bluuebunny/crossref_metadata_2025 huggingface dataset:
Reticulon-like REEP4 at the inner nuclear membrane promotes nuclear pore complex formation
Authors: Golchoubian Banafsheh , Brunner Andreas , Bragulat-Teixidor Helena , Neuner Annett , Akarlar Busra A. , Ozlu Nurhan , Schlaitz Anne-Lore
Published: December 2021

Nuclear pore complexes (NPCs) are channels within the nuclear envelope that mediate nucleocytoplasmic transport. NPCs form within the closed nuclear envelope during interphase or assemble concomitantly with nuclear envelope reformation in late stages of mitosis. Both interphase and mitotic NPC biogenesis require coordination of protein complex assembly and membrane deformation. During early stages of mitotic NPC assembly, a seed for new NPCs is established on chromatin, yet the factors connecting the NPC seed to the membrane of the forming nuclear envelope are unknown. Here, we report that the reticulon homology domain protein REEP4 not only localizes to high-curvature membrane of the cytoplasmic endoplasmic reticulum but is also recruited to the inner nuclear membrane by the NPC biogenesis factor ELYS. This ELYS-recruited pool of REEP4 promotes NPC assembly and appears to be particularly important for NPC formation during mitosis. These findings suggest a role for REEP4 in coordinating nuclear envelope reformation with mitotic NPC biogenesis.
Revisiting cosmologies in teleparallelism
Authors: D’Ambrosio Fabio , Heisenberg Lavinia , Kuhn Simon
Published: December 2021

We discuss the most general field equations for cosmological spacetimes for theories of gravity based on non-linear extensions of the non-metricity scalar and the torsion scalar. Our approach is based on a systematic symmetry-reduction of the metric-affine geometry which underlies these theories. While for the simplest conceivable case the connection disappears from the field equations and one obtains the Friedmann equations of general relativity, we show that inf(Q)cosmology the connection generically modifies the metric field equations and that some of the connection components become dynamical. We show thatf(Q)cosmology contains the exact general relativity solutions and also exact solutions which go beyond. Inf(T)cosmology, however, the connection is completely fixed and not dynamical.
Supersymmetry enhancement of heterotic horizons
Authors: Farotti D , Gutowski J
Published: December 2021

The supersymmetry of near-horizon geometries in heterotic supergravity is considered. A necessary and sufficient condition for a solution to preserve more than the minimal N = 2 supersymmetry is obtained. A supersymmetric near-horizon solution is constructed which is a U(1) fibration of AdS
3 over a particular Aloff–Wallach space. It is proven that this solution preserves the conditions required for N = 2 supersymmetry, but does not satisfy the necessary condition required for further supersymmetry enhancement. Hence, there exist supersymmetric near-horizon heterotic solutions preserving exactly N = 2 supersymmetry.
On stochastic Kaczmarz type methods for solving large scale systems of ill-posed equations
Authors: Rabelo J C , Saporito Y F , Leitão A
Published: December 2021

In this article we investigate a family of stochastic gradient type methods for solving systems of linear ill-posed equations. The method under consideration is a stochastic version of the projective Landweber–Kaczmarz method in Leitão and Svaiter (2016 Inverse Problems
32 025004) (see also Leitão and Svaiter (2018 Numer. Funct. Anal. Optim.
39 1153–80)). In the case of exact data, mean square convergence to zero of the iteration error is proven. In the noisy data case, we couple our method with an a priori stopping rule and characterize it as a regularization method for solving systems of linear ill-posed operator equations. Numerical tests are presented for two linear ill-posed problems: (i) a Hilbert matrix type system with over 108 equations; (ii) a big data linear regression problem with real data. The obtained results indicate superior performance of the proposed method when compared with other well-established random iterations. Our preliminary investigation indicates that the proposed iteration is a promising alternative for computing stable approximate solutions of large scale systems of linear ill-posed equations.
Picoliter liquid handling at gas/liquid interface by surface and geometry control in a micro-nanofluidic device
Authors: Morikawa Kyojiro , Murata Shin-ichi , Kazoe Yutaka , Mawatari Kazuma , Kitamori Takehiko
Published: December 2021

In micro- and nanofluidic devices, highly precise fluidic control is essential. Conventional mechanical valves in microchannels and nanochannels have size limitations, whereas hydrophobic (Laplace) valves are generally difficult to use for low-surface-tension liquids. In the present study, we developed a method for handling picoliter volumes of low-surface-tension liquids in a micro-nanofluidic device. The proposed Laplace valve is based on the pinning effect. A fused silica micro-nanofluidic device that includes a picoliter chamber whose geometry was designed to induce capillary pinning was designed and fabricated. The measured Laplace pressure of a lysis buffer (surfactant) was consistent with the calculated pressure, indicating successful fabrication and hydrophobic surface modification. The working principle of the Laplace valve was verified. The Laplace valve maintained the lysis buffer at the gas/liquid interface for 60 min, which is sufficiently long for cell lysis operations. Finally, replacement of liquids in the picoliter chamber using the valve was demonstrated. The proposed method will contribute to basic technologies for fluidic control in micro- and nanofluidic devices, and the proposed Laplace valve can be used for low-surface-tension liquids. In addition, the developed valve and picoliter chamber can be utilized for the interface in single-cell lysis, which will facilitate the development of single-cell analysis devices.
Microfluidic multicolor display by juxtapositional color mixing with a pattern of primary color pixels
Authors: Muramatsu Jumpei , Onoe Hiroaki
Published: December 2021

This paper describes a microfluidic multicolor display utilizing juxtapositional color mixing of pixels. Our display has a 14 × 14 array of pixels (2.5 mm in pixel diameter, 8.46 ppi) on the display surface where multicolor is expressed by controlling the pattern of the four primary color inks (cyan (C), magenta (M), yellow (Y), and black (= key plate, K)) that fill the pixels. The microfluidic display has a three-layer structure composed of a top layer with pixels for displaying images, a middle layer that serves as a background screen, and a bottom layer with microchannels that connect the pixels. In order to express multicolor by combining CMYK primary colors, we optimized the concentration of the inks used as the primary colors. By designing patterns of pixels filled with CMYK ink, color gradations and multicolor images were displayed on our display. The proposed microfluidic display could be applied to eye-friendly and low-energy-consumption flexible display applications including multi-purpose sign boards used in outdoors, wearing objects, and exterior/interior of vehicles and architects.
Extended model for optimizing high-order harmonic generation in absorbing gases
Authors: Major Balázs , Varjú Katalin
Published: December 2021

We report on an extended version of the one-dimensional model proposed by Constant et al (1999 Phys. Rev. Lett.
82 1668) to study phase matching of high-order harmonic generation in absorbing and dispersive medium. The model—expanded from zeroth to first order—can be used with media having a pressure profile varying linearly with propagation length. Based on the new formulas, the importance of having a generation medium that ends abruptly with a steep pressure gradient for achieving high flux is highlighted. In addition to further rule-of-thumb guidelines for harmonic-flux optimization, it is shown that having a steep increase of pressure in the beginning of the medium increases harmonic flux, while it also decreases the required medium length to reach the absorption-limited maximum.
Helium-like ions in d-dimensions: analyticity and generalized ground state Majorana solutions
Authors: Escobar-Ruiz A M , Olivares-Pilón H , Aquino N , Cruz S A
Published: December 2021

Non-relativistic helium-like ions (−e, −e, Ze) with static nucleus in a d-dimensional space

R

d

(d > 1) are considered. Assuming r
−1 Coulomb interactions, a two-parametric correlated Hylleraas-type trial function is used to calculate the ground state energy of the system in the domain Z ⩽ 10. For odd d = 3, 5, the variational energy is given by a rational algebraic function of the variational parameters while for even d = 2, 4 it is shown for the first time that it corresponds to a more complicated non-algebraic expression. This twofold analyticity will hold for any d. It allows us to construct reasonably accurate approximate solutions for the ground state energy E
0(Z, d) in the form of compact analytical expressions. We call them generalized Majorana solutions. They reproduce the first leading terms in the celebrated

1

Z

expansion, and serve as generating functions for certain correlation-dependent properties. The (first) critical charge Z
c vs d and the Shannon entropy

S

r

(

d

)

vs Z are also calculated within the present variational approach. In the light of these results, for the physically important case d = 3 a more general three-parametric correlated Hylleraas-type trial is used to compute the finite mass effects in the Majorana solution for a three-body Coulomb system with arbitrary charges and masses. It admits a straightforward generalization to any d as well. Concrete results for the systems e
−
e
−
e
+,

H

2

+

and H
− are indicated explicitly. Comparison of our variational analytical results with corresponding highly accurate numerical values reported in the literature indicates a fair agreement, within the limits of accuracy imposed by the approximate character of our treatment.
Capillary trees for passively pumping water
Authors: Zhang Xuewei , Lorente Sylvie
Published: December 2021

Capillary flows are an attractive feature for passive water harvesting as they require no external driving force to pull the fluid out within the capillary network. Here we analyze the architecture of capillary flow networks in a steady state, and the impact of the network morphology on the maximum mass flow rate that can be extracted for a fixed network volume and fixed network footprint. We develop a search algorithm to test the possible locations of all the junction and bifurcation nodes and the changes in diameter ratios with the objective of obtaining the maximum mass flow rate from the network. We define the capillary strength as a local indicator to determine the geometrical parameters of each channel that allow the overall mass flow rate to be sustained. It is shown that the diameter ratio of connected tubes for maximum mass flow rate depends on the distance from the network outlet, and therefore does not follow the Hess–Murray law. The superiority of dendritic architectures in the roots and canopy branches of capillary trees is demonstrated.
Square-root-like higher-order topological states in three-dimensional sonic crystals
Authors: Geng Zhi-Guo , Peng Yu-Gui , Lv Huanzhao , Xiong Zhan , Chen Zhaojiang , Zhu Xue-Feng
Published: December 2021

The square-root descendants of higher-order topological insulators were proposed recently, whose topological property is inherited from the squared Hamiltonian. Here we present a three-dimensional (3D) square-root-like sonic crystal by stacking the 2D square-root lattice in the normal (z) direction. With the nontrivial intralayer couplings, the opened degeneracy at the K–H direction induces the emergence of multiple acoustic localized modes, i.e., the extended 2D surface states and 1D hinge states, which originate from the square-root nature of the system. The square-root-like higher order topological states can be tunable and designed by optionally removing the cavities at the boundaries. We further propose a third-order topological corner state in the 3D sonic crystal by introducing the staggered interlayer couplings on each square-root layer, which leads to a nontrivial bulk polarization in the z direction. Our work sheds light on the high-dimensional square-root topological materials, and have the potentials in designing advanced functional devices with sound trapping and acoustic sensing.
Extended law of corresponding states: square-well oblates
Authors: Gómez de Santiago Miguel , Gurin Péter , Varga Szabolcs , Odriozola Gerardo
Published: December 2021

The vapour–liquid coexistence collapse in the reduced temperature, T

r
= T/T

c
, reduced density, ρ

r
= ρ/ρ

c
, plane is known as a principle of corresponding states, and Noro and Frenkel have extended it for pair potentials of variable range. Here, we provide a theoretical basis supporting this extension, and show that it can also be applied to short-range pair potentials where both repulsive and attractive parts can be anisotropic. We observe that the binodals of oblate hard ellipsoids for a given aspect ratio (κ = 1/3) with varying short-range square-well interactions collapse into a single master curve in the

Δ

B

2

*

–ρ

r
plane, where

Δ

B

2

*

=

(

B

2

(

T

)

−

B

2

(

T

c

)

)

/

v

0

, B
2 is the second virial coefficient, and v
0 is the volume of the hard body. This finding is confirmed by both REMC simulation and second virial perturbation theory for varying square-well shells, mimicking uniform, equator, and pole attractions. Our simulation results reveal that the extended law of corresponding states is not related to the local structure of the fluid.
Stabilizing effects of Ag doping on structure and thermal stability of FeN thin films
Authors: Niti  , Kumar Yogesh , Seema  , Reddy V R , Vas Joseph Vimal , Gupta Surbhi , Stahn Jochen , Gupta Ajay , Gupta Mukul
Published: December 2021

In this work, we investigated the effect of Ag doping (2–20 at.%) on the phase formation of iron mononitride (FeN) thin films. Together with deposition of FeN using reactive dc magnetron sputtering, Ag was also co-sputtered at various doping levels between 2–20 at.%. We found that doping of Ag around 5 at.% is optimum to not only improve the thermal stability of FeN but also to reduce intrinsic defects that are invariably present in (even in epitaxial) FeN. Conversion electron Mössbauer spectroscopy and N K-edge x-ray near edge absorption measurements clearly reveal a reduction of defects in Ag doped FeN samples. Moreover, Fe self-diffusion measurements carried out using secondary ion mass spectroscopy depth-profiling and polarized neutron reflectivity in 57Fe enriched samples exhibit an appreciable reduction in Fe self-diffusion in Ag doped FeN samples. Ag being immiscible with Fe and non-reactive with N, occupies grain-boundary positions as nanoparticles and prohibits the fast Fe self-diffusion in FeN.
The need to review low-dose decision-making in radiation protection
Authors: Coates Roger
Published: December 2021

The current approach in the system of protection, and the way in which it is implemented in regulation and practical application, has resulted in the allocation of significant and disproportionate societal resources to reduce relatively low-level exposures to even lower levels. The resulting exposure levels are often a fraction of the basic natural background level, and in particular are comparable to, or often significantly less than, the variability of natural background exposures due to individual decision-making, which the system of protection deems acceptable. There are arguments for a wider approach to decision-making at such low doses, recognising the uncertainties in radiation risk estimation and acknowledging the context that all human life takes place in a variable natural background radiation which generally dominates these lower dose exposures. Recommendations are presented for improvements in how decisions are made in controlling low doses.
Establishment of national diagnostic reference levels for computed tomography procedures in Sri Lanka: first nationwide dose survey
Authors: Amalaraj T , Satharasinghe Duminda , Pallewatte Aruna , Jeyasugiththan Jeyasingam
Published: December 2021

The main purpose of this study was to establish for the first time national diagnostic reference levels (NDRLs) for common computed tomography (CT) procedures in Sri Lanka. Patient morphometric data, exposure parameters and dose data such as volume CT dose index (CTDIvol) and dose–length product (DLP) were collected from 5666 patients who underwent 22 types of procedure. The extreme dose values were filtered before analysis to ensure that the data come from standard size patients. The median of the dose distribution was calculated for each institution, and the third quartile value of the median distribution was considered as the NDRL. Based on the inclusion and exclusion criteria, data from 4592 patients and 17 procedure types were considered for establishment of a NDRL, covering 41% of the country’s CT machines. The proposed NDRLs based on CTDIvoland DLP were: non-contrast-enhanced (NC) head, 82.2 mGy/1556 mGy cm; contrast-enhanced (CE) head, 82.2 mGy/1546 mGy cm; chest NC, 7.4 mGy/350 mGy cm; chest CE, 8.3 mGy/464 mGy cm; abdomen NC, 10.5 mGy/721 mGy cm; abdomen arterial (A) phase, 13.4 mGy/398 mGy cm; abdomen venous (V) phase, 10.8 mGy/460 mGy cm; abdomen delay (D) phase, 12.6 mGy/487 mGy cm; sinus NC, 30.2 mGy/452 mGy cm; lumbar spine NC, 24.1 mGy/1123 mGy cm; neck NC, 27.5 mGy/670 mGy cm; high-resolution CT of chest, 10.3 mGy/341 mGy cm; kidneys ureters and bladder NC, 19.4 mGy/929 mGy cm; chest to pelvis (CAP) NC, 10.8 mGy/801 mGy cm; CAP A, 10.4 mGy/384 mGy cm; CAP V, 10.5 mGy/534 mGy cm; CAP D, 16.8 mGy/652 mGy cm. Although the proposed NDRLs are comparable with those of other countries, the observed broad dose distributions between the CT machines within Sri Lanka indicate that dose optimisation strategies for the country should be implemented for most of the CT facilities.
Digitalization of the reporting of key comparisons for radionuclide metrology
Authors: Coulon Romain , Courte Sammy , Judge Steven , Michotte Carine , Nonis Manuel
Published: December 2021

The Bureau International des Poids et Mesures operates an international reference system (the SIR) to compare primary standards of radioactivity realized by National Metrology Institutes. Recently, the way of managing data relating to this system has been redesigned. The new model is fully integrated into the SI digital transformation initiated by the metrology community. The new approach automates the production of reports on the results from key comparison exercises for publication in the key comparison database, aiming to reduce the time needed to prepare reports without impacting quality. In operation for a year, the new system has produced 12 comparison reports within deadlines at a quality that meets the needs of the stakeholders in radionuclide metrology. The database and the software are controlled using the states-of-the-art Git version control system. In addition, thanks to the machine-readable database it produces, it paves the way for more digital data exchanges meeting the FAIR principles and directly accessible through a new application programming interface that is under development.
Measuring the uncertainty assessment of an experimental device used to determine the thermo-optico-physical properties of translucent construction materials
Authors: Delort M , Fakra D A H , Malet-Damour B , Gatina J C
Published: December 2021

Studying the thermo-optical properties of construction materials (i.e. thermal conductivity, optical reflectance, optical transmittance, and optical absorbance) is essential for improving human comfort within a building. Typically, these properties are measured independently using specific equipment. The emergence of new innovative construction structures, such as translucent materials, makes the experimental characterization of these properties more challenging to observe. Recently, a new device, called MulticoefMeter (McM), which rapidly and simultaneously measures all these properties, has been created. The study described in this article covers the calculation technique for estimating measurement uncertainties linked to morphology, the parts, and the physical formula of the experimental apparatus. The measurement uncertainty estimates are obtained from knowledge of the color of the system’s walls, placement, and form of the McM components, placement of the measurement sensors, and the application of measurement collection equipment. Therefore, a thorough calculation analysis was performed on the sub-systems. Calculations are divided into two categories: those based on mathematical tools and information given by the makers and those based on experimental observations obtained during reliability testing. These uncertainties originate from statistical tools, geometric tolerance of the system, comparison with standards, and the error propagation laws of the physical models’ link with the device. All these uncertainties were summed up and given a global value, no more than 5%, conforming to the ASTM standard (E1225). Finally, a general method to quantify the measurement uncertainty value of any experimental device was proposed.
Improved algorithm for minimum zone of roundness error evaluation using alternating exchange approach
Authors: Khlil Alhadi , Shi Zhanqun , Umar Abubakar , Ma BoTong
Published: December 2021

Based on computational geometry techniques, an improved algorithm for the minimum zone of roundness error evaluation using an alternating exchange method is presented. A minimum zone fitting function was created to enhance the roundness error evaluation. The function uses three candidate points to determine the initial solution: the expected centre, the mean circle radius, and the corresponding zone half-width. The best solution function is designed to use the initial solution as the input to determine the optimum solution for the minimum zone circle (MZC). The proposed algorithm was validated using data available in the literature. The roundness error evaluation comparison results demonstrate that the proposed method accurately detects both the centre error magnitude and MZC and overcomes the insufficiency of using selected colinear points for four selected points.
Research on spatial filtering velocity measurement method for an interdigital electrostatic sensor
Authors: Gao Heming , Zhong Susu
Published: December 2021

Particle velocity is an important parameter to describe the flow characteristics of gas–solid two-phase flows. It is also a tricky problem for parameter measurement of gas–solid flows. Aiming at the problem of the spatial filtering effect of an electrostatic sensor suffering from the effect of a spatial distribution of solid particles, a new type of interdigital electrostatic sensor is here proposed to resolve it. First the spatial filtering characteristics of the interdigital electrostatic sensor are analyzed through finite element simulation, obtaining that the spatial position and size of the solid particles have no effect on the peak frequency of the sensor output signal power spectrum, and the quantitative relationship between the velocity and peak frequency is derived. Then, experimental verification is carried out on an experimental platform of a gravity-conveying particle flow. Simulation and experimental results show that the interdigital electrostatic sensor eliminates the influence of particle spatial position and particle size on the velocity measurement results. In the velocity range of 2.97 m s−1 to 4.95 m s−1, the relative error of the measurement system is better than 5%, and the relative standard deviation of repeated measurements is within 3%.
Deformation mechanism of copper reinforced by three-dimensional graphene under torsion and tension
Authors: Li Jinming , Xu Yixin , Wang Miaocao , Zhu Fulong , Hu Jianxiong , Feng Chenzefang , Huang Yuhua , Zhang Xiang , Zhao Naiqin , He Chunnian
Published: December 2021

The mechanical behaviors of uniaxial torsional and tensional copper nanorod embedded with sp2-type hybrid graphene nanosheets (3DG/Cu) were investigated systematically using molecular dynamics methods. During the torsion process, graphene expanded the plastic deformation region of copper, while the plastic deformation in monocrystalline Cu cases was limited to a smaller area. 3DG/Cu responded to the torsion by one more plastic stage when plastic deformation spread along the length after the elastic response. Graphene improved the torsional loading capacity of the composite material, greatly extending the effective response range of the material by distributing the deformation of copper along with the graphene rather than being concentrated at a certain position like monocrystalline Cu. Generally, as the length of the model increased, this enhancement decreased. The copper portion of 3DG/Cu was divided into three areas during uniaxial tensile, a static region, a quasi-static region of the middle portion where the shear and necking occurred, and a dynamic area near the loading end. However, the inside graphene kept continuous until fracture. Furthermore, graphene improved the yield strain of copper by maintaining intact after copper failure. The greater the pre-loaded torsion angle, the smaller the yield strength and Young’s modulus of 3DG/Cu.
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

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

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

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

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

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

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

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

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

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

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

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

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

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

Controlling 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

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

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.