Isroaniso matrix precursor synthesized from commercially available petroleum pitch was stabilized in air. The influence of oxygen mass gain during stabilization on the yield of matrix precursor was studied. Additionally, the influence of pressure on the yield of the stabilized matrix precursor in a real system was studied. The fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TGA), yield, yield rate, and yield impact were used to check the effect of stabilization and pressure on the yield of the matrix precursor and the end properties of the composite thereafter. The results showed that the yield increased with stabilization duration up to 20 h whereas it decreased for stabilization duration beyond 20 h. Further results showed that the stabilized matrix precursor for a duration of 5 h could withstand almost two-fold greater hot-pressing pressure without resulting in exudation as compared to that of a 1 h stabilized matrix precursor. The enhanced hot-pressing pressure significantly improved the yield of the matrix precursor. As a consequence, the densification and mechanical properties were increased significantly. Further, the matrix precursor stabilized for a duration of 20 h or more failed to provide proper and uniform binding of the reinforcement.

Nitrogen-atom doped graphene oxide was considered to prevent the dissolution of polysulfide and to guarantee the enhanced redox reaction of sulfur for good cycle performance of lithium sulfur cells. In this study, we used urea as a nitrogen source due to its low cost and easy preparation. To find the optimum urea content, we tested three different ratios of urea to graphene oxide. The morphology of the composites was examined by field emission scanning electron microscope. Functional groups and bonding characterization were measured by X-ray photoelectron spectroscopy. Electrochemical properties were characterized by cyclic voltammetry in an organic electrolyte solution. Compared with thermally reduced graphene/sulfur (S) composite, nitrogen-doped graphene/S composites showed higher electroactivity and more stable capacity retention.

Ni1/3Co1/3Mn1/3(OH)2 powders have been synthesized in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH using NH4OH as a chelating agent. The co-precipitation temperature is varied in the range of 30-80oC. Calcination of the prepared precursors with Li2CO3 for 8 h at 1000oC in air results in Li Ni1/3Co1/3Mn1/3O2 powders. Two kinds of obtained powders have been characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analyzer, and tap density measurements. The co-precipitation temperature does not differentiate the XRD patterns of precursors as well as their final powders. Precursor powders are spherical and dense, consisting of numerous acicular or flaky primary particles. The precursors obtained at 70 and 80oC possess bigger primary particles having more irregular shapes than those at lower temperatures. This is related to the lower tap density measured for the former. The final powders show a similar tendency in terms of primary particle shape and tap density. Electrochemical characterization shows that the initial charge/discharge capacities and cycle life of final powders from the precursors obtained at 70 and 80oC are inferior to those at 50oC. It is concluded that the optimum co-precipitation temperature is around 50oC.

Skin-derived precursors (SKPs) have potential to differentiate to various cell types including osteoblasts, adipocytes and neurons. SKPs are a candidate for cell-based therapy since they are easily accessible and have multipotency. Most mammalian cells are exposed to a low oxygen environment with 1 to 5% O2 concentration in vivo, while 21% O2 concentration is common in in vitro culture. The difference between in vitro and in vivo O2 concentration may affect to the behavior of cultured cells. In this report, we investigated the effect of hypoxic condition on stemness and proliferation of SKPs. The results indicated that SKPs exposed to hypoxic condition for 5 days showed no change in proliferation. In terms of mRNA expression, hypoxia maintained expression of stemness markers; whereas, oncogenes, such as Klf4 and c-Myc, were downregulated, and the expression of Nestin, related to cancer migration, was also downregulated. Thus, SKPs cultured in hypoxia may reduce the risk of cancer in SKP cell-based therapy.

When a single inorganic precursor is used for the synthesis of a sol-gel coating, there is a problem of cracking on the surface of coating layer. In order to solve this problem of surface cracking, we synthesized inorganic-organic coatings that have hybrid properties of inorganic and organic materials. Sols of various ratios (1:0.07, 0.2, 0.41, 0.82, 1.64, 3.26, 6.54, 13.2) of an inorganic precursor of Tetrabutylorthotitanate (Ti(OBu)4, TBOT) and an organic precursor of γ-Methacryloxy propyltrimethoxysilane (MAPTS) were prepared and coated on stainless steels (SUS316L) by dip coating method. The binding structure and the physical properties of the synthesized coatings were analyzed by FT-IR, FE-SEM, FIB (Focused Ion Beam), and a nano-indenter. Dynamic polarization testing and EIS (electrical impedance spectroscopy) were carried out to evaluate the micro-defects and the corrosion properties of the coatings. The prepared coatings show hybrid properties of inorganic oxides and organic materials. Crack free coatings were prepared when the MAPTS ratio was above a critical value. As the MAPTS ratio increased, the thickness and the corrosion resistance increased, and the hardness decreased.

High-quality colloidal CdSe/ZnS (core/shell) is synthesized using a continuous microreactor. The particle size of the synthesized quantum dots (QDs) is a function of the precursor flow rate; as the precursor flow rate increases, the size of the QDs decreases and the band gap energy increases. The photoluminescence properties are found to depend strongly on the flow rate of the CdSe precursor owing to the change in the core size. In addition, a gradual shift in the maximum luminescent wave (λmax) to shorter wavelengths (blue shift) is found owing to the decrease in the QD size in accordance with the quantum confinement effect. The ZnS shell decreases the surface defect concentration of CdSe. It also lowers the thermal energy dissipation by increasing the concentration of recombination. Thus, a relatively high emission and quantum yield occur because of an increase in the optical energy emitted at equal concentration. In addition, the maximum quantum yield is derived for process conditions of 0.35 ml/min and is related to the optimum thickness of the shell material.

We report a synthesis of non-toxic InP nanocrystals using non-pyrolytic precursors instead of pyrolytic and unstable tris(trimethylsilyl)phosphine, a popular precursor for synthesis of InP nanocrystals. In this study, InP nanocrystals are successfully synthesized using hexaethyl phosphorous triamide (HPT) and the synthesized InP nanocrystals showed a broad and weak photoluminescence (PL) spectrum. As synthesized InP nanocrystals are subjected to further surface modification process to enhance their stability and photoluminescence. Surface modification of InP nanocrystals is done at 230°C using 1-dodecanethiol, zinc acetate and fatty acid as sources of ZnS shell. After surface modification, the synthesized InP/ZnS nanocrystals show intense PL spectra centered at the emission wavelength 612 nm through 633 nm. The synthesized InP/ZnS core/shell structure is confirmed with X-ray diffraction (XRD) and Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES). After surface modification, InP/ZnS nanocrystals having narrow particle size distribution are observed by Field Emission Transmission Electron Microscope (FE-TEM). In contrast to uncapped InP nanocrystals, InP/ZnS nanocrystals treated with a newly developed surface modified procedure show highly enhanced PL spectra with quantum yield of 47%.

The effect of precursor concentration on the structural, morphological, and optical properties of TiO2nano-flowers was investigated in this study. An increase in crystallite size was observed with an increase in the concentration of the precursor (titanium butoxide). The FE-SEM micrographs of the as-prepared samples show a three-dimensional flower-like morphology. The flowers consist of several nanorods coming out of a single core and have very sharp edges. Also, the variation in the aspect ratio of the nanostructure was observed with the concentration of the precursor. The photocatalytic properties of the samples show that the sample that has a high aspect ratio (AR~9) has a much better photocatalytic activity compared to the nano-crystal with a low aspect ratio (AR~6.1). It is believed that the excellent photocatalytic performance and short time synthesis of TiO2nano-flowers using the microwave hydrothermal method can have potential applications in the field of photocatalysis.

본 연구는 유화형 소시지와 유사한 향미성분을 갖는 저지방 소시지를 개발하기 위해 지방에서 유래하는 향미성분의 전구체인 아미노산과 당을 첨가하여 기존의 유화형 소시지와 유사한 향미를 갖는 저지방 소시지의 개발을 위해 실시하였다. 저지방 소시지에서 지방감소로 인한 향미성분의 변화는 당과 아미노산을 첨가함으로써 대부분의 향미성분이 유화형 소시지와 비슷한 농도를 보였으며, 그중 저지방 소시지에 포도당(glucose) 과 아미노산인 라이신(lysine)을 각각 0.1 M 첨가 시 유화형 소시지와 가장 유사한 성상의 향미성분을 나타내었다. 이에 저지방 소시지에 지방 전구체로서 glucose와 lysine의 첨가는 지방 저감에 따른 향미 특성 변화를 보완 할 수 있을 것으로 사료된다.

Process conditions for the impregnation of polycarbosilane preceramic polymer into SiC-based composites were investigated. Two kinds of preceramic polymer (PCP) was impregnated into SiC-fiber fabrics with different solvents of n-hexane and divinylbenzene (DVB). Both microstructural observations and mechanical tests were conducted to evaluate the impregnation. The matrix phases were particulated in the case of hexane solvents. Apparent relative density of the matrix was about 78.8%. The density of matrix was increased to about 96.1-98.8% when the DVB was used; however, brittle fracture was observed during a bending test. The modulus of toughness was less than 0.74J/m3. The fabric impregnated with a mixed PCP-dissolved solution showed intermediate characteristics with relative high density of filling (apparent density of ~96.1%) as well as proper bending behavior. The modulus of toughness was increased to about 5.31J/m3. The composites developed by changing the precursor and solvent suggested the possibility of fabricating SiCf/SiC composites without a fiber to matrix interphase coating.

Architecture is a product of numerous influences, as shown in the apprenticeships of Kim, Jung-Up and Kim, Swoo-Geun with Le Corbusier’s influences. Therefore, its identity is need to be re-defined based on such complex relationships. The rhetorical images of ‘the Map of Misreading’, as the core of the poetic identification proposed by Harold Bloom’s ‘the Theory of Influence’, provide an efficient way of explaining the relations between architectural apprenticeships and identities. This research is to re-build a new methodology of architectural criticism based on it. The diachronic transformations of the architecture of Seung, Hyo-Sang also had very characteristic ‘revisionary ratios’ about his precursor Kim, Swoo-Geun. As an antithetic stance of his precursor’s final phase, his early days works pursued continuously geometric abstraction and objective images of the architecture of Adolf Loos. However, his recent works are showing the obvious symptoms of regression to his origins. Finally, the architectural identity should be re-conceptualized as a complexity, based on inter-textuality from complex influences. This new architectural identity can be reflected into the modern obsessive identity.

In this study, we fabricated Nd2Fe14B hard magnetic powders with various sizes via spray drying combined with reduction-diffusion process. Spray drying is widely used to produce nearly spherical particles that are relatively homogeneous. Thus, the precursor particles were prepared by spray drying using the aqueous solution containing Nd salts, Fe salts and boric acid with the target stoichiometric composition of Nd2Fe14B. The mean particle sizes of the spray-dried powders are in the range from one to seven micrometer, which are adjusted by controlling the concentra- tions of precursor solutions. After debinding the as-prepared precursor particles, ball milling was also conducted to con- trol the particle sizes of Nd-Fe-B oxide powders. The resulting particles with different sizes were subjected to subsequent treatments including hydrogen reduction, Ca reduction and washing for CaO removal. The size effect of Nd-Fe-B oxide particles on the formation of Nd2Fe14B phase and magnetic properties was investigated.

Coal tar is the primary feedstock of premium graphitizable carbon precursor. Coal tars are residues formed as byproducts of thermal treatments of coal. Coal tar pitches were prepared through two different heat treatment schedules and their properties were characterized. One was prepared with argon and oxidation treatment with oxygen; the other was prepared with oxygen treatment at low temperature and then argon treatment at high temperature; both used coal tar to prepare coal tar pitches. To modulate the properties, different heat treatment temperatures (300~400˚C) were used for the coal tar pitches. The prepared coal tar pitches were investigated to determine several properties, such as softening point, C/H ratio, coke yield, and aromaticity index. The coal tar pitches were subject to considerable changes in chemical composition that arose due to polymerization after heat treatment. Coal tar pitch showed considerable increases in softening point, C/H ratio, coke yields, and aromaticity index compared to those characteristics for coal tar. The contents of gamma resin, which consists of low molecular weight compounds in the pitches and is insoluble in toluene, showed that the degree of polymerization in the pitches was proportional to C/H ratio. Using an oxidizing atmosphere like air to prepare the pitches from coal tar was an effective way to increase the aromaticity index at relatively low temperature.

Skin-derived precursor cells (SKPs) are multipotent, sphere-forming and embryonic neural crest‐related precu- rsor cells that can be isolated from dermis. It is known that the properties of porcine SKPs can be enhanced by leuke- mia inhibitory factor (LIF) which is an essential factor for the generation of embryonic stem cells in mice. In our pre- sent study, to enhance or maintain the properties of murine SKPs, LIF was added to the culture medium. SKPs were treated with 1,000 IU LIF for 72 hours after passage 3. Quantitative real time RT‐PCR was then performed to quantify the expression of the pluripotent stem cell specific genes Oct4, Nanog, Klf4 and c‐Myc, and the neural crest specific genes Snai2 and Ngfr. The results show that the expression of Oct4 is increased in murine SKPs by LIF treatment whereas the level of Ngfr is decreased under these conditions. Interestingly, LIF treatment reduced Nanog exp- ression which is also important for cell proliferation in adult stem cells and for osteogenic induction in mesenchymal stem cells. These findings implicate LIF in the maintenance of stem- ness in SKPs through the suppression of lineage differen- tiation and in part through the control of cell proliferation.

The quantum dots (QD) have unique electrical and optical properties due to quantum dot confinement effect. The optical properties of QDs are decided by various synthesis conditions. In a prior QDs study, a study on the QDs size with synthesis condition such as synthesis time and temperature is being extensively researched. However, the research on QDs size with composition ratio has hitherto received scant attention. In order to evaluate the ratio dependence of CdSe crystal, synthesis ratio of Se precursor is changed from 16.7 mol%Se to 44 mol%Se. As the increasing Se ratio, the band gap was increased. This is caused by red shift of emission. We confirmed optical property of CdSe QDs with composition ratio.

[ LaMeO3 ](Me = Cr, Co) powders were prepared using the polymeric precursor method. The effects of the chelating agent and the polymeric additive on the synthesis of the LaMeO3 perovskite were studied. The samples were synthesized using ethylene glycol (EG) as the solvent, acetyl acetone (AcAc) as the chelating agent, and polyvinylpyrrolidone (PVP) as the polymer additive. The thermal decomposition behavior of the precursor powder was characterized using a thermal analysis (TG-DTA). The crystallization and particle sizes of the LaMeO3 powders were investigated via powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and particle size analyzer, respectively. The as-prepared precursor primarily has LaMeO3 at the optimum condition, i.e. for a molar ratio of both metal-source (a : a) : EG (80a : 80a) : AcAc (8a) inclusive of 1 wt% PVP. When the as-prepared precursor was calcined at 700˚C, only a single phase was observed to correspond with the orthorhombic structure of LaCrO3 and the rhombohedral structure of LaCoO3. A solid-electrolyte impedance-metric sensor device composed of Li1.5Al0.5Ti1.5(PO4)3 as a transducer and LaMeO3 as a receptor has been systematically investigated for the detection of NOx in the range of 20 to 250 ppm at 400˚C. The sensor responses were able to divide the component between resistance and capacitance. The impedance-metric sensor for the NO showed higher sensitivity compared with NO2. The responses of the impedance-metric sensor device showed dependence on each value of the NOx concentration.

Due to their novel properties, GaN based semiconductors and their nanostructures are promising components in a wide range of nanoscale device applications. In this work, the gallium nitride is deposited on c-axis oriented sapphire and porous SWCNT substrates by molecular beam epitaxy using a novel single source precursor of Me2Ga(N3)NH2C(CH3)3 with ammonia as an additional source of nitrogen. The advantage of using a single molecular precursor is possible deposition at low substrate temperature with good crystal quality. The deposition is carried out in a substrate temperature range of 600-750˚C. The microstructural, structural, and optical properties of the samples were analyzed by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and photoluminescence. The results show that substrate oriented columnar-like morphology is obtained on the sapphire substrate while sword-like GaN nanorods are obtained on porous SWCNT substrates with rough facets. The crystallinity and surface morphology of the deposited GaN were influenced significantly by deposition temperature and the nature of the substrate used. The growth mechanism of GaN on sapphire as well as porous SWCNT substrates is discussed briefly.

Polysilazane and silazane-based precursor films were deposited on stacked TiN/Ti/TEOS/Si-substrate by spin-coating, then annealed at 150~400oC, integrated further to form the top electrode and pad, and finally characterized. Theprecursor solutions were composed of 20% perhydro-polysilazane (SiH2NH)n, and 20% hydropolymethyl silazane(SiHCH3NH)n in dibutyl ether. Annealing of the precursor films led to the compositional change of the two chemicals intosilicon (di)oxides, which was confirmed by Fourier transform infrared spectroscopy (FTIR) spectra. It is thought that thedifferent results that were obtained originated from the fact that the two precursors, despite having the same synthetic routeand annealing conditions, had different chemical properties. Electrical measurement indicated that under 0.6MV/cm, a largercapacitance of 2.776×10−11 F and a lower leakage current of 0.4pA were obtained from the polysilazane-based dielectric films,as compared to 9.457×10−12 F and 2.4pA from the silazane-based film, thus producing a higher dielectric constant of 5.48compared to 3.96. FTIR indicated that these superior electrical properties are directly correlated to the amount of Si-O bondsand the improved chemical bonding structures of the spin-on dielectric films, which were derived from a precursor without C.The chemical properties of the precursor films affected both the formation and the electrical properties of the spin-on dielectricfilm.

Cells that have endogenous multipotent properties can be used as a starting source for the generation of induced pluripotent cells (iPSC). In addition, small molecules associated with epigenetic reprogramming are also widely used to enhance the multi- or pluripotency of such cells. Skinderived precursor cells (SKPs) are multipotent, sphereforming and embryonic neural crest-related precursor cells. These cells can be isolated from a juvenile or adult mammalian dermis. SKPs are also an efficient starting cell source for reprogramming and the generation of iPSCs because of the high expression levels of Sox2 and Klf4 in these cells as well as their endogenous multipotency. In this study, valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, was tested in the generation of iPSCs as a potential enhancer of the reprogramming potential of SKPs. SKPs were isolated from the back skins of 5-6 week old C57BL/6 X DBA/2 F1 mice. After passage 3, the SKPs was treated with 2 mM of VPA and the quantitative real time RT-PCR was performed to quantify the expression of Oct4 and Klf4 (pluripotency specific genes), and Snai2 and Ngfr (neural crest specific genes). The results show that Oct4 and Klf4 expression was decreased by VPA treatment. However, there were no significant changes in neural crest specific gene expression following VPA treatment. Hence, although VPA is one of the most potent of the HDAC inhibitors, it does not enhance the reprogramming of multipotent skin precursor cells in mice.

Facial numbness restricted to the distribution of the mental nerve(mental neuropathy) is called "numb chin syndrome". The clinical importance of this syndrome is associated with first recognition of involvement of malignant diseases. The malignant neoplasm with numb chin syndrome show rapid progression and high mortality. We present a 43-year-old female who had been treated by radiotherapy for precursor T-cell leukemia/lymphoma involving the central nervous system( CNS) previously and later developed mental nerve invasion without central nervous system recurrence. MRI images revealed the CNS tumor mass remitted, and there was no identified peripheral nervous system(PNS) involvement including the mental nerve invasion, nevertheless the patient complained of consistent numbness and pain on right mandibular area. This is the first case of precursor T-cell leukemia/lymphoma accompanying mental nerve invasion without recurrence for central nervous system. Proper interpretation for mental neuropathy may lead to the prompt diagnosis and therapeutic intervention.