• Progress in Superconductivity
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• 제8권1호
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• pp.119-121
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• 2006

We studied the mechanical and magnetic properties of Y-Ba-Cu-O superconductor with and without resin and Ag impregnation. Bulk YBCO superconductor was manufactured with the top-seeded melt-growth method. Typical sample of 40mm X 20mm X 3mm was made and then 8 holes with 0.5mm diameter were drilled arbitrally. Epoxy resin and $AgNO_3$ were systematically added into the holes to compare the mechanical and magnetic properties of YBCO superconductor before and after reinforcement of resin and Ag. Based on the result of 3 point bending, bending strength increased with increasing amounts of resin and carbon nano-tube. However, it was found that the levitation force decreased after making hole, compared with virgin sample without hole.

• 한국분말재료학회지
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• 제11권6호
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• pp.477-485
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• 2004

Monodispersed flaky silver powder was obtained by controlling the ratios of $H_{2}O_{2}/NH_{3}$ and Agin in a mixed solution of ethylene glycol and ammonia with an addition of PVP. The effects of $NH_{3}/Ag,\; H_{2}O_{2}/Ag\;and\;H_{2}PtCl_{6}/Ag$ on its morphology and size were investigated. In $H_{2}O_{2}-NH_{3}-AgNO_{3}\;system,\;NH_{3}/Ag$ molar ratio was found to be an important reaction factor for the nucleation and crystal growth of Ag powder. The synthesis of flaky powder was optimized at over 6 of $NH_{3}/Ag \;and\;5\;of\;H_{2}O_{2}/Ag\;under\;1.0{\times}10^{-3}\;of\;Pt/Ag.\;Moreover,\;as\;the\; NH_{3}/Ag$ molar ratio increased, the size of precipitates was increased regardless of the amount of Pt. In the absence of $H_{2}PtCI$, the morphology and size of reduced Ag powder were found to be irregular in shape $2-4{\mu}m$ in diameter. However, homogenized fine Ag powder was obtained due to heterogeneous nucleation when $H_{2}PtCI$ used as a cat-alyst, and flaky one was synthesized with the addition of Pt over $1.0{\times}10^{-3}$ of Pt/Ag.

• Journal of Plant Biotechnology
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• 제48권3호
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• pp.173-178
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• 2021

Basal callus formation and leaf abscission is a problem in clonal micropropagation. We have described an in vitro clonal propagation protocol of Dalbergia sissoo Roxb (shisham) 'FRI-14' in which AgNO₃ played important role not only in mitigating problem of leaf abscission and basal callus, but also improved shoot induction and multiplication. Best induction and shoot multiplication was obtained on MS media with 1.5 mg/l 6-BAP and 10 mg/l AgNO₃ and half-strength MS media with 0.5 mg/l 6-BAP, 2 mg/l AgNO₃ and 50 mg/l Adenine sulphate whereas best ex vitro rooting was obtained with 200 mg/l IBA in pulse treatment.

• 대한화학회지
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• 제40권7호
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• pp.474-482
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• 1996

$Ag^+$ 이온으로 완전히 치환되고 탈수된 두개의 제올라이트 X의 구조(a=24.922${\AA}$, a=24.901(1)${\AA}$)를 21$^{\circ}C$에서 입방공간군 Fd3을 사용하여 단결정 X-선 회절법으로 해석하고 구조를 정밀화하였다. 결정은 $AgNO_3$의 수용액을 사용하여 3일간 흐름법으로 이온 교환하였다. 첫번째 결정은 300$^{\circ}C$에서 $2{\times}10^{-6$torr하에서 2일간 진공 탈수하였다. 두번째 결정은 350$^{\circ}C$에서 진공 탈수하였다. 첫번째 구조는 Full-matrix 최소자승법 정밀화 계산에서 I>3${\sigma}$(I)인 227개의 독립 반사를 사용하여 최종 오차 인자를 $R_1=0.095,\;R_2=0.092$까지 정밀화 계산하였고, 두번째 구조는 334개의 독립 반사를 사용하여 $R_1=0.096,\;R_2=0.087$까지 정밀화시켰다. 첫번째 결정에서 Ag는 서로 다른 5개의 결정학적 자리에 위치하였다. 16개의 $Ag^-$이온은 D6R의 중심에 있는 자리 I를 채우면서 위치하고, 32개의 Ag원자는 D6R의 맞은편에 있는 소다라이트 공동에 있는 자리 I'에 위치하였고, 17개의 $Ag^+$ 이온은 큰 공동에 있는 6-산소 링에서 소다라이트 공동 내의 32-중축을 가진 II'에 위치하고, 15개의 $Ag^+$ 이온은 큰 공동에 32-중축을 가진 II에 위치하고, 나마지 12개의 $Ag^+$이온은 2중축을 약간 벗어난 큰 공동에 있는 III'에 위치하였다. 두번째 결정에서 모든 Ag종은 첫번째 결정과 유사한 자리에 있었다. 자리 I에 16개, 자리 I'에 28개, 자리 II에 16개, 자리 II'에 16개, 자리 III에 6개 또 다른 III'에 6개 모두 88개의 Ag종이 위치하였고 4개의 Ag원자는 탈수중에 골조 밖으로 이동하였다. 이들 결정에서 Ag원자는 소다라이트 공동의 중심에서 사면체의 $Ag_4$ 클라스터를 형성하였다. 이 클라스터는 2개의 $Ag^+$이온과 배위하여 안정화 된다. 클라스터에서 Ag-Ag 거리는 약 3.05.angs.이고 은금속에서 Ag-Ag 거리인 2.89.angs.보다 약간 길었다. 소다라이트 공동에 위치한 자리II에서 적어도 2개의 6-링에 위치한 $Ag^+$이온은 클라스터에 반드시 배위하며, 뒤틀린 팔면체 은 클라스터인($Ag_6)^{2+}$)로 존재한다.

• Bulletin of the Korean Chemical Society
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• 제8권2호
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• pp.69-72
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• 1987

The structures of dehydrated $Ag_9Cs_3$-A treated with hydrogen gas at three different temperatures have been determined by single-crystal X-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at 23(1) $^{\circ}C$. All crystals were ion exchanged in flowing streams of aqueous $AgNO_3$/$CsNO_3$ with a mole ratio 1:3.0 to achieve the desired crystal composition. The structures treated with hydrogen at $23^{\circ}C(a=12.288(1)\;{\AA})\;and\;310^{\circ}C(a=12.291(2)\;{\AA})$ refined to the final error indices R1 = 0.091 and R2 = 0.079, and 0.065 and 0.073, respectively, using the 216 and 227 reflections, respectively, for which I >3${\sigma}$(I). In both of these structures, eight $Ag^+$ ions are found nearly at 6-ring centers, and three $Cs^+$ ions lie at the centers of the 8-rings at sites of $D_{4h}$ symmetry. One $Ag^{\circ}atom$, presumably formed from the reduction of a $Ag^+$ ion by an oxide ion of a residual water molecule or of the zeolite framework during the dehydration process, is retained within the zeolite, perhaps in a cluster. In these two structures hydrogen gas could not enter the zeolite to reduce the $Ag^+$ ions because the large $Cs^+$ ions blocked all the 8-windows. However, hydrogen could slowly diffuse into the zeolite and was able to reach and to reduce about half of the $Ag^+$ ions in the structure only at high temperature ($470^{\circ}C$). The silver atoms produced migrated out of the zeolite framework, and the protons generated led to substantial crystal damage.

• 원예과학기술지
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• 제18권6호
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• pp.834-838
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• 2000

연구는 삼지구엽초에 기내 다랑증식체 계의 설정을 위한 일환으로 절편체 별 살균방법, 생장조절제 종류 및 농도에 의한 캘루스의 증식과 배지를 달리한 식물체 분화 조건을 구명하고자 수행하여 얻어진 결과 진균과 박테리아에 의한 감염률은 근경의 정아와 액아에서 0.1% $AgNO_3$ 용액에 60분간 침지한 1차 살균 후 0.3% NaOCl 용액에 20분간 2차 살균한 처리가 가장 낮았으며 잎에서는 모든 처리에서 거의 오염이 발생되지는 않았지만 74% 이상이 고사되었다. 식물체 분화는 당년간 지하부에서 자란 근경의 정단이 0.1% $AgNO_3$ 용액에 30-60분간 침지한 1차 살균 후 0.3% NaOCl 용액에 20분간 2차 침지살균한 처리에서 가장 높았으며 1년 이상 지하부에서 자란 근경의 액아는 0.1 % $AgNO_3$ 30분간 1차 살균 후 0.3% NaOCl에 20분간 2차 살균한 처리에서 식물체 분화가 높았지만 callus와 식물체 분화는 0.1% $AgNO_3$ 60분간 1차 살균 후 0.3% NaOCl에 20분간 2차 살균한 처리에서 가장 높았다. 잎은 0.2% $AgNO_3$ 15분간 1차 살균 후 0.3% NaOCl 에 20분간 2차 살균한 처리에서 캘루스 유도율이 가장 높았다. 계대배양시 캘루스 생장은 변형된 1/2 MS 배지에 BA $0.02-0.2mg{\cdot}L^{-1}$과 NAA $2.0mg{\cdot}L^{-1}$ 혼용첨가한 처리에서 증식률이 가장 높았다. 캘루스로부터 식물체분화는 대부분 캘루스 상태로 증식되고 일부는 엽육조직으로 분화되었지만 1/2 UM 배지와 1/2 SH 배지에서 각각 8%와 3%가 식물체로 분화되었다

• 한국미생물·생명공학회지
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• 제23권1호
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• pp.104-109
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• 1995

The gene responsible for dechlorination of 4-chlorobenzoate (4CBA) was cloned in E. coli XL1-Blue from Pseudomonas sp. DJ-12. The cloned cell of E. coli Cjl had the hybrid pBluescript SK(+) plasmid, into which about 9.5 kb genomic DNA fragment of PseudOmonas sp. DJ-12 was inserted. The subclone of pCJlOl was constructed by inserting the 3.4 kb EcoRI-HindIII fragment of pCJl into the vector. Those cloned cells could be simply selected by halo formation around the colonies which was the precipitate of AgCl produced by reaction of AgNO$_{3}$ and chloride ion liberated by bacterial dechlorination of 4CBA- Such a plate assay method was standardized by the procedure that the colonies grown for 2 days on the Cl$^{-}$-free plate medium containing 1 mM 4CBA were flooded with 0.1 M AgNO$_{3}$ solution.

• 대한의생명과학회지
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• 제24권1호
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• pp.30-34
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• 2018

Silver (Ag) has been widely used in commercial products and medical fields since ancient times because of its antibacterial effect. It is harmless and non-toxic to the human body. For this reason, recent research has actively evaluated antimicrobial activity using silver (Ag). In this study, we investigated the inhibitory effect of a silver-based compound, silver phosphate ($Ag_3PO_4$) on the growth of Staphylococcus aureus and the activation of human immunity. First, the inhibitory effect of $Ag_3PO_4$ on the growth of Staphylococcus aureus was confirmed by a growth curve and a colonyounting method. As a result, the growth inhibitory effect increased as the concentration of $Ag_3PO_4$ increased. Specifically, treatment with $5{\mu}g/mL$ of $Ag_3PO_4$ resulted in no bacteria growth, and the colony-counting method showed a remarkable inhibition. In addition, the expression of cytokine IL-8 by $Ag_3PO_4$ was examined to investigate the cellular immune system activation by $Ag_3PO_4$. After pretreatment of Staphylococcus aureus for 1 hour with $50{\mu}g/mL$ $Ag_3PO_4$, an increased IL-8 mRNA expression resulted. In cells treated with $Ag_3PO_4$, we found that the expression of IL-8 was enhanced in a time-dependent fashion compared to non-treated cells. These results indicate that $Ag_3PO_4$ induces antimicrobial activity against Staphylococcus aureus and activates human immunity. These results are expected to contribute to the future study of the mechanism of silver (Ag) and silver-based compounds in relation to antibacterial activity.

• 식물조직배양학회지
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• 제22권5호
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• pp.267-271
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• 1995

배추의 기내재분화율을 향상시키기 위하여 자엽을 치상재료로 하여 에틸렌 억제제인 AgNO$_3$와 STS를 첨가하여 그 영향을 조사하였다. AgNO$_3$의 경우에는 100 $\mu$M이 첨가되었을 때 STS에서는 5 $\mu$M이 첨가되었을 때, 무처리구의 4%, 2%에 비해 각각 가장 높은 22%와 15.3%의 재분화율을 보였다. 자엽연령에 대해서는 파종 후 3일 지난 자엽을 사용하였을 때 58%의 재분화율을 나타내었다. 배양용기에 따른 효과는 1회용 페트리디쉬에서 가장 높았으나 처리간에 뚜렷한 차이는 없었다. 뿌리유기 조건은 생장조절제가 포함되지 않은 처리와 NAA가 0.1 mg/L 농도로 첨가된 배지에서 가장 좋은 결과를 얻었으며 그 형태 및 밀도, 활력에서 가장 우수하였다. 기내에서 뿌리가 형성된 식물체를 4$^{\circ}C$에서 4주간 처리하여 추대를 유기하였고 형태적으로 정상적인 화기를 볼 수 있었으며 이들로부터 종자를 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.273-276
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• 2011

Uniform Ag nanoparticles (< 10 nm) were effectively prepared in 1-amino-4-methylpiperazine as a solvent with multiple functions including reduction and stabilization. An Ag-complex such as $Ag_2(ehac)_2(eha)_2$ (ehac = 2-ethylhexylammonium carbamate; eha = 2-ethylhexylamine) was used as an Ag-precursor, whereas the usage of a salt such as $AgNO_3$ showed the formation of Ag nanoparticles in larger and irregular size (30 - 500 nm). The Ag nanoparticles (< 10 nm) prepared by using the Ag-complex could also be effectively stabilized by 1-amino-4-methylpiperazine. Transmission electron micrographs confirmed that the Ag particles were spherical and in the nanometer size.