• Title, Summary, Keyword: NR

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Nanodiamond/gold nanorod nanocomposites with tunable light-absorptive and local plasmonic properties

  • Lee, Dukhee;Jeong, Seong Hoon;Kang, Eunah
    • Journal of Industrial and Engineering Chemistry
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    • v.65
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    • pp.205-212
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    • 2018
  • Nanodiamonds (NDs) have potential as platform materials for biological and biomedical applications depending on the combinatorial complex designs. Bimetallic nanocomposites with ND and gold nanorods (AuNRs) were synthesized and obtained at tunable UV absorption wavelengths by controlling the aspect ratio of AuNR. The nanodiamond/AuNR nanocomposites (NDAuNR) with fine tuning ultraviolet/visible/near-infrared (UV-vis-NIR) extinction were prepared using a cetyltrimethylammonium bromide (CTAB)-surfactant-based seedless growth method. NDAuNRs varied with UV absorption wavelengths and aspect ratios, providing the surface-enhanced Raman scattering (SERS) effect. Compared to AuNR/800 nm with the same UV absorption wavelength, NDAuNR/800 nm showed 12.1% and 9.8% higher SERS intensity ratios of $I_{1620}/I_{520}$ and $I_{420}/I_{520}$, respectively, for methylene blue of concentration $10^{-5}M$. The enhanced SERS intensity of NDAuNR/800 nm indicates that electron mobility was facilitated at the interface between ND and AuNRs, and a larger contact area owing to a larger aspect ratio resulted in a higher SERS effect. The study demonstrated that NDAuNR nanocomposites enhanced the photo-responsive reactivity in SERS, resulting in potentially promising biomedical applications in sensor, imaging, and photothermal therapy. NDs provide platform substances to magnify gold resonance.

Natural Rubber Economics between China and Southeast Asia: The Impact of China's Economic Slowdown

  • OKTORA, Siskarossa Ika;FIRDANI, Alfada Maghfiri
    • The Journal of Asian Finance, Economics and Business
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    • v.6 no.2
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    • pp.55-62
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    • 2019
  • China has become the second largest economy since 2010. China's economy is supported by the rapid growth of its automobile industry. The rapid growth of the automobile and tire industry will increase the natural rubber (NR) demand as its primary raw materials. Although as a significant producer, China cannot fulfill the consumption by its domestic production. Thus China relies heavily on import from Southeast Asia countries as the primary producers of natural rubber in the world. China and Southeast Asia are dependent on their economy in terms of the availability of natural rubber as raw materials. But the economic slowdown in China since 2008 is expected to affect the international trading between China and Southeast Asia countries. This research aims to analyze the determinants of NR export from Southeast Asia to China using panel data analysis. The results show NR price, exchange rate, and China's economic slowdown significantly affect NR export to China, while Southeast Asian NR production has no significant effect. China as the main importer of NR from Southeast Asia has a big role in growing NR export in Southeast Asia. If China's economy doesn't improve soon, it will affect the economy in Southeast Asia.

Mechanical Properties of Natural Rubber/Acrylonitrile-Butadiene Rubber Blends and Their Adhesion Behavior with Steel Cords (Natural Rubber/Acrylonitrile-Butadiene Rubber 블렌드의 기계적 물성과 강선과의 접착거동)

  • Sohn, Bong-Young;Nah, Chong-Woon
    • Elastomers and Composites
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    • v.36 no.2
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    • pp.111-120
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    • 2001
  • Mechanical properties and their adhesion behavior with zinc- and brass-plated steel cords of natural rubber/acrylonitrile-butadiene blend compounds were investigated as a function of blend ratio. The Mooney viscosity and stress relaxation time were found to be lowered with increasing NBR content. Tensile modulus generally increased with increasing NBR content. Tensile stress at break stayed constant up to about 40 phr and showed minimum at $50{\sim}60 phr$, and thereafter increased with increasing NBR content. Strain at break decreased linearly below 50 phr, and above the level it showed nearly constant value. Based on the abrupt drops in elastic modulus and tan ${\delta}$ peak, the glass transition temperature of NR and NBR were found to be -55 and $-10^{\circ}C$, respectively. In the case of NR/NBR blend compounds, two distinct transition points were observed and each transition position was not affected by NBR level indicating an incompatible nature of NR/NBR blend system. The pullout force and rubber coverage decreased to the level of about 40% to that of pure m compound, when the 50 phr of NR was replaced by NBR. However, the pure NBR compound showed the comparable adhesion performance with NR(${\sim}90%$). The sulfur concentration was found to become lower with the increased NBR content at the adhesion interface based on the Auger spectrometer results, representing a lack of adhesion layer formation, and this was explained for a possible cause of low adhesion performance with adding NBR.

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Natural Rubber-Clay Nanocomposites by Latex Method : Morphology and Mechanical Properties (라텍스법에 의한 천연고무-클레이 나노 복합재료: 모폴로지와 기계적 물성)

  • Kim, W.H.;Kang, J.H.;Kang, B.S.;Cho, U.R.
    • Elastomers and Composites
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    • v.41 no.1
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    • pp.27-39
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    • 2006
  • In this study, modified DA-MMT filled NR/DA-MMT nanocomposites were manufactured by a latex method and a compounding method. Cure characteristics and mechanical properties of the Cloisite 15A, carbon black, Na-MMT filled NR compounds and the DA-MMT filled NR compound by a latex method were also evaluated. The filler content of all compounds was 10phr except the carbon black filled compound. Degree of intercalation and dispersion was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). According to the XRD diffraction pattern and TEM analysis, extensive intercalation and homogeneous dispersion of the clay were obtained after the two-roll milling. Although the layer distance was increased, some parts of DA-MMT showed the layer distance of Na-MMT after vulcanization. DA-MMT filled NR compounds showed the highest ODR torques, tensile strength, modulus, and tear energy. The NR/DA-MMT nanocomposite (by a latex method) compared with a NR/DA-MMT nanocomposite (by a compounding method) was found that the improvement of the mechanical properties was mainly due to the degree of dispersion of the clay.

Studios on the Parasites of the Rice Planthoppers I. Egg Parasitism Anagrus nr. flaveolus WATERHOUSB (Hymenoptera : Mymmaridae) on the Rice Planthoppers (멸구 매미충의 기생성 천적에 관한 연구 I. Anagrus nr. flaveolus의 멸구류 난기생에 관하여)

  • Kim J.P.;Yoo C.Y.;Kim C.H.
    • Korean journal of applied entomology
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    • v.21 no.2
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    • pp.87-94
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    • 1982
  • The mymarids egg parasite of rice planthopper, Anagrus nr. flaveolus, were investigated to know their parasitic activities after overwitering in the paddy banks and barley fields, their host preferences and seasonal variations in the pesticide sprayed and unsprayed paddy fields of Gyeongnam province O.R.D. at Jinju from 1977 to 1979. The parasitic activities of Anagrus nr. flaveolus after overwintering in the paddy banks were high early in April and tended to decrease remarkably since mid-April by moving to the barley fields. The parasitic rate of Anagrus nr. flavelous was $47.2\~88\%$ between middle and late in April, the peak of egg deposition period. Anagrus nr. flaveolus parasitized Laodelphax striatellus, Nilaparvata lugens, and Sogatella furcifera, but didn't attack the eggs of Nephotettix cincticeps in the paddy fields. High preference was observed with Laodelphax steriatellus. The parasitic activities of Anagrus nr. flaveolus in the pesticide sprayed paddy fields were high in early July and from late August to early September. The parasitic rate in the pesticide unsprayed fields were higher than those of sprayed fields during the pesticide spraying period, from July to August and parasitic activities were active from October to before coming winter.

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Modulation in NMDA and $GABA_A$ Receptor Expression after Cerebroventricular Infusion of Ginsenosides

  • Oh Seikwan;Kim Hack-Seang
    • Proceedings of the Ginseng society Conference
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    • pp.96-112
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    • 2002
  • In the present study, we have investigated the effects of centrally administered ginsenoside Rc or Rgl on the modulation of NMDA receptor and $GABA_A$ receptor binding in rat brain. The NMDA receptor binding was analyzed by quantitative autoradiography using $[^3H]MK-801$ binding, and $GABA_A$ receptor bindings were analyzed by using $[^3H]muscimol\;and\;[^3H]flunitrazepam$ in rat brain slices. Rats were infused with ginsenoside Rc or Rg1 ($10\;{\mu}g/10{\mu}l/hr$, i.c.v.) for 7 days, through pre-implanted cannula by osmotic minipumps (Alzet, model 2ML), The levels of $[^3H]MK-801$ binding were highly decreased in part of cortex and cingulated by ginsenoside Rc and Rgl. The levels of $[^3H]muscimol$ binding were strongly elevated in almost all regions of frontal cortex by the treatment of ginseoside Rc but decreased by ginsenoside Rg 1. However, the $[^3H]flunitrazepam$ binding was not modulated by ginsenoside Rc or ginsenoside Rgl infusion. These results suggest that prolonged infusion of ginsenoside could differentially modulate $[^3H]MK-801\;and\;[^3H]muscimol$ binding in a region-specific manner. Also, we investigated the influence of centrally administered ginsenoside on the regulation of mRNA levels of the family of NMDA receptor subtypes (NR1, NR2A, NR2B, NR2C) by in situ hybridization histochemistry in the rat brain. The level of NR1 mRNA is significantly increased in temporal cortex, caudate putamen, hippocampus, and granule layer of cerebellum in Rgl-infused rats as compared to control group. The level of NR2A mRNA is elevated in the frontal cortex. In contrast, it was decreased in CAI area of hippocampus in Rgl-infused rats. However, there was no significant change of NR1 and NR2A mRNA levels in Rc-infused rats. The level of NR2B mRNA is elevated in cortex, caudate putamen, and thalamus in both Rc- and Rg-infused rats. In contrast, NR2B level is decreased in CA3 in Rgl-infused rats. The level of NR2C mRNA is increased in the granule layer of cerebellum in only Rg1 but not Rc infused rats. These results show that structure difference of ginsenoside may diversely affect the modulation of expression of NMDA receptor subunit mRNA after infusion into cerebroventricle in rats.

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A Study of the Effect of Degree of Cure on the Physical Properties of Rubber Compounds (가교정도에 따른 고무복합체의 물리적 특성에 관한 연구)

  • Kim, Hyeon-Jae;Kaang, Shin-Young;Nah, Chang-Woon
    • Elastomers and Composites
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    • v.33 no.4
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    • pp.281-289
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    • 1998
  • Tensile properties including Young's modulus and tear strength were measured for four different rubber compounds; natural rubber(NR), styrene-butadiene copolymer(SBR), ethylene-propylene diene monomer (EPDM), and brominated isobutylene-p-methyl-styrene copolymer(BIMS) as a function of temperature and degree of cure. To see the effect of over cure, a measurement was made of the tensile strength and swelling behavior of the over-cured rubber compounds. Young's modulus, E, was found to have linear dependency on the degree of cure for all rubber compounds. EPDM and BIMS showed the highest and lowest slopes, respectively. The slope of NR and SBR lay between EPDM and BIMS. Tear strength, Gc, decreased in the order of NR>BIMS>SBR>EPDM. As the cure time was extended the degree of cure of NR and SBR decreased, while that of BIMS increased. EPDM showed little change in the degree of cure.

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Noise Reduction Method in consideration of bandwidth of Low Pass Filter (저역통과 필터의 대역폭을 고려한 잡음 제거 방법)

  • Yang, Jeong-Ju;Jang, Won-Woo;Kwak, Boo-Dong;Kang, Bong-Soon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.157-159
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    • 2010
  • Most digital cameras apply a Charge Coupled Device(CCD) Sensor or a Complementary Metal Oxide Semiconductor(COMS) Sensor. And the images captured these sensors include unwanted noises. In this paper, we proposed a method of the Noise Reduction(NR) about noise reduction or recovery in the image. The proposed NR method is related to Bandwidth of the Low Pass Filter(LPF). For improvement of NR, we were changing the filter coefficient of the LPF. The results of simulations with various filter coefficients, [1 2 1] in the LPF and [-1 2 -1] in the High Pass Filter(HPF) have ideal frequency bandwidth and high performance. We proposed a filter coefficient [1 2 1] and [-1 2 -1] in the LPF and the HPF respectively.

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Mechanical Properties of Organoclay filled NR/BR Blends (Organoclay로 보강된 NR/BR Blends의 기계적 특성)

  • Kim, W.;Kim, S.K.;Kim, S.K.;Chuug, K.H.;Byun, J.Y.
    • Elastomers and Composites
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    • v.39 no.1
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    • pp.51-60
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    • 2004
  • The cure, viscoelastic and mechanical characteristics of organoclay filled NR/BR blends were studied and compared with the properties of carbon black and silica filled NR/BR blends. The nanocomposites with extensive exfoliation state can be fabricated by a solution mixing method. In the composites, the amount of filler content was fixed to 10 phr. Degree of intercalation and exfoliation was characterized by X-ray diffraction (XRD). XRD results indicated exfoliation of the silicate layers into the rubber matrix. While the degree or intercalation and exfoliation is lowered by the conventional mixing method, extensive exfoliation can be obtained by the solution mixing method. It was found that the clay filled NR/BR compound showed better viscoelastic (tan ${\delta}$) and mechanical properties than the carbon black or silica filled NR/BR compounds.

Measurement of Thermal Shrinkage/Expansion Force of Filled Rubber (충전된 고무재료의 열변화에 따른 수축력/팽창력 측정)

  • Park, Sang-Min;Hong, Chang-Kook;Cho, Dong-Lyun;Kaang, Shin-Young
    • Elastomers and Composites
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    • v.42 no.4
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    • pp.201-208
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    • 2007
  • In this study, the thermal shrinkage and expansion stresses of filled NR and SBR vulcanizates were measured to investigate the dimensional stability at an elevated temperature. When a rubber sample was held at constant pre-strain, a thermal stress developed upon heating due to the entropic consideration. The peak shrinkage stress of carbon black or silica filled NR decreased with increasing filler content. In SBR compounds, however, the peak shrinkage stress of SBR with 30 phr filler content was higher than that of unfilled compounds. The expansion stress of carbon black filled NR was changed little, but that of filled SBR increased with increasing the filler content. The peak expansion stress of silica filled NR and SBR vulcanizates increased with increasing silica content.