Improved sugar cane juice clarification by understanding calcium oxide-phosphate-sucrose systems

It is accepted that the efficiency of sugar cane clarification is closely linked with sugar juice composition (including suspended or insoluble impurities), the inorganic phosphate content, the liming condition and type, and the interactions between the juice components. These interactions are not well understood, particularly those between calcium, phosphate, and sucrose in sugar cane juice. Studies have been conducted on calcium oxide (CaO)/phosphate/sucrose systems in both synthetic and factory juices to provide further information on the defecation process (i.e., simple liming to effect impurity removal) and to identify an effective clarification process that would result in reduced scaling of sugar factory evaporators, pans, and centrifugals. Results have shown that a two-stage process involving the addition of lime saccharate to a set juice pH followed by the addition of sodium hydroxide to a final juice pH or a similar two-stage process where the order of addition of the alkalis is reversed prior to clarification reduces the impurity loading of the clarified juice compared to that of the clarified juice obtained by the conventional defecation process. The treatment process showed reductions in CaO (27% to 50%) and MgO (up to 20%) in clarified juices with no apparent loss in juice clarity or increase in residence time of the mud particles compared to those in the conventional process. There was also a reduction in the SiO2 content. However, the disadvantage of this process is the significant increase in the Na2O content.

Low temperature synthesis of carbon nanotubes on indium tin oxide electrodes for organic solar cells

The electrical performance of indium tin oxide (ITO) coated glass was improved by including a controlled layer of carbon nanotubes directly on top of the ITO film. Multi-wall carbon nanotubes (MWCNTs) were synthesized by chemical vapor deposition, using ultra-thin Fe layers as catalyst. The process parameters (temperature, gas flow and duration) were carefully refined to obtain the appropriate size and density of MWCNTs with a minimum decrease of the light harvesting in the cell. When used as anodes for organic solar cells based on poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM), the MWCNT-enhanced electrodes are found to improve the charge carrier extraction from the photoactive blend, thanks to the additional percolation paths provided by the CNTs. The work function of as-modified ITO surfaces was measured by the Kelvin probe method to be 4.95 eV, resulting in an improved matching to the highest occupied molecular orbital level of the P3HT. This is in turn expected to increase the hole transport and collection at the anode, contributing to the significant increase of current density and open circuit voltage observed in test cells created with such MWCNT-enhanced electrodes.

Nitric oxide synthase type-II is synthesized by human gingival tissue and cultured human gingival fibroblasts

Nitric oxide is known to be an important inflammatory mediator, and is implicated in the pathophysiology of a range of inflammatory disorders. The aim of this study was to determine the localization and distribution of endothelial NOS (NOS-II) in human gingival tissue, and to ascertain if human gingival fibroblasts express NOS-II when stimulated with interferon gamma (IFN-gamma) and bacterial lipopolysaccharide (LPS). The distribution of NOS-II in inflamed and non-inflamed specimens of human gingivae was studied using a monoclonal antibody against nitric oxide synthase II. Cultures of fibroblasts derived from healthy human gingivae were used for the cell culture experiments. The results from immunohistochemical staining of the tissues indicated an upregulation of NOS-II expression in inflamed compared to non-inflamed gingival tissue. Fibroblasts and inflammatory cells within the inflamed connective tissue were positively stained for NOS-II. In addition, basal keratinocytes also stained strongly for NOS-II, in both healthy and inflamed tissue sections. When cultured human gingival fibroblasts were stimulated by INF-gamma and Porphyromonas gingivalis LPS, NOS-II was more strongly expressed than when the cells were exposed to LPS or IFN-gamma alone. These data suggest that, as for other inflammatory diseases, NO plays a role in the pathophysiology of periodontitis.

Nitrous oxide emissions from subtropical horticultural soils : a time series analysis

Time series regression models were used to examine the influence of environmental factors (soil water content and soil temperature) on the emissions of nitrous oxide (N2O) from subtropical soils, by taking into account temporal lagged environmental factors, autoregressive processes, and seasonality for three horticultural crops in a subtropical region of Australia. Fluxes of N2O, soil water content, and soil temperature were determined simultaneously on a weekly basis over a 12-month period in South East Queensland. Annual N2O emissions for soils under mango, pineapple, and custard apple were 1590, 1156, and 2038 g N2O-N/ha, respectively, with most emissions attributed to nitrification. The N2O-N emitted from the pineapple and custard apple crops was equivalent to 0.26 and 2.22%, respectively, of the applied mineral N. The change in soil water content was the key variable for describing N2O emissions at the weekly time-scale, with soil temperature at a lag of 1 month having a significant influence on average N2O emissions (averaged) at the monthly time-scale across the three crops. After accounting for soil temperature and soil water content, both the weekly and monthly time series regression models exhibited significant autocorrelation at lags of 1–2 weeks and 1–2 months, and significant seasonality for weekly N2O emissions for mango crop and for monthly N2O emissions for mango and custard apple crops in this location over this time-frame. Time series regression models can explain a higher percentage of the temporal variation of N2O emission compared with simple regression models using soil temperature and soil water content as drivers. Taking into account seasonal variability and temporal persistence in N2O emissions associated with soil water content and soil temperature may lead to a reduction in the uncertainty surrounding estimates of N2O emissions based on limited sampling effort.

Conductometric gas sensors based on nanostructured WO3 thin films

Nanostructured WO3 thin films have been prepared by thermal evaporation to detect hydrogen at low temperatures. The influence of heat treatment on the physical, chemical and electronic properties of these films has been investigated. The films were annealed at 400oC for 2 hours in air. AFM and TEM analysis revealed that the as-deposited WO3 film is high amorphous and made up of cluster of particles. Annealing at 400oC for 2 hours in air resulted in very fine grain size of the order of 5 nm and porous structure. GIXRD and Raman analysis revealed that annealing improved the crystallinity of WO3 film. Gas sensors based on annealed WO3 films have shown a high response towards various concentrations (10-10000 ppm) H2 at an operating temperature of 150oC. The improved sensing performance at low operating temperature is due to the optimum physical, chemical and electronic properties achieved in the WO3 film through annealing.

Synthesis and characterisation of nanoscale magnesium oxide powders and their application in thick films of Bi2Sr2CaCu2O8

Nanoscale MgO powder was synthesized from magnesite ore by a wet chemical method. Acid dissolution was used to obtain a solution from which magnesium containing complexes were precipitated by either oxalic acid or ammonium hydroxide, The transformation of precipitates to the oxide was monitored by thermal analysis and XRD and the transformed powders were studied by electron microscopy. The MgO powders were added as dopants to Bi2SrCa2CuO8 powders and high temperature superconductor thick films were deposited on silver. Addition of suitable MgO powder resulted in increase of critical current density, J(c), from 8,900 Acm(-2) to 13,900 Acm(-2) measured at 77 K and 0 T. The effect of MgO addition was evaluated by XRD, electron microscopy and critical current density measurements. (C) 1998 Elsevier Science B.V.

Bismuth oxide nanoparticles in the stratosphere

Platey grains of cubic Bi2O3, α-Bi2O3, and Bi2O2.75 nanograins were associated with chondritic porous interplanetary dust particles W7029C1, W7029E5, and 2011C2 that were collected in the stratosphere at 17-19 km altitude. Similar Bi oxide nanograins were present in the upper stratosphere during May 1985. These grains are linked to the plumes of several major volcanic eruptions during the early 1980s that injected material into the stratosphere. The mass of sulfur from these eruptions is a proxy for the mass of stratospheric Bi from which we derive the particle number densities (p m -3) for "average Bi2O3 nanograins" due to this volcanic activity and those necessary to contaminate the extraterrestrial chondritic porous interplanetary dust particles via collisional sticking. The match between both values supports the idea that Bi2O3 nanograins of volcanic origin could contaminate interplanetary dust particles in the Earth's stratosphere. Copyright 1997 by the American Geophysical Union.

Reaction products between Bi-Sr-Ca-Cu-oxide thick films and alumina substrates

The structure and composition of reaction products between Bi-Sr-Ca-Cu-oxide (BSCCO) thick films and alumina substrates have been characterized using a combination of electron diffraction, scanning electron microscopy and energy dispersive X-ray spectrometry (EDX). Sr and Ca are found to be the most reactive cations with alumina. Sr4Al6O12SO4 is formed between the alumina substrates and BSCCO thick films prepared from paste with composition close to Bi-2212 (and Bi-2212 + 10 wt.% Ag). For paste with composition close to Bi(Pb)-2223 + 20 wt.% Ag, a new phase with f.c.c. structure, lattice parameter about a = 24.5 A and approximate composition Al3Sr2CaBi2CuOx has been identified in the interface region. Understanding and control of these reactions is essential for growth of high quality BSCCO thick films on alumina. (C) 1997 Elsevier Science S.A.

Microstructural investigation of Bi-Sr-Ca-Cu-oxide thick films on alumina substrates

The microstructure of Bi-Sr-Ca-Cu-oxide (BSCCO) thick films on alumina substrates has been characterized using a combination of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy of sections across the film/substrate interface and energy-dispersive X-ray spectrometry. A reaction layer formed between the BSCCO films and the alumina substrates. This chemical interaction is largely responsible for off-stoichiometry of the films and is more significant after partial melting of the films. A new phase with fee structure, lattice parameter a = 2.45 nm and approximate composition Al3Sr2CaBi2CuOx has been identified as reaction product between BSCCO and Al2O3.

Titanium-oxide magneli phases in four chondritic porous interplanetary dust particles

Detailed analytical electron microscope analyses of four fine-grained chondritic porous interplanetary dust particles (IDPs)reveal the presence of titanium oxide Magneli phases, TinO2n-1 (n=4,5,6), and rare Ti-metal. The titanium minerals are indigenous to these chondritic IDPs. The association of Magneli phases, Ti-metal, and carbonaceous material in chondritic IDPs, along with the grain size distributions support in situ solid carbon gasification in these extraterrestrial particles. The active catalyst in this process is titanium metal that we infer may be of interstellar origin. This favorable catalysis uniquely leads to the formation of Magneli phases. As chondritic IDPs may be solid debris of short-period comets, our data indicate that nuclei of short-period comets may show distinctive chemical reactions that lead to Ti-mineral assemblages that typically include Magneli phases. The proposed model provides a plausible mechnism to explain the higher solid carbon content of chondritic IDPs relative to bulk carbon abundances typical for carbonaceous chondrite matrices that represent another type of more evolved, that is, metamorphosed, undifferentiated solar system bodies.

Oxide reduction in NiO-containing solid solution systems during transmission electron microscopy

The effects of electron irradiation on NiO-containing solid solution systems are described. Partially hydrated NiO solid solutions, e. g. , NiO-MgO, undergo surface reduction to Ni metal after examination by TEM. This surface layer results in the formation of Moire interference patterns.

Nitrous oxide emissions from irrigated wheat in Australia : impact of irrigation management

Background and Aims: Irrigation management affects soil water dynamics as well as the soil microbial carbon and nitrogen turnover and potentially the biosphere-atmosphere exchange of greenhouse gasses (GHG). We present a study on the effect of three irrigation treatments on the emissions of nitrous oxide (N2O) from irrigated wheat on black vertisols in South-Eastern Queensland, Australia. Methods: Soil N2O fluxes from wheat were monitored over one season with a fully automated system that measured emissions on a sub-daily basis. Measurements were taken from 3 subplots for each treatment within a randomized split-plot design. Results: Highest N2O emissions occurred after rainfall or irrigation and the amount of irrigation water applied was found to influence the magnitude of these “emission pulses”. Daily N2O emissions varied from -0.74 to 20.46 g N2O-N ha-1 day-1 resulting in seasonal losses ranging from 0.43 to 0.75 kg N2O N ha-1 season -1 for the different irrigation treatments. Emission factors (EF = proportion of N fertilizer emitted as N2O) over the wheat cropping season, uncorrected for background emissions, ranged from 0.2 to 0.4% of total N applied for the different treatments. Highest seasonal N2O emissions were observed in the treatment with the highest irrigation intensity; however, the N2O intensity (N2O emission per crop yield) was highest in the treatment with the lowest irrigation intensity. Conclusions: Our data suggest that timing and amount of irrigation can effectively be used to reduce N2O losses from irrigated agricultural systems; however, in order to develop sustainable mitigation strategies the N2O intensity of a cropping system is an important concept that needs to be taken into account.

Increased charge transfer of Poly (ethylene oxide) based electrolyte by addition of small molecule and its application in dye-sensitized solar cells

A Poly (ethylene oxide) based polymer electrolyte impregnated with 2-Mercapto benzimidazole was comprehensively characterized by XRD, UV–visible spectroscopy, FTIR as well as electrochemical impedance spectroscopy. It was found that the crystallization of PEO was dramatically reduced and the ionic conductivity of the electrolyte was increased 4.5 fold by addition of 2-Mercapto benzimidazole. UV–visible and FTIR spectroscopes indicated the formation of charge transfer complex between 2-Mercapto benzimidazole and iodine of the electrolyte. Dye-sensitized solar cells with the polymer electrolytes were assembled. It was found that both the photocurrent density and photovoltage were enhanced with respect to the DSC without 2-Mercapto benzimidazole, leading to a 60% increase of the performance of the cell.