jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Gabriela Strnad | Leonard Ciurezu | Andrei Berbecaru | Oana Gîngu
Source: Procedia Manufacturing (article, 2020-01-01)
Field: Materials Science — Polymers and Plastics

Synthesis of Ti-Ni-O Modified Surfaces on Shape Memory Alloys for Biomedical Applications Present paper investigates the relationship between the processing parameters of electrochemical anodization (EA) and the oxide morphology developed on cylindrical surface of 0.4 mm diameter wires of NiTi alloy. The synthesis was done by EA in fluoride based electrolyte by using aqueous solution of 9.34 wt.% H3PO4 and 0.5 wt.% HF. Several experiments were carried out at anodization potential of U = 20, 10, 5, 4, 3, 2 V for a duration of 10 minutes. Longer experiments of 30 min were done at a fine-tuned value of anodization potential of U = 3.5 V. Scanning electron microscopy (SEM and HR-SEM) was used to evaluate the morphology of the Ti-Ni-O oxide layers. The mass loss and the current evolution were analyzed in relation with the anodization results. By using anodization potential of 10 V and 20 V, current densities were of 15-62 mA/mm2 and the process that occurred was an etching one, leading to a mass loss of 4 - 12.5 %. Optimization of EA by fine-tuning the electrical parameters, i.e use of lower anodization potential of 3.5 V and 4 V, lead to current densities of 1 - 1.8 mA/mm2, and to the synthesis of Ti-Ni-O oxide with a well structured nanoporous morphology with pores’ diameter in the 20 - 140 nm range. Anodizing ; Materials science ; Nanoporous ; Scanning electron microscope ; Oxide ; Morphology (biology) ; Etching (microfabrication) ; Chemical engineering ; Current density ; Electrolyte ; Corrosion ; Alloy ; Electrochemistry ; Metallurgy ; Analytical Chemistry (journal) ; Nanotechnology ; Composite material ; Aluminium ; Layer (electronics) ; Chemistry ; Physical chemistry ; Electrode Transition Metal Oxide Nanomaterials ; TiO2 Photocatalysis and Solar Cells ; Anodic Oxide Films and Nanostructures
Authors: Jieze Shen | Tingting Chen | Yue Huang | Qiao Jin | Jian Ji
Source: ACS Applied Materials & Interfaces (article, 2020-07-17)
Field: Materials Science — Polymers and Plastics

New Morphogenetic Strategy Inspired by the Viscoelasticity of Polymers A new morphogenetic strategy was developed to realize continuously modulated and reprogrammable three-dimensional shape transitions by fully exploring the potential of macromolecular conformational modulations. Geometric information was defined in the planar shape memory polymeric sheets through the application of spatially differentiated thermo-temporal conditions in the shape memory creation stage. Due to the viscoelasticity of polymers, nonuniform inner stress distribution was encoded in spite of the homogeneous composition, which was released under the activation of uniform heating. Compared to the traditional shape-programming strategies, the present research offered the opportunity to generate physical patterns by modulating the thermal histories of polymers. It brought the advantages of a continuously regulated degree of discrepancy between different regions, which enabled fine-tuning of the targeted three-dimensional (3D) shape. In addition, suitable annealing treatment could lead to the elimination of thermal history. That is, the geometric information could be erased and re-encoded, making unlimited diverse 3D structures from the same piece of polymer a reality. Materials science ; Viscoelasticity ; Polymer ; Shape-memory polymer ; Planar ; Thermal ; Homogeneous ; Biological system ; Nanotechnology ; Simulated annealing ; Geometric shape ; Computer science ; Statistical physics ; Algorithm ; Geometry ; Composite material ; Computer graphics (images) ; Thermodynamics Polymer composites and self-healing ; Advanced Materials and Mechanics ; Photochromic and Fluorescence Chemistry
Authors: P. K. Sajith | Aleksandar Staykov | Masataka Yoshida | Yoshihito Shiota | Kazunari Yoshizawa
Source: The Journal of Physical Chemistry (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Theoretical Study of the Direct Conversion of Methane to Methanol Using H₂O₂ as an Oxidant on Pd and Au/Pd Surfaces First-principle theoretical study was performed to elucidate the reaction mechanism of the direct conversion of methane to methanol using hydrogen peroxide as an oxidant over Pd and Au/Pd catalysts. We have investigated the effect of Au-Pd alloying and its effect on the reaction steps and energetics and we have provided an understanding of the contribution of surface-exposed Au centers to the overall reaction mechanism. The hydrogen peroxide decomposition reactions to OH groups or surface-adsorbed oxo species and water molecules were compared on the Pd and Au/Pd surfaces as an important preliminary process for the methane oxidation. We have evaluated the C–H bond cleavage energetics assisted by either the OH group or oxo species over Pd and Au/Pd surfaces and compared them to the C–H cleavage energy. Our results show that the products of hydrogen peroxide decomposition significantly reduce the high activation barrier for the hydrogen atom abstraction from methane. The recombination of methyl group and OH group was found to be the rate-determining step for the methanol formation. The proposed reaction pathway in our work provides important insights into the oxidation mechanism by hydrogen peroxide and the fine-tuning of the Pd catalyst by other alloying elements such as Au. Chemistry ; Catalysis ; Hydrogen peroxide ; Methanol ; Methane ; Photochemistry ; Adsorption ; Reaction mechanism ; Decomposition ; Bond cleavage ; Inorganic chemistry ; Hydrogen ; Hydrogen atom abstraction ; Peroxide ; Physical chemistry ; Organic chemistry Catalytic Processes in Materials Science ; Catalysis and Oxidation Reactions ; Catalysts for Methane Reforming
Authors: Xiao Qi | Susan M. Kauzlarich
Source: ACS Applied Nano Materials (article, 2020-05-05)
Field: Materials Science — Materials Chemistry

Ge Nanocages and Nanoparticles via Microwave-Assisted Galvanic Replacement for Energy Storage Applications We report a systematic study on the synthesis of highly monodisperse hollow germanium (Ge) nanoparticles (NPs) via galvanic replacement reactions between GeI2 and Ag NPs. By fine-tuning the synthetic parameters such as temperature, precursor molar ratio, ligand concentration, and so forth, the morphology and surface structure of the Ge NPs can be precisely controlled. We also report a method to synthesize solid Ge NPs and Ag@Ge core–shell metal–semiconductor NPs with a controllable uniform shell thickness. An inward diffusion mechanism for galvanic replacement is proposed and supported by imaging the different stages of the reaction and analysis of the products. This mechanism allows the reaction to be self-terminated and achieves nanometer-sized accuracy. The galvanic reaction may be applied to other semiconductors and could serve as a powerful alternative to the classical nucleation-growth mechanism and subsequently advance the scale-up and further energy storage applications. Nanocages ; Galvanic cell ; Materials science ; Nucleation ; Germanium ; Nanoparticle ; Nanotechnology ; Nanometre ; Semiconductor ; Dispersity ; Single displacement reaction ; Energy storage ; Chemical engineering ; Metal ; Silicon ; Optoelectronics ; Catalysis ; Metallurgy ; Chemistry ; Composite material ; Polymer chemistry Quantum Dots Synthesis And Properties ; Semiconductor materials and devices ; Semiconductor materials and interfaces
Authors: Bong Lee | Alina Valimukhametova | Conor Ryan | Thomas Paz | Fabian Grote | Anton V. Naumov
Source: Nanotechnology (article, 2020-08-05)
Field: Materials Science — Materials Chemistry

Electric field quenching of graphene oxide photoluminescence With the advent of graphene, there has been an interest in utilizing this material and its derivative, graphene oxide (GO) for novel applications in nanodevices such as bio and gas sensors, solid-state supercapacitors and solar cells. Although GO exhibits lower conductivity and structural stability, it possesses an energy band gap that enables fluorescence emission in the visible/near infrared leading to a plethora of optoelectronic applications. In order to allow fine-tuning of its optical properties in the device geometry, new physical techniques are required that, unlike existing chemical approaches, yield substantial alteration of GO structure. Such a desired new technique is one that is electronically controlled and leads to reversible changes in GO optoelectronic properties. In this work, we for the first time investigate the methods to controllably alter the optical response of GO with the electric field and provide theoretical modeling of the electric field-induced changes. Field-dependent GO emission is studied in bulk GO/polyvinylpyrrolidone films with up to 6% reversible decrease under 1.6 V µm<sup>-1</sup> electric fields. On an individual flake level, a more substantial over 50% quenching is achieved for select GO flakes in a polymeric matrix between interdigitated microelectrodes subject to two orders of magnitude higher fields. This effect is modeled on a single exciton level by utilizing Wentzel, Kremer, and Brillouin approximation for electron escape from the exciton potential well. In an aqueous suspension at low fields, GO flakes exhibit electrophoretic migration, indicating a degree of charge separation and a possibility of manipulating GO materials on a single-flake level to assemble electric field-controlled microelectronics. As a result of this work, we suggest the potential of varying the optical and electronic properties of GO via the electric field for the advancement and control over its optoelectronic device applications. Materials science ; Graphene ; Electric field ; Exciton ; Quenching (fluorescence) ; Photoluminescence ; Band gap ; Oxide ; Chemical physics ; Optoelectronics ; Nanotechnology ; Fluorescence ; Condensed matter physics ; Optics Graphene research and applications ; Graphene and Nanomaterials Applications ; Molecular Junctions and Nanostructures
Authors: Federica Scollo | Mimimorena Seggio | Rosa Lucia Torrisi | Rosaria Ornella Bua | Massimo Zimbone | Annalinda Contino | Giuseppe Maccarrone
Source: Applied Nanoscience (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

New fluorescent-labelled nanoparticles: synthesis, characterization and interactions with cysteine and homocysteine to evaluate their stability in aqueous solution Fluorescein ; Fluorescence ; Conjugate ; Cysteine ; Nanochemistry ; Chemistry ; Nanoparticle ; Nanomaterials ; Aqueous solution ; Tyrosine ; Photochemistry ; Biophysics ; Combinatorial chemistry ; Nuclear chemistry ; Materials science ; Organic chemistry ; Nanotechnology ; Biochemistry Nanocluster Synthesis and Applications ; Advanced biosensing and bioanalysis techniques ; Amino Acid Enzymes and Metabolism
Authors: S. B. Feodosyev | V. A. Sirenko | И. А. Господарев | І. І. Бондар | Е. С. Сыркин | Kseniia Mіnakova
Source: 2020 IEEE KhPI Week on Advanced Technology (KhPIWeek) (article, 2020-10-05)
Field: Materials Science — Materials Chemistry

Vibrational Characteristics of Graphene Nanostructures: Stability, Low-Dimensional Peculiarities and Peculiarities of Phonon Expansion and Localization Among the large number of both fundamental and ordinary studies of various physical parts of nanomaterials, the study of graphene structures, such as nanofilms (bigraphene, trigraphene) and nanotubes is undoubtedly a priority. At first sight, from a practical point of view, the vibrational characteristics of these structures do not seem to be as relevant as the spectra of some of the other quasiparticle excitations and their properties (e.g., electronic and magnetic), this is clearly not the case. First of all, the phonon spectrum determines the stability of the structure, which is especially important for the building of nanostructures. Secondly, some properties that are manifested by investigated nanoobjects, or those that are already being applied and are currently being put into effect, or those that are still in demand (such as increased conductivity of graphene structures), manifest themselves with a significant and even decisive participation of phonons. One more thought is the theoretical background of the dynamic stability of carbon nanostructures, which is very important for “fine tuning” the process of their synthesis and determining the operating conditions of devices based on this structures. In addition, an analysis of the rms amplitudes of atomic displacements makes it real to define the limits of applicability of the harmonic approximation when considering vibrations of graphite and bigraphene, trigraphene, i.e., the use of phonons and phonons modes to explain heat capacity, root-mean-square (rms) atomic displacements, thermal expansion of the concepts themselves, which is not a priori obvious. Graphene ; Phonon ; Condensed matter physics ; Nanostructure ; Materials science ; Stability (learning theory) ; Graphene nanoribbons ; Nanotechnology ; Physics ; Computer science Carbon Nanotubes in Composites ; Graphene research and applications ; Fullerene Chemistry and Applications
Authors: Hui Wang | Qingfeng Zhang | Esteban Villarreal | Hao Jing | Kexun Chen
Source: Scholar Commons (University of South Carolina) (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

In Situ Monitoring of Catalytic Molecular Transformations on Noble Metal Nanocatalysts Using Surface-Enhanced Raman Spectroscopy Noble metal nanoparticles have long been of tremendous interest in the nanophotonics and nanocatalysis communities owing to their intriguing size- and shape-dependent plasmonic and catalytic properties. The combination of tunable plasmon resonances with superior catalytic activities on the same noble metal nanoparticle, however, has long been challenging because the research on nanoplasmonics and nanocatalysis deals with nanoparticles in two drastically different size regimes. While tunable plasmon resonances are a unique feature of metallic nanoparticles in the sub-wavelength size regime, heterogeneous catalysis requires the use of substrate-supported sub-5 nm nanoparticulate catalysts. In this mini-review article, we share with the readers several approaches we recently developed toward the realization of plasmonic-catalytic dual-functionalities on a single noble metal nanoparticle. Our approaches involve judicious tailoring of the atomic-level surface structures of sub-wavelength plasmonic nanoparticles through either kinetically controlled seed-mediated nanocrystal growth or regioselective surface etching. These structurally tailored, dual-functional nanoparticles serve as both substrates for surface-enhanced Raman spectroscopy (SERS) and free-standing nanoparticulate catalysts. Using SERS as a molecular finger-printing spectroscopic tool, we have been able to track detailed structural evolution of molecular adsorbates in real time during catalytic reactions. The quantitative insights gained from the in situ SERS measurements shed light on the detailed relationships between interfacial molecule-transforming behaviors and the atomic-level surface structures of noble metal nanocatalysts. Nanomaterial-based catalyst ; In situ ; Raman spectroscopy ; Catalysis ; Noble metal ; Surface-enhanced Raman spectroscopy ; Materials science ; Metal ; Nanotechnology ; Chemical engineering ; Chemistry ; Metallurgy ; Raman scattering ; Physics ; Organic chemistry ; Optics ; Engineering Machine Learning in Materials Science ; Catalytic Processes in Materials Science ; Nanomaterials for catalytic reactions
Authors: Lars Grunenberg | Gökçen Savaşçı | Maxwell W. Terban | Viola Düppel | Igor Moudrakovski | Martin Etter | Robert E. Dinnebier | Christian Ochsenfeld | Bettina V. Lotsch
Source: ChemRxiv (preprint, 2020-09-22)
Field: Materials Science — Materials Chemistry

Amine-linked Covalent Organic Frameworks as a Powerful Platform for Post-Synthetic Modification: Structure Interconversion and Combined Linkage- and Pore-Wall-Modification Covalent organic frameworks have emerged as a powerful synthetic platform for installing and interconverting dedicated molecular functions on a crystalline polymeric backbone with atomic precision. Here, we present a novel strategy to directly access amine-linked covalent organic frameworks, which serve as a scaffold enabling pore-wall modification and linkage-interconversion by new synthetic methods based on Leuckart-Wallach reduction with formic acid and ammonium formate. Frameworks connected entirely by secondary amine linkages, mixed amine/imine bonds, and partially formylated amine linkages are obtained in a single step from imine-linked frameworks, or directly from corresponding linkers in a one-pot crystallisation-reduction approach. The new, 2D amine-linked covalent organic frameworks, rPI-3-COF, rTTI-COF, and rPy1P-COF, are obtained with high crystallinity and large surface areas. Secondary amines, installed as reactive-sites on the pore wall, enable further post-synthetic functionalisation to access tailored covalent organic frameworks, with increased hydrolytic stability, as potential heterogeneous catalysts. Covalent bond ; Imine ; Amine gas treating ; Chemistry ; Dynamic covalent chemistry ; Combinatorial chemistry ; Covalent organic framework ; Surface modification ; Formate ; Polymer chemistry ; Organic chemistry ; Catalysis ; Molecule ; Supramolecular chemistry Covalent Organic Framework Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Advanced Photocatalysis Techniques
Authors: Wei Xiong | Wen-Ying Chang | Shi Dong | Lijiang Yang | Zi‐You Tian | Hao Wang | Zhengchu Zhang | Xuhao Zhou | Er‐Qiang Chen | Hua Lu
Source: ChemRxiv (preprint, 2020-02-28)
Field: Materials Science — Biomaterials

Geminal Dimethyl Substitution Enabled Controlled Ring-Opening Polymerization and Selective Depolymerization of Penicillamine-Derived β-Thiolactones To access infinitely recyclable plastics, one key is to design thermodynamically neutral systems based on dynamic bonds for easy manipulation of the polymerization and the reverse depolymerization under low energy cost. Here, we present the controlled ring-opening polymerization of various penicillamine-derived β-thiolactones and the highly specific depolymerization of the resultant polythioesters (PNR-PenTE) for complete monomer recycling. The gem-dimethyl group confers better ROP control by reducing the activity of the chain-end thiolate groups and stabilizing the thioester linkages in the polymer backbone. High molar mass and narrow dispersity PNR-PenTE are conveniently accessible at room temperature bearing well-defined end groups and tunable side chains. PNR-PenTE can be tailored with water solubility, and/or be easily fabricated into persistent films or fibers with interesting thermal and mechanical properties. Most importantly, PNR-PenTE can be recycled to pristine enantiopure β-thiolactones at >95% conversion in a well-controlled unzipping fashion within min to hours at room temperature. Overall, this work may streamline the rapid development of a wide range of polythioesters with immense application potential as self-immolative building blocks, high value biomaterials, and sacrificial domain for nanolithography. Depolymerization ; Polymer chemistry ; Monomer ; Polymerization ; Polymer ; Materials science ; Ring-opening polymerization ; Chemistry ; Chemical engineering ; Composite material biodegradable polymer synthesis and properties ; Carbon dioxide utilization in catalysis ; Polyoxometalates: Synthesis and Applications
Authors: Venty Suryanti | Fajar Rakhman Wibowo | Sekar Handayani
Source: Indonesian Journal of Chemistry (article, 2020-03-02)
Field: Chemistry — Spectroscopy

Methyl-3-(2-hidroxy-5-nitrophenyl amino)-3-phenylpropanoate Based Colorimetric Sensor for Oxyanions A colorimetric anion sensor of methyl-3-(2-hydroxy-5-nitrophenyl amino)-3-phenylpropanoate bearing –OH and –NH groups as binding sites and nitrophenyl as a signaling unit, has been successfully accomplished. The compound functioned as a colorimetric chemosensor for H2PO4– and AcO–, in particular, the sensor showed significant naked-eye detectable color change from colorless to light yellow. In contrast, no color change was detected upon addition of other anions such as SO42–, NO3–, and CIO4–. The anion sensing ability of the sensor was further investigated by UV-Vis absorption spectroscopy in acetone. Characteristic UV-Vis spectra changes were revealed upon addition of H2PO4– and AcO–. Chemistry ; Acetone ; Naked eye ; Colorimetry ; Ion ; Absorption (acoustics) ; Absorption spectroscopy ; Photochemistry ; Nuclear chemistry ; Chromatography ; Detection limit ; Organic chemistry Molecular Sensors and Ion Detection ; Advanced Chemical Sensor Technologies ; Analytical Chemistry and Sensors
Authors: Letitia Burgess | Hannah Wilson | Alex R. Jones | Sam Hay | Louise S. Natrajan
Source: Frontiers in Chemistry (article, 2020-12-21)
Field: Materials Science — Materials Chemistry

Assessing the Covalent Attachment and Energy Transfer Capabilities of Upconverting Phosphors With Cofactor Containing Bioactive Enzymes Upconverting phosphors (UCPs) convert multiple low energy photons into higher energy emission via the process of photon upconversion and offer an attractive alternative to organic fluorophores for use as luminescent probes. Examples of biosensors utilizing the apparent energy transfer of UCPs and nanophosphors (UCNPs) with biomolecules have started to appear in the literature but very few exploit the covalent anchoring of the biomolecule to the surface of the UCP to improve the sensitivity of the systems. Here, we demonstrate a robust and versatile method for the covalent attachment of biomolecules to the surface of a variety of UCPs and UCNPs in which the UCPs were capped with functionalized silica in order to provide a surface to covalently conjugate biomolecules with surface-accessible cysteines. Variants of BM3Heme, cytochrome C, glucose oxidase, and glutathione reductase were then attached via maleimide-thiol coupling. BM3Heme, glucose oxidase, and glutathione reductase were shown to retain their activity when coupled to the UCPs potentially opening up opportunities for biosensing applications. Biomolecule ; Covalent bond ; Biosensor ; Chemistry ; Surface modification ; Glucose oxidase ; Nanotechnology ; Combinatorial chemistry ; Materials science ; Organic chemistry ; Biochemistry Luminescence Properties of Advanced Materials ; Luminescence and Fluorescent Materials ; bioluminescence and chemiluminescence research