jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Jaejoon Jung | Sang Jun Lee
Source: Journal of Microbiology and Biotechnology (review, 2019-10-28)
Field: Chemistry — Electrochemistry

Biochemical and Biodiversity Insights into Heavy Metal Ion-Responsive Transcription Regulators for Synthetic Biological Heavy Metal Sensors To adapt to environmental changes and to maintain cellular homeostasis, microorganisms adjust the intracellular concentrations of biochemical compounds, including metal ions; these are essential for the catalytic function of many enzymes in cells, but excessive amounts of essential metals and heavy metals cause cellular damage. Metal-responsive transcriptional regulators play pivotal roles in metal uptake, pumping out, sequestration, and oxidation or reduction to a less toxic status via regulating the expression of the detoxification-related genes. The sensory and regulatory functions of the metalloregulators have made them as attractive biological parts for synthetic biology, and the exceptional sensitivity and selectivity of metalloregulators toward metal ions have been used in heavy metal biosensors to cope with prevalent heavy metal contamination. Due to their importance, substantial efforts have been made to characterize heavy metal-responsive transcriptional regulators and to develop heavy metal-sensing biosensors. In this review, we summarize the biochemical data for the two major metalloregulator families, SmtB/ArsR and MerR, to describe their metal-binding sites, specific chelating chemistry, and conformational changes. Based on our understanding of the regulatory mechanisms, previously developed metal biosensors are examined to point out their limitations, such as high background noise and a lack of well-characterized biological parts. We discuss several strategies to improve the functionality of the metal biosensors, such as reducing the background noise and amplifying the output signal. From the perspective of making heavy metal biosensors, we suggest that the characterization of novel metalloregulators and the fabrication of exquisitely designed genetic circuits will be required. Biosensor ; Metal ions in aqueous solution ; Metal ; Riboswitch ; Chemistry ; Nanotechnology ; Heavy metals ; Computational biology ; Biology ; Biophysics ; Gene ; Environmental chemistry ; Biochemistry ; Gene expression ; Materials science Electrochemical Analysis and Applications ; Heavy metals in environment ; Analytical chemistry methods development
Authors: Mohamed Alaasar | Marko Prehm | Sebastian Belau | Nerea Sebastián | Marharyta Kurachkina | Alexey Eremin | Changlong Chen | Feng Liu | Carsten Tschierske
Source: Chemistry - A European Journal (article, 2019-02-14)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Polar Order, Mirror Symmetry Breaking, and Photoswitching of Chirality and Polarity in Functional Bent‐Core Mesogens In recent years, liquid crystals (LCs) responding to light or electrical fields have gained significant importance as multifunctional materials. Herein, two new series of photoswitchable bent-core liquid crystals (BCLCs) derived from 4-cyanoresorcinol as the central core connected to an azobenzene based wing and a phenyl benzoate wing are reported. The self-assembly of these molecules was characterized by differential scanning calorimetry (DSC), polarizing light microscopy (POM), electro-optical, dielectric, second harmonic generation (SHG) studies, and XRD. Depending on the direction of the COO group in the phenyl benzoate wing, core-fluorination, temperature, and the terminal alkyl chain length, cybotactic nematic and lamellar (smectic) LC phases were observed. The coherence length of the ferroelectric fluctuations increases continuously with decreasing temperature and adopts antipolar correlation upon the condensation into superparaelectric states of the paraelectric smectic phases. Finally, long-range polar order develops at distinct phase transitions; first leading to polarization modulated and then to nonmodulated antiferroelectric smectic phases. Conglomerates of chiral domains were observed in the high permittivity ranges of the synclinic tilted paraelectric smectic phases of these achiral molecules, indicating mirror symmetry breaking. Fine-tuning of the molecular structure leads to photoresponsive bent-core (BC)LCs exhibiting a fast and reversible photoinduced change of the mode of the switching between ferroelectric- and antiferroelectric-like as well as a light-induced switching between an achiral and a spontaneous mirror-symmetry-broken LC phase. Liquid crystal ; Ferroelectricity ; Antiferroelectricity ; Materials science ; Dielectric ; Azobenzene ; Chirality (physics) ; Phase (matter) ; Bent molecular geometry ; Crystallography ; Phase transition ; Chemical physics ; Condensed matter physics ; Flexoelectricity ; Molecule ; Symmetry breaking ; Chemistry ; Spontaneous symmetry breaking ; Optoelectronics ; Physics ; Organic chemistry Liquid Crystal Research Advancements ; Photochromic and Fluorescence Chemistry ; Molecular spectroscopy and chirality
Authors: Marc‐André Serrer | Kai F. Kalz | Erisa Saraҫi | Henning Lichtenberg | Jan‐Dierk Grunwaldt
Source: ChemCatChem (article, 2019-08-09)
Field: Materials Science — Materials Chemistry

Role of Iron on the Structure and Stability of Ni<sub>3.2</sub>Fe/Al<sub>2</sub>O<sub>3</sub> during Dynamic CO<sub>2</sub> Methanation for P2X Applications Abstract An energy scenario, mainly based on renewables, requires efficient and flexible Power‐to‐X (P2X) storage technologies, including the methanation of CO 2 . As active Ni 0 surface sites of monometallic nickel‐based catalysts are prone to surface oxidation under hydrogen‐deficient conditions, we investigated iron as “protective” dopant. A combined operando X‐ray absorption spectroscopy and X‐ray diffraction setup with quantitative on‐line product analysis was used to unravel the structure of Ni and Fe in an alloyed Ni−Fe/Al 2 O 3 catalyst during dynamically driven methanation of CO 2 . We observed that Fe protects Ni from oxidation and is itself more dynamic in the oxidation and reduction process. Hence, such “sacrificial” or “protective” dopants added in order to preserve the catalytic activity under dynamic reaction conditions may not only be of high relevance with respect to fine‐tuning of catalysts for future industrial P2X applications but certainly also of general interest. Methanation ; Catalysis ; Dopant ; Nickel ; Materials science ; Hydrogen storage ; Redox ; Hydrogen ; Chemical engineering ; Inorganic chemistry ; Chemistry ; Metallurgy ; Doping ; Organic chemistry Catalytic Processes in Materials Science ; Catalysts for Methane Reforming ; Electrocatalysts for Energy Conversion
Authors: Janio Venturini | Tiago Bender Wermuth | Márcia Corrêa Machado | Sabrina Arcaro | Annelise Kopp Alves | A. D. C. Viegas | Carlos Pérez Bergmann
Source: Journal of the European Ceramic Society (article, 2019-01-23)
Field: Materials Science — Materials Chemistry

The influence of solvent composition in the sol-gel synthesis of cobalt ferrite (CoFe2O4): A route to tuning its magnetic and mechanical properties Materials science ; Pellets ; Cobalt ferrite ; Coercivity ; Ceramic ; Ferrite (magnet) ; Solvent ; Cobalt ; Chemical engineering ; Vickers hardness test ; Composite material ; Metallurgy ; Microstructure ; Organic chemistry Magnetic Properties and Synthesis of Ferrites ; Electromagnetic wave absorption materials ; Multiferroics and related materials
Authors: Li-kun Shi | Jing Ma | Justin C. W. Song
Source: 2D Materials (article, 2019-12-11)
Field: Materials Science — Materials Chemistry

Gate-tunable flat bands in van der Waals patterned dielectric superlattices Abstract Superlattice engineering provides the means to reshape the fabric felt by quasiparticles moving in a material. Here we argue that bandstructure engineering with superlattices can be pushed to the extreme limit by stacking gapped van der Waals (vdW) materials on patterned dielectric substrates. Specifically, we find that high quality vdW patterned dielectric superlattices (PDS) realize a series of robust flat bands that can be directly switched on and off by gate voltage in situ . In contrast to existing superlattice platforms, these flat bands are realized without the need for fine tuning. Instead, the bands become flat as the gate voltage increases in magnitude. The characteristics of PDS flatbands are highly tunable: the type of flatband (single non-degenerate or dirac-cone-like), localization length, and interaction energy are sensitive to the applied gate voltage. As a result, electron-electron interactions in the PDS flatbands can become stronger than both the bandwidth and disorder broadening, providing a setting for correlated behavior such as flatband ferromagnetism. We expect PDS flatbands can be experimentally realized in a range of readily available gapped vdW materials such as monolayer transition metal dichalcogenides, e.g. WSe 2 . Superlattice ; van der Waals force ; Condensed matter physics ; Materials science ; Dielectric ; Monolayer ; Stacking ; Plasmon ; Quasiparticle ; Optoelectronics ; Electron ; Nanotechnology ; Physics ; Superconductivity ; Quantum mechanics 2D Materials and Applications ; Graphene research and applications ; MXene and MAX Phase Materials
Authors: Rui Huang | Kyeounghak Kim | Hyung Jun Kim | Myeong Gon Jang | Jeong Woo Han
Source: ACS Applied Nano Materials (article, 2019-12-05)
Field: Materials Science — Materials Chemistry

Size-Controlled Pd Nanoparticles Loaded on Co<sub>3</sub>O<sub>4</sub> Nanoparticles by Calcination for Enhanced CO Oxidation In accordance with Euro 6 emission standards, exhaust emissions are required to be substantially lowered especially via significant improvement in the efficiency of catalytic oxidation to reduce toxic carbon monoxide (CO). It has been reported that nanoparticles with high surface-to-volume ratio efficiently enhance the catalytic activity by providing additional active sites per unit area. However, the principle underlying this phenomenon is still not clear. To systematically elucidate the effect of metal nanoparticles on catalytic activity, we controlled the size of Pd nanoparticles loaded on Co3O4 by changing the calcination temperature. This approach was used to fine-tune the particle size from 2.5 to 10.6 nm. We found that Pd particle size is a dominant factor that affects the CO oxidation activity; smaller Pd particles yielded better catalytic activity. Three important reaction steps were identified through DFT calculations, based on which a series of temperature-programmed desorption and reduction measurements such as CO-TPD, CO chemisorption, O2-TPD, and CO-TPR were performed. The better abilities of CO desorption and O2 dissociation as well as the easier CO2 formation were found to be responsible for the higher activity of smaller Pd particles. We believe that our findings represent a potential strategy for the development of highly efficient catalysts. Calcination ; Catalysis ; Nanoparticle ; Carbon monoxide ; Chemisorption ; Dissociation (chemistry) ; Particle size ; Desorption ; Chemical engineering ; Materials science ; Inorganic chemistry ; Chemistry ; Nanotechnology ; Physical chemistry ; Adsorption ; Organic chemistry Catalytic Processes in Materials Science ; Catalysis and Oxidation Reactions ; Catalysts for Methane Reforming
Authors: Kun Liu | Feng Xu | Yuan Wang | Meng Qian | Wei Zhao | Yi Zeng | Fuqiang Huang
Source: Energy Technology (article, 2019-09-11)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Boron and Nitrogen Co‐Doped Trimodal‐Porous Wood‐Derived Carbon for Boosting Capacitive Performance Heteroatom doping and a porous structure are two significant factors that improve the capacitance performance of carbon‐based electrodes, but there are often one‐sided considerations between them. Herein, effective B, N co‐doping and trimodal‐porous structure from the carbonization of sustainable natural wood are obtained at the same time. The unique pore structure is coarsely tuned by a modified ZnAc 2 ‐assisted hypersaline route and further fine‐tuned by controlling the doping levels of boron and nitrogen. The high specific surface area of porous carbon up to 1201 m 2 g −1 is coordinated with the trimodal foam‐like nanopores. This carbon‐based material as a supercapacitor electrode can provide not only trimodal‐porous ion transfer highways but also doping‐induced pseudocapacitance. The resulting pore and heteroatom reengineered wood‐derived carbon harvests a remarkable capacitance of 479 F g −1 at 1 A g −1 , among the highest values in reported B, N co‐doped carbon electrodes. The aqueous symmetric supercapacitor exhibits energy density of 18.5 Wh kg −1 and power density of 6.4 kW kg −1 , along with &gt;90% capacitance retention, both in H 2 SO 4 and Li 2 SO 4 electrolyte over 10 000 cycles. Heteroatom ; Supercapacitor ; Materials science ; Pseudocapacitance ; Carbon fibers ; Carbonization ; Capacitance ; Chemical engineering ; Doping ; Electrolyte ; Boron ; Porosity ; Electrode ; Nanotechnology ; Composite material ; Organic chemistry ; Chemistry ; Optoelectronics ; Composite number ; Scanning electron microscope Supercapacitor Materials and Fabrication ; Advancements in Battery Materials ; Advanced Battery Materials and Technologies
Authors: Aline Nonat | Amandine Roux | Maryame Sy | Loı̈c J. Charbonnière
Source: Dalton Transactions (review, 2019-01-01)
Field: Chemistry — Organic Chemistry

2,4-Substituted bispidines as rigid hosts for versatile applications: from κ-opioid receptor to metal coordination Bispidones (3,7-diazabicyclo[3.3.1]nonan-9-one) are bicyclic analogues of the natural antiarrhythmic agent, spartein. They can straightforwardly be obtained from two successive Mannich reactions. Reduction of the ketone gives the corresponding bispidol. Substituted bispidones and bispidols offer a large playground by varying the substituents, the configuration of the carbon atoms in position 2 and 4 as well as the conformation of the bicycle. While chair-boat conformers display a strong affinity for κ-opioid receptors, chair-chair bispidines provide adaptable coordination spheres for transition metal and rare-earth ions. Because of their very rich coordination chemistry, substituted bispidines have emerged in various applications of coordination chemistry, such as catalysis, magnetism and medical imaging. Opioid receptor ; Metal ; Chemistry ; Combinatorial chemistry ; Coordination complex ; Opioid ; Receptor ; Stereochemistry ; Organic chemistry ; Biochemistry Synthesis of β-Lactam Compounds ; Metal complexes synthesis and properties ; Pharmacological Receptor Mechanisms and Effects
Authors: Rajendra S. Ghadwal
Source: Synlett (article, 2019-07-12)
Field: Chemistry — Organic Chemistry

Stable Carbon-Centered Radicals Based on N-Heterocyclic Carbenes Carbon-centered radicals and diradicaloids based on classical N-heterocyclic carbene (NHC) scaffolds are readily accessible as crystalline solids. The presence of an aryl (Ar) substituent at the C2-position is the key to the remarkable stability of these open-shell species as it provides appropriate room for the spin-density delocalization. Two catalytic as well as high-yielding protocols have been developed to install a suitable aryl group at the C2-position of NHCs. The spin-density in mono-radicals (NHCAr)• is mostly located on the parent carbene carbon (C2) atom. The bridging of two NHCs through a phenylene spacer (C6H4) n enables the isolation of various p-quinodimethane (p-QDM) derivatives, which may be considered as open-shell Kekulé diradicaloids. The diradical character of these NHC-analogues of Thiele (n = 1), Chichibabin (n = 2), and Müller (n = 3) hydrocarbons [(NHC)(C6H4) n (NHC)] can be tuned by a rational choice of the size and/or the topology of spacers. In this account, the synthesis, structure, and properties of this new class of radical hydrocarbons is presented. 1 Introduction 2 NHC-Monoradicals 3 NHC-Diradicaloids 4 Conclusion Carbene ; Chemistry ; Diradical ; Radical ; Substituent ; Carbon atom ; Aryl ; Delocalized electron ; Open shell ; Phenylene ; Catalysis ; Medicinal chemistry ; Stereochemistry ; Organic chemistry ; Polymer ; Ring (chemistry) N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Catalytic Cross-Coupling Reactions ; Organoboron and organosilicon chemistry
Authors: Serge Mignani | João Rodrigues | René Roy | Xiangyang Shi | Valentı́n Ceña | Saı̈d El Kazzouli | Jean‐Pierre Majoral
Source: Drug Discovery Today (review, 2019-03-18)
Field: Materials Science — Polymers and Plastics

Exploration of biomedical dendrimer space based on in-vitro physicochemical parameters: key factor analysis (Part 1) Dendrimer ; Nanomedicine ; Nanotechnology ; Drug delivery ; Macromolecule ; Combinatorial chemistry ; Biochemical engineering ; Chemistry ; Computer science ; Materials science ; Engineering ; Organic chemistry ; Biochemistry ; Nanoparticle Dendrimers and Hyperbranched Polymers ; RNA Interference and Gene Delivery ; Advanced biosensing and bioanalysis techniques
Authors: Peiyang Gu | Yu Chai | Honghao Hou | Ganhua Xie | Yufeng Jiang | Qingfeng Xu | Feng Liu | Paul D. Ashby | Jianmei Lu | Thomas P. Russell
Source: Angewandte Chemie International Edition (article, 2019-07-28)
Field: Materials Science — Materials Chemistry

Stabilizing Liquids Using Interfacial Supramolecular Polymerization The strong electrostatic interactions at the oil-water interface between a small molecule, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin, H<sub>6</sub> TPPS, dissolved in water, and an amine terminated hydrophobic polymer dissolved in oil are shown to produce a supramolecular polymer surfactant (SPS) of H<sub>6</sub> TPPS at the interface with a binding energy that is sufficiently strong to allow an intermolecular aggregation of the supramolecular polymers. SPSs at the oil-water interface are confirmed by in situ real-space atomic force microcopy imaging. The assemblies of these aggregates can jam at the interface, opening a novel route to kinetically trap the liquids in non-equilibrium shapes. The elastic film, comprised of SPSs, wrinkles upon compression, providing a strategy to stabilize liquids in non-equilibrium shapes. Supramolecular chemistry ; Intermolecular force ; Polymer ; Supramolecular polymers ; Polymerization ; Pulmonary surfactant ; Porphyrin ; Materials science ; Chemical engineering ; Molecule ; Polymer chemistry ; Chemistry ; Organic chemistry ; Composite material Pickering emulsions and particle stabilization ; Porphyrin and Phthalocyanine Chemistry ; Surfactants and Colloidal Systems
Authors: Ying Li | Ji Hye Kim | Eun Ha Choi | Ihn Han
Source: Scientific Reports (article, 2019-03-06)
Field: Materials Science — Biomaterials

Promotion of osteogenic differentiation by non-thermal biocompatible plasma treated chitosan scaffold Non-thermal biocompatible plasma (NBP) has recently emerged as an attractive tool for surface modification of biomaterials in tissue engineering. Three dimensional chitosan scaffolds have been widely used in bone tissue engineering due to biodegradable and biocompatible properties. The present study aimed to evaluate osteogenic potential of NBP treated chitosan scaffold. The surface characteristics of scaffolds were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), cell proliferation and differentiation was tested with osteoprogenitor cell line MC3T3-E1. The results show that NBP modified scaffold increase cell metabolic by MTT assay and live/dead assay. More importantly, we evidenced enhancement of osteogenic differentiation on NBP treated scaffolds by an increase of alkaline phosphatase (ALP) activity, high degree of extracellular mineralization and up-regulated osteogenic marker genes expression level. The findings in our study highlighted NBP as the innovative method to modified chitosan scaffold and to fine-tuning the scaffold a more suitable and beneficial biomaterial for in vivo bone tissue engineering and clinical bone defects therapies. Scaffold ; Chitosan ; Alkaline phosphatase ; Tissue engineering ; Biomaterial ; Biomedical engineering ; MTT assay ; Biocompatible material ; Materials science ; Chemistry ; Cell growth ; Nanotechnology ; Biochemistry ; Medicine ; Enzyme Electrospun Nanofibers in Biomedical Applications ; Graphene and Nanomaterials Applications ; Bone Tissue Engineering Materials
Authors: Federico M. Paruzzo | Lyndon Emsley
Source: Journal of Magnetic Resonance (article, 2019-09-14)
Field: Chemistry — Spectroscopy

High-resolution 1H NMR of powdered solids by homonuclear dipolar decoupling The development of homonuclear dipolar decoupling sequences to obtain high-resolution <sup>1</sup>H NMR spectra from solids has recently celebrated its 50th birthday. Over the years, a series of different decoupling schemes have been developed, starting with the pioneering Lee-Goldburg and WAHUHA sequences up to the most recent generation of experimentally optimized phase-modulated schemes such as eDUMBO-1<sub>22</sub> and LG4. These schemes can all yield over an order of magnitude reduction in <sup>1</sup>H NMR linewidths in solids. Here we provide an overview and a broad experimental comparison of the performance of the main sequences, which has so far been absent in the literature, especially between the newest and the oldest decoupling schemes. We compare experimental results obtained using eight different decoupling schemes (LG, WHH-4, MREV-8, BR-24, FSLG/PMLG, DUMBO-1, eDUMBO-1<sub>22</sub> and LG4) on three different microcrystalline powdered samples (alanine, glycine and β-AspAla) and at three different MAS rates (3.0, 12.5 and 22.0 kHz). Finally, since these sequences can be technically demanding, we describe the experimental protocol we have used to optimize these schemes with the aim to provide simple guidelines for the optimization of CRAMPS experiments for all NMR users. Homonuclear molecule ; Materials science ; Resolution (logic) ; Decoupling (probability) ; Proton NMR ; Nuclear magnetic resonance spectroscopy ; Nuclear magnetic resonance ; Chemistry ; Analytical Chemistry (journal) ; Organic chemistry ; Physics ; Molecule ; Computer science Advanced NMR Techniques and Applications ; NMR spectroscopy and applications ; Advanced MRI Techniques and Applications
Authors: N. D. Patel | A. Nocera | G. Alvarez | A. Moreo | S. Johnston | E. Dagotto
Source: Communications Physics (article, 2019-06-21)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Fingerprints of an orbital-selective Mott phase in the block magnetic state of BaFe2Se3 ladders Abstract Resonant Inelastic X-Ray Scattering (RIXS) experiments on the iron-based ladder BaFe 2 Se 3 unveiled an unexpected two-peak structure associated with local orbital ( dd ) excitations in a block-type antiferromagnetic phase. A mixed character between correlated band-like and localized excitations was also reported. Here, we use the density matrix renormalization group method to calculate the momentum-resolved charge- and orbital-dynamical response functions of a multi-orbital Hubbard chain. Remarkably, our results qualitatively resemble the BaFe 2 Se 3 RIXS data, while also capturing the presence of long-range magnetic order as found in neutron scattering, only when the model is in an exotic orbital-selective Mott phase (OSMP). In the calculations, the experimentally observed zero-momentum transfer RIXS peaks correspond to excitations between itinerant and Mott insulating orbitals. We provide experimentally testable predictions for the momentum-resolved charge and orbital dynamical structures, which can provide further insight into the OSMP regime of BaFe 2 Se 3 . Antiferromagnetism ; Strongly correlated material ; Density matrix renormalization group ; Mott insulator ; Inelastic neutron scattering ; Phase (matter) ; Hubbard model ; Spin (aerodynamics) ; Scattering Iron-based superconductors research ; Magnetic and transport properties of perovskites and related materials ; Physics of Superconductivity and Magnetism