bluuebunny/crossref_metadata_2025 huggingface dataset:
A Head-to-Head Comparison of the Medial Sural Artery Perforator versus Radial Forearm Flap for Tongue Reconstruction
Authors: Ng Marcus J.M. , Goh Cindy S.L. , Tan Ngian Chye , Song David H. , Ooi Adrian S.H.
Published: October 2020

Background For tongue reconstruction, the radial forearm flap (RFF) is commonly used. In the last decade, the medial sural artery perforator (MSAP) flap has been successfully used with reportedly superior donor-site outcomes. Our study is the first to compare the RFF and MSAP for reconstruction of partial glossectomy defects (<50% of tongue).

Methods We conducted a retrospective review of 20 patients with partial glossectomy defects reconstructed at a tertiary referral center. Patient demographics, perioperative data, and postoperative complications were analyzed. Objective measures of speech, swallowing, and subjective patient satisfaction with their donor site were recorded.

Results Ten RFF and MSAP were each used, with a mean partial glossectomy defect size of 40.5 and 43.5%, respectively. The MSAP was significantly thicker (7.8 vs. 4.3 mm, p < 0.05) with a longer harvest time (122.5 vs. 75.0 minutes, p < 0.05). There were no cases of free flap failure. Donor-site healing times were comparable, but the MSAP group experienced significantly less donor-site complications (n = 1 vs. n = 7, p < 0.05). Functional outcomes were comparable with 13 patients achieving normal speech and diet after 3 months (MSAP = 6 vs. RFF = 7, p = 1.00). All patients were satisfied with their donor-site outcome with the MSAP group having a marginally higher score.

Conclusion Both flaps are good options for partial glossectomy reconstruction. Though more challenging to harvest, the MSAP gives comparable functional results and has become our first reconstructive option given its superior donor-site outcomes.
Fabrication of nanofiber filters for electret air conditioning filter via a multi-needle electrospinning
Authors: Zhang Rongguang , Wang Han , Zhu Ziming , Chen Rouxi , Chen Xindu , Zeng Jun , Xu Guojie , Wei Chunhua , Zhang Qing , Bai Jianfu , Huang Lixiong
Published: October 2020

Electrospinning technology is considered to be one of the efficient, convenient, and low-cost technologies for preparing nanofibers, which can be applied in various industries, including filtration, catalysis, and energy. Here, aiming at the performance requirements of the nanometer fiber filter membrane for filtering PM2.5, the preparation of the nanofiber filter membrane was realized based on multi-needle electrospinning equipment. Meanwhile, by adding silver nitrate to the spinning solution, a polyvinylidene fluoride antibacterial nanofiber filter layer with high filtration efficiency and low resistance was successfully prepared on the traditional air conditioning filter meshes. We found that four key factors affecting the filtration performance include ambient humidity, substrate meshes, voltage, and production rate. Among them, voltage and production rate are the key factors affecting the filtration performance. According to the development trend of multifunctional nanofiber membranes, the preparation of air conditioning filters with nanofibers as the main filter material was realized, producing air conditioning filter membranes with antibacterial and deodorizing functions. This article provides a reliable experimental basis and empirical reference for the preparation of nanofiber membranes based on multi-needle electrospinning technology.
Experimental and numerical study of nonsmooth maximum bounce height changes in a bouncing ball system
Authors: Karube Shu , Kousaka Takuji , Inaba Naohiko
Published: October 2020

The bouncing ball system is a simple mechanical collision system that has been extensively studied for several decades. In this study, we investigate the bouncing ball’s dynamics both numerically and experimentally. We implement the system using a table tennis ball and paddle vibrated by a shaker. We focus on the relationship between the ball’s maximum bounce height in the long time interval and the paddle’s vibration frequency, observing several stepwise height changes for frequencies of 25–50 Hz, noting this significant characteristic in both our experiments and numerical simulations. We concentrate on this paddle frequency interval because the phenomenon is easy to handle in numerical simulations. Because the observed phenomenon has a simple order, it can be universal and appear in a large class of collision dynamics. Possibly, some researchers have investigated the bouncing ball system in which the nonsmooth maximum bounce height changes occur. However, they may have failed to notice the changes because the maximal height of the ball was not considered.
Optimizing the Super H-mode pedestal to improve performance and facilitate divertor integration
Authors: Knolker M. , Snyder P. B. , Evans T. E. , Wilks T. , Eldon D. , Grierson B. , Jaervinen A. , Jian X. , Laggner F. , McClenaghan J. , McLean A. G. , Osborne T. , Paz-Soldan C. , Scotti F. , Solomon W.
Published: October 2020

Access to Super H-mode is demonstrated for moderately shaped plasmas in agreement with EPED [Snyder et al., Phys. Plasmas 16, 056118 (2009)] predictions. In particular, Super H-mode is realized in a DIII-D shape that is accessible to the JET tokamak. The reduced triangularity of the JET-compatible shape compared to previous Super H-mode plasma shapes does not prevent deep ascension into the so-called Super H-mode “channel.” Operationally, access is enabled and optimized by delaying the neutral beam power injection and, thus, protracting the L–H transition. In highly shaped DIII-D plasmas, the injection of nitrogen sufficient for the establishment of a radiative divertor is shown to be possible during Super H-mode without pedestal degradation. Due to its increased stored energy and radiative divertor integration capabilities, Super H-mode is a promising candidate as operating regime for JET, ITER, and future fusion reactors.
Tuning coupling rate to control oscillation quenching in fractional-order coupled oscillators
Authors: Liu Shutong , Sun Zhongkui , Zhao Nannan
Published: October 2020

Introducing the fractional-order derivative into the coupled dynamical systems intrigues gradually the researchers from diverse fields. In this work, taking Stuart–Landau and Van der Pol oscillators as examples, we compare the difference between fractional-order and integer-order derivatives and further analyze their influences on oscillation quenching behaviors. Through tuning the coupling rate, as an asymmetric parameter to achieve the change from scalar coupling to non-scalar coupling, we observe that the onset of fractional-order not only enlarges the range of oscillation death, but attributes to the transition from fake amplitude death to oscillation death for coupled Stuart–Landau oscillators. We go on to show that for a coupled Van der Pol system only in the presence of a fractional-order derivative, oscillation quenching behaviors will occur. The results pave a way for revealing the control mechanism of oscillation quenching, which is critical for further understanding the function of fractional-order in a coupled nonlinear model.
Plasma triggered spark gap switch for multiple switch synchronization
Authors: Kanchi Sunil , Shukla Rohit , Sharma Archana
Published: October 2020

A four-electrode plasma based triggered spark gap switch is designed for pulsed power applications, which consists of an anode and cathode of a main spark gap switch and an anode and cathode for a trigger pin. The anode and cathode of the trigger pin are coaxially arranged, and the gap between electrodes is 25 μm. A trigger voltage of 200 V is applied across the trigger gap with the help of a switching insulated gate bipolar transistor. With the breakdown of the trigger gap, plasma is generated, which is injected into the main gap. The trigger pin is placed axisymmetric to the main spark gap in the cathode. The main discharge channel of the spark gap has 0.6 mm space between two electrodes, which is charged to 1000 V. When the spark gap is triggered, the discharge current has a peak value of 6.1 kA with a quarter cycle time period of 0.97 µs. The four-electrode spark gap switch results are compared with those of a three-electrode trigatron switch, which has the peak current of 6 kA with 1.01 µs as quarter-cycle time period. Four similar four-electrode spark gap switches are triggered with the same scheme and synchronized within 10 ns as peak values of currents with jitter as less than 5 ns.
Predicting regime changes and durations in Lorenz’s atmospheric convection model
Authors: Brugnago Eduardo L. , Gallas Jason A. C. , Beims Marcus W.
Published: October 2020

We show that a characteristic alignment between Lyapunov vectors can be used to predict regime changes as well as regime duration in the classical Lorenz model of atmospheric convection. By combining Lyapunov vector alignment with maxima in the local expansion of bred vectors, we obtain an effective and competitive method to significantly decrease errors in the prediction of regime durations.
Statistical mechanics with non-integrable topological constraints: Self-organization in knotted phase space
Authors: Sato Naoki
Published: October 2020

The object of this study is the statistical mechanics of dynamical systems lacking a Hamiltonian structure due to the presence of non-integrable topological constraints that limit the accessible regions of the phase space. Focusing on the simplest three dimensional case, we develop a procedure (Poissonization) that assigns to any three dimensional non-Hamiltonian system an equivalent four dimensional Hamiltonian system endowed with a proper time. The statistical distribution is then constructed in the recovered four dimensional canonical phase space. Projecting in the original reference frame, we show that the statistical distribution departs from standard Maxwell–Boltzmann statistics. The deviation is a function of the knottedness of the phase space, which is measured by the helicity density of the topological constraint. The theory is then generalized to a class of non-Hamiltonian systems in higher dimensions.
The role of thermal history on spontaneous polarization and phase transitions of amorphous solid water films studied by contact potential difference measurements
Authors: Sagi Roey , Akerman Michelle , Ramakrishnan Sujith , Asscher Micha
Published: October 2020

Monitoring thermal processes occurring in molecular films on surfaces can provide insights into physical events such as morphology changes and phase transitions. Here, we demonstrate that temperature-programmed contact potential difference (TP-∆CPD) measurements employed by a Kelvin probe under ultrahigh vacuum conditions and their temperature derivative can track films’ restructure and crystallization occurring in amorphous solid water (ASW) at temperatures well below the onset of film desorption. The effects of growth temperature and films’ thickness on the spontaneous polarization that develops within ASW films grown at 33 K–120 K on top of a Ru(0001) substrate are reported. Electric fields of ∼106 V/m are developed within the ASW films despite low average levels of molecular dipole alignment (<0.01%) normal to the substrate plane. Upon annealing, an irreversible morphology-dependent depolarization has been recorded, indicating that the ASW films keep a “memory” of their thermal history. We demonstrate that TP-∆CPD measurements can track the collapse of the porous structure at temperatures above the growth and the ASW-ice Ic and ASW-ice Ih transitions at 131 K and 157 K, respectively. These observations have interesting implications for physical and chemical processes that take place at the interstellar medium such as planetary formation and photon- and electron-induced synthesis of new molecules.
Evaluating diffusion and the thermodynamic factor for binary ionic mixtures
Authors: Rosenberger David , Lubbers Nicholas , Germann Timothy C.
Published: October 2020

Molecular dynamics (MD) simulations are a powerful tool for the calculation of transport properties in mixtures. Not only are MD simulations capable of treating multicomponent systems, they are also applicable over a wide range of temperatures and densities. In plasma physics, this is particularly important for applications such as inertial confinement fusion. While many studies have focused on the effect of plasma coupling on transport properties, here we focus on the effects of mixing. We compute the thermodynamic factor, a measure of ideal/non-ideal mixing, for three binary ionic mixtures. We consider mixtures of hydrogen and carbon, hydrogen and argon, and argon and carbon, each at 500 randomly generated state points in the warm dense matter and plasma regimes. The calculated thermodynamic factors indicate different mixing behavior across phase space, which can significantly affect the corresponding mutual diffusion coefficients. As MD simulations are still computationally expensive, we apply modern data science tools to predict the thermodynamic factor over a large phase space. Further, we propose a more accurate approximation to the mutual diffusion coefficient than the commonly applied Darken relation.
Integral transforms between tomogram and quasi-probability functions based on quantizer-dequantizer operators formalism
Authors: Man’ko V. I. , Markovich L. A.
Published: October 2020

An application of a quantizer–dequantizer method as a unifying description for representations of states in quantum mechanics is considered. Well-known quasi-distributions and tomograms are rewritten in terms of the dequantizer and quantizer operators. Using this description of the tomographic probability function and its symbol, we construct the invertible integral transforms between the tomogram and the quasi-probability distributions such as Wigner, Kirkwood–Rihaczek, Choi–Williams, P- and Q-functions, and others.
Impact of single and double oxygen vacancies on electronic transport in Fe/MgO/Fe magnetic tunnel junctions
Authors: Taudul Beata , Bowen M. , Alouani M.
Published: October 2020

The combination of a low tunneling barrier height and a large tunneling magnetoresistance (TMR) ratio in MgO-class magnetic tunnel junctions (MTJs) has enabled next-generation information storage and bio-inspired computing solutions thanks to the spin transfer torque effect. Recent literature has proposed that this synergistic combination arises from the electronic properties of oxygen vacancies. To explicitly understand their impact on spin-polarized transport, we have computed the electronic and transport properties of single (F centers) and paired (M centers) oxygen vacancies using density functional theory and the projector augmented wave method. These point defects can generate energy level positions of 0.4 eV with respect to the Fermi level for FeCo electrodes irrespective of the defect’s spatial position within the MgO barrier and of the orientation of the M center. These defects promote a strong decrease in the conductance of the spin up channel in the MTJ’s parallel magnetic state that mainly accounts for an order-of-magnitude drop in TMR from ≈10000% in the ideal case toward values more in line with experiment. When placed in the middle layer of the MgO barrier, the F center introduces additional P ↑ transmission away from the Γ point. This scattering lowers TMR to 145%. In contrast, the M center merely broadens this transmission around Γ, thereby boosting TMR to 315%. Rotating a M center so as to partly point along the transmission direction sharpens transmission around Γ, further increasing TMR to 1423%. When these defects are placed at the MTJ interface, the transmission and ensuing TMR, which reaches ≈4000%, suggest that such junctions behave as an ideal MTJ only with a much lower TMR. Our results, thus, theoretically reconcile the concurrent observations of high TMR and low barrier heights in line with experimental preparation techniques such as post-deposition oxidation of metallic Mg, which can generate oxygen vacancies at the lower MTJ interface, and annealing which can promote M centers over F centers. Our theory is also in line with an origin of perpendicular magnetic anisotropy in terms of oxygen vacancies at MTJ interfaces. The effective size of these vacancies sets a limit for both the barrier thickness, in line with experiment, as well as for the MTJ’s lateral dimension. Our work provides a much-needed theoretical basis to move beyond the mostly unsuspected, fortuitous defect engineering of spintronic performance that has, thus, far propelled MgO-based spintronics and its applications.
Modulated and spiral surface patterns on deformable lipid vesicles
Authors: Luo Yongtian , Maibaum Lutz
Published: October 2020

We investigate the behavior of two-dimensional systems that exhibit a transition between homogeneous and spatially inhomogeneous phases, which have spherical topology, and whose mechanical properties depend on the local value of the order parameter. One example of such a system is multicomponent lipid bilayer vesicles, which serve as a model to study cellular membranes. Under certain conditions, such bilayers separate into coexisting liquid-ordered and liquid-disordered regions. When arranged into the shape of small vesicles, this phase coexistence can result in spatial patterns that are more complex than the basic two-domain configuration encountered in typical bulk systems. The difference in bending rigidity between the liquid-ordered and liquid-disordered regions couples the shape of the vesicle to the local composition. We show that this interplay gives rise to a rich phase diagram that includes homogeneous, separated, and axisymmetric modulated phases that are divided by regions of spiral patterns in the surface morphology.
Hysteresis of aeroacoustic sound generation in the articulation of [s]
Authors: Yoshinaga Tsukasa , Nozaki Kazunori , Iida Akiyoshi
Published: October 2020

A fricative consonant (e.g., [s]) is known to be pronounced by a turbulent jet flow inside the oral cavity. In this study, the effects of tongue motion on the aeroacoustic sound generation during the articulation of [s] were investigated through the large eddy simulation of compressible flow using a simplified vocal tract model. The walls of the simplified model were expressed using a volume penalization approach as an immersed boundary method, and the tongue geometry was ascended and descended from the position of /u/ to /s/ with tongue speeds of 40 mm/s, 60 mm/s, and 80 mm/s. The simulated acoustic pressure at a far-field sampling point was compared with previous experimental measurements, and the acoustic characteristics of the simulated sound reasonably agreed with those of the experiment. The overall acoustic amplitudes increased and decreased in accordance with tongue ascent and descent, and these transitions in amplitudes were almost the same for the different tongue speeds. Meanwhile, we found a hysteresis effect on the overall acoustic amplitudes between tongue ascent and tongue descent. This hysteresis was caused by the larger velocity fluctuations and vortices near the upper and lower teeth during tongue descent, and the results indicated that these flow differences occurred owing to the inertia of the turbulent flow structures and the aerodynamic pressures over the constriction of the vocal tract. This study suggests that these phenomena cause a delay in the sound generation of [s].
First-principles study of Pd-alloyed Cu(111) surface in hydrogen atmosphere at realistic temperatures
Authors: Han Zhong-Kang , Sarker Debalaya , Troppenz Maria , Rigamonti Santiago , Draxl Claudia , Saidi Wissam A. , Levchenko Sergey V.
Published: October 2020

Alloying is a well-established and versatile method to modify and tune properties of functional materials. Alloy properties depend crucially on the spatial distribution of the alloying elements. In particular, in heterogeneous catalysis, the distribution of guest metal atoms at the catalytic surface has a dramatic effect on its chemical properties. Combining a cluster-expansion model, parameterized with density-functional theory calculations, with Monte Carlo sampling, we describe the distribution and segregation of Pd atoms on the Pd-alloyed Cu(111) surface as a function of H coverage at realistic temperatures. We find that, while in vacuum Pd enriches the near-surface region of Pd/Cu(111), Pd segregates to the bulk layers away from the surface under increasing H coverage. These findings are crucial for designing metal-alloy catalysts with dynamically changing properties.
Benchmarking polarizable and non-polarizable force fields for Ca2+–peptides against a comprehensive QM dataset
Authors: Amin Kazi S. , Hu Xiaojuan , Salahub Dennis R. , Baldauf Carsten , Lim Carmay , Noskov Sergei
Published: October 2020

Explicit description of atomic polarizability is critical for the accurate treatment of inter-molecular interactions by force fields (FFs) in molecular dynamics (MD) simulations aiming to investigate complex electrostatic environments such as metal-binding sites of metalloproteins. Several models exist to describe key monovalent and divalent cations interacting with proteins. Many of these models have been developed from ion–amino-acid interactions and/or aqueous-phase data on cation solvation. The transferability of these models to cation–protein interactions remains uncertain. Herein, we assess the accuracy of existing FFs by their abilities to reproduce hierarchies of thousands of Ca2+–dipeptide interaction energies based on density-functional theory calculations. We find that the Drude polarizable FF, prior to any parameterization, better approximates the QM interaction energies than any of the non-polarizable FFs. Nevertheless, it required improvement in order to address polarization catastrophes where, at short Ca2+–carboxylate distances, the Drude particle of oxygen overlaps with the divalent cation. To ameliorate this, we identified those conformational properties that produced the poorest prediction of interaction energies to reduce the parameter space for optimization. We then optimized the selected cation–peptide parameters using Boltzmann-weighted fitting and evaluated the resulting parameters in MD simulations of the N-lobe of calmodulin. We also parameterized and evaluated the CTPOL FF, which incorporates charge-transfer and polarization effects in additive FFs. This work shows how QM-driven parameter development, followed by testing in condensed-phase simulations, may yield FFs that can accurately capture the structure and dynamics of ion–protein interactions.
The effect of ion irradiation on dephasing of coherent optical phonons in GaP
Authors: Ichikawa Takuto , Saito Yuta , Hase Muneaki
Published: October 2020

The dephasing of coherent longitudinal optical (LO) phonons in ion-irradiated GaP has been investigated with a femtosecond pump-probe technique based on electro-optic sampling. The dephasing time of the coherent LO phonon is found to be dramatically prolonged by the introduction of a small amount of defects by means of Ga-ion irradiation. The maximum dephasing time observed at room temperature is 9.1 ps at a Ga+ ion dose of 1013/cm2, which is significantly longer than the value of 8.3 ps for GaP before ion irradiation. The longer dephasing time is explained in terms of the suppression of electron-LO-phonon scattering by the presence of defect-induced deep levels.
Study on N2–SF6 mixtures breakdown characteristics at the gas/dielectric interface of microwave window
Authors: Zhang Jianwei , Jiang Ming , Luo Wei , Wang Hongguang , Li Yongdong , Liu Chunliang
Published: October 2020

The high power microwave window breakdown characteristics of N2–SF6 mixtures are investigated with 3D particle-in-cell and Monte Carlo collision simulation. The space and density distributions of electrons and ions are obtained. The results show that the threshold of breakdown increases with the ratio of SF6 when E/P is large. However, when E/P is small, the threshold of breakdown in 70% of SF6 and 30% of N2 is greater than that of pure SF6. This phenomenon is also observed in experiments. The theory analyses show that the energy loss of electrons is mainly caused by excitation collisions with N2 when the average energy of electrons Te is less than 6 eV and is dominated by excitation and ionization collisions with SF6 when Te is greater than 6 eV. When E/P is small, the proportion of low energy electrons is large and Te increases with the ratio of SF6. Therefore, the effective ionization rate first decreases and then increases as the ratio of SF6 increases. Thus, the optimal ratio for improving the insulation properties is 60%–80% SF6 when E/P is small. When E/P is large, the proportion of high energy electrons increases. Therefore, the effective ionization rate and density of electrons decrease as the ratio of SF6 increases. The maximum threshold of breakdown occurs when the ratio of SF6 is 100%.
Processing advances in liquid crystal elastomers provide a path to
biomedical applications
Authors: Ambulo Cedric P. , Tasmim Seelay , Wang Suitu , Abdelrahman Mustafa K. , Zimmern Philippe E. , Ware Taylor H.
Published: October 2020

Liquid crystal elastomers (LCEs) are a class of stimuli-responsive polymers that undergo reversible shape-change in response to environmental changes. The shape change of LCEs can be programmed during processing by orienting the liquid crystal phase prior to crosslinking. The suite of processing techniques that has been developed has resulted in a myriad of LCEs with different shape-changing behavior and mechanical properties. Aligning LCEs via mechanical straining yields large uniaxial actuators capable of a moderate force output. Magnetic fields are utilized to control the alignment within LCE microstructures. The generation of out-of-plane deformations such as bending, twisting, and coning is enabled by surface alignment techniques within thin films. 4D printing processes have emerged that enable the fabrication of centimeter-scale, 3D LCE structures with a complex alignment. The processing technique also determines, to a large extent, the potential applications of the LCE. For example, 4D printing enables the fabrication of LCE actuators capable of replicating the forces generated by human muscles. Employing surface alignment techniques, LCE films can be designed for use as coatings or as substrates for stretchable electronics. The growth of new processes and strategies opens and strengthens the path for LCEs to be applicable within biomedical device designs.
Toroidal modeling of runaway electron loss due to 3-D fields in DIII-D and COMPASS
Authors: Liu Yueqiang , Paz-Soldan C. , Macusova E. , Markovic T. , Ficker O. , Parks P. B. , Kim C. C. , Lao L. L. , Li L.
Published: October 2020

The 3-D field induced relativistic runaway electron (RE) loss has been simulated for DIII-D and COMPASS plasmas, utilizing the MARS-F code incorporated with the recently developed and updated RE orbit module (REORBIT). Modeling shows effectively 100% loss of a post-disruption, high-current runaway beam in DIII-D due to the 1 kG level of magnetic field perturbation produced by a fast growing n = 1 resistive kink instability. This complete RE loss is shown to be independent of the particle energy or the initial location of particles in the configuration space. Applied resonant magnetic perturbation (RMP) fields from in-vessel coils are not effective for RE beam mitigation in DIII-D but do produce finite (>10%) RE loss in COMPASS post-disruption plasmas, consistent with experimental observations in the above two devices. The major reasons for this difference in RE control by RMP between these two devices are (i) the coil proximity to the RE beam and (ii) the effective coil current scaling vs the machine size and the toroidal magnetic field. In the modeling, the lost REs due to 3-D fields deposit onto the limiting surfaces of the devices. Distributions of the lost REs to the limiting surface show a poloidally peaked profile near the high-field-side in both DIII-D and COMPASS, covering about 100° poloidal angle. A higher perturbation field level and/or higher particle energy also result in REs being lost to the low-field-side of the limiting surface of these two devices, increasing the effective wetted area.
Formation and stability of small polarons at the lithium-terminated Li4Ti5O12 (LTO) (111) surface
Authors: Kick Matthias , Scheurer Christoph , Oberhofer Harald
Published: October 2020

Zero strain insertion, high cycling stability, and a stable charge/discharge plateau are promising properties rendering Lithium Titanium Oxide (LTO) a possible candidate for an anode material in solid state Li ion batteries. However, the use of pristine LTO in batteries is rather limited due to its electronically insulating nature. In contrast, reduced LTO shows an electronic conductivity several orders of magnitude higher. Studying bulk reduced LTO, we could show recently that the formation of polaronic states can play a major role in explaining this improved conductivity. In this work, we extend our study toward the lithium-terminated LTO (111) surface. We investigate the formation of polarons by applying Hubbard-corrected density functional theory. Analyzing their relative stabilities reveals that positions with Li ions close by have the highest stability among the different localization patterns.
Binding and excitations in SixHy molecular systems using quantum Monte Carlo
Authors: Wang Guangming , Annaberdiyev Abdulgani , Mitas Lubos
Published: October 2020

We present high-accuracy correlated calculations of small SixHy molecular systems in both the ground and excited states. We employ quantum Monte Carlo (QMC) together with a variety of many-body wave function approaches based on basis set expansions. The calculations are carried out in a valence-only framework using recently derived correlation consistent effective core potentials. Our primary goal is to understand the fixed-node diffusion QMC errors in both the ground and excited states with single-reference trial wave functions. Using a combination of methods, we demonstrate the very high accuracy of the QMC atomization energies being within ≈0.07 eV or better when compared with essentially exact results. By employing proper choices for trial wave functions, we have found that the fixed-node QMC biases for total energies are remarkably uniform ranging between 1% and 3.5% with absolute values at most ≈0.2 eV across the systems and several types of excitations such as singlets and triplets as well as low-lying and Rydberg-like states. Our results further corroborate that Si systems, and presumably also related main group IV and V elements of the periodic table (Ge, Sn, etc), exhibit some of the lowest fixed-node biases found in valence-only electronic structure QMC calculations.
Simultaneous determination of multiple transport properties over a wide range of temperatures and pressures from the analysis of non-equilibrium fluctuations by the shadowgraph method
Authors: Wu W. , Jander J. H. , Rausch M. H. , Fröba A. P. , Giraudet C.
Published: October 2020

The present work demonstrates that by the analysis of the dynamics of non-equilibrium fluctuations using the shadowgraph method, the thermal diffusivity, the Fick diffusion coefficient, the kinematic viscosity, and the Soret coefficient of a binary mixture can be determined from a single thermodiffusion experiment. The study was performed for a mixture consisting of equal masses of 1,2,3,4-tetrahydronaphthalene and n-dodecane in a newly developed shadowgraph apparatus at temperatures up to 373 K and pressures up to 40 MPa. The obtained results are mainly discussed in the light of their uncertainties at varying thermodynamic states for evaluating the benefits, drawbacks, and potentials of the apparatus. The Fick diffusion coefficient and the thermal diffusivity obtained with average expanded uncertainties of 2.8% and 6.6% agree with literature data and measurements for the same mixture taken by heterodyne dynamic light scattering. Current limitations of the method are reflected by the distinctly larger uncertainties of the kinematic viscosity and the Soret coefficient. Corresponding reasons and potential measures to overcome the limitations are discussed.
MOCVD growth of β-phase (AlxGa1−x)2O3 on (2¯01) β-Ga2O3 substrates
Authors: Bhuiyan A F M Anhar Uddin , Feng Zixuan , Johnson Jared M. , Huang Hsien-Lien , Hwang Jinwoo , Zhao Hongping
Published: October 2020

β-(AlxGa1−x)2O3 thin films are grown on (2¯01) β-Ga2O3 substrates via metal organic chemical vapor deposition to investigate the solubility of Al in β-phase Ga2O3. The x-ray diffraction (XRD) spectra reveal crystalline quality (2¯01) β-(AlxGa1−x)2O3 thin films with Al compositions up to 48%. The Al compositions are further confirmed by high resolution x-ray spectroscopy measurements and energy-dispersive x-ray spectra (EDS) mapping. The bandgap energies extracted from XPS spectra range between 5.20 ± 0.06 eV and 5.72 ± 0.08 eV for x = 21%–48%. The surface morphology evaluated by both scanning electron microscopy and atomic force microscopy shows elongated features with granules along the [010] direction, which are suppressed with the increasing Al content. A systematic growth study through tuning growth parameters indicates that the chamber pressure plays an important role in both surface morphology and Al incorporation. Material characterization via high resolution scanning transmission electron microscopy and STEM-EDS reveals Al fluctuations in the sample with the 48% Al composition. Atomic resolution STEM imaging and XRD spectra for (2¯01) β-(AlxGa1−x)2O3/Ga2O3 superlattice structures confirm that the periodicity of the β-(AlxGa1−x)2O3/Ga2O3 sub-layers is well maintained with high-Al compositions.
N4Mg6M (M = Li, Na, K) superalkalis for CO2 activation
Authors: Sikorska Celina , Gaston Nicola
Published: October 2020

Superatoms have exciting properties, including diverse functionalization, redox activity, and magnetic ordering, so the resulting cluster-assembled solids hold the promise of high tunability, atomic precision, and robust architectures. By utilizing adamantane-like clusters as building blocks, a new class of superatoms N4Mg6M (M = Li, Na, K) is proposed here. The studied superalkalis feature low adiabatic ionization energies, an antibonding character in the interactions between magnesium and nitrogen atoms, and highly delocalized highest occupied molecular orbital (HOMO). Consequently, the N4Mg6M superalkalis might easily lose their HOMO electrons when interacting with superhalogen electrophiles to form stable superatom [superalkali]+[superhalogen]− compounds. Moreover, the studied superalkalis interact strongly with carbon dioxide, and the resulting N4Mg6M/CO2 systems represent two strongly interacting ionic fragments (i.e., N4Mg6M+ and CO2−). In turn, the electron affinity of the N2 molecule (of −1.8 eV) is substantially lower than that observed for carbon dioxide (EA = −0.6 eV) and consequently, the N2 was found to form the weakly bound [N4Mg6M][N2] complex rather than the desired ionic [N4Mg6M]+[N2]− product. Thus, the N4Mg6M superalkalis have high selectivity over N2 when it comes to CO2 reduction and also are themselves stable. We believe that the results described within this paper will be useful for understanding CO2 activation, which is the first step for producing fuels from CO2. Moreover, we demonstrate that designing novel superatomic systems and exploring their physicochemical features might be used to create desirable functional materials.
Femtosecond photocurrents at the FeRh/Pt interface
Authors: Medapalli R. , Li G. , Patel Sheena K. K. , Mikhaylovskiy R. V. , Rasing Th. , Kimel A. V. , Fullerton E. E.
Published: October 2020

Femtosecond laser excitations of FeRh/Pt bilayers launch an ultrafast pulse of electric photocurrents in the Pt-layer and subsequently result in the emission of electromagnetic radiation in the THz spectral range. Analysis of the THz emission as a function of the polarization of the femtosecond laser pulse, external magnetic field, sample temperature, and sample orientation shows that the photocurrent can emerge due to vertical spin pumping and photo-induced inverse spin–orbit torque at the FeRh/Pt interface. The vertical spin pumping from FeRh into Pt does not depend on the polarization of light and originates from ultrafast laser-induced demagnetization of the ferromagnetic phase of FeRh. The photo-induced inverse spin–orbit torque at the FeRh/Pt interface can be described in terms of a helicity-dependent effect of circularly polarized light on the magnetization of the ferromagnetic FeRh and the subsequent generation of a photocurrent.
Donors and polaronic absorption in rutile TiO2 single crystals
Authors: Weiser Philip Michael , Zimmermann Christian , Bonkerud Julie , Vines Lasse , Monakhov Eduard V.
Published: October 2020

We have used a combination of optical absorption and electrical conductivity measurements to study the effect of the main donor on small polarons in rutile TiO2 single crystals rendered n-type conductive by hydrogenation or doping with Nb. The electrical conductivity measured at 295 K for hydrogenated samples shows a clear correlation with the interstitial hydrogen (Hi) concentration, which is consistent with reports that Hi is the main shallow donor in rutile TiO2. Conductive samples exhibit two distinct optical absorption bands in the IR spectral region, at ω1 = 6500 cm−1 (∼0.8 eV) and ω2 = 3100 cm−1 (∼0.4 eV), which are present in both hydrogen-rich and Nb-doped samples. The intensities of the absorption bands are proportional to the electrical conductivity, and they exhibit an Arrhenius-like temperature dependence for temperatures between 25–50 K and 50–100 K for H-doped and Nb-doped samples, respectively. The thermal activation energies (EAs) for the absorption bands depend strongly on the main donor: ω2 exhibits EA(H) and EA(Nb) of ∼4 and ∼10 meV, respectively, whereas ω1 shows EA(H) and EA(Nb) of ∼1 and ∼2 meV, respectively. The combination of temperature-dependent data for the optical absorption bands and interstitial deuterium (Di)-small polaron vibrational lines support a model where the thermal activation is associated with the reconfiguration of small polarons involving Ti sites far away from the donor. The thermal activation of the optical absorption bands gives us insight into the dynamics of donor-dependent small polaron reconfiguration in rutile TiO2.
What is needed to restore native fishes in Australia’s Murray–Darling Basin?
Authors: Koehn John D. , Balcombe Stephen R. , Baumgartner Lee J. , Bice Christopher M. , Burndred Kate , Ellis Iain , Koster Wayne M. , Lintermans Mark , Pearce Luke , Sharpe Clayton , Stuart Ivor , Todd Charles R.
Published: October 2020

The Murray–Darling Basin (MDB) is Australia’s food bowl, contributing 40% of agricultural production and supporting a population of over 4 million people. Historically, the MDB supported a unique native fish community with significant cultural, subsistence, recreational, commercial and ecological values. Approximately one-quarter of the MDB’s native species are endemic. Changes to river flows and habitats have led to a >90% decline in native fish populations over the past 150 years, with almost half the species now of conservation concern. Commercial fisheries have collapsed, and important traditional cultural practices of First Nations People have been weakened. The past 20 years have seen significant advances in the scientific understanding of native fish ecology, the effects of human-related activities and the recovery measures needed. The science is well established, and some robust restoration-enabling policies have been initiated to underpin actions. What is now required is the political vision and commitment to support investment to drive long-term recovery. We present a summary of 30 priority activities urgently needed to restore MDB native fishes.
Organic carbon fractions in temperate mangrove and saltmarsh soils
Authors: Wong V. N. L. , Reef R. E. , Chan C. , Goldsmith K. S.
Published: October 2020

Coastal wetlands, such as mangrove and saltmarsh environments, can store significant amounts of soil organic carbon (SOC); however, most studies focus on tropical and subtropical environments. We assessed SOC stocks and fractions in temperate mangrove (two sites) and saltmarsh (sites SM1, SM2 and SM3) environments in southern Australia. The SOC fractions were separated according to particulate organic carbon (POC), humic carbon (HC) and recalcitrant carbon (RC) by size fractionation. Saltmarsh sites generally had the highest SOC content (up to 12.4% SOC). The POC fraction was the highest at the surface in the saltmarsh site and decreased relative to the HC and RC fractions with depth. Conversely, the proportion of POC at the mangrove sites did not decrease with depth, forming up to 76% of the SOC. The vertical displacement of soil of up to 5.8 mm year–1 at the saltmarsh sites, measured using root ingrowth bags, suggest significant contributions of POC via root materials. Retention of these POC inputs are likely to be related to waterlogging, which decreases decomposition rates – with much lower soil moisture content at SM1, where the lowest POC content occurred below the surface, compared with SM2 and SM3.
One health study designs.
Authors: Schelling Esther , Hattendorf Jan
Published: October 2020

This chapter focused on population-based quantitative One Health study designs with emphasis on planning of field studies. Selected examples on joint surveys, then on practical information for planning a field study design were presented. This chapter concludes on the advantages of One Health study designs as well as on the possible constraints for their implementation given that there are only a few One Health studies to date.
A legal framework of one health: the human-animal relationship.
Authors: Wettlaufer Lenke , Hafner Felix , Zinsstag Jakob , Farnese Patricia L.
Published: October 2020

This chapter provides an introduction to the legal framework of One Health. It begins with an overview of national Swiss provisions concerning the human-animal relationship in constitutional law, private law and animal welfare law including animal disease law. The chapter then introduces European Union (EU) regulations, World Trade Organization (WTO) agreements, World Organisation for Animal Health (OIE) recommendations and World Health Organization (WHO) regulations. This chapter concludes by emphasizing that the greater importance is to attach animal welfare issues as part of the One Health concept wherein the One Health approach is a compelling reason to strengthen animal welfare laws with the purpose of enhancing both animal and, consequently, human health.
A one health perspective for integrated human and animal sanitation, nutrient recycling and climate change.
Authors: Nguyen-Viet Hung , Cissé Guéladio , Pham-Duc Phuc , Nguyen Vi , Tanner Marcel , Odermatt Peter , Vu-Van Tu , Minh Hoang Van , Zurbrügg Christian , Schelling Esther , Zinsstag Jakob
Published: October 2020

In this chapter, the authors present their experiences in developing a conceptual framework for integrated health and environmental assessment, combining health status, physical, socio-economic and cultural environments to improve health and minimize environmental impact. Highlights focused on how the framework was used to manage human and animal excreta in Vietnam and the added value offered from an integrated assessment.
The spiritual dimension of health.
Authors: Fries Thomas , Cooke Karin Tschanz , Berger Mónica González
Published: October 2020

This chapter describes the concept of spirituality and religion and their role in human health.
Mafeje: scholar–activist with noble convictions
Authors: Jacobs Peter T.
Published: October 2020

This critical review of an edited volume of Archie Mafeje’s writings closes gaps in what is known about his political upbringing, his scientific methodology and posthumous intellectual influence. Trained in the radical political tradition of the Unity Movement of South Africa, Mafeje was a celebrated social theorist, broke with liberal functionalism in social anthropology and wrote prolifically. This important volume is silent on standout questions, such as: why did Mafeje, the mature scholar–activist, dissociate himself from practical politics after relocating from Cairo to Pretoria, given the crisis of the radical left in South Africa? To what extent did Mafeje wield his mastery of dialectical logic not only to interpret the world but actively change it? What was Mafeje’s orientation toward agrarian transitions beyond capitalism in countries like South Africa? In response to these thematic questions, this essay synthesises insights from relevant chapters.
Chromium, a promising cathode candidate for homogeneous arc erosion in air
Authors: Guan Weimian , Yuan Jie , Lv Hao , Zhu Tao , Fang Youtong , Liu Jiabin , Wang Hongtao , Tang Zhigong , Yang Wei
Published: October 2020

Cathode erosion hinders the development of high-power arc heaters, and the inhomogeneous erosion of the copper cathode results in catastrophic failures. In this work, the arc erosion behavior of a chromium cathode was investigated compared with copper. The former was relatively homogeneous with shallow erosion pits. The eroded microstructure suggests that the surface chromic oxide layer could suppress the formation of deep craters. The maximum erosion depth and the erosion rate of chromium were lower than those of copper. The single erosion pits on chromium gradually extended and disappeared, suggesting a reduction in the input energy flux density. The underlying mechanism for the homogeneous erosion behavior of the chromium cathode was proposed. The homogeneous erosion behavior of the chromium cathode makes it a promising candidate for high-power arc heaters.