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A simple two-dimensional model of thin film growth based on the ballistic aggregation of hard discs is proposed. In this model the impinging hard discs travel in a straight line and initially ‘stick’ to the first previously deposited hard disc they contact. Previously (Dirks and Leamy 1977 Thin Solid Films 47 219) the criterion for relaxation has been migration of the impinging disc to the nearest pocket formed by two additional discs. In the model proposed here, however, relaxation is dependent on the surrounding geometry of the previously deposited atoms. The deposited disc may ‘relax’ into a position where it then makes contact with three, two or one previously deposited disc(s). The influences of substrate temperature, deposition rate, angle of incidence, self-shadowing effect and substrate roughness, including amorphous substrates are investigated. Results are qualitatively in good agreement with the structure zone model (SZM) predictions for thin metallic films.

The present study demonstrated the simple, cheap, eco-friendly synthesis of the silver nanoparticles (S-AgNPs) using Symphytum officinale leaf extract. The biosynthesized S-AgNPs were characterized by UV-Vis, FE-TEM, elemental mapping, EDX, zeta potential, XRD, SAED, and FT-IR. The characterization results revealed the irregular shape and relatively stable nature of synthesized S-AgNPs. The average particle size was determined to be 87.46 nm. The zeta potential shows the negative surface charge (− 25.5 mV) of S-AgNPs. After characterization, we investigated the anti-aging effect of S-AgNPs in HaCaT keratinocyte cells. HaCaT keratinocyte cells were treated with S-AgNPs at concentrations 1, 10, 100 μg mL −1 after UVB or non-UVB irradiation. The S-AgNPs significantly inhibited the production of matrix metalloproteinase-1 and IL-6 but increased the expression of procollagen type 1. The data suggest that S-AgNPs have photoprotective properties and may have potential to be used as an agent against photoaging. Graphical abstractElectronic supplementary material The online version of this article (https ://doi.org/10.1007/s4009 7-018-0281-6) contains supplementary material, which is available to authorized users.

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This paper is an attempt to compare the influence of various annealing conditions on growth, nanostructure, surface morphology and electrical properties of copper oxide thin films. Cu thin films of 85 nm thickness were deposited on glass substrate by thermal evaporation method, and then post-annealed at different environments (air and oxygen flow), different temperatures (200-400°C) and different times (35 and 75 min). X-ray diffraction results showed (Cu 2 O) cuprite phase for all annealed samples at 200 and 250°C and (CuO) tenorite phase for all samples annealed under different conditions at 350 and 400°C. A complex phase of CuO and Cu 2 O was observed for all annealed samples at 300°C, with exception for the sample annealed with flow of oxygen for 75 min. The atomic force microscopy results showed that surface morphology of the samples was strongly affected by the changes of annealing conditions (i.e., time, temperature and environment). The size of the grains increased with annealing temperature and time, while the samples annealed with oxygen flow showed larger grains than those annealed in air. Two different behaviors with annealing temperature were distinguished for the surface roughness of the samples annealed in the air and those annealed with flow of oxygen. Resistivity and Hall effect of samples were measured by a four-point probe instrument and a Hall effect investigation system, respectively. The electrical analyses showed that the variations in annealing conditions had a remarkable effect on measured electrical parameters, namely films resistivity, carriers concentration and type, and Hall mobility.