bluuebunny/crossref_metadata_2025 huggingface dataset:
TaFeB spacer for soft magnetic composite free layer in CoFeB/MgO/CoFeB-based magnetic tunnel junction
Authors: Nakano Takafumi , Fujiwara Kosuke , Kumagai Seiji , Ando Yasuo , Oogane Mikihiko
Published: February 2023

CoFeB/MgO/CoFeB-based magnetic tunnel junctions (MTJs) with a soft magnetic composite free layer have been developed for magnetic sensor applications. Tunnel magnetoresistance (TMR) ratios in the sensor-type MTJs have reached a ceiling due to a trade-off between the TMR ratio and interlayer exchange coupling (IEC) depending on the spacer thickness of the composite free layer. In this study, we developed a paramagnetic amorphous TaFeB-alloy spacer to replace the conventional Ta spacer and solve this trade-off. The TaFeB film showed a wider thickness window for a sufficient IEC, resulting in IEC energy values of 0.18–0.19 erg/cm2 at a thickness of 1.0 nm. In addition, we confirmed that the TaFeB film had an ability to function as a boron sink comparable to that of pure Ta. These characteristics allowed us to thicken the TaFeB spacer up to 1.0 nm in the sensor-type MTJs and attain an enhanced TMR ratio of up to 234%, which is the highest compared with cases using the conventional Ta spacer reported to date. These findings demonstrate that TaFeB alloy is a promising material for breaking the ceiling of sensor-type MTJs and increasing sensitivity.
Non-linear correlation functions and zero-point energy flow in mixed quantum–classical semiclassical dynamics
Authors: Malpathak Shreyas , Ananth Nandini
Published: February 2023

Mixed quantum classical (MQC)-initial value representation (IVR) is a recently introduced semiclassical framework that allows for selective quantization of the modes of a complex system. In the quantum limit, MQC reproduces the semiclassical Double Herman–Kluk IVR results, accurately capturing nuclear quantum coherences and conserving zero-point energy. However, in the classical limit, although MQC mimics the Husimi-IVR for real-time correlation functions with linear operators, it is significantly less accurate for non-linear correlation functions with errors even at time zero. Here, we identify the origin of this discrepancy in the MQC formulation and propose a modification. We analytically show that the modified MQC approach is exact for all correlation functions at time zero, and in a study of zero-point energy (ZPE) flow, we numerically demonstrate that it correctly obtains the quantum and classical limits as a function of time. Interestingly, although classical-limit MQC simulations show the expected, unphysical ZPE leakage, we find that it is possible to predict and even modify the direction of ZPE flow through selective quantization of the system, with the quantum-limit modes accepting energy but preserving the minimum quantum mechanically required energy.
A review of cryogenic neuromorphic hardware
Authors: Islam Md Mazharul , Alam Shamiul , Hossain Md Shafayat , Roy Kaushik , Aziz Ahmedullah
Published: February 2023

The revolution in artificial intelligence (AI) brings up an enormous storage and data processing requirement. Large power consumption and hardware overhead have become the main challenges for building next-generation AI hardware. To mitigate this, neuromorphic computing has drawn immense attention due to its excellent capability for data processing with very low power consumption. While relentless research has been underway for years to minimize the power consumption in neuromorphic hardware, we are still a long way off from reaching the energy efficiency of the human brain. Furthermore, design complexity and process variation hinder the large-scale implementation of current neuromorphic platforms. Recently, the concept of implementing neuromorphic computing systems in cryogenic temperature has garnered intense interest thanks to their excellent speed and power metric. Several cryogenic devices can be engineered to work as neuromorphic primitives with ultra-low demand for power. Here, we comprehensively review the cryogenic neuromorphic hardware. We classify the existing cryogenic neuromorphic hardware into several hierarchical categories and sketch a comparative analysis based on key performance metrics. Our analysis concisely describes the operation of the associated circuit topology and outlines the advantages and challenges encountered by the state-of-the-art technology platforms. Finally, we provide insight to circumvent these challenges for the future progression of research.
Toward a quasiphase transition in the single-file chain of water molecules: Simple lattice model
Authors: Druchok Maksym , Krasnov Volodymyr , Krokhmalskii Taras , Cardoso e Bufalo Tatiana , Martins de Souza Sergio , Rojas Onofre , Derzhko Oleg
Published: February 2023

Recently, Ma et al. [Phys. Rev. Lett. 118, 027402 (2017)] have suggested that water molecules encapsulated in (6,5) single-wall carbon nanotube experience a temperature-induced quasiphase transition around 150 K interpreted as changes in the water dipoles orientation. We discuss further this temperature-driven quasiphase transition performing quantum chemical calculations and molecular dynamics simulations and, most importantly, suggesting a simple lattice model to reproduce the properties of the one-dimensional confined finite arrays of water molecules. The lattice model takes into account not only the short-range and long-range interactions but also the rotations in a narrow tube, and both ingredients provide an explanation for a temperature-driven orientational ordering of the water molecules, which persists within a relatively wide temperature range.
Photothermally induced temperature variations in a low-absorption sample via backside absorption
Authors: Miletic V. V. , Popovic M. N. , Galovic S. P. , Markushev D. D. , Nesic M. V.
Published: February 2023

In order to make the photothermal effect detectable from a sample with low optical absorption, an optically opaque layer must be applied on its surface. A model of optically induced temperature variations for such a structure is derived, with a very thin coating applied on the non-illuminated (back) side of the sample and neglecting heat flux dissipation in the coating. Validation of the model is performed by comparing the obtained results with the results for the corresponding two-layer structure model. The influence of optical absorption on surface temperature variations of both optically transparent and semi-transparent film, whether the film is a good or poor thermal conductor, is analyzed. It is shown that the effects of optical absorption in the coated structure can be observed through variations in the measured temperature, despite the low absorbance of the sample.
Inside the ovonic threshold switching (OTS) device based on GeSbSeN: Structural analysis under electrical and thermal stress
Authors: Laguna C. , Bernard M. , Garrione J. , Fillot F. , Aussenac F. , Rouchon D. , Lima G. , Militaru L. , Souifi A. , Navarro G.
Published: February 2023

In this article, we present the structural investigation by Raman spectroscopy of GeSbSeN ovonic threshold switching (OTS) material once integrated in selector devices featuring a top electrode based on a transparent and conductive indium tin oxide layer. The devices are characterized by standard electrical protocols, and the structural evolution of the material is investigated after several switching operations. The results are correlated with the spectra obtained from blanket samples annealed at increasing temperature and are supported by XRD and TEM analyses. We establish a link between the evolution of the material structure with the annealing process and the device behavior along cycling, bringing important advancement in the understanding of the switching mechanism and of the origin of the failure in OTS devices.
A dual-cantilever based MEMS PZT thick-film energy harvester with enhanced internal resonance performance
Authors: Feng Xiaowei , Huang Manjuan , Liu Huicong , Sun Lining
Published: February 2023

In this paper, a multi-frequency vibrational piezoelectric energy harvester (PEH) with a dual-microcantilever coupled structure based on the internal resonance effect is proposed. The device consists of a low-frequency cantilever and a high-frequency cantilever with an integer multiple of resonant frequencies connected by a clamped–clamped coupling beam. The internal resonant PEH (IR-PEH) is prepared by the microelectromechanical systems piezoelectric thick-film process based on the flexible thin metal substrate. The output performance of the proposed PEH device is greatly improved by taking advantages of the internal coupling structure and the piezoelectric thick-film microfabrication process. Under the excitation acceleration of 2 g, the maximum power output of IR-PEH reaches 424.6 μW at 190 Hz and 108.8 μW at 365 Hz, which increases by 35% of the power output due to the internal resonance coupling comparing with the PEH without the coupling effect. The corresponding power densities of IR-PEH reach 6.3 and 1.6 mW/cm3, respectively. This IR-PEH configuration induces the competitive advantages of good performance, wide bandwidth, and small volume, which can be potentially employed as a power source for low power wireless sensing nodes.
Significant magneto-dielectric effect in SrNd2Fe2O7 at room temperature
Authors: Chen Li-Da , Shu Li-Huai , Zhang Bi Hui , Liu Lin , Lei Lin , Shao Ye , Huang Feng-Zhen , Lv Yang-Yang , Cheng Zhen-Xiang , Wang Jian-Li , Stewart G. A. , Cadogan J. M. , Hutchison W. D. , Zhou Jian , Liu Xiao Qiang , Yao Shu-Hua , Chen Y. B. , Chen Yan-Feng
Published: February 2023

Here, we report the growth of (Sr, Ca) Nd2Fe2O7 single crystals with the Ruddlesden–Popper structure using an optical floating-zone method. A significantly anisotropic magneto-dielectric effect (MD), ab-plane and c-axial MD coefficients reaching −12.3% and −8.4% measured at 103 Hz in a 1 T magnetic field, can be obtained in a SrNd2Fe2O7 crystal at room temperature. The corresponding anisotropic MD ratio can be reached as high as 1.46. With an increase in the Ca concentration, the MD effect decreases dramatically and is eventually completely suppressed in both directions. Analysis of magnetic properties and 57Fe Mössbauer spectra suggests that the anisotropic MD effects in SrNd2Fe2O7 can be attributed to polaronic hopping between two neighboring Fe3+ ions through oxygen vacancies in an anisotropically antiferromagnetic matrix; the disappearance of the MD effect in Ca-doped SrNd2Fe2O7 is a consequence of the suppression of the antiferromagnetism. Our work suggests that the significantly anisotropic MD effect in SrNd2Fe2O7 crystals at room temperature can be used in magneto-dielectric controlled devices.
Leaky-wave radiating surface on heterogeneous high-κ material for monolithic antenna-frontend integration
Authors: Askarian Amirhossein , Yao Jianping , Lu Zhenguo , Wu Ke
Published: February 2023

In a highly integrated analog radio-over-fiber transceiver, seamless integration of the antenna-frontend is crucial as an antenna is generally implemented on a high-κ material, which is set to highly degrade the antenna's performance. This work is concerned with the radiation behavior improvement of a planar leaky-wave antenna with an inductive partially reflecting surface (PRS) on a high-κ substrate for the development of a highly directive antenna. To begin with, we show how a thin and single-mode resonance (SMR) inductive PRS on high-κ materials in a planar leaky-wave antenna is set to provoke two resonance frequencies (i.e., PRS and cavity resonances) to converge, thereby diminishing the antenna's broadside directivity. By applying an equivalent circuit model, we explain how a multi-mode resonance (MMR) PRS can adequately be applied to address the underlying challenges. Subsequently, the leaky-wave radiation behavior of an antenna with a heterogeneous substrate is investigated and analytical equations are derived and verified with a full-wave simulation. The effects of material permittivity and thickness in a heterogeneous-cavity antenna on leaky-wave performance are investigated using these approximate yet accurate-enough equations. To justify the findings, two 9 × 9 planar leaky-wave antennas are prototyped on heterogeneous substrates based on SMR and MMR PRS and the radiation performances are compared. Our investigations reveal that in the proposed scenario, an MMR PRS can significantly enhance the antenna's broadside directivity by over 4 dBi at the resonance frequency (27.5 GHz), which is also set to improve radiation pattern compared to a SMR-based antenna. Finally, a single-fed dual-band aperture-shared antenna with a large frequency ratio (S-band and Ka-band) is developed and fabricated on a high-κ substrate based on the proposed MMR PRS.
Resonance dependence of electrically reconfigurable VO2-based THz metadevice for memory information processing
Authors: Liang Wanlin , Li Ge , Zhou Qingli , Zhang Ziye , Zhang Suqi , Ning Tingyin , Zhang Pujing , Deng Yuwang , Zhang Cunlin , Ge Chen , Jin Kuijuan
Published: February 2023

A terahertz hybrid metamaterial incorporated with active media VO2 holds great promise for the realization of a new generation of reconfigurable and multifunctional devices. However, for the electrical control, many efforts on reducing high working threshold are usually based on the utilization of patterned VO2 patches or additional insulation layers, which will increase the complexity of the fabrication procedure. Here, we have proposed an effective strategy only by combining the surface microstructure and the unpatterned VO2 film to realize the tunability of working current and uncover its highly dependent correlation with the structural resonance responses. It is shown the fully modulated current in our hybrid metastructures can be reduced with the prominently separated hysteresis loops. Further developed binary encoders can perform not only the information transformation of the fixed code symbols but also the arbitrary encoding with the programmable current pulse. Additionally, the dynamic color display can be accomplished to illustrate the intriguing function of the information encryption and multi-image reappearance with the current as the decryption key. Our work provides an approach to reduce the operating current and paves a pathway for the development of photonic memory information processors.
A thermal boundary resistance measurement method based on a designed chip with the heat source separated from the temperature sensor
Authors: Li Xuan , Feng Shiwei , Feng Zhihong , Pan Shijie , Lv Yuanjie , Bai Kun , Lu Xiaozhuang , Qin Junhua , Zhang Yamin
Published: February 2023

Measurements of thermal boundary resistance (TBR) are of great significance in the fields of electronic packaging and thermal management. In this study, a measurement method based on a designed 1 × 1 mm2 chip with a heat source separated from a temperature sensor was developed. The chip consists of a temperature sensor with nine Schottky diodes connected in series and a heat source composed of metal wires, which are separated by SiO2 to realize electrical isolation. With this chip, the TBR of samples can be extracted from transient temperature response curves of GaN on a Si wafer using the structure function and transient dual interface test methods. In particular, the surface of samples was etched with uniform arrays to increase the measurement accuracy. The TBR measurements of four samples etched on the same wafer under different conditions were 1.62 ± 0.22 × 10−8, 1.6 ± 0.38 × 10−8, 1.49 ± 0.18 × 10−8, and 1.6 ± 0.35 × 10−8 m2K/W, indicating consistency of the results. This chip effectively expands the application of the structure function method to TBR measurements, which can be helpful for further research on interfacial heat transport.
Large-scale fabrication of CMOS-compatible silicon-OLED heterojunctions enabled infrared upconverters
Authors: Rao Tianyu , Hao Qun , Mu Ge , Qin Tianling , Tan Yimei , Zhao Pengfei , Kong Dexi , Chen Menglu , Tang Xin
Published: February 2023

Infrared-to-visible upconverters have widespread application prospects, including bioimaging, night vision, and defense security. A typical upconverter is generally constructed by integrating an infrared photodetector (PD) detecting low-energy infrared with a visible light-emitting diode (LED) emitting high-energy visible light. However, when photocarriers transport through the interface between PD and LED, lateral current spreading is inevitably present, which leads to optical cross-talking and hinders the realization of high-resolution and large-area infrared imaging. Here, near-infrared (NIR) upconverters are fabricated via the integration of silicon (Si) NIR detectors with organic LED (OLED) by complementary metal–oxide–semiconductor compatible manufacturing processes. The pixelated indium tin oxide electrodes introduced as the interfacial carrier transfer channel effectively suppress the lateral current spreading and ensure that the photogenerated carrier of PD could transport into the OLED with a well-defined spatial resolution. The Si-OLED upconverters possess a wafer-level luminous area and large-scale fabrication capacity and realize high-resolution infrared imaging with a resolution as high as 3629 dpi. By changing the organic luminescent layer of OLED, the Si-OLED upconverters could emit red/green/blue visible light under NIR illumination with a low turn-on voltage of 3 V and an excellent upconversion efficiency of 9.2%. Furthermore, the large-area Si-OLED upconverters exhibit flexibility with an infrared upconversion ability even under bending.
How protein topology controls allosteric regulations
Authors: Xie Juan , Pan Gaoxiang , Li Yibo , Lai Luhua
Published: February 2023

Allostery is an important regulatory mechanism of protein functions. Among allosteric proteins, certain protein structure types are more observed. However, how allosteric regulation depends on protein topology remains elusive. In this study, we extracted protein topology graphs at the fold level and found that known allosteric proteins mainly contain multiple domains or subunits and allosteric sites reside more often between two or more domains of the same fold type. Only a small fraction of fold–fold combinations are observed in allosteric proteins, and homo-fold–fold combinations dominate. These analyses imply that the locations of allosteric sites including cryptic ones depend on protein topology. We further developed TopoAlloSite, a novel method that uses the kernel support vector machine to predict the location of allosteric sites on the overall protein topology based on the subgraph-matching kernel. TopoAlloSite successfully predicted known cryptic allosteric sites in several allosteric proteins like phosphopantothenoylcysteine synthetase, spermidine synthase, and sirtuin 6, demonstrating its power in identifying cryptic allosteric sites without performing long molecular dynamics simulations or large-scale experimental screening. Our study demonstrates that protein topology largely determines how its function can be allosterically regulated, which can be used to find new druggable targets and locate potential binding sites for rational allosteric drug design.
Frequency and field-dependent response of confined electrolytes from Brownian dynamics simulations
Authors: Hoang Ngoc Minh Thê , Stoltz Gabriel , Rotenberg Benjamin
Published: February 2023

Using Brownian dynamics simulations, we investigate the effects of confinement, adsorption on surfaces, and ion–ion interactions on the response of confined electrolyte solutions to oscillating electric fields in the direction perpendicular to the confining walls. Nonequilibrium simulations allows to characterize the transitions between linear and nonlinear regimes when varying the magnitude and frequency of the applied field, but the linear response, characterized by the frequency-dependent conductivity, is more efficiently predicted from the equilibrium current fluctuations. To that end, we (rederive and) use the Green–Kubo relation appropriate for overdamped dynamics, which differs from the standard one for Newtonian or underdamped Langevin dynamics. This expression highlights the contributions of the underlying Brownian fluctuations and of the interactions of the particles between them and with external potentials. Although already known in the literature, this relation has rarely been used to date, beyond the static limit to determine the effective diffusion coefficient or the DC conductivity. The frequency-dependent conductivity always decays from a bulk-like behavior at high frequency to a vanishing conductivity at low frequency due to the confinement of the charge carriers by the walls. We discuss the characteristic features of the crossover between the two regimes, most importantly how the crossover frequency depends on the confining distance and the salt concentration, and the fact that adsorption on the walls may lead to significant changes both at high and low frequencies. Conversely, our results illustrate the possibility to obtain information on diffusion between walls, charge relaxation, and adsorption by analyzing the frequency-dependent conductivity.
Aggregation and crystallization of small alkanes
Authors: Shakirov Timur , Paul Wolfgang
Published: February 2023

We present a computer simulation study of the aggregation and ordering of short alkane chains using a united atom model description. Our simulation approach allows us to determine the density of states of our systems and, from those, their thermodynamics for all temperatures. All systems show a first order aggregation transition followed by a low-temperature ordering transition. For a few chain aggregates of intermediate lengths (up to N = 40), we show that these ordering transitions resemble the quaternary structure formation in peptides. In an earlier publication, we have already shown that single alkane chains fold into low-temperature structures, best described as secondary and tertiary structure formation, thus completing this analogy here. The aggregation transition in the thermodynamic limit can be extrapolated in pressure to the ambient pressure for which it agrees well with experimentally known boiling points of short alkanes. Similarly, the chain length dependence of the crystallization transition agrees with known experimental results for alkanes. For small aggregates, for which volume and surface effects are not yet well separated, our method allows us to identify the crystallization in the core of the aggregate and at its surface, individually.
Normal ordering of the angular momentum cylindrical ladder operators and their products with Wigner D0,ε1 functions
Authors: Chang Xuanhao , Millionshchikov Dmitry V. , Efremov Ilya M. , Krasnoshchekov Sergey V.
Published: February 2023

The operator canonical perturbation theory (CPT) is an efficient tool for solving the molecular vibration–rotation Schrödinger equation. The corresponding Watson Hamiltonian can be written using angular momentum cylindrical ladder operators (Jz, J± = Jx ∓ iJy) possessing the Lie algebra su(2) commutation relations [J+, J−] = 2Jz, [Jz, J±] = ±J±. The reduced effective Hamiltonians suitable for fitting to observed spectra are traditionally based on Hermitian basis sets, e.g., (J2)lJzn,(J+m+J−m)+. It is beneficial to re-express such Hamiltonians using sums of normal ordered products of ladder operators JzaJ+bJ−c. For instance, in the CPT, the unitary transformations reduce to the normal ordering problem. Similarly, the dipole moment transition probabilities can be evaluated using Wigner functions, D0,ε1(ε=0,±1), possessing complex commutation relations with Jα-operators. The related line strengths are proportional to the squared matrix elements of the unitary transformed dipole moment operator given by a polynomial in normal ordered products D0,ε1JzaJ+bJ−c. We have applied the technique of combinatorial calculations associated with the classical representation theory and obtained compact formulas for normal ordering of the typical raw products JzaJ+bJ−cJzdJ+eJ−f and JzaJ+bJ−cD0,ε1. The theory of universal enveloping Lie algebras and representation theory show that the resulting formulas cannot be further improved from the mathematical point of view. The results have a wide scope of applications in other fields of physics, including other operators with the same commutation properties. The resulting expressions for normal orderings and routines for evaluation of matrix elements, as well as the systematic tests of working formulas, were coded in Fortran and the software is available through the GitHub hosting service.
Gatekeeper mutations activate FGF receptor tyrosine kinases by destabilizing the autoinhibited state
Authors: Besch Alida , Marsiglia William M. , Mohammadi Moosa , Zhang Yingkai , Traaseth Nathaniel J.
Published: February 2023

Many types of human cancers are being treated with small molecule ATP-competitive inhibitors targeting the kinase domain of receptor tyrosine kinases. Despite initial successful remission, long-term treatment almost inevitably leads to the emergence of drug resistance mutations at the gatekeeper residue hindering the access of the inhibitor to a hydrophobic pocket at the back of the ATP-binding cleft. In addition to reducing drug efficacy, gatekeeper mutations elevate the intrinsic activity of the tyrosine kinase domain leading to more aggressive types of cancer. However, the mechanism of gain-of-function by gatekeeper mutations is poorly understood. Here, we characterized fibroblast growth factor receptor (FGFR) tyrosine kinases harboring two distinct gatekeeper mutations using kinase activity assays, NMR spectroscopy, bioinformatic analyses, and MD simulations. Our data show that gatekeeper mutations destabilize the autoinhibitory conformation of the DFG motif locally and of the kinase globally, suggesting they impart gain-of-function by facilitating the kinase's ability to populate the active state.
Probing FeSi, a
d
-electron topological Kondo insulator candidate, with magnetic field, pressure, and microwaves
Authors: Breindel Alexander J. , Deng Yuhang , Moir Camilla M. , Fang Yuankan , Ran Sheng , Lou Hongbo , Li Shubin , Zeng Qiaoshi , Shu Lei , Wolowiec Christian T. , Schuller Ivan K. , Rosa Priscila F. S. , Fisk Zachary , Singleton John , Maple M. Brian
Published: February 2023

Recently, evidence for a conducting surface state (CSS) below 19 K was reported for the correlated
d
-electron small gap semiconductor FeSi. In the work reported herein, the CSS and the bulk phase of FeSi were probed via electrical resistivity ρ measurements as a function of temperature
T
, magnetic field
B
to 60 T, and pressure
P
to 7.6 GPa, and by means of a magnetic field-modulated microwave spectroscopy (MFMMS) technique. The properties of FeSi were also compared with those of the Kondo insulator SmB
6
to address the question of whether FeSi is a
d
-electron analogue of an
f
-electron Kondo insulator and, in addition, a “topological Kondo insulator” (TKI). The overall behavior of the magnetoresistance of FeSi at temperatures above and below the onset temperature
T
S
= 19 K of the CSS is similar to that of SmB
6
. The two energy gaps, inferred from the ρ(
T
) data in the semiconducting regime, increase with pressure up to about 7 GPa, followed by a drop which coincides with a sharp suppression of
T
S
. Several studies of ρ(
T
) under pressure on SmB
6
reveal behavior similar to that of FeSi in which the two energy gaps vanish at a critical pressure near the pressure at which
T
S
vanishes, although the energy gaps in SmB
6
initially decrease with pressure, whereas in FeSi they increase with pressure. The MFMMS measurements showed a sharp feature at
T
S
≈ 19 K for FeSi, which could be due to ferromagnetic ordering of the CSS. However, no such feature was observed at
T
S
≈ 4.5 K for SmB
6
.
Cholesterol-rich domain formation mediated by ZO proteins is essential for tight junction formation
Authors: Shigetomi Kenta , Ono Yumiko , Matsuzawa Kenji , Ikenouchi Junichi
Published: February 2023

Tight junctions (TJs) are cell-adhesion structures responsible for the epithelial barrier. We reported that accumulation of cholesterol at the apical junctions is required for TJ formation [K. Shigetomi, Y. Ono, T. Inai, J. Ikenouchi,J. Cell Biol.217, 2373–2381 (2018)]. However, it is unclear how cholesterol accumulates and informs TJ formation—and whether cholesterol enrichment precedes or follows the assembly of claudins in the first place. Here, we established an epithelial cell line (claudin-null cells) that lacks TJs by knocking out claudins. Despite the lack of TJs, cholesterol normally accumulated in the vicinity of the apical junctions. Assembly of claudins at TJs is thought to require binding to zonula occludens (ZO) proteins; however, a claudin mutant that cannot bind to ZO proteins still formed TJ strands. ZO proteins were however necessary for cholesterol accumulation at the apical junctions through their effect on the junctional actomyosin cytoskeleton. We propose that ZO proteins not only function as scaffolds for claudins but also promote TJ formation of cholesterol-rich membrane domains at apical junctions.
Quality control ensures fidelity in ribosome assembly and cellular health
Authors: Parker Melissa D. , Karbstein Katrin
Published: February 2023

The coordinated integration of ribosomal RNA and protein into two functional ribosomal subunits is safeguarded by quality control checkpoints that ensure ribosomes are correctly assembled and functional before they engage in translation. Quality control is critical in maintaining the integrity of ribosomes and necessary to support healthy cell growth and prevent diseases associated with mistakes in ribosome assembly. Its importance is demonstrated by the finding that bypassing quality control leads to misassembled, malfunctioning ribosomes with altered translation fidelity, which change gene expression and disrupt protein homeostasis. In this review, we outline our understanding of quality control within ribosome synthesis and how failure to enforce quality control contributes to human disease. We first provide a definition of quality control to guide our investigation, briefly present the main assembly steps, and then examine stages of assembly that test ribosome function, establish a pass–fail system to evaluate these functions, and contribute to altered ribosome performance when bypassed, and are thus considered “quality control.”
Zinc film anodes for air microbatteries: fabrication, approaches, and utilization optimization
Authors: Venkatesh Vishal , Yang Qi , Zhang Jingwen , Huang Yanghang , Pikul James H , Allen Sue Ann Bidstrup , Allen Mark G
Published: February 2023

Portable and autonomous microdevices often require on-board power sources such as thin film microbatteries. Air microbatteries are an attractive power source for such devices due to their high specific energy density. One particularly appropriate air chemistry is based on Zn, due to the multiple microfabrication approaches compatible with Zn anode formation. We demonstrate fabrication approaches to realize Zn film anodes in different thickness regimes using microelectromechanical systems based fabrication techniques—evaporation, electrodeposition, and laser micromachining; and evaluate their relative performance as power sources in a primary battery configuration. These fabrication techniques enable films in thickness regimes ranging from the micron scale to hundreds of microns. The fabricated films have been characterized using scanning electron microscopy and energy dispersive x-ray spectroscopy, and were found to be dense and reasonably free from impurities. The electrochemical and discharge properties of the fabricated films were studied in an air battery configuration comprising a Zn anode-alkaline hydrogel electrolyte-metal catalyst stack, in which the anode had a surface area of 0.78 cm2. Evaporated Zn anodes (1–10 µms) yielded Zn utilizations of 96.5% and 82% at 10 and 1 mA discharge rates, respectively. The specific capacity of the evaporated Zn anodes was 791 mAh g−1 when discharged at 10 mA, close to the Zn theoretical specific capacity of 820 mAh g−1. Electrodeposited Zn anodes (10–100 µms) yielded utilizations of 90.2% and 75.6% at 10 and 1 mA discharge rates, respectively. Laser micromachined Zn anodes (250 µms) yielded Zn utilization of 90% when discharged at 10 mA. These fabrication techniques offer the potential to realize high energy density Zn anodes of different thickness ranges for thin film microbatteries, which can be tailored to microdevice-based applications of interest.
Performance enhancement of piezoelectric bulk mode MEMS mode-matched gyroscopes based on a secondary phase feedback loop
Authors: Chang Chin-Yu , Wang Shang-Wei , Li Sheng-Shian
Published: February 2023

This work investigates the performance enhancement of piezoelectric bulk mode mode-matched gyroscopes based on a secondary phase feedback loop. An independent phase feedback loop realized by a lock-in amplifier is applied on a 10 MHz multiple ports piezoelectric device to harness its effective stiffness and damping factor for better gyroscope performance. The multiple ports device is designed based on support transducer topology with eight transducer arms, some of which drive the central resonant tank into a secondary elliptical mode. Open-loop measurement with varied phase delay is adopted to carry out the best working condition (i.e. higherQ-factor, smaller frequency split). Therefore, the measured scale factor results in a 1.56 times improvement through boosting theQ-factor of the driving mode. The minimum frequency split compensated by the phase feedback could reach 13.4 ppm with a tuning phase of 60° and tuning voltage of 0.1 V. The bias instability of the proposed gyro through the help of phase feedback loop could be reduced by 2.13 times. The achievement in this work has shown that the phase feedback mechanism could indeed help to improve the performance of the resonant transducers.
Design of a bifocal metalens with tunable intensity based on deep-learning-forward genetic algorithm
Authors: Wang Fang , Shu Xuewen
Published: February 2023

Metalenses, which control the amplitude, phase, and polarization state of incident waves based on metasurface to achieve focusing and imaging, have many important applications in various optical systems. We design a bifocal metalens that can independently control the focusing of right-handed circularly polarized light and left-handed circularly polarized light. Due to the demand for enormous simulations, traditional design methods are extremely time-consuming. Here, we propose a deep-learning-forward genetic algorithm to efficiently design the metalens parameters. The numerical simulation results of the metalens are in good agreement with the theoretical results. Meanwhile, it is flexible to change intensity ratio of the two foci through altering incident light ellipticity without redesigning the light intensity profile. This work provides a novel approach to multifunctional metasurface device realization.
A broadband zigzag-shaped energy harvester for both wind energy and vibration energy: modeling and experimental verification
Authors: Pan Jianan , Zhang Xuhui , Qin Weiyang , Xu Hengtao , Tian Hao , Zhu Fulin , Guo Yan
Published: February 2023

In this work, a novel zigzag-shaped energy harvester is proposed to harvest wind energy and vibration energy simultaneously in a practical environment. The harvester is constituted of an inclined beam and a horizontal beam with a bluff body fixed at the free end. The inclined beam is covered by a piezoelectric patch. The vibration induced by the wind flow and base excitation produces electric energy through the piezoelectric material and realizes energy harvesting. In particular, the softening characteristic created by the magnetic interaction can extend the working bandwidth. Dynamical coupling equations are derived, and the corresponding simulations are carried out. The results show that the cubic bluff body can help increase the wind-induced energy harvesting. The responses obtained under base excitation combined with wind flow demonstrate that the hybrid excitation can provide a significant enhancement to the non-resonance region. Related validation experiments are carried out. The experimental results are in good agreement with the numerical results. Compared with the conventional base excitation or wind flow excitation, the output power obtained under hybrid excitation increases by 106% and 206%, respectively.
A novel compound fault diagnosis method for rolling bearings based on graph label manifold metric transfer
Authors: Wang Guangbin , Zhao Shubiao , Chen Jinhua , Zhong Zhixian
Published: February 2023

Metric transfer learning overcomes the problem of no domain distribution alienation in traditional sample transfer, and also improves the classification accuracy. However, some problems exist; for example, the target domain must have labelled samples without considering the manifold connection between data samples, and the algorithm is not robust under sparse samples. A compound fault diagnosis method for rolling bearings based on graph label manifold metric transfer is proposed. First, the pseudo-label of the target domain is acquired through a weighted graph constructed on the source domain with known fault labels. In order to ensure the accuracy of metrics in manifold space, we adopt the method of graph label propagation (LP) to gradually spread the label information. Then, the sample data are mapped to the low-dimensional manifold space by locality preserving projections (LPP), which gives higher weight to the source domain samples close to the target domain to solve the domain offset problem. At the same time, combined with the labelled samples of the target domain in LP, the manifold distance measure is learned to minimize the intra-class distance and maximize the class spacing, eliminate the overlap phenomenon in the domain and realize the distribution alienation between classes in the domain. After each iteration, unsupervised manifold metric transfer learning is realized by increasing the range of LP and gradually reducing the error of graph LP. Experiments show that the new unsupervised transfer learning method has better fault identification ability than the semi-supervised transfer learning method. In the case of sparse training samples, it still maintains a high diagnostic accuracy, and the highest fault recognition accuracy can reach more than 97% with good robustness.
A novel method for measuring radial and axial errors in a cylindrical coordinate system using a combined double ball bar
Authors: Sun Tao , Wang Wen , Wang Chuanyong , Chen Zhanfeng , Sang Zhiqian , Lu Keqing , Xu Kaifei , Wu Haimei , Ju Bing-Feng
Published: February 2023

Multiaxis machine tools are widely used in manufacturing. The measurement of motion error is important to improve the machining accuracy of machine tools. A double ball bar (DBB), as a high-precision single-dimensional position reading device, is widely used to measure the motion error of the circular path of machine tools. However, the motion errors contain the cylindrical radial and axial errors with respect to the circular path plane. Therefore, the measurement results of the DBB are incomplete because they do not contain axial errors. To measure the motion error of the circular path accurately, completely and concisely, a novel measurement method based on the combined DBB (C-DBB) is proposed in this paper, which can directly measure the radius and axial motion error of the circular path in one measurement. First, the measuring principle of the C-DBB method is introduced, and the measurement model of the radius and axial motion error of the circular path is established. Then, a measuring device using the C-DBB method was designed based on the lever principle, and the error parameters of the designed device were analyzed. According to the error analysis results, the measurement results of the C-DBB method were compensated and corrected. Finally, the C-DBB method is used to measure the circular path on the vertical CNC milling machine, and the results are compared with the measurement results using the DBB method. It is shown that the proposed C-DBB method can obtain high-precision multidimensional motion error in a single measurement, and the designed measuring device based on the C-DBB method has high repeatability and good circular path measuring ability. The proposed method provides an effective method for machine tool multidimensional motion error measurement and compensation.
Influence of filament number and size on the basic properties of in situ made MgB2 wires
Authors: Kováč P , Berek D , Melišek T , Kováč J , Hušek I , Búran M , Lee D G , Choi J H
Published: February 2023

Monel-sheathed MgB2 wires with 6, 18 and 54 filaments of diameter 0.83 mm manufactured by Sam Dong Co., Ltd, have been subjected to twisting, drawing and rolling and measurements at low temperatures. R(T), I–V characteristics, critical currents and stress/strain tolerances of these wires were analyzed. Low reduction of critical current (⩽10%) by twisting between 50 mm and 12.5 mm was observed, especially for the wire with 54 filaments, which also showed the best strain tolerance to tension, ∼0.43% at 4.2 K. The engineering current density of the 18-filament wire was decreased by 56% by drawing from 0.83 mm to 0.4 mm, but improved by ∼24% by rolling from 0.83 mm to 0.64 mm. A small uninsulated coil was made from wire flattened from 0.83 mm to 0.64 mm by the wind and react process, resulting in a very high winding packing factor of 0.91 and also a high winding current density of 104 A cm−2 at B ⩽ 5.6 T. The presented properties are interesting for possible applications of these MgB2 wires in DC windings.
A practical guide to electromagnetically induced transparency in atomic vapor
Authors: Finkelstein Ran , Bali Samir , Firstenberg Ofer , Novikova Irina
Published: February 2023

This tutorial introduces the theoretical and experimental basics of electromagnetically induced transparency (EIT) in thermal alkali vapors. We first give a brief phenomenological description of EIT in simple three-level systems of stationary atoms and derive analytical expressions for optical absorption and dispersion under EIT conditions. Then we focus on how the thermal motion of atoms affects various parameters of the EIT system. Specifically, we analyze the Doppler broadening of optical transitions, ballistic versus diffusive atomic motion in a limited-volume interaction region, and collisional depopulation and decoherence. Finally, we discuss the common trade-offs important for optimizing an EIT experiment and give a brief ‘walk-through’ of a typical EIT experimental setup. We conclude with a brief overview of current and potential EIT applications.
A study on the mechanical and antimicrobial properties of biomimetic shark skin fabrics with different denticle size via 3D printing technology
Authors: Wen Jiayi , Prawel David , Li Yan Vivian
Published: February 2023

Previous studies have shown that biomimetic shark skin fabrics can reduce water drag and increase swimming speed. It was also known that small denticles on shark skin surfaces promoted high water drag reduction. The smallest size of 3D printed denticles on a biomimetic shark skin fabric previously reported was about 2mm, which was still larger than the denticles on shark skin found in nature (100 – 500 µm). In this study, small denticles ranging from 0.65mm to 1.30mm were fabricated to decorate on a smooth film using a Form3 3D printer, resulting in biomimetic shark skin fabrics. The effect of denticle size on mechanical properties (stiffness, Young’s modulus, tensile strength, and breaking elongation) and antimicrobial properties of the biomimetic shark skin fabrics were evaluated to assess the applications in functional clothing. The results suggested that when the size of the denticles was decreased, the stiffness of the fabrics was increased. The tensile strength and the breaking elongation of the fabric with 1.04mm denticles were larger than those of fabric materials used in commercial swimwear. In antimicrobial testing, the shark skin fabrics with 0.65mm and 1.04mm denticles were found to be less susceptible to bacterial attachment, suggesting great potential for functional clothing applications.
A multi-task and multi-channel convolutional neural network for semi-supervised neonatal artefact detection
Authors: Hermans Tim , Smets Laura , Lemmens Katrien , Dereymaeker Anneleen , Jansen Katrien , Naulaers Gunnar , Zappasodi Filippo , Van Huffel Sabine , Comani Silvia , De Vos Maarten
Published: February 2023

Objective. Automated artefact detection in the neonatal electroencephalogram (EEG) is crucial for reliable automated EEG analysis, but limited availability of expert artefact annotations challenges the development of deep learning models for artefact detection. This paper proposes a semi-supervised deep learning approach for artefact detection in neonatal EEG that requires few labelled data by training a multi-task convolutional neural network (CNN). Approach. An unsupervised and a supervised objective were jointly optimised by combining an autoencoder and an artefact classifier in one multi-output model that processes multi-channel EEG inputs. The proposed semi-supervised multi-task training strategy was compared to a classical supervised strategy and other existing state-of-the-art models. The models were trained and tested separately on two different datasets, which contained partially annotated multi-channel neonatal EEG. Models were evaluated using the F1-statistic and the relevance of the method was investigated in the context of a functional brain age (FBA) prediction model. Main results. The proposed multi-task and multi-channel CNN methods outperformed state-of-the-art methods, reaching F1 scores of 86.2% and 95.7% on two separate datasets. The proposed semi-supervised multi-task training strategy was shown to be superior to a classical supervised training strategy when the amount of labels in the dataset was artificially reduced. Finally, we found that the error of a brain age prediction model correlated with the amount of automatically detected artefacts in the EEG segment. Significance. Our results show that the proposed semi-supervised multi-task training strategy can train CNNs successfully even when the amount of labels in the dataset is limited. Therefore, this method is a promising semi-supervised technique for developing deep learning models with scarcely labelled data. Moreover, a correlation between the error of FBA estimates and the amount of detected artefacts in the corresponding EEG segments indicates the relevance of artefact detection for robust automated EEG analysis.
High Performance Analysis, Today and Tomorrow
Authors: Bendavid Josh
Published: February 2023

The unprecedented volume of data and Monte Carlo simulations at the HL-LHC will pose increasing challenges for data analysis both in terms of computing resource requirements as well as ”time to insight”. Discussed are the evolution and current state of analysis data formats, software, infrastructure and workflows at the LHC, and the directions being taken towards fast, efficient, and effective physics analysis at the HL-LHC.