三相CLLC谐振变换器磁集成平面变压器设计与优化

三相CLLC谐振变换器凭借其高效率、大容量、低器件应力等优势而受到广泛关注。然而,多相结构的磁性元件数量多、体积大,是制约功率变换器尺寸的主要因素。随着宽禁带(WBG)半导体器件的出现,功率变换器的开关频率显著提高,这也为印制电路板(PCB)绕组的使用提供了有利条件。与传统绕线式绕组相比,PCB绕组的扁平特性更适用于平面磁性元件。此外,由于高频带来的低电感需求也使得基于PCB绕组的平面磁性元件更有利于实现集成。该文提出一种新型的基于PCB绕组的电感和变压器的集成结构,详细分析磁心结构的磁路模型,并给出集成磁件的优化设计方法,最后通过搭建一台基于SiC器件的800 V/10 kW的实验样机进行验证。实验结果表明,该集成方案可有效减小变换器的体积和损耗,具有高功率密度和高效率。

基于GaN器件与磁集成技术的车载充电机实验平台研究

随着新能源汽车的普及,对车载充电机的要求越来越高。为了有效提升整机效率和功率密度,将GaN器件与磁集成技术应用于车载充电机,进行了实验平台研究。基于GaN器件设计了两级式车载充电机拓扑结构与外围电路,通过制作磁集成平面变压器,优化了CLLC变换器,完成了整机控制程序设计及2kW车载充电机实验样机搭建,并对样机进行了实验测试与波形分析。实验结果表明,实验样机具有良好的稳态特性与动态特性,整机功率因数在0.98以上,满载峰值效率达到95.22%。该平台能够帮助学生加深对电力电子技术的认识,掌握新型电力电子器件的特性及应用,锻炼实践操作能力,提高相关课程的教学质量。

Building up a general selection strategy and catalytic performance prediction expressions of heteronuclear double-atom catalysts for N_(2)reduction

The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and homonuclear double-atom catalysts have been preliminarily explored,but the relationship between the inherent properties and catalytic activity of heteronuclear double-atom catalysts with better performance remains unclear.Therefore,it is very significant to explore the prediction expressions of catalytic activity of heteronuclear double-atom catalysts based on their inherent properties and find the rule for selecting catalytic centers.Herein,by summarizing the free energy for the key steps of NRR on 55 catalysts calculated through the first-principle,the expressions of predicting the free energy and the corresponding descriptors are deduced by the machine learning,and the strategy for selecting the appropriate catalytic center is proposed.The selection strategy for the central atom of heteronuclear double-atom catalysts is that the atomic number of central B atom should be between group VB and VIIIB,and the electron difference between central A atom and B atom should be large enough,and the selectivity of NRR or hydrogen evolution reaction(HER)could be calculated through the prediction formula.Moreover,five catalysts are screened to have low limiting potential and excellent selectivity,and are further analyzed by electron transfer.This work explores the relationship between the inherent properties of heteronuclear double-atom catalysts and the catalytic activity,and puts forward the rules for selecting the heteronuclear double-atom catalytic center,which has guiding significance for the experiment.

On Fixed-Parameter Solvability of the Minimax Path Location Problem

The minimax path location problem is to find a path P in a graph G such that the maximum distance d_(G)(v,P)from every vertex v∈V(G)to the path P is minimized.It is a well-known NP-hard problem in network optimization.This paper studies the fixed-parameter solvability,that is,for a given graph G and an integer k,to decide whether there exists a path P in G such that max v∈V(G)d_(G)(v,P)≤k.If the answer is affirmative,then graph G is called k-path-eccentric.We show that this decision problem is NP-complete even for k=1.On the other hand,we characterize the family of 1-path-eccentric graphs,including the traceable,interval,split,permutation graphs and others.Furthermore,some polynomially solvable special graphs are discussed.

考虑频率死区的储能单元协同控制策略

新能源并网比例的不断攀升降低了电力系统惯量,导致系统调频能力下降。为此,开展了储能参与调频的研究。储能参与调频受到单元数量、荷电状态(state of charge,SOC)、充放电策略等因素影响,提出一种考虑频率死区的储能单元协同控制策略,根据SOC一致性对储能单元进行分组,不同组别单独执行下垂控制或虚拟惯量控制,简化出力控制指令。依据系统频率偏差或频率变化率进行控制指令切换,并分别设置频率偏差和频率变化率死区,以减少小扰动干扰导致储能系统频率充放电。基于Matlab/Simulink进行仿真验证,结果表明:所提控制策略简单便于执行,能够快速响应调频需求,并且能保证储能电池使用寿命。

烟曲霉相关C型凝集素受体研究进展

烟曲霉(Aspergillus fumigatus,A.fumigatus)是最普遍的空气传播真菌病原体,可导致免疫功能低下患者发生致命的侵袭性曲霉病。对病原体与宿主免疫系统的相互作用过程的了解是理解其致病性的关键。通过保守的跨膜或可溶性的模式识别受体(pattern recognition receptor,PRRs)识别病原体表面上的保守分子结构,称为病原体相关分子模式(pathogen associated molecular patterns,PAMPs)。C型凝集素受体(C-type lectin receptors,CLRs)是PRRs中主要受体家族之一,CLRs可以通过C型凝集素样结构域(Ctype lectin-like domains,CTLDs)来识别β-葡聚糖、甘露糖、几丁质等真菌细胞壁成分,从而诱导固有免疫和获得性免疫来清除病原体。目前烟曲霉中所涉及的CLRs主要为Dectin-1、Dectin-2、MelLec、DC-SIGN等,这些CLRs在宿主细胞识别烟曲霉中起着至关重要的作用,并且针对Dectin-1及Dectin-2已开发出新型抗烟曲霉药物。因此为了进一步了解与烟曲霉相关的各类CLRs的作用机制及其相关信号通路,为开发新型抗真菌药物提供一种新思路,文章对与烟曲霉相关的CLRs最新研究进展进行了综述。

“Capture-activation-recapture” mechanism-guided design of double-atom catalysts for electrocatalytic nitrogen reduction

Compared with the traditional industrial nitrogen fixation, electrocatalytic methods, especially those utilizing double-atom catalysts containing nonmetals, can give good consideration to the economy and environmental protection. However, the existing “acceptance-donation” mechanism is only applicable to bimetallic catalysts and nonmetallic double-atom catalysts containing boron atoms. Herein, a novel “capture-activation-recapture” mechanism for metal-nonmetal double-atom catalyst is proposed to solve the problem by adjusting the coordination environments of nonmetallic atoms and utilizing the activation effect of metal atoms on nitrogen. Based on this mechanism, the nitrogen reduction reaction (NRR) activity of 48 structures is calculated by density functional theory calculation, and four candidates are selected as outstanding electrocatalytic nitrogen reduction catalysts: Si-Fe@NG (U_(L) = –0.14 V), Si-Co@NG (U_(L)= –0.15 V), Si-Mo@BP1 (U_(L) = 0 V), and Si-Re@BP1 (U_(L) = –0.02 V). The analyses of electronic properties further confirm “capture-activation-recapture” mechanism and suggest that the difference in valence electron distribution between metal and Si atoms triggers the activation of N≡N bonds. In addition, a machine learning approach is utilized to generate an expression and an intrinsic descriptor that considers the coordination environment to predict the limiting potential. This study offers profound insight into the synergistic mechanism of TM and Si for NRR and guidance in the design of novel double-atom nitrogen fixation catalysts.

Migratory properties of cultured olfactory ensheathing cells by single-cell migration assay

嗅觉的 ensheathing 房间(OEC ) 是有 axonal 的 glial 房间的一种唯一的类型支持生长的性质。OEC 移植作为 axonal 损害和 demyelinating 疾病的有希望的试验性的治疗出现了。然而， OEC 的一些基本细胞的性质仍然保持不清楚。在这研究，我们发现不同 OEC 候补选手人口基于单个孤立的房间的微速摄影的成像展出了不同迁移的性质，可能由于他们的不同细胞骨架组织。而且， OEC 潜水艇人口在单个房间的迁居试金显示了不同吸引人的迁移的回答到 lysophosphatidic 酸(LPA ) 的一个坡度。最后，我们发现了人口自发地转变了成对方的那个 OEC 代用品。一起，这些结果示威，第一次到我们的知识，不同 OEC 潜水艇人口显示不同迁移的性质试管内并且提供新证据当一个单个房间与韧性的功能的显型打字，支持 OEC 的观点。

Spatial and diel variations of the prokaryotic community in the Phaeocystis globosa blooms area of Beibu Gulf,China

While prokaryotes play key roles in nutrient cycling and energy flow during Phaeocystis globosa blooms,the information on the spatial and diel temporal distribution of the prokaryotic community during Phaeocystis blooms remains scarce.In January 2019,we used high-throughput sequencing of the 16S rRNA gene to explore the spatial and diel variations of particle-attached(PA)and free-living(FL)prokaryotic communities during the blooming phase of P.globosa in Beibu Gulf,Guangxi,China.The results suggested a significant spatial variation pattern in the horizontal distribution of prokaryotic communities,while there was no significant difference in the vertical direction.Both spatial distance and environmental variables shaped the horizontal distribution of the prokaryotic community structure,while environmental variables,particularly the abundance of P.globosa colony and Chl a,showed more significant influence and were closely related to the structure and variation of the prokaryotic community.Strong vertical mixing of the water column disrupted the vertical structure heterogeneity of the prokaryotic community in winter.There were significant differences in the diel samples of PA prokaryotic communities,but not in the FL prokaryotic communities.Nitrate,ammonium and the abundance of P.globosa colony were the key environmental variables impacting the diel variations of prokaryotic communities over the sampling period.The present study provided valuable information to depict the spatial-temporal variations of the microbial community and its association with environmental parameters during P.globosa bloom in the tropical gulf.

电火工品换能元增效技术研究进展

作为电火工品的核心部件,换能元直接影响着电火工品的安全性和可靠性。电火工品结构微型化、换能信息化、序列集成化的发展趋势对于换能元提出了更高的技术要求。如何实现在低能量刺激下可靠发火,同时提升换能元的点火输出能力,即如何实现电火工品换能元的效能提升成为目前火工品换能器件研究的重要课题之一。为此,本文从换能元基底和电阻材料的优选、发火结构优化设计、自含能一体化增效以及含能薄膜复合增效等角度,综述了近年来电火工品换能元低能发火与输出增效的最新研究进展。在此基础上,讨论了未来开展换能元增效研究的重点:建立换能元材料参数基因库,借助机器学习算法等手段提高换能元发火结构优化设计的效率,针对宽带隙半导体材料等开展新换能体制的基础研究,探索含能金属有机骨架材料(Metal-Organic Frameworks,MOFs)、含能钙钛矿等新型含能薄膜材料在换能元上的集成制备。

Dynamic contrast-enhanced MRI parameters of breast cancer tissue and their correlation with cancer cell proliferation and invasion

Objective:To study the dynamic contrast-enhanced MRI (DCE-MRI) parameters of breast cancer tissue and their correlation with cancer cell proliferation and invasion.Methods: A total of 92 patients with breast mass who underwent surgical treatment in our hospital between July 2012 and June 2016 were collected as research subjects. According to the results of pathological examination, the patients were divided into breast adenoma group (n=52) and breast cancer group (n=40). DCE-MRI parameter levels of breast mass were analyzed between two groups of patients, and the mRNA expression of proliferation and invasion genes in tumor samples were compared. Pearson test was used to further evaluate the relationship between the DCE-MRI parameter levels of breast cancer tissue and the malignant degree of tumor.Results:The DCE-MRI parameter TTP level in breast cancer group was lower than that in breast adenoma group while EER and SLOPE levels were higher than those in breast adenoma group. Proliferation genes C6orf106, HMGB2, ETS-1 and BRG1 mRNA expression in tumor tissue of breast cancer group were higher than those of breast adenoma group, and invasion genes ADAM9, Ezrin and Nanog mRNA expression were higher than those of breast adenoma group while CRM197 and EBP50 mRNA expression were lower than those of breast adenoma group. The Pearson test showed that the DCE-MRI parameter levels of breast cancer tissues were directly correlated with the mRNA expression of proliferation and invasion genes.Conclusion:DCE-MRI parameter levels are abnormal in breast cancer tissues, and the abnormal degree is directly correlated with the malignant biological behavior of tumor cells.

2022年度胰腺癌研究及诊疗新进展

胰腺癌是中国致死人数排名第六的恶性肿瘤,其恶性程度高,早期病情隐匿,超过80%的患者在就诊时已进展为晚期,错失手术切除治愈的机会;而成功接受了手术治疗的胰腺癌患者,也极易发生转移,5年生存率仅为15%~20%。不同于其他癌种,胰腺癌的放化疗及免疫治疗效率均较低,分子分型和精准治疗技术的研究也相对落后,急需临床医疗资源的投入和优质科研成果的转化,以改善患者预后。2022年是胰腺癌转化研究领域厚积薄发的一年,见证了第1个靶向KRAS^(G12D)的小分子药物的诞生和个性化T细胞受体工程化T(T-cell receptor engineered T,TCR-T)细胞治疗技术的临床应用,在胰腺癌发病因素、分子机制、代谢、免疫微环境等基础领域,以及早期诊断、手术治疗、药物治疗、免疫治疗等临床领域也各自取得了新突破。本文对2022年胰腺癌研究和诊疗领域的最新进展进行综述。

基于多孔硅纳米线的含能材料的制备及性能调控

纳米多孔硅由于其海绵状的孔隙结构,氧化剂很难充分填充,导致多孔硅复合含能材料多为富燃料体系;同时其孔隙率难以调节,无法精确控制氧燃比。针对以上问题,以紧密排列的单层聚苯乙烯微球为模板,通过反应性离子刻蚀(Reaction Ion Etching,RIE)技术结合金属辅助化学刻蚀(Metal-Assisted Chemical Etching,MACE)制备得到了形貌结构可控的多孔硅纳米线,通过控制RIE时间能够精准调节多孔硅复合体系的氧燃比,同时二维线状结构非常有利于氧化剂的高效填充。结果表明,在RIE时间为80s,即硅纳米线直径为150nm左右时,复合含能体系达到最佳化学计量反应平衡,能量输出最佳。同时,选用不同电阻率的硅片制备得到不同结构形貌的硅纳米线,电阻率越低,纳米复合含能体系中的硅纳米线结构越疏松多孔,不仅能够有效缩短传质传热距离,降低反应活化能,有利于增强反应放热;而且能提升燃烧性能,有利于点火,为硅基含能材料的发展提供了新的思路。

基于TCAD的半导体桥芯片设计与仿真方法

为了提升半导体桥(SCB)芯片设计开发效率,厘清其电击穿作用机制,采用TCAD(Technology Computer Aided Design,计算机辅助设计)工具,开展多晶硅材料掺杂工艺、芯片结构设计以及芯片电击穿过程模拟仿真,探究注入能量与掺杂类型、退火时间与温度等工艺参数,以及强电场条件对载流子分布及性能的影响规律,厘清芯片电击穿的物理机制。仿真结果表明:相比于磷离子注入,砷离子注入能够在更靠近多晶硅层表面的区域,形成更高浓度的载流子分布;快速热退火时间设定为30min,退火温度设定为约600℃,能够有效实现载流子活化;芯片双“V”型尖端电场强度达到3×10^(5)V·cm^(-1)时发生电击穿过程,载流子剧烈碰撞离化,桥区总电流密度最高可达1.16×10^(9)A·cm^(-2)。

Design of novel transition-metal-doped C_(4)N_(4) as highly effective electrocatalysts for nitrogen fixation with a new intrinsic descriptor

Electrocatalytic nitrogen reduction reaction(NRR) is an efficient and green way to produce ammonia,which offers an alternative option to the conventional Haber-Bosch process.Unfortunately,the large-scale industrial application of NRR processes is still hindered by poor Faraday efficiency and high overpotential,which need to be overcome urgently.Herein,combined with density functional theory and particle swarm optimization algorithm for the nitrogen carbide monolayer structural search(C_mN_(8-m),m=1-7),the surprising discovery is that single transition metal-atom-doped C_(4)N_(4) monolayers(TM@C_(4)N_(4)) could effectively accelerate nitrogen reduction reaction.TM@C_(4)N_(4)(TM=29 transition metals) as single-atom catalysts are evaluated via traditional multi-step screening method,and their structures,NRR activity,selectivity and solvation effect are investigated to evaluate their NRR performance,Through the screening steps,W@C_(4)N_(4) possesses the highest activity for NRR with a very low limiting potential of-0.29 V.Moreover,an intrinsic descriptor φ is proposed with machine learning,which shortens the screening process and provides a new idea for finding efficient SACs.This work not only offers promising catalysts W@C_(4)N_(4) for NRR process but also offers a new intrinsic and universal descriptor φ.

品管圈活动下的快速康复管理在子宫肌瘤腹腔镜下全子宫切除术后患者中的应用效果分析

目的:探讨品管圈活动下的快速康复管理在子宫肌瘤腹腔镜下全子宫切除术后患者中的应用效果。方法:选取2021年8月-2022年12月于清远市妇幼保健院行腹腔镜下全子宫切除术的86例子宫肌瘤患者作为研究对象,以随机数字表法分为研究组与对照组,各43例。对照组实行常规围手术期护理模式,研究组实行品管圈活动下的快速康复管理模式。比较两组护理效果。结果:研究组术后肠功能恢复时间、排便时间、进食半流质食物时间、住院时间均短于对照组,焦虑评分、并发症总发生率、疼痛评分低于对照组,健康知识知晓情况、护理满意度评分高于对照组,差异均有统计学意义(P<0.05)。结论:品管圈活动下的快速康复管理在子宫肌瘤腹腔镜下全子宫切除术后评分患者中的应用效果理想,可促进患者术后恢复,缓解患者焦虑情绪,减少并发症,减轻疼痛,提升健康知识知晓率、护理满意度。

CT引导下125I粒子植入术对晚期肺癌及肺转移癌的治疗作用

背景与目的原发性肺癌及肺转移癌均为常见肺部恶性肿瘤,是主要的癌症相关死亡原因。晚期肺癌及肺转移癌以全身治疗为主,局部治疗对全身治疗后肺部残存的顽固性病灶或复发病灶为一种有效治疗手段。125I放射性粒子植入作为一种高效的适形放疗,对肺部局限性癌灶具有一定的控制作用。本研究旨在探讨计算机断层扫描(computed tomography,CT)引导下经皮穿刺肺组织间125 I放射性粒子植入治疗晚期肺癌和肺转移癌的临床效果及安全性。方法连续性收集2014年1月1日-2018年11月30日浙江大学医学院附属第一医院胸外科行125 I放射性粒子植入术治疗的105例晚期肺癌和肺转移癌患者的临床病理资料,术后随访至2019年3月。观察粒子植入术的临床疗效及并发症发生情况。结果本研究共纳入105例患者,晚期肺癌患者78例,肺转移癌患者27例。粒子治疗患者术后中位生存时间为395天,术后1年生存率约为78.1%,术后2年生存率约为56.1%。粒子植入治疗晚期肺癌的效果与肺转移癌的效果相当。粒子联合射频消融、微波消融、化疗并没有提高粒子治疗效果。但是粒子联合外放射治疗较单纯粒子治疗具有显著生存劣势。结论CT引导下125 I放射性粒子植入术并发症可控,可以作为晚期肺癌和肺转移癌的一种安全有效的治疗方法。

The Minimum Centroid Branch Spanning Tree Problem

For a spanning tree T of graph G,the centroid of T is a vertex v for which the largest component of T-v has as few vertices as possible.The number of vertices of this component is called the centroid branch weight of T.The minimum centroid branch spanning tree problem is to find a spanning tree T of G such that the centroid branch weight is minimized.In application to design of communication networks,the loads of all branches leading from the switch center should be as balanced as possible.In this paper,we prove that the problem is strongly NP-hard even for bipartite graphs.Moreover,the problem is shown to be polynomially solvable for split graphs,and exact formulae for special graph familis,say Kn_(1),n_(2),...,n_(k)and P_(m)×P_(n),are presented.

大型体育场馆行人分区疏散优化策略研究

针对大型场所疏散出口通行能力不均衡现象,以某大型体育场馆为对象,建立Pathfinder疏散模型,通过不断改变行人出口选择,得到行人疏散分区优化模型。结果表明:通过对比优化前后疏散时间、疏散过程及疏散出口利用差异,得到疏散时间优化效率10.55%,各出口疏散时间标准差优化效率为90.78%。分区优化能够均衡各出口疏散时间,提高疏散出口利用效率,有效缓解大型场所拥堵问题,为实现大型场所安全疏散提供理论参考。

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空气中的氮气由于其牢固的N≡N三键,不易被植物直接吸收。等离子体固氮为高效实现将氮分子(N_(2))转化为可吸收的含氮化合物(NO_(x),NH_(3)等)提供了新途径。相比传统Haber-Bosch(H-B)工艺,等离子体技术可以使用间歇性可再生能源,成本低廉,并且理论能耗仅为H-B工艺的0.5倍,因而在固氮领域受到广泛关注。本篇综述首先阐述了等离子体在固氮应用上的优势,然后,介绍了等离子体固氮的反应原理以及其在固氮(用于NH_(3)或NO_(x)合成)领域的研究现状,并对比了当前已有的等离子体反应器类型及其固氮效果。最后,总结了等离子体固氮技术当前面临的挑战,并指出了该方向未来研究的重点。