Switching Transient Analysis and Characterization of an E-Mode B-Doped GaN-Capped AlGaN DH-HEMT with a Freewheeling Schottky Barrier Diode (SBD)

Journal of Electronic Materials - This paper presents a systematic study of Al0.23Ga0.77N/GaN/AlxGa1?xN double-heterojunction high-electron-mobility transistors (DH-HEMTs) with a boron-doped...     

Nano-SiO<Subscript><Emphasis Type="Bold">2</Emphasis></Subscript>: An Efficient Catalyst for the Synthesis of Some new Benzimidazoles - NMR Spectral Characterization

Some benzimidazoles were designed and synthesized by a new route using nano-SiO₂ as a highly efficient catalyst. Synthesized compounds were characterized by ¹H and ¹³C-NMR spectral studies. The significant features of this nanocatalyst are high yield of products, short reaction times, green reaction media and a vast range of substrates usage. Proton and ¹³C chemical shift of the synthesized compounds were calculated. To further confirm the compound formation single crystal XRD analysis was made and discussed for 2-(1H-benzimidazol-2-yl) phenol (1). The crystal packing features four π– π stacking interactions involving the imidazole ring, fused benzene ring and attached benzene ring system [centroid–centroid distances = 3.6106 (17), 3.6108 (17), 3.6666 (17) and 3.6668 (17) Å]. Optimization of compound 1 was performed by DFT at B3LYP/6-31G (d, p) using Gaussian-03. All these XRD data are in good agreement with the theoretical values. However, from the theoretical values it is found that most of the optimized bond lengths, bond angles and dihedral angles are slightly higher than the XRD values.     

Can-GLWS: Canadian Great Lakes Weather Service for the Soil and Water Assessment Tool (SWAT) modelling

The rapid rise in availability of large geospatial datasets for the development of hydrological models such as Soil and Water Assessment Tool (SWAT) has led to a dramatic increase in both the demand and availability of web services and tools that assist watershed modellers in incorporating data and knowledge into their modelling frameworks. Within the Canadian Great Lakes region, there is a huge potential for the application of SWAT in integrated water resources management. However, a potential barrier is the preparation of SWAT weather inputs that require time-intensive preprocessing of large data sets. Because such preprocessing is reproducible, the redundancy associated with it can be removed by introducing a web service that enables easy and open dissemination of climate data (including climate change and historical data) in SWAT-ready format. This short communication introduces such a web service called the Canadian Great Lakes Weather Data Service for SWAT (Can-GLWS). It hosts observed (historical) and projected (future) daily precipitation, daily maximum/minimum temperature, as well as weather generator database at regular grids (300 arc seconds or ~10 km) for use in SWAT simulations of the region. The novel Can-GLWS web service offers flexibility in selecting the region of interest by allowing them to be uploaded as a shapefile or to draw a rectangle or a polygon. We believe that such data as a service platform will help many practitioners to explore several issues pertaining to the sustainability of the freshwater resources of Canadian Great Lakes using the SWAT model.     

Total and organic soil carbon in cropping systems of Nepal

The significance of soil organic matter (SOM) in sustaining agriculture has long been recognized. The rate of change depends on climate, cropping system, cropping practice, and soil moisture. A 3-yr on-farm study was conducted in two major agro-ecologies (hills with warm-temperate climate and plains with subtropical climate) of Nepal. The soils in warm-temperate climate are Lithic subgroups of Ustorthents with well-drained loamy texture, and in subtropical climate are Haplaquepts with imperfectly drained loamy texture. Farmers’ predominant cropping systems were selected from different cultivation length in addition to a reference sample collected from adjacent virgin forest. The objectives were to examine the effect of cultivation length and cropping system on total carbon, KMnO₄-oxidizable soil C, C storage, and C/N ratio in two climatic scenarios: warm-temperate and subtropical. A large difference in KMnO₄-oxidizable soil organic C was observed due to the effect of cultivation length and cropping system. However, TC remained similar during the 3-year study. The decrease in KMnO₄-oxidizable C due to cultivation was more in the surface layer (43–56%) than in the subsurface layer (20–30%). Total C in uncultivated, < 10-year cultivated, and > 50-year cultivated soil was 22, 13, and 10 g kg⁻¹ in warm-temperate climate and 10, 6, and 5 g kg⁻¹ in subtropical climate, respectively. During the 3-year study period in both climates, large changes in soil C were observed for KMnO₄-oxidizable C but not for TC, confirming our earlier work on the usefulness of the KMnO₄ oxidized fraction for detecting a relatively short-term increase or decrease in soil C pool. The TC storage in uncultivated, < 10-year cultivated, and > 50-year cultivated soil was 38, 25, and 19 Mg ha⁻¹ in warm-temperate climate and 22, 15, and 12 Mg ha⁻¹ in subtropical climate, respectively. The rice–wheat and maize–potato cropping systems were good in storing soil C of 30 and 20 Mg ha⁻¹ for 0–15-cm soil depth in warm-temperate climate. The rice–wheat cropping system was also good in storing soil C in subtropical climate (19 Mg ha⁻¹) compared with other cropping systems studied.     

Preparation and hydration of β-C2S without stabilizer

The preparation method of β-C ₂S without stabilizer, and their hydration characteristics were studied. β-C₂S is formed when γ-C₂S is heated at about 1000°C or about 1500°C. The hydration kinetics of β-C₂S produced from α′-C₂S is markedly different from that from α-phase. Ca(OH)₂ is hardly produced in the hydration of β-C₂S without stabilizer. Formed C-S-H has a composition of $\text{C/S}\text{? 2}$.     

氧气体积分数对气调保鲜猪肉品质的影响

将从无锡当地市场购买的新鲜猪肉装入每盒分别含5％，15％，25％，35％，45％，55％的O2与20％的CO2的包装盒内，在4℃下储存8d。测定样品中的TVBN值，TBARs值，颜色分值，感官评定值和微生物总数，结果表明：猪肉气调保鲜时氧气的较好配比为45％和55％，然而，TBARs值在45％O2时比在55％O2时要低。因此，45％O2和20％CO2气体混合物可作为最适宜的组合气体来包装新鲜猪肉。     

The effect of post-treatment of a high-velocity oxy-fuel Ni-Cr-Mo-Si-B coating Part I: Microstructure/corrosion behavior relationships

The microstructure and aqueous corrosion characteristics of a Ni-Cr-Mo-Si-B high-velocity oxy-fuel (HVOF) coating have been assessed. It has been shown that postprocessing by vacuum fusion has a significant effect on the coating microstructure by increasing the type and concentration of hard phase particles. The principal hard phases in the as-sprayed condition and vacuum-sealed condition are chromium carbides, whereas molybdenum-containing boride phases are also present after vacuum fusion. Vacuumfusion post-treatment eliminates splat boundaries, which can act as sites, where preferential corrosion can occur and, hence, the dominant corrosion mechanisms change. In as-sprayed and vacuum-sealed coatings, localized attack at splat particle boundaries and crevice corrosion dominate, whereas in vacuum-fused coating, the principal mechanism of corrosion is “micropitting” as a result of the hard phase loss.     

Dynamics of Population Ageing in Nepal and the Need for Action

Over the past decades, the problem of ageing has grown steadily in Nepal. The demographic measures obtained from different population censuses of Nepal amply demonstrate this. In this context, the present study attempts to analyze population census 2011 data to assess elderly population across the nation by area types, eco-belts, development regions and by gender perspective through computation of major population ageing indicators for these cross-sectional areas of Nepal. The analysis showed that the indicators like median age, proportion of elderly population, elderly dependency ratio and life expectancy at birth have increased significantly in 2011 census compared to 2001 census stressing the need of appropriate actions for the management, welfare and care of elderly people in Nepal. Even though population ageing is found more evident in urban areas regarding median age and index of ageing, percent elderly population aged 60 and above and elderly dependency are actually higher in rural areas which can be attributed to more out-migration of young people in rural areas. Eco-belt-wise, elderly dependency is found higher in mountain but other ageing indicators are at higher levels in hills. Development region-wise, western region shows relatively more ageing stress compared to other regions except that median age is found highest in the central region. Additionally, two semi-log statistical models that fit well are also built to associate percent elderly populations of Nepal with crude birth rate based upon population censuses of Nepal.     

Coverage and connectivity aware energy efficient scheduling in target based wireless sensor networks: an improved genetic algorithm based approach

Wireless Networks - Energy efficient scheduling of sensor nodes is one of the most efficient techniques to extend the lifetime of the wireless sensor networks (WSNs). Instead of activating all the...     

Characterization of reduced graphene oxide obtained from vacuum-assisted low-temperature exfoliated graphite

Microsystem Technologies - Graphene consists of sheets of two-dimensional allotrope carbons and is a basic element of graphite. Herein, reduced graphene oxide (rGO) were exfoliated from graphite...