MoO3 nanoplates reinforced the structural, electrical, mechanical, and antibacterial characteristics of polyvinyl pyrrolidone/sodium alginate polymer blend for optoelectronics and biological applications.

Organic/Inorganic nanostructures enable the development of new functional materials for optoelectronics and biological applications. In this work, nanocomposite films of polyvinyl pyrrolidone (PVP) and sodium alginate (NaAlg) blend matrix (30/70 wt%) filled with molybdenum trioxide (MoO3) nanoplates were prepared using solution casting procedure. The effect of MoO3 nanoplates on structural, optical, electrical and antibacterial characteristics of pure PVP/NaAlg blend was investigated. The sizes of MoO3 nanoplates had dimensions between 90 and 420 nm with orthorhombic phase as indicated by the TEM and XRD techniques. Also, the XRD patterns of filled films suggested that the presence of crystalline phases of MoO3 within PVP/NaAlg matrix. FTIR analysis revealed the primary vibrational peaks of PVP and NaAlg, whose strength altered randomly after filling. The UV absorption increased gradually and shifted to the higher wavelength side. The alternating current (AC) conductivity and dielectric parameters were improved with increasing MoO3 concentration. The antibacterial activity against Staphylococcus aureus and Escherichia coli increased with increase of MoO3 nanoplates concentration. The filled PVP/NaAlg-MoO3 samples displayed considerable enhancements in the values of Young's modulus (Y), tensile stress (σt) and elongation at break (εB). The obtained results imply that these nanocomposite films can be potentially used in optoelectronics and biological applications.

Realistic risk assessment of arsenic in rice.

Over 3 billion people share a diet consisting mainly of rice, which may contain significant amounts of arsenic. Because the toxicity of arsenic is dependent on its chemical form and that it may be in a form that is not bio-accessible (i.e. dissolved in the gastrointestinal tract) and can thus not become bio-available (i.e. end up in the blood stream, where it may exert its toxic effect), the bio-accessibility of arsenic was determined in thirteen different types of rice. The effects of washing and cooking were also studied. The total concentration of arsenic ranged from 93 to 989 µg kg-1 and its bio-accessibility ranged from 16 to 93%. Cooking only changed arsenic speciation in a few cases. However, simply washing rice with arsenic-free water before cooking removed 3-43% of the arsenic, resulting in all the rice tested except the most contaminated one being safe to consume by adults.