• Title/Summary/Keyword: Visible Light

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The Effects of Visible Light on Iron Release from Ferritin Related to Lipid Peroxidation in the Retina

  • Ohishi, Kentaro;Hiramitsu, Tadahisa;Matsugo, Seiichi
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.427-429
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    • 2002
  • We studied iron release from ferritin by irradiating the visible light, and then followed ferritin-mediated lipid peroxidation in the rod outer segment (ROS) fraction of the porcine retina. In the presence of several phosphorus compounds such as ADP and ATP, iron release from ferritin at pH 7.0 could be induced by irradiation of the visible light to the reaction mixtures. Furthermore, iron release from ferritin in the presence of ADP depended on the incubation time and the visible light irradiation. Moreover, we investigated lipid peroxidation level in the ROS fraction by two independent assay systems including the thiobarbituric acid (TBA) and ferrous oxidation/xylenol orange (FOX) methods. The visible light induced ferritin-mediated lipid peroxidation in the ROS fraction in time- and irradiance-dependent manners. In the dark condition, iron release and lipid peroxidation were not observed. Iron release from ferritin by irradiating the visible light may play an important role in the etiology of phototoxic injuries in vivo.

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Modeling Green-light Fiber Amplifiers for Visible-light Communication Systems

  • Khushik, Muhammad Hanif Ahmed Khan;Jiang, Chun
    • Current Optics and Photonics
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    • v.3 no.2
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    • pp.105-110
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    • 2019
  • The visible-light communication (VLC) system is a promising candidate to fulfill the present and future demands for a high-speed, cost-effective, and larger-bandwidth communication system. VLC modulates the visible-light signals from solid-state LEDs to transmit data between transmitter and receiver, but the broadcasting and the line-of-sight propagation nature of visible-light signals make VLC a communication system with a limited operating range. We present a novel architecture to increase the operating range of VLC. In our proposed architecture, we guide the visible-light signals through the fiber and amplify the dissipated signals using visible-light fiber amplifiers (VLFAs), which are the most important and the novel devices needed for the proposed architecture of the VLC. Therefore, we design, analyze, and apply a VLFA to VLC, to overcome the inherent drawbacks of VLC. Numerical results show that under given constant conditions, the VLFA can amplify the signal up to 35.0 dB. We have analyzed the effects of fiber length, active ion concentration, pump power, and input signal power on the gain and the noise figure (NF).

Photocatalyst Effect of Polyester Fabrics Treated with Visible-light Responsive Photocatalyst

  • Choi, Sei Young
    • Elastomers and Composites
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    • v.51 no.1
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    • pp.31-37
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    • 2016
  • In this study, we studied the photocatalytic functionality such as deodorant, antibacterial, antistatic of polyester fabrics treated with visible-light responsive photocatalyst. According to UV/visible spectrometry result, the UV-visible peak of visible-light responsive photocatalyst was found to be red shift at 420 nm sensitive in the visible light region. Also, the deodorizing and antimicrobial performance were shown to be retained more than 99% both before washing and even after 25 times washing. According to washing durability of polyester fabrics treated with visible-light responsive photocatalyst, the reduction effects for gas such as ammonia, trimethylamine, formaldehyde and toluene after 25 times washing appeared to be retained as much as before washing. At both before washing and after 25 times washing, antistatic property showed frictional voltage of approximately 250V.

A Study on the Reduction of VOCs Generated from Vehicle Interior Parts and Materials Using Visible-light Responsive Photocatalyst (가시광촉매를 이용한 자동차 내장재로부터 발생하는 VOCs의 저감연구)

  • Choi, Sei-Young;Yang, Seung-Gi
    • Elastomers and Composites
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    • v.48 no.3
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    • pp.209-215
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    • 2013
  • On this study, visible-light responsive photocatalyst prepared by sol-gel method was evaluated the effect of the reduction of volatile organic compounds (VOCs) occurred in vehicle interior and its property was examined. According to UV/visible result, visible-light responsive photocatalyst was found that the UV-visible peak is red shift at 420nm, is sensitive in the visible light region. With vehicle interior parts and materials coated visible-light responsive photocatalyst, VOCs was measured by GC/MS. Measuring the VOCs generated from vehicle interior parts and materials, the reduction of VOCs was confirmed.

VOCs Reduction of Visible-light Responsive Photocatalyst coated nylon/polyester composite fiber for Vehicle Interior Parts and Materials (가시광 감응형 광촉매가 코팅처리된 자동차내장재용 Nylon/Polyester 복합섬유의 VOCs 저감)

  • Choi, Sei-Young
    • Elastomers and Composites
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    • v.49 no.1
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    • pp.53-58
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    • 2014
  • In this study, characteristics of visible-light responsive photocatalyst Weltouch, especially VOCs reduction of visible-light responsive photocatalyst coated nylon/polyester composite fiber for vehicle interior parts and materials were evaluated. Visible-light responsive photocatalyst Weltouch was observed for both anatase phase and rutile phase. It is activated by light longer than 420nm. VOCs and formaldehyde generated from visible-light responsive photocatalyst treated nylon/polyester composite fiber were reduced confirmly. Visible-light responsive photocatalyst was firmly attached to the surface of nylon/polyester composite fiber without elimination even after 25 times repeated washing. And washing durability of nylon/polyester composite fiber confirmed the excellence that reduction effects of VOCs after repeated washing has appeared as much as before washing.

LED Illumination Infrastructure for Ubiquitous Society based on the Visible Light Communication (가시광통신 기반 u-Society 구현을 위한 LED 조명 인프라)

  • Jeon, Jeong-U
    • 한국정보통신설비학회:학술대회논문집
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    • pp.273-276
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    • 2008
  • This article describes a LED illumination infrastructure for ubiquitous society based on the Visible Light Communication technology. The VLC is one of the advanced communication system using "Visible Light". The VLC system has a lot of advantageous features and can be used in various places for the next future generation. So, we analyzed ubiquitous service model based on the VLC system and some applications. And we renewed discussion about LED illumination infrastructure for u-Society.

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Visible Light Communication LED driver For research to improve power (가시통신용 LED 드라이버 전력 효율 성능 향상을 위한 연구)

  • Kwon, Jae-hyun;Park, Keon-jun;Kim, Hyo-jun;Choi, Gil-Sang;Kim, Young-kab
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.15-16
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    • 2012
  • General lighting will be replaced into LED due to the high efficiency, low power consumption, long life than conventional light, moreover, since it is a basically semiconductor device that can convert the electric energy to visible light at a very high speed, using these characteristics can be performed communication modulation via the high-speed ON-OFF switching. Recently, visible light communication (VLC: Visible Light Communication) technology is received attention and there have been many researches. This paper is implemented media signal transmission by combining LED with VLC, a transmitter used the LED light-emitting device and receiver used an infrared sensor. In order to increase the efficiency of the communication system to improve the existing LED visible light communication driver of power conversion efficiency and thermal issues that is applied to the visible light communication in order to improve the speed of transmission media to research a new way of LED driver.

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Visible-light Photocatalytic Activity of BiOCl/Bi3O4Cl Nanocomposites

  • Gao, Bifen;Chakraborty, Ashok Kumar;Yang, Ji-Min;Lee, Wan-In
    • Bulletin of the Korean Chemical Society
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    • v.31 no.7
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    • pp.1941-1944
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    • 2010
  • The heterojunction structures of BiOCl/$Bi_3O_4Cl$, exhibiting considerable visible-light photocatalytic efficiency, were prepared by a simple wet-chemical process at ambient condition. The prepared nanocomposites were characterized by XRD, TEM, and UV-visible diffuse reflectance spectra. Under visible light (${\lambda}\geq$420 nm) irradiation, BiOCl/$Bi_3O_4Cl$ exhibited an enhanced photocatalytic activity in decomposing 2-propanol (IP) in gas phase and salicylic acid (SA) in aqueous solution, whereas the bare BiOCl and $Bi_3O_4Cl$ showed negligible activities. It is deduced that the remarkable visible-light photocatalytic activity of the BiOCl/$Bi_3O_4Cl$ originates from the hole $(h^+)$ transfer between VB of the $Bi_3O_4Cl$ and BiOCl semiconductors.

Localization Techniques Based on Image Sensor and Visible Light Communication (이미지 센서 및 가시광 통신 기반 위치 추정 기술)

  • Le, Nam-Tuan;Ifthekhar, Md. Shareef;Mondal, Ratan Kumar;Jang, Yeong Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.1
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    • pp.37-41
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    • 2016
  • Localization is one of the key issues of demandable applications, especially smart services. Beside the traditional GPS based localization technique, the localization issue by visible light communications is promising market because of possibility of combining visible light communications with positioning technique for a high accurate, especially indoor localization service. This paper provides the overview and new image sensor scheme for localization issue based on visible light communication. The survey is introduced from core techniques to enhancement issues of localization. We hope these will be the essential references for the impact selection method in implementation and standardization issues.

Flicker Prevention Through Edge-Pulse Modulation in a Visible Light Identification System (가시광 무선인식장치에서 가장자리 펄스변조를 이용한 플리커 방지)

  • Lee, Seong-Ho
    • Journal of Sensor Science and Technology
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    • v.29 no.3
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    • pp.180-186
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    • 2020
  • In this study, we applied edge-pulse modulation to prevent the flicker of light-emitting diode (LED) light in a visible light identification system. In the visible light transmitter, positive pulses were transmitted at the edges of the low-to-high transition points, and negative pulses were transmitted at the edges of the high-to-low transition points of the non-return-to-zero (NRZ) data waveforms. In the visible light receiver, the NRZ waveforms were regenerated by making low-to-high and high-to-low transitions at the point of the positive and negative pulses, respectively. This method has two advantages. First, it ensures that the LED light is flicker-free because the average optical power of the LED was kept constant during data transmission in the transmitter. Second, the 120 Hz optical noise from the adjacent lighting lamps was easily cut off using a simple RC-high pass filter in the receiver.