bluuebunny/crossref_metadata_2025 huggingface dataset:
Kernel methods for detecting coherent structures in dynamical data
Authors: Klus Stefan , Husic Brooke E. , Mollenhauer Mattes , Noé Frank
Published: December 2019

We illustrate relationships between classical kernel-based dimensionality reduction techniques and eigendecompositions of empirical estimates of reproducing kernel Hilbert space operators associated with dynamical systems. In particular, we show that kernel canonical correlation analysis (CCA) can be interpreted in terms of kernel transfer operators and that it can be obtained by optimizing the variational approach for Markov processes score. As a result, we show that coherent sets of particle trajectories can be computed by kernel CCA. We demonstrate the efficiency of this approach with several examples, namely, the well-known Bickley jet, ocean drifter data, and a molecular dynamics problem with a time-dependent potential. Finally, we propose a straightforward generalization of dynamic mode decomposition called coherent mode decomposition. Our results provide a generic machine learning approach to the computation of coherent sets with an objective score that can be used for cross-validation and the comparison of different methods.
Characteristics of ferroelectric field effect transistors composed of a ferroelectric Bi3TaTiO9 gate stack and a single-layer MoS2 channel
Authors: Shin Hyun Wook , Lee Sung-Hoon , Son Jong Yeog
Published: December 2019

Polycrystalline Bi3TaTiO9 (BTTO) thin films of layered perovskite ferroelectric materials were deposited on a Pt/Ta/glass substrate via a pulsed laser deposition (PLD) method using two different PLD deposition rates of 0.03 and 0.5 nm/pulse under the same substrate temperature conditions. The BTTO thin film grown by the low PLD deposition rate exhibited a highly a-oriented crystal structure, which was confirmed by X-ray diffraction experiments. The crystallinity of the a-oriented film caused an improvement in the ferroelectric polarization and piezoelectric coefficients; at the same time, the leakage current characteristics were slightly deteriorated. Ferroelectric field effect transistors (FeFETs), made of monolayer MoS2 channels and BTTO thin films as a gate dielectric layer, exhibited clearly different memory windows as a nonvolatile memory. In addition, the reliability of the FeFETs was confirmed by fatigue tests up to 1012 switching cycles and retention tests up to 106 s.
Nonlinear evolution of energetic-particles-driven waves in dissipative plasma
Authors: Li Shuhan , Liu Jinyuan , Wang Feng , Shen Wei , Li Dong
Published: December 2019

The formation of holes and clumps has been investigated by using a one-dimensional electrostatic particle-in-cell code with the effect of background dissipation and dynamical friction. The results show that the background dissipation is the primary reason for frequency sweeping, and dynamical friction can enhance the frequency sweeping in the damped case. A finite velocity distribution of energetic particles (EPs) can modulate the range of frequency sweeping. The evolution of continuous formation of holes and clumps is observed in phase space. The central islands are torn in two parts, which shift away from the resonance center, and afterward, new central islands reappear. Finally, multiple modes resonating with energetic particles with damping are investigated. The results indicate that there is a nonlinear wave-wave coupling effect even when the overlapping of phase space islands never occurs, and this nonlinear effect can lead to an energy flow between waves and modulate the energy exchange between waves and EPs. The background dissipation decreases the efficiency of energy exchange between EPs and waves further.
Perfect anomalous reflection and refraction with binary acoustic metasurfaces
Authors: Zhu Xing-Feng , Lau Siu-Kit
Published: December 2019

Binary acoustic metasurfaces (AMs) are proposed and demonstrated with the goal of perfect anomalous reflection and refraction. The AMs require only two subunits per period, thereby greatly improving the fabrication accuracy and reducing the design process. Theoretical analysis gives the range of incident and diffracted angles for the case of only two propagating modes, one of which can be suppressed by designing the two subunits to have opposite phases, thereby achieving perfect anomalous reflection/refraction. Moreover, the reflection- and refraction-type binary AMs are realized using two types of space-coiling structures. Finite-element simulations show the realization of anomalous reflection and refraction, the energy efficiencies of which can reach almost 100%. The present work provides a simple and straightforward way to design high-efficiency and practical AMs that enable nearly ideal manipulation of reflected/transmitted waves.
Inversion and reconstruction of supersonic cascade passage flow field based on a model comprising transposed network and residual network
Authors: Li Yunfei , Chang Juntao , Wang Ziao , Kong Cheng
Published: December 2019

A data-driven model comprising a transposed network and a residual network is proposed to predict the flow field structure of the supersonic cascade passage by measuring the wall pressure of the cascade passage. This model is based on the close relationship between the wall pressure values of the supersonic cascade passage and the flow field structure. Wind tunnel experiments of the supersonic cascade passage were conducted to obtain real experimental data. The transposed network, which is the first part of the model, consists of transposed convolution, normal convolution, and fully connected layers. However, the mapping ability of the transposed network between the wall pressure values and the cascade passage flow field structures was insufficient. The maximum relative error by the transposed network in predicting the position of the leading edge of the shock train was 8.5%. Therefore, the residual network was introduced as the second part of the model to achieve end-to-end super-resolution and improve the mapping ability of the model. After training, the residual network reduced the maximum relative error of the position prediction of the leading edge of the shock train to 3.5%. In the testing set, the prediction results of the model indicated that the movement of the leading edge of the shock train can be distinguished well. Furthermore, a combination of the two networks revealed the mapping relationship between the wall pressure of the supersonic cascade passage and the flow field structure. Thus, the results of this study lay a good foundation for the subsequent determination of the flow field stability margin.
Direct numerical simulation of a tip-leakage flow in a planar duct with a longitudinal slit
Authors: Fang Jian , Gao Yanfei , Liu Yangwei , Lu Lipeng , Yao Yufeng , Le Ribault Catherine
Published: December 2019

A planar duct flow configuration with a cross-flow injected from a longitudinal slit close to the upper wall of the duct is studied by using a direct numerical simulation approach to explore the underlying flow mechanism in relation to the tip-leakage vortex (TLV), which is one of the most important flow phenomena in turbomachinery. Major characteristics of TLV in a rotor of turbomachinery are identified in the current flow model. The analysis of mean and instantaneous flow fields reveals that the interaction between the main (axial) flow and jet (cross) flow is the primary source of the generation of the TLV. The evolution of the TLV is then investigated, and a vortex breakup phenomenon is identified. The evolution of TLV can be divided into three phases, i.e., the formation phase, the breakup phase, and the diffusion phase. Mean streamlines and turbulence kinetic energy (TKE) budgets are analyzed, showing that the high TKE central spot in the formation phase is due to the interaction between highly swirling vortex filaments and mean velocity gradient. In the outer part of the TLV, the TKE is mainly produced in the shear-layer and transported toward the center by the turbulence transport.
Photo-detecting of graphene/insulator/silicon heterojunction with direct tunneling mechanism
Authors: Yang Wenxin , Xu Ji , Zhai Yusheng , Shi Yutong , Zhang Xiaobing , Wang Qilong
Published: December 2019

Due to its atomically ultrathin morphology and superior optoelectronic properties, graphene has been broadly studied and utilized in phototransistors, photoconductors, or heterojunction nanostructures. However, in practical devices, the disadvantages of graphene should be concerned for its high dark current, very low on/off ratio, and high-priced fabrication cost. We report the photodetecting of the graphene/insulator/silicon heterojunction. The insulator layer is optimized to achieve balanced optoelectronic properties in terms of an Iph/Idark ratio of 4.17 × 103, a responsivity of 35 mA W−1, and a detectivity of 6.39 × 1010 Jones at a wavelength of 658 nm, with low operating voltage and static power dissipation (0.84 nW). Besides, response speed and degradation in the environment are tested. The mechanisms are revealed and analyzed by I-V measurements.
Sheath characteristics in a magnetically filtered low density low temperature multicomponent plasma with negative ions
Authors: Borgohain Binita , Bailung H.
Published: December 2019

Negative ion rich multicomponent plasma is produced in a novel plasma device for sheath studies. The experimental volume is composed of low electron temperature (Te∼0.2−0.4  eV) and low electron density (ne∼105−106 cm−3) argon (Ar) plasma with negative ions. Negative ions are introduced in the argon plasma by injecting sulfur hexafluoride (SF6) gas. Plasma parameters in the device are tunable, very close to the ionospheric plasma conditions specific to the D-region. A magnetic filter is used, which allows selective diffusion of low energy electrons and ions from a DC discharge source. Positive ion and electron/negative ion sheaths formed in front of a biased metal plate are investigated using an emissive probe. Both the positive ion and electron/negative ion sheaths are found to be of similar thickness and symmetric structure. With an enhanced negative ion concentration, the sheath thickness is found to decrease. Poisson's equation is derived considering the electrons as Maxwellian. The experimental results closely follow the prediction of Poisson's equation and the Debye sheath model. Sheath studies as shown here, for laboratory plasmas with near-ionospheric parameters, are important for the understanding of spacecraft-to-plasma interactions and for the design of ionospheric instrumentation.
First-principles magnetization relaxation equation of interacting ferrofluids with applications to magnetoviscous effects
Authors: Fang Angbo
Published: December 2019

Magnetization relaxation equation (MRE) plays a primary role in numerous phenomena and applications involving ferrofluid dynamics. However, as yet there exist no MREs derived from first principles and applicable to concentrated and strongly interacting ferrofluids. In this paper, we derive a novel MRE based on the projection operator technique. It sufficiently accounts for interparticle correlations beyond the scope of previous models. The MREs by Martsenyuk, Raikher, and Shliomis and by Zubarev and Yushkov (ZY), respectively, for ideal and weakly nonideal (WNI) ferrofluids, are recovered as low-order approximations. We also investigate the magnetoviscous effects. For the first time, we unveil qualitatively the different roles played by short- and long-range interparticle correlations. The long-range correlation effect dominates in a WNI ferrofluid, and both our MRE and the ZY model are in quantitative agreement with simulations on field-dependent rotational viscosity. However, for strongly nonideal ferrofluids, short-range correlations can become substantial and compete with long-range correlations to reduce rotational viscosities. Our MRE is the first dynamic model faithfully capturing both short- and long-range correlations, thereby applicable to ferrofluids characterized by a broad range of concentrations and interacting strengths. It is expected to be a cornerstone for quantitative modeling of the dynamic response of ferrofluids to external fields or flow deformations. Because most commercial ferrofluids are designed to be strongly nonideal to enhance magnetic response, our theory may provide fresh insights for applications of realistic ferrofluids in industry and biomedicine.
Continuously variable diffraction gratings using electroconvection in liquid crystals for beam steering applications
Authors: Morris R. , Jones J. C. , Nagaraj M.
Published: December 2019

There is a great technological need for the development of devices capable of producing wide-angle and efficient, transmissive optical beam steering. In this article, variable pitch phase diffraction gratings using electroconvection in liquid crystals are considered for applications in electrically controllable beam-steerers. The devices contain thin layers of nematic liquid crystal mixtures of negative dielectric anisotropy, which are doped with different concentrations of an ionic species to determine the effect of conductivity on the beam-steering characteristics. The devices are seen to act as continuously variable diffraction gratings, where the pitch increases with the frequency of the applied electric field. The second order diffraction peak is found to be the most efficient, with absolute efficiency ranging from 5% to 15%, and continuous steering from 4° to 8° within 20 μm spaced devices. Devices with thinner layers of liquid crystal were also examined; these demonstrated wider angle steering but had substantial losses of efficiency due to lowering of optical contrast. Suggestions for possible methodologies for optimizing such devices are discussed.
Two-liquid electroosmotic thrusters for micro propulsion applications
Authors: Huang Kun-Hao , Huang Hsin-Fu
Published: December 2019

We investigate analytically the thruster performances and power consumption rates of a two-liquid electroosmotic thruster based on slit microchannels with hydrodynamic slip walls. The two electrolytes are considered to have different material properties and are arranged in the configuration of a core liquid layer surrounded by immiscible outer liquid layers with the outer layers in contact with the microchannel solid walls, thus forming electrical double layers at the solid-liquid interface. Interfacial potential jumps and surface charge densities are included to model the liquid-liquid interfacial double layers. Results reveal that, with the properties of both liquids being identical, nonzero liquid-liquid interfacial electrostatics only slightly increase the thrust but noticeably reduce the thruster efficiency and thrust-to-power ratio due to the enhanced Joule heating and viscous dissipation caused by the increased charge distributions and distorted velocity profiles. Moreover, the thrust and efficiency can be substantially increased as the dynamic viscosity ratio is decreased with the density ratio fixed at one, whereas the thrust, efficiency, and thrust-to-power ratio are all significantly enhanced by increasing the dynamic viscosity ratio when the kinematic viscosity ratio equals to one. The bulk electrolyte concentration/conductivity ratio is identified as a key parameter capable of simultaneously maximizing one or more thruster performances. While improving upon the performances of the single-liquid electroosmotic thruster previously reported, the two-liquid results and modeling presented herein may likely relax the limitations on the choice of electroosmotic propellants, increase the operational flexibility of electrokinetic thrusters, and be further applied in space or underwater micropropulsion applications.
Programming patchy particles to form complex periodic structures
Authors: Tracey Daniel F. , Noya Eva G. , Doye Jonathan P. K.
Published: December 2019

We introduce a scheme to design patchy particles so that a given target crystal is the global free-energy minimum at sufficiently low temperature. A key feature is a torsional component to the potential that only allows binding when particles have the correct relative orientations. In all examples studied, the target crystal structures readily assembled on annealing from a low-density fluid phase, albeit with the simpler target structures assembling more rapidly. The most complex example was a clathrate with 46 particles in its primitive unit cell. We also explored whether the structural information encoded in the particle interactions could be further reduced. For example, removing the torsional restrictions led to the assembly of an alternative crystal structure for the BC8-forming design, but the more complex clathrate design was still able to assemble because of the greater remaining specificity.
Fluid and kinetic nonlinearities of near-acoustic plasma waves
Authors: Affolter M. , Anderegg F. , Dubin D. H. E. , Valentini F. , Driscoll C. F.
Published: December 2019

Large amplitude, near-acoustic plasma waves have a temperature-dependent harmonic content and nonlinear frequency shifts. On cold plasmas, experiments show that fluid nonlinearities dominate, and the observed harmonic content is well predicted by a recent fluid analysis. In contrast, the measured nonlinear frequency shift is smaller than this theory prediction, suggesting the presence of other nonlinear effects neglected in this analysis. When the plasma is heated, kinetic effects become important, and we observe an increase in both the harmonic content and nonlinear frequency shift. Quantitative experiments on the stability of these large amplitude, near-acoustic plasma waves strongly support the idea that trapped particles reduce the amplitude threshold for instability below fluid models. At low temperatures, the broad characteristics of the parametric instability are determined by the frequency detuning of the pump and daughter wave and the wave-wave coupling strength, surprisingly consistent with simple cold fluid, three-wave theories. However, at higher temperatures, the pump wave becomes unstable at half the threshold pump wave amplitude, with similar exponential growth rates as for a cold plasma.
Effect of electron collisions on stationary solutions of plasma diodes in the case with electron reflection
Authors: Kuznetsov V. I. , Gerasimenko A. B. , Pramanik S. , Chakrabarti N.
Published: December 2019

The stationary states of the Pierce diode are found in the presence of reflection of electrons from the potential barrier when electron scattering by background particles is taken into account. Solutions are divided into two groups: Bursian and non-Bursian. It is shown that non-Bursian solutions disappear when the average collision frequency is of the order of 10% of the plasma frequency. The results can be used to optimize the characteristics of a thermionic energy converter operating in the regime with surface ionization.
The spin-forbidden vacuum-ultraviolet absorption spectrum of 14N15N
Authors: Heays A. N. , Lewis B. R. , de Oliveira N. , Ubachs W.
Published: December 2019

Photoabsorption spectra of 14N15N were recorded at high resolution with a vacuum-ultraviolet Fourier-transform spectrometer fed by synchrotron radiation in the range of 81–100 nm. The combination of high column density (3 × 1017 cm−2) and low temperature (98 K) allowed for the recording of weak spin-forbidden absorption bands’ exciting levels of triplet character. The triplet states borrow intensity from 1Πu states of Rydberg and valence character while causing their predissociation. New predissociation linewidths and molecular constants are obtained for the states C3Πu(v = 7, 8, 14, 15, 16, 21), G3Πu(v = 0, 1, 4), and F3Πu(v = 0). The positions and widths of these levels are shown to be well-predicted by a coupled-Schrödinger equation model with empirical parameters based on experimental data on 14N2 and 15N2 triplet levels.
Unbiasing the initiator approximation in full configuration interaction quantum Monte Carlo
Authors: Ghanem Khaldoon , Lozovoi Alexander Y. , Alavi Ali
Published: December 2019

We identify and rectify a crucial source of bias in the initiator full configuration interaction quantum Monte Carlo algorithm. Noninitiator determinants (i.e., determinants whose population is below the initiator threshold) are subject to a systematic undersampling bias, which in large systems leads to a bias in the energy when an insufficient number of walkers are used. We show that the acceptance probability (pacc), that a noninitiator determinant has its spawns accepted, can be used to unbias the initiator bias, in a simple and accurate manner, by reducing the applied shift to the noninitiator proportionately to pacc. This modification preserves the property that in the large walker limit, when pacc → 1, the unbiasing procedure disappears, and the initiator approximation becomes exact. We demonstrate that this algorithm shows rapid convergence to the FCI limit with respect to the walker number and, furthermore, largely removes the dependence of the algorithm on the initiator threshold, enabling highly accurate results to be obtained even with large values of the threshold. This is exemplified in the case of butadiene/ANO-L-pVDZ and benzene/cc-pVDZ, correlating 22 and 30 electrons in 82 and 108 orbitals, respectively. In butadiene 5 × 107 and in benzene 108 walkers suffice to obtain an energy within a millihartree of the coupled cluster singles doubles triples and perturbative quadruples [CCSDT(Q)] result in Hilbert spaces of 1026 and 1035, respectively. Essentially converged results require ∼108 walkers for butadiene and ∼109 walkers for benzene and lie slightly lower than CCSDT(Q). Owing to large-scale parallelizability, these calculations can be executed in a matter of hours on a few hundred processors. The present method largely solves the initiator-bias problems that the initiator method suffered from when applied to medium-sized molecules.
Methane emission, ruminal fermentation parameters and fatty acid profile of meat in Santa Inês lambs fed the legume macrotiloma
Authors: Lima Paulo de Mello Tavares , Filho Adibe Luiz Abdalla , Issakowicz Juliano , Ieda Egon Hion , Corrêa Patrícia Spoto , de Mattos Waldssimiler Teixeira , Gerdes Luciana , McManus Concepta , Abdalla Adibe Luiz , Louvandini Helder
Published: December 2019

Context Using legumes in ruminant production system may provide benefits such as improvement in animal performance and decrease in methane (CH4) emissions, mainly based on nutritional characteristics of these plants and the presence of tannins. Macrotiloma (Macrotyloma axillare) is a tropical legume that still lacks studies regarding its effects on animal performance and CH4 emissions. Aims The objective of this experiment was to evaluate productive performance, CH4 emission, ruminal fermentation parameters, carcass characteristics and fatty acid profile of the meat from lambs fed tropical grass hay supplemented with the legume forage macrotiloma. Methods For a 90-day experimental period, 14 Santa Inês male lambs (aging 100 days; 18.06 ± 3.26 kg initial bodyweight) were allocated in individual pens and divided into two treatments: chopped aruana grass (Panicum maximum cv. Aruana) hay (CON); aruana hay supplemented with chopped macrotiloma hay at a ratio of 75:25 grass to legume (MAC). Lambs were weighed fortnightly for calculation of average daily bodyweight gain (ADG) and CH4 emission was measured on three occasions (days 28 to 32; 57 to 61; 85 to 89) using the sulfur hexafluoride (SF6) tracer technique. At the last day of CH4 collection, rumen fluid samples were collected for: determination of ammoniacal nitrogen (NH3-N) and short chain fatty acids (SCFA); ruminal protozoa count; and relative abundance determination of general bacteria (BACT); Ruminococcus flavefaciens (RUMI); Fibrobacter succinogenes (FIBRO); methanogenic archaea (METH) by real-time quantitative PCR (real-time-qPCR) analysis. Subsequently, after 16 h fasting, the animals were slaughtered; carcass characteristics were then evaluated and longissimus thoracis samples were collected for fatty acid profile analysis. Key results No significant difference (P > 0.05) was observed between MAC and CON for productive performance, CH4 emission, SCFA and carcass characteristics. Reduced protozoa count and relative abundance of METH were observed for MAC (P < 0.05). Conclusions Despite the lack of effects on productive performance and CH4 emission, the decreased relative abundance of METH and protozoa count indicated that macrotiloma may possibly present anti-methanogenic activity. Implications The inclusion of this legume in the diet of ruminants may affect rumen microbes and potentially decrease environmental impacts of the production system.
Descriptions of spawning of the pouched lamprey (Geotria australis) in tanks and of morphological changes leading up to and following spawning
Authors: Paton K. R. , Cake M. H. , Bird D. J. , Potter I. C.
Published: December 2019

The anadromous Geotria australis, one of only three lamprey species representing the early agnathan (jawless) stage of vertebrate evolution in Australia and New Zealand, is declining in abundance. Its adults were caught soon after they had entered rivers on their non-trophic upstream migration and maintained in laboratory tanks for 13–15 months through to spawning. As adult G. australis are susceptible to haemorrhagic septicaemia, they were treated prophylactically and maintained in 3-m3 aquaria supplied with a flow-through charcoal filtration system and UV steriliser. Air temperature and the light:dark regime were constantly adjusted to parallel those in the environment. Males developed the very large suctorial disc and gular pouch characteristic of maturity and both sexes matured at the same time as in the wild. While males frequently showed aggressive behaviour towards each other, the same male and female mated on several occasions. The male coiled around the female and, with his urogenital papilla close to the female’s cloaca, twisted and vibrated, leading to egg release. These eggs formed coagulated clusters as in the wild, with many progressing through to the eight-cell stage. Remarkably, numerous G. australis were still alive 95–392 days after the end of the short spawning period, and one male after a further 119 days. Postspawning survival would be facilitated inter alia by extensive proteolysis, reflected in a shortening of the body. The data in this paper emphasise that G. australis is a highly atypical lamprey and provides invaluable information for conserving this declining species.
Within‐sport specialisation and entry age as predictors of success among age group swimmers
Authors: Staub Ilka , Zinner Christoph , Bieder Andreas , Vogt Tobias
Published: December 2019

Early specialisation versus early diversification in long‐term athlete development remains controversial. Although several parameters of sport specialisation have already been explored, this study investigates within‐sport specialisation in the careers of young swimmers. In this cohort study, the number of strokes, events and distance categories during childhood and adolescence, as well as entry age were analysed to find potential correlations with success at age 18. Also, national team members were compared to non‐members within this cohort. The number of events, strokes or distance categories at a younger age showed a moderate correlation to the best FINA point score at the age of 18, i.e. the greater the diversification, the greater the performance at age 18. The number of events, strokes or distance categories however, showed a stronger correlation when comparing national team members with the non‐members. Most of the observed athletes were more likely to have high FINA points at 18 if they had been listed in the top 100 at 11 years of age. Entry age had a strong negative correlation with the FINA point score at 18, i.e. the younger the athlete when entering the top 100, the higher the FINA point score at 18. When national team members were compared to non‐national team members, early age of entry into the top 100 showed a greater impact on the national team members. However, being listed in more than one stroke as a child correlates well with success at age 18.
Rotating clouds of charged Vlasov matter in general relativity
Authors: Thaller Maximilian
Published: December 2019

The existence of stationary solutions of the Einstein–Vlasov–Maxwell system which are axially symmetric but not spherically symmetric is proven by means of the implicit function theorem on Banach spaces. The proof relies on the methods of Andréasson et al (2014 Commun. Math. Phys. 329 787–808) where a similar result is obtained for uncharged particles. Among the solutions constructed in this article there are rotating and non-rotating ones. Static solutions exhibit an electric but no magnetic field. In the case of rotating solutions, in addition to the electric field, a purely poloidal magnetic field is induced by the particle current. The existence of toroidal components of the magnetic field turns out to be not possible in this setting.
Inverse problems with partial data for elliptic operators on unbounded Lipschitz domains
Authors: Behrndt Jussi , Rohleder Jonathan
Published: December 2019

For a second order formally symmetric elliptic differential expression we show that the knowledge of the Dirichlet-to-Neumann map or Robin-to-Dirichlet map for suitably many energies on an arbitrarily small open subset of the boundary determines the self-adjoint operator with a Dirichlet boundary condition or with a (possibly non-self-adjoint) Robin boundary condition uniquely up to unitary equivalence. These results hold for general Lipschitz domains, which can be unbounded and may have a non-compact boundary, and under weak regularity assumptions on the coefficients of the differential expression.
Ionization of biological molecules by multicharged ions using the stoichiometric model
Authors: Mendez A M P , Montanari C C , Miraglia J E
Published: December 2019

In the present work, we investigate the ionization of molecules of biological interest by the impact of multicharged ions in the intermediate to high energy range. We performed full non-perturbative distorted-wave calculations (CDW) for thirty-six collisional systems composed by six atomic targets: H, C, N, O, F, and S—which are the constituents of most of the DNA and biological molecules—and six charged projectiles (antiprotons, H, He, B, C, and O). On account of the radiation damage caused by secondary electrons, we inspect the energy and angular distributions of the emitted electrons from the atomic targets. We examine seventeen molecules: DNA and RNA bases, DNA backbone, pyrimidines, tetrahydrofuran (THF), and C
n
H
n
compounds. We show that the simple stoichiometric model (SSM), which approximates the molecular ionization cross sections as a linear combination of the atomic ones, gives reasonably good results for complex molecules. We also inspect the extensively used Toburen scaling of the total ionization cross sections of molecules with the number of weakly bound electrons. Based on the atomic CDW results, we propose new active electron numbers, which leads to a better universal scaling for all the targets and ions studied here in the intermediate to the high energy region. The new scaling describes well the available experimental data for proton impact, including small molecules. We perform full molecular calculations for five nucleobases and test a modified stoichiometric formula based on the Mulliken charge of the composite atoms. The difference introduced by the new stoichiometric formula is less than 3%, which indicates the reliability of the SSM to deal with this type of molecules. The results of the extensive ion-target examination included in the present study allow us to assert that the SSM and the CDW-based scaling will be useful tools in this area.
A drift-diffusion simulation model for organic field effect transistors: on the importance of the Gaussian density of states and traps
Authors: Darwish Mohammed , Gagliardi Alessio
Published: December 2019

The nature of charge transport in organic materials depends on several important aspects, such as the description of the density of states, and the charge mobility model. Therefore specific models describing electronic properties of organic semiconductors must be considered. We have used an organic based drift-diffusion model for the electrical characterization of organic field effect transistors (OFETs) utilizing either small molecules or polymers. Furthermore, the effect of interface traps, bulk traps, and fixed charges on transistor characteristics are included and investigated. Finally, simulation results are compared to experimental measurements, and conclusions are drawn out in terms of transistor performance parameters including threshold voltages, and field-dependent mobilities.
Crossover from weak-antilocalization transport to quantum magnetoresistance of Dirac states in quenched Fe0.01Bi2Te3 single crystals with large magnetoresistance and high Hall mobility
Authors: Wang Li-Min , Wang Shuo-Hong , Shen Dong , Yang Tien-Wei , Chen I-Nan
Published: December 2019

Magnetotransport properties with a large positive magnetoresistance (MR) and a high carrier mobility for applications have been achieved and probed for quenched Fe0.01Bi2Te3 single crystals. Large positive MR of ∼470% with a Hall mobility of ∼44 000 cm2 V−1 s−1 at 5 K and 6 T has been observed on a quenched Fe0.01Bi2Te3 sample, in which the electrical parameters can be tuned by the quenching temperature T

q
. The MR behaviors for the quenched samples show a crossover from a weak antilocalization-dominant MR to a linear and non-saturating MR at temperatures of T* ≈ 58−100 K, where the large MR at low temperatures possibly originates from the mechanism of topologically protected backscattering. On the contrary, the MR behaviors for the strain-released sample do not show such a distinct crossover, where only linear-like and non-saturating MR behaviors can be observed. Different electrical transports between the quenched and strain-released samples indicate that the band structure, as well as the surface Dirac electrons in Fe0.01Bi2Te3, can be modified by the lattice strain. Furthermore, it is found that the low-temperature magnetoconductivity can be well described by the weak-antilocalization transport formula, while the high-field linear-like MR at T > T* can be explained in terms of Abrikosov’s quantum transport of Dirac-cone states in quenched Fe0.01Bi2Te3 single crystals.
Quantum illumination assistant with error-correcting codes
Authors: Zhang Wen-Zhao , Ma Yu-Han , Chen Jing-Fu , Sun Chang-Pu
Published: December 2019

We scheme how to enhance the detection ability of quantum target recognition without using entanglement resources. Based on the commonly used error-correcting codes and corresponding decoding method, our scheme gives lower error probability and higher signal-to-noise ratio (SNR) in comparison with the conventional entanglement protocols. In addition, we further investigate the interplay between the SNR and the detection efficiency in quantum target recognition. Results show that, they behave a completely reverse trend when increasing the auxiliary dimension. This is an important limiting factor when optimizing the detection process. Under the existing experimental conditions, our protocol has stronger ability to resist environmental noise when keeping a certain SNR and detection efficiency. Our scheme provides a potential platform for further research and implementation of quantum target recognition.
Ion generation and loading of a Penning trap using pulsed laser ablation
Authors: Sameed Muhammed , Maxwell Daniel , Madsen Niels
Published: December 2019

We investigated the production of aluminum and beryllium ions via pulsed laser ablation using 355 nm wavelength and 5 ns long laser pulses. The ablation threshold of Al+ and Be+ was measured to be 0.9 ± 0.1 (stat.) ± 0.3 (syst.) J cm−2 and 1.4 ± 0.1 (stat.) ± 0.4 (syst.) J cm−2 respectively. By employing electrostatic retarding potentials, the kinetic energy profile of the ablated ions was characterized as a function of laser fluence. Around the ablation threshold, we reliably produced between 108 and 1010 ions, approximately 5% of which were dynamically trapped in a Penning–Malmberg trap.
Asking Neutrons where they have been
Authors: Sponar St. , Geppert H. , Denkmayr T. , Lemmel H. , Hasegawa Y.
Published: December 2019

Based on the results of Vaidman’s photonic three-path interferometer experiment with weak path marking [A. Danan, D. Farfurnik, S. Bar-Ad, and L. Vaidman, Phys. Rev. Lett. 111, 240402 (2013)] the authors claim that the photons have discontinuous particle trajectories. Here, we present a neutron optical version of the experiment by Danan et al., where in various beam paths of the interferometer the energy of the neutrons is slightly shifted. This is achieved by using resonance-frequency spin-rotators (SR) operating at different frequencies. The which-way information is derived from the time-dependent intensity, which is considered to result from the interfering cross terms between the stationary main component and the energy-shifted which-way signals. Our statements are based on a simple theoretical model, following the time evolution of the wave function of the neutrons, which clarifies the observation in the framework of standard quantum mechanics and reveals the multifold presence of the neutron’s wave function in the interferometer.
Polarization analysis on the LET cold neutron spectrometer using a 3He spin-filter: first results
Authors: Cassella G , Stewart J R , Paternò G M , García Sakai V , Devonport M , Galsworthy P J , Bewley R I , Voneshen D J , Raspino D , Nilsen G J
Published: December 2019

We report on the design and construction of a neutron polarization analyzer based on a 3He spin filter for the LET spectrometer at the ISIS facility. Its commissioning completes the uniaxial polarized mode of the instrument. Besides the 3He spin filter cell, the analyzer consists of a set of electromagnetic coils to provide a uniform magnetic field, and a collimator to eliminate background from the sample environment and analyzer infrastructure. The 3He cell is separated from the LET main tank vacuum by means of a gas tank, which permits rapid cell changeovers and guarantees safe operation. In addition to the analyzer hardware, software has been written to reduce and correct polarized data. The successful operation of the polarized mode was realized for the separation of coherent and incoherent dynamics in an organic solar cell polymer blend.
in-situ 3He SEOP polarizer for Thermal neutrons
Authors: Salhi Zahir , Babcock Earl , Bingöl Kendal , Bussmann Klaus , Kammerling Hans , Ossovyi Vladimir , Heynen Achim , Deng Hao , Hutanu Vladimir , Masalovich Sergey , Voigt Jörg , Ioffe Alexander
Published: December 2019

In this article, we describe a neutron polarizer for a new time-of-flight neutron spectrometer with the polarization analysis TOPAS. This instrument will use the convergent focused incoming beam of thermal neutrons with energies up to 150 meV (wavelength down to 0.74Å). The polarizer employs a high opacity 3He neutron spin filter with continuous 3He polarization provided by two laser array bars frequency narrowed by an ultra-compact volume Bragg grating. The system was successfully prototyped, and tested. In the course of first experimental test at the polarized hot neutron diffractometer POLI at MLZ, neutron polarization of 97.6% was achieved for 0.895Å neutrons and kept constant during 30 days.
Applying Resonant Spin Flippers with Poleshoes and Longitudinal Radio Frequency Fields to Time of Flight MIEZE
Authors: Geerits N. , Parnell S.R. , Thijs M.A. , Bouwman W.G. , Plomp J.
Published: December 2019

A time of flight MIEZE spectrometer study is presented. The instrument uses solenoid radio frequency (RF) spin flippers with square pole shoes and a magnetic yoke. These flippers can achieve higher static fields than conventional resonant RF spin flippers, which employ an air core. High fields are crucial for the construction of a high resolution and compact MIEZE spectrometer. Using both types of flippers two MIEZE spectrometer configurations are constructed and compared on the same beam line. It was demonstrated that the pole shoe/solenoid coil RF flippers can achieve a MIEZE signal, which is similar in quality to the conventional reference setup. The highest obtained modulation frequency was 100 kHz.
Experimental test of 3He neutron-spin filter in MIEZE spectrometer
Authors: Hayashida H , Hino M , Endo H , Oku T , Okudaira T , Sakai K , Oda T
Published: December 2019

A modulated intensity by zero effort (MIEZE) spectrometer is a type of neutron-resonance spin-echo spectrometer and can be used to analyze the slow dynamics of condensed matter by measuring the intermediate scattering function I(Q,τ). A crucial feature of a MIEZE spectrometer is it leaves completely free the space between the sample and the detector because the sample is placed after the neutron-spin analyzer. Measuring the magnetic dynamics with a conventional neutron-spin-echo spectrometer is difficult, but with a MIEZE spectrometer such a measurement may be done simply by introducing a second analyzer after the sample. Measuring the magnetic dynamics with high precision requires the background to be reduced to a minimum and is a job for which a 3He neutron-spin filter (3He-NSF) is a promising candidate as a second analyzer. However, one difficulty with this approach is the diffusion of 3He gas from the 3He-NSF, which may be measured and interpreted as dynamics. Therefore, we investigate herein whether the dynamics of gas diffusion is detected when using a 3He-NSF as second analyzer in a MIEZE spectrometer. Toward this end, we experimented with the MIEZE spectrometer installed at beamline 06 (BL06) at the Materials and Life Science Experimental Facility at Japan Proton Accelerator Research Complex (J-PARC MLF). The results confirm that the gas-diffusion dynamics of the 3He-NSF are not detected, and that the 3He-NSF, therefore, can be used as a second analyzer in this MIEZE spectrometer.
Developing Wide Angle Spherical Neutron Polarimetry at Oak Ridge National Laboratory
Authors: Wang T. , Silva N. , Jiang C. Y. , Agrawal H. K. , Li F. , Debeer-Schmitt L. , Masaaki M. , Ruff J. , Pynn R. , Tong X. , Winn B.
Published: December 2019

The Spherical Neutron Polarimetry (SNP) Technique probes complex magnetic structures which are inaccessible by other methods. This technique is achieved by combining a zero-field sample chamber with full control of incoming and outgoing neutron polarization. While wide-angle SNP capability has been fully implemented in Europe, it is still in development in the US. At Oak Ridge National Laboratory, we are developing a wide-angle SNP capability suited for multiple neutron beamlines. The design is based on the basic concept of SNP while utilizing high-Tc superconducting films and Mu-metal. In this article we report our recent development of the SNP capability and its future applications.
Total interference between nuclear and magnetovibrational one-phonon scattering cross sections
Authors: Raymond S. , Biniskos N. , Schmalzl K. , Persson J. , Brückel T.
Published: December 2019

A full phonon intensity cancellation is reported in a longitudinal polarized inelastic neutron scattering experiment performed on the magnetocaloric compound MnFe4Si3, a ferromagnet with TCurie
≈ 305 K. The TA[100] phonon polarized along the c-axis measured from the Brillouin zone center G=(0, 0, 2) is observed only in one (

σ

z

+
+

) of the two non-spin-flip polarization channels and is absent in the other one (

σ

z

−
−

) at low temperatures. This effect disappears at higher temperatures, in the vicinity of TCurie
, where the phonon is measured in both channels with nonetheless marked different intensities. The effect is understood as originating from nuclear-magnetic interference between the nuclear one-phonon and the magnetovibrational one-phonon scattering cross-sections. The total cancellation reported is accidental, i.e. does not correspond to a systematic effect, as established by measurements in different Brillouin zones.
Wave properties using displaced phase amplitude
Authors: Fadhiliani D , Ramli M , Rizal S , Munzir S , Syafwan M
Published: December 2019

Displaced phase-amplitude variable in polar form. This variable is used to investigate changes in amplitude in complex fields with phases that depend only on the position in the propagation. Soliton on Finite Background (SFB) which is an exact solution of Nonlinear Schrodinger (NLS) equation has been widely used in investigating wave propagation dynamics so that it is the basic for the proposed displaced phase-amplitude. Using displaced phase-amplitude, the results obtained can be described in Argand Diagrams. Wave equation used as a model is the Benjamin Bona Mahony (BBM) equation where the envelope of this wave evolves following the NLS equation. This wave is unidirectional long wave on the surface and has low amplitude characteristics. Step by step to obtain a SFB solution that contains displaced phase-amplitude described and displayed in an argand diagram. In additional, the envelope graph is given.
Chemical and sensory analysis of several sweet potatoes (Ipomoea batatas L.) clones
Authors: Hayati M , Sabaruddin  , Efendi  , Anhar A
Published: December 2019

This study aims to find out suitable chemical composition and sensory test of 24 sweet potato clones to select clones that meet consumer preferences. This study was conducted at the Laboratory of Animal Food, Faculty of Agriculture, Universitas Syiah Kuala in September to October, 2015. The clones used in this study were nineteen sweet potato clones passed by CIP-SEA Bogor, Indonesia, and five Local clones. The study used Completely Randomized Design of non-factorial where clones were treated. The highest moisture content and ash were found in Cream Saree, local clones (83%; 4.77%). The highest protein content was found in CIP-BDG and CIP-WHI5 clones (4.89%; 4.58%), and the highest carbohydrate content (56.10%) was found in CIP-CER. The sensory results were that the preferred round tuber shape was found on CIP-513 clone, the preferred texture of tuber skin and soft tuber flesh were found on CIP-MAN, CIP-BDG, CIP-WHI5, CIP-204, CIP-B19, CIP-287, CIP-GA, SARI, local Cream Saree, local Orange Saree, the preferred skin color and purple tuber flesh were found in CIP-1945 clones, CIP-BDG, and CIP-W, the preferred sweet tuber taste was found in CIP-B9 clones, and the overall reception criteria was found on the CIP-GA clone.
Forefront of liquid metal technologies for fusion reactors
Authors: Kondo Masatoshi
Published: December 2019

Fusion reactor is an innovative power plant, which is necessary for a sustainable society. The important issue is the development of key components, i.e. tritium breeding blanket and divertor. Liquid metal Li and Pb-16Li are candidate tritium breeders, which also function as a reactor coolant. Liquid Sn is a promising coolant of liquid surface divertor, which is responsible for power exhaust and impurity removal through guided plasma exhaust in magnetic plasma confinement fusion reactors. The design studies on the liquid breeder blanket and the liquid surface divertor are being conducted toward fusion DEMO reactor. The chemical behaviours of liquid metals have been studied to improve the tritium transfer and the material compatibility. This paper reviews recent studies on the liquid metal technologies for the fusion reactors.