Synthesis of Co/SiO2 hybrid nanocatalyst via twisted Co3Si2O5(OH)4 nanosheets for high-temperature Fischer-Tropsch reaction

A cobalt-silica hybrid nanocatalyst bearing small cobalt particles of diameter ～5 nm was prepared through a hydrothermal reaction and hydrogen reduction.The resulting material showed very high CO conversion (＞82％) and high hydrocarbon productivity (～1.0 gHc·g-1cat,·h-11) with high activity (～8.5 x 10-5 molco·g-1Co·S-1) in the Fischer-Tropsch synthesis reaction.     

Dynamic modeling of a proton exchange membrane fuel cell system with a shell-and-tube gas-to-gas membrane humidifier

The proton exchange membrane fuel cell (PEMFC) system with a shell-and-tube gas-to-gas membrane humidifier is considered to be a promising PEMFC system because of its energy-efficient operation. However, because the relative humidity of the dry air flowing into the stack depends on the stack exhaust air, this system can be unstable during transients. To investigate the dynamic behavior of the PEMFC system, a system model composed of a lumped dynamic model of an air blower, a two-dimensional dynamic model of a shell-and-tube gas-to-gas membrane humidifier, and a one-dimensional dynamic model of a PEMFC system is developed. Because the water management during transient of the PEMFC system is one of the key challenges, the system model is simulated at the step change of current. The variations in the PEMFC system characteristics are captured. To confirm the superiority of the system model, it is compared with the PEMFC component model during transients.     

Optimization of molten carbonate fuel cell (MCFC) and homogeneous charge compression ignition (HCCI) engine hybrid system for distributed power generation

In a previous study, a new hybrid system of molten carbonate fuel cell (MCFC) and homogeneous charge compression ignition (HCCI) engine was developed, where the HCCI engine replaces the catalytic burner and produces additional power by using the left-over heating values from the fuel cell stack. In the present study, to reduce the additional cost and footprint of the engine system in a hybrid configuration, the possibility of engine downsizing is investigated by using two strategies, i.e. the use of a turbocharger and the use of high geometric compression ratio for the engine design, both of which are to increase the density of the intake charge and thus the volumetric efficiency of the engine. Combining these two strategies, we suggest a new engine design with ∼60% of displacement volume of the original engine. In addition, operating strategies are developed to run the new hybrid system under part load conditions. It is successfully demonstrated that the system can operate down to 65% of the power level of the design point, while the system efficiency remains almost unchanged near 63%.     

Brief Review of Precipitated Iron-Based Catalysts for Low-Temperature Fischer–Tropsch Synthesis

Topics in Catalysis - Fischer–Tropsch synthesis (FTS) is a promising way to produce clean liquid fuels and high value-added chemicals from low-value carbon-containing resources such as coal,...     

An analysis of CH4/N2 rich biogas production, fuel treatment process and microturbine application

Biogas usually contains CH₄ and CO₂ as main components with the ratio of 6: 4, and its composition varies with wide range depending on digester conditions. In addition to concentration change of each constituent, biogas composition could be changed due to the variations in the organic matter treatment process. The aim of the study is to analyze the production and application to a microturbine system of CH₄/N₂ rich biogas produced from Gong-Ju wastewater treatment plant. CH₄/N₂ rich biogas is produced due to the internal wastewater recirculation. The internal wastewater recirculation is intended to enhance NO₃ ^? removal without additional carbon source input. As a result, the digester was shown to be the highest contributor for nitrogen removal and average CH₄ concentration was lowered compared to the typical biogas composition. Nitrate removal rate was influenced by the internal recirculation ratio. Content of N₂ has no effect on biogas clean-up system performance. Besides, adaptability of CH₄/N₂ rich biogas to microturbine was satisfactory with very low NOx and SO₂ concentration in microturbine exhaust gas. Influence of high N₂ concentration of biogas on NOx concentration was limited due to the low combustion temperature.     

Changes in the thermophysical properties of microcrystalline cellulose as function of carbonization temperature

Thermophysical properties of carbon materials derived from microcrystalline cellulose have been studied under vacuum and compared with earlier measurements conducted under nitrogen to better understand the influence of porosity, composition, microstructure, and atmosphere effects. The effective thermal conductivity in vacuum is lower than that observed in nitrogen primarily due to the conductivity of nitrogen gas. Radiation effects in both atmospheres were determined to be negligible. Reduction of thermal diffusivity in nitrogen was attributed to the effects of nitrogen gas phonon scattering. The trends for electrical and thermal property changes with structure are similar but not identical due to the differences in electron and phonon transport mechanisms.     

Disruption of vitamin D receptor-retinoid X receptor heterodimer formation following ras transformation of human keratinocytes

A partial resistance to the growth inhibitory influence of 1, 25-dihydroxyvitamin D3 is apparent when immortalized keratinocytes are transformed by the ras oncogene. The vitamin D receptor (VDR) was isolated, analyzed, and found to be identical in normal, immortalized, and ras-transformed keratinocytes. Subsequently, nuclear extracts from immortalized and ras-transformed keratinocytes were analyzed in gel mobility shift assays utilizing labeled vitamin D response elements or thyroid hormone response elements. A specific protein.DNA complex that was shown to contain VDR using an anti-VDR antibody was identified in both types of extracts; however, the addition of an anti-retinoid X receptor (RXR) antibody identified RXR in the complex of both normal and immortalized keratinocyte cell extracts, but not in ras-transformed keratinocytes. Furthermore, transfection of ras-transformed keratinocytes with wild-type human RXRalpha rescued VDR.RXR and thyroid hormone receptor.RXR complexes as demonstrated by a supershift in the presence of the anti-RXR antibody. Both cell lines were found to express RXRalpha message in equal amounts. Western blot analysis revealed that RXRalpha protein from ras-transformed keratinocytes was indistinguishable from that from immortalized keratinocytes and from control cells. These results suggest a causal relationship between resistance to the growth inhibitory influences of 1,25-dihydroxyvitamin D3 and disruption of the VDR.RXR complex in malignant keratinocytes.     

Gas separation by diffusion through silicone rubber capillaries

A study of pressure drop and separation of binary gas mixtures was conducted for gaseous diffusion cells, which consist of a bundle of silicone rubber capillary tubing. The Poiseuille equation, coupled together with the permeation equation, was used to describe the flow behavior of pure gases through the tubes. A successful correlation of pressure loss data for pure gases enabled us to model the flow of binary mixtures. Agreements were quite good between theoretical and experimental pressure losses for both pure gases and mixtures.Cascades of two and three stages were constructed out of several diffusion cells and separation experiments were carried out on these cascades. A comparison of theoretical and experimental cascade data is presented.     

Increase in water resistance of paperboard by coating with poly(lactide)

Poly(lactide) (PLA)‐coated paperboards (PB) were prepared, and the effect of coating for improving water resistance of paperboard used for corrugated box liners was tested. Surface of paperboards became smoother through PLA coating, and their thickness and weight of coating increased depending on the concentration of the coating solution. Tensile strength of paperboard decreased, while elongation at break (E) increased after PLA coating. All water barrier properties tested, such as water vapour permeability (WVP), water absorptiveness (WA) and contact angle (CA) of water drop, indicated that water resistance of paperboard was improved through surface coating with PLA. WVP decreased from 4.8 to 25.5 times, and WA decreased from 11.9 to 17.9 times depending on the PLA concentration. The increase in water resistance of PLA‐coated paperboards was due to the hydrophobicity of PLA, which was proven through CA measurement. CA determined by both static and dynamic methods demonstrated the increase in initial CA of PLA‐coated paperboards, indicating an increased hydrophobicity of surface. All test results indicated that the optimum concentration of coating solution for improving water resistance of paperboard was 3 w/v % of PLA soulution. Copyright © 2007 John Wiley & Sons, Ltd.     

Characterization of Y3 receptor-mediated synaptic inhibition by chimeric neuropeptide Y-peptide YY peptides in the rat brainstem

Archival material from primary and metastatic renal clear cell carcinomas of 25 patients was studied by comparative genomic hybridization. Copy number changes of entire chromosomes or chromosomal subregions were detected in 22 primary and 21 metastatic tumors. Copy number changes affected the following chromosomes in at least 20% of the 25 primary tumors (minimal common region given in parentheses): gains were noted for chromosomes 1 (1q21-->q23), 5 (5q31-->q34), 7 (7p), 8 (8q), 16 (16p), 17 (17q12-->qter), 19, and 22 (22q12-->qter); losses were revealed for chromosomes 3 (3p21-->pter), 8 (8p23-->pter), 14(14q21-->qter), and Y. The same chromosomal regions that were involved in primary renal clear cell carcinomas were also found in the respective metastatic tumors but with strikingly different frequencies for a few regions. Metastatic tumors showed a significantly higher frequency of complete or partial gains of the long arm of chromosome 1, in particular at 1q21-->q23 than primary tumors (16 cases versus 6 cases; P < 0.005). These data suggest a correlation of metastatic events in renal clear cell carcinomas with an increase in the copy number of genes located at 1q, in particular at 1q21-->q23. In contrast, the entire or partial loss of the short arm of chromosome 3 was significantly less frequent in metastatic tumors (8 cases versus 15 cases; P < 0.025). The validity of 1q and 3p copy number changes detected by comparative genomic hybridization was confirmed by interphase cytogenetics with region-specific yeast artificial chromosomes to paraffin-embedded tumor tissue sections.