jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Xiaosong Wang | Tong Zhao | Yihan Wang | Li Zhang | Liang Zou
Source: Polymers (article, 2022-03-15)
Field: Materials Science — Materials Chemistry

Microscopic Pyrolytic and Electric Decomposition Mechanism of Insulating Polyimide/Boron Nitride Nanosheet Composites based on ReaxFF High thermal conductivity insulating materials with excellent comprehensive properties can be obtained by doping boron nitride nanosheets (BNNSs) into polyimide (PI). To study the microscopic mechanism of composite material decomposition in an actual working environment and the inhibitory effect of BNNS doping on the decomposition process, molecular dynamics simulations were carried out at high temperatures, in intense electric fields, and with various reactive species in plasma based on the reactive force field (ReaxFF). The results showed that the decomposition was mainly caused by hydrogen capture and adsorption, which broke the benzene ring and C-N bond on the PI chains and led to serious damage to the PI structure. The BNNS filling was shown to inhibit the decomposition of the PI matrix at high temperatures and in intense electric fields. Moreover, the BNNS filling also inhibited the material decomposition caused by ·OH and ·NO. The erosive effect of the positive corona on the PI composites was more obvious than that of the negative corona. In this paper, the microscopic dynamic reaction paths of material pyrolysis in various environments were revealed at the atomic level, and it was concluded that BNNS doping could effectively inhibit the decomposition of PI in various environments. ReaxFF ; Materials science ; Boron nitride ; Nanosheet ; Polyimide ; Composite material ; Thermal decomposition ; Electric field ; Pyrolysis ; Decomposition ; Chemical engineering ; Hydrogen bond ; Nanotechnology ; Chemistry ; Organic chemistry ; Molecule High voltage insulation and dielectric phenomena ; Thermal properties of materials ; Dielectric materials and actuators
Authors: Jie Zheng | Ling Wang | Shengyao Wang | Jing-fang Chen | Xing Wang | Haining Duan | Yile Liang | Xuetao Ding
Source: Complex & Intelligent Systems (article, 2022-04-29)
Field: Chemistry — Analytical Chemistry

Modeling stochastic service time for complex on-demand food delivery Abstract Uncertainty is everywhere in the food delivery process, which significantly influences decision-making for complex on-demand food delivery problems, affecting delivery efficiency and customer satisfaction. Especially, the service time is an indispensable part of the delivery process impacted by various uncertain factors. Due to the simplicity and high accuracy requirement, we model the uncertain service time as a Gaussian mixture model (GMM). In detail, we transform the distribution estimation problem into a clustering problem by determining the probability of each data belonging to each component (each cluster as well). A hybrid estimation of distribution algorithm is proposed to intelligently solve the clustering problem with the criterion to optimize quality and simplicity simultaneously. First, to optimize the simplicity, problem-specific encoding and decoding methods are designed. Second, to generate initial solutions with good clustering results, a Chinese restaurant process-based initialization mechanism is presented. Third, a weighted-learning mechanism is proposed to effectively guide the update of the probability model. Fourth, a local intensification based on maximum likelihood is used to exploit better solutions. The effect of critical parameters on the performances of the proposed algorithm is investigated by the Taguchi design of the experimental method. To demonstrate the effectiveness of the proposed algorithm, we carry out extensive offline experiments on real-world historical data. Besides, we employ the GMMs obtained by our algorithm in a real-world on-demand food delivery platform, Meituan, to assist decision-making for order dispatching. The results of rigorous online A/B tests verify the practical value of introducing the uncertainty model into the real-life application. Cluster analysis ; Computer science ; Initialization ; Mixture model ; Process (computing) ; Data mining ; Service (business) ; Mathematical optimization ; Machine learning ; Artificial intelligence ; Mathematics Spectroscopy and Chemometric Analyses ; Sensory Analysis and Statistical Methods ; Bayesian Methods and Mixture Models
Authors: Pavel Michal | Jana Hudecová | Radek Čelechovský | Milan Vůjtek | Michal Dudka | Josef Kapitán
Source: Symmetry (article, 2022-05-12)
Field: Chemistry — Spectroscopy

Accurate Determination of Enantiomeric Excess Using Raman Optical Activity The optical purity of a chiral sample is of particular importance to the analytical chemistry and pharmaceutical industries. In recent years, the vibrational optical activity (VOA) has become established as a sensitive and nondestructive technique for the analysis of chiral molecules in solution. However, the relatively limited accuracy in the range of about 1–2% reported in published papers and the relatively small spread of experimental facilities to date have meant that vibrational spectroscopy has not been considered a common method for determining enantiomeric excess. In this paper, we attempt to describe, in detail, a methodology for the determination of enantiomeric excess using Raman optical activity (ROA). This method achieved an accuracy of 0.05% for neat α-pinene and 0.22% for alanine aqueous solution, after less than 6 h of signal accumulation for each enantiomeric mixture, which we believe is the best result achieved to date using vibrational optical activity techniques. An algorithm for the elimination of systematic errors (polarization artifacts) is proposed, and the importance of normalizing ROA spectra to correct for fluctuations in excitation power is established. Results comparable to those obtained with routinely used chemometric analysis by the partial least squares (PLS) method were obtained. These findings show the great potential of ROA spectroscopy for the quantitative analysis of enantiomeric mixtures. Raman optical activity ; Enantiomeric excess ; Raman spectroscopy ; Enantiomer ; Chemistry ; Analytical Chemistry (journal) ; Spectroscopy ; Polarization (electrochemistry) ; Aqueous solution ; Molecule ; Optics ; Physical chemistry ; Chromatography ; Organic chemistry ; Physics ; Enantioselective synthesis Molecular spectroscopy and chirality ; Metabolomics and Mass Spectrometry Studies ; Analytical Chemistry and Chromatography
Authors: Kristaps Saršu̅ns | Meldra Ķemere | Aleksejs Karziņins | Igors Kļimenkovs | Agris Be̅rziņš | Anatolijs Šarakovskis | Toms Rekis
Source: Crystal Growth & Design (article, 2022-07-08)
Field: Materials Science — Materials Chemistry

Fine-Tuning Solid State Luminescence Properties of Organic Crystals via Solid Solution Formation: The Example of 4-Iodothioxanthone–4-Chlorothioxanthone System Solid solutions with fine-tunable photoluminescence have been obtained in a 4-iodothioxanthone–4-chlorothioxanthone system. Both pure components are room-temperature luminophors demonstrating different luminescence properties. It was discovered that in the 4-chlorothioxanthone structure, up to half of the molecules can be replaced by the iodo analogue obtaining solid solutions in the respective composition range. Despite this solid solution existing in such a large composition range, the variation of the luminescence spectra is not substantial. In the 4-iodothioxanthone structure, only up to ∼20% of the molecules can be replaced by the chloro analogue before the composition limit of this solid solution is reached. In contrast, there is a strong composition-dependent response of the luminescence. A considerable change in luminescence spectra is observed even if only a few mol % of the opposite component is added. The spectra of mechanical mixtures of pure components are different from those of the solid solutions, which demonstrates the unique behavior of the newly obtained solid phases. This study shows great potential to use solid solution engineering in the organic solid state to tune material properties in a continuum as opposed to other crystal engineering approaches, leading to property tunability in a stepwise fashion. Luminescence ; Solid solution ; Solid-state ; Molecule ; Photoluminescence ; Materials science ; Crystal (programming language) ; Spectral line ; Crystal structure ; Chemical physics ; Chemistry ; Physical chemistry ; Crystallography ; Organic chemistry ; Optoelectronics Luminescence and Fluorescent Materials ; Polydiacetylene-based materials and applications ; Perovskite Materials and Applications
Authors: Jinguo Wu | Xuezhao Li | Pengyan Wu | Zhuolin Shi | Liyong Chen | Rong Zhang | Cheng He | Chunying Duan
Source: Chemistry of Materials (article, 2022-05-11)
Field: Chemistry — Inorganic Chemistry

Engineering Homochiral Dinuclear Ir(III)-Metallohelix-Based Porous Molecular Crystals for Atropisomer Enantioseparation Porous molecular crystal materials offer promising applications for enantioselective separation and asymmetric catalysis, while regulating the chiral channel environment remains challenging yet. Herein, we report the introduction of homochiral dinuclear Ir(III) triple-stranded helicates as molecular blocks to fabricate chiral porous crystals for the effective enantioseparation of atropisomers. The chiral cyclohexylamine-functionalized robust helicates Δ2R6-H and Λ2S6-H exhibit remarkable stereochemical stability (>6 months) and present superb enantioseparation abilities toward atropisomers, yielding >99% ee for BINOL in only one adsorption and separation cycle. Importantly, these molecular crystals can provide consistent ee values (>99%) even after 10 cycles of enantioseparation. With simple regulation of the helicands with achiral ethylenediamine, the resulting helicates Δ2-H and Λ2-H display similar adsorption ability toward BINOL but no enantioselectivity. This study highlights that introducing and fine-tuning the configuration of homochiral helicates to fabricate porous molecular crystals is anticipated for enantioselective separation. Atropisomer ; Enantioselective synthesis ; Chirality (physics) ; Ethylenediamine ; Chemistry ; Adsorption ; Molecule ; Combinatorial chemistry ; Materials science ; Crystallography ; Catalysis ; Organic chemistry Metal-Organic Frameworks: Synthesis and Applications ; Supramolecular Chemistry and Complexes ; Axial and Atropisomeric Chirality Synthesis
Authors: Wengang Zhang | Yuanchi Ma | Nicholas D. Posey | Michael Lueckheide | Vivek M. Prabhu | Jack F. Douglas
Source: Macromolecules (article, 2022-07-14)
Field: Chemistry — Physical and Theoretical Chemistry

Combined Simulation and Experimental Study of Polyampholyte Solution Properties: Effects of Charge Ratio, Hydrophobic Groups, and Polymer Concentration Polyampholytes are polymers with both cationic and anionic monomers that have many features in common with proteins. These molecules have many applications associated with their natural biocompatibility and their propensity to form viscoelastic fluids and gels due to their common tendency to form self-assembled structures in solution. Recently, advances in the synthesis capabilities have enabled the fine-tuning of the monomer structure and composition, such as the sequence and ratio of the charged and hydrophobic groups. We correspondingly investigate these molecular characteristics on the solution properties of a series of poly(carbonate)-based polyampholytes using both molecular dynamics simulations and small-angle neutron scattering measurements. Our simulations suggest the importance of hydrophobic groups for understanding the observed properties of our polyampholyte solutions, a well-known fact for protein solutions. In particular, our simulations indicate that the hydrophobic groups cause the polyampholyte chains to form compact micelle-like rather than diffuse clusters at low concentrations and greatly influence the concentration dependence of the correlation peak in the structure factor describing the correlation distance between the polyampholyte chains in solution. We also construct a polyampholyte solution association map where the polymer concentration and charge ratios lead to different propensities of association (or clustering) and determine a self-assembly boundary governing the transition between self-assembled clusters that resemble micelles and a transient polymer network that percolates the system. Micelle ; Polymer ; Monomer ; Chemistry ; Chemical physics ; Cationic polymerization ; Molecular dynamics ; Copolymer ; Hydrophobic effect ; Self-assembly ; Chemical engineering ; Polymer chemistry ; Aqueous solution ; Computational chemistry ; Physical chemistry ; Organic chemistry Electrostatics and Colloid Interactions ; Surfactants and Colloidal Systems ; Material Dynamics and Properties
Authors: Cristian Peptu | Alexandra-Diana Diaconu | Maricel Danu | Cătălina A. Peptu | Mariana Cristea | Valeria Harabagiu
Source: Gels (article, 2022-06-02)
Field: Materials Science — Polymers and Plastics

The Influence of the Hydroxyl Type on Crosslinking Process in Cyclodextrin Based Polyurethane Networks The influence of the hydroxyl groups (OH) type on the polyaddition processes of isocyanates represents a critical approach for the design of multicomponent polyurethane systems. Herein, to prove the effect of hydroxyl nature on both the isocyanate-OH polyaddition reactions and the structure/properties of the resulting networks, two structurally different cyclodextrins in terms of the primary and secondary groups' ratio were analyzed, namely native β-cyclodextrin (CD) and its derivative esterified to the primary hydroxyl groups with oligolactide chains (CDLA). Thus, polyurethane hydrogels were prepared via the polyaddition of CD or CDLA to isophorone diisocyanate polyethylene glycol-based prepolymers (PEG-(NCO)<sub>2</sub>). The degradable character of the materials was induced by intercalating oligolactide short sequences into the polymer chains composing the polymer network. In order to establish the influence of the OH type, the synthesis of polyurethane hydrogels was analyzed by a rheological investigation of the overall system reactivity. Materials properties such as swelling behavior, thermal properties and hydrolytic degradation were influenced by the reaction feed. Specifically, the presence of primary OH groups leads to more compact networks with similar water uptake, disregarding the CD content, while the predominance of secondary OH groups together with the presence of oligolactide spacers leads to the fine tuning of the water swelling properties. Isophorone diisocyanate ; Polyurethane ; Isocyanate ; Polymer chemistry ; Ethylene glycol ; Swelling ; Polyethylene glycol ; Cyclodextrin ; Self-healing hydrogels ; PEG ratio ; Prepolymer ; Polymer ; Chemistry ; Hexamethylene diisocyanate ; Reactivity (psychology) ; Materials science ; Organic chemistry Polymer composites and self-healing ; Hydrogels: synthesis, properties, applications ; Advanced Polymer Synthesis and Characterization
Authors: Liman Hou | Hongxue Xu | Xuanyu Zhang | Yipeng Zhang | Rui Chen | Zhaoyu Zhang | Mingfeng Wang
Source: Macromolecules (article, 2022-09-30)
Field: Materials Science — Materials Chemistry

Impact of Polymer Rigidity on the Thermoresponsive Luminescence and Electron Spin Resonance of Polyester-Tethered Single Radicals Stable organic radicals represent a unique type of functional materials for a broad scope of applications in optoelectronic and spintronic devices. A central challenge toward these applications is how to suppress the inter-radical aggregation that often causes aggregation-induced photoluminescence quenching and limits the correlation lifetime of the electron spins from the radicals. Here, we report an effective approach to fine-tuning luminescence and spin dynamics using a series of polyester-tethered single radicals, with a common core of carbazole-triphenylmethyl radical but different chains of polyesters with distinct glass transition temperature and rigidity. The rigidity of the polymeric matrices plays a critical role in tuning the luminescence and electron spin resonance of the radicals. The tunable properties of luminescence and electron spin dynamics as well as the robust photostability of such polymer-tethered single radicals represent important attributes for cutting-edge applications in optoelectronic devices and quantum information technologies. Electron paramagnetic resonance ; Radical ; Luminescence ; Polyester ; Rigidity (electromagnetism) ; Polymer ; Materials science ; Photochemistry ; Polymer chemistry ; Chemistry ; Nuclear magnetic resonance ; Composite material ; Optoelectronics ; Organic chemistry ; Physics Luminescence and Fluorescent Materials ; Organic Light-Emitting Diodes Research ; Photochemistry and Electron Transfer Studies
Authors: Kerstin Wissel | Fabio Bernardini | Heesu Oh | Sami Vasala | Roland Schoch | Björn Blaschkowski | Pieter Glatzel | Matthias Bauer | Oliver Clemens | A. Cano
Source: Chemistry of Materials (article, 2022-08-02)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Single-Layer T′ Nickelates: Synthesis of the La and Pr Members and Electronic Properties across the Rare-Earth Series Understanding high-temperature unconventional superconductivity has become a long-lasting problem in which the cuprates stand as central reference materials. Given this impasse, the recent discovery of superconductivity in analogous nickelate thin films represents a fundamental breakthrough calling for the identification of additional materials in this class. In particular, thermodynamically more robust systems are required to “upgrade” nickelate superconductors from thin films to bulk samples. Here, we contribute in this direction by reporting the synthesis of the new single-layer T′ Pr2NiO3F compound, assessing this synthesis in relation to the only previous T′ nickelate La2NiO3F, and analyzing the electronic properties across the R2NiO3F series (R = La–Lu) via first-principles calculations. We find that these mixed anion systems have a comparatively high degree of stability and their synthesis enables a fine-tuning of their composition as inferred from their characterization. Furthermore, we find that these unprecedented square-planar nickelates hold great promise as prospective superconductors due to their exceptional electronic structure. Series (stratigraphy) ; Rare earth ; Layer (electronics) ; Materials science ; Earth (classical element) ; Electronic structure ; Crystallography ; Engineering physics ; Nanotechnology ; Mineralogy ; Physics ; Condensed matter physics ; Chemistry ; Geology Magnetic and transport properties of perovskites and related materials ; Iron-based superconductors research ; Inorganic Chemistry and Materials
Authors: Sabina Quader | Joachim F. R. Van Guyse
Source: Polymers (review, 2022-09-03)
Field: Materials Science — Biomaterials

Bioresponsive Polymers for Nanomedicine—Expectations and Reality! Bioresponsive polymers in nanomedicine have been widely perceived to selectively activate the therapeutic function of nanomedicine at diseased or pathological sites, while sparing their healthy counterparts. This idea can be described as an advanced version of Paul Ehrlich's magic bullet concept. From that perspective, the inherent anomalies or malfunction of the pathological sites are generally targeted to allow the selective activation or sensory function of nanomedicine. Nonetheless, while the primary goals and expectations in developing bioresponsive polymers are to elicit exclusive selectivity of therapeutic action at diseased sites, this remains difficult to achieve in practice. Numerous research efforts have been undertaken, and are ongoing, to tackle this fine-tuning. This review provides a brief introduction to key stimuli with biological relevance commonly featured in the design of bioresponsive polymers, which serves as a platform for critical discussion, and identifies the gap between expectations and current reality. Nanomedicine ; Polymer ; Nanotechnology ; Materials science ; Polymer science ; Nanoparticle ; Composite material Nanoparticle-Based Drug Delivery ; Graphene and Nanomaterials Applications ; Electrospun Nanofibers in Biomedical Applications
Authors: Shi Yan Liew | Aishah Abdul Jalil | Jinchi Tan
Source: Journal of Physics Conference Series (review, 2022-04-01)
Field: Materials Science — Materials Chemistry

A short review on the promotional effects of ceria-based catalyst for dry reforming methane Abstract Dry reforming of methane (DRM) appears as a promising process for the industrial production of syngas in comparison to other conventional reforming technologies. However, DRM process suffers from catalyst deactivation induced by carbonaceous species which reduces the catalyst lifespan. Currently, catalytic designs in DRM have trended towards the incorporation rare-earth metals. As such, ceria (Ce) based catalyst has recently attracted research interest for its key feature to mitigate catalyst deactivation owing to its complementary redox and oxygen storage properties for the removal of surface carbon deposit. The present short review summarizes on the recent catalytic performance of Ce-based catalyst and impact of ceria redox on the DRM mechanism. The utilization of oxygen vacancies introduced by the Ce redox support enhances the catalytic activity by providing additional bifunctional sites and intermediate species to facilitate the surface reaction rate. This perspective will elucidate the role of oxygen vacancies in Ce supports and fine tune the catalytic performance of DRM for industrial applications. Catalysis ; Syngas ; Bifunctional ; Redox ; Oxygen storage ; Carbon dioxide reforming ; Methane ; Chemical engineering ; Materials science ; Oxygen ; Nanotechnology ; Chemistry ; Inorganic chemistry ; Organic chemistry Catalytic Processes in Materials Science ; Catalysts for Methane Reforming ; Catalysis and Oxidation Reactions
Authors: Luca Vaghi | Fabio Rizzo | Jacopo Pedrini | Anna Mauri | Francesco Meinardi | Ugo Cosentino | Claudio Greco | Angelo Monguzzi | Antonio Papagni
Source: Photochemical & Photobiological Sciences (article, 2022-04-30)
Field: Materials Science — Materials Chemistry

Bypassing the statistical limit of singlet generation in sensitized upconversion using fluorinated conjugated systems The photon upconversion based on triplet-triplet annihilation (TTA) is a mechanism that converts the absorbed low-energy electromagnetic radiation into higher energy photons also at extremely low excitation intensities, but its use in actual technologies is still hindered by the limited availability of efficient annihilator moieties. We present here the results obtained by the synthesis and application of two new fluorinated chromophores based on phenazine and acridine structures, respectively. Both compounds show upconverted emission demonstrating their ability as TTA annihilator. More interesting, the acridine-based chromophore shows an excellent TTA yield that overcomes the one of some of best model systems. By correlating the experimental data and the quantum mechanical modeling of the investigated compound, we propose an alternative efficient pathway for the generation of the upconverted emissive states involving the peculiar high-energy triplet levels of the dye, thus suggesting a new development strategy for TTA annihilators based on the fine tuning of their high-energy excited states properties. Photon upconversion ; Chromophore ; Acridine ; Excited state ; Quantum yield ; Photochemistry ; Singlet state ; Chemistry ; Conjugated system ; Materials science ; Optoelectronics ; Doping ; Fluorescence ; Atomic physics ; Physics ; Optics ; Organic chemistry Luminescence and Fluorescent Materials ; Luminescence Properties of Advanced Materials ; Organic Light-Emitting Diodes Research