nanotube

纳米管
  • 文章类型: Journal Article
    糖尿病伤口的愈合长期以来一直是医学领域的重大挑战。糖尿病伤口周围的糖水平升高为有害细菌生长创造了有利的环境,导致化脓性感染,阻碍愈合过程。因此,开发可增强糖尿病伤口愈合的生物材料非常重要。本研究通过结合中药和粘土开发了用于伤口愈合的电纺敷料。该研究利用静电纺丝技术制备了含ASB和HNTs的聚乙烯醇(PVA)纳米纤维膜。这些ASB@HNTs-PVA纳米纤维膜表现出快速止血,以及抗菌和抗炎特性,促进2型糖尿病(T2D)伤口的恢复。进行了各种分析以评估复合纳米纤维膜的性能,包括通过抗菌实验研究其生物相容性和止血能力,细胞实验,和小鼠肝尾出血实验。Westernblot分析证实复合纳米纤维膜可降低炎症因子IL-1β和TNF-α的水平。利用2型糖尿病小鼠模型,老鼠背上人工诱导的伤口。将纳米纤维膜应用于伤口进一步证实了其抗炎作用和增强体内伤口愈合的能力。
    The healing of diabetic wounds has long been a significant challenge in the field of medicine. The elevated sugar levels surrounding diabetic wounds create a conducive environment for harmful bacterial growth, resulting in purulent infections that impede the healing process. Thus, the development of a biomaterial that can enhance the healing of diabetic wounds holds great importance. This study developed electrospun dressings for wound healing by combining traditional Chinese medicine and clay. The study utilized electrospinning technology to prepare polyvinyl alcohol (PVA) nanofiber membranes containing ASB and HNTs. These ASB@HNTs-PVA nanofiber membranes demonstrated rapid hemostasis, along with antibacterial and anti-inflammatory properties, facilitating the recovery of type 2 diabetic (T2D) wounds. Various analyses were conducted to assess the performance of the composite nanofiber membrane, including investigations into its biocompatibility and hemostatic abilities through antibacterial experiments, cell experiments, and mouse liver tail bleeding experiments. Western blot analysis confirmed that the composite nanofiber membrane could decrease the levels of inflammatory factors IL-1β and TNF-α. A type 2 diabetic mouse model was utilized, with wounds artificially induced on the backs of mice. Application of the nanofiber membrane to the wounds further confirmed its anti-inflammatory effects and ability to enhance wound healing in vivo.
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  • 文章类型: Journal Article
    超原子簇-各种大小的原子的集合,形状,和成分-可以形成层次结构,这些体系结构表现出在其各个单元中没有发现的紧急电子特性。特别是,硫属化物的立方M4X4团簇(M=过渡金属;X=硫属)被认为是具有可调形态和电子性质的3D结构的通用结构单元。然而,四面体M4X4集群很少组装成2D架构,可以从他们的3D类似物中提供不同类型的功能材料。这里,这项工作报告了2DMo8S8Cl11的制备,这是一种超原子层,具有三明治结构,由通过Cl交联互连的Mo4S4簇组成。纳米管内部的气相反应促进了Mo8S8Cl11纳米带的选择性生长,允许通过透射电子显微镜详细表征。该方法可以应用于微米级的含有Mo8S8Cl11的层状结构的生长。这项工作表明,单层和少层Mo8S8Cl11可以通过剥离母体固体来制备。电子结构计算表明2D单层具有准平坦带,在机械应变下产生间接到直接的带隙跃迁。此外,扫描电化学显微镜揭示了层状结构作为析氢反应的高效催化剂的潜力。
    Superatomic clusters - assemblies of atoms with various sizes, shapes, and compositions - can form hierarchical architectures that exhibit emergent electronic properties not found in their individual units. In particular, cubic M4X4 clusters of chalcogenides (M = transition metal; X = chalcogen) are recognized as versatile building blocks for 3D structures with tunable morphologies and electronic properties. However, tetrahedral M4X4 clusters rarely assemble into 2D architectures, which could offer a distinct class of functional materials from their 3D analogues. Here, this work reports the preparation of 2D Mo8S8Cl11, a superatomic layer with a sandwich structure consisting of Mo4S4 clusters interconnected through Cl cross-linking. The vapor-phase reaction inside nanotubes promotes the selective growth of Mo8S8Cl11 nanoribbons, allowing detailed characterization via transmission electron microscopy. This methodology can be applied to the growth of layered structures containing Mo8S8Cl11 at the micrometer scale. This work has demonstrated that mono- and few-layer Mo8S8Cl11 can be prepared by exfoliation of parent solids. Electronic structure calculations indicate that the 2D monolayer has quasi-flat bands, giving rise to an indirect-to-direct bandgap transition under mechanical strain. Furthermore, scanning electrochemical microscopy reveals the potential of the layered structures as highly efficient catalysts for the hydrogen-evolution reaction.
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  • 文章类型: Journal Article
    碳是现有和新兴能源应用的关键材料,在产生可持续碳方面有相当大的全球努力。一个特别有前途的领域是铁催化的石墨化,这是通过铁催化剂将有机物转化为石墨碳纳米结构。在本文中,据报道,铁催化的石墨化是通过一种称为均相固态催化的新型机理发生的。暗场原位透射电子显微镜用于证明晶体铁纳米颗粒“钻洞”通过无定形碳产生多壁石墨纳米管。这个过程非常快,特别是考虑到催化剂的固相,原位同步加速器X射线衍射用于证明石墨化在几分钟内完成。
    Carbon is a critical material for existing and emerging energy applications and there is considerable global effort in generating sustainable carbons. A particularly promising area is iron-catalyzed graphitization, which is the conversion of organic matter to graphitic carbon nanostructures by an iron catalyst. In this paper, it is reported that iron-catalyzed graphitization occurs via a new type of mechanism that is called homogeneous solid-state catalysis. Dark field in situ transmission electron microscopy is used to demonstrate that crystalline iron nanoparticles \"burrow\" through amorphous carbon to generate multiwalled graphitic nanotubes. The process is remarkably fast, particularly given the solid phase of the catalyst, and in situ synchrotron X-ray diffraction is used to demonstrate that graphitization is complete within a few minutes.
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  • 文章类型: Journal Article
    这项研究探讨了具有碳纳米管(CNT)线性X射线源阵列的固定式机架心脏门控计算机断层扫描(CT)的可行性。传统的旋转CT受到快速旋转的机架上的旋转力的限制。我们最近开发了一种利用多像素CNTX射线源的固定式机架CT系统。由于这些源还可以实现直接的X射线脉冲控制,我们试图探索使用我们的固定CT系统进行门控前瞻性成像的潜力.实施了前瞻性呼吸和心脏门控控制,并通过动态体模成像研究对系统进行了评估,然后对猪模型进行了心脏和呼吸门控成像。研究结果揭示了最小的运动伪影,在固定的龙门心脏CT中确认成功的生理门控采集,显示了这种成像方法的潜力。 .
    Objective.This study explores the feasibility of a stationary gantry cardiac gated computed tomography (CT) with carbon nanotube (CNT) linear x-ray source arrays.Approach.We developed a stationary gantry CT system utilizing multipixel CNT x-ray sources. Given the advantages of straightforward x-ray pulse control with these sources, we investigated the potential for gated prospective imaging. We implemented prospective respiratory and cardiac gating control and evaluated the system through dynamic phantom imaging studies followed by imaging of a porcine model.Main Results.The findings revealed minimal anatomical motion artifacts in the heart and lungs, confirming successful physiologic gated acquisition in stationary gantry cardiac CT. This indicates the potential of this imaging approach for reducing artifacts and improving image quality.Significance.This study demonstrates the feasibility of prospective physiological gating with CNT x-ray sources in a stationary gantry setup for cardiac imaging. This approach could potentially alleviate the need for beta blocker administration during cardiac CT scans, thereby increasing the flexibility of the imaging system and enabling the imaging of a wider variety of patient cardiac conditions.
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  • 文章类型: Journal Article
    由4-氰基-N-(4-氰基苄基)吡啶鎓组装的两个离子氢键有机骨架(iHOF),已经用溴和五溴化锑(III)结晶,[SbBr5]2-,作为抗衡离子和特征。这些是4-氰基-N-(4-氰基苄基)溴化吡啶,C14H10N3+·Br-,和双[4-氰基-N-(4-氰基苄基)吡啶]锑(III)五溴铵,(C14H10N3)2[SbBr5]。CH。..模板阴离子诱导的NC相互作用构建了不同的框架。Hirshfeld表面分析表明,这些晶体表现出两种类型的氢键相互作用,特别是CH。..NC和CH。..Br.连续反向并联CH。..这些晶体中的NC氢键相互作用诱导了大量CH的形成。..表现出顺式和反式构型的NC键。
    Two ionic hydrogen-bonded organic frameworks (iHOFs) assembled from 4-cyano-N-(4-cyanobenzyl)pyridinium, have been crystallized with Br- and antimony(III) pentabromide, [SbBr5]2-, as counter-ions and characterized. These are 4-cyano-N-(4-cyanobenzyl)pyridinium bromide, C14H10N3+·Br-, and bis[4-cyano-N-(4-cyanobenzyl)pyridinium] antimony(III) pentabromide, (C14H10N3)2[SbBr5]. The CH...NC interactions induced by templating anions construct disparate frameworks. Hirshfeld surface analysis indicated that these crystals exhibit two types of hydrogen-bonding interactions, specifically CH...NC and CH...Br. Consecutive reverse-parallel CH...NC hydrogen-bonding interactions in these crystals induced the formation of a large number of CH...NC bonds which exhibit both cis and trans configurations.
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  • 文章类型: Journal Article
    纳米管和纳米线晶体管由于其缩小尺寸的可能性而对未来的电子和光电器件具有很大的希望。在这项工作中,单个多壁二硫化钨(WS2)纳米管用作背栅极场效应晶体管的沟道。该器件在环境条件下表现出p型行为,空穴迁移率µp≈1.4cm2V-1s-1,亚阈值摆动SS≈10Vdec-1。在不同温度下的电流-电压表征表明,该器件在漏极和源极触点处呈现两种略有不同的非对称肖特基势垒。证明了由光伏效应驱动的自供电光电导,在2V漏极偏压和室温下,光响应度R≈10mAW-1。此外,对晶体管进行数据存储应用测试。报告了一个双态存储器,其中正和负栅极脉冲驱动两个不同电流状态之间的切换,由130%的窗口隔开。最后,门脉冲和光脉冲组合以演示具有四个良好分离状态的光电存储器。本文提供的结果对数据存储很有希望,布尔逻辑,和神经网络应用。
    Nanotube and nanowire transistors hold great promises for future electronic and optoelectronic devices owing to their downscaling possibilities. In this work, a single multi-walled tungsten disulfide (WS2) nanotube is utilized as the channel of a back-gated field-effect transistor. The device exhibits a p-type behavior in ambient conditions, with a hole mobility µp ≈  1.4 cm2V-1s-1 and a subthreshold swing SS ≈ 10 V dec-1. Current-voltage characterization at different temperatures reveals that the device presents two slightly different asymmetric Schottky barriers at drain and source contacts. Self-powered photoconduction driven by the photovoltaic effect is demonstrated, and a photoresponsivity R ≈ 10 mAW-1 at 2 V drain bias and room temperature. Moreover, the transistor is tested for data storage applications. A two-state memory is reported, where positive and negative gate pulses drive the switching between two different current states, separated by a window of 130%. Finally, gate and light pulses are combined to demonstrate an optoelectronic memory with four well-separated states. The results herein presented are promising for data storage, Boolean logic, and neural network applications.
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  • 文章类型: Journal Article
    具有可控几何形状的DNA纳米管具有广泛的跨学科应用。当制备不同宽度或不同手性的DNA纳米管时,现有的方法需要反复设计和合成特定的DNA序列,这可能是昂贵和费力的。这里,我们提出了一种嵌入剂辅助的DNA瓦片组装方法,该方法可以使用相同的DNA链生产不同宽度和手性的DNA纳米管。通过在组装过程中调节嵌入剂的浓度,可以调节DNA瓦片的扭曲方向和程度,导致形成具有可控宽度和手性的DNA纳米管。此外,通过引入额外的嵌入剂和二次退火,右旋纳米管可以重新配置成不同的左旋纳米管。我们期望这种方法可以普遍应用于调节各种DNA瓦片和其他手性材料的自组装途径,推进DNA瓷砖组装的景观。
    DNA nanotubes with controllable geometries hold a wide range of interdisciplinary applications. When preparing DNA nanotubes of varying widths or distinct chirality, existing methods require repeatedly designing and synthesizing specific DNA sequences, which can be costly and laborious. Here, we proposed an intercalator-assisted DNA tile assembly method which enables the production of DNA nanotubes of diverse widths and chirality using identical DNA strands. Through adjusting the concentration of intercalators during assembly, the twisting direction and extent of DNA tiles could be modulated, leading to the formation of DNA nanotubes featuring controllable widths and chirality. Moreover, through introducing additional intercalators and secondary annealing, right-handed nanotubes could be reconfigured into distinct left-handed nanotubes. We expect that this method could be universally applied to modulating the self-assembly pathways of various DNA tiles and other chiral materials, advancing the landscape of DNA tile assembly.
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  • 文章类型: Journal Article
    受最近关于penta-MgN8板材的报告的激励[Mater。今天Phys.2023,38,101259]这是首次实现5型五边形2D镶嵌,其中暴露了规则分布的Mg离子,我们进行了密度泛函理论研究H2分子与一维五纳米管的相互作用,2Dpenta-sheet,和基于penta-MgN8的3D多孔结构。我们发现,当penta-MgN8薄片组装成3D多孔结构或弯曲成纳米管时,带隙从1.18增加到1.35和1.88eV,并且得到的导数是动态稳定的。当引入H2分子时,纳米管在吸附方面表现最好,其中每个Mg离子可以吸附三个H2分子:两个在外表面上,一个在内表面上。与2D薄片和3D多孔结构的情况相比,纳米管的弯曲几何形状使外表面上的Mg离子更暴露。导致对H2的更强吸附。对于所研究的五片和五纳米管,重量容量(体积容量)为4.25wt%(63g/L)和4.25wt%(65g/L),在1个大气压下,相应的解吸温度为115和162K,分别,而对于3D多孔结构,由于有限的空间和较小的曲率,吸附性能较差,导致强烈的空间位阻和较少的镁离子暴露配置。此外,还讨论了温度和压力对吸附的影响。
    Motivated by the recent report on penta-MgN8 sheet [Mater. Today Phys. 2023, 38, 101259] that is the first realization of type-5 pentagonal 2D tessellation with exposed regularly distributed Mg ions, we carried out density functional theory studies on the interactions of H2 molecules with 1D penta-nanotube, 2D penta-sheet, and 3D porous structures based on penta-MgN8. We found that when the penta-MgN8 sheet is assembled to a 3D porous structure or curved to a nanotube, the bandgap increases from 1.18 to 1.35 and 1.88 eV, and the resulting derivatives are stable dynamically. When H2 molecules are introduced, the nanotube behaves best in adsorption, where each Mg ion can adsorb three H2 molecules: two on the outer surface and one on the inner surface. The curved geometry of the nanotube makes the Mg ion on the outer surface more exposed as compared with the situations of the 2D sheet and 3D porous structure, resulting in stronger adsorptions to H2. The gravimetric capacity (volumetric capacity) is 4.25 wt % (63 g/L) and 4.25 wt % (65 g/L) for the studied penta-sheet and penta-nanotube, and the corresponding desorption temperature is 115 and 162 K at 1 atm pressure, respectively, while for the 3D porous structure, the adsorption performance is poor due to the limited space and the less curvature, leading to strong steric hindrance and less exposed configuration for Mg ions. Moreover, the effects of temperature and pressure on adsorption are also discussed.
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  • 文章类型: Journal Article
    毛细管金属管已经引起了人们对柔性电子设备的极大兴趣,便携式设备,痕量采样,和检测。定制毛细管内部的微观结构和润湿性是最重要的,然而,由于空间限制,它提出了很大的困难。这里,在阳极氧化过程中,气泡在有限空间中运动引起的流体和电场之间表现出耦合效应。通过控制气泡再生和流速,在直径为0.4mm,长度为1000mm的超细Ti管的整个内表面形成均匀和超亲水的TiO2纳米管阵列,相当于2500的纵横比,这是有史以来报告的最大值。毛细管的内表面进一步涂覆有聚四氟乙烯层,并且探索作为用于在浓度和种类方面进行液体检测的感测针。这项研究提供了一种创新的方法来定制功能毛细管在密闭空间中的微观结构和润湿性。
    Capillary metal tubes have attracted considerable interest for flexible electronics, portable devices, trace sampling, and detection. Tailoring the microstructure and wettability inside the capillary tubes is of paramount importance, yet it presents great difficulty because of the spatial confinement. Here, the coupling effect is revealed between the fluidic and electric field induced by bubble motion in a confined space during anodic oxidation. By controlling the bubble regeneration and flow rate, uniform and superhydrophilic TiO2 nanotube arrays are developed throughout the inner surface of an ultrafine Ti tube with a diameter of 0.4 mm and length of 1000 mm, equivalent to an aspect ratio of 2500 that is the largest value being ever reported. The inner surface of a capillary tube is further coated with a polytetrafluoroethylene layer and explored as a sensing needle for liquid detection in terms of concentration and species. This study provides an innovative approach to tailor the microstructure and wettability in a confined space for functional capillary tubes.
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  • 文章类型: Journal Article
    纳米管由于其原子上薄的几何形状和有趣的特性而在纳米科学中建立了新的范例。然而,因为它们与2D和3D对应物相比具有典型的亚稳态,合成具有可控尺寸的纳米管仍然具有根本性的挑战性。已经提出了用于合成具有受控几何形状的纳米管的新策略。其中之一是考虑Janus2D图层,可以自行滚动形成纳米管。在这里,我们使用密度泛函理论(DFT)计算基于36个JanusIV-VI化合物研究了412个纳米管(沿扶手椅和锯齿形方向)。通过使用结构模型和贝叶斯预测研究能量-半径关系,最稳定的纳米管表现出负应变能和半径低于20Λ,其中曲率效应可以发挥重要作用。能带结构表明,所选择的纳米管表现出相当大的带隙和尺寸依赖性电子特性。更引人注目的是,这些纳米管中沿平面内方向和径向方向的挠曲电明显大于其他纳米管及其2D对应物中的挠曲电。这项工作开辟了JanusIV-VI纳米管的结构-性质关系的途径,并展示了这些纳米管中用于未来电子和能源应用的巨大挠曲电。
    Nanotubes have established a new paradigm in nanoscience because of their atomically thin geometries and intriguing properties. However, because of their typical metastability compared to their 2D and 3D counterparts, it is still fundamentally challenging to synthesize nanotubes with controlled size. New strategies have been suggested for synthesizing nanotubes with a controlled geometry. One of these is considering Janus 2D layers, which can self-roll to form a nanotube. Herein, we study 412 nanotubes (along the armchair and zigzag directions) based on 36 Janus IV-VI compounds using density functional theory (DFT) calculations. By investigating the energy-radius relationship using structural models and Bayesian predictions, the most stable nanotubes show negative strain energies and radii below 20 Å, where curvature effects can play a significant role. The band structures show that the selected nanotubes exhibit sizable band gaps and size-dependent electronic properties. More strikingly, the flexoelectricity along the in-plane directions and radial directions in these nanotubes is significantly larger than that in other nanotubes and their 2D counterparts. This work opens up an avenue of structure-property relationships of Janus IV-VI nanotubes and demonstrates giant flexoelectricity in these nanotubes for future electronic and energy applications.
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