bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-performance broadband photoresponse of self-powered Mg2Si/Si photodetectors
Authors: Zhu Qinghai , Ye Peng , Tang Youmei , Zhu Xiaodong , Cheng Zhiyuan , Xu Jing , Xu Mingsheng 
Published: December 2021

Abstract
Infrared optoelectronic devices are capable of operating in harsh environments with outstanding confidentiality and reliability. Nevertheless, suffering from the large band gap value, most semiconductor materials are difficult to detect infrared light signals. Here, Mg2Si/Si heterojunction photodetectors (PDs), which possess the advantages of low-cost, easy process, environmental friendliness, and compatibility with silicon CMOS technology, have been reported with a broadband spectral response as tested from 532 to 1550 nm under zero-bias. When the incident light wavelength is 808 nm, the Mg2Si/Si photodetector (PD) has a responsivity of 1.04 A W−1 and a specific detectivity of 1.51 × 1012 Jones. Furthermore, we find that the Ag nanoparticles (Ag_NPs) assembled on the Mg2Si layer can greatly improve the performance of the Mg2Si/Si PD. The responsivity and specific detectivity of Mg2Si/Si device with Ag_NPs under 808 nm illumination are 2.55 A W−1 and 2.60 × 1012 Jones, respectively. These excellent photodetection performances can be attributed to the high-quality of our grown Mg2Si material and the strong built-in electric field effect in the heterojunction, which can be further enhanced by the local surface plasmon effect and local electromagnetic field induced by Ag_NPs. Our study would provide significant guidance for the development of new self-powered infrared PDs based on silicon materials.
On the incorporation of nano TiO2 to inhibit concrete deterioration in the marine environment
Authors: Li Zhen , Dong Sufen , Ashour Ashraf , Wang Xinyue , Thakur Vijay Kumar , Han Baoguo , Shah Surendra P 
Published: December 2021

Abstract
To develop high deterioration resistance concrete for marine infrastructures, two types of nano TiO2 (NT) including anatase phase NT and silica surface-treated rutile phase NT were incorporated into concrete. The fabricated NT modified concrete was then put into the marine environment for 21 months in this study. The effects and mechanisms of two types of NT on the deterioration of concrete in the marine environment were investigated from three aspects, including seawater physical and biological as well as chemical actions on concrete with NT. Under the seawater physical action, the exposed degree of coarse sand particles on the surface of control concrete is greater than that of concrete with NT. Owing to the microorganism biodegradation property of NT, the elimination and inhibition rates of concrete with NT on microorganisms can reach up to 76.98% and 96.81%, respectively. In addition, the surface biofilm thickness of concrete can be reduced by 49.13% due to the inclusion of NT. In the aspect of seawater chemical action, NT can increase the pH value inside concrete by 0.81, increase the degree of polymerization of C–S–H gel, and improve the interfacial transition zone between cement paste and aggregate in concrete. Compared to anatase phase NT, silica surface-treated rutile phase NT is more effective in improving the deterioration resistance of concrete in the marine environment. It can be concluded that incorporating NT can inhibit the deterioration of concrete in the marine environment.
Synthesis of MnO–Sn cubes embedding in nitrogen-doped carbon nanofibers with high lithium-ion storage performance
Authors: Lu Longgang , Zhang Bin , Song Juanjuan , Gao Haiwen , Wu Zongdeng , Shen Honglong , Li Yujunwen , Lei Wu , Hao Qingli 
Published: December 2021

Abstract
In this paper, a carbon nanofiber (CNF) hybrid nanomaterial composed of MnO–Sn cubes embedding in nitrogen-doped CNF (MnO–Sn@CNF) is synthesized through electrospinning and post-thermal reduction processes. It exhibits good electrochemical lithium-ion storage performance as the anode, such as high reversible capacity, outstanding cycle performance (754 mAh g−1 at 1 A g−1 after 1000 cycles), and good rate capability (447 mAh g−1 at 5 A g−1). The excellent electrochemical properties are derived from a unique nanostructure design. MnO–Sn@CNF has a three-dimensional conductive network with a stable core–shell structure, which improves the electrical conductivity and mechanical stability of the materials. In addition, the mesopores on the surface of carbon fibers can shorten the diffusion distance of lithium ions and promote the combination of active sites of the material with lithium ions. The internal MnO and Sn form a heterostructure, which enhances the stability of the physical structure of the electrode material. This material design method provides a reference strategy for the development of high-performance lithium-ion batteries anode.
Uniform iron oxide nanoparticles reduce the required amount of polyethylenimine in the gene delivery to mesenchymal stem cells
Authors: Xu Donghang , Su Yuanqin , Xu Qianhao , Huang Ting , Chen Zhilan , Zhang Tianyuan 
Published: December 2021

Abstract
Cationic polyethylenimine (PEI) is regarded as the ‘golden standard’ of non-viral gene vectors. However, the superiority of PEI with high positive charge density also induces its major drawback of cytotoxicity, which restricts its application for an effective and safe gene delivery to stem cells. To redress this shortcoming, herein, a magnetic gene complex containing uniform iron oxide nanoparticles (UIONPs), plasmid DNA, and free PEI is prepared through electrostatic interactions for the gene delivery to bone marrow-derived mesenchymal stem cells (BM-MSCs). Results show that UIONPs dramatically promote the gene delivery to BM-MSCs using the assistance of magnetic force. In addition, decreasing the free PEI nitrogen to DNA phosphate (N/P) ratio from 10 to 6 has little adverse impact on the transgene expression levels (over 300 times than that of PEI alone at the N/P ratio of 6) and significantly reduces the cytotoxicity to BM-MSCs. Further investigations confirmed that the decrease of free PEI has little influence on the cellular uptake after applying external magnetic forces, but that the reduced positive charge density decreases the cytotoxicity. The present study demonstrates that magnetic gene delivery not only contributes to the enhanced gene expression but also helps to reduce the required amount of PEI, providing a potential strategy for an efficient and safe gene delivery to stem cells.
Printed copper-nanoplate conductor for electro-magnetic interference
Authors: Li Changning , Khuje Saurabh , Petit Donald , Huang Yulong , Sheng Aaron , An Lu , Di Luigi Massimigliano , Jalouli Alireza , Navarro Marieross , Islam Abdullah , Ren Shenqiang 
Published: December 2021

Abstract
As one of the conductive ink materials with high electric conductivity, elemental copper (Cu) based nanocrystals promise for printable electronics. Here, single crystalline Cu nanoplates were synthesized using a facile hydrothermal method. Size engineering of Cu nanoplates can be rationalized by using the LaMer model and the versatile Cu conductive ink materials are suitable for different printing technologies. The printed Cu traces show high electric conductivity of 6 MS m−1, exhibiting electro-magnetic interference shielding efficiency value of 75 dB at an average thicknesses of 11 μm. Together with flexible alumina ceramic aerogel substrates, it kept 87% conductivity at the environmental temperature of 400 °C, demonstrating the potential of Cu conductive ink for high-temperature printable electronics applications.
Asymmetric, mixed-valence molecules for spectroscopic readout of quantum-dot cellular automata
Authors: Liza Nishattasnim , Murphey Dylan , Cong Peizhong , Beggs David W , Lu Yuihui , Blair Enrique P 
Published: December 2021

Abstract
Mixed-valence compounds may provide molecular devices for an energy-efficient, low-power, general-purpose computing paradigm known as quantum-dot cellular automata (QCA). Multiple redox centers on mixed-valence molecules provide a system of coupled quantum dots. The configuration of mobile charge on a double-quantum-dot (DQD) molecule encodes a bit of classical information robust at room temperature. When arranged in non-homogeneous patterns (circuits) on a substrate, local Coulomb coupling between molecules enables information processing. While single-electron transistors and single-electron boxes could provide low-temperature solutions for reading the state of a ∼1 nm scale molecule, we propose a room-temperature read-out scheme. Here, DQD molecules are designed with slightly dissimilar quantum dots. Ab initio calculations show that the binary device states of an asymmetric molecule have distinct Raman spectra. Additionally, the dots are similar enough that mobile charge is not trapped on either dot, allowing device switching driven by the charge configuration of a neighbor molecule. A technique such as tip-enhanced Raman spectroscopy could be used to detect the state of a circuit comprised of several QCA molecules.
DIY electrodynamic trap for physics education
Authors: Rybin V , Semynin M , Rudyi S , Rozhdestvensky Yu 
Published: December 2021

Abstract
We present a simple and affordable method for making a surface electrodynamic trap for microparticles. The principles of electrodynamic trapping of charged particles are discussed and step-by-step instructions on how to make a surface trap are given. In addition to the electrodynamic trap implementation and operation process, options for its further use are proposed. The work may be of interest to physics teachers as a material for practical work, for the formation of students’ skills in performing a physical experiment.
Self-consistent modeling of microwave activated N2/CH4/H2 (and N2/H2) plasmas relevant to diamond chemical vapor deposition
Authors: Ashfold Michael N R , Mankelevich Yuri A 
Published: December 2021

Abstract
The growth rate of diamond by chemical vapor deposition (CVD) from microwave (MW) plasma activated CH4/H2 gas mixtures can be significantly enhanced by adding trace quantities of N2 to the process gas mixture. Reasons for this increase remain unclear. The present article reports new, self-consistent two-dimensional modeling of MW activated N2/H2 and N2/CH4/H2 plasmas operating at pressures and powers relevant to contemporary diamond CVD, the results of which are compared and tensioned against available experimental data. The enhanced N/C/H plasma chemical modeling reveals the very limited reactivity of N2 under typical processing conditions and the dominance of N atoms among the dilute ‘soup’ of potentially reactive N-containing species incident on the growing diamond surface. Ways in which these various N-containing species may enhance growth rates are also discussed.
Constraints on primordial black holes
Authors: Carr Bernard , Kohri Kazunori , Sendouda Yuuiti , Yokoyama Jun’ichi 
Published: December 2021

Abstract
We update the constraints on the fraction of the Universe that may have gone into primordial black holes (PBHs) over the mass range 10−5 to 1050 g. Those smaller than ∼1015 g would have evaporated by now due to Hawking radiation, so their abundance at formation is constrained by the effects of evaporated particles on big bang nucleosynthesis, the cosmic microwave background (CMB), the Galactic and extragalactic γ-ray and cosmic ray backgrounds and the possible generation of stable Planck mass relics. PBHs larger than ∼1015 g are subject to a variety of constraints associated with gravitational lensing, dynamical effects, influence on large-scale structure, accretion and gravitational waves. We discuss the constraints on both the initial collapse fraction and the current fraction of the dark matter (DM) in PBHs at each mass scale but stress that many of the constraints are associated with observational or theoretical uncertainties. We also consider indirect constraints associated with the amplitude of the primordial density fluctuations, such as second-order tensor perturbations and μ-distortions arising from the effect of acoustic reheating on the CMB, if PBHs are created from the high-σ peaks of nearly Gaussian fluctuations. Finally we discuss how the constraints are modified if the PBHs have an extended mass function, this being relevant if PBHs provide some combination of the DM, the LIGO/Virgo coalescences and the seeds for cosmic structure. Even if PBHs make a small contribution to the DM, they could play an important cosmological role and provide a unique probe of the early Universe.
A 3D multidirectional piezoelectric energy harvester using rope-driven mechanism for low frequency and ultralow intensity vibration environment
Authors: Zhang Jinhui , Lin Maoyu , Zhou Wei , Tang Lihua , Qin Lifeng 
Published: December 2021

Abstract
Though numerous piezoelectric vibration energy harvesters (PVEHs) have been designed and investigated to provide power supply for wireless sensors or wearable devices, it remains a challenge for traditional PVEHs to work effectively in an environment of low frequency, low acceleration and multidirectional vibrations. This work presents a PVEH using a low-frequency energy-capturing resonant system formed by a rolling ball in a hemispherical shell and driven by a rope. Due to the symmetry of the sphere, the ball can be excited at multiple directions in 3D space, and the piezoelectric beam can be pulled by the ball through a rope in multiple directions. Thus, the efficient multidirectional energy harvesting under low frequency (<10 Hz) and ultralow intensity (<0.1 g) vibrations could be realized. A mass-spring-damper equivalent model was built to understand the operation mechanism of the proposed PVEH. The results show that the proposed PVEH has a potential to collect energy in any direction in 3D space, and could achieve a good angle bandwidth with 360° for ϕ and 240° for β under the excitation of a = 0.04 g, f = 6.8 Hz with the acceleration

a
⃗

a
,
β
,
φ

defined in the spherical coordinate system. The developed PVEH can generate 6.5 μW under a low-intensity excitation (0.03 g), and the normalized power density can reach 22.63 μW/(cm3
g
2Hz). Moreover, the minimum start-up acceleration analysis of the proposed PVEH indicates that the PVEH can capture multidirectional energy from vibrations as low as 0.01 g. In addition, both simulation and experimental study on rope redundancy and ball mass show that they can be used to adjust the device performance easily without structure re-fabrication. Overall, this study demonstrates a new mechanism that could effectively harvest low frequency, ultralow intensity and multidirectional vibration energy.
Self-adapting model for variable stiffness magnetorheological dampers
Authors: Lian Xinyu , Deng Huaxia , Han Guanghui , Ma Mengchao , Zhong Xiang , Gao Yuexiao , Hu Rongchang 
Published: December 2021

Abstract
Variable stiffness magnetorheological fluid (MRF) dampers inherently have special nonlinear characteristics and complex structures. An accurate model describing the nonlinearity is the key for the damper to operate under variable conditions. This paper proposes a self-adapting model to characterize the variable stiffness MRF dampers through corresponding optimized algorithm. The experimental results verify the capability of the self-adapting of the model parameters. The model can describe the nonlinear characteristics of the variable stiffness MRF damper when conditions are changed. The proposed self-adaptive model improves the model accuracy which provide an approach for modeling complex dampers under variable working conditions.
Progress of ultra-high-field superconducting magnets in China
Authors: Wang Qiuliang , Liu Jianhua , Zheng Jinxing , Qin Jinggang , Ma Yanwei , Xu Qingjin , Wang Dongliang , Chen Wenge , Qu Timing , Zhang Xingyi , Jiang Donghui , Wang Yaohui , Zhou Benzhe , Qin Lang , Jin Huan , Liu Huajun , Zhai Yujia , Liu Feng 
Published: December 2021

Abstract
High magnetic fields play a critical role in the development of modern science and technology, breeding many significant scientific discoveries and boosting the generation of new technologies. In the last few years, China has undertaken a great deal of work on the application of ultra-high-field (UHF) superconducting magnet technology, such as for the Synergetic Extreme Condition User Facility in Beijing, the UHF nuclear magnetic resonance/magnetic resonance imaging, nuclear fusion energy, particle accelerator, and so on. This paper reports the research status of UHF superconducting magnets in China from different perspectives, including design options, technical features, experimental progress, opportunities, and challenges.
Non-Hermitian topological states in 2D line-graph lattices: evolving triple exceptional points on reciprocal line graphs
Authors: Liu Hang , Meng Sheng , Liu Feng 
Published: December 2021

Abstract
Non-Hermitian (NH) topological states, such as the doubly-degenerate nodes dubbed as exceptional points (EPs) in Bloch band structure of 2D lattices driven by gain and loss, have attracted much recent interest. We demonstrate theoretically that in the three-site edge-centered lattices, i.e. the so-called line-graph lattices, such as kagome lattice which is a line graph of hexagonal lattice, there exist three types of triply-degenerate EPs evolving intriguingly on another set of line graphs in the reciprocal space. A single TEP (STEP) with ±1/3 topological charge moves faithfully along the edges of reciprocal line graphs with varying gain and loss, while two STEPs merge distinctively into one unconventional orthogonal double TEP (DTEP) with ±2/3 charge at the vertices, which is characterized with two ordinary self-orthogonal eigenfunctions but one surprising ‘orthogonal’ eigenfunction. Differently, in a modified line-graph lattice with an off-edge-center site, the ordinary coalesced state of DTEPs emerges with three identical self-orthogonal eigenfunctions. Such NH states and their evolution can be generally realized in various artificial systems, such as photonic and sonic crystals, where light and sonic vortex beams with different fractional twisting can be found. Our findings shed new light on fundamental understanding of gapless topological states in NH systems in terms of creation and evolution of high-order EPs, and open up new research directions to further link line graph and flow network theory coupled with topological physics, especially under non-equilibrium gain/loss conditions.
One-BEC-species coherent oscillations with frequency controlled by a second species atom number
Authors: Morales-Molina L , Arévalo E 
Published: December 2021

AbstractControlling the tunneling of atoms of one species using a different atom species is a fundamental step in the development of a new class of atom quantum devices, where detection, motion control, and other functions over the atoms, can be achieved by exploiting the interaction between two different atomic species. Here, we theoretically study coherent oscillations of a non-self-interacting Bose–Einstein condensate (BEC) species in a triple-well potential controlled by a self-interacting species self-trapped in the central well of the potential. In this system, a blockade, due to the interspecies interaction, prevents atoms of the non-self-interacting species from populating the central well. Thus, for an initial population imbalance between the left- and right-hand wells of the non-self-interacting species, coherent BEC oscillations are induced between these two wells, resembling those of Rabi-like BEC oscillations in a double-well potential. The oscillation period is found to scale linearly with the number of self-trapped atoms as well as with the interspecies interaction strength. This behavior is corroborated by the quantum many-particle and the mean-field models of the system. We show that BEC oscillations can be described by using an effective bosonic Josephson junction with a tunneling amplitude that depends on the number of the self-trapped atoms in the central well. We also consider the effect of the self-trapped atom losses on the coherent oscillations. We show, by using quantum trajectories, that this type of losses leads to a dynamical change in the oscillation period of the non-self-interacting species, which in turn allows the number of self-trapped atoms lost from the system to be estimated.
Deformation mechanism and tensile properties of nanocrystalline CoCrCuFeNi high-entropy alloy: a molecular dynamics simulation study
Authors: Tran Anh-Son 
Published: December 2021

Abstract
For purpose of investigating the damage mechanism and tensile properties of the nanocrystalline CoCrCuFeNi high-entropy alloy, the tension experiment simulations were performed using the molecular dynamics method. The effects of the grain size, strain rate, experiment temperature, and percentage of components were considered in detail. By changing the simulated conditions of the tension experiment, the deformation and the grain growth of the nanocrystalline CoCrCuFeNi high-entropy alloy were mentioned and analyzed. The important mechanical factors such as phase transformation, stress-strain relation, shear strain, tensile strength, dislocation density, and von Mises stress were strongly influenced by changing the simulated conditions and deeply discussed.
Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn(1−x)CdxO nanoparticles at low temperatures
Authors: Ahmad Fiaz , Maqsood Asghari 
Published: December 2021

Abstract
Nanocrystalline Cd substituted ZnO nanoparticles with common formula

Z

n

1
−
x

C

d

x

O

(x = 0%, 3%, 6%, and 10%) were fabricated by a co-precipitation technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to investigate the microstructures and morphology of synthesized nanoparticles at room temperature. The outcome of the x-ray diffraction (XRD) study supports the existence of wurtzite crystal structure for ZnO, and Cd substituted ZnO samples conformed that substituted Cd ions are catching up Zn site. The morphological assessments of the fabricated nanoparticles indicated that the nature of the nanoparticles is a slightly hexagonal and mostly spherical shape with size ranges 46–55 nm. The electric impedance of the samples was measured in a wide range of frequency 100 Hz–2 MHz at different temperatures (140 K-260 K) using an LCR meter. It was observed that the dielectric constants (ε′), (

ε

″

), loss tangent (tan δ), and ac conductivity of pure and Cd substituted ZnO nanoparticles depended on frequency. The calculations of dielectric measurement showed that the parameters (ε′), (

ε

″

), loss tangent (tan δ) decreased with the increase in frequency. But the ac conductivity enhanced with the frequency, whereas the values of the above parameters increased with the temperature rise. The dielectric parameters are also found to improve with the increase in Cd concentrations. The correlated barrier-hopping (CHB) model dominated in ac conductivity. The reduction in the bandgap was also observed with Cd concentration.