• 제목/요약/키워드: Colloid

검색결과 428건 처리시간 0.029초

Synthesis of Zirconium Oxide Nanoballs Using Colloid-Imprinted Carbon and Their Electrical Properties

  • Kim, Chy Hyung
    • Transactions on Electrical and Electronic Materials
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    • 제16권2호
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    • pp.86-89
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    • 2015
  • Uniform ZrO2 nanoballs were synthesized at 700℃ using the inverse replication method through a colloid-imprinted carbon (CIC) template. The structural, dielectric, and conducting properties of the ZrO2 nanoballs were investigated and compared with those of ZrO2 film prepared by sol-gel method and powdered ZrO2 chemical. Both the monoclinic and cubic phases were found in the ZrO2 balls and film but the ZrO2 chemical showed a monoclinic phase, where the cubic structure is known to be formed at above 2,300℃. ZrO2 nanoballs showed the lower dielectric property of k = 21.2 at 1 MHz because the 8-coordinated cubic phase in the ZrO2 nanoball produced lower polarization than the polarization of the 7-coordinated monoclinic ZrO2 chemical (k = 23.6). The dielectric stability was maintained in each ZrO2 ball, film, and chemical under the applied forward and reverse voltage range (−5 to +5 V) at 1 MHz. The ionic conductivities were 7.86 × 10−8/Ω·cm for ZrO2 nanoballs, 3.29 × 10−8/Ω·cm for ZrO2 chemical, and 6.70 × 10−5/Ω·cm for the thickness of 1,053 nm ZrO2 film at room temperature with the electronic contribution being less than 0.006%.

$^{99m}Tc-tin$ colloid를 이용(利用)한 간(肝)스캔상(上) "Hot spot"로 나타난 상대정맥증후군(上大靜脈症候群) 1예(例) (The Hot Spot in Superior Vena Caval Obstruction Using $^{99m}Technetium$ tin Colloid)

  • 김병태;권기익;신영태;조경빈;이명철;조보연;고창순
    • 대한핵의학회지
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    • 제15권1호
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    • pp.45-49
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    • 1981
  • The hot spot on liver scan was demonstrated by many authors in various conditions such as SVC obstruction, Budd-Chiari syndrome, liver abscess, hemangioma of liver, hepatic venoocclusive diseases, IVC obstruction, and tricuspid insufficiency. And the appearance of hot spot in SVC obstruction is due to unsual collateral circulation. But there was no report of this hots pot on liver scan in our country. We have recently observed one patient with SVC obstruction who shows well-defined area of increased radioactivity between right and left lobe of liver on liver scan using $^{99m}Tc-tin$ colloid, and demonstrated collateral circulations with RI venography using $^{99m}Tc-O_4$. The injection site of radiocolloid was left antecubital vein. This hot spot did not appear when the radiocolloid was injected into right leg vein. We report here this hot spot on liver scan in SVC obstruction with review of some liter atures.

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폴리비닐알코올과 폴리비닐알코올모노티올이 폴리초산비닐 라텍스의 안정성에 미치는 영향 (Effect of Poly(vinyl alcohol) and Poly(vinyl alcohol) Mono Thiol on the Stability Properties of Poly(vinyl acetate) Latex)

  • 이서용;박이순
    • 폴리머
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    • 제24권5호
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    • pp.579-588
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    • 2000
  • 보호콜로이드에 따른 입체 안정제 (steric stabilizer)작용이 폴리초산비닐 (poly(vinyl acetate), PVAc) 라텍스의 안정성에 미치는 영향을 조사하였다. 보호콜로이드로서 중합도 1080, 검화도 78.4%인 반응성 poly(vinyl alcohol) mono thiol (PVALT)를 사용한 것이 중합도 1100, 검화도 81.6%인 poly(vinyl alcohol) (PVA)를 사용하는 것보다 PVAc 라텍스의 안정성이 양호하였으며, 반응성 PVALT의 첨가량이 증가할수록 PVAc 라텍스의 안정성은 향상되었다. PVAc 라텍스 입자의 표면 형태 변화는 투과전자 현미경으로 관찰하였다. 입자크기는 반응성 PVALT의 첨가량이 증가할수록 감소하였다. 결과적으로 에멀젼의 중합 시 PVA보다 반응성 PVALT를 사용하는 것이 PVAc 라텍스의 안정성이 양호함을 알 수 있었다. 이는 반응성 PVALT로 인해 PVAc 라텍스 입자계면에 PVA와의 화학 결합을 유도할 수 있는 다량의 티올 (thiol)기가 도입되어 PVAc와 반응성 PVALT간의 화학반응으로 인한 PVALT-b-PVAc 블록 공중합체가 생성됨에 기인하는 것으로 사료된다. 아울러 제타전위는 탄산나트륨의 농도가 증가할수록 감소하였다.

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