Integrated power electronics module based on chip scale packaged power devices

High performance can be obtained for the integrated power electronics module（IPEM） by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM （HB-IPEM）, consisting of two chip scale packaged MOSFETs and the corresponding gate driver and protection circuits, is fabricated at the laboratory. The reliability of the IPEM is controlled from the shape design of solder joints and the control of assembly process parameters. The parasitic parameters are extracted using Agilent 4395A impedance analyzer for building the parasitic parameter model of the HB- IPEM. A 12 V/3 A output synchronous rectifier Buck converter using the HB-IPEM is built to test the electrical performance of the HB-IPEM. Low voltage spikes on two MOSFETs illustrate that the three-dimensional package of the HB-IPEM can decrease parasitic inductance. Temperature distribution simulation results of the HB-IPEM using FLOTHERM are given. Heat dissipation of the solder joints makes the peak junction temperature of the chip drop obviously. The package realizes three-dimensional heat dissipation and has better thermal management.

Constructing Large Scale Cohort for Clinical Study on Heart Failure with Electronic Health Record in Regional Healthcare Platform:Challenges and Strategies in Data Reuse

Regional healthcare platforms collect clinical data from hospitals in specific areas for the purpose of healthcare management.It is a common requirement to reuse the data for clinical research.However,we have to face challenges like the inconsistence of terminology in electronic health records (EHR) and the complexities in data quality and data formats in regional healthcare platform.In this paper,we propose methodology and process on constructing large scale cohorts which forms the basis of causality and comparative effectiveness relationship in epidemiology.We firstly constructed a Chinese terminology knowledge graph to deal with the diversity of vocabularies on regional platform.Secondly,we built special disease case repositories (i.e.,heart failure repository) that utilize the graph to search the related patients and to normalize the data.Based on the requirements of the clinical research which aimed to explore the effectiveness of taking statin on 180-days readmission in patients with heart failure,we built a large-scale retrospective cohort with 29647 cases of heart failure patients from the heart failure repository.After the propensity score matching,the study group (n=6346) and the control group (n=6346) with parallel clinical characteristics were acquired.Logistic regression analysis showed that taking statins had a negative correlation with 180-days readmission in heart failure patients.This paper presents the workflow and application example of big data mining based on regional EHR data.

Electronic Cigarette Use Scale: Development and evaluation of a measure among Chinese students

Objective:To develop the Electronic Cigarette Use Scale(ECUS)based on social cognitive theory and test its reliability and validity,so as to provide a scientific tool for evaluating the use of e-cigarette smokers in China.Methods:Based on the review of social cognitive theory and literature analysis,the item pool of ECUS was constructed to form the initial version.From January to March in 2022,using the convenient sampling method,electronic questionnaires were distributed to college students in Guangdong Province through the questionnaire star platform,and a total of 1047 valid questionnaires were collected for item screening.The total sample was randomly divided into sample 1(n=517)and sample 2(n=530)for Exploratory Factor Analysis(EFA)and Confirmatory Factor Analysis(CFA)respectively to further test the reliability and validity of the scale and finally form a 24-item scale.Results:The formal ECUS included 24 items,6 factors were extracted by EFA,and the cumulative explanatory variance was 72.774%.CFA showed that the goodness-of-fit indices were acceptable:χ^(2)/df=2.61,CFI=0.938,TLI=0.928,RMSEA=0.055,90%CI(0.050,0.061),SRMR=0.046,AIC=34694.405,BIC=35036.235.The Cronbach’saof the 24-item scale was 0.898,and the Cronbach’saof each dimension was between 0.839 and 0.954.Both convergent validity and discriminant validity reached the standard.Conclusion:The 24-item ECUS developed in this study has been tested with good reliability and validity and is suitable for evaluating the use of e-cigarette smokers in China.

Relativistic Multichannel Theory:Scaling Behavior of Multichannel Quantum Defect Theory Parameters(μ_(α),U_(iα)) Along the Ne-Like Iso-electronic Sequence

The compact physical parameters(μ_(α),U_(iα))in multichannel quantum defect theory(MQDT)can be directly calculated with relativistic multichannel theory(RMCT).Here we report a systematic study of the MQDT parameters(fiay Uia)with RMCT along the Ne-like iso-electronic sequence(including Ca^(10+),Fe^(16+),Ge^(22+),Ag^(37+) ions).We find that the physical parameters(μ_(α),U_(iα))show a very interesting scaling behavior along the iso-electronic sequence.

Recent advances on thermal analysis of stretchable electronics

Stretchable electronics, which offers the performance of conventional wafer-based devices and mechan- ical properties of a rubber band, enables many novel applications that are not possible through conven- tional electronics due to its brittle nature. One effective strategy to realize stretchable electronics is to design the inorganic semiconductor material in a stretchable format on a compliant elastomeric substrate. Engineering thermal management is essential for the development of stretchable electronics to avoid adverse thermal effects on its performance as well as in applications involving human body and biological tissues where even 1-2℃ temperature increase is not allowed. This article reviews the recent advances in thermal management of stretchable inorganic electronics with focuses on the thermal models and their comparisons to experiments and finite element simulations.

Visualization of atomic scale reaction dynamics of supported nanocatalysts during oxidation and ammonia synthesis using in-situ environmental(scanning) transmission electron microscopy

Reaction dynamics in gases at operating temperatures at the atomic level are the basis of heterogeneous gas-solid catalyst reactions and are crucial to the catalyst function.Supported noble metal nanocatalysts such as platinum are of interest in fuel cells and as diesel oxidation catalysts for pollution control,and practical ruthenium nanocatalysts are explored for ammonia synthesis.Graphite and graphitic carbons are of interest as supports for the nanocatalysts.Despite considerable literature on the catalytic processes on graphite and graphitic supports,reaction dynamics of the nanocatalysts on the supports in different reactive gas environments and operating temperatures at the single atom level are not well understood.Here we present real time in-situ observations and analyses of reaction dynamics of Pt in oxidation,and practical Ru nanocatalysts in ammonia synthesis,on graphite and related supports under controlled reaction environments using a novel in-situ environmental(scanning) transmission electron microscope with single atom resolution.By recording snapshots of the reaction dynamics,the behaviour of the catalysts is imaged.The images reveal single metal atoms,clusters of a few atoms on the graphitic supports and the support function.These all play key roles in the mobility,sintering and growth of the catalysts.The experimental findings provide new structural insights into atomic scale reaction dynamics,morphology and stability of the nanocatalysts.

Modeling and Experimental Validation of the Electron Beam Selective Melting Process

Electron beam selective melting （EBSM） is a promising additive manufacturing （AM） technology. The EBSM process consists of three major procedures：（1） spreading a powder layer, （2） preheating to slightly sinter the powder, and （3） selectively melting the powder bed. The highly transient multi-physics phenomena involved in these procedures pose a significant challenge for in situ experimental observation and measurement. To advance the understanding of the physical mechanisms in each procedure, we leverage high- fidelity modeling and post-process experiments. The models resemble the actual fabrication procedures, including （1） a powder-spreading model using the discrete element method （DEM）, （2） a phase field （PF） model of powder sintering （solid-state sintering）, and （3） a powder-melting （liquid-state sintering） model using the finite volume method （FVM）. Comprehensive insights into all the major procedures are provided, which have rarely been reported. Preliminary simulation results （including powder particle packing within the powder bed, sintering neck formation between particles, and single-track defects） agree qualitatively with experiments, demonstrating the ability to understand the mechanisms and to guide the design and optimization of the experimental setup and manufacturing process.

Statistical properties of kinetic-scale magnetic holes in terrestrial space

Kinetic-scale magnetic holes(KSMHs)are structures characterized by a significant magnetic depression with a length scale on the order of the proton gyroradius.These structures have been investigated in recent studies in near-Earth space,and found to be closely related to energy conversion and particle acceleration,wave-particle interactions,magnetic reconnection,and turbulence at the kineticscale.However,there are still several major issues of the KSMHs that need further study—including(a)the source of these structures(locally generated in near-Earth space,or carried by the solar wind),(b)the environmental conditions leading to their generation,and(c)their spatio-temporal characteristics.In this study,KSMHs in near-Earth space are investigated statistically using data from the Magnetospheric Multiscale mission.Approximately 200,000 events were observed from September 2015 to March 2020.Occurrence rates of such structures in the solar wind,magnetosheath,and magnetotail were obtained.We find that KSMHs occur in the magnetosheath at rates far above their occurrence in the solar wind.This indicates that most of the structures are generated locally in the magnetosheath,rather than advected with the solar wind.Moreover,KSMHs occur in the downstream region of the quasi-parallel shock at rates significantly higher than in the downstream region of the quasi-perpendicular shock,indicating a relationship with the turbulent plasma environment.Close to the magnetopause,we find that the depths of KSMHs decrease as their temporal-scale increases.We also find that the spatial-scales of the KSMHs near the subsolar magnetosheath are smaller than those in the flanks.Furthermore,their global distribution shows a significant dawn-dusk asymmetry(duskside dominating)in the magnetotail.

Optimization of Electron Density and Temperature Profiles in Tokamaks via Safety Factor Profile

The turbulent particle and thermal transport scaling laws are derived by means of Lagrangian invariant of trapped electron dynamics in tokamaks,which are in good agreement with experimental results.On the basis of the two scaling laws,it is proposed that the optimization of electron density and temperature profiles can be achieved by designing a desirable safety factor profile.

Equivalent electron correlations in nonsequential double ionization of noble atoms

Electron correlation is encoded directly in the distribution of the energetic electrons produced in a recollision-impact double ionization process, and varies with the laser field and the target atoms. In order to get equivalent electron correlation effects, one should enlarge the laser intensity cubically and the laser frequency linearly in proportion to the second ionization potentials of the target atoms. The physical mechanism behind the transform is to keep the ponderomotive parameter unchanged when the laser frequency is enlarged.

Ultrastructural Findings, at Micrometric and Nanometric Scales, in Rectal and Muscular Mucosa of Patients with HIV/AIDS and Anorectal Pathology

Objective: To determine the ultrastructural findings on Rectal Mucosa (RM) of patients with HIV/AIDS and anorectal pathologies (ARP), at micrometric and nanometric scales. Materials and methods: 5 patients were evaluated, 18 - 55 years old, with ARP (HIV co-infection with HPV, n = 4, and HIV-negative patient with HPV infection) (control n = 1), who were referred to the Coloproctology Unit of the HUC, and subjected to rectoscopy and biopsy. RM samples were identified, placed in a sterile plastic bottle with 1 mL of 2% glutaraldehyde and immediately transported for routine processing of fine cut (60 - 90 nm) to be evaluated via Transmission Electron Microscopy (TEM). They were fixed with Karnovsky solution with Millonig phosphate buffer (pH 7.4 and 320 mOsm) and post-fixed with OsO4 under the same conditions of pH and osmolarity. Results: Ultrastructural findings, at 10−6 scale: 1) Intestinal mucosa: vacuoles of mucus of different sizes that seem to be fused. 2) Smooth muscle cells: loss of definition of contractile myofilaments mass. 3) Unmyelinated axons and terminals of Schwann cells (SC): Edema and loss of their plasma membranes in some areas of association with axon terminals as well as abundant collagen fibers associated with SC. Ultrastructural findings, at 10−9 scale: 1) Smooth muscle cells: folded wrapper cores and edema of mitochondria and rough endoplasmic reticulum cisterns (RER). 2) Myelinated axon terminals: Loss of synaptic vesicles. 3) Fibroblasts: One observes mitochondria and cisterns of RER with alterations. All these alterations can generate intestinal and anorectal dysfunction in these patients. Conclusions: The HIV causes changes in rectal and muscular mucosa despite HAART treatment with undetectable viral load.

FreescaleMC68HC908QY4单片机在电子秤中的应用

给出了一种以FreescaleMC68HC908QY4为核心的新型电子秤的设计方案,较详细的说明了FreescaleQY4单片机内部结构、A/D转换原理和应用场合。

Electrical Characteristics,Electrode Sheath and Contamination Layer Behavior of a Meso-Scale Premixed Methane-Air Flame Under AC/DC Electric Fields

Electrical characteristics of a nozzle-attached meso-scale premixed methane-air flame under low-frequency AC （0-4300 V, 0-500 Hz） and DC （0-3300 V） electric fields were studied. I-V curves were measured under different experimental conditions to estimate the magnitude of the total current 10^0-10^2μA, the electron density 10^15-10^16 m^-3 and further the power dissipation 〈 0.7 W in the reaction zone. At the same time, the meso-scale premixed flame conductivity 10^-4-10^-3 Ω^-1. m^-1 as a function of voltage and frequency was experimentally obtained and was believed to represent a useful order-of magnitude estimate. Moreover, the influence of the collision sheath relating to Debye length （31-98 μm） and the contamination layer of an active electrode on measurements was discussed, based on the combination of simulation and theoretical analysis. As a result, the electrode sheath dimension was evaluated to less than 0.5 mm, which indicated a complex effect of the collision sheath on the current measurements. The surface contamination effect of an active electrode was further analyzed using the SEM imaging method, which showed elements immigration during the contamination layer formation process.

STUDIES ON SILICA-SCALED CHRYSOPHYTES FROM FUJIAN PROVINCE, CHINA

In 19 phytoplankton samples collected from 14 water bodies in the southeastern part of China and examined by electron microscopy, 27 taxa of silica-scaled chrysophytes (8 of them belonging to the Chrysophyceae and 19 to the Synuriphyceae) were found. All these taxa are new to Fujian province;24 of them were previously found in China, but 3, viz. Chrysosphaerella septispina, Mallomonas rasilis and M. guttata var. simplex are new to China. M. guttata var. simplex has only been reported from the Ontario region, Canada. The silica-scaled chrysophyte flora and their geographical distribntion in thisregion are discussed.

As Could We Assure Safety in Large-Scale Manufacturing of Nanoparticles for the Biomedical Use

Nanoparticles provide great advantages but also great risks. Risks associating with nanoparticles are the problem of all technologies, but they increase in many times in nanotechnologies. Adequate methods of outgoing production inspection are necessary to solve the problem of risks, and the inspection must be based on the safety standard. Existing safety standard results from a principle of “maximum permissible concentrations or MPC”. This principle is not applicable to nanoparticles, but a safety standard reflecting risks inherent in nanoparticles doesn’t exist. Essence of the risks is illustrated by the example from pharmacology, since its safety assurance is conceptually based on MPC and it has already come against this problem. Possible formula of safety standard for nanoparticles is reflected in many publications, but conventional inspection methods cannot provide its realization, and this gap is an obstacle to assumption of similar formulas. Therefore the development of nanoparticle industry as a whole (also development of the pharmacology in particular) is impossible without the creation of an adequate inspection method. There are suggested new inspection methods founded on the new physical principle and satisfying to the adequate safety standard for nanoparticles. These methods demonstrate that creation of the adequate safety standard and the outgoing production inspection in a large-scale manufacturing of nanoparticles are the solvable problems. However there is a great distance between the physical principle and its hardware realization, and a transition from the principle to the hardware demands great intellectual and material costs. Therefore it is desirable to call attention of the public at large to the necessity of urgent expansions of investigations associated with outgoing inspections in nanoparticles technologies. It is necessary also to attract attention, first, of representatives of state structures controlling approvals of the adequate safety standard to this problem, since it is impossible to compel producers providing the safety without the similar standard, and, second, of leaders of pharmacological industry, since their industry already entered into the nanotechnology era, and they have taken an interest in a forthcoming development of inspection methods.

基于物联网技术的鸡智能育种平台研究与应用

为解决鸡规模化生产过程中个体精细化数据采集难度大、成本高、选育配种效率低等问题,研究设计基于物联网的包括适用于鸡全生命周期佩戴的电子标签、自动称重台、移动终端采集系统及鸡智能育种管理系统的鸡智能育种平台。结果显示:该平台实现鸡育雏、育成、产蛋到淘汰各阶段个体外貌、生产性能、调群等数据的精准采集,以及系谱跟踪、报表生成、智能选配等功能;较传统铝质翅标佩戴效率提升40%,个体身份识别正确率超过98%,产蛋、体重、外貌等数据采集准确率超过99%,通过种鸡智能选种选配模型实现了种鸡的快速优选,避免近亲繁殖。研究表明,建立的鸡智能育种平台能满足不同规模养殖企业的生产需求,有效减少人力成本、提升育种效率。

计及多重差异的交直流混合多能微网多时间尺度优化调度

近年来,可再生能源发电、热电联产、储能和电力电子变压器(PET)等技术发展迅速,有利于构建多能互补、清洁高效的交直流混合多能微网(MEMG),但不成熟的PET模型和复杂的不确定性为系统的优化调度带来了挑战。为此,首先构建了一种基于三级式PET的交直流混合MEMG结构,建立了包括PET在内的设备模型和不确定性模型;其次,提出了计及多重差异的MEMG多时间尺度优化调度策略,明确了日前-日内-实时三时间尺度调度的协调机制,其中,多重差异包含需求响应资源、系统调度目标和源荷预测精度在时间尺度上的差异,以及不同能量的响应特性差异;再次,建立了对应的多时间尺度优化调度模型,包括日前鲁棒机会约束优化模型、日内随机优化模型和实时分层滚动修正模型,并在日前调度中,改进了传统储能和电热耦合设备的备用模型,设计了基于PET的交直流系统备用共享机制,将调度模型转换为混合整数线性规划模型,给出了利用CPLEX求解器求解多时间尺度调度模型的步骤;最后,通过算例分析表明,所提调度策略可以通过逐级修正调度计划应对不确定性,且所设计备用方案兼具可靠性和灵活性。

体电子显微学前沿

电子显微成像技术的快速发展使得对完整细胞、组织乃至整个机体进行高分辨三维结构解析研究成为可能,这些可进行大尺度生物样品三维结构研究的电子显微成像技术统称为体电子显微学技术(volume electron microscopy,vEM)。近年来,v EM在研究尺度、分辨率、吞吐量和易用性等方面发展迅速,在整个生命科学领域的应用呈爆炸式增长,该技术因此被《自然》(Nature)评为2023年最值得关注的七项前沿技术之一。然而,vEM相关技术的发展和应用在国内起步较晚,亟待进一步推广。本综述涵盖了vEM的发展历程、技术分类、样品制备、数据收集、图像处理等全方位的内容,便于生命科学、医学等领域研究人员去了解、学习、应用和进一步发展该技术。

基于自然图像模型微调的小鼠脑部电镜图像实例分割

分割模型的准确性和鲁棒性是小鼠脑电镜图像处理中的主要考虑因素。针对电镜图像的技术特点,提出了高度稳健的二维分割算法,准确识别每张切片中各物体的形态结构。本文提出了基于大型自然图像模型的主干网络微调的大尺度二维电镜图像分割模型EM-SAM,用于脑部电镜图像中的实例分割。模型主干网络采用大型自然图像模型SAM中的已训练完成的图像编码器,在电镜图像处理任务中最大化模型提取图像特征的能力。此外,模型采用了U型的解码器设计,并通过小鼠脑电镜图像分割任务进行微调。实验结果表明:在公开数据集SNEMI3D中A-Rand可达到0.054;在公开数据集MitoEM中AP-50和AP-75分别可达到0.883,0.604。EM-SAM在电镜图像神经分割任务中准确性高、鲁棒性强,并且可针对不同任务进行微调。

基于COSMIC掩星观测的顶部电离层标高特征分析

顶部电离层是指F2层电子密度最大值所在高度以上的电离层区域。掩星观测能够提供地面到低轨卫星轨道高度处的整个电离层电子密度剖面,对于顶部电离层的研究具有重要作用。标高是构建顶部以上电离层电子密度剖面模型的重要参数。本文使用2007—2020年的气象、电离层和气候星座观测系统(Constellation Observing System for Meteorology,Ionosphere and Climate,COSMIC)掩星观测数据,提取有效电子密度剖面数据的顶部标高,分析了其随地方时、季节、经纬度和太阳活动水平的变化特性。结果表明:顶部标高具有明显的日变化和季节变化规律,并且表现出强烈的太阳活动依赖性;顶部标高在纬度上的变化强烈依赖于地方时,同时在东西经向上表现出明显的波状结构,且这种经度波状结构在南北半球具有不同的形态;顶部标高在夏季半球具有显著的东西经向差异,南半球夏季更为明显。