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排序方式: 共有933条查询结果,搜索用时 15 毫秒
1.
纳米尺度下气体驱动液体流动特征在纳流控芯片及页岩气开发中具有广泛的应用前景. 利用管径规格为292.8 nm,206.2 nm,89.2 nm,67.0 nm,26.1 nm的氧化铝膜为纳米阵列,进行气驱水实验和单相气体流动实验,分析纳米尺度下气驱水流动特征. 实验表明,纳米阵列中气驱水时气体流量随驱动压力变化经历三个阶段:第一阶段流量缓慢增大,且比单相气体流量降低约一个数量级;第二阶段纳米阵列中的水被大量驱替出,流量迅速增大;第三阶段纳米阵列中的水全部被驱替出,流动特征与单相气体流动保持一致. 分析表明,气驱水第一阶段存在气液界面毛细管力的“钉扎”作用及固液界面相互作用力的影响,是产生非线性流动的主要原因;而一旦“钉扎”作用破坏,气体进入管道推动界面运动,气柱与液柱之间的毛细曲面曲率变化,毛细管力减小,气体流量急剧增大,其中毛细管力随驱替压力增大急剧变化,是造成第二阶段气体流量突变的主要原因.   相似文献   
2.
丁东  杨仕娥  陈永生  郜小勇  谷锦华  卢景霄 《物理学报》2015,64(24):248801-248801
利用价格低廉、性能优良的金属纳米颗粒增强太阳电池的光吸收具有广阔的应用前景. 通过建立三维数值模型, 模拟了微晶硅薄膜电池前表面周期性分布的Al纳米颗粒阵列对电池光吸收的影响, 并对其结构参数进行了优化. 模拟结果表明: 对于球状Al纳米颗粒阵列, 影响电池光吸收的关键参数是周期P与半径R的比值, 或者说是颗粒的表面覆盖度; 当P/R=4–5时, 总的光吸收较参考电池提高可达20%. 与球状颗粒相比, 优化后的半球状Al纳米颗粒阵列可获得更好的陷光效果, 但后者对颗粒半径R的变化较敏感. 另外, 结合电场分布, 对电池光吸收增强的物理机理进行了分析.  相似文献   
3.
Despite significant progress in development of bioanalytical devices cost, complexity, access to reagents and lack of infrastructure have prevented use of these technologies in resource‐limited regions. To provide a sustainable tool in the global effort to combat infectious diseases the diagnostic device must be low cost, simple to operate and read, robust, and have sensitivity and specificity comparable to laboratory analysis. In this mini‐review we describe recent work using laser machined plastic laminates to produce diagnostic devices that are capable of a wide variety of bioanalytical measurements and show great promise towards future use in low‐resource environments.  相似文献   
4.
将共轭芴类荧光聚合物涂覆在纳米Zn O棒阵列上,制成荧光传感膜检测痕量TNT。通过水热法生长的Zn O纳米棒阵列具有较好的取向性,作为衬底可有效增大荧光膜荧光强度,同时,Zn O纳米棒阵列的高比表面积可提高膜对TNT气体的响应效率,使20s内的荧光猝灭率可达72%。  相似文献   
5.
为了直观、准确地定量分析表面拉曼增强散射基底结构的拉曼增强,利用磁控溅射和高温退火的方法制备了银纳米粒子修饰垂直排列的碳纳米管阵列三维复合结构样品;实验采用罗丹明6G(R6G)溶剂作为探针分子,结合共聚焦显微拉曼系统,开展了表面增强拉曼增强因子(EF)分析计算的相关实验。SEM结果表明:在有序碳纳米管阵列的表面和外壁均匀地负载了大量银纳米粒子。对退火温度为450℃,退火时间为30min的样品进行了EF计算,得到其增强因子约为2.2×103,并分析了EF值低的原因主要是:在碳纳米管上溅射的银膜膜厚不均匀,导致退火后银颗粒分布不均,使得样品粗糙度值偏大,EF值较低;实验中所用的激励光源并非银纳米颗粒的优化光源。  相似文献   
6.
《中国物理 B》2021,30(7):78102-078102
The self-catalyzed growth of Ga As nanowires(NWs) on silicon(Si) is an effective way to achieve integration between group III–V elements and Si. High-crystallinity uniform Ga As NW arrays were grown by solid-source molecular beam epitaxy(MBE). In this paper, we describe systematic experiments which indicate that the substrate treatment is crucial to the highly crystalline and uniform growth of one-dimensional nanomaterials. The influence of natural oxidation time on the crystallinity and uniformity of Ga As NW arrays was investigated and is discussed in detail. The Ga As NW crystallinity and uniformity are maximized after 20 days of natural oxidation time. This work provides a new solution for producing high-crystallinity uniform III–V nanowire arrays on wafer-scale Si substrates. The highly crystalline uniform NW arrays are expected to be useful for NW-based optical interconnects and Si platform optoelectronic devices.  相似文献   
7.
Arrays of anisotropic particles are sought after for applications in optics, electronics, and energy. Structures assembled from multiple micro‐ or nanoparticles could incorporate the distinct properties of each component to achieve functions not possible from single‐population assemblies. In mixed‐particle populations, the assembly forces may differ between the particle types, which will in turn influence the final assembled structures. Here, binary particle mixtures are studied and compared to assemblies formed from each of the component particles alone. The particles are partially etched nanowires (PENs, ≈300 nm diameter, and 3–8 μm overall length), which are formed by the silica coating and subsequent etching of striped metal nanowires, such that what remains are silica nanotubes containing segments of metal core (Au, Pt, Rh, or Pt/Au) with controllable location and number, spaced by “empty” regions that fill with water. Binary mixtures of PENs with different core metals and segment patterns are examined here to explore how the different core segment material, length, position, and number affects overall self‐assembly behavior.  相似文献   
8.
We describe a highly sensitive micro‐solid‐phase extraction method for the pre‐concentration of six phthalate esters utilizing a TiO2 nanotube array coupled to high‐performance liquid chromatography with a variable‐wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2‐ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting‐out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3–200 μg/L. The limits of detection were 0.04–0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples.  相似文献   
9.
A cross-reactive optical sensor array based on poly(p-phenyleneethynylene)s (PPEs) determines Edman degraded amino acids. We report a sensor array composed of three anionic PPEs P1–P3 , and their electrostatic complexes with metal ions (Fe2+, Cu2+, Co2+). We recorded distinct fluorescence intensity response patterns as “fingerprints” of this chemical tongue toward standard phenylthiohydantoin (PTH) amino acids—degradation products of the Edman process. These “fingerprints” were converted into canonical scores by linear discrimination analysis (LDA), which differentiates all of the PTH-amino acids. This array discriminates PTH-amino acid residues degraded from an oligopeptide through Edman sequencing. This approach is complementary to chromatography approaches which rely on mass spectrometry; our array offers the advantage of simplicity.  相似文献   
10.
Recently, Li-ion batteries (LIBs) have attracted extensive attention owing to their wide applications in portable and flexible electronic devices. Such a huge market for LIBs has caused an ever-increasing demand for excellent mechanical flexibility, outstanding cycling life, and electrodes with superior rate capability. Herein, an anode of self-supported Fe3O4@C nanotubes grown on carbon fabric cloth (CFC) is designed rationally and fabricated through an in situ etching and deposition route combined with an annealing process. These carbon-coated nanotube structured Fe3O4 arrays with large surface area and enough void space can not only moderate the volume variation during repeated Li+ insertion/extraction, but also facilitate Li+/electrons transportation and electrolyte penetration. This novel structure endows the Fe3O4@C nanotube arrays stable cycle performance (a large reversible capacity of 900 mA h g−1 up to 100 cycles at 0.5 A g−1) and outstanding rate capability (reversible capacities of 1030, 985, 908, and 755 mA h g−1 at 0.15, 0.3, 0.75, and 1.5 A g−1, respectively). Fe3O4@C nanotube arrays still achieve a capacity of 665 mA h g−1 after 50 cycles at 0.1 A g−1 in Fe3O4@C//LiCoO2 full cells.  相似文献   
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