We report on the efficient detection of NO gas by an all-oxide semiconductor p-n heterojunction diode structure comprised of n-type zinc oxide (ZnO) nanorods embedded in p-type copper oxide (CuO) thin film. The CuO thin film/ZnO nanorod heterostructure was fabricated by directly sputtering CuO thin film onto a vertically aligned ZnO nanorod array synthesized via a hydrothemal method. The transport behavior and NO gas sensing properties of the fabricated CuO thin film/ ZnO nanorod heterostructure were charcterized and revealed that the oxide semiconductor heterojunction exhibited a definite rectifying diode-like behavior at various temperatures ranging from room temperature to 250 oC. The NO gas sensing experiment indicated that the CuO thin film/ZnO nanorod heterostructure had a good sensing performance for the efficient detection of NO gas in the range of 2-14 ppm under the conditions of an applied bias of 2 V and a comparatively low operating temperature of 150 oC. The NO gas sensing process in the CuO/ZnO p-n heterostructure is discussed in terms of the electronic band structure.

We present the rectifying and nitrogen monoxide (NO) gas sensing properties of an oxide semiconductor heterostructure composed of n-type zinc oxide (ZnO) and p-type copper oxide thin layers. A CuO thin layer was first formed on an indium-tin-oxide-coated glass substrate by sol-gel spin coating method using copper acetate monohydrate and diethanolamine as precursors; then, to form a p-n oxide heterostructure, a ZnO thin layer was spin-coated on the CuO layer using copper zinc dihydrate and diethanolamine. The crystalline structures and microstructures of the heterojunction materials were examined using X-ray diffraction and scanning electron microscopy. The observed current-voltage characteristics of the p-n oxide heterostructure showed a non-linear diode-like rectifying behavior at various temperatures ranging from room temperature to 200 oC. When the spin-coated ZnO/CuO heterojunction was exposed to the acceptor gas NO in dry air, a significant increase in the forward diode current of the p-n junction was observed. It was found that the NO gas response of the ZnO/CuO heterostructure exhibited a maximum value at an operating temperature as low as 100 oC and increased gradually with increasing of the NO gas concentration up to 30 ppm. The experimental results indicate that the spin-coated ZnO/CuO heterojunction structure has significant potential applications for gas sensors and other oxide electronics.

We present the detection characteristics of nitrogen monoxide(NO) gas using p-type copper oxide(CuO) thin film gas sensors. The CuO thin films were fabricated on glass substrates by a sol-gel spin coating method using copper acetate hydrate and diethanolamine as precursors. Structural characterizations revealed that we prepared the pure CuO thin films having a monoclinic crystalline structure without any obvious formation of secondary phase. It was found from the NO gas sensin measurements that the p-type CuO thin film gas sensors exhibited a maximum sensitivity to NO gas in dry air at an operating temperature as low as 100 oC. Additionally, these CuO thin film gas sensors were found to show reversible and reliable electrical response to NO gas in a range of operating temperatures from 60 oC to 200 oC. It is supposed from these results that the ptype oxide semiconductor CuO thin film could have significant potential for use in future gas sensors and other oxide electronics applications using oxide p-n heterojunction structures.

저온은 식물 생장을 저해하는 주된 요인이며 병원균에 대한 감수성을 증가시킨다. 그러므로 식물체에서 스트레스 내성을 증대시키는 것은 불리한 환경 조건에서 살아 남기 위한 중요한 전략이다. 본 실험의 목적은 고추 묘에서 저온 내성과 식물병 발생에 대한 외생 살리실산(SA)과 일산화질소(NO) 처리의 효과를 밝히는 것이다. 정식 후 23일 동안 고추 묘(Capsicum annuum L. ‘기대만발’)는 온도 20/25oC(낮/밤), 광주기 15시간, 광도 145±5μmol·m−2·s−1 의 정상적인 생육환경에서 자랐다. 1주일에 2번 계면활성 제 0.1%를 포함한 SA와 NO 3mL을 고추 묘에 각각 분사 해주었다. 처리 후 고추 묘는 암 상태에서 6시간 동안 4oC 저온에 노출시킨 후 정상적인 생육환경에서 2일 동안 회복시켜주었다. 저온 스트레스에 대한 식물 내성을 평가 하기 위해 저온 처리 후 생육특성, 엽록소 형광 값, 세포 막 투과성을 측정하였다. 총 페놀릭 농도와 항산화도는 실험하는 동안 측정하였다. 또한, 고추의 점무늬병과 풋마름 병 발생 정도도 조사하였다. 저온 처리 전·후를 비교하여 대조구 고추묘에서는 저온에 의해 상대적으로 많은 수분을 손실하여 건물율이 높지만 SA와 NO 처리 된 고추 묘는 비슷한 건물율을 유지하였다. 저온 처리 후 대조구에 비해 SA와 NO 처리구의 전해질 유출 값은 더 낮았다. 저온 처리 동안 SA와 NO 처리구의 엽록소 형광값은 약 0.8 수준으로 유지하였지만 대조구는 빠르게 감소하였다. 화학적 처리 동안 SA 처리구의 총 페놀릭 농도와 항산화도는 NO 처리구보다 높았다. 또한 저온 처리 후 대조구와 NO 처리구의 총 페놀릭 농도는 증가하였다. 고추에서 풋마름병에 대한 저항성은 SA가 보다 효과적이었다. 본 실험의 결과는 SA와 NO의 외생처리는 고추 묘의 저온 내성을 증대시켰고 병 발생 정도를 감소시키는 데 효과적이었음을 보여준다.

We report the nitrogen monoxide (NO) gas sensing properties of p-type CuO-nanorod-based gas sensors. We synthesized the p-type CuO nanorods with breadth of about 30 nm and length of about 330 nm by a hydrothermal method using an as-deposited CuO seed layer prepared on a Si/SiO2 substrate by the sputtering method. We fabricated polycrystalline CuO nanorod arrays at 80˚C under the hydrothermal condition of 1:1 morality ratio between copper nitrate trihydrate [Cu(NO2)2·3H2O] and hexamethylenetetramine (C6H12N4). Structural characterizations revealed that we prepared the pure CuO nanorod array of a monoclinic crystalline structure without any obvious formation of secondary phase. It was found from the gas sensing measurements that the p-type CuO nanorod gas sensors exhibited a maximum sensitivity to NO gas in dry air at an operating temperature as low as 200˚C. We also found that these CuO nanorod gas sensors showed reversible and reliable electrical response to NO gas at a range of operating temperatures. These results would indicate some potential applications of the p-type semiconductor CuO nanorods as promising sensing materials for gas sensors, including various types of p-n junction gas sensors.

We investigated the detection properties of nitrogen monoxide (NO) gas using transparent p-type CuAlO2 thin film gas sensors. The CuAlO2 film was fabricated on an indium tin oxide (ITO)/glass substrate by pulsed laser deposition (PLD), and then the transparent p-type CuAlO2 active layer was formed by annealing. Structural and optical characterizations revealed that the transparent p-type CuAlO2 layer with a thickness of around 200 nm had a non-crystalline structure, showing a quite flat surface and a high transparency above 65 % in the range of visible light. From the NO gas sensing measurements, it was found that the transparent p-type CuAlO2 thin film gas sensors exhibited the maximum sensitivity to NO gas in dry air at an operating temperature of 180˚C. We also found that these CuAlO2 thin film gas sensors showed reversible and reliable electrical resistance-response to NO gas in the operating temperature range. These results indicate that the transparent p-type semiconductor CuAlO2 thin films are very promising for application as sensing materials for gas sensors, in particular, various types of transparent p-n junction gas sensors. Also, these transparent p-type semiconductor CuAlO2 thin films could be combined with an n-type oxide semiconductor to fabricate p-n heterojunction oxide semiconductor gas sensors.

We report on the NO gas sensing properties of non-directional ZnO nanofibers synthesized using a typical electrospinning technique. These non-directional ZnO nanofibers were electrospun on an SiO2/Si substrate from a solution containing poly vinyl alcohol (PVA) and zinc nitrate hexahydrate dissolved in distilled water. Calcination processing of the ZnO/PVA composite nanofibers resulted in a random network of polycrystalline ZnO nanofibers of 50 nm to 100 nm in diameter. The diameter of the nanofibers was found to depend primarily on the solution viscosity; a proper viscosity was maintained by adding PVA to fabricate uniform ZnO nanofibers. Microstructural measurements using scanning electron microscopy revealed that our synthesized ZnO nanofibers after calcination had coarser surface morphology than those before calcination, indicating that the calcination processing was sufficient to remove organic contents. From the gas sensing response measurements for various NO gas concentrations in dry air at several working temperatures, it was found that gas sensors based on electrospun ZnO nanofibers showed quite good responses, exhibiting a maximum sensitivity to NO gas in dry air at an operating temperature of 200˚C. In particular, the non-directional electrospun ZnO nanofiber gas sensors were found to have a good NO gas detection limit of sub-ppm levels in dry air. These results illustrate that non-directional electrospun ZnO nanofibers are promising for use in low-cost, high-performance practical NO gas sensors.

We report on the NO gas sensing properties of Al-doped zinc oxide-carbon nanotube (ZnO-CNT) wire-like layered composites fabricated by coaxially coating Al-doped ZnO thin films on randomly oriented single-walled carbon nanotubes. We were able to wrap thin ZnO layers around the CNTs using the pulsed laser deposition method, forming wire-like nanostructures of ZnO-CNT. Microstructural observations revealed an ultrathin wire-like structure with a diameter of several tens of nm. Gas sensors based on ZnO-CNT wire-like layered composites were found to exhibit a novel sensing capability that originated from the genuine characteristics of the composites. Specifically, it was observed by measured gas sensing characteristics that the gas sensors based on ZnO-CNT layered composites showed a very high sensitivity of above 1,500% for NO gas in dry air at an optimal operating temperature of 200˚C; the sensors also showed a low NO gas detection limit at a sub-ppm level in dry air. The enhanced gas sensing properties of the ZnO-CNT wire-like layered composites are ascribed to a catalytic effect of Al elements on the surface reaction and an increase in the effective surface reaction area of the active ZnO layer due to the coating of CNT templates with a higher surface-to-volume ratio structure. These results suggest that ZnO-CNT composites made of ultrathin Al-doped ZnO layers uniformly coated around carbon nanotubes can be promising materials for use in practical high-performance NO gas sensors.

Semiconducting metal oxides have been frequently used as gas sensing materials. While zinc oxide is a popular material for such applications, structures such as nanowires, nanorods and nanotubes, due to their large surface area, are natural candidates for use as gas sensors of higher sensitivity. The compound ZnO has been studied, due to its chemical and thermal stability, for use as an n-type semiconducting gas sensor. ZnO has a large exciton binding energy and a large bandgap energy at room temperature. Also, ZnO is sensitive to toxic and combustible gases. The NO gas properties of zinc oxide-single wall carbon nanotube (ZnO-SWCNT) composites were investigated. Fabrication includes the deposition of porous SWCNTs on thermally oxidized SiO2 substrates followed by sputter deposition of Zn and thermal oxidation at 400˚C in oxygen. The Zn films were controlled to 50 nm thicknesses. The effects of microstructure and gas sensing properties were studied for process optimization through comparison of ZnO-SWCNT composites with ZnO film. The basic sensor response behavior to 10 ppm NO gas were checked at different operation temperatures in the range of 150-300˚C. The highest sensor responses were observed at 300˚C in ZnO film and 250˚C in ZnO-SWCNT composites. The ZnO-SWCNT composite sensor showed a sensor response (~1300%) five times higher than that of pure ZnO thin film sensors at an operation temperature of 250˚C.

We investigated the NO gas sensing characteristics of ZnO-carbon nanotube (ZnO-CNT) layered composites fabricated by coaxial coating of single-walled CNTs with a thin layer of 1 wt% Al-doped ZnO using rf magnetron sputtering deposition. Morphological studies clearly revealed that the ZnO appeared to form beadshaped crystalline nanoparticles with an average diameter as small as 30 nm, attaching to the surface of the nanotubes. It was found that the NO gas sensing properties of the ZnO-CNT layered composites were dramatically improved over Al-doped ZnO thin films. It is reasoned from these observations that an increase in the surface-to-volume ratio associated with the numerous ZnO “nanobeads” on the surface of the CNTs results in the enhancement of the NO gas sensing properties. The ZnO-CNT layered composite sensors exhibited a maximum sensitivity of 13.7 to 2 ppm NO gas at a temperature of 200˚C and a low NO gas detection limit of 0.2 ppm in dry air.

We investigated the effects of Co doping on the NO gas sensing characteristics of ZnO-carbon nanotube (ZnO-CNT) layered composites fabricated by coaxial coating of single-walled CNTs with ZnO using pulsed laser deposition. Structural examinations clearly confirmed a distinct nanostructure of the CNTs coated with ZnO nanoparticles of an average diameter as small as 10 nm and showed little influence of doping 1 at.% Co into ZnO on the morphology of the ZnO-CNT composites. It was found from the gas sensing measurements that 1 at.% Co doping into ZnO gave rise to a significant improvement in the response of the ZnO-CNT composite sensor to NO gas exposure. In particular, the Co-doped ZnO-CNT composite sensor shows a highly sensitive and fast response to NO gas at relatively low temperatures and even at low NO concentrations. The observed significant improvement of the NO gas sensing properties is attributed to an increase in the specific surface area and the role as a catalyst of the doped Co elements. These results suggest that Co-doped ZnOCNT composites are suitable for use as practical high-performance NO gas sensors.

The NO gas sensing properties of ZnO-carbon nanotube (ZnO-CNT) composites fabricated by the coaxial coating of single-walled CNTs with ZnO were investigated using pulsed laser deposition. Upon examination, the morphology and crystallinity of the ZnO-CNT composites showed that CNTs were uniformly coated with polycrystalline ZnO with a grain size as small as 5-10 nm. Gas sensing measurements clearly indicated a remarkable enhancement of the sensitivity of ZnO-CNT composites for NO gas compared to that of ZnO films while maintaining the strong sensing stability of the composites, properties that CNT-based sensing materials do not have. The enhanced gas sensing properties of the ZnO-CNT composites are attributed to an increase in the surface adsorption area of the ZnO layer via the coating by CNTs of a high surface-to-volume ratio structure. These results suggest that the ZnO-CNT composite is a promising template for novel solid-state semiconducting gas sensors.

ZnO nanorod gas sensors were prepared by an ultrasound radiation method and their gas sensing properties were investigated for NO gas. For this procedure, 0.01, 0.005 and 0.001M of zinc nitrate hydrate [Zn(NO3)2 · 6H2O] and hexamethyleneteramine [C6H12N4] aqueous solutions were prepared and then the solution was irradiated with high intensity ultrasound for 1 h. The lengths of ZnO nanorods ranged from 200 nm to 500 nm with diameters ranging from 40 nm to 80 nm. The size of the ZnO nanorods could be controlled by the concentration of solution. The sensing characteristics of these nanostructures were investigated for three kinds of sensor. The properties of the sensors were influenced by the morphology of the nanorods.

In the present study, we have demonstrated that a novel synthetic chemical JSH-21 of N¹-Benzyl-4-methylbenzene-1,2-diamine could inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-activated macrophages RAW 264.7. The JSH-21 showed an IC50 value of 9.2 uM on the LPS-induced NO production. Furthermore, JSH-21 attenuated LPS-induced mRNA and protein levels of inducible NO synthase (iNOS) in the cells, as well as inhibited LPS-induced iNOS promoter activity. These results indicates hat the compound could down-regulate iNOS expression at the transcription level. Since NF-kB activation is a key mechanism in the expression of LPS-inducible iNOS gene, we further examined whether JSH-21 could affect LPS-induced NF-kB activation. JSH-21 inhibited LPS-induced nuclear import of NF-kB p65 in macrophages RAW 264.7 and sequentially prevented NF-kB transcriptional activity. However, JSH-21 was not effective in a LPS-induced degradation of cytoplasmic IkB-alpha in the cells. These results suggest that JSH-21 could inhibit LPS-induced NF-kB activation targeting nuclear import of NF-kB, an event downstream IkB degradation. Taken together, this study may provide a pharmacological potential of JSH-21 in the NO- or NF-kB-associated inflammatory disorders.

We have examined the effect of NO donor, S-nitl‘ oso-N-acetyl-DL-penicillamine(SNAP) on heme oxygenase-1 (HQ-l) ex pression in human oral immortalized & malignant keratinocytes, and investigated in the control of keratinocyte proliferation evidence tha t HO-1 cou ld be involved in a low dose of NO, NO inhibitor, HOinducer, and HO inhibitor medi ated cytoprotect ion against cytotoxi city induced by a high dose of NO Oral keratinocyte growth inhibitory or anti-proliferative effects were exerted by with SNAP and hemin in a dose- and cul tivation time dependent manner The level of HQ-1 protein was increased in all cell types after exposure hernin dose, and the hemin induced HQ-1 protein achieved at higher maximum level by 12 hrs in all kind of cells , The pretreatment of cells with 0, 2 μ M SNAP reduced 1 mM SNAP-induced death in IHOK and HN4 cells , These cytoprotective effects on high dose of NO induced HQ-1 expresion and cell ular toxicity were blocked by low dose of SNAP, HCB, and ZnPP IX supporting the involvement of HQ-1 in high dose NO induced growth arrest or cell death, But these cytoprotection pattern is different from immortalized and malignant keratinocytes , These results indirectly demonstrate that HQ-1 could be involved in cytoprotection by NO priming against high dose NO induced cytotoxicity in immortalized and maigla nt oral keratinocytes, Thus, HQ-1 might be an important cellular target of NO donor, with clinical implications for the pre vention of inJlammatory di seases and anti-tumor immunity

Nitric oxide (NO) has been known to inf1uence cell fate through apoptotic or necrotic cell death. Here, we investigated the role of nitric oxide on the growth and viability of immortalized human salivary gland (HSG) cells 띠 vitro. Treatrnent of HSG with a NO donor, S-nitroso-N-acetyl-DL-penκi1lamine (SNAP), significantly diminished the growth rate of HSG in a concentration dependent manner. However, this retardation of cell비ar growth rate was not corresponded to the apoptotic cell death of HSG cells, because there were no characteristic apopto디c features such as condensation of nuclear chromatin, nuclear fragmentation, and the apoptotic peak of propidium iodide (PI)-stained nuclei by flow cytome띠. 까ùs implies that HSG cells are resistant to NO-mediated 다π。to:잉city. 1n SNAP treated HSG cells, cell cycle analysis revealed that the number of G2/M phase increased markedly, according to while the percentage of cells in GO/Gl and S phases was not significantly affected. Otherwise, high concentrations of SNAP increased both P1 and annexin V positive cells. 1nterestingly, preincubation of HSG cells with iron chelator, deferoxamine (DFO), significantly diminished NO cytotoxicity more than when HSG cells are only incubated with SNAP which su잃.ests the role of iron homeostasis in NO-mediated cell death of HSG cells. 1n addi디。n ， treatrnent of HSG cells with SNAP specifically cleaved iron regulatory protein-2 (IRP2) while not affecting 1RP1. Collectively, the mπent results s멍gest that NO has a potential to control HSG cell growth through cell cycle arresting at G2/M phase. 1n addi디on ， intracellular iron homeostasis nùght play an important role in regulating cell survival of HSG cells

태국산과 베트남산의 용안육 원료 및 그 발효물의 전자공여능, 일산화질소(NO) 생성효과, 인체암 세포주인 자궁경부암세포(HeLa) 및 간암세포(HepG2)의 항암활성 효과를 조사하였다. 원료 용안육의 총 유기산은 태국산 용안육(473.49 mg/g)이 베트남산(148.48 mg/g) 용안육에 비하여 3.2배 높은 함량을 나타내었고, 전체 유기산의 각각 89.2%와 86.8%를 나타내었으며, 주요 유기산은 formic acid와 malic acid