bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing measures of democracy: statistical properties, convergence, and interchangeability
Authors: Vaccaro Andrea
Published: March 2021

By comparing and analysing four cross-national measures of democracy, this article provides novel information regarding the statistical properties, convergence, and interchangeability of some of the most frequently used measures of democracy. The author points out limitations related to the statistical properties of these measures and finds that even if measures of democracy are highly convergent, their interchangeability is weak. This means that the choice of the measure of democracy has considerable consequences for the conclusions of a given study. Especially so in studies covering the last few decades, because the author finds that in general the interchangeability of democracy measures has decreased since the 1980s. In choosing one measure over another, scholars should be aware of the limitations identified in this article. To overcome problems related to weak interchangeability, if a single measure cannot be credibly chosen on theoretical grounds, the author recommends users of the measures to validate their findings with multiple measures of democracy.
Historical effects of shocks on inequality: the great leveler revisited
Authors: van Bavel Bas , Scheffer Marten
Published: March 2021

Inequality of wealth and its associated power has varied greatly over human history. It is often thought that the main levelers of inequality were natural disasters such as epidemics or earthquakes, and social turmoil such as wars and revolutions. Here we critically review evidence of the effects of such events on inequality from medieval times till the present. We show that in spite of the marked differences in character and direct impact of the shocks we consider, most historical disasters were rather followed by a widening of wealth gaps. This can be understood from the wealth distribution and institutional outlay of these societies at the moment of the shock, which to a large extent shaped both the impact and the institutional measures chosen in response to the crisis. As most societies were characterized by economic and political skewness, the result mostly was a further widening of disparities. Over the centuries, exceptions to this rule have occurred in situations where the ordinary people had strong leverage in shaping the response to the crisis through organizations such as guilds, fraternities, trade unions, cooperatives, and political movements. Our results provide empirical support for the view that in nations where such leverage of ordinary people is weak, the responses to novel crises such as the COVID-19 pandemic may boost inequality.
Magnetic tweezers use flux instead of current to enhance precision
Authors: Fore Meredith
Published: March 2021

A redesign of magnetic tweezers controls their forces using the flux emitted from the blunt end.
Unitary, continuum, stationary perturbation theory for the radial Schrödinger equation
Authors: Hoffmann Scott E.
Published: March 2021

In nonrelativistic quantum mechanics, we require that the free and interacting Hamiltonians be related by a unitary transformation, as has been done by other authors. We then derive a stationary perturbation theory for the radial Schrödinger equation for scattering from a spherically symmetric potential. A resulting advantage over the more commonly used Green function method is that the expression for the interacting state vector is normalized to each order in the coupling constant, unlike, in general, the result of the Green function method. Other authors have applied the unitary transformation concept to time-dependent perturbation theory to give unitarity of the time evolution operator to each order in perturbation theory, with results that show improvement over the standard perturbation theory. In this paper, general formulas are obtained for the phase shifts at the first and second order in the coupling constant. We test the method on a simple system with a known exact solution and find complete agreement between our first- and second-order contributions to the s-wave phase shifts and the corresponding expansion to the second order of the exact solution.
Local unitary classification of generalized Bell state sets in C5⊗C5
Authors: Wang C. H. , Yuan J. T. , Yang Y. H. , Mu G. F.
Published: March 2021

In order to study a large number of generalized Bell states (GBSs) efficiently, it is important to classify them by local unitary (LU) equivalence. For example, there are C254(=12650) sets of four GBSs in C5⊗C5, which greatly exceed the C164(=1820) sets of four GBSs in C4⊗C4, and it is inconceivable to explore these sets directly without prior classification. In this paper, we consider the classification of GBS sets in C5⊗C5. First, two simple and useful characterizations of LU-equivalence of GBS sets are given. Then, one characterization is used to divide all 12 650 sets of four GBSs into eight equivalence classes including six locally distinguishable classes and two classes that cannot be discriminated by one-way local operations and classical communication. The second characterization is powerful and can be used to write a program, by using which all C255(=53130) sets of five GBSs in C5⊗C5 are divided into 21 equivalence classes including 9 locally distinguishable classes and 12 locally indistinguishable classes.
Optimization of twin parallel microstrips based nuclear magnetic resonance probe for measuring the kinetics in molecular assembly in ultra-small samples
Authors: Chen Jiahe , You Xueqiu , Sun Huijun , Tian Jiaqin , Fang Hongxun , Xie Junyao , Huang Yuqing , Chen Zhong
Published: March 2021

We present the design, fabrication, characterization, and optimization of a TPM (twin parallel microstrip)-based nuclear magnetic resonance (NMR) probe, produced by using a low-loss Teflon PTFE F4B high frequency circuit board. We use finite element analysis to optimize the radio frequency (RF) homogeneity and sensitivity of the TPM probe jointly for various sample volumes. The RF homogeneity of this TPM planar probe is superior to that of only a single microstrip probe. The optimized TPM probe properties such as RF homogeneity and field strength are characterized experimentally and discussed in detail. By combining this TPM based NMR probe with microfluidic technology, the sample amount required for kinetic study using NMR spectroscopy was minimized. This is important for studying costly samples. The TPM NMR probes provide high sensitivity to analysis of 5 µl samples with 2 mM concentrations within 10 min. The miniaturized microfluidic NMR probe plays an important role in realizing down to seconds timescale for kinetic monitoring.
Nonhomogeneity of phase state in a dusty plasma monolayer with nonreciprocal particle interactions
Authors: Nikolaev V. S. , Timofeev A. V.
Published: March 2021

A monolayer—quasi-two-dimensional finite system—of Yukawa particles in a harmonic trap is under consideration. The effect of monolayer nonhomogeneity on dynamic properties and melting is studied. The results for two models of particle interactions are compared. The first model includes the reciprocal Yukawa potential and electrostatic harmonic trap. The second model additionally employs the point charge approximation of plasma wakes. It accounts for the nonreciprocity of interactions and anomalous heating of particle motion observed in dusty plasma experiments. It is demonstrated that in the point-wake model, both out-of-plane and in-plane kinetic energies of particles are radially dependent. This effect transforms the spatial distribution of dynamic characteristics in the monolayer. We show that the nonuniformity of monolayer properties might lead to several nonuniform melting scenarios and several scenarios of phase coexistence in the system. In the monolayer without nonreciprocal interactions, molten periphery coexists with a solid core. In the monolayer with plasma wakes, the opposite scenario is observed due to the joint effect of nonreciprocity and structural nonuniformity in the system. A perspective method to determine the position of the phase boundary is proposed.
Two contributions to the dielectric response of polar liquids
Authors: Gavrilov Alexey A. , Kramarenko Elena Yu.
Published: March 2021

In this Note, we study the total conservative force {instead of pure electrostatic force as it was carried out in the work by Gavrilov [J. Chem. Phys. 152, 164101 (2020)]} acting on two charges in a polar liquid using dissipative particle dynamics and coarse-grained molecular dynamics simulations. We show that such force (instead of the electrostatic force) obeys Coulomb’s law at large distances between the charges. Apparently, the dielectric response of a polar liquid (at least, within such coarse-grained models) can be decomposed into two contributions: the reorientation of the dipoles (i.e., electrostatic contribution) and the density redistribution (i.e., volume interaction contribution).
Recent progress in random number generator using voltage pulse-induced switching of nano-magnet: A perspective
Authors: Fukushima Akio , Yamamoto Tatsuya , Nozaki Takayuki , Yakushiji Kay , Kubota Hitoshi , Yuasa Shinji
Published: March 2021

Voltage pulse-driven switching of nano-magnets has gained distinct attention because of its high-speed writing with ultralow power consumption. One of the key advantages is that the external voltage applied to a nano-magnet reduces the magnetic anisotropy energy and excites a precessional motion of magnetization. By adjusting the duration and amplitude of the voltage pulse, a switching probability close to 50% can be attained, suggesting that the magnetic state of nano-magnets can be used as a source for generating binary random numbers (RNs) in principle. Because the bi-directional switching of nano-magnets is induced by unipolar voltage pulses, which is essentially different from the case of spin transfer torque (STT) switching, the results are a mixture of two switching polarities: from parallel (“0” state) to antiparallel (“1” state) and vice versa. Here, we focus our attention on the appearance probabilities of four cases, “00,” “01,” “10,” and “11,” all of which change linearly as functions of voltage. By tuning the probabilities of “00” or “11” to 25%, well-balanced RNs can be generated. A clear advantage of the voltage-pulse driven random number generator (RNG) over the conventional STT-driven one is lower consumption, which enables integration and heavily parallel operations of a large number of RNGs.
A dynamical overview of droplets in the transmission of respiratory infectious diseases
Authors: Zhou Maoying , Zou Jun
Published: March 2021

The outbreak of the coronavirus disease has drawn public attention to the transmission of infectious pathogens, and as major carriers of those pathogens, respiratory droplets play an important role in the process of transmission. This Review describes respiratory droplets from a physical and mechanical perspective, especially their correlation with the transmission of infectious pathogens. It covers the important aspects of (i) the generation and expulsion of droplets during respiratory activities, (ii) the transport and evolution of respiratory droplets in the ambient environment, and (iii) the inhalation and deposition of droplets in the human respiratory tract. State-of-the-art experimental, computational, and theoretical models and results are presented, and the corresponding knowledge gaps are identified. This Review stresses the multidisciplinary nature of its subject and appeals for collaboration among different fields to fight the present pandemic.
Constraining computational modeling of indirect drive double shell capsule implosions using experiments
Authors: Haines Brian M. , Sauppe J. P. , Keiter P. A. , Loomis E. N. , Morrow T. , Montgomery D. S. , Kuettner L. , Patterson B. M. , Quintana T. E. , Field J. , Millot M. , Celliers P. , Wilson D. C. , Robey H. F. , Sacks R. F. , Stark D. J. , Krauland C. , Rubery M.
Published: March 2021

Double shell capsule implosions are an alternative approach to achieving alpha heating on the National Ignition Facility. Current machining techniques construct the outer shell as two hemispheres that are glued together, and the deuterium and tritium (DT) liquid inside the inner shell will be injected by a fill tube. These features introduce asymmetries and jetting that may disrupt the confinement of the DT fuel if not carefully controlled. Simulations indicate that in order to achieve high yields in the laboratory, these features as well as susceptibility to the Rayleigh–Taylor instability (RTI) must be mitigated. Due to uncertainties in computational models and the expense of using the best physics models at adequate resolution in three dimensions, our computational modeling must be constrained by experiments. We report on the results of recent hydrogrowth radiography and dual-axis keyhole experiments with double shell targets that have been used to evaluate our modeling of the outer shell joint as well as the impacts of high-energy x-ray preheat that strongly impacts RTI growth. Our simulations show good agreement with the experimental data and inform several important modeling choices.
Characteristic time for the end monomers of a spherically confined polymer to find a nano-pore
Authors: Hoseinpoor S. Mohammad , Nikoofard Narges , Ha Bae-Yeun
Published: March 2021

Translocation of a polymer through a nano-pore is relevant in a variety of contexts such as passage of RNAs through a nuclear pore and transportation of proteins across a membrane. An essential step in polymer translocation is for the end monomers to search the pore. This process requires a characteristic time, referred to as the “attempt time” in this work. Here, we study the attempt time τ of a confined polymer inside a spherical surface by combining a scaling approach and Langevin dynamics simulations. For a moderately to strongly confined polymer, our results suggest that τ ∼ R3.67 for R > P and τ ∼ R2.67 for R < P, where R is the radius of the spherical surface and P is the persistence length of the polymer. All simulation data obtained for an intermediate range of the volume fraction of monomers ϕ(≲ 0.2) tend to collapse onto each other. This implies that τ does not explicitly depend on ϕ, in agreement with the theoretical predictions. These results will be useful for interpreting translocation as a two-step process: the initial attempt to find the pore and eventual pore crossing.
Large-scale clustering of light small particles in developed turbulence
Authors: Oka Sunao , Watanabe Daiki , Goto Susumu
Published: March 2021

Small solid particles, droplets, and bubbles can form clusters in turbulent flows by the action of coherent vortices. This phenomenon, sometimes called the preferential concentration, was often thought to be most conspicuous when the velocity relaxation time τp of particles is comparable with the Kolmogorov time τη. However, since high-Reynolds number turbulence consists of coherent eddies with different timescales, particles can form clusters even when τp≫τη. We demonstrate, by direct numerical simulations, that light particles with different τp values form clusters around axes of coherent vortices with different sizes in developed turbulence.
Temperature dependence of the transverse piezoelectric properties in the [001]-poled 0.25Pb(In1/2Nb1/2)O3-0.42Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 single crystal with alternating current treatment
Authors: Ma Ming , Xia Song , Song Kexin , Guo Haisheng , Xu Zhuo , Li Zhenrong
Published: March 2021

In this work, the transverse piezoelectric properties of the pre-direct current poled (DCP) 0.25Pb(In1/2Nb1/2)O3-0.42Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (0.25PIN-0.42PMN-0.33PT) single crystals were enhanced by the alternating current treatment (ACT) of 10 kVp/cm (5.8 kVrms/cm), 50 Hz, and 20 cycles. The transverse piezoelectric constant d31 of −1560 pC/N and electromechanical coupling coefficient k31 of 0.92 at room temperature were achieved in the DCP-ACT crystal, which were, respectively, 80% and 11% higher than those of the DCP crystal (d31=−870pC/N,k31=0.83) . Meanwhile, the elastic compliance constant S11E and dielectric permittivity ε33T/ε0 of the DCP-ACT crystal were, respectively, 78% and 46% higher than those of the DCP crystal. Based on the temperature dependence of dielectric properties and resonance curves, the d31, ε33T/ε0, and S11E of the DCP-ACT crystal were higher than those of the DCP crystal in the R phase region. The DCP-ACT crystal also showed a higher TFerro (110 °C) than the DCP crystal (96 °C), which was related to the intermediate phase induced by ACT. The d31 at Tferro of the DCP-ACT crystal can be −3810 pC/N, which was 2.3 times that of the DCP crystal (−1680 pC/N). In the T phase region, the DCP-ACT crystal presented a high ε33T/ε0 and attenuated impedance resonance. Moreover, ACT also affected the ferroelectric to paraelectric phase transition. This could be related to the nanoscale heterogeneous polar region induced by ACT, which enhanced the inhomogeneous state in the relaxor-based ferroelectric single crystal. ACT is a potential way for improving the transverse piezoelectric properties of the PIN-PMN-PT single crystal.
Isolation of target DNA using synergistic magnetic bead transport and electrokinetic flow
Authors: Schneider Lindsay , Cui Francis , Tripathi Anubhav
Published: March 2021

The advent and dissemination of next-generation sequencing (NGS) technologies such as Illumina's sequencing platforms has brought forth vast reductions in the cost, time, and technical difficulties associated with DNA and RNA sequencing. Despite this trend, the workflow required to generate nucleic acid libraries for sequencing remains time-consuming and laborious. The following research proposes a method for simplifying and streamlining this process by replacing the manual washing steps of the common magnetic bead-based cleanup with a novel microfluidic method by integrating magnetic separation and electrokinetic purification (MSEP). Requiring no pumps, pipette mixing, vortexing, or centrifugation, MSEP relies on selective adsorption of target DNA onto the magnetic beads with subsequent transport of beads through a microchannel undergoing an antiparallel electroosmotic flow. The synergetic flow conditions were optimized using a simple electrohydrodynamic flow model. This work demonstrates that MSEP is as effective in eliminating adapter-dimers from the post-ligation library mix as the manual method while also greatly reducing the hands-on time and amount of pipetting required. Although MSEP has been applied specifically toward NGS library preparation at this time, it has the potential to be adapted and employed for any bead-based separation scheme, namely, solid phase extraction, sequence-specific hybridization, and immunoprecipitation on a microscale.
Enhanced cavity coupling to silicon vacancies in 4H silicon carbide using laser irradiation and thermal annealing
Authors: Gadalla Mena N. , Greenspon Andrew S. , Defo Rodrick Kuate , Zhang Xingyu , Hu Evelyn L.
Published: March 2021

Significance

Point defects with coupled photon-spin properties hold much interest as possible qubits for quantum information processes. The studies described here show that prolonged laser irradiation and thermal annealing can enhance the defect–cavity coupling of

V
Si
−

defects embedded in silicon carbide optical cavities. These results provide important insights to researchers seeking to optimize cavity coupling to such defects, affording greater optical outputs, clearer spin signatures, and control of the integrated qubits. The cavities serve as “nanoscopes,” allowing us to 1) map out the neighborhood of defects, 2) understand the influence of neighboring defects on the optical and spin performance of the qubit of interest, and 3) ultimately provide pathways to creating strong cavity coupling to the single defects of interest.
Targeting loss of heterozygosity for cancer-specific immunotherapy
Authors: Hwang Michael S. , Mog Brian J. , Douglass Jacqueline , Pearlman Alexander H. , Hsiue Emily Han-Chung , Paul Suman , DiNapoli Sarah R. , Konig Maximilian F. , Pardoll Drew M. , Gabelli Sandra B. , Bettegowda Chetan , Papadopoulos Nickolas , Vogelstein Bert , Zhou Shibin , Kinzler Kenneth W.
Published: March 2021

Significance

The lack of viable tumor-specific targets continues to thwart efforts to implement selective anticancer drugs in the clinic. Clonal loss of heterozygosity (LOH) occurs in the great majority of human tumors and represents an irreversible genetic alteration present in cancer cells that unequivocally distinguishes them from normal cells. Here, we report the development of NASCAR (Neoplasm-targeting Allele-Sensing CAR), a platform comprising pairwise chimeric receptors for detecting and targeting LOH events in cancer. As proof-of-concept, we demonstrate specific NASCAR T cell responses in models of HLA LOH in vitro and in vivo. This work lays the foundation for future exploration and exploitation of LOH-mediated vulnerabilities for precision cellular immunotherapy.
A Separation-of-Powers Approach to the Supreme Court’s Shrinking Caseload
Authors: Lane Elizabeth A.
Published: March 2021

Since the end of the 1980s the Supreme Court has cut its caseload nearly in half. While this decrease has not gone unnoticed, researchers have largely focused their explanations on institutional factors, such as changes in personnel, creation of the certiorari pool, or an increase in the amount of discretion justices have to set their agenda. Most existing work fails to consider how the preferences of members of Congress and the president also contribute to this staggering decrease. I provide the first systematic examination of how extrainstitutional influences affect the size of the Court’s caseload. I examine the 1951–2016 terms of the Court to reveal that a constraining political environment significantly reduces the number of cases the justices agree to hear each term. These results suggest that the justices consider the preferences of actors in the other branches of government much earlier than their decisions on the merits.
Exploring the x-ray photoabsorption spectrum of sodium in the energy range 1070–1090 eV by elucidating the inner shell excitation transition probabilities
Authors: Suleiman Jamal , Rekik Najeh , Salman Saed , Alshoaibi Adil , Abuzir Alaaedeen R
Published: March 2021

The researchers report on a new study of the x-ray photoabsorption spectrum of sodium near the K-edge, involving the calculations of the excitation energies and the excitation transition probabilities for K-shell and M-shell electron excitations transitions in atomic sodium. The calculations were carried out by employing the ‘multi configuration Dirac–Fock method’, Breit interactions and ‘finite nuclear size corrections’ are included in the calculations, the transition probabilities were convoluted into ‘Breit–Wigner’ line shapes, and single 1s photoionization was also taken into account. In addition, the [1s]np and the [1s3s]ns n′p singlet–triplet energy splitting was calculated. Results of the calculations were compared with previous measurements of the photoabsorption spectrum of sodium near the K-edge, and a very good agreement was observed.
One-dimensional weak antilocalization effect in 1T′-MoTe2 nanowires grown by chemical vapor deposition
Authors: Chen Jiancui , Zhou Zhang , Liu Hongtao , Bian Ce , Zou Yuting , Wang Zhenyu , Zhao Zhen , Wu Kang , Yang Haitao , Shen Chengmin , Cheng Zhi Gang , Bao Lihong , Gao Hong-Jun
Published: March 2021

We present a chemical vapor deposition method for the synthesizing of single-crystal 1T′-MoTe2 nanowires and the observation of one-dimensional weak antilocalization effect in 1T′-MoTe2 nanowires for the first time. The diameters of the 1T′-MoTe2 nanowires can be controlled by changing the flux of H2/Ar carrier gas. Spherical-aberration-corrected transmission electron microscopy, selected area electron diffraction and energy dispersive x-ray spectroscopy (EDS) reveal the 1T′ phase and the atomic ratio of Te/Mo closing to 2:1. The resistivity of 1T′-MoTe2 nanowires shows metallic behavior and agrees well with the Fermi liquid theory (<20 K). The coherence length extracted from 1D Hikami–Larkin–Nagaoka model with the presence of strong spin–orbit coupling is proportional to T
−0.36, indicating a Nyquist electron–electron interaction dephasing mechanism at one dimension. These results provide a feasible way to prepare one-dimensional topological materials and is promising for fundamental study of the transport properties.
Impedance response of electrochemical interfaces: part II-chemisorption
Authors: Huang Jun , Li Chen-Kun
Published: March 2021

Physical modeling helps to acquire fundamental insights from experimental data when electrochemical impedance spectroscopy is employed for mechanistic understandings of electrocatalytic reactions. Herein, we report an analytical model for chemisorption impedance with a consistent treatment of ion transport in the solution and electron transfer on the electrode surface. Our formulation avoids both a priori decoupling of double-layer charging and electron transfer reaction, and a strict separation of double-layer charging and ion transport. Ion transport in the entire solution region is described by the Poisson–Nernst–Planck theory and electron transfer kinetics on the electrode surface by the Frumkin–Butler–Volmer theory. Surface dipoles caused by partially charged chemisorbates are considered. The classical Frumkin–Melik–Gaikazyan model for chemisorption is retrieved as a limiting case. The obtained formula is validated using experimental data of hydrogen adsorption at Pt(111). Characteristic frequencies and asymptotic behaviors of chemisorption impedance are analyzed.
Improving the yield of GaAs nanowires on silicon by Ga pre-deposition
Authors: Wilson D P , Dubrovskii V G , LaPierre R R
Published: March 2021

GaAs nanowire (NW) arrays were grown by molecular beam epitaxy using the self-assisted vapor−liquid−solid method with Ga droplets as seed particles. A Ga pre-deposition step is examined to control NW yield and diameter. The NW yield can be increased with suitable duration of a Ga pre-deposition step but is highly dependent on oxide hole diameter and surface conditions. The NW diameter was determined by vapor-solid growth on the NW sidewalls, rather than Ga pre-deposition. The maximum NW yield with a Ga pre-deposition step was very close to 100%, established at shorter Ga deposition durations and for larger holes. This trend was explained within a model where maximum yield is obtained when the Ga droplet volume approximately equals the hole volume.
Ti3C2T
x
MXene/nitrogen-doped reduced graphene oxide composite: a high-performance electrochemical sensing platform for adrenaline detection
Authors: Chen Shuxian , Shi Min , Xu Quan , Xu Jingkun , Duan Xuemin , Gao Yansha , Lu Limin , Gao Feng , Wang Xiaoqiang , Yu Yongfang
Published: March 2021

Herein, Ti3C2T
x
MXene/N-doped reduced graphene oxide (MXene/N-rGO) composite was employed as the electrocatalyst to construct a new electrochemical sensing platform for the determination of adrenaline (AD). The MXene/N-rGO was synthesized via a facile one-step hydrothermal method, where ethylenediamine acted as a reducing agent and N source. The doped N in rGO served as a bridge between MXene and rGO through tight hydrogen bonds. Scanning electron microscopy showed that large numbers of MXenes with accordion-like morphology were distributed on the surface of the N-rGO. The MXene/N-rGO composite displayed a synergetic catalytic effect for oxidizing AD, originating from the unique catalytic activity of N-rGO and the large surface area and satisfactory conductivity of MXene. These characteristics of composite material led to a remarkable effect on signal amplification for the detection of AD, with a wide linear range from 10.0 nM to 90.0 μM and a low detection limit of 3.0 nM based on a signal to noise ratio of 3. Moreover, the MXene/N-rGO electrode displayed good stability, repeatability, and reproducibility. Additionally, the proposed sensor was successfully applied for voltammetric sensing of AD in urine with recoveries from 97.75% to 103.0%.
Spectro-temporal comparisons of optical emission, absorption, and laser-induced fluorescence for characterizing ns and fs laser-produced plasmas
Authors: Harilal S S , Kautz E J , Jones R J , Phillips M C
Published: March 2021

We performed simultaneous measurement of absorption, emission, and laser-induced fluorescence spectroscopic signatures for determining nanosecond and femtosecond laser-produced plasma’s (LPP) physical properties throughout its lifecycle. Plasmas are produced by focusing either ∼6 ns, 1064 nm pulses from an Nd:YAG or ∼35 fs, ∼800 nm pulses from a Ti:sapphire laser on an Inconel target that contains Al as a minor alloying addition. A continuous-wave narrowband tunable laser was used for performing absorption and fluorescence spectroscopy while a fast-gated detection system was used for emission spectroscopy. The temporal evolution of emission, fluorescence, and absorbance of Al transitions are compared for both ns and fs LPPs. Time-resolved absorbance was also used for evaluating linewidth, lineshape, temperature, and column-averaged atomic number density at late times of ns and fs plasma evolution. Our results demonstrate that lower and excited-state populations of fs LPPs are short-lived in comparison to those in ns plasmas. The lower state population is observed to reach a maximum value earlier in time for the fs plasma versus the ns plasma, while the kinetic temperature for the ns plasma was higher than for the fs plasma at most times of the plasma evolution.
Spatiotemporal variations of the electrical potential on surface dielectric barrier discharges
Authors: Mitsuhashi Kodai , Komuro Atsushi , Suzuki Kento , Natsume China , Ando Akira
Published: March 2021

In this study, the temporal variation of an electric potential distribution was measured in a surface dielectric barrier discharge experiment using the Pockels effect. A branching pattern and homogeneous distribution were respectively observed when positive and negative voltages were applied. When continuous alternating current was applied to the electrode, the spatial distributions of the electric potential significantly changed between the first and subsequent discharge cycles. The results indicate that the electrostatic repulsive forces caused by the residual charges on the dielectric surface affect the dynamic patterns of the discharge morphology.
On the electron energy distribution function in the high power impulse magnetron sputtering discharge
Authors: Rudolph Martin , Revel Adrien , Lundin Daniel , Hajihoseini Hamidreza , Brenning Nils , Raadu Michael A , Anders André , Minea Tiberiu M , Gudmundsson Jón Tómas
Published: March 2021

We apply the ionization region model (IRM) and the Orsay Boltzmann equation for electrons coupled with ionization and excited states kinetics (OBELIX) model to study the electron kinetics of a high power impulse magnetron sputtering (HiPIMS) discharge. In the IRM the bulk (cold) electrons are assumed to exhibit a Maxwellian energy distribution and the secondary (hot) electrons, emitted from the target surface upon ion bombardment, are treated as a high energy tail, while in the OBELIX the electron energy distribution is calculated self-consistently using an isotropic Boltzmann equation. The two models are merged in the sense that the output from the IRM is used as an input for OBELIX. The temporal evolutions of the particle densities are found to agree very well between the two models. Furthermore, a very good agreement is demonstrated between the bi-Maxwellian electron energy distribution assumed by the IRM and the electron energy distribution calculated by the OBELIX model. It can therefore be concluded that assuming a bi-Maxwellian electron energy distribution, constituting a cold bulk electron group and a hot secondary electron group, is a good approximation for modeling the HiPIMS discharge.
Vibration-based inverse graphical technique for thickness estimation of bulk acoustic wave (BAW) resonators: application for corrosion monitoring of sacrificial anodes
Authors: Thalapil Jeslin , Tamhane Durgesh , Banerjee Sauvik , Tallur Siddharth
Published: March 2021

Resonant acoustic sensors have been used in a variety of applications that leverage the large sensitivity of mechanical resonance frequency to shift in geometric or mechanical properties of the sensor induced by the measurand. In applications such as structural health monitoring, accurate damage quantification requires development of precise models for resonator-measurand interactions or advanced system identification or optimization algorithms. In this paper, we utilize a graphical technique originally proposed for damage assessment in beams, to determine the extent of corrosion of sacrificial zinc anode discs instrumented with piezoelectric transducers. We develop analytical models for expressing natural resonance frequencies of the radial and transverse vibration modes of a disc in terms of material and geometric properties of its constituent elements. The underlying parameters (in this case, the thicknesses of the zinc and zinc oxide films) are extracted from measured resonance frequencies by finding roots of the characteristic determinant of these modes through graphical technique. Even though accelerated corrosion induced by impressed current results in non-uniform corrosion of the anode, the graphical technique with uniform-corrosion model shows excellent agreement with experimental results and is suitable for in-situ monitoring of sacrificial anodes used in cathodic protection systems. This technique requires no calibration or model of corrosion dynamics, and is computationally inexpensive unlike optimization techniques.
Enhancing piezoelectric energy harvesting from the flow-induced vibration of a circular cylinder using dual splitters
Authors: Wang Junlei , Gu Shanghao , Abdelkefi Abdessattar , Bose Chandan
Published: March 2021

Ambient energy harvesting from the vortex-induced vibration (VIV) of circular cylinders has been extensively studied in recent years. However, the effect of multiple splitters attached to the cylinder surface in different configurations on the energy harvesting performance is not well understood to date. This study is focused on enhancing the piezoelectric energy harvesting from the flow-induced vibration of a circular cylinder by using two symmetric splitters in different relative angular positions with respect to the oncoming uniform flow. Both wind tunnel experiments and numerical simulations are carried out to study the effect of seven different installation angles (α = 0∘, 30∘, 60∘, 90∘, 120∘, 150∘, and 180∘) of the dual splitters on the energy harvesting efficiency with the increasing flow velocity. It is observed that, in the absence of any splitter, the energy harvesting performance is constricted to the lock-in regime for the VIV of the circular cylinder. When the dual splitters are introduced at the positions of 0∘ and 120∘, energy harvesting is completely suppressed, and no voltage is generated. The transition from VIV to galloping is observed for the positions of 30∘, 60∘, 150∘, and 180∘. Among them, 60∘ is the optimal position, where the maximum output voltage increases up to 188.61% of that obtained from the harvester without any splitters. VIV with a reduced maximum output voltage is observed at the position of 90∘. The underlying vortex interactions behind the transitional dynamics are investigated by analyzing the flow-field. It is observed that the vortex formation length increases with the increase in the splitter angle, and the secondary vortices also play a key role behind the VIV to galloping transition. This study systematically carries out the performance analysis of the VIV-based energy harvester with multiple splitters for the first time in the literature and directly contributes to the optimized design of an innovative wind energy harvester with multiple splitter configuration.
Superconducting nanostrip single-photon detectors some fundamental aspects in detection mechanism, technology and performance
Authors: Semenov Alexej D
Published: March 2021

The paper is devoted to several recent rather fundamental achievements in the field of superconducting nanostrip single-photon detectors which make an impact on understanding the detection mechanism, technological challenges and performance metrics important for applications. Special attention is given to static and temporal fluctuations of different origin affecting key metrics of these detectors. Some salient points of older models such as detection criteria or real-time evolution of an electro-thermal domain are also highlighted. Recent technical and instrumental advances are intentionally left beyond the scope of this paper.
Coherent one-way quantum conference key agreement based on twin field
Authors: Cao Xiao-Yu , Gu Jie , Lu Yu-Shuo , Yin Hua-Lei , Chen Zeng-Bing
Published: March 2021

Quantum conference key agreement (CKA) enables key sharing among multiple trusted users with information-theoretic security. Currently, the key rates of most quantum CKA protocols suffer from the limit of the total efficiency among quantum channels. Inspired by the coherent one-way and twin-field quantum key distribution (QKD) protocols, we propose a quantum CKA protocol of three users. Exploiting coherent states with intensity 0 and μ to encode logic bits, our protocol can break the limit. Additionally, the requirements of phase randomization and multiple intensity modulation are removed in our protocol, making its experimental demonstration simple.
Non-oscillatory no-scale inflation
Authors: Ellis John , Nanopoulos Dimitri V. , Olive Keith A. , Verner Sarunas
Published: March 2021

We propose a non-oscillatory no-scale supergravity model of
inflation (NO-NO inflation) in which the inflaton does not oscillate
at the end of the inflationary era. Instead, the Universe is then
dominated by the inflaton kinetic energy density (kination). During
the transition from inflation to kination, the Universe preheats
instantly through a coupling to Higgs-like fields. These rapidly
annihilate and scatter into ultra-relativistic matter particles,
which subsequently dominate the energy density, and reheating occurs
at a temperature far above that of Big Bang Nucleosynthesis. After
the electroweak transition, the inflaton enters a tracking phase as
in some models of quintessential inflation. The model predictions
for cosmic microwave background observables are consistent with
Planck 2018 data, and the density of gravitational waves is below
the upper bound from Big Bang Nucleosynthesis. We also find that the
density of supersymmetric cold dark matter produced by gravitino
decay is consistent with Planck 2018 data over the expected range of
supersymmetric particle masses.
Constraints on a mixed model of dark matter particles and primordial black holes from the galactic 511 keV line
Authors: Cai Rong-Gen , Ding Yu-Chen , Yang Xing-Yu , Zhou Yu-Feng
Published: March 2021

The galactic 511 keV gamma-ray line has been observed since 1970's, and was identified as the result of electron-positron annihilation, but the origin of such positrons is still not clear.
Apart from the astrophysical explanations, the possibilities that such positrons come from dark matter (DM) annihilation are also widely studied.
Primordial black hole (PBH) is also an extensively studied candidate of DM.
If PBHs exist, the DM particles may be gravitationally bound to the PBHs and form halo around PBHs with density spikes.
DM annihilation in these density spikes can enhance the production rate of positrons from DM particles, but the signal morphology is similar to the decaying DM.
We consider such a mixed model consisting of DM particles and PBHs and obtain the upper limit from the data of 511 keV gamma-ray line from INTEGRAL/SPI on the decaying component of DM particles and the constraint on the PBH abundance.
These constraints are general and independent of particle DM models.
For the mixed model consisting of excited DM and PBHs, the constraints on the PBH abundance can be down to O(10-17) for DM particle with mass around 1, which is more stringent than that obtained from the extragalactic gamma-ray background.
Impacts of the physical data model on the forward inference of initial conditions from biased tracers
Authors: Nguyen Nhat-Minh , Schmidt Fabian , Lavaux Guilhem , Jasche Jens
Published: March 2021

We investigate the impact of each ingredient in the employed physical data model on the Bayesian forward inference of initial conditions from biased tracers at the field level. Specifically, we use dark matter halos in a given cosmological simulation volume as tracers of the underlying matter density field. We study the effect of tracer density, grid resolution, gravity model, bias model and likelihood on the inferred initial conditions. We find that the cross-correlation coefficient between true and inferred phases reacts weakly to all ingredients above, and is well predicted by the theoretical expectation derived from a Gaussian model on a broad range of scales. The bias in the amplitude of the inferred initial conditions, on the other hand, depends strongly on the bias model and the likelihood.
We conclude that the bias model and likelihood hold the key to an unbiased cosmological inference. Together they must keep the systematics — which arise from the sub-grid physics that are marginalized over — under control in order to obtain an unbiased inference.
Beginning of a new phase of the dissemination of the kilogram
Authors: Davidson S , Stock M
Published: March 2021

Following the completion of the first key comparison of realizations of the kilogram, CCM.M-K8.2019, the internationally coordinated dissemination of the kilogram has entered into a new phase on 1 February 2021. The traceability of the mass unit to the Planck constant will now be taken from the ‘consensus value’ of the kilogram. This letter provides the background on the phases of the dissemination of the kilogram and describes the determination of the consensus value and its consequences for mass traceability.
Information thermodynamics of financial markets: the Glosten–Milgrom model
Authors: Touzo Léo , Marsili Matteo , Zagier Don
Published: March 2021

The Glosten–Milgrom model describes a single asset market, where informed traders interact with a market maker, in the presence of noise traders. We derive an analogy between this financial model and a Szilárd information engine by (i) showing that the optimal work extraction protocol in the latter coincides with the pricing strategy of the market maker in the former and (ii) defining a market analogue of the physical temperature from the analysis of the distribution of market orders. Then we show that the expected gain of informed traders is bounded above by the product of this market temperature with the amount of information that informed traders have, in exact analogy with the corresponding formula for the maximal expected amount of work that can be extracted from a cycle of the information engine. This suggests that recent ideas from information thermodynamics may shed light on financial markets, and lead to generalised inequalities, in the spirit of the extended second law of thermodynamics.
Synthesis and characterization of triazol derivative as new corrosion inhibitor for mild steel in 1M HCl solution complemented with antibacterial studies
Authors: Kadhim Abdulhadi , Sulaiman Ghassan , Abdel Moneim Ahmed E. , Yusop Rahimi M. , Al-Amiery Ahmed
Published: March 2021

One of the most serious problems in the industry in which mild steel is used is corrosion. Billions of dollars are lost every year due to corrosion problems, especially in industries that use acids, especially hydrochloric acid, where hydrochloric acid has an important role in industrial processes, in refining crude oil, pickling acid, industrial cleaning, acid sizing, and in petrochemical processes. New inhibitor derived from triazole namely “methyl 2-(1-(5-methyl-1-(p-tolyl)-1H-1,2,3-triazol-4-yl)ethylidene)hydrazinecarbodithioate” (MTH) has been synthesized and fully characterized by Fourier transformer infra-red (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopically techniques in addition to CHN analysis. The new compound has been tested as new corrosion inhibitor for mild steel in hydrochloric acid solution. The inhibition performance of new corrosion inhibitor was investigated by weight loss method. Results demonstrate that the corrosion rate (CR) decreased significantly in the presence MTH. On the other hand, the inhibition efficiency, increased with the increase of the concentration of MTH up to 95.1% achieved at 303 K for a 0.5mM concentration. The inhibition efficiency decreases with temperature increase. The antimicrobial activities of MTH forEscherichia coliandStaphylococcus aureushave been investigated. The results revealed that the MTH has satisfactory activities against the tested bacteria. The corrosion of mild steel is one of the most serious problems in the industry. Billions of dollars are lost every year due to the corrosion problems, especially in industries that use acids such as especially hydrochloric acid, where it has an important role in industrial processes, in refining crude oil, pickling acid, industrial cleaning, acid sizing, and in petrochemical processes. New inhibitor derived from triazole namely “methyl 2-(1-(5-methyl-1-(p-tolyl)-1H-1,2,3-triazol-4-yl) ethylidene) hydrazinecarbodithioate” (MTH) has been synthesized and fully characterized by Fourier Transformer Infra-Red (FT-IR) and Nuclear Magnetic Resonance (NMR) as a spectroscopic technique. In addition to CHN analysis. The new compound has been tested as a new corrosion inhibitor for mild steel in hydrochloric acid solution. The inhibition performance of new corrosion inhibitor was studied by weight loss method. The results demonstrates that the corrosion rate (CR) decreased significantly in the presence of an MTH. On the other hand, the inhibition efficiency was increased with the increase in the concentration of MTH up to 95.1% achieved at a temperature of 303 °K for a concentration of 0.5mM. The inhibition efficiency was decreases with increasing temperature. The antimicrobial activities of MTH forE. coliandS. aureushave been investigated. The results revealed that the MTH has satisfactory activities against the tested bacteria.
FABRICATION OF ANTIBACTERIAL MATERIAL USING DIFFERENT ACETATE SALTS
Authors: Hashim Mustafa Sh. , Hussein Hadi A. , Khaleel Reem S. , Kadum Maha M.
Published: March 2021

Ammonium, Cadmium, Cobalt, Sodium and Magnesium acetates were diluted inside both distilled water and Isopropanol alcohol separately and then tested as antibacterial material against (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella sp. and Candida albicans). Among diluted salts in water only Cadmium and Cobalt acetate had inhibition zones. The particles sizes inside distilled water were 5.6 and 25.5 nm for diluted Cadmium and Cobalt acetate respectively as measured by particle size distribution test. The addition of all used acetate salts on Isopropanol alcohol increased its ability for killing tested bacteria. All diluted acetates in Isopropanol alcohol had inhibition zones, both Cadmium and Cobalt acetates had equal or larger inhibition zones than those diluted in water. Minimum bactericidal concentration (MBC), minimal inhibitory concentration (MIC) and biofilm inhibition% were measured for Cadmium acetate and cobalt acetate.