A simulation model of nitrogen transformation in reed constructed wetlands

Nitrogen has been considered as one of important elements in domestic wastewater and resulted in frequent algal blooms over a wide range of water body. In this study, a dynamic system was constructed to simulate nitrogen transformation in reed constructed wetlands. The various nitrogen forms in the system were considered as the parameters. The effects of mineralization, nitrification, denitrification, plant uptake and plant decay were investigated. The overall performance of the model was validated with different data sets of parameters from the case study spanning 3 years. The results indicated a good fit between the simulated and observed data. It appears that the model can give a reliable prediction for nitrogen removal performance in reed constructed wetland.     

Surface Chemistry Involved in Epitaxy of Graphene on 3C-SiC(111)/Si(111)

Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111) thin films on Si(111) has been studied. The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D₂-TPD) and complementarily by ex situ Raman and C1s core-level spectroscopies. The surface of the 3C-SiC(111)/Si(111) is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3)R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001) proceeds.     

Topotaxy of Corundum-Type Tetramagnesium Diniobate and Ditantalate Layers on Rock-Salt-Type Magnesium Oxide Substrates

In-plane alignments were found to occur in the product layers of corundum-type Mg₄Nb₂O₉ (MNO) and Mg₄Ta₂O₉ (MTO) on rock-salt-type MgO(001) substrates as a result of a topotaxial interface reaction between a Nb₂O₅ (or Ta₂O₅) precursor and MgO at 800°C and higher. Such alignments were attributed to a topotaxial formation of (114)-oriented MNO (or MTO) layers. This (114) orientation is hidden in the conventional XRD theta-2theta scans due to an overlap of the film (114) peak with the substrate peak, MgO(002). Its presence was revealed by XRD pole-figure measurements. The crystallographic relationship between MNO(114) [or MTO(114)] and MgO(001) is also discussed.     

Metalorganic Vapor Phase Epitaxial Growth of InAs/InGaAs Multiple Quantum Well Structures on InP Substrates

Device quality InAs/InGaAs multiple quantum well (MQW) structures were grown on InP substrates by metalorganic vapor phase epitaxy (MOVPE) and applied to lasers emitting at wavelengths longer than 2 mum. InAs/InGaAs MQWs with flat interfaces were obtained by adjusting the growth temperature between 460 degC and 510 degC. The photoluminescence peak wavelength of the MQWs increases from 1.93 to 2.47 mum as the thickness of InAs quantum wells increases from 2 to 7 nm. The structural and optical properties remained almost unchanged even after annealing at 620 degC. For 40-mu m-wide stripe broad-area lasers with 5-nm-thick InAs quantum wells, a lasing wavelength longer than 2.3 mum and an output power higher than 10 mW were achieved under continuous-wave operation at a temperature of 25 degC. These results indicate that InAs/InGaAs MQW structures grown by MOVPE are very useful for the active region of 2 mum wavelength lasers.     

Regenerative Medicine for Epilepsy: From Basic Research to Clinical Application

Epilepsy is a chronic neurological disorder, which presents with various forms of seizures. Traditional treatments, including medication using antiepileptic drugs, remain the treatment of choice for epilepsy. Recent development in surgical techniques and approaches has improved treatment outcomes. However, several epileptic patients still suffer from intractable seizures despite the advent of the multimodality of therapies. In this article, we initially provide an overview of clinical presentation of epilepsy then describe clinically relevant animal models of epilepsy. Subsequently, we discuss the concepts of regenerative medicine including cell therapy, neuroprotective agents, and electrical stimulation, which are reviewed within the context of our data.     

Contents of various sources of glucose and fructose in rice straw, a potential feedstock for ethanol production in Japan

The major carbohydrates of rice straw samples were determined in order to evaluate the potential of using rice straw as a feedstock for ethanol production in Japan. Straw samples were harvested by cutting the plants at ground level when the grain was mature and immediately heating or chilling the samples. In all cases, significant amounts (62-303 g kg⁻¹) of soft carbohydrates defined as consisting of glucose, fructose, sucrose, starch and ??-1,3-1,4-glucan were detected, in addition to structural carbohydrates (cellulose and xylan). These results indicate that rice straw is a rich source of fermentable sugars from both soft carbohydrates and lignocellulosic portions of the cell wall.     

New aspects of heterogeneous photocatalysts for water decomposition

Several new photocatalysts for overall water splitting are described. Under UV light irradiation (270 nm), La-doped NaTaO₃ modified with NiO decomposed water into H₂ and O₂ with extremely high quantum efficiency. Under an optimized condition, the apparent quantum efficiency, which was estimated with numbers of irradiated photons and evolved H₂ molecules, reached 56%. New stable photocatalytic materials containing elements with d¹⁰ electronic configuration such as In³⁺ Sn⁴⁺ and Sb⁵⁺ were developed for overall water splitting. Some mesoporous oxides were proved to be effective photocatalysts. (Oxy)nitrides of some early transition metals, i.e., Ta, Nb and Ti, were found to be stable materials having potentials for H₂ and O₂ evolutions under visible light irradiation (⪯600 nm). The electronic structures of these photocatalysts are also discussed based on DFT calculation.