Study of lithium behaviour in Si(Li) detectors

In this paper we describe the fabrication of a conventional lithium compensated silicon detector (Si(Li)) realized on Topsil silicon with bulk resistivity 0.9 to , using the process of ion drift introduced by Pell. Preliminary results of electrical and nuclear characterization are shown. A leakage current value of 4 pA is obtained under reverse bias voltage of , at pressure of and 113 K. An alpha test using triple source ²⁴¹Am, ²³⁹Pu, ²³³U was carried and a resolution on ²⁴¹Am peak around 42 keV was obtained with this type of detector. The fabricated detector present a good electrical and nuclear characteristics that can be used in X-ray spectrometry and widespread applications in research science, environment monitoring and natural radioactivity. The main contribution of this work is the demonstration of an easy-to-implement, low cost detector set that can be achieved with an inexpensive n⁺p diode.     

High-performance solid-state supercapacitors based on graphene-ZnO hybrid nanocomposites

In this paper, we report a facile low-cost synthesis of the graphene-ZnO hybrid nanocomposites for solid-state supercapacitors. Structural analysis revealed a homogeneous distribution of ZnO nanorods that are inserted in graphene nanosheets, forming a sandwiched architecture. The material exhibited a high specific capacitance of 156 F g⁻¹ at a scan rate of 5 mV.s⁻¹. The fabricated solid-state supercapacitor device using these graphene-ZnO hybrid nanocomposites exhibits good supercapacitive performance and long-term cycle stability. The improved supercapacitance property of these materials could be ascribed to the increased conductivity of ZnO and better utilization of graphene. These results demonstrate the potential of the graphene-ZnO hybrid nanocomposites as an electrode in high-performance supercapacitors.     

A sequential process of anaerobic solid-state fermentation followed by dark fermentation for bio-hydrogen production from Chlorella sp.

Microalgal biomass has recently been one of the most widely studied feedstocks for bio-hydrogen production, owing to its richness in fermentable components, e.g. polysaccharides and proteins, and high biomass productivity. In this study, biomass of microalga Chlorella sp. TISTR 8411 was converted to hydrogen through a sequential process consisting of an anaerobic solid-state fermentation (ASSF) followed by a dark fermentation. The microalga was grown photoautothrophically in 80-L rectangular glass tanks and then scaled-up to a 240-L open pond for the production of biomass. The highest biomass concentration attained was 4.45 g L⁻¹. The biomass was harvested with over 90% flocculation efficiency at pH 11.5 and a biomass concentration of 2.6 g/L. The sequential process gave a total hydrogen yield (HY) of 16.2 mL/g-volatile-solid (VS), of which 11.6 mL/g-VS was from ASSF. The high HY obtained from the ASSF indicated that it was effective and could be integrated with a conventional hydrogen production process to improve energy recovery from biomass.     

Synthesis of <alpha>-cordierite nanoparticles from bentonite using thermal shock assisted solid-state reaction method

For the first time, we believe, nanosized <alpha>-cordierite glass-ceramics are produced using bentonite, talc, alumina, and kaolin as the raw materials and applying thermal shock to the precursor powders and sintered at 1100, 1200, and 1300?°C. A combination of a furnace at about 800?°C and liquid nitrogen was used for the applied thermal shock with a total temperature difference of about 1000?°C. The effects of thermal shock process and sintering temperature on <alpha>-cordierite formation and microstructure have been investigated. The results show that <alpha>-cordierite was formed above 1160?°C and its weight ratio increased continuously as sintered temperature increased to 1300?°C. By increasing the temperature, <alpha>-cordierite nanoparticles grain sizes and the intensity of FTIR peaks started to increase. Applying thermal shock to precursor powders reduced the grain size of each consisting mineral and resulted in nanosized <alpha>-cordierite powder.