jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Daniel Micheroni
Source: Knowledge@UChicago (University of Chicago) (article, 2019-01-01)
Field: Chemistry — Inorganic Chemistry

Metal-Organic Frameworks for Energy Applications This dissertation presents the photochemical (Chapter 2), electrochemical (Chapters 3, 5), and photophysical (Chapter 4) properties of light harvesting and catalytic molecules incorporated into metal-organic frameworks (MOFs). Chapter 1 presents an overview of the goals, purposes, and background materials for the subsequent chapters. Chapter 2 reports cobalt-porphyrin moieties incorporated into two MOF architectures and their catalytic activities for photochemical hydrogen production in an aqueous media. By inserting zinc and cobalt ions into the porphyrin centers to serve as the photosensitizer and catalyst respectively, MOFs capable of hydrogen generation were developed within a single material without the need of a separate co-catalyst. The resulting assemblies give TONs as high as 75 after five hours irradiation in an acidic medium through a putative Co(III)-H intermediate, outperforming their homogenous counterparts by up to 15 times. Chapter 3 presents electrocatalytic proton reduction with Hf12-porphyrin MOFs covalently tethered to carbon nanotubes (CNTs). Covalent attachment of the MOF nanoplates to conductive CNTs improves electron transfer from the electrode to the Co-porphyrin active sites, leading to effective proton reduction. The Hf12-CoDBP/CNT assembly afforded a turnover number of 32,000 in 30 minutes with an average turnover frequency of 17.7 s-1, placing it among the most active Co-based molecular catalysts. Chapter 4 describes the photophysical and photochemical properties of a [Ru(bpy)2(py)2]2+ complex confined within a zinc-oxalate MOF (Ru@MOF). The MOF perfectly encapsulates [Ru(bpy)2(py)2]2+ complexes, thereby altering their vibrational and electronic states through sterics and by removing the effects of solvents. As a result, the photoluminescence lifetime and quantum yield of the material significantly increase, likely through the destabilization the dd-state. The photochemical stability of [Ru(bpy)2(py)2]2+ in Ru@MOF also significantly increases due to the shutdown of photosubstitution processes. This stability can be leveraged into further studies including transient absorption and photocrystallography among other spectroscopic techniques. Chapter 5 describes the incorporation of a precious metal free cobalt-terpyridine catalyst into two-dimensional metal organic layers (MOLs) for hydrogen production in acidic media. The Co-TPY MOL effectively stabilizes ultrasmall cobalt nanoparticles for hydrogen production with TOFs as high as 4300 hr-1 in pH=1 at a low overpotential of 715 mV. Metal-organic framework ; Environmental science ; Computer science ; Chemistry ; Adsorption Metal-Organic Frameworks: Synthesis and Applications
Authors: Ruth Hwang
Source: eScholarship (California Digital Library) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

A Study to Investigate the Efficacy of Ethylenediamine Tetra-(Methylene Phosphonic Acid) as a Coating Material to Reduce the Toxicity of Upconversion Nanoparticles in Liver Cell Lines Rare earth metals possess unique properties that make them extremely valuable for various industrial applications. Recently, there is a surge in the development of rare earth based upconversion nanoparticles (UCNPs) for biomedical applications including bioimaging and photothermal cancer therapy. Our findings on rare earth oxide nanoparticle biotransformation in an acidic environment and cytotoxicity raises safety concerns for rare earth based UCNPs. Although the health impacts of UCNPs have been carried out, they are mostly for lung effects after inhalation exposure and there are only limited studies on the effects of UCNPs on the liver. The liver is an important organ for nanotoxicological research because it is the primary bioaccumulation site for both incidental nanomaterials undergoing extrapulmonary translocation after inhalation and theranostic nanoparticles that are intravenously injected. This study aims to investigate the biotransformation pathways and mechanisms of toxicity of UCNPs to liver cells and determine whether ethylenediamine tetra-(methylene phosphonic acid) (EDTMP) is a suitable protective coating material to prevent liver cell toxicity. Understanding this aspect is important for the development of safe UCNPs for biomedical applications. Liver cell viability was assessed after exposure to coated and non-coated UCNPs. The EDTMP coating material was effective in reducing the toxicity of certain UCNPs based on the dose and chemical composition, suggesting it could be a safer-by-design approach for UCNP biomedical applications. Toxicity ; Chemistry ; Nanotoxicology ; Ethylenediamine ; Nanoparticle ; Cytotoxicity ; Biotransformation ; Nanotechnology ; Materials science ; Biochemistry ; Organic chemistry ; In vitro Lanthanide and Transition Metal Complexes ; Boron Compounds in Chemistry ; Innovative Microfluidic and Catalytic Techniques Innovation
Authors: Wei Wang
Source: theses.fr (ABES) (preprint, 2019-12-06)
Field: Materials Science — Materials Chemistry

Carbon based materials for electrochemical and chemical energy conversion and storage Energy conversion and storage have always been the two critical issues for human society. In this thesis, we focus on the development of sustainable carbon materials for effective electrochemical energy storage, especially for supercapacitors, and supported nickel catalysts for chemical energy conversion and storage, mainly on CO2 methanation. Two different biomass derived carbon structures, i.e. hierarchical carbon foam and graphene-like carbon nanosheets, have been synthesized and applied for supercapacitor. Exceptional electrochemical performances have been obtained. Meanwhile, nickel decorated macroscopic shape catalyst (Ni/OCF) has been developed for CO2 methanation with enhanced catalytic performance powered by electromagnetic induction heating (IH). The rapid energy regulation capability of IH system to jugulate the problem of temperature runaway has also been investigated in the last part using powdered alumina supported nickel catalyst for this exothermic reaction. Supercapacitor ; Methanation ; Exothermic reaction ; Materials science ; Catalysis ; Nickel ; Energy storage ; Electrochemistry ; Carbon fibers ; Graphene ; Chemical engineering ; Electrochemical energy conversion ; Chemical energy ; Nanotechnology ; Metallurgy ; Chemistry ; Organic chemistry ; Composite material ; Engineering ; Electrode ; Composite number ; Thermodynamics Catalytic Processes in Materials Science ; Catalysts for Methane Reforming
Authors: Zakaria Mahhouti
Source: SPIRE - Sciences Po Institutional REpository (preprint, 2019-12-19)
Field: Materials Science — Materials Chemistry

Synthèse et caractérisation de nanoparticules de ferrite de cobalt fonctionnelles et monodispersées Dans le présent travail, les nanoparticules monodispersées à base de ferrite de cobalt ont été explorées pour leurs propriétés magnétiques et leur effet magnétostrictif, ainsi que pour une utilisation en tant que ferrofluide. Les nanoparticules ont été dispersées avec succès dans un solvant organique. La chimie de surface de la nanoparticule magnétique s'avère cruciale pour obtenir une dispersion haute densité homogène et bien séparée dans l'hexane. De plus, l'acide oléique a été utilisé pour modifier la surface des nanoparticules de ferrite de cobalt et permettre d'obtenir une bonne dispersion. Les nanoparticules obtenues sont caractérisées par XRD, spectroscopie Raman, TGA, FT-IR, DLS, SEM et la caractérisation magnétique. En utilisant l'analyse STEM, nous avons constaté que la taille et la forme des nanoparticules pouvaient être contrôlées en faisant varier certains paramètres tels que la température de synthèse, la quantité et la nature des réactifs. En outre, des membranes anodiques poreuses à pores très ordonnés ont été fabriquées avec succès avec une anodisation en plusieurs étapes. Des nanorods de ferrite de cobalt ont été produites par la transformation des nanoparticules de CoFe2O4 à l'aide d'une membrane d’alumine poreuses. L'insertion des nanoparticules de CoF2O4 dans les pores des membranes a été étudiée par le microscope électronique à balayage, et il a été possible de suivre le comportement des nanoparticules de CoFe2O4 dans les pores lors de l'insertion ainsi que lors de la transformation Chemistry ; Polymer chemistry ; Nuclear chemistry Magnetic Properties and Synthesis of Ferrites
Authors: T. L. Ajeesha | Ashwini Anantharaman | Mary George
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Enhanced magnetic and catalytic properties of copper substituted barium M-hexagonal ferrites synthesized from chemical co-precipitation method Department of Chemistry, Stella Maris College, Chennai-600 086, India <em>E-mail</em>: maryge@gmail.com <em>Manuscript received online 30 August 2018, accepted 10 October 2018</em> Discharge of organic chemicals in to the water bodies leads problems to both human and aquatic life. Barium hexaferrite is an effective catalyst in the rapid degradation of methylene blue dye. In this regard, the present study was focused on synthesis of copper substituted barium photocatalyst by co-precipitation method and the as-synthesized materials were calcined at 650ºC for 8 h to form the corresponding ferrites. The obtained ferrites were characterized by UV-DRS, Fourier Transform Infrared (FT-IR), Powder X-ray Diffraction (PXRD), Transmission Electron Microscope (TEM), Vibrating Sample Magnetometer (VSM), Brunauer-Emmett-Teller (BET) techniques to study their structural, optical and magnetic properties respectively. The results indicate the substitution of copper in barium ferrite nanomaterials strongly influences the crystal structure and magnetic properties of the synthesized nanomaterial. Hexagonal crystal system ; Copper ; Barium ; Catalysis ; Coprecipitation ; Materials science ; Precipitation ; Chemical engineering ; Inorganic chemistry ; Metallurgy ; Crystallography ; Chemistry ; Organic chemistry ; Physics Magnetic Properties and Synthesis of Ferrites ; Electromagnetic wave absorption materials
Authors: Moussa Diawara
Source: theses.fr (ABES) (preprint, 2019-11-12)
Field: Materials Science — Materials Chemistry

DFT modeling of the catalytic properties of ceria used as interface materials in Solid Oxide Fuel Cells (SOFC) Le développement de nouveaux matériaux pour les piles à combustible à oxyde solide (SOFCs) est un challenge afin de répondre aux enjeux actuels: abaissement de la température de fonctionnement, utilisation de métaux non précieux, flexibilité d’utilisation du carburant ou encore résistance à la dégradation. A ces fins, une double approche théorique et expérimentale est développée depuis de nombreuses années au sein de l’équipe I2E, afin de mettre au point des matériaux à base de Cérine dopée en tant que matériaux d’interface permettant d’améliorer les propriétés catalytiques des anodes des SOFC. L’approche expérimentale a été mise en œuvre pour synthétiser des nanoparticules d’oxyde de cérium pure (baguette, cube ou octaèdre) exposant respectivement les surfaces (110), (100) et (111). Les résultats obtenus ont montré que l’orientation (100) était la plus réactive, suivie de la (110), puis de la (111) la moins réactive. Sur la base de ces résultats expérimentaux, cette thèse vise à développer une approche DFT pour étudier la première étape de l’activation de l’hydrogène sur une surface pure de CeO2, à savoir pour chaque orientation cristallographique, l’adsorption de la molécule sur la surface puis sa dissociation pour former des groupes hydroxyles : géométrie et énergie d’adsorption des états moléculaires et dissociés, chemin réactionnel conduisant de l’adsorption à la dissociation et les énergies d’activation correspondantes. Ensuite des calculs seront effectués pour évaluer l’effet d’une série de dopants (yttrium, gadolinium, samarium) sur le mécanisme de l’activation de l’hydrogène et les énergies d’activation correspondantes Mots clés : SOFC, Cérine, hydrogène, DFT. Catalysis ; Materials science ; Fuel cells ; Oxide ; Solid oxide fuel cell ; Interface (matter) ; Chemical engineering ; Complex oxide ; Chemistry ; Metallurgy ; Engineering ; Physical chemistry ; Composite material ; Organic chemistry Advancements in Solid Oxide Fuel Cells ; Catalytic Processes in Materials Science ; Fuel Cells and Related Materials
Authors: Małgorzata Olek | Witold Żukowski | Jerzy Baron
Source: Ecological Chemistry and Engineering S (article, 2019-03-01)
Field: Materials Science — Materials Chemistry

Sorption of Hydrogen Chloridein The Fluidized Bed Reactor Abstract Combustion of fuels, including renewable fuels and thermal treatment of waste (CFCs, pesticides), is associated with emissions of pollutants including halogens. The reversible process of sorption/desorption of HCl, in a fluidized (bubbling) bed reactor (BFB), during co-combustion of Cl-materials, was carried out. The thermal decomposition of methylene chloride (DCM, CH 2 Cl 2 ) in an inert sand bed with the addition of the hydroxyapatite sorbent (HAp, Ca 5 (PO 4 ) 3 (OH)) was investigated. The process parameters were as follows: temperature - 930 °C, the air excess - 1.3, stream rate of CH 2 Cl 2 - 50 cm 3 /h. The concentration of HCl, CCl 4 , CHCl 3 , CH 2 Cl 2 , CH 3 Cl, COCl 2 in the exhaust gases were monitored online with FTIR spectroscopy. The main chlorine product was hydrogen chloride. Samples of unprocessed HAp, taken from the bed during the process, and solid apatite residues were analyzed by X-ray diffraction (XRD). The content of chlorapatite (Ca 5 (PO 4 ) 3 Cl) in the analyzed samples was respectively 11, 53 and 19 %. X-ray fluorescence (XRF) analysis showed the molar ratio of Ca:P:Cl was: 1.00:0.36:0.01, 1.00:0.36:0.09, 1.00:0.37:0.04 respectively. The HAp could be used as an sorbent of the HCl (g) during combustion of materials containing chlorine. Sorption ; Sorbent ; Hydrogen chloride ; Chemistry ; Chlorine ; Nuclear chemistry ; Combustion ; Chloride ; Fluidized bed ; Inorganic chemistry ; Adsorption ; Organic chemistry Thermal and Kinetic Analysis ; Toxic Organic Pollutants Impact ; Thermochemical Biomass Conversion Processes
Authors: Kostiv | O Dzeryn | Yu Malynovskyi | V Farina | J Reeves | C Senanayake | P Monnier-Benoit | I Jabin | J.-N Jaubert | P Netchitailo | B Goyau | N Anisimov | A Kuzhae Va | G Berkova | V Berestovitskaya | // Russ | I Polyuzhin | N Vytrykush | G Marshalok | S Polevaya | M Fedevich | O Marshalok | S Karpyak | N Fedevich | M | L Gast | E Bell | H Teeter | J Song | B | J Smets | P Steenwinckel | N Anisimova | A Kuzhaeva | V Berestov Itskaya | I Kostiv | J Yatchyshyn | I Polevaya | N Karpyak | I Pyrig | I Polyova | H Marshalok
Source: Voprosy Khimii i Khimicheskoi Tekhnologii (article, 2019-06-26)
Field: Chemistry — Spectroscopy

Determination of optimal conditions for preparation of 2-hydroxyethyl-1,3,4-trimethylcyclohex-3-encarboxylate 2-Hydroxyethyl-1,3,4-trimethylcyclohex-3-encarboxylate (HTMC) was synthesized by the reaction of Diels-Alder. The influence of temperature and molar ratio of reagents on the yield of the end product was investigated. The kinetics of the cycloaddition reaction between 2,3-dimethylbuta-1,3-diene (DMB) and 2-hydroxyethylmethacrylate (HEMA) was studied. The reaction rate constants and the activation parameters of the reaction were determined. It was stated that the yield of HTMC increases from 76% to 87% when the temperature increases from 403 K to 433 K, respectively. With a further increase in the temperature, DMB boils and HEMA remains in a liquid state, therefore, the yield of the end product does not increase appreciably. An increase in the excess of DMB:HEMA from 1:1 to 2.5:1 allows increasing the yield of HTMC from 83% to 87%. The optimal conditions for the HTMC production have been determined as follows: the temperature of 433 K and the molar ratio of reagents DMB:HEMA=1.5:1; the yield of HTMC reaches 87% at the output of 104 g/(lh) under these conditions. On the basis of the obtained reaction rate constants and the activation parameters of the [4+2]-cyclic addition of 2,3-dimethylbuta-1,3-diene and 2-hydroxyethylmethacrylate, we found out that the reaction under study obeys the second-order kinetic equation. The kinetic data indicated the synchronous cyclization process. The acceleration of the reaction with an increase in the depth of the process can be explained by matrix or cellular effects. Chromatography ; Chemistry Analytical Chemistry and Chromatography ; Chemical Synthesis and Analysis ; Enzyme Catalysis and Immobilization
Authors: Eric Aimé Poutougnigni
Source: theses.fr (ABES) (preprint, 2019-12-19)
Field: Materials Science — Polymers and Plastics

Impact of photo-ageing on macromolecular architecture : use of fluorescent probes L’objectif de ce travail est de proposer une nouvelle méthodologie basée sur l’utilisation des sondes fluorescentes pour caractériser l'impact du photovieillissement sur l'architecture macromoléculaire des matériaux polymères. Des sondes fluorescentes telles que le Prodan® et le pyrène, sensibles à des changements de polarité, ou le naphtalène présentant une fluorescence d’excimère ont été imprégnées dans des films de polymères avant et après photooxydation. La polarité et sa modification dans les matrices d’EPDM, de XLPE (PE réticulé) et de PKHJ® a pu être caractérisée. Une modification de l’intensité et un déplacement de la longueur d’onde au maximum d’émission du Prodan® a permis de caractériser la formation de photoproduits d’oxydation polaires dans les polymères. La fluorescence d’excimère du naphtalène dans un EPDM réticulé ou photooxydé a permis de caractériser la modification de l’architecture macromoléculaire au cours du vieillissement. Cette technique montre un seuil de détection plus faible que celui de la thermoporosimétrie couramment utilisée pour la caractérisation des réseaux denses. Cette technique utilisant une sonde fluorescente se révèle être très complémentaire des techniques classique dites de solubilité (fraction de gel, gonflement…). Ageing ; Fluorescence ; Architecture ; Macromolecule ; Nanotechnology ; Chemistry ; Materials science ; Biology ; Art ; Physics ; Optics ; Biochemistry ; Visual arts Polymer crystallization and properties ; Advanced Polymer Synthesis and Characterization ; Dyeing and Modifying Textile Fibers
Authors: Mostafa Eesaee
Source: Espace École de technologie supérieure (École de technologie supérieure) (article, 2019-02-21)
Field: Materials Science — Materials Chemistry

Clay-containing polyolefin blends and nanocomposites for high voltage applications This thesis presents attempts made to prepare novel insulating materials based on polyolefin tuned through blending and nanotechnology for high voltage applications, mainly the insulating materials in high voltage power cables. An organically modified natural clay, montmorillonite, was used in different loadings as the nanoreinforcement to be dispersed in low-density polyethylene (LDPE) and polypropylene (PP). Furthermore, polystyrene-bpoly(ethylene-co-butylene)-b-polystyrene (SEBS) triblock copolymer was used as the secondary polymer to form an immiscible blend with the polyolefin to selectively accommodate and disperse the nanofiller.&#13;\n&#13;\nA high degree of dispersion of clay platelets was observed when clay was incorporated into either LDPE or PP. Clay incorporation has led to a solid-like rheological behavior with a shoulder in storage modulus in low frequencies. The neat blends of polyolefin with SEBS were observed to have a co-continuous morphology. The addition of clay to those blends resulted in a decrease of the dispersed domains.&#13;\n&#13;\nDielectric spectra of nanocomposites clearly showed two main relaxation processes representing Maxwell-Wagner-Sillars (MWS) interfacial polarization process at low frequency and dipolar relaxation at high frequency. A new relaxation peak was observed for blend nanocomposites that was hypothesized to be related to the elastomer phase. The 3D network of clay in nanocomposites facilitates the charge carriers flow when subjected to high electric fields resulting in a higher DC conductivity comparing to polyolefin homopolymers. This was shown to enable the nanocomposites to prevent the accumulation of space charge by persistently allowing the temporary stored charges to flow across the material. However, at elevated temperatures the current flow exceeds a threshold above which high amount of charges are injected and as a result the electric field is heavily distorted. All nanocomposites showed significant improvement in the AC breakdown strength comparing to the neat polyolefin. The intercalated/exfoliated clay layers create a tortuous path for charge carriers to flow and thus distribute the electric stress and prolong the breakdown time. However, LDPE nanocomposites showed diminished DC breakdown strength most probably due to the thermal instability brought by clay. Polyolefin ; Materials science ; Composite material ; Nanocomposite ; Low-density polyethylene ; Polypropylene ; Polystyrene ; Polyethylene ; Polymer blend ; Montmorillonite ; Polymer ; Copolymer High voltage insulation and dielectric phenomena ; Polymer Nanocomposites and Properties ; Dielectric materials and actuators
Authors: Mirjana Anđelković-Lukić
Source: Vojnotehnicki glasnik (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Energetic additives in explosive charges of rockets used during the war against the FR Yugoslavia in 1999 The use of explosive devices containing energy enhancement additives such as halogen compositions, metals in a form of fine powders and waxes resulted in the formation of toxic gases after their detonation. The released harmful gases together with the products of destruction of bombed targets had the effects of special chemical warfare. Explosive material ; Detonation ; Halogen ; Wax ; Chemical warfare ; Chemistry ; Materials science ; Organic chemistry ; Law ; Political science High-Velocity Impact and Material Behavior ; Nuclear Issues and Defense ; Energetic Materials and Combustion
Authors: Racha Abed Ali Abdine
Source: theses.fr (ABES) (preprint, 2019-12-02)
Field: Chemistry — Inorganic Chemistry

C-C and C-heteroatom bonds formation by copper catalyst or via ruthenium complexes Ruthenium ; Heteroatom ; Copper ; Catalysis ; Chemistry ; Polymer chemistry ; Combinatorial chemistry ; Organic chemistry ; Ring (chemistry) Asymmetric Hydrogenation and Catalysis ; Organometallic Complex Synthesis and Catalysis ; Chemical Synthesis and Analysis