• The Plant Pathology Journal
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• v.21 no.2
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• pp.149-157
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• 2005

A novel rice (Oryza sativa L.) gene, homologous to Arabidopsis pathogenesis-related NDR1 gene, was cloned from cDNA library prepared from 30 min Magnaporthe grisea -treated rice seedling leaves, and named as OsNDR1. OsNDR1 encoded a 220-aminoacid polypeptide and was highly similar to the Arabidopsis AtNDR1 protein. OsNDR1 is a plasma membrane (PM)-localized protein, and presumes through sequence analysis and protein localization experiment. Overexpression of OsNDR1 promotes the expression of PBZ1 that is essential for the activation of defense/stressrelated gene. The OsNDR1 promoter did not respond significantly to treatments with either SA, PBZ, or ETP. Exogenously applied BTH induces the same set of SAR genes as biological induction, providing further evidence for BTH as a signal. Presumably, BTH is bound by a receptor and the binding triggers a signal transduction cascade that has an ultimate effect on transcription factors that regulate SAR gene expression. Thus OsNDR1 may act as a transducer of pathogen signals and/or interact with the pathogen and is indeed another important step in clarifying the component participating in the defense response pathways in rice.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.963-967
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• 2014

Previous studies have suggested anti-tumor effects of asiatic acid in some human cancer cell lines. This agent is reported to increase the levels of $p21^{WAF1/CIP1}$ in human breast cancer cell lines. However, the molecular mechanisms have not been established. Here we report that asiatic acid up-regulates $p21^{WAF1/CIP1}$ protein expression but not the level of $p21^{WAF1/CIP1}$ mRNA in HepG2 human hepatoma cells. Furthermore, we found that the asiatic acid induced increase of $p21^{WAF1/CIP1}$ protein was associated with decreased phosphorylation (ser-146) of $p21^{WAF1/CIP1}$. Knockdown of NDR1/2 kinase, which directly phosphorylates $p21^{WAF1/CIP1}$ protein at ser-146 and enhances its proteasomal degradation, increased the levels of $p21^{WAF1/CIP1}$ protein and eliminated the regulation of $p21^{WAF1/CIP1}$ stability by asiatic acid. At the same time, the expression of NDR1/2 kinase decreased during treatment with asiatic acid in HepG2 cells. Moreover, asiatic acid inhibited the proliferation of HepG2 cells, this being attenuated by knockdown of $p21^{WAF1/CIP1}$. In conclusion, we propose that asiatic acid inhibits the expression NDR1/2 kinase and promotes the stability of $p21^{WAF1/CIP1}$ protein through attenuating NDR1/2 dependent phosphorylation of $p21^{WAF1/CIP1}$ in HepG2 cells.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.366-370
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• 2006

We investigated the negative differential resistance (NDR) property of self-assembled 4,4-di(ethynylphenyl)-2'-nitro-l-(thioacetyl)benzene ('nitro-benzene'), which has been well known as a conducting molecule [1], Self-assembly monolayers (SAMs) were prepared on Au (111), which had been thermally deposited onto pre-treated $(H_2SO_4: H_2O_2=3:1)$ Si, The Au substrate was exposed to a 1mM solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing of the sample, it was exposed to a $0.1{\mu}M$ solution of nitro-benzene in dimethylformamide (DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. Following the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_2Cl_2$, and finally blown dry with $N_2$. Under these conditions, we measured the electrical properties of SAMs using ultra high vacuum scanning tunneling microscopy (UHV-STM) and scanning tunneling spectroscopy (STS) [2]. As a result, we confirmed the properties of NDR in between the positive and negative region.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1568-1570
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• 2003

We have studied the I-V characteristics of polytetrafluoroethylene(PTFE) thin film depending on a variation of thickness. Polymer PTFE buffer layer was made using thermal evaporation technique. The device was made in the structure of ITO/PTFE/Al. We have observed the NDR(negative differential resistance) behavior between 2.5V and 5V. There are some reports on this NDR behavior in the polymer thin film[1]. We have studied the NDR behavior depending on a variation thickness. As the film thickness increased, The NDR behavior decreased and moved in low electrical field, and we have studied the conduction mechanism of PTFE thin film.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.16-19
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• 2006

The characteristic of negative differential resistance(NDR) is decreased current when the applied voltage is increased. The NDR is potentially very useful in molecular electronics device schemes. Here, we investigated the NDR characteristic of self-assembled 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate, which has been well known as a conducting molecule. Self-assembly monolayers(SAMs) were prepared on Au(111), which had been thermally deposited onto $pre-treatment(H_2SO_4:H_2O_2=3:1)$ Si. The Au substrate was exposed to a 1 mM/1 solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing the sample, it was exposed to a 0.1 ${\mu}M/l$ solution of 4.4'-di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene in dimethylformamide(DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. After the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_2Cl_2,$ and finally blown dry with N_2. Under these conditions, we measured electrical properties of self-assembly monolayers(SAMs) using ultra high vacuum scanning tunneling microscopy(UHV-STM). The applied voltages were from -2 V to +2 V with 298 K temperature. The vacuum condition was $6{\time}10^{-8}$ Torr. As a result, we found the NDR voltage of the 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate were $-1.61{\pm}0.26$ V(negative region) and $1.84{\pm}0.33$ V(positive region). respectively.

• The Plant Pathology Journal
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• v.30 no.3
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• pp.254-260
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• 2014

Potato Rpi-blb2 encodes a protein with a coiled-coil-nucleotide binding site and leucine-rich repeat (CC-NBSLRR) motif that recognizes the Phytophthora infestans AVRblb2 effector and triggers hypersensitive cell death (HCD). To better understand the components required for Rpi-blb2-mediated HCD in plants, we used virus-induced gene silencing to repress candidate genes in Rpi-blb2-transgenic Nicotiana benthamiana plants and assayed the plants for AVRblb2 effector. Rpi-blb2 triggers HCD through NbSGT1-mediated pathways, but not NbEDS1- or NbNDR1-mediated pathways. In addition, the role of salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) in Rpi-blb2-mediated HCD were analyzed by monitoring of the responses of NbICS1-, NbCOI1-, or NbEIN2-silenced or Rpi-blb2::NahG-transgenic plants. Rpi-blb2-mediated HCD in response to AVRblb2 was not associated with SA accumulation. Thus, SA affects Rpi-blb2-mediated resistance against P. infestans, but not Rpi-blb2-mediated HCD in response to AVRblb2. Additionally, JA and ET signaling were not required for Rpi-blb2-mediated HCD in N. benthamiana. Taken together, these findings suggest that NbSGT1 is a unique positive regulator of Rpi-blb2-mediated HCD in response to AVRblb2, but EDS1, NDR1, SA, JA, and ET are not required.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.139-141
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• 2005

It is possble to study charge transfer property which is caused by height variation because we can see the organic materials barrier height and STM tip by organic materials energy band gap. Here, we investigated the negative differential resistance(NDR) and charge transfer property of self-assembled 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene, which has been well known as a conducting molecule. Self-assembly monolayers(SAMs) were prepared on Au(111), which had been thermally deposited onto pre-treatment($H_{2}SO_{4}:H_{2}O_{2}$=3:1) Si. The Au substrate was exposed to a 1 mM/l solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing the sample, it was exposed to a $0.1{\mu}M/1$ solution of 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene in dimethylformamide(DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. After the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_{2}Cl_{2}$, and finally blown dry with $N_2$. Under these conditions, we measured electrical properties of self-assembly monolayers(SAMs) using ultra high vacuum scanning tunneling microscopy(UHV-STM). The applied voltages were from -1.50 V to -1.20 V with 298 K temperature. The vacuum condition is $6{\times}10^{-8}$ Torr. As a result, we found that NDR and charge transfer property by a little change of height when the voltage is applied between STM tip and electrode.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1844-1846
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• 2005

The characteristic of negative differential resistance(NDR) is decreased current when the applied voltage is increased. The NDR is potentially very useful in molecular electronics device schemes. Here, we investigated the NDR property of self-assembled 4,4- Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene, which has been well known as a conducting molecule. Self-assembly monolayers(SAMs) were prepared on Au(111), which had been thermally deposited onto pre-treatment$(H_2SO_4:H_2O_2=3:1)$ Si. The Au substrate was exposed to a 1mM/l solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing the sample, it was exposed to a $0.1{\mu}M/l$ solution of 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene in dimethylformamide(DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. After the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_2Cl_2$, and finally blown dry with $N_2$. Under these conditions, we measured electrical properties of self-assembly monolayers(SAMs) using ultra high vacuum scanning tunneling microscopy(UHV-STM). The applied voltages were from -2V to +2V with 299K temperature. The vacuum condition is $6{\times}10^{-8}$ Torr. As a result, we found the NDR voltage of the nitro-benzene is $-1.61{\pm}0.26$ V(negative region) and $1.84{\pm}0.33$ (positive region), respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.622-627
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• 2005

In this study, electrical properties of self-assembled dipyridinium dithioacetate molecule onto the Au(111) substrate is observed using Scanning Tunneling Microscopy(STM) by vortical structure of STM probe. At first, the Au(111) substrate is cleaned by piranha solution$(H_2SO_4:H_2O_2\;=\;3:1)$. Subsequently, 1 mM/ml of dipyridinium dithioacetate molecule is self-assembled onto the Au(111) surface. Using STM, the images of dipyridinium dithioacetate molecule which is self-assembled onto the Au(111) substrate, can be observed. In addition, the electrical properties(I-V) of dipyridinium dithioacetate can also be examined by using Scanning Tunneling Spectroscopy(STS). From the results of the measurement of the current-voltage(I-V), the property of Negative Differential Resistance(NDR) that shows the decreases of current according to the increases of voltage is observed. We found the NDR voltage of the dipyridinium dithioacetate is -1.42 V(negative region) and 1.30 V(positive region), respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.485-488
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• 2004

본 연구에서는 dipyridinium dithioacetate 분자를 Au(111) 표면에 자기조립하여 STM 탐침-유기 단분자막-Au(111)기판의 수직구조로 STM 측정시스템을 이용하여, 전기적 특성을 관찰하였다. 먼저 Au(111)기판을 Piranha용액$(H_2SO_4:H_2O_2=3:1)$으로 Au 표면을 전처리 하였다. 전처리한 Au(111) 기판을 dipyridinium dithioacetate 1mol/ml 농도로 자기조립 하였으며, 자기조립막의 표면 구조를 STM으로 관찰하였다. dipyridinium dithioacetate의 전기적 특성은 STM 탐침-유기단분자막-Au(111) 기판의 수직구조로 STS를 이용하여 조사하였다. 전압과 전류 측정에서 전압이 증가함에 따라 전류가 감소하는 부성 미분저항(NDR)의 특성이 관찰 되었다. NDR 수치가 $-545\;[m\Omega/cm^2]$였고, PVCR은 1.64:1 이었다.