jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Wissem Zouaghi | Laith Hussein | Mark D. Thomson | Q. Islam | N. Nicoloso | Thorsten Heinlein | Jörg Engstler | Jörg J. Schneider | Hartmut G. Roskos
Source: Lithuanian Journal of Physics (article, 2018-03-28)
Field: Materials Science — Materials Chemistry

Towards gas sensing with vertically aligned carbon nanotubes interrogated by THz radiation pulses When vertically aligned carbon nanotubes (VACNT) are exposed to gases, their dielectric properties may change by mechanisms such as doping effects or a modification of the scattering channels of the mobile charge carriers of the VACNT. This report provides first data of a study which aims at an exploration of such conductivity changes in the THz frequency regime. The test gases are NH 3 and SO 2 which are known to act as donors, respectively as acceptors when interacting with the carbon nanotubes. Our measurements confirm the doping effects. This may open the way towards gas sensors based on the VACNT interrogated by THz radiation, where the VACNTs act as an accumulation volume for certain species contained in a gas stream. Carbon nanotube ; Terahertz radiation ; Materials science ; Dielectric ; Doping ; Conductivity ; Scattering ; Radiation ; Optoelectronics ; Nanotechnology ; Carbon fibers ; Charge carrier ; Optics ; Chemistry ; Composite material ; Physics ; Physical chemistry Carbon Nanotubes in Composites ; Mechanical and Optical Resonators ; Gas Sensing Nanomaterials and Sensors
Authors: Christian J. Richard | Derek Macmillan | Graeme Hogarth
Source: Transition Metal Chemistry (article, 2018-03-24)
Field: Chemistry — Inorganic Chemistry

Microwave-assisted synthesis of cyclopentadienone iron tricarbonyl complexes: molecular structures of [{η4-C4R2C(O)C4H8}Fe(CO)3] (R = Ph, 2,4-F2C6H3, 4-MeOC6H4) and attempts to prepare Fe(II) hydroxycyclopentadienyl–hydride complexes Microwave irradiation of 1,6-diynes, RC≡C(CH2)4C≡CR, with Fe(CO)5 in dimethylether leads to the facile and clean formation of cyclopentadienone complexes [{η4-C4R2C(O)C4H8}Fe(CO)3] in good yields resulting from a [2 + 2 + 1] cycloaddition. The molecular structures of three examples (R = Ph, 2,4-F2C6H3, 4-MeOC6H4) have been obtained. The addition of HBF4 leads to the clean and reversible formation of cationic hydroxycyclopentadienyl complexes [{η5-C4R2C(OH)C4H8}Fe(CO)3][BF4]. Sequential addition of hydroxide and acid has also been carried out in an attempt to prepare hydroxycyclopentadienyl–hydride complexes. These were largely unsuccessful but in one case a Shvo-type complex with a bridging hydride was detected by 1H NMR spectroscopy. Reasons for the differing behaviour of [{η4-C4(SiMe3)2C(O)C4H8}Fe(CO)3] and the related aryl-functionalised derivatives are considered. Microwave irradiation of 1,6-diynes, RC≡C(CH2)4C≡CR, with Fe(CO)5 gives cyclopentadienone complexes [{η4-C4R2C(O)C4H8}Fe(CO)3], the molecular structures of three (R = Ph, 2,4-F2C6H3, 4-MeOC6H4) being carried out. Sequential addition of hydroxide and acid was carried out in an attempt to prepare hydroxycyclopentadienyl–hydride complexes, and while largely unsuccessful, in one case a Shvo-type complex with a bridging hydride was suggested by 1H NMR spectroscopy. Chemistry ; Hydride ; Hydroxide ; Catalysis ; Aryl ; Organometallic chemistry ; Cationic polymerization ; Medicinal chemistry ; Inorganic chemistry ; Polymer chemistry ; Organic chemistry ; Metal Asymmetric Hydrogenation and Catalysis ; Organometallic Complex Synthesis and Catalysis ; Catalysis for Biomass Conversion
Authors: Philipp Diebolder | Miguel Vazquez‐Pufleau | Nilantha Bandara | Cedric Mpoy | Ramesh Raliya | Elijah Thimsen | Pratim Biswas | Buck E. Rogers
Source: International Journal of Nanomedicine (article, 2018-11-01)
Field: Materials Science — Materials Chemistry

Aerosol-synthesized siliceous nanoparticles: impact of morphology and functionalization on biodistribution This study highlights the importance of shape and fuctionalization of siliceous NPs on organ and tumor accumulation as significant factors for biomedical applications. Biodistribution ; Surface modification ; Nanoparticle ; Materials science ; Aerosol ; Nanotechnology ; Morphology (biology) ; Chemical engineering ; Chemistry ; Organic chemistry Nanoparticles: synthesis and applications ; Laser-Ablation Synthesis of Nanoparticles ; Advanced Nanomaterials in Catalysis
Authors: Cinzia Colombo | Črtomir Podlipnik | Leonardo Lo Presti | Masahiro Niikura | Andrew J. Bennet | Anna Bernardi
Source: PLoS ONE (article, 2018-02-28)
Field: Chemistry — Organic Chemistry

Design and synthesis of constrained bicyclic molecules as candidate inhibitors of influenza A neuraminidase The rise of drug-resistant influenza A virus strains motivates the development of new antiviral drugs, with different structural motifs and substitution. Recently, we explored the use of a bicyclic (bicyclo[3.1.0]hexane) analogue of sialic acid that was designed to mimic the conformation adopted during enzymatic cleavage within the neuraminidase (NA; sialidase) active site. Given that our first series of compounds were at least four orders of magnitude less active than available drugs, we hypothesized that the new carbon skeleton did not elicit the same interactions as the cyclohexene frameworks used previously. Herein, we tried to address this critical point with the aid of molecular modeling and we proposed new structures with different functionalization, such as the introduction of free ammonium and guanidinium groups and ether side chains other than the 3-pentyl side chain, the characteristic side chain in Oseltamivir. A highly simplified synthetic route was developed, starting from the cyclopropanation of cyclopentenone and followed by an aziridination and further functionalization of the five-member ring. This allowed the efficient preparation of a small library of new bicyclic ligands that were characterized by enzyme inhibition assays against influenza A neuraminidases N1, its H274Y mutant, and N2. The results show that none of the new structural variants synthesized, including those containing guanidinium groups rather than free ammonium ions, displayed activity against influenza A neuraminidases at concentrations less than 2 mM. We conclude that the choice and positioning of functional groups on the bicyclo[3.1.0]hexyl system still need to be properly tuned for producing complementary interactions within the catalytic site. Bicyclic molecule ; Neuraminidase ; Stereochemistry ; Chemistry ; Cyclopropanation ; Active site ; Side chain ; Combinatorial chemistry ; Enzyme ; Biochemistry ; Organic chemistry Synthesis and Catalytic Reactions ; Influenza Virus Research Studies ; Chemical Synthesis and Analysis
Authors: Ming Fang | Lianshe Fu | Rute A. S. Ferreira | Luís D. Carlos
Source: Materials (article, 2018-11-12)
Field: Materials Science — Materials Chemistry

White-Light Emitting Di-Ureasil Hybrids White-light emitting materials have emerged as important components for solid state lighting devices with high potential for the replacement of conventional light sources. Herein, amine-functionalized organic-inorganic di-ureasil hybrids consisting of a siliceous skeleton and oligopolyether chains codoped with lanthanide-based complexes, with Eu<sup>3+</sup> and Tb<sup>3+</sup> ions and 4,4'-oxybis(benzoic acid) and 1,10-phenanthroline ligands, and the coumarin 1 dye were synthesized by in situ sol⁻gel method. The resulting luminescent di-ureasils show red, green, and blue colors originated from the Eu<sup>3+</sup>, Tb<sup>3+</sup>, and C1 emissions, respectively. The emission colors can be modulated either by variation of the relative concentration between the emitting centers or by changing the excitation wavelength. White light emission is achieved under UV excitation with absolute quantum yields of 0.148 ± 0.015, 0.167 ± 0.017, and 0.202 ± 0.020 at 350, 332, and 305 nm excitation, respectively. The emission mechanism was investigated by photoluminescence and UV⁻visible absorption spectroscopy, revealing an efficient energy transfer from the organic ligands to the Ln<sup>3+</sup> ions and the organic dye, whereas negligible interaction between the dopants is discerned. The obtained luminescent di-ureasils have potential for optoelectronic applications, such as in white-light emitting diodes. Materials science ; Hybrid ; White light ; White (mutation) ; Optoelectronics ; Chemistry ; Biology ; Botany Luminescence and Fluorescent Materials ; Lanthanide and Transition Metal Complexes ; Molecular Sensors and Ion Detection
Authors: Heng Li | Wen‐Juan Hao | Guigen Li | Shu‐Jiang Tu | Bo Jiang
Source: Frontiers in Chemistry (article, 2018-12-04)
Field: Chemistry — Organic Chemistry

Fe(III)-Catalyzed Bicyclization of Yne-Allenones With Indoles for the Atom-Economic Synthesis of 3-Indolyl Cyclobutarenes A new Fe(III)-catalyzed bicyclization reaction of yne-allenones with indoles has been established, enabling the direct construction of cyclobuta[<i>a</i>]naphthalen-4-ols with an all-carbon quaternary center in good to excellent yields. This reaction was performed by using low-cost FeCl<sub>3</sub> as the catalyst and EtOH as the environmentally benign solvent, providing a green protocol for constructing the cyclobutarene framework with a high degree of atom economy and functional group compatibility. The reaction mechanism was proposed to proceed through a [2 + 2] cycloaddition/1,6-conjugate addition cascade. Catalysis ; Atom economy ; Conjugate ; Chemistry ; Atom (system on chip) ; Combinatorial chemistry ; Carbon atom ; Functional group ; Cycloaddition ; Cascade reaction ; Solvent ; Compatibility (geochemistry) ; Medicinal chemistry ; Organic chemistry ; Mathematics ; Materials science ; Computer science ; Polymer ; Parallel computing Catalytic Alkyne Reactions ; Catalytic C–H Functionalization Methods ; Cyclopropane Reaction Mechanisms
Authors: Elena Lestini | Codrin Andrei | Dominic Zerulla
Source: PLoS ONE (article, 2018-04-17)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Linear self-assembly and grafting of gold nanorods into arrayed micrometer-long nanowires on a silicon wafer via a combined top-down/bottom-up approach Macroscopically long wire-like arrangements of gold nanoparticles were obtained by controlled evaporation and partial coalescence of an aqueous colloidal solution of capped CTAB-Au nanorods onto a functionalised 3-mercaptopropyl trimethoxysilane (MPTMS) silicon substrate, using a removable, silicon wafer with a hydrophobic surface that serves as a "handrail" for the initial nanorods' linear self-assembly. The wire-like structures display a quasi-continuous pattern by thermal annealing of the gold nanorods when the solvent (i.e. water) is evaporated at temperatures rising from 20°C to 140°C. Formation of both single and self-replicating parallel 1D-superstructures consisting of two or even three wires is observed and explained under such conditions. Nanorod ; Silicon ; Wafer ; Materials science ; Nanotechnology ; Self-assembly ; Aqueous solution ; Nanowire ; Substrate (aquarium) ; Annealing (glass) ; Coalescence (physics) ; Dewetting ; Chemical engineering ; Nanoparticle ; Colloidal gold ; Chemistry ; Composite material ; Thin film ; Optoelectronics ; Organic chemistry Gold and Silver Nanoparticles Synthesis and Applications ; Nanomaterials and Printing Technologies ; Quantum Dots Synthesis And Properties
Authors: Attila Bonyár | Zsanett Izsold | Alexandra Borók | István Csarnovics | L. Himics | M. Vereš | Gábor Harsányi
Source:  (article, 2018-11-26)
Field: Materials Science — Electronic, Optical and Magnetic Materials

PDMS-Au/Ag Nanocomposite Films as Highly Sensitive SERS Substrates Polydimethylsiloxane (PDMS)–gold/silver nanoparticle composite films were synthetized in situ by using a simple method, which is based on the reduction of chloroauric acid (HAuCl4) or silver nitrate solution (AgNO3) by the PDMS membrane. A method to monitor the development of the plasmonic absorbance peak in situ (during the synthesis of the nanoparticles) is introduced in order to provide a convenient way to investigate the effect of the technological parameters on the position of the resulting peak. The resulting composite films were tested as SERS substrates at two excitation wavelengths (488 nm, 785 nm) and the preliminary results indicate that they are promising candidates for this application, with high sensitivities accompanied by cheap fabrication costs. Chloroauric acid ; Polydimethylsiloxane ; Materials science ; Silver nitrate ; Silver nanoparticle ; Nanocomposite ; Absorbance ; Fabrication ; Plasmon ; Composite number ; Nanoparticle ; Nanotechnology ; Plasmonic nanoparticles ; HYDROSOL ; Chemical engineering ; Colloidal gold ; Optoelectronics ; Composite material ; Chemistry ; Chromatography Gold and Silver Nanoparticles Synthesis and Applications ; Laser-Ablation Synthesis of Nanoparticles ; Quantum Dots Synthesis And Properties
Authors: Majdi Mansouri
Source: Acta Physica Polonica A (article, 2018-05-01)
Field: Materials Science — Materials Chemistry

Effects of Vacancy-Defected, Dopant and the Adsorption of Water upon Mn<sub>2</sub>O<sub>3</sub> and Mn<sub>3</sub>O<sub>4</sub> (001) Surfaces: A First-Principles Study In this study, a first-principles study using the spin-polarized density functional theory approach within corrected functional was carried out to investigate the electronic features of manganese oxide surfaces under three situations of (a) cation vacancy, (b) intercalation of multi-and univalent ions, and (c) adsorption of a water molecule upon the surface as catalytic performance. The possibility of obtaining the significant absolute magnetic momentum phases from native defects in orthorhombic structures of Mn2O3 and Mn3O4 (001) surface is explored, whereas Mn vacancy provides a transition from the insulating phase into a metal-like nature and modifies the electronic transport. Moreover, bandgap engineering via impurity intercalation has been explored. Ca +2 and Al +3 intercalations have manifested substantial attributes and explain the experimental results as efficient conducting system and catalytic activity. Furthermore, the adsorption of one water molecule and the most stable configuration, adsorption energies and electronic properties were thoroughly discussed. Accordingly, it was explored that H2O: Mn2O3 and Mn3O4 exhibit suitable parameters as efficient catalytic synthesis. Vacancy defect ; Dopant ; Adsorption ; Materials science ; Crystallography ; Physical chemistry ; Mineralogy ; Chemistry ; Doping Magnesium Oxide Properties and Applications ; Electrical and Thermal Properties of Materials ; Magnetic Properties and Synthesis of Ferrites
Authors: Xi Chen | Muthukumaran Venkatachalapathy | Leif Dehmelt | Yao‐Wen Wu
Source: Angewandte Chemie (article, 2018-07-26)
Field: Materials Science — Materials Chemistry

Multidirectional Activity Control of Cellular Processes by a Versatile Chemo‐optogenetic Approach Abstract The spatiotemporal dynamics of proteins or organelles plays a vital role in controlling diverse cellular processes. However, acute control of activity at distinct locations within a cell is challenging. A versatile multidirectional activity control (MAC) approach is presented, which employs a photoactivatable system that may be dimerized upon chemical inducement. The system comprises second‐generation SLF*‐TMP (S*T) and photocaged NvocTMP‐Cl dimerizers; where, SLF*‐TMP features a synthetic ligand of the FKBP(F36V) binding protein, Nvoc is a caging group, and TMP is the antibiotic trimethoprim. Two MAC strategies are demonstrated to spatiotemporally control cellular signaling and intracellular cargo transport. The novel platform enables tunable, reversible, and rapid control of activity at multiple compartments in living cells. Optogenetics ; FKBP ; Chemistry ; Organelle ; Intracellular ; Biophysics ; Cell biology ; Biology ; Biochemistry ; Neuroscience Photochromic and Fluorescence Chemistry ; Photoreceptor and optogenetics research ; Light effects on plants
Authors: Saule Zholdayakova | Ryota Gemma | Haru-Hisa Uchida | Masashi Sato | Yoshihito Matsumura
Source: e-Journal of Surface Science and Nanotechnology (article, 2018-06-20)
Field: Materials Science — Materials Chemistry

Mechanical Composition Control for Ti-Based Hydrogen Storage Alloys Hydrogen absorbing alloys have attracted great attention because they are a safe and efficient media for transporting hydrogen energy. AB, AB2, AB5, and A2B-type hydrogen storage compounds and related substituted multi-component alloys have been proposed. In general, titanium-based alloys are among the most promising materials for hydrogen storage. Among the various available types of metal hydrides, AB2 type Ti-Cr-based alloys are the most promising candidates. In particular, there have been many methods for improving the hydrogen sorption properties. One of them is to prepare hydrogen absorbing alloys by mechanical alloying (MA). MA also enables synthesizing various non-equilibrium alloys and has been widely applied to modify properties of hydrogen storage alloys. Thus, MA is possibly the best way for mechanical composition control and mass production of various hydrogen storage alloys. Hydrogen storage ; Composition (language) ; Materials science ; Metallurgy ; Alloy ; Art Hydrogen Storage and Materials ; Nuclear Materials and Properties ; Titanium Alloys Microstructure and Properties
Authors: Xilun Xiang | Haiguang Liu
Source: BMC Bioinformatics (article, 2018-03-16)
Field: Chemistry — Spectroscopy

IDPM: an online database for ion distribution in protein molecules The spatial distribution of ions around amino acids is documented and analyzed. The statistics can be useful for identifying ion types for a given site in biomolecules, and can be potentially used in ion position prediction for given structures. Computer science ; Computational biology ; Database ; DNA microarray ; Biology ; Genetics ; Gene expression ; Gene Mass Spectrometry Techniques and Applications ; Protein Structure and Dynamics ; Enzyme Structure and Function
Authors: R. Clapham Paul | Shramana Chatterjee | Seema Nath | U. Sen
Source: Scientific Reports (article, 2018-11-12)
Field: Materials Science — Materials Chemistry

Large-scale conformational changes and redistribution of surface negative charge upon sugar binding dictate the fidelity of phosphorylation in Vibrio cholerae fructokinase Fructokinase (FRK) catalyzes the first step of fructose metabolism i.e., D-fructose to D-fructose-6-phosphate (F6P), however, the mechanistic insights of this reaction are elusive yet. Here we demonstrate that the putative Vibrio cholerae fructokinase (VcFRK) exhibit strong fructose-6-kinase activity allosterically modulated by K<sup>+</sup>/Cs<sup>+</sup>. We have determined the crystal structures of apo-VcFRK and its complex with fructose, fructose-ADP-Ca<sup>2+</sup>, fructose-ADP-Ca<sup>2+</sup>-BeF<sub>3</sub><sup>-</sup>. Collectively, we propose the catalytic mechanism and allosteric activation of VcFRK in atomistic details explaining why K<sup>+</sup>/Cs<sup>+</sup> are better activator than Na<sup>+</sup>. Structural results suggest that apo VcFRK allows entry of fructose in the active site, sequester it through several conserved H-bonds and attains a closed form through large scale conformational changes. A double mutant (H108C/T261C-VcFRK), that arrests the closed form but unable to reopen for F6P release, is catalytically impotent highlighting the essentiality of this conformational change. Negative charge accumulation around ATP upon fructose binding, is presumed to redirect the γ-phosphate towards fructose for efficient phosphotransfer. Reduced phosphotransfer rate of the mutants E205Q and E110Q supports this view. Atomic resolution structure of VcFRK-fructose-ADP-Ca<sup>2+</sup>-BeF<sub>3</sub><sup>-</sup>, reported first time for any sugar kinase, suggests that BeF<sub>3</sub><sup>-</sup> moiety alongwith R176, Ca<sup>2+</sup> and 'anion hole' limit the conformational space for γ-phosphate favoring in-line phospho-transfer. Vibrio cholerae ; Fructokinase ; Redistribution (election) ; Phosphorylation ; Chemistry ; Sugar ; Biochemistry ; Biophysics ; Microbiology ; Biology ; Cell biology ; Bacteria ; Genetics Enzyme Structure and Function ; Diet, Metabolism, and Disease ; Protein Structure and Dynamics
Authors: Marcia Roy | Oksana Sorokina | C. Mclean | Silvia Tapia‐González | Javier DeFelipe | J. Douglas Armstrong | Seth G. N. Grant
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2018-07-13)
Field: Chemistry — Spectroscopy

Regional diversity in the postsynaptic proteome of the mouse brain Abstract The proteome of the postsynaptic terminal of excitatory synapses comprises over one thousand proteins in vertebrate species and plays a central role in behavior and brain disease. The brain is organized into anatomically distinct regions and whether the synapse proteome differs across these regions is poorly understood. Postsynaptic proteomes were isolated from seven forebrain and hindbrain regions in mice and their composition determined using proteomic mass spectrometry. Seventy-four percent of proteins showed differential expression and each region displayed a unique compositional signature. These signatures correlated with the anatomical divisions of the brain and their embryological origins. Biochemical pathways controlling plasticity and disease, protein interaction networks and individual proteins involved with cognition all showed differential regional expression. Combining proteomic and connectomic data shows that interconnected regions have specific proteome signatures. Diversity in synapse proteome composition is key feature of mouse and human brain structure. Proteome ; Postsynaptic potential ; Forebrain ; Postsynaptic density ; Biology ; Neuroscience ; Proteomics ; Synapse ; Computational biology ; Central nervous system ; Bioinformatics ; Genetics ; Receptor ; Gene Advanced Proteomics Techniques and Applications ; Alzheimer's disease research and treatments ; Metabolomics and Mass Spectrometry Studies
Authors: Grzegorz Chimczak | Karol Bartkiewicz | Zbigniew Ficek | Ryszard Tanaś
Source: Scientific Reports (article, 2018-09-27)
Field: Materials Science — Materials Chemistry

Creating a switchable optical cavity with controllable quantum-state mapping between two modes We describe how an ensemble of four-level atoms in the diamond-type configuration can be applied to create a fully controllable effective coupling between two cavity modes. The diamond-type configuration allows one to use a bimodal cavity that supports modes of different frequencies or different circular polarisations, because each mode is coupled only to its own transition. This system can be used for mapping a quantum state of one cavity mode onto the other mode on demand. Additionally, it can serve as a fast opening high-Q cavity system that can be easily and coherently controlled with laser fields. Coupling (piping) ; Mode (computer interface) ; Optical cavity ; Laser ; State (computer science) ; Quantum Diamond and Carbon-based Materials Research ; Quantum optics and atomic interactions ; Mechanical and Optical Resonators