Protective Effect of Highly Polymeric A-Type Proanthocyanidins from Seed Shells of Japanese Horse Chestnut (Aesculus turbinata BLUME) against Light-Induced Oxidative Damage in Rat Retina

PubMed Central

Ishihara, Tomoe; Kaidzu, Sachiko; Kimura, Hideto; Koyama, Yasurou; Matsuoka, Yotaro

2018-01-01

Retinal tissue is exposed to oxidative stress caused by visible light. Light-damaged rat used in age-related macular degeneration (AMD) studies clarified that antioxidants decrease retinal light damage. Albino rats were exposed to 5000 Lux light for 12 h with oral administration of the polyphenolic compounds fraction (PF) from the seed shells of Japanese horse chestnut (30 mg/kg, 100 mg/kg, and 300 mg/kg body weight: BW). To evaluate the protective effects against light damage, electroretinograms (ERGs), the outer nuclear layer (ONL) thickness, the antioxidant activity of plasma, oxidized retinal lipids, and the detection of apoptosis were examined. To reveal their active compounds, PF were separated into an A-type proanthocyanidin (PAF) and a flavonol O-glycosides fraction. The protective effects of these fractions against light damage were compared by measuring the thickness of the ERGs and ONL. Compared with the negative control, the PF group (100 mg/kg and 300 mg/kg BW) significantly suppressed the decrease of the ERG amplitudes and ONL thickness. PF (300 mg/kg BW) induced the elevation of in vivo antioxidant activity, and the suppression of retinal lipid oxidation. PF administration also suppressed apoptotic cell death. The protective effects against light damage were attributable to the antioxidant activity of PAF. The light-induced damage of retinas was protected by oral administration of PF and PAF. Taken together, these compounds are potentially useful for the prevention of the disease caused by light exposure. Highlights: The protective effects of retinal damage by light exposure were evaluated using polyphenolic compounds from the seed shells of Japanese horse chestnut (Aesculus turbinata BLUME) as an antioxidant. Decreases in the electroretinographic amplitude and outer nuclear layer thickness were suppressed by the polyphenolic compounds of the seed shells. Polyphenolic compounds from the seed shells of Japanese horse chestnut inhibited the oxidation of retinal lipids. Highly polymeric A-type proanthocyanidin from the seed shells protected the rat retina from light exposure damage by inhibiting oxidative stress and apoptotic mechanisms. PMID:29748512

Protective Effect of Highly Polymeric A-Type Proanthocyanidins from Seed Shells of Japanese Horse Chestnut (Aesculus turbinata BLUME) against Light-Induced Oxidative Damage in Rat Retina.

PubMed

Ishihara, Tomoe; Kaidzu, Sachiko; Kimura, Hideto; Koyama, Yasurou; Matsuoka, Yotaro; Ohira, Akihiro

2018-05-10

Retinal tissue is exposed to oxidative stress caused by visible light. Light-damaged rat used in age-related macular degeneration (AMD) studies clarified that antioxidants decrease retinal light damage. Albino rats were exposed to 5000 Lux light for 12 h with oral administration of the polyphenolic compounds fraction (PF) from the seed shells of Japanese horse chestnut (30 mg/kg, 100 mg/kg, and 300 mg/kg body weight: BW). To evaluate the protective effects against light damage, electroretinograms (ERGs), the outer nuclear layer (ONL) thickness, the antioxidant activity of plasma, oxidized retinal lipids, and the detection of apoptosis were examined. To reveal their active compounds, PF were separated into an A-type proanthocyanidin (PAF) and a flavonol O -glycosides fraction. The protective effects of these fractions against light damage were compared by measuring the thickness of the ERGs and ONL. Compared with the negative control, the PF group (100 mg/kg and 300 mg/kg BW) significantly suppressed the decrease of the ERG amplitudes and ONL thickness. PF (300 mg/kg BW) induced the elevation of in vivo antioxidant activity, and the suppression of retinal lipid oxidation. PF administration also suppressed apoptotic cell death. The protective effects against light damage were attributable to the antioxidant activity of PAF. The light-induced damage of retinas was protected by oral administration of PF and PAF. Taken together, these compounds are potentially useful for the prevention of the disease caused by light exposure. The protective effects of retinal damage by light exposure were evaluated using polyphenolic compounds from the seed shells of Japanese horse chestnut ( Aesculus turbinata BLUME) as an antioxidant. Decreases in the electroretinographic amplitude and outer nuclear layer thickness were suppressed by the polyphenolic compounds of the seed shells. Polyphenolic compounds from the seed shells of Japanese horse chestnut inhibited the oxidation of retinal lipids. Highly polymeric A-type proanthocyanidin from the seed shells protected the rat retina from light exposure damage by inhibiting oxidative stress and apoptotic mechanisms.

Laser warning receiver to identify the wavelength and angle of arrival of incident laser light

DOEpatents

Sinclair; Michael B.; Sweatt, William C.

2010-03-23

A laser warning receiver is disclosed which has up to hundreds of individual optical channels each optically oriented to receive laser light from a different angle of arrival. Each optical channel has an optical wedge to define the angle of arrival, and a lens to focus the laser light onto a multi-wavelength photodetector for that channel. Each multi-wavelength photodetector has a number of semiconductor layers which are located in a multi-dielectric stack that concentrates the laser light into one of the semiconductor layers according to wavelength. An electrical signal from the multi-wavelength photodetector can be processed to determine both the angle of arrival and the wavelength of the laser light.

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.

Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

2009-05-01

Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.

Multi-layered fabrication of large area PDMS flexible optical light guide sheets

NASA Astrophysics Data System (ADS)

Green, Robert; Knopf, George K.; Bordatchev, Evgueni V.

2017-02-01

Large area polydimethylsiloxane (PDMS) flexible optical light guide sheets can be used to create a variety of passive light harvesting and illumination systems for wearable technology, advanced indoor lighting, non-planar solar light collectors, customized signature lighting, and enhanced safety illumination for motorized vehicles. These thin optically transparent micro-patterned polymer sheets can be draped over a flat or arbitrarily curved surface. The light guiding behavior of the optical light guides depends on the geometry and spatial distribution of micro-optical structures, thickness and shape of the flexible sheet, refractive indices of the constituent layers, and the wavelength of the incident light. A scalable fabrication method that combines soft-lithography, closed thin cavity molding, partial curing, and centrifugal casting is described in this paper for building thin large area multi-layered PDMS optical light guide sheets. The proposed fabrication methodology enables the of internal micro-optical structures (MOSs) in the monolithic PDMS light guide by building the optical system layer-by-layer. Each PDMS layer in the optical light guide can have the similar, or a slightly different, indices of refraction that permit total internal reflection within the optical sheet. The individual molded layers may also be defect free or micro-patterned with microlens or reflecting micro-features. In addition, the bond between adjacent layers is ensured because each layer is only partially cured before the next functional layer is added. To illustrate the scalable build-by-layers fabrication method a three-layer mechanically flexible illuminator with an embedded LED strip is constructed and demonstrated.

The usage of phase change materials in fire fighter protective clothing: its effect on thermal protection

NASA Astrophysics Data System (ADS)

Zhao, Mengmeng

2017-12-01

The thermal protective performance of the fire fighter protective clothing is of vital importance for fire fighters. In the study fabrics treated by phase change materials (PCMs) were applied in the multi-layered fabrics of the fire fighter protective clothing ensemble. The PCM fabrics were placed at the different layers of the clothing and their thermal protective performance were measured by a TPP tester. Results show that with the application of the PCM fabrics the thermal protection of the multi-layered fabrics was greatly increased. The time to reach a second degree burn was largely reduced. The location of the PCM fabrics at the different layers did not affect much on the thermal protective performance. The higher amount of the PCM adds on, the higher thermal protection was brought. The fabrics with PCMs of a higher melting temperature could contribute to higher thermal protection.

Light Absorption Enhancement of Silicon-Based Photovoltaic Devices with Multiple Bandgap Structures of Porous Silicon

PubMed Central

Wu, Kuen-Hsien; Li, Chong-Wei

2015-01-01

Porous-silicon (PS) multi-layered structures with three stacked PS layers of different porosity were prepared on silicon (Si) substrates by successively tuning the electrochemical-etching parameters in an anodization process. The three PS layers have different optical bandgap energy and construct a triple-layered PS (TLPS) structure with multiple bandgap energy. Photovoltaic devices were fabricated by depositing aluminum electrodes of Schottky contacts on the surfaces of the developed TLPS structures. The TLPS-based devices exhibit broadband photoresponses within the spectrum of the solar irradiation and get high photocurrent for the incident light of a tungsten lamp. The improved spectral responses of devices are owing to the multi-bandgap structures of TLPS, which are designed with a layered configuration analog to a tandem cell for absorbing a wider energy range of the incidental sun light. The large photocurrent is mainly ascribed to an enhanced light-absorption ability as a result of applying nanoporous-Si thin films as the surface layers to absorb the short-wavelength light and to improve the Schottky contacts of devices. Experimental results reveal that the multi-bandgap PS structures produced from electrochemical-etching of Si wafers are potentially promising for development of highly efficient Si-based solar cells. PMID:28793542

Multi-frequency metasurface carpet cloaks.

PubMed

Wang, Chan; Yang, Yihao; Liu, Qianghu; Liang, Dachuan; Zheng, Bin; Chen, Hongsheng; Xu, Zhiwei; Wang, Huaping

2018-05-28

Metasurfaces provide an alternative way to design three-dimensional arbitrary-shaped carpet cloaks with ultrathin thicknesses. Nevertheless, the previous metasurface carpet cloaks work only at a single frequency. To overcome this challenge, we here propose a macroscopic metasurface carpet cloak. The cloak is designed with a metasurface of a few layers that exhibit a special spatial distribution of the conductance and inductance in the unit cell; therefore, it can fully control the reflection phases at several independent frequencies simultaneously. Because of this, the present metasurface cloak can work at dual frequencies based on multi-resonance principle. The proposed design methodology will be very useful in future broadband macroscopic cloaks design with low profiles, light weights, and easy access.

Hazards protection for space suits and spacecraft

NASA Technical Reports Server (NTRS)

Kosmo, Joseph J. (Inventor); Dawn, Frederic S. (Inventor)

1990-01-01

A flexible multi-layered covering article for protection against the hazards of exposure to the environment of outer space is disclosed. The covering includes an outer layer section comprising an outermost lamina of woven expanded tetrafluoroethylene yarns (Gore Tex) for protecting against abrasion and tearing, an underlying weave of meta-aramid yarns (Nomex) and para-aramid yarns (Kevlar) for particle impart protection, and electrostatic charge dissipation and control system incorporated therein, and a chemical contaminants control barrier applied as a coating. A middle section includes a succession of thermal insulating layers of polymeric thermoplastic or thermoforming material, each of which is coated with a metal deposit of high infra-red emissivity and low solar radiation absorption characteristics and separated from adjacent insulating layers by a low thermal conductance material. The covering further includes a radiation attenuating layer of a tungsten-loaded polymeric elastomer binder for protecting against bremsstrahlung radiation and an inner layer of rip-stop polyester material for abrasion protection. A chloroprene coating may be supplied the polyester-material for added micrometeroid protection. Securing means of low heat conductance material secures the multi-layers together as a laminar composite.

Shields for Enhanced Protection Against High-Speed Debris

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Kerr, Justin H.

2003-01-01

A report describes improvements over the conventional Whipple shield (two thin, spaced aluminum walls) for protecting spacecraft against high-speed impacts of orbiting debris. The debris in question arise mainly from breakup of older spacecraft. The improved shields include exterior bumper layers composed of hybrid fabrics woven from combinations of ceramic fibers and high-density metallic wires or, alternatively, completely metallic outer layers composed of high-strength steel or copper wires. These shields are designed to be light in weight, yet capable of protecting against orbital debris with mass densities up to about 9 g/cm3, without generating damaging secondary debris particles. As yet another design option, improved shields can include sparsely distributed wires made of shape-memory metals that can be thermally activated from compact storage containers to form shields of predetermined shape upon arrival in orbit. The improved shields could also be used to augment shields installed previously.

Shields for Enhanced Protection Against High-Speed Debris

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Kerr, Justin H.

2003-01-01

A report describes improvements over the conventional Whipple shield (two thin, spaced aluminum walls) for protecting spacecraft against high-speed impacts of orbiting debris. The debris in question arises mainly from breakup of older spacecraft. The improved shields include exterior "bumper" layers composed of hybrid fabrics woven from combinations of ceramic fibers and high-density metallic wires or, alternatively, completely metallic outer layers composed of high-strength steel or copper wires. These shields are designed to be light in weight, yet capable of protecting against orbital debris with mass densities up to about 9 g/cubic cm, without generating damaging secondary debris particles. As yet another design option, improved shields can include sparsely distributed wires made of shape memory metals that can be thermally activated from compact storage containers to form shields of predetermined shape upon arrival in orbit. The improved shields could also be used to augment shields installed previously.

Cd-free Cu-Zn-In-S/ZnS quantum dots@SiO2 multiple cores nanostructure: preparation and application for white LEDs

NASA Astrophysics Data System (ADS)

Jiang, Tongtong; Shen, Mohan; Dai, Peng; Wu, Mingzai; Yu, Xinxin; Li, Guang; Xu, Xiaoliang; Zeng, Haibo

2017-10-01

The work reports the fabrication of Cu doped Zn-In-S (CZIS) alloy quantum dots (QDs) using dodecanethiol and oleic acid as stabilizing ligands. With the increase of doped Cu element, the photoluminescence (PL) peak is monotonically red shifted. After coating ZnS shell, the PL quantum yield of CZIS QDs can reach 78%. Using reverse micelle microemulsion method, CZIS/ZnS QDs@SiO2 multi-core nanospheres were synthesized to improve the colloidal stability and avoid the aggregation of QDs. The obtained multi-core nanospheres were dispersed in curing adhesive, and applied as a color conversion layer in down converted light-emitting diodes. After encapsulation in curing adhesive, the newly designed LEDs show artifically regulated color coordinates with varying the weight ratio of green QDs and red QDs, and the concentrations of these two types of QDs. Moreover, natural white and warm white LEDs with correlated color temperature of 5287, 6732, 2731, and 3309 K can be achieved, which indicates that CZIS/ZnS QDs@SiO2 nanostructures are promising color conversion layer material for solid-state lighting application.

Design and fabrication of light weight current collectors for direct methanol fuel cells using the micro-electro mechanical system technique

NASA Astrophysics Data System (ADS)

Sung, Min-Feng; Kuan, Yean-Der; Chen, Bing-Xian; Lee, Shi-Min

The direct methanol fuel cell (DMFC) is suitable for portable applications. Therefore, a light weight and small size is desirable. The main objective of this paper is to design and fabricate a light weight current collector for DMFC usage. The light weight current collector mainly consists of a substrate with two thin film metal layers. The substrate of the current collector is an FR4 epoxy plate. The thin film metal layers are accomplished by the thermo coater technique to coat metal powders onto the substrate surfaces. The developed light weight current collectors are further assembled to a single cell DMFC test fixture to measure the cell performance. The results show that the proposed current collectors could even be applied to DMFCs because they are light, thin and low cost and have potential for mass production.

Protecting the surface of a light absorber in a photoanode

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

Hu, Shu; Lewis, Nathan S.

A photoanode includes a passivation layer on a light absorber. The passivation layer is more resistant to corrosion than the light absorber. The photoanode includes a surface modifying layer that is location on the passivation layer such that the passivation layer is between the light absorber and the surface modifying layer. The surface modifying layer reduces a resistance of the passivation layer to conduction of holes out of the passivation layer.

Research on HDR image fusion algorithm based on Laplace pyramid weight transform with extreme low-light CMOS

NASA Astrophysics Data System (ADS)

Guan, Wen; Li, Li; Jin, Weiqi; Qiu, Su; Zou, Yan

2015-10-01

Extreme-Low-Light CMOS has been widely applied in the field of night-vision as a new type of solid image sensor. But if the illumination in the scene has drastic changes or the illumination is too strong, Extreme-Low-Light CMOS can't both clearly present the high-light scene and low-light region. According to the partial saturation problem in the field of night-vision, a HDR image fusion algorithm based on the Laplace Pyramid was researched. The overall gray value and the contrast of the low light image is very low. We choose the fusion strategy based on regional average gradient for the top layer of the long exposure image and short exposure image, which has rich brightness and textural features. The remained layers which represent the edge feature information of the target are based on the fusion strategy based on regional energy. In the process of source image reconstruction with Laplacian pyramid image, we compare the fusion results with four kinds of basal images. The algorithm is tested using Matlab and compared with the different fusion strategies. We use information entropy, average gradient and standard deviation these three objective evaluation parameters for the further analysis of the fusion result. Different low illumination environment experiments show that the algorithm in this paper can rapidly get wide dynamic range while keeping high entropy. Through the verification of this algorithm features, there is a further application prospect of the optimized algorithm. Keywords: high dynamic range imaging, image fusion, multi-exposure image, weight coefficient, information fusion, Laplacian pyramid transform.

Color stable white phosphorescent organic light emitting diodes with red emissive electron transport layer

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

Wook Kim, Jin; Yoo, Seung Il; Sung Kang, Jin

2015-06-28

We analyzed the performance of multi-emissive white phosphorescent organic light-emitting diodes (PHOLEDs) in relation to various red emitting sites of hole and electron transport layers (HTL and ETL). The shift of the recombination zone producing stable white emission in PHOLEDs was utilized as luminance was increased with red emission in its electron transport layer. Multi-emissive white PHOLEDs including the red light emitting electron transport layer yielded maximum external quantum efficiency of 17.4% with CIE color coordinates (−0.030, +0.001) shifting only from 1000 to 10 000 cd/m{sup 2}. Additionally, we observed a reduction of energy loss in the white PHOLED via Ir(piq){submore » 3} as phosphorescent red dopant in electron transport layer.« less

Near-ultraviolet light-emitting diodes with transparent conducting layer of gold-doped multi-layer graphene

NASA Astrophysics Data System (ADS)

Cho, Chu-Young; Choe, Minhyeok; Lee, Sang-Jun; Hong, Sang-Hyun; Lee, Takhee; Lim, Wantae; Kim, Sung-Tae; Park, Seong-Ju

2013-03-01

We report on gold (Au)-doped multi-layer graphene (MLG), which can be used as a transparent conducting layer in near-ultraviolet light-emitting diodes (NUV-LEDs). The optical output power of NUV-LEDs with thermally annealed Au-doped MLG was increased by 34% compared with that of NUV-LEDs with a bare MLG. This result is attributed to the reduced sheet resistance and the enhanced current injection efficiency of NUV-LEDs by the thermally annealed Au-doped MLG film, which shows high transmittance in NUV and UV regions and good adhesion of Au-doped MLG on p-GaN layer of NUV-LEDs.

78 FR 75913 - Final Tank Closure and Waste Management Environmental Impact Statement for the Hanford Site...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-13

... Subtitle C barrier, a multi-layer barrier designed to provide 500-year protection. \\2\\ Under Tank Closure..., which means the tanks, ancillary equipment, and contaminated soil would be removed, and the remaining... Hanford barrier, a multi- layer barrier designed to provide 1,000-year protection. Alternative 6: All...

Corrosion protected, multi-layer fuel cell interface

DOEpatents

Feigenbaum, Haim; Pudick, Sheldon; Wang, Chiu L.

1986-01-01

An improved interface configuration for use between adjacent elements of a fuel cell stack. The interface is impervious to gas and liquid and provides resistance to corrosion by the electrolyte of the fuel cell. The multi-layer configuration for the interface comprises a non-cupreous metal-coated metallic element to which is film-bonded a conductive layer by hot pressing a resin therebetween. The multi-layer arrangement provides bridging electrical contact.

Soil Transport Implement

NASA Technical Reports Server (NTRS)

Dixon, William; Fan, William; Lloyd, Joey; Pham, Nam-Anh; Stevens, Michael

1988-01-01

The design of the Soil Transport Implement (STI) for SKITTER is presented. The purpose of STI is to provide a protective layer of lunar soil for the lunar modules. The objective is to cover the lunar module with a layer of soil approximately two meters thick within a two week period. The amount of soil required to cover the module is roughly 77 dump truck loads or three million earth pounds. A spinning disk is employed to accomplish its task. STI is an autonomous, teleoperated system. The design incorporates the latest advances in composite materials and high strength, light weight alloys to achieve a high strength to weight ratio. The preliminary design should only be used to assess the feasibility of employing a spinning wheel as a soil transport implement. A mathematical model of the spinning wheel was used to evaluate the performance of this design.

MULPEX: A compact multi-layered polymer foil collector for micrometeoroids and orbital debris

NASA Astrophysics Data System (ADS)

Kearsley, A. T.; Graham, G. A.; Burchell, M. J.; Taylor, E. A.; Drolshagen, G.; Chater, R. J.; McPhail, D.

Detailed studies of preserved hypervelocity impact residues on spacecraft multi-layer insulation foils have yielded important information about the flux of small particles from different sources in low-Earth orbit (LEO). We have extended our earlier research on impacts occurring in LEO to design and testing of a compact capture device. MUlti- Layer Polymer EXperiment (MULPEX) is simple, cheap to build, lightweight, of no power demand, easy to deploy, and optimised for the efficient collection of impact residue for analysis on return to Earth. The capture medium is a stack of very thin (8 and 40 μm) polyimide foils, supported on poly-tetrafluoroethylene sheet frames, surrounded by a protective aluminium casing. The uppermost foil has a very thin metallic coating for thermal protection and resistance to atomic oxygen and ultra-violet exposure. The casing provides a simple detachable interface for deployment on the spacecraft, facing into the desired direction for particle collection. On return to the laboratory, the stacked foils are separated for examination in a variable pressure scanning electron microscope, without need for surface coating. Analysis of impact residue is performed using energy dispersive X-ray spectrometers. Our laboratory experiments, utilising buck-shot firings of analogues to micrometeoroids (35-38 μm olivine) and space debris (4 μm alumina and 1 mm stainless steel) in a light gas gun, have shown that impact residue is abundant within the foil layers, and preserves a record of the impacting particle, whether of micrometer or millimetre dimensions. Penetrations of the top foil are easily recognised, and act as a proxy for dimensions of the penetrating particle. Impact may cause disruption and melting, but some residue retains sufficient crystallographic structure to show clear Raman lines, diagnostic of the original mineral.

MULPEX: a compact multi-layered polymer foil collector for micrometeoroids and orbital debris.

NASA Astrophysics Data System (ADS)

Kearsley, A. T.; Graham, G. A.; Burchell, M. J.; Taylor, E. A.; Drolshagen, G.; Chater, R. J.; McPhail, D.

Detailed studies of preserved hypervelocity impact residues on spacecraft multi-layer insulation foils have yielded important information about the flux of small particles from different sources in low-Earth orbit (LEO). We have extended our earlier research on impacts occurring in LEO to design and testing of a compact capture device. MULPEX (MUlti-Layer Polymer EXperiment) is simple, cheap to build, lightweight, of no power demand, easy to deploy, and optimised for the efficient collection of impact residue for analysis on return to Earth. The capture medium is a stack of very thin (8 micron and 40 micron) polyimide foils, supported on poly-tetrafluoroethylene sheet frames, surrounded by a protective aluminium casing. The uppermost foil has a very thin metallic coating for thermal protection and resistance to atomic oxygen and ultra-violet exposure. The casing provides a simple detachable interface for deployment on the spacecraft, facing into the desired direction for particle collection. On return to the laboratory, the stacked foils are separated for examination in a variable pressure scanning electron microscope, without need for surface coating. Analysis of impact residue is performed using energy dispersive X-ray spectrometers. Our laboratory experiments, utilising buck-shot firings of analogues to micrometeoroids (35-38 micron olivine) and space debris (4 micron alumina and 1mm stainless steel) in a light gas gun, have shown that impact residue is abundant within the foil layers, and preserves a record of the impacting particle, whether of micrometer or millimetre dimensions. Penetrations of the top foil are easily recognised, and act as a proxy for dimensions of the penetrating particle. Impact may cause disruption and melting, but some residue retains sufficient crystallographic structure to show clear Raman lines, diagnostic of the original mineral.

Multi-clad black display panel

DOEpatents

Veligdan, James T.; Biscardi, Cyrus; Brewster, Calvin

2002-01-01

A multi-clad black display panel, and a method of making a multi-clad black display panel, are disclosed, wherein a plurality of waveguides, each of which includes a light-transmissive core placed between an opposing pair of transparent cladding layers and a black layer disposed between transparent cladding layers, are stacked together and sawed at an angle to produce a wedge-shaped optical panel having an inlet face and an outlet face.

Use of falling weight deflectometer multi-load data for pavement strength estimation

DOT National Transportation Integrated Search

2002-06-01

The objective of this study is to develop a mechanistic-empirical method for assessing pavement layer conditions and : estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A : dyna...

Effects of UV Aging on the Cracking of Titanium Oxide Layer on Poly(ethylene terephthalate) Substrate: Preprint

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

Zhang, Chao; Gray, Matthew H.; Tirawat, Robert

Thin oxide and metal films deposited on polymer substrates is an emerging technology for advanced reflectors for concentrated solar power applications, due to their unique combination of light weight, flexibility and inexpensive manufacture. Thus far, there is little knowledge on the mechanical integrity or structural persistence of such multi-layer thin film systems under long-term environmental aging. In this paper, the cracking of a brittle titanium dioxide layer deposited onto elasto-plastic poly(ethylene terephthalate) (PET) substrate is studied through a combination of experiment and modeling. In-situ fragmentation tests have been conducted to monitor the onset and evolution of cracks both on pristinemore » and on samples aged with ultraviolet (UV) light. An analytical model is presented to simulate the cracking behavior and to predict the effects of UV aging. Based on preliminary experimental observation, the effect of aging is divided into three aspects and analyzed independently: mechanical property degradation of the polymer substrate; degradation of the interlayer between substrate and oxide coating; and internal stress-induced cracks on the oxide coating.« less

Light emitting ceramic device

DOEpatents

Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

2010-05-18

A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

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.

Properties of Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Kang, Jin Ho; Grimsley, Brian W.; Ratcliffe, James G.; Siochi, Emilie J.

2016-01-01

For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strength- and stiffness-to-weight ratios, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Carbon nanotubes (CNT) offer the potential to enhance the multi-functionality of composites with improved thermal and electrical conductivity. In this study, hybrid CNT/carbon fiber (CF) polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing. Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated.

Engendering Long-Term Air and Light Stability of a TiO2-Supported Porphyrinic Dye via Atomic Layer Deposition.

PubMed

Hoffeditz, William L; Son, Ho-Jin; Pellin, Michael J; Farha, Omar K; Hupp, Joseph T

2016-12-21

Organic and porphyrin-based chromophores are prevalent in liquid-junction photovoltaic and photocatalytic solar-cell chemistry; however, their long-term air and light instability may limit their practicality in real world technologies. Here, we describe the protection of a zinc porphyrin dye, adsorbed on nanoparticulate TiO 2 , from air and light degradation by a protective coating of alumina grown with a previously developed post-treatment atomic layer deposition (ALD) technique. The protective Al 2 O 3 ALD layer is deposited using dimethylaluminum isopropoxide as an Al source; in contrast to the ubiquitous ALD precursor trimethylaluminum, dimethylaluminum isopropoxide does not degrade the zinc porphyrin dye, as confirmed by UV-vis measurements. The growth of this protective ALD layer around the dye can be monitored by an in-reactor quartz crystal microbalance (QCM). Furthermore, greater than 80% of porphyrin light absorption is retained over ∼1 month of exposure to air and light when the protective coating is present, whereas almost complete loss of porphyrin absorption is observed in less than 2 days in the absence of the ALD protective layer. Applying the Al 2 O 3 post-treatment technique to the TiO 2 -adsorbed dye allows the dye to remain in electronic contact with both the semiconductor surface and a surrounding electrolyte solution, the combination of which makes this technique promising for numerous other electrochemical photovoltaic and photocatalytic applications, especially those involving the dye-sensitized evolution of oxygen.

Monte Carlo modeling (MCML) of light propagation in skin layers for detection of fat thickness

NASA Astrophysics Data System (ADS)

Nilubol, Chonnipa; Treerattrakoon, Kiatnida; Mohammed, Waleed S.

2010-05-01

Nowadays, most activities require lesser physical actions, which could ultimately lead to accumulation of excessive body fat. The main roles of body fat are to store energy and acts as various kinds of insulators for the body. The thickness of fat layers can be measured to indicate fat-body weight ratio. Exceeding the body-mass index (BMI) could lead to many illnesses regarding obesity. Consequently, many studies have proposed various principles and techniques to measure the amount of fat within one's body. In this paper, infrared interactance in skin layers is studied for investigation of the influence of fat thickness upon photon travelling pattern in skin tissues using Monte Carlo model (MCML). Photon propagation is numerically simulated in simplified multi-layered tissues. The optical coefficients of each skin layers are accounted for different traveling paths of photons that move through random motion. The thickness of fat layer is varied, and changing in optical parameters is observed. Then the statistically obtained data are computed and analyzed for the effect of the fat layer upon reflection percentage using different wavelengths. The calculations have shown increment in the slope of change of reflection percentage versus fat thickness, when using infrared compare to visible light. This technique can be used to construct a mobile device that is capable of measuring the volume fraction of melanin and blood in the epidermis layer and dermis layer, to calculate for the necessary optical coefficients that would be necessary for measurement of fat thickness.

Article having an improved platinum-aluminum-hafnium protective coating

NASA Technical Reports Server (NTRS)

Nagaraj, Bangalore Aswatha (Inventor); Williams, Jeffrey Lawrence (Inventor)

2005-01-01

An article protected by a protective coating has a substrate and a protective coating having an outer layer deposited upon the substrate surface and a diffusion zone formed by interdiffusion of the outer layer and the substrate. The protective coating includes platinum, aluminum, no more than about 2 weight percent hafnium, and substantially no silicon. The outer layer is substantially a single phase.

Light emitting ceramic device and method for fabricating the same

DOEpatents

Valentine, Paul; Edwards, Doreen D.; Walker Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

2004-11-30

A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, and alternative methods of fabrication for the same are claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

The Effects of Light Intensity, Casing Layers, and Layering Styles on Royal Sun Medicinal Mushroom, Agaricus brasiliensis (Higher Basidiomycetes) Cultivation in Turkey.

PubMed

Adanacioglu, Neşe; Boztok, Kaya; Akdeniz, Ramazan Cengiz

2015-01-01

The aim of this research is to evaluate the effects of light intensity, casing layers, and layering styles on the production of the culinary-medicinal mushroom Agaricus brasiliensis in Turkey. The experiments were designed in split-split plots and replicated twice. Three different light intensities-I1, 350 lux; I2, 450 lux; and I3, 750 lux-were used in main plots as environmental factors. A mixture of 4 different casing layers- peat (100%), peat-perlite (75%:25%), peat-clinoptilolite (75%:25%), and peat-perlite-clinoptilolite (60%:20%:20%)-were used at split plots and at split plots. S1, a flat, 3-cm casing layer; S2, a flat, 5-cm casing layer; and S3, casing soil ridges 10 cm wide × 4 cm high, 10 cm apart, were deposited on top of 1-cm overall soil casing layers. At the end of the harvest phase, the total yield was estimated per 100 kg of substrate. Biological efficiency (percentage) was determined from the fresh weight of the mushrooms and the dry weight of the compost at the end of the harvesting period. The highest total yield (7.2 kg/100 kg compost) and biological efficiency (27.63%) were achieved from I2 × peat-perlite-clinoptilolite × S2 treatment. Influence of light intensity, casing layer, layering style, and their interaction in treatments with color values (L*, a*, b*, chroma*, and hue*) also were examined. It has been shown that within color values, chroma* (saturation) values of mushroom caps were affected by light intensity, casing layer, and layering style treatments and light intensity × casing layer treatments and the brightness of mushroom caps tended to increase as light intensity increased.

Preparation of multi-layer film consisting of hydrogen-free DLC and nitrogen-containing DLC for conductive hard coating

NASA Astrophysics Data System (ADS)

Iijima, Yushi; Harigai, Toru; Isono, Ryo; Degai, Satoshi; Tanimoto, Tsuyoshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Yasui, Haruyuki; Kaneko, Satoru; Kunitsugu, Shinsuke; Kamiya, Masao; Taki, Makoto

2018-01-01

Conductive hard-coating films have potential application as protective films for contact pins used in the electrical inspection process for integrated circuit chips. In this study, multi-layer diamond-like carbon (DLC) films were prepared as conductive hard-coating films. The multi-layer DLC films consisting of DLC and nitrogen-containing DLC (N-DLC) film were prepared using a T-shape filtered arc deposition method. Periodic DLC/N-DLC four-layer and eight-layer films had the same film thickness by changing the thickness of each layer. In the ball-on-disk test, the N-DLC mono-layer film showed the highest wear resistance; however, in the spherical polishing method, the eight-layer film showed the highest polishing resistance. The wear and polishing resistance and the aggressiveness against an opponent material of the multi-layer DLC films improved by reducing the thickness of a layer. In multi-layer films, the soft N-DLC layer between hard DLC layers is believed to function as a cushion. Thus, the tribological properties of the DLC films were improved by a multi-layered structure. The electrical resistivity of multi-layer DLC films was approximately half that of the DLC mono-layer film. Therefore, the periodic DLC/N-DLC eight-layer film is a good conductive hard-coating film.

Embedding Carbon Fibre Structures in Metal Matrixes for Additive Manufacturing

NASA Astrophysics Data System (ADS)

Frostevarg, Jan; Robertson, Stephanie; Benavides, Vicente; Soldatov, Alexander

It is possible to reinforce structures and components using carbon fibres for applications in electronics and medicine, but most commonly used in reinforcing resin fibre composites for personal protection equipment and light weight constructions. Carbon fibres act as stress redistributors while having increased electrical and thermal conductivities. These properties could also be utilized in metal matrixes, if the fibres are properly fused to the metal and the structure remains intact. Another recently developed high potential carbon structure, carbon nanotube- (CNT) yarns, has similar but even greater mechanical properties than common carbon fibres. Via laser cladding, these reinforcing materials could be used in a plethora of applications, either locally (or globally) as surface treatments or as structural reinforcements using multi-layer laser cladding (additive manufacturing). The challenges of embedding carbon fibres or CNT-yarns in a CuAl mixture and SnPb solder wire using lasers are here investigated using high speed imaging and SEM. It is revealed that the carbon fibres have very high buoyancy in the molten metal and quickly degrades when irradiated by the laser. Wetting of the fibres is shown to be improved by a Tungsten coating and embedding of the structures after processing are evaluated using SEM and Raman spectroscopy.

Laser penetration spike welding: a welding tool enabling novel process and design opportunities

NASA Astrophysics Data System (ADS)

Dijken, Durandus K.; Hoving, Willem; De Hosson, J. Th. M.

2002-06-01

A novel method for laser welding for sheet metal. is presented. This laser spike welding method is capable of bridging large gaps between sheet metal plates. Novel constructions can be designed and manufactured. Examples are light weight metal epoxy multi-layers and constructions having additional strength with respect to rigidity and impact resistance. Its capability to bridge large gaps allows higher dimensional tolerances in production. The required laser systems are commercially available and are easily implemented in existing production lines. The lasers are highly reliable, the resulting spike welds are quickly realized and the cost price per weld is very low.

Light source distribution and scattering phase function influence light transport in diffuse multi-layered media

NASA Astrophysics Data System (ADS)

Vaudelle, Fabrice; L'Huillier, Jean-Pierre; Askoura, Mohamed Lamine

2017-06-01

Red and near-Infrared light is often used as a useful diagnostic and imaging probe for highly scattering media such as biological tissues, fruits and vegetables. Part of diffusively reflected light gives interesting information related to the tissue subsurface, whereas light recorded at further distances may probe deeper into the interrogated turbid tissues. However, modelling diffusive events occurring at short source-detector distances requires to consider both the distribution of the light sources and the scattering phase functions. In this report, a modified Monte Carlo model is used to compute light transport in curved and multi-layered tissue samples which are covered with a thin and highly diffusing tissue layer. Different light source distributions (ballistic, diffuse or Lambertian) are tested with specific scattering phase functions (modified or not modified Henyey-Greenstein, Gegenbauer and Mie) to compute the amount of backscattered and transmitted light in apple and human skin structures. Comparisons between simulation results and experiments carried out with a multispectral imaging setup confirm the soundness of the theoretical strategy and may explain the role of the skin on light transport in whole and half-cut apples. Other computational results show that a Lambertian source distribution combined with a Henyey-Greenstein phase function provides a higher photon density in the stratum corneum than in the upper dermis layer. Furthermore, it is also shown that the scattering phase function may affect the shape and the magnitude of the Bidirectional Reflectance Distribution (BRDF) exhibited at the skin surface.

Monitoring Natural World Heritage Sites: optimization of the monitoring system in Bogda with GIS-based multi-criteria decision analysis.

PubMed

Wang, Zhaoguo; Du, Xishihui

2016-07-01

Natural World Heritage Sites (NWHSs) are invaluable treasure due to the uniqueness of each site. Proper monitoring and management can guarantee their protection from multiple threats. In this study, geographic information system (GIS)-based multi-criteria decision analysis (GIS-MCDA) was used to assess criteria layers acquired from the data available in the literature. A conceptual model for determining the priority area for monitoring in Bogda, China, was created based on outstanding universal values (OUV) and expert knowledge. Weights were assigned to each layer using the analytic hierarchy process (AHP) based on group decisions, encompassing three experts: one being a heritage site expert, another a forest ranger, and the other a heritage site manager. Subsequently, evaluation layers and constraint layers were used to generate a priority map and to determine the feasibility of monitoring in Bogda. Finally, a monitoring suitability map of Bogda was obtained by referencing priority and feasibility maps.The high-priority monitoring area is located in the montane forest belt, which exhibits high biodiversity and is the main tourist area of Bogda. The northern buffer zone of Bogda comprises the concentrated feasible monitoring areas, and the area closest to roads and monitoring facilities is highly feasible for NWHS monitoring. The suitability of an area in terms of monitoring is largely determined by the monitoring priority in that particular area. The majority of planned monitoring facilities are well distributed in both suitable and less suitable areas. Analysis results indicate that the protection of Bogda will be more scientifically based due to its effective and all-around planned monitoring system proposed by the declaration text of Xinjiang Tianshan, which is the essential file submitted to World Heritage Centre to inscribe as a NWHS.

Thin film solar energy collector

DOEpatents

Aykan, Kamran; Farrauto, Robert J.; Jefferson, Clinton F.; Lanam, Richard D.

1983-11-22

A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

IADC Vulnerability Report, IT32-21

NASA Technical Reports Server (NTRS)

Christiansen, E. L.; Miller, J. E.; Hyde, J.

2016-01-01

Numerous mission support hardware systems and their spares are maintained outside of the habitable volume of the International Space Station (ISS), and are arranged covered by a multi-layer insulation (MLI) thermal blanket which provides both thermal control and a measure of protection from micrometeoroids and orbital debris (MMOD). The NASA Hypervelocity Impact Technology (HVIT) group at the Johnson Space Center in Houston Texas has assessed the protection provided by MLI in a series of hypervelocity impact tests using a 1 mm thick aluminum 6061-T6 rear wall to simulate the actual hardware behind the MLI. HVIT has also evaluated methods to enhance the protection provided by MLI thermal blankets. The impact study used both aluminum and steel spherical projectiles accelerated to speeds of 7 km/s using a 4.3 mm, two-stage, light-gas gun at the NASA White Sands Test Facility (WSTF).

Light intensity and quality from sole-source light-emitting diodes impact growth, morphology, and nutrient content of Brassica microgreens

USDA-ARS?s Scientific Manuscript database

Multi-layer vertical production systems using sole-source (SS) lighting can be used for microgreen production; however, traditional SS lighting can consume large amounts of electrical energy. Light-emitting diodes (LEDs) offer many advantages over conventional light sources including: high photoelec...

Light dosimetry for focused and defocused beam irradiation in multi-layered tissue models

NASA Astrophysics Data System (ADS)

Petrova, Kremena S.; Stoykova, Elena V.

2006-09-01

Treatment of acupuncture points, trigger points, joint inflammations in low level laser therapy as well as various applications of lasers for treatment of soft tissues in dental medicine, require irradiation by a narrow converging laser beam. The aim of this study is to compare light delivery produced by focused or defocused narrow beam irradiation in a multi-layered skin tissue model at increasing depth of the target. The task is solved by 3-D Monte-Carlo simulation for matched and mismatched refractive indices at the tissue/ambient medium interface. The modeled light beams have a circular cross-section at the tissue entrance with uniform or Gaussian intensity distribution. Three are the tissue models used in simulation : i) a bloodless skin layer; ii) a bloodless skin layer with embedded scattering object; iii) a skin layer with small blood vessels of varying size, which are modeled as infinite cylinders parallel to the tissue surface located at different depths. Optical properties (absorption coefficient, scattering coefficient, anisotropy factor, g, and index of refraction) of different tissue constituents are chosen from the literature.

Effect of frequency on fretting wear behavior of Ti/TiN multilayer film on depleted uranium

PubMed Central

Zhu, Sheng-Fa; Lu, Lei; Cai, Zhen-Bing

2017-01-01

The Ti/TiN multi-layer film was prepared on the depleted uranium (DU) substrate by cathodic arc ion plating equipment. The character of multi-layer film was studied by SEM, XRD and AES, revealed that the surface was composed of small compact particle and the cross-section had a multi-layer structure. The fretting wear performance under different frequencies was performed by a MFT-6000 machine with a ball-on-plate configuration. The wear morphology was analyzed by white light interferometer, OM and SEM with an EDX. The result shows the Ti/TiN multi-layer film could greatly improve the fretting wear performance compared to the DU substrate. The fretting wear running and damaged behavior are strongly dependent on the film and test frequency. The fretting region of DU substrate and Ti/TiN multi-layer under low test frequency is gross slip. With the increase of test frequency, the fretting region of Ti/TiN multi-layer change from gross slip to mixed fretting, then to partial slip. PMID:28384200

Effect of frequency on fretting wear behavior of Ti/TiN multilayer film on depleted uranium.

PubMed

Wu, Yan-Ping; Li, Zheng-Yang; Zhu, Sheng-Fa; Lu, Lei; Cai, Zhen-Bing

2017-01-01

The Ti/TiN multi-layer film was prepared on the depleted uranium (DU) substrate by cathodic arc ion plating equipment. The character of multi-layer film was studied by SEM, XRD and AES, revealed that the surface was composed of small compact particle and the cross-section had a multi-layer structure. The fretting wear performance under different frequencies was performed by a MFT-6000 machine with a ball-on-plate configuration. The wear morphology was analyzed by white light interferometer, OM and SEM with an EDX. The result shows the Ti/TiN multi-layer film could greatly improve the fretting wear performance compared to the DU substrate. The fretting wear running and damaged behavior are strongly dependent on the film and test frequency. The fretting region of DU substrate and Ti/TiN multi-layer under low test frequency is gross slip. With the increase of test frequency, the fretting region of Ti/TiN multi-layer change from gross slip to mixed fretting, then to partial slip.

Distributed Grooming in Multi-Domain IP/MPLS-DWDM Networks

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

Liu, Qing

2009-12-01

This paper studies distributed multi-domain, multilayer provisioning (grooming) in IP/MPLS-DWDM networks. Although many multi-domain studies have emerged over the years, these have primarily considered 'homogeneous' network layers. Meanwhile, most grooming studies have assumed idealized settings with 'global' link state across all layers. Hence there is a critical need to develop practical distributed grooming schemes for real-world networks consisting of multiple domains and technology layers. Along these lines, a detailed hierarchical framework is proposed to implement inter-layer routing, distributed grooming, and setup signaling. The performance of this solution is analyzed in detail using simulation studies and future work directions are alsomore » high-lighted.« less

Recent progress in photoactive organic field-effect transistors.

PubMed

Wakayama, Yutaka; Hayakawa, Ryoma; Seo, Hoon-Seok

2014-04-01

Recent progress in photoactive organic field-effect transistors (OFETs) is reviewed. Photoactive OFETs are divided into light-emitting (LE) and light-receiving (LR) OFETs. In the first part, LE-OFETs are reviewed from the viewpoint of the evolution of device structures. Device performances have improved in the last decade with the evolution of device structures from single-layer unipolar to multi-layer ambipolar transistors. In the second part, various kinds of LR-OFETs are featured. These are categorized according to their functionalities: phototransistors, non-volatile optical memories, and photochromism-based transistors. For both, various device configurations are introduced: thin-film based transistors for practical applications, single-crystalline transistors to investigate fundamental physics, nanowires, multi-layers, and vertical transistors based on new concepts.

Influences of wide-angle and multi-beam interference on the chromaticity and efficiency of top-emitting white organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Deng, Lingling; Zhou, Hongwei; Chen, Shufen; Shi, Hongying; Liu, Bin; Wang, Lianhui; Huang, Wei

2015-02-01

Wide-angle interference (WI) and multi-beam interference (MI) in microcavity are analyzed separately to improve chromaticity and efficiency of the top-emitting white organic light-emitting diodes (TWOLEDs). A classic electromagnetic theory is used to calculate the resonance intensities of WI and MI in top-emitting organic light-emitting diodes (TOLEDs) with influence factors (e.g., electrodes and exciton locations) being considered. The role of WI on the performances of TOLEDs is revealed through using δ-doping technology and comparing blue and red EML positions in top-emitting and bottom-emitting devices. The blue light intensity significantly increases and the chromaticity of TWOLEDs is further improved with the use of enhanced WI (the blue emitting layer moving towards the reflective electrode) in the case of a weak MI. In addition, the effect of the thicknesses of light output layer and carrier transport layers on WI and MI are also investigated. Apart from the microcavity effect, other factors, e.g., carrier balance and carrier recombination regions are considered to obtain TWOLEDs with high efficiency and improved chromaticity near white light equal-energy point.

Influences of wide-angle and multi-beam interference on the chromaticity and efficiency of top-emitting white organic light-emitting diodes

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

Deng, Lingling; Zhou, Hongwei; Chen, Shufen, E-mail: iamsfchen@njupt.edu.cn

Wide-angle interference (WI) and multi-beam interference (MI) in microcavity are analyzed separately to improve chromaticity and efficiency of the top-emitting white organic light-emitting diodes (TWOLEDs). A classic electromagnetic theory is used to calculate the resonance intensities of WI and MI in top-emitting organic light-emitting diodes (TOLEDs) with influence factors (e.g., electrodes and exciton locations) being considered. The role of WI on the performances of TOLEDs is revealed through using δ-doping technology and comparing blue and red EML positions in top-emitting and bottom-emitting devices. The blue light intensity significantly increases and the chromaticity of TWOLEDs is further improved with the usemore » of enhanced WI (the blue emitting layer moving towards the reflective electrode) in the case of a weak MI. In addition, the effect of the thicknesses of light output layer and carrier transport layers on WI and MI are also investigated. Apart from the microcavity effect, other factors, e.g., carrier balance and carrier recombination regions are considered to obtain TWOLEDs with high efficiency and improved chromaticity near white light equal-energy point.« less

Soft epidermis of a scaleless snake lacks beta-keratin.

PubMed

Toni, M; Alibardi, L

2007-01-01

Beta-keratins are responsible for the mechanical resistance of scales in reptiles. In a scaleless crotalus snake (Crotalus atrox), large areas of the skin are completely devoid of scales, and the skin appears delicate and wrinkled. The epidermis of this snake has been assessed for the presence of beta-keratin by immunocytochemistry and immunoblotting using an antibody against chicken scale beta-keratin. This antibody recognizes beta-keratins in normal snake scales with molecular weights of 15-18 kDa and isoelectric points at 6.8, 7.5, 8.3 and 9.4. This indicates that beta-keratins of the stratum corneum are mainly basic proteins, so may interact with cytokeratins of the epidermis, most of which appear acidic (isoelectric points 4.5-5.5). A beta-layer and beta-keratin immunoreactivity are completely absent in moults of the scaleless mutant, and the corneous layer comprises a multi-layered alpha-layer covered by a flat oberhautchen. In conclusion, the present study shows that a lack of beta-keratins is correlated with the loss of scales and mechanical protection in the skin of this mutant snake.

Enhancement of growth and lipid production from microalgae using fluorescent paint under the solar radiation.

PubMed

Seo, Yeong Hwan; Cho, Changsoon; Lee, Jung-Yong; Han, Jong-In

2014-12-01

Solar radiation has intensity that is too high to inhibit microalgae activity and is composed of wide light spectrum including ultraviolet (UV) range which cannot be utilized for microalgae. For these reasons, the modification of solar radiation is required for effective microalgae cultivation, and to do that, fluorescent paint was used for not only blocking excessive solar energy but also converting UV to visible light. With fluorescent aqueous layer, microalgae was protected from photoinhibition and could grow well, but there was difference in growth and lipid accumulation efficiencies depending on the color; maximum dry weight of 1.7 g/L was achieved in red paint, whereas best lipid content of 30% was obtained in blue one. This phenomenon was due to the different light spectrum made by colors. With simple process using fluorescent paint, modification of light was successfully done and allowing microalgae to grow under strong radiation such as solar radiation. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Weld Position Recognition Method Based on Directional and Structured Light Information Fusion in Multi-Layer/Multi-Pass Welding.

PubMed

Zeng, Jinle; Chang, Baohua; Du, Dong; Wang, Li; Chang, Shuhe; Peng, Guodong; Wang, Wenzhu

2018-01-05

Multi-layer/multi-pass welding (MLMPW) technology is widely used in the energy industry to join thick components. During automatic welding using robots or other actuators, it is very important to recognize the actual weld pass position using visual methods, which can then be used not only to perform reasonable path planning for actuators, but also to correct any deviations between the welding torch and the weld pass position in real time. However, due to the small geometrical differences between adjacent weld passes, existing weld position recognition technologies such as structured light methods are not suitable for weld position detection in MLMPW. This paper proposes a novel method for weld position detection, which fuses various kinds of information in MLMPW. First, a synchronous acquisition method is developed to obtain various kinds of visual information when directional light and structured light sources are on, respectively. Then, interferences are eliminated by fusing adjacent images. Finally, the information from directional and structured light images is fused to obtain the 3D positions of the weld passes. Experiment results show that each process can be done in 30 ms and the deviation is less than 0.6 mm. The proposed method can be used for automatic path planning and seam tracking in the robotic MLMPW process as well as electron beam freeform fabrication process.

Lifetime Improvement of Organic Light Emitting Diodes using LiF Thin Film and UV Glue Encapsulation

NASA Astrophysics Data System (ADS)

Huang, Jian-Ji; Su, Yan-Kuin; Chang, Ming-Hua; Hsieh, Tsung-Eong; Huang, Bohr-Ran; Wang, Shun-Hsi; Chen, Wen-Ray; Tsai, Yu-Sheng; Hsieh, Huai-En; Liu, Mark O.; Juang, Fuh-Shyang

2008-07-01

This work demonstrates the use of lithium fluoride (LiF) as a passivation layer and a newly developed UV glue for encapsulation on the LiF passivation layer to enhance the stability of organic light-emitting devices (OLEDs). Devices with double protective layers showed a 25-fold increase in operational lifetime compared to those without any packaging layers. LiF has a low melting point and insulating characteristics and it can be adapted as both a protective layer and pre-encapsulation film. The newly developed UV glue has a fast curing time of only 6 s and can be directly spin-coated onto the surface of the LiF passivation layer. The LiF thin film plus spin-coated UV glue is a simple packaging method that reduces the fabrication costs of OLEDs.

Chemically exfoliating large sheets of phosphorene via choline chloride urea viscosity-tuning

NASA Astrophysics Data System (ADS)

Ng, A.; Sutto, T. E.; Matis, B. R.; Deng, Y.; Ye, P. D.; Stroud, R. M.; Brintlinger, T. H.; Bassim, N. D.

2017-04-01

Exfoliation of two-dimensional phosphorene from bulk black phosphorous through chemical means is demonstrated where the solvent system of choice (choline chloride urea diluted with ethanol) has the ability to successfully exfoliate large-area multi-layer phosphorene sheets and further protect the flakes from ambient degradation. The intercalant solvent molecules, aided by low-powered sonication, diffuse between the layers of the bulk black phosphorus, allowing for the exfoliation of the multi-layer phosphorene through breaking of the interlayer van der Waals bonds. Through viscosity tuning, the optimal parameters (1:1 ratio between the intercalant and the diluting solvent) at which the exfoliation takes place is determined. Our exfoliation technique is shown to produce multi-layer phosphorene flakes with surface areas greater than 3 μm2 (a factor of three larger than what has previously been reported for a similar exfoliation method) while limiting exposure to the ambient environment, thereby protecting the flakes from degradation. Characterization techniques such as optical microscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, and (scanning) transmission electron microscopy are used to investigate the quality, quantity, and thickness of the exfoliated flakes.

High conductivity and transparent aluminum-based multi-layer source/drain electrodes for thin film transistors

NASA Astrophysics Data System (ADS)

Yao, Rihui; Zhang, Hongke; Fang, Zhiqiang; Ning, Honglong; Zheng, Zeke; Li, Xiaoqing; Zhang, Xiaochen; Cai, Wei; Lu, Xubing; Peng, Junbiao

2018-02-01

In this study, high conductivity and transparent multi-layer (AZO/Al/AZO-/Al/AZO) source/drain (S/D) electrodes for thin film transistors were fabricated via conventional physical vapor deposition approaches, without toxic elements or further thermal annealing process. The 68 nm-thick multi-layer films with excellent optical properties (transparency: 82.64%), good electrical properties (resistivity: 6.64  ×  10-5 Ω m, work function: 3.95 eV), and superior surface roughness (R q   =  0.757 nm with scanning area of 5  ×  5 µm2) were fabricated as the S/D electrodes. Significantly, comprehensive performances of AZO films are enhanced by the insertion of ultra-thin Al layers. The optimal transparent TFT with this multi-layer S/D electrodes exhibited a decent electrical performance with a saturation mobility (µ sat) of 3.2 cm2 V-1 s-1, an I on/I off ratio of 1.59  ×  106, a subthreshold swing of 1.05 V/decade. The contact resistance of AZO/Al/AZO/Al/AZO multi-layer electrodes is as low as 0.29 MΩ. Moreover, the average visible light transmittance of the unpatterned multi-layers constituting a whole transparent TFT could reach 72.5%. The high conductivity and transparent multi-layer S/D electrodes for transparent TFTs possessed great potential for the applications of the green and transparent displays industry.

Hypervelocity Impact Experiments on Epoxy/Ultra-High Molecular Weight Polyethylene Composite Panels Reinforced with Nanotubes

NASA Technical Reports Server (NTRS)

Khatiwada, Suman; Laughman, Jay W.; Armada, Carlos A.; Christiansen, Eric L.; Barrera, Enrique V.

2012-01-01

Advanced composites with multi-functional capabilities are of great interest to the designers of aerospace structures. Polymer matrix composites (PMCs) reinforced with high strength fibers provide a lightweight and high strength alternative to metals and metal alloys conventionally used in aerospace architectures. Novel reinforcements such as nanofillers offer potential to improve the mechanical properties and add multi-functionality such as radiation resistance and sensing capabilities to the PMCs. This paper reports the hypervelocity impact (HVI) test results on ultra-high molecular weight polyethylene (UHMWPE) fiber composites reinforced with single-walled carbon nanotubes (SWCNT) and boron nitride nanotubes (BNNT). Woven UHMWPE fabrics, in addition to providing excellent impact properties and high strength, also offer radiation resistance due to inherent high hydrogen content. SWCNT have exceptional mechanical and electrical properties. BNNT (figure 1) have high neutron cross section and good mechanical properties that add multi-functionality to this system. In this project, epoxy based UHMWPE composites containing SWCNT and BNNT are assessed for their use as bumper shields and as intermediate plates in a Whipple Shield for HVI resistance. Three composite systems are prepared to compare against one another: (I) Epoxy/UHMWPE, (II) Epoxy/UHMWPE/SWCNT and (III) Epoxy/UHMWPE/SWCNT/BNNT. Each composite is a 10.0 by 10.0 by 0.11 cm3 panel, consisting of 4 layers of fabrics arranged in cross-ply orientation. Both SWCNT and BNNT are 0.5 weight % of the fabric preform. Hypervelocity impact tests are performed using a two-stage light gas gun at Rice University

Method of Making Lightweight, Single Crystal Mirror

NASA Technical Reports Server (NTRS)

Bly, Vincent T. (Inventor)

2015-01-01

A method of making a mirror from a single crystal blank may include fine grinding top and bottom surfaces of the blank to be parallel. The blank may then be heat treated to near its melting temperature. An optical surface may be created on an optical side of the blank. A protector may be bonded to the optical surface. With the protector in place, the blank may be light weighted by grinding a non-optical surface of the blank using computer controlled grinding. The light weighting may include creating a structure having a substantially minimum mass necessary to maintain distortion of the mirror within a preset limit. A damaged layer of the non-optical surface caused by light weighting may be removed with an isotropic etch and/or repaired by heat treatment. If an oxide layer is present, the entire blank may then be etched using, for example, hydrofluoric acid. A reflecting coating may be deposited on the optical surface.

Size and weight graded multi-ply laminar electrodes

DOEpatents

Liu, Chia-Tsun; Demczyk, Brian G.; Rittko, Irvin R.

1984-01-01

An electrode is made comprising a porous backing sheet, and attached thereto a catalytically active layer having an electrolyte permeable side and a backing layer contacting side, where the active layer comprises a homogeneous mixture of active hydrophobic and hydrophilic agglomerates with catalyst disposed equally throughout the active layer, and where the agglomerate size increases from the electrolyte permeable side to the backing sheet contacting side.

Protective Effect of Total Flavones from Hippophae rhamnoides L. against Visible Light-Induced Retinal Degeneration in Pigmented Rabbits.

PubMed

Wang, Yong; Huang, Fenghong; Zhao, Liang; Zhang, Di; Wang, Ou; Guo, Xiaoxuan; Lu, Feng; Yang, Xue; Ji, Baoping; Deng, Qianchun

2016-01-13

Sea buckthorn (Hippophae rhamnoides L.) flavones have been used as candidate functional food ingredients because of their bioactivities, such as treating cardiovascular disorders, lowering plasma cholesterol level, and regulating immune function. However, the protective effects of sea buckthorn flavones against retinal degeneration remain unclear to date. This study investigated the protective effects of total flavones from H. rhamnoides (TFH) against visible light-induced retinal damage and explored the related mechanisms in pigmented rabbits. Rabbits were treated with TFH (250 and 500 mg/kg) for 2 weeks pre-illumination and 1 week post-illumination until sacrifice. Retinal function was quantified by performing electroretinography 1 day before and 1, 3, and 7 days after light exposure (18000 lx for 2 h). Retinal degeneration was evaluated by measuring the thickness of the outer nuclear layer (ONL) and performing the TUNEL assay 7 days after light exposure. Enzyme-linked immunosorbent assay, Western blot analysis, and immunohistochemistry were used to explore the antioxidant, anti-inflammatory, and anti-apoptotic mechanisms of TFH during visible light-induced retinal degeneration. Light exposure produced a degenerative effect primarily on the ONL, inner nuclear layer (INL), and ganglion cell layer (GCL). TFH significantly attenuated the destruction of electroretinograms caused by light damage, maintained ONL thickness, and decreased the number of TUNEL-positive cells in the INL and GCL. TFH ameliorated the retinal oxidative stress (GSH-Px, CAT, T-AOC, and MDA), inflammation (IL-1β and IL-6), angiogenesis (VEGF), and apoptosis (Bax, Bcl2, and caspase-3) induced by light exposure. Therefore, TFH exhibited protective effects against light-induced retinal degeneration by increasing the antioxidant defense mechanisms, suppressing pro-inflammatory and angiogenic cytokines, and inhibiting retinal cell apoptosis.

Energy transfer through a multi-layer liner for shaped charges

DOEpatents

Skolnick, Saul; Goodman, Albert

1985-01-01

This invention relates to the determination of parameters for selecting materials for use as liners in shaped charges to transfer the greatest amount of energy to the explosive jet. Multi-layer liners constructed of metal in shaped charges for oil well perforators or other applications are selected in accordance with the invention to maximize the penetrating effect of the explosive jet by reference to four parameters: (1) Adjusting the explosive charge to liner mass ratio to achieve a balance between the amount of explosive used in a shaped charge and the areal density of the liner material; (2) Adjusting the ductility of each layer of a multi-layer liner to enhance the formation of a longer energy jet; (3) Buffering the intermediate layers of a multi-layer liner by varying the properties of each layer, e.g., composition, thickness, ductility, acoustic impedance and areal density, to protect the final inside layer of high density material from shattering upon impact of the explosive force and, instead, flow smoothly into a jet; and (4) Adjusting the impedance of the layers in a liner to enhance the transmission and reduce the reflection of explosive energy across the interface between layers.

A four-panel enclosure protects from explosion

NASA Technical Reports Server (NTRS)

King, P. V.

1972-01-01

Development of multi-layered baffle as enclosure to protect personnel from effects of explosion during production of ammunition is discussed. Advantages of new system over previous systems are described. Illustration of typical panel structure is provided.

Ni Nanobuffer Layer Provides Light-Weight CNT/Cu Fibers with Superior Robustness, Conductivity, and Ampacity.

PubMed

Zou, Jingyun; Liu, Dandan; Zhao, Jingna; Hou, Ligan; Liu, Tong; Zhang, Xiaohua; Zhao, Yonghao; Zhu, Yuntian T; Li, Qingwen

2018-03-07

Carbon nanotube (CNT) fiber has not shown its advantage as next-generation light-weight conductor due to the large contact resistance between CNTs, as reflected by its low conductivity and ampacity. Coating CNT fiber with a metal layer like Cu has become an effective solution to this problem. However, the weak CNT-Cu interfacial bonding significantly limits the mechanical and electrical performances. Here, we report that a strong CNT-Cu interface can be formed by introducing a Ni nanobuffer layer before depositing the Cu layer. The Ni nanobuffer layer remarkably promotes the load and heat transfer efficiencies between the CNT fiber and Cu layer and improves the quality of the deposited Cu layer. As a result, the new composite fiber with a 2 μm thick Cu layer can exhibit a superhigh effective strength >800 MPa, electrical conductivity >2 × 10 7 S/m, and ampacity >1 × 10 5 A/cm 2 . The composite fiber can also sustain 10 000 times of bending and continuously work for 100 h at 90% ampacity.

Solution processed, white emitting tandem organic light-emitting diodes with inverted device architecture.

PubMed

Höfle, Stefan; Schienle, Alexander; Bernhard, Christoph; Bruns, Michael; Lemmer, Uli; Colsmann, Alexander

2014-08-13

Fully solution processed monochromatic and white-light emitting tandem or multi-photon polymer OLEDs with an inverted device architecture have been realized by employing WO3 /PEDOT:PSS/ZnO/PEI charge carrier generation layers. The luminance of the sub-OLEDs adds up in the stacked device indicating multi-photon emission. The white OLEDs exhibit a CRI of 75. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Insertion of two-dimensional photonic crystal pattern on p-GaN layer of GaN-based light-emitting diodes using bi-layer nanoimprint lithography.

PubMed

Byeon, Kyeong-Jae; Hwang, Seon-Yong; Hong, Chang-Hee; Baek, Jong Hyeob; Lee, Heon

2008-10-01

Nanoimprint lithography (NIL) was adapted to fabricate two-dimensional (2-D) photonic crystal (PC) pattern on the p-GaN layer of InGaN/GaN multi quantum well light-emitting diodes (LEDs) structure to improve the light extraction efficiency. For the uniform transfer of the PC pattern, a bi-layer imprinting method with liquid phase resin was used. The p-GaN layer was patterned with a periodic array of holes by an inductively coupled plasma etching process, based on SiCl4/Ar plasmas. As a result, 2-D photonic crystal patterns with 144 nm, 200 nm and 347 nm diameter holes were uniformly formed on the p-GaN layer and the photoluminescence (PL) intensity of each patterned LED samples was increased by more than 2.6 times, as compared to that of the un-patterned LED sample.

Nitride based quantum well light-emitting devices having improved current injection efficiency

DOEpatents

Tansu, Nelson; Zhao, Hongping; Liu, Guangyu; Arif, Ronald

2014-12-09

A III-nitride based device provides improved current injection efficiency by reducing thermionic carrier escape at high current density. The device includes a quantum well active layer and a pair of multi-layer barrier layers arranged symmetrically about the active layer. Each multi-layer barrier layer includes an inner layer abutting the active layer; and an outer layer abutting the inner layer. The inner barrier layer has a bandgap greater than that of the outer barrier layer. Both the inner and the outer barrier layer have bandgaps greater than that of the active layer. InGaN may be employed in the active layer, AlInN, AlInGaN or AlGaN may be employed in the inner barrier layer, and GaN may be employed in the outer barrier layer. Preferably, the inner layer is thin relative to the other layers. In one embodiment the inner barrier and active layers are 15 .ANG. and 24 .ANG. thick, respectively.

Flexible Shields for Protecting Spacecraft Against Debris

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Crews, Jeanne Lee

2004-01-01

A report presents the concept of Flexshield a class of versatile, lightweight, flexible shields for protecting spacecraft against impacts by small meteors and orbiting debris. The Flexshield concept incorporates elements of, but goes beyond, prior spacecraft-shielding concepts, including those of Whipple shields and, more recently, multi-shock shields and multi-shock blankets. A shield of the Flexshield type includes multiple outer layers (called bumpers in the art) made, variously, of advanced ceramic and/or polymeric fibers spaced apart from each other by a lightweight foam. As in prior such shields, the bumpers serve to shock an impinging hypervelocity particle, causing it to disintegrate vaporize, and spread out over a larger area so that it can be stopped by an innermost layer (back sheet). The flexibility of the fabric layers and compressibility of the foam make it possible to compress and fold the shield for transport, then deploy the shield for use. The shield can be attached to a spacecraft by use of snaps, hook-and-pile patches, or other devices. The shield can also contain multilayer insulation material, so that it provides some thermal protection in addition to mechanical protection.

Method of fabricating a 3-dimensional tool master

DOEpatents

Bonivert, William D.; Hachman, John T.

2002-01-01

The invention is a method for the fabrication of an imprint tool master. The process begins with a metallic substrate. A layer of photoresist is placed onto the metallic substrate and a image pattern mask is then aligned to the mask. The mask pattern has opaque portions that block exposure light and "open" or transparent portions which transmit exposure light. The photoresist layer is then exposed to light transmitted through the "open" portions of the first image pattern mask and the mask is then removed. A second layer of photoresist then can be placed onto the first photoresist layer and a second image pattern mask may be placed on the second layer of photoresist. The second layer of photoresist is exposed to light, as before, and the second mask removed. The photoresist layers are developed simultaneously to produce a multi-level master mandrel upon which a conductive film is formed. A tool master can now be formed onto the conductive film. An imprint tool is then produced from the tool master. In one embodiment, nickel is electroplated onto the tool master to produce a three-dimensional imprint tool.

Ceramic Electron Multiplier

DOE PAGES

Comby, G.

1996-10-01

The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

Broadband nonlinear optical response in multi-layer black phosphorus: an emerging infrared and mid-infrared optical material.

PubMed

Lu, S B; Miao, L L; Guo, Z N; Qi, X; Zhao, C J; Zhang, H; Wen, S C; Tang, D Y; Fan, D Y

2015-05-04

Black phosphorous (BP), the most thermodynamically stable allotrope of phosphorus, is a high-mobility layered semiconductor with direct band-gap determined by the number of layers from 0.3 eV (bulk) to 2.0 eV (single layer). Therefore, BP is considered as a natural candidate for broadband optical applications, particularly in the infrared (IR) and mid-IR part of the spectrum. The strong light-matter interaction, narrow direct band-gap, and wide range of tunable optical response make BP as a promising nonlinear optical material, particularly with great potentials for infrared and mid-infrared opto-electronics. Herein, we experimentally verified its broadband and enhanced saturable absorption of multi-layer BP (with a thickness of ~10 nm) by wide-band Z-scan measurement technique, and anticipated that multi-layer BPs could be developed as another new type of two-dimensional saturable absorber with operation bandwidth ranging from the visible (400 nm) towards mid-IR (at least 1930 nm). Our results might suggest that ultra-thin multi-layer BP films could be potentially developed as broadband ultra-fast photonics devices, such as passive Q-switcher, mode-locker, optical switcher etc.

Fully Solution-Processable Fabrication of Multi-Layered Circuits on a Flexible Substrate Using Laser Processing

PubMed Central

Ji, Seok Young; Choi, Wonsuk; Jeon, Jin-Woo; Chang, Won Seok

2018-01-01

The development of printing technologies has enabled the realization of electric circuit fabrication on a flexible substrate. However, the current technique remains restricted to single-layer patterning. In this paper, we demonstrate a fully solution-processable patterning approach for multi-layer circuits using a combined method of laser sintering and ablation. Selective laser sintering of silver (Ag) nanoparticle-based ink is applied to make conductive patterns on a heat-sensitive substrate and insulating layer. The laser beam path and irradiation fluence are controlled to create circuit patterns for flexible electronics. Microvia drilling using femtosecond laser through the polyvinylphenol-film insulating layer by laser ablation, as well as sequential coating of Ag ink and laser sintering, achieves an interlayer interconnection between multi-layer circuits. The dimension of microvia is determined by a sophisticated adjustment of the laser focal position and intensity. Based on these methods, a flexible electronic circuit with chip-size-package light-emitting diodes was successfully fabricated and demonstrated to have functional operations. PMID:29425144

Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

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

Aziz, Hammad, E-mail: engr.hammad.aziz03@gmail.com; Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Yusoff, P. S. M. Megat

Intumescent fire retardant coating (IFRC) is a passive fire protection system which swells upon heating to form expanded multi-cellular char layer that protects the substrate from fire. In this research work, IFRC’s were developed using different flame retardants such as ammonium polyphosphate, expandable graphite, melamine and boric acid. These flame retardants were bound together with the help of epoxy binder and cured together using curing agent. IFRC was then reinforced with nano magnesium oxide and nano alumina as inorganic fillers to study their effect towards fire performance, microstructure and thermal degradation. Small scale fire test was conducted to investigate themore » thermal insulation of coating whereas fire performance was calculated using thermal margin value. Field emission scanning electron microscopy was used to examine the microstructure of char obtained after fire test. Thermogravimetric analysis was conducted to investigate the residual weight of coating. Results showed that the performance of the coating was enhanced by reinforcement with nano size fillers as compared to non-filler based coating. Comparing both nano size magnesium oxide and nano size alumina; nano size alumina gave better fire performance with improved microstructure of char and high residual weight.« less

Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

NASA Astrophysics Data System (ADS)

Aziz, Hammad; Ahmad, Faiz; Yusoff, P. S. M. Megat; Zia-ul-Mustafa, M.

2015-07-01

Intumescent fire retardant coating (IFRC) is a passive fire protection system which swells upon heating to form expanded multi-cellular char layer that protects the substrate from fire. In this research work, IFRC's were developed using different flame retardants such as ammonium polyphosphate, expandable graphite, melamine and boric acid. These flame retardants were bound together with the help of epoxy binder and cured together using curing agent. IFRC was then reinforced with nano magnesium oxide and nano alumina as inorganic fillers to study their effect towards fire performance, microstructure and thermal degradation. Small scale fire test was conducted to investigate the thermal insulation of coating whereas fire performance was calculated using thermal margin value. Field emission scanning electron microscopy was used to examine the microstructure of char obtained after fire test. Thermogravimetric analysis was conducted to investigate the residual weight of coating. Results showed that the performance of the coating was enhanced by reinforcement with nano size fillers as compared to non-filler based coating. Comparing both nano size magnesium oxide and nano size alumina; nano size alumina gave better fire performance with improved microstructure of char and high residual weight.

Nanoparticle embedded p-type electrodes for GaN-based flip-chip light emitting diodes.

PubMed

Kwak, Joon Seop; Song, J O; Seong, T Y; Kim, B I; Cho, J; Sone, C; Park, Y

2006-11-01

We have investigated high-quality ohmic contacts for flip-chip light emitting diodes using Zn-Ni nanoparticles/Ag schemes. The Zn-Ni nanoparticles/Ag contacts produce specific contact resistances of 10(-5)-10(-6) omegacm2 when annealed at temperatures of 330-530 degrees C for 1 min in air ambient, which are much better than those obtained from the Ag contacts. It is shown that blue InGaN/GaN multi-quantum well light emitting diodes fabricated with the annealed Zn-Ni nanoparticles/Ag contacts give much lower forward-bias voltages at 20 mA compared with those of the multi-quantum well light emitting diodes made with the as-deposited Ag contacts. It is further presented that the multi-quantum well light emitting diodes made with the Zn-Ni nanoparticles/Ag contacts show similar output power compared to those fabricated with the Ag contact layers.

A preliminary study on puncture resistances of top and bottom layers of multi-layered needlepunched nonwoven geotextiles

NASA Astrophysics Data System (ADS)

Alan, G.; Tercan, M.

2017-10-01

Needlepunched nonwoven textiles are commonly used as geotextiles for various applications. Considering both environmental and economical benefits, utilization of recycled fibres in nonwoven geotextiles has become an attractive issue. Within this scope, the aim of this study is to evaluate the puncture resistance performances of top and bottom layers of multi-layered needle punched nonwovens made of recycled fibres to be used as membrane protective geotextiles by comparing them with those of made from polypropylene and polyester fibres. Puncture resistance results indicated that nonwovens made of recycled fibres demonstrated good performances at this preliminary stage.

Design and construction of a multi-layer CsI(Tl) telescope for high-energy reaction studies

NASA Astrophysics Data System (ADS)

Yan, D.; Sun, Z. Y.; Yue, K.; Wang, S. T.; Zhang, X. H.; Yu, Y. H.; Chen, J. L.; Tang, S. W.; Fang, F.; Zhou, Y.; Sun, Y.; Wang, Z. M.; Sun, Y. Z.

2017-01-01

A prototype of a new CsI(Tl) telescope, which will be used in the reaction studies of light isotopes with energy of several hundred AMeV, was constructed and tested at the Institute of Modern Physics, Chinese Academy of Sciences. The telescope has a multi-layer structure, and the range information was obtained to improve the particle identification performance. This prototype has seven layers of different thickness. An energy resolution of 5.0% (FWHM) was obtained for one of the layers in a beam test experiment. Positive improvement for the identification of 14O and 15O isotopes was achieved using the range information.

Al{sub 2}O{sub 3} multi-density layer structure as a moisture permeation barrier deposited by radio frequency remote plasma atomic layer deposition

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

Jung, Hyunsoo; Samsung Display Co. Ltd., Tangjeong, Chungcheongnam-Do 336-741; Jeon, Heeyoung

2014-02-21

Al{sub 2}O{sub 3} films deposited by remote plasma atomic layer deposition have been used for thin film encapsulation of organic light emitting diode. In this study, a multi-density layer structure consisting of two Al{sub 2}O{sub 3} layers with different densities are deposited with different deposition conditions of O{sub 2} plasma reactant time. This structure improves moisture permeation barrier characteristics, as confirmed by a water vapor transmission rate (WVTR) test. The lowest WVTR of the multi-density layer structure was 4.7 × 10{sup −5} gm{sup −2} day{sup −1}, which is one order of magnitude less than WVTR for the reference single-density Al{submore » 2}O{sub 3} layer. This improvement is attributed to the location mismatch of paths for atmospheric gases, such as O{sub 2} and H{sub 2}O, in the film due to different densities in the layers. This mechanism is analyzed by high resolution transmission electron microscopy, elastic recoil detection, and angle resolved X-ray photoelectron spectroscopy. These results confirmed that the multi-density layer structure exhibits very good characteristics as an encapsulation layer via location mismatch of paths for H{sub 2}O and O{sub 2} between the two layers.« less

Light scattering measurement of sodium polyacrylate products

NASA Astrophysics Data System (ADS)

Lama, Nisha; Norwood, David; Boone, Steven; Massie-Boyer, Valerie

2015-03-01

In the presentation, we will describe the use of a multi-detector HPLC incorporating the DAWN EOS multi-angle laser light scattering (MALLS) detector to measure the properties such as molecular weight, RMS radius, contour and persistence length and polydispersity of sodium polyacrylate products. The samples of sodium polyacrylate are used in various industries as thickening agents, coating dispersants, artificial snow, laundry detergent and disposable diapers. Data and results obtained from the experiment will be presented.

Multi-angle lensless digital holography for depth resolved imaging on a chip.

PubMed

Su, Ting-Wei; Isikman, Serhan O; Bishara, Waheb; Tseng, Derek; Erlinger, Anthony; Ozcan, Aydogan

2010-04-26

A multi-angle lensfree holographic imaging platform that can accurately characterize both the axial and lateral positions of cells located within multi-layered micro-channels is introduced. In this platform, lensfree digital holograms of the micro-objects on the chip are recorded at different illumination angles using partially coherent illumination. These digital holograms start to shift laterally on the sensor plane as the illumination angle of the source is tilted. Since the exact amount of this lateral shift of each object hologram can be calculated with an accuracy that beats the diffraction limit of light, the height of each cell from the substrate can be determined over a large field of view without the use of any lenses. We demonstrate the proof of concept of this multi-angle lensless imaging platform by using light emitting diodes to characterize various sized microparticles located on a chip with sub-micron axial and lateral localization over approximately 60 mm(2) field of view. Furthermore, we successfully apply this lensless imaging approach to simultaneously characterize blood samples located at multi-layered micro-channels in terms of the counts, individual thicknesses and the volumes of the cells at each layer. Because this platform does not require any lenses, lasers or other bulky optical/mechanical components, it provides a compact and high-throughput alternative to conventional approaches for cytometry and diagnostics applications involving lab on a chip systems.

The corrosion protection of AA2024-T3 aluminium alloy by leaching of lithium-containing salts from organic coatings.

PubMed

Visser, Peter; Liu, Yanwen; Zhou, Xiaorong; Hashimoto, Teruo; Thompson, George E; Lyon, Stuart B; van der Ven, Leendert G J; Mol, Arjan J M C; Terryn, Herman A

2015-01-01

Lithium carbonate and lithium oxalate were incorporated as leachable corrosion inhibitors in model organic coatings for the protection of AA2024-T3. The coated samples were artificially damaged with a scribe. It was found that the lithium-salts are able to leach from the organic coating and form a protective layer in the scribe on AA2024-T3 under neutral salt spray conditions. The present paper shows the first observation and analysis of these corrosion protective layers, generated from lithium-salt loaded organic coatings. The scribed areas were examined by scanning and transmission electron microscopy before and after neutral salt spray exposure (ASTM-B117). The protective layers typically consist of three different layered regions, including a relatively dense layer near the alloy substrate, a porous middle layer and a flake-shaped outer layer, with lithium uniformly distributed throughout all three layers. Scanning electron microscopy and white light interferometry surface roughness measurements demonstrate that the formation of the layer occurs rapidly and, therefore provides an effective inhibition mechanism. Based on the observation of this work, a mechanism is proposed for the formation of these protective layers.

Impact of rockfalls on protection measures: an experimental approach

NASA Astrophysics Data System (ADS)

Yuan, J.; Li, Y.; Huang, R.; Pei, X.

2015-01-01

The determination of rockfall impact force is crucial in designing the protection measures. In the present study, laboratory tests are carried out by taking the weight and shape of the falling rock fragments, drop height, incident angle, platform on the slideway and cushion layer on the protection measures as factors to investigate their influences on the impact force. The test results indicate that the impact force is positively exponential to the weight of rockfall and the instantaneous impact velocity of the rockfall approaching the protection measures. The impact velocity is found to be dominated not only by the drop height but also by the shape of rockfall as well as the length of the platform on the slideway. A great drop height and/or a short platform produce a fast impact velocity. Spherical rockfalls experience a reater impact velocity than cubic and cylindrical ones. A layer of cushion on the protection measures may reduce the impact force to a greater extent. The reduction effects are dominated by the cushion material and the thickness of the cushion layer. The thicker the cushion layer, the greater the reduction effect and the less the impact force. The stiffer the buffer material, the less the buffering effect and the greater the impact force. The present study indicates that the current standard in China for designing protection measures may overestimate the impact force by taking no consideration for the rockfall shape, platform and cushion layer.

Method for estimating optimal spectral and energy parameters of laser irradiation in photodynamic therapy of biological tissue

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

Lisenko, S A; Kugeiko, M M

We have solved the problem of layer-by-layer laser-light dosimetry in biological tissues and of selecting an individual therapeutic dose in laser therapy. A method is proposed for real-time monitoring of the radiation density in tissue layers in vivo, concentrations of its endogenous (natural) and exogenous (specially administered) chromophores, as well as in-depth distributions of the spectrum of light action on these chromophores. As the background information use is made of the spectrum of diffuse light reflected from a patient's tissue, measured by a fibre-optic spectrophotometer. The measured spectrum is quantitatively analysed by the method of approximating functions for fluxes ofmore » light multiply scattered in tissue and by a semi-analytical method for calculating the in-depth distribution of the light flux in a multi-layered medium. We have shown the possibility of employing the developed method for monitoring photosensitizer and oxyhaemoglobin concentrations in tissue, light power absorbed by chromophores in tissue layers at different depths and laser-induced changes in the tissue morphology (vascular volume content and ratios of various forms of haemoglobin) during photodynamic therapy. (biophotonics)« less

Multi-layer sparse representation for weighted LBP-patches based facial expression recognition.

PubMed

Jia, Qi; Gao, Xinkai; Guo, He; Luo, Zhongxuan; Wang, Yi

2015-03-19

In this paper, a novel facial expression recognition method based on sparse representation is proposed. Most contemporary facial expression recognition systems suffer from limited ability to handle image nuisances such as low resolution and noise. Especially for low intensity expression, most of the existing training methods have quite low recognition rates. Motivated by sparse representation, the problem can be solved by finding sparse coefficients of the test image by the whole training set. Deriving an effective facial representation from original face images is a vital step for successful facial expression recognition. We evaluate facial representation based on weighted local binary patterns, and Fisher separation criterion is used to calculate the weighs of patches. A multi-layer sparse representation framework is proposed for multi-intensity facial expression recognition, especially for low-intensity expressions and noisy expressions in reality, which is a critical problem but seldom addressed in the existing works. To this end, several experiments based on low-resolution and multi-intensity expressions are carried out. Promising results on publicly available databases demonstrate the potential of the proposed approach.

Multi-functional layered structure having structural and radiation shielding attributes

NASA Technical Reports Server (NTRS)

Kaul, Raj K. (Inventor); Barghouty, Abdulnasser Fakhri (Inventor); Penn, Benjamin G. (Inventor); Hulcher, Anthony Bruce (Inventor)

2010-01-01

A cosmic and solar radiation shielding structure that also has structural attributes is comprised of three layers. The first layer is 30-42 percent by volume of ultra-high molecular weight (UHMW) polyethylene fibers, 18-30 percent by volume of graphite fibers, and a remaining percent by volume of an epoxy resin matrix. The second layer is approximately 68 percent by volume of UHMW polyethylene fibers and a remaining percent by volume of a polyethylene matrix. The third layer is a ceramic material.

Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Composites

NASA Technical Reports Server (NTRS)

Kang, Jin Ho; Cano, Roberto J.; Ratcliffe, James G.; Luong, Hoa; Grimsley, Brian W.; Siochi, Emilie J.

2016-01-01

For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strengthand stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Despite several attempts to solve these issues with the addition of carbon nanotubes (CNT) into polymer matrices, and/or by interleaving CNT sheets between conventional carbon fiber (CF) composite layers, there are still interfacial problems that exist between CNTs (or CF) and the resin. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing (double cantilever beam and end-notched flexure test). Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated. Interleaving CNT sheets significantly improved the in-plane (axial and perpendicular direction of CF alignment) thermal conductivity of the hybrid composite laminates by 50 - 400%.

Grid-wide neuroimaging data federation in the context of the NeuroLOG project

PubMed Central

Michel, Franck; Gaignard, Alban; Ahmad, Farooq; Barillot, Christian; Batrancourt, Bénédicte; Dojat, Michel; Gibaud, Bernard; Girard, Pascal; Godard, David; Kassel, Gilles; Lingrand, Diane; Malandain, Grégoire; Montagnat, Johan; Pélégrini-Issac, Mélanie; Pennec, Xavier; Rojas Balderrama, Javier; Wali, Bacem

2010-01-01

Grid technologies are appealing to deal with the challenges raised by computational neurosciences and support multi-centric brain studies. However, core grids middleware hardly cope with the complex neuroimaging data representation and multi-layer data federation needs. Moreover, legacy neuroscience environments need to be preserved and cannot be simply superseded by grid services. This paper describes the NeuroLOG platform design and implementation, shedding light on its Data Management Layer. It addresses the integration of brain image files, associated relational metadata and neuroscience semantic data in a heterogeneous distributed environment, integrating legacy data managers through a mediation layer. PMID:20543431

Comparison of light-transmittance in dental tissues and dental composite restorations using incremental layering build-up with varying enamel resin layer thickness

PubMed Central

2018-01-01

Objectives To evaluate and compare light-transmittance in dental tissues and dental composite restorations using the incremental double-layer technique with varying layer thickness. Materials and Methods B1-colored natural teeth slabs were compared to dental restoration build-ups with A2D and B1E-colored nanofilled, supra-nanofilled, microfilled, and microhybrid composites. The enamel layer varied from 0.3, 0.5, or 1.2 mm thick, and the dentin layer was varied to provide a standardized 3.7 mm overall sample thickness (n = 10). All increments were light-cured to 16 J/cm2 with a multi-wave LED (Valo, Ultradent). Using a spectrophotometer, the samples were irradiated by an RGB laser beam. A voltmeter recorded the light output signal to calculate the light-transmittance through the specimens. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey's test (p = 0.05). Results Mean light-transmittance observed at thicker final layers of enamel were significantly lower than those observed at thinner final layers. Within 1.2 mm final enamel resin layer (FERL) thickness, all composites were similar to the dental tissues, with exception of the nanofilled composite. However, within 0.5 mm FERL thickness, only the supra-nanofilled composite showed no difference from the dental tissues. Within 0.3 mm FERL thickness, none of the composites were similar to the dental tissues. Conclusions The supra-nanofilled composite had the most similar light-transmittance pattern when compared to the natural teeth. However, for other composites, thicker FERL have a greater chance to match the light-transmittance of natural dental tissues. PMID:29765902

Comparison of light-transmittance in dental tissues and dental composite restorations using incremental layering build-up with varying enamel resin layer thickness.

PubMed

Rocha Maia, Rodrigo; Oliveira, Dayane; D'Antonio, Tracy; Qian, Fang; Skiff, Frederick

2018-05-01

To evaluate and compare light-transmittance in dental tissues and dental composite restorations using the incremental double-layer technique with varying layer thickness. B1-colored natural teeth slabs were compared to dental restoration build-ups with A2D and B1E-colored nanofilled, supra-nanofilled, microfilled, and microhybrid composites. The enamel layer varied from 0.3, 0.5, or 1.2 mm thick, and the dentin layer was varied to provide a standardized 3.7 mm overall sample thickness ( n = 10). All increments were light-cured to 16 J/cm 2 with a multi-wave LED (Valo, Ultradent). Using a spectrophotometer, the samples were irradiated by an RGB laser beam. A voltmeter recorded the light output signal to calculate the light-transmittance through the specimens. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey's test ( p = 0.05). Mean light-transmittance observed at thicker final layers of enamel were significantly lower than those observed at thinner final layers. Within 1.2 mm final enamel resin layer (FERL) thickness, all composites were similar to the dental tissues, with exception of the nanofilled composite. However, within 0.5 mm FERL thickness, only the supra-nanofilled composite showed no difference from the dental tissues. Within 0.3 mm FERL thickness, none of the composites were similar to the dental tissues. The supra-nanofilled composite had the most similar light-transmittance pattern when compared to the natural teeth. However, for other composites, thicker FERL have a greater chance to match the light-transmittance of natural dental tissues.

Distinguishing triplet energy transfer and trap-assisted recombination in multi-color organic light-emitting diode with an ultrathin phosphorescent emissive layer

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

Xue, Qin, E-mail: xueqin19851202@163.com; Liu, Shouyin; Xie, Guohua

2014-03-21

An ultrathin layer of deep-red phosphorescent emitter tris(1-phenylisoquinoline) iridium (III) (Ir(piq){sub 3}) is inserted within different positions of the electron blocking layer fac-tris (1-phenylpyrazolato-N,C{sup 2′})-iridium(III) (Ir(ppz){sub 3}) to distinguish the contribution of the emission from the triplet exciton energy transfer/diffusion from the adjacent blue phosphorescent emitter and the trap-assisted recombination from the narrow band-gap emitter itself. The charge trapping effect of the narrow band-gap deep-red emitter which forms a quantum-well-like structure also plays a role in shaping the electroluminescent characteristics of multi-color organic light-emitting diodes. By accurately controlling the position of the ultrathin sensing layer, it is considerably easy tomore » balance the white emission which is quite challenging for full-color devices with multiple emission zones. There is nearly no energy transfer detectable if 7 nm thick Ir(ppz){sub 3} is inserted between the blue phosphorescent emitter and the ultrathin red emitter.« less

Dense, layered membranes for hydrogen separation

DOEpatents

Roark, Shane E.; MacKay, Richard; Mundschau, Michael V.

2006-02-21

This invention provides hydrogen-permeable membranes for separation of hydrogen from hydrogen-containing gases. The membranes are multi-layer having a central hydrogen-permeable layer with one or more catalyst layers, barrier layers, and/or protective layers. The invention also relates to membrane reactors employing the hydrogen-permeable membranes of the invention and to methods for separation of hydrogen from a hydrogen-containing gas using the membranes and reactors. The reactors of this invention can be combined with additional reactor systems for direct use of the separated hydrogen.

White-light-controlled resistive switching in ZnO/BaTiO3/C multilayer layer at room temperature

NASA Astrophysics Data System (ADS)

Wang, Junshuai; Liang, Dandan; Wu, Liangchen; Li, Xiaoping; Chen, Peng

2018-07-01

The bipolar resistance switching effect is observed in ZnO/BaTiO3/C structure. The resistance switching behavior can be modulated by white light. The resistance switch states and threshold voltage can be changed when subjected to white light. This research can help explore multi-functional materials and applications in nonvolatile memory device.

Simulating Carbon cycle and phenology in complex forests using a multi-layer process based ecosystem model; evaluation and use of 3D-CMCC-Forest Ecosystem Model in a deciduous and an evergreen neighboring forests, within the area of Brasschaat (Be)

NASA Astrophysics Data System (ADS)

Marconi, S.; Collalti, A.; Santini, M.; Valentini, R.

2013-12-01

3D-CMCC-Forest Ecosystem Model is a process based model formerly developed for complex forest ecosystems to estimate growth, water and carbon cycles, phenology and competition processes on a daily/monthly time scale. The Model integrates some characteristics of the functional-structural tree models with the robustness of the light use efficiency approach. It treats different heights, ages and species as discrete classes, in competition for light (vertical structure) and space (horizontal structure). The present work evaluates the results of the recently developed daily version of 3D-CMCC-FEM for two neighboring different even aged and mono specific study cases. The former is a heterogeneous Pedunculate oak forest (Quercus robur L. ), the latter a more homogeneous Scot pine forest (Pinus sylvestris L.). The multi-layer approach has been evaluated against a series of simplified versions to determine whether the improved model complexity in canopy structure definition increases its predictive ability. Results show that a more complex structure (three height layers) should be preferable to simulate heterogeneous scenarios (Pedunculate oak stand), where heights distribution within the canopy justify the distinction in dominant, dominated and sub-dominated layers. On the contrary, it seems that using a multi-layer approach for more homogeneous stands (Scot pine stand) may be disadvantageous. Forcing the structure of an homogeneous stand to a multi-layer approach may in fact increase sources of uncertainty. On the other hand forcing complex forests to a mono layer simplified model, may cause an increase in mortality and a reduction in average DBH and Height. Compared with measured CO2 flux data, model results show good ability in estimating carbon sequestration trends, on both a monthly/seasonal and daily time scales. Moreover the model simulates quite well leaf phenology and the combined effects of the two different forest stands on CO2 fluxes.

Thermal-Structural Optimization of Integrated Cryogenic Propellant Tank Concepts for a Reusable Launch Vehicle

NASA Technical Reports Server (NTRS)

Johnson, Theodore F.; Waters, W. Allen; Singer, Thomas N.; Haftka, Raphael T.

2004-01-01

A next generation reusable launch vehicle (RLV) will require thermally efficient and light-weight cryogenic propellant tank structures. Since these tanks will be weight-critical, analytical tools must be developed to aid in sizing the thickness of insulation layers and structural geometry for optimal performance. Finite element method (FEM) models of the tank and insulation layers were created to analyze the thermal performance of the cryogenic insulation layer and thermal protection system (TPS) of the tanks. The thermal conditions of ground-hold and re-entry/soak-through for a typical RLV mission were used in the thermal sizing study. A general-purpose nonlinear FEM analysis code, capable of using temperature and pressure dependent material properties, was used as the thermal analysis code. Mechanical loads from ground handling and proof-pressure testing were used to size the structural geometry of an aluminum cryogenic tank wall. Nonlinear deterministic optimization and reliability optimization techniques were the analytical tools used to size the geometry of the isogrid stiffeners and thickness of the skin. The results from the sizing study indicate that a commercial FEM code can be used for thermal analyses to size the insulation thicknesses where the temperature and pressure were varied. The results from the structural sizing study show that using combined deterministic and reliability optimization techniques can obtain alternate and lighter designs than the designs obtained from deterministic optimization methods alone.

Asymmetrical flow field-flow fractionation with multi-angle light scattering and quasi-elastic light scattering for characterization of polymersomes: comparison with classical techniques.

PubMed

Till, Ugo; Gaucher-Delmas, Mireille; Saint-Aguet, Pascale; Hamon, Glenn; Marty, Jean-Daniel; Chassenieux, Christophe; Payré, Bruno; Goudounèche, Dominique; Mingotaud, Anne-Françoise; Violleau, Frédéric

2014-12-01

Polymersomes formed from amphiphilic block copolymers, such as poly(ethyleneoxide-b-ε-caprolactone) (PEO-b-PCL) or poly(ethyleneoxide-b-methylmethacrylate), were characterized by asymmetrical flow field-flow fractionation coupled with quasi-elastic light scattering (QELS), multi-angle light scattering (MALS), and refractive index detection, leading to the determination of their size, shape, and molecular weight. The method was cross-examined with more classical ones, like batch dynamic and static light scattering, electron microscopy, and atomic force microscopy. The results show good complementarities between all the techniques; asymmetrical flow field-flow fractionation being the most pertinent one when the sample exhibits several different types of population.

Burning Graphene Layer-by-Layer

PubMed Central

Ermakov, Victor A.; Alaferdov, Andrei V.; Vaz, Alfredo R.; Perim, Eric; Autreto, Pedro A. S.; Paupitz, Ricardo; Galvao, Douglas S.; Moshkalev, Stanislav A.

2015-01-01

Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in “cold-wall” reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material. PMID:26100466

Function of blue iridescence in tropical understorey plants

PubMed Central

Thomas, Katherine R.; Kolle, Mathias; Whitney, Heather M.; Glover, Beverley J.; Steiner, Ullrich

2010-01-01

The blue colouration seen in the leaves of Selaginella willdenowii is shown to be iridescent. Transmission electron microscopy studies confirm the presence of a layered lamellar structure of the upper cuticle of iridescent leaves. Modelling of these multi-layer structures suggests that they are responsible for the blue iridescence, confirming the link between the observed lamellae and the recorded optical properties. Comparison of blue and green leaves from the same plant indicates that the loss of the blue iridescence corresponds to a loss of the multi-layer structure. The results reported here do not support the idea that iridescence in plants acts to enhance light capture of photosynthetically important wavelengths. The reflectance of light in the range 600–700 nm is very similar for both iridescent and non-iridescent leaves. However, owing to the occurrence of blue colouration in a wide variety of shade dwelling plants it is probable that this iridescence has some adaptive benefit. Possible adaptive advantages of the blue iridescence in these plants are discussed. PMID:20519208

Variable Gap Conjugated Polymers

DTIC Science & Technology

2005-12-01

conducting gold interfacial layer interjected between the ITO glass electrode and the PEDOT/PSS hole transport layer . A family of low band gap, and near IR...which can be used as both electrochromics and as the hole transport layers in light emitting diodes. Hybrid electrochromic and electroluminescent (EC...MEH-PPV, P3HT, etc.) in order to blanket the solar spectrum. Initial device results on these multi-component blends are promising. In addition, we

Transitional analysis of organic thin color filter layers in displays during baking process using multi-speckle diffusing wave spectroscopy

NASA Astrophysics Data System (ADS)

Park, Baek Sung; Hyung, Kyung Hee; Oh, Gwi Jeong; Jung, Hyun Wook

2018-02-01

The color filter (CF) is one of the key components for improving the performance of TV displays such as liquid crystal display (LCD) and white organic light emitting diodes (WOLED). The profile defects like undercut during the fine fabrication processes for CF layers are inevitably generated through the UV exposure and development processes, however, these can be controlled through the baking process. In order to resolve the profile defects of CF layers, in this study, the real-time dynamic changes of CF layers are monitored during the baking process by changing components such as polymeric binder and acrylate. The motion of pigment particles in CF layers during baking is quantitatively interpreted using multi-speckle diffusing wave spectroscopy (MSDWS), in terms of the autocorrelation function and the characteristic time of α-relaxation.

Raman Monte Carlo simulation for light propagation for tissue with embedded objects

NASA Astrophysics Data System (ADS)

Periyasamy, Vijitha; Jaafar, Humaira Bte; Pramanik, Manojit

2018-02-01

Monte Carlo (MC) stimulation is one of the prominent simulation technique and is rapidly becoming the model of choice to study light-tissue interaction. Monte Carlo simulation for light transport in multi-layered tissue (MCML) is adapted and modelled with different geometry by integrating embedded objects of various shapes (i.e., sphere, cylinder, cuboid and ellipsoid) into the multi-layered structure. These geometries would be useful in providing a realistic tissue structure such as modelling for lymph nodes, tumors, blood vessels, head and other simulation medium. MC simulations were performed on various geometric medium. Simulation of MCML with embedded object (MCML-EO) was improvised for propagation of the photon in the defined medium with Raman scattering. The location of Raman photon generation is recorded. Simulations were experimented on a modelled breast tissue with tumor (spherical and ellipsoidal) and blood vessels (cylindrical). Results were presented in both A-line and B-line scans for embedded objects to determine spatial location where Raman photons were generated. Studies were done for different Raman probabilities.

Investigation of Electrical and Optical Properties of Highly Transparent TCO/Ag/TCO Multilayer.

PubMed

Kim, Sunbo; Lee, Jaehyeong; Dao, Vinh Ai; Ahn, Shihyun; Hussain, Shahzada Qamar; Park, Jinjoo; Jung, Junhee; Lee, Chan; Song, Bong-Shik; Choi, Byoungdeog; Lee, Youn-Jung; Iftiquar, S M; Yi, Junsin

2015-03-01

Transparent conductive oxides (TCOs) have been widely used as transparent electrodes for opto-electronic devices, such as solar cells, flat-panel displays, and light-emitting diodes, because of their unique characteristics of high optical transmittance and low electrical resistivity. Among various TCO materials, zinc oxide based films have recently received much attention because they have advantages over commonly used indium and tin-based oxide films. Most TCO films, however, exhibit valleys of transmittance in the wavelength range of 550-700 nm, lowering the average transmittance in the visible region and decreasing short-circuit current (Isc) of solar cells. A TCO/Ag/TCO multi-layer structure has emerged as an attractive alternative because it provides optical characteristics without the valley of transmittance compared with a 100-nm-thick single-layer TCO. In this article, we report the electrical, optical and surface properties of TCO/Ag/TCO. These multi-layers were deposited at room temperature with various Ag film thicknesses from 5 to 15 nm while the thickness of TCO thin film was fixed at 40 nm. The TCO/Ag/TCO multi-layer with a 10-nm-thick Ag film showed optimum transmittance in the visible (400-800 nm) wavelength region. These multi-layer structures have advantages over TCO layers of the same thickness.

Method for providing uranium with a protective copper coating

DOEpatents

Waldrop, Forrest B.; Jones, Edward

1981-01-01

The present invention is directed to a method for providing uranium metal with a protective coating of copper. Uranium metal is subjected to a conventional cleaning operation wherein oxides and other surface contaminants are removed, followed by etching and pickling operations. The copper coating is provided by first electrodepositing a thin and relatively porous flash layer of copper on the uranium in a copper cyanide bath. The resulting copper-layered article is then heated in an air or inert atmosphere to volatilize and drive off the volatile material underlying the copper flash layer. After the heating step an adherent and essentially non-porous layer of copper is electro-deposited on the flash layer of copper to provide an adherent, multi-layer copper coating which is essentially impervious to corrosion by most gases.

Penetration of UV-A, UV-B, blue, and red light into leaf tissues of pecan measured by a fiber optic microprobe system

NASA Astrophysics Data System (ADS)

Qi, Yadong; Bai, Shuju; Vogelmann, Thomas C.; Heisler, Gordon M.

2003-11-01

The depth of light penetration from the adaxial surfaces of the mature leaves of pecan (Carya illinoensis) was measured using a fiber optic microprobe system at four wavelengths: UV-B (310nm), UV-A (360 nm), blue light (430nm), and red light (680nm). The average thickness of the leaf adaxial epidermal layer was 15um and the total leaf thickness was 219um. The patterns of the light attenuation by the leaf tissues exhibited strong wavelength dependence. The leaf adaxial epidermal layer was chiefly responsible for absorbing the UV-A UV-B radiation. About 98% of 310 nm light was steeply attenuated within the first 5 um of the adaxial epidermis; thus, very little UV-B radiation was transmitted to the mesophyll tissues where contain photosynthetically sensitive sites. The adaxial epidermis also attenuated 96% of the UV-A radiation. In contrast, the blue and red light penetrated much deeper and was gradually attenutated by the leaves. The mesophyll tissues attenuated 17% of the blue light and 42% of the red light, which were available for photosynthesis use. Since the epidermal layer absorbed nearly all UV-B light, it acted as an effective filter screening out the harmful radiation and protecting photosynthetically sensitive tissues from the UV-B damage. Therefore, the epidermal function of the UV-B screening effectiveness can be regarded as one of the UV-B protection mechanisms in pecan.

Characterization of cinematographic films by Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Gaspard, S.; Oujja, M.; Rebollar, E.; Abrusci, C.; Catalina, F.; Castillejo, M.

2007-12-01

The emulsion-coated transparent plastic-base film has been the main carrier for production and preservation of motion picture contents since the 19th century. The knowledge of the composition of black and white silver gelatine cinematographic films is of great importance for the characterization of the photographic process and for identifying the optimum conditions for conservation. A cinematographic film is a multi-component system that consists of a layer of photographic emulsion overcoating a polymeric support (plasticized cellulose triacetate) and a protective transparent cross-linked gelatine layer coating the emulsion. In the present work, Laser Induced Breakdown Spectroscopy (LIBS) is used to characterize the composition of the materials of cinematographic films. LIB spectra of film samples and of different individual film components, polymeric support and reference gelatines, were acquired in vacuum by excitation at 266 nm (Q-switched Nd:YAG laser, 6 ns, 10 Hz). In the cinematographic film, silver lines from the light-sensitive silver halide salts of the photographic emulsion are accompanied by iron, lead, chrome and phosphorus lines. Iron and lead are constituents of film developers, chrome is included in the composition of the hardening agents and phosphorus has its origin in the plasticizer used in the polymeric support. By applying successive pulses on the same spot of the film sample, it was possible to observe through stratigraphic analysis the different layers composition. Additionally, the results obtained reveal the analytical capacity of LIBS for the study and classification of the different gelatine types and qualities used for the protecting layer and the photographic emulsion.

Hybrid algorithm for simulating the collimated transmittance of homogeneous stratified turbid media

PubMed Central

Cruzado, Beatriz Morales; Atencio, José Alberto Delgado; Vázquez y Montiel, Sergio; Gómez, Erick Sarmiento

2015-01-01

In this work we describe the development of a program that simulates the propagation of photons through refractive and reflecting optical components such as lenses, mirrors and stops that includes a biological tissue sample as the main issue to be investigated in order to get a simulated value of light distribution, in particular, of the unscattered light. The analysis of the photons that travel through the sample is based on the program Monte Carlo Multi-Layered with some modifications that consider a Gaussian beam as initial source of light. Position, directional cosines and weight of photons exiting the turbid media are used to propagate them through an optical system. As a mean of validation of the program, we selected a typical optical system for measurement of collimated transmittance. Therefore, several tests were carried out to find the optical system that gives the theoretical collimated transmittance at different values of the optical properties of the turbid media. Along this validation, the optimal experimental configuration is found. Using this results, a comparison between the simulated optimal configuration and the experimental set-up was done, by using a colloidal suspension as a turbid media. PMID:26137375

Theoretical design of multi-colored semi-transparent organic solar cells with both efficient color filtering and light harvesting

PubMed Central

Wen, Long; Chen, Qin; Sun, Fuhe; Song, Shichao; Jin, Lin; Yu, Yan

2014-01-01

Solar cells incorporated with multi-coloring capability not only offer an aesthetic solution to bridge the gap between solar modules and building decorations but also open up the possibility for self-powered colorful display. In this paper, we proposed a multi-colored semi-transparent organic solar cells (TOSCs) design containing metallic nanostructures with the both high color purity and efficiency based on theoretical considerations. By employing guided mode resonance effect, the multi-colored TOSC behave like an efficient color filter that selectively transmits light with the desired wavelengths and generates electricity with light of other wavelengths. Broad range of coloring and luminosity adjusting for the transmission light can be achieved by simply tuning the period and the duty cycle of the metallic nanostructures. Furthermore, accompanying with the efficient color filtering characteristics, the optical absorption of TOSCs was improved due to the marked suppression of transmission loss at the off-resonance wavelengths and the increased light trapping in TOSCs. The mechanisms of the light guiding in photoactive layer and broadband backward scattering from the metallic nanostructures were identified to make an essential contribution to the improved light-harvesting. By enabling efficient color control and high efficiency simultaneously, this approach holds great promise for future versatile photovoltaic energy utilization. PMID:25391756

Theoretical design of multi-colored semi-transparent organic solar cells with both efficient color filtering and light harvesting.

PubMed

Wen, Long; Chen, Qin; Sun, Fuhe; Song, Shichao; Jin, Lin; Yu, Yan

2014-11-13

Solar cells incorporated with multi-coloring capability not only offer an aesthetic solution to bridge the gap between solar modules and building decorations but also open up the possibility for self-powered colorful display. In this paper, we proposed a multi-colored semi-transparent organic solar cells (TOSCs) design containing metallic nanostructures with the both high color purity and efficiency based on theoretical considerations. By employing guided mode resonance effect, the multi-colored TOSC behave like an efficient color filter that selectively transmits light with the desired wavelengths and generates electricity with light of other wavelengths. Broad range of coloring and luminosity adjusting for the transmission light can be achieved by simply tuning the period and the duty cycle of the metallic nanostructures. Furthermore, accompanying with the efficient color filtering characteristics, the optical absorption of TOSCs was improved due to the marked suppression of transmission loss at the off-resonance wavelengths and the increased light trapping in TOSCs. The mechanisms of the light guiding in photoactive layer and broadband backward scattering from the metallic nanostructures were identified to make an essential contribution to the improved light-harvesting. By enabling efficient color control and high efficiency simultaneously, this approach holds great promise for future versatile photovoltaic energy utilization.

Regulation of alternative mRNA splicing: old players and new perspectives.

PubMed

Dvinge, Heidi

2018-06-01

Nearly all human multi-exon genes are subject to alternative splicing in one or more cell types. The splicing machinery, therefore, has to select between multiple splice sites in a context-dependent manner, relying on sequence features in cis and trans-acting splicing regulators that either promote or repress splice site recognition and spliceosome assembly. However, the functional coupling between multiple gene regulatory layers signifies that splicing can also be modulated by transcriptional or epigenetic characteristics. Other, less obvious, aspects of alternative splicing have come to light in recent years, often involving core components of the spliceosome previously thought to perform a basal rather than a regulatory role in splicing. Together this paints a highly dynamic picture of splicing regulation, where the final splice site choice is governed by the entire transcriptional environment of a gene and its cellular context. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

"Defense-in-Depth" Laser Safety and the National Ignition Facility

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

King, J J

The National Ignition Facility (NIF) is the largest and most energetic laser in the world contained in a complex the size of a football stadium. From the initial laser pulse, provided by telecommunication style infrared nanoJoule pulsed lasers, to the final 192 laser beams (1.8 Mega Joules total energy in the ultraviolet) converging on a target the size of a pencil eraser, laser safety is of paramount concern. In addition to this, there are numerous high-powered (Class 3B and 4) diagnostic lasers in use that can potentially send their laser radiation travelling throughout the facility. With individual beam paths ofmore » up to 1500 meters and a workforce of more than one thousand, the potential for exposure is significant. Simple laser safety practices utilized in typical laser labs just don't apply. To mitigate these hazards, NIF incorporates a multi layered approach to laser safety or 'Defense in Depth.' Most typical high-powered laser operations are contained and controlled within a single room using relatively simplistic controls to protect both the worker and the public. Laser workers are trained, use a standard operating procedure, and are required to wear Personal Protective Equipment (PPE) such as Laser Protective Eyewear (LPE) if the system is not fully enclosed. Non-workers are protected by means of posting the room with a warning sign and a flashing light. In the best of cases, a Safety Interlock System (SIS) will be employed which will 'safe' the laser in the case of unauthorized access. This type of laser operation is relatively easy to employ and manage. As the operation becomes more complex, higher levels of control are required to ensure personnel safety. Examples requiring enhanced controls are outdoor and multi-room laser operations. At the NIF there are 192 beam lines and numerous other Class 4 diagnostic lasers that can potentially deliver their hazardous energy to locations far from the laser source. This presents a serious and complex potential hazard to personnel. Because of this, a multilayered approach to safety is taken. This paper presents the philosophy and approach taken at the NIF in the multi-layered 'defense-in-depth' approach to laser safety.« less

Multi-layer holographic bifurcative neural network system for real-time adaptive EOS data analysis

NASA Technical Reports Server (NTRS)

Liu, Hua-Kuang; Huang, K. S.; Diep, J.

1993-01-01

Optical data processing techniques have the inherent advantage of high data throughout, low weight and low power requirements. These features are particularly desirable for onboard spacecraft in-situ real-time data analysis and data compression applications. the proposed multi-layer optical holographic neural net pattern recognition technique will utilize the nonlinear photorefractive devices for real-time adaptive learning to classify input data content and recognize unexpected features. Information can be stored either in analog or digital form in a nonlinear photofractive device. The recording can be accomplished in time scales ranging from milliseconds to microseconds. When a system consisting of these devices is organized in a multi-layer structure, a feedforward neural net with bifurcating data classification capability is formed. The interdisciplinary research will involve the collaboration with top digital computer architecture experts at the University of Southern California.

Application of fuzzy AHP method to IOCG prospectivity mapping: A case study in Taherabad prospecting area, eastern Iran

NASA Astrophysics Data System (ADS)

Najafi, Ali; Karimpour, Mohammad Hassan; Ghaderi, Majid

2014-12-01

Using fuzzy analytical hierarchy process (AHP) technique, we propose a method for mineral prospectivity mapping (MPM) which is commonly used for exploration of mineral deposits. The fuzzy AHP is a popular technique which has been applied for multi-criteria decision-making (MCDM) problems. In this paper we used fuzzy AHP and geospatial information system (GIS) to generate prospectivity model for Iron Oxide Copper-Gold (IOCG) mineralization on the basis of its conceptual model and geo-evidence layers derived from geological, geochemical, and geophysical data in Taherabad area, eastern Iran. The FuzzyAHP was used to determine the weights belonging to each criterion. Three geoscientists knowledge on exploration of IOCG-type mineralization have been applied to assign weights to evidence layers in fuzzy AHP MPM approach. After assigning normalized weights to all evidential layers, fuzzy operator was applied to integrate weighted evidence layers. Finally for evaluating the ability of the applied approach to delineate reliable target areas, locations of known mineral deposits in the study area were used. The results demonstrate the acceptable outcomes for IOCG exploration.

Real-time sensor validation and fusion for distributed autonomous sensors

NASA Astrophysics Data System (ADS)

Yuan, Xiaojing; Li, Xiangshang; Buckles, Bill P.

2004-04-01

Multi-sensor data fusion has found widespread applications in industrial and research sectors. The purpose of real time multi-sensor data fusion is to dynamically estimate an improved system model from a set of different data sources, i.e., sensors. This paper presented a systematic and unified real time sensor validation and fusion framework (RTSVFF) based on distributed autonomous sensors. The RTSVFF is an open architecture which consists of four layers - the transaction layer, the process fusion layer, the control layer, and the planning layer. This paradigm facilitates distribution of intelligence to the sensor level and sharing of information among sensors, controllers, and other devices in the system. The openness of the architecture also provides a platform to test different sensor validation and fusion algorithms and thus facilitates the selection of near optimal algorithms for specific sensor fusion application. In the version of the model presented in this paper, confidence weighted averaging is employed to address the dynamic system state issue noted above. The state is computed using an adaptive estimator and dynamic validation curve for numeric data fusion and a robust diagnostic map for decision level qualitative fusion. The framework is then applied to automatic monitoring of a gas-turbine engine, including a performance comparison of the proposed real-time sensor fusion algorithms and a traditional numerical weighted average.

Self-controlled children stay leaner in the transition to adolescence

PubMed Central

Duckworth, Angela L.; Tsukayama, Eli; Geier, Andrew B.

2010-01-01

In a prospective longitudinal study, we examined whether the personality trait of self-control protects against weight gain during the transition from childhood to adolescence. We obtained multi-method, multi-source measures of self-control from a socioeconomically and ethnically diverse sample of 105 fifth-grade students. Height and weight were recorded by the school nurse and used to calculate age- and gender-specific standardized body mass index (BMI) z-scores. Self-controlled fifth graders had lower BMI z-scores in eighth grade compared to their more impulsive peers, and this relationship remained significant when controlling for potential confounds, including gender, age, socioeconomic status, ethnicity, IQ, and happiness. Moreover, when controlling for the same covariates, self-control measured in fifth grade predicted decreases in BMI z-scores from fifth to eighth grade. These results suggest that more self-controlled children are protected from weight gain in the transition to adolescence. PMID:20004223

Application of multi-criteria decision analysis in prediction of groundwater resources potential: A case of Oke-Ana, Ilesa Area Southwestern, Nigeria

NASA Astrophysics Data System (ADS)

Akinlalu, A. A.; Adegbuyiro, A.; Adiat, K. A. N.; Akeredolu, B. E.; Lateef, W. Y.

2017-06-01

Groundwater Potential of Oke-Ana area southwestern Nigeria have been evaluated using the integration of electrical resistivity method, remote sensing and geographic information systems. The effect of five hydrogeological indices, namely lineament density, drainage density, lithology, overburden thickness and aquifer layer resistivity on groundwater occurrence was established. Multi-criteria decision analysis technique was employed to assign weight to each of the index using the concept of analytical hierarchy process. The assigned weight was normalized and consistency ratio was established. In order to evaluate the groundwater potential of Oke-Ana, sixty-seven (67) vertical electrical sounding points were occupied. Ten curve types were delineated in the study area. The curve types vary from simple three layer A and H-type curves to the more complex four, five and six layer AA, HA, KH, QH, AKH, HKH, KHA and KHKH curves. Four subsurface geo-electric sequences of top soil, weathered layer, partially weathered/fractured basement and the fresh basement were delineated in the area. The analytical process assisted in classifying Oke-Ana into, low, medium and high groundwater potential zones. Validation of the model from well information and two aborted boreholes suggest 70% agreement.

Evaluation of atomic layer deposited alumina as a protective layer for domestic silver articles: Anti-corrosion test in artificial sweat

NASA Astrophysics Data System (ADS)

Park, Suk Won; Han, Gwon Deok; Choi, Hyung Jong; Prinz, Fritz B.; Shim, Joon Hyung

2018-05-01

This study evaluated the effectiveness of alumina fabricated by atomic layer deposition (ALD) as a protective coating for silver articles against the corrosion caused by body contact. An artificial sweat solution was used to simulate body contact. ALD alumina layers of varying thicknesses ranging from 20 to 80 nm were deposited on sputtered silver samples. The stability of the protective layer was evaluated by immersing the coated samples in the artificial sweat solution at 25 and 35 °C for 24 h. We confirmed that a sufficiently thick layer of ALD alumina is effective in protecting the shape and light reflectance of the underlying silver, whereas the uncoated bare silver is severely degraded by the artificial sweat solution. Inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy were used for in-depth analyses of the chemical stability of the ALD-coated silver samples after immersion in the sweat solution.

Heat resistive dielectric multi-layer micro-mirror array in epitaxial lateral overgrowth gallium nitride.

PubMed

Huang, Chen-Yang; Ku, Hao-Min; Liao, Wei-Tsai; Chao, Chu-Li; Tsay, Jenq-Dar; Chao, Shiuh

2009-03-30

Ta2O5 / SiO2 dielectric multi-layer micro-mirror array (MMA) with 3mm mirror size and 6mm array period was fabricated on c-plane sapphire substrate. The MMA was subjected to 1200 degrees C high temperature annealing and remained intact with high reflectance in contrast to the continuous multi-layer for which the layers have undergone severe damage by 1200 degrees C annealing. Epitaxial lateral overgrowth (ELO) of gallium nitride (GaN) was applied to the MMA that was deposited on both sapphire and sapphire with 2:56 mm GaN template. The MMA was fully embedded in the ELO GaN and remained intact. The result implies that our MMA is compatible to the high temperature growth environment of GaN and the MMA could be incorporated into the structure of the micro-LED array as a one to one micro backlight reflector, or as the patterned structure on the large area LED for controlling the output light.

Depth profiling of galvanoaluminium-nickel coatings on steel by UV- and VIS-LIBS

NASA Astrophysics Data System (ADS)

Nagy, T. O.; Pacher, U.; Giesriegl, A.; Weimerskirch, M. J. J.; Kautek, W.

2017-10-01

Laser-induced depth profiling was applied to the investigation of galvanised steel sheets as a typical modern multi-layer coating system for environmental corrosion protection. The samples were ablated stepwise by the use of two different wavelengths of a frequency-converted Nd:YAG-laser, 266 nm and 532 nm, with a pulse duration of τ = 4 ns at fluences ranging from F = 50 to 250 J cm-2. The emission light of the resulting plasma was analysed as a function of both penetration depth and elemental spectrum in terms of linear correlation analysis. Elemental depth profiles were calculated and compared to EDX-cross sections of the cut sample. A proven mathematical algorithm designed for the reconstruction of layer structures from distorted emission traces caused by the Gaussian ablation profile can even resolve thin intermediate layers in terms of depth and thickness. The obtained results were compared to a purely thermally controlled ablation model. Thereby light-plasma coupling is suggested to be a possible cause of deviations in the ablation behaviour of Al. The average ablation rate h as a function of fluence F for Ni ranges from 1 to 3.5 μm/pulse for λ = 266 nm as well as for λ = 532 nm. In contrast, the range of h for Al differs from 2 to 4 μm/pulse for λ = 532 nm and 4 to 8 μm/pulse for λ = 266 nm in the exact same fluence range on the exact same sample.

Aircraft Icing Handbook. Volume 2

DTIC Science & Technology

1991-03-01

an airfoil surface. icenhobig - A surface property exhibiting a reduced adhesion to ice; literally, "ice-hating." light icing - The rate of...power, and are a light weight system of reasonable cost. K. ill I-I1 1.I.2 Pneumatic Impulse Ice Protection A Pneumatic Impulse Ice Protection System...should be about 5 to 6 seconds. During moderate icing a 60 second cycle is suggested, while for light icing, longer accretion times of 3 to 4 minutes

Method for producing nanowire-polymer composite electrodes

DOEpatents

Pei, Qibing; Yu, Zhibin

2017-11-21

A method for producing flexible, nanoparticle-polymer composite electrodes is described. Conductive nanoparticles, preferably metal nanowires or nanotubes, are deposited on a smooth surface of a platform to produce a porous conductive layer. A second application of conductive nanoparticles or a mixture of nanoparticles can also be deposited to form a porous conductive layer. The conductive layer is then coated with at least one coating of monomers that is polymerized to form a conductive layer-polymer composite film. Optionally, a protective coating can be applied to the top of the composite film. In one embodiment, the monomer coating includes light transducing particles to reduce the total internal reflection of light through the composite film or pigments that absorb light at one wavelength and re-emit light at a longer wavelength. The resulting composite film has an active side that is smooth with surface height variations of 100 nm or less.

Fabrication of Organic Thin Film Transistors Using Layer-By-Layer Assembly (Preprint)

DTIC Science & Technology

2007-03-01

thin-film transistors ( TFTs ) have received considerable attention as a low- cost, light-weight, flexible alternative to traditional amorphous silicon...Previous studies have investigated the use of a number of materials for both the active layer and the gate dielectric in various TFT architectures. These...performance. Conjugated small molecules, such as pentacene, or polymers, such as poly(3- hexylthiophene), are commonly used as the active layer in organic TFT

Spectrum splitting using multi-layer dielectric meta-surfaces for efficient solar energy harvesting

NASA Astrophysics Data System (ADS)

Yao, Yuhan; Liu, He; Wu, Wei

2014-06-01

We designed a high-efficiency dispersive mirror based on multi-layer dielectric meta-surfaces. By replacing the secondary mirror of a dome solar concentrator with this dispersive mirror, the solar concentrator can be converted into a spectrum-splitting photovoltaic system with higher energy harvesting efficiency and potentially lower cost. The meta-surfaces are consisted of high-index contrast gratings (HCG). The structures and parameters of the dispersive mirror (i.e. stacked HCG) are optimized based on finite-difference time-domain and rigorous coupled-wave analysis method. Our numerical study shows that the dispersive mirror can direct light with different wavelengths into different angles in the entire solar spectrum, maintaining very low energy loss. Our approach will not only improve the energy harvesting efficiency, but also lower the cost by using single junction cells instead of multi-layer tandem solar cells. Moreover, this approach has the minimal disruption to the existing solar concentrator infrastructures.

Enhanced light extraction efficiency of GaN-based light-emittng diodes by nitrogen implanted current blocking layer

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

Kim, Yong Deok; Oh, Seung Kyu; Park, Min Joo

Highlights: • A nitrogen implanted current-blocking layer was successfully demonstrated. • Light-extraction efficiency and radiant intensity was increased by more than 20%. • Ion implantation was successfully implemented in GaN based light-emitting diodes. - Abstract: GaN-based light emitting diodes (LEDs) with a nitrogen implanted current-blocking layer (CBL) were successfully demonstrated for improving the light extraction efficiency (LEE) and radiant intensity. The LEE and radiant intensity of the LEDs with a shallow implanted CBL with nitrogen was greatly increased by more than 20% compared to that of a conventional LED without the CBL due to an increase in the effective currentmore » path, which reduces light absorption at the thick p-pad electrode. Meanwhile, deep implanted CBL with a nitrogen resulted in deterioration of the LEE and radiant intensity because of formation of crystal damage, followed by absorption of the light generated at the multi-quantum well(MQW). These results clearly suggest that ion implantation method, which is widely applied in the fabrication of Si based devices, can be successfully implemented in the fabrication of GaN based LEDs by optimization of implanted depth.« less

Metallic corrosion processes reactivation sustained by iron-reducing bacteria: Implication on long-term stability of protective layers

NASA Astrophysics Data System (ADS)

Esnault, L.; Jullien, M.; Mustin, C.; Bildstein, O.; Libert, M.

In deep geological environments foreseen for the disposal of radioactive waste, metallic containers will undergo anaerobic corrosion. In this context, the formation of corrosion products such as magnetite may reduce the rate of corrosion processes through the formation of a protective layer. This study aims at determining the direct impact of iron-reducing bacteria (IRB) activity on the stability of corrosion protective layers. Batch experiments investigating iron corrosion processes including the formation of secondary magnetite and its subsequent alteration in the presence of IRB show the bacteria ability to use structural Fe(III) for respiration which leads to the sustainment of a high corrosion rate. With the bio-reduction of corrosion products such as magnetite, and H 2 as electron donor, IRB promote the reactivation of corrosion processes in corrosive environments by altering the protective layer. This phenomenon could have a major impact on the long-term stability of metallic compounds involved in multi-barrier system for high-level radioactive waste containment.

Effect of multi-dimensional ultraviolet light exposure on the growth of pentacene film and application to organic field-effect transistors.

PubMed

Bae, Jin-Hyuk; Lee, Sin-Doo; Choi, Jong Sun; Park, Jaehoon

2012-05-01

We report on the multi-dimensional alignment of pentacene molecules on a poly(methyl methacrylate)-based photosensitive polymer (PMMA-polymer) and its effect on the electrical performance of the pentacene-based field-effect transistor (FET). Pentacene molecules are shown to be preferentially aligned on the linearly polarized ultraviolet (LPUV)-exposed PMMA-polymer layer, which is contrast to an isotropic alignment on the bare PMMA-polymer layer. Multi-dimensional alignment of pentacene molecules in the film could be achieved by adjusting the direction of LPUV exposed to the PMMA-polymer. The control of pentacene molecular alignment is found to be promising for the field-effect mobility enhancement in the pentacene FET.

Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

NASA Astrophysics Data System (ADS)

Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

2018-01-01

Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

Progranulin, a Major Secreted Protein of Mouse Adipose-Derived Stem Cells, Inhibits Light-Induced Retinal Degeneration

PubMed Central

Tsuruma, Kazuhiro; Yamauchi, Mika; Sugitani, Sou; Otsuka, Tomohiro; Ohno, Yuta; Nagahara, Yuki; Ikegame, Yuka; Shimazawa, Masamitsu; Yoshimura, Shinichi; Iwama, Toru

2014-01-01

Adipose tissue stromal vascular fraction contains mesenchymal stem cells, which show protective effects when administered to damaged tissues, mainly through secreted trophic factors. We examined the protective effects of adipose-derived stem cells (ASCs) and ASC-conditioned medium (ASC-CM) against retinal damage and identified the neuroprotective factors in ASC-CM. ASCs and mature adipocytes were isolated from mouse subcutaneous tissue. ASCs were injected intravitreally in a mouse model of light-induced retinal damage, and ASC injection recovered retinal function as measured by electroretinogram and inhibited outer nuclear layer, thinning, without engraftment of ASCs. ASC-CM and mature adipocyte-conditioned medium were collected after 72 hours of culture. In vitro, H2O2- and light-induced cell death was reduced in a photoreceptor cell line with ASC-CM but not with mature adipocyte-conditioned medium. In vivo, light-induced photoreceptor damage was evaluated by measurement of outer nuclear layer thickness at 5 days after light exposure and by electroretinogram recording. ASC-CM significantly inhibited photoreceptor degeneration and retinal dysfunction after light exposure. Progranulin was identified as a major secreted protein of ASCs that showed protective effects against retinal damage in vitro and in vivo. Furthermore, progranulin phosphorylated extracellular signal-regulated kinase, cAMP response element binding protein, and hepatocyte growth factor receptor, and protein kinase C signaling pathways were involved in the protective effects of progranulin. These findings suggest that ASC-CM and progranulin have neuroprotective effects in the light-induced retinal-damage model. Progranulin may be a potential target for the treatment of the degenerative diseases of the retina. PMID:24233842

Progranulin, a major secreted protein of mouse adipose-derived stem cells, inhibits light-induced retinal degeneration.

PubMed

Tsuruma, Kazuhiro; Yamauchi, Mika; Sugitani, Sou; Otsuka, Tomohiro; Ohno, Yuta; Nagahara, Yuki; Ikegame, Yuka; Shimazawa, Masamitsu; Yoshimura, Shinichi; Iwama, Toru; Hara, Hideaki

2014-01-01

Adipose tissue stromal vascular fraction contains mesenchymal stem cells, which show protective effects when administered to damaged tissues, mainly through secreted trophic factors. We examined the protective effects of adipose-derived stem cells (ASCs) and ASC-conditioned medium (ASC-CM) against retinal damage and identified the neuroprotective factors in ASC-CM. ASCs and mature adipocytes were isolated from mouse subcutaneous tissue. ASCs were injected intravitreally in a mouse model of light-induced retinal damage, and ASC injection recovered retinal function as measured by electroretinogram and inhibited outer nuclear layer, thinning, without engraftment of ASCs. ASC-CM and mature adipocyte-conditioned medium were collected after 72 hours of culture. In vitro, H2O2- and light-induced cell death was reduced in a photoreceptor cell line with ASC-CM but not with mature adipocyte-conditioned medium. In vivo, light-induced photoreceptor damage was evaluated by measurement of outer nuclear layer thickness at 5 days after light exposure and by electroretinogram recording. ASC-CM significantly inhibited photoreceptor degeneration and retinal dysfunction after light exposure. Progranulin was identified as a major secreted protein of ASCs that showed protective effects against retinal damage in vitro and in vivo. Furthermore, progranulin phosphorylated extracellular signal-regulated kinase, cAMP response element binding protein, and hepatocyte growth factor receptor, and protein kinase C signaling pathways were involved in the protective effects of progranulin. These findings suggest that ASC-CM and progranulin have neuroprotective effects in the light-induced retinal-damage model. Progranulin may be a potential target for the treatment of the degenerative diseases of the retina.

A Complex Systems Approach to More Resilient Multi-Layered Security Systems

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

Brown, Nathanael J. K.; Jones, Katherine A.; Bandlow, Alisa

In July 2012, protestors cut through security fences and gained access to the Y-12 National Security Complex. This was believed to be a highly reliable, multi-layered security system. This report documents the results of a Laboratory Directed Research and Development (LDRD) project that created a consistent, robust mathematical framework using complex systems analysis algorithms and techniques to better understand the emergent behavior, vulnerabilities and resiliency of multi-layered security systems subject to budget constraints and competing security priorities. Because there are several dimensions to security system performance and a range of attacks that might occur, the framework is multi-objective for amore » performance frontier to be estimated. This research explicitly uses probability of intruder interruption given detection (P I) as the primary resilience metric. We demonstrate the utility of this framework with both notional as well as real-world examples of Physical Protection Systems (PPSs) and validate using a well-established force-on-force simulation tool, Umbra.« less

Thermal Performance Evaluation of Walls with Gas Filled Panel Insulation

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

Shrestha, Som S.; Desjarlais, Andre Omer; Atchley, Jerald Allen

Gas filled insulation panels (GFP) are very light weight and compact (when uninflated) advanced insulation products. GFPs consist of multiple layers of thin, low emittance (low-e) metalized aluminum. When expanded, the internal, low-e aluminum layers form a honeycomb structure. These baffled polymer chambers are enveloped by a sealed barrier and filled with either air or a low-conductivity gas. The sealed exterior aluminum foil barrier films provide thermal resistance, flammability protection, and properties to contain air or a low conductivity inert gas. This product was initially developed with a grant from the U.S. Department of Energy. The unexpanded product is nearlymore » flat for easy storage and transport. Therefore, transportation volume and weight of the GFP to fill unit volume of wall cavity is much smaller compared to that of other conventional insulation products. This feature makes this product appealing to use at Army Contingency Basing, when transportation cost is significant compared to the cost of materials. The objective of this study is to evaluate thermal performance of walls, similar to those used at typical Barracks Hut (B-Hut) hard shelters, when GFPs are used in the wall cavities. Oak Ridge National Laboratory (ORNL) tested performance of the wall in the rotatable guarded hotbox (RGHB) according to the ASTM C 1363 standard test method.« less

Mesoporous multi-shelled ZnO microspheres for the scattering layer of dye sensitized solar cell with a high efficiency

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

Xia, Weiwei; Mei, Chao; Zeng, Xianghua, E-mail: xhzeng@yzu.edu.cn

2016-03-14

Both light scattering and dye adsorbing are important for the power conversion efficiency PCE performance of dye sensitized solar cell (DSSC). Nanostructured scattering layers with a large specific surface area are regarded as an efficient way to improve the PCE by increasing dye adsorbing, but excess adsorbed dye will hinder light scattering and light penetration. Thus, how to balance the dye adsorbing and light penetration is a key problem to improve the PCE performance. Here, multiple-shelled ZnO microspheres with a mesoporous surface are fabricated by a hydrothermal method and are used as scattering layers on the TiO{sub 2} photoanode ofmore » the DSSC in the presence of N719 dye and iodine–based electrolyte, and the results reveal that the DSSCs based on triple shelled ZnO microsphere with a mesoporous surface exhibit an enhanced PCE of 7.66%, which is 13.0% higher than those without the scattering layers (6.78%), indicating that multiple-shelled microspheres with a mesoporous surface can ensure enough light scattering between the shells, and a favorable concentration of the adsorbed dye can improve the light penetration. These results may provide a promising pathway to obtain the high efficient DSSCs.« less

Ultra-Wideband Multi-Dye-Sensitized Upconverting Nanoparticles for Information Security Application.

PubMed

Lee, Jongha; Yoo, Byeongjun; Lee, Hakyong; Cha, Gi Doo; Lee, Hee-Su; Cho, Youngho; Kim, Sang Yeon; Seo, Hyunseon; Lee, Woongchan; Son, Donghee; Kang, Myungjoo; Kim, Hyung Min; Park, Yong Il; Hyeon, Taeghwan; Kim, Dae-Hyeong

2017-01-01

Multi-dye-sensitized upconverting nanoparticles (UCNPs), which harvest photons of wide wavelength range (450-975 nm) are designed and synthesized. The UCNPs embedded in a photo-acid generating layer are integrated on destructible nonvolatile resistive memory device. Upon illumination of light, the system permanently erases stored data, achieving enhanced information security. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atom Probe Tomography Analysis of Gallium-Nitride-Based Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Prosa, Ty J.; Olson, David; Giddings, A. Devin; Clifton, Peter H.; Larson, David J.; Lefebvre, Williams

2014-03-01

Thin-film light-emitting diodes (LEDs) composed of GaN/InxGa1-xN/GaN quantum well (QW) structures are integrated into modern optoelectronic devices because of the tunable InGaN band-gap enabling emission of the full visible spectrum. Atom probe tomography (APT) offers unique capabilities for 3D device characterization including compositional mapping of nano-volumes (>106 nm3) , high detection efficiency (>50%), and good sensitivity. In this study, APT is used to understand the distribution of dopants as well as Al and In alloying agents in a GaN device. Measurements using transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) have also been made to improve the accuracy of the APT analysis by correlating the information content of these complimentary techniques. APT analysis reveals various QW and other optoelectronic structures including a Mg p-GaN layer, an Al-rich electron blocking layer, an In-rich multi-QW region, and an In-based super-lattice structure. The multi-QW composition shows good quantitative agreement with layer thickness and spacing extracted from a high resolution TEM image intensity analysis.

Synergistic insecticidal and repellent effects of combined pyrethroid and repellent-impregnated bed nets using a novel long-lasting polymer-coating multi-layer technique.

PubMed

Faulde, Michael K; Nehring, Oliver

2012-08-01

New and improved strategies for malaria control and prevention are urgently needed. As a contribution to an optimized personal protection strategy, a novel long-lasting insecticide and repellent-treated net (LLIRN) has been designed by binding combinations of permethrin plus N,N-diethyl-m-toluamide (DEET), or insect repellent 3535 (IR3535), and etofenprox plus DEET, onto fibres of bed net fabric employing a new multi-layer polymer-coating technique. Protective repellent efficacy, toxicological effectiveness and residual activity of 12 LLIRN types have been evaluated by laboratory testing against adult Aedes aegypti. The novel multi-layer LLIRN design allowed simultaneous embedding at concentrations up to 5,930 mg/m(2) for DEET, 3,408 mg/m(2) for IR3535, 2,296 mg/m(2) for permethrin and 2,349 mg/m(2) for etofenprox, respectively. IR3535 layers prevented co-binding of additional pyrethroid-containing polymer layers, thus making pyrethroids plus DEET LLIRNs an ideal combination. All LLIRNs revealed synergistic insecticidal effects which, when measured against concentration controls of the isolated compounds, were significant in all LLIRN types designed. DEET in DEET plus permethrin LLIRNs significantly (p < 0.0001) reduced the concentration-dependent permethrin 100 % knockdown (KD) time from 55 to 75 %, the corresponding 100 % kill time (p < 0.0001) from 55 to 64 %. DEET in DEET plus etofenprox LLIRNs reduced the dose-specific 100 % knockdown (KD) time of etofenprox from 42 to 50 % (p = 0.004), the 100 % kill time from 25 to 38 % (p < 0.0001). Permethrin or etofenprox did not influence spatial repellency of DEET or IR3535 on LLIRNs. Vice versa, DEET and IR3535 increased spatial and excitatory repellency and reduced landing and probing frequency on LLIRNs resulting in strongly enhanced biting protection, even at low concentrations. One hundred percent biting and probing protection of stored LLIRNs was preserved for 83 weeks with the 5,930 mg/m(2) DEET and 2,139 mg/m(2) etofenprox LLIRN, for 72 weeks with the 5,002 mg/m(2) DEET and 2,349 mg/m(2) etofenprox LLIRN, for 63 weeks with the 3,590 mg/m(2) DEET and 1,208 mg/m(2) permethrin LLRN, and for 61 weeks with the 4,711 mg/m(2) DEET and 702 mg/m(2) etofenprox LLIRN. Because 100 % bite protection with up to 75 % quicker contact toxicity of pyrethroids were documented, synergistic toxicological and repellent effects of multi-layer polymer-coating LLIRNs may overcome LLIN-triggered selection pressure for development of new kdr- and metabolic pyrethroid resistances while simultaneously increasing protective efficacy also against kdr- and metabolic pyrethroid-resistant mosquitoes substantially due to the repellent-induced effects of LLIRNs thus indicating that this approach is a promising new candidate for future bed net, curtain, and window screen impregnation aiming at optimized prevention from mosquito-borne diseases.

Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes

PubMed Central

Lee, Jaeho; Han, Tae-Hee; Park, Min-Ho; Jung, Dae Yool; Seo, Jeongmin; Seo, Hong-Kyu; Cho, Hyunsu; Kim, Eunhye; Chung, Jin; Choi, Sung-Yool; Kim, Taek-Soo; Lee, Tae-Woo; Yoo, Seunghyup

2016-01-01

Graphene-based organic light-emitting diodes (OLEDs) have recently emerged as a key element essential in next-generation displays and lighting, mainly due to their promise for highly flexible light sources. However, their efficiency has been, at best, similar to that of conventional, indium tin oxide-based counterparts. We here propose an ideal electrode structure based on a synergetic interplay of high-index TiO2 layers and low-index hole-injection layers sandwiching graphene electrodes, which results in an ideal situation where enhancement by cavity resonance is maximized yet loss to surface plasmon polariton is mitigated. The proposed approach leads to OLEDs exhibiting ultrahigh external quantum efficiency of 40.8 and 62.1% (64.7 and 103% with a half-ball lens) for single- and multi-junction devices, respectively. The OLEDs made on plastics with those electrodes are repeatedly bendable at a radius of 2.3 mm, partly due to the TiO2 layers withstanding flexural strain up to 4% via crack-deflection toughening. PMID:27250743

Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes.

PubMed

Lee, Jaeho; Han, Tae-Hee; Park, Min-Ho; Jung, Dae Yool; Seo, Jeongmin; Seo, Hong-Kyu; Cho, Hyunsu; Kim, Eunhye; Chung, Jin; Choi, Sung-Yool; Kim, Taek-Soo; Lee, Tae-Woo; Yoo, Seunghyup

2016-06-02

Graphene-based organic light-emitting diodes (OLEDs) have recently emerged as a key element essential in next-generation displays and lighting, mainly due to their promise for highly flexible light sources. However, their efficiency has been, at best, similar to that of conventional, indium tin oxide-based counterparts. We here propose an ideal electrode structure based on a synergetic interplay of high-index TiO2 layers and low-index hole-injection layers sandwiching graphene electrodes, which results in an ideal situation where enhancement by cavity resonance is maximized yet loss to surface plasmon polariton is mitigated. The proposed approach leads to OLEDs exhibiting ultrahigh external quantum efficiency of 40.8 and 62.1% (64.7 and 103% with a half-ball lens) for single- and multi-junction devices, respectively. The OLEDs made on plastics with those electrodes are repeatedly bendable at a radius of 2.3 mm, partly due to the TiO2 layers withstanding flexural strain up to 4% via crack-deflection toughening.

Optimization of aircraft seat cushion fire blocking layers

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.; Ling, A. C.; Hovatter, W. R.

1983-01-01

This report describes work completed by the National Aeronautics and Space Administration - for the Federal Aviation Administration Technical Center. The purpose of this work was to examine the potential of fire blocking mechanisms for aircraft seat cushions in order to provide an optimized seat configuration with adequate fire protection and minimum weight. Aluminized thermally stable fabrics were found to provide adequate fire protection when used in conjunction with urethane foams, while maintaining minimum weight and cost penalty.

The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans

PubMed Central

Farci, Domenica; Slavov, Chavdar; Tramontano, Enzo; Piano, Dario

2016-01-01

Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under desiccation, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defense against UV radiation. PMID:26909071

The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans.

PubMed

Farci, Domenica; Slavov, Chavdar; Tramontano, Enzo; Piano, Dario

2016-01-01

Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under desiccation, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defense against UV radiation.

Thermal imaging for assessment of electron-beam freeform fabrication (EBF3) additive manufacturing deposits

NASA Astrophysics Data System (ADS)

Zalameda, Joseph N.; Burke, Eric R.; Hafley, Robert A.; Taminger, Karen M.; Domack, Christopher S.; Brewer, Amy; Martin, Richard E.

2013-05-01

Additive manufacturing is a rapidly growing field where 3-dimensional parts can be produced layer by layer. NASA's electron beam freeform fabrication (EBF3) technology is being evaluated to manufacture metallic parts in a space environment. The benefits of EBF3 technology are weight savings to support space missions, rapid prototyping in a zero gravity environment, and improved vehicle readiness. The EBF3 system is composed of 3 main components: electron beam gun, multi-axis position system, and metallic wire feeder. The electron beam is used to melt the wire and the multi-axis positioning system is used to build the part layer by layer. To insure a quality deposit, a near infrared (NIR) camera is used to image the melt pool and solidification areas. This paper describes the calibration and application of a NIR camera for temperature measurement. In addition, image processing techniques are presented for deposit assessment metrics.

Quantitative, depth-resolved determination of particle motion using multi-exposure, spatial frequency domain laser speckle imaging.

PubMed

Rice, Tyler B; Kwan, Elliott; Hayakawa, Carole K; Durkin, Anthony J; Choi, Bernard; Tromberg, Bruce J

2013-01-01

Laser Speckle Imaging (LSI) is a simple, noninvasive technique for rapid imaging of particle motion in scattering media such as biological tissue. LSI is generally used to derive a qualitative index of relative blood flow due to unknown impact from several variables that affect speckle contrast. These variables may include optical absorption and scattering coefficients, multi-layer dynamics including static, non-ergodic regions, and systematic effects such as laser coherence length. In order to account for these effects and move toward quantitative, depth-resolved LSI, we have developed a method that combines Monte Carlo modeling, multi-exposure speckle imaging (MESI), spatial frequency domain imaging (SFDI), and careful instrument calibration. Monte Carlo models were used to generate total and layer-specific fractional momentum transfer distributions. This information was used to predict speckle contrast as a function of exposure time, spatial frequency, layer thickness, and layer dynamics. To verify with experimental data, controlled phantom experiments with characteristic tissue optical properties were performed using a structured light speckle imaging system. Three main geometries were explored: 1) diffusive dynamic layer beneath a static layer, 2) static layer beneath a diffuse dynamic layer, and 3) directed flow (tube) submerged in a dynamic scattering layer. Data fits were performed using the Monte Carlo model, which accurately reconstructed the type of particle flow (diffusive or directed) in each layer, the layer thickness, and absolute flow speeds to within 15% or better.

Decrypting Information Sensitivity: Risk, Privacy, and Data Protection Law in the United States and the European Union

ERIC Educational Resources Information Center

Fazlioglu, Muge

2017-01-01

This dissertation examines the risk-based approach to privacy and data protection and the role of information sensitivity within risk management. Determining what information carries the greatest risk is a multi-layered challenge that involves balancing the rights and interests of multiple actors, including data controllers, data processors, and…

Biotronics

DTIC Science & Technology

2012-11-01

BLOCKING LAYER IN ORGANIC LIGHT EMITTING DIODES ............................70 2.3.1 Materials Used for the Fabrication of BioLEDs...optical losses. Using a lower molecular weight DNA-based biopolymer as the top and bottom cladding layers in an NLO polymer EO modulator, we were able...application, these new biopolymer -based materials have been used for many types of electronic and photonic applications. Even with growing research

Curiosity Heat Shield in Detail

NASA Image and Video Library

2012-08-08

This color full-resolution image showing the heat shield of NASA Curiosity rover was obtained during descent to the surface of Mars. This image shows the inside surface of the heat shield, with its protective multi-layered insulation.

40th Annual Armament Systems: Guns-Ammunition-Rockets-Missiles Conference and Exhibition

DTIC Science & Technology

2005-04-28

Session: Medium Caliber System Oerlikon Ammunition for New Defense Environment, Mr. Allan N. Buckley, BTECH Oerlikon Contraves Pyrotec AG Multi...Environment Mr. Allan N. Buckley, BTECH Oerlikon Contraves Pyrotec AG Force Protection - Multi Mission Vehicle Armament & Air Burst Munition for...determine homogeneity – Propellant contains ~3% by weight of FS grains to adjust K

Nanoparticulate hollow TiO2 fibers as light scatterers in dye-sensitized solar cells: layer-by-layer self-assembly parameters and mechanism.

PubMed

Rahman, Masoud; Tajabadi, Fariba; Shooshtari, Leyla; Taghavinia, Nima

2011-04-04

Hollow structures show both light scattering and light trapping, which makes them promising for dye-sensitized solar cell (DSSC) applications. In this work, nanoparticulate hollow TiO(2) fibers are prepared by layer-by-layer (LbL) self-assembly deposition of TiO(2) nanoparticles on natural cellulose fibers as template, followed by thermal removal of the template. The effect of LbL parameters such as the type and molecular weight of polyelectrolyte, number of dip cycles, and the TiO(2) dispersion (amorphous or crystalline sol) are investigated. LbL deposition with weak polyelectrolytes (polyethylenimine, PEI) gives greater nanoparticle deposition yield compared to strong polyelectrolytes (poly(diallyldimethylammonium chloride), PDDA). Decreasing the molecular weight of the polyelectrolyte results in more deposition of nanoparticles in each dip cycle with narrower pore size distribution. Fibers prepared by the deposition of crystalline TiO(2) nanoparticles show higher surface area and higher pore volume than amorphous nanoparticles. Scattering coefficients and backscattering properties of fibers are investigated and compared with those of commercial P25 nanoparticles. Composite P25-fiber films are electrophoretically deposited and employed as the photoanode in DSSC. Photoelectrochemical measurements showed an increase of around 50% in conversion efficiency. By employing the intensity-modulated photovoltage and photocurrent spectroscopy methods, it is shown that the performance improvement due to addition of fibers is mostly due to the increase in light-harvesting efficiency. The high surface area due to the nanoparticulate structure and strong light harvesting due to the hollow structure make these fibers promising scatterers in DSSCs. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphological, biochemical, histological, and ultrastructural protective effects of misoprostol on cisplatin induced-hepatotoxicity in adult male rats.

PubMed

Nasr, Ashraf Y

2013-12-01

To investigate the possible protective effect of misoprostol on cisplatin-induced hepatotoxicity. Four-equal sized groups (control, cisplatin-treated, misoprostol-treated, combined misoprostol, and cisplatin-treated) adult male Wistar rats (6 each) were used in this study. Body weight, liver weight, and liver weight/body weight ratio was calculated. Blood samples were obtained from the hearts of rats to determine the levels of total serum bilirubin (TSB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and albumin. Liver specimens were prepared for both light and electron microscopes. The study was carried out between June 2012 and April 2013 at the Anatomy Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt, and the Department of Anatomy, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia. A single cisplatin dose (7.5 mg/kg intraperitoneally) resulted in significant elevation of AST, ALT, and TSB serum levels, and a significant reduction of serum albumin level, body weight, liver weight, and liver weight/body weight ratio. A combination of misoprostol (200 ug/kg/day) with cisplatin improved most of the previous parameters. Examination of specimens by both light and electron microscopes revealed pericentral hepatic necrosis, periportal fibrosis, dilatation, and congestion of central vein and blood sinusoids, diminished glycogen content, degenerated mitochondria, vesicular dilated rough endoplasmic reticulum, and nuclear changes in cisplatin-treated rats. Oral intake of misoprostol with cisplatin improved many of these changes. The results indicate that misoprostol may have a protective effect on cisplatin-induced hepatotoxicity.

Detection of defects in multi-layered aramid composites by ultrasonic IR thermography

NASA Astrophysics Data System (ADS)

Pracht, Monika; Swiderski, Waldemar

2017-10-01

In military applications, laminates reinforced with aramid, carbon, and glass fibers are used for the construction of protection products against light ballistics. Material layers can be very different by their physical properties. Therefore, such materials represent a difficult inspection task for many traditional techniques of non-destructive testing (NDT). Defects which can appear in this type of many-layered composite materials usually are inaccuracies in gluing composite layers and stratifications or delaminations occurring under hits of fragments and bullets. IR thermographic NDT is considered as a candidate technique to detect such defects. One of the active IR thermography methods used in nondestructive testing is vibrothermography. The term vibrothermography was created in the 1990s to determine the thermal test procedures designed to assess the hidden heterogeneity of structural materials based on surface temperature fields at cyclical mechanical loads. A similar procedure can be done with sound and ultrasonic stimulation of the material, because the cause of an increase in temperature is internal friction between the wall defect and the stimulation mechanical waves. If the cyclic loading does not exceed the flexibility of the material and the rate of change is not large, the heat loss due to thermal conductivity is small, and the test object returns to its original shape and temperature. The most commonly used method is ultrasonic stimulation, and the testing technique is ultrasonic infrared thermography. Ultrasonic IR thermography is based on two basic phenomena. First, the elastic properties of defects differ from the surroundings, and acoustic damping and heating are always larger in the damaged regions than in the undamaged or homogeneous areas. Second, the heat transfer in the sample is dependent on its thermal properties. In this paper, both modelling and experimental results which illustrate the advantages and limitations of ultrasonic IR thermography in inspecting multi-layered aramide composite materials will be presented.

Multi-layer composite structure covered polytetrafluoroethylene for visible-infrared-radar spectral Compatibility

NASA Astrophysics Data System (ADS)

Qi, Dong; Cheng, Yongzhi; Wang, Xian; Wang, Fang; Li, Bowen; Gong, Rongzhou

2017-12-01

In this paper, a polytetrafluoroethylene (PTFE) top-covered multi-layer composite structure PTFE/H s/(Ge/ZnS)3 (H s represents the surface layer ZnS with various thicknesses) for spectral compatibility is proposed and investigated theoretically and experimentally. A substantial decline of glossiness from over 200 Gs to 74.2 Gs could be realized, due to high roughness and interface reflection of the 800 nm PTFE protection layer. In addition, similar to the structure of H s/(Ge/ZnS)3, the designed structure with a certain color exhibits ultra-low emissivity of average 0.196 at 8-14 µm and highly transparent performance of 96.45% in the radar frequency range of 2-18 GHz. Our design will provide an important reference for the practical applications of the spectral compatible multilayer films.

A dynamic ecosystem growth model for forests at high complexity structure

NASA Astrophysics Data System (ADS)

Collalti, A.; Perugini, L.; Chiti, T.; Matteucci, G.; Oriani, A.; Santini, M.; Papale, D.; Valentini, R.

2012-04-01

Forests ecosystem play an important role in carbon cycle, biodiversity conservation and for other ecosystem services and changes in their structure and status perturb a delicate equilibrium that involves not only vegetation components but also biogeochemical cycles and global climate. The approaches to determine the magnitude of these effects are nowadays various and one of those include the use of models able to simulate structural changes and the variations in forests yield The present work shows the development of a forest dynamic model, on ecosystem spatial scale using the well known light use efficiency to determine Gross Primary Production. The model is predictive and permits to simulate processes that determine forest growth, its dynamic and the effects of forest management using eco-physiological parameters easy to be assessed and to be measured. The model has been designed to consider a tri-dimensional cell structure composed by different vertical layers depending on the forest type that has to be simulated. These features enable the model to work on multi-layer and multi-species forest types, typical of Mediterranean environment, at the resolution of one hectare and at monthly time-step. The model simulates, for each layer, a value of available Photosynthetic Active Radiation (PAR) through Leaf Area Index, Light Extinction Coefficient and cell coverage, the transpiration rate that is closely linked to the intercepted light and the evaporation from soil. Using this model it is possible to evaluate the possible impacts of climate change on forests that may result in decrease or increase of productivity as well as the feedback of one or more dominated layers in terms of CO2 uptake in a forest stand and the effects of forest management activities during the forest harvesting cycle. The model has been parameterised, validated and applied in a multi-layer, multi-age and multi-species Italian turkey oak forest (Q. cerris L., C. betulus L. and C. avellana L.) where the medium-term (10 years) development of forest parameters were simulated. The results obtained for net primary production and for stem, root and foliage compartments as well as for forest structure i.e. Diameter at Breast Height, height and canopy cover are in good accordance with field data (R2>0.95). These results show how the model is able to predict forest yield as well as forest dynamic with good accuracy and encourage testing the model capability on other sites with a more complex forest structure and for long-time period with an higher spatial resolution.

[White organic light emitting device with dyestuff DCJTB blended in polymer].

PubMed

Zhang, Yan-Fei; Xu, Zheng; Zhang, Fu-Jun; Wang, Yong; Zhao, Su-Ling

2008-04-01

The Alq3 and DCJTB were blended with poly (N-vinylcarbazole) (PVK) in different weight ratios and spin coated into films. Multilayer devices with the light emitting layer PVK : Alq3 : DCJTB were fabricated, and their structure was ITO/ PVK : Alq3 : DCJTB/ BCP/Alq3/LiF/Al in which BCP and Alq3 were employed as the hole-blocking and electron-transporting layers respectively, PVK is the blue light-emitting as well as hole-transporting layer. The mass proportion of PVK relative to Alq3 was tuned while the quality ratio of PVK to DCJTB remained (100 : 1). Finally, fairly pure and stabile white emission was achieved when PVK : Alq3 : DCJTB was 100 : 5 : 1. The CIE coordinate was (0.33, 0.36) at 14 V, which is very stable at various biases (10-14 V).

Application of the diagnostic radiological index of protection to protective garments

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

Pasciak, Alexander S.; Jones, A. Kyle, E-mail: kyle.jones@mdanderson.org; Wagner, Louis K.

2015-02-15

Purpose: Previously, the diagnostic radiological index of protection (DRIP) was proposed as a metric for quantifying the protective value of radioprotective garments. The DRIP is a weighted sum of the percent transmissions of different radiation beams through a garment. Ideally, the beams would represent the anticipated stray radiation encountered during clinical use. However, it is impractical to expect a medical physicist to possess the equipment necessary to accurately measure transmission of scattered radiation. Therefore, as a proof of concept, the authors tested a method that applied the DRIP to clinical practice. Methods: Primary beam qualities used in interventional cardiology andmore » radiology were observed and catalogued. Based on the observed range of beam qualities, five representative clinical primary beam qualities, specified by kV and added filtration, were selected for this evaluation. Monte Carlo simulations were performed using these primary beams as source definitions to generate scattered spectra from the clinical primary beams. Using numerical optimization, ideal scatter mimicking primary beams, specified by kV and added aluminum filtration, were matched to the scattered spectra according to half- and quarter-value layers and spectral shape. To within reasonable approximation, these theoretical scatter-mimicking primary beams were reproduced experimentally in laboratory x ray beams and used to measure transmission through pure lead and protective garments. For this proof of concept, the DRIP for pure lead and the garments was calculated by assigning equal weighting to percent transmission measurements for each of the five beams. Finally, the areal density of lead and garments was measured for consideration alongside the DRIP to assess the protective value of each material for a given weight. Results: The authors identified ideal scatter mimicking primary beams that matched scattered spectra to within 0.01 mm for half- and quarter-value layers in copper and within 5% for the shape function. The corresponding experimental scatter-mimicking primary beams matched the Monte Carlo generated scattered spectra with maximum deviations of 6.8% and 6.6% for half- and quarter-value layers. The measured DRIP for 0.50 mm lead sheet was 2.0, indicating that it transmitted, on average, 2% of incident radiation. The measured DRIP for a lead garment and one lead-alternative garment closely matched that for pure lead of 0.50 mm thickness. The DRIP for other garments was substantially higher than 0.50 mm lead (3.9–5.4), indicating they transmitted about twice as much radiation. When the DRIP was plotted versus areal density, it was clear that, of the garments tested, none were better than lead on a weight-by-weight basis. Conclusions: A method for measuring the DRIP for protective garments using scatter-mimicking primary beams was developed. There was little discernable advantage in protective value per unit weight for lead-alternative versus lead-only garments. Careful consideration must be given to the balance of protection and weight when choosing a lead-alternative protective garment with a lower specified “lead equivalence,” e.g., 0.35 mm. The DRIP has the potential to resolve this dilemma. Reporting the DRIP relative to areal density is an ideal metric for objective comparisons of protective garment performance, considering both protective value in terms of transmission of radiation and garment weight.« less

Response of Antarctic cryoconite microbial communities to light.

PubMed

Bagshaw, Elizabeth A; Wadham, Jemma L; Tranter, Martyn; Perkins, Rupert; Morgan, Alistair; Williamson, Christopher J; Fountain, Andrew G; Fitzsimons, Sean; Dubnick, Ashley

2016-06-01

Microbial communities on polar glacier surfaces are found dispersed on the ice surface, or concentrated in cryoconite holes and cryolakes, which are accumulations of debris covered by a layer of ice for some or all of the year. The ice lid limits the penetration of photosynthetically available radiation (PAR) to the sediment layer, since the ice attenuates up to 99% of incoming radiation. This suite of field and laboratory experiments demonstrates that PAR is an important control on primary production in cryoconite and cryolake ecosystems. Increased light intensity increased efficiency of primary production in controlled laboratory incubations of debris from the surface of Joyce Glacier, McMurdo Dry Valleys, Antarctica. However, when light intensity was increased to levels near that received on the ice surface, without the protection of an ice lid, efficiency decreased and measurements of photophysiology showed that the communities suffered light stress. The communities are therefore well adapted to low light levels. Comparison with Arctic cryoconite communities, which are typically not covered by an ice lid for the majority of the ablation season, showed that these organisms were also stressed by high light, so they must employ strategies to protect against photodamage. © FEMS 2016.

Response of Antarctic cryoconite microbial communities to light

PubMed Central

Bagshaw, Elizabeth A.; Wadham, Jemma L.; Tranter, Martyn; Perkins, Rupert; Morgan, Alistair; Williamson, Christopher J.; Fountain, Andrew G.; Fitzsimons, Sean; Dubnick, Ashley

2016-01-01

Microbial communities on polar glacier surfaces are found dispersed on the ice surface, or concentrated in cryoconite holes and cryolakes, which are accumulations of debris covered by a layer of ice for some or all of the year. The ice lid limits the penetration of photosynthetically available radiation (PAR) to the sediment layer, since the ice attenuates up to 99% of incoming radiation. This suite of field and laboratory experiments demonstrates that PAR is an important control on primary production in cryoconite and cryolake ecosystems. Increased light intensity increased efficiency of primary production in controlled laboratory incubations of debris from the surface of Joyce Glacier, McMurdo Dry Valleys, Antarctica. However, when light intensity was increased to levels near that received on the ice surface, without the protection of an ice lid, efficiency decreased and measurements of photophysiology showed that the communities suffered light stress. The communities are therefore well adapted to low light levels. Comparison with Arctic cryoconite communities, which are typically not covered by an ice lid for the majority of the ablation season, showed that these organisms were also stressed by high light, so they must employ strategies to protect against photodamage. PMID:27095815

Absolute molecular weight determination of hypromellose acetate succinate by size exclusion chromatography: use of a multi angle laser light scattering detector and a mixed solvent.

PubMed

Chen, Raymond; Ilasi, Nicholas; Sekulic, Sonja S

2011-12-05

Molecular weight distribution is an important quality attribute for hypromellose acetate succinate (HPMCAS), a pharmaceutical excipient used in spray-dried dispersions. Our previous study showed that neither relative nor universal calibration method of size exclusion chromatography (SEC) works for HPMCAS polymers. We here report our effort to develop a SEC method using a mass sensitive multi angle laser light scattering detector (MALLS) to determine molecular weight distributions of HPMCAS polymers. A solvent screen study reveals that a mixed solvent (60:40%, v/v 50mM NaH(2)PO(4) with 0.1M NaNO(3) buffer: acetonitrile, pH* 8.0) is the best for HPMCAS-LF and MF sub-classes. Use of a mixed solvent creates a challenging condition for the method that uses refractive index detector. Therefore, we thoroughly evaluated the method performance and robustness. The mean weight average molecular weight of a polyethylene oxide standard has a 95% confidence interval of (28,443-28,793) g/mol vs. 28,700g/mol from the Certificate of Analysis. The relative standard deviations of average molecular weights for all polymers are 3-6%. These results and the Design of Experiments study demonstrate that the method is accurate and robust. Copyright © 2011 Elsevier B.V. All rights reserved.

Polymerization contraction stress in dentin adhesives bonded to dentin and enamel.

PubMed

Hashimoto, Masanori; de Gee, Anton J; Feilzer, Albert J

2008-10-01

In a previous study on of polymerization contraction stress determinations of adhesives bonded to dentin a continuous decline of stress was observed after the adhesives had been light-cured. The decline was ascribed to stress relief caused by diffusion into the adhesive layer of water and/or solvents, left in the impregnated dentin surface after drying and/or evaporation in the application procedure. The purpose of the present study was to test the hypothesis that the contraction stress of adhesives bonded to enamel will not decline after light-curing, based on the assumption that water and/or solvents are more efficiently removed from impregnated enamel surfaces in the drying and/or evaporation step. Contraction stress was determined in a tensilometer for three total-etching adhesives Scotchbond multi-purpose, Single bond and One-step plus and four self-etching adhesives Clearfil SE Bond, Clearfil Protect Bond, AdheSE, and Xeno III. The adhesives were placed in a thin layer between a glass plate and a flat dentin or enamel surface pre-treated with phosphoric acid or self-etching primer and light-cured under constrained conditions. All adhesives bonded to enamel showed a stress decline, but significantly less than for dentin with the exception of two self-etching adhesives. The greatest decline was found for the total-etching adhesive systems bonded to dentin. The presence of hydrophobic monomers in the adhesives had a significant influence on the decline. The experiments indicate that fluids are withdrawn from the resin impregnated tooth structures, which may result in small defects in the tooth-resin interfaces.

A Multi-Pronged Plan

ERIC Educational Resources Information Center

Starkman, Neal

2007-01-01

As schools adopt new and varied technologies to protect the campus community, the need to look at security tools in terms of a comprehensive, layered, and integrated strategy, becomes clear. This article discusses how schools are using these security tools.

Light environment change induces differential expression of guppy opsins in a multi-generational evolution experiment.

PubMed

Kranz, Alexandrea M; Forgan, Leonard G; Cole, Gemma L; Endler, John A

2018-06-19

Light environments critically impact species that rely on vision to survive and reproduce. Animal visual systems must accommodate changes in light that occur from minutes to years, yet the mechanistic basis of their response to spectral (color) changes is largely unknown. Here we used a laboratory experiment where replicate guppy populations were kept under three different light environments for up to 8-12 generations to explore possible differences in the expression levels of nine guppy opsin genes. Previous evidence for opsin expression-light environment 'tuning' has been either correlative or focused exclusively on the relationship between the light environment and opsin expression over one or two generations. In our multi-generation experiment, the relative expression levels of nine different guppy opsin genes responded differently to light environment changes: some did not respond, while others differed due to phenotypic plasticity. Moreover, for the LWS-1 opsin we found that, while we observed a wide range of plastic responses under different light conditions, common plastic responses (where the population replicates all followed the same trajectory) occurred only after multigenerational exposure to different light environments. Taken together this suggests that opsin expression plasticity plays an important role in light environment 'tuning' in different light environments on different time scales, and, in turn, has important implications for both visual system function and evolution. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Progressive Label Fusion Framework for Multi-atlas Segmentation by Dictionary Evolution

PubMed Central

Song, Yantao; Wu, Guorong; Sun, Quansen; Bahrami, Khosro; Li, Chunming; Shen, Dinggang

2015-01-01

Accurate segmentation of anatomical structures in medical images is very important in neuroscience studies. Recently, multi-atlas patch-based label fusion methods have achieved many successes, which generally represent each target patch from an atlas patch dictionary in the image domain and then predict the latent label by directly applying the estimated representation coefficients in the label domain. However, due to the large gap between these two domains, the estimated representation coefficients in the image domain may not stay optimal for the label fusion. To overcome this dilemma, we propose a novel label fusion framework to make the weighting coefficients eventually to be optimal for the label fusion by progressively constructing a dynamic dictionary in a layer-by-layer manner, where a sequence of intermediate patch dictionaries gradually encode the transition from the patch representation coefficients in image domain to the optimal weights for label fusion. Our proposed framework is general to augment the label fusion performance of the current state-of-the-art methods. In our experiments, we apply our proposed method to hippocampus segmentation on ADNI dataset and achieve more accurate labeling results, compared to the counterpart methods with single-layer dictionary. PMID:26942233

Progressive Label Fusion Framework for Multi-atlas Segmentation by Dictionary Evolution.

PubMed

Song, Yantao; Wu, Guorong; Sun, Quansen; Bahrami, Khosro; Li, Chunming; Shen, Dinggang

2015-10-01

Accurate segmentation of anatomical structures in medical images is very important in neuroscience studies. Recently, multi-atlas patch-based label fusion methods have achieved many successes, which generally represent each target patch from an atlas patch dictionary in the image domain and then predict the latent label by directly applying the estimated representation coefficients in the label domain. However, due to the large gap between these two domains, the estimated representation coefficients in the image domain may not stay optimal for the label fusion. To overcome this dilemma, we propose a novel label fusion framework to make the weighting coefficients eventually to be optimal for the label fusion by progressively constructing a dynamic dictionary in a layer-by-layer manner, where a sequence of intermediate patch dictionaries gradually encode the transition from the patch representation coefficients in image domain to the optimal weights for label fusion. Our proposed framework is general to augment the label fusion performance of the current state-of-the-art methods. In our experiments, we apply our proposed method to hippocampus segmentation on ADNI dataset and achieve more accurate labeling results, compared to the counterpart methods with single-layer dictionary.

Label-free detection of DNA using a light-addressable potentiometric sensor modified with a positively charged polyelectrolyte layer

NASA Astrophysics Data System (ADS)

Wu, Chunsheng; Bronder, Thomas; Poghossian, Arshak; Werner, Carl Frederik; Schöning, Michael J.

2015-03-01

A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al-p-Si-SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent-voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout.A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al-p-Si-SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent-voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07225a

Near infrared laser penetration and absorption in human skin

NASA Astrophysics Data System (ADS)

Nasouri, Babak; Murphy, Thomas E.; Berberoglu, Halil

2014-02-01

For understanding the mechanisms of low level laser/light therapy (LLLT), accurate knowledge of light interaction with tissue is necessary. In this paper, we present a three dimensional, multi-layer Monte Carlo simulation tool for studying light penetration and absorption in human skin. The skin is modeled as a three-layer participating medium, namely epidermis, dermis, and subcutaneous, where its geometrical and optical properties are obtained from the literature. Both refraction and reflection are taken into account at the boundaries according to Snell's law and Fresnel relations. A forward Monte Carlo method was implemented and validated for accurately simulating light penetration and absorption in absorbing and anisotropically scattering media. Local profiles of light penetration and volumetric absorption densities were simulated for uniform as well as Gaussian profile beams with different spreads at 155 mW average power over the spectral range from 1000 nm to 1900 nm. The results show the effects of beam profiles and wavelength on the local fluence within each skin layer. Particularly, the results identify different wavelength bands for targeted deposition of power in different skin layers. Finally, we show that light penetration scales well with the transport optical thickness of skin. We expect that this tool along with the results presented will aid researchers resolve issues related to dose and targeted delivery of energy in tissues for LLLT.

Thickness determination of polymeric multilayer surface protection systems for concrete by means of pulse thermography

NASA Astrophysics Data System (ADS)

Altenburg, S. J.; Krankenhagen, R.; Bavendiek, F.

2017-02-01

For thickness determination of polymer based surface protection systems for concrete surfaces, so far only destructive measurement techniques are available. Pulse thermography appears to be well suited for non-destructive thickness evaluation in these systems. Here, we present first results of the development of a respective measurement and analysis procedure. Since surface protection systems consist of a number of layers, a model for the calculation of the surface temperature of a multi-layer structure on a semi-infinite (concrete) substrate in pulse thermography setup was developed. It considers semitransparency of the upmost layer and thermal losses at the surface. It also supports the use of an arbitrary temporal shape of the heating pulse to properly describe the measurement conditions for different heat sources. Simulations for one and three layers on the substrate are presented and first results from fitting the model to experimental data for thickness determination and verification of the model are presented.

Is Your Center Burglar/Vandal Proofed? Guidelines for Protecting Your Center.

ERIC Educational Resources Information Center

Adams, Shawn

1998-01-01

Identifies specific steps that child care centers can take to reduce the chances of burglary and vandalism. Differentiates loss prevention, loss control, and risk financing. Includes discussion of layering defenses, perimeter protection, security lighting, building surface security, locks, and alarm systems. Discusses the importance of reducing…

Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

PubMed

Cao, Zi-Quan; Wang, Guo-Jie

2016-06-01

Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

External Tank Program - Legacy of Success

NASA Technical Reports Server (NTRS)

Pilet, Jeffery C.; Diecidue-Conners, Dawn; Worden, Michelle; Guillot, Michelle; Welzyn, Kenneth

2011-01-01

The largest single element of Space Shuttle is the External Tank (ET), which serves as the structural backbone of the vehicle during ascent and provides liquid propellants to the Orbiter s three Main Engines. The ET absorbs most of the seven million pounds of thrust exerted by the Solid Rocket Boosters and Main Engines. The design evolved through several block changes, reducing weight each time. Because the tank flies to orbital velocity with the Space Shuttle Orbiter, minimization of weight is mandatory, to maximize payload performance. The initial configuration, the standard weight tank, weighed 76,000 pounds and was an aluminum 2219 structure. The light weight tank weighed 66,000 pounds and flew 86 missions. The super light weight tank weighed 58,500 pounds and was primarily an aluminum-lithium structure. The final configuration and low weight enabled system level performance sufficient for assembly of the International Space Station in a high inclination orbit, vital for international cooperation. Another significant challenge was the minimization of ice formation on the cryogenic tanks. This was essential due to the system configuration and the choice of ceramic thermal protection system materials on the Orbiter. Ice would have been a major debris hazard. Spray on foam insulation materials served multiple functions including thermal insulation, conditioning of cryogenic propellants, and thermal protection for the tank structure during ascent and entry. The tank is large, and unique manufacturing facilities, tooling, and handling, and transportation operations were developed. Weld processes and tooling evolved with the design as it matured through several block changes. Non Destructive Evaluation methods were used to assure integrity of welds and thermal protection system materials. The aluminum-lithium alloy was used near the end of the program and weld processes and weld repair techniques had to be refined. Development and implementation of friction stir welding was a substantial technology development incorporated during the Program. Automated thermal protection system application processes were developed for the majority of the tank surface. Material obsolescence was an issue throughout the multi-decade program. Process controls were implemented to assure cleanliness in the production environment, to control contaminants, and to preclude corrosion. Each tank was accepted via rigorous inspections, including non-destructive evaluation techniques, proof testing, and all systems testing. In the post STS-107 era, the project focused on ascent debris risk reduction. This was accomplished via stringent process controls, post flight assessment using substantially improved imagery, and selective redesigns. These efforts were supported with a number of test programs to simulate combined environments. The debris risk was reduced by two orders of magnitude. During this time a major natural disaster was overcome when hurricane Katrina damaged the manufacturing facility. Numerous lessons from these efforts, the manufacturing and material processing issues, the key design features, and evolution of the design will be discussed.

Radiative habitable zones in martian polar environments.

PubMed

Córdoba-Jabonero, Carmen; Zorzano, María-Paz; Selsis, Franck; Patel, Manish R; Cockell, Charles S

2005-06-01

The biologically damaging solar ultraviolet (UV) radiation (quantified by the DNA-weighted dose) reaches the martian surface in extremely high levels. Searching for potentially habitable UV-protected environments on Mars, we considered the polar ice caps that consist of a seasonally varying CO2 ice cover and a permanent H2O ice layer. It was found that, though the CO2 ice is insufficient by itself to screen the UV radiation, at approximately 1 m depth within the perennial H2O ice the DNA-weighted dose is reduced to terrestrial levels. This depth depends strongly on the optical properties of the H2O ice layers (for instance snow-like layers). The Earth-like DNA-weighted dose and Photosynthetically Active Radiation (PAR) requirements were used to define the upper and lower limits of the northern and southern polar Radiative Habitable Zone (RHZ) for which a temporal and spatial mapping was performed. Based on these studies we conclude that photosynthetic life might be possible within the ice layers of the polar regions. The thickness varies along each martian polar spring and summer between approximately 1.5 and 2.4 m for H2O ice-like layers, and a few centimeters for snow-like covers. These martian Earth-like radiative habitable environments may be primary targets for future martian astrobiological missions. Special attention should be paid to planetary protection, since the polar RHZ may also be subject to terrestrial contamination by probes. c2004 Elsevier Inc. All rights reserved.

Removal of the blue component of light significantly decreases retinal damage after high intensity exposure.

PubMed

Vicente-Tejedor, Javier; Marchena, Miguel; Ramírez, Laura; García-Ayuso, Diego; Gómez-Vicente, Violeta; Sánchez-Ramos, Celia; de la Villa, Pedro; Germain, Francisco

2018-01-01

Light causes damage to the retina (phototoxicity) and decreases photoreceptor responses to light. The most harmful component of visible light is the blue wavelength (400-500 nm). Different filters have been tested, but so far all of them allow passing a lot of this wavelength (70%). The aim of this work has been to prove that a filter that removes 94% of the blue component may protect the function and morphology of the retina significantly. Three experimental groups were designed. The first group was unexposed to light, the second one was exposed and the third one was exposed and protected by a blue-blocking filter. Light damage was induced in young albino mice (p30) by exposing them to white light of high intensity (5,000 lux) continuously for 7 days. Short wavelength light filters were used for light protection. The blue component was removed (94%) from the light source by our filter. Electroretinographical recordings were performed before and after light damage. Changes in retinal structure were studied using immunohistochemistry, and TUNEL labeling. Also, cells in the outer nuclear layer were counted and compared among the three different groups. Functional visual responses were significantly more conserved in protected animals (with the blue-blocking filter) than in unprotected animals. Also, retinal structure was better kept and photoreceptor survival was greater in protected animals, these differences were significant in central areas of the retina. Still, functional and morphological responses were significantly lower in protected than in unexposed groups. In conclusion, this blue-blocking filter decreases significantly photoreceptor damage after exposure to high intensity light. Actually, our eyes are exposed for a very long time to high levels of blue light (screens, artificial light LED, neons…). The potential damage caused by blue light can be palliated.

A joint precoding scheme for indoor downlink multi-user MIMO VLC systems

NASA Astrophysics Data System (ADS)

Zhao, Qiong; Fan, Yangyu; Kang, Bochao

2017-11-01

In this study, we aim to improve the system performance and reduce the implementation complexity of precoding scheme for visible light communication (VLC) systems. By incorporating the power-method algorithm and the block diagonalization (BD) algorithm, we propose a joint precoding scheme for indoor downlink multi-user multi-input-multi-output (MU-MIMO) VLC systems. In this scheme, we apply the BD algorithm to eliminate the co-channel interference (CCI) among users firstly. Secondly, the power-method algorithm is used to search the precoding weight for each user based on the optimal criterion of signal to interference plus noise ratio (SINR) maximization. Finally, the optical power restrictions of VLC systems are taken into account to constrain the precoding weight matrix. Comprehensive computer simulations in two scenarios indicate that the proposed scheme always has better bit error rate (BER) performance and lower computation complexity than that of the traditional scheme.

Concepts for the development of light-weight composite structures for rotor burst containment

NASA Technical Reports Server (NTRS)

Holmes, A. G.

1977-01-01

A set of hypotheses is established as to what variables might control the design of a weight-efficient protective device. A particular experiment for evaluating the hypotheses and materials was designed. The design and methods for the analysis of results are described.

Development of Ultraviolet (UV) Radiation Protective Fabric Using Combined Electrospinning and Electrospraying Technique

NASA Astrophysics Data System (ADS)

Sinha, Mukesh Kumar; Das, B. R.; Kumar, Kamal; Kishore, Brij; Prasad, N. Eswara

2017-06-01

The article reports a novel technique for functionization of nanoweb to develop ultraviolet (UV) radiation protective fabric. UV radiation protection effect is produced by combination of electrospinning and electrospraying technique. A nanofibrous web of polyvinylidene difluoride (PVDF) coated on polypropylene nonwoven fabric is produced by latest nanospider technology. Subsequently, web is functionalized by titanium dioxide (TiO2). The developed web is characterized for evaluation of surface morphology and other functional properties; mechanical, chemical, crystalline and thermal. An optimal (judicious) nanofibre spinning condition is achieved and established. The produced web is uniformly coated by defect free functional nanofibres in a continuous form of useable textile structural membrane for ultraviolet (UV) protective clothing. This research initiative succeeds in preparation and optimization of various nanowebs for UV protection. Field Emission Scanning Electron Microscope (FESEM) result reveals that PVDF webs photo-degradative behavior is non-accelerated, as compared to normal polymeric grade fibres. Functionalization with TiO2 has enhanced the photo-stability of webs. The ultraviolet protection factor of functionalized and non-functionalized nanowebs empirically evaluated to be 65 and 24 respectively. The developed coated layer could be exploited for developing various defence, para-military and civilian UV protective light weight clothing (tent, covers and shelter segments, combat suit, snow bound camouflaging nets). This research therefore, is conducted in an attempt to develop a scientific understanding of PVDF fibre coated webs for photo-degradation and applications for defence protective textiles. This technological research in laboratory scale could be translated into bulk productionization.

Broadband integrated polarization rotator using three-layer metallic grating structures

DOE PAGES

Fan, Ren -Hao; Liu, Dong; Peng, Ru -Wen; ...

2018-01-05

In this work, we demonstrate broadband integrated polarization rotator (IPR) with a series of three-layer rotating metallic grating structures. This transmissive optical IPR can conveniently rotate the polarization of linearly polarized light to any desired directions at different spatial locations with high conversion efficiency, which is nearly constant for different rotation angles. The linear polarization rotation originates from multi-wave interference in the three-layer grating structure. As a result, we anticipate that this type of IPR will find wide applications in analytical chemistry, biology, communication technology, imaging, etc.

Broadband integrated polarization rotator using three-layer metallic grating structures

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

Fan, Ren -Hao; Liu, Dong; Peng, Ru -Wen

In this work, we demonstrate broadband integrated polarization rotator (IPR) with a series of three-layer rotating metallic grating structures. This transmissive optical IPR can conveniently rotate the polarization of linearly polarized light to any desired directions at different spatial locations with high conversion efficiency, which is nearly constant for different rotation angles. The linear polarization rotation originates from multi-wave interference in the three-layer grating structure. As a result, we anticipate that this type of IPR will find wide applications in analytical chemistry, biology, communication technology, imaging, etc.

Understanding charge transfer dynamics in QDs-TiO2 nanorod array photoanodes for solar fuel generation

NASA Astrophysics Data System (ADS)

Li, Jiangtian; McClure, Joshua P.; Fu, Richard; Jiang, Rongzhong; Chu, Deryn

2018-01-01

Harvesting light to drive water splitting for hydrogen generation is an attractive approach to satisfy the urgent energy demands. The design and fabrication of photoelectrode materials that are able to harvest sunlight is an important scientific undertaking. In this study, a two-quantum-dot (QD) layer is developed to decorate one-dimensional TiO2 nanorod arrays, which are subsequently utilized as photoanodes to harvest the wide-spectrum sunlight for water splitting. The QD-coated TiO2 nanorod arrays extend the light absorption range from the UV into the visible region yielding increased solar-to-hydrogen efficiencies. Transient photocurrent decay measurements demonstrate that the multi-layer CdSe-CdS QDs deposited onto the TiO2 nanorod arrays result in a stepwise band alignment that not only improves the hole extraction but also facilitates electron injection from the QDs to TiO2 rods. Moreover, the multi-heterojunction photoanode introduces interfacial states that act as recombination centers to trap the photogenerated electrons.

Calibrating the interaction matrix for the LINC-NIRVANA high layer wavefront sensor.

PubMed

Zhang, Xianyu; Arcidiacono, Carmelo; Conrad, Albert R; Herbst, Thomas M; Gaessler, Wolfgang; Bertram, Thomas; Ragazzoni, Roberto; Schreiber, Laura; Diolaiti, Emiliano; Kuerster, Martin; Bizenberger, Peter; Meschke, Daniel; Rix, Hans-Walter; Rao, Changhui; Mohr, Lars; Briegel, Florian; Kittmann, Frank; Berwein, Juergen; Trowitzsch, Jan

2012-03-26

LINC-NIRVANA is a near-infrared Fizeau interferometric imager that will operate at the Large Binocular Telescope. In preparation for the commissioning of this instrument, we conducted experiments for calibrating the high-layer wavefront sensor of the layer-oriented multi-conjugate adaptive optics system. For calibrating the multi-pyramid wavefront sensor, four light sources were used to simulate guide stars. Using this setup, we developed the push-pull method for calibrating the interaction matrix. The benefits of this method over the traditional push-only method are quantified, and also the effects of varying the number of push-pull frames over which aberrations are averaged is reported. Finally, we discuss a method for measuring mis-conjugation between the deformable mirror and the wavefront sensor, and the proper positioning of the wavefront sensor detector with respect to the four pupil positions.

40 CFR 86.129-00 - Road load power, test weight, and inertia weight class determination.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Road load power, test weight, and... Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles; Test Procedures § 86.129-00 Road load... running loss testing. Paragraphs (e) and (f) of this section are applicable to vehicles from engine...

40 CFR 86.129-00 - Road load power, test weight, and inertia weight class determination.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Road load power, test weight, and... Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles; Test Procedures § 86.129-00 Road load... running loss testing. Paragraphs (e) and (f) of this section are applicable to vehicles from engine...

40 CFR 86.129-00 - Road load power, test weight, and inertia weight class determination.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Road load power, test weight, and... Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles; Test Procedures § 86.129-00 Road load... running loss testing. Paragraphs (e) and (f) of this section are applicable to vehicles from engine...

40 CFR 86.129-00 - Road load power, test weight, and inertia weight class determination.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Road load power, test weight, and... Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles; Test Procedures § 86.129-00 Road load... running loss testing. Paragraphs (e) and (f) of this section are applicable to vehicles from engine...

40 CFR 86.129-00 - Road load power, test weight, and inertia weight class determination.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Road load power, test weight, and... Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles; Test Procedures § 86.129-00 Road load... running loss testing. Paragraphs (e) and (f) of this section are applicable to vehicles from engine...

A numerical study on the charge transport in TPD/Alq3-based organic light emitting diodes.

PubMed

Kim, K S; Hwang, Y W; Lee, H G; Won, T Y

2014-08-01

We report our simulation study on the charge transport characteristic of the multi-layer structure for organic light emitting diodes (OLEDs). We performed a numerical simulation on a multilayer structure comprising a hole transport layer (HTL), an emission layer (EML), and an electron transport layer (ETL) between both electrodes. The material of the HTL is TPD (N,N'-Bis (3-methylphenyl)-N,N'-bis(phenyl) benzidine), and the ETL includes Alq3 (Tris (8-hyroxyquinolinato) aluminium). Here, we investigated the parameters such as recombination rates which influence the efficiency of the charge transport between layers in bilayer OLEDs. We also analyzed a transient response during the turn on/off period and the carrier transport in accordance with the variation of the injection barrier and applied voltage. In addition, our numerical simulation revealed that the insertion of the EML affects the photonic characteristics in bilayer structure and also the efficiency due to the difference in the internal barrier height.

Nanotube Heterojunctions and Endo-Fullerenes for Nanoelectronics

NASA Technical Reports Server (NTRS)

Srivastava, Deepak; Menon, M.; Andriotis, Antonis; Cho, K.; Park, Jun; Biegel, Bryan A. (Technical Monitor)

2002-01-01

Topics discussed include: (1) Light-Weight Multi-Functional Materials: Nanomechanics; Nanotubes and Composites; Thermal/Chemical/Electrical Characterization; (2) Biomimetic/Revolutionary Concepts: Evolutionary Computing and Sensing; Self-Heating Materials; (3) Central Computing System: Molecular Electronics; Materials for Quantum Bits; and (4) Molecular Machines.

Characterization and migration of oil and solids in oily sludge during centrifugation.

PubMed

Wang, Jun; Han, Xu; Huang, Qunxing; Ma, Zengyi; Chi, Yong; Yan, Jianhua

2018-05-01

The migration behaviors of oil, water and solids in sludge during centrifugation were elaborated. Size distribution, surface topography and lypohydrophilic properties were studied in detail. The average size of solids was 61 μm in original sludge, 31 μm in upper layer and 235 μm in bottom layer. The result shows that solvent is essential to separate oil phase into molecular light and weight fractions during centrifugation. With solvent/oil ratio increases from 1:2, 1:1, 2:1 to 5:1, molecular weight in upper layer decreases from 1044, 1043, 1020 to 846 combined with that in bottom layer increases. A model was proposed to calculate the oil residue content in solid phases after sedimentation. The findings of this paper provide information for optimizing the oil recovery and clean treatment.

An SMS (single mode - multi mode - single mode) fiber structure for vibration sensing

NASA Astrophysics Data System (ADS)

Waluyo, T. B.; Bayuwati, D.

2017-04-01

We describe an SMS (single mode - multi mode - single mode) fiber structure to be used in a vibration sensing system. The fiber structure was fabricated by splicing a section (about 300 mm in length) of a step index multi mode fiber between two single mode fibers obtained from a communication grade fiber patchcord. Interference between higher order modes occurs while light from a narrow band light source travels along the multi mode fiber. When the multi mode fiber vibrates, the refractive index profile is changed because of the photo-elastics effect and the amplitude of the interference pattern is changed accordingly. To simulate a vibrating structure we used a loudspeaker to vibrate a wooden table. By using a digital oscilloscope, we recorded and analysed the vibrating signals obtained from the SMS fiber structure as well as from a GS-32CT geophone for referencing. We observed that this SMS fiber structure was potential to be used in a vibration sensing system with a measurement range from 30 to 180 Hz with inherent optical fiber sensor advantages such as light weight, immune to electromagnetic interference, and no electricity in the sensing part.

IAU Resolution 2009 B5 - Commission 50 Draft Action Plan - Presentation and Discussion

NASA Astrophysics Data System (ADS)

Green, R. F.

2015-03-01

IAU Resolution 2009 B5 calls on IAU members to protect the public's right to an unpolluted night sky as well as the astronomical quality of the sky around major research observatories. The multi-pronged approach of Commission 50 includes working with the lighting industry for appropriate products from the solid state revolution, arming astronomers with training and materials for presentation, selective endorsement of key protection issues, cooperation with several other IAU commissions for education and outreach, and provision of clear quantitative priorities for outdoor lighting standards.

Ammunition Suite for the FCS Multi-role Armament and Ammunition System (MRAAS)

DTIC Science & Technology

2001-06-20

Cards Large Scale Gap Test (LSGT) Exploding Foil Initiator ( EFI ) Effort 19 Slow Burning Layer Fast Burning Layer FASTCORE Nitramines ETPEs RDX CL20...Center Burst Charge 48 M80 Grenades With Center Burst Charge ü Trade off performance with size, weight, etc. ü Develop initial space claim for...submunition ü Dynamic Analysis of projectile for different submunitions MRAAS Trades underway • Accomplishments – Initial meetings with TRADOC, Ft Knox and Ft

Groundwater vulnerability assessment for organic compounds: fuzzy multi-criteria approach for Mexico city.

PubMed

Mazari-Hiriart, Marisa; Cruz-Bello, Gustavo; Bojórquez-Tapia, Luis A; Juárez-Marusich, Lourdes; Alcantar-López, Georgina; Marín, Luis E; Soto-Galera, Ernesto

2006-03-01

This study was based on a groundwater vulnerability assessment approach implemented for the Mexico City Metropolitan Area (MCMA). The approach is based on a fuzzy multi-criteria procedure integrated in a geographic information system. The approach combined the potential contaminant sources with the permeability of geological materials. Initially, contaminant sources were ranked by experts through the Analytic Hierarchy Process. An aggregated contaminant sources map layer was obtained through the simple additive weighting method, using a scalar multiplication of criteria weights and binary maps showing the location of each source. A permeability map layer was obtained through the reclassification of a geology map using the respective hydraulic conductivity values, followed by a linear normalization of these values against a compatible scale. A fuzzy logic procedure was then applied to transform and combine the two map layers, resulting in a groundwater vulnerability map layer of five classes: very low, low, moderate, high, and very high. Results provided a more coherent assessment of the policy-making priorities considered when discussing the vulnerability of groundwater to organic compounds. The very high and high vulnerability areas covered a relatively small area (71 km(2) or 1.5% of the total study area), allowing the identification of the more critical locations. The advantage of a fuzzy logic procedure is that it enables the best possible use to be made of the information available regarding groundwater vulnerability in the MCMA.

High temperature insulation barrier composite

NASA Technical Reports Server (NTRS)

Onstott, Joseph W. (Inventor)

1989-01-01

A composite material suitable for providing insulation for the nozzle structure of the Space Shuttle and other similar surfaces is disclosed. The composite layer is comprised of an outer skin layer of nickel chromium and an interleaved inner region comprising a top layer of nickel chromium foil which acts as a primary convective shield. There are at least two layers of alumina batting adjacent to the layers of silicon carbide fabric. An additional layer of nickel chromium foil is used as a secondary convective shield. The composite is particularly advantageous for use as nozzle insulation because of its ability to withstand high reentry temperatures, its flexibility, oxidation resistance, low conductivity, and light weight.

Proving the viability of manufacturing of multi-layer steel/vanadium alloy/steel composite tubes by numerical simulations and experiment

NASA Astrophysics Data System (ADS)

Nechaykina, T.; Nikulin, S.; Rozhnov, A.; Molotnikov, A.; Zavodchikov, S.; Estrin, Y.

2018-05-01

Vanadium alloys are promising structural materials for fuel cladding tubes for fast-neutron reactors. However, high solubility of oxygen and nitrogen in vanadium alloys at operating temperatures of 700 °C limits their application. In this work, we present a novel composite structure consisting of vanadium alloy V-4Ti-4Cr (provides high long-term strength of the material) and stainless steel Fe-0.2C-13Cr (as a corrosion resistant protective layer). It is produced by co-extrusion of these materials forming a three-layered tube. Finite element simulations were utilised to explore the influence of the various co-extrusion parameters on manufacturability of multi-layered tubes. Experimental verification of the numerical modelling was performed using co-extrusion with the process parameters suggested by the numerical simulations. Scanning electron microscopy and microhardness measurements revealed a defect-free diffusion layer at the interfaces between both materials indicating a good quality bonding for these co-extrusion conditions.

Advantages of an InGaN-based light emitting diode with a p-InGaN/p-GaN superlattice hole accumulation layer

NASA Astrophysics Data System (ADS)

Liu, Chao; Ren, Zhi-Wei; Chen, Xin; Zhao, Bi-Jun; Wang, Xing-Fu; Yin, Yi-An; Li, Shu-Ti

2013-05-01

P-InGaN/p-GaN superlattices (SLs) are developed for a hole accumulation layer (HAL) of a blue light emitting diode (LED). Free hole concentration as high as 2.6 × 1018 cm-3 is achieved by adjusting the Cp2Mg flow rate during the growth of p-InGaN/p-GaN SLs. The p-InGaN/p-GaN SLs with appropriate Cp2Mg flow rates are then incorporated between the multi-quantum well and AlGaN electron blocking layer as an HAL, which leads to the enhancement of light output power by 29% at 200 mA, compared with the traditional LED without such SL HAL. Meanwhile, the efficiency droop is also effectively alleviated in the LED with the SL HAL. The improved performance is attributed to the increased hole injection efficiency, and the reduced electron leakage by inserting the p-type SL HAL.

White organic light-emitting diodes with ultra-thin mixed emitting layer

NASA Astrophysics Data System (ADS)

Jeon, T.; Forget, S.; Chenais, S.; Geffroy, B.; Tondelier, D.; Bonnassieux, Y.; Ishow, E.

2012-02-01

White light can be obtained from Organic Light Emitting Diodes by mixing three primary colors, (i.e. red, green and blue) or two complementary colors in the emissive layer. In order to improve the efficiency and stability of the devices, a host-guest system is generally used as an emitting layer. However, the color balance to obtain white light is difficult to control and optimize because the spectrum is very sensitive to doping concentration (especially when a small amount of material is used). We use here an ultra-thin mixed emitting layer (UML) deposited by thermal evaporation to fabricate white organic light emitting diodes (WOLEDs) without co-evaporation. The UML was inserted in the hole-transporting layer consisting of 4, 4'-bis[N-(1-naphtyl)-N-phenylamino]biphenyl (α-NPB) instead of using a conventional doping process. The UML was formed from a single evaporation boat containing a mixture of two dipolar starbust triarylamine molecules (fvin and fcho) presenting very similar structures and thermal properties and emitting in complementary spectral regions (orange and blue respectively) and mixed according to their weight ratio. The composition of the UML specifically allows for fine tuning of the emission color despite its very thin thickness down to 1 nm. Competitive energy transfer processes from fcho and the host interface toward fvin are key parameters to control the relative intensity between red and blue emission. White light with very good CIE 1931 color coordinate (0.34, 0.34) was obtained by simply adjusting the UML film composition.

Thermal Imaging for Assessment of Electron-Beam Free Form Fabrication (EBF(sup 3)) Additive Manufacturing Welds

NASA Technical Reports Server (NTRS)

Zalameda, Joseph N.; Burke, Eric R.; Hafley, Robert A.; Taminger, Karen M.; Domack, Christopher S.; Brewer, Amy R.; Martin, Richard E.

2013-01-01

Additive manufacturing is a rapidly growing field where 3-dimensional parts can be produced layer by layer. NASA s electron beam free-form fabrication (EBF(sup 3)) technology is being evaluated to manufacture metallic parts in a space environment. The benefits of EBF(sup 3) technology are weight savings to support space missions, rapid prototyping in a zero gravity environment, and improved vehicle readiness. The EBF(sup 3) system is composed of 3 main components: electron beam gun, multi-axis position system, and metallic wire feeder. The electron beam is used to melt the wire and the multi-axis positioning system is used to build the part layer by layer. To insure a quality weld, a near infrared (NIR) camera is used to image the melt pool and solidification areas. This paper describes the calibration and application of a NIR camera for temperature measurement. In addition, image processing techniques are presented for weld assessment metrics.

Superscattering of light optimized by a genetic algorithm

NASA Astrophysics Data System (ADS)

Mirzaei, Ali; Miroshnichenko, Andrey E.; Shadrivov, Ilya V.; Kivshar, Yuri S.

2014-07-01

We analyse scattering of light from multi-layer plasmonic nanowires and employ a genetic algorithm for optimizing the scattering cross section. We apply the mode-expansion method using experimental data for material parameters to demonstrate that our genetic algorithm allows designing realistic core-shell nanostructures with the superscattering effect achieved at any desired wavelength. This approach can be employed for optimizing both superscattering and cloaking at different wavelengths in the visible spectral range.

40 CFR 86.602-98 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Definitions. 86.602-98 Section 86.602... Auditing of New Light-Duty Vehicles, Light-Duty Trucks, and Heavy-Duty Vehicles § 86.602-98 Definitions..., inertia weight class, transmission type and gear ratios, axle ratio, and other parameters which may be...

40 CFR 86.602-98 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Definitions. 86.602-98 Section 86.602... Auditing of New Light-Duty Vehicles, Light-Duty Trucks, and Heavy-Duty Vehicles § 86.602-98 Definitions..., inertia weight class, transmission type and gear ratios, axle ratio, and other parameters which may be...

40 CFR 86.602-98 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Definitions. 86.602-98 Section 86.602... Auditing of New Light-Duty Vehicles, Light-Duty Trucks, and Heavy-Duty Vehicles § 86.602-98 Definitions..., inertia weight class, transmission type and gear ratios, axle ratio, and other parameters which may be...

40 CFR 86.602-98 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Definitions. 86.602-98 Section 86.602... Auditing of New Light-Duty Vehicles, Light-Duty Trucks, and Heavy-Duty Vehicles § 86.602-98 Definitions..., inertia weight class, transmission type and gear ratios, axle ratio, and other parameters which may be...

40 CFR 86.602-98 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Definitions. 86.602-98 Section 86.602... New Light-Duty Vehicles, Light-Duty Trucks, and Heavy-Duty Vehicles § 86.602-98 Definitions. Section..., inertia weight class, transmission type and gear ratios, axle ratio, and other parameters which may be...

Silicone Coating on Polyimide Sheet

NASA Technical Reports Server (NTRS)

Park, J. J.

1985-01-01

Silicone coatings applied to polyimide sheeting for variety of space-related applications. Coatings intended to protect flexible substrates of solar-cell blankets from degradation by oxygen atoms, electrons, plasmas, and ultraviolet light in low Earth orbit and outer space. Since coatings are flexible, generally useful in forming flexible laminates or protective layers on polyimide-sheet products.

Flexible high power-per-weight perovskite solar cells with chromium oxide-metal contacts for improved stability in air.

PubMed

Kaltenbrunner, Martin; Adam, Getachew; Głowacki, Eric Daniel; Drack, Michael; Schwödiauer, Reinhard; Leonat, Lucia; Apaydin, Dogukan Hazar; Groiss, Heiko; Scharber, Markus Clark; White, Matthew Schuette; Sariciftci, Niyazi Serdar; Bauer, Siegfried

2015-10-01

Photovoltaic technology requires light-absorbing materials that are highly efficient, lightweight, low cost and stable during operation. Organolead halide perovskites constitute a highly promising class of materials, but suffer limited stability under ambient conditions without heavy and costly encapsulation. Here, we report ultrathin (3 μm), highly flexible perovskite solar cells with stabilized 12% efficiency and a power-per-weight as high as 23 W g(-1). To facilitate air-stable operation, we introduce a chromium oxide-chromium interlayer that effectively protects the metal top contacts from reactions with the perovskite. The use of a transparent polymer electrode treated with dimethylsulphoxide as the bottom layer allows the deposition-from solution at low temperature-of pinhole-free perovskite films at high yield on arbitrary substrates, including thin plastic foils. These ultra-lightweight solar cells are successfully used to power aviation models. Potential future applications include unmanned aerial vehicles-from airplanes to quadcopters and weather balloons-for environmental and industrial monitoring, rescue and emergency response, and tactical security applications.

Flexible high power-per-weight perovskite solar cells with chromium oxide-metal contacts for improved stability in air

NASA Astrophysics Data System (ADS)

Kaltenbrunner, Martin; Adam, Getachew; Głowacki, Eric Daniel; Drack, Michael; Schwödiauer, Reinhard; Leonat, Lucia; Apaydin, Dogukan Hazar; Groiss, Heiko; Scharber, Markus Clark; White, Matthew Schuette; Sariciftci, Niyazi Serdar; Bauer, Siegfried

2015-10-01

Photovoltaic technology requires light-absorbing materials that are highly efficient, lightweight, low cost and stable during operation. Organolead halide perovskites constitute a highly promising class of materials, but suffer limited stability under ambient conditions without heavy and costly encapsulation. Here, we report ultrathin (3 μm), highly flexible perovskite solar cells with stabilized 12% efficiency and a power-per-weight as high as 23 W g-1. To facilitate air-stable operation, we introduce a chromium oxide-chromium interlayer that effectively protects the metal top contacts from reactions with the perovskite. The use of a transparent polymer electrode treated with dimethylsulphoxide as the bottom layer allows the deposition--from solution at low temperature--of pinhole-free perovskite films at high yield on arbitrary substrates, including thin plastic foils. These ultra-lightweight solar cells are successfully used to power aviation models. Potential future applications include unmanned aerial vehicles--from airplanes to quadcopters and weather balloons--for environmental and industrial monitoring, rescue and emergency response, and tactical security applications.

Glass-Based Transparent Conductive Electrode: Its Application to Visible-to-Ultraviolet Light-Emitting Diodes.

PubMed

Lee, Tae Ho; Kim, Kyeong Heon; Lee, Byeong Ryong; Park, Ju Hyun; Schubert, E Fred; Kim, Tae Geun

2016-12-28

Nitride-based ultraviolet light-emitting diodes (UV LEDs) are promising replacements for conventional UV lamps. However, the external quantum efficiency of UV LEDs is much lower than for visible LEDs due to light absorption in the p-GaN contact and electrode layers, along with p-AlGaN growth and doping issues. To minimize such absorption, we should obtain direct ohmic contact to p-AlGaN using UV-transparent ohmic electrodes and not use p-GaN as a contact layer. Here, we propose a glass-based transparent conductive electrode (TCE) produced using electrical breakdown (EBD) of an AlN thin film, and we apply the thin film to four (Al)GaN-based visible and UV LEDs with thin buffer layers for current spreading and damage protection. Compared to LEDs with optimal ITO contacts, our LEDs with AlN TCEs exhibit a lower forward voltage, higher light output power, and brighter light emission for all samples. The ohmic transport mechanism for current injection and spreading from the metal electrode to p-(Al)GaN layer via AlN TCE is also investigated by analyzing the p-(Al)GaN surface before and after EBD.

Effect of Amount of Carbon on the Reduction Efficiency of Iron Ore-Coal Composite Pellets in Multi-layer Bed Rotary Hearth Furnace (RHF)

NASA Astrophysics Data System (ADS)

Mishra, Srinibash; Roy, Gour Gopal

2016-08-01

The effect of carbon-to-hematite molar ratio has been studied on the reduction efficiency of iron ore-coal composite pellet reduced at 1523 K (1250 °C) for 20 minutes in a laboratory scale multi-layer bed rotary hearth furnace (RHF). Reduced pellets have been characterized through weight loss measurement, estimation of porosity, shrinkage, qualitative and quantitative phase analysis by XRD. Performance parameters such as the degree of reduction, metallization, carbon efficiency, productivity, and compressive strength have been calculated to compare the process efficacy at different carbon levels in the pellets. Pellets with optimum carbon-to-hematite ratio (C/Fe2O3 molar ratio = 1.66) that is much below the stoichiometric carbon required for direct reduction of hematite yielded maximum reduction, better carbon utilization, and productivity for all three layers. Top layer exhibited maximum reduction at comparatively lower carbon level (C/Fe2O3 molar ratio <2.33) in the pellet, while bottom layer exceeded top layer reduction at higher carbon level (C/Fe2O3 molar ratio >2.33). Correlation between degree of reduction and metallization indicated non-isothermal kinetics influenced by heat and mass transfer in multi-layer bed RHF. Compressive strength of the partially reduced pellet with optimum carbon content (C/Fe2O3 molar ratio = 1.66) showed that they could be potentially used as an alternate feed in a blast furnace or any other smelting reactor.

Composition and Molecular Weight Distribution of Carob Germ Proteins Fractions

USDA-ARS?s Scientific Manuscript database

Biochemical properties of carob germ proteins were analyzed using a combination of selective extraction, reversed-phase high performance liquid chromatography (RP-HPLC), size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALS) and electrophoretic analysis. Using a mo...

Multi-layer imager design for mega-voltage spectral imaging

NASA Astrophysics Data System (ADS)

Myronakis, Marios; Hu, Yue-Houng; Fueglistaller, Rony; Wang, Adam; Baturin, Paul; Huber, Pascal; Morf, Daniel; Star-Lack, Josh; Berbeco, Ross

2018-05-01

The architecture of multi-layer imagers (MLIs) can be exploited to provide megavoltage spectral imaging (MVSPI) for specific imaging tasks. In the current work, we investigated bone suppression and gold fiducial contrast enhancement as two clinical tasks which could be improved with spectral imaging. A method based on analytical calculations that enables rapid investigation of MLI component materials and thicknesses was developed and validated against Monte Carlo computations. The figure of merit for task-specific imaging performance was the contrast-to-noise ratio (CNR) of the gold fiducial when the CNR of bone was equal to zero after a weighted subtraction of the signals obtained from each MLI layer. Results demonstrated a sharp increase in the CNR of gold when the build-up component or scintillation materials and thicknesses were modified. The potential for low-cost, prompt implementation of specific modifications (e.g. composition of the build-up component) could accelerate clinical translation of MVSPI.

Runtime Performance Monitoring Tool for RTEMS System Software

NASA Astrophysics Data System (ADS)

Cho, B.; Kim, S.; Park, H.; Kim, H.; Choi, J.; Chae, D.; Lee, J.

2007-08-01

RTEMS is a commercial-grade real-time operating system that supports multi-processor computers. However, there are not many development tools for RTEMS. In this paper, we report new RTEMS-based runtime performance monitoring tool. We have implemented a light weight runtime monitoring task with an extension to the RTEMS APIs. Using our tool, software developers can verify various performance- related parameters during runtime. Our tool can be used during software development phase and in-orbit operation as well. Our implemented target agent is light weight and has small overhead using SpaceWire interface. Efforts to reduce overhead and to add other monitoring parameters are currently under research.

Flexible Foam Protection Materials for Constellation Space Suit Element Portable Life Support Subsystem Packaging Study

NASA Technical Reports Server (NTRS)

Tang, Henry H.; Orndoff, Evelyne S.; Thomas, Gretchen A.

2009-01-01

This paper discusses the effort in evaluating and selecting a light weight impact protection material for the Constellation Space Suit Element (CSSE) Portable Life Support Subsystem (PLSS) conceptual packaging study. A light weight material capable of holding and protecting the components inside the PLSS is required to demonstrate the viability of the flexible PLSS packaging concept. The material needs to distribute, dissipate, and absorb the impact energy of the PLSS falling on the lunar surface. It must also be very robust and function in the extreme lunar thermal vacuum environment for up to one hundred Extravehicular Activity (EVA) missions. This paper documents the performance requirements for selecting a foam protection material, and the methodologies for evaluating commercial off-the-shelf (COTS) foam protection materials. It also presents the materials properties test results and impact drop test results of the various foam materials evaluated in the study. The findings from this study suggest that a foam based flexible protection system is a viable solution for PLSS packaging. However, additional works are needed to optimize COTS foam properties or to develop a composite foam system that will meet all the performance requirements for the CSSE PLSS flexible packaging.

Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock.

PubMed

Chatterjee, Abhishek; Lamaze, Angélique; De, Joydeep; Mena, Wilson; Chélot, Elisabeth; Martin, Béatrice; Hardin, Paul; Kadener, Sebastian; Emery, Patrick; Rouyer, François

2018-06-07

The brain clock that drives circadian rhythms of locomotor activity relies on a multi-oscillator neuronal network. In addition to synchronizing the clock with day-night cycles, light also reformats the clock-driven daily activity pattern. How changes in lighting conditions modify the contribution of the different oscillators to remodel the daily activity pattern remains largely unknown. Our data in Drosophila indicate that light readjusts the interactions between oscillators through two different modes. We show that a morning s-LNv > DN1p circuit works in series, whereas two parallel evening circuits are contributed by LNds and other DN1ps. Based on the photic context, the master pacemaker in the s-LNv neurons swaps its enslaved partner-oscillator-LNd in the presence of light or DN1p in the absence of light-to always link up with the most influential phase-determining oscillator. When exposure to light further increases, the light-activated LNd pacemaker becomes independent by decoupling from the s-LNvs. The calibration of coupling by light is layered on a clock-independent network interaction wherein light upregulates the expression of the PDF neuropeptide in the s-LNvs, which inhibits the behavioral output of the DN1p evening oscillator. Thus, light modifies inter-oscillator coupling and clock-independent output-gating to achieve flexibility in the network. It is likely that the light-induced changes in the Drosophila brain circadian network could reveal general principles of adapting to varying environmental cues in any neuronal multi-oscillator system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cortical Dynamics in Presence of Assemblies of Densely Connected Weight-Hub Neurons

PubMed Central

Setareh, Hesam; Deger, Moritz; Petersen, Carl C. H.; Gerstner, Wulfram

2017-01-01

Experimental measurements of pairwise connection probability of pyramidal neurons together with the distribution of synaptic weights have been used to construct randomly connected model networks. However, several experimental studies suggest that both wiring and synaptic weight structure between neurons show statistics that differ from random networks. Here we study a network containing a subset of neurons which we call weight-hub neurons, that are characterized by strong inward synapses. We propose a connectivity structure for excitatory neurons that contain assemblies of densely connected weight-hub neurons, while the pairwise connection probability and synaptic weight distribution remain consistent with experimental data. Simulations of such a network with generalized integrate-and-fire neurons display regular and irregular slow oscillations akin to experimentally observed up/down state transitions in the activity of cortical neurons with a broad distribution of pairwise spike correlations. Moreover, stimulation of a model network in the presence or absence of assembly structure exhibits responses similar to light-evoked responses of cortical layers in optogenetically modified animals. We conclude that a high connection probability into and within assemblies of excitatory weight-hub neurons, as it likely is present in some but not all cortical layers, changes the dynamics of a layer of cortical microcircuitry significantly. PMID:28690508

Numerical modelling of transient heat and moisture transport in protective clothing

NASA Astrophysics Data System (ADS)

Łapka, P.; Furmański, P.; Wisniewski, T. S.

2016-01-01

The paper presents a complex model of heat and mass transfer in a multi-layer protective clothing exposed to a flash fire and interacting with the human skin. The clothing was made of porous fabric layers separated by air gaps. The fabrics contained bound water in the fibres and moist air in the pores. The moist air was also present in the gaps between fabric layers or internal fabric layer and the skin. Three skin sublayers were considered. The model accounted for coupled heat transfer by conduction, thermal radiation and associated with diffusion of water vapour in the clothing layers and air gaps. Heat exchange due to phase transition of the bound water were also included in the model. Complex thermal and mass transfer conditions at internal or external boundaries between fabric layers and air gaps as well as air gap and skin were assumed. Special attention was paid to modelling of thermal radiation which was coming from the fire, penetrated through protective clothing and absorbed by the skin. For the first time non-grey properties as well as optical phenomena at internal or external boundaries between fabric layers and air gaps as well as air gap and skin were accounted for. A series of numerical simulations were carried out and the risk of heat injures was estimated.

Potential of Aerostats for the Recovery of Disabled Main Battle Tanks and Other Heavy Military Vehicles and Equipment

DTIC Science & Technology

2007-08-01

designs and operates numerous passenger airships. The envelope structure consists of a laminated fabric envelope. This envelope is a large bag...Layered Aerostat Fabric This multi-layered laminate is designed to withstand the sun’s UV rays, acid rain and other environmental concerns. It is...a tough laminate , which inhibits gas loss while providing a high strength-to-weight ratio. The CL75 envelope used a laminate material woven with

Studies on the performance of TiO{sub 2} thin films as protective layer to chlorophyll in Ocimum tenuiflorum L from UV radiation

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

Malliga, P.; Selvi, B. Karunai; Pandiarajan, J.

Thin films of TiO{sub 2} were prepared on glass substrates using sol-gel dip coating technique. The films with 10 coatings were prepared and annealed at temperatures 350°C, 450°C and 550°C for 1 hour in muffle furnace. The annealed films were characterized by X – Ray diffraction (XRD), UV – Visible, AFM, Field Effect Scanning Electron Microscopy (FESEM) and EDAX studies. Chlorophyll has many health benefits due to its structural similarity to human blood and its good chelating ability. It has antimutagenic and anticarcinogenic properties. UV light impairs photosynthesis and reduces size, productivity, and quality in many of the crop plantmore » species. Increased exposure of UV light reduces chlorophyll contents a, b and total content in plants. Titanium Dioxide (TiO{sub 2}) is a wide band gap semiconductor and efficient light harvester. TiO{sub 2} has strong UltraViolet (UV) light absorbing capability. Here, we have studied the performance of TiO{sub 2} thin films as a protective layer to the chlorophyll contents present in medicinal plant, tulsi (Ocimum tenuiflorum L) from UV radiation. The study reveals that crystallite size increases, transmittance decreases and chlorophyll contents increases with increase in annealing temperature. This study showed that TiO{sub 2} thin films are good absorber of UV light and protect the chlorophyll contents a, b and total content in medicinal plants.« less

Liquid crystal displays with plastic substrates

NASA Astrophysics Data System (ADS)

Lueder, Ernst H.

1998-04-01

Plastic substrates for the cells of displays exhibit only 1/6 of the weight of glass substrates; they are virtually unbreakable; their flexibility allows the designer to give them a shape suppressing reflections, to realize a display board on a curved surface or meeting the requirements for an appealing styling; displays with plastics are thinner which provides a wider viewing angle. These features render them attractive for displays in portable systems such as mobile phones, pagers, smart cards, personal digital assistants (PDAs) and portable computers. Reflective displays are especially attractive as they don't need a back light. The most important requirements are the protection of plastics against gas permeation and chemical agents, the prevention of layers on plastics to crack or peel off when the plastic is bent and the development of low temperature thin film processes because the plastics, as a rule, only tolerate temperatures below 150 degrees Celsius. Bistable reflective FLC- and PSCT-displays with plastic substrates will be introduced. Special sputtered SiO2-orientation layers preserve the displayed information even if pressure or torsion is applied. MIM-addressed PDLC-displays require additional Al- or Ti-layers which provide the necessary ductility. Sputtered or PECVD-generated TFTs can be fabricated on plastics at temperatures below 150 degrees Celsius.

Metallic coatings on silicon substrates, and methods of forming metallic coatings on silicon substrates

DOEpatents

Branagan, Daniel J [Idaho Falls, ID; Hyde, Timothy A [Idaho Falls, ID; Fincke, James R [Los Alamos, NM

2008-03-11

The invention includes methods of forming a metallic coating on a substrate which contains silicon. A metallic glass layer is formed over a silicon surface of the substrate. The invention includes methods of protecting a silicon substrate. The substrate is provided within a deposition chamber along with a deposition target. Material from the deposition target is deposited over at least a portion of the silicon substrate to form a protective layer or structure which contains metallic glass. The metallic glass comprises iron and one or more of B, Si, P and C. The invention includes structures which have a substrate containing silicon and a metallic layer over the substrate. The metallic layer contains less than or equal to about 2 weight % carbon and has a hardness of at least 9.2 GPa. The metallic layer can have an amorphous microstructure or can be devitrified to have a nanocrystalline microstructure.

Evaluation of novel disposable, light-weight radiation protection devices in an interventional radiology setting: a randomized controlled trial.

PubMed

Uthoff, Heiko; Peña, Constantino; West, James; Contreras, Francisco; Benenati, James F; Katzen, Barry T

2013-04-01

Radiation exposure to interventionalists is increasing. The currently available standard radiation protection devices are heavy and do not protect the head of the operator. The aim of this study was to evaluate the effectiveness and comfort of caps and thyroid collars made of a disposable, light-weight, lead-free material (XPF) for occupational radiation protection in a clinical setting. Up to two interventional operators were randomized to wear a XPF or standard 0.5-mm lead-equivalent thyroid collars in 60 consecutive endovascular procedures requiring fluoroscopy. Simultaneously a XPF cap was worn by all operators. Radiation doses were measured using dosimeters placed outside and underneath the caps and thyroid collars. Wearing comfort was assessed at the end of each procedure on a visual analog scale (0-100 [100 = optimal]). Patient and procedure data did not differ between the XPF and standard protection groups. The cumulative radiation dose measured outside the cap was 15,700 μSv and outside the thyroid collars 21,240 μSv. Measured radiation attenuation provided by the XPF caps (n = 70), XPF thyroid collars (n = 40), and standard thyroid collars (n = 38) was 85.4% ± 25.6%, 79.7% ± 25.8% and 71.9% ± 34.2%, respectively (mean difference XPF vs standard thyroid collars, 7.8% [95% CI, -5.9% to 21.6%]; p = 0.258). The median XPF cap weight was 144 g (interquartile range, 128-170 g), and the XPF thyroid collars were 27% lighter than the standard thyroid collars (p < 0.0001). Operators rated the comfort of all devices as high (mean scores for XPF caps and XPF thyroid collars 83.4 ± 12.7 (SD) and 88.5 ± 14.6, respectively; mean scores for standard thyroid collars 89.6 ± 9.9) (p = 0.648). Light-weight disposable caps and thyroid collars made of XPF were assessed as being comfortable to wear, and they provide radiation protection similar to that of standard 0.5-mm lead-equivalent thyroid collars.

ICP-MS based methods to characterize nanoparticles of TiO2 and ZnO in sunscreens with focus on regulatory and safety issues.

PubMed

Bocca, Beatrice; Caimi, Stefano; Senofonte, Oreste; Alimonti, Alessandro; Petrucci, Francesco

2018-07-15

This study sought to develop analytical methods to characterize titanium dioxide (TiO 2 ) and zinc oxide (ZnO) nanoparticles (NPs), including the particle size distribution and concentration, in cream and spray sunscreens with different sun protection factor (SPF). The Single Particle Inductively Coupled Plasma-Mass Spectrometry (SP ICP-MS) was used as screening and fast method to determine particles size and number. The Asymmetric Flow-Field Flow Fractionation (AF4-FFF) as a pre-separation technique was on-line coupled to the Multi-Angle Light Scattering (MALS) and ICP-MS to determine particle size distributions and size dependent multi-elemental concentration. Both methods were optimized in sunscreens in terms of recovery, repeatability, limit of detection and linear dynamic range. Results showed that sunscreens contained TiO 2 particles with an average size of ≤107 nm and also a minor number of ZnO particles sized ≤98 nm. The higher fraction of particles <100 nm was observed in sunscreens with SPF 50+ (ca. 80%); the lower percentage (12-35%) in sunscreens with lower SPF values. Also the higher TiO 2 (up to 24% weight) and ZnO (ca. 0.25% weight) concentrations were found in formulations of SPF 50+. Creamy sunscreens could be considered safe containing TiO 2 and ZnO NPs less than the maximum allowable concentration of 25% weight as set by the European legislation. On the contrary, spray products required additional considerations with regard to the potential inhalation of NPs. The developed methods can contribute to the actual demand for regulatory control and safety assessment of metallic NPs in consumers' products. Copyright © 2018 Elsevier B.V. All rights reserved.

Investigation of depth-of-interaction (DOI) effects in single- and dual-layer block detectors by the use of light sharing in scintillators.

PubMed

Yamamoto, Seiichi

2012-01-01

In block detectors for PET scanners that use different lengths of slits in scintillators to share light among photomultiplier tubes (PMTs), a position histogram is distorted when the depth of interaction (DOI) of the gamma photons is near the PMTs (DOI effect). However, it remains unclear whether a DOI effect is observed for block detectors that use light sharing in scintillators. To investigate the effect, I tested the effect for single- and dual-layer block detectors. In the single-layer block detector, Ce doped Gd₂SiO₅ (GSO) crystals of 1.9 × 1.9 × 15 mm³ (0.5 mol% Ce) were used. In the dual-layer block detector, GSO crystals of a 1.9 × 1.9 × 6 mm³ (1.5 mol% Ce) were used for the front layer and GSO crystals of 1.9 × 1.9 × 9 mm³ (0.5 mol% Ce) for the back layer. These scintillators were arranged to form an 8 × 8 matrix with multi-layer optical film inserted partly between the scintillators for obtaining an optimized position response with use of two dual-PMTs. Position histograms and energy responses were measured for these block detectors at three different DOI positions, and the flood histograms were obtained. The results indicated that DOI effects are observed in both block detectors, but the dual-layer block showed more severe distortion in the position histogram as well as larger energy variations. We conclude that, in the block detectors that use light sharing in the scintillators, the DOI effect is an important factor for the performance of the detectors, especially for DOI block detectors.

Photobiology eye safety for horticultural LED lighting: Transmittance performance of eyewear protection using high-irradiant monochromatic LEDs.

PubMed

Wu, Bo-Sen; Lefsrud, Mark G

2018-02-01

Light emitting diodes have slowly gained market share as horticultural lighting systems in greenhouses due to their rapid improvement in color performances and light outputs. These advancements have increased the availability of the full spectrum of visible wavelengths and the corresponding irradiance outputs available to plants. However, light emitting diodes owners have limited information on the proper options for personal eyewear protection as the irradiance levels have increased. The objective of this study was to measure the light transmittance performance of 12 eyewear protection including welding goggles, safety goggles, polarized glasses, and sunglasses across the human visible spectrum (380-740 nm) up to an irradiance level of 1500 W·m -2 from high-irradiant light emitting diodes assemblies. Based on the spectral measurements, certain transmitted spectra exhibited spectrum shifts or an alteration in the bimodal distribution which were different than the light emitting diodes spectra, due to the uneven transmittance efficiencies of the glasses. As for the measured transmittance percentages in two experiments, each type of eyewear protection showed distinct transmittance performances, and the performance of the tested eyewear protection was not impacted by irradiance but was dependent on the wavelength. The mean light transmittance was 1.77% for the welding glasses, 13.12% for the polarized glasses, 15.27% for the safety goggles, and 27.65% for the sunglasses. According to these measured results and the spectral weighting exposure limits from the International Electrotechnical Commission 62471 and EU directive 2006/25, consumers and workers using horticultural lighting can select welding goggles or polarized glasses, to limit the possible ocular impact of the high irradiance of monochromatic light in electrical lighting environment. Sunglasses and safety goggles would not be advised as protection, especially if infrared radiation was used.

Investigation of Large Scale Cortical Models on Clustered Multi-Core Processors

DTIC Science & Technology

2013-02-01

with the bias node ( gray ) denoted as ww and the weights associated with the remaining first layer nodes (black) denoted as W. In forming the overall...Implementation of RBF network on GPU Platform 3.5.1 The Cholesky decomposition algorithm We need to invert the matrix multiplication GTG to

Progressive multi-atlas label fusion by dictionary evolution.

PubMed

Song, Yantao; Wu, Guorong; Bahrami, Khosro; Sun, Quansen; Shen, Dinggang

2017-02-01

Accurate segmentation of anatomical structures in medical images is important in recent imaging based studies. In the past years, multi-atlas patch-based label fusion methods have achieved a great success in medical image segmentation. In these methods, the appearance of each input image patch is first represented by an atlas patch dictionary (in the image domain), and then the latent label of the input image patch is predicted by applying the estimated representation coefficients to the corresponding anatomical labels of the atlas patches in the atlas label dictionary (in the label domain). However, due to the generally large gap between the patch appearance in the image domain and the patch structure in the label domain, the estimated (patch) representation coefficients from the image domain may not be optimal for the final label fusion, thus reducing the labeling accuracy. To address this issue, we propose a novel label fusion framework to seek for the suitable label fusion weights by progressively constructing a dynamic dictionary in a layer-by-layer manner, where the intermediate dictionaries act as a sequence of guidance to steer the transition of (patch) representation coefficients from the image domain to the label domain. Our proposed multi-layer label fusion framework is flexible enough to be applied to the existing labeling methods for improving their label fusion performance, i.e., by extending their single-layer static dictionary to the multi-layer dynamic dictionary. The experimental results show that our proposed progressive label fusion method achieves more accurate hippocampal segmentation results for the ADNI dataset, compared to the counterpart methods using only the single-layer static dictionary. Copyright © 2016 Elsevier B.V. All rights reserved.

A Weighted Deep Representation Learning Model for Imbalanced Fault Diagnosis in Cyber-Physical Systems.

PubMed

Wu, Zhenyu; Guo, Yang; Lin, Wenfang; Yu, Shuyang; Ji, Yang

2018-04-05

Predictive maintenance plays an important role in modern Cyber-Physical Systems (CPSs) and data-driven methods have been a worthwhile direction for Prognostics Health Management (PHM). However, two main challenges have significant influences on the traditional fault diagnostic models: one is that extracting hand-crafted features from multi-dimensional sensors with internal dependencies depends too much on expertise knowledge; the other is that imbalance pervasively exists among faulty and normal samples. As deep learning models have proved to be good methods for automatic feature extraction, the objective of this paper is to study an optimized deep learning model for imbalanced fault diagnosis for CPSs. Thus, this paper proposes a weighted Long Recurrent Convolutional LSTM model with sampling policy (wLRCL-D) to deal with these challenges. The model consists of 2-layer CNNs, 2-layer inner LSTMs and 2-Layer outer LSTMs, with under-sampling policy and weighted cost-sensitive loss function. Experiments are conducted on PHM 2015 challenge datasets, and the results show that wLRCL-D outperforms other baseline methods.

A Weighted Deep Representation Learning Model for Imbalanced Fault Diagnosis in Cyber-Physical Systems

PubMed Central

Guo, Yang; Lin, Wenfang; Yu, Shuyang; Ji, Yang

2018-01-01

Predictive maintenance plays an important role in modern Cyber-Physical Systems (CPSs) and data-driven methods have been a worthwhile direction for Prognostics Health Management (PHM). However, two main challenges have significant influences on the traditional fault diagnostic models: one is that extracting hand-crafted features from multi-dimensional sensors with internal dependencies depends too much on expertise knowledge; the other is that imbalance pervasively exists among faulty and normal samples. As deep learning models have proved to be good methods for automatic feature extraction, the objective of this paper is to study an optimized deep learning model for imbalanced fault diagnosis for CPSs. Thus, this paper proposes a weighted Long Recurrent Convolutional LSTM model with sampling policy (wLRCL-D) to deal with these challenges. The model consists of 2-layer CNNs, 2-layer inner LSTMs and 2-Layer outer LSTMs, with under-sampling policy and weighted cost-sensitive loss function. Experiments are conducted on PHM 2015 challenge datasets, and the results show that wLRCL-D outperforms other baseline methods. PMID:29621131

Stabilized CdSe-CoPi composite photoanode for light-assisted water oxidation by transformation of a CdSe/cobalt metal thin film.

PubMed

Costi, Ronny; Young, Elizabeth R; Bulović, Vladimir; Nocera, Daniel G

2013-04-10

Integration of water splitting catalysts with visible-light-absorbing semiconductors would enable direct solar-energy-to-fuel conversion schemes such as those based on water splitting. A disadvantage of some common semiconductors that possess desirable optical bandgaps is their chemical instability under the conditions needed for oxygen evolution reaction (OER). In this study, we demonstrate the dual benefits gained from using a cobalt metal thin-film as the precursor for the preparation of cobalt-phosphate (CoPi) OER catalyst on cadmium chalcogenide photoanodes. The cobalt layer protects the underlying semiconductor from oxidation and degradation while forming the catalyst and simultaneously facilitates the advantageous incorporation of the cadmium chalcogenide layer into the CoPi layer during continued processing of the electrode. The resulting hybrid material forms a stable photoactive anode for light-assisted water splitting.

Thermal Performance of Aircraft Polyurethane Seat Cushions

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.

1982-01-01

Aircraft seat materials were evaluated in terms of their thermal performance. The materials were evaluated using (a) thermogravimetric analysis, (b) differential scanning calorimetry, (c) a modified NBS smoke chamber to determine the rate of mass loss and (d) the NASA T-3 apparatus to determine the thermal efficiency. In this paper, the modified NBS smoke chamber will be described in detail since it provided the most conclusive results. The NBS smoke chamber was modified to measure the weight loss of material when exposed to a radiant heat source over the range of 2.5 to 7.5 W/sq cm. This chamber has been utilized to evaluate the thermal performance of various heat blocking layers utilized to protect the polyurethane cushioning foam used in aircraft seats. Various kinds of heat blocking layers were evaluated by monitoring the weight loss of miniature seat cushions when exposed to the radiant heat. The effectiveness of aluminized heat blocking systems was demonstrated when compared to conventional heat blocking layers such as neoprene. All heat blocking systems showed good fire protection capabilities when compared to the state-of-the-art, i.e., wool-nylon over polyurethane foam.

Enviropod handbook: A guide to preparation and use of the Environmental Protection Agency's light-weight aerial camera system. [Weber River, Utah

NASA Technical Reports Server (NTRS)

Brower, S. J.; Ridd, M. K.

1984-01-01

The use of the Environmental Protection Agency (EPA) Enviropod camera system is detailed in this handbook which contains a step-by-step guide for mission planning, flights, film processing, indexing, and documentation. Information regarding Enviropod equipment and specifications is included.

Design of p-type cladding layers for tunnel-injected UV-A light emitting diodes

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

Zhang, Yuewei; Krishnamoorthy, Sriram; Akyol, Fatih

Here, we discuss the engineering of p-AlGaN cladding layers for achieving efficient tunnel-injected III-Nitride ultraviolet light emitting diodes (UV LEDs) in the UV-A spectral range. We show that the capacitance-voltage measurements can be used to estimate the compensation and doping in the p-AlGaN layers located between the multi-quantum well region and the tunnel junction layer. By increasing the p-type doping concentration to overcome the background compensation, on-wafer external quantum efficiency and wall-plug efficiency of 3.37% and 1.62%, respectively, were achieved for the tunnel-injected UV LEDs emitting at 325 nm. We also show that interband tunneling hole injection can be usedmore » to realize UV LEDs without any acceptor doping. The work discussed here provides new understanding of hole doping and transport in AlGaN-based UV LEDs and demonstrates the excellent performance of tunnel-injected LEDs for the UV-A wavelength range.« less

Design of p-type cladding layers for tunnel-injected UV-A light emitting diodes

DOE PAGES

Zhang, Yuewei; Krishnamoorthy, Sriram; Akyol, Fatih; ...

2016-11-09

Here, we discuss the engineering of p-AlGaN cladding layers for achieving efficient tunnel-injected III-Nitride ultraviolet light emitting diodes (UV LEDs) in the UV-A spectral range. We show that the capacitance-voltage measurements can be used to estimate the compensation and doping in the p-AlGaN layers located between the multi-quantum well region and the tunnel junction layer. By increasing the p-type doping concentration to overcome the background compensation, on-wafer external quantum efficiency and wall-plug efficiency of 3.37% and 1.62%, respectively, were achieved for the tunnel-injected UV LEDs emitting at 325 nm. We also show that interband tunneling hole injection can be usedmore » to realize UV LEDs without any acceptor doping. The work discussed here provides new understanding of hole doping and transport in AlGaN-based UV LEDs and demonstrates the excellent performance of tunnel-injected LEDs for the UV-A wavelength range.« less

Abiotic tooth enamel

NASA Astrophysics Data System (ADS)

Yeom, Bongjun; Sain, Trisha; Lacevic, Naida; Bukharina, Daria; Cha, Sang-Ho; Waas, Anthony M.; Arruda, Ellen M.; Kotov, Nicholas A.

2017-03-01

Tooth enamel comprises parallel microscale and nanoscale ceramic columns or prisms interlaced with a soft protein matrix. This structural motif is unusually consistent across all species from all geological eras. Such invariability—especially when juxtaposed with the diversity of other tissues—suggests the existence of a functional basis. Here we performed ex vivo replication of enamel-inspired columnar nanocomposites by sequential growth of zinc oxide nanowire carpets followed by layer-by-layer deposition of a polymeric matrix around these. We show that the mechanical properties of these nanocomposites, including hardness, are comparable to those of enamel despite the nanocomposites having a smaller hard-phase content. Our abiotic enamels have viscoelastic figures of merit (VFOM) and weight-adjusted VFOM that are similar to, or higher than, those of natural tooth enamels—we achieve values that exceed the traditional materials limits of 0.6 and 0.8, respectively. VFOM values describe resistance to vibrational damage, and our columnar composites demonstrate that light-weight materials of unusually high resistance to structural damage from shocks, environmental vibrations and oscillatory stress can be made using biomimetic design. The previously inaccessible combinations of high stiffness, damping and light weight that we achieve in these layer-by-layer composites are attributed to efficient energy dissipation in the interfacial portion of the organic phase. The in vivo contribution of this interfacial portion to macroscale deformations along the tooth’s normal is maximized when the architecture is columnar, suggesting an evolutionary advantage of the columnar motif in the enamel of living species. We expect our findings to apply to all columnar composites and to lead to the development of high-performance load-bearing materials.

Flexible Foam Protection Materials for Portable Life Support System Packaging Study

NASA Technical Reports Server (NTRS)

Tang,Henry H.; Dillon, Paul A.; Thomas, Gretchen A.

2009-01-01

This paper discusses the phase I effort in evaluating and selecting a light weight impact protection material for the Constellation Space Suit Element (CSSE) Portable Life Support System (PLSS) conceptual packaging study. A light weight material capable of holding and protecting the components inside the PLSS is required to demonstrate the viability of the flexible PLSS packaging concept. The material needs to distribute, dissipate, and absorb the impact energy of the PLSS falling on the lunar surface. It must also be robust to consistently perform over several Extravehicular Activity (EVA) missions in the extreme lunar thermal vacuum environment. This paper documents the performance requirements for selecting a foam protection material, and the methodologies for evaluating some commercial off-the-shelf (COTS) foam material candidates. It also presents the mechanical properties and impact drop tests results of the foam material candidates. The results of this study suggest that a foam based flexible protection system is a viable solution for PLSS packaging. However, additional works are needed to optimize COTS foam or to develop a composite foam system that will meet all the performance requirements for the CSSE PLSS flexible packaging.

Mechanism of Corrosion by Naphthenic Acids and Organosulfur Compounds at High Temperatures

NASA Astrophysics Data System (ADS)

Jin, Peng

Due to the law of supply and demand, the last decade has witnessed a skyrocketing in the price of light sweet crude oil. Therefore, refineries are increasingly interested in "opportunity crudes", characterized by their discounted price and relative ease of procurement. However, the attractive economics of opportunity crudes come with the disadvantage of high acid/organosulfur compound content, which could lead to corrosion and even failure of facilities in refineries. However, it is generally accepted that organosulfur compounds may form protective iron sulfide layers on the metal surface and decrease the corrosion rate. Therefore, it is necessary to investigate the corrosive property of crudes at high temperatures, the mechanism of corrosion by acids (naphthenic acids) in the presence of organosulfur compounds, and methods to mitigate its corrosive effect. In 2004, an industrial project was initiated at the Institute for Corrosion and Multiphase Technology to investigate the corrosion by naphthenic acids and organosulfur compounds. In this project, for each experiment there were two experimentation phases: pretreatment and challenge. In the first pretreatment phase, a stirred autoclave was filled with a real crude oil fraction or model oil of different acidity and organosulfur compound concentration. Then, the stirred autoclave was heated to high temperatures to examine the corrosivity of the oil to different materials (specimens made from CS and 5% Cr containing steel were used). During the pretreatment, corrosion product layers were formed on the metal surface. In the second challenge phase, the steel specimens pretreated in the first phase were inserted into a rotating cylinder autoclave, called High Velocity Rig (HVR). The HVR was fed with a high-temperature oil solution of naphthenic acids to attack the iron sulfide layers. Based on the difference of specimen weight loss between the two steps, the net corrosion rate could be calculated and the protectiveness of corrosion product layer against naphthenic acid corrosion could be assessed. Routinely, the layers generated in pretreatment and challenge phases were investigated with SEM/EDS (Scanning Electron Microscopy/Energy Dispersive Spectroscopy). Selectively, some thin layers formed in the first or second phase were analyzed with FIB-TEM (Focused Ion Beam - Transmission Electron Microscopy). FIB-TEM analysis revealed that there was an iron oxide layer beneath the iron sulfide layer. Experimental results showed that the iron oxide layer was closely related to the layer protectiveness against naphthenic acid corrosion and its formation was due to the presence of naphthenic acids in the fluid. Finally, a new mechanism of naphthenic acid/organosulfur compound corrosion was proposed based on properties of crudes, results of corrosion experimentation, and microscopic analysis of developed surface layers.

InGaN/GaN multilayer quantum dots yellow-green light-emitting diode with optimized GaN barriers.

PubMed

Lv, Wenbin; Wang, Lai; Wang, Jiaxing; Hao, Zhibiao; Luo, Yi

2012-11-07

InGaN/GaN multilayer quantum dot (QD) structure is a potential type of active regions for yellow-green light-emitting diodes (LEDs). The surface morphologies and crystalline quality of GaN barriers are critical to the uniformity of InGaN QD layers. While GaN barriers were grown in multi-QD layers, we used improved growth parameters by increasing the growth temperature and switching the carrier gas from N2 to H2 in the metal organic vapor phase epitaxy. As a result, a 10-layer InGaN/GaN QD LED is demonstrated successfully. The transmission electron microscopy image shows the uniform multilayer InGaN QDs clearly. As the injection current increases from 5 to 50 mA, the electroluminescence peak wavelength shifts from 574 to 537 nm.

InGaN/GaN multilayer quantum dots yellow-green light-emitting diode with optimized GaN barriers

PubMed Central

2012-01-01

InGaN/GaN multilayer quantum dot (QD) structure is a potential type of active regions for yellow-green light-emitting diodes (LEDs). The surface morphologies and crystalline quality of GaN barriers are critical to the uniformity of InGaN QD layers. While GaN barriers were grown in multi-QD layers, we used improved growth parameters by increasing the growth temperature and switching the carrier gas from N2 to H2 in the metal organic vapor phase epitaxy. As a result, a 10-layer InGaN/GaN QD LED is demonstrated successfully. The transmission electron microscopy image shows the uniform multilayer InGaN QDs clearly. As the injection current increases from 5 to 50 mA, the electroluminescence peak wavelength shifts from 574 to 537 nm. PMID:23134721

An ANN-Based Smart Tomographic Reconstructor in a Dynamic Environment

PubMed Central

de Cos Juez, Francisco J.; Lasheras, Fernando Sánchez; Roqueñí, Nieves; Osborn, James

2012-01-01

In astronomy, the light emitted by an object travels through the vacuum of space and then the turbulent atmosphere before arriving at a ground based telescope. By passing through the atmosphere a series of turbulent layers modify the light's wave-front in such a way that Adaptive Optics reconstruction techniques are needed to improve the image quality. A novel reconstruction technique based in Artificial Neural Networks (ANN) is proposed. The network is designed to use the local tilts of the wave-front measured by a Shack Hartmann Wave-front Sensor (SHWFS) as inputs and estimate the turbulence in terms of Zernike coefficients. The ANN used is a Multi-Layer Perceptron (MLP) trained with simulated data with one turbulent layer changing in altitude. The reconstructor was tested using three different atmospheric profiles and compared with two existing reconstruction techniques: Least Squares type Matrix Vector Multiplication (LS) and Learn and Apply (L + A). PMID:23012524

Infrared and visible image fusion based on visual saliency map and weighted least square optimization

NASA Astrophysics Data System (ADS)

Ma, Jinlei; Zhou, Zhiqiang; Wang, Bo; Zong, Hua

2017-05-01

The goal of infrared (IR) and visible image fusion is to produce a more informative image for human observation or some other computer vision tasks. In this paper, we propose a novel multi-scale fusion method based on visual saliency map (VSM) and weighted least square (WLS) optimization, aiming to overcome some common deficiencies of conventional methods. Firstly, we introduce a multi-scale decomposition (MSD) using the rolling guidance filter (RGF) and Gaussian filter to decompose input images into base and detail layers. Compared with conventional MSDs, this MSD can achieve the unique property of preserving the information of specific scales and reducing halos near edges. Secondly, we argue that the base layers obtained by most MSDs would contain a certain amount of residual low-frequency information, which is important for controlling the contrast and overall visual appearance of the fused image, and the conventional "averaging" fusion scheme is unable to achieve desired effects. To address this problem, an improved VSM-based technique is proposed to fuse the base layers. Lastly, a novel WLS optimization scheme is proposed to fuse the detail layers. This optimization aims to transfer more visual details and less irrelevant IR details or noise into the fused image. As a result, the fused image details would appear more naturally and be suitable for human visual perception. Experimental results demonstrate that our method can achieve a superior performance compared with other fusion methods in both subjective and objective assessments.

Sensing human physiological response using wearable carbon nanotube-based fabrics

NASA Astrophysics Data System (ADS)

Wang, Long; Loh, Kenneth J.; Koo, Helen S.

2016-04-01

Flexible and wearable sensors for human monitoring have received increased attention. Besides detecting motion and physical activity, measuring human vital signals (e.g., respiration rate and body temperature) provide rich data for assessing subjects' physiological or psychological condition. Instead of using conventional, bulky, sensing transducers, the objective of this study was to design and test a wearable, fabric-like sensing system. In particular, multi-walled carbon nanotube (MWCNT)-latex thin films of different MWCNT concentrations were first fabricated using spray coating. Freestanding MWCNT-latex films were then sandwiched between two layers of flexible fabric using iron-on adhesive to form the wearable sensor. Second, to characterize its strain sensing properties, the fabric sensors were subjected to uniaxial and cyclic tensile load tests, and they exhibited relatively stable electromechanical responses. Finally, the wearable sensors were placed on a human subject for monitoring simple motions and for validating their practical strain sensing performance. Overall, the wearable fabric sensor design exhibited advances such as flexibility, ease of fabrication, light weight, low cost, noninvasiveness, and user comfort.

Effects of white-tailed deer and invasive plants on the herb layer of suburban forests.

PubMed

Morrison, Janet A

2017-11-01

Lack of hunting and predators and proximity to human communities make suburban forests prone to high deer abundance and non-native plant invasions. I investigated these likely drivers of community structure in the herb layers of six suburban forests in one region of New Jersey, USA. In 223 plots I assessed the herb layer response to 2.5 years with or without deer fencing and the early stage of invasion from seed additions of Microstegium vimineum , an invasive, annual grass. Non-native plants and herbaceous native plants were affected very little by fencing or M. vimineum invasion. In contrast, across all forests the combination of deer access and M. vimineum addition had a strongly negative effect on woody native percent cover. Forests differed in overall fencing effects on woody natives; their cover was greater in fenced plots in just three forests, suggesting greater deer pressure in those forests during the experiment. The early invasion by M. vimineum was greatest in two of these same forests, but was not influenced by fencing. Multi-group structural equation modelling compared two groups of forests that differed in vegetation abundance and other characteristics. It paralleled the results above and also showed no negative influence of non-native cover on native cover, even in the forests where non-native cover was greater. It identified a positive effect of light level on herb layer plants in the forests with less vegetation, and also revealed a positive effect of soil water potential (SWP) on non-native plants in the forests with more vegetation, which had higher SWP. These suburban forests within a common region varied widely in native and non-native herb layer abundance, the early success of M. vimineum invasion and the herb layer's response to early invasion and protection from deer.

Endolithic microniches support habitability

NASA Astrophysics Data System (ADS)

Gómez, F.; Rodríguez, N.; Rodríguez-Manfredi, J. A.; Fernández-Sampedro, M.; Amils, R.

2013-09-01

Particular micro-niches on extreme environments give us some clues about the habitability potential under protected environments with important connotations from an astrobiological point of view [1]. The salts precipitation patters in extreme environments can contribute to biomineralization processes which could be of special interest for organics but also life preservation on environmental harsh conditions. These "oasys" for organics and/or life forms are of special as trobiological interest and should attract our attention in other planets and we should be looking for it during rover exploration missions. Endolithic micro niches in Rio Tinto salts precipitates determine controlled scenarios where phototrops develop under controlled conditions. Rio Tinto, 100 km river located at South West of Spain, is being taken as a well reported Mars analog due to the similarities in the mineralogy of the system which that reported by MER Opportunity Rover missions which landed in Meridiani Planum where sedimentary deposits have been identified in different craters [2]. Interesting multi layered salty deposits were identified in Rio Tinto source area where endolithic micro niches were settled [3]. Green layers appear included in brown stratified salt precipitates. The crust deposit was between 5 mm and 1 cm width. The layered structure is deposited over rocks or over man made structures as dam or mining tunnels walls but always in places with specific environmental characteristics. It appears in not direct Sun light exposed places (shadow side of walls) with thermal and pH stability.

Multi-viewpoint Image Array Virtual Viewpoint Rapid Generation Algorithm Based on Image Layering

NASA Astrophysics Data System (ADS)

Jiang, Lu; Piao, Yan

2018-04-01

The use of multi-view image array combined with virtual viewpoint generation technology to record 3D scene information in large scenes has become one of the key technologies for the development of integrated imaging. This paper presents a virtual viewpoint rendering method based on image layering algorithm. Firstly, the depth information of reference viewpoint image is quickly obtained. During this process, SAD is chosen as the similarity measure function. Then layer the reference image and calculate the parallax based on the depth information. Through the relative distance between the virtual viewpoint and the reference viewpoint, the image layers are weighted and panned. Finally the virtual viewpoint image is rendered layer by layer according to the distance between the image layers and the viewer. This method avoids the disadvantages of the algorithm DIBR, such as high-precision requirements of depth map and complex mapping operations. Experiments show that, this algorithm can achieve the synthesis of virtual viewpoints in any position within 2×2 viewpoints range, and the rendering speed is also very impressive. The average result proved that this method can get satisfactory image quality. The average SSIM value of the results relative to real viewpoint images can reaches 0.9525, the PSNR value can reaches 38.353 and the image histogram similarity can reaches 93.77%.

Investigation of weldable iron-aluminum alloys for corrosion protection in high temperature oxidizing-sulfidizing environments

NASA Astrophysics Data System (ADS)

Banovic, Stephen William

The objective of the present study was to investigate the corrosion behavior of weldable Fe-Al alloys in environments representative of low NOx gas compositions, i.e., high partial pressures of sulfur [p(S2)] and low partial pressures of oxygen [p(O2)]. Through an integrated experimental approach involving thermogravimetric techniques, post-exposure metallographic examination of the corroded samples, and detailed chemical microanalyses of the reaction scales, the effects of aluminum content, temperature, and gas composition on the corrosion behavior were observed. The corrosion behavior of Fe-Al alloys was found to be directly related to the type and morphology of corrosion product that formed during high temperature exposure in the oxidizing/sulfidizing environment. The inhibition stage was characterized by growth of a thin, gamma alumina scale that suppressed excessive degradation of the substrate at all temperatures. Localized mechanical failure of the initial passive scale, in combination with the inability to re-establish itself, was found to result in nodular growth of non-protective sulfide phases across the sample face due to short circuit diffusion through the gamma alumina layer. With the remnants of the initial gamma scale found between the outer and inner scale, it was concluded that these layers grew by iron diffusion outward and sulfur diffusion inward, respectively. The corrosion rate observed during development of these morphologies was directly related to the density of the nodules on the surface and the exposure temperature. The final period observed was the steady-state stage. This behavior was encountered from the onset of exposure for all Fe-5 wt% Al alloys tested, or upon coalescence of the nodular growths. After initially high corrosion rates, the weight gains were found to increase at a steady rate as subsequent growth occurred via diffusion through the continuous scale. Determination of the corrosion product growth mechanism could not be directly obtained from the thermogravimetric data. For samples with relatively high weight gains, enhanced scale growth at the comers and edges of the sample, as well as the morphology of the multi-layered, multi-phase corrosion products, violated the assumptions necessary for data manipulation by this means. The results from this study indicate that weldable compositions of Fe-Al alloys (10 wt% Al) show excellent corrosion resistance to aggressive low NO x gas compositions in the service temperature range (below 600°C). With the potential promise for applications requiring a combination of weldability and corrosion resistance in moderately reducing environments, these alloys are viable candidates for further evaluation for use as sulfidation resistant weld overlay coatings. (Abstract shortened by UMI.)

Estimation of crosstalk in LED fNIRS by photon propagation Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Iwano, Takayuki; Umeyama, Shinji

2015-12-01

fNIRS (functional near-Infrared spectroscopy) can measure brain activity non-invasively and has advantages such as low cost and portability. While the conventional fNIRS has used laser light, LED light fNIRS is recently becoming common in use. Using LED for fNIRS, equipment can be more inexpensive and more portable. LED light, however, has a wider illumination spectrum than laser light, which may change crosstalk between the calculated concentration change of oxygenated and deoxygenated hemoglobins. The crosstalk is caused by difference in light path length in the head tissues depending on wavelengths used. We conducted Monte Carlo simulations of photon propagation in the tissue layers of head (scalp, skull, CSF, gray matter, and white matter) to estimate the light path length in each layers. Based on the estimated path lengths, the crosstalk in fNIRS using LED light was calculated. Our results showed that LED light more increases the crosstalk than laser light does when certain combinations of wavelengths were adopted. Even in such cases, the crosstalk increased by using LED light can be effectively suppressed by replacing the value of extinction coefficients used in the hemoglobin calculation to their weighted average over illumination spectrum.

Salvaging and Conserving Water Damaged Photographic Materials

NASA Astrophysics Data System (ADS)

Suzuki, Ryuji

Degradation of water damaged photographic materials is discussed; the most vulnerable elements are gelatin layers and silver image. A simple and inexpensive chemical treatment is proposed, consisting of a bath containing a gelatin-protecting biocide and a silver image protecting agent. These ingredients were selected among those used in manufacturing of silver halide photographic emulsions or processing chemicals. Experiments confirmed that this treatment significantly reduced oxidative attacks to silver image and bacterial degradation of gelatin layers. The treated material was also stable under intense light fading test. Method of hardening gelatin to suppress swelling is also discussed.

Gemini-Titan (GT)-8 - Lightweight Suit - MSC

NASA Image and Video Library

1965-12-06

S65-60035 (6 Dec. 1965) --- The new light-weight spacesuit planned for possible use during the Gemini-7 mission is modeled by Fred R. Spross, Gemini Support Office, Crew Systems Division. The spacesuit weighs 16 pounds, including the aviator's crash helmet. The suit is designed so that it may be partially or completely removed during flight. It has two layers of material while the previously used Gemini spacesuit has four layers. Photo credit: NASA

Bessel light sheet structured illumination microscopy

NASA Astrophysics Data System (ADS)

Noshirvani Allahabadi, Golchehr

Biomedical study researchers using animals to model disease and treatment need fast, deep, noninvasive, and inexpensive multi-channel imaging methods. Traditional fluorescence microscopy meets those criteria to an extent. Specifically, two-photon and confocal microscopy, the two most commonly used methods, are limited in penetration depth, cost, resolution, and field of view. In addition, two-photon microscopy has limited ability in multi-channel imaging. Light sheet microscopy, a fast developing 3D fluorescence imaging method, offers attractive advantages over traditional two-photon and confocal microscopy. Light sheet microscopy is much more applicable for in vivo 3D time-lapsed imaging, owing to its selective illumination of tissue layer, superior speed, low light exposure, high penetration depth, and low levels of photobleaching. However, standard light sheet microscopy using Gaussian beam excitation has two main disadvantages: 1) the field of view (FOV) of light sheet microscopy is limited by the depth of focus of the Gaussian beam. 2) Light-sheet images can be degraded by scattering, which limits the penetration of the excitation beam and blurs emission images in deep tissue layers. While two-sided sheet illumination, which doubles the field of view by illuminating the sample from opposite sides, offers a potential solution, the technique adds complexity and cost to the imaging system. We investigate a new technique to address these limitations: Bessel light sheet microscopy in combination with incoherent nonlinear Structured Illumination Microscopy (SIM). Results demonstrate that, at visible wavelengths, Bessel excitation penetrates up to 250 microns deep in the scattering media with single-side illumination. Bessel light sheet microscope achieves confocal level resolution at a lateral resolution of 0.3 micron and an axial resolution of 1 micron. Incoherent nonlinear SIM further reduces the diffused background in Bessel light sheet images, resulting in confocal quality images in thick tissue. The technique was applied to live transgenic zebra fish tg(kdrl:GFP), and the sub-cellular structure of fish vasculature genetically labeled with GFP was captured in 3D. The superior speed of the microscope enables us to acquire signal from 200 layers of a thick sample in 4 minutes. The compact microscope uses exclusively off-the-shelf components and offers a low-cost imaging solution for studying small animal models or tissue samples.

Real-time 3-D X-ray and gamma-ray viewer

NASA Technical Reports Server (NTRS)

Yin, L. I. (Inventor)

1983-01-01

A multi-pinhole aperture lead screen forms an equal plurality of invisible mini-images having dissimilar perspectives of an X-ray and gamma-ray emitting object (ABC) onto a near-earth phosphor layer. This layer provides visible light mini-images directly into a visible light image intensifier. A viewing screen having an equal number of dissimilar perspective apertures distributed across its face in a geometric pattern identical to the lead screen, provides a viewer with a real, pseudoscopic image (A'B'C') of the object with full horizontal and vertical parallax. Alternatively, a third screen identical to viewing screen and spaced apart from a second visible light image intensifier, may be positioned between the first image intensifier and the viewing screen, thereby providing the viewer with a virtual, orthoscopic image (A"B"C") of the object (ABC) with full horizontal and vertical parallax.

Qualification of security printing features

NASA Astrophysics Data System (ADS)

Simske, Steven J.; Aronoff, Jason S.; Arnabat, Jordi

2006-02-01

This paper describes the statistical and hardware processes involved in qualifying two related printing features for their deployment in product (e.g. document and package) security. The first is a multi-colored tiling feature that can also be combined with microtext to provide additional forms of security protection. The color information is authenticated automatically with a variety of handheld, desktop and production scanners. The microtext is authenticated either following magnification or manually by a field inspector. The second security feature can also be tile-based. It involves the use of two inks that provide the same visual color, but differ in their transparency to infrared (IR) wavelengths. One of the inks is effectively transparent to IR wavelengths, allowing emitted IR light to pass through. The other ink is effectively opaque to IR wavelengths. These inks allow the printing of a seemingly uniform, or spot, color over a (truly) uniform IR emitting ink layer. The combination converts a uniform covert ink and a spot color to a variable data region capable of encoding identification sequences with high density. Also, it allows the extension of variable data printing for security to ostensibly static printed regions, affording greater security protection while meeting branding and marketing specifications.

Learning relevant features of data with multi-scale tensor networks

NASA Astrophysics Data System (ADS)

Miles Stoudenmire, E.

2018-07-01

Inspired by coarse-graining approaches used in physics, we show how similar algorithms can be adapted for data. The resulting algorithms are based on layered tree tensor networks and scale linearly with both the dimension of the input and the training set size. Computing most of the layers with an unsupervised algorithm, then optimizing just the top layer for supervised classification of the MNIST and fashion MNIST data sets gives very good results. We also discuss mixing a prior guess for supervised weights together with an unsupervised representation of the data, yielding a smaller number of features nevertheless able to give good performance.

A computational analysis of the ballistic performance of light-weight hybrid composite armors

NASA Astrophysics Data System (ADS)

Grujicic, M.; Pandurangan, B.; Koudela, K. L.; Cheeseman, B. A.

2006-11-01

The ability of hybrid light-weight fiber-reinforced polymer-matrix composite laminate armor to withstand the impact of a fragment simulating projectile (FSP) is investigated using a non-linear dynamics transient computational analysis. The hybrid armor is constructed using various combinations and stacking sequences of a high-strength/high-stiffness carbon fiber-reinforced epoxy (CFRE) and a high-ductility/high-toughness Kevlar fiber-reinforced epoxy (KFRE) composite laminates of different thicknesses. The results obtained indicate that at a fixed thickness of the armor both the stacking sequence and the number of CFRE/KFRE laminates substantially affect the ballistic performance of the armor. Specifically, it is found that the armor consisting of one layer of KFRE and one layer of CFRE, with KFRE laminate constituting the outer surface of the armor, possesses the maximum resistance towards the projectile-induced damage and failure. The results obtained are rationalized using an analysis of the elastic wave reflection and transmission behavior at the inter-laminate and laminate/air interfaces.

Investigation of Corrosion Protection in Oil Mineral Reservoirs by Nanocomposites Used as Coating Layers

NASA Astrophysics Data System (ADS)

Al-Sarraf, Abdulhameed R.; Al-Saaidi, Samer A.

2018-05-01

In this study, a number of nanocomposites were prepared by adding magnesium oxide (MgO) with weight percentages (1, 2 & 3)% to cellulose nitrate and sodium silicate as an intermediate layer and other nanocomposites by adding MgO, coal coke and hybrid (MgO & coal coke with ratio 1:1) with weight percentages (1, 2 & 3)% to epoxy resin as final layer. The identity of the used metal is determined by spectrometer OE thermo. The nature and topography of the surface layers were examined by optical microscope and atomic force microscope (AFM). Mechanical properties are indicated by hardness, wear rate, impact strength and adhesion strength. The efficiency of the layers prepared to inhibit corrosion in the oil mineral reservoirs of the oil products distribution company was studied by electrochemical corrosion test in addition to the chemical corrosion test. The used metal is (St-37) according to (ASTM). It was found that the best intermediate layer (cellulose nitrate+3%MgO) and the final layer is the epoxy resin reinforced by 2% hybrid.

Analysis of multi-channel microscopy: Spectral self-interference, multi-detector confocal and 4Pi systems

NASA Astrophysics Data System (ADS)

Davis, Brynmor J.

Fluorescence microscopy is an important and ubiquitous tool in biological imaging due to the high specificity with which fluorescent molecules can be attached to an organism and the subsequent nondestructive in-vivo imaging allowed. Focused-light microscopies allow three-dimensional fluorescence imaging but their resolution is restricted by diffraction. This effect is particularly limiting in the axial dimension as the diffraction-limited focal volume produced by a lens is more extensive along the optical axis than perpendicular to it. Approaches such as confocal microscopy and 4Pi microscopy have been developed to improve the axial resolution. Spectral Self-Interference Fluorescence Microscopy (SSFM) is another high-axial-resolution technique and is the principal subject of this dissertation. Nanometer-precision localization of a single fluorescent layer has been demonstrated using SSFM. This accuracy compares favorably with the axial resolutions given by confocal and 4Pi systems at similar operating parameters (these resolutions are approximately 350nm and 80nm respectively). This theoretical work analyzes the expected performance of the SSFM system when imaging a general object, i.e. an arbitrary fluorophore density function rather than a single layer. An existing model of SSFM is used in simulations to characterize the system's resolution. Several statistically-based reconstruction methods are applied to show that the expected resolution for SSFM is similar to 4Pi microscopy for a general object but does give very high localization accuracy when the object is known to consist of a limited number of layers. SSFM is then analyzed in a linear systems framework and shown to have strong connections, both physically and mathematically, to a multi-channel 4Pi microscope. Fourier-domain analysis confirms that SSFM cannot be expected to outperform this multi-channel 4Pi instrument. Differences between the channels in spatial-scanning, multi-channel microscopies are then exploited to show that such instruments can operate at a sub-Nyquist scanning rate but still produce images largely free of aliasing effects. Multi-channel analysis is also used to show how light typically discarded in confocal and 4Pi systems can be collected and usefully incorporated into the measured image.

Photoelectrochemical devices for solar water splitting - materials and challenges.

PubMed

Jiang, Chaoran; Moniz, Savio J A; Wang, Aiqin; Zhang, Tao; Tang, Junwang

2017-07-31

It is widely accepted within the community that to achieve a sustainable society with an energy mix primarily based on solar energy we need an efficient strategy to convert and store sunlight into chemical fuels. A photoelectrochemical (PEC) device would therefore play a key role in offering the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The past five years have seen a surge in the development of promising semiconductor materials. In addition, low-cost earth-abundant co-catalysts are ubiquitous in their employment in water splitting cells due to the sluggish kinetics of the oxygen evolution reaction (OER). This review commences with a fundamental understanding of semiconductor properties and charge transfer processes in a PEC device. We then describe various configurations of PEC devices, including single light-absorber cells and multi light-absorber devices (PEC, PV-PEC and PV/electrolyser tandem cell). Recent progress on both photoelectrode materials (light absorbers) and electrocatalysts is summarized, and important factors which dominate photoelectrode performance, including light absorption, charge separation and transport, surface chemical reaction rate and the stability of the photoanode, are discussed. Controlling semiconductor properties is the primary concern in developing materials for solar water splitting. Accordingly, strategies to address the challenges for materials development in this area, such as the adoption of smart architectures, innovative device configuration design, co-catalyst loading, and surface protection layer deposition, are outlined throughout the text, to deliver a highly efficient and stable PEC device for water splitting.

Solar energy panel

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

Hyman, M.

1980-03-04

A light-weight, low-cost and high efficiency solar panel includes a light-weight rectangular wood frame which surrounds and houses a copper absorber plate. A pair of spaced glazings, formed from plastic film materials, are disposed above the absorber to define a pair of enclosed air spaces. The lower glazing is capable of withstanding high temperatures and the upper glazing material is capable of providing good weather resistance. The material of the upper glazing extends fully about the frame to protect the entire frame from weathering. Insulation is provided beneath the absorber plate. The frame rests on top of a bottom sheetmore » of insulative foam plastic which is wrapped in a plastic envelope. The surrounding film of the outer glazing is bonded securely to the envelope to encase the entire panel within a protective sealed envelope of weather-resistant plastic film.« less

Cardiac Arrhythmia Classification by Multi-Layer Perceptron and Convolution Neural Networks.

PubMed

Savalia, Shalin; Emamian, Vahid

2018-05-04

The electrocardiogram (ECG) plays an imperative role in the medical field, as it records heart signal over time and is used to discover numerous cardiovascular diseases. If a documented ECG signal has a certain irregularity in its predefined features, this is called arrhythmia, the types of which include tachycardia, bradycardia, supraventricular arrhythmias, and ventricular, etc. This has encouraged us to do research that consists of distinguishing between several arrhythmias by using deep neural network algorithms such as multi-layer perceptron (MLP) and convolution neural network (CNN). The TensorFlow library that was established by Google for deep learning and machine learning is used in python to acquire the algorithms proposed here. The ECG databases accessible at PhysioBank.com and kaggle.com were used for training, testing, and validation of the MLP and CNN algorithms. The proposed algorithm consists of four hidden layers with weights, biases in MLP, and four-layer convolution neural networks which map ECG samples to the different classes of arrhythmia. The accuracy of the algorithm surpasses the performance of the current algorithms that have been developed by other cardiologists in both sensitivity and precision.

SENSITIVITY ANALYSIS OF THE MULTI-LAYER MODEL USED IN THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET)

EPA Science Inventory

The U.S. Environmental Protection Agency (EPA) established the Clean Air Status and Trends Network (CASTNET) and its predecessor, the National Dry Deposition Network (NDDN), as national air quality and meteorological monitoring networks. The purpose of CASTNET is to track the pr...

Clinical study assessing the photosensitizer accumulation and light penetration for esophageal cancer prior to treatment by PDT

NASA Astrophysics Data System (ADS)

Bargo, Paulo R.; Jacques, Steven L.

2001-07-01

The FDA has approved PDT using Photofrin for certain esophageal and lung cancers, specifying an approved prescription of administered drug (mg/kg body weight) and administered light (J/linear cm of cylindrical fiber). This paper describes our development of a multi-optical fiber catheter for endoscopic use which documents the drug accumulated in the target tissues and the light penetration into the target tissues. The catheter uses reflectance to specify the light penetration depth and uses reflectance- corrected fluorescence to document drug accumulation. The goal is to document the variation in drug and light received by patients who are administered the FDA-approved prescription.

Wear evaluation of a cross-linked medical grade polyethylene by ultra thin layer activation compared to gravimetry

NASA Astrophysics Data System (ADS)

Stroosnijder, Marinus F.; Hoffmann, Michael; Sauvage, Thierry; Blondiaux, Gilbert; Vincent, Laetitia

2005-01-01

Most of today's artificial joints rely on an articulating couple consisting of a CoCrMo alloy and a medical grade polyethylene. The wear of the polyethylene component is the major cause for long-term failure of these prostheses since the wear debris leads to adverse biological reactions. The polyethylene wear is usually measured by gravimetric methods, which are limited due to a low sensitivity and accuracy. To demonstrate the reliability of ultra thin layer activation (UTLA) as an alternative technique, wear tests on a cross-linked ultra-high-molecular weight polyethylene (XLPE) sliding against CoCrMo were performed on a wear tester featuring multi-directional sliding motion. The amount of polyethylene wear was evaluated by both UTLA and gravimetry. The particular TLA method used in this work employed the implantation of 7Be radioactive recoils into the polyethylene surface by means of a light mass particle beam. The results indicate that apart from its relatively high sensitivity, UTLA also offers the possibility for on-line measurements of polyethylene wear. This makes it a viable and complementary technique in wear test studies for medical implant purposes especially for those involving wear resistant materials and for rapid wear screening.

Monte Carlo modeling of time-resolved fluorescence for depth-selective interrogation of layered tissue.

PubMed

Pfefer, T Joshua; Wang, Quanzeng; Drezek, Rebekah A

2011-11-01

Computational approaches for simulation of light-tissue interactions have provided extensive insight into biophotonic procedures for diagnosis and therapy. However, few studies have addressed simulation of time-resolved fluorescence (TRF) in tissue and none have combined Monte Carlo simulations with standard TRF processing algorithms to elucidate approaches for cancer detection in layered biological tissue. In this study, we investigate how illumination-collection parameters (e.g., collection angle and source-detector separation) influence the ability to measure fluorophore lifetime and tissue layer thickness. Decay curves are simulated with a Monte Carlo TRF light propagation model. Multi-exponential iterative deconvolution is used to determine lifetimes and fractional signal contributions. The ability to detect changes in mucosal thickness is optimized by probes that selectively interrogate regions superficial to the mucosal-submucosal boundary. Optimal accuracy in simultaneous determination of lifetimes in both layers is achieved when each layer contributes 40-60% of the signal. These results indicate that depth-selective approaches to TRF have the potential to enhance disease detection in layered biological tissue and that modeling can play an important role in probe design optimization. Published by Elsevier Ireland Ltd.

Linguistic Multi-Attribute Group Decision Making with Risk Preferences and Its Use in Low-Carbon Tourism Destination Selection.

PubMed

Lin, Hui; Wang, Zhou-Jing

2017-09-17

Low-carbon tourism plays an important role in carbon emission reduction and environmental protection. Low-carbon tourism destination selection often involves multiple conflicting and incommensurate attributes or criteria and can be modelled as a multi-attribute decision-making problem. This paper develops a framework to solve multi-attribute group decision-making problems, where attribute evaluation values are provided as linguistic terms and the attribute weight information is incomplete. In order to obtain a group risk preference captured by a linguistic term set with triangular fuzzy semantic information, a nonlinear programming model is established on the basis of individual risk preferences. We first convert individual linguistic-term-based decision matrices to their respective triangular fuzzy decision matrices, which are then aggregated into a group triangular fuzzy decision matrix. Based on this group decision matrix and the incomplete attribute weight information, a linear program is developed to find an optimal attribute weight vector. A detailed procedure is devised for tackling linguistic multi-attribute group decision making problems. A low-carbon tourism destination selection case study is offered to illustrate how to use the developed group decision-making model in practice.

Linguistic Multi-Attribute Group Decision Making with Risk Preferences and Its Use in Low-Carbon Tourism Destination Selection

PubMed Central

Lin, Hui; Wang, Zhou-Jing

2017-01-01

Low-carbon tourism plays an important role in carbon emission reduction and environmental protection. Low-carbon tourism destination selection often involves multiple conflicting and incommensurate attributes or criteria and can be modelled as a multi-attribute decision-making problem. This paper develops a framework to solve multi-attribute group decision-making problems, where attribute evaluation values are provided as linguistic terms and the attribute weight information is incomplete. In order to obtain a group risk preference captured by a linguistic term set with triangular fuzzy semantic information, a nonlinear programming model is established on the basis of individual risk preferences. We first convert individual linguistic-term-based decision matrices to their respective triangular fuzzy decision matrices, which are then aggregated into a group triangular fuzzy decision matrix. Based on this group decision matrix and the incomplete attribute weight information, a linear program is developed to find an optimal attribute weight vector. A detailed procedure is devised for tackling linguistic multi-attribute group decision making problems. A low-carbon tourism destination selection case study is offered to illustrate how to use the developed group decision-making model in practice. PMID:28926985

Zero-internal fields in nonpolar InGaN/GaN multi-quantum wells grown by the multi-buffer layer technique.

PubMed

Song, Hooyoung; Kim, Jin Soak; Kim, Eun Kyu; Seo, Yong Gon; Hwang, Sung-Min

2010-04-02

The potential of nonpolar a-plane InGaN/GaN multi-quantum wells (MQWs), which are free from a strong piezoelectric field, was demonstrated. An a-GaN template grown on an r-plane sapphire substrate by the multi-buffer layer technique showed high structural quality with an omega full width at half maximum value along the c-axis of 418 arcsec obtained from high-resolution x-ray diffraction analysis. From barrier analysis by deep level transient spectroscopy, it appeared that a-plane InGaN/GaN MQWs can solve the efficiency droop problem as they have a lower electron capture barrier than the c-plane sample. The peak shift of the temperature-dependent photoluminescence signal for the nonpolar InGaN/GaN MQWs was well fitted by Varshni's empirical equation with zero-internal fields. A high photoluminescence efficiency of 0.27 from this sample also showed that nonpolar MQWs can be the key factor to solve the efficiency limitation in conventional c-plane GaN based light emitting diodes.

High precision position sensor based on CPA in a composite multi-layered system.

PubMed

Dey, Sanjeeb; Singh, Suneel; Rao, Desai Narayana

2018-04-16

We propose a scheme for high precision position sensing based on coherent perfect absorption (CPA) in a five-layered structure comprising three layers of metal-dielectric composites and two spacer (air) layers. Both the outermost interfaces of the five layered medium are irradiated by two identical coherent light waves at the same angle of incidence. We first investigate the occurrence of CPA in a symmetric layered structure as a function of different system parameters for oblique incidence. Thereafter, by shifting the middle layer, beginning from one end of the structure to the other, we observe the periodic occurrence of extremely narrow CPA resonances at several positions of the middle layer. Moreover this phenomenon is seen to recur even at many other wavelengths. We discuss how the position sensitivity of this phenomenon can be utilized for designing a CPA based high precision position sensing device.

[Effects of stereoscopic cultivation on photosynthetic characteristics and growth of Tulipa edulis].

PubMed

Sun, Yuan; Guo, Qiao-Sheng; Zhu, Zai-Biao; Lin, Jian-Luo; Zhou, Bo-Ya; Zhao, Min-Jie

2016-06-01

The effect of stereoscopic cultivation on the growth, photosynthetic characteristics and yield of Tulipa edulis was studied to explore the feasibility of stereoscopic cultivation on efficient cultivation of T.edulis. Total leaf area and photosynthetic parameters of T.edulis under stereoscopic cultivation (the upper, middle and the lower layers ) and the control were measured using LI-3100 leaf area meter and LI-6400XT photosynthesis system in the growing peak period of T.edulis.Plant biomass and biomass allocation were also determined.In addition, the bulb regeneration and yield of T.edulis were measured in the harvesting time.The results indicated that in the middle layer of stereoscopic cultivation, leaf biomass proportion was the highest, but total bulb fresh and dry weight and output growth (fresh weight) were the lowest among the treatments.And total bulb fresh weight in the middle of stereoscopic cultivation reduced significantly, by 22.84%, compared with the control.Light intensity in the lower layer of stereoscopic cultivation was moderate, in which T.edulis net photosynthetic rate and water use efficiency were higher than those of the other layers of stereoscopic cultivation, and bulb biomass proportion was the highest in all the treatments.No significant difference was detected in the total bulb fresh weight, dry weight and output growth (fresh weight) between the middle layer of stereoscopic cultivation and the control.In general, there was no significant difference in the growth status of T.edulis between stereoscopic cultivation and the control.Stereoscopic cultivation increased the yield of T.edulis by 161.66% in fresh weight and 141.35% in dry weight compared with the control in the condition of the same land area, respectively.In conclusion, stereoscopic cultivation can improve space utilization, increase the production, and achieve the high density cultivation of T.edulis. Copyright© by the Chinese Pharmaceutical Association.

Investigation into Composites Property Effect on the Forming Limits of Multi-Layer Hybrid Sheets Using Hydroforming Technology

NASA Astrophysics Data System (ADS)

Liu, Shichen; Lang, Lihui; Guan, Shiwei; Alexandrov, Seigei; Zeng, Yipan

2018-04-01

Fiber-metal laminates (FMLs) such as Kevlar reinforced aluminum laminate (ARALL), Carbon reinforced aluminum laminate (CARALL), and Glass reinforced aluminum laminate (GLARE) offer great potential for weight reduction applications in automobile and aerospace construction. In order to investigate the feasibility for utilizing such materials in the form of laminates, sheet hydroforming technology are studied under the condition of uniform blank holder force for three-layered aluminum and aluminum-composite laminates using orthogonal carbon and Kevlar as well as glass fiber in the middle. The experimental results validate the finite element results and they exhibited that the forming limit of glass fiber in the middle is the highest among the studied materials, while carbon fiber material performs the worst. Furthermore, the crack modes are different for the three kinds of fiber materials investigated in the research. This study provides fundamental guidance for the selection of multi-layer sheet materials in the future manufacturing field.

Application of the weighted total field-scattering field technique to 3D-PSTD light scattering model

NASA Astrophysics Data System (ADS)

Hu, Shuai; Gao, Taichang; Liu, Lei; Li, Hao; Chen, Ming; Yang, Bo

2018-04-01

PSTD (Pseudo Spectral Time Domain) is an excellent model for the light scattering simulation of nonspherical aerosol particles. However, due to the particularity of its discretization form of the Maxwell's equations, the traditional Total Field/Scattering Field (TF/SF) technique for FDTD (Finite Differential Time Domain) is not applicable to PSTD, and the time-consuming pure scattering field technique is mainly applied to introduce the incident wave. To this end, the weighted TF/SF technique proposed by X. Gao is generalized and applied to the 3D-PSTD scattering model. Using this technique, the incident light can be effectively introduced by modifying the electromagnetic components in an inserted connecting region between the total field and the scattering field region with incident terms, where the incident terms are obtained by weighting the incident field by a window function. To optimally determine the thickness of connection region and the window function type for PSTD calculations, their influence on the modeling accuracy is firstly analyzed. To further verify the effectiveness and advantages of the weighted TF/SF technique, the improved PSTD model is validated against the PSTD model equipped with pure scattering field technique in both calculation accuracy and efficiency. The results show that, the performance of PSTD seems to be not sensitive to variation of window functions. The number of the connection layer required decreases with the increasing of spatial resolution, where for spatial resolution of 24 grids per wavelength, a 6-layer region is thick enough. The scattering phase matrices and integral scattering parameters obtained by the improved PSTD show an excellent consistency with those well-tested models for spherical and nonspherical particles, illustrating that the weighted TF/SF technique can introduce the incident precisely. The weighted TF/SF technique shows higher computational efficiency than pure scattering technique.

Light Weight Ceramic Ablators for Mars Follow-on Mission Vehicle Thermal Protection System

NASA Technical Reports Server (NTRS)

Tran, Huy K.; Rasky, Daniel J.; Hsu, Ming-Ta; Turan, Ryan

1994-01-01

New Light Weight Ceramic Ablators (LCA) were produced by using ceramic and carbon fibrous substrates, impregnated with silicone and phenolic resins. The special infiltration techniques (patent pending) were developed to control the amount of organic resins in the highly porous fiber matrices so that the final densities of LCA's range from 0.22 to 0.24 g/cc. This paper presents the thermal and ablative performance of the Silicone Impregnated Reusable Ceramic Ablators (SIRCA) in simulated entry conditions for Mars-Pathfinder in the Ames 60 MW Interaction Heating Facility (I HF). Arc jet test results yielded no evidence of char erosion and mass loss at high stagnation pressures to 0.25 atm. Minimal silica melt was detected on surface char at a stagnation pressure of 0.31 atm. Four ceramic substrates were used in the production of SIRCA's to obtain the effective of boron oxide present in substrate so the thermal performance of SIRCA's. A sample of SIRCA was also exposed to the same heating condition for five cycles and no significant mass loss or recession was observed. Tensile testing established that the SIRCA tensile strength is about a factor of two higher than that of the virgin substrates. Thermogravimetric Analysis (TGA) of the char in nitrogen and air showed no evidence of free carbon in the char. Scanning Electron Microscopy of the post test sample showed that the char surface consists of a fibrous structure that was sealed with a thin layer of silicon oxide melt.

A L-Band Superstrate Lens Enhanced Antenna and Array for Tactical Operations

DTIC Science & Technology

2013-07-01

unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The design of a 1.2 GHz microstrip antenna utilizing a superstrate layer for gain enhancement is...CA, 92152-5001 sam.chieh@navy.mil Abstract—The design of a 1.2 GHz microstrip antenna utilizing a superstrate layer for gain enhancement is...realized. The microstrip patch antenna is a widely used antenna in this regime as it is light weight and is easily scalable for increased gains. It has

The structure and possible functions of the milkfish Chanos chanos adipose eyelid.

PubMed

Chang, C-H; Chiao, C-C; Yan, H Y

2009-07-01

Basic histological sections (with different staining methods) and scanning electron microscopy (SEM) examinations showed that there were three distinctive layers in the adipose eyelid of milkfish Chanos chanos, which is found in the cephalie region and covers the entire eye. The outer and inner layers were epithelial tissues and the middle layer was composed of connective tissue formed by type I collagen fibrils. No adipose tissue was found in any of the three layers of the so-called adipose eyelid. Examination by transmission spectrophotometer showed that the adipose tissue could filter out ambient light with a wavelength shorter than 305 nm. A photoretinoscope was used to investigate whether the adipose eyelid influenced the mechanism of eye focusing. Eye diopter values did not differ before or after eyelid removal, which indicated that the adipose eyelid did not play a role in eye focusing. In light of these findings, it is suggested that the adipose eyelid serves to block exposure of harmful ultraviolet light into eyes and may also to offer some protection against impact to the eye in the aquatic environment.

Spectral imaging using clinical megavoltage beams and a novel multi-layer imager

NASA Astrophysics Data System (ADS)

Myronakis, Marios; Fueglistaller, Rony; Rottmann, Joerg; Hu, Yue-Houng; Wang, Adam; Baturin, Paul; Huber, Pascal; Morf, Daniel; Star-Lack, Josh; Berbeco, Ross

2017-12-01

We assess the feasibility of clinical megavoltage (MV) spectral imaging for material and bone separation with a novel multi-layer imager (MLI) prototype. The MLI provides higher detective quantum efficiency and lower noise than conventional electronic portal imagers. Simulated experiments were performed using a validated Monte Carlo model of the MLI to estimate energy absorption and energy separation between the MLI components. Material separation was evaluated experimentally using solid water and aluminum (Al), copper (Cu) and gold (Au) for 2.5 MV, 6 MV and 6 MV flattening filter free (FFF) clinical photon beams. An anthropomorphic phantom with implanted gold fiducials was utilized to further demonstrate bone/gold separation. Weighted subtraction imaging was employed for material and bone separation. The weighting factor (w) was iteratively estimated, with the optimal w value determined by minimization of the relative signal difference (Δ {{S}R} ) and signal-difference-to-noise ratio (SDNR) between material (or bone) and the background. Energy separation between layers of the MLI was mainly the result of beam hardening between components with an average energy separation between 34 and 47 keV depending on the x-ray beam energy. The minimum average energy of the detected spectrum in the phosphor layer was 123 keV in the top layer of the MLI with the 2.5 MV beam. The w values that minimized Δ {{S}R} and SDNR for Al, Cu and Au were 0.89, 0.76 and 0.64 for 2.5 MV; for 6 MV FFF, w was 0.98, 0.93 and 0.77 respectively. Bone suppression in the anthropomorphic phantom resulted in improved visibility of the gold fiducials with the 2.5 MV beam. Optimization of the MLI design is required to achieve optimal separation at clinical MV beam energies.

The original colours of fossil beetles

PubMed Central

McNamara, Maria E.; Briggs, Derek E. G.; Orr, Patrick J.; Noh, Heeso; Cao, Hui

2012-01-01

Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group. PMID:21957131

A Conductometric Indium Oxide Semiconducting Nanoparticle Enzymatic Biosensor Array

PubMed Central

Lee, Dongjin; Ondrake, Janet; Cui, Tianhong

2011-01-01

We report a conductometric nanoparticle biosensor array to address the significant variation of electrical property in nanomaterial biosensors due to the random network nature of nanoparticle thin-film. Indium oxide and silica nanoparticles (SNP) are assembled selectively on the multi-site channel area of the resistors using layer-by-layer self-assembly. To demonstrate enzymatic biosensing capability, glucose oxidase is immobilized on the SNP layer for glucose detection. The packaged sensor chip onto a ceramic pin grid array is tested using syringe pump driven feed and multi-channel I–V measurement system. It is successfully demonstrated that glucose is detected in many different sensing sites within a chip, leading to concentration dependent currents. The sensitivity has been found to be dependent on the channel length of the resistor, 4–12 nA/mM for channel lengths of 5–20 μm, while the apparent Michaelis-Menten constant is 20 mM. By using sensor array, analytical data could be obtained with a single step of sample solution feeding. This work sheds light on the applicability of the developed nanoparticle microsensor array to multi-analyte sensors, novel bioassay platforms, and sensing components in a lab-on-a-chip. PMID:22163696

The original colours of fossil beetles.

PubMed

McNamara, Maria E; Briggs, Derek E G; Orr, Patrick J; Noh, Heeso; Cao, Hui

2012-03-22

Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group.

Investigating the origin of efficiency droop by profiling the voltage across the multi-quantum well of an operating light-emitting diode

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

Kim, Taewoong; Seong, Tae-Yeon; School of Materials Science and Engineering, Korea University, Seoul 136-713

Efficiency droop is a phenomenon in which the efficiency of a light-emitting diode (LED) decreases with the increase in current density. To analyze efficiency droop, direct experimental observations on the energy conversion occurring inside the LED is required. Here, we present the measured voltage profiles on the cross section of an operating LED and analyze them with the cross-sectional temperature profiles obtained in a previous study under the same operation conditions. The measured voltage profiles suggest that with increases in the injection current density, electron depletion shifts from the multi-quantum well through an electron blocking layer to the p-GaN region.more » This is because electron leakage increases with increases in current density.« less

Simulation of the effect of photoprotective titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles on the thermal response and optical characteristics of skin

NASA Astrophysics Data System (ADS)

Krasnikov, I. V.; Seteikin, A. Yu.; Popov, A. P.

2015-04-01

The thermal response of skin covered with a mixture of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles of optimal sizes and irradiated by sunlight has been calculated. The nanoparticles were rubbed into the skin for maximum protection against the incident radiation. The dependences of the temperature dynamics in different skin layers (corneal layer, epidermis, dermis) have been obtained and analyzed upon skin irradiation with light at a wavelength of 310-800 nm. It has been found that increasing light scattering and absorption due to the nanoparticles introduced into the corneal layer resulted in a decrease in the thermal load and penetration depth of the incident radiation.

Fuel economy effects and incremental cost, weight and leadtime impacts of employing a continuously variable transmission (CVT) in mid-size passenger cars or compact light trucks

DOT National Transportation Integrated Search

1999-06-01

This report is a paper study of the fuel economy benefits on the Environmental Protection Agency (EPA) City and Highway Cycles of using a continuously variable transmission (CVT) in a 3625 lb (1644 kg) car and compact light truck. The baseline vehicl...

Light availability impacts structure and function of phototrophic stream biofilms across domains and trophic levels.

PubMed

Bengtsson, Mia M; Wagner, Karoline; Schwab, Clarissa; Urich, Tim; Battin, Tom J

2018-04-21

Phototrophic biofilms are ubiquitous in freshwater and marine environments where they are critical for biogeochemical cycling, food webs and in industrial applications. In streams, phototrophic biofilms dominate benthic microbial life and harbor an immense prokaryotic and eukaryotic microbial biodiversity with biotic interactions across domains and trophic levels. Here, we examine how community structure and function of these biofilms respond to varying light availability, as the crucial energy source for phototrophic biofilms. Using metatranscriptomics, we found that under light limitation dominant phototrophs, including diatoms and cyanobacteria, displayed a remarkable plasticity in their photosynthetic machinery manifested as higher abundance of messenger RNAs (mRNAs) involved in photosynthesis and chloroplast ribosomal RNA. Under higher light availability, bacterial mRNAs involved in phosphorus metabolism, mainly from Betaproteobacteria and Cyanobacteria, increased, likely compensating for nutrient depletion in thick biofilms with high biomass. Consumers, including diverse ciliates, displayed community shifts indicating preferential grazing on algae instead of bacteria under higher light. For the first time, we show that the functional integrity of stream biofilms under variable light availability is maintained by structure-function adaptations on several trophic levels. Our findings shed new light on complex biofilms, or "microbial jungles", where in analogy to forests, diverse and multi-trophic level communities lend stability to ecosystem functioning. This multi-trophic level perspective, coupling metatranscriptomics to process measurements, could advance understanding of microbial-driven ecosystems beyond biofilms, including planktonic and soil environments. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Determination of sulfuric acid concentration for anti-cavitation characteristics of Al alloy by two step anodizing process to forming nano porous.

PubMed

Lee, Seung-Jun; Kim, Seong-Kweon; Jeong, Jae-Yong; Kim, Seong-Jong

2014-12-01

Al alloy is a highly active metal but forms a protective oxide film having high corrosion resistance in atmosphere environment. However, the oxide film is not suitable for practical use, since the thickness of the film is not uniform and it is severly altered with formation conditions. This study focused on developing an aluminum anodizing layer having hardness, corrosion resistance and abrasion resistance equivalent to a commercial grade protective layer. Aluminum anodizing layer was produced by two-step aluminum anodizing oxide (AAO) process with different sulfuric acid concentrations, and the cavitation characteristics of the anodized coating layer was investigated. In hardness measurement, the anodized coating layer produced with 15 vol.% of sulfuric acid condition had the highest value of hardness but exhibited poor cavitation resistance due to being more brittle than those with other conditions. The 10 vol.% of sulfuric acid condition was thus considered to be the optimum condition as it had the lowest weight loss and damage depth.

Development of acousto-optic spatial light modulator unit for effective control of light beam intensity and diffraction angle in 3D holographic display applications

NASA Astrophysics Data System (ADS)

Kondalkar, Vijay V.; Ryu, Geonhee; Lee, Yongbeom; Lee, Keekeun

2018-07-01

An acousto-optic (AO) based holographic display unit was developed using surface acoustic wave (SAW) with different wavelength to modulate the diffraction angles, intensities, and phases of light. The new configurations were employed to control two beams simultaneously by using a single chirp inter-digital transducer (IDT), and a micro-lens array was integrated at the end of the waveguide layer to focus the diffracted light on to the screen. Two incident light beams were simultaneously modulated by using different refractive grating periods generated from chirp IDT. A diffraction angle of about 5° was obtained by using a SAW with a frequency of 430 MHz. The increase in the SAW input power enhances the diffraction efficiency of the light beam at the exit. The obtained maximum diffraction efficiency is ~70% at a frequency of 430 MHz. The sloped shape of the waveguide entrance and a tall rounded Ni poles help in coupling the incident light to the waveguide layer. The diffracted beam was collected through the lens, which increased the intensity of light in the viewing plane. COMSOL multi-physics and coupling of mode (COM) modeling were performed to predict the device performance and compared with the experimental results.

Restraint deformation and corrosion protection of gold deposited aluminum mirrors for cold optics of mid-infrared instruments

NASA Astrophysics Data System (ADS)

Uchiyama, Mizuho; Miyata, Takashi; Sako, Shigeyuki; Kamizuka, Takafumi; Nakamura, Tomohiko; Asano, Kentaro; Okada, Kazushi; Onaka, Takashi; Sakon, Itsuki; Kataza, Hirokazu; Sarugaku, Yuki; Kirino, Okiharu; Nakagawa, Hiroyuki; Okada, Norio; Mitsui, Kenji

2014-07-01

We report the restraint deformation and the corrosion protection of gold deposited aluminum mirrors for mid-infrared instruments. To evaluate the deformation of the aluminum mirrors by thermal shrinkage, monitoring measurement of the surface of a mirror has been carried out in the cooling cycles from the room temperature to 100 K. The result showed that the effect of the deformation was reduced to one fourth if the mirror was screwed with spring washers. We have explored an effective way to prevent the mirror from being galvanically corroded. A number of samples have been prepared by changing the coating conditions, such as inserting an insulation layer, making a multi-layer and overcoating water blocking layer, or carrying out precision cleaning before coating. Precision cleaning before the deposition and protecting coat with SiO over the gold layer seemed to be effective in blocking corrosion of the aluminum. The SiO over-coated mirror has survived the cooling test for the mid-infrared use and approximately 1 percent decrease in the reflectance has been detected at 6-25 microns compared to gold deposited mirror without coating.

HF-Release of Sacrificial Layers in CMOS-integrated MOEMS structures

NASA Astrophysics Data System (ADS)

Döring, S.; Friedrichs, M.; Pufe, W.; Schulze, M.

2016-10-01

In this paper we will present details of the release process of SiO2 sacrificial layers we use within a multi-level MOEMS process developed by IPMS. Using such sacrificial layers gain a lot of benefits necessary for the production of high-end MOEMS devices like high surface quality and great surface planarity. However the HF-release of the sacrificial layer can be connected with specific issues. We present, which mechanisms are involved in the release process and how knowing them, can be the key for an optimized performance of the device. More-over we will present how to protect the CMOS backplane of our devices from unwanted HF attack during the release.

The ultraviolet environment of Mars: biological implications past, present, and future.

PubMed

Cockell, C S; Catling, D C; Davis, W L; Snook, K; Kepner, R L; Lee, P; McKay, C P

2000-08-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.

The ultraviolet environment of Mars: biological implications past, present, and future

NASA Technical Reports Server (NTRS)

Cockell, C. S.; Catling, D. C.; Davis, W. L.; Snook, K.; Kepner, R. L.; Lee, P.; McKay, C. P.

2000-01-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.

Toughened Thermal Blanket for MMOD Protection

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Lear, Dana M.

2014-01-01

Thermal blankets are used extensively on spacecraft to provide passive thermal control of spacecraft hardware from thermal extremes encountered in space. Toughened thermal blankets have been developed that greatly improve protection from hypervelocity micrometeoroid and orbital debris (MMOD) impacts. These blankets can be outfitted if so desired with a reliable means to determine the location, depth and extent of MMOD impact damage by incorporating an impact sensitive piezoelectric film. Improved MMOD protection of thermal blankets was obtained by adding selective materials at various locations within the thermal blanket. As given in Figure 1, three types of materials were added to the thermal blanket to enhance its MMOD performance: (1) disrupter layers, near the outside of the blanket to improve breakup of the projectile, (2) standoff layers, in the middle of the blanket to provide an area or gap that the broken-up projectile can expand, and (3) stopper layers, near the back of the blanket where the projectile debris is captured and stopped. The best suited materials for these different layers vary. Density and thickness is important for the disrupter layer (higher densities generally result in better projectile breakup), whereas a highstrength to weight ratio is useful for the stopper layer, to improve the slowing and capture of debris particles.

Effect of a multi-layer infection control barrier on the micro-hardness of a composite resin

PubMed Central

HWANG, In-Nam; HONG, Sung-Ok; LEE, Bin-Na; HWANG, Yun-Chan; OH, Won-Mann; CHANG, Hoon-Sang

2012-01-01

Objective The aim of this study was to evaluate the effect of multiple layers of an infection control barrier on the micro-hardness of a composite resin. Material and Methods One, two, four, and eight layers of an infection control barrier were used to cover the light guides of a high-power light emitting diode (LED) light curing unit (LCU) and a low-power halogen LCU. The composite specimens were photopolymerized with the LCUs and the barriers, and the micro-hardness of the upper and lower surfaces was measured (n=10). The hardness ratio was calculated by dividing the bottom surface hardness of the experimental groups by the irradiated surface hardness of the control groups. The data was analyzed by two-way ANOVA and Tukey's HSD test. Results The micro-hardness of the composite specimens photopolymerized with the LED LCU decreased significantly in the four- and eight-layer groups of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. The hardness ratio of the composite specimens was <80% in the eight-layer group. The micro-hardness of the composite specimens photopolymerized with the halogen LCU decreased significantly in the eight-layer group of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. However, the hardness ratios of all the composite specimens photopolymerized with barriers were <80%. Conclusions The two-layer infection control barrier could be used on high-power LCUs without decreasing the surface hardness of the composite resin. However, when using an infection control barrier on the low-power LCUs, attention should be paid so as not to sacrifice the polymerization efficiency. PMID:23138746

Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells

NASA Astrophysics Data System (ADS)

Siyabi, Idris Al; Shanks, Katie; Mallick, Tapas; Sundaram, Senthilarasu

2017-09-01

Concentrator Photovoltaic (CPV) technology is increasingly being considered as an alternative option for solar electricity generation. However, increasing the light concentration ratio could decrease the system output power due to the increase in the temperature of the cells. The performance of a multi-layer microchannel heat sink configuration was evaluated using numerical analysis. In this analysis, three dimensional incompressible laminar steady flow model was solved numerically. An electrical and thermal solar cell model was coupled for solar cell temperature and efficiency calculations. Thermal resistance, solar cell temperature and pumping power were used for the system efficiency evaluation. An increase in the number of microchannel layers exhibited the best overall performance in terms of the thermal resistance, solar cell temperature uniformity and pressure drop. The channel height and width has no effect on the solar cell maximum temperature. However, increasing channel height leads to a reduction in the pressure drop and hence less fluid pumping power.

A two-stage storage routing model for green roof runoff detention.

PubMed

Vesuviano, Gianni; Sonnenwald, Fred; Stovin, Virginia

2014-01-01

Green roofs have been adopted in urban drainage systems to control the total quantity and volumetric flow rate of runoff. Modern green roof designs are multi-layered, their main components being vegetation, substrate and, in almost all cases, a separate drainage layer. Most current hydrological models of green roofs combine the modelling of the separate layers into a single process; these models have limited predictive capability for roofs not sharing the same design. An adaptable, generic, two-stage model for a system consisting of a granular substrate over a hard plastic 'egg box'-style drainage layer and fibrous protection mat is presented. The substrate and drainage layer/protection mat are modelled separately by previously verified sub-models. Controlled storm events are applied to a green roof system in a rainfall simulator. The time-series modelled runoff is compared to the monitored runoff for each storm event. The modelled runoff profiles are accurate (mean Rt(2) = 0.971), but further characterization of the substrate component is required for the model to be generically applicable to other roof configurations with different substrate.

Polarized edge emission from GaN-based light-emitting diodes sandwiched by dielectric/metal hybrid reflectors

NASA Astrophysics Data System (ADS)

Yan, L. J.; Sheu, J. K.; Huang, F. W.; Lee, M. L.

2010-12-01

Edge-emitting c-plane GaN/sapphire-based light-emitting diodes (LEDs) sandwiched by two dielectric/metal hybrid reflectors on both sapphire and GaN surfaces were studied to determine their light emission polarization. The hybrid reflectors comprised dielectric multiple thin films and a metal layer. The metal layers of Au or Ag used in this study were designed to enhance the polarization ratio from S-polarization (transverse electric wave, TE) to P-polarization (transverse magnetic wave, TM). The two sets of optimized dielectric multi thin films served as matching layers for wide-angle incident light on both sapphire and GaN surfaces. To determine which reflector scheme would achieve a higher polarization ratio, simulations of the reflectance at the hybrid reflectors on sapphire (or GaN) interface were performed before the fabrication of experimental LEDs. Compared with conventional c-plane InGaN/GaN/sapphire LEDs without dielectric/metal hybrid reflectors, the experimental LEDs exhibited higher polarization ratio (ITE-max/ITM-max) with r=2.174 (˜3.37 dB) at a wavelength of 460 nm. In contrast, the original polarized light (without dielectric/metal hybrid reflectors) was partially contributed (r=1.398) by C-HH or C-LH (C band to the heavy-hole sub-band or C band to the crystal-field split-off sub-band) transitions along the a-plane or m-plane direction.

Electron transport efficiency at opposite leaf sides: effect of vertical distribution of leaf angle, structure, chlorophyll content and species in a forest canopy.

PubMed

Mänd, Pille; Hallik, Lea; Peñuelas, Josep; Kull, Olevi

2013-02-01

We investigated changes in chlorophyll a fluorescence from alternate leaf surfaces to assess the intraleaf light acclimation patterns in combination with natural variations in radiation, leaf angles, leaf mass per area (LMA), chlorophyll content (Chl) and leaf optical parameters. Measurements were conducted on bottom- and top-layer leaves of Tilia cordata Mill. (a shade-tolerant sub-canopy species, sampled at heights of 11 and 16 m) and Populus tremula L. (a light-demanding upper canopy species, sampled at canopy heights of 19 and 26 m). The upper canopy species P. tremula had a six times higher PSII quantum yield (Φ(II)) and ratio of open reaction centres (qP), and a two times higher LMA than T. cordata. These species-specific differences were also present when the leaves of both species were in similar light conditions. Leaf adaxial/abaxial fluorescence ratio was significantly larger in the case of more horizontal leaves. Populus tremula (more vertical leaves), had smaller differences in fluorescence parameters between alternate leaf sides compared with T. cordata (more horizontal leaves). However, optical properties on alternate leaf sides showed a larger difference for P. tremula. Intraspecifically, the measured optical parameters were better correlated with LMA than with leaf Chl. Species-specific differences in leaf anatomy appear to enhance the photosynthetic potential of leaf biochemistry by decreasing the interception of excess light in P. tremula and increasing the light absorptance in T. cordata. Our results indicate that intraleaf light absorption gradient, described here as leaf adaxial/abaxial side ratio of chlorophyll a fluorescence, varies significantly with changes in leaf light environment in a multi-layer multi-species tree canopy. However, this variation cannot be described merely as a simple function of radiation, leaf angle, Chl or LMA, and species-specific differences in light acclimation strategies should also be considered.

Laser light-section sensor automating the production of textile-reinforced composites

NASA Astrophysics Data System (ADS)

Schmitt, R.; Niggemann, C.; Mersmann, C.

2009-05-01

Due to their advanced weight-specific mechanical properties, the application of fibre-reinforced plastics (FRP) has been established as a key technology in several engineering areas. Textile-based reinforcement structures (Preform) in particular achieve a high structural integrity due to the multi-dimensional build-up of dry-fibre layers combined with 3D-sewing and further textile processes. The final composite parts provide enhanced damage tolerances through excellent crash-energy absorbing characteristics. For these reasons, structural parts (e.g. frame) will be integrated in next generation airplanes. However, many manufacturing processes for FRP are still involving manual production steps without integrated quality control. The non-automated production implies considerable process dispersion and a high rework rate. Before the final inspection there is no reliable information about the production status. This work sets metrology as the key to automation and thus an economically feasible production, applying a laser light-section sensor system (LLSS) to measure process quality and feed back the results to close control loops of the production system. The developed method derives 3D-measurements from height profiles acquired by the LLSS. To assure the textile's quality a full surface scan is conducted, detecting defects or misalignment by comparing the measurement results with a CAD model of the lay-up. The method focuses on signal processing of the height profiles to ensure a sub-pixel accuracy using a novel algorithm based on a non-linear least-square fitting to a set of sigmoid functions. To compare the measured surface points to the CAD model, material characteristics are incorporated into the method. This ensures that only the fibre layer of the textile's surface is included and gaps between the fibres or overlaying seams are neglected. Finally, determining the uncertainty in measurement according to the GUM-standard proofed the sensor system's accuracy. First tests under industrial conditions showed that applying this sensor after the drapery of each textile layer reduces the scrap quota by approximately 30%.

Photocathodic Protection of 304 Stainless Steel by Bi2S3/TiO2 Nanotube Films Under Visible Light

NASA Astrophysics Data System (ADS)

Li, Hong; Wang, Xiutong; Wei, Qinyi; Hou, Baorong

2017-01-01

We report the preparation of TiO2 nanotubes coupled with a narrow bandgap semiconductor, i.e., Bi2S3, to improve the photocathodic protection property of TiO2 for metals under visible light. Bi2S3/TiO2 nanotube films were successfully synthesized using the successive ionic layer adsorption and reaction (SILAR) method. The morphology and structure of the composite films were studied by scanning electron microscopy and X-ray diffraction, respectively. UV-visible diffuse reflectance spectra were recorded to analyze the optical absorption property of the composite films. In addition, the influence of Bi2S3 deposition cycles on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. Results revealed that the heterostructure comprised crystalline anatase TiO2 and orthorhombic Bi2S3 and exhibited a high visible light response. The photocurrent density of Bi2S3/TiO2 was significantly higher than that of pure TiO2 under visible light. The sensitization of Bi2S3 enhanced the separation efficiency of the photogenerated charges and photocathodic protection properties of TiO2. The Bi2S3/TiO2 nanotubes prepared by SILAR deposition with 20 cycles exhibited the optimal photogenerated cathodic protection performance on the 304 stainless steel under visible light.

Photocathodic Protection of 304 Stainless Steel by Bi2S3/TiO2 Nanotube Films Under Visible Light.

PubMed

Li, Hong; Wang, Xiutong; Wei, Qinyi; Hou, Baorong

2017-12-01

We report the preparation of TiO 2 nanotubes coupled with a narrow bandgap semiconductor, i.e., Bi 2 S 3 , to improve the photocathodic protection property of TiO 2 for metals under visible light. Bi 2 S 3 /TiO 2 nanotube films were successfully synthesized using the successive ionic layer adsorption and reaction (SILAR) method. The morphology and structure of the composite films were studied by scanning electron microscopy and X-ray diffraction, respectively. UV-visible diffuse reflectance spectra were recorded to analyze the optical absorption property of the composite films. In addition, the influence of Bi 2 S 3 deposition cycles on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. Results revealed that the heterostructure comprised crystalline anatase TiO 2 and orthorhombic Bi 2 S 3 and exhibited a high visible light response. The photocurrent density of Bi 2 S 3 /TiO 2 was significantly higher than that of pure TiO 2 under visible light. The sensitization of Bi 2 S 3 enhanced the separation efficiency of the photogenerated charges and photocathodic protection properties of TiO 2 . The Bi 2 S 3 /TiO 2 nanotubes prepared by SILAR deposition with 20 cycles exhibited the optimal photogenerated cathodic protection performance on the 304 stainless steel under visible light.

Integrating Spatial Multi Criteria Decision Making (SMCDM) with Geographic Information Systems (GIS) for delineation of the most suitable areas for aquifer storage and recovery (ASR)

NASA Astrophysics Data System (ADS)

Ahani Amineh, Zainab Banoo; Hashemian, Seyyed Jamal Al-Din; Magholi, Alireza

2017-08-01

Hamoon-Jazmoorian plain is located in southeast of Iran. Overexploitation of groundwater in this plain has led to water level decline and caused serious problems such as land subsidence, aquifer destruction and water quality degradation. The increasing population and agricultural development along with drought and climate change, have further increased the pressure on water resources in this region over the last years. In order to overcome such crisis, introduction of surface water into an aquifer at particular locations can be a suitable solution. A wide variety of methods have been developed to recharge groundwater, one of which is aquifer storage and recovery (ASR). One of the fundamental principles of making such systems is delineation of suitable areas based on scientific and natural facts in order to achieve relevant objectives. To that end, the Multi Criteria Decision Making (MCDM) in conjunction with the Geographic Information Systems (GIS) was applied in this study. More specifically, nine main parameters including depth of runoff as the considered source of water, morphology of the earth surface features such as geology, geomorphology, land use and land cover, drainage and aquifer characteristics along with quality of water in the aquifer were considered as the main layers in GIS. The runoff water available for artificial recharge in the basin was estimated through Soil Conservation Service (SCS) curve number method. The weighted curve number for each watershed was derived through spatial intersection of land use and hydrological soil group layers. Other thematic layers were extracted from satellite images, topographical map, and other collateral data sources, then weighed according to their influence in locating process. The Analytical Hierarchy Process (AHP) method was then used to calculate weights of individual parameters. The normalized weighted layers were then overlaid to build up the recharge potential map. The results revealed that 34% of the total area is suitable and very suitable for groundwater recharge.

Study on multimodal transport route under low carbon background

NASA Astrophysics Data System (ADS)

Liu, Lele; Liu, Jie

2018-06-01

Low-carbon environmental protection is the focus of attention around the world, scientists are constantly researching on production of carbon emissions and living carbon emissions. However, there is little literature about multimodal transportation based on carbon emission at home and abroad. Firstly, this paper introduces the theory of multimodal transportation, the multimodal transport models that didn't consider carbon emissions and consider carbon emissions are analyzed. On this basis, a multi-objective programming 0-1 programming model with minimum total transportation cost and minimum total carbon emission is proposed. The idea of weight is applied to Ideal point method for solving problem, multi-objective programming is transformed into a single objective function. The optimal solution of carbon emission to transportation cost under different weights is determined by a single objective function with variable weights. Based on the model and algorithm, an example is given and the results are analyzed.

Hypervelocity impact response of aluminum multi-wall structures

NASA Technical Reports Server (NTRS)

Schonberg, William P.; Bean, Alan J.

1991-01-01

The results of an investigation in which the perforation resistance of aluminum multiwall structures is analyzed under a variety of hypervelocity impact loading conditions are presented. A comparative analysis of the impact damage in structural systems with two or more bumpers and the damage in single-bumper systems of similar weight is performed to determine the advantages and disadvantages of employing more than one bumper in structural wall systems for long-duration spacecraft. A significant increase in protection against perforation by hypervelocity projectiles can be achieved if a single bumper is replaced by two bumpers of similar weight while the total wall spacing is kept constant. It is found that increasing the number of bumpers beyond two while keeping the total stand-off distance constant does not result in a substantial increase in protection over that offered by two bumpers of similar weight.

Improved event positioning in a gamma ray detector using an iterative position-weighted centre-of-gravity algorithm.

PubMed

Liu, Chen-Yi; Goertzen, Andrew L

2013-07-21

An iterative position-weighted centre-of-gravity algorithm was developed and tested for positioning events in a silicon photomultiplier (SiPM)-based scintillation detector for positron emission tomography. The algorithm used a Gaussian-based weighting function centred at the current estimate of the event location. The algorithm was applied to the signals from a 4 × 4 array of SiPM detectors that used individual channel readout and a LYSO:Ce scintillator array. Three scintillator array configurations were tested: single layer with 3.17 mm crystal pitch, matched to the SiPM size; single layer with 1.5 mm crystal pitch; and dual layer with 1.67 mm crystal pitch and a ½ crystal offset in the X and Y directions between the two layers. The flood histograms generated by this algorithm were shown to be superior to those generated by the standard centre of gravity. The width of the Gaussian weighting function of the algorithm was optimized for different scintillator array setups. The optimal width of the Gaussian curve was found to depend on the amount of light spread. The algorithm required less than 20 iterations to calculate the position of an event. The rapid convergence of this algorithm will readily allow for implementation on a front-end detector processing field programmable gate array for use in improved real-time event positioning and identification.

Photoinduced charge-transfer materials for nonlinear optical applications

DOEpatents

McBranch, Duncan W.

2006-10-24

A method using polyelectrolyte self-assembly for preparing multi-layered organic molecular materials having individual layers which exhibit ultrafast electron and/or energy transfer in a controlled direction occurring over the entire structure. Using a high molecular weight, water-soluble, anionic form of poly-phenylene vinylene, self-assembled films can be formed which show high photoluminescence quantum efficiency (QE). The highest emission QE is achieved using poly(propylene-imine) (PPI) dendrimers as cationic binders. Self-quenching of the luminescence is observed as the solid polymer film thickness is increased and can be reversed by inserting additional spacer layers of transparent polyelectrolytes between each active conjugated layer, such that the QE grows with thickness. A red shift of the luminescence is also observed as additional PPV layers are added. This effect persists as self-quenching is eliminated. Charge transfer superlattices can be formed by additionally incorporating C.sub.60 acceptor layers.

A Fast Proceduere for Optimizing Thermal Protection Systems of Re-Entry Vehicles

NASA Astrophysics Data System (ADS)

Ferraiuolo, M.; Riccio, A.; Tescione, D.; Gigliotti, M.

The aim of the present work is to introduce a fast procedure to optimize thermal protection systems for re-entry vehicles subjected to high thermal loads. A simplified one-dimensional optimization process, performed in order to find the optimum design variables (lengths, sections etc.), is the first step of the proposed design procedure. Simultaneously, the most suitable materials able to sustain high temperatures and meeting the weight requirements are selected and positioned within the design layout. In this stage of the design procedure, simplified (generalized plane strain) FEM models are used when boundary and geometrical conditions allow the reduction of the degrees of freedom. Those simplified local FEM models can be useful because they are time-saving and very simple to build; they are essentially one dimensional and can be used for optimization processes in order to determine the optimum configuration with regard to weight, temperature and stresses. A triple-layer and a double-layer body, subjected to the same aero-thermal loads, have been optimized to minimize the overall weight. Full two and three-dimensional analyses are performed in order to validate those simplified models. Thermal-structural analyses and optimizations are executed by adopting the Ansys FEM code.

Cylindrical Organic Solar Cells with Carbon Nanotube Charge Collectors

NASA Astrophysics Data System (ADS)

Zakhidov, Dante; Lou, Raymond; Ravi, Nav; Mielczarek, Kamil; Cook, Alexander

2009-10-01

Traditional organic photovoltaic devices (OPV) are built on a flat glass substrates coated by ITO. The maximum area covered by the solar cells is limited to a two dimensional plane. Moreover the light absorption is not maximized for a very thin photoactive layer. We suggest here a cylindrical design which has a vertical structure of optical fiber coated by OPV, with light incident from the side and from edge. The sunlight, entering via a smaller area is captured into optical fiber, which allows more sunlight to be absorbed by a cylindrical OPV overcoating with multiple reflections inside the optical fiber. Instead of using brittle ITO as a hole collecting layer in the cylindrical OPV, transparent sheets of multi-walled carbon nanotubes are applied. Their highly conductive nature and 3-D collection of carriers from the P3HT/PCBM photoactive layer allows for increased efficiency over a planar geometry while keeping the device transparent. Aluminum is used as the electron collecting layer and as a cylindrical mirror. [4pt] [1] Ulbricht, et.al, phys. stat. sol. (b) 243, No. 13, 3528 - 3532 (2006) / DOI 10.1002/pssb.200669181

Swedish Defence Research Abstracts 1980/81-3 (Froe Forsvars Forsknings Referat 1980/81-3).

DTIC Science & Technology

1981-11-01

computes the refractive index or the thickness of thin mono- or multi -layer films. The program is written in Fortran and is adapted to the ellipsometer at...Unmnnounced EtN8PECT: Justlflotl Distribution/ Availability Codes Avail and/or Dist Special 2 Index to FRO 80/81-3 A PROTECTION - ATOMIC Al The nuclear...aberrations in PHA-stimulated human lymphocytes in the GI stage (in English) B PROTECTION - BIOLOGICAL BI Threat scenario (119) Epidemiological aspects

High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

NASA Astrophysics Data System (ADS)

Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

2014-09-01

This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

Multi-frame partially saturated images blind deconvolution

NASA Astrophysics Data System (ADS)

Ye, Pengzhao; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

2016-12-01

When blurred images have saturated or over-exposed pixels, conventional blind deconvolution approaches often fail to estimate accurate point spread function (PSF) and will introduce local ringing artifacts. In this paper, we propose a method to deal with the problem under the modified multi-frame blind deconvolution framework. First, in the kernel estimation step, a light streak detection scheme using multi-frame blurred images is incorporated into the regularization constraint. Second, we deal with image regions affected by the saturated pixels separately by modeling a weighted matrix during each multi-frame deconvolution iteration process. Both synthetic and real-world examples show that more accurate PSFs can be estimated and restored images have richer details and less negative effects compared to state of art methods.

White light emission of monolithic InGaN/GaN grown on morphology-controlled, nanostructured GaN templates.

PubMed

Song, Keun Man; Kim, Do-Hyun; Kim, Jong-Min; Cho, Chu-Young; Choi, Jehyuk; Kim, Kahee; Park, Jinsup; Kim, Hogyoug

2017-06-02

We demonstrated an InGaN/GaN-based, monolithic, white light-emitting diode (LED) without phosphors by using morphology-controlled active layers formed on multi-facet GaN templates containing polar and semipolar surfaces. The nanostructured surface morphology was controlled by changing the growth time, and distinct multiple photoluminescence peaks were observed at 360, 460, and 560 nm; these features were caused by InGaN/GaN-based multiple quantum wells (MQWs) on the nanostructured facets. The origin of each multi-peak was related to the different indium (In) compositions in the different planes of the quantum wells grown on the nanostructured GaN. The emitting units of MQWs in the LED structures were continuously connected, which is different from other GaN-based nanorod or nanowire LEDs. Therefore, the suggested structure had a larger active area. From the electroluminescence spectrum of the fabricated LED, monolithic white light emission with CIE color coordinates of x = 0.306 and y = 0.333 was achieved via multi-facet control combined with morphology control of the metal organic chemical vapor deposition-selective area growth of InGaN/GaN MQWs.

White light emission of monolithic InGaN/GaN grown on morphology-controlled, nanostructured GaN templates

NASA Astrophysics Data System (ADS)

Song, Keun Man; Kim, Do-Hyun; Kim, Jong-Min; Cho, Chu-Young; Choi, Jehyuk; Kim, Kahee; Park, Jinsup; Kim, Hogyoug

2017-06-01

We demonstrated an InGaN/GaN-based, monolithic, white light-emitting diode (LED) without phosphors by using morphology-controlled active layers formed on multi-facet GaN templates containing polar and semipolar surfaces. The nanostructured surface morphology was controlled by changing the growth time, and distinct multiple photoluminescence peaks were observed at 360, 460, and 560 nm; these features were caused by InGaN/GaN-based multiple quantum wells (MQWs) on the nanostructured facets. The origin of each multi-peak was related to the different indium (In) compositions in the different planes of the quantum wells grown on the nanostructured GaN. The emitting units of MQWs in the LED structures were continuously connected, which is different from other GaN-based nanorod or nanowire LEDs. Therefore, the suggested structure had a larger active area. From the electroluminescence spectrum of the fabricated LED, monolithic white light emission with CIE color coordinates of x = 0.306 and y = 0.333 was achieved via multi-facet control combined with morphology control of the metal organic chemical vapor deposition-selective area growth of InGaN/GaN MQWs.

Laboratory simulation of interplanetary ultraviolet radiation (broad spectrum) and its effects on Deinococcus radiodurans

NASA Astrophysics Data System (ADS)

Paulino-Lima, Ivan Gláucio; Pilling, Sérgio; Janot-Pacheco, Eduardo; de Brito, Arnaldo Naves; Barbosa, João Alexandre Ribeiro Gonçalves; Leitão, Alvaro Costa; Lage, Claudia de Alencar Santos

2010-08-01

The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m -2, corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes.

Orbital-dependent Electron-Hole Interaction in Graphene and Associated Multi-Layer Structures

PubMed Central

Deng, Tianqi; Su, Haibin

2015-01-01

We develop an orbital-dependent potential to describe electron-hole interaction in materials with structural 2D character, i.e. quasi-2D materials. The modulated orbital-dependent potentials are also constructed with non-local screening, multi-layer screening, and finite gap due to the coupling with substrates. We apply the excitonic Hamiltonian in coordinate-space with developed effective electron-hole interacting potentials to compute excitons’ binding strength at M (π band) and Γ (σ band) points in graphene and its associated multi-layer forms. The orbital-dependent potential provides a range-separated property for regulating both long- and short-range interactions. This accounts for the existence of the resonant π exciton in single- and bi-layer graphenes. The remarkable strong electron-hole interaction in σ orbitals plays a decisive role in the existence of σ exciton in graphene stack at room temperature. The interplay between gap-opening and screening from substrates shed a light on the weak dependence of σ exciton binding energy on the thickness of graphene stacks. Moreover, the analysis of non-hydrogenic exciton spectrum in quasi-2D systems clearly demonstrates the remarkable comparable contribution of orbital dependent potential with respect to non-local screening process. The understanding of orbital-dependent potential developed in this work is potentially applicable for a wide range of materials with low dimension. PMID:26610715

Light Competition and Carbon Partitioning-Allocation in an improved Forest Ecosystem Model

NASA Astrophysics Data System (ADS)

Collalti, Alessio; Santini, Monia; Valentini Valentini, Riccardo

2010-05-01

In Italy about 100.000 km2 are covered by forests. This surface is the 30% of the whole national land and this shows how the forests are important both for socio-economic and for environmental aspects. Forests changes affect a delicate balance that involve not only vegetation components but also bio-geochemical cycles and global climate. The knowledge of the amount of Carbon sequestered by forests represents a precious information for their sustainable management in the framework of climate changes. Primary studies in terms of model about this important issue, has been done through Forest Ecosystem Model (FEM), well known and validated as 3PG (Landsberg et Waring, 1997; Sands 2004). It is based on light use efficiency approach at the canopy level. The present study started from the original model 3PG, producing an improved version that uses many of explicit formulations of all relevant ecophysiological processes but makes it able to be applied for natural forests. The mutual interaction of forest growth and light conditions causes vertical and horizontal differentiation in the natural forest mosaic. Only ecophysiological parameters which can be either directly measured or estimates with reasonable certainty are used. The model has been written in C language and has been created considering a tri-dimensional cell structure with different vertical layers depending on the forest type that has to be simulated. This 3PG 'improved' version enable to work on multi-layer and multi-species forests type with cell resolution of one hectare for the typical Italian forest species. The multi-layer version is the result of the implementation and development of Lambert-Beer law for the estimation of intercepted, absorbed and transmitted light through different storeys of the forest. It is possible estimates, for each storey, a Par value (Photosynthetic Active Radiation) through Leaf Area Index (LAI), Light Extinction Coefficient and cell Canopy Cover using a "Big Leaf" approach. Hence, the presence of a cohort in a storey determines the amount of light received for the photosynthetic processes. The population density (numbers of trees per cell) represents a good competition index for determining the tree crown structure and tree crown dimension within a forest population. The tree crown tend to branch out horizontally to intercept as much light as possible. The model assess the structure of the tree crown both vertically and horizontally on the base of the population density and it up-scales the result to the whole stand. The canopy depth and the percentage of horizontal coverage determines moreover a crowding competition index that lead to a specific biomass partitioning-allocation ratio among the different tree components (foliage, roots and stem) and especially for the stem affecting Height-Diameter (at breast height) ratio. In this model, Height-Diameter ratio is used as an alternative competition index in determining the vigour and the strength of competition on free growth status of trees. The forest dominant vegetative cover affects moreover the presence of a dominated layer, it influences its yield and its Carbon stocking capacity and hence it influences the forest ecosystem CO2 carbon balance. From this model it is possible to simulate the impact of Climate Change on forests, the feedback of one or more dominated layers in terms of CO2 uptake in a forest stand and the effects of forest management activities for the next years.

Effect of blood and saliva contamination on bond strength of brackets bonded with a protective liquid polish and a light-cured adhesive.

PubMed

Sayinsu, Korkmaz; Isik, Fulya; Sezen, Serdar; Aydemir, Bulent

2007-03-01

The application of a polymer coating to the labial enamel tooth surface before bonding can help keep white spot lesions from forming. Previous studies evaluating the effects of blood and saliva contamination on the bond strengths of light-cured composites showed significant reductions in bond strength values. The purpose of this study was to investigate whether the bond strength of a light-cured system (Transbond XT, 3M Unitek, Puchheim, Germany) used with a liquid polish (BisCover, Bisco, Schaumburg, Ill) is affected by contamination with blood or saliva. One hundred twenty permanent human premolars were randomly divided into 6 groups of 20. Various enamel surface conditions were studied: dry, blood contaminated, and saliva contaminated. A light-cured bonding system (Transbond XT) was used in all groups. The teeth in group 1 were bonded with Transbond XT. In the second group, BisCover polymeric resin polish was applied on the etched tooth surfaces before the brackets were bonded with Transbond XT resin. Comparison of the first and second groups showed no statistically significant difference. Groups 3 through 6 were bonded without Transbond XT. For groups 3 and 5, a layer of blood or saliva, respectively, was applied to the etched enamel followed by BisCover. In groups 4 and 6, blood or saliva, respectively, was applied on the light-cured BisCover. Shear forces were applied to the samples with a universal testing machine, and bond strengths were measured in megapascals. The protective liquid polish (BisCover) layer did not affect bond strength. Blood contamination on acid-etched surfaces affects bond strength more than saliva contamination. When a protective liquid polish (BisCover) is applied to the tooth surface, the effect of contamination by blood or saliva is prevented.

Three-input gate logic circuits on chemically assembled single-electron transistors with organic and inorganic hybrid passivation layers

PubMed Central

Majima, Yutaka; Hackenberger, Guillaume; Azuma, Yasuo; Kano, Shinya; Matsuzaki, Kosuke; Susaki, Tomofumi; Sakamoto, Masanori; Teranishi, Toshiharu

2017-01-01

Abstract Single-electron transistors (SETs) are sub-10-nm scale electronic devices based on conductive Coulomb islands sandwiched between double-barrier tunneling barriers. Chemically assembled SETs with alkanethiol-protected Au nanoparticles show highly stable Coulomb diamonds and two-input logic operations. The combination of bottom-up and top-down processes used to form the passivation layer is vital for realizing multi-gate chemically assembled SET circuits, as this combination enables us to connect conventional complementary metal oxide semiconductor (CMOS) technologies via planar processes. Here, three-input gate exclusive-OR (XOR) logic operations are demonstrated in passivated chemically assembled SETs. The passivation layer is a hybrid bilayer of self-assembled monolayers (SAMs) and pulsed laser deposited (PLD) aluminum oxide (AlOx), and top-gate electrodes were prepared on the hybrid passivation layers. Top and two-side-gated SETs showed clear Coulomb oscillation and diamonds for each of the three available gates, and three-input gate XOR logic operation was clearly demonstrated. These results show the potential of chemically assembled SETs to work as logic devices with multi-gate inputs using organic and inorganic hybrid passivation layers. PMID:28634499

Three-input gate logic circuits on chemically assembled single-electron transistors with organic and inorganic hybrid passivation layers.

PubMed

Majima, Yutaka; Hackenberger, Guillaume; Azuma, Yasuo; Kano, Shinya; Matsuzaki, Kosuke; Susaki, Tomofumi; Sakamoto, Masanori; Teranishi, Toshiharu

2017-01-01

Single-electron transistors (SETs) are sub-10-nm scale electronic devices based on conductive Coulomb islands sandwiched between double-barrier tunneling barriers. Chemically assembled SETs with alkanethiol-protected Au nanoparticles show highly stable Coulomb diamonds and two-input logic operations. The combination of bottom-up and top-down processes used to form the passivation layer is vital for realizing multi-gate chemically assembled SET circuits, as this combination enables us to connect conventional complementary metal oxide semiconductor (CMOS) technologies via planar processes. Here, three-input gate exclusive-OR (XOR) logic operations are demonstrated in passivated chemically assembled SETs. The passivation layer is a hybrid bilayer of self-assembled monolayers (SAMs) and pulsed laser deposited (PLD) aluminum oxide (AlO[Formula: see text]), and top-gate electrodes were prepared on the hybrid passivation layers. Top and two-side-gated SETs showed clear Coulomb oscillation and diamonds for each of the three available gates, and three-input gate XOR logic operation was clearly demonstrated. These results show the potential of chemically assembled SETs to work as logic devices with multi-gate inputs using organic and inorganic hybrid passivation layers.

A Multi-Modal Face Recognition Method Using Complete Local Derivative Patterns and Depth Maps

PubMed Central

Yin, Shouyi; Dai, Xu; Ouyang, Peng; Liu, Leibo; Wei, Shaojun

2014-01-01

In this paper, we propose a multi-modal 2D + 3D face recognition method for a smart city application based on a Wireless Sensor Network (WSN) and various kinds of sensors. Depth maps are exploited for the 3D face representation. As for feature extraction, we propose a new feature called Complete Local Derivative Pattern (CLDP). It adopts the idea of layering and has four layers. In the whole system, we apply CLDP separately on Gabor features extracted from a 2D image and depth map. Then, we obtain two features: CLDP-Gabor and CLDP-Depth. The two features weighted by the corresponding coefficients are combined together in the decision level to compute the total classification distance. At last, the probe face is assigned the identity with the smallest classification distance. Extensive experiments are conducted on three different databases. The results demonstrate the robustness and superiority of the new approach. The experimental results also prove that the proposed multi-modal 2D + 3D method is superior to other multi-modal ones and CLDP performs better than other Local Binary Pattern (LBP) based features. PMID:25333290

Transparent Carbon Nanotube layers as cathodes in OLEDs

NASA Astrophysics Data System (ADS)

Papadimitratos, Alexios; Nasibulin, Albert; Kauppinen, Esko; Zakhidov, Anvar; Solarno Inc Collaboration; Aalto University Collaboration; UT Dallas Collaboration

2011-03-01

Organic Light Emitting diodes (OLEDs) have attracted high interest in recent years due to their potential use in future lighting and display applications. Reported work on OLEDs traditionally utilizes low work function materials as cathodes that are expensive to fabricate because of the high vacuum processing. Transparent carbon nanotube (CNT) sheets have excellent mechanical and electrical properties. We have already shown earlier that multi-wall (MWCNT) as well as single CNT (SWCNT) sheets can be used as effective anodes in bright OLEDs [,]. The true advantage of using the CNT sheets lies in flexible devices and new architectures with CNT sheet as layers in tandem devices with parallel connection. In this work, we are investigating the possibility of using SWCNT as cathodes in OLEDs. SWCNT sheets have been reported to show lower work function compared to MWCNT. Our work attempts to demonstrate transparent OLED devices with CNT anodes and cathodes. In the process, OLEDs with CNT cathodes have been fabricated in normal and inverted configurations using inorganic oxides (MoO3,ZnO) as invertion layers.

Improved efficiency in blue phosphorescent organic light-emitting diodes by the stepwise doping structure

NASA Astrophysics Data System (ADS)

Yang, Liping; Wang, Xiaoping; Kou, Zhiqi; Ji, Changyan

2017-04-01

The electro-optical properties of the blue phosphorescent organic light-emitting diodes (PHOLEDs) can be affected by the stepwise doping structure in the emitting layer (EML). A series of multi-EML devices with different doping concentration of blue dopant (FIrpic) are fabricated. The effect of the stepwise doping structure close to the electron transport layer is more obvious than that close to the hole transport layer. When the doping concentration increases gradually from the hole injection side to the electron injection side, the maximum values of the luminance, current and power efficiency can reach to 9745 cd/m2 (at 9 V), 32.0 cd/A and 25.1 lm/W in the device with the asymmetric tri-EML structure, which is improved by about 10% compared with that in the bi-EML device. When the number of the EML is four, the performance of the device becomes worse because of the interface effect resulting from different concentration of dopant.

Continuous blade coating for multi-layer large-area organic light-emitting diode and solar cell

NASA Astrophysics Data System (ADS)

Chen, Chun-Yu; Chang, Hao-Wen; Chang, Yu-Fan; Chang, Bo-Jie; Lin, Yuan-Sheng; Jian, Pei-Siou; Yeh, Han-Cheng; Chien, Hung-Ta; Chen, En-Chen; Chao, Yu-Chiang; Meng, Hsin-Fei; Zan, Hsiao-Wen; Lin, Hao-Wu; Horng, Sheng-Fu; Cheng, Yen-Ju; Yen, Feng-Wen; Lin, I.-Feng; Yang, Hsiu-Yuan; Huang, Kuo-Jui; Tseng, Mei-Rurng

2011-11-01

A continuous roll-to-roll compatible blade-coating method for multi-layers of general organic semiconductors is developed. Dissolution of the underlying film during coating is prevented by simultaneously applying heating from the bottom and gentle hot wind from the top. The solvent is immediately expelled and reflow inhibited. This method succeeds for polymers and small molecules. Uniformity is within 10% for 5 cm by 5 cm area with a mean value of tens of nanometers for both organic light-emitting diode (OLED) and solar cell structure with little material waste. For phosphorescent OLED 25 cd/A is achieved for green, 15 cd/A for orange, and 8 cd/A for blue. For fluorescent OLED 4.3 cd/A is achieved for blue, 9 cd/A for orange, and 6.9 cd/A for white. For OLED with 2 cm by 3 cm active area, the luminance variation is within 10%. Power conversion efficiency of 4.1% is achieved for polymer solar cell, similar to spin coating using the same materials. Very-low-cost and high-throughput fabrication of efficient organic devices is realized by the continuous blade-only method.

Thin coatings for protecting titanium aluminides in high-temperature oxidizing environments

NASA Technical Reports Server (NTRS)

Wiedemann, K. E.; Taylor, P. J.; Clark, R. K.; Wallace, T. A.

1991-01-01

Titanium aluminides have high specific strengths at high temperatures but are susceptible to environmental attack. Their use in many aerospace applications would require that they be protected with coatings that, for structural efficiency, must be thin. It is conceivable that acceptable coatings might be found in several oxide systems, and consequently, oxide coatings of many compositions were prepared from sol-gels for study. Response-surface methodology was used to refine coating compositions and factorial experiments were used to develop coating strategies. Oxygen permeability diagrams of two-layer coatings for several oxide systems, an analysis of multiple-layer coatings on rough and polished surfaces, and modeling of the oxidation weight gain are presented.

[Skin changes in albinism in persons of the Negroid race (light- and electron-microscopy studies].

PubMed

Semkin, V I; Mikhaĭlov, I N

1984-01-01

The skin of the negroid race albinos is studied light- and electron-microscopically. Morphological alterations, as compared to control, consist of the horny layer thickening, increase of the cellularity in the epidermis, appearance of numerous pronounced tonofibrillar-keratohyaline complexes in the granular cells and a well developed network of dense bundles of tonofibrils in the spinous layer. Melanocytes and Langerhans cells are similar by their structure and number to those in the control. The protein skeletons of melanosomes in keratinocytes and melanocytes are practically unchanged but they are completely deprived of melanine biopolymer. The dermal macrophages do not contain a melanin pigment. The morphological features of the albinos epidermis, particularly the horny layer thickening, increase of the cellularity and the presence of pronounced tonofibrillar-keratohyaline complexes represent most likely a compensatory protective mechanism against ultraviolet radiation.

The TiO2 Hierarchical Structure with Nanosheet Spheres for Improved Photoelectric Performance in Dye-Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Yin, Xin; Guan, Yingli; Song, Lixin; Xie, Xueyao; Du, Pingfan; Xiong, Jie

2018-04-01

A bi-layer photoanode is successfully fabricated for dye-sensitized solar cells (DSSCs) composed of P25/TiO2 nanorod (P25/TNR) as the underlayer and TiO2 nanosheet spheres (TNSs) as the light-scattering layer. Notably, the P25-TNR provides multiple functions, including more dye loading, more efficient charge transport and a lower electron recombination rate for the photoanode. Besides, the unique structure of TNS can significantly improve the light-harvesting capacity, boosting the light-harvesting efficiency. Therefore, an enhanced short-circuit current and power conversion efficiency of 18.04 mA cm-2 and 5.99%, respectively, were achieved for the P25/TNR-TNS-based DSSC, which was better than that of the P25-TNS-based (15.17 mA cm-2, 5.36%) and bare TNS-based (11.43 mA cm-2, 4.14%) DSSCs. This indicates that this bi-layer structure effectively combines the advantages of the one-dimensional (1D) nanostructure and three-dimensional (3D) hierarchical structure. In short, this work demonstrates the possibility of fabricating desirable photoanodes for high-performance DSSCs by rational design of nanostructures and effective combination of multi-functional components.

Optical Properties of Multi-Layered Insulation

NASA Technical Reports Server (NTRS)

Rodriguez, Heather M.; Abercromby, Kira J.; Barker, Edwin

2007-01-01

Multi-layer insulation, MLI, is a material used on rocket bodies and satellites mainly for thermal insulation. MLI can be comprised of a variety of materials, layer numbers, and dimensions based on its purpose. A common composition of MLI consists of outer facing copper-colored Kapton with an aluminized backing for the top and bottom layers and the middle consisting of alternating layers of DARCON or Nomex netting with aluminized Mylar. If this material became separated from the spacecraft or rocket body its orbit would vary greatly in eccentricity due to its high area to mass (A/m) and susceptibility to solar radiation pressure perturbations. Recently a debris population was found with high A/m, which could be MLI. Laboratory photometric measurements of one intact piece and three different layers of MLI is presented in an effort to predict the characteristics of a MLI light curve and aid in identifying the source of the new population. For this paper, the layers used will be consistent with the common MLI mentioned in the above paragraph. Using a robotic arm, the piece was rotated from 0-360 degrees in one degree increments along the object s longest axis. Laboratory photometric data was recorded with a CCD camera using various filters (Johnson B, Johnson V and Bessell R). The measurements were taken at an 18 degree (light-object-camera) phase angle. As expected, the MLI pieces showed characteristics similar to a bimodal magnitude plot of a flat plate, but with more photometric features, dependant upon the layer of MLI. Time exposures varied from piece to piece such that the amount of pixels saturated would be minimal. In addition to photometric laboratory measurements, laboratory spectral measurements are shown for the same MLI samples. Spectral data will be combined to match the wavelength region of photometric data so a measure of truth can be established for the photometric measurements. Spectral data shows a strong absorption feature near 4800 angstroms, which is due to the copper color of Kapton. If the debris is MLI and the outer layer of copper coloring of Kapton is present, evidence would be seen spectrally by the specific absorption feature as well as using R-B (red-blue) light curves. Using laboratory photometric measurements and the results from spectral laboratory measurements, an optical property database is provided for an object with a high A/m. The benefits of this database for remote optical measurements of orbital debris are shown by illustrating the optical properties expected for a high A/m object, specifically common satellite and rocket body MLI.

Interfacial layers evolution during annealing in Ti-Al multi-laminated composite processed using hot press and roll bonding

NASA Astrophysics Data System (ADS)

Assari, A. H.; Eghbali, B.

2016-09-01

Ti-Al multi-laminated composites have great potential in high strength and low weight structures. In the present study, tri-layer Ti-Al composite was synthesized by hot press bonding under 40 MPa at 570 °C for 1 h and subsequent hot roll bonding at about 450 °C. This process was conducted in two accumulative passes to 30% and to 67% thickness reduction in initial and final passes, respectively. Then, the final annealing treatments were done at 550, 600, 650, 700 and 750 °C for 2, 4 and 6 h. Investigations on microstructural evolution and thickening of interfacial layers were performed by scanning electron microscopes, energy dispersive spectrometer, X-ray diffraction and micro-hardness tests. The results showed that the thickening of diffusion layers corresponds to amount of deformation. In addition to thickening of the diffusion layers, the thickness of aluminum layers decreased and after annealing treatment at 750 °C for 6 h the aluminum layers were consumed entirely, which occurred because of the enhanced interdiffusion of Ti and Al elements. Scanning electron microscope equipped with energy dispersive spectrometer showed that the sequence of interfacial layers as Ti3Al-TiAl-TiAl2-TiAl3 which are believed to be the result of thermodynamic and kinetic of phase formation. Micro-hardness results presented the variation profile in accordance with the sequence of intermetallic phases and their different structures.

Testing the applicability of artificial intelligence techniques to the subject of erythemal ultraviolet solar radiation. Part two: an intelligent system based on multi-classifier technique.

PubMed

Elminir, Hamdy K; Own, Hala S; Azzam, Yosry A; Riad, A M

2008-03-28

The problem we address here describes the on-going research effort that takes place to shed light on the applicability of using artificial intelligence techniques to predict the local noon erythemal UV irradiance in the plain areas of Egypt. In light of this fact, we use the bootstrap aggregating (bagging) algorithm to improve the prediction accuracy reported by a multi-layer perceptron (MLP) network. The results showed that, the overall prediction accuracy for the MLP network was only 80.9%. When bagging algorithm is used, the accuracy reached 94.8%; an improvement of about 13.9% was achieved. These improvements demonstrate the efficiency of the bagging procedure, and may be used as a promising tool at least for the plain areas of Egypt.

A Solution Processed Flexible Nanocomposite Electrode with Efficient Light Extraction for Organic Light Emitting Diodes

NASA Astrophysics Data System (ADS)

Li, Lu; Liang, Jiajie; Chou, Shu-Yu; Zhu, Xiaodan; Niu, Xiaofan; Zhibinyu; Pei, Qibing

2014-03-01

Highly efficient organic light emitting diodes (OLEDs) based on multiple layers of vapor evaporated small molecules, indium tin oxide transparent electrode, and glass substrate have been extensively investigated and are being commercialized. The light extraction from the exciton radiative decay is limited to less than 30% due to plasmonic quenching on the metallic cathode and the waveguide in the multi-layer sandwich structure. Here we report a flexible nanocomposite electrode comprising single-walled carbon nanotubes and silver nanowires stacked and embedded in the surface of a polymer substrate. Nanoparticles of barium strontium titanate are dispersed within the substrate to enhance light extraction efficiency. Green polymer OLED (PLEDs) fabricated on the nanocomposite electrode exhibit a maximum current efficiency of 118 cd/A at 10,000 cd/m2 with the calculated external quantum efficiency being 38.9%. The efficiencies of white PLEDs are 46.7 cd/A and 30.5%, respectively. The devices can be bent to 3 mm radius repeatedly without significant loss of electroluminescent performance. The nanocomposite electrode could pave the way to high-efficiency flexible OLEDs with simplified device structure and low fabrication cost.

A solution processed flexible nanocomposite electrode with efficient light extraction for organic light emitting diodes.

PubMed

Li, Lu; Liang, Jiajie; Chou, Shu-Yu; Zhu, Xiaodan; Niu, Xiaofan; ZhibinYu; Pei, Qibing

2014-03-17

Highly efficient organic light emitting diodes (OLEDs) based on multiple layers of vapor evaporated small molecules, indium tin oxide transparent electrode, and glass substrate have been extensively investigated and are being commercialized. The light extraction from the exciton radiative decay is limited to less than 30% due to plasmonic quenching on the metallic cathode and the waveguide in the multi-layer sandwich structure. Here we report a flexible nanocomposite electrode comprising single-walled carbon nanotubes and silver nanowires stacked and embedded in the surface of a polymer substrate. Nanoparticles of barium strontium titanate are dispersed within the substrate to enhance light extraction efficiency. Green polymer OLED (PLEDs) fabricated on the nanocomposite electrode exhibit a maximum current efficiency of 118 cd/A at 10,000 cd/m(2) with the calculated external quantum efficiency being 38.9%. The efficiencies of white PLEDs are 46.7 cd/A and 30.5%, respectively. The devices can be bent to 3 mm radius repeatedly without significant loss of electroluminescent performance. The nanocomposite electrode could pave the way to high-efficiency flexible OLEDs with simplified device structure and low fabrication cost.

A Solution Processed Flexible Nanocomposite Electrode with Efficient Light Extraction for Organic Light Emitting Diodes

PubMed Central

Li, Lu; Liang, Jiajie; Chou, Shu-Yu; Zhu, Xiaodan; Niu, Xiaofan; ZhibinYu; Pei, Qibing

2014-01-01

Highly efficient organic light emitting diodes (OLEDs) based on multiple layers of vapor evaporated small molecules, indium tin oxide transparent electrode, and glass substrate have been extensively investigated and are being commercialized. The light extraction from the exciton radiative decay is limited to less than 30% due to plasmonic quenching on the metallic cathode and the waveguide in the multi-layer sandwich structure. Here we report a flexible nanocomposite electrode comprising single-walled carbon nanotubes and silver nanowires stacked and embedded in the surface of a polymer substrate. Nanoparticles of barium strontium titanate are dispersed within the substrate to enhance light extraction efficiency. Green polymer OLED (PLEDs) fabricated on the nanocomposite electrode exhibit a maximum current efficiency of 118 cd/A at 10,000 cd/m2 with the calculated external quantum efficiency being 38.9%. The efficiencies of white PLEDs are 46.7 cd/A and 30.5%, respectively. The devices can be bent to 3 mm radius repeatedly without significant loss of electroluminescent performance. The nanocomposite electrode could pave the way to high-efficiency flexible OLEDs with simplified device structure and low fabrication cost. PMID:24632742

Zinc Sulphide Overlayer Two-Dimensional Photonic Crystal for Enhanced Extraction of Light from a Micro Cavity Light-Emitting Diode

NASA Astrophysics Data System (ADS)

Mastro, Michael A.; Kim, Chul Soo; Kim, Mijin; Caldwell, Josh; Holm, Ron T.; Vurgaftman, Igor; Kim, Jihyun; Eddy, Charles R., Jr.; Meyer, Jerry R.

2008-10-01

A two-dimensional (2D) ZnS photonic crystal was deposited on the surface of a one-dimensional (1D) III-nitride micro cavity light-emitting diode (LED), to intermix the light extraction features of both structures (1D+2D). The deposition of an ideal micro-cavity optical thickness of ≈λ/2 is impractical for III-nitride LEDs, and in realistic multi-mode devices a large fraction of the light is lost to internal refraction as guided light. Therefore, a 2D photonic crystal on the surface of the LED was used to diffract and thus redirect this guided light out of the semiconductor over several hundred microns. Additionally, the employment of a post-epitaxy ZnS 2D photonic crystal avoided the typical etching into the GaN:Mg contact layer, a procedure which can cause damage to the near surface.

Multicast Routing and Wavelength Assignment with Shared Protection in Multi-Fiber WDM Mesh Networks: Optimal and Heuristic Solutions

NASA Astrophysics Data System (ADS)

Woradit, Kampol; Guyot, Matthieu; Vanichchanunt, Pisit; Saengudomlert, Poompat; Wuttisittikulkij, Lunchakorn

While the problem of multicast routing and wavelength assignment (MC-RWA) in optical wavelength division multiplexing (WDM) networks has been investigated, relatively few researchers have considered network survivability for multicasting. This paper provides an optimization framework to solve the MC-RWA problem in a multi-fiber WDM network that can recover from a single-link failure with shared protection. Using the light-tree (LT) concept to support multicast sessions, we consider two protection strategies that try to reduce service disruptions after a link failure. The first strategy, called light-tree reconfiguration (LTR) protection, computes a new multicast LT for each session affected by the failure. The second strategy, called optical branch reconfiguration (OBR) protection, tries to restore a logical connection between two adjacent multicast members disconnected by the failure. To solve the MC-RWA problem optimally, we propose an integer linear programming (ILP) formulation that minimizes the total number of fibers required for both working and backup traffic. The ILP formulation takes into account joint routing of working and backup traffic, the wavelength continuity constraint, and the limited splitting degree of multicast-capable optical cross-connects (MC-OXCs). After showing some numerical results for optimal solutions, we propose heuristic algorithms that reduce the computational complexity and make the problem solvable for large networks. Numerical results suggest that the proposed heuristic yields efficient solutions compared to optimal solutions obtained from exact optimization.

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

Xu, Hongyi; Li, Yang; Zeng, Danielle

Process integration and optimization is the key enabler of the Integrated Computational Materials Engineering (ICME) of carbon fiber composites. In this paper, automated workflows are developed for two types of composites: Sheet Molding Compounds (SMC) short fiber composites, and multi-layer unidirectional (UD) composites. For SMC, the proposed workflow integrates material processing simulation, microstructure representation volume element (RVE) models, material property prediction and structure preformation simulation to enable multiscale, multidisciplinary analysis and design. Processing parameters, microstructure parameters and vehicle subframe geometry parameters are defined as the design variables; the stiffness and weight of the structure are defined as the responses. Formore » multi-layer UD structure, this work focuses on the discussion of different design representation methods and their impacts on the optimization performance. Challenges in ICME process integration and optimization are also summarized and highlighted. Two case studies are conducted to demonstrate the integrated process and its application in optimization.« less

Multi-angle ZnO microstructures grown on Ag nanorods array for plasmon-enhanced near-UV-blue light emitter

NASA Astrophysics Data System (ADS)

Pal, Anil Kumar; Bharathi Mohan, D.

2017-10-01

Metal enhanced ultraviolet light emission has been explored in ZnO/Ag hybrid structures prepared by hydrothermal growth of multi-angled ZnO nanorods on slanted Ag nanorods array fabricated by the thermal evaporation technique. Slanted Ag nanorods are realized to be the stacking of non-spherical Ag nanoparticles, resulting in asymmetric surface plasmon resonance spectra. The surface roughness of Ag nanorod array films significantly influences the growth mechanism of ZnO nanorods, leading to the formation of multi-angled ZnO microflowers. ZnO/Ag hybrid structures facilitate the interfacial charge transfer from Ag to ZnO with the realization of negative shift in binding energy of Ag 3d orbitals by ˜0.8 eV. These high quality ZnO nanorods in ZnO/Ag hybrid nanostructures exhibit strong ultraviolet emission in the 383-396 nm region without broad deep level emission, which can be explained by a suitable band diagram. The metal enhanced photoluminescence is witnessed mainly due to interfacial charge transfer with its dependence on surface roughness of bottom layer Ag nanorods, number density of ZnO nanorods and diversity in the interfacial area between Ag and ZnO nanorods. The existence of strong ultraviolet light with minor blue light emission and appearance of CIE shade in strong violet-blue region by ZnO/Ag hybrid structures depict exciting possibilities towards near UV-blue light emitting devices.

Multi-angle ZnO microstructures grown on Ag nanorods array for plasmon-enhanced near-UV-blue light emitter.

PubMed

Pal, Anil Kumar; Mohan, D Bharathi

2017-10-13

Metal enhanced ultraviolet light emission has been explored in ZnO/Ag hybrid structures prepared by hydrothermal growth of multi-angled ZnO nanorods on slanted Ag nanorods array fabricated by the thermal evaporation technique. Slanted Ag nanorods are realized to be the stacking of non-spherical Ag nanoparticles, resulting in asymmetric surface plasmon resonance spectra. The surface roughness of Ag nanorod array films significantly influences the growth mechanism of ZnO nanorods, leading to the formation of multi-angled ZnO microflowers. ZnO/Ag hybrid structures facilitate the interfacial charge transfer from Ag to ZnO with the realization of negative shift in binding energy of Ag 3d orbitals by ∼0.8 eV. These high quality ZnO nanorods in ZnO/Ag hybrid nanostructures exhibit strong ultraviolet emission in the 383-396 nm region without broad deep level emission, which can be explained by a suitable band diagram. The metal enhanced photoluminescence is witnessed mainly due to interfacial charge transfer with its dependence on surface roughness of bottom layer Ag nanorods, number density of ZnO nanorods and diversity in the interfacial area between Ag and ZnO nanorods. The existence of strong ultraviolet light with minor blue light emission and appearance of CIE shade in strong violet-blue region by ZnO/Ag hybrid structures depict exciting possibilities towards near UV-blue light emitting devices.

The Study of Indicatrices of Space Object Coatings in a Controlled Laboratory Environment

NASA Astrophysics Data System (ADS)

Koshkin, N.; Burlak, N.; Petrov, M.; Strakhova, S.

The indicatrices of light scattering by radiation balance coatings used on space objects (SO) were determined in the laboratory experiment in a controlled condition. The laboratory device for the physical simulation of photometric observations of space objects in orbit, which was used in this case to study optical properties of coating samples, is described. The features of light reflection off plane coating samples, including multi-layer insulation (MLI) blankets, metal surfaces coated with several layers of enamel EP-140, special polyacrylate enamel AK-512 and matte finish Tp-CO-2, were determined. The indicated coatings are compound reflectors which exhibit both diffuse and specular reflections. The data obtained are to be used in the development of computer optical-geometric models of space objects or their fragments (space debris) to interpret the photometry results for real space objects.

Accelerating gradient improvement using shape-tailor laser front in radiation pressure acceleration progress

NASA Astrophysics Data System (ADS)

Wang, W. P.; Shen, B. F.; Xu, Z. Z.

2017-05-01

The accelerating gradient of a proton beam is crucial for stable radiation pressure acceleration (RPA) because the multi-dimensional instabilities increase γ times slower in the relativistic region. In this paper, a shape-tailored laser is proposed to significantly accelerate the ions in a controllable high accelerating gradient. In this method, the fastest ions initially rest in the middle of the foil are controlled to catch the compressed electron layer at the end of the hole-boring stage, thus the light-sail stage can start as soon as possible. Then the compressed electron layer is accelerated tightly together with the fastest ions by the shaped laser intensity, which further increases the accelerating gradient in the light-sail stage. Such tailored pulse may be beneficial for the RPA driven by the 10-fs 10 petawatt laser in the future.

Noncontact measurement of heart rate using facial video illuminated under natural light and signal weighted analysis.

PubMed

Yan, Yonggang; Ma, Xiang; Yao, Lifeng; Ouyang, Jianfei

2015-01-01

Non-contact and remote measurements of vital physical signals are important for reliable and comfortable physiological self-assessment. We presented a novel optical imaging-based method to measure the vital physical signals. Using a digital camera and ambient light, the cardiovascular pulse waves were extracted better from human color facial videos correctly. And the vital physiological parameters like heart rate were measured using a proposed signal-weighted analysis method. The measured HRs consistent with those measured simultaneously with reference technologies (r=0.94, p<0.001 for HR). The results show that the imaging-based method is suitable for measuring the physiological parameters, and provide a reliable and comfortable measurement mode. The study lays a physical foundation for measuring multi-physiological parameters of human noninvasively.

Protective Effect of Proanthocyanidins from Sea Buckthorn (Hippophae Rhamnoides L.) Seed against Visible Light-Induced Retinal Degeneration in Vivo.

PubMed

Wang, Yong; Zhao, Liang; Huo, Yazhen; Zhou, Feng; Wu, Wei; Lu, Feng; Yang, Xue; Guo, Xiaoxuan; Chen, Peng; Deng, Qianchun; Ji, Baoping

2016-05-02

Dietary proanthocyanidins (PACs) as health-protective agents have become an important area of human nutrition research because of their potent bioactivities. We investigated the retinoprotective effects of PACs from sea buckthorn (Hippophae rhamnoides L.) seed against visible light-induced retinal degeneration in vivo. Pigmented rabbits were orally administered sea buckthorn seed PACs (50 and 100 mg/kg/day) for 14 consecutive days of pre-illumination and seven consecutive days of post-illumination. Retinal function was quantified via electroretinography 7 days after light exposure. Retinal damage was evaluated by measuring the thickness of the full-thickness retina and outer nuclear layer 7 days after light exposure. Sea buckthorn seed PACs significantly attenuated the destruction of electroretinograms and maintained the retinal structure. Increased retinal photooxidative damage was expressed by the depletion of glutathione peroxidase and catalase activities, the decrease of total antioxidant capacity level and the increase of malondialdehyde level. Light exposure induced a significant increase of inflammatory cytokines (IL-1β, TNF-α and IL-6) and angiogenesis (VEGF) levels in retina. Light exposure upregulated the expression of pro-apoptotic proteins Bax and caspase-3 and downregulated the expression of anti-apoptotic protein Bcl-2. However, sea buckthorn seed PACs ameliorated these changes induced by light exposure. Sea buckthorn seed PACs mediated the protective effect against light-induced retinal degeneration via antioxidant, anti-inflammatory and antiapoptotic mechanisms.

Protective Effect of Proanthocyanidins from Sea Buckthorn (Hippophae Rhamnoides L.) Seed against Visible Light-Induced Retinal Degeneration in Vivo

PubMed Central

Wang, Yong; Zhao, Liang; Huo, Yazhen; Zhou, Feng; Wu, Wei; Lu, Feng; Yang, Xue; Guo, Xiaoxuan; Chen, Peng; Deng, Qianchun; Ji, Baoping

2016-01-01

Dietary proanthocyanidins (PACs) as health-protective agents have become an important area of human nutrition research because of their potent bioactivities. We investigated the retinoprotective effects of PACs from sea buckthorn (Hippophae rhamnoides L.) seed against visible light-induced retinal degeneration in vivo. Pigmented rabbits were orally administered sea buckthorn seed PACs (50 and 100 mg/kg/day) for 14 consecutive days of pre-illumination and seven consecutive days of post-illumination. Retinal function was quantified via electroretinography 7 days after light exposure. Retinal damage was evaluated by measuring the thickness of the full-thickness retina and outer nuclear layer 7 days after light exposure. Sea buckthorn seed PACs significantly attenuated the destruction of electroretinograms and maintained the retinal structure. Increased retinal photooxidative damage was expressed by the depletion of glutathione peroxidase and catalase activities, the decrease of total antioxidant capacity level and the increase of malondialdehyde level. Light exposure induced a significant increase of inflammatory cytokines (IL-1β, TNF-α and IL-6) and angiogenesis (VEGF) levels in retina. Light exposure upregulated the expression of pro-apoptotic proteins Bax and caspase-3 and downregulated the expression of anti-apoptotic protein Bcl-2. However, sea buckthorn seed PACs ameliorated these changes induced by light exposure. Sea buckthorn seed PACs mediated the protective effect against light-induced retinal degeneration via antioxidant, anti-inflammatory and antiapoptotic mechanisms. PMID:27144578

White light emitting diode based on InGaN chip with core/shell quantum dots

NASA Astrophysics Data System (ADS)

Shen, Changyu; Hong, Yan; Ma, Jiandong; Ming, Jiangzhou

2009-08-01

Quantum dots have many applications in optoelectronic device such as LEDs for its many superior properties resulting from the three-dimensional confinement effect of its carrier. In this paper, single chip white light-emitting diodes (WLEDs) were fabricated by combining blue InGaN chip with luminescent colloidal quantum dots (QDs). Two kinds of QDs of core/shell CdSe /ZnS and core/shell/shell CdSe /ZnS /CdS nanocrystals were synthesized by thermal deposition using cadmium oxide and selenium as precursors in a hot lauric acid and hexadecylamine trioctylphosphine oxide hybrid. This two kinds of QDs exhibited high photoluminescence efficiency with a quantum yield more than 41%, and size-tunable emission wavelengths from 500 to 620 nm. The QDs LED mainly consists of flip luminescent InGaN chip, glass ceramic protective coating, glisten cup, QDs using as the photoluminescence material, pyroceram, gold line, electric layer, dielectric layer, silicon gel and bottom layer for welding. The WLEDs had the CIE coordinates of (0.319, 0.32). The InGaN chip white-light-emitting diodes with quantum dots as the emitting layer are potentially useful in illumination and display applications.

Estimation of effective connectivity using multi-layer perceptron artificial neural network.

PubMed

Talebi, Nasibeh; Nasrabadi, Ali Motie; Mohammad-Rezazadeh, Iman

2018-02-01

Studies on interactions between brain regions estimate effective connectivity, (usually) based on the causality inferences made on the basis of temporal precedence. In this study, the causal relationship is modeled by a multi-layer perceptron feed-forward artificial neural network, because of the ANN's ability to generate appropriate input-output mapping and to learn from training examples without the need of detailed knowledge of the underlying system. At any time instant, the past samples of data are placed in the network input, and the subsequent values are predicted at its output. To estimate the strength of interactions, the measure of " Causality coefficient " is defined based on the network structure, the connecting weights and the parameters of hidden layer activation function. Simulation analysis demonstrates that the method, called "CREANN" (Causal Relationship Estimation by Artificial Neural Network), can estimate time-invariant and time-varying effective connectivity in terms of MVAR coefficients. The method shows robustness with respect to noise level of data. Furthermore, the estimations are not significantly influenced by the model order (considered time-lag), and the different initial conditions (initial random weights and parameters of the network). CREANN is also applied to EEG data collected during a memory recognition task. The results implicate that it can show changes in the information flow between brain regions, involving in the episodic memory retrieval process. These convincing results emphasize that CREANN can be used as an appropriate method to estimate the causal relationship among brain signals.

Thin Film Solar Cells: Organic, Inorganic and Hybrid

NASA Technical Reports Server (NTRS)

Dankovich, John

2004-01-01

Thin film solar cells are an important developing resource for hundreds of applications including space travel. In addition to being more cost effective than traditional single crystal silicon cells, thin film multi-crystaline cells are plastic and light weight. The plasticity of the cells allows for whole solar panels to be rolled out from reams. Organic layers are being investigated in order to increase the efficiency of the cells to create an organic / inorganic hybrid cell. The main focus of the group is a thin film inorganic cell made with the absorber CuInS2. So far the group has been successful in creating the layer from a single-source precursor. They also use a unique method of film deposition called chemical vapor deposition for this. The general makeup of the cell is a molybdenum back contact with the CuInS2 layer, then CdS, ZnO and aluminum top contacts. While working cells have been produced, the efficiency so far has been low. Along with quantum dot fabrication the side project of this that is currently being studied is adding a polymer layer to increase efficiency. The polymer that we are using is P3OT (Poly(3-octylthiopene-2,5-diyll), retroregular). Before (and if) it is added to the cell, it must be understood in itself. To do this simple diodes are being constructed to begin to look at its behavior. The P3OT is spin coated onto indium tin oxide and silver or aluminum contacts are added. This method is being studied in order to find the optimal thickness of the layer as well as other important considerations that may later affect the composition of the finished solar cell. Because the sun is the most abundant renewable, energy source that we have, it is important to learn how to harness that energy and begin to move away from our other depleted non-renewable energy sources. While traditional silicon cells currently create electricity at relatively high efficiencies, they have drawbacks such as weight and rigidness that make them unattractive especially for space applications. Thin film photovoltaics have the potential to alleviate these problems and create a cheap and efficient way to harness the power of the sun.

Dense modifiable interconnections utilizing photorefractive volume holograms

NASA Astrophysics Data System (ADS)

Psaltis, Demetri; Qiao, Yong

1990-11-01

This report describes an experimental two-layer optical neural network built at Caltech. The system uses photorefractive volume holograms to implement dense, modifiable synaptic interconnections and liquid crystal light valves (LCVS) to perform nonlinear thresholding operations. Kanerva's Sparse, Distributed Memory was implemented using this network and its ability to recognize handwritten character-alphabet (A-Z) has been demonstrated experimentally. According to Kanerva's model, the first layer has fixed, random weights of interconnections and the second layer is trained by sum-of-outer-products rule. After training, the recognition rates of the network on the training set (104 patterns) and test set (520 patterns) are 100 and 50 percent, respectively.

Multi-layered chalcogenides with potential for magnetism and superconductivity

DOE PAGES

Li, Li; Parker, David S.; dela Cruz, Clarina R.; ...

2016-10-24

Layered thallium copper chalcogenides can form single, double, or triple layers of Cu– Ch separated by Tl sheets. Here we report on the preparation and properties of Tl-based materials of TlCu 2Se 2, TlCu 4S 3, TlCu 4Se 3 and TlCu 6S 4. Having no long-range magnetism for these materials is quite surprising considering the possibilities of inter- and intra-layer exchange interactions through Cu 3 d, and we measure by magnetic susceptibility and confirm by neutron diffraction. First principles density-functional theory calculations for both the single-layer TlCu 2Se 2 (isostructural to the ‘122’ iron-based superconductors) and the double-layer TlCu 4Semore » 3 suggest a lack of Fermi-level spectral weight that is needed to drive a magnetic or superconducting instability. Furthermore, for multiple structural layers with Fe, there is much greater likelihood for magnetism and superconductivity.« less

Controllable liquid colour-changing lenses with microfluidic channels for vision protection, camouflage and optical filtering based on soft lithography fabrication.

PubMed

Zhang, Min; Li, Songjing

2016-01-01

In this work, liquid colour-changing lenses for vision protection, camouflage and optical filtering are developed by circulating colour liquids through microfluidic channels on the lenses manually. Soft lithography technology is applied to fabricate the silicone liquid colour-changing layers with microfluidic channels on the lenses instead of mechanical machining. To increase the hardness and abrasion resistance of the silicone colour-changing layers on the lenses, proper fabrication parameters such as 6:1 (mass ration) mixing proportion and 100 °C curing temperature for 2 h are approved for better soft lithography process of the lenses. Meanwhile, a new surface treatment for the irreversible bonding of silicone colour-changing layer with optical resin (CR39) substrate lens by using 5 % (volume ratio) 3-Aminopropyltriethoxysilane solution is proposed. Vision protection, camouflage and optical filtering functions of the lenses are investigated with different designs of the channels and multi-layer structures. Each application can not only well achieve their functional demands, but also shows the advantages of functional flexibility, rapid prototyping and good controllability compared with traditional ways. Besides optometry, some other designs and applications of the lenses are proposed for potential utility in the future.

Modal Identification in an Automotive Multi-Component System Using HS 3D-DIC

PubMed Central

López-Alba, Elías; Felipe-Sesé, Luis; Díaz, Francisco A.

2018-01-01

The modal characterization of automotive lighting systems becomes difficult using sensors due to the light weight of the elements which compose the component as well as the intricate access to allocate them. In experimental modal analysis, high speed 3D digital image correlation (HS 3D-DIC) is attracting the attention since it provides full-field contactless measurements of 3D displacements as main advantage over other techniques. Different methodologies have been published that perform modal identification, i.e., natural frequencies, damping ratios, and mode shapes using the full-field information. In this work, experimental modal analysis has been performed in a multi-component automotive lighting system using HS 3D-DIC. Base motion excitation was applied to simulate operating conditions. A recently validated methodology has been employed for modal identification using transmissibility functions, i.e., the transfer functions from base motion tests. Results make it possible to identify local and global behavior of the different elements of injected polymeric and metallic materials. PMID:29401725

Pressurized Lunar Rover (PLR)

NASA Technical Reports Server (NTRS)

Creel, Kenneth; Frampton, Jeffrey; Honaker, David; Mcclure, Kerry; Zeinali, Mazyar; Bhardwaj, Manoj; Bulsara, Vatsal; Kokan, David; Shariff, Shaun; Svarverud, Eric

1992-01-01

The objective of this project was to design a manned pressurized lunar rover (PLR) for long-range transportation and for exploration of the lunar surface. The vehicle must be capable of operating on a 14-day mission, traveling within a radius of 500 km during a lunar day or within a 50-km radius during a lunar night. The vehicle must accommodate a nominal crew of four, support two 28-hour EVA's, and in case of emergency, support a crew of six when near the lunar base. A nominal speed of ten km/hr and capability of towing a trailer with a mass of two mt are required. Two preliminary designs have been developed by two independent student teams. The PLR 1 design proposes a seven meter long cylindrical main vehicle and a trailer which houses the power and heat rejection systems. The main vehicle carries the astronauts, life support systems, navigation and communication systems, lighting, robotic arms, tools, and equipment for exploratory experiments. The rover uses a simple mobility system with six wheels on the main vehicle and two on the trailer. The nonpressurized trailer contains a modular radioisotope thermoelectric generator (RTG) supplying 6.5 kW continuous power. A secondary energy storage for short-term peak power needs is provided by a bank of lithium-sulfur dioxide batteries. The life support system is partly a regenerative system with air and hygiene water being recycled. A layer of water inside the composite shell surrounds the command center allowing the center to be used as a safe haven during solar flares. The PLR 1 has a total mass of 6197 kg. It has a top speed of 18 km/hr and is capable of towing three metric tons, in addition to the RTG trailer. The PLR 2 configuration consists of two four-meter diameter, cylindrical hulls which are passively connected by a flexible passageway, resulting in the overall vehicle length of 11 m. The vehicle is driven by eight independently suspended wheels. The dual-cylinder concept allows articulated as well as double Ackermann steering. The primary power of 8 kW is supplied by a dynamic isotope system using a closed Brayton cycle with a xenon-hydrogen mixture as the working fluid. A sodium-sulfur battery serves as the secondary power source. Excess heat produced by the primary power system and other rover systems is rejected by radiators located on the top of the rear cylinder. The total mass of the PLR 2 is 7015 kg. Simplicity and low total weight have been the driving principles behind the design of PLR 1. The overall configuration consists of a 7-m-long, 3-m-diameter cylindrical main vehicle and a two-wheeled trailer. The cylinder of the main body is capped by eight-section, faceted, semi-hemispherical ends. The trailer contains the RTG power source and is not pressurized. The shell of the main body is constructed of a layered carbon fiber/foam/Kevlar sandwich structure. Included in the shell is a layer of water for radiation protection. The layer of water extends from the front of the rover over the crew compartment and creates a safe haven for the crew during a solar flare-up. The carbon fiber provides the majority of the strength and stiffness and the Kevlar provides protection from micrometeoroids. The Kevlar is covered with a gold foil and multi-layer insulation (MLI) to reduce radiation degradation and heat transfer through the wall. A thin thermoplastic layer seals the fiber and provides additional strength.

Pressurized Lunar Rover (PLR)

NASA Astrophysics Data System (ADS)

Creel, Kenneth; Frampton, Jeffrey; Honaker, David; McClure, Kerry; Zeinali, Mazyar; Bhardwaj, Manoj; Bulsara, Vatsal; Kokan, David; Shariff, Shaun; Svarverud, Eric

The objective of this project was to design a manned pressurized lunar rover (PLR) for long-range transportation and for exploration of the lunar surface. The vehicle must be capable of operating on a 14-day mission, traveling within a radius of 500 km during a lunar day or within a 50-km radius during a lunar night. The vehicle must accommodate a nominal crew of four, support two 28-hour EVA's, and in case of emergency, support a crew of six when near the lunar base. A nominal speed of ten km/hr and capability of towing a trailer with a mass of two mt are required. Two preliminary designs have been developed by two independent student teams. The PLR 1 design proposes a seven meter long cylindrical main vehicle and a trailer which houses the power and heat rejection systems. The main vehicle carries the astronauts, life support systems, navigation and communication systems, lighting, robotic arms, tools, and equipment for exploratory experiments. The rover uses a simple mobility system with six wheels on the main vehicle and two on the trailer. The nonpressurized trailer contains a modular radioisotope thermoelectric generator (RTG) supplying 6.5 kW continuous power. A secondary energy storage for short-term peak power needs is provided by a bank of lithium-sulfur dioxide batteries. The life support system is partly a regenerative system with air and hygiene water being recycled. A layer of water inside the composite shell surrounds the command center allowing the center to be used as a safe haven during solar flares. The PLR 1 has a total mass of 6197 kg. It has a top speed of 18 km/hr and is capable of towing three metric tons, in addition to the RTG trailer. The PLR 2 configuration consists of two four-meter diameter, cylindrical hulls which are passively connected by a flexible passageway, resulting in the overall vehicle length of 11 m. The vehicle is driven by eight independently suspended wheels. The dual-cylinder concept allows articulated as well as double Ackermann steering. The primary power of 8 kW is supplied by a dynamic isotope system using a closed Brayton cycle with a xenon-hydrogen mixture as the working fluid.

Novel multichannel surface plasmon resonance photonic crystal fiber biosensor

NASA Astrophysics Data System (ADS)

Hameed, Mohamed Farhat O.; Alrayk, Yassmin K. A.; Shaalan, A. A.; El Deeb, Walid S.; Obayya, S. S. A.

2016-04-01

In this paper, a novel design of highly sensitive biosensor based on photonic crystal fiber is presented and analyzed using full vectorial finite element method. The suggested design depends on using silver layer as a plasmonic active material coated by a gold layer to protect silver oxidation. The reported sensor is based on the detection using the quasi transverse electric (TE) and quasi transverse magnetic (TM) modes which offers the possibility of multi-channel/multi-analyte sensing. The sensor geometrical parameters are optimized to achieve high sensitivity for the two polarized modes. High refractive index sensitivity of about 4750 nm/RIU (refractive index unit) and 4300 nm/RIU with corresponding resolutions of 2.1×10-5 RIU, and 2.33×10-5 RIU can be obtained for the quasi TM and quasi TE modes, respectively.

HST Multi Layer Insulation Failure Review Board Findings

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline; Hansen, Patricia

1998-01-01

The mechanical and optical properties of the thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Astronaut observations and photographs from the Second Servicing Mission (SM2) revealed large cracks in the metallized Teflon fluorinated ethylene propylene (FEP), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. Also, the absorptance of the bonded metallized Teflon FEP radiator surfaces of the telescope has increased over time. A Failure Review Board was established to determine the damage mechanism and to identify a replacement material. Samples of the top layer of the MLI and radiator material were retrieved during SM2, and a thorough investigation into the degradation followed in order to determine the primary cause of the damage. Mapping of the cracks on HST and the ground testing showed that thermal cycling with deep-layer damage from electron and proton radiation are necessary to cause the observed embrittlement. Further, strong evidence was found indicating that chain scission (reduced molecular weight) is the dominant form of damage to the metallized Teflon FEP. Given the damage to the outer layer of the multi-layer insulation (MLI) that was apparent during the second servicing mission (SM2), the decision was made to replace the outer layer during subsequent servicing missions. The replacement material had to meet the stringent thermal requirements of the spacecraft and maintain structural integrity for at least ten years. Ten candidate materials were exposed to simulated orbital environments and a replacement material was selected. This presentation will summarize the FRB results, in particular, the analysis of the retrieved specimens, the results of the simulated environmental exposures, and the selection of the replacement material. The NASA Space Environments and Effects community needs to hear these results because they reveal that Teflon (FEP) films should not be used in LEO as routinely as they are today.

Hard and flexible optical printed circuit board

NASA Astrophysics Data System (ADS)

Lee, El-Hang; Lee, Hyun Sik; Lee, S. G.; O, B. H.; Park, S. G.; Kim, K. H.

2007-02-01

We report on the design and fabrication of hard and flexible optical printed circuit boards (O-PCBs). The objective is to realize generic and application-specific O-PCBs, either in hard form or flexible form, that are compact, light-weight, low-energy, high-speed, intelligent, and environmentally friendly, for low-cost and high-volume universal applications. The O-PCBs consist of 2-dimensional planar arrays of micro/nano-scale optical wires, circuits and devices that are interconnected and integrated to perform the functions of sensing, storing, transporting, processing, switching, routing and distributing optical signals on flat modular boards. For fabrication, the polymer and organic optical wires and waveguides are first fabricated on a board and are used to interconnect and integrate micro/nano-scale photonic devices. The micro/nano-optical functional devices include lasers, detectors, switches, sensors, directional couplers, multi-mode interference devices, ring-resonators, photonic crystal devices, plasmonic devices, and quantum devices. For flexible boards, the optical waveguide arrays are fabricated on flexible poly-ethylen terephthalate (PET) substrates by UV embossing. Electrical layer carrying VCSEL and PD array is laminated with the optical layer carrying waveguide arrays. Both hard and flexible electrical lines are replaced with high speed optical interconnection between chips over four waveguide channels up to 10Gbps on each. We discuss uses of hard or flexible O-PCBs for telecommunication systems, computer systems, transportation systems, space/avionic systems, and bio-sensor systems.

Polyimide/Carbon Nanotube Composite Films for Electrostatic Charge Mitigation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Delozier, Donavon M.; Connell, John W.; Watson, Kent A.

2004-01-01

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge (ESC) build-up have potential applications on large, deployable, ultra-light weight Gossamer spacecraft as thin film membranes on antennas, solar sails, thermal/optical coatings, multi-layer insulation blankets, etc.. The challenge has been to develop a method to impart robust electrical conductivity into these materials without increasing solar absorptivity (alpha ) or decreasing optical transparency or film flexibility. Since these spacecraft will require significant compaction prior to launch, the film portion of the spacecraft will require folding. The state-of-the-art clear, conductive coating (e.g. indium-tin-oxide, ITO) is brittle and cannot tolerate folding. In this report, doping a polymer with single-walled carbon nanotubes (SWNTs) using two different methods afforded materials with good flexibility and surface conductivities in the range sufficient for ESC mitigation. A coating method afforded materials with minimal effects on the mechanical, optical, and thermo-optical properties as compared to dispersal of SWNTs in the matrix. The chemistry and physical properties of these nanocomposites are discussed.

Fiber-optically sensorized composite wing

NASA Astrophysics Data System (ADS)

Costa, Joannes M.; Black, Richard J.; Moslehi, Behzad; Oblea, Levy; Patel, Rona; Sotoudeh, Vahid; Abouzeida, Essam; Quinones, Vladimir; Gowayed, Yasser; Soobramaney, Paul; Flowers, George

2014-04-01

Electromagnetic interference (EMI) immune and light-weight, fiber-optic sensor based Structural Health Monitoring (SHM) will find increasing application in aerospace structures ranging from aircraft wings to jet engine vanes. Intelligent Fiber Optic Systems Corporation (IFOS) has been developing multi-functional fiber Bragg grating (FBG) sensor systems including parallel processing FBG interrogators combined with advanced signal processing for SHM, structural state sensing and load monitoring applications. This paper reports work with Auburn University on embedding and testing FBG sensor arrays in a quarter scale model of a T38 composite wing. The wing was designed and manufactured using fabric reinforced polymer matrix composites. FBG sensors were embedded under the top layer of the composite. Their positions were chosen based on strain maps determined by finite element analysis. Static and dynamic testing confirmed expected response from the FBGs. The demonstrated technology has the potential to be further developed into an autonomous onboard system to perform load monitoring, SHM and Non-Destructive Evaluation (NDE) of composite aerospace structures (wings and rotorcraft blades). This platform technology could also be applied to flight testing of morphing and aero-elastic control surfaces.

Silicon pixel R&D for CLIC

NASA Astrophysics Data System (ADS)

Munker, M.

2017-01-01

Challenging detector requirements are imposed by the physics goals at the future multi-TeV e+ e- Compact Linear Collider (CLIC). A single point resolution of 3 μm for the vertex detector and 7 μm for the tracker is required. Moreover, the CLIC vertex detector and tracker need to be extremely light weighted with a material budget of 0.2% X0 per layer in the vertex detector and 1-2% X0 in the tracker. A fast time slicing of 10 ns is further required to suppress background from beam-beam interactions. A wide range of sensor and readout ASIC technologies are investigated within the CLIC silicon pixel R&D effort. Various hybrid planar sensor assemblies with a pixel size of 25×25 μm2 and 55×55 μm2 have been produced and characterised by laboratory measurements and during test-beam campaigns. Experimental and simulation results for thin (50 μm-500 μm) slim edge and active-edge planar, and High-Voltage CMOS sensors hybridised to various readout ASICs (Timepix, Timepix3, CLICpix) are presented.

Preparation and properties of the multi-layer aerogel thermal insulation composites

NASA Astrophysics Data System (ADS)

Wang, Miao; Feng, Junzong; Jiang, Yonggang; Zhang, Zhongming; Feng, Jian

2018-03-01

Multi-layer insulation materials possess low radiation thermal conductivity, and excellent thermal insulation property in a vacuum environment. However, the spacers of the traditional multi-layer insulation materials are mostly loose fibers, which lead to more sensitive to the vacuum environmental of serviced. With the vacuum degree declining, gas phases thermal convection increase obviously, and the reflective screen will be severe oxidation, all of these make the thermal insulation property of traditional multi-layer insulation deteriorate, thus limits its application scope. In this paper, traditional multi-layer insulation material is combined with aerogel and obtain a new multi-layer aerogel thermal insulation composite, and the effects of the number, thickness and type of the reflective screens on the thermal insulation properties of the multi-layer composites are also studied. The result is that the thermal insulation property of the new type multi-layer aerogel composites is better than the pure aerogel composites and the traditional multi-layer insulation composites. When the 0.01 mm stainless steel foil as the reflective screen, and the aluminum silicate fiber and silica aerogel as the spacer layer, the layer density of composite with the best thermal insulation property is one layer per millimeter at 1000 °C.

Establishing Dual Electrogenerated Chemiluminescence and Multi-Color Electrochromism in Functional Ionic Transition Metal Complexes

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

Puodziukynaite, Egle; Oberst, Justin L.; Dyer, Aubrey L.

A combination of electrochromism and electroluminescence in functional materials could lead to single-layer dual electrochromic/electroluminescent (EC/EL) display devices, capable of simultaneous operation in emissive and reflective modes. Whereas such next generation displays could provide optimal visibility in any ambient lighting situation, materials available that exhibit such characteristics in the active layer are limited due to the required intrinsic multifunctionality (i.e., redox activity, electroluminescence, electrochromism, and ion conductivity) and to date can only be achieved via the rational design of ionic transition-metal complexes. Reported herein is the synthesis and characterization of a new family of acrylate-containing ruthenium (tris)bipyridine-based coordination complexes withmore » multifunctional characteristics. Potential use of the presented compounds in EC/EL devices is established, as they are applied as cross-linked electrochromic films and electrochemiluminescent layers in light-emitting electrochemical cell devices. Electrochromic switching of the polymeric networks between yellow, orange, green, brown and transmissive states is demonstrated, and electrochemiluminescent devices based on the complexes synthesized show red-orange to deep red emission with λ{sub max} ranging from 680 to 722 nm and luminance up to 135 cd/m{sup 2}. Additionally, a dual EC/EL device prototype is presented where light emission and multicolor electrochromism occur from the same pixel comprised of a single active layer, demonstrating a true combination of these properties in ionic transition-metal complexes.« less

On the properties of organic heterostructures prepared with nano-patterned metallic electrode

NASA Astrophysics Data System (ADS)

Breazu, C.; Socol, M.; Preda, N.; Matei, E.; Rasoga, O.; Girtan, M.; Mallet, R.; Stanculescu, F.; Stanculescu, A.

2018-06-01

This paper presents a comparative study between the properties of the heterostructures realized with single/multi layer organic (zinc phthalocyanine or/and fullerene) prepared on Si substrate between flat or patterned aluminum (Al) layer metallic electrode and multi layer ZnO/Au/ZnO transparent conductor electrode (TCE). The UV-Nanoimprint Lithography was used for the realization of a 2D array of nanostructures (holes/pillars) characterized by a periodicity of 1.1 μm and cylindrical shape: diameter = 400 nm and depth/height = 300 nm. The effect of the electrode patterning on the properties of the organic heterostructures was analyzed. For the samples with patterned Al electrode was remarked a slight red shift of the peaks in the reflection spectra determined by an increased interaction between the organic molecules in the delimited region of the patterned holes. The shape of the emission spectra at excitation with UV light showed a narrow intense peak around 500 nm associated with the intense resonance phenomena between the energy of the incident light and the surface plasmons in the patterned Al layer. The TCE followed the morphology of the organic film on which it was deposited. The significant differences between the morphology of the top layer in the heterostructures realized on flat and patterned Al are correlated with the total thickness of the successively deposited layers and with the particularities of the molecular arrangement, leading to the preservation or deleting of patterning. An injection contact behavior was evidence for most heterostructures built on flat and patterned Al. The slight increase in current at an applied bias <1 V in the heterostructure Si/Al/ZnPc/TCE is attributed to the larger interfacial area between the patterned Al electrode and ZnPc layer compared to the interface area between flat Al and ZnPc. A buffer layer of 1,4,5,8-naphthalen-tetracarboxylic dianhydride (NTCDA), sandwiched between the flat metallic electrode and organic film in the heterostructure Si/Al/C60/ZnPc/TCE has determined an increase in the current at low applied voltages.

Interface and thickness tuning for blade coated small-molecule organic light-emitting diodes with high power efficiency

NASA Astrophysics Data System (ADS)

Chang, Yu-Fan; Chiu, Yu-Chian; Chang, Hao-Wen; Wang, Yi-Siang; Shih, Yi-Lun; Wu, Chih-Hao; Liu, Yi-Lun; Lin, Yu-Sheng; Meng, Hsin-Fei; Chi, Yun; Huang, Heh-Lung; Tseng, Mei-Rurng; Lin, Hao-Wu; Zan, Hsiao-Wen; Horng, Sheng-Fu; Juang, Jenh-Yih

2013-09-01

We developed a general method based on fluorescence microscopy to characterize the interface dissolution in multi-layer organic light-emitting diodes (OLEDs) by blade coating. A sharp bi-layer edge was created before blade coating, with the bottom layer being insoluble and top layer soluble. After blade coating, fluorescence images showed that the edge of the top layer shifted when the layer dissolved completely, whereas the bottom layer's edge remained in place as a positioning mark. The dissolution depth was determined to be 15-20 nm when the emissive-layer host of 2,6-bis (3-(9H-carbazol-9-yl)phenyl) pyridine (26DCzPPy) was coated on the hole-transport layer of N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine(NPB), which was consistent with a sudden drop in efficiency of orange OLEDs with layer thickness below 20 nm. Thus, the layer thickness of OLEDs was optimized to stay more than 20 nm for blade coating. For a two-color white OLED with the structure TCTA/26DCzPPy:PO-01-TB:FIrpic/TPBI, efficiency was 24 cd/A and 8.5 lm/W at 1000 cd/m2. For a three-color white OLED with Os(fptz)2(dhpm) added as the emitter, the efficiency was 12.3 cd/A and 3.7 lm/W at 1000 cd/m2. For a green device with the structure TCTA/26DCzPPy:Ir(mppy)3/TPBI, the efficiency was 41.9 cd/A and 23.4 lm/W at 1000 cd/m2.

Optimization of antireflection coating design for multijunction solar cells and concentrator systems

NASA Astrophysics Data System (ADS)

Valdivia, Christopher E.; Desfonds, Eric; Masson, Denis; Fafard, Simon; Carlson, Andrew; Cook, John; Hall, Trevor J.; Hinzer, Karin

2008-06-01

Photovoltaic solar cells are a route towards local, environmentally benign, sustainable and affordable energy solutions. Antireflection coatings are necessary to input a high percentage of available light for photovoltaic conversion, and therefore have been widely exploited for silicon solar cells. Multi-junction III-V semiconductor solar cells have achieved the highest efficiencies of any photovoltaic technology, yielding up to 40% in the laboratory and 37% in commercial devices under varying levels of concentrated light. These devices benefit from a wide absorption spectrum (300- 1800 nm), but this also introduces significant challenges for antireflection coating design. Each sub-cell junction is electrically connected in series, limiting the overall device photocurrent by the lowest current-producing junction. Therefore, antireflection coating optimization must maximize the current from the limiting sub-cells at the expense of the others. Solar concentration, necessary for economical terrestrial deployment of multi-junction solar cells, introduces an angular-dependent irradiance spectrum. Antireflection coatings are optimized for both direct normal incidence in air and angular incidence in an Opel Mk-I concentrator, resulting in as little as 1-2% loss in photocurrent as compared to an ideal zero-reflectance solar cell, showing a similar performance to antireflection coatings on silicon solar cells. A transparent conductive oxide layer has also been considered to replace the metallic-grid front electrode and for inclusion as part of a multi-layer antireflection coating. Optimization of the solar cell, antireflection coating, and concentrator system should be considered simultaneously to enable overall optimal device performance.

Correlation between molten vanadium salts and the structural degradation of HK-type steel superheater tubes

NASA Astrophysics Data System (ADS)

de Carvalho Nunes, Frederico; de Almeida, Luiz Henrique; Ribeiro, André Freitas

2006-12-01

HK steels are among the most used heat-resistant cast stainless steels, being corrosion-resistant and showing good mechanical properties at high service temperatures. These steels are widely used in reformer furnaces and as superheater tubes. During service, combustion gases leaving the burners come in contact with these tubes, resulting in corrosive attack and a large weight loss occurs due to the presence of vanadium, which forms low melting point salts, removing the protective oxide layer. In this work the external surface of a tube with dramatic wall thickness reduction was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The identification of the phases was achieved by energy dispersive spectroscopy (EDS) analyses. The results showed oxides arising from the external surface. In this oxidized region vanadium compounds inside chromium carbide particles were also observed, due to inward vanadium diffusion during corrosion attack. A chemical reaction was proposed to explain the presence of vanadium in the metal microstructure.

Polarimetry of nacre in iridescent shells

NASA Astrophysics Data System (ADS)

Metzler, R. A.; Burgess, C.; Regan, B.; Spano, S.; Galvez, E. J.

2014-09-01

We investigate the light transmitted or reflected from nacre (mother of pearl) taken from the iridescent shell of the bivalve Pinctad a fucata. These nacre surfaces have a rich structure, composed of aragonite crystals arranged as tablets or bricks, 5 μm wide and 400-500 nm thick, surrounded by 30nm thick organic mortar. The light reflected from these shell surfaces, or transmitted through thin polished layers, is rich in its polarization content, exhibiting a space dependent variation in the state of polarization with a high density of polarization singularities. Our goal is to use the polarization information to infer the structure of the biominerals and the role of the organic layer in determining the orientation of the crystals. In the experiments we send the light from a laser with a uniform state of polarization onto the shell, and analyze the light that is either transmitted or reflected, depending on the type of experiment, imaging it after its passage through polarization filters. We use the images from distinct filters to obtain the Stokes parameters, and hence the state of polarization, of each image point. We also construct the Mueller matrix for each imaged point, via 36 measurements. We do this for distinct physical and chemical treatments of the shell sample. Preliminary data shows that the organic layer may be responsible for organizing a multi-crystalline arrangement of aragonite tablets.

Segmented ceramic liner for induction furnaces

DOEpatents

Gorin, Andrew H.; Holcombe, Cressie E.

1994-01-01

A non-fibrous ceramic liner for induction furnaces is provided by vertically stackable ring-shaped liner segments made of ceramic material in a light-weight cellular form. The liner segments can each be fabricated as a single unit or from a plurality of arcuate segments joined together by an interlocking mechanism. Also, the liner segments can be formed of a single ceramic material or can be constructed of multiple concentric layers with the layers being of different ceramic materials and/or cellular forms. Thermomechanically damaged liner segments are selectively replaceable in the furnace.

Segmented ceramic liner for induction furnaces

DOEpatents

Gorin, A.H.; Holcombe, C.E.

1994-07-26

A non-fibrous ceramic liner for induction furnaces is provided by vertically stackable ring-shaped liner segments made of ceramic material in a light-weight cellular form. The liner segments can each be fabricated as a single unit or from a plurality of arcuate segments joined together by an interlocking mechanism. Also, the liner segments can be formed of a single ceramic material or can be constructed of multiple concentric layers with the layers being of different ceramic materials and/or cellular forms. Thermomechanically damaged liner segments are selectively replaceable in the furnace. 5 figs.

A siphonous morphology affects light-harvesting modulation in the intertidal green macroalga Bryopsis corticulans (Ulvophyceae).

PubMed

Giovagnetti, Vasco; Han, Guangye; Ware, Maxwell A; Ungerer, Petra; Qin, Xiaochun; Wang, Wen-Da; Kuang, Tingyun; Shen, Jian-Ren; Ruban, Alexander V

2018-06-01

The macroalga Bryopsis corticulans relies on a sustained protective NPQ and a peculiar body architecture to efficiently adapt to the extreme light changes of intertidal shores. During low tides, intertidal algae experience prolonged high light stress. Efficient dissipation of excess light energy, measured as non-photochemical quenching (NPQ) of chlorophyll fluorescence, is therefore required to avoid photodamage. Light-harvesting regulation was studied in the intertidal macroalga Bryopsis corticulans, during high light and air exposure. Photosynthetic capacity and NPQ kinetics were assessed in different filament layers of the algal tufts and in intact chloroplasts to unravel the nature of NPQ in this siphonous green alga. We found that the morphology and pigment composition of the B. corticulans body provides functional segregation between surface sunlit filaments (protective state) and those that are underneath and undergo severe light attenuation (light-harvesting state). In the surface filaments, very high and sustained NPQ gradually formed. NPQ induction was triggered by the formation of transthylakoid proton gradient and independent of the xanthophyll cycle. PsbS and LHCSR proteins seem not to be active in the NPQ mechanism activated by this alga. Our results show that B. corticulans endures excess light energy pressure through a sustained protective NPQ, not related to photodamage, as revealed by the unusually quick restoration of photosystem II (PSII) function in the dark. This might suggest either the occurrence of transient PSII photoinactivation or a fast rate of PSII repair cycle.

TH-CD-209-10: Scanning Proton Arc Therapy (SPArc) - The First Robust and Delivery-Efficient Spot Scanning Proton Arc Therapy

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

Ding, X; Li, X; Zhang, J

Purpose: To develop a delivery-efficient proton spot-scanning arc therapy technique with robust plan quality. Methods: We developed a Scanning Proton Arc(SPArc) optimization algorithm integrated with (1)Control point re-sampling by splitting control point into adjacent sub-control points; (2)Energy layer re-distribution by assigning the original energy layers to the new sub-control points; (3)Energy layer filtration by deleting low MU weighting energy layers; (4)Energy layer re-sampling by sampling additional layers to ensure the optimal solution. A bilateral head and neck oropharynx case and a non-mobile lung target case were tested. Plan quality and total estimated delivery time were compared to original robust optimizedmore » multi-field step-and-shoot arc plan without SPArc optimization (Arcmulti-field) and standard robust optimized Intensity Modulated Proton Therapy(IMPT) plans. Dose-Volume-Histograms (DVH) of target and Organ-at-Risks (OARs) were analyzed along with all worst case scenarios. Total delivery time was calculated based on the assumption of a 360 degree gantry room with 1 RPM rotation speed, 2ms spot switching time, beam current 1nA, minimum spot weighting 0.01 MU, energy-layer-switching-time (ELST) from 0.5 to 4s. Results: Compared to IMPT, SPArc delivered less integral dose(−14% lung and −8% oropharynx). For lung case, SPArc reduced 60% of skin max dose, 35% of rib max dose and 15% of lung mean dose. Conformity Index is improved from 7.6(IMPT) to 4.0(SPArc). Compared to Arcmulti-field, SPArc reduced number of energy layers by 61%(276 layers in lung) and 80%(1008 layers in oropharynx) while kept the same robust plan quality. With ELST from 0.5s to 4s, it reduced 55%–60% of Arcmulti-field delivery time for the lung case and 56%–67% for the oropharynx case. Conclusion: SPArc is the first robust and delivery-efficient proton spot-scanning arc therapy technique which could be implemented in routine clinic. For modern proton machine with ELST close to 0.5s, SPArc would be a popular treatment option for both single and multi-room center.« less

Under Lock and Key: Preventing Campus Theft of Electronic Equipment.

ERIC Educational Resources Information Center

Harrison, J. Phil

1996-01-01

A discussion of computer theft prevention on college campuses looks at a variety of elements in electronic equipment security, including the extent of the problem, physical antitheft products, computerized access, control of key access, alarm systems, competent security personnel, lighting, use of layers of protection, and increasing…

Bulk Superconductors in Mobile Application

NASA Astrophysics Data System (ADS)

Werfel, F. N.; Delor, U. Floegel-; Rothfeld, R.; Riedel, T.; Wippich, D.; Goebel, B.; Schirrmeister, P.

We investigate and review concepts of multi - seeded REBCO bulk superconductors in mobile application. ATZ's compact HTS bulk magnets can trap routinely 1 T@77 K. Except of magnetization, flux creep and hysteresis, industrial - like properties as compactness, power density, and robustness are of major device interest if mobility and light-weight construction is in focus. For mobile application in levitated trains or demonstrator magnets we examine the performance of on-board cryogenics either by LN2 or cryo-cooler application. The mechanical, electric and thermodynamical requirements of compact vacuum cryostats for Maglev train operation were studied systematically. More than 30 units are manufactured and tested. The attractive load to weight ratio is more than 10 and favours group module device constructions up to 5 t load on permanent magnet (PM) track. A transportable and compact YBCO bulk magnet cooled with in-situ 4 Watt Stirling cryo-cooler for 50 - 80 K operation is investigated. Low cooling power and effective HTS cold mass drives the system construction to a minimum - thermal loss and light-weight design.

Ultra High p-doping Material Research for GaN Based Light Emitters

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

Vladimir Dmitriev

2007-06-30

The main goal of the Project is to investigate doping mechanisms in p-type GaN and AlGaN and controllably fabricate ultra high doped p-GaN materials and epitaxial structures. Highly doped p-type GaN-based materials with low electrical resistivity and abrupt doping profiles are of great importance for efficient light emitters for solid state lighting (SSL) applications. Cost-effective hydride vapor phase epitaxial (HVPE) technology was proposed to investigate and develop p-GaN materials for SSL. High p-type doping is required to improve (i) carrier injection efficiency in light emitting p-n junctions that will result in increasing of light emitting efficiency, (ii) current spreading inmore » light emitting structures that will improve external quantum efficiency, and (iii) parameters of Ohmic contacts to reduce operating voltage and tolerate higher forward currents needed for the high output power operation of light emitters. Highly doped p-type GaN layers and AlGaN/GaN heterostructures with low electrical resistivity will lead to novel device and contact metallization designs for high-power high efficiency GaN-based light emitters. Overall, highly doped p-GaN is a key element to develop light emitting devices for the DOE SSL program. The project was focused on material research for highly doped p-type GaN materials and device structures for applications in high performance light emitters for general illumination P-GaN and p-AlGaN layers and multi-layer structures were grown by HVPE and investigated in terms of surface morphology and structure, doping concentrations and profiles, optical, electrical, and structural properties. Tasks of the project were successfully accomplished. Highly doped GaN materials with p-type conductivity were fabricated. As-grown GaN layers had concentration N{sub a}-N{sub d} as high as 3 x 10{sup 19} cm{sup -3}. Mechanisms of doping were investigated and results of material studies were reported at several International conferences providing better understanding of p-type GaN formation for Solid State Lighting community. Grown p-type GaN layers were used as substrates for blue and green InGaN-based LEDs made by HVPE technology at TDI. These results proved proposed technical approach and facilitate fabrication of highly conductive p-GaN materials by low-cost HVPE technology for solid state lighting applications. TDI has started the commercialization of p-GaN epitaxial materials.« less

Multi-sensor physical activity recognition in free-living.

PubMed

Ellis, Katherine; Godbole, Suneeta; Kerr, Jacqueline; Lanckriet, Gert

Physical activity monitoring in free-living populations has many applications for public health research, weight-loss interventions, context-aware recommendation systems and assistive technologies. We present a system for physical activity recognition that is learned from a free-living dataset of 40 women who wore multiple sensors for seven days. The multi-level classification system first learns low-level codebook representations for each sensor and uses a random forest classifier to produce minute-level probabilities for each activity class. Then a higher-level HMM layer learns patterns of transitions and durations of activities over time to smooth the minute-level predictions. [Formula: see text].

A fiber-based implantable multi-optrode array with contiguous optical and electrical sites

NASA Astrophysics Data System (ADS)

Chen, Sanyuan; Pei, Weihua; Gui, Qiang; Chen, Yuanfang; Zhao, Shanshan; Wang, Huan; Chen, Hongda

2013-08-01

Objective. Although various kinds of optrodes are designed to deliver light and sense electrophysiological responses, few have a tightly closed optical delivering site or electrical recording site. The large space between them often blurs the stimulation location and light intensity threshold. Approach. Based on an optical fiber, we develop an optrode structure which has a coniform tip where the light exit point and gold-based electrode site are located. The optrode is fabricated by integrating a metal membrane electrode on the outside of a tapered fiber. Half of the cone-shape tip is covered by a layer of gold membrane to form the electrode. A commercial fiber connector, mechanical transfer (MT) module, is chosen to assemble the multi-optrode array (MOA). The MT connector acts as both the holder of the optrode array and an aligning part to connect the MOA with the light source. Main results. We fabricated a pluggable MOA weighing only 0.2 g. The scanning electron microscope images showed a tight cover of the metal layer on the optrode tip with an exposure area of 1500 µm2. The electrochemical impedance of the optrode at 1 kHz was 100 kΩ on average and the light emission intensity reached 13 mW. The optical modulating and electrophysiological recording ability of the MOA was validated by monitoring the response of cells in a ChR2-expressing mouse's cerebral cortex. Neurons that maintained high cluster quality (signal-to-noise ratio = 5:1) and coherence in response to trains of 20 Hz stimulation were monitored. Significance. The optrode array reduces the distance between the optical stimulating sites and electrophysiological sites dramatically and can supply multiple channels to guide different lights simultaneously. This optrode with its novel structure may lead to a different kind of optical neural control prosthetic device, opening up a new option for neural modulation in the brain.

Using GIS for Developing Sustainable Urban Growth Case Kyrenia Region

NASA Astrophysics Data System (ADS)

Kara, C.; Akçit, N.

2018-03-01

It is critical to develop urban layers for analysis sustainable urban development possibilities within planning process. Kyrenia Region has many physical, environmental or economic issues that may danger the growth possibilities in sustainable manner. From this point, this study uses different spatial layers such as slope, distance to roads, distance to central zone, vegetation, soil productivity, environmental protection zones, distance to open/green space, distance to education for supporting sustainable urban growth policies and define suitable areas for urban development within this perspective. The study tries to convert sustainable urban growth policies such as; compact growth, environmental protection, equal accessibility to basic services; into spatial layers and establish proper framework for multi criteria evaluation in Kyrenia Region within using geographical information systems. It shows suitability values for Kyrenia region and constraints zones at final section. It clearly presents the suitable areas for the sustainable urbanization and also unsuitable or risky areas for reducing the possible disasters and may happen in the future.

Design and analysis on robotic arm for serving hazard container

NASA Astrophysics Data System (ADS)

Razali, Zol Bahri; Kader, Mohamed Mydin M. Abdul; Yi, Khoo Zern; Daud, Mohd Hisam

2017-09-01

This paper presents about design, analyses development and fabrication of robotic arm for sorting multi-material. The major problem that urges the initiation of the project is the fact that manufacturing industry is growing at relatively faster rate. Most of the company produce high load robotic arm. Less company creates light weight, and affordable robotic arm. As the result, light weight and affordable robot is developing to cover this issue. Plastic material was used to construct the body of the robotic arm, and an optical sensor was implemented to provide basic recognition of object to be carried. The robotic arm used five servomotors for overall operation; four for its joints, and one for the gripping mechanism. The gripper was designed and fabricated using Perspex due to the light weight and high strength of the material. The operation of the robotic arm was governed by Basic Stamp programming sequence and the device was expected to differentiate material and other objects based on reflective theory, and perform subsequent operations afterwards. The SolidWorks was used to model the detail design of the robotic arm, and to simulate the motion of the device.

Protection against hip fractures by energy absorption.

PubMed

Lauritzen, J B; Askegaard, V

1992-02-01

Impact lateral to the hip was noted in 37 of 60 patients with hip fracture. Women with hip fracture (n = 12) had an average 22 mm thick soft tissue cover of the hip as compared to 32 mm in healthy women (n = 27), even for the same body mass index. Experiments where a steel weight was dropped from various heights onto porcine soft tissue showed that a layer of 29 mm could absorb 60% more energy than a 20 mm thick layer before nearly metallic contact would occur, corresponding to a sharp rise in load. If the results are related to conditions in vivo, then the passive protection of soft tissue over the hip is important for the development of hip fractures, and may under certain assumptions explain the higher risk of hip fractures in thin persons. An external hip protection device might therefore prevent some hip fractures.

A Social-Ecological Framework of Theory, Assessment, and Prevention of Suicide

PubMed Central

Cramer, Robert J.; Kapusta, Nestor D.

2017-01-01

The juxtaposition of increasing suicide rates with continued calls for suicide prevention efforts begs for new approaches. Grounded in the Centers for Disease Control and Prevention (CDC) framework for tackling health issues, this personal views work integrates relevant suicide risk/protective factor, assessment, and intervention/prevention literatures. Based on these components of suicide risk, we articulate a Social-Ecological Suicide Prevention Model (SESPM) which provides an integration of general and population-specific risk and protective factors. We also use this multi-level perspective to provide a structured approach to understanding current theories and intervention/prevention efforts concerning suicide. Following similar multi-level prevention efforts in interpersonal violence and Human Immunodeficiency Virus (HIV) domains, we offer recommendations for social-ecologically informed suicide prevention theory, training, research, assessment, and intervention programming. Although the SESPM calls for further empirical testing, it provides a suitable backdrop for tailoring of current prevention and intervention programs to population-specific needs. Moreover, the multi-level model shows promise to move suicide risk assessment forward (e.g., development of multi-level suicide risk algorithms or structured professional judgments instruments) to overcome current limitations in the field. Finally, we articulate a set of characteristics of social-ecologically based suicide prevention programs. These include the need to address risk and protective factors with the strongest degree of empirical support at each multi-level layer, incorporate a comprehensive program evaluation strategy, and use a variety of prevention techniques across levels of prevention. PMID:29062296

Nano-engineering of superhydrophobic aluminum surfaces for anti-corrosion

NASA Astrophysics Data System (ADS)

Jeong, Chanyoung

Metal corrosion is a serious problem, both economically and operationally, for engineering systems such as aircraft, automobiles, pipelines, and naval vessels. In such engineering systems, aluminum is one of the primary materials of construction due to its light weight compared to steel and good general corrosion resistance. However, because of aluminum's relatively lower resistance to corrosion in salt water environments, protective measures such as thick coatings, paints, or cathodic protection must be used for satisfactory service life. Unfortunately, such anti-corrosion methods can create other concerns, such as environmental contamination, protection durability, and negative impact on hydrodynamic efficiency. Recently, a novel approach to preventing metal corrosion has emerged, using superhydrophobic surfaces. Superhydrophobic surfaces create a composite interface to liquid by retaining air within the surface structures, thus minimizing the direct contact of the liquid environment to the metal surface. The result is a highly non-wetting and anti-adherent surface that can offer other benefits such as biofouling resistance and hydrodynamic low friction. Prior research with superhydrophobic surfaces for corrosion applications was based on irregular surface roughening and/or chemical coatings, which resulted in random surface features, mostly on the micrometer scale. Such microscale surface roughness with poor controllability of structural dimensions and shapes has been a critical limitation to deeper understanding of the anti-corrosive effectiveness and optimized application of this approach. The research reported here provides a novel approach to producing controlled superhydrophobic nanostructures on aluminum that allows a systematic investigation of the superhydrophobic surface parameters on the corrosion resistance and hence can provide a route to optimization of the surface. Electrochemical anodization is used to controllably modulate the oxide layer thickness and pore dimensions at the aluminum surface. The results show that thicker oxide layers with larger pore sizes allow the nanostructured surface to retain more gas (air) and hence provide a more effective barrier to corrosion. The anodizing techniques are further advanced to design and produce hierarchical three-dimensional nanostructures for better retention of the gaseous barrier layer at the surface.

Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

NASA Astrophysics Data System (ADS)

Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

2016-08-01

In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

Microcapsules and Methods for Making

NASA Technical Reports Server (NTRS)

Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

1998-01-01

Methods of forming multi-lamellar microcapsules having alternating layers of hydrophilic and hydrophobic immiscible liquid phases have been developed using different polymer/solvent systems. The methods use liquid-liquid diffusion and simultaneous lateral phase separation, controlled by proper timed-sequence exposures of immiscible phases and low shear mixing, to form narrow size distributions of spherical, multilamellar microcapsules. The use of special formulations of solubilized drugs, surfactants, and polymeric co-surfactants in aqueous vehicles which are dispersed in hydrocarbon solvents containing small quantities of oil, low molecular weight co-surfactants and glycerides that are aqueous insoluble enables the formation of unique microcapsules which can carry large amounts of pharmaceuticals in both aqueous and non-aqueous solvent compartments. The liquid microcapsules are quickly formed in a single step and can include a polymeric outer 'skin' which protects the microcapsules during physical manipulation or exposure to high shear forces. Water-in-oil and oil-in-water microcapsules have been formed both in 1 x g and in microgravity, which contain several types of drugs co-encapsulated within different fluid compartments inside the same microcapsule. Large, spherical multi-lamellar microcapsules have been formed including a cytotoxic drug co-encapsulated with a radiocontrast medium which has advantages for chemoembolization of vascular tumors. In certain cases, crystals of the drug form inside the microcapsules providing zero-order and first order, sustained drug release kinetics.

A novel carbohydrate-binding surface layer protein from the hyperthermophilic archaeon Pyrococcus horikoshii.

PubMed

Goda, Shuichiro; Koga, Tomoyuki; Yamashita, Kenichiro; Kuriura, Ryo; Ueda, Toshifumi

2018-04-08

In Archaea and Bacteria, surface layer (S-layer) proteins form the cell envelope and are involved in cell protection. In the present study, a putative S-layer protein was purified from the crude extract of Pyrococcus horikoshii using affinity chromatography. The S-layer gene was cloned and expressed in Escherichia coli. Isothermal titration calorimetry analyses showed that the S-layer protein bound N-acetylglucosamine and induced agglutination of the gram-positive bacterium Micrococcus lysodeikticus. The protein comprised a 21-mer structure, with a molecular mass of 1,340 kDa, as determined using small-angle X-ray scattering. This protein showed high thermal stability, with a midpoint of thermal denaturation of 79 °C in dynamic light scattering experiments. This is the first description of the carbohydrate-binding archaeal S-layer protein and its characteristics.

On-Orbit Teflon FEP Degradation

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline A.; Hansen, Patricia A.; Dever, Joyce A.

1998-01-01

During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon' FEP (fluorinated ethylene propylene), used as the outer layer of the multi-layer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon FEP sample evaluation and additional testing of pristine Teflon FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations, and that the damage increased with the combined total dose of electrons, protons, LTV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the Teflon FEP.

On-Orbit Teflon(trademark) FEP Degradation

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline; Hansen, Patricia A.; Dever, Joyce A.

1999-01-01

During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon(trademark) FEP (fluorinated ethylene propylene), used as the outer layer of the multi-layer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon(trademark) FEP sample evaluation and additional testing of pristine Teflon FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations, and that the damage increased with the combined total dose of electrons, protons, UV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the Teflon(trademark) FEP.

Multi-Objective Flight Control for Drag Minimization and Load Alleviation of High-Aspect Ratio Flexible Wing Aircraft

NASA Technical Reports Server (NTRS)

Nguyen, Nhan; Ting, Eric; Chaparro, Daniel; Drew, Michael; Swei, Sean

2017-01-01

As aircraft wings become much more flexible due to the use of light-weight composites material, adverse aerodynamics at off-design performance can result from changes in wing shapes due to aeroelastic deflections. Increased drag, hence increased fuel burn, is a potential consequence. Without means for aeroelastic compensation, the benefit of weight reduction from the use of light-weight material could be offset by less optimal aerodynamic performance at off-design flight conditions. Performance Adaptive Aeroelastic Wing (PAAW) technology can potentially address these technical challenges for future flexible wing transports. PAAW technology leverages multi-disciplinary solutions to maximize the aerodynamic performance payoff of future adaptive wing design, while addressing simultaneously operational constraints that can prevent the optimal aerodynamic performance from being realized. These operational constraints include reduced flutter margins, increased airframe responses to gust and maneuver loads, pilot handling qualities, and ride qualities. All of these constraints while seeking the optimal aerodynamic performance present themselves as a multi-objective flight control problem. The paper presents a multi-objective flight control approach based on a drag-cognizant optimal control method. A concept of virtual control, which was previously introduced, is implemented to address the pair-wise flap motion constraints imposed by the elastomer material. This method is shown to be able to satisfy the constraints. Real-time drag minimization control is considered to be an important consideration for PAAW technology. Drag minimization control has many technical challenges such as sensing and control. An initial outline of a real-time drag minimization control has already been developed and will be further investigated in the future. A simulation study of a multi-objective flight control for a flight path angle command with aeroelastic mode suppression and drag minimization demonstrates the effectiveness of the proposed solution. In-flight structural loads are also an important consideration. As wing flexibility increases, maneuver load and gust load responses can be significant and therefore can pose safety and flight control concerns. In this paper, we will extend the multi-objective flight control framework to include load alleviation control. The study will focus initially on maneuver load minimization control, and then subsequently will address gust load alleviation control in future work.

Towards efficient and cost-effective inverted hybrid organic solar cells using inorganic semiconductor in the active layer

NASA Astrophysics Data System (ADS)

Imran, M.; Ikram, M.; Dilpazir, S.; Nafees, M.; Ali, S.; Geng, J.

2017-11-01

The article investigates the effects of NiO (p-type) and TiO2 (n-type) nanoparticles (NPs) on the performance of poly(3-hexylthiophene) (P3HT) and (phenyl-C61-butyric acid methylester) (PCBM) based devices with an inverse geometry. Various weight ratios of these nanoparticles were mixed in the polymer solution using 1,2-dichlorobenzene as solvent. An optimal amount of NPs-doped active layer exhibited higher power conversion efficiency (PCE) of 3.85% as compared to the reference cell, which exhibited an efficiency of 3.40% under white light illumination intensity of 100 mW/cm2. Enhanced PCE originates from increased film roughness and light harvesting due to increased absorption range upon mixing an optimal amount of NPs in the organic-based active layer. Further addition of NiO and TiO2 concentration relative to PCBM resulted in significant agglomeration of nanoparticles leading to degraded device parameters.

Superalloy Foams for Aeroshell Applications

NASA Technical Reports Server (NTRS)

Gayda, John; Padula, Santo, II

2001-01-01

Current thermal protection systems for reentry from space, such as that employed on the space shuttle, rely on ceramic tiles with ultra-low conductivity. These materials provide excellent thermal protection but are extremely fragile, easily degraded by environmental attack, and carry no structural loads. Future thermal protection systems being proposed in NASAs MITAS Program will attempt to combine thermal protection with improved durability and structural capability without significant increases in vehicle weight. This may be accomplished by combining several materials in a layered structure to obtain the desired function for aeroshell applications. One class of materials being considered for inclusion in this concept are high temperature metal foam. The objective of this paper was to fabricate low density, superalloy foams and conduct limited testing to evaluate their thermal and structural capabilities. Superalloys were chosen for evaluation as they possesses good strength and excellent environmental endurance over a wide range of temperatures. Utilizing superalloys as low density foams, with porosity contents greater than 90%, minimizes weight and thermal conductivity.

Foam core shield (FCS) systems : a new dual - purpose technology for shielding against meteoroid strike damage and for thermal control of spacecrafts/satellite components

NASA Technical Reports Server (NTRS)

Adams, Marc A.; Zwissler, James G.; Hayes, Charles; Fabensky, Beth; Cornelison, Charles; Alexander, Lesley; Bishop, Karen

2005-01-01

A new technology is being developed that can protect spacecraft and satellite components against damage from meteoroid strikes and control the thermal environment of the protected components. This technology, called Foam Core Shield (FCS) systems, has the potential to replace the multi-layer insulation blankets (MLI) that have been used on spacecraft for decades. In order to be an attractive candidate for replacing MLI, FCS systems should not only provide superior protection against meteoroid strikes but also provide an equal or superior ability to control the temperature of the protected component. Properly designed FCS systems can provide these principal functions, meteoroid strike protection and thermal control, with lower system mass and a smaller system envelope than ML.

A multi-objective assessment of an air quality monitoring network using environmental, economic, and social indicators and GIS-based models.

PubMed

Pope, Ronald; Wu, Jianguo

2014-06-01

In the United States, air pollution is primarily measured by Air Quality Monitoring Networks (AQMN). These AQMNs have multiple objectives, including characterizing pollution patterns, protecting the public health, and determining compliance with air quality standards. In 2006, the U.S. Environmental Protection Agency issued a directive that air pollution agencies assess the performance of their AQMNs. Although various methods to design and assess AQMNs exist, here we demonstrate a geographic information system (GIS)-based approach that combines environmental, economic, and social indicators through the assessment of the ozone (O3) and particulate matter (PM10) networks in Maricopa County, Arizona. The assessment was conducted in three phases: (1) to evaluate the performance of the existing networks, (2) to identify areas that would benefit from the addition of new monitoring stations, and (3) to recommend changes to the AQMN. A comprehensive set of indicators was created for evaluating differing aspects of the AQMNs' objectives, and weights were applied to emphasize important indicators. Indicators were also classified according to their sustainable development goal. Our results showed that O3 was well represented in the county with some redundancy in terms of the urban monitors. The addition of weights to the indicators only had a minimal effect on the results. For O3, urban monitors had greater social scores, while rural monitors had greater environmental scores. The results did not suggest a need for adding more O3 monitoring sites. For PM10, clustered urban monitors were redundant, and weights also had a minimal effect on the results. The clustered urban monitors had overall low scores; sites near point sources had high environmental scores. Several areas were identified as needing additional PM10 monitors. This study demonstrates the usefulness of a multi-indicator approach to assess AQMNs. Network managers and planners may use this method to assess the performance of air quality monitoring networks in urban regions. The U.S. Environmental Protection Agency issued a directive in 2006 that air pollution agencies assess the performance of their AQMNs; as a result, we developed a GIS-based, multi-objective assessment approach that integrates environmental, economic, and social indicators, and demonstrates its use through assessing the O3 and PM10 monitoring networks in the Phoenix metropolitan area. We exhibit a method of assessing network performance and identifying areas that would benefit from new monitoring stations; also, we demonstrate the effect of adding weights to the indicators. Our study shows that using a multi-indicator approach gave detailed assessment results for the Phoenix AQMN.

Optical manipulation of electron spin in quantum dot systems

NASA Astrophysics Data System (ADS)

Villas-Boas, Jose; Ulloa, Sergio; Govorov, Alexander

2006-03-01

Self-assembled quantum dots (QDs) are of particular interest for fundamental physics because of their similarity with atoms. Coupling two of such dots and addressing them with polarized laser light pulses is perhaps even more interesting. In this paper we use a multi-exciton density matrix formalism to model the spin dynamics of a system with single or double layers of QDs. Our model includes the anisotropic electron-hole exchange in the dots, the presence of wetting layer states, and interdot tunneling [1]. Our results show that it is possible to switch the spin polarization of a single self-assembled quantum dot under elliptically polarized light by increasing the laser intensity. In the nonlinear mechanism described here, intense elliptically polarized light creates an effective exchange channel between the exciton spin states through biexciton states, as we demonstrate by numerical and analytical methods. We further show that the effect persists in realistic ensembles of dots, and we propose alternative ways to detect it. We also extend our study to a double layer of quantum dots, where we find a competition between Rabi frequency and tunneling oscillations. [1] J. M. Villas-Boas, S. E. Ulloa, and A. O. Govorov, Phys. Rev. Lett. 94, 057404 (2005); Phys. Rev. B 69, 125342 (2004).

Single-Walled Carbon Nanotubes in Solar Cells.

PubMed

Jeon, Il; Matsuo, Yutaka; Maruyama, Shigeo

2018-01-22

Photovoltaics, more generally known as solar cells, are made from semiconducting materials that convert light into electricity. Solar cells have received much attention in recent years due to their promise as clean and efficient light-harvesting devices. Single-walled carbon nanotubes (SWNTs) could play a crucial role in these devices and have been the subject of much research, which continues to this day. SWNTs are known to outperform multi-walled carbon nanotubes (MWNTs) at low densities, because of the difference in their optical transmittance for the same current density, which is the most important parameter in comparing SWNTs and MWNTs. SWNT films show semiconducting features, which make SWNTs function as active or charge-transporting materials. This chapter, consisting of two sections, focuses on the use of SWNTs in solar cells. In the first section, we discuss SWNTs as a light harvester and charge transporter in the photoactive layer, which are reviewed chronologically to show the history of the research progress. In the second section, we discuss SWNTs as a transparent conductive layer outside of the photoactive layer, which is relatively more actively researched. This section introduces SWNT applications in silicon solar cells, organic solar cells, and perovskite solar cells each, from their prototypes to recent results. As we go along, the science and prospects of the application of solar cells will be discussed.

Preparing and Study the effects of Composite Coatings in Protection of Oil Pipes from the Risk of Corrosion that resulting from Associated water with Petroleum Products

NASA Astrophysics Data System (ADS)

– Sarraf, A. R. Al; Yaseen, M. A.

2018-05-01

In order to inhibit the metallic corrosion in the oil pipelines,the protection method with composite coating of unsaturated polyester and reinforced by Caolin at weight percentage (20%) was studied. Where, the work samples were classified into two groups according to internal composite coatings layers for all groups of these samples. The first group is nitrocellulose coating reinforced by nano and micro powder of Mgo, the second group is sodium silicate coating reinforced by nano powder of Mgo. The following weight percentages (0%, 1%, 3% and 5%) were adopted as reinforcement ratios for nano powders, as well as the weight percentages (0%, 3%, 5% and 7%) as reinforcement ratios for micro powders Tribology properties and Electrochemical Corrosion Resistance by Polarization method (Tafel) and Adhesion Strength were studied. The results showed an improvement in the corrosion resistance of protected steel by coatings compare with uncoated steel, as well as improvement in mechanical properties and adhesion strength of composite coatings.

Landsat imagery: a unique resource

USGS Publications Warehouse

Miller, H.; Sexton, N.; Koontz, L.

2011-01-01

Landsat satellites provide high-quality, multi-spectral imagery of the surface of the Earth. These moderate-resolution, remotely sensed images are not just pictures, but contain many layers of data collected at different points along the visible and invisible light spectrum. These data can be manipulated to reveal what the Earth’s surface looks like, including what types of vegetation are present or how a natural disaster has impacted an area (Fig. 1).

Molybdenum Disulfide as a Protection Layer and Catalyst for Gallium Indium Phosphide Solar Water Splitting Photocathodes

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

Britto, Reuben J.; Benck, Jesse D.; Young, James L.

2016-06-02

Gallium indium phosphide (GaInP2) is a semiconductor with promising optical and electronic properties for solar water splitting, but its surface stability is problematic as it undergoes significant chemical and electrochemical corrosion in aqueous electrolytes. Molybdenum disulfide (MoS2) nanomaterials are promising to both protect GaInP2 and to improve catalysis since MoS2 is resistant to corrosion and also possesses high activity for the hydrogen evolution reaction (HER). In this work, we demonstrate that GaInP2 photocathodes coated with thin MoS2 surface protecting layers exhibit excellent activity and stability for solar hydrogen production, with no loss in performance (photocurrent onset potential, fill factor, andmore » light limited current density) after 60 hours of operation. This represents a five-hundred fold increase in stability compared to bare p-GaInP2 samples tested in identical conditions.« less

Structure of sunspot light bridges in the chromosphere and transition region

NASA Astrophysics Data System (ADS)

Rezaei, R.

2018-01-01

Context. Light bridges (LBs) are elongated structures with enhanced intensity embedded in sunspot umbra and pores. Aims: We studied the properties of a sample of 60 LBs observed with the Interface Region Imaging Spectrograph (IRIS). Methods: Using IRIS near- and far-ultraviolet spectra, we measured the line intensity, width, and Doppler shift; followed traces of LBs in the chromosphere and transition region (TR); and compared LB parameters with umbra and quiet Sun. Results: There is a systematic emission enhancement in LBs compared to nearby umbra from the photosphere up to the TR. Light bridges are systematically displaced toward the solar limb at higher layers: the amount of the displacement at one solar radius compares well with the typical height of the chromosphere and TR. The intensity of the LB sample compared to the umbra sample peaks at the middle/upper chromosphere where they are almost permanently bright. Spectral lines emerging from the LBs are broader than the nearby umbra. The systematic redshift of the Si IV line in the LB sample is reduced compared to the quiet Sun sample. We found a significant correlation between the line width of ions arising at temperatures from 3 × 104 to 1.5 × 105 K as there is also a strong spatial correlation among the line and continuum intensities. In addition, the intensity-line width relation holds for all spectral lines in this study. The correlations indicate that the cool and hot plasma in LBs are coupled. Conclusions: Light bridges comprise multi-temperature and multi-disciplinary structures extending up to the TR. Diverse heating sources supply the energy and momentum to different layers, resulting in distinct dynamics in the photosphere, chromosphere, and TR.

Light distribution in plant canopies: A comparison between 1-D multi-layer modeling approach and 3-D ray tracing

NASA Astrophysics Data System (ADS)

Srinivasan, V.; Yiwen, X.; Ellis, A.; Christensen, A.; Borkiewic, K.; Cox, D.; Hart, J.; Long, S.; Marshall-Colon, A.

2016-12-01

The distribution of absorbed solar radiation in the photosynthetically active region wavelength (PAR) within plant canopies plays a critical role in determining photosynthetic carbon uptake and its associated transpiration. The vertical distribution of leaf area, leaf angles, leaf absorptivity and reflectivity within the canopy, affect the distribution of PAR absorbed throughout the canopy. While the upper canopy sunlit leaves absorb most of the incoming PAR and hence contribute most towards total canopy carbon uptake, the lower canopy shaded leaves which receive mostly lower intensity diffuse PAR make significant contributions towards plant carbon uptake. Most detailed vegetation models use a 1-D vertical multi-layer approach to model the sunlight and shaded canopy leaf fractions, and quantify the direct and diffuse radiation absorbed by the respective leaf fractions. However, this approach is only applicable under canopy closure conditions, and furthermore it fails to accurately capture the effects of diurnally varying leaf angle distributions in some plant canopies. Here, we show by using a 3-D ray tracing model which uses an explicit 3-D canopy structure that enforces no conditions about canopy closure, that the effects of diurnal variation of canopy leaf angle distributions better match with observed data. Our comparative analysis performed on soybean crop canopies between 3-D ray tracing model and the multi-layer model shows that the distribution of absorbed direct PAR is not exponential while, the distribution of absorbed diffuse PAR radiation within plant canopies is exponential. These results show the multi-layer model to significantly over-predict canopy PAR absorbed, and in turn significantly overestimate photosynthetic carbon uptake by up to 13% and canopy transpiration by 7% under mid-day sun conditions as verified through our canopy chamber experiments. Our results indicate that current detailed 1-D multi-layer canopy radiation attenuation models significantly over predict canopy radiation absorption and its associated canopy photosynthetic and transpiration fluxes, and use of a 3-D ray tracing model provides more realistic predictions of leaf canopy integrated fluxes of carbon and water.

Multilayer motif analysis of brain networks

NASA Astrophysics Data System (ADS)

Battiston, Federico; Nicosia, Vincenzo; Chavez, Mario; Latora, Vito

2017-04-01

In the last decade, network science has shed new light both on the structural (anatomical) and on the functional (correlations in the activity) connectivity among the different areas of the human brain. The analysis of brain networks has made possible to detect the central areas of a neural system and to identify its building blocks by looking at overabundant small subgraphs, known as motifs. However, network analysis of the brain has so far mainly focused on anatomical and functional networks as separate entities. The recently developed mathematical framework of multi-layer networks allows us to perform an analysis of the human brain where the structural and functional layers are considered together. In this work, we describe how to classify the subgraphs of a multiplex network, and we extend the motif analysis to networks with an arbitrary number of layers. We then extract multi-layer motifs in brain networks of healthy subjects by considering networks with two layers, anatomical and functional, respectively, obtained from diffusion and functional magnetic resonance imaging. Results indicate that subgraphs in which the presence of a physical connection between brain areas (links at the structural layer) coexists with a non-trivial positive correlation in their activities are statistically overabundant. Finally, we investigate the existence of a reinforcement mechanism between the two layers by looking at how the probability to find a link in one layer depends on the intensity of the connection in the other one. Showing that functional connectivity is non-trivially constrained by the underlying anatomical network, our work contributes to a better understanding of the interplay between the structure and function in the human brain.

Output-increasing, protective cover for a solar cell

DOEpatents

Hammerbacher, Milfred D.

1995-11-21

A flexible cover (14) for a flexible solar cell (12) protects the cell from the ambient and increases the cell's efficiency. The cell(12)includes silicon spheres (16) held in a flexible aluminum sheet matrix (20,22). The cover (14) is a flexible, protective layer (60) of light-transparent material having a relatively flat upper, free surface (64) and an irregular opposed surface (66). The irregular surface (66) includes first portions (68) which conform to the polar regions (31R) of the spheres (16) and second convex (72) or concave (90) portions (72 or 90) which define spaces (78) in conjunction with the reflective surface (20T) of one aluminum sheet (20). Without the cover (14) light (50) falling on the surface (20T) between the spheres (16) is wasted, that is, it does not fall on a sphere (16). The surfaces of the second portions are non-parallel to the direction of the otherwise wasted light (50), which fact, together with a selected relationship between the refractive indices of the cover and the spaces, result in sufficient diffraction of the otherwise wasted light (50) so that about 25% of it is reflected from the surface (20T) onto a sphere (16).

Exploring structural colour in uni- and multi-coloured butterfly wings and Ag+ uptake by scales

NASA Astrophysics Data System (ADS)

Aideo, Swati N.; Haloi, Rajib; Mohanta, Dambarudhar

2017-09-01

We discuss the origin of the structural colour of different butterfly wings in the light of the typical built-in microstructural arrangement of scales that are comprised of chitin-melanin layer and air-gaps. Three specimens of butterfly wings namely, Papilio Liomedon (black), Catopsilia Pyranthe (light green) and Vanessa Cardui (multi-coloured) were chosen and diffuse reflectance characteristics have been aquired for normal incidence of p-polarized light. Moreover, the time-dependent uptake of Ag+ into scales has led to swelling and spread of the chitinous ridges and ribs, with revelation of micro-beads in Catopsilia Pyranthe specimen. The reduction of the number of air-gaps between any two parallel ridges is attributed to the merging of adjacent gaps possessing a common boundary. The availability of Ag at the centre of a chosen ridge, for every wing type, follows an exponential growing trend, ∼e0.36t . Precise inclusion of nanoscale metals into natural photonic systems would provide new insight, while applying principles of photonics and plasmonics simultaneously.

Influence of Near-Surface Severe Plastic Deformation of Mild Steel on the Inhibition Performance of Sodium Molybdate and 1H-Benzotriazole in Artificial Sea Water

NASA Astrophysics Data System (ADS)

Sabet Bokati, Kazem; Dehghanian, Changiz; Babaei, Mahdi

2018-02-01

The effects of near-surface severe plastic deformation (NS-SPD) on the inhibition performance of sodium molybdate (SM) and 1H-benzotriazole (BTA) for mild steel were investigated using weight loss, polarization and electrochemical impedance spectroscopy measurements. The crystal grain size of NS-SPD-processed surface was analyzed by x-ray diffractometry and field emission scanning electron microscopy. A deformed layer with thickness of 20 ± 5 µm was produced on mild steel surface after NS-SPD process due to accumulated strains. The NS-SPD process caused more effective adsorption of corrosion inhibitors due to the fabrication of a surface with a high density of preferential adsorption sites. However, the stability of protective layer was predominantly influenced by the effect of NS-SPD process on inhibition efficiency. The fairly good persistence of protective layer formed on the surface by SM-containing solution and also positive effect of NS-SPD process on adsorption of molybdate ions caused higher inhibition performance for sodium molybdate. However, NS-SPD process encouraged deterioration of protective layer formed on steel surface in the presence of BTA inhibitor. It was ascribed to partial coverage of surface, low stability of adsorbed layer and thus more adsorption of aggressive ions on unprotected area which was uncovered during immersion time.

Iridescent colour production in hairs of blind golden moles (Chrysochloridae).

PubMed

Snyder, Holly K; Maia, Rafael; D'Alba, Liliana; Shultz, Allison J; Rowe, Karen M C; Rowe, Kevin C; Shawkey, Matthew D

2012-06-23

Relative to other metazoans, the mammalian integument is thought to be limited in colour. In particular, while iridescence is widespread among birds and arthropods, it has only rarely been reported in mammals. Here, we examine the colour, morphology and optical mechanisms in hairs from four species of golden mole (Mammalia: Chrysochloridae) that are characterized by sheens ranging from purple to green. Microspectrophotometry reveals that this colour is weak and variable. Iridescent hairs are flattened and have highly reduced cuticular scales, providing a broad and smooth surface for light reflection. These scales form multiple layers of light and dark materials of consistent thickness, strikingly similar to those in the elytra of iridescent beetles. Optical modelling suggests that the multi-layers produce colour through thin-film interference, and that the sensitivity of this mechanism to slight changes in layer thickness and number explains colour variability. While coloured integumentary structures are typically thought to evolve as sexual ornaments, the blindness of golden moles suggests that the colour may be an epiphenomenon resulting from evolution via other selective factors, including the ability to move and keep clean in dirt and sand.

New developments in the law for obesity discrimination protection.

PubMed

Pomeranz, Jennifer L; Puhl, Rebecca M

2013-03-01

Obese individuals are frequent targets of weight-based discrimination, particularly in the employment setting. Victims of weight discrimination have sought legal restitution like others who have suffered from different forms of discrimination. However, in the vast majority of the United States, body weight is not a protected class and weight-based employment discrimination does not provide a basis for a legal claim. Some have attempted to seek legal recourse under the Rehabilitation Act of 1973 or the Americans with Disabilities Act of 1990 (collectively, the ADA), which protect against discrimination based on mental or physical disabilities in a variety of settings. Until recently, claims of weight discrimination under the ADA have also been largely unsuccessful. However, Congress recently passed the ADA Amendments Act, expanding the definition of what constitutes a disability and incorporating a broad view of ADA's coverage. This short communication provides an update of the law as it relates to employment based discrimination of obese people. The authors propose a legislative direction for future legal recourse. The authors conducted legal research into the ADA Amendments Act, and synthesized this work relating to discrimination against weight in the employment context. In light of the ADA Amendments Act, courts and the Equal Employment Opportunity Commission have provided protection for severely obese people from discrimination based on actual or perceived disability in the employment context. The authors discuss this positive legal development and additionally propose a targeted solution to address weight discrimination in the employment setting. National polling suggests there is considerable public support for such a measure. The authors thus recommend the implementation of a "Weight Discrimination in Employment Act" modeled after the Age Discrimination in Employment Act to adequately address this pervasive and damaging injustice toward individuals who are affected by obesity. Copyright © 2013 The Obesity Society.

Concepts for the development of light-weight composite structures for rotor burst containment

NASA Technical Reports Server (NTRS)

Holms, A. G.

1977-01-01

Based on published results on rotor burst containment with single materials, and on body armor using composite materials, a set of hypotheses is established as to what variables might control the design of a weight-efficient protective device. Based on modern concepts for the design and analysis of small optimum seeking experiments, a particular experiment for evaluating the hypotheses and materials was designed. The design and methods for the analysis of results are described.

Material optimization of multi-layered enhanced nanostructures

NASA Astrophysics Data System (ADS)

Strobbia, Pietro

The employment of surface enhanced Raman scattering (SERS)-based sensing in real-world scenarios will offer numerous advantages over current optical sensors. Examples of these advantages are the intrinsic and simultaneous detection of multiple analytes, among many others. To achieve such a goal, SERS substrates with throughput and reproducibility comparable to commonly used fluorescence sensors have to be developed. To this end, our lab has discovered a multi-layer geometry, based on alternating films of a metal and a dielectric, that amplifies the SERS signal (multi-layer enhancement). The advantage of these multi-layered structures is to amplify the SERS signal exploiting layer-to-layer interactions in the volume of the structures, rather than on its surface. This strategy permits an amplification of the signal without modifying the surface characteristics of a substrate, and therefore conserving its reproducibility. Multi-layered structures can therefore be used to amplify the sensitivity and throughput of potentially any previously developed SERS sensor. In this thesis, these multi-layered structures were optimized and applied to different SERS substrates. The role of the dielectric spacer layer in the multi-layer enhancement was elucidated by fabricating spacers with different characteristics and studying their effect on the overall enhancement. Thickness, surface coverage and physical properties of the spacer were studied. Additionally, the multi-layered structures were applied to commercial SERS substrates and to isolated SERS probes. Studies on the dependence of the multi-layer enhancement on the thickness of the spacer demonstrated that the enhancement increases as a function of surface coverage at sub-monolayer thicknesses, due to the increasing multi-layer nature of the substrates. For fully coalescent spacers the enhancement decreases as a function of thickness, due to the loss of interaction between proximal metallic films. The influence of the physical properties of the spacer on the multi-layer enhancement were also studied. The trends in Schottky barrier height, interfacial potential and dielectric constant were isolated by using different materials as spacers (i.e., TiO2, HfO2, Ag 2O and Al2O3). The results show that the bulk dielectric constant of the material can be used to predict the relative magnitude of the multi-layer enhancement, with low dielectric constant materials performing more efficiently as spacers. Optimal spacer layers were found to be ultrathin coalescent films (ideally a monolayer) of low dielectric constant materials. Finally, multi-layered structures were observed to be employable to amplify SERS in drastically different substrate geometries. The multi-layered structures were applied to disposable commercial SERS substrates (i.e., Klarite). This project involved the regeneration of the used substrates, by stripping and redepositing the gold coating layer, and their amplification, by using the multi-layer geometry. The latter was observed to amplify the sensitivity of the substrates. Additionally, the multi-layered structures were applied to probes dispersed in solution. Such probes were observed to yield stronger SERS signal when optically trapped and to reduce the background signal. The application of the multi-layered structures on trapped probes, not only further amplified the SERS signal, but also increased the maximum number of applicable layers for the structures.

The impact of forest structure and light utilization on carbon cycling in tropical forests

NASA Astrophysics Data System (ADS)

Morton, D. C.; Longo, M.; Leitold, V.; Keller, M. M.

2015-12-01

Light competition is a fundamental organizing principle of forest ecosystems, and interactions between forest structure and light availability provide an important constraint on forest productivity. Tropical forests maintain a dense, multi-layered canopy, based in part on abundant diffuse light reaching the forest understory. Climate-driven changes in light availability, such as more direct illumination during drought conditions, therefore alter the potential productivity of forest ecosystems during such events. Here, we used multi-temporal airborne lidar data over a range of Amazon forest conditions to explore the influence of forest structure on gross primary productivity (GPP). Our analysis combined lidar-based observations of canopy illumination and turnover in the Ecosystem Demography model (ED, version 2.2). The ED model was updated to specifically account for regional differences in canopy and understory illumination using lidar-derived measures of canopy light environments. Model simulations considered the influence of forest structure on GPP over seasonal to decadal time scales, including feedbacks from differential productivity between illuminated and shaded canopy trees on mortality rates and forest composition. Finally, we constructed simple scenarios with varying diffuse and direct illumination to evaluate the potential for novel plant-climate interactions under scenarios of climate change. Collectively, the lidar observations and model simulations underscore the need to account for spatial heterogeneity in the vertical structure of tropical forests to constrain estimates of tropical forest productivity under current and future climate conditions.

Closing the Gap Between Research and Field Applications for Multi-UAV Cooperative Missions

DTIC Science & Technology

2013-09-01

IMU Inertial Measurement Units INCOSE International Council on Systems Engineering ISR Intelligence Surveillance and Reconnaissance ISTAR...light-weight and low-cost inertial measurement units ( IMUs ) are widely adopted for navigation of small- scale UAVs. Low-costs IMUs are characterized...by high measurement noises and large measurement biases. Hence pure initial navigation using low-cost IMUs drifts rapidly. In practice, inertial

Quantitative evaluation of deep and shallow tissue layers' contribution to fNIRS signal using multi-distance optodes and independent component analysis.

PubMed

Funane, Tsukasa; Atsumori, Hirokazu; Katura, Takusige; Obata, Akiko N; Sato, Hiroki; Tanikawa, Yukari; Okada, Eiji; Kiguchi, Masashi

2014-01-15

To quantify the effect of absorption changes in the deep tissue (cerebral) and shallow tissue (scalp, skin) layers on functional near-infrared spectroscopy (fNIRS) signals, a method using multi-distance (MD) optodes and independent component analysis (ICA), referred to as the MD-ICA method, is proposed. In previous studies, when the signal from the shallow tissue layer (shallow signal) needs to be eliminated, it was often assumed that the shallow signal had no correlation with the signal from the deep tissue layer (deep signal). In this study, no relationship between the waveforms of deep and shallow signals is assumed, and instead, it is assumed that both signals are linear combinations of multiple signal sources, which allows the inclusion of a "shared component" (such as systemic signals) that is contained in both layers. The method also assumes that the partial optical path length of the shallow layer does not change, whereas that of the deep layer linearly increases along with the increase of the source-detector (S-D) distance. Deep- and shallow-layer contribution ratios of each independent component (IC) are calculated using the dependence of the weight of each IC on the S-D distance. Reconstruction of deep- and shallow-layer signals are performed by the sum of ICs weighted by the deep and shallow contribution ratio. Experimental validation of the principle of this technique was conducted using a dynamic phantom with two absorbing layers. Results showed that our method is effective for evaluating deep-layer contributions even if there are high correlations between deep and shallow signals. Next, we applied the method to fNIRS signals obtained on a human head with 5-, 15-, and 30-mm S-D distances during a verbal fluency task, a verbal working memory task (prefrontal area), a finger tapping task (motor area), and a tetrametric visual checker-board task (occipital area) and then estimated the deep-layer contribution ratio. To evaluate the signal separation performance of our method, we used the correlation coefficients of a laser-Doppler flowmetry (LDF) signal and a nearest 5-mm S-D distance channel signal with the shallow signal. We demonstrated that the shallow signals have a higher temporal correlation with the LDF signals and with the 5-mm S-D distance channel than the deep signals. These results show the MD-ICA method can discriminate between deep and shallow signals. Copyright © 2013 Elsevier Inc. All rights reserved.

Physics considerations in MV-CBCT multi-layer imager design.

PubMed

Hu, Yue-Houng; Fueglistaller, Rony; Myronakis, Marios E; Rottmann, Joerg; Wang, Adam; Shedlock, Daniel; Morf, Daniel; Baturin, Paul; Huber, Pascal; Star-Lack, Josh M; Berbeco, Ross I

2018-05-30

Megavoltage (MV) cone-beam computed tomography (CBCT) using an electronic portal imaging (EPID) offers advantageous features, including 3D mapping, treatment beam registration, high-z artifact suppression, and direct radiation dose calculation. Adoption has been slowed by image quality limitations and concerns about imaging dose. Developments in imager design, including pixelated scintillators, structured phosphors, inexpensive scintillation materials, and multi-layer imager (MLI) architecture have been explored to improve EPID image quality and reduce imaging dose. The present study employs a hybrid Monte Carlo and linear systems model to determine the effect of detector design elements, such as multi-layer architecture and scintillation materials. We follow metrics of image quality including modulation transfer function (MTF) and noise power spectrum (NPS) from projection images to 3D reconstructions to in-plane slices and apply a task based figure-of-merit, the ideal observer signal-to-noise ratio (d') to determine the effect of detector design on object detectability. Generally, detectability was limited by detector noise performance. Deploying an MLI imager with a single scintillation material for all layers yields improvement in noise performance and d' linear with the number of layers. In general, improving x-ray absorption using thicker scintillators results in improved DQE(0). However, if light yield is low, performance will be affected by electronic noise at relatively high doses, resulting in rapid image quality degradation. Maximizing image quality in a heterogenous MLI detector (i.e. multiple different scintillation materials) is most affected by limiting imager noise. However, while a second-order effect, maximizing total spatial resolution of the MLI detector is a balance between the intensity contribution of each layer against its individual MTF. So, while a thinner scintillator may yield a maximal individual-layer MTF, its quantum efficiency will be relatively low in comparison to a thicker scintillator and thus, intensity contribution may be insufficient to noticeably improve the total detector MTF. © 2018 Institute of Physics and Engineering in Medicine.

78 FR 13755 - Notice of Receipt of Petition for Decision That Nonconforming 2003 Jeep Wrangler Multi-Purpose...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-28

... System, 114 Theft Protection, 116 Motor Vehicle Brake Fluids, 118 Power-Operated Window, Partition, and...: Replacement of the instrument cluster with a U.S.-model component with inscription of the word ``brake'' on the brake failure warning light as well as reading speed in mph. Standard No. 108 Lamps, Reflective...

Light weight fire resistant graphite composites

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.; Hsu, M. T. S.

1986-01-01

Composite structures with a honeycomb core and characterized by lightweight and excellent fire resistance are provided. These sandwich structures employ facesheets made up of bismaleimide-vinyl styrylpyridine copolymers with fiber reinforcement such as carbon fiber reinforcement. In preferred embodiments the facesheets are over layered with a decorative film. The properties of these composites make them attractive materials of construction aircraft and spacecraft.

A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species

PubMed Central

Onoda, Yusuke; Schieving, Feike; Anten, Niels P. R.

2015-01-01

Plant leaves commonly exhibit a thin, flat structure that facilitates a high light interception per unit mass, but may increase risks of mechanical failure when subjected to gravity, wind and herbivory as well as other stresses. Leaf laminas are composed of thin epidermis layers and thicker intervening mesophyll layers, which resemble a composite material, i.e. sandwich structure, used in engineering constructions (e.g. airplane wings) where high bending stiffness with minimum weight is important. Yet, to what extent leaf laminas are mechanically designed and behave as a sandwich structure remains unclear. To resolve this issue, we developed and applied a novel method to estimate stiffness of epidermis- and mesophyll layers without separating the layers. Across a phylogenetically diverse range of 36 angiosperm species, the estimated Young’s moduli (a measure of stiffness) of mesophyll layers were much lower than those of the epidermis layers, indicating that leaf laminas behaved similarly to efficient sandwich structures. The stiffness of epidermis layers was higher in evergreen species than in deciduous species, and strongly associated with cuticle thickness. The ubiquitous nature of sandwich structures in leaves across studied species suggests that the sandwich structure has evolutionary advantages as it enables leaves to be simultaneously thin and flat, efficiently capturing light and maintaining mechanical stability under various stresses. PMID:25675956

Assessing dorsal scute microchemistry for reconstruction of shortnose sturgeon life histories

USGS Publications Warehouse

Altenritter, Matthew E.; Kinnison, Michael T.; Zydlewski, Gayle B.; Secor, David H.; Zydlewski, Joseph D.

2015-01-01

The imperiled status of sturgeons worldwide places priority on the identification and protection of critical habitats. We assessed the micro-structural and micro-chemical scope for a novel calcified structure, dorsal scutes, to be used for reconstruction of past habitat use and group separation in shortnose sturgeon (Acipenser brevirostrum). Dorsal scutes contained a dual-layered structure composed of a thin multi-layered translucent zone lying dorsally above a thicker multi-layered zone. Banding in the thick multi-layered zone correlated strongly with pectoral fin spine annuli supporting the presence of chronological structuring that could contain a chemical record of past environmental exposure. Trace element profiles (Sr:Ca), collected using both wavelength dispersive electron microprobe analysis and laser ablation inductively coupled mass spectrometry, suggest scutes record elemental information useful for tracing transitions between freshwater and marine environments. Moreover, mirror-image like Sr:Ca profiles were observed across the dual-zone structuring of the scute that may indicate duplication of the microchemical profile in a single structure. Additional element:calcium ratios measured in natal regions of dorsal scutes (Ba:Ca, Mg:Ca) suggest the potential for further refinement of techniques for identification of river systems of natal origin. In combination, our results provide proof of concept that dorsal scutes possess the necessary properties to be used as structures for reconstructions of past habitat use in sturgeons. Importantly, scutes may be collected non-lethally and with less injury than current structures, like otoliths and fin spines, affording an opportunity for broader application of microchemical techniques.

Microscale Soft Patterning for Solution Processable Metal Oxide Thin Film Transistors.

PubMed

Jung, Sang Wook; Chae, Soo Sang; Park, Jee Ho; Oh, Jin Young; Bhang, Suk Ho; Baik, Hong Koo; Lee, Tae Il

2016-03-23

We introduce a microscale soft pattering (MSP) route utilizing contact printing of chemically inert sub-nanometer thick low molecular weight (LMW) poly(dimethylsiloxane) (PDMS) layers. These PDMS layers serve as a release agent layer between the n-type Ohmic metal and metal oxide semiconductors (MOSs) and provide a layer that protects the MOS from water in the surrounding environment. The feasibility of our MSP route was experimentally demonstrated by fabricating solution processable In2O3, IZO, and IGZO TFTs with aluminum (Al), a typical n-type Ohmic metal. We have demonstrated patterning gaps as small as 13 μm. The TFTs fabricated using MSP showed higher field-effect-mobility and lower hysteresis in comparison with those made using conventional photolithography.

MAC layer security issues in wireless mesh networks

NASA Astrophysics Data System (ADS)

Reddy, K. Ganesh; Thilagam, P. Santhi

2016-03-01

Wireless Mesh Networks (WMNs) have emerged as a promising technology for a broad range of applications due to their self-organizing, self-configuring and self-healing capability, in addition to their low cost and easy maintenance. Securing WMNs is more challenging and complex issue due to their inherent characteristics such as shared wireless medium, multi-hop and inter-network communication, highly dynamic network topology and decentralized architecture. These vulnerable features expose the WMNs to several types of attacks in MAC layer. The existing MAC layer standards and implementations are inadequate to secure these features and fail to provide comprehensive security solutions to protect both backbone and client mesh. Hence, there is a need for developing efficient, scalable and integrated security solutions for WMNs. In this paper, we classify the MAC layer attacks and analyze the existing countermeasures. Based on attacks classification and countermeasures analysis, we derive the research directions to enhance the MAC layer security for WMNs.

A long-term ultrahigh temperature application of layered silicide coated Nb alloy in air

NASA Astrophysics Data System (ADS)

Sun, Jia; Fu, Qian-Gang; Li, Tao; Wang, Chen; Huo, Cai-Xia; Zhou, Hong; Yang, Guan-Jun; Sun, Le

2018-05-01

Nb-based alloy possessed limited application service life at ultrahigh temperature (>1400 °C) in air even taking the effective protective coating strategy into consideration for last decades. In this work a long duration of above 128 h at 1500 °C in air was successfully achieved on Nb-based alloy thanked to multi-layered silicide coating. Through optimizing interfaces, the MoSi2/NbSi2 silicide coating with Al2O3-adsorbed-particles layer exhibited three-times higher of oxidation resistance capacity than the one without it. In MoSi2-Al2O3-NbSi2 multilayer coating, the Al2O3-adsorbed-particles layer playing as an element-diffusion barrier role, as well as the formed porous Nb5Si3 layer as a stress transition zone, contributed to the significant improvement.

Shining Light on Skin Pigmentation: The Darker and the Brighter Side of Effects of UV Radiation†

PubMed Central

Maddodi, Nityanand; Jayanthy, Ashika; Setaluri, Vijayasaradhi

2012-01-01

The term barrier function as applied to human skin often connotes the physical properties of this organ that provide protection from its surrounding environment. This term does not generally include skin pigmentation. However, skin pigmentation, which is the result of melanin produced in melanocytes residing the basal layer of the skin and exported to the keratinocytes in the upper layers, serves equally important protective function. Indeed, changes in skin pigmentation are often the most readily recognized indicators of exposure of skin to damaging agents, especially to natural and artificial radiation in the environment. Several recent studies have shed new light on a) the mechanisms of involved in selective effects of subcomponents of UV radiation on human skin pigmentation and b) the interactive influences between keratinocytes and melanocytes, acting as ‘epidermal melanin unit’, that manifest as changes in skin pigmentation in response to exposure to various forms of radiation. This article provides a concise review of our current understanding of the effects of the non-ionizing solar radiation, at cellular and molecular levels, on human skin pigmentation. PMID:22404235

Design and implementation of atmospheric multi-parameter sensor for UAVs

NASA Astrophysics Data System (ADS)

Yu, F.; Zhao, Y.; Chen, G.; Liu, Y.; Han, Y.

2017-12-01

With the rapid development of industry and the increase of cars in developing countries, air pollutants have caused a series of environmental issues such as haze and smog. However, air pollution is a process of surface-to-air mass exchange, and various kinds of atmospheric factors have close association with aerosol concentration, such as temperature, humidity, etc. Vertical distributions of aerosol in the region provide an important clue to reveal the exchange mechanism in the atmosphere between atmospheric boundary layer and troposphere. Among the various kinds of flying platforms, unmanned aerial vehicles (UAVs) shows more advantages in vertical measurement of aerosol owned to its flexibility and low cost. However, only few sensors could be mounted on the UAVs because of the limited size and power requirement. Here, a light-weight, low-power atmospheric multi-parameter sensor (AMPS) is proposed and could be mounted on several kinds of UAV platforms. The AMPS integrates multi-sensors, which are the laser aerosol particle sensor, the temperature probe, the humidity probe and the pressure probe, in order to simultaneously sample the vertical distribution characters of aerosol particle concentration, temperature, relative humidity and atmospheric pressure. The data from the sensors are synchronized by a proposed communication mechanism based on GPS. Several kinds of housing are designed to accommodate the different payload requirements of UAVs in size and weight. The experiments were carried out with AMPS mounted on three kinds of flying platforms. The results shows that the power consumption is less than 1.3 W, with relatively high accuracy in temperature (±0.1°C), relative humidity (±0.8%RH), PM2.5 (<20%) and PM10 (<20%). Vertical profiles of PM2.5 and PM10 concentrations were observed simultaneously by the AMPS three times every day in five days. The results revealed the significant correlation between the aerosol particle concentration and atmospheric parameters. With low cost and flexibility, AMPS for UAVs provides an effective way to explore the properties of aerosol vertical distribution, and to monitor air pollutants flexibly.

Study on copper phthalocyanine and perylene-based ambipolar organic light-emitting field-effect transistors produced using neutral beam deposition method

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

Kim, Dae-Kyu; Oh, Jeong-Do; Shin, Eun-Sol

2014-04-28

The neutral cluster beam deposition (NCBD) method has been applied to the production and characterization of ambipolar, heterojunction-based organic light-emitting field-effect transistors (OLEFETs) with a top-contact, multi-digitated, long-channel geometry. Organic thin films of n-type N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide and p-type copper phthalocyanine were successively deposited on the hydroxyl-free polymethyl-methacrylate (PMMA)-coated SiO{sub 2} dielectrics using the NCBD method. Characterization of the morphological and structural properties of the organic active layers was performed using atomic force microscopy and X-ray diffraction. Various device parameters such as hole- and electron-carrier mobilities, threshold voltages, and electroluminescence (EL) were derived from the fits of the observed current-voltage andmore » current-voltage-light emission characteristics of OLEFETs. The OLEFETs demonstrated good field-effect characteristics, well-balanced ambipolarity, and substantial EL under ambient conditions. The device performance, which is strongly correlated with the surface morphology and the structural properties of the organic active layers, is discussed along with the operating conduction mechanism.« less

Lightweight protective clothing for the safe handling of high-intensity pressurized lamps

NASA Technical Reports Server (NTRS)

Ewashinka, J. G.

1975-01-01

Five commercially available clothing materials, selected for their high cutting resistance, high strength, light weight and pliability, were tested by exposing them to exploding lamps located less than 60 cm (2 ft) away. Face shield material tested initially was commercial high-strength polycarbonate plastic.

Long-distance transmission of light in a scintillator-based radiation detector

DOEpatents

Dowell, Jonathan L.; Talbott, Dale V.; Hehlen, Markus P.

2017-07-11

Scintillator-based radiation detectors capable of transmitting light indicating the presence of radiation for long distances are disclosed herein. A radiation detector can include a scintillator layer and a light-guide layer. The scintillator layer is configured to produce light upon receiving incident radiation. The light-guide layer is configured to receive light produced by the scintillator layer and either propagate the received light through the radiation detector or absorb the received light and emit light, through fluorescence, that is propagated through the radiation detector. A radiation detector can also include an outer layer partially surrounding the scintillator layer and light-guide layer. The index of refraction of the light-guide layer can be greater than the index of refraction of adjacent layers.

Biochemical component identification by plasmonic improved whispering gallery mode optical resonance based sensor

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

2014-05-01

Experimental data on detection and identification of variety of biochemical agents, such as proteins, microelements, antibiotic of different generation etc. in both single and multi component solutions under varied in wide range concentration analyzed on the light scattering parameters of whispering gallery mode optical resonance based sensor are represented. Multiplexing on parameters and components has been realized using developed fluidic sensor cell with fixed in adhesive layer dielectric microspheres and data processing. Biochemical component identification has been performed by developed network analysis techniques. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis. Novel technique based on optical resonance on microring structures, plasmon resonance and identification tools has been developed. To improve a sensitivity of microring structures microspheres fixed by adhesive had been treated previously by gold nanoparticle solution. Another technique used thin film gold layers deposited on the substrate below adhesive. Both biomolecule and nanoparticle injections caused considerable changes of optical resonance spectra. Plasmonic gold layers under optimized thickness also improve parameters of optical resonance spectra. Biochemical component identification has been also performed by developed network analysis techniques both for single and for multi component solution. So advantages of plasmon enhancing optical microcavity resonance with multiparameter identification tools is used for development of a new platform for ultra sensitive label-free biomedical sensor.

Operationalising resilience to drought: Multi-layered safety for flooding applied to droughts

NASA Astrophysics Data System (ADS)

Rijke, Jeroen; Smith, Jennifer Vessels; Gersonius, Berry; van Herk, Sebastiaan; Pathirana, Assela; Ashley, Richard; Wong, Tony; Zevenbergen, Chris

2014-11-01

This paper sets out a way of thinking about how to prepare for and respond to droughts in a holistic way using a framework developed for managing floods. It shows how the multi-layered safety (MLS) approach for flood resilience can be utilised in the context of drought in a way that three layers of intervention can be distinguished for operationalising drought resilience: (1) protection against water shortage through augmentation and diversification of water supplies; (2) prevention of damage in case of water shortage through increased efficiency of water use and timely asset maintenance; (3) preparedness for future water shortages through mechanisms to reduce the use of water and adopt innovative water technologies. Application of MLS to the cities of Adelaide, Melbourne and Sydney shows that recent water reforms in these cities were primarily focused on protection measures that aim to reduce the hazard source or exposure to insufficient water supplies. Prevention and preparedness measures could be considered in defining interventions that aim to further increase the drought resilience of these cities. Although further research is needed, the application suggests that MLS can be applied to the context of drought risk management. The MLS framework can be used to classify the suite of plans deployed by a city to manage future drought risks and can be considered a planning tool to identify opportunities for increasing the level of redundancy and hence resilience of the drought risk management system.

Anatomy of an entry vehicle experiment

NASA Technical Reports Server (NTRS)

Eide, D. G.; Wurster, K. E.; Helms, V. T.; Ashby, G. C.

1981-01-01

The anatomy and evolution of a simple small-scale unmanned entry vehicle is described that is delivered to orbit by the shuttle and entered into the atmosphere from orbit to acquire flight data to improve our knowledge of boundary-layer behavior and evaluate advanced thermal protection systems. The anatomy of the experiment includes the justification for the experiments, instrumentation, configuration, material, and operational needs, and the translation of these needs into a configuration, weight statement, aerodynamics, program cost, and trajectory. Candidates for new instrumentation development are also identified for nonintrusive measurements of the boundary-layer properties.

Multilayer Impregnated Fibrous Thermal Insulation Tiles

NASA Technical Reports Server (NTRS)

Tran, Huy K.; Rasky, Daniel J.; Szalai, Christine e.; Hsu, Ming-ta; Carroll, Joseph A.

2007-01-01

The term "secondary polymer layered impregnated tile" ("SPLIT") denotes a type of ablative composite-material thermal- insulation tiles having engineered, spatially non-uniform compositions. The term "secondary" refers to the fact that each tile contains at least two polymer layers wherein endothermic reactions absorb considerable amounts of heat, thereby helping to prevent overheating of an underlying structure. These tiles were invented to afford lighter-weight alternatives to the reusable thermal-insulation materials heretofore variously used or considered for use in protecting the space shuttles and other spacecraft from intense atmospheric-entry heating.

Suppression of HSP27 Restores Retinal Function and Protects Photoreceptors From Apoptosis in a Light-Induced Retinal Degeneration Animal Model.

PubMed

Chien, Chih-Cheng; Huang, Chi-Jung; Tien, Lu-Tai; Cheng, Yu-Che; Ke, Chia-Ying; Lee, Yih-Jing

2017-06-01

We used a light-induced retinal degeneration animal model to investigate possible roles of heat shock protein 27 (HSP27) in retinal/photoreceptor protection. Sprague-Dawley rats were used for the light-induced retinal degeneration animal model. The histology of eye sections was observed for morphologic changes in the retina. Cell apoptosis was examined in each group using the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and electroretinography was used to evaluate retinal function. Protein and mRNA expression levels of different retinal cell markers were also detected through immunofluorescence staining, Western blotting, and real-time PCR. The thickness of the outer nuclear layer significantly decreased after 7-day light exposure. Moreover, we injected a viral vector for silencing HSP27 expression into the eyes and observed that photoreceptors were better preserved in the HSP27-suppressed (sHSP27) retina 2 weeks after injection. HSP27 suppression also reduced retinal cell apoptosis caused by light exposure. In addition, the loss of retinal function caused by light exposure was reversed on suppressing HSP27 expression. We subsequently found that the expression of the Rho gene and immunofluorescence staining of rhodopsin and arrestin (cell markers for photoreceptors) increased in sHSP27-treated retinas. HSP27 suppression did not affect the survival of ganglion and amacrine cells. Retinal cell apoptosis and functional loss were observed after 7-day light exposure. However, in the following 2 weeks after light exposure, HSP27 suppression may initiate a protective effect for retinal cells, particularly photoreceptors, from light-induced retinal degeneration.

Realizing a facile and environmental-friendly fabrication of high-performance multi-crystalline silicon solar cells by employing ZnO nanostructures and an Al2O3 passivation layer

PubMed Central

Chen, Hong-Yan; Lu, Hong-Liang; Sun, Long; Ren, Qing-Hua; Zhang, Hao; Ji, Xin-Ming; Liu, Wen-Jun; Ding, Shi-Jin; Yang, Xiao-Feng; Zhang, David Wei

2016-01-01

Nowadays, the multi-crystalline silicon (mc-Si) solar cells dominate the photovoltaic industry. However, the current acid etching method on mc-Si surface used by firms can hardly suppress the average reflectance value below 25% in the visible light spectrum. Meanwhile, the nitric acid and the hydrofluoric contained in the etching solution is both environmental unfriendly and highly toxic to human. Here, a mc-Si solar cell based on ZnO nanostructures and an Al2O3 spacer layer is demonstrated. The eco-friendly fabrication is realized by low temperature atomic layer deposition of Al2O3 layer as well as ZnO seed layer. Moreover, the ZnO nanostructures are prepared by nontoxic and low cost hydro-thermal growth process. Results show that the best passivation quality of the n+ -type mc-Si surface can be achieved by balancing the Si dangling bond saturation level and the negative charge concentration in the Al2O3 film. Moreover, the average reflectance on cell surface can be suppressed to 8.2% in 400–900 nm range by controlling the thickness of ZnO seed layer. With these two combined refinements, a maximum solar cell efficiency of 15.8% is obtained eventually. This work offer a facile way to realize the environmental friendly fabrication of high performance mc-Si solar cells. PMID:27924911

Realizing a facile and environmental-friendly fabrication of high-performance multi-crystalline silicon solar cells by employing ZnO nanostructures and an Al2O3 passivation layer

NASA Astrophysics Data System (ADS)

Chen, Hong-Yan; Lu, Hong-Liang; Sun, Long; Ren, Qing-Hua; Zhang, Hao; Ji, Xin-Ming; Liu, Wen-Jun; Ding, Shi-Jin; Yang, Xiao-Feng; Zhang, David Wei

2016-12-01

Nowadays, the multi-crystalline silicon (mc-Si) solar cells dominate the photovoltaic industry. However, the current acid etching method on mc-Si surface used by firms can hardly suppress the average reflectance value below 25% in the visible light spectrum. Meanwhile, the nitric acid and the hydrofluoric contained in the etching solution is both environmental unfriendly and highly toxic to human. Here, a mc-Si solar cell based on ZnO nanostructures and an Al2O3 spacer layer is demonstrated. The eco-friendly fabrication is realized by low temperature atomic layer deposition of Al2O3 layer as well as ZnO seed layer. Moreover, the ZnO nanostructures are prepared by nontoxic and low cost hydro-thermal growth process. Results show that the best passivation quality of the n+ -type mc-Si surface can be achieved by balancing the Si dangling bond saturation level and the negative charge concentration in the Al2O3 film. Moreover, the average reflectance on cell surface can be suppressed to 8.2% in 400-900 nm range by controlling the thickness of ZnO seed layer. With these two combined refinements, a maximum solar cell efficiency of 15.8% is obtained eventually. This work offer a facile way to realize the environmental friendly fabrication of high performance mc-Si solar cells.

Calibration of PVDF Film Transducers for the Cavitation Impact Measurement

NASA Astrophysics Data System (ADS)

Hujer, Jan; Müller, Miloš

2018-06-01

This paper describes investigation of the influence of the protective layer thickness on the calibration sensitivity of PVDF films sensors for the cavitation impacts measurements. The PVDF film sensor is casted into an aluminium block. The drop ball method is used for the measurement of the relation between impact force and the voltage detected on the PVDF film sensor. The calibration constants are measured for three different protective layers thicknesses. Five different ball weights for 400 mm drop height are used to reach the required impact force range. The ball positions for the evaluation of the impact force are measured with a high speed camera. The voltage signal detected on the PVDF film clamps was measured with a high speed digitizer. The measured signals are analysed in LabVIEW Signal Express.

Sources, control, and effects of noise from aircraft propellers and rotors. [noise prediction (aircraft

NASA Technical Reports Server (NTRS)

Mixson, J. S.; Greene, G. C.; Dempsey, T. K.

1981-01-01

Source noise predictions are compared with measurements for conventional low-speed propellers, for new high speed propellers (propfans), and for a helicopter. Results from a light aircraft demonstration program are described, indicating that about 5-dB reduction of flyover noise can be obtained without significant performance penalty. Sidewall design studies are described for interior noise control in light general aviation aircraft and in large transports using propfan propulsion. The weight of the added acoustic treatment is estimated and tradeoffs between weight and noise reduction are discussed. A laboratory study of passenger response to combined broadband and tonal propeller like noise is described. Subject discomfort ratings of combined tone broadband noises are compared with ratings of broadband (boundary layer) noise alone, and the relative importance of the propeller tones is examined.

Predicting transmittance spectra of electrophotographic color prints

NASA Astrophysics Data System (ADS)

Mourad, Safer; Emmel, Patrick; Hersch, Roger D.

2000-12-01

For dry toner electrophotographic color printers, we present a numerical simulation model describing the color printer responses based on a physical characterization of the different electrophotographic process steps. The proposed model introduces a Cross Transfer Efficiency designed to predict the color transmittance spectra of multi-color prints by taking into account the transfer influence of each deposited color toner layer upon the other layers. The simulation model leads to a better understanding of the factors that have an impact on printing quality. In order to avoid the additional optical non-linearities produced by light reflection on paper, we have limited the present investigation to transparency prints. The proposed model succeeded to predict the transmittance spectra of printed wedges combining two color toner layers with a mean deviation less than CIE-LAB (Delta) E equals 2.5.

Scintillating fibres coupled to silicon photomultiplier prototypes for fast beam monitoring and thin timing detectors

NASA Astrophysics Data System (ADS)

Papa, A.; Kettle, P.-R.; Ripiccini, E.; Rutar, G.

2016-07-01

Several scintillating fibre prototypes (single- and double-layers) made of 250 μm multi-clad square fibres coupled to silicon photomultiplier have been studied using electrons, positrons and muons at different energies. Current measurements show promising results: already for a single fibre layer and minimum ionizing particles we obtain a detection efficiency ≥ 95 % (mean collected light/fibre ≈ 8 phe), a timing resolution of 550 ps/fibre and a foreseen spatial resolution < 100 μm, based on the achieved negligible optical cross-talk between fibres (< 1 %). We will also discuss the performances of a double-layer staggered prototype configuration, for which a full detection efficiency (≥ 99 %) has been measured together with a timing resolution of ≈ 400 ps for double hit events.

Controlled surface oxidation of multi-layered graphene anode to increase hole injection efficiency in organic electronic devices

NASA Astrophysics Data System (ADS)

Han, Tae-Hee; Kwon, Sung-Joo; Seo, Hong-Kyu; Lee, Tae-Woo

2016-03-01

Ultraviolet ozone (UVO) surface treatment of graphene changes its sp2-hybridized carbons to sp3-bonded carbons, and introduces oxygen-containing components. Oxidized graphene has a finite energy band gap, so UVO modification of the surface of a four-layered graphene anode increases its surface ionization potential up to ∼5.2 eV and improves the hole injection efficiency (η) in organic electronic devices by reducing the energy barrier between the graphene anode and overlying organic layers. By controlling the conditions of the UVO treatment, the electrical properties of the graphene can be tuned to improve η. This controlled surface modification of the graphene will provide a way to achieve efficient and stable flexible displays and solid-state lighting.

Encapsulation of organic light emitting diodes

NASA Astrophysics Data System (ADS)

Visweswaran, Bhadri

Organic Light Emitting Diodes (OLEDs) are extremely attractive candidates for flexible display and lighting panels due to their high contrast ratio, light weight and flexible nature. However, the materials in an OLED get oxidized by extremely small quantities of atmospheric moisture and oxygen. To obtain a flexible OLED device, a flexible thin-film barrier encapsulation with low permeability for water is necessary. Water permeates through a thin-film barrier by 4 modes: microcracks, contaminant particles, along interfaces, and through the bulk of the material. We have developed a flexible barrier film made by Plasma Enhanced Chemical Vapor Deposition (PECVD) that is devoid of any microcracks. In this work we have systematically reduced the permeation from the other three modes to come up with a barrier film design for an operating lifetime of over 10 years. To provide quantitative feedback during barrier material development, techniques for measuring low diffusion coefficient and solubility of water in a barrier material have been developed. The mechanism of water diffusion in the barrier has been identified. From the measurements, we have created a model for predicting the operating lifetime from accelerated tests when the lifetime is limited by bulk diffusion. To prevent the particle induced water permeation, we have encapsulated artificial particles and have studied their cross section. A three layer thin-film that can coat a particle at thicknesses smaller than the particle diameter is identified. It is demonstrated to protect a bottom emission OLED device that was contaminated with standard sized glass beads. The photoresist and the organic layers below the barrier film causes sideways permeation that can reduce the lifetime set by permeation through the bulk of the barrier. To prevent the sideways permeation, an impermeable inorganic grid made of the same barrier material is designed. The reduction in sideways permeation due to the impermeable inorganic grid is demonstrated in an encapsulated OLED. In this work, we have dealt with three permeation mechanisms and shown solution to each of them. These steps give us reliable flexible encapsulation that has a lifetime of greater than 10 years.

Optical switch using Risley prisms

DOEpatents

Sweatt, William C.; Christenson, Todd R.

2003-04-15

An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

Optical Switch Using Risley Prisms

DOEpatents

Sweatt, William C.; Christenson, Todd R.

2005-02-22

An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

High temperature interface superconductivity

DOE PAGES

Gozar, A.; Bozovic, I.

2016-01-20

High-T c superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T c Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed.more » Here, we conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.« less

Polyethers with pendent phenylvinyl substituted carbazole rings as polymers for hole transporting layers of OLEDs

NASA Astrophysics Data System (ADS)

Griniene, R.; Liu, L.; Tavgeniene, D.; Sipaviciute, D.; Volyniuk, D.; Grazulevicius, J. V.; Xie, Z.; Zhang, B.; Leduskrasts, K.; Grigalevicius, S.

2016-01-01

Polyethers containing pendent 3-(2-phenylvinyl)carbazole moieties have been synthesized by the multi-step synthetic routes. Full characterization of their structures is presented. The polymers represent materials of high thermal stability with initial thermal degradation temperatures exceeding 370 °C. The glass transition temperatures of the amorphous materials were in the range of 56-658 °C. The electron photoemission spectra of thin layers of the polymers showed ionization potentials of about 5.6 eV. Hole-transporting properties of the polymeric materials were tested in the structures of organic light emitting diodes with Alq3 as the green emitter and electron transporting layer. The device containing hole-transporting layers of poly{9-[6-(3-methyloxetan-3-ylmethoxy)hexyl]-3-(2-phenylvinyl)carbazole} exhibited the best overall performance with a maximum photometric efficiency of about 4.0 cd/A and maximum brightness exceeding 6430 cd/m2.

On-Orbit Teflon(trademark) FEP Degradation

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline A.; Hansen, Patricia A.; Dever, Joyce A.

1998-01-01

During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon(trademark) FEP (fluorinated ethylene propylene), used as the outer layer of the multi-layer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon(trademark) FEP sample evaluation and additional testing of pristine Teflon(trademark) FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations, and that the damage increased with the combined total dose of electrons, protons, UV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the Teflon(trademark) FEP.

Light-stress avoidance mechanisms in a Sphagnum-dominated wet coastal Arctic tundra ecosystem in Alaska.

PubMed

Zona, D; Oechel, Walter C; Richards, James H; Hastings, Steven; Kopetz, Irene; Ikawa, Hiroki; Oberbauer, Steven

2011-03-01

The Arctic experiences a high-radiation environment in the summer with 24-hour daylight for more than two months. Damage to plants and ecosystem metabolism can be muted by overcast conditions common in much of the Arctic. However, with climate change, extreme dry years and clearer skies could lead to the risk of increased photoxidation and photoinhibition in Arctic primary producers. Mosses, which often exceed the NPP of vascular plants in Arctic areas, are often understudied. As a result, the effect of specific environmental factors, including light, on these growth forms is poorly understood. Here, we investigated net ecosystem exchange (NEE) at the ecosystem scale, net Sphagnum CO2 exchange (NSE), and photoinhibition to better understand the impact of light on carbon exchange from a moss-dominated coastal tundra ecosystem during the summer season 2006. Sphagnum photosynthesis showed photoinhibition early in the season coupled with low ecosystem NEE. However, later in the season, Sphagnum maintained a significant CO2 uptake, probably for the development of subsurface moss layers protected from strong radiation. We suggest that the compact canopy structure of Sphagnum reduces light penetration to the subsurface layers of the moss mat and thereby protects the active photosynthetic tissues from damage. This stress avoidance mechanism allowed Sphagnum to constitute a significant percentage (up to 60%) of the ecosystem net daytime CO2 uptake at the end of the growing season despite the high levels of radiation experienced.

Process Integration and Optimization of ICME Carbon Fiber Composites for Vehicle Lightweighting: A Preliminary Development

DOE PAGES

Xu, Hongyi; Li, Yang; Zeng, Danielle

2017-01-02

Process integration and optimization is the key enabler of the Integrated Computational Materials Engineering (ICME) of carbon fiber composites. In this paper, automated workflows are developed for two types of composites: Sheet Molding Compounds (SMC) short fiber composites, and multi-layer unidirectional (UD) composites. For SMC, the proposed workflow integrates material processing simulation, microstructure representation volume element (RVE) models, material property prediction and structure preformation simulation to enable multiscale, multidisciplinary analysis and design. Processing parameters, microstructure parameters and vehicle subframe geometry parameters are defined as the design variables; the stiffness and weight of the structure are defined as the responses. Formore » multi-layer UD structure, this work focuses on the discussion of different design representation methods and their impacts on the optimization performance. Challenges in ICME process integration and optimization are also summarized and highlighted. Two case studies are conducted to demonstrate the integrated process and its application in optimization.« less

Exaggeration and suppression of iridescence: the evolution of two-dimensional butterfly structural colours

PubMed Central

Wickham, Shelley; Large, Maryanne C.J; Poladian, Leon; Jermiin, Lars S

2005-01-01

Many butterfly species possess ‘structural’ colour, where colour is due to optical microstructures found in the wing scales. A number of such structures have been identified in butterfly scales, including three variations on a simple multi-layer structure. In this study, we optically characterize examples of all three types of multi-layer structure, as found in 10 species. The optical mechanism of the suppression and exaggeration of the angle-dependent optical properties (iridescence) of these structures is described. In addition, we consider the phylogeny of the butterflies, and are thus able to relate the optical properties of the structures to their evolutionary development. By applying two different types of analysis, the mechanism of adaptation is addressed. A simple parsimony analysis, in which all evolutionary changes are given an equal weighting, suggests convergent evolution of one structure. A Dollo parsimony analysis, in which the evolutionary ‘cost’ of losing a structure is less than that of gaining it, implies that ‘latent’ structures can be reused. PMID:16849221

Multi-layer assemblies with predetermined stress profile and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor); Phillips, Stephen M. (Inventor)

2003-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations.

Integrated neuron circuit for implementing neuromorphic system with synaptic device

NASA Astrophysics Data System (ADS)

Lee, Jeong-Jun; Park, Jungjin; Kwon, Min-Woo; Hwang, Sungmin; Kim, Hyungjin; Park, Byung-Gook

2018-02-01

In this paper, we propose and fabricate Integrate & Fire neuron circuit for implementing neuromorphic system. Overall operation of the circuit is verified by measuring discrete devices and the output characteristics of the circuit. Since the neuron circuit shows asymmetric output characteristic that can drive synaptic device with Spike-Timing-Dependent-Plasticity (STDP) characteristic, the autonomous weight update process is also verified by connecting the synaptic device and the neuron circuit. The timing difference of the pre-neuron and the post-neuron induce autonomous weight change of the synaptic device. Unlike 2-terminal devices, which is frequently used to implement neuromorphic system, proposed scheme of the system enables autonomous weight update and simple configuration by using 4-terminal synapse device and appropriate neuron circuit. Weight update process in the multi-layer neuron-synapse connection ensures implementation of the hardware-based artificial intelligence, based on Spiking-Neural- Network (SNN).

Application of Viscoelastic Fracture Model and Non-uniform Crack Initiation at Clinically Relevant Notches in Crosslinked UHMWPE

PubMed Central

Sirimamilla, P. Abhiram; Furmanski, Jevan; Rimnac, Clare M.

2012-01-01

The mechanism of crack initiation from a clinically relevant notch is not well-understood for crosslinked ultra high molecular weight polyethylene (UHMWPE) used in total joint replacement components. Static mode driving forces, rather than the cyclic mode conditions typically associated with fatigue processes, have been shown to drive crack propagation in this material. Thus, in this study, crack initiation in a notched specimen under a static load was investigated. A video microscope was used to monitor the notch surface of the specimen and crack initiation time was measured from the video by identifying the onset of crack initiation at the notch. Crack initiation was considered using a viscoelastic fracture theory. It was found that the mechanism of crack initiation involved both single layer and a distributed multi-layer phenomenon and that multi-layer crack initiation delayed the crack initiation time for all loading conditions examined. The findings of this study support that the viscoelastic fracture theory governs fracture mechanics in crosslinked UHMWPE. The findings also support that crack initiation from a notch in UHMWPE is a more complex phenomenon than treated by traditional fracture theories for polymers. PMID:23127638

Inferring strength and deformation properties of hot mix asphalt layers from the GPR signal: recent advances

NASA Astrophysics Data System (ADS)

Tosti, Fabio; Benedetto, Andrea; Bianchini Ciampoli, Luca; Adabi, Saba; Pajewski, Lara

2015-04-01

The great flexibility of ground-penetrating radar has led to consider worldwide this instrument as an effective and efficient geophysical tool in several fields of application. As far as pavement engineering is concerned, ground-penetrating radar is employed in a wide range of applications, including physical and geometrical evaluation of road pavements. Conversely, the mechanical characterization of pavements is generally inferred through traditional (e.g., plate bearing test method) or advanced non-destructive techniques (e.g., falling weight deflectometer). Nevertheless, measurements performed using these methods, inevitably turn out to be both much more time-consuming and low-significant whether compared with ground-penetrating radar's potentials. In such a framework, a mechanical evaluation directly coming from electromagnetic inspections could represent a real breakthrough in the field of road assets management. With this purpose, a ground-penetrating radar system with 600 MHz and 1600 MHz center frequencies of investigation and ground-coupled antennas was employed to survey a 4m×30m flexible pavement test site. The test area was marked by a regular grid mesh of 836 nodes, respectively spaced by a distance of 0.40 m alongside the horizontal and vertical axes. At each node, the elastic modulus was measured using a light falling weight deflectometer. Data processing has provided to reconstruct a 3-D matrix of amplitudes for the surveyed area, considering a depth of around 300 mm, in accord to the influence domain of the light falling weight deflectometer. On the other hand, deflectometric data were employed for both calibration and validation of a semi-empirical model by relating the amplitude of signal reflections through the media along fixed depths within the depth domain considered, and the Young's modulus of the pavement at the evaluated point. This statistically-based model is aimed at continuously taking into account alongside the depth of investigation, of both the different strength provision of each layer composing the hot mix asphalt pavement structure, and of the attenuation occurring to electromagnetic waves during their in-depth propagation. Promising results are achieved by matching modelled and measured elastic modulus data. This continuous statistically-based model enables to consider the whole set of information related to each single depth, in order to provide a more comprehensive prediction of the strength and deformation behavior of such a complex multi-layered medium. Amongst some further developments to be tackled in the near future, a model improvement could be reached through laboratory activities under controlled conditions and by adopting several frequency bandwidths suited for purposes. In addition, the perspective to compare electromagnetic data with mechanical measurements retrieved continuously, i.e., by means of specifically equipped lorries, could pave the way to considerable enhancements in this field of research. Acknowledgements - This work has benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

Space shuttle orbiter trimmed center-of-gravity extension study. Volume 3: Impact of retrofits for center-of-gravity extension on orbiter thermal-protection system

NASA Technical Reports Server (NTRS)

Dunavant, J. C.

1979-01-01

Heat transfer studies were conducted at Mach 10.3 on space shuttle orbiter models with the S-2 fillet and C-4 canard retrofit moldlines which were generated in aerodynamic and system design studies to increase the allowable c.g. range of the orbiter. Areas of orbiter most strongly affected were the sides where a shear layer which separated along the wing leading edge impinged. Analytical studies of the heating effect on the thermal-protection system were made which indicated that scar weight on the orbiter sides due to allowances for retrofits of the S-2 fillet and C-4 canard is small (less than about 90 kg (200 lbs) in comparison to the total weight of the retrofit).

Effects of white-tailed deer and invasive plants on the herb layer of suburban forests

PubMed Central

2017-01-01

Abstract Lack of hunting and predators and proximity to human communities make suburban forests prone to high deer abundance and non-native plant invasions. I investigated these likely drivers of community structure in the herb layers of six suburban forests in one region of New Jersey, USA. In 223 plots I assessed the herb layer response to 2.5 years with or without deer fencing and the early stage of invasion from seed additions of Microstegium vimineum, an invasive, annual grass. Non-native plants and herbaceous native plants were affected very little by fencing or M. vimineum invasion. In contrast, across all forests the combination of deer access and M. vimineum addition had a strongly negative effect on woody native percent cover. Forests differed in overall fencing effects on woody natives; their cover was greater in fenced plots in just three forests, suggesting greater deer pressure in those forests during the experiment. The early invasion by M. vimineum was greatest in two of these same forests, but was not influenced by fencing. Multi-group structural equation modelling compared two groups of forests that differed in vegetation abundance and other characteristics. It paralleled the results above and also showed no negative influence of non-native cover on native cover, even in the forests where non-native cover was greater. It identified a positive effect of light level on herb layer plants in the forests with less vegetation, and also revealed a positive effect of soil water potential (SWP) on non-native plants in the forests with more vegetation, which had higher SWP. These suburban forests within a common region varied widely in native and non-native herb layer abundance, the early success of M. vimineum invasion and the herb layer’s response to early invasion and protection from deer. PMID:29218140

Comparison of graphite, aluminum, and TransHab shielding material characteristics in a high-energy neutron field

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Huff, H.; Wilkins, R.; Thibeault, Sheila

2002-01-01

Space radiation transport models clearly show that low atomic weight materials provide a better shielding protection for interplanetary human missions than high atomic weight materials. These model studies have concentrated on shielding properties against charged particles. A light-weight, inflatable habitat module called TransHab was built and shown to provide adequate protection against micrometeoroid impacts and good shielding properties against charged particle radiation in the International Space Station orbits. An experiment using a tissue equivalent proportional counter, to study the changes in dose and lineal energy spectra with graphite, aluminum, and a TransHab build-up as shielding, was carried out at the Los Alamos Nuclear Science Center neutron facility. It is a continuation of a previous study using regolith and doped polyethylene materials. This paper describes the results and their comparison with the previous study. Published by Elsevier Science Ltd.

Analysis of self-assembly of S-layer protein slp-B53 from Lysinibacillus sphaericus.

PubMed

Liu, Jun; Falke, Sven; Drobot, Bjoern; Oberthuer, Dominik; Kikhney, Alexey; Guenther, Tobias; Fahmy, Karim; Svergun, Dmitri; Betzel, Christian; Raff, Johannes

2017-01-01

The formation of stable and functional surface layers (S-layers) via self-assembly of surface-layer proteins on the cell surface is a dynamic and complex process. S-layers facilitate a number of important biological functions, e.g., providing protection and mediating selective exchange of molecules and thereby functioning as molecular sieves. Furthermore, S-layers selectively bind several metal ions including uranium, palladium, gold, and europium, some of them with high affinity. Most current research on surface layers focuses on investigating crystalline arrays of protein subunits in Archaea and bacteria. In this work, several complementary analytical techniques and methods have been applied to examine structure-function relationships and dynamics for assembly of S-layer protein slp-B53 from Lysinibacillus sphaericus: (1) The secondary structure of the S-layer protein was analyzed by circular dichroism spectroscopy; (2) Small-angle X-ray scattering was applied to gain insights into the three-dimensional structure in solution; (3) The interaction with bivalent cations was followed by differential scanning calorimetry; (4) The dynamics and time-dependent assembly of S-layers were followed by applying dynamic light scattering; (5) The two-dimensional structure of the paracrystalline S-layer lattice was examined by atomic force microscopy. The data obtained provide essential structural insights into the mechanism of S-layer self-assembly, particularly with respect to binding of bivalent cations, i.e., Mg 2+ and Ca 2+ . Furthermore, the results obtained highlight potential applications of S-layers in the fields of micromaterials and nanobiotechnology by providing engineered or individual symmetric thin protein layers, e.g., for protective, antimicrobial, or otherwise functionalized surfaces.

Solid Waste Landfill Site Selection in the Sense of Environment Sensitive Sustainable Urbanization: Izmir, Turkey Case

NASA Astrophysics Data System (ADS)

TÜdeş, Şule; Kumlu, Kadriye Burcu Yavuz

2017-10-01

Each stage of the planning process should be based on the natural resource protection, in the sense of environmental sensitive and sustainable urban planning. Values, which are vital for the continuity of the life in the Earth, as soil, water, forest etc. should be protected from the undesired effects of the pollution and the other effects caused by the high urbanization levels. In this context, GIS-MCDM based solid waste landfill site selection is applied for Izmir, Turkey, where is a significant attraction place for tourism. As Multi criteria Decision Making (MCDM) technique, Analytical Hierarchy Process (AHP) is used. In this study, geological, tectonically and hydrological data, as well as agricultural land use, slope, distance to the settlement areas and the highways are used as inputs for AHP analysis. In the analysis stage, those inputs are rated and weighted. The weighted criteria are evaluated via GIS, by using weighted overlay tool. Therefore, an upper-scale analysis is conducted and a map, which shows the alternative places for the solid waste landfill sites, considering the environmental protection and evaluated in the context of environmental and urban criteria, are obtained.

Flexible Stoichiometry and Asymmetry of the PIDDosome Core Complex by Heteronuclear NMR Spectroscopy and Mass Spectrometry

PubMed Central

Nematollahi, Lily A.; Garza-Garcia, Acely; Bechara, Chérine; Esposito, Diego; Morgner, Nina; Robinson, Carol V.; Driscoll, Paul C.

2015-01-01

Homotypic death domain (DD)–DD interactions are important in the assembly of oligomeric signaling complexes such as the PIDDosome that acts as a platform for activation of caspase-2-dependent apoptotic signaling. The structure of the PIDDosome core complex exhibits an asymmetric three-layered arrangement containing five PIDD-DDs in one layer, five RAIDD-DDs in a second layer and an additional two RAIDD-DDs. We addressed complex formation between PIDD-DD and RAIDD-DD in solution using heteronuclear nuclear magnetic resonance (NMR) spectroscopy, nanoflow electrospray ionization mass spectrometry and size-exclusion chromatography with multi-angle light scattering. The DDs assemble into complexes displaying molecular masses in the range 130–158 kDa and RAIDD-DD:PIDD-DD stoichiometries of 5:5, 6:5 and 7:5. These data suggest that the crystal structure is representative of only the heaviest species in solution and that two RAIDD-DDs are loosely attached to the 5:5 core. Two-dimensional 1H,15N-NMR experiments exhibited signal loss upon complexation consistent with the formation of high-molecular-weight species. 13C-Methyl-transverse relaxation optimized spectroscopy measurements of the PIDDosome core exhibit signs of differential line broadening, cross-peak splitting and chemical shift heterogeneity that reflect the presence of non-equivalent sites at interfaces within an asymmetric complex. Experiments using a mutant RAIDD-DD that forms a monodisperse 5:5 complex with PIDD-DD show that the spectroscopic signature derives from the quasi- but non-exact equivalent environments of each DD. Since this characteristic was previously demonstrated for the complex between the DDs of CD95 and FADD, the NMR data for this system are consistent with the formation of a structure homologous to the PIDDosome core. PMID:25528640

Bioengineered silver nanoparticles as potent anti-corrosive inhibitor for mild steel in cooling towers.

PubMed

Narenkumar, Jayaraman; Parthipan, Punniyakotti; Madhavan, Jagannathan; Murugan, Kadarkarai; Marpu, Sreekar Babu; Suresh, Anil Kumar; Rajasekar, Aruliah

2018-02-01

Silver nanoparticle-aided enhancement in the anti-corrosion potential and stability of plant extract as ecologically benign alternative for microbially induced corrosion treatment is demonstrated. Bioengineered silver nanoparticles (AgNPs) surface functionalized with plant extract material (proteinacious) was generated in vitro in a test tube by treating ionic AgNO 3 with the leaf extract of Azadirachta indica that acted as dual reducing as well as stabilizing agent. Purity and crystallinity of the AgNPs, along with physical and surface characterizations, were evaluated by performing transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive x-ray spectra, single-area electron diffractions, zeta potential, and dynamic light scattering measurements. Anti-corrosion studies against mild steel (MS1010) by corrosion-inducive bacterium, Bacillus thuringiensis EN2 isolated from cooling towers, were evaluated by performing electrochemical impedance spectroscopy (EIS), weight loss analysis, and surface analysis by infrared spectroscopy. Our studies revealed that AgNPs profoundly inhibited the biofilm on MS1010 surface and reduced the corrosion rates with the CR of 0.5 mm/y and an inhibition efficiency of 77% when compared to plant extract alone with a CR of 2.2 mm/y and an inhibition efficiency of 52%. Further surface analysis by infrared spectra revealed that AgNPs formed a protective layer of self-assembled film on the surface of MS1010. Additionally, EIS and surface analysis revealed that the AgNPs have inhibited the bacterial biofilm and reduced the pit on MS1010. This is the first report disclosing the application of bioengineered AgNP formulations as potent anti-corrosive inhibitor upon forming a protective layer over mild steel in cooling water towers. Graphical Abstract ᅟ.

SpaceFibre: The Standard and the Multi-Lane Layer

NASA Astrophysics Data System (ADS)

Parkes, Steve; McClements, Chris; McLaren, David; Florit, Albert Ferrer; Gonzalez Villafranca, Alberto

2016-08-01

SpaceFibre is a new standard for spacecraft on-board data-handling networks, initially designed to deliver multi-Gbit/s data rates for synthetic aperture radar and high-resolution, multi-spectral imaging instruments, The addition of quality of service (QoS) and fault detection, isolation and recovery (FDIR) capabilities to SpaceFibre has resulted in a unified network technology. SpaceFibre provides high bandwidth, low latency, fault isolation and recovery suitable for space applications, and novel QoS that combines priority, bandwidth reservation and scheduling and which provides babbling node protection. SpaceFibre is backwards compatible with the widely used SpaceWire standard at the network level allowing simple interconnection of existing SpaceWire equipment to a SpaceFibre link or network.Developed by STAR-Dundee and the University of Dundee for the European Space Agency (ESA) SpaceFibre is able to operate over fibre-optic and electrical cable. A single lane of SpaceFibre comprises four signals (TX+/- and RX+/-) and supports data rates of 2 Gbits/s (2.5 Gbits/s data signalling rate) with data rates up to 5 Gbits/s already planned.Several lanes can operate together to provide a multi- lane link. Multi-laning increases the data-rate to well over 20 Gbits/s.This paper details the current state of SpaceFibre which is now in the process of formal standardisation by the European Cooperation for Space Standardization (ECSS). The multi-lane layer of SpaceFibre is then described.

VStar: Variable star data visualization and analysis tool

NASA Astrophysics Data System (ADS)

VStar Team

2014-07-01

VStar is a multi-platform, easy-to-use variable star data visualization and analysis tool. Data for a star can be read from the AAVSO (American Association of Variable Star Observers) database or from CSV and TSV files. VStar displays light curves and phase plots, can produce a mean curve, and analyzes time-frequency with Weighted Wavelet Z-Transform. It offers tools for period analysis, filtering, and other functions.

Detail-enhanced multimodality medical image fusion based on gradient minimization smoothing filter and shearing filter.

PubMed

Liu, Xingbin; Mei, Wenbo; Du, Huiqian

2018-02-13

In this paper, a detail-enhanced multimodality medical image fusion algorithm is proposed by using proposed multi-scale joint decomposition framework (MJDF) and shearing filter (SF). The MJDF constructed with gradient minimization smoothing filter (GMSF) and Gaussian low-pass filter (GLF) is used to decompose source images into low-pass layers, edge layers, and detail layers at multiple scales. In order to highlight the detail information in the fused image, the edge layer and the detail layer in each scale are weighted combined into a detail-enhanced layer. As directional filter is effective in capturing salient information, so SF is applied to the detail-enhanced layer to extract geometrical features and obtain directional coefficients. Visual saliency map-based fusion rule is designed for fusing low-pass layers, and the sum of standard deviation is used as activity level measurement for directional coefficients fusion. The final fusion result is obtained by synthesizing the fused low-pass layers and directional coefficients. Experimental results show that the proposed method with shift-invariance, directional selectivity, and detail-enhanced property is efficient in preserving and enhancing detail information of multimodality medical images. Graphical abstract The detailed implementation of the proposed medical image fusion algorithm.

Highly efficient blue and warm white organic light-emitting diodes with a simplified structure

NASA Astrophysics Data System (ADS)

Li, Xiang-Long; Ouyang, Xinhua; Chen, Dongcheng; Cai, Xinyi; Liu, Ming; Ge, Ziyi; Cao, Yong; Su, Shi-Jian

2016-03-01

Two blue fluorescent emitters were utilized to construct simplified organic light-emitting diodes (OLEDs) and the remarkable difference in device performance was carefully illustrated. A maximum current efficiency of 4.84 cd A-1 (corresponding to a quantum efficiency of 4.29%) with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.144, 0.127) was achieved by using N,N-diphenyl-4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1, 1‧:4‧, 1″-terphenyl]-4-amine (BBPI) as a non-doped emission layer of the simplified blue OLEDs without carrier-transport layers. In addition, simplified fluorescent/phosphorescent (F/P) hybrid warm white OLEDs without carrier-transport layers were fabricated by utilizing BBPI as (1) the blue emitter and (2) the host of a complementary yellow phosphorescent emitter (PO-01). A maximum current efficiency of 36.8 cd A-1 and a maximum power efficiency of 38.6 lm W-1 were achieved as a result of efficient energy transfer from the host to the guest and good triplet exciton confinement on the phosphorescent molecules. The blue and white OLEDs are among the most efficient simplified fluorescent blue and F/P hybrid white devices, and their performance is even comparable to that of most previously reported complicated multi-layer devices with carrier-transport layers.

Chip-scale white flip-chip light-emitting diode containing indium phosphide/zinc selenide quantum dots

NASA Astrophysics Data System (ADS)

Fan, Bingfeng; Yan, Linchao; Lao, Yuqin; Ma, Yanfei; Chen, Zimin; Ma, Xuejin; Zhuo, Yi; Pei, Yanli; Wang, Gang

2017-08-01

A method for preparing a quantum dot (QD)-white light-emitting diode (WLED) is reported. Holes were etched in the SiO2 layer deposited on the sapphire substrate of the flip-chip LED by inductively coupled plasma, and these holes were then filled with QDs. An ultraviolet-curable resin was then spin-coated on top of the QD-containing SiO2 layer, and the resin was cured to act as a protecting layer. The reflective sidewall structure minimized sidelight leakage. The fabrication of the QD-WLED is simple in preparation and compatible with traditional LED processes, which was the minimum size of the WLED chip-scale integrated package. InP/ZnS core-shell QDs were used as the converter in the WLED. A blue light-emitting diode with a flip-chip structure was used as the excitation source. The QD-WLED exhibited color temperatures from 5900 to 6400 K and Commission Internationale De L'Elcairage color coordinates from (0.315, 0.325) to (0.325, 0.317), under drive currents from 100 to 400 mA. The QD-WLED exhibited stable optoelectronic properties.

Proposal of AAA-battery-size one-shot ATR Fourier spectroscopic imager for on-site analysis: Simultaneous measurement of multi-components with high accuracy

NASA Astrophysics Data System (ADS)

Hosono, Satsuki; Qi, Wei; Sato, Shun; Suzuki, Yo; Fujiwara, Masaru; Hiramatsu, Hiroyuki; Suzuki, Satoru; Abeygunawardhana, P. K. W.; Wada, Kenji; Nishiyama, Akira; Ishimaru, Ichiro

2015-03-01

For simultaneous measurement of multi-components on-site like factories, the ultra-compact (diameter: 9[mm], length: 45[mm], weight: 200[g]) one-shot ATR (Attenuated Total Reflection) Fourier spectroscopic imager was proposed. Because the proposed one-shot Fourier spectroscopic imaging is based on spatial-phase-shift interferometer, interferograms could be obtained with simple optical configurations. We introduced the transmission-type relativeinclined phase-shifter, that was constructed with a cuboid prism and a wedge prism, onto the optical Fourier transform plane of infinity corrected optical systems. And also, small light-sources and cameras in the mid-infrared light region, whose size are several millimeter on a side, are essential components for the ultra-compact spectroscopic configuration. We selected the Graphite light source (light source area: 1.7×1.7[mm], maker: Hawkeye technologies) whose radiation factor was high. Fortunately, in these days we could apply the cost-effective 2-dimensional light receiving device for smartphone (e.g. product name: LEPTON, maker: FLIR, price: around 400USD). In the case of alcoholic drinks factory, conventionally workers measure glucose and ethanol concentrations by bringing liquid solution back to laboratories every day. The high portable spectroscopy will make it possible to measure multi-components simultaneously on manufacturing scene. But we found experimentally that absorption spectrum of glucose and water and ethanol were overlapped each other in near infrared light region. But for mid-infrared light region, we could distinguish specific absorption peaks of glucose (@10.5[μm]) and ethanol (@11.5[μm]) independently from water absorption. We obtained standard curve between absorption (@9.6[μm]) and ethanol concentration with high correlation coefficient 0.98 successfully by ATR imaging-type 2-dimensional Fourier spectroscopy (wavelength resolution: 0.057[μm]) with the graphite light source (maker: Hawkeye technologies, type: IR-75).

IntelliHealth: A medical decision support application using a novel weighted multi-layer classifier ensemble framework.

PubMed

Bashir, Saba; Qamar, Usman; Khan, Farhan Hassan

2016-02-01

Accuracy plays a vital role in the medical field as it concerns with the life of an individual. Extensive research has been conducted on disease classification and prediction using machine learning techniques. However, there is no agreement on which classifier produces the best results. A specific classifier may be better than others for a specific dataset, but another classifier could perform better for some other dataset. Ensemble of classifiers has been proved to be an effective way to improve classification accuracy. In this research we present an ensemble framework with multi-layer classification using enhanced bagging and optimized weighting. The proposed model called "HM-BagMoov" overcomes the limitations of conventional performance bottlenecks by utilizing an ensemble of seven heterogeneous classifiers. The framework is evaluated on five different heart disease datasets, four breast cancer datasets, two diabetes datasets, two liver disease datasets and one hepatitis dataset obtained from public repositories. The analysis of the results show that ensemble framework achieved the highest accuracy, sensitivity and F-Measure when compared with individual classifiers for all the diseases. In addition to this, the ensemble framework also achieved the highest accuracy when compared with the state of the art techniques. An application named "IntelliHealth" is also developed based on proposed model that may be used by hospitals/doctors for diagnostic advice. Copyright © 2015 Elsevier Inc. All rights reserved.

Multi-material size optimization of a ladder frame chassis

NASA Astrophysics Data System (ADS)

Baker, Michael

The Corporate Average Fuel Economy (CAFE) is an American fuel standard that sets regulations on fuel economy in vehicles. This law ultimately shapes the development and design research for automakers. Reducing the weight of conventional cars offers a way to improve fuel efficiency. This research investigated the optimality of an automobile's ladder frame chassis (LFC) by conducting multi-objective optimization on the LFC in order to reduce the weight of the chassis. The focus of the design and optimization was a ladder frame chassis commonly used for mass production light motor vehicles with an open-top rear cargo area. This thesis is comprised of two major sections. The first looked to perform thickness optimization in the outer walls of the ladder frame. In the second section, many multi-material distributions, including steel and aluminium varieties, were investigated. A simplified model was used to do an initial hand calculation analysis of the problem. This was used to create a baseline validation to compare the theory with the modeling. A CAD model of the LFC was designed. From the CAD model, a finite element model was extracted and joined using weld and bolt connectors. Following this, a linear static analysis was performed to look at displacement and stresses when subjected to loading conditions that simulate harsh driving conditions. The analysis showed significant values of stress and displacement on the ends of the rails, suggesting improvements could be made elsewhere. An optimization scheme was used to find the values of an all steel frame an optimal thickness distribution was found. This provided a 13% weight reduction over the initial model. To advance the analysis a multi-material approach was used to push the weight savings even further. Several material distributions were analyzed and the lightest utilized aluminium in all but the most strenuous subjected components. This enabled a reduction in weight of 15% over the initial model, equivalent to approximately 1 mile per gallon (MPG) in fuel economy.

Method for transmittance measurements in sunglasses for a kiosk

NASA Astrophysics Data System (ADS)

Mello, Marcio M.; Figueiredo, M.; Konda, R. A.; Ventura, Liliane

2013-03-01

Light transmittance measurements through sunglasses lenses is one of the required tests of the Brazilian Standard NBR15111(2004). Its measurement establishes the category of the sample and determines the required ultraviolet, visible and infrared protection, as well as the attenuation coefficient for signal light recognition. However, these measurements are usually performed by spectrophotometers and educated users, who are acknowledged to manage the equipment, use the weighting functions (WF) and interpret the data. We propose an alternative method, which consists in having matching optics and electronics to obtain a close WF to be used in transmittance measurements, and create an accessible device, for public self-use, providing a simple way for measuring and educating the public about sunglasses protection. Measurements were made in 30 samples for UV test, performed for the 280 - 400nm range, where UVA and UVB light sources and two photodiode sensors with Erythema action response are assembled, and for traffic signal a visible light sensor was used with spectral human eye response and different LEDs. As for the visible test, the visible light sensor was used for different light sources: incandescent, fluorescent, and a set of LEDs, while the infrared test is performed by several LEDs that provide the 780 - 2000nm range, and an infrared sensor. For these tests, only the samples spectrum were used. The transmittances were within the deviation limit required by NBR15111. The results have led us to build a self service kiosk for public use providing the category, UV protection and IR protection of the sunglasses as well as the information regarding its use for driving.

Strain dependence of In incorporation in m-oriented GaInN/GaN multi quantum well structures

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

Horenburg, Philipp, E-mail: p.horenburg@tu-braunschweig.de; Buß, Ernst Ronald; Rossow, Uwe

We demonstrate a strong dependence of the indium incorporation efficiency on the strain state in m-oriented GaInN/GaN multi quantum well (MQW) structures. Insertion of a partially relaxed AlInN buffer layer opens up the opportunity to manipulate the strain situation in the MQW grown on top. By lattice-matching this AlInN layer to the c- or a-axis of the underlying GaN, relaxation towards larger a- or smaller c-lattice constants can be induced, respectively. This results in a modified template for the subsequent MQW growth. From X-ray diffraction and photoluminescence measurements, we derive significant effects on the In incorporation efficiency and In concentrationsmore » in the quantum well (QW) up to x = 38% without additional accumulation of strain energy in the QW region. This makes strain manipulation a very promising method for growth of high In-containing MQW structures for efficient, long wavelength light-emitting devices.« less

Non-astigmatic imaging with matched pairs of spherically bent reflectors

DOEpatents

Bitter, Manfred Ludwig [Princeton, NJ; Hill, Kenneth Wayne [Plainsboro, NJ; Scott, Steven Douglas [Wellesley, MA; Feder, Russell [Newton, PA; Ko, Jinseok [Cambridge, MA; Rice, John E [N. Billerica, MA; Ince-Cushman, Alexander Charles [New York, NY; Jones, Frank [Manalapan, NJ

2012-07-10

Arrangements for the point-to-point imaging of a broad spectrum of electromagnetic radiation and ultrasound at large angles of incidence employ matched pairs of spherically bent reflectors to eliminate astigmatic imaging errors. Matched pairs of spherically bent crystals or spherically bent multi-layers are used for X-rays and EUV radiation; and matched pairs of spherically bent mirrors that are appropriate for the type of radiation are used with microwaves, infrared and visible light, or ultrasound. The arrangements encompass the two cases, where the Bragg angle--the complement to the angle of incidence in optics--is between 45.degree. and 90.degree. on both crystals/mirrors or between 0.degree. and 45.degree. on the first crystal/mirror and between 45.degree. and 90.degree. on the second crystal/mirror, where the angles of convergence and divergence are equal. For x-rays and EUV radiation, also the Bragg condition is satisfied on both spherically bent crystals/multi-layers.

GaAs shallow-homojunction solar cells

NASA Technical Reports Server (NTRS)

Fan, J. C. C.

1981-01-01

The feasibility of fabricating space resistant, high efficiency, light weight, low cost GaAs shallow homojunction solar cells for space application is investigated. The material preparation of ultrathin GaAs single crystal layers, and the fabrication of efficient GaAs solar cells on bulk GaAs substrates are discussed. Considerable progress was made in both areas, and conversion efficiency about 16% AMO was obtained using anodic oxide as a single layer antireflection coating. A computer design shows that even better cells can be obtained with double layer antireflection coating. Ultrathin, high efficiency solar cells were obtained from GaAs films prepared by the CLEFT process, with conversion efficiency as high as 17% at AMI from a 10 micrometers thick GaAs film. A organometallic CVD was designed and constructed.

Thermal performance of aircraft polyurethane seat cushions

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.

1982-01-01

Measurements were conducted on 7.6 x 7.6 cm samples of polyurethane seat cushion material in a modified National Bureau of Standards smoke density chamber to simulate real life conditions for an onboard aircraft fire or post-crash fire. In this study, a non-flaming heat radiation condition was simulated. Two aluminized polymeric fabrics (Norfab 11HT-26-A and Preox 1100-4) and one neoprene type material in two thicknesses (Vonar 2 and 3) were tested as heat blocking layers to protect the urethane foam from rapid heat degradation. Thermogravimetric analysis and differential scanning calorimetry were performed to characterize thermally the materials tested. It was found that Vonar 2 or 3 provided approximately equal thermal protection to F.R. urethane as the aluminized fabrics, but at a significant weight penalty. The efficiency of the foams to absorb heat per unit mass loss when protected with the heat blocking layer decreases in the heating range of 2.5-5.0 W/sq cm, but remains unchanged or slightly increases in the range of 5.0-7.5 W/sq cm. The results show that at all heat flux ranges tested the usage of a heat blocking layer in aircraft seats significantly improves their thermal performance.

Retinal axial focusing and multi-layer imaging with a liquid crystal adaptive optics camera

NASA Astrophysics Data System (ADS)

Liu, Rui-Xue; Zheng, Xian-Liang; Li, Da-Yu; Xia, Ming-Liang; Hu, Li-Fa; Cao, Zhao-Liang; Mu, Quan-Quan; Xuan, Li

2014-09-01

With the help of adaptive optics (AO) technology, cellular level imaging of living human retina can be achieved. Aiming to reduce distressing feelings and to avoid potential drug induced diseases, we attempted to image retina with dilated pupil and froze accommodation without drugs. An optimized liquid crystal adaptive optics camera was adopted for retinal imaging. A novel eye stared system was used for stimulating accommodation and fixating imaging area. Illumination sources and imaging camera kept linkage for focusing and imaging different layers. Four subjects with diverse degree of myopia were imaged. Based on the optical properties of the human eye, the eye stared system reduced the defocus to less than the typical ocular depth of focus. In this way, the illumination light can be projected on certain retina layer precisely. Since that the defocus had been compensated by the eye stared system, the adopted 512 × 512 liquid crystal spatial light modulator (LC-SLM) corrector provided the crucial spatial fidelity to fully compensate high-order aberrations. The Strehl ratio of a subject with -8 diopter myopia was improved to 0.78, which was nearly close to diffraction-limited imaging. By finely adjusting the axial displacement of illumination sources and imaging camera, cone photoreceptors, blood vessels and nerve fiber layer were clearly imaged successfully.

Study on the Impact Resistance of Bionic Layered Composite of TiC-TiB2/Al from Al-Ti-B4C System

PubMed Central

Zhao, Qian; Liang, Yunhong; Zhang, Zhihui; Li, Xiujuan; Ren, Luquan

2016-01-01

Mechanical property and impact resistance mechanism of bionic layered composite was investigated. Due to light weight and high strength property, white clam shell was chosen as bionic model for design of bionic layered composite. The intercoupling model between hard layer and soft layer was identical to the layered microstructure and hardness tendency of the white clam shell, which connected the bionic design and fabrication. TiC-TiB2 reinforced Al matrix composites fabricated from Al-Ti-B4C system with 40 wt. %, 50 wt. % and 30 wt. % Al contents were treated as an outer layer, middle layer and inner layer in hard layers. Pure Al matrix was regarded as a soft layer. Compared with traditional homogenous Al-Ti-B4C composite, bionic layered composite exhibited high mechanical properties including flexural strength, fracture toughness, compressive strength and impact toughness. The intercoupling effect of layered structure and combination model of hard and soft played a key role in high impact resistance of the bionic layered composite, proving the feasibility and practicability of the bionic model of a white clam shell. PMID:28773827

Digital imaging with solid state x-ray image intensifiers

NASA Astrophysics Data System (ADS)

Damento, Michael A.; Radspinner, Rachel; Roehrig, Hans

1999-10-01

X-ray cameras in which a CCD is lens coupled to a large phosphor screen are known to suffer from a loss of x-ray signal due to poor light collection from conventional phosphors, making them unsuitable for most medical imaging applications. By replacing the standard phosphor with a solid-state image intensifier, it may be possible to improve the signal-to-noise ratio of the images produced with these cameras. The solid-state x-ray image intensifier is a multi- layer device in which a photoconductor layer controls the light output from an electroluminescent phosphor layer. While prototype devices have been used for direct viewing and video imaging, they are only now being evaluated in a digital imaging system. In the present work, the preparation and evaluation of intensifiers with a 65 mm square format are described. The intensifiers are prepared by screen- printing or doctor blading the following layers onto an ITO coated glass substrate: ZnS phosphor, opaque layer, CdS photoconductor, and carbon conductor. The total thickness of the layers is approximately 350 micrometers , 350 VAC at 400 Hz is applied to the device for operation. For a given x-ray dose, the intensifiers produce up to three times the intensity (after background subtracting) of Lanex Fast Front screens. X-ray images produced with the present intensifiers are somewhat noisy and their resolution is about half that of Lanex screens. Modifications are suggested which could improve the resolution and noise of the intensifiers.

All-optical liquid crystal spatial light modulators

NASA Astrophysics Data System (ADS)

Tabiryan, Nelson; Grozhik, Vladimir; Khoo, Iam Choon; Nersisyan, Sarik R.; Serak, Svetlana

2003-12-01

Nonlinear optical processes in liquid crystals (LC) can be used for construction of all-optical spatial light modulators (SLM) where the photosensitivity and phase modulating functions are integrated into a single layer of an LC-material. Such spatial light integrated modulators (SLIMs) cost only a fraction of the conventional LC-SLM and can be used with high power laser radiation due to high transparency of LC materials and absence of light absorbing electrodes on the substrates of the LC-cell constituting the SLIM. Recent development of LC materials the photosensitivity of which is comparable to that of semiconductors has led to using SLIM in schemes of optical anti-jamming, sensor protection, and image processing. All-optical processes add remarkable versatility to the operation of SLIM harnessing the wealth inherent to light-matter interaction phenomena.

APPLICATION OF NEURAL NETWORK ALGORITHMS FOR BPM LINEARIZATION

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

Musson, John C.; Seaton, Chad; Spata, Mike F.

2012-11-01

Stripline BPM sensors contain inherent non-linearities, as a result of field distortions from the pickup elements. Many methods have been devised to facilitate corrections, often employing polynomial fitting. The cost of computation makes real-time correction difficult, particulalry when integer math is utilized. The application of neural-network technology, particularly the multi-layer perceptron algorithm, is proposed as an efficient alternative for electrode linearization. A process of supervised learning is initially used to determine the weighting coefficients, which are subsequently applied to the incoming electrode data. A non-linear layer, known as an activation layer, is responsible for the removal of saturation effects. Implementationmore » of a perceptron in an FPGA-based software-defined radio (SDR) is presented, along with performance comparisons. In addition, efficient calculation of the sigmoidal activation function via the CORDIC algorithm is presented.« less

A new UV-A/B protecting pigment in the terrestrial cyanobacterium Nostoc commune

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

Scherer, S.; Chen, T.W.; Boeger, P.

1988-12-01

A new ultraviolet (UV)-A/B absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium Nostoc commune is described. The pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar UV radiation but only in low concentrations in laboratory cultures illuminated by artificial light without UV. Its experimental induction by UV as well as its capacity to efficiently protect Nostoc against UV radiation is reported.

Effect of heat treatment on interfacial and mechanical properties of A6022/A7075/A6022 roll-bonded multi-layer Al alloy sheets

NASA Astrophysics Data System (ADS)

Cha, Joon-Hyeon; Kim, Su-Hyeon; Lee, Yun-Soo; Kim, Hyoung-Wook; Choi, Yoon Suk

2016-09-01

Multi-layered Al alloy sheets can exhibit unique properties by the combination of properties of component materials. A poor corrosion resistance of high strength Al alloys can be complemented by having a protective surface with corrosion resistant Al alloys. Here, a special care should be taken regarding the heat treatment of multi-layered Al alloy sheets because dissimilar Al alloys may exhibit unexpected interfacial reactions upon heat treatment. In the present study, A6022/A7075/A6022 sheets were fabricated by a cold roll-bonding process, and the effect of the heat treatment on the microstructure and mechanical properties was examined. The solution treatment gave rise to the diffusion of Zn, Mg, Cu and Si elements across the core/clad interface. In particular, the pronounced diffusion of Zn, which is a major alloying element (for solid-solution strengthening) of the A7075 core, resulted in a gradual hardness change across the core/clad interface. Mg2Si precipitates and the precipitate free zone were also formed near the interface after the heat treatment. The heat-treated sheet showed high strengths and reasonable elongation without apparent deformation misfit or interfacial delamination during the tensile deformation. The high strength of the sheet was mainly due to the T4 and T6 heat treatment of the A7075 core.

Transient analysis for alternating over-current characteristics of HTSC power transmission cable

NASA Astrophysics Data System (ADS)

Lim, S. H.; Hwang, S. D.

2006-10-01

In this paper, the transient analysis for the alternating over-current distribution in case that the over-current was applied for a high-TC superconducting (HTSC) power transmission cable was performed. The transient analysis for the alternating over-current characteristics of HTSC power transmission cable with multi-layer is required to estimate the redistribution of the over-current between its conducting layers and to protect the cable system from the over-current in case that the quench in one or two layers of the HTSC power cable happens. For its transient analysis, the resistance generation of the conducting layers for the alternating over-current was reflected on its equivalent circuit, based on the resistance equation obtained by applying discrete Fourier transform (DFT) for the voltage and the current waveforms of the HTSC tape, which comprises each layer of the HTSC power transmission cable. It was confirmed through the numerical analysis on its equivalent circuit that after the current redistribution from the outermost layer into the inner layers first happened, the fast current redistribution between the inner layers developed as the amplitude of the alternating over-current increased.

Novel hybrid light-emitting devices based on MAPbBr3 nanoplatelets:PVK nanocomposites and zinc oxide nanorod arrays

NASA Astrophysics Data System (ADS)

Wang, Szu-Ping; Chang, Chun-Kai; Yang, Sheng-Hsiung; Chang, Che-Yu; Chao, Yu-Chiang

2018-01-01

In this research, we demonstrate inverted perovskite light-emitting devices (PeLEDs) based on zinc oxide nanorod arrays (ZnO NAs) as the electron transport layer and methylammonium lead bromide nanoplatelets (MAPbBr3 NPLs) as the emissive material for the first time. The polyethyleneimine ethoxylated (PEIE) was inserted between the ZnO NAs and the MAPbBr3 NPLs layer to reduce the energy barrier and improve the electron injection efficiency. Besides, different weight ratios of poly(N-vinylcarbazole) (PVK) were blended with MAPbBr3 NPLs to make evenly dispersed nanocomposite films, thereby enhancing the performance of devices. Meanwhile, the photoluminescence of MAPbBr3 NPLs:PVK nanocomposite film was increased due to reduced self-quenching and prolonged carrier lifetime. Inverted PeLEDs with the configuration of ITO/PEIE-modified ZnO NAs/MAPbBr3 NPLs:PVK/TFB/Au were fabricated and evaluated, using TFB as the hole transport layer. The current density of the devices containing PVK matrix was significantly suppressed compared to those without PVK. Herein, the best device revealed a max brightness of 495 cd m-2 and a low turn-on voltage of 3.1 V that shows potential use in light-emitting applications.

NASA advanced aeronautics design solar powered remotely piloted vehicle

NASA Technical Reports Server (NTRS)

Elario, David S.; Guillmette, Neal H.; Lind, Gregory S.; Webster, Jonathan D.; Ferreira, Michael J.; Konstantakis, George C.; Marshall, David L.; Windt, Cari L.

1991-01-01

Environmental problems such as the depletion of the ozone layer and air pollution demand a change in traditional means of propulsion that is sensitive to the ecology. Solar powered propulsion is a favorable alternative that is both ecologically harmless as well as cost effective. Integration of solar energy into designs ranging from futuristic vehicles to heating is beneficial to society. The design and construction of a Multi-Purpose Remotely Piloted Vehicle (MPRPV) seeks to verify the feasibility of utilizing solar propulsion as a primary fuel source. This task has been a year long effort by a group of ten students, divided into five teams, each dealing with different aspects of the design. The aircraft was designed to take-off, climb to the design altitude, fly in a sustained figure-eight flight path, and cruise for approximately one hour. This mission requires flight at Reynolds numbers between 150,000 and 200,000 and demands special considerations in the aerodynamic design in order to achieve flight in this regime. Optimal performance requires a light weight configuration with both structural integrity and maximum power availability. The structure design and choice of solar cells for the propulsion was governed by the weight, efficiency, and cost considerations. The final design is a MPRPV weighting 35 N which cruises 7 m/s at the design altitude of 50 m. The configuration includes a wing composed of balsa and foam NACA 6409 airfoil sections and carbon fiber spars, a tail of similar construction, and a truss structure fuselage. The propulsion system consists of 98 10 percent efficient solar cells donated by Mobil Solar, a NiCad battery for energy storage, and a folding propeller regulated by a lightweight and efficient control system. The airfoils and propeller chosen for the design were research and tested during the design process.

Thermal, Radiation and Impact Protective Shields (TRIPS) for Robotic and Human Space Exploration Missions

NASA Technical Reports Server (NTRS)

Loomis, M. P.; Arnold, J. L.

2005-01-01

New concepts for protective shields for NASA s Crew Exploration Vehicles (CEVs) and planetary probes offer improved mission safety and affordability. Hazards include radiation from cosmic rays and solar particle events, hypervelocity impacts from orbital debris/ micrometeorites, and the extreme heating environment experienced during entry into planetary atmospheres. The traditional approach for the design of protection systems for these hazards has been to create single-function shields, i.e. ablative and blanket-based heat shields for thermal protection systems (TPS), polymer or other low-molecular-weight materials for radiation shields, and multilayer, Whipple-type shields for protection from hypervelocity impacts. This paper introduces an approach for the development of a single, multifunctional protective shield, employing nanotechnology- based materials, to serve simultaneously as a TPS, an impact shield and as the first line of defense against radiation. The approach is first to choose low molecular weight ablative TPS materials, (existing and planned for development) and add functionalized carbon nanotubes. Together they provide both thermal and radiation (TR) shielding. Next, impact protection (IP) is furnished through a tough skin, consisting of hard, ceramic outer layers (to fracture the impactor) and sublayers of tough, nanostructured fabrics to contain the debris cloud from the impactor before it can penetrate the spacecraft s interior.

Video Super-Resolution via Bidirectional Recurrent Convolutional Networks.

PubMed

Huang, Yan; Wang, Wei; Wang, Liang

2018-04-01

Super resolving a low-resolution video, namely video super-resolution (SR), is usually handled by either single-image SR or multi-frame SR. Single-Image SR deals with each video frame independently, and ignores intrinsic temporal dependency of video frames which actually plays a very important role in video SR. Multi-Frame SR generally extracts motion information, e.g., optical flow, to model the temporal dependency, but often shows high computational cost. Considering that recurrent neural networks (RNNs) can model long-term temporal dependency of video sequences well, we propose a fully convolutional RNN named bidirectional recurrent convolutional network for efficient multi-frame SR. Different from vanilla RNNs, 1) the commonly-used full feedforward and recurrent connections are replaced with weight-sharing convolutional connections. So they can greatly reduce the large number of network parameters and well model the temporal dependency in a finer level, i.e., patch-based rather than frame-based, and 2) connections from input layers at previous timesteps to the current hidden layer are added by 3D feedforward convolutions, which aim to capture discriminate spatio-temporal patterns for short-term fast-varying motions in local adjacent frames. Due to the cheap convolutional operations, our model has a low computational complexity and runs orders of magnitude faster than other multi-frame SR methods. With the powerful temporal dependency modeling, our model can super resolve videos with complex motions and achieve well performance.

Towards dropout training for convolutional neural networks.

PubMed

Wu, Haibing; Gu, Xiaodong

2015-11-01

Recently, dropout has seen increasing use in deep learning. For deep convolutional neural networks, dropout is known to work well in fully-connected layers. However, its effect in convolutional and pooling layers is still not clear. This paper demonstrates that max-pooling dropout is equivalent to randomly picking activation based on a multinomial distribution at training time. In light of this insight, we advocate employing our proposed probabilistic weighted pooling, instead of commonly used max-pooling, to act as model averaging at test time. Empirical evidence validates the superiority of probabilistic weighted pooling. We also empirically show that the effect of convolutional dropout is not trivial, despite the dramatically reduced possibility of over-fitting due to the convolutional architecture. Elaborately designing dropout training simultaneously in max-pooling and fully-connected layers, we achieve state-of-the-art performance on MNIST, and very competitive results on CIFAR-10 and CIFAR-100, relative to other approaches without data augmentation. Finally, we compare max-pooling dropout and stochastic pooling, both of which introduce stochasticity based on multinomial distributions at pooling stage. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multi-Layer Self-Nanoemulsifying Pellets: an Innovative Drug Delivery System for the Poorly Water-Soluble Drug Cinnarizine.

PubMed

Shahba, Ahmad Abdul-Wahhab; Ahmed, Abid Riaz; Alanazi, Fars Kaed; Mohsin, Kazi; Abdel-Rahman, Sayed Ibrahim

2018-04-25

Beside their solubility limitations, some poorly water-soluble drugs undergo extensive degradation in aqueous and/or lipid-based formulations. Multi-layer self-nanoemulsifying pellets (ML-SNEP) introduce an innovative delivery system based on isolating the drug from the self-nanoemulsifying layer to enhance drug aqueous solubility and minimize degradation. In the current study, various batches of cinnarizine (CN) ML-SNEP were prepared using fluid bed coating and involved a drug-free self-nanoemulsifying layer, protective layer, drug layer, moisture-sealing layer, and/or an anti-adherent layer. Each layer was optimized based on coating outcomes such as coating recovery and mono-pellets%. The optimized ML-SNEP were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), in vitro dissolution, and stability studies. The optimized ML-SNEP were free-flowing, well separated with high coating recovery. SEM showed multiple well-defined coating layers. The acidic polyvinylpyrrolidone:CN (4:1) solution presented excellent drug-layering outcomes. DSC and XRD confirmed CN transformation into amorphous state within the drug layer. The isolation between CN and self-nanoemulsifying layer did not adversely affect drug dissolution. CN was able to spontaneously migrate into the micelles arising from the drug-free self-nanoemulsifying layer. ML-SNEP showed superior dissolution compared to Stugeron® tablets at pH 1.2 and 6.8. Particularly, on shifting to pH 6.8, ML-SNEP maintained > 84% CN in solution while Stugeron® tablets showed significant CN precipitation leaving only 7% CN in solution. Furthermore, ML-SNEP (comprising Kollicoat® Smartseal 30D) showed robust stability and maintained > 97% intact CN within the accelerated storage conditions. Accordingly, ML-SNEP offer a novel delivery system that combines both enhanced solubilization and stabilization of unstable poorly soluble drugs.

Final Tests before MELIPAL "First Light"

NASA Astrophysics Data System (ADS)

2000-01-01

Secondary Mirror Now in Place Happy expectations are again growing at ESO's Paranal Observatory. For the third time in less than two years, the special moment of "First Light" for an 8.2-m VLT Unit Telescope is getting close - now is the turn of MELIPAL. Yesterday morning (January 20), the secondary mirror for MELIPAL was successfully coated with a thin layer of highly reflecting Aluminium. For this, the light-weight Beryllium mirror (about 50 kg) with a diameter of 1.1-m and covered with a layer of Nickel was carefully cleaned. It was subsequently placed in the large coating plant in which a target of exceedingly pure Aluminium is bombarded by fast argon ions. In this "sputtering" process, large numbers of Aluminium atoms are released from the target and deposited on the mirror. After about 15 minutes, the Aluminium layer had reached the desired thickness, 80 nm (= 0.00008 mm), or about 600 Aluminium atoms on top of each other. When the plant was opened, the reflectivity was measured as 91%, an excellent value. The equally successful coating of MELIPAL's main 8.2-m mirror was done in the same plant in late 1999, cf. ESO PR Photos 42a-ad/99. In the evening of January 20, the mirror was placed in its protective box and transported to the telescope enclosure. The mechanical structure of MELIPAL was tilted towards the horizon for easy access to the M2-Unit , the electro-mechanical support system for the secondary mirror at the top end. After removal of the M2 dummy mirror, the newly coated Beryllium mirror was cautiously mounted on its support. This delicate operation went smoothly, without any problems. With the optical mirrors in place, a further series of careful tests and thorough checks of all telescope functions will now follow. This will include extremely accurate balancing of the 450-tonnes telescope frame on its hydrostatic oil bearings, as well as precise adjustment of the various motions. Everything is controlled and monitored by computers and the ESO engineers will endeavour to tune the performance of the entire telescope to a high level of perfection, already at this stage. When the "First Light" observations are made some days from now, the light from the chosen celestial objects will be registered by the VLT Test Camera at the Cassegrain Focus. This comparatively simple instrument was also used for the "First Light" for ANTU and KUEYEN . It is mounted on the telescope's optical axis within the M1 Mirror Cell, just behind the main mirror. One or more of the astronomical images that will be obtained during MELIPAL "First Light" event will be made available on the web right after this important milestone of the VLT project. The following digital photos, most of which were obtained on January 20, illustrate the work on the M2 mirror described above.

Oxidation resistance, thermal conductivity, and spectral emittance of fully dense zirconium diboride with silicon carbide and tantalum diboride additives

NASA Astrophysics Data System (ADS)

Van Laningham, Gregg Thomas

Zirconium diboride (ZrB2) is a ceramic material possessing ultra-high melting temperatures. As such, this compound could be useful in the construction of thermal protection systems for aerospace applications. This work addresses a primary shortcoming of this material, namely its propensity to destructively oxidize at high temperatures, as well as secondary issues concerning its heat transport properties. To characterize and improve oxidation properties, thermogravimetric studies were performed using a specially constructed experimental setup. ZrB 2-SiC two-phase ceramic composites were isothermally oxidized for ~90 min in flowing air in the range 1500-1900°C. Specimens with 30 mol% SiC formed distinctive reaction product layers which were highly protective; 28 mol% SiC - 6 mol% TaB2 performed similarly. At higher temperatures, specimens containing lower amounts of SiC were shown to be non-protective, whereas specimens containing greater amounts of SiC produced unstable oxide layers due to gas evolution. Oxide coating thicknesses calculated from weight loss data were consistent with those measured from SEM micrographs. In order to characterize one aspect of the materials' heat transport properties, the thermal diffusivities of ZrB2-SiC composites were measured using the laser flash technique. These were converted to thermal conductivities using temperature dependent specific heat and density data; thermal conductivity decreased with increasing temperature over the range 25-2000°C. The composition with the highest SiC content showed the highest thermal conductivity at room temperature, but the lowest at temperatures in excess of ~400°C, because of the greater temperature sensitivity of the thermal conductivity of the SiC phase, as compared to more electrically-conductive ZrB2. Subsequent finite difference calculations were good predictors of multi-phase thermal conductvities for the compositions examined. The thermal conductivities of pure ZrB2 as a function of temperature were back-calculated from the experimental results for the multi-phase materials, and literature thermal conductivities of the other two phases. This established a relatively constant thermal conductivity of 88-104 W·K over the evaluated temperature range. Further heat transport characterization was performed using pre-oxidized, directly resistively heated ZrB2-30 mol% SiC ribbon specimens under the observation of a spectral radiometer. The ribbons were heated and held at specific temperatures over the range 1100-1330°C in flowing Ar, and normal spectral emittance values were recorded over the 1-6 μm range with a resolution of 10 nm. The normal spectral emittance was shown to decrease with loss of the borosilicate layer over the course of the data collection time periods. This change was measured and compensated for to produce traces showing the emittance of the oxidized composition rising from ~0.7 to ~0.9 over the range of wavelengths measured (1-6 μm).

Oceanic protection of prebiotic organic compounds from UV radiation

NASA Technical Reports Server (NTRS)

Cleaves, H. J.; Miller, S. L.; Bada, J. L. (Principal Investigator)

1998-01-01

It is frequently stated that UV light would cause massive destruction of prebiotic organic compounds because of the absence of an ozone layer. The elevated UV flux of the early sun compounds this problem. This applies to organic compounds of both terrestrial and extraterrestrial origin. Attempts to deal with this problem generally involve atmospheric absorbers. We show here that prebiotic organic polymers as well as several inorganic compounds are sufficient to protect oceanic organic molecules from UV degradation. This aqueous protection is in addition to any atmospheric UV absorbers and should be a ubiquitous planetary phenomenon serving to increase the size of planetary habitable zones.

Compact Efficient Lidar Receiver for Measuring Atmospheric Aerosols

NASA Technical Reports Server (NTRS)

Gili, Christopher; De Young, Russell

2006-01-01

A small, light weight, and efficient aerosol lidar receiver was constructed and tested. Weight and space savings were realized by using rigid optic tubes and mounting cubes to package the steering optics and detectors in a compact assembly. The receiver had a 1064nm channel using an APD detector. The 532nm channel was split (90/10) into an analog channel (90%) and a photon counting channel (10%). The efficiency of the 1064nm channel with optical filter was 44.0%. The efficiency of the analog 532nm channel was 61.4% with the optical filter, and the efficiency of the 532nm photon counting channel was 7.6% with the optical filter. The results of the atmospheric tests show that the detectors were able to consistently return accurate results. The lidar receiver was able to detect distinct cloud layers, and the lidar returns also agreed across the different detectors. The use of a light weight fiber-coupled telescope reduced weight and allowed great latitude in detector assembly positioning due to the flexibility enabled by the use of fiber optics. The receiver is now ready to be deployed for aircraft or ground based aerosol lidar measurements.

A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species.

PubMed

Onoda, Yusuke; Schieving, Feike; Anten, Niels P R

2015-05-01

Plant leaves commonly exhibit a thin, flat structure that facilitates a high light interception per unit mass, but may increase risks of mechanical failure when subjected to gravity, wind and herbivory as well as other stresses. Leaf laminas are composed of thin epidermis layers and thicker intervening mesophyll layers, which resemble a composite material, i.e. sandwich structure, used in engineering constructions (e.g. airplane wings) where high bending stiffness with minimum weight is important. Yet, to what extent leaf laminas are mechanically designed and behave as a sandwich structure remains unclear. To resolve this issue, we developed and applied a novel method to estimate stiffness of epidermis- and mesophyll layers without separating the layers. Across a phylogenetically diverse range of 36 angiosperm species, the estimated Young's moduli (a measure of stiffness) of mesophyll layers were much lower than those of the epidermis layers, indicating that leaf laminas behaved similarly to efficient sandwich structures. The stiffness of epidermis layers was higher in evergreen species than in deciduous species, and strongly associated with cuticle thickness. The ubiquitous nature of sandwich structures in leaves across studied species suggests that the sandwich structure has evolutionary advantages as it enables leaves to be simultaneously thin and flat, efficiently capturing light and maintaining mechanical stability under various stresses. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Flexible fabrication of multi-scale integrated 3D periodic nanostructures with phase mask

NASA Astrophysics Data System (ADS)

Yuan, Liang Leon

Top-down fabrication of artificial nanostructures, especially three-dimensional (3D) periodic nanostructures, that forms uniform and defect-free structures over large area with the advantages of high throughput and rapid processing and in a manner that can further monolithically integrate into multi-scale and multi-functional devices is long-desired but remains a considerable challenge. This thesis study advances diffractive optical element (DOE) based 3D laser holographic nanofabrication of 3D periodic nanostructures and develops new kinds of DOEs for advanced diffracted-beam control during the fabrication. Phase masks, as one particular kind of DOE, are a promising direction for simple and rapid fabrication of 3D periodic nanostructures by means of Fresnel diffraction interference lithography. When incident with a coherent beam of light, a suitable phase mask (e.g. with 2D nano-grating) can create multiple diffraction orders that are inherently phase-locked and overlap to form a 3D light interference pattern in the proximity of the DOE. This light pattern is typically recorded in photosensitive materials including photoresist to develop into 3D photonic crystal nanostructure templates. Two kinds of advanced phase masks were developed that enable delicate phase control of multiple diffraction beams. The first exploits femtosecond laser direct writing inside fused silica to assemble multiple (up to nine) orthogonally crossed (2D) grating layers, spaced on Talbot planes to overcome the inherent weak diffraction efficiency otherwise found in low-contrast volume gratings. A systematic offsetting of orthogonal grating layers to establish phase offsets over 0 to pi/2 range provided precise means for controlling the 3D photonic crystal structure symmetry between body centered tetragonal (BCT) and woodpile-like tetragonal (wTTR). The second phase mask consisted of two-layered nanogratings with small sub-wavelength grating periods and phase offset control. That was designed with isotropic properties attractive for generating a complete photonic band gap (PBG). An isolation layer was used between adjacent polymer layers to offer a reversal coating for sample preparation of scanning electron microscopy (SEM) imaging and top surface planarization. Electron beam lithography has been employed to fabricate a multi-level nano-grating phase mask that produces a diamond-like 3D nanostructure via phase mask lithography, promising for creating photonic crystal (PC) templates that can be inverted with high-index materials and form a complete PBG at telecommunication wavelengths. A laser scanning holographic method for 3D exposure in thick photoresist is introduced that combines the unique advantages of large area 3D holographic interference lithography (HIL) with the flexible patterning of laser direct writing to form both micro- and nano-structures in a single exposure step. Phase mask interference patterns accumulated over multiple overlapping scans are shown to stitch seamlessly and form highly uniform 3D nanostructure with beam size scaled to small 200 microm diameter. Further direct-write holography demonstrates monolithical writing of multi-scale lab-on-a-chip with multiple functionalities including on-chip integrated fluorescence. Various 3D periodic nanostructures are demonstrated over a 15 mmx15 mm area, through full 40 microm photoresist thickness and with uniform structural and optical properties revealed by focused ion beam (FIB) milling, SEM imaging and stopband measures. The lateral and axial periods scale from respective 1500 nm to 570 nm and 9.2 microm to 1.2 microm to offer a Gamma-Z stopband at 1.5 microm. Overall, laser scanning is presented as a facile means to embed 3D PC nanostructure within microfluidic channels for integration into an optofluidic lab-on-chip, demonstrating a new laser HIL writing approach for creating multi-scale integrated microsystems.

Wireless optical network for a home network

NASA Astrophysics Data System (ADS)

Bouchet, Olivier; Porcon, Pascal; Walewski, Joachim W.; Nerreter, Stefan; Langer, Klaus-Dieter; Fernández, Luz; Vucic, Jelena; Kamalakis, Thomas; Ntogari, Georgia; Neokosmidis, Ioannis; Gueutier, Eric

2010-08-01

During the European collaborative project OMEGA, two optical-wireless prototypes have been developed. The first prototype operates in the near-infrared spectral region and features Giga Ethernet connectivity, a simple transceiver architecture due to the use of on-off keying, a multi-sector transceiver, and an ultra-fast switch for sector-to-sector hand over. This full-duplex system, composed by one base station and one module, transmits data on three meters. The second prototype is a visible-light-communications system based on DMT signal processing and an adapted MAC sublayer. Data rates around to 100 Mb/s at the physical layer are achieved. This broadcast system, composed also by one base station and one module, transmits data up to two meters. In this paper we present the adapted optical wireless media-access-control sublayer protocol for visible-light communications. This protocol accommodates link adaptation from 128 Mb/s to 1024 Mb/s with multi-sector coverage, and half-duplex or full-duplex transmission.

Optimization of the laser remelting process for HVOF-sprayed Stellite 6 wear resistant coatings

NASA Astrophysics Data System (ADS)

Ciubotariu, Costel-Relu; Frunzăverde, Doina; Mărginean, Gabriela; Șerban, Viorel-Aurel; Bîrdeanu, Aurel-Valentin

2016-03-01

Cobalt base alloys are used in all industrial areas due to their excellent wear resistance. Several studies have shown that Stellite 6 coatings are suitable not only for protection against sliding wear, but also in case of exposure to impact loading. In this respect, a possible application is the protection of hydropower plant components affected by cavitation. The main problem in connection with Stellite 6 is the deposition procedure of the protective layers, both welding and thermal spraying techniques requesting special measures in order to prevent the brittleness of the coating. In this study, Stellite 6 layers were HVOF thermally sprayed on a martensitic 13-4 stainless steel substrate, as usually used for hydraulic machinery components. In order to improve the microstructure of the HVOF-sprayed coatings and their adhesion to the substrate, laser remelting was applied, using a TRUMPF Laser type HL 124P LCU and different working parameters. The microstructure of the coatings, obtained for various remelting conditions, was evaluated by light microscopy, showing the optimal value of the pulse power, which provided a homogenous Stellite 6 layer with good adhesion to the substrate.

Development of a test device to characterize thermal protective performance of fabrics against hot steam and thermal radiation

NASA Astrophysics Data System (ADS)

Su, Yun; Li, Jun

2016-12-01

Steam burns severely threaten the life of firefighters in the course of their fire-ground activities. The aim of this paper was to characterize thermal protective performance of flame-retardant fabrics exposed to hot steam and low-level thermal radiation. An improved testing apparatus based on ASTM F2731-11 was developed in order to simulate the routine fire-ground conditions by controlling steam pressure, flow rate and temperature of steam box. The thermal protective performance of single-layer and multi-layer fabric system with/without an air gap was studied based on the calibrated tester. It was indicated that the new testing apparatus effectively evaluated thermal properties of fabric in hot steam and thermal radiation. Hot steam significantly exacerbated the skin burn injuries while the condensed water on the skin’s surface contributed to cool down the skin tissues during the cooling. Also, the absorbed thermal energy during the exposure and the cooling was mainly determined by the fabric’s configuration, the air gap size, the exposure time and the existence of hot steam. The research provides a effective method to characterize the thermal protection of fabric in complex conditions, which will help in optimization of thermal protection performance of clothing and reduction of steam burn.

Triple-Layer Plastic Bags Protect Dry Common Beans (Phaseolus vulgaris) Against Damage by Acanthoscelides obtectus (Coleoptera: Chrysomelidae) During Storage.

PubMed

Mutungi, C; Affognon, H D; Njoroge, A W; Manono, J; Baributsa, D; Murdock, L L

2015-10-01

Fumigated dry common beans (Phaseolus vulgaris L.) that were artificially infested with Acanthoscelides obtectus Say, and others that were not artificially infested, were stored in hermetic triple-layer PICS (Lela Agro, Kano, Nigeria) or woven polypropylene (PP) bags for 6 mo at ambient laboratory temperature conditions of 22.6 ± 1.9°C and 60.1 ± 4.3% relative humidity. In an additional trial, beans contained in PP bags were treated with Actellic Super dust before introducing A. obtectus. Moisture content, number of live adult A. obtectus, seed damage, weight loss, and seed germination were determined at monthly intervals. At 6 mo, beans stored in PICS bags retained higher moisture than those stored in PP bags, but in all treatments the moisture level remained below that recommended for safe storage of beans. In the PICS bags, proliferation of A. obtectus did not proceed and at 6 mo, beans stored in these bags did not have insect-inflicted seed damage or weight loss. In contrast, seed damage and weight loss in PP bags exceeded economic threshold after 1 mo in the absence of Actellic Super dust (Syngenta Crop protection AG, Basle, Switzerland), and after 2 mo in the presence of it. Germination of beans stored in PP bags decreased greatly whereas the beans stored in PICS bags did not show reduced germination. Chemical free storage of common beans in PICS bags protects them against damage by A. obtectus. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Multi-layer seal for electrochemical devices

DOEpatents

Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

2010-11-16

Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

Multi-layer seal for electrochemical devices

DOEpatents

Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

2010-09-14

Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

Tough Textiles Protect Payloads and Public Safety Officers

NASA Technical Reports Server (NTRS)

2009-01-01

In order to create the Mars Pathfinder s mission-critical airbags in the 1990s, NASA s Jet Propulsion Laboratory collaborated with New Ipswich, New Hampshire s Warwick Mills Inc. to weave multi-layer textiles for the airbags for both Pathfinder and the Mars Exploration Rovers. Warwick Mills applied techniques from the collaboration to its puncture- and impact-resistant TurtleSkin product line. The company's metal flex armor (MFA) vests offer stab protection comparable with rigid steel plates and over 50,000 of the vests have sold. The SoftPlate body armor offers protection from handgun bullets, and like the MFA, is designed to be more comfortable than rigid vests. International public safety and military customers are now benefiting from the TurtleSkin products.

Groundwater assessment in Salboni Block, West Bengal (India) using remote sensing, geographical information system and multi-criteria decision analysis techniques

NASA Astrophysics Data System (ADS)

Jha, Madan K.; Chowdary, V. M.; Chowdhury, Alivia

2010-11-01

An approach is presented for the evaluation of groundwater potential using remote sensing, geographic information system, geoelectrical, and multi-criteria decision analysis techniques. The approach divides the available hydrologic and hydrogeologic data into two groups, exogenous (hydrologic) and endogenous (subsurface). A case study in Salboni Block, West Bengal (India), uses six thematic layers of exogenous parameters and four thematic layers of endogenous parameters. These thematic layers and their features were assigned suitable weights which were normalized by analytic hierarchy process and eigenvector techniques. The layers were then integrated using ArcGIS software to generate two groundwater potential maps. The hydrologic parameters-based groundwater potential zone map indicated that the `good' groundwater potential zone covers 27.14% of the area, the `moderate' zone 45.33%, and the `poor' zone 27.53%. A comparison of this map with the groundwater potential map based on subsurface parameters revealed that the hydrologic parameters-based map accurately delineates groundwater potential zones in about 59% of the area, and hence it is dependable to a certain extent. More than 80% of the study area has moderate-to-poor groundwater potential, which necessitates efficient groundwater management for long-term water security. Overall, the integrated technique is useful for the assessment of groundwater resources at a basin or sub-basin scale.

Coherent backscattering effect in spectra of icy satellites and its modeling using multi-sphere T-matrix (MSTM) code for layers of particles

NASA Astrophysics Data System (ADS)

Pitman, Karly M.; Kolokolova, Ludmilla; Verbiscer, Anne J.; Mackowski, Daniel W.; Joseph, Emily C. S.

2017-12-01

The coherent backscattering effect (CBE), the constructive interference of light scattering in particulate surfaces (e.g., regolith), manifests as a non-linear increase in reflectance, or opposition surge, and a narrow negative polarization feature at small solar phase angles. Due to a strong dependence of the amplitude and angular width of this opposition surge on the absorptive characteristics of the surface material, CBE also produces phase-angle-dependent variations in the near-infrared spectra. In this paper we present a survey of such variations in the spectra of icy satellites of Saturn obtained by the Cassini spacecraft's Visual and Infrared Mapping Spectrometer (VIMS) and in the ground-based spectra of Oberon, a satellite of Uranus, obtained with TripleSpec, a cross-dispersed near-infrared spectrometer on the Astrophysical Research Consortium 3.5-m telescope located at the Apache Point Observatory near Sunspot, New Mexico. The paper also presents computer modeling of the saturnian satellite spectra and their phase-angle variations using the most recent version of the Multi-Sphere T-Matrix (MSTM) code developed to simulate light scattering by layers of randomly distributed spherical particles. The modeling allowed us not only to reproduce the observed effects but also to estimate characteristics of the icy particles that cover the surfaces of Rhea, Dione, and Tethys.

Micro-precision control/structure interaction technology for large optical space systems

NASA Technical Reports Server (NTRS)

Sirlin, Samuel W.; Laskin, Robert A.

1993-01-01

The CSI program at JPL is chartered to develop the structures and control technology needed for sub-micron level stabilization of future optical space systems. The extreme dimensional stability required for such systems derives from the need to maintain the alignment and figure of critical optical elements to a small fraction (typically 1/20th to 1/50th) of the wavelength of detected radiation. The wavelength is about 0.5 micron for visible light and 0.1 micron for ultra-violet light. This lambda/50 requirement is common to a broad class of optical systems including filled aperture telescopes (with monolithic or segmented primary mirrors), sparse aperture telescopes, and optical interferometers. The challenge for CSI arises when such systems become large, with spatially distributed optical elements mounted on a lightweight, flexible structure. In order to better understand the requirements for micro-precision CSI technology, a representative future optical system was identified and developed as an analytical testbed for CSI concepts and approaches. An optical interferometer was selected as a stressing example of the relevant mission class. The system that emerged was termed the Focus Mission Interferometer (FMI). This paper will describe the multi-layer control architecture used to address the FMI's nanometer level stabilization requirements. In addition the paper will discuss on-going and planned experimental work aimed at demonstrating that multi-layer CSI can work in practice in the relevant performance regime.

p-Type Transparent Conducting Oxide/n-Type Semiconductor Heterojunctions for Efficient and Stable Solar Water Oxidation.

PubMed

Chen, Le; Yang, Jinhui; Klaus, Shannon; Lee, Lyman J; Woods-Robinson, Rachel; Ma, Jie; Lum, Yanwei; Cooper, Jason K; Toma, Francesca M; Wang, Lin-Wang; Sharp, Ian D; Bell, Alexis T; Ager, Joel W

2015-08-05

Achieving stable operation of photoanodes used as components of solar water splitting devices is critical to realizing the promise of this renewable energy technology. It is shown that p-type transparent conducting oxides (p-TCOs) can function both as a selective hole contact and corrosion protection layer for photoanodes used in light-driven water oxidation. Using NiCo2O4 as the p-TCO and n-type Si as a prototypical light absorber, a rectifying heterojunction capable of light driven water oxidation was created. By placing the charge separating junction in the Si using a np(+) structure and by incorporating a highly active heterogeneous Ni-Fe oxygen evolution catalyst, efficient light-driven water oxidation can be achieved. In this structure, oxygen evolution under AM1.5G illumination occurs at 0.95 V vs RHE, and the current density at the reversible potential for water oxidation (1.23 V vs RHE) is >25 mA cm(-2). Stable operation was confirmed by observing a constant current density over 72 h and by sensitive measurements of corrosion products in the electrolyte. In situ Raman spectroscopy was employed to investigate structural transformation of NiCo2O4 during electrochemical oxidation. The interface between the light absorber and p-TCO is crucial to produce selective hole conduction to the surface under illumination. For example, annealing to produce more crystalline NiCo2O4 produces only small changes in its hole conductivity, while a thicker SiOx layer is formed at the n-Si/p-NiCo2O4 interface, greatly reducing the PEC performance. The generality of the p-TCO protection approach is demonstrated by multihour, stable, water oxidation with n-InP/p-NiCo2O4 heterojunction photoanodes.