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02303 A comparative study of concrete properties using coconut shell and palm kernel shell as coarse aggregates
13 Alternative energy supplies (biofuels and bioconversion energy) performed at high temperature on a bauxite-based refractory, which is used in steel ladle linings. It is shown that for this ceramic few material parameters are sufficient to account for major differences of behaviour observed in compression tests and three-point bend tests.
06/02297 Plasma-sprayed glass-ceramic coatings on ceramic tiles: microstructure, chemical resistance and mechanical properties Bolelli, G. et al. Journal o/" the European Ceramic Society, 2005, 25, (11), 1835 1853. This article reports the characterization and optimization of glassceramic coatings plasma-sprayed on traditional ceramic substrates, dealing with microstructures, chemical resistance, and superficial mechanical properties. A CaO-ZrOz-SiOz (CZS) frit, capable of complete crystallization after proper thermal treatment, has been employed: due to its refractory nature, its firing temperature in a traditional process would be unbearable for common substrates. The frit was plasma-sprayed onto ceramic tiles and a post-process thermal treatment has been developed in order to sinter and crystallize the coating, employing much lower temperatures than a traditional ceramic firing cycle. The microstructure of both as-sprayed and treated coatings has been evaluated with SEM and EDS, acid resistance tests have been performed. Vickers microhardness, superficial fracture toughness, deep abrasion resistance, elastic modulus and coating adhesion have been evaluated. Unglazed stoneware and an industrial glaze were also tested for comparison and an experiment was made to produce a CZSbased glaze to ascertain the inadequacy of traditional firing. Assprayed coatings have a typical plasma-spraying defective microstructure, but a thermal treatment with 30' isotherm at 850°C plus 15' isotherm at 1050°C allows good densification, excellent adhesion and complete crystallization, with formation of wollastonite-2M and many small Ca2ZrSi4012 grains. Thus, the coating outperforms stoneware by 50% in abrasion resistance, possessing higher fracture toughness, thanks to the continuous crack deflections due to the numerous crystals. Fracture toughness appears to be the property most correlated to abrasion resistance, because brittle fracture is the dominant abrasion mechanism. Hardness and elastic modulus reflect quite well the coating inner cohesion. Treated coatings porosity is lower than industrial glazes and stoneware.
06102298 Positronium formation in sol-gel-prepared silicabased glasses: temperature and positron-irradiation effect Djourelov, N. et al. Radiation Physics and Chemistry, 2005, 72, (6), 723729. Silica, titania-silica, and zirconia-siiica samples were studied at room temperature (RT) and low temperature (LT ~50 K) by means of positron annihilation lifetime spectroscopy. It was confirmed that the samples were composed of oxide particles with finer pores dispersed within them and larger pores between the particles. The effect of e +irradiation during the measurements was checked. The o-Ps lifetime originating from the larger pores was quenched at LT for all of the samples. For the zirconia-silica sample, this effect was observed even at RT. Quenching is an indication of orthopara positronium conversion on paramagnetic centres formed due to e ~-irradiation. These centres appear to be the reason why the longest lifetime as a function of the temperature does not follow the Goworek-Gidley model at temperatures below RT. Above RT, the Goworek-Gidley model fits well with the experimental values for the longest lifetime.
06/02299 Preparation and characterization of tubular ceramic membranes for treatment of oil emulsions Benito, J. M. et al. Journal of the European Ceramic Society, 2005, 25, (113, 1895-1903. Multilayer membranes for the treatment of oily waters have been prepared from ceramic materials. Alumina and cordierite supports have been prepared as well as c~-AI203 intermediate layers. 7-A1203 top layers with very high porosities were prepared by the sol-gel method and a detailed study has been performed because of the importance of this layer in the filtration process. A structural study by means of nitrogen adsorption-desorption, nitrogen permeability,and scanning electron microscopy has been carried out on unsupported and supported top layers membranes. The effect of the sol concentration and calcination temperature on the structure of the membrane was studied to get an appropriate pore size and porosity. Also, the necessary amount of PVA as binder/plastizier to get defect-free membranes was investigated. Top-layer membranes in tubular configuration with an average pore diameter around 4 nm and porosities of 72% have been obtained.
06/02300 Properties of concrete made with recycled crushed glass at elevated temperatures Terro, M. J. Building and Environment, 2006, 41, (5), 633-639. The effect of replacement of fine and coarse aggregates with recycled glass on the fresh and hardened properties of Portland cement concrete at ambient and elevated temperatures is studied. Percentages
350
Fuel and Energy Abstracts September 2006
of replacement of 0-100% of aggregates with fine waste glass (FWG), coarse waste glass (CWG), and fine and coarse waste glass (FCWG) were considered. Soda-lime glass used for bottles was washed and crushed to fine and coarse aggregate sizes for use in the concrete mixes. Samples were cured under 95% RH at room temperatures (2022°C), heated in the oven to the desired temperatures, allowed to cool to ambient temperatures, and then tested for their residual compressive strength. The compressive strength of the concrete samples made with waste glass was measured at temperatures up to 700°C. Moreover, the effect of the percentages of replacement with recycled glass on the slump values and initial and final setting time of concrete has also been measured. The results of this study showed that the compressive strength of concrete made with RG decreases up to 20% of its original value with increasing temperatures up to 700°C. In general, concretes made with 10% aggregates replacement with FWG, CWG and FCWG had better properties in the fresh and hardened states at ambient and high temperatures than those with larger replacement. Concretes made with FWG aggregates had higher compressive strengths than those made with CWG and FCWG at ambient and elevated temperatures.
06/02301 The effects of atmospheric exposure on the fracture properties of polymer concrete Reis, J. M. L. and Ferreira, A. J. M. Building and Environment, 2006, 41, (3), 262 267. In this experiment the effect of atmospheric exposure of epoxy and fibre-reinforced epoxy polymer concrete was investigated to evaluate its fracture properties, such as stress intensity factor, K~, and fracture energy, Gr. The deterioration and structural performance of polymer concrete were investigated in a real situation of exposure during a year period and compared the same formulation in laboratory conditions. The relationship between year period, exposure time and load-bearing capacity of deteriorated polymer concrete is studied and fracture mechanics of the specimens are discussed. From the tests results and discussion it is clear that the material studied, polymer concrete, suffers a high deterioration when subjected to aggressive environments.
06/02302 Thermal conductivity degradation of ceramic materials due to low temperature, low dose neutron irradiation Snead, L. L. et al. Journal of Nuclear 3,laterials, 2005, 340, (2-3), 187202. The thermal conductivity degradation due to low-temperature neutron irradiation is studied and quantified in terms of thermal resistance terms. Neutron irradiation is assumed to have no effect on umklapp scattering. A theoretical model is presented to quantify the relative phonon-scattering effectiveness of the three dominant defect types produced by neutron irradiation: point defects, dislocation loops and voids. Several commercial ceramics have been irradiated with fission reactor fast neutrons at low temperatures to produce defects. Materials include silicon carbide, sapphire, polycrystalline alumina, aluminum nitride, silicon nitride, beryllium oxide, and a carbon fibre composite. The neutron dose corresponded to 0.001 and 0.01 displacements per atom (dpa) for a ~60°C irradiation and 0.01 and 0.1 dpa for a ~300°C irradiation. Substantial thermal conductivity degradation occurred in all of the materials except BeO following irradiation at 60:C to a dose of only 0.001 dpa. The data are discussed in terms of the effective increase in thermal resistance caused by the different irradiation conditions. Evidence for significant point defect mobility during irradiation at 60 and 300°C was obtained for all of the ceramics. The thermal stability of the radiation defects was investigated by isochronal annealing up to 1050°C.
13
ALTERNATIVE ENERGY SUPPLIES Biofuels and bioconversion energy
06/02303 A comparative study of concrete properties using coconut shell and palm kernel shell as coarse aggregates Olanipekun, E. A. et al. Building and Environment, 2006, 41, (3), 297301. The high cost of conventional building materials is a major factor affecting housing delivery in Nigeria. This has necessitated research into alternative materials of construction. This paper presents the results of an investigation carried out on the comparative cost analysis and strength characteristics of concrete produced using crushed,
13 Alternative energy supplies (biofuels and bioconversion energy) granular coconut and palm kernel shells as substitutes for conventional coarse aggregate in gradation of 0%, 25%, 50%, 75% and 100%. Two mix ratios (1:1:2 and 1:2:4) were used. A total of 320 cubes of size 100 × 100 x 100 m m were cast, tested and their physical and mechanical properties determined. The results of the tests showed that the compressive strength of the concrete decreased as the percentage of the shells increased in the two mix ratios. However, concrete obtained from coconut shells exhibited a higher compressive strength than palm kernel shell concrete in the two mix proportions. The results also indicated cost reduction of 30% and 42% for concrete produced from coconut shells and palm kernel shells, respectively. Considering the strength/economy ratio, it was concluded that coconut shells were more suitable than palm kernel shells when used as substitute for conventional aggregates in concrete production.
06/02304
Biochemistry of hydrogen metabolism in
Chlamydomonas reinhardtii wild type and a Rubisco-less mutant White, A. L. and Melis, A. International Journal o/" Itydrogen Energy, 2006, 31, (4), 455-464. Sulfate nutrient-deprivation in Chlamydomonas rei~zhardtii brings about prompt degradation of Rubisco and a concomitant substantial accumulation of starch. These changes precede hydrogen (H2) photoevolution by the cells. The cause-and-effect relationship between Rubisco loss, starch accumulation and subsequent H;-photoevolution in C. reinhardtii, and the role of illumination for these changes to occur, was investigated in this work. A Rubisco-less and acetaterequiring mutant of C. reinhardtii (CC2653) was employed as a tool in this investigation and compared to the wild type (WT) in terms of protein and starch metabolic flux and H2-evolution upon sulfur deprivation. Results showed a prompt Rubisco degradation and concomitant 10-fold starch accumulation in the WT in the light, which was completed within 48 h of S-deprivation. This was followed by a regulated starch degradation and concomitant H,-photoevolution, which lasted for up to 120 h in S-deprivation. This massive flux of primary metabolites (protein and starch) did not occur in the dark in the WT, suggesting a strictly light-dependent and integrated process in metabolite rearrangement and H2-photoevolution in C. reinhardtii. The Rubisco-tess CC2653 mutant failed to accumulate starch upon Sdeprivation in the light or dark and also failed to evolve H2 gas. These results suggested a temporal cause-and-effect relationship between the light-dependent catabolism of Rubisco and starch accumulation, and the subsequent ability of the cell to perform a light-dependent starch degradation and H2-photoevolution. The regulated starch breakdown in the light apparently provides the endogenous substrate that supports H2-evolution, both by feeding electrons into the plastoquinone pool in chloroplasts, and indirectly by sustaining mitochondrial respiration for the maintenance of anaerobiosis in the cell.
06•02305 Bringing solar home systems to rural El Salvador: lessons for small NGOs Balint, P. J. Energy Policy, 2006, 34, (6l, 721 729. This paper presents the results of case studies examining two independent projects that worked to bring solar home systems (SHSs) to isolated communities in El Salvador. Both projects were implemented by small non-governmental organizations (NGOs) that did not have prior experience with SHSs. One project was market-based: families were given the opportunity to purchase the systems at going prices. The other was donor-based: residents were provided the equipment in return for their agreement to cooperate in local environmental protection efforts. Results of a comparative analysis support several conclusions. (1) For small NGOs, the promotion of markets is appealing because of the potential for financial sustainability; yet a reliance on markets may also heighten complexity and increase opportunities for failure. (2) In implementation of marketbased projects, all stakeholders, including potential consumers, private-sector service providers, and the staff of NGOs acting as project managers, will face pressures to modify and adapt their attitudes and behaviours. (3) Alternative models for small-scale projects that integrate market-based and donor-based design features deserve consideration.
06•02306 Characterization and quantification of biomarkers from biomass burning at a recent wildfire site in Northern Alberta, Canada Otto, A. et al. Applied Geoc'hemistry, 2006, 21, (1), 166-183. The composition of organic matter (OM) in pine vegetation and soil samples from a pine forest which was charred by a wildfire was analysed using solid-state nuclear magnetic resonance (13C NMR) and gas chromatography-mass spectrometry (GC-MS) of solvent extracts to study the effects of thermal alteration on soil organic matter (SOM). The NMR data revealed the presence of unaltered biomolecules (cellulose, proteins) and low contents of aromatic C (15%) in the charred pine wood and cones while the charred soil samples exhibited higher contents of aromatic C (39-56%). The solvent extraction of
charred and uncharred plant and soil samples yielded diterpenoids, triterpenoids, steroids, a series of aliphatic lipids, phenols and carbohydrates indicating the predominant input of higher plant OM and minor contributions from micro-organisms and/or fauna. The lower yield of solvent extractable aliphatic lipids in the charred samples versus the uncharted samples suggests that these compounds are thermally degraded during a wildfire. Molecular markers for the burning of cellulose (levoglucosan, mannosan, galactosan) were detected in all charred samples. The comparison of charred and uncharred samples allowed the identification of unaltered pine derived biomolecules and their thermal alteration products in the charred samples. Terpenoid and steroid biomolecules were in part altered during incomplete combustion to aromatic, unsaturated and polar derivatives ('pyromolecules') that still retained the characteristic skeleton of their precursors. Since some of the polar degradation products found in the charred soils can be generated either from thermal or microbial degradation, the aromatic and unsaturated hydrocarbon products are preferred as molecular markers for SOM burning. Ratios of biological precursors to aromatic (diterpenoids) or unsaturated products (steroids) indicate that the cyclic lipids in the pine wood and the soil surface horizon were highly altered. In conclusion, the solvent extractable lipids and carbohydrates in charred SOM are valuable, source-specific molecular markers for the burning of plant biomass and for tracing the biogeochemistry of charred residues in soils.
06/02307 Co-firing of sugar cane bagasse with rice husk in a conical fluidized-bed combustor Kuprianov, V. I. et al. Fuel, 2006, 85, (4), 434-442. This paper presents experimental results on co-firing of 'as-received" sugar cane bagasse and rice husk in a conical fluidized-bed combustor (FBC) using silica sand as the bed material. Axial temperature, 02, CO2, CO and NO concentration profiles in the conical FBC operated at 82.5-82.8 kg/h fuel feed rate and various values of excess air (of about 40, 60, 80 and 100%) for different rice husk energy fractions (of 0.60, 0.85 and 1.0) are discussed. The bed temperature, CO and NO emissions from the combustor, as well as the heat losses and combustion efficiency, are also provided for the above operating conditions. The axial temperature profiles in the conical FBC were almost independent of excess air but noticeably affected by the rice husk energy fraction. The CO emissions were found to reduce for higher values of excess air and rice husk energy fractions. Meanwhile, the NO concentrations at all the points over the combustor volume and, accordingly, NO emissions from the reactor increased with higher excess air and energy contributions by rice husk. The co-firing of these fuels in the conical FBC at the rice husk energy fractions greater than 0.6 resulted in the sustainable combustion, with 95-96% combustion efficiency, and lower NO emissions compared with those for firing pure rice husk. Through co-firing with rice husk, an effective use of 'asreceived' sugar cane bagasse becomes feasible for energy conversion in the fluidized-bed combustion systems.
06102308 Comparison of the generation of oil by the extraction and the hydropyrolysis of biomass Onay, O. et al. Fuel, 2006, 85, (13), 382-392. This paper discusses the maximization of the yields of useful bio-oils generated from seeds and nut-shells both by extraction and by hydropyrolysis. The formation and the composition of the bio-oils are also discussed. Powdered (<0.25 mm diameter) rapeseed, linseed and safflower seed and hazel nut and walnut shells, that is, fresh precursors of liptinite, have been characterized by their elemental analyses, infrared and N M R spectra. Bio-oils obtained both by extraction and by slow hydropyrolysis to 520°C at moderate pressure in the presence of ammonium dioxydithiomolybdate have been compared by the same analyses and by gas chromatography. Consistent with a previous work on this subject, extraction of the seeds with organic solvents, including diesel oil, gave yields of up to 40% together with an uninteresting residue. However, subsequent saponification of the residues gave further yields of oil. Hydropyrolysis removed oxygen from the seeds as water and as oxides of carbon to generate bio-oil in yields of up to 75%. Whereas little oil could be extracted from the nut-shells, hydropyrolysis gave oil yields of approximately 40%. Some char was also formed, suggesting that optimization of the hydropyrolysis might give even larger yields of oil.
06•02309 Effect of changes in the level of light harvesting complexes of Rhodobacter sphaeroides on the photoheterotrophic production of hydrogen Kim, E.-J. et al. International Journal of Hydrogen Energy, 2006, 31, (4), 531-538. Increase in levels of photosynthetic spectral complexes by maintaining the plasmids harboring D N A encoding puhA, pufBA, or pucBAC in trans in Rhodobacter sphaeroides resulted in decrease of the photoheterotrophic production of H2. However, removal of B875 or B800 850 light-harvesting (LH) complexes affected H2 production differently.
Fuel and Energy Abstracts September 2006
351
06/02297 Plasma-sprayed glass-ceramic coatings on ceramic tiles: microstructure, chemical resistance and mechanical properties Bolelli, G. et al. Journal o/" the European Ceramic Society, 2005, 25, (11), 1835 1853. This article reports the characterization and optimization of glassceramic coatings plasma-sprayed on traditional ceramic substrates, dealing with microstructures, chemical resistance, and superficial mechanical properties. A CaO-ZrOz-SiOz (CZS) frit, capable of complete crystallization after proper thermal treatment, has been employed: due to its refractory nature, its firing temperature in a traditional process would be unbearable for common substrates. The frit was plasma-sprayed onto ceramic tiles and a post-process thermal treatment has been developed in order to sinter and crystallize the coating, employing much lower temperatures than a traditional ceramic firing cycle. The microstructure of both as-sprayed and treated coatings has been evaluated with SEM and EDS, acid resistance tests have been performed. Vickers microhardness, superficial fracture toughness, deep abrasion resistance, elastic modulus and coating adhesion have been evaluated. Unglazed stoneware and an industrial glaze were also tested for comparison and an experiment was made to produce a CZSbased glaze to ascertain the inadequacy of traditional firing. Assprayed coatings have a typical plasma-spraying defective microstructure, but a thermal treatment with 30' isotherm at 850°C plus 15' isotherm at 1050°C allows good densification, excellent adhesion and complete crystallization, with formation of wollastonite-2M and many small Ca2ZrSi4012 grains. Thus, the coating outperforms stoneware by 50% in abrasion resistance, possessing higher fracture toughness, thanks to the continuous crack deflections due to the numerous crystals. Fracture toughness appears to be the property most correlated to abrasion resistance, because brittle fracture is the dominant abrasion mechanism. Hardness and elastic modulus reflect quite well the coating inner cohesion. Treated coatings porosity is lower than industrial glazes and stoneware.
06102298 Positronium formation in sol-gel-prepared silicabased glasses: temperature and positron-irradiation effect Djourelov, N. et al. Radiation Physics and Chemistry, 2005, 72, (6), 723729. Silica, titania-silica, and zirconia-siiica samples were studied at room temperature (RT) and low temperature (LT ~50 K) by means of positron annihilation lifetime spectroscopy. It was confirmed that the samples were composed of oxide particles with finer pores dispersed within them and larger pores between the particles. The effect of e +irradiation during the measurements was checked. The o-Ps lifetime originating from the larger pores was quenched at LT for all of the samples. For the zirconia-silica sample, this effect was observed even at RT. Quenching is an indication of orthopara positronium conversion on paramagnetic centres formed due to e ~-irradiation. These centres appear to be the reason why the longest lifetime as a function of the temperature does not follow the Goworek-Gidley model at temperatures below RT. Above RT, the Goworek-Gidley model fits well with the experimental values for the longest lifetime.
06/02299 Preparation and characterization of tubular ceramic membranes for treatment of oil emulsions Benito, J. M. et al. Journal of the European Ceramic Society, 2005, 25, (113, 1895-1903. Multilayer membranes for the treatment of oily waters have been prepared from ceramic materials. Alumina and cordierite supports have been prepared as well as c~-AI203 intermediate layers. 7-A1203 top layers with very high porosities were prepared by the sol-gel method and a detailed study has been performed because of the importance of this layer in the filtration process. A structural study by means of nitrogen adsorption-desorption, nitrogen permeability,and scanning electron microscopy has been carried out on unsupported and supported top layers membranes. The effect of the sol concentration and calcination temperature on the structure of the membrane was studied to get an appropriate pore size and porosity. Also, the necessary amount of PVA as binder/plastizier to get defect-free membranes was investigated. Top-layer membranes in tubular configuration with an average pore diameter around 4 nm and porosities of 72% have been obtained.
06/02300 Properties of concrete made with recycled crushed glass at elevated temperatures Terro, M. J. Building and Environment, 2006, 41, (5), 633-639. The effect of replacement of fine and coarse aggregates with recycled glass on the fresh and hardened properties of Portland cement concrete at ambient and elevated temperatures is studied. Percentages
350
Fuel and Energy Abstracts September 2006
of replacement of 0-100% of aggregates with fine waste glass (FWG), coarse waste glass (CWG), and fine and coarse waste glass (FCWG) were considered. Soda-lime glass used for bottles was washed and crushed to fine and coarse aggregate sizes for use in the concrete mixes. Samples were cured under 95% RH at room temperatures (2022°C), heated in the oven to the desired temperatures, allowed to cool to ambient temperatures, and then tested for their residual compressive strength. The compressive strength of the concrete samples made with waste glass was measured at temperatures up to 700°C. Moreover, the effect of the percentages of replacement with recycled glass on the slump values and initial and final setting time of concrete has also been measured. The results of this study showed that the compressive strength of concrete made with RG decreases up to 20% of its original value with increasing temperatures up to 700°C. In general, concretes made with 10% aggregates replacement with FWG, CWG and FCWG had better properties in the fresh and hardened states at ambient and high temperatures than those with larger replacement. Concretes made with FWG aggregates had higher compressive strengths than those made with CWG and FCWG at ambient and elevated temperatures.
06/02301 The effects of atmospheric exposure on the fracture properties of polymer concrete Reis, J. M. L. and Ferreira, A. J. M. Building and Environment, 2006, 41, (3), 262 267. In this experiment the effect of atmospheric exposure of epoxy and fibre-reinforced epoxy polymer concrete was investigated to evaluate its fracture properties, such as stress intensity factor, K~, and fracture energy, Gr. The deterioration and structural performance of polymer concrete were investigated in a real situation of exposure during a year period and compared the same formulation in laboratory conditions. The relationship between year period, exposure time and load-bearing capacity of deteriorated polymer concrete is studied and fracture mechanics of the specimens are discussed. From the tests results and discussion it is clear that the material studied, polymer concrete, suffers a high deterioration when subjected to aggressive environments.
06/02302 Thermal conductivity degradation of ceramic materials due to low temperature, low dose neutron irradiation Snead, L. L. et al. Journal of Nuclear 3,laterials, 2005, 340, (2-3), 187202. The thermal conductivity degradation due to low-temperature neutron irradiation is studied and quantified in terms of thermal resistance terms. Neutron irradiation is assumed to have no effect on umklapp scattering. A theoretical model is presented to quantify the relative phonon-scattering effectiveness of the three dominant defect types produced by neutron irradiation: point defects, dislocation loops and voids. Several commercial ceramics have been irradiated with fission reactor fast neutrons at low temperatures to produce defects. Materials include silicon carbide, sapphire, polycrystalline alumina, aluminum nitride, silicon nitride, beryllium oxide, and a carbon fibre composite. The neutron dose corresponded to 0.001 and 0.01 displacements per atom (dpa) for a ~60°C irradiation and 0.01 and 0.1 dpa for a ~300°C irradiation. Substantial thermal conductivity degradation occurred in all of the materials except BeO following irradiation at 60:C to a dose of only 0.001 dpa. The data are discussed in terms of the effective increase in thermal resistance caused by the different irradiation conditions. Evidence for significant point defect mobility during irradiation at 60 and 300°C was obtained for all of the ceramics. The thermal stability of the radiation defects was investigated by isochronal annealing up to 1050°C.
13
ALTERNATIVE ENERGY SUPPLIES Biofuels and bioconversion energy
06/02303 A comparative study of concrete properties using coconut shell and palm kernel shell as coarse aggregates Olanipekun, E. A. et al. Building and Environment, 2006, 41, (3), 297301. The high cost of conventional building materials is a major factor affecting housing delivery in Nigeria. This has necessitated research into alternative materials of construction. This paper presents the results of an investigation carried out on the comparative cost analysis and strength characteristics of concrete produced using crushed,
13 Alternative energy supplies (biofuels and bioconversion energy) granular coconut and palm kernel shells as substitutes for conventional coarse aggregate in gradation of 0%, 25%, 50%, 75% and 100%. Two mix ratios (1:1:2 and 1:2:4) were used. A total of 320 cubes of size 100 × 100 x 100 m m were cast, tested and their physical and mechanical properties determined. The results of the tests showed that the compressive strength of the concrete decreased as the percentage of the shells increased in the two mix ratios. However, concrete obtained from coconut shells exhibited a higher compressive strength than palm kernel shell concrete in the two mix proportions. The results also indicated cost reduction of 30% and 42% for concrete produced from coconut shells and palm kernel shells, respectively. Considering the strength/economy ratio, it was concluded that coconut shells were more suitable than palm kernel shells when used as substitute for conventional aggregates in concrete production.
06/02304
Biochemistry of hydrogen metabolism in
Chlamydomonas reinhardtii wild type and a Rubisco-less mutant White, A. L. and Melis, A. International Journal o/" Itydrogen Energy, 2006, 31, (4), 455-464. Sulfate nutrient-deprivation in Chlamydomonas rei~zhardtii brings about prompt degradation of Rubisco and a concomitant substantial accumulation of starch. These changes precede hydrogen (H2) photoevolution by the cells. The cause-and-effect relationship between Rubisco loss, starch accumulation and subsequent H;-photoevolution in C. reinhardtii, and the role of illumination for these changes to occur, was investigated in this work. A Rubisco-less and acetaterequiring mutant of C. reinhardtii (CC2653) was employed as a tool in this investigation and compared to the wild type (WT) in terms of protein and starch metabolic flux and H2-evolution upon sulfur deprivation. Results showed a prompt Rubisco degradation and concomitant 10-fold starch accumulation in the WT in the light, which was completed within 48 h of S-deprivation. This was followed by a regulated starch degradation and concomitant H,-photoevolution, which lasted for up to 120 h in S-deprivation. This massive flux of primary metabolites (protein and starch) did not occur in the dark in the WT, suggesting a strictly light-dependent and integrated process in metabolite rearrangement and H2-photoevolution in C. reinhardtii. The Rubisco-tess CC2653 mutant failed to accumulate starch upon Sdeprivation in the light or dark and also failed to evolve H2 gas. These results suggested a temporal cause-and-effect relationship between the light-dependent catabolism of Rubisco and starch accumulation, and the subsequent ability of the cell to perform a light-dependent starch degradation and H2-photoevolution. The regulated starch breakdown in the light apparently provides the endogenous substrate that supports H2-evolution, both by feeding electrons into the plastoquinone pool in chloroplasts, and indirectly by sustaining mitochondrial respiration for the maintenance of anaerobiosis in the cell.
06•02305 Bringing solar home systems to rural El Salvador: lessons for small NGOs Balint, P. J. Energy Policy, 2006, 34, (6l, 721 729. This paper presents the results of case studies examining two independent projects that worked to bring solar home systems (SHSs) to isolated communities in El Salvador. Both projects were implemented by small non-governmental organizations (NGOs) that did not have prior experience with SHSs. One project was market-based: families were given the opportunity to purchase the systems at going prices. The other was donor-based: residents were provided the equipment in return for their agreement to cooperate in local environmental protection efforts. Results of a comparative analysis support several conclusions. (1) For small NGOs, the promotion of markets is appealing because of the potential for financial sustainability; yet a reliance on markets may also heighten complexity and increase opportunities for failure. (2) In implementation of marketbased projects, all stakeholders, including potential consumers, private-sector service providers, and the staff of NGOs acting as project managers, will face pressures to modify and adapt their attitudes and behaviours. (3) Alternative models for small-scale projects that integrate market-based and donor-based design features deserve consideration.
06•02306 Characterization and quantification of biomarkers from biomass burning at a recent wildfire site in Northern Alberta, Canada Otto, A. et al. Applied Geoc'hemistry, 2006, 21, (1), 166-183. The composition of organic matter (OM) in pine vegetation and soil samples from a pine forest which was charred by a wildfire was analysed using solid-state nuclear magnetic resonance (13C NMR) and gas chromatography-mass spectrometry (GC-MS) of solvent extracts to study the effects of thermal alteration on soil organic matter (SOM). The NMR data revealed the presence of unaltered biomolecules (cellulose, proteins) and low contents of aromatic C (15%) in the charred pine wood and cones while the charred soil samples exhibited higher contents of aromatic C (39-56%). The solvent extraction of
charred and uncharred plant and soil samples yielded diterpenoids, triterpenoids, steroids, a series of aliphatic lipids, phenols and carbohydrates indicating the predominant input of higher plant OM and minor contributions from micro-organisms and/or fauna. The lower yield of solvent extractable aliphatic lipids in the charred samples versus the uncharted samples suggests that these compounds are thermally degraded during a wildfire. Molecular markers for the burning of cellulose (levoglucosan, mannosan, galactosan) were detected in all charred samples. The comparison of charred and uncharred samples allowed the identification of unaltered pine derived biomolecules and their thermal alteration products in the charred samples. Terpenoid and steroid biomolecules were in part altered during incomplete combustion to aromatic, unsaturated and polar derivatives ('pyromolecules') that still retained the characteristic skeleton of their precursors. Since some of the polar degradation products found in the charred soils can be generated either from thermal or microbial degradation, the aromatic and unsaturated hydrocarbon products are preferred as molecular markers for SOM burning. Ratios of biological precursors to aromatic (diterpenoids) or unsaturated products (steroids) indicate that the cyclic lipids in the pine wood and the soil surface horizon were highly altered. In conclusion, the solvent extractable lipids and carbohydrates in charred SOM are valuable, source-specific molecular markers for the burning of plant biomass and for tracing the biogeochemistry of charred residues in soils.
06/02307 Co-firing of sugar cane bagasse with rice husk in a conical fluidized-bed combustor Kuprianov, V. I. et al. Fuel, 2006, 85, (4), 434-442. This paper presents experimental results on co-firing of 'as-received" sugar cane bagasse and rice husk in a conical fluidized-bed combustor (FBC) using silica sand as the bed material. Axial temperature, 02, CO2, CO and NO concentration profiles in the conical FBC operated at 82.5-82.8 kg/h fuel feed rate and various values of excess air (of about 40, 60, 80 and 100%) for different rice husk energy fractions (of 0.60, 0.85 and 1.0) are discussed. The bed temperature, CO and NO emissions from the combustor, as well as the heat losses and combustion efficiency, are also provided for the above operating conditions. The axial temperature profiles in the conical FBC were almost independent of excess air but noticeably affected by the rice husk energy fraction. The CO emissions were found to reduce for higher values of excess air and rice husk energy fractions. Meanwhile, the NO concentrations at all the points over the combustor volume and, accordingly, NO emissions from the reactor increased with higher excess air and energy contributions by rice husk. The co-firing of these fuels in the conical FBC at the rice husk energy fractions greater than 0.6 resulted in the sustainable combustion, with 95-96% combustion efficiency, and lower NO emissions compared with those for firing pure rice husk. Through co-firing with rice husk, an effective use of 'asreceived' sugar cane bagasse becomes feasible for energy conversion in the fluidized-bed combustion systems.
06102308 Comparison of the generation of oil by the extraction and the hydropyrolysis of biomass Onay, O. et al. Fuel, 2006, 85, (13), 382-392. This paper discusses the maximization of the yields of useful bio-oils generated from seeds and nut-shells both by extraction and by hydropyrolysis. The formation and the composition of the bio-oils are also discussed. Powdered (<0.25 mm diameter) rapeseed, linseed and safflower seed and hazel nut and walnut shells, that is, fresh precursors of liptinite, have been characterized by their elemental analyses, infrared and N M R spectra. Bio-oils obtained both by extraction and by slow hydropyrolysis to 520°C at moderate pressure in the presence of ammonium dioxydithiomolybdate have been compared by the same analyses and by gas chromatography. Consistent with a previous work on this subject, extraction of the seeds with organic solvents, including diesel oil, gave yields of up to 40% together with an uninteresting residue. However, subsequent saponification of the residues gave further yields of oil. Hydropyrolysis removed oxygen from the seeds as water and as oxides of carbon to generate bio-oil in yields of up to 75%. Whereas little oil could be extracted from the nut-shells, hydropyrolysis gave oil yields of approximately 40%. Some char was also formed, suggesting that optimization of the hydropyrolysis might give even larger yields of oil.
06•02309 Effect of changes in the level of light harvesting complexes of Rhodobacter sphaeroides on the photoheterotrophic production of hydrogen Kim, E.-J. et al. International Journal of Hydrogen Energy, 2006, 31, (4), 531-538. Increase in levels of photosynthetic spectral complexes by maintaining the plasmids harboring D N A encoding puhA, pufBA, or pucBAC in trans in Rhodobacter sphaeroides resulted in decrease of the photoheterotrophic production of H2. However, removal of B875 or B800 850 light-harvesting (LH) complexes affected H2 production differently.
Fuel and Energy Abstracts September 2006
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