bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of a Hands-On Interventional Radiology Training Course on Radiology Resident's Training: A Single Academic Institution Experience
Authors: Guimbarda Nicholas , Armashi Hashim , Parker William , Freedman Arthur , Elhelf Islam A.S.
Published: September 2023

Purpose The aim of this study was to investigate the outcomes of an instructional hands-on training course that introduces radiology residents to the essential tools and skills needed to perform basic interventional radiology (IR) procedures.

Materials and Methods This study was performed over a single academic year at a single academic institution. A precourse survey was sent to all radiology residents to identify areas of weakness and potential opportunities for improvement. In view of the responses, a hands-on training course was designed to cover the basics of vascular and soft-tissue access, catheters, wires, embolics, and closure devices. The training was provided in a one-to-one setting by a single IR attending over a period of 45 minutes and was concluded with hands-on training on an ultrasound (US) vascular access phantom whenever possible. An anonymous postcourse survey was then distributed and the results were analyzed.

Results The average reported comfort level with basic IR concepts prior to course attendance was 1.7 on a 5-point scale (1 = not comfortable, 5 = very comfortable). This increased to an average of 4 following the course. Ninety-three percent of residents reported they have more confidence getting into the IR suite and assisting in IR procedures following the course. Residents who had an opportunity to train on the US vascular access phantom gave an average response of 4.6 out of 5 to a question of how helpful the experience was in improving their US hand skills (1 = not helpful, 5 = extremely helpful). One hundred percent of responders reported that the course successfully met its goal. Finally, the overall responses were unanimously in favor of continuing the hands-on training course.

Conclusion A personalized, cost-effective, hands-on training course can improve the IR training experience of radiology residents, especially in the early training phase. This model is of particular value for smaller to medium-sized academic institutions with limited financial and educational resources.
Gambling bank behaviour, incentive mechanism, and sanctions: A two-stage model
Authors: Strecker Isabel
Published: September 2023

This article analyses the optimal punishment structure set by a regulator in banking markets under asymmetric information. Relying on a theoretical model, we analyse whether a decreasing, constant, or increasing sanction scheme deters potentially repeated offences in banking. We find that an increasing punishment structure is efficient in reducing gambling bank behaviour. This holds if and only if the regulator’s detection probability is low or the amount gambled by the bank, if it would cheat, is high. With this paper, we provide justification for the current policy practice.
Impact of urbanization and income inequality on life expectancy of male and female in South Asian countries: a moderating role of health expenditures
Authors: Ahmad Nisar , Raid Moodhi , Alzyadat Jumah , Alhawal Hisham
Published: September 2023

Urbanization, income inequality and health expenditures are important factors of life expectancy. Urbanization and income inequalities are avoidable occurrences to tackle the health penalties. The objective of this study is to estimate the impact of urbanization and income inequality on the life expectancy male and female in six selected South Asian countries. To investigate the impact of urbanization and income inequality on life expectancy, eight econometric models are specified and estimated with recent panel data from 1997 to 2021. Based on the Hausman test, the random effect model is used for estimation. Life expectancy male and life expectancy female, respectively, are the dependent variables. Urbanization and income inequality are the independent variables, and health expenditure is the control variable. Further, the study finds the interaction effect of health expenditure with urbanization on life expectancy (male and female). Results explain that urbanization, income inequality and health expenditure have significant impacts on life expectancy in the case of both male and female. In both cases, life expectancy is negatively affected by urbanization and income inequality, whereas health expenditure has a positive impact on life expectancy. Health expenditures moderate the impact of urbanization on life expectancies of male and female with a small size effect. It explains that the negative impact of urbanization can be mitigated through health expenditures. The results of the study are robust. Based on the results of the study, policy-makers may suggest overcoming the problems of urbanization. It is a dire need to redistribute income in South Asian countries to achieve better health and improve life expectancy. More public health expenditures are required in these countries to provide more health facilities, especially in urban areas, to mitigate the impact of urbanization on life expectancy.
Profile of the poultry system and the socio-economic impact of native chickens as a potential development area in South Sulawesi, Indonesia
Authors: Asnawi Aslina , Ridwan Muh. , Nurlaelah Siti , Amrawaty Andi Amidah , Baba Syahdar , Kasim Kasmiyati
Published: September 2023

Context Native chicken farming has potential for development in several areas in Indonesia, because it is a very familiar practice and has specific community value. Both men and women have a role in raising native chickens. Aims To construct a profile of the poultry system and determine the potential socio-economic impacts for meeting community needs as a basis for the development of future native chicken enterprises. Methods The study was conducted in five areas in South Sulawesi, Indonesia, including Barru, Enrekang, Jeneponto, Maros, and Soppeng regencies. Interviews included 385 respondents (55.06% men and 44.94% women), most of whom were in the productive-age category (defined as 31–62 years of age) and were elementary school graduates. The number of family members was low, as was the number of chickens owned, being up to 25 chickens raised per year. Key results Native chicken farming was determined to have a moderate socio-economic impact on communities, as the number of chickens owned was relatively low. Native chickens are used for consumption, income generation and savings, and as complements in religious and traditional ceremonies. The potential target markets for native chickens are diverse, including individual end consumers, restaurants, local markets, and inter-regional markets. The amount of income from selling chickens varies depending on the quantity sold and the price. The price of chicken will rise under certain conditions, such as during religious and traditional events. Technical production constraints to market development include inadequate housing, lack of sanitation, non-optimal disease management, and low use of vaccinations. The primary market constraint is that the rearing locations can be far from the city centre, and the number of chickens that can be produced for sale is low. Conclusions Poultry management dynamics, such as feeding, housing, and sanitation, must be considered to expand native chicken production. It is essential to identify solutions for selling native chickens to significantly increase household income. Native chickens have a socio-economic impact, raising the family income, as complements in religious and traditional ceremonies, and affecting the social status of breeders. Implications Information regarding the potential and prospects of native chicken farming from a socio-economic perspective can encourage communities to maintain and develop livestock enterprises to support the provision of animal protein for consumption and traditional uses, and to increase household incomes.
Feasibility and economic costs of syphilis self-testing to expand test uptake among gay, bisexual and transgender men: results from a randomised controlled trial in Zimbabwe
Authors: Nhamo Definate , Mangenah Collin , Chapwanya Gwendoline , Mamvuto Takudzwa , Mahaka Imelda , Sri-Pathmanathan Clarisse , Ferrand Rashida A. , Kranzer Katharina , Terris-Prestholt Fern , Marks Michael , Tucker Joseph D.
Published: September 2023

Background Access to syphilis testing and treatment is frequently limited for men who have sex with men (MSM). A two-armed randomised controlled trial compared feasibility and costs of facility-based syphilis testing with self-testing among MSM in Zimbabwe. Methods This randomised controlled trial was conducted in Harare, with participants randomised 1:1. Syphilis self-testing was offered in community-based settings. The primary outcome was the relative proportion of individuals taking up testing. Total incremental economic provider and user costs, and cost per client tested, diagnosed and treated were assessed using ingredients-based costing in 2020 US$. Results A total of 100 men were enrolled. The two groups were similar in demographics. The mean age was 26 years. Overall, 58% (29/50) and 74% (37/50) of facility- and self-testing arm participants, respectively, completed syphilis testing. A total of 28% of facility arm participants had a reactive test, with 50% of them returning for confirmatory testing yielding 28% reactivity. In the self-testing arm, 67% returned for confirmatory testing, with a reactivity of 16%. Total provider costs were US$859 and US$736, and cost per test US$30 and US$15 for respective arms. Cost per reactive test was US$107 and US$123, and per client treated US$215 and US$184, respectively. The syphilis test kit was the largest cost component. Total user cost per client per visit was US$9. Conclusion Syphilis self-testing may increase test uptake among MSM in Zimbabwe. However, some barriers limit uptake including lack of self-testing and poor service access. Bringing syphilis testing services to communities, simplifying service delivery and increasing self-testing access through community-based organisations are useful strategies to promote health-seeking behaviours among MSM.
Recent progress in process, structure, properties, and performance in additive manufacturing
Authors: Mukherjee Tuhin
Published: September 2023

The similarities between additive manufacturing (AM) and fusion welding have made Science and Technology of Welding and Joining an appropriate venue to discuss the recent progress made in AM. This special issue highlights significant recent progress in AM towards inventing new processes, developing novel materials, improving microstructure, achieving unique mechanical properties, and reducing defects. Furthermore, it identifies the modern tools of the digital age such as mechanistic modelling, machine learning, and digital twin as powerful drivers of this progress. The articles in this special issue are also believed to identify research needs and opportunities for the AM community.
Experimental and statistical investigation into surface characteristics in micro milling of bottom pouring/gravity stir cast Al6061 alloy
Authors: Rawal Sunil , Kumar Mayank , Sidpara Ajay M , Paul Jinu
Published: September 2023

Micro milling offers the best way to create micro channels; however, the burr formation and surface roughness of the micro channel are difficult to control. Micro channel fabrication and their characterization of stir cast Al6061 are rarely investigated. In the present study, Al6061 alloy was processed by the bottom pouring stir casting method. The micro channels were fabricated on a base and stir cast Al6061 alloys using TiSIN-coated micro end mill tools. The influence of micromachining parameters such as spindle speed, feed rate, and depth of cut on burr formation, cutting force, burr size, and surface roughness was investigated. A comparison was made between the findings obtained from the micro milling of the base and stir cast Al6061 alloys. The surface morphology of fabricated micro channels was analysed and correlated with the roughness profile to understand the channel profile and burr formation. The top burr formation mechanism in stir cast Al6061 alloy was investigated in detail. Low feed rate, low depth of cut, and high spindle speed produced the micro channel with fewer burrs, low surface roughness, and low cutting forces. At the optimum parameter, stir cast Al6061 alloy showed an approximate 420%, 16%, and 300% increase in Fy, Fz, and Ra, respectively, as compared to the base Al6061 alloy. Adhesion wear, built-up edge, and microchipping were found to be the main tool wear mechanisms in micro machining of stir cast alloy. This study directs the choice of cutting parameters for the stir cast micro milling process.
Low-frequency broadband absorber with coherent coupling based on perforated panel and space-coiling channels
Authors: Wang Gongxian , Luo Gang , Xiang Lei , Yin Xuewen
Published: September 2023

Efficient broadband absorption of low-frequency sound via ultra-thin structure remains challenging due to the narrow-band property generated by the dispersive nature of resonance. In this study, we investigate the absorption mechanism of a component composed of a perforated panel and space-coiling channels through the coupling effect, acoustic impedance matching, and complex frequency analysis. In addition, the influence of geometrical parameters, resonance frequency intervals, and number of components in the coupled system on the band is investigated. Accordingly, the strategy for developing absorbers is to design individual components in the under-damped state by adjusting the geometrical parameters, then put together multiple components with different channel lengths in parallel. On the basis of this strategy, a low-frequency and broadband absorber is theoretically proposed and experimentally demonstrated, which can achieve broadband absorption from 250 Hz to 450 Hz. The design strategy has potential applications in low-frequency noise control engineering, such as plants, automotive and aerospace industries.
Transition metal doped WSi2N4 monolayer for water splitting electrocatalysts: a first-principles study
Authors: Huang Mengya , Jiang Yan , Luo Zijiang , Wang Jihong , Ding Zhao , Guo Xiang , Liu Xuefei , Wang Yi
Published: September 2023

High-performance water splitting electrocatalysts are urgently needed in the face of the environmental degradation and energy crisis. The first principles method was used in this study to systematically examine the electronic characteristics of transition metal (Sc, Ti, V, Cr, Mn, Fe, and Ru) doped WSi2N4 (TM@WSi2N4) and its potential as oxygen evolution reaction (OER) catalysts. Our study shows that the doping of TM atoms significantly improves the catalytic performance of TM@WSi2N4, especially Fe@WSi2N4 shows a low overpotential (η
OER = 470 mV). Interestingly, we found that integrated-crystal orbital Hamilton population and d-band center can be used as descriptors to explain the high catalytic activity of Fe@WSi2N4. Subsequently, Fe@WSi2N4 exhibits the best hydrogen evolution reaction (HER) activity with a universal overpotential of 47 mV on N1 sites. According to our research, Fe@WSi2N4 offers a promising substitute for precious metals as a catalyst for overall water splitting with low OER and HER overpotentials.
Strong ultrafast demagnetization due to the intraband transitions
Authors: Murakami Mitsuko , Zhang G P
Published: September 2023

Demagnetization in ferromagnetic transition metals driven by a femtosecond laser pulse is a fundamental problem in solid state physics, and its understanding is essential to the development of spintronic devices. Ab initio calculation of time-dependent magnetic moment in the velocity gauge so far has not been successful in reproducing the large amount of demagnetization observed in experiments. In this work, we propose a method to incorporate intraband transitions within the velocity gauge through a convective derivative in the crystal momentum space. Our results for transition-element bulk crystals (bcc Fe, hcp Co and fcc Ni) based on the time-dependent quantum Liouville equation show a dramatic enhancement in the amount of demagnetization after the inclusion of an intraband term, in agreement with experiments. We also find that the effect of intraband transitions on each ferromagnetic material is distinctly different because of their band structure and spin property differences. Our finding has a far-reaching impact on understanding of ultrafast demagnetization.
Microstructural mechanisms of hysteresis and transformation width in NiTi alloy from molecular dynamics simulations
Authors: Plummer Gabriel , Mendelev Mikhail I , Benafan Othmane , Lawson John W
Published: September 2023

Martensitic transformations in shape memory alloys are often accompanied by thermal hysteresis, and engineering this property is of prime scientific interest. The martensitic transformation can be characterized as thermoelastic, where the extent of the transformation is determined by a balance between thermodynamic driving force and stored elastic energy. Here we used molecular dynamics simulations of the NiTi alloy to explore hysteresis-inducing mechanisms and thermoelastic behavior by progressively increasing microstructural constraints from single crystals to bi-crystals to polycrystals. In defect-free single crystals, the austenite-martensite interface moves unimpeded with a high velocity. In bi-crystals, grain boundaries act as significant obstacles to the transformation and produce hysteresis by requiring additional nucleation events. In polycrystals, the transformation is further limited by the thermoelastic balance. The stored elastic energy can be converted to mechanisms of non-elastic strain accommodation, which also produce hysteresis. We further demonstrated that the thermoelastic behavior can be controlled by adjusting microstructural constraints.
A small sample diagnosis method driven by simulation and test data: applied to axle box bearings of high-speed train
Authors: Xie Jingsong , Tian Longzhen , Lin Mingqi , Yang Buyao , Yang Jinsong , Wang Tiantian
Published: September 2023

Fault diagnosis of axle box bearings is an important technology to improve the service safety and economy of high-speed trains. However, it is difficult to obtain sufficient fault samples in actual train operation, which limits the application of deep learning methods in the field of high-speed train fault diagnosis. Therefore, in this paper, a simulation and test data fusion-driven fault diagnosis method for axle box bearings with few samples is proposed. In this method, a bearing dynamics model is constructed to obtain simulation data for fault bearings, and the accuracy of the constructed dynamics model is verified by experimental data. Data fusion methods are proposed which use massive simulated fault samples and only normal test samples to construct new samples for the pre-training of deep learning diagnostic models. The parameter transfer strategy is used to fine-tune the diagnostic model with a small amount of test fault samples. A real train experiment is carried out for validating the proposed methods which use the real fault bearings that fail during operation. The results show that the proposed method via the fusion of simulation and test data has higher generalization ability and diagnostic accuracy in small sample situations.
Wavelength-tunable broadband lasers based on nanomaterials
Authors: Zhang Chenxi , Zhang Congyu , Li Yiwei , Shi Yaran , Chao Jiale , Zhao Yifan , Yang He , Fu Bo
Published: September 2023

Nanomaterials are widely used in the fields of sensors, optoelectronics, biophotonics and ultrafast photonics due to their excellent mechanical, thermal, optical, electrical and magnetic properties. Particularly, owing to their nonlinear optical properties, fast response time and broadband operation, nanomaterials are ideal saturable absorption materials in ultrafast photonics, which contribute to the improvement of laser performance. Therefore, nanomaterials are of great importance to applications in wavelength-tunable broadband pulsed lasers. Herein, we review the integration and applications of nanomaterials in wavelength-tunable broadband ultrafast photonics. Firstly, the two integration methods, which are direct coupling and evanescent field coupling, and their characteristics are introduced. Secondly, the applications of nanomaterials in wavelength-tunable broadband lasers are summarized. Finally, the development of nanomaterials and broadband tunable lasers is reviewed and discussed.
Design of Nb5+-doped high-nickel layered ternary cathode material and its structure stability
Authors: Zhao Tingting , Liu Pei , Tang Fuli , Xiao Minzhi , Song Liubin , Kuang Yinjie , Long Tianyuan , Xiao Zhongliang
Published: September 2023

LiNi0.8Co0.1Mn0.1O2 (NCM811) is one of the most promising cathode materials for high-energy lithium-ion batteries, but there are still problems such as rapid capacity decay during charge and discharge and poor cycle performance. Elemental doping can significantly improve the electrochemical performance of high nickel ternary cathode materials. In this work, Nb5+-doped NCM811 cathode material was successfully synthesized. The results show that Nb5+ doping helps to increase the interlayer spacing of the lithium layer, electron transport, and structural stability, thereby significantly improving the conductivity of Li+. At a high voltage of 4.6 V, the initial discharge specific capacity of 1% Nb5+-doped NCM811 cathode material at 0.1 C is 222.3 mAh·g−1, and the capacity retention rate after 100 cycles at 1 C is 92.03%, which is far more than the capacity retention rate of NCM811 under the same conditions (74.30%). First-principles calculations prove that 1% Nb5+-doped NCM811 cathode material shows the highest electronic conductivity and Nb5+ doping will not change the lattice structure, demonstrating the effectiveness of the proposed strategy.
Density functional theory studies of Ti3C2T
x
MXene nanosheets decorated with Au for sensing SF6/N2 nitrogen-containing decomposition gases
Authors: Zeng Fuping , Qiu Hao , Feng Xiaoxuan , Guo Xinnuo , Zhu Kexin , Yao Qiang , Tang Ju
Published: September 2023

SF6/N2 mixture is an alternative gas of SF6, which is already used in electrical equipment. When a malfunction occurs , SF6/N2 will decompose and further react with trace water and oxygen to produce nitrogen-containing gases such as NO, NO2, N2O and NF3. It is necessary to monitor these gases to ensure the safe operation of the equipment. This paper is based on density functional theory (DFT), the nanomaterial Ti3C2T
x
doped with Au atom was selected as sensing material. The result shows that Au/Ti3C2T
x
has larger adsorption energy when NO and NO2 adsorbed on the surface, the stable structures were conformed more easily with NO and NO2 compared with N2O and NF3. The density of states analysis and the frontier molecule orbital analysis reveal more change of the system before and after NO and NO2 adsorption, suggesting the material showed good sensitivity performance to NO and NO2. Thus, Au/Ti3C2T
x
is considered to have the potential for sensing NO and NO2.
Thickness effect of 2D PdSe2 film on performance of PdSe2/Si heterostructure photodetectors
Authors: Hu Yiping , Zhu Qinghai , Sun Jiabao , Sun Yijun , Hanagata Nobutaka , Xu Mingsheng
Published: September 2023

Two-dimensional (2D) PdSe2 film has the characteristics of adjustable bandgap, high carrier mobility, and high stability. Photodetector (PD) based on 2D PdSe2 exhibits wide spectral self-driving features, demonstrating enormous potential in the field of optical detection. Here, we design and fabricate PdSe2/Si heterojunction PDs with various thicknesses of the PdSe2 films from 10 to 35 nm. Due to the enhancement of light absorption capacity and built-in electric field of heterojunction, the photodetector with thicker PdSe2 film can generate more photo-generated carriers and effectively separate them to form a large photocurrent, thus showing more excellent photodetection performance. The responsivity and specific detectivity of the PdSe2/Si PDs with 10 nm, 20 nm, and 35 nm PdSe2 films are 2.12 A W−1 and 6.72 × 109 Jones, 6.17 A W−1 and 1.95 × 1010 Jones, and 8.02 A W−1 and 2.54 × 1010 Jones, respectively (808 nm illumination). The PD with 35 nm PdSe2 film exhibits better performance than the other two PDs, with the rise/fall times of 15.8 μs/138.9 μs at f = 1 kHz and the cut-off frequency of 8.6 kHz. Furthermore, we demonstrate that the properties of PdSe2/Si PD array have excellent uniformity and stability at room temperature and shows potential for image sensing in the UV–vis-NIR wavelength range.
Studies on laser surface processing of titanium based alloy (Ti6Al4V) with titanium, carbon and a mixture of titanium and carbon
Authors: Gayen Tarun Kumar , Pityana Sisa , Akinlabi Esther , Majumdar Jyotsna Dutta
Published: September 2023

The present study concerns the development of titanium carbide (TiC) dispersed titanium matrix composite by laser surface processing of titanium with titanium and carbon (in the weight ratio of 90:10 and 50:50). Laser surface processing has been carried out using a 4 kW continuous wave (CW) Nd:YAG laser with a beam diameter of 2 mm, at varied applied power ranging from 600–900 W and a scan speed of 0.6 m s−1 by pre-deposition of precursor powder and its subsequent melting using laser in argon shroud. Followed by laser surface processing, a detailed characterization of the processed zone has been carried out in terms of microstructure, phase, and composition. Properties of the surface processed zone were evaluated in terms of corrosion resistance in Hank’s solution. Finally, the optimum process parameters for laser surface processing has been established through a detailed structure–property-process parameters correlation. The microstructure of the surface processed zone consists of presence of titanium carbides dispersed in α matrix, the mass fraction of carbide phase was found to vary with weight percentage of graphite present in the precursor powder. The corrosion resistance property of the surface was found to be improved in terms of decrease in corrosion rate (range of 0.001 mm to 0.03 mm per year) as compared to as-received Ti-6Al-4V (0.2 mm per year). Laser surface processing with 100% graphite shows a maximum improvement in corrosion and bio-activity.
A neural network regression model for estimating the lifespan of a Fibre Bundle
Authors: V Gokul , Singh Navin
Published: September 2023

Fibre Bundle Models (FBMs) use generalized distributions like the Weibull distribution to study the failure mechanics of disordered material under different load-sharing schemes. Here we attempt to use a simple neural network regression model to estimate the lifespan of Fibre Bundles for axial loading under the Global Load Sharing (GLS) scheme. We find that using neural networks can give a reliable estimate (within ∼2%) of the lifespan for different initial conditions. We also develop a semi-analytical expression for the lifespan of a bundle of fibres. The aim is to establish an empirical relationship using a neural network regression (NNR) method that helps us estimate the ultimate tensile strength. The expressions and methods developed here can be a precursor to future investigation under those cited in the following section(s).
SPR-Based refractive index sensor using BaTiO3 and WS2 with Al-Ni bimetal for glucose sensing
Authors: Uwais Mohd , Bijalwan Ashish , Rastogi Vipul
Published: September 2023

In this work, we propose a high-performance surface plasmon resonance (SPR)-based refractive index biosensor to determine the glucose concentration in the urine samples. To achieve the most efficient design for the sensor, four possible designs have been investigated. The proposed design of the sensor uses the Kretschmann configuration, which consists of a BK7 glass prism with Aluminum (Al) and Nickel (Ni) metallic layers separated by a dielectric layer of barium titanate (

BaTiO

3

), and a 2D material tungsten disulfide (

WS

2

) layer placed above the Ni layer. The dielectric layer of

BaTiO

3

is used to enhance the shift in the resonance angle and

WS

2

to increase the absorption of the biomolecules, which results in an increase in the sensitivity of the sensor. The performance of the sensor has been numerically investigated using the transfer matrix method at

633

nm

wavelength. Minimum reflectance at resonance is studied to show the coupling strength of the incident light with the surface plasmons. The thicknesses of the Al and Ni metallic layers have been optimized for maximum sensitivity and minimum reflectance at the resonance. The performance of the proposed sensor has been investigated to obtain sensitivity for different glucose concentrations in the urine samples. The sensor has a sensitivity of

330.5
°
/
RIU

for glucose concentration in the range

0
−
10

g\dl
.

The corresponding glucose concentration sensitivity is 0.4

°
/
(
g
/
dl
)
.

The proposed study would be helpful in designing the refractive index-based biosensor for medical diagnostics applications.
A Novel Low-frequency Radio Astronomical Observation Array (1 ∼ 90 MHz) and its First Light
Authors: Yang Wen-Jun , Wang Zhen , Wang Ming-Yuan , Yan Fa-Bao , Lu Guang , Gao Guan-Nan , Guo Shao-Jie , Shen Yu-Mei , Xu Bing-Qiang , Bai Yu , Chen Yong , Ping Jin-Song
Published: September 2023

The extremely low frequency (f < 40 MHz) is a very important frequency band for modern radio astronomy observations. It is also a key frequency band for solar radio bursts, planetary radio bursts, fast radio bursts detected in the lunar space electromagnetic environment, and the Earth’s middle and upper atmosphere with low dispersion values. In this frequency band, the solar stellar activity, the early state of the universe, and the radiation characteristics of the planetary magnetosphere and plasma layer can be explored. Since there are few observations with effective spatial resolution in the extremely low frequency, it is highly possible to discover unknown astronomical phenomena on such a band in the future. In conjunction with low frequency radio observation on the far side of the Moon, we initially set up a novel low-frequency radio array in the Qitai station of Xinjiang Astronomical Observatory deep in Tianshan Mountains, Xinjiang, China on 2021 August 23. The array covers an operating frequency range of 1 ∼ 90 MHz with a sensitivity of −78 dBm/125kHz, a dynamic range of 72 dB, and a typical gain value of 6 dBi, which can realize unattended all-weather observations. The two antennas due south of the Qitai Low-Frequency Radio Array were put into trial observations on 2021 May 28, and the very quiet electromagnetic environment of the station has been confirmed. So far, many solar radio bursts and other foreign signals have been detected. The results show that this novel low frequency radio array has the advantages of good performance, strong direction, and high antenna efficiency. It can play a unique role in Solar Cycle 25, and has a potential value in prospective collaborative observation between the Earth and space for extremely low frequency radio astronomy.
Prediction of Short Stellar Activity Cycles using Derived and Established Empirical Relations between Activity and Rotation Periods
Authors: Althukair A. K. , Tsiklauri D.
Published: September 2023

In our previous work, we investigated the occurrence rate of super-flares on various types of stars and their statistical properties, with a particular focus on G-type dwarfs, using entire Kepler data. The said study also considered how the statistics change with stellar rotation period, which in turn, had to be determined. Using such new data, as a by-product, we found 138 Kepler IDs of F- and G-type main sequence stars with rotation periods less than a day (P
rot < 1 day). On one hand, previous studies have revealed short activity cycles in F-type and G-type stars and the question investigated was whether or not short-term activity cycles are a common phenomenon in these stars. On the other hand, extensive studies exist which establish an empirical connection between a star’s activity cycle and rotation periods. In this study, we compile all available Kepler data with P
rot < 1 day, and rely on an established empirical relation between P
cyc and P
rot with the aim to provide predictions for very short 5.09 ≤ P
cyc ≤ 38.46 day cases in a tabular form. We propose an observation to measure P
cyc using a monitoring program of stellar activity (e.g., activity-related chromospheric emission S-index) or a similar means for the Kepler IDs found in this study in order put the derived empirical relations between P
cyc and P
rot derived here to the test. We also propose an alternative method for measuring very short P
cyc, using flare-detection algorithms applied to future space mission data.
Hippocampal network axons respond to patterned theta burst stimulation with lower activity of initially higher spike train similarity from EC to DG and later similarity of axons from CA1 to EC
Authors: Chen Ruiyi , Vakilna Yash Shashank , Lassers Samuel Brandon , Tang William C , Brewer Gregory
Published: September 2023

Objective. Decoding memory functions for each hippocampal subregion involves extensive understanding of how each hippocampal subnetwork processes input stimuli. Theta burst stimulation (TBS) recapitulates natural brain stimuli which potentiates synapses in hippocampal circuits. TBS is typically applied to a bundle of axons to measure the immediate response in a downstream subregion like the cornu ammonis 1 (CA1). Yet little is known about network processing in response to stimulation, especially because individual axonal transmission between subregions is not accessible. Approach. To address these limitations, we reverse engineered the hippocampal network on a micro-electrode array partitioned by a MEMS four-chambered device with interconnecting microfluidic tunnels. The micro tunnels allowed monitoring single axon transmission which is inaccessible in slices or in vivo. The four chambers were plated separately with entorhinal cortex (EC), dentate gyrus (DG), CA1, and CA3 neurons. The patterned TBS was delivered to the EC hippocampal gateway. Evoked spike pattern similarity in each subregions was quantified with Jaccard distance metrics of spike timing. Main results. We found that the network subregion produced unique axonal responses to different stimulation patterns. Single site and multisite stimulations caused distinct information routing of axonal spikes in the network. The most spatially similar output at axons from CA3 to CA1 reflected the auto association within CA3 recurrent networks. Moreover, the spike pattern similarities shifted from high levels for axons to and from DG at 0.2 s repeat stimuli to greater similarity in axons to and from CA1 for repetitions at 10 s intervals. This time-dependent response suggested that CA3 encoded temporal information and axons transmitted the information to CA1. Significance. Our design and interrogation approach provide first insights into differences in information transmission between the four subregions of the structured hippocampal network and the dynamic pattern variations in response to stimulation at the subregional level to achieve probabilistic pattern separation and novelty detection.
Suppression of cortical electrostimulation artifacts using pre-whitening and null projection
Authors: Lim Jeffrey , Wang Po T , Bashford Luke , Kellis Spencer , Shaw Susan J , Gong Hui , Armacost Michelle , Heydari Payam , Do An H , Andersen Richard A , Liu Charles Y , Nenadic Zoran
Published: September 2023

Objective. Invasive brain–computer interfaces (BCIs) have shown promise in restoring motor function to those paralyzed by neurological injuries. These systems also have the ability to restore sensation via cortical electrostimulation. Cortical stimulation produces strong artifacts that can obscure neural signals or saturate recording amplifiers. While front-end hardware techniques can alleviate this problem, residual artifacts generally persist and must be suppressed by back-end methods. Approach. We have developed a technique based on pre-whitening and null projection (PWNP) and tested its ability to suppress stimulation artifacts in electroencephalogram (EEG), electrocorticogram (ECoG) and microelectrode array (MEA) signals from five human subjects. Main results. In EEG signals contaminated by narrow-band stimulation artifacts, the PWNP method achieved average artifact suppression between 32 and 34 dB, as measured by an increase in signal-to-interference ratio. In ECoG and MEA signals contaminated by broadband stimulation artifacts, our method suppressed artifacts by 78%–80% and 85%, respectively, as measured by a reduction in interference index. When compared to independent component analysis, which is considered the state-of-the-art technique for artifact suppression, our method achieved superior results, while being significantly easier to implement. Significance. PWNP can potentially act as an efficient method of artifact suppression to enable simultaneous stimulation and recording in bi-directional BCIs to biomimetically restore motor function.
Synthesis, characterization, and fluorescence properties of SrAl2B2O7:Eu2+ and SrAl2B2O7:Eu2+, Li+
Authors: Li Sheng , Jiao Zhiwei , Guo Yanxing , Liu Shuchang , Wu Yuhao , Qin Guangcan
Published: September 2023

The blue-emitting phosphor SrAl2B2O7:Eu2+ has the potential to be used in full-spectrum LED devices. However, the reducing atmosphere is extremely demanding in the complex preparation process of SrAl2B2O7:Eu2+. Thereby, the synthesis of SrAl2B2O7:Eu2+ with an economic approach is important. In this work, a new synthesis route was realized; SrAl2O4:Eu2+ and H3BO3 were used as solid precursors to synthesize SrAl2B2O7:Eu2+ by solid-state reaction method, and only carbon powder is needed as a source of reducing atmosphere. The effects of different synthesis routes on the crystal structure, morphology, and luminescence properties of SrAl2O4:Eu2+ were studied, as well as the effects of Li+ doping on luminescence properties were investigated. The results show that under the new synthesis route, SrAl2B2O7:Eu2+ has good luminescence properties, and doping Li+ will improve the luminescence intensity.
Study on mechanical properties of multi-fiber reinforced fly ash concrete
Authors: Zhang Wei , Chen Chengqin , Wu Hongjuan , Mao Yuncheng
Published: September 2023

Aiming at the problems of low strength and easy cracking of concrete with large dosages of fly ash, SSF, ARF, and PPF were mixed into concrete respectively according to the same volume ratio. Various indexes were tested and the change rule was analyzed. Besides, the fiber spacing theory was adopted to explore the anti-cracking mechanism of fiber on concrete. The results indicate that the compressive strength and flexural strength of concrete were improved by three kinds of fiber in different dosage; the RFC of 7d was between 14% and 18%, and that of 28d was between 13% and 20%; SSF in concrete would produce strong bonding force and mechanical bite force. ARF has a small impact on the compressive strength of concrete, but a significant impact on the flexural strength of concrete. PPF can be more evenly dispersed in concrete to disperse and release a certain amount of stress and play a reinforcing role. Combined with SEM Microscopic Morphology Analysis of Concrete, a concrete mix ratio of three fibers 1:1:1 is recommended.
Experimental study on defects of needled quartz fiber reinforced phenolic aerogel composites by cryogenic milling
Authors: Zhang Yu , Han Lingsheng , Yu Qingbo , Yang Yuebing , Liu Kuo , Liu Haibo , Wang Yongqing
Published: September 2023

Needled quartz fiber reinforced phenolic aerogel composite (NQF/PA) is a kind of lightweight thermal protection material commonly used in the aerospace field. With the continuous development of aerospace science and technology, the design of various spacecraft is becoming more and more complex. Due to the limitation of the preparation process, thermal protection components are difficult to be directly prepared and formed. It is often necessary to carry out secondary processing in order to bond and assemble into a large-size combined thermal protection system. Because NQF/PA composites have the characteristics of high fiber toughness and easy cracking of the matrix, it is easy to cause processing defects such as burrs, tearing and edge collapse in dry machining. Cryogenic machining can improve the machinability of fiber-reinforced composites. However, there is still a lack of research on the cryogenic machining of NQF/PA composites. In order to analyze the feasibility of cryogenic machining technology for low-damage processing of NQF/PA composites, this paper carried out a comparative experimental study on dry machining and cryogenic machining of NQF/PA composites and analyzed the influence of spindle speed, feed rate and radial cutting depth on surface defects and cutting force. The research showed that under the same processing parameters, compared with dry machining, cryogenic machining can effectively reduce the cutting force and suppress processing defects.
The Effect of Trivalent Ions on Luminescent Properties of SrAl2O4:Eu2+, Dy3+ Phosphors
Authors: Guo Yanxing , Jiao Zhiwei , Cao Leigang , Li Sheng
Published: September 2023

Sr0.96Al2O4:Eu0.02, Dy0.02 green phosphors doped with La3+, Bi3+ and extra Dy3+ were successfully prepared by the solid-phase method. The crystal structure and luminescence properties of phosphors were characterized. The results showed that the doping of La3+ and Bi3+ and the continued increase of Dy3+ concentration in the SrAl2O4 lattice did not produce significant lattice distortion in the SrAl2O4 lattice, and the small amount of doping still maintained the presence of SrAl2O4. The photoluminescence intensity of both La3+ and Bi3+ doped samples showed an increasing and then decreasing trend within the doping amount, while the photoluminescence performance of Dy3+ doped samples did not show a decrease when increasing the same concentration of doping amount. The decay curves indicated that both La3+ and Bi3+ could decrease the afterglow time of SrAl2O4:Eu2+, Dy3+ phosphor, but increasing the concentration of Dy3+ effectively extends the afterglow time of SrAl2O4:Eu2+, Dy3+ phosphor.
Study on preparation and properties of PVDF/CB composite films
Authors: Zhen Wanqing , Nie Fu , Yang Hongcheng , Fei Hailin , Wang Peng
Published: September 2023

Carbon black was often used as a UV stabilizer, due to its ability to absorb high-energy ultraviolet radiation. In this study, carbon black was added to PVDF resin, and PVDF film with carbon black (PVDF/CB composite film) was fabricated using a precision co-extrusion casting mechanism. The properties of the films were characterized by differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), field emission scanning electron microscope (FESEM), water contact angle (WCA), and universal material testing machine. Furthermore, the DSC results suggested that the melting temperature (Tm) of PVDF/CB composite film was 168.7°C. The TGA results showed that the initial decomposition temperature (Td) of PVDF/CB composite film was 358.9°C. The FESEM observation showed that the surface of the PVDF/CB composite film was smooth without obvious defects. The WCA results indicated that PVDF/CB composite film had good hydrophobicity. In addition, the UV transmittance results presented that PVDF/CB composite film had higher UV aging resistance than that PVDF film.
Topology Optimization of Dual-Material Structures with Porous Materials
Authors: Zhou Yifan
Published: September 2023

To improve the buckling resistance of the structure and the effective utilization of materials, a topology optimization algorithm using dual materials is designed in this paper. Among them, the two materials are solid and porous, respectively. The single-material structure topology optimization algorithm in two-dimensional structures has been relatively perfect. However, the two-dimensional algorithm is limited to the topology optimization of a single material, and it cannot improve the buckling resistance of the actual compression structure. At the same time, the optimization algorithm for the three-dimensional structure still needs to be improved. The dual-material topology optimization algorithm using porous materials constructed in this paper assigns porous materials with good compressive capacity to the compression parts and solid materials with good tensile properties to the tension parts. Therefore, the structure of the compression part of the structure is strengthened, and the unnecessary structure of the tension part is simplified. In conclusion, the algorithm in this paper greatly improves the buckling resistance of the structure and maximizes the utilization of each design unit.
Synthesis of ZIF-L-derived Leaf-like Carbon Support Ultrafine Pt Nanoparticles for Oxygen Reduction Reaction
Authors: Huang Qirui
Published: September 2023

We prepared a two-dimensional ZIF-L-derived high-performance ORR catalyst using a mesoporous silica coating strategy. By one-step pyrolysis of mSiO2@L composite, the Pt precursors adsorbed inside ZIF-L are reduced to ultra-small Pt nanoparticles, and the SiO2 template inhibits agglomeration and collapse of ZIF-L during pyrolysis. After the template is removed, the obtained Pt/SLC exhibits outstanding activity for ORR. The half-wave potential of Pt/SLC is 0.910 V vs. RHE, which far exceeds commercial Pt/C catalyst (0.895 V vs. RHE).
Impact Resistance and Energy Absorption Characteristics of the Bionic Turtle Shell Structure
Authors: Song Yuting , Shi Weichen
Published: September 2023

The microstructure of the shell is a kind of “sandwich” structure with a denser outer layer and a less dense inner layer, density, which can be identified as a functional gradient material in engineering. It has excellent performance, such as earthquake resistance and shock resistance. In order to study the reliability of this kind of material, a kind of shell structure is designed in this paper. In the range of elastic deformation constraints of the material, simulate and calculate bionic structure the bionic structure. Firstly, a three-point bending analysis is carried out to investigate the mechanical properties of the bionic structure under a bending load. Secondly, through the Finite Element Analysis, the mechanical properties of the shell structure and the general structure under the same load are analyzed and compared. The simulation results show that in the three-point bending analysis, the maximum equivalent stress of the simulated shell structure under impact load is reduced by 1.4 times compared with the general structure. The energy absorption analysis showed a 1.6-fold increase.
Study on Crack Propagation in Proton Exchange Membranes with Doped Microcapsules
Authors: Yan Boru , Du Xin
Published: September 2023

Crack defects produced during the operation of proton exchange membrane fuel cells (PEMFCs) have a significant impact on their service life. One common approach to extend their working time is to embed self-healing microcapsules in the membrane to repair the defects. In this study, we use the extended finite element method (XFEM) to investigate the capture and control of cracks by doped microcapsules and numerically simulate the crack propagation patterns. The results show that a two-layer microcapsule distribution along the membrane cross-section can achieve complete control of cracks. In addition, the two-material microcapsules with layered, staggered arrangement exhibit the maximum distance between cracks they can attract, while minimizing their impact on the mechanical properties of the membrane. Based on these findings, we determine the theoretical doping amount of microcapsules per unit volume, which has important implications for future experimental design and engineering applications.