jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: María Celeiro | Rubén Acerbi | Abuzar Kabir | Kenneth G. Furton | Marı́a Llompart
Source: Analytica Chimica Acta X (article, 2019-12-17)
Field: Chemistry — Analytical Chemistry

Development of an analytical methodology based on fabric phase sorptive extraction followed by gas chromatography-tandem mass spectrometry to determine UV filters in environmental and recreational waters A novel method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been validated for the simultaneous determination of 11 UV filters (ethylhexyl salicylate, benzyl salicylate, homosalate, benzophenone-3, isoamylmethoxycinnamate, 4-methylbenzylidenecamphor, methyl anthranilate, etocrylene, 2-ethylhexylmethoxycinnamate, 2-ethylhexyl <i>p</i>-dimethylaminobenzoate, and octocrylene), in natural and recreational waters. Major experimental parameters affecting FPSE procedure have been optimized to obtain the highest extraction efficiency. Different types and sizes of sol-gel coated FPSE media, sample volume, extraction time, and type and volume of desorption solvent were evaluated. The optimal conditions involved the use of a (2.0 × 2.5) cm<sup>2</sup> FPSE device with PDMS based coating for the extraction of 20 mL of water for 20 min. The quantitative desorption of the target compounds was performed with 0.5-1 mL of ethyl acetate. The method was satisfactorily validated in terms of linearity, precision, repeatability and reproducibility. Recovery studies were performed at different concentration levels in real water matrices to show its suitability, obtaining mean values about 90% and satisfactory precision. LODs were at the low ng L<sup>-1</sup> in all cases. Finally, the validated FPSE-GC-MS/MS method was applied to different real samples, including environmental water (lake, river, seawater) and recreational water (swimming-pool), where 8 out of the 11 studied compounds were detected at concentrations between 0.12-123 μg L<sup>-1</sup>. FPSE is proposed as an efficient and simple alternative to other extraction and microextraction techniques for the analysis of UV filters in waters. Since no matrix effects were observed, quantification could be carried out by conventional calibration with standard solutions, without the need to perform the complete FPSE procedure, thus allowing a higher throughput in comparison with other microextraction techniques. Chromatography ; Extraction (chemistry) ; Mass spectrometry ; Solid phase extraction ; Tandem ; Tandem mass spectrometry ; Gas Chromatography/Tandem Mass Spectrometry ; Gas chromatography ; Gas chromatography–mass spectrometry ; Environmental science ; Chemistry ; Environmental chemistry ; Materials science Analytical chemistry methods development ; Effects and risks of endocrine disrupting chemicals ; Water Quality Monitoring and Analysis
Authors: Xiangmeng Chen | Zicong Chen | Chau Ming So
Source: The Journal of Organic Chemistry (article, 2019-05-02)
Field: Chemistry — Organic Chemistry

Exploration of Aryl Phosphates in Palladium-Catalyzed Mono-α-arylation of Aryl and Heteroaryl Ketones This paper presents the first general examples of selective palladium-catalyzed mono-α-arylation of aryl and heteroaryl ketones with aryl phosphates. The catalyst system, consisting of [Pd(2-butenyl)Cl]<sub>2</sub> and MorDalPhos, exhibited high catalytic reactivity toward this reaction. A wide range of aryl phosphates were efficiently coupled with aryl and heteroaryl ketones with good selectivity. Excellent-to-good product yields were afforded. The gram-scale reaction was conducted smoothly. Reductive elimination or transmetalation might be a rate-determining step in this reaction. Chemistry ; Transmetalation ; Aryl ; Catalysis ; Palladium ; Selectivity ; Combinatorial chemistry ; Organic chemistry ; Reactivity (psychology) ; Reductive elimination ; Medicinal chemistry Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods ; Catalytic Alkyne Reactions
Authors: Israa Haidar | Axelle Day | Philippe Decorse | Stéphanie Lau‐Truong | Alexandre Chevillot‐Biraud | J. Aubard | Nordin Félidj | Leı̈la Boubekeur-Lecaque
Source: Chemistry of Materials (article, 2019-02-24)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Tailoring the Shape of Anisotropic Core–Shell Au–Ag Nanoparticles in Dimethyl Sulfoxide Shape and size control of metal nanoparticles at the nanoscale is a crucial step in the development of diverse applications ranging from catalysis to plasmonics and surface-enhanced Raman spectroscopy (SERS). For the seed-mediated growth of nanocrystals, it is well established that the final morphology is dictated not only by the crystallinity of the seed but also by surfactant and additives. However, the systematic study of the impact and the fate of these additives to elucidate the growth mechanism remains challenging. Here, we show that the addition of dimethyl sulfoxide (DMSO) for the silver growth on gold nanorod seeds allows tailoring the shape of core–shell Au@Ag from truncated cuboids to octahedra. The combination of surface enhanced Raman scattering and X-ray photoelectron spectroscopies revealed the key role played by DMSO and its fate upon silver reduction. Nanorod ; Raman spectroscopy ; Dimethyl sulfoxide ; Materials science ; X-ray photoelectron spectroscopy ; Crystallinity ; Nanotechnology ; Nanoparticle ; Raman scattering ; Chemical engineering ; Nanocrystal ; Metal ; Chemistry ; Organic chemistry ; Composite material ; Optics Gold and Silver Nanoparticles Synthesis and Applications ; Nanocluster Synthesis and Applications ; Quantum Dots Synthesis And Properties
Authors: Jorn de Jong | Ben L. Feringa | Sander J. Wezenberg
Source: ChemPhysChem (article, 2019-10-17)
Field: Chemistry — Spectroscopy

Light‐Modulated Self‐Blockage of a Urea Binding Site in a Stiff‐Stilbene Based Anion Receptor Anion binding to a receptor based on stiff-stilbene, which is equipped with a urea hydrogen bond donating group and a phosphate or phosphinate hydrogen bond accepting group, can be controlled by light. In one photoaddressable state (E isomer) the urea binding site is available for binding, while in the other (Z isomer) it is blocked because of an intramolecular interaction with its hydrogen bond accepting motif. This intramolecular interaction is supported by DFT calculations and <sup>1</sup> H NMR titrations reveal a significantly lower anion binding strength for the state in which anion binding is blocked. Furthermore, the molecular switching process has been studied in detail by UV/Vis and NMR spectroscopy. The presented approach opens up new opportunities toward the development of photoresponsive anion receptors. Chemistry ; Hydrogen bond ; Intramolecular force ; Phosphinate ; Titration ; Urea ; Proton NMR ; Ion ; Binding site ; Photochemistry ; Stereochemistry ; Molecule ; Inorganic chemistry ; Organic chemistry Molecular Sensors and Ion Detection ; Luminescence and Fluorescent Materials ; Photochromic and Fluorescence Chemistry
Authors: Shuo Li | Junjie He | Petr Nachtigall | Lukáš Grajciar | Federico Brivio
Source: Physical Chemistry Chemical Physics (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Control of spintronic and electronic properties of bimetallic and vacancy-ordered vanadium carbide MXenes <i>via</i> surface functionalization MXenes are 2D transition metal carbides with high potential for overcoming limitations of conventional two-dimensional electronics. In this context, various MXenes have shown magnetic properties suitable for applications in spintronics, yet the number of MXenes reported so far is far smaller than their parental MAX phases. Therefore, we have studied the structural, electronic and magnetic properties of bimetallic and vacancy-ordered MXenes derived from a new (V<sub>2/3</sub>Zr<sub>1/3</sub>)<sub>2</sub>AlC MAX phase to assess whether MXene exfoliation would return stable magnetic materials. In particular, we have investigated the properties of pristine and surface-functionalized (V<sub>2/3</sub>Zr<sub>1/3</sub>)<sub>2</sub>CX<sub>2</sub> bimetallic and (V<sub>2/3</sub>□<sub>1/3</sub>)<sub>2</sub>CX<sub>2</sub> (where □ denotes the vacancies) vacancy-ordered MXenes (X = O, F and OH). Our density functional theory (DFT) calculations showed that modifying the MXene stoichiometry and/or MXene surface functionalization changes MXene properties. After testing all possible combinations of metallic motifs and functionalization, we identified (V<sub>2/3</sub>Zr<sub>1/3</sub>)<sub>2</sub>CX<sub>2</sub>, (V<sub>2/3</sub>□<sub>1/3</sub>)<sub>2</sub>CF<sub>2</sub> and (V<sub>2/3</sub>□<sub>1/3</sub>)<sub>2</sub>C(OH)<sub>2</sub> as stable structures. Among them, (V<sub>2/3</sub>Zr<sub>1/3</sub>)<sub>2</sub>CO<sub>2</sub> MXene is predicted to be an FM intrinsic half-semiconductor with a remarkably high Curie temperature (T<sub>C</sub>) of 270 K. The (V<sub>2/3</sub>Zr<sub>1/3</sub>)<sub>2</sub>C(OH)<sub>2</sub> MXene exhibits a rather low work function (WF) (1.37 eV) and is thus a promising candidate for ultra-low work function electron emitters. Conversely, the (V<sub>2/3</sub>□<sub>1/3</sub>)<sub>2</sub>CF<sub>2</sub> MXene has a rather high WF and hence can be used as a hole injector for Schottky-barrier-free contact applications. Overall, our proof-of-concept study shows that theoretical predictions of MXene exfoliation and properties support further experimental research towards developing spintronics devices. MXenes ; Surface modification ; Spintronics ; Vanadium ; Materials science ; Carbide ; Bimetallic strip ; Vanadium carbide ; Titanium carbide ; Nanotechnology ; Chemistry ; Ferromagnetism ; Condensed matter physics ; Physics ; Metallurgy ; Physical chemistry ; Metal MXene and MAX Phase Materials ; 2D Materials and Applications ; Ferroelectric and Negative Capacitance Devices
Authors: Tyler Smith | Andrew Steven | Bridget Bagert
Source: Ochsner Journal (review, 2019-01-01)
Field: Materials Science — Materials Chemistry

Gadolinium Deposition in Neurology Clinical Practice <b>Background:</b> Magnetic resonance imaging (MRI) enhanced with gadolinium-based contrast agents (GBCAs) is an essential tool in the diagnosis and management of many neurologic diseases, including multiple sclerosis, brain tumors, and infections. The clinical utility of GBCAs is evidenced by their widespread use. GBCAs are produced in macrocyclic and linear forms. Since 2014, evidence has suggested that repeated administration of GBCAs can lead to gadolinium deposition in the brain. <b>Methods:</b> We review the literature on gadolinium deposition, including both animal and human studies, as well as the literature on GBCA-associated health outcomes. Additionally, we summarize and discuss the updated medical society recommendations and perspectives on GBCA use in clinical practice. <b>Results:</b> The first publication reporting gadolinium deposition in the human brain was published in 2014. Since that seminal report, multiple studies have demonstrated that exposure to linear GBCAs is associated with gadolinium deposition in the dentate nucleus and globus pallidus as seen on brain MRI. Macrocyclic GBCA exposure has not convincingly been associated with gadolinium deposition evident on brain MRI. <b>Conclusion:</b> Clear evidence demonstrates that GBCAs lead to gadolinium deposition in the brain in a dose-dependent manner; however, only linear GBCAs have been associated with gadolinium deposition visualized on MRI. To date, no evidence links gadolinium deposition with any adverse health outcome. Updated medical society guidelines emphasize the importance of an individualized risk-benefit analysis with each administration of GBCAs. Medicine ; Neurology ; Clinical Practice ; Gadolinium ; Clinical neurology ; Medical physics ; Family medicine ; Neuroscience ; Psychiatry Lanthanide and Transition Metal Complexes ; Advanced MRI Techniques and Applications ; Medical Imaging Techniques and Applications
Authors: Qingguo Chen | Hongda Yang | Xinyu Wang | Heqian Liu | Kai Zhou | Xin Ning
Source: Polymers (article, 2019-02-28)
Field: Materials Science — Materials Chemistry

Dielectric Properties of Epoxy Resin Impregnated Nano-SiO2 Modified Insulating Paper Epoxy resin-impregnated insulation paper (RIP) composites are used as the inner insulation of dry condenser bushing in the ultra-high voltage direct current (UHVDC) power transmission system. To improve the dielectric properties of RIP, nano-SiO₂ is added to the insulation paper at concentrations of 0⁻4wt % before impregnation with pure epoxy resin. X-ray diffraction (XRD), scanning electron microscopy observations as well as the typical dielectric properties of relative permittivity, DC volume conductivity, DC breakdown strength, and thermally stimulated depolarization current (TSDC), were obtained. The effects of trap parameters on the breakdown field strength and volume conductivity were investigated. The DC breakdown electric field strength of the sample increased as the trap level increased. The maximum DC breakdown strength of nano-SiO₂-modified RIP was increased by 10.6% the nano-SiO₂ content of 2 wt %. The relative permittivity and DC volume conductivity were first decreased and then increased with increasing nano-SiO₂ content. These changes occurred near the interfaces between nano-SiO₂ and RIP. The increased DC breakdown strength was mainly attributed to the increased trap level. Epoxy ; Materials science ; Composite material ; Dielectric ; Nano- ; Composite epoxy material ; Optoelectronics High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Advanced Sensor and Energy Harvesting Materials
Authors: Marouen Hamdi | J. A. Poulis
Source: The Journal of Adhesion (article, 2019-11-20)
Field: Materials Science — Surfaces, Coatings and Films

Effect of UV/ozone treatment on the wettability and adhesion of polymeric systems The impact of UV/ozone treatment on the wettability and adhesion of ethylene propylene diene methylene (EPDM) rubber, polyvinyl chloride (PVC), and acrylonitrile butadiene styrene (ABS) was investigated using contact angle measurements, OWRK surface free energy model, standardized adhesion tests, and spectroscopic and microscopic observations. It is found that UV/ozone treatment enhances the wettability of the examined polymers. Also, it considerably improved the adhesion strength of PVC and ABS samples, and shifted their failure modes from adhesive to cohesive. FTIR-ATR characterization showed insignificant changes in the chemical structures of the studied materials. However, SEM observation showed newly-created wrinkles and micro-holes on treated PVC surfaces, and micropores on ABS surfaces. These UV-induced morphological changes on PVC and ABS surfaces increased the surface area which can promote the mechanical interlocking with the adhesive. This explains the improvement of their adhesion strength. Implications of the current study for the processing of strongly bonded polymeric joints are discussed. Wetting ; Materials science ; Contact angle ; Adhesion ; Composite material ; Adhesive ; Natural rubber ; Polyvinyl chloride ; Polymer ; Surface energy ; Fourier transform infrared spectroscopy ; Surface modification ; Ozone ; Chemical engineering ; Chemistry ; Organic chemistry Surface Modification and Superhydrophobicity ; Polymer crystallization and properties ; Polymer Nanocomposite Synthesis and Irradiation
Authors: Stefanos Papanikolaou | Michail Tzimas | Andrew Reid | Stephen A. Langer
Source: Physical review. E (article, 2019-05-16)
Field: Materials Science — Materials Chemistry

Spatial strain correlations, machine learning, and deformation history in crystal plasticity Systems far from equilibrium respond to probes in a history-dependent manner. The prediction of the system response depends on either knowing the details of that history or being able to characterize all the current system properties. In crystal plasticity, various processing routes contribute to a history dependence that may manifest itself through complex microstructural deformation features with large strain gradients. However, the complete spatial strain correlations may provide further predictive information. In this paper, we demonstrate an explicit example where spatial strain correlations can be used in a statistical manner to infer and classify prior deformation history at various strain levels. The statistical inference is provided by machine-learning techniques. As source data, we consider uniaxially compressed crystalline thin films generated by two dimensional discrete dislocation plasticity simulations, after prior compression at various levels. Crystalline thin films at the nanoscale demonstrate yield-strength size effects with very noisy mechanical responses that produce a serious challenge to learning techniques. We discuss the influence of size effects and structural uncertainty to the ability of our approach to distinguish different plasticity regimes. Plasticity ; Deformation (meteorology) ; Crystal plasticity ; Materials science ; Compression (physics) ; Artificial intelligence ; Inference ; Strain (injury) ; Dislocation ; Computer science ; Machine learning ; Statistical physics ; Physics ; Composite material ; Biology Microstructure and mechanical properties ; Metal and Thin Film Mechanics ; Hydrogen embrittlement and corrosion behaviors in metals
Authors: Sungwook Hong | Ken‐ichi Nomura | Aravind Krishnamoorthy | Pankaj Rajak | Chunyang Sheng | Rajiv K. Kalia | Aiichiro Nakano | Priya Vashishta
Source: The Journal of Physical Chemistry Letters (article, 2019-05-03)
Field: Materials Science — Materials Chemistry

Defect Healing in Layered Materials: A Machine Learning-Assisted Characterization of MoS<sub>2</sub> Crystal Phases Monolayer MoS<sub>2</sub> is an outstanding candidate for a next-generation semiconducting material because of its exceptional physical, chemical, and mechanical properties. To make this promising layered material applicable to nanostructured electronic applications, synthesis of a highly crystalline MoS<sub>2</sub> monolayer is vitally important. Among different types of synthesis methods, chemical vapor deposition (CVD) is the most practical way to synthesize few- or mono-layer MoS<sub>2</sub> on the target substrate owing to its simplicity and scalability. However, synthesis of a highly crystalline MoS<sub>2</sub> layer remains elusive. This is because of the number of grains and defects unavoidably generated during CVD synthesis. Here, we perform multimillion-atom reactive molecular dynamics (RMD) simulations to identify an origin of the grain growth, migration, and defect healing process on a CVD-grown MoS<sub>2</sub> monolayer. RMD results reveal that grain boundaries could be successfully repaired by multiple heat treatments. Our work proposes a new way of controlling the grain growth and migration on a CVD-grown MoS<sub>2</sub> monolayer. Monolayer ; Materials science ; Chemical vapor deposition ; Grain boundary ; Substrate (aquarium) ; Nanotechnology ; Characterization (materials science) ; Layer (electronics) ; Crystal (programming language) ; Chemical engineering ; Composite material ; Computer science ; Microstructure 2D Materials and Applications ; MXene and MAX Phase Materials ; Advanced Photocatalysis Techniques
Authors: Carlos H. Borca | Brandon W. Bakr | Lori A. Burns | C. David Sherrill
Source: The Journal of Chemical Physics (article, 2019-10-08)
Field: Materials Science — Materials Chemistry

CrystaLattE: Automated computation of lattice energies of organic crystals exploiting the many-body expansion to achieve dual-level parallelism We present an algorithm to compute the lattice energies of molecular crystals based on the many-body cluster expansion. The required computations on dimers, trimers, etc., within the crystal are independent of each other, leading to a naturally parallel approach. The algorithm exploits the long-range three-dimensional periodic order of crystals to automatically detect and avoid redundant or unnecessary computations. For this purpose, Coulomb-matrix descriptors from machine learning applications are found to be efficient in determining whether two N-mers are identical. The algorithm is implemented as an open-source Python program, CrystaLattE, that uses some of the features of the Quantum Chemistry Common Driver and Databases library. CrystaLattE is initially interfaced with the quantum chemistry package Psi4. With CrystaLattE, we have applied the fast, dispersion-corrected Hartree-Fock method HF-3c to the lattice energy of crystalline benzene. Including all 73 symmetry-unique dimers and 7130 symmetry-unique trimers that can be formed from molecules within a 15 Å cutoff from a central reference monomer, HF-3c plus an Axilrod-Teller-Muto estimate of three-body dispersion exhibits an error of only -1.0 kJ mol<sup>-1</sup> vs the estimated 0 K experimental lattice energy of -55.3 ± 2.2 kJ mol<sup>-1</sup>. The convergence of the HF-3c two- and three-body contributions to the lattice energy as a function of intermonomer distance is examined. Lattice energy ; Reciprocal lattice ; Computation ; Lattice (music) ; Crystal structure ; Coulomb ; Quantum chemistry ; Physics ; Chemistry ; Computer science ; Molecular physics ; Computational chemistry ; Algorithm ; Statistical physics ; Materials science ; Crystallography ; Quantum mechanics ; Diffraction Machine Learning in Materials Science ; Crystallography and molecular interactions ; Advanced Chemical Physics Studies
Authors: Xin Xu | Qianshi Wei | Huaping Li | Yuzhang Wang | Yuguo Chen | Ying Jiang
Source: Physical review. E (article, 2019-04-22)
Field: Materials Science — Materials Chemistry

Recognition of polymer configurations by unsupervised learning Unsupervised learning as an important branch of machine learning is commonly adopted to discover patterns, with the purpose of conducting data clustering without being labeled in advance. In this study, we elucidate the striking ability of unsupervised learning techniques in exploring the phase transitions of polymer configurations. In order to extract the low-dimensional representation of polymer configurations, principal component analysis and diffusion map are applied to distinguish the coiled state and collapsed states and further detect the delicate distinction among collapsed states, respectively. These dimensionality reduction techniques not only identify the distinct states in the feature space, but also offer significant insights to understand the relation between salient features and order parameters in physics. In addition, a hybrid neural network scheme combining the supervised learning and unsupervised learning is utilized to precisely detect the critical point of phase transition between polymer configurations. Our study demonstrates a promising strategy based on the unsupervised learning, particularly in the exploration of phase transition in polymeric systems. Unsupervised learning ; Artificial intelligence ; Cluster analysis ; Dimensionality reduction ; Curse of dimensionality ; Computer science ; Pattern recognition (psychology) ; Competitive learning ; Feature learning ; Artificial neural network ; Representation (politics) ; Machine learning ; Salient ; Principal component analysis ; Feature (linguistics) Machine Learning in Materials Science ; Protein Structure and Dynamics ; Computational Drug Discovery Methods