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排序方式: 共有1038条查询结果,搜索用时 15 毫秒
71.
72.
二甲基—γ—全氟辛酰氧丙基硅烷自组装膜的制备及其摩擦学性能研究 总被引:4,自引:2,他引:4
利用分子自组装技术 ,用含有全氟烷基的氯硅烷作为前驱体 ,在活化玻璃表面制备了二甲基 -γ-全氟辛酰氧丙基硅烷单分子膜 ;用 X射线光电子能谱仪对组装膜表面的几种特征元素及其化学环境进行了表征 ;采用接触角测定仪测定了蒸馏水在自组装薄膜表面的接触角 ,在动静摩擦磨损试验机上评价了薄膜同 GCr1 5钢球对摩时的摩擦磨损性能 .结果表明 :所制备的自组装膜的表面自由能很低 ,具有很好的疏水 -疏油性 ,其对水的接触角高达 1 1 0°;二甲基 -γ-全氟辛酰氧丙基硅烷组装膜可以降低基片的摩擦系数 ,而且在较低负荷下具有很好的耐磨性 相似文献
73.
74.
Wen-Rong Liu 《中国物理 B》2022,31(3):37305-037305
The two-dimensional (2D) materials with nodal line band crossing have been attracting great research interest. However, it remains a challenge to find high-stable nodal line structure in 2D systems. Herein, based on the first-principles calculations and theoretical analysis, we propose that monolayer B6O possesses symmetry protected Dirac nodal line (DNL) state, with its Fermi velocity of 106 m/s in the same order of magnitude as that of graphene. The origin of DNL fermions is induced by coexistence of time-reversal symmetry and inversion symmetry. A two-band tight-binding model is further given to understand the mechanism of DNL. Considering its robustness against spin—orbit coupling (SOC) and high structural stability, these results suggest monolayer B6O as a new platform for realizing future high-speed low-dissipation devices. 相似文献
75.
Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route 总被引:1,自引:0,他引:1
Li Wen Zhonghua Lin Pingying Gu Jianzhang Zhou Bingxing Yao Guoliang Chen Jinkun Fu 《Journal of nanoparticle research》2009,11(2):279-288
Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly
by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 °C. The kinetics of gold nanoparticle
formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time
was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and
dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could
induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the
monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold
nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01. 相似文献
76.
Naumih M. Noah Omole Marcells Anas Almalleti Jae Lim Omowunmi A. Sadik 《Electroanalysis》2011,23(10):2392-2399
Pain measurement is commonly required in biomedical and other emergency situations, yet there has been no pain biosensor reported in literature. Conventional approaches for pain measurement relies on Wong‐Baker face diagrams, which are grossly inadequate for situations involving children or unconscious people. We report a label‐free immunosensor for monitoring the pain biomarker cylooxygenase‐2 (COX‐2) in blood. The sensor is based on the concept of metal‐enhanced detection (MED). MED relies on the idea that the immobilization of underpotential deposition (upd) metallic films deposited either as a monolayer or electrostatically held onto a solid gold substrate could significantly amplify bimolecular recognition such as involving antigen‐antibody (Ab‐Ag) interactions. The surface bound Ab‐Ag complex insulates the electrode; causing a decrease in concentration‐dependent redox signals. A linear detection range of (3.64–3640.00)×10?4 ng/mL was recorded with a detection limit of 0.25×10?4 ng/mL, which was 4 orders of magnitude lower than that reported for ELISA for the same biomarker. The immunosensor exhibited selectivity of less than 6 % for potential interferents. 相似文献
77.
Dr. Jiu Chen Prof. Dr. Qing Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(38):9925-9933
The recent successful growth of MoSi2N4 and WSi2N4 monolayers led to the discovery of a new class of the two-dimensional (2D) MA2Z4 materials with no known 3D layered allotropes, which renders great possibilities to integrate diverse properties by proper design of sandwiched “MZ2” building blocks and “A−Z” passivation layers. In this work, the dynamic stability, electronic properties, and surface reactivity of the new MA2Z4 family, in which M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, A refers to Si or Ge, and Z is N, P or As, is theoretically probed. Among the proposed 54 possible combinations, about 42 compositions are dynamically stable, which vary from non-magnetic, anti-ferromagnetic, to ferromagnetic semiconductors, metals and half-metals. In particular, the VB (V, Nb, Ta) MA2Z4 possesses robust intrinsic ferromagnetism that is essential for spintronics applications. In regard to surface activity, most MA2Z4, particularly N- or P-terminated IVB and VB MA2Z4, have high catalytic potential for hydrogen evolution, and the ▵GH of non-magnetic MA2Z4 is highly correlated to the highest occupied p electronic states of the surface Z atoms. The photocatalytic activity is also evaluated. MoSi2N4 and WSi2N4 within 4 % tensile strain are capable of photocatalytic overall water splitting. The findings indicate the new 2D MA2Z4 family has fascinating properties and possesses strong potential for applications but not limited to electronics, spintronics and catalysts, which will stimulate the interests of experimental synthesis. 相似文献
78.
Fourier transform surface enhanced Raman spectrometer is used to characterize Ω-mercaptoalkanols (HO(CH2)nSH, n=2, 6) chemisorption on silver surface from their aqueous solution of different pH values. 相似文献
79.
《Analytical letters》2012,45(7):1226-1240
In this paper, we described a novel sensor based on tiron-doped polypyrrole and carbon nanotubes (CNTs) fabricated on low resistance monolayer-modified glassy carbon electrode. First, the dodecylamine monolayer was chemically modified. Second, CNTs were controllably adsorbed onto dodecylamine. Then, tiron doped polypyrrole was electro-deposited on the CNTs film. The layer-by-layer modified electrode was sensitive to dopamine, while it made no response to even high concentration of ascorbic acid. Parameters influencing the dopamine response were optimized. High performance of the sensor was obtained, such as wide concentration range, low detection limit (3 nM), low background current, high stability, and reproducibility. 相似文献
80.
Single-component monolayer of novel multi-thiol coronary molecule and two-component mixed monolayer composed of coronary molecule and n-alkanethiol on gold substrates are described. The assembly of monolayers is characterized by ellipsometry, infrared spectroscopy and X-ray photoelectron spectroscope. The electrochemical properties of the single- and two-component monolayers are evaluated by cyclic voltammetry and electrochemical impedance spectroscopy experiments. Coronary molecule with multi-thiol groups has the ability to form stable monolayer via the interaction of mercapto groups and Au surface. Electrochemical impedance measurements indicate that 89.9% of the gold surface is blocked by the coronary molecule, which is attributed to the special spatial structure of the coronary molecule. The uncovered site on gold surface in coronary molecule monolayer could be occupied by the second suitable molecule. The mixed monolayer prepared by stepwise assembly of coronary molecule and n-alkanethiol has complete compact packing and few defects. 相似文献