bluuebunny/crossref_metadata_2025 huggingface dataset:
Emulating proton transfer reactions in the pseudo-protic ionic liquid 1-methylimidazolium acetate
Authors: Jacobi Richard , Joerg Florian , Steinhauser Othmar , Schröder Christian
Published: April 2022

Proton transfer reactions can enhance conductivity in protic ionic liquids.
Upcycling agro-industrial blueberry waste into platform chemicals and structured materials for application in marine environments
Authors: Reyes Guillermo , Pacheco Claudia M. , Isaza-Ferro Estefania , González Amaidy , Pasquier Eva , Alejandro-Martín Serguei , Arteaga-Peréz Luis E. , Carrillo Romina R. , Carrillo-Varela Isabel , Mendonça Regis Teixeira , Flanigan Colleen , Rojas Orlando J.
Published: April 2022

Agriculture residues from blueberries were transformed into added-value products and materials using γ-valerolactone and an ionic liquid.
Lignin condensation inhibition and antioxidant activity improvement in a reductive ternary DES fractionation microenvironment by thiourea dioxide self-decomposition
Authors: Zhao Xin , Yang Yingying , Xu Jingyu , Wang Xing , Guo Yanzhu , Liu Chao , Zhou Jinghui
Published: April 2022

Deep eutectic solvents (DESs) as promising green solvents can efficiently remove the lignin component in lignocellulosic biomass.
Photocatalytic degradation of lignin by low content g-C3N4 modified TiO2 under visible light
Authors: Zhang Minpeng , Xu Huitong , Wu Lei , Tan Yu , Kong Dezhi , Yimiti Mamatjan
Published: April 2022

TiO2/g-C3N4 photocatalysts efficiently degraded lignin to obtain small molecule aromatics, which facilitated the efficient utilization of biomass.
Real-time monitoring of the column chromatographic process of Phellodendri Chinensis Cortex part I: end-point determination based on near-infrared spectroscopy combined with machine learning
Authors: Wu Sijun , Cui Tongcan , Li Zheng , Yang Ming , Zang Zhenzhong , Li Wenlong
Published: April 2022

A novel and rapid approach for end-point determination of berberine hydrochloride, phellodendrine chloride and total alkaloids in a column chromatographic process.
A cascade reaction for regioselective construction of pyrazole-containing aliphatic sulfonyl fluorides
Authors: Yang Wen-Fei , Shu Tao , Chen Hong-Ru , Qin Hua-Li , Tang Haolin
Published: April 2022

A copper-catalyzed cascade reaction of α-diazocarbonyl compounds with ethenesulfonyl fluoride for the construction of pyrazole-containing aliphatic sulfonyl fluorides is developed.
One-step laser etching of a bionic hierarchical structure on a silicone rubber surface with thermal and acid/alkali resistance and tunable wettability
Authors: Du Yu , Wu Ting , Xie Heng , Qu Jin-Ping
Published: April 2022

Superhydrophobic silicone rubbers with robust physical and chemical stability have promising application potential in the field of flexible electronics.
Repulsive torques alone trigger crystallization of constant speed active particles
Authors: Le Blay Marine , Morin Alexandre
Published: April 2022

Active particles which repel each other through torques crystallize without reducing their intrinsic speed.
Modeling the dynamic growth and branching of actin filaments
Authors: Xu Wu , Liu Xuheng , Liu Xiaohu
Published: April 2022

As an essential component of the cytoskeleton, actin filaments play a key role in a variety of cellular physiological activities.
New binaries from the SHINE survey
Authors: Bonavita M. , Gratton R. , Desidera S. , Squicciarini V. , D’Orazi V. , Zurlo A. , Biller B. , Chauvin G. , Fontanive C. , Janson M. , Messina S. , Menard F. , Meyer M. , Vigan A. , Avenhaus H. , Asensio Torres R. , Beuzit J.-L. , Boccaletti A. , Bonnefoy M. , Brandner W. , Cantalloube F. , Cheetham A. , Cudel M. , Daemgen S. , Delorme P. , Desgrange C. , Dominik C. , Engler N. , Feautrier P. , Feldt M. , Galicher R. , Garufi A. , Gasparri D. , Ginski C. , Girard J. , Grandjean A. , Hagelberg J. , Henning T. , Hunziker S. , Kasper M. , Keppler M. , Lagadec E. , Lagrange A.-M. , Langlois M. , Lannier J. , Lazzoni C. , Le Coroller H. , Ligi R. , Lombart M. , Maire A.-L. , Mazevet S. , Mesa D. , Mouillet D. , Moutou C. , Müller A. , Peretti S. , Perrot C. , Petrus S. , Potier A. , Ramos J. , Rickman E. , Rouan D. , Salter G. , Samland M. , Schmidt T. , Sissa E. , Stolker T. , Szulágyi J. , Turatto M. , Udry S. , Wildi F.
Published: April 2022

We present the multiple stellar systems observed within the SpHere INfrared survey for Exoplanet (SHINE). SHINE searched for sub-stellar companions to young stars using high contrast imaging. Although stars with known stellar companions within the SPHERE field of view (< 5.5 arcsec) were removed from the original target list, we detected additional stellar companions to 78 of the 463 SHINE targets observed so far. Twenty-seven per cent of the systems have three or more components. Given the heterogeneity of the sample in terms of observing conditions and strategy, tailored routines were used for data reduction and analysis, some of which were specifically designed for these datasets. We then combined SPHERE data with literature and archival data, TESS light curves, andGaiaparallaxes and proper motions for an accurate characterisation of the systems. Combining all data, we were able to constrain the orbits of 25 systems. We carefully assessed the completeness of our sample for separations between 50–500 mas (corresponding to periods of a few years to a few decades), taking into account the initial selection biases and recovering part of the systems excluded from the original list due to their multiplicity. This allowed us to compare the binary frequency for our sample with previous studies and highlight interesting trends in the mass ratio and period distribution. We also found that, when such an estimate was possible, the values of the masses derived from dynamical arguments were in good agreement with the model predictions. Stellar and orbital spins appear fairly well aligned for the 12 stars that have enough data, which favours a disk fragmentation origin. Our results highlight the importance of combining different techniques when tackling complex problems such as the formation of binaries and show how large samples can be useful for more than one purpose.
The incompressible energy cascade rate in anisotropic solar wind turbulence
Authors: Andrés N. , Sahraoui F. , Huang S. , Hadid L. Z. , Galtier S.
Published: April 2022

Context. The presence of a magnetic guide field induces several types of anisotropy in solar wind turbulence. The energy cascade rate between scales in the inertial range depends strongly on the direction of this magnetic guide field, splitting the energy cascade according to the parallel and perpendicular directions with respect to magnetic guide field.

Aims. Using more than two years of Parker Solar Probe (PSP) observations, the isotropy and anisotropy energy cascade rates are investigated. The variance and normalized fluctuation ratios, the kinetic and magnetic energies, and the normalized cross-helicity and residual energy are studied. The connection between the heliocentric distance, the local temperature of the plasma, and the energy cascade components is made.

Methods. Using exact relations for fully developed incompressible magnetohydrodynamic (MHD) turbulence, the incompressible energy cascade rate is computed. In particular, using the isotropy and 2D and slab assumptions, the isotropic, perpendicular, and parallel energy cascade rate components are estimated.

Results. The variance anisotropy ratios, for both velocity and magnetic fields, do not exhibit a dependence with respect to the heliocentric distance r between 0.2 and 0.8 au. While the velocity normalized fluctuation ratio shows a dependence with r, the magnetic normalized fluctuation ratio does not. A strong correlation between the isotropic and anisotropic energy cascade rates and the temperature is found. A clear dominance of the perpendicular cascades over the parallel cascades as PSP approaches the Sun is observed. A dominant 2D cascade and/or geometry over the slab component in slow solar wind turbulence in the largest MHD scales is observed.
An der Katastrophe vorbei
Authors: Pycha Armin , Palermo Salvatore , Krüger Sara , Thaler Stefanie , Clauser Silvia , Comploj Evi , Trenti Emanuela
Published: April 2022

Eine 21-jährige junge sportliche Frau litt seit geraumer Zeit unter Flankenschmerzen bei Flüssigkeitsaufnahme nach sportlicher Aktivität. Die urologische Abklärung zeigte eine Hydronephrose mit einer „Fischhakenform“ und einen medialisierten Ureter. Diese Ureterenge wurde ureterorenoskopisch, endoskopisch-radiologisch und bioptisch abgeklärt ohne dass man zur korrekten Diagnose eines retrocavalen Ureters gelangte. Therapeutisch erfolgte mehrfach eine DJ-Kathetereinlage, dreimal eine Ballondilatation in Narkose und schlussendlich eine Dauerversorgung mit einem DJ-Katheter. Aufgrund der Unzufriedenheit der Patientin wurde ihr eine endoskopische Endopyelotomie mittels Acucise angeboten.
Parental Stress of Children with Autism Spectrum Disorder During the
Coronavirus Pandemic (COVID-19): Experience from Serbia
Authors: Djuric-Zdravkovic Aleksandra , Japundza-Milisavljevic Mirjana , Perovic Dijana
Published: April 2022

Objective Taking care of children with autism spectrum disorder (ASD), as
of children with other developmental disorders, is associated with greater
parental stress. The aim of this study was to determine the prevalence and
impact of integrative and co-morbid ASD-related symptoms on parental stress
levels during the COVID-19 pandemic at four time points. Testing was performed
during significant changes related to the state of the COVID-19 pandemic in
Serbia.

Methods The research sample included 67 parents of children with ASD 4 to
7 years and 6 months of age. The Autism Parenting Stress Index, Gilliam Autism
Rating Scale - Third Edition, diagnostic criteria for ASD from DSM-5 and
Wechsler Preschool and Primary Scale of Intelligence - Fourth Edition were used
to assess the tested abilities.

Results Core behavior (problems of social development and communication
skills) as well as co-morbid behaviors related to ASD (tantrums, aggressive
behavior, self-injurious behavior and difficulties with transitions) caused the
highest degree of parental stress. Post hoc tests that used Bonferroni
correction found that parental stress caused by basic and co-morbid behaviors
gradually decreased from first to fourth measurement, respectively. Sleep and
toilet training problems, as well as co-morbid physical problems, caused the
greatest degree of parental stress during the first measurement. Measuring total
parental stress caused by integrative and co-morbid symptoms related to ASD
showed that it was at the highest level during the first measurement, decreased
during the second measurement and remained unchanged during the third and fourth
measurements.

Conclusion Time, as a repeating factor, during the COVID-19 pandemic has
an effect on lowering the levels of parental stress caused by all examined
ASD-related domains. These results may be useful in creating individual programs
to support parents of children with ASD during the COVID-19 pandemic.
Impact of endoscopic ultrasound-guided gallbladder drainage on reducing costs of reintervention and unplanned readmission: a budget impact analysis
Authors: Chan Shannon Melissa , Chong Marc Ka Chun , Chiu Philip Wai Yan , Ng Enders Kwok Wai , Wong Martin Chi Sang , Teoh Anthony Yuen Bun
Published: April 2022

Background and study aims Endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) is the preferred treatment for patients with acute calculous cholecystitis who are unfit for surgery. The aim of this study was to perform a cost-effective analysis (CEA) comparing EUS-GBD with percutaneous gallbladder drainage (PT-GBD).

Patients and methods CEA was performed on patients recruited for our prior randomized controlled trial. A budget impact model was developed to compare the base-case and scenario of EUS-GBD applications. The costs including peri-procedure and intra-procedure, reinterventions, expenses associated with treatment of adverse events (AEs), costs of hospital stay, subsequent clinic follow-up, and unplanned readmission were included.

Results PT-GBD had a lower total procedure cost per patient (USD$4,375.00) than EUS-GBD (USD$9,397.44). For EUS-GBD, the cost of cautery-enhanced lumen-apposing stent accounted for the major part of the expense (USD$4,910.26). EUS-GBD resulted in a lower expected cost (USD$108.26 vs USD$1,601.54) for a re-procedure. The expected cost per patient in unplanned readmissions in the EUS-GBD group (USD$450.00) was lower than that in the PT-GBD group (USD$1,717.56). Based on the budget impact analysis, the net budget impact per year of introducing EUS-GBD to replace PT-GBD was higher (USD$16,424.10 vs USD$11,433.08). The net budget impact was most sensitive to the cost of stent and linear echoendoscope used in EUS-GBD.

Conclusions The net budget impact per year was higher for introducing EUS-GBD. The cost of the stent accounted for the major cost difference between the two procedures. EUS-GBD saved on the cost in management of AEs, reinterventions, and unplanned readmissions but these did not offset the cost of the stent.
Enantiopure β3-Trifluoromethyl-β3-homoalanine Derivatives: Coupling with Boc-Protected Amino Acids and Conformational Studies of Peptides in Solid State
Authors: Grellepois Fabienne , Saraiva Rosa Nathalie
Published: April 2022

The use of enantiopure β3-trifluoromethyl-β3-alkyl β-amino acids for the design of peptides would contribute to drastically enhance peptide stability in vivo. Moreover, the steric hindrance generated by the substituents on the tetrasubstituted carbon adjacent to the nitrogen function coupled to the electron-withdrawing effect of the trifluoromethyl group is more likely to influence the 3D conformation of the peptide. Herein, we describe a short, scalable and robust method to synthesize N- and/or C-protected enantiopure (R)- and (S)-β3-trifluoromethyl-β3-methyl β-amino acid derivatives and liquid-phase coupling methods suitable for incorporation of Boc-protected amino acids into short α/β- and β-peptides. Conformational studies of some of these original peptides via X-ray diffraction analysis highlighted intraresidue C6 hydrogen bonds within trifluoromethylated amino acids.
Psychoacoustic Measures of Tinnitus
Authors: Henry James A. , Meikle Mary B.
Published: April 2022

This report reviews research from the 1930s to the present that has extended our understanding by investigating the characteristics of tinnitus that can be studied using psychoacoustic techniques. Studies of tinnitus masking and residual inhibition began in the 1970s, leading to the therapeutic use of tinnitus masking and a consequent increase in research devoted to tinnitus measurement. In 1981, the CIBA Foundation symposium on tinnitus advocated general adoption of four tinnitus measures: (1) pitch, (2) loudness, (3) maskability, and (4) residual inhibition. Since then, psychoacoustic research into all four topics has proliferated, yielding many valuable insights and controversies concerning the details of measurement techniques. A consensus has emerged that neither the loudness nor other psychoacoustic measures of tinnitus bear a consistent relation to the severity or perceived loudness of tinnitus. Nevertheless, quantification is needed in clinical trials of proposed treatments and in a variety of other types of tinnitus research. Standardization of techniques for specifying the acoustic parameters of tinnitus thus continues to be an important research goal.

Abbreviations: ABLB = alternating binaural loudness balance, DL = difference limen, FCDS = forced-choice double staircase, MML = minimum masking level, PLU = personal loudness unit, Rl = residual inhibition
Infrasound signals from nontornadic and pre-tornadic storms indistinguishable
Authors: Piccone Ashley
Published: April 2022

Thought to help radar in identifying tornadic storms, infrasound may not work as well as anticipated.
Method for improving the accuracy of fluorescence molecular tomography based on multi-wavelength concurrent reconstruction
Authors: Wang Huiquan , Feng Tianzi , Dong Xinming , Zhao Zhe , Han Guang , Wang Jinhai , Ma Wenjuan , Wang Rong , Liu Minghu , Miao Jinghong
Published: April 2022

A Concurrent-wavelength Reconstruction Algorithm (CRA) based on multi-wavelength information fusion is proposed in this paper that aims to further improve the accuracy of Fluorescence Molecular Tomography (FMT) reconstruction. Combining multi-spectral data with FMT technology, the information of 650 and 750 nm wavelengths near-infrared was used to increase the feature information of the dominant 850 nm wavelength near-infrared effectively. Principal component analysis, which can remove redundant information and achieve data dimensionality reduction, was then utilized to extract the feature information. Finally, tomographic reconstruction of the anomalies was performed based on the stacked auto-encoder neural network model. The comparison results of numerical experiments showed that the reconstruction effect of CRA was superior to the performance of the single wavelength model. The correlation coefficient between CRA reconstructed anomalies’ fluorescence yield values and the real fluorescence yield values remained at 0.95 or more under the noise of different levels of signal-to-noise ratios. Therefore, the CRA proposed in this paper could effectively improve on the ill-posedness of the inverse problem, which could further enhance the accuracy of FMT reconstruction.
Nanoscale plasticity in titania densified alumina ceramics
Authors: Maiti Payel , Sadhukhan Dhrubajyoti , Ghosh Jiten , Mukhopadhyay Anoop Kumar
Published: April 2022

The present study explores the physics behind the loading rate (dP/dt or P˙≈1−1000mNs−1) dependent nanoscale plasticity (NSP) events observed during carefully controlled nanoindentation (NI) experiments on 1, 3, and 5 wt. % Titania Densified Alumina (TDA) ceramics. Characterizations of the TDA ceramics are carried out by x-ray diffraction, field emission scanning electron microscopy (FESEM), and NI techniques. A significant enhancement (∼30%) of the nanohardness of TDA ceramics occur with an enhancement in P˙. The results confirm that both the critical load (Pc) at which micro-pop-in or the NSP events initiate and the corresponding critical depth (hc) are sensitive functions of relative density, size of relatively finer grains, loading rate, and the amount of sintering aids. The experimentally observed empirical power law dependence of all the NSP related parameters on P˙ is rationalized theoretically and qualitatively. It is suggested that the shear induced homogeneous dislocation nucleation underneath the nanoindenter may be the main factor contributing to the occurrence of the NSP events at relatively lower loading rates. However, especially at the relatively higher loading rates, the FESEM based evidence and the data obtained from the related NI experiments suggest that there is a more acute interconnection between the homogeneous dislocation nucleation induced profuse occurrence of the NSP events, shear band formations, and microcrack formation in the TDA ceramics. Finally, the design implications of the present results for the development of better alumina ceramics for load and strain tolerant applications are discussed.
Cylindrical holographic impedance metasurface for OAM vortex wave generation
Authors: Wang Heng , Yu Shixing , Kou Na , Ding Zhao , Zhang Zhengping
Published: April 2022

In this Letter, we present a cylindrical conformal holographic impedance metasurface for orbital angular momentum (OAM) generation. The conformal holographic metasurface is designed by establishing the element library and deducing the formula of holographic tensor impedance modulation. The feasibility of the scheme is verified by simulations and experiments. Simulated and experimental results are in good agreement with theoretical analysis. The results show that OAM vortex wave energy can be generated efficiently by a cylindrical conformal impedance metasurface, which can provide a reference for OAM communication and vortex radars with conformal devices.
Graphics processing unit accelerated lattice Boltzmann method simulations of dilute gravity currents
Authors: Adekanye Damilola , Khan Amirul , Burns Alan , McCaffrey William , Geier Martin , Schönherr Martin , Dorrell Robert
Published: April 2022

Lattice Boltzmann method models offer a novel framework for the simulation of high Reynolds number dilute gravity currents. The numerical algorithm is well suited to acceleration via implementation on massively parallel computer architectures. Here, we present two lattice Boltzmann method models of lock-exchange dilute gravity currents in which the largest turbulent length scales are directly resolved. The three-dimensional simulations are accelerated by exporting computations to a graphics processing unit and are validated against experiments and high-resolution simulations for Reynolds numbers up to 30 000. The lattice Boltzmann method models achieve equivalent accuracy to conventional large-eddy simulation models in the prediction of key flow properties. A conservative analysis of computational performance relative to conventional methods indicates that the presented framework reduces simulation times by two orders of magnitude. Therefore, it can be used as a foundation for the development of depth-resolving models that capture more of the complexity of environmental gravity currents.
Machine learned calibrations to high-throughput molecular excited state calculations
Authors: Verma Shomik , Rivera Miguel , Scanlon David O. , Walsh Aron
Published: April 2022

Understanding the excited state properties of molecules provides insight into how they interact with light. These interactions can be exploited to design compounds for photochemical applications, including enhanced spectral conversion of light to increase the efficiency of photovoltaic cells. While chemical discovery is time- and resource-intensive experimentally, computational chemistry can be used to screen large-scale databases for molecules of interest in a procedure known as high-throughput virtual screening. The first step usually involves a high-speed but low-accuracy method to screen large numbers of molecules (potentially millions), so only the best candidates are evaluated with expensive methods. However, use of a coarse first-pass screening method can potentially result in high false positive or false negative rates. Therefore, this study uses machine learning to calibrate a high-throughput technique [eXtended Tight Binding based simplified Tamm-Dancoff approximation (xTB-sTDA)] against a higher accuracy one (time-dependent density functional theory). Testing the calibration model shows an approximately sixfold decrease in the error in-domain and an approximately threefold decrease in the out-of-domain. The resulting mean absolute error of ∼0.14 eV is in line with previous work in machine learning calibrations and out-performs previous work in linear calibration of xTB-sTDA. We then apply the calibration model to screen a 250k molecule database and map inaccuracies of xTB-sTDA in chemical space. We also show generalizability of the workflow by calibrating against a higher-level technique (CC2), yielding a similarly low error. Overall, this work demonstrates that machine learning can be used to develop a cost-effective and accurate method for large-scale excited state screening, enabling accelerated molecular discovery across a variety of disciplines.
Preferential orientation of tracer spheroids in evolving Taylor–Green vortex flow
Authors: Jayaram Rohith , Jie Yucheng , Zhao Lihao , Andersson Helge I.
Published: April 2022

Rod- and disk-like particles preferentially align parallel and perpendicular, respectively, to the fluid vorticity, both at the early as well as later stages of the unsteady Taylor–Green vortex (TGV) flow. The early stage of the flow is laminar and comprises anisotropic large-scale Taylor–Green structures, while the later stages resemble homogeneous isotropic turbulence with Kolmogorov-type small-scale structures. The reason for the orientational behavior of inertialess spheroids in the early stage of the TGV-flow has been sought by examining the alignments of spheroidal particles, not only with vorticity but also with Lagrangian stretching and compression directions of the fluid elements in our earlier paper [Jayaram et al., “Alignment and rotation of spheroids in unsteady vortex flow,” Phys. Fluids. 33, 033310 (2021)]. This article is a sequel to the above paper in which the spheroids' alignments are studied locally, in contrast to the volume-averaged statistics studied previously, to observe the influence of the local flow field on the spheroidal alignment. It has been observed through our studies that the alignments vary periodically in space and these variations can be associated with the large-scale periodicity of the flow field originating from the initial conditions of the TGV flow. Additionally, the intense vortex stretching in the early stages of the flow evolution is seen to be largely influencing the orientation of the spheroids.
Damage-failure transition under consecutive dynamic and very high cycle fatigue loads
Authors: Bannikov Mikhail , Oborin Vladimir , Bayandin Yuriy , Ledon Dmitry , Kiselkov Dmitriy , Savinykh Andrey , Garkushin Gennady , Razorenov Sergey , Naimark Oleg
Published: April 2022

The Foreign Object Damage problem is considered as the damage tolerance statement for consecutive loading tests, which include the shock-wave loading (by explosive generator) of massive planar targets (aluminum alloy AlMg6) to provide a billet for the specimen machining with controlled damage that is the analogous material of the fan blades subjected to high-speed collision with solid particles. These samples were used to perform high cycle fatigue and very high cycle fatigue tests with the ultrasonic testing machine, which allows fatigue loading for 108–1010 cycles with an amplitude of up to several tens of micrometers and a frequency of 20 kHz. It is shown that the fatigue strength of AlMg6 alloy specimens pre-loaded by shock in the 109 cycle regime reduces by 24%. The fatigue damage-failure transition and crack initiation were studied by the amplitude–frequency analysis of higher harmonics associated with the influence of defects on the effective elastic properties. The structural study of the fracture surface for the specimens after consecutive loading was conducted using the profilometry data to identify the roughness scale invariants induced by defects for corresponding areas responsible for the staging of fatigue damage-failure transition. The scale invariants and corresponding lengths were used for the formulation of the generalized Paris law for the crack advance in the damaged material.
Control of line voltage unbalance factor in three-phase distribution grids caused by single-phase photovoltaic systems
Authors: Bot Youcef , Naama Bakhta , Yousfi Abdelkader , Allali Ahmed , Denai Mouloud
Published: April 2022

This study investigates the use of photovoltaic systems to regulate the voltage amplitude of electric power networks and to analyze their impact on the stability of Line Voltage Unbalance Factor (LVUF). It will be shown that instability of the LVUF can occur when single-phase domestic photovoltaic systems equipped with a voltage controller are connected to the three-phase low voltage network. The degradation of the LVUF is one of the problems to be avoided in three-phase electrical networks. To address this problem, this paper presents a complementary algorithm to be applied on the existing controller of the photovoltaics system. This algorithm calculates the optimum reference voltage for the controller, to keep the voltage amplitude within the permitted range, and at the same time prevent the degradation of the LVUF.
Thermodynamics and hydrodynamics of spontaneous and forced imbibition in conical capillaries: A theoretical study of conical liquid diode
Authors: Iwamatsu Masao
Published: April 2022

Thermodynamics and hydrodynamics of spontaneous and forced imbibition of liquid into conical capillaries are studied to assess the feasibility of a conical liquid diode. The analytical formulas for the Laplace pressure and the critical Young's contact angle of the capillary for the onset of spontaneous imbibition are derived using the classical capillary model of thermodynamics. The critical contact angle below which the spontaneous imbibition can occur belongs to the hydrophilic region for the capillary with a diverging radius while it belongs to the hydrophobic region for the capillary with a converging radius. Thus, by choosing Young's contact angle between these two critical contact angles, only the spontaneous imbibition toward the converging radius occurs. Therefore, the capillary with a converging radius acts as the forward direction and that with a diverging radius as the reverse direction of diode. Even under the external applied pressure, the free-energy landscape implies that the forced imbibition occurs only to the forward direction by tuning the applied pressure. Furthermore, the scaling rule of the time scale of imbibition is derived by assuming Hagen–Poiseuille steady flow. Again, the time scale of the forward direction is advantageous compared to the reverse direction when the imbibition to both directions is possible. Therefore, our theoretical analysis shows that a conical capillary acts as a liquid diode.
Granular mixtures discharging through a silo with lateral orifice
Authors: Anyam Vamsi Krishna Reddy , Anki Reddy K.
Published: April 2022

Here, we studied the flow dynamics of a mixture of dumbbells and disks flowing through an orifice situated on the lateral wall of a two-dimensional silo using the discrete element method. When two constituent parts of a dumbbell are simultaneously in contact with either a disk or one part of another dumbbell, it hinders the relative motion of both the particles. An increase in the fraction of dumbbells increases the number of contacts exhibiting the aforementioned mechanism, thus increasing the dynamic friction. This leads to a decrease in the flow rate with an increase in the fraction of dumbbells. To relate the flow rate with the fraction of dumbbells and the orifice width, we proposed modified Beverloo's law scaling. Moreover, we presented coarse-grained flow fields, which reveal the presence of stagnant zones that hinder the free flow of particles adjacent to them.
Equilibrium–nonequilibrium ring-polymer molecular dynamics for nonlinear spectroscopy
Authors: Begušić Tomislav , Tao Xuecheng , Blake Geoffrey A. , Miller Thomas F.
Published: April 2022

Two-dimensional Raman and hybrid terahertz-Raman spectroscopic techniques provide invaluable insight into molecular structures and dynamics of condensed-phase systems. However, corroborating experimental results with theory is difficult due to the high computational cost of incorporating quantum-mechanical effects in the simulations. Here, we present the equilibrium–nonequilibrium ring-polymer molecular dynamics (RPMD), a practical computational method that can account for nuclear quantum effects on the two-time response function of nonlinear optical spectroscopy. Unlike a recently developed approach based on the double Kubo transformed (DKT) correlation function, our method is exact in the classical limit, where it reduces to the established equilibrium-nonequilibrium classical molecular dynamics method. Using benchmark model calculations, we demonstrate the advantages of the equilibrium–nonequilibrium RPMD over classical and DKT-based approaches. Importantly, its derivation, which is based on the nonequilibrium RPMD, obviates the need for identifying an appropriate Kubo transformed correlation function and paves the way for applying real-time path-integral techniques to multidimensional spectroscopy.
Computational optimal transport for molecular spectra: The semi-discrete case
Authors: Seifert Nathan A. , Prozument Kirill , Davis Michael J.
Published: April 2022

Comparing a discrete molecular spectrum to a continuous molecular spectrum in a quantitative manner is a challenging problem, for example, when attempting to fit a theoretical stick spectrum to a continuous spectrum. In this paper, the use of computational optimal transport is investigated for such a problem. In the optimal transport literature, the comparison of a discrete and a continuous spectrum is referred to as semi-discrete optimal transport and is a situation where a metric such as least-squares may be difficult to define except under special conditions. The merits of an optimal transport approach for this problem are investigated using the transport distance defined for the semi-discrete case. A tutorial on semi-discrete optimal transport for molecular spectra is included in this paper, and several well-chosen synthetic spectra are investigated to demonstrate the utility of computational optimal transport for the semi-discrete case. Among several types of investigations, we include calculations showing how the frequency resolution of the continuous spectrum affects the transport distance between a discrete and a continuous spectrum. We also use the transport distance to measure the distance between a continuous experimental electronic absorption spectrum of SO2 and a theoretical stick spectrum for the same system. The comparison of the theoretical and experimental SO2 spectra also allows us to suggest a theoretical value for the band origin that is closer to the observed band origin than previous theoretical values.
Measurements of cyclotron resonance of the interfacial states in strong spin–orbit coupled 2D electron gases proximitized with aluminum
Authors: Chauhan Prashant , Thomas Candice , Lindemann Tyler , Gardner Geoffrey C. , Gukelberger J. , Manfra M. J. , Armitage N. P.
Published: April 2022

Two dimensional electron gases (2DEGs) in InAs quantum wells proximitized by aluminum are promising platforms for topological qubits based on Majorana zero modes. However, there are still substantial uncertainties associated with the nature of electronic states at the interface of these systems. It is challenging to probe the properties of these hybridized states as they are buried under a relatively thick aluminum layer. In this work, we have investigated a range of InAs/In1−xGaxAs heterostructures with Al overlayers using high precision time-domain THz spectroscopy (TDTS). Despite the thick metallic overlayer, we observe a prominent cyclotron resonance in a magnetic field that can be associated with the response of the interfacial states. Measurements of the THz range complex Faraday rotation allow the extraction of the sign and magnitude of the effective mass, density of charge carriers, and scattering times of the 2DEG despite the close proximity of the aluminum layer. We discuss the extracted band parameters and connect their values to the known physics of these materials.
Deep learning method for fast prediction of film cooling performance
Authors: Li Zuobiao , Su Liangjun , Wen Fengbo , Zeng Jun , Wang Songtao , Zhang Jian
Published: April 2022

This study examines the predictive capability of deep learning method for adiabatic film cooling effectiveness distribution with variable operating conditions and geometric layouts. A conditional generative adversarial network is trained to establish nonlinear mapping from input to output. We embed the boundary condition information directly into the input tensor, thereby imparting the capability to address variable operating conditions. The processed input tensors include different blowing ratios M, incoming turbulence intensity Tu, geometry profile controlled by the inclination angle ϕ, compound angle θ, number of hole rows n, pitch between hole rows Px, and span-wise hole pitch Py. The output data are adiabatic film cooling effectiveness fields generated by Reynolds-averaged Navier–Stokes simulations. The prediction results are in good agreement with the computational fluid dynamics results in terms of various statistical assessments. Furthermore, compared with conventional methods of solving Navier–Stokes equations, predictions based on deep learning result in better response times. Therefore, the method proposed in this study is of high significance in the early design of cooling structures for turbine blades.
Study on the interfacial dynamics of free oscillatory deformation and breakup of single-core compound droplet
Authors: Peng Feng , Wang Zhaohui , Fan Yiwei , Yang Qianwen , Chen Jie
Published: April 2022

Compound droplets are usually taken as microcontainers for biomedical and material encapsulation applications in which a good understanding of the free oscillatory deformation and breakup behavior is essential. In this work, the dynamics of free oscillatory deformation and breakup of a single-core compound droplet with an initial ellipsoidal shell was investigated numerically using the volume-of-fluid method. The effects of droplet diameter and the outer droplet initial deformation parameter are considered. Four outcomes are identified: oscillatory deformation, separation, separation breakup, and breakup. The evolution of the kinetic energy and pressure field of the compound droplet for the four typical outcomes is also analyzed in detail. A clear boundary exists between the first and the latter three outcomes (initial deformation parameters of 0.600–0.773), while the critical factor for the latter three outcomes is the inner and outer droplet diameter ratio. The oscillatory deformation is characterized by the inner and outer droplet undergoing a finite deformation and subsequent oscillatory behavior, with the maximum deformation of the inner and outer droplets being related to the energy transfer between the two, and the outer droplet being a periodic decaying oscillation, while the inner droplet is a large deformation oscillation interspersed with a small deformation oscillation. Separation, separation breakup, and breakup are characterized by breakup at the inner or outer interface during deformation; separation and breakup times are largely dependent on droplet diameter and the initial deformation parameter of the outer droplet; and the neck width at separation is also analyzed in detail.
A perspective on the future of transportable optical lattice clocks
Authors: Takamoto M. , Tanaka Y. , Katori H.
Published: April 2022

The unprecedented stability and accuracy of optical atomic clocks extend their role not only in frequency metrology but also in fundamental physics and geodesy. In particular, excellent stability of optical lattice clocks accessing a fractional uncertainty of 10−18 in less than an hour opens a new avenue for chronometric leveling, which resolves a height difference of one cm in a short averaging time. However, for field use of such clocks, there remains a challenge in developing a transportable system that can operate outside the laboratory. In this Perspective, we describe transportable optical lattice clocks and discuss their future applications to chronometric leveling.
Reynolds number dependence of turbulent heat transfer over irregular rough surfaces
Authors: Kuwata Y.
Published: April 2022

To study the scaling of turbulent heat transfer over a rough surface, we performed a series of direct numerical simulations on turbulent heat transfer over a three-dimensional irregular rough surface with varying the friction Reynolds numbers and relative roughness values. We considered rough surfaces with three different relative roughness values of 1/1.9, 1/4.3, and 1/9.0, and the simulations were performed at three friction Reynolds numbers of 115, 250, and 550. The temperature was treated as a passive scalar with a Prandtl number of unity. Regarding the scaling of the Reynolds analogy factor, which is defined as the ratio of the doubled Stanton number to the skin friction coefficient, a correlation function with the skin friction coefficient, equivalent roughness, and Prandtl number provides an accurate account of the effects of relative roughness, roughness Reynolds number, and friction Reynolds number. For scaling the turbulent momentum and energy fluxes, we introduced the decomposition of the turbulent fluxes into the smooth wall profiles at matched friction Reynolds numbers and their deviatoric components. The baseline smooth wall profile was found to account for the effect of the friction Reynolds number, while the deviatoric component incorporated the effect of the roughness Reynolds number. The dispersion fluxes, namely, the dispersive covariance and dispersion heat flux, were dominantly affected by the roughness Reynolds number rather than the friction Reynolds number. To obtain a better understanding of the effect of wall roughness on the momentum and heat transfer mechanisms, we analyzed the spatial and time-averaged momentum and energy equations and discussed the physical mechanisms that caused a decrease in the mean velocity and temperature from smooth wall profiles.
Coupling characteristics of bubbles with a free surface initially disturbed by water waves
Authors: Liu Liangtao , Wang Jinxiang , Tang Kui
Published: April 2022

The interactions between bubbles and water waves have important applications in ocean engineering, and their coupling characteristics are strongly associated with the wave phase angle, wavelength, and wave amplitude. Based on the assumption that the liquid is inviscid and incompressible, the coupling characteristics between bubbles and water waves are solved by the Euler equations with the finite volume method, and the bubble surface and water wave surface are tracked by the front tracking method. The accuracy of the numerical method is verified by comparison with a spark-generated bubble experiment. Compared with the bubble near the initially plane free surface, the rising height of the water spike is reduced by water waves in the crest state, where a concave shape forms on the falling water wave during bubble contraction when the wavelength λ≤ 4.00 and the wave amplitude h≥ 0.364. The rising height of the water spike is significantly strengthened by water waves in the trough state with smaller wavelengths and larger wave amplitudes, which produce a thinner and higher water spike. The bubble cycle is shortened by water waves in the crest state with smaller wavelengths and prolonged by water waves in the trough state with smaller wavelengths and larger wave amplitudes. The results presented in this paper provide guidance for the study of underwater explosions in complex water wave environments.
Inspiratory leakage flow fraction for surgical masks with varying gaps and filter materials
Authors: Xi Jinxiang , Barari Kian , Si Xiuhua April , Abdollahzadeh Jamalabadi Mohammad Yaghoub , Park Jay Hoon , Rein Michael
Published: April 2022

Leakage flows due to a poor fit can greatly reduce the mask protection efficiency. However, accurate quantification of leakages is lacking due to the absence of standardized tests and difficulties in quantifying mask gaps. The objective of this study is to quantify the leakage flows around surgical masks with gaps of varying areas and locations. An integrated ambient–mask–face–airway model was developed with a pleated surgical mask covering an adult's face, nose, and chin. To study the gap effects, the mask edge along the facile interface was divided into different domains, which could be prescribed either as the mask media or air. A low Reynolds number k-ω turbulence model with porous media was used to simulate inspiratory flows. Experimentally measured resistances of two surgical masks were implemented in porous media zones. Results show that even a small gap of 1-cm2 area could cause a 17% leakage. A gap area of 4.3 cm2 at the nose bridge, the most frequent misfit when wearing a surgical mask, led to a leakage of 60%. For a given mask, the increase rate of leakage slowed down with the increasing gap area. For a given gap, the leakage fraction is 30–40% lower for a mask with a resistance of 48.5 Pa than a mask of 146.0 Pa. Even though the flow dynamics were very different among gaps at different locations, the leakage intensity appeared relatively insensitive to the gap location. Therefore, correlations for the leakage as a function of the gap area were developed for the two masks.
Density functional theory of water with the machine-learned DM21 functional
Authors: Palos Etienne , Lambros Eleftherios , Dasgupta Saswata , Paesani Francesco
Published: April 2022

The delicate interplay between functional-driven and density-driven errors in density functional theory (DFT) has hindered traditional density functional approximations (DFAs) from providing an accurate description of water for over 30 years. Recently, the deep-learned DeepMind 21 (DM21) functional has been shown to overcome the limitations of traditional DFAs as it is free of delocalization error. To determine if DM21 can enable a molecular-level description of the physical properties of aqueous systems within Kohn–Sham DFT, we assess the accuracy of the DM21 functional for neutral, protonated, and deprotonated water clusters. We find that the ability of DM21 to accurately predict the energetics of aqueous clusters varies significantly with cluster size. Additionally, we introduce the many-body MB-DM21 potential derived from DM21 data within the many-body expansion of the energy and use it in simulations of liquid water as a function of temperature at ambient pressure. We find that size-dependent functional-driven errors identified in the analysis of the energetics of small clusters calculated with the DM21 functional result in the MB-DM21 potential systematically overestimating the hydrogen-bond strength and, consequently, predicting a more ice-like local structure of water at room temperature.
A new hybrid lattice-Boltzmann method for thermal flow simulations in low-Mach number approximation
Authors: Wang Guanxiong , Zhao Song , Boivin Pierre , Serre Eric , Sagaut Pierre
Published: April 2022

A new low-Mach algorithm for the thermal lattice Boltzmann method (LBM) is proposed aiming at reducing the computational cost of thermal flow simulations in the low Mach number limit. The well-known low Mach number approximation is adopted to accelerate the simulations by enlarging the time step through re-scaling the psuedoacoustic speed to the same order of the fluid motion velocity. This specific process is inspired by the similarity between the artificial compressibility method and the isothermal LBM and is further extended to its thermal counterpart. It must be emphasized that such low-Mach acceleration strategy is in a general form, thus can be easily applied to other compressible LB methods. The present method overcomes the drawback of the classical pressure gradient scaling method due to the pressure gradient changing. The new algorithm is validated by various well-documented academic test cases in laminar [one dimensional gravity column, 2D (two dimensional) rising thermal bubble, and 2D differentially heated square cavity] and turbulent [3D (three dimensional) Taylor–Green vortex and 3D heated cylinder] regimes. All the results show excellent agreement with the reference data and high computational efficiency.