• Title/Summary/Keyword: Dispersing

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Enhancement of Dissolution Properties of Poorly Soluble Drugs(IV) -Micronization of Furosemide by Recrystallization Method- (난용성 약물의 용출 증가(제4보) -재결정법에 의한 푸로세미드의 미세화-)

  • Koh, Ik-Bae;Shin, Sang-Chul;Oh, In-Joon
    • Journal of Pharmaceutical Investigation
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    • v.18 no.2
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    • pp.55-59
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    • 1988
  • The size of furosemide was reduced by the recrystallization method in order to increase the dissolution rate of the drug. Surfactants or hydrophilic polymers were used to suppress the aggregation in the crystal formation-growth process of microparticles by dispersing action. Dissolution rate of microparticles increased remarkably due to the size reduction of microparticle. The particle size decreased with increasing the concentration of the drug and the dispersing agents, i.e., surfactants or hydrophilic polymers. No polymorphic transition occurred during the microcrystallization process, but the habit of crystal formation was altered in the case of anionic surfactant.

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Powder Injection Molding Technique of Fabricating Cemented Tungsten Carbide Balls for Milling and Dispersing Nano-Powder (나노분말 분쇄 및 분산용 고성능 초경합금 볼의 제조를 위한 분말사출성형 공법)

  • Chung, Seong-Taek;Cho, Ju-Hyun;Lee, Min-Cheol;Kwon, Young-Sam;Joun, Man-Soo
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.37-42
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    • 2007
  • We present a powder injection molding technique of fabricating cemented tungsten carbide(WC) balls for milling and dispersing nano-powder in this paper. The conventional powder metallurgy approach is investigated to reveal its drawbacks of density non-homogeneity. New procedures of powder injection molding for the homogeneous high-precision WC balls, involving the binding process, powder injection molding process and sintering process, are presented in detail. Each process is investigated empirically and numerically to obtain its engineering information, which can used for process optimization.

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The Manufacture of Conductive paste for OTFT source & drain contacts Fabricated by Direct printing method (Direct Printing법에 의해 제작된 OTFT용 source & drain 전극용 전도성 페이스트 제조)

  • Lee, Mi-Young;Nam, Su-Yong;Kim, Seong-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.384-385
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    • 2006
  • We studied about conductive pastes of the source-drain contacts for OTFTs(organic thin-film transistors) fabricated by direct printing(screen printing) method. We used Ag and conductive carbon black powder as the conductive fillers of pastes. The conductive pastes were manufactured by various dispersing agents and dispersing conditions and source-drain contacts with $100{\mu}m$ of channel length were fabricated. We could obtain the OTFTs which exhibited different field-effect behaviors over a range of source-dram and gate voltages depending on a kind of conductive fillers used conductive pastes.

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Microencapsulation of Nalidixic Acid Using Eudragit RL (Nalidixic Acid의 Eudragit RL Microencapsulation에 관한 연구)

  • Ku, Young-Soon;Choi, Kyung-Joo
    • YAKHAK HOEJI
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    • v.34 no.3
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    • pp.199-205
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    • 1990
  • Microencapsulation of nalidixic acid using Eudragit RL, a methacrylic acid copolymer was investigated. Microcapsules were prepared by dispersing the drug solution in liquid paraffing using aluminium tristearate as dispersing agent. The preparation of the microcapsules showed high reprodulibility in particle size, shape and the drug content. The dissolution rates of Nalidixic acid from the these microcapsules considerably decreased as compared with that from Nalidixic acid powder and Nalidixic acid-Eudragit RL solid dispersions. The release of Nalidixic acid increased with increasing percentage of aluminium tristearate added to the microcapsules.

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Dielectric Properties of Epoxy/Organically Modified Layered Silicate Nanocomposites (에폭시/유기적으로 변경된 층상실리케이트가 충진 된 나노콤포지트의 유전특성)

  • Park, Jae-Jun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.2
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    • pp.188-193
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    • 2008
  • Epoxy/Organically Modified Layered Silicate Nanocomposites were prepared by dispersing synthetic layered silicate modified with alkyl ammonium ions. In the dispersing process, the organically modified layered silicate were mixed in epoxy resin with shearing, and aggregation of the silicate were removed by centrifugal separation after mixing epoxy resin and silicates. Micrographs taken by transmission electron microscopy(TEM) indicate that the nanocomposites have a mixed morphology including both parallel silicate layers and exfoliated silicate layers area, As the thermal properties, the glass transition temperature of the nanocomposites was shifted to a higher temperature($+6^{\circ}C$)than pure epoxy. Furthermore, dispersion of OMLS will prevented relative permittivity from increasing at a high temperature above the glass transition temperature.

A Study on Microencapsulation of Perfume and Antibiotics by In-situ Polymerzation(I) (In-situ 중합에 의한 향료와 항균제의 마이크로 캡슐화에 관한 연구(I))

  • 박차철;정영진;박찬영;민성기
    • Textile Coloration and Finishing
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    • v.9 no.6
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    • pp.68-73
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    • 1997
  • Urea/formaldehyde(UF) and melamine/formaldehyde(MF) microcapsules containing perfume and 2,4,4'-trichlroro-2-hydroxydiphenyl ether(DP) were prepared by the in-situ polymerization using urea and formaldehyde. Effects of dispersing agent, accelerating agent, formaldehyde, agitation speed on the mean diameter of microcapsules were investigated. The diameter of microcapsule was decreased with increasing dispersing agent concentration. A slight increase in the diameter was observed when the concentration of film forming material was increased. The diameter of microcapsule was decreased with increasing agitation speed up to 8,000rpm. The mean diameters of UF microcapsule prepared at 8,000rpm are about 3$\mu$m. A slight decrease in the diameter was observed when the concentration of resorcinol was increased.

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The Effects of Task Complexity for Text Summarization by Korean Adult EFL Learners

  • Lee, Haemoon;Park, Heesoo
    • Journal of English Language & Literature
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    • v.57 no.6
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    • pp.911-938
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    • 2011
  • The present study examined the effect of two variables of task complexity, reasoning demand and time pressure, each from the resourcedirecting and resource-dispersing dimension in Robinson's (2001) framework of task classification. Reasoning demand was operationalized as the two types of texts to read and summarize, expository and argumentative. Time pressure was operationalized as the two modes of performance, oral and written. Six university students summarized the two types of text orally and twenty four students from the same school summarized them in the written form. Results from t test and ANCOVA showed that in the oral mode, reasoning demand tends to heighten the complexity of the language used in the summary in competition with accuracy but such an effect disappeared in the written mode. It was interpreted that the degree of time pressure is not the only difference between the oral and written modes but that the two modes may be fundamentally different cognitive tasks, and that Robinson's (2001) and Skehan's (1998) models were differentially supported by the oral mode of tasks but not by the written mode of the tasks.

The Study on the Energy and Fluid Metabolism and the Pathology and Symptomatology of Taeeumin based on The Discourse on Viscera and Bowels of Donguisusebowon (『동의수세보원(東醫壽世保元)』 「장부론(臟腑論)」에 근거한 기액대사(氣液代謝)와 태음인(太陰人) 병리병증(病理病證) 고찰(考察))

  • Lee, Jun-Hee;Lee, Eui-Ju;Koh, Byung-Hee
    • Journal of Sasang Constitutional Medicine
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    • v.24 no.4
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    • pp.1-16
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    • 2012
  • Objectives : We aimed to analyze the meanings of the energy and fluid metabolism in the Discourse on Viscera and Bowels of Donguisusebowon, and to find the clues for the explanation of the pathology and symptomatology of Taeeumin. Methods : The Discourse on Viscera and Bowels of Donguisusebowon was reviewed and examined for relevant information on the energy and fluid metabolism from the structural and the functional point of view respectively. And, based on the derived meanings of the energy and fluid metabolism, the pathology and symptomatology of Taeeumin were analyzed. Results and Conclusions : 1. The meanings of the energy and fluid metabolism can be explained by the different attributes of the energy and fluid produced from the esophagus and the small intestine, and the different function of exhaling-dispersing and inhaling-concentrating in the different tract of circulation such as Lung affiliation (esophagus, skin, ear and lung) and Liver affiliation (small intestine, flesh, nose and liver). 2. The Exterior disease of Taeeumin starts with the weakness of exhaling-dispersing function at the skin, and leads to the dysfunction of the esophagus and the lung sequently. The dysfunction of the lung aggravates that of the skin and the esophagus. 3. The Interior disease of Taeeumin begins with excess of the inhaling-concentrating functions at the flesh and the small intestine, and leads to the dysfunction of the lung, which induces the dysfunction of exhaling-concentration at the skin and esophagus. And, this disparities between exhaling-dispersing and inhaling-concentrating functions exasperate the problem at the flesh and the small intestine.

Effects of Various Formulations on Bioavailability of Acetaminophen Soft Gelatin Capsules in Rabbits (토끼에서 아세트아미노펜 연집캅셀제의 생체이용율에 미치는 제제처방들의 영향)

  • Park, Gee-Bae;Lee, Yong-Suk;Choi, Myung-Ho;Lee, Do-Ik;Lee, Kwang-Pyo
    • YAKHAK HOEJI
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    • v.36 no.6
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    • pp.598-603
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    • 1992
  • The purpose of this study was to assess the effect of three formulations; product A (polyethylene glycol was used as a main dispersing agent), product B (wax mixture was used as a main dispersing agent) and product C(silicon dioxide was used as a main dispersing agent) on bioavailability of acetaminophen soft gelatin capsules(softgels) and to develop an effective acetaminophen softgel which exhibits an excellent bioavailability. Acetaminophen softgels of various formulations were prepared as 4 minim round type by rotary die method. Four softgels of the three formulation (A, B, C), each of which contained 50 mg acetaminophen, were administered orally to 12 normal healthy rabbits using a three-way cross over design. Plasma acetaminophen concentrations were measured by HPLC. The results obtained in this study were as follows: 1. The Tmax rank order of acetaminophen softgel was C$(63.75{\pm}10.62\;min)$>A$(36.25{\pm}5.37\;min)$>B$(35{\pm}6.74\;min)$. 2. The decreasing Cmax order of softgel product was A$(93.51{\pm}0.55\;{\mu}g/ml)$>B$(3.16{\pm}0.37\;{\mu}g/ml)$>C$(2.6{\pm}0.55\;{\mu}g/ml)$. 3. The $[AUC]^{\infty}_0$ rank order for three acetaminophen softgel formulations was A $(14.89{\pm}1.56\;{\mu}g/ml{\cdot}min)$ >B$(14.39{\pm}1.43\;{\mu}g/ml{\cdot}min)$>C$(11.45{\pm}1.49\;{\mu}g/ml{\cdot}min)$. 4. Pharmacokinetic parameters such as Tmax, Cmax and $[AUC]^{\infty}_0$ of product A and B did not differ significantly(p>0.05). On the other hand, those of product C were significantly different(p>0.05).

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