• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.1-33
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• 1997

The objective of this study was to analyze the in vitro and in vivo corrosion products of low and high copper amalgams. The four different types of amalgam alloy used in this study were Fine cut, Caulk spherical, Dispersalloy, and Tytin. After each amalgam alloy and Hg were triturated according to the directions of the manufacturer by means of the mechanical amalgamator(Amalgam mixer. Shinhung Co. Korea), the triturated mass was inserted into a cylindrical metal mold which was 12mm in diameter and 10mm in height. The mass was condensed by 150Kg/cm compressive force. The specimen was removed from the mold and aged at room temperature for about seven days. The standard surface preparation was routinely carried out by emery paper polishing under running water. In vitro amalgam specimens were potentiostatically polarized ten times in a normal saline solution at $37^{\circ}C$(potentiostat : HA-301. Hukuto Denko Corp. Japan). Each specimen was subjected to anodic polarization scan within the potential range -1700mV to+400mV(SCE). After corrosion tests, anodic polarization curves and corrosion potentials were obtained. The amount of component elements dissolved from amalgams into solution was measured three times by ICP AES(Inductive Coupled Plasma Atomic Emission Spectrometry: Plasma 40. Perkim Elmer Co. U.S.A.). The four different types of amalgam were filled in occlusal and buccal class I cavities of four human 3rd molars. After about five years the restorations were carefully removed after tooth extraction to preserve the structural details including the deteriorated margins. The occlusal surface, amalgam-tooth interface and the fractured surface of in vivo amalgam corrosion products were analyzed. In vivo and in vitro amalgam specimens were examined and analyzed metallographically by SEM(Scanning Electron Microscope: JSM 840. Jeol Co. Japan) and EDAX(Energy Dispersive Micro X-ray Analyser: JSM 840. Jeol Co. Japan). 1. The following results are obtained from in vitro corrosion tests. 1) Corrosion potentials of all amalgams became more noble after ten times passing through the in vitro corrosion test compared to first time. 2) After times through the test, released Cu concentration in saline solution was almost equal but highest in Fine cut. Ag and Hg ion concentration was highest in Caulk spherical and Sn was highest in Dispersalloy. 3) Analyses of surface corrosion products in vitro reveal the following results. a)The corroded surface of Caulk spherical has Na-Sn-Cl containing clusters of $5{\mu}m$ needle-like crystals and oval shapes of Sn-Cl phase, polyhedral Sn oxide phase. b)In Fine cut, there appeared to be a large Sn containing phase, surrounded by many Cu-Sn phases of $1{\mu}m$ granular shapes. c)Dispersalloy was covered by a thick reticular layer which contained Zn-Cl phase. d)In Tytin, a very thin, corroded layer had formed with irregularly growing Sn-Cl phases that looked like a stack of plates. 2. The following results are obtained by an analysis of in vivo amalgam corrosion products. 1) Occlusal surfaces of all amalgams were covered by thick amorphous layers containing Ca-P elements which were abraded by occlusal force. 2) In tooth-amalgam interface, Ca-P containing products were examined in all amalgams but were most clearly seen in low copper amalgams. 3) Sn oxide appeared as a polyhedral shape in internal space in Caulk spherical and Fine cut. 4) Apical pyramidal shaped Sn oxide and curved plate-like Sn-Cl phases resulted in Dispersalloy. 5) In Tytin, Sn oxide and Sn hydroxide were not seen but polyhedral Ag-Hg phase crystal appeared in internal space which assumed a ${\beta}_l$ phase.

• 대한약리학회지
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• 제19권1호
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• pp.37-60
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• 1983

The uterus receives adrenergic terminals from the mesenteric ganglia and considerably large amount of catecholamines have been shown to be contained in this organ. On the other hand, the activities of epinephrine, norepinephrine or adrenergic nerve on uterine motility is so complicated that many controversial results have been reporter. Recently, a large number of reports concerning the changes of uterine catecholamines content have appeared, but little is known about the role of uterine catecholamines in their activities on uterine motility. The present experiments were undertaken to determine the significance of the intrinsic uterine catecholamines in the physiology of uterus. Female albino rabbits weighing approximately 2 kg were employed in this experiment. uterine strip3 were prepared and suspended in a constant temperature $bath(38^{\circ}C)$ containing 100 ml of Locke's solution aerated with 95% oxygen and 5% carbon dioxide. Spontaneous motility was recorded on a smoked drum with an isotonic lever. The catecholamines concentration of the uterus was determined according to the Procedure described of Shore and Olin (1958). Human uterus obtained from patients was also used to determine the catecholam ines content of myometrium. Followings are summarized results. 1) On the non-pregnant rabbit uterine strips, epinephrine and norepinephrine significantly elevated the tonus and stimulated the spontaneous motility. Pretreatment with dichloroisoproterenol(DCI), an adrenergic beta-receptor blocker, enhanced the stimulatory activity of epinephrine or norepinephrine. On the other hand, pretreatment with dibenamine, an adrenergic alpha-receptor blocker, rendered the uterine muscle to exhibit inhibition after the administration of epinephrine or norepinephrine. Following the treatment with both DCI and dibenamine, epinephrine or norepinephrine produced no appreciable effects on the spontaneous motility of the uterus. These results suggest there exist both alpha and beta-adrenergic receptors in the uterine muscle and the response to epinephrine of the former is predominant over that of latter in the non-pregnant uterus of rabbits. The total catecholamines concentration of the non-pregnant uterus was $351\;m{\mu}g/g$ and the fractional concentrations of epinephrine and norepinephrine were $125\;m{\mu}g/g(35.7%)$ and $226\;m{\mu}g/g$ respectively. It is interesting to note that the catecholamines content of uterus was characterized by a high fractional corcentration of epinephrine relative to norepinephrine. 2) On the pregnant rabbit uterine strips, the effects of epinephrine and norepinephrine varied according to the period of pregnancy. The response to epinephrine of adrenergic beta receptor of uterus increased during pregnancy, and the effect of catecholamine was inhibitory in the early pregnancy but became stimulatory as the pregnancy progressed. This stimulating action on the uterine motility was found to occur through the action of norepinephrine. The uterine catecholamines concentration was markedly reduced during pregnancy. The catecholamines concentration was started to decrease in the early pregnancy, reached the lowest level in the mid-pregnancy and then started to increaae again in the late pregnancy when the total catecholamines content became the highest level of all. This increase of catefholamines in late pregnancy was chiefly due to the increase of norepinephrine. These results suggest that the uterine motility may be related to the catecholamines content, especially norepinephrine content in the uterus. 3) Bilateral oophorectomy of rabbits results in a marked shrink of the uterus in size. The spontaneous motility of the uterine segment of these animals was very weak and irregular. Norepinephrine produced inhibitory effect, whereas epinephrine was stimulatory or inhibitory effect on the uterine segment. The total catecholamines tontent in whole uterus was markedly reduced. The injection of estrogen into the oophorectornized rabbit increased the weight of uterus to approximately three times of that of oophorectornized animal. The apontaneous motility and the response to epinephrine and norepinephrine of the uterine segment were greatly enhanced. Both epinephrine and norepinephrine produced a marked stimulatory effects of the uterine motility. The uterine content of catecholamines, particularly epinephrine, was markedly increased. The injection of progesterone into the oophorectornized rabbit increaeed the weight of uterus to approximately 2.5 times of that of eophorectornized animal. The spontaneous motility of the uterine segment was weak and irregular. Epinephrine produced stimulatory effect at high concentrations but norepinephrine always prcdnced inhibitory effect on the uterine segment. The uterine content of catecholamines, particularly of norepinephrine, was markedly reduced. These results suggested that ovarian hormones play an important role not only on the growth and spontaneous norepinephrine of uterus but also on the catecholamines content and responee to epinephrine and norepinephrine of the uterus. 4) The intraperitoneal injection of reserpine(3 mg/kg) into the non-pregnant, pregnant and oophorectornieed rabbits markedly decreased the uterine content of catecholamines, particularly of the norepinephrine. The stimulatory response to epinephrine and. norepinephrine of the uterine segment of these reserpinized ratbits was markedly reduced whereas the inhibitory response to these catecholamines was enhanced. This finding further support the close relationship between the uterine catecholamines content and uterine response to epineptrire and norepinephrine. 5) In the human uterus, the concentration of epinephrine was actrally greater than that of norepinephrine and it was significantly greater during the proliferative phase of the menstrtal cycle. In the human pregnant uterus, the concentrations of toth epinephrine and ncrefinephrine were markedly reduced and showed about 45 percent rednction after 6-8 weeks of ectopic Pregnancy. At full term ana during labor, the concentrations of epinephrine and norepinephrine at placental sites were less than those found in the non-pregnant group. Of interest was the finding that the norepinephrine concentration of uterus from toxemic patients was two and half times higher than that of lower uterine segment of the nontoxemic pregnant individuals. Also the epinephrine concentraticn was slightly increaeed.

• 공업화학
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• 제17권3호
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• pp.235-242
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• 2006

Liquid phase alkylation of biphenyl (BP) was studied over large pore zeolites. Selective formation of the least bulky products, 4,4'-diisopropylbiphenyl (4,4'-DIPB) occurred only in the isopropylation of BP over some large pore molecular sieves. H-mordenites (MOR) gave the highest selectivity among them. The dealumination of MOR enhanced catalytic activity and the selectivity of 4,4'-DIPB because of the decrease of coke-deposition. Non-selective catalysis occurs on external acid sites over MOR with the low $SiO_2/Al_2O_3$ ratio because severe coke-deposition deactivates the acid sites inside the pores by blocking pore openings. The selectivity of DIPB isomers was changed with reaction temperature. Selective formation of 4,4'-DIPB was observed at moderate temperatures such as $250^{\circ}C$, whereas the decrease of the selectivity of 4,4'-DIPB occurred at higher temperatures as $300^{\circ}C$. However, 4,4'-DIPB was almost exclusive isomer in the encapsulated DIPB isomers inside the pores even at high temperatures. These decreases of the selectivity of 4,4'-DIPB are due to the isomerization of 4,4'-DIPB on the external acid sites. Some 12-membered molecular sieves, such as SSZ-24, MAPO-5 (M:Mg, Zn, Si), SSZ-31, and ZSM-12, which have straight channels, gave 4,4'-DIPB with moderate to high selectivity; however; SSZ-55, SSZ-42, and MAPO-36 (M: Mg, Zn) gave lower selectivity because of cages in 12-membered one dimensional channels. Three dimensional H-Y and Beta zeolites also yield 4,4'-DIPB in low yield because of their wide circumstances for the isopropylation of BP. The increasing the size of alkylating agent enhanced the shape-selective alkylaiton even for the zeolites, such as UTD-1. The ethylation of BP to ethylbiphenyls (EBPs) and diethylbiphenyls (DEBPs) over MOR was non-selective. The ethylation of BP to EBPs was controlled kinetically. However, there was difference in reactivity of EBPs and DEBPs for their further ethylation. 4-EBP was ethylated preferentially among the isomers, although the formation of 4,4'-DEBP was less selective. The least bulky 4-EBP and 4,4'-DEBP have the highest reactivity among EBPs and DEBPs for the ethylation to polyethylbiphenyls (PEBPs). These results show that the environments of MOR pores are too loose for shape selective formation of the least bulky isomers, 4-EBP and 4,4'-DEBP in the ethylation of BP, and that MOR pores have enough space for the further ethylation of 4,4'-DEBP.

• 폴리머
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• 제30권6호
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• pp.498-504
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• 2006

물을 반응매체로 하고 스티렌을 단량체로 하는 현탁중합법을 이용하여 입경이 $1{\sim}20{\mu}m$에 이르는 입자를 합성하고자 시도하였다. 소수성 실리카를 안정제로, azobisisobutyronitrile(AIBN)을 개시제로 선택하였다. 반응은 65에서 $95^{\circ}C$ 사이의 선택된 온도에서 진행하였다. 안정제의 농도는 물에 대하여 0.17 wt%에서 3.33 wt%까지 변화시켰으며, 개시제는 단량체에 대하여 0.13 wt%에서 6.0 wt%까지 변화시켰다. 소수성 실리카의 수용액 내의 분산은 정확한 pH 조절을 통하여 이루어졌으며, pH 10에서 최적의 분산을 보였다. 안정제의 농도를 증가하는 경우 초기에는 평균입경이 감소하다 안정제의 농도가 1.67 wt%에서 최소 평균입경을 나타낸 후 증가하였다. 이는 과다한 안정제의 농도로 인한 반응매체 내에서의 이차반응과 이로 인한 입자간의 응집에 기인하는 것으로 사료된다. 안정제의 농도 증가에 따른 분자량은 안정제의 농도가 0.13 wt%에서 1.00 wt%의 사이에서는 일정하였으나, 안정제의 농도가 1.67 wt%를 초과하며 증가하였다. 이러한 분자량의 변화는 과다한 안정제로 인한 개시제의 활성 및 효율 저하, 그리고 반응매체 내에서의 이차반응에 그 원인이 있는 것으로 사료된다. 개시제의 농도 증가 및/혹은 반응온도의 증가는 반응속도와 입경을 증가시켰다. 그 결과, 소수성 실리카를 안정제로 하는 현탁중합반응에서 안정제의 농도, 개시제의 농도, PH 그리고 반응온도의 조절을 통하여 평균입경이 $1{\sim}20{\mu}m$ 영역에 포함되는 구형의 폴리스티렌 입자를 합성할 수 있다는 사실을 확인하였다.제를 일으키지 않도록 주의를 기울여야 한다.s}20cm$에 대해 $0.941{\pm}0.008,\;1.032{\pm}0.004,\;1.049{\pm}0.014$이다. 치료 계획용 시스템과 수 계산에 의한 MU값의 계산 비교결과 7개 기관의 값이 허용오차 범위를 벗어났다. 쐐기를 제외한 8가지 조건에서 계산된 평균 MU값들은 SAD 조건으로 출력 교정된 장비가 SSD 조건으로 교정된 장비에 비해 6 MV 광자선은 3 MU, 10 MV 광자선은 5 MU 정도 더 높았다. 쐐기를 사용할 경우 MU값은 Varian사 장비와 Siemens사의 장비에 따라 다르고 동일 각의 쐐기를 사용할 경우 Siemens사의 쐐기를 사용할 때 MU값이 크다. 결론: 수집된 광자선 빔 데이터를 분석하여 빔데이터의 정확성과 치료계획용 시스템의 계산 정확성을 대략적으로 점검 할 수 있는 기준 값을 제시하였다.동결이 요구되며 본 연구에서 이용된 OPS 동결 방법이 폭넓게 활용될 것으로 사료된다.며 이 때가 최상의 교배 적기로 사료되며, 혈장 progesterone농도가 4.0 ng/ml 이상으로 증가한 날(Bay 0)을 기준으로 하였을 때부터 CI는 혈장 estradiol-$17{\beta}$ peak 후 1일째인 최고치를 나타내었고, CI peak 후 1일째인 Day 0에 혈장 progesterone 농도가 최초로 4.0 ng/ml 이상으로 증가하여 CI가 90% 이상으로 지속된 시기가 최상의 교배 적기임이 확인되었다. 따라서 혈장 progesterone농도 측정으로 정확한 배란 시기 및 교배 적기를 판정할 수 있으나, 시설비가 저렴하고 검사 방법이 간단한 질 세포 검사가 Shih-tzu 견에서 발정 주기, 교배