• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.537-538
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.299-300
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• 2007

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.285-294
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• 1994

Some supported gold catalysts were prepared by impregnation and coprecipitation methods. Effect of gold addition and active sloe formation were studied by investigating particle sizes of gold, amounts of oxygen adsorbed, adsorption properties of CO and NO, and reduction and oxidation properties, etc.. The gold particles of the catalyst by impregnation were irregular and very large as 30~100 nm, but those by coprecipitation were uniform and ultra-fine as about 4 nm. On $Au/Al_2O_3$ catalyst, the addition of gold to inactive $Al_2O_3$ caused the decomposition of $N_2O$, and CO was not irreversibly adsorbed while $O_2$ was atomically and irreversibly adsorbed. The adsorption sites of oxygen were attributed to the active sites which were restricted to the circumference of hemispherical gold particle-support interface rather than all atoms on the surface of gold particle. Also, CO was reversibly and irreversibly adsorbed on $Al_2O_3$ at low temperature, and the addition of gold weakened both reversible and irreversible adsorptions. The affinity for CO on $Au/Co_3O_4$ catalyst decreased conspicuously compared to $Co_3O_4$. The effect of gold addition did not appear in reduction step but did remarkably in reoxidation step; the added gold promoted the reoxidation of the reduced cobalt atoms.

• Korean Journal of Veterinary Research
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• v.49 no.4
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• pp.273-278
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• 2009

Neurofascin, one of the members of L1CAM, has been known to have some important roles during the development of nerve fibers. In order to investigate the role of neurofascin associated with the formation of Schmidt-Lantermann incisure in the sciatic nerve, the localization of neurofascin was studied with electron microscopy, immuno-fluorescence and immuno-electron microscopy. In the electron microscopy, the first formation of Schmidt-Lantermann incisure was checked at postnatal day 6 and the complete form of incisures traversing the whole myelin sheath began to be observed at postnatal day 8. In the immunofluorescence, neurofascin immunoreactive Schmidt-Lantermann incisures were first checked at postnatal day 6 and dramatically increased with aging by postnatal day 56. In the immunoelectron microscopy, neurofascin immunoreactive gold particles at the incisure forming sites were first observed at postnatal day 6 and the number of gold particles was increased as the animal was getting old by postnatal day 56. According to the present study, neurofascin is likely to have some relationships with Schmidt-Lantermann incisure formation.

• Tribology and Lubricants
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• v.33 no.6
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• pp.275-281
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• 2017

In this work, we have fabricated anodic aluminum oxide (AAO) with ordered nanoscale porosity through an anodization process. We deposited gold and nano-organic thin films on the porous AAO surface to protect its structure and reduce friction. We investigated the tribological characteristics of the porous AAO with respect to the protective surface coatings using tribometers. While investigating the frictional characteristics of the samples by applying normal forces of the order of micro-Newton, we observed that AAO without a protective coating exhibits the highest friction coefficient. In the presence of protective surface coatings, the friction coefficient decreases significantly. We applied normal forces of the order of milli-Newton during the tribotests to investigate the wear characteristics of AAO, and observed that AAO without protective surface coatings experiences severe damage due to the brittle nature of the oxide layer. We observed the presence of several pieces of fractured particles in the wear track; these fractured particles lead to an increase in the friction. However, by using surface coatings such as gold thin films and nano-organic thin films, we confirmed that the thin films with nanoscale thickness protect the AAO surface without exhibiting significant wear tracks and maintain a stable friction coefficient for the duration of the tribotests.

• The Korean Journal of Zoology
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• v.35 no.2
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• pp.149-160
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• 1992

Using the protein A-gold complex, the mvoabrillogenesis and actin localization of cultured myoblast were invastisated. In the superstructural changes of mvogenic cell during differentiation, pectoral myoblasts contained large nucleus and numerous ribosomes but no myofibrils during the first 24 hr of cultures. Mvoblast initiated to differentiate at 3-day of culture contained the primitive myofibrillar structure. At 96 hr of culture, the mvofibrillar structure showed reletively discernable Z band but pools defined A, H and M bands. The feature of sarcomeric structure showed more defined form at cultur 5 day. In the aspect of actin localization, actin wvas diffusely detected throughout the cytoplasm of myogenic cell and nucleus during the proliferating stage. At 72 hr of culture, with the appearantc oi primitive mvofibrils, gold particles were observed in surrounding of myofibrils but still presented in overall of cytoplasm, especially in the surface and lumen of endoplasmic reticulum. With the gradual increase of culture time, local distribution of actin was readily detected within cytoplasm. In the 5-day specimen of cultures, gold particles precisely indicate the sites of actin localifation within the sarcomere. These results indicate the time of onset of myofibrill appearance and the biosynthetic and incorporation pathway of actin molecules into sarcomeric structure during myofibrillogenesis. Thus, in the present study, the first mvoabrillar structure was detected at culture 3 day, and the initiation of assembly into a typical sarcmeric structure was observed at culture 5 day. It seems, however, that the course of events on myofibrillogenesis of cultured myoblasts can be changed with great dependence of culture conditions including the number and groluth rate of mononucleated mvoblasts after seeding although the fundamental process shows identical appearances.

• Applied Microscopy
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• v.28 no.2
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• pp.193-205
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• 1998

The Urechis unicinctus sperm and spermatogenic cells prepared from the testis are investigated to identify $\alpha-tubulin$ of axoneme microtubules using mouse monoclonal $anti-\alpha-tubulin$ as the first Ab and Gold(10nm) conjugated goat anti-mouse IgG as the Ab marker. The Ag-Ab reaction analyzed excellently the localization of $\alpha-tubulin$ and the gold particles incorporated with the proximal and distal centrioles, manchette microtubules, and flagellum. The gold particles can be also observed in the spermatogenic cells while the cells are still in sperm ball which is composed of a somatic cell and spermatogenic cells. The sperm ball is the functional unit of sperm production in U unicinctus testis. The spermatids are developed from the spermatogenic cells in the sperm ball and released into the testis cavity through a cortical cytoplasmic opening. The spermatid architectures are similar with the mature sperm of the testis cavity in aspects of shape of discoid acrosome, degree of nuclear condensation and ring type of mitochondrion. However, the distal centriole connecting with the flagella can be observed from the mature sperm while the both proximal and distal centrioles reveal only in the spermatids. The proximal centriole is directly connected with nuclear outer membrane during the stage of nuclear condensation and oriented perpendicularly to the distal centriole whose axis coinciding with the longitudinal axis of the spermatozoon. There are indications that the distal centriole is intimately associated with the polymerization of the flagellum. The manchette microtubules appear during spermatid development but the mature sperm have round head and no conspicuous middle piece.

• Parasites, Hosts and Diseases
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• v.29 no.1
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• pp.31-42
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• 1991

In order to observe the antigenic localization in the tissues of the young adult Paragenimus westermani, immunogold labeling method was applied using serum immunoglobulins (IgG) of the dog which infected with isolated metacercariae from Cambaroides similis. The sectioned worm tissue was embedded in Lowicryl HM 20 medium and stained with infected serum IgG and protein A gold complex(particle size; 12 nm) It was observed by electron microscopy at each tissues of the worm. The gold particles were not observed on the basal lamina of the tegument, interstitial matrix of the parenchyma, the muscle tissue and mitochondria of the tegument. The gold particles were specifically labeled in the secretory granules in the vitelline cells. They were predominantly labeling on the epithelial lamela and lumen of caecum. The above finding showed that antigenic materials in young adult worm tissue were specifically concentrated on the tegumental syncytium as well as cytoplasm of tegumental cells.

• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.1-9
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• 2024

Proton therapy is known for its superior treatment method due to Bragg peak. To enhance the therapeutic effects of protons, research has been conducted on distributing gold nanoparticles within tumors to increase the absorbed dose. While previous studies focused on handling gold nanoparticles at micrometer and nonometer scale, this study proposes a method to computationally estimate the effect of gold nanoparticles at the millimeter scale. The Geant4 toolkit was applied to computational modeling. Assuming a uniform distribution of water, similar to the human body, and gold nanoparticles, the concentration of gold nanoparticles was adjusted using density ratios. When the density ratio was 5%, the gain in absorbed energy due to gold nanoparticles was nearly twice that of the pure water phantom at the Bragg peak. As the density ratio increased, the gain in absorbed energy linearly increased. When gold nanoparticles were distributed in only one voxel at the Bragg peak, the energy of the protons affected only the neighboring voxels. However, in cases where gold nanoparticles were distributed over a wide area, the volume showing 95% of the maximum absorbed energy (9.46 keV) for the pure water phantom (9.95 keV) exhibited an improvement in absorbed energy over a region 16 times larger, and this region increased as the density ratio increased. Further research is needed to quantify the relationship between the density ratio of gold nanoparticles and the relative biological effect (RBE) in the millimeter scale.

• Tuberculosis and Respiratory Diseases
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• v.59 no.4
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• pp.397-405
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• 2005

Background : Laminin-1 is known to have regular functions in the development and course of differentiation of the lungs. The morphogenesis and distribution of laminin-1 still remains as a mystery and its distribution and changes in the molecular structure of laminin-1 in the pathogenesis of the lung still is a subject of great controversy. In this study, experiments were done to delineate the distribution and changes in the amount of laminin-1 after inducing inflammation of the lungs by exposing experimental animals to CS gas and especially, to find compositions of laminin-1 within type II pneumocytes. Materials and Methods : The experimental subjects of study were newborn rats and the extracted tissue from the experimental rats were viewed under light microscope and electron microscope after the sections were treated with immunohistochemical methods and immunogold reaction methods using bounded gold particles. Results : 1) Lymphocytes and mononuclear phagocytes invaded the alveolar septa in the 2 day group rats after CS gas exposure and intense interstitial inflammation was seen in the 3 day group. 2) Laminin immunoreactions decreased to a moderate degree in the 2 and 3 day group rats after CS gas exposure and strong laminin immunoreactions were seen again in the 5 and 7 day group rats. 3) Gold particles in basal lamina of the lung blood-air barrier decreased and in the type I pneumocytes decreased in the 2 and 3 day group rats after CS gas exposure. 4) Gold particles were seen only on the surface of the cell membranes of type II pneumocytes of the 1 and 2 day group rats after CS gas exposure. 5) Few gold particles around the lamellar bodies and cytoplasm of type II pneumocytes in the control rat group and at 12 hours after CS gas exposure. Gold particles are seen only on the surface of type II pneumocytes of the 1 and 2 day group rats after CS gas exposure and are evenly distributed in small amounts in the cells of the 3 day group after CS gas exposure. Conclusion : CS gas exposure in the rats caused inflammation of lung alveolar septa and also induced a decrease in laminin-1 in basal lamina and loss of laminin-1 in the cytoplasm of type II pneumonocytes. As the inflammatory cells disappeared, an increase in the distribution of laminin-1 occurred. This reflects tissue regeneration functions of laminin-1 in the pneumocytes of rats and the distribution of laminin-1 in type II pneumocytes can be seen through the electron microscope using immunogold methods.