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The design of hydroxyapatite (HA) nanoarchitecture is critical for fabricating artificial bone tissues as it dictates the biochemical and the mechanical properties of the final product. Herein, we incorporated a simple hard-template approach to synthesise single crystal nanoplates of HA. We used the 2D graphitic nitride (g-C 3 N 4 ) material to prepare an HA sol-gel under hydrothermal conditions. A new HA nanostructure was then formed during the calcination and removal of g-C 3 N 4 at a higher temperature, which finally led to the production of nanoplates (thickness of ∼100 nm) while in lateral dimension the average size was in the micrometre scale. We characterised the synthesised HA nanoplates with XRD, TEM, and HRTEM. The theoretically predicted nanostructure construction based on Wulff's method is in full agreement with the experimental observations. We then prepared different weight ratios of HA and polylactic acid (PLA) composites for artificial 3D bone fabrication. The strong interaction between PLA and HA's (110) facet, which was the second most prevalent, resulted in the composite's mechanical robustness. After mechanical testing, an optimum ratio was selected for biological studies and 3D printing. Biological experiments demonstrated that the synthesised composite had excellent viability in vitro.

We report the first observation of the electronic level scheme in boron (B)- and phosphorus (P)-doped nanowires (NWs). The NWs' morphology dramatically depends on the doping impurity while a few deep electronic levels appear in both kinds of nanowires, independently of the doping type. We demonstrate that the doping impurities induce the same shallow levels as in bulk silicon. The presence of two donor levels in the lower half-bandgap is also revealed. In both kinds of NWs, B- and P-doped, the donor level (0/+) at E(v) + 0.36 eV of the gold-hydrogen complex is observed. This means that the gold diffusion from the NW tip introduces an electronically active level, which might negatively affects the electrical characteristics of the NWs. In P-doped NWs, we observed a further donor level at 0.26 eV above the valence band due to the phosphorus-vacancy pairs, the E-center, well-known in bulk silicon. These findings seriously question both diffusion modeling of impurities in NWs and the technological aspects arising from this.

Gaining an understanding the dynamic behaviors of dopant atoms in silicon nanowires (SiNWs) is the key to achieving low-power and high-speed transistor devices using SiNWs. The segregation behavior of boron (B) and phosphorus (P) atoms in B- and P-doped SiNWs during thermal oxidation was closely observed using B local vibrational peaks and Fano broadening in optical phonon peaks of B-doped SiNWs by micro-Raman scattering. Electron spin resonance (ESR) signals from conduction electrons were used for P-doped SiNWs. Our results showed that B atoms preferentially segregate in the surface oxide layer, whereas P atoms tend to accumulate in the Si region around the interface of SiNWs. The radial distribution of P atoms in SiNWs was also investigated to prove the difference segregation behaviors between of P and B atoms.

Abstract: This study deals with the use of laser techniques for preparation of advanced Ag nanostructure on quartz substrates that can be applied in high‐resolution analyses, namely, surface enhanced Raman spectroscopy (SERS). The active system was a two dimensional array of nanoparticles produced by laser annealing of thin silver film. The optical and morphological properties of the nanostructure were compared with those of an as deposited thin film in order to estimate their role in the detection efficiency. The activity of the structures fabricated as substrates for SERS of usually applied in agricultural medicine small quantities of Aktara 25 BG (thiamethoxam) insecticide was tested. To the best of our knowledge, SERS spectra of Aktara 25 BG are presented for the first time. The minimum detected concentration of thiamethoxam was evaluated to be in the order of μg/ml. The simple fabrication method and demonstrated efficiency focus the presented study to direct bearing on the human health and food quality area as a way of assisting the detection of small amounts or residue of harmful pollutants. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen passivation of phosphorus (P) donors and defects in P-doped silicon nanowires (SiNWs) were investigated by electron spin resonance (ESR) at 4.2K. P doping was performed during the synthesis of SiNWs by laser ablation. Phosphorus doping into substitutional sites of crystalline Si in SiNWs was demonstrated by detection of an ESR signal with a g-value of 1.998, which corresponds to conduction electrons in crystalline Si. ESR signals related to defects in surface oxide layer and at interface between surface oxide and crystalline Si core were observed. These P donors and the defects were partially passivated by hydrogen and oxygen atoms as seen in bulk Si. [Copyright &y& Elsevier]