bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic Circularly Polarized Luminescence in the Photoexcited States of Racemic [n]Helicenes (n=3–5,7) in Tetrahydrofuran and Dimethyl Sulfoxide Solutions
Authors: Toda Hayato , Otake Shuhei , Ito Akari , Miyasaka Makoto , Fujiki Michiya , Imai Yoshitane 
Published: July 2021

AbstractThis paper reports the first magnetic circularly polarized luminescence (MCPL) characteristics of racemic helicenes, including four unsubstituted [n]helicenes (n=3,4,5,7) and two [4]helicene derivatives bearing methoxy substituents, in tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO) solutions. The value of |gMCPL| was calculated to be of the order of 10−3 T−1 within 350–430 nm under the north‐up (N‐up) and south‐up (S‐up) Faraday geometries in an external magnetic field of 1.6 T. The [n]‐dependent MCPL signs were altered by the N‐up and S‐up geometries.
Role of FTFSI Anion Asymmetry on Physical Properties of AFTFSI (A=Li, Na and K) Based Electrolytes and Consequences on Supercapacitor Application
Authors: Chidiac Joseph , Timperman Laure , Anouti Mérièm 
Published: July 2021

AbstractThis study compares the physicochemical properties of six electrolytes comprising of three salts: LiFTFSI, NaFTFSI and KFTFSI in two solvent mixtures, the binary (3EC/7EMC) and the ternary (EC/PC/3DMC). The transport properties (conductivity, viscosity) as a function of temperature and concentration were modeled using the extended Jones‐Dole‐Kaminsky equation, the Arrhenius model, and the Eyring theory of transition state for activated complexes. Results are discussed in terms of ionicity, solvation shell, and cross‐interactions between electrolyte components. The application of the six formulated electrolytes in symmetrical activated carbon (AC)//AC supercapacitors (SCs) was characterized by cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), electrochemical impedance spectroscopy (EIS) and accelerated aging. Results revealed that the geometrical flexibility of the FTFSI anion allows it to access and diffuse easily in AC whereas its counter ions (Li+, Na+ or K+) can remain trapped in porosity. However, this drawback was partially resolved by mixing LiFTFSI and KFTFSI salts in the electrolyte.
New‐Generation Ligand Design for the Gold‐Catalyzed Asymmetric Activation of Alkynes
Authors: Zuccarello Giuseppe , Escofet Imma , Caniparoli Ulysse , Echavarren Antonio M. 
Published: July 2021

AbstractGold(I) catalysts are ideal for the activation of alkynes under very mild conditions. However, unlike allenes or alkenes, the triple bond of alkynes cannot be prochiral. In addition, the linear coordination displayed by gold(I) complexes places the chiral ligand far away from the substrate resulting in an inefficient transfer of chiral information. This poses a significant challenge for the achievement of high enantiocontrol in gold(I)‐catalyzed reactions of alkynes. Although considerable progress on enantioselective gold(I)‐catalyzed transformations has recently been achieved, the asymmetric activation of non‐prochiral alkyne‐containing small molecules still represents a great challenge. Herein we summarize recent advances in intra‐ and intermolecular enantioselective gold(I)‐catalyzed reactions involving alkynes, discussing new chiral ligand designs that lie at the basis of these developments. We also focus on the mode of action of these catalysts, their possible limitations towards a next‐generation of more efficient ligand designs. Finally, square planar chiral gold(III) complexes, which offer an alternative to chiral gold(I) complexes, are also discussed.
A Spiro‐Containing 7‐Hydroxy‐Carbocoumarin: Facile Two‐Step Synthesis and Enhanced Long‐Wavelength Fluorescence Properties
Authors: Tan Bojun , Ren Jiatong , Chen Shaoli , Ge Zhongxue , Lu Xianming , Yang Xiong , Liu Ning 
Published: July 2021

AbstractIn contrast to the behavior of oxycoumarins, carbocoumarins can exhibit a maximum absorption wavelength which is more red‐shifted into the visible region. However, the fluorescence quantum yield decreases at the same time, restricting their further applications as long‐wavelength fluorophores. Herein, we developed a facile two‐step approach containing [4+1] spiroannulation and deprotection to simply and efficiently synthesize a novel spiro‐containing 7‐hydroxy‐carbocoumarin. Remarkably, with the aid of the rigid spiro structure, the spectral properties of our compound are comprehensively improved compared with previously reported carbocoumarins. The absorption and emission wavelengths show a further red‐shift, and the fluorescence quantum yield also increases significantly by 43 %. Our research not only enriches the database of carbocoumarins with a rapid and convenient synthetic strategy, but also sheds light on the rational design of carbocoumarins with superior spectral properties.
Dynamics of resonant self‐focusing on second harmonic generation of Gaussian laser beam in a rippled density plasma
Authors: Pathak Nidhi , Agarwal Prakash Chandra , Gill Tarsem S. , Kaur Sukhdeep 
Published: July 2021

AbstractResonant second harmonic generation by a Gaussian laser beam in a rippled density plasma is studied using the moment theory approach. The nonlinearity arises through the relativistic mass effect and ponderomotive forces. The laser beam creates a plasma channel and gives rise to electron density perturbation at the laser frequency. The density perturbation beats with electron quiver velocity to produce second harmonics. The ripple provides phase matching and makes the process a resonant one. The second harmonic power efficiency is increased effectively with density ripple. Self‐focusing causes enhancement in the efficiency of harmonic generation.
Kinetic approach on the DIA wave propagation in a non‐extensive distributed dusty plasma
Authors: Abbaszadeh Tohid , Zahed Hossein 
Published: July 2021

AbstractThe Landau damping of the dust ion‐acoustic wave (DIAW) in a dusty plasma with non‐extensive distributed components is analysed relying on the kinetic approach. The electron, ion, and dust particles are effectively modelled by the non‐extensive distribution function of the Tsallis statistics. For a collisionless plasma with different values of plasma components indices, the general dispersion relation is achieved, and the non‐extensivity effects on the frequency, as well as the Landau damping of the DIAW, are studied. We show that for , the preliminary results of the Maxwellian plasma are obtained. The decrease of wave damping is achieved by increasing the coefficient q index and the ion‐to‐electron density ratio. The damping rate also increases with an increasing ion‐to‐electron temperature ratio.
Computationally derived anatomic subtypes of behavioral variant frontotemporal dementia show temporal stability and divergent patterns of longitudinal atrophy
Authors: Ranasinghe Kamalini G. , Toller Gianina , Cobigo Yann , Chiang Kevin , Callahan Patrick , Eliazer Caleb , Kramer Joel H. , Rosen Howard J. , Miller Bruce L. , Rankin Katherine P. 
Published: July 2021

AbstractIntroductionBehavioral variant frontotemporal dementia (bvFTD) can be computationally divided into four distinct anatomic subtypes based on patterns of frontotemporal and subcortical atrophy. To more precisely predict disease trajectories of individual patients, the temporal stability of each subtype must be characterized.MethodsWe investigated the longitudinal stability of the four previously identified anatomic subtypes in 72 bvFTD patients. We also applied a voxel‐wise mixed effects model to examine subtype differences in atrophy patterns across multiple timepoints.ResultsOur results demonstrate the stability of the anatomic subtypes at baseline and over time. While they had common salience network atrophy, each subtype showed distinctive baseline and longitudinal atrophy patterns.DiscussionRecognizing these anatomically heterogeneous subtypes and their different patterns of atrophy progression in early bvFTD will improve disease course prediction in individual patients. Longitudinal volumetric predictions based on these anatomic subtypes may be used as a more accurate endpoint in treatment trials.
A New Approach for the Voltammetric Determination of Amoxicillin in the Dosage Form Using Azo Coupling Reaction with Sulphanilamide
Authors: Kostiv O. , Rydchuk P. , Korkuna O. , Khavchuk M. 
Published: July 2021

AbstractThe novel method of amoxicillin (AM) determination has been developed using single‐sweep polarography. The proposed method is based on the obtaining of yellow coloured azo compound due to azo coupling reaction of previous diazotized sulphanilamide (SA) (in the medium of 0.6 M hydrochloric acid) with amoxicillin at pH=9.0 with the further reduction of the formed analytical form on a dropping mercury electrode. Voltammetric determination of amoxicillin is carried out due to the reduction peak of azo group of the obtained azo compound in the presence of 0.05 mol ⋅ L−1 Na2B4O7 as a background electrolyte at the potential Ecp2=−0.55 V and potential sweep rate of 2.5 V ⋅ s−1. The developed voltammetric method has two linear ranges of the determined concentrations (0.05–2.0) ⋅ 10−5 mol ⋅ L−1 and (0.2–1.0) ⋅ 10−4 mol ⋅ L−1 and the high sensitivity: LOD without the removing of unreacted sodium nitrite is 1.1 ⋅ 10−6 mol ⋅ L−1, and 7.2 ⋅ 10−7 mol ⋅ L−1, when NaNO2 excess is removed using urea. The developed voltammetric technique of AM determination has been approved during the analyses of tablets and oral suspension.
Coupling effects of fuel reforming process and fuel utilization on the system performance of a natural gas solid oxide fuel cell/gas turbine hybrid system
Authors: Chen Hao , Yang Chen , Zhang Biao , Zhou Nana , Harun Nor Farida , Oryshchyn Danylo , Tucker David 
Published: July 2021

SummaryA design study was undertaken of a 100 kW natural gas solid oxide fuel cell (SOFC)/gas turbine (GT) hybrid system to evaluate the impacts of the reforming process under a broad range of SOFC fuel utilizations. An equilibrium reformer model and a one‐dimensional SOFC model are employed to perform system study for this hybrid, while balance of plant model is built in Ebsion to simulate the associated performance of GT cycle. Fifty design cases with varied external fuel reforming temperatures are analyzed based on different SOFC fuel utilization levels. With the decrease of reforming temperature, optimal fuel utilization in terms of efficiency shift from 90% with external reforming to 60% with internal reforming. Highest efficiency up to 74% was achieved with internal reforming, but this came with 1275 K cathode inlet air temperature and 1673 K turbine inlet temperature, which no current fuel cell and few GTs can tolerate. High fuel pre‐reforming rates provided a higher design flexibility and showed opportunities of efficiency improvement with appropriate thermal integration strategy. And the feasibility of achieving high efficiencies in the hybrid system with thermally integrated external reforming will be explored in our future work.Novelty StatementBoth fuel reforming process and fuel utilization could affect the heat and energy balance in the hybrid gas solid oxide fuel cell (SOFC)‐gas turbine (GT) system. However, the optimal design condition considering different fuel reforming approaches and SOFC fuel utilization levels was not determined in the literature. In addition, appropriate integration strategies, used to balance the heat and power between the two subsystems (SOFC and GT), are imperative under different fuel reforming approaches and SOFC fuel utilization levels. But, the feasibility of those thermal integration strategies has not been examined in existing studies. This work studied the coupling effects of SOFC fuel utilization and fuel reforming process on system performance of a natural gas hybrid SOFC/GT cycle. Highest efficiency up to 74% was achieved with internal reforming, but this came with 1275 K cathode inlet air temperature and 1673 K turbine inlet temperature, which no current fuel cell and few GTs can tolerate. High fuel pre‐reforming rates provided a higher design flexibility and showed opportunities of efficiency improvement with appropriate thermal integration strategy.
Post‐fire management effects on sediment (dis)connectivity in Mediterranean forest ecosystems: Channel and catchment response
Authors: González‐Romero Javier , López‐Vicente Manuel , Gómez‐Sánchez Elena , Peña‐Molina Esther , Galletero Pablo , Plaza‐Alvarez Pedro , Moya Daniel , De las Heras Jorge , Lucas‐Borja Manuel Esteban 
Published: July 2021

AbstractForest fires and post‐fire practices influence sediment connectivity (SC). In this study, we use the ‘aggregated index of connectivity’ (AIC) to assess SC in five Mediterranean catchments (198–1090 ha) affected by a wildfire in 2012 in south‐eastern Spain. Two temporal scenarios were considered, immediately after the fire and before post‐fire management, and 2 years after the fire including all practices (hillslope barriers, check‐dams, afforestation, salvage logging and skid trails). One LiDAR (light detection and ranging)‐derived digital elevation model (DEM, 2 m × 2 m resolution) was generated, per scenario. The five catchment outlets were established as the computation target (AICOUT), and structural and functional SC were calculated. Index outputs were normalized to make the results of the non‐nested catchments comparable (AICN‐OUT). The output analysis includes the SC distribution along the catchments and at local scale (929 sub‐catchments, 677 in the burned area), the hillslope and channel measures' effect on SC, and a sedimentological analysis using observed area‐specific sediment yield (SSY) at 10 new (built after post‐fire practices) concrete check‐dams located in the catchments (SSY = 1.94 Mg ha−1 yr−1; σ = 1.22). The catchments with more circular shapes and steeper slopes were those with higher AICN‐OUT. The structural SC maps – removing the rainfall erosivity influence – allowed evaluating the actual role played by the post‐fire practices that reduced SC (
= − 1.19%; σ = 0.41); while functional SC was linked to the actual change of SC (
= + 5.32%; σ = 0.62). Hillslope treatments resulted in significant changes on AICN‐OUT at sub‐catchment scale with certain disconnectivity. A good and positive correlation was found between the SSY and the changes of AICN‐OUT. However, the coarse DEM resolution explained the lack of effect of the rock check‐dams – located on the secondary channels – on AICN‐OUT. AICN‐OUT proved to be a useful tool for decision making in post‐fire restoration, but an optimal input data is still necessary to refine calculations.
Evaluating the use of calcium hydrogen phosphate dihydrate as a mineral‐based fire retardant for application in melamine‐urea‐formaldehyde (MUF)‐bonded wood‐based composite materials
Authors: Ozyhar Tomasz , Tschannen Christof , Thoemen Heiko , Zoppe Justin O. 
Published: July 2021

SummaryCalcium hydrogen phosphate dihydrate (DCPD) was evaluated for its potential as a mineral fire retardant (FR) for application in melamine‐urea‐formaldehyde (MUF)‐bonded wood composites. The efficacy as FR was studied in melamine‐urea‐formaldehyde (MUF)‐bonded three‐layer particleboard as a function of addition quantities of 10‐, 20‐ and 30 wt%. Resistance to fire and mechanical properties were determined by measuring the self‐extinguishing time after flame exposure and internal bond strength, respectively. Combustion behavior was examined on samples with 20 wt% DCPD addition by performing cone calorimetry experiments. The efficacy of DCPD was evaluated by determining the heat release, total heat release rate, smoke production, and smoke production rate and compared to another promising mineral‐based fire‐retardant composition (FRC) based on hydroxyapatite (HA) with deliquescent salt and HA alone. The effect of FR on the curing behavior of MUF in relation to mechanical properties was determined through viscosity measurements of MUF with 10 wt% addition of FR. The results confirmed the fire‐retardant characteristics of DCPD in wood composites, albeit at higher application rates when compared to the FRC, however with no negative impact on resin curing time or mechanical strength. Based on the demonstrated compatibility in MUF, DCPD is considered a promising mineral extender of other FRs for application in UF‐based wood composites.
Post‐drought increase in regional‐scale groundwater nitrate in southwest Germany
Authors: Jutglar Karuna , Hellwig Jost , Stoelzle Michael , Lange Jens 
Published: July 2021

AbstractElevated nitrate concentrations in groundwater are a common challenge for water management. One important factor in this context is higher frequencies and intensities of wet‐dry cycles that may cause increased nitrate concentrations in groundwater due to nitrate flushes after drought termination. Yet systematic studies on regional‐scale impacts of droughts on groundwater nitrate concentrations are missing so far. Here we analyzed time series of 44 shallow groundwater wells and 41 springs all across the German Federal State Baden‐Wuerttemberg from 2000 to 2018 to characterize patterns of post‐drought nitrate increase in groundwater. In general, half of the exceptional nitrate concentrations, which exceeded the 80th percentile of long‐term nitrate measurements, could be related to droughts in the research timeframe. The 2003 drought event stood out in terms of drought severity and post‐drought nitrate concentration increases in our data. The great majority (91%) of all monitoring sites showed at least one exceptionally high nitrate concentration in the 4 years following the 2003 drought event. Springs were mainly located in forests of steep low mountain ranges and wells in cropland of flat river valleys. Therefore, delay times between drought intensity and nitrate concentration increases as well as magnitudes of nitrate concentration increase were diverse among wells and springs. We derived two distinct nitrate response patterns: (i) nitrate increases immediately following drought events (more common for springs and fractured rock aquifers) and (ii) delayed nitrate increases (more common for wells and porous aquifers). Springs generally showed quicker (median of 101 days) but weaker (median of +1.3 mg/L) post‐drought nitrate increases than wells (185 days, +3.4 mg/L). Only few sites exhibited no post‐drought nitrate increase and post‐drought mean‐nitrate concentrations of groundwater reservoirs were extraordinarily high in 2006. Overall, we demonstrate that post‐drought nitrate increase in groundwater is omnipresent, while different landscapes and hydrogeological characteristics create a diverse regional pattern. As severe droughts become more frequent in a changing climate, post‐drought nitrate increase may intensify problems regarding water quality and supply.
Diagnostic performance of the Elecsys SARS‐CoV‐2 antigen assay in the clinical routine of a tertiary care hospital: Preliminary results from a single‐center evaluation
Authors: Mueller Thomas , Kompatscher Julia , La Guardia Mario 
Published: July 2021

AbstractBackgroundThis report describes a manufacturer‐independent evaluation of the diagnostic accuracy of the Elecsys SARS‐CoV‐2 antigen assay from Roche Diagnostics in a tertiary care setting.MethodsIn this single‐center study, we used nasopharyngeal swabs from 403 cases from the emergency department and intensive care unit of our hospital. The reference standard for detecting SARS‐CoV‐2 was the reverse‐transcription polymerase chain reaction (RT‐PCR) assay. Cycle threshold (Ct) values were recorded for positive RT‐PCR assays. The index test was the Elecsys SARS‐CoV‐2 antigen assay. This electrochemiluminescence immunoassay produces results as cutoff index (COI) values, with values ≥1.00 being reported as positive.ResultsOf the 403 cases, 47 showed positive results in RT‐PCR assays. Of the 47 RT‐PCR‐positive cases, 12 showed positive results in the antigen assay. Of the 356 RT‐PCR‐negative cases, all showed negative results in the antigen assay. Thus, the antigen assay showed a sensitivity of 26% (95% CI, 14%‐40%) and specificity of 100% (95% CI, 99%‐100%). Analysis of the relationship between Ct values and COI values in the 47 RT‐PCR‐positive cases showed a correlation coefficient of −0.704 (95% CI, −0.824 to −0.522). The true‐positive rate of the antigen assay for Ct values of 15–24.9, 25–29.9, 30–34.9, and 35–39.9 was 100%, 44%, 8%, and 6%, respectively.ConclusionsThe Elecsys SARS‐CoV‐2 antigen assay has a low sensitivity for detecting SARS‐CoV‐2 from nasopharyngeal swabs. Hence, we decided to not use this assay in the clinical routine of our hospital.
Development of microalgal biofilm for wastewater remediation: from mechanism to practical application
Authors: Hu Yingbing , Xiao Yu , Liao Kang , Leng Yunyue , Lu Qian 
Published: July 2021

AbstractThe high cost of biomass harvesting by centrifugation and high safety risks of collected algal biomass by chemical flocculation are serious problems jeopardizing the industrial implementation of microalgae bio‐products. Recently, microalgae immobilization is regarded as a promising technology with the potential of lowering biomass production cost and ensuring biomass safety in the industry. Therefore, microalgal biofilms, an effective and affordable way to immobilize algal cells, are emerging into the limelight. This paper summarizes the progress achieved in biofilm system design and biofilm formation mechanisms. Newly designed algal biofilm systems are compared to demonstrate their advantages and weaknesses. Besides, mechanisms associated with the two steps –initial attachment of microalgae and biofilm thickening – of biofilm formation are discussed in this paper. Factors such as substratum material, algal strain and operational parameters, which could impact the formation and operation of algal biofilm, are demonstrated. Efforts devoted to the industrial application of algal biofilm to treat wastewater are discussed. The biotechnology of microalgal biofilm is currently at the critical stage of developing from fundamental research to industrial implementation. Undeniably, there are still many problems that limit the wide use of algal biofilm for biomass production and wastewater treatment. In this paper, we present some potential solutions to current problems and discuss the development trends of algal biofilm in the foreseeable future. It is expected that by addressing current problems microalgal biofilm will be widely used at the industrial scale. © 2021 Society of Chemical Industry (SCI).
Clinical characteristics of ulcerative colitis in elderly patients
Authors: Zhu Mingming , Ran Zhihua 
Published: July 2021

AbstractThe incidence of ulcerative colitis (UC) in elderly patients is increasing. Elderly UC patients are likely to exhibit distinct features both at diagnosis and during follow‐up. Age‐related problems, including complications, immune dysfunction, and multidrug use, make the diagnosis and treatment of elderly UC more challenging. Suboptimal treatment considering adverse events leads to poor clinical outcome in elderly UC patients. Here, we reviewed the epidemiology, clinical presentation, medical therapy, colorectal cancer surveillance of UC in elderly patients.