Nanocrystalline Ferrihydrite-Based Catalysts for Fischer-Tropsch Synthesis: Part I. Reduction and Carburization Behavior.

Temperature-programmed reduction using H2 (H2-TPR) and CO (CO-TPR) was carried out to investigate the reduction and carburization behavior of nanocrystalline ferrihydrite-based Fe/Cu/K/SiO2 catalysts for use in Fischer-Tropsch synthesis (FTS). Unlike pure ferrihydrite, the ferrihydrite-based catalysts did not pass through the intermediate decomposition step of ferrihydrite (Fe9O2(OH)23) into hematite (a-Fe2O3) as they were reduced into magnetite (Fe3O4). This is attributed to the enhanced thermal stability induced by SiO2. For the ferrihydrite-based catalysts, the reduction of ferrihydrite into magnetite occurred in two stages because the reduction promoter, Cu, is not homogeneously distributed on the catalyst surfaces. The Cu-rich sites are likely to be reduced in the first stage, and the Cu-lean sites may be reduced in the second stage. After the ferrihydrite is reduced to magnetite, the reduction process of magnetite was similar to that for conventional hematite-based FTS catalysts: 'magnetite --> metallic iron' and 'magnetite --> wüstite (FeO) or fayalite (Fe2SiO4) --> metallic iron' in the H2 atmosphere; 'magnetite --> iron carbides' in the CO atmosphere.

A Facile Synthesis of SiO2@Co/mSiO2 Egg-Shell Nanoreactors for Fischer-Tropsch Reaction.

Recently, a convenient melt-infiltration method, using a hydrated metal salt with porous support, was developed to prepare various metal/metal-oxide nanocatalysts. Until now, millimeter-scale, bead-shaped, cobalt egg-shell catalysts have been used to enhance the rate of reactant diffusion and catalyst performance. In the present work, new SiO2@Co/mSiO2 egg-shell nanoreactors (~300 nm) were synthesized with controlled Co content of 10 and 20 wt%. This was accomplished using a selective melt-infiltration process with porous silica shells around solid-silica cores. The SiO2@Co(10 wt%)/mSiO2 egg-shell catalyst that bears small cobalt nanoparticles of -2 nm was successfully employed for the industrially valuable Fischer-Tropsch synthesis reaction, showing the high activity of -8.0 x 10(-5) mol(CO) x gCo(-1) x S(-1).

Nanocrystalline Iron-Ore-Based Catalysts for Fischer-Tropsch Synthesis.

Nanocrystalline iron ore particles were fabricated by a wet-milling process using an Ultra Apex Mill, after which they were used as raw materials of iron-based catalysts for low-temperature Fischer-Tropsch synthesis (FTS) below 280 degrees C, which usually requires catalysts with a high surface area, a large pore volume, and a small crystallite size. The wet-milling process using the Ultra Apex Mill effectively destroyed the initial crystallite structure of the natural iron ores of several tens to hundreds of nanometers in size, resulting in the generation of nanocrystalline iron ore particles with a high surface area and a large pore volume. The iron-ore-based catalysts prepared from the nanocrystalline iron ore particles effectively catalyzed the low-temperature FTS, displaying a high CO conversion (about 90%) and good C5+ hydrocarbon productivity (about 0.22 g/g(cat)(-h)). This demonstrates the feasibility of using the iron-ore-based catalysts as inexpensive and disposable catalysts for the low-temperature FTS.

A new synthesis of carbon encapsulated Fe5C2 nanoparticles for high-temperature Fischer-Tropsch synthesis.

Using a simple thermal treatment under a CO flow, uniform micrometer-sized iron oxalate dihydrate cubes prepared by hydrothermal reaction were transformed into Fe5C2@C nanoparticles to form a mesoporous framework; the final structure was successfully applied to the high-temperature Fischer-Tropsch reaction and it showed high activity (CO conversion = 96%, FTY = 1.5 × 10(-4) molCO gFe(-1) s(-1)) and stability.

Ingestion of Portland Cement.

BACKGROUND: The common toxicities of cement are allergic dermatitis, abrasions, and chemical burns, but reports of cement ingestion are rare. In this study, we report a case of successful treatment of cement ingestion using emergency gastrointestinal endoscopy. CASE REPORT: An 83-year-old female was admitted to the emergency department with altered mental state and abdominal pain. We assumed that she ingested cement based on her medical history and radiologic examination. A previous report recommended surgical removal with gastric lavage. However, we thought that wet cement is highly alkaline, and gastric lavage is contraindicated. We performed emergency gastrointestinal endoscopy, instead of gastric lavage. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: If a patient ingests cement, the recommendation is to check the status of the upper gastrointestinal tract and remove the cement by emergency gastrointestinal endoscopy as soon as possible.

OsCpn60α1, encoding the plastid chaperonin 60α subunit, is essential for folding of rbcL.

Chaperonins are involved in protein-folding. The rice genome encodes six plastid chaperonin subunits (Cpn60) - three α and three ß. Our study showed that they were differentially expressed during normal plant development. Moreover, five were induced by heat stress (42°C) but not by cold (10°C). The oscpn60α1 mutant had a pale-green phenotype at the seedling stage and development ceased after the fourth leaf appeared. Transiently expressed OsCpn60α1:GFP fusion protein was localized to the chloroplast stroma. Immuno-blot analysis indicated that the level of Rubisco large subunit (rbcL) was severely reduced in the mutant while levels were unchanged for some imported proteins, e.g., stromal heat shock protein 70 (Hsp70) and chlorophyll a/b binding protein 1 (Lhcb1). This demonstrated that OsCpn60α1 is required for the folding of rbcL and that failure of that process is seedling-lethal.

Mutation in Wilted Dwarf and Lethal 1 (WDL1) causes abnormal cuticle formation and rapid water loss in rice.

Epidermal cell layers play important roles in plant defenses against various environmental stresses. Here we report the identification of a cuticle membrane mutant, wilted dwarf and lethal 1 (wdl1), from a rice T-DNA insertional population. The mutant is dwarf and die at seedling stage due to increased rates of water loss. Stomatal cells and pavement cells are smaller in the mutant, suggesting that WDL1 affects epidermal cell differentiation. T-DNA was inserted into a gene that encodes a protein belonging to the SGNH subfamily, within the GDSL lipase superfamily. The WDL1-sGFP signal coincided with the RFP signal driven by AtBIP-mRFP, indicating that WDL1 is an ER protein. SEM analyses showed that their leaves have a disorganized crystal wax layer. Cross-sectioning reveals loose packing of the cuticle and irregular thickness of cell wall. Detailed analyses of the epicuticular wax showed no significant changes either in the total amount and amounts of each monomer or in the levels of lipid polymers, including cutin and other covalently bound lipids, attached to the cell wall. We propose that WDL1 is involved in cutin organization, affecting depolymerizable components.

Inactivation of the CTD phosphatase-like gene OsCPL1 enhances the development of the abscission layer and seed shattering in rice.

Although susceptibility to seed shattering causes severe yield loss during cereal crop harvest, it is an adaptive trait for seed dispersal in wild plants. We previously identified a recessive shattering locus, sh-h, from the rice shattering mutant line Hsh that carries an enhanced abscission layer. Here, we further mapped sh-h to a 34-kb region on chromosome 7 by analyzing 240 F(2) plants and five F(3) lines from the cross between Hsh and Blue&Gundil. Hsh had a point mutation at the 3' splice site of the seventh intron within LOC_Os07g10690, causing a 15-bp deletion of its mRNA as a result of altered splicing. Two transferred DNA (T-DNA) insertion mutants and one point mutant exhibited the enhanced shattering phenotype, confirming that LOC_Os07g10690 is indeed the sh-h gene. RNA interference (RNAi) transgenic lines with suppressed expression of this gene exhibited greater shattering. This gene, which encodes a protein containing a conserved carboxy-terminal domain (CTD) phosphatase domain, was named Oryza sativa CTD phosphatase-like 1 (OsCPL1). Subcellular localization and biochemical analysis revealed that the OsCPL1 protein is a nuclear phosphatase, a common characteristic of metazoan CTD phosphatases involved in cell differentiation. These results demonstrate that OsCPL1 represses differentiation of the abscission layer during panicle development.

Rice OGR1 encodes a pentatricopeptide repeat-DYW protein and is essential for RNA editing in mitochondria.

RNA editing is the alteration of RNA sequences via insertion, deletion and conversion of nucleotides. In flowering plants, specific cytidine residues of RNA transcribed from organellar genomes are converted into uridines. Approximately 35 editing sites are present in the chloroplasts of higher plants; six pentatricopeptide repeat genes involved in RNA editing have been identified in Arabidopsis. However, although approximately 500 editing sites are found in mitochondrial RNAs of flowering plants, only one gene in Arabidopsis has been reported to be involved in such editing. Here, we identified rice mutants that are defective in seven specific RNA editing sites on five mitochondrial transcripts. Their various phenotypes include delayed seed germination, retarded growth, dwarfism and sterility. Mutant seeds from heterozygous plants are opaque. This mutation, named opaque and growth retardation 1 (ogr1), was generated by T-DNA insertion into a gene that encodes a pentatricopeptide repeat protein containing the DYW motif. The OGR1-sGFP fusion protein is localized to mitochondria. Ectopic expression of OGR1 in the mutant complements the altered phenotypes. We conclude that OGR1 is essential for RNA editing in rice mitochondria and is required for normal growth and development.

Constitutively wilted 1, a member of the rice YUCCA gene family, is required for maintaining water homeostasis and an appropriate root to shoot ratio.

Increasing its root to shoot ratio is a plant strategy for restoring water homeostasis in response to the long-term imposition of mild water stress. In addition to its important role in diverse fundamental processes, indole-3-acetic acid (IAA) is involved in root growth and development. Recent extensive characterizations of the YUCCA gene family in Arabidopsis and rice have elucidated that member's function in a tryptophan-dependent IAA biosynthetic pathway. Through forward- and reverse-genetics screening, we have isolated Tos17 and T-DNA insertional rice mutants in a CONSTITUTIVELY WILTED1 (COW1) gene, which encodes a new member of the YUCCA protein family. Homozygous plants with either a Tos17 or T-DNA-inserted allele of OsCOW1 exhibit phenotypes of rolled leaves, reduced leaf widths, and lower root to shoot ratios. These phenotypes are evident in seedlings as early as 7-10 d after germination, and remain until maturity. When oscow1 seedlings are grown under low-intensity light and high relative humidity, the rolled-leaf phenotype is greatly alleviated. For comparison, in such conditions, the transpiration rate for WT leaves decreases approx. 5- to 10-fold, implying that this mutant trait results from wilting rather than being a morphogenic defect. Furthermore, a lower turgor potential and transpiration rate in their mature leaves indicates that oscow1 plants are water-deficient, due to insufficient water uptake that possibly stems from that diminished root to shoot ratio. Thus, our observations suggest that OsCOW1-mediated IAA biosynthesis plays an important role in maintaining root to shoot ratios and, in turn, affects water homeostasis in rice.