• Title, Summary, Keyword: UV wavelength

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The Study of DEP Degradation Properties by Combination US and UV Lamp of Different Wavelength (초음파 (US)와 다양한 파장범위의 자외선 (UV) 조사에 따른 DEP 분해특성에 관한 연구)

  • Na, Seung-Min;Cai, Jinhua;Shin, Dong-Hoon;Cui, Mingcan;Khim, Jee-Hyeong
    • Journal of Environmental Science International
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    • v.21 no.7
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    • pp.845-853
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    • 2012
  • Diethyl phthalate (DEP) is widely spread in the natural environment as an endocrine disruption chemicals (EDs). Therefore, in this study, ultrasound (US) and ultraviolet (UVC), including various applied power density (10-40 W/L), UV wavelengths (365 nm, 254 nm and 185 nm) and frequencies (283 kHz, 935 kHz) were applied to a DEP contaminated solution. The pseudo-first order degradation rate constants were in the order of $10^{-1}$ to $10^{-4}\;min^{-1}$ depending on the processes. Photolytic and sonophotolytic DEP degradation rate also were high at shortest UV wavelength (VUV) due to the higher energy of photons, higher molar absorption coefficient of DEP and increased hydroxyl radical generation from homolysis of water. Sonolytic DEP degradation rate increased with increase of applied input power and the dominant reaction mechanism of DEP in sonolysis was estimated as hydroxyl radical reaction by the addition of t-BuOH, which is a common hydroxyl radical scavenger. Moreover, synergistic effect of were also observed for sonophotolytic degradation with various UV irradiation.

Radiation Effects on Fiber Bragg Grating Sensors by Irradiation Conditions of UV Laser (UV 레이저 노출조건에 따른 FBG 센서의 방사선 영향)

  • Kim, Jong-Yeol;Lee, Nam-Ho;Jung, Hyun-Kyu
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.12
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    • pp.2310-2316
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    • 2016
  • We studied the effect of $Co^{60}$ gamma-radiation on the fiber Bragg gratings (FBGs) by irradiation time of UV Krypton fluoride (KrF) excimer laser among grating processing parameters. The FBGs were fabricated in a different UV laser irradiation time at 30, 60, 90, and 120 seconds using the same commercial Ge-doped silica core fiber (SMF-28e). It was exposed to gamma-radiation up to a high dose of 34.3 kGy at the dose rate of 106 Gy/min, and then it was analyzed radiation effects by measuring the radiation-induced change in the temperature sensitivity coefficient and Bragg wavelength shift. According to the experimental results, We confirmed that the UV laser irradiation period for grating inscription has a highly effect on the radiation sensitivity of the FBGs. The radiation-induced Bragg wavelength shift by the change of laser irradiation conditions showed a difference more than about 50 %.

Tone-on-tone Dyeing of PET Fabrics Using Selective UV Irradiation and Cationic Dyes (선택적 UV 조사와 캐티온 염료를 이용한 PET 직물의 톤온톤 염색)

  • Son, Jung-A;Jang, Jin-Ho
    • Textile Science and Engineering
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    • v.44 no.3
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    • pp.142-148
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    • 2007
  • PET fabrics were irradiated by a UV irradiator containing a mercury lamp. The UV-irradiated PET was photo-oxidized by both UV light and ozone and nano-scale roughness was produced on the PET surface. The irradiated PET became less reflective in a visible wavelength region below 450 nm and the zeta potential of the irradiated PET fabric decreased to be more negative compared with that of the pristine PET. The surface modified PET fabric were colored with two cationic dyes. The dyeability of UV treated side increased proportionally with increasing UV energy in comparison with the unirradiated side. Various tone-on-tone patterns were obtained by one-bath dyeing based on the enhanced dyeability of UV-irradiated area on the PET, which is proportional to the UV energy.

Brilliantly Shining Semiconductor Nanocrystal Dispersed Glass for UV-LED Excitation

  • Murase, Norio;Li, Chunliang
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.385-387
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    • 2003
  • We have fabricated a new-type high-brightness phosphor consisting of a sol-gel derived glass with finely dispersed semiconductor nanocrystals. It is possible to obtain visible light of any wavelength with a single UV irradiation. The glass firmly adheres to a glass substrate. Therefore it can easily be used for developing devices.

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Antiapoptotic Effects Induced by Different Wavelengths of Ultraviolet Light

  • Ibuki, Yuko;Goto, Rensuke
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.485-487
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    • 2002
  • Cells receive signals for survival as well as death, and the balance between the two ultimately determines the fate of the cells. UV-triggered apoptotic signaling has been well documented, whereas UV-induced survival effects have received little attention. We have reported previously that UVB irradiation prevented apoptosis, which was partly dependent on activation of the phosphatidylinositol 3-kinase (PI3-kinase)/ Akt pathway. In this study, anti-apoptotic effects of UV with different wavelength ranges, UVA, UVB and UVC, were examined. NIH3T3 cells showed apoptotic cell death by detachment from the extracellular matrix under serum-free conditions, which was prevented by all wavelengths. However, the effect of UVA was less than those of UVB and UVC. Reduction of mitochondrial transmembrane potential and activation of caspase-9 and -3 were suppressed by all three wavelengths of UV, showing wavelength-dependent effects as mentioned above. The PI3-kinase inhibitor wortmannin partially inhibittrl the UVB and UVC-induced suppression of apoptosis, but not the inhibitoty effect of UVA. The Akt phosphotylation by UVB and UVC was completely inhibittrl by addition of wortmannin, but that by UVA was not P38 MAP kinase inhibitor SB203580 partially inhibited the UVB and UVC-induced suppression of apoptosis and Akt phosphotylation, and completely inhibited UVA-induced those. These results suggested the existence of two different survival pathways leading to suppression of apoptosis, one for UVA that is independent of the PI3-kinase/Akt pathway and dependent on p38 MAP kinase, and the other for UVB and UVC that is dependent on both pathways.

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Identification of Buza by Detecting Aconitine-type Alkaloids (Aconitine 류 알칼로이드의 검출에 의한 부자류 생약의 확인)

  • Eom, Dong-Ok;Ban, Tae-Hwan
    • Analytical Science and Technology
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    • v.12 no.3
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    • pp.243-247
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    • 1999
  • After aconitine-type alkaloids have been isolated from the crude drug "Buza" as the precipitate, they could be identified with colour test, UV/Vis. absorption wavelength, TLC. The presence of aconitine-type alkaloids are confirmed by the reaction with the Reineke ion, $[Cr(NH_3)_2(SCN)_4]^{1+}$, and TCR ion, $[Co(SCN)4]^{2-}$, to produce the white precipitate or one of the containing from blue to yellowish blue. It is based on the formation of complex compounds by aconitine-type alkaloids with Reineke and TCR reagent. The method has been found to be simple, convenient and suitable for routine identification of aconitine-type alkaloids, related basic compounds, the crude drug "Buza" processed from the roots of certain Aconitum spp. plants(Ranunculaceae).

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Photodegradation of Gaseous Toluene Using Short-Wavelength UV/TiO2 and Treatment of Decomposition Products by Wet Scrubber (단파장자외선/TiO2 공정에 의한 가스상 톨루엔의 분해 및 습식세정장치에 의한 분해생성물의 제거)

  • Jeong, Ju-Young;Jurng, Jong-Soo
    • Journal of Environmental Science International
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    • v.16 no.4
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    • pp.433-440
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    • 2007
  • The photodegradation and by-products of the gaseous toluene with $TiO_2$ (P25) and short-wavelength UV ($UV_{254+185nm}$) radiation were studied. The toluene was decomposed and mineralized efficiently owed to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the $TiO_2$ surface. The toluene by the $UV_{254+185nm}$ photoirradiated $TiO_2$ were mainly mineralized $CO_2$ and CO, but some water-soluble organic intermediates were also formed under severe reaction conditions. The ozone and secondary organic aerosol were produced as undesirable by-products. It was found that wet scrubber was useful as post-treatment to remove water-soluble organic intermediates. Excess ozone could be easily removed by means of a $MnO_2$ ozone-decomposition catalyst. It was also observed that the $MnO_2$ catalyst could decompose organic compounds by using oxygen reactive species formed in process of ozone decomposition.

Effect of PVAm Application for Fine Paper on Effectiveness of Optical Brightening Agent (PVAm 적용이 백상지의 형광증백제 발현효율에 미치는 영향)

  • Cho, Byoung-Uk;Won, Jong Myoung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.48 no.3
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    • pp.23-29
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    • 2016
  • Effects of cationic polyvinylamine (PVAm) dry strength agent on effectiveness of optical brightening agent (OBA) during fine papermaking and the mechanism for brightness reduction of paper by PVAm was investigated by UV/Vis spectroscopy and turbidity measurement of OBA solution with PVAm. It was shown that PVAm reduced brightness of paper while opacity was not varied and tensile strength of paper was increased. Tetra-type OBA solution showed the peaks around the wavelength of 280 nm and 330 nm and the increase in the OBA concentration increased the UV absorbance in all wavelength. Addition of PVAm into the OBA solution decreased the UV absorbance at 280 nm. Turbidities of OBA and PVAm solutions were close to zero, respectively, while the turbidity value increased for the mixed solution of OBA and PVAm in various mixing ratios and the highest value was obtained when the mixing ratio of PVAm and OBA was 5:5, meaning that cationic PVAm formed complex with anionic OBA. In conclusion, cationic PVAm could form a complex with anionic OBA and that reduced UV absorbance, resulting in the reduced brightness of paper.

Preparation of Ba2Mg(PO4)2:Eu Phosphors and Their Photoluminescence Properties Under UV Excitation (Ba2Mg(PO4)2:Eu 형광체의 합성과 자외선 여기하의 발광특성)

  • Tae, Se-Won;Jung, Ha-Kyun;Choi, Sung-Ho;Hur, Nam-Hwi
    • Korean Journal of Materials Research
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    • v.18 no.11
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    • pp.623-627
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    • 2008
  • For possible applications as luminescent materials for white-light emission using UV-LEDs, $Ba_2Mg(PO_4)_2:Eu^{2+}$ phosphors were prepared by a solid state reaction. The photoluminescence properties of the phosphor were investigated under ultraviolet ray (UV) excitation. The prepared phosphor powders were characterized to from a single phase of a monoclinic crystalline structure by a powder X-ray diffraction analysis. In the photoluminescence spectra, the $Ba_2Mg(PO_4)_2:Eu^{2+}$ phosphor showed an intense emission band centered at the 584 nm wavelength due to the f-d transition of the $Eu^{2+}$ activator. The optimum concentration of $Eu^{2+}$ activator in the $Ba_2Mg(PO_4)_2$ host, indicating the maximum emission intensity under the excitation of a 395 nm wavelength, was 5 at%. In addition, it was confirmed that the $Eu^{2+}$ ions are substituted at both $Ba^{2+}$ sites in the $Ba_2Mg(PO_4)_2$ crystal. On the other hand, the critical distance of energy transfer between $Eu^{2+}$ ions in the $Ba_2Mg(PO_4)_2$ host was evaluated to be approximately 19.3 A. With increasing temperature, the emission intensity of the $Ba_2Mg(PO_4)_2$:Eu phosphor was considerably decreased and the central wavelength of the emission peak was shifted toward a short wavelength.

Ultra Violet (UV) Sensor based on Oxide Ceramic Materials (산화물 세라믹 재료 기반 자외선 센서)

  • Yu, Hak Ki
    • Ceramist
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    • v.22 no.1
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    • pp.27-35
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    • 2019
  • Research on ultraviolet (UV) light detection has attracted considerable attention from scientific researchers in related fields. It can be said that it is a very important time to accurately monitor the UV irradiation amount according to the wavelength region in real time. The oxide is very diverse in its kind and has the advantage of being able to efficiently control the band gap through band gap engineering. In addition, it is very stable in response to heat and atmospheric oxygen when UV is absorbed. Also, there is a known method that can effectively manufacture oxide nanoparticles and nanorods through various synthesis methods, and researches for improving the sensitivity of UV sensors have been carried out using this method. In this paper, we introduce the materials that can be used as UV sensors among various wide band oxide materials, and review the results of researches of various UV sensors using nano materials.