• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.377-377
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• 2010

The $AgInS_2$ epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. After the as-grown $AgInS_2$/GaAS was annealed in Ag-, S-, and In-atmosphere, the origin of point defects of the $AgInS_2$/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of $V_{Ag}$, $V_s$, $Ag_{int}$, and $S_{int}$ obtained from PL measurement were classified to donors or acceptors type

• Resources Recycling
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• v.21 no.6
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• pp.74-81
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• 2012

The Influence of temperature on the recovery reaction of silver in aqueous solution was investigated based on Pourbaix diagram constructed by thermodynamic calculation at different temperatures. It was observed that the stability of water is more strongly affected by pH variation and the stable region of ${Ag^+}_{(aq)}$ is diminished at higher temperature. It was shown that the recovery of $Ag_{(aq)}$ in the forms of $Ag_{(s)}$ and $Ag_2O_{3(s)}$ is more advantageous thermodynamically at lower temperature, however, the recovery of $Ag_{(aq)}$ in the forms of $Ag_2O_{(s)}$ 및 $Ag_2O_{2(s)}$ is more advantageous as temperature increases. The rise of temperature is considered to demote the recovery of silver thermodynamically in strong acidic condition ($pH{\leq}2$), but more silver is regarded to be recovered with temperature above pH 2. Finally, The recovery of silver in the elemental state is shown to be more sensitively influenced by temperature variation compared with the recovery of silver in its oxide form.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.461.1-461.1
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• 2014

본 연구진에서는 기존에 Ag2S 양자점을 흡광층으로 활용하여 양자점 감응형 태양전지(QDSC)를 제작, 그 성능과 특징을 분석하여 발표한 바 있다. 기존 연구에서 제작된 Ag2S QDSC는 11 mA/cm2의 비교적 높은 광전류와 260 mV의 비교적 낮은 전압으로 인해 1.2%의 광전환효율 성능을 나타내는 것으로 보고되었다. 추후 연구로 진행된 본 결과에서는, 기존에 Single absorber로 사용된 Ag2S의 한계를 보완하기 위해 CdS를 도입하여 co-sensitization을 활용하였다. CdS는 약 2.3 eV의 밴드갭 에너지를 갖는 물질로, 1.1 eV의 밴드갭을 갖는 Ag2S에 비해 흡광 영역은 좁지만 그만큼 전자-정공 재결합을 억제할 수 있는 장점을 가지고 있다. 또한, 전도층으로 사용한 n-type 물질인 ZnO 나노선과의 밴드구조가 매우 적합하게 조화되어, ZnO/CdS/Ag2S 순서로 이종구조를 접합시켰을 때 세 물질의 Conduction band level과 Valence band level이 순차적으로 연결되는 cascade-shaped 밴드구조를 이루게 된다. 빛을 받아 Ag2S와 CdS에서 생성된 전자는 이 cascade 모양의 conduction band를 따라 순차적으로 ZnO로 잘 전달되게 되어, 효율 향상에 큰 도움을 주었다. 이런 장점들로 인해, CdS-Ag2S co-sensitized QDSC는 Ag2S QDSC에 비해 2배나 향상된 효율인 2.4%를 기록하였으며, 이는 IPCE spectrum 측정 등으로 근거가 뒷받침되었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.1
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• pp.1-9
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• 2005

A stoichiometric mixture of evaporating materials for AgGaS₂ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, AgGaS₂ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were 590℃ and 440℃, respectively. The temperature dependence of the energy band gap of the AgGaS₂ obtained from the absorption spectra was well described by the Varshni's relation, E/sub g/(T) = 2.7284 eV - (8.695×10/sup -4/ eV/K)T²/(T + 332 K). After the as-grown AgGaS₂ single crystal thin films was annealed in Ag-, S-, and Ga-atmospheres, the origin of point defects of AgGaS₂ single crystal thin films has been investigated by the photoluminescence (PL) at 10 K. The native defects of V/sub Ag/, V/sub s/, Ag/sub int/, and S/sub int/ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Ag-atmosphere converted AgGaS₂ single crystal thin films to an optical n-type. Also, we confirmed that Ga in AgGaS₂/GaAs crystal thin films did not form the native defects because Ga in AgGaS₂ single crystal thin films existed in the form of stable bonds.

• YAKHAK HOEJI
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• v.45 no.6
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• pp.708-714
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• 2001

Many studies have provided evidences that hepatitis B surface antigen (HBsAg) including preS region could be an ideal candidate for a new hepatitis B virus (HBV) vaccine with higher efficacy. We established CHO cell lines, IY-CHO-2 and IY-CHO-11 expressing high levels of HBsAg containing preS2 and S protein by stable transfection method. These cell lines expressed the correct size (about 1 kb in length) of HBsAg mRNA as expected. The purified protein from the culture supernatants of the clones showed the same sizes as those expressed in native hepatitis B virus (24 kDa, 27 kDa, 34 kDa and 36 kDa). Antibody productivity of CHO-derived HBsAg protein at lower dose challenge was higher than the protein containing S region alone expressed in yeast system. These results indicate that CHO-derived HBsAg protein containing preS2 and S region can be effectively used for a better immune response as a HBV vaccine.

• 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.

• Journal of Pharmaceutical Investigation
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• v.31 no.2
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• pp.101-106
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• 2001

Alginate-chitosan (anion-cationic polymeric complex) was prepared to control the release rate of silver sulfadiazine (AgSD). Na-alginate (2%) solution containing AgSD was gelled in $CaCl_2$ solution. The gel beads formed were immediately encapsulated with chitosan (CS). The gel matrix and membrane were then reinforced with chondroitin-6-sulfate (Ch6S). Release rate of AgSD from the gel matrix was investigated by placing alginate beads in the sac of cellulose membrane simmered in HEPES-buffer solution. The concentration of AgSD released was analyzed by UV at 264 nm. Incorporation capacity of AgSD in Ca-alginate gel was more than 90%. Alginate-Ch6S-CS could control the release rate of AgSD. The amount of AgSD release was dependent on the AgSD loading dose. Incorporation of tripolyphosphate (polyanionic crosslinker) onto the alginate-Ch6S-CS bead increased the release rate of AgSD. Collagen-coating had no influence on the AgSD release rate. Alginate-Ch6S-CS beads with a sufficiently high AgSD encapsulation were capable of controlling the release of the drug over 10 days. In summary, alginate-Ch6S-CS beads could be used as a sustained delivery for AgSD and provide local targeting with low silver toxicity and patient discomfort.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.101-102
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• 2006

A stoichiometric mixture of evaporating materials for $AgGaS_2$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films. $AgGaS_2$ mixed crystal was deposited on thoroughly etched semi-Insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $590^{\circ}C$ and $440^{\circ}C$, respectively. The temperature dependence of the energy band gap of the $AgGaS_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=2.7284 eV-(8.695{\times}10^{-4} eV/K)T^2/(T+332 K)$. After the as-grown $AgGaS_2$ single crystal thin films was annealed in Ag-, S-, and Ga-atmospheres, the origin of point defects of $AgGaS_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.483-488
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• 2012

We successfully decorated multi-wall carbon nanotubes (MWNTs) with silver by reacting Ag-NPs with thiolfunctionalized MWNT-SH. Ag alkylcarbamate complex was used as an Ag precursor. Uniform Ag-NPs (5-10 nm) were effectively prepared by microwaving within 60 s using 1-amino-4-methylpiperazine (AMP), which acts as a reaction medium, reducing agent, and stabilizer. The MWNTs were functionalized with 2-aminoethanethiol. Exploiting the chemical affinity between thiol and Ag-NPs, Ag-MWNT nanohybrids were obtained by spontaneous chemical adsorption of MWNT-SH to Ag through Ag-S bonds. The Ag-S-MWNTs were characterized by TGA, XRD, and TEM to confirm that Ag-NPs were uniformly decorated onto the MWNTs. The Ag-S-MWNTs were then employed as conducting filler in epoxy resin to fabricate electrically conducting polymer composites. The electrical properties of the composites were measured and compared with that containing MWNT-SH. The electrical conductivity of composites containing 0.4 wt % Ag-S-MWNT was four orders of magnitude higher than those containing same content of MWNT-SH, confirming Ag-S-MWNT as an effective conducting filler.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.92-96
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• 2002

A silver indium sulfide $(AgInS_{2})$ epilayer was grown by the hot wall epitaxy method, which has not been reported in the literature. The grown $AgInS_{2}$ epilayer has found to be a chalcopyrite structure and evaluated to be high quality crystal. From the photocurrent measurement in the temperature range from 30 K to 300 K, the two peaks of A and B were only observed, whereas the three peaks of A, B, and C were seen in the PC spectrum of 10 K. These peaks are ascribed to the band-ta-band transition. The valence band splitting of $AgInS_{2}$ was investigated by means of the photocurrent measurement. The crystal field splitting, $\Delta_{cr}$, and the spin orbit splitting, $\Delta_{so.}$ have been obtained to be 0.150 eV and 0.009 eV at 10 K, respectively. And, the energy band gap at room temperature has been determined to be 1.868 eV. Also, the temperature dependence of the energy band gap, $E_{g}(T)$, was determined.