bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetoresistance and Kondo Effect in Nodal-Line Semimetal VAs2
*
Authors: Chen Shuijin , Lou Zhefeng , Zhou Yuxing , Chen Qin , Xu Binjie , Wu Chunxiang , Du Jianhua , Yang Jinhu , Wang Hangdong , Fang Minghu
Published: January 2021

We performed calculations of the electronic band structure and the Fermi surface, measured the longitudinal resistivity ρxx
(T,H), Hall resistivity ρxy
(T,H), and magnetic susceptibility as a function of temperature at various magnetic fields for VAs2 with a monoclinic crystal structure. The band structure calculations show that VAs2 is a nodal-line semimetal when spin-orbit coupling is ignored. The emergence of a minimum at around 11 K in ρxx
(T) measured at H = 0 demonstrates that some additional magnetic impurities (V4+, S = 1/2) exist in VAs2 single crystals, inducing Kondo scattering, evidenced by both the fitting of ρxx
(T) data and the susceptibility measurements. It is found that a large positive magnetoresistance (MR) reaching 649% at 10 K and 9 T, its nearly quadratic field dependence, and a field-induced up-turn behavior of ρxx
(T) also emerge in VAs2, although MR is not so large due to the existence of additional scattering compared with other topological nontrivial/trivial semimetals. The observed properties are attributed to a perfect charge-carrier compensation, which is evidenced by both the calculations relying on the Fermi surface and the Hall resistivity measurements. These results indicate that the compounds containing V (3d
3 4s
2) element can be as a platform for studying the influence of magnetic impurities to the topological properties.
Accurate Evaluation on the Interactions of SARS-CoV-2 with Its Receptor ACE2 and Antibodies CR3022/CB6*
Authors: Ding Hong-ming , Yin Yue-wen , Ni Song-di , Sheng Yan-jing , Ma Yu-qiang
Published: January 2021

The spread of the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become a global health crisis. The binding affinity of SARS-CoV-2 (in particular the receptor binding domain, RBD) to its receptor angiotensin converting enzyme 2 (ACE2) and the antibodies is of great importance in understanding the infectivity of COVID-19 and evaluating the candidate therapeutic for COVID-19. We propose a new method based on molecular mechanics/Poisson–Boltzmann surface area (MM/PBSA) to accurately calculate the free energy of SARS-CoV-2 RBD binding to ACE2 and antibodies. The calculated binding free energy of SARS-CoV-2 RBD to ACE2 is –13.3 kcal/mol, and that of SARS-CoV RBD to ACE2 is –11.4 kcal/mol, which agree well with the experimental results of –11.3 kcal/mol and –10.1 kcal/mol, respectively. Moreover, we take two recently reported antibodies as examples, and calculate the free energy of antibodies binding to SARS-CoV-2 RBD, which is also consistent with the experimental findings. Further, within the framework of the modified MM/PBSA, we determine the key residues and the main driving forces for the SARS-CoV-2 RBD/CB6 interaction by the computational alanine scanning method. The present study offers a computationally efficient and numerically reliable method to evaluate the free energy of SARS-CoV-2 binding to other proteins, which may stimulate the development of the therapeutics against the COVID-19 disease in real applications.
Effects of electric charges on serum protein aggregation induced by a low temperature atmospheric pressure plasma
Authors: Sakakita Hajime , Yamada Hiromasa , Shimizu Tetsuji , Fujiwara Masanori , Kato Susumu , Kim Jaeho , Ikehara Sanae , Shimizu Nobuyuki , Ikehara Yuzuru
Published: January 2021

To understand the aggregation mechanism of serum protein dispersed in the solution of distilled water induced by a low temperature atmospheric pressure plasma, we compared the relationship between the amount of aggregation and experimental condition dependencies such as gas species, gas flow rate, and the distance between the plasma device and the solution. In this experiment, pure argon, helium, and/or a mixture of helium and argon gases were used. From statistical analyses of various experimental conditions, it was found that a monotonic supply of total absolute charge in one period was important for protein aggregation. When the coefficient of variation (standard deviations/averaged total absolute charges during one period) is small, the amount of protein aggregation becomes larger. Excess or scarcity of averaged total absolute charges does not appear to relate to protein aggregation phenomena; however, the coefficient of variation strongly relates to the mechanism of protein aggregation. Therefore, a possible serum protein aggregation process by low-temperature plasma treatment was proposed in which the serum protein, which had negative charges in the solution, was locally aggregated through the trigger of charge neutralization induced by a stable charge supply, and/or positively charged aggregated protein on the solution surface attracted serum protein in the solution to the surface.
Neutron diffraction study of magnetism in van der Waals layered MnBi2n
Te3n+1
Authors: Ding Lei , Hu Chaowei , Feng Erxi , Jiang Chenyang , Kibalin Iurii A , Gukasov Arsen , Chi MiaoFang , Ni Ni , Cao Huibo
Published: January 2021

Two-dimensional van der Waals MnBi2n
Te3n+1 (n = 1, 2, 3, 4) compounds have been recently found to be intrinsic magnetic topological insulators rendering quantum anomalous Hall effect and diverse topological states. Here, we summarize and compare the crystal and magnetic structures of this family, and discuss the effects of chemical composition on their magnetism. We found that a considerable fraction of Bi occupies at the Mn sites in MnBi2n
Te3n+1 (n = 1, 2, 3, 4) while there is no detectable Mn at the non-magnetic atomic sites within the resolution of neutron diffraction experiments. The occupancy of Mn monotonically decreases with the increase of n. The polarized neutron diffraction on the representative MnBi4Te7 reveals that its magnetization density is exclusively accumulated at the Mn site, in good agreement with the results from the unpolarized neutron diffraction. The defects of Bi at the Mn site naturally explain the continuously reduced saturated magnetic moments from n = 1 to n = 4. The experimentally estimated critical exponents of all the compounds generally suggest a three-dimensional character of magnetism. Our work provides material-specified structural parameters that may be useful for band structure calculations to understand the observed topological surface states and for designing quantum magnetic materials through chemical doping.
Magneto-optical rotation of surface plasmon polaritons
Authors: Rahman Habibur , Ali Hazrat , Ahmad Iftikhar , Ud Din Rafi , Ge Guo-Qin
Published: January 2021

We investigate magneto-optical rotation (MOR) of surface plasmon polaritons (SPPs) at the interface of a metal and a four-level atomic system. The MOR of SPPs can be controlled and modified with the intensity and frequency of the applied fields. We show the birefringence enhancement of the weak probe fields propagating through the atomic medium in the presence of the static magnetic field. The external magnetic field has a vital role in the generation and control over the MOR of SPPs. The MOR completely stops when either the external magnetic field or the probe field or both are tuned to resonance. A pretty behavior of MOR of SPPs is observed for a specific set of control field frequency. The enhanced MOR of SPP has significant applications in atomic spectroscopy, optical communication, nano-photonics, optical switches, and precise measurement.
The twisted behavior of a rotating electrode atmospheric-pressure argon plasma jet
Authors: Liu J , Nie L , Xian Y , Lu X
Published: January 2021

The twisted behavior of a rotating electrode atmospheric-pressure argon plasma jet is reported and its mechanism is investigated. It is found that the plasma channel turns into a smooth pathway when about 5% of O2 or 3% of N2 are added to the main working gas, argon. Further investigation shows that the rotational frequency of the electrode, which can enhance the turbulence of the gas flow, does not affect the appearance of the plasma channel for both pure argon and argon mixed with different amounts of O2/N2. The optical emission spectra show that the emission intensities of the transitions from seven excited argon levels to two metastable states decrease dramatically when O2/N2 is added. Detailed analyses suggest that when O2/N2 is added, both the concentrations of argon in the two metastable states and their lifetimes decrease significantly, which results in a transition of the discharge channel from a turbulent pathway to a smooth pathway. In short, the metastable state of argon rather than the seed electrons plays the key role in the appearance of the plasma channel.
Fermi surfaces of the topological semimetal CaSn3 probed through de Haas van Alphen oscillations
Authors: Siddiquee K A M Hasan , Munir Riffat , Dissanayake Charuni , Hu Xinzhe , Yadav Swapnil , Takano Yasumasa , Choi Eun Sang , Le Duy , Rahman Talat S , Nakajima Yasuyuki
Published: January 2021

In the search of topological superconductors, nailing down the Fermiology of the normal state is as crucial a prerequisite as unraveling the superconducting pairing symmetry. In particular, the number of time-reversal-invariant momenta (TRIM) in the Brillouin zone enclosed by Fermi surfaces is closely linked to the topological class of time-reversal-invariant systems, and can experimentally be investigated. We report here a detailed study of de Haas van Alphen quantum oscillations in single crystals of the topological semimetal CaSn3 with torque magnetometry in high magnetic fields up to 35 T. In conjunction with density functional theory based calculations, the observed quantum oscillations frequencies indicate that the Fermi surfaces of CaSn3 enclose an odd number of TRIM, satisfying one of the proposed criteria to realize topological superconductivity. Nonzero Berry phases extracted from the magnetic oscillations also support the nontrivial topological nature of CaSn3.
Preliminary assessment of genotoxic effects induced by radiation from EAST using Vicia faba micronucleus assay
Authors: Zhang Hong , Hu Liqun , Zhong Guoqiang , Huo Zhipeng , Chen Yuqing , Zhao Sheng , Huang Liangsheng
Published: January 2021

During long-pulse deuterium plasma operations in the Experimental Advanced Superconducting Tokamak (EAST), a mixed radiation field is generated, which is mainly composed of fusion neutrons, gamma rays, and x-rays. More accurate and effective dose monitoring methods have been developed and established to determine the ionizing radiation intensity both for the stable operation of the device and for the radiation safety of personnel. As far as we know, there are few reports about the biological effects of radiation induced by fusion neutrons and γ radiation, which are of vital importance for the assessment of radiation hazards presented by fusion devices, such as EAST, to human beings and the environment. In this study, three positions in the EAST hall were selected to detect genotoxic effects induced by nuclear fusion radiation using a Vicia faba micronucleus (MN) test for the first time. The doses of neutrons and gamma rays at these places were measured by thermoluminescence dosimeters four times between June 2019 and May 2020. The radiation doses decreased as the distances from the EAST device shell gradually increased from S1 to S3. The radiation in the EAST hall resulted in a significant induction of MN in the Vicia faba root tip cells compared to a negative control, which was different from the MN frequency induced by fission neutrons, γ-rays and other kinds of radiation in previous studies. These results indicate the existence of potential genotoxic effects induced by radiation from EAST which is different from other radiation and suggest that personnel should not be permitted to enter the experimental hall during the discharge process, and that radiation protection measures should be taken during necessary maintenance to avoid radiation damage. These newly acquired results will certainly increase our knowledge about the biological effects induced by radiation from nuclear fusion and provide good data support for developing more effective environmental and personnel fusion radiation protection.
Functionalized carbonized monarch butterfly wing scales (FCBW) ornamented by β-Co(OH)2 nanoparticles: an investigation on its microwave, magnetic, and optical characteristics
Authors: Peymanfar Reza , Ghorbanian-Gezaforodi Shaghayegh
Published: January 2021

In this research, a bioinspired carbon structure was applied as a novel, unique, green, affordable, light weight, thin, and broadband microwave absorbing material. Briefly, the monarch butterfly wing scales were pyrolyzed and then CBWs were functionalized using oxidative treatments, following that they were ornamented by hexagonal β-Co(OH)2 nanoparticles to improve their microwave absorbing features based on an innovative complementary method by combining sonochemistry and hydrothermal routes. Noticeably, the polyacrylonitrile (PAN) was used as a practical medium to fabricate the microwave absorbers developing an integrated structure and augmenting the relaxation loss mechanism. Various analyses were applied to identify the prepared samples including x-ray powder diffraction, diffuse reflection spectroscopy, Fourier transform infrared, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometer, and vector network analyzer. The net-like morphology of FCBWs were fully coated by the hierarchical hexagonal β-Co(OH)2 nanoparticles. FCBW illustrated a saturation magnetization of 0.06 emu g−1 originated from its defects, distortions, dislocations, unique morphology, as well as folding, developing localized magnetic moments. Noticeably, inserting FCBWs narrow the energy bandgap of β-Co(OH)2 nanoparticles, amplifying their light absorption and polarizability, desirable for the microwave attenuation. As revealed, FCBW/β-Co(OH)2/PAN nanocomposite gained strong reflection loss (RL) of 68.41 at 9.08 GHz, while FCBW/PAN achieved broadband efficient bandwidth as wide as 7.97 GHz (RL > 10 dB) with a thickness of 2.00 mm. More significantly, β-Co(OH)2/PAN nanocomposites demonstrated salient efficient bandwidth of 3.62 GHz (RL > 20 dB) with only 2.50 mm in thickness. Noteworthy, the eye-catching microwave absorptions were obtained by only filler loading of 10 Wt%. The remarkable microwave absorbing properties of the samples were generated from their microwave absorbing mechanisms which were scrupulously dissected. More significantly, the negative imaginary parts were obtained, originated from the produced secondary fields.
Oxygen-deficient Cu doped NiFeO nanosheets hydroxide as electrode material for efficient oxygen evolution reaction and supercapacitor
Authors: Zhang Ding , Tang Xiaoning , Yang Zhaoguang , Yang Ying , Li Haipu
Published: January 2021

The development of renewable energy conversion and storage has triggered the development of electrode materials for oxygen evolution reaction (OER) and supercapacitors. Here we report a highly active Cu doped NiFe nanosheets hydroxide electrode with rich oxygen vacancies (OVs) (denoted as H-NiFeCuO/NF) prepared by in situ anodic electrodeposition on the three-dimensional macroporous nickel foam (NF) substrate followed by heat treatment with H2. The as-prepared H-NiFeCuO/NF electrode showed the initial potential of 1.44 V (versus RHE) for OER and 980 F g−1 specific capacity as supercapacitor in 1 M KOH. Further investigation suggested that the tuning of composition and structure by doping copper ions and creating OVs helped accelerate the electrochemical reactions. This practice provides an efficient approach for the fabrication of heteromultimetallic hydroxide monolithic electrode with high performance in OER or supercapacitor application.
Stability of Cu-islands formed on Si substrate via ‘dewetting’ under subsequent thermal cycling
Authors: Sonawane Dipali , Kumar Praveen
Published: January 2021

Very thin metallic films deposited on a substrate often dewet upon thermal exposure, forming discrete islands of micrometer and nanometer-sized metal particles. Herein, Cu islands on Si substrate, which were formed due to agglomeration (or ‘dewetting’) of Cu thin film at 600 °C, were exposed to thermal cycling, and the ensuing evolution in their morphology was monitored. Thermal cycling was performed between either −25 °C and 150 °C or 25 °C and 400 °C, using different heating and cooling rates. With faster heating-cooling rates, a change in the shape and size of the Cu islands was observed, whereas a slow heating-cooling rate did not induce noticeable effect on their morphology. Furthermore, the formation of new nano- and micro-sized particles, probably through the dewetting of the ultra-thin layer of Cu that was left intact during the initial agglomeration treatment, was observed during the thermal cycling performed at fast rates up to 400 °C. Finite element analysis, incorporating Anand’s viscoplasticity model, revealed the existence of high strain energy density in the vicinity of the particle-Si interface when the thermal cycling is carried at a faster ramp rate, suggesting the pivotal role of thermal stresses, in addition to the maximum temperature, in controlling the morphology of the Cu particles and the dewetting of the residual ultra-thin layer of Cu on Si.
Direct writing of silicon nanostructures using liquid-phase electron beam induced deposition of hydrosilanes
Authors: Masuda Takashi , Mori Masahiro
Published: January 2021

Solid Si (wafer) and gaseous Si (silane) are generally used as starting materials for fabricating Si devices. In this study, a liquid precursor (liquid-phase hydrosilane) for semiconducting Si, called liquid Si (liq-Si), was synthesized to establish a liquid pathway for fabricating Si. Although the liquid-to-solid Si conversion can be induced by heating at 400 °C, conversion without heating was realized herein by electron-beam (EB) irradiation. This study is the first to irradiate liq-Si with EB. Size-controllable Si nanodots, with diameters of the order of 100 nm, were directly deposited at any point by liquid-phase electron-beam-induced deposition (LP-EBID) with a beam diameter of 50 nm. This approach yielded less-contaminated deposits at the detection limit of energy-dispersive x-ray spectroscopy, as opposed to typical EBID, wherein carbon impurities up to 90% are found. The processing resolution of LP-EBID is potentially 1 nm or less. Therefore, this non-heating deposition technique realizes the direct writing of Si nanostructures and would be a powerful tool for Si nanofabrication.
Timing the opening and closure of the aortic valve using a phonocardiogram envelope: a performance test for systolic time intervals measurement
Authors: Jiménez-González Aída
Published: January 2021

Objective. This work explored the reliability of using points on the heart sounds envelope as indicators of the opening and closure of the aortic valve (AVO, AVC) to measure the pre-ejection period (PEP) and the left ventricular ejection time (LVET). Approach. 36 phonocardiograms (PCGs) from healthy subjects and cardiovascular disease subjects were denoised using single-channel independent component analysis (SCICA) and, from the Hilbert envelopes, the positions of the S1 and S2 peaks were detected (pS1, pS2). Complementarily, the positions of the local maxima of S1 and S2 (mS1, mS2) and the points surrounding pS1 and pS2 (tS1, tS2) were obtained. Finally, the reliability of these points (and the corresponding PEP and LVET intervals) was evaluated by the calculation of three error indexes (ePEP, eLVET, and score) and by comparison to reference annotations provided by echocardiography using the Bland–Altman analysis and the paired T-test. Main results. The results indicated that, from a total of 920 and 341 heartbeats in the healthy and diseased groups, respectively, the timing points given by pS1 and pS2 (or mS1 and mS2) were unlikely to substitute for the reference annotations and, thus, are unreliable for measuring the PEP and LVET intervals in the PCG. The t-points evaluation, on the other hand, indicated that tS1 was likely to substitute for AVO and was thus reliable for measuring the PEP using the PCG, with median and interquartile ranges of 0.3(8.3) ms and −0.2(7.5) ms for each group. Future work will generate an envelope with higher temporal resolution, from where tS1 and tS2 can be more accurately detected to improve the PEP and LVET measurements on a larger dataset. Significance. The statistical tests revealed that the envelope of S1 is suitable for extracting a timing point from which the pre-ejection interval can be reliably quantified, and discarded the local maximum used in other studies.
Bionic measurement of defecation in a swine model
Authors: Wang Yanmin , Sun Daming , Han Ling , Wang Mengjun
Published: January 2021

Objective. Fecobionics was used to assess pressures, orientation, bending, shape, and cross-sectional area (CSA) changes during defecation. This study aimed to evaluate the device feasibility and performance in swine. Approach. Twelve pigs had wired or wireless Fecobionics devices inserted in the rectum. The bag was distended to simulate feces in the rectum. Fecobionics data were acquired simultaneously during the whole experiment. Six pigs were euthanized immediately after the procedure for evaluation of acute injury to anorectum (acute group). The remaining pigs lived two weeks before euthanasia for evaluation of long-term tissue damage and inflammation (chronic group). Signs of discomfort were monitored. Main results. All animals tolerated the experiment well. The chronic animals showed normal behavior after the procedure. Mucosal damage, bleeding, or inflammation was not found in either group. Fecobionics was defecated 1 min 35 s–61 min 0 s (median 8 min 58 s) after insertion. The defecation lasted 0 min 20 s–4 min 25 s (median 1 min 52 s). The device was almost straight inside rectum (160°–180°) but usually bended 5°–20° during contractions. The three pressure sensors showed simultaneous and identical increase during rectal or abdominal muscle contractions, indicating the location inside rectum. During defecation, the maximum rear pressure was 114.1 ± 14.3 cmH2O whereas the front pressure gradually decreased to 0 cmH2O, indicating the front passed anus. CSA decreased from 1017.1 ± 191.0 mm2 to 530.7 ± 46.5 mm2 when the probe passed from the rectum through the anal canal. Significance. Fecobionics provides defecatory measurements under physiological conditions in pigs without inducing tissue damage.
Soft x-ray tomograms are consistent with the magneto-hydrodynamic equilibrium in the Wendelstein 7-X stellarator
Authors: Schilling Jonathan , Thomsen Henning , Brandt Christian , Kwak Sehyun , Svensson Jakob
Published: January 2021

Soft x-ray tomograms are inferred from experimental data obtained during the recent operational phases of the superconducting, optimized stellarator Wendelstein 7-X. It is shown that the reconstructed soft x-ray emission profiles of the plasma are consistent with the numerically calculated magneto-hydrodynamic equilibrium of Wendelstein 7-X. In order to obtain reliable tomograms, the full chain of electrical and geometrical influences on the x-ray observation has to be taken into account. This has been achieved by formulation and application of an extended forward model. The forward model has been verified using phantom data derived from surrogate tomograms.
Metalorganic chemical vapor deposition-grown tunnel junctions for low forward voltage InGaN light-emitting diodes: epitaxy optimization and light extraction simulation
Authors: Li Panpan , Li Hongjian , Zhang Haojun , Iza Mike , Speck James S , Nakamura Shuji , DenBaars Steven P
Published: January 2021

In this work, we demonstrate the detailed optimization of metalorganic chemical vapor deposition (MOCVD)-grown tunnel junctions (TJs) utilizing selective area growth (SAG) for regular size (0.1 mm2) and micro-size InGaN light-emitting diodes (LEDs and µLEDs). Finite-difference time-domain simulations show that the SAG apertures result in a more directional light emission of far-field radiation pattern for the SAG TJ LEDs grown on patterned sapphire substrate. Moreover, it is noted that the n-InGaN insertion layer and Si-doped concentration in the n+GaN TJs layer is essential to realize a low forward voltage (V
f) in TJs LEDs. For both 0.1 mm2 LEDs and µLEDs, the V
f is independent on the SAG aperture space varied from 3 to 8 µm when the Si-doping level in the n+GaN layer is as high as 1.7 × 1020 cm−3. The optimized TJ LEDs exhibit a comparable differential resistance of 1.0 × 10−2 Ω cm2 at 100 A cm−2 and a very small voltage penalty of 0.2–0.3 V compared to the conventional indium tin oxide contact LEDs. The low V
f penalty is caused by a higher turn on voltage, which is the smallest one among the MOCVD-grown TJs LEDs and comparable to the best molecular beam epitaxy-grown TJs LEDs.
Thermally activated polaron tunnelling conduction mechanism in Sr2MnO4 synthesized by quenching in ambient atmosphere
Authors: Nirala Gurudeo , Yadav Dharmendra , Upadhyay Shail
Published: January 2021

The oxide Sr2MnO4 was synthesized using the solid-state reaction technique. Quenching in air from 1500 °C to room temperature yielded the pure phase powder of Sr2MnO4. The purity of synthesized powder was further examined by FTIR analysis. The Rietveld refinement of XRD data confirmed the tetragonal structure and I4/mmm space group. The band gap, computed from the Tauc’s plot, was found to be 1.15 eV. The XPS analysis depicted the presence of Mn3+ and Mn4+ valence states. Measurement of the AC electrical conductivity over wide temperature (30 °C–500 °C) and frequency (0.020–2 MHz) ranges were carried out. The conduction mechanism changed from small polaron tunnelling (<270 °C) to non-overlapping large polaron tunnelling (>270 °C). The frequency versus imaginary part of the impedance (Z″) and modulus (M″) plots exhibited a change in the conduction domain with increase in temperature. This result was further verified by the Ghosh’s scaling of the conductivity spectra.
Pseudopotential form factors and electronic band structures for AlAs, AlP, BAs, BP, 3C-SiC, and cubic-GaN
Authors: Ng Jun Da , Danner Aaron
Published: January 2021

This letter introduces the pseudopotential method from first principles and demonstrates its use to determine the band structures of various semiconductors. An annotated Mathematica program, which is made available in the supplementary information, has been written to calculate fully vectorial electronic band structures in materials with diamond or zincblende crystal structures. The program could be modified for other crystal types. Making use of recently measured energy gap values for various zincblende crystals, the pseudopotential form factors of AlAs, AlP, BAs, BP, 3C-SiC, and cubic GaN, have been calculated with an iterative method and the complete electronic band structures are given. This extends the series of known form factors for semiconductors with diamond and zincblende crystal structures.
Probing Systematic Bias in Low-redshift Type Ia Supernova Measurements by Cross Analyzing Surface Brightness and Hubble Residuals
Authors: Solak H. , Kessler R. , Jones D. O.
Published: January 2021

For low-redshift (z < 0.1) SN Ia samples used in several cosmological analyses over the past decade, we probe for systematic bias by looking for correlations between surface brightness (SB) measurements and Hubble residuals (HR). For 292 SNe Ia, we measure SB at the location of the SN Ia from publicly available Pan-STARRS (PS1) images. The Hubble residuals are from two recent measurements with low-z SNe Ia that overlap the PS1 footprint: (1) the DES 3 yr cosmology analysis, with 120 overlapping low-z SNe Ia from the Harvard-Smithsonian Center for Astrophysics surveys and Carnegie Supernova Project, and (2) the PS1 single-telescope analysis, with 172 overlapping low-z SNe Ia from the Foundation Supernova Survey. This study is motivated by previous reports of anomalous inefficiencies and flux scatter for transients on bright galaxies. We compare HR distributions of the bright and faint halves of the SB distribution: the mean HR values differ by

Δ

HR

¯

= 0.031 ± 0.018, consistent with no difference at the 2σ level. We also perform a Kolmogorov–Smirnov (KS) test for the bright and faint half HR distributions, and conclude that the two distributions are statistically consistent with a KS p-value of 0.07. However, if future studies with larger data sets find

Δ

HR

¯

∼
0.03

with high significance, this difference would be a leading systematic uncertainty in measurements of the dark energy equation of state, w.
Lateral magnetic stiffness under different parameters in a high-temperature superconductor levitation system*
Authors: Yang Yong , Wu Yun-Yi
Published: January 2021

Magnetic stiffness determines the stability of a high-temperature superconductor (HTS) magnetic levitation system. The quantitative properties of the physical and geometrical parameters that affect the stiffness of HTS levitation systems should be identified for improving the stiffness by some effective methods. The magnetic stiffness is directly related to the first-order derivative of the magnetic force with respect to the corresponding displacement, which indicates that the effects of the parameters on the stiffness should be different from the relationships between the forces and the same parameters. In this paper, we study the influences of some physical and geometrical parameters, including the strength of the external magnetic field (B
0) produced by a rectangular permanent magnet (PM), critical current density (J
c), the PM-to-HTS area ratio (α), and thickness ratio (β), on the lateral stiffness by using a numerical approach under zero-field cooling (ZFC) and field cooling (FC) conditions. In the first and second passes of the PM, the lateral stiffness at most of lateral positions essentially increases with B
0 increasing and decreases with β increasing in ZFC and FC. The largest lateral stiffness at every lateral position is almost produced by the minimum value of J
c, which is obviously different from the lateral force–J
c relation. The α-dependent lateral stiffness changes with some parameters, which include the cooling conditions of the bulk HTS, lateral displacement, and movement history of the PM. These findings can provide some suggestions for improving the lateral stiffness of the HTS levitation system.
Effect of hydrogen plasma implantation on the micro-structure and magnetic properties of hcp-Co80
57Fe4Ir16 thin films*
Authors: Wang Hui , Wu Meng , Zhou Haiping , Zhang Bo , Hu Shixin , Ma Tianyong , Li Zhiwei , Qiao Liang , Wang Tao , Li Fashen
Published: January 2021

We present detailed investigations of structural and static/dynamic magnetic properties of hydrogenated hcp-Co80
57Fe4Ir16 soft magnetic thin films. Two different kinds of defects, i.e., destructive and non-destructive, were demonstrated by controlling the negative bias voltage of the hydrogenation process. Our results show that the structure and magnetic properties of our sample can be tuned by the density of the induced defects. These results provide better understanding of the hydrogenation effect and thus can be used in the future for materials processing to meet the requirements of different devices.
Resistive switching memory for high density storage and computing*
Authors: Xu Xiao-Xin , Luo Qing , Gong Tian-Cheng , Lv Hang-Bing , Liu Qi , Liu Ming
Published: January 2021

The resistive random access memory (RRAM) has stimulated a variety of promising applications including programmable analog circuit, massive data storage, neuromorphic computing, etc. These new emerging applications have huge demands on high integration density and low power consumption. The cross-point configuration or passive array, which offers the smallest footprint of cell size and feasible capability of multi-layer stacking, has received broad attention from the research community. In such array, correct operation of reading and writing on a cell relies on effective elimination of the sneaking current coming from the neighboring cells. This target requires nonlinear I–V characteristics of the memory cell, which can be realized by either adding separate selector or developing implicit build-in nonlinear cells. The performance of a passive array largely depends on the cell nonlinearity, reliability, on/off ratio, line resistance, thermal coupling, etc. This article provides a comprehensive review on the progress achieved concerning 3D RRAM integration. First, the authors start with a brief overview of the associative problems in passive array and the category of 3D architectures. Next, the state of the arts on the development of various selector devices and self-selective cells are presented. Key parameters that influence the device nonlinearity and current density are outlined according to the corresponding working principles. Then, the reliability issues in 3D array are summarized in terms of uniformity, endurance, retention, and disturbance. Subsequently, scaling issue and thermal crosstalk in 3D memory array are thoroughly discussed, and applications of 3D RRAM beyond storage, such as neuromorphic computing and CMOL circuit are discussed later. Summary and outlooks are given in the final.
X-ray absorption investigation of the site occupancies of the copper element in nominal Cu3Zn(OH)6FBr*
Authors: Wang Ruitang , Li Xiaoting , Han Xin , Lin Jiaqi , Wang Yong , Qian Tian , Ding Hong , Shi Youguo , Liu Xuerong
Published: January 2021

With Zn substitution to the three-dimensional antiferromagnetically ordered barlowite Cu4(OH)6FBr, Cu3Zn(OH)6FBr shows no magnetic phase transition down to 50 mK, and the system is suggested to be a two-dimensional kagomé quantum spin liquid [Chin. Phys. Lett.
34 077502 (2017)]. A key issue to identify such phase diagram is the exact chemical formula of the substituted compound. With Cu L-edge x-ray absorption spectrum (XAS) combined with the MultiX XAS calculations, we evaluate the Cu concentration in a nominal Cu3Zn(OH)6FBr sample. Our results show that although the Cu concentration is 2.80, close to the expected value, there is 34% residual Cu occupation in intersite layers between kagomé layers. Thus the Zn substitution of the intersite layers is not complete, and likely it intrudes the kagomé layers.
Observational constraint on the dark energy scalar field *
Authors: Zhang Ming-Jian , Li Hong
Published: January 2021

In this paper, we study three scalar fields, namely the quintessence, phantom, and tachyon fields, to explore the source of dark energy via the Gaussian processes method from the background and perturbation growth rate data. The corresponding reconstructions suggest that the dark energy should be dynamical. Moreover, the quintom field, which is a combination of the quintessence and phantom fields, is powerfully favored by the reconstruction. The mean values indicate that the potential

in the quintessence field is a double exponential function, whereas

in the phantom field is a double Gaussian function. This reconstruction can provide an important reference for the scalar field study. The two types of data employed reveal that the tachyon field is disadvantageous for describing the cosmic acceleration.
Monte-Carlo simulation of the response of bare neutron counters at the South Pole to vertical secondary particles from cosmic rays
Authors: Pagwhan A , Zingsheim A , Nuntiyakul W , Sáiz A , Mangeard P-S , Ruffolo D , Evenson P , Madsen J
Published: January 2021

Neutron monitors (NM64) are standard ground-based detectors that measure the flux of primary cosmic rays at GeV energies in space by counting secondary particles (mostly neutrons) from atmosphere cascades. The atmospheric neutrons are detected by induced nuclear fission in a gas proportional counter. In the standard design, there is a lead ring to generate evaporation neutrons that are moderated by polyethylene before being detected in the 10BF3 gas counter. By omitting the lead, so called “bare counters” respond to lower energy particles on average and can be used in conjunction with NM64 to estimate the energy spectrum of the primary cosmic rays. The specific objective of this research is to refine the understanding of the lead-free neutron monitor now installed at the South Pole using Monte-Carlo FLUKA simulations. This design uses paraffin and wood to moderate high-energy neutrons and detects them with 3He gas-filled proportional counters. Latitude surveys have shown that they have different detection efficiency from either the NM64 or polyethylene moderated bare counters, but they have never been adequately modelled. Understanding the differences quantitatively is the goal of this work. We will also report the detection efficiency of the paraffin bare for other atmospheric particles.
Preliminary indirect measurement of cosmic-ray proton spectrum using Earth’s γ-ray data from Fermi Large Area Telescope
Authors: Payoungkhamdee Patomporn
Published: January 2021

Cosmic rays (CRs) are high-energy particles, mostly protons, propagating in space. The rigidity (momentum per charge) spectrum of CRs is well described by a power law for which the spectral index is approximately 2.8 around 30 - 1000 GV. Recent measurements by PAMELA and AMS-02 indicate an abrupt change of the CR proton spectral index at about 340 GV. When CRs interact with the Earth’s upper atmosphere, γ rays can be produced and detected by space-based detectors. Here we use the Earth’s γ-ray data collected by the Fermi Large Area Telescope along with a proton-air interaction model to indirectly determine the CR proton spectral index and compare against observations by other instruments.
Traversable wormholes in massive gravity theory
Authors: Kamma Nopadhol , Wongjun Pitayuth , Nakarachinda Ratchaphat , Gumjudpai Burin
Published: January 2021

In general relativity (GR), negative pressure plays a role of wormhole tension, forbidding travelling through such a wormhole. The same problem is also found in a wormhole solution for GR with a cosmological constant. Here we consider it in the context of a modified gravitational theory so called massive gravity. Although, the massive gravity is constructed aiming in explaining the cosmic acceleration, the wormhole solution exists in this theory. There are many free parameters in wormhole solution for the de Rham-Gabadadze-Tolley (dRGT) massive gravity. The necessity of the exotic matter can be alleviated. As a result, the wormhole with less size of throat, tension as well as volume of exotic matter can be obtained.
Canonical quantization of neutral and charged static black hole as a gravitational atom
Authors: Senjaya David , Rivera Alejandro Saiz
Published: January 2021

The gravitational field is usually neglected in the calculation of atomic energy levels as its effect is much weaker than the electromagnetic field, but that is not the case for a particle orbiting a black hole. In this work, the canonical quantization of a massive and massless particles under gravitational field exerted by this tiny but very massive object—both neutral and charged—is carried out. By using this method, a very rare exact result of the particle’s quantized energy can be discovered. The presence of a very strong attractive field and also the horizon make the energy complex valued and force the corresponding wave function to be a quasi–bound state. Moreover, by taking the small scale limit, the system becomes a gravitational atom in the sense of Hydrogenic atoms energy levels and its wave function can be rediscovered. Moreover, analogous to electronic transitions, the transition of the particle in this case emits a graviton which carries a unique fingerprint of the black hole. If it can be detected, this essential information such as black hole’s mass and charge can be known.
Paper-based colorimetric sensor for potassium ion detection in urine by crown ether modified gold nanoparticles
Authors: Chitbankluai Khwanrudee , Buranachai Chittanon , Limbut Warakorn , Thavarungkul Panote
Published: January 2021

Detection and identification of potassium ion (K+) level in urine is essential for diagnosis of several deseases or for guiding treatments. We have developed a simple, rapid, low cost and naked-eye quantitative method for K+ analysis in urine using a paper-based colorimetric array test strip. The array comprised three sensing elements printed using a wax-printing technique and filled with different amounts of crown ether (4-aminodibenzo-18-crown-6) modified gold nanoparticles (AuNPs). The detection is achieved by measuring the color change (from red to violet) when AuNPs aggregated following crown ether-K+ complexation. Furthermore, the detection sensitivity could be controlled by changing the amount of the crown ether. The strip sensor array based on crown ether modified AuNPs successfully detected K+ level in the ranges of 5-1000 µM by naked eye. Thus, the developed sensor is very simple yet has a potential to be of real use in detecting K+ in real urine samples.
Finding optimal hyperparameters of feedforward neural networks for solving differential equations using a genetic algorithm
Authors: Boonthanawat C , Boonyasiriwat C
Published: January 2021

In this work, feedforward neural networks are used to solve 2D Laplace equation on rectangular domains. Optimal values of weights and biases of a network are recursively computed during the network training by minimizing a least-squares loss function using data at collocation points to approximate the true solution. The performance of the network largely depends on network architecture and model capability. In this work, an optimal set of hyperparameters is searched on various values of relative error. The genetic algorithm is used to find the optimal activation function, optimization algorithm, and weight initialization. In addition, we also searched for the optimal value of the number of hidden layers for a specific value of total parameters. Numerical results show that we can successfully obtain an optimal set of hyperparameters that is consistent across many values of relative error.
Numerical study on characteristics of sound and wake generated by flow past triangular cylinder at various incident angles
Authors: Chanthanasaro T , Boonyasiriwat C
Published: January 2021

Characteristics of sound and wake generated by flow past a triangular cylinder with Mach number 0.3 at various incident angles are studied by numerically solving the compressible Navier-Stokes equations using Open FOAM. The Reynolds number in this study is varied from 140 to 180. Vortex streets behind the cylinder are observed to have different patterns as the Reynolds number and the angle of incidence are varied. The mean lift coefficient has zero value when the cylinder is symmetric and maximum value at incident angle approximately 30°. The mean drag coefficient is observed varying when incident angle increaes. The Strouhal number observed has the value in the range of 0.15 − 0.21. Sound is generated mainly from a fluctuation in the lift and drag forces due to the shedding of vortices. The frequency of sound in far field is observed shifting when the incident angles is increased because of the different behavior of the fluctuating lift and drag forces.
Using wavelet analysis to study floods in Bangkok
Authors: Juthasirorat Narin , Anusasananan Panatcha , Suwanarat Suksan , Thangprasert Nipon
Published: January 2021

Floods in Bangkok are regular natural disasters that happen nearly every year during the monsoon season. Many streets of the city may turn into canals and seriously worsened rush-hour traffic causing many commuters to arrive late at work or school. Therefore, in this research, we will study floods in Bangkok area both seasonal flooding and occasional flooding due to the effect from La Nina cycles using the wavelet spectrum analysis and the cross wavelet method. The result from cross wavelet transform (XWT) shows that the standard precipitation index (SPI) (wet) and the oceanic index (ONI) (La Nina) have significant common power mainly in the 20-40 month band from 1967-1974 during the strong La Nina cycle. There is, however, a large area with common power outside the significance level around 32-80 month band from 1982-2002 but depicts a highly significant local correlation. The corresponding wavelet coherence spectra showed that SPI and ONI co-varied mostly in the 32-60 month band from 1966-1981 with the arrow pointing to the right and in the 64-80 month band from 1986-1994 with the arrows also pointing to the right. Although flooding is a common and annual occurrence in Bangkok, the La Nina climatic phenomenon can cause a higher than average rainfall. The intense extremely wet period during strong La Nina years was observed in 1955-1956, 1998-1999 and 2007-2008. In a La Nina years, Bangkok will receive more rain than normal years. In general, this work may contribute to the improvement of the understanding of how climate variability may impact flooding in Bangkok. Knowing of the La Nina years in advance will help the government in better planning and preparation to prevent flooding areas more than normal.
Physical properties of termite mound soil in para rubber plantation of southern border provinces
Authors: Seetapong N , Chulok S , Thongkhong V
Published: January 2021

Most farming areas in southern part of Thailand are predominated by the para rubber plantation and termite mound are generally found in almost plantation area. Termites have peculiar activities in the soil and also lead to the significant changes in the soil properties. The objective of this research was to study the physical properties of termite mound soils in para rubber plantations. The soil in the area of southern border provinces i.e. Pattani, Yala, and Narathiwas was investigated. The collected samples were divided into top, center, and base. Additionally, the soil samples were collected at the distance of 5 meters away from the mound base. It was found that the termite mound soil was comprised of silty and clay soils with high moisture and density. Most of the soil particles were sandy soil and had good water absorption coefficient. The termite mound soils were weakly acidic and by this reason the electrical conductivity was at a level that does not affect the growth and production of plants. For agriculture improvement, termite mound soils can be mixed with other soils to retain moisture, absorb water and nutrients.
Collaboration between TISTR and NIMT: An application of the pressure metrology in an air speed measurement
Authors: Pitakarnnop J , Chaiyapat U , Piromgraipak P , Luanghirun K
Published: January 2021

This paper describes a collaboration between Thailand Institute of Science and Technological Research (TISTR) and National Institute of Metrology Thailand (NIMT) in an application of a differential pressure measurement to an air speed measurement. The aim of the collaboration is to link the measurement of an air speed by a pitot static tube anemometer at TISTR to the measurement of a differential pressure at NIMT. Upon completing the project, TISTR’s pitot tube anemometer is traceable to NIMT’s force balance piston gauge. TISTR’s pitot tube anemometer in combination with its Eiffel-type wind tunnel can be employed as a calibration system for an anemometer. The result of the collaboration leads to a lower cost of maintaining TISTR’s traceability in air speed measurement.