jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Carlos Cuadrado‐Collados | Georges Mouchaham | Luke Daemen | Yongqiang Cheng | Anibal J. Ramirez‐Cuesta | Himanshu Aggarwal | Alexander Missyul | Mohamed Eddaoudi | Youssef Belmabkhout | Joaquín Silvestre‐Albero
Source: Journal of the American Chemical Society (article, 2020-07-11)
Field: Chemistry — Inorganic Chemistry

Quest for an Optimal Methane Hydrate Formation in the Pores of Hydrolytically Stable Metal–Organic Frameworks Porous metal-organic frameworks (MOFs) capable of storing a relatively high amount of dry methane (CH<sub>4</sub>) in the adsorbed phase are largely explored; however, solid CH<sub>4</sub> storage in confined pores of MOFs in the form of hydrates is yet to be discovered. Here we report a rational approach to form CH<sub>4</sub> hydrates by taking advantage of the optimal pore confinement in relatively narrow cavities of hydrolytically stable MOFs. Unprecedentedly, we were able to isolate methane hydrate (MH) nanocrystals with an sI structure encapsulated inside MOF pores with an optimal cavity dimension. It was found that confined nanocrystals require cavities slightly larger than the unit cell crystal size of MHs (1.2 nm), as exemplified in the experimental case study performed on Cr-<b>soc</b>-MOF-1 vs smaller cavities of Y-<b>shp</b>-MOF-5. Under these conditions, the excess amount of methane stored in the pores of Cr-<b>soc</b>-MOF-1 in the form of MH was found to be ≈50% larger than the corresponding dry adsorbed amount at 10 MPa. More importantly, the pressure gradient driving the CH<sub>4</sub> storage/delivery process could be drastically reduced compared to the conventional CH<sub>4</sub>-adsorbed phase storage on the dry Cr-<b>soc</b>-MOF-1 (≤3 MPa vs 10 MPa). Chemistry ; Methane ; Hydrate ; Metal-organic framework ; Nanocrystal ; Adsorption ; Porosity ; Chemical engineering ; Clathrate hydrate ; Phase (matter) ; Crystal (programming language) ; Metal ; Nanotechnology ; Organic chemistry ; Materials science Metal-Organic Frameworks: Synthesis and Applications ; Methane Hydrates and Related Phenomena ; Hydrocarbon exploration and reservoir analysis
Authors: Yunjian Wu | Xiaoxing Zhang | Ankit Negi | Jixiong He | Guoxiong Hu | Shuangshuang Tian | Jùn Líu
Source: Polymers (article, 2020-02-12)
Field: Materials Science — Materials Chemistry

Synergistic Effects of Boron Nitride (BN) Nanosheets and Silver (Ag) Nanoparticles on Thermal Conductivity and Electrical Properties of Epoxy Nanocomposites Polymer composites, with both high thermal conductivity and high electrical insulation strength, are desirable for power equipment and electronic devices, to sustain increasingly high power density and heat flux. However, conventional methods to synthesize polymer composites with high thermal conductivity often degrade their insulation strength, or cause a significant increase in dielectric properties. In this work, we demonstrate epoxy nanocomposites embedded with silver nanoparticles (AgNPs), and modified boron nitride nanosheets (BNNSs), which have high thermal conductivity, high insulation strength, low permittivity, and low dielectric loss. Compared with neat epoxy, the composite with 25 vol% of binary nanofillers has a significant enhancement (~10x) in thermal conductivity, which is twice of that filled with BNNSs only (~5x), owing to the continuous heat transfer path among BNNSs enabled by AgNPs. An increase in the breakdown voltage is observed, which is attributed to BNNSs-restricted formation of AgNPs conducting channels that result in a lengthening of the breakdown path. Moreover, the effects of nanofillers on dielectric properties, and thermal simulated current of nanocomposites, are discussed. Boron nitride ; Materials science ; Epoxy ; Composite material ; Thermal conductivity ; Nanocomposite ; Dielectric ; Dielectric strength ; Polymer nanocomposite ; Nanoparticle ; Dielectric loss ; Boron ; Nanotechnology ; Optoelectronics ; Chemistry High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Thermal properties of materials
Authors: Lei Ge | Hao Yuan | Yuxiang Min | Li Li | Shiqian Chen | Lai Xu | William A. Goddard
Source: The Journal of Physical Chemistry Letters (article, 2020-01-11)
Field: Materials Science — Materials Chemistry

Predicted Optimal Bifunctional Electrocatalysts for the Hydrogen Evolution Reaction and the Oxygen Evolution Reaction Using Chalcogenide Heterostructures Based on Machine Learning Analysis of in Silico Quantum Mechanics Based High Throughput Screening Two-dimensional van der Waals heterostructure materials, particularly transition metal dichalcogenides (TMDC), have proved to be excellent photoabsorbers for solar radiation, but performance for such electrocatalysis processes as water splitting to form H<sub>2</sub> and O<sub>2</sub> is not adequate. We propose that dramatically improved performance may be achieved by combining two independent TMDC while optimizing such descriptors as rotational angle, bond length, distance between layers, and the ratio of the bandgaps of two component materials. In this paper we apply the least absolute shrinkage and selection operator (LASSO) process of artificial intelligence incorporating these descriptors together with quantum mechanics (density functional theory) to predict novel structures with predicted superior performance. Our predicted best system is MoTe<sub>2</sub>/WTe<sub>2</sub> with a rotation of 300°, which is predicted to have an overpotential of 0.03 V for HER and 0.17 V for OER, dramatically improved over current electrocatalysts for water splitting. Overpotential ; Oxygen evolution ; Water splitting ; van der Waals force ; Chalcogenide ; Materials science ; Heterojunction ; Density functional theory ; Electrocatalyst ; Nanotechnology ; Photocatalysis ; Physical chemistry ; Physics ; Chemistry ; Quantum mechanics ; Optoelectronics ; Catalysis 2D Materials and Applications ; Advanced Photocatalysis Techniques ; Machine Learning in Materials Science
Authors: Hieu A. Doan | Garvit Agarwal | Hai Qian | Michael J. Counihan | Joaquín Rodríguez‐López | Jeffrey S. Moore | Rajeev S. Assary
Source: Chemistry of Materials (article, 2020-05-28)
Field: Materials Science — Materials Chemistry

Quantum Chemistry-Informed Active Learning to Accelerate the Design and Discovery of Sustainable Energy Storage Materials We employed density functional theory (DFT) to compute oxidation potentials of 1400 homobenzylic ether molecules to search for the ideal sustainable redoxmer design. The generated data were used to construct an active learning model based on Bayesian optimization (BO) that targets candidates with desired oxidation potentials utilizing only a minimal number of DFT calculations. The active learning model demonstrated not only significant efficiency improvement over the random selection approach but also robust capability in identifying desired candidates in an untested set of 112 000 homobenzylic ether molecules. Our findings highlight the efficacy of quantum chemistry-informed active learning to accelerate the discovery of materials with desired properties from a vast chemical space. Chemical space ; Density functional theory ; Computer science ; Molecule ; Active learning (machine learning) ; Ideal (ethics) ; Set (abstract data type) ; Quantum chemical ; Quantum chemistry ; Nanotechnology ; Drug discovery ; Chemistry ; Materials science ; Biochemical engineering ; Computational chemistry ; Artificial intelligence ; Organic chemistry ; Engineering Machine Learning in Materials Science ; Advanced battery technologies research ; Electrocatalysts for Energy Conversion
Authors: Ludwig L. Bengel | Benjamin Aberle | Alexander‐N. Egler‐Kemmerer | Samuel Kienzle | Bernhard Hauer | Stephan C. Hammer
Source: Angewandte Chemie International Edition (article, 2020-12-11)
Field: Chemistry — Organic Chemistry

Engineered Enzymes Enable Selective <i>N</i>‐Alkylation of Pyrazoles With Simple Haloalkanes Selective alkylation of pyrazoles could solve a challenge in chemistry and streamline synthesis of important molecules. Here we report catalyst-controlled pyrazole alkylation by a cyclic two-enzyme cascade. In this enzymatic system, a promiscuous enzyme uses haloalkanes as precursors to generate non-natural analogs of the common cosubstrate S-adenosyl-l-methionine. A second engineered enzyme transfers the alkyl group in highly selective C-N bond formations to the pyrazole substrate. The cosubstrate is recycled and only used in catalytic amounts. Key is a computational enzyme-library design tool that converted a promiscuous methyltransferase into a small enzyme family of pyrazole-alkylating enzymes in one round of mutagenesis and screening. With this enzymatic system, pyrazole alkylation (methylation, ethylation, propylation) was achieved with unprecedented regioselectivity (>99 %), regiodivergence, and in a first example on preparative scale. Pyrazole ; Alkylation ; Chemistry ; Combinatorial chemistry ; Enzyme ; Regioselectivity ; Biocatalysis ; Cofactor ; Substrate (aquarium) ; Stereochemistry ; Catalysis ; Organic chemistry ; Reaction mechanism ; Biology Click Chemistry and Applications ; Catalytic C–H Functionalization Methods ; Sulfur-Based Synthesis Techniques
Authors: Ibrahim Dubdub | Mohammed Al‐Yaari
Source: Materials (article, 2020-10-31)
Field: Materials Science — Polymers and Plastics

Pyrolysis of Mixed Plastic Waste: I. Kinetic Study Plastic wastes have become one of the biggest global environmental issues and thus recycling such massive quantities is targeted. Low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS) are considered among the main types of plastic wastes. Since pyrolysis is one of the most promising recycling techniques, this work aims to build knowledge on the co-pyrolysis of mixed polymers using two model-fitting (Criado and Coats-Redfern) methods. Seventeen co-pyrolysis tests using a thermogravimetric analyzer (TGA) at 60 K/min for different mixed compositions of LDPE, HDPE, PP, and PS were conducted. It was observed that the pyrolysis of the pure polymer samples occurs at different temperature ranges in the following order: PS < PP < LDPE < HDPE. However, compared to pure polymer samples, the co-pyrolysis of all-polymer mixtures was delayed. In addition, the synergistic effect on the co-pyrolysis of polymer blends was reported. The Master plot of the Criado model was used to determine the most suitable reaction mechanism. Then, the Coats-Redfern model was used to efficiently obtain the kinetic parameters (R<sup>2</sup> ≥ 97.83%) and the obtained values of the activation energy of different polymer blends were ranging from 104 to 260 kJ/mol. Furthermore, the most controlling reaction mechanisms were in the following orders: First order reaction (F1), Contracting sphere (R3), and then Contracting cylinder (R2). High-density polyethylene ; Low-density polyethylene ; Pyrolysis ; Polyethylene ; Materials science ; Polypropylene ; Polystyrene ; Polymer ; Thermogravimetric analysis ; Plastic waste ; Chemical engineering ; Order of reaction ; Composite material ; Polymer chemistry ; Kinetics ; Waste management ; Reaction rate constant Polymer crystallization and properties ; Microplastics and Plastic Pollution ; Recycling and Waste Management Techniques
Authors: Wenhan Zhou | Shengli Zhang | Shiying Guo | Yangyang Wang | Jing Lü | Xing Ming | Zhi Li | Hengze Qu | Haibo Zeng
Source: Physical Review Applied (article, 2020-04-27)
Field: Materials Science — Materials Chemistry

Designing sub-10-nm Metal-Oxide-Semiconductor Field-Effect Transistors via Ballistic Transport and Disparate Effective Mass: The Case of Two-Dimensional <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mrow><mml:mi>Bi</mml:mi><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:math> In the post-Moore era, improving energy efficiency is an urgent requirement for microelectronics moving towards the Internet of Things, artificial intelligence, and 5G. In particular, two-dimensional (2D) materials with natural passivation, gate electrostatics, and high mobility have attracted significant attention for integrated circuits in the race towards next-generation field-effect transistors (FETs). Here, by coupling first-principles and nonequilibrium-Green's-function approaches, we obtain a physical understanding of the ballistic transport properties of a V-V binary bismuth nitride ($\mathrm{Bi}\mathrm{N}$) material. Promisingly, monolayer $\mathrm{Bi}\mathrm{N}$ has sharp conduction-band and flat valence-band edges, which exhibit disparate effective masses. Simulated sub-10-nm monolayer $\mathrm{Bi}\mathrm{N}$ transistors show potential device performance and fulfill the high-performance and low-power requirements of the goals of the International Technology Roadmap for Semiconductors 2028 with their optimal parameters. Furthermore, by comprehensively analyzing the effective mass, density of states, on-state current, subthreshold swing, etc., we show that materials whose band dispersions have an extreme character have advantages for transistors. Also, benchmarking of the energy-delay product confirms that $\mathrm{Bi}\mathrm{N}$ FETs possess sufficient competitiveness against other 2D FETs. We believe that this could be a guide for designing potential channel materials for next-generation FETs. Materials science ; Transistor ; Microelectronics ; Effective mass (spring–mass system) ; Field-effect transistor ; Semiconductor ; CMOS ; Ambipolar diffusion ; Condensed matter physics ; Nanotechnology ; Physics ; Engineering physics ; Optoelectronics ; Electron ; Quantum mechanics ; Voltage 2D Materials and Applications ; MXene and MAX Phase Materials ; Graphene research and applications
Authors: George Yaw Obeng | Derrick Yeboah Amoah | Richard Opoku | Charles K.K. Sekyere | Eunice Akyereko Adjei | Ebenezer Mensah
Source: Energies (article, 2020-05-01)
Field: Chemistry — Inorganic Chemistry

Coconut Wastes as Bioresource for Sustainable Energy: Quantifying Wastes, Calorific Values and Emissions in Ghana Coconut husks with the shells attached are potential bioenergy resources for fuel-constrained communities in Ghana. In spite of their energy potential, coconut husks and shells are thrown away or burned raw resulting in poor sanitation and environmental pollution. This study focuses on quantifying the waste proportions, calorific values and pollutant emissions from the burning of raw uncharred and charred coconut wastes in Ghana. Fifty fresh coconuts were randomly sampled, fresh coconut waste samples were sun-dried up to 18 days, and a top-lit updraft biochar unit was used to produce biochar for the study. The heat contents of the coconut waste samples and emissions were determined. From the results, 62–65% of the whole coconut fruit can be generated as wastes. The calorific value of charred coconut wastes was 42% higher than the uncharred coconut wastes. PM2.5 and CO emissions were higher than the WHO 24 h air quality guidelines (AQG) value at 25 °C, 1 atmosphere, but the CO concentrations met the WHO standards based on exposure time of 15 min to 8 h. Thus, to effectively utilise coconut wastes as sustainable bioresource-based fuel in Ghana, there is the need to switch from open burning to biocharing in a controlled system to maximise the calorific value and minimise smoke emissions. Heat of combustion ; Husk ; Environmental science ; Biochar ; Waste management ; Raw material ; Bioenergy ; Pollutant ; Pulp and paper industry ; Briquette ; Combustion ; Biofuel ; Environmental engineering ; Chemistry ; Engineering ; Botany ; Pyrolysis ; Biology Coconut Research and Applications ; Energy and Environment Impacts ; Biodiesel Production and Applications
Authors: Barry M. Trost | Zhijun Zuo | Johnathan E. Schultz
Source: Chemistry - A European Journal (review, 2020-07-24)
Field: Chemistry — Organic Chemistry

Transition‐Metal‐Catalyzed Cycloaddition Reactions to Access Seven‐Membered Rings The efficient and selective synthesis of functionalized seven-membered rings remains an important pursuit within synthetic organic chemistry, as this motif appears in numerous drug-like molecules and natural products. Use of cycloaddition reactions remains an attractive approach for their construction within the perspective of atom and step economy. Additionally, the ability to combine multiple components in a single reaction has the potential to allow for efficient combinatorial strategies of diversity-oriented synthesis. The inherent entropic penalty associated with achieving these transformations has impressively been overcome with development of catalysis, whereby the reaction components can be pre-organized through activation by transition-metal-catalysis. The fine-tuning of metal/ligand combinations as well as reaction conditions allows for achieving chemo-, regio-, diastereo- and enantioselectivity in these transformations. Herein, we discuss recent advances in transition-metal-catalyzed construction of seven-membered rings via combination of 2-4 components mediated by a variety of metals. An emphasis is placed on the mechanistic aspects of these transformations to both illustrate the state of the science and to highlight the unique application of novel processes of transition-metals in these transformations. Cycloaddition ; Catalysis ; Transition metal ; Chemistry ; Transition (genetics) ; Organic chemistry Catalytic Alkyne Reactions ; Catalytic C–H Functionalization Methods ; Cyclopropane Reaction Mechanisms
Authors: Tae-Ha Gu | Nam Hee Kwon | Kang-Gyu Lee | Xiaoyan Jin | Seong‐Ju Hwang
Source: Coordination Chemistry Reviews (article, 2020-07-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

2D inorganic nanosheets as versatile building blocks for hybrid electrode materials for supercapacitor Supercapacitor ; Nanotechnology ; Electrode ; Metal hydroxide ; Hybrid material ; Chemistry ; Stacking ; Electrochemistry ; Oxide ; Materials science Supercapacitor Materials and Fabrication ; MXene and MAX Phase Materials ; Advanced battery technologies research
Authors: James Lefley | Christopher Waldron | C. Remzi Becer
Source: Polymer Chemistry (article, 2020-01-01)
Field: Chemistry — Organic Chemistry

Macromolecular design and preparation of polymersomes From drug delivery to nanoreactors and protocells, polymersomes have gained considerable interest from researchers due to their novel applications. Polymersome ; Macromolecule ; Chemistry ; Nanotechnology ; Materials science ; Copolymer ; Biochemistry ; Organic chemistry ; Polymer Advanced Polymer Synthesis and Characterization ; Innovative Microfluidic and Catalytic Techniques Innovation ; Microfluidic and Capillary Electrophoresis Applications
Authors: Shi‐Yong Zhang | Xia Shu | Ying Zeng | Qing‐Yan Liu | Zi‐Yi Du | Chun‐Ting He | Wei‐Xiong Zhang | Xiao‐Ming Chen
Source: Nature Communications (article, 2020-06-02)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Molecule-based nonlinear optical switch with highly tunable on-off temperature using a dual solid solution approach Nonlinear optical switches that reversibly convert between on/off states by thermal stimuli are promising for applications in the fields of photoelectronics and photonics. Currently one main drawback for practical application lies in the control of their switch temperature, especially for the temperature range near room temperature. By mixed melting treatment, here we describe an alloy-like nonlinear optical switch with tunable switch temperature via a dual solid solution approach within the coordination polymer system. We initially prepare a coordination polymer (i-PrNHMe<sub>2</sub>)[Cd(SCN)<sub>3</sub>], which functions as a high-contrast thermoresponsive nonlinear optical switch originating from a phase transition at around 328 K. Furthermore, by taking advantage of a synergistic dual solid solution effect, the melt mixing of it with its analogue (MeNHEt<sub>2</sub>)[Cd(SCN)<sub>3</sub>], which features an unequal anionic chain templated by an isomeric ammonium, can afford coordination polymer solid solutions with switch temperatures that are tunable in a range of 273-328 K merely by varying the component ratio. Optical switch ; Photonics ; Materials science ; Polymer ; Nonlinear optical ; Dual (grammatical number) ; Nonlinear system ; Optoelectronics ; Solid solution ; Molecule ; Nonlinear optics ; Phase (matter) ; Chemical physics ; Chemistry ; Physics ; Organic chemistry Nonlinear Optical Materials Research ; Organic and Molecular Conductors Research ; Crystal Structures and Properties
Authors: Edgar Fuentes | Marieke Gerth | José Augusto Berrocal | Carlo Matera | Pau Gorostiza | Ilja K. Voets | Sílvia Pujals | Lorenzo Albertazzi
Source: Journal of the American Chemical Society (article, 2020-05-12)
Field: Materials Science — Biomaterials

An Azobenzene-Based Single-Component Supramolecular Polymer Responsive to Multiple Stimuli in Water One of the most appealing features of supramolecular assemblies is their ability to respond to external stimuli due to their noncovalent nature. This provides the opportunity to gain control over their size, morphology, and chemical properties and is key toward some of their applications. However, the design of supramolecular systems able to respond to multiple stimuli in a controlled fashion is still challenging. Here we report the synthesis and characterization of a novel discotic molecule, which self-assembles in water into a single-component supramolecular polymer that responds to multiple independent stimuli. The building block of such an assembly is a <i>C</i><sub>3</sub>-symmetric monomer, consisting of a benzene-1,3,5-tricarboxamide core conjugated to a series of natural and non-natural functional amino acids. This design allows the use of rapid and efficient solid-phase synthesis methods and the modular implementation of different functionalities. The discotic monomer incorporates a hydrophobic azobenzene moiety, an octaethylene glycol chain, and a C-terminal lysine. Each of these blocks was chosen for two reasons: to drive the self-assembly in water by a combination of H-bonding and hydrophobicity and to impart specific responsiveness. With a combination of microscopy and spectroscopy techniques, we demonstrate self-assembly in water and responsiveness to temperature, light, pH, and ionic strength. This work shows the potential to integrate independent mechanisms for controlling self-assembly in a single-component supramolecular polymer by the rational monomer design and paves the way toward the use of multiresponsive systems in water. Supramolecular chemistry ; Chemistry ; Azobenzene ; Supramolecular polymers ; Moiety ; Polymer ; Monomer ; Self-assembly ; Supramolecular assembly ; Rational design ; Non-covalent interactions ; Combinatorial chemistry ; Molecule ; Nanotechnology ; Organic chemistry ; Hydrogen bond ; Materials science Supramolecular Self-Assembly in Materials ; Photochromic and Fluorescence Chemistry ; Polydiacetylene-based materials and applications