Niobium oxide as support material for the oxidative dehydrogenation of propane

The ability of using niobium oxide (Nb₂O₅) as a support for preparing surface metal oxide species and testing the catalyst for the ODH of propane was done in the present study. Chromium oxide was used as the representative surface metal oxide species. To test the objective several loadings of Cr₂O₃/Nb₂O₅ were prepared by the incipient wetness impregnation technique. Surface area analysis, Raman, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy and TPR studies were used to characterize the sample. It was observed that surface chromium oxide species are formed similar to those on other oxide supports and similar monolayer coverages were achieved. However, the reduction characteristic (T_max temperature) was different due to the change in the Cr–O–support bond. The ODH of propane over the Cr₂O₃/Nb₂O₅ catalysts revealed that the activity increased up to monolayer coverage and then decreased due to the presence of Cr₂O₃ crystals. Similar observations were seen for the V₂O₅/Nb₂O₅ and MoO₃/Nb₂O₅ catalysts. The turnover frequency (TOF) was independent of coverage for the surface chromium, vanadium and molybdenum oxide species on Nb₂O₅. The constant TOF suggests the structure insensitivity of this type of reaction. The propene selectivities were high and relatively constant for the Cr₂O₃/Nb₂O₅ catalysts revealing the higher yields that can be obtained on this series of catalysts compared to the Cr₂O₃/Al₂O₃ and Cr₂O₃/TiO₂ catalysts. Additional studies involving tungsten and molybdenum oxide additives on 1% Cr₂O₃/Nb₂O₅ reveal the effect of exposed support surface on the propene selectivities.     

Effect of Size Parameters of Mix Ingredients on the Porosity and Reduction Characteristics of Sinter

The paper aims to describe the effect of size parameters of the mix ingredients on the tumbler index, porosity and reduction properties of sinter. These parameters are important factors for the furnace performance when the sinter is fed as burden material Understandably, the fines generated inside the furnace in the stack zone or during reduction affect the permeability of the stack zone, which results in a decrease in driving rate and CO utilisation. Pot sintering studies were carried out using hematite ore mix from typical mines in India. The sinter basicity (CaO/SiO₂) and MgO content in the sinter were kept at 2.1 and 1.5% respectively. The effect of the size parameters of the mix ingredients, namely size of coke, size of ore fines and that of limestone, on the porosity and quality parameters of sinter was investigated. The studies have shown that reducibility of sinter was well correlated with the proportion of micro‐pores out of total pores available in the sinter. Micro‐porosity of the sinter samples and their reducibility increased with decrease in the size range of coke breeze. Sintering of ore fines with reduced size, also, increased the sinter micro‐porosity. Besides, the average pore radius and density of the sinter sample and consequently the sinter reducibility increased with decreasing ore size. When the size of flux was narrowed down to –3+0.5 mm from –3 mm, the reduction degradation index value declined from 26.8% to 25.6% with marginal decrease in sinter reducibility. Moreover, the speed of sintering increased as well.     

Genetically engineered protein in hydrogels tailors stimuli-responsive characteristics

Certain proteins undergo a substantial conformational change in response to a given stimulus. This conformational change can manifest in different manners and result in an actuation, that is, catalytic or signalling event, movement, interaction with other proteins, and so on. In all cases, the sensing-actuation process of proteins is initiated by a recognition event that translates into a mechanical action. Thus, proteins are ideal components for designing new nanomaterials that are intelligent and can perform desired mechanical actions in response to target stimuli. A number of approaches have been undertaken to mimic nature's sensing-actuating process. We now report a new hybrid material that integrates genetically engineered proteins within hydrogels capable of producing a stimulus-responsive action mechanism. The mechanical effect is a result of an induced conformational change and binding affinities of the protein in response to a stimulus. The stimuli-responsive hydrogel exhibits three specific swelling stages in response to various ligands offering additional fine-tuned control over a conventional two-stage swelling hydrogel. The newly prepared material was used in the sensing, and subsequent gating and transport of biomolecules across a polymer network, demonstrating its potential application in microfluidics and miniaturized drug-delivery systems.     

TRAPPY: a truthfulness and reliability aware application placement policy in fog computing

The Journal of Supercomputing - Fog computing facilitates the satisfaction of Internet of things (IoT) users by running time-sensitive offloaded applications. Heterogeneity, dynamism, and the...     

Molecular Aptamer Beacons and Their Applications in Sensing,Imaging, and Diagnostics

The ability to monitor types, concentrations, and activities of different biomolecules is essential to obtain information about the molecular processes within cells. Successful monitoring requires a sensitive and selective tool that can respond to these molecular changes. Molecular aptamer beacon (MAB) is a molecular imaging and detection tool that enables visualization of small or large molecules by combining the selectivity and sensitivity of molecular beacon and aptamer technologies. MAB design leverages structure switching and specific recognition to yield an optical on/off switch in the presence of the target. Various donor–quencher pairs such as fluorescent dyes, quantum dots, carbon‐based materials, and metallic nanoparticles have been employed in the design of MABs. In this work, the diverse biomedical applications of MAB technology are focused on. Different conjugation strategies for the energy donor–acceptor pairs are addressed, and the overall sensitivities of each detection system are discussed. The future potential of this technology in the fields of biomedical research and diagnostics is also highlighted.     

Maximizing availability for task scheduling in computational grid using genetic algorithm

Computational grid provides a wide distributed platform for high‐end compute intensive applications. Grid scheduling is often carried out to schedule the submitted jobs on the nodes of the grid so that some characteristic parameter is optimized. Availability of the computational nodes is one of the important characteristic parameters and measures the probability of the node availability for job execution. This paper addresses the availability of the grid computational nodes for the job execution and proposes a model to maximize it. As such, the task scheduling problem in grid is nondeterministic polynomial‐time hard, and often, metaheuristics techniques are applied to solve it. Genetic algorithm, a metaheuristic technique based on evolutionary computation, has been used to solve such complex optimization problem. This work proposes a technique for the grid scheduling problem using genetic algorithm with the objective to maximize availability. Simulation experiment, to evaluate the performance of the proposed algorithm, is conducted, and results reveal the effectiveness of the model. A comparative study has also been performed. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of fertilisation on the allyl isothiocyanate profile of above‐ground tissues of New Zealand‐grown wasabi

Wasabi (Wasabia japonica (Miq) Matsum) is a developing crop in New Zealand and is valued for its spicy taste and pungent smell. It is popular as a condiment for traditional and modern Japanese foods. However, the limited area suitable for wasabi production in Japan has resulted in inability to meet increasing market demand. Isothiocyanates (ITCs) are sulphur compounds responsible for the unique flavour of wasabi, with allyl isothiocyanate (AITC) being the main compound responsible for the pungency. In this study, AITC tissue concentration and yield were measured in three above‐ground tissues of the wasabi plant to investigate the effects of different fertiliser, manure and lime treatments. The highest tissue concentration of AITC was found in the rhizomes, ranging from 1564 to 3366 mg kg^?1 (fresh weight basis), while the petioles and leaves contained 254–373 and 453–643 mg kg^?1 respectively. Fertilisation with ammonium sulphate produced the highest‐quality rhizomes (72% increase in AITC yield) and petioles (64% increase), but the best response in the leaves (51%) resulted from the manure treatment. Nitrogen fertiliser alone reduced the AITC yield by up to 15%. These results should help in formulating guidelines for production of high‐quality wasabi tops containing high levels of AITC. © 2002 Society of Chemical Industry     

Kinetic model for reduction of iron oxide in molten slags by iron-carbon melt

Rate of reduction of iron oxide in iron and steelmaking slags by mass contents of dissolved carbon (>3%) in molten iron depends upon activity of FeO, temperature, mixing of bulk slag and other experimental conditions. A general kinetic model is developed by considering mass transfer of FeO in slag, chemical reaction at gas-metal interface and chemical reaction at gas-slag interface, respectively, as the three rate controlling steps. A critical analysis of the experimental data reported in literature has been done. It is shown that in the case of slags containing mass contents of less than 5% FeO, the reduction of FeO is controlled by mass transfer of FeO in slag plus chemical reaction at gas-metal interface; when slags contain more than 40% FeO, the reduction of FeO is controlled by chemical reaction at gas-metal interface plus chemical reaction at gas-slag interface; at intermediate FeO mass contents (between ～ 5 and 40% FeO), the reduction of FeO is controlled by all three steps, namely, mass transfer of FeO in slag, chemical reaction at gas-metal interface and chemical reaction at gas-slag interface. The temperature dependence of rate constant for the gas-slag reaction is obtained as: In k₂ = –32345.4(&6128)/ T + 19.0(&3.42); σ_lnk2,1/T = &0.3. where k₂ is expressed in mol m^-2 s^-1 bar^-1. The mass transfer coefficient of iron oxide in bulk slag is found to vary in the range 1.5 × 10^-5 to 5.0 × 10^-5 m/s, depending upon the slag composition as well as experimental conditions.     

Morphological changes during reduction of magnetite compacts

Magnetite superconcentrate compacts were reduced to wustite and iron at various temperatures (1173-1423 K) and the morphological changes occurring at various stages of reduction were observed under the scanning electron microscope. It has been demonstrated that considerable pitting and fragmentation occur during solid state reduction of Fe₃O₄ to FeO by solid iron. During the reduction of FeO the iron nuclei formed have a tetrahedral shape. At low reduction temperatures (1173 K) the large number of iron nuclei formed on wustite sinter together forming a dense iron layer. At high temperatures sustained growth of nuclei in the vertical direction leads to a sinuous porosity. Genesis of porosity creation has also been explained in terms of formation of holes, slits, cracks and fragmentation in magnetite and wustite and growth and sintering of iron nuclei.