jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: S. M. A. Radmanesh
Source: ScholarWorks - UNO (University of New Orleans) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Ultra-low Temperature Properties of Correlated Materials Abstract After the discovery of topological insulators (TIs), it has come to be widely recognized that topological states of matter can actually be widespread. In this sense, TIs have established a new paradigm about topological materials. Recent years have seen a surge of interest in topological semimetals, which embody two different ways of generalizing the effectively massless electrons to bulk materials. Dirac and, particularly, Weyl semimetals should support several transport and optical phenomena that are still being sought in experiments. A number of promising experimental results indicate superconductivity in members of half-Hesuler semimetals which realize the mixing singlet and triplet pairing symmetry. We now turn to results we got through the work on topological semimetals. This work presents quantum high field transports on Dirac and Weyl topological semimetals including Sr1-yMn1-zSb2 (y, z < 0.1), YbMnBi2 and TaP. In case of Sr1-yMn1-zSb2 (y, z < 0.1), massless relativistic fermion was reported with m* = 0.04-0.05m0. This material presented a ferromagnetic order for in 304 K < T < 565 K, but a canted antiferromagnetic order with a net ferromagnetic component for T < 304 K. These are considered striking features of Dirac fermions For YbMnBi2, we reported the unusual interlayer quantum transport behavior in magnetoresistivity, resulting from the zeroth LL mode observed in this time reversal symmetry breaking type II Weyl semimetal. Also, for Weyl semimetal TaP the measurements probed multiple Fermi pockets, from which nontrivial π Berry phase and Zeeman splitting were extracted. Our ultra-low penetration depth measurements on half-Heuslers YPdBi and TbPdBi revealed a power- law behavior with n= 2.76 ± 0.04 for YPdBi samples and n=2.6 ± 0.3 for TbPdBi sample. We may conclude the exponent n > 2 implies nodless superconducting gap in our samples. Also, we found that despite the increase in magnetic correlations from YPdBi to TbPdBi, superconductivity remains robust in both systems which indicates that AF fluctuations do not play a major role in superconducting mechanism. Materials science Thermal properties of materials ; High-pressure geophysics and materials ; nanoparticles nucleation surface interactions
Authors: Aimee Fredericksen
Source: Iowa Research Online (The University of Iowa) (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

final, final frontier This project explores the concept of the frontier in science fiction, and beyond that, the way it can be expressed in poetry. As I've studied different variations of poems, I've often wondered what defines the boundaries between the conventional narratives found in the genre and fiction. I've been especially interested in whether a science fiction poetry exists, and if so, what conventions of the genre it is allowed to adhere to. My goal was to therefore present a collection of science fiction poetry. The poems concern themselves with the ideals of the frontier and their manifestation in a science fiction realm. The concept of the American frontier comes from the country's westward expansion during the 19th century. Frederick Jackson Turner presented his essay “The Significance of the Frontier in American History" at the end of the 19th century, advancing his Frontier Thesis, which establishes how the ideals of the frontier drove American history and its national identity. By 1890, the 11th U.S. Census declared an official end of the American western frontier. In the mid-20th century, the “space race” of the Cold War era presented a new frontier for competitive global powers to attempt to claim. Imaginations of space and the search for new frontiers became a large focus the sci-fi media to follow. This is especially evident in William Gibson's Sprawl trilogy, a tour de force of the cyberpunk subgenre which explores the occupation of a colonized space or the Internet as a frontier. Overall, the poems are largely concerned with the occupation of space, whether they be narratives that take place in outer space or quite literally play with form on the page. All of the poems represent a variety of fictional voices. While there is no overarching narrative, each piece is merely a facet of the ways we can consider science fiction. Following the patterns of contemporary speculative fiction that Brian Kim Stefans has traced, these poems, though disparate, converge into a collaborative work that spans the borders of these pages. Frontier ; Computer science ; Geography ; Archaeology Chemistry and Stereochemistry Studies
Authors: S. Taboukhat
Source: theses.fr (ABES) (preprint, 2018-07-12)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Study and diagnostic of nonlinear optical properties of highly conjugated organic and organometallic compounds for application in optoelectronic devices Les composés organiques et organométalliques représentent des matériaux prometteurs pour leurs applications dans divers domaines tels que l'optique non linéaire, l'optoélectronique, la photonique et le stockage des données par voie optique. Dans ce travail,nous avons étudié les propriétés optiques non linéaires(ONL) de deux familles de composés à savoir des molécules organiques à base de BODIPY et des complexes organométalliques à base de ruthénium (II)et de fer (II). Pour cette étude nous avons utilisé un laser pulsé en régime picoseconde qui délivre deux longueurs d'ondes : 1064 nm et 532 nm. Nous avons utilisé 1064nm pour les techniques de la génération de la seconde harmonique (SHG) et la génération de la troisième harmonique (THG) et 532 nm pour celle de Zscan.Les résultats obtenus sont intéressants et originaux et montrent bien que la réponse non linéaire dépend du nombre de groupements donneurs d’électrons pour les molécules organiques à base de BODIPY. Le même comportement a été observé dans le cas des complexes organométalliques à base de ruthénium (II) et de fer (II) mettant en évidence la modulation de la réponse optique non linéaire en fonction de la nature du métal de transition utilisé(Ru(II)ou Fe(II)) et de la nature des ligands auxiliaires autour du fragment organométallique (Ru(II)). Conjugated system ; Nonlinear optical ; Optoelectronics ; Materials science ; Nonlinear system ; Nanotechnology ; Physics ; Composite material ; Polymer Nonlinear Optical Materials Research ; Nonlinear Optical Materials Studies ; Optical and Acousto-Optic Technologies
Authors: Joyabrata Mal
Source:  (preprint, 2018-04-27)
Field: Materials Science — Materials Chemistry

Microbial Synthesis of Chalcogenide Nanoparticles Recent years have seen a growing interest in the application of chalcogenide nanoparticles (NPs), e.g. Se, Te, CdSe and CdTe NPs, in various industrial sectors including energy, petroleum refining and in the field of biology and medicine. Moreover, due to the high toxicity of chalcogen oxyanions, their release into the environment is of great concern. Thus, emphasis was given in this study on the development of a novel microbial synthesis process of chalcogenide NPs by combining biological treatment of Se/Te containing wastewaters with biorecovery in the form of Se NPs, Te NPs and CdSe NPs. Enrichment of Se-oxyanion reducing microorganisms was carried out to simultaneously remove selenite (Se(IV)) and cadmium (Cd(II)) from wastewaters by combining bioremediation of toxic Se-rich wastewater with the biorecovery of Se as CdSe NPs. The results showed compositional changes in the extracellular polymeric substances (EPS) matrix of the anaerobic granular sludge upon exposure to Cd(II) and Se(IV) and identified the roles of EPS fractions in the biogenesis of CdSe NPs. Besides, it was found that the EPS on the surface of the biogenic Se NPs play a major role in lowering the bioavailability and toxicity of biogenic Se(0) compared to chemogenic Se(0) NPs. An upflow anaerobic sludge blanket (UASB) reactor was used for the first time to continuously remove tellurite from wastewater and recover biogenic Te(0). Chalcogenide ; Nanoparticle ; Nanotechnology ; Materials science ; Metallurgy Quantum Dots Synthesis And Properties ; Chalcogenide Semiconductor Thin Films ; Advanced Nanomaterials in Catalysis
Authors: Phi H. Q. Pham
Source: eScholarship (California Digital Library) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Broadband Impedance Match to Monolayer Graphene in the Terahertz Domain The coupling of an electromagnetic plane wave to a thin conductor depends on the sheet conductance of the material. A poor conductor interacts weakly with the incoming light, allowing the majority of the radiation to pass. A good conductor does not absorb light and reflects the wave almost entirely. For suspended films, the transition from transmitter to reflector occurs when the sheet resistance is approximately the characteristic impedance of free-space (Z0 = 377 Ω). Near this point, the interaction is maximized, and the conductor absorbs strongly. We show that monolayer graphene, a tunable conductor, can be electrically modified to reach this transition, thereby achieving the maximum absorptive coupling across a broad range of frequencies in terahertz (THz) band. This interaction with an electromagnetic wave, to be a transmitter or absorber, is based on tunable electronic properties (rather than geometric structure), and is realized by bottom-up engineering of large-area monolayer graphene devices. Chemical vapor deposition is used to increase the graphene domain size and decrease grain boundaries. By using a fast two-step oxidized copper growth, individual graphene domains of 5-mm can be synthesized in less than 5-hours total growth duration. Following CVD synthesis, graphene transfer is optimized by removing bubbles that adhere to the graphene surface, and are transferred onto substrates modified by self-assembled monolayers (SAM), leading to improvement of the device on/off ratio. The high mobility graphene devices fabricated demonstrate the largest transmittance depth-of-modulation of THz waves to date, and by impedance matching devices using chemical doping, near maximum absorption is achieved. Graphene ; Terahertz radiation ; Materials science ; Monolayer ; Optoelectronics ; Sheet resistance ; Conductor ; Transmittance ; Chemical vapor deposition ; Electromagnetic radiation ; Wave impedance ; Optics ; Electrical impedance ; Nanotechnology ; Composite material ; Layer (electronics) ; Physics Graphene research and applications ; Photonic Crystals and Applications ; Metamaterials and Metasurfaces Applications
Authors: Nor-El-Houda Fardjaoui
Source: DIGITAL.CSIC (Spanish National Research Council (CSIC)) (article, 2018-06-27)
Field: Materials Science — Biomaterials

Synthèse des aluminosilicates de type géopolymères et zéolite LTA à partir des kaolins. Application à l’adsorption des métaux lourds (Cu(II), Cr(VI)) et des colorants textiles (jaune bezanyl, vert nylomine) Releases of varying micropollutants (anionic dyes, heavy metals…) in the environment are increasing, these pollutants, toxic and poorly degradable, are usually the source of many harmful health effects. Zeolite LTA was synthesized by the autoclave method, in alkaline medium, using the DD3 Algerian clay. The synthesized zeolite LTA can be efficiently used for bezanyl yellow (BY) and nylomine green (NG) adsorption (25 mg/L) at very low adsorbent doses (0.1 gzeolite LTA /gsolution), natural pH (~7) and temperatures below 60 °C. However, preliminary dilution of nylomine green (NG) containing effluents would decrease the steric hindrance of the sized NG molecules and improves therefore the adsorption capacities. On the other hand, very acidic and very alkaline pH improves the adsorption but enhances the zeolite dealumination. Freundlich isotherm and pseudo–second–order kinetics were found to be the most appropriate models to describe the removal of BY (Ea = 23.4±1 kJ/mol) and NG (Ea = 18.34 kJ/mol) from water. Free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes during physisorption were carefully evaluated at temperatures below 60 °C in order to avoid the contribution of thermodynamic parameters of dyes dissolution. The effect of simultaneously controlled humidity and temperature adopted in view to produce nanostructured geopolymers derived from metakaolin for functional applications was done. Geopolymer samples were prepared by dissolving high-quality metakaolin in water-glass solutions then cured and dried using well controlled humidity and temperature conditions for different aging times. Chemical stability, mechanical properties and sorption ability have been investigated with the aim to further explore their potential functional applications. Incorporation of polymers, such as alginic acid and pluronic-123, yields functional nanorachitectures that display ability for removal of heavy metal ions in solution (e.g. Cr VI and Cu II). Chemistry ; Aluminosilicate ; Adsorption ; Mineralogy ; Nuclear chemistry ; Physical chemistry ; Catalysis Clay minerals and soil interactions
Authors: Zülfi̇ye İlter | Zehra Ergen | S. Hakan Yilmaz
Source: Afyon Kocatepe University Journal of Sciences and Engineering (article, 2018-04-01)
Field: Chemistry — Organic Chemistry

Investigation of Thermal Properties and Reactivity Ratios of Acetyl Benzofuran Methacrylate Copolymers 2-asetil benzofuril metilmetakrilat (ABM) ve akrilonitril (AN), balatc olarak benzoil peroksit kullanlarak 60C'de 1,4-dioksan zcsnde serbest radikal polimerizasyonu ile hazrlanmtr. Kopolimer karakterizasyonu iin 1 H-NMR spektrofotometresi kullanlmtr. Kopolimerdeki monomer kompozisyonlar elementel analiz ile belirlenmi ve reaktivite oranlar (r1 ve r2) Finemann-Ross (FR) ve Kelen-Tds (KT) olmak zere eitli dorusal yntemler kullanlarak hesaplanmtr. ABM (1) ve AN (2)'nin reaktivite oranlar srasyla 6,67 ve 0,17 olarak tespit edilmitir. Molekl arl jel permasyon kromatografisi (GPC) ile belirlenmi, heterojendik indeksi (Mw/Mn) 1,13 olarak bulunmutur. Polimerlerin cams gei scakl Shimadzu DSC-50 ile incelenmi olup, cams gei scaklklarnn (Tg), kopolimerdeki polar monomer (ABM) konsantrasyonu arttka artt gzlenmitir. Polimerlerin termal analizi, Shimadzu TG-50 ile incelenmi ve kopolimerlerin yksek scakla dayankl olmad grlmtr. Copolymer ; Reactivity (psychology) ; Benzofuran ; Methacrylate ; Polymer chemistry ; Thermal ; Materials science ; Chemistry ; Organic chemistry ; Polymer ; Thermodynamics ; Physics Inorganic and Organometallic Chemistry ; Thermal and Kinetic Analysis ; Various Chemistry Research Topics
Authors: Aabid Mohd
Source: SPIRE - Sciences Po Institutional REpository (preprint, 2018-12-18)
Field: Chemistry — Inorganic Chemistry

Original chiral scaffolds bearing P-stereogenic centres Organic compounds having chirality on phosphorous atom, are called P-stereogenic, P-chirogenic or P-chiral compounds. These compounds are widely used in agrochemistry, pharmacy, coordination chemistry and in organometallic asymmetric catalysis, as one of the most important classes of chiral ligands (Nobel Prize 2001; W. S. Knowles). However, access to these P-stereogenic compounds, is challenging due to the complex, tedious and multi-steps synthetic methodologies. Herein, we report a highly efficient novel methodology to access P-stereogenic compounds, which often involves dynamic kinetic resolution (DKR) under modified Atherton-Todd reaction conditions, using a racemic H-phosphinate and an enantiopure phenol bearing a chiral sulfoxide moiety. Furthermore, the newly obtained O-P coupling product can potentially be post-functionalised under mild conditions to obtain various original P-stereogenic scaffolds. Thus, these O-P coupling products can be considered as highly potential precursors to access a variety of original P-stereogenic molecules. Stereocenter ; Enantiopure drug ; Enantioselective synthesis ; Moiety ; Chemistry ; Chirality (physics) ; Kinetic resolution ; Stereochemistry ; Combinatorial chemistry ; Catalysis ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Asymmetric Synthesis and Catalysis ; Organophosphorus compounds synthesis
Authors: Kyle Chan
Source: eScholarship (California Digital Library) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Phase Control and Processing Methods for High-Coercivity Magnets based on Metastable Fe2O3 High coercivity magnets are crucial in modern technology. Current state-of-the-art, high coercivity magnets rely on rare earth elements and/or precious metals which raises environmental and economic concerns. For this reason, the development of high-coercivity permanent magnetic materials comprised of earth-abundant and environmentally friendly materials is of world-wide interest. The focus of this work was the development of bulk, nanocomposite permanent magnetic materials based on the high-coercivity, metastable -Fe2O3 phase. A reverse-micelle/sol-gel process was used to synthesize Fe2O3/SiO2 core-shell structures, with Ba used as an aid in the formation of -Fe2O3 nanorods. Initial samples were prepared with an Fe/Ba concentration of 15 mol%. The SiO2 acted as a long range diffusion-mediating matrix, which allows for the controlled growth and stabilization of the metastable Fe2O3 phases. Annealing at 1050˚C resulted in -Fe2O3 nanorods with a maximum coercivity of 17.5 kOe. The diffusivity of Fe/O was increased through modification of the Si-O matrix with Na addition which resulted in -Fe2O3 nanorod formation with comparable dimensions and magnetic properties at 875˚C. This significant decrease in growth temperature confirms the hypothesis that -Fe2O3 stability is size dependent and is controlled by long range diffusion. Annealing experiments were also done using an externally applied magnetic field to investigate the effect of a magnetic field on the growth of nanometric Fe2O3. It was found that magnetic ordering was induced at 600°C, which is 300°C lower than samples annealed without field. The Si-O and Na-Si-O shells thicknesses were decreased to increase the Fe/Ba concentration, and therefore the magnetic content, to 90 mol%, resulting in samples with coercivites ≥13.0 kOe. Finally, bulk, high-coercivity magnets comprised primarily of the metastable -Fe2O3 phase were produced by rapidly densifying the composite Fe-O/Si-O composite powders via Current Activated Pressure Assisted Densification (CAPAD), followed by annealing. The Na-Si-O shell powders with 15 mol% Fe/Ba were also densified via CAPAD processing, resulting in relative densities ~99%, and high coercivites similar to the ideal Fe-O/Si-O powder samples. The nanocomposites produced in this work have some of the highest coercivities ever reported in dense millimeter-sized magnets that do not contain rare earths or precious metals. Coercivity ; Materials science ; Annealing (glass) ; Nanorod ; Magnet ; Metastability ; Nanocomposite ; Remanence ; Nanotechnology ; Condensed matter physics ; Chemical engineering ; Magnetization ; Metallurgy ; Magnetic field ; Chemistry ; Physics Magnetic Properties and Synthesis of Ferrites ; Magnetic Properties of Alloys ; Magnetic properties of thin films
Authors: Siti Nur E’zzati Mohd Apandi | Hazleen Anuar | Siti Munirah Salimah Abdul Rashid
Source: IIUM Engineering Journal (article, 2018-06-01)
Field: Materials Science — Biomaterials

ENVIRONMENTAL DEGRADATION OF DURIAN SKIN NANOFIBRE BIOCOMPOSITE To come up with a biodegradable alternative in reducing the use of polymer-based materials, polypropylene (PP) and durian skin nanofibre (DSNF) were melt-blended in a Haake internal mixer before compression moulded into composite specimens. The composites were exposed under ultraviolet (UV) radiation to simulate the effect of sunlight. The significant effect of maleic anhydride polypropylene (MAPP) was observed by the improvement recorded in tensile properties and reduction of water absorption in PP/DSNF composite. The colour index of composites increased with UV radiation exposure. Transmission electron microscope (TEM) images showed DSNF was well-dispersed in PP matrix in the presence of MAPP. Polypropylene ; Biocomposite ; Materials science ; Composite material ; Composite number ; Absorption of water ; Maleic anhydride ; Ultimate tensile strength ; Degradation (telecommunications) ; Polymer ; Copolymer Electrospun Nanofibers in Biomedical Applications
Authors: Magdalena Salazar | Palma General Chair | Jos Ignacio | Alonso Montes | Salazar Palma | Almudena Surez Rodrguez | Carlos Pedro | Daniel Segovia Vargas | Vicente Esbert | Ferran Martn | Eumc Chair | Tpc Chair | Teresa Guerrero | Jos ngel | Garca Garca | Eumic Chair | Mateo Burgos | Manuel Zurera | Wolfgang Heinrich | Vicente Boria | Esbert Eumc | Chair Ferran | Martn Eumc | Miguel ngel | Gmez Laso | Eumc Co-Chair | Francisco Ledesma | Carlos Camacho | Pealosa Co-Chair | Jos Garca | Garca Eumic | Tpc Co-Chair | ngel Mediavilla Snchez | Charles Campbell | J Sebastin Gmez-Daz | Gonzalo De | Miguel Vela | Eurad Co-Chair | Manuel Rosa | Zurera Eurad | Garca Chair | Pilar Amores | Esbert Teresa | Martn Guerrero | Garca Eumc | Chair Eumic | Chair Eurad | Almudena Surez | Rodrguez General | Juan-Mari Collantes | Daniel Vargas | Manuel Sierra Castaer | Luis Emilio | Garca Castillo | Jorge Ruiz-Cruz | Matthias Rudolph | Marc Van Heijningen | Cristina Andrei | Sara Barros | Justin King | P Pursula | A Lamminen | M Kantanen | J Saarilahti | V Ermolov | S Poltschak | M Freilinger | R Feger | A Stelzer | A Hamidipour | T Henriksson | M Hopfer | R Planas | S Semenov | A Afshaniaghajari | Ke Wu | J Bechter | F Roos | M Rahman | C Waldschmidt | F De Palo | G Galati | H Matsumura | Y Yagishita | I Soga | K Oishi | Y Kawano | Y Nakasha | T Iwai | G Gibiino | R Cinani | A Santarelli | F Filicori | Robert Weigel | Vittorio Euma | Gilles Dambrine | Patrice Gamand | Andrew Gibson | Willem Hol
Source:  (article, 2018-09-01)
Field: Chemistry — Organic Chemistry

EuRAD 2018 TOC Welcome to Madrid on behalf of the European Microwave Association (EuMA)! Our mission as EuMA is to promote microwaves in Europe and to foster networking between microwave scientists and engineers in Europe. We are pursuing this in various ways but our key event is the European Microwave Week. Computer science Microwave-Assisted Synthesis and Applications ; Microwave and Dielectric Measurement Techniques ; Educational Technology and Optimization