• Title/Summary/Keyword: Ag

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Growth Factors of Hyphal Anastomosis Groups of Rhizoctonia solani Kuhn I. Effects of Temperature, pH, Carbon and Nitrogen Sources (Rhizoctonia solani의 균사융합군별 생장요인 I. 온도, PH, 탄소원 및 질소원의 영향)

  • Kim Hyung Moo
    • Korean Journal Plant Pathology
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    • v.1 no.1
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    • pp.72-78
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    • 1985
  • The effects of temperature. pH, carbon and nitrogen sources on the growth of Rhizoctonia solani were studied by using five hyphal anastomosis groups(four cultural types, 7 isolates) of the fungus. The ranges of optimum temperature were $20^{\circ}C$ in the AG 2-1, AG 2-2 and AG 4, and $25^{\circ}C$ in the AG 1-IA, AG 1-IB, AG 3, AG 5. The optimum pH for the mycelial growth was 6-7 in the fungus. Glucose in the AG 1-lA, AG 1-IB, AG 2-2, AG 3 and AG 5, sucrose in the AG 2-1 and fructose in the AG 4 were the most effective for the mycelial growth, but glycerine, cellulose and lactose were not effectively utilized as nutrients. $Ca(NO_3)_2$ in the AG 1-IA, AG 1-IB and AG 4, asparagine in the AG 2-1, $KNO_3$ in the AG 2-2 and $NaNO_3$ in the AG 5 were the best nitrogen sources for the mycelial growth, but $NH_4NO_3$ was not easily utilized by the fungus. Nitrate and organic nitrogens for the fungal growth were utilized better than ammonium nitrogen.

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Sequential Analysis of Hepatitis Be Antigen Status in Infants Born to Hepatitis Be Antigen-Positive Mothers (HBe항원 양성 산모에서 출생한 HBe항원 양성인 신생아의 추적관찰)

  • Park, Eun Sook;Lee, Hae Kyung;Oh, Chang Hee;Kim, Sung Ku;Yun, Hae Sun;Song, Won Keun;Lee, Young Ah
    • Clinical and Experimental Pediatrics
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    • v.45 no.6
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    • pp.727-731
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    • 2002
  • Purpose : The objectives of this study are to evaluate the significance of HBeAg positivity in infants born to HBeAg and HBsAg positive mothers. Methods : The HBeAg status of 22 HBeAg positive, HBsAg negative infants born to HBeAg and HBsAg positive mothers from December 1996 to March 1999 were evaluated by enzyme immunoassay. Results : The number of HBsAg positive carrier mothers was 213(4.9%) out of 4,338 pregnant women. HBeAg was positive in 76(41.5%) out of 183 HBsAg positive mothers. Only 49 infants born to 76 HBeAg positive mothers could be evaluated; 36 infants were HBeAg positive and HBsAg negative. Laboratory follow up was possible in 22 infants. HBeAg disappeared in 7 cases within two months and in 20 cases within 12 months(over 90%). Ultimately, twenty-two babies who were HBsAg-negative and HBeAg-positive became negative for HBeAg, however, one showed HBsAg in follow up of 6 months of age. Conclusion : HBeAg positivity in infants born to HBeAg positive mothers may result from the maternofetal transmission and this HBeAg eventually disappeared without clinical significance.

Anastomosis Groups and Cultural Characteristics of Rhizoctonia solani Isolates from Crops in Korea (국내(國內) 작물(作物)에서 분리한 Rhizoctonia solani 균주(菌株)들의 균사융합군(菌絲融合群)과 배양적(培養的) 특성(特性))

  • Kim, Wan-Gyu;Cho, Won-Dae;Lee, Young-Hee
    • The Korean Journal of Mycology
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    • v.22 no.4
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    • pp.309-324
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    • 1994
  • A total of 2,276 isolates of Rhizoctonia solani obtained from diseased crops of 68 species was classified into anastomosis groups AG-1, AG-2-1, AG-2-2, AG-3, AG-4 and AG-5 by anastomosis test. Among the isolates, 1,091 isolates were identified as AG-1, 326 isolates as AG-2-1, 191 isolates as AG-2-2, 71 isolates as AG-3, 505 isolates as AG-4, and 92 isolates as AG-5. Among the isolates of AG-1, 791 isolates were grouped as cultural type IA, 280 isolates as cultural type IB, and the others as cultural type IC. Among the isolates of AG-2-2, 112 isolates were grouped as cultural type IIIB, and the others as cultural type IV. Cultural types IA, IB and IC of AG-1 were isolated from 7, 26 and 2 species of crops, respectively. AG-2-1 was isolated from 10 species of crops. Cultural types IIIB and IV of AG-2-2 were isolated from 7 and 3 species of crops, respectively. AG-3 was only isolated from Solanum tuberosum. AG-4 was isolated from 43 species of crops, and AG-5 from 13 species of crops. A single anastomosis group was isolated from each of 45 species of crops, but two or more than two anastomosis groups were isolated from each of the other crops. Cultural appearance of the isolates belonging to an anastomosis group or a cultural type was mostly distinct from that belonging to others, although cultural appearances of some anastomosis groups or cultural types were similar to one another. Optimum temperature for mycelial growth of AG-1, AG-2-2, AG-4 and AG-5 ranged from 26 to $30^{\circ}C$, and that of AG-2-1 and AG-3 from 22 to $26^{\circ}C$. Minimum temperature for mycelial growth of AG-2-1 was the lowest as $2{\sim}3^{\circ}C$, that of AG-1(IA) and AG-4 was the highest as $10{\sim}11^{\circ}C$, and that of the others ranged from 5 to $10^{\circ}C$. Maximum temperature for mycelial growth of AG-2-2(IIIB) was the highest as $36{\sim}37^{\circ}C$, that of AG-2-1 was the lowest as $29{\sim}30^{\circ}C$, and that of the others ranged from 31 to $36^{\circ}C$. When the mycelial growth rates at $26^{\circ}C$ were compared, AG-1(IC) grew most rapidly, followed by AG-1(IA) and AG-1(IB), and AG-2-1 grew most slowly.

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Fabrication of Poly(ethylene oxide)/Ag Nanoparticles/p-benzoquinone Composite Membrane Using AgNO3 Precursor for Olefin/Paraffin Separation (올레핀/파라핀 분리용 AgNO3 전구체를 활용한 poly(ethylene oxide)/Ag nanoparticles/p-benzoquinone 복합체 분리막 제조)

  • kim, Minsu;Kang, Sang Wook
    • Membrane Journal
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    • v.28 no.4
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    • pp.260-264
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    • 2018
  • Poly (ethylene oxide) (PEO)/Ag nanoparticles (AgNPs)(precursor : $AgBF_4$)/p-benzoquinone (p-BQ) composite membrane was prepared for olefin/paraffin separation. As a result, the performance of composite membrane was observed to be maintained at selectivity of 10 and permeance of 15 GPU up to 100 hours. The performance of the membrane was maintained for 100 hours was attributable to that Ag ions could be converted into stable Ag NPs by addition of p-BQ. Furthermore, the surface was partially polarized by the electron acceptor p-BQ, resulting in the formation of olefin carrier. In this study, since the cost of $AgBF_4$ used as a precursor of Ag NPs was relatively higher, $AgNO_3$ was utilized. As a result, it was confirmed that $AgNO_3$ couldn't show the stable formation of nanoparticle, resulting in the poor separation performance.

A Study of Strength, Fracture Toughness and Superconducting Properties of YBCO-Ag Composite Superconductors (YBCO-Ag 복합초전도체의 강도, 파괴인성 및 초전도성질에 관한 연구)

  • Joo, Jin-Ho;Ur, Soon-Chul
    • Korean Journal of Materials Research
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    • v.8 no.5
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    • pp.394-398
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    • 1998
  • We have studied the effect of Ag additions on the microstructure and the related mechanical and supercon¬ducting properties of $ YBa_{2}$$Cu_{3}$$O_{7-\delta}$ (YBCO) superconductors. A 5-15 vol.% of Ag was added to YBCO in the forms of Ag and $AgNO_{3}$, powder and the resultant microstructural evolution was evaluated. It was observed that the strength and fracture toughness of YBCO increased with increasing Ag content. These improvements in strength and fracture toughness are believed to be due to the strengthening mechanisms caused by the presence of Ag. In addition, YBCO-Ag composite superconductors showed higher values of strength and fracture toughness when Ag was added in the form of AgNO, than those of which was added Ag. The higher mechanical properties of YBCO- Ag resulting from $AgNO_{3}$, addition are probably due to the microstructure of more finely and uniformly distributed Ag particles. The addition of Ag also showed slightly improved critical current density of YBCO superconductors.

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Optical Properties of All Solution processed ZnO/Ag/ZnO Multilayers (용액공정으로 제작한 ZnO/Ag/ZnO 다층구조의 광학적 특성 연구)

  • Lee, Hyungin;Kim, Jiwan
    • Journal of the Microelectronics and Packaging Society
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    • v.25 no.4
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    • pp.119-122
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    • 2018
  • Various ZnO/Ag/ZnO multilayers were fabricated and their optical properties were investigated. Top and bottom ZnO layers were formed by sol-gel method and mid-metal layers were deposited by spin coating. To find suitable deposition condition of Ag, we measure thickness and sheet resistance of Ag monolayer. After the optimization of Ag monolayer, we fabricate ZnO/Ag/ZnO multilayers. Transmittance of ZnO/Ag/ZnO multilayers increased to 63%. In near IR region, transmittance of ZnO/Ag/ZnO multilayers decreased to 35% when the concentration of Ag solution was 2.5wt%.

Mechanical and Electrical Reliability of Silver Nanowire Film on Flexible Substrate (유연기판 위에 제작된 Silver Nanowire 필름의 기계 및 전기적 신뢰성 연구)

  • Lee, Yo Seb;Lee, Won Jae;Park, Jin Yeong;Choa, Sung-Hoon
    • Journal of the Microelectronics and Packaging Society
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    • v.23 no.4
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    • pp.93-99
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    • 2016
  • In this paper, we investigated the mechanical and electrical reliability of silver nanowire (AgNW) films. In particular, the durability and reliability of AgNW films were studied when the AgNW film was subjected to the bending deformation under current flow. The electrical durability of AgNW was evaluated by observing changes in heat generation and current density occurring in AgNW through voltage and current tests. The AgNW film showed a constant resistance change up to a bending radius of 2 mm and 200,000 cycles in the bending fatigue tests. The over-coating layer has an effect of improving the durability of the AgNW film. In the case of AgNW with the over-coating layer, heat was uniformly dissipated on the surface of AgNW film, whereas in the case of AgNW film without the over-coating layer, heat was generated locally. In the bending test under the current flow, the current density of the AgNW film was continuously decreased up to 52.4%. During bending, the AgNW was deformed due to mechanical deformation such as tensile, bending and sliding of the AgNW, consequently contact resistance of the AgNW was increased, leading to a electrical breakdown of AgNW by Joule heating. It was found that the application of the over-coating layer can improve the electrical and mechanical reliability of the AgNW film.

Relative Influence of Sediments, Food and Dissolved Sources on Ag Bioaccumulation in the Amphipod Leptocheirus plumulosus (오염된 퇴적물로부터 해양저서 단각류 Leptocheirus plumulosus의 은(Ag)축적에서 흡수경로의 상대적 기여도 평가)

  • Yoo, Hoon;Lee, In-Tae;Lee, Byeong-Gweon
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.7 no.2
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    • pp.87-93
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    • 2002
  • A amphipod, Leptocheirus plumulosus was exposed to Ag contaminated sediments to evaluate relative importance of various uptake routes (sediment, porewater, supplementary food) for Ag bioaccumulation in sediment-dwelling marine invertebrates. Additionally, influence of AVS (acid-volatile sulfide) on the partitioning of Ag to porewater and on the Ag bioavailability was determined to evaluate the utility of AVS criteria for the management of metal contaminated sediment. The experimental sediments were spiked with 4 levels of Ag (0.1-3.3 ${\mu}$mol Ag/g) and AVS concentrations were manipulated to 40 or <0.5 ${\mu}$mol/g, then equilibrated for >2 months to allow pore water/particulate distributions similar to nature. A L. plumulosus was incubated in the contaminated sediments with overlying water for 35d. During the exposure, the amphipods was fed with supplementary food ($TetraMin^{(R)}$) with or without Ag contamination. Following exposure, tissue Ag in L. plumulosus was strongly correlated with the weak acid extractable Ag in sediments ($r^{2}$=0.87, p<0.001). The ratio of AVS to Ag-SEM (Ag extracted simulaneouls with AVS) had a strong influence on porewater Ag concentration, consistent with previous studies. However, Ag bioaccumulation in L. plumulosus was not influenced by AVS concentrations. The amphipods fed Ag contaminated food took up ${\sim}$ 1.8 X Ag accumulated by the amphipods fed uncontaminated supplementary diet. The result suggests that the benthic invertebrates exposed to metal contaminated sediments would accumulate metals largely via ingestion of contaminated sediments and food, with minor contribution from dissolved sources of porewater and overlying water.

Contact Formation Between Ag and Si With Lead-Free Frits in Ag Pastes For Si Solar Cells (실리콘 태양전지용 Ag pastes 에서의 무연 프릿에 따른 Ag, Si간 접촉 형성)

  • Kim, Dongsun;Hwang, Seongjin;Kim, Jongwoo;Lee, Jungki;Kim, Hyungsun
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.61.2-61.2
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    • 2010
  • Ag thick-film has usually been used for the front electrode of Si solar cells with the outstanding electrical properties. Ag paste consists of Ag powers, vehicles, frits and additives. Ag paste has broadly been screen-printed on the front side of Si wafer with the merits of low cost and simplicity. The optimal contact formation between Ag electrodes and Si wafer in the front electrode during a fast firing has been considered as the key factor for high efficiency. Although the content of frit in Ag pastes is less than 5wt%, it can profoundly influence the contact formation between Ag and Si under the fast firing. In this study, the effects of lead-free frits on the contacts between Ag and Si were studied with the thermal properties and compositions of various frits. Our experimental results showed that the electrical properties of cells were related to the interface structures between Ag and Si. It was found that current path of electrons from Si to Ag would be possible through the tunneling mechanism assisted by tens of nano-Ag recrystals on $n^+$ emitter as well as Ag recrystals penetrated into $n^+$ emitter layers. These preliminary studies will be helpful for designing the proper frits for the Ag pastes with considering the properties of various Si wafers.

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Synthesis and Characterization of the Ag-doped TiO2

  • Lee, Eun Kyoung;Han, Sun Young
    • Elastomers and Composites
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    • v.57 no.1
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    • pp.1-8
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    • 2022
  • In this study, the photo-deposition method was used to introduce Ag onto the surface of TiO2 to synthesize an Ag-TiO2 composite. The effects of the varying amounts of AgNO3 precursor and annealing time periods on the Ag content in the composites, as well as their antibacterial characteristics under visible light conditions were studied. SEM analysis revealed the spherical morphology of the Ag-TiO2 composite. Compared with TiO2, the Ag particles were too small to be observed. An XPS analysis of the Ag-TiO2 surface confirmed the Ag content and showed the peak intensities for elements such as Ag, Ti, O, C, and Si. The highest Ag content was observed when 33.3 wt.% of AgNO3 and an annealing time of 6 h were employed; this was the optimum annealing time for Ti-Ag-O bonding, in that the lowest number of O bonds and the highest number of Ag bonds were confirmed by XPS analysis. Superior antibacterial properties against Bacillus and Escherichia coli, in addition to the widest inhibition zones were exhibited by the Ag-TiO2 composite with an increased Ag content in a disk diffusion test, the bacterial reduction rate against Staphylococcus aureus and Escherichia coli being 99.9%.