• Advances in nano research
• /
• v.5 no.4
• /
• pp.359-372
• /
• 2017

Metallic copper nanoparticles were synthesised by reduction of copper ions in aqueous solution, and metal-metal bonding by using the nanoparticles was studied. A colloid solution of metallic copper nanoparticles was prepared by mixing an aqueous solution of $CuCl_2$ (0.01 M) and an aqueous solution of hydrazine (reductant) (0.2-1.0 M) in the presence of 0.0005 M of citric acid and 0.005 M of n-hexadecyltrimethylammonium bromide (stabilizers) at reduction temperature of $30-80^{\circ}C$. Copper-particle size varied (in the range of ca. 80-165 nm) with varying hydrazine concentration and reduction temperature. These dependences of particle size are explained by changes in number of metallic-copper-particle nuclei (determined by reduction rate) and changes in collision frequency of particles (based on movement of particles in accordance with temperature). The main component in the nanoparticles is metallic copper, and the metallic-copper particles are polycrystalline. Metallic-copper discs were successfully bonded by annealing at $400^{\circ}C$ and pressure of 1.2 MPa for 5 min in hydrogen gas with the help of the metalli-ccopper particles. Shear strength of the bonded copper discs was then measured. Dependences of shear strength on hydrazine concentration and reduction temperature were explained in terms of progress state of reduction, amount of impurity and particle size. Highest shear strength of 40.0 MPa was recorded for a colloid solution prepared at hydrazine concentration of 0.8 M and reduction temperature of $50^{\circ}C$.

• Current Optics and Photonics
• /
• v.7 no.6
• /
• pp.608-637
• /
• 2023

The initial motivation in colloid science and engineering was driven by the fact that colloids can serve as excellent models to study atomic and molecular behavior at the mesoscale or microscale. The thermal behaviors of actual atoms and molecules are similar to those of colloids at the mesoscale or microscale, with the primary distinction being the slower dynamics of the latter. While atoms and molecules are challenging to observe directly in situ, colloidal motions can be easily monitored in situ using simple and versatile optical microscopic imaging. This foundational approach in colloid research persisted until the 1980s, and began to be extensively implemented in optics and photonics research in the 1990s. This shift in research direction was brought by an interplay of several factors. In 1987, Yablonovitch and John modernized the concept of photonic crystals (initially conceptualized by Lord Rayleigh in 1887). Around this time, mesoscale dielectric colloids, which were predominantly in a suspended state, began to be self-assembled into three-dimensional (3D) crystals. For photonic crystals operating at optical frequencies (visible to near-infrared), mesoscale crystal units are needed. At that time, no manufacturing process could achieve this, except through colloidal self-assembly. This convergence of the thirst for advances in optics and photonics and the interest in the expanding field of colloids led to a significant shift in the research paradigm of colloids. Initially limited to polymers and ceramics, colloidal elements subsequently expanded to include semiconductors, metals, and DNA after the year 2000. As a result, the application of colloids extended beyond dielectric-based photonic crystals to encompass plasmonics, metamaterials, and metasurfaces, shaping the present field of colloidal optics and photonics. In this review we aim to introduce the research trajectory of colloidal optics and photonics over the past three decades; To elucidate the utility of colloids in photonic crystals, plasmonics, and metamaterials; And to present the challenges that must be overcome and potential research prospects for the future.

• The Korean Journal of Nuclear Medicine
• /
• v.5 no.1
• /
• pp.49-64
• /
• 1971

The radioactive $^{131}I$-rose bengal serial scintiphotography was performed in 62 patients with the hepatobiliary diseases and in 20 normal subjects. This approach permitted visualization of the hepatic uptake of $^{131}I$-rose bengal from the circulation and its excretion into the biliary trees and the intestines. In some of these patients, gallbladder function was examined, using eggs as a gallbladder constrictor. The time of maximum hepatic uptake was well correlated to the conventional biochemical liver function tests. In addition to $^{131}I$-rose bengal scintiphotography, $^{198}Au$-colloid scintiphotography was also performed to make comparison of these two tests. The results obtained were as follows: 1. In normal subjects, the maximum hepatic uptake of $^{131}I$-rose bengal occurred at $23{\pm}2.9$ minutes, the initial hepatic excretion at $34{\pm}5.1$ minutes, the visualization of the gallbladder at $29{\pm}5.7$ minutes and the intestinal visualization at $54{\pm}25.8$ minutes. The radioactivity in the gallbladder decreased to $10.7{\pm}5.0%$ one hour after the ingestion of eggs. 2. In the patients with cirrhosis of the liver, there was a delayed and decreased hepatic uptake. The maximun hepatic upake occurred at $43{\pm}12.9$ minutes. The differences in the results of uptake between the cirrhotic and the normal group were statistically significant. The initial hepatic excretion occurred at $60{\pm}18.5$ minutes and had tendency of delaying compared with the normal controls. The gallbladder was visualized in 13 of 16 cases (81%) and its visualization occurred at $49{\pm}14.6$ minutes with a tendency to be delayed compared with the normal controls. The intestinal visualization occurred at $63{\pm}15.8$ minutes and its delaying tendency was somewhat more prominent. 3. In patients with hepatitis, the maximum hepatic uptake occurred at $59{\pm}21.4$ minutes and was significantly delayed. The initial hepatic excretion occurred at $82{\pm}34.3$ minutes and the results revealed a delaying tendency. The gallbladder was visualized in 15 of 20 cases (75%) at $57{\pm}18.7$ minutes, which was significantly delayed. The Intestinal visualization was noted in all cases with marked delay. 4. In patients with obstructive jaundice, the maximum hepatic uptake was noted at $83{\pm}14.7$ minutes, showing the most significant delay. The hepatic excretion into biliary trees and intestines was not entirely noted in all cases except the only one case with gallbladder visualization. 5. In patients with cholelithiasis, the maximum hepatic upake and the initial hepatic excretion were slightly delayed with mean times of $39{\pm}11.2\;and\;48{\pm}17.1$ minutes respectively. The visualization of the gallbladder was demonstrated in 10 of 17 cases (59%) and occurred at $52{\pm}25.6$ minutes with a slight delay. The intestinal visualization occurred at $67{\pm}47.7$ minutes and was slightly delayed. $^{131}I$-rose bengal in the gallbladder remained high, $49.3{\pm}21.3%$, which suggested quantitatively decreased power of gallbladder constriction. 6. The time of the maximum hepetic uptake was correlated well to BSP retention and serum alkaline phosphatase ativity. However, the maximum hepatic uptake had no definite correlation with serum albumin, serum globulin, TTT, serum cholesterol, SGPT or SGOT. 7. In the diagnosis of the hepatobiliary diseases with jaundice, $^{131}I$-rose bengel serial scintiphotography has proved to be more useful than $^{198}Au$-colloid scintiphotography. With these results, it could be justified that $^{131}I$-rose bengal scintiphotography is an excellent diagnostic aid for dynamic hepatobiliary function studies in the clinical practice.

• Nuclear Medicine and Molecular Imaging
• /
• v.43 no.1
• /
• pp.55-59
• /
• 2009

Purpose: Lymphoscintigraphy and sentinel node biopsy are used in detection of axillary lymph node metastasis in breast cancer patients, but standardized technique is not established. We compared the results of the injection the morning of surgery (1 day protocol) with the subareolar injection the day before surgery (2 day protocol) with the subareolar injection in patients with breast cancer having lymphoscintigraphy and sentinel node biopsy. Materials and Methods: This study included 349 patients who underwent the breast cancer operation during 2001-2004. One hundred seventy one patients (1 day protocol, 1 hour) was injected 0.8ml of Tc-99m Tin-Colloid (37 MBq) by subareolar injection on the morning of surgery. One hundred seventy eight patients (2 day protocol, 16 hour) was injected 0.8 ml of T c-99m Tin-Colloid (185 MBq) on the afternoon before surgery. Lymphoscintigraphy was performed in sitting position and sentinel node localization was performed by hand-held gamma probe during operation. Result: In the 1 day protocol, 153 cases (89.5%) of the sentinel node were localized by lymphoscintigraphy and 150 cases (87.7%) were localized by gamma probe. In the 2 day protocol, 159 cases (89.3%) were localized by lymphoscintigraphy and 154 cases (86.5%) were localized by gamma probe. There was no significant difference in localization of sentinel node between the 1 day and the 2 day protocol by lymphoscintigraphy and gamma probe (p>0.05, p>0.05). Conclusion: There was no difference the result of localization of sentinel node with subareolar injection between the 1 day and the 2 day protocol in breast cancer patients. Because the 2 day protocol allows the enough time of performing lymphoscintigraphy, it is more useful in localization of sentinel node in breast cancer patients.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1997.06a
• /
• pp.41-44
• /
• 1997

Dispersion and flocculation behaviors of clay-ash powders in a slurry state were examined, and we have systematically investigated the effects of colloid/interfaces variables on slip properties and the rheological behavior of ash-clay slurry. Ash-clay slurries have been characterized on the basis of the time dependent rheology which was done out by the gel-curve test. Gel-curve for the coagulated slip shows interesting rheological behavior which was caused by the formation of the new network structure and the readsoption of the polysilicon hydroxo species on the particle surfaces.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.4
• /
• pp.332-336
• /
• 2006

In this study, melamine-formaldehyde microcapsules were prepared via in situ polymerization using peppermint oil as a core material, melamine-formaldehyde as the wall material, Tween 20 as the emulsifier, and poly (vinyl alcohol) as a protective colloid. The melamine-formaldehyde microcapsules prepared in this study were then evaluated with regard to their structures, thermal properties, particle size distributions, morphologies, and release behaviors.

• Textile Coloration and Finishing
• /
• v.22 no.2
• /
• pp.163-172
• /
• 2010

In order to investigate the changes in mechanical properties of sanitary nonwoven fabrics actually used as a top sheet, the fabric was treated with a mixture of chitosan and nanosilver colloidal solution in accordance with the prescribed ratio. The former is a natural polymer with excellent biocompatibility and the latter can give an additional performance while compensating the weaknesses of chitosan of deteriorating adherence efficiency. It was shown that the bending and shearing characteristics of the chitosan/nanosilver treated fabrics decreased, which helped to make it softer, smoother and more flexible. The shape stability and drapability of the treated fabrics improved. As KES-FB system evaluation showed that Koshi was deduced, and both Numeri and Fukurami were increased. Thereby, the chitosan/nanosilver treated fabrics were smoother to provide elasticity. In the change of hand value compared to chitosan only treatment, a better THV was shown in the fabrics treated with chitosan/nanosilver mixed solution than the fabric treated with chitosan alone.

• The Korean Journal of Cytopathology
• /
• v.14 no.1
• /
• pp.22-26
• /
• 2003

Cystic hypersecretory carcinoma of the breast is a rare variant of ductal carcinoma of breast, first described in 1984 by Rosen and Scott. Histologically, it is characterized by the formation of dilated ducts and cysts containing an eosinophilic secretory product resembling thyroid colloid. Cytologic findings show a few clusters of atypical ductal epithelial cells in amorphous proteinaceous material with clacking artifact. Differential diagnosis include mucinous carcinoma and benign mucocele-like tumor. We present two cases of fine needle aspiration cytology of cystic hypersecretory intraductal carcinoma of the breast with a review of the literature.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.560-563
• /
• 2008

A modified polyol process is developed to enhance Pt loading during the preparation of Pt/C catalysts. With the help of the zeta potential, the effect of pH on the electrostatic forces between the support and the Pt colloid is investigated. It is shown experimentally that the surface charge on the carbon support becomes more electropositive when the solution pH is changed from alkaline to acidic. However, this change does not affect the electronegative surface charge of Pt colloids already attained and stabilized by glycolate anions. This new behavior caused by the change in the solution pH accounts for the enhanced yield of the process and does not affect the Pt particle size. All our experimental results reveal that this simple modification is a cost effective method for the synthesis of highly Pt loaded Pt/C catalysts for fuel cells.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.1398-1402
• /
• 2005

Riverbank filtration is a natural process using alluvial aquifers to remove contaminants and pathogens in river water for the production of drinking water. In riverbank filtration, the understanding of contaminant transport is an important task for the production of high quality drinking water. This study investigates the transport behavior of hydrophobic organic contaminants when colloids (dissolved organic matter and bacteria) are present in the aquifer. A mathematical model for the transport of contaminants is developed and solved numerically for various situations. Results show that in the riverbank filtration the presence of DOM and bacteria enhances the mobility of contaminant significantly. Sensitivity analysis indicates that the distribution of the total aqueous Phase contaminant is significantly affected by distribution coefficients which account for affinity of solid or colloidal Phase to contaminant.