The bumblebees, Bombus species are valuable natural resources being utilized for greenhouse pollination. Low level of genetic variation of Bombus species has been reported previously. In this study, we sequenced complete internal transcribed spacer 2 (ITS2) of the nuclear rDNA from 100 individuals of B. ardens collected from seven localities in Korean peninsula. The ITS2 sequence of B. ardens is longest, ranging in size from 1,940 bp-1,954 bp among known in insects, which ranges approximately from 241 bp-1,728 bp. The ITS2 sequences have ~51% of C+C content and contain each two 27 bp repeats, 20 bp repeats, 33 bp repeats, and 34 bp repeats at the beginning. Such repeats were not found in other insects. Uncorrected pairwise distance among 96 sequences that were obtained from 100 individuals revealed a maximum sequence divergence of 1.03%. Genetic diversity (π) of each population ranged from 0.007801 to 0.009627, and the lowest diversity was obtained from islet population of Ulleungdo, indicating possibly small, isolation of the population. Significant level of genetic distance was only found when Ulleungdo population was compared to two other mainland populations. Except for this, overall, a very high rate of per generation migration ratio (Nm=7.1-infinite) and a very low level of genetic fixation (FST=0-0.06546) were detected between pairs of localities. Analysis of hierarchical relationships among localities consistently revealed no statistically significant structure among populations. Taken these together, the B. ardens populations on the Korean peninsula are panmictic this is consistent with our understanding of the dispersal capability.

Cinnamate를 곁사슬로 포함하는 감광성 고분자를 poly(2-hydroxyethyl methacrylate) (PHEMA)로부터 합성하였다. Cinnamate 기가 25에서 97mol%까지 치환된 감광성 고분자를 PHEMA와 cinnamoyl chloride의 반응을 통해 합성하였으며, 반응 조건에 따른 치환율의 변화를 조사하였다. 합성된 고분자는 H-NMR과 FT-IR을 이용하여 구조 확인하였으며, DSC와 TGA를 이용한 열분석을 행하였다. 얻어진 고분자의 광 반응성은 UV/VIS spectrophotometer를 이용하여 확인하였고, 편광 자외선 조사를 이용한 액정의 광배향 특성에 대해서 연구하였다.

Silicon dioxide as gate dielectrics was grown at 400˚C on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of O2 and N2O to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature N2O annealing, nitrogen can be supplied to the Si/SiO2 interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/SiO2 interface by plasma oxidation as the N2O molecule is broken in the plasma and because a dense Si-N bond is formed at the SiO2 surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the Si/SiO2 interface by the plasma oxidation of mixtures of O2/N2O gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.

The HMG box containing protein (HBP) has a high mobility group domain and involved in the regulation of proliferation and differentiation of tissues. We screened HBP2 in glioblastoma using Suppression Subtractive Hybridization (SSH) and isolated human spermatogonial stem cell‐like cells (hSSC‐like cells) derived from patients of nonobstructive azoospermia (NOA). Expression of HBP2 was analyzed by RT‐PCR in undifferentiated stem cells (human Embryonic Stem Cells, hSSC‐like cells 2P) and spontaneous differentiated stem cells (hSSC‐like cells 4P). It was overexpressed in hESC and hSSC‐like cells 2P but not in hSSC‐like cells 4P. Also, the expression level of HBP2 was downregulated in colon tumor tissues compared to normal tissues. Specifically in synchronized WI‐38 cells, HBP2 was highly upregulated until the G1 phase of the cell cycle and gradually decreased during the S phase. Our results suggest that HBP2 was downregulated during the spontaneous differentiation of hSSC‐like cells. HBP2 was differently expressed in colon tissues and was related to G1‐progression in WI‐38 cells. It may play a role in the maintenance of an undifferentiated hSSC‐like cell state and transits from G1 to S in WI‐38 cells. This research was important that it identified a biomarker for an undifferentiated state of hSSC‐like cells and characterized its involvement to arrest during cell cycle in colon cancer.

ZnO nanopowders were synthesized by the sol-gel method using hydrazine reduction, and their gas responses to 6 gases (200 ppm of C2H5OH, CH3COCH3, H2, C3H8, 100 ppm of CO, and 5 ppm of NO2) were measured at 300 ~ 400˚C. The prepared ZnO nanopowders showed high gas responses to C2H5OH and CH3COCH3 at 400˚C. The sensing materials prepared at the compositions of [ZnCl2]:[N2H4]:[NaOH] = 1:1:1 and 1:2:2 showed particularly high gas responses (S = Ra/Rg, Ra : resistance in air, Rg : resistance in gas) to 200 ppm of C2H5OH(S = 102.8~160.7) and 200 ppm of CH3COCH3(S = 72.6~166.2), while they showed low gas responses to H2, C3H8, CO, and NO2. The reason for high sensitivity to these 2 gases was discussed in relation to the reaction mechanism, oxidation state, surface area, and particle morphology of the sensing materials.

Positive temperature coefficient of resistivity (PTCR) characteristics of (1-x)BaTiO3-x(Bi0.5K0.5)TiO3ceramics doped with Nb2O5 were investigated in order to develop the Pb-free PTC thermistor available at hightemperatures of >120oC. The PTCR characteristics appearing in the (Bi0.5Ki0.5)TiO3 (<5mol%) incorporatedBaTiO3 ceramics, which might be mainly due to Bi+3 ions substituting for Ba+2 sites. The 0.99BaTiO3-0.01(Bi0.5K0.5)TiO3 ceramics showed good PTCR characteristics of a low resistivity at room temperature (ρr) of31 Ω·cm, a high ρmax/ρmin ratio of 5.38×103, and a high resistivity temperature factor (α) of 17.8%/oC. Theaddition of Nb2O5 to 0.99BaTiO3-0.01(Bi0.5K0.5)TiO3 ceramics further improved the PTCR characteristics.Especially, 0.025mol% Nb2O5 doped 0.99BaTiO3-0.01(Bi0.5K0.5)TiO3 ceramics exhibited a significantly increasedρmax/ρmin ratio of 8.7×103 and a high α of 18.6%/oC, along with a high Tc of 148oC despite a slightly increasedρr of 39 Ω·cm.

Phospholipase A2 (PLA2) is the committed catalytic step of eicosanoid biosynthesis, which has been a common molecular target of several entomopathogens to induce insect immunosuppression. Despite critical importance of PLA2 in insect immunity, its gene structure was not known. This study identified insect PLA2 gene associated with immune reactions in the red flour beetle, Tribolium castaneum. Based on a previous study that an immune-associated PLA2 in insect is secretory type of PLA2 (sPLA2), five highly matched cDNA sequences were obtained from T. castaneum genome database using an sPLA2 sequence probe encoded in Drosophila melanogaster. The expressions of these five putative PLA2 were confirmed by reverse transcriptase-polymerase chain reaction. Out of five genes, one PLA2 gene called TcPLA2B was chosen because it showed specific expression in hemocyte and fat body. TcPLA2B was cloned and expressed in Escherichia coli and its protein was purified. The purified TcPLA2B showed PLA2enzyme activity, which was specifically inhibited by bromophenacyl bromide (a specific sPLA2inhibitor) and dithiothreitol (reducing agent of disulfide bond). It was sensitive to pH (optimum at pH 6.0) and reaction temperature (optimum at 10-30°C), and calcium dependency. An immunofluorescence assay indicated that TcPLA2B was localized near to cellular membrane of the cytosol in the hemocytes of T. castaneum at immune chanlenge. Double-stranded RNA (dsRNA) of TcPLA2B-treated larvae showed knockdown of its mRNA expression and did not form hemocyte nodule formation, while control larvae could exhibit time- and bacterial dose-dependent nodule formation in response to bacterial challenge. Addition of arachidonic acid (the catalytic product of PLA2) to the dsRNA-treated larvae rescued the inhibition of nodule formation. These results suggest that TcPLA2B gene is associated with insect immune reaction.

ZnS- composite is normally used for sputtering target. In recent years, high sputtering power for higher deposition rate often causes crack formation of the target. Therefore the target material is required that the sintered target material should have high crack resistance, excellent strength and a homogeneous microstructure with high sintered density. In this study, raw ZnS and ZnS- powders prepared by a 3-D mixer or high energy ball-milling were successfully densified by spark plasma sintering, the effective densification method of hard-to-sinter materials in a short time. After sintering, the fracture toughness was measured by the indentation fracture (IF) method. Due to the effect of crack deflection by the residual stress occurred by the second phase of fine , the hardness and fracture toughness reached to 3.031 GPa and , respectively

[ ] powders for lithium ion batteries were synthesized from two separate raw material pairs of LiOH/MnO and . The powders prepared at 780 and and their difference of electrochemical properties were investigated. Both powders calcined at 780 and were composed of a single-phase spinel structure but those treated at showed a lower intensity ratio of to , a slightly larger lattice parameter, and an increased discharge capacity by 10% under voltage range. The XPS study on the oxidation states of manganese repealed that powders made from LiOH/MnO had less ion and gave better battery performances than those from .

Warm compaction powder metallurgy was used to produce a Ti3SiC2 particulate reinforced Cu matrix composite. Fabrication parameters and warm compaction behaviors of Cu powder were studied. Based on the optimized fabrication parameters a Cu-based electrical contact material was prepared. Results showed that in expend of some electrical conductivity, addition of Ti3SiC2 particulate increased the hardness, wear resistivity and anti-friction ability of the sintered Cu-base material.

Nanostructured and composite powders have been prepared by mechanochemical reaction from mixtures of Ti, BN, and powders. The raw materials have reacted to form a uniform mixture of TiN, and or depending on the amount of used in the starting mixtures, and the reaction proceeded through so-called mechanically activated self-sustaining reaction (MSR). Fine TiN and crystallites less than a few tens of nanometer were homogeneously dispersed in the amorphous or matrix after milling for 12 hours. These amorphous matrices became crystalline phases after annealing at high temperatures as expected, but the original microstructure did not change significantly

Amino acid transporters play an important role in supplying organic nutrient to cells. The expression of L-type arnino acid transporter 1 (LATl) and its subunit 4F2 heavy chain (4F2hc) was evaluated to deterrnine the alterations to these transporters in oral norrnal mucosa (ONM) , oral precancerous lesion (OPL) and oral squamous cell carcinoma (OSCC). Sections from formalin-ftxed, paraffm-embedded S따nples of ONM, OPL or OSCC were exarnined using immunohistochernical staining to detect LATl and 4F2hc proteins. 까le LATl and 4F강lC expression increased progressively from ONM to hypeφ，Iastic and to dysplastic lesions and OSCC. In partiαlar， LATl rnay be a more S야dftc indicator of tumor prog~않sion than 4F2hc. 까le gradually increasing LA Tl and 4F2hc expression detected during the multistep progressive change shows that the protein rnay have an important role in the early stages of multistep oral carcinogenesis. In addition, the specific inhibition of LA Tl and 4F2hc rnight be a new rationale to suppress oral cancer progression.

최근 강교량이나 선박과 같은 강구조물에 있어서 여러 가지 환경요인에 의해 균열 및 부식 등의 문제가 다수 발생되어지고 있다. 이러한 문제를 해결하기 위해 보수용접을 사용할 수 있다. 이러한 보수용접은 절단이라는 과정을 필연적으로 수반하고 있다. 따라서 이러한 절단 줄 얻어지는 잔류응력의 예측은 구조물의 안전이라는 측면에서 중요하다고 할 수 있다. 본 연구에서는 2차원 및 3차원 유한요소 해석을 수행하여 가스절단에 의해 얻어진 절단잔류응력을 구하였으며, 2차원 및 3차원 해석기법의 정도를 명확히 하였다. 2차원 및 3차원 해석을 수행하여 얻은 절단잔류응력의 분포 및 그 절대치는 유사한 값을 나타내었다.

(x=0.69~0.74) powders synthesized by the thermal decomposition of organic acid salts. The obtained powders were uniform in composition and ultra-fine particle with about 400 nm. The amount of spinel phase of these powders was about 50% in X-ray diffraction patterns. The calcination of powder was carried out at for 2 hours in air. After the powders were calcined. the mean size of powder was about 500 nm and the amount of spinel phase was increased over about 65%. The maximum amount of spinel phase was about 75% in the specimen of X=0.72. The magnetic properties of calcined powders were the best among the different among the different compositions