jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Jun Zhou | Yue Zhang | Song Li | Jing Chen
Source: Catalysts (article, 2019-11-11)
Field: Chemistry — Organic Chemistry

Ni/NiO Nanocomposites with Rich Oxygen Vacancies as High-Performance Catalysts for Nitrophenol Hydrogenation Heterogeneous catalysis often involves charge transfer between adsorbed molecules and the surface of catalyst, and thus their activity depends on the surface charge density. The efficiency of charge transfer could be optimized by adjusting the concentration of oxygen vacancies (Ov). In this work, hexagonal Ni(OH)2 nanoparticles were initially synthesized by a hydrothermal process using aluminum powder as the sacrificial agent, and were then converted into 2D Ni/NiO nanocomposites through in situ reduction in hydrogen flow. The oxygen vacancy concentration in the NiO nanosheet could be well-controlled by adjusting the reduction temperature. This resulted in strikingly high activities for hydrogenation of nitrophenol. The Ni/NiO nanocomposite could easily be recovered by a magnetic field for reuse. The present finding is beneficial for producing better hydrogenation catalysts and paves the way for the design of highly efficient catalysts. Materials science ; Catalysis ; Non-blocking I/O ; Nanosheet ; Nanocomposite ; Chemical engineering ; Oxygen ; Nanotechnology ; Chemistry ; Organic chemistry Nanomaterials for catalytic reactions ; Copper-based nanomaterials and applications ; MXene and MAX Phase Materials
Authors: Yujie Ke | Shunsheng Ye | Peng Hu | Hui Jiang | Shancheng Wang | Bai Yang | Junhu Zhang | Yi Long
Source: Materials Horizons (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Unpacking the toolbox of two-dimensional nanostructures derived from nanosphere templates This review summarizes the advances in 2D nanostructures derived from nanosphere templates, from fabrication and properties to applications. Template ; Unpacking ; Nanosphere lithography ; Nanostructure ; Nanotechnology ; Toolbox ; Fabrication ; Materials science ; Computer science ZnO doping and properties ; Nanowire Synthesis and Applications ; Gas Sensing Nanomaterials and Sensors
Authors: Qiankun Wang | Valentín Diez‐Cabanes | Simone Dell’Elce | Andrea Liscio | Björn Kobin | Hong Li | Jean‐Luc Brédas | Stefan Hecht | Vincenzo Palermo | Emil List | Jérôme Cornil | Norbert Koch | Giovanni Ligorio
Source: ACS Applied Nano Materials (article, 2019-01-23)
Field: Materials Science — Materials Chemistry

Dynamically Switching the Electronic and Electrostatic Properties of Indium–Tin Oxide Electrodes with Photochromic Monolayers: Toward Photoswitchable Optoelectronic Devices The chemical modification of electrodes with organic materials is a common approach to tuning the electronic and electrostatic landscapes between interlayers in optoelectronic devices, thus facilitating charge injection at the electrode/semiconductor interfaces and improving their performance. The use of photochromic molecules for surface modification allows a dynamic control of the electronic and electrostatic properties of the electrode and thereby enables additional functionalities in such devices. Here, we show that the electronic properties of a transparent indium–tin oxide (ITO) electrode are reversibly and dynamically modified by depositing organic photochromic switches (diarylethenes) in the form of self-assembled monolayers (SAMs). By combining a range of surface characterization and density functional theory calculations, we present a detailed picture of the SAM binding to ITO, the packing density of molecules, their orientation, and work function modification of the ITO surface due to SAM deposition. Upon illumination with UV and green light, we observe a reversible shift of the frontier occupied levels by 0.7 eV and concomitantly a reversible work function change of ca. 60 meV. Our results prove the viability of dynamic switching of the electronic properties of the electrode with external light stimuli upon modification with a monolayer of photochromic molecules, which could be used to fabricate ITO-based photoswitchable optoelectronic devices. Photochromism ; Indium tin oxide ; Materials science ; Electrode ; Monolayer ; Optoelectronics ; Work function ; Self-assembled monolayer ; Density functional theory ; Surface modification ; Nanotechnology ; Thin film ; Chemistry ; Layer (electronics) Photochromic and Fluorescence Chemistry ; Advanced Memory and Neural Computing ; Molecular Junctions and Nanostructures
Authors: Uwe Rosenthal
Source: ChemistryOpen (review, 2019-07-23)
Field: Chemistry — Organic Chemistry

Advantages of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes as Metallocene Sources Towards Other Synthetically used Systems Abstract Active species for synthetic and catalytic applications are formed from well defined complexes or mixtures of compounds. For group 4 metallocenes, three pathways for the formation of the reactive complex fragment [Cp′ 2 M] are known: (i) reductive mixtures and well defined complexes which are able to form the metallocene fragments either by (ii) addition or (iii) substitution reactions. In this account for each of theses systems (i)–(iii) a prominent example will be discussed in detail, (i) the Negishi reagent Cp 2 ZrCl 2 /n‐BuLi, (ii) bis(η 5 : η 1 ‐pentafulvene) complexes and (iii) metallocene bis(trimethylsilyl)acetylene complexes, to show the advantages and the disadvantages for each of these methods for synthetic applications. This account summarizes some main advantages of group 4 metallocene bis(trimethylsilyl)acetylene complexes as metallocene generating agents over other synthetically used systems. For each of the special purposes, all described systems have advantages as well as disadvantages. The aim of this overview is to help synthetic chemists in selecting the most effective system on the basis of [Cp′ 2 M] (M=Ti, Zr) for synthetic or catalytic puposes. Metallocene ; Trimethylsilyl ; Acetylene ; Group (periodic table) ; Materials science ; Polymer science ; Chemistry ; Organic chemistry ; Polymerization Organometallic Complex Synthesis and Catalysis ; Synthesis and characterization of novel inorganic/organometallic compounds ; Organoboron and organosilicon chemistry
Authors: Ryan Poling-Skutvik | Ali H. Slim | Suresh Narayanan | Jacinta C. Conrad | Ramanan Krishnamoorti
Source: ACS Macro Letters (article, 2019-07-16)
Field: Materials Science — Polymers and Plastics

Soft Interactions Modify the Diffusive Dynamics of Polymer-Grafted Nanoparticles in Solutions of Free Polymer We examine the dynamics of silica particles grafted with high molecular weight polystyrene suspended in semidilute solutions of chemically similar linear polymer using X-ray photon correlation spectroscopy. The particle dynamics decouple from the bulk viscosity despite their large hydrodynamic size and instead experience an effective viscosity that depends on the molecular weight of the free polymer chains. Unlike for hard-sphere nanoparticles in semidilute polymer solutions, the diffusivities of the polymer-grafted nanoparticles do not collapse onto a master curve solely as a function of normalized length scales. Instead, the diffusivities can be collapsed across two orders of magnitude in free polymer molecular weight and concentration and one order of magnitude in grafted molecular weight by incorporating the ratio of free to grafted polymer molecular weights. These results suggest that the soft interaction potential between polymer-grafted nanoparticles and free polymer allows polymer-grafted nanoparticles to diffuse faster than predicted based on bulk rheology and modifies the coupling between grafted particle dynamics and the relaxations of the surrounding free polymer. Polymer ; Rheology ; Molecular dynamics ; Polystyrene ; Nanoparticle ; Viscosity ; Particle (ecology) Polymer Nanocomposites and Properties ; Material Dynamics and Properties ; Electrostatics and Colloid Interactions
Authors: Xianxiao Chen | Yuanyuan Zhou | Jianwen Jin | ‬‬‬‬‬‬Kaveh Farshadfar | Alireza Ariafard | Weidong Rao | Philip Wai Hong Chan
Source: Advanced Synthesis & Catalysis (article, 2019-12-19)
Field: Chemistry — Organic Chemistry

Gold Catalyzed Cyclopropanation/[5+3] Cycloaddition of 1,4,9‐ and 1,4,10‐Allenenynes to Bicyclo[3.3.1]nonane Derivatives Abstract A synthetic method to prepare cycloalkyl‐ and (hetero)aryl‐fused bicyclo[3.3.1]nonane derivatives from gold(I)‐catalyzed cyclopropanation/[5+3] cycloaddition of 1,4,9‐ and 1,4,10‐allenenynes is described. The suggested double cycloisomerization mechanism delineates the first example of a stepwise [5+3] cycloaddition pathway in gold catalysis, a mode of reactivity that is also sparse in organic chemistry. Experimental and Density Functional Theory (DFT) computational studies based on a proposed gold carbenoid species provides insight into this unique selectivity that leads to the assembly of the architecturally challenging bridged carbocyclic motif. magnified image Carbenoid ; Cycloaddition ; Chemistry ; Cyclopropanation ; Nonane ; Bicyclic molecule ; Cycloisomerization ; Catalysis ; Reactivity (psychology) ; Selectivity ; Aryl ; Density functional theory ; Computational chemistry ; Stereochemistry ; Combinatorial chemistry ; Medicinal chemistry ; Organic chemistry ; Rhodium Catalytic Alkyne Reactions ; Cyclopropane Reaction Mechanisms ; Synthetic Organic Chemistry Methods
Authors: JeongEun Yoo | Patrik Schmuki
Source: Journal of The Electrochemical Society (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Critical Factors in the Anodic Formation of Extremely Ordered Titania Nanocavities In the present work, we discuss the formation of a highly ordered form of TiO 2 nanotubes (U-tubes) which are grown by anodizing Ti metal in a concentrated HF/H 3 PO 4 electrolyte. The crucial parameters determining geometry and order of the tubes (such as, temperature, applied voltage, concentration of HF, and anodizing time) are investigated and discussed. Under optimized conditions, not only very high degree of order, but also a perfectly open tube top morphology is obtained. The amorphous titania tubes (cavities) consist of a phosphate rich inner layer and a fluoride rich outer layer. Thermal crystallization of these short amorphous cavities to anatase/rutile at temperatures (>400C) in air leads to partial oxidation of the underneath metal -this and the short length of the tubes, usually around 200 nm, pose challenges for potential photoelectrochemical applications. However, the limited tube length can be overcome by a double anodizing technique. The extremely high order and unique nature of these types of self-ordered tubes allows for unprecedented control and enables various uses of the tubes. Anodizing ; Anatase ; Materials science ; Amorphous solid ; Crystallization ; Electrolyte ; Layer (electronics) ; Rutile ; Titanium ; Chemical engineering ; Tube (container) ; Metal ; Nanotechnology ; Composite material ; Metallurgy ; Crystallography ; Electrode ; Chemistry ; Aluminium Anodic Oxide Films and Nanostructures ; TiO2 Photocatalysis and Solar Cells ; Ga2O3 and related materials
Authors: Dmitry Karpov | Zhen Liu | Anil Kumar | Boris Kiefer | Ross Harder | Turab Lookman | Edwin Fohtung
Source: Physical review. B./Physical review. B (article, 2019-08-22)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Nanoscale topological defects and improper ferroelectric domains in multiferroic barium hexaferrite nanocrystals Multiferroic materials that demonstrate magnetically driven ferroelectricity have fascinating properties such as magnetic (electric) field-controlled ferroelectric (magnetic) response that can be used in transformative applications including fast-writing, power-saving, and nondestructive data storage technologies in next-generation computing devices. However, since multiferroicity is typically observed at low temperatures, it is highly desirable to design multiferroic materials that can operate at room temperature. Here we show that $\mathrm{BaF}{\mathrm{e}}_{12}{\mathrm{O}}_{19}$ is a promising room-temperature multiferroic material, and we unravel in three dimensions (3D) the dynamics of topological defects, strain, and improper ferroelectric domains driven by electric fields in individual $\mathrm{BaF}{\mathrm{e}}_{12}{\mathrm{O}}_{19}$ nanocrystals. Using Bragg coherent diffractive imaging in combination with group-theoretical analysis, first-principles density functional calculations of phonons, and Landau phase-field theory we uncover in 3D the dynamics of topological defects, strain, and improper ferroelectric domains driven by electric fields in individual $\mathrm{BaF}{\mathrm{e}}_{12}{\mathrm{O}}_{19}$ nanocrystals. Our results show that $\mathrm{BaF}{\mathrm{e}}_{12}{\mathrm{O}}_{19}$ is an improper ferroelectric, in contrast to the current paradigm that adheres to the absence of improper ferroelectricity. Moreover, the fine structure of the reconstructed Bragg electron density suggests that $\mathrm{BaF}{\mathrm{e}}_{12}{\mathrm{O}}_{19}$ may be able to harbor novel topological quantum states of matter and a pathway to transform information technologies. Multiferroics ; Ferroelectricity ; Condensed matter physics ; Materials science ; Nanoscopic scale ; Nanocrystal ; Nanotechnology ; Topology (electrical circuits) ; Physics ; Dielectric ; Optoelectronics Multiferroics and related materials ; Ferroelectric and Piezoelectric Materials ; High-pressure geophysics and materials
Authors: Sizhu Yu | Xiaodong Li | Xiaoyan Guo | Zhiren Li | Meishuai Zou
Source: Polymers (article, 2019-07-03)
Field: Materials Science — Polymers and Plastics

Curing and Characteristics of N,N,N′,N′-Tetraepoxypropyl-4,4′-Diaminodiphenylmethane Epoxy Resin-Based Buoyancy Material Buoyancy material is a type of low-density and high-strength composite material which can provide sufficient buoyancy with deep submersibles. A new buoyancy material with N,N,N',N'-tetraepoxypropyl-4,4'-diaminodiphenylmethane epoxy resin (AG-80) and m-xylylenediamine (m-XDA) curing agent as matrix and hollow glass microsphere (HGM) as the filler is prepared. The temperature and time of the curing process were determined by the calculations of thermal analysis kinetics (TAK) through differential scanning calorimetry (DSC) analysis. The results show that the better mass ratio of AG-80 with m-XDA is 100/26. Combined TAK calculations and experimental results lead to the following curing process: pre-curing at 75 °C for 2 h, curing at 90 °C for 2 h, and post-curing at 100 °C for 2 h. The bulk density, compressive strength, and saturated water absorption of AG-80 epoxy resin-based buoyancy material were 0.729 g/cm<sup>3</sup>, 108.78 MPa, and 1.23%, respectively. Moreover, this type of buoyancy material can resist the temperature of 250 °C. Curing (chemistry) ; Materials science ; Epoxy ; Differential scanning calorimetry ; Composite material ; Buoyancy ; Glass microsphere ; Absorption of water ; Microsphere ; Chemical engineering ; Thermodynamics Polymer composites and self-healing ; Polymer Nanocomposites and Properties ; Epoxy Resin Curing Processes
Authors: Zhongyuan Li | Wei-Feng Sun | Hong Zhao
Source: Polymers (article, 2019-12-13)
Field: Materials Science — Materials Chemistry

Significantly Improved Electrical Properties of Photo-Initiated Auxiliary Crosslinking EPDM Used for Cable Termination In order to achieve high quality electrical materials for cable terminations, the crosslinked ethylene-propylene-diene monomer (EPDM) materials, with adequate breakdown strength, appropriately increased conductivity and are developed by employing auxiliary crosslinker and ultraviolet (UV) photoinitiated crosslinking technique. The characteristic cyclic anhydrides with coupled carbonyl groups are utilized as auxiliary crosslinkers to promote crosslinking efficiency and provide polar-groups to EPDM molecules in UV-initiated crosslinking processes, which can be effectively fulfilled in industrial cable production. The results of infrared spectroscopy show that the auxiliary crosslinkers have been successfully grated to EPDM molecules through UV initiation process. The conductivity of EPDM increases after individually utilizing three auxiliary crosslinkers to EPDM at various temperatures of cable operations, by which the highest conductivity has been acquired by grafting <i>N</i>.<i>N</i>-m-phenylene dimaleimide. The first-principles calculations demonstrate that some occupied local electronic-states have been introduced in the band-gap of the EPDM crosslinked by <i>N</i>.<i>N</i>-m-phenylene dimaleimide (EPDM-HAV2), which can be thermally excited from valence band to conduction band at lower temperature or in higher density, leading to augmentation in electrical conductivity. Meanwhile, the breakdown strength achieves a significant improvement in consistency with the theoretical estimation that deeper hole-traps can be introduced by auxiliary-crosslinking modification, and will consequently increase breakdown strength through the trapping mechanism of space charge suppression. in relation to the appropriately increased conductivity, in combination with persistent breakdown strength, the finite element simulations of the electric field distribution in EPDM cable terminations suggest that the effectively homogenized electric field at the root of stress cone will be realized for EPDM-HAV2. The present study offers a fundamental strategy to ameliorate EPDM materials in the application of insulated cable accessories. Materials science ; Composite material High voltage insulation and dielectric phenomena ; Electrical Contact Performance and Analysis ; Electromagnetic wave absorption materials
Authors: Muhammad Majid Hussain | Muhammad Akmal Chaudhary | Abdul Razaq
Source: Energies (article, 2019-09-26)
Field: Materials Science — Materials Chemistry

Mechanism of Saline Deposition and Surface Flashover on High-Voltage Insulators near Shoreline: Mathematical Models and Experimental Validations This paper deals with sea salt transportation and deposition mechanisms and discusses the serious issue of degradation of outdoor insulators resulting from various environmental stresses and severe saline contaminant accumulation near the shoreline. The deterioration rate of outdoor insulators near the shoreline depends on the concentration of saline in the atmosphere, the influence of wind speed on the production of saline water droplets, moisture diffusion and saline penetration on the insulator surface. This paper consists of three parts: first a model of saline transportation and deposition, as well as saline penetration and moisture diffusion on outdoor insulators, is presented; second, dry-band initiation and formation modelling and characterization under various types of contamination distribution are proposed; finally, modelling of dry-band arcing validated by experimental investigation was carried out. The tests were performed on a rectangular surface of silicone rubber specimens (12 cm × 4 cm × 8 cm). The visualization of the dry-band formation and arcing was performed by an infrared camera. The experimental results show that the surface strength and arc length mainly depend upon the leakage distance and contamination distribution. Therefore, the model can be used to investigate insulator flashover near coastal areas and for mitigating saline flashover incidents. Saline water ; Penetration (warfare) ; Insulator (electricity) ; Environmental science ; Materials science ; Deposition (geology) ; Moisture ; Contamination ; Arc flash ; Saline ; Composite material ; Geotechnical engineering ; Geology ; Salinity ; Engineering High voltage insulation and dielectric phenomena ; Thermal Analysis in Power Transmission ; Power Transformer Diagnostics and Insulation
Authors: Jinzhe Zeng | Liqun Cao | Mingyuan Xu | Tong Zhu | John Z. H. Zhang
Source: arXiv (Cornell University) (preprint, 2019-11-27)
Field: Materials Science — Materials Chemistry

Neural Network Based in Silico Simulation of Combustion Reactions Understanding and prediction of the chemical reactions are fundamental demanding in the study of many complex chemical systems. Reactive molecular dynamics (MD) simulation has been widely used for this purpose as it can offer atomic details and can help us better interpret chemical reaction mechanisms. In this study, two reference datasets were constructed and corresponding neural network (NN) potentials were trained based on them. For given large-scale reaction systems, the NN potentials can predict the potential energy and atomic forces of DFT precision, while it is orders of magnitude faster than the conventional DFT calculation. With these two models, reactive MD simulations were performed to explore the combustion mechanisms of hydrogen and methane. Benefit from the high efficiency of the NN model, nanosecond MD trajectories for large-scale systems containing hundreds of atoms were produced and detailed combustion mechanism was obtained. Through further development, the algorithms in this study can be used to explore and discovery reaction mechanisms of many complex reaction systems, such as combustion, synthesis, and heterogeneous catalysis without any predefined reaction coordinates and elementary reaction steps. Combustion ; Molecular dynamics ; Artificial neural network ; Computer science ; Reaction mechanism ; Biological system ; Chemical reaction ; Elementary reaction ; Scale (ratio) ; Reaction dynamics ; Chemistry ; Complex system ; Biochemical engineering ; Computational chemistry ; Catalysis ; Artificial intelligence ; Molecule ; Physical chemistry ; Physics ; Engineering ; Kinetics Machine Learning in Materials Science ; Catalysis and Oxidation Reactions ; Advanced Chemical Physics Studies
Authors: Mojtaba Haghighatlari | Gaurav Vishwakarma | Doaa Altarawy | R. Subramanian | Bhargava Urala Kota | Aditya Sonpal | Srirangaraj Setlur | Johannes Hachmann
Source: ChemRxiv (preprint, 2019-06-26)
Field: Materials Science — Materials Chemistry

ChemML: A Machine Learning and Informatics Program Package for the Analysis, Mining, and Modeling of Chemical and Materials Data &lt;div&gt;&lt;i&gt;ChemML&lt;/i&gt; is an open machine learning and informatics program suite that is designed to support and advance the data-driven research paradigm that is currently emerging in the chemical and materials domain. &lt;i&gt;ChemML&lt;/i&gt; allows its users to perform various data science tasks and execute machine learning workflows that are adapted specifically for the chemical and materials context. Key features are automation, general-purpose utility, versatility, and user-friendliness in order to make the application of modern data science a viable and widely accessible proposition in the broader chemistry and materials community. &lt;i&gt;ChemML&lt;/i&gt; is also designed to facilitate methodological innovation, and it is one of the cornerstones of the software ecosystem for data-driven &lt;i&gt;in silico&lt;/i&gt; research outlined in our recent publication&lt;sup&gt;1&lt;/sup&gt;.&lt;/div&gt; Workflow ; Informatics ; Suite ; Computer science ; Context (archaeology) ; Automation ; Domain (mathematical analysis) ; Data science ; Software engineering ; World Wide Web ; Engineering ; Database Machine Learning in Materials Science ; Computational Drug Discovery Methods ; History and advancements in chemistry