bluuebunny/crossref_metadata_2025 huggingface dataset:
n-type kesterite thermoelectric (Cu1−xAgx)2ZnSnS4 single crystals exceeding dimensionless figure of merit value of 1.0
Authors: Nagaoka Akira , Miura Shoma , Nakashima Koki , Hirai Yuichi , Higashi Tomohiro , Yoshino Kenji , Nishioka Kensuke
Published: August 2024

The lack of attractive n-type thermoelectric materials greatly restricts their applications because most high-performance materials are p-type conductors, such as the kesterite compound Cu2ZnSnS4. This study reports high-quality n-type kesterite (Cu1−xAgx)2ZnSnS4 (CAZTS) single crystals that exhibit a record high dimensionless figure of merit value of 1.1 at approximately 800 K, primarily owing to Ag alloying, cation compositional optimization, and intrinsic low thermal conductivity. An n-type CAZTS-based single-leg device was fabricated using a Mo-barrier layer. The device exhibited a thermoelectric conversion efficiency of 3.4% at a temperature gradient of 473 K. This study provides insights into developing thermoelectric modules using environmentally friendly kesterite materials.
Aluminum nanosized beams as probes of superfluid 4He
Authors: Noble M. T. , Guthrie A. , Jennings A. , Kafanov S. , Poole M. , Sarsby M. , Wilcox T. , Tsepelin V.
Published: August 2024

Sub-micrometer size devices are strong candidates for future use as probes of quantum fluids. They can be reproducibly manufactured with resonant frequencies in the range of kilohertz to gigahertz and have low power consumption and dissipation. Here, we present doubly clamped aluminum nanobeams of lengths from 15 μm up to 100 μm operated in vacuum and the hydrodynamic regime of liquid 4He. We observe that in vacuum devices are described well using a simple harmonic motion with a constant Duffing coefficient, and in helium, we quantitatively model their behavior with the conventional hydrodynamic model.
Laser-aided processing and functionalization of 2D materials
Authors: Li Runxuan , Blankenship Brian W. , Wu Junqiao , Rho Yoonsoo , Li Jingang , Grigoropoulos Costas P.
Published: August 2024

Atomically thin two-dimensional (2D) materials exhibit extraordinary optical, electrical, and mechanical properties. Many functional nanostructures and devices of exceptional performance based on 2D materials have been demonstrated. However, the processing of 2D materials remains challenging due to inadequacies that are mainly driven by high fabrication cost, complex steps, and inefficient impurity control. On the other hand, laser-aided processing techniques offer versatility, nanoscale precision, and high throughput. Numerous efforts have showcased the implementation of laser processing and functionalization of 2D materials to control their physical properties and optimize device functionality. In this Perspective, we summarize research progress on laser-enabled thinning, patterning, doping, and functionalization of 2D materials. Continuing advances in optical processing techniques are anticipated to further accelerate the deployment of 2D materials and devices in many fields, including photonics, optoelectronics, and sensor applications.
Binding energies of CD4 and fragment species to Pt(111): Implications for measurements of anion electron stimulated desorption
Authors: Omar Norhan , Cloutier Pierre , Ramseyer Christophe , Bass Andrew , Sanche Léon , Fromm Michel
Published: August 2024

We consider the electron stimulated desorption, via dissociative electron attachment, of anionic species from thin condensed CD4 films deposited on a Pt substrate and compare experimentally observed desorption yields with density functional theory calculations of the binding energies of various anionic and neutral moieties to Pt(111). Certain species (which can be considered chemisorbed) exhibit very high binding energies and large charge transfer with the substrate. Other “physisorbed” species have much lower binding energies. Species that chemisorb have lower desorption yields than those that physisorb, especially at 1–2 monolayer coverage of the Pt substrate. The binding energy of D− to Pt is the weakest, and experimentally, the desorption yield is the highest regardless of the thickness of CD4. The calculations show that the formation and desorption of anionic species at a distance of 16 Å from the substrate, which is equivalent to the thickness of CD4 films of four monolayers, are not influenced by the short-range interactions between the substrate and the molecule and DEA products.
IL-13 and IL-17A activate β1 integrin through an NF-kB/Rho kinase/PIP5K1γ pathway to enhance force transmission in airway smooth muscle
Authors: Ngo Uyen , Shi Ying , Woodruff Prescott , Shokat Kevan , DeGrado William , Jo Hyunil , Sheppard Dean , Sundaram Aparna B.
Published: August 2024

Integrin activation resulting in enhanced adhesion to the extracellular matrix plays a key role in fundamental cellular processes. Although integrin activation has been extensively studied in circulating cells such as leukocytes and platelets, much less is known about the regulation and functional impact of integrin activation in adherent cells such as smooth muscle. Here, we show that two different asthmagenic cytokines, IL-13 and IL-17A, activate type I and IL-17 cytokine receptor families, respectively, to enhance adhesion of airway smooth muscle. These cytokines also induce activation of β1 integrins detected by the conformation-specific antibody HUTS-4. Moreover, HUTS-4 binding is increased in the smooth muscle of patients with asthma compared to nonsmokers without lung disease, suggesting a disease-relevant role for integrin activation in smooth muscle. Indeed, integrin activation induced by the β1-activating antibody TS2/16, the divalent cation manganese, or the synthetic peptide β1-CHAMP that forces an extended-open integrin conformation dramatically enhances force transmission in smooth muscle cells and airway rings even in the absence of cytokines. We demonstrate that cytokine-induced activation of β1 integrins is regulated by a common pathway of NF-κB-mediated induction of RhoA and its effector Rho kinase, which in turn stimulates PIP5K1γ-mediated synthesis of PIP
2
at focal adhesions, resulting in β1 integrin activation. Taken together, these data identify a pathway by which type I and IL-17 cytokine receptor family stimulation induces functionally relevant β1 integrin activation in adherent smooth muscle and help to explain the exaggerated force transmission that characterizes chronic airway diseases such as asthma.
Entrainment echoes in the cerebellum
Authors: Zoefel Benedikt , Abbasi Omid , Gross Joachim , Kotz Sonja A.
Published: August 2024

Evidence accumulates that the cerebellum’s role in the brain is not restricted to motor functions. Rather, cerebellar activity seems to be crucial for a variety of tasks that rely on precise event timing and prediction. Due to its complex structure and importance in communication, human speech requires a particularly precise and predictive coordination of neural processes to be successfully comprehended. Recent studies proposed that the cerebellum is indeed a major contributor to speech processing, but how this contribution is achieved mechanistically remains poorly understood. The current study aimed to reveal a mechanism underlying cortico-cerebellar coordination and demonstrate its speech-specificity. In a reanalysis of magnetoencephalography data, we found that activity in the cerebellum aligned to rhythmic sequences of noise-vocoded speech, irrespective of its intelligibility. We then tested whether these “entrained” responses persist, and how they interact with other brain regions, when a rhythmic stimulus stopped and temporal predictions had to be updated. We found that only intelligible speech produced sustained rhythmic responses in the cerebellum. During this “entrainment echo,” but not during rhythmic speech itself, cerebellar activity was coupled with that in the left inferior frontal gyrus, and specifically at rates corresponding to the preceding stimulus rhythm. This finding represents evidence for specific cerebellum-driven temporal predictions in speech processing and their relay to cortical regions.
Establishing the Basis for Rabies Control in Liberia
Authors: Voupawoe Garmie , Varkpeh Roland , Mauti Stephanie
Published: August 2024

In 2017, the Swiss Tropical and Public Health Institute established a partnership with the Liberian Ministry of Agriculture on a rabies project entitled “Multicentre and multinational assessment of the burden of rabies and vaccination impact in West and Central Africa.” In Liberia, the project aimed to establish animal rabies diagnostics and foster collaboration between all stakeholders involved in rabies control. This case study highlights the opportunities and challenges of collaborating with sectors to control dog rabies. Before our intervention, sharing of information between sectors was difficult, and rabies was not confirmed in the animal population. For instance, data on animal bite cases were well-documented in the public health sector, but the numbers did not align with the data in the animal health sector. Through the project, we implemented the first animal rabies diagnostics in post-war Liberia at the Central Veterinary Laboratory. Subsequently, we utilized the One Health Platform of Liberia to improve direct communication between the public health and veterinary authorities, healthcare providers, and other rabies stakeholders. Despite numerous challenges, such as limited research and government investment in controlling the disease, this approach improved cross-information sharing and led to diagnosing the first rabies strain in post-war Liberia, thereby identifying the country as rabies-endemic. From 2019 to 2021, only 11,820 domestic animals were vaccinated, compared to an estimated nationwide population of approximately 600,000 dogs. Additionally, we strengthened the animal surveillance system at the Ministry of Agriculture, and conducted a Knowledge, Attitudes, and Practices study (subnational dog census in two highly affected counties) and a nationwide collection of suspected rabies samples for genome-based phylogenetic analysis of the rabies virus (Africa 2 lineage subgroup H) circulating in domestic dogs in Liberia. Our findings were summarized in a policy brief for governmental authorities aimed at eradicating dog rabies in Liberia.

Information

© The Authors 2024
Experimental investigation of electrostatic spinning of polylactic acid porous nanofibers
Authors: Wang Tao , Shang Xue , Wang Hu , Wang Jilai , Zhang Chengpeng
Published: August 2024

Porous nanofibers are widely used in the fields of water treatment, sensors, energy storage and biomedicine. In this paper, environmentally friendly polylactic acid material was used to achieve controlled fabrication of porous nanofibers using electrostatic spinning technology. Taking fiber diameter and fiber aperture as evaluation indexes, the effects of process parameters on the formation of porous nanofiber were investigated respectively through single-factor experiments, including solution concentration, solvent ratio and feed rate. The results showed that the solution concentration and feed rate were the most important parameters affecting fiber diameter, and the solvent ratio was the most important parameter affecting fiber aperture. The coupling effect of these three parameters was analyzed using response surface experiments and controlled fabrication of porous nanofibers was achieved with diameters ranging from 1.470 to 3.298 μm and apertures ranging from 0.062 to 0.22 μm.
Peculiar spin glass phase emerging in FeCo/FePt driven via nanoconfined crystallographic distortions
Authors: Vashisht Garima , Gandhi Ashish C , Kumar Vishnu , Mathew Arun Jacob , Dong Chung-Li , Chen Chi-Liang , Asokan K , Wu Sheng Yun , Fukuma Y , Annapoorni S
Published: August 2024

We explore the existence of spin glass phase in FeCo/FePt bilayers arising due to disordered ferromagnet. The non-ergodic and highly degenerate landscape of the spin glass phase at low temperature explains the origin of complex magnetic texture in the FeCo/FePt system. Upon cooling the bilayered system, the magnetic texture undergoes spin freezing below 120 K as evident from the bifurcations in zero field cooling and field cooling magnetizations at low magnetic field as a manifestation of broken ergodicity. The uncompensated magnetic moments originating in the spin glass state result in slow time dynamics of thermoremanent magnetization. Consequently, the bilayers demonstrate an intriguing magnetic memory effect in which the magnetic state of the system could be retrieved upon isothermal ageing below 120 K after reversing the temperature cycle. Thermal treatment deteriorates the spin glass behaviour and shows a transition to strong ferromagnetic character in FeCo/FePt bilayers.
A model for the precipitate transformation of Mg–Si-rich clusters into Mg5Si6 β″ in Al–Mg–Si aluminum alloys
Authors: Shan Y V , Redermeier A , Kahlenberg R , Kozeschnik E
Published: August 2024

A model is developed that describes the kinetics of precipitate transformations in the course of natural and artificial aging of Al alloys containing Mg and Si additions. In our approach, the disordered Mg–Si-rich clusters, which form during natural aging in the highly supersaturated Al matrix, can directly transform into the monoclinic Mg5Si6 (β″), without prior dissolution of the clusters and independent nucleation of β″ in the Al matrix. The transformation rate is evaluated with classical nucleation theory (CNT), assuming that the clusters represent an infinitely large matrix phase in which the β″ precipitates can nucleate. The adapted CNT model is described, and the basic features of the precipitate transformation are discussed in a parameter study. The model can also account for the observation that, during natural aging, the parent clusters occur in a variety of Mg to Si ratios, all of which have a characteristic probability of either transforming into the β″ phase or dissolving.
A strategy to fabricate nanostructures with sub-nanometer line edge roughness
Authors: Zhuang Xin , Deng Yunsheng , Zhang Yue , Wang Kaimin , Chen Yulong , Gao Shiyang , Xu Jingfu , Wang Liqiu , Cheng Xing
Published: August 2024

Line edge roughness (LER) has been an important issue in the nanofabrication research, especially in integrated circuits. Despite numerous research studies has made efforts on achieving smaller LER value, a strategy to achieve sub-nanometer level LER still remains challenging due to inability to deposit energy with a profile of sub-nanometer LER. In this work, we introduce a strategy to fabricate structures with sub-nanometer LER, specifically, we use scanning helium ion beam to expose hydrogen silsesquioxane (HSQ) resist on thin SiNx membrane (∼20 nm) and present the 0.16 nm spatial imaging resolution based on this suspended membrane geometric construction, which is characterized by scanning transmission electron microscope (STEM). The suspended membrane serves as an energy filter of helium ion beam and due to the elimination of backscattering induced secondary electrons, we can systematically study the factors that influences the LER of the fabricated nanostructures. Furthermore, we explore the parameters including step size, designed exposure linewidth (DEL), delivered dosage and resist thickness and choosing the high contrast developer, the process window allows to fabricate lines with 0.2 nm LER is determined. AFM measurement and simulation work further reveal that at specific beam step size and DEL, the nanostructures with minimum LER can only be fabricated at specific resist thickness and dosage.
Patterning damage mechanisms for two-dimensional crystalline polymers and evaluation for a conjugated imine-based polymer
Authors: Zhang Bowen , Liu Xiaohui , Li Wei , Clausner André , Conzendorf Sylvia , Liu Jinxin , Posseckardt Juliane , Jost Birgit , Dong Renhao , Feng Xinliang , Liao Zhongquan , Zschech Ehrenfried
Published: August 2024

High-quality patterning determines the properties of patterned emerging two-dimensional (2D) conjugated polymers and is essential for potential applications in future electronic nanodevices. However, the most suitable patterning method for 2D polymers has yet to be determined because we still do not have a comprehensive understanding of their damage mechanisms by visualizing the structural modification that occurs during the patterning process. Here, the damage mechanisms during patterning of 2D polymers, induced by various patterning methods, are unveiled based on a systematic study of structural damage and edge morphology in an imine-based 2D polymer (polyimine). Patterning using a focused electron beam, focused ion beam (FIB) and mechanical carving is evaluated. The focused electron beam successively introduces a sputtering effect, knock-on displacement damage and massive radiolysis with increasing electron dose from

9.46
×

10

7

electrons
 

nm

−
2

to

1.14
×

10

10

electrons
 

nm

−
2

. Successful patterning is enabled by knock-on damage but impeded by carbon contamination beyond a critical sample thickness. A FIB creates current-dependent edge morphologies and extensive damage from ion implantation caused by the tail of the unfocused beam. A precisely controlled tip can tear the polyimine film through grain boundaries and hence create a patterning edge with suitable edge roughness for certain application scenarios when beam damage is avoided. Taking structural damage and the resulting quantitative edge roughness into consideration, this study provides a detailed instruction on the proper patterning techniques for 2D crystalline polymers and paves the way for tailored intrinsic properties and device fabrication using these novel materials.
Advanced physics transposition (APT): a new name for a not-so-new field of research
Authors: Pinochet Jorge
Published: August 2024

Research into educational physics is a field of study that has undergone sustained growth in recent decades. Among the topics addressed in educational physics, there is a relatively new field of research that seeks to make advanced physics accessible to teachers in this area, that is, physics that, due to its novelty and complexity, is beyond the reach of a typical high school teacher. For the reasons discussed in this paper, the name ‘advanced physics transposition’ or APT is suggested for this field of research. The objective of this work is to make a first attempt to systematise this field, to draw attention to the place it occupies, and–no less important–to give it a name that represents the objectives, methods and results that characterise it.
Timing offset calibration for TOF PET using stationary line source scans at multiple positions
Authors: Li Ang , Zhang Xuan , Zhou Xiaoyun , Fang Lei , Hu Junpeng , Li Bingxuan , Zhang Bo , Xie Qingguo , Li Fei , Xiao Peng
Published: August 2024

Background. Accurate timing offset calibration is crucial for time-of-flight (TOF) positron emission tomography (PET) to mitigate image artifacts and improve quantitative accuracy. However, existing methods are often time-consuming, complex, or costly. Objective. This paper presents a method for TOF PET timing offset calibration that eliminates the need for costly equipment, phantoms, short-half-life sources, and precise source positioning. Approach. We estimate channel timing offsets using stationary scans of a 68Ge line source, typically used for routine quality control, at a minimum of three non-coplanar positions, with each position scanned for two minutes. The line source positions are accurately determined by applying a simple algorithm to their reconstructed images, allowing precise calculation of arrival time differences. Channel timing offsets are estimated by solving a least squares problem. This method is assessed through analyses of phantoms and patient images using a RAYSOLUTION DigitMI 930 scanner. Main results. The estimated timing offsets ranged from –500 ps to 500 ps across all channels. Calibration with a minimum of three scanned positions was sufficient to correct these offsets, achieving less than a 1% discrepancy across various metrics of the image quality (IQ) phantom compared to 12 positions. This calibration significantly reduced edge artifacts in TOF reconstruction of both phantoms and patients. Furthermore, the IQ phantom displayed a 14% increase in average contrast recovery, a 61% reduction in average background variability across all spheres, and a 90% reduction in average residual error. Consistent with the phantom results, patient data revealed enhancements in maximum standardized uptake values (SUVmax) from 14% to 55% for lesions measuring 6 mm to 14 mm. The calibration also improved lesion-to-background contrast and eliminated artifacts caused by the spillover effect of the kidneys and bladder. Significance. The proposed method is fast, user-friendly, and cost-effective, effectively improving lesion detection and diagnostic accuracy.
Polarization Study of Swift J151857.0–572147 with IXPE Observation
Authors: Ling Yu-Shan , Xie Fei , Ge Ming-Yu , La Monaca Fabio
Published: August 2024

We present an analysis of the Imaging X-ray Polarimetry Explorer observation from a newly discovered transient source: Swift J151857.0–572147. The obtained polarization degree (PD) and angle are 0.3% ± 0.3% and −24° ± 26° respectively in 2–8 keV within 68% confidence level errors, and polarization results are below MDP99 in all energy bins, with the upper limit on PD of 0.8% in the 2–8 keV energy range. No quasi-periodic oscillations (QPOs) are detected in this observation. The polarization and QPO analyses support the hypothesis that the source was in the high soft state, and the results are consistent with predictions for a thin accretion disk model.
Negative triangularity scenarios: from TCV and AUG experiments to DTT predictions
Authors: Mariani A. , Aucone L. , Balestri A. , Mantica P. , Merlo G. , Ambrosino R. , Bagnato F. , Balbinot L. , Ball J. , Bolzonella T. , Brioschi D. , Casiraghi I. , Castaldo A. , Coda S. , Frassinetti L. , Fusco V. , Happel T. , Hobirk J. , Innocente P. , McDermott R.M. , Muscente P. , Pütterich T. , Sauter O. , Sciortino F. , Vallar M. , Vanovac B. , Vianello N. , Vlad G. , Zimmermann C.F.B. ,   the EUROfusion Tokamak Exploitation team,   the TCV Team,   the ASDEX Upgrade Team
Published: August 2024

Experiments, gyrokinetic simulations and transport predictions were performed to investigate if a negative triangularity (NT) L-mode option for the Divertor Tokamak Test (DTT) full-power scenario would perform similarly to the positive triangularity (PT) H-mode reference scenario, avoiding the harmful edge localized modes (ELMs). The simulations show that a beneficial effect of NT coming from the edge/scrape-off layer (SOL) region

ρ

tor

>
0.9

is needed to allow the actual NT L-mode option to perform like the PT H-mode. Dedicated experiments at TCV and AUG, with DTT-like shapes, show an optimistic picture. In TCV, experiments indicate that even with the relatively small triangularity of the DTT NT scenario, a large beneficial effect of NT comes from the plasma edge and SOL, allowing NT L-modes to outperform PT L-modes with the same power input, reaching the same central pressures as PT H-modes with twice as much applied heating power. For AUG, NT plasmas go into H-mode more easily than for TCV, but always present much smaller pedestals compared with PT plasmas with the same input power, showing a much weaker or absent ELM activity. However, NT has a smaller beneficial effect for AUG than for TCV, with NT pulses outperforming PT pulses with the same input power only for an ECRH-only case with relatively low input power. For the considered AUG cases, PT pulses perform better than NT ones at higher ECRH power or with mixed NBI and ECRH power. Based on this analysis, the NT option is a viable alternative for the DTT full power scenario, providing high performance plasmas with reduced or absent ELMs.
Flat-top plasma operational space of the STEP power plant
Authors: Tholerus E. , Casson F.J. , Marsden S.P. , Wilson T. , Brunetti D. , Fox P. , Freethy S.J. , Hender T.C. , Henderson S.S. , Hudoba A. , Kirov K.K. , Koechl F. , Meyer H. , Muldrew S.I. , Olde C. , Patel B.S. , Roach C.M. , Saarelma S. , Xia G. ,   the STEP team
Published: August 2024

STEP is a spherical tokamak prototype power plant that is being designed to demonstrate net electric power. The design phase involves the exploitation of plasma models to optimise fusion performance subject to satisfying various physics and engineering constraints. A modelling workflow, including integrated core plasma modelling, MHD stability analysis, SOL and pedestal modelling, coil set and free boundary equilibrium solvers, and whole plant design, has been developed to specify the design parameters and to develop viable scenarios. The integrated core plasma model JETTO is used to develop individual flat-top operating points that satisfy imposed criteria for fusion power performance within operational constraints. Key plasma parameters such as normalised beta, Greenwald density fraction, auxiliary power and radiated power have been scanned to scope the operational space and to derive a collection of candidate non-inductive flat-top points. The assumed auxiliary heating and current drive is either from electron cyclotron (EC) systems only or a combination of EC and electron Bernstein waves. At present stages of transport modelling, there is a large uncertainty in overall confinement for relevant parameter regimes. For each of the two auxiliary heating and current drive systems scenarios, two candidate flat-top points have been developed based on different confinement assumptions, totalling to four operating points. A lower confinement assumption generally suggests operating points in high-density, high auxiliary power regimes, whereas higher confinement would allow access to a broader parameter regime in density and power while maintaining target fusion power performance.
A multi-functional intracranial silk-based electronic interface with integrated temperature and pressure sensor
Authors: Tao Chen , Yang Huiran , Zhu Ziyi , Ni Siyuan , Jiang Jianbo , Jiang Wanqi , Zhou Zhitao , Sun Liuyang , Liu Keyin , Tao Tiger H. , Wei Xiaoling
Published: August 2024

The acquisition of multiple brain activity signals, including electrophysiological signals, intracranial pressure (ICP), and intracranial temperature (ICT), is crucial for neuroscience research and the clinical treatment of brain disorders. Additionally, bioelectronic devices intended for in vivo operation require high standards of material safety. In this work, we report a multifunctional monolithic bioelectronic device based on oriented crystallization silk fibroin. The pre-stretched and fixed silk fibroin material exhibits remarkable in vivo stability enhancements. Using Micro Electromechanical System (MEMS) technology, units for the electrophysiological signal, ICP, and ICT collection are efficiently integrated into silk fibroin substrate. This integration is further complemented by an efficient backend connection to construct a system capable of multiple signal acquisitions. Through efficient connection, this multifunctional signal acquisition system can be used for simultaneous neural signal recording and miniaturized high-precision measurements of ICP (pressure coefficient of 48.5 Ω/kPa) and ICT (temperature coefficient of 0.39%). After implantation into the mouse cranium, the device is capable of efficiently synchronizing the acquisition of intracranial electrophysiological signals, intracranial pressure (ICP), and intracranial temperature (ICT) within two days. This class of bioelectronic devices based on silk fibroin effectively expands the efficient application of silk fibroin-based biomaterials.
Comparative Evaluation of Short Circuit Robustness Across Generation of 1.2kV SiC MOSFETs
Authors: Makhdoom Shahid , Ren Na , Wang Ce , Wu Yiding , Wang Hengyu , Sheng Kuang
Published: August 2024

Silicon Carbide (SiC) MOSFETs are efficient alternatives for power electronics, yet concerns persist regarding their short-circuit withstand capability compared to traditional Si IGBTs. Despite the market evolution of 1200V SiC MOSFET generations, a comprehensive comparative analysis of different device types is lacking. This study addresses this gap, comparing five planar and one trench device representing 1st (1G), 2nd (2G), and 3rd generation (3G) products. The SCWT, short circuit energy and short circuit peak power values are also compared. Findings show 3G devices exhibit inferior performance, indicating a compromise between on-state losses reduction and short-circuit ruggedness. The cause behind this seems to be that the smaller die area in 3G hinders heat dissipation during faults, thereby reducing short-circuit withstand time. Furthermore, 2G device display higher resilience at 400V, this advantage diminishes at higher voltages (⩾600V). Notably, 800V 3G devices exhibit survival times as low as 2 μs, with failure analysis identifying gate oxide dielectric breakdown at 400V and thermal runaway at voltages ⩾600V across all.
Fabrication of highly sensitive and fast response flexible humidity sensor based on rGO/MoS2 hybrid composite
Authors: Ke Ningfeng , Ge Gengwu , Ma Hongliang , Ding Jie , Zhang Wendong , Fan Xuge
Published: August 2024

Two-dimensional materials have significant advantages in fabricating humidity sensors due to their high mechanical strength, weak interlayer interactions, high specific surface area surfaces, and abundant active sites, etc. In this paper, flexible humidity sensors based on rGO/MoS2 composite was prepared for humidity sensing. The dispersion of rGO/MoS2 composite was prepared by mixing and dispersing reduced graphene oxide (rGO) and molybdenum disulfide (MoS2). The conductive silver paste was printed onto a PET substrate by screen printing, and then the dispersion of rGO/MoS2 composite was drop-coated onto PET substrate to fabricate the humidity sensor. The prepared humidity sensor has the responsivity of 95% from 23%RH to 85%RH, with the response time of 11 s and recovery time of 14.4 s. This work demonstrates the potential of rGO/MoS2 composites for the application in high-performance humidity sensors.
Manufacture of flexible humidity sensors with high sensitivity and fast response using MoS2/graphene oxide composite
Authors: Ge Gengwu , Ke Ningfeng , Ding Jie , Zhang Wendong , Fan Xuge
Published: August 2024

Humidity monitoring is very necessary for industrial production, medical and health care, environmental monitoring and household use. Resistive humidity sensor is one of common types of humidity sensors due to simple preparation and electrical readout. MoS2, a 2D material, has the great potential to be used for humidity sensing due to its high electrocatalytic activity, large specific surface area, and a wealth of surface-responsive sites. GO (graphene oxide) has excellent hydrophilic properties due to the abundance of oxygen-containing functional groups (including hydroxyl, epoxy, and carboxylic acid groups) on its surface. In addition, sensors based on pure MoS2 or pure GO are limited in either sensitivity or response and recovery time. In this work, the flexible humidity sensor based on MoS2/GO composite films was realized, featuring high responsivity (98%), fast response/recovery time (1.3/12.1s), and good stability.
Microfluidic assay devices integrated with Au nanorods for rapid and sensitive detection of cardiac troponin I
Authors: Xu Xuefeng , Li Guangyang , Xue Lingyue , Xu MingZhu , Hu Sixing , Xiang Anli , Yang Xi , Lu Jiaqi , Cao Zhen
Published: August 2024

We present a microfluidic assay device integrated with Au nanorods for rapid and sensitive detection of Cardiac troponin I (cTnI), the current gold standard biomarker for diagnosing acute myocardial infarction. The Au nanorods, fabricated using oblique angle deposition (OAD), significantly enhance fluorescent signals, thereby eliminating the need for high-resolution lithography technologies. Leveraging this device, rapid and sensitive detection of cTnI is realized with a limit of detection (LOD) of 6.9 pg mL−1 within 6 minutes, referring to a sensitivity enhancement of 4000-fold compared to glass substrates. Given its simple fabrication method, ease of operation, and highly sensitive immunoassay performance, this device holds great potential for clinical and point-of-care testing (POCT) applications.
Angle-Independent Broadband Miniaturized Spectrometers
Authors: Zhang Gongyuan , Ahmed Mian Aizaz , Dong Shurong , Yang Zongyin
Published: August 2024

The miniaturized spectrometers are small and lightweight, which allows for integration into portable analytical instruments and consumer electronics, making them ideal for a wide range of applications, including scientific research, industrial process control, environmental monitoring, and healthcare diagnostics. Compared to other types of grating-based or Fourier-transform spectrometers, filter-based miniaturized spectrometers are relatively simple in design and often more cost-effective to manufacture. However, the spectral accuracy of conventional filter-based miniaturized spectrometers is sensitive to incident light angle. Besides, a large number of filters are required for broadband spectral detection in filter-based spectrometers, which increases cost and complexity. Here, we propose an angle-independent broadband miniaturized spectrometer, where the linear variable Fabry-Perot cavity is introduced to maintain spectral performance over a wide spectral range, and a slit combined with a diffuser is adapted to minimize the sensitivity of spectral accuracy to incident light angle. Our study defines a unique pathway to high-performance miniaturized spectrometers and makes them valuable tools for a wide range of applications requiring compact, cost-effective, and high-performance spectral analysis.
A Highly Sensitive MEMS Three-Dimensional Force Sensor based on Piezoresistive Cantilever with Stress Concentration
Authors: li Aomen , Hou Cheng , Sun Yuyang , Ji Tianci , Liu Huicong , Li Dongsheng
Published: August 2024

This study presents a highly sensitive 3D force sensor based on a piezoresistive cantilever with stress concentration. The sensor achieves precise 3D force detection by integrating a polydimethylsiloxane (PDMS) cap with pyramid microstructures and silicon chip containing four piezoresistive cantilevers with a micro-hole at their root. Finite element simulation validates the superior performance of the micro-hole in enhancing the sensitivity of the force sensor. Compared to a traditional sensor based on a piezoresistive cantilever, the microhole design increases strain in the piezoresistive region of the cantilever by 2 times and the stress by 2.72 times. The proposed sensor exhibits promising potential for applications in various fields, including medical devices, robotics, industrial automation, and others.
A Novel TCAD Methodology of Robustness Evaluation for HV ESD Protection Devices
Authors: Zhang Tianyi , Cui Qiang , Zeng Yuwei
Published: August 2024

Second breakdown current (It2) is an important merit of Electrostatic discharge (ESD) protection devices, and it is especially critical for high voltage ESD design. The device physics involved in ESD phenomena are highly complex as ESD devices operate at high current condition within a short period of time. Technology Computer Aided Design (TCAD) simulation offers faster design optimization and quantitative evaluation of robustness, which can significantly improve ESD device’s robustness. However, an accurate TCAD simulation requires accurate modelling of sophisticated device physics. Due to the ESD’s high stress nature, understanding and modelling of such device physics are non-trivial. We applied TCAD 2D simulation to a high voltage Silicon-controlled Rectifier (SCR), 2D simulation to diode and 3D simulation to diode with different sizes. Based on comparisons of two ESD modes (HBM and CDM) and two transmission line pulses (TLP and VFTLP) simulation data, the simulation method is self-consistent and shows effective It2 prediction ability. The above-mentioned TCAD simulation method can help accelerate design iteration of ESD design and find more optimized ESD device structures.
A Large-FOV and High-Resolution Bionic Eyeball Optical System Based on A Sphere and Curved Imaging Surface
Authors: Wang Chenyu , Yuan Ze , Ye Zhi
Published: August 2024

Bionic eyeballs have consistently received great attention, as it holds potential to restore vision for the visually impaired. To design a bionic eyeball that is closest to the human eye’s performance, scientists have proposed various eyeball models. However, this models all have relatively complex structures. We propose a novel design method for bionic eyeballs, introducing aspheric surface instead of spherical surface, and only need an incident and an imaging surfaces to achieve the imaging function of eyeball. Cleverly, we designate the lens surfaces as the Zernike Fringe Sag surfaces, utilizing its unique properties to obtain the lens capable of clear imaging within 170° Field of View. This design makes the lens size close to the human eye. Compared with traditional large Field of View lens groups, it has a minimalist structure. Additionally, we compare imaging performance of the lens with a curved imaging surface to that of the lens with a flat imaging surface, further demonstrating feasibility of our design. This provides a reference for the practical application of bionic eyeballs.
Combining physical modeling and machine learning for micro-scale modeling of a fuel cell electrode
Authors: Brus Grzegorz
Published: August 2024

Microscale modeling plays a critical role in fuel cell development, offering deep insights into the microscale transport phenomena and electrochemical reactions. This level of detail is essential for optimizing the performance of a single fuel cell, enabling the precise design and improvement of materials and structures at the microscale and consequently enhancing the overall efficiency of a stack. Here, we show a comprehensive transition from white-box models, characterized by their reliance on physical laws, to black-box models exemplified by neural networks, which excel in pattern recognition from provided data without necessitating a clear understanding of the underlying processes. This spectrum encompasses the inherent challenges and merits of both methodologies. While white-box models are recognized for their reliability due to their foundation in mathematical equations that describe physical phenomena, they often require the integration of empirical parameters and are susceptible to experimental errors, much like their black-box counterparts. The core novelty in this study lies in the synergistic integration of these two paradigms, specifically tailored for enhancing the predictive accuracy in solid oxide fuel cell modeling. In this approach, the neural network is employed to replace different parts of the mathematical model, from refining empirical parameters in the electrochemical model to replacing the entire electrochemical model. The adjustment of parameters is conducted by an evolutionary strategy based on the outputs of the mathematical model. The results underscore the superiority of the gray box in achieving higher prediction accuracy and in minimizing the requisite data volume for network training. This presented approach not only bridges the gap between the deterministic clarity of white-box models and the data-driven insights of black-box models but also strategically distributes the computational load between them, thereby offering a promising solution to the prevalent challenges in solid oxide fuel cell modeling.
Development of high hydrogen permselective membranes by using a vapor treatment method
Authors: Ito M , Yabe K , Yano H , Nomura M
Published: August 2024

In recent years, the depletion of energy resources and global warming have led to the promotion of new energy resources. Hydrogen is attracting attention as one of the energy sources for the carbon-neutral society by 2050. Membrane separation is a method for separating and purifying hydrogen. In this study, we focused on developing high hydrogen permselectivity of silica membranes. We investigated the conditions necessary for membrane production to obtain a thin, dense separation layer. The results exhibited that the hydrogen permeation selectivity was enhanced in the silica membrane through the utilization of a 2-step deposition technique, which involves the combination of alternative feed and counter-diffusion chemical vapor deposition (CVD). The H2 permeance achieved by the 2-step method is 1.4×10−6 [mol m−2 s−1 Pa−1], representing 1.4 times higher than that of counter-diffusion CVD. In addition, the permeance ratio, which represents hydrogen selectivity, was significantly enhanced with the 2-step method, with H2/C3H8 = 260, twice as high as with CVD. Elemental mapping analysis of the cross-sectional structure revealed a concentration gradient in the deposited silica within the intermediate layer. This indicates that the silica separation layer may become an asymmetric structure. The 2-step method is expected to yield a thinner dense layer, which could contribute to improved permeance of silica separation membranes by reducing permeation resistance.
Optimization of sol-gel preparation method for Y0.9Ce0.1Mn3+δ to improve the oxygen storage properties
Authors: Ishida K , Mele P , Klimkowicz A
Published: August 2024

In recent years, various countries have started to develop and improve hydrogen technologies to establish a sustainable society. Among them, methods to store hydrogen in solids and later use it as an energy carrier are proposed and the principle of gas storage in solids and its potential for gas separation is of interest. This research primarily focuses on analogues concept of oxygen storage and production using solid oxides. It can be realized using the temperature swing adsorption (TSA) method. TSA relies on the specific properties of the absorbent materials that can reversibly change their oxygen content depending on external conditions like temperature. The absorbent materials are called oxygen storage materials (OSM). The overall cost and efficiency of oxygen production using TSA installations depend on the properties of the OSM materials. Therefore, it is essential to develop and improve the OSMs. The subject of this work is to investigate the different synthesis methods of the already chemically optimized Y0.9Ce0.1MnO3+δ material. Samples were prepared using the sol-gel process that allows for the final sintering to be conducted at the relatively low temperature of 1000 °C or below.
Analysis of combustion models of hydrogen-air mixtures using ANSYS FLUENT
Authors: Wyszyński Patryk , Porowski Rafał
Published: August 2024

This paper details an experimental investigation into flame propagation of a stoichiometric hydrogen mixture within a fixed 40 cm3 volume channel, utilizing ANSYS Fluent for simulation. The geometry was delineated as a 200x20 mm plane, with ignition positioned at the center. Certain input parameters were determined using MATLAB’s Cantera. The study explored different configurations of ANSYS Fluent’s channel combustion models, specifically examining both laminar and turbulent scenarios. Overpressure within the chamber was gauged at points 50 mm from the channel’s center to assess the impact of the relaxation factor on these measurements. These models underwent comparative analysis with actual experimental results, focusing on the highest achieved pressures and the flame’s shape at 1.9 ms, 2.9 ms, and 4.8 ms post-ignition. The findings underscore the complexity of modelling hydrogen mixture combustion in enclosed channels, highlighting the necessity for a specialized approach. Standard modules struggled to accurately replicate pressure variations over time, leading to significant discrepancies between the resulting models.
Comparison of methods for discharging an isochoric compressed air tank in compressed air energy storage systems
Authors: Kubala Piotr , Gryboś Dominik , Markowski Jan , Leszczyński Jacek
Published: August 2024

Renewable energy sources are characterized by intermittent operation, which creates the need to store surplus energy and release it at the time of demand. Energy storage systems that keep energy in compressed air can be a solution to this problem. Therefore, it is necessary to identify the method of releasing compressed air and select the most efficient one. In the study conducted, two particular ways of controlling the expansion of air stored in the tank emerged: control through a cut-off function of air supplied into cylinder and through the use of pressure regulator. To indicate which solution is more cost-effective from an energy point of view, a series of simulations were carried out using the Matlab environment. Operation with the highest efficiency and with the highest sustainability was achieved using a PID (proportional-integral-derivative) controller and a function controlling the level of opening of the valve passing air to the expander. The method considering the presence of the buffer tank provided rotation stability in a much shorter system operation time, while the baseline scenario (which did not include any form of system control) was characterized by instability, short operation time and low efficiency.
An underground pipeline relocation decision support system based on BIM and GIS integration
Authors: Ma Fei , Gao Yang , Zhang Guien , Huang Can , Chen Wenkai
Published: August 2024

This study introduces a rapid decision-support system for underground pipeline relocation, leveraging the synergistic capabilities of Building Information Modeling (BIM) and Geographic Information Systems (GIS). The amalgamation of BIM and GIS technologies within the system facilitates comprehensive information management and analysis. To validate the system’s practicality, dedicated software applications have been developed to streamline data collection, model generation, and data fusion. In the data collection phase, a mobile application has been designed to efficiently acquire standardized physical exploration data. In the design phase, we have implemented an automated pipeline modeling process, utilizing the physical exploration data through our in-house Revit plug-in. Concurrently, the plug-in enables clash detection and distance analysis. Subsequently, the model can be seamlessly transferred to our custom-built integration platform, which is founded on ArcGIS. Within this platform, the integration of the BIM model with GIS can be visually represented. Furthermore, it provides tools for analyzing project quantity and monitoring project progress. The integrating proposed system and software enhances the efficiency of underground pipeline relocation and augments decision-making capabilities.
Optimization of image style transfer algorithm based on CycleGAN
Authors: Xie Weiran
Published: August 2024

In response to the current problems of uneven quality of images generated by the CycleGAN algorithm, low learning efficiency, instability of training models, and insufficient diversity in generation quality, as well as the violation of perception and aesthetics between images and humans after transfer. This article proposes a CycleGAN model that can generate images with better quality and fuller colors to address the aforementioned issues. This model incorporates a globally connected residual network with self-attention mechanism and improves the network structure of the generator and discriminator to improve the quality of generated images and solve the training imbalance problem caused by the original model. This article uses deep learning frameworks based on Python 3.8, Pytorch 1.10.0, and cuda 1.11.0 for experimental training. The experimental results show that the improved CycleGAN model generates better image quality and higher color saturation. Adding self-attention mechanism can indeed better grasp the degree of restoration of original image details and produce more realistic effects. However, further exploration is needed in terms of training efficiency and generated image clarity.