jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Songuigama Coulibaly
Source:  (preprint, 2018-01-11)
Field: Chemistry — Organic Chemistry

Synthesis and antituberculosis activity of some 1,10-phénanthrolinone derived La tuberculose est une infection humaine cosmopolite à transmission pulmonaire causée par Mycobactérium tuberculosis. Elle représente l'une des principales causes de mortalité dans le monde. La prise en charge thérapeutique de cette maladie est confrontée aujourd’hui à une forte pharmacorésistance des bacilles à la plupart des médicaments antituberculeux habituellement indiqués. Face à cette situation la recherche de nouvelles molécules plus efficaces échappant au phénomène de pharmacorésistance est encouragée par l'OMS. C'est dans ce contexte que nous avons conçu des dérivés de la 1,10-phénanthrolinone, analogues structuraux des quinolones connues pour leurs activités antituberculeuses. Ces dérivés ont été préparés par condensation de la 8-aminoquinoléine et de l'étoxyméthylènemalonate d'éthyle, suivit d'une cyclisation intramoléculaire pour conduire à la 1,10-phénanthrolinone-3-carboxylate d'éthyle. La modulation chimique de cette dernière a permis d'obtenir la plupart des dérivés de la 1,10-phénanthrolinone préparés. Les dérivés de la 1,10-phénanthrloninone synthétisés ont fait l'objet d'une évaluation de leurs activités antibacillaires. Parmi ceux-ci, certains dérivés 6-nitro-1,10-phénanthrolinones se sont particulièrement illustrés par leurs performances antibacillaires avec des CMI comprises entre 0,31 et 9,84 μM. Par ailleurs, cette activité est conservée sur les souches de mycobactéries sensibles et les souches résistantes aux quinolones ce qui fait penser à un probable mécanisme d'action différent. De plus, ces molécules se sont avérées non toxiques sur les cellules Vero avec des IC50> 100 μg/mL ( soit 16 à 64 fois leurs CMI). Notre approche pharmacochimique a conduit à l’élaboration de nouvelles molécules possédant une structure de type 1,10-phénantrolinone dont le profil chimique diffère de celui de toutes les classes chimiques d’antituberculeux existantes. Les résultats obtenus ouvrent de nouvelles voies d'investigations pour la recherche de nouveaux antituberculeux voire anti-infectieux en série chimique des 1,10-phénantrolinones. Chemistry ; Medicine ; Pharmacology ; Virology Synthesis of β-Lactam Compounds ; Synthesis and biological activity ; Inorganic and Organometallic Chemistry
Authors: Ahmed Doma | Elbadawy A. Kamoun | S. Abboudy | Sherine N. Khattab | Ali A. El‐Bardan | Mohamed Ahmed Belal
Source: Egyptian Journal of Chemistry (article, 2018-12-10)
Field: Materials Science — Polymers and Plastics

Influence of blend ratio on the electrical characteristics of vulcanized SBR/NBR blends compatibilized by Cis-polybutadiene rubber Blends composed of styrene butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) have been fabricated by melt-blending technique using two-roll mill blend machine. Cis-polybutadiene rubber (CBR) was used as a compatibilizer for enhancing the homogeneity between blend phases. No previous reports were found to discuss improving electrical properties of vulcanized SBR/NBR blends using unfilled rubber system (i.e. no fillers incorporation). SEM micrographs were utilized to verify the compatibility between two rubber ingredients in various blends, owing to the use of compatibilizer. Thermal stability of blends was investigated by differential thermal analysis (DTA) and differential scanning calorimetric (DSC) to evaluate the influence of blend ratio on the compatibility of investigated samples. Results revealed that the dielectric properties of blends are dramatically influenced by altering the blend ratio. The results revealed that the SEM observations confirmed the compatibilization effect of CBR on vulcanized SBR/NBR blends. Meanwhile, thermal properties of vulcanized SBR/NBR blends were enhanced with increasing of SBR contents in blends. The complex impedance graphs showed circular arcs showing the bulk contribution to overall electrical behavior for investigated vulcanized SBR/NBR blends. During I-V characteristics have been presented, where a remarkably change from linear behavior to nonlinear conduction at lower temperatures was found for 0SBR/100NBR blends. These findings supported and confirmed that the compatibilization effect and the blend ratio between rubber compositions have strongly influenced on their thermal and electrical properties of vulcanized blends. Vulcanization ; Polybutadiene ; Materials science ; Natural rubber ; Composite material ; Polymer blend ; Compatibilization ; Copolymer ; Polymer Polymer Nanocomposites and Properties ; Conducting polymers and applications ; Polymer crystallization and properties
Authors: Faith J. Scott
Source: Open Scholarship Institutional Repository (Washington University in St. Louis) (article, 2018-01-01)
Field: Chemistry — Spectroscopy

Instrumentation for Cryogenic Dynamic Nuclear Polarization and Electron Decoupling in Rotating Solids Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) using the higher polarization of electron radical spins compared to nuclear spins. The addition of electron radicals for DNP to the sample can cause hyperfine broadening, which decreases the resolution of the NMR resonances due to hyperfine interactions between electron and nuclear spins. Electron decoupling has been shown to attenuate the effects of hyperfine coupling in rotating solids. Magic angle spinning (MAS) DNP with electron decoupling requires a high electron Rabi frequency provided by a high-power microwave source such as a frequency-agile gyrotron. This dissertation describes the development of instrumentation to improve electron decoupling through a higher electron Rabi frequency, including two designs for frequency agile gyrotrons and a MAS rotor resonator to increase the effect of microwaves at the sample. Electron spin relaxation times are increased at cryogenic temperatures, enabling manipulation of electron spins with lower electron Rabi frequency. Therefore, a cryostat with interchangeable MAS-DNP NMR probes for DNP experiments ranging from 4-80 K has been constructed and tested. Decoupling (probability) ; Instrumentation (computer programming) ; Nuclear engineering ; Polarization (electrochemistry) ; Physics ; Nuclear physics ; Engineering ; Chemistry ; Computer science ; Control engineering Advanced NMR Techniques and Applications ; Crystallography and Radiation Phenomena ; Solid-state spectroscopy and crystallography
Authors: Géraldine Rapp
Source: theses.fr (ABES) (preprint, 2018-12-12)
Field: Materials Science — Polymers and Plastics

Multi-scale analysis of thermo-oxidative ageing on crosslinked polyethylene blends Les travaux entrepris dans le cadre de cette thèse portent sur l’étude de la représentativité du vieillissement thermique accéléré par rapport au vieillissement en conditions d’usage de mélanges de polyéthylènes utilisés comme isolant de câbles qualifiés K1 de dernière génération dans les bâtiments réacteurs des centrales nucléaires. L’influence de l’état physique des constituants du mélange pendant le vieillissement sur les cinétiques et les mécanismes de vieillissement est également étudiée. Le matériau est un mélange de deux polyéthylènes : un polyéthylène linéaire (PE) et un polyéthylène ramifié (PEcB) réticulé au peroxyde. Une approche basée sur l’analyse multi-échelle (moléculaire, microstructurale, macromoléculaire et macroscopique) a été mise en place. Plusieurs températures de vieillissement ont été choisies afin de faire varier l’état physique de l’un ou des deux polyéthylènes du mélange au cours du vieillissement. Les résultats à l’échelle moléculaire montrent les mêmes produits d’oxydation et les mêmes cinétiques pour le PE et le PEcB. En revanche, on observe une oxydation plus rapide du mélange 5050. Les cinétiques d’oxydation obéissent à une loi d’Arrhenius pour des vieillissements compris entre 80°C et 110°C, mais l’extrapolation à la température d’utilisation (60°C) n’est pas représentative du résultat expérimental. L’état physique (solide ou fondu) des échantillons au moment du vieillissement n’explique pas la non-représentativité des vieillissements accélérés. Les variations des propriétés mécaniques peuvent être reliées à l’évolution de la microstructure de chaque polymère et de leur architecture macromoléculaire au cours du vieillissement thermo-oxydant. Néanmoins, il apparaît difficile de corréler l’évolution de la structure chimique au cours du vieillissement avec l’évolution des propriétés mécaniques. Cette étude souligne l’importance de l’approche multi-échelle pour avoir une compréhension globale des phénomènes de vieillissement. Ageing ; Polyethylene ; Materials science ; Oxidative phosphorylation ; Scale (ratio) ; Composite material ; Polymer science ; Chemistry ; Medicine ; Biochemistry ; Geography ; Cartography Polymer crystallization and properties ; Microplastics and Plastic Pollution ; Polymer Nanocomposites and Properties
Authors: Y. Kemari | A. Mekhaldi | M. Teguar | G. Teyssèdre
Source: 2018 IEEE 2nd International Conference on Dielectrics (ICD) (article, 2018-07-01)
Field: Materials Science — Materials Chemistry

Unthresholded Recurrence Plots Analysis for Degradation Assessment of Power Cables Insulation Underground power cables have been widely used in transmission and distribution power systems, especially in urban areas. During their operating conditions, power cables are subjected to thermal, mechanical and electrical stresses. These stresses lead to accelerate the degradation process of the insulation material. In this paper, we present a novel methodology in the field that could be used to detect degradation level of power cables insulation due to thermal aging. In light of this, cross-linked polyethylene (XLPE) and polyvinyl chloride based compound (PVC, class B or PVC/B) were chosen as the studied materials. Thermal aging tests were performed at different aging temperatures (80, 100, 120 and 140 °C). Thereafter, the alternative bulk current through the aged samples was recorded at different aging stages and under AC applied voltage of 12 kV. For the aim to better analyze in-depth the obtained current waveforms, unthresholded recurrence plots (UTRPs) technique is introduced in order to extract features from the AC bulk current and reveal its characteristics. The obtained results show that the proposed method could be used as an assessment tool for current analysis and thermal degradation monitoring of insulation materials used in extruded power cables. Materials science ; Degradation (telecommunications) ; Cross-linked polyethylene ; Polyethylene ; Polyvinyl chloride ; Accelerated aging ; Composite material ; Voltage ; Thermal ; Power cable ; Current (fluid) ; Electrical engineering ; Forensic engineering ; Engineering High voltage insulation and dielectric phenomena ; Thermal Analysis in Power Transmission ; Electrical Fault Detection and Protection
Authors: Nikolaj V. Bekrenev | Dmitriy Yu. Lukov
Source: Herald of Dagestan State Technical University Technical Sciences (article, 2018-03-19)
Field: Materials Science — General Materials Science

ENERGY EFFICIENT DESALINATOR Objectives The aim of the research was the development of an ultrasonic generator of technological design with a wide frequency range of output voltage. Methods The prototype works were performed and the functional scheme of the multifrequency ultrasonic generator realised in the experimental sample was developed, as well as the design of an ultrasonic piezoceramic system capable of operating at two resonant frequencies of 22 and 44 kHz. Results Based on the feature analysis of the modern composite material structure and technologies for moulding products, it was found to be expedient to introduce ultrasonic impregnation into the technological process, which can ensure increased uniformity in filling the structure with a binder as well as greater homogeneity of physicomechanical characteristics. A schema for the ultrasonic generator built into the technological equipment is developed, providing the formation of harmonic signals with a frequency alternating from 20 to 60 kHz, and power adjustable from 100 to 500 W, which will allow the implementation of highperformance ultrasonic technologies for processing materials with a heterogeneous structure formed during the manufacturing process. The studies were carried out according to parametric optimisation of the converter taking into account the specific load types. A special feature of the generator's power supply is its versatility in terms of frequency and voltage ranges, as well as the required quality indicators of the energy generated. The generator allows the reference frequency to be programmed using a laptop and then fine-tuned from the control panel in resonance with the radiator with a resolution of 10 Hz directly. The built-in microprocessor allows the reference frequency entered from the laptop to be stored in the memory. Conclusion The use of multifrequency ultrasonic sources allows the acting parameters to be optimised for ultrasonic impregnation of fibre-reinforced composite materials as well as their finishing dimensional processing, depending on the density of the structure and the reinforcement scheme used. Ultrasonic sensor ; Diesel generator ; Voltage ; Computer science ; Electronic engineering ; Acoustics ; Engineering ; Electrical engineering ; Automotive engineering ; Diesel fuel Material Properties and Applications ; Engineering Technology and Methodologies ; Industrial Engineering and Technologies
Authors: Gustavo Galleani
Source:  (article, 2018-01-01)
Field: Materials Science — Ceramics and Composites

Development of glass optical fibers based on fluoride-phosphate for deep-UV optical transmission Submitted by GUSTAVO GALLEANI null (gugalleani@yahoo.com.br) on 2017-11-28T14:58:54Z&#13;\nNo. of bitstreams: 1&#13;\nTese doutorado - Gustavo Galleani - Unesp.pdf: 13704296 bytes, checksum: f0f5cf5c73b3f5a15b1072694cd63d1e (MD5) Fluoride ; Phosphate ; Transmission (telecommunications) ; Optical fiber ; Materials science ; Optoelectronics ; Optics ; Chemistry ; Computer science ; Telecommunications ; Inorganic chemistry ; Physics Glass properties and applications ; Advanced Fiber Optic Sensors ; Advanced Optical Network Technologies
Authors: Dalgıç, Ali Deniz | Atila, Deniz Hazal | Koman, Ezgi | Karataş, Ayten | Tezcaner, Ayşen | Keskin, Dilek
Source: OpenMETU (Middle East Technical University) (article, 2018-12-15)
Field: Materials Science — Polymers and Plastics

Diatom silika kabuk katkılı PHBV/PCL-pullulan taşıyıcıların kemik doku mühendisliğine uygunluğunun araştırılması Cell ; Bone marrow ; Fibrodysplasia ossificans progressiva Polymer Nanocomposites and Properties ; Polymer composites and self-healing ; Tribology and Wear Analysis
Authors: S Zh Ayzhambayeva | D O Tyskenova | Maxim Vedyashkin
Source: IOP Conference Series Materials Science and Engineering (article, 2018-12-19)
Field: Materials Science — Materials Chemistry

Investigation of vibration impact on metrological characteristics of measuring devices in conditions of pump station № channel named after Satpayeva The article presents the results of the investigation of the effect of vibration on the metrological characteristics of measuring instruments, measurement methods and measurement techniques in real operating conditions. The topicality of the work is to ensure the reliability of the measurement results of the pump unit operation parameters in order to achieve the uninterrupted operation of the pump station objects. The investigation was carried out using the method 102-1, a vibration test was performed under the influence of sinusoidal vibration. The tests were carried out by smoothly changing the frequency in the specified range from lowest to highest. The conducted vibration studies made it possible to establish when the "normal" vibration becomes a "problem" or exceeds the permissible levels, the results obtained helped to determine the source and cause of the vibration, thereby ensuring effective prevention and eliminating the malfunctions of pumping units. In addition, it is established that when vibration occurs at several frequencies, it separates one frequency from the other so that it is possible to obtain each individual vibration characteristic. It is suggested at the pumping station to check the measuring instruments for vibration resistance, which allows to determine whether there are any additional errors of the instrument under the influence of vibrations during measurement, for example, as a result of tearing off the measuring tips of the CMM touch sensor from the measured surface. In the course of the study, we found that the use of vibration damping with the use of liquids for manometric equipment is quite effective in the conditions of operation of the pumping station. It is established that the most effective method is vibrodempfirovanie, which consists in reducing vibration by strengthening the design of friction processes that dissipate vibrational energy. This can be achieved by immersing the pressure gauge in the liquid, reducing the vibration amplitudes even in the resonance zone will depend on the damping ratio of the oscillations n.. Vibration ; Metrology ; Reliability (semiconductor) ; Tearing ; Acoustics ; Engineering ; Channel (broadcasting) ; Measuring instrument ; Mechanical engineering ; Electrical engineering ; Power (physics) ; Physics ; Optics Advanced Materials and Semiconductor Technologies ; Sensor Technology and Measurement Systems ; Advanced Sensor Technologies Research
Authors: Universiti Sains Malaysia, Malaysia
Source: Journal of Engineering and Science Research (article, 2018-06-20)
Field: Materials Science — Materials Chemistry

Effect of Alumina and Halloysite clay on Electrical tree growth in Silicone Rubber Nanocomposite Nowadays Silicone Rubber (SiR) is recommended in high voltage cable accessories fabrication as it offers excellent electrical and mechanical properties. Electrical tree is one of the phenomenon which contributes to the main factor of SiR insulation breakdown. Recently, a new approach has been applied in order to enhance the insulation strength properties by introducing nano filler in undoped material. Thus, this paper presents the influence of nano-alumina and halloysite nanoclay on electrical tree growth in SiR at 0, 1 vol%, 2 vol% and 3 vol% concentration. The electrical tree growth was investigated at 8kVrms after tree inception voltage (TIV) within 30 minutes under room temperature. The results show reductions of electrical tree growth speed and accumulate damage (%) up to 2 vol% nano-alumina and up to 3 vol% halloysite nanoclay. Nevertheless the presence of 3 vol% nano-alumina in SiR leads to the faster electrical tree growth rate and the worst accumulate damage within 1 minute of electrical tree growth process. Halloysite ; Silicone rubber ; Materials science ; Composite material ; Nanocomposite ; Silicone ; Tree (set theory) ; Nano- ; Voltage ; Electrical engineering ; Mathematics ; Engineering High voltage insulation and dielectric phenomena ; Lightning and Electromagnetic Phenomena ; Power Transformer Diagnostics and Insulation
Authors: Magalie Delecluse
Source: SPIRE - Sciences Po Institutional REpository (article, 2018-12-04)
Field: Chemistry — Organic Chemistry

Synthèses d’hémicryptophanes pour la reconnaissance et la catalyse d’oxydation du méthane The synthesis of molecular receptors is fast-growing. The encapsulation of numerous substrates, thanks to the cavity of the host, appears interesting for a variety of domains: in biology, for the encapsulation of active principles; in ecology, for the imprisonment of toxic compounds; in physic, for the information storage… Including a catalytic site in these receptors enable them to mimic the activity of enzyme, which allow or accelerate chemical reactions in our organism in recognizing selectively a substrate and in reducing the activation energy, thanks to get closer the substrate and its catalyst. The hemicryptophanes are part of these new synthetic receptors. Composed of cyclotriveratrylene moiety linked to another symmetry C3 unit, they have already proved their efficiency in the molecular recognition and in catalysis. During this thesis, the aim was to develop new host, from their synthesis to their different applications as molecular containers of different substrates such as anions, cations, ion-pairs, zwitterions or small neutral molecules like methane. Finally, new catalysts were synthesized to the oxidation of alkanes in including different catalytic sites in the ligand developed during these three years of thesis. Chemistry Supramolecular Chemistry and Complexes
Authors: Yasmine Baloul
Source: theses.fr (ABES) (preprint, 2018-01-30)
Field: Chemistry — Analytical Chemistry

Contribution to the study of pharmaceutical residues treatment in aqueous solution by non-thermal plasmas. Application to paracetamol and esomeprazole De nombreuses molécules médicamenteuses ne sont pas traitées efficacement par les techniques classiques utilisées dans les stations d'épuration et s’accumulent dans les milieux naturels. L’objectif de cette thèse a été de développer un procédé d’oxydation avancée utilisant un plasma non thermique généré par décharge électrique pour le traitement de molécules médicamenteuses et d’identifier le schéma de dégradation d’une des molécules d’étude, à savoir le paracétamol. Les traitements ont été réalisés à l’aide de deux réacteurs : un réacteur multi-pointes avec le plasma au contact direct du liquide à traiter et un réacteur fil-cylindre avec le plasma en amont du liquide à traiter. Des taux de conversion supérieurs à 80% ont pu être obtenus avec des rendements énergétiques, qui peuvent atteindre 8g/kWh et 39 g/kWh pour le paracétamol et l’ésoméprazole, respectivement. La décharge électrique créée entre une pointe et le liquide a été caractérisée par la spectroscopie d’émission optique afin d’observer la présence des espèces oxydantes produites par le plasma et d’estimer la température du milieu faiblement ionisé. Les espèces produites dans le liquide lors de la dégradation du paracétamol et de l’ésoméprazole qui ont été identifiées par la technique HRMS, entre autres, sont principalement des acides carboxyliques ainsi que des produits azotés. L’identification des voies de production pour la formation des principaux produits ont été étudiés particulièrement à l’aide de nombreuses méthodes chimiques comme HPLC/MS, MS/MS, et de différents marquages de paracétamol. Il a été prouvé que les principaux acides carboxyliques produits proviennent de la rupture du cycle aromatique. En conclusion, cette étude nous a permis d’obtenir des rendements énergétiques de traitement des deux molécules d’étude comparables à ceux retrouvés en littérature, et surtout d’établir un chemin de dégradation du paracétamol. Esomeprazole ; Aqueous solution ; Plasma ; Chemistry ; Materials science ; Physics ; Medicine ; Organic chemistry ; Internal medicine ; Nuclear physics Analytical Methods in Pharmaceuticals ; Inhalation and Respiratory Drug Delivery