bluuebunny/crossref_metadata_2025_split huggingface dataset:
Taylor‐Couette reactor: Principles, design, and applications
Authors: Schrimpf Marco , Esteban Jesús , Warmeling Helge , Färber Tobias , Behr Arno , Vorholt Andreas J. 
Published: February 2021

AbstractThe Taylor‐Couette reactor (TCR) is an apparatus that capitalizes on the Taylor‐Couette flow, which allows many flow regimes and conditions to perform (bio‐)chemical conversions with precise control of various reactor characteristics. With the possibility to continuously perfuse the reactor with a reaction medium, the TCR becomes interesting for chemical engineering applications. In this review, we introduce this reactor type and provide an overview of its history, principles of the flow regimes, and a description and design aspects of the reactors and their elements. Available information in the literature is summarized and harmonized to present available formulas and correlations in a consistent set of variables. Additionally, a wide number of applications in process technology are covered, including reactions in homogeneous, photo, and enzymatic catalysis, polymer synthesis, and crystallization and aggregation‐flocculation processes. Focusing on this reactor configuration, this article intends to be used as a hub for scientific groups interested in TCRs.
Mathematical modeling and parameter estimation of MFI membranes for para/ortho‐xylene separation
Authors: Liu Jingjun , McCool Benjamin , Johnson J. R. , Rangnekar Neel , Daoutidis Prodromos , Tsapatsis Michael 
Published: February 2021

AbstractA mathematical model of a membrane with a thin, oriented, and selective MFI layer, which also includes contributions from defects, pore blockages, support layer, and external mass transfer, was formulated based on the Maxwell‐Stefan equations. It was validated using reported (Kim et al., Angew Chemie Int Ed, 2018, 57:480–485; Jeon et al., Nature, 2017, 543:690–694) para/ortho‐xylene separation data from five MFI membranes. The diffusivities of the xylenes were considered to be the same for all membranes, while the thickness and the density of defects and pore blockage were treated as unique properties of each membrane, and their contributions were estimated by fitting the model to the corresponding separation data. The effects of these properties and the role of permeate pressure on the separation performance were subsequently analyzed. The proposed modeling, parameter estimation, and analysis framework allow one to quantitatively interpret the variation of separation performance, to understand separation bottlenecks, and to provide guidance for designing membranes with desired performance.
On the trail of primate scent signals: A field analysis of callitrichid scent‐gland secretions by portable gas chromatography‐mass spectrometry
Authors: Poirier Alice C. , Waterhouse John S. , Watsa Mrinalini , Erkenswick Gideon A. , Moreira Laís A. A. , Tang Jia , Dunn Jacob C. , Melin Amanda D. , Smith Andrew C. 
Published: February 2021

AbstractChemosignals are mediators of social interactions in mammals, providing con‐ and hetero‐specifics with information on fixed (e.g., species, sex, group, and individual identity) and variable (e.g., social, reproductive, and health status) features of the signaler. Yet, methodological difficulties of recording and quantifying odor signals, especially in field conditions, have hampered studies of natural systems. We present the first use of the Torion® portable gas chromatography‐mass spectrometry (GC‐MS) instrument for in situ chemical analysis of primate scents. We collected and analyzed swab samples from the scent glands and skin from 13 groups (57 individuals) of two sympatric species of wild emperor tamarins,Saguinus imperator, and Weddell's saddleback tamarins,Leontocebus weddelli(Callitrichidae). In total, 11 compounds of interest (i.e., probably derived from the animals) could be detected in the samples, with 31 of 215 samples containing at least one compound of interest. The composition of these 31 samples varied systematically with species, group, sex, and breeding status. Moreover, we tentatively identified seven of the compounds of interest as methyl hexanoate, benzaldehyde, ethyl hexanoate, acetophenone, a branched C15 alkane, 4‐methoxybenzaldehyde, and hexadecan‐1‐ol. As the field of primate semiochemistry continues to grow, we believe that portable GC‐MS instruments have the potential to help make progress in the study of primate chemosignaling in field conditions, despite limitations that we encountered. We further provide recommendations for future use of the Torion® portable GC‐MS for in situ analyses.
A Dual Fluorescence–Spin Label Probe for Visualization and Quantification of Target Molecules in Tissue by Multiplexed FLIM–EPR Spectroscopy
Authors: Dong Pin , Stellmacher Johannes , Bouchet Lydia M. , Nieke Marius , Kumar Amit , Osorio‐Blanco Ernesto R. , Nagel Gregor , Lohan Silke B. , Teutloff Christian , Patzelt Alexa , Schäfer‐Korting Monika , Calderón Marcelo , Meinke Martina C. , Alexiev Ulrike 
Published: February 2021

AbstractSimultaneous visualization and concentration quantification of molecules in biological tissue is an important though challenging goal. The advantages of fluorescence lifetime imaging microscopy (FLIM) for visualization, and electron paramagnetic resonance (EPR) spectroscopy for quantification are complementary. Their combination in a multiplexed approach promises a successful but ambitious strategy because of spin label‐mediated fluorescence quenching. Here, we solved this problem and present the molecular design of a dual label (DL) compound comprising a highly fluorescent dye together with an EPR spin probe, which also renders the fluorescence lifetime to be concentration sensitive. The DL can easily be coupled to the biomolecule of choice, enabling in vivo and in vitro applications. This novel approach paves the way for elegant studies ranging from fundamental biological investigations to preclinical drug research, as shown in proof‐of‐principle penetration experiments in human skin ex vivo.
Electrochemical Radical Silyl‐Oxygenation of Activated Alkenes
Authors: Ke Jie , Liu Wentan , Zhu Xujiang , Tan Xingfa , He Chuan 
Published: February 2021

AbstractAn efficient electrochemical radical silyl‐oxygenation of electron‐deficient alkenes is demonstrated, which gives access to a variety of new highly functionalized silicon‐containing molecules, including β‐silyl‐cyanohydrin derivatives in good yields with excellent chemo‐ and regio‐selectivity. This electrochemical radical silylation process conducts under mild conditions without the use of transition metal catalyst or chemical oxidant and exhibits a wide scope of substrate silanes with high functional‐group tolerance. The ability to access silyl radicals using electrochemical Si−H activation offers new perspectives for the synthesis of valuable organosilicon compounds in a sustainable and green manner.
Cascaded Excited‐State Intramolecular Proton Transfer Towards Near‐Infrared Organic Lasers Beyond 850 nm
Authors: Wu Jun‐Jie , Zhuo Ming‐Peng , Lai Runchen , Zou Sheng‐Nan , Yan Chang‐Cun , Yuan Yi , Yang Sheng‐Yi , Wei Guo‐Qing , Wang Xue‐Dong , Liao Liang‐Sheng 
Published: February 2021

AbstractNear‐infrared (NIR) organic solid‐state lasers play an essential role in applications ranging from laser communication to infrared night vision, but progress in this area is restricted by the lack of effective excited‐state gain processes. Herein, we originally proposed and demonstrated the cascaded occurrence of excited‐state intramolecular proton transfer for constructing the completely new energy‐level systems. Cascading by the first ultrafast proton transfer of <430 fs and the subsequent irreversible second proton transfer of ca. 1.6 ps, the stepwise proton transfer process favors the true six‐level photophysical cycle, which supports efficient population inversion and thus NIR single‐mode lasing at 854 nm. This work realizes longest wavelength beyond 850 nm of organic single‐crystal lasing to date and originally exploits the cascaded excited‐state molecular proton transfer energy‐level systems for organic solid‐state lasers.
Diastereoselective and Stereodivergent Synthesis of 2‐Cinnamylpyrrolines Enabled by Photoredox‐Catalyzed Iminoalkenylation of Alkenes
Authors: Shen Xu , Huang Congcong , Yuan Xiang‐Ai , Yu Shouyun 
Published: February 2021

AbstractA photoredox‐catalyzed iminoalkenylation of γ‐alkenyl O‐acyl oximes has been developed. Readily available alkenylboronic acids serve as alkenylation reagents, leading to densely functionalized pyrrolines. Both (E)‐ and (Z)‐cinnamylpyrrolines are accessible depending on the reaction solvent. In dichloromethane, (E)‐cinnamylpyrrolines are produced through a photoredox‐mediated single‐electron‐transfer process. In tetrahydrofuran, (Z)‐cinnamylpyrrolines are generated by photocatalytic contra‐thermodynamic E‐to‐Z isomerization of (E)‐cinnamylpyrrolines though an energy‐transfer pathway. Two stereocenters are established with complete diastereoselectivity and only one diastereomer is isolated.
A Visible‐Light‐Harvesting Covalent Organic Framework Bearing Single Nickel Sites as a Highly Efficient Sulfur–Carbon Cross‐Coupling Dual Catalyst
Authors: Chen Hui , Liu Wanlu , Laemont Andreas , Krishnaraj Chidharth , Feng Xiao , Rohman Fadli , Meledina Maria , Zhang Qiqi , Van Deun Rik , Leus Karen , Van Der Voort Pascal 
Published: February 2021

AbstractCovalent Organic Frameworks (COFs) have recently emerged as light‐harvesting devices, as well as elegant heterogeneous catalysts. The combination of these two properties into a dual catalyst has not yet been explored. We report a new photosensitive triazine‐based COF, decorated with single Ni sites to form a dual catalyst. This crystalline and highly porous catalyst shows excellent catalytic performance in the visible‐light‐driven catalytic sulfur–carbon cross‐coupling reaction. Incorporation of single transition metal sites in a photosensitive COF scaffold with two‐component synergistic catalyst in organic transformation is demonstrated for the first time.
Metal‐Coordinated Supramolecular Polymers from the Minimalistic Hybrid Peptide Foldamers
Authors: Dey Sanjit , Misra Rajkumar , Saseendran Abhijith , Pahan Saikat , Gopi Hosahudya N. 
Published: February 2021

AbstractAvailing the peptide folded architectures to design metal‐coordinated frameworks and cages is restricted due to the scarcity of readily accessible short and stable secondary structures. The secondary structures, α‐helix and β‐sheets, play significant roles in stabilizing tertiary folds of proteins. Designing such helical structures from the short sequences of peptides without having any steric restrictions is exceptionally challenging. Here we reveal the short α,γ‐hybrid tripeptide sequences that manifest stable helical structures without having any sterically constrained amino acids. These short hybrid tripeptides fold into helices even in the presence of two typically β‐sheet favoring Val residues. The hybrid helix consisting of terminal pyridine units coordinates with the metal ions and drives the helical polymerization. Depending on the sequence and the position of N in pyridine moieties, these peptides form selective metallogels with Ag+ and Cu2+ ions. The X‐ray diffracted analysis of the peptide single crystals obtained from the gel matrix reveals that the helical structure is maintained during the self‐assembly process. Further, by varying the counter anion, a 3D helical crystalline coordination polymer with permanent porosity is generated. The findings reported here can be used to design new functional metal‐foldamer coordinated polymers.
Dynamically Re‐Organized Collagen Fiber Bundles Transmit Mechanical Signals and Induce Strongly Correlated Cell Migration and Self‐Organization
Authors: Fan Qihui , Zheng Yu , Wang Xiaochen , Xie Ruipei , Ding Yu , Wang Boyi , Yu Xiaoyu , Lu Ying , Liu Liyu , Li Yunliang , Li Ming , Zhao Yuanjin , Jiao Yang , Ye Fangfu 
Published: February 2021

AbstractCorrelated cell migration in fibrous extracellular matrix (ECM) is important in many biological processes. During migration, cells can remodel the ECM, leading to the formation of mesoscale structures such as fiber bundles. However, how such mesoscale structures regulate correlated single‐cells migration remains to be elucidated. Here, using a quasi‐3D in vitro model, we investigate how collagen fiber bundles are dynamically re‐organized and guide cell migration. By combining laser ablation technique with 3D tracking and active‐particle simulations, we definitively show that only the re‐organized fiber bundles that carry significant tensile forces can guide strongly correlated cell migration, providing for the first time a direct experimental evidence supporting that matrix‐transmitted long‐range forces can regulate cell migration and self‐organization. This force regulation mechanism can provide new insights for studies on cellular dynamics, fabrication or selection of biomedical materials in tissue repairing, and many other biomedical applications.
Activation of Pyroptosis by Membrane‐Anchoring AIE Photosensitizer Design: New Prospect for Photodynamic Cancer Cell Ablation
Authors: Wu Min , Liu Xingang , Chen Huan , Duan Yukun , Liu Jingjing , Pan Yutong , Liu Bin 
Published: February 2021

AbstractPyroptosis as a lytic and inflammatory form of cell death is a powerful tool to fight against cancer. However, pyroptosis is usually activated by chemotherapeutic drugs, which limits its anti‐tumor applications due to drug resistance and severe side effects. Herein, we demonstrate that membrane targeting photosensitizers can induce pyroptosis for cancer cell ablation with noninvasiveness and low side effects. A series of membrane anchoring photosensitizers (TBD‐R PSs) with aggregation‐induced emission (AIE) characteristics were prepared through conjugation of TBD and phenyl ring with cationic chains. Upon light irradiation, cytotoxic ROS were produced in situ, resulting in direct membrane damage and superior cancer cell ablation. Detailed study revealed that pyroptosis gradually became the dominant cell death pathway along with the increase of TBD‐R PSs membrane anchoring capability. This study offers a photo‐activated pyroptosis‐based intervention strategy for cancer cell ablation.
Significantly enhanced the properties of PE/GO composites with segregated structures via two‐step compound
Authors: Cao Jiandong , Ren Shangyuan , Xin Shixuan , Bai Yongxiao , Wang Wenjie , Gao Wensheng 
Published: February 2021

AbstractConductive polymer composites (CPCs) have generated significant academic and industrial interest due to the wide applications in anti‐static materials, electromagnetic interface, sensor, and conductors. Nonetheless, the CPCs fabricated by conventional melt‐mixing applied to the scalable production generally have a very high percolation threshold, which always suffer from the various draw backs such as, high melt viscosities, low economic affordability, inferior mechanical properties, and solution compounding by reducing the viscosity improves the uniformity of nano‐particles. This work aims at building a segregated structure in polyethylene to enhance mechanical properties and electrical conductivity, by taking advantage of the solution compounding and melt‐blending methods. Based on the segregated structure, the composites showed the enhanced mechanical properties, thermal stabilities and antistatic properties with a low percolation threshold. In addition, the composite mechanism between graphene oxide and polyethylene and the structure‐performance relationship of the CPCs were elucidated and explored by SEM, TEM, and FTIR.
Structurally modified electrospun poly(methyl methacrylate) nanofibers as advanced host matrices for PbS quantum dots
Authors: Philip Princy , Jose Tomlal , Vanchippurackal Ison V. 
Published: February 2021

AbstractThe present work deals with the studies of the host matrix nature of pure and structurally modified surface roughened and coaxial hollow electrospun poly(methyl methacrylate) (PMMA) nanofibers to lead sulphide (PbS) quantum dots. The various structural and molecular analyses conducted on these samples proved the advancements and structural modifications made in the properties of pure PMMA nanofibers by electrospinning and selective dissolution. The successful incorporation of the quantum dots to pure and structurally modified PMMA nanofibers and hence the host matrix nature of these nanofibers is proved by different spectral analyses of the samples. The coaxial hollow PMMA nanofibers are found to be the best host matrix among these PMMA nanofibers as proved by the optical studies of the samples. Photoluminescence analyses of the samples showed the influence of these quantum dots on the optical properties of PMMA nanofibers. It is observed here that, the quantum dots enhance the intensity of coaxial hollow PMMA nanofibers to about four times than its virgin form. The pure and structurally modified PMMA nanofibers incorporated with PbS quantum dots are proved to be efficient for the degradation of methylene blue dye where coaxial hollow PMMA nanofibers incorporated with PbS quantum dots is the best.
Developing antibacterial surgical adhesives: An enhancement of cyanoacrylate polymers
Authors: Stevens Rhianna , Esteban Gabrielle , Jenkins Emma , Saitow Cassandra , Gurney Rich 
Published: February 2021

AbstractSurgical site infections (SSIs) and traumatic wounds have a significant risk of becoming contaminated by microbial pathogens of both endogenous and nosocomial origins, including Staphylococcus aureus and Enterococci sp.. One preventative approach is to protect wounds from infection by using a rapidly curing adhesive to seal the wound and prevent further contamination. Here, we demonstrate the covalent incorporation of an antimicrobial, quaternary ammonium chloride monomer (quat) into a 2‐octyl cyanoacrylate (2oc) polymer adhesive. Copolymerization was confirmed via nuclear magnetic resonance spectroscopy. Cytotoxicity of the copolymer was assessed against: S. epidermidis and E. coli, and 3T3 mouse fibroblasts. The CA‐Quat polymer was found to exhibit dose‐dependent bacteriostatic and bactericidal effects against both E. coli and S. epidermidis, importantly without showing any demonstrable toxicity against mammalian 3T3 fibroblast cells. The described experiments provide promising data to suggest successful copolymerization, effective antibacterial properties, and remarkably low cytotoxic effects of the copolymer on mammalian cells.
Hybrid anion exchange membranes with adjustable ion transport channels designed by compounding SEBS and homo‐polystyrene
Authors: Shi Yue , Meng Fanzhi , Zhao Zhongfu , Liu Wei , Zhang Chunqing 
Published: February 2021

AbstractHybrid anion exchange membranes (AEMs) were prepared via chemically functionalizing and crosslinking poly(styrene‐b‐[ethylene‐co‐butylene]‐b‐styrene) (SEBS) copolymers and low molecular weight homo‐polystyrene (hPS). Via sequential chloromethylation, crosslinking, quaternization, and alkalization, a series of hPS/SEBS AEMs were obtained with varying content of hPS. Systematic structural, morphological, mechanical, absorption, and transport measurements reveal that these properties depend on the total PS content in the membranes. Particularly, increasing total PS content causes (a) PS domains in the AEMs transition the cylindrical morphology to lamella‐like morphology with comparable correlation length; (b) Young's modulus, water uptake, swelling ratio, ionic exchange capacity and ionic conductivity of the AEMs, and Tg of PS phase increase. In addition, the alkaline stability of the hPS/SEBS AEMs is also improved by addition of hPS. These findings suggest that the proposed method can develop high performance SEBS AEMs that are suitable for fuel cell applications.
Improvement in mechanical, electrical, and shape memory properties of the polystyrene‐based carbon fiber‐reinforced polymer composites containing carbon nanotubes
Authors: Erkmen Berrak , Bayram Goknur 
Published: February 2021

AbstractCarbon fiber‐reinforced polymers based on polystyrene matrix containing elastomer and carbon nanotubes (CNTs) were produced by compression molding. The effects of carbon fabric (CF) concentration and silane treatment on the morphology, mechanical, electrical, and shape memory properties of the multilayer composites were investigated. The SEM analyses showed that fibers of the silane‐treated CFs were more homogeneously covered with the polymer layers than the untreated CFs. The tensile strength and modulus of the composites increased by 521% and 125%, respectively, with an increasing number of CF plies from one to five. Upon silane treatment, the tensile strength of the multilayer composite improved by 26%, and the tensile modulus decreased by 18.4%. Electrical conductivities of the composites were in the semiconductor region due to the presence of both CNTs and CFs. 100% shape recovery less than a minute recovery time was obtained for all the composites with electrically triggered bending test.
A modified Mask region‐based convolutional neural network approach for the automated detection of archaeological sites on high‐resolution light detection and ranging‐derived digital elevation models in the North German Lowland
Authors: Bonhage Alexander , Eltaher Mahmoud , Raab Thomas , Breuß Michael , Raab Alexandra , Schneider Anna 
Published: February 2021

AbstractDue to complicated backgrounds and unclear target orientation, automated object detection is difficult in the field of archaeology. Most of the current convolutional neural network (CNN) object‐oriented detection techniques are based on a faster region‐based CNN (R‐CNN) and other one‐stage detectors that often lack adequate processing speeds and detection accuracies. Recently, the two‐stage detector Mask R‐CNN technique achieved impressive results in object detection and instance segmentation problems and was successfully applied in the analysis of archaeological airborne laser scanning (ALS) data. In this study, we outline a modified Mask R‐CNN technique that reliably and efficiently detects relict charcoal hearth (RCH) sites on light detection and ranging (LiDAR) data‐based digital elevation models (DEMs). Using image augmentation and image preprocessing steps combined with the deep learning‐based adaptive gradient method with a dynamic bound on the learning rate (AdaBound) optimization technique, we could improve the model's accuracy and significantly reduce its training time. We use DEMs based on high‐resolution LiDAR data and the visualization for archaeological topography (VAT) technique that give images with a very strong contrast of the terrain and the outline of the sites of interest in the North German Lowland. Therefore, the model can identify RCH sites with an average recall of 83% and an average precision of 87%. Techniques such as the modified Mask R‐CNN method outlined here will help to greatly improve our knowledge about archaeological site densities in the realm of historical charcoal production and past human‐landscape interactions. This method provides an accurate, time‐efficient and bias‐free large‐scale site mapping option not only for the North German Lowland but potentially for other landscapes as well.