Relevant bibliographies by topics / Ultraviolet light (UVB)

Academic literature on the topic 'Ultraviolet light (UVB)'

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Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Ultraviolet light (UVB)"

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Wang, Pei-Wen, Yu-Chiang Hung, Tung-Yi Lin, Jia-You Fang, Pei-Ming Yang, Mu-Hong Chen, and Tai-Long Pan. "Comparison of the Biological Impact of UVA and UVB upon the Skin with Functional Proteomics and Immunohistochemistry." Antioxidants 8, no. 12 (November 20, 2019): 569. http://dx.doi.org/10.3390/antiox8120569.

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The skin provides protection against external stimuli; however, solar radiation, including ultraviolet A (UVA) and ultraviolet B (UVB), can result in profound influences on skin structure and function, which eventually impairs its molecular characteristics and normal physiology. In the current study, we performed proteome tools combined with an immunohistological approach on nude mouse skin to evaluate the adverse responses elicited by UVA and UVB irradiation, respectively. Our findings indicated that UVA significantly promotes oxidative damage in DNA, the breakdown of collagen fiber in the dermis, and the apoptosis of fibroblasts, which leads to inflammation. Meanwhile, UVB administration was found to enhance the carbonylation of various proteins and the proliferation of keratinocyte. Particularly, raspberry extract, which has been confirmed to have antioxidative efficacy, could effectively attenuate ultraviolet (UV) radiation-caused cell death. Network analysis also implied that UVA and UVB induce quite different responses, and that UVA results in cell death as well as inflammation mediated by caspase-3 and activator protein 1/nuclear factor kappa-light-chain-enhancer of activated B cells (AP-1/NF-κB), while UVB predominantly increases the risk of skin carcinogenesis involved with oncogenes such as p53 and c-Myc. Taken together, functional proteomics coordinated with histological experiments could allow for a high-throughput study to explore the alterations of crucial proteins and molecules linked to skin impacts subjected to UVA and UVB exposure.
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Bowman, Robert L., Rebecca C. Hennessey, Tirzah J. Weiss, David A. Tallman, Emma R. Crawford, Brandon M. Murphy, Amy Webb, et al. "UVB mutagenesis differs in Nras- and Braf-mutant mouse models of melanoma." Life Science Alliance 4, no. 9 (July 1, 2021): e202101135. http://dx.doi.org/10.26508/lsa.202101135.

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BRAF-mutant melanomas are more likely than NRAS-mutant melanomas to arise in anatomical locations protected from chronic sun damage. We hypothesized that this discrepancy in tumor location is a consequence of the differential sensitivity of BRAF and NRAS-mutant melanocytes to ultraviolet light (UV)-mediated carcinogenesis. We tested this hypothesis by comparing the mutagenic consequences of a single neonatal, ultraviolet-AI (UVA; 340–400 nm) or ultraviolet-B (UVB; 280–390 nm) exposure in mouse models heterozygous for mutant Braf or homozygous for mutant Nras. Tumor onset was accelerated by UVB, but not UVA, and the resulting melanomas contained recurrent mutations affecting the RING domain of MAP3K1 and Actin-binding domain of Filamin A. Melanomas from UVB-irradiated, Braf-mutant mice averaged twice as many single-nucleotide variants and five times as many dipyrimidine variants than tumors from similarly irradiated Nras-mutant mice. A mutational signature discovered in UVB-accelerated tumors mirrored COSMIC signatures associated with human skin cancer and was more prominent in Braf- than Nras-mutant murine melanomas. These data show that a single UVB exposure yields a greater burden of mutations in murine tumors driven by oncogenic Braf.
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Marwood, Christopher A., Ralph EH Smith, John A. Furgal, Murray N. Charlton, Keith R. Solomon, and Bruce M. Greenberg. "Photoinhibition of natural phytoplankton assemblages in Lake Erie exposed to solar ultraviolet radiation." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 2 (February 1, 2000): 371–79. http://dx.doi.org/10.1139/f99-258.

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Photoinhibition was examined in natural assemblages of phytoplankton from Lake Erie exposed to ambient solar radiation. The impacts on photosynthesis of photosynthetically active radiation (400-700 nm) (PAR), ultraviolet-A radiation (320-400 nm) (UVA), and ultraviolet-B radiation (295-320 nm) (UVB) were assessed at three sites on the lake using pulse amplitude modulated chlorophyll fluorescence. Short exposures (<= 30 min) to sunlight containing UVB (1.8-4.4 mmol·m-2) resulted in the rapid loss of up to 60% of photosystem II efficiency (in the dark-adapted state) (Fv/Fm) and quantum yield (in the light-adapted state) (ΔF/F'm). Exposure to UVA (46-105 mmol·m-2) generally diminished Fv/Fm and, to a lesser extent, ΔF/F'm. Short exposures to PAR (733-1588 mmol·m-2) had no significant effects on electron transport. Recovery from UVA- or UVB-induced photoinhibition was complete for Fv/Fm and 90% complete for ΔF/F'm after 2 h in low light. The results indicate that exposures of phytoplankton to surface radiation need only be short in duration to cause substantial UV inhibition of photosynthesis. However, depending on the kinetics of mixing of the water column, recovery of photosynthesis is possible if there is sufficient time for repair of UV damage. Future elevated levels of solar UVB due to ozone depletion could significantly inhibit primary production in mesotrophic lakes such as Lake Erie.
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Zocoler, Marcos Alberto, Joelma Vieira Lopes, Letícia Duarte dos Santos, Guilherme Luiz de Castro Carvalho, and Décio Gomes de Oliveira. "DESENVOLVIMENTO, AVALIAÇÃO DO EFEITO FOTOPROTETOR UVA E UVB, AÇÃO ANTIOXIDANTE E ESTABILIDADE DE UM CREME COM EXTRATOS DE UMBÚ-CAJÁ." Colloquium Vitae 11, no. 3 (December 20, 2019): 51–61. http://dx.doi.org/10.5747/cv.2019.v11.n3.v270.

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The objective of this studywas to evaluate the UVA and UVB photoprotective effect and the antioxidant activity of dermatological cream developed with umbu-cajá (Spondias sp) extracts. The antioxidant activity of the cream was evaluated by the 1,1-diphenyl-2-picrylhydrazine (DPPH) radical inhibition method in triplicate, and the dilutions were evaluated by spectrophotometer, with the absorbance values determined at 517 nm. The evaluation of UVB and UVB photoprotective capacity was performed according to Mansur method and determining the UVA / UVB ratio and the critical wavelength. The developed cream showed antioxidant activity with inhibition close to 80% at 10 mg.mL-1dilution. The spectrophotometer scan showed that the inputs and the cream can absorb ultraviolet light from 290 to 400 nm. The cream with umbu-cajá extract studied had antioxidant and photoprotective properties UVA / UVB and can be used as anti-aging cosmetic.
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Craver, Joshua K., Chad T. Miller, Kimberly A. Williams, and Nora M. Bello. "Ultraviolet Radiation Affects Intumescence Development in Ornamental Sweetpotato (Ipomoea batatas)." HortScience 49, no. 10 (October 2014): 1277–83. http://dx.doi.org/10.21273/hortsci.49.10.1277.

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Intumescences are a physiological disorder characterized by hypertrophy and possibly hyperplasia of plant tissue cells. Ultimately, this disorder results in the death of the affected cells. Previous observations and research suggest that the quality and quantity of light to which plants are exposed may be a factor in development of the disorder. The purpose of this study was to assess the preventive effect of ultraviolet-B (UVB) radiation on intumescence development in ornamental sweetpotato (Ipomoea batatas). Two sweetpotato cultivars, Sidekick Black and Ace of Spades, were grown under light treatments consisting of 1) normal greenhouse production conditions; 2) supplemental UVB lighting; 3) supplemental UVB lighting with Mylar® sleeves over the lamps to block UVB radiation; and 4) control lighting with full spectrum lamps. Treatments were administered for 2 weeks, and the experiment was repeated twice. ‘Ace of Spades’ was highly susceptible to intumescence development, whereas ‘Sidekick Black’ was much less susceptible to the disorder. For ‘Ace of Spades’, the addition of UVB radiation significantly reduced the number of leaves affected with intumescences when compared with plants grown under the other light treatments; this UVB effect was not apparent for ‘Sidekick Black’. Furthermore, there was no evidence for reduced plant growth under UVB light in either cultivar, but side effects from the radiation included leaf discoloration and deformities. This study indicates a cultivar-specific effect of UVB light in preventing intumescence development on ornamental sweetpotato, therefore suggesting a potential genetic component in intumescence susceptibility. These results provide further insight in better understanding intumescence development and how to prevent the disorder.
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Pirc, Matija, Simon Caserman, Polonca Ferk, and Marko Topič. "Compact UV LED Lamp with Low Heat Emissions for Biological Research Applications." Electronics 8, no. 3 (March 21, 2019): 343. http://dx.doi.org/10.3390/electronics8030343.

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Much biomedical research focuses on the effects of UV light on human cells. UV light sources are a prerequisite for such research. This paper presents the design and achieved performance of a UVA (Ultraviolet A: 320–400 nm) and a UVB (Ultraviolet B: 290–320 nm) LED-based lamp suitable for use in bioassays, as well as inside an incubator. Numerical simulations were used to optimise the number, layout and output power of LEDs to achieve good irradiance homogeneity while maintaining low costs. Design was optimised for the efficient transfer of generated heat away from the irradiated samples through the heatsink at the back of the lamps. The average irradiance of the target surface by the UVA lamp was 70.1 W/m2 with a maximum deviation of 4.9%, and the average irradiance by the UVB lamp was 3.1 W/m2 with a maximum deviation of 4.8%. With the UVA and UVB lamps, the temperature of samples undergoing irradiation in the incubator rises from 37 to 42 °C within 40 and 67 min, respectively. This by far exceeds the required UV irradiation time in most cases. Tests on Jurkat and HEK-293 cell cultures confirmed the suitability of our lamps for biomedical research.
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Deeg, HJ, L. Bazar, M. Sigaroudinia, and M. Cottler-Fox. "Ultraviolet B light inactivates bone marrow T lymphocytes but spares hematopoietic precursor cells." Blood 73, no. 2 (February 1, 1989): 369–71. http://dx.doi.org/10.1182/blood.v73.2.369.369.

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Abstract Bone marrow cells from ten normal donors were exposed to ultraviolet (UV)C or UVB light for total exposures of 0.1 to 100 mJ/cm2, and assayed for granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), and phytohemagglutinin (PHA)- stimulated proliferative responses. After exposure to UVC CFU-GM, BFU-E and PHA responses showed a UV dose-dependent sharp decrease to levels less than 1% of controls with 0.5, 2.0, and 10 mJ/cm2, respectively. With UVB, PHA responses were most sensitive, declining to less than 1% at 5 mJ/cm2. BFU-E decreased to less than 1% of control with 15 mJ/cm2 UVB. CFU-GM, at UVB doses of 0.1 to 2.0 mJ/cm2, increased to 125% to 130% of control and decreased to less than 1% only at exposures greater than 20 mJ/cm2. Thus, these studies show that UVB, but not UVC light, can be used to inactivate bone marrow T lymphocytes selectively while sparing hematopoietic precursor cells. The data suggest that UVB irradiation can be used for T-lymphocyte purging for allogeneic marrow transplantation.
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Deeg, HJ, L. Bazar, M. Sigaroudinia, and M. Cottler-Fox. "Ultraviolet B light inactivates bone marrow T lymphocytes but spares hematopoietic precursor cells." Blood 73, no. 2 (February 1, 1989): 369–71. http://dx.doi.org/10.1182/blood.v73.2.369.bloodjournal732369.

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Bone marrow cells from ten normal donors were exposed to ultraviolet (UV)C or UVB light for total exposures of 0.1 to 100 mJ/cm2, and assayed for granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), and phytohemagglutinin (PHA)- stimulated proliferative responses. After exposure to UVC CFU-GM, BFU-E and PHA responses showed a UV dose-dependent sharp decrease to levels less than 1% of controls with 0.5, 2.0, and 10 mJ/cm2, respectively. With UVB, PHA responses were most sensitive, declining to less than 1% at 5 mJ/cm2. BFU-E decreased to less than 1% of control with 15 mJ/cm2 UVB. CFU-GM, at UVB doses of 0.1 to 2.0 mJ/cm2, increased to 125% to 130% of control and decreased to less than 1% only at exposures greater than 20 mJ/cm2. Thus, these studies show that UVB, but not UVC light, can be used to inactivate bone marrow T lymphocytes selectively while sparing hematopoietic precursor cells. The data suggest that UVB irradiation can be used for T-lymphocyte purging for allogeneic marrow transplantation.
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Haag, Robin, Nicole Sieber, and Martin Heßling. "Cataract Development by Exposure to Ultraviolet and Blue Visible Light in Porcine Lenses." Medicina 57, no. 6 (May 27, 2021): 535. http://dx.doi.org/10.3390/medicina57060535.

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Background and Objectives: Cataract is still the leading cause of blindness. Its development is well researched for UV radiation. Modern light sources like LEDs and displays tend to emit blue light. The effect of blue light on the retina is called blue light hazard and is studied extensively. However, its impact on the lens is not investigated so far. Aim: Investigation of the impact of the blue visible light in porcine lens compared to UVA and UVB radiation. Materials and Methods: In this ex-vivo experiment, porcine lenses are irradiated with a dosage of 6 kJ/cm2 at wavelengths of 311 nm (UVB), 370 nm (UVA), and 460 nm (blue light). Lens transmission measurements before and after irradiation give insight into the impact of the radiation. Furthermore, dark field images are taken from every lens before and after irradiation. Cataract development is illustrated by histogram linearization as well as faults coloring of recorded dark field images. By segmenting the lens in the background’s original image, the lens condition before and after irradiation could be compared. Results: All lenses irradiated with a 6 kJ/cm2 reveal cataract development for radiation with 311 nm, 370 nm, and 460 nm. Both evaluations reveal that the 460 nm irradiation causes the most cataract. Conclusion: All investigated irradiation sources cause cataracts in porcine lenses—even blue visible light.
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Setaluri, Vijay, Adele R. Clark, and Steven R. Feldman. "Transmittance Properties of Flurandrenolide Tape for Psoriasis: Helpful Adjunct to Phototherapy." Journal of Cutaneous Medicine and Surgery 4, no. 4 (October 2000): 196–98. http://dx.doi.org/10.1177/120347540000400404.

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Background: Flurandrenolide tape is a valuable agent in the treatment of lichen simplex chronicus and in psoriasis. The corticosteroid is helpful for reducing the symptoms and induration of the lichen simplex chronicus lesion, and occlusion of the lesion with the tape reduces the patient's opportunity to rub and scratch the affected area. Objective: The purpose of this study was to determine to what extent flurandrenolide tape may block ultraviolet (UV) light and interfere with phototherapy of psoriasis. Methods: Flurandrenolide tape was applied to quartz spectroscopy cuvettes, and the absorption spectrum was determined using a Beckman DU-600 spectrophotometer. The effect of the tape on UV light transmission was also determined using our UVA-UVB office phototherapy unit. Results: Flurandrenolide tape has considerable UV absorption in the UVC range with less absorption in the UVB and UVA range. The transmittance is greater (less absorption) with longer wavelengths. There was greater UV absorption in the UVB range than in the UVA range. Conclusion: Although flurandrenolide tape may be left in place during PUVA therapy, adjustment of UV dose or removal of the tape is probably needed during UVB phototherapy.
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Dissertations / Theses on the topic "Ultraviolet light (UVB)"

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Grady, George. "The effect of resveratrol on ultraviolet light-induced skin cell death." Marietta College Honors Theses / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=marhonors1366909727.

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Thomas-Ahner, Jennifer M. "Gender differences in UVB induced cutaneous inflammation and skin carcinogenesis." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1179949864.

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Endoh, Ikuko Medical Sciences Faculty of Medicine UNSW. "New mechanisms of regulation of mast cell activation." Publisher:University of New South Wales. Medical Sciences, 2008. http://handle.unsw.edu.au/1959.4/42937.

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Mast cells (MCs) play a central role in inflammation by releasing mediators following activation. S100A8 and S100A9 are abundantly expressed in inflammatory sites such as asthmatic lung, sunburnt skin and atherosclerosis where MCs are involved in pathogenesis; roles of S100A8 in MC function are undetermined. The aims of this thesis were to determine effects of S100A8 on MC activation, particularly provoked by IgE and UVB. Initially, effects of UVB on MC activation were investigated as detailed functions were unclear. Cord blood-derived human mast cells (CBMCs) were treated in vitro with varying doses of UVB and production of multiple cytokines and viability investigated. UVB exposure selectively increased levels of IL-8 (CXCL8), and to a less extent IL-1β, but not eight other cytokines tested. New protein synthesis partially contributed and IL-8 production was p38 MAPK-dependent. UVB dose-dependently induced MC apoptosis indicating a potential regulatory mechanism of MC function. The ability of recombinant S100A8, S100A9 or S100A8/9 heterodimer to modulate IgE/antigen (DNP/anti-DNP)-mediated activation of a murine MC line, and of bone marrow-derived (mBM) MC activation was determined. The S100s did not directly induce degranulation or induce IL-6. S100A8 significantly inhibited DNP/anti-DNP-provoked degranulation, and IL-6 and TNF mRNA and protein induction. S100A8 did not alter FcεRIα expression. S100A9 was less effective; and the S100A8/9 complex was also suppressive. S100A8 only weakly suppressed non-specific MC degranulation. Mutation of Cys41 in S100A8 negated its suppressive activity. Because S100A8 scavenges oxidants via this reactive Cys residue, we propose that this may mediate its ability to downmodulate IgE-dependent MC responses. Similar to the thiol scavenger N-acetyl-L-cysteine, S100A8 but not the Ala41 mutant, attenuated DNP/anti-DNP-provoked LAT phosphorylation. However, the disulfide-bonded S100A8 dimer and S100A8 containing a sulfinamide bond between Cys41 and Lys34/35 also reduced MC activation, indicating an additional pathway(s). S100A8 did not suppress antigen/IgE-induced responses of CBMC possibly because these may not truly reflect fullymature human tissue MCs. S100A8 did not alter UVB-induced IL-8 release by CBMCs, or affect apoptosis. Murine S100A8 may have anti-inflammatory properties by regulating MC activation in an activator-specific manner, at least partially by scavenging ROS to suppress intracellular signalling.
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Wulff, Brian Charles. "Effects of Therapeutic Immunosuppressants on UVB Induced Inflammation and Skin Carcinogenesis in a Murine Model." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1227116356.

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Saul, Alison Nicole. "Psycho-physiological stress and its effects on ultraviolet light induced inflammation, DNA damage, and skin carcinogenesis." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1172850801.

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Habtemichael, Yishak Tekleab. "Packaging designs for ultraviolet light emitting diodes." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45764.

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Aluminum Gallium Nitride (AlGaN) / Gallium Nitride (GaN) based deep ultraviolet (DUV) light emitting didoes (LEDs) with emission wavelengths between 200-280 nm enable key emerging technologies such as water/air purification and sterilization, covert communications and portable bio-agent detection/identification systems for homeland security, and surface and medical device sterilization. These devices produce a large amount of undesired heat due to low quantum efficiencies in converting electrical input to optical output. These low efficiencies are attributed to difficulties in the growth&doping of AlₓGa₁₋ₓN materials and UV absorbing substrates leading to excessive joule heating, which leads to device degradation and a spectral shift in the emission wavelength. With this regard, effective thermal management in these devices depends on the removal of this heat and reduction of the junction temperature. This is achieved by decreasing the package thermal resistance from junction-to-air with cost-effective solutions. The use of heat sinks, thermal interface materials, and high conductivity heat spreaders is instrumental in the reduction of the overall junction-to-air thermal resistance. This thesis work focuses on thermal modeling of flip-chip packaged deep UV LEDs to gain a better understanding of the heat propagation through these devices as well as the package parameters that have the biggest contributions to reducing the overall thermal resistance. A parametric study focusing on components of a lead frame package is presented to ascertain the thermal impacts of various package layers including contact metallizations, thermal spreading sub-mounts, and thermal interface materials. In addition the use of alternative thermal interface materials such as phase change materials and liquid metals is investigated experimentally.
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Rocha, Artur Batista de Oliveira 1982. "Efeitos da radiação UV-C e da luz fluorescente no controle fitossanotário e na indução de resistência em batata-semente após a colheita." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256741.

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Orientadores Sylvio Luis Honório, Claudio Luiz Messias
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
Made available in DSpace on 2018-08-27T23:01:54Z (GMT). No. of bitstreams: 1 Rocha_ArturBatistadeOliveira_D.pdf: 1714662 bytes, checksum: 577fdeb54b226ba61587e77781ac70cf (MD5) Previous issue date: 2015
Resumo: O cultivo da batateira (Solanum tuberosum L.) apresenta problemas fitossanitários decorrentes do ataque de pragas e doenças, o que acarreta altos cultos de produção. As principais doenças pós-colheita em batata-semente são: podridão seca (agente causal: Fusarium solani), rhizoctoniose (agente causal: Rhizoctonia solani) e podridão mole (agente causal: Pectobacterium carotovorum subsp. carotovorum). Os principais glicoalcaloides presentes na batata são a ?-chaconina e ?-solanina, os quais possuem propriedades antimicrobianas e podem ser estimulados por diversos fatores, com destaque para a luz. O objetivo desta pesquisa foi investigar a aplicação da radiação ultravioleta UV-C e da luz fluorescente no controle dos patógenos Fusarium solani, Rhizoctonia solani e Pectobacterium carotovorum subsp. carotovorum nas cultivares Ágata, Atlantic e Monalisa de batata-semente após a colheita. A pesquisa foi realizada em duas etapas: (I) avaliou-se in vitro o efeito da radiação UV-C no desenvolvimento das colônias de F. solani e de R. solani e na germinação dos conídios de F. solani. In vivo avaliou-se o efeito da radiação UV-C e da luz fluorescente na severidade e na incidência de podridão seca e de rhizoctoniose na brotação, na perda de massa e no teor de sólidos solúveis em batata-semente 'Agata' e 'Atlantic'; (II): avaliou-se in vitro o efeito da radiação UV-C no desenvolvimento das colônias de P. carotovorum subsp. carotovorum. In vivo avaliou-se o efeito da radiação UV-C e da luz fluorescente na severidade e na incidência da podridão mole, na concentração de ?-chaconina e de ?-solanina, na brotação, na perda de massa e no teor de sólidos solúveis em batata-semente 'Agata' e 'Monalisa'. A exposição de F. solani e R. solani a uma densidade de energia de 105,6 kJ.m-2 de radiação UV-C diminui o desenvolvimento das colônias desses fungos para estudos in vitro. Para a germinação de conídios de F. solani foi exposta a uma densidade de energia de 52,8 kJ.m-2 de radiação UV-C. Além disso, a luz fluorescente foi mais eficaz do que a radiação UV-C para o controle da podridão seca e da rhizoctoniose, sem afetar a brotação. A exposição de P. carotovorum subsp. carotovorum na densidade de energia de 34,5 kJ.m-2 de radiação UV-C inibiu o desenvolvimento das colônias para estudos in vitro. A luz fluorescente foi mais eficaz do que a radiação UV-C para controle da podridão mole em tubérculos de batata, assim como, estimulou a síntese de glicoalcaloides. O controle da podridão mole em tubérculos de batata está relacionado a maior concentração de ?-chaconina e ?-solanina, especialmente na periderme. Os teores de ?-chaconina (11,6 a 26,0 mg.kg-1P.F.) e ?-solanina (11,4 a 25,1 mg.kg-1P.F.) mostraram-se eficazes para o controle da podridão mole. Além disso, a brotação não foi afetada de forma adversa
Abstract: The cultivation of potato (Solanum tuberosum L.) in the tropics suffers the attack of pests and diseases, burdening the cost of production. The main postharvest diseases in potato seeds are the dry rot (pathogen: Fusarium solani), black scab (pathogen: Rhizoctonia solani) and wet rot (pathogen: Pectobacterium carotovorum subsp. carotovorum. The efficiency of UV-C against a wide variety of microorganisms has been reported and there is interest in applying for seed disinfection. Potato plants contain glycoalkaloids being ?-chaconine and ?-solanine the main ones. The accumulation of these glycoalkaloids can be stimulated by several factors, especially light, having them important antimicrobial properties. The aim of this research was to evaluate the the postharvest application of ultraviolet (UV-C) radiation and the fluorescent light to control the pathogens: F. solani, R. solani, and P. carotovorum subsp. carotovorum on 'Agata', 'Atlantic', and 'Monalisa' potato seeds. The research was conducted in two stages: (I) the evaluation in vitro of the effect of UV-C radiation on the growth of F. solani and R. solani colonies and F. solani conidias germination and the in vivo effect of UV-C radiation and fluorescent light on dry rot and black scab severity and incidence, mass loss and soluble solids content on 'Agata' and 'Atlantic' and (II) the evaluation in vitro of the effect of UV-C radiation on P. carotovorum subsp. carotovorum colonies and was reported in vivo the effect of UV-C radiation and the fluorescent light on the severity and incidence of wet rot, ?-chaconine and ?-solanine, concentration, tuber sprouting, weight loss and soluble solids on 'Agata' and 'Monalisa'. Exposure of R. solani and F. solani at an energy density of 105,6 kJ.m-2 of UV-C radiation decreases the development of fungi colonies in vitro. Energy density of 52,8 kJ.m-2 inhibited the F. solani conidias germination. Moreover the fluorescent light was more effective than UV-C radiation to control dry root and black scab, without affecting the sprouting. The in vivo experiments showed that treated and untreated. UV-C tubers stored under fluorescent light were more effective to control soft rot than the UV-C treated tubers and stored under darkness. Control tubers under fluorescent light, UV-C treated under darkness, and UV-C treated under fluorescent light showed an increased concentration of ?-chaconine (11,6 to 26,0 mg.kg-1F.W.) and ?-solanine (11,4 a 25,1 mg.kg-1F.W.) for both cultivars
Doutorado
Tecnologia Pós-Colheita
Doutor em Engenharia Agrícola
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Makdoumi, Karim. "Ultraviolet light A (UVA) photoactivation of riboflavin as a potential therapy for infectious keratitis." Doctoral thesis, Örebro universitet, Hälsoakademin, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-20130.

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Ayoub, Lore Michele. "Can colored dissolved organic material protect coral reefs by reducing exposure to ultraviolet radiation?" [Tampa, Fla.] : University of South Florida, 2009. http://digital.lib.usf.edu/?e14.2918.

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Saifaddin, Burhan Khalid. "Development of Deep Ultraviolet (UV-C) Thin-Film Light-Emitting Diodes Grown on SiC." Thesis, University of California, Santa Barbara, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10975858.

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UV-C LEDs in the range of 265–280 nm are needed to develop new disinfection and biotechnology applications. The market share for UV-C LED, versus UV-C lamps (Hg discharge and Xe), increased from 8% in 2008 ($240M) to 25% in 2018 ($810M). However, while low-pressure mercury lamps are ~30% energy efficient, the best commercial UV-C LEDs in the 265–280 nm range are ~2% energy efficient; InGaN blue LEDs are 80% energy efficient. Research on AlGaN LEDs has made significant progress into AlGaN material quality (including threading dislocation density and n-AlGaN electrical conductivity) but has lagged regarding light extraction efficiency. Light extraction from UV LEDs is limited by p-GaN absorption because of the lack of p-contact to p-AlGaN with AlN fraction (AlN content > 50%). Furthermore, AlGaN emitters at the 265–280 nm range emit 40–50% of their emissions as transverse magnetic (TM) waves, which are harder to extract than transverse electric (TE) waves.

SiC is an absorbing substrate that has been largely overlooked in developing UV-C LEDs, even though it has a small lattice mismatch with AlN (~1%) and a similar Wurtzite crystal structure and is more chemically stable. We demonstrate the first lateral thin-film flip-chip (TFFC) ultraviolet (UV) light-emitting diodes grown on SiC. UV LEDs were made at 310 nm, 298 nm, 278 nm, and 265 nm.

In this dissertation, we discuss the design, epi development, and fabrication of TFFC AlGaN LEDs with reflective p-contacts. The AlGaN:Mg growth temperature and the Mg doping profile in AlGaN:Mg were found to significantly impact the electroluminescence (EL) efficiency of the AlGaN MQWs. KOH roughening enhanced the light-extraction efficiency (LEE) by 100% and by ~180–200% for UV LEDs with 10 nm p-GaN and 5 nm p-GaN, respectively, without affecting the devices’ IV characteristics. The thin-film architecture led to a high LEE of about ~28–30% without LED encapsulation when used with LEDs with 5 nm p-GaN. The best light extraction efficiency in the literature is ~24% (without LED encapsulation) for a 275 nm flip-chip LED grown on PSS sapphire substrate. KOH roughening of AlN is discussed and is compared to KOH roughening of N-Face GaN. To advance LEE further, we attempted to develop LEDs with transparent current n-AlGaN spreading layers as well as highly doped n+-AlGaN tunnel junctions on top of UV-C LEDs. Reflective and ohmic n-contacts with low resistivities were developed for the n-Al.58Ga.42N regrown by MBE. Furthermore, a highly reflective MgF2/Al omnidirectional mirror was developed, which can be used with n-contact microgrid to further enhance the LEE in UV-C LEDs with a transparent tunnel junction.

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Books on the topic "Ultraviolet light (UVB)"

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Bishop, James. Vertical mixing and methane photochemistry in the atmsophere of Uranus: Analysis of Voyager UVS occultation experiments. [Washington, D.C: National Aeronautics and Space Administration, 1991.

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Araújo, Ana Cláudia Vaz de. Síntese de nanopartículas de óxido de ferro e nanocompósitos com polianilina. Brazil Publishing, 2021. http://dx.doi.org/10.31012/978-65-5861-120-2.

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In this work magnetic Fe3O4 nanoparticles were synthesized through the precipitation method from an aqueous ferrous sulfate solution under ultrasound. A 23 factorial design in duplicate was carried out to determine the best synthesis conditions and to obtain the smallest crystallite sizes. Selected conditions were ultrasound frequency of 593 kHz for 40 min in 1.0 mol L-1 NaOH medium. Average crystallite sizes were of the order of 25 nm. The phase obtained was identified by X-ray diffractometry (XRD) as magnetite. Scanning electron microscopy (SEM) showed polydisperse particles with dimensions around 57 nm, while transmission electron microscopy (TEM) revealed average particle diameters around 29 nm, in the same order of magnitude of the crystallite size determined with Scherrer’s equation. These magnetic nanoparticles were used to obtain nanocomposites with polyaniline (PAni). The material was prepared under exposure to ultraviolet light (UV) or under heating, from dispersions of the nanoparticles in an acidic solution of aniline. Unlike other synthetic routes reported elsewhere, this new route does not utilize any additional oxidizing agent. XRD analysis showed the appearance of a second crystalline phase in all the PAni-Fe3O4 composites, which was indexed as goethite. Furthermore, the crystallite size decreases nearly 50 % with the increase in the synthesis time. This size decrease suggests that the nanoparticles are consumed during the synthesis. Thermogravimetric analysis showed that the amount of polyaniline increases with synthesis time. The nanocomposite electric conductivity was around 10-5 S cm-1, nearly one order of magnitude higher than for pure magnetite. Conductivity varied with the amount of PAni in the system, suggesting that the electric properties of the nanocomposites can be tuned according to their composition. Under an external magnetic field the nanocomposites showed hysteresis behavior at room temperature, characteristic of ferromagnetic materials. Saturation magnetization (MS) for pure magnetite was ~ 74 emu g-1. For the PAni-Fe3O4 nanocomposites, MS ranged from ~ 2 to 70 emu g-1, depending on the synthesis conditions. This suggests that composition can also be used to control the magnetic properties of the material.
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Book chapters on the topic "Ultraviolet light (UVB)"

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Cruz, Ponciano D. "Effects of Ultraviolet B (UVB) Radiation on Induction of Cutaneous Immune Responses." In Biologic Effects of Light, edited by Michael F. Holick and Albert M. Kligman, 97–103. Berlin, Boston: De Gruyter, 1992. http://dx.doi.org/10.1515/9783110856156-015.

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Johnson, Brian E., Cathy Green, Thiruvellor Lakshmipathi, and James Ferguson. "Ultraviolet Radiation Phototherapy for Psoriasis The Use of a New Narrow Band Uvb Fluorescent Lamp." In Light in Biology and Medicine, 173–79. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0709-9_22.

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Ferguson, Gary W., William H. Gehrmann, Stephen H. Hammack, Tai C. Chen, and Michael F. Holick. "Effects of Dietary Vitamin D and UVB Irradiance on Voluntary Exposure to Ultraviolet Light, Growth and Survival of the Panther Chameleon." In Biologic Effects of Light 2001, 193–203. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0937-0_19.

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Al-Awadhi, Safaa, and Mustafa Al-Shemali. "Spectro Absorption." In Atlas of Fallen Dust in Kuwait, 206–46. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66977-5_9.

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Abstract Ultraviolet–visible UV-VIS. Varian Bio Cary 100 UV–VIS instrument was used for measuring the spectrum of dust samples. The certified materials according to Lab sphere SRS. 99–020 were used and the dust samples were placed in a cuvette (10 mm) and placed on the diffuse reflectance accessory. Measurement was done with respect to the reference. The UV–VIS spectra cover the regions from 900 to 190 nm which includes the near-infrared region, visible light regions, and ultraviolet regions. The FT-IR data shows the different chemical content of dust in the scanning of what possible compounds can be found in dust particles for required further analysis. The dust absorption of the light spectrum in Kuwait was revealed in maps according to seasons showing higher and lower concentrations of light absorption of ultraviolet, violet, blue, cyan, green, yellow, orange, red, infrared.
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Rass, Jens, and Neysha Lobo-Ploch. "Optical Polarization and Light Extraction from UV LEDs." In III-Nitride Ultraviolet Emitters, 137–70. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24100-5_6.

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Krutmann, J., U. Trefzer, W. Czech, F. Parlow, A. Budnik, M. Grewe, S. Sinn, A. Kapp, and E. Schöpf. "Effects of Ultraviolet (UV) Light on Inflammatory Skin Disease." In Biologic Effects of Light, edited by Michael F. Holick and Albert M. Kligman, 111–19. Berlin, Boston: De Gruyter, 1992. http://dx.doi.org/10.1515/9783110856156-017.

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Čiplys, D., A. Sereika, R. Rimeika, R. Gaska, M. Shur, J. Yang, and M. Asif Khan. "III-Nitride Based Ultraviolet Surface Acoustic Wave Sensors." In UV Solid-State Light Emitters and Detectors, 239–46. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2103-9_19.

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Richter, Eberhard, Sylvia Hagedorn, Arne Knauer, and Markus Weyers. "Vapor Phase Epitaxy of AlGaN Base Layers on Sapphire Substrates for Nitride-Based UV-Light Emitters." In III-Nitride Ultraviolet Emitters, 47–73. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24100-5_3.

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Cassar, Joshua R., Beining Ouyang, Kathiravan Krishnamurthy, and Ali Demirci. "Microbial Decontamination of Food by Light-Based Technologies: Ultraviolet (UV) Light, Pulsed UV Light (PUV), and UV Light-Emitting Diodes (UV-LED)." In Food Engineering Series, 493–521. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-42660-6_19.

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Modir, James G., and Mark S. Wallace. "Human Experimental Pain Models 1: The Ultraviolet Light UV-B Pain Model." In Methods in Molecular Biology, 159–64. Totowa, NJ: Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60327-323-7_12.

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Conference papers on the topic "Ultraviolet light (UVB)"

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Lee, Jihye, Sang-Wook Chun, Ho-Jong Kang, and Frank E. Talke. "The Effect of UV Stabilizer on the Photo Degradation of Perfluoropolyether Lubricants Used in Hard Disk." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44284.

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Ultraviolet (UV) light exposure can lead to photo degradation of perfluoropolyether (PFPE) lubricants, resulting in a change of their physical properties. In this paper, 2,3,4,5,6-pentafluorobenzophenone was used as ultraviolet stabilizer (UVS) to slow down the photo degradation of PFPE. PFPE/UVS mixtures were exposed to UV light and the mechanism of photo degradation was studied with nuclear magnetic resonance (NMR). Small amounts of UVS (less than 0.3 wt%) were found to effectively stabilize both UV photo degradation at the main chain and the end chain of PFPE.
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Li, Huiyu, Xufang Zhang, and Hornsen Tzou. "Frequency Control of Light-Activated Shape Memory Polymer Laminated Beams: Characterization and Experiments." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59818.

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Light-activated shape memory polymers (LaSMPs) exhibit stiffness variations when exposed to ultraviolet (UV) lights. Thus, LaSMP could manipulate structural natural frequencies with UV light exposures when laminated on structures. This study aims to experimentally demonstrate the effectiveness of LaSMP frequency control of a flexible beam. The natural frequency of a three-layered Euler-Bernoulli beam composed of LaSMP, adhesive tape and the flexible beam is analyzed and its frequency formulation exhibits the LaSMP stiffness influence. As the LaSMP adopted in this study is a new spiropyran based composition, a generic Young’s modulus model is proposed and then simplified to model the present LaSMP composition. To make sure the experiment is carried out in a homogenous light field, the light intensities of the UV surface light source at different positions are tested. The temperature change of the LaSMP sample under UV exposures is also measured. The time constant of the reverse reaction and the threshold intensity of the reverse reaction are measured. LaSMP Young’s modulus variation is tested with a uniaxial tension experiment. The constitutive model of LaSMP’s Young’s modulus is validated by experimental data. With these preparations, the LaSMP laminated flexible beam model is exposed to the UV lights and its natural frequencies are identified with a data acquisition and analysis system. The maximum natural frequency variation ratio achieves 5.67%. Comparing both theoretical and experimental data of natural frequency control, this study also validates the LaSMP Young’s modulus constitutive model.
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Fernandes, Fabiano Andre Narciso, Thayane Rabelo Braga, Ebenezer Oliveira Silva, and Sueli Rodrigues. "Drying of mangoes applying pulsed UV light as pre-treatment." In 21st International Drying Symposium. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7303.

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High intensity pulsed UV Light is a non-thermal treatment used in sanitization of fruits and vegetables. In this work, we have applied high intensity pulsed UV light as a pretreatment for convective air-drying evaluating the benefits of the pretreatment to the drying process and to the nutritional quality of the dried product. Mangoes were subjected to pulses of UV light. The pretreated samples were further dried in a convective oven-drier until 90% of the initial water content has been removed. Drying kinetics, water apparent diffusivity, vitamin B, vitamin C content and total carotenoids content were analyzed. Pulsed UV light showed to be an interesting pretreatment for mangoes given the higher nutritional content of the dried product. Keywords: mango; drying; ultraviolet; vitamins; kinetics
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Lu, F., X. J. Wang, and Y. F. Liu. "Experimental Research on Deflection Control of Cantilever Beam Based on Hybrid Photovoltaic/Piezoelectric Actuation Mechanism." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65629.

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When ultraviolet light illuminates on polarized PLZT ceramic, a large voltage can be generated between the electrodes due to the anomalous photovoltaic effect. The shape control of flexible shell can be realized by using hybrid photovoltaic/piezoelectric actuation. In this paper, a novel non-contact deflection closed-loop control model of cantilever beam based on hybrid photovoltaic/piezoelectric actuation can be proposed. The photovoltage of PLZT ceramic irradiated by ultraviolet light is applied to drive PVDF actuator. The closed-loop control equations of deflection of cantilever beam is derived based on the mathematical model of PLZT ceramic with coupled multi-physics fields and the constitutive model of cantilever beam. Then, parameters of deflection control equations of cantilever beam during illumination phase and light off phase are identified through the deflection static experiment. After that, the deflection closed-loop control experiment of cantilever beam based on hybrid photovoltaic/piezoelectric actuation mechanism is carried out to verify the control model. The experimental results show that the deflection of cantilever beam with a simple on-off control method can achieve the target value by applying UV light to PLZT ceramic. It also should be noted that, the deflection curve of cantilever beam illuminated by strong UV light has an undesirable fluctuation.
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Shur, Michael S. "Emerging applications of deep ultraviolet light emitting diodes." In UV and Higher Energy Photonics: From Materials to Applications 2021, edited by Gilles Lérondel, Yong-Hoon Cho, and Atsushi Taguchi. SPIE, 2021. http://dx.doi.org/10.1117/12.2592244.

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Liu, Xiaolu, Yang Liu, Kai Ren, Paul Lawson, Andrew Moening, Matthew Haubert, Yong X. Gan, et al. "Clean Energy Generation by a Nanostructured Biophotofuel Cell." In ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2013 Heat Transfer Summer Conference and the ASME 2013 7th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fuelcell2013-18261.

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In this paper, clean energy generation from hazardous materials by a nanostructured biophotofuel cell was studied. Specifically, electrodeposition of polyaniline on TiO2 nanotube as photoelectrochemical anode for a sodium sulfide fuel cell was performed. The photoelectrochemical response of the TiO2 nanotube capped by polyaniline nanoparticles was studied in UV and visible light illumination using sodium sulfide as the electrolyte. The polyaniline was added onto the top end of the nanotube via electrochemical deposition from 0.1 M aniline (C6H7N) in 1 M HCl solution. Polyaniline nanoparticle/TiO2 nanotube was made into an anode and put into 0.5 M sodium sulfide solution for photoelectrochemical response tests under both visible and ultraviolet light irradiation. The photoelectrochemical anode shows good photo-catalytic property, as evidenced by the open circuit potential changes when the illumination conditions were changed. Its response to ultraviolet light is much stronger than to visible light. It is also found that the higher the temperature of the sodium sulfide solution, the weaker the photo-catalytic response of the anode.
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Lapina, Victoria A., and Alexander E. Dontsov. "Action of UV-A and blue light on enzymes activity and accumulation of lipid peroxidation products in attached and detached frog retinas." In Ultraviolet Radiation Hazards. SPIE, 1994. http://dx.doi.org/10.1117/12.180819.

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Razeghi, Manijeh. "Deep ultraviolet light-emitting diodes and photodetectors for UV communications." In Integrated Optoelectronic Devices 2005, edited by Louay A. Eldada and El-Hang Lee. SPIE, 2005. http://dx.doi.org/10.1117/12.590880.

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Chowdhury, Sadiyah Sabah, Catherine Kent, Sean P. Hill, Enric Baduell, Kenneth Hanson, and William S. Oates. "Experimental Characterization and Modeling of Photon Upconversion in Azobenzene Photomechanical Polymers." In ASME 2015 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/smasis2015-8920.

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Azobenzene polymers show promising photostrictive behavior for a broad range of applications in flow control, robotics, and energy harvesting applications. The conversion of solar energy directly into mechanical work provides unique capabilities in adaptive structures; however, the energy conversion of visible light into mechanical work presents several material chemistry challenges. Azobenzene strongly absorbs ultraviolet (UV) light and blue/green light which limits the efficiency of the photomechanical response under solar irradiation. Photon upconversion — combining two or more low energy photons (longer wavelength) to generate a higher energy excited state (shorter wavelength), provides an intriguing strategy to drive these high energy photochemical reactions with low energy light. We present an experimental study showing the feasibility to drive azobenzene photoisomerization using visible light via select up-conversion molecules in the fluidic state. Multi-physics modeling is then used to predict advances in photomechanical energy conversion when up-conversion molecules are introduced within an azobenzene polymer.
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Cheng, Hao, Zi Zhou Yang, Yang Peng, Yun Mou, and Ming Xiang Chen. "Low Temperature Fabrication of Three-Dimensional Ceramic Substrate by Using Inorganic Alkali Activated Aluminosilicate Cement Paste for UV-LED Packaging." In ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ipack2018-8226.

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In this work, a low temperature method is proposed for the economical fabrication of three-dimensional (3D) ceramic substrate for Ultraviolet Light-Emitting Diodes (UV-LED) packaging. The 3D ceramic substrate using the inorganic alkali activated aluminosilicate cement paste (IAAACP) is molded by sacrificing the patterned wax mold. By controlling the viscosity, milling time, and curing temperature the of the IAAACP, the high strength 3D ceramic substrate is achieved, the corresponding shear strength reaches to 12.5MPa. After thermal shock and heat resistant test, the shear strength changed slightly, indicating the 3D ceramic substrate has excellent thermal reliability. These experimental results indicate that the prepared 3D ceramic substrate has a potential application for UV-LED packaging.
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Reports on the topic "Ultraviolet light (UVB)"

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Moores, Lee, Alan Kennedy, Lauren May, Shinita Jordan, Anthony Bednar, Stacy Jones, David Henderson, Luke Gurtowski, and Kurt Gust. Identifying degradation products responsible for increased toxicity of UV-degraded insensitive munitions. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42020.

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Degradation of insensitive munitions (IMs) by ultraviolet (UV) light has become a concern following observations that some UV-degradation products have increased toxicity relative to parent compounds in aquatic organisms. This investigation focused on the Army's IM formulation, IMX-101, composed of three IM constituents: 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine (NQ). The IM constituents and IMX-101 were irradiated in a UV photo-reactor and then administered to Daphnia pulex in acute (48 h) exposures comparing toxicities relative to the parent materials. UV-degradation of DNAN had little effect on mortality whereas mortality for UV-degraded NTO and NQ increased by factors of 40.3 and 1240, making UV-degraded NQ the principle driver of toxicity when IMX-101 is UV-degraded. Toxicity investigations for specific products formed during UV-degradation of NQ, confirmed greater toxicity than the parent NQ for degradation products. Summation of the individual toxic units for the complete set of individually measured UV-degradation products identified for NQ only accounted for 25% of the overall toxicity measured in the exposures to the UV-degraded NQ product mixture. Given the underestimation of toxicity using the sum toxic units for the individually measured UV-degradation products of NQ, we conclude that: (1) other unidentified NQ degradation products contributed principally to toxicity and/or (2) synergistic toxicological interactions occurred among the NQ degradation product mixture that exacerbated toxicity.
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