bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective amidation by a photocatalyzed umpolung reaction
Authors: Ghosh Debasish , Nandi Rajesh , Khamarui Saikat , Ghosh Sukla , Maiti Dilip K.
Published: March 2019

Herein, a metal-catalyzed organic transformation merged with another organophotocatalyst has been developed under mild conditions for the production of α-ketoamides.
Second generation DNA-encoded dynamic combinatorial chemical libraries
Authors: Reddavide Francesco V. , Cui Meiying , Lin Weilin , Fu Naiqiang , Heiden Stephan , Andrade Helena , Thompson Michael , Zhang Yixin
Published: March 2019

A novel DNA-encoded chemical library architecture can mimic the mechanisms of immunity to evolve binders through recombination, dynamics and adaption.
Revisiting Ag–π interactions with bis((pyrrol-2-yl)methylene)hydrazine: CC versus CN bond complexation
Authors: Baudron Stéphane A. , Chevreau Hubert
Published: March 2019

Crystallographic and theoretical investigations of the assembly of bis((pyrrol-2-yl)methylene)hydrazine with Ag(i) salts suggest that, in the solid state, Ag–π interactions involve CC rather than CN pyrrolic bonds, in contrast with an earlier and unique report with this ligand.
Correction: Competitor analysis of functional group H-bond donor and acceptor properties using the Cambridge Structural Database
Authors: McKenzie James , Lewis Richard P. I. , Hunter Christopher A.
Published: March 2019

Correction for ‘Competitor analysis of functional group H-bond donor and acceptor properties using the Cambridge Structural Database’ by James McKenzie et al., Phys. Chem. Chem. Phys., 2018, 20, 25324–25334.
Long-term hydrolytically stable bond formation for future membrane-based deep ocean microfluidic chemical sensors
Authors: Tweedie M. , Sun D. , Ward B. , Maguire P. D.
Published: March 2019

Future ocean profiling of dissolved inorganic carbon and other analytes will require miniaturised chemical analysis systems based on sealed gas membranes between two fluid channels.
Tetradic phosphor white light with variable CCT and superlative CRI through organolead halide perovskite nanocrystals
Authors: Adhikari Gopi C. , Vargas Preston A. , Zhu Hongyang , Grigoriev Alexei , Zhu Peifen
Published: March 2019

Exceptional CRI and variable CCT via fourfold phosphors to create a high-quality broadband white-emission with a controllable hue.
MOF nanoleaves as new sacrificial templates for the fabrication of nanoporous Co–Nx/C electrocatalysts for oxygen reduction
Authors: Li Jingjing , Xia Wei , Tang Jing , Tan Haibo , Wang Jiayu , Kaneti Yusuf Valentino , Bando Yoshio , Wang Tao , He Jianping , Yamauchi Yusuke
Published: March 2019

This work reports two-dimensional nanoporous Co–Nx/C electrocatalysts with high performance for oxygen reduction reaction and zinc–air battery.
Doxorubicin release by magnetic inductive heating and in vivo hyperthermia-chemotherapy combined cancer treatment of multifunctional magnetic nanoparticles
Authors: Ha Phuong Thu , Le Thi Thu Huong , Bui Thuc Quang , Pham Hong Nam , Ho Anh Son , Nguyen Linh Toan
Published: March 2019

Multifunctional nanosystems help to control drug release and highly improve the cancer treatment efficacy in in vivo models.
Distinct photophysical properties in atom-precise silver and copper nanocluster analogues
Authors: Li Yan-Ling , Wang Zhao-Yang , Ma Xiao-Hong , Luo Peng , Du Chen-Xia , Zang Shuang-Quan
Published: March 2019

A pair of atom-precise luminescent copper/silver-thiolate cluster analogues, Cu17 and Ag17 were assembled by bottom-up synthesis and cluster-to-cluster conversion. Metal-atom exchange induced the redshift of the optical absorption and blueshift of emission of Ag17 in the solid-state compared to that of Cu17.
6-Polyamino-substituted quinolines: synthesis and multiple metal (CuII, HgIIand ZnII) monitoring in aqueous media
Authors: Abel Anton S. , Averin Alexei D. , Cheprakov Andrey V. , Roznyatovsky Vitaly A. , Denat Franck , Bessmertnykh-Lemeune Alla , Beletskaya Irina P.
Published: March 2019

Multi-signaling or multi-metal optical analysis of toxic metal ions under physiological conditions.
Donor–acceptor polymers containing thiazole-fused benzothiadiazole acceptor units for organic solar cells
Authors: Nakamura Tomoya , Ishikura Yasuhisa , Arakawa Noriko , Hori Megumi , Satou Motoi , Endo Masaru , Masui Hisashi , Fuse Shinichiro , Takahashi Takashi , Murata Yasujiro , Murdey Richard , Wakamiya Atsushi
Published: March 2019

Two p-type semiconducting donor–acceptor polymers were designed and synthesized for use in organic solar cells.
Sensitive and fast fluorescence-based indirect sensing of TATP
Authors: Fan Shengqiang , Burn Paul L. , Shaw Paul E.
Published: March 2019

We report fast and sensitive fluorescence “turn-on” sensing of TATP via hydrogen peroxide detection using fluorinated fluorenylboronate ester derivatives.
Ultra-fast shock-wave combustion synthesis of nanostructured silicon from sand with excellent Li storage performance
Authors: Kamali Ali Reza , Haghighat-Shishavan Safa , Nazarian-Samani Masoud , Rezaei Asma , Kim Kwang-Bum
Published: March 2019

A novel shock-wave combustion synthesis method was developed for ultra-scalable, clean and energy efficient conversion of sand to nanostructured silicon with excellent performance as an anode material for Li-ion batteries.
Recent advances in precious metal-free bifunctional catalysts for electrochemical conversion systems
Authors: Xu Huimin , Ci Suqin , Ding Yichun , Wang Genxiang , Wen Zhenhai
Published: March 2019

The gradually “depleting” fossil fuels calls for development sustainable and pollution free energy, this work summarize the recent progress in exploring bifunctional electrocatalysts toward several potential electrochemical conversion devices.
Correction: Exfoliation of amorphous phthalocyanine conjugated polymers into ultrathin nanosheets for highly efficient oxygen reduction
Authors: Liu Wenping , Wang Chiming , Zhang Lijie , Pan Houhe , Liu Wenbo , Chen Jun , Yang Dongjiang , Xiang Yanjuan , Wang Kang , Jiang Jianzhuang , Yao Xiangdong
Published: March 2019

Correction for ‘Exfoliation of amorphous phthalocyanine conjugated polymers into ultrathin nanosheets for highly efficient oxygen reduction’ by Wenping Liu et al., J. Mater. Chem. A, 2019, 7, 3112–3119.
A cyclopentadithiophene-bridged small molecule acceptor with near-infrared light absorption for efficient organic solar cells
Authors: Yi Yuan-Qiu-Qiang , Feng Huanran , Ke Xin , Yan Jing , Chang Meijia , Wan Xiangjian , Li Chenxi , Chen Yongsheng
Published: March 2019

A cyclopentadithiophene (DTC)-bridged acceptor–donor–acceptor (A–D–A) backboned small molecule acceptor (SMA), namely IDTC-4Cl, was designed and synthesized.
Polar coded distribution matching
Authors: İşcan O. , Böhnke R. , Xu W.
Published: March 2019

A fixed‐length to fixed‐length binary distribution matcher based on polar coding is presented that can generate an output sequence with a target probability distribution in a reversible way. An algorithm to obtain the required parameters and their proper approximations are provided. The method is further extended to support arbitrary output lengths and transmission over noisy channels.
Linear‐cavity mode‐locked fibre laser with cylindrical vector beam generation
Authors: Xu Yang , Cai Yu , Wan Hongdan , Zhang Zuxing
Published: March 2019

A cylindrical vector beam (CVB)‐pulsed fibre laser with compact linear‐cavity configuration has been demonstrated, using a two‐mode fibre (TMF) Bragg grating (TM‐FBG) for mode discrimination and a semiconductor saturable absorber mirror (SESAM) for passive mode‐locking. As a result, mode‐locked CVB pulses with fundamental repetition rate of 10.295 MHz have been obtained. Besides, with increased pump power harmonic, mode‐locked CVB pulses have been achieved, for the first time.
Modified instantaneous symmetrical component algorithm‐based control for operating electric spring in active power filter mode
Authors: Pawar Rutuja S. , Gawande Snehal Panjabrao , Nagpure Ravikiran N. , Waghmare Manoj Arun
Published: March 2019

Recently, a new technology called as electric spring (ES) is used for suppressing the voltage fluctuation and stabilising the smart grid. To address the harmonic issue in case of non‐linear critical load and for achieving voltage regulation in presence of disturbance source, this paper suggests ES‐1 topology and proposes modified instantaneous symmetrical component algorithm (ISCA). The reference currents extracted using proposed ISCA with hysteresis current control (HCC) operates ES in active power filter (APF) mode. This improved algorithm can mitigate the harmonics in the source currents effectively, facilitate to set the source‐side power factor (PF) to the desired value (unity) and simultaneously perform the task of critical load voltage regulation using single multifunctional control. A detailed comparison between existing ES control schemes and the proposed ISCA approach highlights the benefits of proposed control in terms of its multifunctional capabilities. The ES‐1 utilises three‐phase inverter with DC‐link capacitor that compensates unbalance non‐critical load and non‐linear critical load. To demonstrate the effectiveness of proposed method to operate ES in APF mode, the results using MATLAB simulations are presented and compared with those few obtained for similar existing control schemes. The proposed control is also validated using experimental studies.
Business ist Business – Kolumne
Authors: Schiewack Michael
Published: March 2019

Kennen Sie das? Im Vorfeld ist laut Klienten alles klar und kein Problem. Die Therapie läuft gut, aber am Ende will die private Krankenversicherung nicht zahlen. So erging es zumindest Michael Schiewack. Doch er hat seinen Preis – da hilft auch kein Augenzwinkern.
Ergotherapie am Puls der Zeit – 13. ergotag 2019
Authors: Mischner Julia
Published: March 2019

Am 27. Januar 2019 fand der 13. ergotag auf der Messe Stuttgart statt. 260 Interessierte nahmen zum diesjährigen Motto „Betätigung – ein Upgrade für die Ergotherapie“ teil. Neun Referentinnen aus fünf Ländern füllten die „Betätigung“ mit Leben.
Structure-Activity Relationship of Transfection-Modulating Saponins – A Pursuit for the Optimal Gene Trafficker
Authors: Sama Simko , Jerz Gerold , Thakur Mayank , Melzig Matthias , Weng Alexander
Published: March 2019

The ability of certain triterpenoid saponins to modulate the endosomal release during the process of endocytosis and to ensure a nontoxic and efficient transfection recently led to an exceptional interest in the field of nonviral gene delivery. In vitro and in vivo studies demonstrated promising results in terms of tumor growth inhibition after the delivery of a suicide gene such as saporin and dianthin. With that, the question arises which structural features are necessary or advantageous to achieve an effective endosomal escape. Former studies described certain important characteristics a potent saponin should have. Particularly SA1641 (Gypsophila paniculata) and SO1861 (Saponaria officinalis) played an utmost important role to get a first insight into the structure-activity relationship. However, a number of issues such as the purpose of functional groups on the aglycon and the substitution of sugars and their modification remain unsolved and their value needs to be specified. By conducting a screening of several diverse saponins in terms of their transfection improving ability, we aimed to examine these questions in more detail and get a better understanding of the relevant features. The transfection of Neuro-2A-cells with GFP-DNA containing peptide-based nanoplexes provided a reliable method in order to compare the activity of the saponins. With that, we were able to provide new and essential insights regarding the structure-activity relationship of transfection-modulating saponins and give an idea of how a highly potent saponin for future gene therapies may look like.
Anatomical Study of the Facial Recess with Implications in Round Window Visibility for Cochlear Implantation: Personal Observations and Review of the Literature
Authors: Jain Shraddha , Deshmukh PT , Lakhotia Pooja , Kalambe Sanika , Chandravanshi Deepshikha , Khatri Mohnish
Published: March 2019

Introduction Posterior tympanotomy through facial recess (FR) is the conventional and most preferred approach to facilitate cochlear implantation, especially when the electrode is inserted through the round window. The complications of the FR approach can be minimized by proper understanding of the anatomy of the FR.

Objective The present study was undertaken to assess the various parameters of FR and round window visibility, which may be of relevance for cochlear implant surgery.

Methods Thirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of FR and posterior tympanum. Photographs were taken with an 18 megapixels digital camera, which were then imported to a computer to determine various parameters.

Results The mean distance from the take-off point/crotch of the chorda tympani nerve (CTN) to the stylomastoid foramen was 4.08 ± 0.8 mm (range of 2.06 - 5.5 mm). The variations in the course of the CTN included origin at the level of the lateral semicircular canal. The mean chorda-facial angle in our study was 26.91° ± 1.19°, with a range of 25° to 28.69°. The mean FR length ranged between 9.4 mm and 18.56 mm (mean of 12.41 ± 2.91mm) and varied with the origin of the CTN and pneumatization of temporal bone. The average maximum width of the FR was 2.93 ± 0.4 mm (range 2.24–3.45 mm) and the mean width of the FR at the level of the round window was 2.65 ± 0.41 mm.

Conclusion The FR approach provides good access to the round window membrane in all cases. In some cases, table adjustment is required.
Super-resolution Diffusion Tensor Imaging for Delineating the Facial Nerve in Patients with Vestibular Schwannoma
Authors: Epprecht Lorenz , Kozin Elliott D. , Piccirelli Marco , Kanumuri Vivek V. , Tarabichi Osama , Remenschneider Aaron , Barker Frederick G. , McKenna Michael J. , Huber Alexander M. , Cunnane Marybeth E. , Reinshagen Katherine L. , Lee Daniel J.
Published: March 2019

Objectives Predicting the course of cranial nerves (CNs) VII and VIII in the cerebellopontine angle on preoperative imaging for vestibular schwannoma (VS) may help guide surgical resection and reduce complications. Diffusion magnetic resonance imaging dMRI is commonly used for this purpose, but is limited by its resolution. We investigate the use of super-resolution reconstruction (SRR), where several different dMRIs are combined into one dataset. We hypothesize that SRR improves the visualization of the CN VII and VIII.

Design Retrospective case review.

Setting Tertiary referral center. SRR was performed on the basis of axial and parasagittal single-shot epiplanar diffusion tensor imaging on a 3.0-tesla MRI scanner.

Participants Seventeen adult patients with suspected neoplasms of the lateral skull base.

Main Outcome Measures We assessed separability of the two distinct nerves on fractional anisotropy (FA) maps, the tractography of the nerves through the cerebrospinal fluid (CSF), and FA in the CSF as a measure of noise.

Results SRR increases separability of the CN VII and VIII (16/17 vs. 0/17, p = 0.008). Mean FA of CSF surrounding the nerves is significantly lower in SRRs (0.07 ± 0.02 vs. 0.13 ± 0.03 [axial images]/0.14 ± 0.05 [parasagittal images], p = 0.00003/p = 0.00005). Combined scanning times (parasagittal and axial) used for SRR were shorter (8 minute 25 seconds) than a comparable high-resolution scan (15 minute 17 seconds).

Conclusion SRR improves the resolution of CN VII and VIII. The technique can be readily applied in the clinical setting, improving surgical counseling and planning in patients with VS.
En bloc Resection of Solitary Cranial Tumors: An Algorithmic Reconstructive Approach
Authors: Egeler Sabine , Johnson Anna , Wu Winona , Bucknor Alexandra , Chen Yen-Chou , Bayoumi Ahmed , Kasper Ekkehard
Published: March 2019

Background This study analyzes the surgical outcomes for single setting surgeries involving en-bloc solitary calvarial tumor resection in combination with three-layered reconstruction, presenting a novel planning algorithm.

Methods Data were retrieved for all patients undergoing single-stage tumor excision, using our novel three-layered reconstructive approach (duraplasty, cranioplasty, and soft tissue reconstruction) between 2005 and 2017 at a single tertiary hospital center. Patients ≥18 years with a Karnofsky Performance score (KPS) >70 and a life expectancy of > 2 months were included. Patient characteristics, surgical specifics, histological diagnoses, outcomes, and complications were reviewed.

Results Eighteen single-staged excisions and three-layered reconstructions were performed. Seven patients presented with primary tumors and 11 patients with metastases. Mean age was 62 years. Mean follow-up time was 39 months. Primary closure was used in 12 of 18 patients, microvascular free flap with skin grafting in 4 of 18, and local advancement or rotational flap in 2 of 18. Two compromised free flaps were revised. There was no flap necrosis, skin graft failure, or wound infection observed in this series. Neurosurgical complications included two cases with seizures, one sublesional intraparenchymal hematoma, one adjacent parenchymal infarct, one case of delayed postradiation cerebrospinal fluid leakage, and one case of subdural hemorrhage.

Conclusion En-bloc excision followed by three-layered reconstruction is a feasible and often suitable single-stage technique for complex solitary metastasis or primary calvarial tumors, which historically have been challenging to treat. It can offer an alternative approach to primary and metastatic calvarial tumors other than palliative treatment or hospice care.
Rationale and Results for Fixed-Bearing Pivoting Designs in Total Knee Arthroplasty
Authors: Banks Scott A. , Deckard Evan , Hodge W. Andrew , Meneghini R. Michael
Published: March 2019

Total knee arthroplasty (TKA) is a maturing technology, and the focus for improvement centers on optimizing patient satisfaction and further reducing revisions. It is commonly assumed that achieving closer-to-normal knee mechanics in a TKA will result in further improvement in outcomes and revision rates. Fixed-bearing TKA designs with asymmetric pivoting articulations are designed to provide more natural joint stability and kinematics. These designs have been used for more than 20 years and there is a substantial body of literature characterizing their performance. This article reviews the various design types of fixed-bearing pivoting TKA designs, and recounts their clinical, functional, and patient-preference performance from peer-reviewed studies. To date, the evidence suggests there is measurable benefit to providing closer-to-normal joint stability and kinematics, and that fixed-bearing, pivoting TKA designs may decrease instability-related revisions and improve patient satisfaction.
Benign Pediatric Tumors and Tumor-Like Conditions of the Hip
Authors: Miller Justin , Patel Jay , Gianakos Arianna , Hoskins Tyler , Goyette David , Wittig James
Published: March 2019

Hip pain in the pediatric population can be a challenging presenting complaint to assess. An extensive differential list, including the possibility of infection, transient conditions, and malignancy, results in numerous questions that can render diagnosis difficult. As clinicians, it is imperative that we have the ability to recognize, properly diagnose, and possibly treat the multitude of potential pediatric hip disorders. Here the authors present the incidence, characteristics, and treatment of various benign tumors and tumor-like conditions of the pediatric hip.
Phase-sensitive dynamic susceptibility setup for measurements in pulsed magnetic fields
Authors: Postulka Lars , Eibisch Paul , Holzmann Andreas , Wolf Bernd , Lang Michael
Published: March 2019

Dynamic susceptibility, commonly referred to as AC susceptibility, χAC, is a powerful tool to characterize a material’s magnetic properties in the presence of a magnetic field B, such as magnetic ordering or spin-relaxation phenomena. The standard technique for accessing χAC is based on measurements of the voltage which is induced in a coil by changes of a sample’s magnetization in response to a small oscillating magnetic field. Importantly, this setup allows for a phase-sensitive detection of the susceptibility, thereby providing information on the magnetization dynamics. This method is frequently used in the low-field range, up to several Tesla, where DC fields are readily available. However, there is a growing demand for such magnetic measurements at higher fields, conveniently accessible by the use of pulse-field technology. Whereas various techniques are available for measuring the in-phase part of the susceptibility χAC′, none of them allows for the determination of the out-of-phase part χAC″. Here we present a realization of an AC susceptometer for measurements of both the in- and out-of-phase component at frequencies up to 47 kHz and an oscillating amplitude of 1.5 mT in a pulsed magnetic field. With this setup, a magnetic signal of 3.6 × 10−6 emu can be resolved. As the setup also enables susceptibility measurements to be performed before and after the field pulse, it can be used to detect temperature changes in response to changes of the magnetic field. This will be demonstrated by measurements on the low-dimensional spin-1/2 system CuSO4·5H2O.
Mixed mode oscillations and phase locking in coupled FitzHugh-Nagumo model neurons
Authors: Davison Elizabeth N. , Aminzare Zahra , Dey Biswadip , Ehrich Leonard Naomi
Published: March 2019

We study the dynamics of a low-dimensional system of coupled model neurons as a step towards understanding the vastly complex network of neurons in the brain. We analyze the bifurcation structure of a system of two model neurons with unidirectional coupling as a function of two physiologically relevant parameters: the external current input only to the first neuron and the strength of the coupling from the first to the second neuron. Leveraging a timescale separation, we prove necessary conditions for multiple timescale phenomena observed in the coupled system, including canard solutions and mixed mode oscillations. For a larger network of model neurons, we present a sufficient condition for phase locking when external inputs are heterogeneous. Finally, we generalize our results to directed trees of model neurons with heterogeneous inputs.
Using reflection and transmission coefficients to retrieve surface parameters for an anisotropic metascreen: With a discussion on conversion between TE and TM polarizations
Authors: Holloway Christopher L. , Kuester Edward F. , Haddab Abdulaziz H.
Published: March 2019

In recent work, we derived generalized sheet transition conditions (GSTCs) for electromagnetic fields at the surface of a metascreen (a metasurface with a “fishnet” structure, i.e., a periodic array of arbitrary spaced apertures in a relatively impenetrable surface). The effective electric and magnetic surface susceptibilities and surface porosities that appear explicitly in the GSTCs are uniquely defined and as such serve as the physical quantities that most appropriately characterize the metascreen. These surface parameters are related to the geometry of the apertures that constitute the metascreen and can exhibit anisotropic properties if this geometry is sufficiently asymmetric. These anisotropic properties can result in mode conversion between transverse electric (TE) and transverse magnetic (TM) polarizations when a plane-wave is incident onto a metascreen. Here, we use these GSTCs to derive the plane-wave reflection (R) and transmission (T) coefficients of an anisotropic metascreen, in which the coupling between TE and TM polarizations is illustrated. These expressions for R and T are used to develop a retrieval approach for determining the uniquely defined effective surface susceptibilities and surface porosities that characterize the metascreen from measured or simulated data. We present an example of a metascreen whose apertures are filled with a high-contrast dielectric, which shows interesting resonances at frequencies where no resonances exist when the apertures are not filled.
An analytical plasma screening potential based on the self-consistent-field ion-sphere model
Authors: Li X. , Rosmej F. B. , Lisitsa V. S. , Astapenko V. A.
Published: March 2019

The radial dependence of the free electron density within the ion sphere radius in finite temperature dense plasmas shows characteristic scaling laws that permit us to derive analytical plasma screening potentials. A generalized analytical approach is developed which shows good agreement with self-consistent quantum mechanical calculations. It is empirically discovered that anomalous strong scaling in the analytical model provides agreement with data obtained in a regime where the lattice structure still prevails.
Accurate non-invasive measurement of the turn-on transition of fast gated single photon avalanche diodes
Authors: Cominelli A. , Acconcia G. , Labanca I. , Ghioni M. , Rech I.
Published: March 2019

Recently developed Active Quenching Circuits (AQCs) with fast-gating capabilities allow us to control a single photon avalanche diode with gate windows in the nanosecond and sub-nanosecond range, thus paving the way to advanced applications, especially in the field of time-correlated single photon counting. In this scenario, an accurate measurement of the time needed by the AQC to turn-on the detector is of utmost importance. Indeed, it permits us to evaluate the impact of the system in specific applications and provides a tool to designers to understand AQC limitations and to enhance its performance. Here we propose a simple non-invasive technique to accurately measure the time needed by a gated system to turn on the detector. The effectiveness of the measure has been proved on a gated system, and results have been compared to those obtained starting from the distribution of recorded photons under constant illumination, which is a widely used approach in the literature. The great advantage of the proposed approach is that it avoids typical artifacts that affect other kinds of measurements.
Fluttering and divergence instability of functionally graded viscoelastic nanotubes conveying fluid based on nonlocal strain gradient theory
Authors: Nematollahi Mohammad Sadegh , Mohammadi Hossein , Taghvaei Sajjad
Published: March 2019

In this paper, a size-dependent viscoelastic pipe model is developed to investigate the size effects on flutter and divergence instability of functionally graded viscoelastic nanotubes conveying fluid. The nonlocal strain gradient theory and the Kelvin-Voigt model are used to consider the significance of nonlocal field, strain gradient field, and viscoelastic damping effects. The dimensionless equation of transverse motion and related classical and non-classical boundary conditions are derived using the variational approach. The partial differential equations are discretized to a system of ordinary differential equations by the use of Galerkin’s method. The frequency equation is obtained as a function of dimensionless flow velocity, small-scale parameters, damping coefficient, and power-law parameter. Numerical results are presented to study the dynamical behavior of the system and are compared with experimental and theoretical results reported by other researchers. Coupled and single mode fluttering related to higher vibration modes of fluid-conveying nanotubes supported at both ends are studied for the first time. It is found that coupled mode fluttering can be seen for different vibration modes by increasing the flow velocity in the absence of structural damping. Structural damping changes the dynamical behavior of the system, in which by increasing the flow velocity, single mode fluttering occurs instead of coupled mode fluttering. In addition, the presence of structural damping increases the critical flow velocity and, as a result, increases the stability of the system. The results also show that increasing the nonlocal parameter will have a stiffness-softening effect, while increasing the strain gradient length scale has an opposing effect.
Modulational instability and ion-acoustic envelopes in dense plasmas with trapped/untrapped electrons
Authors: Irfan M. , Ali S. , Mirza Arshad M.
Published: March 2019

The linear and nonlinear properties of ion-acoustic rogons and associated modulational instability (MI) are studied in an unmagnetized dense electron-ion plasma, containing degenerate trapped/untrapped electrons and classical adiabatic ions. Solving the quantum hydrodynamic equations by using the standard multiscale reductive perturbation technique, a nonlinear Schrödinger equation is derived, which admits potential envelopes to be stable (unstable) against the perturbations for PQ < 0 (PQ>0). Here, P and Q are the dispersion and nonlinearity coefficients, respectively. It is numerically shown that for the vanishing ionic temperature ratio (σ=0), the parametric regime at perturbation wavelengths λ≥2.5λeff (λ≤2.5λeff) is always modulationally stable (unstable); here, λeff is the effective screening length. Moreover, the finite ionic temperature (Ti≤10 eV) restores the modulational stability at relatively short wavelengths by confining MI within the perturbation range 4.5λeff≤λ≤1.3λeff. The parameter Θ(=Te/22μ) shows the impact of the untrapped electrons which not only enhances (reduces) the angular frequency (group speed) of the envelope but also piles up the wave crests (energy) to produce the MI. Furthermore, due to degenerate trapped electrons, the instability domain gets widened in the limit PQ > 0 and leads to the onset of MI and unstable excitations. The study has important results for understanding the mechanism of MI and unstable modes in the context of astrophysical environments (white dwarfs, neutron stars, etc.,) and high density experiments.
“Cognitive” modes in small networks of almost identical chemical oscillators with pulsatile inhibitory coupling
Authors: Vanag Vladimir K.
Published: March 2019

The Lavrova-Vanag (LV) model of the periodical Belousov-Zhabotinsky (BZ) reaction has been investigated at pulsed self-perturbations, when a sharp spike of the BZ reaction induces a short inhibitory pulse that perturbs the BZ reaction after some time τ since each spike. The dynamics of this BZ system is strongly dependent on the amplitude Cinh of the perturbing pulses. At Cinh > Ccr, a new pseudo-steady state (SS) emerges far away from the limit cycle of the unperturbed BZ oscillator. The perturbed BZ system spends rather long time in the vicinity of this pseudo-SS, which serves as a trap for phase trajectories. As a result, the dynamics of the BZ system changes qualitatively. We observe new modes with packed spikes separated by either long “silent” dynamics or small-amplitude oscillations around pseudo-SS, depending on Cinh. Networks of two or three LV-BZ oscillators with strong pulsatile coupling and self-inhibition are able to generate so-called “cognitive” modes, which are very sensitive to small changes in Cinh. We demonstrate how the coupling between the BZ oscillators in these networks should be organized to find “cognitive” modes.
Electron trapping in freely expanding ultracold neutral plasmas
Authors: Ayllon R. , Terças H. , Mendonça J. T.
Published: March 2019

We report on the self-induced electron trapping occurring in an ultracold neutral plasma that is set to expand freely. At the early stages of the plasma, the ions are not thermalized which follow a Gaussian spatial profile, providing the trapping to the coldest electrons. In the present work, we provide a theoretical model describing the electrostatic potential and perform molecular dynamics simulations to validate our findings. We show that in the strong confinement regime, the plasma potential is of a Thomas-Fermi type, similar to the case of heavy atomic species. The numerically simulated spatial profiles of the particles corroborate this claim. We also extract the electron temperature and coupling parameter from the simulation, so the duration of the transient Thomas-Fermi is obtained.
A normal form method for the determination of oscillations characteristics near the primary Hopf bifurcation in bandpass optoelectronic oscillators: Theory and experiment
Authors: Talla Mbé Jimmi H. , Woafo Paul , Chembo Yanne K.
Published: March 2019

We propose a framework for the analysis of the integro-differential delay Ikeda equations ruling the dynamics of bandpass optoelectronic oscillators (OEOs). Our framework is based on the normal form reduction of OEOs and helps in the determination of the amplitude and the frequency of the primary Hopf limit-cycles as a function of the time delay and other parameters. The study is carried for both the negative and the positive slopes of the sinusoidal transfer function, and our analytical results are confirmed by the numerical and experimental data.
Demonstration of tomographic imaging of isotope distribution by nuclear resonance fluorescence
Authors: Zen Heishun , Ohgaki Hideaki , Taira Yoshitaka , Hayakawa Takehito , Shizuma Toshiyuki , Daito Izuru , Yamazaki Jun-ichiro , Kii Toshiteru , Toyokawa Hiroyuki , Katoh Masahiro
Published: March 2019

Computed Tomography (CT) using X-ray attenuation by atomic effects is now widely used for medical diagnosis and industrial non-destructive inspection. In this study, we performed a tomographic imaging of isotope (208Pb) distribution by the Nuclear Resonance Fluorescence (NRF), i.e. isotope specific resonant absorption and scattering of gamma rays, using Laser Compton Scattering (LCS) gamma rays. The NRF-CT image which includes both effects of atomic attenuation and nuclear resonant attenuation was obtained. By accounting for the atomic attenuation measured by a conventional method at the same time, a clear 208Pb isotope CT image was obtained. The contrast degradation due to notch refilling caused by small-angle Compton scattering is discussed. This study clearly demonstrates the capability of the isotope-specific CT imaging based on nuclear resonant attenuation which will be a realistic technique when the next generation of extremely intense LCS gamma-ray sources will be available. The expected image acquisition time using these intense LCS gamma rays was discussed.
Critical behavior of power transmission network complex dynamics in the OPA model
Authors: Carreras Benjamin A. , Reynolds-Barredo José M. , Dobson Ian , Newman David E.
Published: March 2019

Many complex infrastructure systems, such as electric power transmission grids, display characteristics of a critical or near critical behavior with a risk of large cascading failures. Understanding this risk and its relation to the system state as it evolves could allow for a more realistic risk assessment and even for mitigation measures. We use the OPA model of cascading blackouts and grid evolution to describe and quantify regimes of criticality of the power grid.
Effect of aging on the current transport properties at gold/niobium-doped strontium titanate Schottky junctions
Authors: Hirose Sakyo , Ueda Shigenori , Ohashi Naoki
Published: March 2019

In this study, the effect of aging on current transport properties and the interface band structure of the Au/Nb-doped SrTiO3 (NSTO) junction was investigated. The as-fabricated Au/NSTO junctions showed extremely small rectification and exhibited rectifying current conduction and colossal electroresistance (CER) effect after exposure to air. In contrast, the Au/NSTO junctions kept in vacuum did not exhibit such aging behavior. Interestingly, the Au/NSTO junction capped with a Pt overlayer showed small rectification even after air exposure for one week. The changes in the potential profile with increasing air exposure time were assessed by X-ray photoemission techniques. The aforementioned time-dependent behaviors originated because of oxygen diffusion through the Au electrode, and it was found that oxygen stoichiometry at the electrode interface played an important role in the CER phenomena at the metal/NSTO junctions.
Magnetic field and orientation dependence of solid-state CIDNP
Authors: Sosnovsky Denis V. , Lukzen Nikita N. , Vieth Hans-Martin , Jeschke Gunnar , Gräsing Daniel , Bielytskyi Pavlo , Matysik Jörg , Ivanov Konstantin L.
Published: March 2019

The magnetic field dependence of Chemically Induced Dynamic Nuclear Polarization (CIDNP) in solid-state systems is analyzed theoretically with the aim to explain the puzzling sign change of polarization found at low fields [D. Gräsing et al., Sci. Rep. 7, 12111 (2017)]. We exploit the analysis of polarization in terms of level crossings and level anti-crossings trying to identify the positions of features in the CIDNP field dependence with specific crossings between spin energy levels of the radical pair. Theoretical treatment of solid-state CIDNP reveals a strong orientation dependence of polarization due to the spin dynamics conditioned by anisotropic spin interactions. Specifically, different anisotropic CIDNP mechanisms become active at different magnetic fields and different molecular orientations. Consequently, the field dependence and orientation dependence of polarization need to be analyzed together in order to rationalize experimental observations. By considering both magnetic field and orientation dependence of CIDNP, we are able to explain the previously measured CIDNP field dependence in photosynthetic reaction centers and to obtain a good qualitative agreement between the experimental observations and theoretical results.
Experimental setup to measure thermal waves generated by X-ray absorption using pyroelectric sensor
Authors: Kane S. R. , Sinha A. K. , Singh A. K. , Kumar Shailendra
Published: March 2019

Pyroelectric detectors are widely used for infrared radiation detection, whereas these can also be used in the X-ray region. They have multiple advantages when used at synchrotron radiation sources, such as (a) can be used with a white beam (high flux), (b) have a flat spectral response, and (c) can be used both as a detector and as a sample. However, when used in the hard X-ray region, absorption in the detector plays an important role depending upon the thickness of the detector. Hence, the estimation of the responsivity of the detector is important. In this paper, we report an improved experimental setup for the measurement of a pyroelectric signal in the hard X-ray region. The responsivity (V/W) of a pyroelectric detector for absorbed radiation in the hard x-ray region is measured. Measurements of the K-edge x-ray absorption fine structure of 10-μm copper and nickel foils are carried out using a LiTaO3 pyroelectric detector and compared with the measurements carried out using an ionization chamber as a sensor for the same foils. Absorption spectra near the Ta LIII and LII edges in LiTaO3, measured using a LiTaO3 crystal both as a sample and as a sensor, are also reported in this paper.
Role of intrinsic defects on the persistent luminescence of pristine and Mn doped ZnGa2O4
Authors: Wang Yun-Peng , Zhang Hai-Shan , Lin Li-Ting , Zhou Shi-Feng , Yao Yao , Yang Xiao-Bao , Zhao Yu-Jun
Published: March 2019

ZnGa2O4:Mn, as a distinct long persistent luminescence (PL) phosphor with green emission, has attracted intensive interest for display devices and security applications. We have systemically investigated the role of intrinsic defects in the PL of pristine and Mn doped ZnGa2O4 by first-principles calculations. It is found that the self-activated PL is attributed to the electron traps induced by VO and hole traps by VZn and ZnGa. The doped Mn will be energetically favored at the tetrahedral sites rather than octahedral sites under an Mn-rich condition. In contrast, the site preference of Mn largely depends on the chemical potentials of Zn and Ga under Mn-poor condition. The existence of the antisite defect ZnGa, however, promotes the stability of Mn at octahedral sites significantly, forming corresponding defect complexes. The crystal field strength is significantly enhanced, while the spin splitting is reduced on Mn in the defect complex, which introduces additional near-infrared luminescence of PL as confirmed by our experiment.
Graphene-based active frequency selective surface in microwave frequency
Authors: Zhang Heng , Hu Chenggang , Yang Jun , Tang Linlong , Huang Deping , Shao Li , Piao Mingxing , Li Chaolong , Shi Haofei
Published: March 2019

Electrical controllable charge density in graphene films has recently attracted considerable research interest for its potential applications in various active devices. In this letter, we demonstrate that graphene acts as an effective tunable loss resource to manipulate the electromagnetic response of a metallic resonant structure at microwave frequency. A transmission-tunable frequency selective surface (FSS) is realized by introducing a graphene sandwich into its near-field region. Remarkable transmission tuning from 81.7% to 25.2% at a resonant frequency of about 6.5 GHz is observed when applying bias voltage from 0 to 3.6 V. The graphene FSS prototype may open up a way for realizing electromagnetic active devices in the microwave range.
Features of fast deuterons emitted from plasma focus discharges
Authors: Kubes P. , Paduch M. , Sadowski M. J. , Cikhardt J. , Cikhardtova B. , Klir D. , Kravarik J. , Kwiatkowski R. , Munzar V. , Rezac K. , Skladnik-Sadowska E. , Szymaszek A. , Tomaszewski K. , Zaloga D. , Zielinska E.
Published: March 2019

This paper presents the discussion concerning the characteristics of the fast deuterons which have energy above 30 keV and are recorded during high-current plasma-focus (PF) discharges, by means of PM-355 plastic track-detectors placed inside ion pinhole cameras. The fast deuterons evoke D-D fusion reactions, mainly by a beam-target mechanism. The distribution of the magnetic field, which influences the trajectories of the recorded deuterons, is discussed. It is found that the fast deuterons are produced in various local sources and their motion is strongly influenced by a circular symmetry of the local magnetic field, which increases their radial shift with a decrease in their energy. The sources of these deuterons are probably located inside the plasmoids and in some local regions of the ring-shaped plasma structures. These ring-structures can be formed outside the dense pinch column, up to a radius of 5 cm. Global magnetic fields, associated with the total current flow in the PF discharge, have a weaker influence. The observed radial shift of the recorded fast deuterons is interpreted as a result of their deflection by magnetic fields which have opposite orientations of the azimuthal components, associated with the currents flowing in directions towards and from the applied ion detectors. The local sources of the recorded fast deuterons correspond to filamentary structures, in which the stored magnetic energy (having the local high density) can be released in induced electric fields accelerating the deuterons during the magnetic reconnections.
3-D underwater acoustic wave focusing by periodic structure
Authors: Ruan Yongdu , Liang Xu , Wang Zhenyu , Wang Titao , Deng Yu , Qu Fengzhong , Zhang Jun
Published: March 2019

By assembling the square lattice arrays of “+” shaped steel rods, an underwater acoustic composite lens consisting of a convex lens and a slab lens is proposed to achieve the convergence of underwater acoustic waves. In order to study the focusing ability, numerical simulations and experiments in a silencing pool are carried out among a range of frequencies between 15 kHz and 25 kHz. As a result, the 3-D underwater acoustic wave focusing is inspiringly achieved and observed. Particularly, the proposed underwater acoustic composite lens is vertically extended from a 2-D convex lens, but it is found to be able to focus waves in a three-dimensional manner. Comparisons of wave intensities and the focal distance between the numerical results and experimental results show fair agreements. These findings pave the way to the usage of superlens, hyperlens, and Luneburg lens for 3-D underwater acoustic wave focusing.
Phase transition in iterated quantum protocols for noisy inputs
Authors: Malachov Martin , Jex Igor , Kálmán Orsolya , Kiss Tamás
Published: March 2019

Quantum information processing exploits all the features quantum mechanics offers. Among them there is the possibility to induce nonlinear maps on a quantum system by involving two or more identical copies of the given system in the same state. Such maps play a central role in distillation protocols used for quantum key distribution. We determine that such protocols may exhibit sensitive, quasi-chaotic evolution not only for pure initial states but also for mixed states, i.e., the complex dynamical behavior is not destroyed by small initial uncertainty. We show that the appearance of sensitive, complex dynamics associated with a fractal structure in the parameter space of the system has the character of a phase transition. The purity of the initial state plays the role of the control parameter, and the dimension of the fractal structure is independent of the purity value after passing the phase transition point. The critical purity coincides with the purity of a repelling fixed point of the dynamics, and we show that all the pre-images of states from the close neighborhood of pure chaotic initial states have purity larger than this. Initial states from this set can be considered as quasi-chaotic.
Real and complex valued geometrical optics inverse ray-tracing for inline field calculations
Authors: Colaïtis A. , Palastro J. P. , Follett R. K. , Igumenschev I. V. , Goncharov V.
Published: March 2019

A 3-D ray based model for computing laser fields in dissipative and amplifying media is presented. The eikonal equation is solved using inverse ray-tracing on a dedicated nonstructured 3-D mesh. Inverse ray-tracing opens the possibility of using Complex Geometrical Optics (CGO), for which we propose a propagation formalism in a finite element mesh. Divergent fields at caustics are corrected using an etalon integral method for fold-type caustics. This method is successfully applied in dissipative media by modifying the ray-ordering and root selection rules, thereby allowing one to reconstruct the field in the entire caustic region. In addition, we demonstrate how caustics in the CGO framework can disappear entirely for sufficiently dissipative media, making the complex ray approach valid in the entire medium. CGO is shown to offer a more precise modeling of laser refraction and absorption in a dissipative medium when compared to Geometrical Optics (GO). In the framework of Inertial Confinement Fusion (ICF), this occurs mostly at intermediate temperatures or at high temperatures close to the critical density. Additionally, GO is invalid at low temperatures if an approximated expression of the permittivity is used. The inverse ray-tracing algorithm for GO and CGO is implemented in the IFRIIT code, in the framework of a dielectric permittivity described in 3-D using a piecewise linear approximation in tetrahedrons. Fields computed using GO and CGO are compared to results from the electromagnetic wave solver Laser Plasma Simulation Environment. Excellent agreement is obtained in 1-D linear and nonlinear permittivity profiles. Good agreement is also obtained for ICF-like Gaussian density profiles in 2-D. Finally, we demonstrate how the model reproduces Gaussian beam diffraction using CGO. The IFRIIT code will be interfaced inline to 3-D radiative hydrodynamic codes to describe the nonlinear laser plasma interaction in ICF and high-energy-density plasmas.