The thermal conductivity of individual single-crystalline Bi nanowires grown by the on-film formation of nanowires (ON-OFF) has been investigated. We observed that the thermal conductivity of single-crystalline Bi nanowires is highly anisotropic. Thermal conductivity of nanowires (diameter ∼100 nm) in the off-axis [102] and [110] directions exhibits a difference of ∼7.0 W/m·K. The thermal conductivity in both growth directions is diameter-dependent, which indicates that thermal transport through the individual Bi nanowires is limited by boundary scattering of both electrons and phonons. This huge anisotropy in thermal conductivities of Bi nanowires suggests the importance of direction-dependent characterization of charge, thermal transport, and thermoelectric properties of Bi nanowires.
Twelve new diarylheptanoids and six known compounds were isolated from rhizomes of Curcuma kwangsiensis. Structures of the new compounds were elucidated by spectroscopic and chemical methods as (3S)- and (3R)-1,7-bis(4-hydroxyphenyl)-(6E)-6-hepten-3-ol (1a and 1b), (3S)- and (3R)-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-(6E)-6-hepten-3-ol (2a and 2b), (3S)- and (3R)-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)heptan-3-ol (3a and 3b), (3R)-1-(3,4-dihydroxyphenyl)-7-phenyl-(6E)-6-hepten-3-ol (4b), (3S)- and (3R)-3-acetoxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-(6E)-6-heptene (5a and 5b), (3S)- and (3R)-3-acetoxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)heptanes (6a and 6b), and (E)-1,7-bis(4-hydroxyphenyl)-6-hepten-3-one (7). The absolute configurations were determined using the modified Mosher's method. Separation of the enantiomeric mixtures (1a and 1b, 2a and 2b, 3a and 3b, 4a and 4b, 5a and 5b, 6a and 6b) was achieved on a chiral column using acetonitrile-water mixtures as eluents. The S enantiomers exhibited negative specific optical rotations in MeOH, and the R enantiomers were positive. Inhibitory effects of the compounds on nitric oxide production in lipopolysaccaride-activated macrophages were evaluated.
Aiming at the current situation of long cycle and high cost for planetary reduction gears designing and manufacturing in the field of engineering machinery, analysis on the environment has been established by using reducer virtual prototype in this paper, simultaneously the article brings forward a strong realization system from virtual simulation to finite element analysis. The results show that the virtual prototype model possesses high reliability and rapid correction method, it can shorten the design cycle greatly, and the method has certain practical application value.
CrAlTiCN multilayer films have been prepared by closed-field unbalanced magnetron sputtering technology using graphite target as the C supplier. TEM observation results show that the CrAlTiCN films have a clear multilayer structure with the modulate periods changed with the current of graphite target. The higher the current of graphite target, the thicker the periodical thickness of multilayer film. The microstructure of CrAlTiCN films is that the (Cr,Al,Ti)N/amorphous carbon multilayer where (Cr,Al,Ti)N layer and amorphous carbon layer appeared interval, the volume fraction of the amorphous carbon increased with the increasing current of graphite target. Measurement results showed that the CrAlTiCN multilayer films have high microhardness and low friction coefficient. Based on the relationship of the microstructure and properties of films, the multilayer structure and fine grain size of (Cr,Al,Ti)N phase are responsible for their excellent mechanical properties. The good tribological properties are attributed to the amorphous carbon phase (sp2C-C).
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