bluuebunny/crossref_metadata_2025 huggingface dataset:
Organocatalyzed [3+3] Annulations for the Construction of Heterocycles
Authors: Zhu Yannan , Huang You
Published: February 2020

Six-membered heterocyclic systems are widely distributed in many natural products and pharmaceuticals, and the construction of highly functionalized six-membered heterocyclic compounds is an important topic in modern organic synthesis. Organocatalyzed [3+3] annulations represents an important method for assembling a substantial variety of six-membered cycles that contain one or more heteroatoms. This review describes the development of organocatalyzed [3+3] annulations for the synthesis of six-membered heterocycles, including organocatalysis using secondary amines, tertiary amines, phosphines, chiral phosphoric acids and N-heterocyclic carbenes.

1 Introduction

2 Secondary Amine Catalyzed [3+3] Annulations

2.1 Synthesis of Nitrogen Heterocycles

2.2 Synthesis of Oxygen Heterocycles

2.3 Synthesis of Sulfur Heterocycles

3 Tertiary Amine Catalyzed [3+3] Annulations

3.1 Catalysis through Multiple Hydrogen-Bonding Interactions

3.2 Catalysis of Tertiary Amines as Lewis Bases

4 Phosphine-Catalyzed [3+3] Annulations

4.1 Synthesis of Nitrogen Heterocycles

4.2 Synthesis of Oxygen Heterocycles

4.3 Synthesis of Heterocycles Containing Two or More Heteroatoms

5 Chiral Phosphoric Acid Catalyzed [3+3] Annulations

5.1 Synthesis of Nitrogen Heterocycles

5.2 Synthesis of Heterocycles Containing Two or More Heteroatoms

6 N-Heterocyclic Carbene Catalyzed [3+3] Annulations

6.1 Synthesis of Nitrogen Heterocycles

6.2 Synthesis of Oxygen Heterocycles

6.3 Synthesis of Heterocycles Containing Two or More Heteroatoms

7 Conclusion and Outlook
Copper-Catalyzed Tandem Dehydrocyanation and [3+2] Cyclo­addition Reactions of Phenacylmalononitriles: Regioselective Synthesis of Functionalized 4-Benzoyl-5-cyanopyrazoles under Mild Conditions
Authors: Yavari Issa , Khaledian Omid
Published: February 2020

A novel copper-catalyzed [3+2] cycloaddition reaction with concomitant in situ generation of benzoylacrylonitriles and nitrile imines from phenacylmalononitriles and hydrazonoyl chlorides, respectively, is reported. The reaction was performed using copper(I) chloride as catalyst and N-methylimidazole as a clean complexing agent/weak base to afford the functionalized 4-benzoyl-5-cyanopyrazoles in moderate to good yields and excellent regioselectivity under ambient conditions. This method provides rapid access to a wide range of highly functionalized 4-benzoyl-5-cyanopyrazoles.
Beyond the Tebbe Olefination: Direct Transformation of Esters into Ketones or Alkenes
Authors: Domżalska-Pieczykolan Anna M. , Furman Bartłomiej
Published: February 2020

A direct, effective, and operationally simple transformation of esters into ketones or alkenes by the exclusive action of Tebbe’s reagent has been developed. The transformation utilizes the dual character of Tebbe’s reagent as both a methylenation agent and a rearrangement catalyst in the reaction of a wide range of substituted vinyl ethers. The resulting transformation involves sequential methylenation and rearrangement reactions and it offers a high degree of selectivity toward the synthesis of ketones or alkenes. The scope and limitations of the developed methods have been also examined.
Data-Driven Diabetes Education Guided by a Personalized Report for Patients on Insulin Pump Therapy
Authors: Groat Danielle , Corrette Krystal , Grando Adela , Vellore Vaishak , Bayuk Mike , Karway George , Boyle Mary , McCoy Rozalina , Grimm Kevin , Thompson Bithika
Published: February 2020

Objective It is difficult to assess self-management behaviors (SMBs) and incorporate them into a personalized self-care plan. We aimed to develop and apply SMB phenotyping algorithms from data collected by diabetes devices and a mobile health (mHealth) application to create patient-specific SMBs reports to guide individualized interventions. Follow-up interventions aimed to understand patient's reasoning behind discovered SMB choices.

Methods This study deals with adults on continuous subcutaneous insulin infusion using a continuous glucose monitor (CGM) who self-tracked SMBs with an mHealth application for 1 month. Patient-generated data were quantified and an SMB report was designed and populated for each participant. A diabetes educator used the report to conduct personalized, data-driven educational interventions. Thematic analysis of the intervention was conducted.

Results Twenty-two participants recorded 118 alcohol, 251 exercise, 2,661 meal events, and 1,900 photos. A patient-specific SMB report was created from this data and used to conduct the educational intervention. High variability of SMB was observed between patients. There was variability in the percentage of alcohol events accompanied by a blood glucose check, median 79% (38–100% range), and frequency of changing the bolus waveform, median 11 (7–95 range). Interventions confirmed variability of SMBs. Main emerging themes from thematic analysis were: challenges and barriers, motivators, current SMB techniques, and future plans to improve glycemic control.

Conclusion The ability to quantify SMBs and understand patients' rationale may help improve diabetes self-care and related outcomes. This study describes our first steps in piloting a patient-specific diabetes educational intervention, as opposed to the current “one size fits all” approach.
Physician Burnout and Timing of Electronic Health Record Use
Authors: Micek Mark A. , Arndt Brian , Tuan Wen-Jan , Trowbridge Elizabeth , Dean Shannon M. , Lochner Jennifer , Sampene Emmanuel , Pandhi Nancy
Published: February 2020

Background Rates of burnout among physicians have been high in recent years. The electronic health record (EHR) is implicated as a major cause of burnout.

Objective This article aimed to determine the association between physician burnout and timing of EHR use in an academic internal medicine primary care practice.

Methods We conducted an observational cohort study using cross-sectional and retrospective data. Participants included primary care physicians in an academic outpatient general internal medicine practice. Burnout was measured with a single-item question via self-reported survey. EHR time was measured using retrospective automated data routinely captured within the institution's EHR. EHR time was separated into four categories: weekday work-hours in-clinic time, weekday work-hours out-of-clinic time, weekday afterhours time, and weekend/holiday after-hours time. Ordinal regression was used to determine the relationship between burnout and EHR time categories.

Results EHR use during in-clinic sessions was related to burnout in both bivariate (odds ratio [OR] = 1.04, 95% confidence interval [CI]: 1.01, 1.06; p = 0.007) and adjusted (OR = 1.07, 95% CI: 1.03, 1.1; p = 0.001) analyses. No significant relationships were found between burnout and after-hours EHR use.

Conclusion In this small single-institution study, physician burnout was associated with higher levels of in-clinic EHR use but not after-hours EHR use. Improved understanding of the variability of in-clinic EHR use, and the EHR tasks that are particularly burdensome to physicians, could help lead to interventions that better integrate EHR demands with clinical care and potentially reduce burnout. Further studies including more participants from diverse clinical settings are needed to further understand the relationship between burnout and after-hours EHR use.
Unusual MR Imaging Features in CT Hyperdense Posterior Fossa Dermoids: Report of Two Cases
Authors: Sathiaprabhu Anbazhagan , Sravani Nichanametla , Nagarajan Krishnan , Sabarish Sekar , Patil Kapil
Published: February 2020

Dermoids, either intracranial or in the rest of the body, usually have typical imaging findings due to their fat contents as fat density in computed tomography (CT) and T1- and T2-hyperintensity in magnetic resonance imaging (MRI). Variable imaging appearances have been described due to soft tissue contents, hair, calcification, or even tooth. Posterior fossa dermoids have been reported as a specific variant that shows hyperdensity in CT and mixed signal intensity in MRI. We report two cases of posterior fossa CT hyperdense dermoids that showed unusual MRI features in the form of signal loss in magnetization transfer images and lipid peak in magnetic resonance spectroscopy. Both patients underwent surgical resection and histopathological confirmation and the causes of this unusual imaging appearance are discussed.
A tunable double negative device consisting of a plasma array and a negative-permeability metamaterial
Authors: Iwai Akinori , Righetti Fabio , Wang Benjamin , Sakai Osamu , Cappelli Mark A.
Published: February 2020

Extraordinary wave transmission is demonstrated through a double-negative composite comprised of a negative-permeability array of double split ring resonators and a negative-permittivity array of plasma discharge tubes at microwave frequencies. A transmission peak emerges in a double-negative band and controlling the electron density inside the plasma tubes dynamically regulates the transmission properties. By performing experiments and theoretical calculations, we verify that the composite permits wave propagation with negative permeability and controllable permittivity, which indicates that a tunable negative-refractive-index device is achieved.
Active narrowband filter based on inductance and capacitance for low-frequency applications
Authors: Burd A. , Suchenek M.
Published: February 2020

Most analog filter solutions operating in the kilohertz frequency range are based on RC elements. However, it is not possible to design a very narrow filter (high q-factor around 1000) by using this architecture. In this article, we would like to show a filter implemented based on a simple series LC resonance circuit (consisting of just an inductor and a capacitor) and an analog circuit. The designed filter based on these elements can be more selective than a typical active filter based on RC elements (resistor and capacitor). Performed measurements confirmed the correct operation of the filter, where the designed filter q-factor was ∼591 at a resonant frequency of 4.73 kHz.
Spectral energy distribution of the equilibrium radiation and its asymptotic behavior in ideal gaseous plasmas
Authors: Bobrov V. B. , Trigger S. A. , Sokolov I. M.
Published: February 2020

It is shown that the difference between the Planck distribution and the spectral energy distribution of the equilibrium radiation in a homogeneous and isotropic material medium is completely determined by the transverse dielectric permittivity of the material medium. In contrast with the well known approach for the generalized spectral energy distribution of the equilibrium radiation in a plasma medium based on accounting only the frequency dependence of the dielectric permittivity, the crucial role of both the frequency and the spatial dispersions of the transverse dielectric permittivity is demonstrated. On this basis, the high-frequency and the low-frequency asymptotical properties of the spectral energy distribution in an ideal gaseous plasma are considered. The obtained results for the equilibrium spectral distribution are principally different from the corresponding asymptotic of the Planck distribution, possessing a long tail at the high frequency and a logarithmical increase at the low frequency.
Effect of A-site ionic disorder on the structure, magnetic, and magnetocaloric properties of La0.7−xNdxCa0.3−y(Ba,Sr)yMnO3
Authors: Chen Peiqi , He Wei , Xiao Guorui , Wen Jingxian , Yang Tonghan , Wu Xiaowei , Wang Tao
Published: February 2020

The effects of A-site cation size mismatch on La0.7 − xNdxCa0.3 − y(Ba,Sr)yMnO3 perovskite materials with a constant A-site average ionic radius ⟨rA⟩ = 1.2052 Å have been investigated. Polycrystalline samples have been prepared through the standard solid-state reaction method at high temperatures, and their structures, magnetic properties, and magnetocaloric effect (MCE) have been investigated in detail. X-ray diffraction patterns show that all of the samples crystallized in an orthorhombic structure with the space group Pnma. XPS analysis confirmed the Mn3+/Mn4+ ratio remained constant as σ2 was varied. Meanwhile, upon increasing σ2 from 0.0002 to 0.007, the Curie temperature (TC) decreased linearly from 254 K to 108 K. Based on M-H isotherms, Arrott plots and the maximum magnetic entropy prove a crossover of first-to-second-order transition with increasing σ2. Samples with σ2 = 0.0002, 0.001, and 0.003 exhibited a first-order transition and had larger MCEs than those showing a second-order transition.
Design, construction, and operation of an 18 T 70 mm no-insulation (RE)Ba2Cu3O7−x magnet for an axion haloscope experiment
Authors: Kim Jaemin , Kim Yungil , Yoon Sangwon , Shin Kanghwan , Lee Junghun , Jung Jong Seop , Lee Jung Tae , Kim Jin-Geun , Kim Donglak , Yoo Jonghee , Lee Hunju , Moon Seung-Hyun , Hahn Seungyong
Published: February 2020

We report the design, construction, and operation results of an 18 T 70 mm cold-bore high temperature superconductor (HTS) no-insulation (NI) magnet, which is developed for an axion haloscope experiment. The magnet consists of 44 double-pancake coils wound with multi-width and multi-thickness REBa2Cu3O7−x (RE = rare earth) tapes. Owing to the NI feature, the magnet is highly compact; is 162 mm in outer diameter and 476 mm tall; and provides an environment of 0.22 T2 m3 within the cold-bore target space of 66 mm in diameter and 200 mm in length. After an initial performance test at SuNAM Co. Ltd., the magnet was installed at the Center for Axion and Precision Physics Research (CAPP) of the Institute for Basic Science in Daejeon, South Korea, in August 2017. The magnet has been successfully operating at the CAPP since then, except for maintenance in October 2018. The magnet may represent the first high field HTS user magnet that experienced long-term operation of over one year.
Electronic circuit for measuring the current slope (dI/dt) and the post-arc current in gas-filled circuit breakers
Authors: Votteler T. , Stoller P.
Published: February 2020

We have developed an electronic circuit for measuring the slope of the current near the current-zero crossing of an alternating current (dI/dt) and the post-arc current in gas-filled circuit breakers. The dI/dt and the post-arc current are measured in the current injection loop of a Weil–Dobke circuit (a synthetic test circuit that consists of a loop to generate a high short-circuit current at a relatively low voltage and a separate loop to generate high voltage after the short-circuit current is interrupted). The arc voltage and the dI/dt can be used to calculate the arc resistance of a breaker; the arc resistance and the post-arc current of the breaker provide important information about its interruption performance. The dI/dt and the post-arc current are measured with a commercially available high frequency coaxial shunt. The output voltage of the shunt is limited by using an electronic circuit to achieve better accuracy in the low current regime. The limited voltage signal is amplified with an operational amplifier that acts as a line driver. The prototype has a bandwidth of 12 MHz (+0.005 dB/−0.1 dB) and a propagation delay time of 10 ns. The nominal input voltage is ±50 V, and the maximum dU/dt (slope of the input voltage) that can be measured is 700 mV/μs with a linear range of ±0.6 V. Post-arc currents down to 200 mA can be measured.
Basic factors for acquiring, correcting, and interpreting probe current-voltage characteristic in moderate-collisional plasma for determining electron energy distribution
Authors: Demidov V. I. , Koepke M. E. , Kurlyandskaya I. P. , Malkov M. A.
Published: February 2020

Methods for inferring the electron distribution function (EDF) from a probe current–voltage trace are reviewed for moderate-collisional plasma. The explicit accounting of particle collisions, modeling sheath depletion, and electron refilling processes are rarely performed when analyzing probe measurements, yet they are critical for regime validity, EDF-profile accuracy, and space potential quantification precision. The advantages, limitations, and utilization of large-area wall probes in moderate-collisional plasma, capable of highly resolved indications of energetic electrons in plasma, are outlined.
The preliminary test of multi-charged ions generation with a 2.45 GHz microwave-driven ion source
Authors: Ma TengHao , Peng ShiXiang , Zhang JingFeng , Wu WenBin , Jiang YaoXiang , Ren HaiTao , Xu Yuan , Sun Jiang , Li Kai , Guo ZhiYu , Chen JiaEr
Published: February 2020

A 2.45 GHz microwave-driven ion source for the generation of multicharged ions has been designed and built at Peking University recently. The magnetic field configuration of this ion source is a minimum-B type with a combination of a hexapole field and an axial mirror field. Argon was selected as the first tested beam generated by this ion source. A 63 µA Ar4+ ion beam at 35 kV extraction voltage was obtained in the pulsed mode (50 Hz/500 µs). Without the hexapole magnetic field, the highest charge state was only Ar2+, and no Ar4+ ion beam was detected. The comparison between the two sets of experimental results with different magnetic configurations has proven the rationality of the production of multicharged ions with this ion source. Both experimental results and discussion will be presented in this paper.
Understanding ICF hohlraums using NIF gated laser-entrance-hole images
Authors: Chen Hui , Woods D. T. , Jones O. S. , Benedetti L. R. , Dewald E. L. , Izumi N. , MacLaren S. A. , Meezan N. B. , Moody J. D. , Palmer N. E. , Schneider M. B. , Vandenboomgaerde M.
Published: February 2020

The newly available ns-gated laser-entrance-hole (LEH) imager on the National Ignition Facility provides routine, non-perturbative measurements of the x-ray emission from laser-heated plasmas inside the hohlraum as viewed at 19° to the hohlraum axis through one of its LEHs. Multiple images are acquired for a series of times and filter-selected x-ray energy bands within a single shot. The images provide time dependent data on phenomena including the effective radius of the LEH, the length of the gold-plasma “bubble” evolving off the interior wall surface heated by the outer beams, the evolving radius of the x-ray heated hohlraum wall, and the radius of the ablation front of the fusion capsule. These measurements are explained and illustrated with sample data. These techniques are then applied to understand hohlraum behavior as a function of gas fill. For hohlraums with helium gas fill densities of 0.15 to 0.30 mg/cm3, synthetic images computed from simulations agree well with experimental gated LEH images when an inhibited heat transport model [Jones et al., Phys. Plasmas 24, 056312 (2017)] is used. This model can be adjusted to reproduce the expansion rate of the laser-heated plasma bubble in such a way as to improve agreement with the images. At the higher 0.6 mg/cc gas fill, the experimental images show more pronounced 3D features, resulting in slightly less good agreement with the 2D simulations.
Mass splitting in the Thomas–Fermi–Dirac–von Weizsäcker model with background potential
Authors: Aguirre Salazar Lorena , Alama Stan , Bronsard Lia
Published: February 2020

We consider minimization problems of the Thomas–Fermi–Dirac–von Weizsäcker (TFDW) type in which the Newtonian potential is perturbed by a background potential satisfying mild conditions, which ensures the existence of minimizers. We describe the structure of minimizing sequences for those variants and obtain a more precise characterization of patterns in minimizing sequences for the TFDW functionals regularized by long-range perturbations.
Spatial heterogeneity may form an inverse camel shaped Arnol’d tongue in parametrically forced oscillations
Authors: Edri Yuval , Meron Ehud , Yochelis Arik
Published: February 2020

Frequency locking in forced oscillatory systems typically organizes in “V”-shaped domains in the plane spanned by the forcing frequency and amplitude, the so-called Arnol’d tongues. Here, we show that if the medium is spatially extended and monotonically heterogeneous, e.g., through spatially dependent natural frequency, the resonance tongues can also display “U” and “W” shapes; we refer to the latter as an “inverse camel” shape. We study the generic forced complex Ginzburg–Landau equation for damped oscillations under parametric forcing and, using linear stability analysis and numerical simulations, uncover the mechanisms that lead to these distinct resonance shapes. Additionally, we study the effects of discretization by exploring frequency locking of oscillator chains. Since we study a normal-form equation, the results are model-independent near the onset of oscillations and, therefore, applicable to inherently heterogeneous systems in general, such as the cochlea. The results are also applicable to controlling technological performances in various contexts, such as arrays of mechanical resonators, catalytic surface reactions, and nonlinear optics.
Achievement of high power and long pulse negative ion beam acceleration for JT-60SA NBI
Authors: Hiratsuka J. , Kashiwagi M. , Ichikawa M. , Umeda N. , Saquilayan G. Q. , Tobari H. , Watanabe K. , Kojima A. , Yoshida M.
Published: February 2020

Long pulse acceleration of hydrogen negative ion beams with the power density over 70 MW/m2 and the pulse length over 100 s has been demonstrated for the first time by using a multi-aperture 3-stage accelerator. Such long pulse acceleration was achieved by integrating the design of beam optics and voltage holding capability to meet the requirements of JT-60SA. By using the newly designed accelerator for JT-60SA, voltage holding at 500 kV with beam acceleration was stably sustained even after 5 g of cesium was seeded, and heat load on each acceleration grid was reduced below the allowable level for long pulse, less than 5% of total acceleration power. As a result, 500 keV, 154 A/m2 for 118 s beam acceleration was achieved, which satisfies the requirement of the negative ion source for JT-60SA. This pulse length of such high-power density beams is longest in the world. In addition, the result contributes to the long pulse acceleration of multi-stage electrostatic accelerators, such as 1 MeV negative ion accelerator for ITER.
2D modeling of fusion ignition conditions for a multilayer plasma liner magneto-inertial fusion target in a cylindrical configuration
Authors: Thompson Seth , Cassibry Jason
Published: February 2020

A set of 2D time dependent simulations of an imploding cylindrical target and liner is presented. These simulations were performed using an ideal magnetohydrodynamic methodology that augmented the energy equation to account for fusion alpha particle deposition, thermal conduction, and Bremsstrahlung radiation. A reference case of a deuterium and tritium (DT) target compressed by a multilayer liner consisting of an inner layer of DT and an outer layer of argon was evaluated. The reference case was chosen to be within the region of positive fusion heating predicted by the Lindl–Widner power balance model. Analysis of the reference case determined fusion gains of three or greater can be achieved. A sensitivity analysis of four parameters was performed. These parameters were the target: radius, density, temperature, and inner/outer liner thickness ratio. It was found that the Lindl–Widner parameter space accurately predicts regions of positive fusion heating, but over-predicts the effects of mechanical work done by a plasma liner. It was determined that a plasma liner could be used as a confinement mechanism to contain a thermally conditioned target and allow it to ignite and burn. Thermal conduction from the hot fusing target was capable of heating the inner liner layer to fusion ignition conditions and increasing the fusion yield.
Environmental chamber with controlled temperature and relative humidity for ice crystallization kinetic measurements by atomic force microscopy
Authors: Gianetti Melisa M. , Gelman Constantin Julián , Corti Horacio R. , Longinotti M. Paula
Published: February 2020

The present work describes the development of an environmental chamber (EC), with temperature and humidity control, for measuring ice growth kinetics over a substrate with an atomic force microscope (AFM). The main component of the EC is an AFM fluid glass cell. The relative humidity (RH) inside the EC is set by the flow of a controlled ratio of dry and humid nitrogen gases. The sample temperature is fixed with an AFM commercial accessory, while the temperature of the nitrogen gas inside the EC is controlled by circulating cold nitrogen vapor through a copper cooler, specially designed for this purpose. With this setup, we could study the growth rate of ice crystallization over a mica substrate by measuring the force exerted between the tip and the sample when they approach each other as a function of time. This experimental development represents a significant improvement with respect to previous experimental determinations of ice growth rates, where RH and temperature of the air above the sample were determined far away from the ice crystallization regions, in opposition to the present work.
Charge exchange recombination spectroscopy at Wendelstein 7-X
Authors: Ford O. P. , Vanó L. , Alonso J. A. , Baldzuhn J. , Beurskens M. N. A. , Biedermann C. , Bozhenkov S. A. , Fuchert G. , Geiger B. , Hartmann D. , Jaspers R. J. E. , Kappatou A. , Langenberg A. , Lazerson S. A. , McDermott R. M. , McNeely P. , Neelis T. W. C. , Pablant N. A. , Pasch E. , Rust N. , Schroeder R. , Scott E. R. , Smith H. M. , Wegner Th. , Kunkel F. , Wolf R. C. ,   W7-X Team
Published: February 2020

The Charge Exchange Recombination Spectroscopy (CXRS) diagnostic has become a routine diagnostic on almost all major high temperature fusion experimental devices. For the optimized stellarator Wendelstein 7-X (W7-X), a highly flexible and extensive CXRS diagnostic has been built to provide high-resolution local measurements of several important plasma parameters using the recently commissioned neutral beam heating. This paper outlines the design specifics of the W7-X CXRS system and gives examples of the initial results obtained, including typical ion temperature profiles for several common heating scenarios, toroidal flow and radial electric field derived from velocity measurements, beam attenuation via beam emission spectra, and normalized impurity density profiles under some typical plasma conditions.
Planar Hall effect in PtSe2
Authors: Li Zhaoguo , Xiao Tingting , Zou Ruijiao , Li Jia , Zhang Yingjuan , Zeng Yong , Zhou Minjie , Zhang Jicheng , Wu Weidong
Published: February 2020

In this study, we report on the planar Hall transport study of type-II Dirac semimetal PtSe2 microflakes. The remarkable anisotropic magnetoresistance (AMR) and giant planar Hall resistance (PHR) are observed while tilting the magnetic field away from the current direction in the sample plane. Both AMR and PHR oscillate with the in-plane angle between the magnetic field and current, and the oscillation period is π. The angular dependence of AMR and PHR can be perfectly described by the theoretical formulas. The physical mechanism behind the observed AMR and PHR may have resulted from the classical orbital magnetoresistance.
The diffusion limit of ballistic transport in the scrape-off layer
Authors: Manz P. , Hufnagel C. , Zito A. , Carralero D. , Griener M. , Lunt T. , Pan O. , Passoni M. , Tal B. , Wischmeier M. , Wolfrum E. ,   ASDEX Upgrade Team
Published: February 2020

At least the far scrape-off layer of magnetically confined fusion plasmas transport is intermittent and non-diffusive as observed by the appearance of plasma filaments. Transport codes using effective diffusion coefficients are still the main workhorse investigating the scrape-off layer and divertor regions. An effective perpendicular diffusion coefficient for intermittent filamentary dominated perpendicular transport in the scrape-off layer is motivated by the telegraph equation, describing an exponentially decaying correlated random walk. On short time scales, the telegraph equation describes the ballistic transport of filamentary structures with a typical velocity ub and correlation time τ. In stationary conditions, the corresponding diffusion coefficient is given by ub2τ. Since ub and τ can be determined experimentally, it is proposed to use ub2τ as an input for modeling or for interpretation of perpendicular transport in the far scrape-off layer.
Set–reset latch logic operation in a bistable system under suprathreshold and subthreshold signals
Authors: Gui Rong , Zhang Huiyu , Cheng Guanghui , Yao Yuangen
Published: February 2020

A set–reset latch is a basic building block of computers and can be used to store state information. Here, by testing the influence of the two logical input signals on the reliable set–reset latch logic operation in the bistable system, we found that there are two types of input signals, namely, suprathreshold and subthreshold signals. For the suprathreshold signals, reliable set–reset logic operation can be achieved without any driving forces and exhibits certain anti-interference ability; for the subthreshold signals, a single harmonic could induce correct set–reset latch logic operation but with a narrow optimal parameter region. The introduction of biharmonic-induced set–reset latch logic operation (logical vibrational resonance) could greatly expand the parameter region. Explanations for the above results were provided by taking the logical inputs as the dynamic bias to analyze the dynamic changes in the system. Finally, the results were further verified by circuit simulation and actual hardware circuit.
Ordered graphitic microfoams via shrinkage and catalytic conversion of polymer scaffolds
Authors: Nakanishi Kenichi , Hofmann Stephan
Published: February 2020

Carbon foams are a highly attractive class of low-density materials whose structural, electrical, thermal, and chemical properties are strongly linked to the level of graphitization and 3D structure. Pyrolytic graphitization requires very high temperatures (>2000 °C), and most current graphitic foams are stochastically arranged with restricted control over pore size and architecture. We report on the shrinkage and catalytic conversion of commercial polymer foams and 3D printed templates as a facile, cost-effective method to scalably reach and control sub-200 μm unit cell sizes and a high level of graphitization at temperatures below 1100 °C. We demonstrate the conversion of 3D printed cubic polymer lattices to an identically shaped carbonaceous network with shrinkage controlled via an atomic layer deposited oxide coating up to a maximum 125 fold decrease in volume and over 95% mass loss through slow carbonization. This is accompanied by a reduction in the unit cell size from 1000 µm to 170 µm and strut widths from 550 µm to 65 µm. The structures are subsequently coated with a sacrificial metal catalyst by electroless deposition to achieve efficient graphitization while maintaining structural order. We discuss the underlying mechanisms and opportunities to tailor the processes and structure to manifold application needs.
Measurements of elastoresistance under pressure by combining in-situ tunable quasi-uniaxial stress with hydrostatic pressure
Authors: Gati Elena , Xiang Li , Bud’ko Sergey L. , Canfield Paul C.
Published: February 2020

Uniaxial stress, as well as hydrostatic pressure are often used to tune material properties in condensed matter physics. Here, we present a setup that allows for the study of the combined effects of quasi-uniaxial stress and hydrostatic pressure. Following earlier designs for measurements under finite stress at ambient pressures [e.g., Chu et al., Science 337, 710 (2012)], the present setup utilizes a piezoelectric actuator to change stress in situ inside the piston–cylinder pressure cell. We show that the actuator can be operated over the full temperature (from 30 K up to 260 K) and pressure range (up to ≈2 GPa), resulting in a clear and measurable quasi-uniaxial strain. To demonstrate functionality, measurements of the elastoresistance (i.e., the change of resistance of a sample as a response to quasi-uniaxial strain) under finite hydrostatic pressure on the iron-based compound BaFe2As2 are presented as a proof-of-principle example and discussed in the framework of electronic nematicity. Overall, this work introduces the combination of in situ tunable quasi-uniaxial stress and large (up to ≈2 GPa) hydrostatic pressure as a powerful combination in the study of novel electronic phases. In addition, it also points toward further technical advancements which can be made in the future.
Crystallization of TiO2 polymorphs from RF-sputtered, amorphous thin-film precursors
Authors: Agirseven O. , Rivella D. T. , Haggerty J. E. S. , Berry P. O. , Diffendaffer K. , Patterson A. , Kreb J. , Mangum J. S. , Gorman B. P. , Perkins J. D. , Chen B. R. , Schelhas L. T. , Tate J.
Published: February 2020

Crystalline TiO2 films of anatase, brookite, and rutile are reproducibly made from amorphous precursors deposited by RF magnetron sputtering, producing large-area, single phase films of uniform thickness. Sputtered amorphous TiO2 precursor thin films follow the general behavior observed for amorphous precursor thin films generated by pulsed laser deposition, namely, that oxygen deficiency is necessary for the formation of brookite and rutile. We quantify the oxygen deficiency and correlate it with the long wavelength optical absorption. We find that the precursor deposition rate is also a contributing factor to phase selection and that brookite and rutile form from films deposited more rapidly and anatase from films deposited more slowly. Sputtered and pulsed laser deposited amorphous precursor films prepared with similar oxygen deficiency and similar thickness result in the same final state after annealing, but the rate for sputtered precursors is slower.
Study of droplet splashing on a liquid film with a tunable surface tension pseudopotential lattice Boltzmann method
Authors: Yuan Hao , Li Junna , He Xiaolong , Chen Liang , Wang Zhaobing , Tan Jiawan
Published: February 2020

A tunable surface tension pseudopotential lattice Boltzmann method (LBM) with an axisymmetric boundary is applied to study a droplet splashing on a thin film. Our work focused on the crown behavior influenced by the different parameters, including the Reynolds number, Weber number, liquid film thickness, and gravity acceleration. In addition, the total kinetic energy of the crown is proposed to explain the evolution of the crown shape from the perspective of energy. Based on the achieved results, it is found that the crown radius changes with time are unaffected by these parameters and consistent with the power-law in previous studies. However, the height of the crown and the satellite droplet formation process are affected by the referred parameters. Besides, it is found that the energy consumption during the collapse process and splash angle are two key factors affecting the height of the crown. There is a threshold liquid film thickness with the maximum height of the crown, which is between 0.2 and 0.25 times the droplet radius. This study shows that the proposed LBM pseudopotential model is a robust and effective tool for the study of the droplet splashing on the thin film and has the potential to predict the droplet splashing phenomena in the presence of complex boundaries.
Disentangling different modes of mobility for triphenylphosphine oxide adsorbed on alumina
Authors: Hubbard Patrick J. , Benzie Jordon W. , Bakhmutov Vladimir I. , Blümel Janet
Published: February 2020

Triphenylphosphine oxide (TPPO, 1) has been adsorbed on neutral alumina by dry grinding of the components in the absence of a solvent. The adsorption proves translational mobility of 1 on the surface of alumina. Different surface coverages from a densely packed monolayer (99% coverage) to a dilute sub-monolayer (25%) have been produced. The samples have been studied by diverse multinuclear 1H, 13C, and 31P variable temperature solid-state nuclear magnetic resonance (NMR) techniques. The interactions of 1 with the surface are determined by hydrogen bonding of the P=O group to OH groups on the surface. The 31P solid-state NMR spectra prove that even at low temperatures, the molecules of 1 are highly mobile on the surface. Using T1 and T2 relaxation time analyses of the 31P resonance in the solid state at variable temperatures allowed the identification and quantification of two different modes of mobility. Besides the translational mobility that consists of jumps from one hydrogen-bonding OH site on the surface to an adjacent one, a rotational movement around the axis defined by the P=O group of 1 occurs.
Signatures of temperature driven antiferromagnetic transition in the electronic structure of topological insulator MnBi2Te4
Authors: Estyunin D. A. , Klimovskikh I. I. , Shikin A. M. , Schwier E. F. , Otrokov M. M. , Kimura A. , Kumar S. , Filnov S. O. , Aliev Z. S. , Babanly M. B. , Chulkov E. V.
Published: February 2020

In this work, we employed angle resolved photoemission spectroscopy (ARPES) to analyze the temperature dependent changes in the electronic structure of the first antiferromagnetic topological insulator MnBi2Te4 upon crossing the Néel temperature TN ≈ 25 K. We observed an exchange splitting of the bulk conduction band, which has a power law dependence on temperature (1−T/T0)2β with an onset temperature T0 well matching the measured bulk TN. We found a matching temperature evolution of the topological surface states integrated spectral weight in the vicinity of the Dirac point. Furthermore, we observed an additional quasi-2D state with Rashba-type splitting, which is also affected by the emerged magnetism and exhibits an opening of a gap, reminiscent of the effect of an out-of-plane magnetic field, below TN. All these findings point toward strong evidence of the interplay between emerged magnetism with bulk and topological surface states. The observed temperature-dependent effects in MnBi2Te4 may be used as an experimental fingerprint for the presence of magnetism and may guide the future analysis of ARPES spectra in magnetic topological insulators.
Long-term stabilization of carrier envelope phases of mid-infrared pulses for the precise detection of phase-sensitive responses to electromagnetic waves
Authors: Yamakawa T. , Sono N. , Kitao T. , Morimoto T. , Kida N. , Miyamoto T. , Okamoto H.
Published: February 2020

We report a high performance mid-infrared pump visible probe measurement system, which can measure phase-sensitive responses to a mid-infrared pulse along the oscillating electromagnetic field. In this system, the pump light is a phase-locked mid-infrared pulse with a temporal width of 100 fs, which is produced via difference frequency generation (DFG) from two idler pulses of two optical parametric amplifiers (OPAs) that are excited by the same Ti:sapphire regenerative amplifier. The probe pulse is a visible pulse with a temporal width of 9 fs and is generated from a custom-built non-collinear OPA. By measuring the electric-field waveforms of mid-infrared pump pulses with electro-optic sampling and evaluating their carrier envelope phase (CEP) and the temporal positions of their envelopes relative to ultrashort visible probe pulses, we are able to perform double feedback corrections that eliminate both the following sources of drift. The CEP drift in mid-infrared pulses originating from fluctuations in the difference of optical-path lengths of the two idler pulses before the DFG is corrected by inserting a wedge plate in one idler path, and the drift in pump–probe delay times due to fluctuations in the difference of the overall optical-path lengths of the pump and probe pulses is corrected with mechanical delay lines. In this double feedback system, the absolute carrier phase of mid-infrared pulses can be fixed within 200 mrad and errors in the measurement of phase-sensitive responses can be reduced to within 1 fs over a few tens of hours.
Transforming growth factor-β superfamily and interferon-τ in ovarian function and embryo development in female cattle: review of biology and application
Authors: D'Occhio Michael J. , Campanile Giuseppe , Baruselli Pietro S.
Published: February 2020

Survival of the embryo and establishment of a pregnancy is a critical period in the reproductive function of female cattle. This review examines how the transforming growth factor-β (TGFB) superfamily (i.e. bone morphogenetic protein (BMP) 15, growth differentiation factor (GDF) 9, anti-Müllerian hormone (AMH)) and interferon-τ (IFNT) affect ovarian function and embryo development. The oocyte in a primary follicle secretes BMP15 and GDF9, which, together, organise the surrounding granulosa and theca cells into the oocyte–cumulus–follicle complex. At the same time, the granulosa secretes AMH, which affects the oocyte. This autocrine–paracrine dialogue between the oocyte and somatic cells continues throughout follicle development and is fundamental in establishing the fertilisation potential and embryo developmental competency of oocytes. The early bovine embryo secretes IFNT, which acts at the uterine endometrium, corpus luteum and blood leucocytes. IFNT is involved in the maternal recognition of pregnancy and immunomodulation to prevent rejection of the embryo, and supports progesterone secretion. Manipulation of BMP15, GDF9, AMH and IFNT in both invivo and invitro studies has confirmed their importance in reproductive function in female cattle. This review makes the case that a deeper understanding of the biology of BMP15, GDF9, AMH and IFNT will lead to new strategies to increase embryo survival and improve fertility in cattle. The enhancement of oocyte quality, early embryo development and implantation is considered necessary for the next step change in the efficiency of natural and assisted reproduction in cattle.
Selective targeting of TET catalytic domain promotes somatic cell reprogramming
Authors: Singh Anup Kumar , Zhao Bo , Liu Xiuhua , Wang Xin , Li Hongzhi , Qin Hanjun , Wu Xiwei , Ma Yuelong , Horne David , Yu Xiaochun
Published: February 2020

Ten-eleven translocation (TET) family enzymes (TET1, TET2, and TET3) oxidize 5-methylcytosine (5mC) and generate 5-hydroxymethylcytosine (5hmC) marks on the genome. Each TET protein also interacts with specific binding partners and partly plays their role independent of catalytic activity. Although the basic role of TET enzymes is well established now, the molecular mechanism and specific contribution of their catalytic and noncatalytic domains remain elusive. Here, by combining in silico and biochemical screening strategy, we have identified a small molecule compound, C35, as a first-in-class TET inhibitor that specifically blocks their catalytic activities. Using this inhibitor, we explored the enzymatic function of TET proteins during somatic cell reprogramming. Interestingly, we found that C35-mediated TET inactivation increased the efficiency of somatic cell programming without affecting TET complexes. Using high-throughput mRNA sequencing, we found that by targeting 5hmC repressive marks in the promoter regions, C35-mediated TET inhibition activates the transcription of the BMP-SMAD-ID signaling pathway, which may be responsible for promoting somatic cell reprogramming. These results suggest that C35 is an important tool for inducing somatic cell reprogramming, as well as for dissecting the other biological functions of TET enzymatic activities without affecting their other nonenzymatic roles.
Packing structure of semiflexible rings
Authors: Gómez Leopoldo R. , García Nicolás A. , Pöschel Thorsten
Published: February 2020

Unraveling the packing structure of dense assemblies of semiflexible rings is not only fundamental for the dynamical description of polymer rings, but also key to understand biopackaging, such as observed in circular DNA of viruses or genome folding. Here we use X-ray tomography to study the geometrical and topological features of disordered packings of rubber bands in a cylindrical container. Assemblies of short bands assume a liquid-like disordered structure, with short-range orientational order, and reveal only minor influence of the container. In the case of longer bands, the confinement causes folded configurations and the bands interpenetrate and entangle. Most of the systems are found to display a threading network which percolates the system. Surprisingly, for long bands whose diameter is more than twice the diameter of the container, we found that all bands interpenetrate each other, in a complex fully entangled structure.
Dynamic clamp constructed phase diagram for the Hodgkin and Huxley model of excitability
Authors: Ori Hillel , Hazan Hananel , Marder Eve , Marom Shimon
Published: February 2020

Excitability—a threshold-governed transient in transmembrane voltage—is a fundamental physiological process that controls the function of the heart, endocrine, muscles, and neuronal tissues. The 1950s Hodgkin and Huxley explicit formulation provides a mathematical framework for understanding excitability, as the consequence of the properties of voltage-gated sodium and potassium channels. The Hodgkin–Huxley model is more sensitive to parametric variations of protein densities and kinetics than biological systems whose excitability is apparently more robust. It is generally assumed that the model’s sensitivity reflects missing functional relations between its parameters or other components present in biological systems. Here we experimentally assembled excitable membranes using the dynamic clamp and voltage-gated potassium ionic channels (Kv1.3) expressed in
Xenopus
oocytes. We take advantage of a theoretically derived phase diagram, where the phenomenon of excitability is reduced to two dimensions defined as combinations of the Hodgkin–Huxley model parameters, to examine functional relations in the parameter space. Moreover, we demonstrate activity dependence and hysteretic dynamics over the phase diagram due to the impacts of complex slow inactivation kinetics. The results suggest that maintenance of excitability amid parametric variation is a low-dimensional, physiologically tenable control process. In the context of model construction, the results point to a potentially significant gap between high-dimensional models that capture the full measure of complexity displayed by ion channel function and the lower dimensionality that captures physiological function.
From pedagogical input to learner output
Authors: Möller Verena
Published: February 2020

English as a Foreign Language (EFL) materials have often been criticized for a lack of
authenticity. However, their direct impact on learner language has rarely been assessed. We compare pedagogical input from EFL and
Content and Language Integrated Learning (CLIL) materials to texts produced by learners taught via the
textbooks in question. The analysis of corpus
data showed that EFL textbooks did not systematically differ from CLIL materials in terms of conditional frequency and verb forms
combinations. No significant difference was detected for CLIL and non-CLIL learner texts either. Both groups did, however, deviate
from novice native writing in that conditionals expressing low hypotheticality were overrepresented while conditionals expressing
a higher level of hypotheticality were underrepresented and frequently erroneous. Misrepresentations revealed for EFL textbooks in
previous research were found to match the deviations in learner language in a way that aids L2 development rather than impairing
it. Hence, fundamental changes are not required, even though more studies should be undertaken to investigate the direct impact of
teaching materials on learner output.