• Archives of Pharmacal Research
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• v.28 no.5
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• pp.612-618
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• 2005

A mucoadhesive microsphere was prepared by an interpolymer complexation and solvent evaporation method, using chitosan and poly(acrylic acid) (PAA), to prolong the gastric resid ence time of the delivery system. The Fourier transform infrared results showed that microspheres were formed by an electrostatic interaction between the carboxyl groups of the PAA and the amine groups of the chitosan. X-ray diffraction and differential scanning calorimetry analysis showed that the enrofloxacin in the chitosan-PAA microsphere was molecularly dispersed in an amorphous state. Scanning electron microscopy of the surface and the quantity of mucin attached to the microspheres indicated that chitosan-PAA microspheres had a higher affinity for mucin than those of chitosan alone. The swelling and dissolution of the chitosan-PAA microspheres were found to be dependent on the pH of the medium. The rate of enrofloxacin released from the chitosan-PAA microspheres was slower at higher pH; therefore, based on their mucoadhesive properties and morphology, the chitosan-PAA microspheres can be used as a mucoadhesive oral drug delivery system.

• Archives of Pharmacal Research
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• v.8 no.1
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• pp.7-14
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• 1985

Membrane-coated tablet of isonicotinic acid hydrazide (INAH) which releases INAH at the zero-order kinetics was deveoped. It consisted of a soluble tablet core surrounded by a porous membrane which controls the diffusion rate. Tablet cores were prepared by compressing granules of INAH and polyvinyl chloride (PVC) dissolved in methyl ethyl ketone in which micronized sucrose were suspended. Diffusion rate of INAH from the tablet through the membrane was constant until the loaded INAH in the core was almost released. The rate was independent of pH of the dissolution medium. Water-soluble sucrose particles behaved as a poreproducing material in the water-insoluble PVC film coat. The pH independency of the rate was probably due to the high solubility of INAH in the water of wide pH range. The diffusion rate of INAH could be controlled by chnaging the composition of the membrane or the coat weight. This membrane-coated INAH tablet seemed to be a powerful candidate for the controlled release drug delivery system (DDS) of INAH or other highly watersoluble drugs.

• Korean Journal of Materials Research
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• v.29 no.2
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• pp.65-72
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• 2019

Dual porous structures are observed for the first time on a metallic Cu surface underneath anodic Cu oxide by the application of an anodizing voltage to Cu in oxalic acid. The as-prepared porous Cu surface contains macropores of less than $1{\mu}m$ diameter and mesopores of about tens of nanometers diameter with circular shapes. The size and density (number of pores/area) of the macropores are dependent on the applied voltage. It is likely that the localized dissolution (corrosion) of Cu in oxalic acid under the anodizing voltages is responsible for the formation of the mesopores, and the combination of a number of the mesopores might create the macropores, especially under a relatively high anodizing voltages or a prolonged anodizing time. The variations of pore structure (especailly macropores) with applied voltage and time are reasonably explained on the basis of the proposed mechanism of pore formation.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.408.1-408.1
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• 2002

A interpolymer complexes composed of poly(acrylic acid)(PAA) and po!y(vinyl alcohol)(PVA) were prepared by template polymerization of acrylic acid in the presence of PVA for mucoadhesive drug delivery. FT -IR results showed that the PAA/PVA interpolymer complex was formed by hydrogen bonding between the carboxyl groups of PAA and the hydroxyl group of PVA. The dissolution rate or the swelling ratio of the PAA/PVA interpolymer complexes was dependent on the pH and molecular weight of PVA that was used as a template. (omitted)

• Archives of Pharmacal Research
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• v.18 no.4
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• pp.224-230
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• 1995

Recently, many attempts have been made to use hydrogels of various polymers as delivery systems of various drugs and bioactive materials to prolong and control their phamacological activities. In this study, we have evaluated the physico-chemical properties of methacrylic acid-methyacrylic acid methyl ester copolymer 9Eudispert mv)m a acrylic resin hydorgel, and its application to transdermal delivery system. In the dissolution tests, the release rate of salicylic acid (SA) and sodium salicylate (SOd. SA) were faster than lidocain (LD) and lidocain-HCl(LD-HCl). As the concentration of Eudispert mv polymer increased, the extensibility of Eudispert mu hydrogel decreased, whereas the swelling ratio increased. The more NaOH and polymer concentration increased, the more osmotic pressure linearly increased. The skin permeation of Sod. SA, an acidic model drug, was remarkably enhanced by Eudispert mv hydrogel. All fatty acids, except for Sod. glycolate, dramatically increased the skin permeation flux in Eudispert mu hydrogel containing LD-Hcl, a basic model drug. Consequently, it is suggested that Eudispert mv hydrogel may be used as potential transdermal delivery vehicle.

• Journal of Marine Bioscience and Biotechnology
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• v.11 no.2
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• pp.36-41
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• 2019

This study was conducted to analyze the difference in mechanically improved properties by distinguishing α-chitin and β-chitin for Poly(L-lactic acid)(PLLA). First, dissolution of chitins was established by mixing polar solvents hexafluoroisopropanol (HFIP) and trifluoroacetic acid (TFA) in appropriate proportions. Under these conditions, the dissolved chitin was used for electrospinning with other polymers. The electrospun nanofibers of the PLLA and chitins were successfully produced. Compared to the pristine state, when chitin was added to PLLA, the tensile strength increased 1.41 times (α-chitin), by 1.61 times (β- chitin), respectively. Based on this, it was confirmed that α- and β- chitin could be strategically used for different polymers. The results also suggest that chitin can be applied to various fields as good reinforcing material as well as electrospinning.

• Journal of the Korean institute of surface engineering
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• v.43 no.4
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• pp.205-210
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• 2010

The A106 Gr B low carbon steel, which was used in the electric power plants and heavy chemical plants, was welded by multi-pass arc welding. The heat affected zone (HAZ) formed by welding was corroded in acid chloride solution, or in saturated $H_2S$ containing acid chloride solution, or in saturated $H_2S$ containing acid chloride solution under applied current. In this order of corrosion solution, the rate of corrosion increased, because $H_2S$ accelerated the iron dissolution, hydrogen evolution, and the formation of nonprotective FeS, whereas the applied current accelerated the electrochemical reaction. The scales formed in acid chloride solution consisted primarily of $Fe_3O_4$, while those formed in $H_2S$ containing acid chloride solution consisted primarily of $Fe_3O_4$ and FeS.

• Economic and Environmental Geology
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• v.27 no.6
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• pp.507-521
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• 1994

Bentonite occurs in the Janggi Conglomerate of Tertiary age and consists mainly of montmorillonite with Mg as predominant interlayer cations. The bentonite was reacted with various concentrations of sulfuric acid (0.8~1.5M) for various reaction time (1-10h) at $103^{\circ}C$. Cation exchange capacity, exchangeable cations, surface area and solid acidity of the original bulk and acid activated bentonites were measured. Chemical analysis, X-ray diffraction, differential thermal analysis and infrared spectroscopy were used to characterize the changes in structure and properties of the acid activated bentonite. The dissolution of octahedral cations occurs not only from the edge of the clay platelets but also throughout the whole clay structure creating vacant octahedral sites. These lattice defects are created by $H^+$ diffused into the smectite layers. The cations leached possibly from the octahedral sheets are adsorbed on the interlayer exchange sites. They are exchanged with hydronium ions again by stronger acid attack. These reactions create wedge-shaped pores resulting in the increase of the surface area and the changes the morphology in the lattice structure.

• Journal of Pharmaceutical Investigation
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• v.15 no.1
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• pp.8-14
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• 1985

Data obtained from X-ray diffractometry, thermal analysis, IR spectroscopy and microscopic observation were used for the identification and characterization of four crystalline modifications of piroxicam. form a was crystallized from sodium hydroxide-hydrochloric acid and from c was obtained by crystallization from toluene. Form b and d was crystallized from methanol under the different temperature conditions. Relative rates of dissolution and solubility of four crystal forms of piroxicam in distilled water were measured.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1252-1254
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• 2005

Recently, PDP barrier ribs require the formation of complex structure so that they are usually formed by etching method. For producing the fine ribs structure, during the etching process the metal ions of matrix (glass) of barrier materials should be understood on the etching mechanism with etching condition. We analyzed the quantity of Pb, Si, and B ions from the etch solution as a function of etching time.