bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reversible swelling as a strategy in the development of smart membranes from electrospun polyvinyl alcohol nanofiber mats
Authors: Cimadoro Jonathan , Goyanes Silvia 
Published: February 2020

AbstractThis work presents an electrospun nanofibrous membrane for water treatment, designed to reduce its pores through polymer swelling to retain contaminants, and after that, reopening them for easy cleaning. It consists of a polyvinyl alcohol (PVA) mat crosslinked with a natural agent to avoid water solubility but allow a high swelling of its nanofibers. Then, when the membrane is brought into contact with water, a transitory state occurs during which nanofibers increase their diameter 68%, closing the pores between them. For studying the swelling reversal effect, distilled water filtering was used observing a decrease in the permeate flow over time until a steady state is reached. This phenomenon is explained by the closure of pores, and it is described with a fouling model widely used in the literature. Thanks to this decrease in the pore size, the membrane achieves a rejection rate much higher than conventional PVA electrospun membranes, being capable to retain 20 nm nanoparticles with a rejection rate up to 99%. Swelling is reversible through a simple drying process, which allows reopening the pores and cleaning the fouling easily. Both the membrane and its use strategy extend the capacity of electrospun mats in a sustainable way.
Characterization of mixed solutions of hyperbranched and linear polystyrenes by a combination of size‐exclusion chromatography and analytical ultracentrifugation
Authors: Zhang Miao , Hao Nairong , Gao Yating , Li Lianwei , Ye Xiaodong 
Published: February 2020

AbstractSeparation and characterization on mixed solutions of hyperbranched and linear polystyrenes was achieved using size‐exclusion chromatography (SEC) as the first dimension and analytical ultracentrifugation (AUC) as the second dimension. The results show that linear and hyperbranched polystyrenes with similar hydrodynamic sizes (one fraction from SEC) can be separated by AUC according to the molar mass, and the separation efficiency decreases with the increasing of the retention volume in SEC. Moreover, the molar masses determined by AUC are consistent with the values measured by SEC‐refractive index (RI) and SEC‐multi‐angle light scattering (MALS) detection. Furthermore, the result shows that the separation efficiency decreases with the increasing of the subchain length of hyperbranched polystyrenes. Our study lays a solid foundation for future studies to separate polymers with different topologies by a combination of SEC and AUC.
The relationship of hypertension with obesity and obstructive sleep apnea in adolescents
Authors: Khan Masrur A. , Mathur Kanika , Barraza Giselle , Sin Sanghun , Yang Christina J. , Arens Raanan , Sutton Nicole , Mahgerefteh Joseph 
Published: February 2020

AbstractObjectivesTo assess the independent relationships of obesity and obstructive sleep apnea (OSA) with hypertension/elevated blood pressure (EBP) in adolescent patients.Study DesignA retrospective cohort analysis was performed on 501 patients (age 13‐21 years) with three separate blood pressure measurements within 6 months of polysomnography. EBP was defined as average systolic blood pressure (SBP) ≤120 mm Hg; obesity as body mass index Z‐score ≤1.65; and OSA as obstructive apnea‐hypopnea index <1. Pearson correlations and multivariable analyses were performed to assess the independent effects of the apnea‐hypopnea index and body mass index Z‐score on SBP.ResultsOf 501 patients (mean age 16 ± 2 years), 246 (49%) were male. OSA was present in 329 (66%) patients, obesity in 337 (67%), and EBP in 262 (52%). EBP was present in 70% of obese adolescents and 60% of adolescents with OSA. Univariable correlation showed a significant relationship between SBP, body mass index Z‐score, and apnea‐hypopnea index. Multivariable linear regression analysis showed blood pressure was significantly associated with body mass index Z‐score (β = .46; P < .01), age (β = .25; P < .01), and height Z‐score (β = .14; P < .01), but not apnea‐hypopnea index (β = .01; P = .72).ConclusionsThe relationship between OSA and EBP in adolescents is most closely associated with the degree of obesity. Further studies are needed to assess the effect of the treatment of obesity and OSA on blood pressure in adolescents.
Determination of hazard ratio for progression‐free survival considering the tumor assessment schedule in sample size calculation
Authors: Tanase Takanori 
Published: February 2020

SummaryProgression‐free survival is recognized as an important endpoint in oncology clinical trials. In clinical trials aimed at new drug development, the target population often comprises patients that are refractory to standard therapy with a tumor that shows rapid progression. This situation would increase the bias of the hazard ratio calculated for progression‐free survival, resulting in decreased power for such patients. Therefore, new measures are needed to prevent decreasing the power in advance when estimating the sample size. Here, I propose a novel calculation procedure to assume the hazard ratio for progression‐free survival using the Cox proportional hazards model, which can be applied in sample size calculation. The hazard ratios derived by the proposed procedure were almost identical to those obtained by simulation. The hazard ratio calculated by the proposed procedure is applicable to sample size calculation and coincides with the nominal power. Methods that compensate for the lack of power due to biases in the hazard ratio are also discussed from a practical point of view.
Effects of green tea or green tea catechin on liver enzymes in healthy individuals and people with nonalcoholic fatty liver disease: A systematic review and meta‐analysis of randomized clinical trials
Authors: Mahmoodi Marzieh , Hosseini Razieh , Kazemi Asma , Ofori‐Asenso Richard , Mazidi Mohsen , Mazloomi Seyed Mohammad 
Published: February 2020

AbstractThe therapeutic potential of green tea as a rich source of antioxidants and anti‐inflammatory compounds has been investigated by several studies. The present study aimed to systematically review and analyze randomized clinical trials (RCTs) assessing the effects of green tea, catechin, and other forms of green tea supplementation on levels of liver enzymes. PubMed, SCOPUS, EMBASE, and Cochrane databases were searched until February 2019. All RCTs investigating the effect of green tea or its catechin on liver enzymes including alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin were included. A total of 15 RCTs were included. The overall effect of green tea on liver enzymes was nonsignificant (ALT [Standardized mean difference (SMD)= −0.17, CI −0.42 to 0.08, p = .19], AST [SMD = −0.07, CI −0.43 to 0.29, p = .69], and ALP [SMD = −0.17, CI −0.45 to 0.1, p = .22]). However, subgroup analyses showed that green tea reduced the levels of liver enzymes in participants with nonalcoholic fatty liver disease (NAFLD) but in healthy subjects, a small significant increase in liver enzymes was observed. In conclusion, the results of this study suggest that the effect of green tea on liver enzymes is dependent on the health status of individuals. While a moderate reducing effect was observed in patients with NAFLD, in healthy subjects, a small increasing effect was found.
Quantum embedding for material chemistry based on domain separation and open subsystems
Authors: Mosquera Martín A. , Jones Leighton O. , Ratner Mark A. , Schatz George C. 
Published: February 2020

AbstractThis perspective considers two theories we recently proposed to perform quantum embedding calculations for chemical systems: domain‐separated density functional theory (DS‐DFT) and locally coupled open subsystems (LCOS). The development includes both the fundamentals of each theory as well as potential applications, some technical aspects, and related challenges. DS‐DFT is suited to study intramolecular effects, where one can apply a high level of theory (based on DFT or wave function theory) to a region of interest inside a molecule or solid and lower level theory elsewhere, with smooth switching between the regions. LCOS, in contrast, is a fragment‐based embedding, which offers computational advantages to study intermolecular behavior such as electron hopping, spin‐environment interaction, and charge‐transfer excitations. However, both theories can exchange roles when appropriate. In addition, these theories allow for control of computational scaling of their algorithms. We explore paths to determine the charge‐transfer operator used in LCOS, and suggest an auxiliary energy minimization that can provide a practical estimate to this operator. We also briefly discuss how to implement density fitting techniques in domain separation, and how domain separation can be used for pure wave function‐based embedding.
Au21 cage structures and their magic number tri‐cations
Authors: Ehlert Christopher , Liu Xiaojing J. , Hamilton Ian P. 
Published: February 2020

AbstractWe examine the stability and properties of three Au21 cage structures, one with D3 symmetry and denoted as Au21 (D3), which is novel, and the other two with C2v symmetry. One, denoted as Au21 (C2v‐1), has been previously reported but the other, denoted as Au21 (C2v‐2), is novel. As reference Au21 structures, we also examine a sheet isomer and a compact isomer, Au21 (Cs‐Tetra), formed by adsorbing an Au atom on Au20 (Td). For all structures, we consider charge ranging from −1 to +4. For the Au21 cage structures, a primary property of interest is their spherical aromaticity, as measured by their nucleus independent chemical shift. Our focus is on charge +3 since each gold atom is assumed to contribute one (6s) valence electron, and 18 is a magic number for shell closing. We find that, although Au21 (D3)+3 has the largest aromaticity, it is not the most stable cage species. Surprisingly, Au21 (C2v‐2), which is not even stable as a neutral cage species, is the most stable tri‐cation cage species. We also examine the stability of (neutral) Au21Xn cage structures relative to Au21Xn structures derived from Au21 (Cs‐Tetra) (with X = F, Cl, Br, I and n = 1, 3, 5). We find that, although Au21F3 derived from Au21 (D3) has the largest aromaticity, it is not the most stable Au21F3 cage structure. Nonetheless, all cage structures are stabilized relative to Au21 (Cs‐Tetra) and, remarkably, for the trichlorinated, tribrominated, and triiodineated clusters, at least one cage structure is more stable than its Au21 (Cs‐Tetra) counterpart.
Automation of boron chromatographic purification for δ11B analysis of coral aragonite
Authors: de la Vega Elwyn , Foster Gavin L. , Martínez‐Botí Miguel Angel , Anagnostou Eleni , Field M. Paul , Kim M. Hwan , Watson Paul , Wilson Paul A. 
Published: February 2020

RationaleTo detect the small changes in past pH, the boron isotope ratio of coral carbonates, expressed as the δ11B value, needs to be both precise and accurate (2sd <<1‰). Boron measurements by Multi‐Collector Inductively Coupled Plasma Mass Spectrometry (MC‐ICPMS) require the boron to be carefully purified before analysis, which is time consuming, and requires specialist training. Here, we use the prepFAST‐MC method that enables the automatic extraction of B (up to 25 ng load) from a CaCO3 matrix.MethodsSamples were purified using the prepFAST‐MC automated system with a ~25‐μL column of Amberlite IRA743 resin. Boron isotope measurements were performed by MC‐ICPMS. The effects of matrix load, speed of sample loading onto the column, and blank contamination were tested to evaluate the effects on the purification process. The optimised protocol was tested on various standards and samples of aragonite corals.ResultsThe blank contribution for the approach is ~60 pg and is negligible given our sample size (<0.2% sample size). Efficiency of matrix removal is demonstrated with the addition of up to 1.6 mg of dissolved low‐B calcium carbonate to NIST SRM 951 with no impact on the accuracy of δ11B values. The Japanese Geological Survey Porites reference material JCp‐1, boric acid standard NIST SRM 951, and seawater, all processed on the prepFAST‐MC system, give δ11B values within error of literature values (δ11BJCp‐1 = 24.31 ± 0.20‰ (2sd, n = 20); δ11BNIST 951 = −0.02 ± 0.15‰ (2sd, n = 13) and δ11BSeawater = 39.50 ± 0.06‰ (2sd, n = 2)). Results obtained from the coral Siderastrea siderea purified with the prepFAST‐MC system show an average offset from the manual ion‐exchange protocols of Δδ11B = 0.01 ± 0.28‰ (2sd, n = 12).ConclusionsOur study demonstrates the capacity of the prepFAST‐MC method to generate accurate and reproducible δ11B values for a range of materials, without fractionation, with efficient matrix removal and with negligible blank contribution.
Differential flatness‐based ADRC scheme for underactuated fractional‐order systems
Authors: Li Zongyang , Wei Yiheng , Zhou Xi , Wang Jiachang , Wang Jianli , Wang Yong 
Published: February 2020

SummaryThis article mainly studies the fractional‐order active disturbance rejection control (FOADRC) schemes for the underactuated commensurate fractional‐order systems (FOSs). The FOADRC framework for linear FOSs‐based fractional proportion integration differentiation is constructed by using the fractional‐order tracking differentiator and the fractional‐order extended state observer, and the necessary conditions for the system to have stable controllers are provided. The FOADRC scheme for underactuated FOSs based on differential flatness is proposed. For underactuated FOSs, a set of flat output expressions with a fixed format is given under the controllable condition of the system. Moreover, making the flat output as the equivalent of the system output is simple and easy to analyze and calculate. Subsequently, the FOADRC scheme is designed by using the flat output. Finally, the scheme proposed in this article is verified by a simulation example.
Interfacial Engineering Coupled Valence Tuning of MoO3 Cathode for High‐Capacity and High‐Rate Fiber‐Shaped Zinc‐Ion Batteries
Authors: Liu Yi , Wang Jing , Zeng Yinxiang , Liu Jie , Liu Xiaoqing , Lu Xihong 
Published: February 2020

AbstractAqueous Zn‐ion batteries (ZIBs) have garnered the researchers' spotlight owing to its high safety, cost effectiveness, and high theoretical capacity of Zn anode. However, the availability of cathode materials for Zn ions storage is limited. With unique layered structure along the [010] direction, α‐MoO3 holds great promise as a cathode material for ZIBs, but its intrinsically poor conductivity severely restricts the capacity and rate capability. To circumvent this issue, an efficient surface engineering strategy is proposed to significantly improve the electric conductivity, Zn ion diffusion rate, and cycling stability of the MoO3 cathode for ZIBs, thus drastically promoting its electrochemical properties. With the synergetic effect of Al2O3 coating and phosphating process, the constructed Zn//P‐MoO3−x@Al2O3 battery delivers impressive capacity of 257.7 mAh g−1 at 1 A g−1 and superior rate capability (57% capacity retention at 20 A g−1), dramatically surpassing the pristine Zn//MoO3 battery (115.8 mAh g−1; 19.7%). More importantly, capitalized on polyvinyl alcohol gel electrolyte, an admirable capacity (19.2 mAh cm−3) as well as favorable energy density (14.4 mWh cm−3; 240 Wh kg−1) are both achieved by the fiber‐shaped quasi‐solid‐state ZIB. This work may be a great motivation for further research on molybdenum or other layered structure materials for high‐performance ZIBs.
A multivocal study to improve the implementation of global requirements change management process: A client‐vendor prospective
Authors: Akbar Muhammad Azeem , Mahmood Sajjad , Alsanad Ahmed , Alsanad Abeer Abdul‐Aziz , Gumaei Abdu , Qadri Syed Furqan 
Published: February 2020

AbstractSoftware development is a complex task, and the introduction of multi‐site development teams spread across the globe makes it even harder. Requirement changes during the software development process are inevitable, and failing to manage evolving requirements is one of the contributors to project failures. Requirements change management (RCM) becomes difficult in global software development (GSD) projects due to the need to communicate and coordinate between stakeholders in a distributed environment. This research work aims to identify the factors that have positive impacts on RCM activities in GSD. We conducted a multi‐vocal literature review (MLR) and a questionnaire survey study to identify the RCM success factors. The results of the t‐test (ie, t = 0.0347 and P = .700 > .05) and correlation (rs (25) = 0.573, P = .003) indicates that there is no significant difference between the findings of MLR and the questionnaire survey. The identified factors were further analyzed in the context of client and vendor organizations to better understand the RCM success factors in both types of GSD firms. The findings of this study can provide a useful framework for tackling problems associated with RCM in a GSD environment that is significant to the progression of GSD firms.
Composite floor system with cold‐formed trussed beams and prefabricated concrete slab
Authors: de Seixas Leal Luiz Alberto Araújo , de Miranda Batista Eduardo 
Published: February 2020

AbstractSteel‐concrete composite floor systems represent a common solution for buildings, leading to reduced material consumption and improving the structural strength and flexural stiffness. Lightweight steel frame construction systems, based on the combination of thin‐walled cold‐formed steel members (CFS) and panels (e.g. wood, cementitious, gypsum plaster), may also benefit from the composite behaviour in the case of concrete slabs. In this context, full‐scale experimental tests were conducted to evaluate the structural behaviour of a floor system conceived with 0.95 mm thick CFS trussed beams and prefabricated concrete slabs. An innovative solution for shear connectors was designed and tested in order to ensure full interaction between the CFS trussed beam and the concrete slab. The thin‐walled channel (TWC) connector is based on a lipped channel CFS attached to the top chord of the truss by standard self‐drilling screws. Experimental results indicate efficient behaviour of the TWC shear connectors with improved bending capacity of the floor system.
Bearing monitoring in the wind turbine drivetrain: A comparative study of the FFT and wavelet transforms
Authors: Strömbergsson Daniel , Marklund Pär , Berglund Kim , Larsson Per‐Erik 
Published: February 2020

AbstractWind turbines are often plagued by premature component failures, with drivetrain bearings being particularly subjected to these failures. To identify failing components, vibration condition monitoring has emerged and grown substantially. The fast Fourier transform (FFT) is the major signal processing method of vibrations. Recently, the wavelet transforms have been used more frequently in bearing vibration research, with one alternative being the discrete wavelet transform (DWT). Here, the low‐frequency component of the signal is repeatedly decomposed into approximative and detailed coefficients using a predefined mother wavelet. An extension to this is the wavelet packet transform (WPT), which decomposes the entire frequency domain and stores the wavelet coefficients in packets. How wavelet transforms and FFT compare regarding fault detection in wind turbine drivetrain bearings has been largely overlooked in literature when applied on field data, with non‐ideal placement of sensors and uncertain parameters influencing the measurements. This study consists of a comprehensive comparison of the FFT, a three‐level DWT, and the WPT when applied on enveloped vibration measurements from two 2.5‐MW wind turbine gearbox bearing failures. The frequency content is compared by calculating a robust condition indicator by summation of the harmonics and shaft speed sidebands of the bearing fault frequencies. Results show a higher performance of the WPT when used as a field vibration measurement analysis tool compared with the FFT as it detects one bearing failure earlier and more clearly, leading to a more stable alarm setting and avoidable, costly false alarms.
Maximizing the returns of LIDAR systems in wind farms for yaw error correction applications
Authors: Bakhshi Roozbeh , Sandborn Peter 
Published: February 2020

AbstractWind energy is an important source of renewable energy with significant untapped potential around the world. However, the cost of wind energy production is high, and efforts to lower the cost of energy generation will help enable more widespread use of wind energy. Yaw error reduces the efficiency of turbines as well as lowers the reliability of key components in turbines. Light detection and ranging (LIDAR) devices can correct the yaw error; however, they are expensive, and there is a trade‐off between their costs and benefits. In this study, a stochastic discrete‐event simulation was developed that models the operation of a wind farm. We maximize the net present value (NPV) changes associated with using LIDAR devices in a wind farm and determine the optimum number of LIDAR devices and their associated turbine stay time as a function of number of turbines in the wind farm for specific turbine sizes. The outcome of this work will help wind farm owners and operators make informed decisions about purchasing LIDAR devices for their wind farms.
Correlation functions, entanglement and chaos in the $$ T\overline{T}/J\overline{T} $$-deformed CFTs
Authors: He Song , Shu Hongfei 
Published: February 2020

Abstract
In this paper, we regard the $$ T\overline{T}/J\overline{T} $$
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-deformed CFTs as perturbation theories and calculate the first order correction of the correlation functions due to the $$ T\overline{T}/J\overline{T} $$
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­deformation. As applications, we study the Rényi entanglement entropy of excited state in the $$ T\overline{T}/J\overline{T} $$
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-deformed two-dimensional CFTs. We find, up to the first order perturbation of the deformation, the Rényi entanglement entropy of locally excited states will acquire a non­trivial time dependence. The excess of the Rényi entanglement entropy of locally excited state is changed up to order O(c). Furthermore, the out of time ordered correlation function is investigated to confirm that the $$ T\overline{T}/J\overline{T} $$
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-deformations do not change the maximal chaotic behavior of holographic CFTs up to the first order of the deformations.