bluuebunny/crossref_metadata_2025 huggingface dataset:
Unicompartmental Knee Arthroplasty in Octogenarians versus Younger Patients: A Comparison of 30-Day Outcomes
Authors: Kavanagh Michael D. , Abola Matthew V. , Tanenbaum Joseph E. , Knapik Derrick M. , Fitzgerald Steven J. , Wera Glenn D.
Published: August 2020

As the United States' octogenarian population (persons 80–89 years of age) continues to grow, understanding the risk profile of surgical procedures in elderly patients becomes increasingly important. The purpose of this study was to compare 30-day outcomes following unicompartmental knee arthroplasty (UKA) in octogenarians with those in younger patients. The American College of Surgeons National Surgical Quality Improvement Program database was queried. All patients, aged 60 to 89 years, who underwent UKA from 2005 to 2016 were included. Patients were stratified by age: 60 to 69 (Group 1), 70 to 79 (Group 2), and 80 to 89 years (Group 3). Multivariate regression models were estimated for the outcomes of hospital length of stay (LOS), nonhome discharge, morbidity, reoperation, and readmission within 30 days following UKA. A total of 5,352 patients met inclusion criteria. Group 1 status was associated with a 0.41-day shorter average adjusted LOS (99.5% confidence interval [CI]: 0.67–0.16 days shorter, p < 0.001) relative to Group 3. Group 2 status was not associated with a significantly shorter LOS compared with Group 3. Both Group 1 (odds ratio [OR] = 0.15, 99.5% CI: 0.10–0.23) and Group 2 (OR = 0.33, 99.5% CI: 0.22–0.49) demonstrated significantly lower adjusted odds of nonhome discharge following UKA compared with Group 3. There was no significant difference in adjusted odds of 30-day morbidity, readmission, or reoperation when comparing Group 3 patients with Group 1 or Group 2. While differences in LOS and nonhome discharge were seen, octogenarian status was not associated with increased adjusted odds of 30-day morbidity, readmission, or reoperation. Factors other than age may better predict postoperative complications following UKA.
Meniscus Graft Augmentation for a Midsubstance Tear of the Medial Collateral Ligament during Total Knee Arthroplasty
Authors: Sun Changjiao , Rong Wei , Du Ruiyong , Wu Sha , Liu Pu , Zhang Wei , Cai Xu
Published: August 2020

Abstracts

Multiple surgical techniques exist to repair iatrogenic medial collateral ligament (MCL) injury during total knee arthroplasty (TKA). The objective of the study is to confirm the clinical effectiveness of meniscus transfer for treatment of iatrogenic MCL midsubstance transection in which remaining MCL is of poor quality, and there is a persistent gap between both ligament ends during TKA. From January 2015 to November 2019, we treated 11 patients with MCL injuries of 882 primary TKAs by meniscus transfer. Another 24 primary TKAs were recruited as a control group. The two groups of patients were comparable for age, gender, body mass index (BMI), Knee Society scoring (KSS), knee function score (KFS), and type of prosthesis comparison without significant difference (p > 0.05). We reviewed the patient's stability, as well as objective measures such as KSS and KFS scores, physical examinations, and radiographs. No patient of either group reported impaired wound healing, joint instability on physical examination, pain, radiographic changes, signs of loosening, and other complications. At the final follow-up, there was no significant difference in terms of KSS (p = 0.780) and KFS (p = 0.612) between the injury group and control group at last follow-up. X-ray image review showed no prosthesis loosening or subsidence for both groups. Based on these results, we are cautiously optimistic that midsubstance transections in which the quality of remaining tendon is weak, there is suspicion of stretching, or there is a persistent gap between both ligament ends that can be reconstructed with meniscus autograft transfer augmentation and an unconstrained implant.
Total Knee Arthroplasty after Previous Ipsilateral Hip Arthroplasty Showed Lower Clinical Outcomes and Higher Leg Length Discrepancy Perception
Authors: Lee Han-Jun , Kim Seong Hwan , Pujol Nicolas , Park Yong-Beom
Published: August 2020

The purpose of this study is to compare perception of leg length discrepancy (LLD) and clinical results of total knee arthroplasties (TKA) in patients with or without previous ipsilateral hip arthroplasty. Between 2008 and 2015, navigation-assisted TKA was performed in 43 patients with previous hip arthroplasty after hip fracture. After 1:3 propensity score matching was performed, 108 patients of primary navigation-assisted TKA (group 1) and 36 patients with hip arthroplasty (group 2) were included. Knee Society (KS) scores, Western Ontario and McMaster Universities Index (WOMAC) scores, and patients' satisfaction including perception of LLD were evaluated. Radiographic evaluation included mechanical axis, component position, and LLD. Logistic regression analysis was performed to find the factors that affect the clinical outcomes. No significant differences in radiologic and clinical evaluations, except for KS function score, patient's satisfaction and LLD (p< 0.001), were detected between the groups. LLD and its perception were significantly higher in group 2 (1.8 ± 3.4 mm in group 1 and 9.7 ± 4.1 mm in group 2, p = 0.000). Risk factors for the low KS function score were found as LLD (odds ratio [OR]: 1.403, p = 0.008) and previous hip arthroplasty itself (OR: 15.755, p = 0.002), but much higher OR was found in previous hip arthroplasty. Although the outcomes of TKA in patients with ipsilateral hip arthroplasty are comparable to those of primary TKA, LLD was high and patient's satisfaction and functional outcomes were low in patients with previous ipsilateral hip arthroplasty. Care should be taken when considering TKA in patients with previous hip arthroplasty. This is a Level III, case control study.
The 4S-AF Scheme (Stroke Risk; Symptoms; Severity of Burden; Substrate): A Novel Approach to In-Depth Characterization (Rather than Classification) of Atrial Fibrillation
Authors: Potpara Tatjana S. , Lip Gregory Y. H. , Blomstrom-Lundqvist Carina , Boriani Giuseppe , Van Gelder Isabelle C. , Heidbuchel Hein , Hindricks Gerhard , Camm Alan John
Published: August 2020

Atrial fibrillation (AF) is a complex condition requiring holistic management with multiple treatment decisions about optimal thromboprophylaxis, symptom control (and prevention of AF progression), and identification and management of concomitant cardiovascular risk factors and comorbidity. Sometimes the information needed for treatment decisions is incomplete, as available classifications of AF mostly address a single domain of AF (or patient)-related characteristics. The most widely used classification of AF based on AF episode duration and temporal patterns (that is, the classification to first-diagnosed, paroxysmal, persistent/long-standing persistent, and permanent AF) has contributed to a better understanding of AF prevention and treatment but its limitations and the need for a multidimensional AF classification have been recognized as more complex treatment options became available. We propose a paradigm shift from classification toward a structured characterization of AF, addressing specific domains having treatment and prognostic implications to become a standard in clinical practice, thus aiming to streamline the assessment of AF patients at all health care levels facilitating communication among physicians, treatment decision-making, and optimal risk evaluation and management of AF patients. Specifically, we propose the 4S-AF structured pathophysiology-based characterization (rather than classification) scheme that includes four AF- and patient-related domains—Stroke risk, Symptoms, Severity of AF burden, and Substrate severity—and provide a hypothetical model for the use of 4S-AF characterization scheme to aid treatment decision making concerning the management of patients with AF in clinical practice.
An improved asymptotic matching technique to trace the wave amplitude of rays across singularities: Application to lower-hybrid wave propagation in tokamaks
Authors: Hugon Hugo , Bizarro João P. S. , Rodrigues Paulo
Published: August 2020

A most persistent limitation of the geometrical-optics (GO) approximation is the difficulty in integrating the focusing/defocusing term in the equation for the wave amplitude when rays go through singularities (i.e., caustics and cutoffs), points where GO fails and wavelengths and other wave field-related quantities (e.g., the wave amplitude and energy density) become arbitrarily large. A new asymptotic matching (AM) technique is thus presented which allows one to recover the wave amplitude of rays crossing singularities and which improves on a previous approach [A. H. Glasser and A. Bravo-Ortega, Phys. Fluids 30, 797 (1987)]: it goes higher in the order of the asymptotic expansion about the singular point and eventually leads to a less critical violation of the GO ordering when a ray approaches and crosses a caustic or a cutoff. The implementation of this new AM technique is verified and validated against analytical solutions in slab geometry for the lower-hybrid (LH) cutoff and is illustrated with numerical examples of LH wave propagation in a tokamak plasma, using parameters characteristic of a LH current drive experiment. The new and previous approaches are compared regarding several computed ray quantities (e.g., the second derivatives of the eikonal phase, which contribute to the focusing/defocusing term, as well as the wave amplitude and energy density), the inclusion of more terms in the asymptotic expansion about the singularity making it possible to start, say, jumping the latter in a region where GO is less severely challenged. Practical criteria for AM implementation and for testing the validity of GO and of the asymptotic expansion are also provided and discussed.
Magnetic states of atomic vacancies in graphite probed by scanning tunneling microscopy
Authors: Ko Wonhee , Kim Hyo Won , Cho Yeonchoo , Ku JiYeon , Kwon Hyeokshin , Oh Youngtek , Jung Jin-Wook , Jeon Insu , Suh Hwansoo , Kuk Young , Hwang Sung Woo
Published: August 2020

Intrinsic defects in graphitic materials, like vacancies and edges, have been expected to possess magnetic states from the many-body interaction of localized electrons. However, charge screening from graphite bulk carriers significantly reduces the localization effect and hinders the observation of those magnetic states. Here, we use an ultra-low-temperature scanning tunneling microscope with a high magnetic field to observe the magnetic states of atomic vacancies in graphite generated by ion sputtering. Scanning tunneling spectroscopy reveals localized states at the vacancies, which exhibit splitting at a certain magnetic field whose separation increases with the field strength. The transition is well described by the “Anderson model,” which describes the emergence of localized magnetic states inside the metallic reservoir through electron–electron interaction. The interaction strength is estimated to be between 1 meV and 3 meV, which is supported by the density functional theory calculation. The observation provides an important foundation for application of intrinsic defects to carbon-based spintronic devices.
Skyrmion Brownian circuit implemented in continuous ferromagnetic thin film
Authors: Jibiki Yuma , Goto Minori , Tamura Eiiti , Cho Jaehun , Miki Soma , Ishikawa Ryo , Nomura Hikaru , Srivastava Titiksha , Lim Willy , Auffret Stephane , Baraduc Claire , Bea Helene , Suzuki Yoshishige
Published: August 2020

The fabrication of a circuit capable of stabilizing skyrmions is important for the realization of micro- to nano-sized skyrmion devices. Ultralow power Brownian computers have been theoretically proposed and are a promising example of a skyrmion-based device. However, such devices have not been realized as it would require skyrmions to be stabilized and easily movable within a circuit. Skyrmion circuits fabricated by the etching of ferromagnetic films often decrease the dipolar magnetic field stabilizing the skyrmions, thus preventing their formation. In this study, a skyrmion Brownian circuit has been implemented in a continuous ferromagnetic film with patterned SiO2 capping to stabilize the skyrmion formation. The patterned SiO2 capping controls the saturation field of the ferromagnetic layer and forms a wire-shaped skyrmion potential well, which stabilizes skyrmion formation in the circuit. Moreover, using this patterned SiO2 capping, we have implemented a Y-junction hub circuit exhibiting no pinning site at the junction, contrary to conventional etched hubs. Thus, this technique enables the efficient control of skyrmion-based memory and logic devices to move closer toward the realization of Brownian computers.
High sensitivity, levitated microsphere apparatus for short-distance force measurements
Authors: Kawasaki Akio , Fieguth Alexander , Priel Nadav , Blakemore Charles P. , Martin Denzal , Gratta Giorgio
Published: August 2020

A high sensitivity force sensor based on dielectric microspheres in vacuum, optically trapped by a single, upward-propagating laser beam, is described. Off-axis parabolic mirrors are used both to focus the 1064 nm trapping beam and to recollimate it to provide information on the horizontal position of the microsphere. The vertical degree of freedom is readout by forming an interferometer between the light retroreflected by the microsphere and a reference beam, hence eliminating the need for auxiliary beams. The focus of the trapping beam has a 1/E2 radius of 3.2 µm and small non-Gaussian tails, suitable for bringing devices close to the trapped microsphere without disturbing the optical field. Electrodes surrounding the trapping region provide excellent control of the electric field, which can be used to drive the translational degrees of freedom of a charged microsphere and the rotational degrees of freedom of a neutral microsphere, coupling to its electric dipole moment. With this control, the charge state can be determined with single electron precision, the mass of individual microspheres can be measured, and empirical calibrations of the force sensitivity can be made for each microsphere. A force noise of <1 × 10−17 N/Hz, which is comparable to previous reports, is measured on all three degrees of freedom for 4.7 µm diameter, 84 pg silica microspheres. Various devices have been brought within 1.6 µm of the surface of a trapped microsphere. Metrology in the trapping region is provided by two custom-designed microscopes providing views in the horizontal and one of the vertical planes. The apparatus opens the way to performing high sensitivity three-dimensional force measurements at a short distance.
Concurrent magneto-optical imaging and magneto-transport readout of electrical switching of insulating antiferromagnetic thin films
Authors: Schreiber F. , Baldrati L. , Schmitt C. , Ramos R. , Saitoh E. , Lebrun R. , Kläui M.
Published: August 2020

We demonstrate stable and reversible current induced switching of large-area (>100 μm2) antiferromagnetic domains in NiO/Pt by performing concurrent transport and magneto-optical imaging measurements in an adapted Kerr microscope. By correlating the magnetic images of the antiferromagnetic domain changes and magneto-transport signal response in these current-induced switching experiments, we disentangle magnetic and non-magnetic contributions to the transport signal. Our table-top approach establishes a robust procedure to subtract the non-magnetic contributions in the transport signal and extract the spin-Hall magnetoresistance response associated with the switching of the antiferromagnetic domains, enabling one to deduce details of the antiferromagnetic switching from simple transport measurements.
Mixed ion-electron transport in organic electrochemical transistors
Authors: Tu Deyu , Fabiano Simone
Published: August 2020

Organic electrochemical transistors (OECTs) have shown great promise in a variety of applications ranging from digital logic circuits to biosensors and artificial synapses for neuromorphic computing. The working mechanism of OECTs relies on the mixed transport of ionic and electronic charge carriers, extending throughout the bulk of the organic channel. This attribute renders OECTs fundamentally different from conventional field effect transistors and endows them with unique features, including large gate-to-channel capacitance, low operating voltage, and high transconductance. Owing to the complexity of the mixed ion-electron coupling and transport processes, the OECT device physics is sophisticated and yet to be fully unraveled. Here, we give an account of the one- and two-dimensional drift-diffusion models that have been developed to describe the mixed transport of ions and electrons by finite-element methods and identify key device parameters to be tuned for the next developments in the field.
Piezoresponse force microscopy imaging and its correlation with cantilever spring constant and frequency
Authors: Solís Canto O. , Murillo-Bracamontes E. A. , Gervacio-Arciniega J. J. , Toledo-Solano M. , Torres-Miranda G. , Cruz-Valeriano E. , Chu Y. H. , Palomino-Ovando M. A. , Enriquez-Flores C. I. , Mendoza M. E. , Hmŏk H’Linh , Cruz M. P.
Published: August 2020

Single-frequency piezoresponse force microscopy (PFM) images of a BiFeO3/DyScO3(110) thin film, obtained with long (kc = 0.82 N/m) and short (kc = 7.64 N/m) cantilevers, were analyzed as a function of the applied voltage frequency. For long cantilevers, the electrostatic and electrostrictive contributions were identified. These contributions were reduced with a frequency near the second mode of the contact resonance; while for short cantilevers, the first mode was necessary. A method for domain structure analyses, to discriminate a ferroelectric behavior from a non-ferroelectric, through the optimization of PFM images, is also described. The analysis can be extended to cantilevers with different spring constants and ferroelectric materials.
Displacement of carbon atoms in few-layer graphene
Authors: Wang Jing , Chen Di , Chen Tianyi , Shao Lin
Published: August 2020

Molecular dynamics simulations were performed to study the susceptibility of carbon atom displacement under electron irradiation. The mapping of threshold displacement energies at different recoiling directions showed that the energies are very sensitive to the layer configurations and positions of neighboring atoms. Carbon atoms on the top and the bottom layers of few-layer graphene are most vulnerable to irradiation damage due to lack of constraints from the neighboring graphene layers. As indirect experiment evidence, transmission electron microscopy was performed on the edge of folded few-layer graphene, which made it possible to reveal “the inside” and compare irradiation tolerance of atoms at different layers, by using an electron analysis beam for both displacement creation and in situ characterization.
Quantum design for singlet-fission-induced nonlinear optical systems: Effects of π-conjugation length and molecular packing of butterfly-shaped acenes
Authors: Tonami Takayoshi , Nagami Takanori , Okada Kenji , Yoshida Wataru , Miyamoto Hajime , Nakano Masayoshi
Published: August 2020

Theoretical molecular design of efficient nonlinear optical (NLO) systems using singlet fission (SF) is performed for butterfly-shaped acenes with/without nitrogen and sulfur substitutions using quantum chemical calculations, exciton dynamics simulations, and Marcus theory. It is found that these large systems meet the energy level matching conditions of efficient SF and exhibit superior third-order NLO properties (second hyperpolarizability γ at the molecular scale) to a typical SF molecule, pentacene. In addition, we investigate SF rates and γ in the correlated triplet pair [1(TT)] state generated by SF for various slip-stacked dimer models of these systems. For molecular packing with relatively large 1(TT) yields, a significant increase in γ/monomer in the 1(TT) state is observed, which is in good agreement with the electronic-coupling-based design guidelines obtained from our previous study. In particular, the butterfly-shaped acenes involving heteroatoms are found to exhibit a significant increase in γ/monomer as compared to the other systems. By analyzing the excitation properties in the 1(TT) state and intermolecular orbital interactions, we clarify the origin of such γ enhancement. The obtained results contribute to the construction of design guidelines for efficient SF-induced-NLO materials and demonstrate that butterfly-shaped acenes have the potential to surpass conventional NLO systems.
Mie scattering revisited: Study of bichromatic Mie scattering of electromagnetic waves by a distribution of spherical particles
Authors: Olivares Ignacio E. , Carrazana P.
Published: August 2020

Two experiments to measure the size of microscopic dielectric spherical particles immersed in purified water with spheres of a nominal diameter 5.2 ± 0.15 μm have been carried out in order to revisit Mie scattering techniques. The first experiment uses a 1 mW helium–neon (He–Ne) laser with a wavelength of 632.8 nm, while the second one is carried out using a diode laser of 780.0 nm wavelength and a nominal power of 80 mW. The distribution of the scattered light intensity is recorded experimentally, and since the theoretical background has been known for several decades (see references), only a modest amount of theory is included. We considered the Mie scattering by a set of spheres of different diameters in our case with a distribution of sphere diameters with mean diameter 5.2 μm and standard deviation 0.15 μm. Our measured Mie scattering angular distribution accounts for the effect of the diameter distribution, which we assume to be a Gaussian distribution. Our results indicate that there is very good agreement between experiment and theoretical predictions. The technique we offer here is found to be useful to familiarize technicians who work in the areas of applied optics, such as chemistry, electronics, water contamination, and optical instruments with Mie scattering techniques, and who may not have a formal introduction to the electromagnetic theory. One specific area in which these techniques might be useful is the study of aerosols that may arise when naturally produced droplets from humans, such as those produced by coughing, sneezing, talking, and breathing, are present, as it happens in response to the Severe Acute Respiratory Syndrome Coronavirus 2, also known as SARS-CoV-2.
On coherent structures of spatially oscillating planar liquid jet developing in a quiescent atmosphere
Authors: Arote Ashish , Bade Mukund , Banerjee Jyotirmay
Published: August 2020

The momentum transport and entrainment of a developing plane jet are dominated by coherent structures. Percipience about the formation, evolution, and interaction of these coherent structures for oscillating planar jets remains unclear. In the present study, numerical investigations are reported for analyzing spatially oscillating planar jets by solving Navier–Stokes equations coupled with the volume of fluid method to track the air–water interface. Coherent structures in the flow for Reynolds numbers (Re) 4500 and 500 are identified using Q-criterion. It is demonstrated that for oscillating jets, the spread and entrainment increase with an increase in Re. These jet characteristics are greatly influenced by the head vortices, which transform into a pair of hairpin vortices, which further undergo leapfrogging. This jet front dynamics is found to be dampened by viscous forces. The numerical results also suggest the existence of sideways hairpin vortices that expel the fluid by forming a channel and are significantly subdued at low Re. A peculiar merging of span-wise Kelvin–Helmholtz rollers at low Re is also reported in the present study. Furthermore, the dominant flow structures are identified and analyzed using proper orthogonal decomposition and dynamic mode decomposition. The results demonstrate the dominance of coherent structures at the downstream for higher Re with vortices in the near field at the jet peaks also contributing to the flow field dynamics.
Kinetic study on electro-nucleation of water in a heterogeneous propane nano-bubble system to form polycrystalline ice I
c
Authors: Ghaani Mohammad Reza , English Niall J.
Published: August 2020

Elucidating the underlying mechanisms of water solidification in heterogeneous systems is crucially important for a panoply of applications; gaining such an understanding has also proven to be very challenging to the community. Indeed, one such example lies in clarifying the thermodynamics and kinetics of electro-crystallization in heterogeneous systems, such as micro- and nano-bubble systems. Here, we employ non-equilibrium molecular dynamics of water in heterogeneous environments experiencing direct contact with a propane gas phase at various temperatures in externally applied static electric fields, elucidating significant external-field effects in inducing poly-crystalline cubic-ice formation. This is in stark contrast with recent work on homogeneous cubic-ice electro-nucleation to produce largely fault-free single crystals. We explore the kinetics of heterogeneous cubic-ice electro-nucleation under different field intensities and thermal conditions and provide an overview of time-dependent dynamics of evolution of polycrystallinity.
Gate-tunable electroluminescence in Aviram–Ratner-type molecules: Kinetic description
Authors: Petrov Elmar G. , Gorbach Victor V. , Ragulya Andrey V. , Lyubchik Andrey , Lyubchik Svetlana
Published: August 2020

A theoretical study of the mechanisms of electroluminescence (EL) generation in photoactive molecules with donor and acceptor centers linked by saturated σ-bonds (molecules of the Aviram–Ratner-type) is presented. The approach is based on the kinetics of single-electron transitions between many-body molecular states. This study shows that the EL polarity arises due to asymmetric coupling of molecular orbitals of the photochromic part of the molecule to the electrodes. The gate voltage controls the power of the EL through the occupancy of the excited singlet state. The shifting of the orbital energies forms a resonant or a non-resonant path for the transmission of electrons through the molecule. The action of the gate voltage is reflected in specific critical voltages. An analytical dependence of the critical voltages on the energies of molecular states involved in the formation of EL, as well as on the gate voltage, was derived for both positive and negative polarities. Conditions under which the gate voltage lowers the absolute value of the bias voltage that is responsible for the activation of the resonance mechanism of EL formation were also established. This is an important factor in control of EL in molecular junctions.
First principles modeling of exciton-polaritons in polydiacetylene chains
Authors: Alvertis Antonios M. , Pandya Raj , Quarti Claudio , Legrand Laurent , Barisien Thierry , Monserrat Bartomeu , Musser Andrew J. , Rao Akshay , Chin Alex W. , Beljonne David
Published: August 2020

Exciton-polaritons in organic materials are hybrid states that result from the strong interaction of photons and the bound excitons that these materials host. Organic polaritons hold great interest for optoelectronic applications; however, progress toward this end has been impeded by the lack of a first principles approach that quantifies light–matter interactions in these systems, which would allow the formulation of molecular design rules. Here, we present a theoretical framework that combines first principles calculations for excitons with classical electrodynamics in order to quantify light–matter interactions. We exemplify our approach by studying variants of the conjugated polymer polydiacetylene, and we show that a large polymer conjugation length is critical toward strong exciton–photon coupling, hence underlying the importance of pure structures without static disorder. By comparing to our experimental reflectivity measurements, we show that the coupling of excitons to vibrations, manifested by phonon side bands in the absorption, has a strong impact on the magnitude of light–matter coupling over a range of frequencies. Our approach opens the way toward a deeper understanding of polaritons in organic materials, and we highlight that a quantitatively accurate calculation of the exciton–photon interaction would require accounting for all sources of disorder self-consistently.
Carbonyl stretch of CH⋯O hydrogen-bonded methyl acetate in supercritical trifluoromethane
Authors: Inafuku Maximiliano , Marceca Ernesto
Published: August 2020

Infrared spectroscopy in the gas phase was used to study the formation reaction of the CH⋯O hydrogen bonding complex involving the CH group of trifluoromethane, as a hydrogen donor, and the carbonyl group of methyl acetate, as a hydrogen acceptor, under different (T, p) conditions. The hydrogen-bonded carbonyl stretch of the molecular pair was monitored in dilute mixtures of methyl acetate in trifluoromethane at near-critical temperatures, from gas- to liquid-like densities. In the gas region, it was possible to discriminate the carbonyl signal of the hydrogen-bonded complex from that of the free ester and have access to their relative concentration. The equilibrium constant of the hydrogen bonding reaction and the standard enthalpy and entropy changes in the process were determined using the spectroscopic data. CH⋯O bonding was favored by lowering temperature or pressurizing F3CH in the mixture, remaining essentially no free carbonyl groups about the critical density. The carbonyl band of the hydrogen-bonded pair appeared as a single symmetric peak up to liquid-like densities, suggesting that the 1:1 methyl acetate-trifluoromethane complex has the most abundant stoichiometry. Spectral features as frequency shift and bandwidth of the hydrogen-bonded carbonyl were studied as a function of temperature and solvent-density. A bathochromic (red) vibrational shift was registered for the bound carbonyl band against density, with a sudden change in behavior in the near-critical region, while the width of this band remains mostly unresponsive.
Ionization wave propagation in a He plasma jet in a controlled gas environment
Authors: Lietz Amanda M. , Barnat Edward V. , Foster John E. , Kushner Mark J.
Published: August 2020

Characterizing ionization wave propagation in low temperature plasma jets is critical to predicting production of reactive species and plasma–surface interactions for biomedical applications and surface functionalization. In this paper, results from optical emission and laser induced fluorescence measurements of the ionization wave in a He plasma jet operating in a controlled gas environment are discussed and used for comparison with numerical modeling. The ionization wave was observed using ICCD (Intensified Charge Coupled Device) imaging and characterized by time and spatially resolved electron density measurements using laser-collision-induced fluorescence. The plasma jet was initially characterized using pure He (nominally at 200 Torr), while varying pressure and voltage. When operating in pure He, the ionization wave broadly expands exiting the plasma tube. Increasing the operating pressure reduces the speed and isotropic expansion of the ionization wave. The jet operated with a humid He shroud was also studied. The humid He shroud results in the electron density increasing and having an annular profile due to the lower ionization potential of H2O compared to He and localized photoionization in the mixing region. Numerical modeling highlighted the importance of resonance radiation emitted by excited states of He, photoelectron emission from the quartz tube, and the kinetic behavior of the electrons produced by photoionization ahead of the ionization front.
Variational determination of the two-electron reduced density matrix within the doubly occupied configuration interaction scheme: An extension to the study of open-shell systems
Authors: Oña Ofelia B. , Torre Alicia , Lain Luis , Alcoba Diego R. , Ríos Elías , Massaccesi Gustavo E.
Published: August 2020

This work proposes to describe open-shell molecules or radicals using the framework of the doubly occupied configuration interaction (DOCI) treatments, so far limited to closed-shell system studies. The proposal is based on considering molecular systems in singlet states generated by adding extra hydrogen atoms located at infinite distance from the target radical system. The energy of this radical is obtained by subtracting the energies of the dissociated hydrogen atoms from that provided by the two-electron reduced density matrix corresponding to the singlet state system in the DOCI space, which is variationally calculated by imposing a set of N-representability conditions. This method is numerically assessed by describing potential energy curves and reduced density matrices in selected ionic and neutral open-shell systems in the doublet spin symmetry ground state.
Enhanced high permittivity BaTiO3–polymer nanocomposites from the cold sintering process
Authors: Sada Takao , Tsuji Kosuke , Ndayishimiye Arnaud , Fan Zhongming , Fujioka Yoshihiro , Randall Clive A.
Published: August 2020

The dielectric property relations of a series of BaTiO3–polymer composites with a uniquely high-volume fraction of ceramic [(1 − x)BaTiO3–x polytetrafluoroethylene (PTFE), with volume fractions x = 0.025, 0.05, 0.1, and 0.2] are studied. Such high-volume fraction of the BaTiO3 phase is achieved by using the cold sintering process, as it enables a single-step densification of oxides at an extremely low temperature; typically, the volume fractions from other processing methods are limited to ceramic filler volume fractions of ∼0.6. Microstructural and resistivity analyses suggest that the optimal range of the polymer content to effectively enhance the functions is x = 0.05, as higher volume fractions of the polymer hinder the densification of the ceramic. The composite exhibits improved properties such as lower loss tangent, higher resistivity, and high permittivity that vary systematically with x following an empirical mixing law. Here, we consider the composite mixing law trends and the changes to properties, which indicate that size effects are also being induced in the dielectric response, including shift of Tc, broadening of transition, and reduction of permittivity with respect to volume fraction of the PTFE. Our findings provide a new and simple strategy for the fabrication of ceramic–polymer composites with extremely high relative permittivities and resistivities, and these observations all point to a route that can allow us to engineer new types of advanced dielectric materials.
Stress growth shearfree flow from the Oldroyd 8-constant framework
Authors: Saengow C. , Giacomin A. J.
Published: August 2020

Sudden inception of shearfree flows (also called stress growth in extension) is an extremely useful set of rheological measurement techniques for bringing out fluid nonlinearities. The previous predictions of these departures from linearity employed molecular simulation or finite difference solutions. In this work, we deepen our understanding of the physics of these departures by uncovering the exact solutions to a large and diverse framework of constitutive equations: the Oldroyd 8-constant framework. Specifically, we derive the exact analytical solutions for the first and second elongational viscosities in shearfree flow from the Oldroyd 8-constant framework including (I) uniaxial elongational flow, (II) biaxial stretching flow, and (III) planar elongational flow. We close our work with a worked example on analyzing a highly branched system.
Acceptability and feasibility of recruiting women to collect a self-administered vaginal swab at a pharmacy clinic for sexually transmissible infection screening
Authors: Gaydos C. A. , Barnes M. , Holden J. , Silver B. , Smith R. , Hardick J. , Quinn T. C.
Published: August 2020

Willingness to self-collect vaginal swabs at a pharmacy clinic is of interest as a venue to increase sexually transmissible infections (STIs) screening for chlamydia, gonorrhoea and trichomonas. Women self-collected vaginal swabs at the pharmacy, completed questionnaires and received STI results within 2 h. Women with STIs were offered free treatment. A total of 313 of 777 (40.3%) women consented and prevalence for any STI was 3.9%. Questionnaires demonstrated acceptability for self-collection at the pharmacy, with 63% (95% CI 57.3–68) and 32.3% (95% CI 27.4–37.8) indicating they ‘strongly agreed’ or ‘agreed’ that they felt comfortable with pharmacy collection, respectively. Self-collected vaginal swabs for STI testing for women who were at a pharmacy were feasible and acceptable to women.
The extent, significance and amelioration of subsurface acidity in southern New South Wales, Australia
Authors: Condon Jason , Burns Helen , Li Guangdi
Published: August 2020

Soil pH is seldom uniform with depth, rather it is stratified in layers. The soil surface (0–0.02 m) commonly exhibits relatively high pH and overlies a layer of acidic soil of 0.05–0.15 m deep, termed an acidic subsurface layer. Commercial and research sampling methods that rely on depth increments of 0.1 m either fail to detect or under report the presence or magnitude of pH stratification. The occurrence of pH stratification and the presence of acidic subsurface layers may cause the extent of acidity in NSW agricultural land to be underestimated. Though the cause of pH stratification in agricultural systems is well understood, the effect on agricultural production is poorly quantified due in part to inadequate sampling depth intervals resulting in poor identification of acidic subsurface layers. Although liming remains the best method to manage acidic soil, current practices of low pH targets (pHCa 5), inadequate application rates and no or ineffective incorporation have resulted in the continued formation of acidic subsurface layers. Regular monitoring in smaller depth increments (0.05 m), higher pH targets (pHCa > 5.5) and calculation of lime rate requirements that account for application method are required to slow or halt soil degradation by subsurface acidification. If higher pH is not maintained in the topsoil, the acidification of subsurface soils will extend further into the profile and require more expensive operations that mechanically place amendments deep in the soil. Although the use of organic amendments has shown promise to enhance soil acidity amelioration with depth, the longevity of their effect is questionable. Consequently, proactive, preventative management of topsoil pH with lime addition remains the most cost-effective solution for growers.
eHealth Technology in Forensic Mental Healthcare: Recommendations for Achieving Benefits and Overcoming Barriers
Authors: Kip Hanneke , Oberschmidt Kira , Bierbooms Joyce J. P. A.
Published: August 2020

While eHealth technologies such as web-based interventions, mobile apps, and virtual reality have the potential to be of added value for forensic mental healthcare, there is a gap between this potential and the current situation in practice. The goal of this study was to identify recommendations to bridge this gap. In total, 21 semi-structured interviews and 89 questionnaires were conducted in a Dutch forensic mental healthcare sample consisting of professionals, patients, and eHealth experts. Based on the broad range of identified recommendations, it can be concluded that attention should be paid to the characteristics of professionals, patients, technology, and the organization throughout the development, implementation and evaluation of eHealth.
Parasitic photon process versus productive photon process: a theoretical study of free-carrier absorption in conventional and hot-carrier solar cells
Authors: Tsai Chin-Yi
Published: August 2020

The effects of free-carrier absorption on conventional and hot-carriers solar cells are theoretically investigated in this work. The common view that free-carrier absorption in solar cells is ‘parasitic’ is re-examined, with the assistance of a theoretical framework and formulation developed and verified for calculating free-carrier absorption coefficients. In the case of spatial partitioning with photon absorption selectivity (e.g. solar cells with embedded quantum structures), free-carrier-absorption can facilitate and enhance carrier escape processes and increases photocurrents, especially in deep potential wells. Carrier heating resulting from free-carrier absorption is shown to be extremely beneficial to hot-carrier solar cells, especially for heavily-doped wide-band-gap optical absorbers. The energy conversion processes from carrier heating of free-carrier absorption could potentially make ideal hot-carrier solar cells function like solar thermal converters. As a result, their energy conversion efficiency is closer to the thermodynamic limit, regardless of optical absorbers’ band gap energy. It is illustrated that, as an optical process which is not limited by band gap energy, free-carrier absorption could benefit possible materials of hot-carrier solar cells regardless of their band gap energy. From this perspective, free-carrier absorption is far from a ‘parasitic’ process. Its usefulness depends on how we turn it into productive work.
Highly efficient and controllable photoluminescence emission on a suspended MoS2-based plasmonic grating
Authors: Huang Lei , Su Huanhuan , Hu Guohua , Wu Shan , Wang Yongkang , Chen Boyu , Wang Qianjin , Deng Chunyu , Yun Binfeng , Zhang Ruohu , Cui Yiping
Published: August 2020

Being a new class of materials, transition metal dichalcogenides are paving the way for applications in atomically thin optoelectronics. However, the intrinsically weak light–matter interaction and the lack of manipulation ability has lead to poor light emission and tunable behavior. Here, we investigate the fluorescence characteristic of monolayer molybdenum disulfide on a metal narrow-slit grating, where a highly efficient, 471 times photoluminescence enhancement are realized, based on the hybrid surface plasmon polaritons resonances and the decreased influence of substrate. Moreover, the emitted intensity and polarization are controllable due to the polarization-dependent characteristic and anisotropy of grating. The manipulations of light-matter interactions in this special system provide a new insight into the fluorescent emission process and open a new avenue for high-performance low dimensional materials devices designs.
The fabrication of LiNbO3 memristors for electronic synapses using oxygen annealing
Authors: Liang Xiang , Chen Xuhao , Yang Xiaoni , Ni Jing
Published: August 2020

Based on the LiNbO3 (LN) single crystal thin film prepared using Ar+ etching, an LN thin film memristor was fabricated by oxygen annealing. Atomic force microscope, scanning electron microscope and electron paramagnetic resonance test results show that the method uniformly reduces the amount of oxygen vacancies on the surface of the material. The current-voltage scanning (I–V scanning), retention and endurance test results show that this method effectively reduces the possibility of breakdown and increases the retention and endurance performance of the device. By adjusting the parameters of the electric pulse, the annealed sample successfully emulated spike-rate dependent plasticity, pulse-paired facilitation, post-tetanic potentiation, Ebbinghaus forgetting curve and the spike-time dependent plasticity. These results indicate that the device prepared herein could be used as an electronic synapse in the field of brain-like neuromorphic computing systems.
Comparison of the suitability of CBCT- and MR-based synthetic CTs for daily adaptive proton therapy in head and neck patients
Authors: Thummerer Adrian , de Jong Bas A , Zaffino Paolo , Meijers Arturs , Marmitt Gabriel Guterres , Seco Joao , Steenbakkers Roel J H M , Langendijk Johannes A , Both Stefan , Spadea Maria F , Knopf Antje C
Published: August 2020

Cone-beam computed tomography (CBCT)- and magnetic resonance (MR)-images allow a daily observation of patient anatomy but are not directly suited for accurate proton dose calculations. This can be overcome by creating synthetic CTs (sCT) using deep convolutional neural networks. In this study, we compared sCTs based on CBCTs and MRs for head and neck (H&N) cancer patients in terms of image quality and proton dose calculation accuracy.

A dataset of 27 H&N-patients, treated with proton therapy (PT), containing planning CTs (pCTs), repeat CTs, CBCTs and MRs were used to train two neural networks to convert either CBCTs or MRs into sCTs. Image quality was quantified by calculating mean absolute error (MAE), mean error (ME) and Dice similarity coefficient (DSC) for bones. The dose evaluation consisted of a systematic non-clinical analysis and a clinical recalculation of actually used proton treatment plans. Gamma analysis was performed for non-clinical and clinical treatment plans. For clinical treatment plans also dose to targets and organs at risk (OARs) and normal tissue complication probabilities (NTCP) were compared.

CBCT-based sCTs resulted in higher image quality with an average MAE of 40 ± 4 HU and a DSC of 0.95, while for MR-based sCTs a MAE of 65 ± 4 HU and a DSC of 0.89 was observed. Also in clinical proton dose calculations, sCTCBCT achieved higher average gamma pass ratios (2%/2 mm criteria) than sCTMR (96.1% vs. 93.3%). Dose-volume histograms for selected OARs and NTCP-values showed a very small difference between sCTCBCT and sCTMR and a high agreement with the reference pCT.

CBCT- and MR-based sCTs have the potential to enable accurate proton dose calculations valuable for daily adaptive PT. Significant image quality differences were observed but did not affect proton dose calculation accuracy in a similar manner. Especially the recalculation of clinical treatment plans showed high agreement with the pCT for both sCTCBCT and sCTMR.
Kernel-based curve-fitting method with spatial regularization for generation of parametric images in dynamic PET
Authors: Huang Hsuan-Ming
Published: August 2020

Due to high levels of noise in pixel-wise time-activity curves, the indirect method that generates kinetic parametric images from dynamic positron emission tomography (PET) images often results in poor parametric image quality. We have demonstrated that the quality of parametric images can be improved by denoising dynamic PET images, using gradient-free curve-fitting and applying a kernel-based post-filtering to parametric images. However, many gradient-free curve-fitting methods are time-consuming. Moreover, some parameter estimates (e.g. k2 and k3) have large variability. To provide high-quality PET parametric images with low computational cost, we propose a curve-fitting method that incorporates the kernel-based denoising method and the highly constrained backprojection technique into the Levenberg-Marquardt (LM) algorithm. We conducted a simulation study to evaluate the performance of the proposed curve-fitting method. Dynamic PET images were reconstructed using the expectation-maximization (EM) algorithm and were denoised before parameter estimation. Compared to the LM algorithm with and without the kernel-based post-filtering, the proposed method achieved superior performance, offering a decrease in both bias and coefficient of variation (CV) on all parametric images. Overall, the proposed method exhibited lower bias and slightly higher CV than the gradient-free pattern search method with the kernel-based post-filtering (PatS-K). Moreover, the computation time of the proposed method was about 18 times lower than that of the PatS-K method. Finally, we show that the proposed method can further improve the quality of parametric images when dynamic PET images are reconstructed using the kernel-based EM algorithm.