In the present work, Al- composite powders were fabricated using a mechanical milling process and its milling behaviors and mechanical properties as functions of sizes ( , 500 nm and 50 nm) and concentrations (1, 3 and 10 wt.%) were investigated. For achieving it, composite powders and their compacts were fabricated using a planetary ball mill machine and magnetic pulse compaction technology. Al- composite powders represent the most uniform dispersion at a milling speed of 200 rpm and a milling time of 240 minutes. Also, the smaller particles were presented, the more excellent compositing characteristics are exhibited. In particular, in the case of the 50 nm added compact, it showed the highest values of compaction density and hardness compared with the conditions of and 500 nm additions, leading to the enhancement its mechanical properties.

A recent study has reported that pluripotent stem cells can be categorized according to their pluripotent state. The first is a “naïve” state, which is characterized by small, round or dome-shaped colony morphologies, LIF and BMP4 signaling pathways and two active X chromosomes in female; mouse ES cells (mESCs) represent this type. A second “primed” state has also been described and is possible in mouse epiblast stem cells (mEpiSCs) or human ES cells (hESCs). These primed state pluripotent stem cells display flattened monolayer colony morphologies, FGF and Nodal/Activin signaling pathways and X chromosome inactivation in female. It has been suggested that, as a non-permissive species, the porcine species undergoes reprogramming into a primed state during the establishment of pluripotent stem cell lines. Meanwhile, a few studies have reported that primed pluripotent stem cell lines could be reverted to a naïve pluripotent state using various exogenous factors including GSK3β and MEK inhibitors, LIF, hypoxic conditions and up-regulation of Oct3 or klf4. Therefore, the purpose of this study was to investigate whether a LIF-dependent naïve pluripotent stem cell line could be derived from porcine embryonic fibroblasts(PEFs) via doxycycline (dox)-inducible reprogramming factors and LIF. In this study, we have been able to successfully induce PEFs into a LIF-dependent naïve pluripotent-like cell line showing a mESC-like morphology and the expression of pluripotent markers. Our results suggest the possibility of reprogramming to naive pluripotent- like stem cells from PEFs in porcine species. * This work was supported by the BioGreen 21 Program (PJ0081382011), Rural Development Administration, Republic of Korea.

This study investigated refinement behaviors of TiC powders produced under different impact energy conditions using a mechanical milling process. The initial coarse TiC powders with an average diameter of 9.3 were milled for 5, 20, 60 and 120 mins through the conventional low energy mechanical milling (LEMM, 22G) and specially designed high energy mechanical milling (HEMM, 65G). TiC powders with angular shape became spherical one and their sizes decreased as the milling time increased, irrespective of milling energy. Based upon the FE-SEM and BET results of milled powders, it was found initial coarse TiC powders readily became much finer near 100 nm within 60 min under HEMM, while their sizes were over 200 nm under LEMM, despite the long milling time of up to 120 min. Particularly, ultra-fine TiC powders with an average diameter of 77 nm were fabricated within 60 min in the presence of toluene under HEMM.

In this study, p-type : TAGS-85 compound powders were prepared by gas atomization process, and then their microstructures and mechanical properties were investigated. The fabricated powders were of spherical shape, had clean surface, and illustrated fine microstructure and homogeneous + GeTe solid solution. Powder X-ray diffraction results revealed that the crystal structure of the TAGS-85 sample was single rhombohedral GeTe phase, which with a space group . The grain size of the powder particles increased while the micro Vickers hardness decreased with increasing annealing temperature within the range of 573 K and 723 K due to grain growth and loss of Te. In addition, the crystal structure of the powder went through a phase transformation from rhombohedral () at low-temperature to cubic () at high-temperature with increasing annealing temperature. The micro Vickers hardness of the as-atomized powder was around 165 Hv, while it decreased gradually to 130 Hv after annealing at 673K, which is still higher than most other fabrication processes.

Several studies have been conducted with the aim of establishing embryonic stem cell lines from porcine embryos. However, most researchers to date have found it difficult to maintain an ES-like state in derived cell lines, with the cells showing a strong tendency to differentiate into an epithelial or EpiSC-like state. We have also been able to derive cell lines of an EpiSC-like state and a differentiated non-ES-like state from porcine embryos of various origins, including invitro fertilized(IVF), in vivo derived, IVF aggregated and parthenogenetic embryos. In addition, we have generated induced pluripotent stem cells(piPSCs) via plasmid transfection of reprogramming factors (Oct4, Sox2, Klf4 and c-Myc) into porcine fibroblast cells. X chromosome inactivation (XCI) have recently been addressed as a hallmark to determine whether pluripotent cell is naïve or primed state. In this study, we could confirm the X chromosome inactivation status in female cell lines as well as marker expression, pluripotency and of our Epi- SC-like pESC lines along with our piPSC line. All of our cell lines showed AP activity and expressions of the genes Oct4, Sox2, Nanog, Rex, TDGF1, bFGF, FGFR1, FGFR2, Nodal and Activin-A involved in pluripotency and signaling pathways, XCI in female cell lines, in vitro differentiation potential and a normal karyotype, thus displaying similarities to epiblast stem cells or hES cells. Therefore, it may be inferred that, as a non-permissive species, the porcine species undergoes reprogramming into a primed state during the establishment of pluripotent stem cell lines.

The Ni-based bulk metallic glass matrix composites were fabricated by spark plasma sintering of mixture of gas-atomized metallic glass powders and ductile brass powders. The successful consolidation of metallic glass matrix composite was achieved by strong bonding between metallic glass powders due to viscous flow deformation and lower stress of ductile brass powders in the supercooled liquid state during spark plasma sintering. The composite shows some macroscopic plasticity after yielding, which was obtained by introducing a ductile second brass phase in the Ni-based metallic glass matrix.

Using Spark Plasma Sintering process (SPS), consolidation behavior of gas atomized alloys were investigated via examining the microstructure and evaluating the mechanical properties. In the atomized ahoy powders, fine particles were homogeneously distributed in the matrix. The phase distribution was maintained even after SPS at 723 K, although particles were newly precipitated by consolidating at 748 K. The density of the consolidated bulk Mg-Zn-Y alloy was . The ultimate tensile strength (UTS) and elongation were varied with the consolidation temperature.

This work is to present a new synthesis of metallic glass (MG)/metallic glass (MG) composites using gas atomization and spark plasma sintering (SPS) processes. The MG powders of (CuA) and (NiA) as atomized consist of fully amorphous phases and present a different thermal behavior; (glass transition temperature) and (crystallization temperature) are 716K and 765K for the Cu base powder, but 836K and 890K for the Ni base ones, respectively. SPS process was used to consolidate the mixture of each amorphous powder, being in weight. The resultant phases were Cu crystalline dispersed NiA matrix composites as well as NiA phase dispersed CuA matrix composites, depending on the SPS temperatures. Effect of the second phases embedded in the MG matrix was discussed on the micro-structure and mechanical properties.

Mathematical models have been developed to evaluate methane emission from landfills. The Intergovernmental Panel on Climate Change (IPCC) and the US Environmental Protection Agency (USEPA) have provided first-order decay (FOD) models to estimate methane emission from landfills. The methane generation potential (L0) and the methane generation rate constant (k) are the two primary parameters in the FOD model. A major challenge in landfill gas modeling is estimating these parameters. The IPCC recommended that every country should develop country-specific emission factors appropriate for its circumstances and characteristics. The k value represents the rate constant associated with waste decomposition. In general, there are two different approaches for estimating a k value for a landfill. One uses actual field data in comparison with modeled data. However, this approach is limited by the spatial and temporal characteristics of landfill. Another approach is to collect samples of landfilled waste and then measure their biodegradability of waste as a function of waste age. As biodegradability is a surrogate for landfilling age, lower biodegradability would be expected in order samples. The objective of this study was to determine a k value using an anaerobic test (GB21). To achieve this objective, the GB21 which is used in Germany was conducted to estimate biodegradability of waste samples, and k value was determined based on FOD equation. Waste samples were collected at a landfill located in A City, Korea. The landfill is a valley-type landfill. It received municipal solid waste from 1990 to 2010. Food and paper wastes were the major fractions, constituting about 62.9% of the total amount disposed. However, the Ministry of Environment in Korea banned direct landfilling of food wastes in 2005, since then, food waste has no longer been disposed into landfills. In this study, the landfill site was separated into four areas based on landfilling age, and four samples were collected from each area. Cumulative biogas production for the waste excavated from the landfill varied from 6.9 to 35.8 Nl/kg-Dry Matter. Cumulative biogas production for landfilling age of 1 year was 35.8 Nl/kg-DM and it decreased to 6.9 Nl/kg-DM after 14 years. The k value obtained from this study was 0.156 yr-1 and was higher than the default k prescribed by the IPCC, which is 0.09 yr-1 in boreal and temperate climates. The higher k values obtained in this study can be explained by the high proportion of food waste disposed into the studied landfill. The default k values of rapidly degrading wastes including food waste and sludge are 0.185 yr-1. In addition a higher k value will result in predictions of more methane generation in the early years after waste burial, resulting in higher estimates of uncollected methane in greenhouse gas inventories. This work contributes to understanding decomposition rate of landfilled waste by examining biodegradability determination and providing k value for landfill.

Pluripotent stem cells are cells that have a self-renewal capacity and the ability to differentiate into all lineages. These cells can be divided into naive- and primed-state pluripotent stem cells according to their pluripotent state. Only the naive state comprises a full pluripotency or ground state that contributes to germ-line transmission. Naive states are found in specific permissive strains or species, such as 129, C57BL/6 and BALB/C in mice. However, a number of attempts have been made to derive naive-state pluripotent stem cell lines from non-permissive species, including humans and pigs, using various exogenous factors including GSK3β and MEK inhibitors (2i), LIF, hypoxic conditions and up-regulation of Oct4 or Klf4. Therefore, in this study we investigated whether a naive pluripotent stem cell line could be derived from porcine embryonic fibroblasts (PEFs) via previously reported factors. Our mouse embryonic stem cell (mESC)-like cell lines expressed the pluripotency markers Oct4, Sox2 and Nanog and a stable mESC-like morphology for more than 50 passages. In addition, these cell lines could be sequentially reprogrammed into mESC-like induced pluripotent stem (iPS) cells from secondary or tertiary fibroblast-like cells differentiated from mESC-like iPS cells by addition of doxycycline (DOX), LIF and 2i. Our results suggest that, as a non-permissive species, porcine stem cells can be induced into mESC-like iPS cells from PEFs by various exogenous factors, including continuous transgene expression, 2i and LIF. However, further work that aims to effectively induce the activation of endogenous transcription factors is necessary to derive authentic naive-state pluripotent porcine stem cells.