• 한국전기전자재료학회논문지
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• 제31권1호
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• pp.34-39
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• 2018

In this study, e-beam equipment was used to form silver nanoparticles on thin films of $TiO_2$ to increase the efficiency of dye-sensitized solar cells and improve the annealing process. $TiO_2$ thin films with nanoparticle photoelectrodes were fabricated in individual units for use in dye-sensitized solar cells. The characteristics of dye-sensitized solar cells were compared to those of the prepared $TiO_2$ photoelectrode with and without nanoparticles. The dye-sensitized solar cells with silver nanoparticles showed a significant increase in the electric current density compared with the pure $TiO_2$ dye-sensitized solar cell and improved the solar conversion efficiency to 27.89%. The increased density of electric current increased the extent of light absorption of the dye owing to the plasmon resonance of the nanoparticles at the local surfaces. This phenomenon led to increased light scattering, which in turn increased the current density of the dye-sensitized solar cells and improved the solar conversion efficiency.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1279-1282
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• 2018

This paper reports the deposition of a metal line using a multilayer stack and laser-induced forward transfer (LIFT) using a low cost continuous wave blue laser with a wavelength of 450 nm. The donor structure was composed of a light-to-heat (LTH) layer, a release layer, and a transfer layer in series. Amorphous silicon as the LTH layer absorbs photon energy and converts it to heat. A release layer was melted so that a silver transfer layer would be transferred to the receiver substrate. The transferred silver layer showed reasonable physical and electrical characteristics. A low cost fine linewidth metal layer could be achieved using this modified LIFT technique and blue laser.

• 한국임상수의학회지
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• 제28권6호
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• pp.576-580
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• 2011

은 이온(silver ion)은 동물세포에 낮은 독성을 가지면서도 다양한 종류의 세균들에 대해 강력한 항균력을 가지고 있다. 본 연구에서는 젖소 유방염 원인균들에 대한 은 이온의 항균효과를 전자현미경(TEM)을 통해 조사하였다. 본 실험에 사용된 균주는, 젖소 유방염의 주요 원인균인 Escherichia coli 와 Staphylococcus aureus를 사용하였다. 유방염 원인균에 대한 은 이온의 항균효과를 관찰하기 위해 50 ${\mu}g/mL$의 은 이온을 2시간 동안 세균에 노출시킨 후 전자현미경(Energy-Filtering Transmission Electron Microscopy, EFTEM) 을 이용하여 은 이온에 의한 세균의 형태 변화를 확인하였다. 은 이온 처리 후 전자현미경 촬영 결과 E. coli 와 S. aureus의 세포막이 변형되고, 세포 외부에 침착된 은 이온과, electron-light 모습으로 세포내 분산된 은 이온을 관찰 할 수 있었으며, 결과적으로 E. coli 와 S. aureus의 세포막이 파괴되어, 세포내용물이 외부에 누출됨으로써 세균이 사멸되는 것을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.791-794
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• 2005

A visible photochemistry of maleic to fumaric acid adsorbed on silver nanoparticle surfaces was investigated as probed by SERS using a simple flow method. Photoisomerization of maleic to fumaric acid was consecutively observed in the condition of various flow rates, which varied the exposure time of laser beam. The sequential SERS spectra of maleic acid indicated that the photochemical isomerization and desorption took place simultaneously on silver nanoparticle surfaces as a function of laser fluency and wavelength. For 530.9nm laser line excitation, the rate constant coefficients were obtained with a = 5.9 $sec^{-1}$ mW for isomerization and b = 13.9 $sec^{-1}$ mW for desorption, which $k_1\;=\;aI^n\;and\;k_2\;=\;bI^m$. Both reactions were one photon process (n = 1, m = 1) of a visible light and relatively fast process whose decay time was in the range of milli-second for 50 mW laser power. The rate of photochemical reaction increased on going toward the blue and photodesorption was a dominant process. A simple flow method used in this study was very useful to study a relatively fast photochemical reaction of molecules adsorbed on silver nanoparticle surfaces.

• 한국의류학회지
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• 제14권4호
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• pp.281-291
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• 1990

Experiment I and II had done to develop the solar heat proof hat for field work in the summer. In the experiment I physical characteristics of several fabrics was tested to determine which one Is proper to make the solar heat proof hat. On the base of above results in the experiment II three improved solar heat proof hat was deviced and tested solar heat proof effect and compared the existing summer working hat by wearing trials in the environmental chamber. The results obtained were as follows. 1. In the view of the physical characteristics of six fabrics (Blue T/C, White poplin, Vapor transfer silver coating nylon taffeta, No vapor trans(or silver coating nylon taffeta, Aluminum coating T/C, Microporous fabric), the light color T/C and no vapor transfer silver coating nylon ta(feta is proper to make improved solar heat proof working hat. 2. Three improved hats that are made of white T/C, grey T/C and no vapor transfer silver coating nylon taffeta have more solar heat proof effect than the existing summer working hat. 3. Among the three improved hats, the improved hat that is made of no vapor transfer silver coating nylon taffeta is most effective to proof the solar heat.

• Mycobiology
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• 제46권1호
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• pp.47-51
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• 2018

In the present study, the characterization and properties of silver nanoparticles from Yucca shilerifera leaf extract (AgNPs) were investigated using UV-visible spectroscopic techniques, zeta potential, and dynamic light scattering. The UV-visible spectroscopic analysis showed the absorbance peaked at 460 nm, which indicated the synthesis of silver nanoparticles. The experimental results showed silver nanoparticles had Z-average diameter of 729 nm with lower stability (195.1 mV). Additionally, our dates revealed that AgNPs showed broad spectrum antagonism ($p{\leq}.05$) against Fusarium solani (83.05%) and Macrophomina phaseolina (67.05%) when compared to the control after nine days of incubation. Finally, AgNPs from leaf extracts of Y. shilerifera may be used as an agent of biocontrol of microorganism of importance. However, further studies will be needed to fully understand the agronanotechnological potentialities of AgNPs from Yucca schidigera.

• Advances in nano research
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• 제5권4호
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• pp.373-392
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• 2017

Silver nanoparticles (AgNPs) were successfully synthesized through a simple green route using the Nelumbo nucifera leaf, stem and flower extracts. These nanoparticles showed characteristic UV-Vis absorption peaks between 410-450 nm which arises due to the plasmon resonance of silver nanoparticles. The Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of amides and which acted as the stabilizing agent. X-ray diffraction spectrum of the nanoparticles confirmed the Face centered cubic (FCC) structure of the formed AgNPs. Dynamic light scattering technique was used to measure hydrodynamic diameter (68.6 nm to 88.1 nm) and zeta potential (-55.4 mV, -57.9 mV and 98.9 mV) of prepared AgNPs. The scanning electron micrographs of dislodged nanoparticles in aqueous solution showed the production of reasonably monodispersed silver nanoparticles (1-100 nm). The antimicrobial activity of prepared AgNPs was evaluated against fungi, Gram-positive and Gram-negative bacteria using disc diffusion method. Anti-corrosion studies were carried out using coupon method (mild steel and iron) and dye degradation studies were carried out by assessing photo-catalytic activity of Nelumbo nucifera extracts mediated AgNPs.

• 한국해양환경ㆍ에너지학회지
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• 제12권4호
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• pp.302-306
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• 2009

이 연구에 사용된 9종류의 나노입자는 직경 100 nm 이하의 크기를 가진 입자로, 알테미아 cyst가 nauplius로 부화되는 과정에서 어떠한 영향을 미치는지 살펴보았다. 24시간 경과 후 나노입자를 첨가하지 않은 대조구에서는 82%가 nauplius로 부화하였다. 20 mg/L 농도에서는 AGZ020, Nano silver, P-25, Sb, 및 SnO 나노입자가 각각 18%, 20%, 13%, 50% 및 0%의 부화율을 보여 유해성이 큰 것으로 나타났으나, Ag-$TiO_2$, In, Sn, 및 Zn 나노입자에서는 각각 75%, 60%, 73% 및 73%로 대조구에 비해 유해성을 가졌지만, AGZ020, Nano silver, P-25, Sb, 및 SnO 나노입자에 비해 상대적으로 미약한 것으로 나타났다. 이는 나노입자가 가지고 있는 성분에 따라서 차이가 났다. AGZ020, Nano silver 및 P-25 나노입자는 은(Ag)이 2% 함유되어 항균제로서 널리 사용되어지고 있으며, 산소를 결합시킨 SnO 나노입자는 광촉매제로 사용되고 있다. 이들 나노입자들은 현재 가전, 기능성 화장품, 항균제 및 광촉매제 등 사용이 일반화되어 수중환경으로 유입될 가능성이 높아지고 있다. 이에 따라 수중생태계에 점차 영향을 줄 가능성이 높기에, 나노입자가 가지는 잠재적 위험성을 지속적으로 연구해야 할 것이다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2008년도 춘계학술발표회
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• pp.137-141
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• 2008

이 연구에 사용된 9종류의 나노입자는 직경 100nm 이하의 크기를 가진 입자로, 알테미아 cyst가 nauplius로 부화되는 과정에서 어떠한 영향을 미치는지 살펴보았다. 24시간 경과 후 나노입자를 첨가하지 않은 대조구에서는 82%가 nauplius의 부화하였다. 20mg/L 농도에서는 AGZ020, Nano silver, P-25, Sb, 및 SnO 나노입자가 각각 18%, 20%, 13%, 50% 및 0%의 부화율을 보여 유해성이 큰 것으로 나타났으나, Ag-$TiO_2$, In, Sn, 및 Zn 나노입자에서는 각각 75%, 60%, 73% 및 73%로 대조구에 비해 유해성을 가졌지만, AGZ020, Nano silver, P-25, Sb, 및 SnO 나노입자에 비해 상대적으로 미약한 것으로 나타났다. 이는 나노입자가 가지고 있는 성분에 따라서 차이가 났다. AGZ020, Nano silver 및 P-25 나노입자는 은(Ag)이 2% 함유되어 항균제로서 널리 사용되어지고 있으며, 산소를 결합시킨 SnO 나노입자는 광촉매제로 사용되고 있다. 이들 나노입자들은 현재 가전, 기능성 화장품, 항균제 및 광촉매제 등 사용이 일반화되어 수중환경으로 유입될 가능성이 높아지고 있다. 이에 따라 수중생태계에 전파 영향을 준 가능성이 높기에, 나노입자가 가지는 잠재적 위험성을 지속적으로 연구해야 할 것이다.

• Restorative Dentistry and Endodontics
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• 제37권1호
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• pp.41-49
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• 2012

Objectives: The internal adaptation of composite restorations with or without resin modified glass ionomer cement (RMGIC) was analyzed non-destructively using Microcomputed tomography (micro-CT). Materials and Methods: Thirty intact human teeth were used. The specimens were divided into 3 groups. In the control group, the cavities were etched with 10% phosphoric acid for 15 sec. Composite resin was filled into the cavity without adhesive. In group 1, light cured glass ionomer cement (GIC, Fuji II LC, GC) was applied as a base. The cavities were then etched, bonded, light cured and filled with composites. In group 2, the cavities were then etched, bonded, light cured and filled with composites without base application. They were immersed in a 25% silver nitrate solution. Micro-CT was performed before and after mechanical loading. One-way ANOVA with Duncan analysis was used to compare the internal adaptation between the groups before or after loading. A paired t-test was used to compare internal adaptation before and after mechanical loading. All statistical inferences were made within the 95% confidence interval. Results: The silver nitrate solution successfully penetrated into the dentinal tubules from the pulp spaces, and infiltrated into the gap between restoration and pulpal floor. Group 2 showed a lower adaptation than the control group and group 1 (p < 0.05). There was no significant difference between the control group and group 1. For all groups, there was a significant difference between before and after mechanical loading (p < 0.05). Conclusions: The internal adaptation before and after loading was better when composites were bonded to tooth using adhesive than composites based with RMGIC.