Study of a titaniferous magnetite chlorination at high temperature

The chlorination of a titaniferous magnetite with low content in Ti and Fe has been studied between 1273 and 2273 K. Most of the hercynite and ilmenite initially present are decomposed during the gas-solid phase reaction between 1273 and 1823 K. Considerable ilmenite decomposition and FeCl₃evolution already occur at 1273 K, leaving a residue consisting of TiO₂, Fe₂O₃-TiO₂ (pseudobrookite), and about 50 pct of each of the Cr and Mg initially present. X-ray diffractograms shown the formation of Al₂TiO₅ which contributes to the stabilization of TiO₂ up to 1773 K, above which temperature significant decomposition of Al₂TiO₅ is observed. At the melting point of the titaniferous magnetite sample (around 1823 K), the presence of both solid and liquid phases result in a considerable decrease in the chlorination rate. In this respect, heating the sample under helium up to the melting point, so that liquid and solid phases are obtained at equilibrium, yields two structures replacing the magnetite present just prior to melting. One of these structures is of the spinel Fe₂TiO₄ type, while the other is a combination of the spinel types MgAl₂O₄, FeAl₂O₄, and MgCr₂O₄. When the sample is chlorinated, a high proportion of the initial Cr (90 pct) and Ti (80 pct) are found in the chlorination residue at the early stages of fusion, together with 13 pct of the initial Fe. Chlorination of the liquid phase between 1823 and 2273 K shows a steady decrease of Ti and Cr in the chlorination residue, associated with an increase of Fe content.     

Thermodynamic study of the behaviour of minor coal elements and their affinities to sulphur during coal combustion

The behaviours of ten minor coal elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Si and Ti) during coal combustion in the temperature range 400–2000 K, under both oxidising and reducing conditions, have been studied in detail by a thermodynamic equilibrium analysis.

The partitioning of these elements is calculated both in single minor element–coal–chlorine systems and in minor elements co-existing systems. Their vaporisation tendency is found in the order: (Si, Al)<(Fe, Ti)<(Ca, Mn)<(K, Na, P, Mg). Si, Ti, Al and P are present mostly as oxides and K and Na as chlorides, whatever the combustion conditions. Al, Ca, Fe, K, Mn and Na sulphates are dominant at low temperatures under oxidising conditions, whereas under reducing conditions most of them are sulphides and/or chlorides. Moreover, the interactions between these elements affect their major speciation: some species containing two elements among those studied are dominant in the minor elements co-existing systems. The affinities of minor coal elements to sulphur have been studied versus both temperature (400 or 800 K) and sulphur content (0.0062–6.20 wt.% in the coal), in order to find out their influence on the flue gas desulfurization. Two coal samples with different ash contents were considered, and it was found that the ash composition affects greatly the minor elements partitioning.     

Nanocomposite piezoelectric films of P(VDF‐TrFE)/LiNbO3

Piezoelectric films were prepared by incorporation of lithium niobate (LiNbO₃) nanoparticles into copolymer of vinylidene difluoride and trifluoroethylene. Nanoparticles of LiNbO₃ with ferroelectric phase were successfully synthesized and dispersed homogenously by ultrasonication in the copolymer matrix without any surfactant or surface functionalization. The nanocomposites were fully characterized by electronic microscopy, X‐ray diffraction, differential scanning calorimetry, dynamical mechanical analysis, and piezometer. Surprisingly, the copolymer matrix crystallinity and morphology were not affected by the incorporation of nanoparticles. Therefore the nanocomposites remained good mechanicals properties and high ferroelectricity coupled to nonlinear optical activity thanks to the noncentro symmetric space group of lithium niobate. This could be a novel approach to develop new multifunctional materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of transparent PMMA/Fe(IO3)3 nanocomposite films from microemulsion polymerization

Polymethyl methacrylate (PMMA)/Fe(IO₃)₃ nanocomposite thin films are obtained by in situ particle generation in microemulsions and subsequent photopolymerization of a mixture containing methyl methacrylate, trimethylolpropane triacrylate, and crystallized iron iodate (Fe(IO₃)₃) nanorods. Hyper‐Rayleigh scattering measurements combined with X‐ray diffraction, transmission electron microscopy, and dynamic light scattering are first used to probe in situ the crystallization kinetics of iron iodate nanorods in water‐in‐oil microemulsions prepared with methyl methacrylate as the oil phase and marlophen NP12 as a surfactant. Trimethylolpropane triacrylate is then added as a crosslinker before spin‐coating. Films are deposited on glass substrates for the nonlinear optical characterizations and on silicon wafers for the piezoelectric and mechanical measurements. Nanocomposite films treated by corona discharge are finally characterized through optical microscopy, laser Doppler vibrometry, and Brillouin spectroscopy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1203‐1211, 2013     

Hypersensitivity of ataxia telangiectasia fibroblasts to ionizing radiation is associated with a repair deficiency of DNA double-strand breaks

Amphiregulin (Ar) is an EGF receptor ligand that functions to modulate the growth of both normal and malignant epithelial cells. We asked whether mouse preimplantation embryos express Ar, and if so, what the function of Ar is during preimplantation development. We used RT-PCR to show expression of Ar mRNA in mouse blastocysts, and using a polyclonal anti-Ar antibody and indirect immunofluorescence, we detected the presence of Ar protein in morula- and blastocyst-stage embryos. Ar protein was present in both the cytoplasm and nucleus in both morulae- and blastocyst-stage embryos, which is similar to Ar distribution in other cell types. Embryos cultured in Ar developed into blastocysts more quickly and also exhibited increased cell numbers compared to control embryos. In addition, 4-cell stage embryos cultured in an antisense Ar phosphorothioate-modified oligodeoxynucleotide (S-oligo) for 48 hr exhibited slower rates of blastocyst formation and reduced embryo cell numbers compared to embryos exposed to a random control S-oligo. TGF-alpha significantly improved blastocyst formation, but not cell numbers, for embryos cultured in the antisense Ar S-oligo. From these observations, we propose that Ar may function as an autocrine growth factor for mouse preimplantation embryos by promoting blastocyst formation and embryo cell number. We also propose that blastocyst formation is stimulated by Ar and TGF-alpha, while Ar appears to exert a greater stimulatory effect on cell proliferation than does TGF-alpha in these embryos.     

The cost-effective fault detection and fault location approach for communication channels in NoC

In the current paper, we propose a new online search, fault detection, and fault location approach for short faults in network on chip communication channels. The approach proposed consists of a built-in self-test as well as a packet/flit comparings module embedded in the network adapter and a router, respectively. The approach is mainly characterized by the fact that, firstly, the diagnosis and location processes are simultaneously carried out after which the test time is minimized. Secondly, the approach updates the NoC routing tables far less costly in a parallel fashion. Thirdly, insignificant hardware is added to the system. The high scalability in the approach, in addition, leads to 100% test coverage, 71.4% capability of detecting faulty channels, and 100% detected faults location in one round (two phases). The simulation results show that the approach hardware is optimized compared with the previous methodologies.     

Capacity of activated carbon derived from pistachio shells by H3PO4 in the removal of dyes and phenolics

Two activated carbons were obtained from pistachio shells by impregnation with H₃PO₄ under standard conditions of acid concentration (50 wt%) and heat treatment at 773 K for 2 h. The soaking time was 24 and 72 h for the two samples before thermal pyrolysis. Analysis of the N₂/77 K adsorption isotherms proved that both were highly adsorbing carbons with considerable microporosity, and that the prolonged contact with activant enhanced total porosity (surface area and pore volume) and increased the amount of mesoporosity. Adsorption isotherms of probe molecules, viz methylene blue (MB), rhodamine B (RB), phenol (P) and p‐nitrophenol (PNP), were determined at room temperature, from aqueous solutions. Both the Langmuir and Freundlich model adsorption equations show satisfactory fit to experimental data. Both carbons exhibit similar adsorption parameters irrespective of their porosity characteristics. The sequence of uptake per unit weight was: PNP > MB > RB > P. Low affinity towards phenol may be associated with its competition with water molecules which are more favourably attracted to the acid surface which has a high oxygen functionality. Preferred adsorption in the order PNP > MB > RB is proposed to be a function of carbon porosity, related to the increased molecular dimensions of the solutes. Adsorption from a binary mixture of equal concentrations of MB and RB showed reduced uptake for both sorbates in comparison to the single component experiments. RB removal surpasses that of MB in the binary test and may be attributed to lower water solubility and higher molecular dimensions. Copyright © 2003 Society of Chemical Industry     

Decomposition of H2O2 on activated carbon obtained from olive stones

Activated carbons were prepared from olive oil solid wastes by treatment in different schemes: impregnation with H₃PO₄ followed by pyrolysis at 300–700 °C, by steam pyrolysis at 600–700 °C, or by conventional steam activation at 850 °C. Porosity characteristics were determined by analysis of nitrogen adsorption isotherms, and carbons of widely different properties and surface pH values were obtained. Decomposition of H₂O₂ in dilute unbuffered solution was followed by measuring evolved oxygen volumetrically. First‐order kinetics was followed, and the catalytic rate coefficients were evaluated. The carbons tested showed appreciable activity where evolved oxygen attained ≈10% of the stoichiometric amount in 1 h. The degree of decomposition showed inverse dependence on surface area, pore volume and mean pore dimensions. The chemical nature of the surface, rather than the porosity characteristics, was the principal factor in enhancing the disproportionation of H₂O₂ on the activated carbon surface. © 2001 Society of Chemical Industry     

Automatic zone identification in scientific papers via fusion techniques

Scientometrics - Zone identification is a topic in the area of text mining which helps researchers be benefited by the content of scientific papers in a satisfactory manner. The major aim of zone...     

Synthesis,sintering, and effect of surface roughness on oxidation of submicron Ti2AlC ceramics

Submicron Ti₂AlC MAX phase powder was synthesized by molten salt shielded synthesis (MS³) using a Ti:Al:C molar ratio of 2:1:0.9 at a process temperature of 1000°C for 5  hours. The synthesized powder presented a mean particle size of ~0.9 µm and a purity of 91 wt. % Ti₂AlC, containing 6 wt. % Ti₃AlC₂. The Ti₂AlC powder was sintered by pressureless sintering, achieving a maximal relative density of 90%, hence field-assisted sintering technology/spark plasma sintering was used to enhance densification. The fine-grained microstructure was preserved, and phase purity of Ti₂AlC was unaltered in the latter case, with a relative density of 98.5%. Oxidation was performed at 1200°C for 50 hours in static air of dense monolithic Ti₂AlC with different surface finish, (polished, ground and sandblasted) which resulted in the formation of an approx. 8 µm thin aluminum oxide (Al₂O₃) layer decorated with titanium dioxide (rutile, TiO₂) colonies. Surface quality had no influence on Al₂O₃ scale thickness, but the amount and size of TiO₂ crystals increased with surface roughness. A phenomenon of rumpling of the thermally grown oxide (TGO) was observed and a model to estimate the extent of deformation is proposed.