bluuebunny/crossref_metadata_2025 huggingface dataset:
Three‐dimensional trajectory tracking of an underactuated AUV based on fuzzy dynamic surface control
Authors: Liang Xiao , Qu Xingru , Wang Ning , Zhang Rubo , Li Ye
Published: October 2019

The three‐dimensional trajectory tracking of an underactuated autonomous underwater vehicle (AUV) under the complex unknowns including model uncertainties and time‐varying disturbances is studied. The reference pitch angle and yaw angle are designed in kinematics, based on the time‐varying reference trajectory. Dynamics controllers are developed by incorporating the first‐order filter into the dynamic surface control (DSC), which simplifies the design process and overcome differential explosion in the traditional backstepping. To reduce the influence of the complex unknowns, an adaptive fuzzy‐based DSC scheme is employed to identify the lumped disturbances with arbitrary accuracy and further enhance system robustness. Lyapunov stability analysis demonstrates that tracking errors are bounded and converge to an arbitrarily small neighbourhood of zero. Finally, simulation studies and comparisons with DSC scheme are carried out to illustrate the effectiveness and superiority of the proposed scheme.
Railway freight transportation liberalization as a solution for improving client services quality
Authors: Krykavskyy Yevhen , Stasiuk Kateryna
Published: October 2019

Scientific approaches for defining liberalization as a priority trend in rail transport development has been generalized. The main liberalization purpose and goals have been revealed and systematized. The international experience in rail freight traffic liberalization has been analyzed and conclusions about its efficiency have been made based on statistical data. The basic prerequisites for performing the reformation of rail freight transport in Ukraine by means of liberalization have been revealed. The existing form of transportation process organization at JSC "Ukraine Railways" has been described. A thorough analysis of statistical data characterizing the operational results of the main railway enterprise in Ukraine has confirmed existing problems in the industry that can be resolved through the liberalization process. A survey has been conducted for the main railway customers and a conclusion based on the obtained results has been made considering liberalization necessity for improving customer service quality. A plan of further actions for freight transport liberalization has been proposed.
Improving the efficiency of road transport companies by optimizing the costs of information and advertising activities
Authors: Nagornyi Yevgen , Shulika Olha , Severyn Oleksandr , Orda Oleksandra
Published: October 2019

In this article, we propose to improve the efficiency of transport companies by managing information and advertising activities to promote material flow. In this research, within the framework of planning the supply of consumer goods in cities, we offer the following alternative supply schemes: the direct goods delivery and delivery through distribution centres. In order to choose a rational supply scheme as a criterion of efficiency it was proposed to use the total delivery cost including the information and advertising component. The research also provides the methodology for determining the maximum effect of advertising activities by road transport companies. In addition, an example of developed advertising packages with the minimum and maximum advertising costs is given. The measures proposed in the research will allow developing a program to stimulate demand for transport services and increase the competitiveness of road transport companies in the transport market.
The development and special aspects of Islamic finance in Europe at the present stage
Authors: Kurochkina Iryna , Us Ulija
Published: October 2019

The article is dedicated to the peculiarities and specificities of Islamic finance in Europe. We considered the prime tools of the Islamic economical system, historical aspects of the Islamic finance appearance in Europe. We also investigated the prospects of implementing and development of Islamic finance in Europe and in Ukraine.
Auswirkungen der Digitalisierung auf Sexualität und Beziehung
Authors: Melzer Heike
Published: October 2019

Gegenstand und Ziel Die digitale Transformation verändert die Sexualität und Beziehungsgestaltung vor allem junger Menschen in vielfältiger Weise.

Material und Methoden Klinische Beobachtungen aus der Praxis der Paar- und Sexualtherapie werden vor dem Hintergrund aktueller Forschungsergebnisse dargestellt.

Ergebnisse Es zeigt sich ein Anstieg sexueller Funktionsstörungen (erektile Dysfunktion, Hemmung oder Ausbleiben des Orgasmus und partnerbezogene Lustlosigkeit) besonders bei jungen Männern. Zudem entstehen zwanghafte oder süchtige Verhaltensweisen um Pornografie und Sexualität sowie sexuelle Abweichungen (Paraphilien) nehmen zu.

Schlussfolgerungen Der problematische und frühzeitige Konsum von starken sexuellen Stimuli (Pornografie, ständig wechselnde sexuelle Partner sowie leistungsstarke Sex-Toys) verursacht neue Probleme und Krankheitsbilder, die nicht genügend erforscht sind. Für wissenschaftlich fundierte präventive, diagnostische und therapeutisch interdisziplinäre Maßnahmen ist diese Forschung dringend erforderlich.

Klinische Relevanz Zur Förderung sexueller Gesundheit und Zufriedenheit müssen neue sexuelle Störungen bzw. problematische Erlebnis- und Verhaltensweisen im digitalen Kontext frühzeitig fachgerecht erkannt, diagnostiziert und therapiert werden.
Psychologische Behandlungsverfahren bei Kopfschmerz
Authors: Dresler Thomas , Klan Timo , Liesering-Latta Eva , Lüpke Johanna , Hubalek Irina , Kraya Torsten , Kropp Peter
Published: October 2019

In diesem Beitrag wird beschrieben, welche psychologischen Behandlungsverfahren in der Therapie von Kopfschmerzerkrankungen eingesetzt werden können. Technologische Entwicklungen in den letzten Jahrzehnten habe neue Möglichkeiten eröffnet, deren Potenzial es allerdings noch genauer auszuloten gilt. Die Idee moderner Kopfschmerztherapie ist nicht der isolierte Einsatz einzelner Verfahren, sondern eine möglichst gute, individuell auf den Patienten zugeschnittene Kombination verschiedener psychologischer Behandlungsverfahren mit anderen medikamentösen und nicht medikamentösen Verfahren. Um für jeden Kopfschmerzpatienten eine maßgeschneiderte Therapie zu ermöglichen, sollte ein interdisziplinäres Vorgehen das Ziel sein.
The Effects of Co-prescription of Pantoprazole on the Clozapine Metabolism
Authors: Kuzin Maxim , Schoretsanitis Georgios , Haen Ekkehard , Dammann Gerhard , Hiemke Christoph , Gründer Gerhard , Paulzen Michael
Published: October 2019

Background Polypharmacy including somatic medications such as proton pump inhibitors is a common phenomenon in psychiatric care. The aim of this study was to evaluate the pantoprazole effects on clozapine metabolism.

Methods A large therapeutic drug-monitoring database containing plasma concentrations of CLZ was analyzed. The results were stratified into four groups: a non-smoking (n=250) and a smoking group (n=326), and two groups co-medicated with pantoprazole: non-smokers (n=26) and smokers (n=29). The analysis was based on the non-parametrical Mann-Whitney U test (M-W-U) with a significance level of 0.05.

Results Differences reached statistical significance for pharmacokinetic parameters between CLZ monotherapy and co-medication with pantoprazole neither in smokers nor in non-smokers (p>0.05 for M-W-U in pairwise comparisons). In patients with clozapine monotherapy, smokers had a higher daily dosage of CLZ compared to non-smokers (mean dosage 363±181 vs. 291±145 mg/day, p<0.001 for M-W-U).

Conclusions Adding pantoprazole to an ongoing treatment with clozapine does not alter the metabolism of clozapine to a significant extent.
Thoracic Renal Artery
Authors: Rossi Umberto G. , Rollandi Gian Andrea
Published: October 2019

We report a case of right renal artery originating from the thoracic aorta with normal position of the right kidney. Although this anomaly is rare, vascular, thoracic, and urological surgeons should be aware about this vascular variant before planning their surgical intervention.
Clinical Characteristics of Patients with Trigeminal Neuralgia Referred to Neurosurgery
Authors: Siqueira Silvia RDT , Teixeira Manoel J , Siqueira José TT
Published: October 2019

Objectives: To investigate the clinical characteristics of patients with trigeminal neuralgia referred to surgery in a center of reference.

Methods: We evaluated the general characteristics of 395 patients with trigeminal neuralgia referred to neurosurgery as treatment. They corresponded to 2 samples of 1984 and 2004. The EDOFHC protocol (Orofacial Pain Questionnaire) and the medical profile were used.

Results: In the first study (1984), with 290 patients, the higher prevalence was: women (57.3%), white (95.5%), with mean age of 62.5. The most affected trigeminal branches were the maxillary and / or mandibular branches (65.5%), and the right side was the most affected (57.6%). From the second study (2004), with 105 patients, 57.1% were women, 75.2% white, with a mean age of 60.8. The maxillary and / or mandibular branches (79.0%) and the right side (69.5%) were the most affected. Both samples had neurological abnormalities and systemic diseases (mainly cardiovascular).

Conclusions: General characteristics of these patients were similar to other samples of trigeminal neuralgia. Neurological findings were also present in patients with no previous surgical treatment for TN. Hypertension and cardiac diseases were also frequent and make the monitoring of the patients during crises necessary. (Eur J Dent 2009;3:207-212)
Perioperative Anemia Management
Authors: Abeysiri Sandaruwani , Chau Marisa , Richards Toby
Published: October 2019

Anemia is increasingly recognized as an interventional hematological target in patients before major surgery. Preoperative anemia increases the need for perioperative blood transfusion, and there is now a well-recognized association with increased patient complications, length of hospital stay, and worse outcomes. Patient Blood Management (PBM) is a World Health Organization endorsed, evidence-based management bundle of care in transfusion hemostasis that focuses on three main aspects: anemia management, prevention of blood loss, and appropriate transfusion practice. Implementation of PBM guidelines has been accompanied by reduced transfusion needs and improved patient outcomes. In a patient presenting with preoperative anemia or at risk of transfusion, this should initiate a program of PBM that manages the patient through the entire operative period. We review the current evidence on the three pillars of PBM and highlight those aspects with the strongest evidence in support of their impact.
Evaluation of Cariogenic Bacteria
Authors: Nishikawara Fusao , Nomura Yoshiaki , Imai Susumu , Senda Akira , Hanada Nobuhiro
Published: October 2019

Objectives : The evaluation of Mutans streptococci (MS) is one of the index for caries risk. DentocultTM and CRTTM are commercial kits to detect and evaluate MS, conveniently. However, the evaluation of MS has also been carried out simply using an instruction manual. But the instruction manual is not easy to use for evaluation of MS. The aim of this study was to examine the utility of modified Mitis-Salivalius Bacitracin (MSB) agar medium compared with MSB agar medium and commercial kits, and to establish a convenient kit (mMSB-kit) using modified MSB agar.

Methods : The MS in stimulated saliva from 27 subjects were detected by MSB, modified MSB agar medium and commercial kits. Laboratory and clinically isolated strains of MS were similarly evaluated. The ratios of MS in detected bacteria were compared by ELISA.

Results : The scores using an mMSB-kit on the basis of modified MSB agar medium were tabulated. Saliva samples showed different levels of MS between culture methods and the commercial kit. Some samples which were full of MS were not detected by the commercial kit. The detection of MS by modified MSB agar medium and mMSB-kit were significantly higher when compared with MSB agar medium, CRTTM, (P< .01) and Dentocult SMTM (P<.05).

Conclusion : The sensitivity for detection of MS is higher for modified MSB agar medium when compared with MSB agar medium. The mMSB-kit can be used simply, and can be an important contributor for the evaluation of MS as a caries risk factor. (Eur J Dent 2007;1:31-39)
The Effect of Luting Agents and Ceramic Thickness on the Color Variation of Different Ceramics against a Chromatic Background
Authors: Azevedo Cubas Gloria Beatriz de , Camacho Guilherme Brião , Demarco Flávio Fernando , Pereira-Cenci Tatiana
Published: October 2019

Objectives: The aim of this study was to assess the influence of various ceramic thicknesses and luting agents on color variation in five ceramic systems. Methods: Fifteen disc-shaped ceramic specimens (11 mm diameter; shade A3) were fabricated with each of the six veneering ceramics tested, with 1, 1.5, or 2 mm thickness (n=5). Resin composite discs (Z-250, shade C4) were used as bases to simulate a chromatic background. The cementation of the veneers was carried out with an opaque resin-based cement (Enforce, shade C4), a resin-based cement (Enforce, shade A3), or without cement (C4, control group). Color differences (ΔE*) were determined using a colorimeter. Three-way ANOVA was used to analyze the data, followed by a Tukey post-hoc test (α=.05). Results: The L*a*b* values of the ceramic systems were affected by both the luting agent and the ceramic thickness (P<.05). In general, there was no difference between the control group and the group using the resin-based cement. The use of an opaque luting agent resulted in an increase of the color coordinates a*, b*, L*, producing differences in ΔE* values for all ceramics tested, regardless of the thickness (P<.05). For the 2-mm thick veneers, higher values in the color parameters were obtained for all ceramics and were independent of the luting agent used. Conclusions: The association of 2-mm thickness with opaque cement presented the strongest masking ability of a dark colored background when compared to a non-opaque Lutinging agent and the other thicknesses tested. (Eur J Dent 2011;5:245-252)
Effect of Occlusal Splints on the Temporomandibular Disorders, Dental Wear and Anxiety of Bruxist Children
Authors: Restrepo Claudia C , Medina Isabel , Isabel Patiñob
Published: October 2019

Objectives: To evaluate the effectiveness of occlusal splints to reduce the signs and symptoms of temporomandibular disorders (TMD), dental wear and anxiety in a group of bruxist children. Methods: All of the subjects were 3 to 6 years old, had complete primary dentition, class I occlusion and were classified as bruxist according to the minimal criteria of the ICSD for bruxism. For each child, anxiety was evaluated with the Conners’ Parent Rating Scales (CPRS). The TMD were evaluated using the RDC/TMD. The dental wear was processed in digital format with Mat Lab® and Lab view® software to determine its size and form. The children were randomized into an experimental (n=19) and a control (n=17) group. The children in the experimental group used rigid bite plates for a two-year period, until mixed dentition. Afterwards, the CPRS and the RDC/TMD were applied again and dental casts were taken. Comparisons of the variables regarding dental wear, signs and symptoms of TMD and anxiety before and after treatment among the groups were analyzed using the t-test, the Wilcoxon rank sum test and the Mann-Whitney test. Results: The subjects in the experimental group showed no statistically significant difference regarding anxiety levels and dental wear when compared with the control group. The signs and symptoms of TMD were not reduced except for the deviation in mouth opening. Conclusions: The use of rigid occlusal bite plates was not efficient in reducing the signs of bruxism as a whole but did reduce the deviation in mouth opening. (Eur J Dent 2011;5:441-450)
Prevention of demineralization around orthodontic brackets using two different fluoride varnishes
Authors: Nalbantgil Didem , Oztoprak Mehmet Oguz , Cakan Derya Germec , Bozkurt Kemal , Arun Tulin
Published: October 2019

Objective: This parallel controlled clinical trial evaluated the effect of a gel containing Lippia sidoides essential oil on plaque and gingivitis control.

Methods: Thirty patients (n=30) were randomly selected and allocated into three groups: Lippia sidoides (LS, n=10), chlorhexidine (CLX, n=10) or placebo (control, n=10). Plaque and bleeding index were recorded at baseline and after three months. All volunteers were instructed to brush with the gel three times a day throughout the experiment period.

Results: There was a significant reduction on plaque and gingivitis in the test groups (P<.05), but no statistically significant difference was observed between them (P<.05).

Conclusion: A gel preparation containing 10% Lippia sidoides essential oil was an efficient herbal antiplaque and antigingivitis agent. (Eur J Dent 2013;7:28-34)
The spatial competition between containerised rail and sea transport in Eurasia
Authors: Lu Mengqiu , Chen Yu , Morphet Robin , Lu Yuqi , Li Enkang
Published: October 2019

The competition in space between rail and sea transport is of great significance to the integration of Eurasia. This paper proposes a land and sea transport spatial balance model for container transport, which can extract a partition line on which transport costs by rail and sea are equal given a destination. Four scenarios are discussed to analyse the effects of different factors on the model. Then the model is empirically tested on current rail and sea transport networks to identify the transport competition pattern in Eurasia. The location of destinations, the freight costs, and time costs are the three main factors affecting the model. Among them, time costs are determined by the value of a container and its contents, the interest rate, and by time differences between land and sea transport. The case study shows that Eurasia forms a transport competition pattern with a land area to sea area ratio of about 1:2; this ratio, however, changes to 1:1 when time costs are considered. Further, the land and sea transport balance lines are consistent with the theories of geopolitics, which indicate that the same processes may exist in the spatial pattern of geo-economics and geopolitics in Eurasia. According to the balance lines, we get a spatial partition, dividing Eurasia into the land transport preferred area, the land–sea transport indifference area, and the sea transport preferred area. The paper brings a new perspective to the exploration of geopolitical economic spatial patterns of Eurasia and provides a practical geographic theory as an analytic basis for the implementation of the Belt and Road Initiative.
Detection and calibration characteristics of the visible and near-infrared imaging spectrometer in the Chang’e-4
Authors: Li C. L. , Xu R. , Lv G. , Yuan L. Y. , He Z. P. , Wang J. Y.
Published: October 2019

Chang’e 4 is a robotic lunar exploration mission operated by the China National Space Administration and was to pull off the first-ever soft landing of space hardware on the mysterious lunar far side. The Visible and Near-IR Imaging Spectrometer (VNIS) is one of the main scientific instruments onboard the Chang’e 4 lunar rover. In order to analyze the lunar surface mineral composition, the VNIS was mounted on the front of the rover and detects lunar objects with a 45° visual angle to obtain spectra and geometry data to make mineralogical and compositional measurements. The VNIS is the same as the one in the Chang’e 3 Yutu rover and consists of a visible and near-infrared imaging spectrometer (0.45–0.95 µm), a shortwave IR spectrometer (0.9–2.4 µm), and a calibration unit with dust-proofing functionality. Here, we describe detection and calibration characteristics of the VNIS, which provides valuable information for scientific data processing and applications.
Null Poynting vector electromagnetic torus
Authors: Tsui K. H. , Arteaga J. A. , Serbeto A.
Published: October 2019

Maxwell equations in free space are solved for a standing wave torus configuration under axisymmetry, which provides a mathematical support to the microwave cavity hypothesis of ball lightning. With a null Poynting vector with the outgoing part canceling the incoming part, this torus configuration satisfies the E→//B→ gauge of the Maxwell equations.
Analysis of fast turbulent reconnection with self-consistent determination of turbulence timescale
Authors: Widmer F. , Büchner J. , Yokoi N.
Published: October 2019

We present results of a Reynolds-averaged turbulence model simulation on the problem of magnetic reconnection. In the model, in addition to the mean density, momentum, magnetic field, and energy equations, the evolution equations of the turbulent cross-helicity W, turbulent energy K, and its dissipation rate ε are simultaneously solved to calculate the rate of magnetic reconnection for a Harris-type current sheet. In contrast to previous studies based on algebraic modeling, the turbulence time scale is self-determined by the nonlinear evolutions of K and ε, their ratio being a time scale. We compare the reconnection rate produced by our mean-field model to the resistive nonturbulent MHD rate. To test whether different regimes of reconnection are produced, we vary the initial strength of turbulent energy and study the effect on the amount of magnetic flux reconnected in time. We obtain that the time scale of turbulence self-adjusts to always produce fast reconnection.
Response of a lead-free borosilicate-glass microchannel plate to 14-MeV neutrons and γ-rays
Authors: Parker C. E. , Frenje J. A. , Siegmund O. H. W. , Forrest C. J. , Glebov V. Yu. , Kendrick J. D. , Wink C. W. , Johnson M. Gatu , Hilsabeck T. J. , Ivancic S. T. , Katz J. , Kilkenny J. D. , Lahmann B. , Li C. K. , Séguin F. H. , Sorce C. M. , Trosseille C. , Petrasso R. D.
Published: October 2019

In microchannel plate applications, such as in space telescopes, night-vision devices, or time-of-flight particle detection, reducing the sensitivity to signals from background sources, such as γ-rays, is beneficial for the system design and performance. The response of a single-stage lead-free borosilicate-glass microchannel plate to 14-MeV neutrons and γ-rays produced via (n, γ) reactions in surrounding structures was investigated at OMEGA. The average efficiency values for secondary electron production were found to be (5.1 ± 0.7) × 10−3 for 14-MeV neutrons and (4.9 ± 1.1) × 10−3 for ⟨1.5⟩-MeV γ-rays.
The effect of crystal anisotropy and plastic response on the dynamic fracture of energetic materials
Authors: Grilli Nicolò , Koslowski Marisol
Published: October 2019

The thermomechanical behavior of solids includes dissipative processes such as plastic deformation and fracture. The relative importance of these processes on the response of energetic materials has been a subject of study for many decades due to their significance on ignition and reaction. However, a constitutive model to simulate the anisotropy of the crack patterns and the effect of plastic deformation due to slip in energetic materials is not yet available. Finite strain thermomechanical constitutive equations that couple crystal plasticity, an equation of state, and an anisotropic phase field damage model are presented. The model is implemented in a multiphysics finite element solver and used to simulate recent experiments on β-HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) by Zaug et al. The simulations reproduce qualitatively the crack pattern and the crystal orientation dependence of the observed damage. Specifically, more damage is observed when the crystal is impacted in the (010) direction, while more plastic deformation is observed when the load is applied in the (110) direction. The present model represents a step forward to understand the interplay between plasticity and fracture in shocked β-HMX single crystals. It can be used to gain insights into temperature increase and hot-spot formation under shock.
Computational fluid radiative dynamics of the Galileo Jupiter entry
Authors: Santos Fernandes L. , Lopez B. , Lino da Silva M.
Published: October 2019

On December 7th, 1995, the Galileo descent probe entered Jupiter’s atmosphere at a relative velocity of 47.4 km s−1. Flight data revealed an unforeseen recession profile: while the stagnation region had been significantly oversized, the shoulder almost completely ablated. In an attempt to understand why numerical predictions diverge from the flight data, several sensitivity studies were performed at the 180 km altitude point. The inaccuracy of the Wilke/Blottner/Eucken model at temperatures above 5000 K was confirmed. When applied to Galileo’s entry, it predicts a narrower shock with higher peak temperatures compared to the Gupta/Yos model. The effects of He and H2 line-by-line radiation were studied. Inclusion of these systems increased radiative heating by 9% at the stagnation point, even when precursor heating is unaccounted for. Otherwise, the internal excitation of H2 due to absorption of radiation originating from the highly emitting shock layer promotes H2 emission before dissociation occurs at the shock, yielding 196% higher radiative heat fluxes. This emphasizes the importance of H2 radiation not only on the recession experienced by Galileo but also for future entries in gas giants. Accordingly, thermal nonequilibrium resulted in 25% lower radiative heating when compared to an equilibrium solution, contrary to previous investigations that neglected H2. Ablation products absorption was shown to counteract the increased emission due to precursor heating of H2. However, the ablation layer temperature must be accurately predicted using a material-response code coupled to the flowfield since radiative heating has been shown to significantly depend on this energy-exchange interaction. Finally, the tangent-slab and ray-tracing models agreed to within 12%.
Instability of nonlinear Trivelpiece-Gould waves I: Wave degeneracies
Authors: Dubin Daniel H. E.
Published: October 2019

Arguments based on energy conservation are used to evaluate the fluid theory of stability of nonlinear traveling waves (pump waves) in an ideal plasma system. Instabilities growing on the pump wave are associated with wave degeneracies. The relative signs of the energies of degenerate waves, as seen in the frame of the pump wave, determine whether their amplitudes grow exponentially or merely oscillate through resonant energy exchange. This energy analysis is carried out in detail for Trivelpiece-Gould (TG) waves and is compared to numerical calculations. It is verified that nonlinear TG waves are stable with respect to 3 wave processes, but weaker 4 wave, 5 wave, and higher order wave processes cause instability over narrow wavenumber bands. A modulational instability is also identified.
Vibrational probe of the origin of singlet exciton fission in TIPS-pentacene solutions
Authors: Grieco Christopher , Doucette Grayson S. , Munson Kyle T. , Swartzfager John R. , Munro Jason M. , Anthony John E. , Dabo Ismaila , Asbury John B.
Published: October 2019

We use native vibrational modes of the model singlet fission chromophore 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pn) to examine the origins of singlet fission in solution between molecules that are not tethered by a covalent linkage. We use the C—H stretch modes of TIPS side groups of TIPS-Pn to demonstrate that singlet fission does not occur by diffusive encounter of independent molecules in solution. Instead, TIPS-Pn molecules aggregate in solution through their TIPS side groups. This aggregation breaks the symmetry of the TIPS-Pn molecules and enables the formation of triplets to be probed through the formally symmetry forbidden symmetric alkyne stretch mode of the TIPS side groups. The alkyne stretch modes of TIPS-Pn are sensitive to the electronic excited states present during the singlet fission reaction and provide unique signatures of the formation of triplets following the initial separation of triplet pair intermediates. These findings highlight the opportunity to leverage structural information from vibrational modes to better understand intermolecular interactions that lead to singlet fission.
Path to turbulence in a transitional asymmetric planar wake
Authors: Hickey Jean-Pierre , Younes Khaled
Published: October 2019

We report on a transitional, high-resolution direct numerical simulation of a temporally developing planar asymmetric wake at Re = 4000 based on the mass flux deficit. The asymmetric wake is formed by a Blasius and a fully turbulent boundary layer on either side of an infinitely thin splitter plate. Such a setup has direct relevance in low-Reynolds number aeronautics where pressure gradients on an airfoil can relaminarize transitional wall-bounded flows, thus generating a half-laminar/half-turbulent wake. The spreading and normalized turbulence intensity of the asymmetric wake are lower than the initially fully laminar wake but greater than the initially turbulent wake. In the far-field, the flow reaches a fully symmetric and nearly self-similar state with a high level of structural organization, originating from the transition of the laminar side. The structures are generated by the mutual interaction of the turbulent/laminar half-wakes. A forcing from the turbulent side accelerates the development of spanwise-organized structures on the laminar side, which evolve and develop a high-level of spanwise coherence. Unlike the classical transitioning wakes, the pairing of the roller is bypassed. Instead, the spanwise-aligned bulges appear from the initially turbulent half-wake. Under the local shear of the Blasius boundary layer, these bulges undergo a “kinking-and-stretching” mechanism similar to that of the mixing layer. The spanwise organization of the structures is maintained far downstream.
The magnetic reversal characteristics of 32-bit composite element magnetic barcodes
Authors: Newton P. J. , De Los Santos Valladares L. , Celis Rojas R. , Barnes C. H. W.
Published: October 2019

Magnetic barcodes containing 32 composite element bits have been produced and measured in order to optimize the design of magnetic microcarriers. Focused magneto-optic Kerr effect measurements allow the determination of the change in magnetic hysteresis when the width of magnetic elements is varied between bits, and the electron beam lithography used in production is confirmed to be accurate to ∼6 nm using scanning electron microscopy. The sharp magnetic switching observed, an important prerequisite for a functioning device, is attributed to the expected dipolar interactions between magnetic elements and the use of magnetically soft Permalloy. A crossover between two magnetic reversal behaviors is discovered when the magnetic elements are ∼200 nm wide. From these measurements, 12 bits were selected on which data can be written with a low probability of error, with the prospect of the other 20 bits being employed for error correction. We have therefore developed a nonvolatile magnetic memory on which 4096 unique codes can be programmed.
Reversible reactions controlled by surface diffusion on a sphere
Authors: Grebenkov Denis S.
Published: October 2019

We study diffusion of particles on the surface of a sphere toward a partially reactive circular target with partly reversible binding kinetics. We solve the coupled diffusion-reaction equations and obtain the exact expressions for the time-dependent concentration of particles and the total diffusive flux. Explicit asymptotic formulas are derived in the small target limit. This study reveals the strong effects of reversible binding kinetics onto diffusion-mediated reactions that may be relevant for many biochemical reactions on cell membranes.
Measurement of the curvature and height of the potential barrier for a dynamic quantum dot
Authors: Johnson N. , Yamahata G. , Fujiwara A.
Published: October 2019

We report a method to characterize the potential barrier of a dynamic quantum dot by measuring the barrier height and determining the curvature. We show that the loading statistics and hence accuracy of electron transfer through the dynamic quantum dot depend significantly on these parameters, and hence our method provides a detailed characterization of device performance. This method takes a further step towards tunable barrier shapes, which would greatly increase the accuracy of single electron sources, allowing the single electron current to be useful for quantum sensing, quantum information, and metrology. We apply our method to the case of a tunable-barrier single-electron pump, an exemplary device that shows promise as a source of hot single electron wavepackets.
Cross-verification of neoclassical transport solutions from XGCa against NEO
Authors: Hager R. , Dominski J. , Chang C. S.
Published: October 2019

Radial neoclassical transport from the global gyrokinetic code XGC has been cross-verified against the local drift-kinetic neoclassical code NEO in NEO's local regime using a Grad-Shafranov equilibrium with a circular boundary. XGC shows excellent agreement with NEO, except for a difference of approximately 10% in the ion heat flux. Close investigation reveals that this difference is due to the simplification in NEO to use the same Coulomb logarithm ln Λ to represent all particle species, while XGC uses different formulas for collisions between different species [J. D. Huba, NRL Plasma Formulary (Naval Research Laboratory, Washington, DC, 2018)]. When XGC uses NEO's Coulomb logarithm, excellent agreement in the ion heat flux is recovered. The present work not only crossverifies the equation solvers in two codes, but also verifies that the gyrokinetic and the drift-kinetic equations agree and that the linearized and nonlinear Coulomb collision operators agree in the mild gradient, local regime.
New strategies for colloidal-quantum-dot-based intermediate-band solar cells
Authors: Califano Marco , Skibinsky-Gitlin Erik S. , Gómez-Campos Francisco M. , Rodríguez-Bolívar Salvador
Published: October 2019

The intermediate-band solar cell (IBSC) concept promises to increase the efficiency limit in a single-junction solar cell through the absorption of below-bandgap-energy photons. Despite their operating principle having been proposed over 20 years ago, IBSCs have not delivered on this promise yet, and the devices fabricated so far, mainly based on embedded epitaxial quantum dots, have instead operated with lower efficiency than conventional solar cells. A new paradigm, based on the exploitation as the intermediate band of the intragap states naturally occurring in the density functional theory description of colloidal (i.e., chemically synthesized) quantum dots, was suggested recently. Here, we revisit this intriguing concept unveiling its shortcomings and propose two alternative schemes: in the first, the localized electron surface trap states, ubiquitously found in commonly synthesized colloidal quantum dots, are used as intermediate bands in strongly coupled films made of small InAs nanocrystals and, in the second scheme, the intermediate band is provided by the conduction-band-minimum-derived miniband in films of larger InAs nanocrystals. Both schemes yield estimated limiting IBSC efficiencies exceeding Shockley-Queisser’s limit for a single absorber.
Laser refrigeration of gas filled hollow-core fibres
Authors: Sommer C. , Joly N. Y. , Ritsch H. , Genes C.
Published: October 2019

We evaluate prospects, performance and temperature limits of a new approach to macroscopic scale laser refrigeration. The considered refrigeration device is based on exciplex-mediated frequency up-conversion inside hollow-core fibers pressurized with a dopant - buffer gas mixture. Exciplexes are excited molecular states formed by two atoms (dopant and buffer) which do not form a molecule in the ground state but exhibit bound states for electronically excited states. The cooling cycle consists of absorption of laser photons during atomic collisions inducing light assisted exciplex formation followed by blue-shifted spontaneous emission on the atomic line of the bare dopant atoms after molecular separation. This process, closely related to reversing the gain mechanism in excimer lasers, allows for a large fraction of collision energy to be extracted in each cycle. The hollow-core fiber plays a crucial role as it allows for strong light-matter interactions over a long distance, which maximizes the cooling rate per unit volume and the cooling efficiency per injected photon while limiting re-absorption of spontaneously emitted photons channeled into unguided radiation modes. Using quantum optical rate equations and refined dynamical simulations we derive general conditions for efficient cooling of both the gas and subsequently of the surrounding solid state environment. Our analytical approach is applicable to any specific exciplex system considered and reveals the shape of the exciplex potential landscapes as well as the density of the dopant as crucial tuning knobs. The derived scaling laws allow for the identification of optimal exciplex characteristics that help to choose suitable gas mixtures that maximize the refrigeration efficiency for specific applications.
Ferroelectric properties of gradient doped Y2O3:HfO2 thin films grown by pulsed laser deposition
Authors: Shao Qianqian , Wang Xudong , Jiang Wei , Chen Yan , Zhang Xiaoyu , Tu Luqi , Lin Tie , Shen Hong , Meng Xiangjian , Liu Aiyun , Wang Jianlu
Published: October 2019

A HfO2-based thin film is a nanoscale ferroelectric material with a high-k dielectric and CMOS compatibility, which make it a promising candidate for high-performance electronics. Here, we demonstrate the synthesis of a ferroelectric Y-doped HfO2 (HYO) thin film by pulsed laser deposition. This HYO thin film is gradient doped by alternately depositing a HfO2 ceramic target and a Y2O3 ceramic target. In the films, the orthorhombic phase, ferroelectric phase, is proved by grazing incidence x-ray diffraction and scanning transmission electron microscopy measurements. Moreover, the HYO thin film embraces outstanding ferroelectric and dielectric properties, its remanent polarization is up to 10.5 μC/cm2, and the dielectric constant is 27. The 180° inversion of the domain can be observed in a piezoelectric power microscopy image, while the phase contrast of the write domain fades with time. Therefore, this work provides a reliable approach to obtain a ferroelectric HYO thin film, which enables great potential in future high-performance nanoelectronics.
Optical excitation density dependence of spin dynamics in bulk cubic GaN
Authors: Buß J. H. , Schupp T. , As D. J. , Hägele D. , Rudolph J.
Published: October 2019

The influence of the optical excitation density on the electron spin dynamics is experimentally investigated in bulk cubic GaN by time-resolved magneto-optical Kerr-rotation spectroscopy. The nanosecond spin relaxation times in moderately n-doped β-GaN decrease with increasing excitation density, though the effective lifetimes of the optically excited carriers are almost two orders of magnitude shorter than the spin relaxation times. This counterintuitive finding is explained by the heating of the electron system due to the excitation process. The spin relaxation times in degenerately n-doped β-GaN are found to be independent of excitation density as the very high electron Fermi temperature completely dominates over carrier heating processes in this case.
Bacterial self healing cement based materials: Mechanism at nanoscale
Authors: Lu Shunan , Chen Minghui , Dang Yudong , Cao Ling , He Jialuo , Zhong Jing
Published: October 2019

As the most challenging problem of concrete, cracking does not only reduce the mechanical properties, but also jeopardize the durability and service life of concrete. Currently, to enhance the lifespan of concrete, self-healing systems are embedded in the concrete and make the concrete be capable of healing the microcracks by itself. A self-healing system that employ bacteria to heal the microcracks is a promising approach. In the present study, the authors utilized the lightweight aggregates (LWAs) impregnated with the solution of Bacillus pseudofirmus B-4104 as a bacteria-based self-healing system. After the healing process, the obtained results indicated that the specific self-healing system could achieve 112% mechanical recovery of the splitting tensile strength, decrease 82% of the gas permeability and 87.4% of the water sorptivity. Thorough investigation by scanning electron microscopy (SEM) combined with Energy Dispersive X-Ray Spectroscopy (EDS) uncover that it is the crystalline healing products at nanoscale that fill the microcracks and eventually healing the samples. Moreover, the healing product showed good compatibility with the cement matrix and regular cubic crystallinity. Further investigations are necessary to establish a relationship between the crack width and the healing efficiency of this bacteria-based self-healing system.
Unified description of sound velocities in strongly coupled Yukawa systems of different spatial dimensionality
Authors: Khrapak Sergey A.
Published: October 2019

Sound velocities in classical single-component fluids with Yukawa (screened Coulomb) interactions are systematically evaluated and analyzed in one-, two-, and three spatial dimensions (D=1,2,3). In the strongly coupled regime, the convenient sound velocity scale is given by Q2/Δm, where Q is the particle charge, m is the particle mass, n is the particle density, and Δ=n−1/D is the unified interparticle distance. The sound velocity can be expressed as a product of this scaling factor and a dimension-dependent function of the screening parameter, κ=Δ/λ, where λ is the screening length. A unified approach is used to derive explicit expressions for these dimension-dependent functions in the weakly screened regime (κ≲3). It is also demonstrated that for stronger screening (κ≳3), the effect of spatial dimensionality virtually disappears, the longitudinal sound velocities approach a common asymptote, and a one-dimensional nearest-neighbor approximation provides a relatively good estimate for this asymptote. This result is not specific to the Yukawa potential, but equally applies to other classical systems with steep repulsive interactions. An emerging relation to a popular simple freezing indicator is briefly discussed. Overall, the results can be useful when Yukawa interactions are relevant, in particular, in the context of complex (dusty) plasmas and colloidal suspensions.
Tuning the electronic structures and transport coefficients of Janus PtSSe monolayer with biaxial strain
Authors: Guo San-Dong , Guo Xiao-Shu , Deng Ye
Published: October 2019

Due to their great potential in electronics, optoelectronics, and piezoelectronics, Janus transition metal dichalcogenide monolayers have attracted an increased interest in research, and the MoSSe monolayer of them with the sandwiched S-Mo-Se structure has been synthesized experimentally. Here, we systematically study the effect of strain on electronic structures and transport properties of the Janus PtSSe monolayer. A detrimental effect on the power factor of the PtSSe monolayer can be observed when the spin-orbital coupling is included. With a/a0 from 0.94 to 1.06, the energy bandgap shows a nonmonotonic behavior, which is due to the position change of conduction band minimum. The strength of conduction bands convergence can be enhanced by changing the relative position of conduction band extrema caused by compressive strain, which is in favor of the n-type ZTe. Calculated results show that compressive strain can also induce flat valence bands around the Γ point near the Fermi level, which can lead to a high Seebeck coefficient due to large effective masses, giving rise to better p-type ZTe values. The calculated elastic constants with a/a0 from 0.94 to 1.06 all satisfy the mechanical stability criteria, which proves that the PtSSe monolayer is mechanically stable in the considered strain range. Our works provide a new route to tune the electronic structures and transport coefficients of the Janus PtSSe monolayer by biaxial strain and can motivate related experimental studies.
Two-photon excited photoluminescence of single perovskite nanocrystals
Authors: Cao Zengle , Lv Bihu , Zhang Huichao , Lv Yan , Zhang Chunfeng , Zhou Yong , Wang Xiaoyong , Xiao Min
Published: October 2019

Lead-halide perovskite nanocrystals (NCs) have emerged as a novel type of semiconductor nanostructure, attracting great research interests in both fundamental science and practical applications. Here, we compare the optical properties of single CsPbI3 NCs under both one-photon and two-photon excitations, mainly including the photoluminescence (PL) blinking and PL decay dynamics. By means of the PL saturation effect caused by multi-exciton Auger recombination, we have also estimated a two-photon absorption cross section of ∼6.8 × 106 GM for single CsPbI3 NCs. The ability to realize efficient two-photon excitation of single perovskite NCs with strongly suppressed background fluorescence will help not only to promote their bio-imaging and biolabeling applications but also to reveal and manipulate their delicate electronic structures for potential usage in quantum information processing.
Emerging ferromagnetic phase in self-assembled mixed valence manganite nanowires
Authors: Malik Iftikhar Ahmed , Wang Xueyun , Ma Ji , Zhang Qinghua , Lu Jingdi , Zhou Hua , Malik Muhammad Abdullah , Ahmed Irfan , Gu Lin , Xiong Changmin , Nan Ce-Wen , Zhang Jinxing
Published: October 2019

Nanoscale magnetism in oxides with the lateral size down to 300 nm is critical for scientific investigation and advanced technological applications such as spintronics, but often complicated to fabricate. Specifically, the emergent magnetic phenomena induced by the size effect attract tremendous attention. In this situation, fabrication of self-assembled nanoarchitectures in complex oxides and strategically modulating their properties are urgently needed. Here, we report the emerging single ferromagnetic phase state in self-assembled nanowires on the thin film surface of mixed valence manganite La0.5Sr0.5MnO3, by using low temperature magnetic force microscopy. The ferromagnetic state can be reversely switched in the presence of an external magnetic field. This work paves the way for manipulating the phase coexistence state without an external field and provides insight into the size limitation for designing next generation electronic and spintronic devices in complex oxide systems.
Identification of separate isoenergetic routes for vibrational energy flow in p-fluorotoluene
Authors: Gardner Adrian M. , Whalley Laura E. , Kemp David J. , Tuttle William D. , Wright Timothy G.
Published: October 2019

A deceptively simple feature in the S1 ← S0 spectrum of p-fluorotoluene (pFT), 1013 cm−1 above the origin, is studied using both zero-electron-kinetic-energy (ZEKE) and two-dimensional laser-induced fluorescence (2D-LIF) spectroscopy. It is found to consist of a cornucopia of overlapped transitions to eigenstates that arise from numerous interacting levels. A significant variation in the activity is seen employing both the ZEKE and 2D-LIF techniques. Detailed insight into the complicated spectra can be achieved, owing to the large number of vibrational wavenumbers that have been previously determined for the S0, S1, and D0+ states, summarized herein. It is found that the activity is dominated by two overtones, which are individually interacting with other levels, so providing largely independent routes for vibrational energy flow at the same internal energy. Additionally, other weak features located 900–1050 cm−1 above the origin are examined.
A generalized theorem on curvilinear three-web boundaries and its applications
Authors: Shelekhov A. M.
Published: October 2019

Suppose that a curvilinear three-web is given by the equation

. A specific structure of the derivatives of the function

is established that characterizes regular three-webs. This makes it possible to list all regular three-webs formed by the Cartesian net and a family of circles, and also by the Cartesian net and a family of second-order curves.

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