bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lock-in technique for precise measurement of ion distribution functions
Authors: Lütke Stetzkamp Christian , Tsankov Tsanko Vaskov , Czarnetzki Uwe 
Published: April 2021

Abstract
Retarding field energy analyzers are commonly used for the experimental determination of the distribution of ions. Measurements require taking the first derivative of the measured current with respect to the retarding voltage, which limits the accuracy of the results. Here a commercial energy analyzer is combined with a lock-in detection and AC modulation technique to obtain ion distribution functions with an improved dynamic range. The technical realization of the method together with its theoretical motivation are presented. The various challenges for implementing the technique and ways to address them are given. The energy resolution of the method is discussed based on the concept of transfer functions, and the influence of the various adjustable parameters (grid bias voltages, frequency and amplitude of the modulation signal) on the obtained results are studied. The application of the method to an inductive discharge readily shows a dynamic range of more than three orders of magnitude. This dynamic range provides information on additional plasma parameters, such as the potential and the plasma density at the sheath edge and in the center of the discharge. Possibilities for further improvement of the technique are discussed.
Frustration in block copolymer assemblies
Authors: Shi An-Chang 
Published: April 2021

Abstract
Frustration is ubiquitous in condensed matter systems and it provides a central concept to understand the self-assembly of soft matter. Frustration is found at multiple scales in polymeric systems containing block copolymers. At the molecular scale, frustration arises because the chemically distinct blocks repel each other whereas the chain connectivity prevents a macroscopic separation. At the mesoscopic scale, frustration occurs due to the competition between the tendency for the block copolymer assemblies to maintain their native shape and the requirement to fill the space. At an even larger scale, frustrations could be induced by external fields or spatial confinement. Recent theoretical and experimental studies provide a good understanding of the origin of various frustrations in the self-assembly of block copolymers. Furthermore, it has been demonstrated that designed block copolymer systems, either in the form of multiblock copolymers with different architectures or block copolymer blends, could be utilized to regulate frustrations resulting in the formation of complex ordered and hierarchically structured phases.
A new phantom developed to test the ATCM performance of chest CT scanners
Authors: Yang Yang , Zhuo Weihai , Chen Bo , Lu Shunqi , Zhou Pei , Ren Wenliang , Liu Haikuan 
Published: April 2021

Abstract
In this study, a new ATCM phantom was developed to test the performance of the automatic tube current modulation (ATCM) of computed tomography (CT) scanners.. Based on the Chinese reference man and Monte Carlo simulations of x-ray attenuation, a more realistic ATCM phantom made of polymethyl methacrylate was developed. The phantom has a length of 20 cm, and it can be used to measure the dose profile along the central axis using 19 real-time MOSFET detectors. The image noise can be calculated slice by slice in the phantom’s center. Test experiments showed that the phantom could initiate tube current modulation under different modulation levels of CT scans, and the actual effects of ATCM could be evaluated with the aid of the dose profile measurements. Using the measured dose profiles and image noise, the preferred dose can easily be identified from a choice of different modulation levels. The new phantom developed in this study can be used to test the ATCM performance of CT scanners, and is useful for further studies of the optimization of CT scan protocols with ATCM.
Surface-confinement assisted synthesis of nitrogen-rich single atom Fe−N/C electrocatalyst with dual nitrogen sources for enhanced oxygen reduction reaction
Authors: Cui Yaqi , Xu Jiaoxing , Zhao Yi , Guan Lunhui 
Published: April 2021

Abstract
The utilization of earth abundant iron and nitrogen doped carbon as a precious-metal-free electrocatalyst for oxygen reduction reaction (ORR) significantly depends on the rational design and construction of desired Fe−N
x
moieties on carbon substrates, which however remains an enormous challenge. Herein a typical nanoporous nitrogen-rich single atom Fe−N/C electrocatalyst on carbon nanotube (NR-CNT@FeN-PC) was successfully prepared by using CNT as carbon substrate, polyaniline (PANI) and dicyandiamine (DCD) as binary nitrogen sources and silica-confinement-assisted pyrolysis, which not only facilitate rich N-doping for the inhibition of the Fe agglomeration and the formation of single atom Fe−N
x
sites in carbon matrix, but also generate more micropores for enlarging BET specific surface area (up to 1500 m2·g−1). Benefiting from the advanced composition, nanoporous structure and surface hydrophilicity to guarantee the sufficient accessible active sites for ORR, the NR-CNT@FeN-PC catalyst under optimized conditions delivers prominent ORR performance with a half-wave potential (0.88 V versus RHE) surpass commercial Pt/C catalyst by 20 mV in alkaline electrolyte. When assembled in a home-made Zn−air battery device as cathodic catalyst, it achieved a maximum output power density of 246 mW·cm−2 and a specific capacity of 719 mA·h·g−1
Zn outperformed commercial Pt/C catalyst, holding encouraging promise for the application in metal-air batteries.
Targeted antitumor comparison study between dopamine self-polymerization and traditional synthesis for nanoparticle surface modification in drug delivery
Authors: Zhang Mengying , Zou Yuan , Zuo Cuiling , Ao Hui , Guo Yifei , Wang Xiangtao , Han Meihua 
Published: April 2021

Abstract
To improve the therapeutic efficacy of anticancer agents and extend their application, mussel-inspired chemical modifications have attracted considerable attention. Surface modification based on polydopamine (PDA) has been a facile and versatile method to immobilize biomolecules on substrates for targeted drug delivery. To better analyze pharmaceutical differences between PDA-based surface modification and traditional synthesis methods, we prepared two kinds of folate (FA)-targeted nanoparticles (NPs) loaded with paclitaxel (PTX). The resultant PTX-PDA-FA NPs and PTX-FA NPs represented PDA and synthesis strategies, respectively. PTX-PDA-FA NPs and PTX-FA NPs have been characterized. The particle size of PTX-PDA-FA NPs was smaller than that of PTX-FA NPs. The two kinds of NPs both exhibited long-rod morphology, good colloidal stability and sustained slow drug release. Cytotoxicity in vitro was evaluated, and antitumor efficacy was investigated against 4T1 tumor-bearing mice. The tumor targeting therapeutic index of PTX-PDA-FA NPs and PTX-FA NPs showed equivalent superior specificity compared to nontargeted groups, which indicated that FA successfully attached to the surface of NPs by the PDA method and that the antitumor effect was equivalent to that of FA-modified NPs prepared by the chemical synthesis method. These results further indicated that PDA, as a simple and effective chemical surface modification platform, could be developed and applied in targeted delivery systems.
Effect of carbon nano tube in the structural and physical properties of polyvinyl chloride films
Authors: Helal A I , Vshivkov S A , Zaki M F , Elkalashy Sh I , Soliman T S 
Published: April 2021

Abstract
Polyvinyl chloride (PVC) films loaded by different concentration of Carbon Nano Tubes (CNT) are prepared through a solution casting method. CNT are characterized using transmission electron microscope (TEM) and x-ray diffractometer (XRD). The analysis of the PVC-CNT films is carried out by using XRD, scanning electron microscope (SEM), and Fourier transform infrared (FTIR) to study the change in the polymer structure. UV–vis spectrophotometer is used to determine the optical parameters depending on the optical absorption data. It is found that, the direct and indirect optical band gap decrease with an increase in CNT nanoparticle content in the PVC matrix. The refractive index, optical dielectric parameters, and optical conductivity of the polymer films are investigated using the optical absorption data. These parameters are enhanced with the increase in the CNT concentration in the PVC matrix. The Wemple-DiDomenico model is used to calculate the optical dispersion parameters (like; oscillator energy, dispersion energy, static refractive index, dipole strength, and static optical dielectric constant). In addition, nonlinear refractive index, linear optical susceptibility, and third-order nonlinear optical susceptibility are investigated.
Cosmological simulation in tides: power spectra, halo shape responses, and shape assembly bias
Authors: Akitsu Kazuyuki , Li Yin , Okumura Teppei 
Published: April 2021

Abstract
The well-developed separate universe technique enables
accurate calibration of the response of any observable to an
isotropic long-wavelength density fluctuation. The large-scale
environment also hosts tidal modes that perturb all observables
anisotropically. As in the separate universe, both the long tidal
and density modes can be absorbed by an effective anisotropic
background, on which the interaction and evolution of the short
modes change accordingly. We further develop the tidal simulation
method, including proper corrections to the second order Lagrangian
perturbation theory (2LPT) to generate initial conditions of the
simulations. We measure the linear tidal responses of the matter
power spectrum, at high redshift from our modified 2LPT, and at low
redshift from the tidal simulations. Our results agree
qualitatively with previous works, but exhibit quantitative
differences in both cases. We also measure the linear tidal
response of the halo shapes, or the shape bias, and find its
universal relation with the linear halo bias, for which we provide a
fitting formula. Furthermore, analogous to the assembly bias, we
study the secondary dependence of the shape bias, and discover for
the first time the dependence on the halo concentration and axis
ratio. Our results provide useful insights for studies of the
intrinsic alignment as a source of either contamination or
information. These effects need to be correctly taken into account
when one uses intrinsic alignments of galaxy shapes as a precision
cosmological tool.
Palatini double-well and Coleman-Weinberg potentials with non-minimal coupling
Authors: Bostan Nilay 
Published: April 2021

Abstract
We present the impact of non-minimal coupling ξϕ2
R on the inflationary parameters by taking into account the models of single-field inflation with the inflaton that has a non-zero vacuum expectation value (v) after the period of inflation in Palatini gravity. We discuss the well-known symmetry-breaking type potentials, namely the double-well potential and Coleman-Weinberg potential. We show that the inflationary predictions, n
s and r, of these potentials for both ϕ > v and ϕ < v inflation are compatible with the recent measurements within the regions of the v-ξ plane. Finally, we take into account the inflationary predictions of Coleman-Weinberg potential for selected ξ values as a function of v in the Palatini formalism.
Gravitational waves from dark sectors, oscillating inflatons, and mass boosted dark matter
Authors: Bhoonah Amit , Bramante Joseph , Nerval Simran , Song Ningqiang 
Published: April 2021

Abstract
Gravitational wave signatures from dynamical scalar field configurations provide a compelling observational window on the early universe. Here we identify intriguing connections between dark matter and scalars fields that emit gravitational waves, either through a first order phase transition or oscillating after inflation. To study gravitational waves from first order phase transitions, we investigate a simplified model consisting of a heavy scalar coupled to a vector and fermion field. We then compute gravitational wave spectra sourced by inflaton field configurations oscillating after E-Model and T-Model inflation. Some of these gravitational wave signatures can be uncovered by the future Big Bang Observatory, although in general we find that MHz-GHz frequency gravitational wave sensitivity will be critical for discovering the heaviest dark sectors. Intriguingly, we find that scalars undergoing phase transitions, along with E-Model and T-Model potentials, can impel a late-time dark matter mass boost and generate up to Planck mass dark matter. For phase transitions and oscillating inflatons, the largest dark matter mass boosts correspond to higher amplitude stochastic gravitational wave backgrounds.
Primordial non-Gaussianity from G-inflation
Authors: Zhang Fengge , Gong Yungui , Lin Jiong , Lu Yizhou , Yi Zhu 
Published: April 2021

Abstract
Enormous information about interactions is contained in the non-Gaussianities of the primordial curvature perturbations, which are essential to break the degeneracy of inflationary models. We study the primordial bispectra for G-inflation models predicting both sharp and broad peaks in the primordial scalar power spectrum. We calculate the non-Gaussianity parameter f
NL in the equilateral limit and squeezed limit numerically, and confirm that the consistency relation holds in these models. Even though f
NL becomes large at the scales before the power spectrum reaches the peak and the scales where there are wiggles in the power spectrum, it remains to be small at the peak scales. Therefore, the contributions of non-Gaussianity to the scalar induced secondary gravitational waves and primordial black hole abundance are expected to be negligible.
QCD chiral phase transition and critical exponents within the nonextensive Polyakov-Nambu-Jona-Lasinio model *
Authors: Zhao Ya-Peng , Zuo Shu-Yu , Li Cheng-Ming 
Published: April 2021

Abstract
We present a nonextensive version of the Polyakov-Nambu-Jona-Lasinio model that is based on nonextentive statistical mechanics. This new statistics model is characterized by a dimensionless nonextensivity parameter q that accounts for all possible effects violating the assumptions of the Boltzmann-Gibbs (BG) statistics (for

, it returns to the BG case). Based on the nonextensive Polyakov-Nambu-Jona-Lasinio model, we discussed the influence of nonextensive effects on the curvature of the phase diagram at

and especially on the location of the critical end point (CEP). A new and interesting phenomenon we found is that with an increase in q, the CEP position initially shifts toward the direction of larger chemical potential and lower temperature. However, when q is larger than a critical value

, the CEP position moves in the opposite direction. In other words, as q increases, the CEP position moves in the direction of smaller chemical potential and higher temperature. This U-turn phenomenon may be important for the search of CEP in relativistic heavy-ion collisions, in which the validity of BG statistics is questionable due to strong fluctuations and long-range correlations, and nonextensive effects begin to manifest themselves. In addition, we calculated the influence of the nonextensive effects on the critical exponents and found that they remain almost constant with q.
Modelling the visual response to an OUReP retinal prosthesis with photoelectric dye coupled to polyethylene film
Authors: Yamashita Koichiro , Sundaram Prathima , Uchida Tetsuya , Matsuo Toshihiko , Wong Willy 
Published: April 2021

Abstract

Objective. Retinal prostheses have been developed to restore vision in blind patients suffering from diseases like retinitis pigmentosa. Approach. A new type of retinal prosthesis called the Okayama University-type retinal prosthesis (OUReP) was developed by chemically coupling photoelectric dyes to a polyethylene film surface. The prosthesis works by passively generating an electric potential when stimulated by light. However, the neurophysiological mechanism of how OUReP stimulates the degenerated retina is unknown. Main results. Here, we explore how the OUReP affects retinal tissues using a finite element model to solve for the potential inside the tissue and an active Hodgkin–Huxley model based on rat vision to predict the corresponding retinal bipolar response. Significance. We show that the OUReP is likely capable of eliciting responses in retinal bipolar cells necessary to generate vision under most ambient conditions.
Random matrix ensembles in hyperchaotic classical dissipative dynamic systems
Authors: Odavić J , Mali P 
Published: April 2021

Abstract
We study the statistical fluctuations of Lyapunov exponents in the discrete version of the non-integrable perturbed sine-Gordon equation, the dissipative AC- and DC-driven Frenkel–Kontorova model. Our analysis shows that the fluctuations of the exponent spacings in the strictly overdamped limit, which is nonchaotic, conform to an uncorrelated Poisson distribution. By studying the spatiotemporal dynamics, we relate the emergence of the Poissonian statistics to Middleton’s no-passing rule. Next, by scanning values of the DC drive and the particle mass, we identify several parameter regions for which this one-dimensional model exhibits hyperchaotic behavior. Furthermore, in the hyperchaotic regime where roughly fifty percent of the exponents are positive, the fluctuations exhibit features of the correlated universal statistics of the Gaussian orthogonal ensemble (GOE). Due to the dissipative nature of the dynamics, we find that the match between the Lyapunov spectrum statistics and the universal statistics of GOE is not complete. Finally, we present evidence supporting the existence of the Tracy–Widom distribution in the fluctuation statistics of the largest Lyapunov exponent.
AOUP in the presence of Brownian noise: a perturbative approach
Authors: Martin David , Arnoulx de Pirey Thibaut 
Published: April 2021

Abstract
By working in the small persistence time limit, we determine the steady-state distribution of an active Ornstein Uhlenbeck particle (AOUP) experiencing, in addition to self-propulsion, a Gaussian white noise modeling a bath at temperature T. This allows us to derive analytical formulas for three quantities: the spatial density of a confined particle, the current induced by an asymmetric periodic potential and the entropy production rate. These formulas disentangle the respective roles of the passive and active noises on the steady state of AOUPs, showing that signatures of non-equilibrium can display surprising behaviors as the temperature is varied. Indeed, depending on the potential in which the particle evolves, both the current and the entropy production rate can be non-monotonic functions of T. The latter can even diverge at high temperature for steep enough confining potentials. Thus, depending on context, switching on translational diffusion may drive the particle closer to or further away from equilibrium. We then probe the range of validity of our quantitative derivations by numerical simulations. Finally, we explain how the method presented here to tackle perturbatively an Ornstein Uhlenbeck noise could be further generalized beyond the Brownian case.
Free energy fluxes and the Kubo–Martin–Schwinger relation
Authors: Doyon Benjamin , Durnin Joseph 
Published: April 2021

Abstract
A general, multi-component Eulerian fluid theory is a set of nonlinear, hyperbolic partial differential equations. However, if the fluid is to be the large-scale description of a short-range many-body system, further constraints arise on the structure of these equations. Here we derive one such constraint, pertaining to the free energy fluxes. The free energy fluxes generate expectation values of currents, akin to the specific free energy generating conserved densities. They fix the equations of state and the Euler-scale hydrodynamics, and are simply related to the entropy currents. Using the Kubo–Martin–Schwinger relations associated to many conserved quantities, in quantum and classical systems, we show that the associated free energy fluxes are perpendicular to the vector of inverse temperatures characterising the state. This implies that all entropy currents can be expressed as averages of local observables. In few-component fluids, it implies that the averages of currents follow from the specific free energy alone, without the use of Galilean or relativistic invariance. In integrable models, in implies that the thermodynamic Bethe ansatz must satisfy a unitarity condition. The relation also guarantees physical consistency of the Euler hydrodynamics in spatially-inhomogeneous, macroscopic external fields, as it implies conservation of entropy, and the local-density approximated Gibbs form of stationarity states. The main result on free energy fluxes is based on general properties such as clustering, and we show that it is mathematically rigorous in quantum spin chains.
Coherent spin states and stochastic hybrid path integrals
Authors: Bressloff Paul C 
Published: April 2021

Abstract
Stochastic hybrid systems involve a coupling between a discrete Markov chain and a continuous stochastic process. If the latter evolves deterministically between jumps in the discrete state, then the system reduces to a piecewise deterministic Markov process. Well known examples include stochastic gene expression, voltage fluctuations in neurons, and motor-driven intracellular transport. In this paper we use coherent spin states to construct a new path integral representation of the probability density functional for stochastic hybrid systems, which holds outside the weak noise regime. We use the path integral to derive a system of Langevin equations in the semi-classical limit, which extends previous diffusion approximations based on a quasi-steady-state reduction. We then show how in the weak noise limit the path integral is equivalent to an alternative representation that was previously derived using Doi–Peliti operators. The action functional of the latter is related to a large deviation principle for stochastic hybrid systems.
Numerical study of savonius wind turbines performance at Demak coastal area, Indonesia: a comparative study of savonius wind turbines without fin and with fin
Authors: Saputro H , Purdiatama M E , Wijayanto D S , Muslim R , Munir F A 
Published: April 2021

Abstract
The coastline of Demak city shows an increase in the need for electrical energy every year, in line with an increase in pond production. Currently, electricity needs are supplied from diesel generators. However, the use of diesel generators as electricity generators causes pond production costs to increase. On the other hand, the coastal location of Demak has wind potential, which can be used as a power plant. In this study, a numerical study was carried out using the savonius wind turbine as a power plant in the coastal area of Demak city. This research’s initial stage was to collect data on wind characteristics during the day and night conditions. Wind speed data are then used as input parameters in the numerical simulation using the ANSYS R.15 software. This study compares simulations between Savonius wind turbines without using fins and using fins for placement on the coast of Demak. The simulation results show that the wind speed on the coast of Demak ranges from 2 to 3.5 m / s. In these wind conditions, the savonius wind turbine with one fin has a power coefficient (Cp) better than without the fin. The relationship between wind speed and the electric power produced has been simulated and discussed in depth in this paper.