Continued Heating Research Articles

Scanned-wavelength-modulation-spectroscopy sensor for CO, CO2, CH4 and H2O in a high-pressure engineering-scale transport-reactor coal gasifier

In-situ laser-absorption measurements of CO, CO2, CH4 and H2O were demonstrated in the synthesis gas products of coal gasification (here called syngas) from an engineering-scale transport reactor. A wavelength-scanned, wavelength-modulation spectroscopy scheme was used to counter environmental challenges including severe loss in transmitted light intensity due to particulate scattering and beam steering in the synthesis gas stream. Separate lasers were used for each species (CO near 2326nm, CO2 near 2017nm, CH4 near 2290nm, and H2O near 1352nm) and a novel fiber bundle was utilized to combine all four beams on a common optical path. Line-of-sight laser absorption utilized sapphire windows in the synthesis gas product pipe downstream of the gasifier reactor by approximately 5s flow time. Time multiplexing enabled low-noise measurement of the transmitted light with a single detector. Successful measurements of the four species mole fractions were performed throughout the 54day measurement campaign, including a significant period of unattended operation. The mole fractions of the four target species were monitored versus time as the gasifier was transitioned from a cold startup to stabilization at the target 15atm and 1260K gasification condition, and after 35days at relatively steady operating conditions, the campaign was terminated and the reactor shut down. The variations of time-resolved mole fractions of the four species were captured during the heating of the reactor with a propane/air flame, the continued combustion heating of the reactor as coal was added to the fuel, and the transition from combustion to gasification. The average values of CO, CO2 and CH4 measured by the laser absorption sensor were in good agreement with extractive gas chromatography; however, the extractive gas analysis was delayed by ∼20min and had a ∼15min time response due to the transport and conditioning (filtering and drying) of the sampled gas. The laser absorption sensor provided essentially simultaneous species mole fractions with sub-second time resolution, which enabled identification of a wide range of dynamic behaviors. For example, small changes in the reactor conditions due to batch feeding of coal were observed by composition changes in the synthesis gas and were correlated with small temperature fluctuations in the reactor.

Petrology and geochemistry of the Valle de Santiago lower-crust xenoliths: Young tectonothermal processes beneath the central Trans-Mexican volcanic belt

We present a comprehensive petrologic study of lower-crust mafic and felsic xenoliths hosted by Quaternary alkaline basalts of the Valle de Santiago monogenetic volcanic field. This is the only locality along the entire Trans-Mexican volcanic belt where the abundance and size of xenoliths allow the understanding in great detail of processes associated with interactions of young subduction-related magmatism and the deep continental crust. Mafic xenoliths (two pyroxene ± spinel granulites and metanorthosites), olivine-rich gabbroic xenoliths, and transitional xenoliths compose the bulk of the population, although a few belong to the charnockitic suite (enderbite and faersundite). Thermobarometric calculations (two-pyroxene, ilmenite-magnetite, Ti-in amphibole, amphibole-plagioclase, and phase equilibria in the system NCMAS (Na-Ca-Mg-Si)) result in pressures around 9 kbar and temperatures of 1000–1100 °C for the granulite-facies metamorphism, which would give a very hot lower crust, ∼33 km thick, beneath Valle de Santiago and a mean geothermal gradient of ∼30 °C/km. Igneous zircons (Th/U = 0.03–0.87) extracted from one of the felsic granulites yielded a major peak of latest Cretaceous age (67.1 Ma), interpreted as the crystallization age of the granitic protolith, without inheritance from Precambrian or Paleozoic crust. Minor peaks at 45.1 and 25.5 Ma are interpreted as partial Pb losses from some of the Cretaceous zircons. Trace-element geochemistry, as well as Sr, Nd, and Pb isotopic studies performed on two granulites, is consistent with the juvenile and coeval nature of both the mafic metagabbroic xenoliths and the alkaline basaltic magmas that lifted the xenoliths from the lower crust. Two intermediate stages in the thermal evolution of the sampled xenoliths include the emplacement at different depths of volatile and K-Fe-Ti–rich oxidized melts represented by igneous assemblages with kaersutite, biotite, titanomagnetite, spinel, plagioclase, Fe-rich epidote, clinopyroxene, fayalitic olivine, and glasses that pervasively invaded most granulite xenoliths before being taken to the surface. A preferred plumbing system model is presented depicting a protracted Miocene to Quaternary basaltic intraplate magmatic system that sampled former basaltic batches stationed in the lower crust, together with the Late Cretaceous deep-seated granitoids beneath Valle de Santiago in the backarc of the central Trans-Mexican volcanic belt. Both components were later subjected to granulite-facies conditions in the lower crust, most probably related to the continued heating of the crust by basaltic magmas underplated in the central Trans-Mexican volcanic belt backarc region.

On the filling and leakage of petroleum from traps in the Laminaria High region of the northern Bonaparte Basin, Australia

A 3D petroleum systems model of the northern Bonaparte Basin indicates that the potential Nancar Trough source kitchen could be currently expelling hydrocarbons from numerous Jurassic source rocks into traps on the Laminaria High. Based on a range of kinetic models defined for such source rocks within the Plover, Laminaria and Frigate formations, two phases of hydrocarbon generation are predicted. Source rocks within the Lower Cretaceous Echuca Shoals Formation are immature for hydrocarbon generation in this region. Hydrocarbon generation in the Laminaria High commenced during the mid to late Cenozoic, and in the Nancar Trough during the Early Cretaceous, in response to elevated heat flow during the syn-rift phase. The second and main phase of hydrocarbon generation and expulsion started in the mid-Eocene and is ongoing. This phase was controlled by deposition of the thick Cenozoic carbonate shelf, which resulted in deep burial and continued heating of the Mesozoic source rocks. This second phase of expulsion coincided with the reactivation of fault-bounded traps, the consequence of which is that either some or all of the initially trapped hydrocarbons have escaped out of the charged structures. Thus, the most plausible explanation for the occurrence of under-filled and dry structures within the study area is that the faults bounding these traps remained permeable from the late Miocene to the present-day. Secondary alteration processes including water washing and phase fractionation are necessary to explain the bulk composition of Laminaria High and neighbouring under-saturated light oil accumulations.

Effect of Au Nanoparticle Spatial Distribution on the Stability of Thin Polymer Films

The stability of thin poly(methyl-methacrylate) (PMMA) films of low molecular weight on a solid substrate is controlled by the areal coverage of gold nanoparticles (NPs) present at the air-polymer interface. As the polymer becomes liquid the Au NPs are free to diffuse, coalesce, and aggregate while the polymer film can change its morphology through viscous flow. These processes lead at the same time to the formation of a fractal network of Au NPs and to the development of spinodal instabilities of the free surface of the polymer films. For thinner films a single wavelength is observed, while for thicker films two wavelengths compete. With continued heating the aggregation process results in a decrease in coverage, the networks evolve into disordered particle assemblies, while the polymer films flatten again. The disordering occurs first on the smallest scales and coincides (in thicker films) with the disappearance of the smaller wavelength. The subsequent disordering on larger scales causes the films to flatten.

Structural Characterization and Redox Catalytic Properties of Cerium(IV) Pyrochlore Oxides

Ce(IV) pyrochlore oxides have been prepared by hydrothermal synthesis, and the parent material, a sodium cerium titanate, has been studied using total neutron scattering. While analysis of Bragg diffraction is consistent with an average cubic pyroclore structure, the profile is broadened because of the crystal size of <10 nm. Analysis of the pair distribution function (PDF) produced by Fourier transformation of the total scattering yields a structural model consistent with formulation of the parent material as (Na0.33Ce0.53Ti0.14)2Ti2O7. This contains a proportion of A-site titanium, consistent with the measured bulk density of the material. The PDF also contains evidence that the short-range order of the pyrochlore structure is disordered, with oxide anions displaced from the positions of the ideal Fd3m pyrochlore structure to give local symmetry F43m. These observations are supported by static (broadline) solid state 49Ti NMR measurements on a 49Ti isotopically enriched sample, which showed a dominant, narrow resonance at an apparent shift of δ – 912 ppm and a second minor resonance consistent with A-site titanium. Sn(IV) doping of the pyrochlore phase is possible by one-step hydrothermal synthesis: this gives a series of materials with a maximum tin content of Sn:Ti = 0.4:0.6, for which 119Sn solid-state NMR confirms the presence of octahedral, B-site Sn(IV), and powder X-ray diffraction shows an associated expansion of the pyrochlore lattice. Temperature programmed reduction/oxidation studies of the materials reveal that after an activation cycle the parent pyrochlore shows a reversible low temperature reduction at <200 °C, more facile than ceria itself. The Sn-doped analogues also show a low temperature reduction, but on continued heating collapse irreversibly to yield a mixture of products that includes SnO. The parent pyrochlore has been tested as a support for gold in the water gas shift reaction and shows a lower temperature conversion of H2O and CO to H2 and CO2 than a ceria sample of similar surface area.

Isothermal, mass-limited rarefactions in planar and spherical geometry

Solutions are developed for isothermal, mass-limited rarefactions in which the temperature is held constant by continued heating. The case of spatially constant temperature and fixed total energy is also revisited. These solutions are useful in the context of experiments in which plasmas are continuously heated for long periods (up to tens of ns) by present-day lasers or hohlraums.

Observation of trapped gas during electrical resistance heating of trichloroethylene under passive venting conditions

A two-dimensional experiment employing a heterogeneous sand pack incorporating two pools of trichloroethylene (TCE) was performed to assess the efficacy of electrical resistance heating (ERH) under passive venting conditions. Temperature monitoring displayed the existence of a TCE-water co-boiling plateau at 73.4 °C, followed by continued heating to 100 °C. A 5 cm thick gas accumulation formed beneath a fine-grained capillary barrier during and after co-boiling. The capillary barrier did not desaturate during the course of the experiment; the only pathway for gas escape being through perforated wells traversing the barrier. The thickness of the accumulation was dictated by the entry pressure of the perforated well. The theoretical maximum TCE soil concentration within the region of gas accumulation, following gas collapse, was estimated to be 888 mg/kg. Post-heating soil sampling revealed TCE concentrations in this region ranging from 27 mg/kg to 96.7 mg/kg, indicating removal of aqueous and gas phase TCE following co-boiling as a result of subsequent boiling of water. The equilibrium concentrations of TCE in water corresponding to the range of post-treatment concentrations in soil (6.11 mg/kg to 136 mg/kg) are calculated to range from 19.8 mg/l to 440 mg/l. The results of this experiment illustrate the importance of providing gas phase venting during the application of ERH in heterogeneous porous media.

Relaxation of the shear modulus of a metallic glass near the glass transition

Precise in situ measurements of the high-frequency (f≈560 kHz) shear modulus G of Pd40Cu30Ni10P20 bulk metallic glass at heating rates 0.38≤T·≤7.5 K/min have been performed. It has been found that structural relaxation leads to an increase of G below the glass transition temperature Tg while decreasing it at T&amp;gt;Tg. A quantitative analysis of this phenomenon within the framework of the interstitialcy theory has shown that structural relaxation below Tg can be understood as a decrease of the concentration of interstitialcy-like defects frozen-in upon glass production. The relaxation turns into defect multiplication on continued heating above Tg. The beginning of defect multiplication represents the glass transition temperature. An excellent agreement between calculated and experimental Tg ’s as a function of the heating rate has been found.

The Genesis of Distal Zinc Skarns: Evidence from the Mochito Deposit, Honduras

The Mochito deposit, located in Honduras, is a distal Zn(-Pb-Ag) skarn in which economic mineralization (sphalerite and subordinate, argentiferous galena) is found in mantos and chimneys dominated by garnet and pyroxene that replaced limestone and a mixed limestone-siliciclastic unit. Except for a few variably altered, unmineralized diabase dikes, evidence of igneous activity is conspicuously absent. The nearest felsic igneous rocks, volcanic rock units, crop out ~13 km from the deposit. Early skarn and skarn proximal to faults consist dominantly of garnet that evolved from grandite, with a composition of ~Ad55 to andradite (≥Ad90), whereas later skarn, or skarn distal to faults, is mainly made up of pyroxene (Hd70). Magnetite and pyrrhotite locally form between the garnet and pyroxene skarns. Analyses of the whole-rock chemistry show that formation of grandite skarn involved large additions of all major elements (except Ca) and most trace elements, whereas formation of andradite skarn (from grandite skarn) involved losses of most of these elements; the notable exceptions are Ca and Fe, which were added. Mass changes in pyroxene skarn were not evaluated because of the heterogeneous nature of the precursor. Primary fluid inclusions in grandite and associated low-iron sphalerite are interpreted to have been trapped at ~370°C and a pressure of 500 bar. These inclusions have a mean salinity of 14 wt percent NaCl equiv. By contrast, primary inclusions in pyroxene and associated high-iron sphalerite were trapped at ~400°C and have a mean salinity of 5 wt percent NaCl equiv. Fluid inclusions could not be observed in andradite. Small proportions of CO2, CH4, and N2 were detected by gas chromatographic analyses of the fluids released by crushing small samples of the host mineral; CO2 was the most abundant of these gases. Based on LA-ICPMS analyses of individual fluid inclusions, Na and Ca were the principal metals in the fluids (median concentrations of 3.2 wt %), followed by K (0.9 wt %) and Mn (0.3 wt %). Median concentrations of ore metals Zn, Pb, and Ag were 6,000, 900, and 50 ppm, respectively. Analyses of phase equilibria and related thermodynamic calculations indicate that the log f O2 during the grandite and pyroxene skarn stages was >–30.3 and <–30.2, respectively. The pH during the grandite stage was ~5.0. In the absence of reliable data on bulk fluid chemistry, a pH for the pyroxene stage could not be estimated. Based on the calculated Si content of the fluid and the mass addition of Si during grandite skarn formation, the fluid/rock ratio was between 500:1 and 1,000:1. Evaluation of the solubility of sphalerite, galena, and argentite based on the physicochemical characteristics of the putative ore fluid indicate that the ore metals were transported dominantly as chloride complexes and deposited in response to an increase in pH. We propose a model in which relatively oxidizing hydrothermal fluids, exsolving from magma at a depth of >4 km, interacted with graphitic limestones in the Mochito graben during an episode of mid-Tertiary intraplate extension. These fluids rose through faults created by the extension and were cooled by the overlying sedimentary succession. Early skarn formed in an environment of high-fluid flux proximal to the faults and was dominated by grandite because of the oxidizing nature of the fluids. With continued heating of the rocks by subsequent pulses of fluid, temperature increased and the locus of interaction expanded into unaltered limestone distal to the faults, where lower fluid/rock ratios and the presence of graphite promoted buffering of the fluid to lower f O2 and formation of pyroxene skarn. Ore mineral deposition (dominantly sphalerite), which began during or after the formation of grandite skarn, reached its maximum after hydrothermal activity was focused in the lower fluid/rock ratio regime of pyroxene skarn formation, occurring in response to the sharp drop in pH that accompanied neutralization of the fluid by limestone.

High-Accuracy X-Ray Diffraction Analysis of Phase Evolution Sequence During Devitrification of Cu50Zr50 Metallic Glass

Real-time high-energy X-ray diffraction (HEXRD) was used to investigate the crystallization kinetics and phase selection sequence for constant-heating-rate devitrification of fully amorphous Cu50Zr50, using heating rates from 10 K/min to 60 K/min (10 °C/min to 60 °C/min). In situ HEXRD patterns were obtained by the constant-rate heating of melt-spun ribbons under synchrotron radiation. High-accuracy phase identification and quantitative assessment of phase fraction evolution though the duration of the observed transformations were performed using a Rietveld refinement method. Results for 10 K/min (10 °C/min) heating show the apparent simultaneous formation of three phases, orthorhombic Cu10Zr7, tetragonal CuZr2 (C11b), and cubic CuZr (B2), at 706 K (433 °C), followed immediately by the dissolution of the CuZr (B2) phase upon continued heating to 789 K (516 °C). Continued heating results in reprecipitation of the CuZr (B2) phase at 1002 K (729 °C), with the material transforming completely to CuZr (B2) by 1045 K (772 °C). The Cu5Zr8 phase, previously reported to be a devitrification product in C50Zr50, was not observed in the present study.

Precursor-mediated dissociation of n-butane on a PdO(1 0 1) thin film

We investigated the molecular adsorption and dissociation of n-butane on a PdO(1 0 1) thin film using temperature-programmed reaction spectroscopy (TPRS) experiments and density functional theory (DFT) calculations. At low coverage, n-butane adsorbs on PdO(1 0 1) in a molecular state that is more strongly bound than n-butane physisorbed on Pd(1 1 1). This molecularly adsorbed state of n-butane on PdO(1 0 1) corresponds to a σ-complex that forms on the rows of coordinatively unsaturated (cus) Pd atoms of the oxide surface. TPRS results show that a fraction of the n-butane layer undergoes C–H bond cleavage below ∼215 K and that the resulting fragments are completely oxidized by the surface upon continued heating. The evolution of product yields with the n-butane coverage as well as site blocking experiments provide strong evidence that the n-butane σ-complex serves as the precursor to initial C–H bond cleavage of n-butane on PdO(1 0 1). DFT calculations confirm the formation of an n-butane σ-complex on PdO(1 0 1). In the preferred bonding geometry, the n-butane molecule aligns parallel to a cus-Pd row and adopts a so-called η 1(2H) configuration with two coordinate H–Pd bonds per molecule. Our DFT calculations also show that σ-complex formation weakens C–H bonds, causing bond elongation and vibrational mode softening. For methane, we predict that coordination with a cus-Pd atom lowers the barrier for C–H bond cleavage on PdO(1 0 1) by more than 100 kJ/mol. These results demonstrate that dative bonding between alkane molecules and cus-Pd atoms serves to electronically activate C–H bonds on PdO(1 0 1) and suggest that adsorbed σ-complexes play a general role as precursors in alkane activation on transition metal oxide surfaces.

Nanoparticles of nickel oxide and nickel hydroxide using lyophilisomes of fibrinogen as template

Stable lyophilisomes of fibrinogen at pH 7.5 have been prepared by the method of a rapid freezing–heating and annealing sequence. Reduction of the lyophilisomes of the nickel–fibrinogen complex coated on solid substrates and subsequent heating showed formation of nickel hydroxide and finally nickel oxide. Ultraviolet–visible spectroscopy has been used to monitor the thin films of pure fibrinogen microcapsules, as well as the subsequent nucleation and growth of nanoparticles within the supramolecular structure. Transmission electron microscopy showed initially a thread-like structure which disappeared on continued heating, resulting in nanoparticles ranging from 10 to 50nm. Particle-size distribution of product was analyzed by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED), and Brunauer–Emmett–Teller (BET) N2 adsorption. The results suggest that the NiO particles have a body-centered cubic structure and are well dispersed. The particle-size distribution ranges from 10 to 50nm with an average particle size about 28nm, and the specific surface area is 34m2/g. Magnetic study carried out on the prepared nanoparticles showed a ferromagnetic behavior.

Formation of carbon capsules from an amorphous carbon film by Ga and Ni/Co catalysts in a transmission electron microscope

Direct conversion of an amorphous carbon (C) film to capsules by gallium (Ga), and nickel and cobalt (NiCo) alloy particles upon heating is investigated in situ by transmission electron microscopy (TEM). Capsules are catalyzed in an NH3 atmosphere when the temperature is raised to 1050 °C. High resolution TEM reveals that graphene flakes initially nucleate at the surface of the catalysts, then segregate and transform into faceted multi-shell capsules upon continued heating. The solubility of carbon in the NiCo alloy particles can be differentiated from the solubility of carbon in Ga particles by the thickness of the walls. The C/Ga binary phase in nanoparticles is discussed regarding the formation of thin-walled carbon capsules.

Factors Affecting Bubble Size on Foamed Polymer-Paperboard Composites

Foamed paperboard is a composite material with applications in the consumer products industry. The composite comprises a layer of paperboard sandwiched between two polymer films. One film foams upon heating while the other acts as a barrier. Foaming is caused by the vaporization of the small amount of moisture present in the board. The resulting increase in pressure bubbles the heat-softened polymer. During growth, the vapor driving force, which depends on the rate of vaporization, overcomes the opposing sheet resistance. Upon continued heating, the vapor escapes through the molten polymer film and from the sides of the board. Less than 2% of the total initial moisture accumulates inside the foam. The average bubble size is about five times lower than the maximum possible bubble size because of moisture losses. The final bubble size and foam thickness are dictated by the degree of bubble coalescence.

LC and LC-MS Study on Establishment of Degradation Pathway of Glipizide Under Forced Decomposition Conditions

Forced degradation studies on glipizide are conducted under the conditions of hydrolysis, oxidation, photolysis, and dry heat. The solutions are subjected to liquid chromatographic (LC) investigations to establish the number of products formed in each condition. The degradation products are characterized through isolation and subsequent NMR, IR, and MS spectral analyses, or through LC-mass spectrometry (MS) fragmentation pattern study. The drug is shown to degrade in 0.1M HCl at 85 degrees C to two products: 5-methyl-N-[2-(4-sulphamoylphenyl)ethyl]pyrazine-2-carboxamide (II) and methyl N-[4-[2-{(5-methyl-2-pyrazinoyl)amino}ethyl] phenyl]sulfonyl carbamate (III). The latter, a methyl ester, is formed only in the presence of methanol (used as a solubilizer), and does not appear on use of acetonitrile. III is shown to convert to II on continued heating in acid. The drug degrades slowly in water at the same temperature, and both II and III could be seen in the chromatograms until the end of the study. The heating of the drug in alkali (0.1M NaOH) at 85 degrees C yields 5-methyl-2-pyrazinecarboxylic acid (IV), along with a small quantity of 4-(2-aminoethyl) benzenesulfonamide (I). On extended heating in the same condition, a new product, 4-(2-aminoethyl)-N,N-bis[(cyclohexylamino)carbonyl] benzenesulfonamide (VI) is formed in small quantities. At the lower temperature of 40 degrees C, the drug converts under each hydrolytic condition and in both the absence and presence of light to products II, III, or IV, along with a new product, 1-cyclohexyl-3-[[4-(2aminoethyl)phenyl] sulfonyl]urea (V). The light catalyzes formation of V, and it is formed until one or two weeks, after which its level decreases. The drug remains stable in 30% H2O2, except that products II and III appear as small peaks due to acidic character of the peroxide solution. Also, the drug remains unaffected in solid state under thermal and photolytic stress conditions. Based on the results, a more complete picture on degradation pathway of the drug is obtained, highlighting a clear advantage of the approach suggested by International Conference on Harmonization.

Dynamic simulation on effect of flame arrangement on thermal process of regenerative reheating furnace

By analyzing the characteristics of combustion and billet heating process, a 3-D transient computer fluid dynamic simulation system based on commercial software CFX4.3 and some self-programmed codes were developed to simulate the thermal process in a continuous heating furnace using high temperature air combustion technology. The effects of different switching modes on injection entrancement of multi burners, combustion and billet heating process in furnace were analyzed numerically, and the computational results were compared with on-site measurement, which verified the practicability of this numerical simulation system. The results indicate that the flow pattern and distribution of temperature in regenerative reheating furnace with partial same-side-switching combustion mode are favorable to satisfy the high quality requirements of reheating, in which the terminal heating temperature of billets is more than 1 460 K and the temperature difference between two nodes is not more than 10 K. But since the surface average temperature of billets apart from heating zone is only about 1 350 K and continued heating is needed in soaking zone, the design and operation of current state are still needed to be optimized to improve the temperature schedule of billet heating. The distribution of velocity and temperature in regenerative reheating furnace with same-side-switching combustion mode cannot satisfy the even and fast heating process. The terminal heating temperature of billets is lower than that of the former case by 30 K. The distribution of flow and temperature can be improved by using cross-switching combustion mode, whose terminal temperature of billets is about 1 470 K with small temperature difference within 10 K.

From Radio to X‐Ray: The Quiescent Atmosphere of the dMe Flare Star EV Lacertae

We report on multi-wavelength observations spanning radio to X-ray wavelengths of the M dwarf flare star, EV Lacertae, probing the characteristics of the outer atmospheric plasma from the upper chromosphere to the corona. We detect the star at a wavelength of 2 cm (15 GHz) for the first time. UV and FUV line profiles show evidence of nonthermal broadening, and the velocity width appear to peak at lower temperatures than in the Sun; this trend is confirmed in another active M dwarf flare star. Electron density measurements indicate nearly constant electron pressures between $\log T=$5.2 and 6.4. At higher coronal temperatures, there is a sharp increase of two orders of magnitude in density (n$_{e}\sim10^{13}$ cm$^{-3}$ at $\log T=$6.9). X-ray, EUV, FUV and NUV spectra constrain the DEM from the upper chromosphere through the corona. The coronal pressures are inconsistent with the assumption of hydrostatic equilibrium, either through EM modeling or application of scaling laws, and imply large conductive loss rates and a large energy input at the highest temperatures. The timescales for radiative and conductive losses in EV Lac's upper atmosphere imply that significant continued heating must occur for the corona to maintain its quiescent properties. The high frequency radio detection requires the high temperature X-ray-emitting coronal plasma to be spatially distinct from the radio emission source. Length scales in the low-temperature corona are markedly larger than those in the high-temperature corona, further suggestions of an inhomogeneous mixture of thermal and nonthermal coronal plasma.

Thermal and Mineral Properties of Al-, Cr-, Mn-, Ni- and Ti-Substituted Goethite

AbstractMineralogical and thermal characteristics of synthetic Al-, Cr-, Mn-, Ni- and Ti-bearing goethites, synthesized via alkaline hydrolysis of metal-ferrihydrite gels, were investigated by powder X-ray diffraction and differential thermal analysis. Shifts in unit-cell dimensions were consistent with size of substituent metal ions and confirmed the incorporation of Al3+, Cr3+, Mn3+, Ni2+ and Ti4+ in the goethite structure. A weight loss of 6.2 wt.% for goethite containing 12.2 mol.% Ti, being significantly less than for stoichiometric goethite, is consistent with the replacement of Fe by Ti in the goethite structure coupled with the substitution of O2− ions for OH− (i.e. proton loss). These data provide the first confirmation of the direct replacement of Fe by Ti within goethite. Formation of multiple dehydroxylation endotherms for goethite containing 4.5 mol.% Al, 15.3 mol.% Mn and 12.2 mol.% Ti was not attributed to the decomposition of surface OH groups or related simply to the crystallinity of precursor goethite (‘high-a’ vs. ‘low-a’) as defined by the magnitude of a. Instead, endotherm doublet formation was associated with weight loss due to the dehydroxylation of goethite remaining after initial phase transformation to protohematite and to the evolution of OH− associated with the rapid increase in crystallite size of protohematite directed primarily along the a direction. Development of the first endotherm is due to initial dehydroxylation and transformation to protohematite. With continued heating of well ordered goethite or goethite containing moderate to high levels of substituent cations, domain growth along the a direction is delayed or inhibited to a critical point that provides enough thermal energy to enable goethite transformation to proceed to completion and for proto-hematite domain growth to occur. This results in the formation of a second endotherm. For less well ordered goethite and/or goethite containing only low levels of foreign metal cations, protohematite domain growth is not inhibited and proceeds continuously with heating to give only a single endotherm.

Effect of thermal processing on genistein, daidzein and glycitein content in soymilk

AbstractSoymilk was subjected to various heat treatments at 95, 121 and 140 °C for various lengths of time. The contents of the aglycones of isoflavone (daidzein, glycitein and genistein) of the soymilk were determined using C18 reversed‐phase high‐performance liquid chromatography. Genistein showed greater stability to heat treatment than daidzein and glycitein. Both the daidzein and glycitein contents decreased rapidly during the early stage of heating, but on continued heating the rates of decrease were much slower. Heating may cause an increase or decrease in the genistein content of soymilk depending on the temperature and time used. Upon heating at 95 and 121 °C, there was an increase in the genistein content in the early stage of heating, possibly due the conversion of genistin to genistein. Heating at 140 °C for more than 15 s and prolonged heating at 95 and 121 °C, however, caused a slow decline in the genistein content. Copyright © 2006 Society of Chemical Industry

Pyrolysis and gasification of pellets from sugar cane bagasse and wood

Wood pellets have become a popular form of biomass for power generation and residential heating due to easier handling both for transportation and for feeders in the treatment units, improved conversion and storage possibilities. The research on wood pellets as fuel has also been intensified during the past decade. However, other biomass sorts in pellet form, such as sugar cane bagasse, have not yet been extensively studied, especially not physical effects on the pellets during thermal treatment. Bagasse and wood pellets of different origin and sizes, shredded bagasse and wood chips have been studied in a thermogravimetric equipment to compare the effects of sort, origin, size and form of biomass during slow pyrolysis and steam gasification. Physical parameters such as decrease of volume and mass during treatment, as well as pyrolysis and gasification rates are of primary interest in the study. An important observation from the study is that for pellets the char density decreased during pyrolysis to a minimum around 450 °C, but thereafter increased with continued heating. The wood chips behaved differently with a continuous char density decrease during pyrolysis. Another conclusion from the work is that the size of the pellet has larger impact on the shrinkage behaviour throughout the conversion than the raw material, which the pellet is made of.