Mixed waste ferrite as a novel sorbent for carbon dioxide derived from flue gases

Ferrite is a potential sorbent for flue gases such as CO₂, H₂S and SO₂. This paper discusses the adsorption and decomposition of CO₂ into carbon by hydrogen-activated waste ferrites prepared from Berkeley Pit acid mine water (Butte, MT). The decomposition effectiveness of these waste ferrites was studied at 300 °C and compared with the synthetic magnetite obtained from ferrous sulfate solution in our laboratory. The decomposition was measured by two methods: indirectly by measuring the adsorption rate of CO₂ and directly by analysing the carbon deposited on the samples. The results indicated that the mixed waste ferrite had good affinity for the adsorption and decomposition. The CO₂ decomposition data of both sorbents fitted the first-order reaction kinetics. Even though the surface area of the magnetite was higher than that of waste ferrite, the CO₂ decomposition rate of the waste ferrite was estimated to be 2.5 times higher than that of magnetite under identical conditions. The carbon analysis deposited on the sample indicated that the CO₂ was 100% decomposed into carbon and other carbon/hydrogen compounds by the waste ferrite, whereas the conversion was 43% by the magnetite. In terms of specific adsorption of carbon, ferrite was three to five times more efficient than magnetite.     

Exploiting information theory for adaptive mobility and resource management in future cellular networks

We utilize tools from information theory to develop adaptive algorithms for two key problems in cellular networks: location tracking and resource management. The use of information theory is motivated by the fundamental observation that overheads in many aspects of mobile computing can be traced to the randomness or uncertainty in an individual user's movement behavior. We present a model-independent information-theoretic approach for estimating and managing this uncertainty, and relate it to the entropy or information content of the user's movement process. Information-theoretic mobility management algorithms are very simple, yet reduce overhead by /spl sim/80 percent in simulated scenarios by optimally adapting to each individual's movement. These algorithms also allow for flexible tradeoff between location update and paging costs. Simulation results demonstrate how an information-theory-motivated resource provisioning strategy can meet QoS bounds with very small wastage of resources, thus dramatically reducing the overall blocking rate.     

Studies of photoconductivity in β-Apo-8′ carotenal

The photoconductive properties of a carotenoid polyene,β-Apo-8′ carotenal in polycrystalline form has been studied. The growth of the photocurrent shows an overshoot in the growth-time curve before steady state value is attained. This behaviour of photocurrent is proposed to be due to higher value of recombination coefficient than trapping coefficient. From the temperature dependence study it is observed that the steady state photocurrent, at first increases with increase of temperature, attains a maximum at a particular temperatureT _max and then decreases with temperature. TheT _max value agrees with the temperature above and below which steady state photocurrent is attained differently. Monomolecular and bimolecular recombination processes at two temperature regimes are proposed to account for the observed behaviour. The dependence of photocurrent with excitation light intensity and wavelength study provide information on the carrier generation processes. The fast decay of photocurrent have been observed at different temperatures and from this study the decay constant is calculated and it is found to be temperature independent.     

Evaluation of the reactivity of titanium with mould materials during casting

A methodology for evaluating the reactivity of titanium with mould materials during casting has been developed. Microhardness profiles and analysis of oxygen contamination have provided an index for evaluation of the reactivity of titanium. Microhardness profile delineates two distinct regions, one of which is characterised by a low value of hardness which is invariant with distance. The reaction products are uniformly distributed in the metal in this region. The second is characterised by a sharp decrease in microhardness with distance from the metal-mould interface. It represents a diffusion zone for solutes that dissolve into titanium from the mould. The qualitative profiles for contaminants determined by scanning electron probe microanalyser and secondary ion mass spectroscopy in the as-cast titanium were found to be similar to that of microhardness, implying that microhardness can be considered as an index of the contamination resulting from metal-mould reaction.     

Chloroquine, quinine and quinidine inhibit calcium release from macrophage intracellular stores by blocking inositol 1,4,5-trisphosphate binding to its receptor

Endocrine and exocrine pancreatic morphogenesis is known to occur from ductal epithelium, but the factors that regulate this process are unknown. Vascular endothelial growth factor (VEGF)/vascular permeability factor has recently been reported to affect fetal islet ontogenesis. VEGF is an angiogenic factor with a growth-promoting effect that is thought to be restricted to vascular endothelial cells. We demonstrated that VEGF is also a mitogen for adult rat pancreatic duct epithelial cells in primary culture. VEGF supplementation to a serum-free culture medium increased the 5-bromo-2'-deoxyuridine-pulse labeling index of ductal cells more than 2-fold. Immunohistochemical staining and protein blots revealed that pancreatic duct cells express fetal liver kinase-1 high-affinity receptors for VEGF. In pancreatic tissue, immunohistochemistry shows that VEGF peptide is expressed in normal pancreatic islet cells. In duct ligation-induced acute pancreatitis, numerous inflammatory leukocytes containing VEGF were seen to infiltrate between hyperplastic ducts. In the latter model, islet neogenesis has previously been observed. Our data indicate the possibility that VEGF plays a role in the paracrine regulation of ductal growth and differentiation in vivo, eg, in pancreatitis. In vitro, however, VEGF did not induce endocrine differentiation of ductal cells, indicating that it is not the only factor required for the activation of islet neogenesis.     

The repassivation of nickel-copper alloys in sulphuric acid

The behaviour of freshly generated electrode surfaces of Ni, Ni-30Cu, Ni-50Cu and Ni-70Cu in 1.0 M H₂SO₄ has been investigated. At low potentials all metals grow a monolayer of film designated as MOH when M is Cu⁺ or Ni⁺. The kinetics of formation of this monolayer follows Tafel's equation. At higher potentials passivation of the metals occurs by film growth under high electric field, with two different sets of high field parameters for different film thicknesses. The rate of film growth for all metals is controlled largely by the nickel oxide component of the film.     

Crystallization of poly(3‐hydroxybutyrate) by exfoliated graphite nanoplatelets

Poly(3‐hydroxybutyrate) (PHB) has been shown to be efficiently nucleated by exfoliated graphite nanoplatelets (xGnP). The nucleating effect of xGnP was investigated using differential scanning calorimetry, optical microscopy and atomic force microscopy. Nonisothermal crystallization of PHB from the melt required lower activation energies for PHB containing 1 wt % and 3 wt % xGnP (?214 and ?102 kJ/mol respectively) than for pure PHB (?60 kJ/mol). A kinetic study of the PHB/xGnP crystallization employing a modified form of the Avrami equation revealed that the presence of xGnP increased the PHB crystallization temperature, as well as the crystallization rates, and generated smaller and more numerous spherulites. Optical microscopy and atomic force microscopy confirmed the incorporation of xGnP into the lamellar structure of the PHB spherulites and provided insight into the influence of xGnP on spherulite size and lamellae thickness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Polybutylene terephthalate/high-density polyethylene alloys. I. Morphological studies

Polybutylene terephthalate (PBT) is a commercially successful thermoplastic polyester but has certain drawbacks such as low impact strength and low melt strength. An attempt has been made to modify the properties of PBT by blending it with polyolefin such as highdensity polyethylene (HDPE). Since PBT and HDPE are incompatible, an ionomer has been used as a compatibilizer to form an alloy. Alloys of PBT and HDPE with varying amounts (2-8%) of ionomer were prepared by melt blending. The ultimate mechanical properties improved significantly on the addition of the ionomer due to an increase in interfacial adhesion between PBT and HDPE. DSC studies show that the presence of ionomer facilitated the crystallization of PBT in the alloy. DMTA studies show that more of PBT (amorphous) is going in to the HDPE-rich phase in the presence of ionomer. The morphology of the alloys was studied using scanning electron microscopy (SEM), polarizing microscopy (PM), and small-angle light scattering (SALS). They showed improved dispersion of HDPE domains in PBT matrix with increasing ionomer content and change in the type of superstructure on adding the ionomer. It has been shown that an alloy of PBT and HDPE with improved mechanical properties and homogeneous morphology can be made with use of ionomer as a compatibilizer. Such alloys are cost effective and can find use in several engineering applications.