Rice husk co-firing with coal in a short-combustion-chamber fluidized-bed combustor (SFBC)

This study encompassed the characteristics and performance of co-firing rice husk, a by-product of rice-milling process, with coal in a short-combustion-chamber fluidized-bed combustor (SFBC). Bed phenomena investigated in a cold-flow model combustor showed that with the different mixes of materials, the anticipated offshoot of combustion, the minimum fluidizing velocity (U_mf) was 0.4-0.8 m/s. In concord with axial temperature profiles, axial gas concentration profiles implied that a recirculating ring was able to circumscribe CO within the short-main chamber. The formation, decomposition, and eventual maturity of NO_x characterized the NO_x evolution, inferred from concentration profiles. The impacts of fluidizing velocity and blending ratio on gas emissions and combustion efficiency (E_c) are described. The fluidizing velocity had consequential effect on gas emissions, except NO_x. Surprisingly, NO_x did not hinge much on increased N-content of the mixtures with coal. As expected, increased SO₂ was relevant to increased coal mass. Increased fluidizing velocity adversely affected E_c while increased coal fraction enhanced E_c, mostly >97%.     

Self Assembly and Properties of C:WO3 Nano-Platelets and C:VO2/V2O5 Triangular Capsules Produced by Laser Solution Photolysis

Laser photolysis of WCl₆ in ethanol and a specific mixture of V₂O₅ and VCl₃ in ethanol lead to carbon modified vanadium and tungsten oxides with interesting properties. The presence of graphene’s aromatic rings (from the vibrational frequency of 1,600 cm⁻¹) together with C–C bonding of carbon (from the Raman shift of 1,124 cm⁻¹) present unique optical, vibrational, electronic and structural properties of the intended tungsten trioxide and vanadium dioxide materials. The morphology of these samples shows nano-platelets in WO _x samples and, in VO _x samples, encapsulated spherical quantum dots in conjunction with fullerenes of VO _x . Conductivity studies revealed that the VO₂/V₂O₅ nanostructures are more sensitive to Cl than to the presence of ethanol, whereas the C:WO₃ nano-platelets are more sensitive to ethanol than atomic C.     

Syntheses of pure (9Z, 11Z), (9E, 11E), (9E, 11Z), and (9Z,11E)-9,11-hexadecadienals-possible candidate pheromones

The title compounds were prepared by six different routes, and recommendations are given for the more convenient procedures in laboratory-scale syntheses. Modifications in the literature preparations of the 9E,11E and 9E,11Z isomers are described. Baseline separation of a prepared mixture of all four isomers of the (9Z, 11Z), (9E, 11E), (9E, 11Z), and (9Z, 11E)-9,11-hexadecadienals was achieved using GC methods with standard capillary columns. [¹³C]NMR spectroscopy of the alkene carbon atoms clearly differentiates between theZ,Z, E,E and eitherE,Z orZ,E isomers of the precursor dienols and thus of the dienals.     

Impedance spectroscopy data for S2O8 anion electroreduction at Bi(1 1 1) plane

Electroreduction kinetics of the peroxodisulfate anions on the electrochemically polished Bi(1 1 1) single crystal electrode has been studied by impedance spectroscopy. Influence of the electrode potential, reaction intermediates, base electrolyte and reactant concentrations on the kinetic parameters of electroreduction has been established. Systematic analysis of the fitting results demonstrates the noticeable influence of adsorption of the reaction intermediate or reactant on the electroreduction rate of the S₂O₈²⁻ anions at the Bi(1 1 1) electrode. In the region of so-called “current pits” in the cyclic voltammetry curves, obtained by rotating disc electrode method, the mixed kinetics, i.e. the adsorption and “true” charge transfer limited steps have been established by impedance spectroscopy.     

Synthesis and electrochemical properties of monoclinic Li3V2(PO4)3/C composite cathode material prepared from a sucrose-containing precursor

Monoclinic structure Li₃V₂(PO₄)₃/C composite powders are synthesized via a novel homogeneous mixing route followed by a one-step heat treatment. The composites were characterized by X-ray diffraction (XRD) and galvanostatic charge/discharge, CV measurements. The influence of the heat treatment on the electrochemical properties of Li₃V₂(PO₄)₃/C composites was investigated. To examine the effect of residual carbon content on the properties of the composites, six samples with 1.2, 2.3, 3.4, 4.4, 5.8, and 7.0 wt% carbon were prepared. The sample with 4.4 wt% carbon exhibited good cycling performance and rate capability in the range of 3.0–4.8 V.     

g-B3N3C: a novel two-dimensional graphite-like material

A novel crystalline structure of hybrid monolayer hexagonal boron nitride (BN) and graphene is predicted by means of the first-principles calculations. This material can be derived via boron or nitrogen atoms which are substituted by carbon atoms evenly in the graphitic BN with vacancies. The corresponding structure is constructed from a BN hexagonal ring linking an additional carbon atom. The unit cell is composed of seven atoms, three of which are boron atoms, three are nitrogen atoms, and one is a carbon atom. It shows a similar space structure as graphene, which is thus coined as g-B₃N₃C. Two stable topological types associated with the carbon bond formation, i.e., C-N or C-B bonds, are identified. Interestingly, distinct ground states of each type, depending on C-N or C-B bonds, and electronic bandgap as well as magnetic properties within this material have been studied systematically. Our work demonstrates a practical and efficient access to electronic properties of two-dimensional nanostructures, providing an approach to tackling open fundamental questions in bandgap-engineered devices and spintronics.     

Evaluation of embeddable potential sensor for corrosion monitoring in concrete structures

Embeddable potential sensor based on MnO₂ was assembled and characterised in concrete. The stability, reversibility, polarisability and impedance characteristics have been studied with respect to known reference. The corrosion performance of reinforced steel with respect to MnO₂ sensor was monitored by different electrochemical techniques. Reversibility of MnO₂ sensor indicated that difference of ±5 mV between the forward and reverse scan indicates the better reversibility characteristics in concrete. The rebar potentials (E_R) of steel with respect to MnO₂ are −315 and −525 mV for passive and active conditions of rebar in concrete. The corrosion current from potentiodynamic polarisation and R_ct from a.c. impedance technique clearly differentiated the behaviour of steel embedded in chloride contaminated concrete (active condition) from uncontaminated concrete (passive condition) with respect to MnO₂ sensor. All these studies revealed that corrosion monitoring of steel in concrete using embedded MnO₂ as a better potential sensor for steel in concrete. In addition it is easy to fabricate for amenable miniaturisation, varied configuration as demanded for corrosion monitoring in concrete structures.     

Synthesis and characterization of MoOx-Pt/C and TiOx-Pt/C nano-catalysts for oxygen reduction

The oxygen reduction reaction (ORR) was studied at carbon supported MoO_x-Pt/C and TiO_x-Pt nanocatalysts in 0.5 mol dm⁻³ HClO₄ solution, at 25 °C. The MoO_x-Pt/C and TiO_x-Pt/C catalysts were prepared by the polyole method combined by MoO_x or TiO_x post-deposition. Home made catalysts were characterized by TEM and EDX techniques. It was found that catalyst nanoparticles were homogenously distributed over the carbon support with a mean particle size about 2.5 nm. Quite similar distribution and particle size was previously obtained for Pt/C catalyst. Results confirmed that MoO_x and TiO_x post-deposition did not lead to a significant growth of the Pt nanoparticles.The ORR kinetics was investigated by cyclic voltammetry and linear sweep voltammetry at the rotating disc electrode. These results showed the existence of two E − log j regions, usually observed with polycrystalline Pt in acid solution. It was proposed that the main path in the ORR mechanism on MoO_x-Pt/C and TiO_x-Pt/C catalysts was the direct four-electron process with the transfer of the first electron as the rate-determining step. The increase in catalytic activity for ORR on MoO_x-Pt/C and TiO_x-Pt/C catalysts, in comparison with Pt/C catalyst, was explained by synergetic effects due to the formation of the interface between the platinum and oxide materials and by spillover due to the surface diffusion of oxygen reaction intermediates.     

Reactive infiltration processing (RIP) of ultra high temperature ceramics (UHTC) into porous C/C composite tubes

A novel reactive infiltration processing (RIP) technique was employed to infiltrate porous carbon fibre reinforced carbon (C/C) composite hollow tubes with ultra high temperature ceramic (UHTC) particles such as ZrB₂. The C/C composite tubes had initial porosity of ∼60% with a bimodal (10 μm and 100 μm) pore size distribution. A slurry with 40-50% ZrB₂ solid loading particles was used to infiltrate the C/C tubes. Our approach combines in situ ZrB₂ formation with coating of fine ZrB₂ particles on carbon fibre surfaces by a reactive processing method. A Zr and B containing diphasic gel was first prepared using inorganic-organic hybrid precursors of zirconium oxychloride (ZrOCl₂·8H₂O), boric acid, and phenolic resin as sources of zirconia, boron oxide, and carbon, respectively. Then commercially available ZrB₂ powder was added to this diphasic gel and milled for 6 h. The resultant hybrid slurry was vacuum infiltrated into the porous hollow C/C tubes. The infiltrated tubes were dried and fired for 3 h at 1400 °C in flowing Ar atmosphere to form and coat ZrB₂ on the carbon fibres in situ by carbothermal reaction. Microstructural observation of infiltrated porous C/C composites revealed carbon fibres coating with fine nanosized (∼100 nm) ZrB₂ particles infiltrated to a depth exceeding 2 mm. Ultra high temperature ablation testing for 60 s at 2190 °C suggested formation of ZrO₂ around the inner bore of the downstream surface.     

Sex pheromone biosynthesis of (E,E)-8,10-dodecadienol in codling mothCydia pomonella involvesE9 desaturation

Sex pheromone biosynthesis in the codling mothCydia pomonella (Lepidoptera; Tortricidae) was studied by topical application of deuterated fatty acids in DMSO to pheromone glands. The incorporation of deuterium label into fatty acids and alcohols in the pheromone gland was monitored by gas chromatography with flame ionization detection and mass spectrometry in the selected ion monitoring mode. Dodecanol, (E)-9-dodecenol, (E,E)-8,10-dodecadienol, tetradecanol, and hexadecanol were found in gland extracts. The application of [12,12,12-²H₃]dodecanoic acid resulted in labeled dodecanol, (E)-9-dodecenol, and (E,E)-8,10-dodecadienol, as well as the corresponding labeled acids. No label was incorporated into tetradecanol or hexadecanol or any acid with more than 12 carbon atoms. The application of labeled tetradecanoic or hexadecanoic acid introduced label not only into the 12-carbon alcohols, but also into tetradecanol, or tetradecanol and hexadecanol, respectively. The application of (E)-[11, 11,12,12,12,-²H₅]9-dodecen-oic acid, whose facile synthesis is described, resulted in labeled (E)-9-do-decenol and (E,E)-8,10-dodecadienol. The (E,E)-8,10-dodecadienol so produced was characterized by an ion atm/z 186, equivalent to [M]⁺ of a dienol labeled with four deuterons. Thus, one deuterium label is lost when the labeled (E)-9-monoene is converted to the (E,E)-8,10-diene. We conclude that (E,E)-8,10-dodecadienol is synthesized by chain shortening (-oxidation) of palmitic acid to dodecanoic acid, followed by an unusualE9 desaturation and subsequent conversion of this intermediate into the conjugated precursor, which is finally reduced to the pheromone alcohol. The evolutionary significance ofE9 desaturation being responsible for pheromone production in an Olethreutinae species is discussed.     

Use of a Reflectance Spectroscopy Accessory for Optical Characterization of ZnO-Bi(2)O(3)-TiO(2) Ceramics

The optical band-gap energy (E(g)) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. E(g) of the ceramic ZnO + xBi(2)O(3) + xTiO(2), where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. E(g) was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.     

Nox Gene Expression and Cytochemical Localization of Hydrogen Peroxide in Polyporus umbellatus Sclerotial Formation

The effect of temperature shift on Polyporus umbellatus sclerotial development was investigated. Micromorphology of the sclerotia was observed by using scanning electron microscopy (SEM). The cytochemical localization of H₂O₂ expressed as CeCl₃ deposition at the subcellular level was observed by using transmission electron microscopy (TEM). Nox gene expression in sclerotia and mycelia was detected by quantitative real-time PCR (qRT-PCR) analysis. In addition, superoxide dismutase (SOD) and catalase (CAT) specific activities increased during sclerotial development and decreased after the antioxidant diphenyleneiodonium (DPI) was used. Results indicated that the temperature shift treatment induced P. umbellatus sclerotial formation. Compared with the mycelia, the Nox gene was respectively upregulated by 10.577-, 30.984- and 25.469-fold in the sclerotia of SI, SD and SM stages respectively. During the sclerotial formation, H₂O₂ accumulation was observed in the cell walls or around the organelle membranes of the mycelial cells. The antioxidant DPI decreased the generation of H₂O₂ in mycelial cells. The specific activity of SOD and CAT levels was decreased significantly by DPI. The activity of the two antioxidant enzymes in the mycelia increased much more during sclerotial formation (p < 0.05). Oxidative stress was closely associated with sclerotial development in P. umbellatus induced by temperature shift treatment.     

Optimization of electrochemical properties of LiFePO4/C prepared by an aqueous solution method using sucrose

LiFePO₄ can be used as a positive electrode material for lithium-ion batteries by making composite with electrical conductive carbonaceous materials. In this study, LiFePO₄/C (carbon) composite was prepared by a soft chemistry route, in which sucrose was used as a carbon source of a low price. We tried to optimize a Li/(LiFePO₄/C) cell performance through changing synthetic conditions and discussed the factors affecting the electrochemical performances of the cell, such as the amount of the carbon source, synthetic temperature, gas flow rate of pyrolysis and the formation of secondary phases. It was found that the connection of the residual carbon and Fe₂P to LiFePO₄ particles and the amount of these two phases were important factors. In our experimental conditions, LiFePO₄/C including 9.72 wt.% of residual carbon, prepared at 800 °C for 12 h showed the highest reversible capacity and the best C rate performance among the synthesized materials; 130 mAh g⁻¹ at 10C rate and 50 °C.     

Synthesis and microstructure of (LaSr)MnO3 and (LaSr)FeO3 ceramics by a reaction-sintering process

(La_xSr_1−x)MnO₃ (LSMO) and (La_xSr_1−x)FeO₃ (LSFO) (x = 0.2–0.4) ceramics prepared by a simple and effective reaction-sintering process were investigated. Without any calcination involved, La₂O₃ and SrCO₃ were mixed with MnO₂ (LSMO) or Fe₂O₃ (LSFO) then pressed and sintered directly. LSMO and LSFO ceramics were obtained after 2 and 4 h sintering at 1350–1400 and 1200–1280 °C, respectively. Grain size decreased as La content increased in LSMO and LSFO ceramics.     

Effects of Zn or Ti substitution for Ni on the electrochemical properties of LiNiO2

LiNiO₂ and LiNi_1−yM_yO₂ (M = Zn and Ti, y = 0.005, 0.01, 0.025, 0.05, and 0.1) were synthesized with a solid-state reaction method by calcination at 750 °C for 30 h under oxygen stream after preheating at 450 °C for 5 h in air. LiNi_0.995Zn_0.005O₂ among the Zn-substituted samples and LiNi_0.995Ti_0.005O₂ among the Ti-substituted samples showed the best electrochemical properties. For similar values of y, LiNi_1−yTi_yO₂ had in general better electrochemical properties than LiNi_1−yZn_yO₂. Electrochemical properties seem to be closely related to R-factor but less related to I_0 0 3/I_1 0 4 value. In the FT-IR absorption spectra of LiNiO₂ and LiNi_1−yM_yO₂ (M = Zn and Ti, y = 0.005, 0.01, 0.025, 0.05 and 0.1), Li₂CO₃ was detected even if it is not observed from XRD pattern, with the samples LiNi_1−yZn_yO₂ (y = 0.05 and 0.1) showing Li₂ZnO₂ additionally. The smaller cation mixing of the Ti-substituted samples is considered to lead to their better electrochemical properties than the Zn-substituted samples.     

Adsorption and Reactions of CH2I2 on Clean and Oxygen-Modified Ag(111): a RAIRS and TPD Study

The surface chemistry of CH₂I₂ on Ag(111) in the presence and absence of pre-adsorbed O, produced by NO₂ adsorption at elevated temperature, has been examined using temperature-programmed desorption and reflection absorption infrared spectroscopy. There is good evidence for the formation of adsorbed methylene, CH₂(a), that reacts with another CH₂(a) to form and desorb ethylene, C₂H₄(g), in a reaction-limited process. Increasing the surface coverage of CH₂I₂ hinders both the dissociation and recombination processes indicated by the upward temperature shift in the formation of C₂H₄. Co-adsorbed O atoms strengthen the bonding of CH₂I₂ to the surface; the increased thermal stability is up to 60 K. The formation of C₂H₄ decreases with increasing amounts of pre-adsorbed O; the main reaction product is CH₂O produced in a reaction-limited process. CH₂O forms either on the chemisorbed or on the oxide phase with desorption peak temperatures of 225 and 270 K, respectively. The formation of gas-phase carbon dioxide suggests that a formate intermediate is involved in a secondary reaction pathway.     

SrCo0.8Fe0.2O3−δ sorbent for high-temperature production of oxygen-enriched carbon dioxide stream

Perovskite-type SrCo_0.8Fe_0.2O_3−δ (SCF) has been prepared by a liquid citrate method and used to produce O₂-CO₂ gas mixture for oxyfuel combustion. Oxygen is desorbed and an oxygen-enriched carbon dioxide stream is obtained when SCF is exposed in a carbon dioxide stream at high temperature. Oxygen is adsorbed when SCF is regenerated in an air stream. A carbonation-reaction mechanism for O₂-desorption has been identified with the evidences of XRD and TGA analysis. It is found that the theoretical oxygen sorption capacity decreases with the increase of temperature. The sorption kinetics over a temperature range of 700-900 °C has been examined by TGA experiment. Both desorption and sorption processes exhibit a high reaction rate in an initial stage followed by a slower rate in a second stage. It is difficult to reach the theoretical oxygen sorption capacity during the whole temperature range due to the slow oxygen desorption rate. Optimal temperatures for oxygen sorption and desorption processes are determined to be 900 and 850 °C, respectively. Multiple sorption and desorption cycles indicate that SCF sorbent has high reactivity and cyclic stability. Comparison with the reference La_0.1Sr_0.9Co_0.5Fe_0.5O_2.6 (LSCF) and Sr_0.5Ca_0.5Co_0.5Fe_0.5O_2.47 (SCCF) sorbents shows that SCF has faster carbonation reaction at high temperature, i.e., 850 and 900 °C, and much higher theoretical oxygen sorption capacities.     

Cobalt Alleviates GA-Induced Programmed Cell Death in Wheat Aleurone Layers via the Regulation of H2O2 Production and Heme Oxygenase-1 Expression

Heme oxygenase-1 (HO-1) and hydrogen peroxide (H₂O₂) are key signaling molecules that are produced in response to various environmental stimuli. Here, we demonstrate that cobalt is able to delay gibberellic acid (GA)-induced programmed cell death (PCD) in wheat aleurone layers. A similar response was observed when samples were pretreated with carbon monoxide (CO) or bilirubin (BR), two end-products of HO catalysis. We further observed that increased HO-1 expression played a role in the cobalt-induced alleviation of PCD. The application of HO-1-specific inhibitor, zinc protoporphyrin-IX (ZnPPIX), substantially prevented the increases of HO-1 activity and the alleviation of PCD triggered by cobalt. The stimulation of HO-1 expression, and alleviation of PCD might be caused by the initial H₂O₂ production induced by cobalt. qRT-PCR and enzymatic assays revealed that cobalt-induced gene expression and the corresponding activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), three enzymes that metabolize reactive oxygen species, were consistent with the H₂O₂ accumulation during GA treatment. These cobalt responses were differentially blocked by co-treatment with ZnPPIX. We therefore suggest that HO-1 functions in the cobalt-triggered alleviation of PCD in wheat aleurone layers, which is also dependent on the enhancement of the activities of antioxidant enzymes.     

MnOx/C composites as electrode materials II. Reduction of oxygen on bifunctional catalysts based on manganese oxides

MnO_x/C composites prepared by the reduction of KMnO₄ by active carbon black and doped with Ca(II), Mg(II), Ni(II), Bi(III), and Cr(III) ions were tested as catalysts of oxygen reduction in alkaline electrolyte. The polarisation curves were analysed by logarithmic wave analysis. MnO_x doped with the transition metal salts are slightly more active than those with Ca(II) and Mg(II).