jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Kimberly M. Steward
Source: Carolina Digital Repository (University of North Carolina at Chapel Hill) (article, 2019-08-12)
Field: Chemistry — Organic Chemistry

Strategies for the Synthesis and Use of β-Stereogenic α-Keto Esters I. Extant Methods for the Preparation of α-Keto Esters An overview of the synthetic methods to prepare α-keto esters is presented, with a particular focus on strategies to incorporate a stereocenter at the β-position. II.Catalytic Nucleophilic Glyoxylation of Aldehydes The synthesis of β-silyloxy α-keto esters via a cyanide catalyzed benzoin-type reaction with silyl glyoxylates and aldehydes is described. Critical to the success of the reaction was identifying Yb(OiPr)?3? and acetone cyanohydrin as a mild source of cyanide to prevent isomerization of the products to the corresponding α-silyloxy β-keto esters. Several secondary transformations add to the utility to the α-keto ester products. Of the methods available to prepare β-hydroxy α-keto acid derivatives, this method provides the most direct route and displays the broadest substrate scope. III.Asymmetric Synthesis of α-Keto Esters via Cu(II)-Catalyzed Aerobic Deacylation of Acetoacetate Alkylation Products A simple and efficient method for the preparation of β-stereogenic α-keto esters is described using a copper(II)-catalyzed aerobic deacylation of substituted acetoacetate esters. The substrates for the title process arise from catalytic, enantioselective conjugate addition and alkylation reactions of acetoacetate esters. The mild conditions do not induce racemization of the incipient enolizable α-keto ester. The reaction is tolerant of a number esters, certain ketones, ketals and nitro groups and establishes synthetic equivalency between acetoacetate esters and the glyoxylate anion synthon. IV.Dynamic Kinetic Resolution of α-Keto Esters via Asymmetric Transfer Hydrogenation The development of the first highly selective dynamic kinetic resolution of β-stereogenic α-keto esters via asymmetric transfer hydrogenation using a newly designed (arene)Ru(monosulfonamide) catalyst is described. For substrates incorporating a diester at the γ-postion, spontaneous lactonization of the nascent α-hydroxyl group onto the pendant ester occurs to provide trisubstituted γ-butyrolactones with complete diastereocontrol. Extension of this method to β-substituted α,δ-diketo esters results in chemoselective dynamic reduction of the α-keto ester providing highly enriched δ-keto α-hydroxy esters. Stereocenter ; Chemistry ; Organic chemistry ; Enantioselective synthesis ; Catalysis Asymmetric Synthesis and Catalysis ; Synthetic Organic Chemistry Methods ; Cyclopropane Reaction Mechanisms
Authors: Ananth Kandala | K. Srinivasu
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2019-07-01)
Field: Materials Science — Materials Chemistry

First principles investigation of atomic gold dispersed g-C3 N4 as an active catalyst for CO oxidation reaction School of Physics, University of Hyderabad, Hyderabad-500 046, India Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai-400 085, India Homi Bhabha National Institute, Mumbai-400 094, India <em>E-mail</em>: ksvasu@barc.gov.in <em>Manuscript received online 15 May 2019, revised and accepted 01 June 2019</em> Density functional theory calculations have been performed to explore atomic Au decorated graphitic carbon nitride (Au@g-C<sub>3</sub> N<sub>4</sub> ) as an active catalyst for CO oxidation reaction. Binding energy of Au atom to the carbon nitride substrate is found to be sufficiently strong to prevent the aggregation of adsorbed metal atoms to form clusters. Binding energy of both the reactants over Au@g-C<sub>3</sub> N<sub>4</sub> is significantly higher as compared to that of the product. CO oxidation over Au@g-C<sub>3</sub> N<sub>4 </sub>is demonstrated to follow the Langmuir-Hinshelwood (LH) mechanism initially and then through the Eley-Rideal (ER) mechanism. Minimum energy path for both the LH and ER steps has been investigated through nudge elastic band and dimer methods. Highest energy barrier for first CO<sub>2</sub> formation through LH step is calculated to be 44.19 kJ/mol whereas the second CO<sub>2</sub> formation by ER step is found to be almost barrier less. Strong interaction between the reactants and catalyst surface is attributed to the observed charge transfer from metal <em>d</em> states to the 𝝅* states of reactants. Catalysis ; Chemical engineering ; Materials science ; Nanotechnology ; Chemistry ; Organic chemistry ; Engineering Catalytic Processes in Materials Science ; Catalysis and Oxidation Reactions ; Mesoporous Materials and Catalysis
Authors: Benjamin Hoelzel
Source: SHAREOK (University of Oklahoma; Oklahoma State University; Central Oklahoma University) (article, 2019-05-10)
Field: Chemistry — Organic Chemistry

Additive Manufacturing of HDPE Using Selective Laser Sintering Selective Laser Sintering (SLS) is an additive manufacturing technique that bonds solid powder particles into complex 3-Dimensional (3D) shapes. These objects are constructed by repeatedly sintering or fusing layers of powder onto a build plate until the completed part is developed. Through the aid of an open source computer software known as Repetier Host, the desired component is sliced into many cross-sectional layers that are pathed out by a laser. Each new layer is created by new powder being deposited onto the previous layers and again a laser tracing out the cross-sectional path defined by Repetier Host. This technique has become more popular of recent as SLS allows for superior mechanical properties of printed components as well as the lack of required support material due to the excess powder around the print. On the other hand, High Density Polyethylene (HDPE) is a type of thermoplastic that has a high strength to density ratio and can be developed into complex components using SLS. As such, this thesis investigates and reports on the production and characterization of HDPE samples using SLS. The SLS machine used in this thesis was modified from an online design to allow both an affordable way to run experiments with HDPE powder and to truly understand the parameters and specifications needed to print HDPE powder into complex geometries. After running various test prints with HDPE, it was concluded that the most influential factors of successfully printing HDPE involve the ambient chamber temperature around the print, the temperature of the build plate, the laser intensity, the laser scanning speed, and the thickness of each layer. These five factors are crucial for keeping the temperature of the entire sample uniform and inside the sintering window, eliminating the natural tendency of HDPE samples to warp and deform during the printing process. Results show that these influences also directly impact the geometry accuracy, density, and mechanical properties of the printed samples. Finally, the characterization results from the printed HDPE samples were compared to characterization results of casted samples at similar densities and geometries. Selective laser sintering ; High-density polyethylene ; Sintering ; Materials science ; Selective laser melting ; Business ; Composite material ; Polyethylene ; Microstructure Photopolymerization techniques and applications ; Additive Manufacturing and 3D Printing Technologies
Authors: А. А. Филиппов
Source: EPJ Web of Conferences (article, 2019-01-01)
Field: Materials Science — General Materials Science

Features of the experimental determination of the elastic characteristics of epoxy resin with the addition of silicon dioxide nanoparticles Current work describes experimental determination Young modulus of polymer composition based on epoxy resin filled two types of silicon dioxide nanoparticles with different average diameter. It is shown, that each type of powder differently increases the Young's modulus of the epoxy resin for constant concentration. For Tarkosil powders, the increase in Young's modulus for filled epoxy was from 7 to 25% with a decrease in the average particle diameter from 48 to 18 nm. The change in the Young's modulus of the polymer is significantly less with the addition of Aerosil powders. Young's modulus increased from 0 to 15% with diameters from 12 to 8 nm. Epoxy ; Modulus ; Materials science ; Composite material ; Polymer ; Silicon dioxide ; Young's modulus ; Silicon ; Nanoparticle ; Elastic modulus ; Bulk modulus ; Particle (ecology) ; Nanotechnology ; Metallurgy Material Properties and Applications ; Polymer Science and Applications ; Tribology and Wear Analysis
Authors: Ebenezer Adelowo
Source: Florida International University Digital Commons (Florida International University) (article, 2019-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Lithium-Ion Hybrid Capacitor Devices: Towards High-Performance Electrochemical Capacitive Energy Storage Hybridization of lithium-ion batteries (LIBs) and electrochemical capacitors (ECs) at electrode level can potentially provide high-performance capacitive energy storage having a good combination of high energy density, high power density, and moderate cycling longevity. Lithium-ion hybrid capacitor (LIHC) system consisting of a battery-type anode and a capacitor-type cathode represents an attractive hybridization approach aimed at bridging the performance gap between the two energy storage systems. The application of such energy storage system may extend the functionalities of many electronic devices. In this dissertation, different LIHC configurations were designed and evaluated. An LIHC device comprising electrostatically sprayed reduced graphene oxide (rGO)-based material as both electrodes were fabricated and studied in organic liquid electrolyte media. Both electrochemical and direct lithium contact pre-lithiation approaches were explored to achieve high electrochemical performance. Moreover, in contrast to the widely used battery-type anode, an LIHC with battery-type cathode and rGO-based anode was assembled and evaluated. The LIHCs show high electrochemical performance output intermediate between LIBs and ECs. The second part of the dissertation focused on the fast cycling of lithium titanate anode in ionic liquid-based electrolyte for LIHC. It was shown that porous binder-free LTO electrode prepared by electrostatic spray deposition (ESD) delivered better fast-cycling capability than conventional electrode preparation method comprising polymer binder. In the last part of the dissertation, on-chip LIHC with three dimensional (3D) interdigital carbon microelectrode platform derived carbon microelectromechanical systems (C-MEMS) technique by was fabricated and examined. The 3D carbon structures played the dual role of the current collector and capacitor electrode, while LiFePO4 was employed as the battery electrode. The on-chip LIHC generated a maximum footprint area normalized energy density of about 5.03 μWcm-2, which was about five times more than symmetric ECs of the same footprint area. Capacitor ; Energy storage ; Materials science ; Capacitive sensing ; Electrochemistry ; Lithium (medication) ; Electrochemical energy storage ; Ion ; Electrical engineering ; Supercapacitor ; Optoelectronics ; Power (physics) ; Chemistry ; Engineering ; Electrode ; Voltage ; Physics Supercapacitor Materials and Fabrication ; Advanced Battery Technologies Research ; Electric and Hybrid Vehicle Technologies
Authors: Ludmila Otilia Cinteză | Daniela Bala | Adina Răducan | Cristina Scomoroşcenco | Elvira Alexandrescu | Cristina Lavinia Nistor | Cristian Petcu | Laura Chirilă | Ioana Stănculescu
Source:  (article, 2019-10-14)
Field: Materials Science — Surfaces, Coatings and Films

Novel Coatings for Superhydrophobic/Superamphiphobic Surfaces with Tunable Morphology of Nanoparticles Functional surfaces with special wettability properties are currently receiving a lot of attention [...] Nanotechnology ; Nanoparticle ; Humanities ; Library science ; Engineering ; Materials science ; Art ; Computer science Surface Modification and Superhydrophobicity ; Electrohydrodynamics and Fluid Dynamics ; Plasma Diagnostics and Applications
Authors: Benjamin Kiendl
Source: Online Publication Service of Würzburg University (Würzburg University) (article, 2019-04-17)
Field: Materials Science — Materials Chemistry

Application of diamond nanomaterials in catalysis In this work the catalytic activity of nanodiamond particles with different dopants and surface terminations and of diamond nanomaterials funtionalized with ruthenium-based photocatalysts was investigated, illustrating materials application in photoredox chemistry and the photo(electro)catalytic reduction of CO2. Regarding the application of diamond nanomaterials in photocatalysis, methods to fabricate and characterize several (un)doped nanoparticles with different surface termination were successfully developed. Various photocatalysts, attached to nanodiamond particles via linker systems, were tested in photoredox catalysis and the photo(electro)catalytic reduction of CO2. Nanodiamond ; Nanomaterials ; Photocatalysis ; Nanotechnology ; Catalysis ; Materials science ; Diamond ; Dopant ; Nanoparticle ; Photoredox catalysis ; Doping ; Chemistry ; Organic chemistry ; Metallurgy ; Optoelectronics Catalytic Processes in Materials Science ; Advanced Photocatalysis Techniques
Authors: Kévin Renault | Sylvain Debieu | Jean‐Alexandre Richard | Anthony Romieu
Source: ChemRxiv (preprint, 2019-08-12)
Field: Chemistry — Organic Chemistry

Deeper Insight into the Protease-Mediated Formation of Pyronin Dyes and Possible Implications in the Design of Fluorogenic Probes for Bioimaging and Theranostic Prodrugs We report a rational and systematic study devoted to structural optimisation of a novel class of protease-sensitive fluorescent probes recently reported by us (&lt;i&gt;Org. Biomol. Chem.&lt;/i&gt;, 2017, &lt;b&gt;15&lt;/b&gt;, 2575-2584), based on the "covalent-assembly" strategy and using the targeted enzyme (penicilin G acylase as model protease) to build a fluorescent pyronin dye by triggering a biocompatible domino cyclisation-aromatisation reaction. The aim is to identify &lt;i&gt;ad hoc&lt;/i&gt; probe candidate(s) that might combine fast/reliable fluorogenic "turn-on" response, full stability in complex biological media and ability to release a second molecule of interest (drug or second fluorescent reporter), for applications in disease diagnosis and therapy. We base our strategy on screening a set of active methylene compounds (C-nucleophiles) to convert the parent probe to various pyronin caged precursors bearing Michael acceptor moieties of differing reactivity. &lt;i&gt;In vitro&lt;/i&gt; stability and fluorescent enzymatic assays combined to HPLC-fluorescence analyses provide data useful to define the most appropriate structural features for these fluorogenic scaffolds depending on the specifications required by the biomedical application (&lt;i&gt;e.g.&lt;/i&gt;, &lt;i&gt;in vivo&lt;/i&gt; molecular imaging, image-guided drug delivery and theranostics) for which they will be used. Chemistry ; Rational design ; Protease ; Fluorescence ; Combinatorial chemistry ; Prodrug ; Drug discovery ; Drug delivery ; Enzyme ; Biochemistry ; Nanotechnology ; Organic chemistry ; Materials science Click Chemistry and Applications ; Biotin and Related Studies
Authors: Eric P. Choate
Source: Carolina Digital Repository (University of North Carolina at Chapel Hill) (article, 2019-08-12)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Small amplitude oscillatory flows of nematic liquid crystal polymers This dissertation presents two theoretical predictions of the behavior of solutions of nematic liquid crystal polymers when subjected to small amplitude flows that are oscillatory in time. First, we review theoretical models for predicting the behavior of nematic liquid crystals, including Leslie-Ericksen theory, which only attempts to capture the mean direction of molecular orientation, and Doi-Hess kinetic theory, which defines a probability density function on the unit sphere for the molecular orientation and also the mesocscopic orientation tensor models derived from it, which are the models that we will examine. In Chapter 2, we examine shear flow in the monodomain limit, in which there are no spatial gradients in molecular orientation, and we use multiple timescale perturbation analysis to capture very slowly developing effects in the dynamic moduli, similar to experimental observations. Then, in Chapter 3, we relax the monodomain restriction and examine the effect of heterogeneity in the molecular orientation and the choice of two special anchoring conditions for the orientation at the plates. We re- cover a Leslie-Ericksen-type prediction, formally connect imposed stress and imposed velocity boundary conditions in shear flow, and establish an equivalence at the level of the storage and loss moduli between shear flow and Poiseuille flow. Liquid crystal ; Amplitude ; Materials science ; Polymer ; Condensed matter physics ; Optics ; Physics ; Composite material ; Optoelectronics Liquid Crystal Research Advancements ; Nonlinear Dynamics and Pattern Formation ; Surfactants and Colloidal Systems
Authors: Seiya Fukagawa | M. Kojima | Tatsuhiko Yoshino | Shigeki Matsunaga
Source: Institutional Repositories DataBase (IRDB) (article, 2019-10-08)
Field: Chemistry — Organic Chemistry

Catalytic Enantioselective Methylene C(sp(3))-H Amidation of 8-Alkylquinolines Using a Cp*Rh-III/Chiral Carboxylic Acid System Catalytic enantioselective directed methylene C(sp(3))-H amidation reactions of 8-alkylquinolines using a Cp*Rh-III/chiral carboxylic acid (CCA) hybrid catalytic system are described. A binaphthyl-based chiral carboxylic acid efficiently differentiates between the enantiotopic methylene C-H bonds, which leads to the formation of C-N bonds with good enantioselectivity. Enantioselective synthesis ; Catalysis ; Methylene ; Carboxylic acid ; Propionates Catalytic C–H Functionalization Methods ; Synthesis and Catalytic Reactions ; Asymmetric Synthesis and Catalysis
Authors: Sol Lee | Yangjin Lee | Jun-Yeong Yoon | Kwanpyo Kim
Source: Microscopy and Microanalysis (article, 2019-08-01)
Field: Materials Science — Materials Chemistry

TEM Imaging and Electron Diffraction of Vertically Stacked Graphene/h-BN with Fine Control of Twist Angle Vertical heterostructures incorporating two-dimensional (2D) atomically-thin crystals have attracted significant research interest owing to their novel physical properties arising from interlayer interaction Relatively weak van der Waals force is a main interaction between layers, which enables preparation of isolate layers and fabrication of vertical heterostructure through various bottom-up approaches. The twist angle between neighboring layers in a vertical stack is a degree of freedom which strongly influences the various properties. In particular, a vertical heterostructure can display in-plane atomic-scale reconstruction associated with inhomogeneous strain due to a competition between the in-plane strain energy and inter-layer stacking energy, especially for near-commensurate interlayer stacking condition. The process to build vertical structure with fine control of twist angle is therefore of critically importance. Twist ; Graphene ; Materials science ; Electron diffraction ; Diffraction ; Optics ; Nanotechnology ; Physics ; Geometry Graphene research and applications ; 2D Materials and Applications ; MXene and MAX Phase Materials
Authors: Sérgio Luiz Mineiro | Helen Beatriz Ferreira | João Marcos Kruszynski de Assis | Maria do Carmo de Andrade Nono
Source: ABM Proceedings (article, 2019-10-01)
Field: Materials Science — Materials Chemistry

ANÁLISE MICROESTRUTURAL E DA FORMAÇÃO DA FASE PEROVSKITA EM CERÂMICA DE MANGANITA DE LANTÂNIO DOPADA COM ÓXIDO DE ESTRÔNCIO A manganita de lantânio no sistema La-Sr-Mn-O recebe grande atenção da comunidade científica por apresentar temperatura de Curie próxima da temperatura ambiente, tornando-a interessante para aplicações tecnológicas por suas propriedades ótica, elétrica e magnética.Outra característica interessante para a área espacial é que a sua emissividade é variável, o que confere a esta cerâmica auxílio no controle de temperatura, justificando sua importância na aplicação em controle térmico de satélites.Neste trabalho foram preparadas amostras de LaMnO 3 com dopagem de óxido de estrôncio, com o objetivo de substituição de íons La 3+ na estrutura perovskita por íons Sr 2+ .As caracterizações do material foram realizadas para o estudo da formação da estrutura perovskita, pelo método de Rietveld, e a microestrutura após a sinterização das cerâmicas em temperaturas na faixa de 1300 a 1400 °C.Na calcinação os pós apresentaram fases intermediárias além da formação e progressivo aumento da fase perovskita a cada ciclo de processamento utilizado.Na sinterização a composição La 0,875 Sr 0,125 MnO 3 resultou na maior quantidade calculada, porém, mesmo com a maior temperatura de sinterização utilizada fases intermediárias também foram identificadas.Quanto à análise microestrutural foi observado que as cerâmicas apresentaram porosidade residual e microestrutura mais densa com a aplicação de maior temperatura, resultados compatíveis com os valores de densidade relativa calculados. Humanities ; Materials science ; Art Catalytic Processes in Materials Science ; Magnetic and transport properties of perovskites and related materials ; Advancements in Solid Oxide Fuel Cells
Authors: A. Muthuvinothini | S. Stella
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2019-01-01)
Field: Chemistry — Organic Chemistry

A detailed study on the effect of side chains of amino acids for the synthesis of zinc nanoparticles Department of Chemistry &amp; Research Centre, Sarah Tucker College (Autonomous), affiliated to Manonmaniam Sundaranar University, Tirunelveli-627 007, Tamilnadu, India <em>E-mail</em>: stella.selvaraj@gmail.com <em>Manuscript received online 28 August 2018, accepted 09 October 2018</em> In the present work, a simple one-step synthetic method was demonstrated for the synthesis of zinc nanoparticles using amino acids as reducing and stabilizing agents in aqueous medium. The formation of the nanoparticles was strongly influenced by varying the pH of the solution and the structure of the amino acid. The yield and properties of the synthesized amino acids capped zinc nanoparticles were compared. The synthesized nanoparticles were characterized by using UV-Vis and FT-IR spectral studies. Zinc ; Nanoparticle ; Side chain ; Amino acid ; Chemistry ; Combinatorial chemistry ; Organic chemistry ; Nanotechnology ; Materials science ; Biochemistry ; Polymer Nanomaterials for catalytic reactions
Authors: Marco Fiore | Nicola Modugno | Francesco Pellegrini | Mariagrazia Roselli
Source:  (article, 2019-09-09)
Field: Chemistry — Organic Chemistry

SOLID-STATE MICROWAVE PROCESSOR FOR FOOD TREATMENT Uneven heating and hot spots, irregular matching conditions and deterioration of organoleptic qualities are typical drawbacks of magnetron-based food processing with microwave radiation. The proposed “Kopernicook” modular architecture, based on multiple solid-state generators governed by a distributed software platform, allows highly accurate parametric control, full customization of radiation patterns and dynamic self-regulating workflows. The first results, validated with industrial applications, show great flexibility of operation, optimal energy consumption and different ideas for future developments in terms of radiation patterns and feedback-triggered algorithms aimed at maximally efficient processes. Modular design ; Computer science ; Workflow ; Flexibility (engineering) ; Software ; Microwave ; Solid-state ; Personalization ; Distributed computing ; Embedded system ; Engineering ; Telecommunications ; Operating system Microwave-Assisted Synthesis and Applications