Transmembrane transport characterization across ionic redox transistors using surface-tracked scanning ion conductance microscopy

A fundamental understanding of ion transport at the nanoscale is critical to the development of efficient chemical separation membranes,catalysts,ionic/bio-inspired materials,and its scale up into multi-functional ionic devices.Electrochemical imaging using scanning probe microscopy hardware has provided a method to visualize and understand processes that occur at the surface of ionic active materials.The suite of scanning probe microscopy techniques developed over the last few years are limited to imaging surface-level phenomena and have not been applied to investigate transmembrane properties of synthetic and natural membranes with high spatial and temporal resolution.In this article,we demonstrate the application our recently developed‘surface-tracked scanning ion conductance microscopy’technique to characterize voltage-regulated ion transport in an ionic redox transistor.The ionic redox transistor exhibits controlled transmembrane ion transport as a function of its electrochemical redox state.The technique presented in this article uses shear force measured between the nanopipette and ionic substrate to image topography of the porous substrate and simultaneously characterize topography-correlated transmembrane transport through the ionic redox transistor.The transmembrane conductance measured across an array of pores within the ionic redox transistor varies from 0.004μS/cm(OFF state)to 0.015μS/cm(ON state).We anticipate that the spatial correlation of transmembrane ion transport in the ionic redox transistor would result in a scale up into smart membrane separators for energy storage,neuromorphic circuits,and desalination membranes.

Observation of cavitation and water-refilling processes in plants with X-ray phase contrast microscopy

With the spatial coherence of X-rays and high flux and brightness of the 3rd generation synchrotron radiation facility,X-ray phase contrast microscopy(XPCM)at Shanghai Synchrotron Radiation Facility(SSRF)can provide high resolution dynamic imaging of low electron density materials in principle.In this paper,we investigated the cavitation and water-refilling processes in rice and bamboo leaves utilizing XPCM at SSRF.The occurrence of xylem cavitation was recorded in vivo.The study also revealed that under different dehydration conditions,cavitation occurs in different degrees,and therefore,the refilling process is different.The results demonstrate that SSRF can provide high enough fluxes to study dynamic processes in plants in real-time,and XPCM is expected to be a promising method to reveal the mechanisms of cavitation and its repair in plants nondestructively.

Hybrid brightfield and darkfield transport of intensity approach for high-throughput quantitative phase microscopy

Transport of intensity equation(TIE)is a well-established non-interferometric phase retrieval approach that enables quantitative phase imaging(QPI)by simply measuring intensity images at multiple axially displaced planes.The advantage of a TIE-based QPI system is its compatibility with partially coherent illumination,which provides speckle-free imaging with resolution beyond the coherent diffraction limit.However,TIE is generally implemented with a brightfield(BF)configuration,and the maximum achievable imaging resolution is still limited to the incoherent diffraction limit(twice the coherent diffraction limit).It is desirable that TIE-related approaches can surpass this limit and achieve high-throughput[high-resolution and wide field of view(FOV)]QPI.We propose a hybrid BF and darkfield transport of intensity(HBDTI)approach for highthroughput quantitative phase microscopy.Two through-focus intensity stacks corresponding to BF and darkfield illuminations are acquired through a low-numerical-aperture(NA)objective lens.The high-resolution and large-FOV complex amplitude(both quantitative absorption and phase distributions)can then be synthesized based on an iterative phase retrieval algorithm taking the coherence model decomposition into account.The effectiveness of the proposed method is experimentally verified by the retrieval of the USAF resolution target and different types of biological cells.The experimental results demonstrate that the half-width imaging resolution can be improved from 1230 nm to 488 nm with 2.5×expansion across a 4×FOV of 7.19 mm2,corresponding to a 6.25×increase in space-bandwidth product from∼5 to∼30.2 megapixels.In contrast to conventional TIE-based QPI methods where only BF illumination is used,the synthetic aperture process of HBDTI further incorporates darkfield illuminations to expand the accessible object frequency,thereby significantly extending the maximum available resolution from 2NA to∼5NA with a∼5×promotion of the coherent diffraction limit.Given its capability for high-throughput QPI,the proposed HBDTI approach is expected to be adopted in biomedical fields,such as personalized genomics and cancer diagnostics.

Distribution, Transportation and Cytolocalization of Neodymium in Oilseed Rape (Brassica napus L.)

Observation xith the transmission electronic microscopy shows that Nd can not enter into the cytoplasm of oilseed rape (brassica napus L.) in solution culture. It combines with the cell wall or amasses in the intercellular space. Nd accumulates in root tip after it enters into the plants, while only a small amount of Nd is transferred to the stem and leaf via apoplasm, and the leaf contains the least of Nd. Such observations are consistent with the analytical results of Nd distribution in rape tissues in soil culture experiment. It suggests that the physiological effects of Nd in plants might mainly function on plasmalemma of root system.

Kelvin probe force microscopy for perovskite solar cells

Kelvin probe force microscopy(KPFM) could identify the local work function of surface at nanoscale with high-resolution on the basis of simultaneous visualization of surface topography, which provides a unique route to in-situ study of the surface information like the composition and electronic states. Currently, as a non-destructive detection protocol, KPFM demonstrates the unique potential to probe the basic nature of perovskite materials that is extremely sensitive to water, oxygen and electron beam irradiation. This paper systematically introduces the fundamentals and working mode of KPFM, and elaborates the promising applications in perovskite solar cells for energy band structures and carrier transport dynamics, trap states, crystal phases, as well as ion migration explorations. The comprehensive understanding of such potential detection engineering may provide novel and effective approaches for unraveling the unique properties of perovskite solar cells.

Er intercalation and its impact on transport properties of epitaxial graphene

Intercalation of atomic species is a practicable method for epitaxial graphene to adjust the electronic band structure and to tune the coupling between graphene and Si C substrate. In this work, atomically flat epitaxial graphene is prepared on 4H-SiC(0001) using the flash heating method in an ultrahigh vacuum system. Scanning tunneling microscopy, Raman spectroscopy and electrical transport measurements are utilized to investigate surface morphological structures and transport properties of pristine and Er-intercalated epitaxial graphene. It is found that Er atoms are intercalated underneath the graphene layer after annealing at 900℃, and the intercalation sites of Er atoms are located mainly at the bufferlayer/monolayer-graphene interface in monolayer domains. We also report the different behaviors of Er intercalation in monolayer and bilayer regions, and the experimental results show that the diffusion barrier for Er intercalated atoms in the buffer-layer/monolayer interface is at least 0.2 eV higher than that in the first/second graphene-layer interface. The appearance of Er atoms is found to have distinct impacts on the electronic transports of epitaxial graphene on SiC(0001).

基于相位恢复的透明样本3维重建系统

为解决传统显微成像技术难以获取无色透明样本结构和厚度的问题,设计了一款小型透明样本3维重建系统。该系统通过对透明样本进行相位恢复,实现3维重建。系统的设计突破了传统光学结构,只需输入携带样本信息的光线,经过分光棱镜分成两路,终由双目相机捕获。系统使用3D打印制作,尺寸仅为110 mm×110 mm×60 mm,成本低廉,并可与传统显微成像设备配合使用。系统内置自动对焦和视场配准算法,只需采集1张过焦和1张欠焦图像,通过求解光强传输方程便可进行相位恢复,从而实现透明样本的3维重建。测试结果显示,10倍物镜下系统的成像分辨率可达2.46μm,同时相位恢复精确度也能达到基本要求。系统成功对血细胞和载玻片划痕进行了3维重建,证明了系统的可行性与实用性。

木质素单体跨膜转运的技术研究进展

木质素(lignin)作为一种重要的可再生资源,主要集中在植物的次生细胞壁中,在植物的营养物质运输、机械支持和病原体防御等生理过程中发挥着关键作用。木质素的形成过程包括3个主要环节:单体的胞内合成、跨膜转运以及胞外聚合。深入探究木质素单体跨膜转运的分子机制,对揭示细胞壁形成分子机制及木材改良具有重要意义。基于此,本综述从转录组学、基因工程、点击化学、荧光显微成像、分子模拟等技术角度,对木质素单体跨膜转运的相关进展和最新技术进行了梳理和总结,阐述了木质素单体跨膜转运相关研究的新技术和存在的技术瓶颈,并对比分析了不同技术之间的优缺点,最后提出了木质素单体跨膜转运机制研究中仍存在的问题和面临的挑战。相信随着成像技术、结构生物学、人工智能等科技的飞速发展,将为进一步阐明木质素单体跨膜转运的分子机理提供有效的技术手段。期望本综述为木质素单体的相关研究提供新的思路和方法。

What we know about axons in Parkinson’s disease

Tremendous research efforts have been made regarding the pathogenesis of Parkinson’s disease(PD).However,there are still no effective strategies to restore midbrain dopaminergic(mDA)innervation and prevent disease progression.One possibility is that we may have been neglecting the role of axons in mDA neuronal degeneration.This review first summarizes mDA axon development during the early stage of PD and discusses how axon guidance defects contribute to PD vulnerability.Furthermore,we review axonal transport dysregulation in the numerous PD-related genetic mutations,including Parkin,PINK1,DJ1,LRRK2 and SNCA.The evidence suggests that proper axonal transport is crucial for neuronal function and survival.Finally,advanced tools for axonal studies were evaluated,including light-sheet and super-resolution microscopy.These adapted microscopes have been used to help solve questions unanswered before.Overall,the role of axon terminals in the initiation of the degeneration cascade remains undeciphered,and more research in the related area may be conducted further to restore dopamine levels in the striatum to alleviate the motor complications of PD.

与蚕豆萎蔫病毒2号胞间运动和长距离转运相关的寄主细胞超微结构研究

电镜超微结构观察和免疫金标记显示:受蚕豆萎蔫病毒2号(Broad bean wilt virus 2,BBWV 2)中国分离物B935侵染的豌豆(Pisum sativum)和蚕豆(Vicia faba)叶细胞中膜结构增生,形成膜结构增生区,病毒以结晶体和管状体形式存在于细胞质中。在病变早期,叶肉细胞的胞间连丝处连接有小管结构,病毒样颗粒呈纵列排在小管中,穿越胞间连丝的小管能被BBWV 2的金标记抗体特异性标记。维管束组织的薄壁细胞、伴胞及转移细胞内存在膜增生区及病毒管状体,在筛管壁附近存在的病毒样颗粒能被BBWV 2金标记抗体特异性标记。实验结果表明BBWV 2胞间运动形式与豇豆花叶病毒(CPMV)相似,以完整粒子通过在胞间连丝处形成的小管结构穿越胞间连丝;细胞质中存在的直径160nm管状体只是一种病毒聚集体,与胞间运动无直接关系;该病毒在筛管中可能也是以完整粒子形式进行长距离转运的。

元素迁移的模拟模型实验

从野外不同地质体上 ,观察到地壳中元素是以纳米微粒状态被上升气流迁移的。为了进一步研究 ,设计了模拟上升气流通过矿层、矿层加盖层及围岩的模型层。实验结果显示 ,在模型中上升气流迁移的粒子仍是纳米微粒 ,并且采样片上含量也是随时间积累而增加。当有水层和玻璃盖层时 ,部分元素仍能穿透盖层 ,部分元素迁移受阻挠。纯扩散实验说明纯扩散迁移也存在 ,不过迁移量很小。列出模型实验中用扫描探针显微术观察到的纳米微粒照片。

大鼠原代脂肪细胞中单个GLUT4囊泡的成像——全内反射荧光显微成像技术的应用

本研究采用高斯拟合算法与全内反射荧光显微技术(TIRFM),通过实时动态的单粒子追踪拍摄来分析原代培养大鼠脂肪细胞基础条件及胰岛素刺激下细胞膜附近绿色荧光蛋白(GFP)标记的GLUT4囊泡的运动变化.使用高斯拟合来消除光学成像系统中发生的原始样品中单像素点荧光强度值的污染,重建出囊泡真实的中心点荧光强度值.通过对序列图像中的囊泡点应用高斯拟合和相应的搜索算法,得到所有囊泡的高斯中心点荧光强度值序列,继而描绘出囊泡的动态转运路径.结果表明,基础条件下膜附近的多数GLUT4囊泡处于沿同一路径的快速长距离转运状态;胰岛素刺激后,长距离转运的GLUT4囊泡数量减少,多数GLUT4囊泡固定成团或者在原地摆动呈限制性的运动.当GLUT4囊泡锚定至膜上后,即迅速与膜融合.说明高斯拟合算法及全内反射荧光显微技术的结合可以很好地实现囊泡纳米尺度的三维实时追踪.

热缺血损伤对大鼠心脏死亡供肝线粒体形态和功能的影响

背景:如何才能很好的把握控制心脏死亡后捐献器官的功能活性,使移植物达到最佳功能状态是器官移植领域研究的重点方向之一。目的:初步探讨热缺血损伤对大鼠心脏死亡供肝功能的影响。方法:建立SD大鼠心脏死亡动物模型,将大鼠随机分为6组,分别为对照组(热缺血0 min组),热缺血10 min组,热缺血20 min组,热缺血30 min组,热缺血40 min组和热缺血50 min组。取各组大鼠肝脏标本制备超薄切片,透射电镜观察肝细胞结构改变并行Flameng评分。提取肝脏线粒体,用分光光度法测定细胞色素C氧化酶的活性。结果与结论:透射电镜下见热缺血30 min内肝细胞无明显改变,核膜尚完整,线粒体轻度肿胀,线粒体嵴未发生断裂,Flameng评分在2分以下。随着热缺血时间的延长,细胞核固缩,部分肝细胞自溶,可见凋亡小体,线粒体基质凝固,线粒体逐渐呈空泡状,Flameng评分3至4分。线粒体细胞色素C氧化酶活性在热缺血30 min内无明显改变,热缺血40 min组和热缺血50 min组发生明显降低。从线粒体形态和细胞色素C氧化酶活性两方面来看,热缺血时间在30 min内对肝脏功能影响较小,热缺血时间在40 min以上时肝脏呈不可逆性损伤。

ESR和CLSM技术用于促渗剂作用机制及亲水性大分子跨鼻黏膜转运途径的研究

采用电子自旋共振(ESR)和共聚焦激光扫描显微镜(CLSM)技术研究促渗剂作用机制及促渗剂对亲水性大分子跨鼻黏膜转运途径的影响。比较重组水蛭素-2(rHV2)与促渗剂联合鼻腔用药前后大鼠的生物利用度;采用以5-噁唑烷氮氧自由基硬脂酸、16-噁唑烷氮氧自由基硬脂酸和马来酰亚胺作为自旋标记物的电子自旋共振技术,考察促渗剂对家兔鼻黏膜脂质和蛋白的影响;采用共聚焦显微镜光学切片结合荧光探针标记技术探讨促渗剂对大鼠鼻黏膜上皮细胞骨架肌动蛋白的作用,同时观察在各种促渗剂作用下rHV2的转运途径。壳聚糖(chitosan,CS),羟丙基-β-环糊精(hydroxyl-propyl-beta-cyclodextrin,HP-β-CD),甘草酸单胺盐(ammonium glycyrrhizinate,AMGZ)均能显著改善rHV2的鼻黏膜吸收;CS主要通过细胞旁路途径增加rHV2鼻黏膜转运,这一结果可能与其对细胞骨架肌动蛋白微丝的影响从而打开细胞间紧密连接有关;HP-β-CD可同时增加跨细胞和经细胞旁路两种途径的转运,可能与其既能改变膜质流动性又能影响膜蛋白构象的特性有关;AMGZ主要增加亲水性大分子跨细胞途径的转运,实验观察到其对膜蛋白有作用,但未观察到其对膜质的作用,确切的机制尚有待研究。本实验可为促渗剂及亲水大分子跨细胞膜转运途径的研究提供借鉴。

加速器联机装置运行状况

2008年武汉大学加速器联机系统初步建成,200 kV离子注入机至透射电镜束线进行了运行调试,开展了气体离子注入单晶Si、GaAs、Ag纳米晶和超临界反应堆材料(C276和6XN)的原位结构研究。结果表明,样品在注入至一定剂量时发生明显多晶和非晶化,单晶Si出现非晶化的临界剂量在10^(14) cm^(-2)。C276材料经1×10^(15)cm^(-2)的Ar离子辐照后,产生尺寸3-12 nm的位错环,其密度随剂量提高而增大,至5×10^(15)cm^(-2)出现多晶,剂量超过3×10^(16) cm^(-2)出现非晶化。在加速器-电镜联机光路上安装在线RBS靶室对离子束辐照材料进行元素成分和晶格定位测试。靠近电镜端安装50 kV低能离子源,开展核材料中氦泡形成过程的原位观测。对RBS/C装置进行数字化改造,用Labview控制系统运行,目前可进行计算机控制的背散射沟道测试。

InAs量子点引入应力对调制掺杂结构中二维电子气输运特性的影响(英文)

系统研究了在调制掺杂AlGaAs/GaAs异质结中嵌入InAs量子点后对二维电子气输运特性的影响。使用分子束外延设备生长了量子点层与二维电子气沟道距离(Tch)不同的3个样品,霍尔测试结果表明,二维电子气的电子迁移率和载流子浓度都随Tch的减小而降低。基于几何相位分析算法对部分样品的高分辨透射电镜图像进行了处理,得到了其应变分布图。结果表明,应变主要分布在量子点的周围,并延伸到了量子点的上方。该不均匀的应力场可能是除库伦散射外影响电子迁移率降低的另一个重要因素。

腹膜表面超微结构的观察

目的 证实大鼠腹膜表面液体层的存在并探讨其可能组成成分。 方法 取正常大鼠腹膜组织 ,分别以不同固定液固定 :(1) 2 .5 %戊二醛和 2 %多聚甲醛 (对照组 ) ;(2 ) 2 .5 %戊二醛和 0 .5 %氯化十六烷基吡啶 (GAG组 ) ;(3) 2 % Os O4(PH 1组 ) ;(4 ) 4 % Os O4(PH2组 ) ;(5 ) 3%鞣酸 (鞣酸组 )。 结果 对照组中可见腹膜间皮细胞表面的微绒毛 ,未见表面液体层。GAG组腹膜表面可见一层不连续的无定形结构。此层结构在 PH1和 PH 2组中保存较好 ,厚度达到 10μm。鞣酸组表面液体层及间皮细胞中可见许多类板层小体。 结论 研究证实 :正常大鼠腹膜表面覆盖着一层膜样结构 ,它至少由磷脂和葡糖胺聚糖组成。该层在腹膜物质转运中可能有重要的屏障作用。

小鼠脊髓内存在抑制性含锌神经元

目的探讨小鼠脊髓中是否含有抑制性的含锌神经元。方法应用锌金属自显影技术、免疫电镜技术和共聚焦激光扫描显微术,研究游离锌离子、锌转运蛋白(zinc transporter 3,ZnT3)与(glutamic acid decarboxylate,GAD)在小鼠脊髓内的共存情况。结果小鼠脊髓内至少有三种含锌神经元轴突终末,其中大多数为GAD阳性即γ-氨基丁酸能含锌神经元轴突终末,另外两种分别为GAD阴性含扁圆形小泡的甘氨酸能含锌神经元轴突终末和含圆形清亮小泡的兴奋性谷氨酸能含锌神经元轴突终末。结论在哺乳动物脊髓内存在大量的抑制性含锌神经元。锌离子从抑制性含锌神经元轴突终末释放到突触间隙内,作为神经调质作用于突触后的GABA受体或甘氨酸受体,参与脊髓运动和感觉功能的调控。

肝癌抑制基因-1与转运功能相关的451bp序列区的确定

背景与目的:肝癌抑制基因-1(HCCS1)是一种潜在的肝癌抑制基因,并且在细胞内蛋白分拣运输中也发挥着重要作用,其抑癌作用有可能是通过其蛋白转运的功能而发挥的,本文以寻找HCCS1序列中与转运相关的最小功能序列区域为目的。方法:通过亚克隆技术,构建以pEGFP-C2为载体的含不同长度HCCS1cDNA片段的亚克隆,将构建的亚克隆转染子宫颈癌HeLa细胞,通过免疫荧光共聚焦显微镜观察不同长度HCCS1蛋白的分布,以及与6-磷酸甘露糖受体(M6PR)的共定位。结果:成功构建了以pEGFP-C2为载体的10个含有不同长度HCCS1片段的亚克隆;HCCS1cDNA从3'端向5'端逐渐缺失的片段中:2100bp片段至778bp片段编码的不同长度HCCS1蛋白呈颗粒状分布于核周的胞质内,其中2100bp片段至1571bp片段编码的不同长度HCCS1蛋白均呈颗粒状、极性分布于核周的胞质内,且与M6PR有共定位;而1120bp片段至778bp片段编码的不同长度HCCS1蛋白虽然也呈颗粒状分布于核周,但极性分布消失,且与M6PR共定位消失;HCCS1cDNA片段678bp片段至339bp片段编码的不同长度HCCS1蛋白呈散点状弥散分布于胞质以及胞核内。结论:确定了HCCS1cDNA1571bp片段的3'端451bp的序列为与HCCS1转运功能相关的最小区域范围。

全固态电池中界面的结构演化和物质输运

全固态电池中科学问题的本质在于引入的固态电解质的特性及全新的固-固界面的存在.从构-效关系出发,固-固界面和电解质自身的结构演化与物质输运过程决定了全固态电池的性能.随着固态电解质材料研究的不断丰富,目前全固态电池中的问题主要集中在固-固界面,界面处的组成和结构限制了全固态电池的性能.根据固-固界面接触的情况不同,本文按照固-固界面物理接触、化学接触和表面改性处理这三个层次总结与讨论全固态电池中固-固界面处的结构及其物质输运.最后从功能材料功能性起源角度讨论局域对称性与宏观复杂体系下材料性能的关联.