bluuebunny/crossref_metadata_2025_split huggingface dataset:
Controlled Synthesis, Chiral Assembly, and Circularly Polarized Luminescence of Poly(Phenyl Isocyanide)‐Block‐Polyfluorene Copolymers
Authors: Zou Hui , Han Shan‐Shan , Li Guo‐Qiang , Zhou Li , Liu Na , Wu Zong‐Quan 
Published: May 2023

AbstractIn this work, π‐conjugated block copolymers consisting of poly(phenyl isocyanide) (PPI) and polyfluorene (PF) segments are facilely prepared by one‐pot sequential polymerization of phenyl isocyanide (monomer 1) and 7‐bromo‐9,9‐dioctylfluorene‐2‐boronic acid pinacol ester (monomer 2). The Pd(II)‐terminated PPI is first prepared via polymerizing monomer 1 catalyzed with phenyl alkyne‐Pd(II) complex and then utilized to initiate the controlled Suzuki cross‐coupling polymerization of monomer 2, yielding various PPI‐b‐PF copolymers possessing controlled molar mass and narrow dispersity. Owing to the helical conformation of PPI segment and π‐conjugated structure of PF segment, PPI‐b‐PF copolymers present distinctive optical property and fascinating chiral self‐assembly behavior. During the self‐assembly process, chirality transfer from helical PPI block to the supramolecular aggregates of helical nanofibers occurs to afford optically active helical nanofibers with high optical activity. Furthermore, the self‐assembled helical nanofibers exhibit excellent circularly polarized luminescence performance.
A field map updating algorithm to improve fat‐water spiral imaging
Authors: Chao Tzu Cheng , Wang Dinghui , Krishnamoorthy Guruprasad , Pipe James G. 
Published: May 2023

PurposeAn accurate field map is essential to separate fat and water signals in a dual‐echo chemical shift encoded spiral MRI scan. A rapid low‐resolution B0 map prescan is usually performed before each exam. Occasional inaccuracy in these field map estimates can lead to misclassification of the water and fat signals as well as blurring artifacts in the reconstruction. The present work proposes a self‐consistent model to evaluate residual field offsets according to the image data to improve the reconstruction quality and facilitate the scan efficiency.Theory and MethodsThe proposed method compares the phase differences of the two‐echo data after correcting for fat frequency offsets. A more accurate field map is approximated according to the phase discrepancies and improved image quality. Experiments were conducted with simulated off‐resonance on a numerical phantom, five volunteer head scans, and four volunteer abdominal scans for validation.ResultsThe initial reconstruction of the demonstrated examples exhibit blurring artifacts and misregistration of fat and water because of the inaccuracy of the field map. The proposed method updates the field map to amend the fat and water estimation and improve image quality.ConclusionsThis work presents a model to improve the quality of fat‐water imaging of the spiral MRI by estimating a better field map from the acquired data. It allows reducing the field map pre‐scans before each spiral scan under normal circumstances to increase scan efficiency.
Bachelor of nursing students' experiences of a longitudinal team training intervention and the use of teamwork skills in clinical practice—A qualitative descriptive study
Authors: Karlsen Tore , Hall‐Lord Marie Louise , Wangensteen Sigrid , Ballangrud Randi 
Published: May 2023

AbstractAimsTo describe nursing students' experiences of a TeamSTEPPS® longitudinal team training program and the application of teamwork skills in clinical practice.DesignA descriptive qualitative design.MethodsOverall, 22 nursing students participated in six online focus group interviews after attending a TeamSTEPPS® team training program from their first semester. The data were audio‐recorded, transcribed and analysed using inductive content analysis and reported following the COREQ guidelines. The focus group interviews took place in the students' fifth's semester.ResultsThe main category “Learning teamwork is not an event; it's a journey” emerged from 3 generic categories and 12 subcategories. The participants reported that grasping the relevance of team training and the use of teamwork skills takes time. Utilizing these skills improved their awareness of being a team member and facilitated learning.ConclusionTeam training raised the participants' awareness of teamwork as an essential component of being a professional nurse. Additionally, understanding the complexity of teamwork takes time.
Preparation of CO2‐based poly(carbonate‐co‐lactide) with different porphyrin aluminum (III) catalysts
Authors: Li Tao , Liu Zhijian , Chen Yao , Sun Na , Shu Haozhou , Wu Lili , Zhang Chaocan , Xie Dong 
Published: May 2023

AbstractTwo‐component catalysts composed of tetra (para‐X substituted) phenylporphyrin aluminum (III) chloride, T (p‐X‐P)PAlCl, (where X = H, F, Cl, Br, CH3, OCH3, tert‐butyl), and cocatalyst bis(triphenylphosphine)imminium chloride (PPN+Cl−), could initiate the polymerization of propylene oxide (PO). And they could react with rac‐lactide, (rac‐LA), in the presence of propylene oxide (PO), to yield chains of enriched isotactic polylactide (PLA) with trace polyether segment. Also, these catalysts displayed different catalytic activity in the copolymerization of CO2 and PO, resulting in poly(carbonate‐co‐ether) copolymer with different carbonate unit content (CU%). Further, these catalysts could initiate one‐pot regio‐ and stereo‐ selective terpolymerization of rac‐LA, CO2 and rac‐PO, resulting in multi‐blocky poly(carbonate‐co‐lactide) with trace polyether segment. The structure of the products was verified by 1H NMR, 13C NMR, GPC, and DSC analysis, and it was found that variation of substitution groups in the periphery of porphyrin ligand would affect on the catalytic efficiency of ter‐polymerization, and the relative polymerization reaction ratio of the ring‐opening polymerization of LA (ROP) to the ring‐opening copolymerization of PO and CO2 (ROCOP), resulting in ter‐polymer with different contents of PLA segment and PPC segment. However, H‐T% in polycarbonate unit and Pi% in polylactide unit did not vary much with the change of catalysts.
Miniature mass spectrometer signal processing based on ensemble empirical mode decomposition feature enhancement
Authors: Li Ming , Zhan Chenrui , Lv Yueguang , Chen Jiwen , Wang Yutian , Lu Sixian , Wan Yingqi , Ma Qiang 
Published: May 2023

RationaleThe high sensitivity of the miniature mass spectrometer plays an irreplaceable role in rapid on‐site detection. However, its analysis accuracy and stability should be improved due to the influence of sample pretreatment and use environment. The present study investigates the processing effects of ensemble empirical mode decomposition (EEMD) feature enhancement methods on the determination coefficient (R2) and relative standard deviation (RSD) of caffeine mass spectrometry (MS) signals.MethodsThis paper employs the EEMD method combined with polynomial curve fitting to enhance the characteristics of seven caffeine mass spectrum signals with different concentrations and 15 groups of caffeine mass spectrum signals with the same concentration, and the wavelet analysis method was used for comparative verification. The determination coefficient and RSD of the two methods were compared.ResultsWe found the EEMD method's capability in adaptively decomposing caffeine mass spectrum signals is better than wavelet analysis method. The determination coefficient of the EEMD enhanced feature is better than 0.999, and the RSD is better than 2%, and both are better than wavelet analysis methods.ConclusionsThe feature enhancement processing using the EEMD method has significantly improved the determination coefficient and RSD of the sample curve, improving the accuracy and stability of the data and providing a new way for miniature mass spectrometer signal processing.
Triangular formation control with mixed distance and bearing measurements under limited field of view constraints
Authors: Zhao Xinyue , Yang Qingkai , Pan Yunlong , Fang Hao 
Published: May 2023

AbstractThis article addresses the problem of triangular formation control for a three‐agent group with different measuring capabilities: agent 1 can measure local bearings but with limited field of view (FOV), and agents 2 and 3 can only obtain distance measurements. For agent 1, an orientation controller is first designed to steer its heading to the expected direction. Furthermore, a type of switching control law utilizing pure bearing measurements is proposed to reach the desired angle with respect to the other two agents. Concurrently, it is guaranteed that the flip ambiguity of the formation can be excluded. For agents 2 and 3, the extended distance‐based control algorithm is proposed by invoking the so‐called signed area strategy to determine their actuation. With this control scheme, it is proven that the triangular formation is stabilized globally even in the presence of FOV constraints. The effectiveness is validated through numerical simulations and physical experiments on three nano quadrotors.
Crude Polysaccharide Produces Silver Nanoparticles with Inherent Antioxidant and Antibacterial Activity
Authors: Sana Siva Sankar , Hou Tianyu , Li Huizhen , Vadde Ramakrishna , Basavegowda Nagaraj , Chakravorty Arghya , Kumbhakar Divya Vishambhar , Zhang Zhijun , Mamidi Narsimha 
Published: May 2023

AbstractWe present an efficient and biologically based process for producing silver nanoparticles (Ag‐NPs) using crude polysaccharides extracted from Perilla frutiscences plants (PFCPS). The PFCPS serves as both a reducing agent and a capping agent during Ag‐NP formation. Characterization of the synthesized Ag‐NPs was performed through various techniques such as Ultraviolet‐Visible (UV‐Vis) absorption spectroscopy, X‐ray diffraction (X‐RD), Fourier transform infrared spectroscopy (FT‐IR), and high‐resolution transmission electron microscopy (HR‐TEM). Antioxidant properties of the Ag‐NPs were evaluated using DPPH, reducing power, and ABTS free radical assays, revealing their potential use as antioxidants. Additionally, Ag‐NPs displayed promising antibacterial activity against Escherichia coli and Klebsiella pneumonia, suggesting their potential for application in medical and healthcare products for the prevention and treatment of infections.
Design, Synthesis, and Molecular Modeling of New and Safe Azole Oxime Esters with Promising Antifungal Activity
Authors: Yurtoğlu Sibel , Sari Suat , Kart Didem , Sabuncuoğlu Suna , Saraç Selma 
Published: May 2023

AbstractFungal infections have become a major public health issue with dramatically increasing morbidity, mortality and cost of hospitalization. Azole antifungals are first‐in‐line medications against most types of mycoses and azoles having an oxime moiety, although not extensively investigated, were reported to have great antifungal potential, as well as, activity against Gram‐positive bacteria. In the current study, a new series of 2‐(1H‐imidazol‐1‐yl)‐1‐phenylethanone oxime esters (5 a–l) were synthesized and tested for their antimicrobial activities. The sorbic acid ester (5 c) was found to be highly promising against Candida albicans and Candida parapsilosis (MIC=4 μg/ml). In addition, 5 c was not toxic to the healthy murine fibroblast. Molecular modelling suggested that the compounds were druglike, orally available, not substrates of efflux pumps, and probably acted through fungal CYP51 inhibition, which is the major action mechanism of azole antifungals.
Highly Dispersed Pt‐Au/rGO Catalysts Prepared by Hyperbranched Polyglycerols for Efficient Electrooxidation of Methanol
Authors: Ren Guohong , Chen Yuting , Liu Chunyu , Zhang Shenhang , Li Haotian , Chen Hong , Dong Xingzheng , Chu Ruixia , Qiu Fangyuan , Liu Zhongsu 
Published: May 2023

AbstractRecently, fuel cells especially direct methanol fuel cells (DMFCs), have attracted great interest because of their high energy density, their pollution‐free operation mode and thus their prospect for use in convenient transportation. Although platinum (Pt) catalyst is an efficient catalysts for DMFCs, it has some problems such as high price, poor stability and durability. Therefore, the research of high performance Pt catalysts becomes the focus. Firstly, the hyperbranched polyglycerols (HPG) were synthesized by the one‐step anionic ring‐opening polymerization. The Pt‐Au bimetallic catalysts supported on reduced graphene oxide (Pt‐Au‐HPG/rGO) were synthesized via a hydrothermal method, using HPG as the template and stabilizer. The electrocatalytic performances for the electrooxidation of methanol were investigated by electrochemical methods. Compared with commercial Pt/C (10 wt %) catalysts, Pt‐Au‐HPG/rGO has the larger electrochemically active surface area (ECSA, 108.8 m2 g−1), higher catalytic performance (0.498 A mgmetal−1) and better stability. This excellent performance is attributed to the good dispersion and conductivity of Pt‐Au‐HPG/rGO for the addition of HPG, rGO and Au. Meanwhile, the bifunctional and electronic effects between Au and Pt improved the electrochemical performance of the samples.
Synthesis of Chiral Tricyclic Pyrone Molecules via Palladium(0)‐Catalyzed Displacement Reactions of Chiral Tricyclic Pyrone Acetate With Azide or Amine
Authors: Morita Shunya , Ren Zhaoyang , Fan Huafang , Hua Duy H. 
Published: May 2023

AbstractTricyclic pyrone (TP) molecules have shown protection of MC65 neuroblastoma cells death induced by amyloid‐β proteins through SβC gene, a decrease of amyloid‐β peptide levels, and improvement of motor functions and memory in Alzheimer's disease mouse and rat models. Mechanistic studies suggest TP molecules modulate N‐methyl‐D‐aspartate receptor. A short synthesis of chiral TP analogs was sought using a Pd(0)‐catalyzed displacement of TP allylic acetate intermediate with sodium azide or substituted benzylamines. A three‐step sequence of reactions by the treatment of 2‐{(5aS,7S)‐3‐methyl‐1‐oxo‐1,5a,6,7,8,9‐hexahydropyrano[4,3‐b]chromen‐7‐yl}allyl acetate (9) with (Ph3P)4Pd and sodium azide, followed by reduction with Zn‐NH4OCHO and coupling with 3‐fluoro‐4‐hydroxybenzaldehyde and NaCNBH3 was found to give TP coupling molecule, (5aS,7S)‐7‐(1‐(3‐fluoro‐4‐hydroxybenzylamino)prop‐2‐en‐2‐yl)‐3‐methyl‐6,7,8,9‐tetrahydropyrano[4,3‐b]chromen‐1(5aH)‐one (2), in a good yield. An alternative shorter pathway – a two‐step sequence of reactions – by the displacement of 9 by 4‐(t‐butyldimethylsilyloxy)‐3‐fluoro‐benzylamine with a catalytic amount of (Ph3P)4Pd in THF followed by removal of the silyl ether protecting group gave 2, albeit in a lower chemical yield. The described syntheses should provide general procedures for the synthesis of a library of TP molecules for the discovery of anti‐Alzheimer drugs.
Quantum chemical modeling of organic enhanced atmospheric nucleation: A critical review
Authors: Elm Jonas , Ayoubi Daniel , Engsvang Morten , Jensen Andreas Buchgraitz , Knattrup Yosef , Kubečka Jakub , Bready Conor J. , Fowler Vance R. , Harold Shannon E. , Longsworth Olivia M. , Shields George C. 
Published: May 2023

AbstractAerosol particles are important for our global climate, but the mechanisms and especially the relative importance of various vapors for new particles formation (NPF) remain uncertain. Quantum chemical (QC) studies on organic enhanced nucleation has for the past couple of decades attracted immense attention, but very little remains known about the exact organic compounds that potentially are important for NPF. Here we comprehensively review the QC literature on atmospheric cluster formation involving organic compounds. We outline the potential cluster systems that should be further investigated. Cluster formation involving complex multi‐functional organic accretion products warrant further investigations, but such systems are out of reach with currently applied methodologies. We suggest a “cluster of functional groups” approach to address this issue, which will allow for the identification of the potential structure of organic compounds that are involved in atmospheric NPF.This article is categorized under:
Theoretical and Physical Chemistry > Reaction Dynamics and Kinetics
Software > Quantum Chemistry
Theoretical and Physical Chemistry > Thermochemistry
Molecular and Statistical Mechanics > Molecular Interactions
Hilbert series and higher-order Lagrangians for the O(N) model
Authors: Bijnens Johan , Gudnason Sven Bjarke , Yu Jiahui , Zhang Tiantian 
Published: May 2023

Abstract
We compare the Hilbert series approach with explicit constructions of higher-order Lagrangians for the O(N) nonlinear sigma model. We use the Hilbert series to find the number and type of operators up to mass dimension 16, for spacetime dimension D up to 12 and N up to 12, and further classify the operators into spacetime parity and parity of the internal symmetry group O(N). The explicit construction of operators is done up to mass dimension 12 for both parities even and dimension 10 for the other three cases. The results of the two methods are in full agreement. This provides evidence for the Hilbert series conjecture regarding co-closed but not co-exact k-forms, which takes into account the integration-by-parts relations.
What is the link between temperature, carbon dioxide and methane? A multivariate Granger causality analysis based on ice core data from Dome C in Antarctica
Authors: Larsson Rolf , Persson Erik K. 
Published: May 2023

AbstractThis paper continues the work of Kang and Larsson Theoretical and Applied Climatology 116:537–548 (2014) What is the link between temperature and carbon dioxide levels? A Granger causality analysis based on ice core data. Theoretical and Applied Climatology 116:537-548, by adding methane to the study of causality between temperature and carbon dioxide. The data used goes 800,000 years back in time which is possible due to it being extracted from ice cores located at Dome C in Antarctica. First we use linear interpolation to make the three data sets equidistant to be able to employ statistical methods. We adjust for a deterministic trend and find the best model fit to be an autoregressive model with lag two and a piecewise quadratic trend. By employing multivariate Granger causality tests we find strong evidence that temperature, carbon dioxide and methane all Granger cause each other in both directions i.e. carbon dioxide Granger causes temperature and temperature Granger causes carbon dioxide, etc. This is in accordance with the findings of Kang and Larsson, with the extension that we can add methane to establish a trivariate feedback system between temperature, carbon dioxide and methane.
Tracking social provenance in chains of retweets
Authors: Migliorini Sara , Gambini Mauro , Quintarelli Elisa , Belussi Alberto 
Published: May 2023

AbstractIn the era of massive sharing of information, the term social provenance is used to denote the ownership, source or origin of a piece of information which has been propagated through social media. Tracking the provenance of information is becoming increasingly important as social platforms acquire more relevance as source of news. In this scenario, Twitter is considered one of the most important social networks for information sharing and dissemination which can be accelerated through the use of retweets and quotes. However, the Twitter API does not provide a complete tracking of the retweet chains, since only the connection between a retweet and the original post is stored, while all the intermediate connections are lost. This can limit the ability to track the diffusion of information as well as the estimation of the importance of specific users, who can rapidly become influencers, in the news dissemination. This paper proposes an innovative approach for rebuilding the possible chains of retweets and also providing an estimation of the contributions given by each user in the information spread. For this purpose, we define the concept of Provenance Constraint Network and a modified version of the Path Consistency Algorithm. An application of the proposed technique to a real-world dataset is presented at the end of the paper.
A machine learning-based optimization approach for pre-copy live virtual machine migration
Authors: Haris Raseena M. , Khan Khaled M. , Nhlabatsi Armstrong , Barhamgi Mahmoud 
Published: May 2023

AbstractOrganizations widely use cloud computing to outsource their computing needs. One crucial issue of cloud computing is that services must be available to clients at all times. However, the cloud services may be temporarily unavailable due to maintenance of the cloud infrastructure, load balancing of services, defense against cyber attacks, power management, proactive fault tolerance, or resource usage. The unavailability of cloud services impacts negatively on the business model of cloud providers. One solution to tackle the service unavailability is Live Virtual Machine Migration (LVM), that is, moving virtual machines (VMs) from the source host machine to the destination host without disrupting the running application. Pre-copy memory migration is a common LVM approach used in most networked systems such as the cloud. The main difficulty with this approach is the high rate of frequently updating memory pages, referred to as "dirty pages. Transferring these updated or dirty pages during the pre-copy migration approach prolongs the total migration time. After a predefined iteration, the pre-copy approach enters the stop-and-copy phase and transfers the remaining memory pages. If the remaining pages are huge, the downtime or service unavailability will be very high -resulting in a negative impact on the availability of the running services. To minimize such service downtime, it is critical to find an optimal time to migrate a virtual machine in the pre-copy approach. To address the issue, this paper proposes a machine learning-based method to optimize pre-copy migration. It has mainly three stages (i) Feature selection (ii) Model generation and (iii) Application of the proposed model in pre-copy migration. The experiment results show that our proposed model outperforms other machine learning models in terms of prediction accuracy and it significantly reduces downtime or service unavailability during the migration process.
“The rich will always be able to dispose of their waste”: a view from the frontlines of municipal failure in Makhanda, South Africa
Authors: Kalina Marc , Makwetu Ncebakazi , Tilley Elizabeth 
Published: May 2023

AbstractA significant proportion of South African municipalities, who hold the mandate for providing solid waste management (SWM) services for millions of South Africans, appear to be on the brink of collapse. On the frontlines of municipal failure, the city of Makhanda, following two decades of poor governance and mismanagement, has found itself unable to fulfil its mandate, with the state retreating on SWM service provision, and disruptions to waste management services becoming a daily reality. Drawing on embedded, qualitative fieldwork, this article examines how differently placed residents have experienced disruptions to SWM services. This work explores how residents of Makhanda’s two halves: the affluent and predominantly white neighbourhoods in the west, and the poor, non-white townships in the east, have (or have not) adapted to manage and dispose of their own waste during periods of disruption. Findings suggest that disruptions to waste management service provision have been broadly experienced by residents. However, the consequences of interruptions to municipal collection have not been evenly borne, as more resourced, western residents have been more successful at managing their own waste disposal, while the residents of Makhanda’s townships are less capable of coping, with affected communities coming to resemble a dumping ground, and residents having to adopt unsafe or environmentally harmful disposal practices. These findings are important because they shed light on the challenges of creating cleaner, more equal communities without healthy municipal participation in waste management services, while raising important considerations for a South Africa facing the possibility of widespread municipal collapse.