jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Kefeng Ping | Alan Braschinsky | Mahboob Alam | Rohit Bhadoria | Valdek Mikli | Arvo Mere | Jaan Aruväli | Päärn Paiste | Sergei Vlassov | Mati Kook | Mihkel Rähn | Väino Sammelselg | Kaido Tammeveski | Nadežda Kongi | Pavel Starkov
Source: ChemRxiv (preprint, 2019-02-07)
Field: Chemistry — Inorganic Chemistry

Fused Hybrid Linkers for Metal–Organic Frameworks-Derived Bifunctional Oxygen Electrocatalysts &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;Preparation of electrocatalysts often relies on the use of multiple starting materials – inorganic salts or organometallic precursors, nanostructured carbon supports, organic additives, dopants and carbonization under modifying atmospheres (e.g. NH&lt;sub&gt;3 &lt;/sub&gt;or H&lt;sub&gt;2&lt;/sub&gt;) – with the examples of electrocatalysts arising from a single precursor being much less common. Herein, we have surveyed a series of heterobivalent scaffolds to identify an iron/benzimidazole-based metal– organic framework as a uniform starting material. By merging the catechol and imidazole units together, we get direct entry into a highly efficient bifunctional oxygen electrocatalyst, which alleviates the need for additional dopants and modifying conditions (ORR: &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;on&lt;/sub&gt; = 1.01 V, &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;1/2&lt;/sub&gt; = 0.87 V vs. RHE in 0.1 M KOH; OER: 1.60 V @10 mA cm&lt;sup&gt;–2&lt;/sup&gt; in 0.1 M KOH; ∆&lt;i&gt;E&lt;/i&gt; = 0.73 V). We demonstrate that by fine-tuning the chemical nature of an organic linker, one is able modulate the electrochemical properties of a single precursor-derived electrocatalyst material. &lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; Bifunctional ; Electrocatalyst ; Chemistry ; Dopant ; Electrochemistry ; Metal ; Nanotechnology ; Catalysis ; Materials science ; Organic chemistry ; Electrode ; Doping ; Physical chemistry Metal-Organic Frameworks: Synthesis and Applications ; Electrocatalysts for Energy Conversion ; Polyoxometalates: Synthesis and Applications
Authors: Boon Peng Lee
Source: DR-NTU (Nanyang Technological University) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Plasma enhanced chemical vapor deposition growth of vanadium dioxide Vanadium Oxide interesting compound which have energy saving properties in energy conservation applications. VO2 are chosen instead of other oxidation state are partly because of their near room temperature critical phase transition temperature (Tc) and atomic structures. VO2 Exhibit reversible phase transition properties from tetragonal rutile to monoclinic structure when it exceeds 680C. To achieve high quality VO2 thin film on a soda lime glass substrate, understanding nucleation mechanism to fine tune the process condition is essential. Are discussed in this report. There are multiple deposition configurations or techniques to achieve VO2 thin film. However, Plasma Enhanced Chemical Vapor Deposition (PECVD) was used to synthesize in this project due to high deposition rate and good uniformity. The morphology of the samples was studied and analyzed using Atomic force microcopy (AFM) and scanning electron microscopy (SEM). The chemical composition and transmittance are examined using Energy dispersive X-ray spectroscopy (EDX) and UV-Vis spectroscopy (UV-Vis). Lastly the phases of VO2 thin film is recorded using X-Ray Diffraction (XRD). The experimental results show at 〖450〗^0 C growth temperature, VO2 thin film will be nucleate at optimum condition when the duration of growth duration is at 4 minutes with vacuum chamber of 1 torr, 200W of plasma generator power, argon and oxygen flow rate are at 200 and 10 standard cubic centimeters per minute respectively. The results regarding synthesis of VO2 thin film and film thermochromic properties were discussed in this report. Further studies were also recommended to optimize the effectiveness of synthesizing VO2 thin film. Vanadium dioxide ; Vanadium ; Deposition (geology) ; Chemistry ; Chemical vapor deposition ; Environmental chemistry ; Materials science ; Environmental science ; Inorganic chemistry ; Nanotechnology ; Thin film ; Organic chemistry ; Geology Catalytic Processes in Materials Science ; Transition Metal Oxide Nanomaterials
Authors: M. B. Silva Neto | F. A. Pinheiro
Source: Physical review. B./Physical review. B (article, 2019-12-12)
Field: Materials Science — Materials Chemistry

Controlling spontaneous emission via electronic correlations and temperature in transparent oxides We study spontaneous emission of two-level quantum emitter agglomerates embedded in transparent oxides. The two levels correspond to the splitting between vacancy impurity states $F,\phantom{\rule{0.28em}{0ex}}{F}^{+}$, and ${V}^{\ensuremath{-}}$ color centers, whereas correlations are due to narrow bands in transition-metal oxides with ${\mathrm{ABO}}_{3}$ perovskite structures. For these systems, we put forward a mechanism to control light emission in which micrometer-size vacancy-rich regions play the role of cavity resonators for the emitted radiation with normal frequencies mode volumes, and emission linewidths determined by their size and material properties. We argue that a physical scenario in which the emitter's natural frequency and linewidth can be fine-tuned via electronic correlations or temperature explains unusual features in the experimental photoluminescence spectra of Ar-irradiated ${\mathrm{SrTiO}}_{3}$. By unveiling the role of electronic correlations on spontaneous emission in transparent oxides, we hope our findings help set the basis for the design of controllable engineered solid-state single-photon sources. Laser linewidth ; Photoluminescence ; Materials science ; Spontaneous emission ; Perovskite (structure) ; Mesoscopic physics ; Spectral line ; Photon ; Emission spectrum ; Common emitter ; Vacancy defect ; Optoelectronics ; Atomic physics ; Condensed matter physics ; Laser ; Optics ; Physics ; Chemistry ; Crystallography Electronic and Structural Properties of Oxides ; Semiconductor materials and devices ; Perovskite Materials and Applications
Authors: Jaume García‐Amorós | M. Cidália R. Castro | Santi Nonell | Susana Vílchez | Jordi Esquena | M. Manuela M. Raposo | Dolores Velasco
Source: RepositóriUM (Universidade do Minho) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Adaptable Photochromic Switches with Self-Aggregating Heterocyclic Azo Dyes It is well-known that the thermal isomerization kinetics of photochromic azo dyes can be modulated by subtle changes in their chemical architecture. However, the availability of an orthogonal input to control the thermal relaxation of azo dyes is essential to enable access to multifunctional and adaptive photochromic switches based on these particular organic chromophores. In this work, we have designed and synthesized a new family of green-light-activated heterocyclic azo derivatives that modify their switching capabilities as a function of concentration. In this line, we have investigated their self-assembly and the nature of the supramolecular aggregates formed by means of dynamic light scattering, polarized optical microscopy, and X-ray diffraction. Indeed, imparting control over the self-assembly of these organic dyes allows to fine-tune their thermal relaxation time and produce adaptable photochromic switches. Specifically, swapping the azo dye concentration between values located above and below the corresponding critical aggregation concentration modifies significantly the relaxation time up to 250 times, i.e., from the millisecond to the microsecond timescale. Moreover, the optical density of the system can be switched back and forth hundreds of times, for both diluted and concentrated solutions, without any sign of fatigue. Photochromism ; Chemistry ; Chromophore ; Molecular switch ; Isomerization ; Microsecond ; Photochemistry ; Supramolecular chemistry ; Relaxation (psychology) ; Optical switch ; Kinetics ; Light scattering ; Chemical engineering ; Chemical physics ; Scattering ; Optoelectronics ; Organic chemistry ; Molecule ; Optics ; Materials science ; Catalysis Photochromic and Fluorescence Chemistry ; Supramolecular Self-Assembly in Materials ; Luminescence and Fluorescent Materials
Authors: Andressa Trentin
Source: UNESP Institutional Repository (São Paulo State University) (article, 2019-10-08)
Field: Chemistry — Inorganic Chemistry

Estrutura e propriedades eletroquímicas de revestimentos híbridos PMMA-sílica modificados com íons cério e lítio This work reports on a detailed investigation of the structural and electrochemical properties of poly(methyl methacrylate) (PMMA)-silica coatings. Raman spectroscopy and thermal analysis showed that the fine-tuning of the benzoyl peroxide (BPO) amount, as a critical synthesis parameter, improves the polymerization efficiency of methyl methacrylate (MMA), leading to a highly cross-linked hybrid structure. Electrochemical impedance spectroscopy (EIS) showed for coatings deposited on carbon steel (A1020) and Al alloy (AA7075) a quasi-ideal capacitive impedance response, maintaining the low frequency impedance modulus of up to 10 GΩ cm2 essentially unchanged during 19 months of immersion in 3.5% NaCl. Although high performance passive coatings have been developed, pitting can significantly affect their durability. Hence, active corrosion inhibition induced by lithium and cerium ions in PMMA-silica sol-gel coatings was investigated. The addition of lithium carbonate yielded coatings with improved connectivity of nanometric silica cross-link nodes and stronger adhesion to the aluminum substrate. EIS results showed that higher lithium concentrations result in an increased impedance modulus and induce the self-healing ability, extending significantly the service life of the coatings. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) suggest that the regeneration process occurs by means of lithium ions leaching from the adjacent coating towards the corrosion spot, which is restored by a protective layer of Li containing aluminum hydroxide species. Finally, coatings loaded with Ce(III) and Ce(IV) provided long term protection for aluminum alloy, however only Ce(IV) imparts active inhibition due to the passivation of cathodic sites by forming highly insoluble Ce oxides and hydroxides. Intermediate Ce(IV) concentrations proved to be more effective in improving the barrier property combined with active protection of intact and damaged coatings over immersion time. In brief, this study found a close relationship between optimized structure, anticorrosive effectiveness and self-healing activity induced by lithium and cerium ions in PMMA-silica coatings, highlighting their high potential of the material for the effective protection of metallic surface. Materials science ; Composite material Pigment Synthesis and Properties
Authors: Luca Bagnarelli | Carlo Santini | Marina Porchia | F. Tisato | C. Marzano | Valentina Gandin | Maura Pellei
Source: Unicam Scientific Publications (University of Camerino) (article, 2019-01-01)
Field: Chemistry — Organic Chemistry

Synthesis, reactivity and cytotoxic properties of water soluble coinage metal N-Heterocyclic Carbene complexes Even if the chemistry of carbenes was discovered fifty years ago, it is only recently that N-heterocyclic carbenes (NHCs)1 have fascinated the researchers showing them to be suitable candidates for medicinal chemistry applications due to both the versatility to bond a lot of transition metals and the ease to fine tuning their structure, influencing both their stability and solubility. NHC complexes of coinage metals have been widely investigated for their variable applications and diverse structural properties and recently they showed to be good candidates as an alternative to cisplatin, exhibiting encouraging results in the field of anticancer drugs research2,3. In the last years, we have developed several classes of coinage metal-NHC complexes obtained from the precursors {[HB(RImH)3]Br2} (R = Bz, Mes and t-Bu), {[H2B(BzTzH)2]Br}, {H2C(HTzR)2} and {H2C(HImR)2} (R = (CH2)3SO3- or (CH2)2COO-).2 Recently we have focused the research work on 11th group metal-NHCs complexes obtained from water soluble 1,3-symmetrically and 1,3-unsymmetrically substituted NHCs precursors based on imidazole and benzoimidazole scaffolds4-6. More recently we have synthesized and investigated the cytotoxic activity of the novel NHC ligand precursor [HTz(pNO2Bz)2]Br, and the corresponding metal complexes M[Tz(pNO2Bz)2]Br (M = Cu(I), Ag(I) or Au(I))7. In addition, novel water soluble bis(NHCSO3)CuCl complexes (NHCSO3 = HImBn,PrSO3, Na(4-Me)ImPrSO3 and NaBzimPrSO3), derived by the sulfonated N-heterocyclic carbene precursors HImBn,PrSO3 (3-(1-benzyl-1H-imidazol-3-ium-3-yl)propane-1-sulfonate), Na(4-Me)HImPrSO3 (sodium 3,3'-(4-methyl-1H-imidazole-3-ium-1,3-diyl)dipropane-1-sulfonate) and NaHBzimPrSO3 (sodium 3,3'-(1H-benzo[d]imidazole-3-ium-1,3-diyl)dipropane-1-sulfonate), have been synthesized8. The in vitro antitumor effects of the complexes and the corresponding free ligands were evaluated on a panel of various human tumour cell lines. Their cytotoxic properties were also evaluated against non-transformed human cells and on a cellular model of cisplatin-resistance. Carbene ; Reactivity (psychology) ; Chemistry ; Metal ; Cytotoxic T cell ; Stereochemistry ; Combinatorial chemistry ; Organic chemistry ; Catalysis ; Biochemistry ; Medicine ; In vitro N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Catalytic Cross-Coupling Reactions ; Asymmetric Hydrogenation and Catalysis
Authors: Sunanda Neupane
Source: NDSU Repository (North Dakota State University) (article, 2019-01-01)
Field: Materials Science — Biomaterials

Understanding the Interaction Between Enzymes and Nanomaterials The rapid development of nanoparticles (NPs) has impacted many fields including energy efficiency, material science, biosensing, and medical therapeutics. Recently, NPs have been utilized to immobilize enzymes. The so-formed enzyme- NP complex show great potential to increase the reusability of enzymes and catalytic efficiencies. Enzyme-NP complex can also advance enzyme delivery for therapeutics where NPs serve as the enzyme carrier. In all applications, the contact of NPs with biomacromolecules, especially proteins, is either necessary or inevitable, which can lead to alterations in adsorbed enzyme structure and function. In biocatalysis, such changes often reduce the desired catalytic activity; in living organisms these changes can even cause protein malfunction, raising concerns about public health and nanotoxicity. Therefore, understanding the correlation of enzyme structure and activity upon contact with NPs is essential.&#13;\nWhile enzyme activities can often be determined, the details of enzyme structural changes caused by NPs are underexplored for most enzyme-NP complexes. Obtaining the structural information is challenging due to the relatively large size of the complexes, high heterogeneity in enzyme binding, and complexities caused by the presence of NPs which limit most structure determination approaches. These challenges were overcome using a set of biophysical techniques especially site-directed spin labeling (SDSL) with Electron Paramagnetic Resonance (EPR). SDSL-EPR can measure site-specific structural information in the native state of enzyme/NP systems, regardless of the complexity, primarily due to its ?penetrating? power which is only sensitive to the motion of the spin label. &#13;\nThe focus of this dissertation was on T4 lysozyme (T4L), a representing model enzyme proven useful in many works. Gold Nanoparticles (AuNPs), Gold Nanorods (AuNRs), Silica Nanoparticles (SiNPs), and Carbon Nanotubes (CNTs) were the studied NPs.&#13;\nThe interaction of T4L with each NPs was unique. The local structural information and the orientation of T4L in each NP was revealed based on which the possible docking mechanism for each case was proposed. The ultimate goals to reveal the structure-function relationship of enzymes on NPs and utilize this information to fine-tune enzyme adsorption on various NPs to 1) avoid NPs aggregation and 2) optimize NPs as enzyme carriers were met. Computer science Nanoparticle-Based Drug Delivery ; Enzyme Catalysis and Immobilization ; Graphene and Nanomaterials Applications
Authors: Federica Burla | Simone Dussi | Cristina Martinez-Torres | Justin Tauber | Jasper van der Gucht | Gijsje H. Koenderink
Source: arXiv (Cornell University) (preprint, 2019-11-14)
Field: Materials Science — Biomaterials

Disorder protects collagen networks from fracture Collagen forms the structural scaffold of connective tissues in all mammals. Tissues are remarkably resistant against mechanical deformations because collagen molecules hierarchically self-assemble in fibrous networks that stiffen with increasing strain. Nevertheless, collagen networks do fracture when tissues are overloaded or subject to pathological conditions such as aneurysms. Prior studies of the role of collagen in tissue fracture have mainly focused on tendons, which contain highly aligned bundles of collagen. By contrast, little is known about fracture of the orientationally more disordered collagen networks present in many other tissues such as skin and cartilage. Here, we combine shear rheology of reconstituted collagen networks with computer simulations to investigate the primary determinants of fracture in disordered collagen networks. We show that the fracture strain is controlled by the coordination number of the network junctions, with less connected networks fracturing at larger strains. The hierarchical structure of collagen fine-tunes the fracture strain by providing structural plasticity at the network and fiber level. Our findings imply that structural disorder provides a protective mechanism against network fracture that can optimize the strength of biological tissues. Fracture (geology) ; Materials science ; Collagen fiber ; Composite material ; Anatomy ; Biology Collagen: Extraction and Characterization ; Cellular Mechanics and Interactions ; Bone health and osteoporosis research
Authors: M. Cole | Gary J. Fisher | John J. Voorhees
Source: Journal of Investigative Dermatology (article, 2019-04-19)
Field: Materials Science — Polymers and Plastics

437 Development and characterization of biomimetic dermal matrices to study the impact of aging on human fibroblast function Creep ; Viscoelasticity ; Human skin ; Materials science ; Modulus ; Composite material ; Biomedical engineering ; Strain (injury) ; Skin Aging ; Deformation (meteorology) ; Compression (physics) ; Anatomy ; Medicine ; Dermatology Textile materials and evaluations ; Skin Protection and Aging
Authors: A. K. Patra | Adrienn Ruzsinszky
Source: arXiv (Cornell University) (preprint, 2019-07-23)
Field: Materials Science — Materials Chemistry

Revealing the role of van der Waals interactions in thiophene adsorption on copper surfaces Accurate modeling of electronic and structural properties of organic molecule-metal interfaces are challenging problems because of the complicated electronic distribution of molecule and screening of charges at the metallic surface. This is also the reason why the organic/inorganic system can be engineered for several applications by fine-tuning the metallic work function. Here, we use density-functional theory (DFT) calculations with different level of functional approximations for a systematic study of thiophene interacting with Copper surfaces. In particular, we considered adsorbed structures with the thiophene molecule seated on the top site, with the S atom of the molecule located on the top of a Cu atom. In this work, we find that the weak chemisorption hypothesis of thiophene binding on the copper surface is well justified by the two meta-GGAs-based approximations, SCAN and SCAN+rVV10. PBE-GGA and TM meta-GGA describe it as a physisorption phenomenon by significantly underestimating the adsorption energies. Calculated adsorption energy curves reveal that non-local dispersion interaction between the molecule and metallic surface predominantly controls the bonding mechanism and thus, modifies the copper's work function. Our results imply that semi-local functionals without any kind of van der Waals (vdW) correction can often misinterpret this as physisorption, while, a fortuitous error cancellation can give a right description of this adsorption picture for a wrong reason as in the case of SCAN. The calculated density of states of the adsorbed molecule shows that the long-range vdW correction of SCAN+rVV10 causes more than enough hybridization between the \textit{p} orbitals of S atom and the copper \textit{d}-bands and therefore overestimates the adsorption energies by an average of 16\%. Physisorption ; van der Waals force ; Chemisorption ; Adsorption ; Thiophene ; Copper ; Density functional theory ; Molecule ; Chemical physics ; Work function ; Chemistry ; Computational chemistry ; Atom (system on chip) ; Work (physics) ; Van der Waals surface ; Metal ; Materials science ; Physical chemistry ; Van der Waals radius ; Thermodynamics ; Physics ; Organic chemistry Advanced Thermoelectric Materials and Devices ; Molecular Junctions and Nanostructures ; Advanced Chemical Physics Studies
Authors: Radomir Timchenko | D.А. Krishko | I.V. Khoruzhenko
Source: ACADEMIC JOURNAL Series Industrial Machine Building Civil Engineering (article, 2019-07-05)
Field: Materials Science — Materials Chemistry

Choice substantiation of a folded foundation model via laboratory experiment The examples of recent developments of foundation thin-walled structures and their applications are presented. It is notedthat the purpose is to develop a method for conducting experimental studies of contact interaction between a folded shellfoundation and a deformed base. The purpose of the laboratory tray research is to determine the optimal characteristics of thesuggested foundation design. The article suggested a method for conducting a laboratory tray experiment to compare the operationof two models of folded shell foundations. The main stages of conducting the scientific experiment have been describedand the basic principles of selecting materials, devices and equipment for carrying out the experiment have been considered.The conduct of the experiment including data recording for each foundation model has been described. As a result,subsidence data for each foundation model have been obtained. The findings have been analyzed; subsidence graphs for eachfoundation design have been built. It is concluded that better distribution of external load to the foundation system elementsis achieved due to the application of a hinged joint of prismatic folds with supporting beams. It has been found that the chosenparameters of the second foundation model complied with the optimized results of the experiment planning and enabledto demonstrate the properties of the foundation system load redistribution better. Foundation (evidence) ; Experimental data ; Computer science ; Structural engineering ; Mechanical engineering ; Engineering ; Mathematics Structural mechanics and materials