Metal and metal oxide nanoparticle synthesis from metal organic frameworks (MOFs): finding the border of metal and metal oxides

Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co(3)O(4), ZnO, Mn(2)O(3), MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N(2), whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N(2). Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N(2) and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H(2) and CO(2) adsorption properties depending on the environment used for the thermolysis of MOFs.     

Recent progress and future aspects of organic solar cells

This article aims to review the recent progress and future aspects of organic solar cells (OSCs). Different device designs proposed for efficient light harvesting and their advancements have been discussed. We have discussed various parameters limiting their efficiency and their possible solutions. Special attention has been paid to understand the device physics and its fundamental facets. Open circuit voltage (V_oc) is an important parameter in the determination of their efficiency, but the picture behind the real origin of V_oc is not very much clear; therefore, this issue has been discussed in detail. Short lifetime is another important issue; therefore, recent progress in stability and related issues has also been discussed. The progress in roll to roll (R2R) processing and demonstration for large‐area OSCs has been paid particular attention. The areas, where further advances will help in the commercial realization of this technology, have also been discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

A novel method for pesticide analysis in refined sugar samples using a gas chromatography–mass spectrometer (GC–MS/MS) and simple solvent extraction method

A sensitive method for the quantification of 11 pesticides in sugar samples to the μg kg⁻¹ level has been developed. These pesticides are often used in an agricultural context. A simple solvent extraction followed by selective analysis using a gas chromatography–mass spectrometric method was used. This method was accurate (?99%) as it possesses limits of detection in the 0.1-μg kg⁻¹ range, and the coefficients of variations are less than 15% at the low μg kg⁻¹ end of the method’s linear range. The percent recovery of all the pesticides at the lowest levels of detection ranges from 82% to 104%. This method was used for the quantification of pesticides in sugar samples collected from different factory outlets from different parts of India. In this study, 27 refined sugar samples were analysed in which one sample showed a detectable level of the chlorpyrifos pesticide. This study showed that Indian sugar is free from the commonly-used pesticides at the low μg kg⁻¹ levels.     

Modelling the impacts of bioenergy markets on the forest industry in the southern United States

The main objective of this article was to analyse the impacts of emerging bioenergy markets on traditional forest product sector markets in the USA. An econometric model was developed to obtain the equilibrium estimates for the bioenergy and traditional forest markets. The results from the econometric model, using data-set for the state of Florida, suggested that biomass for bioenergy and pulpwood and biomass for bioenergy and sawtimber act as substitutes while sawtimber and pulpwood act as complements to each other. A price subsidy policy scenario was considered to simulate a 30% increase in the demand for biomass for bioenergy. The simulation results suggested that inclusion of this policy scenario might generate additional benefits to forest landowners and bioenergy sector, while sawmill and pulpmill sectors might face adverse financial impacts.     

Colour Measurement and Analysis in Fresh and Processed Foods: A Review

Colour is an important quality attribute in the food and bioprocess industries, and it influences consumer’s choice and preferences. Food colour is governed by the chemical, biochemical, microbial and physical changes which occur during growth, maturation, postharvest handling and processing. Colour measurement of food products has been used as an indirect measure of other quality attributes such as flavour and contents of pigments because it is simpler, faster and correlates well with other physicochemical properties. This review discusses the techniques and procedures for the measurement and analysis of colour in food and other biomaterial materials. It focuses on the instrumental (objective) and visual (subjective) measurements for quantifying colour attributes and highlights the range of primary and derived objective colour indices used to characterise the maturity and quality of a wide range of food products and beverages. Different approaches applied to model food colour are described, including reaction mechanisms, response surface methodology and others based on probabilistic and non-isothermal kinetics. Colour is one of the most widely measured product quality attributes in postharvest handling and in the food processing research and industry. Apart from differences in instrumentation, colour measurements are often reported based on different colour indices even for the same product, making it difficult to compare results in the literature. There is a need for standardisation to improve the traceability and transferability of measurements. The correlation between colour and other sensory quality attributes is well established, but future prospects exist in the application of objective non-destructive colour measurement in predictive modelling of the nutritional quality of fresh and processed food products.     

Kikuchi rings from polycrystalline platinum films with a 〈111〉 fiber axis

Platinum films were grown on mica substrates in ultrahigh vacuum. These films have a strong 〈111〉 fiber axis orientation as found by low energy electron diffraction, reflection high energy electron diffraction and transmission electron diffraction studies. A new form of Kikuchi pattern, namely Kikuchi rings, was found in the diffraction pattern of these oriented polycrystalline films. This is the first time that a Kikuchi pattern has been reported from a polycrystalline film with a fiber axis.     

Wavelength requirements of all-optical networks

All-optical networks are networks for which all data paths remain optical from input to output. With rapid development of optical technology, such networks are a viable choice for the high speed wide area networks of the future. Wavelength division multiple access (WDMA) currently provides the most mature technology for all-optical networks. The authors discuss a class of WDMA networks that are homogeneous in the sense that each node contains both an input/output port and a switch. They focus on the permutation routing problem and first, present a lower bound on the number of wavelengths required for permutation routing as a function of the size and degree of the network. They use particular topologies, including the multistage perfect shuffle, the Debruijn, and the hypercube, to find achievable upper bounds on the number of required wavelengths     

Capillary electrophoresis chips with a sheath-flow supported electrochemical detection system

Microfabricated capillary electrophoresis chips containing an integrated sheath-flow electrochemical detector are developed with the goal of minimizing the influence of separation voltages on end-column detection while maintaining optimum performance. The microdevice consists of an upper glass wafer carrying the etched separation, injection, and sheath-flow channels and a lower glass wafer on which gold- and silver-plated electrodes have been fabricated. The sheath-flow channels join the end of the separation channel from each side, and gravity-driven flow carries the analytes to the electrochemical detector placed at working distances of 100, 150, 200, and 250 microm from the separation channel exit. The performance of this detector is evaluated using catechol and a detection limit of 4.1 microM obtained at a working distance of 250 microm. Detection of DNA restriction fragments and PCR product sizing is demonstrated using the electroactive intercalating dye, iron phenanthroline. Additionally, an allele-specific, PCR-based single-nucleotide polymorphism typing assay for the C282Y substitution diagnostic for hereditary hemochromatosis is developed and evaluated using ferrocene-labeled primers. This study advances the feasibility of high-speed, high-throughput chemical and genetic analysis using microchip electrochemical detection.     

Towards modelling of a trabecular bone

Trabecular bone (lightweight spongy bone) comprises of a complex arrangement of plates and struts at micro level that make it anisotropic. Osteoporosity (leading to fracture) is a common problem in old age which makes the bone weak due to increased porosity. Considerable two dimensional data in the form of images is available on the porous structure of the bone, however this needs to be related to the macro-level anisotropic properties. This preliminary study aims to examine whether topological anisotropy can be related to elastic anisotropy. Simple three dimensional structured meshes comprising of elements with different material properties are used to simulate the porous structure. Homogenised elastic properties are evaluated and these are compared with a two dimensional topology anisotropy indicators. For the simple problems considered it appears that topological anisotropy cannot be directly linked to elastic anisotropy.     

Electrical,rheological, and mechanical properties copolymer/carbon black composites

This work aims to evaluate the electrical conductivity and the rheological and mechanical properties of copolymer/carbon black (CB) conductive polymer composites (CPCs). The copolymers, containing ethylene groups in their structure, used as matrix were polyethylene grafted with maleic anhydride (PEgMA), ethylene-methyl acrylate–glycidyl methacrylate (EMA-GMA), and ethylene-vinyl acetate (EVA). For comparison purposes, bio-based polyethylene (BioPE)/CB composites were also studied. The electrical conductivity results showed that the electrical percolation threshold of BioPE/CB composite was 0.36 volume fraction of CB, whereas the rheological percolation threshold was 0.25 volume fraction of CB. The most conductive CPC was BioPE/CB. Among the copolymer/CB CPCs, PEgMA/CB showed the highest conductivity, which can be attributed to the fact that the PEgMA copolymer had higher crystallinity. It also has a higher amount of ethylene groups in its structure. Torque rheometry analysis indicated that EMA-GMA copolymer may have reacted with CB. Rheological measurements under oscillatory shear flow indicated the formation of a percolated network in BioPE/CB and copolymer/CB composites. Morphology analysis by scanning electron microscopy (SEM) indicated the formation of a percolated network structure in BioPE/CB composite and finely dispersed CB particles within the PEgMA copolymer. Wetting of CB particles/agglomerates by the copolymer matrix was observed in EVA/CB and EMA-GMA/CB composites. Conductive CB acted as reinforcing filler as it increased the elastic modulus and tensile strength of BioPE and the copolymers.