1,721,742 research outputs found
Replication Data for: Asteriquinones from Aspergillus sp. GZWMJZ-258 and Their Derivatives
No full textnmr data for compounds 1-1
Infrared frequency-tunable coherent thermal sources
Full text linkabstract: In this work, we numerically demonstrate an infrared (IR) frequency-tunable selective thermal emitter made of graphene-covered silicon carbide (SiC) gratings. Rigorous coupled-wave analysis shows temporally-coherent emission peaks associated with magnetic polariton (MP), whose resonance frequency can be dynamically tuned within the phonon absorption band of SiC by varying graphene chemical potential. An analytical inductor–capacitor circuit model is introduced to quantitatively predict the resonance frequency and further elucidate the mechanism for the tunable emission peak. The effects of grating geometric parameters, such as grating height, groove width and grating period, on the selective emission peak are explored. The direction-independent behavior of MP and associated coherent emission are also demonstrated. Moreover, by depositing four layers of graphene sheets onto the SiC gratings, a large tunability of 8.5% in peak frequency can be obtained to yield the coherent emission covering a broad frequency range from 820 to 890 cm[superscript −1]. The novel tunable metamaterial could pave the way to a new class of tunable thermal sources in the IR region.Copyright IOP Publishing. This is the authors' final, peer-reviewed manuscript. Wang, Hao, Yang, Yue, & Wang, Liping (2015). Infrared frequency-tunable coherent thermal sources. JOURNAL OF OPTICS, 17(4), 0-0. http://dx.doi.org/10.1088/2040-8978/17/4/045104. The final version as published can be viewed online at http://dx.doi.org/10.1088/2040-8978/17/4/04510
A new species of Homalota Mannerheim, 1830 (Coleoptera: Staphylinidae: Aleocharinae) from Nanjing, China
No full textCao, Dandan, Wei, Jianrong, Liu, Shuwen, Zhao, Zhengping, Wang, Liping, Ji, Baozhong (2018): A new species of Homalota Mannerheim, 1830 (Coleoptera: Staphylinidae: Aleocharinae) from Nanjing, China. Zootaxa 4444 (3): 327-332, DOI: 10.11646/zootaxa.4444.3.
FIGURES 19–20 in A new species of Homalota Mannerheim, 1830 (Coleoptera: Staphylinidae: Aleocharinae) from Nanjing, China
No full textFIGURES 19–20. Homalota nanjingensis Cao, Ji, Liu, sp. nov. 19 median lobe, ventral view (scale bar = 0.08 mm); 20 paramere, lateral aspect (scale bar = 0.08 mm).Published as part of Cao, Dandan, Wei, Jianrong, Liu, Shuwen, Zhao, Zhengping, Wang, Liping & Ji, Baozhong, 2018, A new species of Homalota Mannerheim, 1830 (Coleoptera: Staphylinidae: Aleocharinae) from Nanjing, China, pp. 327-332 in Zootaxa 4444 (3) on page 331, DOI: 10.11646/zootaxa.4444.3.7, http://zenodo.org/record/130972
Structure and mechanical properties of reactive sputtering CrSiN films
Full text linkCrSiN films with various Si contents were deposited by reactive magnetron sputtering using the codeposition of Cr and Si targets in the presence of the reactive gas mixture. Comparative studies on microstructure and mechanical properties between CrN and CrSiN films with various Si contents were carried out. The structure of the CrSiN films was found to change from crystalline to amorphous structure as the Si contents increase. Amorphous phase of Si3N4 compound was suggested to exist in the CrSiN film. The growth of films has been observed from continuous columnar structure, granular structure to glassy-like appearance morphology with the increase of silicon content. The film fracture changed from continuous columnar structure, granular structure to glassy-like appearance morphology with theincrease of silicon content. Two hardness peaks of the films as function of Si contents have been discussed
Fabrication of CrAlN nanocomposite films with high hardness and excellent anti-wear performance for gear application
No full textCrAlN nanocomposite films with various Al contents were prepared by a reactive magnetron sputteringtechnique using Cr and Al targets in the reactive gas mixture. The micro-structure, mechanical properties andtribological behaviors of traditional CrN and newly-fabricated CrAlN nanocomposite films were compared.XRD results showed that single-phase fcc (face-centered cubic) CrAlN films formed a solid solution wherebyCr atoms were substituted by Al atoms. High resolution TEM results demonstrate that the CrAlN filmpossesses a unique amorphous/crystalline nanocomposite micro-structure with ?5 nm crystalline uniformlyembedded into an amorphous matrix. In addition, CrAlN nanocomposite films exhibited relatively smallergrain size and denser structure when compared with CrN films. All the CrAlN nanocomposite films with thehighest hardness being approximately 33.4 GPa exhibited much higher hardness and better wear resistancethan traditional CrN films The excellent anti-wear performance of CrAlN nanocomposite films can beattributed to an amorphous/crystalline nanocomposite micro-structure and their high hardness. CrAlNnanocomposite films are considered as potential protective surfaces for such kinds of moving parts as gears,cutting tools and shafts used in engine and other mechanical mechanisms
The electrodeposition and characterisation of low-friction and wear-resistant Co-Ni-P coatings
No full textA new Co-Ni-P coating having superior properties to hard chrome coatings for anti-wear applications has been developed by combining the precipitation hardening of Ni-P alloys with the lubricity of cobalt-rich Co-Ni coatings. The evolution of composition andmicrostructure, hardness, thermal stability and tribological properties have been investigated. The local pH value near the cathode played an important role in the change of the microstructure from nanocrystalline to amorphous along the growth direction as the phosphorous content increased from 7 at.% to 26 at.%. The highest microhardness (980 HV) and the lowest wear rate (one order of magnitude lower than that of hard chrome coatings under the same dry sliding conditions) were achieved by annealing the coatings at 400 °C facilitating precipitation hardening. Furthermore, the coefficients of friction of both the as-deposited Co-Ni-P coating and the heat-treated sampleswere approximately 0.3, only half of that of hard chrome coatings. The wear rates of Co-Ni-P coatings annealed up to 400 °C are 4–7 times lower compared to that of hard chrome. The roll-like debris found on the worn surfaces of the coating annealed at 500 °C were oriented perpendicularly to the sliding direction. Such part might be related to the slightly reduced coefficient of friction in the stable stag
Tailoring microstructure and phase segregation for low friction carbon-based nanocomposite coatings
Full text linkFriction has a direct relation with the energy efficiency and environmental cleanliness in all moving mechanical systems. To develop low friction coatings is extremely beneficial for preserving not only our limited energy resources but also the earth’s environment. This study proposes a new design for low friction carbon-based nanocomposite coatings by tailoring the microstructure and phase segregation,and thereby it contributes to better controlling the mechanical and tribological properties. Experimental findings and theoretical calculations reveal that high-hardness (18.2 GPa), high-adhesion strength (28 N) as well as low-internal stress (-0.8 GPa) can be achieved by a nanocrystallite/amorphous microstructure architecture for the nc-WC/a-C(Al) carbon-based nanocomposite coating;in particular low friction (~0.05) can be acquired by creating a strong thermodynamic driving force to promote phase segregation of graphitic carbon from the a-C structure so as to form a low shear strength graphitic tribo-layer on the friction contact surfaces. This design concept is general and has been successfully employed to fabricate a wide class of low friction carbon-based nanocomposite coating
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