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[en] Full text: Plasmonics is one of the major parts of nano-optics. When light hits a gold nanoparticle which is smaller than the wavelength, it can resonantly excite coherent electron oscillations (localized surface plasmons) with a strong optical near field enhancement. This effect is promising for several applications in sensor technology. The spectral position and strength of localized surface plasmons depends on the shape and the roughness of the nano-particle. We investigate the influence of nanometric surface roughness of gold nano-particles on the optical near fields with the aim to optimize them. We modify the surface roughness by varying the production parameters and by following annealing. Our investigation methods include AFM, SEM and spectrometry. Our results indicate sharper resonance peaks in the absorbance spectrum for smoother surfaces. (author)
[en] Highlights: • Hydrophobic materials determines the critical roughness to maintain a composite wetting state. • Critical roughness has no necessary relation with surface fractal dimension. • Such critical roughness has scope of [1.85, 5.00], when intrinsic contact angle ranges from 100° to 120°. • Surface fractal is not unique for superhydrophobicity, only a means to obtain high roughness. • There exists obvious difference of adhesion work between composite and non–composite wetting state. - Abstract: Solid–liquid contact state between water droplets and Superhydrophobic surface (SHS) is mainly determined by the microstructures of a surface. Composite and non–composite wetting states (NCWS) even together with their mixture are generally regarded as basic states. For an SHS, a composite wetting state (CWS) is more preferred due to water droplet easier to slide. Therefore, determining a critical roughness to form, then to maintain such a state has profound significance for fabrication of SHS. For this reason, we propose a thermodynamic methodology based on a three–dimensional (3–D) pillar model, integrating wetting states (WS) with interfacial energy, to obtain the corresponding critical roughness for the reference of micromachining. By calculating, we found that the critical roughness for a transition from NCWS to CWS changes with inherent materials from aspect of adhesion work; furthermore, if given hydrphobic materials, such roughness is also given and not relevant to the fractal dimension of an SHS. Therefore, the hydrophobic materials determine the transition. Meanwhile, we also proved the above finds by interfacial energy and contact angle (CA) varying with the roughness.
[en] The proposed planetary reaming method permits discontinuous turning in which the cutting edge moves relative to the cutting surfaces. As a result, individual sections of the cutting zone move successfully in and out of the machining zone. Discontinuous turning is free of the deficiencies of continuous turning.
[en] In this report, the surface hydrophobicity of PDMS was investigated using two methods of preparations. The first method was performed by changing the surface roughness through the use of different molds. The second method was performed by varying the reconstitution ratio (volume of elastomer base to volume of elastomer curing) of the PDMS. Variation in the hydrophobicity of the PDMS was characterized by measuring the contact angle of a liquid droplet against the surface of the PDMS. The results showed that both the surface roughness and the reconstitution ratio of the PDMS positively correlated with the contact angle measured regardless of the liquid used. The maximum and minimum contact angle obtained were θ_r = (138 ± 3)° and θ_r = (99 ± 3)°, respectively. The results demonstrate a straightforward way of fabricating microfluidic devices using PDMS with controlled hydrophobicity. (paper)
[en] Even though many techniques have been used in the research for the quality of a surface, the effect of each cutting condition on the surface roughness has yet to be definitely determined. In the present study, the cause of the contradictory effect of the cutting condition was explained. As a result, the cutting velocity was found to be an improper cutting parameter for explaining variations in surface roughness. It was also discovered that the depth of cut could affect the surface roughness, contrary to the claims of most publications. Consequently, the optimum cutting conditions were determined for the finest surface roughness, and were proven to be significantly better than those obtained using the Taguchi method and methods described in the literature.
[en] This paper is to analyze the surface roughness in wet and dry surface grinding in which working conditions are table feed, cross feed and down feed. FFT analyzer is used to identify the surface roughness and the data of surface roughness are stored and displayed using an interfaced computer. In results, components affecting surface roughness exist within 200Hz with respect the conditions and methods of grinding operation. Also, with increase of table feed, cross feed and down feed, the value of surface roughness increases. Of them, cross feed has first influence on surface roughness. In dry, more precise surface can be obtained than one in wet