High-performance carbon nanotube light-emitting diodes with asymmetric contacts

Electroluminescence (EL) measurements are carried out on a two-terminal carbon nanotube (CNT) based light-emitting diode (LED). This two-terminal device is composed of an asymmetrically contacted semiconducting single-walled carbon nanotube (SWCNT). On the one end the SWCNT is contacted with Sc and on the other end with Pd. At large forward bias, with the Sc contact being grounded, electrons can be injected barrier-free into the conduction band of the SWCNT from the Sc contact and holes be injected into the valence band from the Pd electrode. The injected electrons and holes recombine radiatively in the SWCNT channel yielding a narrowly peaked emission peak with a full width at half-maximum of about 30 meV. Detailed EL spectroscopy measurements show that the emission is excitons dominated process, showing little overlap with that associated with the continuum states. The performance of the LED is compared with that based on a three-terminal field-effect transistor (FET) that is fabricated on the same SWCNT. The conversion efficiency of the two-terminal diode is shown to be more than three times higher than that of the FET based device, and the emission peak of the LED is much narrower and operation voltage is lower.     

风机叶片用环氧树脂的固化动力学研究

通过动态DSC(差示扫描量热法)研究了佳发JH-239、惠利LT-5078A等两种风机叶片用环氧树脂的固化动力学特征温度,并采用Kissinger、Crane法确定它们的固化动力学参数.结果表明:佳发树脂体系的表现活化能为40.60 kJ/mol,惠利树脂体系的表现活化能为45.91kJ/mol,而二者的反应级数分别为...     

High Phase Purity of Large‐Sized 1T′‐MoS2 Monolayers with 2D Superconductivity

The development of transition metal dichalcogenides has greatly accelerated research in the 2D realm, especially for layered MoS₂. Crucially, the metallic MoS₂ monolayer is an ideal platform in which novel topological electronic states can emerge and also exhibits excellent energy conversion and storage properties. However, as its intrinsic metallic phase, little is known about the nature of 2D 1T′‐MoS₂, probably because of limited phase uniformity (<80%) and lateral size (usually <1 µm) in produced materials. Herein, solution processing to realize high phase‐purity 1T′‐MoS₂ monolayers with large lateral size is demonstrated. Direct chemical exfoliation of millimeter‐sized 1T′ crystal is introduced to successfully produce a high‐yield of 1T′‐MoS₂ monolayers with over 97% phase purity and unprecedentedly large size up to tens of micrometers. Furthermore, the large‐sized and high‐quality 1T′‐MoS₂ nanosheets exhibit clear intrinsic superconductivity among all thicknesses down to monolayer, accompanied by a slow drop of transition temperature from 6.1 to 3.0 K. Prominently, unconventional superconducting behavior with upper critical field far beyond the Pauli limit is observed in the centrosymmetric 1T′‐MoS₂ structure. The results open up an ideal approach to explore the properties of 2D metastable polymorphic materials.     

Scanning Nanowelding Lithography for Rewritable One‐Step Patterning of Sub‐50 nm High‐Aspect‐Ratio Metal Nanostructures

The development of a new nanolithographic strategy, named scanning nanowelding lithography (SNWL), for the one‐step fabrication of arbitrary high‐aspect‐ratio nanostructures of metal is reported in this study. Different from conventional pattern transfer and additive printing strategies which require subtraction or addition of materials, SNWL makes use of a sharp scanning tip to reshape metal thin films or existing nanostructures into desirable high‐aspect‐ratio patterns, through a cold‐welding effect of metal at the nanoscale. As a consequence, SNWL can easily fabricate, in one step and at ambient conditions, sub‐50 nm metal nanowalls with remarkable aspect ratio >5, which are found to be strong waveguide of light. More importantly, SNWL outweighs the existing strategies in terms of the unique ability to erase the as‐made nanostructures and rewrite them into other shapes and orientations on‐demand. Taking advantages of the serial and rewriting capabilities of SNWL, the smart information storage–erasure of Morse codes is demonstrated. SNWL is a promising method to construct arbitrary high‐aspect‐ratio nanostructure arrays that are highly desirable for biological, medical, optical, electronic, and information applications.     

纳米羟基磷灰石/聚酰胺66复合材料在模拟体液(SBF)中的表面生物活性研究

通过纳米羟基磷灰石／聚酰胺66(n—HA／PA66)复合材料体外模拟体液(SBF)浸泡实验，以聚酰胺66(PA66)为对照，用IR、XRD、SEM和ICP等手段对材料的表面组成和形貌变化进行了分析，比较了PA66和n-HA／PA66复合材料的表面生物活性。结果表明，n-HA／PA66复合材料在SBF中其表面形成的HA沉积物为部分碳酸基团取代的磷灰石，而PA66在浸泡过程中Ca、P不在聚合物表面沉积；n-HA／PA66复合材料具有良好的生物活性，作为骨组织修复或替代材料具有较高的研究和应用价值。     

高流动性星型尼龙12的合成与表征

在均苯三甲酸的存在下,进行十二内酰胺的水解聚合,合成了四种不同臂长的三臂星型尼龙12,对产物的分子量进行了测定,并对其力学性能和流变行为进行了研究。结果表明,星型尼龙12的分子量随着均苯三甲酸含量的提高而降低,与相应分子量的线型尼龙12相比,星型尼龙12的拉伸强度和弯曲强度基本保持,冲击强度保持率在80%以上,断裂伸长...     

A2N反硝化除磷脱氮系统处理生活污水研究

研究了生活污水COD／TN比值变化对A2N反硝化除磷脱氮新工艺去除氮、磷的影响情况。同时利用间歇试验着重探讨了DNPAOs污泥在不同硝态氮浓度、不同电子受体时的摄磷和放磷状况。A2N连续流工艺长期的运行结果表明：双泥系统的建立(生物膜硝化池独立于除磷污泥)可以降低碳源的好氧消耗,较大程度地减少聚磷菌和反硝化菌之间对碳源的竞争,同时保证了生长速率较小的硝化菌可以在稳定状态中生长,利于增强系统脱氮除磷的稳定性。