jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Francesco Presel | Alfonso Gijón | Eduardo Hernández | Paolo Lacovig | Silvano Lizzit | Dario Alfè | Alessandro Baraldi
Source: ACS Nano (article, 2019-10-07)
Field: Materials Science — Materials Chemistry

Translucency of Graphene to van der Waals Forces Applies to Atoms/Molecules with Different Polar Character Graphene has been proposed to be either fully transparent to van der Waals interactions to the extent of allowing switching between hydrophobic and hydrophilic behavior, or partially transparent (translucent), yet there has been considerable debate on this topic, which is still ongoing. In a combined experimental and theoretical study we investigate the effects of different metal substrates on the adsorption energy of atomic (argon) and molecular (carbon monoxide) adsorbates on high-quality epitaxial graphene. We demonstrate that while the adsorption energy is certainly affected by the chemical composition of the supporting substrate and by the corrugation of the carbon lattice, the van der Waals interactions between adsorbates and the metal surfaces are partially screened by graphene. Our results indicate that the concept of graphene translucency, already introduced in the case of water droplets, is found to hold more generally also in the case of single polar molecules and atoms, which are apolar. van der Waals force ; Graphene ; Chemical physics ; Molecule ; Adsorption ; Polar ; Van der Waals strain ; Materials science ; Van der Waals surface ; Carbon monoxide ; Carbon fibers ; Nanotechnology ; Chemistry ; Van der Waals radius ; Physical chemistry ; Physics ; Organic chemistry Graphene research and applications ; Carbon Nanotubes in Composites ; Fullerene Chemistry and Applications
Authors: Hussein Issa | Nourrdine Chaouati | Joumana Toufaily | Tayssir Hamieh | Alexander Sachse | Ludovic Pinard
Source: ChemCatChem (article, 2019-07-04)
Field: Chemistry — Inorganic Chemistry

Toolbox of Post‐Synthetic Mordenite Modification Strategies: Impact on Textural, Acidic and Catalytic Properties Abstract Which post‐synthetic modification strategy is the best suited for the generation of particular textural or chemical features in mordenite for a desired catalytic application? The aim of this contribution is to shed light on the effective quality of zeolite hierarchization through the rational study of structure/catalytic property dependency. Our study focused on mordenite, as this zeolite is of particular importance due to its strong acidity and monodimensional channel system, which explains why mordenite is industrially extensively employed. A toolbox of post‐synthetic hierarchization strategies on aluminum rich and poor mordenites has been developed based on basic treatments assisted by CTAB and pyridine at various temperatures (in conventional and microwave heating) and acid HF etching in aqueous and organic medium. A systematic study of over 30 post‐synthetically modified mordenites was conducted, which allowed us to assess the impact of each hierarchization strategy on textural, morphological, chemical and catalytic properties. Major correlations between structural features and catalytic activity, selectivity and stability in both the monomolecular n ‐hexane cracking and the bimolecular toluene disproportionation were deduced. Mordenite ; Zeolite ; Catalysis ; Chemistry ; Disproportionation ; Fluid catalytic cracking ; Selectivity ; Toluene ; Chemical engineering ; Organic chemistry Zeolite Catalysis and Synthesis ; Mesoporous Materials and Catalysis ; Catalytic Processes in Materials Science
Authors: Marianna Barbalinardo | Matteo Di Giosia | Iryna Polishchuk | Giulia Magnabosco | Simona Fermani | Fabio Biscarini | Matteo Calvaresi | Francesco Zerbetto | Graziella Pellegrini | Giuseppe Falini | Boaz Pokroy | Francesco Valle
Source: Journal of Materials Chemistry B (article, 2019-01-01)
Field: Materials Science — Biomaterials

Retinoic acid/calcite micro-carriers inserted in fibrin scaffolds modulate neuronal cell differentiation The controlled release of cell differentiating agents is crucial in many aspects of regenerative medicine. Here we propose the use of hybrid calcite single crystals as micro-carriers for the controlled and localized release of retinoic acid, which is entrapped within the crystalline lattice. The release of retinoic acid occurs only in the proximity of stem cells, upon dissolution of the calcite hybrid crystals that are dispersed in the fibrin scaffold. These hybrid crystals provide a sustained dosage of the entrapped agent. The environment provided by this composite scaffold enables differentiation towards neuronal cells that form a three-dimensional neuronal network. Retinoic acid ; Fibrin ; Calcite ; Cell ; Cell biology ; Materials science ; Biophysics ; Nanotechnology ; Chemistry ; Biochemistry ; Biology ; Immunology ; Mineralogy ; Gene Calcium Carbonate Crystallization and Inhibition ; Bone Tissue Engineering Materials ; Bone and Dental Protein Studies
Authors: Nils Hanik | Camila Utsunomia | Shuzo Arai | Ken’ichiro Matsumoto | Manfred Zinn
Source: Frontiers in Bioengineering and Biotechnology (article, 2019-11-05)
Field: Materials Science — Biomaterials

Influence of Unusual Co-substrates on the Biosynthesis of Medium-Chain-Length Polyhydroxyalkanoates Produced in Multistage Chemostat A two-stage chemostat cultivation was used to investigate the biosynthesis of functionalized medium-chain-length polyhydroxyalkanoate (mcl-PHA) in the β-oxidation weakened strain of <i>Pseudomonas putida</i> KTQQ20. Chemostats were linked in sequence and allowed separation of biomass production in the first stage from the PHA synthesis in the second stage. Four parallel reactors in the second stage provided identical growth conditions and ensured that the only variable was the ratio of decanoic acid (C10) to an unusual PHA monomer precursor, such as 10-undecenoic acid (C11:1) or phenylvaleric acid (PhVA). Obtained PHA content was in the range of 10 to 25 wt%. When different ratios of C10 and C11:1 were fed to <i>P. putida</i>, the produced PHA had a slightly higher molar ratio in favor of C11:1-based 3-hydroxy-10-undecenoate. However, in case of PhVA a significantly lower incorporation of 3-hydroxy-5-phenylvalerate over 3-hydroxydecanoate took place when compared to the ratio of their precursors in the feed medium. A result that is explained by a less efficient uptake of PhVA compared to C10 and a 24% lower yield of polymer from the aromatic fatty acid ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>y</mml:mi> <mml:mrow> <mml:mfrac><mml:mrow><mml:mi>P</mml:mi> <mml:mi>H</mml:mi> <mml:mi>A</mml:mi> <mml:mo>-</mml:mo> <mml:mi>M</mml:mi></mml:mrow> <mml:mrow><mml:mi>P</mml:mi> <mml:mi>h</mml:mi> <mml:mi>V</mml:mi> <mml:mi>A</mml:mi></mml:mrow> </mml:mfrac> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> = 0.25). In addition, PHA isolated from cultivations with PhVA resulted in the number average molecular weight <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mrow> <mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow> <mml:mrow><mml:mi>n</mml:mi></mml:mrow> </mml:msub> </mml:mrow> <mml:mo>¯</mml:mo></mml:mover> </mml:math> two times lower than the PHA produced from C10 alone. Detection of products from PhVA metabolism in the culture supernatant showed that uptaken PhVA was not entirely converted into PHA, thus explaining the difference in the yield polymer from substrate. It was concluded that PhVA or its related metabolites increased the chain transfer rate during PHA biosynthesis in <i>P. putida</i> KTQQ20, resulting in a reduction of the polymer molecular weight. Polyhydroxyalkanoates ; Chemostat ; Yield (engineering) ; Pseudomonas putida ; Biosynthesis ; Monomer ; Decanoic acid ; Substrate (aquarium) ; Bioreactor ; Strain (injury) ; Polymer ; Biochemistry ; Chemistry ; Organic chemistry ; Materials science ; Biology ; Bacteria ; Enzyme biodegradable polymer synthesis and properties ; Microplastics and Plastic Pollution ; Biopolymer Synthesis and Applications
Authors: Ricarda Pütt | Xinkai Qiu | Piotr Kozłowski | Hans Gildenast | Oliver Linnenberg | Stefan Zahn | Ryan C. Chiechi | Kirill Yu. Monakhov
Source: Chemical Communications (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Self-assembled monolayers of polyoxovanadates with phthalocyaninato lanthanide moieties on gold surfaces The two first representatives of phthalocyaninato (Pc) lanthanide-ligated polyoxovanadate cages {[V12O32(Cl)](LnPc)n}n-5 (n = 1 or 2, Ln = Yb3+) were synthesised and fully characterised. These magnetic complexes form two-dimensional self-assembled monolayers exhibiting electrical conductivity on gold substrate surfaces, as assessed by using an EGaIn tip. Lanthanide ; Monolayer ; Self-assembled monolayer ; Substrate (aquarium) ; Crystallography ; Chemistry ; Materials science ; Self-assembly ; Conductivity ; Nanotechnology ; Stereochemistry ; Organic chemistry ; Physical chemistry ; Ion Polyoxometalates: Synthesis and Applications ; Porphyrin and Phthalocyanine Chemistry ; Advanced Nanomaterials in Catalysis
Authors: Yuri Pestovsky
Source: Drug Designing & Intellectual Properties International Journal (article, 2019-06-08)
Field: Materials Science — Biomaterials

The Synthesis of Alginate Microparticles and Nanoparticles Alginate is a natural polysaccharide that is widely used as a component of pharmaceuticals and in food industry. Alginate particles can be used for encapsulation of substances with the necessity of prolonged release. They can also provide appropriate microenvironment for cells. Here the methods of the synthesis of alginate beads, micro-and nanoparticles are reviewed with special attention to the calcium alginate ones. The results from publications that did not deal with alginate particles but, to our opinion, could be applied in this field are also included in order to give an outline for possible future research. The suggested applications of the particles are mentioned as well. The two main methods for the synthesis of calcium alginate particles are internal and external gelation, but the external gelation techniques can be themselves subdivided into several subtypes. Currently, a technique being able to produce alginate nanoparticles with any desirable size does not exist. We analyze the possibilities of employing aerosolization method for this purpose. The potentials to overcome the problem of burst release of the encapsulated substances by means of cyclodextrin inclusion complexes and employing additional crosslinking agents are also discussed. The clinical application of alginate nanoparticles is still limited because of the burst release of encapsulated drugs and the poor size control of the particles formed. Further research must concentrate on overcoming these problems and on topical application of alginate particles without entering bloodstream rather than on investigation of model drug release in vitro without taking the above-mentioned problems into account. Nanoparticle ; Nanotechnology ; Microparticle ; Materials science ; Chemical engineering ; Engineering biodegradable polymer synthesis and properties ; Innovative Microfluidic and Catalytic Techniques Innovation ; Advanced Drug Delivery Systems
Authors: Stéphane Mazerat | Joséphine Lacroix | Benoît Rufino | R. Pailler
Source: Materials Today Communications (article, 2019-01-27)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Carbon derived from silicon carbide fibers, a comparative study Materials science ; Microporous material ; Composite material ; Ultimate tensile strength ; Silicon carbide ; Microstructure ; Carbide-derived carbon ; Carbon fibers ; Carbide ; Substrate (aquarium) ; Composite number ; Silicon ; Pyrolysis ; Chemical engineering ; Carbon nanofiber ; Carbon nanotube ; Metallurgy Supercapacitor Materials and Fabrication ; Advanced ceramic materials synthesis ; Graphene research and applications
Authors: Nathan Tosh | Scott Quadrelli | Graham J. Galloway | Carolyn E. Mountford
Source: Scientific Reports (article, 2019-12-11)
Field: Chemistry — Organic Chemistry

Two New Fucose-α (1–2)-Glycans Assigned In The Healthy Human Brain Taking The Number To Seven Fucosylated glycans are involved in the molecular mechanisms that underpin neuronal development, learning and memory. The capacity to study the fucose-α(1-2)-glycan residues noninvasively in the human brain, is integral to understanding their function and deregulation. Five fucose crosspeaks were assigned to fucosylated glycans using in vivo two-dimensional magnetic resonance Correlated SpectroscopY (2D L-COSY) of the brain. Recent improvements encompassed on the 3T Prisma (Siemens, Erlangen) with a 64-channel head and neck coil have allowed two new assignments. These are Fuc VI (F2:4.44, F1:1.37 ppm) and Fuc VII (F2: 4.29, F1:1.36 ppm). The Fuc VI crosspeak, close to the water resonance, is resolved due to decreased T1 noise. Fuc VII crosspeak, located between Fuc I and III, is available for inspection due to increased spectral resolution. Spectra recorded from 33 healthy men and women showed a maximum variation of up to 0.02 ppm in chemical shifts for all crosspeaks. Glycan ; Fucose ; Computational biology ; Human brain ; Computer science ; Bioinformatics ; Biology ; Neuroscience ; Genetics ; Biochemistry ; Galactose Carbohydrate Chemistry and Synthesis ; Glycosylation and Glycoproteins Research ; Lysosomal Storage Disorders Research
Authors: Kalathil K. Kartha | Felix Wendler | Tobias Rudolph | Philip Biehl | Gustavo Fernández | Felix H. Schacher
Source: Chemistry - A European Journal (article, 2019-11-12)
Field: Materials Science — Biomaterials

pH‐Responsive Side Chains as a Tool to Control Aqueous Self‐Assembly Mechanisms pH-Tunable nanoscale morphology and self-assembly mechanism of a series of oligo(p-phenyleneethynylene) (OPE)-based bolaamphiphiles featuring poly(ethylene imine) (PEI) side chains of different length and degree of hydrolysis are described. Protonation and deprotonation of the PEI chains by changing the pH alters the hydrophilic/hydrophobic balance of the systems and, in turn, the strength of intermolecular interactions between the hydrophobic OPE moieties. Low pH values (3) lead to weak interaction between the OPEs and result in spherical nanoparticles, in which aggregation follows an isodesmic mechanism. In contrast, higher pH values (11) induce deprotonation of the polymer chains and lead to a stronger, cooperative aggregation into anisotropic nanostructures. Our results demonstrate that pH-responsive chains can be exploited as a tool to tune self-assembly mechanisms, which opens exciting possibilities to develop new stimuli-responsive materials. Protonation ; Deprotonation ; Side chain ; Isodesmic reaction ; Chemistry ; Self-assembly ; Aqueous solution ; Intermolecular force ; Hydrophobic effect ; Imine ; Polymer ; Polymer chemistry ; Organic chemistry ; Molecule ; Catalysis Supramolecular Self-Assembly in Materials ; Polydiacetylene-based materials and applications ; Luminescence and Fluorescent Materials
Authors: Seokjin Moon | Yuh Hijikata | Stephan Irle
Source: Physical Chemistry Chemical Physics (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Structural transformations of graphene exposed to nitrogen plasma: quantum chemical molecular dynamics simulations Nitrogen-doped graphene (N-graphene) has been intensively studied for tailoring the electronic property of the graphene, because different nitrogen configurations influence the electronic properties of N-graphene in different ways. However, atomically precise control of the nitrogen configurations during the doping process remains a challenge in the synthesis of N-graphene. Moreover, additional structural transformations of the graphene carbon network structure as a side-effect of plasma doping are little understood and are as of yet uncontrollable. Therefore, we theoretically investigated the nitrogen doping process of graphene for a range of nitrogen atom incident kinetic energies in nonequilibrium quantum chemical molecular dynamics (QM/MD) simulations. We observed and characterized prominent configurations of N-containing graphene. In analogy to similar, earlier studies of graphene plasma hydrogenation, we observed an Eley-Rideal associative desorption mechanism during the graphene plasma nitrogenation, producing molecular nitrogen. Especially for graphitic-N (Gr-N) and Stone-Wales-defect-N (SW-N) configurations, which are frequently observed in experimental studies, we discovered two typical chemical reaction mechanisms which were well categorized by two key processes: adsorption of primary nitrogen dopant and collision with a secondary nitrogen dopant. We discussed effects of the incident nitrogen energy on the formation mechanism, and propose a method to generate of Gr-N and SW-N configurations selectively by tuning the conditions with respect to the two key formation processes. Graphene ; Molecular dynamics ; Quantum chemical ; Nitrogen ; Chemical physics ; Plasma ; Quantum ; Nanotechnology ; Dynamics (music) ; Materials science ; Chemistry ; Computational chemistry ; Physics ; Molecule ; Quantum mechanics ; Organic chemistry Graphene research and applications ; Diamond and Carbon-based Materials Research ; Carbon Nanotubes in Composites
Authors: Jonathan A. G. Cox | Rebecca C. Taylor | Alistair K. Brown | Samuel Attoe | Gurdyal S. Besra | Klaus Fütterer
Source: Acta Crystallographica Section D Structural Biology (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Crystal structure of<i>Mycobacterium tuberculosis</i>FadB2 implicated in mycobacterial β-oxidation The intracellular pathogen Mycobacterium tuberculosis is the causative agent of tuberculosis, which is a leading cause of mortality worldwide. The survival of M. tuberculosis in host macrophages through long-lasting periods of persistence depends, in part, on breaking down host cell lipids as a carbon source. The critical role of fatty-acid catabolism in this organism is underscored by the extensive redundancy of the genes implicated in β-oxidation (∼100 genes). In a previous study, the enzymology of the M. tuberculosis L-3-hydroxyacyl-CoA dehydrogenase FadB2 was characterized. Here, the crystal structure of this enzyme in a ligand-free form is reported at 2.1 Å resolution. FadB2 crystallized as a dimer with three unique dimer copies per asymmetric unit. The structure of the monomer reveals a dual Rossmann-fold motif in the N-terminal domain, while the helical C-terminal domain mediates dimer formation. Comparison with the CoA- and NAD<sup>+</sup>-bound human orthologue mitochondrial hydroxyacyl-CoA dehydrogenase shows extensive conservation of the residues that mediate substrate and cofactor binding. Superposition with the multi-catalytic homologue M. tuberculosis FadB, which forms a trifunctional complex with the thiolase FadA, indicates that FadB has developed structural features that prevent its self-association as a dimer. Conversely, FadB2 is unable to substitute for FadB in the tetrameric FadA-FadB complex as it lacks the N-terminal hydratase domain of FadB. Instead, FadB2 may functionally (or physically) associate with the enoyl-CoA hydratase EchA8 and the thiolases FadA2, FadA3, FadA4 or FadA6 as suggested by interrogation of the STRING protein-network database. Mycobacterium tuberculosis ; Dimer ; Thiolase ; Dehydrogenase ; Biology ; Biochemistry ; NAD+ kinase ; Hydrolase ; Protein structure ; Enzyme ; Chemistry ; Tuberculosis Enzyme Structure and Function ; Tuberculosis Research and Epidemiology ; Biochemical and Molecular Research
Authors: Michele Riva | Giada Franceschi | Michael Schmid | Ulrike Diebold
Source: Physical Review Research (article, 2019-10-29)
Field: Materials Science — Materials Chemistry

Epitaxial growth of complex oxide films: Role of surface reconstructions Roughening of the surface morphology and compositional inconsistency of complex-oxide films impede their use in technological applications. The authors follow the growth of SrTiO3(110) at the atomic scale, from the first stages to the development of thin films, and unveil the primary role of the atomic structure of the surface: As the deposited non stoichiometry accumulates at the surface and changes its structure, local differences in sticking produce morphological roughening. Materials science ; Epitaxy ; Oxide ; Stoichiometry ; Complex oxide ; Thin film ; Morphology (biology) ; Surface (topology) ; Atomic units ; Nanotechnology ; Surface structure ; Chemical physics ; Atomic force microscopy ; Crystallography ; Metallurgy ; Chemistry ; Physical chemistry ; Layer (electronics) ; Geometry ; Geology ; Physics Electronic and Structural Properties of Oxides ; Magnetic and transport properties of perovskites and related materials ; Ferroelectric and Piezoelectric Materials
Authors: Kosuke Nagata | Ken‐ichi Bajo | Satoru Itose | Miyuki Matsuya | Morio Ishihara | Kiichiro Uchino | Hisayoshi Yurimoto
Source: Applied Physics Express (article, 2019-07-11)
Field: Chemistry — Spectroscopy

Aberration-corrected focused ion beam for time-of-flight secondary neutral mass spectrometry A chromatic and spherical aberration corrector with liquid Ga ion metal source was developed. The aberration corrector reduced the ion probe diameter to similar to 1.5 times smaller for the Ga-69(+) beam in aberration correction mode compared with the corrector in non-aberration correction mode. The probe current at a given probe size is approximately two times larger in aberration correction mode than in non-aberration correction mode. The aberration-corrected focused ion beam yields higher lateral resolutions and higher sensitivities with lower acceleration voltage for the same acquisition time down to 10 nm with a current of 1 pA. (C) 2019 The Japan Society of Applied Physics Spherical aberration ; Chromatic aberration ; Optics ; Ion ; Beam (structure) ; Physics ; Optical aberration ; Ion beam ; Focused ion beam ; Mass spectrometry ; Chromatic scale ; Wavefront ; Lens (geology) Mass Spectrometry Techniques and Applications ; Ion-surface interactions and analysis ; Analytical chemistry methods development
Authors: M. Hafiz | M. Fairus | M. Mariatti | Mohamad Kamarol Mohd Jamil
Source: IEEE Access (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

A Comparative Study on Electrical Tree Growth in Silicone Rubber Containing Nanoalumina and Halloysite Nanoclay Recently, silicone rubber (SiR) is preferably used in high-voltage cable accessories because it offers a wide range of voltage and temperature applications and excellent electrical and mechanical properties. Furthermore, the SiR exhibits flexibility and inhibits oxidation. In this paper, the electrical tree behavior of SiR nanocomposites containing nanoalumina and halloysite nanoclay was investigated; moreover, the nanofiller concentrations were predetermined at 0 vol%, 1 vol%, 2 vol%, and 3 vol%. The electrical tree growth was observed at room temperature at 8 kVrms after tree inception voltage (TIV). The TIV and electrical tree growth in SiR nanocomposites were monitored using an online digital monitoring system, which consisted of a stereomicroscope and a digital camera. The experimental results indicated that the addition of 1 vol%-2 vol% nanoalumina in SiR composite significantly improved the TIV and electrical tree growth rate. However, the addition of 3 vol% nanoalumina in the SiR composite reduced the TIV and accelerated the electric tree growth rate. In the presence of halloysite nanoclay of approximately 3 vol%, the SiR composite showed improved TIV and electrical tree growth rate. Silicone rubber ; Halloysite ; Materials science ; Nanocomposite ; Composite material ; High-voltage cable ; Composite number ; Voltage ; Electrical engineering High voltage insulation and dielectric phenomena ; Lightning and Electromagnetic Phenomena ; Power Transformer Diagnostics and Insulation