Program of polarization studies and capabilities of accelerating polarized proton and light nuclear beams at the nuclotron of the joint institute for nuclear research

NASA Astrophysics Data System (ADS)

Vokal, S.; Kovalenko, A. D.; Kondratenko, A. M.; Kondratenko, M. A.; Mikhailov, V. A.; Filatov, Yu. N.; Shimanskii, S. S.

2009-01-01

A program of polarization studies is presented; this program can enhance our understanding of the constituents from which the spin of hadrons and lightest nuclei is constructed. Beams of polarized lightest nuclei at Nuclotron are required to complete this program. Calculations of linear resonance strengths at Nuclotron, which may result in depolarization effects, are presented. The application of a new method for conserving particle beam polarization at crossing these resonances at Nuclotron is discussed.

Multi-Year Program Plan FY'09-FY'15 Solid-State Lighting Research and Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2009-03-01

President Obama's energy and environment agenda calls for deployment of 'the Cheapest, Cleanest, Fastest Energy Source - Energy Efficiency.' The Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy (EERE) plays a critical role in advancing the President's agenda by helping the United States advance toward an energy-efficient future. Lighting in the United States is projected to consume nearly 10 quads of primary energy by 2012.3 A nation-wide move toward solid-state lighting (SSL) for general illumination could save a total of 32.5 quads of primary energy between 2012 and 2027. No other lighting technology offers the DOE andmore » our nation so much potential to save energy and enhance the quality of our built environment. The DOE has set forth the following mission statement for the SSL R&D Portfolio: Guided by a Government-industry partnership, the mission is to create a new, U.S.-led market for high-efficiency, general illumination products through the advancement of semiconductor technologies, to save energy, reduce costs and enhance the quality of the lighted environment.« less

Design and implementation of a scene-dependent dynamically selfadaptable wavefront coding imaging system

NASA Astrophysics Data System (ADS)

Carles, Guillem; Ferran, Carme; Carnicer, Artur; Bosch, Salvador

2012-01-01

A computational imaging system based on wavefront coding is presented. Wavefront coding provides an extension of the depth-of-field at the expense of a slight reduction of image quality. This trade-off results from the amount of coding used. By using spatial light modulators, a flexible coding is achieved which permits it to be increased or decreased as needed. In this paper a computational method is proposed for evaluating the output of a wavefront coding imaging system equipped with a spatial light modulator, with the aim of thus making it possible to implement the most suitable coding strength for a given scene. This is achieved in an unsupervised manner, thus the whole system acts as a dynamically selfadaptable imaging system. The program presented here controls the spatial light modulator and the camera, and also processes the images in a synchronised way in order to implement the dynamic system in real time. A prototype of the system was implemented in the laboratory and illustrative examples of the performance are reported in this paper. Program summaryProgram title: DynWFC (Dynamic WaveFront Coding) Catalogue identifier: AEKC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKC_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 10 483 No. of bytes in distributed program, including test data, etc.: 2 437 713 Distribution format: tar.gz Programming language: Labview 8.5 and NI Vision and MinGW C Compiler Computer: Tested on PC Intel ® Pentium ® Operating system: Tested on Windows XP Classification: 18 Nature of problem: The program implements an enhanced wavefront coding imaging system able to adapt the degree of coding to the requirements of a specific scene. The program controls the acquisition by a camera, the display of a spatial light modulator and the image processing operations synchronously. The spatial light modulator is used to implement the phase mask with flexibility given the trade-off between depth-of-field extension and image quality achieved. The action of the program is to evaluate the depth-of-field requirements of the specific scene and subsequently control the coding established by the spatial light modulator, in real time.

Using National Coastal Assessment Data to Model Estuarine Water Quality at Large Spatial Scales.

EPA Science Inventory

The water quality of the Nation’s estuaries is attracting scrutiny in light of population growth and enhanced nutrient delivery. The USEPA has evaluated water quality in the National Coastal Assessment (NCA) and National Aquatic Resource Surveys (NARS) programs. Here we rep...

Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

NASA Astrophysics Data System (ADS)

Dongxue, Wu; Ping, Ma; Boting, Liu; Shuo, Zhang; Junxi, Wang; Jinmin, Li

2016-10-01

The effect of patterned sapphire substrate (PSS) on the top-surface (P-GaN-surface) and the bottom-surface (sapphire-surface) of the light output power (LOP) of GaN-based LEDs was investigated, in order to study the changes in reflection and transmission of the GaN-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of GaN-based LEDs, which are prepared on patterned sapphire substrates (PSS-LEDs). Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates (CSS-LEDs). A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-GaN interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency (LEE) can be further enhanced by integrating the method of PSS and flip-chip structure design. Project supported by the National High Technology Program of China (No. Y48A040000) and the National High Technology Program of China (No. Y48A040000).

A flexible scintillation light apparatus for rare events searches

NASA Astrophysics Data System (ADS)

Gironi, L.; Baldazzi, G.; Bonvicini, V.; Campana, R.; Capelli, S.; Evangelista, Y.; Fasoli, M.; Feroci, M.; Fuschino, F.; Labanti, C.; Marisaldi, M.; Previtali, E.; Riganese, L.; Rashevsky, A.; Sisti, M.; Vacchi, A.; Vedda, A.; Zampa, G.; Zampa, N.; Zuffa, M.

2016-05-01

FLARES (a Flexible scintillation Light Apparatus for Rare Event Searches) is a project for an innovative detector technology to be applied to rare event searches, and in particular to neutrinoless double beta decay experiments. Its novelty is the enhancement and optimization of the collection of the scintillation light emitted by ultra-pure crystals through the use of arrays of high performance silicon photodetectors cooled to 120 K. This would provide scintillation detectors with ~1% level energy resolution, with the advantages of a technology offering relatively simple low cost mass scalability and powerful background reduction handles, as requested by future neutrinoless double beta decay experimental programs.

Just-in-Time Teaching: A Tool for Enhancing Student Engagement in Advanced Foreign Language Learning

ERIC Educational Resources Information Center

Abreu, Laurel; Knouse, Stephanie

2014-01-01

Scholars have indicated a need for further research on effective pedagogical strategies designed for advanced foreign language courses in the postsecondary setting, especially in light of decreased enrollments at this level and the elimination of foreign language programs altogether in some institutions (Paesani & Allen, 2012). This article…

Green Light Synergistally Enhances Male Sweetpotato Weevil Response to Sex Pheromone

PubMed Central

McQuate, Grant T.

2014-01-01

Sweetpotato, commercially grown in over 100 countries, is one of the ten most important staple crops in the world. Sweetpotato weevil is a major pest of sweetpotato in most areas of cultivation, the feeding of which induces production in the sweetpotato root of extremely bitter tasting and toxic sesquiterpenes which can render the sweetpotato unfit for consumption. A significant step towards improved management of this weevil species was the identification of a female-produced sex pheromone [(Z)-3-dodecenyl (E)-2-butenoate] to which males are highly attracted. Reported here are results of research that documents a nearly 5-fold increase in male sweetpotato weevil catch in traps baited with this pheromone and a green light provided by a solar-powered, light-emitting diode (LED). The combination of olfactory and night-visible visual cues significantly enhanced trap effectiveness for this nighttime-active insect species. These results provide promise for improved sweetpotato weevil detection and suppression in mass trapping programs. PMID:24675727

The relationship between phytoplankton concentration and light attenuation in ocean waters

NASA Technical Reports Server (NTRS)

Phinney, David A.; Yentsch, Charles S.

1986-01-01

The accuracy of chlorophyll estimates by ocean color algorithms is affected by the variability of particulate attenuation; the presence of dissolved organic matter; and the nonlinear inverse relationship between the attenuation coefficient, K, and chlorophyll. Data collected during the Warm Core Rings Program were used to model the downwelling light field and determine the impact of these errors. A possible mechanism for the nonlinearity of K and chlorophyll is suggested; namely, that changing substrate from nitrate-nitrogen to ammonium causes enhanced blue absorption by photosynthetic phytoplankton in oligotrophic surface waters.

Modules to enhance smart lighting education

NASA Astrophysics Data System (ADS)

Bunch, Robert M.; Joenathan, Charles; Connor, Kenneth; Chouikha, Mohamed

2012-10-01

Over the past several years there has been a rapid advancement in solid state lighting applications brought on by the development of high efficiency light emitting diodes. Development of lighting devices, systems and products that meet the demands of the future lighting marketplace requires workers from many disciplines including engineers, scientists, designers and architects. The National Science Foundation has recognized this fact and established the Smart Lighting Engineering Research Center that promotes research leading to smart lighting systems, partners with industry to enhance innovation and educates a diverse, world-class workforce. The lead institution is Rensselaer Polytechnic Institute with core partners Boston University and The University of New Mexico. Outreach partners include Howard University, Morgan State University, and Rose-Hulman Institute of Technology. Because of the multidisciplinary nature of advanced smart lighting systems workers often have little or no formal education in basic optics, lighting and illumination. This paper describes the initial stages of the development of self-contained and universally applicable educational modules that target essential optics topics needed for lighting applications. The modules are intended to be easily incorporated into new and existing courses by a variety of educators and/or to be used in a series of stand-alone, asynchronous training exercises by new graduate students. The ultimate goal of this effort is to produce resources such as video lectures, video presentations of students-teaching-students, classroom activities, assessment tools, student research projects and laboratories integrated into learning modules. Sample modules and resources will be highlighted. Other outreach activities such as plans for coursework, undergraduate research, design projects, and high school enrichment programs will be discussed.

Reliability and validity enhancement: a treatment package for increasing fidelity of self-report.

PubMed

Bornstein, P H; Hamilton, S B; Miller, R K; Quevillon, R P; Spitzform, M

1977-07-01

This study investigated the effects of reliability and validity "enhancers" on fidelity of self-report data in an analogue therapy situation. Under the guise of a Concentration Skills Training Program, 57 Ss were assigned randomly to one of the following conditions: (a) Reliability Enhancement; (b) Truth Talk; (c) No Comment Control. Results indicated significant differences among groups (p less than .05). In addition, tests of multiple comparisons revealed that Reliability Enhancement was significantly different from Truth Talk in occurrences of unreliability (p less than .05). These findings are discussed in light of the increased reliance on self-report data in behavioral intervention, and recommendations are made for future research.

Materials and Designs for High-Efficacy LED Light Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibbetson, James; Gresback, Ryan

Cree, Inc. conducted a narrow-band downconverter (NBD) materials development and implementation program which will lead to warm-white LED light engines with enhanced efficacy via improved spectral efficiency with respect to the human eye response. New red (600-630nm) NBD materials could result in as much as a 20% improvement in warm-white efficacy at high color quality relative to conventional phosphor-based light sources. Key program innovations included: high quantum yield; narrow peak width; minimized component-level losses due to “cross-talk” and light scattering among red and yellow-green downconverters; and improved reliability to reach parity with conventional phosphors. NBD-enabled downconversion efficiency gains relative tomore » conventional phosphors yielded an end-of-project LED light engine efficacy of >160 lm/W at room temperature and 35 A/cm2, with a correlated color temperature (CCT) of ~3500K and >90 CRI (Color Rending Index). NBD-LED light engines exhibited equivalent luminous flux and color point maintenance at >1,000 hrs. of highly accelerated reliability testing as conventional phosphor LEDs. A demonstration luminaire utilizing an NBD-based LED light engine had a steady-state system efficacy of >150 lm/W at ~3500K and >90 CRI, which exceeded the 2014 DOE R&D Plan luminaire milestone for FY17 of >150 lm/W at just 80 CRI.« less

Dark Skies Rangers

NASA Astrophysics Data System (ADS)

Doran, Rosa

2015-08-01

Creating awareness about the importance of the protection of our dark skies is the main goal of the Dark Skies Rangers project, a joint effort from the NOAO and the Galileo Teacher Training Program. Hundreds of schools and thousands of students have been reached by this program. We will focus in particular on the experience being developed in Portugal where several municipalities have now received street light auditing produced by students with suggestions on how to enhance the energy efficiency of illumination of specific urban areas. In the International Year of Light we are investing our efforts in exporting the successful Portuguese experience to other countries. The recipe is simple: train teachers, engage students, foster the participation of local community and involve local authorities in the process. In this symposium we hope to draft the cookbook for the near future.

Magnetic field enhanced electroluminescence in organic light emitting diodes based on electron donor-acceptor exciplex blends

NASA Astrophysics Data System (ADS)

Baniya, Sangita; Basel, Tek; Sun, Dali; McLaughlin, Ryan; Vardeny, Zeev Valy

2016-03-01

A useful process for light harvesting from injected electron-hole pairs in organic light emitting diodes (OLED) is the transfer from triplet excitons (T) to singlet excitons (S) via reverse intersystem crossing (RISC). This process adds a delayed electro-luminescence (EL) emission component that is known as thermally activated delayed fluorescence (TADF). We have studied electron donor (D)/acceptor(A) blends that form an exciplex manifold in which the energy difference, ΔEST between the lowest singlet (S1) and triplet (T1) levels is relatively small (<100 meV), and thus allows RISC at ambient temperature. We found that the EL emission in OLED based on the exciplex blend is enhanced up to 40% by applying a relatively weak magnetic field of 50 mT at ambient. Moreover the MEL response is activated with activation energy similar that of the EL emission. This suggests that the large magneto-EL originates from an additional spin-mixing channel between singlet and triplet states of the generated exciplexes, which is due to TADF. We will report on the MEL dependencies on the temperature, bias voltage, and D-A materials for optimum OLED performance. Supported by SAMSUNG Global Research Outreach (GRO) program, and also by the NSF-Material Science & Engineering Center (MRSEC) program at the University of Utah (DMR-1121252).

Digital radiography in general dental practice: a field study.

PubMed

Hellén-Halme, K; Nilsson, M; Petersson, A

2007-07-01

The aim of this study was to conduct a field study to survey the performance of digital radiography and how it was used by dentists in general dental practice. 19 general dental practitioners were visited at their clinics. Ambient light (illuminance) was measured in the rooms where the monitors were placed. Different technical display parameters were noted. Test images and two phantoms--one low-contrast phantom and one line-pair resolution phantom--were used to evaluate the digital system. How the dentists used the enhancement program was investigated by noting which functions were used. Average illuminance in the operating room was 668 lux (range 190-1250 lux). On radiographs of the low-contrast phantom taken at the clinic, the ability to observe the holes decreased as illuminance increased. On average, the "light percentage" initially set on the monitor had to be decreased by 17% and contrast by 10% to optimize the display of the test images. The general dental practitioners used the enhancement programs most often to alter brightness and contrast to obtain the subjectively best image. Large differences between the clinics were noted. Knowledge of how to handle digital equipment in general dental practice should be improved. A calibrated monitor of good quality should be a given priority, as should proper ambient light conditions. There is a need to develop standardized quality controls for digital dental radiography.

Monte Carlo modeling of spatially complex wrist tissue for the optimization of optical pulse oximeters

NASA Astrophysics Data System (ADS)

Robinson, Mitchell; Butcher, Ryan; Coté, Gerard L.

2017-02-01

Monte Carlo modeling of photon propagation has been used in the examination of particular areas of the body to further enhance the understanding of light propagation through tissue. This work seeks to improve upon the established simulation methods through more accurate representations of the simulated tissues in the wrist as well as the characteristics of the light source. The Monte Carlo simulation program was developed using Matlab. Generation of different tissue domains, such as muscle, vasculature, and bone, was performed in Solidworks, where each domain was saved as a separate .stl file that was read into the program. The light source was altered to give considerations to both viewing angle of the simulated LED as well as the nominal diameter of the source. It is believed that the use of these more accurate models generates results that more closely match those seen in-vivo, and can be used to better guide the design of optical wrist-worn measurement devices.

The Efficacy of a PD Program on Enhancing On-the-Job Teaching Skills

ERIC Educational Resources Information Center

Sidky, Gihan

2017-01-01

This study assessed the methods of teaching English course taught at the general diploma at the college of Graduate Studies in Education, Cairo University in light of English teachers' needs and expectations. The Methodology course was reconstructed using the premises of students centered teaching techniques and taking into consideration what is…

Increasing the efficiency of photon collection in LArTPCs: the ARAPUCA light trap

NASA Astrophysics Data System (ADS)

Cancelo, G.; Cavanna, F.; Escobar, C. O.; Kemp, E.; Machado, A. A.; Para, A.; Segreto, E.; Totani, D.; Warner, D.

2018-03-01

The Liquid Argon Time Projection Chambers (LArTPCs) are a choice for the next generation of large neutrino detectors due to their optimal performance in particle tracking and calorimetry. The detection of Argon scintillation light plays a crucial role in the event reconstruction as well as the time reference for non-beam physics such as supernovae neutrino detection and baryon number violation studies. In this contribution, we present the current R&D work on the ARAPUCA (Argon R&D Advanced Program at UNICAMP), a light trap device to enhance Ar scintillation light collection and thus the overall performance of LArTPCs. The ARAPUCA working principle is based on a suitable combination of dichroic filters and wavelength shifters to achieve a high efficiency in light collection. We discuss the operational principles, the last results of laboratory tests and the application of the ARAPUCA as the alternative photon detection system in the protoDUNE detector.

Increased phytochrome B alleviates density effects on tuber yield of field potato crops.

PubMed

Boccalandro, Hernán E; Ploschuk, Edmundo L; Yanovsky, Marcelo J; Sánchez, Rodolfo A; Gatz, Christiane; Casal, Jorge J

2003-12-01

The possibility that reduced photomorphogenic responses could increase field crop yield has been suggested often, but experimental support is still lacking. Here, we report that ectopic expression of the Arabidopsis PHYB (phytochrome B) gene, a photoreceptor involved in detecting red to far-red light ratio associated with plant density, can increase tuber yield in field-grown transgenic potato (Solanum tuberosum) crops. Surprisingly, this effect was larger at very high densities, despite the intense reduction in the red to far-red light ratios and the concomitant narrowed differences in active phytochrome B levels between wild type and transgenics at these densities. Increased PHYB expression not only altered the ability of plants to respond to light signals, but they also modified the light environment itself. This combination resulted in larger effects of enhanced PHYB expression on tuber number and crop photosynthesis at high planting densities. The PHYB transgenics showed higher maximum photosynthesis in leaves of all strata of the canopy, and this effect was largely due to increased leaf stomatal conductance. We propose that enhanced PHYB expression could be used in breeding programs to shift optimum planting densities to higher levels.

A Qualitative Evaluation of Engagement and Attrition in a Nurse Home Visiting Program: From the Participant and Provider Perspective.

PubMed

Beasley, Lana O; Ridings, Leigh E; Smith, Tyler J; Shields, Jennifer D; Silovsky, Jane F; Beasley, William; Bard, David

2018-05-01

Beginning parenting programs in the prenatal and early postnatal periods have a large potential for impact on later child and maternal outcomes. Home-based parenting programs, such as the Nurse Family Partnership (NFP), have been established to help address this need. Program reach and impact is dependent on successful engagement of expecting mothers with significant risks; however, NFP attrition rates remain high. The current study qualitatively examined engagement and attrition from the perspectives of NFP nurses and mothers in order to identify mechanisms that enhance service engagement. Semi-structured interviews were conducted in focus groups composed of either engaged (27 total mothers) or unengaged (15 total mothers) mothers from the NFP program. NFP nurses (25 total nurses) were recruited for individual semi-structured interviews. Results suggest that understanding engagement in the NFP program requires addressing both initial and sustained engagement. Themes associated with enhanced initial engagement include nurse characteristics (e.g., flexible, supportive, caring) and establishment of a solid nurse-family relationship founded on these characteristics. Factors impacting sustained engagement include nurse characteristics, provision of educational materials on child development, individualized services for families, and available family support. Identified barriers to completing services include competing demands and lack of support. Findings of this study have direct relevance for workforce planning, including hiring and training through integrating results regarding effective nurse characteristics. Additional program supports to enhance parent engagement may be implemented across home-based parenting programs in light of the current study's findings.

The potential impact of microgravity science and technology on education

NASA Technical Reports Server (NTRS)

Wargo, M. J.

1992-01-01

The development of educational support materials by NASA's Microgravity Science and Applications Division is discussed in the light of two programs. Descriptions of the inception and application possibilities are given for the Microgravity-Science Teacher's Guide and the program of Undergraduate Research Opportunities in Microgravity Science and Technology. The guide is intended to introduce students to the principles and research efforts related to microgravity, and the undergraduate program is intended to reinforce interest in the space program. The use of computers and electronic communications is shown to be an important catalyst for the educational efforts. It is suggested that student and teacher access to these programs be enhanced so that they can have a broader impact on the educational development of space-related knowledge.

Effect of Light-Activated Tooth Whitening on Color Change Relative to Color of Artificially Stained Teeth.

PubMed

Kwon, So Ran; Kurti, Steven R; Oyoyo, Udochukwu; Li, Yiming

2015-01-01

There is still controversy as to the efficacy of light activation used in tooth whitening. The purpose of this study was to evaluate the effect of light activation on tooth color change relative to the artificial dye color. Extracted human third molars (160) were randomly distributed into eight groups of 20 specimens each based on artificial staining and use of light activation. All groups received three 45-minute sessions of in-office whitening at 3-day intervals. Color measurements were performed with an intraoral spectrophotometer at baseline prior to staining (T0), after artificial staining (T1), 1-day--(T2), and 1-week--(T3) post-whitening. Color differences were calculated relative to after artificial staining color parameters (L*1, a*1, b*1) with the use of a software analysis program enabling synchronization of two images. Within the same staining groups, the light-activated samples exhibited a greater color change than their nonlight-activated counterparts. However, only in the case of the yellow-stained samples at 1-day post-whitening was there a significant difference between the nonlight-activated and light-activated groups (Tukey's post hoc multiple comparison test for pairwise comparisons, p < 0.05). Light activation is a valid method for enhancing the efficacy of tooth whitening with respect to overall color change and works best with yellow stains. Light activation is a valid method for enhancing the efficacy of tooth whitening with respect to overall color change and works best with yellow stains.

The Red Light Receptor Phytochrome B Directly Enhances Substrate-E3 Ligase Interactions to Attenuate Ethylene Responses.

PubMed

Shi, Hui; Shen, Xing; Liu, Renlu; Xue, Chang; Wei, Ning; Deng, Xing Wang; Zhong, Shangwei

2016-12-05

Plants germinating under subterranean darkness assume skotomorphogenesis, a developmental program strengthened by ethylene in response to mechanical pressure of soil. Upon reaching the surface, light triggers a dramatic developmental transition termed de-etiolation that requires immediate termination of ethylene responses. Here, we report that light activation of photoreceptor phyB results in rapid degradation of EIN3, the master transcription factor in the ethylene signaling pathway. As a result, light rapidly and efficiently represses ethylene actions. Specifically, phyB directly interacts with EIN3 in a light-dependent manner and also physically associates with F box protein EBFs. The light-activated association of phyB, EIN3, and EBF1/EBF2 proteins stimulates robust EIN3 degradation by SCF EBF1/EBF2 E3 ligases. We reveal that phyB manipulates substrate-E3 ligase interactions in a light-dependent manner, thus directly controlling the stability of EIN3. Our findings illustrate a mechanistic model of how plants transduce light information to immediately turn off ethylene signaling for de-etiolation initiation. Copyright © 2016 Elsevier Inc. All rights reserved.

Enhancements of Bayesian Blocks; Application to Large Light Curve Databases

NASA Technical Reports Server (NTRS)

Scargle, Jeff

2015-01-01

Bayesian Blocks are optimal piecewise linear representations (step function fits) of light-curves. The simple algorithm implementing this idea, using dynamic programming, has been extended to include more data modes and fitness metrics, multivariate analysis, and data on the circle (Studies in Astronomical Time Series Analysis. VI. Bayesian Block Representations, Scargle, Norris, Jackson and Chiang 2013, ApJ, 764, 167), as well as new results on background subtraction and refinement of the procedure for precise timing of transient events in sparse data. Example demonstrations will include exploratory analysis of the Kepler light curve archive in a search for "star-tickling" signals from extraterrestrial civilizations. (The Cepheid Galactic Internet, Learned, Kudritzki, Pakvasa1, and Zee, 2008, arXiv: 0809.0339; Walkowicz et al., in progress).

Smart Image Enhancement Process

NASA Technical Reports Server (NTRS)

Jobson, Daniel J. (Inventor); Rahman, Zia-ur (Inventor); Woodell, Glenn A. (Inventor)

2012-01-01

Contrast and lightness measures are used to first classify the image as being one of non-turbid and turbid. If turbid, the original image is enhanced to generate a first enhanced image. If non-turbid, the original image is classified in terms of a merged contrast/lightness score based on the contrast and lightness measures. The non-turbid image is enhanced to generate a second enhanced image when a poor contrast/lightness score is associated therewith. When the second enhanced image has a poor contrast/lightness score associated therewith, this image is enhanced to generate a third enhanced image. A sharpness measure is computed for one image that is selected from (i) the non-turbid image, (ii) the first enhanced image, (iii) the second enhanced image when a good contrast/lightness score is associated therewith, and (iv) the third enhanced image. If the selected image is not-sharp, it is sharpened to generate a sharpened image. The final image is selected from the selected image and the sharpened image.

General method to evaluate substrate surface modification techniques for light extraction enhancement of organic light emitting diodes

NASA Astrophysics Data System (ADS)

Krummacher, B. C.; Mathai, M. K.; Choong, V.; Choulis, S. A.; So, F.; Winnacker, A.

2006-09-01

The external light output of organic light emitting diodes (OLEDs) can be increased by modifying the light emitting surface. The apparent light extraction enhancement is given by the ratio between the efficiency of the unmodified device and the efficiency of the modified device. This apparent light extraction enhancement is dependent on the OLED architecture itself and is not the correct value to judge the effectiveness of a technique to enhance light outcoupling due to substrate surface modification. We propose a general method to evaluate substrate surface modification techniques for light extraction enhancement of OLEDs independent from the device architecture. This method is experimentally demonstrated using green electrophosphorescent OLEDs with different device architectures. The substrate surface of these OLEDs was modified by applying a prismatic film to increase light outcoupling from the device stack. It was demonstrated that the conventionally measured apparent light extraction enhancement by means of the prismatic film does not reflect the actual performance of the light outcoupling technique. Rather, by comparing the light extracted out of the prismatic film to that generated in the OLED layers and coupled into the substrate (before the substrate/air interface), a more accurate evaluation of light outcoupling enhancement can be achieved. Furthermore we show that substrate surface modification can change the output spectrum of a broad band emitting OLED.

Visibility enhancement in two-dimensional lensless ghost imaging with true thermal light

NASA Astrophysics Data System (ADS)

Chen, Xi-Hao; Yan, Ling; Wu, Wei; Meng, Shao-Ying; Wu, Ling-An; Sun, Zhi-Bin; Wang, Chao; Zhai, Guang-Jie

2017-06-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 11204117, 11304007, and 60907031), the China Postdoctoral Science Foundation (Grant No. 2013M540146), the Fund from the Education Department of Liaoning Province, China (Grant No. L2012001), and the National Hi-Tech Research and Development Program of China (Grant No. 2013AA122902).

Plasma Radiation Source Development Program

DTIC Science & Technology

2006-03-01

shell mass distributions perform belter than thin shells. The dual plenum, double shell load has unique diagnostic features that enhance our...as implosion time increases. 13. SUBJECT TERMS Zpinch x-ray diagnostics Rayleigh-Taylor instability pulsed-power x-ray spectroscopy supersonic...feature permits some very useful diagnostics that shed light on critical details of the implosion process. See Section 3 for details. We have

Light output improvement of GaN-based light-emitting diodes grown on Si (111) by a via-thin-film structure

NASA Astrophysics Data System (ADS)

Li, Zengcheng; Feng, Bo; Deng, Biao; Liu, Legong; Huang, Yingnan; Feng, Meixin; Zhou, Yu; Zhao, Hanmin; Sun, Qian; Wang, Huaibing; Yang, Xiaoli; Yang, Hui

2018-04-01

This work reports the fabrication of via-thin-film light-emitting diode (via-TF-LED) to improve the light output power (LOP) of blue/white GaN-based LEDs grown on Si (111) substrates. The as-fabricated via-TF-LEDs were featured with a roughened n-GaN surface and the p-GaN surface bonded to a wafer carrier with a silver-based reflective electrode, together with an array of embedded n-type via pillar metal contact from the p-GaN surface etched through the multiple-quantum-wells (MQWs) into the n-GaN layer. When operated at 350 mA, the via-TF-LED gave an enhanced blue LOP by 7.8% and over 3.5 times as compared to the vertical thin-film LED (TF-LED) and the conventional lateral structure LED (LS-LED). After covering with yellow phosphor that converts some blue photons into yellow light, the via-TF-LED emitted an enhanced white luminous flux by 13.5% and over 5 times, as compared with the white TF-LED and the white LS-LED, respectively. The significant LOP improvement of the via-TF-LED was attributed to the elimination of light absorption by the Si (111) epitaxial substrate and the finger-like n-electrodes on the roughened emitting surface. Project supported by the National Key R&D Program (Nos. 2016YFB0400100, 2016YFB0400104), the National Natural Science Foundation of China (Nos. 61534007, 61404156, 61522407, 61604168, 61775230), the Key Frontier Scientific Research Program of the Chinese Academy of Sciences (No. QYZDB-SSW-JSC014), the Science and Technology Service Network Initiative of the Chinese Academy of Sciences, the Key R&D Program of Jiangsu Province (No. BE2017079), the Natural Science Foundation of Jiangsu Province (No. BK20160401), and the China Postdoctoral Science Foundation (No. 2016M591944). This work was also supported by the Open Fund of the State Key Laboratory of Luminescence and Applications (No. SKLA-2016-01), the Open Fund of the State Key Laboratory on Integrated Optoelectronics (Nos. IOSKL2016KF04, IOSKL2016KF07), and the Seed Fund from SINANO, CAS (No. Y5AAQ51001).

Novel Organic Phototransistor-Based Nonvolatile Memory Integrated with UV-Sensing/Green-Emissive Aggregation Enhanced Emission (AEE)-Active Aromatic Polyamide Electret Layer.

PubMed

Cheng, Shun-Wen; Han, Ting; Huang, Teng-Yung; Chang Chien, Yu-Hsin; Liu, Cheng-Liang; Tang, Ben Zhong; Liou, Guey-Sheng

2018-05-30

A novel aggregation enhanced emission (AEE)-active polyamide TPA-CN-TPE with a high photoluminesence characteristic was successfully synthesized by the direct polymerization of 4-cyanotriphenyl diamine (TPA-CN) and tetraphenylethene (TPE)-containing dicarboxylic acid. The obtained luminescent polyamide plays a significant role as the polymer electret layer in organic field-effect transistors (OFETs)-type memory. The strong green emission of TPA-CN-TPE under ultraviolet (UV) irradiation can be directly absorbed by the pentacene channel, displaying a light-induced programming and voltage-driven erasing organic phototransistor-based nonvolatile memory. Memory window can be effectively manipulated between the programming and erasing states by applying UV light illumination and electrical field, respectively. The photoinduced memory behavior can be maintained for over 10 4 s between these two states with an on/off ratio of 10 4 , and the memory switching can be steadily operated for many cycles. With high photoresponsivity ( R) and photosensitivity ( S), this organic phototransistor integrated with AEE-active polyamide electret layer could serve as an excellent candidate for UV photodetectors in optical applications. For comparison, an AEE-inactive aromatic polyimide TPA-PIS electret with much weaker solid-state emission was also applied in the same OFETs device architecture, but this device did not show any UV-sensitive and UV-induced memory characteristics, which further confirmed the significance of the light-emitting capability of the electret layer.

Enhanced automated spiral bevel gear inspection

NASA Technical Reports Server (NTRS)

Frint, Harold K.; Glasow, Warren

1992-01-01

Presented here are the results of a manufacturing and technology program to define, develop, and evaluate an enhanced inspection system for spiral bevel gears. The method uses a multi-axis coordinate measuring machine which maps the working surface of the tooth and compares it with nominal reference values stored in the machine's computer. The enhanced technique features a means for automatically calculating corrective grinding machine settings, involving both first and second order changes, to control the tooth profile to within specified tolerance limits. This enhanced method eliminates the subjective decision making involved in the tooth patterning method, still in use today, which compares contract patterns obtained when the gear is set to run under light load in a rolling test machine. It produces a higher quality gear with significant inspection time and cost savings.

To enhance light extraction of OLED devices by multi-optic layers including a micro lens array

NASA Astrophysics Data System (ADS)

Chiu, Chuang-Hung; Chien, Chao-Heng; Kuo, Yu-Xaong; Lee, Jen-Chi

2014-10-01

In recent years, OLED has advantages including that larger light area, thinner thickness, excellent light uniformity, and can be as a flexible light source. Many display panel and lighting have been started to use the OLED due to OLED without back light system, thus how to make and employ light extracting layer could be important issue to enhance OLED brightness. The purpose of this study is to enhance the light extraction efficiency and light emitting area of OLED, so the micro lens array and the prism reflection layer were provided to enhance the surface light extracting efficiency of OLD. Finally the prism layer and diffusing layer were used to increase the uniformity of emitting area of OLED, which the efficiency of 31% increasing to compare with the OLED without light extracting film.

Continuous background light significantly increases flashing-light enhancement of photosynthesis and growth of microalgae.

PubMed

Abu-Ghosh, Said; Fixler, Dror; Dubinsky, Zvy; Iluz, David

2015-01-01

Under specific conditions, flashing light enhances the photosynthesis rate in comparison to continuous illumination. Here we show that a combination of flashing light and continuous background light with the same integrated photon dose as continuous or flashing light alone can be used to significantly enhance photosynthesis and increase microalgae growth. To test this hypothesis, the green microalga Dunaliella salina was exposed to three different light regimes: continuous light, flashing light, and concomitant application of both. Algal growth was compared under three different integrated light quantities; low, intermediate, and moderately high. Under the combined light regime, there was a substantial increase in all algal growth parameters, with an enhanced photosynthesis rate, within 3days. Our strategy demonstrates a hitherto undescribed significant increase in photosynthesis and algal growth rates, which is beyond the increase by flashing light alone. Copyright © 2015 Elsevier Ltd. All rights reserved.

Increasing the efficiency of photon collection in LArTPCs: the ARAPUCA light trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cancelo, G.; Cavanna, F.; Escobar, C. O.

The Liquid Argon Time Projection Chambers (LArTPCs) are a choice for the next generation of large neutrino detectors due to their optimal performance in particle tracking and calorimetry. The detection of Argon scintillation light plays a crucial role in the event reconstruction as well as the time reference for non-beam physics such as supernovae neutrino detection and baryon number violation studies. Here in this contribution, we present the current R&D work on the ARAPUCA (Argon R&D Advanced Program at UNICAMP), a light trap device to enhance Ar scintillation light collection and thus the overall performance of LArTPCs. The ARAPUCA workingmore » principle is based on a suitable combination of dichroic filters and wavelength shifters to achieve a high efficiency in light collection. We discuss the operational principles, the last results of laboratory tests and the application of the ARAPUCA as the alternative photon detection system in the protoDUNE detector.« less

Increasing the efficiency of photon collection in LArTPCs: the ARAPUCA light trap

DOE PAGES

Cancelo, G.; Cavanna, F.; Escobar, C. O.; ...

2018-03-26

The Liquid Argon Time Projection Chambers (LArTPCs) are a choice for the next generation of large neutrino detectors due to their optimal performance in particle tracking and calorimetry. The detection of Argon scintillation light plays a crucial role in the event reconstruction as well as the time reference for non-beam physics such as supernovae neutrino detection and baryon number violation studies. Here in this contribution, we present the current R&D work on the ARAPUCA (Argon R&D Advanced Program at UNICAMP), a light trap device to enhance Ar scintillation light collection and thus the overall performance of LArTPCs. The ARAPUCA workingmore » principle is based on a suitable combination of dichroic filters and wavelength shifters to achieve a high efficiency in light collection. We discuss the operational principles, the last results of laboratory tests and the application of the ARAPUCA as the alternative photon detection system in the protoDUNE detector.« less

Project SunSHINE: A Student Based Solar Research Program

NASA Astrophysics Data System (ADS)

Donahue, R.

2000-12-01

Eastchester Middle School (NY) is currently conducting an ongoing, interdisciplinary solar research program entitled Project SunSHINE, for Students Help Investigate Nature in Eastchester. Students are to determine how ultraviolet and visible light levels vary throughout the year at the school's geographic location, and to ascertain if any measured variations correlate to daily weather conditions or sunspot activity. The educational goal is to provide students the opportunity to conduct original and meaningful scientific research, while learning to work collaboratively with peers and teachers in accordance with national mathematics, science and technology standards. Project SunSHINE requires the student researchers to employ a number of technologies to collect and analyze data, including light sensors, astronomical imaging software, an onsite AirWatch Weather Station, Internet access to retrieve daily solar images from the National Solar Observatory's Kitt Peak Vacuum Telescope, and two wide field telescopes for live sunspot observations. The program has been integrated into the science, mathematics, health and computer technology classes. Solar and weather datasets are emailed weekly to physicist Dr. Gil Yanow of the Jet Propulsion Laboratory for inclusion in his global study of light levels. Dr. Yanow credited the Project SunSHINE student researchers last year for the discovery of an inverse relationship between relative humidity and ultraviolet light levels. The Journal News Golden Apple Awards named Project SunSHINE the 1999 New York Wired Applied Technology Award winner. This honor recognizes the year's outstanding educational technology program at both the elementary and secondary level, and included a grant of \\$20,000 to the research program. Teacher training and image processing software for Project SunSHINE has been supplied by The Use of Astronomy in Research Based Science Education (RBSE), a Teacher Enhancement Program funded by the National Science Foundation and conducted at the facilities of the National Optical Astronomy Observatory in Tucson, Arizona.

Technical and Economic Aspects of Designing an Efficient Room Air-Conditioner Program in India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abhyankar, Nikit; Shah, Nihar; Phadke, Amol

Several studies have projected a massive increase in the demand for air conditioners (ACs) over the next two decades in India. By 2030, room ACs could add 140 GW to the peak load, equivalent to over 30% of the total projected peak load. Therefore, there is significant interest among policymakers, regulators, and utilities in managing room AC demand by enhancing energy efficiency. Building on the historical success of the Indian Bureau of Energy Efficiency’s star-labeling program, Energy Efficiency Services Limited recently announced a program to accelerate the sale of efficient room ACs using bulk procurement, similar to their successful UJALAmore » light-emitting diode (LED) bulk procurement program. This report discusses some of the key considerations in designing a bulk procurement or financial incentive program for enhancing room AC efficiency in India. We draw upon our previous research to demonstrate the overall technical potential and price impact of room AC efficiency improvement and its technical feasibility in India. We also discuss the importance of using low global warming potential (GWP) refrigerants and smart AC equipment that is demand response (DR) ready.« less

Toward Enhancing OpenMP's Work-Sharing Directives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, B M; Huang, L; Jin, H

2006-05-17

OpenMP provides a portable programming interface for shared memory parallel computers (SMPs). Although this interface has proven successful for small SMPs, it requires greater flexibility in light of the steadily growing size of individual SMPs and the recent advent of multithreaded chips. In this paper, we describe two application development experiences that exposed these expressivity problems in the current OpenMP specification. We then propose mechanisms to overcome these limitations, including thread subteams and thread topologies. Thus, we identify language features that improve OpenMP application performance on emerging and large-scale platforms while preserving ease of programming.

Department of Defense Enhanced Particulate Matter Surveillance Program (EPMSP)

DTIC Science & Technology

2008-02-01

on Teflon® membrane, 23,807 on quartz fiber, and several million single particle analyses on Nuclepore® filters. Analytical results were...Nuclepore® filters, the sampling period was two hours, so as to provide lightly loaded filters with dispersed single particles, as required for CCSEM...membrane, 23,807 on quartz fiber, and several million single particle analyses on Nuclepore®. All results, together with summary tables and more than

Music enrichment programs improve the neural encoding of speech in at-risk children.

PubMed

Kraus, Nina; Slater, Jessica; Thompson, Elaine C; Hornickel, Jane; Strait, Dana L; Nicol, Trent; White-Schwoch, Travis

2014-09-03

Musicians are often reported to have enhanced neurophysiological functions, especially in the auditory system. Musical training is thought to improve nervous system function by focusing attention on meaningful acoustic cues, and these improvements in auditory processing cascade to language and cognitive skills. Correlational studies have reported musician enhancements in a variety of populations across the life span. In light of these reports, educators are considering the potential for co-curricular music programs to provide auditory-cognitive enrichment to children during critical developmental years. To date, however, no studies have evaluated biological changes following participation in existing, successful music education programs. We used a randomized control design to investigate whether community music participation induces a tangible change in auditory processing. The community music training was a longstanding and successful program that provides free music instruction to children from underserved backgrounds who stand at high risk for learning and social problems. Children who completed 2 years of music training had a stronger neurophysiological distinction of stop consonants, a neural mechanism linked to reading and language skills. One year of training was insufficient to elicit changes in nervous system function; beyond 1 year, however, greater amounts of instrumental music training were associated with larger gains in neural processing. We therefore provide the first direct evidence that community music programs enhance the neural processing of speech in at-risk children, suggesting that active and repeated engagement with sound changes neural function. Copyright © 2014 the authors 0270-6474/14/3411913-06$15.00/0.

Effective light absorption and its enhancement factor for silicon nanowire-based solar cell.

PubMed

Duan, Zhiqiang; Li, Meicheng; Mwenya, Trevor; Fu, Pengfei; Li, Yingfeng; Song, Dandan

2016-01-01

Although nanowire (NW) antireflection coating can enhance light trapping capability, which is generally used in crystal silicon (CS) based solar cells, whether it can improve light absorption in the CS body depends on the NW geometrical shape and their geometrical parameters. In order to conveniently compare with the bare silicon, two enhancement factors E(T) and E(A) are defined and introduced to quantitatively evaluate the efficient light trapping capability of NW antireflective layer and the effective light absorption capability of CS body. Five different shapes (cylindrical, truncated conical, convex conical, conical, and concave conical) of silicon NW arrays arranged in a square are studied, and the theoretical results indicate that excellent light trapping does not mean more light can be absorbed in the CS body. The convex conical NW has the best light trapping, but the concave conical NW has the best effective light absorption. Furthermore, if the cross section of silicon NW is changed into a square, both light trapping and effective light absorption are enhanced, and the Eiffel Tower shaped NW arrays have optimal effective light absorption.

Multi-wavelength optical measurement to enhance thermal/optical analysis for carbonaceous aerosol

NASA Astrophysics Data System (ADS)

Chen, L.-W. A.; Chow, J. C.; Wang, X. L.; Robles, J. A.; Sumlin, B. J.; Lowenthal, D. H.; Zimmermann, R.; Watson, J. G.

2015-01-01

A thermal/optical carbon analyzer equipped with seven-wavelength light source/detector (405-980 nm) for monitoring spectral reflectance (R) and transmittance (T) of filter samples allowed "thermal spectral analysis (TSA)" and wavelength (λ)-dependent organic-carbon (OC)-elemental-carbon (EC) measurements. Optical sensing was calibrated with transfer standards traceable to absolute R and T measurements, adjusted for loading effects to report spectral light absorption (as absorption optical depth (τa, λ)), and verified using diesel exhaust samples. Tests on ambient and source samples show OC and EC concentrations equivalent to those from conventional carbon analysis when based on the same wavelength (~ 635 nm) for pyrolysis adjustment. TSA provides additional information that evaluates black-carbon (BC) and brown-carbon (BrC) contributions and their optical properties in the near infrared to the near ultraviolet parts of the solar spectrum. The enhanced carbon analyzer can add value to current aerosol monitoring programs and provide insight into more accurate OC and EC measurements for climate, visibility, or health studies.

Multi-wavelength optical measurement to enhance thermal/optical analysis for carbonaceous aerosol

NASA Astrophysics Data System (ADS)

Chen, L.-W. A.; Chow, J. C.; Wang, X. L.; Robles, J. A.; Sumlin, B.; Lowenthal, D. H.; Zimmermann, R.; Watson, J. G.

2014-09-01

A thermal/optical carbon analyzer equipped with seven-wavelength light source/detector (405-980 nm) for monitoring spectral reflectance (R) and transmittance (T) of filter samples allows "thermal spectral analysis (TSA)" and wavelength (λ)-dependent organic carbon (OC)-elemental carbon (EC) measurements. Optical sensing is calibrated with transfer standards traceable to absolute R and T measurements and adjusted for loading effects to determine spectral light absorption (as absorption optical depth [τa, λ]) using diesel exhaust samples as a reference. Tests on ambient and source samples show OC and EC concentrations equivalent to those from conventional carbon analysis when based on the same wavelength (~635 nm) for pyrolysis adjustment. TSA provides additional information that evaluates black carbon (BC) and brown carbon (BrC) contributions and their optical properties in the near-IR to the near-UV parts of the solar spectrum. The enhanced carbon analyzer can add value to current aerosol monitoring programs and provide insight into more accurate OC and EC measurements for climate, visibility, or health studies.

Enhanced light output from a nitride-based power chip of green light-emitting diodes with nano-rough surface using nanoimprint lithography.

PubMed

Huang, H W; Lin, C H; Yu, C C; Lee, B D; Chiu, C H; Lai, C F; Kuo, H C; Leung, K M; Lu, T C; Wang, S C

2008-05-07

Enhanced light extraction from a GaN-based power chip (PC) of green light-emitting diodes (LEDs) with a rough p-GaN surface using nanoimprint lithography is presented. At a driving current of 350 mA and with a chip size of 1 mm × 1 mm packaged on transistor outline (TO)-cans, the light output power of the green PC LEDs with nano-rough p-GaN surface is enhanced by 48% when compared with the same device without a rough p-GaN surface. In addition, by examining the radiation patterns, the green PC LED with nano-rough p-GaN surface shows stronger light extraction with a wider view angle. These results offer promising potential to enhance the light output powers of commercial light-emitting devices by using the technique of nanoimprint lithography under suitable nanopattern design.

Systems Engineering Design Via Experimental Operation Research: Complex Organizational Metric for Programmatic Risk Environments (COMPRE)

NASA Technical Reports Server (NTRS)

Mog, Robert A.

1999-01-01

Unique and innovative graph theory, neural network, organizational modeling, and genetic algorithms are applied to the design and evolution of programmatic and organizational architectures. Graph theory representations of programs and organizations increase modeling capabilities and flexibility, while illuminating preferable programmatic/organizational design features. Treating programs and organizations as neural networks results in better system synthesis, and more robust data modeling. Organizational modeling using covariance structures enhances the determination of organizational risk factors. Genetic algorithms improve programmatic evolution characteristics, while shedding light on rulebase requirements for achieving specified technological readiness levels, given budget and schedule resources. This program of research improves the robustness and verifiability of systems synthesis tools, including the Complex Organizational Metric for Programmatic Risk Environments (COMPRE).

Digital video technology and production 101: lights, camera, action.

PubMed

Elliot, Diane L; Goldberg, Linn; Goldberg, Michael J

2014-01-01

Videos are powerful tools for enhancing the reach and effectiveness of health promotion programs. They can be used for program promotion and recruitment, for training program implementation staff/volunteers, and as elements of an intervention. Although certain brief videos may be produced without technical assistance, others often require collaboration and contracting with professional videographers. To get practitioners started and to facilitate interactions with professional videographers, this Tool includes a guide to the jargon of video production and suggestions for how to integrate videos into health education and promotion work. For each type of video, production principles and issues to consider when working with a professional videographer are provided. The Tool also includes links to examples in each category of video applications to health promotion.

Improved performance of near UV light-emitting diodes with a composition-graded p-AlGaN irregular sawtooth electron-blocking layer

NASA Astrophysics Data System (ADS)

Qin, Ping; Song, Wei-Dong; Hu, Wen-Xiao; Zhang, Yuan-Wen; Zhang, Chong-Zhen; Wang, Ru-Peng; Zhao, Liang-Liang; Xia, Chao; Yuan, Song-Yang; Yin, Yi-an; Li, Shu-Ti; Su, Shi-Chen

2016-08-01

We investigate the performances of the near-ultraviolet (about 350 nm-360 nm) light-emitting diodes (LEDs) each with specifically designed irregular sawtooth electron blocking layer (EBL) by using the APSYS simulation program. The internal quantum efficiencies (IQEs), light output powers, carrier concentrations in the quantum wells, energy-band diagrams, and electrostatic fields are analyzed carefully. The results indicate that the LEDs with composition-graded p-Al x Ga1-x N irregular sawtooth EBLs have better performances than their counterparts with stationary component p-AlGaN EBLs. The improvements can be attributed to the improved polarization field in EBL and active region as well as the alleviation of band bending in the EBL/p-AlGaN interface, which results in less electron leakage and better hole injection efficiency, thus reducing efficiency droop and enhancing the radiative recombination rate. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474105 and 51172079), the Science and Technology Program of Guangdong Province, China (Grant Nos. 2015B090903078 and 2015B010105011), the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT13064), the Science and Technology Project of Guangzhou City, China (Grant No. 201607010246), and the Science and Technology Planning Project of Guangdong Province, China (Grant No. 2015A010105025).

Light management in perovskite solar cells and organic LEDs with microlens arrays

DOE PAGES

Peer, Akshit; Biswas, Rana; Park, Joong -Mok; ...

2017-04-28

Here, we demonstrate enhanced absorption in solar cells and enhanced light emission in OLEDs by light interaction with a periodically structured microlens array. We simulate n-i-p perovskite solar cells with a microlens at the air-glass interface, with rigorous scattering matrix simulations. The microlens focuses light in nanoscale regions within the absorber layer enhancing the solar cell. Optimal period of ~700 nm and microlens height of ~800-1000 nm, provides absorption (photocurrent) enhancement of 6% (6.3%). An external polymer microlens array on the air-glass side of the OLED generates experimental and theoretical enhancements >100%, by outcoupling trapped modes in the glass substrate.

The National Heart, Lung, and Blood Institute Small Business Program

PubMed Central

Marek, Kurt W.

2016-01-01

SUMMARY Small companies working to develop products in the cardiovascular space face numerous challenges, from regulatory, intellectual property, and reimbursement barriers to securing funds to keep the lights on and reach the next development milestone. Most small companies that spin out from universities have the scientific knowledge, but product development expertise and business acumen are also needed to be successful. Other challenges include reduced interest in early stage technologies (Pharma & Biotech 2015 in Review, EP Vantage) and limited deal flow for cardiovascular products (Gormley B., Wall Street Journal, September 15, 2014). The NHLBI small business program is a comprehensive ecosystem designed to address these critical challenges and to provide resources and expertise to assist early stage companies developing cardiovascular and other products within the institute’s mission. This article describes steps that NHLBI has taken to enhance our small business program to more effectively translate basic discoveries into commercial products to benefit patients and public health, including enhancing internal expertise and developing non-financial resources to assist small businesses as they develop their products and seek private sector investment and partnership. PMID:28580435

The National Heart, Lung, and Blood Institute Small Business Program: A Comprehensive Ecosystem for Biomedical Product Development.

PubMed

Marek, Kurt W

2016-12-01

Small companies working to develop products in the cardiovascular space face numerous challenges, from regulatory, intellectual property, and reimbursement barriers to securing funds to keep the lights on and reach the next development milestone. Most small companies that spin out from universities have the scientific knowledge, but product development expertise and business acumen are also needed to be successful. Other challenges include reduced interest in early stage technologies (Pharma & Biotech 2015 in Review, EP Vantage) and limited deal flow for cardiovascular products (Gormley B., Wall Street Journal, September 15, 2014). The NHLBI small business program is a comprehensive ecosystem designed to address these critical challenges and to provide resources and expertise to assist early stage companies developing cardiovascular and other products within the institute's mission. This article describes steps that NHLBI has taken to enhance our small business program to more effectively translate basic discoveries into commercial products to benefit patients and public health, including enhancing internal expertise and developing non-financial resources to assist small businesses as they develop their products and seek private sector investment and partnership.

Light-extraction enhancement for light-emitting diodes: a firefly-inspired structure refined by the genetic algorithm

NASA Astrophysics Data System (ADS)

Bay, Annick; Mayer, Alexandre

2014-09-01

The efficiency of light-emitting diodes (LED) has increased significantly over the past few years, but the overall efficiency is still limited by total internal reflections due to the high dielectric-constant contrast between the incident and emergent media. The bioluminescent organ of fireflies gave incentive for light-extraction enhance-ment studies. A specific factory-roof shaped structure was shown, by means of light-propagation simulations and measurements, to enhance light extraction significantly. In order to achieve a similar effect for light-emitting diodes, the structure needs to be adapted to the specific set-up of LEDs. In this context simulations were carried out to determine the best geometrical parameters. In the present work, the search for a geometry that maximizes the extraction of light has been conducted by using a genetic algorithm. The idealized structure considered previously was generalized to a broader variety of shapes. The genetic algorithm makes it possible to search simultaneously over a wider range of parameters. It is also significantly less time-consuming than the previous approach that was based on a systematic scan on parameters. The results of the genetic algorithm show that (1) the calculations can be performed in a smaller amount of time and (2) the light extraction can be enhanced even more significantly by using optimal parameters determined by the genetic algorithm for the generalized structure. The combination of the genetic algorithm with the Rigorous Coupled Waves Analysis method constitutes a strong simulation tool, which provides us with adapted designs for enhancing light extraction from light-emitting diodes.

Lawrence Berkeley Laboratory/University of California lighting program overview

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berman, S.

1981-12-01

The objective of the Lighting Program is to assist and work in concert with the lighting community (composed of manufacturers, designers, and users) to achieve a more efficient lighting economy. To implement its objectives, the Lighting Program has been divided into three major categories: technical engineering, buildings applications, and human impacts (impacts on health and vision). The technical program aims to undertake research and development projects that are both long-range and high-risk and which the lighting industry has little interest in pursuing on its own, but from which significant benefits could accrue to both the public and the industry. Themore » building applications program studies the effects that introducing daylighting in commercial buildings has on lighting and cooling electrical energy requirements as well as on peak demand. This program also examines optimization strategies for integrating energy-efficient design, lighting hardware, daylighting, and overall building energy requirements. The impacts program examines relationships between the user and the physical lighting environment, in particular how new energy-efficient technologies relate to human productivity and health. These efforts are interdisciplinary, involving engineering, optometry, and medicine. The program facilities are described and the personnel in the program is identified.« less

Tip-enhanced Raman spectroscopy and near-field polarization

NASA Astrophysics Data System (ADS)

Saito, Yuika; Mino, Toshihiro; Verma, Prabhat

2015-12-01

Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for High-resolution Raman spectroscopy. In this method, a metal coated nano-tip acts as a plasmonic antenna to enhance the originally weak Raman scattering from a nanometric volume of a sample. The technique enables to detect Raman scattering light from nano-scale area and also enhance the light intensity with combination of near-filed light and localized surface plasmon generated at a metallized tip apex. Nowadays TERS is used to investigate various nano-scale samples, for examples, carbon nanotubes, graphenes DNA and biomaterials. As the TERS developed, there is high demand to investigate the properties of near-field light e.g. polarization properties. We have analyzed the polarization properties of near-field light in TERS and successfully realized the quantitative nano-imaging by visible light.

Spatial and Angular Resolution Enhancement of Light Fields Using Convolutional Neural Networks

NASA Astrophysics Data System (ADS)

Gul, M. Shahzeb Khan; Gunturk, Bahadir K.

2018-05-01

Light field imaging extends the traditional photography by capturing both spatial and angular distribution of light, which enables new capabilities, including post-capture refocusing, post-capture aperture control, and depth estimation from a single shot. Micro-lens array (MLA) based light field cameras offer a cost-effective approach to capture light field. A major drawback of MLA based light field cameras is low spatial resolution, which is due to the fact that a single image sensor is shared to capture both spatial and angular information. In this paper, we present a learning based light field enhancement approach. Both spatial and angular resolution of captured light field is enhanced using convolutional neural networks. The proposed method is tested with real light field data captured with a Lytro light field camera, clearly demonstrating spatial and angular resolution improvement.

Spatial and Angular Resolution Enhancement of Light Fields Using Convolutional Neural Networks.

PubMed

Gul, M Shahzeb Khan; Gunturk, Bahadir K

2018-05-01

Light field imaging extends the traditional photography by capturing both spatial and angular distribution of light, which enables new capabilities, including post-capture refocusing, post-capture aperture control, and depth estimation from a single shot. Micro-lens array (MLA) based light field cameras offer a cost-effective approach to capture light field. A major drawback of MLA based light field cameras is low spatial resolution, which is due to the fact that a single image sensor is shared to capture both spatial and angular information. In this paper, we present a learning based light field enhancement approach. Both spatial and angular resolution of captured light field is enhanced using convolutional neural networks. The proposed method is tested with real light field data captured with a Lytro light field camera, clearly demonstrating spatial and angular resolution improvement.

Magnetically modulated electroluminescence from hybrid organic/inorganic light-emitting diodes based on electron donor-acceptor exciplex blends

NASA Astrophysics Data System (ADS)

Pang, Zhiyong; Baniya, Sangita; Zhang, Chuang; Sun, Dali; Vardeny, Z. Valy

2016-03-01

We report room temperature magnetically modulated electroluminescence from a hybrid organic/inorganic light-emitting diode (h-OLED), in which an inorganic magnetic tunnel junction (MTJ) with large room temperature magnetoresistance is coupled to an N,N,N ',N '-Tetrakis(4-methoxyphenyl)benzidine (MeO-TPD): tris-[3-(3-pyridyl)mesityl]borane (3TPYMB) [D-A] based OLED that shows thermally activated delayed luminescence. The exciplex-based OLED provides two spin-mixing channels: upper energy channel of polaron pairs and lower energy channel of exciplexes. In operation, the large resistance mismatch between the MTJ and OLED components is suppressed due to the non-linear I-V characteristic of the OLED. This leads to enhanced giant magneto-electroluminescence (MEL) at room temperature. We measured MEL of ~ 75% at ambient conditions. Supported by SAMSUNG Global Research Outreach (GRO) program, and also by the NSF-Material Science & Engineering Center (MRSEC) program at the University of Utah (DMR-1121252).

Enhancing Light Emission of ZnO-Nanofilm/Si-Micropillar Heterostructure Arrays by Piezo-Phototronic Effect.

PubMed

Li, Xiaoyi; Chen, Mengxiao; Yu, Ruomeng; Zhang, Taiping; Song, Dongsheng; Liang, Renrong; Zhang, Qinglin; Cheng, Shaobo; Dong, Lin; Pan, Anlian; Wang, Zhong Lin; Zhu, Jing; Pan, Caofeng

2015-06-22

n-ZnO nanofilm/p-Si micropillar heterostructure light-emitting diode (LED) arrays for white light emissions are achieved and the light emission intensity of LED array is enhanced by 120% under -0.05% compressive strains. These results indicate a promising approach to fabricate Si-based light-emitting components with high performances enhanced by piezo-phototronic effect, with potential applications in touchpad technology, personalized signatures, smart skin, and silicon-based photonic integrated circuits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimal temperature control of tissue embedded with gold nanoparticles for enhanced thermal therapy based on two-energy equation model.

PubMed

Wang, Shen-Ling; Qi, Hong; Ren, Ya-Tao; Chen, Qin; Ruan, Li-Ming

2018-05-01

Thermal therapy is a very promising method for cancer treatment, which can be combined with chemotherapy, radiotherapy and other programs for enhanced cancer treatment. In order to get a better effect of thermal therapy in clinical applications, optimal internal temperature distribution of the tissue embedded with gold nanoparticles (GNPs) for enhanced thermal therapy was investigated in present research. The Monte Carlo method was applied to calculate the heat generation of the tissue embedded with GNPs irradiated by continuous laser. To have a better insight into the physical problem of heat transfer in tissues, the two-energy equation was employed to calculate the temperature distribution of the tissue in the process of GNPs enhanced therapy. The Arrhenius equation was applied to evaluate the degree of permanent thermal damage. A parametric study was performed to investigate the influence factors on the tissue internal temperature distribution, such as incident light intensity, the GNPs volume fraction, the periodic heating and cooling time, and the incident light position. It was found that period heating and cooling strategy can effectively avoid overheating of skin surface and heat damage of healthy tissue. Lower GNPs volume fraction will be better for the heat source distribution. Furthermore, the ring heating strategy is superior to the central heating strategy in the treatment effect. All the analysis provides theoretical guidance for optimal temperature control of tissue embedded with GNP for enhanced thermal therapy. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhanced external quantum efficiency in GaN-based vertical-type light-emitting diodes by localized surface plasmons

PubMed Central

Yao, Yung-Chi; Hwang, Jung-Min; Yang, Zu-Po; Haung, Jing-Yu; Lin, Chia-Ching; Shen, Wei-Chen; Chou, Chun-Yang; Wang, Mei-Tan; Huang, Chun-Ying; Chen, Ching-Yu; Tsai, Meng-Tsan; Lin, Tzu-Neng; Shen, Ji-Lin; Lee, Ya-Ju

2016-01-01

Enhancement of the external quantum efficiency of a GaN-based vertical-type light emitting diode (VLED) through the coupling of localized surface plasmon (LSP) resonance with the wave-guided mode light is studied. To achieve this experimentally, Ag nanoparticles (NPs), as the LSP resonant source, are drop-casted on the most top layer of waveguide channel, which is composed of hydrothermally synthesized ZnO nanorods capped on the top of GaN-based VLED. Enhanced light-output power and external quantum efficiency are observed, and the amount of enhancement remains steady with the increase of the injected currents. To understand the observations theoretically, the absorption spectra and the electric field distributions of the VLED with and without Ag NPs decorated on ZnO NRs are determined using the finite-difference time-domain (FDTD) method. The results prove that the observation of enhancement of the external quantum efficiency can be attributed to the creation of an extra escape channel for trapped light due to the coupling of the LSP with wave-guided mode light, by which the energy of wave-guided mode light can be transferred to the efficient light scattering center of the LSP. PMID:26935648

Extrinsic photoresponse enhancement under additional intrinsic photoexcitation in organic semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kounavis, P., E-mail: pkounavis@upatras.gr

2016-06-28

Dual light beam photoresponse experiments are employed to explore the photoresponse under simultaneous extrinsic and intrinsic photoexcitation of organic semiconductors. The photoresponse of a red modulated light extrinsic photoexcitation is found that can be significantly enhanced under an additional blue bias-light intrinsic photoexcitation in two terminal pentacene films on glass substrates. From the frequency resolved photoresponse, it is deduced that the phenomenon of photoresponse enhancement can be attributed to an increase in the extrinsic photogeneration rate of the red modulated light and/or an improvement of the drift velocity of carriers under an additional blue light intrinsic photoexcitation. The possible predominantmore » extrinsic photogeneration mechanism, which can be compatible with the observed dependence of the photoresponse enhancement on the frequency and on the light intensities of the red and blue light excitation, is the singlet exciton dissociation through electron transfer to acceptor-like traps. Moreover, an improvement in the drift velocity of carriers traversing grain boundaries with potential energy barriers, which may be reduced by trapping of minority carriers created from the intrinsic photoexcitation, may partly contribute to the photoresponse enhancement.« less

Phytochrome A Mediates Blue-Light Enhancement of Second-Positive Phototropism in Arabidopsis

PubMed Central

Sullivan, Stuart; Hart, Jaynee E.; Rasch, Patrick; Walker, Catriona H.; Christie, John M.

2016-01-01

Hypocotyl phototropism of etiolated Arabidopsis seedlings is primarily mediated by the blue-light receptor kinase phototropin 1 (phot1). Phot1-mediated curvature to continuous unilateral blue light irradiation (0.5 μmol m−2 s−1) is enhanced by overhead pre-treatment with red light (20 μmol m−2 s−1 for 15 min) through the action of phytochrome (phyA). Here, we show that pre-treatment with blue light is equally as effective in eliciting phototropic enhancement and is dependent on phyA. Although blue light pre-treatment was sufficient to activate early phot1 signaling events, phot1 autophosphorylation in vivo was not found to be saturated, as assessed by subsequently measuring phot1 kinase activity in vitro. However, enhancement effects by red and blue light pre-treatment were not observed at higher intensities of phototropic stimulation (10 μmol m−2 s−1). Phototropic enhancement by red and blue light pre-treatments to 0.5 μmol m−2 s−1 unilateral blue light irradiation was also lacking in transgenic Arabidopsis where PHOT1 expression was restricted to the epidermis. Together, these findings indicate that phyA-mediated effects on phot1 signaling are restricted to low intensities of phototropic stimulation and originate from tissues other than the epidermis. PMID:27014313

Phytochrome A Mediates Blue-Light Enhancement of Second-Positive Phototropism in Arabidopsis.

PubMed

Sullivan, Stuart; Hart, Jaynee E; Rasch, Patrick; Walker, Catriona H; Christie, John M

2016-01-01

Hypocotyl phototropism of etiolated Arabidopsis seedlings is primarily mediated by the blue-light receptor kinase phototropin 1 (phot1). Phot1-mediated curvature to continuous unilateral blue light irradiation (0.5 μmol m(-2) s(-1)) is enhanced by overhead pre-treatment with red light (20 μmol m(-2) s(-1) for 15 min) through the action of phytochrome (phyA). Here, we show that pre-treatment with blue light is equally as effective in eliciting phototropic enhancement and is dependent on phyA. Although blue light pre-treatment was sufficient to activate early phot1 signaling events, phot1 autophosphorylation in vivo was not found to be saturated, as assessed by subsequently measuring phot1 kinase activity in vitro. However, enhancement effects by red and blue light pre-treatment were not observed at higher intensities of phototropic stimulation (10 μmol m(-2) s(-1)). Phototropic enhancement by red and blue light pre-treatments to 0.5 μmol m(-2) s(-1) unilateral blue light irradiation was also lacking in transgenic Arabidopsis where PHOT1 expression was restricted to the epidermis. Together, these findings indicate that phyA-mediated effects on phot1 signaling are restricted to low intensities of phototropic stimulation and originate from tissues other than the epidermis.

High-contrast fluorescence imaging based on the polarization dependence of the fluorescence enhancement using an optical interference mirror slide.

PubMed

Yasuda, Mitsuru; Akimoto, Takuo

2015-01-01

High-contrast fluorescence imaging using an optical interference mirror (OIM) slide that enhances the fluorescence from a fluorophore located on top of the OIM surface is reported. To enhance the fluorescence and reduce the background light of the OIM, transverse-electric-polarized excitation light was used as incident light, and the transverse-magnetic-polarized fluorescence signal was detected. As a result, an approximate 100-fold improvement in the signal-to-noise ratio was achieved through a 13-fold enhancement of the fluorescence signal and an 8-fold reduction of the background light.

Au nanorods-incorporated plasmonic-enhanced inverted organic solar cells

NASA Astrophysics Data System (ADS)

Peng, Ling; Mei, Yang; Chen, Shu-Fen; Zhang, Yu-Pei; Hao, Jing-Yu; Deng, Ling-Ling; Huang, Wei

2015-11-01

The effect of Au nanorods (NRs) on optical-to-electric conversion efficiency is investigated in inverted polymer solar cells, in which Au NRs are sandwiched between two layers of ZnO. Accompanied by the optimization of thickness of ZnO covered on Au NRs, a high-power conversion efficiency of 3.60% and an enhanced short-circuit current density (JSC) of 10.87 mA/cm2 are achieved in the poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC60BM)-based inverted cell and the power conversion efficiency (PCE) is enhanced by 19.6% compared with the control device. The detailed analyses of the light absorption characteristics, the simulated scattering induced by Au NRs, and the electromagnetic field around Au NRs show that the absorption improvement in the photoactive layer due to the light scattering from the longitudinal axis and the near-field increase around Au NRs induced by localized surface plasmon resonance plays a key role in enhancing the performances. Project supported by the Ministry of Science and Technology, China (Grant No. 2012CB933301), the National Natural Science Foundation of China (Grant Nos. 61274065, 51173081, 61136003, BZ2010043, 51372119, and 51172110), and the Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions and Synergetic Innovation Center for Organic Electronics and Information Displays, China.

ZnO-based microrockets with light-enhanced propulsion.

PubMed

Dong, Renfeng; Wang, Chun; Wang, Qinglong; Pei, Allen; She, Xueling; Zhang, Yuxian; Cai, Yuepeng

2017-10-12

Improving the propulsion of artificial micro-nanomotors represents an exciting nanotechnology challenge, especially considering their cargo delivery ability and fuel efficiency. In light of the excellent photocatalytic performance of zinc oxide (ZnO) and chemical catalytic properties of platinum (Pt), ZnO-Pt microrockets with light-enhanced propulsion have been developed by atomic layer deposition (ALD) technology. The velocity of such microrockets is dramatically doubled upon irradiation by 77 mW cm -2 ultraviolet (UV) light in 10% H 2 O 2 and is almost 3 times higher than the classic poly(3,4-ethylenedioxythiophene)-Pt microrockets (PEDOT-Pt microrockets) even in 6% H 2 O 2 under the same UV light. In addition, such micromotors not only retain the standard approach to improve propulsion by varying the fuel concentration, but also demonstrate a simple way to enhance the movement velocity by adjusting the UV light intensity. High reversibility and controllable "weak/strong" propulsion can be easily achieved by switching the UV irradiation on or off. Finally, light-enhanced propulsion has been investigated by electrochemical measurements which further confirm the enhanced photocatalytic properties of ZnO and Pt. The successful demonstration of ZnO-based microrockets with excellent light-enhanced propulsion is significant for developing highly efficient synthetic micro-nanomotors which have strong delivery ability and economic fuel requirements for future practical applications in the micro-nanoscale world.

A visible light-induced photocatalytic silver enhancement reaction for gravimetric biosensors.

PubMed

Ko, Wooree; Yim, Changyong; Jung, Namchul; Joo, Jinmyoung; Jeon, Sangmin; Seo, Hyejung; Lee, Soo Suk; Park, Jae Chan

2011-10-07

We have developed a novel microgravimetric immunosensor using a WO(3) nanoparticle-modified immunoassay and a silver enhancement reaction. When the nanoparticles in silver ion solution (i.e.  AgNO(3)) are exposed to visible light, the silver ions are photocatalytically reduced and form a metallic silver coating on the nanoparticles. This silver coating consequently induces changes in the mass and light absorption spectrum. Although photocatalytic reduction reactions can be achieved using ultraviolet (UV) light and TiO(2) nanoparticles as described in our previous publication (Seo et al 2010 Nanotechnology 21 505502), the use of UV light in biosensing applications has drawbacks in that UV light can damage proteins. In addition, conventional quartz crystal substrates must be passivated to prevent undesirable silver ion reduction on their gold-coated sensing surfaces. We addressed these problems by adopting a visible light-induced photocatalytic silver enhancement method using WO(3) nanoparticles and lateral field excited (LFE) quartz crystals. As a proof-of-concept demonstration of the technique, streptavidin was adsorbed onto an LFE quartz crystal, and its mass was enhanced with biotinylated WO(3) nanoparticles, this being followed by a photocatalytic silver enhancement reaction. The mass change due to the enhancement was found to be > 30 times greater than the mass change obtained with the streptavidin alone.

Correlation of different spectral lights with biomass accumulation and production of antioxidant secondary metabolites in callus cultures of medicinally important Prunella vulgaris L.

PubMed

Fazal, Hina; Abbasi, Bilal Haider; Ahmad, Nisar; Ali, Syed Shujait; Akbar, Fazal; Kanwal, Farina

2016-06-01

Light is one of the key elicitors that directly fluctuates plant developmental processes and biosynthesis of secondary metabolites. In this study, the effects of various spectral lights on biomass accumulation and production of antioxidant secondary metabolites in callus cultures of Prunella vulgaris were investigated. Among different spectral lights, green light induced the maximum callogenic response (95%). Enhanced fresh biomass accumulation was observed in log phases on day-35, when callus cultures were exposed to yellow and violet lights. Yellow light induced maximum biomass accumulation (3.67g/100ml) from leaf explants as compared to control (1.27g/100ml). In contrast, violet lights enhanced biomass accumulation (3.49g/100ml) from petiole explant. Maximum total phenolics content (TPC; 23.9mg/g-DW) and total flavonoids content (TFC; 1.65mg/g-DW) were observed when cultures were grown under blue lights. In contrast, green and yellow lights enhanced total phenolics production (TPP; 112.52g/100ml) and total flavonoids production (TFP; 9.64g/100ml) as compared to control. The calli grown under green, red and blue lights enhanced DPPH-free radical scavenging activity (DFRSA; 91.3%, 93.1% and 93%) than control (56.44%) respectively. The DFRSA was correlated either with TPC and TFC or TPP and TFP. Furthermore, yellow lights enhanced superoxide dismutase (SOD), peroxidase (POD) and protease activities, however, the content of total protein (CTP) was higher in control cultures (186μg BSAE/mg FW) as compared to spectral lights. These results suggest that the exposure of callus cultures to various spectral lights have shown a key role in biomass accumulation and production of antioxidant secondary metabolites. Copyright © 2016 Elsevier B.V. All rights reserved.

Eastern Kodak Company

DOE Office of Scientific and Technical Information (OSTI.GOV)

Y.S. Tyan

2009-06-30

Lighting consumes more than 20% of electricity generated in the United States. Solid state lighting relies upon either inorganic or organic light-emitting diodes (OLEDs). OLED devices because of their thinness, fast response, excellent color, and efficiency could become the technology of choice for future lighting applications, provided progress is made to increase power efficiency and device lifetime and to develop cost-effective manufacturing processes. As a first step in this process, Eastman Kodak Company has demonstrated an OLED device architecture having an efficacy over 50 lm/W that exceeds the specifications of DOE Energy Star Program Requirements for Solid State Lighting. Themore » project included work designed to optimize an OLED device, based on a stacked-OLED structure, with performance parameters of: low voltage; improved light extraction efficiency; improved internal quantum efficiency; and acceptable lifetime. The stated goal for the end of the project was delivery of an OLED device architecture, suitable for development into successful commercial products, having over 50 lum/W power efficiency and 10,000 hours lifetime at 1000 cd/m{sup 2}. During the project, Kodak developed and tested a tandem hybrid IES device made with a fluorescent blue emitter, a phosphorescent yellow emitter, and a phosphorescent red emitter in a stacked structure. The challenge was to find low voltage materials that do not absorb excessive amounts of emitted light when the extraction enhancement structure is applied. Because an extraction enhancement structure forces the emitted light to travel several times through the OLED layers before it is emitted, it exacerbates the absorption loss. A variety of ETL and HTL materials was investigated for application in the low voltage SSL device structure. Several of the materials were found to successfully yield low operating device voltages without incurring excessive absorption loss when the extraction enhancement structure was applied. An internal extraction layer comprises two essential components: a light extraction element (LEE) that does the actual extraction of emitted light and a light coupling layer (LCL) that allows the emitted light to interact with the extraction element. Modeling results show that the optical index of the LCL needs to be high, preferably higher than that of the organic layers with an n value of {approx}1.8. In addition, since the OLED structure needs to be built on top of it the LCL needs to be physically and chemically benign. As the project concluded, our focus was on the tandem hybrid device, which proved to be the more efficient architecture. Cost-efficient device fabrication will provide the next challenges with this device architecture in order to allow this architecture to be commercialized.« less

Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching

PubMed Central

Wientjes, Emilie; Renger, Jan; Curto, Alberto G.; Cogdell, Richard; van Hulst, Niek F.

2014-01-01

The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~\

Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching

NASA Astrophysics Data System (ADS)

Wientjes, Emilie; Renger, Jan; Curto, Alberto G.; Cogdell, Richard; van Hulst, Niek F.

2014-06-01

The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~\

Fish scale terrace GaInN/GaN light-emitting diodes with enhanced light extraction

NASA Astrophysics Data System (ADS)

Stark, Christoph J. M.; Detchprohm, Theeradetch; Zhao, Liang; Paskova, Tanya; Preble, Edward A.; Wetzel, Christian

2012-12-01

Non-planar GaInN/GaN light-emitting diodes were epitaxially grown to exhibit steps for enhanced light emission. By means of a large off-cut of the epitaxial growth plane from the c-plane (0.06° to 2.24°), surface morphologies of steps and inclined terraces that resemble fish scale patterns could controllably be achieved. These patterns penetrate the active region without deteriorating the electrical device performance. We find conditions leading to a large increase in light-output power over the virtually on-axis device and over planar sapphire references. The process is found suitable to enhance light extraction even without post-growth processing.

Photonic crystal light source

DOEpatents

Fleming, James G [Albuquerque, NM; Lin, Shawn-Yu [Albuquerque, NM; Bur, James A [Corrales, NM

2004-07-27

A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

Effect of blue light radiation on curcumin-induced cell death of breast cancer cells

NASA Astrophysics Data System (ADS)

Zeng, X. B.; Leung, A. W. N.; Xia, X. S.; Yu, H. P.; Bai, D. Q.; Xiang, J. Y.; Jiang, Y.; Xu, C. S.

2010-06-01

In the present study, we have successfully set up a novel blue light source with the power density of 9 mW/cm2 and the wavelength of 435.8 nm and then the novel light source was used to investigate the effect of light radiation on curcumin-induced cell death. The cytotoxicity was investigated 24 h after the treatment of curcumin and blue light radiation together using MTT reduction assay. Nuclear chromatin was observed using a fluorescent microscopy with Hoechst33258 staining. The results showed blue light radiation could significantly enhance the cytotoxicity of curcumin on the MCF-7 cells and apoptosis induction. These findings demonstrated that blue light radiation could enhance curcumin-induced cell death of breast cancer cells, suggesting light radiation may be an efficient enhancer of curcumin in the management of breast cancer.

Enhancement of the light output power of InGaN/GaN light-emitting diodes grown on pyramidal patterned sapphire substrates in the micro- and nanoscale

NASA Astrophysics Data System (ADS)

Gao, Haiyong; Yan, Fawang; Zhang, Yang; Li, Jinmin; Zeng, Yiping; Wang, Guohong

2008-01-01

Sapphire substrates were patterned by a chemical wet etching technique in the micro- and nanoscale to enhance the light output power of InGaN/GaN light-emitting diodes (LEDs). InGaN/GaN LEDs on a pyramidal patterned sapphire substrate in the microscale (MPSS) and pyramidal patterned sapphire substrate in the nanoscale (NPSS) were grown by metalorganic chemical vapor deposition. The characteristics of the LEDs fabricated on the MPSS and NPSS prepared by wet etching were studied and the light output powers of the LEDs fabricated on the MPSS and NPSS increased compared with that of the conventional LEDs fabricated on planar sapphire substrates. In comparison with the planar sapphire substrate, an enhancement in output power of about 29% and 48% is achieved with the MPSS and NPSS at an injection current of 20 mA, respectively. This significant enhancement is attributable to the improvement of the epitaxial quality of GaN-based epilayers and the improvement of the light extraction efficiency by patterned sapphire substrates. Additionally, the NPSS is more effective to enhance the light output power than the MPSS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peer, Akshit; Biswas, Rana; Park, Joong -Mok

Here, we demonstrate enhanced absorption in solar cells and enhanced light emission in OLEDs by light interaction with a periodically structured microlens array. We simulate n-i-p perovskite solar cells with a microlens at the air-glass interface, with rigorous scattering matrix simulations. The microlens focuses light in nanoscale regions within the absorber layer enhancing the solar cell. Optimal period of ~700 nm and microlens height of ~800-1000 nm, provides absorption (photocurrent) enhancement of 6% (6.3%). An external polymer microlens array on the air-glass side of the OLED generates experimental and theoretical enhancements >100%, by outcoupling trapped modes in the glass substrate.

Broadband Enhancement of Spontaneous Emission in Two-Dimensional Semiconductors Using Photonic Hypercrystals.

PubMed

Galfsky, Tal; Sun, Zheng; Considine, Christopher R; Chou, Cheng-Tse; Ko, Wei-Chun; Lee, Yi-Hsien; Narimanov, Evgenii E; Menon, Vinod M

2016-08-10

The low quantum yield observed in two-dimensional semiconductors of transition metal dichalcogenides (TMDs) has motivated the quest for approaches that can enhance the light emission from these systems. Here, we demonstrate broadband enhancement of spontaneous emission and increase in Raman signature from archetype two-dimensional semiconductors: molybdenum disulfide (MoS2) and tungsten disulfide (WS2) by placing the monolayers in the near field of a photonic hypercrystal having hyperbolic dispersion. Hypercrystals are characterized by a large broadband photonic density of states due to hyperbolic dispersion while having enhanced light in/out coupling by a subwavelength photonic crystal lattice. This dual advantage is exploited here to enhance the light emission from the 2D TMDs and can be utilized for developing light emitters and solar cells using two-dimensional semiconductors.

Improvement of the extravehicular activity suit for the MIR orbiting station program.

PubMed

Severin, G; Abramov, I; Svertshek, V; Stoklitsky, A

1996-09-01

Since 1977, EVA suits of the semi-rigid type have been used to support sorties from Russian orbiting stations. Currently, within the MIR station program, the Orlan-DMA, the latest modification of the Orlan semi-rigid EVA suit is used by crewmembers. Quite some experience has been gained by Russia in operations of the Orlan type suits. It has proved the advantages of the EVA suit of a semi-rigid configuration, featuring donning/doffing through a hinged backpack door with a built-in life support system. Meanwhile there were some wishes and comments from the crewmembers addressed to the enclosure design and some LSS components. Currently a number of ways and methods are being developed to improve operational characteristics of the suit as well as to enhance its reliability and lifetime. The forthcoming EVAs to be performed by the STS-MIR crewmembers and future EVAs from the common airlock of the International Space Station Alpha make implementation of the planned improvements even more consistent. The paper analyzes the experience gained in the Orlan-DMA operation and discusses planned improvements in light of the forthcoming activities. In particular the Orlan enhancement program is aimed to make the donning/doffing easier, enhance enclosure mobility, improve the condensate removal unit, increase the CCC (Contamination Control Cartridge) operation time and simplify the onboard subsystem design concept.

Light regulation of the growth response in corn root gravitropism

NASA Technical Reports Server (NTRS)

Kelly, M. O.; Leopold, A. C.

1992-01-01

Roots of Merit variety corn (Zea mays L.) require red light for orthogravitropic curvature. Experiments were undertaken to identify the step in the pathway from gravity perception to asymmetric growth on which light may act. Red light was effective in inducing gravitropism whether it was supplied concomitant with or as long as 30 minutes after the gravity stimulus (GS). The presentation time was the same whether the GS was supplied in red light or in darkness. Red light given before the GS slightly enhanced the rate of curvature but had little effect on the lag time or on the final curvature. This enhancement was expanded by a delay between the red light pulse and the GS. These results indicate that gravity perception and at least the initial transduction steps proceed in the dark. Light may regulate the final growth (motor) phase of gravitropism. The time required for full expression of the light enhancement of curvature is consistent with its involvement in some light-stimulated biosynthetic event.

Enhancing performance of LCoS-SLM as adaptive optics by using computer-generated holograms modulation software

NASA Astrophysics Data System (ADS)

Tsai, Chun-Wei; Lyu, Bo-Han; Wang, Chen; Hung, Cheng-Chieh

2017-05-01

We have already developed multi-function and easy-to-use modulation software that was based on LabVIEW system. There are mainly four functions in this modulation software, such as computer generated holograms (CGH) generation, CGH reconstruction, image trimming, and special phase distribution. Based on the above development of CGH modulation software, we could enhance the performance of liquid crystal on silicon - spatial light modulator (LCoSSLM) as similar as the diffractive optical element (DOE) and use it on various adaptive optics (AO) applications. Through the development of special phase distribution, we are going to use the LCoS-SLM with CGH modulation software into AO technology, such as optical microscope system. When the LCOS-SLM panel is integrated in an optical microscope system, it could be placed on the illumination path or on the image forming path. However, LCOS-SLM provides a program-controllable liquid crystal array for optical microscope. It dynamically changes the amplitude or phase of light and gives the obvious advantage, "Flexibility", to the system

Light-Output Enhancement of GaN-Based Light-Emitting Diodes with Three-Dimensional Backside Reflectors Patterned by Microscale Cone Array

PubMed Central

Hu, Jinyong; Wang, Hong

2014-01-01

Three-dimensional (3D) backside reflector, compared with flat reflectors, can improve the probability of finding the escape cone for reflecting lights and thus enhance the light-extraction efficiency (LEE) for GaN-based light-emitting diode (LED) chips. A triangle-lattice of microscale SiO2 cone array followed by a 16-pair Ti3O5/SiO2 distributed Bragg reflector (16-DBR) was proposed to be attached on the backside of sapphire substrate, and the light-output enhancement was demonstrated by numerical simulation and experiments. The LED chips with flat reflectors or 3D reflectors were simulated using Monte Carlo ray tracing method. It is shown that the LEE increases as the reflectivity of backside reflector increases, and the light-output can be significantly improved by 3D reflectors compared to flat counterparts. It can also be observed that the LEE decreases as the refractive index of the cone material increases. The 3D 16-DBR patterned by microscale SiO2 cone array benefits large enhancement of LEE. This microscale pattern was prepared by standard photolithography and wet-etching technique. Measurement results show that the 3D 16-DBR can provide 12.1% enhancement of wall-plug efficiency, which is consistent with the simulated value of 11.73% for the enhancement of LEE. PMID:25133262

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors

PubMed Central

Li, T.; Heuvelink, E.; Dueck, T. A.; Janse, J.; Gort, G.; Marcelis, L. F. M.

2014-01-01

Background and Aims Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Methods Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. Key Results The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less photoinhibition at the top of the canopy when global irradiance was high. Conclusions Diffuse light enhanced crop photosynthesis. A more uniform horizontal PPFD distribution played the most important role in this enhancement, and a more uniform vertical PPFD distribution and higher leaf photosynthetic capacity contributed more to the enhancement of crop photosynthesis than did higher values of LAI. PMID:24782436

High Burnup Effects Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barner, J.O.; Cunningham, M.E.; Freshley, M.D.

1990-04-01

This is the final report of the High Burnup Effects Program (HBEP). It has been prepared to present a summary, with conclusions, of the HBEP. The HBEP was an international, group-sponsored research program managed by Battelle, Pacific Northwest Laboratories (BNW). The principal objective of the HBEP was to obtain well-characterized data related to fission gas release (FGR) for light water reactor (LWR) fuel irradiated to high burnup levels. The HBEP was organized into three tasks as follows: Task 1 -- high burnup effects evaluations; Task 2 -- fission gas sampling; and Task 3 -- parameter effects study. During the coursemore » of the HBEP, a program that extended over 10 years, 82 fuel rods from a variety of sources were characterized, irradiated, and then examined in detail after irradiation. The study of fission gas release at high burnup levels was the principal objective of the program and it may be concluded that no significant enhancement of fission gas release at high burnup levels was observed for the examined rods. The rim effect, an as yet unquantified contributor to athermal fission gas release, was concluded to be the one truly high-burnup effect. Though burnup enhancement of fission gas release was observed to be low, a full understanding of the rim region and rim effect has not yet emerged and this may be a potential area of further research. 25 refs., 23 figs., 4 tabs.« less

Biological optimization systems for enhancing photosynthetic efficiency and methods of use

DOEpatents

Hunt, Ryan W.; Chinnasamy, Senthil; Das, Keshav C.; de Mattos, Erico Rolim

2012-11-06

Biological optimization systems for enhancing photosynthetic efficiency and methods of use. Specifically, methods for enhancing photosynthetic efficiency including applying pulsed light to a photosynthetic organism, using a chlorophyll fluorescence feedback control system to determine one or more photosynthetic efficiency parameters, and adjusting one or more of the photosynthetic efficiency parameters to drive the photosynthesis by the delivery of an amount of light to optimize light absorption of the photosynthetic organism while providing enough dark time between light pulses to prevent oversaturation of the chlorophyll reaction centers are disclosed.

Facile one-pot synthesis of flower-like AgCl microstructures and enhancing of visible light photocatalysis

PubMed Central

2013-01-01

Flower-like AgCl microstructures with enhanced visible light-driven photocatalysis are synthesized by a facile one-pot hydrothermal process for the first time. The evolution process of AgCl from dendritic structures to flower-like octagonal microstructures is investigated quantitatively. Furthermore, the flower-like AgCl microstructures exhibit enhanced ability of visible light-assisted photocatalytic degradation of methyl orange. The enhanced photocatalytic activity of the flower-like AgCl microstructure is attributed to its three-dimensional hierarchical structure exposing with [100] facets. This work provides a fresh view into the insight of electrochemical process and the application area of visible light photocatalysts. PMID:24153176

[Progress of light extraction enhancement in organic light-emitting devices].

PubMed

Liu, Mo; Li, Tong; Wang, Yan; Zhang, Tian-Yu; Xie, Wen-Fa

2011-04-01

Organic light emitting devices (OLEDs) have been used in flat-panel displays and lighting with a near-30-year development. OLEDs possess many advantages, such as full solid device, fast response, flexible display, and so on. As the application of phosphorescence material, the internal quantum efficiency of OLED has almost reached 100%, but its external quantum efficiency is still not very high due to the low light extraction efficiency. In this review the authors summarizes recent advances in light extraction techniques that have been developed to enhance the light extraction efficiency of OLEDs.

Plasmonic Control of Radiation and Absorption Processes in Semiconductor Quantum Dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paiella, Roberto; Moustakas, Theodore D.

This document reviews a research program funded by the DOE Office of Science, which has been focused on the control of radiation and absorption processes in semiconductor photonic materials (including III-nitride quantum wells and quantum dots), through the use of specially designed metallic nanoparticles (NPs). By virtue of their strongly confined plasmonic resonances (i.e., collective oscillations of the electron gas), these nanostructures can concentrate incident radiation into sub-wavelength “hot spots” of highly enhanced field intensity, thereby increasing optical absorption by suitably positioned absorbers. By reciprocity, the same NPs can also dramatically increase the spontaneous emission rate of radiating dipoles locatedmore » within their hot spots. The NPs can therefore be used as optical antennas to enhance the radiation output of the underlying active material and at the same time control the far-field pattern of the emitted light. The key accomplishments of the project include the demonstration of highly enhanced light emission efficiency as well as plasmonic collimation and beaming along geometrically tunable directions, using a variety of plasmonic excitations. Initial results showing the reverse functionality (i.e., plasmonic unidirectional absorption and photodetection) have also been generated with similar systems. Furthermore, a new paradigm for the near-field control of light emission has been introduced through rigorous theoretical studies, based on the use of gradient metasurfaces (i.e., optical nanoantenna arrays with spatially varying shape, size, and/or orientation). These activities have been complemented by materials development efforts aimed at the synthesis of suitable light-emitting samples by molecular beam epitaxy. In the course of these efforts, a novel technique for the growth of III-nitride quantum dots has also been developed (droplet heteroepitaxy), with several potential advantages in terms of compositional and geometrical control. The results of these studies provide fundamental new understanding of optical processes at the nanoscale, including near-field energy transfer between quantum emitters and photonic nanostructures, dissipation phenomena of plasmonic excitations, and radiation from nanoantennas. Furthermore, they may open the way to entirely new device concepts and applications, in a broad range of disciplines including optoelectronics, sensing, spectroscopy, photovoltaics, and quantum information science. A specific application of particularly strong relevance to the DOE mission is the development of energy efficient LED active materials for solid-state lighting, based on plasmonic enhancement effects.« less

Effects of morphology on the radiative properties of internally mixed light absorbing carbon aerosols with different aging status.

PubMed

Cheng, Tianhai; Wu, Yu; Chen, Hao

2014-06-30

Light absorbing carbon aerosols play a substantial role in climate change through radiative forcing, which is the dominant absorber of solar radiation. Radiative properties of light absorbing carbon aerosols are strongly dependent on the morphological factors and the mixing mechanism of black carbon with other aerosol components. This study focuses on the morphological effects on the optical properties of internally mixed light absorbing carbon aerosols using the numerically exact superposition T-matrix method. Three types aerosols with different aging status such as freshly emitted BC particles, thinly coated light absorbing carbon aerosols, heavily coated light absorbing carbon aerosols are studied. Our study showed that morphological factors change with the aging of internally mixed light absorbing carbon aerosols to result in a dramatic change in their optical properties. The absorption properties of light absorbing carbon aerosols can be enhanced approximately a factor of 2 at 0.67 um, and these enhancements depend on the morphological factors. A larger shell/core diameter ratio of volume-equivalent shell-core spheres (S/C), which indicates the degree of coating, leads to stronger absorption. The enhancement of absorption properties accompanies a greater enhancement of scattering properties, which is reflected in an increase in single scattering albedo (SSA). The enhancement of single scattering albedo due to the morphological effects can reach a factor of 3.75 at 0.67 μm. The asymmetry parameter has a similar yet smaller enhancement. Moreover, the corresponding optical properties of shell-and-core model determined by using Lorenz -Mie solutions are presented for comparison. We found that the optical properties of internally mixed light absorbing carbon aerosol can differ fundamentally from those calculated for the Mie theory shell-and-core model, particularly for thinly coated light absorbing carbon aerosols. Our studies indicate that the complex morphology of internally mixed light absorbing carbon aerosols must be explicitly considered in climate radiation balance.

Enhancing light harvesting and charge transport in organic solar cells via integrating lanthanide-doped upconversation materials

NASA Astrophysics Data System (ADS)

Wang, Fei; Yang, Xiao-Yu; Niu, Meng-si; Feng, Lin; Lv, Cheng-kun; Zhang, Kang-ning; Bi, Peng-qing; Yang, Junliang; Hao, Xiao-Tao

2018-07-01

Irradiation of lanthanide-doped upconversion nanoparticles with infrared light can lead to the emission of visible light, which is subsequently absorbed by the organic photoactive layer resulting in the performance enhancement of organic solar cells (OSCs). In this work, OSCs based on poly (3-hexylthiophene) (P3HT) and Phenyl C61 butyric acid methyl ester (PC61BM) blending ytterbium(III), erbium(III) co-doped sodium yttrium fluoride (NaYF4: Yb3+, Er3+) nanoparticles were fabricated with inverted structures. The results indicated that the short current density (J sc) and fill factor were apparently enhanced from 8.60 mA cm‑2 to 9.31 mA cm‑2 and from 57.96% to 64.84%, respectively, leading to an increment of power conversion efficiency (PCE). The photocurrent improvement may have attributed to the additional absorption light generated from upconversion with 980 nm excitation. The active layers with upconversion nanoparticles were investigated to prove enhanced light harvesting, charge transport and energy transfer from upconversion nanoparticles to P3HT. A synergistic effect of broadening light harvesting, efficient energy transfer process, increased carrier mobility and enhanced exciton dissociation in the polymer bulk heterojunction may contribute to the performance enhancement.

Technology options for an enhanced air cargo system

NASA Technical Reports Server (NTRS)

Winston, M. M.

1979-01-01

A view of potential enhancements to the air cargo system through technology application is provided. NASA's role in addressing deficiencies of the current civil and military air cargo systems is outlined. The evolution of conventional airfreighter design is traced and projected through the 1990's. Also, several advanced airfreighter concepts incorporating unconventional design features are described to show their potentials benefits. A number of ongoing NASA technology programs are discussed to indicate the wide range of advanced technologies offering potential benefits to the air cargo system. The promise of advanced airfreighters is then viewed in light of the future air cargo infrastructure predicted by extensive systems studies. The derived outlook concludes that the aircraft technology benefits may be offset somewhat by adverse economic, environmental, and institutional constraints.

Exploration of Mars by Mariner 9 - Television sensors and image processing.

NASA Technical Reports Server (NTRS)

Cutts, J. A.

1973-01-01

Two cameras equipped with selenium sulfur slow scan vidicons were used in the orbital reconnaissance of Mars by the U.S. Spacecraft Mariner 9 and the performance characteristics of these devices are presented. Digital image processing techniques have been widely applied in the analysis of images of Mars and its satellites. Photometric and geometric distortion corrections, image detail enhancement and transformation to standard map projection have been routinely employed. More specializing applications included picture differencing, limb profiling, solar lighting corrections, noise removal, line plots and computer mosaics. Information on enhancements as well as important picture geometric information was stored in a master library. Display of the library data in graphic or numerical form was accomplished by a data management computer program.

Slow-light-enhanced upconversion for photovoltaic applications in one-dimensional photonic crystals.

PubMed

Johnson, Craig M; Reece, Peter J; Conibeer, Gavin J

2011-10-15

We present an approach to realizing enhanced upconversion efficiency in erbium (Er)-doped photonic crystals. Slow-light-mode pumping of the first Er excited state transition can result in enhanced emission from higher-energy levels that may lead to finite subbandgap external quantum efficiency in crystalline silicon solar cells. Using a straightforward electromagnetic model, we calculate potential field enhancements of more than 18× within he slow-light mode of a one-dimensional photonic crystal and discuss design trade-offs and considerations for photovoltaics.

Close correspondence between the action spectra for the blue light responses of the guard cell and coleoptile chloroplasts, and the spectra for blue light-dependent stomatal opening and coleoptile phototropism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quinones, M.A.; Lu, Zhenmin; Zeiger, E.

1996-03-05

Fluorescence spectroscopy was used to characterize blue light responses from chloroplasts of adaxial guard cells from Pima cotton (Gossypium barbadense) and coleoptile tips from corn (Zea mays). The chloroplast response to blue light was quantified by measurements of the blue light-induced enhancement of a red light-stimulated quenching of chlorophyll a fluorescence. In adaxial (upper) guard cells, low fluence rates of blue light applied under saturating fluence rates of red light enhanced the red light-stimulated fluorescence quenching by up to 50%. In contrast, added blue light did not alter the red light-stimulated quenching from abaxial (lower) guard cells. This response patternmore » paralleled the blue light sensitivity of stomatal opening in the two leaf surfaces. An action spectrum for the blue light-induced enhancement of the red light-stimulated quenching showed a major peak at 450 nm and two minor peaks at 420 and 470 nm. This spectrum matched closely an action spectrum for blue light-stimulated stomatal opening. Coleoptile chloroplasts also showed an enhancement by blue light of red light-stimulated quenching. The action spectrum of this response, showing a major peak at 450 nm, a minor peak at 470 nm, and a shoulder at 430 nm, closely matched an action spectrum for blue light-stimulated coleoptile phototropism. Both action spectra match the absorption spectrum of zeaxanthin, a chloroplastic carotenoid recently implicated in blue light photoreception of both guard cells and coleoptiles. The remarkable similarity between the action spectra for the blue light responses of guard cells and coleoptile chloroplasts and the spectra for blue light-stimulated stomatal opening and phototropism, coupled to the recently reported evidence on a role of zeaxanthin in blue light photoreception, indicates that the guard cell and coleoptile chloroplasts specialize in sensory transduction. 28 refs. 4 figs.« less

Enhanced light extraction of GaN-based light-emitting diodes with periodic textured SiO2 on Al-doped ZnO transparent conductive layer

NASA Astrophysics Data System (ADS)

Yu, Zhao; Bingfeng, Fan; Yiting, Chen; Yi, Zhuo; Zhoujun, Pang; Zhen, Liu; Gang, Wang

2016-07-01

We report an effective enhancement in light extraction of GaN-based light-emitting diodes (LEDs) with an Al-doped ZnO (AZO) transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent through-pore anodic aluminum oxide (AAO) membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 mA and 56% at 100 mA compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage. ).

In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop?

PubMed Central

Wangpraseurt, Daniel; Holm, Jacob B.; Larkum, Anthony W. D.; Pernice, Mathieu; Ralph, Peter J.; Suggett, David J.; Kühl, Michael

2017-01-01

Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching. PMID:28174567

In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop?

PubMed

Wangpraseurt, Daniel; Holm, Jacob B; Larkum, Anthony W D; Pernice, Mathieu; Ralph, Peter J; Suggett, David J; Kühl, Michael

2017-01-01

Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O 2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching.

Development and testing of the EVS 2000 enhanced vision system

NASA Astrophysics Data System (ADS)

Way, Scott P.; Kerr, Richard; Imamura, Joe J.; Arnoldy, Dan; Zeylmaker, Richard; Zuro, Greg

2003-09-01

An effective enhanced vision system must operate over a broad spectral range in order to offer a pilot an optimized scene that includes runway background as well as airport lighting and aircraft operations. The large dynamic range of intensities of these images is best handled with separate imaging sensors. The EVS 2000 is a patented dual-band Infrared Enhanced Vision System (EVS) utilizing image fusion concepts to provide a single image from uncooled infrared imagers in both the LWIR and SWIR. The system is designed to provide commercial and corporate airline pilots with improved situational awareness at night and in degraded weather conditions. A prototype of this system was recently fabricated and flown on the Boeing Advanced Technology Demonstrator 737-900 aircraft. This paper will discuss the current EVS 2000 concept, show results taken from the Boeing Advanced Technology Demonstrator program, and discuss future plans for EVS systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, R.; McKinstry, C.; Simmons, C.

Since 1995, the Confederated Tribes of the Colville Reservation (Colville Confederated Tribes) have managed the Chief Joseph Kokanee Enhancement Project as part of the Northwest Power Planning Council (NWPPC) Fish and Wildlife Program. Project objectives have focused on understanding natural production of kokanee (a land-locked sockeye salmon) and other fish stocks in the area above Grand Coulee and Chief Joseph Dams on the Columbia River. A 42-month investigation concluded that entrainment at Grand Coulee Dam ranged from 211,685 to 576,676 fish annually. Further analysis revealed that 85% of the total entrainment occurred at the dam's third powerplant. These numbers representmore » a significant loss to the tribal fisheries upstream of the dam. In response to a suggestion by the NWPPC Independent Scientific Review Panel, the scope of work for the Chief Joseph Kokanee Enhancement Project was expanded to include a multiyear pilot test of a strobe light system to help mitigate fish entrainment. This report details the work conducted during the second year of the study by researchers of the Colville Confederated Tribes in collaboration with the Pacific Northwest National Laboratory. The 2002 study period extended from May 18 through July 30. The objective of the study was to determine the efficacy of a prototype strobe light system to elicit a negative phototactic response in kokanee and rainbow trout. The prototype system consisted of six strobe lights affixed to an aluminum frame suspended vertically underwater from a barge secured in the center of the entrance to the third powerplant forebay. The lights, controlled by a computer, were aimed to illuminate a specific region directly upstream of the barge. Three light level treatments were used: 6 of 6 lights on, 3 of 6 lights on, and all lights off. These three treatment conditions were applied for an entire 24-hr day and were randomly assigned within a 3-day block throughout the study period. A seven-transducer splitbeam hydroacoustic system was used to evaluate the effectiveness of the strobe lights in eliciting a negative phototactic response in fish. The transducers were deployed so they tracked fish entering and within the region illuminated by the strobe lights. Two of the seven transducers were mounted to the frame containing the strobe lights and were oriented horizontally. The remaining five transducers were spaced approximately 4 m apart on individual floating frames upstream of the barge, with the transducers looking vertically downward.« less

Uniform Gold-Nanoparticle-Decorated {001}-Faceted Anatase TiO2 Nanosheets for Enhanced Solar-Light Photocatalytic Reactions.

PubMed

Shi, Huimin; Zhang, Shi; Zhu, Xupeng; Liu, Yu; Wang, Tao; Jiang, Tian; Zhang, Guanhua; Duan, Huigao

2017-10-25

The {001}-faceted anatase TiO 2 micro-/nanocrystals have been widely investigated for enhancing the photocatalysis and photoelectrochemical performance of TiO 2 nanostructures, but their practical applications still require improved energy conversion efficiency under solar-light and enhanced cycling stability. In this work, we demonstrate the controlled growth of ultrathin {001}-faceted anatase TiO 2 nanosheets on flexible carbon cloth for enhancing the cycling stability, and the solar-light photocatalytic performance of the synthesized TiO 2 nanosheets can be significantly improved by decorating with vapor-phase-deposited uniformly distributed plasmonic gold nanoparticles. The fabricated Au-TiO 2 hybrid system shows an 8-fold solar-light photocatalysis enhancement factor in photodegrading Rhodamine B, a high photocurrent density of 300 μA cm -2 under the illumination of AM 1.5G, and 100% recyclability under a consecutive long-term cycling measurement. Combined with electromagnetic simulations and systematic control experiments, it is believed that the tandem-type separation and transition of plasmon-induced hot electrons from Au nanoparticles to the {001} facet of anatase TiO 2 , and then to the neighboring {101} facet, is responsible for the enhanced solar-light photochemical performance of the hybrid system. The Au-TiO 2 nanosheet system addresses well the problems of the limited solar-light response of anatase TiO 2 and fast recombination of photogenerated electron-hole pairs, representing a promising high-performance recyclable solar-light-responding system for practical photocatalytic reactions.

White organic light emitting diodes with enhanced internal and external outcoupling for ultra-efficient light extraction and Lambertian emission.

PubMed

Bocksrocker, Tobias; Preinfalk, Jan Benedikt; Asche-Tauscher, Julian; Pargner, Andreas; Eschenbaum, Carsten; Maier-Flaig, Florian; Lemme, Uli

2012-11-05

White organic light emitting diodes (WOLEDs) suffer from poor outcoupling efficiencies. The use of Bragg-gratings to enhance the outcoupling efficiency is very promising for light extraction in OLEDs, but such periodic structures can lead to angular or spectral dependencies in the devices. Here we present a method which combines highly efficient outcoupling by a TiO(2)-Bragg-grating leading to a 104% efficiency enhancement and an additional high quality microlens diffusor at the substrate/air interface. With the addition of this diffusor, we achieved not only a uniform white emission, but also further increased the already improved device efficiency by another 94% leading to an overall enhancement factor of about 4.

Enhanced photoluminescence of Si nanocrystals-doped cellulose nanofibers by plasmonic light scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugimoto, Hiroshi; Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501; Zhang, Ran

2015-07-27

We report the development of bio-compatible cellulose nanofibers doped with light emitting silicon nanocrystals and Au nanoparticles via facile electrospinning. By performing photoluminescence (PL) spectroscopy as a function of excitation wavelength, we demonstrate plasmon-enhanced PL by a factor of 2.2 with negligible non-radiative quenching due to plasmon-enhanced scattering of excitation light from Au nanoparticles to silicon nanocrystals inside the nanofibers. These findings provide an alternative approach for the development of plasmon-enhanced active systems integrated within the compact nanofiber geometry. Furthermore, bio-compatible light-emitting nanofibers prepared by a cost-effective solution-based processing are very promising platforms for biophotonic applications such as fluorescence sensingmore » and imaging.« less

Nanoimprint-Transfer-Patterned Solids Enhance Light Absorption in Colloidal Quantum Dot Solar Cells.

PubMed

Kim, Younghoon; Bicanic, Kristopher; Tan, Hairen; Ouellette, Olivier; Sutherland, Brandon R; García de Arquer, F Pelayo; Jo, Jea Woong; Liu, Mengxia; Sun, Bin; Liu, Min; Hoogland, Sjoerd; Sargent, Edward H

2017-04-12

Colloidal quantum dot (CQD) materials are of interest in thin-film solar cells due to their size-tunable bandgap and low-cost solution-processing. However, CQD solar cells suffer from inefficient charge extraction over the film thicknesses required for complete absorption of solar light. Here we show a new strategy to enhance light absorption in CQD solar cells by nanostructuring the CQD film itself at the back interface. We use two-dimensional finite-difference time-domain (FDTD) simulations to study quantitatively the light absorption enhancement in nanostructured back interfaces in CQD solar cells. We implement this experimentally by demonstrating a nanoimprint-transfer-patterning (NTP) process for the fabrication of nanostructured CQD solids with highly ordered patterns. We show that this approach enables a boost in the power conversion efficiency in CQD solar cells primarily due to an increase in short-circuit current density as a result of enhanced absorption through light-trapping.

Investigation on dispersion in the active optical waveguide resonator

NASA Astrophysics Data System (ADS)

Qiu, Zihan; Gao, Yining; Xie, Wei

2018-03-01

Introducing active gain in the optical waveguide resonator not only compensates the loss, but also can change the dispersion relationship in the ring resonator. It is demonstrated that the group delay time is negative when the resonator is in the undercoupled condition, which also means the resonator exhibits the fast light effect. Theoretical analysis indicates that fast light effect due to anomalous dispersion, would be manipulated by the gain coefficient controlled by the input pump light power and that fast light would enhance scale factor of the optical resonant gyroscope. Resonance optical gyroscope (ROG)'s scale factor for measuring rotation rate is enhanced by anomalous dispersion with superluminal light propagation. The sensitivity of ROG could be enhanced by anomalous dispersion by coupled resonators even considering the effect of anomalous dispersion and propagation gain on broadened linewidth, and this could result in at least two orders of magnitude enhancement in sensitivity.

Plasmonic nanofocusing of light in an integrated silicon photonics platform.

PubMed

Desiatov, Boris; Goykhman, Ilya; Levy, Uriel

2011-07-04

The capability to focus electromagnetic energy at the nanoscale plays an important role in nanoscinece and nanotechnology. It allows enhancing light matter interactions at the nanoscale with applications related to nonlinear optics, light emission and light detection. It may also be used for enhancing resolution in microscopy, lithography and optical storage systems. Hereby we propose and experimentally demonstrate the nanoscale focusing of surface plasmons by constructing an integrated plasmonic/photonic on chip nanofocusing device in silicon platform. The device was tested directly by measuring the optical intensity along it using a near-field microscope. We found an order of magnitude enhancement of the intensity at the tip's apex. The spot size is estimated to be 50 nm. The demonstrated device may be used as a building block for "lab on a chip" systems and for enhancing light matter interactions at the apex of the tip.

Active Enhancement of Slow Light Based on Plasmon-Induced Transparency with Gain Materials.

PubMed

Zhang, Zhaojian; Yang, Junbo; He, Xin; Han, Yunxin; Zhang, Jingjing; Huang, Jie; Chen, Dingbo; Xu, Siyu

2018-06-03

As a plasmonic analogue of electromagnetically induced transparency (EIT), plasmon-induced transparency (PIT) has drawn more attention due to its potential of realizing on-chip sensing, slow light and nonlinear effect enhancement. However, the performance of a plasmonic system is always limited by the metal ohmic loss. Here, we numerically report a PIT system with gain materials based on plasmonic metal-insulator-metal waveguide. The corresponding phenomenon can be theoretically analyzed by coupled mode theory (CMT). After filling gain material into a disk cavity, the system intrinsic loss can be compensated by external pump beam, and the PIT can be greatly fueled to achieve a dramatic enhancement of slow light performance. Finally, a double-channel enhanced slow light is introduced by adding a second gain disk cavity. This work paves way for a potential new high-performance slow light device, which can have significant applications for high-compact plasmonic circuits and optical communication.

Enhanced light output from the nano-patterned InP semiconductor substrate through the nanoporous alumina mask.

PubMed

Jung, Mi; Kim, Jae Hun; Lee, Seok; Jang, Byung Jin; Lee, Woo Young; Oh, Yoo-Mi; Park, Sun-Woo; Woo, Deokha

2012-07-01

A significant enhancement in the light output from nano-patterned InP substrate covered with a nanoporous alumina mask was observed. A uniform nanohole array on an InP semiconductor substrate was fabricated by inductively coupled plasma reactive ion etching (ICP-RIE), using the nanoporous alumina mask as a shadow mask. The light output property of the semiconductor substrate was investigated via photoluminescence (PL) intensity measurement. The InP substrate with a nanohole array showed a more enhanced PL intensity compared with the raw InP substrate without a nanohole structure. After ICP-RIE etching, the light output from the nanoporous InP substrate covered with a nanoporous alumina mask showed fourfold enhanced PL intensity compared with the raw InP substrate. These results can be used as a prospective method for increasing the light output efficiency of optoelectronic devices.

Electrical and Optical Enhancement in Internally Nanopatterned Organic Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Fina, Michael Dane

Organic light-emitting diodes (OLEDs) have made tremendous technological progress in the past two decades and have emerged as a top competitor for next generation light-emitting displays and lighting. State-of-the-art OLEDs have been reported in literature to approach, and even surpass, white fluorescent tube efficiency. However, despite rapid technological progress, efficiency metrics must be improved to compete with traditional inorganic light-emitting diode (LED) technology. Organic materials possess specialized traits that permit manipulations to the light-emitting cavity. Overall, as demonstrated within, these modifications can be used to improve electrical and optical device efficiencies. This work is focused at analyzing the effects that nanopatterned geometric modifications to the organic active layers play on device efficiency. In general, OLED efficiency is complicated by the complex, coupled processes which contribute to spontaneous dipole emission. A composite of three sub-systems (electrical, exciton and optical) ultimately dictate the OLED device efficiency. OLED electrical operation is believed to take place via a low-mobility-modified Schottky injection process. In the injection-limited regime, geometric effects are expected to modify the local electric field leading to device current enhancement. It is shown that the patterning effect can be used to enhance charge carrier parity, thereby enhancing overall recombination. Current density and luminance characteristics are shown to be improved by OLED nanopatterning from both the model developed within and experimental techniques. Next, the optical enhancement effects produced by the nanopatterned array are considered. Finite-difference time-domain (FDTD) simulations are used to determine positional, spectral optical enhancement for the nanopatterned device. The results show beneficial effects to the device performance. The optical enhancements are related to the reduction in internal radiative quenching (improved internal quantum efficiency) and improvement in light extraction (improved outcoupling efficiency). Furthermore, the electrical model is used to construct a positional radiative efficiency map that when combined with the optical enhancement reveals the overall external quantum efficiency enhancement.

Photodetector with enhanced light absorption

DOEpatents

Kane, James

1985-01-01

A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

Focusing of light energy inside a scattering medium by controlling the time-gated multiple light scattering

NASA Astrophysics Data System (ADS)

Jeong, Seungwon; Lee, Ye-Ryoung; Choi, Wonjun; Kang, Sungsam; Hong, Jin Hee; Park, Jin-Sung; Lim, Yong-Sik; Park, Hong-Gyu; Choi, Wonshik

2018-05-01

The efficient delivery of light energy is a prerequisite for the non-invasive imaging and stimulating of target objects embedded deep within a scattering medium. However, the injected waves experience random diffusion by multiple light scattering, and only a small fraction reaches the target object. Here, we present a method to counteract wave diffusion and to focus multiple-scattered waves at the deeply embedded target. To realize this, we experimentally inject light into the reflection eigenchannels of a specific flight time to preferably enhance the intensity of those multiple-scattered waves that have interacted with the target object. For targets that are too deep to be visible by optical imaging, we demonstrate a more than tenfold enhancement in light energy delivery in comparison with ordinary wave diffusion cases. This work will lay a foundation to enhance the working depth of imaging, sensing and light stimulation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simmons, M.A.; McKinstry, C.A.; Simmons, C.S.

Since 1995, the Colville Confederated Tribes have managed the Chief Joseph Kokanee Enhancement Project as part of the Northwest Power Planning Council's (NWPPC) Fish and Wildlife Program. Project objectives have focused on understanding natural production of kokanee (a land-locked sockeye salmon) and other fish stocks in the area above Grand Coulee and Chief Joseph Dams on the Columbia River. A 42-month investigation concluded that entrainment at Grand Coulee Dam ranged from 211,685 to 576,676 fish annually. Further analysis revealed that 85% of the total entrainment occurred at the dam's third powerplant. These numbers represent a significant loss to the tribalmore » fisheries upstream of the dam. In response to a suggestion by the NWPPC's Independent Scientific Review Panel, the scope of work for the Chief Joseph Kokanee Enhancement Project was expanded to include a multiyear pilot test of a strobe light system to help mitigate fish entrainment. This report details the work conducted during the first year of the study by researchers of the Colville Confederated Tribes in collaboration with the Pacific Northwest National Laboratory (PNNL). The objective of the study was to determine the efficacy of a prototype strobe light system to elicit a negative phototactic response in kokanee and rainbow trout. Analysis of the effect of strobe lights on the distribution (numbers) and behavior of kokanee and rainbow trout was based on 51, 683 fish targets detected during the study period (June 30 through August 1, 2001). Study findings include the following: (1) Analysis of the count data indicated that significantly more fish were present when the lights were on compared to off. This was true for both the 24-hr tests as well as the 1-hr tests. Powerplant discharge, distance from lights, and date were significant factors in the analysis. (2) Behavioral results indicated that fish within 14 m of the lights were trying to avoid the lights by swimming across the lighted region or upstream. Fish were also swimming faster and straighter when the lights were on compared to off. (3) The behavioral results were most pronounced for medium- and large-sized fish at night. Medium-sized fish, based on acoustic target strength, were similar to the size of kokanee and rainbow trout released upstream of Grand Coulee Dam. Based on this study and general review of strobe lights, the researchers recommend several modifications and enhancements to the follow-on study in 2002. The recommendations include: (1) modifying the study design to include only the 24-hr on/off treatments, and controlling the discharge at the third powerplant, so it can be included as a design variable; and (2) providing additional data by beginning the study earlier (mid-May) to better capture the kokanee population, deploying an additional splitbeam transducer to sample the region close to the lights, and increasing the number of lights to provide better definition of the lit and unlit region.« less

Engineering photonic and plasmonic light emission enhancement

NASA Astrophysics Data System (ADS)

Lawrence, Nathaniel

Semiconductor photonic devices are a rapidly maturing technology which currently occupy multi-billion dollar markets in the areas of LED lighting and optical data communication. LEDs currently demonstrate the highest luminous efficiency of any light source for general lighting. Long-haul optical data communication currently forms the backbone of the global communication network. Proper design of light management is required for photonic devices, which can increase the overall efficiency or add new device functionality. In this thesis, novel methods for the control of light propagation and confinement are developed for the use in integrated photonic devices. The first part of this work focuses on the engineering of field confinement within deep subwavelength plasmonic resonators for the enhancement of light-matter interaction. In this section, plasmonic ring nanocavities are shown to form gap plasmon modes confined to the dielectric region between two metal layers. The scattering properties, near-field enhancement and photonic density of states of nanocavity devices are studied using analytic theory and 3D finite difference time domain simulations. Plasmonic ring nanocavities are fabricated and characterized using photoluminescence intensity and decay rate measurements. A 25 times increase in the radiative decay rate of Er:Si02 is demonstrated in nanocavities where light is confined to volumes as small as 0.01( ln )3. The potential to achieve lasing, due to the enhancement of stimulated emission rate in ring nanocavities, is studied as a route to Si-compatible plasmon-enhanced nanolasers. The second part of this work focuses on the manipulation of light generated in planar semiconductor devices using arrays of dielectric nanopillars. In particular, aperiodic arrays of nanopillars are engineered for omnidirectional light extraction enhancement. Arrays of Er:SiNx, nanopillars are fabricated and a ten times increase in light extraction is experimentally demonstrated, while simultaneously controlling far-field radiation patterns in ways not possible with periodic arrays. Additionally, analytical scalar diffraction theory is used to study light propagation from Vogel spiral arrays and demonstrate generation of OAM. Using phase shifting interferometry, the presence of OAM is experimentally verified. The use of Vogel spirals presents a new method for the generation of OAM with applications for secure optical communications.

Characterization of adaptation in phototropism of Arabidopsis thaliana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janoudi, A.K.; Poff, K.L.

1991-02-01

Phototropic curvature has been measured for etiolated Arabidopsis thaliana seedlings with and without a preirradiation. A bilateral preirradiation with 450-nm light at a fluence greater than about 0.1 micromole per square meter causes a rapid densensitization to a subsequent 450-nanometer unilateral irradiation at 0.5 micromole per square meter. Following a refractory period, the capacity to respond phototropically recovers to the predesensitization level, and the response is then enhanced. The length of the refractory period is between 10 and 20 minutes. Both the time needed for recovery and the extent of enhancement increase with increasing fluence of the bilateral preirradiation. Basedmore » on the relative spectral sensitivities of desensitization and enhancement, these responses can be separated. Desensitization is induced by blue light but not by red light. Enhancement, however, is induced by both blue and red light. Thus, enhancement can be induced without desensitization but only vice versa. Both desensitization and enhancement affect only the magnitude of the response and do not affect the fluence threshold.« less

Characterization of adaptation in phototropism of Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Poff, K. L.

1991-01-01

Phototropic curvature has been measured for etiolated Arabidopsis thaliana seedlings with and without a preirradiation. A bilateral preirradiation with 450-nm light at a fluence greater than about 0.1 micromole per square meter causes a rapid desensitization to a subsequent 450-nanometer unilateral irradiation at 0.5 micromole per square meter. Following a refractory period, the capacity to respond phototropically recovers to the predesensitization level, and the response is then enhanced. The length of the refractory period is between 10 and 20 minutes. Both the time needed for recovery and the extent of enhancement increase with increasing fluence of the bilateral preirradiation. Based on the relative spectral sensitivities of desensitization and enhancement, these responses can be separated. Desensitization is induced by blue light but not by red light. Enhancement, however, is induced by both blue and red light. Thus, enhancement can be induced without desensitization but not vice versa. Both desensitization and enhancement affect only the magnitude of the response and do not affect the fluence threshold.

Daylight control system device and method

DOEpatents

Paton, John Douglas

2007-03-13

A system and device for and a method of programming and controlling light fixtures is disclosed. A system in accordance with the present invention includes a stationary controller unit that is electrically coupled to the light fixtures. The stationary controller unit is configured to be remotely programmed with a portable commissioning device to automatically control the lights fixtures. The stationary controller unit and the portable commissioning device include light sensors, micro-computers and transceivers for measuring light levels, running programs, storing data and transmitting data between the stationary controller unit and the portable commissioning device. In operation, target light levels selected with the portable commissioning device and the controller unit is remotely programmed to automatically maintain the target level.

Daylight control system, device and method

DOEpatents

Paton, John Douglas

2012-08-28

A system and device for and a method of programming and controlling light fixtures is disclosed. A system in accordance with the present invention includes a stationary controller unit that is electrically coupled to the light fixtures. The stationary controller unit is configured to be remotely programmed with a portable commissioning device to automatically control the lights fixtures. The stationary controller unit and the portable commissioning device include light sensors, micro-computers and transceivers for measuring light levels, running programs, storing data and transmitting data between the stationary controller unit and the portable commissioning device. In operation, target light levels selected with the portable commissioning device and the controller unit is remotely programmed to automatically maintain the target level.

Daylight control system device and method

DOEpatents

Paton, John Douglas

2009-12-01

A system and device for and a method of programming and controlling light fixtures is disclosed. A system in accordance with the present invention includes a stationary controller unit that is electrically coupled to the light fixtures. The stationary controller unit is configured to be remotely programmed with a portable commissioning device to automatically control the lights fixtures. The stationary controller unit and the portable commissioning device include light sensors, micro-computers and transceivers for measuring light levels, running programs, storing data and transmitting data between the stationary controller unit and the portable commissioning device. In operation, target light levels selected with the portable commissioning device and the controller unit is remotely programmed to automatically maintain the target level.

Light-Regulated Electrochemical Sensor Array for Efficiently Discriminating Hazardous Gases.

PubMed

Liang, Hongqiu; Zhang, Xin; Sun, Huihui; Jin, Han; Zhang, Xiaowei; Jin, Qinghui; Zou, Jie; Haick, Hossam; Jian, Jiawen

2017-10-27

Inadequate detection limit and unsatisfactory discrimination features remain the challenging issues for the widely applied electrochemical gas sensors. Quite recently, we confirmed that light-regulated electrochemical reaction significantly enhanced the electrocatalytic activity, and thereby can potentially extend the detection limit to the parts per billion (ppb) level. Nevertheless, impact of the light-regulated electrochemical reaction on response selectivity has been discussed less. Herein, we systematically report on the effect of illumination on discrimination features via design and fabrication of a light-regulated electrochemical sensor array. Upon illumination (light on), response signal to the examined gases (C 3 H 6 , NO, and CO) is selectively enhanced, resulting in the sensor array demonstrating disparate response patterns when compared with that of the sensor array operated at light off. Through processing all the response patterns derived from both light on and light off with a pattern recognition algorithm, a satisfactory discrimination feature is observed. In contrast, apparent mutual interference between NO and CO is found when the sensor array is solely operated without illumination. The impact mechanism of the illumination is studied and it is deduced that the effect of the illumination on the discriminating features can be mainly attributed to the competition of electrocatalytic activity and gas-phase reactivity. If the enhanced electrocatalytic activity (to specific gas) dominates the whole sensing progress, enhancements in the corresponding response signal would be observed upon illumination. Otherwise, illumination gives a negligible impact. Hence, the response signal to part of the examined gases is selectively enhanced by illumination. Conclusively, light-regulated electrochemical reaction would provide an efficient approach to designing future smart sensing devices.

Enhancing Localized Evaporation through Separated Light Absorbing Centers and Scattering Centers

PubMed Central

Zhao, Dengwu; Duan, Haoze; Yu, Shengtao; Zhang, Yao; He, Jiaqing; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2015-01-01

This report investigates the enhancement of localized evaporation via separated light absorbing particles (plasmonic absorbers) and scattering particles (polystyrene nanoparticles). Evaporation has been considered as one of the most important phase-change processes in modern industries. To improve the efficiency of evaporation, one of the most feasible methods is to localize heat at the top water layer rather than heating the bulk water. In this work, the mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat. Different concentrations of both the light absorbing centers and the light scattering centers were evaluated and the evaporation performance can be largely enhanced with the balance between absorbing centers and scattering centers. The findings in this study not only provide a new way to improve evaporation efficiency in plasmonic particle-based solution, but also shed lights on the design of new solar-driven localized evaporation systems. PMID:26606898

Numerical analysis of light extraction enhancement of GaN-based thin-film flip-chip light-emitting diodes with high-refractive-index buckling nanostructures

NASA Astrophysics Data System (ADS)

Yue, Qing-Yang; Yang, Yang; Cheng, Zhen-Jia; Guo, Cheng-Shan

2018-06-01

In this work, the light extraction efficiency enhancement of GaN-based thin-film flip-chip (TFFC) light-emitting diodes (LEDs) with high-refractive-index (TiO2) buckling nanostructures was studied using the three-dimensional finite difference time domain method. Compared with 2-D photonic crystals, the buckling structures have the advantages of a random directionality and a broad distribution in periodicity, which can effectively extract the guided light propagating in all azimuthal directions over a wide spectrum. Numerical studies revealed that the light extraction efficiency of buckling-structured LEDs reaches 1.1 times that of triangular lattice photonic crystals. The effects of the buckling structure feature sizes and the thickness of the N-GaN layer on the light extraction efficiency for TFFC LEDs were also investigated systematically. With optimized structural parameters, a significant light extraction enhancement of about 2.6 times was achieved for TiO2 buckling-structured TFFC LEDs compared with planar LEDs.

Smart human serum albumin-indocyanine green nanoparticles generated by programmed assembly for dual-modal imaging-guided cancer synergistic phototherapy.

PubMed

Sheng, Zonghai; Hu, Dehong; Zheng, Mingbin; Zhao, Pengfei; Liu, Huilong; Gao, Duyang; Gong, Ping; Gao, Guanhui; Zhang, Pengfei; Ma, Yifan; Cai, Lintao

2014-12-23

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), is a light-activated local treatment modality that is under intensive preclinical and clinical investigations for cancer. To enhance the treatment efficiency of phototherapy and reduce the light-associated side effects, it is highly desirable to improve drug accumulation and precision guided phototherapy for efficient conversion of the absorbed light energy to reactive oxygen species (ROS) and local hyperthermia. In the present study, a programmed assembly strategy was developed for the preparation of human serum albumin (HSA)-indocyanine green (ICG) nanoparticles (HSA-ICG NPs) by intermolecular disulfide conjugations. This study indicated that HSA-ICG NPs had a high accumulation with tumor-to-normal tissue ratio of 36.12±5.12 at 24 h and a long-term retention with more than 7 days in 4T1 tumor-bearing mice, where the tumor and its margin, normal tissue were clearly identified via ICG-based in vivo near-infrared (NIR) fluorescence and photoacoustic dual-modal imaging and spectrum-resolved technology. Meanwhile, HSA-ICG NPs efficiently induced ROS and local hyperthermia simultaneously for synergetic PDT/PTT treatments under a single NIR laser irradiation. After an intravenous injection of HSA-ICG NPs followed by imaging-guided precision phototherapy (808 nm, 0.8 W/cm2 for 5 min), the tumor was completely suppressed, no tumor recurrence and treatments-induced toxicity were observed. The results suggest that HSA-ICG NPs generated by programmed assembly as smart theranostic nanoplatforms are highly potential for imaging-guided cancer phototherapy with PDT/PTT synergistic effects.

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors.

PubMed

Li, T; Heuvelink, E; Dueck, T A; Janse, J; Gort, G; Marcelis, L F M

2014-07-01

Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less photoinhibition at the top of the canopy when global irradiance was high. Diffuse light enhanced crop photosynthesis. A more uniform horizontal PPFD distribution played the most important role in this enhancement, and a more uniform vertical PPFD distribution and higher leaf photosynthetic capacity contributed more to the enhancement of crop photosynthesis than did higher values of LAI. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

High-Energy, High-Pulse-Rate Light Sources for Enhanced Time-Resolved Tomographic PIV of Unsteady and Turbulent Flows

DTIC Science & Technology

2017-07-31

Report: High-Energy, High-Pulse-Rate Light Sources for Enhanced Time -Resolved Tomographic PIV of Unsteady & Turbulent Flows The views, opinions and/or...reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching...High-Energy, High-Pulse-Rate Light Sources for Enhanced Time -Resolved Tomographic PIV of Unsteady & Turbulent Flows Report Term: 0-Other Email

Ultra-high enhancement of light focusing through disordered media controlled by mega-pixel modes (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yu, Hyeonseung; Lee, KyeoReh; Park, YongKeun

2017-02-01

Developing an efficient strategy for light focusing through scattering media is an important topic in the study of multiple light scattering. The enhancement factor of the light focusing, defined as the ratio between the optimized intensity and the background intensity is proportional to the number of controlling modes in a spatial light modulator (SLM). The demonstrated enhancement factors in previous studies are typically less than 1,000 due to several limiting factors, such as the slow refresh rate of a LCoS SLM, long optimization time, and lack of an efficient algorithm for high controlling modes. A digital micro-mirror device is an amplitude modulator, which is recently widely used for fast optimization through dynamic biological tissues. The fast frame rate of the DMD up to 16 kHz can also be exploited for increasing the number of controlling modes. However, the manipulation of large pattern data and efficient calculation of the optimized pattern remained as an issue. In this work, we demonstrate the enhancement factor more than 100,000 in focusing through scattering media by using 1 Mega controlling modes of a DMD. Through careful synchronization between a DMD, a photo-detector and an additional computer for parallel optimization, we achieved the unprecedented enhancement factor with 75 mins of the optimization time. We discuss the design principles of the system and the possible applications of the enhanced light focusing.

Enhanced efficiency of light emitting diodes with a nano-patterned gallium nitride surface realized by soft UV nanoimprint lithography

NASA Astrophysics Data System (ADS)

Zhou, Weimin; Min, Guoquan; Song, Zhitang; Zhang, Jing; Liu, Yanbo; Zhang, Jianping

2010-05-01

This paper reports a significant enhancement in the extraction efficiency of nano-patterned GaN light emitting diodes (LED) realized by soft UV nanoimprint lithography. The 2 inch soft stamp was fabricated using a replication stamp of anodic alumina oxide (AAO) membrane. The light output power was enhanced by 10.9% compared to that of the LED sample without a nano-patterned surface. Up to 41% enhancement in photoluminescence intensity was obtained from the nano-patterned GaN LED sample. The method is simple, cheap and suitable for mass production.

Towards lightweight and flexible high performance nanocrystalline silicon solar cells through light trapping and transport layers

NASA Astrophysics Data System (ADS)

Gray, Zachary R.

This thesis investigates ways to enhance the efficiency of thin film solar cells through the application of both novel nano-element array light trapping architectures and nickel oxide hole transport/electron blocking layers. Experimental results independently demonstrate a 22% enhancement in short circuit current density (JSC) resulting from a nano-element array light trapping architecture and a ˜23% enhancement in fill factor (FF) and ˜16% enhancement in open circuit voltage (VOC) resulting from a nickel oxide transport layer. In each case, the overall efficiency of the device employing the light trapping or transport layer was superior to that of the corresponding control device. Since the efficiency of a solar cell scales with the product of JSC, FF, and VOC, it follows that the results of this thesis suggest high performance thin film solar cells can be realized in the event light trapping architectures and transport layers can be simultaneously optimized. The realizations of these performance enhancements stem from extensive process optimization for numerous light trapping and transport layer fabrication approaches. These approaches were guided by numerical modeling techniques which will also be discussed. Key developments in this thesis include (1) the fabrication of nano-element topographies conducive to light trapping using various fabrication approaches, (2) the deposition of defect free nc-Si:H onto structured topographies by switching from SiH4 to SiF 4 PECVD gas chemistry, and (3) the development of the atomic layer deposition (ALD) growth conditions for NiO. Keywords: light trapping, nano-element array, hole transport layer, electron blocking layer, nickel oxide, nanocrystalline silicon, aluminum doped zinc oxide, atomic layer deposition, plasma enhanced chemical vapor deposition, electron beam lithography, ANSYS HFSS.

Light Water Reactor Sustainability Program: Digital Technology Business Case Methodology Guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, Ken; Lawrie, Sean; Hart, Adam

The Department of Energy’s (DOE’s) Light Water Reactor Sustainability Program aims to develop and deploy technologies that will make the existing U.S. nuclear fleet more efficient and competitive. The program has developed a standard methodology for determining the impact of new technologies in order to assist nuclear power plant (NPP) operators in building sound business cases. The Advanced Instrumentation, Information, and Control (II&C) Systems Technologies Pathway is part of the DOE’s Light Water Reactor Sustainability (LWRS) Program. It conducts targeted research and development (R&D) to address aging and reliability concerns with the legacy instrumentation and control and related information systemsmore » of the U.S. operating light water reactor (LWR) fleet. This work involves two major goals: (1) to ensure that legacy analog II&C systems are not life-limiting issues for the LWR fleet and (2) to implement digital II&C technology in a manner that enables broad innovation and business improvement in the NPP operating model. Resolving long-term operational concerns with the II&C systems contributes to the long-term sustainability of the LWR fleet, which is vital to the nation’s energy and environmental security. The II&C Pathway is conducting a series of pilot projects that enable the development and deployment of new II&C technologies in existing nuclear plants. Through the LWRS program, individual utilities and plants are able to participate in these projects or otherwise leverage the results of projects conducted at demonstration plants. Performance advantages of the new pilot project technologies are widely acknowledged, but it has proven difficult for utilities to derive business cases for justifying investment in these new capabilities. Lack of a business case is often cited by utilities as a barrier to pursuing wide-scale application of digital technologies to nuclear plant work activities. The decision to move forward with funding usually hinges on demonstrating actual cost reductions that can be credited to budgets and thereby truly reduce O&M or capital costs. Technology enhancements, while enhancing work methods and making work more efficient, often fail to eliminate workload such that it changes overall staffing and material cost requirements. It is critical to demonstrate cost reductions or impacts on non-cost performance objectives in order for the business case to justify investment by nuclear operators. The Business Case Methodology (BCM) addresses the “benefit” side of the analysis—as opposed to the cost side—and how the organization evaluates discretionary projects (net present value (NPV), accounting effects of taxes, discount rates, etc.). The cost and analysis side is not particularly difficult for the organization and can usually be determined with a fair amount of precision (not withstanding implementation project cost overruns). It is in determining the "benefits" side of the analysis that utilities have more difficulty in technology projects and that is the focus of this methodology.« less

Method for making a photodetector with enhanced light absorption

DOEpatents

Kane, James

1987-05-05

A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

Optimization of subcutaneous vein contrast enhancement

NASA Astrophysics Data System (ADS)

Zeman, Herbert D.; Lovhoiden, Gunnar; Deshmukh, Harshal

2000-05-01

A technique for enhancing the contrast of subcutaneous veins has been demonstrated. This techniques uses a near IR light source and one or more IR sensitive CCD TV cameras to produce a contrast enhanced image of the subcutaneous veins. This video image of the veins is projected back onto the patient's skin using a n LCD video projector. The use of an IR transmitting filter in front of the video cameras prevents any positive feedback from the visible light from the video projector from causing instabilities in the projected image. The demonstration contrast enhancing illuminator has been tested on adults and children, both Caucasian and African-American, and it enhances veins quite well in all cases. The most difficult cases are those where significant deposits of subcutaneous fat are present which make the veins invisible under normal room illumination. Recent attempts to see through fat using different IR wavelength bands and both linearly and circularly polarized light were unsuccessful. The key to seeing through fat turns out to be a very diffuse source of RI light. Results on adult and pediatric subjects are shown with this new IR light source.

3D-printed external light trap for solar cells.

PubMed

van Dijk, Lourens; Paetzold, Ulrich W; Blab, Gerhard A; Schropp, Ruud E I; di Vece, Marcel

2016-05-01

We present a universally applicable 3D-printed external light trap for enhanced absorption in solar cells. The macroscopic external light trap is placed at the sun-facing surface of the solar cell and retro-reflects the light that would otherwise escape. The light trap consists of a reflective parabolic concentrator placed on top of a reflective cage. Upon placement of the light trap, an improvement of 15% of both the photocurrent and the power conversion efficiency in a thin-film nanocrystalline silicon (nc-Si:H) solar cell is measured. The trapped light traverses the solar cell several times within the reflective cage thereby increasing the total absorption in the cell. Consequently, the trap reduces optical losses and enhances the absorption over the entire spectrum. The components of the light trap are 3D printed and made of smoothened, silver-coated thermoplastic. In contrast to conventional light trapping methods, external light trapping leaves the material quality and the electrical properties of the solar cell unaffected. To explain the theoretical operation of the external light trap, we introduce a model that predicts the absorption enhancement in the solar cell by the external light trap. The corresponding calculated path length enhancement shows good agreement with the empirically derived value from the opto-electrical data of the solar cell. Moreover, we analyze the influence of the angle of incidence on the parasitic absorptance to obtain full understanding of the trap performance. © 2015 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons, Ltd.

Key functional role of the optical properties of coral skeletons in coral ecology and evolution.

PubMed

Enríquez, Susana; Méndez, Eugenio R; Hoegh-Guldberg, Ove; Iglesias-Prieto, Roberto

2017-04-26

Multiple scattering of light on coral skeleton enhances light absorption efficiency of coral symbionts and plays a key role in the regulation of their internal diffuse light field. To understand the dependence of this enhancement on skeleton meso- and macrostructure, we analysed the scattering abilities of naked coral skeletons for 74 Indo-Pacific species. Sensitive morphotypes to thermal and light stress, flat-extraplanate and branching corals, showed the most efficient structures, while massive-robust species were less efficient. The lowest light-enhancing scattering abilities were found for the most primitive colonial growth form: phaceloid. Accordingly, the development of highly efficient light-collecting structures versus the selection of less efficient but more robust holobionts to cope with light stress may constitute a trade-off in the evolution of modern symbiotic scleractinian corals, characterizing two successful adaptive solutions. The coincidence of the most important structural modifications with epitheca decline supports the importance of the enhancement of light transmission across coral skeleton in modern scleractinian diversification, and the central role of these symbioses in the design and optimization of coral skeleton. Furthermore, the same ability that lies at the heart of the success of symbiotic corals as coral-reef-builders can also explain the 'Achilles's heel' of these symbioses in a warming ocean. © 2017 The Author(s).

Limitation of Optical Enhancement in Ultra-thin Solar Cells Imposed by Contact Selectivity.

PubMed

Islam, Raisul; Saraswat, Krishna

2018-06-11

Ultra-thin crystalline silicon (c-Si) solar cell suffers both from poor light absorption and minority carrier recombination at the contacts resulting in low contact selectivity. Yet most of the research focuses on improving the light absorption by introducing novel light trapping technique. Our work shows that for ultra-thin absorber, the benefit of optical enhancement is limited by low contact selectivity. Using simulation we observe that performance enhancement from light trapping starts to saturate as the absorber scales down because of the increase in probability of the photo-generated carriers to recombine at the metal contact. Therefore, improving the carrier selectivity of the contacts, which reduces the recombination at contacts, is important to improve the performance of the solar cell beyond what is possible by enhancing light absorption only. The impact of improving contact selectivity increases as the absorber thickness scales below 20 micrometer (μm). Light trapping provides better light management and improving contact selectivity provides better photo-generated carrier management. When better light management increases the number of photo-generated carriers, better carrier management is a useful optimization knob to achieve the efficiency close to the thermodynamic limit. Our work explores a design trade-off in detail which is often overlooked by the research community.

Strong enhancement of emission efficiency in GaN light-emitting diodes by plasmon-coupled light amplification of graphene

NASA Astrophysics Data System (ADS)

Kim, Jong Min; Kim, Sung; Hwang, Sung Won; Kim, Chang Oh; Shin, Dong Hee; Kim, Ju Hwan; Jang, Chan Wook; Kang, Soo Seok; Hwang, Euyheon; Choi, Suk-Ho; El-Gohary, Sherif H.; Byun, Kyung Min

2018-02-01

Recently, we have demonstrated that excitation of plasmon-polaritons in a mechanically-derived graphene sheet on the top of a ZnO semiconductor considerably enhances its light emission efficiency. If this scheme is also applied to device structures, it is then expected that the energy efficiency of light-emitting diodes (LEDs) increases substantially and the commercial potential will be enormous. Here, we report that the plasmon-induced light coupling amplifies emitted light by ˜1.6 times in doped large-area chemical-vapor-deposition-grown graphene, which is useful for practical applications. This coupling behavior also appears in GaN-based LEDs. With AuCl3-doped graphene on Ga-doped ZnO films that is used as transparent conducting electrodes for the LEDs, the average electroluminescence intensity is 1.2-1.7 times enhanced depending on the injection current. The chemical doping of graphene may produce the inhomogeneity in charge densities (i.e., electron/hole puddles) or roughness, which can play a role as grating couplers, resulting in such strong plasmon-enhanced light amplification. Based on theoretical calculations, the plasmon-coupled behavior is rigorously explained and a method of controlling its resonance condition is proposed.

Relaxation System

NASA Technical Reports Server (NTRS)

1987-01-01

Environ Corporation's relaxation system is built around a body lounge, a kind of super easy chair that incorporates sensory devices. Computer controlled enclosure provides filtered ionized air to create a feeling of invigoration, enhanced by mood changing aromas. Occupant is also surrounded by multidimensional audio and the lighting is programmed to change colors, patterns, and intensity periodically. These and other sensory stimulators are designed to provide an environment in which the learning process is stimulated, because research has proven that while an individual is in a deep state of relaxation, the mind is more receptive to new information.

Light-enhanced acid catalysis over a metal-organic framework.

PubMed

Xu, Caiyun; Sun, Keju; Zhou, Yu-Xiao; Ma, Xiao; Jiang, Hai-Long

2018-03-06

A Brønsted acid-functionalized metal-organic framework (MOF), MIL-101-SO 3 H, was prepared for acid-engaged esterification reactions. Strikingly, for the first time, the MOF exhibits significantly light-enhanced activity and possesses excellent activity and recyclability, with even higher activity than H 2 SO 4 under light irradiation.

Simultaneously Enhancing Light Emission and Suppressing Efficiency Droop in GaN Microwire-Based Ultraviolet Light-Emitting Diode by the Piezo-Phototronic Effect.

PubMed

Wang, Xingfu; Peng, Wenbo; Yu, Ruomeng; Zou, Haiyang; Dai, Yejing; Zi, Yunlong; Wu, Changsheng; Li, Shuti; Wang, Zhong Lin

2017-06-14

Achievement of p-n homojuncted GaN enables the birth of III-nitride light emitters. Owing to the wurtzite-structure of GaN, piezoelectric polarization charges present at the interface can effectively control/tune the optoelectric behaviors of local charge-carriers (i.e., the piezo-phototronic effect). Here, we demonstrate the significantly enhanced light-output efficiency and suppressed efficiency droop in GaN microwire (MW)-based p-n junction ultraviolet light-emitting diode (UV LED) by the piezo-phototronic effect. By applying a -0.12% static compressive strain perpendicular to the p-n junction interface, the relative external quantum efficiency of the LED is enhanced by over 600%. Furthermore, efficiency droop is markedly reduced from 46.6% to 7.5% and corresponding droop onset current density shifts from 10 to 26.7 A cm -2 . Enhanced electrons confinement and improved holes injection efficiency by the piezo-phototronic effect are revealed and theoretically confirmed as the physical mechanisms. This study offers an unconventional path to develop high efficiency, strong brightness and high power III-nitride light sources.

LED Lighting Facts® Program Supports Accuracy in SSL Product Information

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Fact sheet that provides a summary of LED Lighting Facts, a program to assure that LED lighting is accurately represented in the marketplace, illustrated by the LED Lighting Facts label to disclose product performance data.

Enhanced photoresponsivity in graphene-silicon slow-light photonic crystal waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Hao, E-mail: zhoufirst@scu.edu.cn, E-mail: tg2342@columbia.edu, E-mail: cheewei.wong@ucla.edu; Optical Nanostructures Laboratory, Columbia University, New York, New York 10027; Gu, Tingyi, E-mail: zhoufirst@scu.edu.cn, E-mail: tg2342@columbia.edu, E-mail: cheewei.wong@ucla.edu

2016-03-14

We demonstrate the enhanced fast photoresponsivity in graphene hybrid structures by combining the ultrafast dynamics of graphene with improved light-matter interactions in slow-light photonic crystal waveguides. With a 200 μm interaction length, a 0.8 mA/W photoresponsivity is achieved in a graphene-silicon Schottky-like photodetector, with an operating bandwidth in excess of 5 GHz and wavelength range at least from 1480 nm to 1580 nm. Fourfold enhancement of the photocurrent is observed in the slow light region, compared to the wavelength far from the photonic crystal bandedge, for a chip-scale broadband fast photodetector.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodwin, Malik

Reliable public lighting remains a critically important and valuable public service in Detroit, Michigan. The Downtown Detroit Energy Efficiency Lighting Program (the, “Program”) was designed and implemented to bring the latest advancements in lighting technology, energy efficiency, public safety and reliability to Detroit’s Central Business District, and the Program accomplished those goals successfully. Downtown’s nighttime atmosphere has been upgraded as a result of the installation of over 1000 new LED roadway lighting fixtures that were installed as part of the Program. The reliability of the lighting system has also improved.

Effects of red light camera enforcement on fatal crashes in large U.S. cities.

PubMed

Hu, Wen; McCartt, Anne T; Teoh, Eric R

2011-08-01

To estimate the effects of red light camera enforcement on per capita fatal crash rates at intersections with signal lights. From the 99 large U.S. cities with more than 200,000 residents in 2008, 14 cities were identified with red light camera enforcement programs for all of 2004-2008 but not at any time during 1992-1996, and 48 cities were identified without camera programs during either period. Analyses compared the citywide per capita rate of fatal red light running crashes and the citywide per capita rate of all fatal crashes at signalized intersections during the two study periods, and rate changes then were compared for cities with and without cameras programs. Poisson regression was used to model crash rates as a function of red light camera enforcement, land area, and population density. The average annual rate of fatal red light running crashes declined for both study groups, but the decline was larger for cities with red light camera enforcement programs than for cities without camera programs (35% vs. 14%). The average annual rate of all fatal crashes at signalized intersections decreased by 14% for cities with camera programs and increased slightly (2%) for cities without cameras. After controlling for population density and land area, the rate of fatal red light running crashes during 2004-2008 for cities with camera programs was an estimated 24% lower than what would have been expected without cameras. The rate of all fatal crashes at signalized intersections during 2004-2008 for cities with camera programs was an estimated 17% lower than what would have been expected without cameras. Red light camera enforcement programs were associated with a statistically significant reduction in the citywide rate of fatal red light running crashes and a smaller but still significant reduction in the rate of all fatal crashes at signalized intersections. The study adds to the large body of evidence that red light camera enforcement can prevent the most serious crashes. Communities seeking to reduce crashes at intersections should consider this evidence. Copyright © 2011 Elsevier Ltd. All rights reserved.

Saudi Vigilance Program: Challenges and lessons learned.

PubMed

Alharf, Adel; Alqahtani, Nasser; Saeed, Ghazi; Alshahrani, Ali; Alshahrani, Mubarak; Aljasser, Nasser; Alquwaizani, Mohammed; Bawazir, Saleh

2018-03-01

Pharmacovigilance is vital to public health. Adopting a robust spontaneous reporting system for adverse drug events can counteract most hazards that arise from utilizing medicinal products. Prior to the establishment of the Saudi Food and Drug Authority (SFDA), the number of pharmacovigilance-related activities in Saudi Arabia was limited. In 2009, the SFDA established the National Pharmacovigilance and Drug Safety Center (Saudi Vigilance). The pharmacovigilance system has remarkably improved during the past few years. Several initiatives have been taken to improve the program's performance. These initiatives include initiation of pharmacovigilance guidelines, enhancement of communication and reporting tools, training sessions for concerned staff and healthcare providers, and compliance from stakeholders. This review article provides an overview of what the Saudi Vigilance program is, focusing on the scope, mission and vision, hierarchy, operational themes, and overall work processes. Additionally, we will shed light on the challenges we encountered during the early phase and on our future plans.

Use of a Reflective Ultraviolet Imaging System (RUVIS) on Two-Dimensional Dust Impressions Created with Footwear on Multiple Substrates

NASA Astrophysics Data System (ADS)

Engelson, Brian Aaron

Footwear impression evidence in dust is often difficult to locate in ambient light and is a fragile medium that both collection and enhancement techniques can destroy or distort. The collection of footwear impression evidence always begins with non-destructive photographic techniques; however, current methods are limited to oblique lighting of the impression followed by an attempt to photograph in situ. For the vast majority of footwear impressions, an interactive collection method, and thus a potentially destructive procedure, is subsequently carried out to gather the evidence. Therefore, alternative non-destructive means for the preservation and enhancement of footwear impressions in dust merits further attention. Previous research performed with reflected ultraviolet (UV) photography and reflected ultraviolet imaging systems (RUVIS) has shown that there are additional non-destructive methodologies that can be applied to the search for and documentation of footwear impressions in dust. Unfortunately, these prior studies did not include robust comparisons to traditional oblique white light, instead choosing to focus on different UV wavelengths. This study, however, seeks to evaluate the use of a RUVIS device paired with a 254 nanometer (nm) UV light source to locate 2-D footwear impressions in dust on multiple substrates against standard oblique white light techniques and assess the visibility of the impression and amount of background interference present. The optimal angle of incident UV light for each substrate was also investigated. Finally, this study applied an image enhancement technique in order to evaluate its usefulness when looking at the visibility of a footwear impression and the amount of background interference present for enhanced white light and RUVIS pictures of footwear impressions in dust. A collection of eight different substrate types was gathered for investigation, including vinyl composition tile (VCT), ceramic tile, marble tile, magazine paper, steel sheet metal, vinyl flooring, wood flooring, and carpet. Heel impressions were applied to the various substrates utilizing vacuum collected dust and normal walking pressure. Each substrate was then explored and photographed in ambient fluorescent light, oblique white light at 0°, 15°, 30°, and 0° with the light source below the surface plane of the substrate, and 254 nm UV light at 0°, 15°, 30°, 45°, 60°, 75°, 90° and 0° with the light source below the surface plane of the substrate. All pictures were evaluated for clarity and visible detail of the footwear impression and the amount of background interference present, selecting for the best images within a lighting condition group. Additional intra- and intergroup comparisons were carried out to explore differences created by the various lighting conditions. Enhanced images were then created with the best scored pictures and evaluated for additional modifications in impression visibility and background interference. Photographs of footwear impressions in dust illuminated with ambient fluorescent light proved to be the most difficult conditions under which a footwear impression could be visualized. However, both oblique white light and 254 nm UV light lighting conditions showed improvements in either visualization or background dropout, or both, over ambient light conditions. An assessment of the white light and 254 nm UV light RUVIS images also demonstrated that the best angles for the light source for all substrates were oblique 0 and oblique 0° below the surface plane of the substrate lighting. It was found that white light photographs generally provided higher visibility ratings, while RUVIS 254 nm UV light photographs provided better grades for reducing background interference. Enhanced images of white light conditions provided generally poorer quality and quantity of details, while enhanced RUVIS images seemed to improve upon these areas. The use of a RUVIS to capture photographs of footwear impression evidence in dust was found to be a successful secondary non-destructive technique that can be paired with traditional oblique white light procedures. Additionally, the use of below the surface plane of the substrate lighting techniques were found to improve either visibility or background dropout, or both, over standard 0 oblique lighting, depending on the light source, and should be employed, when applicable. Finally, further investigation into digital photo-editing enhancement techniques for footwear impression evidence in dust is needed.

Lighting for Tomorrow: What have we learned and what about the day after tomorrow?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, Kelly L.; Foster, Rebecca; McGowan, Terry

2006-08-22

This paper describes Lighting for Tomorrow, a program sponsored by the US Department of Energy Emerging Technologies Program, the American Lighting Association, and the Consortium for Energy Efficiency. The program has conducted a design competition for residential decorative lighting fixtures using energy-efficient light sources. The paper discusses the reasons for development of the design competition, and the intended outcomes of the effort. The two competitive rounds completed to date are described in terms of their specific messaging and rules, direct results, and lessons learned. Experience to date is synthesized relative to the intended outcomes, including new product introductions, increased awarenessmore » of energy efficiency within the lighting industry, and increased participation by lighting showrooms in marketing and selling energy-efficient light fixtures. The paper also highlights the emergence of Lighting for Tomorrow as a forum for addressing market and technical barriers impeding use of energy-efficient lighting in the residential sector. Finally, it describes how Lighting for Tomorrow's current year (2006) program has been designed to respond to lessons from the previous competitions, feedback from the industry, and changes in lighting technology.« less

Light use efficiency for vegetables production in protected and indoor environments

NASA Astrophysics Data System (ADS)

Cocetta, Giacomo; Casciani, Daria; Bulgari, Roberta; Musante, Fulvio; Kołton, Anna; Rossi, Maurizio; Ferrante, Antonio

2017-01-01

In recent years, there is a growing interest for vegetables production in indoor or disadvantaged climatic zones by using greenhouses. The main problem of crop growing indoor or in environment with limited light availability is the correct choice of light source and the quality of lighting spectrum. In greenhouse and indoor cultivations, plant density is higher than in the open field and plants have to compete for light and nutrients. Nowadays, advanced systems for indoor horticulture use light emitting diodes (LED) for improving crop growth, enhancing the plant productivity and favouring the best nutritional quality formation. In closed environments, as indoor growing modules, the lighting system represents the only source of light and its features are fundamental for obtaining the best lighting performances for plant and the most efficient solution. LED lighting engines are more efficient compared to the lighting sources used traditionally in horticulture and allow light spectrum and intensity modulations to enhance the light use efficiency for plants. The lighting distribution and the digital controls are fundamental for tailoring the spectral distribution on each plant in specific moments of its growth and play an important role for optimizing growth and produce high-quality vegetables. LED lights can increase plant growth and yield, but also nutraceutical quality, since some light intensities increase pigments biosynthesis and enhance the antioxidants content of leaves or fruits: in this regards the selection of LED primary light sources in relation to the peaks of the absorbance curve of the plants is important.

Light Water Breeder Reactor fuel rod design and performance characteristics (LWBR Development Program)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, W.R.; Giovengo, J.F.

1987-10-01

Light Water Breeder Reactor (LWBR) fuel rods were designed to provide a reliable fuel system utilizing thorium/uranium-233 mixed-oxide fuel while simultaneously minimizing structural material to enhance fuel breeding. The fuel system was designed to be capable of operating successfully under both load follow and base load conditions. The breeding objective required thin-walled, low hafnium content Zircaloy cladding, tightly spaced fuel rods with a minimum number of support grid levels, and movable fuel rod bundles to supplant control rods. Specific fuel rod design considerations and their effects on performance capability are described. Successful completion of power operations to over 160 percentmore » of design lifetime including over 200 daily load follow cycles has proven the performance capability of the fuel system. 68 refs., 19 figs., 44 tabs.« less

Engine throat/nozzle optics for plume spectroscopy

NASA Technical Reports Server (NTRS)

Bickford, R. L.; Duncan, D. B.

1991-01-01

The Task 2.0 Engine Throat/Nozzle Optics for Plume Spectroscopy, effort was performed under the NASA LeRC Development of Life Prediction Capabilities for Liquid Propellant Rocket Engines program. This Task produced the engineering design of an optical probe to enable spectroscopic measurements within the SSME main chamber. The probe mounts on the SSME nozzle aft manifold and collects light emitted from the throat plane and chamber. Light collected by the probe is transferred to a spectrometer through a fiber optic cable. The design analyses indicate that the probe will function throughout the engine operating cycle and is suitable for both test stand and flight operations. By detecting metallic emissions that are indicative of component degradation or incipient failure, engine shutdown can be initiated before catastrophic failure. This capability will protect valuable test stand hardware and provide enhanced mission safety.

Broadband enhancement of dielectric light trapping nanostructure used in ultra-thin solar cells

NASA Astrophysics Data System (ADS)

Yang, Dong; Xu, Zhaopeng; Bian, Fei; Wang, Haiyan; Wang, Jiazhuang; Sun, Lu

2018-03-01

A dielectric fishnet nanostructure is designed to increase the light trapping capability of ultra-thin solar cells. The complex performance of ultra-thin cells such as the optical response and electrical response are fully quantified in simulation through a complete optoelectronic investigation. The results show that the optimized light trapping nanostructure can enhances the electromagnetic resonance in active layer then lead to extraordinary enhancement of both absorption and light-conversion capabilities in the solar cell. The short-circuit current density increases by 49.46% from 9.40 mA/cm2 to 14.05 mA/cm2 and light-conversion efficiency increases by 51.84% from 9.51% to 14.44% compared to the benchmark, a solar cell with an ITO-GaAs-Ag structure.

Anomalous light trapping enhancement in a two-dimensional gold nanobowl array with an amorphous silicon coating.

PubMed

Yang, Liu; Kou, Pengfei; He, Nan; Dai, Hao; He, Sailing

2017-06-26

A facile polymethyl methacrylate-assisted turnover-transfer approach is developed to fabricate uniform hexagonal gold nanobowl arrays. The bare array shows inferior light trapping ability compared to its inverted counterpart (a gold nanospherical shell array). Surprisingly, after being coated with a 60-nm thick amorphous silicon film, an anomalous light trapping enhancement is observed with a significantly enhanced average absorption (82%), while for the inverted nanostructure, the light trapping becomes greatly weakened with an average absorption of only 66%. Systematic experimental and theoretical results show that the main reason for the opposite light trapping behaviors lies in the top amorphous silicon coating, which plays an important role in mediating the excitation of surface plasmon polaritons and the electric field distributions in both nanostructures.

Enhanced light trapping by focused ion beam (FIB) induced self-organized nanoripples on germanium (100) surface

NASA Astrophysics Data System (ADS)

Kamaliya, Bhaveshkumar; Mote, Rakesh G.; Aslam, Mohammed; Fu, Jing

2018-03-01

In this paper, we demonstrate enhanced light trapping by self-organized nanoripples on the germanium surface. The enhanced light trapping leading to high absorption of light is confirmed by the experimental studies as well as the numerical simulations using the finite-difference time-domain method. We used gallium ion (Ga+) focused ion beam to enable the formation of the self-organized nanoripples on the germanium (100) surface. During the fabrication, the overlap of the scanning beam is varied from zero to negative value and found to influence the orientation of the nanoripples. Evolution of nanostructures with the variation of beam overlap is investigated. Parallel, perpendicular, and randomly aligned nanoripples with respect to the scanning direction are obtained via manipulation of the scanning beam overlap. 95% broadband absorptance is measured in the visible electromagnetic region for the nanorippled germanium surface. The reported light absorption enhancement can significantly improve the efficiency of germanium-silicon based photovoltaic systems.

Multifunctional graphene optoelectronic devices capable of detecting and storing photonic signals.

PubMed

Jang, Sukjae; Hwang, Euyheon; Lee, Youngbin; Lee, Seungwoo; Cho, Jeong Ho

2015-04-08

The advantages of graphene photodetectors were utilized to design a new multifunctional graphene optoelectronic device. Organic semiconductors, gold nanoparticles (AuNPs), and graphene were combined to fabricate a photodetecting device with a nonvolatile memory function for storing photonic signals. A pentacene organic semiconductor acted as a light absorption layer in the device and provided a high hole photocurrent to the graphene channel. The AuNPs, positioned between the tunneling and blocking dielectric layers, acted as both a charge trap layer and a plasmonic light scatterer, which enable storing of the information about the incident light. The proposed pentacene-graphene-AuNP hybrid photodetector not only performed well as a photodetector in the visible light range, it also was able to store the photonic signal in the form of persistent current. The good photodetection performance resulted from the plasmonics-enabled enhancement of the optical absorption and from the photogating mechanisms in the pentacene. The device provided a photoresponse that depended on the wavelength of incident light; therefore, the signal information (both the wavelength and intensity) of the incident light was effectively committed to memory. The simple process of applying a negative pulse gate voltage could then erase the programmed information. The proposed photodetector with the capacity to store a photonic signal in memory represents a significant step toward the use of graphene in optoelectronic devices.

Generating structured light with phase helix and intensity helix using reflection-enhanced plasmonic metasurface at 2 μm

NASA Astrophysics Data System (ADS)

Zhao, Yifan; Du, Jing; Zhang, Jinrun; Shen, Li; Wang, Jian

2018-04-01

Mid-infrared (2-20 μm) light has been attracting great attention in many areas of science and technology. Beyond the extended wavelength range from visible and near-infrared to mid-infrared, shaping spatial structures may add opportunities to grooming applications of mid-infrared photonics. Here, we design and fabricate a reflection-enhanced plasmonic metasurface and demonstrate efficient generation of structured light with the phase helix and intensity helix at 2 μm. This work includes two distinct aspects. First, structured light (phase helix, intensity helix) generation at 2 μm, which is far beyond the ability of conventional spatial light modulators, is enabled by the metasurface with sub-wavelength engineered structures. Second, the self-referenced intensity helix against environmental noise is generated without using a spatially separated light. The demonstrations may open up advanced perspectives to structured light applications at 2 μm, such as phase helix for communications and non-communications (imaging, sensing) and intensity helix for enhanced microscopy and advanced metrology.

Enhancing Three-dimensional Movement Control System for Assemblies of Machine-Building Facilities

NASA Astrophysics Data System (ADS)

Kuzyakov, O. N.; Andreeva, M. A.

2018-01-01

Aspects of enhancing three-dimensional movement control system are given in the paper. Such system is to be used while controlling assemblies of machine-building facilities, which is a relevant issue. The base of the system known is three-dimensional movement control device with optical principle of action. The device consists of multi point light emitter and light receiver matrix. The processing of signals is enhanced to increase accuracy of measurements by switching from discrete to analog signals. Light receiver matrix is divided into four areas, and the output value of each light emitter in each matrix area is proportional to its luminance level. Thus, determing output electric signal value of each light emitter in corresponding area leads to determing position of multipoint light emitter and position of object tracked. This is done by using Case-based reasoning method, the precedent in which is described as integral signal value of each matrix area, coordinates of light receivers, which luminance level is high, and decision to be made in this situation.

Improved defect analysis of Gallium Arsenide solar cells using image enhancement

NASA Technical Reports Server (NTRS)

Kilmer, Louis C.; Honsberg, Christiana; Barnett, Allen M.; Phillips, James E.

1989-01-01

A new technique has been developed to capture, digitize, and enhance the image of light emission from a forward biased direct bandgap solar cell. Since the forward biased light emission from a direct bandgap solar cell has been shown to display both qualitative and quantitative information about the solar cell's performance and its defects, signal processing techniques can be applied to the light emission images to identify and analyze shunt diodes. Shunt diodes are of particular importance because they have been found to be the type of defect which is likely to cause failure in a GaAs solar cell. The presence of a shunt diode can be detected from the light emission by using a photodetector to measure the quantity of light emitted at various current densities. However, to analyze how the shunt diodes affect the quality of the solar cell the pattern of the light emission must be studied. With the use of image enhancement routines, the light emission can be studied at low light emission levels where shunt diode effects are dominant.

Enhanced light extraction from a GaN-based green light-emitting diode with hemicylindrical linear grating structure.

PubMed

Jin, Yuanhao; Yang, Fenglei; Li, Qunqing; Zhu, Zhendong; Zhu, Jun; Fan, Shoushan

2012-07-02

Significant enhancement in the light output from GaN-based green light-emitting diodes (LEDs) was achieved with a hemicylindrical grating structure on the top layer of the diodes. The grating structure was first optimized by the finite-difference time-domain (FDTD) method, which showed that the profile of the grating structure was critical for light extraction efficiency. It was found that the transmission efficiency of the 530 nm light emitted from the inside of the GaN LED increased for incidence angles between 23.58° and 60°. Such a structure was fabricated by electron-beam lithography and an etching method. The light output power from the LED was increased approximately 4.7 times compared with that from a conventional LED. The structure optimization is the key to the great increase in transmission efficiency. Furthermore, the light emitted from the edge of the LED units could be collected and extracted by the grating structures in adjacent LED units, thus enhancing the performance of the whole LED chip.

Interdisciplinary Approach to Fall Prevention in a High-Risk Inpatient Pediatric Population: Quality Improvement Project.

PubMed

Stubbs, Kendra E; Sikes, Lindsay

2017-01-01

Within a tertiary care pediatric medical center, the largest number of inpatient falls (8.84 falls per 1,000 patient days) occurred within a 14-bed rehabilitation/transitional care unit between February and September 2009. An interdisciplinary fall prevention program, called "Red Light, Green Light," was developed to better educate all staff and family members to ensure safety of transfers and ambulation of children with neurological impairments. The purpose of this study was to develop and implement an interdisciplinary pediatric fall prevention program to reduce total falls and falls with family members present in this population. Preintervention 2009 data and longitudinal data from 2010-2014 were obtained from retrospective review of event/incident reports. This quality improvement project was based on inpatient pediatric admissions to a rehabilitation care unit accommodating children with neurological impairments. Data extraction included: total falls, falls with caregiver (alone versus staff versus family), type of falls, and falls by diagnosis. Descriptive statistics were obtained on outcome measures; chi-square statistics were calculated on preintervention and postintervention comparisons. Total falls decreased steadily from 8.84 falls per 1,000 patient days in 2009 to 1.79 falls per 1,000 patient days in 2014 (χ12=3.901, P=.048). Falls with family members present decreased 50% postintervention. (χ12=6.26, P=.012). Limitations included unit size nearly doubled postintervention, event reporting changed to both uncontrolled and controlled therapy falls (safely lowering patient to bed, chair, or floor), and enhanced reporting increased numbers of postintervention falls. The Red Light, Green Light program has resulted in reductions in overall fall rates, falls with family members present, increased staff collaboration, heightened staff and family safety awareness, and a safer environment for patients at high risk for neurological or musculoskeletal impairments. © 2017 American Physical Therapy Association

Soft lithography microlens fabrication and array for enhanced light extraction from organic light emitting diodes (OLEDs)

DOEpatents

Leung, Wai Y.; Park, Joong-Mok; Gan, Zhengqing; Constant, Kristen P.; Shinar, Joseph; Shinar, Ruth; ho, Kai-Ming

2014-06-03

Provided are microlens arrays for use on the substrate of OLEDs to extract more light that is trapped in waveguided modes inside the devices and methods of manufacturing same. Light extraction with microlens arrays is not limited to the light emitting area, but is also efficient in extracting light from the whole microlens patterned area where waveguiding occurs. Large microlens array, compared to the size of the light emitting area, extract more light and result in over 100% enhancement. Such a microlens array is not limited to (O)LEDs of specific emission, configuration, pixel size, or pixel shape. It is suitable for all colors, including white, for microcavity OLEDs, and OLEDs fabricated directly on the (modified) microlens array.

Optical analysis of nanoparticles via enhanced backscattering facilitated by 3-D photonic nanojets

NASA Astrophysics Data System (ADS)

Li, Xu; Chen, Zhigang; Taflove, Allen; Backman, Vadim

2005-01-01

We report the phenomenon of ultra-enhanced backscattering of visible light by nanoparticles facilitated by the 3-D photonic nanojet a sub-diffraction light beam appearing at the shadow side of a plane-waveilluminated dielectric microsphere. Our rigorous numerical simulations show that backscattering intensity of nanoparticles can be enhanced up to eight orders of magnitude when locating in the nanojet. As a result, the enhanced backscattering from a nanoparticle with diameter on the order of 10 nm is well above the background signal generated by the dielectric microsphere itself. We also report that nanojet-enhanced backscattering is extremely sensitive to the size of the nanoparticle, permitting in principle resolving sub-nanometer size differences using visible light. Finally, we show how the position of a nanoparticle could be determined with subdiffractional accuracy by recording the angular distribution of the backscattered light. These properties of photonic nanojets promise to make this phenomenon a useful tool for optically detecting, differentiating, and sorting nanoparticles.

Color image enhancement based on particle swarm optimization with Gaussian mixture

NASA Astrophysics Data System (ADS)

Kattakkalil Subhashdas, Shibudas; Choi, Bong-Seok; Yoo, Ji-Hoon; Ha, Yeong-Ho

2015-01-01

This paper proposes a Gaussian mixture based image enhancement method which uses particle swarm optimization (PSO) to have an edge over other contemporary methods. The proposed method uses the guassian mixture model to model the lightness histogram of the input image in CIEL*a*b* space. The intersection points of the guassian components in the model are used to partition the lightness histogram. . The enhanced lightness image is generated by transforming the lightness value in each interval to appropriate output interval according to the transformation function that depends on PSO optimized parameters, weight and standard deviation of Gaussian component and cumulative distribution of the input histogram interval. In addition, chroma compensation is applied to the resulting image to reduce washout appearance. Experimental results show that the proposed method produces a better enhanced image compared to the traditional methods. Moreover, the enhanced image is free from several side effects such as washout appearance, information loss and gradation artifacts.

Enhancement of electroluminescence from embedded Si quantum dots/SiO2multilayers film by localized-surface-plasmon and surface roughening.

PubMed

Li, Wei; Wang, Shaolei; Hu, Mingyue; He, Sufeng; Ge, Pengpeng; Wang, Jing; Guo, Yan Yan; Zhaowei, Liu

2015-07-03

In this paper, we prepared a novel structure to enhance the electroluminescence intensity from Si quantum dots/SiO2multilayers. An amorphous Si/SiO2 multilayer film was fabricated by plasma-enhanced chemical vapor deposition on a Pt nanoparticle (NP)-coated Si nanopillar array substrate. By thermal annealing, an embedded Si quantum dot (QDs)/SiO2 multilayer film was obtained. The result shows that electroluminescence intensity was significantly enhanced. And, the turn-on voltage of the luminescent device was reduced to 3 V. The enhancement of the light emission is due to the resonance coupling between the localized-surface-plasmon (LSP) of Pt NPs and the band-gap emission of Si QDs/SiO2 multilayers. The other factors were the improved absorption of excitation light and the increase of light extraction ratio by surface roughening structures. These excellent characteristics are promising for silicon-based light-emitting applications.

Enhancement of electroluminescence from embedded Si quantum dots/SiO2multilayers film by localized-surface-plasmon and surface roughening

PubMed Central

Li, Wei; Wang, Shaolei; Hu, Mingyue; He, Sufeng; Ge, Pengpeng; Wang, Jing; Guo, Yan Yan; Zhaowei, Liu

2015-01-01

In this paper, we prepared a novel structure to enhance the electroluminescence intensity from Si quantum dots/SiO2multilayers. An amorphous Si/SiO2 multilayer film was fabricated by plasma-enhanced chemical vapor deposition on a Pt nanoparticle (NP)-coated Si nanopillar array substrate. By thermal annealing, an embedded Si quantum dot (QDs)/SiO2 multilayer film was obtained. The result shows that electroluminescence intensity was significantly enhanced. And, the turn-on voltage of the luminescent device was reduced to 3 V. The enhancement of the light emission is due to the resonance coupling between the localized-surface-plasmon (LSP) of Pt NPs and the band-gap emission of Si QDs/SiO2 multilayers. The other factors were the improved absorption of excitation light and the increase of light extraction ratio by surface roughening structures. These excellent characteristics are promising for silicon-based light-emitting applications. PMID:26138830

Aluminum-nanodisc-induced collective lattice resonances: Controlling the light extraction in organic light emitting diodes

NASA Astrophysics Data System (ADS)

Auer-Berger, Manuel; Tretnak, Veronika; Wenzl, Franz-Peter; Krenn, Joachim R.; List-Kratochvil, Emil J. W.

2017-10-01

We examine aluminum-nanodisc-induced collective lattice resonances as a means to enhance the efficiency of organic light emitting diodes. Thus, nanodisc arrays were embedded in the hole transporting layer of a solution-processed phosphorescent organic blue-light emitting diode. Through extinction spectroscopy, we confirm the emergence of array-induced collective lattice resonances within the organic light emitting diode. Through finite-difference time domain simulations, we show that the collective lattice resonances yield an enhancement of the electric field intensity within the emissive layer. The effectiveness for improving the light generation and light outcoupling is demonstrated by electro-optical characterization, realizing a gain in a current efficiency of 35%.

Using high haze (> 90%) light-trapping film to enhance the efficiency of a-Si:H solar cells

NASA Astrophysics Data System (ADS)

Chu, Wei-Ping; Lin, Jian-Shian; Lin, Tien-Chai; Tsai, Yu-Sheng; Kuo, Chen-Wei; Chung, Ming-Hua; Hsieh, Tsung-Eong; Liu, Lung-Chang; Juang, Fuh-Shyang; Chen, Nien-Po

2012-07-01

The high haze light-trapping (LT) film offers enhanced scattering of light and is applied to a-Si:H solar cells. UV glue was spin coated on glass, and then the LT pattern was imprinted. Finally, a UV lamp was used to cure the UV glue on the glass. The LT film effectively increased the Haze ratio of glass and decreased the reflectance of a-Si:H solar cells. Therefore, the photon path length was increased to obtain maximum absorption by the absorber layer. High Haze LT film is able to enhance short circuit current density and efficiency of the device, as partial composite film generates broader scattering light, thereby causing shorter wave length light to be absorbed by the P layer so that the short circuit current density decreases. In case of lab-made a-Si:H thin film solar cells with v-shaped LT films, superior optoelectronic performances have been found (Voc = 0.74 V, Jsc = 15.62 mA/cm2, F.F. = 70%, and η = 8.09%). We observed ~ 35% enhancement of the short-circuit current density and ~ 31% enhancement of the conversion efficiency.

Enhancing extracellular electron transfer between Pseudomonas aeruginosa PAO1 and light driven semiconducting birnessite.

PubMed

Ren, Guiping; Sun, Yuan; Ding, Yang; Lu, Anhuai; Li, Yan; Wang, Changqiu; Ding, Hongrui

2018-06-02

In recent years, considerable research effort has explored the interaction between semiconducting minerals and microorganisms, such relationship is a promising way to increase the efficiency of bioelectrochemical systems. Herein, the enhancement of electron transfer between birnessite photoanodes and Pseudomonas aeruginosa PAO1 under visible light was investigated. Under light illumination and positive bias, the light-birnessite-PAO1 electrochemical system generated a photocurrent of 279.57 μA/cm 2 , which is 322% and 170% higher than those in the abiotic control and dead culture, suggesting photoenhanced electrochemical interaction between birnessite and Pseudomonas. The I-t curves presented repeatable responses to light on/off cycles, and multi-conditions analyses indicated that the enhanced photocurrent was attributed to the additional redox species associated with P. aeruginosa PAO1 and with the biofilm on birnessite. Electroconductibility analysis was conducted on the biofilm cellularly by conductive atomic force microscope. Pyocyanin was isolated as the biosynthesized extracellular shuttle and characterized by cyclic voltammetry and surface-enhanced Raman spectroscopy. Rapid bioelectron transfer driven by light was observed. The results suggest new opportunities for designing photo-bioelectronic devices and expanding our understanding of extracellular electron transfer with semiconducting minerals under light in nature environments. Copyright © 2018. Published by Elsevier B.V.

Laser-induced periodic structures for light extraction efficiency enhancement of GaN-based light emitting diodes.

PubMed

Chen, Jiun-Ting; Lai, Wei-Chih; Kao, Yu-Jui; Yang, Ya-Yu; Sheu, Jinn-Kong

2012-02-27

The laser-induced periodic surface structure technique was used to form simultaneously dual-scale rough structures (DSRS) with spiral-shaped nanoscale structure inside semi-spherical microscale holes on p-GaN surface to improve the light-extraction efficiency of light-emitting diodes (LEDs). The light output power of DSRS-LEDs was 30% higher than that of conventional LEDs at an injection current of 20 mA. The enhancement in the light output power could be attributed to the increase in the probability of photons to escape from the increased surface area of textured p-GaN surface.

Polarization and Color Filtering Applied to Enhance Photogrammetric Measurements of Reflective Surfaces

NASA Technical Reports Server (NTRS)

Wells, Jeffrey M.; Jones, Thomas W.; Danehy, Paul M.

2005-01-01

Techniques for enhancing photogrammetric measurement of reflective surfaces by reducing noise were developed utilizing principles of light polarization. Signal selectivity with polarized light was also compared to signal selectivity using chromatic filters. Combining principles of linear cross polarization and color selectivity enhanced signal-to-noise ratios by as much as 800 fold. More typical improvements with combining polarization and color selectivity were about 100 fold. We review polarization-based techniques and present experimental results comparing the performance of traditional retroreflective targeting materials, cornercube targets returning depolarized light, and color selectivity.

FY2016 Propulsion Materials Annual Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines and Fuels) teams to develop strategies thatmore » overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.« less

LOX/Hydrocarbon Combustion Instability Investigation

NASA Technical Reports Server (NTRS)

Jensen, R. J.; Dodson, H. C.; Claflin, S. E.

1989-01-01

The LOX/Hydrocarbon Combustion Instability Investigation Program was structured to determine if the use of light hydrocarbon combustion fuels with liquid oxygen (LOX) produces combustion performance and stability behavior similar to the LOX/hydrogen propellant combination. In particular methane was investigated to determine if that fuel can be rated for combustion instability using the same techniques as previously used for LOX/hydrogen. These techniques included fuel temperature ramping and stability bomb tests. The hot fire program probed the combustion behavior of methane from ambient to subambient temperatures. Very interesting results were obtained from this program that have potential importance to future LOX/methane development programs. A very thorough and carefully reasoned documentation of the experimental data obtained is contained. The hot fire test logic and the associated tests are discussed. Subscale performance and stability rating testing was accomplished using 40,000 lb. thrust class hardware. Stability rating tests used both bombs and fuel temperature ramping techniques. The test program was successful in generating data for the evaluation of the methane stability characteristics relative to hydrogen and to anchor stability models. Data correlations, performance analysis, stability analyses, and key stability margin enhancement parameters are discussed.

Towards optical brain imaging: getting light through a bone

NASA Astrophysics Data System (ADS)

Thompson, J. V.; Hokr, B. H.; Nodurft, D. T.; Yakovlev, V. V.

2018-06-01

Optical imaging and detection in biological samples is severely limited by scattering effects. In particular, optical techniques for measuring conditions beneath the skull and within the bone marrow hold significant promise when it comes to speed, sensitivity and specificity. However, the strong optical scattering due to bone hinders the realization of these methods. In this article, we propose a technique to enhance the transmittance of light through bone. This is achieved by injecting light below the top surface of the bone and utilizing multiple scattering to increase transmittance. This technique suggests that enhancements of 2-6 times may be realized by injection of light 1 mm below the surface of the bone. By enhancing the transmittance of light through bone, we will greatly improve our ability to utilize optical methods to better understand and diagnose conditions within biological media.

Quantum enhanced feedback cooling of a mechanical oscillator using nonclassical light.

PubMed

Schäfermeier, Clemens; Kerdoncuff, Hugo; Hoff, Ulrich B; Fu, Hao; Huck, Alexander; Bilek, Jan; Harris, Glen I; Bowen, Warwick P; Gehring, Tobias; Andersen, Ulrik L

2016-11-29

Laser cooling is a fundamental technique used in primary atomic frequency standards, quantum computers, quantum condensed matter physics and tests of fundamental physics, among other areas. It has been known since the early 1990s that laser cooling can, in principle, be improved by using squeezed light as an electromagnetic reservoir; while quantum feedback control using a squeezed light probe is also predicted to allow improved cooling. Here we show the implementation of quantum feedback control of a micro-mechanical oscillator using squeezed probe light. This allows quantum-enhanced feedback cooling with a measurement rate greater than it is possible with classical light, and a consequent reduction in the final oscillator temperature. Our results have significance for future applications in areas ranging from quantum information networks, to quantum-enhanced force and displacement measurements and fundamental tests of macroscopic quantum mechanics.

Slow-light enhanced subwavelength plasmonic waveguide refractive index sensors.

PubMed

Huang, Yin; Min, Changjun; Dastmalchi, Pouya; Veronis, Georgios

2015-06-01

We introduce slow-light enhanced subwavelength scale refractive index sensors which consist of a plasmonic metal-dielectric-metal (MDM) waveguide based slow-light system sandwiched between two conventional MDM waveguides. We first consider a MDM waveguide with small width structrue for comparison, and then consider two MDM waveguide based slow light systems: a MDM waveguide side-coupled to arrays of stub resonators system and a MDM waveguide side-coupled to arrays of double-stub resonators system. We find that, as the group velocity decreases, the sensitivity of the effective index of the waveguide mode to variations of the refractive index of the fluid filling the sensors as well as the sensitivities of the reflection and transmission coefficients of the waveguide mode increase. The sensing characteristics of the slow-light waveguide based sensor structures are systematically analyzed. We show that the slow-light enhanced sensors lead to not only 3.9 and 3.5 times enhancements in the refractive index sensitivity, and therefore in the minimum detectable refractive index change, but also to 2 and 3 times reductions in the required sensing length, respectively, compared to a sensor using a MDM waveguide with small width structure.

Enhanced light extraction from free-standing InGaN/GaN light emitters using bio-inspired backside surface structuring.

PubMed

Pynn, Christopher D; Chan, Lesley; Lora Gonzalez, Federico; Berry, Alex; Hwang, David; Wu, Haoyang; Margalith, Tal; Morse, Daniel E; DenBaars, Steven P; Gordon, Michael J

2017-07-10

Light extraction from InGaN/GaN-based multiple-quantum-well (MQW) light emitters is enhanced using a simple, scalable, and reproducible method to create hexagonally close-packed conical nano- and micro-scale features on the backside outcoupling surface. Colloidal lithography via Langmuir-Blodgett dip-coating using silica masks (d = 170-2530 nm) and Cl 2 /N 2 -based plasma etching produced features with aspect ratios of 3:1 on devices grown on semipolar GaN substrates. InGaN/GaN MQW structures were optically pumped at 266 nm and light extraction enhancement was quantified using angle-resolved photoluminescence. A 4.8-fold overall enhancement in light extraction (9-fold at normal incidence) relative to a flat outcoupling surface was achieved using a feature pitch of 2530 nm. This performance is on par with current photoelectrochemical (PEC) nitrogen-face roughening methods, which positions the technique as a strong alternative for backside structuring of c-plane devices. Also, because colloidal lithography functions independently of GaN crystal orientation, it is applicable to semipolar and nonpolar GaN devices, for which PEC roughening is ineffective.

Note: a novel vacuum ultraviolet light source assembly with aluminum-coated electrodes for enhancing the ionization efficiency of photoionization mass spectrometry.

PubMed

Zhu, Zhixiang; Wang, Jian; Qiu, Keqing; Liu, Chengyuan; Qi, Fei; Pan, Yang

2014-04-01

A novel vacuum ultraviolet (VUV) light source assembly (VUVLSA) for enhancing the ionization efficiency of photoionization mass spectrometer has been described. The VUVLSA composes of a Krypton lamp and a pair of disk electrodes with circular center cavities. The two interior surfaces that face the photoionization region were aluminum-coated. VUV light can be reflected back and forth in the photoionization region between the electrodes, thus the photoionization efficiency can be greatly enhanced. The performances of two different shaped electrodes, the coated double flat electrodes (DFE), and double conical electrodes, were studied. We showed that the signal amplification of coated DFE is around 4 times higher than that of uncoated electrodes without VUV light reflection. The relationship between the pressure of ionization chamber and mass signal enhancement has also been studied.

Enhanced optical output power of blue light-emitting diodes with quasi-aligned gold nanoparticles.

PubMed

Jin, Yuanhao; Li, Qunqing; Li, Guanhong; Chen, Mo; Liu, Junku; Zou, Yuan; Jiang, Kaili; Fan, Shoushan

2014-01-06

The output power of the light from GaN-based light-emitting diodes (LEDs) was enhanced by fabricating gold (Au) nanoparticles on the surface of p-GaN. Quasi-aligned Au nanoparticle arrays were prepared by depositing Au thin film on an aligned suspended carbon nanotube thin film surface and then putting the Au-CNT system on the surface of p-GaN and thermally annealing the sample. The size and position of the Au nanoparticles were confined by the carbon nanotube framework, and no other additional residual Au was distributed on the surface of the p-GaN substrate. The output power of the light from the LEDs with Au nanoparticles was enhanced by 55.3% for an injected current of 100 mA with the electrical property unchanged compared with the conventional planar LEDs. The enhancement may originate from the surface plasmon effect and scattering effect of the Au nanoparticles.

STM-induced light emission enhanced by weakly coupled organic ad-layers

NASA Astrophysics Data System (ADS)

Cottin, M. C.; Ekici, E.; Bobisch, C. A.

2018-03-01

We analyze the light emission induced by the tunneling current flowing in a scanning tunneling microscopy experiment. In particular, we study the influence of organic ad-layers on the light emission on the initial monolayer of bismuth (Bi) on Cu(111) in comparison to the well-known case of organic ad-layers on Ag(111). On the Bi/Cu(111)-surface, we find that the scanning tunneling microscopy-induced light emission is considerably enhanced if an organic layer, e.g., the fullerene C60 or the perylene derivate perylene-tetracarboxylic-dianhydride, is introduced into the tip-sample junction. The enhancement can be correlated with a peculiarly weak interaction between the adsorbed molecules and the underlying Bi/Cu(111) substrate as compared to the Ag(111) substrate. This allows us to efficiently enhance and tune the coupling of the tunneling current to localized excitations of the tip-sample junction, which in turn couple to radiative decay channels.

Perfect absorption in nanotextured thin films via Anderson-localized photon modes

NASA Astrophysics Data System (ADS)

Aeschlimann, Martin; Brixner, Tobias; Differt, Dominik; Heinzmann, Ulrich; Hensen, Matthias; Kramer, Christian; Lükermann, Florian; Melchior, Pascal; Pfeiffer, Walter; Piecuch, Martin; Schneider, Christian; Stiebig, Helmut; Strüber, Christian; Thielen, Philip

2015-10-01

The enhancement of light absorption in absorber layers is crucial in a number of applications, including photovoltaics and thermoelectrics. The efficient use of natural resources and physical constraints such as limited charge extraction in photovoltaic devices require thin but efficient absorbers. Among the many different strategies used, light diffraction and light localization at randomly nanotextured interfaces have been proposed to improve absorption. Although already exploited in commercial devices, the enhancement mechanism for devices with nanotextured interfaces is still subject to debate. Using coherent two-dimensional nanoscopy and coherent light scattering, we demonstrate the existence of localized photonic states in nanotextured amorphous silicon layers as used in commercial thin-film solar cells. Resonant absorption in these states accounts for the enhanced absorption in the long-wavelength cutoff region. Our observations establish that Anderson localization—that is, strong localization—is a highly efficient resonant absorption enhancement mechanism offering interesting opportunities for the design of efficient future absorber layers.

Progress and Perspectives of Plasmon-Enhanced Solar Energy Conversion.

PubMed

Cushing, Scott K; Wu, Nianqiang

2016-02-18

Plasmonics allows extraordinary control of light, making it attractive for application in solar energy harvesting. In metal-semiconductor heterojunctions, plasmons can enhance photoconversion in the semiconductor via three mechanisms, including light trapping, hot electron/hole transfer, and plasmon-induced resonance energy transfer (PIRET). To understand the plasmonic enhancement, the metal's geometry, constituent metal, and interface must be viewed in terms of the effects on the plasmon's dephasing and decay route. To simplify design of plasmonic metal-semiconductor heterojunctions for high-efficiency solar energy conversion, the parameters controlling the plasmonic enhancement can be distilled to the dephasing time. The plasmonic geometry can then be further refined to optimize hot carrier transfer, PIRET, or light trapping.

Non-plasmonic nanoantennas for surface enhanced spectroscopies with ultra-low heat conversion

PubMed Central

Caldarola, Martín; Albella, Pablo; Cortés, Emiliano; Rahmani, Mohsen; Roschuk, Tyler; Grinblat, Gustavo; Oulton, Rupert F.; Bragas, Andrea V.; Maier, Stefan A.

2015-01-01

Nanoplasmonics has recently revolutionized our ability to control light on the nanoscale. Using metallic nanostructures with tailored shapes, it is possible to efficiently focus light into nanoscale field ‘hot spots'. High field enhancement factors have been achieved in such optical nanoantennas, enabling transformative science in the areas of single molecule interactions, highly enhanced nonlinearities and nanoscale waveguiding. Unfortunately, these large enhancements come at the price of high optical losses due to absorption in the metal, severely limiting real-world applications. Via the realization of a novel nanophotonic platform based on dielectric nanostructures to form efficient nanoantennas with ultra-low light-into-heat conversion, here we demonstrate an approach that overcomes these limitations. We show that dimer-like silicon-based single nanoantennas produce both high surface enhanced fluorescence and surface enhanced Raman scattering, while at the same time generating a negligible temperature increase in their hot spots and surrounding environments. PMID:26238815

Non-plasmonic nanoantennas for surface enhanced spectroscopies with ultra-low heat conversion.

PubMed

Caldarola, Martín; Albella, Pablo; Cortés, Emiliano; Rahmani, Mohsen; Roschuk, Tyler; Grinblat, Gustavo; Oulton, Rupert F; Bragas, Andrea V; Maier, Stefan A

2015-08-04

Nanoplasmonics has recently revolutionized our ability to control light on the nanoscale. Using metallic nanostructures with tailored shapes, it is possible to efficiently focus light into nanoscale field 'hot spots'. High field enhancement factors have been achieved in such optical nanoantennas, enabling transformative science in the areas of single molecule interactions, highly enhanced nonlinearities and nanoscale waveguiding. Unfortunately, these large enhancements come at the price of high optical losses due to absorption in the metal, severely limiting real-world applications. Via the realization of a novel nanophotonic platform based on dielectric nanostructures to form efficient nanoantennas with ultra-low light-into-heat conversion, here we demonstrate an approach that overcomes these limitations. We show that dimer-like silicon-based single nanoantennas produce both high surface enhanced fluorescence and surface enhanced Raman scattering, while at the same time generating a negligible temperature increase in their hot spots and surrounding environments.

A comparison of honey bee-collected pollen from working agricultural lands using light microscopy and ITS metabarcoding

USGS Publications Warehouse

Smart, Matthew; Cornman, Robert S.; Iwanowicz, Deborah; McDermott-Kubeczko, Margaret; Pettis, Jeff S; Spivak, Marla S; Otto, Clint R.

2017-01-01

Taxonomic identification of pollen has historically been accomplished via light microscopy but requires specialized knowledge and reference collections, particularly when identification to lower taxonomic levels is necessary. Recently, next-generation sequencing technology has been used as a cost-effective alternative for identifying bee-collected pollen; however, this novel approach has not been tested on a spatially or temporally robust number of pollen samples. Here, we compare pollen identification results derived from light microscopy and DNA sequencing techniques with samples collected from honey bee colonies embedded within a gradient of intensive agricultural landscapes in the Northern Great Plains throughout the 2010–2011 growing seasons. We demonstrate that at all taxonomic levels, DNA sequencing was able to discern a greater number of taxa, and was particularly useful for the identification of infrequently detected species. Importantly, substantial phenological overlap did occur for commonly detected taxa using either technique, suggesting that DNA sequencing is an appropriate, and enhancing, substitutive technique for accurately capturing the breadth of bee-collected species of pollen present across agricultural landscapes. We also show that honey bees located in high and low intensity agricultural settings forage on dissimilar plants, though with overlap of the most abundantly collected pollen taxa. We highlight practical applications of utilizing sequencing technology, including addressing ecological issues surrounding land use, climate change, importance of taxa relative to abundance, and evaluating the impact of conservation program habitat enhancement efforts.

High definition plus colonoscopy combined with i-scan tone enhancement vs. high definition colonoscopy for colorectal neoplasia: A randomized trial.

PubMed

Hoffman, Arthur; Loth, Linn; Rey, Johannes Wilhelm; Rahman, Fareed; Goetz, Martin; Hansen, Torsten; Tresch, Achim; Niederberger, Theresa; Galle, Peter Robert; Kiesslich, Ralf

2014-11-01

High definition endoscopy is the accepted standard in colonoscopy. However, an important problem is missed polyps. Our objective was to assess the additional adenoma detection rate between high definition colonoscopy with tone enhancement (digital chromoendoscopy) vs. white light high definition colonoscopy. In this prospective randomized trial patients were included to undergo a tandem colonoscopy. The first exam was a white light colonoscopy with removal of all visualized polyps. The second examination was randomly assigned in a 1:1 ratio as either again white light colonoscopy (Group A) or colonoscopy with tone enhancement (Group B). Primary endpoint was the adenoma detection rate during the second withdrawal (sample size calculation - 40 per group). 67 lesions (Group A: n=34 vs. Group B: n=33) in 80 patients (mean age 61 years, male 64%) were identified on the first colonoscopy. The second colonoscopy detected 78 additional lesions: n=60 with tone enhancement vs. n=18 with white light endoscopy (p<0.001). Tone enhancement found more additional adenomas (A n=20 vs. B n=6, p=0.006) and identified significantly more missed adenomas per subject (0.5 vs. 0.15, p=0.006). High definition plus colonoscopy with tone enhancement detected more adenomas missed by white light colonoscopy. Copyright © 2014 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Enhanced coupling of light into a turbid medium through microscopic interface engineering

PubMed Central

Thompson, Jonathan V.; Hokr, Brett H.; Kim, Wihan; Ballmann, Charles W.; Applegate, Brian E.; Jo, Javier; Yamilov, Alexey; Cao, Hui; Scully, Marlan O.; Yakovlev, Vladislav V.

2017-01-01

There are many optical detection and sensing methods used today that provide powerful ways to diagnose, characterize, and study materials. For example, the measurement of spontaneous Raman scattering allows for remote detection and identification of chemicals. Many other optical techniques provide unique solutions to learn about biological, chemical, and even structural systems. However, when these systems exist in a highly scattering or turbid medium, the optical scattering effects reduce the effectiveness of these methods. In this article, we demonstrate a method to engineer the geometry of the optical interface of a turbid medium, thereby drastically enhancing the coupling efficiency of light into the material. This enhanced optical coupling means that light incident on the material will penetrate deeper into (and through) the medium. It also means that light thus injected into the material will have an enhanced interaction time with particles contained within the material. These results show that, by using the multiple scattering of light in a turbid medium, enhanced light–matter interaction can be achieved; this has a direct impact on spectroscopic methods such as Raman scattering and fluorescence detection in highly scattering regimes. Furthermore, the enhanced penetration depth achieved by this method will directly impact optical techniques that have previously been limited by the inability to deposit sufficient amounts of optical energy below or through highly scattering layers. PMID:28701381

Synthesis and characterization of g-C{sub 3}N{sub 4}/Cu{sub 2}O composite catalyst with enhanced photocatalytic activity under visible light irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Biyu; Zhang, Shengsen; Yang, Siyuan

2014-08-15

The prepared g-C{sub 3}N{sub 4}/Cu{sub 2}O composite exhibited the enhanced photocatalytic activity under visible-light irradiation due to the stronger ability in separation of electron–hole pairs, which was proven by the transient photocurrent measurement. - Highlights: • The coupled Cu{sub 2}O with g-C{sub 3}N{sub 4} of narrow-band-gap semiconductor has been designed. • g-C{sub 3}N{sub 4}/Cu{sub 2}O is prepared via an alcohol-aqueous based on chemical precipitation method. • g-C{sub 3}N{sub 4}/Cu{sub 2}O exhibits the enhanced photocatalytic activity under visible-light. • The enhanced photocatalytic activity is proven by the transient photocurrent test. • A mechanism for the visible-light-driven photocatalysis of g-C{sub 3}N{sub 4}/Cu{submore » 2}O is revealed. - Abstract: To overcome the drawback of low photocatalytic efficiency brought by electron–hole pairs recombination and narrow photo-response range, a novel g-C{sub 3}N{sub 4}/Cu{sub 2}O composite photocatalyst was designed and prepared successfully. Compared with bare Cu{sub 2}O and g-C{sub 3}N{sub 4}, the g-C{sub 3}N{sub 4}/Cu{sub 2}O composite exhibited significantly enhanced photocatalytic activity for acid orange-II (AO-II) degradation under visible light irradiation. Based on energy band positions, the mechanism of enhanced visible-light photocatalytic activity was proposed.« less

Exposure to blue light during lunch break: effects on autonomic arousal and behavioral alertness.

PubMed

Yuda, Emi; Ogasawara, Hiroki; Yoshida, Yutaka; Hayano, Junichiro

2017-07-11

Exposures to melanopsin-stimulating (melanopic) component-rich blue light enhance arousal level. We examined their effects in office workers. Eight healthy university office workers were exposed to blue and orange lights for 30 min during lunch break on different days. We compared the effects of light color on autonomic arousal level assessed by heart rate variability (HRV) and behavioral alertness by psychomotor vigilance tests (PVT). Heart rate was higher and high-frequency (HF, 0.150.45 Hz) power of HRV was lower during exposure to the blue light than to orange light. No significant difference with light color was observed, however, in any HRV indices during PVT or in PVT performance after light exposure. Exposure to blue light during lunch break, compared with that to orange light, enhances autonomic arousal during exposure, but has no sustained effect on autonomic arousal or behavioral alertness after exposure.

Enhanced photoluminescence intensity by modifying the surface nanostructure of Nd3+-doped (Pb, La)(Zr, Ti)O3 ceramics.

PubMed

Xu, Long; Zhang, Jingwen; Zhao, Hua; Sun, Haibin; Xu, Caixia

2017-09-01

Quasi-period cylindrical nanostructures with both diameters and intervals of about 100 nm are manufactured on the surfaces of Nd 3+ -doped lanthanum lead zirconate titanate ceramics by femtosecond laser irradiation under SF 6 atmosphere. A light-emission enhancement of more than 20 times is investigated, accompanied by an extremely long trailing-off time of light emission and lower threshold. A specific polarization state of the light emission is achieved and tuned by changing the incident regions of the pumping source. The increased absorption coefficient of the specimen is discussed based on multiple scattering and weak localization of light. In addition, both the scatterers provided by the laser-machined nanostructure and the recurrent photoinduced trapping and re-excitation process participated in the enhancement of the light emission. This Letter offers new insight to improve the luminescence property of laser materials, as well as to broaden the range of exploring the weak localization of light and random lasers.

Colour Light And Wellbeing: A Case Study Of M Mall 020 George Town, Penang Island

NASA Astrophysics Data System (ADS)

Aqbar Zakaria, Safial; Yii Rou, Ng; Zhi En, Hoi; Iyian, Tai

2017-12-01

Contrary to popular belief, the brightest light or the most colourful light makes good lighting design. However, what makes a good lighting design in interior space is an impeccable composite of art and science. With the application of good lighting design, it can produce an impressive result from enhancing the aesthetic of architectural elements to conveying the right type of ambiance of the interiors. This research intends to address the crucial issues regarding the ways in which lighting designers can communicate the benefits of good lighting and to create a better awareness to users. The objectives of this paper are to outline and explore the features of good and poor lighting design in M Mall O2O based on the lighting design language and profession. The results of this research are mainly qualitative in nature, supported by the professional lighting designers on the definitions of good lighting, personal observation and visual data which were taken in George Town, Penang Island. The case studies on good and poor lighting portrayed in this mall were used as examples to scrutinize the issues raised herein. To achieve the optimum lighting design, a joint approach of focusing on the artistic flair brought forth by lighting and more scientific effort on the calculation levels of lights is crucial. Different functionality requires a different amount of attention on either approach. In conclusion, a good lighting design must be able to enhance the atmosphere and also enrich the quality of the interior architecture. Apart from that, a good lighting design should have good distribution of brightness levels, contrast and different colour temperatures to enhance characters of the interior spaces without neglecting the health and wellbeing aspects.

Highly efficient temperature-induced visible light photocatalytic hydrogen production

NASA Astrophysics Data System (ADS)

Han, Bing

Photocatalysis is the acceleration of photoreaction in presence of a photocatalyst. Semiconductor photocatalysis has obtained much attention as a potential solution to the worldwide energy storage due to its promising ability to directly convert solar energy into chemical fuels. This dissertation research mainly employ three approaches to enhance photocatalytic activities, which includes (I) Modifying semiconductor nanomaterials for visible and near-IR light absorption; (II) Synthesis of light-diffuse-reflection-surface of SiO2 substrate to utilize scattered light; and (III) design of a hybrid system that combines light and heat to enhance visible light photocatalytic activity. Those approaches were applied to two systems: (1) hydrogen production from water; (2) carbon dioxide reforming of methane. The activity of noble metals such as platinum were investigated as co-catalysts and cheap earth abundant catalysts as alternatives to reduce cost were also developed. Stability, selectivity, mechanism were investigated. Great enhancement of visible light activity over a series of semiconductors/heterostructures were observed. Such extraordinary performance of artificial photosynthetic hydrogen production system would provide a novel approach for the utilization of solar energy for chemical fuel production.

Blue enhanced light sources: opportunities and risks

NASA Astrophysics Data System (ADS)

Lang, Dieter

2012-03-01

Natural daylight is characterized by high proportions of blue light. By proof of a third type of photoreceptor in the human eye which is only sensitive in this spectral region and by subsequent studies it has become obvious that these blue proportions are essential for human health and well being. In various studies beneficial effects of indoor lighting with higher blue spectral proportions have been proven. On the other hand with increasing use of light sources having enhanced blue light for indoor illumination questions are arising about potential health risks attributed to blue light. Especially LED are showing distinct emission characteristics in the blue. Recently the French agency for food, environmental and occupational health & safety ANSES have raised the question on health issues related to LED light sources and have claimed to avoid use of LED for lighting in schools. In this paper parameters which are relevant for potential health risks will be shown and their contribution to risk factors will quantitatively be discussed. It will be shown how to differentiate between photometric parameters for assessment of beneficial as well as hazardous effects. Guidelines will be discussed how blue enhanced light sources can be used in applications to optimally support human health and well being and simultaneously avoid any risks attributed to blue light by a proper design of lighting parameters. In the conclusion it will be shown that no inherent health risks are related to LED lighting with a proper lighting design.

UmUTracker: A versatile MATLAB program for automated particle tracking of 2D light microscopy or 3D digital holography data

NASA Astrophysics Data System (ADS)

Zhang, Hanqing; Stangner, Tim; Wiklund, Krister; Rodriguez, Alvaro; Andersson, Magnus

2017-10-01

We present a versatile and fast MATLAB program (UmUTracker) that automatically detects and tracks particles by analyzing video sequences acquired by either light microscopy or digital in-line holographic microscopy. Our program detects the 2D lateral positions of particles with an algorithm based on the isosceles triangle transform, and reconstructs their 3D axial positions by a fast implementation of the Rayleigh-Sommerfeld model using a radial intensity profile. To validate the accuracy and performance of our program, we first track the 2D position of polystyrene particles using bright field and digital holographic microscopy. Second, we determine the 3D particle position by analyzing synthetic and experimentally acquired holograms. Finally, to highlight the full program features, we profile the microfluidic flow in a 100 μm high flow chamber. This result agrees with computational fluid dynamic simulations. On a regular desktop computer UmUTracker can detect, analyze, and track multiple particles at 5 frames per second for a template size of 201 ×201 in a 1024 × 1024 image. To enhance usability and to make it easy to implement new functions we used object-oriented programming. UmUTracker is suitable for studies related to: particle dynamics, cell localization, colloids and microfluidic flow measurement. Program Files doi : http://dx.doi.org/10.17632/fkprs4s6xp.1 Licensing provisions : Creative Commons by 4.0 (CC by 4.0) Programming language : MATLAB Nature of problem: 3D multi-particle tracking is a common technique in physics, chemistry and biology. However, in terms of accuracy, reliable particle tracking is a challenging task since results depend on sample illumination, particle overlap, motion blur and noise from recording sensors. Additionally, the computational performance is also an issue if, for example, a computationally expensive process is executed, such as axial particle position reconstruction from digital holographic microscopy data. Versatile robust tracking programs handling these concerns and providing a powerful post-processing option are significantly limited. Solution method: UmUTracker is a multi-functional tool to extract particle positions from long video sequences acquired with either light microscopy or digital holographic microscopy. The program provides an easy-to-use graphical user interface (GUI) for both tracking and post-processing that does not require any programming skills to analyze data from particle tracking experiments. UmUTracker first conduct automatic 2D particle detection even under noisy conditions using a novel circle detector based on the isosceles triangle sampling technique with a multi-scale strategy. To reduce the computational load for 3D tracking, it uses an efficient implementation of the Rayleigh-Sommerfeld light propagation model. To analyze and visualize the data, an efficient data analysis step, which can for example show 4D flow visualization using 3D trajectories, is included. Additionally, UmUTracker is easy to modify with user-customized modules due to the object-oriented programming style Additional comments: Program obtainable from https://sourceforge.net/projects/umutracker/

A synthetic genetic edge detection program.

PubMed

Tabor, Jeffrey J; Salis, Howard M; Simpson, Zachary Booth; Chevalier, Aaron A; Levskaya, Anselm; Marcotte, Edward M; Voigt, Christopher A; Ellington, Andrew D

2009-06-26

Edge detection is a signal processing algorithm common in artificial intelligence and image recognition programs. We have constructed a genetically encoded edge detection algorithm that programs an isogenic community of E. coli to sense an image of light, communicate to identify the light-dark edges, and visually present the result of the computation. The algorithm is implemented using multiple genetic circuits. An engineered light sensor enables cells to distinguish between light and dark regions. In the dark, cells produce a diffusible chemical signal that diffuses into light regions. Genetic logic gates are used so that only cells that sense light and the diffusible signal produce a positive output. A mathematical model constructed from first principles and parameterized with experimental measurements of the component circuits predicts the performance of the complete program. Quantitatively accurate models will facilitate the engineering of more complex biological behaviors and inform bottom-up studies of natural genetic regulatory networks.

A Synthetic Genetic Edge Detection Program

PubMed Central

Tabor, Jeffrey J.; Salis, Howard; Simpson, Zachary B.; Chevalier, Aaron A.; Levskaya, Anselm; Marcotte, Edward M.; Voigt, Christopher A.; Ellington, Andrew D.

2009-01-01

Summary Edge detection is a signal processing algorithm common in artificial intelligence and image recognition programs. We have constructed a genetically encoded edge detection algorithm that programs an isogenic community of E.coli to sense an image of light, communicate to identify the light-dark edges, and visually present the result of the computation. The algorithm is implemented using multiple genetic circuits. An engineered light sensor enables cells to distinguish between light and dark regions. In the dark, cells produce a diffusible chemical signal that diffuses into light regions. Genetic logic gates are used so that only cells that sense light and the diffusible signal produce a positive output. A mathematical model constructed from first principles and parameterized with experimental measurements of the component circuits predicts the performance of the complete program. Quantitatively accurate models will facilitate the engineering of more complex biological behaviors and inform bottom-up studies of natural genetic regulatory networks. PMID:19563759

New light Higgs boson and short-baseline neutrino anomalies

NASA Astrophysics Data System (ADS)

Asaadi, J.; Church, E.; Guenette, R.; Jones, B. J. P.; Szelc, A. M.

2018-04-01

The low-energy excesses observed by the MiniBooNE experiment have, to date, defied a convincing explanation under the standard model even with accommodation for nonzero neutrino mass. In this paper we explore a new oscillation mechanism to explain these anomalies, invoking a light neutrinophilic Higgs boson, conceived to induce a low Dirac neutrino mass in accord with experimental limits. Beam neutrinos forward scattering off of a locally overdense relic neutrino background give rise to a novel matter effect with an energy-specific resonance. An enhanced oscillation around this resonance peak produces flavor transitions which are highly consistent with the MiniBooNE neutrino- and antineutrino-mode data sets. The model provides substantially improved χ2 values beyond either the no-oscillation hypothesis or the more commonly explored 3 +1 sterile neutrino hypothesis. This mechanism would introduce distinctive signatures at each baseline in the upcoming short-baseline neutrino program at Fermilab, presenting opportunities for further exploration.

Photocatalytic Degradation of DIPA Using Bimetallic Cu-Ni/TiO2 Photocatalyst under Visible Light Irradiation

PubMed Central

Bustam, Mohamad Azmi; Chong, Fai Kait; Man, Zakaria B.; Khan, Muhammad Saqib; Shariff, Azmi M.

2014-01-01

Bimetallic Cu-Ni/TiO2 photocatalysts were synthesized using wet impregnation (WI) method with TiO2 (Degussa-P25) as support and calcined at different temperatures (180, 200, and 300°C) for the photodegradation of DIPA under visible light. The photocatalysts were characterized using TGA, FESEM, UV-Vis diffuse reflectance spectroscopy, fourier transform infrared spectroscopy (FTIR) and temperature programmed reduction (TPR). The results from the photodegradation experiments revealed that the Cu-Ni/TiO2 photocatalysts exhibited much higher photocatalytic activities compared to bare TiO2. It was found that photocatalyst calcined at 200°C had the highest photocatalyst activities with highest chemical oxygen demand (COD) removal (86.82%). According to the structural and surface analysis, the enhanced photocatalytic activity could be attributed to its strong absorption into the visible region and high metal dispersion. PMID:25105158

dxz/yz subband structure and Chiral Orbital Angular Momentum of Nb doped SrTiO3 surface states

NASA Astrophysics Data System (ADS)

Soltani, Shoresh; Cho, Soohyun; Ryu, Hanyoung; Han, Garam; Kim, Timur; Hoesch, Moritz; Kim, Changyoung

Using angle resolved photoemission spectroscopy (ARPES), we investigate subband structure and chiral orbital angular momentum (OAM) texture on the surface of lightly electron doped SrTiO3 single crystals. Our linearly polarized light ARPES data taken with 51 eV photons, reveal additional subbands for out-of-plane dxz/yzorbitals in addition to the previously reported ones. Our CD-ARPES data reveal a chiral OAM structure which we use as a clue to explain the origin of linear Rashba-like surface band splitting of Ti 3d t2g orbitals. The observed CD signal is enhanced near crossing points, where different orbitals hybridize, compatible with a linear Rashba-like surface band splitting. The work was supported by IBS-R009-G2. S.S., S.C., H.Y. and G. H. acknowledge were supported by Yonsei university, BK21 program.

Heat Shock–Induced Fluctuations in Clock and Light Signaling Enhance Phytochrome B–Mediated Arabidopsis Deetiolation[C][W

PubMed Central

Karayekov, Elizabeth; Sellaro, Romina; Legris, Martina; Yanovsky, Marcelo J.; Casal, Jorge J.

2013-01-01

Moderately warm constant ambient temperatures tend to oppose light signals in the control of plant architecture. By contrast, here we show that brief heat shocks enhance the inhibition of hypocotyl growth induced by light perceived by phytochrome B in deetiolating Arabidopsis thaliana seedlings. In darkness, daily heat shocks transiently increased the expression of PSEUDO-RESPONSE REGULATOR7 (PRR7) and PRR9 and markedly enhanced the amplitude of the rhythms of LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED1 (CCA1) expression. In turn, these rhythms gated the hypocotyl response to red light, in part by changing the expression of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5. After light exposure, heat shocks also reduced the nuclear abundance of CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) and increased the abundance of its target ELONGATED HYPOCOTYL5 (HY5). The synergism between light and heat shocks was deficient in the prr7 prr9, lhy cca1, pif4 pif5, cop1, and hy5 mutants. The evening element (binding site of LHY and CCA1) and G-box promoter motifs (binding site of PIFs and HY5) were overrepresented among genes with expression controlled by both heat shock and red light. The heat shocks experienced by buried seedlings approaching the surface of the soil prepare the seedlings for the impending exposure to light by rhythmically lowering LHY, CCA1, PIF4, and PIF5 expression and by enhancing HY5 stability. PMID:23933882

Blue-Enriched White Light Enhances Physiological Arousal But Not Behavioral Performance during Simulated Driving at Early Night

PubMed Central

Rodríguez-Morilla, Beatriz; Madrid, Juan A.; Molina, Enrique; Correa, Angel

2017-01-01

Vigilance usually deteriorates over prolonged driving at non-optimal times of day. Exposure to blue-enriched light has shown to enhance arousal, leading to behavioral benefits in some cognitive tasks. However, the cognitive effects of long-wavelength light have been less studied and its effects on driving performance remained to be addressed. We tested the effects of a blue-enriched white light (BWL) and a long-wavelength orange light (OL) vs. a control condition of dim light on subjective, physiological and behavioral measures at 21:45 h. Neurobehavioral tests included the Karolinska Sleepiness Scale and subjective mood scale, recording of distal-proximal temperature gradient (DPG, as index of physiological arousal), accuracy in simulated driving and reaction time in the auditory psychomotor vigilance task. The results showed that BWL decreased the DPG (reflecting enhanced arousal), while it did not improve reaction time or driving performance. Instead, blue light produced larger driving errors than OL, while performance in OL was stable along time on task. These data suggest that physiological arousal induced by light does not necessarily imply cognitive improvement. Indeed, excessive arousal might deteriorate accuracy in complex tasks requiring precision, such as driving. PMID:28690558

Slow light enhanced gas sensing in photonic crystals

NASA Astrophysics Data System (ADS)

Kraeh, Christian; Martinez-Hurtado, J. L.; Popescu, Alexandru; Hedler, Harry; Finley, Jonathan J.

2018-02-01

Infrared spectroscopy allows for highly selective and highly sensitive detection of gas species and concentrations. Conventional gas spectrometers are generally large and unsuitable for on-chip applications. Long absorption path lengths are usually required and impose a challenge for miniaturization. In this work, a gas spectrometer is developed consisting of a microtube photonic crystal structure. This structure of millimetric form factors minimizes the required absorption path length due to slow light effects. The microtube photonic crystal allows for strong transmission in the mid-infrared and, due to its large void space fraction, a strong interaction between light and gas molecules. As a result, enhanced absorption of light increases the gas sensitivity of the device. Slow light enhanced gas absorption by a factor of 5.8 in is experimentally demonstrated at 5400 nm. We anticipate small form factor gas sensors on silicon to be a starting point for on-chip gas sensing architectures.

Enhancing light emission in flexible AC electroluminescent devices by tetrapod-like zinc oxide whiskers.

PubMed

Wen, Li; Liu, Nishuang; Wang, Siliang; Zhang, Hui; Zhao, Wanqiu; Yang, Zhichun; Wang, Yumei; Su, Jun; Li, Luying; Long, Fei; Zou, Zhengguang; Gao, Yihua

2016-10-03

Flexible alternating current electroluminescent devices (ACEL) are more and more popular and widely used in liquid-crystal display back-lighting, large-scale architectural and decorative lighting due to their uniform light emission, low power consumption and high resolution. However, presently how to acquire high brightness under a certain voltage are confronted with challenges. Here, we demonstrate an electroluminescence (EL) enhancing strategy that tetrapod-like ZnO whiskers (T-ZnOw) are added into the bottom electrode of carbon nanotubes (CNTs) instead of phosphor layer in flexible ACEL devices emitting blue, green and orange lights, and the brightness is greatly enhanced due to the coupling between the T-ZnOw and ZnS phosphor dispersed in the flexible polydimethylsiloxane (PDMS) layer. This strategy provides a new routine for the development of high performance, flexible and large-area ACEL devices.

Evidence from Studies with Acifluorfen for Participation of a Flavin-Cytochrome Complex in Blue Light Photoreception for Phototropism of Oat Coleoptiles 12

PubMed Central

Leong, Ta-Yan; Briggs, Winslow R.

1982-01-01

The diphenyl ether acifluorfen enhances the blue light-induced absorbance change in Triton X100-solubilized crude membrane preparations from etiolated oat (Avena sativa L. cv. Lodi) coleoptiles. Enhancement of the spectral change is correlated with a change in rate of dark reoxidation of a b-type cytochrome. Similar, although smaller, enhancement was obtained with oxyfluorfen, nitrofen, and bifenox. Light-minus-dark difference spectra in the presence and absence of acifluorfen, and the dithionite-reduced-minus oxidized difference spectrum indicate that acifluorfen is acting specifically at a blue light-sensitive cytochrome-flavin complex. Sodium azide, a flavin inhibitor, decreases the light-induced absorbance change significantly, but does not affect the dark reoxidation of the cytochrome. Hence, it is acting on the light reaction, suggesting that the photoreceptor itself is a flavin. Acifluorfen sensitizes phototropism in dark-grown oat seedlings such that the first positive response occurs with blue light fluences as little as one-third of those required to elicit the same response in seedlings grown in the absence of the herbicide. Both this increase in sensitivity to light and the enhancement of the light-induced cytochrome reduction vary with the applied acifluorfen concentration in a similar manner. The herbicide is without effect either on elongation or on the geotropic response of dark-grown oat seedlings, indicating that acifluorfen is acting specifically close to, or at the photoreceptor end of, the stimulus-response chain. It seems likely that the flavin-cytochrome complex serves to transduce the light signal into curvature in phototropism in oats, with the flavin moiety itself serving as the photoreceptor. PMID:16662593

Visible red light enhances physiological anagen entry in vivo and has direct and indirect stimulative effects in vitro.

PubMed

Sheen, Yi-Shuan; Fan, Sabrina Mai-Yi; Chan, Chih-Chieh; Wu, Yueh-Feng; Jee, Shiou-Hwa; Lin, Sung-Jan

2015-01-01

Hair follicles are located at the interface of the external and internal environments and their cycling has been shown to be regulated by intra- and extra-follicular factors. The aim of this study is to examine whether or how hair follicles respond to visible light. We examined the effect of 3 mW red (630 nm, 1 J/cm(2)), 2 mW green (522 nm, 1 J/cm(2)), and 2 mW blue light (463 nm, 1 J/cm(2)) on telogen in mice for 3 weeks. The photobiologic effects of red light on cell proliferation of outer root sheath keratinocytes and dermal papilla cells were studied in vitro. We found that red light accelerated anagen entry faster than green and blue light in mice. Red light irradiation stimulated the proliferation of both outer root sheath keratinocytes and dermal papilla cells in a dose-dependent manner by promoting cell cycle progression. This stimulative effect was mediated via extracellular signal-regulated kinase phosphorylation in both cells. In a co-culture condition, dermal papilla cells irradiated by red light further enhanced keratinocyte proliferation, suggesting enhanced epithelial-mesenchymal interaction. In search for factors that mediated this paracrine effect, we found fibroblast growth factor 7 was upregulated in both mRNA and protein levels. The stimulative paracrine effect on keratinocytes was significantly inhibited by neutralizing antibody against fibroblast growth factor 7. These results suggest that hair follicles respond to visible light in vivo. Red light may promote physiological telogen to anagen transition by directly stimulating outer root sheath keratinocytes and indirectly by enhancing epithelial-mesenchymal interaction in vitro. © 2014 Wiley Periodicals, Inc.

Investigation of self-adaptive LED surgical lighting based on entropy contrast enhancing method

NASA Astrophysics Data System (ADS)

Liu, Peng; Wang, Huihui; Zhang, Yaqin; Shen, Junfei; Wu, Rengmao; Zheng, Zhenrong; Li, Haifeng; Liu, Xu

2014-05-01

Investigation was performed to explore the possibility of enhancing contrast by varying the spectral distribution (SPD) of the surgical lighting. The illumination scenes with different SPDs were generated by the combination of a self-adaptive white light optimization method and the LED ceiling system, the images of biological sample are taken by a CCD camera and then processed by an 'Entropy' based contrast evaluation model which is proposed specific for surgery occasion. Compared with the neutral white LED based and traditional algorithm based image enhancing methods, the illumination based enhancing method turns out a better performance in contrast enhancing and improves the average contrast value about 9% and 6%, respectively. This low cost method is simple, practicable, and thus may provide an alternative solution for the expensive visual facility medical instruments.

Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates.

PubMed

Pan, Jui-Wen; Tsai, Pei-Jung; Chang, Kao-Der; Chang, Yung-Yuan

2013-03-01

In this paper, we propose a method to analyze the light extraction efficiency (LEE) enhancement of a nanopatterned sapphire substrates (NPSS) light-emitting diode (LED) by comparing wave optics software with ray optics software. Finite-difference time-domain (FDTD) simulations represent the wave optics software and Light Tools (LTs) simulations represent the ray optics software. First, we find the trends of and an optimal solution for the LEE enhancement when the 2D-FDTD simulations are used to save on simulation time and computational memory. The rigorous coupled-wave analysis method is utilized to explain the trend we get from the 2D-FDTD algorithm. The optimal solution is then applied in 3D-FDTD and LTs simulations. The results are similar and the difference in LEE enhancement between the two simulations does not exceed 8.5% in the small LED chip area. More than 10(4) times computational memory is saved during the LTs simulation in comparison to the 3D-FDTD simulation. Moreover, LEE enhancement from the side of the LED can be obtained in the LTs simulation. An actual-size NPSS LED is simulated using the LTs. The results show a more than 307% improvement in the total LEE enhancement of the NPSS LED with the optimal solution compared to the conventional LED.

Microgravity Researchers to Investigate Nanotechnology

NASA Technical Reports Server (NTRS)

2000-01-01

Cadmium sulfide -- a semiconductor material -- can be grown in nanoclusters. Small molecules of cadmium sulfide, shown here, can be prepared by traditional chemical methods. However, if larger, more uniform nanoparticles of cadmium sulfide could be fabricated, they may be used to improve electronic devices such as light emitting diodes and diode lasers. Using a NASA grant, Dr. Jimmy Mays of the University of Alabama at Birmingham is studying whether microgravity will enhance the size and shape of a nanoparticle. This experiment is managed by the Microgravity Research Program Office at NASA's Marshall Spce Flight Center in Huntsville, AL. Photo credit: NASA/Marshall Space Flight Center

Microgravity

NASA Image and Video Library

2000-03-15

Cadmium sulfide -- a semiconductor material -- can be grown in nanoclusters. Small molecules of cadmium sulfide, shown here, can be prepared by traditional chemical methods. However, if larger, more uniform nanoparticles of cadmium sulfide could be fabricated, they may be used to improve electronic devices such as light emitting diodes and diode lasers. Using a NASA grant, Dr. Jimmy Mays of the University of Alabama at Birmingham is studying whether microgravity will enhance the size and shape of a nanoparticle. This experiment is managed by the Microgravity Research Program Office at NASA's Marshall Spce Flight Center in Huntsville, AL. Photo credit: NASA/Marshall Space Flight Center

Optical clearing of skin enhanced with hyaluronic acid for increased contrast of optoacoustic imaging

NASA Astrophysics Data System (ADS)

Liopo, Anton; Su, Richard; Tsyboulski, Dmitri A.; Oraevsky, Alexander A.

2016-08-01

Enhanced delivery of optical clearing agents (OCA) through skin may improve sensitivity of optical and optoacoustic (OA) methods of imaging, sensing, and monitoring. This report describes a two-step method for enhancement of light penetration through skin. Here, we demonstrate that topical application of hyaluronic acid (HA) improves skin penetration of hydrophilic and lipophilic OCA and thus enhances their performance. We examined the OC effect of 100% polyethylene and polypropylene glycols (PPGs) and their mixture after pretreatment by HA, and demonstrated significant increase in efficiency of light penetration through skin. Increased light transmission resulted in a significant increase of OA image contrast in vitro. Topical pretreatment of skin for about 30 min with 0.5% HA in aqueous solution offers effective delivery of low molecular weight OCA such as a mixture of PPG-425 and polyethylene glycol (PEG)-400. The developed approach of pretreatment by HA prior to application of clearing agents (PEG and PPG) resulted in a ˜47-fold increase in transmission of red and near-infrared light and significantly enhanced contrast of OA images.

Programmed near-infrared light-responsive drug delivery system for combined magnetic tumor-targeting magnetic resonance imaging and chemo-phototherapy.

PubMed

Feng, Qianhua; Zhang, Yuanyuan; Zhang, Wanxia; Hao, Yongwei; Wang, Yongchao; Zhang, Hongling; Hou, Lin; Zhang, Zhenzhong

2017-02-01

In this study, an intelligent drug delivery system was developed by capping doxorubicin (DOX)-loaded hollow mesoporous CuS nanoparticles (HMCuS NPs) with superparamagnetic iron oxide nanoparticles (IONPs). Under near infrared (NIR) light irradiation, the versatile HMCuS NPs could exploit the merits of both photothermal therapy (PTT) and photodynamic therapy (PDT) simultaneously. Herein, the multifunctional IONPs as gatekeeper with the enhanced capping efficiency were supposed to realize "zero premature release" and minimize the adverse side effects during the drug delivery in vivo. More importantly, the hybrid metal nanoplatform (HMCuS/DOX@IONP-PEG) allowed several emerging exceptional characteristics. Our studies have substantiated the hybrid nanoparticles possessed an enhanced PTT effect due to coupled plasmonic resonances with an elevated heat-generating capacity. Notably, an effective removal of IONP-caps occurred after NIR-induced photo-hyperthermia via weakening of the coordination interactions between HMCuS-NH 2 and IONPs, which suggested the feasibility of sophisticated controlled on-demand drug release upon exposing to NIR stimulus with spatial/temporal resolution. Benefiting from the favorable magnetic tumor targeting efficacy, the in vitro and in vivo experiments indicated a remarkable anti-tumor therapeutic efficacy under NIR irradiation, resulting from the synergistic combination of chemo-phototherapy. In addition, T 2 -weighted magnetic resonance imaging (MRI) contrast performance of IONPs provided the identification of cancerous lesions. Based on these findings, the well-designed drug delivery system via integration of programmed functions will provide knowledge for advancing multimodality theranostic strategy. As we all know, a series of shortcomings of conventional chemotherapy such as limited stability, rapid clearing and non-specific tumor targeting ability remain a significant challenge to achieve successful clinical therapeutic efficiency in cancer treatments. Fortunately, developing drug delivery system under the assistance of multifunctional nanocarries might be a great idea. For the first time, we proposed an intelligent drug delivery system by capping DOX-loaded hollow mesoporous CuS nanoparticles (HMCuS NPs) with multifunctional IONPs to integrate programmed functions including enhanced PTT effect, sophisticated controlled drug release, magnetic targeting property and MR imaging. The results showed HMCuS/DOX@IONP-PEG could significantly enhance anti-tumor therapeutic efficacy due to the synergistic combination of chemo-phototherapy. By this delicate design, we believe such smart and extreme versatile all-in-one drug delivery platform could arouse broad interests in the fields of biomaterials, nanotechnology, and drug delivery system. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Analysis of light extraction efficiency enhancement for thin-film-flip-chip InGaN quantum wells light-emitting diodes with GaN micro-domes.

PubMed

Zhao, Peng; Zhao, Hongping

2012-09-10

The enhancement of light extraction efficiency for thin-film flip-chip (TFFC) InGaN quantum wells (QWs) light-emitting diodes (LEDs) with GaN micro-domes on n-GaN layer was studied. The light extraction efficiency of TFFC InGaN QWs LEDs with GaN micro-domes were calculated and compared to that of the conventional TFFC InGaN QWs LEDs with flat surface. The three dimensional finite difference time domain (3D-FDTD) method was used to calculate the light extraction efficiency for the InGaN QWs LEDs emitting at 460nm and 550 nm, respectively. The effects of the GaN micro-dome feature size and the p-GaN layer thickness on the light extraction efficiency were studied systematically. Studies indicate that the p-GaN layer thickness is critical for optimizing the TFFC LED light extraction efficiency. Significant enhancement of the light extraction efficiency (2.5-2.7 times for λ(peak) = 460nm and 2.7-2.8 times for λ(peak) = 550nm) is achievable from TFFC InGaN QWs LEDs with optimized GaN micro-dome diameter and height.

Gap-Mode Surface-Plasmon-Enhanced Photoluminescence and Photoresponse of MoS2.

PubMed

Wu, Zhi-Qian; Yang, Jing-Liang; Manjunath, Nallappagar K; Zhang, Yue-Jiao; Feng, Si-Rui; Lu, Yang-Hua; Wu, Jiang-Hong; Zhao, Wei-Wei; Qiu, Cai-Yu; Li, Jian-Feng; Lin, Shi-Sheng

2018-05-22

2D materials hold great potential for designing novel electronic and optoelectronic devices. However, 2D material can only absorb limited incident light. As a representative 2D semiconductor, monolayer MoS 2 can only absorb up to 10% of the incident light in the visible, which is not sufficient to achieve a high optical-to-electrical conversion efficiency. To overcome this shortcoming, a "gap-mode" plasmon-enhanced monolayer MoS 2 fluorescent emitter and photodetector is designed by squeezing the light-field into Ag shell-isolated nanoparticles-Au film gap, where the confined electromagnetic field can interact with monolayer MoS 2 . With this gap-mode plasmon-enhanced configuration, a 110-fold enhancement of photoluminescence intensity is achieved, exceeding values reached by other plasmon-enhanced MoS 2 fluorescent emitters. In addition, a gap-mode plasmon-enhanced monolayer MoS 2 photodetector with an 880% enhancement in photocurrent and a responsivity of 287.5 A W -1 is demonstrated, exceeding previously reported plasmon-enhanced monolayer MoS 2 photodetectors. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

White LEDs and modules in chip-on-board technology for general lighting

NASA Astrophysics Data System (ADS)

Hartmann, Paul; Wenzl, Franz P.; Sommer, Christian; Pachler, Peter; Hoschopf, Hans; Schweighart, Marko; Hartmann, Martin; Kuna, Ladislav; Jakopic, Georg; Leising, Guenther; Tasch, Stefan

2006-08-01

At present, light-emitting diode (LED) modules in various shapes are developed and designed for the general lighting, advertisement, emergency lighting, design and architectural markets. To compete with and to surpass the performance of traditional lighting systems, enhancement of Lumen output and the white light quality as well as the thermal management and the luminary integration are key factors for success. Regarding these issues, white LEDs based on the chip-on-board (COB) technology show pronounced advantages. State-of-the-art LEDs exploiting this technology are now ready to enter the general lighting segments. We introduce and discuss the specific properties of the Tridonic COB technology dedicated for general lighting. This technology, in combination with a comprehensive set of tools to improve and to enhance the Lumen output and the white light quality, including optical simulation, is the scaffolding for the application of white LEDs in emerging areas, for which an outlook will be given.

Assessment of ultrasound modulation of near infrared light on the quantification of scattering coefficient.

PubMed

Singh, M Suheshkumar; Yalavarthy, Phaneendra K; Vasu, R M; Rajan, K

2010-07-01

To assess the effect of ultrasound modulation of near infrared (NIR) light on the quantification of scattering coefficient in tissue-mimicking biological phantoms. A unique method to estimate the phase of the modulated NIR light making use of only time averaged intensity measurements using a charge coupled device camera is used in this investigation. These experimental measurements from tissue-mimicking biological phantoms are used to estimate the differential pathlength, in turn leading to estimation of optical scattering coefficient. A Monte-Carlo model based numerical estimation of phase in lieu of ultrasound modulation is performed to verify the experimental results. The results indicate that the ultrasound modulation of NIR light enhances the effective scattering coefficient. The observed effective scattering coefficient enhancement in tissue-mimicking viscoelastic phantoms increases with increasing ultrasound drive voltage. The same trend is noticed as the ultrasound modulation frequency approaches the natural vibration frequency of the phantom material. The contrast enhancement is less for the stiffer (larger storage modulus) tissue, mimicking tumor necrotic core, compared to the normal tissue. The ultrasound modulation of the insonified region leads to an increase in the effective number of scattering events experienced by NIR light, increasing the measured phase, causing the enhancement in the effective scattering coefficient. The ultrasound modulation of NIR light could provide better estimation of scattering coefficient. The observed local enhancement of the effective scattering coefficient, in the ultrasound focal region, is validated using both experimental measurements and Monte-Carlo simulations.

Solvothermal synthesis of Bi2O3/BiVO4 heterojunction with enhanced visible-light photocatalytic performances

NASA Astrophysics Data System (ADS)

Ying, Wu; Jing, Wang; Yunfang, Huang; Yuelin, Wei; Zhixian, Sun; Xuanqing, Zheng; Chengkun, Zhang; Ningling, Zhou; Leqing, Fan; Jihuai, Wu

2016-08-01

Novel, three-dimensional, flower-like Bi2O3/BiVO4 heterojunction photocatalysts have been prepared by the combination of homogeneous precipitation and two-step solvothermal method followed by thermal solution of NaOH etching process. The as-obtained samples were fully characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, Brunauer-Emmett-Teller surface area, and UV—vis diffuse-reflectance spectroscopy in detail. The crystallinity, microstructure, specific surface area, optical property and photocatalytic activity of samples greatly changed depending on solvothermal reaction time. The photocatalytic activities of samples were evaluated on the degradation of methyl orange (MO) under visible-light irradiation. The Bi2O3/BiVO4 exhibited much higher photocatalytic activities than pure BiVO4 and conventional TiO2 (P25). The result revealed that the three-dimensional heterojunction played a critical role in the separation of the electron and hole pairs and enhancement of the interfacial charge transfer efficiency, which was responsible for the enhanced photocatalytic activity. Project supported by the National Natural Science Foundation of China (Nos. 61306077, 21301060), the Fundamental Research Funds for the Central Universities (Nos. JB-ZR1109, JB-ZR1212), the National Science Foundation of Quanzhou City (No. 2014Z108), the Promotion Program for Young and Middle-aged Teachers in Science and Technology Research of Huaqiao University (No. ZQN-PY207), Discipline Innovation Team Project of Huaqiao University (No. 201320), and the Instrumental Analysis Center Huaqiao University.

Upconverting device for enhanced recogntion of certain wavelengths of light

DOEpatents

Kross, Brian; McKIsson, John E; McKisson, John; Weisenberger, Andrew; Xi, Wenze; Zorn, Carl

2013-05-21

An upconverting device for enhanced recognition of selected wavelengths is provided. The device comprises a transparent light transmitter in combination with a plurality of upconverting nanoparticles. The device may a lens in eyewear or alternatively a transparent panel such as a window in an instrument or machine. In use the upconverting device is positioned between a light source and the eye(s) of the user of the upconverting device.

PHYTOCHROME KINASE SUBSTRATE1 Regulates Root Phototropism and Gravitropism1[C][W][OA

PubMed Central

Boccalandro, Hernán E.; De Simone, Silvia N.; Bergmann-Honsberger, Ariane; Schepens, Isabelle; Fankhauser, Christian; Casal, Jorge J.

2008-01-01

Light promotes the expression of PHYTOCHROME KINASE SUBSTRATE1 (PKS1) in the root of Arabidopsis thaliana, but the function of PKS1 in this organ is unknown. Unilateral blue light induced a negative root phototropic response mediated by phototropin 1 in wild-type seedlings. This response was absent in pks1 mutants. In the wild type, unilateral blue light enhanced PKS1 expression in the subapical region of the root several hours before bending was detectable. The negative phototropism and the enhanced PKS1 expression in response to blue light required phytochrome A (phyA). In addition, the pks1 mutation enhanced the root gravitropic response when vertically oriented seedlings were placed horizontally. The negative regulation of gravitropism by PKS1 occurred even in dark-grown seedlings and did not require phyA. Blue light also failed to induce negative phototropism in pks1 under reduced gravitational stimulation, indicating that the effect of pks1 on phototropism is not simply the consequence of the counteracting effect of enhanced gravitropism. We propose a model where the background level of PKS1 reduces gravitropism. After a phyA-dependent increase in its expression, PKS1 positively affects root phototropism and both effects contribute to negative curvature in response to unilateral blue light. PMID:18024556

PHYTOCHROME KINASE SUBSTRATE1 regulates root phototropism and gravitropism.

PubMed

Boccalandro, Hernán E; De Simone, Silvia N; Bergmann-Honsberger, Ariane; Schepens, Isabelle; Fankhauser, Christian; Casal, Jorge J

2008-01-01

Light promotes the expression of PHYTOCHROME KINASE SUBSTRATE1 (PKS1) in the root of Arabidopsis thaliana, but the function of PKS1 in this organ is unknown. Unilateral blue light induced a negative root phototropic response mediated by phototropin 1 in wild-type seedlings. This response was absent in pks1 mutants. In the wild type, unilateral blue light enhanced PKS1 expression in the subapical region of the root several hours before bending was detectable. The negative phototropism and the enhanced PKS1 expression in response to blue light required phytochrome A (phyA). In addition, the pks1 mutation enhanced the root gravitropic response when vertically oriented seedlings were placed horizontally. The negative regulation of gravitropism by PKS1 occurred even in dark-grown seedlings and did not require phyA. Blue light also failed to induce negative phototropism in pks1 under reduced gravitational stimulation, indicating that the effect of pks1 on phototropism is not simply the consequence of the counteracting effect of enhanced gravitropism. We propose a model where the background level of PKS1 reduces gravitropism. After a phyA-dependent increase in its expression, PKS1 positively affects root phototropism and both effects contribute to negative curvature in response to unilateral blue light.

Heat generation and light scattering of green fluorescent protein-like pigments in coral tissue

NASA Astrophysics Data System (ADS)

Lyndby, Niclas H.; Kühl, Michael; Wangpraseurt, Daniel

2016-05-01

Green fluorescent protein (GFP)-like pigments have been proposed to have beneficial effects on coral photobiology. Here, we investigated the relationships between green fluorescence, coral heating and tissue optics for the massive coral Dipsastraea sp. (previously Favia sp.). We used microsensors to measure tissue scalar irradiance and temperature along with hyperspectral imaging and combined imaging of variable chlorophyll fluorescence and green fluorescence. Green fluorescence correlated positively with coral heating and scalar irradiance enhancement at the tissue surface. Coral tissue heating saturated for maximal levels of green fluorescence. The action spectrum of coral surface heating revealed that heating was highest under red (peaking at 680 nm) irradiance. Scalar irradiance enhancement in coral tissue was highest when illuminated with blue light, but up to 62% (for the case of highest green fluorescence) of this photon enhancement was due to green fluorescence emission. We suggest that GFP-like pigments scatter the incident radiation, which enhances light absorption and heating of the coral. However, heating saturates, because intense light scattering reduces the vertical penetration depth through the tissue eventually leading to reduced light absorption at high fluorescent pigment density. We conclude that fluorescent pigments can have a central role in modulating coral light absorption and heating.

Photosensitivity enhancement with TiO2 in semitransparent light-sensitive skins of nanocrystal monolayers.

PubMed

Akhavan, Shahab; Yeltik, Aydan; Demir, Hilmi Volkan

2014-06-25

We propose and demonstrate light-sensitive nanocrystal skins that exhibit broadband sensitivity enhancement based on electron transfer to a thin TiO2 film grown by atomic layer deposition. In these photosensors, which operate with no external bias, photogenerated electrons remain trapped inside the nanocrystals. These electrons generally recombine with the photogenerated holes that accumulate at the top interfacing contact, which leads to lower photovoltage buildup. Because favorable conduction band offset aids in transferring photoelectrons from CdTe nanocrystals to the TiO2 layer, which decreases the exciton recombination probability, TiO2 has been utilized as the electron-accepting material in these light-sensitive nanocrystal skins. A controlled interface thickness between the TiO2 layer and the monolayer of CdTe nanocrystals enables a photovoltage buildup enhancement in the proposed nanostructure platform. With TiO2 serving as the electron acceptor, we observed broadband sensitivity improvement across 350-475 nm, with an approximately 22% enhancement. Furthermore, time-resolved fluorescence measurements verified the electron transfer from the CdTe nanocrystals to the TiO2 layer in light-sensitive skins. These results could pave the way for engineering nanocrystal-based light-sensing platforms, such as smart transparent windows, light-sensitive walls, and large-area optical detection systems.

Bridging the "green gap" of LEDs: giant light output enhancement and directional control of LEDs via embedded nano-void photonic crystals.

PubMed

Tsai, Yu-Lin; Liu, Che-Yu; Krishnan, Chirenjeevi; Lin, Da-Wei; Chu, You-Chen; Chen, Tzu-Pei; Shen, Tien-Lin; Kao, Tsung-Sheng; Charlton, Martin D B; Yu, Peichen; Lin, Chien-Chung; Kuo, Hao-Chung; He, Jr-Hau

2016-01-14

Green LEDs do not show the same level of performance as their blue and red cousins, greatly hindering the solid-state lighting development, which is the so-called "green gap". In this work, nano-void photonic crystals (NVPCs) were fabricated to embed within the GaN/InGaN green LEDs by using epitaxial lateral overgrowth (ELO) and nano-sphere lithography techniques. The NVPCs act as an efficient scattering back-reflector to outcouple the guided and downward photons, which not only boost the light extraction efficiency of LEDs with an enhancement of 78% but also collimate the view angle of LEDs from 131.5° to 114.0°. This could be because of the highly scattering nature of NVPCs which reduce the interference giving rise to Fabry-Perot resonance. Moreover, due to the threading dislocation suppression and strain relief by the NVPCs, the internal quantum efficiency was increased by 25% and droop behavior was reduced from 37.4% to 25.9%. The enhancement of light output power can be achieved as high as 151% at a driving current of 350 mA. Giant light output enhancement and directional control via NVPCs point the way towards a promising avenue of solid-state lighting.

Pole walking down-under: profile of pole walking leaders, walkers and programs in Australia and factors relating to participation.

PubMed

Fritschi, Juliette O; van Uffelen, Jannique G Z; Brown, Wendy J

2014-12-01

Although pole walking (PW) has the potential to be a useful health-enhancing physical activity (PA), little is known about by whom or how it is being practised. The aims of this study were to describe (1) the characteristics of PW leaders, pole walkers and PW programs in Australia, and (2) participants' perceptions of PW and their reasons for participation. In 2012, PW leaders (n=31) and walkers (n=107) completed self-administered surveys that included questions about participants' sociodemographic and health characteristics, PW programs and perceptions of PW. Data were analysed using SPSS. Leaders and walkers were generally born in Australia (leaders, 71%; walkers, 83%), older (leaders, 55 years [s.d. 11.5]; walkers, 65 years [s.d. 10.6]) and female (leaders, 77%; walkers, 79%). Most walkers (82%) walked regularly in groups, approximately once per week for about an hour, at light to moderate intensity. The program's aims most strongly endorsed by PW leaders were to increase participant enjoyment (90%), increase PA levels (81%), provide a positive social experience (77%) and increase PA confidence (71%). The most strongly endorsed motivations for PW among walkers were to remain physically active (63%), improve fitness (62%) and personal and social enjoyment (60%). In Australia, PW is being practised by a health conscious, older population. It is perceived as an enjoyable and health-enhancing outdoor activity. SO WHAT?: Health and exercise practitioners may find that PW is a beneficial form of PA for older Australians.

Acute exposure to blue wavelength light during memory consolidation improves verbal memory performance.

PubMed

Alkozei, Anna; Smith, Ryan; Dailey, Natalie S; Bajaj, Sahil; Killgore, William D S

2017-01-01

Acute exposure to light within the blue wavelengths has been shown to enhance alertness and vigilance, and lead to improved speed on reaction time tasks, possibly due to activation of the noradrenergic system. It remains unclear, however, whether the effects of blue light extend beyond simple alertness processes to also enhance other aspects of cognition, such as memory performance. The aim of this study was to investigate the effects of a thirty minute pulse of blue light versus placebo (amber light) exposure in healthy normally rested individuals in the morning during verbal memory consolidation (i.e., 1.5 hours after memory acquisition) using an abbreviated version of the California Verbal Learning Test (CVLT-II). At delayed recall, individuals who received blue light (n = 12) during the consolidation period showed significantly better long-delay verbal recall than individuals who received amber light exposure (n = 18), while controlling for the effects of general intelligence, depressive symptoms and habitual wake time. These findings extend previous work demonstrating the effect of blue light on brain activation and alertness to further demonstrate its effectiveness at facilitating better memory consolidation and subsequent retention of verbal material. Although preliminary, these findings point to a potential application of blue wavelength light to optimize memory performance in healthy populations. It remains to be determined whether blue light exposure may also enhance performance in clinical populations with memory deficits.

Multiple phytochromes are involved in red-light-induced enhancement of first-positive phototropism in arabidopsis thaliana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janoudi, A.K.; Gordon, W.R.; Poff, K.L.

1997-03-01

The amplitude of phototropic curvature to blue light is enhanced by a prior exposure of seedlings to red light. This enhancement is mediated by phytochrome. Fluence-response relationships have been constructed for red-light-induced enhancement in the phytochrome A (phyA) null mutant, the phytochrome B- (phyB) deficient mutant, and in two transgenic lines of Arabidopsis thaliana that overexpress either phyA or phyB. These fluence-response relationships demonstrate the existence of two responses in enhancement, a response in the very-low-to-low-fluence range, and a response in the high-fluence range. Only the response in the high-fluence range is present in the phyA null mutant. In contrast,more » the phyB-deficient mutant is indistinguishable from the wild-type parent in red-light responsiveness. These data indicate that phyA is necessary for the very-low-to-low but not the high-fluence response, and that phyB is not necessary for either response range. Based on these results, the high-fluence response, if controlled by a single phytochrome, must be controlled by a phytochrome other than phyA or phyB. Overexpression of phyA has a negative effect and overexpression of phyB has an enhancing effect in the high fluence range. These results suggest that overexpression of either phytochrome perturbs the function of the endogenous photoreceptor system in unpreditable fashion. 25 refs., 3 figs.« less

Light-Drag Enhancement by a Highly Dispersive Rubidium Vapor.

PubMed

Safari, Akbar; De Leon, Israel; Mirhosseini, Mohammad; Magaña-Loaiza, Omar S; Boyd, Robert W

2016-01-08

The change in the speed of light as it propagates through a moving material has been a subject of study for almost two centuries. This phenomenon, known as the Fresnel light-drag effect, is quite small and usually requires a large interaction path length and/or a large velocity of the moving medium to be observed. Here, we show experimentally that the observed drag effect can be enhanced by over 2 orders of magnitude when the light beam propagates through a moving slow-light medium. Our results are in good agreement with the theoretical prediction, which indicates that, in the limit of large group indices, the strength of the light-drag effect is proportional to the group index of the moving medium.

Exposure to light enhances pre-adult fitness in two dark-dwelling sympatric species of ants

PubMed Central

Lone, Shahnaz Rahman; Sharma, Vijay Kumar

2008-01-01

Background In insects, circadian clocks play a key role in enhancing fitness by regulating life history traits such as developmental time and adult lifespan. These clocks use environmental light/dark (LD) cycles to fine-tune a wide range of behavioral and physiological processes. To study the effect of environmental LD conditions on pre-adult fitness components, we used two dark-dwelling sympatric species of ants (the night active Camponotus compressus and the day active Camponotus paria), which normally develop underground and have fairly long pre-adult developmental time. Results Our results suggest that ants develop fastest as pre-adults when maintained under constant light (LL), followed closely by 12:12 hr light/dark (LD), and then constant darkness (DD). While light exposure alters developmental rates of almost all stages of development, the overall pre-adult development in LL is speeded-up (relative to DD) by ~37% (34 days) in C. compressus and by ~35% (31 days) in C. paria. In LD too, development is faster (relative to DD) by ~29% (26 days) in C. compressus and by ~28% (25 days) in C. paria. Pre-adult viability of both species is also higher under LL and LD compared to DD. While pre-adult development time and viability is enhanced in LL and LD, clutch-size undergoes reduction, at least in C. compressus. Conclusion Exposure to light enhances pre-adult fitness in two dark-dwelling species of Camponotus by speeding-up development and by enhancing viability. This suggests that social ants use environmental light/dark cycles to modulate key life history traits such as pre-adult development time and viability. PMID:19046462

Effect of light-enhanced bleaching on in vitro surface and intrapulpal temperature rise.

PubMed

Baik, J W; Rueggeberg, F A; Liewehr, F R

2001-01-01

This study investigated the effect of the presence, absence, and aging of a heat-enhancing compound (colorant) added to bleaching gel on the temperature rise of the gel itself, as well as the temperature rise within the pulp chamber, when a tooth was exposed to a variety of light-curing units in vitro. An extracted human upper central incisor was fitted with thermocouples placed in the pulp chamber as well as on the facial tooth surface. A temperature-controlled simulated intrapulpal fluid flow was provided to the tooth, and bleaching agent (Opalesence XTRA, Ultradent) containing heat-enhancing colorant, aged colorant, or no colorant was applied to the facial surface. The tooth and light-curing unit were placed in a thermostatically controlled oven at 37 degrees C, and real-time gel and intrapulpal temperature values were recorded digitally. Light-curing units used were a plasma arc light (PAC) (PowerPac, ADT), a conventional quartz tungsten halogen source (QTH) (Optilux 501, Demetron/Kerr), the QTH light used in high-power (bleaching) mode, and an argon ion laser (AccuCure 3000, LaserMed). An exposure scenario simulating light-enhanced bleaching of 10 upper teeth was developed. Temperature rise over the pre-exposure, baseline value associated with the last light exposure in the bleaching sequence was calculated for each curing and bleaching combination. Five replications for each test condition were made. Temperature rise values were compared using analysis of variance (ANOVA) at a preset alpha of 0.05. When fresh colorant-containing bleach was used, the PAC light increased bleach temperature 39.3 degrees C above baseline. With no added colorant, temperature rise was 37.1 degrees C. The QTH light in bleach mode resulted in gel temperature 24.8 degrees C above baseline, whereas the temperature increase was only 11.5 degrees C when no colorant was used. Conventional QTH light use increased fresh bleach temperature by 17.7 degrees C, whereas an increase of only 11.1 degrees C was measured without colorant. The argon ion laser produced equivalent temperature rise regardless of the presence or freshness of the colorant, approximately 9.4 degrees C. Intrapulpal temperatures were all significantly lower than those recorded in the bleaching gel and ranged from 5 degrees to 8 degrees C. As a rule, the presence of fresh heat-enhancing colorant in the bleaching gel resulted in a significant intrapulpal temperature increase (approximately 1 degrees C) over that reached using other lights. The PAC and the QTH light used in bleach mode induced greater intrapulpal temperature rise than the laser. Freshness of bleaching agent incorporating light-activated, heat-enhancing colorant influences temperature rise of bleaching gel and also may increase intrapulpal temperature values. Use of intense lights does elevate bleach temperature and also results in increased intrapulpal temperature that may further impact on patient sensitivity and pulpal health resulting from this treatment.

The Impact of parasitic loss on solar cells with plasmonic nano-textured rear reflectors.

PubMed

Disney, Claire E R; Pillai, Supriya; Green, Martin A

2017-10-09

Significant photocurrent enhancement has been demonstrated using plasmonic light-trapping structures comprising nanostructured metallic features at the rear of the cell. These structures have conversely been identified as suffering heightened parasitic absorption into the metal at certain resonant wavelengths severely mitigating benefits of light trapping. In this study, we undertook simulations exploring the relationship between enhanced absorption into the solar cell, and parasitic losses in the metal. These simulations reveal that resonant wavelengths associated with high parasitic losses in the metal could also be associated with high absorption enhancement in the solar cell. We identify mechanisms linking these parasitic losses and absorption enhancements, but found that by ensuring correct design, the light trapping structures will have a positive impact on the overall solar cell performance. Our results clearly show that the large angle scattering provided by the plasmonic nanostructures is the reason for the enhanced absorption observed in the solar cells.

MoS2 monolayers on nanocavities: enhancement in light-matter interaction

NASA Astrophysics Data System (ADS)

Janisch, Corey; Song, Haomin; Zhou, Chanjing; Lin, Zhong; Elías, Ana Laura; Ji, Dengxin; Terrones, Mauricio; Gan, Qiaoqiang; Liu, Zhiwen

2016-06-01

Two-dimensional (2D) atomic crystals and van der Waals heterostructures constitute an emerging platform for developing new functional ultra-thin electronic and optoelectronic materials for novel energy-efficient devices. However, in most thin-film optical applications, there is a long-existing trade-off between the effectiveness of light-matter interactions and the thickness of semiconductor materials, especially when the materials are scaled down to atom thick dimensions. Consequently, enhancement strategies can introduce significant advances to these atomically thick materials and devices. Here we demonstrate enhanced absorption and photoluminescence generation from MoS2 monolayers coupled with a planar nanocavity. This nanocavity consists of an alumina nanolayer spacer sandwiched between monolayer MoS2 and an aluminum reflector, and can strongly enhance the light-matter interaction within the MoS2, increasing the exclusive absorption of monolayer MoS2 to nearly 70% at a wavelength of 450 nm. The nanocavity also modifies the spontaneous emission rate, providing an additional design freedom to control the interaction between light and 2D materials.

Enhanced optical output power of blue light-emitting diodes with quasi-aligned gold nanoparticles

PubMed Central

2014-01-01

The output power of the light from GaN-based light-emitting diodes (LEDs) was enhanced by fabricating gold (Au) nanoparticles on the surface of p-GaN. Quasi-aligned Au nanoparticle arrays were prepared by depositing Au thin film on an aligned suspended carbon nanotube thin film surface and then putting the Au-CNT system on the surface of p-GaN and thermally annealing the sample. The size and position of the Au nanoparticles were confined by the carbon nanotube framework, and no other additional residual Au was distributed on the surface of the p-GaN substrate. The output power of the light from the LEDs with Au nanoparticles was enhanced by 55.3% for an injected current of 100 mA with the electrical property unchanged compared with the conventional planar LEDs. The enhancement may originate from the surface plasmon effect and scattering effect of the Au nanoparticles. PMID:24393473

Enhanced light element imaging in atomic resolution scanning transmission electron microscopy.

PubMed

Findlay, S D; Kohno, Y; Cardamone, L A; Ikuhara, Y; Shibata, N

2014-01-01

We show that an imaging mode based on taking the difference between signals recorded from the bright field (forward scattering region) in atomic resolution scanning transmission electron microscopy provides an enhancement of the detectability of light elements over existing techniques. In some instances this is an enhancement of the visibility of the light element columns relative to heavy element columns. In all cases explored it is an enhancement in the signal-to-noise ratio of the image at the light column site. The image formation mechanisms are explained and the technique is compared with earlier approaches. Experimental data, supported by simulation, are presented for imaging the oxygen columns in LaAlO₃. Case studies looking at imaging hydrogen columns in YH₂ and lithium columns in Al₃Li are also explored through simulation, particularly with respect to the dependence on defocus, probe-forming aperture angle and detector collection aperture angles. © 2013 Elsevier B.V. All rights reserved.

Substrate-induced interfacial plasmonics for photovoltaic conversion

PubMed Central

Li, Xinxi; Jia, Chuancheng; Ma, Bangjun; Wang, Wei; Fang, Zheyu; Zhang, Guoqing; Guo, Xuefeng

2015-01-01

Surface plasmon resonance (SPR) is widely used as light trapping schemes in solar cells, because it can concentrate light fields surrounding metal nanostructures and realize light management at the nanoscale. SPR in photovoltaics generally occurs at the metal/dielectric interfaces. A well-defined interface is therefore required to elucidate interfacial SPR processes. Here, we designed a photovoltaic device (PVD) with an atomically flat TiO2 dielectric/dye/graphene/metal nanoparticle (NP) interface for quantitatively studying the SPR enhancement of the photovoltaic conversion. Theoretical and experimental results indicated that the graphene monolayer was transparent to the electromagnetic field. This transparency led to significant substrate-induced plasmonic hybridization at the heterostructure interface. Combined with interparticle plasmonic coupling, the substrate-induced plasmonics concentrated light at the interface and enhanced the photo-excitation of dyes, thus improving the photoelectric conversion. Such a mechanistic understanding of interfacial plasmonic enhancement will further promote the development of efficient plasmon-enhanced solar cells and composite photocatalysts. PMID:26412576

Enhanced light absorption by mixed source black and brown carbon particles in UK winter

PubMed Central

Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; Dubey, Manvendra K.; Cappa, Christopher D.; Williams, Leah R.; Herndon, Scott C.; Massoli, Paola; Fortner, Edward C.; Chhabra, Puneet S.; Brooks, William A.; Onasch, Timothy B.; Jayne, John T.; Worsnop, Douglas R.; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L.; Liu, Dantong; Allan, James D.; Lee, James D.; Fleming, Zoë L.; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S. H.

2015-01-01

Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models. PMID:26419204

Enhanced light absorption by mixed source black and brown carbon particles in UK winter

DOE PAGES

Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; ...

2015-09-30

We report that black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC’s light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ~1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC’s warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combinationmore » of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. In conclusion, we find that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.« less

Photo-reactive charge trapping memory based on lanthanide complex.

PubMed

Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V A L

2015-10-09

Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 10(4) s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices.

Photo-reactive charge trapping memory based on lanthanide complex

NASA Astrophysics Data System (ADS)

Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V. A. L.

2015-10-01

Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 104 s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices.

Slow light enhanced optical nonlinearity in a silicon photonic crystal coupled-resonator optical waveguide.

PubMed

Matsuda, Nobuyuki; Kato, Takumi; Harada, Ken-Ichi; Takesue, Hiroki; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya

2011-10-10

We demonstrate highly enhanced optical nonlinearity in a coupled-resonator optical waveguide (CROW) in a four-wave mixing experiment. Using a CROW consisting of 200 coupled resonators based on width-modulated photonic crystal nanocavities in a line defect, we obtained an effective nonlinear constant exceeding 10,000 /W/m, thanks to slow light propagation combined with a strong spatial confinement of light achieved by the wavelength-sized cavities.

Optical devices featuring nonpolar textured semiconductor layers

DOEpatents

Moustakas, Theodore D; Moldawer, Adam; Bhattacharyya, Anirban; Abell, Joshua

2013-11-26

A semiconductor emitter, or precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate in a nonpolar orientation. The textured layers enhance light extraction, and the use of nonpolar orientation greatly enhances internal quantum efficiency compared to conventional devices. Both the internal and external quantum efficiencies of emitters of the invention can be 70-80% or higher. The invention provides highly efficient light emitting diodes suitable for solid state lighting.

Zeaxanthin Binds to Light-Harvesting Complex Stress-Related Protein to Enhance Nonphotochemical Quenching in Physcomitrella patens[W

PubMed Central

Pinnola, Alberta; Dall’Osto, Luca; Gerotto, Caterina; Morosinotto, Tomas; Bassi, Roberto; Alboresi, Alessandro

2013-01-01

Nonphotochemical quenching (NPQ) dissipates excess energy to protect the photosynthetic apparatus from excess light. The moss Physcomitrella patens exhibits strong NPQ by both algal-type light-harvesting complex stress-related (LHCSR)–dependent and plant-type S subunit of Photosystem II (PSBS)-dependent mechanisms. In this work, we studied the dependence of NPQ reactions on zeaxanthin, which is synthesized under light stress by violaxanthin deepoxidase (VDE) from preexisting violaxanthin. We produced vde knockout (KO) plants and showed they underwent a dramatic reduction in thermal dissipation ability and enhanced photoinhibition in excess light conditions. Multiple mutants (vde lhcsr KO and vde psbs KO) showed that zeaxanthin had a major influence on LHCSR-dependent NPQ, in contrast with previous reports in Chlamydomonas reinhardtii. The PSBS-dependent component of quenching was less dependent on zeaxanthin, despite the near-complete violaxanthin to zeaxanthin exchange in LHC proteins. Consistent with this, we provide biochemical evidence that native LHCSR protein binds zeaxanthin upon excess light stress. These findings suggest that zeaxanthin played an important role in the adaptation of modern plants to the enhanced levels of oxygen and excess light intensity of land environments. PMID:24014548

Zeaxanthin binds to light-harvesting complex stress-related protein to enhance nonphotochemical quenching in Physcomitrella patens.

PubMed

Pinnola, Alberta; Dall'Osto, Luca; Gerotto, Caterina; Morosinotto, Tomas; Bassi, Roberto; Alboresi, Alessandro

2013-09-01

Nonphotochemical quenching (NPQ) dissipates excess energy to protect the photosynthetic apparatus from excess light. The moss Physcomitrella patens exhibits strong NPQ by both algal-type light-harvesting complex stress-related (LHCSR)-dependent and plant-type S subunit of Photosystem II (PSBS)-dependent mechanisms. In this work, we studied the dependence of NPQ reactions on zeaxanthin, which is synthesized under light stress by violaxanthin deepoxidase (VDE) from preexisting violaxanthin. We produced vde knockout (KO) plants and showed they underwent a dramatic reduction in thermal dissipation ability and enhanced photoinhibition in excess light conditions. Multiple mutants (vde lhcsr KO and vde psbs KO) showed that zeaxanthin had a major influence on LHCSR-dependent NPQ, in contrast with previous reports in Chlamydomonas reinhardtii. The PSBS-dependent component of quenching was less dependent on zeaxanthin, despite the near-complete violaxanthin to zeaxanthin exchange in LHC proteins. Consistent with this, we provide biochemical evidence that native LHCSR protein binds zeaxanthin upon excess light stress. These findings suggest that zeaxanthin played an important role in the adaptation of modern plants to the enhanced levels of oxygen and excess light intensity of land environments.

Laser remote sensing of backscattered light from a target sample

DOEpatents

Sweatt, William C [Albuquerque, NM; Williams, John D [Albuquerque, NM

2008-02-26

A laser remote sensing apparatus comprises a laser to provide collimated excitation light at a wavelength; a sensing optic, comprising at least one optical element having a front receiving surface to focus the received excitation light onto a back surface comprising a target sample and wherein the target sample emits a return light signal that is recollimated by the front receiving surface; a telescope for collecting the recollimated return light signal from the sensing optic; and a detector for detecting and spectrally resolving the return light signal. The back surface further can comprise a substrate that absorbs the target sample from an environment. For example the substrate can be a SERS substrate comprising a roughened metal surface. The return light signal can be a surface-enhanced Raman signal or laser-induced fluorescence signal. For fluorescence applications, the return signal can be enhanced by about 10.sup.5, solely due to recollimation of the fluorescence return signal. For SERS applications, the return signal can be enhanced by 10.sup.9 or more, due both to recollimation and to structuring of the SERS substrate so that the incident laser and Raman scattered fields are in resonance with the surface plasmons of the SERS substrate.

Ultrasonic signal enhancement by resonator techniques

NASA Technical Reports Server (NTRS)

Heyman, J. S.

1973-01-01

Ultrasonic resonators increase experimental sensitivity to acoustic dispersion and changes in attenuation. Experimental sensitivity enhancement line shapes are presented which were obtained by modulating the acoustic properties of a CdS resonator with a light beam. Small changes in light level are made to produce almost pure absorptive or dispersive changes in the resonator signal. This effect is due to the coupling of the ultrasonic wave to the CdS conductivity which is proportional to incident light intensity. The resonator conductivity is adjusted in this manner to obtain both dispersive and absorptive sensitivity enhancement line shapes. The data presented verify previous thoretical calculations based on a propagating wave model.

Curriculum Redesign in Veterinary Medicine: Part II.

PubMed

Macik, Maria L; Chaney, Kristin P; Turner, Jacqueline S; Rogers, Kenita S; Scallan, Elizabeth M; Korich, Jodi A; Fowler, Debra; Keefe, Lisa M

Curricular review is considered a necessary component for growth and enhancement of academic programs and requires time, energy, creativity, and persistence from both faculty and administration. On a larger scale, a comprehensive redesign effort involves forming a dedicated faculty redesign team, developing program learning outcomes, mapping the existing curriculum, and reviewing the curriculum in light of collected stakeholder data. The faculty of the Texas A&M University College of Veterinary Medicine & Biomedical Sciences (TAMU) recently embarked on a comprehensive curriculum redesign effort through partnership with the university's Center for Teaching Excellence. Using a previously developed evidence-based model of program redesign, TAMU created a process for use in veterinary medical education, which is described in detail in the first part of this article series. An additional component of the redesign process that is understated, yet vital for success, is faculty buy-in and support. Without faculty engagement, implementation of data-driven curricular changes stemming from program evaluation may be challenging. This second part of the article series describes the methodology for encouraging faculty engagement through the final steps of the redesign initiative and the lessons learned by TAMU through the redesign process.

Single-Cell RNA-Seq Reveals Dynamic Early Embryonic-like Programs during Chemical Reprogramming.

PubMed

Zhao, Ting; Fu, Yao; Zhu, Jialiang; Liu, Yifang; Zhang, Qian; Yi, Zexuan; Chen, Shi; Jiao, Zhonggang; Xu, Xiaochan; Xu, Junquan; Duo, Shuguang; Bai, Yun; Tang, Chao; Li, Cheng; Deng, Hongkui

2018-06-12

Chemical reprogramming provides a powerful platform for exploring the molecular dynamics that lead to pluripotency. Although previous studies have uncovered an intermediate extraembryonic endoderm (XEN)-like state during this process, the molecular underpinnings of pluripotency acquisition remain largely undefined. Here, we profile 36,199 single-cell transcriptomes at multiple time points throughout a highly efficient chemical reprogramming system using RNA-sequencing and reconstruct their progression trajectories. Through identifying sequential molecular events, we reveal that the dynamic early embryonic-like programs are key aspects of successful reprogramming from XEN-like state to pluripotency, including the concomitant transcriptomic signatures of two-cell (2C) embryonic-like and early pluripotency programs and the epigenetic signature of notable genome-wide DNA demethylation. Moreover, via enhancing the 2C-like program by fine-tuning chemical treatment, the reprogramming process is remarkably accelerated. Collectively, our findings offer a high-resolution dissection of cell fate dynamics during chemical reprogramming and shed light on mechanistic insights into the nature of induced pluripotency. Copyright © 2018 Elsevier Inc. All rights reserved.

Light-triggered liposomal cargo delivery platform incorporating photosensitizers and gold nanoparticles for enhanced singlet oxygen generation and increased cytotoxicity

NASA Astrophysics Data System (ADS)

Kautzka, Zofia; Clement, Sandhya; Goldys, Ewa M.; Deng, Wei

2018-02-01

We developed light-triggered liposomes incorporating gold nanoparticles and Rose Bengal (RB), a well-known photosensitizer used for photodynamic therapy. Singlet oxygen generated by these liposomes with 532 nm light illumination was characterized by adjusting the molar ratio of lipids and gold nanoparticles while keeping the amount of RB constant. Gold nanoparticles were found to enhance the singlet oxygen generation rate, with a maximum enhancement factor of 1.75 obtained for the molar ratio of HSPC: PE-NH2: gold of 57:5:17 compared with liposomes loaded with RB alone. The experimental results could be explained by the local electric field enhancement caused by gold nanoparticles. We further assessed cellular cytotoxicity of these liposomes by encapsulating an antitumor drug, doxorubicin (Dox); such Dox loaded liposomes were applied to human colorectal cancer cells, HCT116, and exposed to light. Gold-loaded liposomes containing RB and Dox where Dox release was triggered by light were found to exhibit higher cytotoxicity, compared to the liposomes loaded with RB and Dox alone. Our results indicate that gold-loaded liposomes incorporating photosensitizers may have improved therapeutic efficacy in photodynamic therapy and chemotherapy.

Broadband and omnidirectional light harvesting enhancement in photovoltaic devices with aperiodic TiO2 nanotube photonic crystal

NASA Astrophysics Data System (ADS)

Guo, Min; Su, Haijun; Zhang, Jun; Liu, Lin; Fu, Nianqing; Yong, Zehui; Huang, Haitao; Xie, Keyu

2017-03-01

Design of more effective broadband light-trapping elements to improve the light harvesting efficiency under both normal and tilted light for solar cells and other photonic devices is highly desirable. Herein we present a theoretical analysis on the optical properties of a novel TiO2 nanotube aperiodic photonic crystal (NT APC) following an aperiodic sequences and its photocurrent enhancement effect for dye-sensitized solar cells (DSSCs) under various incidence angles. It is found that, compared to regular PC, the designed TiO2 NT APC owns broader reflection region and a desired omnidirectional reflection (ODR) bandgaps, leading to considerable and stable photocurrent enhancement under both normal and oblique light. The effects of the structural parameters of the TiO2 NT APC, including the average lattice constant and the common sequence difference, on the optical properties, ODR bandgaps and absorption magnification of the integrated DSSCs are investigated in detail. Moreover, the angular dependence of photocurrent enhancement and angular compensation effect of such TiO2 NT APCs are also provided to offer a guidance on the optimum structural parameters design under different engineering application conditions.

Simultaneous enhancement of photo- and electroluminescence in white organic light-emitting devices by localized surface plasmons of silver nanoclusters

NASA Astrophysics Data System (ADS)

Yu, Jingting; Zhu, Wenqing; Shi, Guanjie; Zhai, Guangsheng; Qian, Bingjie; Li, Jun

2017-02-01

White organic light-emitting devices (WOLEDs) with enhanced current efficiency and negligible color shifting equipped with an internal color conversion layer (CCL) were fabricated. They were attained by embedding a single layer of silver nanoclusters (SNCs) between the CCL and light-emitting layer (EML). The simultaneous enhancement of the photoluminescence (PL) of the CCL and electroluminescence (EL) of the EML were realized by controlling the thickness and size of the SNCs to match the localized surface plasmon resonance spectrum with the PL spectrum of the CCL and the EL spectrum of the EML. The WOLED with optimal SNCs demonstrated a 25.81% enhancement in current efficiency at 60 mA cm-2 and good color stability over the entire range of current density.

Hexagonal Ag nanoarrays induced enhancement of blue light emission from amorphous oxidized silicon nitride via localized surface plasmon coupling.

PubMed

Ma, Zhongyuan; Ni, Xiaodong; Zhang, Wenping; Jiang, Xiaofan; Yang, Huafeng; Yu, Jie; Wang, Wen; Xu, Ling; Xu, Jun; Chen, Kunji; Feng, Duan

2014-11-17

A significant enhancement of blue light emission from amorphous oxidized silicon nitride (a-SiNx:O) films is achieved by introduction of ordered and size-controllable arrays of Ag nanoparticles between the silicon substrate and a-SiNx:O films. Using hexagonal arrays of Ag nanoparticles fabricated by nanosphere lithography, the localized surface plasmons (LSPs) resonance can effectively increase the internal quantum efficiency from 3.9% to 13.3%. Theoretical calculation confirms that the electromagnetic field-intensity enhancement is through the dipole surface plasma coupling with the excitons of a-SiNx:O films, which demonstrates a-SiNx:O films with enhanced blue emission are promising for silicon-based light-emitting applications by patterned Ag arrays.

Short-Wavelength Light-Emitting Devices With Enhanced Hole Injection Currents

DTIC Science & Technology

2005-05-01

hot-hole injector with appreciably enhancement of the injection current is proposed and developed to be integrated with commonly used vertical...structures of the emitting devices. Second, we develop the alternative design of UV-light sources on the base of lateral p+ - i - n+ superlattice structures...enhancement of the injection current is proposed and developed to be integrated with commonly used vertical structures of the emitting devices. Second

Dose evaluation of an NIPAM polymer gel dosimeter using gamma index

NASA Astrophysics Data System (ADS)

Chang, Yuan-Jen; Lin, Jing-Quan; Hsieh, Bor-Tsung; Yao, Chun-Hsu; Chen, Chin-Hsing

2014-11-01

An N-isopropylacrylamide (NIPAM) polymer gel dosimeter has great potential in clinical applications. However, its three-dimensional dose distribution must be assessed. In this work, a quantitative evaluation of dose distributions was performed to evaluate the NIPAM polymer gel dosimeter using gamma analysis. A cylindrical acrylic phantom filled with NIPAM gel measuring 10 cm (diameter) by 10 cm (height) by 3 mm (thickness) was irradiated by a 4×4 cm2 square light field. The irradiated gel phantom was scanned using an optical computed tomography (optical CT) scanner (OCTOPUS™, MGS Research, Inc., Madison, CT, USA) at 1 mm resolution. The projection data were transferred to an image reconstruction program, which was written using MATLAB (The MathWorks, Natick, MA, USA). The program reconstructed the image of the optical density distribution using the algorithm of a filter back-projection. Three batches of replicated gel phantoms were independently measured. The average uncertainty of the measurements was less than 1%. The gel was found to have a high degree of spatial uniformity throughout the dosimeter and good temporal stability. A comparison of the line profiles of the treatment planning system and of the data measured by optical CT showed that the dose was overestimated in the penumbra region because of two factors. The first is light scattering due to changes in the refractive index at the edge of the irradiated field. The second is the edge enhancement caused by free radical diffusion. However, the effect of edge enhancement on the NIPAM gel dosimeter is not as significant as that on the BANG gel dosimeter. Moreover, the dose uncertainty is affected by the inaccuracy of the gel container positioning process. To reduce the uncertainty of 3D dose distribution, improvements in the gel container holder must be developed.

Polychromatic Supplemental Lighting from underneath Canopy Is More Effective to Enhance Tomato Plant Development by Improving Leaf Photosynthesis and Stomatal Regulation

PubMed Central

Song, Yu; Jiang, Chengyao; Gao, Lihong

2016-01-01

Light insufficient stress caused by canopy interception and mutual shading is a major factor limiting plant growth and development in intensive crop cultivation. Supplemental lighting can be used to give light to the lower canopy leaves and is considered to be an effective method to cope with low irradiation stress. Leaf photosynthesis, stomatal regulation, and plant growth and development of young tomato plants were examined to estimate the effects of supplemental lighting with various composite spectra and different light orientations. Light-emitting diodes (LEDs) of polychromatic light quality, red + blue (R/B), white + red + blue (W/R/B), white + red + far-red (W/R/FR), and white + blue (W/B) were assembled from the underneath canopy or from the inner canopy as supplemental lighting resources. The results showed that the use of supplemental lighting significantly increased the photosynthetic efficiency, and reduced stomatal closure while promoting plant growth. Among all supplemental lighting treatments, the W/R/B and W/B from the underneath canopy had best performance. The different photosynthetic performances among the supplemental lighting treatments are resulted from variations in CO2 utilization. The enhanced blue light fraction in the W/R/B and W/B could better stimulate stomatal opening and promote photosynthetic electron transport activity, thus better improving photosynthetic rate. Compared with the inner canopy treatment, the supplemental lighting from the underneath canopy could better enhance the carbon dioxide assimilation efficiency and excessive energy dissipation, leading to an improved photosynthetic performance. Stomatal morphology was highly correlated to leaf photosynthesis and plant development, and should thus be an important determinant for the photosynthesis and the growth of greenhouse tomatoes. PMID:28018376

Improving the optical performance of InGaN light-emitting diodes by altering light reflection and refraction with triangular air prism arrays.

PubMed

Kang, Ji Hye; Kim, Hyung Gu; Chandramohan, S; Kim, Hyun Kyu; Kim, Hee Yun; Ryu, Jae Hyoung; Park, Young Jae; Beak, Yun Seon; Lee, Jeong-Sik; Park, Joong Seo; Lysak, Volodymyr V; Hong, Chang-Hee

2012-01-01

The effect of triangular air prism (TAP) arrays with different distance-to-width (d/w) ratios on the enhancement of light extraction efficiency (LEE) of InGaN light-emitting diodes (LEDs) is investigated. The TAP arrays embedded at the sapphire/GaN interface act as light reflectors and refractors, and thereby improve the light output power due to the redirection of light into escape cones on both the front and back sides of the LED. Enhancement in radiometric power as high as 117% and far-field angle as low as 129° are realized with a compact arrangement of TAP arrays compared with that of a conventional LED made without TAP arrays under an injection current of 20 mA. © 2012 Optical Society of America

Simulation for light extraction efficiency of OLEDs with spheroidal microlenses in hexagonal array

NASA Astrophysics Data System (ADS)

Bae, Hyungchul; Kim, Jun Soo; Hong, Chinsoo

2018-05-01

A theoretical model based on ray optics is used to simulate the optical performance of organic light-emitting diodes (OLEDs) with spheroidal microlens arrays (MLAs) in a hexagonal array configuration using the Monte Carlo method. In simulations, ray tracing was performed until 20 reflections occurred from the metal cathode, with 10 consecutive reflections permitted in a single lens pattern. The parameters describing the shape and array of the lens pattern of a MLA are its radius, height, contact angle, and fill factor (FF). Many previous results on how these parameters affect light extraction efficiency (LEE) are inconsistent. In this paper, these contradictory results are discussed and explained by introducing a new parameter. To examine light extraction from an OLED through a MLA, the LEE enhancement is studied considering the effect of absorption by indium tin oxide during multiple reflections from the metal cathode. The device size where LEE enhancement is unchanged with changing lens pattern was identified for a fixed FF; under this condition, the optimal LEE enhancement, 84%, can be obtained using an OLED with a close-packed spheroidal MLA. An ideal maximum LEE enhancement of 120% was achieved with a device with an infinite-sized MLA. The angular intensity distribution of light emitted through a MLA is considered in addition to LEE enhancement for an optimized MLA.

Enhanced light absorptivity of black carbon with air pollution development in urban Beijing, China

NASA Astrophysics Data System (ADS)

Zhang, Y.; Zhang, Q.; Cheng, Y.; Su, H.; He, K.

2017-12-01

The impacts of black carbon (BC) aerosols on air quality and climate are dependent on BC light absorptivity. However, the light absorptivity of ambient BC-containing particles remains conflicting. In this work, we investigated the evolution of BC light absorptivity with pollution development in urban Beijing, China. We found that the mass absorption cross-section (MAC) of ambient BC-containing particles measured during the campaign increased with BC mass concentration, which can be attributed to more coating materials on BC surface with pollution development. A single-particle soot photometer (SP2) measurement showed that the coating thickness (CT) of BC-containing particles increased by 48% with PM1 and BC mass concentration increasing from 10 μg m-3 and 0.3 μg m-3 to 230 μg m-3 and 12 μg m-3. Based on Mie calculation, the CT increase could led to light absorption enhancement (Eab) of BC-containing particles increasing by 22%, consistent with the increase of measured MAC. The relationship between growth rate of BC light absorptivity (kEab) and that of PM1 or rBC concentration (kPM1 or krBC) showed that kEab ≈ 4.8% kPM1 or kEab ≈ 2.5% krBC. The analysis of effective emission intensity (EEI) for BC revealed that the enhancement of BC light absorptivity with increasing pollution levels was dominated by regional transport. During the pollution period, 63% of BC over Beijing originated from regional sources. The aging of these regional BC during atmospheric transport controlled the increase of coating materials for BC-containing particles observed in Beijing. As a result of enhanced light absorptivity with pollution development, BC forcing efficiency could increase by 20% during polluted period. Our work identified the importance of BC on radiative forcing under polluted environment, which is determined by not only the increase of BC mass concentration, but also the enhancement of BC forcing efficiency due to more coating materials.

A Protective Mechanism of Visible Red Light in Normal Human Dermal Fibroblasts: Enhancement of GADD45A-Mediated DNA Repair Activity.

PubMed

Kim, Yeo Jin; Kim, Hyoung-June; Kim, Hye Lim; Kim, Hyo Jeong; Kim, Hyun Soo; Lee, Tae Ryong; Shin, Dong Wook; Seo, Young Rok

2017-02-01

The phototherapeutic effects of visible red light on skin have been extensively investigated, but the underlying biological mechanisms remain poorly understood. We aimed to elucidate the protective mechanism of visible red light in terms of DNA repair of UV-induced oxidative damage in normal human dermal fibroblasts. The protective effect of visible red light on UV-induced DNA damage was identified by several assays in both two-dimensional and three-dimensional cell culture systems. With regard to the protective mechanism of visible red light, our data showed alterations in base excision repair mediated by growth arrest and DNA damage inducible, alpha (GADD45A). We also observed an enhancement of the physical activity of GADD45A and apurinic/apyrimidinic endonuclease 1 (APE1) by visible red light. Moreover, UV-induced DNA damages were diminished by visible red light in an APE1-dependent manner. On the basis of the decrease in GADD45A-APE1 interaction in the activating transcription factor-2 (ATF2)-knockdown system, we suggest a role for ATF2 modulation in GADD45A-mediated DNA repair upon visible red light exposure. Thus, the enhancement of GADD45A-mediated base excision repair modulated by ATF2 might be a potential protective mechanism of visible red light. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Synergistic interactions between temporal coupling of complex light and magnetic pulses upon melanoma cell proliferation and planarian regeneration.

PubMed

Murugan, Nirosha J; Karbowski, Lukasz M; Persinger, Michael A

2017-01-01

Synergisms between a physiologically patterned magnetic field that is known to enhance planarian growth and suppress proliferation of malignant cells in culture and three light emitting diode (LED) generated visible wavelengths (blue, green, red) upon planarian regeneration and melanoma cell numbers were discerned. Five days of hourly exposures to either a physiologically patterned (2.5-5.0 μT) magnetic field, one of three wavelengths (3 kLux) or both treatments simultaneously indicated that red light (680 nm), blue light (470 nm) or the magnetic field significantly facilitated regeneration of planarian compared to sham field exposed planarian. Presentation of both light and magnetic field conditions enhanced the effect. Whereas the blue and red light diminished the growth of malignant (melanoma) cells, the effect was not as large as that produced by the magnetic field. Only the paired presentation of the blue light and magnetic field enhanced the suppression. On the other hand, the changes following green light (540 nm) exposure did not differ from the control condition and green light presented with the magnetic field eliminated its effects for both the planarian and melanoma cells. These results indicate specific colors affect positive adaptation that is similar to weak, physiologically patterned frequency modulated (8-24 Hz) magnetic fields and that the two forms of energy can synergistically summate or cancel.

Enhancing the effectiveness of the U.S. Army's participation in medical diplomacy: implications from a case study in Trinidad.

PubMed

Haims, Marla C; Duber, Herbert C; Chang, Lie-Ping

2014-06-01

Medical diplomacy is a complex, yet increasingly important strategy of the U.S. government. In this article, we present a unique program that was jointly developed by the U.S. Army Reserves 807 th Medical Deployment Support Command and the Trinidad Ministry of Health to address the large backlog of untreated cataracts in Trinidad and Tobago. This partnership evolved over time, but began with a commitment to help address a critical public health issue as determined by the host country, with investment in both local capacity and attention towards sustainability. The 807 th Medical Deployment Support Command utilized its connection to the military and civilian worlds, bringing in outside expertise and a long-term university partner allowing for sustainability without protracted U.S. government support. This program resulted in multiple positive outcomes, including building a strong partnership with a key U.S. interest; enhancing the legitimacy of the Trinidadian government through the development of a sustainable cataract program; and providing a platform for the United States to be seen by the Trinidadian public in a very positive light. This new model for medical diplomacy may have significant benefit for both the host country and U.S. government, and deserves further evaluation in other contexts. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

77 FR 38375 - Advisory Circular (AC) 150/5345-53D, Airport Lighting Equipment Certification Program; Proposed...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-27

...The FAA proposes to replace AC150/5345-53C with AC150/5345-53D to clarify the criteria under the Airport Lighting Equipment Certification Program (ALECP) for acceptance of an organization as a third party certification body (third party certifier) and how manufacturers may get equipment qualified under the program. The Secretary of Transportation is providing notice in the Federal Register of, and an opportunity for public comment on AC150/5345-53D, Airport Lighting Equipment Certification Program.

Phenol-photodegradation on ZrO2. Enhancement by semiconductors.

PubMed

Karunakaran, C; Dhanalakshmi, R; Gomathisankar, P

2012-06-15

On illumination with light of wavelength 365 nm phenol undergoes degradation on the surface of ZrO(2). The rate of degradation enhances linearly with the concentration of phenol and also the light intensity but decreases with increase of pH. The photonic efficiency of degradation is higher with illumination at 254 nm than with 365 nm. The diffuse reflectance spectral study suggests phenol-sensitized activation of ZrO(2) with 365 nm light. TiO(2), Fe(2)O(3), CuO, ZnO, ZnS, Nb(2)O(5) and CdO particles enhance the photodegradation on ZrO(2), indicating inter-particle charge-transfer. Determination of size of the particles under suspension, by light scattering technique, shows agglomeration of particles supporting the proposition of charge-transfer between particles. Copyright © 2012 Elsevier B.V. All rights reserved.

Integral imaging based light field display with enhanced viewing resolution using holographic diffuser

NASA Astrophysics Data System (ADS)

Yan, Zhiqiang; Yan, Xingpeng; Jiang, Xiaoyu; Gao, Hui; Wen, Jun

2017-11-01

An integral imaging based light field display method is proposed by use of holographic diffuser, and enhanced viewing resolution is gained over conventional integral imaging systems. The holographic diffuser is fabricated with controlled diffusion characteristics, which interpolates the discrete light field of the reconstructed points to approximate the original light field. The viewing resolution can thus be improved and independent of the limitation imposed by Nyquist sampling frequency. An integral imaging system with low Nyquist sampling frequency is constructed, and reconstructed scenes of high viewing resolution using holographic diffuser are demonstrated, verifying the feasibility of the method.

Glass-wool study of laser-induced spin currents en route to hyperpolarized Cs salt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishikawa, Kiyoshi

2011-07-15

The nuclear spin polarization of optically pumped Cs atoms flows to the surface of Cs hydride in a vapor cell. A fine glass wool lightly coated with the salt helps greatly increase the surface area in contact with the pumped atoms and enhance the spin polarization of the salt nuclei. Even though the glass wool randomly scatters the pump light, the atomic vapor can be polarized with unpolarized light in a magnetic field. The measured enhancement in the salt enables study of the polarizations of light and atomic nuclei very near the salt surface.

Phonon-Mediated Exciton Stark Effect Enhanced by a Static Electric Field

NASA Astrophysics Data System (ADS)

Ivanov, A. L.

1997-03-01

The optical properties of semiconductor QW's change in the presence of coherent pump light. The exciton (phonon-mediated, biexciton-mediated, etc.) optical Stark effect is an effective shift of the exciton level that follow dynamically the intensity I0 ~= 0.1 div 1 GW/cm^2 of the pump light. In the present work we develop a theory of a low-intensity electric-field enhanced phonon-mediated optical Stark effect in polar semiconductors and semiconductor microstructures. The main point is that the exciton - LO-phonon Fröhlich interaction can be strongly enhanced by a (quasi-) static electric field F which polarizes the exciton in the geometry F | k | p, where k and p are the wavevectors of the pump and probe light, respectively. The electric field enhancement of spontaneous Raman scattering has been already analyzed (E. Burstein et al., 1971). Even a moderate electric field F ~= 10^3 V/cm reduces the intensity of the pump light to I0 ~= 1 div 10 MW/cm^2. Moreover, the phonon-mediated Stark effect enhanced by a static electric field F allow us to realize the both red and blue dynamical shifts of the exciton level.

Flexible organic light-emitting diodes with enhanced light out-coupling efficiency fabricated on a double-sided nanotextured substrate.

PubMed

Luo, Yu; Wang, Chunhui; Wang, Li; Ding, Yucheng; Li, Long; Wei, Bin; Zhang, Jianhua

2014-07-09

High-efficiency organic light-emitting diodes (OLEDs) have generated tremendous research interest. One of the exciting possibilities of OLEDs is the use of flexible plastic substrates, which unfortunately have a mismatching refractive index compared with the conventional ITO anode and the air. To unlock the light loss on flexible plastic, we report a high-efficiency flexible OLED directly fabricated on a double-sided nanotextured polycarbonate substrate by thermal nanoimprint lithography. The template for the nanoimprint process is a replicate from a silica arrayed with nanopillars and fabricated by ICP etching through a SiO2 colloidal spheres mask. It has been shown that with the internal quasi-periodical scattering gratings the efficiency enhancement can reach 50% for a green light OLED, and with an external antireflection structure, the normal transmittance is increased from 89% to 94% for paraboloid-like pillars. The OLED directly fabricated on the double-sided nanotextured polycarbonate substrate has reached an enhancing factor of ∼2.8 for the current efficiency.

Multiscale Modeling of Plasmon-Enhanced Power Conversion Efficiency in Nanostructured Solar Cells.

PubMed

Meng, Lingyi; Yam, ChiYung; Zhang, Yu; Wang, Rulin; Chen, GuanHua

2015-11-05

The unique optical properties of nanometallic structures can be exploited to confine light at subwavelength scales. This excellent light trapping is critical to improve light absorption efficiency in nanoscale photovoltaic devices. Here, we apply a multiscale quantum mechanics/electromagnetics (QM/EM) method to model the current-voltage characteristics and optical properties of plasmonic nanowire-based solar cells. The QM/EM method features a combination of first-principles quantum mechanical treatment of the photoactive component and classical description of electromagnetic environment. The coupled optical-electrical QM/EM simulations demonstrate a dramatic enhancement for power conversion efficiency of nanowire solar cells due to the surface plasmon effect of nanometallic structures. The improvement is attributed to the enhanced scattering of light into the photoactive layer. We further investigate the optimal configuration of the nanostructured solar cell. Our QM/EM simulation result demonstrates that a further increase of internal quantum efficiency can be achieved by scattering light into the n-doped region of the device.

Enhancing the Photovoltaic Performance of Perovskite Solar Cells with a Down-Conversion Eu-Complex.

PubMed

Jiang, Ling; Chen, Wangchao; Zheng, Jiawei; Zhu, Liangzheng; Mo, Li'e; Li, Zhaoqian; Hu, Linhua; Hayat, Tasawar; Alsaedi, Ahmed; Zhang, Changneng; Dai, Songyuan

2017-08-16

Organometal halide perovskite solar cells (PSCs) have shown high photovoltaic performance but poor utilization of ultraviolet (UV) irradiation. Lanthanide complexes have a wide absorption range in the UV region and they can down-convert the absorbed UV light into visible light, which provides a possibility for PSCs to utilize UV light for higher photocurrent, efficiency, and stability. In this study, we use a transparent luminescent down-converting layer (LDL) of Eu-4,7-diphenyl-1,10-phenanthroline (Eu-complex) to improve the light utilization efficiency of PSCs. Compared with the uncoated PSC, the PSC coated with Eu-complex LDL on the reverse of the fluorine-doped tin oxide glass displayed an enhancement of 11.8% in short-circuit current density (J sc ) and 15.3% in efficiency due to the Eu-complex LDL re-emitting UV light (300-380 nm) in the visible range. It is indicated that the Eu-complex LDL plays the role of enhancing the power conversion efficiency as well as reducing UV degradation for PSCs.

Light Pollution and Wildlife

NASA Astrophysics Data System (ADS)

Duffek, J.

2008-12-01

for Educational Program IYA Dark Skies Education Session Fall American Geophysical Union San Francisco, December 15-19, 2008 Light Pollution and Wildlife This is a very exciting time to be a part of the mission to keep the nighttime skies natural. The International Year of Astronomy (IYA) 2009 is developing programs for all areas of Dark Skies Awareness. For many years the issue of light pollution focused on the impact to the astronomy industry. While this is an important area, research has shown that light pollution negatively impacts wildlife, their habitat, human health, and is a significant waste of energy. Since the message and impact of the effects of light pollution are much broader now, the message conveyed to the public must also be broader. Education programs directed at youth are a new frontier to reach out to a new audience about the adverse effects of too much artificial light at night. The International Dark-Sky Association (IDA) has developed educational presentations using the National Science Teachers Association Education Standards. These programs focus on youth between the ages of 5 to 17exploring new territory in the education of light pollution. The IDA education programs are broken down into three age groups; ages 5-9, 8-13, 12 and older. The presentations come complete with PowerPoint slides, discussion notes for each slide, and workbooks including age appropriate games to keep young audiences involved. A new presentation reflects the growing area of interest regarding the effects of too much artificial light at night on wildlife. This presentation outlines the known problems for ecosystems caused by artificial light at night. Insects are attracted to artificial lights and may stay near that light all night. This attraction interferes with their ability to migrate, mate, and look for food. Such behavior leads to smaller insect populations. Fewer insects in turn affect birds and bats, because they rely on insects as a food source. The IDA education programs show children how all of these issues are interrelated. Insects are not the only organisms adversely affected by light at night. Reptiles, mammals, birds and amphibians are also negatively impacted. All creatures have a biological clock which determines when they rest, hunt, migrate, and mate. Bright lights create confusion in many species by disrupting this internal biological clock. IDA presents the solutions to these problems as quality outdoor lighting, and the presentations show examples of dark sky friendly lighting. The youth audience is an excellent venue for wildlife education outreach. The IDA youth education programs are completed and ready for use. They can be used by professional teachers, parents, community organizers, or anyone advocating to keep the skies natural. This is a great time to promote the win-win benefits of good nighttime lighting.

A Comparison of Honey Bee-Collected Pollen From Working Agricultural Lands Using Light Microscopy and ITS Metabarcoding.

PubMed

Smart, M D; Cornman, R S; Iwanowicz, D D; McDermott-Kubeczko, M; Pettis, J S; Spivak, M S; Otto, C R V

2017-02-01

Taxonomic identification of pollen has historically been accomplished via light microscopy but requires specialized knowledge and reference collections, particularly when identification to lower taxonomic levels is necessary. Recently, next-generation sequencing technology has been used as a cost-effective alternative for identifying bee-collected pollen; however, this novel approach has not been tested on a spatially or temporally robust number of pollen samples. Here, we compare pollen identification results derived from light microscopy and DNA sequencing techniques with samples collected from honey bee colonies embedded within a gradient of intensive agricultural landscapes in the Northern Great Plains throughout the 2010-2011 growing seasons. We demonstrate that at all taxonomic levels, DNA sequencing was able to discern a greater number of taxa, and was particularly useful for the identification of infrequently detected species. Importantly, substantial phenological overlap did occur for commonly detected taxa using either technique, suggesting that DNA sequencing is an appropriate, and enhancing, substitutive technique for accurately capturing the breadth of bee-collected species of pollen present across agricultural landscapes. We also show that honey bees located in high and low intensity agricultural settings forage on dissimilar plants, though with overlap of the most abundantly collected pollen taxa. We highlight practical applications of utilizing sequencing technology, including addressing ecological issues surrounding land use, climate change, importance of taxa relative to abundance, and evaluating the impact of conservation program habitat enhancement efforts. Published by Oxford University Press on behalf of Entomological Society of America 2016. This work is written by US Government employees and is in the public domain in the US.

7 CFR 1467.9 - Wetlands Reserve Enhancement Program.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 10 2011-01-01 2011-01-01 false Wetlands Reserve Enhancement Program. 1467.9 Section... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS WETLANDS RESERVE PROGRAM § 1467.9 Wetlands Reserve Enhancement Program. (a) Wetlands Reserve Enhancement Program (WREP). (1) The...

Changes in Energy Intake and Diet Quality during an 18-Month Weight-Management Randomized Controlled Trial in Adults with Intellectual and Developmental Disabilities.

PubMed

Ptomey, Lauren T; Steger, Felicia L; Lee, Jaehoon; Sullivan, Debra K; Goetz, Jeannine R; Honas, Jeffery J; Washburn, Richard A; Gibson, Cheryl A; Donnelly, Joseph E

2018-06-01

Previous research indicates that individuals with intellectual and developmental disabilities (IDDs) are at risk for poor diet quality. The purpose of this secondary analysis was to determine whether two different weight-loss diets affect energy intake, macronutrient intake, and diet quality as measured by the Healthy Eating Index-2010 (HEI-2010) during a 6-month weight-loss period and 12-month weight-management period, and to examine differences in energy intake, macronutrient intake, and HEI-2010 between groups. Overweight/obese adults with IDDs took part in an 18-month randomized controlled trial and were assigned to either an enhanced Stop Light Diet utilizing portion-controlled meals or a conventional diet consisting of reducing energy intake and following the 2010 Dietary Guidelines for Americans. Proxy-assisted 3-day food records were collected at baseline, 6 months, and 18 months, and were analyzed using Nutrition Data System for Research software. HEI-2010 was calculated using the data from Nutrition Data System for Research. The study took place from June 2011 through May 2014 in the greater Kansas City metropolitan area. This was a secondary analysis of a weight-management intervention for adults with IDDs randomized to an enhanced Stop Light Diet or conventional diet, to examine differences in energy intake, macronutrient intake, and HEI-2010 across time and between groups. Independent- and paired-samples t tests and general mixed modeling for repeated measures were performed to examine group differences and changes at baseline, 6 months, and 18 months between the enhanced Stop Light Diet and conventional diet groups. One hundred and forty six participants (57% female, mean±standard deviation age=36.2±12.0 years) were randomized to either the enhanced Stop Light Diet or conventional diet group (77 enhanced Stop Light Diet, 69 conventional diet) and provided data for analysis at baseline, 124 completed the 6-month weight-loss period, and 101 completed the 18-month study. Participants on the enhanced Stop Light Diet diet significantly reduced energy intake at 6 and 18 months (both P<0.001), but those on the conventional diet did not (both P=0.13). However, when accounting for age, sex, race, education level, and support level (mild vs moderate IDD), there was a significant decrease during the 18-month intervention in energy intake for the enhanced Stop Light Diet and conventional diet groups combined (P<0.01 for time effect), but no significant group difference in this change (P=0.39 for group-by-time interaction). There was no significant change in total HEI-2010 score at 6 and 18 months (P=0.05 and P=0.38 for the enhanced Stop Light Diet group; P=0.22 and P=0.17 for the conventional diet group), and no significant group difference at 6 and 18 months (P=0.08 and P=0.42). However, when participants' age, sex, race, education level, and support level were accounted for, mixed modeling indicated a significant increase in total HEI-2010 scores for the enhanced Stop Light Diet and conventional diet groups combined during the 18-month intervention (P=0.01 for time effect). The results of this study found that after controlling for demographic factors, individuals with IDDs can decrease their energy intake and increase their diet quality, with no significant differences between the enhanced Stop Light Diet and conventional diet groups. Copyright © 2018 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Observation of the enhanced backscattering of light by the end of a tilted dielectric cylinder owing to the caustic merging transition

NASA Astrophysics Data System (ADS)

Marston, Philip L.; Zhang, Yibing; Thiessen, David B.

2003-01-01

The scattering of light by obliquely illuminated circular dielectric cylinders was previously demonstrated to be enhanced by a merger of Airy caustics at a critical tilt angle. [Appl. Opt. 37, 1534 (1998)]. A related enhancement is demonstrated here for backward and near-backward scattering for cylinders cut with a flat end perpendicular to the cylinder's axis. It is expected that merged caustics will enhance the backscattering by clouds of randomly oriented circular cylinders that have appropriately flat ends.

Flow in porous media, phase and ultralow interfacial tensions: Mechanisms of enhanced petroleum recovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, H.T.; Scriven, L.E.

1991-07-01

A major program of university research, longer-ranged and more fundamental in approach than industrial research, into basic mechanisms of enhancing petroleum recovery and into underlying physics, chemistry, geology, applied mathematics, computation, and engineering science has been built at Minnesota. The original focus was surfactant-based chemical flooding, but the approach taken was sufficiently fundamental that the research, longer-ranged than industrial efforts, has become quite multidirectional. Topics discussed are volume controlled porosimetry; fluid distribution and transport in porous media at low wetting phase saturation; molecular dynamics of fluids in ultranarrow pores; molecular dynamics and molecular theory of wetting and adsorption; new numericalmore » methods to handle initial and boundary conditions in immiscible displacement; electron microscopy of surfactant fluid microstructure; low cost system for animating liquid crystallites viewed with polarized light; surfaces of constant mean curvature with prescribed contact angle.« less

Development of therapeutic Au-methylene blue nanoparticles for targeted photodynamic therapy of cervical cancer cells.

PubMed

Yu, Jiashing; Hsu, Che-Hao; Huang, Chih-Chia; Chang, Po-Yang

2015-01-14

Photodynamic therapy (PDT) involves the cellular uptake of a photosensitizer (PS) combined with oxygen molecules and light at a specific wavelength to be able to trigger cancer cell death via the apoptosis pathway, which is less harmful and has less inflammatory side effect than necrosis. However, the traditional PDT treatment has two main deficiencies: the dark toxicity of the PS and the poor selectivity of the cellular uptake of PS between the target cells and normal tissues. In this work, methylene blue (MB), a known effective PS, combined with Au nanoparticles (NPs) was prepared using an intermolecular interaction between a polystyrene-alt-maleic acid (PSMA) layer on the Au NPs and MB. The Au@polymer/MB NPs produced a high quantum yield of singlet oxygen molecules, over 50% as much as that of free MB, when they were excited by a dark red light source at 660 nm, but without significant dark toxicity. Furthermore, transferrin (Tf) was conjugated on the Au@polymer/MB NPs via an EDC/NHS reaction to enhance the selectivity to HeLa cells compared to 3T3 fibroblasts. With a hand-held single laser treatment (32 mW/cm) for 4 min, the new Au@polymer/MB-Tf NPs showed a 2-fold enhancement of PDT efficiency toward HeLa cells over the use of free MB at 4 times dosage. Cellular staining examinations showed that the HeLa cells reacted with Au@polymer/MB-Tf NPs and the 660 nm light excitation triggered PDT, which caused the cells to undergo apoptosis ("programmed" cell death). We propose that applying this therapeutic Au@polymer/MB-Tf nanoagent is facile and safe for delivery and cancer cell targeting to simultaneously minimize side effects and accomplish a significant enhancement in photodynamic therapeutic efficiency toward next-generation nanomedicine development.

Concentrating light in Cu(In,Ga)Se2 solar cells

NASA Astrophysics Data System (ADS)

Schmid, M.; Yin, G.; Song, M.; Duan, S.; Heidmann, B.; Sancho-Martinez, D.; Kämmer, S.; Köhler, T.; Manley, P.; Lux-Steiner, M. Ch.

2016-09-01

Light concentration has proven beneficial for solar cells, most notably for highly efficient but expensive absorber materials using high concentrations and large scale optics. Here we investigate light concentration for cost efficient thinfilm solar cells which show nano- or microtextured absorbers. Our absorber material of choice is Cu(In,Ga)Se2 (CIGSe) which has a proven stabilized record efficiency of 22.6% and which - despite being a polycrystalline thin-film material - is very tolerant to environmental influences. Taking a nanoscale approach, we concentrate light in the CIGSe absorber layer by integrating photonic nanostructures made from dielectric materials. The dielectric nanostructures give rise to resonant modes and field localization in their vicinity. Thus when inserted inside or adjacent to the absorber layer, absorption and efficiency enhancement are observed. In contrast to this internal absorption enhancement, external enhancement is exploited in the microscale approach: mm-sized lenses can be used to concentrate light onto CIGSe solar cells with lateral dimensions reduced down to the micrometer range. These micro solar cells come with the benefit of improved heat dissipation compared to the large scale concentrators and promise compact high efficiency devices. Both approaches of light concentration allow for reduction in material consumption by restricting the absorber dimension either vertically (ultra-thin absorbers for dielectric nanostructures) or horizontally (micro absorbers for concentrating lenses) and have significant potential for efficiency enhancement.

Concentrating light in Cu(In,Ga)Se2 solar cells

NASA Astrophysics Data System (ADS)

Schmid, Martina; Yin, Guanchao; Song, Min; Duan, Shengkai; Heidmann, Berit; Sancho-Martinez, Diego; Kämmer, Steven; Köhler, Tristan; Manley, Phillip; Lux-Steiner, Martha Ch.

2017-01-01

Light concentration has proven beneficial for solar cells, most notably for highly efficient but expensive absorber materials using high concentrations and large scale optics. Here, we investigate the light concentration for cost-efficient thin-film solar cells that show nano- or microtextured absorbers. Our absorber material of choice is Cu(In,Ga)Se2 (CIGSe), which has a proven stabilized record efficiency of 22.6% and which-despite being a polycrystalline thin-film material-is very tolerant to environmental influences. Taking a nanoscale approach, we concentrate light in the CIGSe absorber layer by integrating photonic nanostructures made from dielectric materials. The dielectric nanostructures give rise to resonant modes and field localization in their vicinity. Thus, when inserted inside or adjacent to the absorber layer, absorption and efficiency enhancement are observed. In contrast to this internal absorption enhancement, external enhancement is exploited in the microscaled approach: mm-sized lenses can be used to concentrate light onto CIGSe solar cells with lateral dimensions reduced down to the micrometer range. These micro solar cells come with the benefit of improved heat dissipation compared with the large scale concentrators and promise compact high-efficiency devices. Both approaches of light concentration allow for reduction in material consumption by restricting the absorber dimension either vertically (ultrathin absorbers for dielectric nanostructures) or horizontally (microabsorbers for concentrating lenses) and have significant potential for efficiency enhancement.

Cationic (V, Y)-codoped TiO2 with enhanced visible light induced photocatalytic activity: A combined experimental and theoretical study

NASA Astrophysics Data System (ADS)

Khan, Matiullah; Cao, Wenbin

2013-11-01

To employ TiO2 as an efficient photocatalyst, high reactivity under visible light and improved separation of photoexcited carriers are required. An effective co-doping approach is applied to modify the photocatalytic properties of TiO2 by doping vanadium (transition metal) and yttrium (rare earth element). V and/or Y codoped TiO2 was prepared using hydrothermal method without any post calcination for crystallization. Based on density functional theory, compensated and noncompensated V, Y codoped TiO2 models were constructed and their structural, electronic, and optical properties were calculated. Through combined experimental characterization and theoretical modeling, V, Y codoped TiO2 exhibited high absorption coefficient with enhanced visible light absorption. All the prepared samples showed pure anatase phase and spherical morphology with uniform particle distribution. Electronic band structure demonstrates that V, Y codoping drastically reduced the band gap of TiO2. It is found that both the doped V and Y exist in the form of substitutional point defects replacing Ti atom in the lattice. The photocatalytic activity, evaluated by the degradation of methyl orange, displays that the codoped TiO2 sample exhibits enhanced visible light photocatalytic activity. The synergistic effects of V and Y drastically improved the Brunauer-Emmett-Teller specific surface area, visible light absorption, and electron-hole pair's separation leading to the enhanced visible light catalytic activity.

FY2014 Propulsion Materials R&D Annual Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines [ACE], Advanced Power Electronics and Electrical Machinesmore » [APEEM], and fuels) teams to develop strategies that overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.« less

FY2015 Propulsion Materials Annual Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines [ACE], Advanced Power Electronics and Electrical Machinesmore » [APEEM], and fuels) teams to develop strategies that overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.« less

A Comparison of Blue Light and Caffeine Effects on Cognitive Function and Alertness in Humans

PubMed Central

Beaven, C. Martyn; Ekström, Johan

2013-01-01

The alerting effects of both caffeine and short wavelength (blue) light have been consistently reported. The ability of blue light to enhance alertness and cognitive function via non-image forming neuropathways have been suggested as a non-pharmacological countermeasure for drowsiness across a range of occupational settings. Here we compare and contrast the alerting and psychomotor effects of 240 mg of caffeine and a 1-h dose of ~40 lx blue light in a non-athletic population. Twenty-one healthy subjects performed a computer-based psychomotor vigilance test before and after each of four randomly assigned trial conditions performed on different days: white light/placebo; white light/240 mg caffeine; blue light/placebo; blue light/240 mg caffeine. The Karolinska Sleepiness Scale was used to assess subjective measures of alertness. Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants. Overall, blue light and caffeine demonstrated distinct effects on aspects of psychomotor function and have the potential to positively influence a range of settings where cognitive function and alertness are important. Specifically, despite the widespread use of caffeine in competitive sporting environments, the possible impact of blue light has received no research attention. PMID:24282477

Signal-enhancement reflective pulse oximeter with Fresnel lens

NASA Astrophysics Data System (ADS)

Chung, Shuang-Chao; Sun, Ching-Cherng

2016-09-01

In this paper, a new reflective pulse oximeter is proposed and demonstrated with implanting a Fresnel lens, which enhances the reflected signal. An optical simulation model incorporated with human skin characteristics is presented to evaluate the capability of the Fresnel lens. In addition, the distance between the light emitting diode and the photodiode is optimized. Compared with the other reflective oximeters, the reflected signal light detected by the photodiode is enhanced to more than 140%.

10 CFR 490.203 - Light Duty Alternative Fueled Vehicle Plan.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Light Duty Alternative Fueled Vehicle Plan. 490.203 Section 490.203 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ALTERNATIVE FUEL TRANSPORTATION PROGRAM Mandatory State Fleet Program § 490.203 Light Duty Alternative Fueled Vehicle Plan. (a) General Provisions...

10 CFR 490.203 - Light Duty Alternative Fueled Vehicle Plan.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Light Duty Alternative Fueled Vehicle Plan. 490.203 Section 490.203 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ALTERNATIVE FUEL TRANSPORTATION PROGRAM Mandatory State Fleet Program § 490.203 Light Duty Alternative Fueled Vehicle Plan. (a) General Provisions...

10 CFR 490.203 - Light Duty Alternative Fueled Vehicle Plan.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Light Duty Alternative Fueled Vehicle Plan. 490.203 Section 490.203 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ALTERNATIVE FUEL TRANSPORTATION PROGRAM Mandatory State Fleet Program § 490.203 Light Duty Alternative Fueled Vehicle Plan. (a) General Provisions...

10 CFR 490.203 - Light Duty Alternative Fueled Vehicle Plan.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Light Duty Alternative Fueled Vehicle Plan. 490.203 Section 490.203 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ALTERNATIVE FUEL TRANSPORTATION PROGRAM Mandatory State Fleet Program § 490.203 Light Duty Alternative Fueled Vehicle Plan. (a) General Provisions...

10 CFR 490.203 - Light Duty Alternative Fueled Vehicle Plan.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Light Duty Alternative Fueled Vehicle Plan. 490.203 Section 490.203 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ALTERNATIVE FUEL TRANSPORTATION PROGRAM Mandatory State Fleet Program § 490.203 Light Duty Alternative Fueled Vehicle Plan. (a) General Provisions...

LED roadway luminaires evaluation.

DOT National Transportation Integrated Search

2011-12-01

This research explores whether LEDroadway luminaire technologies are a viable future solution to providing roadway lighting. Roadway lighting enhances highway safety and traffic flow during limited lighting conditions. The purpose of this evaluation ...

Technology-Based Orientation Programs to Support Indoor Travel by Persons with Moderate Alzheimer's Disease: Impact Assessment and Social Validation

ERIC Educational Resources Information Center

Lancioni, Giulio E.; Perilli, Viviana; O'Reilly, Mark F.; Singh, Nirbhay N.; Sigafoos, Jeff; Bosco, Andrea; Caffo, Alessandro O.; Picucci, Luciana; Cassano, Germana; Groeneweg, Jop

2013-01-01

The present study (a) extended the assessment of an orientation program involving auditory cues (i.e., verbal messages automatically presented from the destinations) with five patients with Alzheimer's disease, (b) compared the effects of this program with those of a program with light cues (i.e., a program in which strobe lights were used instead…

Session 21.7 - Education Programs Promoting Light Pollution Awareness and IYL2015

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2016-10-01

By proclaiming the IYL2015, the United Nations recognized the importance of light and light based technology in the lives of the citizens of the world and for the development of global society on many levels. Light and application of light science and technology are vital for existing and future advances in many scientific areas and culture. Light is a key element in astronomy: as astronomers, it is what we study and makes our science possible, but it is also what threatens our observations when it is set-off from the ground (light pollution). The UN-designated year 2015 represented a magnificent and unique opportunity for the global astronomical community to disseminate these messages and raise the awareness of the importance and preservation of dark skies for heritage and the natural environment. As such, the International Year of Light served as a launching pad for several projects during 2015. Two other projects with equally as impressive programs are highlighted and begin the narrative for this section on public education and outreach programs on light pollution issues and solutions.

A superior architecture of brightness enhancement for display backlighting

NASA Astrophysics Data System (ADS)

Dross, Oliver; Parkyn, William A.; Chaves, Julio; Falicoff, Waqidi; Miñano, Juan Carlos; Benitez, Pablo; Alvarez, Roberto

2006-08-01

Brightness enhancement of backlighting for displays is typically achieved via crossed micro prismatic films that are introduced between a backlight unit and a transmissive (LCD) display. Prismatic films let pass light only into a restricted angular range, while, in conjunction with other reflective elements below the backlight, all other light is recycled within the backlight unit, thereby increasing the backlight luminance. This design offers no free parameters to influence the resulting light distribution and suffers from insufficient stray light control. A novel strategy of light recycling is introduced, using a microlens array in conjunction with a hole array in a reflective surface, that can provide higher luminance, superior stray light control, and can be designed to meet almost any desired emission pattern. Similar strategies can be applied to mix light from different colored LEDs being mounted upside down to shine into a backlight unit.

Light beam shaping for collimated emission from white organic light-emitting diodes using customized lenticular microlens arrays structure

NASA Astrophysics Data System (ADS)

Zhou, Lei; Bai, Gui-Lin; Guo, Xin; Shen, Su; Ou, Qing-Dong; Fan, Yuan-Yuan

2018-05-01

We present a design approach to realizing a desired collimated planar incoherent light source (CPILS) by incorporating lenticular microlens arrays (LMLAs) onto the substrates of discrete white organic light-emitting diode (WOLED) light sources and demonstrate the effectiveness of this method in collimated light beam shaping and luminance enhancement simultaneously. The obtained collimated WOLED light source shows enhanced luminance by a factor of 2.7 compared with that of the flat conventional device at the normal polar angle and, more importantly, exhibits a narrowed angular emission with a full-width at half-maximum (FWHM) of ˜33.6°. We anticipate that the presented strategy could provide an alternative way for achieving the desired large scale CPILS, thereby opening the door to many potential applications, including LCD backlights, three-dimensional displays, car headlights, and so forth.

Light-extraction efficiency and forward voltage in GaN-based light-emitting diodes with different patterns of V-shaped pits

NASA Astrophysics Data System (ADS)

Wang, Min-Shuai; Huang, Xiao-Jing

2013-08-01

We present a new method of making a textured V-pit surface for improving the light extraction efficiency in GaN-based light-emitting diodes and compare it with the usual low-temperature method for p-GaN V-pits. Three types of GaN-based light-emitting diodes (LEDs) with surface V-pits in different densities and regions were grown by metal—organic chemical vapor deposition. We achieved the highest output power and lowest forward voltage values with the p-InGaN V-pit LED. The V-pits enhanced the light output power values by 1.45 times the values of the conventional LED owing to an enhancement of the light scattering probability and an effective reduction of Mg-acceptor activation energy. Moreover, this new technique effectively solved the higher forward voltage problem of the usual V-pit LED.

LED roadway luminaires evaluation.

DOT National Transportation Integrated Search

2012-02-01

This research explores whether LED roadway luminaire technologies are a viable future solution to providing roadway lighting. Roadway lighting : enhances highway safety and traffic flow during limited lighting conditions. The purpose of this evaluati...

Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

NASA Astrophysics Data System (ADS)

Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

2013-12-01

Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

PubMed Central

2013-01-01

Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail. PMID:24369051

Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors.

PubMed

Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

2013-12-26

Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

Photocurrent enhancement mechanisms in bilayer nanofilm-based ultraviolet photodetectors made from ZnO and ZnS spherical nanoshells

PubMed Central

2014-01-01

Hollow-sphere bilayer nanofilm-based ultraviolet light photodetectors made from ZnO and ZnS spherical nanoshells show enhanced photocurrent, which are comparable to or even better than those of other semiconductor nanostructures with different shapes. In this work, the photocurrent enhancement mechanisms of these bilayer nanofilm-based ultraviolet light photodetectors are explained, which could be attributed to the strong light absorption based on the whispering gallery mode resonances, the separation of the photogenerated carriers through the internal electric field within the bilayer nanofilms, the hopping-like electrical transport, and the effective charge injection from Cr/Au contacts to the nanofilms. PMID:25136287

Self-organized nitrogen and fluorine co-doped titanium oxide nanotube arrays with enhanced visible light photocatalytic performance.

PubMed

Li, Qi; Shang, Jian Ku

2009-12-01

Self-organized nitrogen and fluorine co-doped titanium oxide (TiONF) nanotube arrays were created by anodizing titanium foil in a fluoride and ammoniate-based electrolyte, followed by calcination of the amorphous nanotube arrays under a nitrogen protective atmosphere for crystallization. TiONF nanotube arrays were found to have enhanced visible light absorption capability and photodegradation efficiency on methylene blue under visible light illumination over the TiO(2) nanotube arrays. The enhancement was dependent on both the nanotube structural architecture and the nitrogen and fluorine co-doping effect. TiONF nanotube arrays promise a wide range of technical applications, especially for environmental applications and solar cell devices.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR LIGHT PEN OPERATION AND VERIFICATION OF SCANNED BAR CODES (UA-D-33.0)

EPA Science Inventory

The purpose of this SOP is to define the steps needed to operate the light pens, and verify the values produced by light pens used in the Arizona NHEXAS project and the Border study. Keywords: data; equipment; light pens.

The U.S.-Mexico Border Program is sponsored by the Envir...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coleman, Andrena

The Ida H. Goode Gymnasium was constructed in 1964 to serve as a focal point for academics, student recreation, and health and wellness activities. This 38,000 SF building contains a gymnasium with a stage, swimming pool, eight classrooms, a weight room, six offices and auxiliary spaces for the athletic programs. The gym is located on a 4-acre greenfield, which is slated for improvement and enhancement to future athletics program at Bennett College. The available funding for this project was used to weatherize the envelope of the gymnasium, installation of a new energy-efficient mechanical system, and a retrofit of the existingmore » lighting systems in the building’s interior. The envelope weatherization was completed without disturbing the building’s historic preservation eligibility. The existing heating system was replaced with a new high efficiency condensing system. The new heating system also includes a new Building Automation System which provides additional monitoring. Proper usage of this system will provide additional energy savings. Most of the existing interior lighting fixtures and bulbs were replaced with new LED and high efficiency T-8 bulbs and fixtures. Occupancy sensors were installed in applicable areas. The Ida Goode Gymnasium should experience high electricity and natural gas savings as well as operational/maintenance efficiency increases. The aesthetics of the building was maintained and the overall safety was improved.« less

Hydrologic enforcement of lidar DEMs

USGS Publications Warehouse

Poppenga, Sandra K.; Worstell, Bruce B.; Danielson, Jeffrey J.; Brock, John C.; Evans, Gayla A.; Heidemann, H. Karl

2014-01-01

Hydrologic-enforcement (hydro-enforcement) of light detection and ranging (lidar)-derived digital elevation models (DEMs) modifies the elevations of artificial impediments (such as road fills or railroad grades) to simulate how man-made drainage structures such as culverts or bridges allow continuous downslope flow. Lidar-derived DEMs contain an extremely high level of topographic detail; thus, hydro-enforced lidar-derived DEMs are essential to the U.S. Geological Survey (USGS) for complex modeling of riverine flow. The USGS Coastal and Marine Geology Program (CMGP) is integrating hydro-enforced lidar-derived DEMs (land elevation) and lidar-derived bathymetry (water depth) to enhance storm surge modeling in vulnerable coastal zones.

Engineering development of selective agglomeration: Task 5, Bench- scale process testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-09-01

Under the overall objectives of DOE Contract ``Engineering Development of Selective Agglomeration,`` there were a number of specific objectives in the Task 5 program. The prime objectives of Task 5 are highlighted below: (1) Maximize process performance in pyritic sulfur rejection and BTU recovery, (2) Produce a low ash product, (3) Compare the performance of the heavy agglomerant process based on diesel and the light agglomerant process using heptane, (4) Define optimum processing conditions for engineering design, (5) Provide first-level evaluation of product handleability, and (6) Explore and investigate process options/ideas which may enhance process performance and/or product handleability.

Engineering development of selective agglomeration: Task 5, Bench- scale process testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-09-01

Under the overall objectives of DOE Contract Engineering Development of Selective Agglomeration,'' there were a number of specific objectives in the Task 5 program. The prime objectives of Task 5 are highlighted below: (1) Maximize process performance in pyritic sulfur rejection and BTU recovery, (2) Produce a low ash product, (3) Compare the performance of the heavy agglomerant process based on diesel and the light agglomerant process using heptane, (4) Define optimum processing conditions for engineering design, (5) Provide first-level evaluation of product handleability, and (6) Explore and investigate process options/ideas which may enhance process performance and/or product handleability.

Systematic technology evaluation program for SiC/SiC composite-based accident-tolerant LWR fuel cladding and core structures: Revision 2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katoh, Yutai; Terrani, Kurt A.

2015-08-01

Fuels and core structures in current light water reactors (LWR’s) are vulnerable to catastrophic failure in severe accidents as unfortunately evidenced by the March 2011 Fukushima Dai-ichi Nuclear Power Plant Accident. This vulnerability is attributed primarily to the rapid oxidation kinetics of zirconium alloys in a water vapor environment at very high temperatures. Zr alloys are the primary material in LWR cores except for the fuel itself. Therefore, alternative materials with reduced oxidation kinetics as compared to zirconium alloys are sought to enable enhanced accident-tolerant fuels and cores.

Chinese launch vehicles aim for the commercial market

NASA Astrophysics Data System (ADS)

Clark, Phillip S.

While the Chinese space program appears, in light of information being made available to the West, to be on the verge of substantial expansion, its direction is presently judged to be substantially governed by the international response to China's offers of commercial satellite-launch services. This criterion will be especially relevant to the development of the next-generation of the CZ-2/4L and CZ-3A/4L launch vehicles, each of which employs four strap-on liquid rocket booster units for payload performance enhancement. Attention is presently given to Chinese satellite launch history thus far, and prospective development schedules and performance targets.

The Invisible Universe Online for Teachers - A SOFIA and SIRTF EPO Project

NASA Astrophysics Data System (ADS)

Gauthier, A.; Bennett, M.; Buxner, S.; Devore, E.; Keller, J.; Slater, T.; Thaller, M.; Conceptual Astronomy; Physics Education Research CAPER Team

2003-12-01

The SOFIA and SIRTF EPO Programs have partnered with the Conceptual Astronomy and Physics Education Research (CAPER) Team in designing, evaluating, and facilitating an online program for K-12 teachers to experience multiwavelength astronomy. An aggressive approach to online course design and delivery has resulted in a highly successful learning experience for teacher-participants. Important aspects of the Invisible Universe Online will eventually be used as a part of SOFIA's Airborne Ambassadors Program for pre-flight training of educators. The Invisible Universe Online is delivered via WebCT through the Montana State University National Teacher Enhancement Network (http://btc.montana.edu/). Currently in its fourth semester, the course has served 115 K-12 teachers. This distance learning online class presents our search for astronomical origins and provides an enhanced understanding of how astronomers use all energies of light to unfold the secrets of the universe. We cover the long chain of events from the birth of the universe through the formation of galaxies, stars, and planets by focusing on the scientific questions, technological challenges, and space missions pursuing this search for origins. Through textbook and internet readings, inquiry exploration with interactive java applets, and asynchronous discussions, we help our students achieve the following course goals: develop scientific background knowledge of astronomical objects and phenomena at multiple wavelengths; understand contemporary scientific research questions related to how galaxies formed in the early universe and how stars and planetary systems form and evolve; describe strategies and technologies for using non-visible wavelengths of EM radiation to study various phenomena; and integrate related issues of astronomical science and technology into K-12 classrooms. This course is being developed, evaluated, and offered through the support of SOFIA and SIRTF EPO Programs, two NASA infrared missions associated with the Origins program.

Electronic Two-Transition-Induced Enhancement of Emission Efficiency in Polymer Light-Emitting Diodes

PubMed Central

Chen, Ren-Ai; Wang, Cong; Li, Sheng; George, Thomas F.

2013-01-01

With the development of experimental techniques, effective injection and transportation of electrons is proven as a way to obtain polymer light-emitting diodes (PLEDs) with high quantum efficiency. This paper reveals a valid mechanism for the enhancement of quantum efficiency in PLEDs. When an external electric field is applied, the interaction between a negative polaron and triplet exciton leads to an electronic two-transition process, which induces the exciton to emit light and thus improve the emission efficiency of PLEDs. PMID:28809346

Plasmon-enhanced Electrically Light-emitting from ZnO Nanorod Arrays/p-GaN Heterostructure Devices

PubMed Central

Lu, Junfeng; Shi, Zengliang; Wang, Yueyue; Lin, Yi; Zhu, Qiuxiang; Tian, Zhengshan; Dai, Jun; Wang, Shufeng; Xu, Chunxiang

2016-01-01

Effective and bright light-emitting-diodes (LEDs) have attracted broad interests in fundamental research and industrial application, especially on short wavelength LEDs. In this paper, a well aligned ZnO nanorod arrays grown on the p-GaN substrate to form a heterostructured light-emitting diode and Al nanoparticles (NPs) were decorated to improve the electroluminescence performance. More than 30-folds enhancement of the electroluminescence intensity was obtained compared with the device without Al NPs decoration. The investigation on the stable and transient photoluminescence spectraof the ZnO nanorod arrays before and after Al NPs decoration demonstrated that the metal surface plasmon resonance coupling with excitons of ZnO leads to the enhancement of the internal quantum efficiency (IQE). Our results provide aneffective approach to design novel optoelectronic devices such as light-emitting diodes and plasmonic nanolasers. PMID:27181337

Two-color light-emitting diodes with polarization-sensitive high extraction efficiency based on graphene

NASA Astrophysics Data System (ADS)

H, Sattarian; S, Shojaei; E, Darabi

2016-05-01

In the present study, graphene photonic crystals are employed to enhance the light extraction efficiency (LEE) of two-color, red and blue, light-emitting diode (LED). The transmission characteristics of one-dimensional (1D) Fibonacci graphene photonic crystal LED (FGPC-LED) are investigated by using the transfer matrix method and the scaling study is presented. We analyzed the influence of period, thickness, and permittivity in the structure to enhance the LEE. The transmission spectrum of 1D FGPC has been optimized in detail. In addition, the effects of the angle of incidence and the state of polarization are investigated. As the main result, we found the optimum values of relevant parameters to enhance the extraction of red and blue light from an LED as well as provide perfect omnidirectional and high peak transmission filters for the TE and TM modes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer, Tim; Institut für Physikalische Chemie, Universität zu Köln, 50939 Köln; Schwab, Tobias

A random scattering approach to enhance light extraction in white top-emitting organic light-emitting diodes (OLEDs) is reported. Through solution processing from fluorinated solvents, a nano-particle scattering layer (NPSL) can be deposited directly on top of small molecule OLEDs without affecting their electrical performance. The scattering length for light inside the NPSL is determined from transmission measurements and found to be in agreement with Mie scattering theory. Furthermore, the dependence of the light outcoupling enhancement on electron transport layer thickness is studied. Depending on the electron transport layer thickness, the NPSL enhances the external quantum efficiency of the investigated white OLEDsmore » by between 1.5 and 2.3-fold. For a device structure that has been optimized prior to application of the NPSL, the maximum external quantum efficiency is improved from 4.7% to 7.4% (1.6-fold improvement). In addition, the scattering layer strongly reduces the undesired shift in emission color with viewing angle.« less

Enhanced photoelectrochemical and photocatalytic activity in visible-light-driven Ag/BiVO{sub 4} inverse opals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Liang, E-mail: lfang@suda.edu.cn, E-mail: dawei.cao@tu-ilmenau.de; Nan, Feng; Yang, Ying

2016-02-29

BiVO{sub 4} photonic crystal inverse opals (io-BiVO{sub 4}) with highly dispersed Ag nanoparticles (NPs) were prepared by the nanosphere lithography method combining the pulsed current deposition method. The incorporation of the Ag NPs can significantly improve the photoelectrochemical and photocatalytic activity of BiVO{sub 4} inverse opals in the visible light region. The photocurrent density of the Ag/io-BiVO{sub 4} sample is 4.7 times higher than that of the disordered sample without the Ag NPs, while the enhancement factor of the corresponding kinetic constant in photocatalytic experiment is approximately 3. The improved photoelectrochemical and photocatalytic activity is benefited from two reasons: onemore » is the enhanced light harvesting owing to the coupling between the slow light and localized surface plasmon resonance effect; the other is the efficient separation of charge carriers due to the Schottky barriers.« less

Plasmon-enhanced Electrically Light-emitting from ZnO Nanorod Arrays/p-GaN Heterostructure Devices.

PubMed

Lu, Junfeng; Shi, Zengliang; Wang, Yueyue; Lin, Yi; Zhu, Qiuxiang; Tian, Zhengshan; Dai, Jun; Wang, Shufeng; Xu, Chunxiang

2016-05-16

Effective and bright light-emitting-diodes (LEDs) have attracted broad interests in fundamental research and industrial application, especially on short wavelength LEDs. In this paper, a well aligned ZnO nanorod arrays grown on the p-GaN substrate to form a heterostructured light-emitting diode and Al nanoparticles (NPs) were decorated to improve the electroluminescence performance. More than 30-folds enhancement of the electroluminescence intensity was obtained compared with the device without Al NPs decoration. The investigation on the stable and transient photoluminescence spectraof the ZnO nanorod arrays before and after Al NPs decoration demonstrated that the metal surface plasmon resonance coupling with excitons of ZnO leads to the enhancement of the internal quantum efficiency (IQE). Our results provide aneffective approach to design novel optoelectronic devices such as light-emitting diodes and plasmonic nanolasers.

Inverse Stellation of CuAu-ZnO Multimetallic-Semiconductor Nanostartube for Plasmon-Enhanced Photocatalysis.

PubMed

Tan, Chuan Fu; Su Su Zin, Aung Kyi; Chen, Zhihui; Liow, Chi Hao; Phan, Huy Thong; Tan, Hui Ru; Xu, Qing-Hua; Ho, Ghim Wei

2018-05-22

One-dimensional (1D) metallic nanocrystals constitute an important class of plasmonic materials for localization of light into subwavelength dimensions. Coupled with their intrinsic conductive properties and extended optical paths for light absorption, metallic nanowires are prevalent in light-harnessing applications. However, the transverse surface plasmon resonance (SPR) mode of traditional multiply twinned nanowires often suffers from weaker electric field enhancement due to its low degree of morphological curvature in comparison to other complex anisotropic nanocrystals. Herein, simultaneous anisotropic stellation and excavation of multiply twinned nanowires are demonstrated through a site-selective galvanic reaction for a pronounced manipulation of light-matter interaction. The introduction of longitudinal extrusions and cavitation along the nanowires leads to a significant enhancement in plasmon field with reduced quenching of localized surface plasmon resonance (LSPR). The as-synthesized multimetallic nanostartubes serve as a panchromatic plasmonic framework for incorporation of photocatalytic materials for plasmon-assisted solar fuel production.

Conformal fabrication of colloidal quantum dot solids for optically enhanced photovoltaics.

PubMed

Labelle, André J; Thon, Susanna M; Kim, Jin Young; Lan, Xinzheng; Zhitomirsky, David; Kemp, Kyle W; Sargent, Edward H

2015-05-26

Colloidal quantum dots (CQD) are an attractive thin-film material for photovoltaic applications due to low material costs, ease of fabrication, and size-tunable band gap. Unfortunately, today they suffer from a compromise between light absorption and photocarrier extraction, a fact that currently prevents the complete harvest of incoming above-band-gap solar photons. We have investigated the use of structured substrates and/or electrodes to increase the effective light path through the active material and found that these designs require highly conformal application of the light-absorbing films to achieve the greatest enhancement. This conformality requirement derives from the need for maximal absorption enhancement combined with shortest-distance charge transport. Here we report on a means of processing highly conformal layer-by-layer deposited CQD absorber films onto microstructured, light-recycling electrodes. Specifically, we engineer surface hydrophilicity to achieve conformal deposition of upper layers atop underlying ones. We show that only with the application of conformal coating can we achieve optimal quantum efficiency and enhanced power conversion efficiency in structured-electrode CQD cells.

Look Sharp While Seeing Sharp

NASA Technical Reports Server (NTRS)

2006-01-01

The two scientists James B. Stephens and Dr. Charles G. Miller were tasked with studying the harmful properties of light in space, as well as the artificial radiation produced during laser and welding work, for the purpose of creating an enhanced means of eye protection in industrial welding applications. While working to apply their space research to these terrestrial applications, Stephens and Miller became engrossed with previously discovered research showing evidence that the eyes of hawks, eagles, and other birds of prey contain unique oil droplets that actually protect them from intensely radiated light rays (blue, violet, ultraviolet) while allowing vision-enhancing light rays (red, orange, green) to pass through. These oil droplets absorb short wavelength light rays which, in turn, reduce glare and provide heightened color contrast and definition for optimal visual acuity. Accordingly, birds of prey possess the ability to distinguish their targeted prey in natural surroundings and from great distances. Pairing the findings from their initial studies with what they learned from the bird studies, the scientists devised a methodology to incorporate the light-filtering/vision-enhancing dual-action benefits into a filtering system, using light-filtering dyes and tiny particles of zinc oxide. (Zinc oxide, which absorbs ultraviolet light, is also found in sunscreen lotions that protect the skin from sunburn.)

Tailoring light-matter coupling in semiconductor and hybrid-plasmonic nanowires

PubMed Central

Piccione, Brian; Aspetti, Carlos O.; Cho, Chang-Hee; Agarwal, Ritesh

2014-01-01

Understanding interactions between light and matter is central to many fields, providing invaluable insights into the nature of matter. In its own right, a greater understanding of light-matter coupling has allowed for the creation of tailored applications, resulting in a variety of devices such as lasers, switches, sensors, modulators, and detectors. Reduction of optical mode volume is crucial to enhancing light-matter coupling strength, and among solid-state systems, self-assembled semiconductor and hybrid-plasmonic nanowires are amenable to creation of highly-confined optical modes. Following development of unique spectroscopic techniques designed for the nanowire morphology, carefully engineered semiconductor nanowire cavities have recently been tailored to enhance light-matter coupling strength in a manner previously seen in optical microcavities. Much smaller mode volumes in tailored hybrid-plasmonic nanowires have recently allowed for similar breakthroughs, resulting in sub-picosecond excited-state lifetimes and exceptionally high radiative rate enhancement. Here, we review literature on light-matter interactions in semiconductor and hybrid-plasmonic monolithic nanowire optical cavities to highlight recent progress made in tailoring light-matter coupling strengths. Beginning with a discussion of relevant concepts from optical physics, we will discuss how our knowledge of light-matter coupling has evolved with our ability to produce ever-shrinking optical mode volumes, shifting focus from bulk materials to optical microcavities, before moving on to recent results obtained from semiconducting nanowires. PMID:25093385

Enhanced Photocatalytic Activity of La3+-Doped TiO2 Nanotubes with Full Wave-Band Absorption

NASA Astrophysics Data System (ADS)

Xia, Minghao; Huang, Lingling; Zhang, Yubo; Wang, Yongqian

2018-06-01

TiO2 nanotubes doped with La3+ were synthesized by anodic oxidation method and the photocatalytic activity was detected by photodegrading methylene blue. As-prepared samples improved the absorption of both ultraviolet light and visible light and have a great enhancement on the photocatalytic activity while contrasting with the pristine TiO2 nanotubes. A tentative mechanism for the enhancement of photocatalytic activity with full wave-band absorption is proposed.

Thermodynamic limit to photonic-plasmonic light-trapping in thin films on metals

NASA Astrophysics Data System (ADS)

Schiff, E. A.

2011-11-01

We calculate the maximum optical absorptance enhancements in thin semiconductor films on metals due to structures that diffuse light and couple it to surface plasmon polaritons. The calculations can be used to estimate plasmonic effects on light-trapping in solar cells. The calculations are based on the statistical distribution of energy in the electromagnetic modes of the structure, which include surface plasmon polariton modes at the metal interface as well as the trapped waveguide modes in the film. The enhancement has the form 4n2+nλ/h (n - film refractive index, λ - optical wavelength, h - film thickness), which is an increase beyond the non-plasmonic "classical" enhancement 4n2. Larger resonant enhancements occur for wavelengths near the surface plasmon frequency; these add up to 2 mA/cm2 to the photocurrent of a solar cell based on a 500 nm film of crystalline silicon. We also calculated the effects of plasmon dissipation in the metal. Dissipation rates typical of silver reverse the resonant enhancement effect for silicon, but a non-resonant enhancement remains.

Effect of NASA light-emitting diode irradiation on molecular changes for wound healing in diabetic mice.

PubMed

Whelan, Harry T; Buchmann, Ellen V; Dhokalia, Apsara; Kane, Mary P; Whelan, Noel T; Wong-Riley, Margaret T T; Eells, Janis T; Gould, Lisa J; Hammamieh, Rasha; Das, Rina; Jett, Marti

2003-04-01

The purpose of this study was to assess the changes in gene expression of near-infrared light therapy in a model of impaired wound healing. Light-Emitting Diodes (LED), originally developed for NASA plant growth experiments in space, show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper we present the effects of LED treatment on wounds in a genetically diabetic mouse model. Polyvinyl acetal (PVA) sponges were subcutaneously implanted in the dorsum of BKS.Cg-m +/+ Lepr(db) mice. LED treatments were given once daily, and at the sacrifice day, the sponges, incision line and skin over the sponges were harvested and used for RNA extraction. The RNA was subsequently analyzed by cDNA array. Our studies have revealed certain tissue regenerating genes that were significantly upregulated upon LED treatment when compared to the untreated sample. Integrins, laminin, gap junction proteins, and kinesin superfamily motor proteins are some of the genes involved during regeneration process. These are some of the genes that were identified upon gene array experiments with RNA isolated from sponges from the wound site in mouse with LED treatment. We believe that the use of NASA light-emitting diodes (LED) for light therapy will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the Defense Advanced Research Projects Agency (DARPA) and NASA Marshall Space Flight Center-SBIR Program.

Nonreciprocal plasmonics enables giant enhancement of thin-film Faraday rotation.

PubMed

Chin, Jessie Yao; Steinle, Tobias; Wehlus, Thomas; Dregely, Daniel; Weiss, Thomas; Belotelov, Vladimir I; Stritzker, Bernd; Giessen, Harald

2013-01-01

Light propagation is usually reciprocal. However, a static magnetic field along the propagation direction can break the time-reversal symmetry in the presence of magneto-optical materials. The Faraday effect in magneto-optical materials rotates the polarization plane of light, and when light travels backward the polarization is further rotated. This is applied in optical isolators, which are of crucial importance in optical systems. Faraday isolators are typically bulky due to the weak Faraday effect of available magneto-optical materials. The growing research endeavour in integrated optics demands thin-film Faraday rotators and enhancement of the Faraday effect. Here, we report significant enhancement of Faraday rotation by hybridizing plasmonics with magneto-optics. By fabricating plasmonic nanostructures on laser-deposited magneto-optical thin films, Faraday rotation is enhanced by one order of magnitude in our experiment, while high transparency is maintained. We elucidate the enhanced Faraday effect by the interplay between plasmons and different photonic waveguide modes in our system.

Light-triggered liposomal cargo delivery platform incorporating photosensitizers and gold nanoparticles for enhanced singlet oxygen generation and increased cytotoxicity.

PubMed

Kautzka, Zofia; Clement, Sandhya; Goldys, Ewa M; Deng, Wei

2017-01-01

We developed light-triggered liposomes incorporating 3-5 nm hydrophobic gold nanoparticles and Rose Bengal (RB), a well-known photosensitizer used for photodynamic therapy. Singlet oxygen generated by these liposomes with 532 nm light illumination was characterized for varying the molar ratio of lipids and gold nanoparticles while keeping the amount of RB constant. Gold nanoparticles were found to enhance the singlet oxygen generation rate, with a maximum enhancement factor of 1.75 obtained for the molar ratio of hydrogenated soy l-α-phosphatidylcholine:1,2-dioleoyl- sn -glycero-3-phosphoethanolamine- N -(hexanoylamine):gold of 57:5:17 compared with liposomes loaded with RB alone. The experimental results could be explained by the local electric field enhancement caused by gold nanoparticles. We further assessed cellular cytotoxicity of gold-loaded liposomes by encapsulating an antitumor drug, doxorubicin (Dox); such Dox-loaded liposomes were applied to human colorectal cancer cells (HCT116) and exposed to light. Gold-loaded liposomes containing RB and Dox where Dox release was triggered by light were found to exhibit higher cytotoxicity compared with the liposomes loaded with RB and Dox alone. Our results indicate that gold-loaded liposomes incorporating photosensitizers may serve as improved agents in photodynamic therapy and chemotherapy.

Axl acts as a tumor suppressor by regulating LIGHT expression in T lymphoma

PubMed Central

Young, Kon-Ji; Park, A-Reum; Choi, Ha-Rim; Lee, Hwa-Youn; Kim, Su-Man; Chung, Byung Yeoup; Park, Chul-Hong; Choi, Hyo Jin; Ko, Young-Hyeh; Bai, Hyoung-Woo; Kang, Hyung-Sik

2017-01-01

Axl is an oncogenic receptor tyrosine kinase that plays a role in many cancers. LIGHT (Lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpesvirus entry mediator on T cells) is a ligand that induces robust anti-tumor immunity by enhancing the recruitment and activation of effector immune cells at tumor sites. We observed that mouse EL4 and human Jurkat T lymphoma cells that stably overexpressed Axl also showed high expression of LIGHT. When Jurkat-Axl cells were treated with Gas6, a ligand for Axl, LIGHT expression was upregulated through activation of the PI3K/AKT signaling pathway and transcriptional induction by Sp1. The lytic activity of cytotoxic T lymphocytes and natural killer cells was enhanced by EL4-Axl cells. In addition, tumor volume and growth were markedly reduced due to enhanced apoptotic cell death in EL4-Axl tumor-bearing mice as compared to control mice. We also observed upregulated expression of CCL5 and its receptor, CCR5, and enhanced intratumoral infiltration of cytotoxic T lymphocytes and natural killer cells in EL4-Axl-bearing mice as compared to mock controls. These data strongly suggested that Axl exerts novel tumor suppressor effects by inducing upregulation of LIGHT in the tumor microenvironment of T lymphoma. PMID:28423548

Axl acts as a tumor suppressor by regulating LIGHT expression in T lymphoma.

PubMed

Lee, Eun-Hee; Kim, Eun-Mi; Ji, Kon-Young; Park, A-Reum; Choi, Ha-Rim; Lee, Hwa-Youn; Kim, Su-Man; Chung, Byung Yeoup; Park, Chul-Hong; Choi, Hyo Jin; Ko, Young-Hyeh; Bai, Hyoung-Woo; Kang, Hyung-Sik

2017-03-28

Axl is an oncogenic receptor tyrosine kinase that plays a role in many cancers. LIGHT (Lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpesvirus entry mediator on T cells) is a ligand that induces robust anti-tumor immunity by enhancing the recruitment and activation of effector immune cells at tumor sites. We observed that mouse EL4 and human Jurkat T lymphoma cells that stably overexpressed Axl also showed high expression of LIGHT. When Jurkat-Axl cells were treated with Gas6, a ligand for Axl, LIGHT expression was upregulated through activation of the PI3K/AKT signaling pathway and transcriptional induction by Sp1. The lytic activity of cytotoxic T lymphocytes and natural killer cells was enhanced by EL4-Axl cells. In addition, tumor volume and growth were markedly reduced due to enhanced apoptotic cell death in EL4-Axl tumor-bearing mice as compared to control mice. We also observed upregulated expression of CCL5 and its receptor, CCR5, and enhanced intratumoral infiltration of cytotoxic T lymphocytes and natural killer cells in EL4-Axl-bearing mice as compared to mock controls. These data strongly suggested that Axl exerts novel tumor suppressor effects by inducing upregulation of LIGHT in the tumor microenvironment of T lymphoma.

Light-triggered liposomal cargo delivery platform incorporating photosensitizers and gold nanoparticles for enhanced singlet oxygen generation and increased cytotoxicity

PubMed Central

Kautzka, Zofia; Clement, Sandhya; Goldys, Ewa M; Deng, Wei

2017-01-01

We developed light-triggered liposomes incorporating 3–5 nm hydrophobic gold nanoparticles and Rose Bengal (RB), a well-known photosensitizer used for photodynamic therapy. Singlet oxygen generated by these liposomes with 532 nm light illumination was characterized for varying the molar ratio of lipids and gold nanoparticles while keeping the amount of RB constant. Gold nanoparticles were found to enhance the singlet oxygen generation rate, with a maximum enhancement factor of 1.75 obtained for the molar ratio of hydrogenated soy l-α-phosphatidylcholine:1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(hexanoylamine):gold of 57:5:17 compared with liposomes loaded with RB alone. The experimental results could be explained by the local electric field enhancement caused by gold nanoparticles. We further assessed cellular cytotoxicity of gold-loaded liposomes by encapsulating an antitumor drug, doxorubicin (Dox); such Dox-loaded liposomes were applied to human colorectal cancer cells (HCT116) and exposed to light. Gold-loaded liposomes containing RB and Dox where Dox release was triggered by light were found to exhibit higher cytotoxicity compared with the liposomes loaded with RB and Dox alone. Our results indicate that gold-loaded liposomes incorporating photosensitizers may serve as improved agents in photodynamic therapy and chemotherapy. PMID:28203076

Light-quality and temperature-dependent CBF14 gene expression modulates freezing tolerance in cereals.

PubMed

Novák, Aliz; Boldizsár, Ákos; Ádám, Éva; Kozma-Bognár, László; Majláth, Imre; Båga, Monica; Tóth, Balázs; Chibbar, Ravindra; Galiba, Gábor

2016-03-01

C-repeat binding factor 14 (CBF14) is a plant transcription factor that regulates a set of cold-induced genes, contributing to enhanced frost tolerance during cold acclimation. Many CBF genes are induced by cool temperatures and regulated by day length and light quality, which affect the amount of accumulated freezing tolerance. Here we show that a low red to far-red ratio in white light enhances CBF14 expression and increases frost tolerance at 15°C in winter Triticum aesitivum and Hordeum vulgare genotypes, but not in T. monococcum (einkorn), which has a relatively low freezing tolerance. Low red to far-red ratio enhances the expression of PHYA in all three species, but induces PHYB expression only in einkorn. Based on our results, a model is proposed to illustrate the supposed positive effect of phytochrome A and the negative influence of phytochrome B on the enhancement of freezing tolerance in cereals in response to spectral changes of incident light. CBF-regulon, barley, cereals, cold acclimation, freezing tolerance, light regulation, low red/far-red ratio, phytochrome, wheat. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

GaN-on-Si blue/white LEDs: epitaxy, chip, and package

NASA Astrophysics Data System (ADS)

Qian, Sun; Wei, Yan; Meixin, Feng; Zengcheng, Li; Bo, Feng; Hanmin, Zhao; Hui, Yang

2016-04-01

The dream of epitaxially integrating III-nitride semiconductors on large diameter silicon is being fulfilled through the joint R&D efforts of academia and industry, which is driven by the great potential of GaN-on-silicon technology in improving the efficiency yet at a much reduced manufacturing cost for solid state lighting and power electronics. It is very challenging to grow high quality GaN on Si substrates because of the huge mismatch in the coefficient of thermal expansion (CTE) and the large mismatch in lattice constant between GaN and silicon, often causing a micro-crack network and a high density of threading dislocations (TDs) in the GaN film. Al-composition graded AlGaN/AlN buffer layers have been utilized to not only build up a compressive strain during the high temperature growth for compensating the tensile stress generated during the cool down, but also filter out the TDs to achieve crack-free high-quality n-GaN film on Si substrates, with an X-ray rocking curve linewidth below 300 arcsec for both (0002) and (101¯2) diffractions. Upon the GaN-on-Si templates, prior to the deposition of p-AlGaN and p-GaN layers, high quality InGaN/GaN multiple quantum wells (MQWs) are overgrown with well-engineered V-defects intentionally incorporated to shield the TDs as non-radiative recombination centers and to enhance the hole injection into the MQWs through the via-like structures. The as-grown GaN-on-Si LED wafers are processed into vertical structure thin film LED chips with a reflective p-electrode and the N-face surface roughened after the removal of the epitaxial Si(111) substrates, to enhance the light extraction efficiency. We have commercialized GaN-on-Si LEDs with an average efficacy of 150-160 lm/W for 1mm2 LED chips at an injection current of 350 mA, which have passed the 10000-h LM80 reliability test. The as-produced GaN-on-Si LEDs featured with a single-side uniform emission and a nearly Lambertian distribution can adopt the wafer-level phosphor coating procedure, and are suitable for directional lighting, camera flash, streetlighting, automotive headlamps, and otherlighting applications. Project supported financially by the National Natural Science Foundation of China (Nos. 61522407, 61534007, 61404156), the National High Technology Research and Development Program of China (No. 2015AA03A102), the Science & Technology Program of Jiangsu Province (Nos. BA2015099, BE2012063), the Suzhou Science & Technology Program (No. ZXG2013042), and the Recruitment Program of Global Experts (1000 Youth Talents Plan). Project also supported technically by Nano-X from SINANO, CAS

Measurement and Validation of Bidirectional Reflectance of Space Shuttle and Space Station Materials for Computerized Lighting Models

NASA Technical Reports Server (NTRS)

Fletcher, Lauren E.; Aldridge, Ann M.; Wheelwright, Charles; Maida, James

1997-01-01

Task illumination has a major impact on human performance: What a person can perceive in his environment significantly affects his ability to perform tasks, especially in space's harsh environment. Training for lighting conditions in space has long depended on physical models and simulations to emulate the effect of lighting, but such tests are expensive and time-consuming. To evaluate lighting conditions not easily simulated on Earth, personnel at NASA Johnson Space Center's (JSC) Graphics Research and Analysis Facility (GRAF) have been developing computerized simulations of various illumination conditions using the ray-tracing program, Radiance, developed by Greg Ward at Lawrence Berkeley Laboratory. Because these computer simulations are only as accurate as the data used, accurate information about the reflectance properties of materials and light distributions is needed. JSC's Lighting Environment Test Facility (LETF) personnel gathered material reflectance properties for a large number of paints, metals, and cloths used in the Space Shuttle and Space Station programs, and processed these data into reflectance parameters needed for the computer simulations. They also gathered lamp distribution data for most of the light sources used, and validated the ability to accurately simulate lighting levels by comparing predictions with measurements for several ground-based tests. The result of this study is a database of material reflectance properties for a wide variety of materials, and lighting information for most of the standard light sources used in the Shuttle/Station programs. The combination of the Radiance program and GRAF's graphics capability form a validated computerized lighting simulation capability for NASA.

Fungal Gene Mutation Analysis Elucidating Photoselective Enhancement of UV-C Disinfection Efficiency Toward Spoilage Agents on Fruit Surface.

PubMed

Zhu, Pinkuan; Li, Qianwen; Azad, Sepideh M; Qi, Yu; Wang, Yiwen; Jiang, Yina; Xu, Ling

2018-01-01

Short-wave ultraviolet (UV-C) treatment represents a potent, clean and safe substitute to chemical sanitizers for fresh fruit preservation. However, the dosage requirement for microbial disinfection may have negative effects on fruit quality. In this study, UV-C was found to be more efficient in killing spores of Botrytis cinerea in dark and red light conditions when compared to white and blue light. Loss of the blue light receptor gene Bcwcl1 , a homolog of wc-1 in Neurospora crassa , led to hypersensitivity to UV-C in all light conditions tested. The expression of Bcuve1 and Bcphr1 , which encode UV-damage endonuclease and photolyase, respectively, were strongly induced by white and blue light in a Bcwcl1 -dependent manner. Gene mutation analyses of Bcuve1 and Bcphr1 indicated that they synergistically contribute to survival after UV-C treatment. In vivo assays showed that UV-C (1.0 kJ/m 2 ) abolished decay in drop-inoculated fruit only if the UV-C treatment was followed by a dark period or red light, while in contrast, typical decay appeared on UV-C irradiated fruits exposed to white or blue light. In summary, blue light enhances UV-C resistance in B. cinerea by inducing expression of the UV damage repair-related enzymes, while the efficiency of UV-C application for fruit surface disinfection can be enhanced in dark or red light conditions; these principles seem to be well conserved among postharvest fungal pathogens.

PINOID AGC kinases are necessary for phytochrome-mediated enhancement of hypocotyl phototropism in Arabidopsis.

PubMed

Haga, Ken; Hayashi, Ken-ichiro; Sakai, Tatsuya

2014-11-01

Several members of the AGCVIII kinase subfamily, which includes PINOID (PID), PID2, and WAVY ROOT GROWTH (WAG) proteins, have previously been shown to phosphorylate PIN-FORMED (PIN) auxin transporters and control the auxin flow in plants. PID has been proposed as a key component of the phototropin signaling pathway that induces phototropic responses, although the responses were not significantly impaired in the pid single and pid wag1 wag2 triple mutants. This raises questions about the functional roles of the PID family in phototropic responses. Here, we investigated hypocotyl phototropism in the pid pid2 wag1 wag2 quadruple mutant in detail to clarify the roles of the PID family in Arabidopsis (Arabidopsis thaliana). The pid quadruple mutants exhibited moderate responses in continuous light-induced phototropism with a decrease in growth rates of hypocotyls and normal responses in pulse-induced phototropism. However, they showed serious defects in enhancements of pulse-induced phototropic curvatures and lateral fluorescent auxin transport by red light pretreatment. Red light pretreatment significantly reduced the expression level of PID, and the constitutive expression of PID prevented pulse-induced phototropism, irrespective of red light pretreatment. This suggests that the PID family plays a significant role in phytochrome-mediated phototropic enhancement but not the phototropin signaling pathway. Red light treatment enhanced the intracellular accumulation of PIN proteins in response to the vesicle-trafficking inhibitor brefeldin A in addition to increasing their expression levels. Taken together, these results suggest that red light preirradiation enhances phototropic curvatures by up-regulation of PIN proteins, which are not being phosphorylated by the PID family. © 2014 American Society of Plant Biologists. All Rights Reserved.

PINOID AGC Kinases Are Necessary for Phytochrome-Mediated Enhancement of Hypocotyl Phototropism in Arabidopsis1[W][OPEN

PubMed Central

Haga, Ken; Hayashi, Ken-ichiro; Sakai, Tatsuya

2014-01-01

Several members of the AGCVIII kinase subfamily, which includes PINOID (PID), PID2, and WAVY ROOT GROWTH (WAG) proteins, have previously been shown to phosphorylate PIN-FORMED (PIN) auxin transporters and control the auxin flow in plants. PID has been proposed as a key component of the phototropin signaling pathway that induces phototropic responses, although the responses were not significantly impaired in the pid single and pid wag1 wag2 triple mutants. This raises questions about the functional roles of the PID family in phototropic responses. Here, we investigated hypocotyl phototropism in the pid pid2 wag1 wag2 quadruple mutant in detail to clarify the roles of the PID family in Arabidopsis (Arabidopsis thaliana). The pid quadruple mutants exhibited moderate responses in continuous light-induced phototropism with a decrease in growth rates of hypocotyls and normal responses in pulse-induced phototropism. However, they showed serious defects in enhancements of pulse-induced phototropic curvatures and lateral fluorescent auxin transport by red light pretreatment. Red light pretreatment significantly reduced the expression level of PID, and the constitutive expression of PID prevented pulse-induced phototropism, irrespective of red light pretreatment. This suggests that the PID family plays a significant role in phytochrome-mediated phototropic enhancement but not the phototropin signaling pathway. Red light treatment enhanced the intracellular accumulation of PIN proteins in response to the vesicle-trafficking inhibitor brefeldin A in addition to increasing their expression levels. Taken together, these results suggest that red light preirradiation enhances phototropic curvatures by up-regulation of PIN proteins, which are not being phosphorylated by the PID family. PMID:25281709

Design and testing of a dual-band enhanced vision system

NASA Astrophysics Data System (ADS)

Way, Scott P.; Kerr, Richard; Imamura, Joseph J.; Arnoldy, Dan; Zeylmaker, Dick; Zuro, Greg

2003-09-01

An effective enhanced vision system must operate over a broad spectral range in order to offer a pilot an optimized scene that includes runway background as well as airport lighting and aircraft operations. The large dynamic range of intensities of these images is best handled with separate imaging sensors. The EVS 2000 is a patented dual-band Infrared Enhanced Vision System (EVS) utilizing image fusion concepts. It has the ability to provide a single image from uncooled infrared imagers combined with SWIR, NIR or LLLTV sensors. The system is designed to provide commercial and corporate airline pilots with improved situational awareness at night and in degraded weather conditions but can also be used in a variety of applications where the fusion of dual band or multiband imagery is required. A prototype of this system was recently fabricated and flown on the Boeing Advanced Technology Demonstrator 737-900 aircraft. This paper will discuss the current EVS 2000 concept, show results taken from the Boeing Advanced Technology Demonstrator program, and discuss future plans for the fusion system.

Getting Pool Light Right.

ERIC Educational Resources Information Center

Hunsaker, Scot

1998-01-01

Examines the use of lighting, both artificial and natural, that can enhance the aesthetic quality and functionality of areas with indoor swimming pools. Discusses glare and shadow-reduction measures that aid competitive events, including lighting above and below water levels, and highlights lighting issues during televised events. Descriptions of…

Evaluating the Field Emission Characteristics of Aluminum for DC High Voltage Photo-Electron Guns

NASA Astrophysics Data System (ADS)

Taus, Rhys; Poelker, Matthew; Forman, Eric; Mamun, Abdullah

2014-03-01

High current photoguns require high power laser light, but only a small portion of the laser light illuminating the photocathode produces electron beam. Most of the laser light (~ 65%) simply serves to heat the photocathode, which leads to evaporation of the chemicals required to create the negative electron affinity condition necessary for photoemission. Photocathode cooling techniques have been employed to address this problem, but active cooling of the photocathode is complicated because the cooling apparatus must float at high voltage. This work evaluates the field emission characteristics of cathode electrodes manufactured from materials with high thermal conductivity: aluminum and copper. These electrodes could serve as effective heat sinks, to passively cool the photocathode that resides within such a structure. However, literature suggests ``soft'' materials like aluminum and copper are ill suited for photogun applications, due to excessive field emission when biased at high voltage. This work provides an evaluation of aluminum and copper electrodes inside a high voltage field emission test stand, before and after coating with titanium nitride (TiN), a coating that enhances surface hardness. National Science Foundation Award Number: 1062320 and the Department of Defence ASSURE program.

Light- and singlet oxygen-mediated antifungal activity of phenylphenalenone phytoalexins.

PubMed

Lazzaro, Alejandra; Corominas, Montserrat; Martí, Cristina; Flors, Cristina; Izquierdo, Laura R; Grillo, Teresa A; Luis, Javier G; Nonell, Santi

2004-07-01

The light-induced singlet oxygen production and antifungal activity of phenylphenalenone phytoalexins isolated from infected banana plants (Musa acuminata) are reported. Upon absorption of light energy all studied phenylphenalenones sensitise the production of singlet oxygen in polar and non-polar media. Antifungal activity of these compounds towards Fusarium oxysporum is enhanced in the presence of light. These results, together with the correlation of IC50 values under illumination with the quantum yield of singlet oxygen production and the enhancing effect of D2O on the antifungal activity, suggest the intermediacy of singlet oxygen produced by electronic excitation of the phenylphenalenone phytoalexins.

Light Pollution

ERIC Educational Resources Information Center

Riegel, Kurt W.

1973-01-01

Outdoor lighting is light pollution which handicaps certain astronomical programs. Protective measures must be adopted by the government to aid observational astronomy without sacrificing legitimate outdoor lighting needs. (PS)

Blue light aids in coping with the post-lunch dip: an EEG study.

PubMed

Baek, Hongchae; Min, Byoung-Kyong

2015-01-01

The 'post-lunch dip' is a commonly experienced period of drowsiness in the afternoon hours. If this inevitable period can be disrupted by an environmental cue, the result will be enhanced workplace performance. Because blue light is known to be a critical cue for entraining biological rhythms, we investigated whether blue light illumination can be a practical strategy for coping with the post-lunch dip. Twenty healthy participants underwent a continuous performance test, during which the electroencephalogram (EEG) was recorded under four different illumination conditions: dark ( < 0.3 lx), 33% blue-enriched light, 66% blue-enriched light and white polychromatic light. As a result, exposure to blue-enriched light during the post-lunch dip period significantly reduced the EEG alpha activity, and increased task performance. Since desynchronisation of alpha activity reflects enhancement of vigilance, our findings imply that blue light might disrupt the post-lunch dip. Subsequent exploration of illumination parameters will be beneficial for possible chronobiological and ergonomic applications.

Is BodyThink an efficacious body image and self-esteem program? A controlled evaluation with adolescents.

PubMed

Richardson, Shanel M; Paxton, Susan J; Thomson, Julie S

2009-03-01

This study aimed to evaluate the efficacy of BodyThink, a widely disseminated body image and self-esteem program. Participants were 277, grade 7 students from 4 secondary schools in Australia. The intervention group (62 girls, 85 boys) participated in BodyThink during four 50-min lessons, while the control group (65 girls, 65 boys) received their usual classes. All participants completed baseline, postintervention and 3-month follow-up questionnaires. For girls, the intervention group reported higher media literacy and lower internalization of the thin ideal compared to the control group. For boys, the intervention group reported higher media literacy and body satisfaction than the control group. Although some positive outcomes were observed, it would be valuable to find ways to enhance the impact of BodyThink, especially in light of its wide dissemination. Suggestions for improving BodyThink are presented.

Clinical skill development for community pharmacists.

PubMed

Barnette, D J; Murphy, C M; Carter, B L

1996-09-01

The importance of establishing clinical pharmacy services in the community cannot be understated in light of current challenges to the traditional dispensing role as the primary service of the community pharmacist. Advancements in automated dispensing technology and declining prescription fee reimbursement are rapidly forcing pharmacists to seek alternative sources of revenue. Providing pharmaceutical care is a viable option to increase customer loyalty job satisfaction, and reimbursement. To support the development of clinical services, academic institutions are forming partnerships with individual community practitioners to overcome perceived educational and training barriers. The authors describe the design and development of two unique clinical skill development programs at the University of Illinois at Chicago. This paper also outlines the patient focused services that the participants have established upon completing the training. These programs successfully enhanced participants' therapeutic knowledge base and facilitated development of the clinical skills necessary for direct patient care.

Programmed activation of cancer cell apoptosis: A tumor-targeted phototherapeutic topoisomerase I inhibitor

NASA Astrophysics Data System (ADS)

Shin, Weon Sup; Han, Jiyou; Kumar, Rajesh; Lee, Gyung Gyu; Sessler, Jonathan L.; Kim, Jong-Hoon; Kim, Jong Seung

2016-07-01

We report here a tumor-targeting masked phototherapeutic agent 1 (PT-1). This system contains SN-38—a prodrug of the topoisomerase I inhibitor irinotecan. Topoisomerase I is a vital enzyme that controls DNA topology during replication, transcription, and recombination. An elevated level of topoisomerase I is found in many carcinomas, making it an attractive target for the development of effective anticancer drugs. In addition, PT-1 contains both a photo-triggered moiety (nitrovanillin) and a cancer targeting unit (biotin). Upon light activation in cancer cells, PT-1 interferes with DNA re-ligation, diminishes the expression of topoisomerase I, and enhances the expression of inter alia mitochondrial apoptotic genes, death receptors, and caspase enzymes, inducing DNA damage and eventually leading to apoptosis. In vitro and in vivo studies showed significant inhibition of cancer growth and the hybrid system PT-1 thus shows promise as a programmed photo-therapeutic (“phototheranostic”).

Repetitive elements dynamics in cell identity programming, maintenance and disease.

PubMed

Bodega, Beatrice; Orlando, Valerio

2014-12-01

The days of 'junk DNA' seem to be over. The rapid progress of genomics technologies has been unveiling unexpected mechanisms by which repetitive DNA and in particular transposable elements (TEs) have evolved, becoming key issues in understanding genome structure and function. Indeed, rather than 'parasites', recent findings strongly suggest that TEs may have a positive function by contributing to tissue specific transcriptional programs, in particular as enhancer-like elements and/or modules for regulation of higher order chromatin structure. Further, it appears that during development and aging genomes experience several waves of TEs activation, and this contributes to individual genome shaping during lifetime. Interestingly, TEs activity is major target of epigenomic regulation. These findings are shedding new light on the genome-phenotype relationship and set the premises to help to explain complex disease manifestation, as consequence of TEs activity deregulation. Copyright © 2014. Published by Elsevier Ltd.

NASA-UVa light aerospace alloy and structures technology program

NASA Technical Reports Server (NTRS)

Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Scully, John R.; Stoner, Glenn E.; Swanson, Robert E.; Thornton, Earl A.; Wawner, Franklin E., Jr.

1991-01-01

The general objective of the NASA-UVa Light Aerospace Alloy and Structures Technology Program was to conduct research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures. The following research areas were actively investigated: (1) mechanical and environmental degradation mechanisms in advanced light metals and composites; (2) aerospace materials science; (3) mechanics of materials and composites for aerospace structures; and (4) thermal gradient structures.

Light absorption and morphological properties of soot-containing aerosols observed at an East Asian outflow site, Noto Peninsula, Japan

NASA Astrophysics Data System (ADS)

Ueda, Sayako; Nakayama, Tomoki; Taketani, Fumikazu; Adachi, Kouji; Matsuki, Atsushi; Iwamoto, Yoko; Sadanaga, Yasuhiro; Matsumi, Yutaka

2016-03-01

The coating of black carbon (BC) with inorganic salts and organic compounds can enhance the magnitude of light absorption by BC. To elucidate the enhancement of light absorption of aged BC particles and its relation to the mixing state and morphology of individual particles, we conducted observations of particles at an Asian outflow site in Noto Peninsula, Japan, in the spring of 2013. Absorption and scattering coefficients at 405, 532, and 781 nm and mass concentrations/mixing states of refractory BC in PM2.5 were measured using a three-wavelength photoacoustic soot spectrometer and a single-particle soot photometer (SP2), respectively, after passage through a thermodenuder (TD) maintained at 300 or 400 °C or a bypass line maintained at room temperature (25 °C). The average enhancement factor of BC light absorption due to coating was estimated by comparing absorption coefficients at 781 nm for particles that with and without passing through the TD at 300 °C and was found to be 1.22. The largest enhancements (> 1.30) were observed under high absorption coefficient periods when the air mass was long-range transported from urban areas in China. Aerosol samples were also analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. The morphological features and mixing states of soot-containing particles of four samples collected during the high absorption events were analyzed by comparing microphotographs before and after the evaporation of beam-sensitive materials by irradiation with a high-density electron beam. The majority of the soot in all samples was found as mixed particles with sulfate-containing spherules or as clusters of such spherules. For samples showing high enhancement (> 1.30) of BC light absorption, the TEM showed that the internally mixed soot-containing particles tended to have a more spherical shape and to be thickly coated. The SP2 measurements also suggested that the proportion of thickly coated soot was greater. Thus, the observed enhancement of BC light absorption was found to differ according to the mixing states and morphology of soot-containing particles. The enhancement of BC light absorption in our in situ measurements and its relation with individual features of soot-containing particles will be useful to evaluate direct radiative forcing in the downwind areas of large emission sources of BC.

Light absorption and morphological properties of soot-containing aerosols observed at an East Asian outflow site, Noto Peninsula, Japan

NASA Astrophysics Data System (ADS)

Ueda, S.; Nakayama, T.; Taketani, F.; Adachi, K.; Matsuki, A.; Iwamoto, Y.; Sadanaga, Y.; Matsumi, Y.

2015-09-01

The coating of black carbon (BC) with inorganic salts and organic compounds can enhance the magnitude of light absorption by BC. To elucidate the enhancement of light absorption of aged BC particles and its relation to the mixing state and morphology of individual particles, we conducted observations of particles at an Asian outflow site in Noto Peninsula, Japan, in the spring of 2013. Absorption and scattering coefficients at 405, 532, and 781 nm and mass concentrations/mixing states of refractory-BC in PM2.5 were measured using a three-wavelength photoacoustic soot spectrometer and a single-particle soot photometer (SP2), respectively, after passage through a heater maintained at 300 or 400 °C or a bypass line maintained at room temperature (25 °C). The average enhancement of BC light absorption due to coating was estimated by comparing absorption coefficients at 781 nm for particles that with and without passing through the heater and was found to be 22-23 %. The largest enhancements (> 30 %) were observed under high absorption coefficient conditions when the air mass was long-range transported from urban areas in China. Aerosol samples were also analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. The morphological features and mixing states of soot-containing particles of four samples collected during the high absorption coefficient events were analyzed by comparing microphotographs before and after the evaporation of beam-sensitive materials by irradiation with a high density electron beam. The majority of the soot in all samples was found as mixed particles with spherical sulfate or as clusters of sulfate spherules. For samples showing high enhancement (> 30 %) of BC light absorption, TEM showed that the internally mixed soot-containing particles tended to have a more spherical shape and to be embedded into the sulfate. The SP2 measurements also suggested that the proportion of thickly-coated soot was greater. Thus, the observed enhancement of BC light absorption was found to differ according to the mixing states and morphology of soot-containing particles. The enhancement of BC light absorption in our in situ measurements and its relation with individual features of soot-containing particles will be useful to evaluate direct radiative forcing in the leeward areas of large emission sources of BC.

Enhancing the sensitivity of slow light MZI biosensors through multi-hole defects

NASA Astrophysics Data System (ADS)

Qin, Kun; Zhao, Yiliang; Hu, Shuren; Weiss, Sharon M.

2018-02-01

We demonstrate enhanced detection sensitivity of a slow light Mach-Zehnder interferometer (MZI) sensor by incorporating multi-hole defects (MHDs). Slow light MZI biosensors with a one-dimensional photonic crystal in one arm have been previously shown to improve the performance of traditional MZI sensors based on the increased lightmatter interaction that takes place in the photonic crystal region of the structure. Introducing MHDs in the photonic crystal region increases the available surface area for molecular attachment and further increases the enhanced lightmatter interaction capability of slow light MZIs. The MHDs allow analyte to interact with a greater fraction of the guided wave in the MZI. For a slow light MHD MZI sensor with a 16 μm long sensing arm, a bulk sensitivity of 151,000 rad/RIU-cm is demonstrated experimentally, which is approximately two-fold higher than our previously reported slow light MZI sensors and thirteen-fold higher than traditional MZI biosensors with millimeter length sensing regions. For the label-free detection of nucleic acids, the slow light MZI with MHDs also exhibits a two-fold sensitivity improvement in experiment compared to the slow light MZI without MHDs. Because the detection sensitivity of slow light MHD MZIs scales with the length of the sensing arm, the tradeoff between detection limit and device size can be appropriately mitigated for different applications. All experimental results presented in this work are in good agreement with finite difference-time domain-calculations. Overall, the slow light MZI biosensors with MHDs are a promising platform for highly sensitive and multiplexed lab-on-chip systems.

Sea turtles, light pollution, and citizen science: A preliminary report

USGS Publications Warehouse

Afford, Heather; Teel, Susan; Nicholas, Mark; Stanley, Thomas; White, Jeremy

2017-01-01

such as entanglement in fishing gear and ingestion of marine debris, as well as possible changes in sex ratios due to increasing temperatures related to human-induced global warming. Locally, light pollution from residential, commercial, and industrial neighborhoods from nearby cities impacts the entirety of Gulf Islands, which spans 160 miles along the Gulf Coast, from Florida to Mississippi, and includes critical habitat for threatened and endangered sea turtles. Because light pollution has been hypothesized to negatively impact sea turtle nesting and hatchling survival, Gulf Islands undertook an effort to understand the relationship between light pollution and sea turtles and create unique educational and outreach opportunities by launching a citizen science program called Turtle Teens Helping in the Seashore (Turtle THIS). At the onset, the Turtle THIS program had two primary goals: quantify the association between light pollution and sea turtle nesting and hatching events using rigorous scientific methods; and initiate a citizen science volunteer program to provide youth with hands-on science and environmental stewardship roles, where they also gain employable skills and career opportunities. With multiple scientific hypotheses to consider, the development of a citizen science program became crucial. Such circumstances allowed Turtle THIS to grow a volunteer and intern program, quantify hypothesized light effects on sea turtles through developed methods, and begin to gather preliminary findings.

The need for lighting education

NASA Astrophysics Data System (ADS)

Julian, Warren G.

2002-05-01

It is amazing that in a world now dominated by light - a world that is absolutely dependent upon light - that there is almost no lighting education. In a few countries of the world there exist tertiary level lighting programs but these can be counted on the fingers of two hands. Developments in lighting technology have produced a range of design tools that can lead to improved and energy-efficient lighting. However, most of this technology is 'harder' to use than traditional technology, emphasizing the need for not only improved lighting education but for its initiation. This paper discusses the need for education and uses the example of the University of Sydney program as a possible basis for others to use. It also examines how it is being delivered in Singapore.

76 FR 10024 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-23

... Engine Testing Program (Renewal) AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY... electronic docket, go to http://www.regulations.gov . Title: EPA's In-Use Vehicle and Engine Testing Programs...-use light-duty (passenger car and light truck) motor vehicles. This program operates in conjunction...

Airport Lighting Equipment Certification Program

DOT National Transportation Integrated Search

1995-05-15

This advisory circular (AC) describes the Airport Lighting Equipment : Certification Program (ALECP). It provides information on how an organization : can get Federal Aviation Administration (FAA) acceptance as a third party : certification body and ...

General point dipole theory for periodic metasurfaces: magnetoelectric scattering lattices coupled to planar photonic structures.

PubMed

Chen, Yuntian; Zhang, Yan; Femius Koenderink, A

2017-09-04

We study semi-analytically the light emission and absorption properties of arbitrary stratified photonic structures with embedded two-dimensional magnetoelectric point scattering lattices, as used in recent plasmon-enhanced LEDs and solar cells. By employing dyadic Green's function for the layered structure in combination with the Ewald lattice summation to deal with the particle lattice, we develop an efficient method to study the coupling between planar 2D scattering lattices of plasmonic, or metamaterial point particles, coupled to layered structures. Using the 'array scanning method' we deal with localized sources. Firstly, we apply our method to light emission enhancement of dipole emitters in slab waveguides, mediated by plasmonic lattices. We benchmark the array scanning method against a reciprocity-based approach to find that the calculated radiative rate enhancement in k-space below the light cone shows excellent agreement. Secondly, we apply our method to study absorption-enhancement in thin-film solar cells mediated by periodic Ag nanoparticle arrays. Lastly, we study the emission distribution in k-space of a coupled waveguide-lattice system. In particular, we explore the dark mode excitation on the plasmonic lattice using the so-called array scanning method. Our method could be useful for simulating a broad range of complex nanophotonic structures, i.e., metasurfaces, plasmon-enhanced light emitting systems and photovoltaics.

Tunable plasmon-enhanced broadband light harvesting for perovskite solar cells

NASA Astrophysics Data System (ADS)

Que, Meidan; Zhu, Liangliang; Yang, Yawei; Liu, Jie; Chen, Peng; Chen, Wei; Yin, Xingtian; Que, Wenxiu

2018-04-01

In this work, we report a reliable method for synthesizing (Au, Au/Ag core)/(TiO2 shell) nanostructures with their plasmonic wavelengths covering the visible light region for perovskite solar cells. The mono- and bi-metallic core-shell nanoparticles exhibit tunable localized surface plasmon resonance wavelength and function as "light tentacle" to improve the photo-electricity conversion efficiency. Plasmonic nanoparticles with different sizes and shapes, different thicknesses of TiO2 shell and Ag interlayer are found to have a strong influence on the localized surface plasmon resonance enhancement effect. The experimental photovoltaic performance of perovskite solar cells is significantly enhanced when the plasmonic nanoparticles are embedded inmesoporous TiO2 scaffolds. A champion photo-electricity conversion efficiency of 17.85% is achieved with nanoparticles (Au/Ag, λLSPR = 650 nm), giving a 18.7% enhancement over that of the pristine device (15.04%). Finite-difference time-domain simulations show that nanorod Au in mesoporus TiO2 scaffold induces the most intense electromagnetic coupling, and provides a novel emitter for photon flux in mesoporous perovskite solar cells. These theoretical results are consistent with the corresponding experimental those. Thus, enhancing the incident light intensities around 650 nm will be most favorable to the improvement of the photo-electricity conversion efficiency of perovskite solar cells.

Optoelectrofluidic enhanced immunoreaction based on optically-induced dynamic AC electroosmosis.

PubMed

Han, Dongsik; Park, Je-Kyun

2016-04-07

We report a novel optoelectrofluidic immunoreaction system based on electroosmotic flow for enhancing antibody-analyte binding efficiency on a surface-based sensing system. Two conventional indium tin oxide glass slides are assembled to provide a reaction chamber for a tiny volume of sample droplet (∼5 μL), in which the top layer is employed as an antibody-immobilized substrate and the bottom layer acts as a photoconductive layer of an optoelectrofluidic device. Under the application of an AC voltage, an illuminated light pattern on the photoconductive layer causes strong counter-rotating vortices to transport analytes from the bulk solution to the vicinity of the assay spot on the glass substrate. This configuration overcomes the slow immunoreaction problem of a diffusion-based sensing system, resulting in the enhancement of binding efficiency via an optoelectrofluidic method. Furthermore, we investigate the effect of optically-induced dynamic AC electroosmotic flow on optoelectrofluidic enhancement for surface-based immunoreaction with a mathematical simulation study and real experiments using immunoglobulin G (IgG) and anti-IgG. As a result, dynamic light patterns provided better immunoreaction efficiency than static light patterns due to effective mass transport of the target analyte, resulting in an achievement of 2.18-fold enhancement under a growing circular light pattern compared to the passive mode.

Effects of current crowding on light extraction efficiency of conventional GaN-based light-emitting diodes.

PubMed

Cao, Bin; Li, Shuiming; Hu, Run; Zhou, Shengjun; Sun, Yi; Gan, Zhiying; Liu, Sheng

2013-10-21

Current crowding effects (CCEs) on light extraction efficiency (LEE) of conventional GaN-based light-emitting diodes (LEDs) are analyzed through Monte Carlo ray-tracing simulation. The non-uniform radiative power distribution of the active layer of the Monte Carlo model is obtained based on the current spreading theory and rate equation. The simulation results illustrate that CCE around n-pad (n-CCE) has little effect on LEE, while CCE around p-pad (p-CCE) results in a notable LEE droop due to the significant absorption of photons emitted under p-pad. LEE droop is alleviated by a SiO₂ current blocking layer (CBL) and reflective p-pad. Compared to the conventional LEDs without CBL, the simulated LEE of LEDs with CBL at 20 A/cm² and 70 A/cm² is enhanced by 7.7% and 19.0%, respectively. It is further enhanced by 7.6% and 11.4% after employing a reflective p-pad due to decreased absorption. These enhancements are in accordance with the experimental results. Output power of LEDs with CBL is enhanced by 8.7% and 18.2% at 20 A/cm² and 70 A/cm², respectively. And the reflective p-pad results in a further enhancement of 8.9% and 12.7%.

Highly Ordered Periodic Au/TiO₂ Hetero-Nanostructures for Plasmon-Induced Enhancement of the Activity and Stability for Ethanol Electro-oxidation.

PubMed

Jin, Zhao; Wang, Qiyu; Zheng, Weitao; Cui, Xiaoqiang

2016-03-02

The catalytic electro-oxidation of ethanol is the essential technique for direct alcohol fuel cells (DAFCs) in the area of alternative energy for the ability of converting the chemical energy of alcohol into the electric energy directly. Developing highly efficient and stable electrode materials with antipoisoning ability for ethanol electro-oxidation remains a challenge. A highly ordered periodic Au-nanoparticle (NP)-decorated bilayer TiO2 nanotube (BTNT) heteronanostructure was fabricated by a two-step anodic oxidation of Ti foil and the subsequent photoreduction of HAuCl4. The plasmon-induced charge separation on the heterointerface of Au/TiO2 electrode enhances the electrocatalytic activity and stability for the ethanol oxidation under visible light irradiation. The highly ordered periodic heterostructure on the electrode surface enhanced the light harvesting and led to the greater performance of ethanol electro-oxidation under irradiation compared with the ordinary Au NPs-decorated monolayer TiO2 nanotube (MTNT). This novel Au/TiO2 electrode also performed a self-cleaning property under visible light attributed to the enhanced electro-oxidation of the adsorbed intermediates. This light-driven enhancement of the electrochemical performances provides a development strategy for the design and construction of DAFCs.

Illuminant-adaptive color reproduction for mobile display

NASA Astrophysics Data System (ADS)

Kim, Jong-Man; Park, Kee-Hyon; Kwon, Oh-Seol; Cho, Yang-Ho; Ha, Yeong-Ho

2006-01-01

This paper proposes an illuminant-adaptive reproduction method using light adaptation and flare conditions for a mobile display. Mobile displays, such as PDAs and cellular phones, are viewed under various lighting conditions. In particular, images displayed in daylight are perceived as quite dark due to the light adaptation of the human visual system, as the luminance of a mobile display is considerably lower than that of an outdoor environment. In addition, flare phenomena decrease the color gamut of a mobile display by increasing the luminance of dark areas and de-saturating the chroma. Therefore, this paper presents an enhancement method composed of lightness enhancement and chroma compensation. First, the ambient light intensity is measured using a lux-sensor, then the flare is calculated based on the reflection ratio of the display device and the ambient light intensity. The relative cone response is nonlinear to the input luminance. This is also changed by the ambient light intensity. Thus, to improve the perceived image, the displayed luminance is enhanced by lightness linearization. In this paper, the image's luminance is transformed by linearization of the response to the input luminance according to the ambient light intensity. Next, the displayed image is compensated according to the physically reduced chroma, resulting from flare phenomena. The reduced chroma value is calculated according to the flare for each intensity. The chroma compensation method to maintain the original image's chroma is applied differently for each hue plane, as the flare affects each hue plane differently. At this time, the enhanced chroma also considers the gamut boundary. Based on experimental observations, the outer luminance-intensity generally ranges from 1,000 lux to 30,000 lux. Thus, in the case of an outdoor environment, i.e. greater than 1,000 lux, this study presents a color reproduction method based on an inverse cone response curve and flare condition. Consequently, the proposed algorithm improves the quality of the perceived image adaptive to an outdoor environment.

A computer program for analyzing the energy consumption of automatically controlled lighting systems

NASA Astrophysics Data System (ADS)

1982-01-01

A computer code to predict the performance of controlled lighting systems with respect to their energy saving capabilities is presented. The computer program provides a mathematical model from which comparisons of control schemes can be made on an economic basis only. The program does not calculate daylighting, but uses daylighting values as input. The program can analyze any of three power input versus light output relationships, continuous dimming with a linear response, continuous dimming with a nonlinear response, or discrete stepped response. Any of these options can be used with or without daylighting, making six distinct modes of control system operation. These relationships are described in detail. The major components of the program are discussed and examples are included to explain how to run the program.

Three cyanobacteriochromes work together to form a light color-sensitive input system for c-di-GMP signaling of cell aggregation.

PubMed

Enomoto, Gen; Ni-Ni-Win; Narikawa, Rei; Ikeuchi, Masahiko

2015-06-30

Cyanobacteriochromes (CBCRs) are cyanobacterial photoreceptors that have diverse spectral properties and domain compositions. Although large numbers of CBCR genes exist in cyanobacterial genomes, no studies have assessed whether multiple CBCRs work together. We recently showed that the diguanylate cyclase (DGC) activity of the CBCR SesA from Thermosynechococcus elongatus is activated by blue-light irradiation and that, when irradiated, SesA, via its product cyclic dimeric GMP (c-di-GMP), induces aggregation of Thermosynechococcus vulcanus cells at a temperature that is suboptimum for single-cell viability. For this report, we first characterize the photobiochemical properties of two additional CBCRs, SesB and SesC. Blue/teal light-responsive SesB has only c-di-GMP phosphodiesterase (PDE) activity, which is up-regulated by teal light and GTP. Blue/green light-responsive SesC has DGC and PDE activities. Its DGC activity is enhanced by blue light, whereas its PDE activity is enhanced by green light. A ΔsesB mutant cannot suppress cell aggregation under teal-green light. A ΔsesC mutant shows a less sensitive cell-aggregation response to ambient light. ΔsesA/ΔsesB/ΔsesC shows partial cell aggregation, which is accompanied by the loss of color dependency, implying that a nonphotoresponsive DGC(s) producing c-di-GMP can also induce the aggregation. The results suggest that SesB enhances the light color dependency of cell aggregation by degrading c-di-GMP, is particularly effective under teal light, and, therefore, seems to counteract the induction of cell aggregation by SesA. In addition, SesC seems to improve signaling specificity as an auxiliary backup to SesA/SesB activities. The coordinated action of these three CBCRs highlights why so many different CBCRs exist.

Enhanced Performance of GaN-Based Green Light-Emitting Diodes with Gallium-Doped ZnO Transparent Conducting Oxide

NASA Astrophysics Data System (ADS)

Oh, Min-Suk; Seo, Inseok

2014-04-01

Ga-doped ZnO (GZO) transparent conducting oxide was grown by oxygen plasma-enhanced pulsed laser deposition. GZO grown in the presence of oxygen radicals had resistivity of 1 × 10-3 Ω cm and average visible (500-700 nm) transmittance of 92.5%. A low specific contact resistance of 6.5 × 10-4 Ω cm2 of GZO on p-GaN was achieved by excimer laser annealing (ELA) treatment of p-GaN before GZO electrode deposition. The ELA-treated light emitting diode (LED) fabricated with the GZO electrode as a current-spreading layer resulted in light-output power enhanced by 56.2% at 100 mA compared with that fabricated with a conventional Ni/Au metal electrode. The high-light output and low degradation of light-output power were attributed to the decrease in contact resistance between the p-GaN layer and the GZO electrode and uniform current spreading over the p-GaN layer. In addition, low contact resistance results in a decrease of self-heat generation during current drive.

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

14 CFR 151.13 - Federal-aid Airport Program: Policy affecting landing aid requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... (ALS). (2) In-runway lighting. (3) High intensity runway lighting. (4) Runway distance markers. For the purposes of this section “approach lighting system (ALS)” is a standard configuration of aeronautical... ALS and ILS, has been programmed by the FAA with funds then available therefor; (b) An extension of 3...

LED Context Lighting System in Residential Areas

PubMed Central

Im, Kyoung-Mi

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. PMID:25101325

Enhanced retinal vasculature imaging with a rapidly configurable aperture

PubMed Central

Sapoznik, Kaitlyn A.; Luo, Ting; de Castro, Alberto; Sawides, Lucie; Warner, Raymond L.; Burns, Stephen A.

2018-01-01

In adaptive optics scanning laser ophthalmoscope (AOSLO) systems, capturing multiply scattered light can increase the contrast of the retinal microvasculature structure, cone inner segments, and retinal ganglion cells. Current systems generally use either a split detector or offset aperture approach to collect this light. We tested the ability of a spatial light modulator (SLM) as a rapidly configurable aperture to use more complex shapes to enhance the contrast of retinal structure. Particularly, we varied the orientation of a split detector aperture and explored the use of a more complex shape, the half annulus, to enhance the contrast of the retinal vasculature. We used the new approach to investigate the influence of scattering distance and orientation on vascular imaging. PMID:29541524

Regression Model for Light Weight and Crashworthiness Enhancement Design of Automotive Parts in Frontal CAR Crash

NASA Astrophysics Data System (ADS)

Bae, Gihyun; Huh, Hoon; Park, Sungho

This paper deals with a regression model for light weight and crashworthiness enhancement design of automotive parts in frontal car crash. The ULSAB-AVC model is employed for the crash analysis and effective parts are selected based on the amount of energy absorption during the crash behavior. Finite element analyses are carried out for designated design cases in order to investigate the crashworthiness and weight according to the material and thickness of main energy absorption parts. Based on simulations results, a regression analysis is performed to construct a regression model utilized for light weight and crashworthiness enhancement design of automotive parts. An example for weight reduction of main energy absorption parts demonstrates the validity of a regression model constructed.

Low-Light Image Enhancement Using Adaptive Digital Pixel Binning

PubMed Central

Yoo, Yoonjong; Im, Jaehyun; Paik, Joonki

2015-01-01

This paper presents an image enhancement algorithm for low-light scenes in an environment with insufficient illumination. Simple amplification of intensity exhibits various undesired artifacts: noise amplification, intensity saturation, and loss of resolution. In order to enhance low-light images without undesired artifacts, a novel digital binning algorithm is proposed that considers brightness, context, noise level, and anti-saturation of a local region in the image. The proposed algorithm does not require any modification of the image sensor or additional frame-memory; it needs only two line-memories in the image signal processor (ISP). Since the proposed algorithm does not use an iterative computation, it can be easily embedded in an existing digital camera ISP pipeline containing a high-resolution image sensor. PMID:26121609

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yung, Matthew M.; Stanton, Alexander R.; Iisa, Kristiina

Metal-impregnated (Ni or Ga) ZSM-5 catalysts were studied for biomass pyrolysis vapor upgrading to produce hydrocarbons using three reactors constituting a 100 000x change in the amount of catalyst used in experiments. Catalysts were screened for pyrolysis vapor phase upgrading activity in two small-scale reactors: (i) a Pyroprobe with a 10 mg catalyst in a fixed bed and (ii) a fixed-bed reactor with 500 mg of catalyst. The best performing catalysts were then validated with a larger scale fluidized-bed reactor (using ~1 kg of catalyst) that produced measurable quantities of bio-oil for analysis and evaluation of mass balances. Despite somemore » inherent differences across the reactor systems (such as residence time, reactor type, analytical techniques, mode of catalyst and biomass feed) there was good agreement of reaction results for production of aromatic hydrocarbons, light gases, and coke deposition. Relative to ZSM-5, Ni or Ga addition to ZSM-5 increased production of fully deoxygenated aromatic hydrocarbons and light gases. In the fluidized bed reactor, Ga/ZSM-5 slightly enhanced carbon efficiency to condensed oil, which includes oxygenates in addition to aromatic hydrocarbons, and reduced oil oxygen content compared to ZSM-5. Ni/ZSM-5, while giving the highest yield of fully deoxygenated aromatic hydrocarbons, gave lower overall carbon efficiency to oil but with the lowest oxygen content. Reaction product analysis coupled with fresh and spent catalyst characterization indicated that the improved performance of Ni/ZSM-5 is related to decreasing deactivation by coking, which keeps the active acid sites accessible for the deoxygenation and aromatization reactions that produce fully deoxygenated aromatic hydrocarbons. The addition of Ga enhances the dehydrogenation activity of the catalyst, which leads to enhanced olefin formation and higher fully deoxygenated aromatic hydrocarbon yields compared to unmodified ZSM-5. Catalyst characterization by ammonia temperature programmed desorption, surface area measurements, and postreaction temperature-programmed oxidation (TPO) also showed that the metal-modified zeolites retained a greater percentage of their initial acidity and surface area, which was consistent between the reactor scales. These results demonstrate that the trends observed with smaller (milligram to gram) catalyst reactors are applicable to larger, more industrially relevant (kg) scales to help guide catalyst research toward application.« less

New light Higgs boson and short-baseline neutrino anomalies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asaadi, J.; Church, E.; Guenette, R.

The low-energy excesses observed by the MiniBooNE experiment have, to date, defied a convincing explanation under the standard model even with accommodation for non-zero neutrino mass. In this paper we explore a new oscillation mechanism to explain these anomalies, invoking a light neutrinophilic Higgs boson, conceived to induce a low Dirac neutrino mass in accord with experimental limits. Beam neutrinos forward-scattering off of a locally over-dense relic neutrino background give rise to a novel matter-effect with an energy-specific resonance. An enhanced oscillation around this resonance peak produces flavor transitions which are highly consistent with the MiniBooNE neutrino- and antineutrino-mode data sets. The model provides substantially improvedmore » $$\\chi^2$$ values beyond either the no-oscillation hypothesis or the more commonly explored 3+1 sterile neutrino hypothesis. This mechanism would introduce distinctive signatures at each baseline in the upcoming SBN program at Fermilab, presenting opportunities for further exploration.« less

New light Higgs boson and short-baseline neutrino anomalies

DOE PAGES

Asaadi, J.; Church, E.; Guenette, R.; ...

2018-04-16

Here, the low-energy excesses observed by the MiniBooNE experiment have, to date, defied a convincing explanation under the standard model even with accommodation for nonzero neutrino mass. In this paper we explore a new oscillation mechanism to explain these anomalies, invoking a light neutrinophilic Higgs boson, conceived to induce a low Dirac neutrino mass in accord with experimental limits. Beam neutrinos forward scattering off of a locally overdense relic neutrino background give rise to a novel matter effect with an energy-specific resonance. An enhanced oscillation around this resonance peak produces flavor transitions which are highly consistent with the MiniBooNE neutrino-more » and antineutrino-mode data sets. The model provides substantially improved χ2 values beyond either the no-oscillation hypothesis or the more commonly explored 3+1 sterile neutrino hypothesis. This mechanism would introduce distinctive signatures at each baseline in the upcoming short-baseline neutrino program at Fermilab, presenting opportunities for further exploration.« less

New light Higgs boson and short-baseline neutrino anomalies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asaadi, J.; Church, E.; Guenette, R.

Here, the low-energy excesses observed by the MiniBooNE experiment have, to date, defied a convincing explanation under the standard model even with accommodation for nonzero neutrino mass. In this paper we explore a new oscillation mechanism to explain these anomalies, invoking a light neutrinophilic Higgs boson, conceived to induce a low Dirac neutrino mass in accord with experimental limits. Beam neutrinos forward scattering off of a locally overdense relic neutrino background give rise to a novel matter effect with an energy-specific resonance. An enhanced oscillation around this resonance peak produces flavor transitions which are highly consistent with the MiniBooNE neutrino-more » and antineutrino-mode data sets. The model provides substantially improved χ2 values beyond either the no-oscillation hypothesis or the more commonly explored 3+1 sterile neutrino hypothesis. This mechanism would introduce distinctive signatures at each baseline in the upcoming short-baseline neutrino program at Fermilab, presenting opportunities for further exploration.« less

Vision-aided Monitoring and Control of Thermal Spray, Spray Forming, and Welding Processes

NASA Technical Reports Server (NTRS)

Agapakis, John E.; Bolstad, Jon

1993-01-01

Vision is one of the most powerful forms of non-contact sensing for monitoring and control of manufacturing processes. However, processes involving an arc plasma or flame such as welding or thermal spraying pose particularly challenging problems to conventional vision sensing and processing techniques. The arc or plasma is not typically limited to a single spectral region and thus cannot be easily filtered out optically. This paper presents an innovative vision sensing system that uses intense stroboscopic illumination to overpower the arc light and produce a video image that is free of arc light or glare and dedicated image processing and analysis schemes that can enhance the video images or extract features of interest and produce quantitative process measures which can be used for process monitoring and control. Results of two SBIR programs sponsored by NASA and DOE and focusing on the application of this innovative vision sensing and processing technology to thermal spraying and welding process monitoring and control are discussed.

Bifacial Perovskite Solar Cells Featuring Semitransparent Electrodes.

PubMed

Hanmandlu, Chintam; Chen, Chien-Yu; Boopathi, Karunakara Moorthy; Lin, Hao-Wu; Lai, Chao-Sung; Chu, Chih-Wei

2017-09-27

Inorganic-organic hybrid perovskite solar cells (PSCs) are promising devices for providing future clean energy because of their low cost, ease of fabrication, and high efficiencies, similar to those of silicon solar cells. These materials have been investigated for their potential use in bifacial PSCs, which can absorb light from both sides of the electrodes. Here, we fabricated bifacial PSCs featuring transparent BCP/Ag/MoO 3 rear electrodes, which we formed through low-temperature processing using thermal evaporation methods. We employed a comprehensive optical distribution program to calculate the distributions of the optical field intensities with constant thicknesses of the absorbing layer in the top electrode configuration. The best PSC having a transparent BCP/Ag/MoO 3 electrode achieved PCEs of 13.49% and 9.61% when illuminated from the sides of the indium tin oxide and BCP/Ag/MoO 3 electrodes, respectively. We observed significant power enhancement when operating this PSC using mirror reflectors and bifacial light illumination from both sides of the electrodes.

The formation of the light-sensing compartment of cone photoreceptors coincides with a transcriptional switch

PubMed Central

Daum, Janine M; Keles, Özkan; Holwerda, Sjoerd JB; Kohler, Hubertus; Rijli, Filippo M

2017-01-01

High-resolution daylight vision is mediated by cone photoreceptors. The molecular program responsible for the formation of their light sensor, the outer segment, is not well understood. We correlated daily changes in ultrastructure and gene expression in postmitotic mouse cones, between birth and eye opening, using serial block-face electron microscopy (EM) and RNA sequencing. Outer segments appeared rapidly at postnatal day six and their appearance coincided with a switch in gene expression. The switch affected over 14% of all expressed genes. Genes that switched off were rich in transcription factors and neurogenic genes. Those that switched on contained genes relevant for cone function. Chromatin rearrangements in enhancer regions occurred before the switch was completed, but not after. We provide a resource comprised of correlated EM, RNAseq, and ATACseq data, showing that the growth of a key compartment of a postmitotic cell involves an extensive switch in gene expression and chromatin accessibility. PMID:29106373

Synthesis and energy applications of mesoporous titania thin films

NASA Astrophysics Data System (ADS)

Islam, Syed Z.

The optical and electronic properties of TiO2 thin films provide tremendous opportunities in several applications including photocatalysis, photovoltaics and photoconductors for energy production. Despite many attractive features of TiO2, critical challenges include the innate inability of TiO2 to absorb visible light and the fast recombination of photoexcited charge carriers. In this study, mesoporous TiO2 thin films are modified by doping using hydrogen and nitrogen, and sensitization using graphene quantum dot sensitization. For all of these modifiers, well-ordered mesoporous titania films were synthesized by surfactant templated sol-gel process. Two methods: hydrazine and plasma treatments have been developed for nitrogen and hydrogen doping in the mesoporous titania films for band gap reduction, visible light absorption and enhancement of photocatalytic activity. The hydrazine treatment in mesoporous titania thin films suggests that hydrazine induced doping is a promising approach to enable synergistic incorporation of N and Ti3+ into the lattice of surfactant-templated TiO2 films and enhanced visible light photoactivity, but that the benefits are limited by gradual mesostructure deterioration. The plasma treated nitrogen doped mesoporous titania showed about 240 times higher photoactivity compared to undoped film in hydrogen production from photoelectrochemical water splitting under visible light illumination. Plasma treated hydrogen doped mesoporous titania thin films has also been developed for enhancement of visible light absorption. Hydrogen treatment has been shown to turn titania (normally bright white) black, indicating vastly improved visible light absorption. The cause of the color change and its effectiveness for photocatalysis remain open questions. For the first time, we showed that a significant amount of hydrogen is incorporated in hydrogen plasma treated mesoporous titania films by neutron reflectometry measurements. In addition to the intrinsic modification of titania by doping, graphene quantum dot sensitization in mesoporous titania film was also investigated for visible light photocatalysis. Graphene quantum dot sensitization and nitrogen doping of ordered mesoporous titania films showed synergistic effect in water splitting due to high surface area, band gap reduction, enhanced visible light absorption, and efficient charge separation and transport. This study suggests that plasma based doping and graphene quantum dot sensitization are promising strategies to reduce band gap and enhance visible light absorption of high surface area surfactant templated mesoporous titania films, leading to superior visible-light driven photoelectrochemical hydrogen production. The results demonstrate the importance of designing and manipulating the energy band alignment in composite nanomaterials for fundamentally improving visible light absorption, charge separation and transport, and thereby photoelectrochemical properties.

Effect of 710 nm visible light irradiation on neurite outgrowth in primary rat cortical neurons following ischemic insult

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Dong-Hee; Department of Medical Science, Konkuk University School of Medicine, Seoul; Lee, Kyoung-Hee

2012-06-01

Highlights: Black-Right-Pointing-Pointer 710 nm wavelength light (LED) has a protective effect in the stroke animal model. Black-Right-Pointing-Pointer We determined the effects of LED irradiation in vitro stroke model. Black-Right-Pointing-Pointer LED treatment promotes the neurite outgrowth through MAPK activation. Black-Right-Pointing-Pointer The level of synaptic markers significantly increased with LED treatment. Black-Right-Pointing-Pointer LED treatment protects cell death in the in vitro stroke model. -- Abstract: Objective: We previously reported that 710 nm Light-emitting Diode (LED) has a protective effect through cellular immunity activation in the stroke animal model. However, whether LED directly protects neurons suffering from neurodegeneration was entirely unknown. Therefore, wemore » sought to determine the effects of 710 nm visible light irradiation on neuronal protection and neuronal outgrowth in an in vitro stroke model. Materials and methods: Primary cultured rat cortical neurons were exposed to oxygen-glucose deprivation (OGD) and reoxygenation and normal conditions. An LED array with a peak wavelength of 710 nm was placed beneath the covered culture dishes with the room light turned off and were irradiated accordingly. LED treatments (4 min at 4 J/cm{sup 2} and 50 mW/cm{sup 2}) were given once to four times within 8 h at 2 h intervals for 7 days. Mean neurite density, mean neurite diameter, and total fiber length were also measured after microtubule associated protein 2 (MAP2) immunostaining using the Axio Vision program. Synaptic marker expression and MAPK activation were confirmed by Western blotting. Results: Images captured after MAP2 immunocytochemistry showed significant (p < 0.05) enhancement of post-ischemic neurite outgrowth with LED treatment once and twice a day. MAPK activation was enhanced by LED treatment in both OGD-exposed and normal cells. The levels of synaptic markers such as PSD 95, GAP 43, and synaptophysin significantly increased with LED treatment in both OGD-exposed and normal cells (p < 0.05). Conclusion: Our data suggest that LED treatment may promote synaptogenesis through MAPK activation and subsequently protect cell death in the in vitro stroke model.« less

NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Supplement: Research on Materials for the High Speed Civil Transport

NASA Technical Reports Server (NTRS)

Gangloff, Richard P.; Starke, Edgar A., Jr.

1997-01-01

This report documents the progress achieved over the past 6 to 12 months on four graduate student projects conducted within the NASA-UVA Light Aerospace Alloy and Structures Technology Program. These studies were aimed specifically at light metallic alloy issues relevant to the High Speed Civil Transport. Research on Hydrogen-Enhanced Fracture of High-Strength Titanium Alloy Sheet refined successfully the high resolution R-curve method necessary to characterize initiation and growth fracture toughnesses. For solution treated and aged Low Cost Beta without hydrogen precharging, fracture is by ductile transgranular processes at 25 C, but standardized initiation toughnesses are somewhat low and crack extension is resolved at still lower K-levels. This fracture resistance is degraded substantially, by between 700 and 1000 wppm of dissolved hydrogen, and a fracture mode change is affected. The surface oxide on P-titanium alloys hinders hydrogen uptake and complicates the electrochemical introduction of low hydrogen concentrations that are critical to applications of these alloys. Ti-15-3 sheet was obtained for study during the next reporting period. Research on Mechanisms of deformation and Fracture in High-Strength Titanium Alloys is examining the microstructure and fatigue resistance of very thin sheet. Aging experiments on 0. 14 mm thick (0.0055 inch) foil show microstructural agility that may be used to enhance fatigue performance. Fatigue testing of Ti-15-3 sheet has begun. The effects of various thermo-mechanical processing regimens on mechanical properties will be examined and deformation modes identified. Research on the Effect of Texture and Precipitates on Mechanical Property Anisotropy of Al-Cu-Mg-X and Al-Cu alloys demonstrated that models predict a minor influence of stress-induced alignment of Phi, caused by the application of a tensile stress during aging, on the yield stress anisotropy of both modified AA2519 and a model Al-Cu binary alloy. This project is no longer included in the NASA-UVA LAST program. Research on the Creep Behavior and Microstructural stability of Al-Cu-Mg-Ag and Al-Cu-Li-Mg-Ag showed that the creep resistance of three candidate aluminum alloys (C415, C416 and ML377) was much superior compared to that of the current Concorde alloy, AA2618. Creep induced change in precipitates at grain boundaries was observed in the alloy which exhibits the highest creep strain of the three examined. The other two alloys developed no detectable microstructural changes at grain boundaries under the creep conditions tested.

Enhancing light-harvesting power with coherent vibrational interactions: A quantum heat engine picture

NASA Astrophysics Data System (ADS)

Killoran, N.; Huelga, S. F.; Plenio, M. B.

2015-10-01

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's relevance in parameter regimes connected to natural light-harvesting structures.

[Ru(bipy)3]2+ nanoparticle-incorporate dental light cure resin to promote photobiomodulation therapy for enhanced vital pulp tissue repair

NASA Astrophysics Data System (ADS)

Mosca, Rodrigo C.; Young, Nicholas; Zeituni, Carlos A.; Arany, Praveen R.

2018-02-01

The use of nanoparticle on dental light cure resin is not new, currently several compounds (nanoadditives) are used to promote better communication between the restorative material and biological tissues. The interest for this application is growing up to enhance mechanical proprieties to dental tissue cells regeneration. Bioactive nanoparticles and complex compounds with multiple functions are the major target for optimizing the restorative materials. In this work, we incorporate [Ru(bipy)3]2+ nanoparticles, that absorbs energy at 450 nm (blue-light) and emits strongly at 620 nm (red-light), in PLGA Microspheres and insert it in Dental Light Cure Resin to promote the Photobiomodulation Therapy (PBM) effects to accelerate dental pulp repair by in vitro using cytotoxicity and proliferation assay.

Diffractive intermediate layer enables broadband light trapping for high efficiency ultrathin c-Si tandem cells

NASA Astrophysics Data System (ADS)

Li, Guijun; Ho, Jacob Y. L.; Li, He; Kwok, Hoi-Sing

2014-06-01

Light management through the intermediate reflector in the tandem cell configuration is of great practical importance for achieving high stable efficiency and also low cost production. So far, however, the intermediate reflectors employed currently are mainly focused on the light absorption enhancement of the top cell. Here, we present a diffractive intermediate layer that allows for light trapping over a broadband wavelength for the ultrathin c-Si tandem solar cell. Compared with the standard intermediate reflector, this nanoscale architectural intermediate layer results in a 35% and 21% remarkable enhancement of the light absorption in the top (400-800 nm) and bottom (800-1100 nm) cells simultaneously, and ultrathin c-Si tandem cells with impressive conversion efficiency of 13.3% are made on the glass substrate.

The aspect ratio effects on the performances of GaN-based light-emitting diodes with nanopatterned sapphire substrates

NASA Astrophysics Data System (ADS)

Kao, Chien-Chih; Su, Yan-Kuin; Lin, Chuing-Liang; Chen, Jian-Jhong

2010-07-01

The nanopatterned sapphire substrates (NPSSs) with aspect ratio that varied from 2.00 to 2.50 were fabricated by nanoimprint lithography. We could improve the epitaxial film quality and enhance the light extraction efficiency by NPSS technique. In this work, the aspect ratio effects on the performances of GaN-based light-emitting diodes (LEDs) with NPSS were investigated. The light output enhancement of GaN-based LEDs with NPSS was increased from 11% to 27% as the aspect ratio of the NPSS increases from 2.00 to 2.50. Owing to the same improvement of crystalline quality by using various aspect ratios of NPSS, these results indicated that the aspect ratio of the NPSS is strongly related to the light extraction efficiency.

Light-adaptation of photosystem II is mediated by the plastoquinone pool.

PubMed

Ahrling, Karin A; Peterson, Sindra

2003-07-01

During the first few enzymatic turnovers after dark-adaptation of photosystem II (PSII), the relaxation rate of the EPR signals from the Mn cluster and Y(D)(*) are significantly enhanced. This light-adaptation process has been suggested to involve the appearance of a new paramagnet on the PSII donor side [Peterson, S., Ahrling, K., Högblom, J., and Styring, S. (2003) Biochemistry 42, 2748-2758]. In the present study, a correlation is established between the observed relaxation enhancement and the redox state of the quinone pool. It is shown that the addition of quinol to dark-adapted PSII membrane fragments induces relaxation enhancement already after a single oxidation of the Mn, comparable to that observed after five oxidations in samples with quinones (PPBQ or DQ) added. The saturation behavior of Y(D)(*) revealed that with quinol added in the dark, a single flash was necessary for the relaxation enhancement to occur. The quinol-induced relaxation enhancement of PSII was also activated by illumination at 200 K. Whole thylakoids, with no artificial electron acceptor present but with an intact plastoquinone pool, displayed the same relaxation enhancement on the fifth flash as membrane fragments with exogenous quinones present. We conclude that (i) reduction of the quinone pool induces the relaxation enhancement of the PSII donor-side paramagnets, (ii) light is required for the quinol to effect the relaxation enhancement, and (iii) light-adaptation occurs in the intact thylakoid system, when the endogenous plastoquinone pool is gradually reduced by PSII turnover. It seems clear that a species on the PSII donor side is reduced by the quinol, to become a potent paramagnetic relaxer. On the basis of XANES reports, we suggest that this species may be the Mn ions not involved in the cyclic redox changes of the oxygen-evolving complex.

Generation of reactive oxygen species and charge carriers in plasmonic photocatalytic Au@TiO2 nanostructures with enhanced activity.

PubMed

He, Weiwei; Cai, Junhui; Jiang, Xiumei; Yin, Jun-Jie; Meng, Qingbo

2018-06-13

The combination of semiconductor and plasmonic nanostructures, endowed with high efficiency light harvesting and surface plasmon confinement, has been a promising way for efficient utilization of solar energy. Although the surface plasmon resonance (SPR) assisted photocatalysis has been extensively studied, the photochemical mechanism, e.g. the effect of SPR on the generation of reactive oxygen species and charge carriers, is not well understood. In this study, we take Au@TiO2 nanostructures as a plasmonic photocatalyst to address this critical issue. The Au@TiO2 core/shell nanostructures with tunable SPR property were synthesized by the templating method with post annealing thermal treatment. It was found that Au@TiO2 nanostructures exhibit enhanced photocatalytic activity in either sunlight or visible light (λ > 420 nm). Electron spin resonance spectroscopy with spin trapping and spin labeling was used to investigate the enhancing effect of Au@TiO2 on the photo-induced reactive oxygen species and charge carriers. The formation of Au@TiO2 core/shell nanostructures resulted in a dramatic increase in light-induced generation of hydroxyl radicals, singlet oxygen, holes and electrons, as compared with TiO2 alone. This enhancement under visible light (λ > 420 nm) irradiation may be dominated by SPR induced local electrical field enhancement, while the enhancement under sunlight irradiation is dominated by the higher electron transfer from TiO2 to Au. These results unveiled that the superior photocatalytic activity of Au@TiO2 nanostructures correlates with enhanced generation of reactive oxygen species and charge carriers.

Inquiry learning: Students' perception of light wave phenomena in an informal environment

NASA Astrophysics Data System (ADS)

Ford, Ken

This study involved identifying students' perception of light phenomena and determined if they learned the scientific concepts of light that were presented to them by an interactive science exhibit. The participants in this study made scientific inquiry about light by using a powerful white light source, a prism, converging lenses, diverging lenses, concave and convex mirrors in an informal science setting. The sample used in the study consisted of 40 subjects (15 males and 25 females) in a college program at a University located in the Southern region of the United States. The participants were selected using a convenient sampling process from a population enrolled in a pre-calculus class and a physics class. The participants were engaged in pretest on light wave phenomena using the Inquiry Laboratory Light Island exhibit. After the pretest, the participants were engaged in activities, where they reflected white light off the surface of concave and convex mirrors, refracted white light through converging and diverging lens, and passed white light through a prism. They also made observations of the behavior and characteristics of light from the patterns that it created. After three weeks, the participants were given the Inquiry Laboratory Light Island exhibit posttest. The findings of the study indicated that the means yielded a higher average for the participants' posttest scores. The t-Test results were statistically significant, which confirmed that the concepts of light wave phenomena were perceived and learned by the participants. The Inquiry Laboratory survey questions analyzed using the chi-square test suggested that participants were in agreement with the concepts about light. In addition, Cramer's phi and Cramer's V suggested a moderate relationship and association between the genders of the participants on the concepts of light wave phenomena. Furthermore, the interview and observation protocol processes confirmed that students perceived and learned the science concepts of light wave phenomena by the way they responded to the researcher's interview questions. Implications from the study suggested that further study be carried out on the learning process in an informal science setting and should be supported by corporations, businesses, educational institutions, and organizations. Although the findings from this study aided in the development of a structured approach that enhanced student motivation, interest, and learning about light waves in physics/physical science there is still a need to do more research in this area.

Differential sensitivity of duckweeds (Lemnaceae) to sulfite: I. Carbon assimilation and frond replication rate as factors influencing sulfite phytotoxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takemoto, B.K.; Noble, R.D.

1986-01-01

The thiol content and hydrogen sulfide emission responses of duckweeds (Lemnaceae) differentially sensitive to sulfite enrichment were studied, at two levels of irradiance. The objectives were to examine the relationship of selected parameters of sulfite metabolism to sulfite sensitivity, and the role of light level on modifying sulfite metabolic responses and duckweed sulfite sensitivity. Under low light, thiol contents were increased 30 to 40% by sulfite in all three duckweeds examined. Hydrogen sulfide was emitted by all three species, and emission rates were up to four times higher in the sulfite tolerant duckweed Lemna valdiviana. Under high light, sulfite increasedmore » thiol contents by an average of 40% in L. valdiviana and Spirodela oligorhiza, but only 20% in Lemna gibba. The greater light enhancement of thiol content exhibited by L. valdiviana and S. oligorhiza may be indicative of larger or more numerous sulfur sinks. Hydrogen sulfide emission rates were also enhanced under high light, and L. gibba exhibited a 17% increase relative to its low light rate. In comparison, L. valdiviana and S. oligorhiza exhibited 55% and 60% increases, respectively. The ability to form elevated internal thiols and hydrogen sulfide were found to be important to sulfite tolerance in duckweeds. Enhancement of both processes under high light may contribute to increased tolerance of sulfite in L. gibba and S. oligorhiza. It is hypothesized that thiol production and hydrogen sulfide emission are important sulfite detoxification processes in duckweeds, and enhancement of sulfite detoxification is fundamental to the modification of duckweed sulfite sensitivity by the photoenvironment. 25 refs., 3 tabs.« less

Ordered polymer nanofibers enhance output brightness in bilayer light-emitting field-effect transistors.

PubMed

Hsu, Ben B Y; Seifter, Jason; Takacs, Christopher J; Zhong, Chengmei; Tseng, Hsin-Rong; Samuel, Ifor D W; Namdas, Ebinazar B; Bazan, Guillermo C; Huang, Fei; Cao, Yong; Heeger, Alan J

2013-03-26

Polymer light emitting field effect transistors are a class of light emitting devices that reveal interesting device physics. Device performance can be directly correlated to the most fundamental polymer science. Control over surface properties of the transistor dielectric can dramatically change the polymer morphology, introducing ordered phase. Electronic properties such as carrier mobility and injection efficiency on the interface can be promoted by ordered nanofibers in the polymer. Moreover, by controlling space charge in the polymer interface, the recombination zone can be spatially extended and thereby enhance the optical output.

Dynamical Cooper pairing in nonequilibrium electron-phonon systems

DOE PAGES

Knap, Michael; Babadi, Mehrtash; Refael, Gil; ...

2016-12-08

In this paper, we analyze Cooper pairing instabilities in strongly driven electron-phonon systems. The light-induced nonequilibrium state of phonons results in a simultaneous increase of the superconducting coupling constant and the electron scattering. We demonstrate that the competition between these effects leads to an enhanced superconducting transition temperature in a broad range of parameters. Finally, our results may explain the observed transient enhancement of superconductivity in several classes of materials upon irradiation with high intensity pulses of terahertz light, and may pave new ways for engineering high-temperature light-induced superconducting states.

The disease management program for type 2 diabetes in Germany enhances process quality of diabetes care - a follow-up survey of patient's experiences

PubMed Central

2010-01-01

Background In summer 2003 a disease management program (DMP) for type 2 diabetes was introduced on a nationwide basis in Germany. Patient participation and continuity of care within the DMP are important factors to achieve long-term improvements in clinical endpoints. Therefore it is of interest, if patients experience any positive or negative effects of the DMP on their treatment that would support or hamper further participation. The main objective of the study was to find out if the German Disease Management Program (DMP) for type 2 diabetes improves process and outcome quality of medical care for patients in the light of their subjective experiences over a period of one year. Methods Cohort study with a baseline interview and a follow-up after 10.4 ± 0.64 months. Data on process and outcome measures were collected by telephone interviews with 444 patients enrolled and 494 patients not enrolled in the German DMP for type 2 diabetes. Data were analyzed by multivariate logistic regression analyses. Results DMP enrolment was significantly associated with a higher process quality of care. At baseline enrolled patients more often reported that they had attended a diabetes education course (OR = 3.4), have ≥ 4 contacts/year with the attending physician (OR = 3.3), have at least one annual foot examination (OR = 3.1) and one referral to an ophthalmologist (OR = 3.4) and possess a diabetes passport (OR = 2.4). Except for the annual referral to an ophthalmologist these parameters were also statistically significant at follow-up. In contrast, no differences between enrolled and not enrolled patients were found concerning outcome quality indicators, e.g. self-rated health, Glycated hemoglobin (GHb) and blood pressure. However, 16-36% of the DMP participants reported improvements of body weight and/or GHb and/or blood pressure values due to enrolment - unchanged within one year of follow-up. Conclusions In the light of patient's experiences the DMP enhances the process quality of medical care for type 2 diabetes in Germany. The lack of significant differences in outcome quality between enrolled and not enrolled patients might be due to the short program duration. Our data suggest that the DMP for type 2 diabetes should not be withdrawn unless an evidently more promising approach is found. PMID:20199685

The disease management program for type 2 diabetes in Germany enhances process quality of diabetes care - a follow-up survey of patient's experiences.

PubMed

Schäfer, Ingmar; Küver, Claudia; Gedrose, Benjamin; Hoffmann, Falk; Russ-Thiel, Barbara; Brose, Hans-Peter; van den Bussche, Hendrik; Kaduszkiewicz, Hanna

2010-03-03

In summer 2003 a disease management program (DMP) for type 2 diabetes was introduced on a nationwide basis in Germany. Patient participation and continuity of care within the DMP are important factors to achieve long-term improvements in clinical endpoints. Therefore it is of interest, if patients experience any positive or negative effects of the DMP on their treatment that would support or hamper further participation. The main objective of the study was to find out if the German Disease Management Program (DMP) for type 2 diabetes improves process and outcome quality of medical care for patients in the light of their subjective experiences over a period of one year. Cohort study with a baseline interview and a follow-up after 10.4 +/- 0.64 months. Data on process and outcome measures were collected by telephone interviews with 444 patients enrolled and 494 patients not enrolled in the German DMP for type 2 diabetes. Data were analyzed by multivariate logistic regression analyses. DMP enrolment was significantly associated with a higher process quality of care. At baseline enrolled patients more often reported that they had attended a diabetes education course (OR = 3.4), have > or = 4 contacts/year with the attending physician (OR = 3.3), have at least one annual foot examination (OR = 3.1) and one referral to an ophthalmologist (OR = 3.4) and possess a diabetes passport (OR = 2.4). Except for the annual referral to an ophthalmologist these parameters were also statistically significant at follow-up. In contrast, no differences between enrolled and not enrolled patients were found concerning outcome quality indicators, e.g. self-rated health, Glycated hemoglobin (GHb) and blood pressure. However, 16-36% of the DMP participants reported improvements of body weight and/or GHb and/or blood pressure values due to enrolment - unchanged within one year of follow-up. In the light of patient's experiences the DMP enhances the process quality of medical care for type 2 diabetes in Germany. The lack of significant differences in outcome quality between enrolled and not enrolled patients might be due to the short program duration. Our data suggest that the DMP for type 2 diabetes should not be withdrawn unless an evidently more promising approach is found.

Lessons learned from the implementation of a time-limited, large-scale nicotine replacement therapy giveaway program in New York City.

PubMed

Davis, Karen A; Coady, Micaela H; Mbamalu, Ijeoma G; Sacks, Rachel; Kilgore, Elizabeth A

2013-09-01

Since 2006, the New York City (NYC) Department of Health and Mental Hygiene has conducted the Nicotine Patch and Gum Program (NPGP) in collaboration with 311, NYC's non-emergency information line. In two prior years, the program was conducted in collaboration with the New York State (NYS) Smokers' Quitline and with community-based organizations. The NPGP is an annual, brief, population-based nicotine replacement therapy (NRT) giveaway for NYC residents, complementing the NYS Quitline's year-round NRT distribution program. Since 2006, 168,000 smokers have enrolled, with the largest number of enrollees in 2010 (n = 40,000) and the smallest number in 2009 (n = 28,000). A 2003 program evaluation demonstrated that smokers who received NRT through the NPGP had higher quit rates than smokers who did not receive NRT; these results were replicated in 2006 and 2008. Lessons learned from implementing the NPGP include: 1) time-limited NRT interventions are important complements to year-round NRT distribution; 2) expanding NRT distribution to light smokers increases treatment reach; and 3) employing multiple enrollment mechanisms, including telephone and online options, extends program reach to diverse groups of smokers. The NPGP provides a model for other jurisdictions considering implementing time-limited, population-based NRT programs as a complementary strategy to enhance ongoing tobacco control efforts.

Bacteriostatic influence of red laser light on the growth of Staphylococcus aureus and photodynamic enhancement of this effect with Photoditazine

NASA Astrophysics Data System (ADS)

Egorova, A. V.; Brill, G. E.; Bugaeva, I. O.; Tuchina, E. S.; Ponomaryov, G. V.; Ushakova, O. V.

2018-04-01

The influence of red laser irradiation on the growth of colonies of Staphylococcus aureus and photodynamic effect of the photosensitizer Photoditazine were performed. It was established that the emission of red laser light caused an inhibition of bacterial growth. This effect on standard strain of Staphylococcus aureus was evident only when relatively high doses of radiation (180 j/cm2). Photosensitivity of the methicillin-resistant strains was much higher: bacteriostatic effect of red light was observed already at the dose of 60 j/cm2 . Pre-treatment of bacterial cells by Photoditazine significantly enhances the inhibitory effect of the laser light.

Anomalous change in dielectric constant of CaCu3Ti4O12 under violet-to-ultraviolet irradiation

NASA Astrophysics Data System (ADS)

Masingboon, C.; Eknapakul, T.; Suwanwong, S.; Buaphet, P.; Nakajima, H.; Mo, S.-K.; Thongbai, P.; King, P. D. C.; Maensiri, S.; Meevasana, W.

2013-05-01

The influence of light illumination on the dielectric constant of CaCu3Ti4O12 (CCTO) polycrystals is studied in this work. When exposed to 405-nm laser light, a reversible enhancement in the room temperature capacitance as high as 22% was observed, suggesting application of light-sensitive capacitance devices. To uncover the microscopic mechanisms mediating this change, we performed electronic structure measurements, using photoemission spectroscopy, and measured the electrical conductivity of the CCTO samples under different conditions of light exposure and oxygen partial pressure. Together, these results suggest that the large capacitance enhancement is driven by oxygen vacancies induced by the irradiation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Gaoming; Key Laboratory of OptoElectronic Science and Technology for Medicine, Ministry of Education, Fujian Normal University, Fuzhou 350007; Gao, Fei

Multiple stimulated emission fluorescence photoacoustic (MSEF-PA) phenomenon is demonstrated in this letter. Under simultaneous illumination of pumping light and stimulated emission light, the fluorescence emission process is speeded up by the stimulated emission effect. This leads to nonlinear enhancement of photoacoustic signal while the quantity of absorbed photons is more than that of fluorescent molecules illuminated by pumping light. The electronic states' specificity of fluorescent molecular can also be labelled by the MSEF-PA signals, which can potentially be used to obtain fluorescence excitation spectrum in deep scattering tissue with nonlinearly enhanced photoacoustic detection. In this preliminary study, the fluorescence excitationmore » spectrum is reconstructed by MSEF-PA signals through sweeping the wavelength of exciting light, which confirms the theoretical derivation well.« less

Multi-layer coating of SiO2 nanoparticles to enhance light absorption by Si solar cells

NASA Astrophysics Data System (ADS)

Nam, Yoon-Ho; Um, Han-Don; Park, Kwang-Tae; Shin, Sun-Mi; Baek, Jong-Wook; Park, Min-Joon; Jung, Jin-Young; Zhou, Keya; Jee, Sang-Won; Guo, Zhongyi; Lee, Jung-Ho

2012-06-01

We found that multi-layer coating of a Si substrate with SiO2 dielectric nanoparticles (NPs) was an effective method to suppress light reflection by silicon solar cells. To suppress light reflection, two conditions are required for the coating: 1) The difference of refractive indexes between air and Si should be alleviated, and 2) the quarter-wavelength antireflection condition should be satisfied while avoiding intrinsic absorption loss. Light reflection was reduced due to destructive interference at certain wavelengths that depended on the layer thickness. For the same thickness dielectric layer, smaller NPs enhanced antireflectance more than larger NPs due to a decrease in scattering loss by the smaller NPs.

Nano-honeycomb structured transparent electrode for enhanced light extraction from organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Shi, Xiao-Bo; Qian, Min; Wang, Zhao-Kui; Liao, Liang-Sheng

2015-06-01

A universal nano-sphere lithography method has been developed to fabricate nano-structured transparent electrode, such as indium tin oxide (ITO), for light extraction from organic light-emitting diodes (OLEDs). Perforated SiO2 film made from a monolayer colloidal crystal of polystyrene spheres and tetraethyl orthosilicate sol-gel is used as a template. Ordered nano-honeycomb pits on the ITO electrode surface are obtained by chemical etching. The proposed method can be utilized to form large-area nano-structured ITO electrode. More than two folds' enhancement in both current efficiency and power efficiency has been achieved in a red phosphorescent OLED which was fabricated on the nano-structured ITO substrate.

NASA-UVA light aerospace alloy and structures technology program (LA2ST)

NASA Technical Reports Server (NTRS)

Gangloff, Richard P.; Starke, Edger A., Jr.

1996-01-01

This progress report covers achievements made between January 1 and June 30, 1966 on the NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. . The accomplishments presented in this report are: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals, (2) Aerospace Materials Science, and (3) Mechanics of Materials for Light Aerospace Structures. Collective accomplishments between January and June of 1996 include: 4 journal or proceedings publications, 1 NASA progress report, 4 presentations at national technical meetings, and 2 PhD dissertations published.

ELiXIR—Solid-State Luminaire With Enhanced Light Extraction by Internal Reflection

NASA Astrophysics Data System (ADS)

Allen, Steven C.; Steckl, Andrew J.

2007-06-01

A phosphor-converted light-emitting diode (pcLED) luminaire featuring enhanced light extraction by internal reflection (ELiXIR) with efficacy of 60 lm/W producing 18 lumens of yellowish green light at 100 mA is presented. The luminaire consists of a commercial blue high power LED, a polymer hemispherical shell lens with interior phosphor coating, and planar aluminized reflector. High extraction efficiency of the phosphor-converted light is achieved by separating the phosphor from the LED and using internal reflection to steer the light away from lossy reflectors and the LED package and out of the device. At 10 and 500 mA, the luminaire produces 2.1 and 66 lumens with efficacies of 80 and 37 lm/W, respectively. Technological improvements over existing commercial LEDs, such as more efficient pcLED packages or, alternatively, higher efficiency green or yellow for color mixing, will be essential to achieving 150 200 lm/W solid-state lighting. Advances in both areas are demonstrated.

34 CFR 225.3 - What regulations apply to the Credit Enhancement for Charter School Facilities Program?

Code of Federal Regulations, 2013 CFR

2013-07-01

... Charter School Facilities Program? 225.3 Section 225.3 Education Regulations of the Offices of the... ENHANCEMENT FOR CHARTER SCHOOL FACILITIES PROGRAM General § 225.3 What regulations apply to the Credit Enhancement for Charter School Facilities Program? The following regulations apply to the Credit Enhancement...

34 CFR 225.3 - What regulations apply to the Credit Enhancement for Charter School Facilities Program?

Code of Federal Regulations, 2014 CFR

2014-07-01

... Charter School Facilities Program? 225.3 Section 225.3 Education Regulations of the Offices of the... ENHANCEMENT FOR CHARTER SCHOOL FACILITIES PROGRAM General § 225.3 What regulations apply to the Credit Enhancement for Charter School Facilities Program? The following regulations apply to the Credit Enhancement...

34 CFR 225.3 - What regulations apply to the Credit Enhancement for Charter School Facilities Program?

Code of Federal Regulations, 2012 CFR

2012-07-01

... Charter School Facilities Program? 225.3 Section 225.3 Education Regulations of the Offices of the... ENHANCEMENT FOR CHARTER SCHOOL FACILITIES PROGRAM General § 225.3 What regulations apply to the Credit Enhancement for Charter School Facilities Program? The following regulations apply to the Credit Enhancement...

34 CFR 225.3 - What regulations apply to the Credit Enhancement for Charter School Facilities Program?

Code of Federal Regulations, 2011 CFR

2011-07-01

... Charter School Facilities Program? 225.3 Section 225.3 Education Regulations of the Offices of the... ENHANCEMENT FOR CHARTER SCHOOL FACILITIES PROGRAM General § 225.3 What regulations apply to the Credit Enhancement for Charter School Facilities Program? The following regulations apply to the Credit Enhancement...

34 CFR 225.3 - What regulations apply to the Credit Enhancement for Charter School Facilities Program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Charter School Facilities Program? 225.3 Section 225.3 Education Regulations of the Offices of the... ENHANCEMENT FOR CHARTER SCHOOL FACILITIES PROGRAM General § 225.3 What regulations apply to the Credit Enhancement for Charter School Facilities Program? The following regulations apply to the Credit Enhancement...

A facile one-step electrochemical strategy of doping iron, nitrogen, and fluorine into titania nanotube arrays with enhanced visible light photoactivity.

PubMed

Hua, Zulin; Dai, Zhangyan; Bai, Xue; Ye, Zhengfang; Gu, Haixin; Huang, Xin

2015-08-15

Highly ordered iron, nitrogen, and fluorine tri-doped TiO2 (Fe, (N, F)-TiO2) nanotube arrays were successfully synthesized by a facile one-step electrochemical method in an NH4F electrolyte containing Fe ions. The morphology, structure, composition, and photoelectrochemical property of the as-prepared nanotube arrays were characterized by various methods. The photoactivities of the samples were evaluated by the degradation of phenol in an aqueous solution under visible light. Tri-doped TiO2 showed higher photoactivities than undoped TiO2 under visible light. The optimum Fe(3+) doping amount at 0.005M exhibited the highest photoactivity and exceeded that of undoped TiO2 by a factor of 20 times under visible light. The formation of N 2p level near the valence band (VB) contributed to visible light absorption. Doping fluorine and appropriate Fe(3+) ions reduced the photogenerated electrons-holes recombination rate and enhanced visible light photoactivity. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results indicated the presence of synergistic effects in Fe, N, and F tri-doped TiO2, which enhanced visible light photoactivity. The Fe, (N, F)-TiO2 photocatalyst exhibited high stability. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication and Characterization of Surrogate Fuel Particles Using the Spark Erosion Method

NASA Astrophysics Data System (ADS)

Metzger, Kathryn E.

In light of the disaster at the Fukushima Daiichi Nuclear Plant, the Department of Energy's Advanced Fuels Program has shifted its interest from enhanced performance fuels to enhanced accident tolerance fuels. Dispersion fuels possess higher thermal conductivities than traditional light water reactor fuel and as a result, offer improved safety margins. The benefits of a dispersion fuel are due to the presence of the secondary non-fissile phase (matrix), which serves as a barrier to fission products and improves the overall thermal performance of the fuel. However, the presence of a matrix material reduces the fuel volume, which lowers the fissile content of dispersion. This issue can be remedied through the development of higher density fuel phases or through an optimization of fuel particle size and volume loading. The latter requirement necessitates the development of fabrication methods to produce small, micron-order fuel particles. This research examines the capabilities of the spark erosion process to fabricate particles on the order of 10 μm. A custom-built spark erosion device by CT Electromechanica was used to produce stainless steel surrogate fuel particles in a deionized water dielectric. Three arc intensities were evaluated to determine the effect on particle size. Particles were filtered from the dielectric using a polycarbonate membrane filter and vacuum filtration system. Fabricated particles were characterized via field emission scanning electron microscopy (FESEM), laser light particle size analysis, energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), and gas pycnometry. FESEM images reveal that the spark erosion process produces highly spherical particles on the order of 10 microns. These findings are substantiated by the results of particle size analysis. Additionally, EDS and XRD results indicate the presence of oxide phases, which suggests the dielectric reacted with the molten debris during particle formation.

75 FR 16719 - Agricultural Water Enhancement Program

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-02

... DEPARTMENT OF AGRICULTURE Commodity Credit Corporation Agricultural Water Enhancement Program... Energy Act of 2008 (2008 Act) established the Agricultural Water Enhancement Program (AWEP) by amending... to implement agricultural water enhancement activities on agricultural land for the purposes of...

Spinoff 2009

NASA Technical Reports Server (NTRS)

2009-01-01

Topics covered include: Image-Capture Devices Extend Medicine's Reach; Medical Devices Assess, Treat Balance Disorders; NASA Bioreactors Advance Disease Treatments; Robotics Algorithms Provide Nutritional Guidelines; "Anti-Gravity" Treadmills Speed Rehabilitation; Crew Management Processes Revitalize Patient Care; Hubble Systems Optimize Hospital Schedules; Web-based Programs Assess Cognitive Fitness; Electrolyte Concentrates Treat Dehydration; Tools Lighten Designs, Maintain Structural Integrity; Insulating Foams Save Money, Increase Safety; Polyimide Resins Resist Extreme Temperatures; Sensors Locate Radio Interference; Surface Operations Systems Improve Airport Efficiency; Nontoxic Resins Advance Aerospace Manufacturing; Sensors Provide Early Warning of Biological Threats; Robot Saves Soldier's Lives Overseas (MarcBot); Apollo-Era Life Raft Saves Hundreds of Sailors; Circuits Enhance Scientific Instruments and Safety Devices; Tough Textiles Protect Payloads and Public Safety Officers; Forecasting Tools Point to Fishing Hotspots; Air Purifiers Eliminate Pathogens, Preserve Food; Fabrics Protect Sensitive Skin from UV Rays; Phase Change Fabrics Control Temperature; Tiny Devices Project Sharp, Colorful Images; Star-Mapping Tools Enable Tracking of Endangered Animals; Nanofiber Filters Eliminate Contaminants; Modeling Innovations Advance Wind Energy Industry; Thermal Insulation Strips Conserve Energy; Satellite Respondent Buoys Identify Ocean Debris; Mobile Instruments Measure Atmospheric Pollutants; Cloud Imagers Offer New Details on Earth's Health; Antennas Lower Cost of Satellite Access; Feature Detection Systems Enhance Satellite Imagery; Chlorophyll Meters Aid Plant Nutrient Management; Telemetry Boards Interpret Rocket, Airplane Engine Data; Programs Automate Complex Operations Monitoring; Software Tools Streamline Project Management; Modeling Languages Refine Vehicle Design; Radio Relays Improve Wireless Products; Advanced Sensors Boost Optical Communication, Imaging; Tensile Fabrics Enhance Architecture Around the World; Robust Light Filters Support Powerful Imaging Devices; Thermoelectric Devices Cool, Power Electronics; Innovative Tools Advance Revolutionary Weld Technique; Methods Reduce Cost, Enhance Quality of Nanotubes; Gauging Systems Monitor Cryogenic Liquids; Voltage Sensors Monitor Harmful Static; and Compact Instruments Measure Heat Potential.

A Glossy Simultaneous Contrast: Conjoint Measurements of Gloss and Lightness

PubMed Central

Mamassian, Pascal

2017-01-01

Interactions between the albedo and the gloss on a surface are commonplace. Darker surfaces are perceived glossier (contrast gloss) than lighter surfaces and darker backgrounds can enhance perceived lightness of surfaces. We used maximum likelihood conjoint measurements to simultaneously quantify the strength of those effects. We quantified the extent to which albedo can influence perceived gloss and physical gloss can influence perceived lightness. We modeled the contribution of lightness and gloss and found that increasing lightness reduced perceived gloss by about 32% whereas gloss had a much weaker influence on perceived lightness of about 12%. Moreover, we also investigated how different backgrounds contribute to the perception of lightness and gloss of a surface placed in front. We found that a glossy background reduces slightly perceived lightness of the center and simultaneously enhances its perceived gloss. Lighter backgrounds reduce perceived gloss and perceived lightness. Conjoint measurements lead us to a better understanding of the contextual effects in gloss and lightness perception. Not only do we confirm the importance of contrast in gloss perception and the reduction of the simultaneous contrast with glossy backgrounds, but we also quantify precisely the strength of those effects. PMID:28203352

Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

PubMed

Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

2014-01-01

Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly boosting the photocatalytic activity for hydrogen production under UV-vis light.

Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays

NASA Astrophysics Data System (ADS)

Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

2016-05-01

The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion.

Light Coupling and Trapping in Ultrathin Cu(In,Ga)Se2 Solar Cells Using Dielectric Scattering Patterns.

PubMed

van Lare, Claire; Yin, Guanchao; Polman, Albert; Schmid, Martina

2015-10-27

We experimentally demonstrate photocurrent enhancement in ultrathin Cu(In,Ga)Se2 (CIGSe) solar cells with absorber layers of 460 nm by nanoscale dielectric light scattering patterns printed by substrate conformal imprint lithography. We show that patterning the front side of the device with TiO2 nanoparticle arrays results in a small photocurrent enhancement in almost the entire 400-1200 nm spectral range due to enhanced light coupling into the cell. Three-dimensional finite-difference time-domain simulations are in good agreement with external quantum efficiency measurements. Patterning the Mo/CIGSe back interface using SiO2 nanoparticles leads to strongly enhanced light trapping, increasing the efficiency from 11.1% for a flat to 12.3% for a patterned cell. Simulations show that optimizing the array geometry could further improve light trapping. Including nanoparticles at the Mo/CIGSe interface leads to substantially reduced parasitic absorption in the Mo back contact. Parasitic absorption in the back contact can be further reduced by fabricating CIGSe cells on top of a SiO2-patterned In2O3:Sn (ITO) back contact. Simulations show that these semitransparent cells have similar spectrally averaged reflection and absorption in the CIGSe active layer as a Mo-based patterned cell, demonstrating that the absorption losses in the Mo can be partially turned into transmission through the semitransparent geometry.

Delivery of vincristine sulfate-conjugated gold nanoparticles using liposomes: a light-responsive nanocarrier with enhanced antitumor efficiency

PubMed Central

Liu, Ying; He, Man; Niu, Mengmeng; Zhao, Yiqing; Zhu, Yuanzhang; Li, Zhenhua; Feng, Nianping

2015-01-01

Rapid drug release at the specific site of action is still a challenge for antitumor therapy. Development of stimuli-responsive hybrid nanocarriers provides a promising strategy to enhance therapeutic effects by combining the unique features of each component. The present study explored the use of drug–gold nanoparticle conjugates incorporated into liposomes to enhance antitumor efficiency. A model drug, vincristine sulfate, was physically conjugated with gold nanoparticles and verified by UV-visible and fourier transform infrared spectroscopy, and differential scanning calorimetry. The conjugates were incorporated into liposomes by film dispersion to yield nanoparticles (113.4 nm) with light-responsive release properties, as shown by in vitro release studies. Intracellular uptake and distribution was studied in HeLa cells using transmission electron microscopy and confocal laser scanning microscopy. This demonstrated liposome internalization and localization in endosomal–lysosomal vesicles. Fluorescence intensity increased in cells exposed to UV light, indicating that this stimulated intracellular drug release; this finding was confirmed by quantitative analyses using flow cytometry. Antitumor efficacy was evaluated in HeLa cells, both in culture and in implants in vivo in nude mice. HeLa cell viability assays showed that light exposure enhanced liposome cytotoxicity and induction of apoptosis. Furthermore, treatment with the prepared liposomes coupled with UV light exposure produced greater antitumor effects in nude mice and reduced side effects, as compared with free vincristine sulfate. PMID:25960649

Smart pH-responsive upconversion nanoparticles for enhanced tumor cellular internalization and near-infrared light-triggered photodynamic therapy.

PubMed

Wang, Sheng; Zhang, Lei; Dong, Chunhong; Su, Lin; Wang, Hanjie; Chang, Jin

2015-01-01

A smart pH-responsive photodynamic therapy system based on upconversion nanoparticle loaded PEG coated polymeric lipid vesicles (RB-UPPLVs) was designed and prepared. These RB-UPPLVs which are promising agents for deep cancer photodynamic therapy applications can achieve enhanced tumor cellular internalization and near-infrared light-triggered photodynamic therapy.

Dark Skies Preservation through Responsible Lighting: the IYL2015 Quality Lighting Kit

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2015-01-01

Poor quality lighting not only impedes astronomy research, but creates safety issues, affects human circadian sensitivities, disrupts ecosystems, and wastes more than a few billion dollars/year of energy in the USA alone. The United Nations-sanctioned the International Year of Light in 2015 (IYL2015) is providing an opportunity to increase public awareness of dark skies preservation, quality lighting and energy conservation. The Education and Public Outreach (EPO) group at the National Optical Astronomy Observatory (NOAO) has received a small grant through the International Astronomical Union (IAU) to produce official 'Quality Lighting Teaching Kits' for the IYL2015 cornerstone theme, 'Cosmic Light'. These kits will emphasize the use of proper optical design in achieving quality lighting that promotes both energy efficiency and energy conservation of an endangered natural resource, our dark skies. The concepts and practice of 'quality lighting' will be explored through demonstrations, hands-on/minds-on activities, formative assessment probes, and engineering design projects that explore basic principles of optics and the physics of light. The impact of the kits will be amplified by providing professional development using tutorial videos created at NOAO and conducting question and answer sessions via Google+ Hangouts for the outreach volunteers. The quality lighting education program will leverage NOAO EPO's work in the last ten years on lighting and optics education (e.g., the IAU 'Dark Skies Africa', APS 'Dark Skies Yuma' and 'Hands-On Optics' programs). NOAO's partners are CIE (International Commission on Illumination), IDA (International Dark-Sky Association) and SPIE (International Society for Optics and Photonics), as well as the IAU Office of Astronomy for Development, Galileo Teacher Training Program, Universe Awareness, and Global Hands-on Universe. Their networks will disseminate the program and kits to formal and informal audiences worldwide. The impact sought is a change in knowledge, attitude, and behavior in each community by learning how to light responsibly, improving the quality of life in 'illuminating' ways.

Photosensitivity enhancement of PLZT ceramics by positive ion implantation

DOEpatents

Land, Cecil E.; Peercy, Paul S.

1983-01-01

The photosensitivity of lead lanthanum zirconate titanate (PLZT) ceramic material used in high resolution, high contrast, and non-volatile photoferroelectric image storage and display devices is enhanced significantly by positive ion implantation of the PLZT near its surface. Implanted ions include H.sup.+, He.sup.+, Ne.sup.+, Ar.sup.+, as well as chemically reactive ions from Fe, Cr, and Al. The positive ion implantation advantageously serves to shift the absorption characteristics of the PLZT material from near-UV light to visible light. As a result, photosensitivity enhancement is such that the positive ion implanted PLZT plate is sensitive even to sunlight and conventional room lighting, such as fluorescent and incandescent light sources. The method disclosed includes exposing the PLZT plate to the positive ions at sufficient density, from 1.times.10.sup.12 to 1.times.10.sup.17, and with sufficient energy, from 100 to 500 KeV, to provide photosensitivity enhancement. The PLZT material may have a lanthanum content ranging from 5 to 10%, a lead zirconate content of 62 to 70 mole %, and a lead titanate content of 38 to 30%. The ions are implanted at a depth of 0.1 to 2 microns below the surface of the PLZT plate.

Resonant silicon nanoparticles for enhancement of light absorption and photoluminescence from hybrid perovskite films and metasurfaces.

PubMed

Tiguntseva, E; Chebykin, A; Ishteev, A; Haroldson, R; Balachandran, B; Ushakova, E; Komissarenko, F; Wang, H; Milichko, V; Tsypkin, A; Zuev, D; Hu, W; Makarov, S; Zakhidov, A

2017-08-31

Recently, hybrid halide perovskites have emerged as one of the most promising types of materials for thin-film photovoltaic and light-emitting devices because of their low-cost and potential for high efficiency. Further boosting their performance without detrimentally increasing the complexity of the architecture is critically important for commercialization. Despite a number of plasmonic nanoparticle based designs having been proposed for solar cell improvement, inherent optical losses of the nanoparticles reduce photoluminescence from perovskites. Here we use low-loss high-refractive-index dielectric (silicon) nanoparticles for improving the optical properties of organo-metallic perovskite (MAPbI 3 ) films and metasurfaces to achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally a 50% enhancement of photoluminescence intensity from a perovskite layer with silicon nanoparticles and 200% enhancement for a nanoimprinted metasurface with silicon nanoparticles on top. Strong increase in light absorption is also demonstrated and described by theoretical calculations. Since both silicon nanoparticle fabrication/deposition and metasurface nanoimprinting techniques are low-cost, we believe that the developed all-dielectric approach paves the way to novel scalable and highly effective designs of perovskite based metadevices.

Enhancement of Light Absorption in Silicon Nanowire Photovoltaic Devices with Dielectric and Metallic Grating Structures.

PubMed

Park, Jin-Sung; Kim, Kyoung-Ho; Hwang, Min-Soo; Zhang, Xing; Lee, Jung Min; Kim, Jungkil; Song, Kyung-Deok; No, You-Shin; Jeong, Kwang-Yong; Cahoon, James F; Kim, Sun-Kyung; Park, Hong-Gyu

2017-12-13

We report the enhancement of light absorption in Si nanowire photovoltaic devices with one-dimensional dielectric or metallic gratings that are fabricated by a damage-free, precisely aligning, polymer-assisted transfer method. Incorporation of a Si 3 N 4 grating with a Si nanowire effectively enhances the photocurrents for transverse-electric polarized light. The wavelength at which a maximum photocurrent is generated is readily tuned by adjusting the grating pitch. Moreover, the electrical properties of the nanowire devices are preserved before and after transferring the Si 3 N 4 gratings onto Si nanowires, ensuring that the quality of pristine nanowires is not degraded during the transfer. Furthermore, we demonstrate Si nanowire photovoltaic devices with Ag gratings using the same transfer method. Measurements on the fabricated devices reveal approximately 27.1% enhancement in light absorption compared to that of the same devices without the Ag gratings without any degradation of electrical properties. We believe that our polymer-assisted transfer method is not limited to the fabrication of grating-incorporated nanowire photovoltaic devices but can also be generically applied for the implementation of complex nanoscale structures toward the development of multifunctional optoelectronic devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simmons, M.; McKinstry, C.; Cook, C.

Since 1995, the Confederated Tribes of the Colville Reservation (Colville Confederated Tribes) have managed the Chief Joseph Kokanee Enhancement Project as part of the Northwest Power Planning Council (NWPPC) Fish and Wildlife Program. Project objectives have focused on understanding natural production of kokanee (a land-locked sockeye salmon) and other fish stocks in the area above Grand Coulee and Chief Joseph Dams on the Columbia River. A 42-month investigation from 1996 to 1999 determined that from 211,685 to 576,676 fish were entrained annually at Grand Coulee Dam. Analysis of the entrainment data found that 85% of the total entrainment occurred atmore » the dam's third powerplant. These numbers represent a significant loss to the tribal fisheries upstream of the dam. In response to a suggestion by the NWPPC Independent Scientific Review Panel, the scope of work for the Chief Joseph Kokanee Enhancement Project was expanded to include a multiyear pilot test of a strobe light system to help mitigate fish entrainment. This report details the work conducted during the third year of the strobe light study by researchers of the Colville Confederated Tribes in collaboration with the Pacific Northwest National Laboratory. The objective of the study is to determine the efficacy of a prototype strobe light system to elicit a negative phototactic response in kokanee and rainbow trout under field conditions. The prototype system consists of six strobe lights affixed to an aluminum frame suspended 15 m vertically underwater from a barge secured in the center of the entrance to the third powerplant forebay. The lights, controlled by a computer, illuminate a region directly upstream of the barge. The 2003 study period extended from June 16 through August 1. Three light treatments were used: all six lights on for 24 hours, all lights off for 24 hours, and three of six lights cycled on and off every hour for 24 hours. These three treatment conditions were assigned randomly within a 3-day block throughout the study period. Hydroacoustic technology was used to evaluate the effectiveness of the strobe lights in eliciting a negative phototactic response in fish. The hydroacoustic system in 2003 comprised seven splitbeam transducers arrayed in front of the strobe lights, two multibeam transducers behind the lights, and a mobile splitbeam system. The seven splitbeam transducers were deployed so they tracked fish entering and within the region illuminated by the strobe lights. These transducers were spaced approximately 4 m apart on an aluminum frame floating upstream of the barge and looked vertically downward. The multibeam transducers monitored the distribution of fish directly behind and to both sides of the lights, while the mobile splitbeam system looked at the distribution of fish within the third powerplant forebay. To augment the hydroacoustic data, additional studies were conducted. The hydrodynamic characteristics of the third powerplant forebay were measured, and acoustically tagged juvenile kokanee were released upstream of the strobe lights and tracked within the forebay and downstream of the dam. Analysis of the effect of strobe lights on kokanee and rainbow trout focused on the number of fish detected in each of the areas covered by one of the downlooking transducers, the timing of fish arrivals after the status of the strobe lights changed, fish swimming effort (detected velocity minus flow velocity), and fish swimming direction. Water velocity measurements were used to determine fish swimming effort. The tracking of tagged kokanee provided data on fish movements into and out of the third powerplant forebay, including entrainment.« less

Too Hot for Photon-Assisted Transport: Hot-Electrons Dominate Conductance Enhancement in Illuminated Single-Molecule Junctions.

PubMed

Fung, E-Dean; Adak, Olgun; Lovat, Giacomo; Scarabelli, Diego; Venkataraman, Latha

2017-02-08

We investigate light-induced conductance enhancement in single-molecule junctions via photon-assisted transport and hot-electron transport. Using 4,4'-bipyridine bound to Au electrodes as a prototypical single-molecule junction, we report a 20-40% enhancement in conductance under illumination with 980 nm wavelength radiation. We probe the effects of subtle changes in the transmission function on light-enhanced current and show that discrete variations in the binding geometry result in a 10% change in enhancement. Importantly, we prove theoretically that the steady-state behavior of photon-assisted transport and hot-electron transport is identical but that hot-electron transport is the dominant mechanism for optically induced conductance enhancement in single-molecule junctions when the wavelength used is absorbed by the electrodes and the hot-electron relaxation time is long. We confirm this experimentally by performing polarization-dependent conductance measurements of illuminated 4,4'-bipyridine junctions. Finally, we perform lock-in type measurements of optical current and conclude that currents due to laser-induced thermal expansion mask optical currents. This work provides a robust experimental framework for studying mechanisms of light-enhanced transport in single-molecule junctions and offers tools for tuning the performance of organic optoelectronic devices by analyzing detailed transport properties of the molecules involved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yeping, E-mail: ypli@ujs.edu.cn; Huang, Liying; Xu, Jingbo

Highlights: • Novel MoO{sub 3}–C{sub 3}N{sub 4} composite was prepared by a mixing-calcination method. • The MoO{sub 3}–C{sub 3}N{sub 4} composite shows remarkably enhanced absorption of visible light. • The MoO{sub 3}–C{sub 3}N{sub 4} composite shows superior visible-light photocatalytic activity. - Abstract: Composite photocatalyst of blue MoO{sub 3}/g-C{sub 3}N{sub 4} (denoted as MoO{sub 3}–C{sub 3}N{sub 4}) was prepared by a simple mixing-calcination method. The obtained MoO{sub 3}–C{sub 3}N{sub 4} composite contains a low amount of molybdenum blue and shows remarkably enhanced absorption of visible light and high efficiency for the degradation of methylene blue dye (MB) under visible light. Themore » enhancement of visible light photocatalytic activity in MoO{sub 3}–C{sub 3}N{sub 4} is attributed to the synergetic effect: (i) the strong and wide absorption of visible light, (ii) the high separation and easy transfer of photogenerated electron–hole pairs at the heterojunction interfaces derived from the match of band position between the g-C{sub 3}N{sub 4} and MoO{sub 3}.« less

Improvement of light extraction of LYSO scintillator by using a combination of self-assembly of nanospheres and atomic layer deposition.

PubMed

Zhu, Zhichao; Liu, Bo; Zhang, Haifeng; Ren, Weina; Cheng, Chuanwei; Wu, Shuang; Gu, Mu; Chen, Hong

2015-03-23

The self-assembled monolayer periodic array of polystyrene spheres conformally coated with TiO₂ layer using atomic layer deposition is designed to obtain a further enhancement of light extraction for LYSO scintillator. The maximum enhancement is 149% for the sample with polystyrene spheres conformally coated with TiO₂ layer, while the enhancement is only 76% for the sample with only polystyrene spheres. Such further enhancement could be contributed from the additional modes forming by TiO₂ layer due to its high refractive index, which can be approved by the simulation of electric field distribution. The experimental results are agreement with the simulated results. Furthermore, the prepared structured layer exhibits an excellent combination with the surface of scintillator, which is in favor of the practical application. Therefore, it is safely concluded that the combination of self-assembly method and atomic layer deposition is a promising approach to obtain a significant enhancement of light extraction for a large area. This method can be extended to many other luminescent materials and devices.

Enhancement of polarizabilities of cylinders with cylinder-slab resonances

PubMed Central

Xiao, Meng; Huang, Xueqin; Liu, H.; Chan, C. T.

2015-01-01

If an object is very small in size compared with the wavelength of light, it does not scatter light efficiently. It is hence difficult to detect a very small object with light. We show using analytic theory as well as full wave numerical calculation that the effective polarizability of a small cylinder can be greatly enhanced by coupling it with a superlens type metamaterial slab. This kind of enhancement is not due to the individual resonance effect of the metamaterial slab, nor due to that of the object, but is caused by a collective resonant mode between the cylinder and the slab. We show that this type of particle-slab resonance which makes a small two-dimensional object much “brighter” is actually closely related to the reverse effect known in the literature as “cloaking by anomalous resonance” which can make a small cylinder undetectable. We also show that the enhancement of polarizability can lead to strongly enhanced electromagnetic forces that can be attractive or repulsive, depending on the material properties of the cylinder. PMID:25641391

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

PubMed Central

Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

2017-01-01

In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results. PMID:28374856

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns.

PubMed

Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

2017-04-04

In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results.

Efficiency enhancement of blue light emitting diodes by eliminating V-defects from InGaN/GaN multiple quantum well structures through GaN capping layer control

NASA Astrophysics Data System (ADS)

Tsai, Sheng-Chieh; Li, Ming-Jui; Fang, Hsin-Chiao; Tu, Chia-Hao; Liu, Chuan-Pu

2018-05-01

A facile method for fabricating blue light-emitting diodes (B-LEDs) with small embedded quantum dots (QDs) and enhanced light emission is demonstrated by tuning the temperature of the growing GaN capping layer to eliminate V-defects. As the growth temperature increases from 770 °C to 840 °C, not only does the density of the V-defects reduce from 4.12 ∗ 108 #/cm2 nm to zero on a smooth surface, but the QDs also get smaller. Therefore, the growth mechanism of smaller QDs assisted by elimination of V-defects is discussed. Photoluminescence and electroluminescence results show that smaller embedded QDs can improve recombination efficiency, and thus achieve higher peak intensity with smaller peak broadening. Accordingly, the external quantum efficiency of the B-LEDs with smaller QDs is enhanced, leading to a 6.8% increase in light output power in lamp-form package LEDs.

Hierarchical assembly of AgCl@Sn-TiO2 microspheres with enhanced visible light photocatalytic performance

NASA Astrophysics Data System (ADS)

Ganeshraja, Ayyakannu Sundaram; Zhu, Kaixin; Nomura, Kiyoshi; Wang, Junhu

2018-05-01

The hierarchical silver chloride loaded tin-doped titania (AgCl@Sn-TiO2) microspheres were first time prepared by a hydrothermal method and annealing at different temperatures. The catalyst showed the enhanced visible light photocatalytic activity as compared to the plasmonic photocatalysts of AgCl and Ag/AgCl, and commercial Degussa P25 (TiO2). The improved efficiency is considered to local surface plasmonic resonance (AgCl could reduce to Ag0 during photocatalytic reaction) in enhanced broad band visible light absorption in addition to the characteristics of heterojunction between Sn-TiO2 and AgCl NPs. Moreover, the surface and bulk properties of as-synthesized samples were analyzed by 119Sn Mössbauer spectroscopy. The magnetic property of the bulk was studied as a function of magnetic field with different temperatures. These results signify the clear details of the magnetic and visible light photocatalytic activities of hierarchical AgCl@Sn-TiO2 microspheres.

Graphitic Carbon-Based Nanostructures for Energy and Environmental Applications

NASA Astrophysics Data System (ADS)

Chan, Ka Long Donald

This thesis focuses on the synthesis and characterization of graphitic carbonbased photocatalytic nanostructures for energy and environmental applications. The preparation of carbon- and oxygen-rich graphitic carbon nitride with enhanced photocatalytic hydrogen evolution property was investigated. Composite materials based on graphene quantum dots were also prepared. These composites were used for photocatalytic degradation of organic pollutants and photoelectrocatalytic disinfection. The first part of this thesis describes a facile method for the preparation of carbon- and oxygen-rich graphitic carbon nitride by thermal condensation. Incorporation of carbon and oxygen enhanced the photoresponse of carbon nitride in the visible-light region. After exfoliation, the product was c.a. 45 times more active than bulk graphitic carbon nitride in photocatalytic hydrogen evolution under visible-light irradiation. In the second part, a simple approach to enhance the photocatalytic activity of red phosphorus was developed. Mechanical ball milling was applied to reduce the size of red phosphorus and to deposit graphene quantum dots (GQDs) onto red phosphorus. The product exhibited high visible-light-driven photocatalytic performance in the photodegradation of Rhodamine B. The incorporation of GQDs in titanium dioxide could also extend the absorption spectrum of TiO2 into the visible-light range. The third part of this thesis reports on the fabrication of a visible-light-driven composite photocatalyst of TiO2 nanotube arrays (TNAs) and GQDs. Carboxyl-containing GQDs were covalently coupled to amine-modified TNAs. The product exhibited enhanced photocurrent and high photoelectrocatalytic performance in the inactivation of E. coli under visible-light irradiation. The role of various reactive species in the photoelectrocatalytic process was investigated.

Cavity-Enhanced Raman Spectroscopy for Food Chain Management

PubMed Central

Sandfort, Vincenz; Goldschmidt, Jens; Wöllenstein, Jürgen

2018-01-01

Comprehensive food chain management requires the monitoring of many parameters including temperature, humidity, and multiple gases. The latter is highly challenging because no low-cost technology for the simultaneous chemical analysis of multiple gaseous components currently exists. This contribution proposes the use of cavity enhanced Raman spectroscopy to enable online monitoring of all relevant components using a single laser source. A laboratory scale setup is presented and characterized in detail. Power enhancement of the pump light is achieved in an optical resonator with a Finesse exceeding 2500. A simulation for the light scattering behavior shows the influence of polarization on the spatial distribution of the Raman scattered light. The setup is also used to measure three relevant showcase gases to demonstrate the feasibility of the approach, including carbon dioxide, oxygen and ethene. PMID:29495501

Enhanced light absorption in an ultrathin silicon solar cell utilizing plasmonic nanostructures

NASA Astrophysics Data System (ADS)

Xiao, Sanshui; Mortensen, Niels A.

2012-10-01

Nowadays, bringing photovoltaics to the market is mainly limited by high cost of electricity produced by the photovoltaic solar cell. Thin-film photovoltaics offers the potential for a significant cost reduction compared to traditional photovoltaics. However, the performance of thin-film solar cells is generally limited by poor light absorption. We propose an ultrathin-film silicon solar cell configuration based on SOI structure, where the light absorption is enhanced by use of plasmonic nanostructures. By placing a one-dimensional plasmonic nanograting on the bottom of the solar cell, the generated photocurrent for a 200 nm-thickness crystalline silicon solar cell can be enhanced by 90% in the considered wavelength range. These results are paving a promising way for the realization of high-efficiency thin-film solar cells.

Effects of Mg-doped AlN/AlGaN superlattices on properties of p-GaN contact layer and performance of deep ultraviolet light emitting diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al tahtamouni, T. M., E-mail: talal@yu.edu.jo; Lin, J. Y.; Jiang, H. X.

2014-04-15

Mg-doped AlN/AlGaN superlattice (Mg-SL) and Mg-doped AlGaN epilayers have been investigated in the 284 nm deep ultraviolet (DUV) light emitting diodes (LEDs) as electron blocking layers. It was found that the use of Mg-SL improved the material quality of the p-GaN contact layer, as evidenced in the decreased density of surface pits and improved surface morphology and crystalline quality. The performance of the DUV LEDs fabricated using Mg-SL was significantly improved, as manifested by enhanced light intensity and output power, and reduced turn-on voltage. The improved performance is attributed to the enhanced blocking of electron overflow, and enhanced hole injection.

The International Year of Light 2015 and its impact on educational activities

NASA Astrophysics Data System (ADS)

Curticapean, Dan; Vauderwange, Oliver; Wozniak, Peter; Mandal, Avikarsha

2016-09-01

The International Year of Light and Light-Based Technologies 2015 (IYL 2015) was celebrated around the world. Worldwide activities were organized to highlight the impact of optics and photonics on life, science, economics, arts and culture, and also in education. With most of our activities at Offenburg University of Applied Sciences (Offenburg/Germany), we reached our own students and the general population of our region: - University for Children: "The Magic of Light" winter lecture program and "Across the Universe with Relativity and Quantum Theory" summer lecture program - "Students Meet Scientists" - "A Century of General Relativity Theory" lecture program Nevertheless, with some of our activities we also engaged a worldwide audience: - IYL 2015 art poster collection (Magic of Light and No Football, Just Photonics) - Smart Interactive Projection - Twitter Wall - "Invisible Light" - Live broadcasting of the total lunar eclipse - Film Festival Merida Mexico The authors will highlight recent activities at our university dedicated to promote, celebrate, and create a legacy for the IYL 2015.

Strobe Traffic Lights Warn of Approaching Emergency Vehicles

NASA Technical Reports Server (NTRS)

Bachelder, Aaron

2004-01-01

Strobe-enhanced traffic signals have been developed to aid in the preemption of road intersections for emergency vehicles. The strobe-enhanced traffic signals can be incorporated into both new and pre-existing traffic-control systems in which the traffic-signal heads are of a relatively new type based on arrays of light-emitting diodes (LEDs). The strobe-enhanced traffic signals offer a less expensive, less complex alternative to a recently developed system of LED-based warning signs placed next to traffic signals. Because of its visual complexity, the combination of traffic signals and warning signs is potentially confusing to motorists. The strobe-enhanced traffic signals present less visual clutter. In a given traffic-signal head, the strobe-enhanced traffic signal is embedded in the red LED array of the stop signal. Two strobe LED strips one horizontal and one vertical are made capable of operating separately from the rest of the red LED matrix. When no emergency vehicle is approaching, the red LED array functions as a normal stop signal: all the red LEDs are turned on and off together. When the intersection is to be preempted for an approaching emergency vehicle, only the LEDs in one of the strobe strips are lit, and are turned on in a sequence that indicates the direction of approach. For example (see figure), if an emergency vehicle approaches from the right, the strobe LEDs are lit in a sequence moving from right to left. Important to the success of strobe-enhanced traffic signals is conformance to city ordinances and close relation to pre-existing traffic standards. For instance, one key restriction is that new icons must not include arrows, so that motorists will not confuse new icons with conventional arrows that indicate allowed directions of movement. It is also critical that new displays like strobe-enhanced traffic signals be similar to displays used in traffic-control systems in large cities. For example, Charleston, South Carolina uses horizontal strobes on red traffic lights to alert motorists and thereby help motorists not to miss red lights. The one significant potential disadvantage of strobe-enhanced traffic lights is initial unfamiliarity on the part of motorists.

Periodic molybdenum disc array for light trapping in amorphous silicon layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiwei; Deng, Changkai; Shanghai Advanced Research Institute, Chinese Academy of Sciences, 99 Haike Road, Shanghai, 201210 China

2016-05-15

We demonstrate the light trapping effect in amorphous silicon (a-Si:H) layer by inserting a layer of periodic molybdenum disc array (MDA) between the a-Si:H layer and the quartz substrate, which forms a three-layer structure of Si/MDA/SiO{sub 2}. The MDA layer was fabricated by a new cost-effective method based on nano-imprint technology. Further light absorption enhancement was realized through altering the topography of MDA by annealing it at 700°C. The mechanism of light absorption enhancement in a-Si:H interfaced with MDA was analyzed, and the electric field distribution and light absorption curve of the different layers in the Si/MDA structure under lightmore » illumination of different wavelengths were simulated by employing numerical finite difference time domain (FDTD) solutions.« less

An ion exchange strategy to BiOI/CH3COO(BiO) heterojunction with enhanced visible-light photocatalytic activity

NASA Astrophysics Data System (ADS)

Han, Qiaofeng; Yang, Zhen; Wang, Li; Shen, Zichen; Wang, Xin; Zhu, Junwu; Jiang, Xiaohong

2017-05-01

It is very significant to develop CH3COO(BiO) (denoted as BiOAc) based photocatalysts for the removal of pollutants due to its non-toxicity and availability. We previously reported that BiOAc exhibited excellent photocatalytic activity for rhodamine B (RhB) degradation under UV light irradiation. Herein, by an ion exchange approach, BiOI/BiOAc heterojunction could be easily obtained. The as-prepared heterojunction possessed enhanced photodegradation activity for multiple dyes including RhB and methyl orange (MO) under visible light illumination in comparison with individual materials. Good visible-light photocatalytic activity of the heterojunction could be attributed to the increased visible light response, effective charge transfer from the modified band position and close interfacial contact due to partial ion exchange method.

Enhanced light out-coupling efficiency of organic light-emitting diodes with an extremely low haze by plasma treated nanoscale corrugation.

PubMed

Hwang, Ju Hyun; Lee, Hyun Jun; Shim, Yong Sub; Park, Cheol Hwee; Jung, Sun-Gyu; Kim, Kyu Nyun; Park, Young Wook; Ju, Byeong-Kwon

2015-02-14

Extremely low-haze light extraction from organic light-emitting diodes (OLEDs) was achieved by utilizing nanoscale corrugation, which was simply fabricated with plasma treatment and sonication. The haze of the nanoscale corrugation for light extraction (NCLE) corresponds to 0.21% for visible wavelengths, which is comparable to that of bare glass. The OLEDs with NCLE showed enhancements of 34.19% in current efficiency and 35.75% in power efficiency. Furthermore, the OLEDs with NCLE exhibited angle-stable electroluminescence (EL) spectra for different viewing angles, with no change in the full width at half maximum (FWHM) and peak wavelength. The flexibility of the polymer used for the NCLE and plasma treatment process indicates that the NCLE can be applied to large and flexible OLED displays.

Enhancing light-harvesting power with coherent vibrational interactions: A quantum heat engine picture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Killoran, N.; Huelga, S. F.; Plenio, M. B.

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system’s power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principlemore » and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle’s relevance in parameter regimes connected to natural light-harvesting structures.« less

Quantum dots as enhancers of the efficacy of bacterial lethal photosensitization

NASA Astrophysics Data System (ADS)

Narband, N.; Mubarak, M.; Ready, D.; Parkin, I. P.; Nair, S. P.; Green, M. A.; Beeby, A.; Wilson, M.

2008-11-01

Because of the increasing resistance of bacteria to antibiotics there is considerable interest in light-activated antimicrobial agents (LAAAs) as alternatives to antibiotics for treating localized infections. The purpose of this study was to determine whether CdSe/ZnS quantum dots (QD) could enhance the antibacterial activity of the LAAA, toluidine blue O (TBO). Suspensions of Staphylococcus aureus and Streptococcus pyogenes were exposed to white light (3600 lux) and TBO (absorbance maximum = 630 nm) in the presence and absence of 25 nm diameter QD (emission maximum = 627 nm). When the TBO:QD ratio was 2667:1, killing of Staph. aureus was enhanced by 1.72log10 units. In the case of Strep. pyogenes, an enhanced kill of 1.55log10 units was achieved using TBO and QD in the ratio 267:1. Singlet oxygen and fluorescence measurements showed that QD suppress the formation of singlet oxygen from TBO and that QD fluorescence is significantly quenched in the presence of TBO (70-90%). Enhanced killing appears to be attributable to a non-Förster resonance energy transfer mechanism, whereby the QD converts part of the incident light to the absorption maximum for TBO; hence more light energy is harvested, resulting in increased concentrations of bactericidal radicals. QD may, therefore, be useful in improving the efficacy of antimicrobial photodynamic therapy.

Laser Light Scattering with Multiple Scattering Suppression Used to Measure Particle Sizes

NASA Technical Reports Server (NTRS)

Meyer, William V.; Tin, Padetha; Lock, James A.; Cannell, David S.; Smart, Anthony E.; Taylor, Thomas W.

1999-01-01

Laser light scattering is the technique of choice for noninvasively sizing particles in a fluid. The members of the Advanced Technology Development (ATD) project in laser light scattering at the NASA Lewis Research Center have invented, tested, and recently enhanced a simple and elegant way to extend the concentration range of this standard laboratory particle-sizing technique by several orders of magnitude. With this technique, particles from 3 nm to 3 mm can be measured in a solution. Recently, laser light scattering evolved to successfully size particles in both clear solutions and concentrated milky-white solutions. The enhanced technique uses the property of light that causes it to form tall interference patterns at right angles to the scattering plane (perpendicular to the laser beam) when it is scattered from a narrow laser beam. Such multiple-scattered light forms a broad fuzzy halo around the focused beam, which, in turn, forms short interference patterns. By placing two fiber optics on top of each other and perpendicular to the laser beam (see the drawing), and then cross-correlating the signals they produce, only the tall interference patterns formed by singly scattered light are detected. To restate this, unless the two fiber optics see the same interference pattern, the scattered light is not incorporated into the signal. With this technique, only singly scattered light is seen (multiple-scattered light is rejected) because only singly scattered light has an interference pattern tall enough to span both of the fiber-optic pickups. This technique is simple to use, easy to align, and works at any angle. Placing a vertical slit in front of the signal collection fibers enhanced this approach. The slit serves as an optical mask, and it significantly shortens the time needed to collect good data by selectively masking out much of the unwanted light before cross-correlation is applied.

Spotlight on fish: light pollution affects circadian rhythms of European perch but does not cause stress.

PubMed

Brüning, Anika; Hölker, Franz; Franke, Steffen; Preuer, Torsten; Kloas, Werner

2015-04-01

Flora and fauna evolved under natural day and night cycles. However, natural light is now enhanced by artificial light at night, particularly in urban areas. This alteration of natural light environments during the night is hypothesised to alter biological rhythms in fish, by effecting night-time production of the hormone melatonin. Artificial light at night is also expected to increase the stress level of fish, resulting in higher cortisol production. In laboratory experiments, European perch (Perca fluviatilis) were exposed to four different light intensities during the night, 0 lx (control), 1 lx (potential light level in urban waters), 10 lx (typical street lighting at night) and 100 lx. Melatonin and cortisol concentrations were measured from water samples every 3h during a 24 hour period. This study revealed that the nocturnal increase in melatonin production was inhibited even at the lowest light level of 1 lx. However, cortisol levels did not differ between control and treatment illumination levels. We conclude that artificial light at night at very low intensities may disturb biological rhythms in fish since nocturnal light levels around 1 lx are already found in urban waters. However, enhanced stress induction could not be demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

Advanced Computational Thermal Fluid Physics (CTFP) and Its Assessment for Light Water Reactors and Supercritical Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

D.M. McEligot; K. G. Condie; G. E. McCreery

2005-10-01

Background: The ultimate goal of the study is the improvement of predictive methods for safety analyses and design of Generation IV reactor systems such as supercritical water reactors (SCWR) for higher efficiency, improved performance and operation, design simplification, enhanced safety and reduced waste and cost. The objective of this Korean / US / laboratory / university collaboration of coupled fundamental computational and experimental studies is to develop the supporting knowledge needed for improved predictive techniques for use in the technology development of Generation IV reactor concepts and their passive safety systems. The present study emphasizes SCWR concepts in the Generationmore » IV program.« less

Privacy Impact Assessment for the Light-Duty In-Use Vehicle Testing Program Information System

EPA Pesticide Factsheets

EPA's Light-Duty In-Use Vehicle Testing Program Information System contains car owner names, addresses, vehicle identification numbers, etc. The EPA uses this information to recruit and test vehicles for emissions standards compliance.

NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

NASA Technical Reports Server (NTRS)

Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

1996-01-01

The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. Three research areas are being actively investigated, including: (1) Mechanical and environmental degradation mechanisms in advanced light metals, (2) Aerospace materials science, and (3) Mechanics of materials for light aerospace structures.

75 FR 18146 - Wetlands Reserve Enhancement Program

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-09

... DEPARTMENT OF AGRICULTURE Commodity Credit Corporation Wetlands Reserve Enhancement Program AGENCY... assistance will be made available in fiscal year (FY) 2010 for the Wetlands Reserve Enhancement Program (WREP... partners to help enhance conservation outcomes on wetlands and adjacent lands. WREP targets and leverages...

``Dark Skies are a Universal Resource'' Programs Planned for the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, C. E.; Berglund, K.; Bueter, C.; Crelin, B.; Duriscoe, D.; Moore, C.; Gauthier, A.; Gay, P. L.; Foster, T.; Heatherly, S. A.; Maddalena, R.; Mann, T.; Patten, K.; Pompea, S. M.; Sparks, R.; Schaaf, F.; Simmons, M.; Smith, C.; Smith, M.; Tafreshi, B.

2008-11-01

In an effort to help more people appreciate the ongoing loss of a dark night sky for much of the world's population and to raise public knowledge about diverse impacts of excess artificial lighting on local environments, the International Year of Astronomy's Dark Skies Working Group has established six ``Dark Skies'' programs and six ``Dark Skies'' resources. The Dark Skies programs include GLOBE at Night (with Earth Hour), Astronomy Nights in the [National] Parks, Dark Skies Discovery Sites, Quiet Skies, Good Neighbor Lighting, and a digital photography contest. Resources include the light education toolkit, the ``Let There Be Night'' DVD and planetarium program, the 6-minute video, online interactions like Second Life, podcasts, and traveling exhibits. The programs and resources are summarized here, as they were in a poster for the June 2008 ASP/AAS conference. For more information on these programs and resources, visit http://astronomy2009.us/darkskies/.

Real time optical edge enhancement using a Hughes liquid crystal light valve

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin

1989-01-01

The discovery of an edge enhancement effect in using a Hughes CdS liquid crystal light valve (LCLV) is reported. An edge-enhanced version of the input writing image can be directly obtained by operating the LCLV at a lower bias frequency and bias voltage. Experimental conditions in which this edge enhancement effect can be optimized are described. Experimental results show that the SNR of the readout image using this technique is superior to that obtained using high-pass filtering. The repeatability of this effect is confirmed by obtaining an edge enhancement result using two different Hughes LCLVs. The applicability of this effect to improve discrimination capability in optical pattern recognition is addressed. The results show that the Hughes LCLV can be used in both continuous tone and edge-enhancing modes by simply adjusting its bias conditions.

Blue light-promoted rice leaf bending and unrolling are due to up-regulated brassinosteroid biosynthesis genes accompanied by accumulation of castasterone.

PubMed

Asahina, Masashi; Tamaki, Yuji; Sakamoto, Tomoaki; Shibata, Kyomi; Nomura, Takahito; Yokota, Takao

2014-08-01

In this study the relationship between blue light- and brassinosteroid-enhanced leaf lamina bending and unrolling in rice was investigated. Twenty-four hours (h) irradiation with white or blue light increased endogenous brassinosteroid levels, especially those of typhasterol and castasterone, in aerial tissues of rice seedlings. There was an accompanying up-regulation of transcript levels of CYP85A1/OsDWARF, encoding an enzyme catalyzing C-6 oxidation, after 6h under either white or blue light. These effects were not observed in seedlings placed under far-red or red light regimes. It was concluded that blue light up-regulates the levels of several cytochrome P450 enzymes including CYP85A1, thereby promoting the synthesis of castasterone, a biologically active brassinosteroid in rice. Based on these findings, it is considered that blue light-mediated rice leaf bending and unrolling are consequences of the enhanced biosynthesis of endogenous castasterone. In contrast to aerial tissues, brassinosteroid synthesis in roots appeared to be negatively regulated by white, blue and red light but positively controlled by far-red light. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis of hierarchically meso-macroporous TiO2/CdS heterojunction photocatalysts with excellent visible-light photocatalytic activity.

PubMed

Zhao, Haixin; Cui, Shu; Yang, Lan; Li, Guodong; Li, Nan; Li, Xiaotian

2018-02-15

Photocatalysts with a hierarchically porous structure have attracted considerable attention owing to their wide pore size distribution and high surface area, which enhance the efficiency of transporting species to active sites. In this study, hierarchically meso-macroporous TiO 2 photocatalysts decorated with highly dispersed CdS nanoparticles were synthesized via hydrolysis, followed by a hydrothermal treatment. The textural mesopores and interconnected pore framework provided more accessible active sites and efficient mass transport for the photocatalytic process. The light collection efficiency was enhanced because of multiple scattering of incident light in the macropores. Moreover, the formation of a heterojunction between the CdS and TiO 2 nanoparticles extended the photoresponse of TiO 2 to the visible-light range and enhanced the charge separation efficiency. Therefore, the hierarchically meso-macroporous TiO 2 /CdS photocatalysts exhibited excellent photocatalytic activity for the degradation of rhodaming B under visible-light irradiation. Trapping experiments demonstrated that superoxide radicals (O 2 - ) and hydroxyl radicals (OH) were the main active species in photocatalysis. A reasonable photocatalytic mechanism of TiO 2 /CdS heterojunction photocatalysts was also presented. Copyright © 2017 Elsevier Inc. All rights reserved.

Effectively infinite optical path-length created using a simple cubic photonic crystal for extreme light trapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frey, Brian J.; Kuang, Ping; Hsieh, Mei-Li

A 900 nm thick TiO 2 simple cubic photonic crystal with lattice constant 450 nm was fabricated and used to experimentally validate a newly-discovered mechanism for extreme light-bending. Absorption enhancement was observed extending 1–2 orders of magnitude over that of a reference TiO 2 film. Several enhancement peaks in the region from 600–950 nm were identified, which far exceed both the ergodic fundamental limit and the limit based on surface-gratings, with some peaks exceeding 100 times enhancement. These results are attributed to radically sharp refraction where the optical path length approaches infinity due to the Poynting vector lying nearly parallelmore » to the photonic crystal interface. The observed phenomena follow directly from the simple cubic symmetry of the photonic crystal, and can be achieved by integrating the light-trapping architecture into the absorbing volume. These results are not dependent on the material used, and can be applied to any future light trapping applications such as phosphor-converted white light generation, water-splitting, or thin-film solar cells, where increased response in areas of weak absorption is desired.« less

Black TiO2 synthesized via magnesiothermic reduction for enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Wang, Xiangdong; Fu, Rong; Yin, Qianqian; Wu, Han; Guo, Xiaoling; Xu, Ruohan; Zhong, Qianyun

2018-04-01

Utilizing solar energy for hydrogen evolution is a great challenge for its insufficient visible-light power conversion. In this paper, we report a facile magnesiothermic reduction of commercial TiO2 nanoparticles under Ar atmosphere and at 550 °C followed by acid treatment to synthesize reduced black TiO2 powders, which possesses a unique crystalline core-amorphous shell structure composed of disordered surface and oxygen vacancies and shows significantly improved optical absorption in the visible region. The unique core-shell structure and high absorption enable the reduced black TiO2 powders to exhibit enhanced photocatalytic activity, including splitting of water in the presence of Pt as a cocatalyst and degradation of methyl blue (MB) under visible light irradiation. Photocatalytic evaluations indicate that the oxygen vacancies play key roles in the catalytic process. The maximum hydrogen production rates are 16.1 and 163 μmol h-1 g-1 under the full solar wavelength range of light and visible light, respectively. This facile and versatile method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven hydrogen production.

Effectively infinite optical path-length created using a simple cubic photonic crystal for extreme light trapping

DOE PAGES

Frey, Brian J.; Kuang, Ping; Hsieh, Mei-Li; ...

2017-06-23

A 900 nm thick TiO 2 simple cubic photonic crystal with lattice constant 450 nm was fabricated and used to experimentally validate a newly-discovered mechanism for extreme light-bending. Absorption enhancement was observed extending 1–2 orders of magnitude over that of a reference TiO 2 film. Several enhancement peaks in the region from 600–950 nm were identified, which far exceed both the ergodic fundamental limit and the limit based on surface-gratings, with some peaks exceeding 100 times enhancement. These results are attributed to radically sharp refraction where the optical path length approaches infinity due to the Poynting vector lying nearly parallelmore » to the photonic crystal interface. The observed phenomena follow directly from the simple cubic symmetry of the photonic crystal, and can be achieved by integrating the light-trapping architecture into the absorbing volume. These results are not dependent on the material used, and can be applied to any future light trapping applications such as phosphor-converted white light generation, water-splitting, or thin-film solar cells, where increased response in areas of weak absorption is desired.« less

Ocean acidification modulates expression of genes and physiological performance of a marine diatom

NASA Astrophysics Data System (ADS)

Li, Y.; Zhuang, S.; Wu, Y.; Ren, H.; Cheng, F.; Lin, X.; Wang, K.; Beardall, J.; Gao, K.

2015-09-01

Ocean Acidification (OA) is known to affect various aspects of the physiological performance of diatoms, but there is little information on the underlining molecular mechanisms involved. Here, we show that in the model diatom Phaeodactylum tricornutum expression of the genes related to light harvesting, carbon acquisition and carboxylation, nitrite assimilation and ATP synthesis are modulated by OA. Growth and photosynthetic carbon fixation were enhanced by elevated CO2 (1000 μatm) under both constant indoor and fluctuating outdoor light regimes. The genetic expression of nitrite reductase (NiR) was up-regulated by OA regardless of light levels and/or regimes. The transcriptional expression of fucoxanthin chlorophyll a/c protein (lhcf type (FCP)) and mitochondrial ATP synthase (mtATP synthase) genes were also enhanced by OA, but only under high light intensity. OA treatment decreased the expression of β-carbonic anhydrase (β-CA) along with down-regulation of CO2 concentrating mechanisms (CCMs). Additionally, the genes for these proteins (NiR, FCP, mtATP synthase, β-CA) showed diel expressions either under constant indoor light or fluctuating sunlight. Thus, OA enhanced photosynthetic and growth rates by stimulating nitrogen assimilation and indirectly by down-regulating the energy-costly inorganic carbon acquisition process.

The KMOS Cluster Survey (KCS). II. The Effect of Environment on the Structural Properties of Massive Cluster Galaxies at Redshift 1.39 < z < 1.61

NASA Astrophysics Data System (ADS)

Chan, Jeffrey C. C.; Beifiori, Alessandra; Saglia, Roberto P.; Mendel, J. Trevor; Stott, John P.; Bender, Ralf; Galametz, Audrey; Wilman, David J.; Cappellari, Michele; Davies, Roger L.; Houghton, Ryan C. W.; Prichard, Laura J.; Lewis, Ian J.; Sharples, Ray; Wegner, Michael

2018-03-01

We present results on the structural properties of massive passive galaxies in three clusters at 1.39 < z < 1.61 from the KMOS Cluster Survey. We measure light-weighted and mass-weighted sizes from optical and near-infrared Hubble Space Telescope imaging and spatially resolved stellar mass maps. The rest-frame R-band sizes of these galaxies are a factor of ∼2–3 smaller than their local counterparts. The slopes of the relation between the stellar mass and the light-weighted size are consistent with recent studies in clusters and the field. Their mass-weighted sizes are smaller than the rest-frame R-band sizes, with an average mass-weighted to light-weighted size ratio that varies between ∼0.45 and 0.8 among the clusters. We find that the median light-weighted size of the passive galaxies in the two more evolved clusters is ∼24% larger than that for field galaxies, independent of the use of circularized effective radii or semimajor axes. These two clusters also show a smaller size ratio than the less evolved cluster, which we investigate using color gradients to probe the underlying {M}* /{L}{{{H}}160} gradients. The median color gradients are ∇z ‑ H ∼ ‑0.4 mag dex‑1, twice the local value. Using stellar populations models, these gradients are best reproduced by a combination of age and metallicity gradients. Our results favor the minor merger scenario as the dominant process responsible for the observed galaxy properties and the environmental differences at this redshift. The environmental differences support that clusters experience accelerated structural evolution compared to the field, likely via an epoch of enhanced minor merger activity during cluster assembly. Based on observations obtained at the Very Large Telescope (VLT) of the European Southern Observatory (ESO; program IDs: 092.A-0210; 093.A-0051; 094.A-0578; 095.A-0137(A); 096.A-0189(A); 097.A-0332(A)). This work is based on observations made with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO 13687, as well as with the CANDELS Multi-Cycle Treasury Program and the 3D-HST Treasury Program (GO 12177 and 12328).

A Physiological and Psychometric Evaluation of Human Subconscious Visual Response and Its Application in Health Promoting Lighting

NASA Astrophysics Data System (ADS)

Vartanian, Garen V.

Subconscious vision is a recent focus of the vision science community, brought on by the discovery of a previously unknown photoreceptor in the retina dedicated to driving non-image-forming responses, intrinsically photosensitive retinal ganglion cells (ipRGCs). In addition to accepting inputs from rod and cone photoreceptors, ipRGCs contain their own photopigment, melanopsin, and are considered true photoreceptors. ipRGCs drive various non-image-forming photoresponses, including circadian photoentrainment, melatonin suppression, and pupil constriction. In order to understand more about ipRGC function in humans, we studied its sensitivity to light stimuli in the evening and day. First, we measured the sensitivity threshold of melatonin suppression at night. Using a protocol that enhances data precision, we have found the threshold for human melatonin suppression to be two orders of magnitude lower than previously reported. This finding has far-reaching implications since there is mounting evidence that nocturnal activation of the circadian system can be harmful. Paradoxically, ipRGCs are understimulated during the day. Optimizing daytime non-image-forming photostimulation has health benefits, such as increased alertness, faster reaction times, better sleep quality, and treatment of depression. In order to enhance ipRGC excitation, we aimed to circumvent adaptation (i.e. desensitization) of the photoresponse by using flickering instead of steady light. We find that properly timed flickering light enhances pupillary light reflex significantly when compared to steady light with 9-fold more energy density. Employing our findings, a new form of LED light is proposed to enhance subconscious visual responses at a typical indoor illuminance level. Using the silent substitution technique, a melanopsin-selective flicker is introduced into the light. A linear optimization algorithm is used to maximize the contrast of the subconscious, melanopsin-based response function while keeping conscious, cone-driven responses to the pulsing light fixed. Additional boundary conditions utilizing test color samples as an environmental mimic are introduced to limit the amount of perceived color change in a simulated environment. Two examples of lights are given to illustrate potential applications for general illumination and therapeutic purposes. For the lighting and electronics industry, we hope our study of subconscious-stimulative thresholds at night will better inform their design guidelines for health conscious products.

Enhanced optical coupling and Raman scattering via microscopic interface engineering

NASA Astrophysics Data System (ADS)

Thompson, Jonathan V.; Hokr, Brett H.; Kim, Wihan; Ballmann, Charles W.; Applegate, Brian E.; Jo, Javier A.; Yamilov, Alexey; Cao, Hui; Scully, Marlan O.; Yakovlev, Vladislav V.

2017-11-01

Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at least two-orders of magnitude more spontaneous Raman scattering from a sample when the pump laser light is focused into a microscopic hole in the surface of the sample. Because this approach enhances both the interaction time and interaction region of the laser light within the material, its use will greatly improve the range and sensitivity of many spectroscopic techniques, including Raman scattering and fluorescence emission detection, inside highly scattering environments.

Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides

PubMed Central

Yan, Siqi; Zhu, Xiaolong; Frandsen, Lars Hagedorn; Xiao, Sanshui; Mortensen, N. Asger; Dong, Jianji; Ding, Yunhong

2017-01-01

Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light–matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally demonstrate an energy-efficient graphene microheater with a tuning efficiency of 1.07 nmmW−1 and power consumption per free spectral range of 3.99 mW. The rise and decay times (10–90%) are only 750 and 525 ns, which, to the best of our knowledge, are the fastest reported response times for microheaters in silicon photonics. The corresponding figure of merit of the device is 2.543 nW s, one order of magnitude better than results reported in previous studies. The influence of the length and shape of the graphene heater to the tuning efficiency is further investigated, providing valuable guidelines for enhancing the tuning efficiency of the graphene microheater. PMID:28181531

Z-scheme Ag3PO4/POM/GO heterojunction with enhanced photocatalytic performance for degradation and water splitting.

PubMed

Liu, Guodong; Zhao, Xinfu; Zhang, Jian; Liu, Shaojie; Sha, Jingquan

2018-05-01

To develop solar light-driven photocatalysts with high activity and structural stability, Ag3PO4/POM/GO heterojunction has been successfully prepared by a facile method at room temperature. Ag3PO4/POM/GO shows remarkably enhanced activity and stability for photocatalytic degradation and H2 production from water-splitting under simulated solar light. The degradation rate of Ag3PO4/POM/GO is 1.8 times and 1.2 times those of Ag3PO4 and Ag3PO4/POMs, respectively. H2 production using Ag3PO4/POM/GO is 2.0 times that of Ag3PO4/GO. The enhanced photocatalytic performance of Ag3PO4/POM/GO is attributed to the increased surface area, electronegativity and structure stability. The Z-scheme system of Ag3PO4/POM/GO effectively promotes charge separation, resulting in enhanced photocatalytic performance under simulated solar light.

Highly efficient phosphor-converted white organic light-emitting diodes with moderate microcavity and light-recycling filters.

PubMed

Cho, Sang-Hwan; Oh, Jeong Rok; Park, Hoo Keun; Kim, Hyoung Kun; Lee, Yong-Hee; Lee, Jae-Gab; Do, Young Rag

2010-01-18

We demonstrate the combined effects of a microcavity structure and light-recycling filters (LRFs) on the forward electrical efficiency of phosphor-converted white organic light-emitting diodes (pc-WOLEDs). The introduction of a single pair of low- and high-index layers (SiO(2)/TiO(2)) improves the blue emission from blue OLED and the insertion of blue-passing and yellow-reflecting LRFs enhances the forward yellow emission from the YAG:Ce(3+) phosphors layers. The enhancement of the luminous efficacy of the forward white emission is 1.92 times that of a conventional pc-WOLED with color coordinates of (0.34, 0.34) and a correlated color temperature of about 4800 K.

Anomalous change in dielectric constant of CaCu{sub 3}Ti{sub 4}O{sub 12} under violet-to-ultraviolet irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masingboon, C.; Faculty of Science and Engineering, Kasetsart University, Chalermphrakiat Sakon Nakhon Province Campus, Sakon Nakhon 47000; Eknapakul, T.

2013-05-20

The influence of light illumination on the dielectric constant of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) polycrystals is studied in this work. When exposed to 405-nm laser light, a reversible enhancement in the room temperature capacitance as high as 22% was observed, suggesting application of light-sensitive capacitance devices. To uncover the microscopic mechanisms mediating this change, we performed electronic structure measurements, using photoemission spectroscopy, and measured the electrical conductivity of the CCTO samples under different conditions of light exposure and oxygen partial pressure. Together, these results suggest that the large capacitance enhancement is driven by oxygen vacancies induced by the irradiation.

Enhanced hole transport in InGaN/GaN multiple quantum well light-emitting diodes with a p-type doped quantum barrier.

PubMed

Ji, Yun; Zhang, Zi-Hui; Tan, Swee Tiam; Ju, Zhen Gang; Kyaw, Zabu; Hasanov, Namig; Liu, Wei; Sun, Xiao Wei; Demir, Hilmi Volkan

2013-01-15

We study hole transport behavior of InGaN/GaN light-emitting diodes with the dual wavelength emission method. It is found that at low injection levels, light emission is mainly from quantum wells near p-GaN, indicating that hole transport depth is limited in the active region. Emission from deeper wells only occurs under high current injection. However, with Mg-doped quantum barriers, holes penetrate deeper within the active region even under low injection, increasing the radiative recombination. Moreover, the improved hole transport leads to reduced forward voltage and enhanced light generation. This is also verified by numerical analysis of hole distribution and energy band structure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Wei, E-mail: wguo2@ncsu.edu; Kirste, Ronny; Bryan, Zachary

Enhanced light extraction efficiency was demonstrated on nanostructure patterned GaN and AlGaN/AlN Multiple-Quantum-Well (MQW) structures using mass production techniques including natural lithography and interference lithography with feature size as small as 100 nm. Periodic nanostructures showed higher light extraction efficiency and modified emission profile compared to non-periodic structures based on integral reflection and angular-resolved transmission measurement. Light extraction mechanism of macroscopic and microscopic nanopatterning is discussed, and the advantage of using periodic nanostructure patterning is provided. An enhanced photoluminescence emission intensity was observed on nanostructure patterned AlGaN/AlN MQW compared to as-grown structure, demonstrating a large-scale and mass-producible pathway to higher lightmore » extraction efficiency in deep-ultra-violet light-emitting diodes.« less

Plasmonic Enhancement Mechanisms in Solar Energy Harvesting

NASA Astrophysics Data System (ADS)

Cushing, Scott K.

Semiconductor photovoltaics (solar-to-electrical) and photocatalysis (solar-to-chemical) requires sunlight to be converted into excited charge carriers with sufficient lifetimes and mobility to drive a current or photoreaction. Thin semiconductor films are necessary to reduce the charge recombination and mobility losses, but thin films also limit light absorption, reducing the solar energy conversion efficiency. Further, in photocatalysis, the band edges of semiconductor must straddle the redox potentials of a photochemical reaction, reducing light absorption to half the solar spectrum in water splitting. Plasmonics transforms metal nanoparticles into antennas with resonances tuneable across the solar spectrum. If energy can be transferred from the plasmon to the semiconductor, light absorption in the semiconductor can be increased in thin films and occur at energies smaller than the band gap. This thesis investigates why, despite this potential, plasmonic solar energy harvesting techniques rarely appear in top performing solar architectures. To accomplish this goal, the possible plasmonic enhancement mechanisms for solar energy conversion were identified, isolated, and optimized by combining systematic sample design with transient absorption spectroscopy, photoelectrochemical and photocatalytic testing, and theoretical development. Specifically, metal semiconductor nanostructures were designed to modulate the plasmon's scattering, hot carrier, and near field interactions as well as remove heating and self-catalysis effects. Transient absorption spectroscopy then revealed how the structure design affected energy and charge carrier transfer between metal and semiconductor. Correlating this data with wavelength-dependent photoconversion efficiencies and theoretical developments regarding metal-semiconductor interactions identified the origin of the plasmonic enhancement. Using this methodology, it has first been proven that three plasmonic enhancement routes are possible: i) increasing light absorption in the semiconductor by light trapping through scattering, ii) transferring hot carriers from metal to semiconductor after light absorption in the metal, and iii) non-radiative excitation of interband transitions in the semiconductor by plasmon-induced resonant energy transfer (PIRET). The effects of the metal on charge transport and carrier recombination were also revealed. Next, it has been shown that the strength and balance of the three enhancement mechanisms is rooted in the plasmon's dephasing time, or how long it takes the collective electron oscillations to stop being collective. The importance of coherent effects in plasmonic enhancement is also shown. Based on these findings, a thermodynamic balance framework has been used to predict the theoretical maximum efficiency of solar energy conversion in plasmonic metal-semiconductor heterojunctions. These calculations have revealed how plasmonics is best used to address the different light absorption problems in semiconductors, and that not taking into account the plasmon's dephasing is the origin of low plasmonic enhancement Finally, to prove these guidelines, each of the three enhancement mechanisms has been translated into optimal device geometries, showing the plasmon's potential for solar energy harvesting. This dissertation identifies the three possible plasmonic enhancement mechanisms for the first time, discovering a new enhancement mechanism (PIRET) in the process. It has also been shown for the first time that the various plasmon-semiconductor interactions could be rooted in the plasmon's dephasing. This has allowed for the first maximum efficiency estimates which have combined all three enhancement mechanisms to be performed, and revealed that changes in the plasmon's dephasing leads to the disparity in reported plasmonic enhancements. These findings are combined to create optimal device design guidelines, which are proven by fabrication of several devices with top efficiencies in plasmonic solar energy conversion. The knowledge obtained will guide the design of efficient photovoltaics and photocatalysts, helping usher in a renewable energy economy and address current needs of climate change.

Pressure enhanced penetration with shaped charge perforators

DOEpatents

Glenn, Lewis A.

2001-01-01

A downhole tool, adapted to retain a shaped charge surrounded by a superatmospherically pressurized light gas, is employed in a method for perforating a casing and penetrating reservoir rock around a wellbore. Penetration of a shaped charge jet can be enhanced by at least 40% by imploding a liner in the high pressure, light gas atmosphere. The gas pressure helps confine the jet on the axis of penetration in the latter stages of formation. The light gas, such as helium or hydrogen, is employed to keep the gas density low enough so as not to inhibit liner collapse.

Surface photonic crystal structures for LED emission modification

NASA Astrophysics Data System (ADS)

Uherek, Frantisek; Škriniarová, Jaroslava; Kuzma, Anton; Šušlik, Łuboš; Lettrichova, Ivana; Wang, Dong; Schaaf, Peter

2017-12-01

Application of photonic crystal structures (PhC) can be attractive for overall and local enhancement of light from patterned areas of the light emitting diode (LED) surface. We used interference and near-field scanning optical microscope lithography for patterning of the surface of GaAs/AlGaAs based LEDs emitted at 840 nm. Also new approach with patterned polydimethylsiloxane (PDMS) membrane applied directly on the surface of red emitting LED was investigated. The overall emission properties of prepared LED with patterned structure show enhanced light extraction efficiency, what was documented from near- and far-field measurements.

Graphene oxide quantum dot-sensitized porous titanium dioxide microsphere: Visible-light-driven photocatalyst based on energy band engineering.

PubMed

Zhang, Yu; Qi, Fuyuan; Li, Ying; Zhou, Xin; Sun, Hongfeng; Zhang, Wei; Liu, Daliang; Song, Xi-Ming

2017-07-15

We report a novel graphene oxide quantum dot (GOQD)-sensitized porous TiO 2 microsphere for efficient photoelectric conversion. Electro-chemical analysis along with the Mott-Schottky equation reveals conductivity type and energy band structure of the two semiconductors. Based on their energy band structures, visible light-induced electrons can transfer from the p-type GOQD to the n-type TiO 2 . Enhanced photocurrent and photocatalytic activity in visible light further confirm the enhanced separation of electrons and holes in the nanocomposite. Copyright © 2017 Elsevier Inc. All rights reserved.

Approach to Low-Cost High-Efficiency OLED Lighting. Building Technologies Solid State Lighting (SSL) Program Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pei, Qibing

2017-10-06

This project developed an integrated substrate which organic light emitting diode (OLED) panel developers could employ the integrated substrate to fabricate OLED devices with performance and projected cost meeting the MYPP targets of the Solid State Lighting Program of the Department of Energy. The project optimized the composition and processing conditions of the integrated substrate for OLED light extraction efficiency and overall performance. The process was further developed for scale up to a low-cost process and fabrication of prototype samples. The encapsulation of flexible OLEDs based on this integrated substrate was also investigated using commercial flexible barrier films.

Upconversion induced enhancement of dye sensitized solar cells based on core-shell structured β-NaYF4:Er3+, Yb3+@SiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Zhou, Ziyao; Wang, Jiahong; Nan, Fan; Bu, Chenghao; Yu, Zhenhua; Liu, Wei; Guo, Shishang; Hu, Hao; Zhao, Xing-Zhong

2014-01-01

Upconversion materials have been employed as energy relay materials in dye sensitized solar cells (DSCs) to broaden the range of light absorption. However, the origin of the enhancements can be induced by both upconversion and size-dependent light scattering effects. To clarify the role of the upconversion material in the photoelectrode of DSCs, an upconversion induced device was realized here, which has the size-dependent light scattering effect eliminated via the application of NaYF4:Er3+, Yb3+@SiO2 upconversion nanoparticles (β-NYEY@SiO2 UCNPs). An enhancement of 6% in efficiency was observed for the device. This demonstration provided an insight into the possible further employment of upconversion in DSCs.Upconversion materials have been employed as energy relay materials in dye sensitized solar cells (DSCs) to broaden the range of light absorption. However, the origin of the enhancements can be induced by both upconversion and size-dependent light scattering effects. To clarify the role of the upconversion material in the photoelectrode of DSCs, an upconversion induced device was realized here, which has the size-dependent light scattering effect eliminated via the application of NaYF4:Er3+, Yb3+@SiO2 upconversion nanoparticles (β-NYEY@SiO2 UCNPs). An enhancement of 6% in efficiency was observed for the device. This demonstration provided an insight into the possible further employment of upconversion in DSCs. Electronic supplementary information (ESI) available: Details of preparations and characterizations; the TEM images, EDX measurements, XRD measurements and upconversion emission spectrum of bared β-NYEY nanocrystals; SEM and AFM images of the photoelectrode with different concentrations of β-NYEY nanocrystals; J-V characteristics, EIS measurements and fitted EIS parameters of the DSCs based on five different photoelectrodes. See DOI: 10.1039/c3nr04315k

Enhancement of light absorption in polyazomethines due to plasmon excitation on randomly distributed metal nanoparticles

NASA Astrophysics Data System (ADS)

Wróbel, P.; Antosiewicz, T. J.; Stefaniuk, T.; Ciesielski, A.; Iwan, A.; Wronkowska, A. A.; Wronkowski, A.; Szoplik, T.

2015-05-01

In photovoltaic devices, metal nanoparticles embedded in a semiconductor layer allow the enhancement of solar-toelectric energy conversion efficiency due to enhanced light absorption via a prolonged optical path, enhanced electric fields near the metallic inclusions, direct injection of hot electrons, or local heating. Here we pursue the first two avenues. In the first, light scattered at an angle beyond the critical angle for reflection is coupled into the semiconductor layer and confined within such planar waveguide up to possible exciton generation. In the second, light is trapped by the excitation of localized surface plasmons on metal nanoparticles leading to enhanced near-field plasmon-exciton coupling at the peak of the plasmon resonance. We report on results of a numerical experiment on light absorption in polymer- (fullerene derivative) blends, using the 3D FDTD method, where exact optical parameters of the materials involved are taken from our recent measurements. In simulations we investigate light absorption in randomly distributed metal nanoparticles dispersed in polyazomethine-(fullerene derivative) blends, which serve as active layers in bulkheterojunction polymer solar cells. In the study Ag and Al nanoparticles of different diameters and fill factors are diffused in two air-stable aromatic polyazomethines with different chemical structures (abbreviated S9POF and S15POF) mixed with phenyl-C61-butyric acid methyl ester (PCBM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The mixtures are spin coated on a 100 nm thick Al layer deposited on a fused silica substrate. Optical constants of the active layers are taken from spectroscopic ellipsometry and reflectance measurements using a rotating analyzer type ellipsometer with auto-retarder performed in the wavelength range from 225 nm to 2200 nm. The permittivities of Ag and Al particles of diameters from 20 to 60 nm are assumed to be equal to those measured on 100 to 200 nm thick metal films.

Pathogen inactivation by riboflavin and ultraviolet light illumination accelerates the red blood cell storage lesion and promotes eryptosis.

PubMed

Qadri, Syed M; Chen, Deborah; Schubert, Peter; Perruzza, Darian L; Bhakta, Varsha; Devine, Dana V; Sheffield, William P

2017-03-01

Pathogen reduction treatment using riboflavin and ultraviolet light illumination (Mirasol) effectively reduces the risk of transfusion-transmitted infections. This treatment is currently licensed for only platelets and plasma products, while its application to whole blood (WB) to generate pathogen-inactivated red blood cells (RBCs) is under development. RBC storage lesion, constituting numerous morphologic and biochemical changes, influences RBC quality and limits shelf life. Stored RBCs further show enhanced susceptibility to RBC programmed cell death (eryptosis) characterized by increased cytosolic Ca 2+ -provoked membrane phosphatidylserine (PS) externalization. Using a "pool-and-split" approach, we examined multiple variables of RBC storage lesion and eryptosis in RBC units, derived from Mirasol-treated or untreated WB, after 4 to 42 days of storage, under blood bank conditions. In comparison to untreated RBC units, Mirasol treatment significantly altered membrane microvesiculation, supernatant hemoglobin, osmotic fragility, and intracellular adenosine triphosphate levels but did not influence membrane CD47 expression and 2,3-diphosphoglycerate levels. Mirasol-treated RBCs showed significantly higher PS exposure after 42, but not after not more than 21, days of storage, which was accompanied by enhanced cytosolic Ca 2+ activity, ceramide abundance, and oxidative stress, but not p38 kinase activation. Mirasol treatment significantly augmented PS exposure, Ca 2+ entry, and protein kinase C activation after energy depletion, a pathophysiologic cell stressor. Mirasol-treated RBCs were, however, more resistant to cell shrinkage. Prolonged storage of Mirasol-treated RBCs significantly increases the proportion of eryptotic RBCs, while even short-term storage enhances the susceptibility of RBCs to stress-induced eryptosis, which could reduce posttransfusion RBC recovery in patients. © 2016 AABB.

Dim light at night interferes with the development of the short-day phenotype and impairs cell-mediated immunity in Siberian hamsters (Phodopus sungorus).

PubMed

Aubrecht, Taryn G; Weil, Zachary M; Nelson, Randy J

2014-10-01

Winter is a challenging time to survive and breed outside of the tropics. Animals use day length (photoperiod) to regulate seasonally appropriate adaptations in anticipation of challenging winter conditions. The net result of these photoperiod-mediated adjustments is enhanced immune function and increased survival. Thus, the ability to discriminate day length information is critical for survival and reproduction in small animals. However, during the past century, urban and suburban development has rapidly expanded and filled the night sky with light from various sources, obscuring crucial light-dark signals, which alters physiological interpretation of day lengths. Furthermore, reduced space, increased proximity to people, and the presence of light at night may act as stressors for small animals. Whereas acute stressors typically enhance immune responses, chronic exposure to stressors often impairs immune responses. Therefore, we hypothesized that the combination of dim light at night and chronic stress interferes with enhanced cell-mediated immunity observed during short days. Siberian hamsters (Phodopus sungorus) were assigned to short or long days with dark nights (0 lux) or dim (5 lux) light at night for 10 weeks. Following 2 weeks of chronic restraint (6 hr/day), a model of chronic stress, delayed type hypersensitivity (DTH) responses were assessed. Both dim light at night and restraint reduced the DTH response. Dim light at night during long nights produced an intermediate short day phenotype. These results suggest the constant presence of light at night could negatively affect survival of photoperiodic rodents by disrupting the timing of breeding and immune responses. © 2014 Wiley Periodicals, Inc.

The ctenidium of the giant clam, Tridacna squamosa, expresses an ammonium transporter 1 that displays light-suppressed gene and protein expression and may be involved in ammonia excretion.

PubMed

Boo, Mel V; Hiong, Kum C; Goh, Enan J K; Choo, Celine Y L; Wong, Wai P; Chew, Shit F; Ip, Yuen K

2018-04-24

Ammonium transporters (AMTs) can participate in ammonia uptake or excretion across the plasma membrane of prokaryotic, plant and invertebrate cells. The giant clam, Tridacna squamosa, harbors nitrogen-deficient symbiotic zooxanthellae, and normally conducts light-enhanced ammonia absorption to benefit the symbionts. Nonetheless, it can excrete ammonia when there is a supply of exogenous nitrogen or exposed to continuous darkness. This study aimed to elucidate the role of AMT1 in the ctenidium of T. squamosa by cloning and characterizing the AMT1/AMT1, determining its subcellular localization, and examining changes in its transcript and protein expression levels in response to light exposure. The cDNA coding sequence of AMT1 from T. squamosa consisted of 1527 bp and encoded 508 amino acids of 54.6 kDa. AMT1-immunofluorescence was detected mainly at the apical epithelium of ctenidial filaments, and it decreased significantly after 12 h of exposure to light. By contrast, the epithelial cells surrounding the tertiary water channels in the ctentidium, which are known to exhibit light-enhanced glutamine synthetase expression and take part in the assimilation of exogenous ammonia in light, did not display any AMT1-immunolabelling. Furthermore, the transcript level and protein abundance of ctenidial AMT1/AMT1 decreased significantly at the 6th and 12th h of light exposure. Taken together, these results indicate that AMT1 might participate in ammonia excretion instead of ammonia absorption and assimilation in T. squamosa. It is probable that the expression levels of AMT1/AMT1 need to be down-regulated during light exposure to achieve light-enhanced ammonia uptake.

10 CFR Appendix V to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Ceiling Fan Light Kits

Code of Federal Regulations, 2013 CFR

2013-01-01

... for Testing” of DOE's “ENERGY STAR Program Requirements for [Compact Fluorescent Lamps] CFLs,” Version... Specifications for Qualifying Products” of the EPA's “ENERGY STAR Program Requirements for Residential Light... requirements specified in section 4, “CFL Requirements for Testing,” of the “ENERGY STAR Program Requirements...

10 CFR Appendix V to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Ceiling Fan Light Kits

Code of Federal Regulations, 2014 CFR

2014-01-01

... for Testing” of DOE's “ENERGY STAR Program Requirements for [Compact Fluorescent Lamps] CFLs,” Version... Specifications for Qualifying Products” of the EPA's “ENERGY STAR Program Requirements for Residential Light... requirements specified in section 4, “CFL Requirements for Testing,” of the “ENERGY STAR Program Requirements...

10 CFR Appendix V to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Ceiling Fan Light Kits

Code of Federal Regulations, 2012 CFR

2012-01-01

... for Testing” of DOE's “ENERGY STAR Program Requirements for [Compact Fluorescent Lamps] CFLs,” Version... Specifications for Qualifying Products” of the EPA's “ENERGY STAR Program Requirements for Residential Light... requirements specified in section 4, “CFL Requirements for Testing,” of the “ENERGY STAR Program Requirements...

Dark Skies Awareness Programs for the International Year of Astronomy: Involvement, Outcomes and Sustainability

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2010-01-01

The preservation of dark skies is a growing global concern, yet it is one of the easiest environmental problems people can address on local levels. For this reason, the goal of the IYA Dark Skies Awareness Cornerstone Project is to raise public awareness of the impact of artificial lighting on local environments by getting people worldwide involved in a variety of programs. These programs provide resources on light pollution for new technologies like a presence in Second Life and podcasts, for local thematic events at national parks and observatory open houses, for international thematic events like International Dark Skies Week and Earth Hour, for a program in the arts like an international photo contest, for global citizen-science programs that measure night sky brightness worldwide, and for educational materials like a kit with a light shielding demonstration. These programs have been successfully used around the world during IYA to raise awareness of the effects of light pollution on public health, economic issues, ecological consequences, energy conservation, safety and security, and astronomy. The presentation will provide an update, take a look ahead at the project's sustainability, and describe how people can be involved in the future. Information about the programs is at www.darkskiesawareness.org.

Promoting Dark Skies Awareness Programs Beyond the International Year of Astronomy 2009

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Dark Skies Working Group

2010-01-01

The preservation of dark skies is a growing global concern, yet it is one of the easiest environmental problems people can address on local levels. For this reason, the goal of the International Year of Astronomy 2009 (IYA2009) Dark Skies Awareness Cornerstone Project is to raise public awareness of the impact of artificial lighting on local environments by getting people worldwide involved in a variety of programs. These programs provide resources on light pollution for new technologies like a presence in Second Life and podcasts, for local thematic events at national parks and observatory open houses, for international thematic events like International Dark Skies Week and Earth Hour, for a program in the arts like an international photo contest, for global citizen-science programs that measure night sky brightness worldwide, and for educational materials like a kit with a light shielding demonstration. These programs have been successfully used around the world during IYA2009 to raise awareness of the effects of light pollution on public health, economic issues, ecological consequences, energy conservation, safety and security, and astronomy. The poster will provide an update, take a look ahead at the project's sustainability, and describe how people can be involved in the future. Information about the programs is at www.darkskiesawareness.org.

Time-resolved measurements of black carbon light absorption enhancement in urban and near-urban locations of Southern Ontario, Canada

NASA Astrophysics Data System (ADS)

Chan, T. W.; Brook, J. R.; Smallwood, G. J.; Lu, G.

2010-08-01

In this study a photoacoustic spectrometer (PA), a laser-induced incandescence instrument system (LII) and an aerosol mass spectrometer were operated in parallel for in situ measurements of black carbon (BC) light absorption enhancement. Results of a thermodenuder experiment using ambient particles in Toronto are presented first to show that LII measurements of BC are not influenced by particle coating while the PA response is enhanced and also that the nature of this enhancement is influenced by particle morphology. Comparisons of ambient PA and LII measurements at four different locations (suburban Toronto; a street canyon with heavy diesel bus traffic in Ottawa; adjacent to a commuter highway in Ottawa and; regional background air in and around Windsor, Ontario), show that the different meteorological conditions and atmospheric processes result in different particle light absorption enhancement and hence the specific attenuation coefficient (SAC). Depending upon location of measurement and the BC spherule diameter (primary particle size - PPS) measurement from the LII, the SAC varies from 2.6±0.04 to 22.5±0.7 m2 g-1. Observations from this study also show the active surface area of the BC aggregate, inferred from PPS, is an important parameter for inferring the degree of particle collapse of a BC particle. The predictability of the overall BC light absorption enhancement in the atmosphere depends not only on the coating mass but also on the source of the BC and on our ability to predict or measure the change in particle morphology as particles evolve.

Local adaptive contrast enhancement for color images

NASA Astrophysics Data System (ADS)

Dijk, Judith; den Hollander, Richard J. M.; Schavemaker, John G. M.; Schutte, Klamer

2007-04-01

A camera or display usually has a smaller dynamic range than the human eye. For this reason, objects that can be detected by the naked eye may not be visible in recorded images. Lighting is here an important factor; improper local lighting impairs visibility of details or even entire objects. When a human is observing a scene with different kinds of lighting, such as shadows, he will need to see details in both the dark and light parts of the scene. For grey value images such as IR imagery, algorithms have been developed in which the local contrast of the image is enhanced using local adaptive techniques. In this paper, we present how such algorithms can be adapted so that details in color images are enhanced while color information is retained. We propose to apply the contrast enhancement on color images by applying a grey value contrast enhancement algorithm to the luminance channel of the color signal. The color coordinates of the signal will remain the same. Care is taken that the saturation change is not too high. Gamut mapping is performed so that the output can be displayed on a monitor. The proposed technique can for instance be used by operators monitoring movements of people in order to detect suspicious behavior. To do this effectively, specific individuals should both be easy to recognize and track. This requires optimal local contrast, and is sometimes much helped by color when tracking a person with colored clothes. In such applications, enhanced local contrast in color images leads to more effective monitoring.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Yung-Ting; Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan 10617, Taiwan; Liu, Shun-Wei

Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less lightmore » than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts.« less

Enhanced Cellular Ablation by Attenuating Hypoxia Status and Reprogramming Tumor-Associated Macrophages via NIR Light-Responsive Upconversion Nanocrystals.

PubMed

Ai, Xiangzhao; Hu, Ming; Wang, Zhimin; Lyu, Linna; Zhang, Wenmin; Li, Juan; Yang, Huanghao; Lin, Jun; Xing, Bengang

2018-04-18

Near-infrared (NIR) light-mediated photodynamic therapy (PDT), especially based on lanthanide-doped upconversion nanocrystals (UCNs), have been extensively investigated as a promising strategy for effective cellular ablation owing to their unique optical properties to convert NIR light excitation into multiple short-wavelength emissions. Despite the deep tissue penetration of NIR light in living systems, the therapeutic efficiency is greatly restricted by insufficient oxygen supply in hypoxic tumor microenvironment. Moreover, the coexistent tumor-associated macrophages (TAMs) play critical roles in tumor recurrence during the post-PDT period. Herein, we developed a unique photosensitizer-loaded UCNs nanoconjugate (PUN) by integrating manganese dioxide (MnO 2 ) nanosheets and hyaluronic acid (HA) biopolymer to improve NIR light-mediated PDT efficacy through attenuating hypoxia status and synergistically reprogramming TAMs populations. After the reaction with overproduced H 2 O 2 in acidic tumor microenvironment, the MnO 2 nanosheets were degraded for the production of massive oxygen to greatly enhance the oxygen-dependent PDT efficiency upon 808 nm NIR light irradiation. More importantly, the bioinspired polymer HA could effectively reprogram the polarization of pro-tumor M2-type TAMs to anti-tumor M1-type macrophages to prevent tumor relapse after PDT treatment. Such promising results provided the great opportunities to achieve enhanced cellular ablation upon NIR light-mediated PDT treatment by attenuating hypoxic tumor microenvironment, and thus facilitated the rational design of new generations of nanoplatforms toward immunotherapy to inhibit tumor recurrence during post-PDT period.

Improved light-extraction efficiency from organic light-emitting diodes using hazy SiO2 thin films created by using an aerosol-deposition method

NASA Astrophysics Data System (ADS)

Moon, Byung Seuk; Lee, Soo-Hyoung; Huh, Yoon Ho; Kwon, O. Eun; Park, Byoungchoo; Lee, Bumjoo; Lee, Seung-Hyun; Hwang, Inchan

2015-04-01

We herein report an investigation of the effect of rough thin films of SiO2 granules deposited on glass substrates of organic light-emitting devices (OLEDs) by using a simple, low-cost and scalable process based on a powder spray of SiO2 granules in vacuum, known as the aerosol-deposition method, with regard to their external light-extraction capabilities. The rough and hazy thin SiO2 films produced by using aerosol-deposition and acting as scattering centers were able to efficiently reduce the light-trapping loss in the glass substrate (glass mode) for internally-generated photons and to enhance the external quantum efficiency (EQE) of the OLEDs. Based on aerosol-deposited silica films with a thickness of 800 nm and a haze of 22% on glass substrates, the EQE of phosphorescent green OLEDs was found to be enhanced by 17%, from an EQE of 7.0% for smooth bare glass substrates to an EQE of 8.2%. Furthermore, the EQEs of fluorescent blue and phosphorescent red OLEDs were shown to be enhanced by 16%, from an EQE of 3.7% to 4.3%, and by 16%, from an EQE of 9.3% to 10.8%, respectively. These improvements in the EQEs without serious changes in the emission spectra or the Lambertian emitter property clearly indicate the high potential of the aerosol-deposition technique for the realization of highly-efficient light extraction in colorful OLED lighting.

NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Research on Materials for the High Speed Civil Transport

NASA Technical Reports Server (NTRS)

Gangloff, Richard P.; Starke, Edgar A., Jr.; Kelly, Robert G.; Scully, John R.; Stoner, Glenn E.; Wert, John A.

1997-01-01

Since 1986, the NASA-Langley Research Center has sponsored the NASA-UVa Light Alloy and Structures Technology (LA2ST) Program at the University of Virginia (UVa). The fundamental objective of the LA2ST program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures. The LA2ST program has aimed to product relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. The scope of the LA2ST Program is broad. Research areas include: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals and Composites, (2) Aerospace Materials Science, (3) Mechanics of materials for Aerospace Structures, and (4) Thermal Gradient Structures. A substantial series of semi-annual progress reports issued since 1987 documents the technical objectives, experimental or analytical procedures, and detailed results of graduate student research in these topical areas.

Enhancing programming logic thinking using analogy mapping

NASA Astrophysics Data System (ADS)

Sukamto, R. A.; Megasari, R.

2018-05-01

Programming logic thinking is the most important competence for computer science students. However, programming is one of the difficult subject in computer science program. This paper reports our work about enhancing students' programming logic thinking using Analogy Mapping for basic programming subject. Analogy Mapping is a computer application which converts source code into analogies images. This research used time series evaluation and the result showed that Analogy Mapping can enhance students' programming logic thinking.

Designing metal hemispheres on silicon ultrathin film solar cells for plasmonic light trapping.

PubMed

Gao, Tongchuan; Stevens, Erica; Lee, Jung-kun; Leu, Paul W

2014-08-15

We systematically investigate the design of two-dimensional silver (Ag) hemisphere arrays on crystalline silicon (c-Si) ultrathin film solar cells for plasmonic light trapping. The absorption in ultrathin films is governed by the excitation of Fabry-Perot TEMm modes. We demonstrate that metal hemispheres can enhance absorption in the films by (1) coupling light to c-Si film waveguide modes and (2) exciting localized surface plasmon resonances (LSPRs). We show that hemisphere arrays allow light to couple to fundamental TEm and TMm waveguide modes in c-Si film as well as higher-order versions of these modes. The near-field light concentration of LSPRs also may increase absorption in the c-Si film, though these resonances are associated with significant parasitic absorption in the metal. We illustrate how Ag plasmonic hemispheres may be utilized for light trapping with 22% enhancement in short-circuit current density compared with that of a bare 100 nm thick c-Si ultrathin film solar cell.

Enhancement of light output power of GaN-based light-emitting diodes with photonic quasi-crystal patterned on p-GaN surface and n-side sidewall roughing.

PubMed

Lai, Fang-I; Yang, Jui-Fu

2013-05-17

In this paper, GaN-based light-emitting diodes (LEDs) with photonic quasi-crystal (PQC) structure on p-GaN surface and n-side roughing by nano-imprint lithography are fabricated and investigated. At an injection current of 20 mA, the LED with PQC structure on p-GaN surface and n-side roughing increased the light output power of the InGaN/GaN multiple quantum well LEDs by a factor of 1.42, and the wall-plug efficiency is 26% higher than the conventional GaN-based LED type. After 500-h life test (55°C/50 mA), it was found that the normalized output power of GaN-based LED with PQC structure on p-GaN surface and n-side roughing only decreased by 6%. These results offer promising potential to enhance the light output powers of commercial light-emitting devices using the technique of nano-imprint lithography.

Self-rolling and light-trapping in flexible quantum well–embedded nanomembranes for wide-angle infrared photodetectors

PubMed Central

Wang, Han; Zhen, Honglou; Li, Shilong; Jing, Youliang; Huang, Gaoshan; Mei, Yongfeng; Lu, Wei

2016-01-01

Three-dimensional (3D) design and manufacturing enable flexible nanomembranes to deliver unique properties and applications in flexible electronics, photovoltaics, and photonics. We demonstrate that a quantum well (QW)–embedded nanomembrane in a rolled-up geometry facilitates a 3D QW infrared photodetector (QWIP) device with enhanced responsivity and detectivity. Circular geometry of nanomembrane rolls provides the light coupling route; thus, there are no external light coupling structures, which are normally necessary for QWIPs. This 3D QWIP device under tube-based light-trapping mode presents broadband enhancement of coupling efficiency and omnidirectional detection under a wide incident angle (±70°), offering a unique solution to high-performance focal plane array. The winding number of these rolled-up QWIPs provides well-tunable blackbody photocurrents and responsivity. 3D self-assembly of functional nanomembranes offers a new path for high conversion efficiency between light and electricity in photodetectors, solar cells, and light-emitting diodes. PMID:27536723

Extraordinary light transmission through opaque thin metal film with subwavelength holes blocked by metal disks.

PubMed

Li, Wen-Di; Hu, Jonathan; Chou, Stephen Y

2011-10-10

We observed that when subwavelength-sized holes in an optically opaque metal film are completely covered by opaque metal disks larger than the holes, the light transmission through the holes is not reduced, but rather enhanced. Particularly we report (i) the observation of light transmission through the holes blocked by the metal disks up to 70% larger than the unblocked holes; (ii) the observation of tuning the light transmission by varying the coupling strength between the blocking disks and the hole array, or by changing the size of the disks and holes; (iii) the observation and simulation that the metal disk blocker can improve light coupling from free space to a subwavelength hole; and (iv) the simulation that shows the light transmission through subwavelength holes can be enhanced, even though the gap between the disk and the metal film is partially connected with a metal. We believe these finding should have broad and significant impacts and applications to optical systems in many fields.

Band gap narrowing in nitrogen-doped La2Ti2O7 predicted by density-functional theory calculations.

PubMed

Zhang, Junying; Dang, Wenqiang; Ao, Zhimin; Cushing, Scott K; Wu, Nianqiang

2015-04-14

In order to reveal the origin of enhanced photocatalytic activity of N-doped La2Ti2O7 in both the visible light and ultraviolet light regions, its electronic structure has been studied using spin-polarized conventional density functional theory (DFT) and the Heyd-Scuseria-Ernzerhof (HSE06) hybrid approach. The results show that the deep localized states are formed in the forbidden band when nitrogen solely substitutes for oxygen. Introducing the interstitial Ti atom into the N-doped La2Ti2O7 photocatalyst still causes the formation of a localized energy state. Two nitrogen substitutions co-exist stably with one oxygen vacancy, creating a continuum energy band just above the valence band maximum. The formation of a continuum band instead of mid-gap states can extend the light absorption to the visible light region without increasing the charge recombination, explaining the enhanced visible light performance without deteriorating the ultraviolet light photocatalytic activity.

Monte Carlo study of skin optical clearing to enhance light penetration in the tissue: implications for photodynamic therapy of acne vulgaris

NASA Astrophysics Data System (ADS)

Bashkatov, Alexey N.; Genina, Elina A.; Tuchin, Valery V.; Altshuler, Gregory B.; Yaroslavsky, Ilya V.

2008-06-01

Result of Monte Carlo simulations of skin optical clearing is presented. The model calculations were carried out with the aim of studying of spectral response of skin under immersion liquids action and calculation of enhancement of light penetration depth. In summary, we have shown that: 1) application of glucose, propylene glycol and glycerol produced significant decrease of light scattering in different skin layers; 2) maximal clearing effect will be obtained in case of optical clearing of skin dermis, however, absorbed light fraction in skin dermis changed insignificantly, independently on clearing agent and place it administration; 3) in contrast to it, the light absorbed fraction in skin adipose layer increased significantly in case of optical clearing of skin dermis. It is very important because it can be used for development of optical methods of obesity treatment; 4) optical clearing of superficial skin layers can be used for decreasing of power of light radiation used for treatment of acne vulgaris.

Benefit from NASA

NASA Image and Video Library

1999-01-01

The red light from the Light Emitting Diode (LED) probe shines through the fingers of Dr. Harry Whelan, a pediatric neurologist at the Children's Hospital of Wisconsin in Milwaukee. Dr. Whelan uses the long waves of light from the LED surgical probe to activate special drugs that kill brain tumors. Laser light previously has been used for this type of surgery, but the LED light illuminates through all nearby tissues, reaching parts of tumors that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. Also, it can be used for hours at a time while still remaining cool to the touch. The probe was developed for photodynamic cancer therapy under a NASA Small Business Innovative Research Program grant. The program is part of NASA's Technology Transfer Department at the Marshall Space Flight Center.

Chlorophyll derivatives enhance invertebrate red-light and ultraviolet phototaxis.

PubMed

Degl'Innocenti, Andrea; Rossi, Leonardo; Salvetti, Alessandra; Marino, Attilio; Meloni, Gabriella; Mazzolai, Barbara; Ciofani, Gianni

2017-06-13

Chlorophyll derivatives are known to enhance vision in vertebrates. They are thought to bind visual pigments (i.e., opsins apoproteins bound to retinal chromophores) directly within the retina. Consistent with previous findings in vertebrates, here we show that chlorin e 6 - a chlorophyll derivative - enhances photophobicity in a flatworm (Dugesia japonica), specifically when exposed to UV radiation (λ = 405 nm) or red light (λ = 660 nm). This is the first report of chlorophyll derivatives acting as modulators of invertebrate phototaxis, and in general the first account demonstrating that they can artificially alter animal response to light at a behavioral level. Our findings show that the interaction between chlorophyll derivatives and opsins virtually concerns the vast majority of bilaterian animals, and also occurs in visual systems based on rhabdomeric (rather than ciliary) opsins.

Heterogeneous Semiconductor Shells Sequentially Coated on Upconversion Nanoplates for NIR-Light Enhanced Photocatalysis.

PubMed

Cui, Cao; Tou, Meijie; Li, Mohua; Luo, Zhenguo; Xiao, Lingbo; Bai, Song; Li, Zhengquan

2017-02-20

Combination of upconversion nanocrystals (UCNs) with CeO 2 is a decent choice to construct NIR-activated photocatalysts for utilizing the NIR light in the solar spectrum. Herein we present a facile approach to deposit a CeO 2 layer with controllable thickness on the plate-shaped NaYF 4 :Yb,Tm UCNs. The developed core-shell nanocomposites display obvious photocatalytic activity under the NIR light and exhibit enhanced activity under the full solar spectrum. For enhancing the separation of photogenerated electrons and holes on the CeO 2 surface, we sequentially coat a ZnO shell on the nanocomposites so as to form a heterojunction structure for achieving a better activity. The developed hybrid photocatalysts have been characterized with TEM, SEM, PL, etc., and the working mechanism of such UCN-semiconductor heterojunction photocatalysts has been proposed.