bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bis‐β‐(diketonates) Zn(II) complexes substituted with thiophene: Electropolymerization, homogeneous and heterogeneous catalysis for ring opening polymerization of lactide
Authors: González Darío M. , Cruz Nicole B. , Hernández Loreto A. , Oyarce Jocelyn , Benavente Rosario , Manzur Carolina 
Published: January 2020

ABSTRACTTwo Bis‐β‐diketonate zinc (II) complexes were synthesized using 1‐(thiophen‐2‐yl)butane‐1,3‐dione and 1‐(thiophen‐2‐yl)‐3‐(thiophen‐3‐yl)propane‐1,3‐dione as ligands. By electropolymerization of their thiophenyl groups, the metallopolymers deposited on FTO electrodes were obtained. The main objective was to study the reactivity of these compounds as ROP catalysts for PLA synthesis, using directly the zinc complexes (homogeneous catalysis) and also the modified electrodes with metallopolymers (heterogeneous catalysis). The homogeneous catalysis studies allowed the optimization of the polymerization conditions, such as reaction time, catalyst concentration, and the use of benzyl alcohol as cocatalyst, as well as their influence on the conversion rate, average molecular weight and polydispersity of PLA, using rac‐LA and L‐LA as monomers. Also, the effect on tacticity and thermal properties were discussed. Finally, the ROP studies using immersed modified electrodes in the polymerization medium were carried out under optimized experimental conditions. These tests were positive for one of the studied compounds, reaching conversions of up to 67%. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 557–567
Semicrystalline poly(vinyl ether)s with high and phototunable glass transition temperature: application for thermally stable and reworkable adhesives
Authors: Ito Shotaro , Akiyama Haruhisa , Mori Miyuki , Yoshida Masaru , Kihara Hideyuki 
Published: January 2020

ABSTRACTThe photoinduced solid–liquid phase transition of azobenzene‐based polymers is an attractive method to synthesize stimuli‐responsive functional materials. As the structure–property relationships of such materials are not fully understood, a new class of polymer backbone, that is, poly(vinyl ether) (PVE), was studied for the development of azobenzene‐based polymers with high thermal stability. For this purpose, a series of azobenzene‐based PVEs with different monomer structures were synthesized using a Lewis acid catalyst‐based cationic polymerization method. Typical PVEs are viscous polymers with low glass‐transition temperatures (Tg's). The flexibility of the polymer backbone improves with the use of alkylene spacers, changing the order of alignment of the mesogenic azobenzene moieties attached to the backbone, leading to high Tg's of the azobenzene‐based PVEs. One of the synthesized PVEs shows a high glass‐transition temperature of 94 °C, which is 14 °C higher compared to that of the corresponding polymethacrylate. Furthermore, the PVE exhibits photoinduced solid–liquid phase transition from the semicrystalline state. This phase transition material, with its high thermal stability, has the potential for broader applications, such as for the phototuning of adhesion. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 568–577
Plasma‐activated water to improve the stress tolerance of barley
Authors: Gierczik Krisztián , Vukušić Tomislava , Kovács László , Székely András , Szalai Gabriella , Milošević Slobodan , Kocsy Gábor , Kutasi Kinga , Galiba Gábor 
Published: January 2020

AbstractIt is shown that plasma‐activated water (PAW) improves tolerance against combined low temperature and hypoxia stresses during germination. Due to PAW's effect on the antioxidant system, PAW pretreatment mitigates the reducing effect on plant growth of the hydroponically applied NaCl. PAW pretreatment reduces the salt‐stress‐induced decrease of the cysteine and γ‐glutamylcysteine content and improves the plant's recovery after NaCl stress. PAW pretreatment also modifies the NaCl‐induced changes in carotenoid content, especially, β‐carotenes and xanthophylls. These compounds, together with glutathione can reduce salt‐induced damage through the removal of excess reactive oxygen species, which could be the basis of the protective effect of PAW.
87Sr/86Sr isotope ratios in rocks determined using inductively coupled plasma tandem mass spectrometry in O2 mode without prior Sr purification
Authors: Liu Xiaoming , Dong Shuofei , Yue Yahu , Guan Qiuyun , Sun Yali , Chen Shengsheng , Zhang Jiuyuan , Yang Yibo 
Published: January 2020

RationaleAn inductively coupled plasma tandem mass spectrometry (ICP‐MS/MS) instrument can be developed to determine 87Sr/86Sr ratios with an external precision better than 0.05% relative standard deviation (RSD) in “mass shift” mode without prior Sr purification. Previous studies suggested using CH3F, N2O, and SF6 as reaction gases for this method because a better reaction rate can be achieved with Sr+ than with O2 in the reaction cell. However, these gases are not commonly used in general chemistry laboratories, and processes using these gases are difficult to implement quickly due to regulations. We aim to develop a rapid method that can be applied to many samples for the accurate determination of 87Sr/86Sr isotope ratios with precision below 0.1% RSD (or approximately to the fourth decimal place).MethodsWe evaluated the accuracy and precision of 87Sr/86Sr ratios in certified reference materials and different rock types determined using ICP‐MS/MS with O2 as the reaction gas in comparison with those determined using the multicollector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) method.ResultsThis study showed that by using the ICP‐MS/MS method, the 87Sr/86Sr ratios of BCR‐2 and BHVO‐2 do not vary significantly with and without prior Sr purification; when the Sr concentration of the measured solution is within the range of 60–350 ng/mL, there is no significant effect on the measured 87Sr/86Sr ratios. The results also showed that the 87Sr/86Sr ratios of 23 different rock types measured by ICP‐MS/MS and MC‐ICP‐MS methods agree very well.ConclusionsThe precision of the 87Sr/86Sr ratio measured using ICP‐MS/MS varies between 0.0001 and 0.0019 (2SD). This precision is less than that of the MC‐ICP‐MS method but is sufficient for certain applications, such as identifying 87Sr/86Sr ratios in different rock types. These results suggest that the developed ICP‐MS/MS method has the potential for future studies involving the identification of Sr sources.
Stabilization of switched nonlinear systems with dynamic output quantization and disturbances
Authors: Li Can , Lian Jie 
Published: January 2020

SummaryThis paper studies the problem of quantized output feedback stabilization for a disturbed discrete‐time switched system. With the quantized output measurement, an extended state current estimator is constructed to estimate the state and disturbance. In the presence of switches and disturbances, the design of quantization scheme becomes a big challenge to avoid the quantizer saturation and guarantee the control precision. In this setup, the well‐applied time‐triggered method to design the update policy of dynamic quantization parameter is hard to implement. We solve the above problem by proposing a novel event‐triggered update policy of quantization parameter, by which the quantizer update is adaptive to the switching signal and the bound of disturbance difference. Consequently, the quantizer saturation is avoided and, combined with the designed dwell‐time switching law, the system state can converge to the origin. The proposed method is illustrated by a numerical example.
Development of a simple, molecular dynamics‐based method to estimate the thickness of electrical double layers
Authors: Gu Peike , Yang Sen , Liu Xiantang , Yang Gang 
Published: January 2020

AbstractElectrical double layers (EDL) exist for all interfaces and determination of EDL thicknesses remains a difficult task. In this study, molecular dynamics (MD) simulations are employed aiming to develop a simple method for effective evaluation of EDL thicknesses. The EDL thicknesses at clay minerals/water interfaces are calculated by MD simulations and empirical Debye lengths, considering different electrolyte solutions (NaCl, KCl, CsCl, PbCl2 and CaCl2), electrolyte concentrations (0∼1.28 mol/L) and charge locations (tetrahedral and octahedral substitutions). Both methods predict the comparable EDL thicknesses at very low concentrations and more EDL compressions at higher concentrations, while MD simulations show the significant improvements in three aspects, as more rational declining trends with increase of concentrations (Critical for estimating EDL thicknesses especially in highly concentrated solutions), inclusion of ion‐specific effects (More EDL compression for divalent than univalent metal ions, and distinct EDL thicknesses for different alkali ions) and reflection of strong dependence on charge locations (EDL thicknesses differ for montmorillonite and beidellite and have a milder declining rate for montmorillonite). Insights are also offered regarding the microstructure of EDLs, and results promote the understanding of EDLs that determine all interfacial properties and processes.
Controlled Polymerization of ϵ‐Caprolactone using Aluminum and Zinc Complexes with Iminophosphorane Ligands
Authors: Yu Xiaofeng , Zhang Cheng , Wang Zhongxia 
Published: January 2020

AbstractSeveral novel aluminum complexes [Al(R1)2{o‐O C(R)=C(H)P(Ph2)=N)C6H4(3,5‐Me2 ‐pyrazolyl)} (R=Ph, R1=Me, 3; R=Ph, R1=Et, 4; R=tBu, R1=Me, 5) had been prepared. These aluminum complexes were structurally characterized by nuclear magnetic resonance spectroscopy (1H, 13C and 31P) and elemental analyses. The aluminum complex 3 was determined by X‐ray diffraction. The catalytic activities of the aluminum complexes towards the ring‐opening polymerization (ROP) of ϵ‐caprolactone (ϵ‐CL) were investigated. Catalysis of two known zinc complexes with the same ligands, [Zn(Et) {o‐(OC(R)=C(H)P(Ph2)=N)C6H4(3,5‐Me2‐pyrazolyl)}] (R=Ph, 6; R=tBu, 7), in the ROP of ϵ‐CL was also determined. The catalytic results show that these complexes are effective catalysts in the ROP of ϵ‐CL. Kinetics of the polymerization was studied. These polymerizations reaction are consistent with the first‐order kinetic equation. The molecular weight of the polycaprolactone (PCL) is linear with the monomer conversion, and the molecular weight distribution is narrow. These kinetic studies confirm that the catalytic process is controllable.
IoTSim‐Edge: A simulation framework for modeling the behavior of Internet of Things and edge computing environments
Authors: Jha Devki Nandan , Alwasel Khaled , Alshoshan Areeb , Huang Xianghua , Naha Ranesh Kumar , Battula Sudheer Kumar , Garg Saurabh , Puthal Deepak , James Philip , Zomaya Albert , Dustdar Schahram , Ranjan Rajiv 
Published: January 2020

SummaryWith the proliferation of Internet of Things (IoT) and edge computing paradigms, billions of IoT devices are being networked to support data‐driven and real‐time decision making across numerous application domains, including smart homes, smart transport, and smart buildings. These ubiquitously distributed IoT devices send the raw data to their respective edge device (eg, IoT gateways) or the cloud directly. The wide spectrum of possible application use cases make the design and networking of IoT and edge computing layers a very tedious process due to the: (i) complexity and heterogeneity of end‐point networks (eg, Wi‐Fi, 4G, and Bluetooth); (ii) heterogeneity of edge and IoT hardware resources and software stack; (iv) mobility of IoT devices; and (iii) the complex interplay between the IoT and edge layers. Unlike cloud computing, where researchers and developers seeking to test capacity planning, resource selection, network configuration, computation placement, and security management strategies had access to public cloud infrastructure (eg, Amazon and Azure), establishing an IoT and edge computing testbed that offers a high degree of verisimilitude is not only complex, costly, and resource‐intensive but also time‐intensive. Moreover, testing in real IoT and edge computing environments is not feasible due to the high cost and diverse domain knowledge required in order to reason about their diversity, scalability, and usability. To support performance testing and validation of IoT and edge computing configurations and algorithms at scale, simulation frameworks should be developed. Hence, this article proposes a novel simulator IoTSim‐Edge, which captures the behavior of heterogeneous IoT and edge computing infrastructure and allows users to test their infrastructure and framework in an easy and configurable manner. IoTSim‐Edge extends the capability of CloudSim to incorporate the different features of edge and IoT devices. The effectiveness of IoTSim‐Edge is described using three test cases. Results show the varying capability of IoTSim‐Edge in terms of application composition, battery‐oriented modeling, heterogeneous protocols modeling, and mobility modeling along with the resources provisioning for IoT applications.
Effect of super absorbent polymer on microstructural and mechanical properties of concrete blends using granite pulver
Authors: Rajamony Laila Lija , Gurupatham Beulah Gnana Ananthi , Roy Krishanu , B. P. Lim James 
Published: January 2020

AbstractIndustrialization and urbanization has caused a serious impact on the environment due to the vast consumption of energy and eco‐unsustainable production. Therefore, scientists and engineers are placing more effort to design environmentally sustainable systems. To achieve sustainability, one potential solution is to use renewable resources to produce construction materials. The effect on various amounts of admixed super absorbent polymer (SAP) on microstructural, fresh and hardened properties of autogenous cured concrete incorporating Granite Pulver (GP) have been investigated. For this purpose, a small quantity of Portland cement was replaced by GP as 5, 10, 15, and 20%. The SAP was used at volume fractions of 0.1 to 1% to the GP‐concrete blends to counteract self‐desiccation during the hydration of concrete. Along with the GP, fly ash (FA) was also added as filler to improve the workability of GP‐concrete blends. The chemical and microstructural properties of unprocessed GP, fly ash, and cement samples along with the mechanical properties of GP‐concrete blends were investigated through different tests. A total of 627 specimens were prepared for mechanical testing of GP‐concrete blends. The GP along with the SAP increases the compressive strength and flexural strength in comparison with the control mixture by around 1.6 and 6.8% respectively, when a replacement of cement by GP up to 15% was made with an addition of 0.4% of SAP in the mixture.
Ultrasound features prior to 11 weeks' gestation and first‐trimester maternal factors in prediction of hypertensive disorders of pregnancy
Authors: Hanchard T. J. , de Vries B. S. , Quinton A. E. , Sinosich M. , Hyett J. A. 
Published: January 2020

ABSTRACTObjectivesMaternal hypertensive disorders (MHD), including pregnancy‐induced hypertension and pre‐eclampsia, are estimated to occur in 7–10% of pregnancies worldwide and have significant short‐ and long‐term implications for both mother and fetus. This study aimed to determine the association of conventional and novel early first‐trimester ultrasound measures with MHD and whether these ultrasound measures, combined with maternal characteristics and biochemistry, improve the prediction of
MHD.MethodsThis was a prospective cohort study of consecutive women with a singleton pregnancy, attending for an early (5 + 1 to 11 + 0 weeks' gestation) ultrasound examination at a private obstetric ultrasound practice between February 2016 and August 2018. Recorded ultrasound measurements included mean sac diameter, yolk sac diameter, crown–rump length, fetal heart rate (FHR), trophoblast thickness, trophoblast volume (TV) and mean uterine artery pulsatility index. Maternal biochemistry was assessed at 10–14 weeks and included beta‐human chorionic gonadotropin, pregnancy‐associated plasma protein‐A (PAPP‐A), placental growth factor (PlGF) and maternal serum alpha‐fetoprotein. Regression models were fitted for each ultrasound parameter and multiples of the median (MoM) were calculated. All measures were compared between women who had a normotensive outcome and those who subsequently developed MHD. Logistic regression analysis was used to create a prediction model for MHD based on maternal characteristics, ultrasound measurements at 5 + 1 to 11 + 0 weeks' gestation and maternal biochemistry at 10–14 weeks.ResultsIn total, 1141 women were included in the analysis, of whom 1086 (95.2%) were normotensive at delivery and 55 (4.8%) developed MHD. Women who developed MHD weighed significantly more than did normotensive women (P < 0.0001). Mean MoM values for TV (P = 0.006), PAPP‐A (P = 0.031) and PlGF (P = 0.044) were decreased significantly in pregnancies that subsequently developed MHD. The proposed logistic regression model includes maternal weight and height and MoM values for TV, FHR and PlGF, resulting in an area under the receiver‐operating‐characteristics curve of 0.80 (95% CI, 0.75–0.86).ConclusionThe combination of maternal weight and height, TV and FHR, measured prior to 11 weeks' gestation, and first‐trimester PlGF appears to have good predictive value for development of MHD later in pregnancy. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.
Using deep‐learning algorithms to classify fetal brain ultrasound images as normal or abnormal
Authors: Xie H. N. , Wang N. , He M. , Zhang L. H. , Cai H. M. , Xian J. B. , Lin M. F. , Zheng J. , Yang Y. Z. 
Published: January 2020

ABSTRACTObjectivesTo evaluate the feasibility of using deep‐learning algorithms to classify as normal or abnormal sonographic images of the fetal brain obtained in standard axial planes.MethodsWe included in the study images retrieved from a large hospital database from 10 251 normal and 2529 abnormal pregnancies. Abnormal cases were confirmed by neonatal ultrasound, follow‐up examination or autopsy. After a series of pretraining data processing steps, 15 372 normal and 14 047 abnormal fetal brain images in standard axial planes were obtained. These were divided into training and test datasets (at case level rather than image level), at a ratio of approximately 8:2. The training data were used to train the algorithms for three purposes: performance of image segmentation along the fetal skull, classification of the image as normal or abnormal and localization of the lesion. The accuracy was then tested on the test datasets, with performance of segmentation being assessed using precision, recall and Dice's coefficient (DICE), calculated to measure the extent of overlap between human‐labeled and machine‐segmented regions. We assessed classification accuracy by calculating the sensitivity and specificity for abnormal images. Additionally, for 2491 abnormal images, we determined how well each lesion had been localized by overlaying heat maps created by an algorithm on the segmented ultrasound images; an expert judged these in terms of how satisfactory was the lesion localization by the algorithm, classifying this as having been done precisely, closely or irrelevantly.ResultsSegmentation precision, recall and DICE were 97.9%, 90.9% and 94.1%, respectively. For classification, the overall accuracy was 96.3%. The sensitivity and specificity for identification of abnormal images were 96.9% and 95.9%, respectively, and the area under the receiver‐operating‐characteristics curve was 0.989 (95% CI, 0.986–0.991). The algorithms located lesions precisely in 61.6% (1535/2491) of the abnormal images, closely in 24.6% (614/2491) and irrelevantly in 13.7% (342/2491).ConclusionsDeep‐learning algorithms can be trained for segmentation and classification of normal and abnormal fetal brain ultrasound images in standard axial planes and can provide heat maps for lesion localization. This study lays the foundation for further research on the differential diagnosis of fetal intracranial abnormalities. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.
Uterine artery Doppler in singleton pregnancies conceived after in‐vitro fertilization or intracytoplasmic sperm injection with fresh vs frozen blastocyst transfer: longitudinal cohort study
Authors: Cavoretto P. I. , Farina A. , Gaeta G. , Sigismondi C. , Spinillo S. , Casiero D. , Pozzoni M. , Vigano P. , Papaleo E. , Candiani M. 
Published: January 2020

ABSTRACTObjectivePregnancies conceived by frozen blastocyst transfer (FBT) have higher gestational age and weight at birth as compared to those derived by fresh blastocyst transfer. The aim of this study was to evaluate uterine artery pulsatility index (UtA‐PI) in pregnancies conceived by in‐vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) techniques using fresh vs cryopreserved blastocysts.MethodsThis was a prospective longitudinal study of viable singleton IVF/ICSI pregnancies conceived after FBT or fresh blastocyst transfer, that underwent serial ultrasound assessment at San Raffaele Hospital, Milan, Italy at 7–37 gestational weeks. We excluded pregnancies conceived using other assisted reproductive techniques such as egg donation, twin gestation, pregnancy with abnormality and those resulting in miscarriage. Pregnant women underwent ultrasound assessment at 7–10, 11–14, 18–25 and 26–37 weeks' gestation. Mean UtA‐PI was measured using Doppler ultrasound according to The Fetal Medicine Foundation criteria. Pregnancy outcomes were recorded. The primary outcome was mean UtA‐PI measurement and secondary outcomes were gestational age at birth, birth weight and fetal and maternal complications, including small‐for‐gestational age (SGA), pre‐eclampsia and large‐for‐gestational age. UtA‐PI values were made Gaussian after log10 transformation. Analysis of repeated measures using a multilevel linear mixed model (fixed effects and random effects) was performed. The possible effect of other covariates on UtA‐PI Doppler values, including body mass index, SGA and pre‐eclampsia, was also evaluated.ResultsA total of 367 IVF/ICSI cycles, comprising 164 with fresh blastocyst transfer and 203 with FBT, were included and a total of 625 observations (median, 2.5 (range, 1–4)) were collected and analyzed. The FBT group had on average 14% lower UtA‐PI compared with the fresh‐blastocyst‐transfer group. In pregnancies with SGA fetuses, UtA‐PI was 18% higher compared to pregnancies without, irrespective of the study group. Pregnancies that underwent fresh blastocyst transfer had significantly lower birth‐weight centile (43.4 ± 23.3 vs 50.0 ± 23.1; P = 0.007) and a higher rate of SGA (7.9% vs 2.0%; P = 0.008) compared to those that underwent FBT. No significant differences were found between the two groups with respect to gestational age at birth and rates of preterm birth, pre‐eclampsia, gestational diabetes mellitus and large‐for‐gestational age.ConclusionUtA‐PI and the proportion of SGA are lower in IVF/ICSI pregnancies conceived after FBT as compared to fresh blastocyst transfer. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.