bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Noncovalent Photoswitch for Photochemical Regulation of Enzymatic Activity
Authors: Chai Jingshan , Zhao Yu , Xu Lina , Li Qiushi , Hu Xin‐Yue , Guo Dong‐Sheng , Liu Yang 
Published: April 2022

AbstractPhotochemical regulation provides a promising approach for controlling enzyme activity on demand owing to its high spatiotemporal resolution. However, reversible regulation of the enzyme activity by light usually requires genetic mutations and covalent modifications of the target enzymes, which may lead to irreversible changes in the enzyme structure and subsequent loss of the enzymatic activity. Herein, we have developed a novel strategy based on a polymeric inhibitor‐encapsulated enzyme, which noncovalently anchors the azobenzene‐modified inhibitors to the enzyme active site, thereby achieving reversible control of the activity of native enzymes using light. As neither genetic mutation nor chemical modification of enzymes is required for this method, negligible loss of the enzymatic activity was observed for the encapsulated enzymes compared to their native counterparts. Thus, this approach has demonstrated a promising strategy for achieving reversible regulation of the activity of native enzymes.
A Ruthenium(II) Polypyridyl Complex Disrupts Actin Cytoskeleton Assembly and Blocks Cytokinesis
Authors: Gill Martin R. , Jarman Paul J. , Hearnden Vanessa , Fairbanks Simon D , Bassetto Marcella , Maib Hannes , Palmer John , Ayscough Kathryn R. , Thomas Jim A. , Smythe Carl 
Published: April 2022

AbstractThe dinuclear RuII complex [(Ru(phen)2)2(tpphz)]4+ (phen=1,10‐phenanthroline, tpphz=tetrapyridophenazine) “RuRuPhen” blocks the transformation of G‐actin monomers to F‐actin filaments with no disassembly of pre‐formed F‐actin. Molecular docking studies indicate multiple RuRuPhen molecules bind to the surface of G‐actin but not the binding pockets of established actin polymerisation inhibitors. In cells, addition of RuRuPhen causes rapid disruption to actin stress fibre organisation, compromising actomyosin contractility and cell motility; due to this effect RuRuPhen interferes with late‐stage cytokinesis. Immunofluorescent microscopy reveals that RuRuPhen causes cytokinetic abscission failure by interfering with endosomal sorting complexes required for transport (ESCRT) complex recruitment.
Strain of Supramolecular Interactions in Single‐Stacking Junctions
Authors: Li Ruihao , Zhou Yu , Ge Wenhui , Zheng Jueting , Zhu Yixuan , Bai Jie , Li Xiaohui , Lin Luchun , Duan Huicong , Shi Jia , Yang Yang , Liu Junyang , Liu Zitong , Hong Wenjing 
Published: April 2022

AbstractSupramolecular electronics provide opportunities to integrate molecular building blocks into electronic circuits, and investigations of the mechanical properties of the non‐covalent interactions are necessary to understand the role of the assembly configuration in the electronic coupling among different assembly blocks. However, the mechanical characterization of supramolecular interactions remains experimentally challenging. We investigated the strain distribution of the supramolecular interactions through a series of single‐stacking junctions. The alpha values exhibit a clear odd‐even effect versus the numbers of thiophene rings. The theoretical calculations demonstrated that a larger rotational barrier of the single‐stacking junctions with an even number of thiophene rings leads to limited torsional freedom and thus a smaller strain distribution. These results provide new insights into the control of supramolecular interactions by the design of the basic molecular building blocks.
Total Synthesis of (+)‐Cochlearol B by an Approach Based on a Catellani Reaction and Visible‐Light‐Enabled [2+2] Cycloaddition**
Authors: Richardson Alistair D. , Vogel Trenton R. , Traficante Emily F. , Glover Kason J. , Schindler Corinna S. 
Published: April 2022

AbstractA 14‐step synthesis of (+)‐cochlearol B is reported. This renoprotective meroterpenoid features a unique core structure containing a densely substituted cyclobutane ring with three stereocenters. Our strategy employed an organocatalytic Kabbe condensation in route to the key chromenyl triflate. A subsequent Catellani reaction incorporated the remaining carbon atoms featured in the skeleton of cochlearol B. An ensuing visible‐light‐mediated [2+2] photocycloaddition closed the cyclobutane and formed the central bicyclo[3.2.0]heptane core. Notably, careful design and tuning of the Catellani and photocycloaddition reactions proved crucial in overcoming undesired reactivity, including cyclopropanation reactions and [4+2] cycloadditions.
Diastereoselective Transfer of Tri(di)fluoroacetylsilanes‐Derived Carbenes to Alkenes
Authors: Zhang Yizhi , Zhou Gang , Gong Xingxing , Guo Zhuanzhuan , Qi Xiaotian , Shen Xiao 
Published: April 2022

AbstractStereoselective cyclopropanation reaction of alkenes is usually achieved by metal complexes via singlet‐metal‐carbene intermediates. However, previous transition‐metal‐catalyzed cyclopropanation of alkenes with acylsilanes afforded low diastereoselectivity. Herein, we report the first visible‐light‐induced transition‐metal‐free cyclopropanation reaction of terminal alkenes with trifluoroacetylsilanes and difluoroacetylsilanes. Both aromatic and aliphatic alkenes as well as electron‐deficient alkenes are suitable substrates for the highlycis‐selective [2+1] cyclization reaction. A combination of experimental and computational studies identified triplet carbenes as being key intermediates in this transformation. The gram scale reaction and late‐stage functionalization demonstrated the synthetic potential of this strategy.
Activation of Main‐Group Antimony Atomic Sites for Oxygen Reduction Catalysis
Authors: Gu Yu , Xi Baojuan J. , Zhang Hua , Ma Yuchen C. , Xiong Shenglin L. 
Published: April 2022

AbstractThe catalytic activity of main‐group metal is hard to promote because of the intrinsic lack of host d orbitals available to be combined. Herein, under the guidance of theoretical predictions, we find atom‐dispersed antimony sites (Sb−N4 moieties) can be activated to achieve high oxygen reduction reaction (ORR) activity using a functional group regulation strategy. Correspondingly, we manage to synthesize a main‐group Sb single‐atom catalysts (SACs) that comprises Sb−N4 active moieties functionalized by epoxy groups in the second microenvironment and incorporated in N‐doped graphene (Sb1/NG(O)). The electron‐rich epoxy group can adjust the electronic structure of Sb−N4 active moieties, thereby optimizing the adsorption of the intermediate. The Sb SACs are comparable to industrial Pt/C under alkaline conditions. This discovery provides new opportunities to manipulate and improve the catalytic activity of main‐group‐element electrocatalysts.
Sequential Allylic Alcohol Formation by a Multifunctional Cytochrome P450 Monooxygenase with Rare Redox Partners
Authors: Kim Hak Joong , Ishida Keishi , Ishida‐Ito Mie , Hertweck Christian 
Published: April 2022

AbstractCaryoynencin is a toxic and antifungal fatty acid derivative produced by a number of plant‐pathogenic and insect‐protective bacteria (Trinickia caryophylli and Burkholderia spp.). In addition to the reactive tetrayne unit, the presence of an allylic alcohol moiety is critical for antimicrobial activities. By a combination of mutational analyses, heterologous expression and in vitro reconstitution experiments we show that the cytochrome P450 monooxygenase CayG catalyzes the complex transformation of a saturated carbon backbone into an allylic alcohol. Unexpectedly, CayG employs a ferritin‐like protein (CayK) or a rubredoxin (CayL) component for electron transport. A desaturation‐hydroxylation sequence was deduced from a time‐course study and in vitro biotransformations with pathway intermediates, substrate analogues, protegencin congeners from Pseudomonas protegens Pf‐5, and synthetic derivatives. This unusual multifunctional oxygenase may inspire future biocatalytic applications.
Herstellung von benzylischen Natrium‐Metallorganylen im kontinuierlichen Durchfluss
Authors: Harenberg Johannes H. , Reddy Annapureddy Rajasekar , Karaghiosoff Konstantin , Knochel Paul 
Published: April 2022

AbstractWir beschreiben eine laterale Natriierung von Alkali(hetero)arenen mittels bedarfsgerecht generiertem, in Hexan löslichem (2‐Ethylhexyl)natrium (1) in Gegenwart von TMEDA. (2‐Ethylhexyl)natrium (1) wird mittels eines Natrium‐Festbettreaktors hergestellt und für Metallierungen bei Umgebungstemperatur sowohl im Kolben als auch im kontinuierlichem Durchfluss genutzt. Die entstehenden benzylischen Natriumspezies werden nachfolgend mit verschiedenen Elektrophilen, unter anderem Carbonylverbindungen, Epoxiden, Oxetan, Allyl/Benzylchloriden, Alkylhalogenen und ‐tosylaten abgefangen. Wurtz‐Typ‐Kopplungen mit sekundären Alkylhalogenen und Tosylaten laufen unter kompletter Inversion der Stereochemie ab. Des Weiteren wird die Nützlichkeit dieser lateralen Natriierung durch die Synthese pharmazeutisch relevanter Verbindungen demonstriert. So wird Fingolimod durch die zweifache Anwendung der lateralen Natriierung ausgehend von p‐Xylol hergestellt. Zusätzlich ist 7‐fach Isotopen angereichertes Salmeterol‐d7 und Fenpiprane, sowie Ausgangsmaterialien zu super linearen Alkylbenzyl (SLAB) Tensiden hergestellt worden.
Two‐Dimensional Photosensitizer Nanosheets via Low‐Energy Electron Beam Induced Cross‐Linking of Self‐Assembled RuII Polypyridine Monolayers
Authors: Küllmer Maria , Herrmann‐Westendorf Felix , Endres Patrick , Götz Stefan , Reza Rasouli Hamid , Najafidehaghani Emad , Neumann Christof , Gläßner Rebecka , Kaiser David , Weimann Thomas , Winter Andreas , Schubert Ulrich S. , Dietzek‐Ivanšić Benjamin , Turchanin Andrey 
Published: April 2022

AbstractArtificial photosynthesis for hydrogen production is an important element in the search for green energy sources. The incorporation of photoactive units into mechanically stable 2D materials paves the way toward the realization of ultrathin membranes as mimics for leaves. Here we present and compare two concepts to introduce a photoactive RuII polypyridine complex into ≈1 nm thick carbon nanomembranes (CNMs) generated by low‐energy electron irradiation induced cross‐linking of aromatic self‐assembled monolayers. The photoactive units are either directly incorporated into the CNM scaffold or covalently grafted to its surface. We characterize RuII CNMs using X‐ray photoelectron, surface‐enhanced Raman, photothermal deflection spectroscopy, atomic force, scanning electron microscopy, and study their photoactivity in graphene field‐effect devices. Therewith, we explore the applicability of low‐energy electron irradiation of metal complexes for photosensitizer nanosheet formation.
Alteration of the Catalytic Reaction Trajectory of a Vicinal Oxygen Chelate Enzyme by Directed Evolution
Authors: Wang Yi Shuang , Zheng Wan , Jiang Nan , Jin Yun Xia , Meng Zi Kang , Sun Meng Xin , Zong Yu Liang , Xu Tong , Zhu Jiapeng , Tan Ren Xiang 
Published: April 2022

AbstractThe vicinal oxygen chelate (VOC) metalloenzyme superfamily catalyzes a highly diverse set of reactions with the mechanism characterized by the bidentate coordination of vicinal oxygen atoms to metal ion centers, but there remains a lack of a platform to steer the reaction trajectories, especially for o‐quinone metabolizing pathways. Herein, we present the directed‐evolution‐enabled bifunctional turnover of ChaP, which is a homotetramer and represents an unprecedented VOC enzyme class. Unlike the ChaP catalysis of extradiol‐like o‐quinone cleavage and concomitant α‐keto acid decarboxylation, a group of ChaP variants (CVs) catalyze intradiol‐like o‐quinone deconstruction and CO2 liberation from the resulting o‐hydroxybenzoic acid scaffolds with high regioselectivity. Enzyme crystal structures, labeling experiments and computational simulations corroborated that the D49L mutation allows the metal ion to change its coordination with the tyrosine phenoxy atoms in different monomers, thereby altering the reaction trajectory with the regiospecificity further improved by the follow‐up replacement of the Y92 residue with any of alanine, glycine, threonine, and serine. The study highlights the unpredicted catalytic versatility and enzymatic plasticity of VOC enzymes with biotechnological significance.
Trapping X‐ray Radiation Damage from Homolytic Se−C Bond Cleavage in BnSeSeBn Crystals (Bn=benzyl, CH2C6H5)
Authors: Schürmann Christian J. , Teuteberg Thorsten L. , Stückl A. Claudia , Ruth Paul Niklas , Hecker Fabian , Herbst‐Irmer Regine , Mata Ricardo A. , Stalke Dietmar 
Published: April 2022

AbstractIrradiation of dibenzyl diselenide BnSeSeBn with X‐ray or UV‐light cleaves the Se−C and the Se−Se bonds, inducing stable and metastable radical states. They are inevitably important to all natural and life sciences. Structural changes due to X‐ray‐induced Se−C bond‐cleavage could be pin‐pointed in various high‐resolution X‐ray diffraction experiments for the first time. Extended DFT methods were applied to characterize the solid‐state structure and support the refinement of the observed residuals as contributions from the BnSeSe⋅ radical species. The X‐ray or UV‐irradiated crystalline samples of BnSeSeBn were characterized by solid‐state EPR. This paper provides insight that in the course of X‐ray structure analysis of selenium compounds not only organo‐selenide radicals like RSe⋅ may occur, but also organo diselenide BnSeSe⋅ radicals and organic radicals R⋅ are generated, particularly important to know in structural biology.
Dynamic Interconversions of Single Molecules Probed by Recognition Tunneling at Cucurbit[7]uril‐Functionalized Supramolecular Junctions
Authors: Xiao Bohuai , He Suhang , Sun Mingjun , Zhou Jianghao , Wang Zhiye , Li Yunchuan , Liu Simin , Nau Werner M. , Chang Shuai 
Published: April 2022

AbstractWe introduce a versatile recognition tunneling technique using doubly cucurbit[7]uril‐functionalized electrodes to form supramolecular junctions that capture analytes dynamically by host–guest complexation. This results in characteristic changes in their single‐molecule conductance. For structurally related drug molecules (camptothecin, sanguinarine, chelerythrine, and berberine) and mixtures thereof, we observed distinct current switching signals related to their intrinsic conductance properties as well as pH‐dependent effects which can be traced back to their different states (protonated versus neutral). The conductance variation of a single molecule with pH shows a sigmoidal distribution, allowing us to extract a pKa value for reversible protonation, which is consistent with the reported macroscopic results. The new electronic method allows the characterization of unmodified drug molecules and showcases the transfer of dynamic supramolecular chemistry principles to single molecules.
The effects of acetamiprid multigeneration stress on metabolism and physiology of Aphis glycines Matsumura (Hemiptera: Aphididae)
Authors: Zhang Aonan , Xu Ling , Liu Ziqi , Zhang Jiabo , Han Lanlan , Zhao Kuijun 
Published: April 2022

AbstractAphis glycines Matsumura (Hemiptera: Aphididae) is a major soybean pest that often poses a serious threat to soybean production. In this study, we checked the effects of acetamiprid on redox, energy metabolism, and hormone expression in A. glycines. The LC50 and LC30 of acetamiprid were used to treat the fourth instar nymphs in each generation from F0 to F4 to measure the activity of peroxidase, pyruvate kinase, and trehalase using a microassays approach. The peroxidase activity was significantly higher than control when treated with the LC30 of acetamiprid in F2−F5 generations. The activity of pyruvate kinase was significantly higher, while trehalase activity was substantially lower than control in each generation. Besides, we monitored molting and juvenile hormone expression in soybean aphids using enzyme‐linked immunosorbent assay. The juvenile hormone titer of third instar nymphs was significantly higher in the treatment group (F1, F2, F4, and F5), while no effects were noted in the F3 generation. Taken together, the activity of peroxidase and pyruvate kinase in soybean aphid first increased to the peak and then decreased, while the trehalase activity continuously decreased in all generations following exposure to acetamiprid. The juvenile hormone titer was significantly higher, while the molting hormone titer was significantly lower in LC50‐treated aphids than in control. Moreover, the LC30 of acetamiprid increased the molting hormone expression in soybean aphids. These findings indicated a baseline for the effective use of acetamiprid in controlling soybean aphids.
Chiral Cyclopropenimine‐catalyzed Asymmetric Michael Addition of Bulky Glycine Imine to α,β‐Unsaturated Isoxazoles
Authors: Bai Yu‐Jun , Cheng Mei‐Ling , Zheng Xiao‐Hui , Zhang Sheng‐Yong , Wang Ping‐An 
Published: April 2022

AbstractA highly efficient asymmetric Michael addition of bulky glycine imine to α,β‐unsaturated isoxazoles has been achieved by using 5 mol% of chiral cyclopropenimine as a chiral organo‐superbase catalyst under mild conditions. Michael adducts were obtained in excellent yields (up to 97%) and stereoselectivities (up to >99 : 1 dr and 98% ee). A significant solvent effect was found in these chiral organosuperbase catalyzed asymmetric Michael reactions. Gram‐scale preparation of Michael adducts and their transformations are realized to provide corresponding products without loss of stereoselectivities. The configurations of Michael adduct was determined by single‐crystal X‐ray diffraction analysis.
Cannabidiol impairs neural tube closure in mouse whole embryo culture
Authors: Gheasuddin Yosuf , Galea Gabriel L. 
Published: April 2022

AbstractBackgroundCannabidiol (CBD) is a nonpsychoactive constituent of cannabis widely available as a dietary supplement. Previous reports that it impairs the retinoid, sonic hedgehog, and folate metabolism pathways raise concern that it may impair closure of the embryonic neural tube (NT), producing NT defects including spina bifida and exencephaly.MethodsWe undertook teratogenicity testing of CBD in mouse whole embryo culture.ResultsAt concentrations that do not diminish embryo viability, growth, or axial rotation, CBD dose‐dependently impairs cranial NT closure, increasing the proportion of embryos that develop exencephaly. It concomitantly diminishes closure of the spinal NT, the posterior neuropore (PNP), producing longer neuropores at the end of culture which is a hallmark of spina bifida risk. Exposure to CBD does not disrupt the formation of long F‐actin cables in surface ectoderm cells flanking the PNP or folding of the neuroepithelium at predictable hinge points. At the cellular level, CBD exposure does not alter proliferation or apoptosis of the spinal neuroepithelium.DiscussionThus, CBD acts selectively as a neuroteratogen predisposing to spina bifida and exencephaly in mouse whole embryo culture at exposure levels not associated with overt toxicity. Large‐scale testing of CBD's effects on NT closure, particularly in at‐risk groups, is warranted to inform its marketing to women of childbearing age.
Sustainable development, ESG performance and company market value: Mediating effect of financial performance
Authors: Zhou Guangyou , Liu Lian , Luo Sumei 
Published: April 2022

AbstractAt present, more and more attention is paid to the sustainable development of enterprises. In particular, in the context of frequent financial crises and COVID‐19 pandemic, how the performance of listed companies' environmental, social, and governance (ESG) affects the company's market value has attracted widespread attention. Different from existing studies, this paper takes financial performance as a mediating variable and constructs linear regression model and mediating effect model based on analyzing the relationship between ESG performance, financial performance, and company market value and their influencing mechanism. The ESG rating data of Chinese listed companies newly developed by SynTao Green Finance from 2014 to 2019 were selected for empirical test. The results show that the improvement of ESG performance of listed companies can improve the market value of the company, and the financial performance of the company presents an obvious mediating effect. At the same time, operational capacity is an important mediating way for ESG performance to affect the company's market value. Further research shows that ESG performance of state‐owned listed companies exerts a stronger mediating effect on corporate operating capacity. Finally, this paper provides relevant suggestions for regulators, listed companies, and investors.
Planning a robotic competition
Authors: Chatzis Dimitris , Papasalouros Andreas , Kavallieratou Ergina 
Published: April 2022

AbstractEducation changes, and pupils and students require a more active role. Educational competitions could be an answer. This paper highlights the key points as these were revealed through setting up an event of an educational robotic competition from zero. It, also, presents statistics collected in different periods: before the competition, directly after it, and finally at a notable time after the competition (about 6 months). To collect the data, the completion of four different questionnaires, for every annual event, was asked separately, by the participants and the organizers. The paper provides empirical insights on setting up an educational competition. It also outlines the characteristics of the students taking part and underlines the results that the contents have on them. It suggests that teamwork and collaboration within the team is a prerequisite for a competition to have an impact on the educational process. Furthermore, robotic competitions raise the interest of students in robotics, programming, and STEM, while they develop social skills and create bonds between the participants. Moreover, it is a useful tool for educators.
Do honesty‐nudges really work? A large‐scale field experiment in an insurance context
Authors: Martuza Jareef Bin , Skard Siv Rosendahl , Løvlie Lavrans , Thorbjørnsen Helge 
Published: April 2022

AbstractBusinesses want their customers to self‐report information honestly. One increasingly popular way to stimulate desired behavior is by using nudge interventions. But can customers be nudged to self‐report information more honestly? This is currently a debate in the literature, where empirical results are inconclusive. Building on related literature on nudges, we add to this debate with a controlled field experiment (N = 5704). We used data from actual customers making real decisions when they file claims online to a large Nordic insurance provider. To the best of our knowledge, this is the first study to investigate the effects of honesty‐nudges on self‐reported information when filing insurance claims using a controlled field experiment. We designed and tested three honesty‐nudges on insurance customers: (1) signing‐at‐the‐beginning, (2) a descriptive social norm message, and (3) a solidarity message. Across five outcome measures, we found that the honesty‐nudges, standalone or in any possible combination, do not have significant effects in reducing indicators of insurance claims fraud. But interestingly, customers in all treatment groups used significantly more characters to describe losses than customers in the control group. Also, in post hoc analyses, we found signs that the direction of nudge effects varies across customers' age and customer loyalty.