• The Korean Journal of Zoology
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• v.30 no.1
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• pp.53-70
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• 1987

The morphological study on the parenchymal cells in the adult planaria performed to observe their cytochemical and ultrastructural characteristics. The results are as follows. Nine types of cells are found in parenchyma. 1. Free parenchymal cell: These cells contain several chromatoid bodies around the nucleus. Heterochromatins are evenly dispersed in large nucleus. These cells are abundant in free ribosomes. 2. Fixed parenchymal cells: These cells have well-developed granular endoplasmic reticulum, mitochondria and Golgi complex but they contain the cytosols exhibiting electron-lucencies. 3. Rhabdite-forming cells: These cells contain the electron-dense rhabdite granules of up to about 0.3 x 0.9 $\mu$m in size. Rhabdite-forming cells have well-developed cell organelles, granular endolplasmic reticulum, mitochondria and Golgy complex. 4. A-type of basophilic granule cells: These cells contain irregularly-shaped granules exhibiting alcianophilia. These granules surrounded by a limited membrane, approximately 1.4 x 0.7 $\mu$m in size, are accumulated in the cytoplasm. 5. C-type of basophilic granule cells: These cells contain electron-dense granules of less than 0.2 $\mu$m in size, which exhibit PAS- positive reaction. This type of granule is also found in the muscle layer of parenchyma. 6. D-type of basophilic granule cells: This type of granule cell occurs only in the parenchyma around reproductive organ. The granules have cytochemical characteristics that they exhibit strongly positive reaction with PAS and weakly eosinophilic property. These electron-dense granules, which are 0.2 to 0.6 $\mu$m in length, have oval shapes. 7. E-type of basophilic granule cells: These cells are found only in the parenchyma around re productive organ. The granules contained in a small number in the cell, exhibit PAS-positive reaction and have an average size of 0. 2pm. 8. Eosinophilic granule cells: These cells contain a large number of eosinophilic granules which have relatively diverse sizes from 0.3 x 0.2 to 0.8 x 0.4 $\mu$m. Most of granules are round or irregularly-shaped and highly electrondense. These cells have an array of well-developed granular endoplasmic reticulum of which cisternae are distened. 9. Transparent granule cells contain electron-lucent granules which exhibit negative reactions with three kinds of cytochemical methods used in this experiment.

• Polymer(Korea)
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• v.38 no.4
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• pp.550-556
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• 2014

Recently, the peptide(or protein)-polymer hybrid materials (PPs) were sought in many research areas as potential building blocks for assembling nanostructures in selective solvents. In PPs, the facile routes of preparing well-defined peptide-polymer bio-conjugates and their specific activities in various applications are important issues. Our strategy to prepare the peptide-polymer hybrid materials was to combine atom transfer radical polymerization (ATRP) method with solid phase peptide synthesis. The standard solid phase peptide synthesis method was employed to prepare the PYGK (proline-tyrosine-glycine-lysine) peptide. PYGK is an analogue peptide, PFGK (proline-phenylalanine-glycine-lysine), which interacted with plasminogen in fibrinolysis. The peptide and the peptide-initiator were characterized with MALDI-TOF mass spectrometry and $^1H$ NMR spectrometer. The peptide-polymer, pSt-PYGK was characterized by GPC, IR, $^1H$ NMR spectrometer and TLC. Spherical micellar aggregates were determined by TEM and SEM. Current synthesis methodology suggested opportunities to create the well-defined peptide-polymer hybrid materials with specific binding activity.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.84-88
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• 2009

Al doped $LiMn_2O_4$ cathode powders with fine size were synthesized by an ultrasonic spray pyrolysis method from the spray solution with citric acid and ethylene glycol. The as-prepared powders with spherical shape, porous structure and micron size turned into $LiMn_{11/6}Al_{1/6}O_4$ powders with micron size and regular morphology after post-treatment above $800^{\circ}C$. The $LiMn_{11/6}Al_{1/6}O_4$ powders had low initial discharge capacity of 94 mAh/g at a post-treatment temperature of $700^{\circ}C$. As the post-temperature increased from $750^{\circ}C$ to $1,000^{\circ}C$, the initial discharge capacities of the $LiMn_{11/6}Al_{1/6}O_4$ powders changed from 103 to 117 mAh/g. The $LiMn_{11/6}Al_{1/6}O_4$ powders had the maximum discharge capacity at a post-treatment temperature of $750^{\circ}C$. However, the $LiMn_{11/6}Al_{1/6}O_4$ powders post-treated at a temperature of $900^{\circ}C$ had the good cycle properties. The discharge capacities of the $LiMn_{11/6}Al_{1/6}O_4$ powders dropped from 107 to 100 mAh/g (93% capacity retention) by the 70th cycle at a current density of 0.1 C.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.1939-1946
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• 2012

High performance steel for bridges requires higher performance in tensile and yield strength, toughness, weldability, etc. The purpose of this study is to investigate the weldability of HSB 600 steel. The effects of heat input (1.4~3.2kJ/mm) and postweld heat treatment (PWHT, $600^{\circ}C$, 40hr.) on the TMCP HSB600 steel weldments made by GMAW process were investigated. The tensile strength and hardness of as-welded specimens decreased with increasing heat input. Charpy V-notch impact energy did not show any significant difference by postweld heat treatment. The fine-grained acicular ferrite was mainly formed in the 2.1kJ/mm of heat input while polygonal and side plate ferrites were dominated in the high inputs. Meanwhile, tensile strength and hardness of PWHT weldments decreased due to the coarsening and globularization of ferrite microstructure and reduction of residual stresses with increasing heat inputs. However, there was no significant difference in the impact energy absorption.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.86-91
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• 2004

$LiCoO_2$ cathode powders with round particle shaped and nano grain sized of 70-300nm were synthesized by a mechanochemical method. The surface of Li-Co precursor prepared by freeze drying method was modified by $K_2SO_4$ coating and ball milling was used for the coating process. The precursor was crystallized to high temperature form of $LiCoO_2$ at $800^{\circ}C$ and the grain growth was inhibited by the $K_2SO_4$ coating effect. The $K_2SO_4$ coating was not decomposed at $800^{\circ}C$ and prevented the contact in the Li-Co precursor particles. The nano-sized $LiCoO_2$ powder had tetragonal phase and it affected the Li diffusion through the surface of particles. It means that the anode materials for hight performance battery should be satisfied not only small particle size but phase contol on the surface of particles. In this study, the powder characteristics and rate capabilities were compared with a commercial powder and the nano-sized $LiCoO_2$ powder fabricated by the mechanochemical method. And the crucial factor which affects on battery performance was also examined.

• Polymer(Korea)
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• v.30 no.6
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• pp.512-518
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• 2006

A biodegradable polymer poly((R) -3-hydroxybutyric acid) (PHB) was conjugated with a hydrophilic polymer poly(ethylene glycol) (PEG) by the ttansesterification reaction to form the amphiphilic block copolymer. PHB with low molecular weight ($3000{\sim}30000$) was appropriated for the drug delivery materials. High molecular weight PHB was hydrolyzed by an acid-catalyst to produce the low molecular weight one. Amphiphilic block copolymer was formed the self-assembled polymeric micelle system in the aqueous solution that the hydrophillic PEG was wraped the hydrophobic PHB. Generally, polymeric micelle forms the small particle between $10{\sim}200nm$. These polymeric micelle systems have been widely used for the drug delivery systems because they were biodegradable, biocompatible, non-toxic and patient compliant. The hydroxyl group of PEG was substituted with carboxyl group which has the reactivity to the ester group of PHB. Amphiphilic block copolymer was conjugated between PHB, and modified PEG at $176^{\circ}C$ which was higher than the melting point of PHB. Transesterification reaction was verified with DSC, FTIR, $^1H-NMR$. In the aqueous solution, critical micelle concentration (CMC) of the mPEG-co-PHB copolymer measured by the fluororescence scanning spectrometer was $5{\times}10^{-5}g/L$. The shape and size of the nanoparticle was taken by dynamic light scattering and atomic force microscopy. The size of the nanoparticle was about 130 nm and the shape was spherical. Our polymeric micelle system can be used as the passive targeting drug delivery system.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.81-90
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• 2010

We introduce a novel and versatile approach for preparing self-assembled nanoporous multilayered films with antireflective properties. Protonated polystyrene-block-poly (4-vinylpyrine) (PS-b-P4VP) and anionic polystyrene-block-poly (acrylic acid) (PS-b-PAA) block copolymer micelles (BCM) were used as building blocks for the layer-by-layer assembly of BCM multilayer films. BCM film growth is governed by electrostatic and hydrogen-bonding interactions between the oppositely BCMs. Both film porosity and film thickness are dependent upon the charge density of the micelles, with the porosity of the film controlled by the solution pH and the molecular weight (Mw) of the constituents. PS7K-b-P4VP28K/PS2K-b-PAA8K films prepared at pH 4 (for PS7K-b-P4VP28K) and pH 6 (for PS2K-b-PAA8K) are highly nanoporous and antireflective. In contrast, PS7K-b-P4VP28K/PS2K-b-PAA8K films assembled at pH 4/4 show a relatively dense surface morphology due to the decreased charge density of PS2K-b-PAA8K. Films formed from BCMs with increased PS block and decreased hydrophilic block (P4VP or PAA) size (e.g., PS36K-b-P4VP12K/PS16K-b-PAA4K at pH 4/4) were also nanoporous. Furthermore, we demonstrate that the nanostructured electrochemical sensors based on patterning methods show the electrochemical activities. Anionic poly(styrene sulfonate) (PSS) layers were selectively and uniformly deposited onto the catalase (CAT)-coated surface using the micro-contact printing method. The pH-induced charge reversal of catalase can provide the selective deposition of consecutive PE multilayers onto patterned PSS layers by causing the electrostatic repulsion between next PE layer and catalase. Based on this patterning method, the hybrid patterned multilayers composed of platinum nanoparticles (PtNP) and catalase were prepared and then their electrochemical properties were investigated from sensing $H_2O_2$ and NO gas. This study was based on the papers reported by our group. (J. Am. Chem. Soc. 128, 9935 (2006); Adv. Mater. 19, 4364 (2007); Electro. Mater. Lett. 3, 163 (2007)).

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.205-209
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• 2019

The exquisite structure and attractive biological properties of biominerals have great potential and increased interest for use in a wide range of medical and industrial applications. Calcium carbonate biomineralization, mainly controlled by shell matrix proteins, has been used as a representative model to understand the biomineralization mechanism. In this study, in vitro calcium carbonate crystallization was carried out under room temperature and atmospheric pressure using recombinant shell matrix protein GRP_BA and artificial shell matrix protein GG1234. Both proteins inhibited the growth of typical rhombohedral calcite crystals in the calcium carbonate crystallization using $CaCl_2$ solution and $(NH_4)_2CO_3$ vapor, and spherulitic calcite crystals with rosette-like structures were synthesized in both the presence of GRP_BA and GG1234. These results might be caused by the properties of block-like domain structure and intrinsically disordered proteins. We expect that this study can contribute to enhance understanding of the calcium carbonate biomineralization controlled by shell matrix proteins.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.423-435
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• 1984

The reproductive cycle of the small filefish, Rudarius ercodes was investigated based on the annual variations of gonadosomatic index(GSI) and hepatosomatic index(HSI) by electronic and photic microscophy. The specimens used were collected at the coastal area of Benden island, Sizuokagen, Japan, from September 1982 to August 1983. GSI began to increase from March, starting season of longer daylength and higher water temperature, and reached the maximum value between June and August. It began to decrease from September with the lowest value appearing between November and February without any evident variation. The annual variations of HSI were not distinct in male filefish and were negatively related to GSI in female : HSI decreased in the summer season when the ovary was getting mature and reached the maximum in the winter season when the ovary was getting retrogressive. The ovary consisted of a pair of saccular structure with numerous ovarian sacs branched toward the median cavity. Oogonia divided and proliferated along the germinal epithelium of the ovarian sac. Young oocytes with basophile cytoplasm showed several scattering nucleoli along the nuclear membrane. when the oocytes growing to about 300 ${\mu}m$, nuclear membrane to disappear with nucleus migrating toward the animal pole. The regions of protoplasm were extremely confined within the animal hemisphere in which most of cytoplasms were filled with yolk materials and oil drops. After ovulation, residual follicles and growing oocytes remaining in the ovarian sacs degenerated. But perinucleatic young oocytes without follicles formed were not degenerated, and growing continuously still in the next year. Mitochondria and endoplasmic reticula in the cytoplasm remarkably increased with oocytes maturing and yolk accumulating. Those were considered to be functionally related to the yolk accumulation. Five or six layers of possible vitellogenin, oval-shaped disc structures with high electron density, appeared in the apex of follicular processes stretching to the microvilli pits of mature oocytes. Testis consisting of a pair of lobular structures in the right and left were united in the posterior seminal vesicle, Cortex of testis was composed of several seminiferous tubules, and medulla consisting of many sperm ducts connected with tubules. Steroid hormone-secreting cells with numerous endoplasmic reticula and large mitochondria of well developed cristae were recognized in the interstitial cells of the growing testis. Axial filament of spermatozoon invaginated deeply in the central cavity of the nucleus and the head formed U-shape with acrosome severely lacking, mitochondria formed large globular paranuclei at the posterior head, and microtubular axoneme of the tail represented 9+9+2 type. The annual reproductive cycles could be divided into five successive stages : growth(March to July), maturation(May to September), Spawning(mid May to early October) and resting stages(October to February). The spawning peak occurred from June to August.

• Applied Microscopy
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• v.37 no.2
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• pp.83-91
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• 2007

The present study examined the epidermal changes of adhesive disks which occur during attachment in Parthenocissus tricuspidata using scanning and transmission electron microscopy. Several adhesive disks, each covered with a bract, develop from the shoot apical meristem during early development. In the initial stage, the adhesive disks are club-shaped and their upper and lower epidermis are indistinguishable. However, in the actively growing stage, they become spherical and both epidermis are clearly differentiated into the adventitious roots. Prior to wall attachment, the adhesive disks exhibit adaxial convex and abaxial concave shapes, and electron-dense substances are abundant in the vacuoles of epidermal cells. The peripheral area of the adhesive disk is adhered first to the wall surface, while the central area is drawn inward in a vacuum-like state during attachment. As the attachment progresses and the electron-dense substances continue to discharge, the upper and lower epidermis rapidly undergo deterioration and the disks shrink considerably. At this stage, structural changes of the lower epidermis occur much faster than in the upper one. The discharged substance is accumulated on the wall surface, and this aids the attachment of adhesive disks on the wall for long periods. In this manner, the shape and structure of the adhesive disk epidermis change drastically from initial growth to the mature stage. Further, the role of electron-dense substance and shrinkage of the disk during attachment has been discussed in Parthenocissus tricuspidata.