bluuebunny/crossref_metadata_2025_split huggingface dataset:
Loading Linear Arrays of CuII Inside Aromatic Amide Helices
Authors: Wang Jinhua , Wicher Barbara , Méndez‐Ardoy Alejandro , Li Xuesong , Pecastaings Gilles , Buffeteau Thierry , Bassani Dario M. , Maurizot Victor , Huc Ivan 
Published: May 2021

AbstractThe very stable helices of 8‐amino‐2‐quinolinecarboxylic acid oligoamides are shown to uptake CuII ions in their cavity through deprotonation of their amide functions with minimal alteration of their shape, unlike most metallo‐organic structures which generally differ from their organic precursors. The outcome is the formation of intramolecular linear arrays of a defined number of CuII centers (up to sixteen in this study) at a 3 Å distance, forming a molecular mimic of a metal wire completely surrounded by an organic sheath. The helices pack in the solid state so that the arrays of CuII extend intermolecularly. Conductive‐AFM and cyclic voltammetry suggest that electrons are transported throughout the metal‐loaded helices in contrast with hole transport observed for analogous foldamers devoid of metal ions.
Cobalt‐Mediated Switchable Catalysis for the One‐Pot Synthesis of Cyclic Polymers
Authors: Zhao Yajun , Zhu Shuaishuai , Liao Can , Wang Yong , Lam Jacky W. Y. , Zhou Xingping , Wang Xianhong , Xie Xiaolin , Tang Ben Zhong 
Published: May 2021

AbstractA cobalt salen pentenoate complex [salen=(R,R)‐N,N′‐bis(3,5‐di‐tertbutylsalicylidene)‐1,2‐cyclohexanediamine] is rationally designed as the catalyst for the ring‐opening copolymerization (ROCOP) of epoxides/anhydrides/CO2. Via migratory insertion of carbon monoxide (CO) into the Co−O bonds, the ROCOP‐active species α‐alkene‐ω‐O‐CoIII(salen) can be rapidly and quantitatively transformed into α‐alkene‐ω‐O2C‐CoIII(salen) telechelic linear precursors. Upon dilution of reaction mixtures, the homolytic cleavage of Co−C bonds induced by visible light generates α‐alkene acyl radicals that spontaneously undergo intramolecular radical addition to afford organocobalt‐functionalized cyclic polyesters and CO2‐based polycarbonates with excellent regioselectivity. The cyclic products can either react with radical scavengers to generate metal‐free cyclic polymers or serve as photo‐initiators for organometallic‐mediated radical polymerization (OMRP) to produce tadpole‐shaped copolymers.
Designing of a β‐Cyclodextrin‐based supramolecular fluorescent sensor doped with superparamagnetic α‐Fe2O3 nanoparticles with improved light fastness, thermal, and photoluminescent properties
Authors: Philip Sherin , Kuriakose Sunny , Mathew Tessymol 
Published: May 2021

Abstract1‐Pyrene butyric acid (PBA), a carboxylic derivative of pyrene, which is a well‐studied fluoroprobe, has been greatly used for fluorescent modification of macromolecules belonging to different classes. The present study aimed at the synthesis and characterization of fluorescently modified β‐cyclodextrin (CD) by covalent immobilization of PBA onto supramolecular CD via Steglich esterification. Fluorescently modified CD‐PBA conjugate was further encapsulated with iron (III) oxide nanoparticles (IONP), which belong to the α‐Fe2O3 (hematite) phase. The three systems PBA, CD‐PBA, and CD‐PBA‐IONP were well characterized and compared for their photoresponsive and thermal properties. Photo stability of the samples under study was investigated by exposing the samples to visible light upto 6 h and at regular intervals of time measuring their respective photodegradation by UV/visible spectrophotometry. Thermal properties were monitored using thermogravimetric (TG‐DTG) analysis. Steady state fluorescent studies were performed for the photoluminescent properties. Also, time correlated single photon counting technique was used to measure the fluorescent lifetime of the samples in order to have a better understanding of the quenching mechanism prevailing.
Preparation of poly(butylene succinate) vitrimer with thermal shape stability via transesterification reaction
Authors: Yin Yue , Yang Jian , Meng Linghui 
Published: May 2021

AbstractPoly(butylene succinate) (PBS) refers to a high‐performance biodegradable polymer employed to substitute petroleum polymers that cause environmental issues. However, PBS exhibits the defect of flowing above the melting point and rapid dripping for its poor melt strength. Accordingly, this study proposed a novel method to fabricate PBS vitrimer by exploiting reactive extrusion technology to mix diepoxide with PBS and then by employing zinc acetate as a catalyst to crosslink the PBS. Therefore, after the reaction extrusion blending, the blend still has a lower viscosity and high processing performance; in the subsequent curing process, the polymer undergoes a transesterification reaction and the viscosity increases. Via transesterification to form a cross‐linked network, the storage modulus, and loss modulus of PBS vitrimer at 140°C reach 55,800% and 3500% of pure PBS, respectively. At this time, the crystallinity of PBS vitrimer is still as high as 56.9% (The crystallinity of pure PBS is 47.4%). And the shape stability of PBS at high temperatures was significantly improved. Moreover, PBS vitrimer could still be reshaped after the cross‐linking process. This study proposed a facile method to produce PBS materials exhibiting high thermal shape stability.
Activation of catalytic DNAzyme by binding‐induced DNA displacement for homogeneous assay
Authors: Fan Wei , Chen Junbo , Du Huan , Hu Changjia , Yang Peng , Hou Xiandeng 
Published: May 2021

AbstractThe sensitive assays for protein, especially for the DNA‐based assay, are often dependent on the amplification procedure with assistance of enzyme. Compared with a protein enzyme, deoxyribozyme (DNAzyme) exhibits similar catalytic activity and specificity and better flexibility. In this work, we streamlined the binding induced DNA displacement (BINDD) strategy for the activation of DNAzyme cleavage. Since the intrinsic element of DNAzyme is the nucleic acids, it is easy to join the BINDD by hybridization with an affinity probe. The activity of DNAzyme was initiated by the BINDD reaction mediated by the recognition affinity probe with target proteins. Upon DNAzyme release, it was able to catalyze and cleave the predesigned substrates, generating the enhanced fluorescence signal indicating the protein concentration. Such a constructed homogeneous assay is available and effective in human serum when it was used for detection of platelet derived growth factor‐BB (PDGF‐BB) and prostate specific antigen (PSA), with detection limits of 100 pM and 200 pM, respectively.
Enantioselective Cross‐couplings between Halide Derivatives and Organometallics by Using Iron and Cobalt Catalysts: Formation of C−C Bonds
Authors: Shu Tao , Cossy Janine 
Published: May 2021

AbstractThis review highlights the recent achievements of iron‐ and cobalt‐catalyzed enantioselective cross‐couplings of halide derivatives with organometallic reagents for the construction of C‐C bonds. Synthetic applications of enantioselective cross‐couplings to natural products and biologically active compounds are also covered showing the power of these cross‐couplings in organic synthesis.
Transition‐Metal‐Free Coupling of Polyfluorinated Arenes and Functionalized, Masked Aryl Nucleophiles
Authors: Finck Lucie , Oestreich Martin 
Published: May 2021

AbstractA chemoselective C(sp2)−C(sp2) coupling of sufficiently electron‐deficient fluorinated arenes and functionalized N‐aryl‐N’‐silyldiazenes as masked aryl nucleophiles is reported. The fluoride‐promoted transformation involves the in situ generation of the aryl nucleophile decorated with various sensitive functional groups followed by a stepwise nucleophilic aromatic substitution (SNAr). These reactions typically proceed at room temperature within minutes. This catalytic process allows for the functionalization of both coupling partners, furnishing highly fluorinated biaryls in good yields.
Actuator fault detection for a two‐stage chemical reactor based on the functional observer approach
Authors: Wu Yu , Du Dongsheng , Mao Zehui 
Published: May 2021

AbstractThis paper presents a new method of actuator fault detection based on the functional observer approach for a two‐stage chemical reactor with disturbance, parameter uncertainty, and time‐delay. The mechanism analysis method is used to model the system and the observer is designed. The exogenous disturbance can be decoupled completely from the error dynamic systems by letting some relevant constraints ensure the robustness of the residual generator. Stability conditions are obtained by using the Lyapunov–Krasovskii functional approach in the form of linear matrix inequalities (LMIs). Finally, simulation results are given to illustrate the effectiveness of the proposed method.
Aqueous Conversion of Fructose Phosphate Precursor Nanoparticles into Emissive C‐Dot Composite Nanoparticles
Authors: Sabljo Kristina , Popescu Radian , Michenfelder Nadine C. , Unterreiner Andreas‐Neil , Gerthsen Dagmar , Feldmann Claus 
Published: May 2021

AbstractA one‐pot, fully water‐based synthesis of blue‐ and red‐emitting C‐dots is presented. To this concern, [ZrO]2+[F6P]2− and [Eu(OH)]2+[F6P]2− precursor nanoparticles (F6P: D‐fructose‐6‐phosphate) are prepared in water and converted to C‐dot@[ZrO]2+[HPO4]2− and C‐dot@[Eu(OH)]2+[HPO4]2− composite nanoparticles in boiling water (100 °C) via microwave heating. Composition, structure, and fluorescence of the composite nanoparticles are validated by different analytical methods (e. g., FT‐IR, EA, TG, DLS, SEM, TEM, EDXS). The resulting aqueous suspensions are characterized by high colloidal stability and intense emission. Specifically, C‐dot@[Eu(OH)]2+[HPO4]2− exhibits Eu3+‐type red emission in water. The one‐pot water‐based synthesis with fructose‐containing precursor nanoparticles and the structure of the phosphate‐stabilized C‐dot composite nanoparticles are reported for the first time.
Blockchain‐based framework for secured storage, sharing, and querying of electronic healthcare records
Authors: Kaur Jasleen , Rani Rinkle , Kalra Nidhi 
Published: May 2021

SummaryMedical records contain vital, critical, and confidential information of any person. Paper‐based medical records are being used by many hospitals that suffer from various issues like large physical storage requirements, limited security, and life. Electronic health records (EHRs) can transform this entire system but faces various security threats like unintentional disclosure, tampering, data leaks, lack of security mechanisms, and data access policies. Thus, there arises a need for a decentralized, tamper‐proof, and transparent healthcare network. In this article, a permissioned blockchain‐based framework using Hyperledger Fabric (HLF) is proposed, which provides secure storage, sharing, and querying of EHRs. For better data accessibility and security, algorithms have been designed to define the functionality of patients, doctors, and third‐party administrator using smart‐contracts. In the existing approaches, LevelDB (key store database) is used as a state database that is not suitable for handling complex queries. To overcome this issue, we have used CouchDB (document store database) as a state database where the search is based on keys and data values both rather than only keys. To measure the various performance indicators for this framework, a blockchain benchmark tool “Hyperledger Caliper” is used. The experimental results show the effectiveness and efficiency of the proposed framework.
An approach based on Yet Another Next Generation for software‐defined networking management
Authors: Montoya‐Munoz Ana Isabel , Casas‐Velasco Daniela , Estrada‐Solano Felipe , Caicedo Rendon Oscar Mauricio , Saldanha da Fonseca Nelson L. 
Published: May 2021

SummaryThe lack of a Management Plane specification in the software‐defined networking (SDN) is a fundamental problem for the integrated management of networks that follow this paradigm. Several solutions have addressed this problem, but they do not provide data models intended to support Fault, Configuration, Accounting, Performance, and Security (FCAPS) in SDN from a specialized Management Plane. In this paper, we introduce a technology‐agnostic approach that comprises mainly a collection of YANG data models and their relationships. These models characterize SDN management and handle technology heterogeneity. To evaluate our approach, we developed the proof of concept of the YANG data models in an SDN scenario involving the configuration of devices from different vendors supporting diverse technologies. The evaluation results show the efficiency of our approach regarding response time, composition time, consumption time, and network traffic.
Altered connectivity of the default mode network in cognitively stable adults with Down syndrome: “Accelerated aging” or a prelude to Alzheimer's disease?
Authors: Rosas H. Diana , Lewis Lydia R. , Mercaldo Nathaniel D. , Nasr Shahin , Brickman Adam M. , Siless Viviana , Yassa Michael , Sathishkumar Mithra , Lott Ira , Schupf Nicole , Silverman Wayne , Lai Florence ,   the Alzheimer's Disease in Down Syndrome (ADDS) Consortium
Published: May 2021

AbstractIntroductionMost individuals with Down syndrome (DS) have the neuropathological changes of Alzheimer's disease (AD) by age 40 and will have developed dementia by age 60. Alterations of the intrinsic connectivity of the default mode network (DMN) are associated with AD in the neurotypical population. In this study, we sought to determine whether, and how, connectivity between the hubs of the DMN were altered in cognitively stable adults with DS who did not have evidence of either mild cognitive impairment or AD.MethodsResting state functional MRI scans were collected from 26 healthy adults with DS and 26 healthy age‐matched non‐DS controls. Nodes comprising the DMN were generated as ROI's (regions of interest) and inter‐nodal correlations estimated.ResultsAnalysis of intra‐network connectivity of the DMN revealed anterior‐posterior DMN dissociation and hyper‐ and hypo‐connectivity, suggesting “accelerated aging” in DS.DiscussionDisruption of the DMN may serve as a prelude for AD in DS.
Brain‐gut psychotherapies: Promising tools to address gastrointestinal problems in patients with eating disorders
Authors: Wildes Jennifer E. , Bedell Alyse , Graham Andrea K. , Kells Meredith 
Published: May 2021

AbstractGastrointestinal (GI) problems are common in individuals with eating disorders (EDs) and associated with distress, impairment, and increased healthcare utilization. GI symptoms may be exacerbated by meals and other interventions central to ED recovery thereby contributing to negative clinical outcomes. Informed by models emphasizing the role of the brain‐gut axis in the expression of GI symptoms, this article describes a program of research to adapt “brain‐gut psychotherapies” for EDs. First, the role of the brain‐gut axis in GI symptoms is described, and evidence‐based brain‐gut psychotherapies are reviewed, with an emphasis on cognitive behavioral therapy for GI disorders and gut‐directed hypnotherapy. Next, future directions for research in EDs to (a) understand the impact of GI symptoms on illness course and outcome; (b) clarify target engagement; (c) evaluate brain‐gut psychotherapies; and (d) optimize intervention reach and delivery are described. We present a conceptual model that emphasizes GI‐specific anxiety and altered gut physiology as targets of brain‐gut psychotherapies in EDs, and discuss several issues that need to be addressed in designing clinical trials to test these interventions. We also describe how engagement with multidisciplinary stakeholders and use of digital tools could speed translation from the laboratory to clinical settings.
Body size and tree species composition determine variation in prey consumption in a forest‐inhabiting generalist predator
Authors: van Schrojenstein Lantman Irene M. , Vesterinen Eero J. , Hertzog Lionel R. , Martel An , Verheyen Kris , Lens Luc , Bonte Dries 
Published: May 2021

AbstractTrophic interactions may strongly depend on body size and environmental variation, but this prediction has been seldom tested in nature. Many spiders are generalist predators that use webs to intercept flying prey. The size and mesh of orb webs increases with spider size, allowing a more efficient predation on larger prey. We studied to this extent the orb‐weaving spider Araneus diadematus inhabiting forest fragments differing in edge distance, tree diversity, and tree species. These environmental variables are known to correlate with insect composition, richness, and abundance. We anticipated these forest characteristics to be a principle driver of prey consumption. We additionally hypothesized them to impact spider size at maturity and expect shifts toward larger prey size distributions in larger individuals independently from the environmental context. We quantified spider diet by means of metabarcoding of nearly 1,000 A. diadematus from a total of 53 forest plots. This approach allowed a massive screening of consumption dynamics in nature, though at the cost of identifying the exact prey identity, as well as their abundance and putative intraspecific variation. Our study confirmed A. diadematus as a generalist predator, with more than 300 prey ZOTUs detected in total. At the individual level, we found large spiders to consume fewer different species, but adding larger species to their diet. Tree species composition affected both prey species richness and size in the spider's diet, although tree diversity per se had no influence on the consumed prey. Edges had an indirect effect on the spider diet as spiders closer to the forest edge were larger and therefore consumed larger prey. We conclude that both intraspecific size variation and tree species composition shape the consumed prey of this generalist predator.
Regioselectivity of the Conjugate Addition of Amines to Dissymmetrical Pull‐Pull Alkenes
Authors: Rulev Alexander Yu. , Zubkov Ilya N. , Ushakov Igor A. , Semenov Valentin A. , Vashchenko Alexander V. , Maddaluno Jacques 
Published: May 2021

AbstractThe regioselectivity of the conjugate nucleophilic addition of amines to vicinal di‐acceptor‐substituted alkenes has been studied. A set of results obtained with standard primary and secondary amines gives some clues on the relative acceptor character of classical electron‐withdrawing groups (EWG). We have shown in addition that computed inverse local nucleophilicity index can be used to predict the regioselectivity of the nucleophilic attack.
Extremely Crowded Biaryls
Authors: Du Yuchen , Mague Joel T. , Pascal Robert A. 
Published: May 2021

AbstractHighly congested derivatives of biphenyl were prepared by double Diels‐Alder reactions of cyclopentadienones with substituted butadiynes. The reaction of 2,3,5‐tri(tert‐butyl)cyclopentadienone (5) and diphenylbutadiyne (3) gave only the single adduct, 1‐(phenylethynyl)‐2‐phenyl‐3,5,6‐tri‐tert‐butylbenzene (6), and even extreme conditions gave no second addition. When tetracyclone (4) was added to bis(trimethylsilyl)butadiyne (8), two additions were achieved, but one silyl group was lost either during, or immediately following, the second addition to give 2‐(trimethylsilyl)‐2′,3,3′,4,4′,5,5′,6‐octaphenylbiphenyl (11). However, when 3,4‐diphenyl‐2,5‐dimethylcyclopentadienone (12) was added to 8, the fully substituted 2,2′‐bis(trimethylsilyl)‐4,4′,5,5′‐tetraphenyl‐3,3′,6,6′‐tetramethylbiphenyl (14) was formed. The X‐ray structures of compounds 11 and 14 show them to be quite crowded, but the central biphenyl rings do not exhibit the distortions previously observed in decaphenylbiphenyl. In an alternative approach, arynes were added to 5,5′‐bis(4‐chlorophenyl)‐3,3′,4,4′‐tetraphenyl‐2,2′‐bis(cyclopentadienone) (18). Simple benzyne added twice to give 4,4′‐bis(4‐chlorophenyl)‐2,2′,3,3′‐tetraphenyl‐1,1′‐binaphthyl (19) in low yield, but tetraphenylbenzyne, generated from tetraphenylanthranilic acid, added only once.
Residual dune ridges: Sedimentary architecture, genesis, and implications for palaeo‐climate reconstructions
Authors: Lindhorst Sebastian , Reimann Tony 
Published: May 2021

AbstractSedimentary architecture and genesis of residual dune ridges in a temperate climate are presented and implications for their use as archive of changes in long‐term precipitation and wind climate are discussed. Residual dunes are common features of wet aeolian systems, where they form sets of shallow ridges, oriented perpendicular to the prevailing wind direction. Residual dune ridges of the study area are vegetated and typically elevate 0.6 to 2.5 m above the surrounding interdune flats. They develop on the lower stoss side of active transgressive dunes, triggered by periods of elevated groundwater table and hence colonization of the foot of the dune by rapid growing pioneer vegetation. Stabilized by plants, the growing ridge detaches from the active transgressive dune and gets abandoned within years in the course of the downwind‐migration of the transgressive dune. Grain‐size data suggest a main sediment supply from the transgressive dune and only minor input from other sources. Ground‐penetrating radar reveals that the residual dune ridges are composed of windward‐dipping as well as leeward‐dipping sedimentary beds. Leeward‐dipping strata reflect sediment supply from the parental dune, whereas windward‐dipping beds are seen to result from sediment redistribution along the ridge and sediment supply from the adjacent swales during the ridge growth period. Multi‐annual to multi‐decadal variability in precipitation leads to the development of sequences composed of tens of ridges, spanning time periods of several centuries. Spacing of individual ridges in these sequences is controlled not by long‐term variability in precipitation alone, but probably also reflects variable wind intensity which affects the migration rate of the parental dune. The important role of vegetation in ridge construction makes these landforms a demonstrative example of landscape development by geo‐biosphere interacting processes.
The pricing mechanism between ETF option and spot markets in China
Authors: Dong Da , Liu Qingfu , Tao Pingping , Ying Zhiliang 
Published: May 2021

AbstractThis paper investigates the price discovery and volatility spillover effects between the exchange‐traded fund (ETF) option and spot markets in China. Employing a sample of China Securities Index (CSI) 300 ETF options and spots, we find that the CSI 300 ETF options interact with the spot markets, with the CSI 300 ETF options contributing more than the spots in terms of pricing efficiency, especially on the Shanghai Stock Exchange (SSE). We further find that the option markets on the SSE can dominate the option markets on the Shenzhen Stock Exchange, revealing investors' trading behaviors across different markets.
Specification analysis of VXX option pricing models under Lévy processes
Authors: Cao Jiling , Ruan Xinfeng , Su Shu , Zhang Wenjun 
Published: May 2021

AbstractWe conduct a comprehensive study on the specifications of VXX option pricing models under Lévy processes during the period from 2010 to 2017 based on in‐sample and out‐of‐sample performance tests. Our empirical results imply that a jump component plays an important role in VXX option pricing. In particular, we find that infinite‐activity jump models are superior to finite‐activity jump models. More importantly, this paper corrects the VXX option pricing theory in the literature; that is the discounted VXX price should be a martingale under the risk‐neutral measure as the VXX is an exchange‐traded debt security.