Study on ash deposition under oxyfuel combustion of coal/biomass blends

Combustion in an O₂/CO₂ mixture (oxyfuel) has been recognized as a promising technology for CO₂ capture as it produces a high CO₂ concentration flue gas. Furthermore, biofuels in general contribute to CO₂ reduction in comparison with fossil fuels as they are considered CO₂ neutral. Ash formation and deposition (surface fouling) behavior of coal/biomass blends under O₂/CO₂ combustion conditions is still not extensively studied. Aim of this work is the comparative study of ash formation and deposition of selected coal/biomass blends under oxyfuel and air conditions in a lab scale pulverized coal combustor (drop tube). The fuels used were Russian and South African coals and their blends with Shea meal (cocoa). A horizontal deposition probe, equipped with thermocouples and heat transfer sensors for on line data acquisition, was placed at a fixed distance from the burner in order to simulate the ash deposition on heat transfer surfaces (e.g. water or steam tubes). Furthermore, a cascade impactor (staged filter) was used to obtain size distributed ash samples including the submicron range at the reactor exit. The deposition ratio and propensity measured for the various experimental conditions were higher in all oxyfuel cases. The SEM/EDS and ICP analyses of the deposit and cascade impactor ash samples indicate K interactions with the alumina silicates and to a smaller extend with Cl, which was all released in the gas phase, in both the oxyfuel and air combustion samples. Sulfur was depleted in both the air or oxyfuel ash deposits. S and K enrichment was detected in the fine ash stages, slightly increased under air combustion conditions. Chemical equilibrium calculations were carried out to facilitate the interpretation of the measured data; the results indicate that temperature dependence and fuels/blends ash composition are the major factors affecting gaseous compounds and ash composition rather than the combustion environment, which seems to affect the fine ash (submicron) ash composition, and the ash deposition mechanisms.     

A novel pyruvate kinase (PK-S) from boar spermatozoa is localized at the fibrous sheath and the acrosome

Boar spermatozoa contain a novel pyruvate kinase (PK-S) that is tightly bound at the acrosome of the sperm head and at the fibrous sheath in the principal piece of the flagellum, while the midpiece contains a soluble pyruvate kinase (PK). PK-S could not be solubilized by detergents, but by trypsin with no loss of activity. Purified PK-S as well as PK-S still bound to cell structures and soluble sperm PK have all kinetics similar to those of rabbit muscle PK-M1. The PK-S subunit had a relative molecular mass of 64 +/- 1 x 10(3) (n = 3), i.e. slightly higher than that of PK-M1, and carried an N-terminal extension (NH(2)-TSEAM-COOH) that is lacking in native PK-M1. Evidence is provided that PK-S is encoded by the PKM gene. Antibodies produced against the N-terminus of purified PK-S (NH(2)-TSEAMPKAHMDAG-COOH) were specific for PK-S as they did not react with somatic PKs or soluble sperm PK, while anti-PK-M1 recognized both sperm PKs. Immunofluorescence microscopy showed anti-PK-S to label the acrosome and the flagellar principal piece, whereas the midpiece containing the mitochondria was labelled only by anti-PK-M1. Immunogold labelling confirmed the localization of PK-S at the acrosome. In the principal piece, both polyclonal anti-PK-M1 and anti-PK-S were found at the fibrous sheath. Our results suggest that PK-S is a major component in the structural organization of glycolysis in boar spermatozoa.     

Assessment of MRF for simultaneous T1 and T2 quantification and water–fat separation in the liver at 0.55 T

Magnetic Resonance Materials in Physics, Biology and Medicine - The goal of this work was to assess the feasibility of performing MRF in the liver on a 0.55 T scanner and to examine the...     

Optimization of paste formulation for TiO2 nanoparticles with wide range of size distribution for its application in dye sensitized solar cells

Dye sensitized solar cell (DSSC) can be an economically viable and technically simpler alternate to the silicon based solar cells. Films of nanocrystalline titanium dioxide (TiO₂) are considered as the most suitable photoelectrode for DSSC. For this study, TiO₂ powder of anatase phase, synthesized in acidic environment was used. The average diameter of the nanoparticles was ～20 nm and BET surface area was 64.68 m²/g. Different TiO₂ pastes were prepared by varying the proportion of TiO₂ powder, α-terpineol, and ethyl cellulose (EC) in their composition. The TiO₂ paste was cast on fluorine doped tin oxide (FTO) coated glass surface using doctor blade to prepare photoelectrode of TiO₂ film. Composition of the paste ingredients was optimized by comparing the conversion efficiencies of the DSSCs fabricated with the photoelectrode of thickness ～18 μm. The outcome of this study can be crucial for the preparation of reliable TiO₂ paste in a simple way for its application in DSSC.     

Physics-based lithium ion silver vanadium oxide cathode model

A cathode half cell physics-based model for a St. Jude Medical fabricated silver vanadium oxide (SVO) cathode coin cell battery was constructed. The model is based on a single particle Fick's second law approach with the open-circuit potential modeled with a Redlich-Kister equation. By assuming that lithium ions intercalate only through the ends of the cuboid SVO particles, the model is able to predict accurately the discharge profile of experimental cathode half cell coin cells.     

Molecular Determinants of Carbocation Cyclisation in Bacterial Monoterpene Synthases

Monoterpene synthases are often promiscuous enzymes, yielding product mixtures rather than pure compounds due to the nature of the branched reaction mechanism involving reactive carbocations. Two previously identified bacterial monoterpene synthases, a linalool synthase (bLinS) and a cineole synthase (bCinS), produce nearly pure linalool and cineole from geranyl diphosphate, respectively. We used a combined experimental and computational approach to identify critical residues involved in bacterial monoterpenoid synthesis. Phe77 is essential for bCinS activity, guiding the linear carbocation intermediate towards the formation of the cyclic α-terpinyl intermediate; removal of the aromatic ring results in variants that produce acyclic products only. Computational chemistry confirmed the importance of Phe77 in carbocation stabilisation. Phe74, Phe78 and Phe179 are involved in maintaining the active site shape in bCinS without a specific role for the aromatic ring. Phe295 in bLinS, and the equivalent Ala301 in bCinS, are essential for linalool and cineole formation, respectively. Where Phe295 places steric constraints on the carbocation intermediates, Ala301 is essential for bCinS initial cyclisation and activity. Our multidisciplinary approach gives unique insights into how carefully placed amino acid residues in the active site can direct carbocations down specific paths, by placing steric constraints or offering stabilisation via cation-π interactions.     

Defect characterization in boron implanted silicon after flash annealing

Flash-assisted rapid thermal processing (fRTP) has gained considerable interests for fabrication of ultra-shallow junction in silicon. fRTP can significantly reduce boron diffusion, while attaining boron activation at levels beyond the limits of traditional rapid thermal annealing. The efficiency of fRTP for defect annealing, however, needs to be systematically explored. In this study, a (1 0 0) silicon wafer was implanted with 500 eV boron ions to a fluence of 1 × 10¹⁵ cm⁻². fRTP was performed with peak temperatures ranging from 1100 °C to 1300 °C for approximately one milli-second. High resolution transmission electron microscopy and secondary ion mass spectrometry were performed to characterize as-implanted and annealed samples. The study shows that fRTP at 1250 °C can effectively anneal defects without causing boron tail diffusion.     

Real-time rectilinear volumetric imaging

Current real-time volumetric scanners use a 2-D array to scan a pyramidal volume consisting of many sector scans stacked in the elevation direction. This scan format is primarily useful for cardiac imaging to avoid interference from the ribs. However, a real-time rectilinear volumetric scan with a wider field of view close to the transducer could prove more useful for abdominal, breast, or vascular imaging. In previous work, computer simulations of very sparse array transducer designs in a rectilinear volumetric scanner demonstrated that a Mills cross array showed the best overall performance given current system constraints. Consequently, a 94×94 Mills cross array including 372 active channels operating at 5 MHz has been developed on a flexible circuit interconnect. In addition, the beam former delay software and scan converter display software of the Duke volumetric scanner were modified to achieve real-time rectilinear volumetric scanning consisting of a 30-mm×8-mm×60-mm scan at a rate of 47 volumes/s. Real-time rectilinear volumetric images were obtained of tissue-mimicking phantoms, showing a spatial resolution of 1 to 2 mm. Images of carotid arteries in normal subjects demonstrated tissue penetration to 6 cm     

From sustainability to adaptation: Goldman Sachs’ corporate real estate strategy

This paper is premised on a conceptual framework that attempts to draw theoretical and practical connections between sustainability, resilience and adaptation. The framework is explored through a case study of the corporate real estate (property) strategies of Goldman Sachs (a multinational investment banking and investment management company) developed over the course of the consolidation and development of its corporate headquarters. This case seeks to identify the existence and nature of the relationships by and between sustainable corporate real estate strategies, resilient operations planning and the firm's adaptive capacity. A secondary proposition seeks to evaluate whether the capacity of the firm to adapt and be resilient to changing conditions has been positively advanced by the firm's sustainable corporate real estate strategies. The findings support the proposition that these connections do exist, as well as the proposition that sustainability was promoting adaptive capacity and operational resilience. However, it remains an open question to what extent these practices and capacities are deterministic of one another. This paper sets the stage for future research that seeks to measure and model organizational adaptive capacity and to understand the potential co-benefits that may serve the interests of firms who struggle to rationalize the costs of sustainability.