jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Abgeena Shabir | Abid Abid | Poonam Sehrawat | C. Julien | Saurav Islam
Source: Nanotechnology (article, 2020-07-10)
Field: Materials Science — Materials Chemistry

Reversible synthesis of GO: Role of differential bond structure transformation in fine-tuning photodetector response The controlled modification of graphene's electronic band structure poses serious challenges. In the present work, we study the effect of sp <sup>2</sup> cluster size variation on the electronic band gap and photoconductive properties of reduced graphene oxide (RGO). This is achieved by performing reversible functionalization of RGO with oxygen species. The reversible functionalization of RGO results in its partial transformation to graphene oxide (GO) so that the size of the sp <sup>2</sup> clusters within the sp <sup>3</sup> matrix varies, thereby affecting the π-π* band structure and photoconductive properties. The study reveals: (1) incremental creation/elimination of oxygenated surface bonds' related energy states within the π-π<sup>*</sup> band; (2) customized tuning of the sp <sup>2</sup>/sp <sup>3</sup> ratio; (3) the presence/absence of oxygenated states impacts the optical transition processes both from band-to-band and oxygenated states; and (4) the incremental addition/depletion of surface states in a tunable manner directly influences the carrier transport in the photoconductive device. Experiments show a two-stage transformation of RGO electronic properties with changing oxygen functionalities: oxidation (Stage I) and decomposition or erosion (Stage II). Sp <sup>2</sup> cluster size variation induced bandgap change was analyzed by Raman and photoluminescence studies, indicating the possibility for photodetection in a specific band encompassing NIR to UV, depending on the sp <sup>2</sup>/sp <sup>3</sup> ratio. Energy-dispersive x-ray spectroscopy and Fourier transform infrared studies confirm the surface oxygenation/de-oxygenation during plasma treatment, and XRD confirms partial transformation of RGO to GO and its amorphization at higher plasma exposure times. In addition, the photodetector performance is optimized in terms of carrier generation-recombination and carrier-lattice scattering. Thus, manipulating better photoconductive response is possible through suitable handling of the parameters involved in the plasma treatment process. This is the first study on the influence of the sp <sup>2</sup>/sp <sup>3</sup> ratio-induced lattice structure evolution on photodetection. Materials science ; Graphene ; Band gap ; Oxide ; Photodetection ; Surface modification ; Photoconductivity ; Raman spectroscopy ; Surface states ; Electronic band structure ; Photochemistry ; Optoelectronics ; Chemical engineering ; Nanotechnology ; Photodetector ; Optics ; Condensed matter physics ; Chemistry ; Surface (topology) Graphene research and applications ; Graphene and Nanomaterials Applications ; Ga2O3 and related materials
Authors: Huanrong Lan | Zhìqiáng Wú | Lihua Zhang | Ketao Jin | Shibing Wang
Source: Current Topics in Medicinal Chemistry (review, 2020-07-24)
Field: Materials Science — Biomaterials

Nanotechnology Assisted Chemotherapy for Targeted Cancer Treatment: Recent Advances and Clinical Perspectives Nanotechnology has recently provided exciting platforms in the field of anticancer research with promising potentials for improving drug delivery efficacy and treatment outcomes. Nanoparticles (NPs) possess different advantages over the micro and bulk therapeutic agents, including their capability to carry high payloads of drugs, with prolonged half-life, reduced toxicity of the drugs, and increased targeting efficiency. The wide variety of nanovectors, coupled with different conjugation and encapsulation methods available for different theranostic agents provide promising opportunities to fine-tune the pharmacological properties of these agents for more effective cancer treatment methods. This review discusses applications of NPs-assisted chemotherapy in preclinical and clinical settings and recent advances in design and synthesis of different nanocarriers for chemotherapeutic agents. Moreover, physicochemical properties of different nanocarriers, their impacts on different tumor targeting strategies and effective parameters for efficient targeted drug delivery are discussed. Finally, the current approved NPs-assisted chemotherapeutic agents for clinical applications and under different phases of clinical trials are discussed. Nanocarriers ; Drug delivery ; Nanotechnology ; Cancer treatment ; Cancer therapy ; Clinical trial ; Targeted drug delivery ; Drug ; Nanomedicine ; Medicine ; Pharmacology ; Cancer ; Materials science ; Nanoparticle ; Internal medicine Nanoparticle-Based Drug Delivery ; Graphene and Nanomaterials Applications ; Nanoplatforms for cancer theranostics
Authors: Shi‐Yuan Zhang | David Fairen‐Jiménez | Michael J. Zaworotko
Source: Angewandte Chemie (article, 2020-06-27)
Field: Chemistry — Inorganic Chemistry

Structural Elucidation of the Mechanism of Molecular Recognition in Chiral Crystalline Sponges Abstract To gain insight into chiral recognition in porous materials we have prepared a family of fourth generation chiral metal–organic frameworks (MOFs) that have rigid frameworks and adaptable (flexible) pores. The previously reported parent material, [Co 2 (S‐mandelate) 2 (4,4′‐bipyridine) 3 ](NO 3 ) 2 , CMOM‐ 1S , is a modular MOF; five new variants in which counterions (BF 4 − , CMOM‐ 2S ) or mandelate ligands are substituted (2‐Cl, CMOM‐ 11R ; 3‐Cl, CMOM‐ 21R ; 4‐Cl, CMOM‐ 31R ; 4‐CH 3 , CMOM‐ 41R ) and the existing CF 3 SO 3 − variant CMOM‐ 3S are studied herein. Fine‐tuning of pore size, shape, and chemistry afforded a series of distinct host–guest binding sites with variable chiral separation properties with respect to three structural isomers of phenylpropanol. Structural analysis of the resulting crystalline sponge phases revealed that host–guest interactions, guest–guest interactions, and pore adaptability collectively determine chiral discrimination. Molecular recognition ; Counterion ; Chemistry ; Sponge ; Bipyridine ; Stereochemistry ; Metal-organic framework ; Chirality (physics) ; Crystallography ; Materials science ; Molecule ; Ion ; Organic chemistry ; Crystal structure ; Chiral symmetry ; Adsorption Metal-Organic Frameworks: Synthesis and Applications ; Crystallography and molecular interactions ; Crystal structures of chemical compounds
Authors: Ayaat Mahmoud | Joshua P. Morrow | David Pizzi | Sepa Nanayakkara | Thomas P. Davis | Kei Saito | Kristian Kempe
Source: Macromolecules (article, 2020-01-06)
Field: Chemistry — Organic Chemistry

Nonionic Water-Soluble and Cytocompatible Poly(amide acrylate)s We report secondary amide side-chain-bearing polyacrylates with tunable aqueous solubility and cellular interaction. Redox-initiated reversible addition-fragmentation chain transfer polymerization of methylamide ethyl acrylate (MAmEA) and ethylamide ethyl acrylate (EAmEA) yielded well-defined homopolymers. P(MAmEA) and P(EAmEA) possess high glass-transition temperatures compared to the equivalent alkylated polyacrylates. P(EAmEA) showed a degree of polymerization and concentration-dependent lower critical solution temperature (LCST) behavior, which can be fine-tuned over a biologically relevant range through copolymerization of both monomers. No cytotoxicity against NIH 3T3 and RAW 264.7 cell lines was observed. Detailed cellular interaction studies revealed cell associations for P(MAmEA) similar to poly(N-acryloylmorpholine), a well-known nonionic water-soluble polymer and colocalization of both homopolymers with lysosomes. Due to the simple access of these monomers, the aqueous solubility, cytocompatibility, and cellular interaction of the homopolymers, and the possibility to combine them with a large number of acrylates, they hold great promise to become suitable building blocks for biomedical materials. Copolymer ; Polymer chemistry ; Lower critical solution temperature ; Monomer ; Chemistry ; Acrylate ; Polymerization ; Chain transfer ; Side chain ; Solubility ; Polymer ; Amide ; Aqueous solution ; Radical polymerization ; Organic chemistry Advanced Polymer Synthesis and Characterization ; Polymer composites and self-healing ; biodegradable polymer synthesis and properties
Authors: Joanna M. White | Justin Jurczyk | Ryan M. Van Horn
Source: Polymer Degradation and Stability (article, 2020-12-21)
Field: Materials Science — Biomaterials

Physical structure contributions in pH degradation of PEO-b-PCL films Crystallinity ; Chemical engineering ; Amorphous solid ; Materials science ; Crystallization ; Degradation (telecommunications) ; Ethylene oxide ; Oxide ; Polymer ; Copolymer ; Polycaprolactone ; Mass fraction ; Aqueous solution ; Polymer chemistry ; Organic chemistry ; Chemistry ; Composite material biodegradable polymer synthesis and properties ; Polymer crystallization and properties ; Advanced Polymer Synthesis and Characterization
Authors: Murilo Sodré Marques | Vinicius Hernandes | E. Lomba | José Rafael Bordin
Source: Journal of Molecular Liquids (article, 2020-10-05)
Field: Materials Science — Materials Chemistry

Competing interactions near the liquid-liquid phase transition of core-softened water/methanol mixtures Supercooling ; Anomaly (physics) ; Crystallization ; Thermodynamics ; Phase transition ; Chemical physics ; Maximum density ; Molecular dynamics ; Water model ; Critical point (mathematics) ; Core (optical fiber) ; Intermolecular force ; Phase (matter) ; Materials science ; Chemistry ; Condensed matter physics ; Physics ; Molecule ; Computational chemistry ; Organic chemistry Material Dynamics and Properties ; Phase Equilibria and Thermodynamics ; Theoretical and Computational Physics
Authors: Jagmeet Singh Sekhon
Source: Plasmonics (article, 2020-09-12)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Facile Tuning and Refractive Index Sensitivity of Localized Surface Plasmon Resonance Inflection Points in Hollow Silver Nanoshells Materials science ; Surface plasmon resonance ; Refractive index ; Nanoshell ; Inflection point ; Sensitivity (control systems) ; Optics ; Localized surface plasmon ; Plasmon ; Nanostructure ; Curvature ; Optoelectronics ; Nanotechnology ; Nanoparticle Gold and Silver Nanoparticles Synthesis and Applications ; Plasmonic and Surface Plasmon Research ; Advanced biosensing and bioanalysis techniques
Authors: Souad Hamzi | Ismail Mechab | Abbad Hichem | Noureddine Elmeiche
Source: Periodica Polytechnica Civil Engineering (article, 2020-11-05)
Field: Materials Science — Materials Chemistry

Vibration Analysis of Viscoelastic FGM Nanoscale Plate Resting on Viscoelastic Medium Using Higher-order Theory The present article aims essentially to present an analytical and numerical method which makes it possible to study the damped vibrations of viscoelastic FGM nanoplates resting on viscoelastic foundations. A new model for the higher-order shear deformation plate theory is coupled with the internal Kelvin - Voigt viscoelastic model and the three-parameter viscoelastic foundation model for the purpose of reducing and minimizing the vibration response of the system. It is widely admitted that the mechanical properties of these new functionally gradient materials (FGMs) vary according to the thickness of the plate and depend on its volume fraction. The use of FGM plates seems to be an ideal solution for the study of free vibrations because of their multifunctionality that is fully integrated with the nonlocal Eringen effect. The dynamic response of such a complex system has been investigated by varying the aspect ratio of the plate, the mechanical characteristics of the material used, the internal and external damping and the foundation rigidity. The results obtained, with and without the nonlocal effect, were compared with those of different models of higher-order theories and under various boundary conditions; they were found to be in good agreement with those reported in the literature. Viscoelasticity ; Vibration ; Materials science ; Rigidity (electromagnetism) ; Boundary value problem ; Mechanics ; Aspect ratio (aeronautics) ; Volume fraction ; Plate theory ; Material properties ; Composite material ; Physics ; Mathematical analysis ; Mathematics ; Acoustics Nonlocal and gradient elasticity in micro/nano structures ; Composite Structure Analysis and Optimization ; Numerical methods in engineering
Authors: Cesare Berton | Daniel Maria Busiello | Stefano Zamuner | Euro Solari | Rosario Scopelliti | Farzaneh Fadaei‐Tirani | Kay Severin | Cristian Pezzato
Source: ChemRxiv (preprint, 2020-05-31)
Field: Materials Science — Materials Chemistry

Thermodynamics and Kinetics of Protonated Merocyanine Photoacids in Water Metastable-state photoacids (mPAHs) are chemical species whose photo-activated state is long-lived enough to allow for proton diffusion. Liao’s photoacid (1) represents the archetype of mPAHs, and is being widely used on account of its unique capability to change the acidity of aqueous solutions reversibly. The behavior of 1 in water, however, still remains poorly understood. Herein, we provide in-dept insights on the thermodynamics and kinetics of 1 in water through a series of comparative 1H NMR and UV-Vis studies and relative modelling. Under dark conditions, we quantified a three-component equilibrium system where the dissociation (Ka) of the open protonated form (MCH) is followed by isomerization (Kc) of the open deprotonated form (MC) to the closed spiropyran form (SP) – i.e., in the absence of light, the ground state acidity can be expressed as KaGS = Ka(1+Kc). On the other hand, under powerful and continuous light irradiation we were able to assess, for the first time experimentally, the dissociation constant (KaMS) of the protonated metastable state (cis-MCH). In addition, we found that thermal ring-opening of SP is always rate-determining regardless of pH, whereas hydrolysis is reminiscent of what is found for Schiff bases. The proposed methodology is general, and it was applied to other two compounds bearing a shorter (ethyl, 2) and a longer (butyl, 3) alkyl-1-sulfonate bridge. We found that the pKa remains constant, whereas both pKc and pKaMS linearly increase with the length of the alkyl bridge. Importantly, all results are consistent with a four-component model cycle, which describes perfectly the full dynamics of proton release/uptake of 1‒3 in water. The superior hydrolytic stability and water solubility of compound 3, together with its relatively high pKaGS (low Kc), allowed us to achieve fully reversible jumps of 2.5 pH units over 18 consecutive cycles (6 hours). Chemistry ; Protonation ; Merocyanine ; Spiropyran ; Dissociation (chemistry) ; Deprotonation ; Metastability ; Kinetics ; Reaction rate constant ; Photochemistry ; Alkyl ; Isomerization ; Physical chemistry ; Organic chemistry ; Photochromism ; Ion ; Catalysis Photochromic and Fluorescence Chemistry ; Photochemistry and Electron Transfer Studies ; Light effects on plants
Authors: Aoibhín A. Cullen | Katharina Heintz | Laura O’Reilly | Conor Long | Andreas Heise | Robert D. Murphy | Joshua K. G. Karlsson | Elizabeth A. Gibson | Gregory M. Greetham | Michael Towrie | Mary T. Pryce
Source: Frontiers in Chemistry (article, 2020-10-19)
Field: Materials Science — Materials Chemistry

A Time-Resolved Spectroscopic Investigation of a Novel BODIPY Copolymer and Its Potential Use as a Photosensitiser for Hydrogen Evolution A novel 4,4-difuoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) copolymer with diethynylbenzene has been synthesised, and its ability to act as a photosensitiser for the photocatalytic generation of hydrogen was investigated by time-resolved spectroscopic techniques spanning the ps- to ns-timescales. Both transient absorption and time-resolved infrared spectroscopy were used to probe the excited state dynamics of this photosensitising unit in a variety of solvents. These studies indicated how environmental factors can influence the photophysics of the BODIPY polymer. A homogeneous photocatalytic hydrogen evolution system has been developed using the BODIPY copolymer and cobaloxime which provides hydrogen evolution rates of 319 μmol h<sup>-1</sup> g<sup>-1</sup> after 24 h of visible irradiation. BODIPY ; Photochemistry ; Copolymer ; Ultrafast laser spectroscopy ; Photocatalysis ; Spectroscopy ; Absorption spectroscopy ; Chemistry ; Excited state ; Time-resolved spectroscopy ; Materials science ; Fluorescence ; Polymer ; Catalysis ; Organic chemistry ; Optics ; Physics Luminescence and Fluorescent Materials ; Porphyrin and Phthalocyanine Chemistry ; Advanced Photocatalysis Techniques
Authors: Teseer Bahry | Zhenpeng Cui | Ariane Deniset‐Besseau | Matthieu Gervais | Israël M. Mbomekallé | Cyrille Sollogoub | Pierre‐Henri Aubert | Thanh‐Tuân Bui | Samy Rémita
Source: New Journal of Chemistry (article, 2020-01-01)
Field: Materials Science — Polymers and Plastics

Optimal strategy based on radiation chemistry for facile and direct synthesis of poly(3-thiophene acetic acid) polymers in water and dichloromethane γ-Induced polymerization was used as a novel method to easily synthesize nanostructured PTAA polymers in water and dichloromethane. Dichloromethane ; Acetic acid ; Polymer ; Polymerization ; Thiophene ; Chemistry ; Organic chemistry ; Polymer chemistry ; Solvent Conducting polymers and applications ; Organic Electronics and Photovoltaics ; Polymer Nanocomposite Synthesis and Irradiation
Authors: Soumya Mukherjee | Shoushun Chen | Andrey A. Bezrukov | Matthew Mostrom | Victor V. Terskikh | Douglas Franz | Shi‐Qiang Wang | Amrit Kumar | Man Chen | Brian Space | Yining Huang | Michael J. Zaworotko
Source: Angewandte Chemie (article, 2020-05-25)
Field: Chemistry — Inorganic Chemistry

Ultramicropore Engineering by Dehydration to Enable Molecular Sieving of H<sub>2</sub> by Calcium Trimesate Abstract The high energy footprint of commodity gas purification and increasing demand for gases require new approaches to gas separation. Kinetic separation of gas mixtures through molecular sieving can enable separation by molecular size or shape exclusion. Physisorbents must exhibit the right pore diameter to enable separation, but the 0.3–0.4 nm range relevant to small gas molecules is hard to control. Herein, dehydration of the ultramicroporous metal–organic framework Ca‐trimesate, Ca(HBTC)⋅H 2 O (H 3 BTC=trimesic acid), bnn‐1‐Ca‐H 2 O, affords a narrow pore variant, Ca(HBTC), bnn‐1‐Ca. Whereas bnn‐1‐Ca‐H 2 O (pore diameter 0.34 nm) exhibits ultra‐high CO 2 /N 2 , CO 2 /CH 4 , and C 2 H 2 /C 2 H 4 binary selectivity, bnn‐1‐Ca (pore diameter 0.31 nm) offers ideal selectivity for H 2 /CO 2 and H 2 /N 2 under cryogenic conditions. Ca‐trimesate, the first physisorbent to exhibit H 2 sieving under cryogenic conditions, could be a prototype for a general approach to exert precise control over pore diameter in physisorbents. Trimesic acid ; Selectivity ; Dehydration ; Chemistry ; Gas separation ; Molecule ; Metal-organic framework ; Analytical Chemistry (journal) ; Chemical engineering ; Crystallography ; Adsorption ; Physical chemistry ; Chromatography ; Catalysis ; Organic chemistry Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications
Authors: Ilhem Charfeddine | Jean‐Charles Majesté | Christian Carrot | Olivier Lhost
Source: Polymer (article, 2020-07-24)
Field: Materials Science — Polymers and Plastics

Predicting the Young's modulus and the impact strength of immiscible polyolefin blends Polyolefin ; Materials science ; Tacticity ; Polyethylene ; Izod impact strength test ; Polypropylene ; Rheology ; Composite material ; Modulus ; Phase (matter) ; High-density polyethylene ; Polymer blend ; Ziegler–Natta catalyst ; Polymerization ; Ultimate tensile strength ; Polymer ; Copolymer ; Organic chemistry ; Chemistry Polymer crystallization and properties ; biodegradable polymer synthesis and properties ; Polymer Nanocomposites and Properties
Authors: Henrik Hupatz | Marius Gaedke | Hendrik V. Schröder | Julia Beerhues | Arto Valkonen | Fabian Klautzsch | Sebastian Müller | Felix Witte | Kari Rissanen | Biprajit Sarkar | Christoph A. Schalley
Source: Beilstein Journal of Organic Chemistry (article, 2020-10-20)
Field: Chemistry — Spectroscopy

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes Crown ethers are common building blocks in supramolecular chemistry and are frequently applied as cation sensors or as subunits in synthetic molecular machines. Developing switchable and specifically designed crown ethers enables the implementation of function into molecular assemblies. Seven tailor-made redox-active crown ethers incorporating tetrathiafulvalene (TTF) or naphthalene diimide (NDI) as redox-switchable building blocks are described with regard to their potential to form redox-switchable rotaxanes. A combination of isothermal titration calorimetry and voltammetric techniques reveals correlations between the binding energies and redox-switching properties of the corresponding pseudorotaxanes with secondary ammonium ions. For two different weakly coordinating anions, a surprising relation between the enthalpic and entropic binding contributions of the pseudorotaxanes was discovered. These findings were applied to the synthesis of an NDI-[2]rotaxane, which retains similar spectroelectrochemical properties compared to the corresponding free macrocycle. The detailed understanding of the thermodynamic and electrochemical properties of the tailor-made crown ethers lays the foundation for the construction of new types of molecular redox switches with emergent properties. Chemistry ; Redox ; Supramolecular chemistry ; Rotaxane ; Electrochemistry ; Crown ether ; Isothermal titration calorimetry ; Tetrathiafulvalene ; Combinatorial chemistry ; Molecular switch ; Molecular tweezers ; Polymer chemistry ; Molecule ; Ion ; Organic chemistry ; Electrode ; Physical chemistry Molecular Sensors and Ion Detection ; Supramolecular Chemistry and Complexes ; Electrochemical Analysis and Applications
Authors: Lingxin Kong | Qing Wang | Weinan Yang | Jufang Shen | Yan Li | Xiaoqing Zheng | Lu Wang | Yiwen Chu | Zixin Deng | Yit‐Heng Chooi | Delin You
Source: ACS Chemical Biology (article, 2020-07-10)
Field: Chemistry — Organic Chemistry

Three Recently Diverging Duplicated Methyltransferases Exhibit Substrate-Dependent Regioselectivity Essential for Xantholipin Biosynthesis Polycyclic xanthones are characterized by highly oxygenated, angular hexacyclic frameworks and exhibit diverse biological activities. Although many of them have been isolated and chemically synthesized, the detailed biosynthetic machinery awaits discovery. Recently, xanthone construction in the xantholipin (<b>1</b>) pathway was shown to involve cryptic demethoxylation. This suggested a rationale for the existence of three <i>O</i>-methyltransferase (OMT) genes in the gene cluster, although there are only two <i>O</i>-methyl groups in the structure of <b>1</b>. Here, <i>in vivo</i> and <i>in vitro</i> analysis have been used to show that the three paralogous OMTs, XanM1-M3, introduce individual methyl groups at specific points in the biosynthetic pathway. Each OMT can to some extent take over the role of the other OMTs, although they exhibit highly substrate-dependent regiospecificity. In addition, phylogenetic analysis suggests their evolution from a common ancestor. Four putative ancestral proteins were constructed, and one of them performed all the functions of XanM1-M3, while the others possessed more limited catalytic functions. The results suggest that a promiscuous common ancestor may have been able to catalyze all three reactions prior to gene duplication and functional divergence. The characterization of XanM1-M3 expands the enzyme inventory for polycyclic xanthone biosynthesis and suggests novel directed evolution approaches to diversifying natural product pathways. Methyltransferase ; Xanthone ; Gene ; Gene duplication ; Biology ; Biosynthesis ; Gene cluster ; Phylogenetic tree ; Genetics ; Computational biology ; Methylation ; Botany Carbohydrate Chemistry and Synthesis ; Plant Gene Expression Analysis ; Plant biochemistry and biosynthesis