The development of complex nanostructures containing a homo‐ and heteromixture of two or more metals is a considerable challenge in nanotechnology. However, previous approaches are considerably limited to the number of combinations of metals depending on the compatibility of elements, and to the complex shape control of the nanostructure. In this study, a significant step is taken toward resolving these limitations via the utilization of a low‐energy argon‐ion bombardment. The multilayer films are etched and re‐sputtered on the sidewall of the pre‐pattern, which is a secondary sputtering phenomenon. In contrast to the precursor mixing method, most metallic combinations can be fabricated. The degree of mixing is tuned by the control of the sequence and thickness of multilayers. In addition, the feature shape and dimensions are controlled by changing the pre‐pattern or by controlling the ion‐beam angle. Using this method, the shortest response time (2 s to 1% H2) in comparison with those of Pd‐based H2 sensors reported previously and a limit of detection below 1 parts per million (ppm) for Pd/Au and Pd/Pt bimetallic line arrays are achieved. This study is expected to realize a family of polyelements that can be used in various applications. 相似文献
The functionalization of graphene has been extensively used as an effective route for modulating the surface property of graphene, and enhancing the dispersion stability of graphene in aqueous solutions via functionalization has been widely investigated to expand its use for various applications across a range of fields. Herein, an effective approach is described for enhancing the dispersibility of graphene in aqueous solutions at different pH levels via non‐covalent zwitterion functionalization. The results show that a surfactant with electron‐deficient carbon atoms in its backbone structure and large π–π interactive area enables strong interactions with graphene, and the zwitterionic side terminal groups of the molecule support the dispersibility of graphene in various pH conditions. Experimental and computational studies confirm that perylene diimide amino N‐oxide (PDI–NO) allows efficient functionalization and pH‐independent dispersion of graphene enabled by hydration repulsion effects induced by PDI–NO. The PDI–NO functionalized graphene is successfully used in the oxygen evolution reaction as an electron mediator for boosting the electrocatalytic activity of a Ru‐based polyoxometalate catalyst in an acidic medium. The proposed strategy is expected to bring significant advances in producing highly dispersible graphene in aqueous medium with pH‐independent stability, thus broadening the application range of graphene. 相似文献
An efficient video retrieval system is essential to search relevant video contents from a large set of video clips, which typically contain several heterogeneous video clips to match with. In this paper, we introduce a content-based video matching system that finds the most relevant video segments from video database for a given query video clip. Finding relevant video clips is not a trivial task, because objects in a video clip can constantly move over time. To perform this task efficiently, we propose a novel video matching called Spatio-Temporal Pyramid Matching (STPM). Considering features of objects in 2D space and time, STPM recursively divides a video clip into a 3D spatio-temporal pyramidal space and compares the features in different resolutions. In order to improve the retrieval performance, we consider both static and dynamic features of objects. We also provide a sufficient condition in which the matching can get the additional benefit from temporal information. The experimental results show that our STPM performs better than the other video matching methods. 相似文献
This paper proposes a simple framework for constructing a stabilizer code with an arbitrary binary matrix. We define a relation between A1 and A2 of a binary check matrix A = (A1|A2) associated with stabilizer generators of a quantum error-correcting code. Given an arbitrary binary matrix, we can derive a pair of A1 and A2 by the relation. As examples, we illustrate two kinds of stabilizer codes: quantum LDPC codes and quantum convolutional codes. By the nature of the proposed framework, the stabilizer codes covered in this paper belong to general stabilizer (non-CSS) codes. 相似文献
MWNT/nylon 6, 6 composite nanofibers were fabricated using an electrospinning method, and the electrical properties were examined as a function of the filler concentration. Initially, the pristine, purified MWNTs were treated with a 3:1 mixture of concentrated H2SO4/HNO3 to introduce carboxyl groups onto the MWNT surface. The carboxylated MWNTs were then treated with thionyl chloride and an ethylenediamine solution for amide functionalization. FT-IR spectroscopy was used to examine the functionalization of the MWNTs. Nylon 6, 6 is readily soluble in formic acid. Therefore, the amide functionalized MWNTs were dispersed in formic acid. The solution remained stable and uniform for more than 40 h. –NH2 termination of the MWNTs improved the dispersion stability of the MWNTs in formic acid. The MWNTs-suspended in a solution of nylon 6, 6 in formic acid was electrospun to obtain the nanofibers. The electrical properties of the nanofibers were examined as a function of the filler concentration. The results showed that the I–V properties of the nanofiber sheet improved with increasing filler concentration. 相似文献
The effects of potassium or lanthanum additives on the catalytic properties of alumina-supported cobalt catalysts were examined
through carbon monoxide hydrogenation reaction. The catalysts were characterized by hydrogen or carbon monoxide chemisorption,
oxygen titration, and temperature-programmed desorption. The reactions were carried out at 270 °C and atmospheric pressure.
When a small amount of potassium was added to alumina-supported cobalt catalysts, the amount of hydrogen adsorption decreased
more significantly than that of carbon monoxide adsorption, and the extent of reduction also decreased. With the addition
of potassium, the overall carbon monoxide conversion decreased, while the selectivity to higher hydrocarbon and olefin increased.
The effect of lanthanum on activity and selectivity in carbon monoxide hydrogenation was less significant than the effect
of potassium. Temperature-programmed desorption showed that the presence of additives changed the adsorbed state of CO on
cobalt.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
Preferential CO oxidation reaction has been carried out at a gas hourly space velocity of 46,129 h?1 over supported Pt catalysts prepared by an incipient wetness impregnation method. Al2O3, MgO-Al2O3 (MgO=30 wt% and 70 wt%) and MgO were employed as supports for the target reaction. 1 wt% Pt/Al2O3 catalyst exhibited very high performance (XCO>90% at 175 °C for 100 h) in the reformate gases containing CO2 under severe conditions. This result is mainly due to the highest Pt dispersion, easier reducibility of PtOx, and easier electron transfer of metallic Pt. In addition, 1 wt% Pt/Al2O3 catalyst was also tested in the reformate gases with both CO2 and H2O to evaluate under realistic condition. 相似文献
The thermal expansion and ionic conduction of 15 mol% CaO‐stabilized zirconia (CSZ) with added Al2O3 were investigated. Specimens with 0.5 and 1 mol% Al2O3 maintained the cubic phase, and the thermal diffusivity increased from 0.499 to 0.661 mm2/s with a 1 mol% addition. The addition of 5 mol% caused a decrease in the thermal diffusivity (0.609 mm2/s) with the formation of the monoclinic phase. The thermal expansion coefficient of the CSZ decreased, and the thermal diffusivity increased with the addition of Al2O3. The ionic conductivity was increased up to the addition of 1 mol% due to scavenging of siliceous by Al2O3, while the 5 mol% addition showed a decrease in conductivity with the formation of the intergranular phase. 相似文献
During the Chemical mechanical planarization (CMP), the pad conditioning process can affect the pad surface characteristics. Among many CMP process parameters, the improper applied load on the conditioner arm may have adverse effects on the polyurethane pad. In this work, we evaluated the pad surface properties under the various conditioner arm applied during pad conditioning process. The conditioning pads were evaluated for surface topography, surface roughness parameters such as Rt and Rvk and Material removal rate (MRR) and within-wafer non-uniformity after wafer polishing. We observed that, the pad asperities were collapsed in the direction of conditioner rotation and blocks the pad pores applied conditioner load. The Rvk value and MRR were founded to be in relation with 4 > 1 > 7 kgF conditioner load. Hence, this study shows that, 4 kgF applied load by conditioner is most suitable for the pad conditioning during CMP.