In situ study of carbon nanotube formation by C2H2 decomposition on an iron-based catalyst

The properties and formation of nanotubes have been extensively studied, but very few deal with the catalytic production mechanism of nanotubes. Two different techniques, thermogravimetric analysis and UV-Raman, have been applied to analyse the carbon deposition by catalysed decomposition of acetylene over an iron-based catalyst. The nature of the produced carbon materials depends on reaction temperature. Also, TEM allows identification of carbon nanotubes, encapsulated particles, and other nanostructures, while UV-Raman confirms its graphitic and graphite-like nature. (C) 2000 Elsevier Science Ltd. All rights reserved.

A study on reduction behaviors of the supported platinum-iron catalysts

The reduction behaviors of the supported platinum-iron catalysts and their comparison with supported iron catalysts were studied by TPR (temperature-programmed reduction)-in situ Fe-57 MBS (Mossbauer spectroscopy). The results indicated that the TPR processes of all Fe-containing catalysts were different from that of bulk alpha-Fe2O3. There were interactions between Pt, Fe and the gamma-Al2O3 or SiO2 support for the Pt-Fe/gamma-Al2O3 and Pt-Fe/SiO2 catalysts. All the iron-containing catalysts show that Fe3+ was highly dispersed on the support (gamma-Al2O3 and SiO2) before reduction. No Fe-0 was found in the reduction processes. The Fe3+ was reduced to Fe2+ in tetrahedral vacancy first for the reduction of the Pt-Fe/gamma-Al2O3 catalyst. No Fe2+ in octahedral vacancy was found in the reduction of the Pt-Fe/SiO2 catalyst. Adding Pt to Fe/support (gamma-Al2O3 or SiO2) could promote the reduction of the Fe species. (C) 1999 Elsevier Science B.V. All rights reserved.

Characterization of iron atoms in the framework of MFI-type zeolites by UV resonance Raman spectroscopy

Silicalite-I, ZSM-5, and Fe-ZSM-5 zeolites prepared from two different silicon sources are characterized by UV resonance Raman (UVRR) spectroscopy, X-ray diffraction (XRD), electron spin resonance (ESR), and UV/visible diffuse reflectance spectroscopy (UV/Vis DRS). A new technique for investigating zeolitic structure, UV resonance Raman spectroscopy selectively enhances the Raman bands associated with framework iron atoms incorporated into MFI-type zeolites, and it is very sensitive in identifying the iron atoms in the framework of zeolites, while other techniques such as XRD, ESR, and UV/Vis DRS have failed in uncovering trace amounts of iron atoms in the framework of zeolites. (C) 2000 Academic Press.

Determination of total iron binding capacity of serum by capillary electrophoresis

A capillary electrophoresis (CE) technique for determining total iron binding capacity (TIBC) of serum has been developed. The optimum serum pretreatment involves the following major steps: at first, saturate serum transferrin with Fe+3; then, dissociate them completely after removing excess unbound Fe. Finally, complex the released iron with phenanthroline, a chromophore, to make suitable for the CE analysis. Ammonium acetate (pH = 5.0) was used as CE background electrolyte solution. In this system, a good linear correlation coefficient was maintained over the range 0.5 similar to 10 mu M (r = 0.9979, n =12). Seven adult serum samples were studied and the TIBC parameters measured. In the present system, 10 similar to 30 mu L serum is sufficient for determination. The study shows that the CE technique described is a powerful method for rapid, efficient, sensitive and reliable analysis and hence particularly suitable for clinical application.

The structure of nano sized poorly-crystalline iron oxy-hydroxides

In this thesis the structures of three nano sized poorly-crystalline iron oxy-hydroxides, feroxyhyte, ferrihydrite and schwertmannite, are studied and analyzed with the aim of clarifying some dubious structural features. The widely used Rietveld re�nement and EXAFS analysis are employed in order to address the consistency of the structural models proposed for these materials, one of which, feroxyhyte, is suggested in this thesis. Furthermore, a new computer program exploiting the Reverse Monte Carlo algorithm and the Debye Scattering Equation is presented and used in order to analyze the elusive structures of these iron oxy-hydroxides.

Hepcidin as a therapeutic tool to limit iron overload and improve anemia in β-thalassemic mice.

Excessive iron absorption is one of the main features of β-thalassemia and can lead to severe morbidity and mortality. Serial analyses of β-thalassemic mice indicate that while hemoglobin levels decrease over time, the concentration of iron in the liver, spleen, and kidneys markedly increases. Iron overload is associated with low levels of hepcidin, a peptide that regulates iron metabolism by triggering degradation of ferroportin, an iron-transport protein localized on absorptive enterocytes as well as hepatocytes and macrophages. Patients with β-thalassemia also have low hepcidin levels. These observations led us to hypothesize that more iron is absorbed in β-thalassemia than is required for erythropoiesis and that increasing the concentration of hepcidin in the body of such patients might be therapeutic, limiting iron overload. Here we demonstrate that a moderate increase in expression of hepcidin in β-thalassemic mice limits iron overload, decreases formation of insoluble membrane-bound globins and reactive oxygen species, and improves anemia. Mice with increased hepcidin expression also demonstrated an increase in the lifespan of their red cells, reversal of ineffective erythropoiesis and splenomegaly, and an increase in total hemoglobin levels. These data led us to suggest that therapeutics that could increase hepcidin levels or act as hepcidin agonists might help treat the abnormal iron absorption in individuals with β-thalassemia and related disorders.

Development of Stimulus-Responsive Ligands for the Modulation of Copper and Iron Coordination

The ability to manipulate the coordination chemistry of metal ions has significant ramifications for the study and treatment of metal-related health concerns, including iron overload, UV skin damage, and microbial infection among many other conditions. To address this concern, chelating agents that change their metal binding characteristics in response to external stimuli have been synthesized and characterized by several spectroscopic and chromatographic analytical methods. The primary stimuli of interest for this work are light and hydrogen peroxide.

Herein we report the previously unrecognized photochemistry of aroylhydrazone metal chelator ((E)-N′-[1-(2-hydroxyphenyl)ethyliden]isonicotinoylhydrazide) (HAPI) and its relation to HAPI metal binding properties. Based on promising initial results, a series of HAPI analogues was prepared to probe the structure-function relationships of aroylhydrazone photochemistry. These efforts elucidate the tunable nature of several aroylhydrazone photoswitching properties.

Ongoing efforts in this laboratory seek to develop compounds called prochelators that exhibit a switch from low to high metal binding affinity upon activation by a stimulus of interest. In this context, we present new strategies to install multiple desired functions into a single structure. The prochelator 2-((E)-1-(2-isonicotinoylhydrazono)ethyl)phenyl (E)-3-(2,4-dihydroxyphenyl)acrylate (PC-HAPI) is masked with a photolabile trans-cinnamic acid protecting group that releases umbelliferone, a UV-absorbing, antioxidant coumarin along with a chelating agent upon UV irradiation. In addition to the antioxidant effects of the coumarin, the released chelator (HAPI) inhibits metal-catalyzed production of damaging reactive oxygen species. Finally a peroxide-sensitive prochelator quinolin-8-yl (Z)-3-(4-hydroxy-2-((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)phenyl)acrylate (BCQ) has been prepared using a novel synthetic route for functionalized cis-cinnamate esters. BCQ uses a novel masking strategy to trigger a 90-fold increase in fluorescence emission, along with the release of a desired chelator, in the presence of hydrogen peroxide.

Optimizing the operation of straight-grate iron-ore pellet induration systems using process models

Mathematical models of straight-grate pellet induration processes have been developed and carefully validated by a number of workers over the past two decades. However, the subsequent exploitation of these models in process optimization is less clear, but obviously requires a sound understanding of how the key factors control the operation. In this article, we show how a thermokinetic model of pellet induration, validated against operating data from one of the Iron Ore Company of Canada (IOCC) lines in Canada, can be exploited in process optimization from the perspective of fuel efficiency, production rate, and product quality. Most existing processes are restricted in the options available for process optimization. Here, we review the role of each of the drying (D), preheating (PH), firing (F), after-firing (AF), and cooling (C) phases of the induration process. We then use the induration process model to evaluate whether the first drying zone is best to use on the up- or down-draft gas-flow stream, and we optimize the on-gas temperature profile in the hood of the PH, F, and AF zones, to reduce the burner fuel by at least 10 pct over the long term. Finally, we consider how efficient and flexible the process could be if some of the structural constraints were removed (i.e., addressed at the design stage). The analysis suggests it should be possible to reduce the burner fuel lead by 35 pct, easily increase production by 5+ pct, and improve pellet quality.

Micromagnetic simulation of domain walls in iron films

The micromagnetic structure and energy of 180° domain walls spanning laminar crystals of iron having (100) or (110) surfaces and ranging in thickness from 145 to 580 nm have been investigated by numerical integration of the Landau-Lifshitz-Gilbert equation. Stable equilibrium structures with two flux symmetries were obtained for both crystal orientations at all thicknesses studied.

Computational fluid dynamics: advancements in technology for modeling iron and steelmaking processes

Computational fluid dynamics (CFD) software technology has formed the basis of many investigations into the behavior and optimization of primary iron and steelmaking processes for the last 25+ years. The objective of this contribution is to review the progress in CFD technologies over the last decade or so and how this can be brought to bear in advancing the process analysis capability of primary ferrous operations. In particular, progress on key challenges such as compute performance, fluid-structure transformation and interaction, and increasingly complex geometries are highlighted.