In this review the interaction between femtosecond laser and matter with emphasis on silicon and some metals have been appraised. For silicon, spikes are produced as a result of interaction in the presence of background gas such as SF 6 , or H 2 S with an appropriate background pressure, but spikes are not formed in the presence N 2 or air. The formation of the spikes increase the infrared light absorption of silicon to near unity. Interaction of femtosecond laser with metals form periodic surface structures that make the metals exhibit many different morphological characteristics. This processing technique allows the creation of a variety of colors on a metal that ultimately lead to control of its optical properties from UV to terahertz. From the assessment made, the potential of femtosecond laser structuring of materials for cost-effective nano-manufacturing is high.
For about three decades, DNA-based nanotechnology has been undergoing development as an assembly method for nanostructured materials. The DNA origami method pioneered by Rothemund paved the way for the formation of 3D structures using DNA self assembly. The origami approach uses a long scaffold strand as the input for the self assembly of a few hundred staple strands into desired shapes. Herein, we present a 3D origami "roller" (75 nm in length) designed using caDNAno software. This has the potential to be used as a template to assemble nanoparticles into different pre-defined shapes. The "roller" was characterized with agarose gel electrophoresis, atomic force microscopy (AFM) and transmission electron microscopy (TEM). DNA nanotechnology uses the molecular recognition properties of DNA to create artificial DNA structures for specific technological purposes. This branch of nanotechnology holds great promise for a vast range of applications in fields such as medicine, materials science, biology and biochemistry. The theoretical framework for using DNA as a building material for the construction of nanoscale devices was laid down by Seeman [1,2]. This is made possible due to DNA's capacity for programmable self-assembly and its high stability. In subsequent works, several authors have used DNA to construct an increasing number of composite structures [3][4][5][6][7][8][9]. After the potential of DNA self-assembly was well established, Rothemund [10] introduced the method of DNA origami which is versatile in constructing pre-defined designs. The process involves heating a mixture of scaffold and staple strands to several degrees Celsius and annealing at room temperature for several hours to yield single-layered structures. For multilayered structures, several days are needed for folding [11,12]. This simple, "one-pot" method uses several hundred staple strands to direct the folding of a long, single scaffold strand of DNA into pre-defined shapes [10]. Applications have emerged based on DNA origami, such as using it to arrange metal nanoparticles [13][14][15], to design and construct detergent-resistant liquid crystal DNA-nanotubes that can in turn be used to induce weak alignment of membrane proteins [16], to produce label-free RNA hybridization probes [17], and for the self-assembly of carbon nanotubes into two-dimensional geometries [18].Here, we describe the design of a 3D origami structure, which resembles a roller, using the open source software package, caDNAno, constrained to the honeycomb framework [12]. We analyze and characterize the structure obtained using gel electrophoresis, atomic force microscopy (AFM) and transmission electron microscopy (TEM). Our "roller" design has the potential to be used to arrange nanoparticles into a range of different shapes.
Alumina ceramic coating was prepared on Q235 carbon steel by plasma electrolytic oxidation. The discharge process was analysed according to the voltage-time curve. The microstructure of the ceramic coating was investigated by scanning electron microscopy, X-ray diffractometry and energy dispersive X-ray spectroscopy. The bonding strength, thickness, hardness, surface roughness and corrosion properties of the coatings were studied. The results indicated that coating on Q235 carbon steel mainly consisted of a-Al 2 O 3 and c-A1 2 O 3 . The coating showed coarse and porous surface. The surface roughness of the coating was 1?8 mm, and the average diameter of the pores was 3-4 mm. The hardness of the coating was 1854 HV. The thickness of the coating was ,28 mm, and the bonding strength was 23 MPa. The corrosion tests indicated that the corrosion current density of alumina coated Q235 in 3?5%NaCl was 8?289610 27 A cm 22 , which was decreased by two orders of magnitude compared with the uncoated one. The corrosion potential was increased to 20?379 V, which shifted positively by 0?303 V compared to the uncoated one.
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