10 research outputs found
๊ฐ์๊ฒฝ์๋กํ ์์๋ก ํด์ฒด ํ ๋ฐ์๋ ์ค์ค์ํ๊ธฐ๋ฌผ์ ๋ถํผ๊ฐ์๋ฅผ ์ํ ์ ํด์ ์ผ ๊ณต์ ๊ฐ๋ฐ
ํ์๋
ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ๊ณต๊ณผ๋ํ ์๋์ง์์คํ
๊ณตํ๋ถ, 2019. 2. ์ฌํ์ง.ํ์ฌ, 454๊ธฐ์ ์์๋ ฅ ๋ฐ์ ์๊ฐ ์ ์ธ๊ณ์ ์ผ๋ก ์ด์ ์ค์ ์์ผ๋ฉฐ ์ ์ฒด ๋ฐ์ ๋์ ์ฝ 11%๋ฅผ ์ฐจ์งํ๊ณ ์๋ค. ์ด ์ค ์ฝ 66%์ ์์๋ ฅ ๋ฐ์ ์๋ 30๋
์ด์ ๊ฐ๋๋์์ผ๋ฉฐ, ์ด์ ๊ฐ์ ๋
ธํ์์ ์ ๋น์จ์ด ์์ผ๋ก ์ง์์ ์ผ๋ก ์ฆ๊ฐํ ๊ฒ์ผ๋ก ์์๋๋ค. ๊ตญ๋ด์ ๊ฒฝ์ฐ, ์ด๋ฏธ ๊ณ ๋ฆฌ 1ํธ๊ธฐ์ ์๊ตฌ์ ์ง๊ฐ ์ํ๋์์ผ๋ฉฐ 2030๋
์ ์ 7๊ธฐ์ ๊ฐ์๊ฒฝ์๋กํ ์์๋ก์ ์ค๊ณ์๋ช
์ด ๋ง๋ฃ๊ฐ ๋ ์์ ์ด๋ค. ์ด์ ๋ฐ๋ผ ์์๋ ฅ ๋ฐ์ ์ ํด์ฒด ์ค๋น ํ์์ฑ์ด ์ฆ๊ฐํ๊ณ ์์ผ๋ฉฐ ํด์ฒด์ ๋ฐ๋ผ ๋ฐ์ํ ์ค์ ์ค์ ๋ฐฉ์ฌ์ฑ ํ๊ธฐ๋ฌผ ๊ด๋ฆฌ๋ ์ค์ํด์ง๊ณ ์๋ค. ์ด ์ค, ์ค์ค์ ๊ธ์ ํ๊ธฐ๋ฌผ์ด ๋ฐ์ํ๋ ์์ ์ฝ 66ํค์ผ๋ก ์ฃผ๋ก ๋ฐฉ์ฌํ ๋
ธ๋ด ๊ตฌ์กฐ๋ฌผ๋ก ์ด๋ฃจ์ด์ ธ ์๋ค. ๋
ธ๋ด ๊ตฌ์กฐ๋ฌผ์ ์คํ
์ธ๋ฆฌ์ค๊ฐ์ผ๋ก ์ด๋ฃจ์ด์ ธ ์์ผ๋ฉฐ ๋
ธ์ฌ ์ฃผ๋ณ๋ถ๋ก์จ ๋์ ์ค์ฑ์์์ ์ฅ๊ธฐ๊ฐ ๋
ธ์ถ๋์ด ์๋ค. ์คํ
์ธ๋ฆฌ์ค๊ฐ์ด ๋ฐฉ์ฌํ๋จ์ผ๋ก์จ C14, Nb94, Ni59, Ni63 ๊ณผ ๊ฐ์ ์ฅ์๋ช
๋ฐฉ์ฌ์ฑ ํต์ข
๋ฐ Co60๊ณผ ๊ฐ์ ๋จ์๋ช
๋ฐฉ์ฌ์ฑ ํต์ข
์ด ๋ฐ์ํ๊ฒ ๋๋ค. ํ์ง๋ง ํํ ๊ท์ ์ ๋ฐฉ์ฌํ ๋
ธ๋ด ๊ตฌ์กฐ๋ฌผ๊ณผ ๊ฐ์ด ์ฅ์๋ช
๋ฐฉ์ฌ์ฑ ํต์ข
์ด ๋ค๋ ํฌํจ๋ ์ค์ค์ ๋ฐฉ์ฌ์ฑ ํ๊ธฐ๋ฌผ์ ๊ฒฝ์ฃผ ์ค์ ์ค์ ๋ฐฉ์ฌ์ฑ ํ๊ธฐ๋ฌผ ์ฒ๋ถ์ฅ์ ๋ฐฉ์ฌ๋ฅ ์ด๋ ๊ท์ ๊ธฐ์ค ํ๊ณ์ ์ํด ์ฒ๋ถ๋ ์ ์๋ค. ๋ฐ๋ผ์, ์ฐ๋ฆฌ๋๋ผ๋ฟ๋ง ์๋๋ผ ๋๋ค์์ ๊ตญ๊ฐ๋ค์ด ๊ด๋ จ์์ค์ ์์์ ์ฅ์์ ๋ณด๊ด ์ค์ด๋ฉฐ ๊ณ ์ค์ ๋ฐฉ์ฌ์ฑ ํ๊ธฐ๋ฌผ ํน์ ์ฌ์ฉํํต์ฐ๋ฃ ์ฒ๋ถ์ฅ์ ๊ฑด์ค์ ๊ธฐ๋ค๋ฆฌ๊ณ ์๋ ์ํฉ์ด๋ค. ์ด๋ฅผ ํด๊ฒฐํ๊ธฐ ์ํ ์ฅ์๋ช
๋ฐฉ์ฌ์ฑ ํต์ข
์ ํฌํจํ ์ค์ค์ ๊ธ์ ํ๊ธฐ๋ฌผ๋ค์ ์ ์ผ๊ธฐ์ ๊ฐ๋ฐ์ด ํ์ํ๋ค.
ORIGEN-2๋ฅผ ํ์ฉํ์ฌ ๊ฐ์๊ฒฝ์๋ก ๋
ธ๋ด ๊ตฌ์กฐ๋ฌผ์ด 32๋
์ ํจ์ ์ถ๋ ฅ๊ธฐ๊ฐ์ ๊ฐ์ ํ์ฌ ๋ชจ๋ธ๋งํ ๊ฒฐ๊ณผ, ๋๊ฐ๊ธฐ๊ฐ์ด 15๋
์ง๋ ๋ค ์ ํต์ข
๋ค์ ๋ฐฉ์ฌ๋ฅ ๋๋๋ C14(1.83E+06Bq/g), Nb94(2.88E+04Bq/g), Ni59(5.40E+06), Ni63(1.05E+07Bq/g), Co60(1.35E+09Bq/g)์ผ๋ก ์ค์ค์ ๋ฐฉ์ฌ์ฑ ํ๊ธฐ๋ฌผ๋ก ํ๊ฐ๋๋ค. ๊ตญ๋ด ๊ฐ์๊ฒฝ์๋กํ ์์๋ก ํด์ฒด ํ ๋์ฌ ์ค์ค์ ๋
ธ๋ด ๊ตฌ์กฐ๋ฌผ๋ค์ด ๋ชจ๋ ๊ฒฝ์ฃผ ์ค์ ์ค์ ๋ฐฉ์ฌ์ฑ ํ๊ธฐ๋ฌผ ์ฒ๋ถ์ฅ์ ์ฒ๋ถ๋๊ธฐ ์ํด ์๊ตฌ๋๋ ์ ์ผ๊ณ์๋ ๊ฐ๊ฐ 8.2, 259.1, 73.0, 94.7, 36.6์ด๋ค.
๋ณธ ๋
ผ๋ฌธ์์ ์ ์ํ๋ ์ ์ผ๊ณต์ ์ ๋ฐฉ์ฌํ ํต์ข
์ ์ฒด์ ์ ์ผ์ํฌ ์ ์์ผ๋ฉฐ, ์ด๋ก ์ ์ผ๋ก 2์ฐจํ๊ธฐ๋ฌผ ๋ฐ์๋์ด 0์ธ ์ฉ์ต์ผ ๊ธฐ๋ฐ ์ ํด์ ๋ จ์ด๋ค. ์ฉ์ต์ผ์ ๋ถํ๋ฌผ(LiF-KF)๋ณด๋ค ์ด์ ์จ๋๊ฐ ๋ฎ๊ณ ๋ถ์๋ฌธ์ ๊ฐ ์ ์ ์ผํ๋ฌผ(LiCl-KCl)์ ์ ํํ์๊ณ ํต์ข
๋ค ์ฌ์ด ํ์์ ์์ฐจ๋ฅผ ์ด์ฉํ์ฌ ์ฅ์๋ช
ํต์ข
๋ค์ ๋จ๊ธฐ๊ณ ์ฐํ๊ฒฝํฅ์ฑ์ด ํฐ Fe๊ณผ Cr์ ํ์ํ๋ ์คํ์ ์ํํ์๋ค.
์ ํด์ ๋ จ ์คํ ์ ์ฃผ์ ์์๋ค(Fe, Co, Ni, Cr)์ LiCl-KCl ์ฉ์ต์ผ ๋ด ์ฐํํ์ ๊ฑฐ๋์ ์์๋ณด๊ธฐ ์ํด ๊ฐ ์์๋ค์ ์ผํ๋ฌผ์ ๋
น์ธ ํ 500โ์์ ์ํ์ ์์ ๋ฅ๋ฒ์ ์ํํ์๋ค. Cr์ ์ ์ธํ ๋ชจ๋ ํต์ข
๋ค์ ํ ๊ฐ์ฉ์ ์ฐํํ์ํผํฌ ์์ ๋ณด์์ผ๋ฉฐ, ๋จ์ํ ๊ฑฐ๋์ ๋ณด์๋ค. Cr์ ๋ ์์ ์ฐํํ์ํผํฌ๋ฅผ ๋ณด์์ผ๋, Fe์ ์ฐํํผํฌ๊ฐ -0.2~-0.1V[vs. 1 wt. % Ag/AgCl] ์์ ๋ฐ์ํ๋ ๊ฒ์ผ๋ก ๋ณด์์ ๋, Cr2+์ Cr3+ ์ฌ์ด์ ์ฐํ๊ฑฐ๋์ ๋ฌด์ํ ์ ์์ ๊ฒ์ผ๋ก ํ๋จํ๋ค.
์ํ์ ์์ ๋ฅ๋ฒ์ ํตํด ๋์จ ๊ฒฐ๊ณผ๋ฅผ ํ ๋๋ก ๊ฐ ์์๋ณ Apparent reduction potential๊ณผ ์ฉ์ต์ผ ๋ด ํ์ฐ ๊ณ์๋ฅผ ํ๋ํ์๋ค. ๋ํ, Linear Polarization Method๋ฅผ ํตํด ๊ฐ ํต์ข
๋ค์ ๊ตํ ์ ๋ฅ ๋ฐ๋ ๋ฐ ์ ํ์ ๋ฌ๊ณ์๋ฅผ ํ๋ํจ์ผ๋ก์จ ๊ด๋ จ ์ฐ๊ตฌ๋ฅผ ์ํ ๋ฐ์ดํฐ๋ฒ ์ด์ค๋ฅผ ๊ตฌ์ถํ์๋ค. ๊ตฌ์ถ๋ ๋ฐ์ดํฐ๋ฒ ์ด์ค์ 1-D ์๊ฐ ์ข
์ ์ ๊ธฐํํ ๋ชจ๋ธ๋ง์ฝ๋ REFIN์ ํ์ฉํ์ฌ ์ ํด์ ๋ จ ๋ชจ๋ธ๋ง์ ์ํํจ์ผ๋ก์จ ์ ํด์ ๋ จ์ ํตํ ์ ์ผ๊ณ์ ํ๋ณด๊ฐ๋ฅ์ฑ์ ํ๊ฐํ์๋ค. ์ ํด์ ๋ จ์ ํตํด Nb, Co์ ๋ํ ์ ์ผ๊ณ์๋ ํ๋ณด๊ฐ๋ฅํ๋ค๋ ๊ฒ์ ๋ณด์์ผ๋ฉฐ, Ni์ ๊ฒฝ์ฐ 2๋ฒ์ ๋ฐ๋ณต๊ณผ์ ์ ๊ฑฐ์น๋ฉด ์ ์ผ๊ณ์๋ฅผ ๋ฌ์ฑํ ์ ์๋ค.
๋ชจ๋ธ๋ง ๊ฒฐ๊ณผ์ ๊ฒ์ฆ์ ์ํด ์ ํด์ ๋ จ ์คํ์ ์ํํ์๋ค. ์คํ ์กฐ๊ฑด์ LiCl-KCl-3 wt. % FeCl2 ์ฉ์ต์ผ์ ์ฌ์ฉํ์๊ณ , ์๊ทน์ ์คํ
์ธ๋ฆฌ์ค๊ฐ ๋ง๋๋ฅผ ์ฌ์ฉํ์๋ค. ์คํ ์ค ์๊ทน, ์๊ทน์์ ๋จ์ด์ ธ ๋์ฌ ์ ์๋ ๊ธ์๋ค์ ํ์ ํน์ ๊ธ์ ๋ฌผ์ง์ ์ํ ์ค์ผ ๋ฐฉ์ง๋ฅผ ์ํด ์ ๊ทน ์ฃผ๋ณ์ ์ฉ๊ธฐ๋ฅผ ์ค์นํ์๋ค. ์๊ทน์ ๊ฑธ๋ฆฌ๋ ์ ์๊ฐ -0.2V[vs. 1 wt. % Ag/AgCl], -0.2V[vs. 1 wt. % Ag/AgCl], -0.1V[vs. 1 wt. % Ag/AgCl], 0V[vs. 1 wt. % Ag/AgCl]๋ก ๋ค๋ฅด๊ฒ ์ฃผ์ด 3๋ฒ ์ํํ์๋ค. ์ ํด ์ ๋ จ ์
๋ด ์๊ทนํ๋ฉด, ์๊ทน ์ฉ๊ธฐ ๋ด๋ถ, ์๊ทน ์ฉ๊ธฐ ๋ด๋ถ, ์ฉ์ต์ผ๋ค์ ICP-MS ๋ถ์์ ์ํํ์์ผ๋ฉฐ, ์๊ทนํ๋ฉด์ ์ ์ฐฉ๋ฌผ์ ํ์ธํ๊ธฐ ์ํด XRD ๋ถ์์ ์ํํ์๋ค. ๋ถ์ ๊ฒฐ๊ณผ ์๊ทนํ๋ฉด์ Fe๊ฐ ๊ธ์์ํ๋ก ์ ์ฐฉ๋๋ ๊ฒ์ด ํ์ธ๋์์ผ๋ฉฐ, ์๊ทน ์ธ๊ฐ ์ ์๊ฐ ์ฆ๊ฐํ๋ฉด์ Co, Ni์ ์ ์ผ๊ณ์๊ฐ ๊ฐ์ํ๋ ๊ฒ์ ํ์ธ๋์๋ค. ์ด๋ ์๊ทน ์ธ๊ฐ ์ ์์ ์ฆ๊ฐ๋ก Fe๋ฟ๋ง์ด ์๋ Co, Ni์ ์ฐํ ํผํฌ๊ฐ ์ผ์ ๋ถ๋ถ ํฌํจ๋๋ฉด์ ์๊ทน์์ ๋
น์๋์ ์ ์ฐฉ์ด ๋ ๊ฒ์ผ๋ก ์์๋๋ค. ํ์ง๋ง 3๊ฐ์ง ์คํ ๋ชจ๋ ์ ํด์ ๋ จ ๊ณต์ ์ด 2๋ฒ ๋ฐ๋ณต ์ํ๋์์ ๋, ์๊ตฌ๋๋ ์ ์ผ๊ณ์๋ฅผ ๋ง์กฑ์ํฌ ์ ์๋ ๊ฒ์ผ๋ก ํ์ธ๋์๋ค.
์ค์ ๊ณต์ ๋ด์์ ํ๊ณ์ ๋ฅ์ ํ์ฐ์ธต ์ ์ด๋ฅผ ์ํด ํ์ ์ ๊ทน์ ์ฌ์ฉํ๋ค๋ ์ ์ ๊ณ ๋ คํ์ฌ ์
๋ด ์ฉ๊ธฐ๋ฅผ ์ค์นํ ๊ฒ์ด์๋ค. ํ์ง๋ง ์ ํด์ ๋ จ ์คํ ์ค ํ๊ณ์ ๋ฅ์ ํ์ฑ์ด๋ผ๋ ๋ฌธ์ ์ ์ ํ์ธํ ์ ์์๊ณ ์ด๋ฅผ ๋ณด์ํ๊ธฐ ์ํด CFX์ฝ๋๋ฅผ ํ์ฉํ์ฌ ์๋ก์ด ์
๋์์ธ์ ์ค๊ณํ์๋ค. ์
๋ด ์ถ๊ฐ์ ์ธ ์ฉ๊ธฐ์ ๋์์ธ์ ๋ฏธ์ธ ๋ค๊ณต์ฑ ๊ตฌ์กฐ๋ก ๋ชจ๋ธ๋งํ์ฌ ์ ์ฒด ๋ด ์
์ ๊ฑฐ๋ ํด์๊ณผ ์ ์ ๊ฐํ์ ๋ํ ์๋ฎฌ๋ ์ด์
์ ์ํํ์๋ค. ๋ฏธ์ธ ๋ค๊ณต์ฑ ์ฉ๊ธฐ๋ฅผ ํตํด ์ ์ ๊ฐํ๋ 2๋ฐฐ ์ด์์ ํจ์จ์ ๋ณด์์ผ๋ฉฐ, ํ์ ์ ๊ทน์ ์ํ ์ ์ฒด ๊ฑฐ๋์ ๋ฐ๋ฅธ ์
์์ ์๊ทน ์ฉ๊ธฐ ๋ด ์ดํ์ด ํจ์จ์ ์ผ๋ก ์ ์ด๋ ์ ์์์ ํ์ธํ์๋ค.
๋ณธ ๋
ผ๋ฌธ์ ์ฐ๊ตฌ๊ฒฐ๊ณผ๋ฅผ ํตํด ํ์ผ๋ฟ ๊ท๋ชจ์ ์ ํด์ ๋ จ๋ก๋ฅผ ์ ์ํ๋ค๋ฉด ๊ฒฝ์ ์ ์ผ๋ก 1320 ์ต์ ์ด์์ ํจ๊ณผ๋ฅผ ๋ํ๋ผ ๊ฒ์ผ๋ก ์์๋๋ค.Currently, 454 nuclear power plants are operating globally and account for about 11% of the total electric power generation. About 66% of these nuclear power plants have been in operation for more than 30 years, and the proportion of such old nuclear power plants is expected to continuously increase. In Korea, the Kori Unit #1 reactor has been decided to permanent shutdown, and 7 PWR reactors will reached the design life time before 2030. As a result, the need to prepare for the decommissioning of nuclear power plants is increasing, and the management of intermediate and low-level radioactive waste from decommissioning is also becoming important. Among them, the amount of the intermediate level metal waste from reactor internals periphery to reactor core is about 66 tons. The reactor internals are made of stainless steel and are exposed to high neutron flux for a long period. As the stainless steel is activated, long living activation products such as C14, Nb94, Ni59 and Ni63 and short living activation products such as Co60 are generated. However, according to the current regulations, intermediate level radioactive wastes containing a large amount of long living radionuclides can not be disposed of due to the total activity limits of Gyeongju repository. Therefore, most of the countries as well as Korea kept them in the interim storage on site and waiting for the construction of high-level radioactive waste or spent nuclear fuel repository. In order to solve this problem, it is necessary to develop decontamination technology for long living intermediate level wastes.
Based on ORIGEN-2 modeling with some assumptions, pressurized water reactor internals were modeled. The radioactivity of C14, Nb94, Ni59, Ni63 and Co60 were 1.83E+06Bq/g, 2.88E+04Bq/g, 5.40E+06Bq/g, 1.05E+07Bq/g, 1.35E+09Bq/g, respectively. The decontamination factors required for disposal of all reactor internals from 20 units are 8.2, 259.1, 73.0, 94.7, and 36.6, respectively.
In this paper, electrorefining process that takes good advantage of theoretically very low secondary waste generation was suggested for decontamination process. LiCl-KCl eutectic salt, which has lower operating temperature than fluoride salt (LiF-KF) and has less corrosion problem, was used as electrolyte. Approach for electrorefining is recovering Fe and Cr with high tendency to oxidation by leaving long-living nuclides using standard potential difference between them.
In order to investigate the behavior of the major elements (Fe, Co, Ni, Cr) in the LiCl-KCl, cyclic voltammetry at 500ยฐC was performed. All nuclides except for Cr showed a single pair of redox peak. Cr showed two pairs of redox peaks, but the oxidation peak of Fe was -0.2 ~ -0.1V [vs. 1 wt. % Ag/AgCl]. The oxidation behavior between Cr2+ and Cr3+ was negligible in that region. Apparent reduction potentials and diffusion coefficients in molten salt were obtained based on the results of cyclic voltammetry. In addition, a database for related studies was constructed by acquiring exchange current density and charge transfer coefficient of each nuclide through Linear Polarization Method. The achievability of the decontamination factors through electrorefining was evaluated by conducting REFIN modeling, 1-D time dependent simulation code. It showed that decontamination factors for Nb and Co can be achieved through electrorefining. In case of Ni, it is possible to achieve decontamination factor by 2 successive electrorefining.
Electrorefining experiments were performed to verify the modeling results. LiCl-KCl-3 wt. % FeCl2 was used as electrolyte, and a type 304 stainless steel rod was used as anode. During the experiment, baskets were installed around the anode to recover the metals that could come off from the anode and the cathode. The applied potential on anode were -0.2V[vs. 1 wt. % Ag/AgCl], -0.1V[vs. 1 wt. % Ag / AgCl], 0V[vs. 1 wt. % Ag/AgCl]. After electrorefining, the cathode surface, inside the baskets and bulk salts were analyzed by ICP-MS and XRD analysis was performed to confirm the deposition on cathode. As a result, it was confirmed that Fe was electrodeposited on the surface of the cathode and the decontamination factors of Co and Ni was decreased as the applied potential on anode was increased. However, in all three experiments, it was confirmed that the required decontamination factor can be satisfied when electrorefining process is repeated twice.
However, in the lab-scale electrorefining experiments, the problem of the formation of the limiting current was confirmed and the new cell design was designed using the CFX code to overcome the issues. The design of new baskets in the cell was modeled as a porous structure, and the particle tracking and the IR drop modeling were performed. The IR drop between anode and cathode was more than 2 times greater than that of the non-porous baskets.
These findings suggest that if a pilot-scale electrorefiner is manufactured, it would result in reduction of 132.6 billion KRW economically.Contents
Chapter 1 Introduction 1
1.1 Background 1
1.2 Problem Statement 4
Chapter 2 Literature Review 10
2.1 Electrochemistry of Decontamination 10
2.2 Electrochemistry Modeling Code 14
Chapter 3 Research Goal and Approach 16
3.1 Research Goal 16
3.2 Research Approach 16
Chapter 4 Decontamination Requirements for Activated Intermediate Level Waste 19
4.1 Inventory Analysis of PWR Internals 19
4.2 Calculation of Decontamination Factor (DF) 23
4.3 Feasibility of Decontamination 24
Chapter 5 Electrorefining Experiments of Stainless Steel 26
5.1 Experimental Setup of Cyclic Voltammetry 26
5.2 Cyclic Voltammetry of Fe, Co, Ni and Cr 29
5.3 Exchange Current Density Determination by Linear Polarization Method 36
5.4 1-D Electrorefining Modeling 42
5.5 Experimental Setup of Electrorefining 45
5.6 Electrorefining Results of Stainless Steel 48
Chapter 6 Pilot-Scale Conceptual Design 56
6.1 Overall Pyrochemical Decontamination Process Flowsheet 56
6.2 Issues for Cell Design 58
6.3 Unit Cell Design 62
6.4 Cost Benefit Analysis 63
Chapter 7 Conclusions and Future Work 65
7.1 Conclusions 65
7.2 Future Work 66
Appendix 68
Bibliography 74
Abstract 76Maste
The effect of blockade of the vasa vasorum upon cholesterol-induced atherosclerosis in rabbits
์๊ณผ๋ํ/๋ฐ์ฌ[ํ๊ธ]
The Effect of blockade of the Vasa Vasorum upon Cholesterol-induced Atherosclerosis
in Rabbits
by Chung Ho Huh, M.D,
Department of Pathology Yonsei University College of Medicine, Seoul, Korea
Directed by Professors: Dong Sik Kim, M.D., Kwang sik Min, M.D.
Introduction
since the vasa vasorum furnish most of the oxygen and nutrients for the arterial
wall, many investigators consider them to have an important role in the genesis of
degenerative disease of the arteries (Winternitz et al. 1938, Wartman 1938, 1955).
Among the degenerative disease of the arteries, the most serious and important
one is atherosclerosis. Atherosclerosis has been produced experimentally by the
excessive feeding of cholesterol (Duff 1935, Jobling and Meeker 1936, Duff and
McMillan 1951). Hypercholesterolemia is regarded as a prime factor in the
development of atherosclerosis. However, previous investigations by the authors
(Huh and Kim 1965, and chang 1965), as well as other reports in the literature,
strongly indicate that many factors other than increased lipids in the blood also
play an important role in atherogenesis (Wartman 1955).
These factors include local vascular wall changes and such as degeneration of the
media, intimal hyperplasia, local anoxia, and local alteration of hemodynamics,
etc.
Local injuries of the vascular wall have been induced by various methods;
injection of bacterial toxins or chemical agents, irradiation, crushing injuries,
freezing and by electric cauterization. Any type of local alteration of the
vascular wall enhances the development of atheroma formation. However, the
mechanism by which local alterations accelerate atheroma formation has not been
elaborated.
The present investigation was undertaken to investigate the normal distribution
of the vasa vasorum in the aorta of rabbit, effect of the blockade of the vasa
vasorum on the normal aortic wall, and finally the influence of the blockade of the
vasa vasorum upon cholesterol-induced atherosclerosis in rabbits.
Materials and Methods
Albino rabbits, around 1.8kg of body weight, were divided into four groups and
treated as follows.
Group โ
consisted of 5 normal rabbits which were subjected to the demonstration
of the aortic vasa vasorum using the lead acetate and potassium dichromate
impregnation method of williams (1948) to study the normal distribution of the vasa
vasorum.
Group โ
ก of 14 rabbits were subjected to blockade of the aortic vasa vasorum to
investigate the effect of the blockade of vasa vasorum on the normal aorta.
Group โ
ข of 5 rabbits were fed excessive amounts of cholesterol to induce
atherosclerosis.
Group โ
ฃ of 20 rabbits were fed an excessive amount of cholesterol after blockade
of the vasa vasorum to study the effect of the blockade of vasa vasorum upon
cholesterol-induced atherosclerosis.
The blockade of vasa vasrum was achieved by stripping off the adventitia of the
abdominal aorta between the renal arteries and the iliac bifurcation.
Then the stripped segment of the aorta was wrapped with polyethylene tubing to
prevent the formation of new vasa vasorum from the surrounding tissue. The
operation was performed under ether anesthesia with aseptic precautions, and
0.25Gm. of penstreptomycin was given for 3 days to prevent postoperative infection.
All animals were fed with a basic diet of a bean-curd residue, 200 Gms. per day
per animal. Cholesterol, mixed with a small amount of been-curd residue, was given
in a fasting state (1.5 Gm. per animal per day).
Serum total cholesterol determination was made once a month. Animals in group โ
ก
and โ
ฃ were killed at set intervals to make serial studies on the effect of
blockade of the vasa vasorum after the operation. The longest observation period
lasted 80 days.
At the necropsy, a section from the heart, kidneys, adrenals, liver, and thyroid
was taken, and sections were taken from the ascending, arch, thoracic, abdominal
and operative site from the aorta. All sections were embedded in paraffin after
fixation with 4% neutral formalin. Microsections were cut at 5-6 ฮผ. thickness.
Hematoxylin-esoin, Verhoeff Van Gieson, and colloidal-iron stains were applied to
all aortic sections and hematoxylin-eosin stain alone to the sections from other
organs.
Results and Summary
All animals fed with cholesterol (group โ
ข and โ
ฃ) showed marked and rapid
elevation of serum cholesterol concentration during the first month after the
beginning of the experiment. However, thereafter, continuous feeding of cholesterol
raised the serum cholesterol level more slowly and to a lesser degree than during
the first month. There was no statistical difference between the serum cholesterol
levels in group โ
ข and โ
ฃ. The elevation of serum cholesterol in both groups was
mainly due to the increase in the ester fraction.
The distribution of the vasa vasorum in the aorta of nomal rabbits was confined
to the outer adventitia with short ramifications into the inner adventitia. No case
showed penetration of the vasa vasorum into the media. No direct opening from the
intima was noted.
Blockade of the vasa vasorum caused a complete ischemic necrosis of the entire
thickness of the aortic segment and an acute inflammatory reaction followed by
calcification. Finally the aortic wall was reestablisbed by a newly formed
hyperplastic fibromuscular intima which later resulted in the narrowing of the
lumen.
After 80 days rabbits fed cholesterol alone showed a relatively mild degree of
atheroma formation at the ascending and arch portions of the aorta. The thoracic
and abdominal portions of the aorta showed a minimal amount of atheroma formation
around the ostia of the arterial branchings from the aorta. However, at all parts
of the aorta as well as in the coronary arteries, atheroma formation in the animals
fed with cholesterol after the blockade of the vasa vasorum was greater than that
of cholesterol fed animals which did not have blockade of the vasa vasorum.
Accentuated atheroma formation was noted in the segment of the aorta where the
vasa vasorum were blocked. Atheroma at the site of the vasa vasorum blockade showed
of proliferative intimal thickening, medial necrosis, medial calcification, and
lipid deposition in the thickened intima and degenerated media, simulating the
atheroma seen in the human aorta.
The enhancement of atheroma formation at the site of vasa vasroum blockade was
considered due to the accelerating effect of lipid deposition followed by a
fibromuscular proliferation in the intima. Also the blockade of venous vasa vasorum
impaired lipid clearance from the aortic wall. The increase of atheroma formation
in the remaining areas of the aorta was probably due to increased blood pressure
secondary to localized stricture of the aorta at the site at which the vasa vasorum
was blocked.
[์๋ฌธ]
Introduction
since the vasa vasorum furnish most of the oxygen and nutrients for the arterial wall, many investigators consider them to have an important role in the genesis of degenerative disease of the arteries (Winternitz et al. 1938, Wartman 1938, 1955).
Among the degenerative disease of the arteries, the most serious and important one is atherosclerosis. Atherosclerosis has been produced experimentally by the excessive feeding of cholesterol (Duff 1935, Jobling and Meeker 1936, Duff and
McMillan 1951). Hypercholesterolemia is regarded as a prime factor in the development of atherosclerosis. However, previous investigations by the authors (Huh and Kim 1965, and chang 1965), as well as other reports in the literature, strongly indicate that many factors other than increased lipids in the blood also
play an important role in atherogenesis (Wartman 1955).
These factors include local vascular wall changes and such as degeneration of the media, intimal hyperplasia, local anoxia, and local alteration of hemodynamics, etc.
Local injuries of the vascular wall have been induced by various methods; injection of bacterial toxins or chemical agents, irradiation, crushing injuries, freezing and by electric cauterization. Any type of local alteration of the vascular wall enhances the development of atheroma formation. However, the
mechanism by which local alterations accelerate atheroma formation has not been elaborated.
The present investigation was undertaken to investigate the normal distribution of the vasa vasorum in the aorta of rabbit, effect of the blockade of the vasa vasorum on the normal aortic wall, and finally the influence of the blockade of the vasa vasorum upon cholesterol-induced atherosclerosis in rabbits.
Materials and Methods
Albino rabbits, around 1.8kg of body weight, were divided into four groups and treated as follows.
Group โ
consisted of 5 normal rabbits which were subjected to the demonstration of the aortic vasa vasorum using the lead acetate and potassium dichromate impregnation method of williams (1948) to study the normal distribution of the vasa
vasorum.
Group โ
ก of 14 rabbits were subjected to blockade of the aortic vasa vasorum to investigate the effect of the blockade of vasa vasorum on the normal aorta.
Group โ
ข of 5 rabbits were fed excessive amounts of cholesterol to induce atherosclerosis.
Group โ
ฃ of 20 rabbits were fed an excessive amount of cholesterol after blockade of the vasa vasorum to study the effect of the blockade of vasa vasorum upon cholesterol-induced atherosclerosis.
The blockade of vasa vasrum was achieved by stripping off the adventitia of the abdominal aorta between the renal arteries and the iliac bifurcation.
Then the stripped segment of the aorta was wrapped with polyethylene tubing to prevent the formation of new vasa vasorum from the surrounding tissue. The operation was performed under ether anesthesia with aseptic precautions, and 0.25Gm. of penstreptomycin was given for 3 days to prevent postoperative infection.
All animals were fed with a basic diet of a bean-curd residue, 200 Gms. per day per animal. Cholesterol, mixed with a small amount of been-curd residue, was given in a fasting state (1.5 Gm. per animal per day).
Serum total cholesterol determination was made once a month. Animals in group โ
ก and โ
ฃ were killed at set intervals to make serial studies on the effect of blockade of the vasa vasorum after the operation. The longest observation period lasted 80 days.
At the necropsy, a section from the heart, kidneys, adrenals, liver, and thyroid was taken, and sections were taken from the ascending, arch, thoracic, abdominal and operative site from the aorta. All sections were embedded in paraffin after fixation with 4% neutral formalin. Microsections were cut at 5-6 ฮผ. thickness.
Hematoxylin-esoin, Verhoeff Van Gieson, and colloidal-iron stains were applied to all aortic sections and hematoxylin-eosin stain alone to the sections from other organs.
Results and Summary
All animals fed with cholesterol (group โ
ข and โ
ฃ) showed marked and rapid elevation of serum cholesterol concentration during the first month after the beginning of the experiment. However, thereafter, continuous feeding of cholesterol raised the serum cholesterol level more slowly and to a lesser degree than during the first month. There was no statistical difference between the serum cholesterol levels in group โ
ข and โ
ฃ. The elevation of serum cholesterol in both groups was mainly due to the increase in the ester fraction.
The distribution of the vasa vasorum in the aorta of nomal rabbits was confined to the outer adventitia with short ramifications into the inner adventitia. No case showed penetration of the vasa vasorum into the media. No direct opening from the intima was noted.
Blockade of the vasa vasorum caused a complete ischemic necrosis of the entire thickness of the aortic segment and an acute inflammatory reaction followed by calcification. Finally the aortic wall was reestablisbed by a newly formed hyperplastic fibromuscular intima which later resulted in the narrowing of the
lumen.
After 80 days rabbits fed cholesterol alone showed a relatively mild degree of atheroma formation at the ascending and arch portions of the aorta. The thoracic and abdominal portions of the aorta showed a minimal amount of atheroma formation around the ostia of the arterial branchings from the aorta. However, at all parts of the aorta as well as in the coronary arteries, atheroma formation in the animals fed with cholesterol after the blockade of the vasa vasorum was greater than that of cholesterol fed animals which did not have blockade of the vasa vasorum.
Accentuated atheroma formation was noted in the segment of the aorta where the vasa vasorum were blocked. Atheroma at the site of the vasa vasorum blockade showed of proliferative intimal thickening, medial necrosis, medial calcification, and lipid deposition in the thickened intima and degenerated media, simulating the atheroma seen in the human aorta.
The enhancement of atheroma formation at the site of vasa vasroum blockade was considered due to the accelerating effect of lipid deposition followed by a fibromuscular proliferation in the intima. Also the blockade of venous vasa vasorum impaired lipid clearance from the aortic wall. The increase of atheroma formation in the remaining areas of the aorta was probably due to increased blood pressure secondary to localized stricture of the aorta at the site at which the vasa vasorum was blocked.restrictio
์ฒญ๊ณ์ฒ ๋ณต๊ตฌ์ ๋ฐ๋ฅธ ์ฃผ๋ณ๊ฑด๋ฌผ์ ๋๋ฐฉ๋ถํ ์ ๊ฐํจ๊ณผ์ ๊ดํ ์ฐ๊ตฌ (Analysis of Restored Choengye stream effect on reducing the building cooling loads)
Analysis of protein sequences in each domain of G-protein-coupled receptors based on pattern driven approaches
Maste