• 한국재료학회지
• /
• 제29권6호
• /
• pp.385-391
• /
• 2019

In the present study, vanadium oxide($V_2O_5$) films for electrochromic(EC) application are fabricated using sol-gel spin coating method. In order to optimize the EC performance of the $V_2O_5$ films, we adjust the amounts of polyvinylpyrrolidone(PVP) added to the solution at 0, 5, 10, and 15 wt%. Due to the effect of added PVP on the $V_2O_5$ films, the obtained films show increases of film thickness and crystallinity. Compared to other samples, optimum weight percent(10 wt%) of PVP led to superior EC performance with transmittance modulation(45.43 %), responding speeds(6.0 s at colored state and 6.2 s at bleached state), and coloration efficiency($29.8cm^2/C$). This performance improvement can be mainly attributed to the enhanced electrical conductivity and electrochemical activity due to the increased crystallinity and thickness of the $V_2O_5$ films. Therefore, $V_2O_5$ films fabricated with optimized amount of PVP can be a promising EC material for high-performance EC devices.

• 센서학회지
• /
• 제30권2호
• /
• pp.94-98
• /
• 2021

In this study, pure and Co3O4/CoFe2O4-loaded Indium oxide (In2O3) nanofibers were synthesized by the electrospinning of an Indium/Polyvinylpyrrolidone precursor solution containing cobalt and iron bimetallic zeolitic imidazolate frameworks and subsequent heat treatment. The ethanol, toluene, p-xylene, benzene, carbon monodxide, and hydrogen gas sensing characteristics of the solution were measured at 250-400 ℃. 0.5 at%-Co3O4/CoFe2O4-loaded In2O3 nanofibers exhibited extreme response (resistance ratio - 1) to 5 ppm of ethanol (210.5) at 250 ℃ and excellent selectivity over the interfering gases. In contrast, pure In2O3 nanofibers exhibited relatively low responses to all the analyte gases and low selectivity above 250-400 ℃. The superior response and selectivity toward ethanol is explained by the catalytic roles of Co3O4 and CoFe2O4 in gas sensing reaction and the electronic sensitization induced by the formation of p (Co3O4/CoFe2O4)-n (In2O3) junctions.

• Korean Chemical Engineering Research
• /
• 제52권6호
• /
• pp.814-820
• /
• 2014

본 연구에서는 토크 측정과 고압 시차주사 열량계를 이용하여 pyrrolidone, caprolactam, acrylamide 계열 수용성 고분자들의 하이드레이트 저해 성능을 평가하였다. 실험 결과, 세 종류의 고분자가 모두 동역학적인 하이드레이트 생성억제제 효과를 나타내는 것으로 확인되었으며, 특히 0.5 wt% polyvinylcaprolactam (PVCap)의 경우 34.4분의 하이드레이트 유도 시간, 15.9 K의 subcooling 성능을 보이며 12.3 분, 6.0 K의 순수 물 시스템보다 월등한 저해 성능을 나타내었다. 0.5 wt% polyvinylpyrrolidone (PVP)의 경우 중간 정도의 저해 성능을 보였으며, polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA)의 경우 각각 0.5 wt%와 5.0 wt%의 농도에서 미미한 하이드레이트 저해 성능을 보였다. 반면에 생성된 하이드레이트 입자의 성장속도와 생성 양에서는 PAM-co-AA가 PVCap과 더불어 가장 월등한 저해 효과를 나타내었다. 또 다른 주요 성능 평가 요소 중 하나인 토크 변화의 경우에는 PVCap이 평균 토크 6.4 N cm로 가장 좋은 성능을 보였으며, 0.5 wt%의 PAM-co-AA 시스템이 평균 7.2 N cm의 값으로 그 뒤를 이었다. 고압 시차주사 열량계를 이용한 수용성 고분자 물질의 저해 성능 평가 실험의 결과는 autoclave 실험의 결과와 유사하였다. PVCap을 첨가한 경우 하이드레이트가 생성되기까지의 유도시간이 가장 길어서 저해성능이 뛰어난 것을 확인하였다.

• 한국가축번식학회지
• /
• 제25권1호
• /
• pp.19-28
• /
• 2001

소 미성숙 난자 (GV stage)의 동결에 중요한 영향을 미치는 평형시간과 동결속도가 융해후 생존율 및 배발달율에 미치는 영향을 알아보기 위하여 미성숙 난자의 동결 융해후 체외성숙, 체외수정 및 배반포 발달 능력을 알아보았다. 본 실험에 사용한 동결액의 조성은 침투성 보호제(Ethylene glycol, EG)와 비 침투성 보호제(Ficoll ; F, polyvinylpyrrolidone; PVP, Sucrose; S, Trehalose ; T)를 혼합하여 네가지 조성의 동결액을 준비하였다. 즉EFT: 10% EG + 5% F + 0.05M T, EFS: 10% EG + 5% F + 0.05M S, EPT: 10% EG + 5% P + 0.05M T, EPS: 10% EG + 5% P + 0.05M S이다. 네가지 동격액 (EFT, EFS, EPT, EPS)을 이용하여 미성숙 소 난자 (GV stage)의 최적 평형 시간을 알아보기 위하여 각각 10, 15, 20분의 평형후 동결 응해하였다(실험 1). EPT액에서 15분의 평형시간이 가장 좋은 생존율을 나타내었다(83.05%). 동결 속도가 생존율에 미치는 영향을 알아보기 위하여 각각 17$^{\circ}C$, $0^{\circ}C$ 및 -6$^{\circ}C$로 동결 속도를 달리 설정하여 동결 융해를 실시하였다(실험 2). 융해후 생존율은 대부분 $0^{\circ}C$로 시작하는 동결속도에서 가장 좋은 성적을 나타내었다. 즉 EFT, EPT, EPS에서 각각 78.1, 73.7, 74.7%의 생존율을 나타내었다. 동결융해 하지 않은 신선란과 동결 응해한 미성숙 난자의 핵 성숙율은 각각 87.2%와 62.3%가 metaphase II로 발달하였다. 동결 응해 미성숙 난자의 IVM, IVF후 난분할율은 EFT, EFS, EPT 그리고 EPS에서 각각 32.57, 23.21, 38.39 그리고 21.33%로 EPT에서 가장 높았으나 유의차는 없었다. 배반포 발달율도 각각 2.86, 3.57, 4.46 그리고 0.47%로서 유의적인 차이를 보이지 않았다. 동결융해 미성숙 난자의 IVM, IVF후 TCM199와 CR-1aa배양액을 이용하여 소 난관상피세포(BOEC)와 공배양 한 결과 배양액의 종류에 따라 난분할율과 배반포 발달율에서는 차이를 보이지 않았다. 또한 미성숙 소 난자의 동결 융해후 얻은 배반포 수정란을 자연발정 Holstein 수란우에 7일째 비외과적으로 이식하였다. 6두에 9개의 수정란을 이식하여 2두가 임신이 확인되었으나 1두는 45일경 유산되었고, 나머지 1두는 장기재태로 분만을 유도하였으나 사산되었다.

• 한국결정성장학회지
• /
• 제31권1호
• /
• pp.8-15
• /
• 2021

TiO2는 물리적, 화학적 안정성이 높고, 신체에 무해하여 태양전지, 치과용 임플란트 및 광촉매 같은 다양한 분야에서 사용되어 왔다. 비표면적이 큰 TiO2 나노섬유는 생체 친화성 제품에서 좋은 반응성과 공기 및 수질 정화시 우수한 광촉매 특성을 보여주었다. TiO2 나노섬유를 제조하기 위해 전기방사법을 사용하였으며, 제조 변수에 따른 직경 변화를 관찰하기 위해 precursor 성분 변수와 공정 변수로 구분하여 미세구조 변화를 분석하였다. Precursor 성분 변수로는 PVP(Polyvinylpyrrolidone) 및 TTIP(Titanium(IV) isopropoxide)의 농도를 선택하였고, 공정 변수로는 주입 속도와 인가 전압을 선택하였다. TiO2 나노섬유의 미세구조와 결정구조는 FE-SEM(Field emission scanning electron microscope)와 XRD(X-ray diffraction)을 이용하여 분석하였다. 450℃에서 3시간 열처리 공정을 통해, 평균 직경 약 0.27 ㎛에서 1.31 ㎛를 갖는 asspun TiO2 나노섬유가 0.22 ㎛에서부터 0.78 ㎛의 평균 직경을 갖는 anatase 상의 TiO2 나노섬유로 상전이 됨을 확인할 수 있었다. 평균 직경 0.22 ㎛의 anatase TiO2 나노섬유는 비 표면적 증대에 의한 광촉매 특성 향상을 기대할 수 있다. 또한 TiO2 나노섬유의 직경 변화를 위해서는 주입 속도 및 인가 전압과 같은 공정 변수보다는 PVP 농도 및 TTIP 농도와 같은 precursor 성분 변수를 제어하는 것이 더욱 효과적이었다.

• Clinical and Experimental Reproductive Medicine
• /
• 제27권4호
• /
• pp.339-344
• /
• 2000

Objective: To evaluate silane-coated silica particles (Sil-select) as an alternative to polyvinylpyrrolidone-coated particles (Percoll) for gradient separation of spermatozoa, for use in assisted reproduction. Methods: 20 normal semen based on WHO criteria were included in this study. Recovery of motile and morphologically normal spermatozoa after using two-layer Percoll and Sil-select gradient respectively was recorded. Motility, HOST (hypoosmotic swelling test) and the detection of malondialdehyde for LPO (lipid peroxidation) after 24 h of incubation at $37^{\circ}C$ in a 5% $CO_2$ incubator were compared. Results: Percoll (78.5%) and Sil-select (79.1%) showed a significant increase in the motility compared to ejaculate (60.9%) but no difference between Percoll and Sil-select. Normal sperm morphology significantly increased after Percoll (57.6%) and Sil-select (53.7%) compared to ejaculate (35.8%) but no difference between Percoll and Sil-select. No differences in the recovery of motile spermatozoa and motility, HOST and the production of malondialdehyde after 24 h incubation were found when comparing the use of Percoll and Sil-select. Conclusion: Sil-select seems to be an attractive alternative to Percoll for sperm separation in assisted reproduction.

• 대한핵의학회지
• /
• 제23권1호
• /
• pp.71-83
• /
• 1989

For the development of $^{99m}Tc-labelled$ antimony sulfide colloid and hydroxyethyl starch, various experiments such as preparation of colloid, control of the distribution of particle size, establishment of labelling conditions, determination of labelling yield and radiochemical purity, examination of stability, and organ imagings of rabbits etc. were carried out. 1) Antimony sulfide colloid was readily prepared by the reaction of aqueous solution of antimony potassium tartrate with hydrogen sulfide generated by treating ferrous sulfide with dilute sulfuric acid. The colloid could be stabilized by adding small amount of polyvinylpyrrolidone. 2) Electron microscopy analysis exhibited the distribution of colloid size in the range of $1\sim15nm$ with a major portion of 9 m. The colloid solution was sterilized by membrane filtration $(0.2{\mu}m)$ and then stored at $4^{\circ}C$. This sterilized colloid was so stable that it was usable at least for one year. 3) The antimony sulfide colloid was labelled by adding sodium $pertechnetate-^{99m}Tc$ solution to the reaction vial, followed by adding hydrochloric acid and then boiled for 30 min. The optimal pH of the reaction mixture was found to be in the range of $1.3\sim1.4$. Instant thin layer chromatography (ITLC) analysis showed high labelling yield of above 99.5%. This labelled colloid maintained high radio-chemical purity of above 99% until 10 hours after labelling. 4) Animal studies showed high uptake of $^{99m}Tc-Sb_2S_3$ colloid at lymph vessels and nodes indicating a suitable agent for lymphoscintigraphy. Satisfactory results were also abtained in other clinical studies. 5) Hydroxyethyl starch (HES $0.6\sim1.0%$) was labelled with $Na^{99m}TcO_4$ in the presence of $SnCl_2$ with high labelling yield of above 99.5%. The optimal pH of the reaction mixture was in the range of $1.8\sim2.0$. $^{99m}Tc-HES$ maintained high radiochemical purity of above 99% until 10 hours after labelling. 6) Animal studies showed that $^{99m}Tc-HES$ migrated more rapidly from the injection sites into the lymph vessels than $^{99m}Tc-Sb_2S_3$ colloid while less amount of the former was uptaken at lymph nodes than that of the latter. Similar phenomenon was also observed in other clinical studies. As a result, $^{99m}Tc-Sb_2S_3$ colloid was found to be more effective lymphoscintigraphic agent than $^{99m}Tc-HES$.

• Journal of Animal Science and Technology
• /
• 제55권5호
• /
• pp.417-425
• /
• 2013

동결 닭 PGCs의 생식계열 키메라를 이용한 생체에의 복원을 실용화 하기 위해서는, 닭 PGCs의 동결보존기술의 향상에 의해 동결 및 융해 후의 많은 생존세포를 확보 하는 것과, 생식계열 키메라의 제작효율을 높이는 것이 반드시 필요하다. 닭 PGCs는 배양 5.5일령의 닭 원시생식선으로부터 채취하고, ACS 방법에 의해서 순수 닭 PGCs를 분리했다. 닭 PGCs의 동결보존실험결과 다음의 4종류의 동결방법을 각각 비교 검토했다. 1. 플라스틱 스트로에 의한 완만동결법 (SF), 동결보호물질은 2M 에틸렌 글리콜 (EG), 2. 스트로에 의한 급속동결법 (RF), 8M EG + 7% PVP, 3. 동결용 Cryotube에 의한 SF, 2M EG, 4. 튜브에 의한 SF, 10% DMSO. 동결 및 융해 후의 PGCs의 생존율은 각각 76.4%, 70.6%, 80.5%, 78.1%로 관찰되었다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제16권1호
• /
• pp.23-28
• /
• 2003

The present study was undertaken to investigate the effects of PVP concentration and exposure temperature to vitrification solution on the post-thaw survival, in vitro maturation and development of immature bovine oocytes (germinal vesicle stage). The vitrification solution (VS) consisted of 40% ethylene glycol (EG)+0.5 M sucrose (S)+10% FBS. PVP was added to VS: 0%, 5% or 10%. The cumulus-oocyte complexes (COCs) were diluted in VS as one step, after 2 min the COCs were loaded in straw and vitrified by direct immersion into liquid nitrogen. For thawing, the straws were plunged into $30^{\circ}C$ water bath for 10s. After thawing, the oocytes were diluted in 0.5 M (in DPBS with 10% FBS) sucrose solution for 5 min. The survival rate (FDA-test and trypan blue) of immature bovine oocytes was measured. The survival rate was higher in 5% PVP (91.5%) than in 0% (64.2%) or in 10% PVP (79.7%). The proportion of metaphase II formation was 69.35% in control (no vitrified COCs), 9.3% in 40% EG+0.5 M S+0% PVP and 21.05% in 40% EG+0.5 M S+5% PVP (p<0.05). The effect of room temperature ($25^{\circ}C$ for 10 min) and cold temperature ($4^{\circ}C$ for 10 min) on COCs were determined in this study. After IVF, the cleavage and blastocysts rate of oocytes exposed to room temperature and cold temperature in VS+5% PVP was significantly different (2 cell: 63.20% vs 37.97%, blastocysts: 18.40% vs 2.53%). The cleavage rates of frozen-thawed oocytes were 20.53% with PVP and 22.13% without PVP (p>0.05). Two out of 151 oocytes (1.32%) developed to blastocyst stage after frozen-thawed with 5% PVP (p>0.05). Development of oocytes after frozen-thawing to the 2 cell were not significantly affected with or without PVP following IVF. However, the vitrification of immature bovine oocytes with PVP maintained the ability to develop to the blastocyst stage after IVM-IVF and IVC, while no blastocysts were obtained from oocytes vitrified without PVP. These results suggested that PVP has a protective role for vitrification of immature bovine oocytes as far as survival is concerned, however, the protection was not sufficient enough to support blastocyst formation.

• Asian-Australasian Journal of Animal Sciences
• /
• 제20권12호
• /
• pp.1820-1826
• /
• 2007

In this study, we conducted various experiments in order to develop enhanced cultural conditions for in vitro-produced porcine embryos. All embryos were produced by in vitro maturation (IVM) and fertilization (IVF) of immature oocytes from abattoir-derived ovaries. In experiment 1, we cultured IVF embryos in 4 different groups, namely, 0% bovine serum albumin (BSA), 3% BSA, 0.05% Polyvinyl alcohol (PVA), and 0.5% Polyvinylpyrrolidone (PVP) added to the basal fluid cultural medium, Porcine zygote medium 3 (PZM-3). The rates of embryo development were higher in the group where the PZM-3 media had been supplemented with 3% BSA than the other groups. While not statistically significant, the percent of blastocysts and hatched blastocytes were 6.9% and 25.0% in the 3% BSA group vs. 1.2-6.4% and 0-16.7% in the other groups, respectively. In experiment 2, we added 10% fetal bovine serum (FBS) to PZM-3 on day 0 of culture and observed the development rate of blastocysts per day of culture from days 0 to 5. The development rate of blastocysts was higher at 15.6% on day 4 than on any other day, and was significantly higher than on day 0 or day 1 (p<0.05). The development rate of hatched blastocysts was 26.7% on day 4, and was higher than on any other day. In experiment 3, we cultured IVF embryos with different fluid culture media, grouped as 1) PZM-3+0.3% BSA (day0-day7); 2) PZM-3+0.3% BSA${\rightarrow}$day-4) PZM-3+10% FBS; 3) PZM-3+0.3% BSA${\rightarrow}$PZM-3+0.3% BSA+(day-4) FBS 10%; and 4) PZM-3+0.3% BSA+10% FBS (day0-day7). The development rates of blastocysts and hatched blastocysts were 21.5% and 53.1% in group 3, respectively, which was significantly higher than group 4 with respect to blastocyst development (5.2%, p<0.05) but not hatched blastocysts (14.3%). The total cell number (TCN) of blastocysts in group 3 was higher at $37.8{\pm}16.1$ than the other groups at $16.8{\pm}4.4$ - $30.1{\pm}10.9$; however, this was not significantly different. The results of this study showed that PZM-3 containing 0.3% BSA and supplemented with FBS during the later stage of culture on day 4 resulted in better TCNs and an increased rate of hatched blastocysts.