bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling influence of Poisson's contraction on squeeze film levitation of planar objects
Authors: Almurshedi A. , Atherton M. , Mares C. , Stolarski T.
Published: March 2019

Poisson's contraction effect is utilised to generate squeeze film levitation and is investigated through a computer model and validated experimentally. A finite element model (ANSYS) is verified by the experimental testing of five different plate designs. Each plate is subjected to uniaxial plain stress by an arrangement of two hard piezoelectric actuators bounded to the bottom of the plate and driven with DC and AC voltages. It is observed that a pulsating dimple or crest shape along the longitudinal axis in the central area of the plate is created due to Poisson's contraction, generating a squeeze-film between the plate and a levitated object. The separation distance between the floating planar object and the plate is analysed using computational fluid dynamics (ANSYS) and experimentally measured by a laser sensor. A good agreement has been found between model predictions and experimental results.
Perturbation of eddy-currents by one inclusion in liquid metal
Authors: Guichou R. , Ayroles H. , Zamansky R. , Bergez W. , Tordjeman Ph. , Paumel K.
Published: March 2019

In this article, we present an analytical model to calculate the perturbation of the magnetic vector potential due to a non-conducting inclusion in a liquid metal translated at constant velocity. The model is valid for a low magnetic Reynolds number, Rem, and a low shielding parameter, Sω. We establish that the first order perturbation of the vector potential can be directly obtained from the value of the unperturbed eddy-current calculated at the location of the inclusion. An ECFM (Eddy-Current FlowMeter) device has been designed to validate the model and to study the frequency effects of the eddy-current and the volume of one inclusion and its location. We observe a good agreement between the model predictions and experimental data within the limit of the validity of the model. Based on scaling analysis, we show that a unique relation exists between the perturbation of the emf (electromotive force) measured with the ECFM and the volume of the inclusion and its location, which reflects the self-similarity of the model solution.
Exciton states and oscillator strength in few-layer α-tellurene
Authors: Gao Qiang , Li Xueping , Fang Lizhen , Wang Tianxing , Wei Shuyi , Xia Congxin , Jia Yu
Published: March 2019

Tellurene is an elementary two-dimensional (2D) semiconductor material that has attracted intensive attention. Here, first-principles methods are used to explore the effects of excitons on the optical properties of few-layer α-tellurene by considering the thickness and strain effects. Compared to other 2D materials, an α-tellurene monolayer possesses the characteristics of bound exciton states with a binding energy of 0.18 eV and a high optical absorption and oscillator strength in the infrared region. In addition, increasing the thickness and biaxial strain can cause a red-shift of the absorption spectra. The obtained results enrich the current understanding of the underlying physical mechanisms of α-tellurene, which are useful when designing related optoelectronic nanodevices.
Polarization-dependent XEOL: Comparison of peculiar near-band-edge emission of non-polar a-plane GaN and ZnO wafers
Authors: Lin Bi-Hsuan , Wu Yung-Chi , Lee Jyh-Fu , Tang Mau-Tsu , Hsieh Wen-Feng
Published: March 2019

Polarization-dependent hard X-ray excited optical luminescence (XEOL) spectroscopy was used to study the properties of near-band-edge (NBE) emission of non-polar a-GaN and a-ZnO wafers. We found similar behaviors of a-GaN with a-ZnO that include the positive intensity jump and the blue shift of the NBE emission peak in the XEOL spectrum following the polarization-dependent X-ray absorption near-edge structure (XANES) as the X-ray energy is tuned across the Ga or Zn K-edge. Furthermore, as the X-ray energy is set above the K-edges, different oscillations of XEOL, also following the XANES, were observed depending upon the directions of the excitation X-ray electric field. However, the blue shift of a-ZnO is about two times larger than that of a-GaN that results from the larger polar field in a-ZnO than that in a-GaN. For both a-GaN and a-ZnO, the above K-edge excited oscillations in XANES and XEOL spectra, where the polarization is set parallel to the c-axis, are attributed to simultaneous excitations of the π-bond along the c-axis and in-plane σ-bonds, whereas only the in-plane σ-bonds are excited for the polarization perpendicular to the c-axis. Therefore, these polarization dependent oscillation features of XEOL yields that follow the fluorescence yields can be used as an alternative way to determine the crystallographic orientations.
Piezo-phototronic enhanced photoresponsivity based on single CdTe nanowire photodetector
Authors: Wang Xiaowu , Dai Guozhang , Chen Yang , Mo Xindi , Li Xing , Huang Weihong , Sun Jia , Yang Junliang
Published: March 2019

The piezo-phototronic effect utilizes the piezo-polarization charge to modify the energy band diagram at the local interface/junction and manipulate the optoelectronic processes of charge carriers, which have provided a promising approach to improve the performance of photoelectric devices. In this paper, we report on the fabrication of single ultra-fine CdTe nanowire (NW) piezo-phototronic photodetectors (PDs). The structure and morphology of the as-synthesized CdTe NWs is characterized in detail. The result shows that the CdTe NWs have a single crystalline zinc blende structure, with its diameter narrowing to about 20 nm. The flexible Ag-CdTe NW-Ag lateral PDs are prepared on the polyethylene terephthalate substrate, showing a broadband photoresponse from ultraviolet to near infrared (NIR) (325-808 nm). By introducing the piezo-phototronic effect, strain-induced piezoelectric polarization charges effectively enhance the performances of the NIR PDs (808 nm) by 430% in photocurrent and 427% in photoresponsivity. The physical mechanism is carefully investigated by analyzing the energy band diagrams at the local metal–semiconductor interface under mechanical deformations. The ultra-fine structure with a larger piezoelectric coefficient is attributed to the enhancement of photoresponsivity. This investigation demonstrates an efficient prototype of the broad-wavelength piezo-phototronic PD based on the ultra-fine CdTe NWs, which provides an effective route to enhance the performance of optoelectronic devices.
Slope efficiency of integrated external cavity hybrid lasers: A general model and analysis
Authors: Zeng Siwei , Zhao Xiaolei , Zhu Yeyu , Dove Charles , Zhu Lin
Published: March 2019

The integrated tunable external cavity diode laser (ECDL) plays an important role in many emerging applications, such as LiDAR, integrated free-space optical communication, integrated nonlinear optics, quantum information processing, and data center optical interconnects. Based on the III-V/silicon or III-V/silicon nitride hybrid integration, chipscale tunable ECDL could achieve a broad wavelength tuning range (>100nm) and very narrow linewidth (<10kHz) with the help of micro-ring resonators. However, most hybridly integrated ECDLs exhibit a low slope efficiency (<0.1W/A), which severely limits the laser performance. We have developed a general numerical model for the hybrid laser and investigated several methods to improve its slope efficiency. We show that the slope efficiency of the hybrid laser can be efficiently increased by controlling the external cavity phase, improving the coupling between the laser chip and passive chip, using optimized anti-reflection and high reflection coatings, and reducing the laser intrinsic loss. We have also experimentally built an arrayed waveguide grating (AWG) based hybrid laser and shown that the numerical simulation results match well with the experimental results.
Variety of rotation modes in a small chain of coupled pendulums
Authors: Bolotov Maxim I. , Munyaev Vyacheslav O. , Kryukov Alexey K. , Smirnov Lev A. , Osipov Grigory V.
Published: March 2019

This article studies the rotational dynamics of three identical coupled pendulums. There exist two parameter areas where the in-phase rotational motion is unstable and out-of-phase rotations are realized. Asymptotic theory is developed that allows us to analytically identify borders of instability areas of in-phase rotation motion. It is shown that out-of-phase rotations are the result of the parametric instability of in-phase motion. Complex out-of-phase rotations are numerically found and their stability and bifurcations are defined. It is demonstrated that the emergence of chaotic dynamics happens due to the period doubling bifurcation cascade. The detailed scenario of symmetry breaking is presented. The development of chaotic dynamics leads to the origin of two chaotic attractors of different types. The first one is characterized by the different phases of all pendulums. In the second case, the phases of the two pendulums are equal, and the phase of the third one is different. This regime can be interpreted as a drum-head mode in star-networks. It may also indicate the occurrence of chimera states in chains with a greater number of nearest-neighbour interacting elements and in analogical systems with global coupling.
Modeling vibrational anharmonicity in infrared spectra of high frequency vibrations of polyatomic molecules
Authors: Sibert Edwin L.
Published: March 2019

In this perspective, we review the challenges of calculating spectra of high-frequency XH vibrations (where X = C, N, or O) of molecules and small clusters. These modes are often coupled to nearly degenerate overtone and combination bands, greatly complicating the interpretation of the spectra. When molecules or clusters contain multiple XH groups, assigning spectra is difficult, especially when multiple conformers are present. We consider approaches appropriate for addressing these difficulties, focusing on systems with more than 15 atoms. At this size, the densities of states of these fundamentals are sufficiently high that it is not possible to calculate eigenstate-resolved spectra. Nonetheless, combining perturbation theory, empirical scalings of vibrational frequencies, and variational treatments of reduced dimensional Hamiltonians, one can identify and model the vibrational coupling pathways that influence observed spectral features. We describe how these methods have evolved through time as electronic structure methods and computational resources have advanced.
Wafer-scale on-chip synthesis and field emission properties of vertically aligned boron nitride based nanofiber arrays
Authors: Long Hu , Pham Thang , Yan Aiming , Guo Zhen , Ishida Hiroya , Shi Wu , Turner Sally , Gilbert S. Matt , Zettl Alex
Published: March 2019

One dimensional boron nitride (BN) nanomaterials with a high aspect ratio are of great interest due to their unique properties and potential applications. However, BN nanomaterials are generally difficult to synthesize. Here, we describe the creation of arrays of vertically aligned pure BN nanofibers and BN coated carbon nanofibers, fabricated on-chip via a straightforward template-assisted chemical conversion reaction. The template, a glassy carbon nanofiber array, is produced by plasma processing of conventional photoresists. The method is highly controllable, patternable, and scalable, and the final arrays can be fabricated over large areas with a controlled fiber length. We characterize the electron field emission properties of the BN-coated carbon nanofiber array and find a large field enhancement factor, low turn-on voltage, and good stability. The outstanding field emission performance results from the small tip size and high aspect ratio of the nanofiber as well as the high chemical stability and high thermal conductivity of the BN coating.
Non-contact
in situ
microwave material measurements for high temperature process monitoring
Authors: T. Sivaprakasam Balamurugan , Krishnamurthy C. V. , Arunachalam Kavitha
Published: March 2019

Non-contact real time microwave measurement and signal analysis techniques to extract high temperature material parameters from the mono-static reflections gathered by a compact air cooled corrugated horn are presented in this work. Non-contact in situ microwave measurements gathered over 20–24 GHz inside a closed furnace were processed to identify the thermodynamic phase change temperature of metal and glass melts. The melting point of aluminum alloy and glass transition of a borosilicate glass matrix extracted from the time gated and processed microwave measurements were in good agreement with differential scanning calorimetry measurements. Thus, the ability to measure high temperature material process parameters using non-contact microwave measurements is demonstrated.
Adiabatic quantum-flux-parametron with π Josephson junctions
Authors: Arai Kota , Takeuchi Naoki , Yamashita Taro , Yoshikawa Nobuyuki
Published: March 2019

Superconductor/ferromagnet/superconductor Josephson junctions across which the phases of superconducting order parameters are shifted by π in the ground state are called π Josephson junctions (π-JJs). Recently, several groups have established the fabrication technology of π-JJs so that superconductor logic families exploit π-JJs to improve circuit performance. In this paper, we investigate the advantages of π-JJs in adiabatic quantum-flux-parametron (AQFP) logic, which is an adiabatic superconductor logic based on the quantum-flux-parametron. First, we show that AQFP logic with π-JJs (π-AQFP) can operate using only π-JJs and can be powered and clocked in the same way as the conventional AQFP logic. Then, we show that π-AQFP logic can realize inverters without using signal transformers, which generally occupy a large area in AQFP gates and are difficult to miniaturize. We demonstrate π-AQFP inverters using numerical simulation to establish that π-AQFP logic operates adiabatically and robustly. Our results show that π-JJs can be easily incorporated into AQFP logic and enhance the circuit density of AQFP logic.
Effect of Sr doping on structure, morphology, and transport properties of Bi2Se3 epitaxial thin films
Authors: Volosheniuk S. O. , Selivanov Yu. G. , Bryzgalov M. A. , Martovitskii V. P. , Kuntsevich A. Yu.
Published: March 2019

We report molecular beam epitaxy growth of Sr-doped Bi2Se3 films on the (111) BaF2 substrate, aimed to realize unusual superconducting properties inherent to SrxBi2Se3 single crystals. Despite the wide range of the compositions, we do not achieve superconductivity. To explore the reason for this, we study the structural, morphological, and electronic properties of the films and compare them with the corresponding properties of the single crystals. The dependence of the c-lattice constant in the films on the Sr content appears to be more than an order of magnitude stronger than that in the crystals. Correspondingly, all other properties also differ substantially, indicating that Sr atoms get different positions in lattices. We argue that these structural discrepancies arise from essential differences in growth conditions. Our research calls for more detailed structural studies and novel growth approaches for the design of superconducting SrxBi2Se3 thin films.
The interplay of channel geometry and molecular features determines diffusion in lipidic cubic phases
Authors: Ghanbari Reza , Assenza Salvatore , Mezzenga Raffaele
Published: March 2019

The transport behavior of inverse bicontinuous cubic phases is experimentally investigated as the combined outcome of solute molecular structure and geometrical details of the confining symmetry. Molecular diffusion is discussed in relation to curvature, bottlenecks, and interfacial properties of each cubic phase. Point-like molecules show faster diffusion across the double diamond (Pn3¯m) symmetry, while unfolded macromolecules display better performance inside the double primitive (Im3¯m) cubic phase. The former observation is in agreement with previous simulation work, whereas the latter indicates that dedicated theory needs to be developed for diffusing polymers. Furthermore, the effect of electrostatic interactions is assessed by a study of diffusion of nanoparticles and is rationalized via a combination of simulations and theoretical considerations as the result of a competition between water mobility and geometrical features of the channel.
Deep traps and persistent photocapacitance in β-(Al0.14 Ga0.86)2O3/Ga2O3 heterojunctions
Authors: Polyakov A. Y. , Smirnov N. B. , Schemerov I. V. , Chernykh A. V. , Yakimov E. B. , Kochkova A. I. , Yang Jiancheng , Fares Chaker , Ren F. , Pearton S. J.
Published: March 2019

Persistent photocapacitance (PPC) was observed in β-(Al0.14Ga0.84)2O3/n+Ga2O3 heterojunctions at low temperatures. The effect is seen in capacitance-frequency measurements under illumination and in admittance spectra after illumination. In the latter case, the capacitance versus frequency curve after illumination returned to its dark values only at temperatures between 225 and 275 K. Prominent hole-trap-like peaks in optical deep level transient spectroscopy (ODLTS) near 130 K were attributed to quenching with temperature of the PPC effect. The phenomena were assigned to electrons being excited from deep traps in the (Al0.14Ga0.86)2O3 barrier into the two-dimensional electron gas (2DEG) in the Ga2O3 substrate. The reverse process then involves excitation of non-equilibrium electrons in the 2DEG back into the ternary barrier layer and subsequent re-capture by the host deep traps. The effective barrier height for this recovery process was ∼0.2 eV, as estimated from ODLTS measurements. The spectral dependence of the effect suggests the presence of deep traps with optical ionization thresholds near 1 eV and ∼2.3 eV. The shift of the threshold voltage necessary to deplete the 2DEG as a function of the photon energy during illumination at room temperature indicates that the most prominent centers in the barrier have an optical ionization energy near 2.3 eV and a sheet density of ∼1012 cm−2. In microcathodoluminescence (MCL) spectra of the heterojunction, a blue shift by 0.2 eV of the MCL band near 3.1 eV dominant in the substrate and the emergence of a weak MCL peak near 4.8 eV were observed. Electron beam induced current measurements point to the presence of small local areas where the 2DEG formation is handicapped due to Al composition variations or to defects.
The effect of retro-inverse D-amino acid Aβ-peptides on Aβ-fibril formation
Authors: Xi Wenhui , Hansmann Ulrich H. E.
Published: March 2019

Peptides build from D-amino acids resist enzymatic degradation. The resulting extended time of biological activity makes them prime candidates for the development of pharmaceuticals. Of special interest are D-retro-inverso (DRI) peptides where a reversed sequence of D-amino acids leads to molecules with almost the same structure, stability, and bioactivity as the parent L-peptides but increased resistance to proteolytic degradation. Here, we study the effect of DRI-Aβ40 and DRI-Aβ42 peptides on fibril formation. Using molecular dynamics simulations, we compare the stability of typical amyloid fibril models with such where the L-peptides are replaced by DRI-Aβ40 and DRI-Aβ42 peptides. We then explore the likelihood for cross fibrilization of Aβ L- and DRI-peptides by investigating how the presence of DRI peptides alters the elongation and stability of L-Aβ-fibrils. Our data suggest that full-length DRI-peptides may enhance the fibril formation and decrease the ratio of soluble toxic Aβ oligomers, pointing out potential for D-amino-acid-based drug design targeting Alzheimer’s disease.
InAs/InP quantum dots stacking: Impact of spacer layer on optical properties
Authors: Xiong Yiling , Zhang Xiupu
Published: March 2019

The optical properties of a vertical multilayer stack of semiconductor self-assembled quantum dots (QDs) depend on the coupling status. We present an improved modeling method for analysis of QD stacks, consisting of several separate steps in the elastic strain analysis, to reproduce the realistic unidirectional strain accumulation along the QD growth direction from lower and upper dots. Based on this modeling method, by varying the spacer thickness, we systematically study a large variety of QD stack structures, for better understanding the influence of strain and electronic coupling mechanisms. A “quasi continuum band” or highly degenerate excited state (ES) is found in the closely multi-stacked QDs, probably accounting for the occurrence of distinct blueshifting of the photoluminescence peak wavelength for the decreasing spacer thickness. The enhanced ES emission from this type of stacking QD modeled by using rate equations may pave a way for designing potential high-performance laser devices operating on ES.
Atomistic simulations of molten carbonates: Thermodynamic and transport properties of the Li2CO3—Na2CO3—K2CO3 system
Authors: Desmaele Elsa , Sator Nicolas , Vuilleumier Rodolphe , Guillot Bertrand
Published: March 2019

Although molten carbonates only represent, at most, a very minor phase in the Earth’s mantle, they are thought to be implied in anomalous high-conductivity zones in its upper part (70–350 km). Besides, the high electrical conductivity of these molten salts is also exploitable in fuel cells. Here, we report quantitative calculations of their properties, over a large range of thermodynamic conditions and chemical compositions, which are a requisite to develop technological devices and to provide a better understanding of a number of geochemical processes. To model molten carbonates by atomistic simulations, we have developed an optimized classical force field based on experimental data of the literature and on the liquid structure issued from ab initio molecular dynamics simulations performed by ourselves. In implementing this force field into a molecular dynamics simulation code, we have evaluated the thermodynamics (equation of state and surface tension), the microscopic liquid structure and the transport properties (diffusion coefficients, electrical conductivity, and viscosity) of molten alkali carbonates (Li2CO3, Na2CO3, K2CO3, and some of their binary and ternary mixtures) from the melting point up to the thermodynamic conditions prevailing in the Earth’s upper mantle (∼1100–2100 K, 0–15 GPa). Our results are in very good agreement with the data available in the literature. To our knowledge, a reliable molecular model for molten alkali carbonates covering such a large domain of thermodynamic conditions, chemical compositions, and physicochemical properties has never been published yet.
Van der Waals heterostructures of P, BSe, and SiC monolayers
Authors: Idrees M. , Din H. U. , Khan S. A. , Ahmad Iftikhar , Gan Li-Yong , Nguyen Chuong V. , Amin B.
Published: March 2019

Electronic structure, optical, and photocatalytic properties of P, BSe, and SiC monolayers and their van der Waals heterostructures are investigated by (hybrid) first-principle calculations. The stability of the heterostructures and their corresponding induced-strain/unstrain monolayers are confirmed by the phonon spectra calculations. Similar to the corresponding parent monolayers, P-BSe (BSe-SiC) heterostructures are indirect type-II (type-I) bandgap semiconductors. A tensile strain of 10% (2%) transforms P-BSe (BSe-SiC) to type-I (type-II) direct bandgap nature. Interestingly, irrespective of the corresponding monolayers, the P-SiC heterostructure is a direct bandgap (type-II) semiconductor. The calculated electron and hole carrier mobilities of these heterostructures are in the range of 1.2×104cm2/Vs to 68.56×104cm2/Vs. Furthermore, absorption spectra are calculated to understand the optical behavior of these systems, where the lowest energy transitions are dominated by excitons. The valence and conduction band edges straddle the standard redox potentials in P-BSe, BSe-SiC, and P-SiC (strained) heterostructures, making them promising candidates for water splitting in the acidic solution. An induced compressive strain of 3.5% makes P suitable for water splitting at pH=0.
A combined study of thermodynamic and first-principle calculation for single bond energy of Cu clusters
Authors: Li H. , Du H. N. , He X. W. , Shen Y. Y. , Zhang H. X. , Xu C. X.
Published: March 2019

In the past, single bond energy of nanomaterials did not attract much attention, since many of their properties show a direct relation to cohesive energy. However, it is the single bond energy that determines the interaction between two atoms and even their bond lengths. Through introducing the bond number and the size-dependent cohesive energy model, the size-related single bond energy ɛ(N) of Cu clusters is resolved in this work, with the support of a thermodynamic method combined with first-principle calculation. It is found that the single bond is gradually strengthened as the size drops when compared with the bulk. Moreover, this enhanced bond strength is greatly important, especially in analyzing the Raman shift of semiconductor nanoparticles.
Photoresponsivity enhancement in monolayer MoS2 by rapid O2:Ar plasma treatment
Authors: Jadwiszczak Jakub , Li Gen , Cullen Conor P. , Wang Jing Jing , Maguire Pierce , Duesberg Georg S. , Lunney James G. , Zhang Hongzhou
Published: March 2019

We report up to ten-fold enhancement of the photoresponsivity of monolayer molybdenum disulfide (MoS2) by treatment with O2:Ar (1:3) plasma. We characterize the surface of plasma-exposed MoS2 by TEM, Raman, and PL mapping and discuss the role of MoOx in improving the photocurrent generation in our devices. At the highest tested laser power of 0.1 mW, we find ten-fold enhancements to both the output current and carrier field-effect mobility at the illumination wavelength of 488 nm. We suggest that the improvement of electrical performance is due to the surface presence of MoOx resulting from the chemical conversion of MoS2 by the oxygen-containing plasma. Our results highlight the beneficial role of plasma treatment as a fast and convenient way of improving the properties of synthetic 2D MoS2 devices for future consideration in optoelectronics research.
Generalized oscillator strengths of the low-lying valence-shell excitations of N2, O2, and C2H2 studied by fast electron and inelastic x-ray scattering
Authors: Liu Ya-Wei , Peng Yi-Geng , Xiong Tao , Wang Shu-Xing , Huang Xin-Chao , Wu Yong , Zhu Lin-Fan
Published: March 2019

The generalized oscillator strengths of the low-lying valence-shell excitations of N2, O2, and C2H2 have been studied by the high-energy electron scattering, the high-resolution inelastic X-ray scattering, and the multireference single- and double-excitation configuration-interaction methods. Good agreement between the present electron-scattering results and the X-ray-scattering ones for the a′′1Σg+v′=0 and a′′1Σg+v′=1+b1Πuv′=0 excitations of N2 and the A′3Δu excitation of O2 is achieved in the small squared momentum transfer region, while obvious discrepancies among them are observed in the large squared momentum transfer region. This phenomenon indicates that the first Born approximation is satisfied in the small squared momentum transfer region, while it does not hold in the large squared momentum transfer region at an incident electron energy of 1500 eV, in view of the fact that the first Born approximation is satisfied in the X-ray scattering. In addition, the present calculation for the a′′1Σg+ excitation shows that the traditional assigned v′ = 0 and 1 of the a″1Σg+ excitation correspond to v′ = 9 and 13 of the 21Σg+ excitation and reproduces the X-ray-scattering results of the a′′1Σg+v′=0 excitation very well except the ones in the small squared momentum transfer region. We also report the generalized oscillator strengths of the Ã + B̃ excitations of C2H2, and its profile shows that the bending geometry has great influence on the transition feature.
Kelvin-Helmholtz instability is the result of parity-time symmetry breaking
Authors: Qin Hong , Zhang Ruili , Glasser Alexander S. , Xiao Jianyuan
Published: March 2019

Parity-Time (PT)-symmetry is being actively investigated as a fundamental property of observables in quantum physics. We show that the governing equations of the classical two-fluid interaction and the incompressible fluid system are PT-symmetric, and the well-known Kelvin-Helmholtz instability is the result of spontaneous PT-symmetry breaking. It is expected that all classical conservative systems governed by Newton's law admit PT-symmetry, and the spontaneous breaking thereof is a generic mechanism for classical instabilities. Discovering the PT-symmetry of systems in fluid dynamics and plasma physics and identifying the PT-symmetry breaking responsible for instabilities enable new techniques to classical physics and enrich the physics of PT-symmetry.
Failure to access prescribed pharmaceuticals by older patients with chronic conditions
Authors: McRae Ian , van Gool Kees , Hall Jane , Yen Laurann , Wright Michael
Published: March 2019

Objective
Medication adherence is a significant public health concern. Australian studies of statins show patients facing the highest copayments are the least likely to be adherent. This study examined whether the association identified between adherence and costs for statins also applies to a wider group of medications prescribed for Australian patients with chronic conditions.

Methods
Data from 267086 participants in the Sax Institute’s 45 and Up Study linked to data from the Pharmaceutical Benefits Scheme (PBS) provided by the Department of Human Services were used. Patients using angiotensin II receptor blockers, angiotensin-converting enzyme inhibitors, glitazones and bisphosphonates were identified and classified according to concessional status and whether they had access to the PBS ‘safety net’. Data were analysed using mainly descriptive methods to investigate the association of adherence with cost and other selected covariates.

Results
Across medications, the group facing the highest copayment was least adherent. Speaking a language other than English at home and facing high levels of psychological distress were also associated with lower levels of adherence.

Conclusions
As for statins, the main financial determinant of adherence is cost in the form of prescribed copayments, suggesting that this may apply across many medications.

What is known about the topic?
Previous studies have shown patients’ concern about the costs of pharmaceuticals, and more detailed studies of statins show that the lowest adherence relates to patients facing the highest copayments.

What does this paper add?
This paper provides support for the contention that the results found for statins broadly apply across more medications used by people with chronic conditions.

What are the implications for practitioners?
Although practitioners cannot affect legislated copayments, they can consider the costs of options for medications for patients with chronic conditions, especially those general patients who have not reached the safety net, and they can be aware that patients from homes where English is not spoken and patients with high levels of psychological distress are also likely to have low adherence without intervention.
Use of Non–Face-to-Face Modalities for Emergency Department Screening, Brief Intervention, and Referral to Treatment (ED-SBIRT) for High-Risk Alcohol Use: A Scoping Review
Authors: Biroscak Brian J. , Pantalon Michael V. , Dziura James D. , Hersey Denise P. , Vaca Federico E.
Published: March 2019

Background: The purpose of this review was to examine and chart the “scope” of strategies reported in ED-SBIRT (emergency department-based screening, brief intervention and referral to treatment) studies that employ non–face-to-face (nFtF) modalities for high-risk alcohol use (i.e., risk for alcohol-related injury, medical condition, use disorder) and to identify research gaps in the scientific literature. Methods: The scoping review population included study participants with high-risk alcohol use patterns as well as study participants targeted for primary public health prevention (e.g., adolescent ED patients). Core concepts included SBIRT components among intervention studies that incorporated some form of nFtF modality (e.g., computer-assisted brief intervention). The context encompassed ED-based studies or trauma center studies, regardless of geographic location. After screening a total of 1526 unique references, reviewers independently assessed 58 full-text articles for eligibility. Results: A total of 30 full-text articles were included. Articles covered a period of 14 years (2003–2016) and 19 journal titles. Authors reported the use of a wide range of nFtF modalities across all 3 ED-SBIRT components: “screening” (e.g., computer tablet screening), “brief intervention” (e.g., text message–based brief interventions), and “referral to treatment” (e.g., computer-generated feedback with information about alcohol treatment services). The most frequently used nFtF modality was computerized screening and/or baseline assessment. The main results were mixed with respect to showing evidence of ED-SBIRT intervention effects. Conclusions: There is an opportunity for substance use disorder researchers to explore the specific needs of several populations (e.g., ED patients with co-occurring problems such as substance use disorder and violence victimization) and on several methodological issues (e.g., ED-SBIRT theory of change). Substance use disorder researchers should take the lead on establishing guidelines for the reporting of ED-SBIRT studies—including categorization schemes for various nFtF modalities. This would facilitate both secondary research (e.g., meta-analyses) and primary research design.
The State of Substance Use Education in Master of Social Work Programs: A Content Analysis of Course Listings and Faculty Profiles
Authors: Minnick Dane
Published: March 2019

Background: Substance use is currently a pervasive problem among a large proportion of populations served by the social work profession. Several studies have indicated that social workers routinely provide services to clients with direct and indirect substance use needs, making knowledge of substance use interventions and public policies a necessity for social workers to operate effectively in the field. However, despite the regularity of interaction with substance using clients, previous research has suggested that a significant deficit of substance use education currently exists in Master of Social Work (MSW) programs. Methods: To determine the extent of substance use education currently offered by master's-level schools of social work, a content analysis of course listings and full-time faculty profiles was performed on all Council on Social Work Education–accredited programs in the United States ( N = 263). The goals of the content analysis were (1) to identify the current prevalence and content of substance use education offered to entire cohorts of MSW students at the national and programmatic levels and (2) to examine the capacity of the full-time MSW faculty workforce to deliver substance use education to MSW students in individual programs. Results: The results of the analyses showed that a significant deficit of formal substance use education does exist in the field of social work education, and that a large proportion of programs lack the faculty personnel necessary to sufficiently offer substance use education to their students. Conclusions: The social work profession needs to make a concerted effort to improve substance use education if social work is to ethically and effectively remain at the forefront of mental health practice in the United States.
Training Experiences regarding Pain Management, Addiction, and Drug Diversion of Dentists Enrolled in the National Dental Practice-Based Research Network
Authors: McCauley Jenna L. , Reyes Stephanie , Meyerowitz Cyril , Gordan Valeria V. , Rindal D. Brad , Gilbert Gregg H. , Leite Renata S. , Fillingim Roger B. , Brady Kathleen T. ,   National Dental Practice-Based Research Network Collaborative Group*
Published: March 2019

Background

The purpose of this study was to describe dentists’ training experiences relevant to pain management, addiction, and prescription opioid drug diversion and examine associations between these training experiences and dentists’ opioid prescribing practices.

Methods

A Web-based, cross-sectional survey was conducted among practicing dentist members of the National Dental Practice-Based Research Network (PBRN; N = 822). The survey assessed pain management prescribing practices and training experiences related to pain management and assessment for addiction and drug diversion. Survey data were linked with National Dental PBRN Enrollment Questionnaire data regarding practitioner demographics and practice characteristics.

Results

The majority of dentists (67%) reported prior training in pain management; however, a minority of dentists reported prior training regarding identification and assessment of drug abuse or addiction (48%) or identification of prescription drug diversion (25%). The majority of training experiences across all topics occurred through continuing dental education participation. Dental school training relevant to pain management, addiction, and identification of drug diversion was more prevalent among more recent dental school graduates. Training experiences were associated with prescribing practices.

Conclusions

Results suggest that across multiple levels of training, many dentists are not receiving training specific to addiction assessment and identification of drug diversion. Such training is associated with greater consistency of risk mitigation implementation in practice.
Hydrogels as a water bolus during hyperthermia treatment
Authors: Trefná Hana Dobšíček , Ström Anna
Published: March 2019

The feasibility of using hydrogels as a water bolus during hyperthermia treatment was assessed. Three types of gels, high methoxyl (HM) pectin/alginate, xanthan/locust bean gum (LBG) and xanthan/LBG/agarose were evaluated based on their dielectric, rheological and mechanical properties. The most suitable, xanthan/LBG/agarose gel was further used as a water bolus in a hyperthermia array applicator. The gels composed of polysaccharides carrying low charge displayed dielectric properties close to those of water, while the dielectric properties of HM pectin/alginate gel was deemed unsuitable for the current application. The mechanical examination shows that the xanthan/LBG gel has a non-brittle behaviour at room temperature, in contrast to the agarose gel. The moduli of the xanthan/LBG gel weaken however considerably between the temperature range of 40 °C and 50 °C, reducing its potential to be used as water bolus. The ternary system of xanthan/LBG/agarose had advantageous behaviour as it was dominated by the thermal hysteresis typical of agarose upon temperature increase, but governed by the typical non-brittle behaviour of the xanthan/LBG at low temperatures. The final evaluation within the hyperthermia applicator showed excellent signal transmission from the antennas. The agarose/xanthan/LBG gel reduced the scattering of electromagnetic waves, enabled a tight closure between the body and the antennas, and offered a less bulky solution than the currently used water-filled plastic bags. The results presented here open up a new application area for hydrogels in improving heat delivery during hyperthermia treatment and other near-field microwave applications.
Unexpectedly High Prevalence of Cytomegalovirus DNAemia in Older Children and Adolescents With Perinatally Acquired Human Immunodeficiency Virus Infection
Authors: Yindom Louis-Marie , Simms Victoria , Majonga Edith D , McHugh Grace , Dauya Ethel , Bandason Tsitsi , Vincon Helene , Rylance Jamie , Munyati Shungu , Ferrand Rashida A , Rowland-Jones Sarah L
Published: March 2019

Background

Older children and adolescents with perinatally acquired human immunodeficiency virus (PHIV) infection in Africa experience multiple comorbidities that are not typical of HIV-associated opportunistic infections, including growth impairment and chronic lung disease. We examined associations between plasma cytomegalovirus (CMV) DNA and lung function and growth.

Methods

Plasma CMV DNA loads were measured children aged 6–16 years with PHIV (n = 402) and HIV-uninfected controls (n = 224). The HIV-infected children were either newly diagnosed or known HIV infected and stable on antiretroviral therapy (ART) for >6 months. CMV DNA loads were measured using quantitative polymerase chain reaction. CMV DNAemia was modeled as a time-varying outcome using longitudinal mixed-effects logistic regression.

Results

At enrollment, CMV DNAemia ≥1000 copies/mL (defined as “clinically significant”) was detected in 5.8% of uninfected children, 14.7% of HIV-infected participants stable on ART, and 22.6% of HIV-infected ART-naive children (χ2 = 23.8, P < .001). The prevalence of CMV DNAemia ≥1000 copies/mL was associated with CD4 counts <350 cells/µL. Among HIV-infected ART-naive children, the presence of CMV DNAemia of ≥1000 copies/mL was independently associated with reduced lung function (adjusted odds ratio [aOR] = 3.23; 95% confidence interval [CI], 1.23–8.46; P = .017). Among ART-treated children, stunting was associated with CMV DNAemia of ≥1000 copies/mL (aOR = 2.79; 95% CI, 0.97–8.02; P = .057).

Conclusions

Clinically significant levels of CMV DNAemia were common in older children with PHIV, even those on ART, suggesting a role for inadequately controlled CMV infection in the pathogenesis of PHIV comorbidities in Africa.
A Multicenter, Longitudinal Cohort Study of Cryptococcosis in Human Immunodeficiency Virus–negative People in the United States
Authors: Marr Kieren A , Sun Yifei , Spec Andrej , Lu Na , Panackal Anil , Bennett John , Pappas Peter , Ostrander Darin , Datta Kausik , Zhang Sean X , Williamson Peter R ,   Cryptococcus Infection Network Cohort Study Working Group, Lyons Jennifer , Bhimraj Adarsh , Trotman Robin , Health Cox , Perfect John , Lyon G Marshall , Vazquez Jose , Piwoz Julia , Marr Kieren , Hopkins Johns , Spindel Steven , Wray Dannah , Bennett John , Garcia-Diaz Julia , Nolt Dawn , Subramanian Aruna , Pappas Peter , Schaenman Joanna , Taplitz Randy , Diego San , Miceli Marisa , Lee Samuel A , Nguyen Hong , Pannaraj Pia , Hasbun Rodrigo , Limaye Ajit , Powderly William , Spec Andrej
Published: March 2019

Background

Cryptococcosis is increasingly recognized in people without human immunodeficiency virus (HIV).

Methods

A multicenter, prospective cohort study was performed in 25 US centers. Consenting patients were prospectively followed for ≤2 years. Neurological morbidities were assessed with longitudinal event depiction and functional scores (Montreal Cognitive Assessment [MoCA]). Risks of death were analyzed using Cox regression.

Results

One hundred forty-five subjects were enrolled. Most were male (95; 65.5%) and had immunosuppression (120; 82.8%), including solid organ transplant (SOT; 33.8%), autoimmunity (15.9%), and hematologic malignancies (11.7%). Disease involved the central nervous system (CNS) in 71 subjects (49%). Fever was uncommon, documented in 40 (27.8%) subjects, and absence was associated with diagnostic delay (mean: 48.2 vs 16.5 days; P = .007). Abnormal MoCA scores (<26) were predictive of CNS disease; low scores (<22) were associated with poor long-term cognition. Longitudinal event depiction demonstrated frequent complications in people with CNS disease; 25 subjects (35.2%) required >1 lumbar puncture and 8 (11.3%) required ventriculostomies. In multivariable models, older age (>60 years) was associated with higher risks of death (hazard ratio [HR], 2.14; 95% confidence interval [CI], 1.05–4.38; P = .036), and lower risks were noted with underlying hematologic malignancy (HR, 0.29; 95% CI, 0.09–0.98; P = .05) and prior SOT (HR, 0.153; 95% CI, 0.05–0.44; P = .001).

Conclusions

Despite aggressive antifungal therapies, outcomes of CNS cryptococcosis in people without HIV are characterized by substantial long-term neurological sequelae. Studies are needed to understand mechanism(s) of cognitive decline and to enable better treatment algorithms.
Treatment Outcomes of Patients Switching From an Injectable Drug to Bedaquiline During Short Standardized Treatment for Multidrug-resistant Tuberculosis in Mozambique
Authors: Bastard Mathieu , Molfino Lucas , Mutaquiha Cláudia , Galindo Miriam Arago , Zindoga Pereira , Vaz Deise , Mahinça Ivan , DuCros Philipp , Rusch Barbara , Telnov Alex
Published: March 2019

Bedaquiline was recommended by the World Health Organization as the preferred option in treatment of multidrug-resistant tuberculosis (MDR-TB) with long regimens. However, no recommendation was given for the short MDR-TB regimen. Data from our small cohort of patients who switched from injectable drug to bedaquiline suggest that a bedaquiline-based short regimen is effective and safe.
Genomic and transcriptomic analysis of a coniferyl aldehyde-resistant Saccharomyces cerevisiae strain obtained by evolutionary engineering
Authors: Hacısalihoğlu Burcu , Holyavkin Can , Topaloğlu Alican , Kısakesen Halil İbrahim , Çakar Zeynep Petek
Published: March 2019

Phenolic inhibitors in lignocellulosic hydrolysates interfere with the performance of fermenting microorganisms. Among these, coniferyl aldehyde is one of the most toxic inhibitors. In this study, genetically stable Saccharomyces cerevisiae mutants with high coniferyl aldehyde resistance were successfully obtained for the first time by using an evolutionary engineering strategy, based on the systematic application of increasing coniferyl aldehyde stress in batch cultures. Among the selected coniferyl aldehyde-resistant mutants, the highly resistant strain called BH13 was also cross-resistant to other phenolic inhibitors, vanillin, ferulic acid and 4-hydroxybenzaldehyde. In the presence of 1.2 mM coniferyl aldehyde stress, BH13 had a significantly reduced lag phase, which was less than 3 h and only about 25% of that of the reference strain and converted coniferyl aldehyde faster. Additionally, there was no reduction in its growth rate, either. Comparative transcriptomic analysis of a highly coniferyl aldehyde-resistant mutant revealed upregulation of the genes involved in energy pathways, response to oxidative stress and oxidoreductase activity in the mutant strain BH13, already under non-stress conditions. Transcripts associated with pleiotropic drug resistance were also identified as upregulated. Genome re-sequencing data generally supported transcriptomic results and identified gene targets that may have a potential role in coniferyl aldehyde resistance.