bluuebunny/crossref_metadata_2025 huggingface dataset:
Circular photogalvanic effect of surface states in the topological insulator Bi2(Te0.23Se0.77)3 nanowires grown by chemical vapor deposition
Authors: Li Minggui , Yu Jinling , Cui Guangzhou , Chen Yonghai , Lai Yunfeng , Cheng Shuying , He Ke
Published: March 2022

Circular photogalvanic effect (CPGE) of single-crystalline ternary topological insulator Bi2(Te0.23Se0.77)3 nanowires, which are synthesized by the chemical vapor deposition, have been investigated. It is demonstrated that the distributions of the elements in the nanowires are fairly uniform, and they have high crystal quality. Compared with Bi2Se3 nanowires, the ternary Bi2(Te0.23Se0.77)3 nanowires have better responsivity to circularly polarized light. The incident angle dependence of the CPGE current indicates that the symmetry of the surface states of the nanowire belongs to C3v symmetry. The temperature dependence of the CPGE current is also investigated. As the temperature decreases from 300 to 77 K, the CPGE current first increases and then decreases, which is due to the variation of the mobility and photo-generated carrier density with temperature. Our work suggests that ternary Bi2(Te1−xSex)3 nanowires are good candidates for designing polarization-sensitive photoelectric devices.
On filamentation in the dense plasma focus
Authors: Auluck S. K. H.
Published: March 2022

Striking pictures showing filamentary structures in the plasma focus have intrigued researchers from the early days of plasma focus research. A definitive understanding of their occurrence, origin, structure, and role in plasma focus physics is still not in sight as summarized in a recent comprehensive review. This is because they are often not observed in a “standard mode” of plasma focus operation with pure deuterium, particularly in large installations, but are found in smaller experiments or those with gaseous admixtures. This has led to the suspicion that filaments are not a native feature of the plasma focus phenomenon. Recent success in observation of filaments in PF-1000 in pure deuterium operation by novel modification of the interferometer system that allows simultaneous interferometry and schlieren photography changes this situation. This Letter looks at the implications of this development in the larger context of plasma focus physics. Conceptualization of filamentation as a native feature of the traveling current distribution behind an ionizing strong shock wave is shown to be a feasible paradigm that can be formulated as a computable model for filamentation in the plasma focus.
Luminescence intensity ratio squared—A new luminescence thermometry method for enhanced sensitivity
Authors: Ćirić Aleksandar , Marciniak Łukasz , Dramićanin Miroslav D.
Published: March 2022

In response to the sensitivity limitation of ratiometric luminescence thermometers, herein we propose a novel temperature readout, which exploits two pairs of thermalized energy levels in trivalent lanthanide ion-activated phosphors, to provide significantly enhanced sensitivity. This method is called the luminescence intensity ratio squared (LIR2) method. It is a combination of the dual-excitation single emission band ratiometric (SBR) and conventional (Boltzmann) luminescence intensity ratio (LIR) techniques. The relative sensitivity of LIR2 is the sum of the sensitivities of each method, and its thermal dependence is predicted theoretically. We explain the LIR2 method in detail and identify the perspective of lanthanide-activated probes. The performance of the proposed approach was evaluated using YVO4:Eu3+ and YNbO4:Eu3+ powders and compared with those of the SBR and LIR techniques. The LIR2 method displayed significantly better thermometric performance than SBR and LIR over a wide temperature range (300–850 K).
Large-field magnetoresistance of nanometer scale nickel films grown on molybdenum disulfide
Authors: Kidd Timothy E. , Shand Paul M. , Stollenwerk Andrew , Gorgen Colin , Moua Young , Stuelke Lukas , Lukashev Pavel V.
Published: March 2022

The magnetoresistance of thin nickel films grown on molybdenum disulfide was measured in perpendicular magnetic fields as high as 90 kOe. Films with thicknesses of 20 nm provided continuous surfaces for measurement. The magnetoresistance was found to be linear with respect to the applied magnetic field with no sign of saturation. There was also no evidence of hysteresis or temperature dependence between 100 to 300 K. STM measurement showed the deposited Ni forms a continuous film of extremely small nanoclusters. However, the field dependence of magnetoresistance was found to be significantly larger than bulk Ni, which is in turn larger than Ni with nanoscale grains. We expect the unusual magnetoresistance behavior to arise from some property of the Ni-MoS2 interface.
Spin dynamics in permalloy nano-ellipses for honeycomb and square lattices
Authors: Bang Wonbae , Kaffash M. T. , Hossain M. T. , Hoffmann A. , Ketterson J. B. , Jungfleisch M. B.
Published: March 2022

We report experimental and theoretical studies of spin dynamics in lattice structures of permalloy (Ni80Fe20) nano-ellipses, with four different types of networks including honeycomb and square lattices. The lattices are patterned at the center line of the co-planar wave guide and consist of non-contacting or contacting ellipses. Micromagnetic simulations show excellent agreement with the broadband ferromagnetic resonance (FMR) experimental results. We find the existence of a spin-wave mode localized in the vertex region of the contacting nano-ellipse network. Our finding has important implications when designing an artificial spin ice (ASI) network for functional magnonics.
Ab initio study on the possible magnetic topological semimetallic state in MnMg2O4
Authors: Tomita S. , Yao D.-P. , Tsuchiura H. , Nomura K.
Published: March 2022

We study the electronic state of an inverse spinel compound MnMg2O4 based on first-principles calculations. The high-spin state is realized in Mn ions on the diamond lattice, resulting in that this material is found to be a half-metallic semimetal with the minority spin-gap about 3eV, and also with line nodes in the Brillouin zone. The intrinsic anomalous Hall conductivity (AHC) is also computed as a function of the chemical potential of the system assuming the rigid band structure, and is found to exhibit a peak structure with a maximum value of 200 S/cm at only 15 meV above the Fermi level. The relation between the large AHC and Berry curvature in the Brillouin zone is also discussed.
Gauge theory applied to chiral magnets
Authors: Ansalone Patrizio , Olivetti E. S. , Magni A. , Sola A. , Basso V.
Published: March 2022

This paper employs a non-abelian gauge theory to derive the relation between a chiral crystal structure and the bulk magnetic DMI energy term. We apply the method to the B20 chiral compounds, in which the chirality develops along the diagonals of the cubic crystal, and we derive, in this framework, the corresponding isotropic Lifshitz invariant.
Primary care consumers’ experiences and opinions of a telehealth consultation delivered via video during the COVID-19 pandemic
Authors: Manski-Nankervis Jo-Anne , Davidson Sandra , Hiscock Harriet , Hallinan Christine , Ride Jemimah , Lingam Vignesh , Holman Jessica , Baird Andrew , McKeown Emma , Sanci Lena
Published: March 2022

This study examined consumers’ experiences and opinions of a videoconference with a primary healthcare professional, and estimated the value of travel and time savings for consumers compared with face-to-face consultations. The online survey was conducted in Melbourne, Australia, between October 2020 and May 2021. The sample (n = 499) was highly educated (Bachelor degree or higher, 79%; 393/499), predominately female (70%; 347/499), mainly spoke English at home (78%; 390/499) and had a mean age of 31.8 years (s.d. 11.40). Reduced travel time (27%; 271/499) and avoiding exposure to COVID-19 (23%; 228/499) were the main reasons consumers chose a videoconference. Mental health and behavioural issues were the main reason for the consultation (38%; 241/499) and 69% (346/499) of consultations were with a general practitioner. Perceptions of the quality of care were uniformly high, with 84% (419/499) of respondents believing videoconference was equivalent to a face-to-face consultation. No association was found between reporting that telehealth was equivalent to a face-to-face consultation and education, language, health status, reason for consultation or provider type. The average time saved per consultation was 1 h and 39 min, and the average transport-related saving was A$14.29. High rates of acceptance and substantial cost savings observed in this study warrant further investigation to inform the longer-term role of videoconferences, and telehealth more broadly, in the Australian primary care system.
The structural role of bacterial eDNA in the formation of biofilm streamers
Authors: Secchi Eleonora , Savorana Giovanni , Vitale Alessandra , Eberl Leo , Stocker Roman , Rusconi Roberto
Published: March 2022

Significance

Streamers, filamentous bacterial biofilms formed in flowing systems, are ubiquitous in natural and artificial environments, where they cause clogging of devices and spreading of infections. Despite their impact, little is known about the nature and properties of streamers and their response to fluid flow. Here, we uncover the specific contribution of bacterial secreted extracellular DNA and exopolysaccharide Pel, two important components in
Pseudomonas aeruginosa
biofilms, to the formation and the mechanical properties of the streamers. We then show how this knowledge can be used to control biofilm streamer formation, both to inhibit or to promote it.
GWAS on birth year infant mortality rates provides evidence of recent natural selection
Authors: Wu Yuchang , Furuya Shiro , Wang Zihang , Nobles Jenna E. , Fletcher Jason M. , Lu Qiongshi
Published: March 2022

Significance

Quantifying natural selection in human populations is a central topic in evolutionary biology and human genetics. Current studies to identify which single-nucleotide polymorphism has undergone selection suffer from limited sample sizes and large uncertainties in the timing of selection. In this study, we advance the field by showing that a genome-wide association study (GWAS) on infant mortality rate can identify recent selection signals. Our study produces well-powered genome-wide maps for selection. It replicates two selection signals that were detected in a previous study using ancient DNA, substantially improves the resolution on the timing of selection, and provides evidence for very recent selection during World War II. It also provides fundamental insights into how to interpret GWAS results.
A conserved mechanism affecting hydride shifting and deprotonation in the synthesis of hopane triterpenes as compositions of wax in oat
Authors: Liang Miaomiao , Zhang Fan , Xu Jiaxin , Wang Xiaoning , Wu Ruibo , Xue Zheyong
Published: March 2022

Significance

Hopanoids are a group of biologically important triterpene scaffolds found in nature, but the discovery of hopane-type triterpene synthases in plants has not been reported. We discovered two types of triterpene synthases synthesizing hopanoid skeletons from monocot and dicot plants and elucidated a mechanism involving the deprotonation at different sites by site-directed mutagenesis experiments and the quantum mechanics and molecular mechanics calculation. Our results provide a genetic element for synthesizing biologically active hopane-type triterpenoids and serve as a foundation for studying the molecular mechanisms of methyl and hydride transfer in the triterpene cyclization mechanism.
Association of the load‐velocity relationship variables with 2000‐m rowing ergometer performance
Authors: Pérez‐Castilla Alejandro , Quidel‐Catrilelbún Mauricio Elías Leandro , Rodríguez‐Pérez Manuel A. , García‐Ramos Amador
Published: March 2022

This study aimed to compare the maximal mechanical variables derived from the load‐velocity (L‐V) relationship and 2000‐meter rowing ergometer performance between rowers of different age categories, and to identify the L‐V relationship variables more closely related to 2000‐meter rowing ergometer performance. Nineteen competitive rowers (15 males and four females) aged between 15 and 25 years were evaluated during the national 2000‐meter rowing ergometer competition organised by the Chilean Rowing Federation. Thereafter, the L‐V relationship variables (load‐axis intercept [L 0], velocity‐axis intercept [v 0], and area under the L‐V relationship line [A line]) were determined on separate occasions during the squat jump and prone bench pull exercises. Rowers were classified according to their chronological age for comparative purposes (under 16 years [U16] vs. over 16 years [O16]). L 0 and A line were always higher for O16 than for U16 (p ≤ 0.046; ES range = 0.99–1.79), while v 0 was generally comparable for both age categories (p ≥ 0.038; ES range = 0.07–1.03). Furthermore, the O16 revealed a greater performance (i.e. shorter total time) during the 2000‐meter rowing ergometer competition (p = 0.011; ES = −1.31). In general, significant correlations were obtained between rowing performance and the L‐V relationship variables obtained during the squat jump (r or ρ range = −0.294 to −0.922) and prone bench pull (r or ρ range = −0.322 to −0.928). These results support the L‐V relationship as a sensitive procedure to evaluate the maximal mechanical capacities of lower‐ and upper‐body muscles in competitive rowers.

Highlights

The load‐velocity relationship variables are sensitive enough to differentiate between rowers of different age categories (U16 vs. O16).

The load‐velocity variables are significantly associated with 2000‐meter rowing ergometer performance (total time).

This novel testing methodology can provide practitioners and coaches with a simpler and more precise alternative to comprehensively assess a rower's maximal neuromuscular profiles.
Novel Boron Nitride Polymorphs with Graphite-Diamond Hybrid Structure
Authors: Luo Kun , Li Baozhong , Sun Lei , Wu Yingju , Ge Yanfeng , Liu Bing , He Julong , Xu Bo , Zhao Zhisheng , Tian Yongjun
Published: March 2022

Both boron nitride (BN) and carbon (C) have sp, sp
2 and sp
3 hybridization modes, thus resulting in a variety of BN and C polymorphs with similar structures, such as hexagonal BN (hBN) and graphite, cubic BN (cBN) and diamond. Here, five types of BN polymorph structures are proposed theoretically, inspired by the graphite-diamond hybrid structures discovered in a recent experiment. These BN polymorphs with graphite-diamond hybrid structures possess excellent mechanical properties with combined high hardness and high ductility, and also exhibit various electronic properties such as semi-conductivity, semi-metallicity, and even one- and two-dimensional conductivity, differing from known insulators hBN and cBN. The simulated diffraction patterns of these BN hybrid structures could account for the unsolved diffraction patterns of intermediate products composed of so-called “compressed hBN” and diamond-like BN, caused by phase transitions in previous experiments. Thus, this work provides a theoretical basis for the presence of these types of hybrid materials during phase transitions between graphite-like and diamond-like BN polymorphs.
A Free-Volume Model for Thermal Expansion of Metallic Glass
Authors: Lu Tong , Liu Song Ling , Sun Yong Hao , Wang Wei-Hua , Pan Ming-Xiang
Published: March 2022

Many mechanical, thermal and transport behaviors of polymers and metallic glasses are interpreted by the free-volume model, whereas their applications on thermal expansion behaviors of glasses is rarely seen. Metallic glass has a range of glassy states depending on cooling rate, making their coefficients of thermal expansion vary with the glassy states. Anharmonicity in the interatomic potential is often used to explain different coefficients of thermal expansion in crystalline metals or in different metallic-glass compositions. However, it is unclear how to quantify the change of anharmonicity in the various states of metallic glass of the same composition and to connect it with coefficient of thermal expansion. In the present work, isothermal annealing is applied, and the dimensional changes are measured for La62Al14Cu11.7Ag2.3Ni5Co5 and Zr52.5Cu17.9Ni14.6Al10Ti5 metallic glasses, from which changes in density and the coefficients of thermal expansion of the specimens are both recorded. The coefficients of thermal expansion linearly decrease with densification reflecting the role of free volume in thermal expansion. Free volume is found to have not only volume but also entity with an effective coefficient of thermal expansion similar to that of gases. Therefore, the local regions containing free volume inside the metallic glass are gas-like instead of liquid-like in terms of thermal expansion behaviors.
Probing the Air Storage Failure Mechanism of Ni-Rich Layered Cathode Materials
Authors: Dong Qingyu , Yi Ruowei , Qi Jizhen , Shen Yanbin , Chen Liwei
Published: March 2022

Ni-rich layered oxide cathode materials, such as LiNi0.83Co0.12Mn0.05O2 (NCM811), exhibit high specific capacity and low cost, and become cathode material preference of high-energy-density Li-ion batteries. However, these cathode materials are not stable and will form Li-poor reconstructed layers and alkaline compounds (Li2CO3, LiOH) on the surface during the storage and processing in humid air, resulting in serious deterioration of electrochemical properties. During the past two decades, the consensus on the surface instability mechanism during humid air storage has not been reached. The main controversy focuses on the unstable octahedron mechanism and the Li/H exchange mechanism. Herein, we investigate the instability mechanism in the humid air by conducting scanning electronic microscopy, scanning transmission electron microscopy, and x-ray photoelectron spectroscopy analysis on NCM811 samples stored in designed atmospheres, etc., and realize that the surface instability of the NCM811 during storage should be mainly originated from Li/H exchange when it contacts with moisture.
A probabilistic approach to tomography and adjoint state methods, with an application to full waveform inversion in medical ultrasound
Authors: Bates Oscar , Guasch Lluis , Strong George , Caradoc Robins Thomas , Calderon-Agudo Oscar , Cueto Carlos , Cudeiro Javier , Tang Mengxing
Published: March 2022

Bayesian methods are a popular research direction for inverse problems. There are a variety of techniques available to solve Bayes’ equation, each with their own strengths and limitations. Here, we discuss stochastic variational inference (SVI), which solves Bayes’ equation using gradient-based methods. This is important for applications which are time-limited (e.g. medical tomography) or where solving the forward problem is expensive (e.g. adjoint methods). To evaluate the use of SVI in both these contexts, we apply it to ultrasound tomography of the brain using full-waveform inversion (FWI). FWI is a computationally expensive adjoint method for solving the ultrasound tomography inverse problem, and we demonstrate that SVI can be used to find a no-cost estimate of the pixel-wise variance of the sound-speed distribution using a mean-field Gaussian approximation. In other words, we show experimentally that it is possible to estimate the pixel-wise uncertainty of the sound-speed reconstruction using SVI and a common approximation which is already implicit in other types of iterative reconstruction. Uncertainty estimates have a variety of uses in adjoint methods and tomography. As an illustrative example, we focus on the use of uncertainty for image quality assessment. This application is not limiting; our variance estimator has effectively no computational cost and we expect that it will have applications in fields such as non-destructive testing or aircraft component design where uncertainties may not be routinely estimated.
Atomic insights into the influence of Bi doping on the optical properties of two-dimensional van der Waals layered InSe
Authors: Sui Fengrui , Jin Min , Zhang Yuanyuan , Hong Jin , Cheng Yan , Qi Ruijuan , Yue Fangyu , Huang Rong
Published: March 2022

As a narrow-gap semiconductor, III–VI two-dimensional (2D) van der Waals layered indium selenide (InSe) has attracted a lot of attention due to excellent physical properties. For potential optoelectronic applications, the tunability of the optical property is challenging, e.g., the modulation of optical bandgap commonly by element doping. However, the deep understanding of the influence of element doping on the microstructure and the optical properties lacks of systematic investigation. In this work, by using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, we investigate the influence of Bi doping on controlling of the microstructure and optical properties of InSe single crystal in detail. The results show that Bi doping can introduce additional stacking faults in InSe single crystal, and more importantly, the atomic spacing and lattice constant of Bi-doped InSe are changed a lot as compared to that of the undoped one. Further optical characterizations including photoluminescence and transmission spectra reveal that Bi-doping can broaden the transmission wavelength range of InSe and make its optical bandgap blue-shift, which can also be physically interpreted from the doping-induced structure change. Our work expands new ideas for the optical property modulation of 2D thin-layer materials and brings new possibilities for the development of thin-layer InSe optical devices.
Structurally modified V2O5 based extrinsic pseudocapacitor
Authors: Raha Himadri , Pradhan Debabrata , Guha Prasanta Kumar
Published: March 2022

Rapidly changing demand on energy storage systems makes it essential to redesign the device architecture and materials required to fabricate the devices. It is crucial to introduce capacitive behaviour in a conventional energy storage device (batteries) to improve the lifetime and power efficiency of the hole energy storage system. The charge storing nature of electrode material primarily depends on particle size, grain size, the electrode’s chemical structure, and effective diffusion lengths for electrolytes within the electrode. Here V2O5 based Li-ion battery electrode is transformed into a Li-ion pseudocapacitive electrode by structural modifications. The modified structures are achieved by optimizing reaction pressure to obtain larger, medium and smaller V2O5 particles (namely, V2O5-L, V2O5-M and V2O5-S). As a result, the plateau regions in galvanostatic charge–discharge plots and highly intense redox peaks in the CV plots of V2O5-L get flattened for V2O5-S. Also, the lucrative improvement in rate capabilities and stability for V2O5-S indicates induced pseudocapacitance in V2O5. Some devices are fabricated with the extrinsic pseudocapacitive material (V2O5-S), providing 4.36 mWh cm−3 volumetric energy density with 125 mW cm−3 volumetric power density. The device retains around 95% of its initial capacitance after 10k cycles and holds up to 63% after 25k stability cycles.
Unified theory of tearing mode growth from linear to Rutherford regime in the presence of local equilibrium current gradients
Authors: Huang Wenlong
Published: March 2022

Using the two-field reduced magneto-hydrodynamic (MHD) model, a new theory of tearing mode transition from linear to Rutherford regime in the presence of local equilibrium current gradient (LCG) effects is proposed. By containing the LCG term in the vorticity equation, I reproduce the modified Rutherford equation with saturation terms via a quasi-linear approach. Therefore, the LCG term in the vorticity equation is responsible for the saturation mechanism of the classical tearing mode. The unified formula of the tearing mode evolution from linear exponential growth to quasi-linear saturation is obtained if one contains the LCG and inertial terms in the vorticity equation simultaneously. Since LCG is essential for the linear growth rate of tearing mode in the marginal stable regime, the new theory is also valid when the mode close to marginality.
The effects of an LPCVD SiN
x
stack on the threshold voltage and its stability in AlGaN/GaN MIS-HEMTs
Authors: Yin Xue-Bing , Li Cheng-Guo , Zeng Qiao-Yu , Ge Xiao-Ming , Chen Zhi-Tao
Published: March 2022

In this work, we systematically studied the stoichiometry and thickness effects of low-pressure chemical vapor deposited SiN
x
bilayer stacks on the electrical properties of AlGaN/GaN heterojunction-based metal–insulator-semiconductor high electron mobility transistors. A Si-rich SiN
x
single layer reduces threshold voltage shift and hysteresis under gate stress but gives rise to high gate leakage. A near-stoichiometric SiN
x
single layer suppresses gate leakage but causes poor gate stability. A bilayer SiN
x
stack with an optimized thickness ratio improves both the gate stability and on-resistance while maintaining a low current leakage. The bilayer SiN
x
stack consisting of a 5 nm Si-rich SiN
x
interfacial layer and a 15 nm SiN
x
capping layer resulted in the lowest sheet resistance and the highest gate stability. Such enhanced gate stability is explained by the low density of trap states and the weakened electric field at the Si-rich SiN
x
/GaN interface and an extra positive charge at the bilayer interface.
Spin-wave modes of elliptical skyrmions in magnetic nanodots
Authors: Jin Chendong , Li Shuang , Zhang Hu , Wang Ruining , Wang Jianglong , Lian Ruqian , Gong Penglai , Shi Xingqiang
Published: March 2022

Magnetic skyrmions, whose shapes are ellipse due to the presence of anisotropic Dzyaloshinskii–Moriya interaction (DMI), have already been discovered in experiments recently. By using micromagnetic simulations, we discuss the ground state and the spin-wave modes of a single elliptical skyrmion in a confined nanodot. It is found that the shapes of skyrmion are stretched into a horizontal ellipse, vertical ellipse, or stripe shape under different strengths of anisotropic DMI. When elliptical skyrmions are excited by in-plane ac magnetic fields, the spin-wave mode contains a counterclockwise rotation mode at high frequencies and a clockwise (CW) rotation mode at low frequencies, and the CW mode depends on the strength of anisotropic DMI. When elliptical skyrmions are excited by out-of-plane ac magnetic fields, the spin-wave mode is split from a simple breathing mode into two complex breathing modes, including a mixed mode of CW rotation and breathing, and another anisotropic breathing mode. Our results provide an understanding of the rich spin-wave modes for skyrmions, which may contribute to the applications in magnonics.
High throughput composite sensor based on sub-wavelength dielectric grating/MDM waveguide/periodic photonic crystal
Authors: Chen Ying , Zhou Jian , Ding Zhixin , Zhang Min
Published: March 2022

Based on surface plasmon resonance (SPR) and coupled mode theory (CMT), the formation mechanism of double Fano resonances is studied in a hybrid sensing structure composed of subwavelength dielectric grating/metal-dielectric-metal (MDM) waveguide/periodic photonic crystal. Studies show that the dynamically adjustable double discrete states generated in the subwavelength dielectric grating and MDM waveguide are coupled with the continuous state formed in the periodic photonic crystal respectively to achieve double Fano resonances. And the double Fano resonances can be dynamically modulated under the angular modulation by the structure parameters. Surprisingly, the figure of merit (FOM) value of

4.00
×

10

4

is also achieved, which demonstrates the proposed structure has potential applications in sensing. In addition, the low and high refractive index sensing regions are set up. Simultaneous detection of refractive index ranges 1.00–1.29 and 3.79–4.14 is achieved. Thus, the proposed structure provides an effective reference for studying the dynamic modulation of double Fano resonances and high throughput sensors.
Can varying the gravitational constant alleviate the tensions?
Authors: Sakr Z. , Sapone D.
Published: March 2022

Constraints on the cosmological concordance model parameters
from observables at different redshifts are usually obtained using
the locally measured value of the gravitational constant GN
. Here
we relax this assumption, by considering G as a free parameter,
either constant over the redshift range or dynamical but limited to
differ from fiducial value only above a certain redshift. Using CMB
data and distance measurements from galaxy clustering BAO feature,
we constrain the cosmological parameters, along with G, through a
MCMC bayesian inference method. Furthermore, we investigate whether
the tensions on the matter fluctuation σ8
and Hubble H0
 
parameter could be alleviated by this new variable. We used
different parameterisations spanning from a constant G to a
dynamical G. In all the cases investigated in this work we found
no mechanism that alleviates the tensions when both CMB and BAO data
are used with ξg = G / GN
constrained to
1.0±0.04 (resp. ±0.01) in the constant (resp. dynamical)
case. Finally, we studied the cosmological consequences of allowing
a running of the spectral index, since the later is sensitive to a
change in G. For the two parameterisations adopted, we found no
significant changes to the previous conclusions.
Small scale effects in the observable power spectrum at large angular scales
Authors: Matthewson William L. , Durrer Ruth
Published: March 2022

In this paper we show how effects from small scales can
enter the angular-redshift power spectrum Cℓ
(z,z'). In
particular, we show that spectroscopic surveys with high redshift
resolution are already affected on large angular scales, i.e. at
low multipoles, by features from small scales. When considering
the angular power spectrum with spectroscopic redshift resolution,
it is therefore important to account for non-linearities relevant
on small scales, even at low multipoles. This may also motivate
the use of the correlation function in relatively wide redshift
bins, which is not affected by non-linearities on large scales,
instead of the angular power spectrum. The extent to which
small-scale effects become visible on large scales, which is more
relevant for bin auto-correlations than for cross-correlations, is
quantified in detail.
Optimising inflationary features the Bayesian way
Authors: Hamann Jan , Wons Julius
Published: March 2022

Modern cosmological data demand modern data analysis techniques. We introduce BayOp, a new likelihood sampling and maximisation method which is based on the Bayesian Optimisation algorithm and learns a function instead of randomly sampling from it. We apply BayOp to analyse Planck data for traces of inflationary features models with global periodic modulations of the primordial power spectrum. While we do not find any new evidence for features, we demonstrate that BayOp provides an extremely efficient way of sampling likelihoods over low-to-moderate-dimensional parameter spaces, even for very complex likelihood landscapes.
Calculations of differential momentum transfer spectra for J/ψ photoproduction in heavy-ion collisions *
Authors: Wang Pengfei , Wu Xin , Zha Wangmei , Tang Zebo
Published: March 2022

Understanding the gluonic structure in nuclei is one of the most important goals in modern nuclear physics, for which J/ψ photoproduction is suggested as a powerful tool to probe the gluon density distribution. The experimental investigation of the photoproduction process is conventionally studied in ultra-peripheral heavy-ion collisions, and has recently been extended to hadronic collisions. However, theoretical efforts in hadronic heavy-ion collisions are still lacking in the literature. In this paper, we build up a phenomenological framework to calculate the differential momentum transfer spectra for J/ψ photoproduction in hadronic heavy-ion collisions based on a vector meson dominance model. For the first time, we include the effect of internal photon radiation in the calculations, and we find that the results with internal photon radiation could describe the experimental measurements from STAR very well.
Energy Momentum Squared Gravity in Doneva-Jazadjiev anisotropic pressure model of non-rotating neutron stars
Authors: Hanifa  , Danarianto M. D. , Sulaksono A.
Published: March 2022

We implement the Doneva-Yazadjiev (DY) anisotropic model of neutron stars into Energy Momentum Squared Gravity (EMSG) theory. We have shown that the Tolmann-Oppenheimer-Volkoff (TOV) equation within this model can be expressed in the terms of effective pressure and energy density. The structure of neutron stars (NS) is then calculated by using Basic Standard Parameter equation of state with hyperons in the center. We found that the combined model is able to adjust the mass-radius relation of the NS. We also found that this model could affect boundary limit of EMSG parameter, α, in the term of stability.
Kinematics analysis of the transient Milky Way warp using RGB stars from Gaia DR2
Authors: Nurhidayat R M , Arifyanto M I , Wulandari H R T
Published: March 2022

The perturbations to the Milky Way cause the disk to have bending or breathing wave, flare, and warp. Both spatial analyses from stellar and gas show the Milky Way warp can be approached with sinusoidal function to the Galactocentric longitude. In this research, we aim to find evidence of the transient Milky Way warp using kinematics data of the Red Giant Branch (RGB) stars from Gaia Data Release 2. We only use RGB stars with positive parallaxes and small parallax uncertainties where ϖ > 0 and ϖ/σϖ
> 5, respectively. Using the linear warp model, we find the Milky Way warp starts on Rw
= 10.72 kpc, with the amplitude (γw
) of 0.39 and the Line of Node lies on ϕw
= −5.26°. Assumed the warp is a static long-lived feature on kinematics distribution, where all of the warp parameters are constant by the time, the observed vertical velocity (Vz
) is less than the expected one. The maximum Vz
is not exceeded to 12.5 km/s rather 20 km/s derived from the proposed model. It infers that the warp drive on the Milky Way is a transient feature. One of the possible reasons is the recent interaction with satellite galaxies in perturbing the outer disk of the Milky Way.
Exploring the dynamical evolution of minimoon 2020 CD3 in a circular restricted three-body problem framework
Authors: Nor M F A , Dermawan Budi
Published: March 2022

Asteroid 2020 CD3 was one of the most recently captured natural objects that became Earth’s transient satellite or minimoon. The asteroid is very likely residing in an Earth-like orbit (ELO) with 1:1 mean-motion resonance and occasionally captured by the Earth. In this study, the dynamical evolution of this object is conducted in a framework of Circular Restricted Three-Body Problem (CR3BP). Five thousand test objects are generated by distributing the orbital space with a random uniform scheme around the object’s nominal values comprising ten sigma-uncertainties of the orbital parameters and four Metonic cycles of the epoch. This numerical task has run for 1000 years with the IAS15 integrator known for its adaptive integration and high accuracy for millions of years of simulation. We found that almost all of the test particles are lying in a boundary region, hence follow chaotic and quasi-periodic trajectories and have become minimoon with an average of 15-16 times. The duration of captures of more than a year is very rare. Interestingly, there seems a preferred recapture time at ∼ 30 years. Most of them still stay in the ELO region, although a few have either been hit the Earth or expelled into vast space.
Preliminary results on spectral line survey of Uranus at the millimeter/sub-millimeter wavelength using ALMA data
Authors: Mumtahana Farahhati , Hidayat Taufiq
Published: March 2022

Previous studies and spectroscopy observations concluded that Uranus has the fewest spectral line features among other giant planets. It is challenging yet very possible to conduct the line survey with the abundance of available Uranus observation data, particularly in millimeter/sub-millimeter. As a sensitive radio interferometer, Atacama Large Millimeter/submillimeter Array (ALMA) frequently observes Uranus from wide viewing windows and the narrow spectral resolution which is very suitable for spectral survey study. In this paper, we report the preliminary results of Uranus’ spectral line survey over various ranges of ALMA spectral windows at bands 3 to 9, taken from 2012 – 2018. With CASA data processing tools, the survey results from 451 spectral windows (spw), 216 line candidates from 98 spw were suspected as the first step to examine molecule’s existence in Uranus. Although most of them had SNR below 3, some prominent spectral line features were detected tentatively such as the line profiles at the frequency of carbon monoxide (CO) and methanol (CH3OH). The inconsistent results on CO confirmed the previous theory that this molecule might be originally from external. Although this CO detection is an important finding as it might be the first time to be discovered in Uranus from ALMA, to declare as a real detection, it is necessary to confirm with more observations and correction with some relevant factors.
Fluctuation of Satellite Charging in the Low Earth Orbit Regime due to Interaction with Ionospheric Plasma
Authors: Ahmad Nizam
Published: March 2022

Low Earth-orbiting satellites will always interact with the ionospheric plasma, leading to disruption of satellite operations, depending on the impact of the interaction. Under normal circumstances (without interference), the magnitude of the fluctuation in satellite charging is less than 5V (negative). Any disturbance from charged particles will cause the satellite to experience a more drastic voltage drop of the order of a few hundred volts (negative). The identification of fluctuations in satellite charging is carried out by reviewing the space conditions around the satellite, characterized by several parameters such as density, energy, and plasma temperature, as well as the saturation density of the satellite. To strengthen the analysis, this study deepens the flux changes with an energy of the order of MeV along the satellite orbit. The results of the study show that several low-earth orbit satellites experience a fairly high saturation density, which is correlated with fluctuations in electron flux in some regions traversed by the satellite, such as the polar and the SAA regions. The results confirm that the two regions could be a danger zone for both polar and equatorial satellites.
Development of 24 hours Dst index prediction from solar wind data and IMF Bz using NARX
Authors: Nuraeni F , Ruhimat M , Aris M A , Ratnasari E A , Purnomo C
Published: March 2022

Disturbance Storm Time (Dst) index is an index which measured the decrease in the horizontal component of the Earth’s magnetic field near the magnetic equator due to increases in the magnetospheric ring current. The index shows the strength and duration of a geomagnetic storm. The geomagnetic storms themselves could harm technological systems on earth. Dst index prediction is needed as an effort to mitigate the impact of geomagnetic storms. This paper described a 24 hours Dst index prediction using a nonlinear autoregressive exogenous (NARX) method. Solar wind parameters and interplanetary magnetic field (IMF) Bz has been used as exogenous input for the model. By using 39 geomagnetic storms data during 1997 to 2000 as training data and 7 geomagnetic storms data during 2000 to 2001 as testing data that have not been used in the training, the correlation between target and ouput was 0.97. The model than being used to predict Dst index for operational purposes and obtained the RMSE from 1 August to 31 October 2021 was ‘∼5 – 20 nT during quiet days and ∼18 – 45 nT during disturb days.
Automated georeferencing of Diwata-2 multispectral imagery using feature matching
Authors: Brotoisworo P , Aranas RK , Felix MJ
Published: March 2022

The Diwata-2 microsatellite is a 56 kg optical microsatellite that features different optical sensors such as the medium resolution Spaceborne Multispectral Sensor (SMI) and a high-resolution sensor called High Precision Telescope (HPT). This research aims to develop an automated georeferencing workflow for coregistered multiband HPT and SMI imagery with a GSD of 5 meters and 127 meters respectively. Georeferencing is done using a mixture of FAST and SIFT feature matching algorithms where HPT imagery used SIFT descriptors and detectors and SMI used FAST detectors and SIFT descriptors. The research used freely available Landsat- 8 imagery which was processed into cloud-free mosaics as reference data. Accuracy assessment is automated using AROSICS software which performs geometric correction and calculates the RMSE of local shifts based on image tie points which are automatically generated using the Diwata image as secondary image and Landsat-8 as reference image. Output of the feature matching algorithms has achieved high accuracy with an average RMSE value of 2.55 meters for HPT imagery and 65.96 meters for SMI imagery. Both RMSE values are close to half the GSD of both sensors which indicate sub-pixel precision. Future research for this method includes additional method for keypoint filtering to further increase the accuracy of the feature matching.
Correlating between global solar radiation and greenhouse gases over Nigeria
Authors: Ibeh G F , Sombo T , Edebeatu Chinedu Callistus , Azi A O , Ogonna C A , Ekpe J E , Akande P I
Published: March 2022

The need to study the variations of climate change in Nigeria becomes necessary at a time the universe and Nigerians, in particular are passing through challenges due to climate change as a result of emissions. The atmospheric gases have a greater transparency for incoming solar radiation, while the outgoing are trapped and re-emitted back to the Earth. This study correlated between global solar radiation and greenhouse gases over Nigeria using neural network. The results showed that positive correlations exist between solar radiations: CO2 and CH4 respectively, while exhibiting negative correlations with tropospheric ozone and water vapour. Consequently, an increase in 0.1017, 0.1350 units of CO2 and CH4, respectively could enhance the trapping and transmission of solar radiation in the atmosphere, while an increase of 1.1234 and 0.1530 units of tropospheric ozone and water vapour could cause absorption of solar radiation. The trapped energy is re-radiated back to the Earth, this warms up the atmosphere and the surface of the Earth resulting to global warming. Coefficient of determination revealed that 18%, 30%, 20%, and 29%, of the variances of solar radiation being studied is explained by the variance of the water vapour, tropospheric O3, CO2, and CH4, respectively.
Random sequential adsorption of rounded rectangles, isosceles and right triangles
Authors: Cieśla Michał , Kozubek Konrad , Kubala Piotr
Published: March 2022

We studied random sequential adsorption (RSA) of three classes of polygons with rounded corners: rectangles, isosceles triangles, and orthogonal triangles. Using the algorithm that enables the generation of strictly saturated RSA packing, we systematically determined the mean saturated packing fraction for RSA configurations built by these shapes. The main aim was to find the figure that forms the densest random configuration. Although for rounded rectangles the packing fractions were lower than for discorectangles, the densities reached for some rounded isosceles and right triangles exceeded the highest known two-dimensional packing fraction for configurations built of unoriented monodisperse objects. The microstructural properties of several packings were discussed in terms of the two-point density autocorrelation function.
Study of bladder release agent formulas and methods to evaluate their efficiencies by using reciprocating tribometer
Authors: Tanboriphan N , Teeraprawatekul B , Mahathanabodee S , Jangchud I
Published: March 2022

Bladder is one of the most important components in tire manufacturing process. In tire industry, methods to prolong bladder service-life and good bladder coatings for non-stick surface has been acquired. Bladder coated with good release agents can help reducing nonconforming products and increasing production efficiency. In this work, semi-permanent release agent formulas were studied. A new method to evaluate release agent efficiency by using a reciprocating tribometer were also carried out. Polydimethyl siloxane (PDMS) release agent formulas were developed with and without polymethyl hydrogen siloxane (PMHS). Effects of metal salt cure catalyst were also studied. In this work, method of release efficiency test was developed by using a reciprocating tribometer according to ASTM G133-05. It can be used to determine coefficient of friction of the coated surface and durability of the coatings. Coating durability test was also confirmed by repeating compression molding test to determine the number of release cycles. It was found that film durability was improved by adding the metal salt catalyst and PMHS. As the PMHS loading was increased, film endurance was improved to an optimum loading. Friction coefficient of the coatings could be related to the mold release ability and durability of the release agents. The technique can be used to estimate the service-life of the coated bladders. It can be used as a guideline for development of mold release agents in tire manufacturing industry.
Influence of nanofiller types on morphology and mechanical properties of natural rubber nanocomposites
Authors: Wongvasana B , Masa A , Saito H , Sakai T , Lopattananon N
Published: March 2022

Natural rubber (NR) nanocomposite containing different types of filler, i.e., nanoclay (clay) and cellulose nanofiber (CNF) were prepared in this study. The masterbatches of NR with 5 parts per hundred parts of rubber of nanofiller were firstly prepared by using the latex mixing method, followed by compounding on two roll mill and compression molding to obtain NR nanocomposite specimens. The unfilled NR sample was also prepared for comparison. Morphological properties of NR nanocomposites were investigated by using transmission electron microscopy, while the mechanical and dynamic properties were studied by using a universal tensile testing machine and dynamic mechanical analyzer (DMA). It was found that the clay with platelet morphology was uniformLy dispersed, while the long and flexible CNFs were aggregated and poorly dispersed. The greater improvement of modulus at various strains was achieved from CNF filled NR nanocomposites, while the highest tensile strength was obtained from the clay filled nanocomposite. As compared to the clay containing nanocomposite, the addition of CNF markedly decreased the tensile strength and elongation at break of the NR due to poor dispersion of CNF. However, a significant improvement in mechanical properties at low strain was obtained when the CNF was used as filler due to high degree of fiber entanglement, as suggested by DMA observation.
Effect of arecoline, aqueous and methanolic areca nut extracts on rumen fluke
Authors: Puyathorn N , Sukonpan C , Toungsuwan P , Narakornwit W , Phaechamud T
Published: March 2022

Paramphistomosis is a parasitic disease that causes a reduction of livestock production and economic losses worldwide. In order to avoid side effect and chemical residue from usage of chemical drugs, medicinal plant is an alternative drug for treatment. Areaca nut (Areaca catechu) which one of the domestic plants in Southeast Asia had antihelmintic activity. In this study, arecoline, aqueous and methanolic extracts of areca nut prepared in solutions were tested for antihelmintic activity against rumen flukes (Paramphistomum sp.). The parasites were incubated in a culture media (RPMI-1640, pH 8) at 39°C in a carbon dioxide-incubator containing 0.01, 0.1 and 1 mg/mL of the tested compounds for 15, 30 min, 1 h and 24 h. The results showed that the methanolic and aqueous crude extracts from seeds of Areaca catechu and arecoline HBr at concentration of 1 mg/mL solutions could destroy the tegument (surface membrane) of the flukes and killed them all at initial time. Thus, these areca nut extracts exhibited the potential alternative medicine with antihelmintic activity against rumen flukes.