jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Yasmi Reyes‐Ortega | Cándida Pastor‐Ramírez | Sylvain Bernès | R. Zamorano | Daniel Ramı́rez-Rosales | Samuel Hernández‐Anzaldo
Source:  (article, 2018-05-21)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Tetramer compound of manganese ions with mixed valence [Mn&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;II&lt;/sup&gt;Mn&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;IV&lt;/sup&gt;] and its spatial, electronic and magnetic studies. In this work we report the synthesis, structural, electronic and magnetic characterization of [MnIV2MnII2(HL)2(H2L)2(H2O)4](NO3)2 &nbsp;1. This novel compound was obtained from (E)-2-((2-hydroxybenzylidene)amine)-2-(hydroximethyl-propane-1,3-diol, (H4L) and Mn(NO3)2. The UV-Vis and IR spectrophotometry showed the typical d-d transitions of MnIV in and octahedral geometry compounds 1 and vibrational transitions in 477 cm-1, which is assigned to the Mn-O group 2. The cM vs T gave J = 164 cm-1 3. The ESR (g = 11.03, 4.87, 1.78, and g = 3.23, 2.03) analysis of 1 showed the presence of MnII (s = 5/2) and MnIV (s = 3/2) ions within the molecule. The hyperfine interaction is observed in ESR spectrum which showed two species of Mn ions4. An x ray diffraction suitable monocristal of 1 was obtained and its structure was possible to describe as a tetramer of [MnIV MnII MnII MnIV] building a 2D stepped supramolecular structure with a step of [MnIV&ndash;O-O-MnII] and a second step with [MnII&ndash;O-O-MnIV]. The structural study informed us that each magnetic box of [MnIV-O-O-MnII] have a superexchange antiferromagnetic interaction by the dx2-y2-sp3 (with more contribution of p orbitals) orbitals; however, among the boxes or steps there is a super-exchange ferromagnetic interaction, by oxo bonds MnII-O-MnII. Ye T., Li S., Wu X., Xu M., Wei X., Wang K., Bao H., Wang J. and Chen J. J. Mater. Chem. C, 2013, 1, 4327&ndash;4333. Lever A. B. P. Inorganic Electronic Spectroscopy. 2a Edition. Elsevier, 1997. Czernuszewicz S. R., Su O. Y., Stern K. M., Macor A. K., Kim D., Groves T. J. and Spiro G. T. Am. Chem. Soc. 1988, 110, 4158-4165. Nakamoto K. Infrared and Raman Spectra of Inorganic and Coordination Compounds. 6a edition, John Wiley &amp; Sons, 2009. Yoo J., Brechin E., Yamaguchi A., Nakano M., Huffman C. J., Maniero L. A., Brunel L. C., Awaga K., Ishimoto H., Christou G. y Hendrickson D. Chem. 2000, 39, 3615-3623. Milios J. C., Piligkos S., Bell R. A., Laye H. R., Teat J. S., Vicente R., McInnes E., Escuer A., Perlepes P. S. y Winpenny P. E. R. Inorganic Chemistry Communications. 2006, 9, 638&ndash;641. Ram&iacute;rez R. D., Zamorano U. R., P&eacute;rez M. O. Solid State Communications. 2001, 118, 371-376. Superexchange ; Crystallography ; Antiferromagnetism ; Manganese ; Chemistry ; Valence (chemistry) ; Ferromagnetism ; Octahedron ; Tetramer ; Molecule ; Magnetic susceptibility ; Ion ; Crystal structure ; Physics ; Condensed matter physics Magnetism in coordination complexes ; Lanthanide and Transition Metal Complexes ; Metal-Organic Frameworks: Synthesis and Applications
Authors: Gabriel Gil | Guido Goldoni | Stefano Corni
Source:  (article, 2018-11-01)
Field: Materials Science — Materials Chemistry

Enhanced light-harvesting of protein-pigment complexes assisted by a quantum dot antenna We predict the enhanced light harvesting of a protein-pigment complex when assembled to a quantum dot (QD) antenna. Our prototypical nanoassembly setup is composed of a Fenna-Mattews-Olson system hosting 8 Bacteriochlorophyll (BChl) a dyes, and a near-infrared emitting CdSe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Te <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(1−x)</inf> /ZnS alloy-core/shell nanocrystal. BChl a has two wide windows of poor absorption in the green and orange-red bands, precisely where most of the sunlight energy lies. The selected QD is able to collect sunlight efficiently in a broader band and funnel its energy by a (non-radiative) Förster resonance energy transfer mechanism to the dyes embedded in the protein. By virtue of the coupling between the QD and the dyes, the nanoassembly absorption is dramatically improved in the poor absorption window of the BChl a. Quantum dot ; Absorption (acoustics) ; Bacteriochlorophyll ; Energy transfer ; Resonance (particle physics) ; Quantum ; Absorption band ; Coupling (piping) Quantum Dots Synthesis And Properties ; Photosynthetic Processes and Mechanisms ; Advanced biosensing and bioanalysis techniques
Authors: Surendra Thapa
Source: UNM’s Digital Repository (University of New Mexico) (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

Copper-Catalyzed Direct and Tandem Couplings, and Mechanistic Studies Cross-coupling reactions are exceptionally powerful tools to construct carbon-carbon (C-C) bonds. These reactions are widely used to synthesize natural products, polymers, agrochemical, organic materials and pharmaceutical compounds. However, these reactions are typically catalyzed by Palladium. Although these reactions are widely utilized and well developed, the use of noble metals like Pd raises a question about its long-term sustainability. We believe copper can be one of the best alternatives to palladium as it is more abundant, less expensive and less toxic. In addition, Pd-catalyzed transformations usually suffer from β-hydride elimination to afford undesired olefin and rearranged products, when it comes to the coupling of alkylorganometallic reagents bearing β-hydrogen. In this respect, we have so far developed Cu-catalyzed cross-couplings of organometallic reagents of B, Si, In, Zr and Zn with alkyl, aryl, and heteroaryl halides. Our results show that copper is less likely to suffer from β-hydride elimination and tolerates heteroaryl halides very effectively. We discovered that CuI-salts with and without ligands are efficient catalysts for the coupling of alkylorganometallic reagents of In and Zn with electron-deficient aryl iodides and heteroaryl halides. Primary alkylorganometallic reagents afford coupled products in good to excellent yields. Reactions of secondary alkylindium and alkylzinc, and tertiary alkylzinc reagents proceeded without complications from β-hydride elimination and afforded products without rearrangement. This property of Cu also enabled us to develop tandem cyclization-coupling of olefin-tethered organozinc reagents that possess β-hydrogens. This reaction enabled us to synthesize complex carbo- and N/O-heterocycles that are found as privileged motifs in a wide variety of pharmaceuticals and natural products. In addition, the unique reactivity of Cu-catalysts allows ‘ligandless’ cross-couplings for aryl-heteroaryl and heteroaryl-heteroaryl bond formation. We were also able to synthesize and characterize different ligated CuI-complexes and show their reactivity towards aryl iodides. Our investigation also helped to understand the underlying mechanism of CuI-catalyzed coupling reactions, and these studies suggest that the Cu-catalyzed couplings with organosilicon, organoboron, organoindium and organozirconium reagents are less likely to involve any free radicals. In addition, our investigation revealed that the transmetallation with the neutral arylboronate ester was a two-step process that proceeded via the formation of a cation-anion pair complex. Tandem ; Catalysis ; Copper ; Chemistry ; Materials science ; Biochemistry ; Organic chemistry Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods ; Asymmetric Hydrogenation and Catalysis
Authors: Alain C. Tagné Kuate | Roger A. Lalancette | Thomas Bannenberg | Frieder Jäkle
Source: Angewandte Chemie (article, 2018-04-10)
Field: Chemistry — Organic Chemistry

Diferrocenylmercury‐Bridged Diphosphine: A Chiral, Ambiphilic, and Redox‐Active Bidentate Ligand Abstract A diphosphine chelate ligand with a wide and flexible bite angle, a unique stereochemical environment, and redox‐active and ambiphilic character is reported. Initially generated as its HgCl 2 complex by reaction of 1,2‐fc(PPh 2 )(SnMe 3 ) (fc=ferrocenediyl) with HgCl 2 in acetone, treatment with [ n ‐Bu 4 N]CN readily liberates the free chiral bidentate ligand. An intermolecular ClHg−Cl→Hgfc 2 (2.9929(13) Å) interaction that is unprecedented in ambiphilic ligand chemistry is seen in the solid structure of Hg(fcPPh 2 ) 2 ⋅HgCl 2 where the bridging mercury atom acts as a σ‐acceptor. Furthermore, a bis‐[Rh(COD)Cl] complex is introduced, which displays relatively short Rh⋅⋅⋅Hg contacts of 3.4765(5) and 3.4013(1) Å. Wiberg indices of 0.12 are determined for these Rh⋅⋅⋅Hg interactions and an AIM analysis reveals bond paths with an electron density ρ ( r ) of 1.2×10 −2 and 1.4×10 −2 e/a 0 3 at the bond critical points. Chemistry ; Denticity ; Ligand (biochemistry) ; Bite angle ; Stereochemistry ; Chelation ; Crystallography ; Crystal structure ; Inorganic chemistry Organometallic Complex Synthesis and Catalysis ; Synthesis and characterization of novel inorganic/organometallic compounds ; Organoboron and organosilicon chemistry
Authors: Yaşar Gök | Seda Kılıçarslan
Source: Croatica Chemica Acta (article, 2018-01-01)
Field: Chemistry — Inorganic Chemistry

Synthesis of C2-Symmetric Bisphosphines and Their Application in Enantioselective Transition Metal Catalysis C2-symmetric bisphosphine ligands (with a dioxolane backbone) have been synthesized by using corresponding chiral bromosubstituted hydrobenzoin derivatives in two steps with moderate yields. The last step for desired bisphosphines defined the electronic and steric properties of the chelating atoms by the treatment of aryl or alkyl substituted chlorophosphine compounds in the presence of a base. These synthesized ligands have been evaluated in different catalytic reactions. The first application has been the palladiumcatalyzed enantioselective allylic alkylation which is regarded as a remarkable reaction for forming enantioselective carbon-carbon bond (up to 63 % ee and 98 % chemical yield). The ruthenium-catalyzed enantioselective transfer hydrogenation reaction has been the second application for the evaluating of the catalysts (up to > 99 % conversion with no enantioselectivity). Enantioselective synthesis ; Catalysis ; Transition metal ; Chemistry ; Combinatorial chemistry ; Computational chemistry ; Stereochemistry ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Asymmetric Synthesis and Catalysis ; Organometallic Complex Synthesis and Catalysis
Authors: Cátia D. F. Martins | M. Manuela M. Raposo | Susana P. G. Costa
Source:  (article, 2018-11-14)
Field: Chemistry — Spectroscopy

Metallic Ion Sensing with a Benzothiazole-Based Fluorimetric Chemosensor An unnatural amino acid derivative, N-tert-butyloxycarbonyl asparagine benzyl ester bearing a benzothiazole unit at the side chain, was evaluated as a fluorimetric chemosensor for several transition metal cations with environmental, biological and analytic relevance. Spectrofluorimetric titrations of the heterocyclic asparagine derivative with the various ions were carried out in acetonitrile and acetonitrile/water (9:1). It was found that the unnatural amino acid had a remarkable fluorimetric response in the presence of Cu2+ in acetonitrile and in the presence of Fe3+ in acetonitrile/water (9:1). Benzothiazole ; Acetonitrile ; Chemistry ; Titration ; Metal ions in aqueous solution ; Derivative (finance) ; Fluorescence ; Ion ; Organic chemistry ; Photochemistry Molecular Sensors and Ion Detection ; Analytical Chemistry and Sensors ; Advanced biosensing and bioanalysis techniques
Authors: Veselin Kirov | Alexander Tchoukanov | A. K. Hallak | Bayko Baykov
Source: International Journal of Current Microbiology and Applied Sciences (article, 2018-07-10)
Field: Chemistry — Spectroscopy

New Criteria for Chemical Heterogeneity of the Biosphere 2. Distribution of Cadmium and Lead in the Egg of Hens There have been experiments with laying hens divided into 4 groups which receive rations with different amounts of lead and cadmium. The amount and distribution of the two toxic elements in the egg components have been studied and the environmental risk for human food use has been assessed. Two new criteria defining the chemical heterogeneity of the biosphere at sub-organismal level have been devised: Clark of distribution and Clark of safety. These criteria are proposed to increase the effectiveness of management. Disparities in the distribution of the tested elements in the egg white, egg yolk and shell and the degree of safety for human health have been found. Cadmium ; Yolk ; Biosphere ; Distribution (mathematics) ; Human health ; Egg white ; Environmental science ; Biology ; Ecology ; Chemistry ; Environmental health ; Food science ; Mathematics ; Medicine Adsorption, diffusion, and thermodynamic properties of materials ; Chemical Thermodynamics and Molecular Structure ; Soil and Environmental Studies
Authors: Alena Shchelokova | Alexey Slobozhanyuk | Irina V. Melchakova | Stanislav Glybovski | Andrew Webb | Yuri S. Kivshar | Pavel A. Belov
Source: Physical Review Applied (preprint, 2018-01-18)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Locally Enhanced Image Quality with Tunable Hybrid Metasurfaces Magnetic resonance imaging (MRI) is one of the most important noninvasive imaging techniques for human diagnostic medicine. Over the decades MRI quality has improved substantially, through the design of very sensitive multichannel receivers, but designs based on conventional materials are nearly topped out in terms of performance. Thus artificial materials are sought to further boost MRI sensitivity. The authors demonstrate a type of metasurface that can dramatically enhance MRI image quality, allowing the resolution of smaller features of tumors, for example, much more quickly and efficiently. Metamaterial ; Coupling (piping) ; Quality (philosophy) ; Photonics ; Dielectric ; Image quality ; Computer science ; Optoelectronics ; Sensitivity (control systems) ; Materials science ; Permittivity ; Optics ; Physics ; Image (mathematics) ; Electronic engineering ; Artificial intelligence ; Engineering Metamaterials and Metasurfaces Applications ; Antenna Design and Analysis ; Advanced Antenna and Metasurface Technologies
Authors: Grant Henson | Clyde S. Jone
Source: NASA STI Repository (National Aeronautics and Space Administration) (article, 2018-08-01)
Field: Materials Science — Materials Chemistry

Chapter 7: Materials for Launch Vehicle Structures This chapter concerns materials for expendable and reusable launch vehicle (LV) structures. An emphasis is placed on applications and design requirements, and how these requirements are met by the optimum choice of materials. Structural analysis and qualification strategies, which cannot be separated from the materials selection process, are described. Launch vehicle ; Process (computing) ; Systems engineering ; Engineering ; Material selection ; Selection (genetic algorithm) ; Computer science ; Construction engineering ; Aerospace engineering ; Materials science Silicone and Siloxane Chemistry ; Spacecraft and Cryogenic Technologies ; Structural Analysis and Optimization
Authors: Ana Dinora Guzman–Chavez | Vargas-Rodriguez Everardo
Source: Sensors and Materials (article, 2018-12-10)
Field: Chemistry — Spectroscopy

Optical Gas Sensor Based on the Fiber Laser Transient Regime for Measuring Acetylene An optical gas sensor based on an erbium-doped fiber laser (EDFL) for measuring acetylene (C 2 H 2 ) is presented. Here, by taking advantage of the thermooptic properties of a silicon (Si) wafer, the fiber laser emission line is set at 1532.81 nm, where a strong ro-vibrational absorption of the acetylene molecule occurs. Moreover, in our setup, the gas concentration induces cavity losses that affect laser transient characteristics. Here, by measuring the time delay ( d ) from the laser transient, it was possible to measure the C 2 H 2 concentration within the range from 0 to 22% with a sensitivity of 1.17 10 -2 ms/% and a minimum detectable concentration of 942 ppm. Finally, it is shown that the sensor requires only 18.5 ms to complete a measurement. Acetylene ; Transient (computer programming) ; Optical fiber ; Fiber optic sensor ; Laser ; Materials science ; Optoelectronics ; Optics ; Computer science ; Chemistry ; Physics ; Organic chemistry ; Operating system Spectroscopy and Laser Applications ; Analytical Chemistry and Sensors ; Gas Sensing Nanomaterials and Sensors
Authors: C. Vinodhini | K.V. Deshmukh | Ajay Kumar Srivastava
Source: International Journal of Current Microbiology and Applied Sciences (article, 2018-10-10)
Field: Chemistry — Inorganic Chemistry

Economic Analysis of Coconut Marketing and Constraints in Coconut Cultivation with Special Reference to Karur District of Tamil Nadu The paper mainly focuses on marketing of coconut in the study area. Also discusses the key issues in the production of coconut and its marketing, notices some important suggestions from the coconut growers. Channel I is predominantly found in the marketing of coconut in Karur district (Producer – Pre-harvest contractor – Wholesaler – Retailer – Consumer). The results revealed that in channel- I price received from pre-harvest contractor is Rs. 10000 while cost incurred by producer was Rs. 92. Thus net price received by producer is Rs. 9908 per 1000 nuts with 88.07 per cent producer’s share in consumer’s rupee. In channel – I marketing cost is Rs.1104 and marketing margin was Rs. 238. The results revealed that the major constraints faced by more than 81.25 per cent sample growers during production, is unawareness about technical information regarding post-harvest management practices, and in marketing of coconut, the major problem faced by more than 93.75 per cent of farmers was unawareness about various marketing practices. It is observed that nearly 73.75 per cent of coconut growers suggested to provide necessary credit in time and 56.00 per cent of coconut growers suggested to provide subsidies in case of any natural calamities like storm, flood etc. Tamil ; Business ; Biotechnology ; Agricultural economics ; Economics ; Biology ; Art Coconut Research and Applications ; Agricultural Economics and Practices ; Fisheries and Aquaculture Studies
Authors: W. J. Huang
Source: GSI Repository (GSI Helmholtzzentrum für Schwerionenforschung) (preprint, 2018-01-01)
Field: Chemistry — Spectroscopy

Direct Mass Measurements and Global Evaluation of Atomic Masses The Atomic Mass Evaluation (AME), started in the 1960s, is the most reliable source for comprehensive information related to atomic masses. It provides the best values for the atomic masses and their associated uncertainties by evaluating experimental data from decay, reactions, and mass spectrometry. In this thesis, the philosophy and the most important features of the Ame will be discussed in detail. The most recent developments of the latest mass table (AME2016), such as molecular binding energy, energy correction of the implantation measurements, and the relativistic formula for the alpha-decay process, will be presented. Another part of this thesis concerns the data analysis from the Penning-trap spectrometer ISOLTRAP at ISOLDE/CERN. The new results are included in the global adjustment and their influences on the existing masses are discussed. The last part of this thesis is related to the systematic error studies of the ISOLTRAP multi-reflection time-of-flight mass spectrometer, using an off-line ion source and the on-line proton beam. From the analysis of the selected measurements, I found that the systematic error is much smaller than the statistical uncertainties obtained up to now. Atomic mass ; Mass spectrometry ; Physics ; Penning trap ; Large Hadron Collider ; Nuclear physics ; Ion trap ; Computational physics ; Atomic physics ; Electron Mass Spectrometry Techniques and Applications ; SAS software applications and methods ; Scientific Research and Discoveries
Authors: Martin Judd | Session Chair | Dr Hassan Nouri | Andrea Mazza | ; Gianfranco | Chicco | Mohamed Darwish | Roya Ahmadi | Belen Garcia | ; Iii De Madrid | Joao Catalao | (inesc Tec | Feup | Keith Sunderland | * | Michael Conlon | Hassan Nouri | Markus Barwig | Thomas Drbaum | Thomas Hamacher | ; Da Silva | D Bernardon | R Delavechia | M Ortiz | R Milbradt | L Canha | ; | W Hokama | Fernando Maciel-Barbosa | Igor Gulyaev | ; Esmael Amin | M El-Dessouki | ; Hamouda
Source:  (article, 2018-09-01)
Field: Materials Science — Materials Chemistry

UPEC 2018 Technical Programme Measurement challenges in partial discharge diagnostics of high voltage insulation systems" Martin began his engineering career working on radar systems and components with Marconi and EEV in Lincoln. Moving to Glasgow in 1993 to join the University of Strathclyde, he pioneered ultra-high frequency (UHF) methods for partial discharge (PD) detection in gas insulated substations and transformers over a period of 20 years, becoming Professor in High Voltage Technologies and manager of Strathclyde's HV Laboratory. In 2014, he founded High Frequency Diagnostics, a company that supports the development of new electromagnetic wave sensor technologies and applications, particularly for high frequency sensing and diagnosis of PD activity in HV equipment. Martin is currently a UK representative on CIGRE JWG A2/D1.51 "Improvements to PD Measurements for FAT & SAT of Power Transformers." Computer science High voltage insulation and dielectric phenomena ; Power Line Inspection Robots ; Thermal Analysis in Power Transmission
Authors: Janice L. Pappas
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2018-11-13)
Field: Materials Science — Biomaterials

Quantified ensemble 3D surface features modeled as a window on centric diatom valve morphogenesis Abstract Morphological surface features are a record of genetic and developmental processes as well as environmental influences. The 3D geometric “terrain” of the surface consists of slopes via tangents, peaks and valleys via normals, smoothness of the transition between peaks and valleys, and point connections as flatness or curvature among all features. Such geometric quantities can be used to indicate morphological changes in valve formation over time. Quantified 3D surface features as geometric pattern ensembles may be representative of structural snapshots of the morphogenetic process. For diatoms, valve formation and pattern morphogenesis has been modeled using Turing-like and other algorithmic techniques to mimic the way in which diatoms exhibit the highly diverse patterns on their valve surfaces. How the created surface features are related to one another is not necessarily determined via such methods. With the diatom valve face structure of layered areolae, cribra, and other morphological characters, valve formation exhibits different combined geometries unfolding as 3D structural ensembles in particular spatial arrangements. Quantifying ensemble 3D surface geometries is attainable via models devised using parametric 3D equations and extracting surface features via partial derivatives for slopes, peaks and valleys, smoothness, and flatness as feature connectedness. Differences in ensemble 3D surface features may be used to assess structural differences among selected diatom genera as indicators of different valve formation sequences in surface generation and morphogenesis. Surface (topology) ; Tangent ; Flatness (cosmology) ; Biological system ; Curvature ; Morphogenesis ; Parametric surface ; Frustule ; Geometry ; Computer science ; Feature (linguistics) ; Diatom ; Principal curvature ; Algorithm ; Artificial intelligence ; Parametric statistics ; Mathematics ; Geology ; Biology ; Physics ; Mean curvature Diatoms and Algae Research ; Protist diversity and phylogeny ; Marine and coastal ecosystems