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최상원,정관용,오남희,김은영,방정환,김정우,여문환 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5
The antibacterial effect amino acid-copper(Ⅱ) surfactant on fish pathogens was studied. Fish pathogens of Edwardsiella tarda, Vibrio anguillarum, Aeromonas hydrophila and Streptococcus sp. were selected, cultured in nutrient agar and adjusted at 2 × 10 exp (5)∼10 exp (6) CFU/㎖ in phosphate buffer saline before the addtion of amino acid-copper(Ⅱ) surfactant with different concentrations. All tested pathogens died within 1 hour with 1 ppm of amino acid-copper(Ⅱ) surfactant. In comparison with formalin and ET, amino acid-copper(Ⅱ) surfactnat was more effective in antibacterial capacity.
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High Precision FE Modeling for Predicting Inner Polygon Defect of Hot Rolled Seamless Steel Tubes
Yong-Zheng Jiang,Yong-Zheng Jiang,Xiao-Ping Zhang,Kuan-Fang He,Guan-Fu Bin 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.11
A high precision FE model is the key basis for cause analysis and overcoming of inner polygon defect of hot rolled seamless steel tubes. In this paper, the viscoelastic-plastic FEM is adopted in order to develop a high precision FE model for predicting the defect of inner polygon. Mechanical properties of tube material under rolling environment is obtained through five sets of high temperature compression tests, thus the viscoelastic-plastic constitutive equation of tube material is regressed and agrees with the tests results. Heat transfer boundary conditions, roll constant speed and contact friction boundary conditions are applied simultaneously on the FE model and thermo-mechanical coupled explicit algorithm is adopted for solution. The precision of the FE model is verified through industry experiments. Results shows the simulated inner wall shape is in good accordance with the experiment results, and the friction force, stress, strain and temperature distribution in the deformation zone are also discussed. It can be concluded that the viscoelastic-plastic FE model is of high precision and can be applied for better analysis of the hot rolling results.
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Kuan Peng,Yong-Bo Shao,Qing-li Wang,Yi-Fang Cao 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2
To study the hysteretic behavior of specimens of square concrete-fi lled CFRP-steel tube under diff erent infl uencing factors, a total of 12 specimens are designed, and the failure modes and P - Δ curves are investigated from experimental test. The simulation software ABAQUS is used to build the numerical model to study P - Δ curves and deformation mode of specimens. Based upon the tri-linear model, the restoring force model of square concrete-fi lled CFRP-steel tube is proposed, and the results of the tri-linear model are compared with those of the fi nite element model. The test results reveal that P - Δ curves of specimens are plump, and all specimens demonstrate excellent hysteretic behavior. The P - Δ curves, the skeleton curves and the deformation mode of specimens are reproduced by fi nite element model. The accuracy of the simulation results is verifi ed by comparing numerical results with experimental results. In terms of the restoring force model, a satisfactory agreement is achieved by comparing predicted results of tri-linear model with fi nite element simulations.
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Kim, Kwan,Choi, Jeong-Yong,Shin, Kuan Soo American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.9
<P>Hot electrons generated plasmonically from a Ag substrate can reduce 4-nitrobenzenethiol (4-NBT) to 4-aminobenzenethiol (4-ABT). In order to evaluate the effectiveness of hot electrons, we have carried out a surface-enhanced Raman scattering (SERS) study by forming a nanogap system composed of a planar Au substrate and an Ag-coated micrometer-sized silica bead, wherein 4-NBT was adsorbed first onto the Au substrate, and then Ag-coated silica beads, derivatized with 1-alkanethiols, were spread over the 4-NBT layer: the distance between 4-NBT and a nanostructured Ag substrate was varied by the chain length of alkanethiol molecules. Although the planar Au substrate itself was ineffective in the reduction of 4-NBT, hot electrons usable in the reduction of 4-NBT were generated from the Ag-coated silica beads. The hot electrons generated by 514.5 nm radiation were more effective in the reduction of 4-NBT to 4-ABT than those generated by 632.8 nm radiation, although the nanogap was more SERS-active with the excitation at 632.8 nm than at 514.5 nm. The photoreduction efficiency of hot electrons nonetheless decreased exponentially with the distance they traveled from the Ag surface: the reduction capability at a distance of 2 nm apart is about one-fourth of that in contact situations.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-9/acs.jpcc.5b00033/production/images/medium/jp-2015-00033x_0011.gif'></P>
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Kim, Kwan,Choi, Jeong-Yong,Lee, Hyang Bong,Shin, Kuan Soo American Chemical Society 2010 ACS APPLIED MATERIALS & INTERFACES Vol.2 No.7
<P>Silica-coated Ag nanostructures usable as magnetic nanoparticle-based Raman barcode materials were developed. Initially, 283 nm sized spherical magnetite particles composed of 13 nm sized superparamagnetic Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles were synthesized, and silver deposition was conducted using butylamine as the reductant of AgNO<SUB>3</SUB> in ethanol. The Ag-deposited Fe<SUB>3</SUB>O<SUB>4</SUB> (Fe<SUB>3</SUB>O<SUB>4</SUB>@Ag) particles are found to be efficient surface-enhanced Raman scattering (SERS) substrates with the enhancement factor at 632.8 nm excitation to be about 3 × 10<SUP>6</SUP>. After SERS markers such as benzenethiol, 4-mercaptotoluene, 4-aminobenzenethiol, and 4-nitrobenzenethiol were adsorbed onto the silver surface, poly(allylamine hydrochloride) (PAH) was coated onto them using the layer-by-layer deposition method such that a subsequent base-catalyzed silanization could readily form a 60 nm thick silica shell around the PAH layer by a biomimetic process. The cross-linked silica shells effectively prevented the SERS-marker molecules from being liberated from the surface of the Fe<SUB>3</SUB>O<SUB>4</SUB>@Ag particles. Although the gram magnetization decreased nearly to one-half of the initial value because of coating with silver and silica, the remaining magnetization was nonetheless strong enough for the silica-coated Fe<SUB>3</SUB>O<SUB>4</SUB>@Ag particles to be used as barcode materials operating via SERS.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2010/aamick.2010.2.issue-7/am1002074/production/images/medium/am-2010-002074_0004.gif'></P>
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Kim, Kwan,Choi, Jeong-Yong,Shin, Kuan Soo American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.21
<P>The origin of b<SUB>2</SUB>-type bands in the surface-enhanced Raman scattering (SERS) of 4-nitrobenzenethiol (4-NBT) and 4-aminobenzenethiol (4-ABT) has recently been debated because these bands are very similar to those attributed to a photoreaction product such as 4,4′-dimercaptoazobenzene (4,4′-DMAB). To resolve the debate, we obtained the SERS spectra of both 4-NBT and 4-ABT on Ag under ambient conditions and icy environments at 77 K. Under ambient conditions, the b<SUB>2</SUB>-type bands distinctly appeared in the SERS spectra of both 4-NBT and 4-ABT. In contrast, no b<SUB>2</SUB>-type peaks appeared in the SERS of 4-NBT in icy environments, suggesting that 4-NBT did not undergo a photoreaction. However, the SERS spectral pattern of 4-ABT was the same both at room temperature and in icy conditions. Because hot electrons are plasmonically generated from Ag even in icy environments, the lack of photoreaction of 4-NBT is likely a result of the small spaces between the ice crystals, rendering the N–O bond difficult to break. The situation of 4-ABT on Ag is identical to that of 4-NBT on Ag in the same conditions; therefore, the b<SUB>2</SUB>-type bands observed in icy conditions must be because of the 4-ABT, and not because of the production of 4,4′-DMAB or other photoreaction products. Regardless of temperature, hot electrons were more easily generated at lower excitation wavelengths, and the b<SUB>2</SUB>-type bands appeared more distinctly with a decrease in the excitation wavelength. From these observations, it can be surmised that the hot electrons, as well as the b<SUB>2</SUB>-type bands of 4-ABT, are associated with the charge-transfer chemical enhancement mechanism in SERS.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-21/jp5015115/production/images/medium/jp-2014-015115_0006.gif'></P>
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Kim, Kwan,Choi, Jeong-Yong,Shin, Dong-Ha,Lee, Hyang-Bong,Shin, Kuan-Soo Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.suppl8
A nanogap formed by a metal nanoparticle and a flat metal substrate is one kind of "hot site" for surface-enhanced Raman scattering (SERS). The characteristics of a typical nanogap formed by a planar Au and either an Au and Ag nanoparticle have been well studied using 4-aminobenzenethiol (4-ABT) as a probe. 4-ABT is, however, an unusual molecule in the sense that its SERS spectral feature is dependent not only on the kinds of SERS substrates but also on the measurement conditions; thus further characterization is required using other adsorbate molecules such as 1,4-phenylenediisocyanide (1,4-PDI). In fact, no Raman signal was observable when 1,4-PDI was selfassembled on a flat Au substrate, but a distinct spectrum was obtained when 60 nm-sized Au or Ag nanoparticles were adsorbed on the pendent -NC groups of 1,4-PDI. This is definitely due to the electromagnetic coupling between the localized surface plasmon of Au or Ag nanoparticle with the surface plasmon polariton of the planar Au substrate, allowing an intense electric field to be induced in the gap between them. A higher Raman signal was observed when Ag nanoparticles were attached to 1,4-PDI, irrespective of the excitation wavelength, and especially the highest Raman signal was measured at the 632.8 nm excitation (with the enhancement factor on the order of ${\sim}10^3$), followed by the excitation at 568 and 514.5 nm, in agreement with the finite-difference timedomain calculation. From a separate potential-dependent SERS study, the voltage applied to the planar Au appeared to be transmitted without loss to the Au or Ag nanoparticles, and from the study of the effect of volatile organics, the voltage transmission from Au or Ag nanoparticles to the planar Au also appeared as equally probable to that from the planar Au to the Au or Ag nanoparticles in a nanogap electrode. The response of the Au-Ag nanogap to the external stimuli was, however, not the same as that of the Au-Au nanogap.
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Kim, Kwan,Choi, Jeong-Yong,Shin, Kuan Soo Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
A few years ago, the plasmon-induced electronic coupling (PIEC) model was proposed in the literature to explain small changes in the surface-enhanced Raman scattering (SERS) in nanogap systems. If this model is correct, it will be very helpful in both basic and application fields. In light of this, we carefully reexamined its appropriateness. Poly(4-vinylpyridine) (P4VP) used in the earlier work was, however, never a proper layer, since most adsorbates not only adsorbed onto Ag nanoparticles sitting on P4VP but also penetrated into the P4VP layer deposited initially onto a flat Ag substrate, ultimately ending up in the SERS hot sites. Using 1,4-phenylenediisocyanide and 4-nitrophenol as the affixing layer and the foreign adsorbate, respectively, we could clearly reveal that the PIEC model is not suited for explaining the Raman signal in a nanogap system. Most of the Raman signal must have arisen from molecules situated at the gap center.
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