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Light-emitting diode

Troy A Skwor, Stephanie Klemm, Hanyu Zhang, Brianna Schardt, Stephanie Blaszczyk, Matthew A Bork
Increasing rates of antibiotic resistance coupled with the lack of novel antibiotics threatens proper clinical treatment and jeopardizes their use in prevention. A photodynamic approach appears to be an innovative treatment option, even for multi-drug resistant strains of bacteria. Three components are utilized in photodynamic inactivation: a photosensitizer, light source, and oxygen. Variations in photosensitizers strongly influence microbial binding and bactericidal activity. In this study, four different cationic metalloporphyrins (Cu(2+), Fe(2+), Pd(2+), Zn(2+)) were compared to the free-base ligand 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin regarding their electronic properties and generation of reactive oxygen species upon subsequent 405nm violet-blue irradiation...
October 15, 2016: Journal of Photochemistry and Photobiology. B, Biology
Igor S Sidorov, Roman V Romashko, Vasily T Koval, Rashid Giniatullin, Alexei A Kamshilin
We recently pointed out the important role of dermis deformation by pulsating arterial pressure in the formation of a photoplethysmographic signal at green light. The aim of this study was to explore the role of this novel finding in near-infrared (NIR) light. A light-emitting diode (LED)-based imaging photoplethysmography (IPPG) system was used to detect spatial distribution of blood pulsations under frame-to-frame switching green and NIR illumination in the palms of 34 healthy individuals. We observed a significant increase of light-intensity modulation at the heartbeat frequency for both illuminating wavelengths after a palm was contacted with a glass plate...
2016: PloS One
Jiajia Li, Chunlai Ding, Zhengbiao Zhang, Xiangqiang Pan, Na Li, Jian Zhu, Xiulin Zhu
Butyl acrylate is polymerized in the living way under the irradiation of purple light-emitting diode (LED) or sunlight without photocatalyst at ambient temperature. 2-((Phenoxycarbonothioyl)thio) ethyl propanoate) is exclusively added and acted as an initiator and a chain transfer agent simultaneously in the current system. Poly(butyl acrylate) with well-regulated molecular weight and relatively narrow molecular weight distribution (Ð < 1.30) is synthesized. High conversion (>95%) can be achieved within several minutes...
October 21, 2016: Macromolecular Rapid Communications
A C Shortall, R B Price, L MacKenzie, F J T Burke
Light curing is a critical step in the restorative process when using light-activated resin-based composites, but it is frequently not given the attention it deserves. The selection of a reliable light curing unit (LCU) that meets the practitioner's needs is an important equipment purchase. Using an inappropriate LCU may seriously compromise the quality of care without the practitioner realising their mistake until years later. The importance of the subject is reflected by the rapidly increasing use of light-cured composites and the decline in the use of amalgam...
October 21, 2016: British Dental Journal
Amer Z Nahas, Said A Samara, Tannaz A Rastegar-Lari
The aim of this study was to evaluate the effect of low-level light therapy using light-emitting diodes (LEDs) on the speed of tooth movements that were required for the leveling and aligning of the lower anterior segment during non-extraction orthodontic treatment. The sample was comprised of patients (n = 40) with lower anterior crowding who were treated with self-ligating orthodontic brackets and a standardized wire sequence. A test group of patients (n = 20) who were treated with extraoral infrared light therapy for 20 min daily with at least 80 % compliance was compared to a control group (n = 20)...
October 20, 2016: Lasers in Medical Science
Balakrishnan Nirmal
Management of periungual wart is a great challenge, especially when there is subungual extension. The major cause of recurrence of wart is improper clinical assessment of its extent and not directing therapy against the entire wart. This difficulty of ascertaining its extent could be overcome with this finger-shaped red light emitting diode device. Red light in the device penetrates the thick palmar skin and dark constitutive skin colour due to its longer wavelength.
July 2016: Journal of Cutaneous and Aesthetic Surgery
Jonathan B Gillespie, Michelle Maclean, Martin J Given, Mark P Wilson, Martin D Judd, Igor V Timoshkin, Scott J MacGregor
OBJECTIVE: This study investigates possible advantages in pulsed over continuous 405-nm light-emitting diode (LED) light for bacterial inactivation and energy efficiency. BACKGROUND: Alternative nonantibiotic methods of disinfection and infection control have become of significant interest. Recent studies have demonstrated the application of systems using 405-nm LEDs for continuous disinfection of the clinical environment, and also for potential treatment of contaminated wounds...
October 19, 2016: Photomedicine and Laser Surgery
Xiaoyu Zhang, Chun Sun, Yu Zhang, Hua Wu, Changyin Ji, Yahui Chuai, Peng Wang, Shanpeng Wen, Chunfeng Zhang, William W Yu
The high photoluminescence efficiency, high color purity, and easy tunable bandgap make inorganic perovskite nanocrystals very attractive in luminescent display applications. Here, we report a color-saturated, red light-emitting diode (LED) using an inverted organic/inorganic hybrid structure and perovskite nanocrystals. We demonstrated that through a simple post treatment to the perovskite nanocrystals with polyethylenimine, the surface defects of the perovskite nanocrystals could be well passivated, leading to great enhancements on their absolute photoluminescence quantum yield and photoluminescence lifetime...
October 19, 2016: Journal of Physical Chemistry Letters
Takayo Miyakogawa, Genta Kanai, Ryoko Tatsumi, Hiroo Takahashi, Kaichiro Sawada, Takatoshi Kakuta, Masafumi Fukagawa
BACKGROUND: Feasibility of photodynamic therapy (PDT) for secondary hyperparathyroidism (SHPT) was examined in a rat model of SHPT. METHODS: A photosensitizer, 5-aminolevulinic acid (5-ALA), was injected intraperitoneally, and the parathyroid glands were irradiated either after surgical exposure with 385-nm light or transdermally with 630-nm light from a light-emitting diode (LED) lamp. RESULTS: PDT with high 5-ALA and irradiation doses caused severe hypoparathyroidism in SHPT rats within two days...
October 18, 2016: Clinical and Experimental Nephrology
Yang-Seok Yoo, Jong-Ho Na, Sung Jin Son, Yong-Hoon Cho
A critical issue in GaN-based high power light-emitting diodes (LEDs) is how to suppress the efficiency droop problem occurred at high current injection while improving overall quantum efficiency, especially in conventional c-plane InGaN/GaN quantum well (QW), without using complicated bandgap engineering or unconventional materials and structures. Although increasing thickness of each QW may decrease carrier density in QWs, formation of additional strain and defects as well as increased built-in field effect due to enlarged QW thickness are unavoidable...
October 19, 2016: Scientific Reports
Teklay Gebrecherkos, Baye Gelaw, Belay Tessema
BACKGROUND: In correctional settings tuberculosis is a public health concern. The incarcerated population is at greater risk for tuberculosis (TB) than the general population. The aim of this study was to determine the prevalence of smear positive pulmonary tuberculosis (PTB) and associated risk factors in prison settings. METHODS: A cross-sectional study was conducted among prisoners of North Gondar zone where all inmates with a history of cough for ≥ 2 weeks were included...
October 18, 2016: BMC Public Health
Michael R Hamblin
Photobiomodulation (PBM) describes the use of red or near-infrared light to stimulate, heal, regenerate, and protect tissue that has either been injured, is degenerating, or else is at risk of dying. One of the organ systems of the human body that is most necessary to life, and whose optimum functioning is most worried about by humankind in general, is the brain. The brain suffers from many different disorders that can be classified into three broad groupings: traumatic events (stroke, traumatic brain injury, and global ischemia), degenerative diseases (dementia, Alzheimer's and Parkinson's), and psychiatric disorders (depression, anxiety, post traumatic stress disorder)...
December 2016: BBA Clinical
A Krigel, M Berdugo, E Picard, R Levy-Boukris, I Jaadane, L Jonet, M Dernigoghossian, C Andrieu-Soler, A Torriglia, F Behar-Cohen
To save energy, the European directives from the Eco-design of Energy Using Products (2005/32/CE) has recommended the replacement of incandescent lamps by more economic devices such as Light Emitting Diodes (LEDs). However, the emission spectrum of these devices is enriched in blue radiations, known to be potentially dangerous to the retina. Recent studies showed that light exposure contribute to the onset of early stages of Age related macular degeneration (AMD). Here, we investigate, in albinos and pigmented rats, the effects of different exposure protocols...
October 14, 2016: Neuroscience
Yoichiro Nakano, Takashi Yanase, Taro Nagahama, Hajime Yoshida, Toshihiro Shimada
The water vapor transmission rate (WVTR) of a gas barrier coating is a critically important parameter for flexible organic device packaging, but its accurate measurement without mechanical stress to ultrathin films has been a significant challenge in instrumental analysis. At the current stage, no reliable results have been reported in the range of 10(-6) g m(-2) day(-1) that is required for organic light emitting diodes (OLEDs). In this article, we describe a solution for this difficult, but important measurement, involving enhanced sensitivity by a cold trap, stabilized temperature system, pumped sealing and calibration by a standard conductance element...
October 17, 2016: Scientific Reports
Nikolai Blanik, Konrad Heimann, Carina Pereira, Michael Paul, Vladimir Blazek, Boudewijn Venema, Thorsten Orlikowsky, Steffen Leonhardt
Vital parameter monitoring of term and preterm infants during incubator care with self-adhesive electrodes or sensors directly positioned on the skin [e.g. photoplethysmography (PPG) for oxygen saturation or electrocardiography (ECG)] is an essential part of daily routine care in neonatal intensive care units. For various reasons, this kind of monitoring contains a lot of stress for the infants. Therefore, there is a need to measure vital parameters (for instance respiration, temperature, pulse, oxygen saturation) without mechanical or conductive contact...
October 15, 2016: Biomedizinische Technik. Biomedical Engineering
Ming Dai, Xueliang Xiao, Xin Chen, Haoming Lin, Wanqing Wu, Siping Chen
With the increasing aging population as well as health concerns, chronic heart disease has become the focus of public attention. A comfortable, low-powered, and wearable electrocardiogram (ECG) system for continuously monitoring the elderly's ECG signals over several hours is important for preventing cardiovascular diseases. Traditional ECG monitoring apparatus is often inconvenient to carry, has many electrodes to attach to the chest, and has a high-power consumption. There is also a challenge to design an electrocardiograph that satisfies requirements such as comfort, confinement, and compactness...
October 14, 2016: Australasian Physical & Engineering Sciences in Medicine
Man-Keung Fung, Yan-Qing Li, Liang-Sheng Liao
A tandem organic light-emitting diode (OLED) is an organic optoelectronic device that has two or more electroluminescence (EL) units connected electrically in series with unique intermediate connectors within the device. Researchers have studied this new OLED architecture with growing interest and have found that the current efficiency of a tandem OLED containing N EL units (N > 1) should be N times that of a conventional OLED containing only a single EL unit. Therefore, this new architecture is potentially useful for constructing high-efficiency, high-luminance, and long-lifetime OLED displays and organic solid-state lighting sources...
October 13, 2016: Advanced Materials
Hongjian Li, Panpan Li, Junjie Kang, Jiianfeng Ding, Jun Ma, Yiyun Zhang, Xiaoyan Yi, Guohong Wang
We have presented broadband full-color monolithic InGaN light-emitting diodes (LEDs) by self-assembled InGaN quantum dots (QDs) using metal organic chemical vapor deposition (MOCVD). The electroluminescence spectra of the InGaN QDs LEDs are extremely broad span from 410 nm to 720 nm with a line-width of 164 nm, covering entire visible wavelength range. A color temperature of 3370 K and a color rendering index of 69.3 have been achieved. Temperature-dependent photoluminescence measurements reveal a strong carriers localization effect of the InGaN QDs layer by obvious blue-shift of emission peak from 50 K to 300 K...
October 13, 2016: Scientific Reports
Xiaofei Zhao, Baohua Zhang, Ruyan Zhao, Bing Yao, Xuejing Liu, Jun Liu, Zhiyuan Xie
Organometal halide perovskites (OHPs) are becoming a hot topic in the field of display and lighting. Unlike strategy used for solar cells, i.e. using several hundred nanometer thick OHP film for fully absorbing solar light to convert electricity, thin film OHPs (less than 50 nm) are advantageous to restrain its self-absorption drawback and thus beneficial for preparing efficient light-emitting diodes (LEDs). Here, we manipulate the excess molar ratio of MABr:PbBr2 precursors and the post annealing temperature to obtain uniform thin film OHPs and suppress the nonradiative defects...
October 13, 2016: Journal of Physical Chemistry Letters
Yang Wang, Yaoming Lu, Baoxiang Gao, Shumeng Wang, Junqiao Ding, Lixiang Wang, Xiabin Jing, Fosong Wang
A novel self-host blue-emitting iridium dendrimer, namely B-CzPO, has been designed and synthesized via a post-dendronization route, where a bipolar carbazole/triphenylphosphine oxide hybrid is selected as the peripheral dendron instead of the p-type oligocarbazole used in the unipolar analogue B-CzG2. This structural modification can render B-CzPO with more balanced charge transportation relative to B-CzG2. As a result of the significantly reduced efficiency roll-off, the nondoped phosphorescent organic light-emitting diodes (PhOLEDs) of B-CzPO show a superior high-brightness performance, revealing a luminous efficiency of 21...
October 13, 2016: ACS Applied Materials & Interfaces
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