bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron-induced fragmentation of water droplets: Simulation study
Authors: Suchan Jiří , Kolafa Jiří , Slavíček Petr 
Published: April 2022

The transport of free electrons in a water environment is still poorly understood. We show that additional insight can be brought about by investigating fragmentation patterns of finite-size particles upon electron impact ionization. We have developed a composite protocol aiming to simulate fragmentation of water clusters by electrons with kinetic energies in the range of up to 100 eV. The ionization events for atomistically described molecular clusters are identified by a kinetic Monte Carlo procedure. We subsequently model the fragmentation with classical molecular dynamics simulations, calibrated by non-adiabatic quantum mechanics/molecular mechanics simulations of the ionization process. We consider one-electron ionizations, energy transfer via electronic excitation events, elastic scattering, and also the autoionization events through intermolecular Coulombic decay. The simulations reveal that larger water clusters are often ionized repeatedly, which is the cause of substantial fragmentation. After losing most of its energy, low-energy electrons further contribute to fragmentation by electronic excitations. The simultaneous measurement of cluster size distribution before and after the ionization represents a sensitive measure of the energy transferred into the system by an incident electron.
STING mediates neurodegeneration and neuroinflammation in nigrostriatal α-synucleinopathy
Authors: Hinkle Jared T. , Patel Jaimin , Panicker Nikhil , Karuppagounder Senthilkumar S. , Biswas Devanik , Belingon Bonn , Chen Rong , Brahmachari Saurav , Pletnikova Olga , Troncoso Juan C. , Dawson Valina L. , Dawson Ted M. 
Published: April 2022

Significance
It is increasingly recognized that chronic neuroinflammation is causally relevant to neurodegeneration. In Parkinson’s disease (PD), α-synuclein pathology activates inflammatory signaling that disturbs parenchymal homeostasis and disrupts neuron-glia interactions. Herein, we report that the innate immune cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) DNA-sensing pathway is activated in a mouse model of α-synucleinopathy and parkinsonism, leading to type-I interferon activation that precedes the onset of neurodegeneration. Remarkably, STING-deficient mice were protected from dopaminergic neuron loss in this model. We also show that αSyn aggregates can increase STING expression and augment canonical STING activation, suggesting a possible generalized propensity for exaggerated antiviral responses in neurological states with STING elevation. Our results suggest that STING inhibition may be therapeutic in idiopathic PD and possibly other human α-synucleinopathies.
In situ optical spectroscopy of crystallization: One crystal nucleation at a time
Authors: Urquidi Oscar , Brazard Johanna , LeMessurier Natalie , Simine Lena , Adachi Takuji B. M. 
Published: April 2022

SignificanceIt is of fundamental importance to establish the microscopic picture of crystal nucleation for both academic and industrial research. Here, we report an in situ time-resolved Raman spectroscopy to study crystallization from solution, one crystal nucleation at a time. The observed dynamics of α-glycine crystallization from water without any additive supports the nonclassical nucleation pathway, where prenucleation aggregates form and convert to a crystal. By the direct comparison of Raman spectrum of the aggregates between the experiment and simulation, we propose the structure of these aggregates as linear hydrogen-bonded networks. We demonstrate the power of studying one nucleation event at a time, which can accelerate the investigation of crystal nucleation by optical spectroscopy.
Negative ion density in the ion source SPIDER in Cs free conditions
Authors: Barbisan M , Agnello R , Casati G , Pasqualotto R , Poggi C , Sartori E , Spolaore M , Serianni G 
Published: April 2022

AbstractThe SPIDER experiment, operated at the Neutral Beam Test Facility of Consorzio RFX, Padua, hosts the prototype of the H−/D−ion source for the ITER neutral beam injectors. The maximization of the ion current extracted from the source and the minimization of the amount of co-extracted electrons are among the most relevant targets to accomplish. The Cavity Ring-Down Spectroscopy diagnostic measures the negative ion density in the source close to the plasma grid (the plasma-facing grid of the ion acceleration system), so to identify the source operational parameters that maximize the amount of negative ions which can be extracted. In this study SPIDER was operated in hydrogen and deuterium in Cs-free conditions, therefore negative ions were mostly produced by reactions in the plasma volume. This work shows how the magnetic filter field and the bias currents, present in SPIDER to limit the amount of co-extracted electrons, affect the density of negative ions available for extraction. The results indicate that the magnetic filter field in front of the acceleration system should be set between about 1.6 mT, condition that maximizes the density of available negative ions, and about 3.2 mT, condition that minimizes the ratio of electron current to ion current. The negative ion density also resulted to be maximized when the plasma grid and its surrounding bias plate was positively biased against the source body with a total current in the range 0–100 A. The paper shows also how much, in Cs-free conditions, the electric fields in the acceleration system can affect the density of negative ions in the source, close to the plasma grid apertures.
Leakage current suppression and breakdown voltage enhancement in GaN-on-GaN vertical Schottky barrier diodes enabled by oxidized platinum as Schottky contact metal
Authors: Shi Zhongyu , Xiang Xueqiang , Zhang Haochen , He Qiming , Jian Guangzhong , Zhou Kai , Zhou Xuanze , Xing Chong , Xu Guangwei , Long Shibing 
Published: April 2022

Abstract
In this work, the oxidized metal PtO
x
was employed as the Schottky contact metal in the fabrication of gallium nitride (GaN)-on-GaN vertical Schottky barrier diodes (SBDs). Compared with the GaN SBD with just Pt Schottky anode, the Pt/PtO
x
/Pt-GaN SBDs exhibited a substantial reduction in reverse leakage current density

J

R

from 5.2 × 10−6 A cm−2 to 5.6 × 10−9 A cm−2 (@ −50 V) and a large rise in the breakdown voltage (

V

BD

) from 152 to 368 V, as well as maintaining the similar on-state characteristics in terms of turn-on voltage and on resistance. The temperature-dependent current–voltage characteristics of the fabricated devices further revealed that the Pt/PtO
x
/Pt-GaN SBDs possessed a higher Schottky barrier height and better high-temperature stability. Such an improvement should be attributed to the electric dipole effect in the PtO
x
layer. Moreover, the additional thin Pt layer between PtO
x
and GaN almost have no influence on the electric dipole effect of PtO
x
but can effectively protect the GaN surface from plasma damage and oxidation during the PtO
x
deposition. We believe that the proposed Pt/PtO
x
/Pt-GaN Schottky contact scheme provides a straightforward and effective strategy to develop next-generation GaN power electronic devices.
Investigation of radiation shielding by adding Al2O3 and SiO2 into the high-speed steel composites: comparative study
Authors: Gökmen Uğur , Özkan Zübeyde , Taşcı Ufuk , Bilge Ocak Sema 
Published: April 2022

Abstract
In this study, Phy-X/PSD software was utilized for searching the neutron shielding and gamma-ray shielding features of the high-speed steel composites. The effects of the Al2O3 and SiO2 contents on the irradiation properties of the T15 (0.4Si, 0.4Mn, 0.5Mo, 1.5C, 4.5Cr, 4.75Co, 5.0 V, 12.5 W) + (0%–30%) composite material were examined. The properties of the linear attenuation coefficients (LAC), half-value layer (HVL), fast neutron removal cross-sections (FNRC), mean free path (MFP), effective conductivity (C

eff
), mass attenuation coefficient (MAC), exposure buildup factors (EBF), tenth-value layer (TVL), effective atomic number (Z

eff
) were determined for the energy varying between 0.015 MeV and 15 MeV. The investigation revealed that the MAC and LAC values in the T15 composite material declined with the increase in the SiO2 or Al2O3 contents in the composite. On the other hand, the Geometric Progression (G-P) method was utilized to determine the EBFs under the penetration depth of up to 40 mfp and the same energy range. According to the results of the G-P method, the values of HVL varied from 0.01 to0.034 cm, TVL values varied from 0.01 to 0.112 cm, while FNRC values varied from 6.584 cm−1 to 8.27 cm−1, and C

eff
values varied from 1.36 × 1011 S m−1 to 3.12 × 1011 S m−1. The results revealed that the T15 high-speed steel composite provided the maximum photon shielding capacity because it showed the lowest HVL value while showing the highest Z

eff
, and MAC values. The T15 + 20% Al2O3 composite material had the highest FNRC due to its higher density. The present investigation can be considered original in terms of a few aspects. Consequently, these new shielding materials can be chosen as shielding materials against gamma radiation. In addition to contributing to several popular technologies including space technologies and nanotechnology, the present study can also contribute to nuclear technology.
A novel solar radio spectrogram encryption algorithm based on parameter variable chaotic systems and DNA dynamic encoding
Authors: Shen Yupeng , Zou Tao , Zhang Lei , Wu Zhao , Su Yanrui , Yan Fabao 
Published: April 2022

Abstract
Considering that chaotic systems are highly sensitive to parameters, we design two new parameter variable chaotic systems by constructing parameter perturbation items. These systems are constructed using the state variables of the Liu chaotic system to perturb the parameters of the Lorenz and Chen chaotic systems and are called the Lorenz-Liu chaotic system (LLCS) and Chen-Liu chaotic system (CLCS), respectively. In particular, the parameter perturbation items constructed in this study are not periodic but rather chaotic signals and change in real time. Compared with the original systems, they exhibit more complex randomness and dynamic behaviors. In the proposed cryptosystem, which considers the concept of Deoxyribonucleic Acid (DNA), the solar radio spectrogram is dynamically encoded through the LLCS, and then, the CLCS is used to scramble and diffuse the decoding matrices. In addition, the algorithm uses the 256-bit Secure Hash Algorithm (SHA-256) to generate the initial keys, which enhances the algorithm’s sensitivity to plaintext. Simulation results and security analysis show that the cryptosystem has a large key space and high key sensitivity, and can resist various attacks, such as differential attacks and chosen-plaintext attacks.
Fisher matrix for multiple tracers: the information in the cross-spectra
Authors: Abramo L. Raul , Ferri João Vitor Dinarte , Tashiro Ian Lucas 
Published: April 2022

Abstract
We derive general expressions for the multi-tracer Fisher matrix, both assuming that the cross-spectra are constrained by the auto-spectra, and also allowing for independent degrees of freedom in the cross-spectra.
We show that, just like the ratios of power spectra, the independent degrees of freedom of the cross-spectra are also not constrained by cosmic variance. Moreover, whereas the uncertainties in the ratios of power spectra decrease with the number density of the tracers as ∼ 1/√n̅, the uncertainties in the independent degrees of freedom of the cross-spectra decrease even faster, as ∼ 1/n̅. We also derive simple expressions for the optimal number of tracers in a survey.
Gravitational perturbations of the Einstein-Euler-Heisenberg black hole *
Authors: Luo Zhi , Li Jin 
Published: April 2022

Abstract
The prospect of using gravitational wave detections via the quasinormal modes (QNMs) to test modified gravity theories is exciting area of current research. Gravitational waves (GWs) emitted by a perturbed black hole (BH) will decay as a superposition of their QNMs of oscillations at the ringdown phase. In this work, we investigate the QNMs of the Einstein-Euler-Heisenberg (EEH) BH for both axial and polar gravitational perturbations. We obtain master equations with the tetrad formalism, and the quasinormal frequencies of the EEH BH are calculated in the 6th order Wentzel-Kramers-Brillöuin approximation. It is interesting to note that the QNMs of the EEH BH would differ from those of the Reissner-Nordström BH under the EH parameter, which indicates the EH parameter would affect the gravitational perturbations for the EEH BH.
GRB 190530A: From Precursor, Prompt Emission to Afterglow all Originated from Synchrotron Radiation
Authors: Liu Hui-Ya , Wang Xiang-Gao , Xin Li-Ping , Zhou Zi-Min , Chen Liang-Jun , Li Bing , Yang Yuan-Gui , Luo Qi , Li Cheng-Kui , Xiong Shao-Lin , Wang Ling-Jun , Han Xu-Hui , Song Li-Ming , Wei Jian-Yan , Liang En-Wei , Zhang Shuang-Nan 
Published: April 2022

Abstract
GRB 190 530A was jointly observed by the High Energy X-ray Telescope of the Hard X-ray Modulation Telescope (Insight-HXMT/HE) and the Ground-Based Wide-Angle Camera network (GWAC-N) with the extremely large field of view. After triggered by Insight-HXMT/HE and Fermi/GBM, we observed the optical emission of GRB 190 530A, using the 30 cm telescope of GWAC (GWAC-F30) to search and locate its position. Subsequent observation of the late afterglow of GRB 190 530A was made with the 2.16 m telescope at Xinglong Observatory. In this paper, we make a detailed exploration of the origin of GRB 190 530A. In the prompt emission, a “double-tracking” pattern is presented both for the low-energy spectral index α and the peak energy E

p
in the Band function with Insight-HXMT/HE and Fermi/GBM data; the results of GRB 190 530A are consistent with the Amati and Yonetoku correlations; the spectral lag (τ) versus energy (E) can be estimated with

τ
=
−
3.0
±
0.06
+
(
0.17
±
0.03
)
log
E

. The synchrotron radiation can account for the origin of GRB 190 530A prompt emission behaviors. The α and E

p
of the precursor are essentially the same as that of the main prompt emission, implying that they have the same origin. For the afterglow, it can be described with the external forward shock model in ISM circumburst medium. In summary, from precursor, prompt emission to afterglow of GRB 190 530A all originated from synchrotron radiation.
Estimation of Stellar Atmospheric Parameters from LAMOST DR8 Low-resolution Spectra with 20 ≤ S/N < 30
Authors: Li Xiangru , Wang Zhu , Zeng Si , Liao Caixiu , Du Bing , Kong Xiao , Li Haining 
Published: April 2022

Abstract
The accuracy of the estimated stellar atmospheric parameter evidently decreases with the decreasing of spectral signal-to-noise ratio (S/N) and there are a huge amount of this kind observations, especially in case of S/N < 30. Therefore, it is helpful to improve the parameter estimation performance for these spectra and this work studied the (T

eff
, log g, [Fe/H]) estimation problem for LAMOST DR8 low-resolution spectra with 20 ≤ S/N < 30. We proposed a data-driven method based on machine learning techniques. First, this scheme detected stellar atmospheric parameter-sensitive features from spectra by the Least Absolute Shrinkage and Selection Operator (LASSO), rejected ineffective data components and irrelevant data. Second, a Multi-layer Perceptron (MLP) method was used to estimate stellar atmospheric parameters from the LASSO features. Finally, the performance of the LASSO-MLP was evaluated by computing and analyzing the consistency between its estimation and the reference from the Apache Point Observatory Galactic Evolution Experiment high-resolution spectra. Experiments show that the Mean Absolute Errors of T

eff
, log g, [Fe/H] are reduced from the LASP (137.6 K, 0.195, 0.091 dex) to LASSO-MLP (84.32 K, 0.137, 0.063 dex), which indicate evident improvements on stellar atmospheric parameter estimation. In addition, this work estimated the stellar atmospheric parameters for 1,162,760 low-resolution spectra with 20 ≤ S/N < 30 from LAMOST DR8 using LASSO-MLP, and released the estimation catalog, learned model, experimental code, trained model, training data and test data for scientific exploration and algorithm study.
Optimal design of transcranial magnetic stimulation coil with iron core
Authors: Xu Yajie , Zhang Junhao , Xia Siping , Qiu Jian , Qiu Jing , Yang Xiaodong , Gu Weiguo , Yu Yingcong 
Published: April 2022

Abstract

Objective. Iron core coils offer a passive way to increase the induced electric field intensity during transcranial magnetic stimulation (TMS), but the influences of core position and dimensions on coil performance have not been elaborately discussed before. Approach. In this study, with the basic figure-of-eight (Fo8) and slinky coil structures, iron core coil optimization is performed with the finite element method considering core position and dimensions. A performance factor combining performance parameters, including the maximum induced electric field, stimulation depth, focus, and heat loss, is utilized to evaluate the comprehensive coil performance. Main results. According to the performance factor, both iron core coils obtain the best overall performance with a fill factor 0.4 and the two legs of the iron core close to the inner sides of the coil. Finally, three prototypes are constructed—the basic, optimized, and full-size slinky iron core coil—and magnetic field detection demonstrates a good agreement with the simulation results. Significance. The proposed systematic optimization approach for iron core coil based on Fo8 and slinky basic structure can be applied to improve TMS coil performance, reduce power requirements, and guide the design of other iron core TMS coils.
Developing a novel calcium magnesium silicate/graphene oxide incorporated silk fibroin porous scaffold with enhanced osteogenesis, angiogenesis and inhibited osteoclastogenesis
Authors: Wu Tingting , Li Binglin , Huang Wenhan , Zeng Xianli , Shi YiWan , Lin Zefeng , Lin Chengxiong , Xu Weikang , Xia Hong , Zhang Tao 
Published: April 2022

Abstract
Recently, biofunctional ions (Mg2+, Si4+, etc) and graphene derivatives are proved to be promising in stimulating bone formation. In this study, a novel inorganic/organic composite porous scaffold based on silk fibroin (SF), graphene oxide (GO), and calcium magnesium silicate (CMS) was developed for bone repair. The porous scaffolds obtained by lyophilization showed a little difference in pore structure while GO and CMS displayed a good interaction with SF matrix. The addition of CMS with good mineralization potential and sustainedly release ability of biofunctional ions (Ca2+, Mg2+ and Si4+) increased the strength of SF scaffolds a little and facilitated the osteogenic differentiation of bone mesenchymal stem cells (BMSCs) by upregulating bone formation-related genes (ALP, COL1, OC and Runx2). The further incorporation of GO in SF scaffolds enhanced the compressive strength and water retention, and also remarkably promoted the osteogenic differentiation of BMSCs. Besides, the angiogenesis of human umbilical vein endothelial cells was significantly promoted by CMS/GO/SF scaffold extract through the upregulation of angiogenesis genes (eNOs and bFGF). Moreover, the osteoclastic formation ability of RAW264.7 cells was suppressed by the released ions from CMS/GO/SF scaffold through the down-regulation of CAK, MMP9 and TRAP. The promoted osteogenesis, angiogenesis and inhibited osteoclastogenesis functions of CMS/GO/SF composite scaffold may enable it as a novel therapy for bone repair and regeneration.
A canonical Hamiltonian for open quantum systems
Authors: Hayden Patrick , Sorce Jonathan 
Published: April 2022

Abstract
If an open quantum system is initially uncorrelated from its environment, then its dynamics can be written in terms of a Lindblad-form master equation. The master equation is divided into a unitary piece, represented by an effective Hamiltonian, and a dissipative piece, represented by a hermiticity-preserving superoperator; however, the division of open system dynamics into unitary and dissipative pieces is non-unique. For finite-dimensional quantum systems, we resolve this non-uniqueness by specifying a norm on the space of dissipative superoperators and defining the canonical Hamiltonian to be the one whose dissipator is minimal. We show that the canonical Hamiltonian thus defined is equivalent to the Hamiltonian initially defined by Lindblad, and that it is uniquely specified by requiring the dissipator’s jump operators to be traceless, extending a uniqueness result known previously in the special case of Markovian master equations. For a system weakly coupled to its environment, we give a recursive formula for computing the canonical effective Hamiltonian to arbitrary orders in perturbation theory, which we can think of as a perturbative scheme for renormalizing the system’s bare Hamiltonian.
An encryption method based on computational ghost imaging with chaotic mapping and DNA encoding
Authors: Yang Zhongzhuo , Yuan Sheng , Li Jinxi , Bai Xing , Yu Zhan , Zhou Xin 
Published: April 2022

Abstract
An encryption method based on computational ghost imaging (CGI) with chaotic mapping and DNA encoding is proposed. To reduce the amount of keys in the CGI-based encryption system, the chaotic mapping algorithm is used to generate the random sequence as the speckle measurement matrix of CGI system. The measurement data of the bucket detector is subjected to block and DNA operations, which introduce the nonlinear characteristics in the encryption process. The problem of linear vulnerability of the encryption system has been greatly improved. Numerical simulation results show that, compared with the traditional CGI-based encryption method, the proposed method greatly reduces the amount of keys, increases the key space and enhances the security of the system.
Fabrication of Al/SiC composite foams with TiH2 foaming agent by laser melting deposition
Authors: Zeng Tao , Liu Ying , Wang Lu , Gao Yu , Wang Renquan 
Published: April 2022

Abstract
In this work, SiC reinforced aluminum composite foams were successfully fabricated by laser melting deposition (LMD). The microstructure, energy absorption capacity, and compressive properties of Al/SiC composite foams were investigated systematically, and the results indicated that with increasing the content of SiC nanoparticles, the porosity and average pore size of aluminum foams decreased. Compared with the pure aluminum foams, the compressive strength and energy absorption of the Al/SiC composite foams increased by 43.8% and 16.0%, from 28.5 MPa and 55.5 × 106 J m−3 to 41.0 MPa and 64.4 × 106 J m−3, respectively. The research indicates that SiC nanoparticles are effective additives to homogenize the pore size and enhance the mechanical performance of aluminum foams by the LMD method.