New Insight into Procedure of Interface Electron Transfer through Cascade System with Enhanced Photocatalytic Activity

Recombination of photogenerated electron–hole pairs is extremely limited in the practical application of photocatalysis toward solving the energy crisis and environmental pollution. A rational design of the cascade system (i.e., rGO/Bi₂WO₆/Au, and ternary composites) with highly efficient charge carrier separation is successfully constructed. As expected, the integrated system (rGO/Bi₂WO₆/Au) shows enhanced photocatalytic activity compared to bare Bi₂WO₆ and other binary composites, and it is proved in multiple electron transfer (MET) behavior, namely a cooperative electron transfer (ET) cascade effect. Simultaneously, UV–vis/scanning electrochemical microscopy is used to directly identify MET kinetic information through an in situ probe scanning technique, where the “fast” and “slow” heterogeneous ET rate constants (K_eff) of corresponding photocatalysts on the different interfaces are found, which further reveals that the MET behavior is the prime source for enhanced photocatalytic activity. This work not only offers a new insight to study catalytic performance during photocatalysis and electrocatalysis systems, but also opens up a new avenue to design highly efficient catalysts in photocatalytic CO₂ conversion to useful chemicals and photovoltaic devices.     

Novel wet-chemical synthesis and characterization of nanocrystalline CeO2 and Ce0.8Gd0.2O1.9 as solid electrolyte for intermediate temperature solid oxide fuel cell (IT-SOFC) applications

Novel wet-chemical methods of synthesis have been adopted to synthesize nano-crystalline CeO₂ and Gd-substituted compositions aiming to explore an efficient oxide ion conducting solid electrolyte for intermediate temperature solid oxide fuel cell (IT-SOFC) applications. Nano-crystalline CeO₂ powders were synthesized by combustion method using redox mixture of cerric ammonium nitrate or cerium nitrate and maleic acid or 1,3-dimethylurea and compared with high surface area CeO₂ powders prepared by hydrothermal technique with microwave precipitated precursor from aqueous solutions of (NH₄)₂Ce(NO₃)₆ and urea. The grain size achieved by the hydrothermal technique is ∼7 nm which is smaller than that of commercial nano CeO₂ powders. Conventional or microwave sintering was used to prepare dense Ce_0.8Gd_0.2O_1.9 pellets from the ceria powders made of redox mixture of cerium nitrate, 1,3-dimethylurea (DMU) and Gd₂O₃ as the starting ingredients. The samples were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and ac impedance spectroscopy. The ionic conductivity measured for the pellet sintered at 1400 °C is 1 × 10⁻² and 2.4 × 10⁻² S/cm at 700 °C and 800 °C respectively.     

Samarium Ion-Doped Maghemite Nanoparticles: Synthesis,Microstructural, Optical,and Magnetic Characterizations

Journal of Superconductivity and Novel Magnetism - This paper reports the effects of rare-earth Sm3+ ion substitution on structural, optical, electronic, and magnetic responses of maghemite...     

An intelligent instrument for tracking and adaptive filtering of oscillatory signals using Hebbian learning rules

In this paper Hebbian type of learning algorithms using total least squares method is applied for adaptive filtering techniques to remove the noise and undesired oscillatory signals at different systems. Here we have used the generalised Hebbian learning rules for initializing the internal representations of a feedforward neural network, which accelerates the convergence of supervised Hebbian learning rule. In case of constrained anti-Hebbian learning rule, the weight vectors of linear neuron unit is converged to an eigenvector which has the smallest eigenvalue. In the total least squares (TLS) method the noise rejection capability is superior to the least squares method. Here we have applied the initial sets of data for the internal representation of feedforward network which consists of bottom-up unsupervised learning process followed by top-down supervised learning process using total least squares (TLS) algorithm. For faster convergence we have included the momentum term for the updating of weights. An intelligent instrumentation scheme has been developed for on-line measurement of amplitude of oscillatory signals. The undesired oscillations of the signal is also removed by implementing neural network model (using Hebbian rules and total least square algorithm) on a digital signal processor.     

Compositing and Storage of Air and Wastewater Samples

The performance of a field study to determine whether any of the 14 New York City water pollution control plants are major sources of air pollution required sampling and the analysis of a large number of samples. To reduce the number of samples for analysis and address the associated storage concerns of the analytical laboratories, the experimental design called for compositing air and wastewater samples, and for investigating the stability of wastewater samples. This paper addresses the quality control issues associated with the compositing and stability components of the experimental design. The study tested the hypothesis that compositing techniques used for air and wastewater sampling lead to results that are not unlike those obtained by conventional grab sampling. The study also tested whether wastewater samples stored under proper laboratory conditions remain stable for a period longer than the conventionally accepted storage period of 2 weeks. Statistical analyses demonstrated that the hypotheses tested cannot be rejected and, consequently, compositing techniques employed in this study are equivalent to conventional grab sampling and the storage period of samples can be extended beyond the accepted 2 week period.     

Biogenic Collagen-Nano ZnO Composite Membrane as Potential Wound Dressing Material: Structural Characterization,Antibacterial Studies and In Vivo Wound Healing Studies

Journal of Inorganic and Organometallic Polymers and Materials - The practical applicability of collagen, a natural polymer, as a wound dressing material is hindered due to its reduced stability...     

Influence of magnetic ion doping on structural,optical, magnetic and hyperfine properties of nanocrystalline SnO<Subscript>2</Subscript> based dilute magnetic semiconductors

This article reports the structural, optical and magnetic properties of transition metal (Ni, Co, Mn and Fe) doped SnO₂ nanoparticles prepared by modified Pechini sol–gel method. From the X-ray diffraction studies, it is obvious that all the synthesized samples show a phase purity of rutile tetragonal crystal structure of SnO₂. The morphology was studied and the particle sizes were estimated from the field emission scanning electron microscopy. From photoluminescence spectra, we observed emission due to the presence of singly ionized oxygen vacancies. Raman spectroscopy shows dominant peaks at 644 and 782 cm^?1 which were ascribed to A_1g and B_2g modes of the rutile structure. Isomer shifting due to dopant addition and large quadrupole splitting due to surface defects were observed in Mössbauer spectra. All the samples show ferromagnetic ordering up to 1 T. The relatively stronger ferromagnetic nature in Fe and Co doped SnO₂ is due to the strong p–d exchange interaction. In case of Ni and Mn doped SnO₂ samples, the lack of carrier-mediated interaction due to its inherent semiconducting nature reduces the total magnetic moment observed in these samples. The exchange coupling depends on the dopant type and its concentration.     

Home-grown school feeding: promoting local production systems diversification through nutrition sensitive agriculture

The consumption of some non-staple crops such as legumes and dark, green leafy vegetables can address common deficiencies in key nutrients such as vitamin A and iron; however, limited markets and supply chain development impede their production and accessibility to consumers. This study investigates the pathways to promote agricultural production and dietary diversity for a local market intervention called Home-Grown School Feeding (HGSF). School feeding menus from 24 districts across 10 regions in Ghana during the 2014–15 school year were analysed in terms of food groups and several individual foods. The menus were then compared with food groups produced by households during the past year or consumed in the past seven days using data collected from a household survey. Greater inter-food group diversity in the menus was associated with higher production levels for tubers and dark, leafy green vegetables in the South and cereals in the North. A correspondence between the frequency in which a food group appeared in a menu and the share of households who consumed foods from the food group was also noted. Key issues, such as optimizing supply chains, enabling farm linkages and supporting diverse nutrient rich food groups, that underlie the success of Home-Grown School Feeding and other agricultural policies with similar goals of promoting production and dietary diversity are highlighted through commodity specific examples. The findings of this study may help strengthen operational linkages between agriculture production and nutrition for HGSF and other similar interventions.