bluuebunny/crossref_metadata_2025 huggingface dataset:
Microparticle sorting with a virtual optical chip
Authors: Zhou Quan , Xia Tian , Liao Wei , Liu Yu , Lin Danping , Yang Jianhe , Tao Shaohua
Published: May 2021

We proposed an automatic sorting method based on a virtual optical chip, which was formed by a complex-amplitude beam shaping system. The automatic sorting of different micro-particles was realized by the optical forces of the intensity and phase gradients of the reconstructed optical beam. The method was verified with theoretical analysis and experimental results. Compared with the traditional optical sorting methods, the proposed one does not need high-precision mechanical and/or microfluidic devices. The optical chip is flexible in structure and efficient in optical sorting and can be used in the fields of medical detection and material sensing.
Origins of nanoscale emission inhomogeneities of high content red emitting InGaN/InGaN quantum wells
Authors: Samuel B. , Cooper D. , Rochat N. , Mavel A. , Barbier F. , Dussaigne A.
Published: May 2021

The origin of the nanoscale emission inhomogeneities of red emitting InGaN/InGaN quantum wells (QWs) grown directly on a GaN template and on an InGaN on sapphire (InGaNOS) substrate is investigated. InGaNOS is a partly relaxed InGaN pseudo-substrate fabricated by Soitec. As the latter approach provides an interesting optical internal quantum efficiency of 6.5% at 624 nm at 290 K, a deeper study, at the microstructure level, was conducted. The emission inhomogeneities on InGaNOS were highlighted by cathodoluminescence wavelength mappings where three areas were chosen: one emitting at a shorter wavelength, i.e., 588 nm, and two at a longer wavelength, i.e., 607 and 611 nm. Specimens from these zones were extracted by focused ion beam milling to perform cross-sectional characterization techniques. High-angle annular dark field scanning transmission electron microscopy images demonstrated that, while red emitting areas present homogeneous QWs, shorter wavelength areas exhibit non-uniform QWs, in terms of thickness and In composition. Complementary deformation mappings in the growth direction obtained by geometrical phase analysis show that longer emission wavelengths are originating from homogeneous QWs with an InN mole fraction evaluated at 39.0 ± 1.5%. This result demonstrates the possibility of achieving red emission with a coherent (In,Ga)N alloy when using an adapted substrate. A comparison of identical QWs grown on a GaN template is also given.
Broadband angular color stability of dielectric thin film-coated pyramidal textured Si for photovoltaics
Authors: Roosloot N. , Neder V. , Haug H. , You C. C. , Polman A. , Marstein E. S.
Published: May 2021

In this work we demonstrate the angular color stability of textured c-Si substrates colored by single layer thin film coatings of SiNx. These coatings show higher angular color stability on substrates with a random upright pyramidal surface texture compared to identical coatings on planar silicon substrates. Angle dependent reflectance measurements, supported by a modeling framework, display that the reflectance peaks originating from thin film interference of coated textured substrates only shift about 15 nm with an increasing angle of incidence from 10° to 80°, while the reflectance peaks of planar substrates with identical coatings shift about 120 nm at these angles. More specifically, reflectance peaks of planar substrates shift to shorter wavelengths, leading to a blue shift of the color appearance. The stable peak position of the textured samples is explained by a 2D representation of their surface texture and the primarily double interference interaction on it. While it is well known that a wide range of colors can be realized exhibiting low optical losses with thin film coatings, angular color stability was often not taken into account. However, for building integrated photovoltaics applications, a high angular color stability is desired, underlining the importance of using these textures. In most installed c-Si photovoltaics, similar substrate surface textures and dielectric thin film layers are already used. Therefore, this work envisions a route to facilitate large scale production of colored solar cells on textured c-Si substrates, colored by thin film SiNx layers, with minimized optical losses and improved angular color stability.
Observation of fully detached divertor integrated with improved core confinement for tokamak fusion plasmas
Authors: Wang H. Q. , Wang L. , Ding S. , Garofalo A. M. , Gong X. Z. , Eldon D. , Guo H. Y. , Leonard A. W. , Hyatt A. W. , Qian J. P. , Weisberg D. B. , McClenaghan J. , Fenstermacher M. E. , Osborne T. H. , Lasnier C. J. , Watkins J. G. , Shafer M. W. , Grierson B. A. , Xu G. S. , Yan Z. , Mckee G. R. , Huang J. , Ren J. , Buttery R. J. , Humphreys D. A. , Thomas D. M. , Zhang B. , Liu J. B.
Published: May 2021

Integration of divertor detachment with a high-performance (βN ∼ 3, βp > 2, H98 ∼ 1.5) core plasma has been demonstrated in DIII-D high-βp (poloidal beta) plasmas associated with a sustained core internal transport barrier (ITB) and an H-mode edge transport barrier (ETB). Such good core-edge integration has been achieved for both neon and nitrogen seeding, for both favorable and unfavorable B-field directions, independently from the impurity puffing locations, though these variations play important roles on divertor characteristics. Compared to the standard H-mode plasmas, the high-βp plasma exhibits a much wider window of detachment compatible with high confinement core. Fully detached divertor plasmas with low plasma temperature (Te < 5 eV), low particle flux, and low heat flux across the entire divertor target plate were obtained by using nitrogen seeding. This detached high-βp plasma is compatible with a newly developed detachment control system which can help optimize the nitrogen gas flow rate. Several features, i.e., the high edge safety factor in the high-βp scenario, impurity injection, closed divertor and reduced heating power requirement due to the high confinement, facilitate the achievement of full divertor detachment at lower density. Instead of degrading global performance, the divertor detachment facilitates the access to an even stronger ITB at large radius with a relatively weak ETB through self-organized synergy between ITB and ETB, leading to sustained high confinement. The strengthening of the large-radius ITB compensates for the ETB degradation associated with divertor detachment. In addition, a weak ETB naturally has smaller edge localized modes (ELMs). In particular, with neon injection, a long-period no-ELM H-mode phase has been achieved simultaneously with high-performance core and partially detached divertor plasmas. These results demonstrate the possibility of integrating excellent core plasma performance with an effective divertor solution, an essential step toward steady-state operation of reactor-grade plasmas.
Information upper bound for McKean–Vlasov stochastic differential equations
Authors: Lv Li , Zhang Yanjie , Wang Zibo
Published: May 2021

We develop an information-theoretic framework to quantify information upper bound for the probability distributions of the solutions to the McKean–Vlasov stochastic differential equations. More precisely, we derive the information upper bound in terms of Kullback–Leibler divergence, which characterizes the entropy of the probability distributions of the solutions to McKean–Vlasov stochastic differential equations relative to the joint distributions of mean-field particle systems. The order of information upper bound is also figured out.
Phonon-mediated crystal detectors with metallic film coating capable of rejecting α and β events induced by surface radioactivity
Authors: Bandac I. C. , Barabash A. S. , Bergé L. , Bourgeois Ch. , Calvo-Mozota J. M. , Carniti P. , Chapellier M. , deCombarieu M. , Dafinei I. , Danevich F. A. , Dumoulin L. , Ferri F. , Giuliani A. , Gotti C. , Gras Ph. , Guerard E. , Ianni A. , Khalife H. , Konovalov S. I. , Loaiza P. , Madhukuttan M. , deMarcillac P. , Mariam R. , Marnieros S. , Marrache-Kikuchi C. A. , Martinez M. , Nones C. , Olivieri E. , Pessina G. , Poda D. V. , Redon Th. , Scarpaci J.-A. , Tretyak V. I. , Umatov V. I. , Zarytskyy M. M. , Zolotarova A. S.
Published: May 2021

Phonon-mediated particle detectors based on single crystals and operated at millikelvin temperatures are used in rare-event experiments for neutrino physics and dark-matter searches. In general, these devices are not sensitive to the particle impact point, especially if the detection is mediated by thermal phonons. In this Letter, we demonstrate that excellent discrimination between interior and surface β and α events can be achieved by coating a crystal face with a thin metallic film, either continuous or in the form of a grid. The coating affects the phonon energy downconversion cascade that follows the particle interaction, leading to a modified signal shape for close-to-film events. An efficient identification of surface events was demonstrated with detectors based on a rectangular 20×20×10 mm3 Li2MoO4 crystal coated with a Pd normal-metal film (10 nm thick) and with Al–Pd superconductive bi-layers (100 nm-10 nm thick) on a 20 × 20 mm2 face. Discrimination capabilities were tested with 238U sources emitting both α and β particles. Surface events are identified for energy depositions down to millimeter-scale depths from the coated surface. With this technology, a substantial reduction of the background level can be achieved in experiments searching for neutrinoless double-beta decay.
An effective method to avoid charge leakage along the surface in voltage response measurement
Authors: Sun Yunlong , Li Zhonghua , Han Yongsen , Suo Changyou
Published: May 2021

The voltage response measurement is a non-destructive method to diagnose the aging condition of insulation and is used extensively. The characteristics about the volume polarization and resistance can be obtained by analyzing the measured decay or return voltage of a charged dielectric, which is important for aging diagnosis. To eliminate the influence of the charges leaking along the sample surface on the voltage response analysis, we present an effective three electrode configuration with a potential guard electrode. The voltage decay results show that adopting electrodes with a potential guard electrode can effectively avoid charge leakage along the sample surface.
Frontiers of stochastic electronic structure calculations
Authors: Morales-Silva Miguel A. , Jordan Kenneth D. , Shulenburger Luke , Wagner Lucas K.
Published: May 2021

In recent years there has been a rapid growth in the development and application of new stochastic methods in electronic structure. These methods are quite diverse, from many-body wave function techniques in real space or determinant space to being used to sum perturbative expansions. This growth has been spurred by the more favorable scaling with the number of electrons and often better parallelization over large numbers of central processing unit (CPU) cores or graphical processing units (GPUs) than for high-end non-stochastic wave function based methods. This special issue of the Journal of Chemical Physics includes 33 papers that describe recent developments and applications in this area. As seen from the articles in the issue, stochastic electronic structure methods are applicable to both molecules and solids and can accurately describe systems with strong electron correlation. This issue was motivated, in part, by the 2019 Telluride Science Research Center workshop on Stochastic Electronic Structure Methods that we organized. Below we briefly describe each of the papers in the special issue, dividing the papers into six subtopics.
Transient Analysis of Variable- and Fixed-Speed Wind Turbines
Authors: Okedu Kenneth
Published: May 2021

Variable speed wind turbines based on doubly fed induction generators (DFIGs) are heavily stressed during grid faults, and thus tend to lose their independent controllability of active and reactive powers. Fixed-speed wind turbines based on induction generators (IGs) are also heavily stressed during grid faults, but do not have independent controllability of active and reactive powers like the DFIGs. This chapter investigates the transient stability of DFIGs and IGs during grid fault. Simulation results in power system computer aided design and electromagnetic transient including DC (PSCAD/EMTDC) show that a DFIG is more stable during grid faults because it can assume its steady state after the fault, due to the provision of reactive power by its power converters. On the other hand, an IG cannot return to its steady state because its reactive power consumption is high during transient, and hence needs external reactive power compensation.
Wind farm stabilization using external and non-external reactive power compensation
Authors: Okedu Kenneth
Published: May 2021

This chapter presents the stability improvement of a wind farm during wind speed change and a three-phase fault close to the wind farm gained as a result of using an external flexible AC transmission system (FACTS) reactive power compensation device. Two cases were considered where the external reactive compensation device was connected and disconnected from the wind farm. Simulation results in Power System Computer Aided Design and Electromagnetic Transient Including DC (PSCAD/EMTDC) show that, with the external reactive power compensation device connected, the wind farm could be effectively stabilized both in dynamic and transient conditions. A further analysis was carried out using a simple model of a variable-speed wind turbine system to show how the wind farm could be stabilized without external reactive power compensation.
Effects of load capacity and ECS timing constant parameter on the dynamic behavior of grid connected wind farms
Authors: Okedu Kenneth
Published: May 2021

The control of grid frequency in a power system is vital in order to maintain the frequency of the system within its nominal value. In this chapter, the dynamic behavior of a grid connected wind farm composed of a squirrel cage induction generator is presented. The considered grid is composed of steam turbines connected to the wind farm. An energy capacitor system is used to stabilize the wind farm during periods of wind speed change. Loads of various capacities are connected to the grid in order to test the robustness of the controllers of the energy capacitor system. Furthermore, the timing constant of the inbuilt DC–DC chopper of the energy capacitor system was varied considering the network having various load capacities. The system performance was evaluated using Power System Computer Design and Electromagnetic Transient Including DC (PSCAD/EMTDC). The same conditions of operation were used in investigating the various scenarios for effective comparison. The natural wind speed employed was the same for all the scenarios. The presented results show that small load capacity with high value of low pass filter time constant gave better responses of the grid frequency and the entire variables of the power network.
Impact of power converter size on variable speed wind turbines
Authors: Okedu Kenneth
Published: May 2021

The effect of the power capacity size of a variable-speed wind turbine during grid fault is investigated. Power converter capacity sizes of 20%, 25%, and 30% of the rated wind generator power were used in the analysis. A simple model of aggregated doubly fed induction wind generators connected to an infinite bus bar was analyzed in the study. A severe (worst case) three-line to grid fault (3LG) was applied to the model system, to demonstrate the effect of the power converter sizes. Simulations were carried out in standard laboratory Power System Computer Aided Design and Electromagnetic Transient Including DC (PSCAD/EMTDC). The simulation results show that the higher the power converter capacity of the variable-speed wind turbine, the better the performance during grid fault in the power system. This is because more reactive power could be injected into the power system during the short transient or disturbance in the power network.
Enhancing Frequency of Grid-Connected Wind Farms using energy capacitor systems and trap RC shunt damper strategies
Authors: Okedu Kenneth
Published: May 2021

The increase of penetration of wind farms into existing grid connected systems definitely affects the frequency and stability of the power networks. Power electronic converters are used to interface the generated energy into the grid. However, these voltage source converters produce unwanted harmonics. As a result, filters are used to smooth the output of the network. In this chapter, a combination of the conventional energy capacitor system and a proposed two-trap RC shunt damper circuitry is used to stabilize the grid network made up of a fixed-speed wind turbine, steam turbines, and hydro turbines. The energy storage system is connected to the terminals of the wind farm and can provide reactive power to the grid network duing wind speed changes. The two-trap damper has the ability to mitigate the mechanical vibration of the wind turbine and increase its output and rotor speed acceleration during disturbances; as a result the turbine speed is reduced. Simulations were run in the Power System Computer Aided Design and Electromagnetic Transient Including DC (PSCAD/EMTDC) environment for scenarios when grid frequency control was not implemented, and when frequency control was employed using the energy storage device.
Perspectives
Authors: Okedu Kenneth
Published: May 2021

Onshore Wind Farms: Dynamic Stability and Applications in Hydrogen Production offers an up-to-date discussion of new technologies and methods for building wind farms and upgrading existing wind turbines. The effective operation of grid-connected wind farms is quite a challenge for grid operators, largely due to the transient nature of wind energy. This book covers improvements in dynamic performance of a grid in combination with other sources including nuclear power, hydropower, and thermal turbines. It investigates the effects of devices and control strategies that potentially improve wind energy capture and stabilize existing fixed-speed wind turbines in grid-connected wind farms.

This timely book:Includes new technology for improved wind turbinesFeatures developments for improving the stability of grids that rely on wind powerCovers applications such as hydrogen fuel production and DC fuel cells

Relevant for researchers and engineers working in wind energy, this book is also suitable for students interested in grid development or other forms of renewable energy. It is also of interest to wind energy policy planners and analysts.
Genetics of physiological and agronomical traits linked to salinity tolerance in tomato
Authors: Moradi Mohammad , Dehghani Hamid , Ravari Sied Zabihallah
Published: May 2021

Improvement of tomato (Lycopersicon esculentum L.) for growth in saline soils is a major goal of tomato breeders. The aim of this study was to identify the genetic combining ability and genetics of salinity tolerance in tomato. Plant materials were grown under normal (NG) and salinity stress (SSG) conditions. Results showed that the genetic controlling mechanism of salinity-related traits and fruit weight is complex and that all genetic components of additive, non-additive and maternal are involved. The nature of gene action for fruit weight and salinity-related traits was significantly affected by salinity stress. Dominance and additive gene action were predominant under NG and SSG, respectively. Under NG, the best general combiner parent for fruit weight was P3 (salt-tolerant with moderate fruit yield). Under SSG, P1 (highly salt-tolerant with low fruit yield) was the best general combiner parent for fruit weight and exhibited high genetic combining ability for K+/Na+, lipoxygenase activity, proline, relative water content, total carbohydrate and cell membrane stability. With the high frequency of genes effective in salt tolerance, the P1 parent appeared as the best specific mating partner with other parents under SSG. Simultaneous selection for fruit weight and surrogate traits (cell membrane stability, proline and relative water content) in a population derived from the P1 × P5 (susceptible with high fruit yield) cross could result in a salt-tolerant tomato genotype.
Toll9 fromBombyx morifunctions as a pattern recognition receptor that shares features with Toll-like receptor 4 from mammals
Authors: Zhang Ruonan , Li Xiaofeng , Zhang Jie , Li Yanjun , Wang Yuan , Song Yuhang , Ren Feifei , Yi Huiyu , Deng Xiaojuan , Zhong Yangjin , Cao Yang , Strand Michael R. , Yu Xiao-Qiang , Yang Wanying
Published: May 2021

Significance

Toll/Toll-like receptors are key regulators of the innate immune system in both invertebrates and vertebrates. However, while mammalian Toll-like receptors function as pattern recognition receptors that directly bind microbe-associated ligands, arthropod Tolls are generally thought to be activated by Spätzle cytokines. Here, we show that Toll9 from the silkmothBombyx morifunctions as a pattern recognition receptor that binds lipopolysaccharide. Our results provide a link for both structural and functional conservation between an insect Toll and a mammalian Toll-like receptor family member.
Zoonotic diseases: a One Health perspective
Authors: Samadi Assadullah , Hailat Nabil
Published: May 2021

The emergence and re-emergence of infectious diseases including zoonoses and persistence of neglected zoonotic diseases threaten the global health and economy of rural societies now more than any time in the history of humanity. Animals are the main reservoirs of zoonotic disease agents, and zoonotic pathogens are transmitted to humans by direct contacts with infected animals or indirectly through animal products and the environment. A range of factors contribute in persistence and emergence of zoonoses, and globalization, climate change, and lack of proper coordination among the governmental organization responsible for human and animal health are the key indicators. Given the shared nature of zoonotic diseases and the spread, emergence, and re-emergence of zoonotic diseases in human and animal populations, integrated One Health is the only effective approach to solve this most important health issue. In this article, different aspects of zoonotic diseases, their role in incremental poverty, and the needs for integrated activities for their control and management are reviewed and discussed in detail.
National Trauma and Substance Use Disorders: A Slippery Slope in Lebanon
Authors: Bizri Maya , El Hayek Samer , Beaini Hadi , Kobeissy Firas , Talih Farid
Published: May 2021

Lebanon, a small middle-income nation in western Asia, has been crippled by decades of political turmoil and armed conflict. A “quadruple crisis” hit the country over the past years, starting with the protracted humanitarian Syrian refugee crisis, followed by a severe socioeconomic collapse, the global COVID-19 pandemic, and lastly the Beirut port catastrophic blast. With the exposure to repetitive traumatic events and associated organic brain injury, the Lebanese population has become at a higher risk of addiction, among other psychiatric comorbidities. With the scarce statistics about the topic and limited addiction services in the country, collaborative local efforts and international help are urgently needed to fight the upcoming substance use epidemic. Raising awareness, providing adequate training, and securing resources for the management of both addiction and trauma are of utmost importance.
Teasing out function from morphology: Similarities between primary cilia and immune synapses
Authors: Douanne Tiphaine , Stinchcombe Jane C. , Griffiths Gillian M.
Published: May 2021

Immune synapses are formed between immune cells to facilitate communication and coordinate the immune response. The reorganization of receptors involved in recognition and signaling creates a transient area of plasma membrane specialized in signaling and polarized secretion. Studies on the formation of the immune synapse between cytotoxic T lymphocytes (CTLs) and their targets uncovered a critical role for centrosome polarization in CTL function and suggested a striking parallel between the synapse and primary cilium. Since these initial observations, a plethora of further morphological, functional, and molecular similarities have been identified between these two fascinating structures. In this review, we describe how advances in imaging and molecular techniques have revealed additional parallels as well as functionally significant differences and discuss how comparative studies continue to shed light on the molecular mechanisms underlying the functions of both the immune synapse and primary cilium.
CaMKII inhibition reduces arrhythmogenic Ca2+ events in subendocardial cryoinjured rat living myocardial slices
Authors: Dries Eef , Bardi Ifigeneia , Nunez-Toldra Raquel , Meijlink Bram , Terracciano Cesare M.
Published: May 2021

Spontaneous Ca2+ release (SCR) can cause triggered activity and initiate arrhythmias. Intrinsic transmural heterogeneities in Ca2+ handling and their propensity to disease remodeling may differentially modulate SCR throughout the left ventricular (LV) wall and cause transmural differences in arrhythmia susceptibility. Here, we aimed to dissect the effect of cardiac injury on SCR in different regions in the intact LV myocardium using cryoinjury on rat living myocardial slices (LMS). We studied SCR under proarrhythmic conditions using a fluorescent Ca2+ indicator and high-resolution imaging in LMS from the subendocardium (ENDO) and subepicardium (EPI). Cryoinjury caused structural remodeling, with loss in T-tubule density and an increased time of Ca2+ transients to peak after injury. In ENDO LMS, the Ca2+ transient amplitude and decay phase were reduced, while these were not affected in EPI LMS after cryoinjury. The frequency of spontaneous whole-slice contractions increased in ENDO LMS without affecting EPI LMS after injury. Cryoinjury caused an increase in foci that generates SCR in both ENDO and EPI LMS. In ENDO LMS, SCRs were more closely distributed and had reduced latencies after cryoinjury, whereas this was not affected in EPI LMS. Inhibition of CaMKII reduced the number, distribution, and latencies of SCR, as well as whole-slice contractions in ENDO LMS, but not in EPI LMS after cryoinjury. Furthermore, CaMKII inhibition did not affect the excitation–contraction coupling in cryoinjured ENDO or EPI LMS. In conclusion, we demonstrate increased arrhythmogenic susceptibility in the injured ENDO. Our findings show involvement of CaMKII and highlight the need for region-specific targeting in cardiac therapies.
Geometrically thick tori around compact objects with a quadrupole moment
Authors: Memmen Jan-Menno , Perlick Volker
Published: May 2021

We study geometrically thick perfect-fluid tori with constant specific angular momentum, so-called ‘Polish doughnuts’, orbiting deformed compact objects with a quadrupole moment. More specifically, we consider two different asymptotically flat, static and axisymmetric vacuum solutions to Einstein’s field equation with a non-zero quadrupole moment, the q-metric and the Erez–Rosen spacetime. It is our main goal to find features of Polish doughnuts in these two spacetimes which qualitatively distinguish them from Polish doughnuts in the Schwarzschild spacetime. As a main result we find that, for both metrics, there is a range of positive (Geroch–Hansen) quadrupole moments which allows for the existence of double tori. If these double tori fill their Roche lobes completely, their meridional cross-section has the shape of a fish, with the body of the fish corresponding to the outer torus and the fish-tail corresponding to the inner torus. Such double tori do not exist in the Schwarzschild spacetime.
Thin shell collapse in Kiselev geometry
Authors: Saadati R , Shojai F
Published: May 2021

We present some new aspects of Kiselev black hole and then study the null and timelike thin shell collapse in this space-time. For the latter, we show that Kiselev black hole can be matched to de Sitter core with a thin timelike dust shell to produce a non-singular space-time. It is argued that for timelike hypersurface, the equation of state parameter must be non-negative. Using Barrabès–Israel junction conditions, the equation of motion of the shell is obtained. The stability of stationary solutions of the shell is discussed and some appropriate ranges for the parameters of shell and Kiselev geometry are found for which a stable stationary black hole is constructed.
Stability of small charged anti-de Sitter black holes in the Robin boundary
Authors: Katagiri Takuya , Harada Tomohiro
Published: May 2021

We analytically and numerically study quasinormal frequencies (QNFs) of neutral and charged scalar fields in the charged anti-de Sitter (AdS) black holes and discuss the stability of the black holes in terms of the QNFs. We focus on the range of the mass squared μ
2 of the scalar fields for which the Robin boundary condition parametrized by ζ applies at the conformal infinity. We find that if the black hole of radius r
+ and charge Q is much smaller than the AdS length ℓ, the instability of the charged scalar field can be understood in terms of superradiance in the reflective boundary condition. Noting that the s-wave normal frequency in the AdS spacetime is a decreasing function of ζ, we find that if |eQ|ℓ/r
+ is greater than

(

3
+

9
+
4

μ

2

ℓ

2

)

/
2

, where e is the charge of the scalar field, the black hole is superradiantly unstable irrespectively of ζ. On the other hand, if |eQ|ℓ/r
+ is equal to or smaller than this critical value, the stability crucially depends on ζ and there appears a purely oscillating mode at the onset of the instability. We argue that as a result of the superradiant instability, the scalar field gains charge from the black hole and energy from its ambient electric field, while the black hole gives charge to the scalar field and gains energy from the scalar field but decreases its asymptotic mass parameter.
Temperature stable rare earth magnetic powder Sm-Fe-N based micro magnets with remanence enhanced by easy axis alignment and its application in MEMS actuator
Authors: Wang Huayu , Matsuura Masashi , Yamada Shusuke , Sugimoto Satoshi , Tanaka Shuji
Published: May 2021

In this paper, we report an actuator with a magnet made of novel rare earth magnetic powder Sm-Fe-N with diameter of 2 µm to 5 µm. Micro magnets were fabricated by mixing the magnetic powder with wax at temperature of 90 °C. Alignment of the easy axis process was employed to enhance the remanence of the micro magnets. A 8 T strong pulse magnetic field was utilized to magnetize the micro magnets. The properties of magnetic powder were revealed with vibrating sample magnetometer by measuring micro magnets with various magnetic powder weight loading percentages. In the best condition, the remanence reaches 0.9 T and the energy product reaches 70 kJ m−3. After that, the electromagnetic actuator was fabricated by embedding the magnetic powder in deep-reactive-ion-etched Si cavity with wax binder and parylene capping. The completed microelectromechanical system structure was mounted on a four-layer printed circuit board with embedded coils. Upon the application of a direct current for actuation, a displacement of 180 μm was obtained from a device volume of only 1.5 mm3 with a low actuation power consumption of 11.5 mW.
Quantisation of the elliptical Penning trap
Authors: Crimin Frances , Garraway Barry M , Verdú José L
Published: May 2021

We present the quantum theory of the elliptical Penning trap, i.e. the general case where the cylindrical symmetry of the electrostatic trapping potential around the trapping magnetic field axis is broken. The theory applies to both slightly and highly elliptical traps, where it is shown that the difference between the quantum states of particles in these traps corresponds to a variation of the degree of squeezing of their motional modes in the xy-plane. In a trap with tunable ellipticity, such as the Geonium Ghip planar Penning trap, it follows that control of the ellipticity via the trapping voltages enables squeezing of the quantum states of the particle. We discuss the adiabatic preparation of such squeezed states, which follows naturally from the appearance of an avoided crossing between the diabatic levels of the coupled motional states of the particle.
Gate-tunable chiral phonons in low-buckled group-IVA monolayers
Authors: Wang Hanyu , Zhou Zhichao , Chen Hao , Xia Chongqun , Zhang Lifa , Li Xiao
Published: May 2021

We investigate the electric response of chiral phonons on the low-buckled group-IVA monolayers by performing first-principles calculations. The vertical electric field breaks the degeneracy of phonon modes at high-symmetry ±K points of the phonon Brillouin zone, and the size of the phononic gap is proportional to the strength of the electric field. The gapped phonon modes at ±K possess chiralities with considerable phonon circular polarizations and discrete phonon pseudoangular momenta. The chiralities of phonons are robust against the variation of the field strength, but reversed by changing the field direction. Electric control of chiral phonons adds a new dimension to the study of chiral phonons, which has potential use in the design of phononic and valley devices.
Coarse-grained molecular dynamics simulation of cis-1,4-polyisoprene with silica nanoparticles under extreme uniaxial tension
Authors: Yuan Bin , Zeng Fanlin , Peng Chao , Wang Youshan
Published: May 2021

Coarse-grained (CG) cis-1,4-polyisoprene (PI) models with multiple silica nanoparticles (NPs) are built to study the effect of NPs and crosslinks in the uniaxial tensile simulation. The potential functions of the CG models are obtained mainly via the iterative Boltzmann inversion method. The tensile simulation results show that the grafted silica NPs and the crosslinked structure play reinforcing roles while the smooth silica NPs do the opposite, which have the similar trends with the experiment results. The differences of mechanical properties for these models are studied from different microscopic aspects, such as the network of NPs, the bond lengths, the free molecular chains, the entanglements, the stress and strain distribution and the microvoid evolution. As a result, the main reasons for the weakening of PI models with smooth silica NPs come from the weak interfacial interaction, the inhomogeneity of structural deformation and the reduction of the number of entanglements. However, if there are graft chains, the interfacial interaction can be enhanced by entangling with the matrix molecular chains. The graft chains can make it possible for the aggregated NPs to separate and can hinder the growth of microvoids at the interface. In addition, the inconsistency of the stress and strain distributions at the microscopic level is verified and the nucleation mechanism of microvoids is believed to be caused by the local violent movement of molecular chains.
Tuning critical resolved shear stress ratios for bcc-titanium Ti21S via an automated data analysis approach
Authors: Venkatraman Kaustubh , Ben Haj Slama Meriem , Taupin Vincent , Maloufi Nabila , Guitton Antoine
Published: May 2021

We introduce a novel method for automated slip trace detection and analysis based on the Hough transform algorithm and apply it to electron channeling contrast imaging micrographs. This is further augmented with an automation procedure for the determination of slip-trace crystallography in conjunction with orientation data acquired via electron backscattered diffraction. Automation is required for faster indexation of the slip traces and for more reliable statistical studies. The automation procedure was applied to different regions of interest on a β-Ti21S sample loaded in situ in tension. β-Ti21S is a bcc alloy with 48 slip systems available to accommodate plastic deformation, including all complexities associated with pencil glide. Multiple regions of interest were analyzed using the automation procedure. The acquired slip distribution statistics reveals that the majority of the slip traces belong to the {112} and {123} slip families. The deformation response of the observed regions of interest was also simulated using a full-field crystal plasticity model implemented in DAMASK, based on a phenomenological power law based constitutive formulation, incorporating all potentially active 48 slip systems. The slip system activity distribution from modelling is compared with the slip distribution statistics observed experimentally. The plasticity parameters for β-Ti21S were taken from the literature and the critically resolved shear stress (CRSS) values were adjusted to match the experimentally observed yield stress value. We begin with uniform CRSS ratios for all three potential slip system families and tune the CRSS ratios to match the slip-distribution statistics experimentally, keeping the average CRSS value the same for all cases. Thus, a method has been introduced to tune average CRSS values and ratios by considering both the macroscopic stress–strain response and the locally observed slip-distribution statistics, obtained via automated slip trace detection procedure.
Unique photoluminescence response of MoS2 quantum dots over a wide range of As (III) in aqueous media
Authors: Ansari Jamilur R , Naseh Md Farhan , Singh Neelam , Sarkar Tapan , Datta Anindya
Published: May 2021

We report the solvothermal synthesis of MoS2 based quantum dots (QDs) and the performance evaluation of bare QDs for the detection of aqueous As (III) oxidative state at room temperature and neutral pH over a vast range (0.1−1000 ppb). Concentration-dependent photoluminescence (PL) of the QDs enhances up to 50 ppb and then suppresses till 1000 ppb. It shows two distinctive slopes for enhancement and suppression. The enhancement is possibly due to the passivation of trap states or defects. The formation of tiny glassy As2S3 particles on the QD surface may be the possible reason for suppression. The pattern of optical absorption of QDs follows the similar patterns of PL. Still, it shows an enhanced absorbance in the near UV range below ≤300 nm, which increases with As (III) concentration up to 50 ppb and then decreases following the PL pattern. The MoS2 QDs were characterized by using transmission electron microscopy, x-ray diffraction, UV−Vis, and PL spectroscopy. The enhancement and suppression results were excellently fitted with the modified Stern−Volmer equation. The detection of arsenic is possible using these linear fit equations as calibration curves.
Experimental demonstration of the thermodynamic temperature unit kelvin
Authors: Alper M Patan
Published: May 2021

This study focuses on the experimental demonstration of the definition of kelvin using a triple point of water (TPW) cell and estimates the measurement uncertainty. The first part of this article is to construct the measurement setup and perform the measurements. The second stage is related with the calculation of uncertainty according to guides to the expression of uncertainty in measurement. The experiment in this study can be a practical and convenient method to show the unit as the fraction 1/273.16 of the thermodynamic temperature of the TPW, 273.16 K.
Probing P- and CP-violation in dark matter interactions
Authors: Catena Riccardo , Hagel Joakim , Yaguna Carlos E.
Published: May 2021

Discrete symmetries played a central role in elucidating the
structure of the weak interactions, and they will probably be
equally crucial regarding the interactions of the dark matter (DM)
particle — whose nature remains elusive. In this work we show that
signals in future direct detection experiments can be used to test,
in a model-independent way, for P- and CP-violation in DM-nucleus
interactions. The analysis is performed within the most general
effective theory for non-relativistic spin-0 DM-nucleus interactions
mediated by the exchange of a heavy particle. Assuming an idealised
xenon detector, we calculate the expected number of DM signal events
required to reject P and CP invariant dark matter-nucleus
interactions. For a DM mass of 30 GeV (or higher), this number lies
between about 10 and 300 DM signal events, depending on how P and CP
invariance are modeled. Future direct detection experiments,
therefore, have the potential to reveal P- and CP-violation in DM
interactions, making a decisive step toward the identification of
the DM particle.
Updated constraints on decaying cold dark matter
Authors: Nygaard Andreas , Tram Thomas , Hannestad Steen
Published: May 2021

In this paper we update the constraints on the simple
decaying cold dark matter (DCDM) model with dark radiation (DR) as
decay product. We consider two different regimes of the lifetime,
i.e. short-lived and long-lived, and use the most recent CMB data
from Planck (2018) to infer new constraints on the decay parameters
with which we compare the constraints inferred by the previous
Planck data (2015). We hereby show that the newest CMB data
constrains the fractional amount of DCDM twice as much as the
previous data in the long-lived regime, leading to our current best
2σ upper bound of f
dcdm < 2.44%. In the short-lived
regime, we get a slightly looser 2σ upper bound of
f
dcdm < 13.1% compared to the previous CMB data. If we
include Baryonic Acoustic Oscillations data from BOSS DR-12, the
constraints in both the long-lived and the short-lived regimes relax
to f
dcdm < 2.62% and f
dcdm < 1.49%, respectively. We
also investigate how this model impacts the Hubble and σ8
tensions, and we find that each of the decay regimes can slightly
relieve a different one of the tensions. The model can thus not
accommodate both tensions at once, and the improvements on each are
not significant. We furthermore improve on previous work by
thoroughly analysing the impacts of short-lived DCDM on the
radiation density and deriving a mapping between short-lived DCDM
and a correction, ΔN
eff, to the effective number of
massless neutrino species.
Additive manufacturing of polymer composites with nano-titania inclusions
Authors: Shishkovsky I V , Scherbakov V I
Published: May 2021

This study focuses on the possibility of controlling the morphology, phase-structural transformations, shape and mechanical features of a nano ceramic-polymer matrix by adding nano-titanium dioxide (TiO2) to the polymer during a selective laser sintering process. 3D parts were manufcatured from dissimilar polymers and nano-titania powder compositions with different volume ratios. Evaluations of the microstructural characteristics of the 3D samples were performed using optical and scanning electron microscopy (SEM) and x-ray analysis. SEM indicated a heterogeneous distribution of nano-titania in the polymer matrix. The x-ray patterns confirmed the presence of the original phase (TiO2) with some changes, which is useful for biomedical applications. Heating the 3D parts for approximately 30 additional minutes in the oven in the range of 50 °C–250 °C allowed us to reveal the conditions necessary for changing the porosity of the ceramic–polymer matrix, without requiring a polymer binder or titania framework fixing.
Stretchable gold nanowire-based cuff electrodes for low-voltage peripheral nerve stimulation
Authors: Lienemann Samuel , Zötterman Johan , Farnebo Simon , Tybrandt Klas
Published: May 2021

Objective. Electrical stimulation of the peripheral nervous system (PNS) can treat various diseases and disorders, including the healing process after nerve injury. A major challenge when designing electrodes for PNS stimulation is the mechanical mismatch between the nerve and the device, which can lead to non-conformal contact, tissue damage and inefficient stimulation due to current leakage. Soft and stretchable cuff electrodes promise to tackle these challenges but often have limited performance and rely on unconventional materials. The aim of this study is to develop a high performance soft and stretchable cuff electrode based on inert materials for low-voltage nerve stimulation. Approach. We developed 50 µm thick stretchable cuff electrodes based on silicone rubber, gold nanowire conductors and platinum coated nanowire electrodes. The electrode performance was characterized under strain cycling to assess the durability of the electrodes. The stimulation capability of the cuff electrodes was evaluated in an in vivo sciatic nerve rat model by measuring the electromyography response to various stimulation pulses. Main results. The stretchable cuff electrodes showed excellent stability for 50% strain cycling and one million stimulation pulses. Saturated homogeneous stimulation of the sciatic nerve was achieved at only 200 mV due to the excellent conformability of the electrodes, the low conductor resistance (0.3 Ohm sq−1), and the low electrode impedance. Significance. The developed stretchable cuff electrode combines favourable mechanical properties and good electrode performance with inert and stable materials, making it ideal for low power supply applications within bioelectronic medicine.
Performance of the CMS Zero Degree Calorimeters in pPb collisions at the LHC
Authors: Surányi O. , Al-Bataineh A. , Bowen J. , Cooper S. , Csanád M. , Hagopian V. , Ingram D. , Ferraioli C. , Grassi T. , Kellogg R. , Laird E. , Martinez G. , McBrayer W. , Mestvirishvili A. , Mignerey A. , Murray M. , Nagy M. , Onel Y. , Siklér F. , Toms M. , Veres G. , Wang Q.
Published: May 2021

The two Zero Degree Calorimeters (ZDCs) of the CMS
experiment are located at ± 140 m from the collision point and
detect neutral particles in the |η| > 8.3 pseudorapidity
region. This paper presents a study on the performance of the ZDC in
the 2016 pPb run. The response of the detectors to ultrarelativistic
neutrons is studied using in-depth Monte Carlo simulations. A method
of signal extraction based on template fits is presented, along with
a dedicated calibration procedure. A deconvolution technique for the
correction of overlapping collision events is discussed.
Sea Level Variability around the Java Sea (study Area: northern of Gresik and Surabaya) using Cryosat-2 Altimeter
Authors: Handoko Eko Yuli , Naibaho Loly Kurnia , Saptarini Dian , Yuwono
Published: May 2021

Sea level rise is one of the issues that are on the highlight today. Seawater that is in direct contact with the coastal area makes the region vulnerable to the environment. The Java Sea in Indonesia with a wide enough coverage will have many impacts on the coastal areas if there is an increase in sea level. For these observations, a sea-level anomaly (SLA) is calculated to understand sea level and its changes over time. SLA calculations use data from Cryosat-2 Satellite. Cryosat-2 is an altimetry satellite that was designed for the ice sheet observation mission and oceanography observation missions. This altimetry satellite has an excellent level of accuracy even though it does not have a microwave radiometer. This research is expected to know sea level variability of the Java Sea surface from 2011 to 2019. Obtained based on linear regression of the Cryosat-2 SLA trend, the Java Sea has decreased by 27.9746 mm at a rate of -3.55 mm/year. It is caused by the phenomenon of El-Niño Southern Oscillation (correlation coefficient of the SLA and MEI detrended indicating indicates a strong but not unidirectional correlation. The higher the MEI index, the lower the SLA value will be in the Java Sea, a vice versa, and MEI detrended, indicating a strong but not unidirectional correlation. The higher the MEI index, the lower the SLA value will be in the Java Sea, and vice versa.