bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Inner Topological Pressure within the Topological Insulators
Authors: Faílde Daniel , Baldomir Daniel 
Published: November 2021

AbstractTopological insulators (TIs) have axion electrodynamics instead of the usual Maxwell. Then, there is an additional energy density, whose origin is topological, generating a pressure that is found analytically. It is shown that the topological electric and magnetic fields act only on the surface, while the scalar axion does as a real Klein–Gordon field in all the TI, giving rise to a behavior quite similar to the Casimir effect without the intervention of the virtual photons of the vacuum. This opens the possibility to experimentally test the electrodynamics of axions for the TIs.
Direct Evidence of Subsurface Oxygen Formation in Oxide‐Derived Cu by X‐ray Photoelectron Spectroscopy
Authors: Wang Hsin‐Yi , Soldemo Markus , Degerman David , Lömker Patrick , Schlueter Christoph , Nilsson Anders , Amann Peter 
Published: November 2021

AbstractSubsurface oxygen has been proposed to be crucial in oxide‐derived copper (OD‐Cu) electrocatalysts for enhancing the binding of CO intermediates during CO2 reduction reaction (CO2RR). However, the presence of such oxygen species under reductive conditions still remains debated. In this work, the existence of subsurface oxygen is validated by grazing incident hard X‐ray photoelectron spectroscopy, where OD‐Cu was prepared by reduction of Cu oxide with H2 without exposing to air. The results suggest two types of subsurface oxygen embedded between the fully reduced metallic surface and the Cu2O buried beneath: (i) oxygen staying at lattice defects and/or vacancies in the surface‐most region and (ii) interstitial oxygen intercalated in metal structure. This study adds convincing support to the presence of subsurface oxygen in OD‐Cu, which previously has been suggested to play an important role to mitigate the σ‐repulsion of Cu for CO intermediates in CO2RR.
Accelerated SuFEx Click Chemistry For Modular Synthesis**
Authors: Smedley Christopher J. , Homer Joshua A. , Gialelis Timothy L. , Barrow Andrew S. , Koelln Rebecca A. , Moses John E. 
Published: November 2021

AbstractSuFEx click chemistry is a powerful method designed for the selective, rapid, and modular synthesis of functional molecules. Classical SuFEx reactions form stable S−O linkages upon exchange of S−F bonds with aryl silyl‐ether substrates, and while near‐perfect in their outcome, are sometimes disadvantaged by relatively high catalyst loadings and prolonged reaction times. We herein report the development of accelerated SuFEx click chemistry (ASCC), an improved SuFEx method for the efficient and catalytic coupling of aryl and alkyl alcohols with a range of SuFExable hubs. We demonstrate Barton's hindered guanidine base (2‐tert‐butyl‐1,1,3,3‐tetramethylguanidine; BTMG) as a superb SuFEx catalyst that, when used in synergy with silicon additive hexamethyldisilazane (HMDS), yields stable S−O bond linkages in a single step; often within minutes. The powerful combination of BTMG and HMDS reagents allows for catalyst loadings as low as 1.0 mol % and, in congruence with click‐principles, provides a scalable method that is safe, efficient, and practical for modular synthesis. ASSC expands the number of accessible SuFEx products and will find significant application in organic synthesis, medicinal chemistry, chemical biology, and materials science.
syn/anti‐Oligothienoacene Diimides with up to 10 Fused Rings
Authors: Wen Jingjing , Qiu Fei , Liu Han , Liu Xinyue , Hu Hui , Duan Yuxiao , Wang Zhaohui , Zhang Lei 
Published: November 2021

AbstractWe report a facile and powerful strategy to prepare libraries of oligothienoacene diimides that include anti‐ and syn‐isomers using palladium‐catalyzed C−H activation and an unexpected 1,2‐sulfur migration. Through this strategy, a series of oligothienoacene diimides containing 6, 8, and 10 fused rings were synthesized. The molecular geometry and extent of π‐conjugation have dramatic effects on the electronic properties, degree of crystallinity, and charge‐carrier transport properties. Notably, single‐crystal microfibers of syn‐3 c show electron mobilities up to 4.2 cm2 V−1 s−1, illustrating the significant potential of these materials for organic electronic devices. Our work demonstrates the versatility of this strategy for the development of oligothienoacene diimide libraries, in particular complex and large syn‐oligothienoacene diimides, which are difficult to prepare by present methods.
What Distinguishes the Strength and the Effect of a Lewis Acid: Analysis of the Gutmann–Beckett Method
Authors: Erdmann Philipp , Greb Lutz 
Published: November 2021

AbstractIUPAC defines Lewis acidity as the thermodynamic tendency for Lewis pair formation. This strength property was recently specified as global Lewis acidity (gLA), and is gauged for example by the fluoride ion affinity. Experimentally, Lewis acidity is usually evaluated by the effect on a bound molecule, such as the induced 31P NMR shift of triethylphosphine oxide in the Gutmann–Beckett (GB) method. This type of scaling was called effective Lewis acidity (eLA). Unfortunately, gLA and eLA often correlate poorly, but a reason for this is unknown. Hence, the strength and the effect of a Lewis acid are two distinct properties, but they are often granted interchangeably. The present work analyzes thermodynamic, NMR specific, and London dispersion effects on GB numbers for 130 Lewis acids by theory and experiment. The deformation energy of a Lewis acid is identified as the prime cause for the critical deviation between gLA and eLA but its correction allows a unification for the first time.
Hygrothermal aging and water absorption behavior of radial tire composites
Authors: Jiang Ning , Li Mengdi , Li Di , Li Yuankun , Zhang Ru , Song Hui , Liu Xingfeng , Ge Wenqing , Li Ning , Chen Chaozhong 
Published: November 2021

AbstractRadial tires (RT) are widely used in the automobile. However, the moisture absorption characteristics of the tire in the hygrothermal environment accelerate tire aging and affect the service life. This work focused on the water absorption behavior and durability of RT composites in the hygrothermal environment. The effects of aging in water at 30, 60, and 90°C on water absorption, chemical degradation, and internal structure of RT composites were investigated. The results showed that the water diffusion of RT composites followed the Fickian's law of diffusion in the initial stage. The kinetic parameters of water absorption were also determined at this stage and were closely related to the change of temperature. Then, moisture led to the poor interface and the degradation of RT composites. Natural rubber (NR) matrix swelled due to the invasion of water, which developed stresses that could cause microcracks of the matrix in the second stage. Moreover, moisture promoted hydrolysis of the NR matrix and agents in the third stage. The water molecules existed in unbound water and bound water, which made the water diffusion followed the Langmuir adsorption model.
Barrier behavior evaluation of polyamide 12 nanoclay composite to offshore application by electrochemical impedance spectroscopy
Authors: Valério Murilo B. , dos Santos Larissa E. G. , de Carvalho Ladimir J. , Reznik Leila Y. , da Silva Ana Lúcia Nazareth 
Published: November 2021

AbstractCommercially, polyamide 12 (PA12) is one of the polymers applied as an internal insulation layer in offshore exploitation. The present study aims to produce a hybrid system based on PA12 with 5 wt% of a nanoclay grade (montmorillonite – MMT) and evaluate its effect on the barrier behavior of the PA12 matrix, the exact grade used in the pressure layer of flexible pipe, over carbon steel AISI 1020, metallic alloy responsible for providing the mechanical properties to flexible pipes. The barrier behavior, related to ion and molecule diffusion in synthetic production water, was assessed by Electrochemical Impedance Spectroscopy (EIS) and linear sweep voltammetry (LSV) analysis, which allow for interpreting the carbon steel corrosion mechanisms. One also carried out Fourier transform infrared, X‐ray diffraction, and Scanning electron microscopy analyzes. The data showed that the MMT lamellae are well‐dispersed in the PA12 matrix. EIS and LSV analysis results showed higher corrosion protection efficiency by the system composed of PA12/MMT once compared to the system without adding the load.
Structural and functional properties of collagen from tilapia scales pretreated by heat‐assisted ionic liquids
Authors: Huang Liurong , Ding Shuang , Chen Tian , Wu Ruike , Wang Xinyu , Jia Shifang 
Published: November 2021

AbstractThis paper explores the structural and functional properties of collagen from tilapia scales pretreated by heat‐assisted ionic liquids (ILs). Results show that the solubility of collagen was significantly influenced by the type and concentration of ILs. With the increase of IL concentration, a remarkable decrease in solubility of collagen was seen. Fluorescence spectra show that heat and IL pretreatments induced the exposure of chromophores. Changes in sodium dodecyl sulfate–polyacrylamide gel electrophoresis indicated that subunits of collagen regenerated from most of the IL solvent systems were not destroyed. The functional properties of regenerated collagen were evaluated by gel strength, viscosity, water‐binding capacity, and emulsifying capacity. Results show that all heat‐assisted ILs pretreatments improved the gel strength and viscosity, and the highest gel strength and viscosity were both obtained in the collagen pretreated by heat‐assisted [EMIM]Cl. Heat‐assisted [BMIM]BF4 pretreatment exhibited the lowest water‐binding capacity. Heat‐assisted [BDMIM]Cl pretreatment indicated superior effect on improving emulsifying capacity than other pretreatments due to its ability to break most of the hydrogen bonds in collagen molecules, resulting in the formation of new re‐aggregates with higher solubility and more hydrophobic groups.
E2F transcription factor 1 elevates cyclin D1 expression by suppressing transcription of microRNA‐107 to augment progression of glioma
Authors: Xie Huan , Lv Shigang , Wang Zhaozhen , Yuan Xinzhang 
Published: November 2021

AbstractBackgroundDysregulation of microRNAs has been frequently implicated in the progression of human diseases, including glioma. This study aims to explore the interaction between E2F transcription factor 1 (E2F1) and miR‐107 in the progression of glioma.MethodsExpression of miR‐107 in glioma tissues and cells was examined. Putative binding sites between E2F1 and the promoter region of miR‐107, and between miR‐107 and cyclin D1 (CCND1) mRNA were predicted via bioinformatic systems and validated via chromatin immunoprecipitation and luciferase reporter gene assays. Altered expression of miR‐107, E2F1, and CCND1 was introduced in A172 and T98G cells to examine their roles in cell growth and the activity of the Wnt/β‐catenin signaling. In vivo experiments were performed by injecting cells in nude mice.ResultsmiR‐107 was poorly expressed, whereas E2F1 and CCND1 were highly expressed in glioma tissues and cells. E2F1 bound to the promoter region of miR‐107 to induce transcriptional repression, and miR‐107 directly bound to CCND1 mRNA to reduce its expression. Overexpression of miR‐107 reduced proliferation, migration and invasion, and augmented apoptosis of glioma cells, and it reduced activity of the Wnt/β‐catenin pathway. The anti‐tumorigenic roles of miR‐107 were blocked by E2F1 or CCND1 overexpression. Similar results were reproduced in vivo where miR‐107 overexpression or E2F1 inhibition blocked tumor growth in nude mice.ConclusionThis study suggested that E2F1 reduces miR‐107 transcription to induce CCND1 upregulation, which leads to progression of glioma via Wnt/β‐catenin signaling activation.
Modeling of Catalytic CO2 Methanation Using Smart Computational Schemes
Authors: Dashti Amir , Bazdar Mahsa , Akbari Fakhrabadi Ehsan , Mohammadi Amir H. 
Published: November 2021

AbstractAn analyzing tool as a sustainable method to combine CO2 capture and production of CH4 by utilizing CO2 as a feedstock is proposed. The impact of incorporating metallic promoters such as Fe, La, Ce, and Co to an Al2O3‐supported catalyst containing Ni as the first metal in the CO2 methanation was modeled. Smart models were employed to analyze the CO2 conversion and CH4 selectivity in CH4 production from CO2. The genetic programming (GP) model provides a mathematical framework for the estimation of CO2 conversion and CH4 selectivity. The model inputs are catalyst surface area, temperature, H2/CO2 ratio, gas‐hourly space velocity, and catalyst pore volume and diameter. The results confirm that the GP model estimates the CO2 conversion and CH4 selectivity very well.
Herbage accumulation and nutritive value of stockpiled limpograss and ‘Tifton 85' bermudagrass
Authors: Santos Erick Rodrigo da Silva , Dubeux José C. B. , Jaramillo David Mirabedini , Garcia Liza , Vendramini João , DiLorenzo Nicolas , Dantas Queiroz Luana Mayara , Pereira‐Neto José Diógenes , Sousa de Abreu Daciele , Ruiz‐Moreno Martin 
Published: November 2021

AbstractStockpiling limpograss [Hemarthria altissima (Poir.) Stapf & C.E. Hubb.] may be an option to extend the grazing season and decrease the needs for conserved forage in Florida. This 2‐yr study evaluated herbage accumulation (HA), in vitro digestible organic matter (IVDOM), and crude protein (CP) concentrations of four limpograss entries (‘Floralta’, ‘Gibtuck’, ‘Kenhy’, and Entry 1) and ‘Tifton 85′ bermudagrass [Cynodon spp.] during the growth (May–August) and stockpiling (September–January) periods. During the growth period, treatments were the five grasses. During the stockpiling period, treatments were allocated in a split‐plot arrangement with five grasses (main plot) and four stockpiling periods (5, 10, 15, or 20 wk; subplot). Limpograss and Tifton 85 had similar total HA (mean = 8,150 lb dry matter [DM] acre–1) during the growth period, and Gibtuck had greater HA per harvest than Kenhy and Entry 1 (2,360 vs. 1,940 lb DM acre–1, respectively). Regardless of the stockpiling period, HA was similar among treatments. At 15 wk, HA was maximized in both years, despite being similar to 10 and 20 wk in the first year. In general, limpograss had greater IVDOM and lesser CP concentration than Tifton 85 during growth and stockpiling periods. The decline in IVDOM was slower for stockpiled limpograss than Tifton 85, with greater differences occurring at 15 and 20 wk. Stockpiling limpograss may be an alternative to extend the grazing season in livestock operations, however protein supplementation might be needed to maintain or improve animal performance.
Being Positive is Not Everything – Experimental and Computational Studies on the Selectivity of a Self‐Assembled, Multiple Redox‐State Receptor that Binds Anions with up to Picomolar Affinities
Authors: Zubi Ahmed , Alnafisah Hawazin A. , Turega Simon , Marques Igor , Gomes José R. B. , Thomas Jim A. , Félix Vítor 
Published: November 2021

AbstractThe interaction of the self‐assembled trinuclear ruthenium bowl13+, that displays three other accessible oxidation states, with oxo‐anions is investigated. Using a combination of NMR and electrochemical experimental data, estimates of the binding affinities of14+,15+, and16+for both halide and oxo‐anions were derived. This analysis revealed that, across the range of oxidation states of the host, both high anion binding affinities (>109 M−1for specific guests bound to16+) and high selectivities (a range of >107 M−1) were observed. As the crystal structure of binding of the hexafluorophosphate anion revealed that the host has two potential binding sites (named the α and β pockets), the host‐guest properties of both putative binding sites of the bowl, in all of its four oxidation states, were investigated through detailed quantum‐based computational studies. These studies revealed that, due to the interplay of ion‐ion interactions, charge‐assisted hydrogen‐bonding and anion‐π interactions, binding to the α pocket is generally preferred, except for the case of the relatively large and lipophilic hexafluorophosphate anionic guest and the host in the highest oxidation states, where the β pocket becomes relatively favourable. This analysis confirms that host‐guest interactions involving structurally complex supramolecular architectures are driven by a combination of non‐covalent interactions and, even in the case of charged binding pairs, simple ion‐ion interactions alone cannot accurately define these recognition processes.
Comprehensive Structural Analysis of the Bitter Components in Beer by the HPLC‐Assisted Crystalline Sponge Method
Authors: Taniguchi Yoshimasa , Kikuchi Takashi , Sato Sota , Fujita Makoto 
Published: November 2021

AbstractTrans‐iso‐α‐acid is one of the main contributors to the bitter taste of fresh beer and is known to transform into various derivatives during beer aging. However, structural characterization of the derivatives has been a challenging task because of the formation of too many components. Herein, we report that most of the transformation products of trans‐iso‐α‐acid, isolated in this study in only small quantities by HPLC, can be structurally analyzed with the crystalline sponge method. Thirteen compounds, including eight that were previously unreported, have been successfully isolated and analyzed with complete assignment of their absolute configuration. This provides an improved understanding of the chemical transformations that occur during beer aging.
One‐Pot Direct Oxidation of Primary Amines to Carboxylic Acids through Tandem ortho‐Naphthoquinone‐Catalyzed and TBHP‐Promoted Oxidation Sequence
Authors: Si Tengda , Kim Hun Young , Oh Kyungsoo 
Published: November 2021

AbstractBiomimetic oxidation of primary amines to carboxylic acids has been developed where the copper‐containing amine oxidase (CuAO)‐like o‐NQ‐catalyzed aerobic oxidation was combined with the aldehyde dehydrogenase (ALDH)‐like TBHP‐mediated imine oxidation protocol. Notably, the current tandem oxidation strategy provides a new mechanistic insight into the imine intermediate and the seemingly simple TBHP‐mediated oxidation pathways of imines. The developed metal‐free amine oxidation protocol allows the use of molecular oxygen and TBHP, safe forms of oxidant that may appeal to the industrial application.
Ag‐Coupled Polymeric Nanohybrids with Synergistic Photodynamic and Photothermal Activities for Advanced Antibacterial Therapy
Authors: Liu Bei , Liu Yafang , Qin Jinglei , Peng Hongshang 
Published: November 2021

AbstractConsidering the implications of inherent resistance of pathogenic bacteria, it is important to design a new generation of nonchemotherapic nanoagents for effective antibacterial therapy. Herein, we illustrate a one‐step reprecipitation‐encapsulation strategy to incorporate hydrophobic photosensitizers (ZnPc) and photothemal agents (dopamine hydrochloride) with a cationic poly‐L‐lysine (PLL) layer. Upon light irradiation, the polymeric nanohybrid exhibits high photo‐to‐thermal conversion efficiency (30.3%) and effective 1O2 generation capability. To further enhance the antibacterial efficiency, Ag nanoparticle, a typical broad‐spectrum antibacterial agent, was decorated on the surface of PLL layer by in‐situ reduction. The as‐synthesized nanohybrids, referred to as ZnPc/DA@Ag, achieved a robust photodynamic/photothermal/Ag antibacterial capability without apparent systemic toxicity, thus holding great potential for broad‐spectrum eradication of pathogenic bacteria.
Strong Structural and Electronic Binding of Bovine Serum Albumin to ZnO via Specific Amino Acid Residues and Zinc Atoms
Authors: Hematian Hadi , Ukraintsev Egor , Rezek Bohuslav 
Published: November 2021

AbstractZnO biointerfaces with serum albumin have attracted noticeable attention due to the increasing interest in developing ZnO‐based materials for biomedical applications. ZnO surface morphology and chemistry are expected to play a critical role on the structural, optical, and electronic properties of albumin‐ZnO complexes. Yet there are still large gaps in the understanding of these biological interfaces. Herein we comprehensively elucidate the interactions at such interfaces by using atomic force microscopy and nanoshaving experiments to determine roughness, thickness, and adhesion properties of BSA layers adsorbed on the most typical polar and non‐polar ZnO single‐crystal facets. These experiments are corroborated by force field (FF) and density‐functional tight‐binding (DFTB) calculations on ZnO‐BSA interfaces. We show that BSA adsorbs on all the studied ZnO surfaces while interactions of BSA with ZnO are found to be considerably affected by the atomic surface structure of ZnO. BSA layers on thesurface have the highest roughness and thickness, hinting at a specific upright BSA arrangement. BSA layers onsurface have the strongest binding, which is well correlated with DFTB simulations showing atomic rearrangement and bonding between specific amino acids (AAs) and ZnO. Besides the structural properties, the ZnO interaction with these AAs also controls the charge transfer and HOMO‐LUMO energy positions in the BSA‐ZnO complexes. This ZnO facet‐specific protein binding and related structural and electronic effects can be useful for improving the design and functionality of ZnO‐based materials and devices.
Naphthalenyl‐Substituted α,α′‐Bisimino‐2,3 : 5,6‐Bis(pentamethylene)pyridines as Thermally Robust Supports for Iron Ethylene Polymerization Catalysts
Authors: Lin Wenhua , Zhang Liping , Solan Gregory A. , Ma Yanping , Liang Tongling , Sun Wen‐Hua 
Published: November 2021

AbstractSix examples of N,N,N‐chelated iron(II) chloride complex, [2,3 : 5,6‐{C4H8C(NAr)}2C5H3N]FeCl2 (Ar=1‐C10H7 Fe1, 2‐Me‐1‐C10H6 Fe2, 2‐(CHMePh)‐1‐C10H6 Fe3, 2‐Cl‐1‐C10H6 Fe4, 4‐Br‐1‐C10H6 Fe5, 4‐NO2‐1‐C10H6 Fe6), differing in the steric/electronic properties of the substituents appended to the N‐naphthalen‐1‐yl groups, have been synthesized in reasonable yield via a facile one‐pot route. The molecular structure of five‐coordinate Fe3 emphasizes the steric hindrance imposed on the iron center by the CHMePh‐substituted bicyclic aromatic groups. With either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) as activator, the complexes displayed a wide range in catalytic activities for ethylene polymerization with the order for MMAO being: Fe3>Fe2≫Fe1>Fe4≫Fe5 while Fe6 was almost inactive. In particular, Fe3/MMAO exhibited exceptionally high activity at 70 °C (up to 15.7×106 g (PE) mol−1 (Fe) h−1) affording low molecular weight (2.97 kg mol−1) polyethylene of high linearity and narrow dispersity (Mw/Mn=1.38). Moreover, the same catalyst displayed excellent thermostability by maintaining high activity at 90 °C (up to 9.26×106 g (PE) mol−1 (Fe) h−1). Similar activity trends were observed with MAO though the catalysts were in general less active but formed distinctly higher molecular weight polyethylene.
Substituent Dependent Cyclization Reactions of 1,1'‐Bis(alkynyl)ferrocenes with the (C6F5)BH2 ⋅ SMe2 Hydroboration Reagent
Authors: Škoch Karel , Daniliuc Constantin G. , Kehr Gerald , Erker Gerhard 
Published: November 2021

AbstractThe reaction of 1,1'‐bis(tert‐butylethynyl)ferrocene (4 a) with the (C6F5)BH2 ⋅ SMe2 reagent results in two‐fold hydroboration to give the boron containing [3]ferrocenophane 5. It reacts with xylylisocyanide by insertion into the boron‐carbon bond to give the ring enlarged boron containing [4]ferrocenophane derivative 8. 1,1'‐Bis(trimethylsilylethynyl)ferrocene (4 b) undergoes the hydroboration reaction with (C6F5)BH2 with inverted regioselectivity. This results in the formation of the 16‐membered dimeric bis‐boron containing macrocyclic bridged bis‐ferrocene system 10.