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  1. Alpha-fetoprotein, stem cells and cancer: how study of the production of alpha-fetoprotein during chemical hepatocarcinogenesis led to reaffirmation of the stem cell theory of cancer.

    Science.gov (United States)

    Sell, Stewart

    2008-01-01

    Identification of the cells in the liver that produce alpha-fetoprotein during development, in response to liver injury and during the early stages of chemical hepatocarcinogenesis led to the conclusion that maturation arrest of liver-determined tissue stem cells was the cellular process that gives rise to hepatocellular carcinomas. When the cellular changes in these processes were compared to that of the formation of teratocarcinomas, the hypothesis arose that all cancers arise from maturation arrest of tissue-determined stem cells. This was essentially a reinterpretation of the embryonal rest theory of cancer whereby tissue stem cells take the role of embryonal rests. A corollary of the stem cell theory of the origin of cancer is that cancers contain the same functional cell populations as normal tissues: stem cells, transit-amplifying cells and mature cells. Cancer stem cells retain the essential feature of normal stem cells: the ability to self-renew. Growth of cancers is due to continued proliferation of cancer transit-amplifying cells that do not differentiate to mature cells (maturation arrest). On the other hand, cancer stem cells generally divide very rarely and contribute little to tumor growth. However, the presence of cancer stem cells in tumors is believed to be responsible for the properties of immortalization, transplantability and resistance to therapy characteristic of cancers. Current therapies for cancer (chemotherapy, radiotherapy, antiangiogenesis and differentiation therapy) are directed against the cancer transit-amplifying cells. When these therapies are discontinued, the cancer reforms from the cancer stem cells. Therapy directed toward interruption of the cell signaling pathways that maintain cancer stem cells could lead to new modalities to the prevention of regrowth of the cancer.

  2. Dietary zinc deficiency predisposes mice to the development of preneoplastic lesions in chemically-induced hepatocarcinogenesis.

    Science.gov (United States)

    Romualdo, Guilherme Ribeiro; Goto, Renata Leme; Henrique Fernandes, Ana Angélica; Cogliati, Bruno; Barbisan, Luis Fernando

    2016-10-01

    Although there is a concomitance of zinc deficiency and high incidence/mortality for hepatocellular carcinoma in certain human populations, there are no experimental studies investigating the modifying effects of zinc on hepatocarcinogenesis. Thus, we evaluated whether dietary zinc deficiency or supplementation alter the development of hepatocellular preneoplastic lesions (PNL). Therefore, neonatal male Balb/C mice were submitted to a diethylnitrosamine/2-acetylaminefluorene-induced hepatocarcinogenesis model. Moreover, mice were fed adequate (35 mg/kg diet), deficient (3 mg/kg) or supplemented (180 mg/kg) zinc diets. Mice were euthanized at 12 (early time-point) or 24 weeks (late time-point) after introducing the diets. At the early time-point, zinc deficiency decreased Nrf2 protein expression and GSH levels while increased p65 and p53 protein expression and the number of PNL/area. At the late time-point, zinc deficiency also decreased GSH levels while increased liver genotoxicity, cell proliferation into PNL and PNL size. In contrast, zinc supplementation increased antioxidant defense at both time-points but not altered PNL development. Our findings are the first to suggest that zinc deficiency predisposes mice to the PNL development in chemically-induced hepatocarcinogenesis. The decrease of Nrf2/GSH pathway and increase of liver genotoxicity, as well as the increase of p65/cell proliferation, are potential mechanisms to this zinc deficiency-mediated effect.

  3. Potential role of p53 mutation in chemical hepatocarcinogenesis of rats

    Institute of Scientific and Technical Information of China (English)

    Wei-Guo Deng; Yan Fu; Yu-Lin Li; Toshihiro Sugiyama

    2004-01-01

    AIM: Inactivation of p53 gene is one of the most frequent genetic alterations in carcinogenesis. The mutation status of p53 gene was analyzed, in order to understand the effect of p53 mutation on chemical hepatocarcinogenesis of rats.METHODS: During hepatocarcinogenesis of rats induced by 3′-methyl-4- dimethylaminoazobenzene (3′-Me-DAB),prehepatocarcinoma and hepatocarcinoma foci were collected by laser capture microdissection (LCMl), and quantitatively analyzed for levels of p53 mRNA by LightCyclerTM real-time RT-PCR and for mutations in p53 gene exons 5-8 by direct sequencing.RESULTS: Samples consisting of 44 precancerous foci and 24 cancerous foci were collected by LCMl. A quantitative analysis of p53 mRNA showed that p53 mRNA peaked at an early stage (week 6) in the prehepatocarcinoma lesion, more than ten times that of adjacent normal tissue, and gradually decreased from week 6 to week 24. The expression of p53 mRNA in adjacent normal tissue was significantly lower than that in prehepatocarcinoma. Similar to prehepatocarcinoma,p53 mRNA in cancer was markedly higher than that in adjacent normal tissue at week 12, and was closer to normal at week 24. Direct p53 gene sequencing showed that 35.3% (24/68) (9 precancer, 15 cancer) LCM samples exhibited point mutations, 20.5% of prehepatocarcinoma LCM samples presented missense mutations at exon 6/7 or/and 8, and was markedly lower than 62.5% of hepatocarcinoma ones (P<0.01). Mlutation of p53 gene formed the mutant hot spots at 5 codons. Positive immunostaining for p53 protein could be seen in prehepatocarcinoma and hepatocarcinoma foci at 24 weeks.CONCLUSION: p53 gene mutation is present in initial chemical hepatocarcinogenesis, and the mutation of p53 gene induced by 3′-Me-DAB is an important factor of hepatocarcinogenesis.

  4. Absence of p53 gene expression in selenium molecular prevention of chemically Induced hepatocarcinogenesis in rats

    Directory of Open Access Journals (Sweden)

    Nasar Y Alwahaibi

    2011-01-01

    Full Text Available Background/Aim: p53 pathway is thought by many researchers to be critically involved in selenium′s chemoprevention or in hepatocarcinogenesis. The aim of this study was to investigate the gene expression of p53, p21 and B-cell lymphoma-2 (bcl-2 using preventive and therapeutic approaches of selenium in chemically induced hepatocarcinogenesis in rats. Materials and Methods: Rats were divided randomly into six groups: Negative control, positive control (diethyl nitrosamine +2-acetylaminofluorene, preventive group, preventive control (respective control for preventive group, therapeutic group and therapeutic control (respective control for therapeutic group. p53, p21 and bcl-2 genes on liver tissues were measured using real-time polymerase chain reaction. Results: The expression of p53 was only significant in the therapeutic control. The expression of bcl-2 was insignificant in all the groups. p21 expression was significant in all the groups except the preventive group. Conclusions: The selenium molecular mechanism for liver cancer prevention is not through the p53 pathway. Also, the absence of p53 is not necessary for chemically induced liver cancer in rats.

  5. Suppressive effect of herbal compound 861 on chemical hepatocarcinogenesis in rats

    Institute of Scientific and Technical Information of China (English)

    崔儒涛; 王宝恩; 张福奎; 陈光勇; 尹珊珊

    2003-01-01

    Objective To investigate the effects of herbal compound 861 (Cpd861) on hepatocarcinogenesis induced by diethylntrosamine and 2-acetylaminofluorene (DEN-AAF) in female Sprague Dawley rats.Methods Liver preneoplastic foci were induced using the DEN-AAF method in female Sprague Dawley rats, which were then treated with Cpd861. For quantitative assessment of liver preneoplastic foci, the placental form of glutathione-S-transferase (GST-P) positive foci were measured using immunohistochemical staining and image analysis. GST-P protein expression was measured by Western blotting, mRNA expression was assessed by Northern blotting.Results Treatment using DEN-AAF caused a significant decrease in body weight and increase in liver weight compared to the control group. Oral Cpd861 administration essentially prevented DEN-AAF-induced body weight loss and liver weight increase. When 2-AAF was followed by treatment with Cpd861, there was a decrease in the number of large foci as compared to 2-AAF alone. However, there were still considerable numbers of small mixed clear/vacuolated cell foci, some of which were positive for GST-P. Significant increase in GST-P protein and mRNA expression were observed in the DEN-AAF group, while treatment with Cpd861 inhibited the increase. The effect of Cpd861 on hepatocarcinogenesis occurred in a concentration-dependent manner. Conclusion Chinese herbal compound Cpd861 prevents hepatocarcinogenesis in DEN-AAF-induced liver preneoplastic lesions in rats.

  6. Dietary administration of inositol and/or inositol-6-phosphate prevents chemically-induced rat hepatocarcinogenesis.

    Science.gov (United States)

    Lee, Hae-Jeung; Lee, Sang-Ah; Choi, Haymie

    2005-01-01

    Chemoprevention is considered a rational strategy for dietary approaches to prevention of cancer. Multiple lines of evidence suggest that many of our dietary principles are able to intervene in the multistage carcinogenesis process and phytic acid (inositol hexaphosphate, IP6), a phytochemical present in a variety of plant species, has been shown to prevent various cancers, including those of the mammary gland, colon and liver. However, the mechanism of chemoprevention by IP6 has not been fully elucidated. In the present study, we examined the effects of inositol and/or IP6 supplementation on rat hepatocarcinogenesis initiated by diethylnitrosamine (DEN) and promoted by partial hepatectomy (PH). Supplementation with either inositol or IP6, or their combination, starting one week prior to administration of DEN, resulted in a significant decrease in both the area and the number of placental glutathione S-transferase positive (GST-P+) foci, a preneoplastic marker for DEN-initiated hepatocarcinogenesis. The administration of inositol and/or IP6 in drinking water caused marked enhancement in the glutathione S-transferase (GST) activity. In addition, the production of thiobarbituric acid reactive substances and the catalase activity were significantly reduced in rats supplemented with inositol and /or IP6. Based on these findings, it is likely that the chemopreventive effects of inositol and/or IP6 on rat hepatocarcinogenesis initiated by DEN and promoted by PH are associated with induction of GST activity and suppression of lipid peroxidation.

  7. Inactivation of cyclin E1 inhibits chemically induced hepatocarcinogenesis in mice

    OpenAIRE

    Moro, Nives

    2011-01-01

    E-type cyclins (CcnE) control the transition of quiescent cells into the cell cycle. Two E-type cyclins, CcnE1 and CcnE2 have been described. A variety of human cancers, including hepatocellular carcinoma (HCC), overexpress CcnE and this is frequently associated with reduced patient survival. The aim of the present study was to dissect the role of CcnE1 and CcnE2 for hepatocarcinogenesis induced by the carcinogen diethylnitrosamine (DEN) using CcnE1 and CcnE2 knockout mice. The central questi...

  8. Persistent activation of NF-kappaB related to IkappaB's degradation profiles during early chemical hepatocarcinogenesis

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    García-Román Rebeca

    2007-04-01

    Full Text Available Abstract Background To define the NF-kappaB activation in early stages of hepatocarcinogenesis and its IkappaB's degradation profiles in comparison to sole liver regeneration. Methods Western-blot and EMSA analyses were performed for the NF-kappaB activation. The transcriptional activity of NF-kappaB was determined by RT-PCR of the IkappaB-α mRNA. The IkappaB's degradation proteins were determined by Western-blot assay. Results We demonstrated the persistent activation of NF-kappaB during early stages of hepatocarcinogenesis, which reached maximal level 30 min after partial hepatectomy. The DNA binding and transcriptional activity of NF-kappaB, were sustained during early steps of hepatocarcinogenesis in comparison to only partial hepatectomy, which displayed a transitory NF-kappaB activation. In early stages of hepatocarconogenesis, the IkappaB-α degradation turned out to be acute and transitory, but the low levels of IkappaB-β persisted even 15 days after partial hepatectomy. Interestingly, IkappaB-β degradation is not induced after sole partial hepatectomy. Conclusion We propose that during liver regeneration, the transitory stimulation of the transcription factor response, assures blockade of NF-kappaB until recovery of the total mass of the liver and the persistent NF-kappaB activation in early hepatocarcinogenesis may be due to IkappaB-β and IkappaB-α degradation, mainly IkappaB-β degradation, which contributes to gene transcription related to proliferation required for neoplasic progression.

  9. Quantum mechanical model for the anticarcinogenic effect of extremely-low-frequency electromagnetic fields on early chemical hepatocarcinogenesis

    Science.gov (United States)

    Godina-Nava, Juan José; Torres-Vega, Gabino; López-Riquelme, Germán Octavio; López-Sandoval, Eduardo; Samana, Arturo Rodolfo; García Velasco, Fermín; Hernández-Aguilar, Claudia; Domínguez-Pacheco, Arturo

    2017-02-01

    Using the conventional Haberkorn approach, it is evaluated the recombination of the radical pair (RP) singlet spin state to study theoretically the cytoprotective effect of an extremely-low-frequency electromagnetic field (ELF-EMF) on early stages of hepatic cancer chemically induced in rats. The proposal is that ELF-EMF modulates the interconversion rate of singlet and triplet spin states of the RP populations modifying the products from the metabolization of carcinogens. Previously, we found that the daily treatment with ELF-EMF 120 Hz inhibited the number and area of preneoplastic lesions in chemical carcinogenesis. The singlet spin population is evaluated diagonalizing the spin density matrix through the Lanczos method in a radical pair mechanism (RPM). Using four values of the interchange energy, we have studied the variations over the singlet population. The low magnetic field effect as a test of the influence over the enzymatic chemical reaction is evaluated calculating the quantum yield. Through a bootstrap technique the range is found for the singlet decay rate for the process. Applying the quantum measurements concept, we addressed the impact toward hepatic cells. The result contributes to improving our understanding of the chemical carcinogenesis process affected by charged particles that damage the DNA.

  10. The Epidermal Growth Factor Receptor (EGFR) Inhibitor Gefitinib Reduces but Does Not Prevent Tumorigenesis in Chemical and Hormonal Induced Hepatocarcinogenesis Rat Models

    OpenAIRE

    Silvia Ribback; Verena Sailer; Enrico Böhning; Julia Günther; Jaqueline Merz; Frauke Steinmüller; Kirsten Utpatel; Antonio Cigliano; Kristin Peters; Pilo, Maria G.; Matthias Evert; Calvisi, Diego F.; Frank Dombrowski

    2016-01-01

    Activation of the epidermal growth factor receptor (EGFR) signaling pathway promotes the development of hepatocellular adenoma (HCA) and carcinoma (HCC). The selective EGFR inhibitor Gefitinib was found to prevent hepatocarcinogenesis in rat cirrhotic livers. Thus, Gefitinib might reduce progression of pre-neoplastic liver lesions to HCC. In short- and long-term experiments, administration of N-Nitrosomorpholine (NNM) or intrahepatic transplantation of pancreatic islets in diabetic (PTx), thy...

  11. Effect of boschniakia rossica on expression of GST-P, p53 and p21ras proteinsin early-stage chemical hepatocarcinogenesis and its anti-inflammatoryactivities in rats

    Institute of Scientific and Technical Information of China (English)

    Zong Zhu Yin; Hai Ling Jin; Xue Zhe Yin; Tian Zhu Li; Ji Shu Quan; Zeng Nan Jin

    2000-01-01

    AIM To investigate the effect of boschniakia rossica (BR) extract on expression of GST-P, p53 and p21fasproteins in early-stage chemical hepatocarcinogenesis in rats and its anti-inflammatory actions.METHODS The expression of tumor marker, placental form glutathione S-transferase (GST-P), p53 and p21ras proteins were investigated by immunohistochemical techniques and ABC method. Anti-inflammatoryactivities of BR were observed by xylene and croton oil-induced mouse ear edema, carrageenin, histamineand hot scald-induced rat pow edema, adjuvant-induced rat arthritis and cotton pellet-induced mousegranuloma formation methods.RESULTS The 500 mg/kg of BR-H2O extract fractionated from BR-Methanol extract had inhibitory effecton the formation of DEN-induced GST-P-positive foci in rat liver and the expression of mutant p53 and p21fasprotein was lower than that of hepatic preneoplastic lesions. Both CH2Cl2 and H2O extract from BR haveinhibitory effect in xylene and croton oil-induced mouse ear edema. BR-H2O extract exhibited inhibitoryeffect in carrageenin, histamine and hot scald-induced hind paw edema and adjuvant-induced arthritis in ratsand cotton pellet-induced granuloma formation in mice.CONCLUSION BR extract exhibited inhibitory effect on formation of preneoplastic hepatic foci in earlystage of rat chemical hepatocarcinogenesis. Both CH2Cl2 and H2O extract from BR exerted anti-inflammatory effect in rats and mice.

  12. Genetic alterations and epigenetic changes in hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Luz Stella Hoyos Giraldo

    2007-02-01

    -family: QuorumITCbyBT-Book">Dietary factors have a role in the modification of epigenetic changes. Altered expression of DNMT mRNA and DNA hypermethylation of TSGs, has been observed in HCC. The mechanism of the interaction between chemical carcinogens and changes of methylation is still unclear and need much more research. Risk factors for hepatocarcinogenesis and their genetic and epigenetic reactions remains poorly understood.

  13. Effect of Boschniakia rossica on expression of GST-P, p53 and p21(ras)proteins in early stage of chemical hepatocarcinogenesis and its anti-inflammatory activities in rats.

    Science.gov (United States)

    Yin, Zong-Zhu; Jin, Hai-Ling; Yin, Xue-Zhe; Li, Tian-Zhu; Quan, Ji-Shu; Jin, Zeng-Nan

    2000-12-01

    AIM:To investigate the effect of Boschniakia rossica (BR) extract on expression of GST-P, p53 and p21(ras) proteins in early stage of chemical hepatocarcinogenesis in rats and its anti-inflammatory activities.METHODS:The expression of tumor marker-placental form glutathione S-transferase (GST-P), p53 and p21(ras) proteins were investigated by immunohisto-chemical techniques and ABC method. Anti-inflammatory activities of BR were studied by xylene and croton oil-induced mouse ear edema, carrageenin, histamine and hot scald-induced rat pow edema, adjuvant-induced rat arthritis and cotton pellet induced mouse granuloma formation methods.RESULTS:The 500mg/kg of BR-H2O extract frac-tionated from BR-Methanol extract had inhibitory effect on the formation of DEN-induced GST-P-positive foci in rat liver (GST-P staining was 78% positive in DEN+AAF group vs 20% positive in DEN+AAF+BR group, Panti-inflamatory effect in xylene and crotonoil induced mouse ear edema (inhibitory rates were 26%-29% and 35%-59%, respectively). BR H(2)O extract exhibited inhibitory effect in carrageenin, histamine and hot scald-induced hind paw edema and adjuvant-induced arthritis in rats and cotton pellet-induced granuloma formation in mice.CONCLUSION:BR extract exhibited inhibitory effect on formation of preneoplastic hepatic foci in early stage of rat chemical hepato-carcinogenesis.Both CH(2)Cl(2) and H(2)O extracts from BR exerted anti-inflammatory effect in rats and mice.

  14. Integrated luminescent chemical microsensors based on GaN LEDs for security applications using smartphones

    Science.gov (United States)

    Orellana, Guillermo; Muñoz, Elias; Gil-Herrera, Luz K.; Muñoz, Pablo; Lopez-Gejo, Juan; Palacio, Carlos

    2012-09-01

    Development of PCB-integrateable microsensors for monitoring chemical species is a goal in areas such as lab-on-a-chip analytical devices, diagnostics medicine and electronics for hand-held instruments where the device size is a major issue. Cellular phones have pervaded the world inhabitants and their usefulness has dramatically increased with the introduction of smartphones due to a combination of amazing processing power in a confined space, geolocalization and manifold telecommunication features. Therefore, a number of physical and chemical sensors that add value to the terminal for health monitoring, personal safety (at home, at work) and, eventually, national security have started to be developed, capitalizing also on the huge number of circulating cell phones. The chemical sensor-enabled "super" smartphone provides a unique (bio)sensing platform for monitoring airborne or waterborne hazardous chemicals or microorganisms for both single user and crowdsourcing security applications. Some of the latest ones are illustrated by a few examples. Moreover, we have recently achieved for the first time (covalent) functionalization of p- and n-GaN semiconductor surfaces with tuneable luminescent indicator dyes of the Ru-polypyridyl family, as a key step in the development of innovative microsensors for smartphone applications. Chemical "sensoring" of GaN-based blue LED chips with those indicators has also been achieved by plasma treatment of their surface, and the micrometer-sized devices have been tested to monitor O2 in the gas phase to show their full functionality. Novel strategies to enhance the sensor sensitivity such as changing the length and nature of the siloxane buffer layer are discussed in this paper.

  15. Possible quantum mechanical mechanism for hepatocarcinogenesis

    Science.gov (United States)

    Torres-Vega, G.; Godina-Nava, J. J.; Morales-Peñaloza, A.; Jiménez-García, M. N.

    2012-10-01

    We describe a method to study the effects of an extremely low frequency electromagnetic field (ELF-EMF) on the development of preneoplastic lesions in experimental hepatocarcinogenesis. The method uses the dual Lanczos transformation theory to diagonalize the Liouville superoperator that describe the evolution of a radical pair. We illustrate this procedure with a simple two level system.

  16. Super low power consumption middle infrared LED-PD optopairs for chemical sensing

    Science.gov (United States)

    Stoyanov, Nikolay D.; Salikhov, Khafiz M.; Kalinina, Karina V.; Kizhaev, Sergey S.; Chernyaev, Anton V.

    2014-03-01

    The new photodiodes with cut-off wavelengths at 3640 nm, 4600 nm and 5150 nm have been recently developed in a high-tech company LED Microsensor NT (St.Petersburg, Russia) in cooperation with Aalto University (Espoo, Finland). Photodiode (PD) heterostructures InAsSb/InAsSbP were grown by MOVPE on InAs substrates. For the PDs with a cutoff wavelength at 3640 nm at room temperature the responsivity at 3300 nm reached 1.46 A/W and, detectivity was 1.56*1010 cm.Hz1/2/W. For the PDs with a cut-off 4600 nm the same parameters were: 1.91 A/W and 6.7*109 cm.Hz1/2/W respectively (lambda=4100 nm). For the third type of PDs with a cut-off at 5150 nm responsivity was 0.29 A/W, detectivity was 4.2*108 cm.Hz1/2/W (lambda=5000 nm). Creation of photodiodes for the spectral range 2500-5200 nm with acceptable efficiency in photovoltaic operation mode (with no reverse bias) and using them in a pair with spectrally matched LEDs driven by very short current pulses allows developing optical cells with very low power consumption (less than 1 mW). Small size of the LED and PD dies (0.4-0.8 mm) and low heating makes it possible to design very thin optical cells (less than 2 mm) for measuring CH4, CO2, CO, H2O and other substances [1]. Mounting of a few LED dies that emit at different wavelengths in such a small cell allows measuring different chemical substances simultaneously. Direct coating of optical filters on the LED or PD surface during post-growth process allows improving selectivity and sensitivity of the sensor. Super low power consumption of the diode-based optical cells makes them promising candidates for the wireless mesh sensor networks for various gas monitoring purposes as well as for HVAC systems. Combination of the low power consumption and thin size of the cells opens possibility to embed them in mobile devices.

  17. Role of liver stem cells in hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Lei-Bo; Xu; Chao; Liu

    2014-01-01

    Liver cancer is an aggressive disease with a high mortality rate. Management of liver cancer is strongly dependent on the tumor stage and underlying liver disease. Unfortunately, most cases are discovered when the cancer is already advanced, missing the opportunity for surgical resection. Thus, an improved understanding of the mechanisms responsible for liver cancer initiation and progression will facilitate the detection of more reliable tumor markers and the development of new small molecules for targeted therapy of liver cancer. Recently, there is increasing evidence for the "cancer stem cell hypothesis", which postulates that liver cancer originates from the malignant transformation of liver stem/progenitor cells(liver cancer stem cells). This cancer stem cell model has important significance for understanding the basic biology of liver cancer and has profound importance for the development of new strategies for cancer prevention and treatment. In this review, we highlight recent advances in the role of liver stem cells in hepatocarcinogenesis. Our review of the literature shows that identification of the cellular origin and the signaling pathways involved is challenging issues in liver cancer with pivotal implications in therapeutic perspectives. Although the dedifferentiation of mature hepatocytes/cholangiocytes in hepatocarcinogenesis cannot be excluded, neoplastic transformation of a stem cell subpopulation more easily explains hepatocarcinogenesis. Elimination of liver cancer stem cells in liver cancer could result in the degeneration of downstream cells, which makes them potential targets for liver cancer therapies. Therefore, liver stem cells could represent a new target for therapeutic approaches to liver cancer in the near future.

  18. Si-nanocrystal-based LEDs fabricated by ion implantation and plasma-enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Peralvarez, M; Carreras, Josep; Navarro-Urrios, D; Lebour, Y; Garrido, B [MIND, IN2UB, Department of Electronics, University of Barcelona, C/Marti i Franques 1, PL2, E-08028 Barcelona (Spain); Barreto, J; DomInguez, C [IMB-CNM, CSIC, Bellaterra, E-08193 Barcelona (Spain); Morales, A, E-mail: mperalvarez@el.ub.e [INAOE, Electronics Department, Apartado 51, Puebla 72000 (Mexico)

    2009-10-07

    An in-depth study of the physical and electrical properties of Si-nanocrystal-based MOSLEDs is presented. The active layers were fabricated with different concentrations of Si by both ion implantation and plasma-enhanced chemical vapour deposition. Devices fabricated by ion implantation exhibit a combination of direct current and field-effect luminescence under a bipolar pulsed excitation. The onset of the emission decreases with the Si excess from 6 to 3 V. The direct current emission is attributed to impact ionization and is associated with the reasonably high current levels observed in current-voltage measurements. This behaviour is in good agreement with transmission electron microscopy images that revealed a continuous and uniform Si nanocrystal distribution. The emission power efficiency is relatively low, {approx}10{sup -3}%, and the emission intensity exhibits fast degradation rates, as revealed from accelerated ageing experiments. Devices fabricated by chemical deposition only exhibit field-effect luminescence, whose onset decreases with the Si excess from 20 to 6 V. The absence of the continuous emission is explained by the observation of a 5 nm region free of nanocrystals, which strongly reduces the direct current through the gate. The main benefit of having this nanocrystal-free region is that tunnelling current flow assisted by nanocrystals is blocked by the SiO{sub 2} stack so that power consumption is strongly reduced, which in return increases the device power efficiency up to 0.1%. In addition, the accelerated ageing studies reveal a 50% degradation rate reduction as compared to implanted structures.

  19. Effect of coupled UV-A and UV-C LEDs on both microbiological and chemical pollution of urban wastewaters

    Energy Technology Data Exchange (ETDEWEB)

    Chevremont, A.-C., E-mail: anne-celine.chevremont@imbe.fr [Aix-Marseille Universite - CNRS, FR ECCOREV, Laboratoire Chimie de l' Environnement (FRE3416), Equipe ' Developpements Metrologiques et Chimie des Milieux' , 3 place Victor Hugo, case 29, 13331 Marseille Cedex 3 (France); Aix-Marseille Universite - CNRS, FR ECCOREV, Institut Mediterraneen de Biodiversite et d' Ecologie marine et continentale (UMR7263), Equipe ' Vulnerabilite des Systemes Microbiens' , Avenue Escadrille Normandie-Niemen, Boite 452, 13397 Marseille Cedex 20 (France); Farnet, A.-M. [Aix-Marseille Universite - CNRS, FR ECCOREV, Institut Mediterraneen de Biodiversite et d' Ecologie marine et continentale (UMR7263), Equipe ' Vulnerabilite des Systemes Microbiens' , Avenue Escadrille Normandie-Niemen, Boite 452, 13397 Marseille Cedex 20 (France); Coulomb, B.; Boudenne, J.-L. [Aix-Marseille Universite - CNRS, FR ECCOREV, Laboratoire Chimie de l' Environnement (FRE3416), Equipe ' Developpements Metrologiques et Chimie des Milieux' , 3 place Victor Hugo, case 29, 13331 Marseille Cedex 3 (France)

    2012-06-01

    Wastewater reuse for irrigation is an interesting alternative for many Mediterranean countries suffering from water shortages. The development of new technologies for water recycling is a priority for these countries. In this study we test the efficiency of UV-LEDs (Ultraviolet-Light-Emitting Diodes) emitting UV-A or UV-C radiations, used alone or coupled, on bacterial and chemical indicators. We monitored the survival of fecal bioindicators found in urban wastewaters and the oxidation of creatinine and phenol which represent either conventional organic matter or the aromatic part of pollution respectively. It appears that coupling UV-A/UV-C i) achieves microbial reduction in wastewater more efficiently than when a UV-LED is used alone, and ii) oxidizes up to 37% of creatinine and phenol, a result comparable to that commonly obtained with photoreactants such as TiO{sub 2}. - Highlights: Black-Right-Pointing-Pointer We test UV-LEDs as an urban wastewater tertiary treatment. Black-Right-Pointing-Pointer UV-A and UV-C are coupled, combining germicidal and oxidative properties of UV. Black-Right-Pointing-Pointer Coupled wavelengths have the most efficient bactericidal effect. Black-Right-Pointing-Pointer Coupling UV-A and UV-C leads to photooxidation of creatinine and phenol.

  20. Oncogene Mdm2 takes part in hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective:To investigate the role of Mdm2 expression in hepatocellular carcinoma.Methods: Streptavidin-peroxidase conjugation method (SP)was used to observe the expression of Mdm2 and p53 proteins in 61 cases of hepatocellular carcinoma(HCC)and 59 cases of corresponding paracancerous tissues,among which p53 mutations in exons 5~8 were detected in 21 cases by PCR-SSCP.Results:Positive nuclear P53 and Mdm2 immunostains were demonstrated in 57.38% and 26.23% of HCC,1.69% and 3.39% of corresponding paracancerous tissues respectively.The expression of p53 and Mdm2 proteins in hepatocellular carcinoma was significantly higher than that in paracancerous tissues(P<0.01).The expression of P53 and Mdm2 was not significantly correlated.42.86% of hepatocellualr carcinomas showed mutations in exon 7 of p53 gene,and no mutation was found in exons 5,6,8 and paracancerous tissues. 66.67% of mutational cases had P53 overexpression and 11.11%(1/9)showed overexpression of both P53 and Mdm2,Mdm2 overexpression also appeared in 25% of cases without mutations.Conclusions:Mdm2-induced p53 inactivation and p53 gene mutation play an important role in carcinogenesis of hepatocellular carcinoma.Tumorigenic property of Mdm2 itself,together with p53 mutation,may take part in hepatocarcinogenesis.

  1. Inexpensive, pocket-sized LED-based fluorometer for undergraduate teaching laboratories and in-the-field chemical detection

    Science.gov (United States)

    Tiber, Gage; Basu, Partha; Corcovilos, Theodore A.

    2015-05-01

    Fluorometry is a standard experimental technique for the detection of chemical compounds in solution. Excitation light is absorbed by a sample and then longer-wavelength light is emitted. Typical laboratory fluorometers are large and expensive, making them poorly suited for field work and teaching laboratories. We present a simple battery-powered fluorometer built with off-the-shelf components and a 3D-printed body. The light sources are user-replaceable light emitting diodes (LEDs). Two independent light sources of different wavelengths allow ratiometric measurements of the sample. The detectors are photodiodes with interchangeable dielectric Fabry-Perot stack spectral filters. The light gathering optics are designed using non-imaging optics principles to maximize the amount of detected fluorescence light. We present the design of the device and demonstrate the sensitivity using a molecular detector of Pb2+ ions in solution. The absorption and emission wavelengths of the detector molecule change from 415 nm and 465 nm, resp., in the absence of Pb2+ to 389 nm and 423 nm, resp., in the presence of Pb2+. The estimated sensitivity of the fluorometer with this molecular detector is a few p.p.b.

  2. Nanorods on surface of GaN-based thin-film LEDs deposited by post-annealing after photo-assisted chemical etching

    Science.gov (United States)

    Chen, Lung-Chien; Lin, Wun-Wei; Liu, Te-Yu

    2017-01-01

    This study investigates the optoelectronic characteristics of gallium nitride (GaN)-based thin-film light-emitting diodes (TF-LEDs) that are formed by a two-step transfer process that involves wet etching and post-annealing. In the two-step transfer process, GaN LEDs were stripped from sapphire substrates by the laser lift-off (LLO) method using a KrF laser and then transferred onto ceramic substrates. Ga-K nanorods were formed on the surface of the GaN-based TF-LEDs following photo-assisted chemical etching and photo-enhanced post-annealing at 100 °C for 1 min. As a result, the light output power of GaN-based TF-LEDs with wet etching and post-annealing was over 72% more than that of LEDs that did not undergo these treatments.

  3. Folic acid supplementation during early hepatocarcinogenesis: cellular and molecular effects.

    Science.gov (United States)

    Chagas, Carlos Eduardo Andrade; Bassoli, Bruna Kempfer; de Souza, Camila Alexandre Soares; Deminice, Rafael; Jordão Júnior, Alceu Afonso; Paiva, Sérgio Alberto Rupp; Dagli, Maria Lúcia Zaidan; Ong, Thomas Prates; Moreno, Fernando Salvador

    2011-11-01

    Folic acid (FA) supplementation during carcinogenesis is controversial. Considering the impact of liver cancer as a public health problem and mandatory FA fortification in several countries, the role of FA supplementation in hepatocarcinogenesis should be elucidated. We evaluated FA supplementation during early hepatocarcinogenesis. Rats received daily 0.08 mg (FA8 group) or 0.16 mg (FA16 group) of FA/100 g body weight or water (CO group, controls). After a 2-week treatment, animals were subjected to the "resistant hepatocyte" model of hepatocarcinogenesis (initiation with diethylnitrosamine, selection/promotion with 2-acetylaminofluorene and partial hepatectomy) and euthanized after 8 weeks of treatment. Compared to the CO group, the FA16 group presented: reduced (p PNL); reduced (p PNL; decreased (p PNL. Regarding all these parameters, no differences (p > 0.05) were observed between CO and FA8 groups. FA-treated groups presented increased hepatic levels of S-adenosylmethionine but only FA16 group presented increased S-adenosylmethionine/S-adenosylhomocysteine ratio. No differences (p > 0.05) were observed between experimental groups regarding apoptosis in persistent and remodeling GST-P positive PNL, and global DNA methylation pattern in microdissected PNL. Altogether, the FA16 group, but not the FA8 group, presented chemopreventive activity. Reversion of PNL phenotype and inhibition of DNA damage and of c-myc expression represent relevant FA cellular and molecular effects.

  4. Review: Exploring anticarcinogenic agents in a rat hepatocarcinogenesis model--focus on selenium and statins.

    Science.gov (United States)

    Björkhem-Bergman, Linda; Ekström, Lena; Eriksson, Lennart C

    2012-01-01

    In this review, we describe a rat model for chemically induced hepatocarcinogenesis that can be used for studying the anticarcinogenic effects of different agents. In this model the process of carcinogenesis can be followed through the different stages of initiation, promotion and progression. Mechanistic studies of anticarcinogenic agents can be carried out and two examples are given by studies on selenium and statins as anticarcinogenic agents. These compounds suppress cancer via different mechanisms. In the case of selenium the induction of glutathione peroxidase 4 and inhibition of lipid peroxidation might be a part of the anticarcinogenic effect. In the case of statins, the inhibition of ubiquinone synthesis, as well as of the selenium-containing enzyme thioredoxin reductase 1 (TrxR1) might explain their anticarcinogenic properties. Interestingly, also in the case of selenium the inhibited carcinogenesis was associated with reduced TrxR activity, indicating an important role for this enzyme in carcinogenesis.

  5. Modulation of radical pairs dynamics immersed in an ELF-EMF: The effect on hepatocarcinogenesis

    Science.gov (United States)

    López-Riquelme, G. O.; López-Sandoval, E.; Vera-Aguilar, E.; Godina-Nava, J. J.

    2015-01-01

    The most suitable mechanism of action of electromagnetic fields (EMF) on biological systems is the effect on the radical pair (RP) recombination through the Zeeman effect and hyperfine interaction, which changes the rate of reactions or the product distribution. Enzyme reactions with RP intermediates can be altered by EMF, like those catalyzed by cytochrome P450 enzymes (CYP450), a heme-thiolate family protein that detoxifies xenobiotics and involved in chemical carcinogenesis. CYP450 activate chemical carcinogens producing an enormous amount of free radicals, which damage the DNA resulting in the malignant transformation of cells. During the activation, CYP450 produce spin-correlated RP intermediates that can either go to recombination or to continue the catalytic process. As CYP450 are electron carrier proteins, it is possible that RP intermediates may be affected by EMF. It was previously found that periodic treatment with extremely low frequency electromagnetic fields (ELF-EMF) inhibits more than 50% the number and area of preneoplastic lesions in rats with chemically induced hepatocarcinogenesis through reduction of cell proliferation. In this work, we developed a quantum mechanical model based on RP mechanism in order to explain the experimental effects of ELF-EMF on the free radicals produced in the early stages of chemical carcinogenesis.

  6. Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

    Energy Technology Data Exchange (ETDEWEB)

    He Ying, E-mail: yinghe@staff.shu.edu.c [Shanghai University, Department of Polymer Materials, School of Materials Science and Engineering (China); Wang Junan [Shanghai University, Institute of Materials, School of Materials Science and Engineering (China); Pei Changlong; Song Jizhong; Zhu Di; Chen Jie [Shanghai University, Department of Polymer Materials, School of Materials Science and Engineering (China)

    2010-10-15

    A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

  7. Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

    Science.gov (United States)

    He, Ying; Wang, Jun-An; Pei, Chang-Long; Song, Ji-Zhong; Zhu, Di; Chen, Jie

    2010-10-01

    A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

  8. Enhancing effects of dimethylnitrosamine on aflatoxin B hepatocarcinogenesis in rats.

    Science.gov (United States)

    Angsubhakorn, S; Bhamarapravati, N; Romruen, K; Sahaphong, S

    1981-11-15

    In a study of possible enhancing effects of dimethylnitrosamine (DMN) on aflatoxin B1 (AFB1) hepatocarcinogenesis, male Buffalo strain rats were fed diets containing 1 ppm AFB1, 25 ppm DMN, and a combination of 1 ppm AFB1 and 25 ppm DMN (AFB1 + DMN). The diets were replaced by chow pellets after 6 months, and animals were killed 3, 6, 9 and 12 months after the onset of the experiment. In the untreated control group animals were free of hepatocellular carcinoma but the treated groups fed AFB1, DMN and AFB1 plus DMN developed hepatic lesions ranging from multiple cysts, altered cell foci and neoplastic nodules to hepatocellular carcinomas. Hepatocellular carcinomas developed in 79%, 45% and 5% of rats fed AFB1 plus DMN, AFB1 and DMN respectively at the end of the experiment. Multiple cysts were also found in all periods in animals fed AFB1 plus DMN, whereas rats fed AFB1 and DMN separately developed a few multiple cysts by the end of the experiment. These findings suggest that DMN potentiates the hepatocarcinogenesis induced by AFB1 in rats.

  9. Chlorella vulgaris triggers apoptosis in hepatocarcinogenesis-induced rats

    Institute of Scientific and Technical Information of China (English)

    Emey Suhana MOHD AZAMAI; Suhaniza SULAIMAN; Shafina Hanim MOHD HABIB; Mee Lee LOOI; Srijit DAS; Nor Aini ABDUL HAMID; Wan Zurinah WANG NGAH; Yasmin Anum MOHD YUSOF

    2009-01-01

    Chlorella vulgaris (CV) has been reported to have antioxidant and anticancer properties. We evaluated the effect of CV on apoptotic regulator protein expression in liver cancer-induced rats. Male Wistar rats (200-250 g) were divided into eight groups: control group (normal diet), CDE group (choline deficient diet supplemented with ethionine in drinking water to induce hepatocarcinogenesis), CV groups with three different doses of CV (50, 150, and 300 mg/kg body weight), and CDE groups treated with different doses of CV (50, 150, and 300 mg/kg body weight). Rats were sacrificed at various weeks and liver tissues were embedded in paraffin blocks for immunohistochemistry studies. CV, at increasing doses, decreased the expression of anti-apoptotic protein, Bcl-2, but increased the expression of pro-apoptotic protein, caspase 8, in CDE rats, which was correlated with decreased hepatoctyes proliferation and increased apoptosis as determined by bromodeoxy-uridine (BrdU) labeling and terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) assay, respectively. Our study shows that CV has definite chemopreventive effect by inducing apoptosis via decreasing the expression of Bcl-2 and increasing the expression of caspase 8 in hepatocarcinogenesis-induced rats.

  10. Inflammation-and stress-related signaling pathways in hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Hayato Nakagawa; Shin Maeda

    2012-01-01

    It has been established that cancer can be promoted and exacerbated by inflammation.Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide,and its long-term prognosis remains poor.Although HCC is a complex and heterogeneous tumor with several genomic mutations,it usually develops in the context of chronic liver damage and inflammation,suggesting that understanding the mechanism(s) of inflammation-mediated hepatocarcinogenesis is essential for the treatment and prevention of HCC.Chronic liver damage induces a persistent cycle of necroinflammation and hepatocyte regeneration,resulting in genetic mutations in hepatocytes and expansion of initiated cells,eventually leading to HCC development.Recently,several inflammation-and stress-related signaling pathways have been identified as key players in these processes,which include the nuclear factorκB,signal transducer and activator of transcription,and stress-activated mitogen-activated protein kinase pathways.Although these pathways may suggest potential therapeutic targets,they have a wide range of functions and complex crosstalk occurs among them.This review focuses on recent advances in our understanding of the roles of these signaling pathways in hepatocarcinogenesis.

  11. LED lamp

    Science.gov (United States)

    Galvez, Miguel; Grossman, Kenneth; Betts, David

    2013-11-12

    There is herein described a lamp for providing white light comprising a plurality of light sources positioned on a substrate. Each of said light sources comprises a blue light emitting diode (LED) and a dome that substantially covers said LED. A first portion of said blue light from said LEDs is transmitted through said domes and a second portion of said blue light is converted into a red light by a first phosphor contained in said domes. A cover is disposed over all of said light sources that transmits at least a portion of said red and blue light emitted by said light sources. The cover contains a second phosphor that emits a yellow light in response to said blue light. The red, blue and yellow light combining to form the white light and the white light having a color rendering index (CRI) of at least about 80.

  12. Photocatalytic decomposition of selected estrogens and their estrogenic activity by UV-LED irradiated TiO2 immobilized on porous titanium sheets via thermal-chemical oxidation.

    Science.gov (United States)

    Arlos, Maricor J; Liang, Robert; Hatat-Fraile, Melisa M; Bragg, Leslie M; Zhou, Norman Y; Servos, Mark R; Andrews, Susan A

    2016-11-15

    The removal of endocrine disrupting compounds (EDCs) remains a big challenge in water treatment. Risks associated with these compounds are not clearly defined and it is important that the water industry has additional options to increase the resiliency of water treatment systems. Titanium dioxide (TiO2) has potential applications for the removal of EDCs from water. TiO2 has been immobilized on supports using a variety of synthesis methods to increase its feasibility for water treatment. In this study, we immobilized TiO2 through the thermal-chemical oxidation of porous titania sheets. The efficiency of the material to degrade target EDCs under UV-LED irradiation was examined under a wide range of pH conditions. A yeast-estrogen screen assay was used to complement chemical analysis in assessing removal efficiency. All compounds but 17β-estradiol were degraded and followed a pseudo first-order kinetics at all pH conditions tested, with pH 4 and pH 11 showing the most and the least efficient treatments respectively. In addition, the total estrogenic activity was substantially reduced even with the inefficient degradation of 17β-estradiol. Additional studies will be required to optimize different treatment conditions, UV-LED configurations, and membrane fouling mitigation measures to make this technology a more viable option for water treatment.

  13. Immunobiology of hepatocarcinogenesis: Ways to go or almost there?

    Institute of Scientific and Technical Information of China (English)

    Pavan Patel; Steven E Schutzer; Nikolaos Pyrsopoulos

    2016-01-01

    Hepatocellular carcinoma is on the rise and occurs in the setting of chronic liver disease and cirrhosis.Though treatment modalities are available,mortality from this cancer remains high.Medical therapy with the utilization of biologic compounds such as the Food and Drug Administration approved sorafenib might be the only option that can increase survival.Immunotherapy,with modern pharmacologic developments,is a new frontier in cancer therapy and therefore the immunobiology of hepatocarcinogenesis is under investigation.This review will discuss current concepts of immunobiology in hepatocarcinogenesis along with current treatment modalities employing immunotherapy.The tumor microenvironment along with a variety of immune cells coexists and interplays to lead to tumorigenesis.Tumor infiltrating lymphocytes including CD8+ T cells,CD4+ T cells along with regulatory T cells,tumor associated macrophages,tumor associated neutrophils,myeloid derived suppressor cells,and natural killer cells interact to actively provide anti-tumor or pro-tumor effects.Furthermore,oncogenic pathways such as Raf/mitogenactivated protein kinase/extracellular-signal-regulated kinase pathway,phosphatidyl-3-kinase/AKT/mammalian target or rapamycin,Wnt/β-catenin,nuclear factor-κB and signal transducers and activators of transcription 3 may lead to activation and proliferation of tumor cells and are also considered cornerstones in tumorigenesis.Immunotherapy directed at this complex milieu of cells has been showned to be successful in cancer treatment.The use of vaccines,adoptive cell therapy and immune checkpoint inhibitor modulation are current options for therapy.Further translational research will shed light to concepts such as anti-tumor immunity which can add another alternative in the therapeutic armamentarium.

  14. Changes of integrin expression in rat hepatocarcinogenesis induced by 3′-Me-DAB

    Institute of Scientific and Technical Information of China (English)

    Sheng Tao Yuan; Xi Qi Hu; Jian Ping Lu; Wei Rong Zhai; Yue E Zhang; Hayashi KeiKi

    2000-01-01

    AIM To investigate the expression of integrins in rats liver during 3 '-Me-DAB induced hepatocarcinogenesis and to find out the relationship between integrins and liver cancer metastasis. METHODS The expressions of integrins α1, α2,α3 and α5 and epidermal keratin (EK) were observed by immunohistochemical PAP method.RESULTS In the normal liver tissues,hepatocytes express integrins α1 and α5 and in the bile duct epithlium, EK. In liver cirrhosis,hepatocytes highly express integrins α1, α2, α3 and α5 and in hyperplsstic bile duct epithelium,integrins α1, α5 and EK. Expression of integrins α1, α2, α3 and α5 were obviously decreased in the preneoplsstic nodules and primary carcinoma but expressions of integrins α1 and α5 in metastasis in the lung and diaphragme were higher than those in primary carcinoma.CONCLUSION Integrins α1 and α5 may play a major role in chemically induced hepatocarcinogenssis and metastasis in rats.

  15. Recycling of metal-organic chemical vapor deposition waste of GaN based power device and LED industry by acidic leaching: Process optimization and kinetics study

    Science.gov (United States)

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon; Park, Jeung-Jin

    2015-05-01

    Recovery of metal values from GaN, a metal-organic chemical vapor deposition (MOCVD) waste of GaN based power device and LED industry is investigated by acidic leaching. Leaching kinetics of gallium rich MOCVD waste is studied and the process is optimized. The gallium rich waste MOCVD dust is characterized by XRD and ICP-AES analysis followed by aqua regia digestion. Different mineral acids are used to find out the best lixiviant for selective leaching of the gallium and indium. Concentrated HCl is relatively better lixiviant having reasonably faster kinetic and better leaching efficiency. Various leaching process parameters like effect of acidity, pulp density, temperature and concentration of catalyst on the leaching efficiency of gallium and indium are investigated. Reasonably, 4 M HCl, a pulp density of 50 g/L, 100 °C and stirring rate of 400 rpm are the effective optimum condition for quantitative leaching of gallium and indium.

  16. Expression and hypermethylation of p27kip1 in hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Pu-Ping Lei; Zong-Ji Zhang; Li-Juan Shen; Jin-Yun Li; Qiong Zou; Hua-Xian Zhang

    2005-01-01

    AIM: To study the expressions of p27kip1 protein and p27mRNA, the hypermethylation of p27kip1 and the relation between them in various stages of hepatocarcinogenesis.METHODS: p27 protein and p27mRNA were detected by immunohistochemical staining and in situ hybridization respectively in 68 cases of normal liver, liver cirrhosis,pericancerous cirrhosis and hepatocellular carcinoma (HCC). The hypermethylation of p27kip1 was detected by methylation-specific PCR (MSP) in 44 cases of normal liver, liver cirrhosis, and HCC.RESULTS: The positive rate of p27 protein was 66.7% (4/6) in normal liver, 60.0% (6/10) in liver cirrhosis, 50.0% (12/24) in pericancerous cirrhosis and 21.4% (6/28) in HCC. There were no statistical differences in normal liver,liver cirrhosis and pericancerous cirrhosis, but the positive rate of p27 protein significantly decreased in HCC compared to that in the other groups (P = 0.006,x2 = 7.664). The positive rate of p27kip1 mRNA was 83.3% (5/6) in normal liver, 70.0% (7/10) in liver cirrhosis, 75.0% (18/24) in pericancerous cirrhosis and 25.0% (7/28) in HCC. There were no statistical differences in normal liver, liver cirrhosis and pericancerous cirrhosis, but the positive rate of p27kip1 mRNA also significantly decreased in HCC compared to that in the other groups (P = 0.000,x2 = 16.600). In addition, there was a significant correlation between the expression of p27 protein and p27mRNA in the integrated group of normal liver and liver cirrhosis.However, no significant correlation was found between pericancerous cirrhosis and HCC. Using MSP, we found that 1 HCC in 44 cases (including 6 cases of normal liver,10 cases of liver cirrhosis and 28 cases of HCC) was methylated, whose p27 protein and p27mRNA were negative.CONCLUSION: The reduction or loss of p27 protein and p27mRNA are potentially involved in hepatocarcinogenesis.The hypermethylation of p27 might lead to the loss of p27mRNA transcription.

  17. Essential role of constitutive androstane receptor in Ginkgo biloba extract induced liver hypertrophy and hepatocarcinogenesis.

    Science.gov (United States)

    Maeda, Jun; Inoue, Kaoru; Ichimura, Ryohei; Takahashi, Miwa; Kodama, Yukio; Saito, Naoaki; Yoshida, Midori

    2015-09-01

    Ginkgo biloba extract (GBE) is commonly used as a herbal supplement. The National Toxicology Program (NTP) study of GBE reported clear evidence of hepatocarcinogenicity in mice. To clarify the mode of action (MOA) for hepatocarcinogenesis by GBE, we investigated the involvement of the constitutive androstane receptor (CAR) in hepatocarcinogenesis induced by GBE using CAR-knockout (CARKO) and wild type (WT) mice. We used the same lot of GBE that was used for the NTP study. In 1-week GBE dietary treatment, hepatocellular DNA replication was increased in WT mice but not in CARKO mice. In 4- or 13-week treatment, greater hepatic Cyp2b10 induction and hepatocellular hypertrophy were observed in WT mice, whereas these effects of GBE were much smaller in CARKO mice. In a two-stage hepatocarcinogenesis model initiated by diethylnitrosamine, 27-week treatment with GBE resulted in an increase of eosinophilic altered foci and adenomas in WT mice. By contrast, foci and adenomas were clearly less evident in CARKO mice. These results indicate that GBE-induced hepatocarcinogenesis is mainly CAR-mediated. Since CAR-mediated MOA for hepatocarcinogenesis in rodents is considered to be qualitatively implausible for humans, our findings would be helpful to evaluate the carcinogenic characterization of GBE to humans.

  18. [The role of platelet-derived growth factor and ras P21 in experimental hepatocarcinogenesis].

    Science.gov (United States)

    Zheng, J; Ruan, Y; Liu, B

    1996-04-01

    In order to explore whether platelet-derived growth factor (PDGF) is involved in hepatocarcinogenesis, expression of PDGF-beta chain and ras P21 were investigated using immunohistochemical method in hepatocarcinoma induced with diethylnitrosamine (DENA). Elevated PDGF-beta chain and P21 protein levels were found in hepatocytes in the early stages after DENA administration. Along with the progression of hepatocarcinogenesis, immunopositive cells were increased with the formation of various foci and nodules and the staining was usually stronger in the peripheral parts of nodules. In addition, PDGF-beta and P21 often expressed simultaneously in the smae lesions, where the cells were also positive for AFP expression. The results suggest that abnormal expression of PDGF might be an early specific event during hepatocarcinogenesis and might be involved in the malignant transformation of the hepatocytes by autocrine as well through ras P21 signal pathways.

  19. Role of Nuclear Constitutive Androstane Receptor in Regulation of Hepatocyte Proliferation and Hepatocarcinogenesis.

    Science.gov (United States)

    Kazantseva, Y A; Pustylnyak, Y A; Pustylnyak, V O

    2016-04-01

    Activation of the constitutive androstane receptor (CAR) in hepatocytes occurs as a body adaptation in response to a number of external influences, and its functional activity is primarily related to induction of enzymes detoxifying xenobiotics. However, special attention was recently given to CAR due to the fact that its key role becomes unveiled in various physiological and pathophysiological processes occurring in the liver: gluconeogenesis, metabolism of fatty acids and bilirubin, hormonal regulation, proliferation of hepatocytes, and hepatocarcinogenesis. Here we review the main pathways and mechanisms that elevate hepatocyte proliferative activity related to CAR and whose disturbance may be a pivotal factor in hepatocarcinogenesis.

  20. Protective Role of Lycopene Against Diethylnitrosamine Induced Experimental Hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Inas Z.A. Abdallah and Hala A.H. Khattab

    2004-09-01

    Full Text Available Lycopene was considered as a major carotenoid in the human diet for only the last few centuries. Recently lycopene has been found to possess chemoprotective effect against gastrointestinal tract, urinary bladder, prostate and breast cancers. In the present study, the protective effect of lycopene, the natural extract from tomato pomace against diethylnitrosamine (DEN-induced hepatocellular carcinoma (HCC formation in rats was investigated. Four groups of male albino rats at the age of 6 weeks were studied: 1 control (C, 2 DEN, i.p. injected 5 times with doses of 200 mg/kg b.w., one dose every two days. 3 Lycopene, orally given 0.12 mg/rat/day. 4 Lycopene + DEN, the treatment with lycopene started 7 days before DEN injection and continued till the end of the experimental period. Rats in group 2 and 4 were treated with Phenobarbital (PB at a dose of 500 ppm in the drinking water as a tumor promoter. PB treatment started with the first injection of DEN and continued till the end of the experimental period. The results indicated that DEN caused HCC nodules as evidenced by a remarkable significant increase in -L-fucosidase and metal oproteinases (MMPs enzyme activity in both serum and cytosol. Increased activity of these enzymes is a marker for both preneoplastic and carcinoma lesions. Administration of lycopene prior to DEN injection protected rats from DEN-induced HCC as evidenced by a significant descent in -L-fucosidase and MMPs enzymes activity in both serum and cytosol. The histological investigation of liver tissue confirmed these results. DEN group showed proliferated hyperplastic and anaplastic hepatocellular nodules surrounded with thin layer of fibroblastic cells, desmoplasia and inflammatory cells infiltrations, focal hepatic haemorrhages and necrosis. Meanwhile, lycopene + DEN group showed no histopathological changes. These results indicate that lycopene effectively inhibits DEN-induced hepatocarcinogenesis in rats.

  1. Molecular basis of hepatitis C virus -associated hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Isabelle Chemin

    2007-02-01

    for HCV (and HBV in human HCCs, also independently from axin/beta-catenin gene mutations. Induction of both endoplasmic reticulum stress and oxidative stress by HCV proteins might also contribute to HCV transformation. HCV proteins were shown to have an action on tumor suppressor genes, mitosis, apoptosis. Most of the putative transforming functions of the HCV proteins have been defined in artificial cellular systems, which may not be applicable to HCV infection in vivo, and still need to be established in relevant infection and disease models. Despite numerous lines of epidemiologic evidence connecting HCV infection and the development of HCC, it remains controversial whether HCV itself plays a direct role or an indirect role in the pathogenesis of HCC. Through the use of transgenic mice, it has become evident that the core protein of HCV has oncogenic potential. HCV is directly involved in hepatocarcinogenesis, albeit other factors such as inflammation and environmental factors might also play a role. The direct involvement of HCV in hepatocarcinogenesis would be achieved via at least 2 pathways. In one pathway, the core protein acts on the function of mitochondria, leading to the overproduction of oxidative stress, which yields genetic aberrations in cell growth-related genes. The other pathway involves the modulation of cellular gene expressions and intracellular signal transductions, such as mitogen-activated protein kinase pathway, which results in the activation of transcription factors and cell cycle machineries. The combination of these alterations would provoke the development of HCC in HCV infection. This may be a mechanism for HCC development in HCV infection that is distinct from those for other cancers. The presence of the HCV core protein, to which an oncogenic potential is ascribed, might allow some of the multiple steps to be bypassed in hepatocarcinogenesis. Therefore, unlike in other cancers, HCV infection might elicit HCC in the absence of a

  2. Protection against diethylnitrosoamine-induced hepatocarcinogenesis by an indigenous medicine comprised of Nigella sativa, Hemidesmus indicus and Smilax glabra: a preliminary study

    Directory of Open Access Journals (Sweden)

    Iddamaldeniya Samantha S

    2003-10-01

    Full Text Available Abstract Background A decoction comprised of Nigella sativa seeds, Hemidesmus indicus root and Smilax glabra rhizome is used to treat cancer patients in Sri Lanka. However, the anti-carcinogenic properties of this decoction have not been experimentally confirmed. The purpose of this study was to determine whether the above decoction could protect against chemically induce hepatocarcinogenesis. Methods The effects of this decoction on diethylnitrosamine (DEN induced hepatocarcinogenesis were examined in male Wistar rats using the medium term bioassay system of Ito, based on a 2-step model of hepatocarcinogenesis. Rats were randomly divided into 6 groups of 10 each. Groups 1 to 4 were injected with DEN (200 mg/kg to initiate carcinogenesis. Twenty-four hours later groups 1 and 2 were administered the decoction at 4 g/kg body weight/day (dose 1 and 6 g/kg body weight/day (dose 2, respectively. Group 3 and group 4 were given distilled water instead of the decoction and a suspension of garlic powder (20 g/kg body weight/day in distilled water (positive control, respectively. Group 5 and 6 were injected with normal saline and twenty-four hours later group 5 was given distilled water (normal control while group 6 was given decoction dose 2 (decoction control. Oral feeding continued for two weeks after which all rats were subjected to 2/3 partial hepatectomy to promote carcinogenesis. Oral feeding continued for eight more weeks. At the end of the 10th week, rats were sacrificed and samples of livers taken for immunohistochemical studies. Carcinogenic potential was scored by comparing the number, area and staining intensity of glutathione S-transferase placental form (GST-P positive foci and the number of cells/cm2 of the positive foci in the livers of the six groups of rats. Results The number and area of DEN-mediated GST-P positive foci, number of cells/cm2 of foci and staining intensity of the foci were significantly (P > 0.001 reduced by the

  3. Nonalcoholic steatohepatitis induced by a high-fat diet promotes diethylnitrosamine initiated early hepatocarcinogenesis in rats

    Science.gov (United States)

    It has been suggested that patients with nonalcoholic steatohepatitis (NASH) are at a high risk for liver cancer. However, it is unknown whether high-fat diet induced NASH promotes hepatocarcinogenesis. In the present study, Sprague-Dawley rats were injected with a low dose of hepatic carcinogen die...

  4. Gene silencing of Nox4 by CpG island methylation during hepatocarcinogenesis in rats

    Science.gov (United States)

    López-Álvarez, Guadalupe S.; Wojdacz, Tomasz K.; García-Cuellar, Claudia M.; Monroy-Ramírez, Hugo C.; Rodríguez-Segura, Miguel A.; Pacheco-Rivera, Ruth A.; Valencia-Antúnez, Carlos A.; Cervantes-Anaya, Nancy; Soto-Reyes, Ernesto; Vásquez-Garzón, Verónica R.; Sánchez-Pérez, Yesennia; Villa-Treviño, Saúl

    2017-01-01

    ABSTRACT The association between the downregulation of genes and DNA methylation in their CpG islands has been extensively studied as a mechanism that favors carcinogenesis. The objective of this study was to analyze the methylation of a set of genes selected based on their microarray expression profiles during the process of hepatocarcinogenesis. Rats were euthanized at: 24 h, 7, 11, 16 and 30 days and 5, 9, 12 and 18 months post-treatment. We evaluated the methylation status in the CpG islands of four deregulated genes (Casp3, Cldn1, Pex11a and Nox4) using methylation-sensitive high-resolution melting technology for the samples obtained from different stages of hepatocarcinogenesis. We did not observe methylation in Casp3, Cldn1 or Pex11a. However, Nox4 exhibited altered methylation patterns, reaching a maximum of 10%, even during the early stages of hepatocarcinogenesis. We observed downregulation of mRNA and protein of Nox4 (97.5% and 40%, respectively) after the first carcinogenic stimulus relative to the untreated samples. Our results suggest that Nox4 downregulation is associated with DNA methylation of the CpG island in its promoter. We propose that methylation is a mechanism that can silence the expression of Nox4, which could contribute to the acquisition of neoplastic characteristics during hepatocarcinogenesis in rats. PMID:27895046

  5. Sympathetic nervous system promotes hepatocarcinogenesis by modulating inflammation through activation of alpha1-adrenergic receptors of Kupffer cells.

    Science.gov (United States)

    Huan, Hong-Bo; Wen, Xu-Dong; Chen, Xue-Jiao; Wu, Lin; Wu, Li-Li; Zhang, Liang; Yang, Da-Peng; Zhang, Xia; Bie, Ping; Qian, Cheng; Xia, Feng

    2017-01-01

    The sympathetic nervous system (SNS) is known to play a significant role in tumor initiation and metastasis. Hepatocellular carcinoma (HCC) frequently occurs in cirrhotic livers after chronic inflammation, and the SNS is hyperactive in advanced liver cirrhosis. However, it remains unclear whether the SNS promotes hepatocarcinogenesis by modulating chronic liver inflammation. In this study, a retrospective pathological analysis and quantification of sympathetic nerve fiber densities (tyrosine hydroxylase, TH(+)) in HCC patients, and diethylnitrosamine (DEN)-induced hepatocarcinogenesis in rats were performed. Our data showed that high density of sympathetic nerve fibers and α1-adrenergic receptors (ARs) of Kupffer cells (KCs) were associated with a poor prognosis of HCC. Sympathetic denervation or blocking of α1-ARs decreased DEN-induced HCC incidence and tumor development. In addition, synergistic effects of interleukin-6 (IL-6) and transforming growth factor-beta (TGF-β) in hepatocarcinogenesis were observed. The suppression of the SNS reduced IL-6 and TGF-β expression, which suppressed hepatocarcinogenesis, and KCs play a key role in this process. After the ablation of KCs, IL-6 and TGF-β expression and the development of HCC were inhibited. This study demonstrates that sympathetic innervation is crucial for hepatocarcinogenesis and that the SNS promotes hepatocarcinogenesis by activating α1-ARs of KCs to boost the activation of KCs and to maintain the inflammatory microenvironment. These results indicate that sympathetic denervation or α1-ARs blockage may represent novel treatment approaches for HCC.

  6. Valerian inhibits rat hepatocarcinogenesis by activating GABA(A receptor-mediated signaling.

    Directory of Open Access Journals (Sweden)

    Anna Kakehashi

    Full Text Available Valerian is widely used as a traditional medicine to improve the quality of sleep due to interaction of several active components with the γ-aminobutyric acid (GABA A receptor (GABA(AR system. Recently, activation of GABA signaling in stem cells has been reported to suppress cell cycle progression in vivo. Furthermore, possible inhibitory effects of GABA(AR agonists on hepatocarcinogenesis have been reported. The present study was performed to investigate modulating effects of Valerian on hepatocarcinogenesis using a medium-term rat liver bioassay. Male F344 rats were treated with one of the most powerful Valerian species (Valeriana sitchensis at doses of 0, 50, 500 and 5000 ppm in their drinking water after initiation of hepatocarcinogenesis with diethylnitrosamine (DEN. Formation of glutathione S-transferase placental form positive (GST-P(+ foci was significantly inhibited by Valerian at all applied doses compared with DEN initiation control rats. Generation of 8-hydroxy-2'-deoxyguanosine in the rat liver was significantly suppressed by all doses of Valerian, likely due to suppression of Nrf2, CYP7A1 and induction of catalase expression. Cell proliferation was significantly inhibited, while apoptosis was induced in areas of GST-P(+ foci of Valerian groups associated with suppression of c-myc, Mafb, cyclin D1 and induction of p21(Waf1/Cip1, p53 and Bax mRNA expression. Interestingly, expression of the GABA(AR alpha 1 subunit was observed in GST-P(+ foci of DEN control rats, with significant elevation associated with Valerian treatment. These results indicate that Valerian exhibits inhibitory effects on rat hepatocarcinogenesis by inhibiting oxidative DNA damage, suppressing cell proliferation and inducing apoptosis in GST-P(+ foci by activating GABA(AR-mediated signaling.

  7. Gut-liver axis plays a role in hepatocarcinogenesis of patients with Crohn's disease

    Institute of Scientific and Technical Information of China (English)

    Shu-Mei Zheng; De-Jun Cui; Qin Ouyang

    2011-01-01

    The development of hepatocellular carcinoma (HCC) is attributed to several factors, including chronic viral infection, alcohol consumption, exposure to aflatoxin B1 and metabolic disorders. Several recent reports have shown that HCC can occur in patients with longstanding Crohn's disease (CD) in the absence of other underlying high-risk liver diseases. There may be an association between CD and hepatocarcinogenesis, however, the precise mechanism for this requires further investigations.

  8. Progressive Enrichment of Stemness Features and Tumor Stromal Alterations in Multistep Hepatocarcinogenesis.

    Science.gov (United States)

    Yoo, Jeong Eun; Kim, Young-Joo; Rhee, Hyungjin; Kim, Haeryoung; Ahn, Ei Yong; Choi, Jin Sub; Roncalli, Massimo; Park, Young Nyun

    2017-01-01

    Cancer stem cells (CSCs), a subset of tumor cells, contribute to an aggressive biological behavior, which is also affected by the tumor stroma. Despite the role of CSCs and the tumor stroma in hepatocellular carcinoma (HCC), features of stemness have not yet been studied in relation to tumor stromal alterations in multistep hepatocarcinogenesis. We investigated the expression status of stemness markers and tumor stromal changes in B viral carcinogenesis, which is the main etiology of HCC in Asia. Stemness features of tumoral hepatocytes (EpCAM, K19, Oct3/4, c-KIT, c-MET, and CD133), and tumor stromal cells expressing α-smooth muscle actin (α-SMA), CD68, CD163, and IL-6 were analyzed in 36 low grade dysplastic nodules (DNs), 48 high grade DNs, 30 early HCCs (eHCCs), and 51 progressed HCCs (pHCCs) by immunohistochemistry or real-time PCR. Stemness features (EpCAM and K19 in particular) were progressively acquired during hepatocarcinogenesis in combination with enrichment of stromal cells (CAFs, TAMs, IL-6+ cells). Stemness features were seen sporadically in DNs, more consistent in eHCCs, and peaked in pHCCs. Likewise, stromal cells were discernable in DNs, showed up as consistent cell densities in eHCCs and peaked in pHCCs. The stemness features and tumor stromal alterations also peaked in less differentiated or larger HCCs. In conclusion, progression of B viral multistep hepatocarcinogenesis is characterized by an enrichment of stemness features of neoplastic hepatocytes and a parallel alteration of the tumor stroma. The modulation of neoplastic hepatocytes and stromal cells was at low levels in precancerous lesions (DNs), consistently increased in incipient cancer (eHCCs) and peaked in pHCCs. Thus, in B viral hepatocarcinogenesis, interactions between CSCs and the tumor stroma, although starting early, seem to play a major role in tumor progression.

  9. Molecular aspects and chemoprevention of dimethylaminoazobenzene-induced hepatocarcinogenesis: A review.

    Science.gov (United States)

    Thomas, Nisha Susan; George, Kiran; Namasivayam, Nalini

    2016-01-01

    The lipophilic azo dye dimethylaminoazobenzene (DAB) is a potent hepatocarcinogen accounted as a group-2B carcinogen causing risk to humans. DAB is commonly used as a coloring agent in food, pharmaceuticals, beverages, soap and polishes. The exploration of DAB-induced hepatocarcinogenesis in animal models helped to an extent to perceive the histological, biochemical and molecular mechanisms of DAB carcinogenesis and also the severity of DAB exposure to humans. In experimental animal models, it is well-proved that the procarcinogen DAB is predominantly metabolized by cytochrome P450 enzymes giving rise to the formation of toxic electrophiles and reactive oxygen species (ROS), which further forms DNA adducts leading to the development of hepatic tumors. Recently, research evidence suggests that dietary phytochemicals and plant polyphenols are promising agents to control the incidence of DAB-induced hepatocarcinogenesis by preventing the generation of toxic electrophiles and ROS thereby inhibiting the formation of DNA adducts. This review highlights the role of specific dietary factors, biotransformation of DAB, phenotypic and genotypic alterations, and significance of certain chemopreventive agents against DAB-induced hepatocarcinogenesis.

  10. Differential expression of genes during aflatoxin B1-induced hepatocarcinogenesis in tree shrews

    Institute of Scientific and Technical Information of China (English)

    Yuan Li; Dan Luo; Hui-Fen Yue; Li-Sheng Zhang; Jian-Ren Gu; Da-Fang Wan; Jian-Jia Su; Ji Cao; Chao Ou; Xiao-Kun Qiu; Ke-Chen Ban; Chun Yang; Liu-Liang Qin

    2004-01-01

    AIM: Through exploring the regulation of gene expression during hepatocarcinogenesis induced by aflatoxin B1 (AFB1),to find out the responsible genes for hepatocellular carcinoma (HCC) and to further understand the underlying molecular mechanism.METHODS: Tree shrews ( 7upaia belangeri chinensis)were treated with or without AFB1 for about 90 weeks. Liver biopsies were performed regularly during the animal experiment. Eight shares of total RNA were respectively isolated from 2 HCC tissues, 2 HCC-surrounding noncancerous liver tissues, 2 biopsied tissues at the early stage (30th week) of the experiment from the same animals as above, 1 mixed sample of three liver tissues biopsied at the beginning (0th week) of the experiment, and another 1 mixed sample of two liver tissues from the untreated control animals biopsied at the 90th week of the experiment. The samples were then tested with the method of AtlasTM cDNA microarray assay. The levels of gene expression in these tissues taken at different time points during hepatocarcinogenesis were compared.RESULTS: The profiles of differently expressed genes were quite different in different ways of comparison. At the same period of hepatocarcinogenesis, the genes in the same function group usually had the same tendency for up- or down-regulation. Among the checked 588 genes that were known to be related to human cancer, 89 genes (15.1%) were recognized as "important genes" because they showed frequent changes in different ways of comparison. The differentially expressed genes during hepatocarcinogenesis could be classified into four categories: genes up-regulated in HCC tissue, genes with similar expressing levels in both HCC and HCC-surrounding liver tissues which were higher than that in the tissues prior to the development of HCC,genes down-regulated in HCC tissue, and genes up-regulated prior to the development of HCC but down-regulated after the development of HCC.CONCLUSION: A considerable number of genes could change

  11. Differential expression of genes during aflatoxin B1-induced hepatocarcinogenesis in tree shrews

    Science.gov (United States)

    Li, Yuan; Wan, Da-Fang; Su, Jian-Jia; Cao, Ji; Ou, Chao; Qiu, Xiao-Kun; Ban, Ke-Chen; Yang, Chun; Qin, Liu-Liang; Luo, Dan; Yue, Hui-Fen; Zhang, Li-Sheng; Gu, Jian-Ren

    2004-01-01

    AIM: Through exploring the regulation of gene expression during hepatocarcinogenesis induced by aflatoxin B1 (AFB1), to find out the responsible genes for hepatocellular carcinoma (HCC) and to further understand the underlying molecular mechanism. METHODS: Tree shrews (Tupaia belangeri chinensis) were treated with or without AFB1 for about 90 weeks. Liver biopsies were performed regularly during the animal experiment. Eight shares of total RNA were respectively isolated from 2 HCC tissues, 2 HCC-surrounding non-cancerous liver tissues, 2 biopsied tissues at the early stage (30th week) of the experiment from the same animals as above, 1 mixed sample of three liver tissues biopsied at the beginning (0th week) of the experiment, and another 1 mixed sample of two liver tissues from the untreated control animals biopsied at the 90th week of the experiment. The samples were then tested with the method of AtlasTM cDNA microarray assay. The levels of gene expression in these tissues taken at different time points during hepatocarcinogenesis were compared. RESULTS: The profiles of differently expressed genes were quite different in different ways of comparison. At the same period of hepatocarcinogenesis, the genes in the same function group usually had the same tendency for up- or down-regulation. Among the checked 588 genes that were known to be related to human cancer, 89 genes (15.1%) were recognized as “important genes” because they showed frequent changes in different ways of comparison. The differentially expressed genes during hepatocarcinogenesis could be classified into four categories: genes up-regulated in HCC tissue, genes with similar expressing levels in both HCC and HCC-surrounding liver tissues which were higher than that in the tissues prior to the development of HCC, genes down-regulated in HCC tissue, and genes up-regulated prior to the development of HCC but down-regulated after the development of HCC. CONCLUSION: A considerable number of genes could

  12. Deregulation of Epigenetic Mechanisms by the Hepatitis B Virus X Protein in Hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Ourania M. Andrisani

    2013-03-01

    Full Text Available This review focuses on the significance of deregulation of epigenetic mechanisms by the hepatitis B virus (HBV X protein in hepatocarcinogenesis and HBV replication. Epigenetic mechanisms, DNA methylation, and specific histone modifications, e.g., trimethylation of H3 on lysine-27 or lysine-4, maintain ‘cellular memory’ by silencing expression of lineage-inducing factors in stem cells and conversely, of pluripotency factors in differentiated cells. The X protein has been reported to induce expression of DNA methyltransferases (DNMTs, likely promoting epigenetic changes during hepatocarcinogenesis. Furthermore, in cellular and animal models of X-mediated oncogenic transformation, protein levels of chromatin modifying proteins Suz12 and Znf198 are down-regulated. Suz12 is essential for the Polycomb Repressive Complex 2 (PRC2 mediating the repressive trimethylation of H3 on lysine-27 (H3K27me3. Znf198, stabilizes the LSD1-CoREST-HDAC complex that removes, via lysine demethylase1 (LSD1, the activating trimethylation of H3 on lysine-4 (H3K4me3. Down-regulation of Suz12 also occurs in liver tumors of woodchucks chronically infected by woodchuck hepatitis virus, an animal model recapitulating HBV-mediated hepatocarcinogenesis in humans. Significantly, subgroups of HBV-induced liver cancer re-express hepatoblast and fetal markers, and imprinted genes, suggesting hepatocyte reprogramming during oncogenic transformation. Lastly, down-regulation of Suz12 and Znf198 enhances HBV replication. Collectively, these observations suggest deregulation of epigenetic mechanisms by HBV X protein influences both the viral cycle and the host cell.

  13. LED-roulette: LED's vervangen balletje

    NARCIS (Netherlands)

    Goossens, P.

    2007-01-01

    Iedereen waagt wel eens een gokje, in een loterij of misschien ook in een casino. Wie droomt er immers niet van om op een gemakkelijke manier rijk te worden? Met de hier beschreven LED-roulette valt weliswaar weinig te winnen, maar het is wel een uitstekende manier om het roulettespel thuis te beoef

  14. New insights into BaP-induced toxicity: role of major metabolites in transcriptomics and contribution to hepatocarcinogenesis.

    Science.gov (United States)

    Souza, Terezinha; Jennen, Danyel; van Delft, Joost; van Herwijnen, Marcel; Kyrtoupolos, Soterios; Kleinjans, Jos

    2016-06-01

    Benzo(a)pyrene (BaP) is a ubiquitous carcinogen resulting from incomplete combustion of organic compounds and also present at high levels in cigarette smoke. A wide range of biological effects has been attributed to BaP and its genotoxic metabolite BPDE, but the contribution to BaP toxicity of intermediary metabolites generated along the detoxification path remains unknown. Here, we report for the first time how 3-OH-BaP, 9,10-diol and BPDE, three major BaP metabolites, temporally relate to BaP-induced transcriptomic alterations in HepG2 cells. Since BaP is also known to induce AhR activation, we additionally evaluated TCDD to source the expression of non-genotoxic AhR-mediated patterns. 9,10-Diol was shown to activate several transcription factor networks related to BaP metabolism (AhR), oxidative stress (Nrf2) and cell proliferation (HIF-1α, AP-1) in particular at early time points, while BPDE influenced expression of genes involved in cell energetics, DNA repair and apoptotic pathways. Also, in order to grasp the role of BaP and its metabolites in chemical hepatocarcinogenesis, we compared expression patterns from BaP(-metabolites) and TCDD to a signature set of approximately nine thousand gene expressions derived from hepatocellular carcinoma (HCC) patients. While transcriptome modulation by TCDD appeared not significantly related to HCC, BaP and BPDE were shown to deregulate metastatic markers via non-genotoxic and genotoxic mechanisms and activate inflammatory pathways (NF-κβ signaling, cytokine-cytokine receptor interaction). BaP also showed strong repression of genes involved in cholesterol and fatty acid biosynthesis. Altogether, this study provides new insights into BaP-induced toxicity and sheds new light onto its mechanism of action as a hepatocarcinogen.

  15. Inhibition of Diethylnitrosamine-Induced Hepatocarcinogenesis in Mice by a High Dietary Protein Intake.

    Science.gov (United States)

    Shou, Qiyang; Chen, Fangming; Cai, Yueqin; Zhang, Shanxin; Tu, Jue; Zhang, Lizong; Wang, Dejun; Wang, Jianchao; Chen, Minli; Fu, Huiying

    2015-01-01

    Epidemiological and experimental evidence supports the key role of diet in the development of many types of cancer. Recent studies have suggested that dietary modifications may be beneficial for individuals at high risk for hepatocellular carcinoma (HCC). In this study, we investigated the effect of a high-protein (HP; 20% casein) dietondiethylnitrosamine (DEN)-induced hepatocarcinogenesis. Mice were given free access to water with 30 μg/ml DEN and fed a normal or HP diet for 22 wk. The results showed mice consuming HP diets had reduced mortality rates and body weights and lower hepatic enzyme activity compared to DEN-treated mice on a normal diet. HP consumption also promoted collagen accumulation in the liver, and reduced numbers of proliferating hepatocytes and infiltrating inflammatory cells, as well as decreased expression of inflammatory factor interleukin-1β, and nuclear factor κB activation. These data indicate that HP diets can inhibit DEN-induced hepatocarcinogenesis via suppression of the inflammatory response and provide a new evidence for the dietary management of clinical patients with hepatocellular carcinoma.

  16. The Role of NF-κB in PPARα-Mediated Hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Howard P. Glauert

    2008-01-01

    Full Text Available In this review, the role of NF-κB in the induction of hepatocarcinogenesis by peroxisome proliferators is examined. The administration of peroxisome proliferators for more than a three-day period leads to the activation of NF-κB in the livers of rats and mice. On the other hand, peroxisome proliferator activated receptor-α (PPARα activation in non-hepatic tissues can lead to the inhibition of NF-κB activation. Several lines of evidence support the hypothesis that the activation of NF-κB by peroxisome proliferators in the liver is mediated by oxidative stress. The role of NF-κB in peroxisome proliferator-induced hepatocarcinogenesis has been examined using NF-κB knockout models. Specifically, the induction of cell proliferation and the promotion of liver carcinogenesis are inhibited in mice lacking the p50 subunit of NF-κB. Overall, the activation of NF-κB appears to be important in the carcinogenic activity of peroxisome proliferators.

  17. Inhibition by gomisin A, a lignan compound, of hepatocarcinogenesis by 3'-methyl-4-dimethylaminoazobenzene in rats.

    Science.gov (United States)

    Ohtaki, Y; Nomura, M; Hida, T; Miyamoto, K; Kanitani, M; Aizawa, T; Aburada, M

    1994-06-01

    The effects of gomisin A, a lignan compound of Schizandra fruits, on hepatocarcinogenesis induced by 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) in rats were investigated. Gomisin A inhibited both increases of the number and size of glutathione S-transferase placental form (GST-P)-positive foci, a marker enzyme of preneoplasm, and the population of diploid nuclei, as a proliferative state of hepatocytes, in the liver from rats simultaneously treated with 3'-MeDAB. Gomisin A increased GST activity in the liver, by raising the level of GST 1 and 2 isozymes. 3'-MeDAB increased GST activity and GST-P expression. This high level of GST-P induced by 3'-MeDAB was suppressed by additional treatment with gomisin A. In an experiment on simultaneous treatment, gomisin A increased the biliary excretion of 3'-MeDAB-related aminoazo dyes and decreased the content in the liver of rats fed with 0.06%-3'-MeDAB containing diet. In an experiment on pretreatment with 3'-MeDAB, even though no aminoazo dye was detectable in the liver or bile 2-weeks after cessation of 3'-MeDAB-feeding, gomisin A showed a tendency to reduce the preneoplastic changes of increases in GST-P positive foci and diploid nuclei in the liver. These results suggest that gomisin A inhibits the hepatocarcinogenesis induced by 3'-MeDAB by enhancing the excretion of the carcinogen from the liver and by reversing the normal cytokinesis.

  18. Metformin inhibits early stage diethylnitrosamine‑induced hepatocarcinogenesis in rats.

    Science.gov (United States)

    Jo, Woori; Yu, Eun-Sil; Chang, Minsun; Park, Hyun-Kyu; Choi, Hyun-Ji; Ryu, Jae-Eun; Jang, Sungwoong; Lee, Hyo-Ju; Jang, Ja-June; Son, Woo-Chan

    2016-01-01

    Antitumor effects of metformin have recently emerged despite its original use for type II diabetes. In the present study, the effects of metformin on the development and recurrence of hepatocellular carcinoma (HCC) were investigated using the diethylnitrosamine (DEN)‑induced rat model of HCC. Tumor foci were characterized by gross examination and by histopathological characteristics, including proliferation, hepatic progenitor cell content and the expression of hepatocarcinoma‑specific molecular markers. Potential target molecules of metformin were investigated to determine the molecular mechanism underlying the inhibitory effects of metformin on chemically induced liver tumorigenesis. The antitumor effects of metformin were increased by the reduction of surface nodules and decreased the incidence of altered hepatocellular foci, hepatocellular adenoma and carcinoma. Also, decreased expression levels of glutathione S‑transferase placental form, proliferating cell nuclear antigen and cytokeratin 8 described the inhibitory effects of metformin on HCC. In the present study, Wistar rats receiving treatment with DEN were administered metformin for 16 weeks. In addition, metformin suppressed liver tumorigenesis via an AMPK‑dependent pathway. These results suggested that metformin has promising effects on the early stage of HCC in rats. Therefore, metformin may be used for the prevention of HCC recurrence following primary chemotherapy for HCC and/or for high‑risk patients, including chronic hepatitis and cirrhosis.

  19. Liver-specific expressions of HBx and src in the p53 mutant trigger hepatocarcinogenesis in zebrafish.

    Directory of Open Access Journals (Sweden)

    Jeng-Wei Lu

    Full Text Available Hepatocarcinogenesis is a multistep process that starts from fatty liver and transitions to fibrosis and, finally, into cancer. Many etiological factors, including hepatitis B virus X antigen (HBx and p53 mutations, have been implicated in hepatocarcinogenesis. However, potential synergistic effects between these two factors and the underlying mechanisms by which they promote hepatocarcinogenesis are still unclear. In this report, we show that the synergistic action of HBx and p53 mutation triggers progressive hepatocellular carcinoma (HCC formation via src activation in zebrafish. Liver-specific expression of HBx in wild-type zebrafish caused steatosis, fibrosis and glycogen accumulation. However, the induction of tumorigenesis by HBx was only observed in p53 mutant fish and occurred in association with the up-regulation and activation of the src tyrosine kinase pathway. Furthermore, the overexpression of src in p53 mutant zebrafish also caused hyperplasia, HCC, and sarcomatoid HCC, which were accompanied by increased levels of the signaling proteins p-erk, p-akt, myc, jnk1 and vegf. Increased expression levels of lipogenic factors and the genes involved in lipid metabolism and glycogen storage were detected during the early stages of hepatocarcinogenesis in the HBx and src transgenic zebrafish. The up-regulation of genes involved in cell cycle regulation, tumor progression and other molecular hallmarks of human liver cancer were found at later stages in both HBx and src transgenic, p53 mutant zebrafish. Together, our study demonstrates that HBx and src overexpression induced hepatocarcinogenesis in p53 mutant zebrafish. This phenomenon mimics human HCC formation and provides potential in vivo platforms for drug screening for therapies for human liver cancer.

  20. Large area LED package

    Science.gov (United States)

    Goullon, L.; Jordan, R.; Braun, T.; Bauer, J.; Becker, F.; Hutter, M.; Schneider-Ramelow, M.; Lang, K.-D.

    2015-03-01

    Solid state lighting using LED-dies is a rapidly growing market. LED-dies with the needed increasing luminous flux per chip area produce a lot of heat. Therefore an appropriate thermal management is required for general lighting with LEDdies. One way to avoid overheating and shorter lifetime is the use of many small LED-dies on a large area heat sink (down to 70 μm edge length), so that heat can spread into a large area while at the same time light also appears on a larger area. The handling with such small LED-dies is very difficult because they are too small to be picked with common equipment. Therefore a new concept called collective transfer bonding using a temporary carrier chip was developed. A further benefit of this new technology is the high precision assembly as well as the plane parallel assembly of the LED-dies which is necessary for wire bonding. It has been shown that hundred functional LED-dies were transferred and soldered at the same time. After the assembly a cost effective established PCB-technology was applied to produce a large-area light source consisting of many small LED-dies and electrically connected on a PCB-substrate. The top contacts of the LED-dies were realized by laminating an adhesive copper sheet followed by LDI structuring as known from PCB-via-technology. This assembly can be completed by adding converting and light forming optical elements. In summary two technologies based on standard SMD and PCB technology have been developed for panel level LED packaging up to 610x 457 mm2 area size.

  1. Antineoplastic potential of Bryophyllum pinnatum lam. on chemically induced hepatocarcinogenesis in rats

    Directory of Open Access Journals (Sweden)

    Muhammad Afzal

    2013-01-01

    Full Text Available Background: Bryophyllum pinnatum Lam. used in folk medicine in tropical Africa, tropical America, India, China and Australia contains a wide range of active compounds, well known for their haemostatic and wound-healing properties. Objective: The present study was designed to evaluate the effect of Bryophyllum pinnatum Lam. on N-diethylnitrosamine (DENA-induced hepatic injury in rats. Material and Methods: The aerial part of B. pinnatum aqueous and ethanolic extract was prepared in doses of 250 mg/kg and 500 mg/kg. Hepatic injury was induced by DENA. Acute toxicity was also carried out. Result: Treatment with different doses of ethanolic extract of B. Pinnatum (250 mg/kg, p.o. was not significantly able to treat the liver injury induced by DENA, but 500 mg/kg dose of ethanolic extract of B. Pinnatum protects the liver slightly. Treatment with different doses of aqueous extract of B. Pinnatum (250 and 500 mg/kg, p.o. significantly (PFNx01<0.05; PFNx08<0.01 and PFNx18<0.001 treated the liver injury induced by DENA. Conclusion: It may be inferred from the present study that the hepatoprotective activities of the aqueous extract of B. Pinnatum leaves in DENA-induced hepatotoxicity may involve its antioxidant or oxidative free radical scavenging activities by alleviating lipid peroxidation through scavenging of free radicals, or by enhancing the activity of antioxidants.

  2. High-quality uniaxial In(x)Ga(1-x)N/GaN multiple quantum well (MQW) nanowires (NWs) on Si(111) grown by metal-organic chemical vapor deposition (MOCVD) and light-emitting diode (LED) fabrication.

    Science.gov (United States)

    Ra, Yong-Ho; Navamathavan, R; Park, Ji-Hyeon; Lee, Cheul-Ro

    2013-03-01

    This article describes the growth and device characteristics of vertically aligned high-quality uniaxial p-GaN/InxGa1-xN/GaN multiple quantum wells (MQW)/n-GaN nanowires (NWs) on Si(111) substrates grown by metal-organic chemical vapor deposition (MOCVD) technique. The resultant nanowires (NWs), with a diameter of 200-250 nm, have an average length of 2 μm. The feasibility of growing high-quality NWs with well-controlled indium composition MQW structure is demonstrated. These resultant NWs grown on Si(111) substrates were utilized for fabricating vertical-type light-emitting diodes (LEDs). The steep and intense photoluminescence (PL) and cathodoluminescence (CL) spectra are observed, based on the strain-free NWs on Si(111) substrates. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that the MQW NWs are grown along the c-plane with uniform thickness. The current-voltage (I-V) characteristics of these NWs exhibited typical p-n junction LEDs and showed a sharp onset voltage at 2.75 V in the forward bias. The output power is linearly increased with increasing current. The result indicates that the pulsed MOCVD technique is an effective method to grow uniaxial p-GaN/InxGa1-xN/GaN MQW/n-GaN NWs on Si(111), which is more advantageous than other growth techniques, such as molecular beam epitaxy. These results suggest the uniaxial NWs are promising to allow flat-band quantum structures, which can enhance the efficiency of LEDs.

  3. LEDs Are Diodes.

    Science.gov (United States)

    Lisensky, George C.; Condren, S. Michael; Widstrand, Cynthia G.; Breitzer, Jonathan; Ellis, Arthur B.

    2001-01-01

    Describes an activity comparing incandescent bulbs and LEDs powered by dc and ac voltage sources to illustrate properties of matter and the interactions of energy and matter. Includes both instructor information and student activity sheet. (Author/YDS)

  4. Modeling LED street lighting.

    Science.gov (United States)

    Moreno, Ivan; Avendaño-Alejo, Maximino; Saucedo-A, Tonatiuh; Bugarin, Alejandra

    2014-07-10

    LED luminaires may deliver precise illumination patterns to control light pollution, comfort, visibility, and light utilization efficiency. Here, we provide simple equations to determine how the light distributes in the streets. In particular, we model the illuminance spatial distribution as a function of Cartesian coordinates on a floor, road, or street. The equations show explicit dependence on the luminary position (pole height and arm length), luminary angle (fixture tilt), and the angular intensity profile (radiation pattern) of the LED luminary. To achieve this, we propose two mathematical representations to model the sophisticated intensity profiles of LED luminaries. Furthermore, we model the light utilization efficiency, illumination uniformity, and veiling luminance of glare due to one or several LED streetlamps.

  5. RS-232 Led Board

    CERN Document Server

    Tskhvaradze, Vladimir

    2007-01-01

    This article demonstrates how to develop a Microchip PIC16F84 based device that supports RS-232 interface with PC. Circuit (LED Board) design and software development will be discussed. PicBasic Pro Compiler from microEngineering Labs, Inc. is used for PIC programming. Development of LED Board Control Console using C/C++ is also briefly discussed. The project requires basic work experience with Microchip PICs, serial communication and programming.

  6. Overexpression of a splice variant of DNA methyltransferase 3b, DNMT3b4, associated with DNA hypomethylation on pericentromeric satellite regions during human hepatocarcinogenesis

    OpenAIRE

    Saito, Yoshimasa; Kanai, Yae; Sakamoto, Michiie; Saito, Hidetsugu; Ishii, Hiromasa; Hirohashi, Setsuo

    2002-01-01

    DNA hypomethylation on pericentromeric satellite regions is an early and frequent event associated with heterochromatin instability during human hepatocarcinogenesis. A DNA methyltransferase, DNMT3b, is required for methylation on pericentromeric satellite regions during mouse development. To clarify the molecular mechanism underlying DNA hypomethylation on pericentromeric satellite regions during human hepatocarcinogenesis, we examined mutations of the DNMT3b gene and mRNA expression levels ...

  7. SCD1 Expression is dispensable for hepatocarcinogenesis induced by AKT and Ras oncogenes in mice.

    Directory of Open Access Journals (Sweden)

    Lei Li

    Full Text Available Increased de novo lipogenesis is one of the major metabolic events in cancer. In human hepatocellular carcinoma (HCC, de novo lipogenesis has been found to be increased and associated with the activation of AKT/mTOR signaling. In mice, overexpression of an activated form of AKT results in increased lipogenesis and hepatic steatosis, ultimately leading to liver tumor development. Hepatocarcinogenesis is dramatically accelerated when AKT is co-expressed with an oncogenic form of N-Ras. SCD1, the major isoform of stearoyl-CoA desaturases, catalyzing the conversion of saturated fatty acids (SFA into monounsaturated fatty acids (MUFA, is a key enzyme involved in de novo lipogenesis. While many studies demonstrated the requirement of SCD1 for tumor cell growth in vitro, whether SCD1 is necessary for tumor development in vivo has not been previously investigated. Here, we show that genetic ablation of SCD1 neither inhibits lipogenesis and hepatic steatosis in AKT-overexpressing mice nor affects liver tumor development in mice co-expressing AKT and Ras oncogenes. Molecular analysis showed that SCD2 was strongly upregulated in liver tumors from AKT/Ras injected SCD1(-/- mice. Noticeably, concomitant silencing of SCD1 and SCD2 genes was highly detrimental for the growth of AKT/Ras cells in vitro. Altogether, our study provides the evidence, for the first time, that SCD1 expression is dispensable for AKT/mTOR-dependent hepatic steatosis and AKT/Ras-induced hepatocarcinogenesis in mice. Complete inhibition of stearoyl-CoA desaturase activity may be required to efficiently suppress liver tumor development.

  8. Identification of rtl1, a retrotransposon-derived imprinted gene, as a novel driver of hepatocarcinogenesis.

    Directory of Open Access Journals (Sweden)

    Jesse D Riordan

    2013-04-01

    Full Text Available We previously utilized a Sleeping Beauty (SB transposon mutagenesis screen to discover novel drivers of HCC. This approach identified recurrent mutations within the Dlk1-Dio3 imprinted domain, indicating that alteration of one or more elements within the domain provides a selective advantage to cells during the process of hepatocarcinogenesis. For the current study, we performed transcriptome and small RNA sequencing to profile gene expression in SB-induced HCCs in an attempt to clarify the genetic element(s contributing to tumorigenesis. We identified strong induction of Retrotransposon-like 1 (Rtl1 expression as the only consistent alteration detected in all SB-induced tumors with Dlk1-Dio3 integrations, suggesting that Rtl1 activation serves as a driver of HCC. While previous studies have identified correlations between disrupted expression of multiple Dlk1-Dio3 domain members and HCC, we show here that direct modulation of a single domain member, Rtl1, can promote hepatocarcinogenesis in vivo. Overexpression of Rtl1 in the livers of adult mice using a hydrodynamic gene delivery technique resulted in highly penetrant (86% tumor formation. Additionally, we detected overexpression of RTL1 in 30% of analyzed human HCC samples, indicating the potential relevance of this locus as a therapeutic target for patients. The Rtl1 locus is evolutionarily derived from the domestication of a retrotransposon. In addition to identifying Rtl1 as a novel driver of HCC, our study represents one of the first direct in vivo demonstrations of a role for such a co-opted genetic element in promoting carcinogenesis.

  9. [LED lights in dermatology].

    Science.gov (United States)

    Noé, C; Pelletier-Aouizerate, M; Cartier, H

    2017-01-16

    The use in dermatology of light-emitting diodes (LEDs) continues to be surrounded by controversy. This is due mainly to poor knowledge of the physicochemical phases of a wide range of devices that are difficult to compare to one another, and also to divergences between irrefutable published evidence either at the level of in vitro studies or at the cellular level, and discordant clinical results in a variety of different indications: rejuvenation, acne, wound healing, leg ulcers, and cutaneous inflammatory or autoimmune processes. Therapeutic LEDs can emit wavelengths ranging from the ultraviolet, through visible light, to the near infrared (247-1300 nm), but only certain bands have so far demonstrated any real value. We feel certain that if this article remains factual, then readers will have a different, or at least more nuanced, opinion concerning the use of such LED devices in dermatology.

  10. LED system reliability

    NARCIS (Netherlands)

    Driel, W.D. van; Yuan, C.A.; Koh, S.; Zhang, G.Q.

    2011-01-01

    This paper presents our effort to predict the system reliability of Solid State Lighting (SSL) applications. A SSL system is composed of a LED engine with micro-electronic driver(s) that supplies power to the optic design. Knowledge of system level reliability is not only a challenging scientific ex

  11. Spectroradiometry for LED characterization

    DEFF Research Database (Denmark)

    Dam-Hansen, Carsten

    Radiospectroscopy is the absolute measurement of electromagnetic radiation within a specific wavelength range. For characterization of LED components, light sources and lamps we are interested in absolute measurement of the spectral power distribution, SPD, in the visible and near infrared region...

  12. MCM3AP,a Novel HBV Integration Site in Hepatocellular Carcinoma and Its Implication in Hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    王晶; 林菊生; 常莹; 黎培元; 杨玉珍

    2010-01-01

    A novel HBV integration site involved in hepatocarcinogenesis was investigated. The HBV DNA integration sites were detected by Alu-PCR in hepatocellular carcinoma tissues, matched surrounding liver tissues in 30 patients with hepatitis B-related hepatocellular carcinoma (HCC) and 3 cases of normal liver tissues. The integration sites and flanking sequences in human genome were sequenced and blasted, and the expression of integrated HBV genes was determined by reverse transcriptase-polymerase chain reaction ...

  13. Deleted in liver cancer 2 (DLC2 was dispensable for development and its deficiency did not aggravate hepatocarcinogenesis.

    Directory of Open Access Journals (Sweden)

    Tai On Yau

    Full Text Available DLC2 (deleted in liver cancer 2, a Rho GTPase-activating protein, was previously shown to be underexpressed in human hepatocellular carcinoma and has tumor suppressor functions in cell culture models. We generated DLC2-deficient mice to investigate the tumor suppressor role of DLC2 in hepatocarcinogenesis and the function of DLC2 in vivo. In this study, we found that, unlike homologous DLC1, which is essential for embryonic development, DLC2 was dispensable for embryonic development and DLC2-deficient mice could survive to adulthood. We also did not observe a higher incidence of liver tumor formation or diethylnitrosamine (DEN-induced hepatocarcinogenesis in DLC2-deficient mice. However, we observed that DLC2-deficient mice were smaller and had less adipose tissue than the wild type mice. These phenotypes were not due to reduction of cell size or defect in adipogenesis, as observed in the 190B RhoGAP-deficient mouse model. Together, these results suggest that deficiency in DLC2 alone does not enhance hepatocarcinogenesis.

  14. Thermal management for LED applications

    CERN Document Server

    Poppe, András

    2014-01-01

    Thermal Management for LED Applications provides state-of-the-art information on recent developments in thermal management as it relates to LEDs and LED-based systems and their applications. Coverage begins with an overview of the basics of thermal management including thermal design for LEDs, thermal characterization and testing of LEDs, and issues related to failure mechanisms and reliability and performance in harsh environments. Advances and recent developments in thermal management round out the book with discussions on advances in TIMs (thermal interface materials) for LED applications, advances in forced convection cooling of LEDs, and advances in heat sinks for LED assemblies. This book also: Presents a comprehensive overview of the basics of thermal management as it relates to LEDs and LED-based systems Discusses both design and thermal management considerations when manufacturing LEDs and LED-based systems Covers reliability and performance of LEDs in harsh environments Has a hands-on applications a...

  15. Design of Knight LED system

    Science.gov (United States)

    Zheng, Wen; Lou, Yuna; Xiao, Zhihong

    2010-02-01

    This design introduces a used car on the design of LED decorative light strip. This LED named Knight LED. In This system we use ATMEGA8 as the Master MCU Chip. Through the microcontroller to implement the wireless remote control receiver and the LED lights of different modes of switching, different brightness control. Also we use ULN2803 as the LED driver.

  16. Alteration of p53and p21 during hepatocarcinogenesis in shrews

    Institute of Scientific and Technical Information of China (English)

    Jian-Jia Su; Rui-Qi Yang; Ke-Chen Ban; Yuan Li; Liu-Liang Qin; Hui-Yun Wang; Chun Yang; Chao Ou; Xiao-Xian Duan; Young-Lk Lee

    2004-01-01

    AIM: To investigate p53 mutation and p21 expression in hepatocarcinogenesis induced by hepatitis B virus (HBV)and aflatoxin B1 (AFB1) in tree shrews, and to reveal the role of these genes in hepatocarcinogenesis.METHODS: Tree shrews were divided into four groups:group A, those infected with HBV and fed with AFB1 (n = 39);group B, those infected with HBV alone (n = 28); group C,those fed with AFB1 alone (n = 29); and group D, normal controls (n = 20). The tree shrews underwent liver biopsies once every 15 wk. Expression of p53 and p21 proteins and genes in the biopsies and tumor tissues of the experimental tree shrews was detected, respectively, by immunohistochemistry,and by Southern blottdng and reverse transcription-polymerase chain reaction and sequencing.RESULTS: The incidence of hepatocellular carcinomas (HCC) was higher in group A (66.7%) than that in group B (3.57%) and C (30%). The time of HCC occurrence was also earlier in group A than that in group C (120.0±16.6 wk vs 153.3±5.8 wk, respectively, P<0.01). p53 protein was not detected by immunohistochemistry in all groups before the 75th wk of the experiment. At the 105th wk, the positive rates fo p53 were 78.6%, 60% and 71.4% in groups A, B and C, respectively, which were significantly higher than that in group D (10%) (all P<0.05). An abnormal band of p53gene was observed in groups A and C. The mutation points of p53gene in tree shrews with HCC were at codons 275, 78 and 13. The nucleotide sequence and amino acid sequence of tree shrew's wild-type p53 showed 91.7%and 93.4% homologies with those of human p53,respectively. The immunopositivity for p21 was found before HCC development. The incidence of HCC was significantly higher in tree shrews that were positive for p21 than those negative for p21 (80.0% vs 11.0%, P<0.001).The incidence of HCC in p21 positive animals in group A was significantly higher than those positive for p21 in group C (P<0.05).CONCLUSION: A remarkable synergistic effect on HCC

  17. Exploration of Deregulated Long Non-Coding RNAs in Association with Hepatocarcinogenesis and Survival

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Jing, E-mail: js2182@cumc.columbia.edu [Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Medical Center, New York, NY 10032 (United States); Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032 (United States); Siegel, Abby B. [Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032 (United States); Department of Medicine, Columbia University Medical Center, New York, NY 10032 (United States); Remotti, Helen [Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032 (United States); Wang, Qiao; Shen, Yueyue [Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Medical Center, New York, NY 10032 (United States); Santella, Regina M. [Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Medical Center, New York, NY 10032 (United States); Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032 (United States)

    2015-09-10

    Long non-coding RNAs (lncRNAs) are larger than 200 nucleotides in length and pervasively expressed across the genome. An increasing number of studies indicate that lncRNA transcripts play integral regulatory roles in cellular growth, division, differentiation and apoptosis. Deregulated lncRNAs have been observed in a variety of human cancers, including hepatocellular carcinoma (HCC). We determined the expression profiles of 90 lncRNAs for 65 paired HCC tumor and adjacent non-tumor tissues, and 55 lncRNAs were expressed in over 90% of samples. Eight lncRNAs were significantly down-regulated in HCC tumor compared to non-tumor tissues (p < 0.05), but no lncRNA achieved statistical significance after Bonferroni correction for multiple comparisons. Within tumor tissues, carrying more aberrant lncRNAs (6–7) was associated with a borderline significant reduction in survival (HR = 8.5, 95% CI: 1.0–72.5). The predictive accuracy depicted by the AUC was 0.93 for HCC survival when using seven deregulated lncRNAs (likelihood ratio test p = 0.001), which was similar to that combining the seven lncRNAs with tumor size and treatment (AUC = 0.96, sensitivity = 87%, specificity = 87%). These data suggest the potential association of deregulated lncRNAs with hepatocarcinogenesis and HCC survival.

  18. Genome-Wide Expression of MicroRNAs Is Regulated by DNA Methylation in Hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Jing Shen

    2015-01-01

    Full Text Available Background. Previous studies, including ours, have examined the regulation of microRNAs (miRNAs by DNA methylation, but whether this regulation occurs at a genome-wide level in hepatocellular carcinoma (HCC is unclear. Subjects/Methods. Using a two-phase study design, we conducted genome-wide screening for DNA methylation and miRNA expression to explore the potential role of methylation alterations in miRNAs regulation. Results. We found that expressions of 25 miRNAs were statistically significantly different between tumor and nontumor tissues and perfectly differentiated HCC tumor from nontumor. Six miRNAs were overexpressed, and 19 were repressed in tumors. Among 133 miRNAs with inverse correlations between methylation and expression, 8 miRNAs (6% showed statistically significant differences in expression between tumor and nontumor tissues. Six miRNAs were validated in 56 additional paired HCC tissues, and significant inverse correlations were observed for miR-125b and miR-199a, which is consistent with the inactive chromatin pattern found in HepG2 cells. Conclusion. These data suggest that the expressions of miR-125b and miR-199a are dramatically regulated by DNA hypermethylation that plays a key role in hepatocarcinogenesis.

  19. Dectin-1 Regulates Hepatic Fibrosis and Hepatocarcinogenesis by Suppressing TLR4 Signaling Pathways.

    Science.gov (United States)

    Seifert, Lena; Deutsch, Michael; Alothman, Sara; Alqunaibit, Dalia; Werba, Gregor; Pansari, Mridul; Pergamo, Matthew; Ochi, Atsuo; Torres-Hernandez, Alejandro; Levie, Elliot; Tippens, Daniel; Greco, Stephanie H; Tiwari, Shaun; Ly, Nancy Ngoc Giao; Eisenthal, Andrew; van Heerden, Eliza; Avanzi, Antonina; Barilla, Rocky; Zambirinis, Constantinos P; Rendon, Mauricio; Daley, Donnele; Pachter, H Leon; Hajdu, Cristina; Miller, George

    2015-12-01

    Dectin-1 is a C-type lectin receptor critical in anti-fungal immunity, but Dectin-1 has not been linked to regulation of sterile inflammation or oncogenesis. We found that Dectin-1 expression is upregulated in hepatic fibrosis and liver cancer. However, Dectin-1 deletion exacerbates liver fibro-inflammatory disease and accelerates hepatocarcinogenesis. Mechanistically, we found that Dectin-1 protects against chronic liver disease by suppressing TLR4 signaling in hepatic inflammatory and stellate cells. Accordingly, Dectin-1(-/-) mice exhibited augmented cytokine production and reduced survival in lipopolysaccharide (LPS)-mediated sepsis, whereas Dectin-1 activation was protective. We showed that Dectin-1 inhibits TLR4 signaling by mitigating TLR4 and CD14 expression, which are regulated by Dectin-1-dependent macrophage colony stimulating factor (M-CSF) expression. Our study suggests that Dectin-1 is an attractive target for experimental therapeutics in hepatic fibrosis and neoplastic transformation. More broadly, our work deciphers critical cross-talk between pattern recognition receptors and implicates a role for Dectin-1 in suppression of sterile inflammation, inflammation-induced oncogenesis, and LPS-mediated sepsis.

  20. Dectin-1 Regulates Hepatic Fibrosis and Hepatocarcinogenesis by Suppressing TLR4 Signaling Pathways

    Directory of Open Access Journals (Sweden)

    Lena Seifert

    2015-12-01

    Full Text Available Dectin-1 is a C-type lectin receptor critical in anti-fungal immunity, but Dectin-1 has not been linked to regulation of sterile inflammation or oncogenesis. We found that Dectin-1 expression is upregulated in hepatic fibrosis and liver cancer. However, Dectin-1 deletion exacerbates liver fibro-inflammatory disease and accelerates hepatocarcinogenesis. Mechanistically, we found that Dectin-1 protects against chronic liver disease by suppressing TLR4 signaling in hepatic inflammatory and stellate cells. Accordingly, Dectin-1–/– mice exhibited augmented cytokine production and reduced survival in lipopolysaccharide (LPS-mediated sepsis, whereas Dectin-1 activation was protective. We showed that Dectin-1 inhibits TLR4 signaling by mitigating TLR4 and CD14 expression, which are regulated by Dectin-1-dependent macrophage colony stimulating factor (M-CSF expression. Our study suggests that Dectin-1 is an attractive target for experimental therapeutics in hepatic fibrosis and neoplastic transformation. More broadly, our work deciphers critical cross-talk between pattern recognition receptors and implicates a role for Dectin-1 in suppression of sterile inflammation, inflammation-induced oncogenesis, and LPS-mediated sepsis.

  1. Platelets promote liver immunopathology contributing to hepatitis B virus-mediated hepatocarcinogenesis.

    Science.gov (United States)

    Sitia, Giovanni

    2014-06-01

    Chronic hepatitis B virus (HBV) infection is a major risk factor for the development of hepatocellular carcinoma (HCC). Among the pathogenetic factors triggered by HBV, virus-specific CD8(+) T cells play and important role in disease pathogenesis by promoting necroinflammatory liver damage. Accordingly, amelioration of immune-mediated chronic liver injury may prevent HCC. Platelets facilitate this process by sustaining the hepatic accumulation of virus-specific CD8(+) T cells and subsequently other virus nonspecific inflammatory cells that contribute to liver disease. Importantly, a recent study shows that the long-term use of clinically relevant doses of the anti-platelet drugs aspirin and clopidogrel, administered after the onset of liver disease, in an HBV transgenic mouse model of immune-mediated chronic hepatitis and HCC, can prevent hepatocarcinogenesis improving overall survival. Platelets therefore, act as key players in the pathogenesis of HBV-associated liver cancer supporting the notion that immune-mediated necroinflammatory liver disease is sufficient to trigger HCC and that interference with platelet activation may have clinical implications for HCC prevention.

  2. Inhibition of early 3-methyl-4-dimethylaminoazobenzene-induced hepatocarcinogenesis by gomisin A in rats.

    Science.gov (United States)

    Nomura, M; Ohtaki, Y; Hida, T; Aizawa, T; Wakita, H; Miyamoto, K

    1994-01-01

    The effects of gomisin A, a lignan component of Schizandra fruits, on hepatocarcinogenesis caused by 3'-methyl-4- dimethylaminoazobenzene (3'-MeDAB) in male Donryu rats were investigated. Gomisin A significantly inhibited the appearance of foci stained for glutathione S-transferase placental form (GST-P) in the liver of rats given feed with 0.06% 3'-MeDAB. Gomisin A (30 mg/kg/daily, po) decreased the concentration of 3'-MeDAB-related azo dyes in the liver, and increased their excretion in the bile. The ratio of diploid to tetraploid nuclei increased during ingestion of 3'-MeDAB, but gomisin A delayed the increase. After the withdrawal of 3'-MeDAB, carcinogen-related azo dyes were not detected in the liver or bile, but the proportion of diploid nuclei remained high, although it decreased with a 0.03% gomisin A diet. The results suggested that the effects of gomisin A are related to improved liver function and reversal of abnormal ploidization.

  3. Heat Shock Response Associated with Hepatocarcinogenesis in a Murine Model of Hereditary Tyrosinemia Type I

    Directory of Open Access Journals (Sweden)

    Francesca Angileri

    2014-04-01

    Full Text Available Hereditary Tyrosinemia type 1 (HT1 is a metabolic liver disease caused by genetic defects of fumarylacetoacetate hydrolase (FAH, an enzyme necessary to complete the breakdown of tyrosine. The severe hepatic dysfunction caused by the lack of this enzyme is prevented by the therapeutic use of NTBC (2-[2-nitro-4-(trifluoromethylbenzoyl] cyclohexane-1,3-dione. However despite the treatment, chronic hepatopathy and development of hepatocellular carcinoma (HCC are still observed in some HT1 patients. Growing evidence show the important role of heat shock proteins (HSPs in many cellular processes and their involvement in pathological diseases including cancer. Their survival-promoting effect by modulation of the apoptotic machinery is often correlated with poor prognosis and resistance to therapy in a number of cancers. Here, we sought to gain insight into the pathophysiological mechanisms associated with liver dysfunction and tumor development in a murine model of HT1. Differential gene expression patterns in livers of mice under HT1 stress, induced by drug retrieval, have shown deregulation of stress and cell death resistance genes. Among them, genes coding for HSPB and HSPA members, and for anti-apoptotic BCL-2 related mitochondrial proteins were associated with the hepatocarcinogenetic process. Our data highlight the variation of stress pathways related to HT1 hepatocarcinogenesis suggesting the role of HSPs in rendering tyrosinemia-affected liver susceptible to the development of HCC.

  4. Heat Shock Response Associated with Hepatocarcinogenesis in a Murine Model of Hereditary Tyrosinemia Type I

    Energy Technology Data Exchange (ETDEWEB)

    Angileri, Francesca; Morrow, Geneviève; Roy, Vincent; Orejuela, Diana; Tanguay, Robert M., E-mail: robert.tanguay@ibis.ulaval.ca [Laboratory of Cell and Developmental Genetics, Department of Molecular Biology, Medical Biochemistry and Pathology, Institut de Biologie Intégrative et des Systèmes (IBIS) and PROTEO, 1030 avenue de la médecine, Université Laval, Québec G1V 0A6 (Canada)

    2014-04-23

    Hereditary Tyrosinemia type 1 (HT1) is a metabolic liver disease caused by genetic defects of fumarylacetoacetate hydrolase (FAH), an enzyme necessary to complete the breakdown of tyrosine. The severe hepatic dysfunction caused by the lack of this enzyme is prevented by the therapeutic use of NTBC (2-[2-nitro-4-(trifluoromethyl)benzoyl]cyclohexane-1,3-dione). However despite the treatment, chronic hepatopathy and development of hepatocellular carcinoma (HCC) are still observed in some HT1 patients. Growing evidence show the important role of heat shock proteins (HSPs) in many cellular processes and their involvement in pathological diseases including cancer. Their survival-promoting effect by modulation of the apoptotic machinery is often correlated with poor prognosis and resistance to therapy in a number of cancers. Here, we sought to gain insight into the pathophysiological mechanisms associated with liver dysfunction and tumor development in a murine model of HT1. Differential gene expression patterns in livers of mice under HT1 stress, induced by drug retrieval, have shown deregulation of stress and cell death resistance genes. Among them, genes coding for HSPB and HSPA members, and for anti-apoptotic BCL-2 related mitochondrial proteins were associated with the hepatocarcinogenetic process. Our data highlight the variation of stress pathways related to HT1 hepatocarcinogenesis suggesting the role of HSPs in rendering tyrosinemia-affected liver susceptible to the development of HCC.

  5. Dose response for TCDD promotion of hepatocarcinogenesis in rats initiated with DEN: histologic, biochemical, and cell proliferation endpoints.

    OpenAIRE

    Maronpot, R R; Foley, J F; Takahashi, K; Goldsworthy, T; Clark, G; Tritscher, A; Portier, C; Lucier, G

    1993-01-01

    The present study examines the dose-response relationship for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) promotion of histologic and biochemical parameters by using a two-stage model for hepatocarcinogenesis in female Sprague-Dawley rats initiated with a single intraperitoneal dose of 175 mg of diethylnitrosamine (DEN)/kg body weight at 70 days of age. Starting 2 weeks after initiation, treatment groups of 8-10 rats were given TCDD by gavage in corn oil once every 2 weeks for 30 weeks. Doses ...

  6. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  7. Hepatic gene expression profiles associated with fibrosis progression and hepatocarcinogenesis in hepatitis C patients

    Institute of Scientific and Technical Information of China (English)

    Run-Xuan Shao; Takao Kawabe; Masao Omata; Yujin Hoshida; Motoyuki Otsuka; Naoya Kato; Ryosuke Tateishi; Takuma Teratani; Shuichiro Shiina; Hiroyoshi Taniguchi; Masaru Moriyama

    2005-01-01

    AIM: To determine fibrosis progression and hepatocellular carcinoma (HCC), using simultaneous gene expression analysis.METHODS: Total RNA samples were extracted from liver biopsies from 19 patients with hepatitis C virus (HCV)infection and 3 patients without HCV infection. Among the 19 HCV-infected patients, 7 and 12 patients had grade F1-2 and F3-4 fibrosis, respectively. Of the 12 patients with F3-4 fibrosis, 8 had HCC. Gene expression in the liver samples was determined using an oligonucleotide microarray. The following comparisons were performed:normal livers vs HCV-infected livers; F1-2 vs F3-4; and F3-4 with HCC vs F3-4 without HCC. Genes that were differentially expressed between these groups were identified based on signal-to-noise ratios.RESULTS: In the HCV-infected livers, genes involved in immune responses were highly expressed. Expression levels of genes for plasma proteins and drug-metabolizing enzymes were decreased and those of genes involved in the cell cycle and oncogenesis were increased in the F3-4 cases as compared to the F1-2 cases. Among the F3-4 cases, genes involved in carbohydrate metabolism tended to be more highly expressed in patients with HCC than in patients without HCC.CONCLUSION: We identified genes that are associated with fibrosis progression and hepatocarcinogenesis. This information may be used to detect increased carcinogenic potential in the livers of patients with HCV infection.

  8. Potential chemoprevention of diethylnitrosamine-induced hepatocarcinogenesis in rats: myrrh (Commiphora molmol) vs. turmeric (Curcuma longa).

    Science.gov (United States)

    El-Shahat, Mohamed; El-Abd, Sabah; Alkafafy, Mohamed; El-Khatib, Gamal

    2012-09-01

    The aim of the present study was to assess the potential chemopreventive effects of myrrh (Commiphora molmol) vs. turmeric (Curcuma longa) in hepatocarcinogenic rats induced by a single intraperitoneal injection of diethylnitrosamine (DENA) (200 mg/kg body weight). Ninety male Wistar rats used in this study were randomly divided into six equal groups (n=15). Group 1 rats served as negative controls; group 2 received a single i.p. injection of DENA and served as positive controls. Rats in both groups were fed on basal diet. Group 3 rats were fed a diet containing 5% turmeric, whereas group 4 rats were fed a diet containing 2% myrrh. Rats in groups 5 and 6 received a single i.p. injection of DENA and were fed diets containing 5% turmeric and 2% myrrh, respectively. The study demonstrated that DENA caused a significant increase in serum indices of liver enzymes and also severe histological and immunohistochemical changes in hepatic tissues. These included disorganized hepatic parenchyma, appearance of pseudoacinar and trabecular arrays of hepatocytes and alterations in CD10-immunoreactivity. Dietary supplementation of turmeric relatively improved the biochemical parameters to values approximating those of the negative controls and delayed the initiation of carcinogenesis. In contrast, myrrh did not improve the biochemical parameters or delay the hepatocarcinogenesis. Both turmeric and myrrh induced significant biochemical and histological changes in non-treated rats. In conclusion, DENA significantly changes the biological enzymatic activities in serum and the integrity of hepatic tissues. Phytochemicals with potential hepatoprotective effects must be applied cautiously owing to their potential hepatotoxicity.

  9. The uptake transporter OATP8 expression decreases during multistep hepatocarcinogenesis: correlation with gadoxetic acid enhanced MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kitao, Azusa; Matsui, Osamu; Yoneda, Norihide; Kozaka, Kazuto; Shinmura, Rieko; Koda, Wataru; Kobayashi, Satoshi; Gabata, Toshifumi [Kanazawa University Graduate School of Medical Science, Department of Radiology, Kanazawa (Japan); Zen, Yoh [Kanazawa University Graduate School of Medical Science, Human Pathology, Kanazawa (Japan); King' s College Hospital, Institute of Liver Studies, London (United Kingdom); Yamashita, Tatsuya; Kaneko, Shuichi [Kanazawa University Graduate School of Medical Science, Gastroenterology, Kanazawa (Japan); Nakanuma, Yasuni [Kanazawa University Graduate School of Medical Science, Human Pathology, Kanazawa (Japan)

    2011-10-15

    To clarify the changes in organic anion-transporting polypeptide 8 (OATP8) expression and enhancement ratio on gadoxetic acid-enhanced MR imaging in hepatocellular nodules during multistep hepatocarcinogenesis. In imaging analysis, we focused on 71 surgically resected hepatocellular carcinomas (well, moderately and poorly differentiated HCCs) and 1 dysplastic nodule (DN). We examined the enhancement ratio in the hepatobiliary phase of gadoxetic acid enhanced MR imaging [(1/postcontrast T1 value-1/precontrast T1 value)/(1/precontrast T1 value)], then analysed the correlation among the enhancement ratio, tumour differentiation grade and intensity of immunohistochemical OATP8 expression. In pathological analysis, we focused on surgically resected 190 hepatocellular nodules: low-grade DNs, high-grade DNs, early HCCs, well-differentiated, moderately differentiated and poorly differentiated HCCs, including cases without gadoxetic acid-enhanced MR imaging. We evaluated the correlation between the immunohistochemical OATP8 expression and the tumour differentiation grade. The enhancement ratio of HCCs decreased in accordance with the decline in tumour differentiation (P < 0.0001, R = 0.28) and with the decline of OATP8 expression (P < 0.0001, R = 0.81). The immunohistochemical OATP8 expression decreased from low-grade DNs to poorly differentiated HCCs (P < 0.0001, R = 0.15). The immunohistochemical expression of OATP8 significantly decreases during multistep hepatocarcinogenesis, which may explain the decrease in enhancement ratio on gadoxetic acid-enhanced MR imaging. (orig.)

  10. Orally administered lycopene attenuates diethylnitrosamine-induced hepatocarcinogenesis in rats by modulating Nrf-2/HO-1 and Akt/mTOR pathways.

    Science.gov (United States)

    Sahin, Kazim; Orhan, Cemal; Tuzcu, Mehmet; Sahin, Nurhan; Ali, Shakir; Bahcecioglu, Ibrahim H; Guler, Osman; Ozercan, Ibrahim; Ilhan, Necip; Kucuk, Omer

    2014-01-01

    Hepatocarcinogenesis is one of the most prevalent and lethal cancers. We studied the mechanisms underlying the inhibition of diethylnitrosamine (DEN)-induced hepatocarcinogenesis by lycopene in rats. Hepatocarcinogenesis was induced by an intraperitoneal injection of DEN followed by promotion with phenobarbital for 24 successive wk. The rats were given lycopene (20 mg/kg body weight) 3 times a week orally for 4 wk prior to initiation, and the treatment was continued for 24 consecutive wk. Lycopene reduced incidence, number, size, and volume of hepatic nodules. Serum alanine transaminase, aspartate aminotransferase, total bilirubin, and malondialdehyde (MDA) considerably increased and hepatic antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase) and glutathione decreased in DEN-treated rats when compared with the control group. Lycopene significantly reversed these biochemical changes and increased the expression of NF-E-2-related factor-2)/heme oxygenase-1, and it decreased NF-κB/cyclooxygenase-2, inhibiting the inflammatory cascade and activating antioxidant signaling (P B (P < 0.05). Lycopene is an active chemopreventive agent that offers protection against DEN-induced hepatocarcinogenesis by inhibiting NF-κB and mTOR pathways.

  11. Comparison of different LED Packages

    Science.gov (United States)

    Dieker, Henning; Miesner, Christian; Püttjer, Dirk; Bachl, Bernhard

    2007-09-01

    In this paper different technologies for LED packaging are compared, focusing on Chip on Board (COB) and SMD technology. The package technology which is used depends on the LED application. A critical fact in LED technology is the thermal management, especially for high brightness LED applications because the thermal management is important for reliability, lifetime and electrooptical performance of the LED module. To design certain and long life LED applications knowledge of the heat flow from LEDs to the complete application is required. High sophisticated FEM simulations are indispensable for modern development of high power LED applications. We compare simulations of various substrate materials and packaging technologies simulated using FLOTHERM software. Thereby different substrates such as standard FR4, ceramic and metal core printed circuit boards are considered. For the verification of the simulated results and the testing of manufactured modules, advanced measurement tools are required. We show different ways to experimentally characterize the thermal behavior of LED modules. The thermal path is determined by the transient thermal analysis using the MicReD T3Ster analyzer. Afterwards it will be compared to the conventional method using thermocouples. The heat distribution over the module is investigated by an IR-Camera. We demonstrate and compare simulation and measurement results of Chip-on-Board (COB) and Sub-Mounted Devices (SMD) technology. The results reveal that for different applications certain packages are ideal.

  12. New Phosphors for White LEDs

    Institute of Scientific and Technical Information of China (English)

    LIU Ru-Shi

    2004-01-01

    White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or UV LEDs) and photoluminescence phosphors. GaN-based highly efficient blue InGaN LEDs combined with phosphors can produce white light. These solid-state LED lamps have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability, and long operating lifetime (about 100,000 hours). For the purpose of development of high energy-efficient white light sources, we need to produce highly efficient new phosphors, which can absorb excitation energy from blue or UV LEDs and generate emissions.In this paper, we investigate the development of blue or UV LEDs by the appropriate combination of new phosphors which can lead us to obtain high brightness white light. The criteria of choosing the best phosphors, for blue (380-450 nm) and UV (360-400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance light between the light emission from blue LEDs and the yellow YAG:Ce,Gd phosphor is important to obtain white light with high color temperature. The phosphors with high efficiency which can be excited by UV LEDs are important to obtain the white light with high color rendering index.

  13. Altered expression of cytochrome P450 and possible correlation with preneoplastic changes in early stage of rat hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Lin-lin LIU; Li-kun GONG; Xin-ming QI; Yan CAI; Hui WANG; Xiong-fei WU; Ying XIAO; Jin REN

    2005-01-01

    Aim: Correlation of cytochrome P450 (CYPs) with preneoplastic changes in the early stage of hepatocarcinogenesis is still unclear. To detect the expression of carcinogen-metabolizing related microsomal P450 enzymes, namely the CYP1A1,CYP1A2, CYP2B 1/2, CYP2E1, and CYP3A, we performed the medium-term bioassay of Ito's model in Sprague-Dawley rats. Methods: The amount and activity of CYP were assessed by biochemical and immunohistochemical methods in week 8.The correlation between CYP expression and microsomal oxidative stress was investigated by comparing the generation of microsomal lipid peroxidation in the presence or absence of specific CYP inhibitor. Results: In the DEN-2-AAF and 2-AAF alone groups, the expression of CYP1A1 and CYP2E1 were up-regulated and the expression of CYP2B 1/2 and CYP1A2 were quite the contrary. Strong staining of CYP2E1 and CYP2B1/2 was found around the centrolobular vein and weak staining in the altered hepatic foci revealed by immunohistochemical procedure.There was no significant change in the activity of CYP3A among the 4 groups.Altered hepatic tissue bore more microsomal NADPH (nicotinamide adenine dimucleotide phosphate,reduced form)-dependent lipid peroxidation than normal tissue. And the difference among the 4 groups disappeared when CYP2E1 was inhibited. More microsomal lipid peroxidation was generated when incubated with CYP1A inhibitor α-naphthoflavone. Conclusion: CYP altered their expression levels and these alterations can play important roles in the alteration of cell redox status of preneoplastic tissue in the early stage of hepatocarcinogenesis.

  14. Deoxycholic acid as an endogenous risk factor for hepatocarcinogenesis and effects of gomisin A, a lignan component of Schizandra fruits.

    Science.gov (United States)

    Ohtaki, Y; Hida, T; Hiramatsu, K; Kanitani, M; Ohshima, T; Nomura, M; Wakita, H; Aburada, M; Miyamoto, K I

    1996-01-01

    Although hepatocarcinogensis has been reported to be promoted by exogenous administration of bile acids, the relation of endogenous bile acids to hepatocarcinogenesis is not completely understood. This study investigates the relationship between serum concentration of bile acids, the appearance of preneoplastic change, glutathione S-transferase placental form (GST-P)-positive foci in the liver of male Donryu rats which had been fed 0.06% 3'-methyl-4-dimethylamino-azobenzene (3'-MeDAB), and the effects of gomisin A, previously reported to inhibit the tumor promotion process. During the feeding of 3'-MeDAB for 5 weeks, the concentrations of serum bile acids were found to have increased significantly to several times the levels found at the start of the experiment. The increase of serum bile acids, especially deoxycholic acid (DCA), and the appearance of preneoplastic lesions, the number and area of GST-P-positive foci in the liver, were significantly inhibited by simultaneous oral administration of gomisin A (30 mg/kg). When DCA (100 mg/kg) was orally administered after an initiation by 3'-MeDAB, serum bile acids and preneoplastic changes were significantly increased, these increases were inhibited by combined feeding of 0.03% gomisin A in the diet. There were good correlations between the serum concentration of DCA and the number of GST-P-positive foci in the liver in both experimental protocols. These results confirm that DCA is an endogenous risk factor for hepatocarcinogenesis and suggest that anti-promoter effect of gomisin A is based on improving metabolism of bile acids, including DCA.

  15. TGFbeta-mediated upregulation of hepatic miR-181b promotes hepatocarcinogenesis by targeting TIMP3.

    Science.gov (United States)

    Wang, B; Hsu, S-H; Majumder, S; Kutay, H; Huang, W; Jacob, S T; Ghoshal, K

    2010-03-25

    To identify microRNAs (miRNAs) that may have a causal role in hepatocarcinogenesis, we used an animal model in which C57BL/6 mice fed choline-deficient and amino acid defined (CDAA) diet develop preneoplastic lesions at 65 weeks and hepatocellular carcinomas after 84 weeks. miRNA expression profiling showed significant upregulation of miR-181b and miR-181d in the livers of mice as early as 32 weeks that persisted at preneoplastic stage. The expression of tissue inhibitor of metalloprotease 3 (TIMP3), a tumor suppressor and a validated miR-181 target, was markedly suppressed in the livers of mice fed CDAA diet. Upregulation of hepatic transforming growth factor (TGF)beta and its downstream mediators Smad 2, 3 and 4 and increase in phospho-Smad2 in the liver nuclear extract correlated with elevated miR-181b/d in mice fed CDAA diet. The levels of the precursor and mature miR-181b were augmented on exposure of hepatic cells to TGFbeta and were significantly reduced by small interference RNA-mediated depletion of Smad4, showing the involvement of TGFbeta signaling pathway in miR-181b expression. Ectopic expression and depletion of miR-181b showed that miR-181b enhanced matrix metallopeptidases (MMP)2 and MMP9 activity and promoted growth, clonogenic survival, migration and invasion of hepatocellular carcinoma (HCC) cells that could be reversed by modulating TIMP3 level. Further, depletion of miR-181b inhibited tumor growth of HCC cells in nude mice. miR-181b also enhanced resistance of HCC cells to the anticancer drug doxorubicin. On the basis of these results, we conclude that upregulation of miR-181b at early stages of feeding CDAA diet promotes hepatocarcinogenesis.

  16. Phosphors and PDP, LED Technology

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Phosphors for PDP has good prospect for the largepotential of PDP industry. LED technology brings new marketto be developed. Developing phosphors for white LED withhigh efficiency and low light attenuation is an urgent work todo. Application of phosphors in color LED is in initial stage.1. Good Prospect of Phosphors for PDPColor PDP is widely used today. Three-prime-colorphosphor excited by VUV is the key material for color PDP.This makes research on three-prime-color phosphor for colorPDP important. Follow...

  17. LED minilidar for Mars rover

    Science.gov (United States)

    Shiina, Tatsuo; Yamada, Sonoko; Senshu, Hiroki; Otobe, Naohito; Hashimoto, George; Kawabata, Yasuhiro

    2016-10-01

    A mini-lidar to observe the activity of Martian atmosphere is developed. The 10cm-cube LED mini-lidar was designed to be onboard a Mars rover. The light source of the mini-lidar is a high powered LED of 385nm. LED was adopted as light source because of its toughness against circumference change and physical shock for launch. The pulsed power and the pulse repetition frequency of LED beam were designed as 0.75W (=7.5nJ/10ns) and 500kHz, respectively. Lidar echoes were caught by the specially designed Cassegrain telescope, which has the shorter telescope tube than the usual to meet the 10cm-cube size limit. The high-speed photon counter was developed to pursue to the pulse repetition frequency of the LED light. The measurement range is no shorter than 30m depending back-ground condition. Its spatial resolution was improved as 0.15m (=1ns) by this photon counter. The demonstrative experiment was conducted at large wind tunnel facility of Japan Meteorological Agency. The measurement target was smoke of glycerin particles. The smoke was flowed in the wind tunnel with wind speed of 0 - 5m. Smoke diffusion and its propagation due to the wind flow were observed by the LED mini-lidar. This result suggests that the developed lidar can pursue the structure and the motion of dust devil of >2m.

  18. Impurity Influence on Nitride LEDs

    Directory of Open Access Journals (Sweden)

    O.I. Rabinovich

    2014-07-01

    Full Text Available Light emitting diodes (LEDs are widely used nowadays. They are used in major parts of our life. But it is still necessary to improve their characteristics. In this paper the impurity and Indium atoms influence on the LEDs characteristics is investigated by computer simulation. Simulation was carried out in Sim Windows. The program was improved for this purpose by creating new files for AlGaInN heterostructure and devices including more than 25 basic parameters. It was found that characteristics depend on impurity and indium atoms changes a lot. The optimum impurity concentration for doping barriers between quantum wells was achieved. By varying impurity and Indium concentration the distribution in AlGaInN heterostructure LEDs characteristics could be improved.

  19. Semiconductor lasers and herterojunction leds

    CERN Document Server

    Kressel, Henry

    2012-01-01

    Semiconductor Lasers and Heterojunction LEDs presents an introduction to the subject of semiconductor lasers and heterojunction LEDs. The book reviews relevant basic solid-state and electromagnetic principles; the relevant concepts in solid state physics; and the p-n junctions and heterojunctions. The text also describes stimulated emission and gain; the relevant concepts in electromagnetic field theory; and the modes in laser structures. The relation between electrical and optical properties of laser diodes; epitaxial technology; binary III-V compounds; and diode fabrication are also consider

  20. Multicolor, High Efficiency, Nanotextured LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Jung Han; Arto Nurmikko

    2011-09-30

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and green for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) heteroepitaxy of nitrogen-polar LEDs on sapphire, (ii) heteroepitaxy of semipolar (11{bar 2}2) green LEDs on sapphire, (iii) synthesis of quantum-dot loaded nanoporous GaN that emits white light without phosphor conversion, (iv) demonstration of the highest quality semipolar (11{bar 2}2) GaN on sapphire using orientation-controlled epitaxy, (v) synthesis of nanoscale GaN and InGaN medium, and (vi) development of a novel liftoff process for manufacturing GaN thin-film vertical LEDs. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  1. New Processing of LED Phosphors

    OpenAIRE

    Toda, Kenji

    2012-01-01

    In order to synthesize LED phosphor materials, we have applied three novel synthesis techniques, “melt synthesis”, “fluidized bed synthesis” and “vapor-solid hybrid synthesis”, in contrast with the conventional solid state reaction technique. These synthesis techniques are also a general and powerful tool for rapid screening and improvements of new phosphor materials.

  2. Effects of Ginkgo biloba extract on expression of biomarkers during aflatoxin B1-induced hepatocarcinogenesis in Wistar rats

    Institute of Scientific and Technical Information of China (English)

    Yanrong Hao; Jianjia Su; Chao Ou; Ji Cao; Fang Yang; Xiaoxian Duan; Chun Yang; Yuan Li

    2012-01-01

    Objective: The aim of this study was to study the effect of Ginkgo biloba extract (EGb761) on metabolism of aflatoxin B1 (AFB1) in Wistar rats. Methods: Seventy one Wistar rats were assigned at random to groups A, B and C. Rats in groups A, B were injected with AFB1 (intraperitoneal, 100–200 μg/kg body weight, 1–3 times/week). Group C was normal control. Rats in group B were fed in food with EGb761, while rats in groups A, C were given normal food. Blood samples were collected and liver biopsies were performed on the 14th, 28th and 42nd week. All the rats were sacrificed on the 64th week. The incidence of hepatocarcinoma was investigated. The hepatic phase I drug-metabolizing enzyme Cytochrome-P450 (CYP450) and phase II metabolizing enzyme glutathione S-transferase (GST) were analyzed with spectrometry. Serum AFB1-lysine adduct levels were assessed with high performance liquid chromatography (HPLC). The expression of 8-hydroxydeoxy-guanosine (8-OHdG) was measured with immunohistochemistry. Results: The incidence of hepatocellular carcinoma (HCC) in group B was significantly lower than that in group A (26.92% vs 76.00%, P < 0.001). No HCC developed in group C. EGb761 showed no effects on the activities of CYP450 and GST in rat liver tissues. The level of AFB1-lysine adduct reached the peak (4356.01 pg/mg albumin) at the 14th week in group A. EGb761 significantly inhibited the formation of AFB1-lysine adduct in serum by 13.07% at the 14th week (P = 0.033), and 73.63% at the 42nd week (P = 0.002). The expression of 8-OHdG protein in rat liver tissues in group B was significantly lower than that in group A at the 28th, 42nd, and 64th week (P < 0.05). Conclu-sion: The main mechanism underlying the effect of EGb761 in blocking hepatocarcinogenesis induced by AFB1 may not be fully attributable to its influence on the activity of liver phase I and phase II metabolizing enzymes. EGb761 inhibits the produc-tion of AFB1-lysine adducts, decreases the expression of 8-OHd

  3. LED lamp color control system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A.M.

    2013-02-05

    An LED lamp color control system and method including an LED lamp having an LED controller 58; and a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 determines whether the LED source 80 is in a feedback controllable range, stores measured optical flux for the LED source 80 when the LED source 80 is in the feedback controllable range, and bypasses storing the measured optical flux when the LED source 80 is not in the feedback controllable range.

  4. LED lamp power management system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A. M.

    2013-03-19

    An LED lamp power management system and method including an LED lamp having an LED controller 58; a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 reduces power loss in one of the channel switch 62 and the shunt switch 68 when LED lamp electronics power loss (P.sub.loss) exceeds an LED lamp electronics power loss limit (P.sub.lim); and each of the channel switches 62 receives a channel switch control signal 63 from the LED controller 58 and each of the shunt switches 68 receives a shunt switch control signal 69 from the LED controller 58.

  5. Radiometry of flashing LED sources

    Science.gov (United States)

    Gregory, Don A.; Medley, Stephanie; Roberts, Adam

    2008-08-01

    A laboratory based technique has been devised for measuring the illumination characteristics of flashing light emitting diode (LED) sources. The difference between the photopic measurement of a continuous source and a flashing source is that some analytic method must be incorporated into the measurement to account for the response of the eye. Ohno et al have devised an analytic expression for the impulse response of the eye, which closely matches existing forms used for finding effective intensity1. These other forms are the Blondel-Rey equation, the Form Factor method, and the Allard method.4,5,6 Ohno's research suggests a modified Allard method, but offers no procedure for actually making the measurement. In this research, the modified Allard1 method approach has been updated using standard laboratory equipment such as a silicon detector in conjunction with a digital multi-meter and Labview® software to make this measurement. Labview® allows exact computation of the modified Allard method. However, an approximation scheme for the conversion from radiometric units to photopic units must be adopted. The LED spectral form is approximately a Gaussian line shape with full width at half maximum of about 15 to 30nm. The Gaussian curve makes converting from radiometric to photopic units difficult. To simplify, the technique presented here estimates the spectral form of the LEDs to be a Dirac delta function situated at the peak wavelength. This allows the conversion from watts to lumens to be a simple application of the luminous efficiency curve.2 For LEDs with a full width half maximum of 20nm, this scheme is found to be accurate to +/- 5%.

  6. Characteristics of hepatic nuclear-transcription factor-kappa B expression and quantitative analysis in rat hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Wei Wu; Wen-Jing Gu; Deng-Fu Yao; Li-Wei Qiu; Wen-Li Sai; Jun-Jun Shen; Hong-Bo Yu; Xin-Hua Wu; Yue-Ming Li; Yi-Lang Wang

    2009-01-01

    BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. We analyzed the expression of nuclear-transcription factor-kappa B (NF-κB) during hepatocarcinogenesis in order to evaluate its dynamic expression and its clinical value in the development and diagnosis of HCC. METHODS: Hepatoma models were induced by oral administration of 2-acetamidoflurene (2-FAA) to male Sprague-Dawley rats. Morphological changes were observed afterhematoxylinandeosinstaining.Thecellulardistribution of NF-κB expression during different stages of cancer development was investigated by immunohistochemistry, and the level of NF-κB expression in liver tissues was quantitatively analyzed by ELISA. The gene fragments of hepatic NF-κB were amplified by nested-polymerase chain reaction assay. RESULTS: Hepatocytes showed vacuole-like degeneration during the early stages, then had a hyperplastic nodal appearance during the middle stages, and finally progressed to tubercles of cancerous nests with high differentiation. The NF-κB-positive material was buff-colored, fine particles localized in the nucleus, and the incidence of NF-κB-positive cells was 81.8% in degeneration, 83.3% in precancerous lesions, and 100% in cancerous tissues. All of these values were higher than those in controls (P CONCLUSION: The NF-κB signal transduction pathway is activated during the early stages of HCC development, and its abnormal expression may be associated with the occurrence of HCC.

  7. RIP3 Inhibits Inflammatory Hepatocarcinogenesis but Promotes Cholestasis by Controlling Caspase-8- and JNK-Dependent Compensatory Cell Proliferation

    Directory of Open Access Journals (Sweden)

    Mihael Vucur

    2013-08-01

    Full Text Available For years, the term “apoptosis” was used synonymously with programmed cell death. However, it was recently discovered that receptor interacting protein 3 (RIP3-dependent “necroptosis” represents an alternative programmed cell death pathway activated in many inflamed tissues. Here, we show in a genetic model of chronic hepatic inflammation that activation of RIP3 limits immune responses and compensatory proliferation of liver parenchymal cells (LPC by inhibiting Caspase-8-dependent activation of Jun-(N-terminal kinase in LPC and nonparenchymal liver cells. In this way, RIP3 inhibits intrahepatic tumor growth and impedes the Caspase-8-dependent establishment of specific chromosomal aberrations that mediate resistance to tumor-necrosis-factor-induced apoptosis and underlie hepatocarcinogenesis. Moreover, RIP3 promotes the development of jaundice and cholestasis, because its activation suppresses compensatory proliferation of cholangiocytes and hepatic stem cells. These findings demonstrate a function of RIP3 in regulating carcinogenesis and cholestasis. Controlling RIP3 or Caspase-8 might represent a chemopreventive or therapeutic strategy against hepatocellular carcinoma and biliary disease.

  8. Water extracts of cabbage and kale inhibit ex vivo H(2)O(2)-induced DNA damage but not rat hepatocarcinogenesis.

    Science.gov (United States)

    Horst, M A; Ong, T P; Jordão, A A; Vannucchi, H; Moreno, F S; Lajolo, F M

    2010-03-01

    The chemopreventive potential of water extracts of the Brassica vegetables cabbage and kale was evaluated by administering their aqueous extracts in drinking water ad libitum to Wistar rats submitted to Ito's hepatocarcinogenesis model (CB group and K group, respectively - 14 rats per group). Animals submitted to this same model and treated with water were used as controls (W group - 15 rats). Treatment with the vegetable extracts did not inhibit (P > 0.05) placental glutathione S-transferase-positive preneoplastic lesions (PNL). The number of apoptotic bodies did not differ (P > 0.05) among the experimental groups. Ex vivo hydrogen peroxide treatment of rat livers resulted in lower (P kale- (110.8 +/- 10.0 microm) treated animals compared with control (120.9 +/- 12.7 microm), as evaluated by the single cell gel (comet) assay. Treatment with cabbage (2 +/- 0.3 microg/g) or kale (4 +/- 0.2 microg/g) resulted in increased (P kale aqueous extracts on PNL, these Brassica vegetables presented protection against DNA damage, an effect possibly related to increased hepatic lutein concentrations. However, it must be pointed out that the cause-effect relationship between lutein levels and protection is hypothetical and remains to be demonstrated.

  9. Low Cost Heart Rate Monitor Using Led-Led Sensor

    Directory of Open Access Journals (Sweden)

    Ahmed Mahrous Ragib

    2009-01-01

    Full Text Available A high sensitivity, low power and low cost sensor has been developed for photoplethysmography (PPG measurement. The PPG principle was applied to follow the dilatation and contraction of skin blood vessels during the cardiac cycle. A standard light emitting diodes (LEDs has been used as a light emitter and detector, and in order to reduce the space, cost and power, the classical analogue-to-digital converters (ADCs replaced by the pulse-based signal conversion techniques. A general purpose microcontroller has been used for the implementation of measurement protocol. The proposed approach leads to better spectral sensitivity, increased resolution, reduction in cost, dimensions and power consumption. The basic sensing configuration presented is capable of detecting the PPG signal from a finger or toe, and it is very simple to extract the heart rate and heart rate variability from such a signal.

  10. Overexpression of a splice variant of DNA methyltransferase 3b, DNMT3b4, associated with DNA hypomethylation on pericentromeric satellite regions during human hepatocarcinogenesis.

    Science.gov (United States)

    Saito, Yoshimasa; Kanai, Yae; Sakamoto, Michiie; Saito, Hidetsugu; Ishii, Hiromasa; Hirohashi, Setsuo

    2002-07-23

    DNA hypomethylation on pericentromeric satellite regions is an early and frequent event associated with heterochromatin instability during human hepatocarcinogenesis. A DNA methyltransferase, DNMT3b, is required for methylation on pericentromeric satellite regions during mouse development. To clarify the molecular mechanism underlying DNA hypomethylation on pericentromeric satellite regions during human hepatocarcinogenesis, we examined mutations of the DNMT3b gene and mRNA expression levels of splice variants of DNMT3b in noncancerous liver tissues showing chronic hepatitis and cirrhosis, which are considered to be precancerous conditions, and in hepatocellular carcinomas (HCCs). Mutation of the DNMT3b gene was not found in HCCs. Overexpression of DNMT3b4, a splice variant of DNMT3b lacking conserved methyltransferase motifs IX and X, significantly correlated with DNA hypomethylation on pericentromeric satellite regions in precancerous conditions and HCCs (P = 0.0001). In particular, the ratio of expression of DNMT3b4 to that of DNMT3b3, which is the major splice variant in normal liver tissues and retains conserved methyltransferase motifs I, IV, VI, IX, and X, showed significant correlation with DNA hypomethylation (P = 0.009). Transfection of human epithelial 293 cells with DNMT3b4 cDNA induced DNA demethylation on satellite 2 in pericentromeric heterochromatin DNA. These results suggest that overexpression of DNMT3b4, which may lack DNA methyltransferase activity and compete with DNMT3b3 for targeting to pericentromeric satellite regions, results in DNA hypomethylation on these regions, even in precancerous stages, and plays a critical role in human hepatocarcinogenesis by inducing chromosomal instability.

  11. Identification of c-Yes expression in the nuclei of hepatocellular carcinoma cells: involvement in the early stages of hepatocarcinogenesis.

    Science.gov (United States)

    Nonomura, Takako; Masaki, Tsutomu; Morishita, Asahiro; Jian, Gong; Uchida, Naohito; Himoto, Takashi; Izuishi, Kunihiko; Iwama, Hisakazu; Yoshiji, Hitoshi; Watanabe, Seishiro; Kurokohchi, Kazutaka; Kuriyama, Shigeki

    2007-01-01

    It is thought that the subcellular distribution of Src-family tyrosine kinases, including c-Yes binding to the cellular membrane, is membranous and/or cytoplasmic. c-Yes protein tyrosine kinase is known to be related to malignant transformation. However, the expression patterns of c-Yes in hepatocellular carcinoma (HCC) remains unknown. In the present study, we report that c-Yes is expressed not only in the membrane and cytoplasm, but also in the nuclei of cancer cells in some human HCC tissues and in a human HCC cell line. We examined the expression and localization of c-Yes in human HCC cell lines (HLE, HLF, PLC/PRF/5 and Hep 3B) by Western blotting and immunohistochemical analyses; we also examined the expression of c-Yes by immunohistochemistry and Western blotting in the tissues of various liver diseases, including 39 samples from HCC patients. We used an antibody array to detect proteins that bind to nuclear c-Yes in PLC/PRF/5 cell line. c-Yes was found to be expressed in the membranes and cytoplasm of HLE, HLF and Hep 3B HCC cells; it was also detected in the nuclei in addition to the membranes and cytoplasm of PLC/PRF/5 HCC cells. HCC with nuclear c-Yes was detected in 5 of 39 cases (13.0%), and nuclear c-Yes expression was not detected in normal, chronic hepatitis or cirrhotic livers. All HCCs with nuclear c-Yes expression were well-differentiated, small tumors at the early stages. In the PLC/PRF/5 cell line, the nuclear localization of c-Yes with cyclin-dependent kinase 1 was confirmed by a protein antibody array. In conclusion, nuclear c-Yes expression was found in cancer cells at the early stages of hepatocarcinogenesis, suggesting that nucleus-located c-Yes may be a useful marker to detect early-stage HCC.

  12. Dose response for TCDD promotion of hepatocarcinogenesis in rats initiated with DEN: histologic, biochemical, and cell proliferation endpoints.

    Science.gov (United States)

    Maronpot, R R; Foley, J F; Takahashi, K; Goldsworthy, T; Clark, G; Tritscher, A; Portier, C; Lucier, G

    1993-12-01

    The present study examines the dose-response relationship for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) promotion of histologic and biochemical parameters by using a two-stage model for hepatocarcinogenesis in female Sprague-Dawley rats initiated with a single intraperitoneal dose of 175 mg of diethylnitrosamine (DEN)/kg body weight at 70 days of age. Starting 2 weeks after initiation, treatment groups of 8-10 rats were given TCDD by gavage in corn oil once every 2 weeks for 30 weeks. Doses were 3.5, 10.7, 35.7, and 125 ng TCDD/kg body weight/day. A significant body weight reduction was present in the noninitiated group that received 125 ng TCDD. Relative liver weight was statistically increased in initiated rats treated with > or = 10.7 ng TCDD and in noninitiated rats treated with > or = 35.7 ng TCDD. Histopathologic evidence of cytotoxicity was dose-related in all TCDD-treated groups. There was a statistically significant dose response in the bromodeoxyuridine (BrdU) S-phase labeling index (LI) in the DEN-initiated rats (p < 0.01) and a marginally significant trend in the saline-treated rats (p = 0.10), but proliferating cell nuclear antigen S-phase LI and growth fraction within altered hepatic foci showed no increase. Among the DEN-initiated groups there was a significant increase in glutathione S-transferase altered hepatic foci stereological parameters in the 125 ng TCDD group. This study demonstrates that dose-response relationships for TCDD's effects on cell proliferation growth of altered hepatic foci are different from previously reported effects on P450 gene expression, indicating that different biological or biochemical responses may exhibit different dose-response relationships.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Water extracts of cabbage and kale inhibit ex vivo H2O2-induced DNA damage but not rat hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    M.A. Horst

    2010-03-01

    Full Text Available The chemopreventive potential of water extracts of the Brassica vegetables cabbage and kale was evaluated by administering their aqueous extracts in drinking water ad libitum to Wistar rats submitted to Ito’s hepatocarcinogenesis model (CB group and K group, respectively - 14 rats per group. Animals submitted to this same model and treated with water were used as controls (W group - 15 rats. Treatment with the vegetable extracts did not inhibit (P > 0.05 placental glutathione S-transferase-positive preneoplastic lesions (PNL. The number of apoptotic bodies did not differ (P > 0.05 among the experimental groups. Ex vivo hydrogen peroxide treatment of rat livers resulted in lower (P < 0.05 DNA strand breakage in cabbage- (107.6 ± 7.8 µm and kale- (110.8 ± 10.0 µm treated animals compared with control (120.9 ± 12.7 µm, as evaluated by the single cell gel (comet assay. Treatment with cabbage (2 ± 0.3 µg/g or kale (4 ± 0.2 µg/g resulted in increased (P < 0.05 hepatic lutein concentration compared with control (0.5 ± 0.07 µg/g. Despite the absence of inhibitory effects of cabbage and kale aqueous extracts on PNL, these Brassica vegetables presented protection against DNA damage, an effect possibly related to increased hepatic lutein concentrations. However, it must be pointed out that the cause-effect relationship between lutein levels and protection is hypothetical and remains to be demonstrated.

  14. Med1 subunit of the mediator complex in nuclear receptor-regulated energy metabolism, liver regeneration, and hepatocarcinogenesis.

    Science.gov (United States)

    Jia, Yuzhi; Viswakarma, Navin; Reddy, Janardan K

    2014-01-01

    Several nuclear receptors regulate diverse metabolic functions that impact on critical biological processes, such as development, differentiation, cellular regeneration, and neoplastic conversion. In the liver, some members of the nuclear receptor family, such as peroxisome proliferator-activated receptors (PPARs), constitutive androstane receptor (CAR), farnesoid X receptor (FXR), liver X receptor (LXR), pregnane X receptor (PXR), glucocorticoid receptor (GR), and others, regulate energy homeostasis, the formation and excretion of bile acids, and detoxification of xenobiotics. Excess energy burning resulting from increases in fatty acid oxidation systems in liver generates reactive oxygen species, and the resulting oxidative damage influences liver regeneration and liver tumor development. These nuclear receptors are important sensors of exogenous activators as well as receptor-specific endogenous ligands. In this regard, gene knockout mouse models revealed that some lipid-metabolizing enzymes generate PPARα-activating ligands, while others such as ACOX1 (fatty acyl-CoA oxidase1) inactivate these endogenous PPARα activators. In the absence of ACOX1, the unmetabolized ACOX1 substrates cause sustained activation of PPARα, and the resulting increase in energy burning leads to hepatocarcinogenesis. Ligand-activated nuclear receptors recruit the multisubunit Mediator complex for RNA polymerase II-dependent gene transcription. Evidence indicates that the Med1 subunit of the Mediator is essential for PPARα, PPARγ, CAR, and GR signaling in liver. Med1 null hepatocytes fail to respond to PPARα activators in that these cells do not show induction of peroxisome proliferation and increases in fatty acid oxidation enzymes. Med1-deficient hepatocytes show no increase in cell proliferation and do not give rise to liver tumors. Identification of nuclear receptor-specific coactivators and Mediator subunits should further our understanding of the complexities of metabolic

  15. A single dose of caffeic acid phenethyl ester prevents initiation in a medium-term rat hepatocarcinogenesis model

    Institute of Scientific and Technical Information of China (English)

    Claudia Esther Carrasco-Legleu; Yesennia Sánchez-Pérez; Lucrecia Márquez-Rosado; Samia Fattel-Fazenda; Evelia Arce-Popoca; Sergio Hernández-García; Saú1 Villa-Trevi(n)o

    2006-01-01

    AIM:To study of the effect of caffeic acid phenethyl ester (CAPE) on the initiation period in a medium-term assay of hepatocarcinogenesis.METHODS: Male Wistar rats were subjected to a carcinogenic treatment (CT) and sacrificed at 25th d;altered hepatic foci (AHF) were generated efficiently.To a second group of rats a single 20 mg/kg doses of CAPE was given 12 h before initiation with CT and were sacrificed at 25th d. We evaluated the expression of preneoplastic markers as y-glutamyltranspeptidase (GGT) and glutathione S-transferase type pi protein (GSTp) by histochemistry, RT-PCR and Western blot analyses, respectively. We measured thiobarbituric acid reactive substances (TBARS) in homogenates of liver and used Unscheduled DNA Synthesis (UDS) assay by incorporation of [3H] thymidine (3HdT) in primary hepatocyte cultures (PHC).RESULTS:At 25th d after CT CAPE reduced the observed increase of GGT+AHF by 84% and liver expression of ggt mRNA by 100%. In case of the GSTp protein, the level was reduced by 90%. As indicative of oxidative stress generated by diethylnitrosamine (DEN) 12 h after its administration, we detected a 68% increase of TBARS.When CAPE was administered before DEN, it completely protected from liver TBARS induction. To have an indication of the sole effect of CAPE on initiation, two carcinogens were tested in a UDS assay in PHC, we used methyl-n-nitrosoguanidine as a direct carcinogen and DEN, as indirect carcinogen. In this assay, genotoxic damage caused by carcinogens was abolished at 5μM CAPE concentration.CONCLUSION:Our results demonstrated that CAPE possesses anti-genotoxic and antineoplastic capabilities,by an anti-oxidative and free-radical scavenging mechanism.

  16. Cancer chemopreventive effect of Spirogyra neglecta (Hassall) Kützing on diethylnitrosamine-induced hepatocarcinogenesis in rats.

    Science.gov (United States)

    Thumvijit, Tarika; Taya, Sirinya; Punvittayagul, Charatda; Peerapornpisal, Yuwadee; Wongpoomchai, Rawiwan

    2014-01-01

    Spirogyra neglecta, a freshwater green alga, is a local food in the northern and northeastern parts of Thailand. This investigation explored the anticarcinogenicity of S neglecta and its possible cancer chemopreventive mechanisms in rats divided into 14 groups. Groups 1 and 10 served as positive and negative control groups, respectively. Groups 1-9 were intraperitoneally injected with diethylnitrosamine (DEN) once a week for 3 weeks. Groups 10-14 received normal saline instead. One week after the last DEN injection, groups 2-5 were administered for 9 consecutive weeks various doses of S neglecta extract (SNE) and dried S neglecta (SND), mixed with basal diet. Groups 6-9 and 11-14 similarly were administered various doses of SNE and SND starting from the first week of the experiment. Administration of SNE and SND was not associated with formation of glutathione-S- transferase placental form (GST-P) positive foci in rat liver. SNE and SND during initiation phase significantly reduced the number of GST-P positive foci in rats injected with DEN. The number of GST-P also diminished in groups treated with SNE and SND after injection with DEN, except for the low dose extract group. SNE showed stronger anticarcinogenic potency than SND. Furthermore, SNE also decreased the number of Ki-67 positive cells. However, the numbers of TUNEL-positive cells in the liver of the SNE-treated groups were not statistically different from the controls. The GST activity in 50 mg/kg bw of SNE and 1% of SND groups was significantly increased as compared to the positive control. In conclusion, Spirogyra neglecta (Hassall) Kutzing showed cancer chemopreventive properties at the early stages of diethylnitrosamine-induced hepatocarcinogenesis in rats. Possible inhibitory mechanisms include enhancement of the activities of some detoxifying enzymes and/or suppression of precancerous cells.

  17. Spectroscopic characterization of lycopene extract from Lycopersicum esculentum (Tomato) and its evaluation as a chemopreventive agent against experimental hepatocarcinogenesis in mice.

    Science.gov (United States)

    Gupta, Prachi; Bansal, Mohinder Pal; Koul, Ashwani

    2013-03-01

    The present study was designed to characterize the lycopene extract (LycT) prepared from tomatoes (Lycopersicum esculentum) and then to evaluate its chemopreventive efficacy in N-diethylnitrosamine (NDEA)-induced experimental hepatocarcinogenesis in female Balb/c mice. The extraction of lycopene was carried out using hexane/acetone/ethanol as an extracting medium and then characterized by ultraviolet-visible, nuclear magnetic resonance and Fourier transform infrared spectroscopy. Chemopreventive efficacy of characterized LycT in vivo was evaluated in terms of hepatic tumour incidence, multiplicity, burden, hepatosomatic index and animal survival rate. Results indicated that average lycopene content of the tomato was 11.6-14 mg/kg tomato weight. Spectroscopic data confirmed the structural characteristics of lycopene in the extract. In the animal study, reduction in tumour incidence (42.05%), tumour burden (1.39) and tumour multiplicity (3.42) was observed upon LycT pretreatment to NDEA-treated animals. Histopathological analysis unravelled that the increased survival rate in LycT + NDEA-treated animals was due to the delay in the formation of aggressive tumour nodules. These observations indicate that lycopene seems to be an able candidate for chemoprevention in hepatocarcinogenesis resulting from NDEA insults.

  18. Expression of IGF-Ⅱ, p53, p21 and HBxAg in precancerous events of hepatocarcinogenesis induced by AFB1 and/or HBV in tree shrews

    Institute of Scientific and Technical Information of China (English)

    Liu Liang Qin; Jian Jia Su; Yuan Li; Chun Yang; Ke Chen Ban; Rue Qi Yian

    2000-01-01

    @@ INTRODUCTION In order to study the relationship between oncogene expression and HCC generation, we observed the precancerous hepatic GGT foci, IGF-Ⅱ, p53 and p21 expression during hepatocarcinogenesis of tree shrew induced by hepatitis B virus (HBV) and/or aflatoxin B1 (AFB1).

  19. Metallic nanostructures for efficient LED lighting

    NARCIS (Netherlands)

    Lozano, G.; Rodriguez, S. R. K.; Verschuuren, M. A.; Rivas, Gomez

    2016-01-01

    Light-emitting diodes (LEDs) are driving a shift toward energy-efficient illumination. Nonetheless, modifying the emission intensities, colors and directionalities of LEDs in specific ways remains a challenge often tackled by incorporating secondary optical components. Metallic nanostructures suppor

  20. Thermal Design for 5 Watt Power LED

    Institute of Scientific and Technical Information of China (English)

    WANG Cai-feng; NIU Ping-juan; GAO Tie-cheng; YANG Guang-hua; FU Xian-song

    2009-01-01

    With the consideration of the thermal management and heat sink requirements, a cooling device is designed and the thermal resistance of this device is calculated with a single 5 W power LED. The thermal design of a single 5 W power LED is reasonable, effective and the result has been simulated. This design also instruct other power LEDs' thermal design. Provided is a reliable and effective method for the design of power LED illumination lamps and lanterns.

  1. Goniometric characterization of LED based greenhouse lighting

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Corell, Dennis Dan;

    2015-01-01

    This paper describes a demonstration of goniospectroradiometry for characterizations of new light emitting diode (LED) based luminaries for enhanced photosynthesis in greenhouses. It highlights the differences between measurement of the traditional high pressure sodium (HPS) luminaries and the LED...... based luminaries. The LED based luminaries are compared to traditional HPS luminaries; in terms of energy efficiency with regard to the photosynthetic photon flux, and the LED luminaries were found to be more effective than the HPS luminaries...

  2. HEPATOPROTECTIVE AND ANTIOXIDANT POTENTIAL OF MORINGA OLEIFERA PODS AGAINST DMBA-INDUCED HEPATOCARCINOGENESIS IN MALE MICE

    Directory of Open Access Journals (Sweden)

    Ritu Paliwal

    2011-06-01

    Full Text Available The importance of Moringa oleifera pods hydroethanolic extract was investigated for its possible hepatoprotective effect in male swiss albino mice against DMBA (synthetic poly aromatic hydrocarbon 7, 12- dimethyl benz(aanthracene induced hepatocarcinogenicity and oxidative stress in hepatic tissues. DMBA exposure elicited a significant escalation in TBARS substances level and depletion in antioxidant enzymes namely superoxide dismutase and catalase in liver. It has been observed that mice treated with MO showed a significant improvement in LPO level along with elevated levels of SOD and CAT activity, which might be the reason for its chemopreventive effect. Phytochemical screening and antioxidant activity of MO clearly indicate that the extract possess antioxidant properties and could serve as free radical inhibitors, acting possibly as primary antioxidants. Finally, these results suggested that M. oleifera pods extract could act against DMBA-induced hepatic injury in mice by a mechanism related to its antioxidant properties and its ability to attenuate the hepatic stellate cells activation. These findings are suggestive of a possible chemopreventive potential of M. oleifera pods extract against chemical carcinogens.

  3. ‘No Blue’ White LED

    DEFF Research Database (Denmark)

    Ou, Haiyan; Corell, Dennis Dan; Dam-Hansen, Carsten

    2010-01-01

    This paper explored the feasibility of making a white LED light source by color mixing method without using the blue color. This ‘no blue’ white LED has potential applications in photolithography room illumination, medical treatment and biophotonics research. A no-blue LED was designed, and the p...

  4. Hepatoprotective effect of engineered silver nanoparticles coated bioactive compounds against diethylnitrosamine induced hepatocarcinogenesis in experimental mice.

    Science.gov (United States)

    Prasannaraj, Govindaraj; Venkatachalam, Perumal

    2017-02-01

    Nanoparticle based drug delivery can rapidly improves the therapeutic potential of anti-cancer agents. The present study focused to evaluate the hepatoprotective activity of silver nanoparticles (AgNPs) synthesized using aqueous extracts of Andrographis paniculata leaves (ApAgNPs) and Semecarpus anacardium nuts (SaAgNPs) against diethylnitrosamine (DEN) induced liver cancer in mice model. The physico-chemical properties of synthesized AgNPs were characterized by Fourier transform infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX) spectrum, Zeta potential and Dynamic Light Scattering (DLS) analysis. The surface plasmon resonance (SPR) absorption spectrum revealed a strong peak at 420nm for both SaAgNPs and ApAgNPs. FTIR results exhibited the presence of possible functional groups in the synthesized AgNPs. TEM analysis determined the hexagonal, and spherical shape of the synthesized silver nanoparticles. The XRD and SAED pattern confirmed the crystalline nature and crystalline size of the AgNPs. EDX result clearly showed strong silver signals in the range between 2 and 4keV. Zeta potential measurements indicated a sharp peak at -3.93 and -13.8mV for ApAgNPs and SaAgNPs, respectively. DLS measurement expressed the particle size distribution was 70 and 60nm for ApAgNPs and SaAgNPs, respectively. DEN (20mg/kg b.wt.) was subjected to induce liver cancer in mice for 8weeks and treated with biosynthesized silver nanoparticles. Interestingly, ApAgNPs and SaAgNPs treated DEN induced animal groups show a decreased level of aspartate amino transferase (AST), alanine amino transferase (ALT), serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) activity and elevated level of catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) and superoxide dismutase (SOD) activity over untreated DEN control

  5. Generation of solar spectrum by using LEDs

    Science.gov (United States)

    Lu, Pengzhi; Yang, Hua; Pei, Yanrong; Li, Jing; Xue, Bin; Wang, Junxi; Li, Jinmin

    2016-09-01

    Light emitting diode (LED) has been recognized as an applicable light source for indoor and outdoor lighting, city beautifying, landscape facilities, and municipal engineering etc. Conventional LED has superior characteristics such as long life time, low power consumption, high contrast, and wide viewing angle. Recently, LED with high color-rendering index and special spectral characteristics has received more and more attention. This paper is intended to report a solar spectrum simulated by multichip LED light source. The typical solar spectrum of 5500k released by CIE was simulated as a reference. Four types of LEDs with different spectral power distributions would be used in the LED light source, which included a 430nm LED, a 480nm LED, a 500nm LED and a white LED. In order to obtain better simulation results, the white LED was achieved by a 450nm LED chip with the mixture of phosphor. The phosphor combination was prepared by mixing green phosphor, yellow phosphor and red phosphor in a certain proportion. The multichip LED light source could provide a high fidelity spectral match with the typical solar spectrum of 5500k by adjusting injection current to each device. The luminous flux, CIE chromaticity coordinate x, y, CCT, and Ra were 104.7 lm, 0.3337, 0.3681, 5460K, and 88.6, respectively. Because of high color-rendering index and highly match to the solar spectrum, the multichip LED light source is a competitive candidate for applications where special spectral is required, such as colorimetric measurements, visual inspection, gemstone identification and agriculture.

  6. Protective action of an anti-oxidant (L-Ascorbic acid against genotoxicity and cytotoxicity in mice during p-DAB-induced hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Surjyo B

    2004-01-01

    Full Text Available BACKGROUND : DNA damage from micronutrient deficiencies has been suggested as one major cause of cancer. Therefore studies involving vitamin supplementaion , particularly with those with anti-oxidant activity, in combating cancer have routinely been carried out in both in vivo and in vitro systems, but relatively much less in mice. AIMS : The present study examines if L-Ascorbic acid (AA; vitamin C administration has any protective abilities in combating p-DAB induced hepatocarcinogenesis in mice at cytogenetical, biochemical, histological and ultra-structural levels. SETTINGS AND DESIGN : To test if AA had a protective action against genotoxicity, cytotoxicity and tissue damage in liver during p-dimethylaminoazobenezene (p-DAB induced hepatocarcinogenesis in mice, a group of mice were chronically fed 0.06% p-DAB and 0.05% phenobarbital (PB for a varying period of time (7, 15, 30, 60, 90 and 120 days. A sub-group of the p-DAB plus PB fed mice were also fed 1% L-ascorbic acid. Several assays were periodically conducted (at the six intervals of fixation for determination of genotoxic (based on chromosomal, nuclear and sperm head anomalies, cytotoxic (based on the marker enzymes aspartate transaminase; AST, alanine aminotransferase; ALT; acid phosphatase; ACP; alkaline phosphatase; ALKP; lipid peroxidation; LPO; and tissue damaging (based on optical and electron microscopic studies of liver at day 60 only effects in these different groups of mice as compared to normal healthy control. METHODS AND MATERIAL: Adult healthy mice of Swiss Albino strain, reared and maintained in the animal house of the Department of Zoology,. Kalyani University, under supervision of Animal Welfare Committee (which oversees ethical issues, served as materials for the present study. Widely practiced standard technique has been followed for each protocol. STATISTICAL ANALYSIS USED: The significance test between different series of data was conducted by student¢s t

  7. White LED visible light communication technology research

    Science.gov (United States)

    Yang, Chao

    2017-03-01

    Visible light communication is a new type of wireless optical communication technology. White LED to the success of development, the LED lighting technology is facing a new revolution. Because the LED has high sensitivity, modulation, the advantages of good performance, large transmission power, can make it in light transmission light signal at the same time. Use white LED light-emitting characteristics, on the modulation signals to the visible light transmission, can constitute a LED visible light communication system. We built a small visible optical communication system. The system composition and structure has certain value in the field of practical application, and we also research the key technology of transmitters and receivers, the key problem has been resolved. By studying on the optical and LED the characteristics of a high speed modulation driving circuit and a high sensitive receiving circuit was designed. And information transmission through the single chip microcomputer test, a preliminary verification has realized the data transmission function.

  8. Thermal Performance Analysis of LED with Multichips

    Institute of Scientific and Technical Information of China (English)

    HAN Yuanyuan; GUO Hong; ZHANG Ximin; YIN Fazhang; CHU Ke; FAN Yeming

    2011-01-01

    The package and system level temperature and thermal stress distributions of 10 W light emitting diode (LED) with 4 chips and 100 W LED with 100 chips were investigated using finite element analysis.The chips were arranged on a Si sheet which is soldered on the copper/diamond composite slug with very high conductivity.The experimental results show that the maximal temperature appears in the chips of both two high power LEDs packages.Compared with the 10 W LEDs package with 4 chips array,the heat issue caused by stacking and coupling of the heat in 100 W LEDs package with 100 chips array is more serious.The chip temperature in the center of the array is much higher,and it decreases with the distance between the chip and the center of LEDs increases.Great thermal stress lies between the chips and the solder,which will reduce the reliability of the package.

  9. New paradigms in LED photometry and colorimetry

    Science.gov (United States)

    Estrada-Hernández, A.; González-Galván, L. P.; Rosas, E.

    2009-09-01

    Motivated by the growing number of applications the light emitting diodes, LEDs, are having in solid-state lighting systems, we summarize the new internationally standardized measurement methods for photometric and colorimetric quantities in LEDs; since they are commonly used to quantify some of the key performance parameters of several products used in automotive industry, traffic signaling, etc. Finally, special emphasis is given to the mismatch corrections factors calculation, and its use when measuring LEDs photometric and colorimetric quantities.

  10. System Reliability for LED-Based Products

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J Lynn; Mills, Karmann; Lamvik, Michael; Yaga, Robert; Shepherd, Sarah D; Bittle, James; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy; Johnson, Cortina; Evans, Amy

    2014-04-07

    Results from accelerated life tests (ALT) on mass-produced commercially available 6” downlights are reported along with results from commercial LEDs. The luminaires capture many of the design features found in modern luminaires. In general, a systems perspective is required to understand the reliability of these devices since LED failure is rare. In contrast, components such as drivers, lenses, and reflector are more likely to impact luminaire reliability than LEDs.

  11. Wide reflected angle DBR red light LED

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The coupled DBR LED with one DBR for reflecting normal incidence light and the other for reflecting inclined incidence light has been grown by MOCVD. For improving the conventional DBR which was used to increase light extraction efficiency in A1GaInP red light LED is analyzed. At 20 mA Dc injection current, the LED peak wave length is 630 nm, and the light intensity of on axis is 137 mcd. The output light power is 2.32 mW. The light intensity and output light power have been improved compared with the conventional LEDs.

  12. Projecting LED product life based on application

    Science.gov (United States)

    Narendran, Nadarajah; Liu, Yi-wei; Mou, Xi; Thotagamuwa, Dinusha R.; Eshwarage, Oshadhi V. Madihe

    2016-09-01

    LED products have started to displace traditional light sources in many lighting applications. One of the commonly claimed benefits for LED lighting products is their long useful lifetime in applications. Today there are many replacement lamp products using LEDs in the marketplace. Typically, lifetime claims of these replacement lamps are in the 25,000-hour range. According to current industry practice, the time for the LED light output to reach the 70% value is estimated according to IESNA LM-80 and TM-21 procedures and the resulting value is reported as the whole system life. LED products generally experience different thermal environments and switching (on-off cycling) patterns when used in applications. Current industry test methods often do not produce accurate lifetime estimates for LED systems because only one component of the system, namely the LED, is tested under a continuous-on burning condition without switching on and off, and because they estimate for only one failure type, lumen depreciation. The objective of the study presented in this manuscript was to develop a test method that could help predict LED system life in any application by testing the whole LED system, including on-off power cycling with sufficient dwell time, and considering both failure types, catastrophic and parametric. The study results showed for the LED A-lamps tested in this study, both failure types, catastrophic and parametric, exist. The on-off cycling encourages catastrophic failure, and maximum operating temperature influences the lumen depreciation rate and parametric failure time. It was also clear that LED system life is negatively affected by on-off switching, contrary to commonly held belief. In addition, the study results showed that most of the LED systems failed catastrophically much ahead of the LED light output reaching the 70% value. This emphasizes the fact that life testing of LED systems must consider catastrophic failure in addition to lumen depreciation, and

  13. Chemopreventive effect of Fumaria indica that modulates the oxidant-antioxidant imbalance during N-nitrosodiethylamine and CCl4-induced hepatocarcinogenesis in Wistar rats

    Institute of Scientific and Technical Information of China (English)

    Talib Hussain; Hefazat H Siddiqui; Sheeba Fareed; K Sweety; M Vijayakumar; Chandana V Rao

    2012-01-01

    Objective: To investigation the chemopreventive efficiency of Fumaria indica extract (FIE) on the antioxidant status of N-nitrosodiethylamine (NDEA) and CCl4-induced hepatocarcinogenesis in Wistar rats. Methods: The experimental animals were divided into six groups (n = 6). HCC was induced by single intraperitoneal injection of NDEA in normal saline at a dose of 200 mg/kg body weight followed by weekly subcutaneous injections of CCl4 (3 mL/kg/week) for 6 weeks, as the promoter of carcinogenic effect. After administration of the carcinogen, 200 and 400 mg/kg of FIE were administered orally once a day throughout the study. At the end of 20 weeks, the body weight, liver weight and relative liver weight were measured. The level of hepatic malondialdehyde (MDA) formation, reduced glutathione (GSH) and the activities of antioxidant enzymes viz. CAT, SOD, GPx, and GST in the liver of NDEA and CCL4-treated rats were assessed. Results: Obtained results demonstrated that the cotreatment with FIE (200 and 400 mg/kg) significantly prevented the decrease of the body weight and also increased in relative liver weight caused by NDEA and CCl4 administration. FIE also significantly prevented hepatic malondialdehyde (MDA) formation and reduced glutathione (GSH) in NDEA-treated rats which were dose dependent. Additionally, FIE also markedly increased the activities of antioxidant enzymes such as CAT, SOD, GPx, and GST in the liver of NDEA and CCL4-treated rats. Conclusions: These finding powerfully supports thatFumaria indica exert a chemopreventive effect by reversing the oxidant-antioxidant imbalance during hepatocarcinogenesis induced by NDEA and CCl4.

  14. Suppressing activity of tributyrin on hepatocarcinogenesis is associated with inhibiting the p53-CRM1 interaction and changing the cellular compartmentalization of p53 protein.

    Science.gov (United States)

    Ortega, Juliana F; de Conti, Aline; Tryndyak, Volodymyr; Furtado, Kelly S; Heidor, Renato; Horst, Maria Aderuza; Fernandes, Laura Helena Gasparini; Tavares, Paulo Eduardo Latorre Martins; Pogribna, Marta; Shpyleva, Svitlana; Beland, Frederick A; Pogribny, Igor P; Moreno, Fernando Salvador

    2016-04-26

    Hepatocellular carcinoma (HCC), an aggressive and the fastest growing life-threatening cancer worldwide, is often diagnosed at intermediate or advanced stages of the disease, which substantially limits therapeutic approaches for its successful treatment. This indicates that the prevention of hepatocarcinogenesis is probably the most promising approach to reduce both the HCC incidence and cancer-related mortality. In previous studies, we demonstrated a potent chemopreventive effect of tributyrin, a butyric acid prodrug, on experimental hepatocarcinogenesis. The cancer-inhibitory effect of tributyrin was linked to the suppression of sustained cell proliferation and induction of apoptotic cell death driven by an activation of the p53 apoptotic signaling pathway. The goal of the present study was to investigate the underlying molecular mechanisms linked to tributyrin-mediated p53 activation. Using in vivo and in vitro models of liver cancer, we demonstrate that an increase in the level of p53 protein in nuclei, a decrease in the level of cytoplasmic p53, and, consequently, an increase in the ratio of nuclear/cytoplasmic p53 in rat preneoplastic livers and in rat and human HCC cell lines caused by tributyrin or sodium butyrate treatments was associated with a marked increase in the level of nuclear chromosome region maintenance 1 (CRM1) protein. Mechanistically, the increase in the level of nuclear p53 protein was associated with a substantially reduced binding interaction between CRM1 and p53. The results demonstrate that the cancer-inhibitory activity of sodium butyrate and its derivatives on liver carcinogenesis may be attributed to retention of p53 and CRM1 proteins in the nucleus, an event that may trigger activation of p53-mediated apoptotic cell death in neoplastic cells.

  15. Hepatitis B virus X protein induces the histone H3 lysine 9 trimethylation on the promoter of p16 gene in hepatocarcinogenesis.

    Science.gov (United States)

    Wang, Di-Yi; Zou, Li-Ping; Liu, Xiao-Jia; Zhu, Hong-Guang; Zhu, Rong

    2015-12-01

    Our previous study showed hepatitis B virus X protein (HBx) suppresses the p16 expression in hepatocarcinogenesis. In this study we explored the relationship between HBx and trimethylation of H3K9 (H3K9me3), and elucidated the underlying mechanisms in HBx inducing the tumor suppressor p16 gene silence. SMMC-7721 and HepG2 hepatoma cell lines were transfected with HBx-expressing plasmid. Immunohistochemistry, Western blotting and real-time polymerase chain reaction, were performed to detect the expressions of HBx, H3K9me3, and jumonji domain-containing protein 2B (JMJd2B). H3K9me3 enrichment on the p16 promoter was measured by immunoprecipitation-PCR (ChIP-PCR) analyses, and 39 cases of hepatitis B virus (HBV) associated-hepatocellular carcinoma (HCC) and corresponding noncancerous liver tissues were also examined. We demonstrated that HBx was able to upregulate H3K9me3 and suppress JMJd2B mRNA and protein levels in SMMC-7721 and HepG2 hepatoma cell lines. JMJd2B, as a specific target of H3K9me3 for demethylation, was inversely correlated with the levels of H3K9me3 in SMMC-7721 (r=-0.666, Pp16 promoter region. Immunohistochemistry analysis showed that H3K9me3 expression in HBx positive HCC samples were significantly higher than that in HBx negative HCC tissues and were associated with decreased levels of JMJd2B expression. JMJd2B immunoreactivity was also remarkably inversed to that of HBx in HCC tissues (r=-0.630, Pp16 promoter via the decrease of demethylase JMJd2B expression and thus promote the repression of p16 gene expression to enhance hepatocarcinogenesis.

  16. Reduced Component Count RGB LED Driver

    NARCIS (Netherlands)

    De Pedro, I.; Ackermann, B.

    2008-01-01

    The goal of this master thesis is to develop new drive and contrololutions, for creating white light from mixing the light of different-color LEDs, aiming at a reduced component count resulting in less space required by the electronics and lower cost. It evaluates the LED driver concept proposed in

  17. Led Zeppelin reklaamib Narvat / Anti Ronk

    Index Scriptorium Estoniae

    Ronk, Anti

    2007-01-01

    Ilmus Narva-teemaline kahest CD-st koosnev album, kus ühel plaadil on 60 minutit videot linna vaatamisväärsuste ja informatsiooniga, teisel - briti rockansambli Led Zeppelini teosed Narva sümfooniaorkestri ja rockansambli Led R esituses

  18. Advances in LEDs for automotive applications

    Science.gov (United States)

    Bhardwaj, Jy; Peddada, Rao; Spinger, Benno

    2016-03-01

    High power LEDs were introduced in automotive headlights in 2006-2007, for example as full LED headlights in the Audi R8 or low beam in Lexus. Since then, LED headlighting has become established in premium and volume automotive segments and beginning to enable new compact form factors such as distributed low beam and new functions such as adaptive driving beam. New generations of highly versatile high power LEDs are emerging to meet these application needs. In this paper, we will detail ongoing advances in LED technology that enable revolutionary styling, performance and adaptive control in automotive headlights. As the standards which govern the necessary lumens on the road are well established, increasing luminance enables not only more design freedom but also headlight cost reduction with space and weight saving through more compact optics. Adaptive headlighting is based on LED pixelation and requires high contrast, high luminance, smaller LEDs with high-packing density for pixelated Matrix Lighting sources. Matrix applications require an extremely tight tolerance on not only the X, Y placement accuracy, but also on the Z height of the LEDs given the precision optics used to image the LEDs onto the road. A new generation of chip scale packaged (CSP) LEDs based on Wafer Level Packaging (WLP) have been developed to meet these needs, offering a form factor less than 20% increase over the LED emitter surface footprint. These miniature LEDs are surface mount devices compatible with automated tools for L2 board direct attach (without the need for an interposer or L1 substrate), meeting the high position accuracy as well as the optical and thermal performance. To illustrate the versatility of the CSP LEDs, we will show the results of, firstly, a reflector-based distributed low beam using multiple individual cavities each with only 20mm height and secondly 3x4 to 3x28 Matrix arrays for adaptive full beam. Also a few key trends in rear lighting and impact on LED light

  19. Using LEDs to reduce energy consumption

    Science.gov (United States)

    Eweni, Chukwuebuka E.

    The most popularly used light bulb in homes is the incandescent. It is also the least energy efficient. The filament in the bulb is so thin that it causes resistance in the electricity, which in turn causes the electricity's energy to form heat. This causes the incandescent to waste a lot of energy forming heat rather than forming the light. It uses 15 lumens per watt of input power. A recorded MATLAB demonstration showcased LED versatility and how it can be used by an Arduino UNO board. The objective of this thesis is to showcase how LEDs can reduce energy consumption through the use of an Arduino UNO board and MATLAB and to discuss the applications of LED. LED will be the future of lighting homes and will eventually completely incandescent bulbs when companies begin to make the necessary improvements to the LED.

  20. Accurate colorimetric feedback for RGB LED clusters

    Science.gov (United States)

    Man, Kwong; Ashdown, Ian

    2006-08-01

    We present an empirical model of LED emission spectra that is applicable to both InGaN and AlInGaP high-flux LEDs, and which accurately predicts their relative spectral power distributions over a wide range of LED junction temperatures. We further demonstrate with laboratory measurements that changes in LED spectral power distribution with temperature can be accurately predicted with first- or second-order equations. This provides the basis for a real-time colorimetric feedback system for RGB LED clusters that can maintain the chromaticity of white light at constant intensity to within +/-0.003 Δuv over a range of 45 degrees Celsius, and to within 0.01 Δuv when dimmed over an intensity range of 10:1.

  1. White LEDs with limit luminous efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Lisitsyn, V. M.; Stepanov, S. A., E-mail: stepanovsa@tpu.ru; Yangyang, Ju [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Lukash, V. S. [JSC Research Institute of Semiconductor Devices, 99a Krasnoarmeyskaja St., Tomsk, 634050 (Russian Federation)

    2016-01-15

    In most promising widespread gallium nitride based LEDs emission is generated in the blue spectral region with a maximum at about 450 nm which is converted to visible light with the desired spectrum by means of phosphor. The thermal energy in the conversion is determined by the difference in the energies of excitation and emission quanta and the phosphor quantum yield. Heat losses manifest themselves as decrease in the luminous efficacy. LED heating significantly reduces its efficiency and life. In addition, while heating, the emission generation output and the efficiency of the emission conversion decrease. Therefore, the reduction of the energy losses caused by heating is crucial for LED development. In this paper, heat losses in phosphor-converted LEDs (hereinafter chips) during spectrum conversion are estimated. The limit values of the luminous efficacy for white LEDs are evaluated.

  2. High Performance Green LEDs by Homoepitaxial

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, Christian; Schubert, E Fred

    2009-11-22

    This work's objective was the development of processes to double or triple the light output power from green and deep green (525 - 555 nm) AlGaInN light emitting diode (LED) dies within 3 years in reference to the Lumileds Luxeon II. The project paid particular effort to all aspects of the internal generation efficiency of light. LEDs in this spectral region show the highest potential for significant performance boosts and enable the realization of phosphor-free white LEDs comprised by red-green-blue LED modules. Such modules will perform at and outperform the efficacy target projections for white-light LED systems in the Department of Energy's accelerated roadmap of the SSL initiative.

  3. White LED with High Package Extraction Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Yi Zheng; Matthew Stough

    2008-09-30

    The goal of this project is to develop a high efficiency phosphor converting (white) Light Emitting Diode (pcLED) 1-Watt package through an increase in package extraction efficiency. A transparent/translucent monolithic phosphor is proposed to replace the powdered phosphor to reduce the scattering caused by phosphor particles. Additionally, a multi-layer thin film selectively reflecting filter is proposed between blue LED die and phosphor layer to recover inward yellow emission. At the end of the project we expect to recycle approximately 50% of the unrecovered backward light in current package construction, and develop a pcLED device with 80 lm/W{sub e} using our technology improvements and commercially available chip/package source. The success of the project will benefit luminous efficacy of white LEDs by increasing package extraction efficiency. In most phosphor-converting white LEDs, the white color is obtained by combining a blue LED die (or chip) with a powdered phosphor layer. The phosphor partially absorbs the blue light from the LED die and converts it into a broad green-yellow emission. The mixture of the transmitted blue light and green-yellow light emerging gives white light. There are two major drawbacks for current pcLEDs in terms of package extraction efficiency. The first is light scattering caused by phosphor particles. When the blue photons from the chip strike the phosphor particles, some blue light will be scattered by phosphor particles. Converted yellow emission photons are also scattered. A portion of scattered light is in the backward direction toward the die. The amount of this backward light varies and depends in part on the particle size of phosphors. The other drawback is that yellow emission from phosphor powders is isotropic. Although some backward light can be recovered by the reflector in current LED packages, there is still a portion of backward light that will be absorbed inside the package and further converted to heat. Heat

  4. Remote monitoring of LED lighting system performance

    Science.gov (United States)

    Thotagamuwa, Dinusha R.; Perera, Indika U.; Narendran, Nadarajah

    2016-09-01

    The concept of connected lighting systems using LED lighting for the creation of intelligent buildings is becoming attractive to building owners and managers. In this application, the two most important parameters include power demand and the remaining useful life of the LED fixtures. The first enables energy-efficient buildings and the second helps building managers schedule maintenance services. The failure of an LED lighting system can be parametric (such as lumen depreciation) or catastrophic (such as complete cessation of light). Catastrophic failures in LED lighting systems can create serious consequences in safety critical and emergency applications. Therefore, both failure mechanisms must be considered and the shorter of the two must be used as the failure time. Furthermore, because of significant variation between the useful lives of similar products, it is difficult to accurately predict the life of LED systems. Real-time data gathering and analysis of key operating parameters of LED systems can enable the accurate estimation of the useful life of a lighting system. This paper demonstrates the use of a data-driven method (Euclidean distance) to monitor the performance of an LED lighting system and predict its time to failure.

  5. High Power UV LED Industrial Curing Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karlicek, Robert, F., Jr; Sargent, Robert

    2012-05-14

    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  6. High-power LED package requirements

    Science.gov (United States)

    Wall, Frank; Martin, Paul S.; Harbers, Gerard

    2004-01-01

    Power LEDs have evolved from simple indicators into illumination devices. For general lighting applications, where the objective is to light up an area, white LED arrays have been utilized to serve that function. Cost constraints will soon drive the industry to provide a discrete lighting solution. Early on, that will mean increasing the power densities while quantum efficiencies are addressed. For applications such as automotive headlamps & projection, where light needs to be tightly collimated, or controlled, arrays of die or LEDs will not be able to satisfy the requirements & limitations defined by etendue. Ultimately, whether a luminaire requires a small source with high luminance, or light spread over a general area, economics will force the evolution of the illumination LED into a compact discrete high power package. How the customer interfaces with this new package should be an important element considered early on in the design cycle. If an LED footprint of adequate size is not provided, it may prove impossible for the customer, or end user, to get rid of the heat in a manner sufficient to prevent premature LED light output degradation. Therefore it is critical, for maintaining expected LED lifetime & light output, that thermal performance parameters be defined, by design, at the system level, which includes heat sinking methods & interface materials or methdology.

  7. Experimental study of negative capacitance in LEDs

    Institute of Scientific and Technical Information of China (English)

    FENG Lie-feng; WANG Jun; ZHU Chuan-yun; CONG Hong-xia; CHEN Yong; WANG Cun-da

    2005-01-01

    The experimental study on negative capacitance(NC) of various light-emitting diodes(LEDs) is presented.Experimental result shows that all LEDs display the NC phenomenon.The voltage modulated electroluminescence(VMEL) experiment confirms that the reason of negative capacitance is the strong recombination of the injected carriers in the active region of luminescence.The measures also verify that the dependence of NC on voltage and frequency in different LEDs is similar: NC phenomenon is more obvious with higher voltage or lower frequency.

  8. Heterostructures for Increased Quantum Efficiency in Nitride LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Robert F. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2010-09-30

    Task 1. Development of an advanced LED simulator useful for the design of efficient nitride-based devices. Simulator will contain graphical interface software that can be used to specify the device structure, the material parameters, the operating conditions and the desired output results. Task 2. Theoretical and experimental investigations regarding the influence on the microstructure, defect concentration, mechanical stress and strain and IQE of controlled changes in the chemistry and process route of deposition of the buffer layer underlying the active region of nitride-based blue- and greenemitting LEDs. Task 3. Theoretical and experimental investigations regarding the influence on the physical properties including polarization and IQE of controlled changes in the geometry, chemistry, defect density, and microstructure of components in the active region of nitride-based blue- and green-emitting LEDs. Task 4. Theoretical and experimental investigations regarding the influence on IQE of novel heterostructure designs to funnel carriers into the active region for enhanced recombination efficiency and elimination of diffusion beyond this region. Task 5. Theoretical and experimental investigations regarding the influence of enhanced p-type doping on the chemical, electrical, and microstructural characteristics of the acceptor-doped layers, the hole injection levels at Ohmic contacts, the specific contact resistivity and the IQE of nitride-based blue- and green-emitting LEDs. Development and optical and electrical characterization of reflective Ohmic contacts to n- and p-type GaN films.

  9. Computational Techniques for LED Optical Microcavities

    OpenAIRE

    García Santiago, Xavier

    2015-01-01

    The project consist on the development of numerical methods and computational techniques to model the processes of light extraction in power LED (Light-Emitting Diodes) devices. We aim at the use of complex corrugated microstructures to boost the efficiency of our current LUXEON LED products. In order to study extraction efficiency in these devices a 3D optics model of thin film micro-structures must be developed and tested. In this project we develop a numerical model for computing and st...

  10. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products, Part 3: LED Environmental Testing

    Energy Technology Data Exchange (ETDEWEB)

    Tuenge, Jason R.; Hollomon, Brad; Dillon, Heather E.; Snowden-Swan, Lesley J.

    2013-03-01

    This report covers the third part of a larger U.S. Department of Energy (DOE) project to assess the life-cycle environmental and resource impacts in the manufacturing, transport, use, and disposal of light-emitting diode (LED) lighting products in relation to incumbent lighting technologies. All three reports are available on the DOE website (www.ssl.energy.gov/tech_reports.html). • Part 1: Review of the Life-Cycle Energy Consumption of Incandescent, Compact Fluorescent and LED Lamps; • Part 2: LED Manufacturing and Performance; • Part 3: LED Environmental Testing. Parts 1 and 2 were published in February and June 2012, respectively. The Part 1 report included a summary of the life-cycle assessment (LCA) process and methodology, provided a literature review of more than 25 existing LCA studies of various lamp types, and performed a meta-analysis comparing LED lamps with incandescent and compact fluorescent lamps (CFLs). Drawing from the Part 1 findings, Part 2 performed a more detailed assessment of the LED manufacturing process and used these findings to provide a comparative LCA taking into consideration a wider range of environmental impacts. Both reports concluded that the life-cycle environmental impact of a given lamp is dominated by the energy used during lamp operation—the upstream generation of electricity drives the total environmental footprint of the product. However, a more detailed understanding of end-of-life disposal considerations for LED products has become increasingly important as their installation base has grown. The Part 3 study (reported herein) was undertaken to augment the LCA findings with chemical analysis of a variety of LED, CFL, and incandescent lamps using standard testing procedures. A total of 22 samples, representing 11 different models, were tested to determine whether any of 17 elements were present at levels exceeding California or Federal regulatory thresholds for hazardous waste. Key findings include: • The selected

  11. LEDS GP Success Story: Fostering Coordinated LEDS Support in Kenya (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2014-03-01

    The LEDS Global Partnership (LEDS GP) strives to advance climate-resilient, low-emission development through catalyzing collaboration, information exchange, and action on the ground. The Government of Kenya is a key LEDS GP member and offers an inspiring example of how LEDS GP is having an impact globally. The 2012 LEDS Collaboration in Action workshop in London provided an interactive space for members to share experiences on cross-ministerial LEDS leadership and to learn about concrete development impacts of LEDS around the world. Inspired by these stories, the Kenya's Ministry of State for Planning, National Development and Vision 2030 (MPND) began to collaborate closely with the Ministry of Environment and Mineral Resources to create strong links between climate change action and development in the country, culminating in the integration of Kenya's National Climate Change Action Plan and the country's Medium Term Development Plan.

  12. Promoter-region hypermethylation and expression downregulation of Yy1 (Yin yang 1) in preneoplastic liver lesions in a thioacetamide rat hepatocarcinogenesis model

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Hajime [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193 (Japan); Ogawa, Takashi; Wang, Liyun [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Kimura, Masayuki; Tanaka, Takeshi; Morita, Reiko [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193 (Japan); Yoshida, Toshinori [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan); Shibutani, Makoto, E-mail: mshibuta@cc.tuat.ac.jp [Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509 (Japan)

    2014-11-01

    Thioacetamide (TAA) has been used to develop a rodent model for hepatocarcinogenesis. To determine the genes with epigenetic modifications in early hepatocarcinogenesis, we did a genome-wide scan for hypermethylated promoter regions using CpG island microarrays in TAA-promoted rat liver tissue. Eight genes were selected based on the microarray profile; of these, Yy1 and Wdr45b were confirmed to be hypermethylated by methylation-specific polymerase chain reaction (PCR) and pyrosequencing and downregulated by real-time reverse transcription PCR. Non-neoplastic liver cells had nuclear Yy1 immunoreactivity, while preneoplastic foci with glutathione S-transferase placental form (GST-P) immunoreactivity had decreased Yy1 immunoreactivity. The incidence of these foci was proportional to the dose of TAA administered. Co-expression analysis of gene products downstream of Yy1 revealed increased nuclear phospho-c-Myc{sup +} foci as well as nuclear and cytoplasmic p21{sup Cip1+} foci in Yy1{sup −} or GST-P{sup +} foci in response to TAA-promotion dose. Although the absolute number of cells was low, the incidence of death receptor 5{sup −} foci was increased in Yy1{sup −} foci in proportion to the TAA dose. Yy1{sup −}/GST-P{sup +} foci revealed a higher number of proliferating cell nuclear antigen (PCNA)-immunoreactive cells than Yy1{sup +}/GST-P{sup +} foci, while cleaved caspase-3{sup +} cells were unchanged between Yy1{sup –}/GST-P{sup +} and Yy1{sup +}/GST-P{sup +} foci. In the case of Wdr45b, most GST-P{sup +} foci were Wdr45b{sup –} and were not increased by TAA promotion. These results suggest involvement of Yy1 in the epigenetic gene regulation at the early stages of TAA promoted cell proliferation and concomitant cell cycle arrest in preneoplastic lesions. - Highlights: • Epigenetically downregulated genes were searched in TAA-promnoted rat livers. • Yy1 and Wdr45b showed promoter-region hypermethylation and mRNA downregulation. • TAA promoted

  13. Enhancement of N-nitrosodiethylamine-initiated hepatocarcinogenesis by phentoin in male F344/NCr rats at a dose causing maximal induction of CYP2B.

    Science.gov (United States)

    Diwan, B A; Henneman, J R; Nims, R W

    2001-01-01

    The effect of the clinically important anticonvulsant phenytoin (DPH) on hepatocarcinogenesis of male F344/NCr rats initiated with a single i.p. dose of N-nitrosodiethylamine (75 mg/kg b.w.) was studied. Beginning 2 weeks post-initiation, the rats received control diet or diet containing 500 or 1,500 ppm DPH or 500 ppm phenobarbital. At 52 weeks age, the incidences (and multiplicities, in units of tumors per tumor-bearing rat) of hepatocellular adenomas were 0%, 17% (1 +/- 0), 42% (1.8 +/- 0.8), or 67% (2.5 +/- 1.9) in rats exposed to N-nitrosodiethylamine alone, or the carcinogen followed by 500 ppm DPH, 1,500 ppm DPH, or 500 ppm phenobarbital, respectively. Between 53 and 79 weeks of age, 39% of rats receiving N-nitrosodiethylamine alone developed multiple (1.5 +/- 0.8) hepatocellular adenomas. A similar incidence (41%) occurred in the rats administered the carcinogen followed by 500 ppm DPH. The incidence of hepatocellular adenomas (88% and 89%) was significantly greater in rats exposed to N-nitrosodiethylamine followed by 1,500 ppm DPH or 500 ppm phenobarbital, respectively. Multiplicities of hepatocellular adenomas were significantly greater than the control value in rats fed 1,500 ppm DPH or 500 ppm phenobarbital (5.9 +/- 4.8 and 10.1 +/- 6.7, respectively), but not in the rats receiving 500 ppm DPH (2.3 +/- 1.6). No rats exposed to N-nitrosodiethylamine alone or the carcinogen followed by 500 ppm DPH developed hepatocellular carcinomas, while hepatocellular carcinomas occurred in 29% or 67% of the rats given 1,500 ppm DPH or 500 ppm phenobarbital, respectively, following initiation. Increases in hepatic CYP2B-mediated benzyloxyresorufin O-dealkylation activity in rats exposed to 500 and 1,500 ppm DPH for 2 or 23 weeks were approximately 50% and approximately 100%, respectively, of the maximal induction caused by 500 ppm phenobarbital. Thus, in the rat model, DPH enhanced N-nitrosodiethyl-amine-initiated hepatocarcinogenesis when administered at a dose

  14. Affordable underwater wireless optical communication using LEDs

    Science.gov (United States)

    Pilipenko, Vladimir; Arnon, Shlomi

    2013-09-01

    In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

  15. Application of magnetic resonance imaging in transgenic and chemical mouse models of hepatocellular carcinoma

    Directory of Open Access Journals (Sweden)

    Liedtke Christian

    2010-04-01

    Full Text Available Abstract Background Hepatocellular carcinoma (HCC is one of the most common cancers worldwide. The molecular mechanisms underlying hepatocarcinogenesis are still poorly understood. Genetically modified mice are powerful tools to further investigate the mechanisms of HCC development. However, this approach is limited due to the lack of non-invasive detection methods in small rodents. The aim of this study was to establish a protocol for the non-invasive analysis of hepatocarcinogenesis in transgenic mice using a clinical 1.5 Tesla Magnetic Resonance Imaging scanner. Results As a model system we used hepatocyte-specific c-myc transgenic mice developing hepatocellular carcinoma at the age of 12-15 months. The scans of the murine livers included axial T2-weighted turbo-spin echo (TSE images, axial T1-weighted and contrast enhanced T1-weighted gradient echo (fast field echo, FFE and sagittal true Fast Imaging with Steady state Precession (true-FISP images. Application of contrast agent was performed via tail vein-catheter and confirmed by evaluation of the altered longitudinal relaxation T1 time before and after application. Through technical adaptation and optimization we could detect murine liver lesions with a minimum diameter of approximately 2 mm and provided histopathological evidence that these MR findings correspond to hepatocellular carcinoma. Tumor growth was repeatedly measured using sequential MRI with intervals of 5 weeks and subsequent volumetric analysis facilitating direct comparison of tumor progression between individual animals. We finally demonstrated that our protocol is also applicable in the widely- used chemical model of N-nitrosodiethylamine-induced hepatocarcinogenesis. Conclusion Our protocol allows the non-invasive, early detection of HCC and the subsequent continuous monitoring of liver tumorgenesis in transgenic mice thereby facilitating future investigations of transgenic tumor mouse models of the liver.

  16. Optical communications. V - Light emitting diodes /LED/

    Science.gov (United States)

    Best, S. W.

    1980-10-01

    The process of assembling diode chips is discussed, along with their application in optical communications. Metal plating is performed with an evaporation technique using primarily AuGe on the back side and Al or AuZn on the front side. The assembling of LED-chips with metal casings is illustrated. The chip is mounted on a flat bottom plate and electrical contact is established by means of an alloying or adhesion procedure. A glass fiber can be attached to the diode and then fitted with a casing, or the diode can be assembled with a metal cap and a lense, or with an open cap that is sealed with a clear synthetic resin plastic. The typical emission spectra of an LED and a semiconductor laser are compared. Limitations in the operation of an LED in a photoconductor are examined, taking into account spectral line width and radiated power criteria.

  17. Fractal properties of LED avalanche breakdown

    Directory of Open Access Journals (Sweden)

    Antonina S. Shashkina

    2016-12-01

    Full Text Available The conventional model of the processes occurring in the course of a p–n-junction's partial avalanche breakdown has been analyzed in this paper. Microplasma noise spectra of industrially produced LEDs were compared with those predicted by the model. It was established that the data obtained experimentally on reverse-biased LEDs could not be described in terms of this model. The degree to which the fractal properties were pronounced was shown to be variable by changing the reverse voltage. The discovered fractal properties of microplasma noise can serve as the basis for further studies which are bound to explain the breakdown characteristics of real LEDs and to correct the conventional model of p–n-junction's avalanche breakdown.

  18. Modeling the radiation pattern of LEDs.

    Science.gov (United States)

    Moreno, Ivan; Sun, Ching-Cherng

    2008-02-01

    Light-emitting diodes (LEDs) come in many varieties and with a wide range of radiation patterns. We propose a general, simple but accurate analytic representation for the radiation pattern of the light emitted from an LED. To accurately render both the angular intensity distribution and the irradiance spatial pattern, a simple phenomenological model takes into account the emitting surfaces (chip, chip array, or phosphor surface), and the light redirected by both the reflecting cup and the encapsulating lens. Mathematically, the pattern is described as the sum of a maximum of two or three Gaussian or cosine-power functions. The resulting equation is widely applicable for any kind of LED of practical interest. We accurately model a wide variety of radiation patterns from several world-class manufacturers.

  19. LED Device Illuminates New Path to Healing

    Science.gov (United States)

    2008-01-01

    Among NASA s research goals is increased understanding of factors affecting plant growth, including the effects of microgravity. Impeding such studies, traditional light sources used to grow plants on Earth are difficult to adapt to space flight, as they require considerable amounts of power and produce relatively large amounts of heat. As such, an optimized experimental system requires much less energy and reduces temperature variance without negatively affecting plant growth results. Ronald W. Ignatius, founder and chairman of the board at Quantum Devices Inc. (QDI), of Barneveld, Wisconsin, proposed using light-emitting diodes (LEDs) as the photon source for plant growth experiments in space. This proposition was made at a meeting held by the Wisconsin Center for Space Automation and Robotics, a NASA-sponsored research center that facilitates the commercialization of robotics, automation, and other advanced technologies. The Wisconsin group teamed with QDI to determine whether an LED system could provide the necessary wavelengths and intensities for photosynthesis, and the resultant system proved successful. The center then produced the Astroculture3, a plant growth chamber that successfully incorporated this LED light source, which has now flown on several space shuttle missions. NASA subsequently identified another need that could be addressed with the use of LEDs: astronaut health. A central concern in astronaut health is maintaining healthy growth of cells, including preventing bone and muscle loss and boosting the body s ability to heal wounds all adversely affected by prolonged weightlessness. Thus, having determined that LEDs can be used to grow plants in space, NASA decided to investigate whether LEDs might be used for photobiomodulation therapy (PBMT).

  20. High-power LEDs for plant cultivation

    Science.gov (United States)

    Tamulaitis, Gintautas; Duchovskis, Pavelas; Bliznikas, Zenius; Breive, Kestutis; Ulinskaite, Raimonda; Brazaityte, Ausra; Novickovas, Algirdas; Zukauskas, Arturas; Shur, Michael S.

    2004-10-01

    We report on high-power solid-state lighting facility for cultivation of greenhouse vegetables and on the results of the study of control of photosynthetic activity and growth morphology of radish and lettuce imposed by variation of the spectral composition of illumination. Experimental lighting modules (useful area of 0.22 m2) were designed based on 4 types of high-power light-emitting diodes (LEDs) with emission peaked in red at the wavelengths of 660 nm and 640 nm (predominantly absorbed by chlorophyll a and b for photosynthesis, respectively), in blue at 455 nm (phototropic function), and in far-red at 735 nm (important for photomorphology). Morphological characteristics, chlorophyll and phytohormone concentrations in radish and lettuce grown in phytotron chambers under lighting with different spectral composition of the LED-based illuminator and under illumination by high pressure sodium lamps with an equivalent photosynthetic photon flux density were compared. A well-balanced solid-state lighting was found to enhance production of green mass and to ensure healthy morphogenesis of plants compared to those grown using conventional lighting. We observed that the plant morphology and concentrations of morphologically active phytohormones is strongly affected by the spectral composition of light in the red region. Commercial application of the LED-based illumination for large-scale plant cultivation is discussed. This technology is favorable from the point of view of energy consumption, controllable growth, and food safety but is hindered by high cost of the LEDs. Large scale manufacturing of high-power red AlInGaP-based LEDs emitting at 650 nm and a further decrease of the photon price for the LEDs emitting in the vicinity of the absorption peak of chlorophylls have to be achieved to promote horticulture applications.

  1. LED module with high index lens

    Energy Technology Data Exchange (ETDEWEB)

    Bierhuizen, Serge J.; Wang, Nanze Patrick; Eng, Gregory W.; Sun, Decai; Wei, Yajun

    2016-07-05

    An array of housings with housing bodies and lenses is molded, or an array of housing bodies is molded and bonded with lenses to form an array of housings with housing bodies and lenses. Light-emitting diodes (LEDs) are attached to the housings in the array. An array of metal pads may be bonded to the back of the array or insert molded with the housing array to form bond pads on the back of the housings. The array is singulated to form individual LED modules.

  2. Embedded systems for controlling LED matrix displays

    Science.gov (United States)

    Marghescu, Cristina; Drumea, Andrei

    2016-12-01

    LED matrix displays are a common presence in everyday life - they can be found in trains, buses, tramways, office information tables or outdoor media. The structure of the display unit is similar for all these devices, a matrix of light emitting diodes coupled between row and column lines, but there are many options for the display controller that switches these lines. Present paper analyzes different types of embedded systems that can control the LED matrix, based on single board computers, on microcontrollers with different peripheral devices or with programmable logic devices like field programmable gate arrays with implemented soft processor cores. Scalability, easiness of implementation and costs are analyzed for all proposed solutions.

  3. Design of an Oximeter Based on LED-LED Configuration and FPGA Technology

    Directory of Open Access Journals (Sweden)

    Radovan Stojanovic

    2013-01-01

    Full Text Available A fully digital photoplethysmographic (PPG sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (SpO2. The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (SpO2. N-LEDs configuration is proposed for multichannel SpO2 measurements. The approach resulted in better spectral sensitivity, increased and adjustable resolution, reduced noise, small size, low cost and low power consumption.

  4. Modeling of spectral characteristics of blue LEDs

    DEFF Research Database (Denmark)

    Thorseth, Anders

    2010-01-01

    are expected to vary with current and junction temperature. Commercial high power blue LEDs were measured with respect to spectral distribution and chromaticity and the result was compared with the model predictions. We have found that the models predict significantly different results with respect...

  5. Preliminary investigations of piezoelectric based LED luminary

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Andersen, Michael A. E.; Meyer, Kaspar Sinding

    2011-01-01

    This paper presents a preliminary study of PT (Piezoelectric Transformer) based SMPS’s (Switch Mode Power Supplies) for LED luminary. The unique properties of PTs (efficiency, power density and EMI) make them highly suitable for this application. Power stage topologies, rectifiers circuits, modul...

  6. LED Lighting in a Performing Arts Building

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N. J.; Kaye, S. M. [Univ. of Florida, Gainesville, FL (United States); Coleman, P. M. [Univ. of Florida, Gainesville, FL (United States); Wilkerson, A. M.; Perrin, T. E.; Sullivan, G. P. [Efficiency Solutions, Inc., Richland, WA (United States)

    2014-07-31

    At the University of Florida in Gainesville, the DOE Solid-State Lighting GATEWAY program evaluated LED architectural and theatrical lighting in four academic/performance-related spaces within the Nadine McGuire Theatre + Dance Pavilion. Due to a wise choice of products and luminaire light distributions, the change brought significant quality improvements including improved controllability and color.

  7. Silicon LEDs in FinFET technology

    NARCIS (Netherlands)

    Piccolo, G.; Kuindersma, P.I.; Ragnarsson, L-A.; Hueting, R.J.E.; Collaert, N.; Schmitz, J.

    2014-01-01

    We present what to our best knowledge is the first forward operating silicon light-emitting diode (LED) in fin-FET technology. The results show near-infrared (NIR) emission around 1100 nm caused by band-to-band light emission in the silicon which is uniformly distributed across the lowly doped activ

  8. Modifying effects of Soybean and Nigella Sativa against Experimental Hepato-carcinogenesis induced By Nitrosamine Precursor in Rats Histopathological and electron microscopically study

    Directory of Open Access Journals (Sweden)

    Hanaa F. Waer, **Abdel Baset EL Asser, ***Hamdy A. Ibrahim

    2005-03-01

    Full Text Available Cancer has become an important topic in medicine since it is a major cause of death in the developing countries and it is now only secondary to that of myocardial infraction. Nitrosamines precursors are known to be carcinogenic to humans, in various organs at relatively low levels of exposure. It induces benign and malignant tumors especially liver tumors following its administration by various routes, including ingestion and inhalation. Humans may be exposed to Nitrosamines through the ingestion of food that contains it, such as cured meat products, and smoked fish. Other exposures to Nitrosamines may be from drinking contaminated water and from breathing cigarette smoke and contaminated ambient air. Individual are most likely to be exposed to Nitrosamines in occupational settings such as in the rubber, tannery, fish processing, dyes, and surfactant industries. The prevalence of liver tumors throughout the world makes in imperative to seek chemo preventive agents. Vegetables, natural products of plant origin and numerous non-nutritive dietary constituents have been shown to play a salutary role in cancer chemoprevention. The present study aims to evaluate the chemo preventive efficacy of soy bean and Nigella sativa on hepato-carcinogenesis induced by dibuty1 nitrosamine (DEN. It could be observed that both soy bean and Nigella sativa have a good effect of amelioration against liver hepatoma induced by nitrosamine. Soy bean more or less showed more prerogative effect than Nigella 9 and 12 months after administration.

  9. Effects of gomisin A on the promotor action and serum bile acid concentration in hepatocarcinogenesis induced by 3'-methyl-4-dimethylamino-azobenzene.

    Science.gov (United States)

    Miyamoto, K; Hiramatsu, K; Ohtaki, Y; Kanitani, M; Nomura, M; Aburada, M

    1995-10-01

    The effects of gomisin A, a lignan component of Schizandra fruits, on the promotion stage of hepatocarcinogenesis initiated by 3'-methyl-4-dimethylamino-azobenzene (3'-MeDAB) in male Donryu rats were investigated. When different types of tumor promotors, phenobarbital (PB) and deoxycholic acid (DCA), were administered for 5 weeks after initiation by 3'-MeDAB, preneoplastic alterations in the liver, determined by glutathione S-transferase placental form (GST-P), were markedly increased. Gomisin A significantly inhibited the increase in number and size of GST-P positive foci, regardless of the promotor. This lignan inhibited the increase in serum bile acid concentration by administration of DCA, but hardly influenced the serum bile acids in the PB-combined group. These results suggest that the inhibitory effect of gomisin A on the promotive action of DCA is based on improving bile acid metabolism, but regarding the action of PB, the effect could not be elucidated from the metabolism of bile acids.

  10. Multistep hepatocarcinogenesis from a dysplastic nodule to well-differentiated hepatocellular carcinoma in a patient with alcohol-related liver cirrhosis

    Institute of Scientific and Technical Information of China (English)

    Soo Ryang Kim; Yoshitake Hayashi; Hirotsugu Ikawa; Kenji Ando; Keiji Mita; Shuichi Fuki; Michiie Sakamoto; Yoshihiro Kanbara; Toshiyuki Matsuoka; Masatoshi Kudo

    2007-01-01

    We describe a rare case of the transformation of a dysplastic nodule into well-differentiated hepatocellular carcinoma (HCC) in a 56-year-old man with alcoholrelated liver cirrhosis. Ultrasound (US) disclosed a 10 mm hypoechoic nodule and contrast enhanced US revealed a hypovascular nodule, both in segment seven.US-guided biopsy revealed a high-grade dysplastic nodule characterized by enhanced cellularity with a high N/C ratio, increased cytoplasmic eosinophilia,and slight cell atypia. One year later, the US pattern of the nodule changed from hypoechoic to hyperechoic without any change in size or hypovascularity. US-guided biopsy revealed well-differentiated HCC of the same features as shown in the first biopsy, but with additional pseudoglandular formation and moderate cell atypia.Moreover, immunohistochemical staining of cyclaseassociated protein 2, a new molecular marker of well-differentiated HCC, turned positive. This is the first case of multistep hepatocarcinogenesis from a dysplastic nodule to well-differentiated HCC within one year in alcohol-related liver cirrhosis.

  11. Low-Cost Illumination-Grade LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Epler, John [Philips Lumileds Lighting Company LLC, San Jose, CA (United States)

    2013-08-31

    Solid State Lighting is a cost-effective, energy-conserving technology serving a rapidly expand- ing multi-billion dollar market. This program was designed to accelerate this lighting revolution by reducing the manufacturing cost of Illumination-Grade LEDs. The technical strategy was to investigate growth substrate alternatives to standard planar sapphire, select the most effective and compatible option, and demonstrate a significant increase in Lumen/$ with a marketable LED. The most obvious alternate substrate, silicon, was extensively studied in the first two years of the program. The superior thermal and mechanical properties of Si were expected to improve wavelength uniformity and hence color yield in the manufacture of high-power illumination- grade LEDs. However, improvements in efficiency and epitaxy uniformity on standard c-plane sapphire diminished the advantages of switching to Si. Furthermore, the cost of sapphire decreased significantly and the cost of processing Si devices using our thin film process was higher than expected. We concluded that GaN on Si was a viable technology but not a practical option for Philips Lumileds. Therefore in 2012 and 2013, we sought and received amendments which broadened the scope to include other substrates and extended the time of execution. Proprietary engineered substrates, off-axis (non-c-plane) sapphire, and c-plane patterned sapphire substrates (PSS) were all investigated in the final 18 months of this program. Excellent epitaxy quality was achieved on all three candidates; however we eliminated engineered substrates and non-c-plane sapphire because of their higher combined cost of substrate, device fabrication and packaging. Ultimately, by fabricating a flip-chip (FC) LED based upon c-plane PSS we attained a 42% reduction in LED manufacturing cost relative to our LUXEON Rebel product (Q1-2012). Combined with a flux gain from 85 to 102 Lm, the LUXEON Q delivered a 210% increase in Lm/$ over this time period. The

  12. Sustainable LED Fluorescent Light Replacement Technology

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2011-09-30

    Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life: Environmental Impact Review – Designs are comparable

  13. Fluorescent protein integrated white LEDs for displays

    Science.gov (United States)

    Press, Daniel Aaron; Melikov, Rustamzhon; Conkar, Deniz; Nur Firat-Karalar, Elif; Nizamoglu, Sedat

    2016-11-01

    The usage time of displays (e.g., TVs, mobile phones, etc) is in general shorter than their functional life time, which worsens the electronic waste (e-waste) problem around the world. The integration of biomaterials into electronics can help to reduce the e-waste problem. In this study, we demonstrate fluorescent protein integrated white LEDs to use as a backlight source for liquid crystal (LC) displays for the first time. We express and purify enhanced green fluorescent protein (eGFP) and monomeric Cherry protein (mCherry), and afterward we integrate these proteins as a wavelength-converter on a blue LED chip. The protein-integrated backlight exhibits a high luminous efficacy of 248 lm/Wopt and the area of the gamut covers 80% of the NTSC color gamut. The resultant colors and objects in the image on the display can be well observed and distinguished. Therefore, fluorescent proteins show promise for display applications.

  14. Cooling of led module by various radiators

    Directory of Open Access Journals (Sweden)

    Naumova A. M.

    2015-12-01

    Full Text Available Given article presents the results of an experimental comparison of three radiators which are: pressed radiator made of aluminum plate (basic variant, radiator made of copper wire, and copper/water pulsating heat pipe. The radiators are intended to take off heat from the LED module with the power capacity of 10,55 W. It is established that under natural convection all three radiators can keep temperature level of the circuit board module less than 64 C that lies within the operating range. In comparison with basic variant the use of the copper wire radiator allows lowering of the temperature in the LED module center on 3.9 C, and the same value for the pulsating heat pipe is 7.1 C.

  15. EVALUATING THE CULTURE-LED REGENERATION

    Directory of Open Access Journals (Sweden)

    D'Angelo Francesca

    2010-12-01

    Full Text Available The aim of the paper is to propose a new approach to urban planning, evaluating the culture-led regeneration processes. In the last few years, the cultural turn in urban planning played a central role in the urban studies. In this way we try to elaborate a more robust perspective interpreting the complex phenomenology emerging from the culture-led regeneration processes. Within the concept of complexity we discuss about the metabolic process that are the processes necessary to transform energy, material and information in goods and service functional to the complex urban system life. The approach that will be employed is the MuSIASEM that is based on several novel concept and an innovative methods never applied in this research field.

  16. Notes on LED Installations in Street Illumination

    Directory of Open Access Journals (Sweden)

    Elisabeta Spunei

    2014-09-01

    Full Text Available The paper presents a study made on choosing LED street lighting installations, such that the quality requirements for exterior artificial lighting are fulfilled. We analyze two types of LED street lighting installations from a technical point of view, together with lighting level and brightness values obtained during the measurements. Following on the field measurements, the lighting quality parameters are calculated, and, for the lighting installation with the best performance, optimal mounting suggestions are made. The optimal quality parameters are calculated by simulations using the Dialux software. The same software and the same light sources we also compute an optimal street lighting by determining the size of the installation that provides the best lighting parameter values.

  17. Imprint lithography advances in LED manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Robert; Doyle, Gary; Jones, Chris; LaBrake, Dwayne; Miller, Mike [Molecular Imprints Inc., 1807 West Braker Lane, Building C-11, Austin, TX 78758 (United States)

    2007-07-01

    Imprint lithography is a promising cost effect alternative to e-beam and optical lithography for producing photonic crystals and other nano-scale light extraction and beam directing elements for LEDs; however, there are several challenges that must be overcome before imprint lithography can be applied to typical LED substrates. This paper reviews progress made at Molecular Imprints Inc. (MII) in imprinting representative 3{sup ''} GaN on Sapphire substrates including methods for dealing with substrate non-flatness, multi-die imprint, and imprinting on warped and bowed substrates. The results of imprinting over typical GaN on Sapphire topography and common defects such as fall-on particles and EPI defects is presented along with results on GaN wafers optimized for imprint lithography. Whole wafer thin template replication techniques are also discussed. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Nurse-led management of contraceptive services.

    Science.gov (United States)

    Wilson, Emma

    2014-07-01

    This article discusses the role of the practice nurse (PN) in the provision of health assessment for contraceptive choices. PNs who have an extended role as an independent nurse prescriber must demonstrate the principles of safe prescribing practice, with appropriate and informed assessment of the patient's needs and risk within the limited time of a general practice appointment. With continued professional development, PNs are well placed to provide comprehensive, independent nurse-led contraceptive services.

  19. Study and Design of LED Lighting Systems

    Directory of Open Access Journals (Sweden)

    Li Cheng

    2013-06-01

    Full Text Available In this study, the optical characteristics, thermal characteristics, electrical characteristics of the LED device are studied. After analysis of the significance of the optical model, we establish the model of the LED light source using optical simulation software to analyze the impact of modeling four factors and law, based on ray tracing model intensity distribution with the manufacturers. On this basis, we expand the LED secondary optical design, namely, increasing of LDE method to the light level. After comparing different forms of non-imaging optical components, combined with the actual situation, the final choice is the system composed of rotating parabolic reflector with LDE. Besides, the reflected changing the relative position of the body and LDE space lead to the normal light intensity of the entire system appearing two peaks, but their causes are different. In addition, the method of combining theoretical analysis and computer simulations to study the distribution of LDE array illumination is utilized. Formula on the illumination distribution in the LDB array to a plane parallel thereto is deduced, which is verified by computer simulation and agrees well with it. A quantitative study of the factors affecting the road surface illuminance distribution is made on the basis of previous study, combined with the actual road lighting works. These factors are: LDE array form, the number of LED, spacing between LDE, LDE interval between the street lamps. The derived entire road illumination distribution formula and the corresponding curve gives a basic method for the analysis of such practical problems related outcomes for the LDE illumination optical system design and research basis.

  20. Export-led Growth Hypothesis: Turkey Application

    Directory of Open Access Journals (Sweden)

    İsmail KÜÇÜKAKSOY

    2015-12-01

    Full Text Available This paper aims to investigate validity of “Export-led Growth Hypothesis” for Turkey using quarterly data in period from 2003:Q1 to 2015:Q1. Hypothesis argues that there is causality relationship from real export to real Gross Domestic Product (GDP. Johansen cointegration test, Gregory-Hansen cointegration test, Toda-Yamamoto causality test, Fully Modified Ordinary Least Squares (FMOLS, Canonical cointegrating regression (CCR and Dynamic ordinary least squares (DOLS methods were used in this study. Findings can be summarized as follows: a According to Johansen cointegration test there is no relationship among variables in the long-run whereas Gregory-Hansen cointegration test has determined relationship in the long-run; b According to Toda-Yamamoto causality test there is bidirectional causality between real export and real GDP. This finding proves the validity of “Export-led Growth Hypothesis” for Turkey; c According to FMOLS, CCR, DOLS methods a 1% increase in the real export increases the real GDP by 1.5195%, 1.5552%, 1.3171% respectively in the long-run. These methods prove the validity of “Export-led Growth Hypothesis” for Turkey.

  1. Curing efficiency of modern LED units.

    Science.gov (United States)

    Rencz, Adam; Hickel, Reinhard; Ilie, Nicoleta

    2012-02-01

    Recent reports claim that modern light-emitting diode (LED) curing units improve curing efficiency by increasing the units' irradiance. In this context also, short polymerisation times up to 5 s are proposed. The aim of this study was to examine whether there are differences in the curing efficiency of modern LED curing units by assessing their effect on two different composite materials and by varying the irradiation time. A nano- and a micro-hybrid resin-based composite (RBC) were polymerised for 5, 10 and 20 s with three commercial and a Prototype LED unit (Elipar™ S10). Cylindrical specimens (6 mm in depth, 4 mm in diameter) were prepared in three increments, each 2-mm thick, and were consecutively cured. Degree of cure was measured for 20 min in real time at the bottom of the samples, starting with the photoinitiation. The micro-mechanical properties (modulus of elasticity, E and Vickers hardness, HV) were measured as a function of depth, in 100-μm steps, on the above described samples stored in distilled water for 24 h at 37°C. Data were analysed with multivariate ANOVA followed by Tukey's test, t test and partial eta-squared statistics. In descending order of the strength of their effect, the type of RBC, depth, polymerisation time and curing unit were significant factors affecting the micro-mechanical parameters (p surface, a minimum of 20 s of irradiation is necessary for an adequate polymerisation 2 mm beyond the surface.

  2. Light out-coupling from LEDs by means of metal nanoparticles; Lichtauskopplung aus LEDs mittels Metallnanoteilchen

    Energy Technology Data Exchange (ETDEWEB)

    Goehler, Tino

    2010-12-17

    The external quantum efficiency of light-emitting diodes (LEDs) based on Al- GaAs/InGaAlP is limited by total internal reflection because of the high refractive index (typically between 3 and 4) of the semiconductor. Metal nanoparticles (MNP) deposited on the surface of the LED can be used as dipole scatterers in order to enhance the emission of the LED. In this thesis, first, single gold nanoparticles of various sizes deposited on such an LED were investigated. A clear enhancement is detected as long as the dipole plasmon resonance of the particle is at a shorter wavelength than the LED emission. If the plasmon resonance coincides with the LED emission or is at a larger wavelength, the enhancement turns into suppression. Numerical simulations indicate that this latter effect is mainly caused by the particle quadrupole resonance producing extra absorption. Arrays of MNPs can be produced by a special mask technique called ''Fischer pattern nanolithography'' and manipulated in shape and size by additional steps. Originally, the MNPs produced by this technique are triangular in shape and turn out to suppress the LED emission. After transformation of the particles to spheres, a clear enhancement was detected. Light that would otherwise remain trapped inside the substrate is coupled out by resonant plasmonic scattering. Investigations on analogous structures on a transparent high-index material (GaP) indicate a stronger coupling between the particles than expected on the basis of literature data. (orig.)

  3. Phosphor-in-glass for high-powered remote-type white AC-LED.

    Science.gov (United States)

    Lin, Hang; Wang, Bo; Xu, Ju; Zhang, Rui; Chen, Hui; Yu, Yunlong; Wang, Yuansheng

    2014-12-10

    The high-powered alternating current (AC) light-emitting diode (LED) (AC-LED), featuring low cost, high energy utilization efficiency, and long service life, will become a new economic growth point in the field of semiconductor lighting. However, flicker of AC-LED in the AC cycles is not healthy for human eyes, and therefore need to be restrained. Herein we report an innovation of persistent "phosphor-in-glass" (PiG) for the remote-type AC-LED, whose afterglow can be efficiently activated by the blue light. It is experimentally demonstrated that the afterglow decay of PiG in the microsecond range can partly compensate the AC time gap. Moreover, the substitution of inorganic glass for organic resins or silicones as the encapsulants would bring out several technological benefits to AC-LED, such as good heat-dissipation, low glare, and excellent physical/chemical stability.

  4. Perceived learning effectiveness of a course Facebook page: teacher-led versus student-led approach

    Directory of Open Access Journals (Sweden)

    Tugba Orten Tugrul

    2017-01-01

    Full Text Available This research aims to compare the perceived effectiveness of teacher -led and student-led content management approaches embraced in a course Facebook page designed to enhance traditional classroom learning. Eighty-five undergraduate marketing course students voluntarily completed a questionnaire composed of two parts; a depiction of a course Facebook page where both teacher and students can share instructional contents, and questions about perceived learning effectiveness. The findings indicate that students have more favorable evaluations of a student-led approach in sharing instructional contents on a course Facebook Page than a teacher-led approach. Additionally, it is shown that instructional contents posted by both teacher and students enhance the overall learning effectiveness of a course Facebook page incorporated into a traditional classroom teaching.

  5. LED to LED communication with WDM concept for flash light of Mobile phones

    Directory of Open Access Journals (Sweden)

    Devendra J Varanva

    2013-08-01

    Full Text Available After observing recent developments in Free Space Optical Communication especially Visible Light Communication, It is clear that LED is main component as a source. LED being solid state device makes endless list of possibilities. But here we will get through its ability to sense light as well, and use of Wavelength Division Multiplexing (WDM in mobile flash is also suggested, this opens door to many applications.

  6. Assessing the colour quality of LED sources

    DEFF Research Database (Denmark)

    Jost-Boissard, S.; Avouac, P.; Fontoynont, Marc

    2015-01-01

    The CIE General Colour Rendering Index is currently the criterion used to describe and measure the colour-rendering properties of light sources. But over the past years, there has been increasing evidence of its limitations particularly its ability to predict the perceived colour quality of light...... sources and especially some LEDs. In this paper, several aspects of perceived colour quality are investigated using a side-by-side paired comparison method, and the following criteria: naturalness of fruits and vegetables, colourfulness of the Macbeth Color Checker chart, visual appreciation...

  7. LED Context Lighting System in Residential Areas

    Directory of Open Access Journals (Sweden)

    Sook-Youn Kwon

    2014-01-01

    Full Text Available As issues of environment and energy draw keen interest around the globe due to such problems as global warming and the energy crisis, LED with high optical efficiency is brought to the fore as the next generation lighting. In addition, as the national income level gets higher and life expectancy is extended, interest in the enhancement of life quality is increasing. Accordingly, the trend of lightings is changing from mere adjustment of light intensity to system lighting in order to enhance the quality of one’s life as well as reduce energy consumption. Thus, this study aims to design LED context lighting system that automatically recognizes the location and acts of a user in residential areas and creates an appropriate lighting environment. The proposed system designed in this study includes three types of processing: first, the creation of a lighting environment index suitable for the user’s surroundings and lighting control scenarios and second, it measures and analyzes the optical characteristics that change depending on the dimming control of lighting and applies them to the index. Lastly, it adopts PIR, piezoelectric, and power sensor to grasp the location and acts of the user and create a lighting environment suitable for the current context.

  8. LED context lighting system in residential areas.

    Science.gov (United States)

    Kwon, Sook-Youn; Im, Kyoung-Mi; Lim, Jae-Hyun

    2014-01-01

    As issues of environment and energy draw keen interest around the globe due to such problems as global warming and the energy crisis, LED with high optical efficiency is brought to the fore as the next generation lighting. In addition, as the national income level gets higher and life expectancy is extended, interest in the enhancement of life quality is increasing. Accordingly, the trend of lightings is changing from mere adjustment of light intensity to system lighting in order to enhance the quality of one's life as well as reduce energy consumption. Thus, this study aims to design LED context lighting system that automatically recognizes the location and acts of a user in residential areas and creates an appropriate lighting environment. The proposed system designed in this study includes three types of processing: first, the creation of a lighting environment index suitable for the user's surroundings and lighting control scenarios and second, it measures and analyzes the optical characteristics that change depending on the dimming control of lighting and applies them to the index. Lastly, it adopts PIR, piezoelectric, and power sensor to grasp the location and acts of the user and create a lighting environment suitable for the current context.

  9. An investigation on LED customer’ behavior

    Directory of Open Access Journals (Sweden)

    Samaneh Sadat Khoramgah

    2013-03-01

    Full Text Available The recent advances in technology have created a challenge for customer on purchasing electronic devises since the cycle of media production such as TV, Mobile devices, etc. are getting short and people need to replace them by new products. The recent emerge of Light Emitting Diode (LED television has attracted many people and there is a concern to study the impact of important factors on customer behavior in this business. This paper presents an empirical study to study the effects of six variables including customer perception, motivation, cognitive learning, attitude, information and price on customer behavior for LED televisions produced by an Iranian firm in Tehran, Iran. The study designs a questionnaire consists of 27 questions and distributes it among some people who are potential customers of this product. We use multiple regression analysis to study the behavior of different factors on customer behavior. The results of our survey indicate that cognitive learning had the most influencing impact (0.22 on customer behavior followed by price (0.219, motivation (0.203, attitude (0.193, information (0.183 and perception (0.145.

  10. Improved performance of UV-LED by p-AlGaN with graded composition

    KAUST Repository

    Yan, Jianchang

    2010-11-02

    AlGaN-based ultraviolet light emitting diodes (UV-LEDs) on AlN/sapphire template were grown by metal organic chemical vapour deposition. The AlN template was characterized by atomic force microscopy and high resolution X-ray diffraction. Atomic force microscopy image shows that the AlN surface is very flat, while high resolution X-ray diffraction results prove the good crystalline quality of the AlN template. A novel structure UV-LED which has several p-AlGaN layers with graded composition is compared with a common structure UV-LED which has a single p-Al0.5Ga0.5N layer. The forward bias voltage at 20 mA driving current for the novel structure UV-LED is nearly 3 V higher than that of the common structure UV-LED, however, the electroluminescence intensity of the former is over two times higher than that of the latter. The total quantum efficiency of the novel structure UV-LED is more than 50% higher than that of the common structure UV-LED. The improvement is considered to be the result of better holes injection efficiency in the novel structure UV-LED. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. EDITORIAL: Micro-pixellated LEDs for science and instrumentation

    Science.gov (United States)

    Dawson, Martin D.; Neil, Mark A. A.

    2008-05-01

    This Cluster Issue of Journal of Physics D: Applied Physics highlights micro-pixellated gallium nitride light-emitting diodes or `micro-LEDs', an emerging technology offering considerable attractions for a broad range of scientific and instrumentation applications. It showcases the results of a Research Councils UK (RCUK) Basic Technology Research programme (http://bt-onethousand.photonics.ac.uk), running from 2004-2008, which has drawn together a multi-disciplinary and multi-institutional research partnership to develop these devices and explore their potential. Images of LEDs Examples of GaN micro-pixel LEDs in operation. Images supplied courtesy of the Guest Editors. The partnership, of physicists, engineers and chemists drawn from the University of Strathclyde, Heriot-Watt University, the University of Sheffield and Imperial College London, has sought to move beyond the established mass-market uses of gallium nitride LEDs in illumination and lighting. Instead, it focuses on specialised solid-state micro-projection devices the size of a match-head, containing up to several thousand individually-addressable micro-pixel elements emitting light in the ultraviolet or visible regions of the spectrum. Such sources are pattern-programmable under computer control and can project into materials fixed or high-frame rate optical images or spatially-controllable patterns of nanosecond excitation pulses. These materials can be as diverse as biological cells and tissues, biopolymers, photoresists and organic semiconductors, leading to new developments in optical microscopy, bio-sensing and chemical sensing, mask-free lithography and direct writing, and organic electronics. Particular areas of interest are multi-modal microscopy, integrated forms of organic semiconductor lasers, lab-on-a-chip, GaN/Si optoelectronics and hybrid inorganic/organic semiconductor structures. This Cluster Issue contains four invited papers and ten contributed papers. The invited papers serve to set

  12. Fumonisin contamination of a corn sample associated with the induction of hepatocarcinogenesis in rats-role of dietary deficiencies.

    Science.gov (United States)

    Gelderblom, W C A; Rheeder, J P; Leggott, N; Stockenstrom, S; Humphreys, J; Shephard, G S; Marasas, W F O

    2004-03-01

    A corn sample associated with a field outbreak of equine leukoencephalomalacia in Pennsylvania, USA, during 1983/1984 and induced hepatotoxic and hepatocarcinogenic effects when fed to male Fischer rats was analyzed mycologically and chemically for the presence of fumonisins (FB), hydrolysed FB derivatives and aflatoxins (AFB). Fusarium verticillioides was found to be the predominant fungal contaminant in the corn sample but Aspergillus flavus was also present. Trace amounts (0.1 microg/kg) of AFB(1) and AFB(2) and a total FB level of 33.5 mg/kg (FB(1):FB(2):FB(3) ratio of 9:2.3:1) were found. No hydrolysed FB derivatives or AFG(1) and AFG(2) were detected. Based on the chemical stability of the fumonisins in different corn cultures of F. verticillioides kept at 4 degrees C over a period of 13-20 years, a level of approximately 55 mg/kg of total FB is estimated in the original corn sample. A possible role of certain dietary constituents such as the high protein content and deficiencies in certain micronutrients is evaluated to address differences in the organ-specific toxicity of FB(1) in rats using commercial, semi-purified, purified and corn-only diets.

  13. EDITORIAL: LED light sources (light for the future) LED light sources (light for the future)

    Science.gov (United States)

    Grandjean, N.

    2010-09-01

    Generating white light from electricity with maximum efficacy has been a long quest since the first incandescent lamp was invented by Edison at the end of the 19th century. Nowadays, semiconductors are making reality the holy grail of converting electrons into photons with 100% efficiency and with colours that can be mixed for white light illumination. The revolution in solid-state lighting (SSL) dates to 1994 when Nakamura reported the first high-brightness blue LED based on GaN semiconductors. Then, white light was produced by simply combining a blue dye with a yellow phosphor. After more than a decade of intensive research the performance of white LEDs is quite impressive, beating by far the luminous efficacy of compact fluorescent lamps. We are likely close to replacing our current lighting devices by SSL lamps. However, there are still technological and fabrication cost issues that could delay large market penetration of white LEDs. Interestingly, SSL may create novel ways of using light that could potentially limit electricity saving. Whatever the impact of SSL, it will be significant on our daily life. The purpose of this special cluster issue is to produce a snapshot of the current situation of SSL from different viewing angles. In an introductory paper, Tsao and co-workers from Sandia National Laboratories, present an energy-economics perspective of SSL considering societal changes and SSL technology evolution. In a second article, Narukawa et al working at Nichia Corporation—the pioneer and still the leading company in SSL—describe the state of the art of current research products. They demonstrate record performance with white LEDs exhibiting luminous efficacy of 183 lm W-1 at high-current injection. Then, a series of topical papers discuss in detail various aspects of the physics and technology of white LEDs Carrier localization in InGaN quantum wells has been considered the key to white LEDs' success despite the huge density of defects. A

  14. Switched-capacitor isolated LED driver

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, Seth R.; Kline, Mitchell

    2016-03-22

    A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V.sub.DC. A regulator section, operating on V.sub.DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

  15. LED--panacea or marketing hype?

    Science.gov (United States)

    Baillie, Jonathan

    2012-02-01

    With energy efficiency and carbon reduction, and the importance of a relaxing, therapeutic patient environment, ever more in the spotlight, LED lighting's proponents claim the technology offers healthcare estates personnel many of the answers on both fronts. However some observers believe its benefits are being over-sold, often to the detriment of other high-performing types of more 'conventional lighting', and to a sometimes uninitiated audience too easily swayed by slick sales patter. HEJ editor Jonathan Baillie spoke to one highly experienced lighting professional, Nicholas Bukorović, a former employee of Thorn, Cooper, and Thorlux Lighting, and the principal author of the last CIBSE/Society of Light and Lighting (SLL) Guide LG2 on healthcare lighting, to seek some expert illumination.

  16. Intranodular signal intensity analysis of hypovascular high-risk borderline lesions of HCC that illustrate multi-step hepatocarcinogenesis within the nodule on Gd–EOB–DTPA-enhanced MRI

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Satoshi, E-mail: satoshik@staff.kanazawa-u.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan); Matsui, Osamu, E-mail: matsuio@med.kanazawa-u.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan); Gabata, Toshifumi, E-mail: gabata@med.kanazawa-u.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan); Koda, Wataru, E-mail: wkoda@staff.kanazawa-u.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan); Minami, Tetsuya, E-mail: tminami@staff.kanazawa-u.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan); Ryu, Yasuji, E-mail: yryu-kanazawa@umin.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan); Kozaka, Kazuto, E-mail: k-kozaka@staff.kanazawa-u.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan); Kitao, Azusa, E-mail: azusa@med.kanazawa-u.ac.jp [Dept of Radiology, Kanazawa University School of Medicine, 13-1, Takara Machi, Kanazawa 920-8641 (Japan)

    2012-12-15

    Objectives: To analyze intranodular signal intensity pattern of hypovascular high-risk borderline lesions of HCC that illustrate multi-step hepatocarcinogenesis within the nodule on Gd–EOB–DTPA-enhanced MRI. Methods: A total of 73 nodules showing hypervascular foci in hypovascular high-risk borderline lesions identified by angiography-assisted CT were included in this study. The intranodular signal intensities of both the hypervascular foci and the hypovascular high-risk borderline lesions were evaluated on hepatobiliary-phase EOB-enhanced MRI obtained 20 min after intravenous injection of contrast media. Results: Among 59 hypervascular foci within hypointense hypovascular high-risk borderline lesions, 6 showed more hypointensity, 32 isointensity, and 21 hyperintensity compared to the surrounding hypointense, hypovascular portion of the nodules. Among 14 hypervascular foci within isointense hypovascular high-risk borderline lesions, 5 showed isointensity, and 9 hypointensity compared to the surrounding isointense hypovascular high-risk borderline lesions. No hypervascular foci showed hyperintensity compared to the surrounding isointense hypovascular high-risk borderline lesions. Conclusions: In most of the hypovascular high-risk borderline lesions containing hypervascular foci within the nodule, the signal intensity was decreased in hypervascular foci as compared with hypovascular high-risk borderline lesions and the surrounding background liver parenchyma. This supports the concept of signal intensity decrease during the dedifferentiation process in multistep hepatocarcinogenesis. However, around 30% of the nodules did not follow this rule, and hypervascular foci showed hyperintensity relative to the hypovascular high-risk borderline lesions.

  17. Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons.

    Directory of Open Access Journals (Sweden)

    Jens B Bosse

    Full Text Available Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs, however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution.

  18. LED 蓝光危害研究%Research of LED Blue Light Hazard

    Institute of Scientific and Technical Information of China (English)

    赵介军; 乔波; 过峰

    2015-01-01

    随着人们对于照明产品光生物效应的关注, LED照明产品的光生物辐射安全问题,尤其是视网膜蓝光危害已成为人们对于LED产品望而却步的一个重要原因。通过研究LED的蓝光危害,分析了LED蓝光危害产生的原因和可能对人体造成的伤害。并通过实验调研市场上LED照明产品的蓝光危害现状,阐述了如何正确的使用LED产品,从而有效避免蓝光辐射危害。%LED lighting products with its beneficial characteristics, such as energy saving, environmental protection, long life, small size, and etc, have gradually entered people’s life.People started to care about the photobiological effects of lighting products.The photobiological radiation safety of LED lighting products, especially the retinal blue light hazard has become an important reason why people do not choose LED products. This paper analyzed the reasons and their possible harms to the human body which may be caused by LED blue light hazard.And by performing research on current situation of LED lighting products blue light hazard in market, it described how to properly use LED products so as to effectively prevent blue light hazards.

  19. Conformal phosphor coating using pulsed spray to reduce color deviation of white LEDs.

    Science.gov (United States)

    Huang, Hsin-Tao; Tsai, Chuang-Chuang; Huang, Yi-Pai

    2010-06-21

    This work presents a novel "pulsed spray (PS)" process for the coating of yellow YAG:Ce(3+) phosphor on blue InGaN-based light emitting diodes (LEDs). To coat a phosphor layer of high quality on an LED chip surface, the PS approach is used and studied because of the uniform color distribution, providing a wide range of color temperatures. This PS coating approach applies phosphor by exploiting mechanical principles without risk of chemical pollution. Additionally, it can be applied to wire-bonded LEDs and an array of LED chips on a substrate to fabricate a large-area, planar illumination system of high optical quality, which is easy to manufacture.

  20. Color tunable monolithic InGaN/GaN LED having a multi-junction structure.

    Science.gov (United States)

    Kong, Duk-Jo; Kang, Chang-Mo; Lee, Jun-Yeob; Kim, James; Lee, Dong-Seon

    2016-03-21

    In this study, we have fabricated a blue-green color-tunable monolithic InGaN/GaN LED having a multi-junction structure with three terminals. The device has an n-p-n structure consisting of a green and a blue active region, i.e., an n-GaN / blue-MQW / p-GaN / green-MQW / n-GaN / Al2O3 structure with three terminals for independently controlling the two active regions. To realize this LED structure, a typical LED consisting of layers of n-GaN, blue MQW, and p-GaN is regrown on a conventional green LED by using a metal organic chemical vapor deposition (MOCVD) method. We explain detailed mechanisms of three operation modes which are the green, blue, and cyan mode. Moreover, we discuss optical properties of the device.

  1. Experiencing LED: Lighting: New Form and Experiential Qualities Emerging in Lighting Systems using LED

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Kristensen, Ole; Søndergaard, Karin

    2012-01-01

    The project investigates what new forms and qualities of light emerge from technologies such as LED, with a particular focus on basic form qualities and parameters. Existing linear functional understandings of the relation between light source, light flow, reflection and visibility is challenged ...... by relational understandings, where the materiality and visibility of the light emerge through mutual influences between several adaptive and transformative elements....

  2. Led Astray by Hemoglobin A1c

    Directory of Open Access Journals (Sweden)

    Jean Chen MD

    2016-01-01

    Full Text Available Hemoglobin A1c (A1c is used frequently to diagnose and treat diabetes mellitus. Therefore, it is important be aware of factors that may interfere with the accuracy of A1c measurements. This is a case of a rare hemoglobin variant that falsely elevated a nondiabetic patient’s A1c level and led to a misdiagnosis of diabetes. A 67-year-old male presented to endocrine clinic for further management after he was diagnosed with diabetes based on an elevated A1c of 10.7%, which is approximately equivalent to an average blood glucose of 260 mg/dL. Multiple repeat A1c levels remained >10%, but his home fasting and random glucose monitoring ranged from 92 to 130 mg/dL. Hemoglobin electrophoresis and subsequent genetic analysis diagnosed the patient with hemoglobin Wayne, a rare hemoglobin variant. This variant falsely elevates A1c levels when A1c is measured using cation-exchange high-performance liquid chromatography. When the boronate affinity method was applied instead, the patient’s A1c level was actually 4.7%. Though hemoglobin Wayne is clinically silent, this patient was erroneously diagnosed with diabetes and started on an antiglycemic medication. Due to this misdiagnosis, the patient was at risk of escalation in his “diabetes management” and hypoglycemia. Therefore, it is important that providers are aware of factors that may result in hemoglobin A1c inaccuracy including hemoglobin variants.

  3. Factors that led to the Walkerton tragedy.

    Science.gov (United States)

    Salvadori, Marina I; Sontrop, Jessica M; Garg, Amit X; Moist, Louise M; Suri, Rita S; Clark, William F

    2009-02-01

    In May 2000, bacterial contamination of municipal water in Walkerton, Ontario, resulted in the worst public health disaster involving municipal water in Canadian history. At least seven people died and 2300 became ill. A public inquiry led by judge Dennis O'Connor examined the events and delineated the causes of the outbreak, including physical causes, the role of the public utilities operators, the public utilities commissioners, the Ministry of the Environment (MOE), and the provincial government. Improper practices and systemic fraudulence by the public utility operators, the recent privatization of municipal water testing, the absence of criteria governing quality of testing, and the lack of provisions made for notification of results to multiple authorities all contributed to the crisis. The MOE noted significant concerns 2 years before the outbreak; however, no changes resulted because voluntary guidelines as opposed to legally binding regulations governed water safety. The inquiry concluded that budgetary restrictions introduced by the provincial government 4 years before the outbreak were enacted with no assessment of risk to human health. The ministers and the cabinet had received warnings about serious risks. Budgetary cuts destroyed the checks and balances that were necessary to ensure municipal water safety.

  4. Effect of Qi-protecting powder (Huqi San) on expression of c-jun, c-fos and c-myc in diethylnitrosamine-mediated hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Xia Li; Zheng-Ming Shi; Ping Feng; Zhao-Yang Wen; Xue-Jiang Wang

    2007-01-01

    AIM: To study the inhibitory effect of Huqi San (Qiprotecting powder) on rat prehepatocarcinoma induced by diethylinitrosamine (DEN) by analyzing the mutational activation of c-fos proto-oncogene and over-expression of c-jun and c-myc oncogenes.METHODS: A Solt-Farber two-step test model of prehepatocarcinoma was induced in rats by DEN and 2-acetylaminofluorene (AAF) to investigate the modifying effects of Huqi San on the expression of c-jun, c-fos and c-myc in DEN-mediated hepatocarcinogenesis. Huqi San was made of eight medicinal herbs containing glycoprival granules, in which each milliliter contains 0.38 g crude drugs. γ-glutamy-transpeptidase-isoenzyme (γ-GTase)was determined with histochemical methods. Level of 8-hydroxydeoxyguanosine (OHdG) formed in liver and c-jun, c-fos and c-myc proto-oncogenes were detected by immunohistochemical methods.RESULTS: The level of 8-OHdG, a mark of oxidative DNA damage, was significantly decreased in the liver of rats with prehepatocarcinoma induced by DEN who received 8 g/kg body weight or 4 g/kg body weight Huqi San before (1 wk) and after DEN exposure (4 wk). Huqi Santreated rats showed a significant decrease in number of γ-GT positive foci (P < 0.001, prevention group: 4.96 ±0.72 vs 29.46 ± 2.17; large dose therapeutic group: 7.53± 0.88 vs 29.46 ± 2.17). On the other hand, significant changes in expression of c-jun, c-fos and c-myc were found in Huqi San-treated rats.CONCLUSION: Activation of c-jun, c-fos and c-myc plays a crucial role in the pathogenesis of liver cancer.Huqi San can inhibit the over-expression of c-jun, c-fos and c-myc oncogenes and liver preneolastic lesionsinduced by DEN.

  5. Validating Community-Led Forest Biomass Assessments.

    Science.gov (United States)

    Venter, Michelle; Venter, Oscar; Edwards, Will; Bird, Michael I

    2015-01-01

    The lack of capacity to monitor forest carbon stocks in developing countries is undermining global efforts to reduce carbon emissions. Involving local people in monitoring forest carbon stocks could potentially address this capacity gap. This study conducts a complete expert remeasurement of community-led biomass inventories in remote tropical forests of Papua New Guinea. By fully remeasuring and isolating the effects of 4,481 field measurements, we demonstrate that programmes employing local people (non-experts) can produce forest monitoring data as reliable as those produced by scientists (experts). Overall, non-experts reported lower biomass estimates by an average of 9.1%, equivalent to 55.2 fewer tonnes of biomass ha(-1), which could have important financial implications for communities. However, there were no significant differences between forest biomass estimates of expert and non-expert, nor were there significant differences in some of the components used to calculate these estimates, such as tree diameter at breast height (DBH), tree counts and plot surface area, but were significant differences between tree heights. At the landscape level, the greatest biomass discrepancies resulted from height measurements (41%) and, unexpectedly, a few large missing trees contributing to a third of the overall discrepancies. We show that 85% of the biomass discrepancies at the tree level were caused by measurement taken on large trees (DBH ≥50 cm), even though they consisted of only 14% of the stems. We demonstrate that programmes that engage local people can provide high-quality forest carbon data that could help overcome barriers to reducing forest carbon emissions in developing countries. Nonetheless, community-based monitoring programmes should prioritise reducing errors in the field that lead to the most important discrepancies, notably; overcoming challenges to accurately measure large trees.

  6. Sonic hedgehog在二乙基亚硝胺诱发大鼠肝癌发生过程中的表达及意义%Expression and Significances of Sonic Hedgehog During Hepatocarcinogenesis Induced by Diethylnitrosamine in the Rats

    Institute of Scientific and Technical Information of China (English)

    王东; 李红星; 李笑岩; 白咸勇; 李雅娜

    2011-01-01

    To observe expression of sonic hedgehog (Shh) in tissue of liver,to explore its role during hepato-carcinogenesis induced by diethylnitrosamine (DEN) in the rats.On the Basis of this liver cancer model,the morphological changes of liver tissue were observed by HE staining,the expression of Shh protein and mR-NA were measured with immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) respectively.Based on morphological characters during the process of hepatocarcinogenesis,the rats were divided into control group,hepatic lesion group,hepatic proliferation/cirrhosis group and hepatic carcinogene-sis group.The cells of Shh protein expression mainly distributed in the epithelia of interlobular bile duct,hy-perplasia node,cancerous tissues and pericancerous tissues.The positive expression rate of Shh protein inthe control group,hepatic toxic lesion,hepatic proliferation/cirrhosis and hepatic carcinogenesis were 0%,30%,53.33% and 79.17% (χ2=42.67,P<0.05) respectively.The expression rate of Shh mRNA increased gradually with the hepatocarcinogenesis (χ2=13.35,P<0.05).The result that the binds of Shh mRNA positive expression were analyzed showed that its expression increased gradually with the hepatocarcinogenesis (F= 110.26,P<0.05).The expression rate of Ptch mRNA increased gradually with the hepatocarcinogenesis(χ2=19.83,P<0.05).The result that the binds of Ptch mRNA positive expression were analyzed showed that its expression increased gradually with the hepatocarcinogenesis (F=68.28,P<0.05).Experimental results in-di-cated that the abnormal expression of Shh caused abnormal activation of Shh signaling pathway,and con-tin-ually affected the cells of liver,and involved the process of hepatocarcinogenesis.%观察肝脏组织中Sonic hedgehog (Shh)的表达情况,探讨其在肝癌发生发展过程中的作用.用二乙基亚硝胺(diethylnitrosamine,DEN)制备诱发型肝癌模型,利用光镜技术观察诱癌过程中肝组织的形态学

  7. A Lifetime Prediction Method for LEDs Considering Real Mission Profiles

    OpenAIRE

    Qu, Xiaohui; Wang, Huai; Zhan, Xiaoqing; Blaabjerg, Frede; Chung, Henry Shu-Hung

    2017-01-01

    The Light-Emitting Diode (LED) has become a very promising alternative lighting source with the advantages of longer lifetime and higher efficiency than traditional ones. The lifetime prediction of LEDs is important to guide the LED system designers to fulfill the design specifications and to benchmark the cost-competitiveness of different lighting technologies. However, the existing lifetime data released by LED manufacturers or standard organizations are usually applicable only for some spe...

  8. Patients' views on a nurse-led prostate clinic.

    Science.gov (United States)

    Townsend, Alison

    Nurse-led clinics are being established in a number of specialties including urology. Men attending a nurse-led clinic for suspected prostate cancer were surveyed to investigate their perception of and satisfaction with a nurse-led clinic and to establish whether this model of care met expectations. The results showed that patients were satisfied with the service. This adds to the growing body of evidence supporting nurse-led services.

  9. Ln(III) complexes as potential phosphors for white LEDs

    NARCIS (Netherlands)

    Akerboom, Sebastiaan

    2013-01-01

    Generating white light with LED technology requires a trick; one of them is to use color-converting (phosphor) layer that covers the LED chip. Suitable phosphors that can be excited with LEDs are scarce, necessitating research in this area. Complexes of the trivalent lanthanoids are interesting cand

  10. EC-LEDS Supports the Low-Carbon Transition

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    EC-LEDS is a flagship U.S. government-led effort that assists countries to create and implement low emission development strategies, or LEDS -- development frameworks that promote sustainable social and economic development while reducing greenhouse gas emissions over the medium to long term.

  11. High Efficiency Driving Electronics for General Illumination LED Luminaires

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Anand

    2012-10-31

    New generation of standalone LED driver platforms developed, which are more efficient These LED Drivers are more efficient (≥90%), smaller in size ( 0.15 in3/watt), lower in cost ( 12 cents/watt in high volumes in millions of units). And these products are very reliable having an operating life of over 50,000 hours. This technology will enable growth of LED light sources in the use. This will also help in energy saving and reducing total life cycle cost of LED units. Two topologies selected for next generation of LED drivers: 1) Value engineered single stage Flyback topology. This is suitable for low powered LED drivers up to 50W power. 2) Two stage boost power factor correction (PFC) plus LLC half bridge platform for higher powers. This topology is suitable for 40W to 300W LED drivers. Three new product platforms were developed to cover a wide range of LED drivers: 1) 120V 40W LED driver, 2) Intellivolt 75W LED driver, & 3) Intellivolt 150W LED driver. These are standalone LED drivers for rugged outdoor lighting applications. Based on these platforms number of products are developed and successfully introduced in the market place meeting key performance, size and cost goals.

  12. Modelling intelligence-led policing to identify its potential

    NARCIS (Netherlands)

    Hengst-Bruggeling, M. den; Graaf, H.A.L.M. de; Scheepstal, P.G.M. van

    2014-01-01

    lntelligence-led policing is a concept of policing that has been applied throughout the world. Despite some encouraging reports, the effect of intelligence-led policing is largely unknown. This paper presents a method with which it is possible to identify intelligence-led policing's potential to inc

  13. Thermal design for the high-power LED lamp

    Energy Technology Data Exchange (ETDEWEB)

    Tian Xiaogai; Chen Wei; Zhang Jiyong, E-mail: tianxiaogai@sina.com [NVC Lighting Technology Corporation Research and Development Center (Shanghai), Shanghai 201112 (China)

    2011-01-15

    This paper summarizes different kinds of heat sinks on the market for high power LED lamps. Analysis is made on the thermal model of LED, PCB and heat sink separately with a simplified mode provided. Two examples of simulation are illustrated as a demonstration for the thermal simulation as guidance for LED lamp design. (semiconductor devices)

  14. A review of passive thermal management of LED module

    NARCIS (Netherlands)

    Ye, H.; Sau, K.; Zeijl, H. van; Gielen, A.W.J.; Zhang, G.

    2011-01-01

    Recently, the high-brightness LEDs have begun to be designed for illumination application. The increased electrical currents used to drive LEDs lead to thermal issues. Thermal management for LED module is a key design parameter as high operation temperature directly affects their maximum light outpu

  15. Design methodologies for reliability of SSL LED boards

    NARCIS (Netherlands)

    Jakovenko, J.; Formánek, J.; Perpiñà, X.; Jorda, X.; Vellvehi, M.; Werkhoven, R.J.; Husák, M.; Kunen, J.M.G.; Bancken, P.; Bolt, P.J.; Gasse, A.

    2013-01-01

    This work presents a comparison of various LED board technologies from thermal, mechanical and reliability point of view provided by an accurate 3-D modelling. LED boards are proposed as a possible technology replacement of FR4 LED boards used in 400 lumen retrofit SSL lamps. Presented design method

  16. LED packaging for lighting applications design, manufacturing, and testing

    CERN Document Server

    Liu, Sheng

    2011-01-01

    Since the first light-emitting diode (LED) was invented by Holonyak and Bevacqua in 1962, LEDs have made remarkable progress in the past few decades with the rapid development of epitaxy growth, chip design and manufacture, packaging structure, processes, and packaging materials. LEDs have superior characteristics such as high efficiency, small size, long life, low power consumption, and high reliability. The market for white LED is growing rapidly in various applications. It has been widely accepted that white LEDs will be the fourth illumination source to substitute the incandescent, fluores

  17. Monolithic Integration of GaN-based LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping, E-mail: jpao@ee.tokushima-u.ac.jp [Institute of Technology and Science, University of Tokushima 2-1 Minami-Josanjima, Tokushima 770-8506 (Japan)

    2011-02-01

    The technology of monolithically integrated GaN-based light-emitting diodes (LEDs) is reported. First, the technology details to realize monolithic integration are described, including the circuit design for high-voltage and alternating current (AC) operation and the technologies for device isolation. The performances of the fabricated monolithic LED arrays are then demonstrated. A monolithic series array with totally 40 LEDs exhibited expected operation function under AC bias. The operation voltage of the array is 72 V when 20 LEDs were connected in series. Some modified circuit designs for high-voltage operation and other monolithic LED arrays are finally reviewed.

  18. Selenium prevents tumor development in a rat model for chemical carcinogenesis

    DEFF Research Database (Denmark)

    Bjorkhem-Bergman, L.; Torndal, U. B.; Eken, S.

    2005-01-01

    Previous studies in animals and humans have shown that selenium compounds can prevent cancer development. In this work we studied the tumor preventive effect of selenium supplementation, administrated as selenite, in the initiation, promotion and progression phases in a synchronized rat model...... for chemically induced hepatocarcinogenesis, the resistant hepatocyte model. Selenite in supra-nutritional but subtoxic doses (1 and 5 p.p.m.) was administrated to the animals through the drinking water. Such supplementation during the initiation phase did not have a tumor preventive effect. However, selenite...... of the selenoenzyme glutathione peroxidase was essentially unaltered. Selenite treatment (5 p.p.m.) during the progression phase resulted in a significantly lower volume fraction of liver tumors (14 compared with 26%) along with a decrease in cell proliferation within the tumors (34 compared with 63%). Taken together...

  19. [Study of achieving white organic LED by fluorescence dye].

    Science.gov (United States)

    Wang, Jin; Wang, Jing; Zheng, Rong-er; Meng, Ji-wu

    2005-08-01

    Some hybrid organic LEDs are made by using fluorescence dye and InGaN blue-light chip and the possibility of achieving white organic LED is investigated according to light conversion theory. Firstly, the LEDs made by normal method and double-dotting glue method are studied. It is found that the double-dotting glue method is too complex and the LEDs made by this way is low-luminance, so it isn't fit to make LED. Secondly the different weight ratio of 1/1/100, 1/1/200, 2/1.5/100 ax-17/zq-13/AB LEDs are manufactured. The 2/1.5/100 LED's color coordinate is (0.32, 0.30), approaching to white point and the correlative color temperature is 6290K which is close to sunlight. So it is a relatively ideal white lamp-house.

  20. LED lighting for greenhouses. Final report; LED belysning til vaeksthuse. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    OEstergaard, J.E. (Syddansk Univ. (SDU). Erhvervsinnovation og Teknologi, Odense (Denmark))

    2011-01-15

    The project had 3 main objectives: 1) To develop a prototype of a LED-based luminaire that can replace the existing glasshouse horticultural lighting. The project have developed a working prototype and experimentally replaced the traditional HPS luminaires in a controlled growing area. The project succeeded in producing plants of comparable quality. However, the project shows that the prototype can be improved by: x) being further integrated into the existing horticultural production technology (eg climate computers and purchase of electricity) x) adapting configuration of luminaires specifically to each plant variety x) adapting different cooling technologies to match specific customer needs x) In some cases being combined with heat input to optimize the overall economy. 2) To achieve an effective electricity savings of 50-80% - equivalent to a value of approx. DKK 5 million for a medium sized nursery. The verified electricity savings was 40%. In test setups and in well defined and controllable production areas the prototypes achieved electricity savings of > 50%. It is expected that a new generation of LEDs (Q3 2010) will allow for greater power savings. 3) To continue prototype development and initiate commercialization of the project through the company Fionia Lighting A/S. The shareholders of the company have allocated capital to the company to allow us to address the main challenges in commercializing the technology. It is expected that the company will enter a strategic alliance with a major industrial player in the beginning of 2011. (Author)

  1. High performance LED lamps for the automobile: needs and opportunities

    Science.gov (United States)

    Pohlmann, Wolfgang; Vieregge, Thomas; Rode, Martin

    2007-09-01

    Light emitting diodes have been an option in automotive lighting for more than 15 years now. The capacities and colours of LEDs available in the recent past were sufficient to realize interior lighting and rear signalling functions. In the meantime, series applications, such as position or daytime running lights, using white LEDs for signal functions in headlamps, are no longer a rarity. The next step - realizing main lighting functions for series applications - is imminent. LED will offer a multitude of styling options in rear and front lighting, as well as a light colour which differs considerably from that of the previous halogen and xenon headlamp systems. The further advantages of the LED compared with conventional light sources with regard to service life, power efficiency and package space requirements can thus only be sensibly exploited by means of suitable structural and connection techniques. Increasing complexity and installation conditions in an often rough environment are demanding challenge to realize the hardware of LED lamps. In this paper at first the requirements on LEDs and LED modules in automotive exterior lighting will be discussed. Furthermore the status of industrialization and modular concepts for signal lamps and full LED headlamps will be presented. The paper will finish with a discussion of new headlamp active lighting functions like maker light or glare free high beam, implemented in hybrid or with pure LED technology. In the subsequent headlamp integration, from about 2012, freely-addressable LED-Arrays will possibly enable these new types of lighting functions.

  2. Development of high-performance solar LED lighting system

    KAUST Repository

    Huang, B.J.

    2010-08-01

    The present study developed a high-performance charge/discharge controller for stand-alone solar LED lighting system by incorporating an nMPPO system design, a PWM battery charge control, and a PWM battery discharge control to directly drive the LED. The MPPT controller can then be removed from the stand-alone solar system and the charged capacity of the battery increases 9.7%. For LED driven by PWM current directly from battery, a reliability test for the light decay of LED lamps was performed continuously for 13,200 h. It has shown that the light decay of PWM-driven LED is the same as that of constant-current driven LED. The switching energy loss of the MOSFET in the PWM battery discharge control is less than 1%. Three solar-powered LED lighting systems (18 W, 100 W and 150 W LED) were designed and built. The long-term outdoor field test results have shown that the system performance is satisfactory with the control system developed in the present study. The loss of load probability for the 18 W solar LED system is 14.1% in winter and zero in summer. For the 100 W solar LED system, the loss of load probability is 3.6% in spring. © 2009 Elsevier Ltd. All rights reserved.

  3. The PV LED Engine - a new generation of intelligent solar powered LED lighting

    DEFF Research Database (Denmark)

    Poulsen, Peter Behrensdorff; Thorsteinsson, Sune

    to dispose intelligently over the energy.To validate the model high-end PV products on the market has been bought, simulated and thewhole electrical system been characterized electrically (battery, LED, electrical circuit, PV) and optical properties of the optical system in front of the solar panel......Digging down cables for small electrical applications in the urban environment is extremely expensivedue to the high labour cost associated with it. Small stand-alone PV applications powered by 0.5-50 Wp can become very attractive since e.g. in Copenhagen in Denmark the cost of digging down cables...... in thecity is about 1000 $ pr. meter so the cost savings on the cable digging can easily pay for the solar cells. The requirements to the products from the municipalities are high so if e.g. the products are for lighting purpose the reliability of the product meeting some specied amount of light is very...

  4. Modification of Luminescent Properties of Red Sulphide Phosphors for White LED Lighting

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A kind of sulphide, CaS:Eu2+, activated by europium ion for white LED lighting was synthesized via solid-state reaction route in reducing atmospheres. The phosphors were then encapsulated with silicone resin. Moreover, chemical structure of the phosphors was characterized by XRD. Microstructure of the powders was observed by SEM. Spectra of excitation and emission for the phosphors were also obtained by a spectrophotometer. Effect of processing parameters on the luminescent properties of the powders was systematically studied to result in the phosphors with good chemical stability and maximal relative luminescent intensity.

  5. Spectral Design Flexibility of LED Brings Better life

    DEFF Research Database (Denmark)

    Ou, Haiyan; Corell, Dennis Dan; Ou, Yiyu

    2012-01-01

    white light using different color mixing schemes. The spectral design flexibility of white LED light sources will promote them for novel applications to improve the life quality of human beings. As an initial exploration to make use of the spectral design flexibility, we present an example: 'no blue......' white LED light source for sufferers of disease Porphyria. An LED light source prototype, made of high brightness commercial LEDs applying an optical filter, was tested by a patient suffering from Porphyria. Preliminary results have shown that the sufferer could withstand the light source for much......Light-emitting diodes (LEDs) are penetrating into the huge market of general lighting because they are energy saving and environmentally friendly. The big advantage of LED light sources, compared to traditional incandescent lamps and fluorescent light tubes, is the flexible spectral design to make...

  6. Effect of LED lamping on the chlorophylls of leaf mustard

    Science.gov (United States)

    Wu, Shiqiang; Zhu, Liang; Zhao, Fuli; Yang, Bowen; Chen, Zuxin; Cai, Ruhai; Chen, Jiansheng

    The absorption coefficients of chloroplast of leaf mustard were measured by a spectrophotometer. The leaves were collected from seven treatments with different lighting. The chlorophyll content was calculated following Arnon equation. LEDs for filling the light source can increase the conduction of plants. Compared with other treatments, Chlorophyll in the leaves got an higher concentration under the lamping of red LEDS to blue LEDS for 7:1 .

  7. Recent results on the degradation of white LEDs for lighting

    OpenAIRE

    Meneghesso, G.; Meneghini, M.; Zanoni, E.

    2010-01-01

    Abstract Over the last years, GaN-based LEDs have shown to be excellent candidates for the realization of highefficiency light sources. White LEDs based on phosphor conversion can reach record efficiencies in excess of 150 lm/W, as demonstrated by several manufacturers and research groups. However, the reliability of white LEDs is still limited by a number of issuesthat must be addressed before these devices can find wide application in the market. This paper gives an overview on the most ...

  8. Automated selection of LEDs by luminance and chromaticity coordinate

    CERN Document Server

    Fischer, Ulrich H P; Reinboth, Christian

    2010-01-01

    The increased use of LEDs for lighting purposes has led to the development of numerous applications requiring a pre-selection of LEDs by their luminance and / or their chromaticity coordinate. This paper demonstrates how a manual pre-selection process can be realized using a relatively simple configuration. Since a manual selection service can only be commercially viable as long as only small quantities of LEDs need to be sorted, an automated solution suggests itself. This paper introduces such a solution, which has been developed by Harzoptics in close cooperation with Rundfunk Gernrode. The paper also discusses current challenges in measurement technology as well as market trends.

  9. The Application of Multiple Attribute Decision in LED Commerce Platform

    Directory of Open Access Journals (Sweden)

    Huahuan LEI

    2013-04-01

    Full Text Available The paper applied multiple attribute decision making into LED collaborative commerce platform to help customers make purchase decision. The normal customers are unfirmiliar with LED lighting product, because it is latest product in lighting industry and the attributes of LED are complicated and professional. The method analyzed the essential attributes and network attributes of LED lighting products to sequence the limited alternative. And based on the shortage of TOPSIS method, the paper combined grey correlation with TOPSIS method in order to make decision more exactly.

  10. Horizontally assembled green InGaN nanorod LEDs: scalable polarized surface emitting LEDs using electric-field assisted assembly

    Science.gov (United States)

    Park, Hoo Keun; Yoon, Seong Woong; Eo, Yun Jae; Chung, Won Woo; Yoo, Gang Yeol; Oh, Ji Hye; Lee, Keyong Nam; Kim, Woong; Do, Young Rag

    2016-01-01

    In this study, we report the concerted fabrication process, which is easy to transform the size of active emitting area and produce polarized surface light, using the electric-field-assisted assembly for horizontally assembled many tiny nanorod LEDs between two metal electrodes. We fabricate the millions of individually separated 1D nanorod LEDs from 2D nanorod arrays using nanosphere lithography, etching and cutting process of InGaN/GaN LED structure on a flat sapphire substrate. The horizontally assembled InGaN-based nanorods LED device shows bright (~2,130 cd/m2) and uniform polarized (polarization ratio, ρ = ~0.61) green emissions from large area (0.7 cm × 0.6 cm) planar surface. The realization of a horizontally assembled nanorod LED device can prove the concept of an innovative idea to fabricate formable and scalable polarized surface LED lighting. PMID:27324568

  11. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  12. Éalonnage de sources lumineuses de type LED

    DEFF Research Database (Denmark)

    Durix, Bastien; Quéau, Yvain; Lucas, Tom

    We describe three calibration methods of a LED (light-emitting diode), in order to apply photometric stereo to a scene illuminated by LEDs. The most accurate of these methods will allow us to obtain very realistic 3D models. Nevertheless, the scene must remain still during the whole shooting sequ...

  13. Development of an intelligent integrated LED system-in-package

    NARCIS (Netherlands)

    Gielen, A.W.J.; Hesen, P.; Swartjes, F.H.M.; Zeijl, H. van; Boschman, F.; Bullema, J.-E.; Werkhoven, R.J.; Koh, S.

    2011-01-01

    Intelligent LED lighting systems can save up to 80% of energy compared to traditional lighting systems. In order to provide these intelligent lighting products at reaseonable costs, integration and miniaturisation are important steps. To this end we have designed a LED system-in-package that combine

  14. Student-Led Parent Conferences: A Model for Teaching Responsibility.

    Science.gov (United States)

    Guyton, Jane M.; Fielstein, Lynda L.

    1989-01-01

    Describes program in which elementary school students lead parent-teacher conferences, shares authors' experiences with the student-led conferences, and discusses how the process has fostered student responsibility. Describes results of informal study that support the student-led conference. (NB)

  15. Remotely Triggered Solar Blind Signaling Using Deep Ultraviolet (UV) LEDs

    Science.gov (United States)

    2011-06-01

    distance from the LED to the photodiode was not held constant. To avoid the output voltage limit on the opamp , the intensity of the four HS LEDs was...period for driving voltages up to 8.0 volts. As before, a GaP photodiode was used in conjunction with an opamp , but the output voltage was read with an

  16. Flicker Reduction in LED-LCDs with Local Backlight

    DEFF Research Database (Denmark)

    Nadernejad, Ehsan; Mantel, Claire; Burini, Nino;

    2013-01-01

    Local backlight dimming of LCD with LED backlight can reduce power consumption and improve quality of displayed images and videos. However, important variations of LED over time produce a visually annoying artifact called flickering. In this work, we propose a new algorithm to reduce flickering w...

  17. Low Cost Lithography Tool for High Brightness LED Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Andrew Hawryluk; Emily True

    2012-06-30

    The objective of this activity was to address the need for improved manufacturing tools for LEDs. Improvements include lower cost (both capital equipment cost reductions and cost-ofownership reductions), better automation and better yields. To meet the DOE objective of $1- 2/kilolumen, it will be necessary to develop these highly automated manufacturing tools. Lithography is used extensively in the fabrication of high-brightness LEDs, but the tools used to date are not scalable to high-volume manufacturing. This activity addressed the LED lithography process. During R&D and low volume manufacturing, most LED companies use contact-printers. However, several industries have shown that these printers are incompatible with high volume manufacturing and the LED industry needs to evolve to projection steppers. The need for projection lithography tools for LED manufacturing is identified in the Solid State Lighting Manufacturing Roadmap Draft, June 2009. The Roadmap states that Projection tools are needed by 2011. This work will modify a stepper, originally designed for semiconductor manufacturing, for use in LED manufacturing. This work addresses improvements to yield, material handling, automation and throughput for LED manufacturing while reducing the capital equipment cost.

  18. Single phase forced convection cooling of high power leds

    NARCIS (Netherlands)

    Ozdemir, M.Z.; Chestakov, D.; Frijns, A.J.H.

    2011-01-01

    LEDs are strong candidates for future illumination applications dueto their much lower consumption of energy compared to conventional lighting options. One of key problems in development of LEDs is successful thermal management during illumination. Therefore, current research ongoing related to high

  19. Thermo-mechanical model optimization of HB-LED packaging

    NARCIS (Netherlands)

    Yuan, C.A.; Erinc, M.; Gielen, A.W.J.; Waal, A. van der; Driel, W. van; Zhang, K.

    2011-01-01

    Lighting is an advancing phenomenon both on the technology and on the market level due to the rapid development of the solid state lighting technology. The efforts in improving the efficacy of high brightness LED's (HB-LED) have concentrated on the packaging architecture. Packaging plays a significa

  20. Luminous flux and colour maintenance investigation of integrated LED lamps

    DEFF Research Database (Denmark)

    Corell, Dennis Dan; Thorseth, Anders; Dam-Hansen, Carsten

    2014-01-01

    This article will present an investigation of the luminous flux and colour maintenance of white LED based retrofit lamps. The study includes 23 different types of integrated LED lamps, covering 18 directional and 5 non-directional. Luminous flux and colour data for operation up to 20000 h has been...

  1. Thermal analysis of LED lamps for optimal driver integration

    NARCIS (Netherlands)

    Perpiñà, X.; Werkhoven, R.J.; Vellvehi, M.; Jakovenko, J.; Jordà, X.; Kunen, J.M.G.; Bancken, P.; Bolt, P.J.

    2015-01-01

    This paper studies the thermal influence of a light-emitting diode (LED) driver on a retrofit LED lamp, also reporting on a procedure for its thermal characterization and multiscale modeling. In this analysis, temperature is measured by infrared thermography and monitoring specific locations with th

  2. Shortest exposure time possible with LED curing lights

    NARCIS (Netherlands)

    Busemann, I.; Lipke, C.; Schattenberg, A.V.M.B.; Willershausen, B.; Ernst, C.P.

    2011-01-01

    PURPOSE: To investigate the shortest exposure time of different light emitting diode (LED)-curing devices for different resin composites in a clinically relevant laboratory model. METHODS: Nine LED curing devices (Bluephase, Bluephase 16i, Bluephase G2, Bluephase 20i/Ivoclar Vivadent, DEMI/sds Kerr,

  3. Chemical carcinogenesis

    Directory of Open Access Journals (Sweden)

    Paula A. Oliveira

    2007-12-01

    Full Text Available The use of chemical compounds benefits society in a number of ways. Pesticides, for instance, enable foodstuffs to be produced in sufficient quantities to satisfy the needs of millions of people, a condition that has led to an increase in levels of life expectancy. Yet, at times, these benefits are offset by certain disadvantages, notably the toxic side effects of the chemical compounds used. Exposure to these compounds can have varying effects, ranging from instant death to a gradual process of chemical carcinogenesis. There are three stages involved in chemical carcinogenesis. These are defined as initiation, promotion and progression. Each of these stages is characterised by morphological and biochemical modifications and result from genetic and/or epigenetic alterations. These genetic modifications include: mutations in genes that control cell proliferation, cell death and DNA repair - i.e. mutations in proto-oncogenes and tumour suppressing genes. The epigenetic factors, also considered as being non-genetic in character, can also contribute to carcinogenesis via epigenetic mechanisms which silence gene expression. The control of responses to carcinogenesis through the application of several chemical, biochemical and biological techniques facilitates the identification of those basic mechanisms involved in neoplasic development. Experimental assays with laboratory animals, epidemiological studies and quick tests enable the identification of carcinogenic compounds, the dissection of many aspects of carcinogenesis, and the establishment of effective strategies to prevent the cancer which results from exposure to chemicals.A sociedade obtém numerosos benefícios da utilização de compostos químicos. A aplicação dos pesticidas, por exemplo, permitiu obter alimento em quantidade suficiente para satisfazer as necessidades alimentares de milhões de pessoas, condição relacionada com o aumento da esperança de vida. Os benefícios estão, por

  4. Spectral design of new dynamic LED light sources

    DEFF Research Database (Denmark)

    Thorseth, Anders

    The use of LED technology in lighting applications, termed Solid State Lighting, is increasing drastically these years due to increasing flux and efficiency of LED components. The advantages of using Solid State Lighting is not only energy savings but the possibility to create new dynamic light...... sources that can be varied in color temperature and achieving color rendering properties. New LED light sources are constructed as clusters of colored LEDs. Modeling and optimization of the control of the light from the individual LEDs is a necessity for the desired operation of the new dynamic light...... source. Detailed knowledge of the spectral power distribution as a function of operating current and temperature is required for the modeling and optimization. Examples of new high color quality dynamic white light sources that can be tuned from warm white light at 2700 K to cold white light at 6500 K...

  5. 'No blue' LED solution for photolithography room illumination

    DEFF Research Database (Denmark)

    Ou, Haiyan; Corell, Dennis Dan; Dam-Hansen, Carsten

    2010-01-01

    This paper explored the feasibility of using a LED-based bulb as the illumination light source for photolithography room. A no-blue LED was designed, and the prototype was fabricated. The spectral power distribution of both the LED bulb and the yellow fluorescent tube was measured. Based on that...... color rendering ability than the YFT. Furthermore, LED solution has design flexibility to improve it further. The prototype has been tested with photoresist SU8-2005. Even after 15 days of illumination, no effect was observed. So this LED-based solution was demonstrated to be a very promising light...... source for photolithography room illumination due to its better color rendering in addition to energy efficiency, long life time and design flexibility....

  6. Indoor visual positioning system using LED and mobile phone

    Science.gov (United States)

    Gong, Yingkui; Shi, Zhengfa; Wang, Yuqi

    2016-01-01

    An indoor visual positioning system is proposed, which using four or more LED ceiling lamps and a mobile phone. A 4*4 photodiode array is attached to the mobile phone to receive the three-dimensional coordinates of the LED lamps via visible light communication, and the front camera of the mobile phone is used to receive the high resolution image of the LED lamps. The mobile phone's three-dimensional coordinates can be determined by matching the spot information and three-dimensional coordinates of the LED lamps with the image information provided by the mobile phone. An improved collinear equation model is proposed to build the mapping relationship between the three-dimensional coordinates of the LED lamps and the image information acquired by the front camera. A semi-physical simulation has been conducted and analyzed. The positioning scheme is proved to be valid and the positioning accuracy is up to decimeter level.

  7. Inexpensive LED-based spectrophotometer for analyzing optical coatings

    CERN Document Server

    Hardie, Kayla; Kuntz, Katanya B; Jennewein, Thomas

    2016-01-01

    Optical coatings are widespread in everyday life, from camera lenses to glasses, to complex optics experiments. A simple, reliable device that can quickly and inexpensively analyze optical coatings is a valuable laboratory tool. Such a device can identify unknown or mislabelled optics, and characterize the transmission spectra of optical elements used in an experiment. We present the design and characterization of a LED-based spectrophotometer, and demonstrate its ability to identify different optical coatings. Our approach uses ten LEDs that cover a spectrum from 365 nm to 1000 nm. A small servomotor and microcontroller rotates a LED board to sequentially position each LED over an optical sample, and the transmitted light corresponding to each LED is measured with a silicon photodetector. The device is automated, portable, inexpensive, user-friendly and simple to build.

  8. GaN-based LEDs for light communication

    Science.gov (United States)

    Zhao, LiXia; Zhu, ShiChao; Wu, ChunHui; Yang, Chao; Yu, ZhiGuo; Yang, Hua; Liu, Lei

    2016-10-01

    Rapid improvement in the efficiency of GaN-based LEDs not only speed up its applications for general illumination, but offer the possibilities for data transmission. This review is to provide an overview of current progresses of GaN-based LEDs for light communications. The modulation bandwidth of GaN-based LEDs has been first improved by optimizing the LED epilayer structures and the modulation bandwidth of 73 MHz was achieved at the driving current density of 40 A/cm2 by changing the multi-quantum well structures. After that, in order to increase the current density tolerance, different parallel flip-chip micro-LED arrays were fabricated. With a high injected current density of ˜7900 A/cm2, a maximum modulation bandwidth of ˜227 MHz was obtained with optical power greater than 30 mW. Besides the increase of carrier concentrations, the radiative recombination coefficient B was also enhanced by modifying the photon surrounding environment based on some novel nanostructures such as resonant cavity, surface plasmon, and photonic crystals. The optical 3 dB modulation bandwidth of GaN-based nanostructure LEDs with Ag nanoparticles was enhanced by 2 times compared with GaN-based nanostructure LEDs without Ag nanoparticles. Our results demonstrate that using the QW-SP coupling can effectively help to enhance the carrier spontaneous emission rate and also increase the modulation bandwidth for LEDs, especially for LEDs with high intrinsic IQE. In addition, we discuss the progress of the faster color conversion stimulated by GaN-based LEDs.

  9. Lateral epitaxial overgrowth of aluminum nitride and near ultraviolet LEDs for white lighting applications

    Science.gov (United States)

    Newman, Scott A.

    In recent years, substantial efforts have been made to develop deep ultraviolet AlGaN-based LEDs (200-280 nm) for specialized applications such as bio-detection and non-line-of-sight (NLOS) communications. One of several factors limiting the performance of these devices is the high threading dislocation (TD) density of ˜5x109 cm-2 that results from growing the required AlN base layer on either a SiC or sapphire substrate. Lateral epitaxial overgrowth (LEO) of AlN, the first topic of this dissertation, is a promising technology for growing low TD density AlN templates. Conventional LEO methods relying on selective area growth (SAG) have not been effective for AlxGa1-xN with x > 0.2, because of the high aluminum sticking coefficient for the mask materials and/or contamination of the film by the mask. Therefore, maskless AlN LEO was investigated using metal organic chemical vapor deposition (MOCVD) and hydride vapor phase epitaxy (HVPE). Cracked AlN films with TD densities of LEDs for white lighting applications. Currently, cool white LEDs consisting of a blue GaN/InGaN LED and the YAG:Ce3+ yellow phosphor are available with 107 lm/W efficacy, but have have high correlated color temperatures (CCTs) of ˜5,500 K and poor color rendering indices (CRIs) of ˜75. The alternative approach of combining a NUV LED with suitable NUV-excitation phosphors (e.g., red, green, and blue phosphors) can theoretically allow for high CRI white lighting with relatively good efficacy and a variety of CCTs. When this project began in late 2007, the lack of suitable blue-excitation phosphors suggested that this was the only viable approach to attaining very high CRI white lighting. NUV LEDs with AlN buffers on 6H-SiC substrates and AlGaN/InGaN active regions were first developed to target white phosphors with excitation peaks near 365 nm. Later, NUV LEDs with GaN buffers on sapphire substrates and GaN/InGaN active regions were developed to diagnose problems with the AlGaN/InGaN LEDs and to

  10. Chemical space and biology.

    Science.gov (United States)

    Dobson, Christopher M

    2004-12-16

    Chemical space--which encompasses all possible small organic molecules, including those present in biological systems--is vast. So vast, in fact, that so far only a tiny fraction of it has been explored. Nevertheless, these explorations have greatly enhanced our understanding of biology, and have led to the development of many of today's drugs. The discovery of new bioactive molecules, facilitated by a deeper understanding of the nature of the regions of chemical space that are relevant to biology, will advance our knowledge of biological processes and lead to new strategies to treat disease.

  11. Development of Vehicle Lighting System Using LED Application

    Directory of Open Access Journals (Sweden)

    Asmarashid Ponniran

    2011-12-01

    Full Text Available A Light Emitting Diode (LED is a semiconductor device which converts electricity into light. LEDs are preferred over incandescent lamps because of their long life and their availability in various colors and brightness levels. The aim of this paper is to present the development of vehicle lighting system using LED application. In this system, high power LEDs type is chosen as automobile headlight model and controller circuit using microcontroller is considered. The LEDs are driven using buck converter circuit with appropriate Pulse Width Modulation (PWM signal whereby the PWM signals are generated by microcontroller. The system is divided into 2 modes of operation, manual and automatic. The automatic mode of operation will be operating when the LDR senses the level of light brightness whereby the level of brightness is proportion to duty cycle of PWM. Meanwhile, for the manual mode of operation, 3 switches which are SW2 with 20% duty cycle, SW3 with 40% duty cycle and SW3 with 80% duty cycle are developed. The result shows that the maximum brightness of LED is about 127.6 Lumen at 80% of duty cycle for manual operation mode. Besides, by varying theduty cycle of PWM signal for both modes of operation, manual and automatic, LED brightness can be controlled.

  12. Vision communications based on LED array and imaging sensor

    Science.gov (United States)

    Yoo, Jong-Ho; Jung, Sung-Yoon

    2012-11-01

    In this paper, we propose a brand new communication concept, called as "vision communication" based on LED array and image sensor. This system consists of LED array as a transmitter and digital device which include image sensor such as CCD and CMOS as receiver. In order to transmit data, the proposed communication scheme simultaneously uses the digital image processing and optical wireless communication scheme. Therefore, the cognitive communication scheme is possible with the help of recognition techniques used in vision system. By increasing data rate, our scheme can use LED array consisting of several multi-spectral LEDs. Because arranged each LED can emit multi-spectral optical signal such as visible, infrared and ultraviolet light, the increase of data rate is possible similar to WDM and MIMO skills used in traditional optical and wireless communications. In addition, this multi-spectral capability also makes it possible to avoid the optical noises in communication environment. In our vision communication scheme, the data packet is composed of Sync. data and information data. Sync. data is used to detect the transmitter area and calibrate the distorted image snapshots obtained by image sensor. By making the optical rate of LED array be same with the frame rate (frames per second) of image sensor, we can decode the information data included in each image snapshot based on image processing and optical wireless communication techniques. Through experiment based on practical test bed system, we confirm the feasibility of the proposed vision communications based on LED array and image sensor.

  13. A Lifetime Prediction Method for LEDs Considering Real Mission Profiles

    DEFF Research Database (Denmark)

    Qu, Xiaohui; Wang, Huai; Zhan, Xiaoqing

    2017-01-01

    The Light-Emitting Diode (LED) has become a very promising alternative lighting source with the advantages of longer lifetime and higher efficiency than traditional ones. The lifetime prediction of LEDs is important to guide the LED system designers to fulfill the design specifications and to ben......The Light-Emitting Diode (LED) has become a very promising alternative lighting source with the advantages of longer lifetime and higher efficiency than traditional ones. The lifetime prediction of LEDs is important to guide the LED system designers to fulfill the design specifications...... operations due to the varying operational and environmental conditions during the entire service time (i.e., mission profiles). To overcome the challenge, this paper proposes an advanced lifetime prediction method, which takes into account the field operation mission profiles and also the statistical...... properties of the life data available from accelerated degradation testing. The electrical and thermal characteristics of LEDs are measured by a T3Ster system, used for the electro-thermal modeling. It also identifies key variables (e.g., heat sink parameters) that can be designed to achieve a specified...

  14. Reliability test and failure analysis of high power LED packages*

    Institute of Scientific and Technical Information of China (English)

    Chen Zhaohui; Zhang Qin; Wang Kai; Luo Xiaobing; Liu Sheng

    2011-01-01

    A new type application specific light emitting diode (LED) package (ASLP) with freeform polycarbonate lens for street lighting is developed, whose manufacturing processes are compatible with a typical LED packaging process. The reliability test methods and failure criterions from different vendors are reviewed and compared. It is found that test methods and failure criterions are quite different. The rapid reliability assessment standards are urgently needed for the LED industry. 85 ℃/85 RH with 700 mA is used to test our LED modules with three other vendors for 1000 h, showing no visible degradation in optical performance for our modules, with two other vendors showing significant degradation. Some failure analysis methods such as C-SAM, Nano X-ray CT and optical microscope are used for LED packages. Some failure mechanisms such as delaminations and cracks are detected in the LED packages after the accelerated reliability testing. The finite element simulation method is helpful for the failure analysis and design of the reliability of the LED packaging. One example is used to show one currently used module in industry is vulnerable and may not easily pass the harsh thermal cycle testing.

  15. LED lamps in shipboard lighting systems: Aspects of electromagnetic compatibility

    Directory of Open Access Journals (Sweden)

    Beley V. F.

    2016-12-01

    Full Text Available Trends in the development of different types of light sources and their energy characteristics have been described in the paper. Analysis of regulatory documents has been given. The results of experimental studies of a number of modern LED lamps have been described. Investigation has been made for a number of LED lamps produced by Philips, Xavax and Melitec. The experimental data have been obtained with the complex of devices: the dual-channel oscilloscope (GDS-71042, the power quality analyzer (Fluke-434 and the multi-function device EcoLight-01 (light-, pulse- and luminance meter. It has been shown that operation of LED lamps is characterized by emission of higher current harmonics and reactive power consumption, which depends on the type and design of the lamp driver. It has been found that the value of luminance created by LED lamps in case of acceptable (for ships prolonged deviation of voltage (–10 % is reduced by 3 %; in case of permissible short-term voltage deviation (–20 % luminance is reduced by 7 %. For incandescent lamps this indicator is characterized by a decrease in luminance by 40 % and 60 %, respectively. Despite the low sensitivity to voltage changes (in comparison with other types of lamps, the operation of LED lamps is also associated with the appearance of flicker. Absence of limitations for fluctuations of the light flux in shipboard lighting systems and imperfection of methods for determining the flicker make it difficult to ensure electromagnetic compatibility of LED lamps. Therefore due to reliability, environmental friendliness, energy efficiency and lumen maintenance LED lamps have prospects for introduction into shipboard lighting systems. However, to ensure electromagnetic compatibility of LED lighting systems it is necessary to conduct a detailed study of energy characteristics of LED lamps and to develop appropriate regulatory requirements and technical solutions.

  16. Essentials for Successful and Widespread LED Lighting Adoption

    Science.gov (United States)

    Khan, Nisa

    2011-03-01

    Solid-state lighting (SSL), with light-emitting diodes (LEDs) as the light source, is a growing and essential field, particularly in regard to the heightened need for global energy efficiency. In recent years, SSL has experienced remarkable advances in efficiency, light output magnitude and quality. Thus such diverse applications as signage, message centers, displays, and special lighting are now adopting LEDs, taking 2010's market to 9.1 billion - 68% growth from the previous year! While this is promising, future growth in both display and lighting applications will rely upon unveiling deeper understanding and key innovations in LED lighting science and technologies. In this presentation, some LED lighting fundamentals, engineering challenges and novel solutions will be discussed to address reduction in efficiency (a.k.a. droop) at high currents, and to obtain uniform light distribution for overcoming LEDs' directional nature. The droop phenomenon has been a subject of much controversy in the industry and despite several studies and claims, a widely-accepted explanation still lacks because of counter arguments and experiments. Recently several research studies have identified that the droop behavior in nitride-based LEDs beyond certain current density ranges can only be comprehensively explained if the current leaking beyond the LED active region is included. Although such studies have identified a few useful current leakage mechanisms outside the active region, no one has included current leakage, due to non-ideal, 3-D device structures that create undesirable current distribution inside and outside the active region. This talk will address achieving desirable current distributions from optimized 3-D device structures that should reduce current leakage and hence the droop behavior. In addition to novel LED design solutions for droop reduction and uniform light distribution, the talk will address cost and yield concerns as they pertain to core material scarcity

  17. LOW-COST LED LUMINAIRE FOR GENERAL ILLUMINATION

    Energy Technology Data Exchange (ETDEWEB)

    Lowes, Ted

    2014-07-31

    During this two-year Solid-State Lighting (SSL) Manufacturing R&D project Cree developed novel light emitting diode (LED) technologies contributing to a cost-optimized, efficient LED troffer luminaire platform emitting at ~3500K correlated color temperature (CCT) at a color rendering index (CRI) of >90. To successfully achieve program goals, Cree used a comprehensive approach to address cost reduction of the various optical, thermal and electrical subsystems in the luminaire without impacting performance. These developments built on Cree’s high- brightness, low-cost LED platforms to design a novel LED component architecture that will enable low-cost troffer luminaire designs with high total system efficacy. The project scope included cost reductions to nearly all major troffer subsystems as well as assembly costs. For example, no thermal management components were included in the troffer, owing to the optimized distribution of compact low- to mid-power LEDs. It is estimated that a significant manufacturing cost savings will result relative to Cree’s conventional troffers at the start of the project. A chief project accomplishment was the successful development of a new compact, high-efficacy LED component geometry with a broad far-field intensity distribution and even color point vs. emission angle. After further optimization and testing for production, the Cree XQ series of LEDs resulted. XQ LEDs are currently utilized in Cree’s AR series troffers, and they are being considered for use in other platforms. The XQ lens geometry influenced the independent development of Cree’s XB-E and XB-G high-voltage LEDs, which also have a broad intensity distribution at high efficacy, and are finding wide implementation in Cree’s omnidirectional A-lamps.

  18. Optimized Phosphors for Warm White LED Light Engines

    Energy Technology Data Exchange (ETDEWEB)

    Setlur, Anant; Brewster, Megan; Garcia, Florencio; Hill, M. Christine; Lyons, Robert; Murphy, James; Stecher, Tom; Stoklosa, Stan; Weaver, Stan; Happek, Uwe; Aesram, Danny; Deshpande, Anirudha

    2012-07-30

    The objective of this program is to develop phosphor systems and LED light engines that have steady-state LED efficacies (using LEDs with a 60% wall-plug efficiency) of 105–120 lm/W with correlated color temperatures (CCT) ~3000 K, color rendering indices (CRI) >85, <0.003 distance from the blackbody curve (dbb), and <2% loss in phosphor efficiency under high temperature, high humidity conditions. In order to reach these goals, this involves the composition and processing optimization of phosphors previously developed by GE in combination with light engine package modification.

  19. University of Nevada Las Vegas LED Display Engineering

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-08-31

    The primary objective of this part of the project is to develop and implement a method that compensates for the inefficiency of the green LED. The proposed engineering solution which will be the backbone of this project will be to use RGBW combination in every pixel to save energy. Two different RGBW geometrical pixel configurations will be implemented and compared against traditional LED configurations. These configurations will be analyzed for energy efficiency while keeping the quality of the display the same. Cost of the addition of white LEDs to displays along with energy cost savings will be presented and analyzed.

  20. Energy efficient LED layout optimization for near-uniform illumination

    Science.gov (United States)

    Ali, Ramy E.; Elgala, Hany

    2016-09-01

    In this paper, we consider the problem of designing energy efficient light emitting diodes (LEDs) layout while satisfying the illumination constraints. Towards this objective, we present a simple approach to the illumination design problem based on the concept of the virtual LED. We formulate a constrained optimization problem for minimizing the power consumption while maintaining a near-uniform illumination throughout the room. By solving the resulting constrained linear program, we obtain the number of required LEDs and the optimal output luminous intensities that achieve the desired illumination constraints.

  1. Iluminación LED. Un arma de doble filo

    OpenAIRE

    Sánchez de Miguel, Alejandro

    2004-01-01

    La iluminación LED es el futuro de la iluminación. Sin embargo, como toda tecnología, puede usarse de manera correcta o incorrecta. En el caso de los LED, el abaratamiento de la producción de luz podría provocar un aumento descontrolado de la Contaminación lumínica. Por otro, el uso correcto de los LED podría ser la solución al mismo mal por su capacidad de encendido casi instantáneo.

  2. Quantitative study on morphologic features and proliferative activity during DEN-induced hepatocarcinogenesis in rats%DEN诱发大鼠肝癌变的病理形态与细胞增殖活性的定量研究

    Institute of Scientific and Technical Information of China (English)

    张新立; 史景泉; 卞修武

    2001-01-01

    目的 探讨大鼠肝癌变的形态演变和细胞增殖活性的关系。方法 通过DEN诱发启动模型和肝癌模型,采用图像分析技术,对病变细胞的形态进行测量,以PCNA和BrdU免疫组化结果反映细胞增殖活性。结果 形态测量证实卵圆细胞是一大小仅为正常肝细胞的1/8、核浆比却大6倍、形态不规则的增生小细胞;增生灶/结节嗜碱性肝细胞形态参数与肝癌细胞相似;PCNA和BrdU阳性细胞主要位于癌前增生灶及肝癌组织中;并且病变形态与细胞增殖活性有较好的一致性。结论 大鼠肝癌变的形态演变与细胞增殖活性密切相关。%Objective To explore the relationship between morphologic evolution and proliferative activity during hepatocarcinogenesis in rats. Methods Imaging analysis technique was used to detect the morphologic parameters of cells in hepatic lesions in both Solt-Farber model and diethylnitrosamine (DEN)-induced liver cancer model. Immunohistochemistry was employed to detect proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU). Results The oval cells were identified as irregular small proliferating cells in size of one-eighth of and with a nucleus/cytoplasm ratio of 6 times of the normal hepatocyte by image analysis. The morphometric parameters of basophil hepatocyte in precancerous foci and nodule were similar to those of the liver cancer cell. PCNA and BrdU positive cells were mainly localized within the proliferative foci and hepatocellular carcinoma (HCC) tissues. There was a better consistency between the development of hepatic lesions and cellular proliferative activity. Conclusion The morphologic evolution is closely related to proliferative activity during hepatocarcinogenesis in rats.

  3. PENGEMBANGAN LAMPU LED DENGAN TEKNOLOGI PHOTOVOLTAIC (LED-PV SEBAGAI ALAT BANTU PENGUMPUL IKAN PADA PERIKANAN BAGAN

    Directory of Open Access Journals (Sweden)

    Mochamad Arief Sofijanto

    2015-03-01

    mengetahui perbedaan jumlah hasil tangkapan pada bagan tancap akibat perlakuan warna lampu LED yang berbeda. Metode penelitian yang digunakan adalah deskriptif dan experimental fishing dimana rancangan penelitiannya adalah Rancangan Acak Lengkap (RAL dengan perlakuan warna lampu LED sebanyak 5 jenis warna yaitu merah (A, kuning (B, hijau (C, biru (D, dan putih (E dengan 6 kali ulangan. Secara deskriptif hasil penelitian menunjukkan lampu LED dapat digunakan untuk menggantikan lampu petromaks dan lampu LHE. Diperoleh 17 jenis ikan laut yang tertarik pada cahaya lampu LED yang digunakan. Hasil analisis statistik menunjukkan terdapat perbedaan nyata terhadap hasil tangkapan bagan dengan perlakuan warna lampu LED. Berdasarkan Uji Nyata Terkecil dinyatakan bahwa bagan yang menggunakan warna lampu LED biru mendapatkan hasil tangkapan tertinggi kemudian diikuti oleh warna kuning, hijau, putih dan merah.  The set ‘bagan’ (liftnet fishing gear is a kind of fishing gears which using atificial light as fishes gathering. This fishing gear uses an electric generator to turn on the energy saving lamp which hang on under the set ‘bagan’. The price of gasoline more expensive due to the Indonesia government’s fuel subsidy reduced and this make fishing operation costs more expensive for fishermen. This research using the LED lamps that do not use gasoline as fuel because the LED lamps can use the photovoltaic technology (solar cell system. The purposes of this study were: 1 to find out whether the LED lamps can replace the kerosene lamps and saving energy lamps, 2 to know the different in cath using different colours of LED lamps. The reserach methods are descriptive and experimental fishing which used Completely Randomized Design with LED lamps colour treatments i.e: red (A, yellow (B, green (C, blue (D, and white (E, the number of replications are 6 times. LED lamps can be used to replace the kerosene and saving energy lamps. There were 17 species of

  4. Iceland as a Model for Chemical Alteration on Mars

    Science.gov (United States)

    Bishop, J. L.; Schiffman, P.; Murad, E.; Southard, R.

    2001-03-01

    Subglacial volcanic activity on Iceland has led to the formation of a variety of silicate and iron oxide-rich alteration products that may ressemble chemical alteration on Mars. The spectral and chemical properties of Icelandic samples are presented.

  5. Adaptive filtering for white-light LED visible light communication

    Science.gov (United States)

    Hsu, Chin-Wei; Chen, Guan-Hong; Wei, Liang-Yu; Chow, Chi-Wai; Lu, I.-Cheng; Liu, Yen-Liang; Chen, Hsing-Yu; Yeh, Chien-Hung; Liu, Yang

    2017-01-01

    White-light phosphor-based light-emitting diode (LED) can be used to provide lighting and visible light communication (VLC) simultaneously. However, the long relaxation time of phosphor can reduce the modulation bandwidth and limit the VLC data rate. Recent VLC works focus on improving the LED modulation bandwidths. Here, we propose and demonstrate the use of adaptive Volterra filtering (AVF) to increase the data rate of a white-light LED VLC system. The detailed algorithm and implementation of the AVF for the VLC system have been discussed. Using our proposed electrical frontend circuit and the proposed AVF, a significant data rate enhancement to 700.68 Mbit/s is achieved after 1-m free-space transmission using a single white-light phosphor-based LED.

  6. Fluorescent silicon carbide materials for white LEDs and photovoltaics

    DEFF Research Database (Denmark)

    Syväjärvi, Mikael; Ou, Haiyan; Wellmann, Peter

    Energy efficient materials solutions will be key figures in progressive energy saving applications. We explore a materials growth concept of fluorescent wide bandgap semiconductors for white and infrared LEDs as well as solar cells. This is an emerging scientific field which has not previously been...... explored. The applications include a white LED for general lighting in which the conversion is based on the semiconductor instead of using phosphors. The result is an LED technology which does not need rare earth metals and has a pure white light. In efficient fluorescent materials, the absorption may...... the luminescence appears in the visible region which is used to produce a white LED with pure white light without need of phosphors [2]. The cubic silicon carbide polytype is challenging to master, and we have explored the growth of this crystal structure. It has a lower bandgap, and by a similar doping concept...

  7. Future Solid State Lighting using LEDs and Diode Lasers

    DEFF Research Database (Denmark)

    Petersen, Paul Michael

    2014-01-01

    significant savings. Solid state lighting (SSL) based on LEDs is today the most efficient light source for generation of high quality white light. Diode lasers, however, have the potential of being more efficient than LEDs for the generation of white light. A major advantage using diode lasers for solid state...... applications. Within the coming years, it is expected that the efficiency of blue laser diodes will approach the efficiency of infrared diode lasers. This will enable high efficiency white light generation with very high lumen per watt values. SSL today is mainly based on phosphor converted blue light emitting...... diodes (LEDs). Blue emitting 445-460 nm LED chips with conversion in phosphorescent materials have undergone tremendous development in the last decade with ultra high efficiencies. However, the technology suffers from a decrease in efficiency at high input current densities, known as the “efficiency...

  8. Effect of Led Lighting Colors for Laying Japanese Quails

    Directory of Open Access Journals (Sweden)

    KC Nunes

    Full Text Available ABSTRACT Time of exposure and light intensity rearing house may affect the performance and egg quality of laying quails. This research aimed at evaluating the live performance, egg quality, biometry of the reproductive system, and the gastrointestinal tract of Japanese quails (Coturnix coturnix japonica exposed to artificial light-emitting diodes (LED of different colors in comparison with fluorescent lamps. A total of 240 Japanese quails were distributed in completely randomized experimental design with four treatments (fluorescent lamp, and green, red, or blue LED lamps with six replicates of 10 birds each. Average egg weight and eggshell thickness were different (p0.05. The oviduct of 64-d-old hens exposed to green LED lighting was shorter (p<0.05 than those exposed to the fluorescent lamp. Red LED can be used to replace the fluorescent lamps, as they promote the same live performance, egg quality, and morphological development of the reproductive tract of laying Japanese quails.

  9. Laboratory Evaluation of LED T8 Replacement Lamp Products

    Energy Technology Data Exchange (ETDEWEB)

    Richman, Eric E.; Kinzey, Bruce R.; Miller, Naomi J.

    2011-05-23

    A report on a lab setting analysis involving LED lamps intended to directly replace T8 fluorescent lamps (4') showing light output, power, and economic comparisons with other fluorescent options.

  10. Multi-LED package design, fabrication and thermal analysis

    Institute of Scientific and Technical Information of China (English)

    R.H.Poelma; S.Tarashioon; H.W.van Zeijl; S.Goldbach; J.L.J.Zijl; G.Q.Zhang

    2013-01-01

    An ultra-thin multi-LED package is designed,manufactured and its thermal performance is characterized.The objective of this study is to develop an efficient thermal modelling approach for this system which can beused for optimization of the thermal-performance of future ultra-thin designs.A high-resolution thermal imaging camera and thermocouples were used to measure the temperature distribution of the multi-LED package and the LED-die temperature for different operating powers.Finally,we compare the thermal measurements with the finite element simulation results.It is concluded that the modelling approach can assist in the thermal optimization of future multi-LED package designs.

  11. Parent-Led Autism Therapy Shows Lasting Benefits

    Science.gov (United States)

    ... medlineplus.gov/news/fullstory_161690.html Parent-Led Autism Therapy Shows Lasting Benefits Early intervention reduced symptom ... may have lasting benefits for young children with autism, a new clinical trial suggests. Researchers from the ...

  12. Inverse design of LED arrangement for visible light communication systems

    Science.gov (United States)

    Zheng, Huanhuan; Chen, Jian; Yu, Changyuan; Gurusamy, Mohan

    2017-01-01

    In this paper, an optimal LED arrangement for indoor visible light communications (VLC) is proposed and numerically investigated. By using the concept of inverse design, the LED distribution can be formulated as a convex optimization problem and resolved accordingly. We show that sufficient brightness and uniform signal to noise ratio (SNR) can be achieved within the indoor coverage by using the proposed optimal LED arrangement, thus enabling the terminal mobility for indoor VLC. In addition, the analysis of delay spread distribution over the receiving plane shows that the design exhibits enhanced tolerance of inter-symbol interference (ISI). With the consideration of cabling cost for practical implementation, the suboptimal LED arrangement design is also investigated. Numerical results indicate that the suboptimal design can reduce the power consumption of the system with acceptable performance degradation.

  13. A Design Approach for an Innovative LED Surgical Light

    Science.gov (United States)

    Hadrath, Stefan; Morgenbrod, Nico

    2014-12-01

    We will present a design approach for a surgical light consisting of a central high-power LED module and a metal-free TIR reflector. The reflector's surface is designed as a grooved surface providing two TIR reflections.

  14. Optics designs for an innovative LED lamp family system

    Science.gov (United States)

    Weiss, Herbert; Muschaweck, Julius; Hadrath, Stefan; Kudaev, Sergey

    2011-10-01

    On the general lighting market of LED lamps for professional applications there are still mainly products for single purpose solutions existing. There is a lack of standardised lamp systems like they are common for conventional lighting technologies. Therefore, an LED lamp family system was studied using high power LED with the objective to entirely substitute standard conventional lamp families in general lighting applications in the professional market segment. This comprises the realization of sets of lamp types with compact and linear shapes as well as with light distribution characteristics ranging from diffuse to extreme collimation and exceptionally high candle power. Innovative secondary optics concepts are discussed which allow both, the design of lamps with non-bulky shape and to obtain sufficient colour mixing when using multicolour LED combinations in order to achieve a very high colour rendering quality.

  15. Medical students' learning from patient-led teaching

    DEFF Research Database (Denmark)

    Henriksen, Ann-Helen; Ringsted, Charlotte

    2014-01-01

    The aim of this study was to explore how medical students perceive the experience of learning from patient instructors (patients with rheumatism who teach health professionals and students) in the context of coupled faculty-led and patient-led teaching session. This was an explorative study...... a patient-centred approach, and acknowledged the importance of the PIs' individual perspectives and experiential knowledge. On the other hand, representing the scientific biomedical perspective and traditional step-by step teaching, students expressed unfamiliarity with the unstructured experiential...... learning and scepticism regarding the credibility of the patients' knowledge. This study contributes to the understanding of the complexity of involving patients as teachers in healthcare education and initiates a discussion on how to complement faculty-led teaching with patient-led teaching involving...

  16. LED lamp incorporating remote phosphor with heat dissipation features

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Tao; Letoquin, Ronan; Keller, Bernd; Tarsa, Eric

    2016-11-22

    An LED lamp or bulb is disclosed that comprises a light source, a heat sink structure and a remote planar phosphor carrier having at least one conversion material. The phosphor carrier can be remote to the light sources and mounted to the heat sink so that heat from the phosphor carrier spreads into the heat sink. The phosphor carrier can comprise a thermally conductive transparent material and a phosphor layer, with an LED based light source mounted to the heat sink such that light from the light source passes through the phosphor carrier. At least some of the LED light is converted by the phosphor carrier, with some lamp embodiments emitting a white light combination of LED and phosphor light. The phosphor arranged according to the present invention can operate at lower temperature to thereby operate at greater phosphor conversion efficiency and with reduced heat related damage to the phosphor.

  17. Optimized Design of LED Daylight Lamp Lighting System

    Institute of Scientific and Technical Information of China (English)

    TIAN Da-lei; GUAN Rong-feng; WANG Xing

    2008-01-01

    In order to meet the requirements of indoor illumination, a LED daylight lamp model was designed, it can replace traditional fluorescent lamp without insteading additional power supply establishment. The optical properties of the model were simulated using optical analysis software. Its luminous efficiency is about 30.4 lm/W, and the illuminance is about 38 lux when the distance is 1.5 m between the center of the model and measured spot. With the theoretically-optimized design of LED model, experiments based on the results of the optimal simulation in the laboratory were conducted to verify the performance of the proposed LED model, it reaches a power factor of about 0.8 at 6 W. The simulation results are very similar with the measured values. It is testified that simulative method is one of the effective tools for LED lighting optical design.

  18. On the spectral quality of scanner illumination with LEDs

    Science.gov (United States)

    Cui, Chengwu

    2013-01-01

    Document scanner illumination has evolved along with general illumination technologies. LEDs have become more and more popular as the illumination sources for document scanning. LED technologies provide a wide range of choices both in terms of structural design and spectral compositions. In this report, we examine some popular LED technologies used for document scanner. We evaluate the color rendering performance of scanner models with different illumination technologies by examining their rendering of the Macbeth ColorChecker™ in sRGB. We found that more phosphors in phosphor conversion types of white LEDs may not be necessarily advantageous in terms of scanner color rendering performance. Also CIS type of scanner may be sensitive to the peak wavelength shift and can be particularly problematic when the peaks are out of certain range.

  19. LEDs Illuminate Bulbs for Better Sleep, Wake Cycles

    Science.gov (United States)

    2015-01-01

    Life on the International Space Station (ISS) wreaks havoc on an astronaut’s biological rhythms, and one way NASA mitigates the problem is through the use of LED lighting to alternately stimulate energy and focus and induce relaxation. Satellite Beach, Florida-based Lighting Science partnered with Kennedy Space Center to commercialize an LED system designed for the ISS, resulting in its DefinityDigital product line of light bulbs now used in numerous homes, hotel chains, and resorts.

  20. Two phase interleaved buck converter for driving high power LEDs

    DEFF Research Database (Denmark)

    Beczkowski, Szymon; Munk-Nielsen, Stig

    2011-01-01

    increases luminous efficacy of LED compared to PWM dimmed system. Because of the low dynamic resistance of LEDs the duty cycle of the converter does not change greatly with controlled current. By setting the input voltage of the buck converter to around twice the voltage of diode strings, converter can...... be operated close to the 50% duty cycle, where the ripple attenuation is the highest....

  1. Heat Transfer Characteristics in High Power LED Packaging

    OpenAIRE

    Chi-Hung Chung; Kai-Shing Yang; Kuo-Hsiang Chien; Ming-Shan Jeng; Ming-Tsang Lee

    2014-01-01

    This study uses the T3Ster transient thermal resistance measuring device to investigate the effects to heat transfer performances from different LED crystal grains, packaging methods and heat-sink substrates through the experimental method. The experimental parameters are six different types of LED modules that are made alternatively with the crystal grain structure, the die attach method and the carrying substrate. The crystal grain structure includes the lateral type, flip chip type and ver...

  2. Integrated LED-based luminaire for general lighting

    Energy Technology Data Exchange (ETDEWEB)

    Dowling, Kevin J.; Lys, Ihor A.; Williamson, Ryan C.; Roberge, Brian; Roberts, Ron; Morgan, Frederick; Datta, Michael Jay; Mollnow, Tomas Jonathan

    2016-08-30

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  3. Biological Research in Canisters (BRIC) - Light Emitting Diode (LED)

    Science.gov (United States)

    Levine, Howard G.; Caron, Allison

    2016-01-01

    The Biological Research in Canisters - LED (BRIC-LED) is a biological research system that is being designed to complement the capabilities of the existing BRIC-Petri Dish Fixation Unit (PDFU) for the Space Life and Physical Sciences (SLPS) Program. A diverse range of organisms can be supported, including plant seedlings, callus cultures, Caenorhabditis elegans, microbes, and others. In the event of a launch scrub, the entire assembly can be replaced with an identical back-up unit containing freshly loaded specimens.

  4. Design of 25-inch Direct Illumination-type LED Backlight

    Institute of Scientific and Technical Information of China (English)

    LIANG Bao-wen; LI Rong-yu; GUO Ying-ying; WANG Shuai; CHEN Xiu-jin

    2008-01-01

    We utilized "direct illumination-type" LED backlight project, made white-light LED array in rectangle, designed a sheet of reflective film, a sheet of diffuser and two sheets of brightness enhancement film, then analyzed illuminance chart which was the result of simulation in several distance between reflective film and optical film. It showed the best matching between illuminance and uniformity while in 25 mm distance. Finally, we discussed some problems with thermal dispersion.

  5. Optimal colour quality of LED clusters based on memory colours.

    Science.gov (United States)

    Smet, Kevin; Ryckaert, Wouter R; Pointer, Michael R; Deconinck, Geert; Hanselaer, Peter

    2011-03-28

    The spectral power distributions of tri- and tetrachromatic clusters of Light-Emitting-Diodes, composed of simulated and commercially available LEDs, were optimized with a genetic algorithm to maximize the luminous efficacy of radiation and the colour quality as assessed by the memory colour quality metric developed by the authors. The trade-off of the colour quality as assessed by the memory colour metric and the luminous efficacy of radiation was investigated by calculating the Pareto optimal front using the NSGA-II genetic algorithm. Optimal peak wavelengths and spectral widths of the LEDs were derived, and over half of them were found to be close to Thornton's prime colours. The Pareto optimal fronts of real LED clusters were always found to be smaller than those of the simulated clusters. The effect of binning on designing a real LED cluster was investigated and was found to be quite large. Finally, a real LED cluster of commercially available AlGaInP, InGaN and phosphor white LEDs was optimized to obtain a higher score on memory colour quality scale than its corresponding CIE reference illuminant.

  6. UV-LEDs Efficiently Inactivate DNA and RNA Coliphages

    Directory of Open Access Journals (Sweden)

    Alyaa M. Zyara

    2017-01-01

    Full Text Available UV-LEDs are a new method of disinfecting drinking water. Some viruses are very resistant to UV and the efficiency of UV-LEDs to disinfect them needs to be studied. Drinking water was disinfected with UV-LEDs after spiking the water with MS2 and four UV- and/or Cl-resistant coliphages belonging to RNA or DNA coliphages isolated from municipal wastewater. UV-LEDs operating at a wavelength of 270 nm for 2 min with 120 mW of irradiation caused 0.93–2.73 Log10-reductions of coliphages tested in a reactor of a 5.2 L volume. Irradiation time of 10 min in the same system increased the Log10-reductions to 4.30–5.16. Traditional mercury UV (Hg-UV lamp at a 254 nm wavelength caused 0.67–4.08 Log10-reductions in 2 min and 4.56–7.21 Log10-reductions in 10 min in 10 mL of water. All coliphages tested except MS2 achieved 4 Log10-reductions with UV-LEDs at a dose that corresponded to 70 mWs/cm2 using Hg-UV. Thus, UV-LEDs are a promising method of disinfecting UV- and/or Cl-resistant viruses.

  7. III-nitride monolithic LED covering full RGB color gamut

    Science.gov (United States)

    El-Ghoroury, Hussein S.; Chuang, Chih-Li; Kisin, Mikhail V.

    2016-03-01

    We present numerical simulation of III-nitride monolithic multi-color LED covering full red-green-blue (RGB) color gamut. The RGB LED structure was grown at Ostendo Technologies Inc. and has been used in Ostendo proprietary Quantum Photonic Imager (QPI) device. Active region of our RGB LED incorporates specially designed intermediate carrier blocking layers (ICBLs) controlling transport of each type of carriers and subsequent carrier injection redistribution among the optically active quantum wells (QWs) with different emission wavelengths. ICBLs are proved to be essential elements of multi-color LED active region design requiring optimization both in material composition and doping level. Strong interdependence between ICBL parameters and active QW characteristics presents additional challenge to multi-color LED design. Combination of several effects was crucial for adequate simulation of RGB LED color control features. Standard drift-diffusion transport model has been appended with rate equations for dynamic QW-confined carrier populations which appear severely off-balanced from corresponding mobile carrier subsystems. QW overshoot and Auger-assisted QW depopulation were also included into the carrier kinetic model thus enhancing the non-equilibrium character of QW confined populations and supporting the mobile carrier transport across the MQW active region. For device simulation we use COMSOL-based program suit developed at Ostendo Technologies Inc.

  8. Infrared imaging of LED lighting tubes and fluorescent tubes

    Science.gov (United States)

    Siikanen, Sami; Kivi, Sini; Kauppinen, Timo; Juuti, Mikko

    2011-05-01

    The low energy efficiency of conventional light sources is mainly caused by generation of waste heat. We used infrared (IR) imaging in order to monitor the heating of both LED tube luminaires and ordinary T8 fluorescent tubes. The IR images showed clearly how the surface temperatures of the fluorescent tube ends quickly rose up to about +50...+70°C, whereas the highest surface temperatures seen on the LED tubes were only about +30...+40°C. The IR images demonstrated how the heat produced by the individual LED chips can be efficiently guided to the supporting structure in order to keep the LED emitters cool and hence maintain efficient operation. The consumed electrical power and produced illuminance were also recorded during 24 hour measurements. In order to assess the total luminous efficacy of the luminaires, separate luminous flux measurements were made in a large integrating sphere. The currently available LED tubes showed efficacies of up to 88 lm/W, whereas a standard "cool white" T8 fluorescent tube produced ca. 75 lm/W. Both lamp types gave ca. 110 - 130 lx right below the ceiling-mounted luminaire, but the LED tubes consume only 40 - 55% of the electric power compared to fluorescent tubes.

  9. LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

    Directory of Open Access Journals (Sweden)

    SK. S. Rahman

    2014-07-01

    Full Text Available We demonstrate the strong influence of GaN substrate surface morphology on optical properties and performance of light emitting devices grown on freestanding GaN. As-grown freestanding HVPE GaN substrates show excellent AFM RMS and XRD FWHM values over the whole area, but distinctive features were observed on the surface, such as macro-pits, hillocks and facets extending over several millimeters. Electroluminescence measurements reveal a strong correlation of the performance and peak emission wavelength of LEDs with each of these observed surface features. This results in multiple peaks and non-uniform optical output power for LEDs on as-grown freestanding GaN substrates. Removal of these surface features by chemical mechanical polishing results in highly uniform peak wavelength and improved output power over the whole wafer area.

  10. Low-noise moisture meter with high-speed LED techniques

    Science.gov (United States)

    Aikio, Rami; Lindström, Hannu; Suopajärvi, Pekka; Malinen, Jouko; Mäntylä, Markku

    2010-04-01

    Near infrared (NIR) spectroscopy can provide inexpensive, rapid and contact-free chemical content measurements for on-line, hand-held and laboratory applications. Traditionally multiwavelength NIR analyzers are based on incandescent lamp light sources with rotating filter wheels, even though designs relying on lamp technology and moving parts mean larger size, require frequent maintenance and eventually limit measurement speed of the system. Today, optical power and available wavelength range of LEDs enable their use in chemical content analyzers. In this publication, a paper moisture meter with high speed LED techniques is presented. A prototype developed at VTT utilizes an extended InGaAs detector to measure diffuse reflection at four NIR wavelengths ranging from 1.2 to 2.1 μm. Source LED currents are amplitude modulated with fixed sinusoidal frequencies. Optical signals at each wavelength are demodulated from the detector signal using real-time digital lock-in detection method on an FPGA. Moisture content is calculated and displayed on the embedded platform. The design allows very high speed operation, where the result is updated every 1 ms. Performance of the prototype system was studied by measuring a set of known sealed paper samples. Paper moisture measurement accuracy was 0.14, repeatability 0.01 and 2σ noise 0.04 moisture percent. Laboratory tests showed that channel crosstalk after detection is below background noise level. The measured signal-to-noise ratios per channel were 70 - 85 dB when all LEDs were on. The overall performance equals the level of incandescent lamp based on-line moisture meters currently in use in paper mill and process automation. The developed system forms a good basis also for other content measurements.

  11. Current State of the Art in High Brightness LEDs

    Science.gov (United States)

    Craford, George

    2007-03-01

    LED's have been commercially available since the 1960's. For many years they were used primarily for indicator applications. The remarkable increase in materials technology and efficiency that has been achieved since the early 1990's for AlInGaP red and amber LEDs, and InGaN green and blue LEDs, has enabled the penetration of markets such as outdoor display, signaling, and automotive brake light and turn signal applications. White LEDs, which are either blue LEDs combined with a phosphor, or a combination of red, green, and blue LEDs, are being used in emerging applications such as cell phone flash, television backlights, projection, and automotive headlights. In addition, to efficiency improvements these applications have required the development of higher power packages and, in some of these applications which are etendue limited, higher luminance devices. High power devices are commercially available which are capable of 140 lumens output and have an efficacy of around 70 lm/W for white emission. New package and chip technologies have been demonstrated which have a luminance of 38 mega nits (Mcd/m^2), approximately 50% more luminance than that of an automotive headlamp halogen bulb (˜25 mega nits). The recent progress in materials technology, packaging, and chip technology makes it clear that LED's will become important for general illumination applications. The rate of LED penetration of this market will depend upon continued increases in performance and lower costs as well as better control of the white spectral emission. Efficiency, current density, and costs are closely linked because the cost in dollars/lumen is inversely proportional to how many lumens can be realized from each unit of device area for a given device type. Performance as high as 138 lm/W, and over 40% wall plug efficiency, has been reported for low power research devices and over 90 lm/W for high power research devices. It is clear that high power commercial products with performance in

  12. Verbaalne soolo Jaanus Nõgistolt : Led R-ist, Narva Linna Sümfooniaorkestrist ja Led Zeppelinist / Jaanus Nõgisto ; interv. Margo Pajuste

    Index Scriptorium Estoniae

    Nõgisto, Jaanus, 1956-

    2007-01-01

    Rockansambli Led Zeppelini muusikast, ansamblist Led R ja heliplaadist "Led the R Out" räägib kitarrist Jaanus Nõgisto. Led R ja Narva Linna Sümfooniaorkestri kontserdid: 22. juunil Pärnus ja 14. juulil Haapsalu lossihoovis, ansambli Led R kontsert koos Havana Blackiga 3. aug. Sõru sadamas Hiiumaal

  13. In vitro inactivation of Enterococcus faecalis with a led device.

    Science.gov (United States)

    D'Ercole, S; Spoto, G; Trentini, P; Tripodi, D; Petrini, M

    2016-07-01

    Non-coherent light-emitting diodes (LEDs) are effective in a large variety of clinical indications; however, the bactericidal activity of LEDs is unclear, although the effectiveness of such lights is well known. Currently, no studies have examined the effects of NIR-LED on bacteria. The aims of this study were to verify the antibacterial activity of 880-nm LED irradiation on a bacterial suspension of Enterococcus faecalis and to compare it with the actions of sodium hypochlorite (NaOCl) and the concurrent use of both treatments. Before we proceeded with the main experiment, we first performed preliminary tests to evaluate the influence of such parameters as the distance of irradiation, the energy density, the irradiation time and the presence of photosensitizers on the antimicrobial effects of LEDs. After treatment, the colony forming units per milliliter (CFU/mL) was recorded and the data were submitted to ANOVA and Bonferroni post hoc tests at a level of significance of 5%. The results showed that LED irradiation, at the parameters used, is able to significantly decrease E. faecalis viability in vitro. The total inhibition of E. faecalis was obtained throughout concurrent treatment of LED and NaOCl (1%) for 5min. The same antimicrobial activity was confirmed in all of the experiments (p<0.05), but no statistically significant differences were found by varying such parameters as the distance of irradiation (from 0.5mm to 10mm), energy density (from 2.37 to 8.15mJ/s), irradiation time (from 5min to 20min) or by adding toluidine blue O (TBO).

  14. Highly Efficient Small Form Factor LED Retrofit Lamp

    Energy Technology Data Exchange (ETDEWEB)

    Steven Allen; Fred Palmer; Ming Li

    2011-09-11

    This report summarizes work to develop a high efficiency LED-based MR16 lamp downlight at OSRAM SYLVANIA under US Department of Energy contract DE-EE0000611. A new multichip LED package, electronic driver, and reflector optic were developed for these lamps. At steady-state, the lamp luminous flux was 409 lumens (lm), luminous efficacy of 87 lumens per watt (LPW), CRI (Ra) of 87, and R9 of 85 at a correlated color temperature (CCT) of 3285K. The LED alone achieved 120 lumens per watt efficacy and 600 lumen flux output at 25 C. The driver had 90% electrical conversion efficiency while maintaining excellent power quality with power factor >0.90 at a power of only 5 watts. Compared to similar existing MR16 lamps using LED sources, these lamps had much higher efficacy and color quality. The objective of this work was to demonstrate a LED-based MR16 retrofit lamp for replacement of 35W halogen MR16 lamps having (1) luminous flux of 500 lumens, (2) luminous efficacy of 100 lumens per watt, (3) beam angle less than 40{sup o} and center beam candlepower of at least 1000 candelas, and (4) excellent color quality.

  15. Optical design of LED-based automotive tail lamps

    Science.gov (United States)

    Domhardt, André; Rohlfing, Udo; Klinger, Karsten; Manz, Karl; Kooß, Dieter; Lemmer, Uli

    2007-09-01

    The application of ultra bright monochromatic and white High-Power-LEDs in the range of automotive lighting systems is now state of the art. These LEDs offer new possibilities in optical design and engineering within different fields of automotive lighting, e.g., tail lamps, signal lamps, headlamps and interior lighting. This contribution describes the process of the optical design of an automotive LED tail lamp based on a practical example. We will elaborate the principal geometric approach, the radiometric conditions and the optical design by using standard and advanced mathematical optimization methods. Special attention will be paid to the following topics: efficient light coupling from the LED into the optical device, adaptation of the illuminance and optimization with respect to the requirements from SAE/ECE regulations. It will be shown that the development of LED-lamps requires the complex interaction of several factors. The challenge for the optical designer is to fulfill the technical demands while also considering the appearance of the final product desired by the customer. Further design specifications emerge from the electrical and thermal layout of the lamp.

  16. LED Monitoring System of the Phenix Muon Piston Calorimeter

    Science.gov (United States)

    Motschwiller, Steven

    2010-11-01

    The Muon Piston Calorimeter in the PHENIX experiment at RHIC has a monitoring system consisting of LEDs and PIN diodes to calibrate out the time dependent changes to the detector. The LEDs track the temperature and radiation-damage changes to the response of the MPC, while the absolute calibration can be done using 0̂ decays. To execute this, LEDs flash light through the PbWO4 crystal to the Avalanche Photo Diodes The MPC is made up of 416 independent electromagnetic calorimeter towers. By using the LEDs we can correct for changes in the gains of each tower in the MPC, on a run by run basis. Because the LED value only gives a relative measurement of the gain over time, this method of calibration can only be used in conjunction with absolute calibrations provided by 0̂ decays or by minimum ionizing peaks . This work will be used to make a final measurement on Transverse energy at √sNN = 200 GV in Au+Au collisions.

  17. Color Maintenance of LEDs in Laboratory and Field Applications

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Tuttle, Ralph; Rosenfeld, Scott M.; Miller, Naomi J.

    2013-09-30

    Synopsis: To date, consideration for parametric failure of LED products has largely been focused on lumen maintenance. However, color shift is a cause of early failure for some products, and is especially important to consider in certain applications, like museums, where visual appearance is critical. Example data collected by the GATEWAY program for LED lamps installed in museums shows that many have changed color beyond a reasonable tolerance well before their rated lifetime was reached, necessitating replacement. Similar data collected by the CALiPER program between 2008 and 2010 reveals that many early products shifted beyond acceptable tolerances in as little as a few thousand hours. In contrast, data from the L Prize program illustrates that commercially available LED products can have exemplary color stability that is unmatched by traditional light sources. Beyond presenting data from the aforementioned DOE programs, this report discusses the metrics used for communicating color shift—namely MacAdam ellipses and Δu'v'—as well as providing guidance for end users on how to monitor color shift and what to look for in manufacturer warranties. Also included are descriptions of the physical changes that have been documented as leading to color shift in some example types of LED packages. As with complete products, the data presented herein for LED packages shows that a wide variety of products are available; in order for specifiers and consumers to make educated choices, more detailed and standardized information should be made available.

  18. Colorimetry and efficiency of white LEDs: Spectral width dependence

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Elaine; Edwards, Paul R.; Martin, Robert W. [Department of Physics, SUPA, Strathclyde University, Glasgow (United Kingdom)

    2012-03-15

    The potential colour rendering capability and efficiency of white LEDs constructed by a combination of individual red, green and blue (RGB) LEDs are analysed. The conventional measurement of colour rendering quality, the colour rendering index (CRI), is used as well as a recently proposed colour quality scale (CQS), designed to overcome some of the limitations of CRI when narrow-band emitters are being studied. The colour rendering performance is maximised by variation of the peak emission wavelength and relative intensity of the component LEDs, with the constraint that the spectral widths follow those measured in actual devices. The highest CRI achieved is 89.5, corresponding to a CQS value of 79, colour temperature of 3800 K and a luminous efficacy of radiation (LER) of 365 lm/W. By allowing the spectral width of the green LED to vary the CRI can be raised to 90.9, giving values of 82.5 and 370 lm/W for the CQS and LER, respectively. The significance of these values are discussed in terms of optimising the possible performance of RGB LEDs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Status and prospects for phosphor-based white LED packaging

    Institute of Scientific and Technical Information of China (English)

    Zongyuan LIU; Sheng LIU; Kai WANG; Xiaobing LUO

    2009-01-01

    The status and prospects for high-power, phosphor-based white light-emitting diode (LED) pack-aging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (COB) technology with a multi-layer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SIP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

  20. Blue laser diode (LD) and light emitting diode (LED) applications

    Science.gov (United States)

    Bergh, Arpad A.

    2004-09-01

    The family of blue LEDs, edge emitting and surface emitting lasers, enable a number of applications. Blue lasers are used in digital applications such as optical storage in high density DVDs. The resolution of the spot size and hence the storage density is diffraction limited and is inversely proportional to the square of the wavelength of the laser. Other applications include printing, optical scanners, and high-resolution photo-lithography.As light emitters, blue LEDs are used for signaling and in direct view large area emissive displays. They are also making inroads into signage and LCD back-lighting, mobile platforms, and decorative accent lighting in curtains, furniture, etc.Blue LEDs produce white light either with phosphor wavelength converters or in combination with red and green LEDs. The full potential of LED light sources will require three devices to enable complete control over color and intensity.Sensing and medical/bio applications have a major impact on home security, on monitoring the environment, and on health care. New emerging diagnostic and therapeutic applications will improve the quality and reduce the cost of health care.

  1. Aerial LED signage by use of crossed-mirror array

    Science.gov (United States)

    Yamamoto, Hirotsugu; Kujime, Ryousuke; Bando, Hiroki; Suyama, Shiro

    2013-03-01

    3D representation of digital signage improves its significance and rapid notification of important points. Real 3D display techniques such as volumetric 3D displays are effective for use of 3D for public signs because it provides not only binocular disparity but also motion parallax and other cues, which will give 3D impression even people with abnormal binocular vision. Our goal is to realize aerial 3D LED signs. We have specially designed and fabricated a reflective optical device to form an aerial image of LEDs with a wide field angle. The developed reflective optical device composed of crossed-mirror array (CMA). CMA contains dihedral corner reflectors at each aperture. After double reflection, light rays emitted from an LED will converge into the corresponding image point. The depth between LED lamps is represented in the same depth in the floating 3D image. Floating image of LEDs was formed in wide range of incident angle with a peak reflectance at 35 deg. The image size of focused beam (point spread function) agreed to the apparent aperture size.

  2. LED-ID System: Coverage And Fast Link Recovery Technique

    Directory of Open Access Journals (Sweden)

    Muhammad Shahin Uddin

    2012-11-01

    Full Text Available Recently Light Emitting Diodes (LEDs are considered to represent the next generation of lighting and communication technology. LED-ID (Light Emitting Diode – Identification is one of the key technologies for identification, data transmission and illumination simultaneously. This is the new paradigm in theidentification technology environment. LED-ID system typically needs line of sight (LOS to support narrow FOV transceivers links to achieve high data rate but reduced the coverage, increase the disconnection rate of the link. Also when the receiver moves horizontally or vertically, in that case coverage also varied and LOS relies upon direct link between transmitter and receiver. Link recovery is a new challenge for reliable LED-ID system. Fast link recovery techniques are essential for the making the system robust. In this paper we discuss about the horizontal and vertical coverage variation in terms of received power and fast link recovery technique for the LED-ID system considering both LOS and NLOS reflection.

  3. Semiconductor lasers vs LEDs in diagnostic and therapeutic medicine

    Science.gov (United States)

    Gryko, Lukasz; Zajac, Andrzej; Szymanska, Justyna; Blaszczak, Urszula; Palkowska, Anna; Kulesza, Ewa

    2016-12-01

    Semiconductor emitters are used in many areas of medicine, allowing for new methods of diagnosis, treatment and effective prevention of many diseases. The article presents selected areas of application of semiconductor sources in UVVIS- NIR range, where in recent years competition in semiconductor lasers and LEDs applications has been observed. Examples of applications of analyzed sources are indicated for LLLT, PDT and optical diagnostics using the procedure of color contrast. Selected results of LLLT research of the authors are presented that were obtained by means of the developed optoelectronic system for objectified irradiation and studies on the impact of low-energy laser and LED on lines of endothelial cells of umbilical vein. Usefulness of the spectrally tunable LED lighting system for diagnostic purposes is also demonstrated, also as an illuminator for surface applications - in procedure of variable color contrast of the illuminated object.

  4. Developing a nurse-led clinic using transformational leadership.

    Science.gov (United States)

    Gousy, Mamood; Green, Kim

    2015-03-25

    Nurses are at the forefront of implementing and managing change, given constantly changing healthcare services and the increase in demand for health care. Therefore, it is important to identify the best style of leadership to engage nurses in implementing service-led improvements. This article explores the effects of transformational leadership in bringing about service-led improvements in health care, using the example of setting up a nurse-led acupuncture clinic to optimise the care of patients with chronic pain. Transformational leadership was used throughout the project - from the initial local planning, training and development, through to liaising with the appropriate staff and deciding on an evaluation strategy. Transformational leadership proved to be an effective way to engage and empower nurses and other members of the chronic pain team to enable them to achieve the project aims.

  5. Inorganic phosphors in lead-silicate glass for white LEDs

    Science.gov (United States)

    Nikonorov, N. V.; Kolobkova, E. V.; Aseev, V. A.; Bibik, A. Yu.; Nekrasova, Ya. A.; Tuzova, Yu. V.; Novogran, A. I.

    2016-09-01

    Luminescent composites of the "phosphor-in-glass" type, based on a highly reflective lead-silicate matrix and fine-grained powders of YAG:Ce3+ and SiAlON:Eu2+ crystals, are developed and synthesized. Phosphor and glass powders are sintered at a temperature of 550°C to obtain phosphor samples for white LEDs. The composites are analyzed by X-ray diffraction and luminescence spectroscopy. The dependence of the light quantum yield on the SiAlON:Eu2+ content in the samples is investigated. A breadboard of a white LED is designed using a phosphor-in-glass composite based on lead-silicate glass with a low glasstransition temperature. The total emission spectra of a blue LED and glass-based composites are measured. The possibility of generating warm white light by choosing an appropriate composition is demonstrated.

  6. Control and Driving Methods for LED Based Intelligent Light Sources

    DEFF Research Database (Denmark)

    Beczkowski, Szymon

    High power light-emitting diodes allow the creation of luminaires capable of generating saturated colour light at very high efficacies. Contrary to traditional light sources like incandescent and high-intensity discharge lamps, where colour is generated using filters, LEDs use additive light mixing......, where the intensity of each primary colour diode has to be adjusted to the needed intensity to generate specified colour. The function of LED driver is to supply the diode with power needed to achieve the desired intensity. Typically, the drivers operate as a current source and the intensity...... of the diode is controlled either by varying the magnitude of the current or by driving the LED with a pulsed current and regulate the width of the pulse. It has been shown previously, that these two methods yield different effects on diode's efficacy and colour point. A hybrid dimming strategy has been...

  7. Self-aligning LED-based optical link

    Science.gov (United States)

    Shen, Thomas C.; Drost, Robert J.; Rzasa, John R.; Sadler, Brian M.; Davis, Christopher C.

    2016-09-01

    The steady advances in light-emitting diode (LED) technology have motivated the use of LEDs in optical wireless communication (OWC) applications such as indoor local area networks (LANs) and communication between mobile platforms (e.g., robots, vehicles). In contrast to traditional radio frequency (RF) wireless communication, OWC utilizes electromagnetic spectrum that is largely unregulated and unrestricted. OWC communication may be especially useful in RF-denied environments, in which RF communication may be prohibited or undesirable. However, OWC does present some challenges, including the need to maintain alignment between potentially moving nodes. We describe a novel system for link alignment that is composed of a hyperboloidal mirror, camera, and gimbal. The experimental system is able to use the mirror and camera to detect an LED beacon of a neighboring node and estimate its bearing (azimuth and elevation), point the gimbal towards the beacon, and establish an optical link.

  8. InGaN/GaN Nanowire LEDs and Lasers

    KAUST Repository

    Zhao, Chao

    2016-01-01

    The large specific surface, and the associated high density of surface states was found to limit the light output power and quantum efficiency of nanowire-array devices, despite their potential for addressing the “green-gap” and efficiency-droop issues. The phonon and carrier confinement in nanowires also led to junction heating, and reduced heat dissipation. In this paper, we will present our studies on effective surface states passivation in InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) and lasers grown on silicon (Si), as well as our recent work on nanowires LEDs grown on bulk-metal, a non-conventional substrate.

  9. Evaluation of a nurse-led haemophilia counselling service.

    Science.gov (United States)

    O'Shea, Eadaoln; Coughlan, Michael; Corrigan, Helen; McKee, Gabrielle

    Genetic counselling and testing for females with a family history of haemophilia has long been advocated. However, there is little research in regard to clients' satisfaction with the existing counselling models in haemophilia, and in particular with nurse-led clinics. The purpose of this study was to evaluate whether clients were satisfied with a nurse-led carrier testing clinic and counselling service. A retrospective quantitative study of clients' satisfaction and perceived knowledge was undertaken using an anonymous questionnaire. A sample of 42 women who had attended the clinic in the last 12 months was identified. The response rate for the study was 71% (n = 30).Two thirds of the respondents were 35 years of age or younger, 93% had a family history of haemophilia and 56% were diagnosed as carriers. Perceived understanding and knowledge increased significantly between the first and second appointments (p nurse-led carrier testing clinic and counselling service.

  10. Novel chip coating approaches to improve white LED technology

    Science.gov (United States)

    Hartmann, Paul; Schweighart, Marko; Sommer, Christian; Wenzl, Franz-P.; Zinterl, Ernst; Hoschopf, Hans; Pachler, Peter; Tasch, Stefan

    2008-02-01

    Key market requirements for white LEDs, especially in the general lighting and automotive headlamp segments call for improved concepts and performance of white LEDs based on phosphor conversion. Major challenges are small emission areas, highest possible intensities, long-term color stability, and spatial homogeneity of color coordinates. On the other hand, the increasingly high radiation power of the blue LEDs poses problems for all involved materials. Various thick film coating technologies are widely used for applying the color conversion layer to the semiconductor chip. We present novel concepts based on Silicate phosphors with high performance in terms of spatial homogeneity of the emission and variability of the color temperature. Numerical calculation of the optical properties with the help of state-of-the-art simulation tools was used as a basis for the practical optimization of the layer geometries.

  11. Evaluation of OLED and edge-lit LED lighting panels

    Science.gov (United States)

    Mou, Xi; Narendran, Nadarajah; Zhu, Yiting; Freyssinier, Jean Paul

    2016-09-01

    Solid-state lighting (SSL) offers a new technology platform for lighting designers and end-users to illuminate spaces with low energy demand. Two types of SSL sources include organic light-emitting diodes (OLEDs) and light-emitting diodes (LEDs). OLED is an area light source, and its primary competing technology is the edge-lit LED panel. Generally, both of these technologies are considered similar in shape and appearance, but there is little understanding of how people perceive discomfort glare from large area light sources. The objective of this study was to evaluate discomfort glare for the two lighting technologies under similar operating conditions by gathering observers' reactions. The human factors study results showed no statistically significant difference in human response to discomfort glare between OLED and edge-lit LED panels when the two light sources produced the same lighting stimulus. This means both technologies appeared equally glary beyond a certain luminance.

  12. Markets and technology needs for UHB-LEDs

    Science.gov (United States)

    Roussel, Philippe

    2007-09-01

    With an annual volume of more than 5 million units of 2" equivalent substrates, GaN-based LED is the main eater of nitride materials targeting a 3.5B market at devices level. The next big challenge for LED business is to take market shares over the general lighting industry and dollar per lumen (/lm) ratio is the key parameter. Numerous technological improvements are under investigation: - At die level, photonic crystals and surface texturing technologies are jointly developed to increase the light extraction. External Quantum Efficiency EQE has now reached > 75% at R&D level. - At material level, there is a rapid emergence of new substrates for GaN epitaxy and composite substrates in 6" diameter. That is opening new doors to higher LED luminous efficiency and cost reduction toward the gigantic SSL general illumination business.

  13. A thermosyphon heat pipe cooler for high power LEDs cooling

    Science.gov (United States)

    Li, Ji; Tian, Wenkai; Lv, Lucang

    2016-08-01

    Light emitting diode (LED) cooling is facing the challenge of high heat flux more seriously with the increase of input power and diode density. The proposed unique thermosyphon heat pipe heat sink is particularly suitable for cooling of high power density LED chips and other electronics, which has a heat dissipation potential of up to 280 W within an area of 20 mm × 22 mm (>60 W/cm2) under natural air convection. Meanwhile, a thorough visualization investigation was carried out to explore the two phase flow characteristics in the proposed thermosyphon heat pipe. Implementing this novel thermosyphon heat pipe heat sink in the cooling of a commercial 100 W LED integrated chip, a very low apparent thermal resistance of 0.34 K/W was obtained under natural air convection with the aid of the enhanced boiling heat transfer at the evaporation side and the enhanced natural air convection at the condensation side.

  14. Study on the p-type QWIP-LED device

    Institute of Scientific and Technical Information of China (English)

    ZHEN; Honglou; XIONG; Dayuan; ZHOU; Xuchang; LI; Ning; SHAO; Jun; LU; Wei

    2006-01-01

    A p-type quantum well infrared photodetector (QWIP) integrated with a light-emitting diode (LED) (named QWIP-LED) was fabricated and studied. The infrared photo-response spectrum was obtained from the device resistance variation and the near-infrared photo-emission intensity variation. A good agreement between these two spectra was observed, which demonstrates that the long-wavelength infrared radiation around 7.5 μm has been transferred to the near-infrared light at 0.8 μm by the photo-electronic process in the QWIP-LED structure. Moreover, the experimentally observed infrared response wavelength is in good agreement with the theoretical calculation value of 7.7 μm. The results on the upconversion of the infrared radiation will be very useful for the new infrared focal plane array technology.

  15. Analyzing of LED-induced Blood Fluorescent Spectra

    Institute of Scientific and Technical Information of China (English)

    高淑梅; 骆晓森; 兰秀风; 刘莹; 陆健; 倪晓武

    2002-01-01

    The visible fluorescence spectra of healthy mice blood cells have been measured by light emitting diode (LED) excitation at about 570 nm (Δλ1/2≈32 nm ) in vitro. It is found that the spectral profiles of mouse blood, erythrocyte and hemoglobin are similar. The physical mechanism for LED-induced blood cells fluorescence spectra is analyzed. The development of low intensity laser or light irradiating blood therapy in vivo and in vitro may be guided by the understanding of blood fluorescence characteristics.

  16. High quality Danish design with intelligent LED light. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Paul Michael; Dam-Hansen, C.; Thestrup, B.; Pedersen, Henrik (Technical Univ. of Denmark, DTU Fotonik, Roskilde (Denmark)); Olsen, Jesper (JesperOlsen ApS, Frederiksberg (Denmark)); Falleboe, H.; Andersen, Jakob (MORFOSO, Copenhagen (Denmark))

    2010-02-15

    Based on the results achieved in a previous project, which enabled a number of designers to be trained in the potential of LED lighting technology, this project developed intelligent LED fixtures for work purposes and for private homes. The two types of fixtures both meet the original project objective of good colour rendition with Ra indices above 90 and colour temperatures variable within the interval 3,300 to 4,400 K. Furthermore, with luminous efficacies of 60 lumen/W, both fixtures have energy efficiencies exceeding that of an average energy-friendly light source. (ln)

  17. High-Voltage LED Light Engine with Integrated Driver

    Energy Technology Data Exchange (ETDEWEB)

    Soer, Wouter [Lumileds LLC, San Jose, CA (United States)

    2016-02-29

    LED luminaires have seen dramatic changes in cost breakdown over the past few years. The LED component cost, which until recently was the dominant portion of luminaire cost, has fallen to a level of the same order as the other luminaire components, such as the driver, housing, optics etc. With the current state of the technology, further luminaire performance improvement and cost reduction is realized most effectively by optimization of the whole system, rather than a single component. This project focuses on improving the integration between LEDs and drivers. Lumileds has developed a light engine platform based on low-cost high-power LEDs and driver topologies optimized for integration with these LEDs on a single substrate. The integration of driver and LEDs enables an estimated luminaire cost reduction of about 25% for targeted applications, mostly due to significant reductions in driver and housing cost. The high-power LEDs are based on Lumileds’ patterned sapphire substrate flip-chip (PSS-FC) technology, affording reduced die fabrication and packaging cost compared to existing technology. Two general versions of PSS-FC die were developed in order to create the desired voltage and flux increments for driver integration: (i) small single-junction die (0.5 mm2), optimal for distributed lighting applications, and (ii) larger multi-junction die (2 mm2 and 4 mm2) for high-power directional applications. Two driver topologies were developed: a tapped linear driver topology and a single-stage switch-mode topology, taking advantage of the flexible voltage configurations of the new PSS-FC die and the simplification opportunities enabled by integration of LEDs and driver on the same board. A prototype light engine was developed for an outdoor “core module” application based on the multi-junction PSS-FC die and the single-stage switch-mode driver. The light engine meets the project efficacy target of 128 lm/W at a luminous flux greater than 4100 lm, a correlated

  18. High Output LED-Based Profile Lighting Fixture

    DEFF Research Database (Denmark)

    Török, Lajos; Beczkowski, Szymon; Munk-Nielsen, Stig;

    2011-01-01

    . The system consists of a power supply with power factor correction (PFC), a LED-driver and an optical system designed for an overall high efficiency. An interleaved boost converter was chosen as PFC converter. A soft switching phase-shifted full-bridge converter with current doubler provides isolation from...... the grid and delivers the required voltage to the LEDdriver which is a dual interleaved buck converter. Twelve highpower CBT-90 LEDs have been connected in a 4xRGBconfiguration to deliver high output of saturated colors without the need for subtractive color filters. More than 6000 lm of fixture light...

  19. High-Voltage LED Light Engine with Integrated Driver

    Energy Technology Data Exchange (ETDEWEB)

    Soer, Wouter [Lumileds LLC, San Jose, CA (United States)

    2016-02-29

    LED luminaires have seen dramatic changes in cost breakdown over the past few years. The LED component cost, which until recently was the dominant portion of luminaire cost, has fallen to a level of the same order as the other luminaire components, such as the driver, housing, optics etc. With the current state of the technology, further luminaire performance improvement and cost reduction is realized most effectively by optimization of the whole system, rather than a single component. This project focuses on improving the integration between LEDs and drivers. Lumileds has developed a light engine platform based on low-cost high-power LEDs and driver topologies optimized for integration with these LEDs on a single substrate. The integration of driver and LEDs enables an estimated luminaire cost reduction of about 25% for targeted applications, mostly due to significant reductions in driver and housing cost. The high-power LEDs are based on Lumileds’ patterned sapphire substrate flip-chip (PSS-FC) technology, affording reduced die fabrication and packaging cost compared to existing technology. Two general versions of PSS-FC die were developed in order to create the desired voltage and flux increments for driver integration: (i) small single-junction die (0.5 mm2), optimal for distributed lighting applications, and (ii) larger multi-junction die (2 mm2 and 4 mm2) for high-power directional applications. Two driver topologies were developed: a tapped linear driver topology and a single-stage switch-mode topology, taking advantage of the flexible voltage configurations of the new PSS-FC die and the simplification opportunities enabled by integration of LEDs and driver on the same board. A prototype light engine was developed for an outdoor “core module” application based on the multi-junction PSS-FC die and the single-stage switch-mode driver. The light engine meets the project efficacy target of 128 lm/W at a luminous flux

  20. New insights into consumer-led food product development

    DEFF Research Database (Denmark)

    Costa, Ana I. A.; Jongen, W.M.F.

    2006-01-01

    industry are described. Contrary to previous optimistic views, it is put forward that without significant changes taking place in the mindset of the organizations involved in Europe's food R&D, the way forward for consumer-led innovation strategies in the agri-business sector will be long and hard.......This paper builds upon a review of relevant marketing, consumer science and innovation management literature to introduce the concept of consumer-led new product development and describe its main implementation stages. The potential shortcomings of this concept's application in European food...

  1. LEDs are the panacea – and other fairy tales

    Directory of Open Access Journals (Sweden)

    James Duff

    2013-10-01

    Full Text Available Recently, there has been an explosive growth in the popularity of LED luminaries. Like all markets experiencing such expansion, it has attracted many new manufacturers.Some of these have a reputation to uphold, but many do not.As such, it can be difficult for designers to differentiate good quality products from bad quality products. This paper explores a set of standardised test methods and performance criteria associated with LED luminaries. Moreover, it proposes a set of questions for discussion within the lighting community. These questions would be used to interrogate manufacturer data and aid with the determination of product quality.

  2. The Design of the LED Display based on Solar Energy

    Directory of Open Access Journals (Sweden)

    Li Pei

    2015-01-01

    Full Text Available The development of solar energy and the LED display, the superiority of the combination of them and software design of the system are discussed in this paper. Hardware design and software design are the key elements of this paper. Solar control circuit, LED display control circuit, etc are described, charge and discharge of the battery and output of the battery is controlled by STC89C52 SCM. The design of software provides driver to the related hardware circuit. The result of the experiment have achieved anticipated effects and met the design requirements.

  3. Controlling excitons. Concepts for phosphorescent organic LEDs at high brightness

    Energy Technology Data Exchange (ETDEWEB)

    Reineke, Sebastian

    2009-11-15

    This work focusses on the high brightness performance of phosphorescent organic light-emitting diodes (OLEDs). The use of phosphorescent emitter molecules in OLEDs is essential to realize internal electron-photon conversion efficiencies of 100 %. However, due to their molecular nature, the excited triplet states have orders of magnitude longer time constants compared to their fluorescent counterparts which, in turn, strongly increases the probability of bimolecular annihilation. As a consequence, the efficiencies of phosphorescent OLEDs decline at high brightness - an effect known as efficiency roll-off, for which it has been shown to be dominated by triplet-triplet annihilation (TTA). In this work, TTA of the archetype phosphorescent emitter Ir(ppy){sub 3} is investigated in time-resolved photoluminescence experiments. For the widely used mixed system CBP:Ir(ppy){sub 3}, host-guest TTA - an additional unwanted TTA channel - is experimentally observed at high excitation levels. By using matrix materials with higher triplet energies, this effect is efficiently suppressed, however further studies show that the efficiency roll-off of Ir(ppy)3 is much more pronounced than predicted by a model based on Foerster-type energy transfer, which marks the intrinsic limit for TTA. These results suggest that the emitter molecules show a strong tendency to form aggregates in the mixed film as the origin for enhanced TTA. Transmission electron microscopy images of Ir(ppy){sub 3} doped mixed films give direct proof of emitter aggregates. Based on these results, two concepts are developed that improve the high brightness performance of OLEDs. In a first approach, thin intrinsic matrix interlayers are incorporated in the emission layer leading to a one-dimensional exciton confinement that suppresses exciton migration and, consequently, TTA. The second concept reduces the efficiency roll-off by using an emitter molecule with slightly different chemical structure, i.e. Ir(ppy){sub 2

  4. [Progress in the research on silicon-nitrogen based phosphor for white LED].

    Science.gov (United States)

    Xu, Guo-Tang; Liang, Pei; Wang, Le; Dong, Qian-Min; Liu, Yang; Li, Xiao-Yan

    2013-11-01

    With the rapid development of white LED technology, the traditional YAG : Ce3+ phosphor is difficult to meet the requirement due to the low color rendering and high color temperature. Using ultraviolet chip to stimulate the tri-phosphor has become an effective way for white LED, and it is urgent to develop novel tri-phosphor with high-performance, especially for red light-emitting materials. Silicon-nitrogen based compounds contain the network structure composed of SiN4 tetrahedron, with higher chemical and thermal stability. Because of their diversity structures, these phosphors have a higher absorption efficiency in UV-blue region, and also, with the change of substrate and active ion, emission spectrum will cover the entire visible region, resulting in a higher light conversion efficiency and light color stability, coupled with the advantages of being not sensitive to the changes in temperature and drive current, etc. These studies will have a far-reaching impact on the development of white LED. In the present paper, we introduce the preparation and latest progress of silicon-nitrogen based phosphor, including the crystal structure, spectroscopic properties and application characteristics.

  5. Double Blind: Supervising Women as Creative Practice-Led Researchers

    Science.gov (United States)

    Pedersen, Courtney; Haynes, Rachael

    2015-01-01

    Many women creative practice-led researchers appear inhibited by a number of factors directly connected to their gender. This article discusses these factors, including the culture of visual arts professional practice, the circumstances surrounding women postgraduate students and unproductive self-theories about intelligence and creativity. A…

  6. Nurse-led rehabilitation after gynaecological cancer surgery

    DEFF Research Database (Denmark)

    Seibæk, Lene

    2009-01-01

      Abstract This article presents the preliminary results and experiences from an ongoing study aiming to: Develop and test a nurse-led multidisciplinary rehabilitation programme for women who undergo surgery for localised gynaecological cancers.Evaluate the effect of the programme prospectively o...

  7. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng

    2013-01-01

    Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

  8. Nanostructured Antireflection Layer, and Application of Same to LEDs

    DEFF Research Database (Denmark)

    2013-01-01

    material, etching the substrate in a mostly anisotropic etch and concurrently etching at least a part of the thin film masking material to form a non-periodical nano structure, the nano structure comprising a plurality of cone shaped surface structures. The optical device may comprise a white LED...... or a wavelength converter for a white light source....

  9. The LED outdoor lighting revolution : Opportunities, threats and mitigation

    Science.gov (United States)

    Aube, Martin

    2017-01-01

    The presence of artificial light at night (ALAN) in environment is now known to have non negligible consequences on the night sky, the fauna, the flora and the human health. A real revolution is undergoing in the outdoor lighting industry threatens the night integrity. This revolution is driven by the advent of the cost-effective Light-Emitting Diode (LED) technology into the outdoor lighting industry. The LEDs provides many opportunities: they are long lasting, easily controlled, and generally allow a more efficient photometric design which, in term, may result in energy savings.After explaining the complex and non-linear behaviour of the propagation of the ALAN into the nocturnal environment, we will outline the potential impact of the ALAN on the human health and on the night sky, and we will introduce some dedicated indicators for its evaluation. We will focus on the role of the blue content of the ALAN in the evaluation of its impact. More specifically we will show how white LED technology, that often shows increased blue light content, compares to the traditional High Pressure Sodium technology. Finally, we will identify the possible mitigations to restrict the adverse impacts of the white LEDs in the urban and rural environment.

  10. Multiple Primary LED Lamp Colour Controller with Inherent Brightness Limitation

    NARCIS (Netherlands)

    Barcena, R.; Ackermann, B.

    2007-01-01

    There is a strong interest in using LEDs for general illumination due to the potential they offer for energy saving, environmental friendliness, new opportunities in lighting design, and control of the intensity, colour, and spatial distribution of light. General illumination requires primarily whit

  11. Stuurlicht bij anjer - Consultancy: Vergelijking van LED lampen en gloeilampen

    NARCIS (Netherlands)

    Helm, van der F.P.M.

    2013-01-01

    Als gevolg van nieuwe wetgeving zullen gloeilampen vervangen moeten worden. De kwekers moeten nu kiezen tussen de alternatieven; LED lampen of spaarlampen. In een onderzoek in de praktijk in 2012 zijn op twee bedrijven proeven aangelegd. Op 1 bedrijf bij 2 rassen en op een ander bedrijf met 2 intens

  12. The effect of LED illumination on endodontic biofilms

    DEFF Research Database (Denmark)

    Markvart, Merete

    Within endodontics photodynamic therapy (PDT) has been suggested as a disinfectant procedure during root canal treatment. A photoactive dye (photosensitizer), methylene blue or toluidine blue, are activated by a light source, usually lasers or light emitting diodes (LEDs), thereby forming free ox...

  13. A color management system for multi-colored LED lighting

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Jepsen, Jørgen;

    2015-01-01

    A new color control system is described and implemented for a five–color LED light engine, covering a wide white gamut. The system combines a new way of using pre-calibrated look-up tables and a rule-based optimization of chromaticity distance from the Planckian locus with a calibrated color sens...

  14. Small Area Array-Based LED Luminaire Design

    Energy Technology Data Exchange (ETDEWEB)

    Thomas Yuan

    2008-01-09

    This report contains a summary of technical achievements during a three-year project to demonstrate high efficiency LED luminaire designs based on small area array-based gallium nitride diodes. Novel GaN-based LED array designs are described, specifically addressing the thermal, optical, electrical and mechanical requirements for the incorporation of such arrays into viable solid-state LED luminaires. This work resulted in the demonstration of an integrated luminaire prototype of 1000 lumens cool white light output with reflector shaped beams and efficacy of 89.4 lm/W at CCT of 6000oK and CRI of 73; and performance of 903 lumens warm white light output with reflector shaped beams and efficacy of 63.0 lm/W at CCT of 2800oK and CRI of 82. In addition, up to 1275 lumens cool white light output at 114.2 lm/W and 1156 lumens warm white light output at 76.5 lm/W were achieved if the reflector was not used. The success to integrate small area array-based LED designs and address thermal, optical, electrical and mechanical requirements was clearly achieved in these luminaire prototypes with outstanding performance and high efficiency.

  15. CALiPER Application Summary Report 15. LED Floodlights

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-05-01

    This report analyzes the independently tested performance of 10 LED floodlights purchased between August and December 2011. The group included a wide range of products, both physically and in performance characteristics, which mirrors the nearly indefinite range of conventional luminaires designated as floodlights.

  16. Biologically inspired LED lens from cuticular nanostructures of firefly lantern.

    Science.gov (United States)

    Kim, Jae-Jun; Lee, Youngseop; Kim, Ha Gon; Choi, Ki-Ju; Kweon, Hee-Seok; Park, Seongchong; Jeong, Ki-Hun

    2012-11-13

    Cuticular nanostructures found in insects effectively manage light for light polarization, structural color, or optical index matching within an ultrathin natural scale. These nanostructures are mainly dedicated to manage incoming light and recently inspired many imaging and display applications. A bioluminescent organ, such as a firefly lantern, helps to out-couple light from the body in a highly efficient fashion for delivering strong optical signals in sexual communication. However, the cuticular nanostructures, except the light-producing reactions, have not been well investigated for physical principles and engineering biomimetics. Here we report a unique observation of high-transmission nanostructures on a firefly lantern and its biological inspiration for highly efficient LED illumination. Both numerical and experimental results clearly reveal high transmission through the nanostructures inspired from the lantern cuticle. The nanostructures on an LED lens surface were fabricated by using a large-area nanotemplating and reconfigurable nanomolding with heat-induced shear thinning. The biologically inspired LED lens, distinct from a smooth surface lens, substantially increases light transmission over visible ranges, comparable to conventional antireflection coating. This biological inspiration can offer new opportunities for increasing the light extraction efficiency of high-power LED packages.

  17. Effect of Laser and LED on Enzymatic Production of Ceramide

    DEFF Research Database (Denmark)

    Hongyu, Zhang; Zhang, Long; Tidemand-Lichtenberg, Peter;

    2011-01-01

    An enzyme (Phospholipase C Type I from Clostridium perfringens) was exposed to 0-810J/cm2 of energy using laser light at wavelengths 808 nm, 532nm, 1064 nm, and 1342 nm and two LED light sources at wavelengths 810 nm and 640 nm. Enzyme responses were evaluated by measuring ceramide concentration ...

  18. LED controlled flow photolysis for concentration gradients in microfluidic systems.

    Science.gov (United States)

    Potter, Oscar G; Thomas, Mark E; Breadmore, Michael C; Hilder, Emily F

    2010-05-21

    Many of the channels and reservoirs in microfluidic systems are used simply to allow liquids with different compositions to be delivered to where they are needed. An alternative approach is to use dissolved photochemicals and variable intensity LEDs to generate composition changes in situ. We applied this approach to generate concentration gradients of HCl for gradient ion chromatography.

  19. LED light requirements ... for greenhouses and growth rooms

    NARCIS (Netherlands)

    Nederhoff, E.M.

    2011-01-01

    LEDs have potential for use as grow lights in greenhouses to supplement low natural light levels, and also for use in growth rooms and 'plant factories' as the main light source. The light spectrum is critical. Unfortunately, it seems that there is not a simple recipe freely available for growing 'a

  20. Nanoscale carrier injectors for high luminescence Si-based LEDs

    NARCIS (Netherlands)

    Piccolo, G.; Kovalgin, A.Y.; Schmitz, J.

    2012-01-01

    In this paper we present the increased light emission for Sip–i–n light emitting diodes (LEDs) by geometrical scaling of the injector size for p- and n- type carriers. Simulations and electrical and optical characteristics of our realized devices support our findings. Reducing the injector size decr

  1. Student-Led IEP Meetings: Planning and Implementation Strategies

    Science.gov (United States)

    Hawbaker, Becky Wilson

    2007-01-01

    Although self-determination in general and student-led IEPs in particular have received attention nationally, the extent to which students are leading their IEP meetings remains uncertain, and the rhetoric does not seem to match the reality for the majority of students with disabilities and their IEP meetings. Self determined educators are needed…

  2. EC-LEDS Mexico: Advancing Clean Energy Goals

    Energy Technology Data Exchange (ETDEWEB)

    2016-07-01

    EC-LEDS works with the government of Mexico to help meet its goals of reducing greenhouse gas emissions from the energy sector. The program targets specific, highly technical areas where Mexico has indicated the program can add value and make an impact.

  3. Nobel Prize in Physics: The birth of the blue LED

    Science.gov (United States)

    Nanishi, Yasushi

    2014-12-01

    The development of practical blue LEDs required great perseverance by several Japanese scientists who had to learn how to fabricate high-quality films of GaN and effectively dope them to create light-emitting p-n junctions.

  4. Values-led Participatory Design - Mediating the Emergence of Values

    DEFF Research Database (Denmark)

    Iversen, Ole Sejer; Leong, Tuck Wah

    2012-01-01

    with severe intellectual disabilities, in an art museum. By describing how we establish, negotiate and the debrief values during this initial phase of a values-led inquiry. By foregrounding both explicit and implicit mediation in the PD process we show how a theoretical understanding of mediation can...

  5. Reflector Design Method for Rotational Uniform Illuminance System with LED

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qi-hui; WANG Hong; JI Ling-ling

    2009-01-01

    Based on nonimaging design method,uniform illuminance systems with LED source were developed to create a uniform illuminated circular region with a desired size in a screen at a prescribed place.By using ray-tracing software based on Monte-Carlo method,the simulation results show that in the illuminated region the luminous uniformity is higher than 90%.

  6. Optical and thermal simulation chain for LED package

    NARCIS (Netherlands)

    Tapaninen, O.; Myohanen, P.; Majanen, M.; Sitomaniemi, A.; Olkkonen, J.; Hildenbrand, V.; Gielen, A.W.J.; Mackenzie, F.V.; Barink, M.; Smilauer, V.; Patzak, B.

    2016-01-01

    This paper presents a test case for coupling two physical aspects of an LED, optical and thermal, using specific simulation models coupled through an open source platform for distributed multi-physics modelling. The glue code for coupling is written with Python programming language including routine

  7. Patient safety in midwifery-led care in the Netherlands

    NARCIS (Netherlands)

    Martijn, L.M.; Jacobs, A.J.M; Maassen, I.I.; Buitendijk, S.S.; Wensing, M.J.

    2013-01-01

    OBJECTIVE: to describe the incidence and characteristics of patient safety incidents in midwifery-led care for low-risk pregnant women. DESIGN: multi-method study. SETTING: 20 midwifery practices in the Netherlands; 1,000 patient records. POPULATION: low-risk pregnant women. METHODS: prospective inc

  8. Critical red Components for Next-Generation White LEDs

    NARCIS (Netherlands)

    Lin, Chun; Meijerink, A; Liu, R.-S.

    2016-01-01

    Warm white LEDs with a high color rendering index and a low correlated color temperature have undergone rapid development. In this regard, red-emitting materials-such as fluoride phosphors, namely, A2MF6:Mn(4+) (A = K, Na, and Cs; M = Si, Ge, Zr, Sn, and Ti) and XSiF6:Mn(4+) (X = Ba or Zn), nitridoa

  9. Ghana Fiasco Shows Risks of Faculty-Led Study Trips

    Science.gov (United States)

    Fischer, Karin

    2007-01-01

    This article illustrates the importance of preparation for professors who take students overseas. A University of Washington study-abroad program in Ghana that was cut short last summer after the medical evacuation of half of its participants highlights the potential hazards associated with programs led by individual faculty members who may lack…

  10. 130 LPW 1000 Lm Warm White LED for Illumination

    Energy Technology Data Exchange (ETDEWEB)

    Soer, Wouter [Philips Lumileds Lighting Company LLC, San Jose, CA (United States)

    2012-12-21

    An illumination-grade warm-white LED, having correlated color temperature (CCT) between 2700 and 3500 K and capable of producing 1000 lm output at over 130 lm/W at room temperature, has been developed in this program. The high-power warm-white LED is an ideal source for use in indoor and outdoor lighting applications. Over the two year period, we have made the following accomplishments: • Developed a low-cost high-power white LED package and commercialized a series of products with CCT ranging from 2700 to 5700 K under the product name LUXEON M; • Demonstrated a record efficacy of 124.8 lm/W at a flux of 1023 lm, CCT of 3435 K and color rendering index (CRI) over 80 at room temperature in the productized package; • Demonstrated a record efficacy of 133.1 lm/W at a flux of 1015 lm, CCT of 3475 K and CRI over 80 at room temperature in an R&D package. The new high-power LED package is a die-on-ceramic surface mountable LED package. It has four 2 mm2 InGaN pump dice, flip-chip attached to a ceramic submount in a 2x2 array configuration. The submount design utilizes a design approach that combines a high-thermal- conductivity ceramic core for die attach and a low-cost and low-thermal-conductivity ceramic frame for mechanical support and as optical lens carrier. The LED package has a thermal resistance of less than 1.25 K/W. The white LED fabrication also adopts a new batch level (instead of die-by-die) phosphor deposition process with precision layer thickness and composition control, which provides not only tight color control, but also low cost. The efficacy performance goal was achieved through the progress in following key areas: (1) high-efficiency royal blue pump LED development through active region design and epitaxial growth quality improvement (funded by internal programs); (2) improvement in extraction efficiency from the LED package through improvement of InGaN-die-level and package-level optical extraction efficiency; and (3) improvement in phosphor

  11. Selective-area nanoheteroepitaxy for light emitting diode (LED) applications

    Science.gov (United States)

    Wildeson, Isaac H.

    Over 20% of the electricity in the United States is consumed for lighting, and the majority of this energy is wasted as heat during the lighting process. A solid-state (or light emitting diode (LED)-based) light source has the potential of saving the United States billions of dollars in electricity and reducing megatons of global CO2 emissions annually. While white light LEDs are currently on the market with efficiencies that are superior to incandescent and fluorescent light sources, their high up-front cost is inhibiting mass adoption. One reason for the high cost is the inefficiency of green and amber LEDs that can used to make white light. The inefficiency of green and amber LEDs results in more of these chips being required, and thus a higher cost. Improvements in the performance of green and amber LEDs is also required in order to realize the full potential of solid-state lighting. Nanoheteroepitaxy is an interesting route towards achieving efficient green and amber LEDs as it resolves major challenges that are currently plaguing III-nitride LEDs such as high dislocation densities and limited active region critical thicknesses. A method for fabricating III-nitride nanopyramid LEDs is presented that employs conventional processing used in industry. The present document begins with an overview of the current challenges in III-nitride LEDs and the benefits of nanoheteroepitaxy. A process for controlled selective-area growth of nanopyramid LEDs by organometallic vapor phase epitaxy has been developed throughout the course of this work. Dielectric templates used for the selective-area growth are patterned by two methods, namely porous anodic alumina and electron-beam lithography. The dielectric templates serve as efficient dislocation filters; however, planar defects are initiated during lower temperature growth on the nanopyramids. The quantum wells outline six semipolar planes that form each hexagonal pyramid. Quantum wells grown on these semipolar planes

  12. Chemical use

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of research and activities related to chemical use on Neal Smith National Wildlife Refuge between 1992 and 2009. The chemicals used on the Refuge...

  13. Chemical Reactors.

    Science.gov (United States)

    Kenney, C. N.

    1980-01-01

    Describes a course, including content, reading list, and presentation on chemical reactors at Cambridge University, England. A brief comparison of chemical engineering education between the United States and England is also given. (JN)

  14. Hepatocarcinogenesis and new genes that related to hepatic lipid metabolism%脂质代谢相关新基因与肝肿瘤发生研究进展

    Institute of Scientific and Technical Information of China (English)

    谢棒祥(综述); 朴正福(审校)

    2014-01-01

    Genetic and metabolic abnormalities exist in malignant transformation. Recent studies suggest that some new genes,such as ALDOC,TUBB5,ANXA2,FABP4,ApoA1 and AOP1,CIDE’s family,ATGL and HSL,ACADL,SCD1,FASN or ACC1,and so on,are related to hepatic lipid metabolism and play some roles in the hepatocarcinogenesis. Some molecules in these genes might be the targets for tumor therapy in the future.%研究发现,恶性肿瘤存在基因异常和代谢异常,后者表现在能量代谢的异常较突出,而作为肿瘤能量来源底物的脂肪酸代谢研究并不多见。本文讨论了与脂质代谢相关的新基因,如 ALDOC、TUBB5、ANXA2、FABP4、ApoA1和 AOP1,CIDE 家族蛋白(Cidea、Cideb、Fsp27),在产生癌症相关性恶病质中起关键作用的脂肪甘油三酯脂肪酶(ATGL)和激素敏感性脂肪酶(HSL),长链酰基辅酶 A 脱氢酶(ACADL),SCD1、FASN 或 ACC1等。由于肿瘤细胞与正常细胞在能量代谢上存在明显的差异,因此根据这种区别以能量代谢途径上的某个分子作为肿瘤治疗的靶点是完全有可能的。

  15. A self-calibrating led-based solar test platform

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Sylvester-Hvid, Kristian O.; Jørgensen, Mikkel

    2011-01-01

    A compact platform for testing solar cells is presented. The light source comprises a multi-wavelength high-power LED (light emitting diode) array allowing the homogenous illumination of small laboratory solar cell devices (substrate size 50 × 25 mm) within the 390–940 nm wavelength range......, it is possible to perform all the commonly employed measurements on the solar cell at very high speed without moving the sample. In particular, the LED-based illumination system provides an alternative to light-biased incident photon-to-current efficiency measurement to be performed which we demonstrate. Both...... top and bottom contact is possible and the atmosphere can be controlled around the sample during measurements. The setup was developed for the field of polymer and organic solar cells with particular emphasis on enabling different laboratories to perform measurements in the same manner and obtain...

  16. CREATIVITY AND IMPACT OF ADVERTISING ELECTRONIC LED BILLBOARDS IN JAKARTA

    Directory of Open Access Journals (Sweden)

    Suprayitno

    2016-09-01

    Full Text Available The creativity and the impact of advertising electronic LED billboards in Jakarta was an approach to see, to know and to understand in a deeper way. Creativity decisions affect all advertising, art, and knowledge combined with the phrase creative strategy. Creative advertising ideas must be original, unique, different, new, unexpected and right on target. The approach used was qualitative research methods, including data collection in the form of literature review, interviews with the actors and the surrounding communities, as well as documenting the billboard directly outside the media was located. The results of this research are the analysis report the creativity and impact of LED electronic billboard advertising effectiveness, is expected to produce a more detailed picture. So that students and practitioners can use the visual communication design, process, and maximize the advertising rules in designing a design to reach the stage of design creativity and better application.

  17. Radiation Hardening of LED Luminaires for Accelerator Tunnels

    CERN Document Server

    Devine, James D

    2016-01-01

    This paper summarises progress made towards the radiation hardening of LED emergency luminaires for evacuation and emergency response within the underground areas of the CERN accelerator complex. The objective has been to radiation harden existing Commercial Off-The-Shelf (COTS) emergency luminaires to maximise lighting performance, without compromising IEC 60598-2-22 compliance. A systems level approach has been adopted, leading to the development of a diode bridge based AC/DC power converter. Modified COTS luminaires including this converter design have been irradiated (to 100 kGy TID using a Cobalt-60 source), with results of a subsequent photometric analysis presented. Following encouraging tests results, a reference design for the power converter has been released under the CERN Open Hardware License to encourage manufacturer adoption. The paper concludes with areas of interest for future research in further improving the radiation hardness of LED emergency lighting for accelerators with detailed studies...

  18. A fast template matching method for LED chip Localization

    Directory of Open Access Journals (Sweden)

    Zhong Fuqiang

    2015-01-01

    Full Text Available Efficiency determines the profits of the semiconductor producers. So the producers spare no effort to enhance the efficiency of every procedure. The purpose of the paper is to present a method to shorten the time to locate the LED chips on wafer. The method consists of 3 steps. Firstly, image segmentation and blob analyzation are used to predict the positions of potential chips. Then predict the orientations of potential chips based on their dominant orientations. Finally, according to the positions and orientations predicted above, locate the chips precisely based on gradient orientation features. Experiments show that the algorithm is faster than the traditional method we choose to locate the LED chips. Besides, even the orientations of the chips on wafer are of big deviation to the orientation of the template, the efficiency of this method won't be affected.

  19. Charge Management for Gravitational Wave Observatories using UV LEDs

    CERN Document Server

    Pollack, S E; Schlamminger, S; Hagedorn, C A; Gundlach, J H

    2009-01-01

    Accumulation of electrical charge on the end mirrors of gravitational wave observatories, such as the space-based LISA mission and ground-based LIGO detectors, can become a source of noise limiting the sensitivity of such detectors through electronic couplings to nearby surfaces. Torsion balances provide an ideal means for testing gravitational wave technologies due to their high sensitivity to small forces. Our torsion pendulum apparatus consists of a movable Au-coated Cu plate brought near a Au-coated Si plate pendulum suspended from a non-conducting quartz fiber. A UV LED located near the pendulum photoejects electrons from the surface, and a UV LED driven electron gun directs photoelectrons towards the pendulum surface. We have demonstrated both charging and discharging of the pendulum with equivalent charging rates of $\\sim

  20. Design of White LED Energy-saving Street Lamp

    Institute of Scientific and Technical Information of China (English)

    CHEN Huan-jie; FENG Jin-yuan

    2008-01-01

    An energy-saving light-emitting-diode(LED) street lamp was conducted. Based on the simulation by optical software TracePro, a physical street lamp system including 600 white LEDs was achieved. This system was operated under a constant current of 20mA for each unit, and the electric power consumption of the whole lamp was only 42W. Experimental results demonstrated that the total average illuminance reached 8.8lx and the overall uniformity was 0.370 for a 30-m-long and 10-m-wide test area at a height of 8m, which is fully acceptable for the current standard for sub-main road.

  1. Demonstration Assessment of LED Roadway Lighting: Philadelphia, PA

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Tuenge, Jason R.; Poplawski, Michael E.

    2012-09-01

    For this demonstration assessment, 10 different groups of LED luminaires were installed at three sites in Philadelphia, PA. Each of the three sites represented a different set of conditions, most importantly with regard to the incumbent HPS luminaires, which were nominally 100 W, 150 W, and 250 W. The performance of each product was evaluated based on manufacturer data, illuminance calculations, field measurements of illuminance, and the subjective impressions of both regular and expert observers.

  2. Digital controlling system to the set of high power LEDs

    Science.gov (United States)

    Gilewski, Marian; Gryko, Lukasz; Zajac, Andrzej

    2013-07-01

    In the paper is described the concept and architecture of the multi-channel control system for set of high-power LEDs. The broadband source of radiation for prototype illuminator is dedicated to the investigation of Low Level Laser Therapy procedures. The general scheme of the system, detailed schemes, control algorithm and its implementation description in FPGA structure is presented. The temperature conditions and the opportunity to work with a microcomputer are characterized.

  3. Implementing a patient-led service for chronic conditions.

    Science.gov (United States)

    Pope, Denise; Tipler, Sue; Kirwan, John; Hewlett, Sarah

    Many chronic conditions with fluctuating levels of disease activity are traditionally managed by lifelong regular medical reviews. However, this means appointments do not always coincide with patient need, while the volume of reviews makes it difficult to respond quickly to requests for help. Research in rheumatoid arthritis suggests that hospital-initiated reviews can be replaced by patient-initiated reviews, supported by nurse-led initiatives.

  4. High Efficacy Green LEDs by Polarization Controlled MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, Christian [Rensselaer Polytechnic Inst., Troy, NY (United States)

    2013-03-31

    Amazing performance in GaInN/GaN based LEDs has become possible by advanced epitaxial growth on a wide variety of substrates over the last decade. An immediate push towards product development and worldwide competition for market share have effectively reduced production cost and generated substantial primary energy savings on a worldwide scale. At all times of the development, this economic pressure forced very fundamental decisions that would shape huge industrial investment. One of those major aspects is the choice of epitaxial growth substrate. The natural questions are to what extend a decision for a certain substrate will limit the ultimate performance and to what extent, the choice of a currently more expensive substrate such as native GaN could overcome any of the remaining performance limitations. Therefore, this project has set out to explore what performance characteristic could be achieved under the utilization of bulk GaN substrate. Our work was guided by the hypotheses that line defects such as threading dislocations in the active region should be avoided and the huge piezoelectric polarization needs to be attenuated – if not turned off – for higher performing LEDs, particularly in the longer wavelength green and deep green portions of the visible spectrum. At their relatively lower performance level, deep green LEDs are a stronger indicator of relative performance improvements and seem particular sensitive to the challenges at hand.

  5. 8. Are nurse-led prosthetic valve anticoagulation clinics effective?

    Directory of Open Access Journals (Sweden)

    F. Obeid

    2016-07-01

    Full Text Available Valvular heart disease is a major and serious healthcare issue. There is an increasing evidence that Nurse-led anticoagulation clinics may improve patients’ management and care.This is a retrospective comparison study that included the first 94 patients enrolled in the Nurse Led Prosthetic Valve Anticoagulation Clinic (PVATC in King Abdul-Aziz Cardiac Centre between April and June 2013, and received Warfarin by General Cardiology Clinics for one year pre enrollment in PVATC, and one year after. Time in Therapeutic Range (TTR of the International Normalized Ratio (INR was calculated and compared between pre and post PVATC enrolment. Other data including demographics and comorbidities were collected and analyzed. Mean age of patients was 53 ± 12.5 years and males were 56%. Atrial fibrillation was found in 37%, Diabetes Mellitus in 28% and Hypertension in 34%. Mean TTR was 72% pre enrollment in PVATC as compared to 78.9% after (P < 0.006. Median TTR was 75% pre, and 81.5% after attending the PVATC (P < 0.0001. 56% of patients pre enrollment had TTR values above 70% threshold, compared to 75% after enrollment. Nurse-Led PVATC has significant impact on the care provided to patients receiving anticoagulation treatment.

  6. The Rewards and Challenges of Export-Led Strategies

    Directory of Open Access Journals (Sweden)

    Hany H. MAKHLOUF

    2016-09-01

    Full Text Available Abstract. The economic achievements of post- WWII Japan and Germany, the success of the Asian Four Tigers in the 1970s and 1980s, and the impressive growth of China, after adopting an export-led strategy in 1978, have caused many nations to view the export-ledmodel as the fastestroute to economic growth and financial stability. As a result, many governments started to promote and protect their countries’ exports,and mix politics, diplomacy and trade as well as seek greater access to friendly countries’ markets. Export-led development strategies, however, carry some risks, such as increased dependence on foreign markets and political forces that are beyond the exporters’ control. Global market forces, at times, cause export-dependent countries to have a sudden decline in their export revenues as the oil exporting countries have been experiencing as a result of a sharp decline in the world price of crude oil since 2014. This paper examines the main benefits, costs, and risks associated with export-led strategies, particularly as adopted by developing countries. It further explores the motives and risks faced by individual companies as they sell some of their products outside their home markets.Keywords. Import substitution, Trade liberalization, Infant industries, Export promotion, Foreign investment, Export infrastructure.JEL. F10, F16, F17, F41.

  7. Demonstration of LED Street Lighting in Kansas City, MO

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, Bruce R.; Royer, Michael P.; Hadjian, M.; Kauffman, Rick

    2013-06-10

    Nine different streetlighting products were installed on various streets in Kansas City, Missouri during February, 2011, to evaluate their performance relative to the incumbent high-pressure sodium (HPS) lighting. The applications investigated included 100 W, 150 W, 250 W, and 400 W HPS installations. Initial measurements and comparisons included power, illuminance, and luminance; sample illuminance readings have continued at each of the nine locations at roughly 1,000-hour operating intervals since then. All of the LED products consumed less power than their HPS counterparts—with a mean difference of 39% and a range of 31% to 51%—but they also emitted 31% fewer lumens, on average. The net result is just a 15% increase in mean efficacy. Applying the city’s stringent light loss factors to the initial measured data meant that five of the LED products (and two of the HPS luminaires) were predicted to eventually fail to meet the specified mean illuminance over their lifetimes; however, the specified light loss levels are not expected to be reached by the LED products until some distant future date (between 12 and 30 years after installation according to manufacturer specification sheet estimates). The practical value of designing streetlighting systems to meet illumination requirements more than 15 years in the future is questioned. Numerous sources of variation in field measurements are noted throughout the report, particularly seasonal influences such as ambient temperature and foliage that are evident in the time-series illuminance data.

  8. Integrating sphere design for characterization of LED efficacy

    Science.gov (United States)

    Mujahid, Muhammad Abdul Aziz Al; Panatarani, C.; Maulana, Dwindra W.; Wibawa, Bambang Mukti; Joni, I. Made

    2016-02-01

    The integrating sphere (IS) is one of the most important device in characterization of illuminance of a light source, such as CFL, LED etc. to obtain their efficacy. IS is a hollowed sphere with its interior covered with a diffuse white reflective coating where its accuracy of the measurement is highly affected by reflectance of its interior coating. This paper report the preparation of inner surface coating of the IS with inner diameter of 25 cm attempt to create a durable and highly reflective interior coating by combining BaSO4 with a binding material (either Polyethylene Glycol (PEG) or white paint). The various inner surface coating mixture vary in weight % ratio of BaSO4:PEG or BaSO4:white paint were investigated. The results show that the inner surface coating mixture of BaSO4:PEG (99.8:0.2) has highest reflectance compared to others mixture. The IS with best mixture was calibrated with white LED and resulted an average sphere multiplier (M) was 8.7, and average reflectance (ρ) was 0.90. The result of the relative error of luminescence measurement using calibrated M and ρ is 6.7 %. It is concluded that the developed IS produced lower allowed error compared to the commercially available IS. However at lower wavelength shows lower intensity compare to the available datasheet of the LED under investigation.

  9. LED-Based High-Voltage Lines Warning System

    Directory of Open Access Journals (Sweden)

    Eldar MUSA

    2013-04-01

    Full Text Available LED-based system, running with the current of high-voltage lines and converting the current flowing through the line into the light by using a toroid transformer, has been developed. The transformer’s primary winding is constituted by the high voltage power line. Toroidal core consists of two equal parts and the secondary windings are evenly placed on these two parts. The system is mounted on the high-voltage lines as a clamp. The secondary winding ends are connected in series by the connector on the clamp. LEDs are supplied by the voltage at the ends of secondary. Current flowing through highvoltage transmission lines is converted to voltage by the toroidal transformer and the light emitting LEDs are supplied with this voltage. The theory of the conversion of the current flowing through the line into the light is given. The system, running with the current of the line and converting the current into the light, has been developed. System has many application areas such as warning high voltage lines (warning winches to not hinder the high-voltage lines when working under the lines, warning planes to not touch the high-voltage lines, remote measurement of high-voltage line currents, and local illumination of the line area

  10. Evaluation of a nurse-led haemophilia counselling service.

    LENUS (Irish Health Repository)

    O'Shea, Eadaoln

    2012-01-01

    Genetic counselling and testing for females with a family history of haemophilia has long been advocated. However, there is little research in regard to clients\\' satisfaction with the existing counselling models in haemophilia, and in particular with nurse-led clinics. The purpose of this study was to evaluate whether clients were satisfied with a nurse-led carrier testing clinic and counselling service. A retrospective quantitative study of clients\\' satisfaction and perceived knowledge was undertaken using an anonymous questionnaire. A sample of 42 women who had attended the clinic in the last 12 months was identified. The response rate for the study was 71% (n = 30).Two thirds of the respondents were 35 years of age or younger, 93% had a family history of haemophilia and 56% were diagnosed as carriers. Perceived understanding and knowledge increased significantly between the first and second appointments (p < 0.001). Overall, the study identified a high level of client satisfaction with the nurse-led carrier testing clinic and counselling service.

  11. A novel LED-based device for occlusal caries detection.

    Science.gov (United States)

    Aktan, Ali Murat; Cebe, Mehmet Ata; Ciftçi, Mehmet Ertuğrul; Sirin Karaarslan, Emine

    2012-11-01

    The aim of this in-vitro study was to compare the performance of laser-based (DIAGNOdent, KaVo, Biberach, Germany) and LED-based (Midwest Caries I.D., DENTSPLY Professional, New York, USA) caries detectors in the detection of occlusal caries in permanent molars. The study consisted of 129 visually sound or non-cavitated pits or fissures in 82 extracted permanent human molar teeth. Two trained examiners used the laser-based and LED-based caries detectors to examine the fissures for caries. The teeth were then sectioned at the surfaces suspected of containing occlusal caries and histologically evaluated using stereomicroscopy as a gold standard. Inter-examiner reliability of the caries detector examination was assessed using Cohen's Kappa statistics. The sensitivity, specificity, and accuracy in diagnosing occlusal caries using the two devices were calculated according to appropriate cut-off scores. Receiver operating characteristic (ROC) curves were also determined to compare the diagnostic performance of the devices in occlusal caries diagnosis. The cut-off level of significance was taken as p = 0.005. Cohen's Kappa showed substantial agreement for the laser-based caries detector (0.74), and almost perfect agreement for the LED-based (0.89) caries detector. The specificity of the laser-based device varied from 0.49 to 0.97 at T1 and T2. Its sensitivity varied from 0.33 to 0.65 at T1 and T2. The specificity of the LED-based device varied from 0.48 to 0.56 at T1 and T2. Its sensitivity varied from 0.65 to 0.84 at T1 and from 0.80 to 0.84 at T2. Taking the limitations of the current study into consideration, the DIAGNOdent laser pen was more accurate in determining when teeth were free of occlusal caries than was the Midwest Caries I.D. LED-based device, although the Midwest Caries I.D. device more often revealed the presence of occlusal caries than did the DIAGNOdent pen.

  12. Application Summary Report 22: LED MR16 Lamps

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.

    2014-07-23

    This report analyzes the independently tested photometric performance of 27 LED MR16 lamps. It describes initial performance based on light output, efficacy, distribution, color quality, electrical characteristics, and form factor, with comparisons to a selection of benchmark halogen MR16s and ENERGY STAR qualification thresholds. Three types of products were targeted. First, CALiPER sought 3000 K lamps with the highest rated lumen output (i.e., at least 500 lm) or a claim of equivalency to a 50 W halogen MR16 or higher. The test results indicate that while the initial performance of LED MR16s has improved across the board, market-available products still do not produce the lumen output and center beam intensity of typical 50 W halogen MR16 lamps. In fact, most of the 18 lamps in this category had lower lumen output and center beam intensity than a typical 35 W halogen MR16 lamp. Second, CALiPER sought lamps with a CRI of 90 or greater. Only four manufacturers were identified with a product in this category. CALiPER testing confirmed the performance of these lamps, which are a good option for applications where high color fidelity is needed. A vast majority of the LED MR16 lamps have a CRI in the low 80s; this is generally acceptable for ambient lighting, but may not always be acceptable for focal lighting. For typical LED packages, there is a fundamental tradeoff between CRI and efficacy, but the lamps in the high-CRI group in this report still offer comparable performance to the rest of the Series 22 products in other performance areas. Finally, CALiPER sought lamps with a narrow distribution, denoted as a beam angle less than 15°. Five such lamps were purchased. Notably, no lamp was identified as having high lumen output (500 lumens or greater), high CRI (90 or greater), a narrow distribution (15° or less), and an efficacy greater than 60 lm/W. This would be an important achievement for LED MR16s especially if output could reach approximately 700 800 lumens

  13. Highly-efficient, tunable green, phosphor-converted LEDs using a long-pass dichroic filter and a series of orthosilicate phosphors for tri-color white LEDs.

    Science.gov (United States)

    Oh, Ji Hye; Oh, Jeong Rok; Park, Hoo Keun; Sung, Yeon-Goog; Do, Young Rag

    2012-01-02

    This study introduces a long-pass dichroic filter (LPDF) on top of a phosphor-converted LED (pc-LED) packing associated with each corresponding tunable orthosilicate ((Ba,Sr)2SiO4:Eu) phosphor in order to fabricate tunable green pc-LEDs. These LPDF-capped green pc-LEDs provide luminous efficacies between 143–173 lm/W at 60 mA in a wavelength range between 515 and 560 nm. These tunable green pc-LEDs can replace green semiconductor-type III-V LEDs, which present challenges with respect to generating high luminous efficacy. We also introduce the highly-efficient tunable green pc-LEDs into tri-color white LED systems that combine an InGaN blue LED and green/red full down-converted pc-LEDs. The effect of peak wavelength in the tunable green pc-LEDs on the optical properties of a tri-color package white LED is analyzed to determine the proper wavelength of green color for tri-color white LEDs. The tri-color white LED provides excellent luminous efficacy (81.5–109 lm/W) and a good color rendering index (64–87) at 6500 K of correlated color temperature (CCT) with the peak wavelength of green pc-LEDs. The luminous efficacy of the LPDF-capped green monochromatic pc-LED and tri-color package with tunable green pc-LEDs can be increased by improving the external quantum efficiency of blue LEDs and the conversion efficiency of green pc-LEDs.

  14. A comparison of pediatric basic life support self-led and instructor-led training among nurses

    DEFF Research Database (Denmark)

    Vestergaard, Lone D; Løfgren, Bo; Jessen, Casper L

    2015-01-01

    .5 in the self-training group vs. 10.0 in the instructor-led group, P=0.51) or in any of the 15 parameters. After the study, all participants felt that they had improved their skills and felt capable of performing PBLS. CONCLUSION: Self-training is not statistically different to instructor-led training......OBJECTIVE: Pediatric cardiac arrest carries a poor prognosis. Basic life support improves survival. Studies on pediatric basic life support (PBLS) training are sparse. The aim of our study was to investigate the effect of self-training in PBLS. PARTICIPANTS AND METHODS: We conducted a prospective...... in teaching PBLS. Self-evaluated confidence improved, but showed no difference between groups. PBLS may be disseminated through self-training....

  15. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products Part 2: LED Manufacturing and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Scholand, Michael; Dillon, Heather E.

    2012-05-01

    Part 2 of the project (this report) uses the conclusions from Part 1 as a point of departure to focus on two objectives: producing a more detailed and conservative assessment of the manufacturing process and providing a comparative LCA with other lighting products based on the improved manufacturing analysis and taking into consideration a wider range of environmental impacts. In this study, we first analyzed the manufacturing process for a white-light LED (based on a sapphire-substrate, blue-light, gallium-nitride LED pumping a yellow phosphor), to understand the impacts of the manufacturing process. We then conducted a comparative LCA, looking at the impacts associated with the Philips Master LEDbulb and comparing those to a CFL and an incandescent lamp. The comparison took into account the Philips Master LEDbulb as it is now in 2012 and then projected forward what it might be in 2017, accounting for some of the anticipated improvements in LED manufacturing, performance and driver electronics.

  16. Development of Advanced LED Phosphors by Spray-based Processes for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Cabot Corporation

    2007-09-30

    The overarching goal of the project was to develop luminescent materials using aerosol processes for making improved LED devices for solid state lighting. In essence this means improving white light emitting phosphor based LEDs by improvement of the phosphor and phosphor layer. The structure of these types of light sources, displayed in Figure 1, comprises of a blue or UV LED under a phosphor layer that converts the blue or UV light to a broad visible (white) light. Traditionally, this is done with a blue emitting diode combined with a blue absorbing, broadly yellow emitting phosphor such as Y{sub 3}Al{sub 5}O{sub 12}:Ce (YAG). A similar result may be achieved by combining a UV emitting diode and at least three different UV absorbing phosphors: red, green, and blue emitting. These emitted colors mix to make white light. The efficiency of these LEDs is based on the combined efficiency of the LED, phosphor, and the interaction between the two. The Cabot SSL project attempted to improve the over all efficiency of the LED light source be improving the efficiency of the phosphor and the interaction between the LED light and the phosphor. Cabot's spray based process for producing phosphor powders is able to improve the brightness of the powder itself by increasing the activator (the species that emits the light) concentration without adverse quenching effects compared to conventional synthesis. This will allow less phosphor powder to be used, and will decrease the cost of the light source; thus lowering the barrier of entry to the lighting market. Cabot's process also allows for chemical flexibility of the phosphor particles, which may result in tunable emission spectra and so light sources with improved color rendering. Another benefit of Cabot's process is the resulting spherical morphology of the particles. Less light scattering results when spherical particles are used in the phosphor layer (Figure 1) compared to when conventional, irregular shaped

  17. Growth and Quality of Chinese Kale Grown Under Different LEDs

    Institute of Scientific and Technical Information of China (English)

    Jintong XlN; Houcheng LlU; Shiwei SONG; Riyuan CHEN; Guangwen SUN

    2015-01-01

    Objective] This study was conducted to investigate the effects of light quality on growth and quality of Chinese kale (Brassica alboglabra Bailey). [Method] Chinese kale was grown in hydroponic under three different Light Emitting Diode (LEDs) conditions [red:blue=8:1 (8R1B), red:blue=6:3 (6R3B) and red:green:blue=6:2:1 (6R2G1B), 12 h light, 50 μmol/(m2·s)]. Then its growth and quality indices including root and shoot fresh weight and dry weight, concentrations of soluble protein, vita-min C, nitrate, soluble phenols, flavonoids, soluble sugar, free amino acids, and ac-tivity of nitrate reductase were measured. [Result] There was no significant differ-ence in plant height, diameter of flower stalk and leaf number among three LED treatments. The fresh weight of shoot, root and plant in 8R1B and 6R2G1B was significantly higher than in 6R3B. The dry weight of shoot and plant in 8R1B was significantly higher than in 6R3B. The concentrations of vitamin C, soluble protein and soluble sugar in flower stalk of 6R3B treatment were significantly higher than those in 8R1B and 6R2G1B, while there was no remarkable difference in concen-trations of reducing sugar, soluble phenol, flavonoids and free amino acid among the three treatments. The nitrate concentration in flower stalk of 6R3B was signifi-cantly lower than in the other two treatments, and the activity of nitrate reductase in 6R3B was significantly higher than in the other two treatments. [Conclusion] The LED treatment of red:blue=6:3 was more suitable for the growth of Chinese kale.

  18. 77 FR 58406 - Certain LED Photographic Lighting Devices and Components Thereof; Notice of Request for...

    Science.gov (United States)

    2012-09-20

    ... COMMISSION Certain LED Photographic Lighting Devices and Components Thereof; Notice of Request for Statements... general exclusion order against certain LED photographic lighting devices and components thereof. The ALJ alternatively recommended a limited exclusion order against certain LED photographic lighting devices...

  19. Simple LED spectrophotometer for analysis of color information.

    Science.gov (United States)

    Kim, Ji-Sun; Kim, A-Hee; Oh, Han-Byeol; Goh, Bong-Jun; Lee, Eun-Suk; Kim, Jun-Sik; Jung, Gu-In; Baek, Jin-Young; Jun, Jae-Hoon

    2015-01-01

    A spectrophotometer is the basic measuring equipment essential to most research activity fields requiring samples to be measured, such as physics, biotechnology and food engineering. This paper proposes a system that is able to detect sample concentration and color information by using LED and color sensor. Purity and wavelength information can be detected by CIE diagram, and the concentration can be estimated with purity information. This method is more economical and efficient than existing spectrophotometry, and can also be used by ordinary persons. This contribution is applicable to a number of fields because it can be used as a colorimeter to detect the wavelength and purity of samples.

  20. Heat Transfer Characteristics in High Power LED Packaging

    Directory of Open Access Journals (Sweden)

    Chi-Hung Chung

    2014-03-01

    Full Text Available This study uses the T3Ster transient thermal resistance measuring device to investigate the effects to heat transfer performances from different LED crystal grains, packaging methods and heat-sink substrates through the experimental method. The experimental parameters are six different types of LED modules that are made alternatively with the crystal grain structure, the die attach method and the carrying substrate. The crystal grain structure includes the lateral type, flip chip type and vertical type. The die attach method includes silver paste and the eutectic structure. The carrying substrates are aluminum oxide (Alumina and aluminum nitride (AIN ceramic substrates and metal core PCB (MCPCB. The experimental results show that, under the conditions of the same crystal grain and die attach method, the thermal resistance values for the AIN substrate and the Alumina substrate are 2.1K/W and 5.1K/W, respectively and the total thermal resistance values are 7.3K/W and 10.8K/W. Compared to the Alumina substrate, the AIN substrate can effectively lower the total thermal resistance value by 32.4%. This is because the heat transfer coefficient of the AIN substrate is higher than that of the Alumina substrate, thus effectively increasing its thermal conductivity. In addition, under the conditions of the same crystal grain and the same substrate, the packaging methods are using silver paste and the eutectic structure for die attach. Their thermal resistance values are 5.7K/W and 2.7K/W, respectively, with a variance of 3K/W. Comparisons of the crystal grain structure show that the thermal resistance for the flip chip type is lower than that of the traditional lateral type by 0.9K/W. This is because the light emitting layer of the flip chip crystal grain is closer to the heat-sink substrate, shortening the heat dissipation route, and thus lowering the thermal resistance value. For the total thermal resistance, the crystal grain structure has a lesser

  1. Stakeholder perceptions of a nurse led walk-in centre

    Directory of Open Access Journals (Sweden)

    Parker Rhian M

    2012-11-01

    Full Text Available Abstract Background As many countries face primary care medical workforce shortages and find it difficult to provide timely and affordable care they seek to find new ways of delivering first point of contact health care through developing new service models. In common with other areas of rural and regional Australia, the Australian Capital Territory (ACT is currently experiencing a general practitioner (GP workforce shortage which impacts significantly on the ability of patients to access GP led primary care services. The introduction of a nurse led primary care Walk-in Centre in the ACT aimed to fulfill an unmet health care need in the community and meet projected demand for health care services as well as relieve pressure on the hospital system. Stakeholders have the potential to influence health service planning and policy, to advise on the potential of services to meet population health needs and to assess how acceptable health service innovation is to key stakeholder groups. This study aimed to ascertain the views of key stakeholders about the Walk-in Centre. Methods Stakeholders were purposively selected through the identification of individuals and organisations which had organisational or professional contact with the Walk-in Centre. Semi structured interviews around key themes were conducted with seventeen stakeholders. Results Stakeholders were generally supportive of the Walk-in Centre but identified key areas which they considered needed to be addressed. These included the service's systems, full utilisation of the nurse practitioner role and adequate education and training. It was also suggested that a doctor could be available to the Centre as a source of referral for patients who fall outside the nurses' scope of practice. The location of the Centre was seen to impact on patient flows to the Emergency Department. Conclusion Nurse led Walk-in Centres are one response to addressing primary health care medical workforce shortages

  2. The Brief History and Politics of Teacher Led Schools

    Directory of Open Access Journals (Sweden)

    P. S. Myers

    2013-04-01

    Full Text Available Teacher-led, teacher-run, and headless schools are a relatively new reality in American public schooling.  This literature review looks at the work around teacher-run schools and tries to contextualize the theory, history, and opposition to this movement in education.  With little academic writing in the field, this work engages periodicals beyond the peer review process in hopes of providing a well-rounded view and a floor for future scholarship on the topic.

  3. Exploring Service-led Growth Trajectories for Analytical Equipment Providers

    DEFF Research Database (Denmark)

    Raja, Jawwad; Frandsen, Thomas; Mouritsen, Jan

    2016-01-01

    This paper examines the dilemmas encountered by advanced analytical equipment providers in developing service-led growth strategies to expand their business in pursuit of more attractive revenue models. It does so by adopting a case based research approach. The findings detail the capabilities...... and solutions-in different contexts, with a view to expanding markets and developing solution based business models, are discussed. It is argued that analytical equipment providers encounter dilemmas as managing these different trajectories implies different needs in terms of the technological sophistication...

  4. A color management system for multi-colored LED lighting

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Jepsen, Jørgen;

    2015-01-01

    A new color control system is described and implemented for a five–color LED light engine, covering a wide white gamut. The system combines a new way of using pre-calibrated look-up tables and a rule-based optimization of chromaticity distance from the Planckian locus with a calibrated color sensor....... The color sensor monitors the chromaticity of the mixed light providing the correction factor for the current driver by using the generated look-up table. The long term stability and accuracy of the system will be experimentally investigated with target tolerance within a circle radius 0.0011 in the uniform...

  5. Big Data-Led Cancer Research, Application, and Insights.

    Science.gov (United States)

    Brown, James A L; Ni Chonghaile, Triona; Matchett, Kyle B; Lynam-Lennon, Niamh; Kiely, Patrick A

    2016-11-01

    Insights distilled from integrating multiple big-data or "omic" datasets have revealed functional hierarchies of molecular networks driving tumorigenesis and modifiers of treatment response. Identifying these novel key regulatory and dysregulated elements is now informing personalized medicine. Crucially, although there are many advantages to this approach, there are several key considerations to address. Here, we examine how this big data-led approach is impacting many diverse areas of cancer research, through review of the key presentations given at the Irish Association for Cancer Research Meeting and importantly how the results may be applied to positively affect patient outcomes. Cancer Res; 76(21); 6167-70. ©2016 AACR.

  6. Hybrid positioning with lighting LEDs and Zigbee multihop wireless network

    Science.gov (United States)

    Lee, Y. U.; Baang, S.; Park, J.; Zhou, Z.; Kavehrad, M.

    2012-01-01

    A simple, accurate, secure, long-lasting, and portable hybrid positioning system is proposed and designed in this paper. It consists of a lighting LED that generates visible light data corresponding to position information of a target and a Zigbee wireless network communication module with low power, security, and service area expansion characteristics. Under an indoor environment where there is 23.62m distance between an observer and the target, the presented hybrid positioning system is tested and is verified with the functions of Zigbee three hop wireless networking and visible light communication (VLC) scheme. The test results are analyzed and discussed.

  7. A lifetime prediction method for LEDs considering mission profiles

    DEFF Research Database (Denmark)

    Qu, Xiaohui; Wang, Huai; Zhan, Xiaoqing

    2016-01-01

    and to benchmark the cost-competitiveness of different lighting technologies. The existing lifetime data released by LED manufacturers or standard organizations are usually applicable only for specific temperature and current levels. Significant lifetime discrepancies may be observed in field operations due...... to the varying operational and environmental conditions during the entire service time (i.e., mission profiles). To overcome the challenge, this paper proposes an advanced lifetime prediction method, which takes into account the field operation mission profiles and the statistical properties of the life data...

  8. Development of LED light sources and lamps. Final report; Slutrapport for PSO 337-068. Udvikling af LED lyskilder og lamper

    Energy Technology Data Exchange (ETDEWEB)

    Dam-Hansen, C.; Petersen, Paul Michael; Thestrup, B.; Scharling Holm, J.; Munkgaard Andersen, J.; Falleboe, H.; Olsen, Jesper; Flindt, C.

    2007-04-15

    This report is the final and concluding report on the research and development project 'Development of LED light sources and lamps' PSO no. 337-068 supported by Dansk Energi - Net. The project was a collaboration between Risoe National laboratory, Louis Poulsen Lighting, Dong Energy, Laboratoriet Lys & Syn and RGB Lamps. The objective of this project was to pave the way for replacement of incandescent- and halogen lighting by LED lightning through development of prototypes for new types of LED products: light sources and lamps. The report summarizes and describes the main results of the project, which are: 1) a new LED light source with an efficacy of 51 lm/W and a CRI index of 92 that can replace an incandescent bulb. 2) two LED pendants/lamps, a LED table lamp and a chair with LED lighting developed by designers and researchers. 3) LED seminar and two exhibitions of the newly developed LED products and user test by questionnaires. 4) A new startup company 'Morfoso'. 5) Developed course on light and LED technology for designers. 6) A new LED light laboratory for test and characterization of LED components and LED light sources and lamps. (au)

  9. The establishment of reliability model for LED lamps

    Science.gov (United States)

    Jian, Hao; Lei, Jing; Yao, Wang; Qun, Gao; Hongliang, Ke; Xiaoxun, Wang; Yanchao, Zhang; Qiang, Sun; Zhijun, Xu

    2016-07-01

    In order to verify which of the distributions and established methods of reliability model are more suitable for the analysis of the accelerated aging of LED lamp, three established methods (approximate method, analytical method and two-stage method) of reliability model are used to analyze the experimental data under the condition of the Weibull distribution and Lognormal distribution, in this paper. Ten LED lamps are selected for the accelerated aging experiment and the luminous fluxes are measured at an accelerated aging temperature. AIC information criterion is adopted in the evaluation of the models. The results show that the accuracies of the analytical method and the two-stage method are higher than that of the approximation method, with the widths of confidence intervals of unknown parameters of the reliability model being the smallest for the two-stage method. In a comparison between the two types of distributions, the accuracies are nearly identical. Project supported by the National High Technology Research and Development Program of China (Nos. 2015AA03A101, 2013AA03A116), the Cuican Project of Chinese Academy of Sciences (No. KZCC-EW-102), and the Jilin Province Science and Technology Development Plan Item (No. 20130206018GX).

  10. LED Curing Lights and Temperature Changes in Different Tooth Sites

    Directory of Open Access Journals (Sweden)

    E. Armellin

    2016-01-01

    Full Text Available Objectives. The aim of this in vitro study was to assess thermal changes on tooth tissues during light exposure using two different LED curing units. The hypothesis was that no temperature increase could be detected within the dental pulp during polymerization irrespective of the use of a composite resin or a light-curing unit. Methods. Caries-free human first molars were selected, pulp residues were removed after root resection, and four calibrated type-J thermocouples were positioned. Two LED lamps were tested; temperature measurements were made on intact teeth and on the same tooth during curing of composite restorations. The data was analyzed by one-way analysis of variance (ANOVA, Wilcoxon test, Kruskal-Wallis test, and Pearson’s χ2. After ANOVA, the Bonferroni multiple comparison test was performed. Results. Polymerization data analysis showed that in the pulp chamber temperature increase was higher than that without resin. Starlight PRO, in the same condition of Valo lamp, showed a lower temperature increase in pre- and intrapolymerization. A control group (without composite resin was evaluated. Significance. Temperature increase during resin curing is a function of the rate of polymerization, due to the exothermic polymerization reaction, the energy from the light unit, and time of exposure.

  11. Online and offline peer led models against bullying and cyberbullying.

    Science.gov (United States)

    Palladino, Benedetta Emanuela; Nocentini, Annalaura; Menesini, Ersilia

    2012-11-01

    The aim of the present study is to describe and evaluate an ongoing peer-led model against bullying and cyberbullying carried out with Italian adolescents. The evaluation of the project was made through an experimental design consisting of a pre-test and a post-test. Participants in the study were 375 adolescents (20.3% males), enrolled in 9th to 13th grades. The experimental group involved 231 students with 42 peer educators, and the control group involved 144 students. Results showed a significant decrease in the experimental group as compared to the control group for all the variables except for cyberbullying. Besides, in the experimental group we found a significant increase in adaptive coping strategies like problem solving and a significant decrease in maladaptive coping strategies like avoidance: these changes mediate the changes in the behavioural variables. In particular, the decrease in avoidance predicts the decrease in victimization and cybervictimization for peer educators and for the other students in the experimental classes whereas the increase in problem solving predicts the decrease in cyberbullying only in the peer educators group. Results are discussed following recent reviews on evidence based efficacy of peer led models.

  12. Miniaturized LED sources for in vivo optogenetic experimentation

    Science.gov (United States)

    Clements, Isaac P.; Gnade, Andrew G.; Rush, Alexander D.; Patten, Craig D.; Twomey, Mark C.; Kravitz, Alexxai V.

    2013-03-01

    Recently developed optogenetics techniques have enabled researchers to modulate the activity of specific cell types. As a result, complex neural pathways previously regarded as black boxes can now be directly probed, yielding a steadily increasing understanding of the basic neural circuits that underlie health and disease. For in vivo experimentation, fiber-coupled lasers have traditionally been used to illuminate internal brain regions, via an optical fiber that penetrates through overlying tissue. Though able to deliver intense fiber-coupled light, lasers are costly, bulky, and face limitations in output beam stability and temporal precision during modulated outputs. For experiments on unrestricted, behaving animals, a laser-based system also necessitates the use of fiber optic rotary joints, which come with costs and limitations of their own. Here, we report and characterize an alternative light delivery solution, based on high intensity fiber-coupled LEDs that are miniaturized for placement on the end of custom electrical commutators. This design allows for enhanced control of output light and expanded capabilities for optical stimulation as well as simultaneous electrical neural recordings, as with an optrode array. Temporal response of light outputs and light stability during commutator rotation were assessed. The influence of high current optical control signals on adjacent neural recording channels was also explored. To validate the function of this LED based system in in vivo recording scenarios, chronic stimulation experiments were performed.

  13. Design method for automotive high-beam LED optics

    Science.gov (United States)

    Byzov, Egor V.; Moiseev, Mikhail A.; Doskolovich, Leonid L.; Kazanskiy, Nikolay L.

    2015-09-01

    New analytical method for the calculation of the LED secondary optics for automotive high-beam lamps is presented. Automotive headlamps should illuminate the road and the curb at the distance of 100-150 meters and create a bright, flat, relatively powerful light beam. To generate intensity distribution of this kind we propose to use TIR optical element (collimator working on the total internal reflection principle) with array of microlenses (optical corrector) on the upper surface. TIR part of the optical element enables reflection of the side rays to the front direction and provides a collimated beam which incidents on the microrelief. Microrelief, in its turn, dissipates the light flux in horizontal direction to meet the requirements of the Regulations 112, 113 and to provide well-illuminated area across the road in the far field. As an example, we computed and simulated the optical element with the diameter of 33 millimeters and the height of 22 millimeters. Simulation data shows that three illuminating modules including Cree XP-G2 LED and lens allow generating an appropriate intensity distribution for the class D of UNECE Regulations.

  14. Chemical sensors

    Science.gov (United States)

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1991-07-02

    Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

  15. Monolithic integration of Si-MOSFET and GaN-LED using Si/SiO2/GaN-LED wafer

    Science.gov (United States)

    Tsuchiyama, Kazuaki; Yamane, Keisuke; Utsunomiya, Shu; Sekiguchi, Hiroto; Okada, Hiroshi; Wakahara, Akihiro

    2016-10-01

    In this report, we present a monolithic integration method for a Si-MOSFET and a GaN-LED onto a Si/SiO2/GaN-LED wafer as an elemental technology for monolithic optoelectronic integrated circuits. To enable a Si-MOSFET device process, we investigated the thermal tolerance of a thin top-Si and GaN-LED layer on a Si/SiO2/GaN-LED wafer. The high thermal tolerance of the Si/SiO2/GaN-LED structure allowed for the monolithic integration of a Si n-MOSFET and a GaN-µLED without degrading the performance of either device. A GaN-µLED driver circuit was fabricated using a Si n-MOSFET and a µLED of 30 × 30 µm2, with the modulation bandwidth of the circuit estimated to be over 10 MHz.

  16. Analysis of the Drive Circuit Problem of LED Road Lamp%LED 路灯驱动电路问题分析

    Institute of Scientific and Technical Information of China (English)

    孟繁春

    2015-01-01

    介绍了 LED 光源特点,分析了 LED 路灯驱动电路的设计要求,以及常用驱动电路存在的问题。%The characteristics of LED light source were introduced in the paper.The design requirement of the drive circuit of LED road lamp was analyzed.And the existing problems of the drive circuit were presented.

  17. DMPonline Version 4.0: User-Led Innovation

    Directory of Open Access Journals (Sweden)

    Magdalena Getler

    2014-07-01

    Full Text Available DMPonline is a web-based tool to help researchers and research support staff produce data management and sharing plans. Between October and December 2012, we examined DMPonline in unprecedented detail. The results of this evaluation led to some major changes. We have shortened the DCC Checklist for a Data Management Plan and revised how this is used in the tool. We have also amended the data model for DMPonline, improved workflows and redesigned the user interface. This paper reports on the evaluation, outlining the methods used, the results gathered and how they have been acted upon. We conducted usability testing on v.3 of DMPonline and the v.4 beta prior to release. The results from these two rounds of usability testing are compared to validate the changes made. We also put forward future plans for a more iterative development approach and greater community input.

  18. An Insurance-Led Response to Climate Change

    CERN Document Server

    Webster, Anthony J

    2015-01-01

    Climate change is widely expected to increase weather related damage and the insurance claims that result from it. This has the undesirable consequence of increasing insurance costs, in a way that is independent of a customer's contribution to the causes of climate change. This is unfortunate because insurance provides a financial mechanism that mitigates some of the consequences of climate change, allowing damage from increasingly frequent events to be repaired. We observe that the insurance industry could reclaim any increase in claims due to climate change, by increasing the insurance premiums on energy producers for example, without needing government intervention or a new tax. We argue that this insurance-led levy must acknowledge both present carbon emissions and a modern industry's carbon inheritance, that is, to recognise that fossil-fuel driven industrial growth has provided the innovations and conditions needed for modern civilisation to exist and develop. The increases in premiums would initially b...

  19. CJFA Delegation Led by Song Jian Visits Japan

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>At the invitation of the Japan-China Friendship Centre,a delegation of the China-Japan Friendship Association(CJFA) led by its President Song Jian paid a goodwill visit to Japan from December 3 to 10,2006.In Tokyo Song Jian and his party paid an official call on leaders of the Japanese ruling party and parties not in office and a number of important political figures including Prime Minister Shinzo Abe,Speaker of the House of Representatives Yohei Kono,Foreign Minister Taro Aso,head of the New Komeito Party Akihiro Ota,leader of the Democratic Party Ichiro Ozawa,Chairman of the Central Committee of the Communist Party of Japan Kazuo Shii,and Chairman of the Socialist Party Mizuho Fukushima,and fully exchanged views with the leaders of the seven Japan-China friendship organizations on making great efforts to promote people-to-people friendly exchanges.

  20. LED pumped Nd:YAG laser development program

    Science.gov (United States)

    Farmer, G. I.; Kiang, Y. C.; Lynch, R. J.

    1973-01-01

    The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

  1. Application of Remote FPGA Dynamic Reconfiguration System in LED Lighting

    Institute of Scientific and Technical Information of China (English)

    LI Wei; WANG Wei; NIU Ping-juan; ZHANG li-ping

    2009-01-01

    The dynamic reconfiguration technique based on field-programmable gate array (FPGA) can improve the resource utilization.Discussed are the dynamic reconfiguration principles and methods.Proposed is a remote dynamic reconfiguration scheme using Xilinx Virtex-II FPGA and SMCS Ethernet Physical layer transceiver(PHY).The hardware of the system is designed with Xilinx Virtex-II XC2V30P FPGA that embedds MicroBlaze and MAC IP core,and its network communication software based on transmission control protocol/Internet protocol (TCP/IP) protocol is programmed by loading LwlP to MicroBlaze. The experimental results indicate that the remote FPGA dynamic reconfiguration system(RFDRS) can switch freely in the eight lighting modes of light emitting diodes (LED),and that,using dynamic reconfiguration technology,FPGA resource utilization can be reduced remarkably,which is advantageous in the system upgrade and software update.

  2. LED-Absorption-QEPAS Sensor for Biogas Plants

    Directory of Open Access Journals (Sweden)

    Michael Köhring

    2015-05-01

    Full Text Available A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors; it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors.

  3. Processing Decoded Video for LCD-LED Backlight Display

    DEFF Research Database (Denmark)

    Nadernejad, Ehsan

    algorithms for signal (image or video) enhancement. One particular application of such algorithms is the case of LCDs with dynamic local backlight. The thesis addressed two main problems; first, designing algorithms that improve the visual quality of perceived image and video and reduce power consumption...... on local LED-LCD backlight. Second, removing the digital video codec artifacts such as blocking and ringing artifacts by post-processing algorithms. A novel algorithm based on image features with optimal balance between visual quality and power consumption was developed. In addition, to remove flickering......The quality of digital images and video signal on visual media such as TV screens and LCD displays is affected by two main factors; the display technology and compression standards. Accurate knowledge about the characteristics of display and the video signal can be utilized to develop advanced...

  4. LED Lightbulbs as a Source of Electricity Saving in Buildings

    Directory of Open Access Journals (Sweden)

    Zeb Akhtar

    2016-01-01

    Full Text Available Today a number of renewable energy technologies are available for power generation, but fossil fuels are still providing a dominant share nevertheless. In order to decrease the electric bill and save our environment, energy conservation is always crucial. In this paper a very interesting idea is presented which is economically viable to reduce electricity usage in our buildings. An effort has been made to estimate the amount of energy that could be saved in the dormitory section of the IMOP building in Russia. Although there are many ways to reduce the consumption of electricity in this building but here the emphasis is on changing light bulbs inside the rooms, kitchen, toilet and bathroom of each apartment. The scope of the study is to figure out monthly electricity saving by replacing traditional light bulbs by LED light bulbs in the building under consideration. The total investment required and the payback period is also presented.

  5. Confocal spectroscopy of InGaN LED structures

    Energy Technology Data Exchange (ETDEWEB)

    Dobrovolskas, D; Mickevicius, J; Kuokstis, E; Tamulaitis, G [Semiconductor Physics Department and Institute of Applied Research, Vilnius University, Sauletekio 9-III, LT-10222 Vilnius (Lithuania); Shur, M [Department of Electrical, Computer, and Systems Engineering, and Center of Integrated Electronics, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Shatalov, M; Yang, J; Gaska, R, E-mail: darius.dobrovolskas@ff.stud.vu.l [Sensor Electronic Technology, Inc., 1195 Atlas Road, Columbia, SC (United States)

    2011-04-06

    Photoluminescence of InGaN structures for green light-emitting diodes (LEDs) with multiple quantum wells as an active medium was studied with spatial and spectral resolution using confocal microscopy. Bright spots of {approx}200 nm diameter were observed. Emission from these bright areas was up to 8 times more intense than from the rest of the sample surface and the band peak position in these areas was blueshifted with respect to the band position in the background surface of lower photoluminescence intensity. The data on emission properties in bright and dark areas and the dependence of these properties on the excitation power density were interpreted by assuming inhomogeneous distribution of defects acting as nonradiative recombination centres.

  6. LED-Absorption-QEPAS Sensor for Biogas Plants.

    Science.gov (United States)

    Köhring, Michael; Böttger, Stefan; Willer, Ulrike; Schade, Wolfgang

    2015-05-22

    A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors; it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors.

  7. Developing an advanced practice nurse-led liver clinic.

    Science.gov (United States)

    McAfee, Jean L

    2012-01-01

    End-stage liver disease (ESLD) is a leading cause of digestive disease deaths in the United States and continues to increase exponentially every year. Best practice does not currently recognize or utilize a clinic practice model for ESLD management. Advanced practice registered nurses (APRNs) can impact ESLD disease management by implementing an outpatient clinic care model to focus on treatment compliance, patient education, improvement of patient outcomes, and reduction in hospital admission rates for ESLD patients. A review of 15 research articles was completed to determine the impact APRNs can make on chronic care of ESLD patients. Results from the review support APRN analysis, assessment, diagnosis, treatment, intervention, and evaluation of ESLD patients. The literature reviewed also demonstrates that ESLD patients have improved symptom management when maintained in an outpatient setting, allowing for decreased hospital and insurance expenditures. Following evaluation of the evidence, it was concluded that an APRN-led ESLD clinic merits further study.

  8. Youth-Led Participatory Action Research: Developmental and Equity Perspectives.

    Science.gov (United States)

    Ozer, Emily J

    2016-01-01

    Youth-led participatory action research (YPAR) is an approach to scientific inquiry and social change grounded in principles of equity that engages young people in identifying problems relevant to their own lives, conducting research to understand the problems, and advocating for changes based on research evidence. This chapter provides an introduction to YPAR followed by consideration of the (a) developmental relevance of YPAR for marginalized youth, (b) implications of YPAR for developmental science research on inequities experienced by youth, and (c) potential opportunities and impact of YPAR for improving key developmental settings such as schools and youth-serving organizations. Resources for conducting YPAR projects are discussed, as well as the need for potential integration of YPAR and other participatory approaches to engaging youth and their expertise-at a significant enough scale to have a meaningful impact on policies and practices that affect youth development.

  9. Analysis of LED degradation; proton-bombarded GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Hooft, G.W. ' t; Opdorp, C. van (Philips Gloeilampenfabrieken N.V., Eindhoven (Netherlands). Forschungslaboratorium)

    1984-03-01

    An analysis is given of the degradation of light-emitting, Zn-diffused GaAs diodes after proton bombardment. Use is made of a generally applicable method by which the external bulk quantum efficiency and the injection efficiency of an LED can be determined separately. Owing to the increase of non-radiative recombination being larger in the bulk than in the space-charge region, the injection efficiency at constant current first starts to increase and then decreases as a function of irradiation fluence. Furthermore, it is shown that the apparent bulk quantum efficiency decreases superlinearly with the irradiation fluence. This is consistent with the theory for a linear-graded pn junction and the assumption that the concentration of additional killer centres is directly proportional to the irradiation fluence.

  10. Current-voltage model of LED light sources

    DEFF Research Database (Denmark)

    Beczkowski, Szymon; Munk-Nielsen, Stig

    2012-01-01

    -emitting diode devices, presented in this paper, creates a way to estimate diode's colorimetric properties based on driving current and diode's voltage. The accuracy of the model was tested under direct and pulsed driving current. For DC current, the color difference between the modeled color point of the diode......Amplitude modulation is rarely used for dimming light-emitting diodes in polychromatic luminaires due to big color shifts caused by varying magnitude of LED driving current and nonlinear relationship between intensity of a diode and driving current. Current-voltage empirical model of light...... and the actual measured one, is much lower than the just noticeable color difference (mean ΔEab* = 0.15). The model can be used e.g. as a color feedback mechanism in high power trichromatic luminaires such as profile lamps....

  11. Spectral image reconstruction by a tunable LED illumination

    Science.gov (United States)

    Lin, Meng-Chieh; Tsai, Chen-Wei; Tien, Chung-Hao

    2013-09-01

    Spectral reflectance estimation of an object via low-dimensional snapshot requires both image acquisition and a post numerical estimation analysis. In this study, we set up a system incorporating a homemade cluster of LEDs with spectral modulation for scene illumination, and a multi-channel CCD to acquire multichannel images by means of fully digital process. Principal component analysis (PCA) and pseudo inverse transformation were used to reconstruct the spectral reflectance in a constrained training set, such as Munsell and Macbeth Color Checker. The average reflectance spectral RMS error from 34 patches of a standard color checker were 0.234. The purpose is to investigate the use of system in conjunction with the imaging analysis for industry or medical inspection in a fast and acceptable accuracy, where the approach was preliminary validated.

  12. Reported challenges in nurse-led randomised controlled trials

    DEFF Research Database (Denmark)

    Wang Vedelø, Tina; Lomborg, Kirsten

    2011-01-01

    , nursing research, nursing, research, challenges, barriers, nurse's role, nurse attitude, attitude of health personnel. Findings: The literature on reported challenges and barriers between 1999 and 2009 showed that the most often experienced problems were (i) sufficient patient recruitment, (ii......Aims: The purpose of this integrative literature review was to explore and discuss the methodological challenges nurse researchers report after conducting nurse-led randomised controlled trials in clinical hospital settings. Our research questions were (i) what are the most commonly experienced...... and the clinical nursing staff. Two lessons learned from this integrative review can be highlighted. First, we recommend researchers openly to share their experiences of barriers and challenges. They should describe factors that may have inhibited the desired outcome. Second, efforts to improve the collaboration...

  13. Chemical intolerance

    DEFF Research Database (Denmark)

    Dantoft, Thomas Meinertz; Andersson, Linus; Nordin, Steven;

    2015-01-01

    Chemical intolerance (CI) is a term used to describe a condition in which the sufferer experiences a complex array of recurrent unspecific symptoms attributed to low-level chemical exposure that most people regard as unproblematic. Severe CI constitutes the distinguishing feature of multiple...... chemical sensitivity (MCS). The symptoms reported by CI subjects are manifold, involving symptoms from multiple organs systems. In severe cases of CI, the condition can cause considerable life-style limitations with severe social, occupational and economic consequences. As no diagnostic tools for CI...

  14. Hazardous Chemicals

    Centers for Disease Control (CDC) Podcasts

    2007-04-10

    Chemicals are a part of our daily lives, providing many products and modern conveniences. With more than three decades of experience, The Centers for Disease Control and Prevention (CDC) has been in the forefront of efforts to protect and assess people's exposure to environmental and hazardous chemicals. This report provides information about hazardous chemicals and useful tips on how to protect you and your family from harmful exposure.  Created: 4/10/2007 by CDC National Center for Environmental Health.   Date Released: 4/13/2007.

  15. Analysis of Student Performance in Peer Led Undergraduate Supplements

    Science.gov (United States)

    Gardner, Linda M.

    Foundations of Chemistry courses at the University of Kansas have traditionally accommodated nearly 1,000 individual students every year with a single course in a large lecture hall. To develop a more student-centered learning atmosphere, Peer Led Undergraduate Supplements (PLUS) were introduced to assist students, starting in the spring of 2010. PLUS was derived from the more well-known Peer-Led Team Learning with modifications to meet the specific needs of the university and the students. The yearlong investigation of PLUS Chemistry began in the fall of 2012 to allow for adequate development of materials and training of peer leaders. We examined the impact of academic achievement for students who attended PLUS sessions while controlling for high school GPA, math ACT scores, credit hours earned in high school, completion of calculus, gender, and those aspiring to be pharmacists (i.e., pre-pharmacy students). In a least linear squares multiple regression, PLUS participants performed on average one percent higher on exam scores for Chemistry 184 and four tenths of a percent on Chemistry 188 for each PLUS session attended. Pre-pharmacy students moderated the effect of PLUS attendance on chemistry achievement, ultimately negating any relative gain associated by attending PLUS sessions. Evidence of gender difference was demonstrated in the Chemistry 188 model, indicating females experience a greater benefit from PLUS sessions. Additionally, an item analysis studied the relationship between PLUS material to individual items on exams. The research discovered that students who attended PLUS session, answered the items correctly 10 to 20 percent more than their comparison group for PLUS interrelated items and no difference to 10 percent for non-PLUS related items. In summary, PLUS has a positive effect on exam performance in introductory chemistry courses at the University of Kansas.

  16. The effects of bluephase LED light on fibroblasts

    Science.gov (United States)

    Malčić, Ana Ivanišević; Pavičić, Ivan; Trošić, Ivančica; Simeon, Paris; Katanec, Davor; Krmek, Silvana Jukić

    2012-01-01

    Objective: The aim of this study was to evaluate the effect of Bluephase light emitting diode (LED) light on cell viability, colony-forming ability and proliferation in V79 cell culture and to determine how much the temperature of the nutrient medium rose. Methods: The investigation included a low (L), soft start (S) and high (H) illumination mode for 20, 40 and 80 seconds. The viability was determined by the trypan blue exclusion test, colony-forming ability by counting colonies 7 days after exposure and cell proliferation by the cell counts on 5 post-exposure days. The temperature change during illumination was recorded (0.1°C sensitivity). Results: In each experimental condition, 90–95% of the cells were viable, which was in the same range as the controls. Colony-forming ability was not found to be significantly lower (P<.05). A significant decrease in proliferation was recorded on the 4th post-exposure day with S and H irrespective of time, on the 3rd day with S for 80 s and H for 40 and 80 s, and with S and H for 80 s on the 2nd day (P<.05).The temperature rise was significant with S (P<.05) and H (P<.05), irrespective of exposure duration. Conclusion: Dependent on total energy density, LED blue light affects the mitotic activity of cells in its path to a certain extent. Altered mitotic activity was not noted with illumination at the low power mode (intensity of 421.7 ±1.1 mW/cm2). The greatest temperature rise was 8.3 °C and occurred at the highest intensity and exposure duration. PMID:22904660

  17. Nonlinear Dimming and Correlated Color Temperture Control of Bi-Color White LED Systems

    OpenAIRE

    Chen, H; Tan, SC; Hui, SYR

    2015-01-01

    This paper proposes a nonlinear approach of controlling the luminous intensity and correlated color temperature (CCT) of white light-emitting diode (LED) systems with dual color temperatures. This LED system is made up of a warm color LED source (2700 K) and a cool color LED source (5000 K). The luminous intensity of each of these LED sources is individually controlled by pulsewidth modulation. The overall intensity of the LED system is due to the combined emitted flux of both LED sources. It...

  18. Short-wavelength light beam in situ monitoring growth of InGaN/GaN green LEDs by MOCVD.

    Science.gov (United States)

    Sun, Xiaojuan; Li, Dabing; Song, Hang; Chen, Yiren; Jiang, Hong; Miao, Guoqing; Li, Zhiming

    2012-05-31

    In this paper, five-period InGaN/GaN multiple quantum well green light-emitting diodes (LEDs) were grown by metal organic chemical vapor deposition with 405-nm light beam in situ monitoring system. Based on the signal of 405-nm in situ monitoring system, the related information of growth rate, indium composition and interfacial quality of each InGaN/GaN QW were obtained, and thus, the growth conditions and structural parameters were optimized to grow high-quality InGaN/GaN green LED structure. Finally, a green LED with a wavelength of 509 nm was fabricated under the optimal parameters, which was also proved by ex situ characterization such as high-resolution X-ray diffraction, photoluminescence, and electroluminescence. The results demonstrated that short-wavelength in situ monitoring system was a quick and non-destroyed tool to provide the growth information on InGaN/GaN, which would accelerate the research and development of GaN-based green LEDs.

  19. The effect of radiation of LED modules on the growth of dill (Anethum graveolens L.

    Directory of Open Access Journals (Sweden)

    Frąszczak Barbara

    2016-01-01

    Full Text Available Light quality is thought to affect the growth and development of plants. We examined how light influences the growth and content of some chemical compounds in dill (Anethum graveolens L.. The plants were grown under different light quality. The share of orange and green light in the spectrum was constant and amounted to 10% for either colour. In the first combination (A, 70/10, there was 70% of red light and 10% of blue light. Other combinations had the following proportions: B 60/20, C 50/30, D 40/40 and E 30/50 of red and blue light. The PPFD was about 155 μmol m-2 s-1. Blue light inhibited the elongation growth as well as leaf area. It had positive influence on the accumulation of dry mass, glucose and fructose in the herb. In the combinations with higher percentage of red light the plants were characterised by higher content of essential oils, macronutrients and zinc. To sum up, we can say that the proportion of red and blue light has significant influence on the morphological qualities, chemical composition and dynamics of photosynthesis in these plants. On the other hand, the selection of spectral composition of LEDs will depend on the result we want to achieve.

  20. High Efficiency SEPIC Converter For High Brightness Light Emitting Diodes (LEDs) System

    OpenAIRE

    Qin, Yaxiao

    2012-01-01

    ABSTRACT This thesis presents an investigation into the characteristics of and driving methods for light emitting diode (LED) lamp system. A comprehensive overview on the lighting development is proposed. The characteristic of the light emitting diode (LED) lamp is described and the requirements of the ballast for the light emitting diode (LED) lamp are presented. Although LED lamps have longer lifetime than fluorescent lamps, the short lifetime limitation of LED driver imposed by ele...

  1. Led PCB thermal simulation using FloEFD

    OpenAIRE

    Andonova, A.

    2012-01-01

    В статье представлены результаты создания корпусов светодиодов (LED) высокой мощности на основе печатной платы и двойного слоя стеклотекстолита FR4. Прежде всего, создается детализированная модель корпуса LED на подложке. Затем модель оптимизируется с учетом вида, количества и расположения тепловых межслойных соединений, ширины тепловых каналов и рассеиваемой мощности...

  2. Research on IC Driver Used in Automotive LED Lighting%可用于汽车 LED 照明系统的驱动 IC 研究

    Institute of Scientific and Technical Information of China (English)

    司小平

    2015-01-01

    This paper introduces the specific requirements of high power LED lighting IC uses in vehicles.With classic LED drivers from several famous IC companies as an example,current situation of automotive LED lighting driver is illus-trated.Typical high power automotive LED lighting drivers at home and abroad are compared in aspects of parameters, suitable topology and footprint.Finally,prospects of automotive LED lighting driving IC are outlined.%文中介绍了车用大功率 LED 照明 IC 的具体要求,以几个著名 IC 生产设计公司的经典 LED 驱动器为例说明了汽车 LED 照明驱动芯片现状,从性能参数、适用拓扑、封装形式等方面对目前国内外具有代表性的大功率车用 LED 驱动芯片作了比较和研究,并对车用 LED 照明驱动 IC 进行了展望。

  3. Polychromatic white LED using GaN nano pyramid structure

    Science.gov (United States)

    Kim, Taek; Kim, Jusung; Yang, Moonseung; Park, Yongsoo; Chung, U.-In; Ko, Yongho; Cho, Yonghoon

    2013-03-01

    We have developed monolithic white light emitting diodes (LEDs) with a hybrid structure of planar c-planes and nano size hexagonal pyramids. The white spectrum is composed of blue and yellow emissions from the InGaN multi quantum wells (MQWs) on the planar c-planes and on the nano pyramids, respectively. The yellow emission is originated from quantum wells, wires, and dots that are formed at the sides, edges, and tops of the nano-pyramids, respectively. As a result, the emission peaks are different and the entire yellow spectrum is broad enough to make a white in combination with a blue emission. The longer wavelength from the InGaN on nano-pyramids than the wavelength from the InGaN on c-planes is explained by excess In supply from the dielectric selective growth mask. The color temperature is tuned from 3600K to 6400K by controlling the relative area ratio of c-plane and nano-pyramids.

  4. Patterns of Light Chasing the Spectrum from Aristotle to LEDs

    CERN Document Server

    Beeson, Steven

    2008-01-01

    Light is all around us – even when we do not see it. Our eyes do not detect the higher energy and shorter-than-visible-wavelength ultraviolet radiation, yet we know it is there from the sunburn we receive in Arizona. We know that window glass can block ultraviolet rays so we do not get a burn while driving with the windows rolled up. Our eyes do not detect the low-energy, long-wavelength infrared (IR) radiation but we know it exists from discussions of war applications and televised images of guided weapons targets. We also know about radio waves from the little boxes that talk to us and x-rays from the dentist's office. Patterns of Light, Chasing the Spectrum from Aristotle to LEDs, written by Steve Beeson and Jim Mayer starts with the visible – the straight path of light. It continues with chapters detailing reflection (mirrors, storefront windows) and refraction (eyeglasses, binoculars). Color is then introduced with the query "Why is the sky blue?" After answering that and other similar questions ("Wh...

  5. Pharmacist-led medication review in an acute admissions unit

    DEFF Research Database (Denmark)

    Hansen, Trine Graabæk; Bonnerup, Dorthe Krogsgaard; Kjeldsen, Lene Juel;

    2015-01-01

    Objectives Over the last decades, several papers have evaluated clinical pharmacy interventions in hospital settings with conflicting findings as results. Medication reviews are frequently a central component of these interventions. However, the term ‘medication review’ covers a plethora of princ......, not to provide or advocate a single one-size-fits-all solution, but in an attempt to inspire a debate of the practical approach on how to execute a systematic medication review in order to develop and expand clinical pharmacy and achieve better patient outcomes.......Objectives Over the last decades, several papers have evaluated clinical pharmacy interventions in hospital settings with conflicting findings as results. Medication reviews are frequently a central component of these interventions. However, the term ‘medication review’ covers a plethora...... of principles and methodologies, and the practical procedure is seldom described in detail, which makes reproducing study findings difficult. The objective of this paper is to provide a detailed description of a procedure developed and used for pharmacist-led medication review in acute admissions units...

  6. LED Based Optical Wireless Communication System for WBAN

    Directory of Open Access Journals (Sweden)

    ATTIYA BAQAI

    2016-10-01

    Full Text Available In this paper the O-WBANs (Optical Wireless Body Area Networks is presented as an alternative to the radio and microwave BANs which are plagued with issues like interference, power hungry, hazardous and costly spectrum. Various experiments performed in this work demonstrate the feasibility of LED (Light-Emitting Diode based optical systems to be used for BANs. The system cost is kept as low as possible. Mainly the effects on the optical link are observed under ambient light and with different modulation schemes by varying link distance and line of sight in this paper. Experimental results reveal the satisfactory link availability up to the distance of 7 feet (around 2m, the optimum range of WBAN and within the field of view of 30-60º. The low cost solution presented in this paper meets the WBANs data rate requirement for physiological data (i.e. 10-100 kbps. As IR (Infra-Red signals do not provide any interference with the signals generated by the medical equipment of hospitals which is the problem in case of RF or microwave signals, additionally the IR signals are confined within a room hence IR signaling can prove to be potential candidate for WBAN fulfilling its security and limited access requirement.

  7. LED-based near infrared sensor for cancer diagnostics

    Science.gov (United States)

    Bogomolov, Andrey; Ageev, Vladimir; Zabarylo, Urszula; Usenov, Iskander; Schulte, Franziska; Kirsanov, Dmitry; Belikova, Valeria; Minet, Olaf; Feliksberger, E.; Meshkovsky, I.; Artyushenko, Viacheslav

    2016-03-01

    Optical spectroscopic technologies are increasingly used for cancer diagnostics. Feasibility of differentiation between malignant and healthy samples of human kidney using Fluorescence, Raman, MIR and NIR spectroscopy has been recently reported . In the present work, a simplification of NIR spectroscopy method has been studied. Traditional high-resolution NIR spectrometry was replaced by an optical sensor based on a set of light-emitting diodes at selected wavelengths as light sources and a photodiode. Two prototypes of the sensor have been developed and tested using 14 in-vitro samples of seven kidney tumor patients. Statistical evaluation of results using principal component analysis and partial least-squares discriminant analysis has been performed. Despite only partial discrimination between tumor and healthy tissue achieved by the presented new technique, the results evidence benefits of LED-based near-infrared sensing used for oncological diagnostics. Publisher's Note: This paper, originally published on 4 March, 2016, was replaced with a corrected/revised version on 7 April, 2016. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.

  8. Introducing Midwifery-led Birth Centres to Ontario

    Directory of Open Access Journals (Sweden)

    Cristina A. Mattison

    2015-03-01

    Full Text Available In Ontario, maternal health systems are changing, with an increasing variety of childbirth options being offered to low-risk pregnant women. Midwifery became a regulated profession in the province in 1994: providing primary care throughout pregnancy, labour and for up to six weeks postpartum. Currently there are three midwifery-led birth centres operating in Ontario, two of which opened in early 2014. The Ministry of Health and Long-Term Care (MoHLTC has launched these new birth centres in order to offer women more choice in health care provider and birth setting. This shift is representative of the MoHLTC’s push to move services out of hospitals and into community-based settings. While the birth centre initiative is in its early stages and a formal program evaluation is needed, it has the potential, if scaled up, to decrease the need for hospital beds as well as reduce health care costs through more appropriate care for low-risk pregnancies, leading to fewer interventions.

  9. Enhancing Algal Growth by Stimulation with LED Lighting and Ultrasound

    Directory of Open Access Journals (Sweden)

    Shao-Yi Hsia

    2015-01-01

    Full Text Available Algae are not only rich in natural nutrients, but are also a high-priced health food. An important constituent called “growth factor” is extracted from algae and used as an ingredient in medical drugs, foods, cosmetics, and other products. Its enormous potential market should not be taken lightly. Algae are mostly found near coastal areas and their habitats are limited by a number of natural factors, leading to large labor and financial expenditures to harvest. This report describes our study of indoor algae production using LED lights and ultrasound and manipulating other growth factors at different temperatures. Ultrasound treatment at the alga’s natural resonant frequency was varied to determine optimal algal growth using the Taguchi method to plan and to analyze the experiments. The results were very satisfying, showing an 8.23% increase in the growth rate by the fifth day due to ultrasound treatment and an amazing 27.01% growth rate due to biomechanical stimulation.

  10. Speech therapist led voice clinic: which patients may be suitable?

    Science.gov (United States)

    Vaghela, Hersad M; Fergie, Neil; Slade, Suzanne; McGlashan, Julian A

    2005-01-01

    Joint Voice clinics run by an ENT surgeon (Laryngologist) and Voice therapist avoid repetition of clinical assessment, better planning of patient management and early initiation of treatment. Although is perceived as optimal management of voice patients it is perhaps not necessary for all patients as it is time consuming for the clinicians involved. The aim of this study was to investigate whether it was possible to identify any subgroup of patients that could potentially be seen in a Voice therapist-led new patient clinic by reviewing the outcome of 96 patients referred to a Joint Voice clinic. Forty-four patients were referred for voice therapy out of which 13 (30%) were teachers or lecturers (total number: 16 (81%)). Two others in this subgroup required medical treatment and the other surgery. The most common aetiology in these professional voice users was muscle tension dysphonia (10 patients, 63%). It is concluded that experienced Voice therapists appropriately trained in laryngostroboscopic assessment could potentially receive and manage direct referrals from primary care physicians. They should however work as part of a multi-professional Voice Disorders Team where the patients could be reviewed by an ENT surgeon if necessary. This would significantly improve the patient pathway for these patients, be cost-effective and make the best use of therapist's and ENT surgeon's time.

  11. Student-Led Objective Tutorial (SLOT) in Medical Education.

    Science.gov (United States)

    Sivagnanam, Gurusamy; Saraswathi, Simansalam; Rajasekaran, Aiyalu

    2006-12-01

    Purpose - To assess an innovative tutoring program named 'Student-Led Objective Tutorial' (SLOT) among undergraduate medical students. Method - The program was conceptualized by the Pharmacology Unit of Faculty of Medicine and Health Sciences, Asian Institute of Medicine Science & Technology (AIMST), Malaysia and implemented in the middle of 2005. A cohort of 246 medical undergraduate students (spread across 5 consecutive batches) participated. Following a brief explanation on the purpose and nature of SLOT, each batch was divided into small groups and was given a reading assignment on 4 previously delivered lecture topics. Each group was asked to prepare 3-5 multiple choice questions (MCQs) of their own in PowerPoint format to be presented, in turns, to the whole class on the day of SLOT. The proceedings were facilitated by 2 lecturers. Student feedback on the efficacy and benefits were assessed through an anonymous self administered questionnaire. Results - About 76% (188) of the students favored SLOT. The acceptance rate of SLOT was higher among males. There was no significant difference between batches in their opinions on whether to pursue SLOT in future. The most prevalent positive comment was that SLOT enhanced learning skills, and the negative comment being, it consumed more time. Conclusions - SLOT is a novel tutorial method which can offset faculty shortage with advantages like enhanced interest among teachers and learners, uniform reach of content, opportunities for group learning, and involvement of visual aids as teaching-learning (T-L) method. SLOT unraveled the students' potential of peer tutoring both inside as well as outside the classroom. Consumer tutors (students) can be tapped as a resource for SLOT for all subjects and courses in healthcare teaching.

  12. Hyperspectral fluorescence imaging with multi wavelength LED excitation

    Science.gov (United States)

    Luthman, A. Siri; Dumitru, Sebastian; Quirós-Gonzalez, Isabel; Bohndiek, Sarah E.

    2016-04-01

    Hyperspectral imaging (HSI) can combine morphological and molecular information, yielding potential for real-time and high throughput multiplexed fluorescent contrast agent imaging. Multiplexed readout from targets, such as cell surface receptors overexpressed in cancer cells, could improve both sensitivity and specificity of tumor identification. There remains, however, a need for compact and cost effective implementations of the technology. We have implemented a low-cost wide-field multiplexed fluorescence imaging system, which combines LED excitation at 590, 655 and 740 nm with a compact commercial solid state HSI system operating in the range 600 - 1000 nm. A key challenge for using reflectance-based HSI is the separation of contrast agent fluorescence from the reflectance of the excitation light. Here, we illustrate how it is possible to address this challenge in software, using two offline reflectance removal methods, prior to least-squares spectral unmixing. We made a quantitative comparison of the methods using data acquired from dilutions of contrast agents prepared in well-plates. We then established the capability of our HSI system for non-invasive in vivo fluorescence imaging in small animals using the optimal reflectance removal method. The HSI presented here enables quantitative unmixing of at least four fluorescent contrast agents (Alexa Fluor 610, 647, 700 and 750) simultaneously in living mice. A successful unmixing of the four fluorescent contrast agents was possible both using the pure contrast agents and with mixtures. The system could in principle also be applied to imaging of ex vivo tissue or intraoperative imaging in a clinical setting. These data suggest a promising approach for developing clinical applications of HSI based on multiplexed fluorescence contrast agent imaging.

  13. Chemical Mahjong

    Science.gov (United States)

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

    An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric…

  14. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil biodeg

  15. Modulation bandwidth enhancement of white-LED-based visible light communications using electrical equalizations

    Science.gov (United States)

    Kwon, D. H.; Yang, S. H.; Han, S. K.

    2015-01-01

    Utilizing the modulation capability of LEDs, there have been many studies about convergence technology to combine illumination and communication. The visible light communication (VLC) system has several advantages such as high security, immunity to RF interference and lower additional cost than comparing to LEDs just for illumination. However, modulation bandwidth of LEDs is not enough for various wireless communication systems. Since the commercial LEDs are designed only for lighting systems; we need an effort to enhance the modulation characteristics of LEDs. When the area of LED is increased, internal junction capacitance of LED is also increased depending on the area of LEDs and then the RC delay time of LED is increased. As a result, the modulation bandwidth of LEDs is limited by large RC delay time. In addition, frequency response of commercial white LED is degraded by the slow response time of the used yellow phosphor. Thus, modulation bandwidth of VLC system is limited to several MHz which is not enough to accommodate high data rate transmission. In this paper, we designed equalization circuit using RLC component for compensating the white LEDs frequency response. Also, we used blue filtering to improve frequency response of white LEDs, which is degraded by yellow phosphorescent component. Power loss by optical filtering and distance is compensated by convex lens. Consequently, we extend the modulation bandwidth of VLC system from 3 MHz to more than 180 MHz, and it allows NRZ-OOK data transmission up to 400 Mbps at 50 cm.

  16. 78 FR 5207 - Certain Led Photographic Lighting Devices and Components Thereof; Commission's Final...

    Science.gov (United States)

    2013-01-24

    ... Film and TV Equipment Factory of Tianjin, China (``Tianjin''); and Stellar Lighting Systems (``Stellar... COMMISSION Certain Led Photographic Lighting Devices and Components Thereof; Commission's Final Determination... general exclusion order prohibiting importation of infringing LED photographic lighting devices...

  17. Integrated LED/Imaging Illumination Panels Demonstrated within a Small Plant Growth Chamber Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LED light sources are ideal for plant growth systems. However, commercially available multi-color LED illumination panels are designed and manufactured to produce a...

  18. Circadian homeostatis of liver metabolism suppresses hepatocarcinogenesis

    Science.gov (United States)

    Chronic jet lag induces spontaneous hepatocellular carcinoma (HCC) in wild-type mice following a mechanism very similar to that observed in obese humans. The process initiates with non-alcoholic fatty liver disease (NAFLD) that progresses to steatohepatitis and fibrosis before HCC detection. This pa...

  19. Role of Methionine Adenosyltransferase Genes in Hepatocarcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Ramani, Komal [Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Southern California Research Center for Alcoholic Liver and Pancreatic Diseases & Cirrhosis, Keck School of Medicine USC, Los Angeles, California 90033 (United States); Mato, José M. [CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology, Park of Bizkaia, 48160 Derio, Bizkaia (Spain); Lu, Shelly C., E-mail: shellylu@usc.edu [Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Southern California Research Center for Alcoholic Liver and Pancreatic Diseases & Cirrhosis, Keck School of Medicine USC, Los Angeles, California 90033 (United States)

    2011-03-24

    Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. Detection of HCC can be difficult, as most of the patients who develop this tumor have no symptoms other than those related to their longstanding liver disease. There is an urgent need to understand the molecular mechanisms that are responsible for the development of this disease so that appropriate therapies can be designed. Methionine adenosyltransferase (MAT) is an essential enzyme required for the biosynthesis of S-adenosylmethionine (AdoMet), an important methyl donor in the cell. Alterations in the expression of MAT genes and a decline in AdoMet biosynthesis are known to be associated with liver injury, cirrhosis and HCC. This review focuses on the role of MAT genes in HCC development and the scope for therapeutic strategies using these genes.

  20. Characteristics of High-Efficient InGaN-Based White LED Lighting

    Science.gov (United States)

    2000-07-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO 11311 TITLE: Characteristics of High-Efficient InGaN -Based White LED ...thru ADP011332 UNCLASSIFIED Characteristics of high-efficient InGaN -based white LED lighting Yuji Uchida’, Tatsumi Setomoto’, Tsunemasa Taguchi...characteristics of an efficient white LEDs lighting source, which is composed of cannon-ball type 10 cd-class InGaN -based white LEDs , are described. It is

  1. Research on measurement of total luminous flux of single LED in direct comparison method

    Science.gov (United States)

    Huang, Biyong; Lai, Lei; Yin, Dejin; Cheng, Weihai; Lin, Fangsheng

    2016-09-01

    This paper focuses on traceability work on total luminous flux of single LED based on the direct camparison method applied for quantity transfer of incandescent lamps. During the test different color groups of LEDs have been chosen as standard to measure total luminous flux of sample LEDs. The test is accomplished in the current integrating sphere measurement system under specific conditions according to LED characteristics. As results obtained from the experiment, the uncertainties are also evaluated.

  2. LED rear combination lamps: styling, robustness, life, packaging, installation, and opportunities for intelligent signal lighting

    Science.gov (United States)

    Eberle, Stefan; Livschitz, Leonard; Raggio, Jeffrey

    2005-02-01

    The automotive industry is rapidly increasing the adoption of LED technology in all vehicle lighting applications. In the near future, LED solutions are expected to capture significant market share for exterior signal lighting. This paper will investigate why LED signal lighting is important to automotive OEMs and consumers, and will exhibit how the latest product development from Lumileds Lighting can enable the ultimate RCL application: a single LED instead of a conventional light bulb.

  3. Advanced Cardiac Resuscitation Evaluation (ACRE: A randomised single-blind controlled trial of peer-led vs. expert-led advanced resuscitation training

    Directory of Open Access Journals (Sweden)

    Hughes Thomas C

    2010-01-01

    Full Text Available Abstract Background Advanced resuscitation skills training is an important and enjoyable part of medical training, but requires small group instruction to ensure active participation of all students. Increases in student numbers have made this increasingly difficult to achieve. Methods A single-blind randomised controlled trial of peer-led vs. expert-led resuscitation training was performed using a group of sixth-year medical students as peer instructors. The expert instructors were a senior and a middle grade doctor, and a nurse who is an Advanced Life Support (ALS Instructor. A power calculation showed that the trial would have a greater than 90% chance of rejecting the null hypothesis (that expert-led groups performed 20% better than peer-led groups if that were the true situation. Secondary outcome measures were the proportion of High Pass grades in each groups and safety incidents. The peer instructors designed and delivered their own course material. To ensure safety, the peer-led groups used modified defibrillators that could deliver only low-energy shocks. Blinded assessment was conducted using an Objective Structured Clinical Examination (OSCE. The checklist items were based on International Liaison Committee on Resuscitation (ILCOR guidelines using Ebel standard-setting methods that emphasised patient and staff safety and clinical effectiveness. The results were analysed using Exact methods, chi-squared and t-test. Results A total of 132 students were randomised: 58 into the expert-led group, 74 into the peer-led group. 57/58 (98% of students from the expert-led group achieved a Pass compared to 72/74 (97% from the peer-led group: Exact statistics confirmed that it was very unlikely (p = 0.0001 that the expert-led group was 20% better than the peer-led group. There were no safety incidents, and High Pass grades were achieved by 64 (49% of students: 33/58 (57% from the expert-led group, 31/74 (42% from the peer-led group. Exact

  4. Developing a new supplemental lighting device with ultra-bright white LED for vegetables

    Science.gov (United States)

    Hu, Yongguang; Li, Pingping; Jiang, Jianghai

    2007-02-01

    It has been proved that monochromatic or compound light-emitting diode (LED) or laser diode (LD) can promote the photosynthesis of horticultural crops, but the promotion of polychromatic light like white LED is unclear. A new type of ultra-bright white LED (LUW56843, InGaN, \

  5. Fabrication of LEDs based on III-V nitrides and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, N. [Optoelectronics Technical Division, Toyoda Gosei Co., Ltd., 710 Origuchi, Shimomiyake heiwa-cho, Nakashima-gun, Aichi 490-1312 (Japan)

    2002-08-16

    III-V nitride semiconductors are useful for LEDs with colors ranging from ultraviolet, blue to green. The luminescence of these LEDs shows a high luminosity and a high purity of color, and, therefore, many applications have been realized using these LEDs. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  6. Fabrication and property analysis of AIGalnP red light LED with high bright

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The LED with DBR and enhancing transmission film was grown by MOCVD. At 20 mA DC injection current, the LED peak wavelength was 623 nm, the light intensity was 200 mcd, and the output light power was 2.14 mW. The light intensity and output light power have been improved than traditional LED.

  7. Integrated Automotive High-Power LED-Lighting Systems in 3D-MID Technology

    NARCIS (Netherlands)

    Thomas, W.

    2014-01-01

    The growing energy consumption of lighting as well as rising luminous efficacies and -fluxes of high-power Light Emitting Diodes (LEDs) have contributed to the widespread use of LEDs in modern lighting systems. One of the most prominent users of the LED-technology is automotive (exterior) lighting.

  8. Bonding bare die LEDs on PET foils for lighting applications: Thermal design modeling and bonding experiments

    NARCIS (Netherlands)

    Ende, D.A. van den; Kusters, R.H.L.; Cauwe, M.; Waal, A. van der; Brand, J. van den

    2012-01-01

    Integration of LEDs on flexible foil substrates is of interest for flexible lighting applications and flexible photonic devices. A matrix of LEDs on a foil combined with a diffuser can be a potential alternative for flexible OLED lighting devices. Preferably, these LEDs are integrated in an unpackag

  9. Large area flexible lighting foils using distributed bare LED dies on polyester substrates

    NARCIS (Netherlands)

    Ende, D.A. van den; Kusters, R.H.L.; Cauwe, M.; Waal, A. van der; Brand, J. van den

    2013-01-01

    Integration of LEDs on flexible foil substrates is of interest for flexible lighting applications and for backlights for flexible displays. Such a large area lighting device can be made by integrating a matrix of closely spaced LEDs on a flexible foil substrate. Preferably, these LEDs are integrated

  10. Color Degradation of Textiles with Natural Dyes and of Blue Scale Standards Exposed to White LED Lamps:Evaluation of White LED Lamps for Effectiveness as Museum Lighting

    Science.gov (United States)

    Ishii, Mie; Moriyama, Takayoshi; Toda, Masahiro; Kohmoto, Kohtaro; Saito, Masako

    White light-emitting diodes (LED) are well suited for museum lighting because they emit neither UV nor IR radiation, which damage artifacts. The color degradation of natural dyes and blue scale standards (JIS L 0841) by white LED lamps are examined, and the performance of white LED lamps for museum lighting is evaluated. Blue scale standard grades 1-6 and silk fabrics dyed with 22 types of natural dyes classified as mid to highly responsive in a CIE technical report (CIE157:2004) were exposed to five types of white LED lamps using different luminescence methods and color temperatures. Color changes were measured at each 15000 lx·hr (500 lx at fabric surface × 300 hr) interval ten times. The accumulated exposure totaled 150000 lx·hr. The data on conventional white LED lamps and previously reported white fluorescent (W) and museum fluorescent (NU) lamps was evaluated. All the white LED lamps showed lower fading rates compared with a W lamp on a blue scale grade 1. The fading rate of natural dyes in total was the same between an NU lamp (3000 K) and a white LED lamp (2869 K). However, yellow natural dyes showed higher fading rates with the white LED lamp. This tendency is due to the high power characteristic of the LED lamp around 400-500 nm, which possibly contributes to the photo-fading action on the dyes. The most faded yellow dyes were Ukon (Curcuma longa L.) and Kihada (Phellodendron amurense Rupr.), and these are frequently used in historic artifacts such as kimono, wood-block prints, and scrolls. From a conservation point of view, we need to continue research on white LED lamps for use in museum lighting.

  11. Treatment of crystallized-fruit wastewater by UV-A LED photo-Fenton and coagulation-flocculation.

    Science.gov (United States)

    Rodríguez-Chueca, Jorge; Amor, Carlos; Fernandes, José R; Tavares, Pedro B; Lucas, Marco S; Peres, José A

    2016-02-01

    This work reports the treatment of crystallized-fruit effluents, characterized by a very low biodegradability (BOD5/COD UV-A LED photo-Fenton process. Firstly, a Box-Behnken design of Response Surface Methodology was applied to achieve the optimal conditions for the UV-A LED photo-Fenton process, trying to maximize the efficiency by saving chemicals and time. Under the optimal conditions ([H2O2] = 5459 mg/L; [Fe(3+)] = 286 mg/L; time >180 min), a COD removal of 45, 64 and 74% was achieved after 360 min, using an irradiance of 23, 70 and 85 W/m(2) respectively. Then a combination of UV-A LED photo-Fenton with coagulation-flocculation-decantation attained a higher COD removal (80%), as well as almost total removal of turbidity (99%) and total suspended solids (95%). Subsequent biodegradability of treated effluents increased, allowing the application of a biological treatment step after the photochemical/CFD with 85 W/m(2).

  12. Development of a broadband cavity enhanced UV-LED spectrometer for the detection of atmospheric HONO and NO2

    Science.gov (United States)

    Wu, Tao; Xia, Ruxiao; Chen, Weidong; He, Xingdao

    2016-10-01

    An incoherent broadband cavity enhanced UV-LED spectrometer (IBBCEAS) was developed to detect atmospheric HONO and NO2. Using a UV light emitting diode (LED) operating at 366 nm in combination with a high finesse optical cavity, HONO and NO2 were able to be simultaneously measured with high sensitivity. Detection limits (for SNR=1) of 0.3 ppbv for HONO and 1 ppbv for NO2 were achieved with an optimum acquisition time of 120 s. Stability of the developed cavity enhanced UV-LED spectrometer has been characterized by means of an Allan variance analysis. Daytime and nighttime concentrations of atmospheric HONO and NO2 were measured and compared with data from LOPAP for HONO and blue light converter-based NOx analyzer for NO2. The present work performed in a real atmospheric environment demonstrates the feasibility of using IBBCEAS technique for interference (chemical and spectral) free measurement of HONO. Experimental detail will be presented, the problems encountered during the real atmospheric measurement will be discussed.

  13. Data banks of chemical substances and their toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Craig, D.K.

    1992-12-31

    Rapid proliferation in the development of new chemical compounds, coupled with the discovery and/or identification of those already in existence, has led to a significant need to investigate their physicochemical and biological properties, to document the knowledge gained, and to communicate that knowledge in as convenient a manner as possible. This paper presents and briefly discusses several prominent chemical databases.

  14. Data banks of chemical substances and their toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Craig, D.K.

    1992-01-01

    Rapid proliferation in the development of new chemical compounds, coupled with the discovery and/or identification of those already in existence, has led to a significant need to investigate their physicochemical and biological properties, to document the knowledge gained, and to communicate that knowledge in as convenient a manner as possible. This paper presents and briefly discusses several prominent chemical databases.

  15. Composition dependence of luminescence of Eu and Eu/Tb doped silicate glasses for LED applications

    DEFF Research Database (Denmark)

    Zhu, C.F.; Chaussedent, S.; Liu, S.

    2013-01-01

    The Eu and Eu/Tb doped silicate glasses are good candidates for light emitting diode (LED) applications. But the optical performance of these glasses is sensitive to variations in chemical composition. In this paper we report our recent findings about the effect of addition of minor components....... The results show that the asymmetry factor and luminescence lifetimes of as-prepared materials are dependent on composition. White fluorescence is achieved in Eu/Tb co-doped glasses, which can be attributed to the simultaneous generation of red, green and blue wavelengths from Eu3+ and Tb3+ ions...... such as B2O3, Al2O3 and CaF2 on the luminescent properties of the above-mentioned glasses. We explore the role of Eu3+ ions as a structural probe of the glasses by determining the asymmetry factor, i.e., the ratio of the emission intensity of the 5D0→7F2 transition to that of the 5D0 →7F1 transition...

  16. Evaluation of cotton-fabric bleaching using hydrogen peroxide and Blue LED

    Science.gov (United States)

    de Oliveira, Bruno P.; Moriyama, Lilian T.; Bagnato, Vanderlei S.

    2015-06-01

    The raw cotton production requires multiple steps being one of them the removal of impurities acquired during previous processes. This procedure is widely used by textile industries around the world and is called bleaching. The raw cotton is composed by cellulosic and non-cellulosic materials like waxes, pectins and oils, which are responsible for its characteristic yellowish color. The bleaching process aims to remove the non-cellulosic materials concentration in the fabric, increasing its whiteness degree. The most used bleaching method utilizes a bath in an alkali solution of hydrogen peroxide, stabilizers and buffer solutions under high temperature. In the present study we evaluated the possibility of using a blue illumination for the bleaching process. We used blue LEDs (450 nm) to illuminate an acid hydrogen peroxide solution at room temperature. The samples treated by this method were compared with the conventional bleaching process through a colorimetric analysis and by a multiple comparison visual inspection by volunteers. The samples were also studied by a tensile test in order to verify the integrity of the cloth after bleaching. The results of fabric visual inspection and colorimetric analysis showed a small advantage for the sample treated by the standard method. The tensile test showed an increasing on the yield strength of the cloth after blue light bleaching. The presented method has great applicability potential due to the similar results compared to the standard method, with relative low cost and reduced production of chemical waste.

  17. Color Temperature Tunable White-Light LED Cluster with Extrahigh Color Rendering Index

    OpenAIRE

    Minhao Zhang; Yu Chen; Guoxing He

    2014-01-01

    The correlated color temperature (CCT) tunable white-light LED cluster with extrahigh color rendering property has been found by simulation and fabricated, which consists of three WW LEDs (CCT = 3183 K), one red LED (634.1 nm), one green LED (513.9 nm), and one blue LED (456.2 nm). The experimental results show that this cluster can realize the CCT tunable white-lights with a color rendering index (CRI) above 93, special CRI R9 for strong red above 90, average value of the special CRIs of R9...

  18. Computer Modeling and Simulation Evaluation of High Power LED Sources for Secondary Optical Design

    Institute of Scientific and Technical Information of China (English)

    SU Hong-dong; WANG Ya-jun; DONG Ji-yang; CHEN Zhong

    2007-01-01

    Proposed and demonstrated is a novel computer modeling method for high power light emitting diodes(LEDs). It contains geometrical structure and optical property of high power LED as well as LED dies definition with its spatial and angular distribution. Merits and non-merits of traditional modeling methods when applied to high power LEDs based on secondary optical design are discussed. Two commercial high power LEDs are simulated using the proposed computer modeling method. Correlation coefficient is proposed to compare and analyze the simulation results and manufacturing specifications. The source model is precisely demonstrated by obtaining above 99% in correlation coefficient with different surface incident angle intervals.

  19. Multichip on Aluminum Metal Plate Technology for High Power LED Packaging

    Institute of Scientific and Technical Information of China (English)

    Choong-mo NAM; Mi-hee JI

    2010-01-01

    Multichip on Aluminum Metal Plate(MOAMP) technology with simple structure and low thermal resistance is developed for effective heat removal of Light Emitting Diode(LED) p-n junction and LED lighting module to have high reliability. The thermal resistance of LED modules was numerical and experimental. Thermal resistance from the junction to aluminum metal plate, considering input power of LED module using MOAMP technology, is 3.02 K/W, 3.23 K/W for the measured and calculated, respectively. We expect that the reported MOAMP technology with low thermal resistance will be a promising solution for high power LED lighting modules.

  20. Comparison of the copper and gold wire bonding processes for LED packaging*

    Institute of Scientific and Technical Information of China (English)

    Chen Zhaohui; Liu Yong; Liu Sheng

    2011-01-01

    Wire bonding is one of the main processes of the LED packaging which provides electrical interconnection between the LED chip and lead frame The gold wire bonding process has been widely used in LED packaging industry currently. However, due to the high cost of gold wire, copper wire bonding is a good substitute for the gold wire bonding which can lead to significant cost saving. In this paper, the copper and gold wire bonding processes on the high power LED chip are compared and analyzed with finite element simulation. This modeling work may provide guidelines for the parameter optimization of coppor wire bonding process on the high power LED packaging.

  1. LED背光源前景看好%There's an LED Backlight in Your Future

    Institute of Scientific and Technical Information of China (English)

    Steve Sechrist

    2006-01-01

    @@ LED backlight solution provider Global Lighting Technologies (GLT) (Brecksville, OH) is going to introduce a new family of LED light guides with plans to demonstrate a 24"(61 cm) LCD-TV with an LED backlight.To understand the significance of this announcement, we have to go back to a presentation given last month at the Strategies in Light (SIL) Conference held in San Francisco. There, Seoul Semiconductor VP, Dr. Jae Jo Kim, listed low efficiency (high cost) as the number one obstacle to large LCD adoption of LED lighting particularly, the number of LEDs required to adequately replace today's cold-cathode fluorescent lamps (CCFLs).

  2. On the applicability of the principle of the quantity-to-quality transition to chemical evolution that led to life

    Science.gov (United States)

    Kolb, Vera M.

    2005-10-01

    We review and re-examine the arguments for the proposal that life emerged by a quantity-to-quality transition of abiotic matter. This idea was originally proposed by the dialectical materialists, who are the proponents of the materialistic approach to Hegel's laws of dialectics. We find that one of the universal features of the quantity-to-quality transitions is the change in the organization of the system, which brings about novelty. We suggest that the principle of the quantity-to-quality transition may be a part of the algorithm of life, which is not Earth-centric.

  3. Optical design and lighting application of an LED-based sports lighting system

    Science.gov (United States)

    Boxler, Larry

    2011-10-01

    This paper describes both the optical development of an LED-based sports lighting system and the results of the application of the system to an actual sport field. A traditional sport lighting fixture is generally composed of a single 1500 watt High Intensity Discharge (HID) light source with reflectors used to control the light distribution. The efficacy of the HID light source is equivalent or nearly equivalent to most LED light sources, putting LEDs at a large cost disadvantage in a high light output application such as sports lighting due to the number of LEDs and supporting components required to run an LED system. To assess the feasibility and applicability of LEDs in a sports lighting application, an LED-based sport light has been developed and installed on a small soccer field specified to have an average maintained illuminance level of 30 footcandles. An existing HID sport lighting system was also installed on the same size soccer field adjacent to the LED field with the same average footcandle level for comparison. Results indicate that LEDs can provide equivalent average illumination; however the LED source and system component cost is substantially higher. Despite the high cost, it was found that improved optical control afforded by the optical design used in the system provides a significant improvement in offsite wasted spill light, glare control, and on field uniformity. This could provide an advantage for LED systems.

  4. Chemical cosmology

    CERN Document Server

    Boeyens, Jan CA

    2010-01-01

    The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp

  5. LED 扩散板光扩散的性能评价的研究%Study on the Light Diffusion Performance Evaluation of LED Diffusion Plate

    Institute of Scientific and Technical Information of China (English)

    彭文利

    2013-01-01

      LED 扩散板光扩散的性能评价是根据环境要求和不同场所照度标准要求,利用 LED 扩散板光扩散的性能(如照度均匀度、眩光限制、光源颜色、显色性、反射比等),生产出具备一定柔和舒适度的 LED 照明灯具,制造出符合室内照明要求的气氛照明、情景照明、情调照明,满足用户的各种照明要求,其造型也要符合用户的审美观,最主要的是符合能源高效的利用。这项技术的成功研制将会使我国 LED 灯具在 LED 国际市场的竞争中处于优势地位,打开国际市场。这项技术的成功研制也填补了行业内无 LED 扩散板光扩散的性能评价体系的一个空白。%The light diffusion performance evaluation of LED diffusion plate is based on the environmental requirements and standards requirements in different places. The use of the light diffusion properties (e.g., uniformity of illumination, glare limitation, the light source color, the color, reflectance, etc.) of LED diffusion plate can product the LED light with soft comfort. It can create the mood lighting, scene lighting and mood lighting meeting the indoor lighting requirements and the user's requirements, and its shape is also in line with the aesthetics of the user, the most important is compliance with the energy efficient use. The success of this technology will make China's LED lamps in a dominant position in the LED international market competition, and open the international market. And it also will fill a blank of the light diffusion performance evaluation system of LED diffuser plate.

  6. Increase of energy efficiency in horticultural tissue culture with high-power-LED lighting systems; Energieeffizienzsteigerung pflanzlicher In-vitro-Kulturverfahren mit Hochleistungs-LED-Belichtungssystemen

    Energy Technology Data Exchange (ETDEWEB)

    Bornwasser, Thorsten

    2011-07-01

    The lighting of tissue cultures is one of the main cost factors in growing rooms due to the high energy need. A lighting system with high-power light-emitting diodes (HP-LEDs) was tested as an alternative to the conventionally used fluorescent tubes. Therefore the HP-LED-types royal-blue, red, and cool white were used to create different spectral outputs. The photon flux yield, level of efficiency, and spectral shift of the single HP-LEDs were measured beforehand at different operating conditions (i.e. increasing current and junction temperature). The energy efficiency of the HP-LED lighting system was determined at 0.83 {mu}mol W{sup -1}s{sup -1} with the same shelf board distance (300 mm) and average PPFD on the exposed surface as compared to the control lighting system. The energy efficiency of the fluorescent lighting system could reach a maximum value of 0.68 {mu}mol W{sup -1}s{sup -1}. In addition to the reduced energy needs, HP-LED lighting systems reduce the need for cooling energy in culture rooms to regulate the room temperature. HP-LED lighting systems allow the reduction of the shelf board distance due to the small mass volume of LEDs and diminished radiant heat output towards the plant. The lower shelf board distance led to an additional increase of the energy efficiency up to 1.16 {mu}mol W{sup -1}s{sup -1} at a distance of 210 mm. Simultaneously the PPFD distribution was more regular than under the exposure with a fluorescent tube. Beside the increase of energy efficiency, HP-LEDs facilitate the control of the spectral composition. The spectral output can be adjusted to the plants' needs and thereby permit a more optimal production and influence the plant morphology (Nhut und Na, 2010; Morrow, 2008). Various plant tissue cultures and their response to different spectral compositions were investigated with the developed HP-LED lighting system. For none of the tested cultures could a preference for one of the spectral compositions be determined

  7. An efficient luminescence conversion LED for white light emission, fabricated using a commercial InGaN LED and a 1,8-naphthalimide derivative

    Science.gov (United States)

    Kim, Hyun-Jeong; Jin, Ji-Young; Lee, Youn-Sik; Lee, Sang-Hee; Hong, Chang-Hee

    2006-11-01

    A highly efficient luminescence conversion light emitting diode (LUCO LED) was fabricated, using a commercial InGaN LED (460 nm) and 4- N, N-diphenyl-9-(4- tert-butylphenyl)-1,8-naphthalimide (DBN), dispersed in epoxy as the primary light source and LUCO material, respectively. The emission of very bright white light was observed at 20 mA, with CIE chromaticity coordinates of (0.32, 0.33) and conversion efficiency of 82%. The luminescent output of the LUCO LED decreased rapidly, but when the LUCO LED was prepared using DNB dispersed in poly(methyl methacrylate), it only decreased to about 67% of the initial value after 19 days of continual operation at 200 mA.

  8. Comparison between the behavior of dosimeters FAM and FAT after irradiation with LED; Comparacao entre o comportamento dos dosimetros FAM e FAT apos irradiacao com LED

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, M.G.O.; Lima, V.L.; Nascimento, R.K.; Souza, V.L.B., E-mail: vlsouza@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil). Divisao de Laboratorios Tecnico-Cientifico

    2013-08-15

    The work consists in evaluating the photosensitivity of Fricke solution modified by addition of dyes acting as a photosensitizers, comparing the behavior of FAM dosimeters (Fricke solution modified by addition of methylene blue) and FAT (Fricke solution modified by addition of toluidine blue) after irradiation with LED in acrylic phantom. An arrangement of LED, prepared for this purpose and a set of commercially available LED were used for irradiation the samples, as well as an acrylic phantom. The results show that the FAM is more sensitive dosimeter than FAT; samples irradiated with LED demonstrated the sensitivity of the dosimeters to red and blue light obtaining calibration curves with good correlation coefficients, so that these dosimeters may be used in the future for photodynamic therapy dosimetry. (author)

  9. Setup of a LED light-pulser system for the OLYMPUS experiment; Aufbau eines LED-Lichtpulsersystems fuer das OLYMPUS-Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Waqaas

    2011-12-15

    The aim of this thesis consists in the construction and test of an external light-calibration system based on light-emitting diodes (LED) for the application at the symmetric Moller/Bhabha (SYMB) luminosity monitor. In chapter 2 the theoretical foundations of the OLYMPUS experiment, especially of the SYMB luminosity monitor are explained. Thereafter in chapter 3 the details of the setup of the OLYMPUS experiment and the fundamental properties of the SYMB detectors are discussed. In chapter 4 the whole concept of the LED light-pulser system is treated. In chapter 5 then test measurements with the ready LED light-pulser system are described. Thereby the light source shall be optimized in the shape that thereafter light pulses with short signal width are producable. Also different measurements for the unique characterization of the systems are performed. In chapter 6 light-intensity measurements during the operation of the LED light-pulser system are described.

  10. Design of crossed-mirror array to form floating 3D LED signs

    Science.gov (United States)

    Yamamoto, Hirotsugu; Bando, Hiroki; Kujime, Ryousuke; Suyama, Shiro

    2012-03-01

    3D representation of digital signage improves its significance and rapid notification of important points. Our goal is to realize floating 3D LED signs. The problem is there is no sufficient device to form floating 3D images from LEDs. LED lamp size is around 1 cm including wiring and substrates. Such large pitch increases display size and sometimes spoils image quality. The purpose of this paper is to develop optical device to meet the three requirements and to demonstrate floating 3D arrays of LEDs. We analytically investigate image formation by a crossed mirror structure with aerial aperture, called CMA (crossed-mirror array). CMA contains dihedral corner reflectors at each aperture. After double reflection, light rays emitted from an LED will converge into the corresponding image point. We have fabricated CMA for 3D array of LEDs. One CMA unit contains 20 x 20 apertures that are located diagonally. Floating image of LEDs was formed in wide range of incident angle. The image size of focused beam agreed to the apparent aperture size. When LEDs were located three-dimensionally (LEDs in three depths), the focused distances were the same as the distance between the real LED and the CMA.

  11. Straightforward fabrication of stable white LEDs by embedding of inorganic UV-LEDs into bulk polymerized polymethyl-methacrylate doped with organic dyes

    OpenAIRE

    Di Martino, Daniela; Beverina, Luca; Sassi, Mauro; Brovelli, Sergio; Tubino, Riccardo; Meinardi, Francesco

    2014-01-01

    Stable white-emitting down-converted LEDs are straightforwardly prepared by bulk polymerization of an organic dye doped polymethyl-methacrylate (PMMA) shell directly on top of a highly efficient commercial blue-emitting InGaN LED. Our optimized polymerization procedure allows for extending the form factor of achievable luminescence converter (LUCO) material beyond the conventional thin film form and to directly produce devices with light bulb design. The selected organic dyes, the blue-emitti...

  12. 大功率 LED 散热结构的优化设计%Optimization Design Based on the Heat Radiation Structure of High -power LED

    Institute of Scientific and Technical Information of China (English)

    马验宗; 张忠山; 智郁雯; 陈鹏宇; 严一民

    2015-01-01

    大功率 LED 与传统光源相比优势明显,应用前景非常广阔。但由于体积小,发热集中,LED 芯片不能承受高温等原因,散热问题成为了制约大功率 LED 发展的主要原因。该文结合三维模型设计软件 Pro /Engineer 5.0和流体传热分析软件FloEFD PRO12.1对5 W 的 LED 的散热模型进行建模和热仿真,运用控制变量的方法来探索散热器翅片厚度、曲率及微结构对散热性能的影响规律,并依据规律对散热器结构进行优化。%Compared to the traditional light source,high -power LED retains decided advantages,along with wide application pros-pects.However,heat dissipation has been the major obstacle to the further development of high power LED because of its small vol-ume,heat concentration,and bad resistance to high temperature of the LED chip.Through combining the 3D model design software Pro /Engineer 5.0 heat transfer and fluid analysis software FloEFD PRO12.1,one achieves the model and thermal simulation of 5 W LED heat cooling model.In addition,by applying the method of controlled variable,the radiator fin thickness,curvature and the effect laws of microstructure on the heat dissipation performance have further been explored,therefore enable the structure of radiator get fur-ther optimized.

  13. Effects of LED or laser phototherapy on bone defects grafted with MTA and irradiated with laser or LED light: a comparative Raman spectroscopic study

    Science.gov (United States)

    Pinheiro, Antonio L. B.; Soares, Luiz G. P.; Barbosa, Artur Felipe S.; Silveira, Landulfo, Jr.

    2012-03-01

    We studied peaks of calcium hydroxyapatite - CHA on defects grafted with MTA, treated or not with Light Emitting Diode - LED or IR Laser. 54 rats were divided in 6 groups each subdivided into 3 subgroups (15,21,30d). LED (λ850 +/- 10nm) or IR Laser (λ850 nm) was applied over (LED) or in 4 points around the defect at 48 h intervals for 15 days. Raman readings were taken at the surface of the defect. The smaller overall intensity of the peak was found in Group MTA + Laser (1510.2 +/- 274.1) and the highest on Group LED (2322 +/- 715). There were no statistically significant differences between non-irradiated subjects on regards the CHA peaks. On the other hand, there were statistically significant differences between the Group Clot and LED, Clot and Laser, and Clot and MTA + Laser (p =0.01, p = 0.02, p = 0.003). There were no significant differences between Group MTA and MTA + LED (p=0.2) but significant differences were seen between Groups MTA and MTA + Laser (p=0.01). Significant differences were also observed between Groups LED and Laser (p MTA + LED and MTA + Laser (p=0.009). MTA, due to its characteristics, seemed to be directly affected by the light. However, the use of either phototherapy positively affected bone healing similarly as observed on different studies using other biomaterials. The overall analysis of our results indicated that the use of either light source resulted in a better, more advanced, and of quality bone repair.

  14. Chemical Analyses

    Science.gov (United States)

    Bulluck, J. W.; Rushing, R. A.

    1994-01-01

    As a preliminary study on the effects of chemical aging of polymer materials MERL and TRI have examined two polymeric materials that are typically used for offshore umbilical applications. These two materials were Tefzel, a copolymer of ethylene and tetrafluoroethylene, and Coflon, polyvinylidene fluoride. The Coflon specimens were cut from pipe sections and exposed to H2S at various temperatures and pressures. One of these specimens was tested for methane permeation, and another for H2S permeation. The Tefzel specimens were cut from .05 mm sheet stock material and were exposed to methanol at elevated temperature and pressure. One of these specimens was exposed to methanol permeation for 2 days at 100 C and 2500 psi. An additional specimen was exposed to liquid methanol for 3 days at 150 C and 15 Bar. Virgin specimens of each material were similarly prepared and tested.

  15. Construction of Tungsten Halogen, Pulsed LED, and Combined Tungsten Halogen-LED Solar Simulators for Solar Cell I-V Characterization and Electrical Parameters Determination

    Directory of Open Access Journals (Sweden)

    Anon Namin

    2012-01-01

    Full Text Available I-V characterization of solar cells is generally done under natural sunlight or solar simulators operating in either a continuous mode or a pulse mode. Simulators are classified on three features of irradiance, namely, spectral match with respect to air mass 1.5, spatial uniformity, and temporal stability. Commercial solar simulators use Xenon lamps and halogen lamps, whereas LED-based solar simulators are being developed. In this work, we build and test seven simulators for solar cell characterization, namely, one tungsten halogen simulator, four monochromatic (red, green, blue, and white LED simulators, one multicolor LED simulator, and one tungsten halogen-blue LED simulator. The seven simulators provide testing at nonstandard test condition. High irradiance from simulators is obtained by employing elevated supply voltage to tungsten halogen lamps and high pulsing voltages to LEDs. This new approach leads to higher irradiance not previously obtained from tungsten halogen lamps and LEDs. From I-V curves, electrical parameters of solar cell are made and corrected based on methods recommended in the IEC 60891 Standards. Corrected values obtained from non-STC measurements are in good agreement with those obtained from Class AAA solar simulator.

  16. An inducible krasV12 transgenic zebrafish model for liver tumorigenesis and chemical drug screening

    Directory of Open Access Journals (Sweden)

    Anh Tuan Nguyen

    2012-01-01

    Because Ras signaling is frequently activated by major hepatocellular carcinoma etiological factors, a transgenic zebrafish constitutively expressing the krasV12 oncogene in the liver was previously generated by our laboratory. Although this model depicted and uncovered the conservation between zebrafish and human liver tumorigenesis, the low tumor incidence and early mortality limit its use for further studies of tumor progression and inhibition. Here, we employed a mifepristone-inducible transgenic system to achieve inducible krasV12 expression in the liver. The system consisted of two transgenic lines: the liver-driver line had a liver-specific fabp10 promoter to produce the LexPR chimeric transactivator, and the Ras-effector line contained a LexA-binding site to control EGFP-krasV12 expression. In double-transgenic zebrafish (driver-effector embryos and adults, we demonstrated mifepristone-inducible EGFP-krasV12 expression in the liver. Robust and homogeneous liver tumors developed in 100% of double-transgenic fish after 1 month of induction and the tumors progressed from hyperplasia by 1 week post-treatment (wpt to carcinoma by 4 wpt. Strikingly, liver tumorigenesis was found to be ‘addicted’ to Ras signaling for tumor maintenance, because mifepristone withdrawal led to tumor regression via cell death in transgenic fish. We further demonstrated the potential use of the transparent EGFP-krasV12 larvae in inhibitor treatments to suppress Ras-driven liver tumorigenesis by targeting its downstream effectors, including the Raf-MEK-ERK and PI3K-AKT-mTOR pathways. Collectively, this mifepristone-inducible and reversible krasV12 transgenic system offers a novel model for understanding hepatocarcinogenesis and a high-throughput screening platform for anti-cancer drugs.

  17. Enhancement of light extraction efficiency of vertical LED with patterned graphene as current spreading layer

    Science.gov (United States)

    Singh, Sumitra; Sai Nandini, Annam Deepthi; Pal, Suchandan; Dhanavantri, Chenna

    2016-01-01

    In this paper we report an optimised pattern of surface textured graphene current spreading layer (CSL) for the enhancement of light extraction efficiency (LEE) in InGaN/GaN vertical light emitting diodes (V-LEDs). It is found that by texturing graphene surface LEE improves drastically. This improvement is attributed to better current spreading of graphene and increased random and multiple scattering of light through textured surfaces. Simulation results illustrate that V-LEDs with surface textured (hexagonal pattern) ITO as CSL shows threefold improvement in light extraction efficiency compared to V-LEDs with no surface texturing on ITO CSL. Further, LEE of V-LEDs having patterned graphene CSL is compared with that for indium tin oxide (ITO) CSL. V-LEDs with optimised hexagonal patterning on graphene CSL shows 13.42% enhancement of LEE compared to that of LED with hexagonal patterning on ITO surface.

  18. A high-performance stand-alone solar PV power system for LED lighting

    KAUST Repository

    Huang, B. J.

    2010-06-01

    The present study developed a high-performance solar PV power technology for the LED lighting of a solar home system. The nMPPO (near-Maximum-Power- Point- Operation) design is employed in system design to eliminate MPPT. A feedback control system using pulse width modulation (PWM) technique was developed for battery charging control which can increase the charging capacity by 78%. For high-efficiency lighting, the LED is directly driven by battery using a PWM discharge control to eliminate a DC/DC converter. Two solar-powered LED lighting systems (50W and 100W LED) were built. The long-term outdoor tests have shown that the loss of load probability for full-night lighting requirement is zero for 50W LED and 3.6% for 100W LED. © 2010 IEEE.

  19. Fabrication of White LED Using InGaN Blue LED and Ce3+:YVO4 Fluorescence%用Ce3+:YVO4晶体荧光粉与蓝光LED制造自然白光LED

    Institute of Scientific and Technical Information of China (English)

    刘景旺

    2007-01-01

    本文报导了通过结合自行制备的掺铈钒酸钇晶体(Ce3+:YVO4)荧光粉与InGaN/GaN蓝光发光二极管(LED)结合而得的白光发光二极管(W-LED).在室温、正向电压3.5V、正向电流20mA时W-LED的CIE色坐标为(0.32,0.37),接近纯白色(0.33,0.33).

  20. The Fabrication of White LED Using InGaN Blue LED and YAG Fluorescence%用InGaN蓝光LED与YAG荧光粉制造自然白光LED

    Institute of Scientific and Technical Information of China (English)

    王宇方; 杨志坚; 丁晓民; 姚光庆; 段洁菲; 林建华; 张国义

    2002-01-01

    报导了用国内自行研制的InGaN/GaN蓝光发光二极管(LED)与钇铝石榴石(YAG)荧光粉结合而得的白光发光二极管(W-LED).在室温,正向电压3.5V,正向电流20mA时,W-LED轴向亮度为1cd,CIE色坐标为(0.31,0.38),接近纯白色(0.33,0.33).

  1. Powerful nanosecond light sources based on LEDs for astroparticle physics experiments

    OpenAIRE

    Lubsandorzhiev, B. K.; Poleshuk, R. V.; Shaibonov, B. A. J.; Vyatchin, Y. E.

    2007-01-01

    Powerful nanosecond light sources based on LEDs have been developed for use in astroparticle physics experiments. The light sources use either matrixes of ultra bright blue LEDs or a new generation high power blue LEDs. It's shown that such light sources have light yield of up to 10**10 - 10**12 photons per pulse with very fast light emission kinetics. The described light sources are important for use in calibration systems of Cherenkov and scintillator detectors. The developed light sources ...

  2. LED 光源を利用した牡蠣養殖の研究

    OpenAIRE

    2015-01-01

    Situation that inhibit oyster farming by coastal waters of environmental change has occurred. In this study, we observed the effect of LED light source has on the phytoplankton. In order to stabilize the oyster farming, as well as the LED light source to observe a positive effect to be given to the areas where oyster farming is done, aiming to develop a LED lamp oyster.

  3. Evaluation of nurse-led follow up for patients undergoing pelvic radiotherapy

    OpenAIRE

    Faithfull, S; Corner, J.; MEYER L.; Huddart, R; Dearnaley, D.

    2001-01-01

    This study reports results from a randomised controlled trial of nurse-led care and was designed to determine whether nurse-led follow up improved patients morbidity and satisfaction with care in men treated with radical radiotherapy for prostate and bladder cancer. The aim was to compare outcomes in terms of toxicity, symptoms experienced, quality of life, satisfaction with care and health care costs, between those receiving nurse-led care and a group receiving standard care. The study popul...

  4. Characteristics of the autostereoscopic three-dimensional LED display based on diffractive optical elements sheet

    Science.gov (United States)

    Su, Ping; An, Pengli; Ma, Jianshe; An, Shu; Cao, Liangcai

    2016-10-01

    Research on the characteristic of the autostereoscopic LED display (ALEDD) using DOEs sheet is of prime importance to the widely application of the (ALEDD). In this paper, the effects caused by the assembling errors between the LED display and DOEs sheet are theoretically and experimentally analyzed. The results show that, the tolerance assembling errors are | Δ z |autostereoscopic three-dimensional LED display system to reduce the crosstalk and improve the quality of 3D perception.

  5. NIR-LEDs lighting system for enhancing Brix distinction with saving energy to agricultural products

    Science.gov (United States)

    Lee, Kwang-Hoon; Lee, Dong-Kil; Kim, Yang-Gyu; Park, Ahn-Jin; Jang, Won-Geun; Park, Youngsik

    2014-05-01

    In this paper, the sugar content prediction determination system in optical non-contact type based on the near infrared light emitting diode (NIR-LED) lamp is proposed. As the result NIR-LED lamp reduced 86% of the energy consumption compared to the case of Halogen lamp in the same process of sugar content determination. And the result of prediction of sugar content by NIR-LED lamp is shown to as near the same level of Halogen lamp system.

  6. The study of LED lighting standard system%LED 照明标准体系建设现状研究

    Institute of Scientific and Technical Information of China (English)

    贺素霞

    2014-01-01

    In this paper , through the analysis of the LED universal test system in China and the comparison of the standard system of the abroad LED universal test system, the problems of the LED universal test standard system in development were known .The relation of the LED standards of China based on the LED standards that has been formulated was summarized ,the relations and differences were studied about LED lighting standards in different and corporate standards with international standards differences and relations were analyzed , How to be in line with international standards was studied . Constructive ideas for the LED standard system were put forwerd and how to apply to teaching,research and laboratory construction was studied .%文章通过对我国LED灯具标准体系的分析和国内外的LED通用测试体系的建设研究状况的对比,了解我国LED通用测试标准体系发展中的问题,结合LED照明产品特点及我国各部门和地方正在积极制定LED照明标准的实际情况,分析总结研究国内现有LED照明标准之间的联系和关键点,研究我国LED照明国家标准、行业标准、地方标准、企业标准与国际标准的区别与联系,研究如何与国际标准接轨。为LED标准体系建设提出建设性意见并研究如何应用于LED教学、科研和实验室建设。

  7. CALiPER Benchmark Report: Performance of Incandescent A Type and Decorative Lamps and LED Replacements

    Energy Technology Data Exchange (ETDEWEB)

    Lingard, R. D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Myer, M. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Paget, M. L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2008-11-01

    This benchmark report addresses common omnidirectional incandescent lamps - A-type and small decorative, candelabra-type lamps - and their commercially available light-emitting diode (LED) replacements.

  8. High quality GaN-based LED epitaxial layers grown in a homemade MOCVD system

    Institute of Scientific and Technical Information of China (English)

    Yin Haibo; Wang Xiaoliang; Ran Junxue; Hu Guoxin; Zhang Lu; Xiao Hongling; Li Jing; Li Jinmin

    2011-01-01

    A homemade 7 × 2 inch MOCVD system is presented.With this system,high quality GaN epitaxial layers,InGaN/GaN multi-quantum wells and blue LED structural epitaxial layers have been successfully grown.The non-uniformity of undoped GaN epitaxial layers is as low as 2.86%.Using the LED structural epitaxial layers,blue LED chips with area of 350 × 350μm2 were fabricated.Under 20 mA injection current,the optical output power of the blue LED is 8.62 mW.

  9. New Design of a Low Cost Analogue Current Supply for Power LEDs

    Directory of Open Access Journals (Sweden)

    Radu Bogdan Dragomir

    2013-04-01

    Full Text Available The present paper proposes an innovative and inductive ballast-based power LED supply. This new design LED powering solution is a cost-efficient alternative to high-end switching mode power supply (SMPS used to feed LED clusters. The current supply circuit topology will be explained. The AC component of the LED current is analysed both from the ballast inductance and the value of the DC filtering capacitor standpoint. The PSIM and MATLAB tools have been used to simulate the circuit output when different ballast voltage conditions will be applied. Transitory and steady-state driver performances have been taken into account.

  10. Brightness increase using dual parabolic recycling collar and RGBW LEDs for pico-projector applications

    Science.gov (United States)

    Li, Kenneth

    2014-02-01

    Spherical reflector had been used to recycle light in LEDs so as to increase the brightness of the system. The LED is placed at the center of curvature of the spherical reflector and the emitted light is reflected back to the LED itself by the spherical reflector. For single color LED place at the center, this system will suffice. But for multiple LEDs of different colors, due to imaging property of the spherical reflector, the image of a chip is imaged diagonally to the opposite side of the center of curvature, and not onto itself. As a result, recycling can only occur on symmetrically placed LEDs with different colors. A parabolic reflector system with two reflections is described here such that the output from a LED is reflected back to itself. When it is placed at the proximity of the center of curvature, there will be minimum distortion with higher recycling efficiency. The single reflection from a spherical is analogous to a single lens producing inverted images. The two reflections from this parabolic reflector system is similar to imaging with two lenses where the image become upright. Such system will be very applicable to LED packages with multiple LEDs, for example, RGBW, RGGB, etc. used in entertainment lighting systems.

  11. Smart LED allocation scheme for efficient multiuser visible light communication networks.

    Science.gov (United States)

    Sewaiwar, Atul; Tiwari, Samrat Vikramaditya; Chung, Yeon Ho

    2015-05-18

    In a multiuser bidirectional visible light communication (VLC), a large number of LEDs or an LED array needs to be allocated in an efficient manner to ensure sustainable data rate and link quality. Moreover, in order to support an increasing or decreasing number of users in the network, the LED allocation is required to be performed dynamically. In this paper, a novel smart LED allocation scheme for efficient multiuser VLC networks is presented. The proposed scheme allocates RGB LEDs to multiple users in a dynamic and efficient fashion, while satisfying illumination requirements in an indoor environment. The smart LED array comprised of RGB LEDs is divided into sectors according to the location of the users. The allocated sectors then provide optical power concentration toward the users for efficient and reliable data transmission. An algorithm for the dynamic allocation of the LEDs is also presented. To verify its effective resource allocation feature of the proposed scheme, simulations were performed. It is found that the proposed smart LED allocation scheme provides the effect of optical beamforming toward individual users, thereby increasing the collective power concentration of the optical signals on the desirable users and resulting in significantly increased data rate, while ensuring sufficient illumination in a multiuser VLC environment.

  12. High-power LEDs influence on germination rate of tomato seeds

    Science.gov (United States)

    Tudora, Cătălina; Ristici, M.; Ristici, Esofina

    2007-08-01

    Artificial lighting for plants cultivation is an important factor that can determine the nutritional quality of vegetables. The improvement of quality is determined by the emission spectrum of LED, suitable for vegetables. This spectrum values must be inside the solar ones. So, by using red high-power LEDs we can supplement the conventional lighting (ex. HPS) and we can enrich the red light from the emission light. We have used a special device that has 200 high-power red LEDs, having emission wavelength in 640-670 nm range, which is presented below. Using red LEDs on tomato seeds, we can observe that the germination rate significantly increased.

  13. Analysis of compact and portable goniospectrometer system for test of LED lamps

    DEFF Research Database (Denmark)

    Dam-Hansen, Carsten; Amdemeskel, Mekbib Wubishet; Thorseth, Anders

    2015-01-01

    measurements in a near-field goniophotometer. A collection of six different types of directional and non-directional integrated LED lamps with three samples of each were used as test devices. It is shown that the main uncertainty comes from the inadequate thermal stabilisation of the LED lamps. With pre......-heating relative differences for total luminous flux of ±2,5% were obtained. Reliable photometric data can be obtained for use in market monitoring to identify probable non-compliance LED lamps and hence as an improved method for selecting LED lamps for accredited verification testing....

  14. Development of high-frame-rate LED panel and its applications for stereoscopic 3D display

    Science.gov (United States)

    Yamamoto, H.; Tsutsumi, M.; Yamamoto, R.; Kajimoto, K.; Suyama, S.

    2011-03-01

    In this paper, we report development of a high-frame-rate LED display. Full-color images are refreshed at 480 frames per second. In order to transmit such a high frame-rate signal via conventional 120-Hz DVI, we have introduced a spatiotemporal mapping of image signal. A processor of LED image signal and FPGAs in LED modules have been reprogrammed so that four adjacent pixels in the input image are converted into successive four fields. The pitch of LED panel is 20 mm. The developed 480-fps LED display is utilized for stereoscopic 3D display by use of parallax barrier. The horizontal resolution of a viewed image decreases to one-half by the parallax barrier. This degradation is critical for LED because the pitch of LED displays is as large as tens of times of other flat panel displays. We have conducted experiments to improve quality of the viewed image through the parallax barrier. The improvement is based on interpolation by afterimages. It is shown that the HFR LED provides detailed afterimages. Furthermore, the HFR LED has been utilized for unconscious imaging, which provide a sensation of discovery of conscious visual information from unconscious images.

  15. CHEMICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1965-06-01

    How did life come to be on the surface of the earth? Darwin himself recognized that his basic idea of evolution by variation and natural selection must be a continuous process extending backward in time through that period in which the first living things arose and into the period of 'Chemical Evolution' which preceded it. We are approaching the examination of these events by two routes. One is to seek for evidence in the ancient rocks of the earth which were laid down prior to that time in which organisms capable of leaving their skeletons in the rocks to be fossilized were in existence. This period is sometime prior to approximately 600 million years ago. The earth is believed to have taken its present form approximately 4700 million years ago. We have found in rocks whose age is about 1000 million years certain organic molecules which are closely related to the green pigment of plants, chlorophyll. This seems to establish that green plants were already fluorishing prior to that time. We have now found in rocks of still greater age, namely, 2500 million years, the same kinds of molecules mentioned above which can be attributed to the presence of living organisms. If these molecules are as old as the rocks, we have thus shortened the time available for the generation of the complex biosynthetic sequences which give rise to these specific hydrocarbons (polyisoprenoids) to less than 2000 million years.

  16. Chemical information science coverage in Chemical Abstracts.

    Science.gov (United States)

    Wiggins, G

    1987-02-01

    For many years Chemical Abstracts has included in its coverage publications on chemical documentation or chemical information science. Although the bulk of those publications can be found in section 20 of Chemical Abstracts, many relevant articles were found scattered among 39 other sections of CA in 1984-1985. In addition to the scattering of references in CA, the comprehensiveness of Chemical Abstracts as a secondary source for chemical information science is called into question. Data are provided on the journals that contributed the most references on chemical information science and on the languages of publication of relevant articles.

  17. Nature's chemicals and synthetic chemicals: comparative toxicology.

    OpenAIRE

    Ames, B N; Profet, M; Gold, L S

    1990-01-01

    The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins such as dioxin are compared to natural chemicals, such as indole carbinol (in brocco...

  18. Impact of dimming white LEDs: chromaticity shifts due to different dimming methods

    Science.gov (United States)

    Dyble, Marc; Narendran, Nadarajah; Bierman, Andrew; Klein, Terence

    2005-09-01

    The goal of this study was to characterize the chromaticity shift that mixed-color and phosphor-converted white LED systems undergo when dimmed. As light-emitting diodes continue to rapidly evolve as a viable light source for lighting applications, their color shift while being dimmed should meet the current requirements of traditional lighting sources. Currently, LED system manufacturers commonly recommend pulse-width-modulation or PWM dimming schemes for operation of LED systems. PWM has the ability to achieve lower intensity levels and more linear control of light intensity compared to continuous current dimming methods. However, little data has been published on the effect dimming has on chromaticity shift of white LED lighting systems. The primary objective of this study was to quantify chromaticity shifts in mixed-color and phosphor-converted white LED systems due to continuous current dimming and pulse-width-modulation dimming schemes. In this study, the light output of the LED system was reduced from 100% to 3% by means of continuous current reduction or PWM methods using a PC white LED system and a mixed-color RGB LED system. Experimental results from this study showed that the PC white LED system exhibited very little chromaticity shift (less than a 4-step MacAdam ellipse) when the light level was changed from 100% to 3% using both dimming schemes. Compared to PC white LEDs, the mixed-color RGB LED system tested in this study showed very large chromaticity shifts in a similar dimming range using both dimming schemes. If a mixed-color RGB system is required, then some active feedback system control must be incorporated to obtain non-perceivable chromaticity shift. In this regard the chromaticity shift caused by the PWM method is easier to correct than the chromaticity shift caused by the continuous current dimming method.

  19. Research Review on Silicone Materials for LED Encapsulation%LED 有机硅封装材料的研究进展

    Institute of Scientific and Technical Information of China (English)

    王安营; 张镇玉; 宋超; 毛宁

    2016-01-01

    综述了高、中、低三种折射率LED有机硅封装材料的研究进展,分析了各种产品的优缺点,指出LED有机硅封装材料由低折射率向高折射率快速发展的方向。%The development in the research of low , midium and high refractive index of silicone materials for LED encapsulation were reviewed .The advantages and disadvantages of silicone products were analyzed . Development direction of silicone materials for LED encapsulation was pointed out from low refractive index to a high one .At present , introducing phenyl , diphenyl or other high refractive organic groups of the gum and adding high refractive inorganic nanoparticles , silicone materials for LED encapsulation had high refractive properties.

  20. Direct-lit LED backlight technology for improving the picture quality%改善显示品质的直下式 LED 背光技术

    Institute of Scientific and Technical Information of China (English)

    吴丽; 沈健; 徐立国

    2014-01-01

    Through theoretical analysis,RGB three primaries LED backlighting with appropriate line is chosen in a LCD backlight with narrow gamut,which can raise the color gamut from 40% to 70%. And the test fitted well with analysis,but the mixing ratio of three primaries direct-lit backlight is 1.3∶1,larger than 1 ∶ 1 of full white backlight.The white LEDs were doped into three primaries LED backlight,which can reduce the mixing ratio.As the brightness of the white light increases, color gamut will be reduced.When color gamut changes from 70.2% to 63.7%,the white luminance is 30% of the total luminance,and the mixing ratio is descended to 1.1∶1.%通过理论分析,在窄色域液晶屏的背光中选择合适谱线的 RGB 三基色 LED 背光,可以将显示器的色域从40%提升至70%.试验结果与理论相符合,但是三基色直下式背光的混光比为1.3∶1,比全白灯背光的1∶1大.在三基色LED 背光中加入 LED 白灯,能够降低混光比.白光灯的亮度逐步增加时,色域会降低.当色域从70.2%下降到63.7%时,白灯发出的亮度占总亮度的30%,混光比也降低为1.1∶1.