coumarins (Com. Coum). As example of their high performance, the new proposed coumarins were also used for laser write experiments upon irradiation with a laser diode at 405 nm in order to develop new cationic 3D printing systems

High performance dyes based on triphenylamine, cinnamaldehyde and indane-1,3-dione derivatives for blue light induced polymerization for 3D printing and photocomposites

International audienceIn this research, high performance dyes based on triphenylamine, cinnamaldehyde and indane-1,3-dione derivatives have been designed/synthesized and evaluated as photoinitiators for visible light photopolymerization. The introduction of light-emitting diodes (LEDs) as low-cost and secured sources of irradiation is one of the major purposes in this study, where a LED at 405 nm was used for both the cationic polymerization (CP) of thin epoxide samples and the free radical polymerization (FRP) of thin TMPTA films. The proposed dyes showed very high efficiencies in the presence of the two-component photoinitiating systems based on Dye/Iodonium salt (Iod) couples or Dye/Amine (such as N-Phenylglycine (NPG) or ethyl 4-(dimethylamino)benzoate (EDB)) couples for the FRP and/or CP, highlighting their importance through a photo-oxidation (with Iod) process but also through a photo-reduction (with amine) process. The examined dyes are also able to initiate the FRP of thin acrylate films in the presence of the three-component (Dye/Iod/NPG) systems where very high rates of polymerization (Rp) and great final reactive function conversions (FCs) were achieved. Objectives of this work concern the study of the photoinitiating abilities of the different photoinitiating systems using FTIR technique but also the 2 study of the chemical mechanisms which was mainly examined in solution. The use of the investigated systems for 3D printing experiments (using LED projector or laser diode @405 nm) is particularly outlined. Finally, the production of thick glass fiber photocomposites presenting excellent depth of cure is also accomplished in the presence of these dyes (using near-UV conveyor: LED@395 nm)

In-silico based development of photoinitiators for 3D printing and composites: Search on the coumarin scaffold

International audienceIn this work, the in-silico rational design of new photoinitiators by molecular modeling for specific wavelength (here 405 nm) and specific applications (3D printing, composites) is reported. A large number of (keto)coumarin derivatives were investigated by molecular modeling and their synthesis and more detailed photochemical investigations are based on obtaining structures having both excellent predicted light absorption properties @ 405 nm and high excited state energy levels (to ensure high photochemical reactivity). More particularly, four new families of coumarins were designed (4 of the 19 proposed coumarins were never synthesized (N2,M6,T1,T6)): the first family is based on Nitrocoumarins (N1-N6), the second one on Methoxybenzene-based coumarins and Ethoxycoumarins (M1-M6), the third one on Thiophene-based coumarins (T1-T6) and the last family studied concerns Alkyne-based coumarin (A1). The purpose of this work concerns the study of the photoinitiating ability of these compounds in different monomers for different polymerization processes (free radical, cationic) using FTIR technique. The different compounds reported in this work are very efficient to initiate the free radical polymerization of (meth)acrylates but also the cationic polymerization of epoxides upon mild irradiation conditions using a Light Emitting Diode (LED) at 405 nm as visible light source. Nitrocoumarins were identified as the best candidates for photoinitiation among the different families of coumarins investigated in this work. More precisely, nitrocoumarins are characterized by very good polymerization profiles, great final reactive function conversions (FC) and also high rates of polymerization (Rp). The electrochemical and pho-tochemical properties of the different compounds were also studied to get a deeper insight into the photo-chemical mechanisms supporting the initiation process. A full picture of the involved photochemical mechanisms is provided. Thanks to the astounding polymerization initiating ability of these coumarins, their use in 3D printing applications can be worthwhile. Remarkably, using these compounds, the preparation of photo-composites was possible even in difficult light penetration conditions resulting from the presence of fibers inside the resins

Coumarin Derivatives as Photoinitiators in Photo-oxidation and Photo-reduction Processes and Kinetic Model for Simulations of the Associated Polymerization Profiles

International audienceIn this work, the design of an original series of coumarin derivatives (CoumC1-CoumC13) is presented. Chemical structures of these coumarins were selected by molecular modelling to ensure both excellent light absorption properties and high potential photoreactivity (high excited state energy). As a striking result of this in-silico design, 8 of the 13 proposed coumarins were never presented and were specifically proposed for this work, evidencing the interest of the structures. New multi-component photoinitiating systems (PISs) based on these coumarins are proposed for the free radical polymerization (FRP) of (meth)acrylates and examined upon visible light irradiation using the light emitting diode (LED) as a safe and economical irradiation source. The proposed systems are based on coumarins which act as remarkable photoinitiators/photosensitizers (PIs/PSs) combined with N-phenylglycine (NPG) and/or iodonium salt (Iod) as co-initiators in order to generate the reactive species (radicals) that will initiate the photopolymerization recation. Investigation of the chemical mechanisms suggested by the different interactions that take place as well as the photophysical and photochemical properties of coumarins are provided. The access 2 to high polymerization rates (Rp), excellent photoinitiating abilities and great reactive function conversions (FC) is possible with these structures based on the coumarin core. Coumarins show high efficiency for the FRP of (meth)acrylates by reaction with iodonium salt (a photo-oxidation process) or with amine (a photo-reduction process). These compounds were used in 3D printing resins but also for the preparation of photocomposites. In this latter case, an excellent depth of cure was noted as remarkable behavior. To rationalize the experimental results, a kinetic model for a three-component system has been established to analyze the role of oxygen in the monomer conversions and the conversion enhancement observed while using an amine as a co-initiator

Boron Compounds as Additives for the Cationic Polymerization Using Coumarin Derivatives in Epoxy Silicones

International audienceThis work aims at using two borane derivatives, namely Borane A: B(C6F5)3 and Borate B: C32H12BF24Na as additives for the cationic polymerization of epoxy silicones under visible light, in the presence of coumarins as photosensitizers and 4‐isopropyl‐4′‐methyldiphenyl iodonium tetrakis(pentafluorophenyl)borate (SC939). The effect of boron compounds on the absorption and the emission spectra of a coumarin is particularly outlined. These two boron compounds can improve both the polymerization rate and the final monomer conversion. Moreover, the effect of adding water on the reactivity of the system is studied. It should be noted that the studied boron additives are able to enhance in an interesting way the polymerization rate when light irradiation is switched off through a dark polymerization (DP) mechanism. This latter behavior is highly desired for practical applications. Finally, the very high photoreactivity of boron compounds is employed for the development of new cationic 3D printing resins upon exposure to a light emitting diode (LED) projector at 405 nm, as well as for direct laser write experiments, by means of a laser diode at 405 nm. The 3D polymerization occurs through a cationic process which can be quite useful in order to reduce the shrinkage usually observed in radical polymerization