[en] The stability and level of aggregation of nanoparticles (NPs) in physiological conditions or different media are important for biomedical applications. The interaction of NPs in different media could affect the physicochemical properties of NPs. In this study, two different sizes of amorphous silica nanoparticles (SiNPs) encapsulated dye were synthesised using the micelle entrapment method. The SiNPs encapsulated dyes suspension was mixed with different concentration of salt solution, NaCl and mouse serum and incubated at 37°C to mimic human body environment to study the interaction of SiNPs encapsulated dyes in physiological conditions. Particles agglomeration or aggregation of SiNPs encapsulated dyes in NaCl solution and mouse serum were investigated and analysed. The absorbance spectra and the stability efficacy were recorded and calculated using UV-Vis spectrometer, while the particle size was measured using Zetasizer particle analysis and transmission electron microscope (TEM). The results obtained showed that 53 nm of SiNPs was more stable compared to 30 nm both in NaCl solution and mouse serum. (paper)

[en] Praseodymium-doped Bi₄Ti₃O₁₂ (BIT) with various compositions of dopant, Pr (x = 0.5, 0.6, 0.7, 0.8) in Bi_4-xPr_xTi₃O₁₂ (BPT) were synthesized using a low temperature wet chemical technique. Powders calcined at 800 deg. C exhibit a single phase polycrystalline perovskite bismuth-layered structure. Randomly oriented plate-like structures were observed under Scanning Electron Microscope (SEM). A small amount of Pr doping (x = 0.5) resulted in dramatically reduced of grain size from 2 μm to less than 50 nm in which Pr plays the role as a grain growth inhibitor. However, by increasing the composition of Pr, bigger grain size of up to 1 μm was observed for x = 0.8 that was caused by diffusion of Pr in the perovskite structure. Dielectric properties showed that dielectric permittivity decreased with the addition of x = 0.50, and increasing with further addition of Pr. Dissipation factor (tan δ) followed the same trend as dielectric constant that was attributed to the grain size of the samples.

[en] In this work, we demonstrated a simple fabrication route towards an optically transparent and flexible memory device. The device is simple and consists of a metal/insulator/semiconductor structure; namely MIS. The preliminary MIS study with gold nanoparticles embedded between the polymethylsilsesquioxane layers was fabricated on p-Si substrate and the capacitance versus voltage measurements confirmed the charge trapped capability of the fabricated MIS memory device. Subsequently, an optically transparent and flexible MIS memory device made from indium–tin-oxide coated polyethylene terephthalate substrate and pentacene was used to replace the opaque p-Si substrate as the active layer. Current versus voltage (I–V) plot of the transparent and flexible device shows the presence of hysteresis. In an I–V plot, three distinct regions have been identified and the transport mechanisms are explained. The fabricated optically transparent and mechanically flexible MIS memory device can be programmed and erased multiple times, similar to a flash memory. Mechanical characterization to determine the robustness of the flexible memory device was also conducted but failed to establish any relationship in this preliminary work as the effect was random. Hence, more work is needed to understand the reliability of this device, especially when they are subjected to mechanical stress. - Highlights: ► An optically transparent and mechanically flexible memory is presented. ► Electrical characteristics show reprogrammable memory similar to flash memory. ► Transport mechanisms are proposed and explained. ► Mechanical bending tests are conducted

[en] High atomic number (Z) of bismuth oxide nanoparticles (Bi₂O₃ NPs) has more cell penetration and less adverse effects than conventional radiosensitisers. In this work, 60 nm and 90 nm of Bi₂O₃ NPs were successfully synthesised using the hydrothermal method by varying the bismuth nitrate, Bi(NO₃)₃ concentration. The properties of Bi₂O₃ NPs were characterised to determine the phase presence, crystallinity, morphology, elements presence and size of nanoparticles. The as-synthesised Bi₂O₃ NPs was in monoclinic Bi₂O₃ phase (ICDD 98-008-5622). As the Bi(NO₃)₃ concentration increased, the particle size of Bi₂O₃ NPs decreased due to less ions diffusion per nuclei. The morphology observation showed that Bi₂O₃ NPs were in rods form. The produced Bi₂O₃ NPs were subjected to cytotoxicity analysis and radiotherapy. Bi₂O₃ NPs did not induce cytotoxicity in breast cancer (mcf-7) cell lines at concentration from 0.05 µM. The radiotherapy performance of the as-prepared Bi₂O₃ NPs was obtained by calculating the sensitisation enhancement ratio (SER). The optimum result was found for 60 nm Bi₂O₃ NPs with SER of 3.45. (paper)

[en] The preparation procedure, structural and dielectric properties of hydrothermally derived Ba_xSr_1-xTiO₃ (BST) were studied. BST with initial Ba compositions of 75, 80, 85 and 90 mol.% were prepared by a high temperature hydrothermal synthesis. The obtained powders were pressed into pellet, cold isostatically pressed and sintered at 1200 deg. C for 3 hours. The phase compositions and lattice parameters of the as prepared powders and sintered samples were analysed using X-ray diffractometry. A fitting software was used to analyse the XRD spectra to separate different phases. It was found that BST powder produced by the high temperature hydrothermal possessed a two-phase structure. This structure became more homogeneous during sintering due to interdiffusion but a small amount of minor phase can still be traced. Samples underwent an abnormal grain growth, whereby some grains grow faster than the other due to the presence of two-phase structure. The grain size increased with increasing Ba amount. Dielectric constant and polarisation increased with increasing Ba content but it was also affected by the electronic state and grain size of the compositions