bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the asymmetric chemistry in the disk around the young star HD 142527
Authors: Temmink M. , Booth A. S. , van der Marel N. , van Dishoeck E. F.
Published: April 2023

The atmospheric composition of planets is determined by the chemistry of the disks in which they form. Studying the gas-phase molecular composition of disks thus allows us to infer what the atmospheric composition of forming planets might be. Recent observations of the IRS 48 disk have shown that (asymmetric) dust traps can directly impact the observable chemistry through (radial and vertical) transport and the sublimation of ices. The asymmetric HD 142527 disk provides another good opportunity to investigate the role of dust traps in setting the disk’s chemical composition. In this work we use archival ALMA observations of the HD 142527 disk to obtain a molecular inventory that is as large as possible in order to investigate the possible influence of the asymmetric dust trap on the disk’s chemistry. We present the first ALMA detections of [C I],13C18O, DCO+, H2CO, and additional transitions of HCO+and CS in this disk. In addition, we present upper limits for non-detected species such as SO and CH3OH. For the majority of the observed molecules, a decrement in the emission at the location of the dust trap is found. For the main CO isotopologues, continuum oversubtraction is the likely cause of the observed asymmetry, while for CS and HCN we propose that the observed asymmetries are likely due to shadows cast by the misaligned inner disk. As the emission of the observed molecules is not co-spatial with the dust trap, and no SO or CH3OH is found, thermal sublimation of icy mantles does not appear to play a major role in changing the gas-phase composition of the outer disk in HD 142527 disk. Using our observations of13C18O and DCO+and a RADMC-3D model, we determine the CO snowline to be located beyond the dust traps, favouring cold gas-phase formation of H2CO rather than the hydrogenation of CO-ice and subsequent sublimation.
Exploring magnetic field properties at the boundary of solar pores: A comparative study based on SDO-HMI observations
Authors: Campos Rozo J. I. , Vargas Domínguez S. , Utz D. , Veronig A. M. , Hanslmeier A.
Published: April 2023

Context. The Sun’s magnetic fields play an important role in various solar phenomena. Solar pores are regions of intensified magnetic field strength compared to the surrounding photospheric environment, and their study can help us better understand the properties and behaviour of magnetic fields in the Sun. In this work, we investigate the properties of magnetic fields on the boundaries of solar pores, specifically focusing on the evolution of the vertical magnetic field.

Aims. Up to now, there exists only a single study on magnetic field properties at the boundary region of a pore. Therefore, the main goal of this work is to increase the statistics of magnetic properties determining the pore boundary region. To this aim, we study the change of the vertical magnetic field on the boundaries of six solar pores and their time evolution.

Methods. We analyse six solar pores using data from the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory. We apply image processing techniques to extract the relevant features of the solar pores and determine the boundary conditions of the magnetic fields. For each pore, the maximal vertical magnetic field is determined, and the obtained results are compared with the above-mentioned previous study.

Results. We find the maximal vertical magnetic field values on the boundaries of the studied solar pores to range from 1400 G to 1600 G, with a standard deviation between 7.8% and 14.8%. These values are lower than those reported in the mentioned preceding study. However, this can be explained by differences in spatial resolution as well as the type of data we used. For all the pores, we find that the magnetic inclination angle lies in a range of 30 ± 7°, which is consistent with the idea that the magnetic field configuration in solar pores is mainly vertical.

Conclusions. The vertical magnetic field is an important factor in determining the boundary of solar pores, and it plays a more relevant role than the intensity gradient. The obtained information will be useful for future studies on the formation and evolution of magnetic structures of the Sun. Additionally, this study highlights the importance of high spatial resolution data for the purpose of accurately characterising the magnetic properties of solar pores. Overall, the findings of this work contribute to the understanding of the magnetic field properties of the Sun and will be crucial for improving models of solar dynamics and magnetic flux emergence.
Simultaneous Determination of nicotinamide, kojic acid, Tranexamic acid, raspberry glycoside, azelaic acid, magnesium ascorbate phosphate and β-Arbutin in whitening cosmetics by UPLC-MS/MS
Authors: Zou Xiao , Yan Lixiu , Luo Xiaofang , Wang Enting , Zhang Mingjuan , Huang Wuping , Li Wulin , Tong Lanyan
Published: May 2023

A UPLC-MS/MS method was developed for simultaneous determination of 7 whitening ingredients: nicotinamide, kojic acid, Tranexamic acid, raspberry glycoside, azelaic acid, magnesium ascorbate phosphate and β-Arbutin in cosmetics. The whitening active components were extracted from cosmetics by supersonic extraction with sodium chloride and dichloromethane to disperse the sample, and supersonic extraction with 0.015 mol/L potassium dihydrogen phosphate solution purified by HLB solid phase extraction column, scanned and detected by electrospray ionization source with positive and negative ion alternate scanning mode and multiple reaction monitoring mode. The results showed that the whitening active ingredients were separated within 3 minutes, with a good linear relationship (R>0.999), and the detection limit was 0.10mg/kg~0.75mg/kg. The recoveries (n=6) were 78.84%-104.85%, and the RSDs were 0.24%-11.35%. This method is suitable for the rapid determination of whitening active ingredients in cosmetics.
Research and Development of Intelligent Drying Detection Technology for Machine-Made Sand
Authors: Jia Shaoying , Zhang Xiong , Lu Yelin
Published: May 2023

This paper aims to develop a high precision variable dielectric constant capacitor detector for mechanical sand water content testing. The non-contact on-line test method can effectively solve the problems of low repeatability of test data, large hysteresis error and poor linearity due to the non-uniform water content. In terms of hardware, CAV444 is a high-precision integrated chip, which matches the corresponding test circuit. The system communicates with PC through serial interface and implements the man-machine interface of PC system based on VS. Secondly, the distribution map method is used to measure the water content of machine-made sand, and the error analysis is carried out. The test shows that the output of the capacitive hygrometer is 0-5 V. The delay time should not exceed 0.15%. The repetition rate was within 0.33%. The measurement accuracy of this method is less than 3.52%.
Design of a NC machine tool for machining that is easy to change cutting tools
Authors: Wan Zhiqiang , Zhang Qingqing
Published: May 2023

A CNC machine tool for machining designed to facilitate the replacement of cutting tools includes a workbench, a motor and a hydraulic cylinder. The inner bearing of the workbench is connected with a rotating rod, the outer key of the rotating rod is connected with a half gear, and the output end of the motor is connected with the lower end of the rotating rod. The CNC machine tool for machining, which is convenient for replacing cutting tools, realizes the linkage between the cutting tool body and the adjusting gear by using the tooth block, and drives the adjusting rod to move by using the rotation of the screw rod to adjust the position between the pawl and the ratchet teeth. The rotation of the adjusting gear is limited by using the pawl and the ratchet teeth, so as to lock the cutting tool body and quickly disassemble and install the cutting tool body.
Electronic Properties of MTe2/AsI3(M=Mo and W) Van der Waals Heterostructures
Authors: Liu Zixiang , Wang Zhiguo
Published: May 2023

Two dimensional (2D) materials with unique physical or chemical prperties has triggered worldwide interest in the fields of material science, condensed matter physics, and devices physics. Vertically stacking different 2D materials enables the creation of a large variety of van der Waals heterostructures. The van der Waals heterostructures robust the merits of the 2D materials electronic prperties. Using density functional theory calculations, the electronic structure of MTe2/AsI3(M=Mo and W) Van der Waals heterostructures are investigated in this work. The results show by stacking MTe2(M=Mo and W) and AsI3 vertically, a strongly binding vdW heterostructure with a type-II band alignment can be formed, which gives expectation of high multifunctional electronic performance. This theoretical study provides vital insights of 2D materials and their heterostructures which could be potential candidates for future nanoelectronic applications.
Design of double-layered framed plate with equivalent impedance
Authors: Li Zhao , Zhang Hao , Niu Qingyong , Wang Peng , Cao Xiaoming
Published: May 2023

To get clear the vibration mechanism of sandwith shell using the experiment method, a double-layered plate is designed for the sandwich shell by matching the equivalent impedance. Numerical analysis is conducted, and In 10Hz-4000Hz, the differenceof impedance from double-layered plate and sandwich shell should be less than 10%. A new design is given for the double-layered plate, and which is quite simple for construction. Then, the double-layered plate could be applied to conduct series vibration tests to get clear the influence of sandwich core material on structural vibration, while it could also reduce the costs of money and construction time.
Design and mechanical analysis of shear thickening fluid/polyurethane composite sandwich
Authors: Cong Hua , Zhao Mingmei , Zhang Jinqiu , Liu Yile
Published: May 2023

In this paper, high density rigid polyurethane foam is used as sandwich skeleton and shear thickening fluid as material core. A shear thickening fluid/polyurethane sandwich structure with light impact resistance was designed and fabricated. High strain rate impact test was carried out. It was found that STF-2/PU reached the peak load of 4978N in 13 ms after receiving 20 J impact energy, and the energy absorption ratio was as high as 43%. The shear thickening fluid/polyurethane honeycomb sandwich foam prepared by secondary foaming process has stable structure and can effectively absorb impact energy to achieve good protection effect.
Graphs with small or large Roman {3}-domination number
Authors: Ebrahimi Nafiseh , Abdollahzadeh Ahangar Hossein , Chellali Mustapha , Sheikholeslami Seyed Mahmoud
Published: April 2023

For an integer k ≥ 1, a Roman {k}-dominating function (R{k}DF) on a graph G = (V, E) is a function f : V → {0, 1, …, k} such that for every vertex v ∈ V with f(v) = 0, ∑u∈N(v) f(u) ≥ k, where N(v) is the set of vertices adjacent to v. The weight of an R{k}DF is the sum of its function values over the whole set of vertices, and the Roman {k}-domination number γ{kR}(G) is the minimum weight of an R{k}DF on G. In this paper, we will be focusing on the case k = 3, where trivially for every connected graphs of order n ≥ 3, 3 ≤ γ{kR}(G) ≤n. We characterize all connected graphs G of order n ≥ 3 such that γ{3R}(G) ∈ {3, n − 1, n}, and we improve the previous lower and upper bounds. Moreover, we show that for every tree T of order n ≥ 3, γ{3R}(T) ≥ γ(T) + 2, where γ(T) is the domination number of T, and we characterize the trees attaining this bound.
The Impact of the COVID-19 Pandemic on the Care of Women Experiencing Abortion in a University Hospital in Brazil
Authors: Dantas Priscilla Brenda Fonseca , Trabach Carolina Braga , Junqueira Aline Aparecida , Nunes Carina Cordeiro , Veiga-Junior Nelio Neves , Baccaro Luiz Francisco
Published: April 2023

Objective To evaluate the impact of the coronavirus disease 2019 (COVID-19) pandemic on the care of patients with miscarriage and legal termination of pregnancy in a university hospital in Brazil.

Methods A cross-sectional study of women admitted for abortion due to any cause at Hospital da Mulher Prof. Dr. J. A. Pinotti of Universidade Estadual de Campinas (UNICAMP), Brazil, between July 2017 and September 2021. Dependent variables were abortion-related complications and legal interruption of pregnancy. Independent variables were prepandemic period (until February 2020) and pandemic period (from March 2020). The Cochran-Armitage test, Chi-squared test, Mann-Whitney test, and multiple logistic regression were used for statistical analysis.

Results Five-hundred sixty-one women were included, 376 during the prepandemic period and 185 in the pandemic period. Most patients during pandemic were single, without comorbidities, had unplanned pregnancy, and chose to initiate contraceptive method after hospital discharge. There was no significant tendency toward changes in the number of legal interruptions or complications. Complications were associated to failure of the contraceptive method (odds ratio [OR] 2.44; 95% confidence interval [CI] 1.23–4.84), gestational age (OR 1.126; 95% CI 1.039–1.219), and preparation of the uterine cervix with misoprostol (OR 1.99; 95% CI 1.01–3.96).

Conclusion There were no significant differences in duration of symptoms, transportation to the hospital, or tendency of reducing the number of legal abortions and increasing complications. The patients' profile probably reflects the impact of the pandemic on family planning.
Age and Type of Delivery as Risk Indicators for Maternal Mortality
Authors: Oliveira Isabella Mantovani Gomes Dias de , Fonseca Emílio Prado da , França Fabiana Mantovani Gomes , Cortellazzi Karine Laura , Pardi Vanessa , Pereira Antonio Carlos , Tagliaferro Elaine Pereira da Silva
Published: April 2023

Objective: This study assessed maternal mortality (MM) and related factors in a large-sized municipality in the Southeastern region of Brazil (Campinas, São Paulo) during the period 2000-2015.

Methods: This study consisted of two phases: 1. An analytical nested case-control phase that assessed the impact of individual and contextual variables on MM; and 2. an ecological phase designed to contextualize maternal deaths by means of spatial analysis. The case group consisted of all maternal deaths (n = 87) and the control group consisted of 348 women who gave birth during the same period. Data analysis included descriptive statistics, association, and multiple logistic regression (MLR) tests at p < 0.05 as well as spatial analysis.

Results: Maternal Mortality Ratio was 37 deaths per 100.000 live births. Deaths were dispersed throughout the urban territory and no formation of cluster was observed. MLR showed that pregnant women aged ≥ 35 years old (OR = 2.63) or those with cesarean delivery (OR = 2.51) were more prone to maternal death.

Conclusion: Maternal deaths were distributed dispersedly among the different socioeconomic levels and more prone to occur among older women or those undergoing cesarean deliveries.
Predicting loss aversion behavior with machine-learning methods
Authors: Saltık Ömür , Rehman Wasim ul , Söyü Rıdvan , Değirmen Süleyman , Şengönül Ahmet
Published: April 2023

This paper proposes to forecast an important cognitive phenomenon called the Loss Aversion Bias via Hybrid Machine Learning Models. One of the unique aspects of this study is using the reaction time (milliseconds), psychological factors (self-confidence scale, Beck’s hopelessness scale, loss-aversion), and personality traits (financial literacy scales, socio-demographic features) as features in classification and regression methods. We found that Random Forest was superior to other algorithms, and when the positive spread ratio (between gain and loss) converged to default loss aversion level, decision-makers minimize their decision duration while gambling, we named this phenomenon as “irresistible impulse of gambling”.
Topological energy of networks
Authors: Nie Chun-Xiao
Published: April 2023

Energy is an important network indicator defined by the eigenvalues of an adjacency matrix that includes the neighbor information for each node. This article expands the definition of network energy to include higher-order information between nodes. We use resistance distances to characterize the distances between nodes and order complexes to extract higher-order information. Topological energy ( T E), defined by the resistance distance and order complex, reveals the characteristics of the network structure from multiple scales. In particular, calculations show that the topological energy can be used to distinguish graphs with the same spectrum well. In addition, topological energy is robust, and small random perturbations of edges do not significantly affect the T E values. Finally, we find that the energy curve of the real network is significantly different from that of the random graph, thus showing that T E can be used to distinguish the network structure well. This study shows that T E is an indicator that distinguishes the structure of a network and has some potential applications for real-world problems.
Topological energy harvesting of surface acoustic waves in a phononic crystal slab with periodic stubbed surface
Authors: Li Jing , Li Pan , Qi Yajuan , Zhao Degang
Published: April 2023

In this paper, we demonstrate energy harvesting of surface acoustic waves (SAWs) via topological interface states in a two-dimensional phononic crystal (PC) with the periodic arrangement of bar-like locally resonant units on its surface. The system can produce pure SAW bands in the subwavelength realm due to bar oscillation. Both transverse and longitudinal vibrations of the stubbed bar can selectively couple to the intrinsic SAWs in the PC slab. Subsequently, through constructing the typical Su–Schrieffer–Heeger model, we analyze the topological properties of zone-folding-induced SAW bands with transverse and longitudinal vibration characteristics, respectively. When two arrays with distinct topological bandgaps are spliced together, topological interface states will appear. Topological energy harvesting of SAWs with two different vibration characteristics is finally achieved in one structure. Our study expands the applicability of topological interface states for SAW in a compacted platform, such as polarization selection or sensing.
Electromagnetic forces on a discrete concentrator under time-harmonic illumination
Authors: Chaumet Patrick C. , Guenneau Sébastien R. L.
Published: April 2023

We study electromagnetic forces and torques experienced on both perfect and discretized transformation-based concentrators, under time-harmonic illumination. The effect of the concentration is investigated in both cases and compared to the case of a perfect cloak. The effect of a Lorentz dispersion model on the optical force and torque is also investigated, and the force experienced by a dielectric particle located at the center of the concentrator is studied.
Characteristics and development of damage in the interface of
polyimide multilayer films under a repetitive-frequency-pulsed
voltage
Authors: Yu Menghan , Yang Lanjun , Xiao Xinyan , Zhang Hongtao
Published: April 2023

To study the initiation and development of interfacial electrical damage in multi-layer dielectrics, an aging test of 3-layer polyimide films was conducted under pulsed voltage with a repetitive frequency of 500 Hz and a maximal amplitude of 30 kV. The variation in the damage morphology with the number of applied pulses was analyzed by a statistical method. The circuit current and partial discharge at different aging stages was measured, and the Fourier transform infrared spectrum analysis results of the aged and unaged sample regions were compared. The results demonstrate that the partial discharge in the dielectric interface gap, which is unavoidable in manufacturing, is the main cause of damage. It initiates from the interface and grows into the interior of the dielectric with the application of pulses. When there are no macroscopic defects on dielectric films, damage presents a punctiform morphology. The damage process can be divided into the following three stages: surface roughening damage, steady growth stage of damage points, and pre-breakdown stage. Differing from dielectrics without macroscopic defects, dielectrics with original void defects present transverse dendritic damage channels that initiate from the edge of the defect.
Doped HfO2-based ferroelectric-aided charge-trapping effect in MFIS gate stack of FeFET
Authors: Zhang Bao , Hong Peizhen , Hou Jingwen , Huo Zongliang , Ye Tianchun
Published: April 2023

The ferroelectric field effect transistor (FeFET) is a very promising candidate for low-power and non-volatile memory. However, the co-existing effect of ferroelectric polarization and interface charge trapping in the FeFETs is demonstrated and many efforts have been made to eliminate this charge-trapping effect, which is usually treated as a deleterious effect. In contrast, we have found that the charge-trapping effect can play a dominant role in ferroelectric gates. In this work, we have verified that the charge-trapping effect of the ferroelectric/insulator interface could induce a memory window as the main physical mechanism in the TiN/Hf0.5Zr0.5O2/SiO2/p-Si (MFIS) structure, in which the ferroelectric characteristics of HZO thin films was verified through a reverse-grown MFIS structure. We also demonstrated that 2.5 nm SiO2 is optimal for the charge tunneling effect and the device has the largest memory window. Moreover, in order to enlarge the memory window of MFIS capacitors, we utilized the stress-enhanced ferroelectric polarization characteristics of Hf0.5Zr0.5O2 to improve the charge-trapping effect. Such a finding demonstrates that the ferroelectric-aided charge-trapping devices are potential to be used in non-volatile memories.
Interphase-assisted suppression of electrode polarization in nanoparticulate-elastomeric composites
Authors: Barhoumi Meddeb A. , Ounaies Z.
Published: April 2023

The electrical properties of polymer nanocomposites are governed by the behavior of the internal charges. In particular, the interphase around the nanoparticles strongly influences the distribution and mobility of charge carriers within the nanocomposites, which, in turn, impacts the performance of these materials. In this work, we probe the internal charge behavior in the presence of nanoparticles with a focus on the low-frequency regime using a suite of techniques. By investigating the depolarizing currents and the dependence of the dielectric properties on the frequency and temperature, we demonstrate that the interphases redistribute the space charges, increase their trap depth, and suppress the electrode polarization in an elastomeric nanocomposite. Additionally, we study the effect of the nanoparticle content on the dielectric behavior by comparing the internal charge behavior of 1, 2, and 4 vol. % nanocomposites. At only 4 vol. % loading, the mobility of charge carriers is effectively limited, leading to lower dc conductivity compared to the unfilled elastomer, and 1 and 2 vol. % nanocomposites. These findings are based on the model materials used in this study, TiO2 nanoparticles and polydimethylsiloxane, and can be extended to other nanoparticulate-filled elastomer composites to design lightweight dielectrics, actuators, and sensors with improved capabilities. Judicious manipulation of interfacial phenomena in polymer nanocomposites—especially those with a dilute content of nanoparticles—provides a promising path forward for the design of materials with exceptional electrical and other physical properties.
A low-magnetic packaging for a distributed Bragg reflector laser diode chip for atomic sensor applications
Authors: Kim M. M. , Lee S. , Yim S. H. , Yoon J. H.
Published: April 2023

We implement a distributed Bragg reflector (DBR) laser diode (LD) package with low-magnetic field generation. The package consists of a commercial 795 nm DBR LD chip, a thermo-electric cooler (TEC), a thermistor, a flexible printed circuit board (FPCB) which cancels the magnetic field emitted by the TEC current flow, and a non-magnetic aluminum case. We confirm that the magnetic dipole moment of our low-magnetic package body is about three orders of magnitude smaller than that of a commercial DBR laser package. Moreover, it is shown that our compensating FPCB, the effectiveness of which is supported by computer simulations, reduces the magnetic field magnitude by a factor of 2.2. The FPCB also reduces the magnetic field gradient emitted by the TEC current flow so that gradient-induced spin relaxations are suppressed in applications. A portable optically pumped atomic magnetometer (OPAM) utilizing two low-magnetic packages as light sources is reported as an application of the package and shows a 0.30 pT/Hz1/2 level magnetic sensitivity at a 69 μT external magnetic field; in contrast, the OPAM utilizing the commercial packages showed a magnetic sensitivity of 0.87 pT/Hz1/2.
Self-assembling peptide biomaterials: Insights from spontaneous and enhanced sampling molecular dynamics simulations
Authors: Williams-Noonan Billy J. , Kamboukos Alexa , Todorova Nevena , Yarovsky Irene
Published: April 2023

Peptide self-assembly is the process by which peptide molecules aggregate into low dimensional (1D, 2D) or 3D ordered materials with potential applications ranging from drug delivery to electronics. Short peptides are particularly good candidates for forming supramolecular assemblies due to the relatively simple structure and ease of modulating their self-assembly process to achieve required material properties. The experimental resolution of fibrous peptide-based nanomaterials as 3D atomic coordinates remains challenging. For surface-mediated peptide assembly in particular, it is typically not feasible to resolve multiple conformationally distinct surface bound peptide structures by experiment. The mechanisms of peptide self-assembly also remain elusive due to the interchange of complex interactions and multiple time and length scales involved in the self-assembly process. Peptide self-assembly in solution, or mediated by surfaces, is driven by specific interactions between the peptides and water, competing interactions within the peptide and/or between peptide aggregate units and, in the latter case, an interplay of the interactions between peptides and solvent molecules for adsorption onto a proximal surface. Computational methodologies have proven beneficial in elucidating the structures formed during peptide self-assembly and the molecular mechanisms driving it, and hence have scope in facilitating the development of functional peptide-based nanomaterials for medical or biotechnological applications. In this perspective, computational methods that have provided molecular insights into the mechanisms of formation of peptide biomaterials, and the all-atom-resolved structures of peptide assemblies are presented. Established and recently emerged molecular simulation approaches are reviewed with a focus on applications relevant to peptide assembly, including all-atom and coarse-grained “brute force” molecular dynamics methods as well as the enhanced sampling methodologies: umbrella sampling, steered and replica exchange molecular dynamics, and variants of metadynamics. These approaches have been shown to contribute all-atom details not yet available experimentally, to advance our understanding of peptide self-assembly processes and biomaterial formation. The scope of this review includes a summary of the current state of the computational methods, in terms of their strengths and limitations for application to self-assembling peptide biomaterials.
Converging-guiding-track design enables 100% growth deployment rate of ultrathin monocrystalline silicon nanowire channels
Authors: Qian Wentao , Liang Yifei , Wang Junzhuan , Liu Zongguang , Xu Jun , Yu Linwei
Published: April 2023

A low temperature catalytic growth of orderly ultrathin silicon nanowires (SiNWs) is desirable for the construction of monolithic 3D stacked electronics but usually suffers a large diameter fluctuation and a low growth deployment rate (GDR). In this work, the ultra-confined growth dynamics of in-plane solid–liquid–solid SiNWs within narrow groove tracks has been systematically investigated, and a converging-guiding-track strategy is proposed and testified to accomplish 100% GDR of ultra-dense and uniform SiNW array, with diameter and spacing of only Dnw = 22.5±3.5 nm and 25 nm, respectively. Despite a low temperature growth at 350 °C, the SiNWs are found to be all monocrystalline and Si⟨100⟩ oriented, while prototype Schottky barrier tunneling field effect transistors built on the SiNW channels demonstrate a high Ion/off ratio and subthreshold swing of >105 and 197 mV dec−1. This new strategy complements a long-missing key capability of catalytic growth approach to serve a reliable integration technology of ultrafine high quality 1D c-Si channels, without the need of preexisting wafer substrate, for a wide range of 3D electronics, neuromorphic, and logic-in-memory functionalities.
Study of hydrogenation with electron injection for TOPCon solar cells with different tunneling oxide layers
Authors: Yu Leifei , Xi Xi , Liu Guilin , Chen Liping , Shao Jianbo , Zhou Yunlong
Published: April 2023

In order to further improve the photovoltaic conversion efficiency of tunnel oxide passivated contact (TOPCon) solar cells, the hydrogenation with electron injection (HEI) technique on TOPCon solar cells with different processes for preparing tunneling SiOx layers was investigated. The experimental results showed that the conversion efficiency enhancement of TOPCon solar cells with a tunneling SiOx layer prepared by a N2O plasma oxidation method (PO method) was lower than that of the cells prepared by an indirect thermal oxidation method (TO method) under the same HEI treatment conditions. Further studies proved that the improvement effect after HEI treatment was closely related to the denseness of the tunneling SiOx layer: HEI treatment for TOPCon solar cells with a low dense tunneling SiOx layer (TO method) requires higher temperature, higher current, and longer time to achieve a better improvement, while the HEI parameters of cells with a high dense tunneling oxide layer (PO method) need to be readjusted. By optimizing the HEI parameters for cells prepared by the PO method, the power conversion efficiency (PCE) of the cells was finally improved by 0.098%abs. The PCE was improved from the original negative growth to a level close to that of the TOPCon cells prepared by the TO method. This result provided an improved process flow to further increase the efficiency of TOPCon solar cells.
MXene-functionalized KNN dielectric nanofillers incorporated in PVA nanofibers for high-performance triboelectric nanogenerator
Authors: Sardana Sagar , Saddi Rishiwer , Mahajan Aman
Published: April 2023

The low surface charge density and consequent unsatisfactory energy conversion efficiency of nanogenerators hinder their capacious utility toward the emerging field of wearable electronics. The strategy of introducing dielectric fillers into a polymer matrix attempts to improve dielectric constant and, thereby, to enhance surface charge density but can hardly yield sufficient energy conversion efficiency. Herein, we report a high performance flexible and compressible triboelectric nanogenerator (FC-TENG) based on a lead-free dielectric material, potassium sodium niobate (KNN), embedded with Ti3C2Tx MXene fillers, blended into poly-vinyl alcohol (PVA) using an electrospinning technique. The role of MXene in dielectric functionalization is to promote the interfacial polarization effect by forming micro-capacitor structures or percolation systems and, thereby, to endow high charge-inducing and charge-trapping capabilities. As a result, the prepared 4 vol. % MXene loaded KNN/PVA nanofibers achieve a higher dielectric constant/dielectric loss factor, which leads to enhanced energy conversion efficiency of FC-TENGs with a maximum power density of ∼2780 mW/cm2. In addition, the selected device was employed into shoe-insoles to demonstrate its ability of capturing biomechanical energy, which reveals its potential to be utilized as a wearable power-source for next generation devices.
Transient pressure-driven electrokinetic slip flow and heat transfer through a microannulus
Authors: Zhan Qinjian , Deng Shuyan
Published: April 2023

To guarantee the transporting efficiency of microdevices associated with fluid transportation, mixing, or separation and to promote the heat transfer performance of heat exchangers in microelectronics, the hydrodynamic behaviors at the unsteady state as well as the thermal characteristics at the steady state in a pressure-driven electrokinetic slip flow through a microannulus are studied. To present a more reliable prediction, the slip phenomenon at walls is incorporated. The Cauchy momentum equation applicable to all time scales is analytically solved by the integral transform method; thereby, the physical picture of how the flow is initiated and accelerated to the steady state is provided. The energy equation and entropy generation for the steady flow are numerically solved. Consequently, the temperature profile, heat transfer rate, and entropy generation rate are computed at different electrokinetic widths, slip lengths, Joule heating parameters, and Brinkman numbers; thereby, the coupling effect of the slip hydrodynamics, annular geometry, viscous dissipation, and Joule heating on thermal behaviors is explored. The unsteady flow takes a longer time to achieve the steady state for a smaller radius ratio. The slip length not only accelerates the flow but also alters the velocity and temperature profiles. Compared to the outer one, the inner slip length plays a more significant role on the entropy generation rate. The relevant discussion can serve as a theoretical guide for the operation and thermal management of flow actuation systems related to annular geometries.
Spin noise in Er3+ single-ion magnets surrounded by ferromagnetic microparticles
Authors: Morgunov R. B. , Allayarov R. S. , Kunitsyna E. I. , Koplak O. V.
Published: April 2023

Ferromagnetic microparticles significantly affect spin relaxation in the Er3+ single-ion magnet sandwiched in a composite material. The balance of thermal spin noise corresponding to Orbach, Raman, quantum tunneling, and direct relaxation channels is shifted in Er3+ complexes under the influence of surrounding ferromagnetic matrix. There are two competing sources of the electron spin noise controlled by ferromagnetic media. First, internal residual magnetic field delays spin relaxation in the Er3+ complexes due to the Zeeman interaction of the Er3+ spin even in the absence of external magnetic field. Second, chemical bonding between the Er 4d shell and the O 1s shell accelerates magnetic relaxation in the Er3+ ions on the surface of microparticles. Significance of these results is that composite media can be sliced into small elements with a variable frequency of spin noise depending on individual magnetization programmed within each element.
Atomic-scale in situ observation of electron beam and heat induced crystallization of Ge nanoparticles and transformation of Ag@Ge core-shell nanocrystals
Authors: Qi Xiao , Bustillo Karen C. , Kauzlarich Susan M.
Published: April 2023

Crystallization of amorphous materials by thermal annealing has been investigated for numerous applications in the fields of nanotechnology, such as thin-film transistors and thermoelectric devices. The phase transition and shape evolution of amorphous germanium (Ge) and Ag@Ge core–shell nanoparticles with average diameters of 10 and 12 nm, respectively, were investigated by high-energy electron beam irradiation and in situ heating within a transmission electron microscope. The transition of a single Ge amorphous nanoparticle to the crystalline diamond cubic structure at the atomic scale was clearly demonstrated. Depending on the heating temperature, a hollow Ge structure can be maintained or transformed into a solid Ge nanocrystal through a diffusive process during the amorphous to crystalline phase transition. Selected area diffraction patterns were obtained to confirm the crystallization process. In addition, the thermal stability of Ag@Ge core–shell nanoparticles with an average core of 7.4 and a 2.1 nm Ge shell was studied by applying the same beam conditions and temperatures. The results show that at a moderate temperature (e.g., 385 °C), the amorphous Ge shell can completely crystallize while maintaining the well-defined core–shell structure, while at a high temperature (e.g., 545 °C), the high thermal energy enables a freely diffusive process of both Ag and Ge atoms on the carbon support film and leads to transformation into a phase segregated Ag–Ge Janus nanoparticle with a clear interface between the Ag and Ge domains. This study provides a protocol as well as insight into the thermal stability and strain relief mechanism of complex nanostructures at the single nanoparticle level with atomic resolution.
Trap-integrated superconducting nanowire single-photon detectors with improved rf tolerance for trapped-ion qubit state readout
Authors: Hampel Benedikt , Slichter Daniel H. , Leibfried Dietrich , Mirin Richard P. , Nam Sae Woo , Verma Varun B.
Published: April 2023

State readout of trapped-ion qubits with trap-integrated detectors can address important challenges for scalable quantum computing, but the strong radio frequency (rf) electric fields used for trapping can impact detector performance. Here, we report on NbTiN superconducting nanowire single-photon detectors (SNSPDs) employing grounded aluminum mirrors as electrical shielding that are integrated into linear surface-electrode rf ion traps. The shielded SNSPDs can be operated at applied rf trapping potentials of up to 54   V peak at 70 MHz and temperatures of up to 6 K, with a maximum system detection efficiency of 68%. This performance should be sufficient to enable parallel high-fidelity state readout of a wide range of trapped ion species in a typical cryogenic apparatus.
A highly sensitive broadband superconducting thermoelectric single-photon detector
Authors: Paolucci Federico , Germanese Gaia , Braggio Alessandro , Giazotto Francesco
Published: April 2023

We propose a passive single-photon detector based on the bipolar thermoelectric effect occurring in tunnel junctions between two different superconductors thanks to spontaneous electron–hole symmetry breaking. Our superconducting thermoelectric detector (STED) converts a finite temperature difference caused by the absorption of a single photon into an open circuit thermovoltage. Designed with feasible parameters, our STED is able to reveal single photons of frequency ranging from ∼15 GHz to ∼150 PHz depending on the chosen design and materials. In particular, this detector is expected to show values of the signal-to-noise ratio SNR∼15 at ν = 50 GHz when operated at a temperature of 10 mK. Interestingly, this device can be viewed as a digital single-photon detector, since it generates an almost constant voltage VS for the full operation energies. Our STED can reveal single photons in a frequency range wider than four decades with the possibility to discern the energy of the incident photon by measuring the time persistence of the generated thermovoltage. Its broadband operation suggests that our STED could find practical applications in several fields of quantum science and technology, such as quantum computing, telecommunications, optoelectronics, THz spectroscopy, and astro-particle physics.
First direct measurement of electron and positron bunch characteristics at the positron source of the SuperKEKB B-factory
Authors: Suwada Tsuyoshi
Published: April 2023

Electron (e−) and positron (e+) bunch characteristics were directly measured for the first time by using wideband beam monitors (WBMs) and a detection system at the e+ source of the SuperKEKB B-factory. Secondarily generated e− and e+ bunches after the e+-production target were identified in their dynamical capture process at locations of the WBMs under a two-bunch acceleration scheme. The longitudinal and transverse bunch characteristics, the time intervals between the e− and e+ bunches, the bunch lengths, transverse bunch positions, and bunch charges were simultaneously separately measured for each bunch as functions of the capture phase to investigate their dynamical capture process. The results show that quite symmetric behaviors of the e− and e+ bunch characteristics were observed. The new WBMs open up a new window for direct measurements of both e− and e+ bunches during their dynamical capture process and in the optimization procedure of the e+ bunch intensity in multidimensional parameter spaces at any e+ sources.
Anomalous and non-monotonic strain dependent thermal conductivity of typical negative thermal expansion material ScF3
Authors: Tang Zhunyun , Wang Xiaoxia , Li Jin , He Chaoyu , Tang Chao , Wang Huimin , Chen Mingxing , Ouyang Tao
Published: April 2023

It is well known that the lattice thermal conductivity of the vast majority of bulk materials increases under compressive strain and decreases under tensile strain. In this paper, taking the typical negative thermal expansion material ScF3 as an example, we systematically investigate the effect of strain on the phonon transport properties by means of first-principles calculation combined with the Boltzmann transport equation. The results show that the thermal conductivity of ScF3 exhibits an anomalous strain dependence, where the thermal conductivity decreases under compressive strain while increasing as the tensile strain is smaller than −4.2 GPa. When the tensile strain increases further (larger than −4.2 GPa), however, the thermal conductivity of ScF3 decreases with tensile strain, presenting a non-monotonic behavior. Through analyzing the phonon mode information, we demonstrate that such anomalous and non-monotonic strain dependent thermal transport in ScF3 mainly originated from the intrinsic character of the negative Grüneisen parameter (negative thermal expansion). Moreover, the root mean square displacement is also utilized to further demonstrate the variation of phonon anharmonicity and thermal conductivity of ScF3 with strain. The findings shed light on the underlying association between thermal expansion and thermal conductivity and provide a feasible strategy for searching for materials with anomalous strain dependent thermal conductivity.
Stacking fault strengthening in CoCrFeMnNi high-entropy alloy
Authors: Duan Mengye , Fu Tao , Pan Yang , Liu Xuyang , Peng Xianghe
Published: April 2023

The effects of stacking faults (SFs) on the mechanical properties of high-entropy alloys (HEAs) may not be ignored because of the lower or even negative SF energy. Here, we investigated the SF strengthening of CoCrFeMnNi and clarified its potential mechanism. It showed experimentally that the CoCrFeMnNi with more SFs had higher strength and hardness than that with fewer SFs, revealing significant SF strengthening. To gain an insight into such effects, we performed simulations for the mechanical responses of CoCrFeMnNi samples with different plane defects at the atomic scale. The results showed that the strengths of the CoCrFeMnNi samples containing SFs or twin boundaries were higher than that of single crystal ones. Overall, our results suggested that the effects of SFs on the mechanical properties of FCC HEAs could not be ignored, and the atomistic insights into the strengthening mechanism of HEAs we provided would be beneficial to improve the mechanical properties of FCC HEAs.
Dynamic simulation study of the secondary frequency regulation of a 1000 MW thermal power unit assisted by flywheel energy storage
Authors: Lv Zhijia , Liu Xiaolong , Liu Zhongwen , Jiang Zhicheng , Lin Zhao , Zhao Zicheng , Han Xu
Published: April 2023

The rapid development of new energy sources has brought a certain impact on the original power grid structure, accelerated the wear of unit equipment, and affected the stability, safety, and economy of thermal power unit operation, so it is proposed to add an energy storage system to solve the above problems. To analyze the secondary frequency regulation effect of thermal power units assisted by a flywheel energy storage system, a mathematical model of the control strategy on both sides of the boiler, steam turbine, and flywheel permanent magnet synchronous motor is proposed, and a two-regional power grid model is built through MATLAB/Simulink to simulate the frequency regulation effect of units with or without energy storage participation through step disturbance and continuous disturbance, which are 0.045 and 0.023 p.u. MW. Under step disturbance, the frequency fluctuation of the coupled energy storage system changed by 0.025 228 p.u. Hz, the time for the system to return to a steady state was shortened by 5.85 s, the maximum change of the frequency of the system in Region 2 was reduced by 0.025 579 p.u. Hz, and under continuous disturbance, the fluctuation of the output power of the steam turbine in Region 1 was reduced by 0.022 982 p.u. MW. In summary, under the same disturbance conditions in the outside world, the use of flywheel energy storage to assist the frequency regulation of thermal power units can effectively reduce the frequency fluctuation of the system, reduce the fluctuation of the output power of the steam turbine, reduce the loss of mechanical equipment, and extend the service life of the unit to a certain extent.
Experiences of peer messengers as part of a professional accountability culture change program to reduce unprofessional behaviour: a cross-sectional study across eight hospitals
Authors: McMullan Ryan D. , Urwin Rachel , Sunderland Neroli , Churruca Kate , Cunningham Neil , Westbrook Johanna
Published: April 2023

Objective Professional accountability programs are designed to promote professional behaviours between co-workers and improve organisational culture. Peer messengers play a key role in professional accountability programs by providing informal feedback to hospital staff about their behaviour. Little is known about the experiences of messengers. This study examined the experiences of staff who delivered messages to peers as part of a whole-of-hospital professional accountability program called ‘Ethos’. Methods Ethos messengers (EMs) across eight Australian hospitals were invited to complete an online survey. The survey consisted of 17 close-ended questions asking respondents about their experiences delivering messages to peers and their perceptions of the Ethos program. Four open-ended questions asked respondents about rewarding and challenging aspects of being a peer messenger and what they would change about the program. Results Sixty EMs provided responses to the survey (response rate, 41.4%). The majority were from nursing and medical groups (53.4%) and had delivered 1–5 messages to staff (57.7%). Time as an EM ranged from less than 3 months to more than 12 months. A majority had been an EM for more than 12 months (80%; n = 40). Most agreed they had received sufficient training for the role (90.1%; n = 48) and had the skills (90.1%; n = 48), access to support (84.9%; n = 45) and time to fulfil their responsibilities (70.0%; n = 30). Approximately a third (34.9%; n = 15) of respondents indicated that recipients were ‘sometimes’ or ‘never’ receptive to messages. Challenging aspects of the role included organising a time to talk with staff, delivering feedback effectively and communicating with peers who lacked insight and were unable to reflect on their behaviour. Conclusions Skills development for peer messengers is key to ensuring the effectiveness and sustainability of professional accountability programs. Training in how to deliver difficult information and respond to negative reactions to feedback was identified by EMs as essential to support their ongoing effectiveness in their role.