• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.53-53
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• 1999

전계방출을 이용한 평판 표시장치는 CRT가 가진 장점을 모두 갖는 동시에 얇고 가벼우며 낮은 전력소모로 완벽한 색을 구현할 수 있는 차세대 표시장치로서 이에 대한 여국가 활발히 이루어지고 있다. 여기에 사용되는 음극물질로서 실리콘이나 몰리 등을 팁모양으로 제작하여 사용해 왔다. 하지만 잔류가스에 의한 역스퍼터링이나 화학적 반응에 의해서 전계방출 성능이 점차 저하되는 등의 해결해야할 많은 문제가 있다. 이러한 문제들을 해결하기 위하여 탄소계 재료로서 다이아몬드, 다이아몬드상 카본 등을 이용하려는 노력이 진행되어 왔다. 이중 유리화 비정형 탄소는 다량의 결함을 가지고 있는 유리질의 고상 탄소 재로로서, 전기전도도가 우수하면서 outgassing이 적고 기계적 강도가 뛰어나며 고온에서도 화학적으로 안정하여 전계방출 소자의 음극재료로서 알맞은 것으로 생각된다. 유리화 비정형 탄소가루를 전기영동법으로 기판에 코팅하여 전계방출 소자를 제작하였다. 전기영동 용액으로 이소프로필알코올에 질산마그네슘과 소량의 증류수, 유리화 비정형 탄소분말을 섞어주었고 기판으로는 몰리(Mo)가 증착된 유리를 사용하였다. 균일한 증착을 위해서 증착후 역전압을 걸어 주는 방법과 증착 후 플라즈마 처리를 하는 등의 여러 가지 방법을 사용했다. 전계방출 전류는 1$\times$10-7Torr이사에서 측정하였다. 1회 제작된 용액으로 반복해서 증착한 횟수에 따라 표면의 거치기, 입자의 분포, 전계방출 측정 결과 등의 차이가 관찰되었다. 발광이미지는 전압에 따라 변화하였고, 균일한 발광을 관찰하기 위해서 오랜 시간동안 aging 과정을 거쳐야 했다. 그리고 구 모양의 양극을 사용해서 위치를 변화시키며 시동 전기장을 관찰하여 위치에 따른 전계방출의 차이를 조사하여 발광의 균일성을 알 수 있었다.on microscopy로 분석하였으며 구조 분석은 X-선 회절분석, X-ray photoelectron spectroscopy 그리고Auger electron spectroscope로 하였다. 증착된 산화바나듐 박막의 전기화학적 특성을 분석하기 위하여 리튬 메탈을 anode로 하고 EC:DMC=1:1, 1M LiPF6 액체 전해질을 사용한 Half-Cell를 구성하여 200회 이상의 정전류 충 방전 시험을 행하였다. Half-Cell test 결과 박막의 결정성과 표면상태에 따라 매우 다른 전지 특성을 나타내었다.도상승율을 갖는 경우가 다른 베이킹 시나리오 모델에 비해 효과적이라 생각되며 초대 필요 공급열량은 200kW 정도로 산출되었다. 실질적인 수치를 얻기 위해 보다 고차원 모델로의 해석이 필요하리라 생각된다. 끝으로 장기적인 관점에서 KSTAR 장치의 베이킹 계획도 살펴본다.습파라미터와 더불어, 본 연구에서 새롭게 제시된 주기분할층의 파라미터들이 모형의 학습성과를 높이기 위해 함께 고려된다. 한편, 이러한 학습과정에서 추가적으로 고려해야 할 파라미터 갯수가 증가함에 따라서, 본 모델의 학습성과가 local minimum에 빠지는 문제점이 발생될 수 있다. 즉, 웨이블릿분석과 인공신경망모형을 모두 전역적으로 최적화시켜야 하는 문제가 발생한다. 본 연구에서는 이 문제를 해결하기 위해서, 최근 local minimum의 가능성을 최소화하여 전역적인 학습성과를 높여 주는 인공지능기법으로서 유전자알고리즘기법을 본 연구이 통합모델에 반영하였다. 이에 대한 실증사례 분석결과는 일일 환율예측문제를 적용하였을 경우, 기존의 방법론보다 더 나운 예측성과를 타나내었다.pective" to workflow architectural discussions. The vocabulary suggested

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.50-50
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• 1999

마이크로 공정을 이용한 초소형 정밀 기계는 공정 기술과 재료 기술의 발전에 의하여 더욱 소형화되고 있으며 특히 기능을 갖는 부분과 이 부분을 제어하는 주변회로의 on-chip화의 요구가 증가되기 시작하였다. 이와 같은 추세에 있어서의 문제점은 초소형 정밀기계 부품 소자의 구동을 위한 에너지원의 개발이다. 즉, 소자의 크기가 작아진 것에 부합되는 초소형의 전지가 필요하게 된 것이다. 따라서 보다 완전한 초소형 정밀 기계 및 마이크로 소자의 구현을 위하여 마이크로 소자와 혼성 (Hybrid) 되어 이용될 수 있는 고성능 및 초소형의 전지의 개발이 필수적이다. 초소형 전지의 구현을 위하여 Li계의 2차 전지를 선택하여 이를 박막화하고 반도체 공정을 도입할 수 있다. 이러한 전지를 박막형 2차 전지 또는 박막형 마이크로 전지(thin film Secondary Battery : TFSB or Thin Film Micro-Battery : TFMB)라 하며 이러한 2차 전지는 일반적인 벌크 전지와 동일하게 cathode/Electolyte/Anode의 구조를 갖는다. 박막의 특성상 전해질은 고상의 물질을 사용하는 것이 벌크형 2차 전지와 다른 점이다. TFSB의 성능은 주로 cathode에 의하여 결정되며 지금까지 많은 cathode 물질에 대한 연구 보고가 발표되고 있다. 반도체 공정을 이용한 TFMB의 제작시 무엇보다 중요한 점은 우수한 고상 전해질 및 anode 물질의 선택에 있다. 최근에 2차 전지를 위한 carbon계 anode를 대체할 수 있는 SnO에 대한 보고가 있는데 이는 한 개의 Sn 원자당 2개 이사의 Li가 반응하여 높은 용량을 갖는 전지의 제작이 가능하기 때문이다. Sno2의 anode는 매우 높은 충전용량을 갖는데 첫 번째 방전시에 Li2O를 생성하여 비가역적 반응을 나타내고 계속되는 충방전 동안 Li-Sn 합금이 생성되어 2차전지의 가역적 반응을 가능하게 한다. SnO2 는 대기중에서 Li 금속보다 안정하기 때문에 전지의 제작 공정 및 사용 면에서 매우 우수한 물질이지만 아직까지 SnO2 구조적 특성과 전지의 충, 방전 특성에 대한 관계의 규명을 위한 정확한 정설은 제시되고 있지 못하다. 본 연구에서는 TFSB anode 물질로써 SnOx박막을 상온에서 여러 전도성 콜렉터 위에 증착하여 그 충, 방전 특성을 보고하였다. 증착된 SnOx박막의 표면은 SEM, AFM으로 분석하였으며 구조의 분석은 XR와 Auger electron spectroscope로 하였다. 충, 방전 특성을 분석하기 위하여 리늄 foil을 대극과 참조 전극으로 하여 EC:DMC=1:1, 1M LiPF6 액체 전해질을 사용한 Half-Cell를 구성하여 100회 이상의 정전류 충, 방전 시험을 행하였다. Half-Cell test 결과 박막의 구조, 콜렉터의 종류 및 Sn/O비에 따라 서로 다른 충, 방전 거동을 나타내었다.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.54-54
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• 1999

다이아몬드 합성시 질소 첨가는 Cn 화합물의 합성가능성을 비롯하여 다이아몬드의 질소 도핑, 성장 속도 및 결정성 변화 등 다양한 관점에서 중요한 의미를 가지고 있다. 본 연구에서는 다이아몬드의 일반적인 합성조건에서 질소를 첨가하여 합성된 막의 형상 및 상 변화에 대해 고찰하였다. 막은 다이아몬드 전처리시킨 Si 기판위에 microwave plasma CVD 장치를 이용하여 합성하였다. 유입되는 혼합가스(CH4+H2+N2)에서 N2 첨가량을 0-95%까지 변화시켰다. 이때 CH4 농도는 5%로 고정하였고, 합성온도는 90$0^{\circ}C$-115$0^{\circ}C$까지 변화시켰다. 이와 같이 합성된 막의 표면조직 및 성장 두께를 측정하기 위해 주사전자현미경을 이용하였다. 상의 분석은 Raman, XRD 및 TEM 분석을 이용하였으며, 조성분석을 위해 XPS 및 AES를 사용하였다. 질소 첨가량에 따라 합성된 막은 첨가하지 않은 경우에 다이아몬드 결정에서 시작하여 질소첨가에 따라 결정면이 깨지는 것으로 나타났다. 그러나 30%, 45%의 경우는 다시 결정면이 나타났다. 다량의 질소가 첨가되었을 때, 다시 결정면을 보이는 다이아몬드가 합성된 것은 매우 흥미로운 결과이다. 한편 질소와 메탄만의 기체하에서는 다시 결정면이 관찰되지 않았다. 이들 상의 구조는 XRD 및 TED 분석을 통해 모두 다이아몬드로 확인되었다. 기체내의 질소의 첨가에 관계없이 고상내에 질소는 확인되지 않았다. 따라서 이방법에 의한 CN 화합물의 합성은 힘든 것으로 보여진다. 이들 실험 결과를 근거로 온도 및 조성에 따른 기체의 열역학적 계산을 통하여 합성거동과의 연관성을 검토하였다. anode는 매우 높은 충전용량을 갖는데 첫 번째 방전시에 Li2O를 생성하여 비가역적 반응을 나타내고 계속되는 충방전 동안 Li-Sn 합금이 생성되어 2차전지의 가역적 반응을 가능하게 한다. SnO2 는 대기중에서 Li 금속보다 안정하기 때문에 전지의 제작 공정 및 사용 면에서 매우 우수한 물질이지만 아직까지 SnO2 구조적 특성과 전지의 충, 방전 특성에 대한 관계의 규명을 위한 정확한 정설은 제시되고 있지 못하다. 본 연구에서는 TFSB anode 물질로써 SnOx박막을 상온에서 여러 전도성 콜렉터 위에 증착하여 그 충, 방전 특성을 보고하였다. 증착된 SnOx박막의 표면은 SEM, AFM으로 분석하였으며 구조의 분석은 XR와 Auger electron spectroscope로 하였다. 충, 방전 특성을 분석하기 위하여 리늄 foil을 대극과 참조 전극으로 하여 EC:DMC=1:1, 1M LiPF6 액체 전해질을 사용한 Half-Cell를 구성하여 100회 이상의 정전류 충, 방전 시험을 행하였다. Half-Cell test 결과 박막의 구조, 콜렉터의 종류 및 Sn/O비에 따라 서로 다른 충, 방전 거동을 나타내었다.다. 거의 없었다. 5mTorr 일 때가 가장 좋았다.수 있음을 알 수 있었다. 그러므로, RNA바이러스의 하나인 BVDV의 viral replicon을 이용하여 다양한 종류의 포유동물 세포에 유전자 발현벡터로써 사용할 수 있음으로 post-genomics시대에 다양한 종류의 단백질 기능연구에 맡은 도움이 되리라 기대한다.다양한 기능을 가진 신소재 제조에 있다. 또한 경제적인 측면에서도 고부가 가치의 제품 개발에 따른 새로운 수요 창출과 수익률 향상, 기존의 기능성 안료를 나노(na

• Korean Journal of Animal Reproduction
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• v.25 no.4
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• pp.371-379
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• 2001

The objective of this study was to establish an effective cryopreservation method of in vitro-produced bovine embryos. For the vitrification, in virtro-produced embryos at 8-cell, morula and blastocyst stages were exposed to freezing solution containing 5.5 M EG (EG 5.5) for 20 sec, loaded on each containers such as EM grid, OPS and Cryo-loop, and then immediately plunged into liquid nitrogen at -196$^{\circ}C$. Thawed embryos were serially diluted in 0.5, 0.25 and 0.125 M sucrose in m-HPBS, each for 1 min, and cultured in CRlaa medium supplemented with 10% FBS. Significant differences in the rates of re-expanded and hatched embryos were not observed among these embryo containers. The total cell number of expanded blastocyst cultured in vitro after vitrification was examined by Hoechst staining. There were no differences between non-vitrified (180.0 $\pm$ 5.4) and vitrified groups (178.0 $\pm$ 7.5). In addition, when the cellular injuries after vitrification were compared by double staining. There were no significant difference in the ratio of live and dead cells between non-vitrified group (176 : 4) and vitrified group (172 : 6). Therefore, these results suggest that bovine embryos can be cryopreserved easily, effectively and successfully by vitrification using various containers, such as EM grid, OPS or Cryo-loop in the presence of EG 5.5 freezing solution.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.6
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• pp.503-516
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• 2020

KCNQ family constitutes slowly-activating potassium channels among voltage-gated potassium channel superfamily. Recent studies suggested that KCNQ4 and 5 channels are abundantly expressed in smooth muscle cells, especially in lower urinary tract including corpus cavernosum and that both channels can exert membrane stabilizing effect in the tissues. In this article, we examined the electrophysiological characteristics of overexpressed KCNQ4, 5 channels in HEK293 cells with recently developed KCNQ-specific agonist. With submicromolar EC₅₀, the drug not only increased the open probability of KCNQ4 channel but also increased slope conductance of the channel. The overall effect of the drug in whole-cell configuration was to increase maximal whole-cell conductance, to prolongate the activation process, and left-shift of the activation curve. The agonistic action of the drug, however, was highly attenuated by the co-expression of one of the β ancillary subunits of KCNQ family, KCNE4. Strong in vitro interactions between KCNQ4, 5 and KCNE4 were found through Foster Resonance Energy Transfer and co-immunoprecipitation. Although the expression levels of both KCNQ4 and KCNE4 are high in mesenteric arterial smooth muscle cells, we found that 1 μM of the agonist was sufficient to almost completely relax phenylephrine-induced contraction of the muscle strip. Significant expression of KCNQ4 and KCNE4 in corpus cavernosum together with high tonic contractility of the tissue grants highly promising relaxational effect of the KCNQ-specific agonist in the tissue.

• The Journal of the Korean Society for Microbiology
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• v.21 no.3
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• pp.311-329
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• 1986

The experimental exposure of animals to sources of ultraviolet radiation (UVR) which emit their energy primarily in the UVB region (280-320nm) is known to result in a number of well-described changes in the recipient's immune competence. Two such changes include a depressed capacity to effectively respond immunologically to transplants of syngeneic UVR tumors and a markedly reduced responsiveness to known inducers of delayedtype (DTH) and contact hypersensitivity (CH) reactions. The results of experiments that were designed to elucidate the mechanisms responsible for UVR-induced immunomodulation have implicated: 1) an altered pattern of lymphocyte recirculation, 2) suppressor T cells(Ts), 3) deviations in systemic antigen presenting cell (APC) potential. 4) changes in the production of interleukin-1-like molecules, and 5) the functional inactivation of epidermal Langerhans cells in this process. The exposure of skin to UVR, therefore, causes a number of both local and systemic alterations to the normal host immune system. In spite of this seeming complexity and diversity of responses, our recent studies have established that each of the UVR-mediated changes is probably of equal importance to creating the UVR-induced immunocompromised state. Normal animals were exposed to low dose UVR radiation on their dorsal surfaces under conditions where a $3.0\;cm^2$ area of skin was physically protected from the light energy. Contact sensitization of these animals with DNFB, to either the irradiated or protected back skin, resulted in markedly reduced CH responses. This was observed in spite of a normal responsiveness following the skin sensitization to ventral surfaces of the UVR-exposed animals. Systemic treatment of the low dose UVR recipients with the drug indomethacin (1-3 micrograms/day) during the UVR exposures resulted in a complete reversal of the depressions observed following DNFB sensitization to "protected" dorsal skin while the altered responsiveness found in the group exposed to the skin reactive chemical through directly UVR-exposed sites was maintained. These studies implicate the importance of EC as effective APC in the skin and also suggest that some of the systemic influences caused by UVR exposure involve the production of prostaglandins. This concept was further supported by finding that indomethacin treatment was also capable of totally reversing the systemic depressions in CH responsiveness caused by high dose UVR exposure (30K joules/$m^2$) of mice. Attempts to analyze the cellular mechanisms responsible established that the spleens of all animals which demonstrated altered CH responses, regardless of whether sensitization was through a normal or an irradiated skin site, contained suppressor cells. Interestingly, we also found normal levels of T effector cells in the peripheral lymph nodes of the UVR-exposed mice that were contact sensitized through normal skin. No effector cells were found when skin sensitization took place through irradiated skin sites. In spite of such an apparent paradox, insight into the probable mechanisms responsible for these observations was provided by establishing that UVR exposure of skin results in a striking and dose-dependent blockade of the efferent lymphatic vessels in all peripheral lymph nodes. Therefore, the afferent phases of immune responses can apparently take place normally in UVR exposed animals when antigen is applied to normal skin. The final effector responses, however, appear to be inhibited in the UVR-exposed animals by an apparent block of effector cell mobility. This contrasts with findings in the normal animals. Following contact sensitization, normal animals were also found to simultaneously contain both antigen specific suppressor T cells and lymph node effector cells. However, these normal animals were fully capable of mobilizing their effector cells into the systemic circulation, thereby allowing a localization of these cells to peripheral sites of antigen challenge. Our results suggest that UVR is probably not a significant inducer of suppressor T-cell activity to topically applied antigens. Rather, UVR exposure appears to modify the normal relationship which exists between effector and regulatory immune responses in vivo. It does so by either causing a direct reduction in the skin's APC function, a situation which results in an absence of effector cell generation to antigens applied to UVR-exposed skin sites, inhibiting the capacity of effector cells to gain access to skin sites of antigen challenge or by sequestering the lymphocytes with effector cell potential into the draining peripheral lymph nodes. Each of these situations result in a similar effect on the UVR-exposed host, that being a reduced capacity to elicit a CH response. We hypothesize that altered DTH responses, altered alloresponses, and altered graft-versus-host responses, all of which have been observed in UVR exposed animals, may result from similar mechanisms.

• Journal of Embryo Transfer
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• v.19 no.1
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• pp.43-51
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• 2004

The present study was conducted to investigate the effects of fusion and/or activation protocol on in vitro development of porcine somatic cell nuclear transfer (SCNT) embryos. Porcine fetal fibroblast cells were transferred into the perivitelline space of enucleated in vitro matured oocytes. Cell fusion and activation were induced simultaneous fusion/activation (SA) or delayed activation (DA) with or without cytochalasin B (CB) treatment with electic pulses in 0.28 M mannitol-based medium. The SCNT embryos were cultured in vitro for 7 days and stained with Hoechst 33342 to determine the number of nuclei. After 7 days culture, cleavage and blastocyst formation rates were 72.4% and 7.6% in SCNT and 76.3% and 20.4% in parthenotes. To examine the effect of electric field strengths on development of SCNT embryos, oocytes were fused two pulses of 110 V/mm, 130 V/mm or 150 V/mm for 30 sec post-injection. The fusion and cleavage rates in 130 V/mm group (70.2% and 72.6%) and 150 V/mm group (72.6% and 70.5%) were higher (P<0.05) than 110 V/mm group (47.1% and 48.6%), respectively. However, the rate of embryos developing to the blastocyst stage (8.1%, 9.7% and 10.7%) were not different among three groups. The cleavage rates and the blastcyst formation rates were not different among three treatment groups (SA group, 71.4% and 9.7%; SA+CB treatment group, 74.7% and 8.0%; DA+CB treatment group, 70.8% and 11.2%, respectively). And, no different in the number of cells in blastocysts was observed among the three groups (22.5$\pm$12.8, 23.3$\pm$11.2 and 21.6$\pm$10.4, respectively). These result suggest that two pulses of 130 V/mm or 150 V/mm for 30 sec with SA treatment or DA treatment are enough for fusion/activation of porcine somatic cell nuclear transfer (SCNT) embryos to develop to the blastocyst stage.

• Journal of Life Science
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• v.20 no.2
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• pp.260-268
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• 2010

The lactate dehydrogenase (EC 1.1.1.27, LDH) isozymes in tissues from Channa argus were purified and characterized by biochemical, immunochemical and kinetic methods. The activity of LDH in skeletal muscle was the highest at 380.4 units and those in heart, eye and brain tissues were 13.4, 3,5 and 5.4 units, respectively. Citrate synthase (EC 4.1.3.7, CS) activity in heart tissue was the highest at 20.7 units. LDH/CS in skeletal muscle, heart, eye and brain tissues were 172.9, 0.6, 0.32 and 0.47. Protein concentration in skeletal muscle tissue was 14.7 mg/g and specific activities of LDH in skeletal muscle, heart, eye and brain tissues were 25.88, 0.79, 0.31 and 1.38 units/mg, respectively. Therefore, skeletal muscle tissue was anaerobic and heart tissue was aerobic. The LDH isozymes in tissues were identified by polyacrylamide gel electrophoresis, immunoprecipitation and Western blot with antiserum against $A_4$, $B_4$, and eye-specific $C_4$. LDH $A_4$, $A_3B$, $A_2B_2$. $AB_3$ and $B_4$ isozymes were detected in every tissue, $C_4$, $AC_3$, $A_2C_2$ and $A_3C$ were detected in eye tissue, and $A_3C$ was found in brain tissue. LDH $A_4$, $A_3B$, $A_2B_2$, $AB_3$, $B_4$, eye-specific $C_4$ isozymes were purified by affinity chromatography and Preparative PAGE Cells. The LDH $A_4$ isozyme was purified in the fraction from elution with $NAD^+$ containing buffer of affinity chromatography. Eye-specific $C_4$ isozyme was eluted right after $A_4$, after which $B_4$ isozyme was eluted with plain buffer. As a result, one part of molecular structures in $A_4$, $B_4$ and eye-specific $C_4$ were similar, but were different from each other in $B_4$ and $C_4$. Therefore the subunit A may be conservative in evolution, and the evolution of subunit B seems to be faster than that of subunit A. The activity of LDH $A_4$, $A_2B_2$, $B_4$, and eye-specific $C_4$ isozymes remained at 39.98, 21.28, 19.67 and 16.87% as a result of the inhibition by 10 mM of pyruvate, so the degree of inhibition was very high. The $Km^{PYR}$ values were 0.17, 0.27 and 0.133 mM in $A_4$, $B_4$ and eye-specific $C_4$ isozymes, respectively. The optimum pH of LDH $A_4$, $B_4$, eye-specific $C_4$, $A_2B_2$, $A_3B$, and $AB_3$ were pH 6.5, pH 8.5, pH 5.5, pH 6.0-6.5, pH 5.0 and pH 7.5. The $A_4$ and heterotetramer isozymes stabilized a broad range of pH. Especially, LDH activities in skeletal muscle tissue were high, resulting in a high degree of muscle activity.LDH metabolism in eye tissue seems to be converted faster from pyruvate to lactate by eye-specific $C_4$ isozyme as eye-specific $C_4$ have the highest affinity for pyruvate, and right after the conversion, oxidation of lactate was induced by $A_4$ isozyme. It was found that expression of Ldh-C, affinity to substrate and reaction time of $C_4$ isozyme were different according to the ecological environmental and feeding capturing patterns.

• Horticultural Science & Technology
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• v.34 no.5
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• pp.736-745
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• 2016

This research was conducted to evaluate the impact of various pre-planting $NH_4{^+}:NO_3{^-}$ ratios on the growth of plug seedlings of 'Bool-am No.3' Chinese cabbage. With fixation of the pre-planting N concentrations to $300mg{\cdot}kg^{-1}$ in a peatmoss+coir dust+perlite (3.5:3.5:3, v/v/v) medium, the $NH_4{^+}:NO_3{^-}$ ratios were varied to 0:100, 27:73, 50:50, 73:27, 100:0. Then, the each of root media containing various ratios of $NH_4{^+}:NO_3{^-}$ as well as equal concentrations of other essential nutrients was packed into 72-cell plug trays. After seeds of 'Bool-am No.3' Chinese cabbage were sown, the seedling growths were measured 2 and 4 weeks after sowing. The weekly analysis of root media and end-crop tissue analysis for mineral nutrients 4 weeks after seed sowing were also conducted. As the seedlings grew up, the pH of the root media increased, however ECs in all treatments of $NH_4{^+}:NO_3{^-}$ ratios decreased. The concentrations of K, Ca and Mg in root media were higher in the treatments of $NH_4{^+}:NO_3{^-}$ (100:0) and $NH_4{^+}:NO_3{^-}$ (73:27) than those of $NH_4{^+}:NO_3{^-}$ (0:100) and $NH_4{^+}:NO_3{^-}$ (27:73) 2 weeks after seed sowing. But the concentrations of K, Ca, Mg and Zn were get lowered in all treatments and the differences among treatments were not significant 4 weeks after sowing. The highest $NH_4{^+}$ and lowest $NO_3{^-}$ concentrations of the root media were observed in the $NH_4{^+}:NO_3{^-}$ (100:0) among all treatments. Contrary to these, the treatment of $NH_4{^+}:NO_3{^-}$ (0:100) had the lowest $NH_4{^+}$ and highest $NO_3{^-}$ concentrations. The seedling growth in terms of fresh and dry weights of aerial part were the highest in the treatment of $NH_4{^+}:NO_3{^-}$ (23:73) at 2 weeks after sowing and those of $NH_4{^+}:NO_3{^-}$ (50:50) at 4 weeks after sowing. The survival rate of seedlings in $NH_4{^+}:NO_3{^-}$ (100:0) treatment were 19% and the growth of aerial part 4 weeks after sowing was the poorest among all treatments tested. The results mentioned above indicate that the pre-planting $NH_4{^+}$ ratio in inert media should not exceed 25% in plug stage 1 through 3 (until 2 true leaf development) and 50% in plug stage 4 (after 2 true leaves to transplant).

• Journal of Chest Surgery
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• v.43 no.4
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• pp.345-355
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• 2010

Background: Extracellular and intracellular pH ($pH_o$ and $pH_i$), which can be changed in various pathological conditions such as hypoxia, affects vascular contractility. To elucidate the mechanism to alter vascular contractility by pH, the effects of pH on reactivity to vasocontracting agents, intracellular $Ca^{2+}$ influx, and $Ca^{2+}$ sensitivity in vascular smooth muscle were examined. Material and Method: Isometric contractions in rat superior mesenteric arteries (SMA) were observed. Intracellular $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) was recorded by microfluorometer using Fura-2/acetoxylmethyl ester in muscle cells. $pH_o$ was increased from 7.4 to 7.8 or decreased to 6.9 or 6.4. $pH_i$ was decreased by applying $NH_4^+$ or propionic acid or modulated by changing $pH_o$ after increasing membrane permeability using $\beta$-escin. Result: Decreases in $pH_o$ from 7.4 to 6.9 or 6.4 shifted concentration-response curve by norepinephrine (NE) or serotonin (SE) to the right and significantly increased half maximal effective concentration (EC50) to NE or SE. Increase in $pH_o$ from 7.4 to 7.8 shifted concentration-response curve by norepinephrine (NE) or serotonin (SE) to the left and significantly reduced EC50 to NE or SE. NE increased $[Ca^{2+}]_i$ in cultured smooth muscle cells from SMA and the increased $[Ca^{2+}]_i$ was reduced by decreases in $pH_o$. NE-induced contraction was inhibited by $NH_4^+$, whereas the resting tension was increased by $NH_4^+$ or propionic acid. When the cell membrane of SMA was permeabilized using ${\beta}$-escin, SMA was contracted by increasing extracellular $Ca^{2+}$ concentration from 0 to $10{\mu}M$ and the magnitude of contraction was decreased by a decrease in $pH_o$ and vice versa. Conclusion: From these results, it can be concluded that a decrease in $pH_o$ might inhibit vascular contraction by reducing the reactivity of vascular smooth muscle to vasoactive agents, $Ca^{2+}$ influx and the sensitivity of vascular smooth muscle to $Ca^{2+}$.