• The Korean Journal of Physiology and Pharmacology
• /
• 제3권4호
• /
• pp.393-404
• /
• 1999

We have reported that hypoxia stimulates EDRF(s) release from endothelial cells and the release may be augmented by previous hypoxia. As a mechanism, it was hypothesized that reoxygenation can stimulate EDRF(s) release from endothelial cells and we tested the hypothesis via bioassay experiment. In the bioassay experiment, rabbit aorta with endothelium was used as EDRF donor vessel and rabbit carotid artery without endothelium as a bioassay test ring. The test ring was contracted by prostaglandin $F_{2a}\;(3{\times}10^{-6}\;M)$ which was added to the solution perfusing through the aorta. Hypoxia was evoked by switching the solution aerated with 95% $O_2/5%\;CO_2$ mixed gas to one aerated with 95% $O_2/5%\;CO_2$ mixed gas. Hypoxia/reoxygenation were interexchanged at intervals of 2 minutes (intermittent hypoxia). In some experiments, endothelial cells were exposed to 10-minute hypoxia (continuous hypoxia) and then exposed to reoxygenation and intermittent hypoxia. In other experiments, the duration of reoxygenation was extended from 2 minutes to 5 minutes. When the donor aorta was exposed to intermittent hypoxia, hypoxia stimulated EDRF(s) release from endothelial cells and the hypoxia-induced EDRF(s) release was augmented by previous hypoxia/reoxygenation. When the donor aorta was exposed to continuous hypoxia, there was no increase of hypoxia-induced EDRF(s) release during hypoxia. But, after the donor aorta was exposed to reoxygenation, hypoxia-induced EDRF(s) release was markedly increased. When the donor aorta was pretreated with nitro-L-arginine $(10^{-5}$ M for 30 minutes), the initial hypoxia-induced EDRF(s) release was almost completely abolished, but the mechanism for EDRF(s) release by the reoxygenation and subsequent hypoxia still remained to be clarified. TEA also blocked incompletely hypoxia-induced and hypoxia/reoxygenation-induced EDRF(s) release. EDRF(s) release by repetitive hypoxia and reoxygenation was completely blocked by the combined treatment with nitro-L-arginine and TEA. Cytochrome P450 blocker, SKF-525A, inhibited the EDRF(s) release reversibly and endothelin antgonists, BQ 123 and BQ 788, had no effect on the release of endothelium-derived vasoactive factors. Superoxide dismutase (SOD) and catalase inhibited the EDRF(s) release from endothelial cells. From these data, it could be concluded that reoxygenation stimulates EDRF(s) release and hypoxia/reoxygenation can release not only NO but also another EDRF from endothelial cells by the production of oxygen free radicals.

• 태양에너지
• /
• 제10권3호
• /
• pp.13-18
• /
• 1990

표면 온도가 균일하지 않은 원통을 균속도 유동장에 가로 놓았을 경우, 표면에서의 열전달 특성은 표면이 등온이거나 일정한 heat flux가 주어졌을 때와는 판이하게 다르다. 본 연구에서는 공기의 균속도 유동장내에서 두가지 경우(step형 및 선형변화)의 비등은 경제조건이 원통면을 따라 원주방향으로 주어졌을 때 표면에서의 열전달 특성을 고찰하였다. Step형 변화는 원통형 태양로의 표면에서 관찰될 수 있다. Solar One(Califomia주의 Barstow시에 있는 태양로)의 경우, 작동유체(물)는 표면을 따라 원주방향과 수직으로 설치된 튜브를 따라 흐르면서 액체상태로부터 고온고압의 증기로 변한다. 이 과정에서 태양로 표면의 receiver panel은 그 위치에 따라, preheater, boiler, 그리고 superheater의 역할을 수행하며 표면의 온도도 균일하지 않은 분포를 나타낸다. 이와 같은 경우 표면의 평균 온도를 가지고 대류에 의한 열 손실을 계산하면 큰 오류를 범할 가능성이 있다.

• 한국식품위생안전성학회지
• /
• 제30권1호
• /
• pp.115-119
• /
• 2015

${\beta}$-cyclodextrin has an ability to protect compounds from oxidative reaction by collecting them within its ring-like structure. So, In harsh condition ($40^{\circ}C$), marker compound, quercetin, was dramatically reduced in Hovenia dulcis fruit extract containing dextrin at 4 and 8 week compared to 0 week, but not that containing ${\beta}$-cyclodextrin. To evaluate the effects of dextrin and ${\beta}$-cyclodextrin on protective effect of H.dulcis fruit extract against alcohol-induced liver damage, The mice were orally injected alcohol, H. dulcis fruit extract/dextrin (HD) and H. dulcis fruit extract/${\beta}$-cyclodextrin (HCD), respectively, for 7 days. The mice orally administrated with alcohol significantly enhanced the serum concentration of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the activity of lactate dehydrogenase (LDH) in serum compared to the control group. HD and HCD significantly decreased the levels of serum ALT and AST and serum LDH activities compared to alcohol group. And also alcohol group significantly increased the level of total cholesterol compared to the control group, but HD and HCD significantly reduced it compared to the alcohol group. However, the levels of TG in blood were not significantly changed in all groups. The activities of alcohol dehydrogenase (ADH) were significantly increased in HD and HCD group although those of aldehyde dehydrogenase showed an increasing tendency. This data suggested that HD and HCD were able to induce alcohol degradation in the liver tissues. All together, the results showed that HCD demonstrated their ability to protect liver from alcohol-induced damage on equal terms with HD.

• Journal of Forest and Environmental Science
• /
• 제25권1호
• /
• pp.1-24
• /
• 2009

Teak (Tectona grandis) is one of the most valuable timber yielding species in the world, with predominant distribution in tropical or sub-tropical countries. However, natural teak available only in few countries like India, Myanmar, Laos People's Democratic Republic and Thailand. Teak grows well in deep, well-drained alluvial soils, fairly moist, warm, tropical climate with pH ranges from 6.5-7.5. Teak is cultivated in many Asian, African and South American countries for timber production. The global teak plantations are estimated to be three million hectare with major share in India (44%) followed by Indonesia (33%). India is considered as richest genetic resources of teak with large areas of natural teak bearing forests (8.9 million ha), plantations (1.5 million ha), clonal seed orchards (1000 ha) and seed production areas (5000 ha). The studies on diversity of teak populations showed that teak is an out crossing species with major portion of diversity present within the populations. The productivity and quality of teak timber varies depending upon the site and environmental conditions. Teak wood is moderately heavy, strong and tough,straight grained, coarse textured and ring porous with specific gravity varies from 0.55 to 0.70. The sapwood is white to pale yellow in colour and clearly demarcated while heartwood is dark brown or dark golden yellow in colour. Teak is one of the most durable timbers in the world, practically, impervious to fungus and white ant attack and resistant to decay. Teak wood is used in ship and boat constructions, furnitures and aesthetic needs. Genetic improvement programmes have been undertaken in countries like Thailand, India, Malaysia and Indonesia. The programme includes provenance identification and testing, plus tree selection and clonal multiplication, establishment of seed orchards and controlled hybridization. Several aspects like phenology, reproductive biology, fruit characteristics, silvicultural practices for cultivation, pest and diseases problems, production of improved planting stock, harvesting and marketing, wood properties and future tree improvement strategy to enhance productivity have been discussed in this paper.

• 대한화학회지
• /
• 제34권1호
• /
• pp.1-9
• /
• 1990

콜레스테릴 펜타노에이트의 결정은 사방정계에 속하며 a = 21.930(3), b = 21.404(3), c = 6.419(5) $\AA$이며 단위세포안에 4개의 분자가 있다. 1.0 $\sigma$ (I)보다 큰 강도를 가진 1,520개의 회절 반점에 대한 최종 R값은 0.086이다. 직접법에 의하여 구조를 풀었으며 C-H 결합길이와 메틸기는 길이를 고정시켜 이상적인 기하학적 구조에 맞춰 cascade diagonal least-squares refinement에 의하여 정밀화하였다. 테트라시클로 고리는 정상적인 구조를 하고 있으나 에스텔과 곁사슬 부분은 열적효과에 의하여 정상적인 길이와 각도의 값에서 변화를 보이고 있으며 에스텔의 끝부분이 굽어져 치켜들고 있다. 분자는 비결합성 van der waals힘에 의하여 서로 쌓여져 있고 가장 짧은 분자간 거리는 3.529 $\AA$이다.

• Bulletin of the Korean Chemical Society
• /
• 제13권4호
• /
• pp.363-367
• /
• 1992

The crystal structure of (1,3,6,9,11,14-hexaazatricycol[12.2.1.$1^{6,9}$]octadecane)copper(Ⅱ) perchlorate, Cu($C_{12}H_{26}N_6$)$(ClO_4)_2$, has been determined by the X-ray diffraction methods. The crystal data are as follows: Mr=516.9, triclinic, ${\alpha}=8.572\;(2)$, b=8.499 (3), c=15.204 (3) ${\AA}$, ${\alpha}=80.42\;(5),\;{\beta}=73.57\;(3),\;{\gamma}=69.82\;(4)^{\circ},\;V=994.2\;{\AA}^3,\;D_C=1.726\;gcm^{-3}$, space group $P{\tilde{1}},\;Z=2,\;{\mu}=21.27\;cm^{-1}&, F(000)=534 and T=297 K. The structure was solved by direct methods and refined by full-matrix least-squares methods to and R value of 0.081 for 1608 observed reflections measured with graphite-mono-chromated Mo Ka radiation on a diffractometer. There are two independent complexes in the unit cell. The two copper ions lie at the special positions (1/2, 0, 0) and (0, 1/2, 1/2)and each complex possesses crystallographic center of symmetry. Each Cu ion is coordinated to four nitrogen donors if the hexaazamacrotricyclic ligand and weakly interacts with two oxygen atoms of the perchlorate ions to form a tetragonally distorted octahedral coordination geometry. The Cu_N (sec), Cu_N(tert) and Cu_O coordination distances are 1.985 (14), 2.055 (14) and 2.757 (13) ${\AA}$ for the complex A and 1.996 (10), 2.040 (11) and 2.660 (13) ${\AA}$ for the complex B, respectively. The macrocycles in the two independent cations assume a similar conformation with the average r.m.s. deviation of 0.073 ${\AA}$. Two 1,3-diazacyclopentane ring moieties of the hexaazamacrotricyclic ligand are placed oppositely and almost perpendicularly to the square coordination plane of the ruffled 14-membered macrocycle. The secondary N atoms are hydrogen-bonded to the perchlorate O atoms with distances of 3.017 (23) and 3.025 (19) ${\AA}$ for the complexes A and B, respectively.

• 대한화학회지
• /
• 제37권3호
• /
• pp.351-354
• /
• 1993

Z-1-에칠-2-니트로-1-부텐일-(4'-메칠)-페닐 슬폰, C$_{13}$H$_{17}$NO$_4$S의 분자량은 283.4으로 a = 12.194(7), b = 7.290(4), c = 16.532(14)${\AA}$, ${\beta}$ = 103.4(2)$^{\circ}$, V = 1429.5 ${\AA}^3$, Z = 4, D$_c$ = 1.32 gcm$^{-3}$, ${\lambda}$(Mo K${\alpha}$) = 0.71069 ${\AA}$, ${\mu}$ = 2.2 cm$^{-1}$, F(000) = 600, T = 298 K으로 단사정계에 계속하여 P2$_1$/c의 공간군을 갖으며 1762rodml I > 1.0${\sigma}$(I)인 회절반점에 대하여 R=0.050이었다. 분자는 메칠벤젠고리에 결합된 S 원자와 NO$_2$기에 결합된 "치환된 부텐골격", C-C(S)=C(NO$_2$)-C으로 이뤄진 cis-형의 분자구조를 갖고 있다. 메칠벤젠고리와 치환된 부텐부분은 거의 평면으로 되어 있으며 그들 자신의 분자평면으로 부터의 각각의 최대편차는 벤젠기의 C(1) 원자의 0.018${\AA}$와 NO$_2$기의 N 원자의 0.045${\AA}$이다. 부텐골격의 평면은 메칠벤젠의 평면과 88.5$^{\circ}$를 또 NO$_2$기와의 평면은 78.6$^{\circ}$를 이루고 있다. 부텐평면으로부터의 NO$_2$기의 회전은 NO$_2$기가 가지고 있는 공명구조의 기여도를 감소하여 SO$_2$기의 O(2) 원자와 NO$_2$기의 O(3) 원자 사이에서 일어나는 반발로 그 거리가 2.8${\AA}$의 예상된 van der vaals 거리보다 긴 2.894 ${\AA}$로 되어 있다.

• 한국광물학회지
• /
• 제30권2호
• /
• pp.45-57
• /
• 2017

$Cd^{2+}$ 이온으로 교환된 제올라이트 Y 단결정은 294 K에서 ${\mid}Na_{75}{\mid}[Si_{117}Al_{75}O_{384}]-FAU$ ($Na_{75}-Y$, Si/Al=1.56)에 0.05 M인 $Cd(NO_3)_2$(pH = 3.65)수용액으로 교환하여 723 K에서 진공 탈수를 통해 준비하였고(crystal 1) 두 번째 결정은 첫 번째 결정과 같이 준비한 뒤 294 K에서 건조된 벤젠을 72시간 동안 노출시켜 준비했다(crystal 2). 이들의 구조는 싱크로트론 X-선을 이용하여 결정학적으로 확인하였고 $F_o$>$4{\sigma}(F_o)$를 사용하여 최종 오차 인자를 각각 $R_1/wR_2=0.040/0.121$ 그리고 0.052/0.168로 정밀화하였다. Crystal $1({\mid}Cd_{36}H_3{\mid}[Si_{117}Al_{75}O_{384}]-FAU)$에서 $Cd^{2+}$이온은 주로 site I과 site IIa에 점유되어 있었고, 이와 더불어 site I', II' 그리고 site IIb에도 $Cd^{2+}$ 이온이 점유되어졌다. Crystal $2({\mid}Cd_{35}(C_6H_6)_{24}H_5{\mid}[Si_{117}Al_{75}O_{384}]-FAU)$에서 $Cd^{2+}$ 이온은 다섯 개의 결정학적 자리에 점유되었다. 24개의 벤젠분자는 supercage 내부에서 두 개의 뚜렷한 자리에서 발견 되었다. 17개의 벤젠분자는 site IIa에 있는 $Cd^{2+}$ 이온과 면상에서 서로 상호작용하였고 supercage 안에서 3회 회전축 상에서 발견되었다. 나머지 7개의 벤젠분자는 12-ring 면상에서 골격(framework)산소들과 함께 약한 다수의 정전기적인 작용과 van der Waals 상호작용으로 안정화되어 있었다.

• Animal Bioscience
• /
• 제35권2호
• /
• pp.260-271
• /
• 2022

Objective: We aimed to investigate the effect of the differing amino acid (AA) release dynamics of two protein sources on the growth performance, nitrogen deposition, plasma biochemical parameters, and muscle synthesis and degradation of piglets when included in their diets at normal and low concentrations. Methods: Forty-eight piglets (Duroc×Landrace×Large White) with initial body weight of 7.45±0.58 kg were assigned to six groups and fed one of 6 diets. The 6 dietary treatments were arranged by 3×2 factorial with 3 protein sources and 2 dietary protein levels. They are NCAS (a normal protein content with casein), NBlend (a normal protein content with blend of casein and corn gluten meal), NCGM (a normal protein content with corn gluten meal), LCAS (a low protein content with casein), LBlend (a low protein content with blend of casein and corn gluten meal), LCGM (a low protein content with corn gluten meal). The release dynamics of AA in these diets were determined by in vitro digestion. The digestibility, utilization and biological value of nitrogen in piglets were determined by micro Kjeldahl method. Plasma insulin was measured by enzyme-linked immunosorbent assay kits. The protein expression of mediators of muscle synthesis and degradation was determined by western blotting. Results: Although the consumption of a low-protein diet supplemented with crystalline AA was associated with greater nitrogen digestion and utilization (p<0.05), the final body weight, growth performance, nitrogen deposition, and phosphorylation of ribosomal protein S6 kinase 1 and eIF4E binding protein 1 in the muscle of pigs in the low-protein diet-fed groups were lower than those of the normal-protein diet-fed groups (p<0.05) because of the absence of non-essential AA. Because of the more balanced release of AA, the casein (CAS) and Blend-fed groups showed superior growth performance, final body weight and nitrogen deposition, and lower expression of muscle ring finger 1 and muscle atrophy F-box than the CGM-fed groups (p<0.05). Conclusion: We conclude that the balanced release of AA from CAS containing diets and mixed diets could reduce muscle degradation, favor nitrogen retention, % intake and improve growth performance in pigs consuming either a normal- or low-protein diet.