jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Alan G. Hinnebusch | Peihua Yuan | Paul K. Herman | Brian J. Dewar | Naseem A. Gaur | Max Wolpert | Carl J. Mousley | Aaron H. Nile | Stephen J. Deminoff | Vytas A. Bankaitis | Kyle Trettin | Jeffrey M. Macdonald
Source: UNC Libraries (article, 2020-11-01)
Field: Materials Science — Materials Chemistry

A Sterol-Binding Protein Integrates Endosomal Lipid Metabolism with TOR Signaling and Nitrogen Sensing Kes1, and other oxysterol binding protein (OSBP) superfamily members, are involved in membrane and lipid trafficking through trans-Golgi network (TGN) and endosomal systems. We demonstrate that Kes1 represents a sterol-regulated antagonist of TGN/endosomal phosphatidylinositol-4-phosphate signaling. This regulation modulates TOR activation by amino acids, and dampens gene expression driven by Gcn4; the primary transcriptional activator of the general amino acid control regulon. Kes1-mediated repression of Gcn4 transcription factor activity is characterized by nonproductive Gcn4 binding to its target sequences, involves TGN/endosome-derived sphingolipid signaling, and requires activity of the cyclin-dependent kinase 8 (CDK8) module of the enigmatic ‘large Mediator’ complex. These data describe a pathway by which Kes1 integrates lipid metabolism with TORC1 signaling and nitrogen sensing. Endosome ; Lipid metabolism ; Chemistry ; Sterol ; Biochemistry ; Metabolism ; Cell biology ; Biology ; Cholesterol ; Receptor Porphyrin and Phthalocyanine Chemistry ; Cholesterol and Lipid Metabolism ; Retinal Diseases and Treatments
Authors: Luis Nóvoa | Laura Trulli | Alejandro Parra | Mariola Tortosa
Source: CHIMIA International Journal for Chemistry (article, 2020-11-25)
Field: Chemistry — Organic Chemistry

Copper, Boron and Vinyl Epoxides: from 1,4-Diols to Cyclopropylboronates Herein we describe the reactivity found between vinyl epoxides and catalytically generated copper-boryl complexes. By tuning the substituents of the alkene and/or the reaction conditions, 1,4-diols, allylic alcohols or cyclopropylboronates can be prepared. The stereochemical information of the vinyl epoxide is transferred to the products with high levels of stereocontrol. Epoxide ; Alkene ; Allylic rearrangement ; Boron ; Chemistry ; Copper ; Reactivity (psychology) ; Organic chemistry ; Diol ; Polymer chemistry ; Catalysis Organoboron and organosilicon chemistry ; Asymmetric Hydrogenation and Catalysis ; Asymmetric Synthesis and Catalysis
Authors: Byeong Guk Jeong | Jun Hyuk Chang | Donghyo Hahm | Seunghyun Rhee | Myeongjin Park | Sohoo Lee | Youngdu Kim | Doyoon Shin | Jeong Woo Park | Changhee Lee | Doh C. Lee | Kyoungwon Park | E. H. Hwang | Wan Ki Bae
Source: Research Square (preprint, 2020-12-10)
Field: Materials Science — Materials Chemistry

Controlling potential landscape of heterostructured nanocrystals with interfacial polarization Abstract The potential profile and the energy level offset of core/shell heterostructured nanocrystals ( h -NCs) determine the photophysical properties and the charge transport characteristics of h -NC solids. However, limited material choices for heavy metal-free III-V/II-VI h -NCs pose challenges in comprehensive control of the potential profile. Herein, we present an unprecedented approach to such control by steering dipole moments at the interface of III-V/II-VI h -NCs. The controllable heterovalency at the interface is responsible for interfacial dipole moments that result in the vacuum-level shift, providing an additional knob for the control of optical and electrical characteristics of h -NCs. We capitalize on the atomic precision with which to synthesize h -NCs by correlating interfacial dipole moments to photochemical stability and optoelectronic performance of resulting h -NCs. Nanocrystal ; Polarization (electrochemistry) ; Materials science ; Nanotechnology ; Optoelectronics ; Chemistry ; Physical chemistry Quantum Dots Synthesis And Properties ; Chalcogenide Semiconductor Thin Films ; Copper-based nanomaterials and applications
Authors: Zixiang Fang | Maheshika SK Wanigasekara | Akop Yepremyan | Brandon Lam | Pawan Thapa | Frank W. Foss | Saiful M. Chowdhury
Source: ChemRxiv (preprint, 2020-12-17)
Field: Chemistry — Spectroscopy

A Mass Spectrometry-Cleavable N-Terminal Tagging Strategy for System-Level Protease Activity Profiling Proteolysis is one of the most important protein post-translational modifications (PTMs) that influences the functions, activities, and structures of nearly all proteins during their lifetime. This irreversible PTM is regulated and catalyzed by proteases through hydrolysis reaction in the process of protein maturation or degradation. The identification of proteolytic substrates is pivotal in understanding the specificity of proteases and the physiological role of proteolytic process. However, tracking these biological phenomena in native cells is very difficult due to their low abundances. Currently, no efficient methods are available to identify proteolytic products from large-scale samples. To facilitate the targeted identification of low-abundant proteolytic products, we devise a strategy incorporating a novel biotinylated reagent PFP (pentafluorophenyl)-Rink-biotin to specifically target, enrich and identify proteolytic N-terminus. Within the PFP-Rink-biotin reagent, an MS-cleavable feature is designed to assist in the unambiguous confirmation of the enriched proteolytic N-termini. This is the first reported study of identifying proteolytic N-terminus by MS-cleavable feature widely adopted in studying low-abundant protein PTMs and cross-linking/MS. The proof-of-concept study was performed with multiple standard proteins whose N-terminus were successfully modified, enriched and identified by a signature ion (SI) in the MS/MS fragmentation, along with the determination of N-terminal peptide sequences by multistage tandem MS of the complementary fragment generated after the cleavage of MS-cleavable bond. For large-scale application, the enrichment and identification of protein N-termini from Escherichia.coli cells were demonstrated along with a bioinformatics workflow. We believe this method can be very useful to locate proteolytic products in native cellular environment with high confidence.&lt;br&gt; Proteases ; Proteolysis ; Chemistry ; Biotinylation ; Protease ; Biochemistry ; Proteolytic enzymes ; Biotin ; Tandem mass spectrometry ; Proteomics ; Computational biology ; Mass spectrometry ; Enzyme ; Biology ; Chromatography ; Gene Advanced Proteomics Techniques and Applications ; Peptidase Inhibition and Analysis ; Machine Learning in Bioinformatics
Authors: Pedro Augusto Machado Vitor
Source: Lume (Universidade Federal do Rio Grande do Sul) (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Nanoferritas mistas (Co1-yNiy)Fe2O4 : síntese via sol-gel e sua caracterização microestrutural e de propriedades magnéticas e ópticas em função da distribuição catiônica Nanoferritas mistas têm sido cada vez mais utilizadas em aplicações funcionais devido às suas propriedades, principalmente as magnéticas, associadas às altas energias de superfície. Este trabalho estuda uma série de nanoferritas mistas de níquel e cobalto (Co1-yNiy)Fe2O4, com y = 0; 0,25; 0,5; 0,75 e 1,0, com o objetivo de ajustar suas propriedades magnéticas e ópticas através da manipulação da composição. A síntese foi conduzida pelo método sol-gel a partir da reação nitrato/citrato associada a diferentes condições de tratamento térmico, o que proporcionou um fácil controle da distribuição do cátion nos sítios tetraédricos (A) e octaédricos (B) da estrutura cristalina. Os resultados de DRX confirmaram uma fase espinélio para todas as amostras de ferritas. Ensaios de MET e BET confirmaram a dimensão nanométrica das partículas obtidas (11 - 16 nm). As espectroscopias Raman e Mössbauer permitiram determinar o grau de inversão das amostras, estimando a população de cátions Fe3+ nos sítios A e B. A ferrita de níquel é organizada em uma estrutura de espinélio inverso com comportamento magnético macio (Hc = 83 Oe; Ms = 41,72 emu.g-1), enquanto a amostra de ferrita de cobalto (CoFe2O4) mostra um comportamento magnético duro (Hc = 894 Oe; Ms = 51,13 emu.g-1) em um retículo parcialmente inverso. O considerável endurecimento magnético com a substituição de Ni2+ por Co2+ é explicado considerando o aumento da energia da anisotropia e a diminuição do grau de inversão, que também elevam a magnetização de saturação pelo aumento líquido nos momentos magnéticos. No comportamento semicondutor, a inversão parcial das amostras ricas em cobalto introduz estados de energia que reduziram drasticamente o band gap. Os valores calculados de Eg variaram entre 1,86 eV para a ferrita de níquel e 1,27 eV para a de cobalto. Este estudo é um passo à frente no sentido de melhorar a compreensão dos mecanismos de inversão envolvidos no ajuste fino de materiais ferrimagnéticos. Physics Magnetic Properties and Synthesis of Ferrites ; Pigment Synthesis and Properties
Authors: Jérôme Waser | Stefano Nicolai | Stephanie G. E. Amos
Source: ChemRxiv (preprint, 2020-06-09)
Field: Chemistry — Organic Chemistry

Accessing 1,2-Amino Alcohols and Diols through Photocatalytic Anti-Markovnikov Difunctionalisation of Ene-Carbamates and Enol Ethers We report an atom-economical 1,2-oxyalkynylation of ene-carbamates and enol ethers based on the use of Ethynyl BenziodoXolone (EBX) as dual reagents for alkyne and oxygen transfer. The reaction occurs at room temperature under blue LED irradiation using an organic dye as a photocatalyst. A broad variety of 1-alkynyl-1,2-amino-alcohol and 1-alkynyl-1,2-diol scaffolds were obtained in up to 89% yield with anti-Markovnikov regioselectivity. The reaction is speculated to proceed via oxidation of the double bond to give a radical cation intermediate, enabling the selective difunctionalization of electron-rich alkenes. Markovnikov's rule ; Chemistry ; Enol ; Ene reaction ; Regioselectivity ; Yield (engineering) ; Photocatalysis ; Reagent ; Double bond ; Organic chemistry ; Diol ; Alcohol ; Photoinduced electron transfer ; Medicinal chemistry ; Alkyne ; Photochemistry ; Combinatorial chemistry ; Electron transfer ; Catalysis ; Materials science Sulfur-Based Synthesis Techniques ; Radical Photochemical Reactions ; Catalytic C–H Functionalization Methods
Authors: Serap Aksu
Source:  (article, 2020-08-20)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Surface enhanced vibrational spectroscopy using ultra narrow-band perfect absorber In this work, we present a narrow-band (sub-100 cm<sup>-1</sup> ) and multi-band metamaterial perfect absorber operating in the mid-IR frequency regime for analysis of biomolecules with vibrational spectroscopy. The presented perfect absorber is based on multi-layer metamaterial plasmonic nanoantennas. We used numerical and experimental work to fine tune the parameters of the PA and control its spectral response. The suggested PA system provides high absorbance values (100%) in the mid-IR region and near-field enhancement factor of 10<sup>3</sup> at the corresponding resonance values. The experimental results are well agreeing the numerical results. The working principle of the presented perfect absorption can be both explained by impedance matching and critical coupling phenomenon. The fabricated PA shows strong narrow band resonance and all the resonance energy could be transferred to thin films (10 nm) for higher sensitivity. In addition, PA shows multi-band resonances within the mid-IR region, thus it can be effectively used for simultaneously detecting the different biomolecular fingerprints. In this sense, we experimentally observed absorption of carbonyl (C=O) and asymmetric methyl (-CH<sub>3</sub>) stretching bands of thin polymethyl methacrylate (PMMA) film on the narrow band resonance of PA. Materials science ; Resonance (particle physics) ; Absorbance ; Spectroscopy ; Absorption (acoustics) ; Metamaterial ; Optoelectronics ; Absorption band ; Metamaterial absorber ; Infrared spectroscopy ; Absorption spectroscopy ; Plasmon ; Dipole ; Optics ; Molecular physics ; Analytical Chemistry (journal) ; Atomic physics ; Chemistry ; Physics ; Tunable metamaterials Metamaterials and Metasurfaces Applications ; Plasmonic and Surface Plasmon Research ; Advanced Antenna and Metasurface Technologies
Authors: Yujie Liu | Alexander Wiorek | Gastón A. Crespo | María Cuartero
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2020-09-25)
Field: Chemistry — Electrochemistry

Spectroelectrochemical Evidence of Interconnected Charge and Ion Transfer in Ultrathin Membranes Modulated by a Redox Conducting Polymer Previous publications have demonstrated the tuning of ion-<br> transfer (IT) processes across ion-selective membranes (ISMs) with<br> thicknesses in the nanometer order by modulating the oxidation state of a<br> film of a conducting polymer, such as poly(3-octylthiophene) [POT], that is<br> in back-side contact. Attempts on the theoretical description of this charge<br> transfer (CT)−IT system have considered the Nernst equation for the CT,<br> while there is no empirical evidence confirming this behavior. We present<br> herein the first experimental characterization of the CT in POT films<br> involved in different CT−IT systems. We take advantage of the absorbance<br> change in the POT film while being oxidized, to monitor the CT linked to<br> nonassisted and assisted ITs at the sample−ISM interface, from one to three ionophores, therefore promoting a change in the nature and number of the ITs. The CT is visualized as an independent sigmoid in different potential ranges according to the assigned IT. Herein, we have proposed a simple calculation of the empirical CT utilizing the mathematical Sigmoidal−Boltzmann model. The identification of the physical meaning of the mathematical definition of CT opens up new possibilities for the design of sensors with superior analytical features (mainly in terms of selectivity) and the calculation of apparent binding constants in the ISM. Redox ; Membrane ; Materials science ; Ion ; Charge (physics) ; Polymer ; Conductive polymer ; Chemical engineering ; Nanotechnology ; Chemistry ; Composite material ; Engineering ; Physics ; Organic chemistry Electrochemical Analysis and Applications ; Electrochemical sensors and biosensors ; Conducting polymers and applications
Authors: Peter Tieu | Chaitanya Gadre | Wenpei Gao | Xingxu Yan | Djawhar Ferrah | Mu‐Qing Li | Zhengtao Xu | Xiaoqing Pan
Source: Microscopy and Microanalysis (article, 2020-07-30)
Field: Chemistry — Inorganic Chemistry

In Situ Observations of Post-Synthesis Modification of a Metal-Organic Framework Using Atomic Resolution S/TEM and EELS In situ ; Materials science ; Metal ; Resolution (logic) ; Nanotechnology ; Chemistry ; Metallurgy ; Computer science ; Organic chemistry ; Artificial intelligence Metal-Organic Frameworks: Synthesis and Applications ; Machine Learning in Materials Science ; X-ray Diffraction in Crystallography
Authors: L. Wang
Source: Leiden Repository (Leiden University) (article, 2020-02-25)
Field: Chemistry — Organic Chemistry

Reagent Controlled Synthesis of 1,2-cis-Oligosaccharides &lt;table&gt;&lt;tbody&gt;&lt;tr&gt;&lt;td&gt;&lt;p&gt;This Thesis describes a strategy to synthesize 1,2-cis-oligosaccharides modulated by additives, such as dimethylformamide (DMF), triphenylphosphine oxide (Ph3P=O) and N-methyl(phenyl)formamide (MPF), using building blocks that carry solely benzyl type protecting groups and are therefore of uniform reactivity. These three additives were used for different classes of donor-acceptor combinations. The additive DMF was mainly used to modulate glycosylations of per-benzylated glucosyl donors and secondary alcohol acceptors. The TMSI-Ph3P=O condition was used to glycosylate the more reactive primary alcohol acceptors. The MPF additive, which forms less stable anomeric imidinium ion intermediates than DMF, was used for donors that are somewhat less reactive, such as those in the 2-azido-2-deoxy series.&lt;/p&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/tbody&gt;&lt;/table&gt; Chemistry ; Alcohol ; Anomer ; Dimethylformamide ; Reagent ; Nucleophile ; Reactivity (psychology) ; Benzyl alcohol ; Organic chemistry ; Formamide ; Electrophile ; Combinatorial chemistry ; Catalysis ; Medicinal chemistry ; Polymer chemistry ; Solvent Carbohydrate Chemistry and Synthesis ; Glycosylation and Glycoproteins Research ; Chemical Synthesis and Analysis
Authors: Alejandro Enrique Plaza
Source: CINECA IRIS Institutial Research Information System (University of Genoa) (article, 2020-03-20)
Field: Materials Science — Materials Chemistry

FABRICATION and CHARACTERIZATION of BIDIMENSIONAL ELECTRONIC GAS (2DEG) in ZnO BASED HETEROSTRUCTURES Spintronics and High Electronic Mobility Transistors (HEMTs) are active frontiers in the development of electronic devices. For their development, Diluted Magnetic Semiconductors (DMS) and heterostructures hosting Two Dimensional Electronic Gas (2DEG) are required. MBE has become into the state of the art technique to prepare ZnO based heterostructures, surpassing PLD limitations. However, the former has a much more complex operation and higher costs. In order to improve the quality of ZnO based heterostructures at bounded costs, a low oxidative MBE process was studied. The aim of the present thesis is double: first, it intends to make a contribution to the knowledge of the non conventional low oxidative MBE production of ZnO heterostructures. In particular we wanted to assess its feasibility and understand the growth mechanism. Second, this thesis intends to make specific contributions to the physics of electric transport in such heterostructures, namely Electric Field modulated Magnetoresistance and 2DEG Magnetic Field Effective Mass Enhancement. For the first objective, 142 MgO/ZnO heterostructures were grown on sapphire on a home-made MBE in low oxidative conditions. An extensive characterization of the sample set by RHEED, AFM, XRD, SEM, EDS and Transport measurement was carried out. The analysis of the data gathered made it possible to identify different growth stages of the ZnO structures. They were mainly discussed in terms of misfit accommodation. The results suggest a complex process with interlinked steps, in which subtle transformations take place. For the second objective, Field Effect devices were produced by depositing Co:ZnO/STO heterostructures by PLD. After XRD, AFM, TEM and magnetic characterization, transport measurements were carried out. The magnetic scattering was studied by appropriate model fitting and discussed in terms of percolation of Bounded Magnetic Polarons (BMP). The results suggest free charge carrier mediated magnetic polarization of Co:ZnO. Next, a 2DEG hosting Mg:ZnO/ZnO heterostructure was deposited by PLD. Transport measurements showed complex quantum oscillations. The simultaneous model fitting for all temperatures showed magnetic field effective mass enhancement. The results suggest band non-parabolicity and electron-electron correlation as possible causes. Heterojunction ; Characterization (materials science) ; Fabrication ; Optoelectronics ; Materials science ; Nanotechnology ; Chemistry ZnO doping and properties
Authors: Esmaeel Fatahian | Ebrahim Hosseini | Hossein Fatahian
Source: International Journal of Engineering Technology and Sciences (review, 2020-09-23)
Field: Materials Science — Materials Chemistry

A review on recent research studies on vibration analysis of fluid-conveying nanotubes Nanotube (such as carbon and boron nitride nanotubes) is a key component of modern technology applications of nanostructures due to their unique mechanical, electrical, and physical characteristics such as high elasticity modulus, suitable heat transfer, and electrical conductivity. Carbon and boron nitride nanotubes are among the promising choices in nano-fluidic, gas storage, and drug delivery systems due to their hollow cylindrical shape and appropriate chemical, mechanical, and physical properties. Thermal vibration assessment should be conducted on fluid-conveying carbon nanotubes since the effect of thermal fluctuations on the mechanical characteristics of nanostructure are significant. Previous studies have revealed that when thermal vibration is taken into account, quantum effects can become extremely important in nanoscale electronics and structures. Hence, the present review focuses mostly on previous work on fluid-conveying nanotubes and the dynamical characteristics of size-dependent vibration and non-local strain gradient theory of fluid-conveying nanotubes. Furthermore, a special effort is made to address recent and rare investigations on the vibration of fluid-conveying nanotubes in thermal environment, as well as thermal vibration concerns of carbon nanotubes. Carbon nanotube ; Materials science ; Carbon nanotube actuators ; Boron nitride ; Nanotechnology ; Vibration ; Nanostructure ; Thermal conductivity ; Mechanical properties of carbon nanotubes ; Nanotube ; Thermal ; Composite material ; Heat transfer ; Mechanics ; Thermodynamics Nonlocal and gradient elasticity in micro/nano structures ; Carbon Nanotubes in Composites ; Composite Structure Analysis and Optimization
Authors: 崇 町田
Source: Hokkaido University Collection of Scholarly and Academic Papers (Hokkaido University) (article, 2020-09-25)
Field: Materials Science — Materials Chemistry

Large Structural Change of Aggregation-Induced Emission (AIE) Molecules in the Excited State Chapter I 9Considering RIR process in the AIE behavior, researchers have focused on induction of the strong luminescence of AIEgens without aggregation.Cyclization-induced emission (CIE), reported by Shinkai et al., is one of the most noteworthy researches.In CIE system, when TPE derivative having zinc dipicolylamine groups interacts with carboxylic acid in a homogeneous buffer solution, it become emissive. 32 Wu and coworkers also reported CIE-like behavior, in which bisurea-tethering TPE showed intense luminescence under the presence of anions in a homogeneous solution. 33 Furthermore, Kokado et al. made network polymers using AIEgens as a crosslinker. 34,35 In network polymers, AIEgens emit strong luminescence even in the quite low concentration, but the luminescence was quenched as the polymer swelled.Above examples seem to support the RIR process, but some AIEgens do not have rotator such as free phenyl rings, and the RIR process is not applicable to such AIEgens.Therefore, more broadly defined words restriction of intramolecular vibration (RIV) and restriction of intramolecular motion (RIM) have come to be used. Aggregation-induced emission ; Excited state ; Molecule ; Chemistry ; State (computer science) ; Fluorescence ; Physics ; Computer science ; Atomic physics ; Quantum mechanics ; Algorithm Luminescence and Fluorescent Materials ; Photochemistry and Electron Transfer Studies ; Molecular Junctions and Nanostructures