• Title/Summary/Keyword: GE matrix

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Influence of Ge addition on AC loss and micro-structure in $Nb_{3}Sn$ wires (Ge를 첨가한 Nb$_3$Sn 초전도 선에서의 교류손실 및 미세조직 변화)

  • 하도우;이남진;오상수;하홍수;송규정;권영길;류강식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.104-107
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    • 2001
  • In order to investigate the effect of Ge addition to the Cu matrix on the microstructure and the critical current density, four kinds of internal tin processed Nb$_3$Sn strands with pure Cu and Cu 0.2, 0.4, 0.6 wt % Ge alloys were drawn to 0.8 mm diameter. The microstructure and critical current of internal tin processed Nb$_3$Sn wires that were heat treated at temperatures ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$ for 240h were investigated. The Ge addition to the matrix did not make workability worse. A Ge rich layer in the Cu-Ge matrix suppressed the growth of the Nb$_3$Sn layer and promoted grain coarsening. The greater the Ge content in the matrix, the lower the net Jc result after Nb$_3$sn reaction heat treatment. There was no significant variation in Jc observed with heat treatment temperature ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$. The values of AC loss of Ge added wires were decreased to 40 % compare with no addition wire. Low AC loss was due to segregation of Ge rich layer in the Cu-Ge matrix. If Ge added wire with thin Nb filaments were fabricated, slow diffusion rate of Sn would be overcome and decreased AC loss that is weak Point of internal tin method.

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Influence of Ge addition on phase formation and electromagnetic properties in internal tin processed $Nb_3$Sn wires (내부 확산법에 의한 $Nb_3$Sn초전도선에 Ge 첨가에 따른 임계전류 및 미세조직 변화)

  • 하동우;오상수;이남진;하홍수;권영길;류강식;백홍구
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.496-499
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    • 2000
  • In order to investigate the effect of Ge addition to the Cu Matrix on the microstructure and the critical current density, four kinds of internal tin processed Nb$_3$Sn strands with pure Cu and Cu 0.2, 0.4, 0.6 wt% Ge alloy were drawn to 0.8 mm diameter. The microstructure and critical current of internal tin processed Nb$_3$Sn wires that were heat treated at temperatures ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$ for 240 h were investigated. The Ge addition to the matrix did not make workability worse. A Ge rich layer in the Cu-Ge matrix suppressed the growth of the Nb$_3$Sn layer and promoted grain coarsening. The greater the Ge content in the matrix, the lower the net Jc result after Nb$_3$Sn reaction heat treatment. There was no significant variation in Jc observed with heat treatment temperature ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$.

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Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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Effect of herbal extracts on bone regeneration in a rat calvaria defect model and screening system

  • Lee, Dong-Hwan;Kim, Il-Kyu;Cho, Hyun-Young;Seo, Ji-Hoon;Jang, Jun-Min;Kim, Jin
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.44 no.2
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    • pp.79-85
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    • 2018
  • Objectives: The aim of this study was to evaluate the effects of herbal extracts on bone regeneration. Two known samples were screened. Materials and Methods: We previously established a rat calvaria defect model using a combination of collagen scaffold and herbal extracts. An 8 mm diameter trephine bur with a low-speed dental hand piece was used to create a circular calvaria defect. The experimental group was divided into 4 classifications: control, collagen matrix, Danshen with collagen, and Ge Gan with collagen. Animals in each group were sacrificed at 4, 6, 8, and 10 weeks after surgery, and bone regeneration ability was evaluated by histological examination. Results: Results revealed that both Danshen and Ge Gan extracts increased bone formation activity when used with collagen matrix. All groups showed almost the same histological findings until 6 weeks. However, after 6 weeks, bone formation activity proceeded differently in each group. In the experimental groups, new bone formation activity was found continuously up to 10 weeks. In the Danshen and Ge Gan groups, grafted materials were still present until 10 weeks after treatment, as evidenced by foreign body reactions showing multinucleated giant cells in chronic inflammatory vascular connective tissue. Conclusion: Histological analyses showed that Danshen and Ge Gan extractions increased bone formation activity when used in conjunction with collagen matrix.

Cell Growing Behavior on the Electrospun PVA/GE nanofibermats.

  • Linh, Nguyen Thuy Ba;Nguyen, Thi-Hiep;Song, Ho-Yeon;Yang, Hun-Mo;Min, Young-Ki;Lee, Byong-Taek
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2009.11a
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    • pp.41.2-41.2
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    • 2009
  • Electrospinning of Polyvinylalcohol (PVA), Gelatin (GE), and PVA/GE blend solutions in acetic acid were investigated to fabricate biodegradable for tissue engineering. The morphology of the electrospun nanofibers was investigated with a field emission scanning electron microscope. The fibers have average diameters in the range 50-150 nm. The miscibility of PVA/GE blend fibers was examined by differential scanning calorimetry.The PVA and GE were immiscible in the as-spun nanofibrous structure. X-ray diffraction (XRD) determined the crystallinity of the membrane and tensile strength for evaluation physical properties. An in vitro study of PVA/GE blend nanofibers was conducted. To assay the cytocompatibility and cell behavior on the PVA/GE blend nanofibrous scaffolds, cell attachment and spreading of fibroblasts seeded on the scaffolds were studied. Our results indicate that thePVA/GE blend nanofibrous matrix, particularly the one that contained 20% PVA and 80% GE could be a good candidate for tissue engineering scaffolds, because it has an excellent cell attachment and spreading for fibroblast cell.

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Study on Synthesis of 68GeO2 and Behavior of 68Ga3+ for Generator Column (Generator 컬럼용 68GeO2 합성 및 68Ga3+의 거동에 관한 연구)

  • Kim, Gun Gyun;Lee, Jun Young;Kim, Sang Wook;Hur, Min Gu;Yang, Seung Dae;Park, Jeong Hoon
    • Journal of Radiation Industry
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    • v.10 no.4
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    • pp.189-192
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    • 2016
  • $^{68}Ga$ has emerged as a promising candidate for non-invasive diagnostic imaging within Positron Emission Tomography (PET) because of its advantageous radiochemical characteristics ($t_{1/2}=68min$, ${\beta}^+$ yield ~89%). $^{68}Ga$ forms a stable chelation with various ligands and it is possible to be quickly and easily study using a $^{68}Ge/^{68}Ga$ generator. Commercial $^{68}Ge/^{68}Ga$ generators are chromatographic system using the inorganic materials such as alumina and tin dioxide which are employed as column matrixes for $^{68}Ge$. In this study, we tried out to make $^{68}Ge/^{68}Ga$ generator system with the $^{68}GeO_2$ microstructures for column matrix. $^{68}Ge$ tends to have stable bond with oxide as $^{68}GeO_2$ microstructures. The $^{68}GeO_2$ has been synthesized by hydrolysis of $GeCl_4$ (sol-gel method) and characterized by X-ray diffraction and scanning electron microscope for geometrical analysis. The stability of $GeO_2$ was tested using eluents with diverse solvents(water, ethanol and 0.1 N HCl). The radioactivity of $^{68}Ga^{3+}$ in eluate through $GeO_2$ was measured to prove a function as column material for a generator.

Structural properties of GeSi/Si heterojunction compound semiconductor films by using SPE (SPE법을 통해 형성된 $Ge_xSi_{1-x}/Si$이종접합 화합물 반도체의 결정분석)

  • 안병열;서정훈
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.3
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    • pp.713-719
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    • 2000
  • In order to Prepare the$Ge_xSi_{1-x}/Si$(111) heterosructure by solid phase epitaxy (SPE), about 1000A of Au and about 1000A Ge were sequentially deposited on the Si(111) substrate. The resulting Ge/Au/Si(111) samples were isochronically annealed in the high vacuum condition. The behaviors of Au and Ge during thermal annealing and the structural Properties of $Ge_xSi_{1-x}$ films were characterized by Auger electron spectroscopy (AES), X-ray diffraction (XRD) and high resolution transmission electron microscopy (TEM). The a-Ge/Au/Si(111) structure was converted to the Au/GeSi/Si(111) structure. Defects such as stacking faults, point defects and dislocations were found at the GeXSil-X(111) interface, but the film was grown epitaxially with the matching face relationship of $Ge_xSi_{1-x}/$(111)/Si(111). Twin crystals were also found in the $Ge_xSi_{1-x}/$(111) matrix.

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INTERSECTIONS OF MAXIMAL FACES IN THE CONVEX SET OF POSITIVE LINEAR MAPS BETWEEN MATRIX ALGEBRAS

  • Kye, Seung-Hyeok;Lee, Sa-Ge
    • Communications of the Korean Mathematical Society
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    • v.10 no.4
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    • pp.917-924
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    • 1995
  • Let $P_I$ be the convex compact set of all unital positive linear maps between the $n \times n$ matrix algebra over the complex field. We find a necessary and sufficient condition for which two maximal faces of $\cap P_I$ intersect. In particular, we show that any pair of maximal faces of $P_I$ has the nonempty intersection, whenever $n \geq 3$.

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Preparation and Pharmacokinetic evaluation of Captopril Matrix Tablets with Polyethylene Oxide (폴리에틸렌옥시드를 이용한 캅토프릴 매트릭스 정제의 제조 및 약물동력학적 평가)

  • Jiang, Ge;Baek, Myoung-Ki;Jee, Ung-Kil
    • Journal of Pharmaceutical Investigation
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    • v.29 no.1
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    • pp.7-12
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    • 1999
  • The captopril matrix tablets composed of polyethylene oxide(PEO) was prepared and administered to beagle dogs. Captopril matrix tablets were prepared using direct compressed method and wet granulation compressed method with various ratios of drug to PEO. The diffusion rate of captopril matrix tablets followed on the Higuchi's diffusion model. With increasing hardness of captopril matrix tablets, release rate was decreased. Each formulation was evaluated by the area under the curve (AUC) and time course of plasma captopril concentration after oral administration to beagle dogs. The $AUC_{0-12}$ were $9.126\;{\mu}g\;h/ml$ and $6.417\;{\mu}g\;h/ml$ for the matrix tablets and conventional tablets, respectively. Therefore, the bioavailability of captopril matrix tablets was greater than that of commercial product. It is suggested that captopril matrix tablets using PEO is a useful sustained release formulation.

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The Matrix Effect of Biological Concomitant Element on the Signal Intensity of Ge, As, And Se in Inductively Coupled Plasma/Mass Spectrometry

  • Park, Kyung-Su;Kim, Sun-Tae;Kim, Young-Man;Kim, Yun-je;Lee, Won
    • Bulletin of the Korean Chemical Society
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    • v.23 no.10
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    • pp.1389-1393
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    • 2002
  • The non-spectroscopic interference effects that occurred in inductively coupled plasma/mass spectrometry were studied for Ge, As and Se in human urine and serum. Many biological samples contain Na, K, Cl and organic compounds, which may cause the enhancement and depression on the analyte signal. The effect of 1% concomitant elements such as N, Cl, S, P, C, Na, and K on a 100 ㎍/L germanium, arsenic and selenium signal has been investigated by ICP/MS. The interference effects were not in the same direction. It appeared that concomitant elements such as Cl, S, and C induce an enhancement effect, whereas N and P did not show any significant effect. And, Na and K caused a depression. We have found a link between the abundance of analytes and the ionization potential of concomitant elements (eV), except carbon and nitrogen.