Hydrothermal Growth of Vertical ZnO Nanorods

Vertically aligned, single crystalline ZnO nanorods with a high packing density and diameter of ∼60 nm have been successfully synthesized via a low-temperature hydrothermal route on glass substrates pre-deposited with a ZnO seeding layer. The seeding layer exhibits an epitaxial effect on the growth and alignment of the ZnO nanorods. This epitaxial effect can arise from two considerations, namely the crystalline orientation and surface roughness of the seeding layer, which can be controlled by the curing temperature. The ZnO seeding layer that was cured at 350°C exhibited a preferred (0002) crystalline orientation of wurtzite hexagonal structure and a low surface roughness. It was demonstrated to promote the vertical growth of ZnO nanorods. The ZnO nanorods grew in an almost linear relationship with hydrothermal time up to 8 h, but thereafter started to dissolve as the reaction time extended beyond 8 h, due to competition from the homogeneous nucleation of ZnO microparticles in the solution.     

A study on the use of tactile instructions for developing robot’s motions

Developing motions for humanoid robots is time consuming. However, sport and dance instructors can easily adjust their students?? postures by simple touches. This suggests the possibility of exploiting touch for motion development, and allows us to propose a methodology based on this concept. To realize such a system, it is required to define how the robot should interpret touches. We propose a supervised learning approach to cope with this issue, and verify its feasibility experimentally. We then study the data collected by the algorithm, and show that the system is practical both for motion development and for studying human-robot tactile communication. In particular, we present considerations on the sparsity that characterize the whole process and suggest how sparsity can be exploited for efficient interpretation of tactile instructions.     

Microstructure and texture development in single layered and heterolayered PZT thin films

Single-layered Pb(Zr_0.7Ti_0.3)O₃ and Pb(Zr_0.3Ti_0.7)O₃ thin films and heterolayered Pb(Zr_1−x Ti _x )O₃ thin films consisting of alternating Pb(Zr_0.7Ti_0.3)O₃ and Pb(Zr_0.3Ti_0.7)O₃ layers were studied for their microstructure and texture development. The texture in the single-layered PZT films is affected by the Zr/Ti ratio as they have different crystallization behavior depending on the Zr/Ti ratio. With increasing film thickness, the average grain size of Pb(Zr_1−x Ti _x )O₃ increases. An unusually large grain size of 1–3 μm together with a strong (001)/(100) preferred orientation were observed for the heterolayered PZ₇₀T₃₀, whereby Pb(Zr_0.7Ti_0.3)O₃ was used as the seeding layer, for film as thin as 150 nm. The film microstructure is refined drastically when the stacking sequence is changed, i.e., when Pb(Zr_0.3Ti_0.7)O₃ is employed as the seeding layer. Thermal treatment of the PZ₇₀T₃₀ seeding layer also plays an important function in the microstructure development of the heterolayered PZ₇₀T₃₀ film. The formation of the large-grained film is correlated to the lowered nucleation energy of crystallizing Pb(Zr_0.7Ti_0.3)O₃ by the top Pb(Zr_0.3Ti_0.7)O₃. The Pb(Zr_0.3Ti_0.7)O₃ layer facilitated the nucleation and crystallization of the Pb(Zr_0.7Ti_0.3)O₃ amorphous seeding layer, whereby the overall microstructure of the heterolayered thin film was dictated by the Pb(Zr_0.7Ti_0.3)O₃ seeding layer leading to the growth of larger PZT grains.     

On the human perception of dissimilarities between postures of humanoids

This paper analyzes the perceived dissimilarity between postures of humanoid robots. First, the human perception of absolute distance between postures is focused. It is shown that results derived in computer graphics for human figures can be replicated with humanoids, despite the difference in body proportions and arrangement of the degrees of freedom. Successively, the perception of relative distances between postures is considered. It is shown that, paradoxically, better prediction of the distance between a pair of postures does not necessary lead to better predictions of which of multiple distances is the shortest. Finally, the paper concludes by briefly discussing possible implications of this finding to the fields of motion retrieval and motion blending.     

Porous Silicon Resonant Microcavity Biosensor for Matrix Metalloproteinase Detection

A real‐time, sensitive, and selective detection device to monitor the healing status of chronic wounds at the point of care is urgently required to render the management of this disease more effective. The photonic properties of porous silicon resonant microcavity (pSiRM) afford an excellent opportunity to be developed as a highly sensitive optical biosensor to monitor the presence of specific biomarkers found in the wound exudate, such as matrix metalloproteinases (MMPs). In this study, the pSiRM is designed, fabricated, and functionalized using a fluorogenic MMP peptide substrate featuring both a fluorophore and a quencher. The peptide‐functionalized pSiRM is then employed as a fluorescence‐based optical biosensor for MMPs. Active MMPs recognize and cleave the peptide sequence of the substrate, producing an immobilized peptide fragment carrying the fluorophore. The fluorescence intensity of the fluorophore embedded within the pSiRM matrix is enhanced by the photonic structure of the pSiRM compared to other pSi photonic structures. This fluorescence enhancement translates into high sensitivity, enabling detection of MMP‐1 at a limit of detection as low as 7.5 × 10^?19 m after only 15 min incubation time. Finally, the biosensor also allows the detection and quantification of the concentration of MMPs in human wound fluid.     

Ferroelectric properties of heterolayered lead zirconate titanate thin films

Heterolayered Pb(Zr_{1 − x} Ti _x )O₃ thin films consisting of alternating PbZr_0.7Ti_0.3O₃ and PbZr_0.3Ti_0.7O₃ layers were successfully deposited via a multistep sol-gel route assisted by spin-coating. These heterolayered PZT films, when annealed at a temperature in the range of 600–700^∘C show (001)/(100) preferred orientation, demonstrate desired ferroelectric and dielectric properties. The most interesting ferroelectric and dielectric properties were obtained from the six-layered PZT thin film annealed at 650^∘C, which exhibits a remanent polarization of 47.7 μC/cm² and a dielectric permittivity of 1002 at 100 Hz. Reversible polarization constituents a considerably high contribution towards the ferroelectric hysteresis of the heterolayered PZT films, as shown by studies obtained from C-V and AC measurement.