Molecular Dynamics Observation of Iron-Carbon Precursors of Carbon Nanotube and Development of Iron-Carbon Potential

We have focused on the growth process of metal and carbon mixed clusters that are precursors for carbon nanotubes. The molecular dynamics method using the Brenner potential was employed for modeling carbon-carbon interactions as well as carbon-iron interactions. As for carbon-iron interactions, the parameters were derived using DFT calculation. The Finnis-Sinclair potential was employed for irons. In order to observe the deposition process of carbon atoms, we adjusted the potential parameters to reproduce the bulk melting points of graphite, iron, and cementite, which was a model material of iron-carbon composite. We observed the initial growth process by preparing iron-carbon mixed clusters (approximately 200 iron atoms and 70 carbon atoms) as precursor clusters. Additional carbon atoms were then gradually supplied to this mixture at 1000 K and 1200 K. Consequently, the graphite structure was formed on the mixture surface, but at some phases, the cap structure was observed at 1200 K

Influence of the Catalyst Supporters upon the Catalyst Nano Particle for Synthesizing Single-walled Carbon Nanotubes

Controlling diameter and chirality of single-walled carbon nanotubes are most interesting aspects on synthesis, and these kinds of controls are desired to be done during the synthetic processes. In fact combination of catalysts, modifying their species, and adjusting the size of catalyst can roughly control the diameter distribution. However, since catalysts including cobalt atoms work much better for synthesizing SWNTs in alcohol catalytic chemical vapor deposition process, which is considered one of the best processes to synthesize, this fact restricts the flexibility of catalyst combination. Usually, supporters are used for avoiding the condensation of catalysts, but it turns out that sometimes these supporters give bad effects on catalysts of losing their catalytic activities. In this paper we synthesized SWNTs by using catalysts on different supporters and considered the influence of supporters by calculating their electronic structures

Identification of a Cytokine-induced Antiapoptotic Molecule Anamorsin Essential for Definitive Hematopoiesis

Many growth factors and cytokines prevent apoptosis. Using an expression cloning method, we identified a novel antiapoptotic molecule named Anamorsin, which does not show any homology to known apoptosis regulatory molecules such as Bcl-2 family, caspase family, or signal transduction molecules. The expression of Anamorsin was completely dependent on stimulation with growth factors such as interleukin 3, stem cell factor, and thrombopoietin in factor-dependent hematopoietic cell lines, and forced expression of Anamorsin conferred resistance to apoptosis caused by growth factor deprivation in vitro. Furthermore, Anamorsin was found to act as an antiapoptotic molecule in vivo because Anamorsin−/− mice die in late gestation due to defective definitive hematopoiesis in the fetal liver (FL). Although the number of hematopoietic stem/progenitor cells in the FL did not decrease in these mice, myeloid, and particularly erythroid colony formation in response to cytokines, was severely disrupted. Also, Anamorsin−/− erythroid cells initiated apoptosis during terminal maturation. As for the mechanism of Anamorsin-mediated cell survival, a microarray analysis revealed that the expression of Bcl-xL and Jak2 was severely impaired in the FL of Anamorsin−/− mice. Thus, Anamorsin is considered to be a necessary molecule for hematopoiesis that mediates antiapoptotic effects of various cytokines

Catalytic supercritical water gasification of oil palm frond biomass using nanosized MgO doped Zn catalysts

In this work, nanosized MgO doped Zn catalysts (Mg1-x Znx O; x = 0.05, 0.10, 0.15, 0.20) were catalyzed the supercritical water gasification (SCWG) of oil palm frond (OPF) biomass for hydrogen production. Increased the amount of Zn in the catalyst enlarged the crystallite size, thus, reduced the surface area. Interestingly, all the synthesized catalysts have crystallite sizes of less than 50 nm. In-depth Rietveld refinement analysis revealed that the enlargement of the crystallite size is due to the phenomenon of cell expansion when the smaller Mg2+ ions being replaced by the larger Zn2+ ions during the doping process. Increased the Zn content also improved the basicity properties. Among the synthesized catalysts, the Mg0.80 Zn0.20 O exhibited the highest total gas volume of 213.5 ml g-1 of the biomass with 438.1% of increment in terms of H2 yield. The metal oxide doped materials serve as a new catalyst structure system for the SCWG technology

Complete genome sequence of Nitratireductor sp. strain OM-1:A lipid-producing bacterium with potential use in wastewater treatment

Reducing CO 2 emissions is necessary to alleviate rising global temperature. Renewable sources of energy are becoming an increasingly important substitute for fossil fuels. An important step in this direction is the isolation of novel, technologically relevant microorganisms. Nitratireductor sp. strain OM-1 can convert volatile short-chain fatty acids in wastewater into 2-butenoic acid and its ester and can accumulate intracellularly esterified compounds up to 50% of its dried cell weight under nitrogen- depleted conditions. It is believed that a novel fatty acid biosynthesis pathway including an esterifying enzyme is encoded in its genome. In this study, we report the whole-genome sequence (4.8 Mb) of OM-1, which comprises a chromosome (3,977,827 bp) and a megaplasmid (857,937 bp). This sequence information provides insight into the genome organization and biochemical pathways of OM-1. In addition, we identified lipid biosynthesis pathways in OM-1, paving the way to a better understanding of its biochemical characterization

Metal coating effect on thermal diffusivity of single-walled carbon nanotube

Recently a functionalized single-walled carbon nanotube (SWCNT) that is modified by metal atoms was experimentally developed. Single-walled carbon nanotube is known to exhibit exceptional thermal conductivity; however, there is no report about a functionalized SWCNT. In this study, thermal diffusivity of metal-coated SWCNT was derived using molecular dynamics. Consequently, thermal diffusivity exhibited 10 times smaller than uncoated SWCNT. On the other hand, the heat conduction on the metal layer was observed as the shape of shoulder on the thermal time response and it was found that this contribution was not small for a short-length SWCNT