• 한국식품영양과학회지
• /
• 제28권5호
• /
• pp.1003-1009
• /
• 1999

For the isolation of probiotics which may be used for the human beings and animals, we have screened the microorganisms from chicken intestines which have acid and bile tolerance and the growth inhibition of pathogenic E. coli and Salmonella typhimurium. Among them, a strain which was identified as Lactobacillus salivarius had around 66% of survival after 2h incubation in the artificial gastric juice and 9% of survival after 24h incubation in the presence of 0.3% bile salts, and showed complete inhibition against both path ogenic E. coli and Salmonella typhimurium after 24 h coincubation. Its storage stability after lyophilization could be improved by adding polyvinylpyrrolidone.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제51권12호
• /
• pp.601-607
• /
• 2002

IPMC(Ionic Polymer Metal Composite)actuators were optimized for producing improved forces by changing multiple parameters including repetition of number of plating, surface electroding and additive(PVP)-treatment on reduction. The platinum electrode is deposited on the surface of the material where platinum particle stay in a dense form that appears to introduce a significant level of surface electrode resistance. Actuation tests were performed for such IPMC actuators under a low voltage. The test results show that the lower surface-electrode resistance generates higher actuation capability in the IPMC actuators. In order to investigate relaxation behavior of bending and repeatability in dry condition, the IPMC was coated by$rubber(KRATON^{TM})$to minimize the effect of water evaporation from IPMC. This actuator can be used in air with surface coating to avoid membrane drying.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.683-686
• /
• 2008

To diagnose vascular diseases from the viewpoint of hemodynamics, detailed quantitative hemodynamic information of related blood flows with a high spatial resolution of tens micrometer and a high temporal resolution in the order of millisecond were required. For investigating the hemodynamic phenomena of vascular circulatory diseases, a new diagnosing technique combining a medical radiography and PIV method was newly developed. This technique consisted of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulse-type X-ray source, and a synchronizer. Through several preliminary tests, the feasibility of the angiographic PIV technique was verified. For in-vivo measurements to real blood flows, we developed tracer microcapsules which were optimized to this system by encapsulating a contrast material of iodine with a matrix material of PVA (polyvinylpyrrolidone). In near future, the angiographic PIV technique would be useful for diagnosing hemodynamic phenomena of vascular diseases and for their early detection.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2003년도 학술대회 논문집
• /
• pp.146-148
• /
• 2003

SrZrO$_3$ resistive oxide barriers on Ag sheathed Bi2223 monocore tapes were prepared by the sol-gel and dip coating method to reduce AC coupling loss. The performance of the dip-coated SrZrO$_3$ thin films was evaluated in terms of bond strength and surface microstructure by varying the amount of PVP (polyvinylpyrrolidone) binder. Although bond strength and coating thickness increased as the PVP content rose, surface microcracking was more severe for the specimen containing higher content of PVP binder. It suggests that coating thickness and microcracking of the SrZrO$_3$ films on Bi2223 tapes was governed primarily by the amount of PVP binder.

• 멤브레인
• /
• 제4권1호
• /
• pp.46-56
• /
• 1994

새로운 복합막의 제조를 위하여 기존의 복합막에서 지지막으로 주로 사용되던 Polysulfone을 이보다 친수성이 뛰어난 Polyethersulfone막으로 대체하여 지지막을 직접 제조하고 이에 따른 복합막의 성능을 살펴 보았으며 이때 각 단계별로 제조막의 성능을 평가하여 각 단계별 최적 조건을 찾고자 하였다. 지지막은 Polythersulfone과 Polyvinylpyrrolidone의 조성에 따라 각각 실험하였으며, 활성층은 계면중합법에 의하여 m-Phenylene diamine과 Trimesoyl chloride를 반응시켜 제조하였다.

• Journal of Magnetics
• /
• 제13권3호
• /
• pp.106-109
• /
• 2008

Almost monodisperse iron oxide nanoparticles with an average particle size ranging from 5 to 43 nm were fabricated using an environmentally friendly starting material, ferrous acetate. The smallest particles were formed in the presence of a reductant, 1,2-dodecanediol, while the particle size increased with increasing concentration of dispersing agents. The dispersants consisted of various combinations of oleic acid, oleylamine, trioctylphosphine, and polyvinylpyrrolidone. The threshold temperature to form crystalline particles was found to be $240^{\circ}C$. The 43 nm nanoparticles exhibited a room temperature saturation magnetization and coercivity of 57 emu/g and 47 Oe, respectively.

• Bulletin of the Korean Chemical Society
• /
• 제30권2호
• /
• pp.297-301
• /
• 2009

We have developed the yttrium oxide (YNP) or ytterbium oxide (YbNP) nanoparticle/polymer matrices for the size-dependent separation of DNA ranging from 100 bp to 9,000 bp. High separation efficiency (> $10^6$ plates/m) and the baseline resolution for various DNA standards (100 bp, 500 bp, and 1 kbp DNA ladder) were obtained in 10 min with these matrices. The effects of concentrations of both polyethylene oxide (PEO) and nanoparticles were investigated and the highest performance was obtained at 0.02% PEO with 0.02% YNP or YbNP. Similar sieving power for both YNP and YbNP matrices was observed probably due to the similar sizes of nanoparticles, resulting in the formation of comparable sieving networks for DNA separation. For the reduction of electrosmotic flow, either dynamic or permanent coating of the capillary inner wall was compared and it turned out that PEO was superior to polyvinylpyrrolidone (PVP) or polyacrylamide (PAA) for better separation efficiency.

• 약학회지
• /
• 제25권4호
• /
• pp.187-192
• /
• 1981

In order to increase the dissolution rate on the mixture of sulfamethoxazole and trimethoprim (SMX-TMP), their coprecipitates with polyvinylpyrrolidone (PVP) were studied. Coprecipitates prepared with various ratios of SMX and TMP were examined such as hygroscopicity, apparent solubility, apparent partition coefficient and the dissolution behavior of SMX-TMP's coprecipitates and their physical mixtures. The hygroscopicity of coprecipitates were less than that of physical mixtures. The apparent solubility and dissolution rate of SMX-TMP's coprecipitates were found to be greatly increased. The dissolution rates of SMX and TMP in the coprecipitates were decreased when the ratio of two ingredients to PVP was smaller, and the dissolution rate of SMX was increased when the ratio of SMX to TMP was larger.

• Archives of Pharmacal Research
• /
• 제2권1호
• /
• pp.35-47
• /
• 1979

In order to increase the dissolution rate of furosemide(4-choro-N-furfury1-5-sulfamoy1 anthranilic acid_, various ratio coprecipitates with water-soluble polymers, such as polyvinylpyrrolidone and polythylene glycol, of different molecular weight, were prepared and quantitatively studied by comparing their dissolution characteristics of furosemide at powder state and at nondisintegrating disk state containing constant surface area at various temperatures and rotating velocities. The dissolution characteristics of furosemide from pure furosemide disks and 1:2(w/w) furosemide-PVP coprecipitate disks were in accordance with Noyes-Nernst equation and the rate constant of dissolution was proportional to the square root of rotating velocity of the disks. The intrinsic rate of dissoluton at 150 rpm, 37.deg.C was $2.21{\times}10^{-7}$ for the PVP 10, 000 COPRECIPITATE, $1.64{\times}10^{-7}$ for the PVP 40, 000 coprecipitate, and$ 1.44 {\times} 10^{-7}$for the PVP 360, 000 corprecipitate, while the rate was $1.27{\times}10^{-8}M/cm^{2} min$ for pure furosemide, repectively. The activation energy of dissolution was about 17, 000 for furosemide and about 7, 300 cal/mole for the 1:2 furosemide PVP 40, 000 coprecipitate, respectively.

• Bulletin of the Korean Chemical Society
• /
• 제30권11호
• /
• pp.2669-2674
• /
• 2009

Controlled reduction of silver alkylcarbamate complexes with hydrogen gas was investigated as a facile synthetic method for high concentrations of silver nanocolloids in organic solvent. Polyvinylpyrrolidone (PVP) was used to stabilize the silver colloids obtained from the chemical reduction. To determine optimum conditions for preparation of the stable and controlled silver colloids with the narrowest particle size and distribution, a large number of experiments were carried out involving variations in the concentrations of the silver 2-ethylhexylcarbamate (Ag-EHCB) complex, PVP, and 2-propanol. The initial colloid had a mean particle diameter between 5$\sim$50 nm, as measured by transmission electron microscopy, and exhibited a sharp absorption band in the UV region with a maximum size near 420 nm. After treatment with a reducing agent, the colloids were characterized by ultraviolet-visible spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy.