bluuebunny/crossref_metadata_2025 huggingface dataset:
Allogenes und autologes Material führt bei Mastoidhöhlenobliteration zu vergleichbaren Rezidivraten
Authors: Weiss Nora , Stallbaum Torben , Botzen Jannik , Bächinger David , Großmann Wilma , Bernd Hans Edgar , Mlynski Robert
Published: May 2021

Einleitung Bei symptomatischen Mastoidhöhlen nach Ohroperationen besteht die Therapie der Wahl in der chirurgischen Verkleinerung. Hierbei stehen verschiedene Methoden und Materialien zur Obliteration zur Verfügung. Allogenes Material ist leicht verfügbar, kann jedoch zu Wundinfektionen aufgrund von Abstoßungsreaktionen, Granulationen und Entzündungsreaktionen führen, weshalb autologes Material aufgrund seiner guten Biokompatibilität häufig bevorzugt wird. Ziel dieser Studie war es, die Langzeitergebnisse von Patienten nach Mastoidhöhlenobliteration mit allogenem und autologem Material im Hinblick auf das Auftreten von Rezidivcholesteatomen, die Anzahl der Revisionsoperationen und den Einfluss der Operation auf die Lebensqualität zu vergleichen.

Methoden Patienten, die sich einer Mastoidhöhlenobliteration mit dem allogenen Material Hydroxylapatit-Matrix (HMM) unterzogen, wurden retrospektiv in die Studie eingeschlossen. In einem prospektiven Studienteil wurden Patienten eingeschlossen, welche sich einer Mastoidhöhlenobliteration mit autologem Rekonstruktionsmaterial (AutoM) unterzogen. Bei allen Patienten wurde neben einer ausführlichen Aktenanalyse eine Reintonaudiometrie durchgeführt und bei der postoperativen Untersuchung das Zürcher Mittelohrinventar (Zurich Chronic Middle Ear Inventory [ZCMEI-21]) zur Erhebung der gesundheitsbezogenen, krankheitsspezifischen Lebensqualität ausgefüllt.

Ergebnisse Insgesamt wurden 22 Patienten mit einem durchschnittlichen Alter von 56,9 Jahren (SD 18,7 Jahre) und HMM (mittleres Nachuntersuchungsintervall: 88,3 Monate; SD 21,9 Monate) sowie 25 Patienten mit einem Durchschnittsalter von 52,4 Jahren (SD 13,7 Jahre) und AutoM (mittleres Nachuntersuchungsintervall: 13,5 Monate; SD 9,5 Monate) in die Studie eingeschlossen. Die audiologische Revisionsfreiheit lag nach einem Jahr für HMM bei 100% und für AutoM bei 85%. Die Rezidivfreiheit lag nach einem Jahr für HMM bei 95% und für AutoM bei 100%. Die Gruppen unterschieden sich weder hinsichtlich des postoperativen Hörergebnisses noch der postoperativen Lebensqualität.

Diskussion Die Obliteration von Mastoidhöhlen ist eine chirurgische Herausforderung. Es zeigte sich kein relevanter Unterschied zwischen den verwendeten Materialien im Hinblick auf die Rezidivrate, das Hören und die Lebensqualität über den für beide Gruppen beobachteten Zeitraum von 13,5 Monaten. Die oft fehlende subjektive Symptomatik zusammen mit der hohen Rate an Rezidivcholesteatomen und Revisionsindikationen unterstreicht die Notwendigkeit einer regelmäßigen klinischen Nachsorge inklusive der Ohrmikroskopie bei chronischen Mittelohrerkrankungen und lässt regelmäßige Nachuntersuchungen dringend empfehlen.
Validity and Reliability of the German Version of the Locomotor Capabilities Index-5 (LCI-5)
Authors: Ranker Anna Helena , Schäfer Axel , Schöttker-Königer Thomas , Davies-Knorr Trisha , Greitemann Bernhard , Ranker Alexander
Published: May 2021

Background Before foreign language questionnaires, such as patient reported outcome measures (PROMs), can be scientifically used in the national language, guideline-based translation, cultural adaptation and comprehensive verification of their validity and reliability are needed. The aim of this study was to assess the psychometric properties of the German version of the LCI-5 (LCI-5-D) on a sample of people with lower limb amputation (LLA).

Methods The LCI-5 was translated into German (LCI-5-D) based on the ISPOR guidelines for cross-cultural adaptation following pilot testing. The final LCI-5-D was administered to n = 52 lower limb amputees in order to determine the validity and reliability of both the total score and the subscores (“basic items” and “advanced items”). Internal consistency (Cronbachʼs alpha), test-retest reliability (ICC2,1), standard error of the mean (SEM), minimal detectable change (MDC), item-to-total correlation, and item-to-subscale correlation were calculated. Floor and ceiling effects were checked. For construct validity, the Rivermead Mobility Index (RMI) and timed up and go (TUG) test were correlated, and differences of defined subgroups (amputation height and prosthesis user type) were calculated.

Results On average, the score of the LCI-5-D was 40.13 ± 16.64 points. High ceiling effects were present for the subscale “basic items” (57.7% maximum score). Internal consistency showed excellent results (Cronbachʼs α = 0.97). A strong correlation to the RMI (r = 0.863; p < 0.001) and to the TUG (r = − 0.714; p < 0.001) demonstrated construct validity. Test-rest reliability was measured after an averaged time span of 5.3 ± 2.47 days and resulted in very high reliability [ICC (2,1) = 0.97; p < 0.001]. MDC was 7.57 points for the total score.

Conclusion The LCI-5-D is a valid and reliable PROM for measuring mobility with prostheses in German-speaking lower limb amputees, which is rather suitable for people with low to moderate mobility abilities. It can be used in a German-speaking population.
A Clinicoradiological Assessment following Surgical Intervention in Patients of Cervical Spondylotic Myelopathy: An Institutional Experience
Authors: Gill Maneet , Maheshwari Vikas , Yadav Arun Kumar , Gadhavi Rushikesh
Published: May 2021

Introduction To critically analyze the functional and radiological improvement in patients of cervical spondylotic myelopathy (CSM) who underwent surgical decompression by an anterior or posterior approach.

Materials and Methods A retrospective study was conducted in a tertiary-level Armed Forces Hospital from June 2015 to December 2019. Preoperative assessment included a thorough clinical examination and functional and radiological assessment. The surgical decompression was done by an anterior or a posterior approach with instrumented fusion. Anterior approach was taken for single or two-level involvement and posterior approach for three or more cervical levels. The pre and postoperative neurological outcome was assessed by Nurick and modified Japanese Orthopaedic Association (mJOA) score along with measurement of canal diameter and cross-sectional area.

Results A total of 120 patients of CSM who underwent surgical decompression were analyzed. Both the groups were comparable and had male predominance. A total of 59 patients underwent surgical decompression by an anterior approach and the remaining 61 patients by the posterior approach. Out of the 59 patients operated by the anterior approach, 30 (50.85%) underwent anterior cervical discectomy and fusion (ACDF); remaining 29 (49.15%) underwent anterior cervical corpectomy and fusion (ACCF). In the posterior group (n = 61), 26 (42.6%) patients underwent laminoplasty and the remaining 35 (57.4%) underwent laminectomy with or without instrument fusion. Sixteen patients out of these underwent lateral mass fixation and the remaining 19 underwent laminectomy. There was functional improvement (mJOA and Nurick grade) and radiological improvement in both subgroups, which were statistically significant (p < 0.0001).

Conclusion A prompt surgical intervention in moderate-to-severe cases of CSM either by the anterior or the posterior approach is essential for good outcome.
Effect of Nosodes on Lettuce, Parasitized or Not by Meloidogyne enterolobii
Authors: Ferreira Thais Moraes , Mangeiro Mariana Zandomênico , Almeida Alexandre Macedo , Almeida Rafael N. , Souza Ricardo Moreira
Published: May 2021

Background Nosodes are homeopathic preparations (HPs) obtained from tissues or substances associated with the targeted disease or from culture of the pathogenic agent. Nosodes are thought to modulate host resistance, easing symptoms or promoting cure. A few studies have been published about control of plant-parasitic nematodes with HPs, but none with nosodes. Conceptually, nosodes prepared from nematode infective stages might interact with the plant's pathogen-recognition system and initiate or modulate plant resistance to nematodes.

Objective Our goal was to investigate whether nosodes prepared from second-stage juveniles (J2) of Meloidogyne enterolobii can affect the moderate resistance already existing in the lettuce cultivar ‘Elisa’.

Methods Nosodes at the Hahnemannian concentrations (cH) 6, 18, 30 and 42 were applied on lettuce plants through irrigation, with a constant daily dosage. The nosode treatment started at the seedling stage, before nematode inoculation with 3,000 eggs + J2 per plant. A series of absolute and relative controls, and 10 replicates per treatment, were employed. At harvest, variables related to plant growth and nematode reproduction were assessed.

Results The nosode at 6, 18, and 30cH reduced (p <0.05) the nematode reproduction factor and root density. The nosode effect was cH-dependent since nematode reproduction was favored by treatment with 42cH. The nosode also affected (p <0.05) lettuce roots, which presented higher or lower fresh weight and volume depending on the cH applied and the condition—parasitized or not.

Conclusion Nosodes obtained from Meloidogyne J2 may affect plant parasitism by nematodes, possibly by interfering with plant resistance. The nature—positive or negative—and intensity of the nosode effect depends on the cH applied to the plants. Further studies are necessary to identify which cH values are more effective in reducing nematode reproduction without causing negative side effects on plant growth.
A Preliminary Model of the Wrist Midcarpal Joint
Authors: Pendola Martin , Petchprapa Catherine , Wollstein Ronit
Published: May 2021

Background A challenge to deciphering the effect of structure on function in the wrist involves difficulty in obtaining in-vivo information. To provide a platform to study wrist mechanics using in vivo acquired forces, we developed a model of the midcarpal joint based on computed tomography (CT) scans of normal wrists. Finite element analysis (FEA) can enable application of in vivo collected information to an ex vivo model.

Objectives The objectives of this study are to (1) create a three-dimensional model of the midcarpal joint of the wrist based on CT scans and (2) generate separate models for the midcarpal joint based on two distinct wrist types and perform a pilot loading of the model.

Methods CT scans from a normal patient database were converted to three-dimensional standard template library (STL) files using OsiriX software. Five type 1 and five type 2 wrists were used for modeling. A simulated load was applied to the carpometacarpal joints in a distal-to-proximal direction, and FEA was used to predict force transfer in the wrist.

Results There were 33% type 1 and 67% type 2 wrists. The midcarpal joint dimensional measurements estimated from the model had intermediate agreement between wrist type as measured on CT scan and as predicted by the model: 56% Cohen's kappa (95% confidence interval) = 0.221 (0.05–0.5). Surface stress on the carpometacarpal joints is different in type 1 and type 2 wrists. On loading the neutral wrist, the capitolunate angle was 90 degrees in type 1 wrists and 107 degrees in type 2 wrists (p < 0.0001).

Conclusions The model predicted differences in movement and force transfer through the midcarpal joint dependent on structural type. This knowledge can improve our understanding of the development of disparate patterns of degeneration in the wrist.
Development of a Novel Recurrent Gastrointestinal Bleeding Model in Swine for Provocative Mesenteric Angiography
Authors: Stewart Jessica K. , Perkins Scott S. , Cline Brendan , Kim Charles Y.
Published: May 2021

Purpose The purpose of this study was to develop a novel swine model of recurrent gastrointestinal bleeding that could potentially be utilized for the study of provocative mesenteric angiography.

Methods Animal experiments were approved by the Institutional Animal Care and Use Committee. The superior mesenteric artery was catheterized via percutaneous transfemoral access. Via laparotomy, multiple small incisions were created in the small bowel wall of four swine. After hemostasis was achieved, varying amounts of thrombolytics were infused into the superior mesenteric artery via a 5 french catheter. The number of incisions with observable rebleeding and interval until rebleeding were ascertained.

Results In a test animal, active extravasation was confirmed to be detectable on digital subtraction angiography at a small bowel incision site. After tissue plasminogen activator (tPA) administration into the superior mesenteric artery, rebleeding from the incisions was visually observed in 11 of 30 small bowel incisions (37%). Provoked bleeding occurred at a median of 6 minutes (mean: 5 minutes and 52 seconds) after completion of tPA injection with a range of approximately 1 to 10 minutes.

Conclusion This pilot study proposes a feasible model for provocative mesenteric angiography in swine.
The Accuracy of Computed Tomography-Based, Three-Dimensional Implant Planning in Robotic-Assisted Total Knee Arthroplasty
Authors: Marchand Kevin B. , Salem Hytham S. , Mathew Kevin K. , Harwin Steven F. , Mont Michael A. , Marchand Robert C.
Published: May 2021

Advanced imaging used in robotic-assisted total knee arthroplasty (TKA), such as computed tomography (CT)-based three-dimensional (3D) planning, may provide an accurate means of implant sizing preoperatively. The purpose of this study was to examine preoperative CT-based implant planning accuracy for robotic-assisted TKA in patients who have (1) varus deformities, (2) valgus deformities, (3) neutral alignment, and (4) retained hardware. A total of 393 patients underwent a robotic-assisted TKA by a single surgeon received preoperative CT scans. The surgeon reviewed the CT-based model preoperatively and recorded the expected size of the components. The final implants used in each case were recorded and compared with the surgeon's preoperative plan. In all groups of patients, the surgeon's CT-based implant plan was within one size of the implant utilized 100% of the time for both the tibiae and femora. Overall, the surgeon was exactly matched in 319 (81%) and 315 (80%) cases for the femoral and tibial components, respectively. For the femoral component, the mean age for patients in whom the original plan was exactly matched was younger than those whose implants were upsized and older than patients those implants were downsized (p = 0.024). Other patient demographics and preoperative knee alignment were not associated with predictive accuracy for femoral or tibial components. Our results demonstrate how preoperative CT-based, 3D planning for robotic-assisted TKA is accurate to within one size of the components in every case (100%), and exactly matched in 80%. The results of this study are important because they demonstrate how CT-based preoperative implant planning for TKA is reliable and accurate across all native knee alignments and other patient-specific factors. In addition, they build on a previous study by the same single surgeon, demonstrating that predictive ability can improve over time. This may be important as we move toward more outpatient surgery with less ability for prostheses inventory at ambulatory sites.
Personal values in mental disorders: an exploratory analysis
Authors: Socci Valentina , Talevi Dalila , Stratta Paolo , Rossi Alessandro , Pacitti Francesca , Lucaselli Alessia , Gregori Eleonora , Quarta Eleonora , Rossi Rodolfo
Published: May 2021

Personal values have increasingly become central in socio-psychological research. However, the relationships between values and psychopathological variables have been scarcely investigated, with mixed results. This study aimed to explore potential differences in value orientation in a sample of people with psychotic disorders and mood disorders compared to a non-clinical sample using the Schwarz’s values framework. A clinical sample of 162 subjects (92 subjects with psychotic disorders and 70 with mood disorders) and a non-clinical sample of 217 subjects completed the self-report measures of affective states (PANAS) and personal values (PVQ). Irrespective of the diagnostic group, the clinical sample showed higher expression of Conservation values (i.e., Tradition, Conformity, Security). Conservation and Self-enhancement values positively correlated with PANAS-positive affectivity in the clinical sample; in the non-clinical sample, Self-enhancement values only correlated with PANAS-positive affectivity. The expression of Conservation values in individuals with a mental disorder could reflect an orientation toward Conformity underlying fundamental affiliative goals. The complex relationship between personal values and clinical constructs should be further investigated, with important theoretical and clinical implications in mental health.
Localized strain profile in surface electrode array for programmable composite multiferroic devices
Authors: Xiao Zhuyun , Lai Chelsea , Zheng Ruoda , Goiriena-Goikoetxea Maite , Tamura Nobumichi , Juarez Cornelio Torres , Perry Colin , Singh Hanuman , Bokor Jeffrey , Carman Gregory P. , Candler Rob N.
Published: May 2021

We investigate localized in-plane strains on the microscale, induced by arrays of biased surface electrodes patterned on piezoelectrics. Particular focus is given to the influence that adjacent electrode pairs have on one another to study the impact of densely packed electrode arrays. We present a series of X-ray microdiffraction studies to reveal the spatially resolved micrometer-scale strain distribution. The strain maps with micrometer-scale resolution highlight how the local strain profile in square regions up to 250 × 250 μm2 in size is affected by the surface electrodes that are patterned on ferroelectric single-crystal [Pb(Mg1/3Nb2/3)O3]x-[PbTiO3]1−x. The experimental measurements and simulation results show the influence of electrode pair distance, positioning of the electrode pair, including the angle of placement, and neighboring electrode pair arrangements on the strength and direction of the regional strain. Our findings are relevant to the development of microarchitected strain-mediated multiferroic devices. The electrode arrays could provide array-addressable localized strain control for applications including straintronic memory, probabilistic computing platforms, microwave devices, and magnetic-activated cell sorting platforms.
An effect of crystallographic distortion on carrier mobility in poly(3-hexylthiophene) thin films
Authors: Abe Tatsuki , Kawaguchi Daisuke , Watanabe Motonori , Hoshino Taiki , Ishihara Tatsumi , Tanaka Keiji
Published: May 2021

The aggregation states and physical properties of polymers in thin films deviate from those found in the bulk. Although an effect of the thickness on the carrier mobility for thin films of poly(3-hexylthiophene) (P3HT) has been widely studied, there is a lack of discussion in terms of crystallographic distortion. Here, we demonstrate how the out-of-plane hole mobility in P3HT, which is a typical semiconducting polymer, changes with decreasing film thickness. Time-of-flight measurements with an analysis using the Gaussian disorder model revealed that the zero-field out-of-plane hole mobility decreased with decreasing thickness because of an increase in the energetical and spatial distribution of hopping sites. Grazing incidence wide-angle x-ray diffraction measurements revealed that such distributions of charge carriers were induced by the crystallographic distortion of P3HT in the thin films.
Leakage current characteristics and DC resistance degradation mechanisms in Nb doped PZT films
Authors: Akkopru-Akgun Betul , J. M. Thorsten , Tsuji Kosuke , Wang Ke , Randall Clive A. , Lanagan Michael T. , Trolier-McKinstry Susan
Published: May 2021

The correlation between defect chemistry, leakage currents, and time-dependent dielectric breakdown was studied for PbZr0.52Ti0.48O3 (PZT) films doped with 0.5, 1, 2, or 4 mol. % Nb. As the samples are nearly intrinsic (that is, close to n- to p-type transition), signatures for both hole hopping between Pb2+ and Pb3+ and electron trapping by Ti4+ were observed. For all doping levels, the dominant conduction mechanism transitioned from Poole–Frenkel emission at lower electric fields to Schottky emission at higher electric fields. The electric field for this transition diminishes from 172 to 82 kV/cm with decreasing Nb concentration. The concomitant modification of the Schottky barrier height from 1.24 to 0.95 eV with decreasing Nb concentration is attributed to Fermi level pinning via oxygen vacancies. The DC resistance degradation was controlled by Schottky emission from 250 to 400 kV/cm. It was found that the lifetime of the films increases with increasing the Nb level. The effective Schottky barrier height for 2 mol. % Nb-doped PZT films decreased from 1.12 to 0.85 eV during degradation. This is related to the movement of oxygen vacancies toward the cathode and the observation of Ti3+ near the cathode, which are proved via thermally stimulated depolarization current and electron energy loss spectroscopy, respectively. Furthermore, Schottky emission starts to control the conduction at lower electric fields after degradation as a result of oxygen vacancy accumulation near the cathode. This, in turn, decreases the potential barrier height for electron injection from the Pt electrode into the PZT films. The mechanisms for time-dependent dielectric breakdown in PZT films will thus be a strong function of the initial oxygen vacancy concentration and its distribution within the PZT films.
Rational construction of staggered InGaN quantum wells for efficient yellow light-emitting diodes
Authors: Zhao Xiaoyu , Tang Bin , Gong Liyan , Bai Junchun , Ping Jiafeng , Zhou Shengjun
Published: May 2021

High-efficiency InGaN-based yellow light-emitting diodes (LEDs) with high brightness are desirable for future high-resolution displays and lighting products. Here, we demonstrate efficient InGaN-based yellow (∼570 nm) LEDs with optimized three-layer staggered quantum wells (QWs) that are grown on patterned sapphire substrates. Numerical simulations show that the electron–hole wavefunction overlap of staggered InGaN QWs with high In content exhibits a 1.7-fold improvement over that of square InGaN QWs. At the same injection current, LEDs with staggered QWs exhibit lower forward voltages and narrower full widths at half maximum than LEDs with square QWs. The light output power and external quantum efficiency of a staggered QW LED are 10.2 mW and 30.8%, respectively, at 15 mA. We combine atomic probe tomography (APT), time-resolved photoluminescence (TRPL), and transmission electron microscopy (TEM) with energy-dispersive x-ray (EDX) mapping spectroscopy to shed light on the origin of enhanced device performance. APT results confirm the staggered In profile of our designed staggered QWs structure, and TRPL results reveal decreased defect-state carrier trapping in staggered QWs. Furthermore, TEM with EDX mapping spectroscopy supports the viewpoint that staggered QWs exhibit uniform elemental distribution and improved crystal quality. Together, these factors above contribute to enhanced LED performance. Our study shows that staggered InGaN QWs provide a promising strategy for the development of LEDs that are efficient in the long-wavelength region.
Particle transport constraints via Bayesian spectral fitting of multiple atomic lines
Authors: Sciortino F. , Cao N. M. , Howard N. T. , Marmar E. S. , Rice J. E.
Published: May 2021

Optimized operation of fusion devices demands detailed understanding of plasma transport, a problem that must be addressed with advances in both measurement and data analysis techniques. In this work, we adopt Bayesian inference methods to determine experimental particle transport, leveraging opportunities from high-resolution He-like ion spectra in a tokamak plasma. The Bayesian spectral fitting code is used to analyze resonance (w), forbidden (z), intercombination (x, y), and satellite (k, j) lines of He-like Ca following laser blow-off injections on Alcator C-Mod. This offers powerful transport constraints since these lines depend differently on electron temperature and density, but also differ in their relation to Li-like, He-like, and H-like ion densities, often the dominant Ca charge states over most of the C-Mod plasma radius. Using synthetic diagnostics based on the AURORA package, we demonstrate improved effectiveness of impurity transport inferences when spectroscopic data from a progressively larger number of lines are included.
Deformation mechanisms in hexagonal close-packed high-entropy alloys
Authors: Wang Z. , Bao M. L. , Wang X. J. , Liaw P. K. , Guo R. P. , Qiao J. W.
Published: May 2021

Single-phase hexagonal close-packed structure of the ScYLaGdTbDyHoErLu high-entropy alloy was studied in detail. The applicability of the rule of mixture was analyzed with respect to the lattice constant, mechanical parameters, elastic properties, melting point, and hardness of the alloy. Significant tension-compression asymmetry has been found and explained by the strength differential effect during the uniaxial tests. Numerous deformation twins and high densities of stacking faults can be observed from the morphological characterization by a transmission electron microscope, which governs the main deformation mechanism during the plastic deformation in the current high-entropy alloy.
Bubble cloud configuration effect on the added mass
Authors: Zoghlami S. , Béguin C. , Teyssedou A. , Scott D. , Bornard L. , Etienne S.
Published: May 2021

Understanding the mechanisms that control the dynamics of bubble clouds is essential to many industrial processes in the energy and chemical realms. Due to the complexity of the two-phase flow configurations, modeling the physics of the phenomena driving the mixing of bubbles within a liquid matrix is still a major challenge. One of the weaknesses of most existing two-phase flow models is due to the incomplete handling of bubble dispersion. This difficulty comes from the fact that dispersion can be driven by numerous complex phenomena, such as turbulence, local pressure distribution, bubble to bubble interaction, etc. In this study, we introduce the effect of added mass fluctuations on the dispersion of small bubbles. Existing models based on the Euler–Euler approach do not take into account local flow variations due to bubble distributions. Therefore, these models do not correctly describe fine dispersion features. Solving the potential flow around N bubbles allows to take into account the effect of the added mass on bubble cloud distributions. To this aim, a complete added mass model, which includes local bubble configurations via the void fraction gradient, is developed. The void fraction gradient allows us to account for the asymmetry of the bubble cloud around a single central bubble. Consequently, the proposed model can only represent regular and irregular bubble cloud distributions. This methodology results in a more consistent consideration of the added mass effects as well as Meshchersky's force, which should be included in hydrodynamic two-phase flow models. The proposed approach can be implemented in Euler–Euler models intended to consider the dispersion of bubbles caused by the effect of added mass.
On the quantum and classical control of laser-driven isomerization in the Wigner representation
Authors: Petersen Jens , Einsele Richard , Mitrić Roland
Published: May 2021

We investigate the validity of the classical approximation to the numerically exact quantum dynamics for infrared laser-driven control of isomerization processes. To this end, we simulate the fully quantum mechanical dynamics both by wavepacket propagation in position space and by propagating the Wigner function in phase space employing a quantum-mechanical correction term. A systematic comparison is made with purely classical propagation of the Wigner function. On the example of a one-dimensional double well potential, we identify two complementary classes of pulse sequences that invoke either a quantum mechanically or a classically dominated control mechanism. The quantum control relies on a sequence of excitations and de-excitations between the system’s eigenstates on a time scale far exceeding the characteristic vibrational oscillation periods. In contrast, the classical control mechanism is based on a short and strong few-cycle field exerting classical-like forces driving the wavepacket to the target potential well where it is slowed down and finally trapped. While in the first case, only the quantum mechanical propagation correctly describes the field-induced population transfer, the short pulse case is also amenable to a purely classical description. These findings shed light on the applicability of classical approximations to simulate laser-controlled dynamics and may offer a guideline for novel control experiments in more complex systems that can be analyzed and interpreted utilizing efficient state-of-the-art classical trajectory simulations based on ab initio molecular dynamics.
Liquid metallic laser ultrasound transducer for high-temperature applications
Authors: Kim Howuk , Kim Kyunghoon , Garcia Nicholas , Fang Tiegang , Jiang Xiaoning
Published: May 2021

This study aims to investigate a laser ultrasound (LUS) transducer for high-temperature (>100 °C) applications. For decades, many researchers have investigated efficient LUS transducers, yet studies on laser ultrasound transducers capable of performing at the high-temperature condition are rarely found in the literature. Most current LUS transducers still utilize a polymer-based composite material, that is, not stable at varying temperature conditions. This study introduces a liquid metallic (LM) LUS transducer that utilizes field's metal, which has a high thermal expansion (∼3 × 10−4 K−1). We hypothesized that such a high thermal expansion of the liquid metal can effectively produce laser-generated ultrasound waves, substituting for conventional polymer-based transducers. A numerical simulation predicted that the LM LUS transducer would produce higher LUS intensity (∼22 dB) than that without the LUS transducer. Experiment results confirmed that the LM transducer effectively intensifies the ultrasound wave signals, obtaining a signal-to-noise gain over 30 dB. Moreover, the transducer was found capable of transmitting detectable wave packets in relatively high-temperature conditions (∼400 °C), while conventional candle soot nanoparticle-polydimethylsiloxane could not perform stably at these elevated temperatures. The investigations introduced in this article are scientifically significant since we demonstrated the engineering feasibility of liquid metallic materials for LUS transducers.
Positron Scattering from the Group IIB Metals Zinc and Cadmium: Recommended Cross Sections and Transport Simulations
Authors: Stokes P. W. , White R. D. , McEachran R. P. , Blanco F. , García G. , Brunger M. J.
Published: May 2021

Results from the application of our optical potential and relativistic optical potential models to positron scattering from gas-phase zinc (Zn) and cadmium (Cd) are presented. In particular, integral cross sections (ICSs) for elastic scattering, positronium formation, summed discrete electronic-state excitation, and ionization scattering processes are reported for both species and over an extended incident positron energy range. From those ICSs, the total cross section is subsequently constructed by taking their sum. We note that there are currently no experimental data available for any of these scattering processes for either species, with earlier computational results being limited to the elastic channel and restricted to relatively narrow incident positron energy regimes. Nonetheless, we construct recommended positron cross section datasets for both zinc and cadmium over the incident positron energy range of 0–10 000 eV. The recommended positron cross section data are subsequently employed in a multi-term Boltzmann equation analysis to simulate the transport of positrons, under the influence of an applied (external) electric field, through the background Zn and Cd gases. Qualitatively similar behavior in the calculated transport coefficients was observed between both species. Finally, for the case of zinc, the present positron transport coefficients are compared against corresponding results from electron transport with some significant differences now being observed.
Prediction and experimental verification of erosion resistance of gas switch electrode materials
Authors: Luo Cheng , Cong Peitian , Zhang Tianyang , Zhong Xiangli , Luo Weixi
Published: May 2021

The gas spark switch is the most used key device in pulsed power systems. As a difficult problem affecting the performance of the gas spark switch, electrode erosion has always been of wide concern and has been studied by scholars. In order to reduce electrode erosion, the erosion resistance of the electrode materials is particularly critical. At present, researchers at home and abroad mainly perform a large number of experiments to compare the erosion resistance of different electrode materials, which require a lot of time and are expensive. Based on the theoretical derivation of the erosion heat conduction process and the analysis of the molten pool movement process, a theoretical prediction model of erosion resistance of electrode materials is established in this paper. The prediction results of this model are consistent with the experimental results of most researchers in the past. In order to further verify the accuracy of this model, this paper selected six electrode materials [stainless steel, brass, RHEAs (Refractory High Entropy Alloys), 90WCu alloy, 70WCu alloy, and 50WCu alloy] tested for 10 000 times under the experimental conditions of a peak current of 30 kA, a single discharge charge transfer of 78 mC, and 2 bars dry air. The final experimental results show that the six electrode materials ranked from weak to strong in erosion resistance: brass, stainless steel, 50WCu, 70WCu, RHEAs, and 90WCu, which is consistent with the prediction results of the model.
Cell-phone camera Raman spectrometer
Authors: Dhankhar Dinesh , Nagpal Anushka , Rentzepis Peter M.
Published: May 2021

In this report, we describe the design, construction, and operation of a cell-phone-based Raman and emission spectral detector, which when coupled to a diffraction grating and cell-phone camera system provides means for the detection, recording, and identification of chemicals, drugs, and biological molecules, in situ by means of their Raman and fluorescence spectra. The newly constructed cell-phone spectrometer system was used to record Raman spectra from various chemicals and biological molecules including the resonance enhanced Raman spectra of carrots and bacteria. In addition, we present the quantitative analysis of alcohol–water Raman spectra, performed using our cell-phone spectrometer. The designed and constructed system was also used for constructing Raman images of the samples by utilizing a position scanning stage in conjunction with the system. This compact and portable system is well suited for in situ field applications of Raman and fluorescence spectroscopy and may also be an integrated feature of future cell-phones.
Optical image reconstruction in 4f imaging system: Role of spatial coherence structure engineering
Authors: Shen Yuechen , Sun Hu , Peng Deming , Chen Yahong , Cai Qilin , Wu Dan , Wang Fei , Cai Yangjian , Ponomarenko Sergey A.
Published: May 2021

We examine the effect of spatial coherence on the image quality of a classic 4f imaging system when its Fourier plane is partially blocked by an opaque obstacle. We find that although reducing the degree of spatial coherence of the source results in the improved image quality, the concurrent distortions in the image plane are inevitable. Employing a suitable decomposition of a partially coherent light source into a set of coherent pseudo-modes with a multitude of linear phase shifts, we demonstrate that the distortions are primarily induced by the modes whose maxima are located at the obstacle edges. We show that by tailoring spatial coherence of the source we can enable all the coherent modes to circumnavigate the obstacle, ensuring the same image quality as if the obstacle were absent from the Fourier plane. We expect our findings to be instrumental in high-contrast optical microscopy with coherence structured light.
Electrostatic potential measurement at the Pt/TiO2 interface using electron holography
Authors: Nakajima Hiroshi , Tanigaki Toshiaki , Toriyama Takaaki , Yamamoto Mahito , Tanaka Hidekazu , Murakami Yasukazu
Published: May 2021

The interface of Pt/TiO2 plays an essential role in device engineering and chemical reactions. Here, we report the electrostatic potential distribution of a Pt/TiO2 interface by electron holography. The decrease in the electrostatic potential exists at TiO2 in the vicinity of the interface, indicating the presence of negative charge due to electron transfer from TiO2 and Pt. The decrease in the electrostatic potential can be understood in the difference in work functions between Pt and TiO2. This study reveals the interplay between Pt and TiO2 and the usefulness of electron holography for probing the potential in nanoscale interfaces.
Experimental study on the effects of physical conditions on the interaction between debris flow and baffles
Authors: Yang Haiqing , Emdadul Haque Md. , Song Kanglei
Published: May 2021

The gravitational debris flow, such as the agent forming alluvial cones in the mouths of mountain canyons, could bring about devastating disaster to downstream structures in mountainous areas. In the present study, a series of model tests were conducted on the sand and the ceramsite to systematically explore the interaction between debris flow and baffles. During the runout process, the impact force exerted by debris flow was measured by dynamometers. The runout distance, velocity of the flow, and flow depth were monitored by a video camera and a high-speed camera in a real time. The dynamic interaction under different particle sizes of dry granular materials, slop angles, and baffle configurations was simulated. Experimental results show that the smaller size material is favorable for the frictional energy dissipation during the sliding process, giving rise to the smaller runout distance. The present findings provide important references for the debris flow control engineering.
Acoustic response of turbulent cavity flow using resolvent analysis
Authors: Liu Qiong , Gaitonde Datta
Published: May 2021

Fluid–acoustic interactions are important in a variety of applications and typically result in adverse effects. We analyze the influence of Mach number on such interactions and their input–output characteristics by combining resolvent analysis with Doak's momentum potential theory. The specific problem selected is the flow over an open cavity of L∕D = 6 at Re = 10 000 and M∞ = 0.6 and 1.4, respectively. The resolvent forcing and response modes are decomposed into their hydrodynamic, acoustic, and thermal components. Although the results depend quantitatively on Mach number, some trends remain consistent. In particular, at lower frequencies, the acoustic component appears primarily at the trailing edge of the cavity. When the frequency is increased, the acoustic response moves toward the leading edge and overlaps with its hydrodynamic component. Inspired by actual cavity flow control, the forcing is then localized to two regions—the leading edge and front wall of the cavity—and filtered to consider notional actuators that can separately introduce each component of velocity, density, and temperature forcing, respectively. Among these different types of actuation perturbations, regardless of Mach number, streamwise velocity forcing achieves the largest energy amplification at the leading edge. For both flows, beyond a certain forcing frequency threshold value, the nature of the acoustic vs hydrodynamic response becomes independent of the forcing type; however, the amplification continues to be strongly impacted by the forcing frequency. The present work provides an alternative approach to examine input–output flow–acoustic characteristics and evaluate the relative effectiveness of different types and locations of actuation.
Soap film on two noncircular frames
Authors: Alimov Mars M. , Bazilevsky Alexander V. , Kornev Konstantin G.
Published: May 2021

The classical Plateau problem of finding minimal surfaces supported by two noncircular coaxial rings is studied theoretically and experimentally. Using a fluid dynamics analogy, we generalize the classical catenoid solution for a film on circular rings to the general cases of noncircular rings. Some examples of analytical solutions for elliptical, polygonal, and ovoidal rings are presented. The shapes of a tubular film and a film separated by a lamella at the wrist are obtained in an analytical form. The stability of these films is analyzed and compared with the classical catenoid. The data on critical parameters of all minimal surfaces are collected in the tables that can be used in practical applications. The theory is experimentally validated using soap films on elliptical identical frames. Moreover, the shapes of soap films on two different elliptical frames demonstrate a new feature: a flat separating lamella lying parallel to the rings was never observed in experiments. All lamellae appeared deformed suggesting the existence of a new family of minimal surfaces which does not exist in the case of frames of the same sizes.
An efficient approach to achieve flame acceleration and transition to detonation
Authors: Li Tao , Wang Xiaohan , Xu Baopeng , Kong Fanfu
Published: May 2021

This paper presents a novel method to accelerate flame propagation and transition to detonation in a coiled channel. The objective is to bring to light the basic understanding of the phenomenon and to show its potential in the fields of highly efficient combustion or propulsion. It was found that the flame evolution in the coiled channel is significantly different from that in a straight channel. In the flame acceleration stage, the flame propagation velocity increases exponentially in the coiled channel while it increases linearly in the straight channel, primarily due to the existence of a strong velocity gradient in the transverse direction in the coiled channel. Deflagration to detonation transition (DDT) was only observed in the coiled channel under current settings, being triggered by a series of local explosions at the boundary layer. In general, the coiled channel can greatly accelerate the flame and shorten the distance of the DDT compared with the straight channel.
Nonvolatile magnetic half adder combined with memory writing
Authors: Lu Ziyao , Xiong Chengyue , Mou Hongming , Luo Zhaochu , Fang Chi , Wan Caihua , Wu Huaqiang , Zhang Xixiang , Zhang Xiaozhong
Published: May 2021

With the rapid development of modern computers, problems caused by the performance gap between processor and memory in von-Neumann architecture have become significant. Spintronic devices, benefitting from the potential of achieving in-memory computing, have become one of the most competitive candidates to bridge the performance gap. Great efforts have been made to realize the functions of modern computers using spintronic devices. Here, a nonvolatile magnetic arithmetic logic device working at room temperature based on coupling of anomalous Hall effect of Ta/CoFeB/MgO multilayers with perpendicular magnetic anisotropy and elements with negative differential resistance characteristics has been proposed. Logic function of half adder has been experimentally demonstrated. This device could perform the arithmetic logic function of half adder and simultaneously write the computation result in storage bits in the process of performing logic operation. It has the potential to bridge the gap between arithmetic logic units and memory in modern computers.
Characters of frequency response in a coaxial Bragg structure with tapered-double-sinusoidal grooves operating at 0.35 THz frequency
Authors: Ding Xue-Yong , Su Hong-Rui , Wang Lian-Sheng , Qiang Lei
Published: May 2021

On the basis of ordinary sinusoidal groove structures, an auxiliary sinusoidal distribution with a smaller etching period is superimposed, and a negative-taper is added, on the inner and outer conductor walls to form a coaxial Bragg structure with tapered-double-sinusoidal grooves. Through the FORTRAN software programming simulation experiments, we can see that compared with the ordinary sinusoidal grooves, the bandwidth of the working mode and competition mode gets narrower, the quality factor Q gets greater, the residual side-lobes are also suppressed, and the selectivity of frequency is enhanced when the coaxial Bragg structure adopts the tapered-double-sinusoidal grooves. At the same time, the center resonance frequency point of the competition mode is far away from the working mode, and the bandgap overlap is further separated. However, the reflectivity of the working mode decreases and the reflectivity of the competing mode increases with the increase in the gradient angle. These peculiarities of the negative-tapered-double-sinusoidal groove structure are favorable to construct a cavity with a narrower bandwidth and high quality factor and also are favorable to the mode selectivity.
Quantum fluidic charge density wave transport
Authors: Miller John H. , Suárez-Villagrán M. Y.
Published: May 2021

We discuss charge density wave transport as the periodic flow of a quantum fluid of electron–phonon correlates, viewed as quantum solitons, within the condensate. Pair creation of charged soliton droplets is prevented by their electrostatic energy below a Coulomb-blockade threshold electric field. Above threshold, the quantum fluid flows in drip-like fashion as microscopic entities tunnel coherently from one charging energy macrostate to the next. We summarize the time-correlated soliton tunneling model and compare simulations of coherent oscillations, narrow band noise, and current–voltage characteristics with experiment. We also explore the possibility of collective quantum behavior at room temperature in some materials. Finally, we discuss potential applications in quantum information processing.
Local structural heterogeneity induced large flexoelectricity in Sm-doped PMN–PT ceramics
Authors: Yu Zezong , Wang Zhiguo , Shu Shengwen , Tian Tingfang , Huang Wenbin , Li Chunchun , Ke Shanming , Shu Longlong
Published: May 2021

The recently discovered large flexoelectricity in relaxor ferroelectrics has rekindled considerable research interest. In this paper, several Sm-doped Pb(Mg2/3Nb1/3)O3–xPbTiO3 (PMN–xPT) ferroelectric ceramics were prepared and the relationship between flexoelectricity and PT content was systematically investigated. The largest flexoelectric response (∼550 μC/m) was observed in the Sm-doped PMN–32PT ceramic, which should be accounted for in the reorientation of the polar nanoregions. At room temperature, the flexoelectric response of Sm-doped PMN–32PT ceramic is an order of magnitude higher than that of the parent PMN–PT ceramics and even 50% higher than that of Bi–PMN–32PT ceramic (∼300 μC/m). Such a big increment is directly related to the greater local structural heterogeneity caused by Sm3+ ions into PMN–PT. Therefore, the result presented in this paper verifies that introducing local structural heterogeneity is a feasible approach to achieve ultrahigh flexoelectricity.