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Sample records for silicon sensitive region

  1. Integrated X-ray and charged particle active pixel CMOS sensor arrays using an epitaxial silicon sensitive region

    SciTech Connect

    Kleinfelder, Stuart; Bichsel, Hans; Bieser, Fred; Matis, Howard S.; Rai, Gulshan; Retiere, Fabrice; Weiman, Howard; Yamamoto, Eugene

    2002-07-01

    Integrated CMOS Active Pixel Sensor (APS) arrays have been fabricated and tested using X-ray and electron sources. The 128 by 128 pixel arrays, designed in a standard 0.25 micron process, use a {approx}10 micron epitaxial silicon layer as a deep detection region. The epitaxial layer has a much greater thickness than the surface features used by standard CMOS APS, leading to stronger signals and potentially better signal-to-noise ratio (SNR). On the other hand, minority carriers confined within the epitaxial region may diffuse to neighboring pixels, blur images and reduce peak signal intensity. But for low-rate, sparse-event images, centroid analysis of this diffusion may be used to increase position resolution. Careful trade-offs involving pixel size and sense-node area verses capacitance must be made to optimize overall performance. The prototype sensor arrays, therefore, include a range of different pixel designs, including different APS circuits and a range of different epitaxial layer contact structures. The fabricated arrays were tested with 1.5 GeV electrons and Fe-55 X-ray sources, yielding a measured noise of 13 electrons RMS and an SNR for single Fe-55 X-rays of greater than 38.

  2. Bond Sensitivity to Silicone Contamination

    NASA Technical Reports Server (NTRS)

    Caldwell, G. A.; Hudson, W. D.; Hudson, W. D.; Cash, Stephen F. (Technical Monitor)

    2003-01-01

    Currently during fabrication of the Space Shuttle booster rocket motors, the use of silicone and silicone-containing products is prohibited in most applications. Many shop aids and other materials containing silicone have the potential, if they make contact with a bond surface, to transfer some of the silicone to the substrates being bonded. Such transfer could result in a reduction of the bond strength or even failure of the subsequent bonds. This concern is driving the need to understand the effect of silicones and the concentration needed to affect a given bond-line strength. Additionally, as silicone detection methods used for materials acceptance improve what may have gone unnoticed earlier is now being detected. Thus, realistic silicone limits for process materials (below which bond performance is satisfactory) are needed rather than having an absolute no silicone permitted policy.

  3. New pressure-sensitive silicone adhesive

    NASA Technical Reports Server (NTRS)

    Leiffer, J. L.; Stoops, W. E., Jr.; St. Clair, T. L.; Watkins, V. E., Jr.; Kelly, T. P.

    1981-01-01

    Adhesive for high or low temperatures does not stretch severely under load. It is produced by combining intermediate-molecular-weight pressure sensitive adhesive which does not cure with silicone resin that cures with catalyst to rubbery tack-free state. Blend of silicone tackifier and cured rubbery silicone requires no solvents in either atmospheric or vacuum environments. Ratio of ingredients varies for different degrees of tack, creep resistance, and tensile strength.

  4. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1998-06-02

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  5. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1996-01-01

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  6. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1998-06-02

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  7. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1996-01-30

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  8. Directionally Sensitive Silicon Radiation Sensor (VCELL)

    NASA Technical Reports Server (NTRS)

    Cook, Koy B.

    2002-01-01

    Sensors are a mission critical element in many NASA programs and require some very unique properties such as small size, low power, high reliability, low weight. Low cost sensors offer the possibility of technology transfer to the public domain for commercial applications. One sensor application that is important to many NASA programs is the ability to point at a radiation source, such as the sun. Such sensors may be an integral part of the guidance and control systems in space platforms and in remote exploratory vehicles. Sun/solar pointing is also important for ground-based systems such as solar arrays. These systems are not required to be small and lightweight. However, if a sensor with a sun pointing capability was developed that is very small, rugged, lightweight and at the same time low cost, it certainly could be used in existing and perhaps many new ground based applications, The objective of the VCELL (Directionally Sensitive Silicon Radiation Sensor) research is to develop a new and very unique silicon based directionally sensitive radiation sensor which can be fabricated using conventional monolithic IC technologies and which will meet the above requirements. The proposed sensor is a novel silicon chip that is directionally sensitive to incident radiation, providing azimuth and elevation information on the incident radiation. The resulting sensor chip will be appropriate for integration into a silicon IC or useful in a hybrid structure to be interfaced with a standard IEEE 1451 bus interface IC to create an Intelligent Sensor. It is presently estimated that it will require about three man-years of effort to complete the VCELL research and development. This includes the optical, electrical, mechanical and silicon fabrication and testing as well as computer simulations and theoretical analysis and modeling including testing in simulated space environments, This report summarizes the sensor research completed this summer as part of the Summer Faculty

  9. Polycrystalline silicon ion sensitive field effect transistors

    NASA Astrophysics Data System (ADS)

    Yan, F.; Estrela, P.; Mo, Y.; Migliorato, P.; Maeda, H.; Inoue, S.; Shimoda, T.

    2005-01-01

    We report the operation of polycrystalline silicon ion sensitive field effect transistors. These devices can be fabricated on inexpensive disposable substrates such as glass or plastics and are, therefore, promising candidates for low cost single-use intelligent multisensors. In this work we have developed an extended gate structure with a Si3N4 sensing layer. Nearly ideal pH sensitivity (54mV /pH) and stable operation have been achieved. Temperature effects have been characterized. A penicillin sensor has been fabricated by functionalizing the sensing area with penicillinase. The sensitivity to penicillin G is about 10mV/mM, in solutions with concentration lower than the saturation value, which is about 7 mM.

  10. Shear sensitive silicon piezoresistive tactile sensor prototype

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Beebe, David J.

    1998-09-01

    Shear sensing ability it important in many fields such as robotics, rehabilitation, teleoperation and human computer interfaces. A shear sensitive tactile sensor prototype is developed based on the principles of the piezoresistive effect in silicon, and using microfabrication technology. Analogous to the conventional silicon piezoresistive pressure sensor, piezoresistive resistors embedded in a silicon diaphragm are used to sense stress change. An additional mesa is fabricated on the top of the diaphragm and serves to transform an applied force to a stress. Both the shear and normal components of the force are resolved by measuring the resistance changes of the four resistors placed at the corners of a prism mesa. The prototype is tested both statically and dynamically when a spatial force of 0 - 300 gram is applied. Good linearity (R > 0.98) and high repeatability are observed. In this paper, the force sensing mechanism and force determination approach are described. The fabrication process is presented. The preliminary testing results are presented and discussed.

  11. Making Porous Luminescent Regions In Silicon Wafers

    NASA Technical Reports Server (NTRS)

    Fathauer, Robert W.; Jones, Eric W.

    1994-01-01

    Regions damaged by ion implantation stain-etched. Porous regions within single-crystal silicon wafers fabricated by straightforward stain-etching process. Regions exhibit visible photoluminescence at room temperature and might constitute basis of novel class of optoelectronic devices. Stain-etching process has advantages over recently investigated anodic-etching process. Process works on both n-doped and p-doped silicon wafers. Related development reported in article, "Porous Si(x)Ge(1-x) Layers Within Single Crystals of Si," (NPO-18836).

  12. Highly sensitive silicon microreactor for catalyst testing

    SciTech Connect

    Henriksen, Toke R.; Hansen, Ole; Olsen, Jakob L.; Vesborg, Peter; Chorkendorff, Ib

    2009-12-15

    A novel microfabricated chemical reactor for highly sensitive measurements of catalytic activity and surface kinetics is presented. The reactor is fabricated in a silicon chip and is intended for gas-phase reactions at pressures ranging from 0.1 to 5.0 bar. A high sensitivity is obtained by directing the entire gas flow through the catalyst bed to a mass spectrometer, thus ensuring that nearly all reaction products are present in the analyzed gas flow. Although the device can be employed for testing a wide range of catalysts, the primary aim of the design is to allow characterization of model catalysts which can only be obtained in small quantities. Such measurements are of significant fundamental interest but are challenging because of the low surface areas involved. The relationship between the reaction zone gas flow and the pressure in the reaction zone is investigated experimentally. A corresponding theoretical model is presented, and the gas flow through an on-chip flow-limiting capillary is predicted to be in the intermediate regime. The experimental data for the gas flow are found to be in good agreement with the theoretical model. At typical experimental conditions, the total gas flow through the reaction zone is around 3x10{sup 14} molecules s{sup -1}, corresponding to a gas residence time in the reaction zone of about 11 s. To demonstrate the operation of the microreactor, CO oxidation on low-area platinum thin film circles is employed as a test reaction. Using temperature ramping, it is found that platinum catalysts with areas as small as 15 {mu}m{sup 2} are conveniently characterized with the device.

  13. High sensitivity silicon single nanowire junctionless phototransistor

    NASA Astrophysics Data System (ADS)

    Das, Samaresh; Dhyani, Veerendra; Georgiev, Yordan M.; Williams, David A.

    2016-02-01

    A high-gain photodetector based on junctionless MOSEFT has been presented in this work. Tri-gate junctionless nanowire phototransistors were fabricated on (100) silicon-on-insulator wafers with a buried oxide of thickness 145 nm and top silicon layer of thickness 10 nm. The gate stack consisted of a 10 nm SiO2 dielectric and a 50 nm poly-Si gate electrode. The channel length and doping concentration of junctionless n-MOSFETs was 1 μm and 3 × 1019 cm-3, respectively. The dark current of this device measured at room temperature was less than 1 pA. The measured internal gain of the device was about 35 for 860 nm light illumination. The photocurrent was 300 times larger than the dark current for only 30 nW incident power on the nanowire at 300 mV drain bias.

  14. Porous silicon ring resonator for compact, high sensitivity biosensing applications

    SciTech Connect

    Rodriguez, Gilberto A.; Hu, Shuren; Weiss, Sharon M.

    2015-01-01

    A ring resonator is patterned on a porous silicon slab waveguide to produce a compact, high quality factor biosensor with a large internal surface area available for enhanced recognition of biological and chemical molecules. The porous nature of the ring resonator allows molecules to directly interact with the guided mode. Quality factors near 10,000 were measured for porous silicon ring resonators with a radius of 25 μm. A bulk detection sensitivity of 380 nm/RIU was measured upon exposure to salt water solutions. Specific detection of nucleic acid molecules was demonstrated with a surface detection sensitivity of 4 pm/nM.

  15. Improving sensitivity of piezoresistive microcantilever biosensors using stress concentration region designs

    NASA Astrophysics Data System (ADS)

    Ansari, M. Z.; Cho, C.; Choi, W.; Lee, M.; Lee, S.; Kim, J.

    2013-12-01

    To improve the surface-stress sensitivity of piezoresistive microcantilever biosensors, this study presents cantilever designs with circular, square and triangular stress concentration regions (SCRs). The cantilever substrates are made of silicon and silicon dioxide and the piezoresistor is p-doped silicon. The cantilevers are characterized using FEM software for their surface-stress sensitivity and thermal vulnerability by applying surface stress, temperature and bias voltage loads. A relation for the surface-stress sensitivity of a silicon cantilever is also presented. Results show that use of SCRs in a silicon cantilever can improve its sensitivity by up to 55% and that a square SCR is the most suitable design to improve the overall sensitivity.

  16. Large Silicon Abundance in Photodissociation Regions

    NASA Astrophysics Data System (ADS)

    Okada, Yoko; Onaka, Takashi; Nakagawa, Takao; Shibai, Hiroshi; Tomono, Daigo; Yui, Yukari Y.

    2006-03-01

    We have made one-dimensional raster scan observations of the ρ Oph and σ Sco star-forming regions with two spectrometers (SWS and LWS) on board the ISO. In the ρ Oph region, [Si II] 35 μm, [O I] 63 μm, 146 μm, [C II] 158 μm, and the H2 pure rotational transition lines S(0) to S(3) are detected, and the photodissociation region (PDR) properties are derived as the radiation field scaled by the solar neighborhood value G0~30-500, the gas density n~250-2500 cm-3, and the surface temperature T~100-400 K. The ratio of [Si II] 35 μm to [O I] 146 μm indicates that silicon of 10%-20% of the solar abundance must be in the gaseous form in the PDR, suggesting that efficient dust destruction is ongoing even in the PDR and that a fraction of the silicon atoms may be contained in volatile forms in dust grains. The [O I] 63 μm and [C II] 158 μm emissions are too weak relative to [O I] 146 μm to be accounted for by standard PDR models. We propose a simple model, in which overlapping PDR clouds along the line of sight absorb the [O I] 63 μm and [C II] 158 μm emissions, and show that the proposed model reproduces the observed line intensities fairly well. In the σ Sco region, we have detected three fine-structure lines, [O I] 63 μm, [N II] 122 μm, and [C II] 158 μm, and derived that 30%-80% of the [C II] emission comes from the ionized gas. The upper limit of the [Si II] 35 μm is compatible with the solar abundance relative to nitrogen, and no useful constraint on the gaseous Si is obtained for the σ Sco region. Based on observations with ISO, an ESA project with instruments funded by ESA member states (especially the PI countries: France, Germany, the Netherlands, and the UK) and with the participation of ISAS and NASA.

  17. Integrated cooling channels in position-sensitive silicon detectors

    NASA Astrophysics Data System (ADS)

    Andricek, L.; Boronat, M.; Fuster, J.; Garcia, I.; Gomis, P.; Marinas, C.; Ninkovic, J.; Perelló, M.; Villarejo, M. A.; Vos, M.

    2016-06-01

    We present an approach to construct position-sensitive silicon detectors with an integrated cooling circuit. Tests on samples demonstrate that a very modest liquid flow very effectively cool the devices up to a power dissipation of over 10 W/cm2. The liquid flow is found to have a negligible impact on the mechanical stability. A finite-element simulation predicts the cooling performance to an accuracy of approximately 10%.

  18. Gold nanoparticles embedded silicon channel biosensor for improved sensitivity

    NASA Astrophysics Data System (ADS)

    Chang, H. Y.; Arshad, M. K. Md.; M. Nuzaihan M., N.; Fathil, M. F. M.; Hashim, U.

    2016-07-01

    This project discusses the fabrication steps of a biosensor device on silicon-on-insulator (SOI) wafer. Conventional photolithography technique is used to fabricate the device. The gold nanoparticles (GNPs) are then used to enhance the sensitivity of the device. By incorporating the GNPs, it is expected to get higher current compared with the device without GNPs due to better conductivity of gold and higher volume-to-ratio. Hence, with the addition of GNPs, it may boost up the signal and enhance the sensitivity of the device.

  19. Ultraviolet /UV/ sensitive phosphors for silicon imaging detectors

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Cowens, M. W.; Butner, C. L.

    1981-01-01

    The fluorescence properties of UV sensitive organic phosphors and the radiometric properties of phosphor coated silicon detectors in the VUV, UV, and visible wavelengths are described. With evaporated films of coronene and liumogen, effective quantum efficiencies of up to 20% have been achieved on silicon photodiodes in the vacuum UV. With thin films of methylmethacrylate (acrylic), which are doped with organic laser dyes and deposited from solution, detector quantum efficiencies of the order of 15% for wavelengths of 120-165 nm and of 40% for wavelengths above 190 nm have been obtained. The phosphor coatings also act as antireflection coatings and thereby enhance the response of coated devices throughout the visible and near IR.

  20. Non-contact monitoring of electrical characteristics of silicon surface and near-surface region

    NASA Astrophysics Data System (ADS)

    Roman, P.; Brubaker, M.; Staffa, J.; Kamieniecki, E.; Ruzyllo, J.

    1998-11-01

    The SPV-based method of Surface Charge Profiling (SCP) is discussed, and its applications in silicon surface monitoring in IC manufacturing are reviewed. The SCP method shows high sensitivity to changes in the condition of the Si surface (e.g. surface cleaning operations) and a very thin near-surface region (e.g. variations of active dopant concentration near the surface).

  1. Ion implantation reduces radiation sensitivity of metal oxide silicon /MOS/ devices

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Implanting nitrogen ions improves hardening of silicon oxides 30 percent to 60 percent against ionizing radiation effects. Process reduces sensitivity, but retains stability normally shown by interfaces between silicon and thermally grown oxides.

  2. RF performances of inductors integrated on localized p+-type porous silicon regions

    NASA Astrophysics Data System (ADS)

    Capelle, Marie; Billoué, Jérôme; Poveda, Patrick; Gautier, Gaël

    2012-09-01

    To study the influence of localized porous silicon regions on radiofrequency performances of passive devices, inductors were integrated on localized porous silicon regions, full porous silicon sheet, bulk silicon and glass substrates. In this work, a novel strong, resistant fluoropolymer mask is introduced to localize the porous silicon on the silicon wafer. Then, the quality factors and resonant frequencies obtained with the different substrates are presented. A first comparison is done between the performances of inductors integrated on same-thickness localized and full porous silicon sheet layers. The effect of the silicon regions in the decrease of performances of localized porous silicon is discussed. Then, the study shows that the localized porous silicon substrate significantly reduces losses in comparison with high-resistivity silicon or highly doped silicon bulks. These results are promising for the integration of both passive and active devices on the same silicon/porous silicon hybrid substrate.

  3. A porous silicon optical microcavity for sensitive bacteria detection

    NASA Astrophysics Data System (ADS)

    Li, Sha; Huang, Jianfeng; Cai, Lintao

    2011-10-01

    A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (~10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml - 1 at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml - 1. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

  4. Position Sensitive Detectors Mounted with Scintillators and Silicon Photomultipliers

    NASA Astrophysics Data System (ADS)

    Carvalhaes, Roberto P. M.; Bonifácio, Daniel A. B.; Moralles, Maurício

    2011-08-01

    This work presents the first results obtained in the "Assembly and characterization of position sensitive detectors composed of scintillators coupled to silicon photomultipliers" project. The development of new x and γ radiation detectors have found several technological applications, especially in medical physics, where γ detectors that can be used in high intensity magnetic field are of particular importance. The experimental setup consisted of coupling of two silicon photomultipliers (SiPM) to the small sides of a 3×3×100 mm3 scintillator and the coupling of one SiPM to one of the small sides of a 3×3×10 mm3 scintillator. We found that the detectors used in this study presented an energy resolution that is in agreement with those observed in scintillators of the same family coupled to conventional photomultipliers. Besides that, there is a strong correlation between the difference of the light intensity in both SiPMs of the long detector and the position of the γ source. The results confirm the great potential of application of such detectors.

  5. High efficiency neutron sensitive amorphous silicon pixel detectors

    SciTech Connect

    Mireshghi, A.; Cho, G.; Drewery, J.S.; Hong, W.S.; Jing, T.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V.

    1993-11-01

    A multi-layer a-Si:H based thermal neutron detector was designed, fabricated and simulated by Monte Carlo method. The detector consists of two PECVD deposited a-Si:H pin detectors interfaced with coated layers of Gd, as a thermal neutron converter. Simulation results indicate that a detector consisting of 2 Gd films with thicknesses of 2 and 4 {mu}m, sandwiched properly with two layers of sufficiently thick ({approximately}30{mu}m) amorphous silicon diodes, has the optimum parameters. The detectors have an intrinsic efficiency of about 42% at a threshold setting of 7000 electrons, with an expected average signal size of {approximately}12000 electrons which is well above the noise. This efficiency will be further increased to nearly 63%, if we use Gd with 50% enrichment in {sup 157}Gd. We can fabricate position sensitive detectors with spatial resolution of 300 {mu}m with gamma sensitivity of {approximately}1 {times} 10{sup {minus}5}. These detectors are highly radiation resistant and are good candidates for use in various application, where high efficiency, high resolution, gamma insensitive position sensitive neutron detectors are needed.

  6. Low-resistivity photon-transparent window attached to photo-sensitive silicon detector

    DOEpatents

    Holland, Stephen Edward

    2000-02-15

    The invention comprises a combination of a low resistivity, or electrically conducting, silicon layer that is transparent to long or short wavelength photons and is attached to the backside of a photon-sensitive layer of silicon, such as a silicon wafer or chip. The window is applied to photon sensitive silicon devices such as photodiodes, charge-coupled devices, active pixel sensors, low-energy x-ray sensors and other radiation detectors. The silicon window is applied to the back side of a photosensitive silicon wafer or chip so that photons can illuminate the device from the backside without interference from the circuit printed on the frontside. A voltage sufficient to fully deplete the high-resistivity photosensitive silicon volume of charge carriers is applied between the low-resistivity back window and the front, patterned, side of the device. This allows photon-induced charge created at the backside to reach the front side of the device and to be processed by any circuitry attached to the front side. Using the inventive combination, the photon sensitive silicon layer does not need to be thinned beyond standard fabrication methods in order to achieve full charge-depletion in the silicon volume. In one embodiment, the inventive backside window is applied to high resistivity silicon to allow backside illumination while maintaining charge isolation in CCD pixels.

  7. Near-ultraviolet-sensitive graphene/porous silicon photodetectors.

    PubMed

    Kim, Jungkil; Joo, Soong Sin; Lee, Kyeong Won; Kim, Ju Hwan; Shin, Dong Hee; Kim, Sung; Choi, Suk-Ho

    2014-12-10

    Porous silicon (PSi) is recognized as an attractive building block for photonic devices because of its novel properties including high ratio of surface to volume and high light absorption. We first report near-ultraviolet (UV)-sensitive graphene/PSi photodetectors (PDs) fabricated by utilizing graphene and PSi as a carrier collector and a photoexcitation layer, respectively. Thanks to high light absorption and enlarged energy-band gap of PSi, the responsivity (Ri) and quantum efficiency (QE) of the PDs are markedly enhanced in the near-UV range. The performances of PDs are systemically studied for various porosities of PSi, controlled by varying the electroless-deposition time (td) of Ag nanoparticles for the use of Si etching. Largest gain is obtained at td = 3 s, consistent with the maximal enhancement of Ri and QE in the near UV range, which originates from the well-defined interface at the graphene/PSi junction, as proved by atomic- and electrostatic-force microscopies. Optimized response speed is ∼10 times faster compared to graphene/single-crystalline Si PDs. These and other unique PD characteristics prove to be governed by typical Schottky diode-like transport of charge carriers at the graphene/PSi junctions, based on bias-dependent variations of the band profiles, resulting in novel dark- and photocurrent behaviors. PMID:25384018

  8. High-Sensitivity Temperature-Independent Silicon Photonic Microfluidic Biosensors

    NASA Astrophysics Data System (ADS)

    Kim, Kangbaek

    Optical biosensors that can precisely quantify the presence of specific molecular species in real time without the need for labeling have seen increased use in the drug discovery industry and molecular biology in general. Of the many possible optical biosensors, the TM mode Si biosensor is shown to be very attractive in the sensing application because of large field amplitude on the surface and cost effective CMOS VLSI fabrication. Noise is the most fundamental factor that limits the performance of sensors in development of high-sensitivity biosensors, and noise reduction techniques require precise studies and analysis. One such example stems from thermal fluctuations. Generally SOI biosensors are vulnerable to ambient temperature fluctuations because of large thermo-optic coefficient of silicon (˜2x10 -4 RIU/K), typically requiring another reference ring and readout sequence to compensate temperature induced noise. To address this problem, we designed sensors with a novel TM-mode shallow-ridge waveguide that provides both large surface amplitude for bulk and surface sensing. With proper design, this also provides large optical confinement in the aqueous cladding that renders the device athermal using the negative thermo-optic coefficient of water (~ --1x10-4RIU/K), demonstrating cancellation of thermo-optic effects for aqueous solution operation near 300K. Additional limitations resulting from mechanical actuator fluctuations, stability of tunable lasers, and large 1/f noise of lasers and sensor electronics can limit biosensor performance. Here we also present a simple harmonic feedback readout technique that obviates the need for spectrometers and tunable lasers. This feedback technique reduces the impact of 1/f noise to enable high-sensitivity, and a DSP lock-in with 256 kHz sampling rate can provide down to micros time scale monitoring for fast transitions in biomolecular concentration with potential for small volume and low cost. In this dissertation, a novel

  9. Highly sensitive and reproducible silicon-based surface-enhanced Raman scattering sensors for real applications.

    PubMed

    Wang, Houyu; Jiang, Xiangxu; He, Yao

    2016-08-15

    During the past few decades, thanks to silicon nanomaterials' outstanding electronic/optical/mechanical properties, large surface-to-volume ratio, abundant surface chemistry, facile tailorability and good compatibility with modern semiconductor industry, different dimensional silicon nanostructures have been widely employed for rationally designing and fabricating high-performance surface-enhanced Raman scattering (SERS) sensors for the detection of various chemical and biological species. Among these, two-dimensional silicon nanostructures made of metal nanoparticle-modified silicon wafers and three-dimensional silicon nanostructures made of metal nanoparticle-decorated SiNW arrays are of particular interest, and have been extensively exploited as promising silicon-based SERS-active substrates for the construction of high-performance SERS sensors. With an aim to retrospect these important and exciting achievements, we herein focus on reviewing recent representative studies on silicon-based SERS sensors for sensing applications from a broad perspective and possible future direction, promoting readers' awareness of these novel powerful silicon-based SERS sensing technologies. Firstly, we summarize the two unique merits of silicon-based SERS sensors, and those are high sensitivity and good reproducibility. Next, we present recent advances of two- and three-dimensional silicon-based SERS sensors, especially for real applications. Finally, we discuss the major challenges and prospects for the development of silicon-based SERS sensors. PMID:27414500

  10. Spectral sensitivity of graphene/silicon heterojunction photodetectors

    NASA Astrophysics Data System (ADS)

    Riazimehr, Sarah; Bablich, Andreas; Schneider, Daniel; Kataria, Satender; Passi, Vikram; Yim, Chanyoung; Duesberg, Georg S.; Lemme, Max C.

    2016-01-01

    We have studied the optical properties of two-dimensional (2D) Schottky photodiode heterojunctions made of chemical vapor deposited (CVD) graphene on n- and p-type silicon (Si) substrates. Much better rectification behavior is observed from the diodes fabricated on n-Si substrates in comparison with the devices on p-Si substrates in dark condition. Also, graphene - n-Si photodiodes show a considerable responsivity of 270 mA W-1 within the silicon spectral range in DC reverse bias condition. The present results are furthermore compared with that of a molybdenum disulfide (MoS2) - p-type silicon photodiode.

  11. Method of making selective crystalline silicon regions containing entrapped hydrogen by laser treatment

    DOEpatents

    Pankove, Jacques I.; Wu, Chung P.

    1982-01-01

    A novel hydrogen rich single crystalline silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystalline silicon without out-gasing the hydrogen. The new material can be used to fabricate semi-conductor devices such as single crystalline silicon solar cells with surface window regions having a greater band gap energy than that of single crystalline silicon without hydrogen.

  12. Illumination-invariant face recognition with a contrast sensitive silicon retina

    SciTech Connect

    Buhmann, J.M.; Lades, M.; Eeckman, F.

    1993-11-29

    Changes in lighting conditions strongly effect the performance and reliability of computer vision systems. We report face recognition results under drastically changing lighting conditions for a computer vision system which concurrently uses a contrast sensitive silicon retina and a conventional, gain controlled CCD camera. For both input devices the face recognition system employs an elastic matching algorithm with wavelet based features to classify unknown faces. To assess the effect of analog on-chip preprocessing by the silicon retina the CCD images have been digitally preprocessed with a bandpass filter to adjust the power spectrum. The silicon retina with its ability to adjust sensitivity increases the recognition rate up to 50 percent. These comparative experiments demonstrate that preprocessing with an analog VLSI silicon retina generates image data enriched with object-constant features.

  13. Polarization sensitive anisotropic structuring of silicon by ultrashort light pulses

    SciTech Connect

    Zhang, Jingyu; Drevinskas, Rokas Beresna, Martynas; Kazansky, Peter G.

    2015-07-27

    Imprinting of anisotropic structures on the silicon surface by double pulse femtosecond laser irradiation is demonstrated. The origin of the polarization-induced anisotropy is explained in terms of interaction of linearly polarized second pulse with the wavelength-sized symmetric crater-shaped structure generated by the linearly polarized first pulse. A wavefront sensor is fabricated by imprinting an array of micro-craters. Polarization controlled anisotropy of the structures can be also explored for data storage applications.

  14. Puzzles in Silicon NMR: Sensitivity to Experimental Parameters

    NASA Astrophysics Data System (ADS)

    Li, Dale; Dementyev, Anatoly; Maclean, Kenneth; Dong, Yanqun; Ramos, Rona; Barrett, Sean

    2004-03-01

    Recent observations of anomalously long-lived spin echoes in Silicon are still not understood [A.E. Dementyev, D. Li, K. MacLean, S.E. Barrett, Phys. Rev. B 68, 153302 (2003).]. Echo trains exist well beyond the calculated dipolar dephasing time and exhibit unusual even-odd echo asymmetry. This talk will discuss the effects and implications of changing many experimental parameters including magnetic field strength, temperature, pulse width, pulse angle, and repetition rate. Understanding what limits coherent evolution in clean dipolar solids is relevant for all physical qubits.

  15. Porous silicon nanoparticles as sensitizers for ultrasonic hyperthermia

    SciTech Connect

    Sviridov, A. P. Andreev, V. G.; Ivanova, E. M.; Osminkina, L. A.; Tamarov, K. P.; Timoshenko, V. Yu.

    2013-11-04

    Aqueous suspensions of porous silicon nanoparticles (NPs) with average size ∼100 nm and concentration ∼1 g/L undergo significant heating as compared with pure water under therapeutic ultrasonic (US) irradiation with frequencies of 1–2.5 MHz and intensities of 1–20 W/cm{sup 2}. This effect is explained by taking into account the efficient absorption of US energy by NPs. The observed US-induced heating of biodegradable NPs is promising for applications in ultrasonic hyperthermia of tumors.

  16. Slow light engineering for high Q high sensitivity photonic crystal microcavity biosensors in silicon

    PubMed Central

    Chakravarty, Swapnajit; Zou, Yi; Lai, Wei-Cheng; Chen, Ray T.

    2012-01-01

    Current trends in photonic crystal microcavity biosensors in silicon-on-insulator (SOI), that focus on small and smaller sensors have faced a bottleneck trying to balance two contradictory requirements of resonance quality factor and sensitivity. By simultaneous control of the radiation loss and optical mode volumes, we show that both requirements can be satisfied simultaneously. Microcavity sensors are designed in which resonances show highest Q ~9,300 in the bio-ambient phosphate buffered saline (PBS) as well as highest sensitivity among photonic crystal biosensors. We experimentally demonstrated mass sensitivity 8.8 atto-grams with sensitivity per unit area of 0.8 picograms/mm2 Highest sensitivity, irrespective of the dissociation constant Kd, is demonstrated among all existing label-free optical biosensors in silicon at the concentration of 0.1μg/ml. PMID:22748964

  17. Vertically etched silicon nano-rods as a sensitive electron detector

    NASA Astrophysics Data System (ADS)

    Hajmirzaheydarali, M.; Akbari, M.; Soleimani-Amiri, S.; Sadeghipari, M.; Shahsafi, A.; Farahani, A. Akhavan; Mohajerzadeh, S.

    2015-07-01

    We have used vertically etched silicon nano-rods to realize electron detectors suitable for scanning electron microscopes. The results of deep etching of silicon nano-structures are presented to achieve highly ordered arrays of nano-rods. The response of the electron detector to energy of the primary electron beam and the effects of various sizes and materials has been investigated, indicating its high sensitivity to secondary and back-scattered electrons. The miniaturized structure of this electron detector allows it to be placed in the vicinity of the specimen to improve the resolution and contrast. This detector collects electrons and converts the electron current to voltage directly by means of n-doped silicon nano-rods on a p-type silicon substrate. Silicon nano-rods enhance the surface-to-volume ratio of the detector as well as improving the yield of electron detection. The use of nano-structures and silicon nanowires as an electron detector has led to higher sensitivities than with micro-structures.

  18. Sensitivity Enhancement of Transition Metal Dichalcogenides/Silicon Nanostructure-based Surface Plasmon Resonance Biosensor

    NASA Astrophysics Data System (ADS)

    Ouyang, Qingling; Zeng, Shuwen; Jiang, Li; Hong, Liying; Xu, Gaixia; Dinh, Xuan-Quyen; Qian, Jun; He, Sailing; Qu, Junle; Coquet, Philippe; Yong, Ken-Tye

    2016-06-01

    In this work, we designed a sensitivity-enhanced surface plasmon resonance biosensor structure based on silicon nanosheet and two-dimensional transition metal dichalcogenides. This configuration contains six components: SF10 triangular prism, gold thin film, silicon nanosheet, two-dimensional MoS2/MoSe2/WS2/WSe2 (defined as MX2) layers, biomolecular analyte layer and sensing medium. The minimum reflectivity, sensitivity as well as the Full Width at Half Maximum of SPR curve are systematically examined by using Fresnel equations and the transfer matrix method in the visible and near infrared wavelength range (600 nm to 1024 nm). The variation of the minimum reflectivity and the change in resonance angle as the function of the number of MX2 layers are presented respectively. The results show that silicon nanosheet and MX2 layers can be served as effective light absorption medium. Under resonance conditions, the electrons in these additional dielectric layers can be transferred to the surface of gold thin film. All silicon-MX2 enhanced sensing models show much better performance than that of the conventional sensing scheme where pure Au thin film is used, the highest sensitivity can be achieved by employing 600 nm excitation light wavelength with 35 nm gold thin film and 7 nm thickness silicon nanosheet coated with monolayer WS2.

  19. Sensitivity Enhancement of Transition Metal Dichalcogenides/Silicon Nanostructure-based Surface Plasmon Resonance Biosensor

    PubMed Central

    Ouyang, Qingling; Zeng, Shuwen; Jiang, Li; Hong, Liying; Xu, Gaixia; Dinh, Xuan-Quyen; Qian, Jun; He, Sailing; Qu, Junle; Coquet, Philippe; Yong, Ken-Tye

    2016-01-01

    In this work, we designed a sensitivity-enhanced surface plasmon resonance biosensor structure based on silicon nanosheet and two-dimensional transition metal dichalcogenides. This configuration contains six components: SF10 triangular prism, gold thin film, silicon nanosheet, two-dimensional MoS2/MoSe2/WS2/WSe2 (defined as MX2) layers, biomolecular analyte layer and sensing medium. The minimum reflectivity, sensitivity as well as the Full Width at Half Maximum of SPR curve are systematically examined by using Fresnel equations and the transfer matrix method in the visible and near infrared wavelength range (600 nm to 1024 nm). The variation of the minimum reflectivity and the change in resonance angle as the function of the number of MX2 layers are presented respectively. The results show that silicon nanosheet and MX2 layers can be served as effective light absorption medium. Under resonance conditions, the electrons in these additional dielectric layers can be transferred to the surface of gold thin film. All silicon-MX2 enhanced sensing models show much better performance than that of the conventional sensing scheme where pure Au thin film is used, the highest sensitivity can be achieved by employing 600 nm excitation light wavelength with 35 nm gold thin film and 7 nm thickness silicon nanosheet coated with monolayer WS2. PMID:27305974

  20. Sensitivity Enhancement of Transition Metal Dichalcogenides/Silicon Nanostructure-based Surface Plasmon Resonance Biosensor.

    PubMed

    Ouyang, Qingling; Zeng, Shuwen; Jiang, Li; Hong, Liying; Xu, Gaixia; Dinh, Xuan-Quyen; Qian, Jun; He, Sailing; Qu, Junle; Coquet, Philippe; Yong, Ken-Tye

    2016-01-01

    In this work, we designed a sensitivity-enhanced surface plasmon resonance biosensor structure based on silicon nanosheet and two-dimensional transition metal dichalcogenides. This configuration contains six components: SF10 triangular prism, gold thin film, silicon nanosheet, two-dimensional MoS2/MoSe2/WS2/WSe2 (defined as MX2) layers, biomolecular analyte layer and sensing medium. The minimum reflectivity, sensitivity as well as the Full Width at Half Maximum of SPR curve are systematically examined by using Fresnel equations and the transfer matrix method in the visible and near infrared wavelength range (600 nm to 1024 nm). The variation of the minimum reflectivity and the change in resonance angle as the function of the number of MX2 layers are presented respectively. The results show that silicon nanosheet and MX2 layers can be served as effective light absorption medium. Under resonance conditions, the electrons in these additional dielectric layers can be transferred to the surface of gold thin film. All silicon-MX2 enhanced sensing models show much better performance than that of the conventional sensing scheme where pure Au thin film is used, the highest sensitivity can be achieved by employing 600 nm excitation light wavelength with 35 nm gold thin film and 7 nm thickness silicon nanosheet coated with monolayer WS2. PMID:27305974

  1. Silicon nanowires for high-sensitivity glucose detection

    NASA Astrophysics Data System (ADS)

    Chen, Weiwei; Yao, Hui; Tzang, Chi Hung; Zhu, Junjie; Yang, Mengsu; Lee, Shuit-Tong

    2006-05-01

    Silicon nanowires (SiNWs) were investigated as supporting matrices for enzyme immobilization to construct glucose biosensors. Glucose oxidase was adsorbed onto SiNWs after different treatments, either as grown, HF etched, or carboxylic acid (COOH) functionalized. The amperometric biosensor with COOH-functionalized SiNWs performed the best with a detection limit of 0.01mM glucose (signal-to-noise ratio=3). For real-time detection of glucose, SiNW biosensor showed a linear response in the range of 0.1-15mM. This work demonstrates the utility of SiNWs as a biosensor component and provides a general method to modify the surface of semiconducting nanomaterials for potential biomedical applications.

  2. SENSITIVITY OF ZOOPLANKTON INDICATORS IN REGIONAL MONITORING

    EPA Science Inventory

    This study describes an approach for assessing and selecting ecological indicators for regional monitoring of northeastern US lakes. We analyze the components of variance for indicators of zooplankton richness and abundance in the context of the spatial and temporal sampling des...

  3. Turbulence sensitivity study in the IBI region

    NASA Astrophysics Data System (ADS)

    Reffray, G.; Chanut, J.; Cailleau, S.; Levier, B.

    2009-04-01

    In the framework of building a high resolution operational system covering the IBI area (Iberian Biscay Irish), a turbulence sensitivity study is carried out to improve the results of the NEMO model. This is particularly important on the shelf where the mixing is very strong and mainly induced by the intense tidal currents. The investigated work is to test some parameterizations more sophisticated (for ex: stability functions from Canuto (2001) or surface boundary conditions including wave effects from Mellor and Blumberg 2003) and to note if the biases with the observations are reduced as expected. To make this numerical study easier, the Generic Length Scale model (Umlauf and Burchard, 2003) has been implemented. The choice of the dissipation rate as turbulent scale has been done because this closure is well documented and contrary to the Mellor-Yamada turbulent scale, this equation does not need any wall function to provide results physically relevant.

  4. Estimation of regional differences in wind erosion sensitivity in Hungary

    NASA Astrophysics Data System (ADS)

    Mezõsi, G.; Blanka, V.; Bata, T.; Kovács, F.; Meyer, B.

    2013-09-01

    In Hungary, wind erosion is one of the most serious natural hazards. Spatial and temporal variation in the factors that determine the location and intensity of wind erosion damage are not well known, nor are the regional and local sensitivities to erosion. Because of methodological challenges, no multi-factor, regional wind erosion sensitivity map is available for Hungary. The aim of this study was to develop a method to estimate the regional differences in wind erosion sensitivity and exposure in Hungary. Wind erosion sensitivity was modelled using the key factors of soil sensitivity, vegetation cover and wind erodibility as proxies. These factors were first estimated separately by factor sensitivity maps and later combined by fuzzy logic into a regional-scale wind erosion sensitivity map. Large areas were evaluated by using publicly available datasets of remotely sensed vegetation information, soil maps and meteorological data on wind speed. The resulting estimates were verified by field studies and examining the economic losses from wind erosion as compensated by the state insurance company. The spatial resolution of the resulting sensitivity map is suitable for regional applications, as identifying sensitive areas is the foundation for diverse land development control measures and implementing management activities.

  5. Estimation of regional differences in wind erosion sensitivity in Hungary

    NASA Astrophysics Data System (ADS)

    Mezősi, G.; Blanka, V.; Bata, T.; Kovács, F.; Meyer, B.

    2015-01-01

    In Hungary, wind erosion is one of the most serious natural hazards. Spatial and temporal variation in the factors that determine the location and intensity of wind erosion damage are not well known, nor are the regional and local sensitivities to erosion. Because of methodological challenges, no multi-factor, regional wind erosion sensitivity map is available for Hungary. The aim of this study was to develop a method to estimate the regional differences in wind erosion sensitivity and exposure in Hungary. Wind erosion sensitivity was modelled using the key factors of soil sensitivity, vegetation cover and wind erodibility as proxies. These factors were first estimated separately by factor sensitivity maps and later combined by fuzzy logic into a regional-scale wind erosion sensitivity map. Large areas were evaluated by using publicly available data sets of remotely sensed vegetation information, soil maps and meteorological data on wind speed. The resulting estimates were verified by field studies and examining the economic losses from wind erosion as compensated by the state insurance company. The spatial resolution of the resulting sensitivity map is suitable for regional applications, as identifying sensitive areas is the foundation for diverse land development control measures and implementing management activities.

  6. Method of making selective crystalline silicon regions containing entrapped hydrogen by laser treatment

    DOEpatents

    Pankove, J.I.; Wu, C.P.

    1982-03-30

    A novel hydrogen rich single crystalline silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystalline silicon without out-gassing the hydrogen. The new material can be used to fabricate semi-conductor devices such as single crystalline silicon solar cells with surface window regions having a greater band gap energy than that of single crystalline silicon without hydrogen. 2 figs.

  7. Characterization of multilayer reflectors and position sensitive detectors in the 45--300 A region

    SciTech Connect

    Yamashita, K.; Takahashi, S. ); Kitamoto, S.; Takahama, S.; Tamura, K. ); Hatsukade, I. ); Sakurai, M. ); Watanabe, M. ); Yamaguchi, A. ); Nagata, H.; Ohtani, M. )

    1992-01-01

    Multilayer reflectors and position sensitive detectors have been developed in constructing imaging optical systems in the 45--300 A region. Molybdenum-silicon (2{ital d}=140 A, {ital N}=20) and nickel--carbon (2{ital d}=100 A, {ital N}=20) multilayers were deposited on a spherical mirror (25 cm in diameter) for the normal incidence and on a segment of paraboloidal mirror (20 cm{times}10 cm) for 30{degree} grazing incidence. Their optical characteristics were evaluated by using characteristic x rays and monochromatized synchrotron radiation in the 45--300 A region. A position sensitive detector is made of a tandem microchannel plate (MCP) with a CsI photocathode and resistive plate, which is placed at the focal plane of each mirror. The detection efficiency and position resolution were measured by using characteristic x rays of C{ital K}{alpha} and monochromatized synchrotron radiation in the 45--200 A region.

  8. Schottky barrier amorphous silicon solar cell with thin doped region adjacent metal Schottky barrier

    DOEpatents

    Carlson, David E.; Wronski, Christopher R.

    1979-01-01

    A Schottky barrier amorphous silicon solar cell incorporating a thin highly doped p-type region of hydrogenated amorphous silicon disposed between a Schottky barrier high work function metal and the intrinsic region of hydrogenated amorphous silicon wherein said high work function metal and said thin highly doped p-type region forms a surface barrier junction with the intrinsic amorphous silicon layer. The thickness and concentration of p-type dopants in said p-type region are selected so that said p-type region is fully ionized by the Schottky barrier high work function metal. The thin highly doped p-type region has been found to increase the open circuit voltage and current of the photovoltaic device.

  9. Sensitivity analysis of the add-on price estimate for the silicon web growth process

    NASA Technical Reports Server (NTRS)

    Mokashi, A. R.

    1981-01-01

    The web growth process, a silicon-sheet technology option, developed for the flat plate solar array (FSA) project, was examined. Base case data for the technical and cost parameters for the technical and commercial readiness phase of the FSA project are projected. The process add on price, using the base case data for cost parameters such as equipment, space, direct labor, materials and utilities, and the production parameters such as growth rate and run length, using a computer program developed specifically to do the sensitivity analysis with improved price estimation are analyzed. Silicon price, sheet thickness and cell efficiency are also discussed.

  10. Sensitivity analysis of add-on price estimate for select silicon wafering technologies

    NASA Technical Reports Server (NTRS)

    Mokashi, A. R.

    1982-01-01

    The cost of producing wafers from silicon ingots is a major component of the add-on price of silicon sheet. Economic analyses of the add-on price estimates and their sensitivity internal-diameter (ID) sawing, multiblade slurry (MBS) sawing and fixed-abrasive slicing technique (FAST) are presented. Interim price estimation guidelines (IPEG) are used for estimating a process add-on price. Sensitivity analysis of price is performed with respect to cost parameters such as equipment, space, direct labor, materials (blade life) and utilities, and the production parameters such as slicing rate, slices per centimeter and process yield, using a computer program specifically developed to do sensitivity analysis with IPEG. The results aid in identifying the important cost parameters and assist in deciding the direction of technology development efforts.

  11. Fabrication of carbon-coated silicon nanowires and their application in dye-sensitized solar cells.

    PubMed

    Kim, Junhee; Lim, Jeongmin; Kim, Minsoo; Lee, Hae-Seok; Jun, Yongseok; Kim, Donghwan

    2014-11-12

    We report the fabrication of silicon/carbon core/shell nanowire arrays using a two-step process, involving electroless metal deposition and chemical vapor deposition. In general, foreign shell materials that sheath core materials change the inherent characteristics of the core materials. The carbon coating functionalized the silicon nanowire arrays, which subsequently showed electrocatalytic activities for the reduction of iodide/triiodide. This was verified by cyclic voltammetry and electrochemical impedance spectroscopy. We employed the carbon-coated silicon nanowire arrays in dye-sensitized solar cells as counter electrodes. We optimized the carbon shells to maximize the photovoltaic performance of the resulting devices, and subsequently, a peak power conversion efficiency of 9.22% was achieved. PMID:25319204

  12. Triplet excitons as sensitive spin probes for structure analysis of extended defects in microcrystalline silicon

    NASA Astrophysics Data System (ADS)

    Meier, Christoph; Teutloff, Christian; Behrends, Jan; Bittl, Robert; Astakhov, Oleksandr; Lips, Klaus

    2016-07-01

    Electrically detected magnetic resonance (EDMR) spectroscopy is employed to study the influence of triplet excitons on the photocurrent in state-of-the-art microcrystalline silicon thin-film solar cells. These triplet excitons are used as sensitive spin probes for the investigation of their electronic and nuclear environment in this mixed-phase material. According to low-temperature EDMR results obtained from solar cells with different silicon that give rise to shallow states in the silicon band gap. The excitons possess a rather delocalized wave function, couple to electron spins in conduction band tail states nearby, and take part in a spin-dependent recombination process. Our study shows that extended defects such as grain boundaries or stacking faults in the crystalline part of the material act as charge carrier traps that can influence the material conductivity.

  13. Resonance ionization of sputtered atoms: Quantitative analysis in the near-surface region of silicon wafers

    NASA Astrophysics Data System (ADS)

    Calaway, W. F.; Spiegel, D. R.; Marshall, A. H.; Downey, S. W.; Pellin, M. J.

    1997-02-01

    The unambiguous identification and quantification of low levels of metallic impurities on Si wafers are difficult problems due to the rapidly changing chemical activity near the surface. Air-exposed Si surfaces typically possess a native oxide layer several atoms thick plus a top monolayer of various silicon-containing molecules. Resonance ionization spectroscopy (RIS) used for postionization in secondary neutral mass spectrometry (SNMS) is uniquely suited to this task. The high sensitivity of this technique allows detection of metals at parts per billion levels with monolayer sensitivity. The high selectivity of RIS allows unambiguous identification of elements, while the reduced matrix effects of SNMS allow quantification of the photoionized element. Characterization of Si surfaces using RIS/SNMS has been explored by measuring the concentration profiles of Ca in the near-surface region of Si wafers of varying degrees of cleanliness. Calcium detection can be problematic due to the isobaric interference with SiC, particularly in the near-surface region during fabrication of devices due to the use of organic photoresist. Three different resonance ionization schemes for Ca have been examined and compared for effectiveness by calculating detection limits for Ca in Si in the chemically active near-surface region.

  14. Enhancing the far-UV sensitivity of silicon CMOS imaging arrays

    NASA Astrophysics Data System (ADS)

    Retherford, K. D.; Bai, Yibin; Ryu, Kevin K.; Gregory, J. A.; Welander, Paul B.; Davis, Michael W.; Greathouse, Thomas K.; Winter, Gregory S.; Suntharalingam, Vyshnavi; Beletic, James W.

    2014-07-01

    We report our progress toward optimizing backside-illuminated silicon PIN CMOS devices developed by Teledyne Imaging Sensors (TIS) for far-UV planetary science applications. This project was motivated by initial measurements at Southwest Research Institute (SwRI) of the far-UV responsivity of backside-illuminated silicon PIN photodiode test structures described in Bai et al., SPIE, 2008, which revealed a promising QE in the 100-200 nm range as reported in Davis et al., SPIE, 2012. Our effort to advance the capabilities of thinned silicon wafers capitalizes on recent innovations in molecular beam epitaxy (MBE) doping processes. Key achievements to date include: 1) Representative silicon test wafers were fabricated by TIS, and set up for MBE processing at MIT Lincoln Laboratory (LL); 2) Preliminary far-UV detector QE simulation runs were completed to aid MBE layer design; 3) Detector fabrication was completed through the pre-MBE step; and 4) Initial testing of the MBE doping process was performed on monitoring wafers, with detailed quality assessments. Early results suggest that potential challenges in optimizing the UV-sensitivity of silicon PIN type CMOS devices, compared with similar UV enhancement methods established for CCDs, have been mitigated through our newly developed methods. We will discuss the potential advantages of our approach and briefly describe future development steps.

  15. High-Sensitivity X-ray Polarimetry with Amorphous Silicon Active-Matrix Pixel Proportional Counters

    NASA Technical Reports Server (NTRS)

    Black, J. K.; Deines-Jones, P.; Jahoda, K.; Ready, S. E.; Street, R. A.

    2003-01-01

    Photoelectric X-ray polarimeters based on pixel micropattern gas detectors (MPGDs) offer order-of-magnitude improvement in sensitivity over more traditional techniques based on X-ray scattering. This new technique places some of the most interesting astronomical observations within reach of even a small, dedicated mission. The most sensitive instrument would be a photoelectric polarimeter at the focus of 2 a very large mirror, such as the planned XEUS. Our efforts are focused on a smaller pathfinder mission, which would achieve its greatest sensitivity with large-area, low-background, collimated polarimeters. We have recently demonstrated a MPGD polarimeter using amorphous silicon thin-film transistor (TFT) readout suitable for the focal plane of an X-ray telescope. All the technologies used in the demonstration polarimeter are scalable to the areas required for a high-sensitivity collimated polarimeter. Leywords: X-ray polarimetry, particle tracking, proportional counter, GEM, pixel readout

  16. Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects.

    PubMed

    Grant, Nicholas E

    2016-01-01

    A procedure to measure the bulk lifetime (>100 µsec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (<10(12) cm(-3)). PMID:26779939

  17. Improving picogram mass sensitivity via frequency doubling in coupled silicon micro-cantilevers

    NASA Astrophysics Data System (ADS)

    Wang, Dong F.; Du, Xu; Wang, Xin; Ikehara, Tsuyoshi; Maeda, Ryutaro

    2016-01-01

    Two geometrically different cantilevers, with primary frequencies of 182.506 kHz (u-shaped cantilever for sensing) and 372.503 kHz (rectangular cantilever for detecting), were coupled by two symmetrical coupling overhangs for oscillation-based mass sensing verification with phase-locking. Based on a lumped element model, a theoretical expression, containing a nonlinear spring constant and a term corresponding to the effect of the coupling spring, was proposed to consider the factors influencing the entrainment range, which is defined as a plateau with a frequency ratio (resonant frequency of rectangular cantilever to that of u-shaped cantilever) of 2.000 in present study. A picogram order mass sensing by applying a polystyrene microsphere as a small mass perturbation onto the tip of the u-shaped cantilever was demonstrated. By varying driving voltages, two entrainment regions with and without microsphere were experimentally measured and comparatively shown. At a driving voltage of 1 Vpp, when the u-shaped cantilever was excited at its shifted frequency of 180.29 kHz, the frequency response of the coupled rectangular cantilever had a peak at double the shifted frequency of 360.58 kHz of the u-shaped cantilever. The frequency shift for picogram mass sensing was thus doubled from 2560 Hz to 5133 Hz due to phase-locking. A mass of 3.732 picogram was derived based on the doubled frequency shift corresponding to a calculated mass of 3.771 picogram from measured diameter and reported density. Both experimental demonstration and theoretical discussions from the viewpoint of entrainment range elicits the possibility of increasing the mass sensitivity via phase-locking in the coupled silicon micro-cantilevers.

  18. On the origin of increased sensitivity and mass resolution using silicon masks in MALDI.

    PubMed

    Diologent, Laurent; Franck, Julien; Wisztorski, Maxence; Treizebre, Anthony; Focsa, Cristian; Fournier, Isabelle; Ziskind, Michael

    2014-02-01

    Since its development, MALDI has proved its performance in the analysis of intact biomolecules up to high molecular weights, regardless of their polarity. Sensitivity of MALDI instruments is a key point for breaking the limits of observing biomolecules of lower abundances. Instrumentation is one way to improve sensitivity by increasing ion transmission and using more sensitive detection systems. On the other side, improving MALDI ion production yields would have important outcomes. MALDI ion production is still not well-controlled and, indeed, the amount of ions produced per laser shot with respect to the total volume of desorbed material is very low. This has particular implications for certain applications, such as MALDI MS imaging where laser beam focusing as fine as possible (5-10 μm) is searched in order to reach higher spatial resolution images. However, various studies point out an intrinsic decrease in signal intensity for strong focusing. We have therefore been interested in developing silicon mask systems to decrease an irradiated area by cutting rather than focusing the laser beam and to study the parameters affecting sensitivity using such systems. For this, we systematically examined variation with laser fluence of intensity and spectral resolution in MALDI of standard peptides when using silicon-etched masks of various aperture sizes. These studies demonstrate a simultaneous increase in spectral resolution and signal intensity. Origin of this effect is discussed in the frame of the two-step ionization model. Experimental data in the low fluence range are fitted with an increase of the primary ionization through matrix-silicon edge contact provided by the masks. On the other hand, behavior at higher fluence could be explained by an effect on the secondary ionization via changes in the plume dynamics. PMID:24422461

  19. Highly sensitive silicon crystal torque sensor operating at the thermal noise limit

    NASA Astrophysics Data System (ADS)

    Haiberger, L.; Weingran, M.; Schiller, S.

    2007-02-01

    We describe a sensitive torque detector, based on a silicon single-crystal double-paddle oscillator (DPO). The high Q-factor (˜105 at room temperature and in vacuum) makes DPOs well suited for the detection of weak forces. The limiting sensitivity of a sensor is given by Brownian (thermal) noise if all external disturbances are eliminated. In this case, the minimum detectable force can be decreased by measuring over a time significantly longer than the oscillator's relaxation time. We demonstrate operation in this regime, with integration times of up to 14 h. A resulting torque sensitivity of 2×10-18 N m is reached. Tests are performed to show that the sensor is only affected by thermal noise. The present sensor is well suited for measurements of extremely weak forces, e.g., of gravitational attraction between laboratory masses.

  20. Highly sensitive silicon crystal torque sensor operating at the thermal noise limit

    SciTech Connect

    Haiberger, L.; Weingran, M.; Schiller, S.

    2007-02-15

    We describe a sensitive torque detector, based on a silicon single-crystal double-paddle oscillator (DPO). The high Q-factor ({approx}10{sup 5} at room temperature and in vacuum) makes DPOs well suited for the detection of weak forces. The limiting sensitivity of a sensor is given by Brownian (thermal) noise if all external disturbances are eliminated. In this case, the minimum detectable force can be decreased by measuring over a time significantly longer than the oscillator's relaxation time. We demonstrate operation in this regime, with integration times of up to 14 h. A resulting torque sensitivity of 2x10{sup -18} N m is reached. Tests are performed to show that the sensor is only affected by thermal noise. The present sensor is well suited for measurements of extremely weak forces, e.g., of gravitational attraction between laboratory masses.

  1. Highly sensitive silicon crystal torque sensor operating at the thermal noise limit.

    PubMed

    Haiberger, L; Weingran, M; Schiller, S

    2007-02-01

    We describe a sensitive torque detector, based on a silicon single-crystal double-paddle oscillator (DPO). The high Q-factor (approximately 10(5) at room temperature and in vacuum) makes DPOs well suited for the detection of weak forces. The limiting sensitivity of a sensor is given by Brownian (thermal) noise if all external disturbances are eliminated. In this case, the minimum detectable force can be decreased by measuring over a time significantly longer than the oscillator's relaxation time. We demonstrate operation in this regime, with integration times of up to 14 h. A resulting torque sensitivity of 2 x 10(-18) N m is reached. Tests are performed to show that the sensor is only affected by thermal noise. The present sensor is well suited for measurements of extremely weak forces, e.g., of gravitational attraction between laboratory masses. PMID:17578142

  2. Sensitivity to orthographic familiarity in the occipito-temporal region.

    PubMed

    Bruno, Jennifer Lynn; Zumberge, Allison; Manis, Franklin R; Lu, Zhong-Lin; Goldman, Jason G

    2008-02-15

    The involvement of the left hemisphere occipito-temporal (OT) junction in reading has been established, yet there is current controversy over the region's specificity for reading and the nature of its role in the reading process. Recent neuroimaging findings suggest that the region is sensitive to orthographic familiarity [Kronbichler, M., Bergmann, J., Hutzler, F., Staffen, W., Mair, A., Ladurner, G., Wimmer, H. 2007. Taxi vs. Taksi: on orthographic word recognition in the left ventral occipito-temporal cortex. Journal of Cognitive Neuroscience 19, 1-11], and the present study tested that hypothesis. Using fMRI, the OT region and other regions in the reading network were localized in 28 adult, right-handed participants. The BOLD signal in these regions was measured during a phonological judgment task (i.e., "Does it sound like a word?"). Stimuli included words, pseudohomophones (phonologically familiar yet orthographically unfamiliar), and pseudowords (phonologically and orthographically unfamiliar) that were matched on lexical properties including sublexical orthography. Relative to baseline, BOLD signal in the OT region was greater for pseudohomophones than for words, suggesting that the region is sensitive to orthographic familiarity at the whole-word level. Further contrasts of orthographic frequency within the word condition revealed increased BOLD signal for low- than high-frequency words. Specialization in the OT region for recognition of frequent letter strings may support the development of reading expertise. Additionally, BOLD signal in the OT region correlates positively with reading efficiency, supporting the idea that this region is a skill zone for reading printed words. BOLD signal in the IFG and STG correlates negatively with reading efficiency, indicating that processing effort in these classic phonological regions is inversely related to reading efficiency. PMID:18180168

  3. A carbon nanotubes photoconductive detector for middle and far infrared regions based on porous silicon and a polyamide nylon polymer

    NASA Astrophysics Data System (ADS)

    Saleh, Wasan R.

    2015-06-01

    Sensitive and good response photoconductive detectors working in the middle and far infrared regions were fabricated. These detectors were fabricated based on multi and double walled carbon nanotube films and works at room temperature. The films were deposited on a porous silicon (PSi) nanosurface. The surfaces were functionalized by a thin layer of polyamide nylon polymer to improve the photoresponsivity of the fabricated detectors. The response time of the fabricated MWCNTs-PSi detectors were 30 and 0.22 ms for the middle and far IR region respectively. The functionalisation of the MWCNTs-PSi film surface by the polyamide nylon polymer improved the photoconductive gain, photoresponsivity, and specific conductivity in both MWCNTs-PSi and DWCNTs-PSi detectors. The designed carbon nanotube (CNT) based photodetector has low cost, high sensitivity and reasonable speed for the middle and far IR spectral range without cooling.

  4. Light trapping and plasmonic enhancement in silicon, dye-sensitized and titania solar cells

    NASA Astrophysics Data System (ADS)

    Nhung Tran, Hong; Hieu Nguyen, Van; Nguyen, Bich Ha; Vu, Dinh Lam

    2016-03-01

    The efficiency of a solar cell depends on both the quality of its semiconductor active layer, as well as on the presence of other dielectric and metallic structural components which improve light trapping and exploit plasmonic enhancement. The purpose of this work is to review the results of recent research on light trapping and plasmonic enhancement in three types of solar cells: thin-film silicon solar cells, dye-sensitized solar cells and solid-state titania solar cells. The results of a study on modeling and the design of light trapping components in solar cells are also presented.

  5. The durability of the dye-sensitized solar cell with silicon resin

    NASA Astrophysics Data System (ADS)

    Ki, Hyun Chul; Kim, Seon Hoon; Kim, Doo-Gun; Kim, Tae-Un; Jung, Haeng-Yun; Yoon, Jae-Man

    2015-03-01

    Dye-Sensitized solar cell (DSSC) is expected to be one of the next-generation photovoltaics because of its environment-friendly and low-cost properties. However, commercialization of DSSC is difficult because of the electrolyte leakage. We propose a new thermal curable base on silicon resin. The resin aimed at sealing of DSSC and gives a promising resolution for sealing of practical DSSC. Furthermore, the optimized resin was fabricated into solar cells, which exhibited best durability by retaining 97% of the initial photoelectric conversion efficiency after 1,000 hours tracking test at 80°C.

  6. Sensitivity to Orthographic Familiarity in the Occipito-Temporal Region

    PubMed Central

    Bruno, Jennifer Lynn; Zumberge, Allison; Manis, Franklin R.; Lu, Zhong-Lin; Goldman, Jason G.

    2008-01-01

    The involvement of the left hemisphere occipito-temporal (OT) junction in reading has been established, yet there is current controversy over the region’s specificity for reading and the nature of its role in the reading process. Recent neuroimaging findings suggest that the region is sensitive to orthographic familiarity (Kronbichler et al., 2007), and the present study tested that hypothesis. Using fMRI, the OT region and other regions in the reading network were localized in 28 adult, right-handed participants. The BOLD signal in these regions was measured during a phonological judgment task (i.e., “Does it sound like a word?”). Stimuli included words, pseudohomophones (phonologically familiar yet orthographically unfamiliar), and pseudowords (phonologically and orthographically unfamiliar) that were matched on lexical properties including sublexical orthography. Relative to baseline, BOLD signal in the OT region was greater for pseudohomophones than for words, suggesting that the region is sensitive to orthographic familiarity at the whole-word level. Further contrasts of orthographic frequency within the word condition revealed increased BOLD signal for low- than high-frequency words. Specialization in the OT area for recognition of frequent letter strings may support the development of reading expertise. Additionally, BOLD signal in the OT region correlates positively with reading efficiency, supporting the idea that this region is a skill zone for reading printed words. BOLD signal in the IFG and STG correlate negatively with reading efficiency, indicating that processing effort in these classic phonological regions is inversely related to reading efficiency. PMID:18180168

  7. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    SciTech Connect

    Yan, Hai Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  8. Ultra-sensitive silicon photonic current sensor using a ring resonator

    NASA Astrophysics Data System (ADS)

    Wei, Bing; Zhao, Changyun; Wang, Gencheng; Dai, Tingge; Wang, Yuehai; Yang, Jianyi; Li, Yubo

    2016-08-01

    We proposed and experimentally investigated a compact and ultra-sensitive integrated photonic current sensor based on a silicon ring resonator in this paper. The current flowing through the integrated resistive TiN heater produces the Joule’s heat and changes the temperature, which results in the change of refractive index and physical dimensions of the ring. An optical spectrum analyzer is used to monitor the resonant wavelength shift of the ring. The experiment results show that the sensor achieves an ultra-high sensitivity of 6.8 × 104 nm A‑2 and good linearity between real-time current and wavelength shift in the test range of 0–10 mA.

  9. Ultra-sensitive detection of adipocytokines with CMOS-compatible silicon nanowire arrays

    NASA Astrophysics Data System (ADS)

    Pui, Tze-Sian; Agarwal, Ajay; Ye, Feng; Tou, Zhi-Qiang; Huang, Yinxi; Chen, Peng

    2009-09-01

    Perfectly aligned arrays of single-crystalline silicon nanowires were fabricated using top-down CMOS-compatible techniques. We demonstrate that these nanowire devices are able to detect adipocytokines secreted by adipose cells with femtomolar sensitivity, high specificity, wide detection range, and ability for parallel monitoring. The nanowire sensors also provide a novel tool to reveal the poorly understood signaling mechanisms of these newly recognized signaling molecules, as well as their relevance in common diseases such as obesity and diabetes.Perfectly aligned arrays of single-crystalline silicon nanowires were fabricated using top-down CMOS-compatible techniques. We demonstrate that these nanowire devices are able to detect adipocytokines secreted by adipose cells with femtomolar sensitivity, high specificity, wide detection range, and ability for parallel monitoring. The nanowire sensors also provide a novel tool to reveal the poorly understood signaling mechanisms of these newly recognized signaling molecules, as well as their relevance in common diseases such as obesity and diabetes. Electronic supplementary information (ESI) available: Process diagram of nanowire fabrication; specificity of nanowire detection; induced differentiation of 3T3-L1 cells. See DOI: 10.1039/b9nr00092e

  10. An improved method of energy calibration for position-sensitive silicon detectors

    NASA Astrophysics Data System (ADS)

    Sun, Ming-Dao; Huang, Tian-Heng; Liu, Zhong; Ding, Bing; Yang, Hua-Bin; Zhang, Zhi-Yuan; Wang, Jian-Guo; Ma, Long; Yu, Lin; Wang, Yong-Sheng; Gan, Zai-Guo; Xiao-Hong, Zhou

    2016-04-01

    Energy calibration of resistive charge division-based position-sensitive silicon detectors is achieved by parabolic fitting in the traditional method, where the systematic variations of vertex and curvature of the parabola with energy must be considered. In this paper we extend the traditional method in order to correct the fitting function, simplify the procedure of calibration and improve the experimental data quality. Instead of a parabolic function as used in the traditional method, a new function describing the relation of position and energy is introduced. The energy resolution of the 8.088 MeV α decay of 213Rn is determined to be about 87 keV (FWHM), which is better than the result of the traditional method, 104 keV (FWHM). The improved method can be applied to the energy calibration of resistive charge division-based position-sensitive silicon detectors with various performances. Supported by ‘100 Person Project’ of the Chinese Academy of Sciences and the National Natural Science Foundation of China (11405224 and 11435014)

  11. A sensitive charge scanning probe based on silicon single electron transistor

    NASA Astrophysics Data System (ADS)

    Lina, Su; Xinxing, Li; Hua, Qin; Xiaofeng, Gu

    2016-04-01

    Single electron transistors (SETs) are known to be extremely sensitive electrometers owing to their high charge sensitivity. In this work, we report the design, fabrication, and characterization of a silicon-on-insulator-based SET scanning probe. The fabricated SET is located about 10 μm away from the probe tip. The SET with a quantum dot of about 70 nm in diameter exhibits an obvious Coulomb blockade effect measured at 4.1 K. The Coulomb blockade energy is about 18 meV, and the charge sensitivity is in the order of 10‑5‑10‑3 e/Hz1/2. This SET scanning probe can be used to map charge distribution and sense dynamic charge fluctuation in nanodevices or circuits under test, realizing high sensitivity and high spatial resolution charge detection. Project supported by the Instrument Developing Project of the Chinese Academy of Sciences (No. YZ201152), the National Natural Science Foundation of China (No. 11403084), the Fundamental Research Funds for Central Universities (Nos. JUSRP51510, JUDCF12032), and the Graduate Student Innovation Program for Universities of Jiangsu Province (No. CXLX12_0724).

  12. Temperature sensitivity of silicon nitride nanocoated long-period gratings working in various surrounding media

    NASA Astrophysics Data System (ADS)

    Smietana, M.; Bock, W. J.; Mikulic, P.

    2011-11-01

    This paper presents the temperature sensing properties of a silicon nitride (SiNx) nanocoated long-period grating (LPG). A high-temperature, radio-frequency plasma-enhanced chemical-vapor-deposited SiNx nanocoating was applied to tune the external refractive index (RI) sensitivity of LPGs written with UV and electric arc techniques in boron co-doped and standard germanium doped fibers, respectively. The technique allows for deposition of good quality, hard and wear-resistant nanofilms as are required for optical sensors. Thanks to the high-RI SiNx nanocoating, which is less than 90 nm thick, it is possible to reduce RI sensitivity over a wide range (from nD = 1.333 to 1.479), simultaneously decreasing its cross-sensitivity to temperature. For the presented nanocoated LPGs, the temperature effect on resonance wavelength is linear and slightly dependent on the thermo-optic coefficient of the surrounding liquid. The other advantage of the nanocoating is that it makes the resonance clearly visible in the whole investigated external RI range. To the best of our knowledge, this work presents for the first time a nanocoating able to simultaneously tune the RI sensitivity and enable temperature measurements in high-RI liquids applied to LPGs.

  13. Optical temperature sensor with enhanced sensitivity by employing hybrid waveguides in a silicon Mach-Zehnder interferometer.

    PubMed

    Guan, Xiaowei; Wang, Xiaoyan; Frandsen, Lars H

    2016-07-25

    We report on a novel design of an on-chip optical temperature sensor based on a Mach-Zehnder interferometer configuration where the two arms consist of hybrid waveguides providing opposite temperature-dependent phase changes to enhance the temperature sensitivity of the sensor. The sensitivity of the fabricated sensor with silicon/polymer hybrid waveguides is measured to be 172 pm/°C, which is two times larger than a conventional all-silicon optical temperature sensor (~80 pm/°C). Moreover, a design with silicon/titanium dioxide hybrid waveguides is by calculation expected to have a sensitivity as high as 775 pm/°C. The proposed design is found to be design-flexible and robust to fabrication errors. PMID:27464088

  14. Effect of biointerfacing linker chemistries on the sensitivity of silicon nanowires for protein detection.

    PubMed

    Dorvel, Brian; Reddy, Bobby; Bashir, Rashid

    2013-10-15

    Point-of-care diagnostics show promise in removing reliance on centralized lab testing facilities and may help increase both the survival rate for infectious diseases as well as monitoring of chronic illnesses. CMOS compatible diagnostic platforms are currently being considered as possible solutions as they can be easily miniaturized and can be cost-effective. Top-down fabricated silicon nanowires are a CMOS-compatible technology which have demonstrated high sensitivities in detecting biological analytes, such as proteins, DNA, and RNA. However, the reported response of nanowires to these analytes has varied widely since several different functionalization protocols have been attempted with little characterization and comparison. Here we report protocols for fabrication and functionalization of silicon nanowires which yield highly stable nanowires in aqueous solutions and limits of detection to ∼1 pg/mL of the model protein used in the study. A thorough characterization was done into optimizing the release of the silicon nanowires using combined dry and wet etch techniques, which yielded nanowires that could be directly compared to increase output statistics. Moreover, a range of different linker chemistries were tried for reacting the primary antibody, and its response to target and nonspecific antigens, with polyethylene glycol based linker BS(PEG)5 providing the best response. Consequently, this chemistry was used to characterize different oxide thicknesses and their responses to the mouse IgG antigen, which with the smallest oxide thickness yielded 0.1-1 pg/mL limits of detection and a dynamic range over 3 orders of magnitude. PMID:24040958

  15. Self-aligned nanoforest in silicon nanowire for sensitive conductance modulation.

    PubMed

    Seol, Myeong-Lok; Ahn, Jae-Hyuk; Choi, Ji-Min; Choi, Sung-Jin; Choi, Yang-Kyu

    2012-11-14

    A self-aligned and localized nanoforest structure is constructed in a top-down fabricated silicon nanowire (SiNW). The surface-to-volume ratio (SVR) of the SiNW is enhanced due to the local nanoforest formation. The conductance modulation property of the SiNWs, which is an important characteristic in sensor and charge transfer based applications, can be largely enhanced. For the selective modification of the channel region, localized Joule-heating and subsequent metal-assisted chemical etching (mac-etch) are employed. The nanoforest is formed only in the channel region without misalignment due to the self-aligned process of Joule-heating. The modified SiNW is applied to a porphyrin-silicon hybrid device to verify the enhanced conductance modulation. The charge transfer efficiency between the porphyrin and the SiNW, which is caused by external optical excitation, is clearly increased compared to the initial SiNW. The effect of the local nanoforest formation is enhanced when longer etching times and larger widths are used. PMID:23066892

  16. Position-sensitive spectral splitting with a plasmonic nanowire on silicon chip

    PubMed Central

    Hu, Qing; Xu, Di-Hu; Zhou, Yu; Peng, Ru-Wen; Fan, Ren-Hao; Fang, Nicholas X.; Wang, Qian-Jin; Huang, Xian-Rong; Wang, Mu

    2013-01-01

    On-chip nanophotonics serves as the foundation for the new generation of information technology, but it is challenged by the diffraction limit of light. With the capabilities of confining light into (deep) subwavelength volumes, plasmonics makes it possible to dramatically miniaturize optical devices so as to integrate them into silicon chips. Here we demonstrate that by cascading nano-corrugation gratings with different periodicities on silver nanowires atop silicon, different colors can be spatially separated and chronologically released at different grating junctions. The released light frequency depends on the grating arrangement and corrugation periodicities. Hence the nanowire acts as a spectral splitter for sorting/demultiplexing photons at different nano-scale positions with a ten-femtosecond-level interval. Such nanowires can be constructed further into compact 2D networks or circuits. We believe that this study provides a new and promising approach for realizing spatiotemporal-sensitive spectral splitting and optical signal processing on nanoscales, and for general integration of nanophotonics with microelectronics. PMID:24172838

  17. Sensitivity of regional climate to global temperature and forcing

    NASA Astrophysics Data System (ADS)

    Tebaldi, Claudia; O'Neill, Brian; Lamarque, Jean-François

    2015-07-01

    The sensitivity of regional climate to global average radiative forcing and temperature change is important for setting global climate policy targets and designing scenarios. Setting effective policy targets requires an understanding of the consequences exceeding them, even by small amounts, and the effective design of sets of scenarios requires the knowledge of how different emissions, concentrations, or forcing need to be in order to produce substantial differences in climate outcomes. Using an extensive database of climate model simulations, we quantify how differences in global average quantities relate to differences in both the spatial extent and magnitude of climate outcomes at regional (250-1250 km) scales. We show that differences of about 0.3 °C in global average temperature are required to generate statistically significant changes in regional annual average temperature over more than half of the Earth’s land surface. A global difference of 0.8 °C is necessary to produce regional warming over half the land surface that is not only significant but reaches at least 1 °C. As much as 2.5 to 3 °C is required for a statistically significant change in regional annual average precipitation that is equally pervasive. Global average temperature change provides a better metric than radiative forcing for indicating differences in regional climate outcomes due to the path dependency of the effects of radiative forcing. For example, a difference in radiative forcing of 0.5 W m-2 can produce statistically significant differences in regional temperature over an area that ranges between 30% and 85% of the land surface, depending on the forcing pathway.

  18. Micro Cantilever Movement Detection with an Amorphous Silicon Array of Position Sensitive Detectors

    PubMed Central

    Contreras, Javier; Costa, Daniel; Pereira, Sonia; Fortunato, Elvira; Martins, Rodrigo; Wierzbicki, Rafal; Heerlein, Holger; Ferreira, Isabel

    2010-01-01

    The movement of a micro cantilever was detected via a self constructed portable data acquisition prototype system which integrates a linear array of 32 1D amorphous silicon position sensitive detectors (PSD). The system was mounted on a microscope using a metal structure platform and the movement of the 30 μm wide by 400 μm long cantilever was tracked by analyzing the signals acquired by the 32 sensor array electronic readout system and the relevant data algorithm. The obtained results show a linear behavior of the photocurrent relating X and Y movement, with a non-linearity of about 3%, a spatial resolution of less than 2 μm along the lateral dimension of the sensor as well as of less than 3 μm along the perpendicular dimension of the sensor, when detecting just the micro-cantilever, and a spatial resolution of less than 1 μm when detecting the holding structure. PMID:22163648

  19. Magnetoresistive polyaniline-silicon carbide metacomposites: plasma frequency determination and high magnetic field sensitivity.

    PubMed

    Gu, Hongbo; Guo, Jiang; Khan, Mojammel Alam; Young, David P; Shen, T D; Wei, Suying; Guo, Zhanhu

    2016-07-20

    The Drude model modified by Debye relaxation time was introduced to determine the plasma frequency (ωp) in the surface initiated polymerization (SIP) synthesized β-silicon carbide (β-SiC)/polyaniline (PANI) metacomposites. The calculated plasma frequency for these metacomposites with different loadings of β-SiC nanoparticles was ranging from 6.11 × 10(4) to 1.53 × 10(5) rad s(-1). The relationship between the negative permittivity and plasma frequency indicates the existence of switching frequency, at which the permittivity was changed from negative to positive. More interestingly, the synthesized non-magnetic metacomposites, observed to follow the 3-dimensional (3-D) Mott variable range hopping (VRH) electrical conduction mechanism, demonstrated high positive magnetoresistance (MR) values of up to 57.48% and high MR sensitivity at low magnetic field regimes. PMID:27386820

  20. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array.

    PubMed

    Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-Beom; Choi, Heon-Jin

    2016-12-01

    In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes. PMID:27448026

  1. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array

    NASA Astrophysics Data System (ADS)

    Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-beom; Choi, Heon-Jin

    2016-07-01

    In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes.

  2. Silicon nanowire biosensors for detection of cardiac troponin I (cTnI) with high sensitivity.

    PubMed

    Kim, Kihyun; Park, Chanoh; Kwon, Donghoon; Kim, Donghoon; Meyyappan, M; Jeon, Sangmin; Lee, Jeong-Soo

    2016-03-15

    We have demonstrated highly sensitive and label-free detection of cardiac troponin I (cTnI), a biomarker for diagnosis of acute myocardial infarction, using silicon nanowire field-effect transistors. A honeycomb-like structure is utilized for nanowire configuration to offer improved electrical performance and increased sensing area. The fabricated devices show n-type behavior with a relatively high ON-OFF current ratio, small sub-threshold swing and low gate leakage current. Monoclonal antibodies for cTnI were covalently immobilized on the nanowire surface and the attachment of antibodies is clearly visualized by atomic force microscope. The sensitivity with various concentrations of buffer solution was also investigated in order to determine the optimal buffer condition. The devices exhibit highest sensitivity under buffer solutions with low ion concentration. In addition, the detection limit of the sensor is as low as ~5 pg/mL, the lowest reported in the literature to date and nearly an order of magnitude smaller than the suggested threshold limit. The fabricated devices demonstrate a good selectivity for detecting cTnI. PMID:26496224

  3. Current economic and sensitivity analysis for ID slicing of 4 inch and 6 inch diameter silicon ingots for photovoltaic applications

    NASA Technical Reports Server (NTRS)

    Roberts, E. G.; Johnson, C. M.

    1982-01-01

    The economics and sensitivities of slicing large diameter silicon ingots for photovoltaic applications were examined. Current economics and slicing add on cost sensitivities are calculated using variable parameters for blade life, slicing yield, and slice cutting speed. It is indicated that cutting speed has the biggest impact on slicing add on cost, followed by slicing yield, and by blade life as the blade life increases.

  4. Characterization of the interface region during the agglomeration of silicon nanocrystals in silicon dioxide

    NASA Astrophysics Data System (ADS)

    Pi, X. D.; Coleman, P. G.; Harding, R.; Davies, G.; Gwilliam, R. M.

    2004-06-01

    Si nanocrystals embedded in thermally grown SiO2 have been annealed at temperatures between 400 and 900 °C in a variety of atmospheres. Positron annihilation spectroscopy has been employed to study changes in the interface regions between nanocrystalline Si (nc-Si) and SiO2 with the support of photoluminescence measurements. We find that nitrogen and oxygen are trapped in the voids around nc-Si at low annealing temperatures. High-temperature annealing during the formation of nc-Si causes hydrogen originally residing in the SiO2/substrate region to enter the SiO2 structure. Hydrogen diffuse back to the SiO2/substrate region on annealing in vacuum at 400 °C because no other impurities block its diffusion channels. At annealing temperatures above 700 °C, both nitrogen and oxygen react with nc-Si, resulting in a volume increase. This introduces stress in the SiO2 matrix, which is relaxed by the shrinkage of its intrinsic open volume. The present data suggest that nitrogen suppresses Si diffusion in SiO2, so that the agglomeration of nc-Si is slower during annealing in nitrogen than in oxygen or vacuum.

  5. Features of the electroluminescence spectra of quantum-confined silicon p{sup +}-n heterojunctions in the infrared spectral region

    SciTech Connect

    Bagraev, N. T.; Klyachkin, L. E.; Kuzmin, R. V. Malyarenko, A. M.; Mashkov, V. A.

    2013-11-15

    The results of studying the characteristics of optical emission in various regions of quantum-confined silicon p{sup +}-n heterojunctions heavily doped with boron are analyzed. The results obtained allow one to conclude that near-infrared electroluminescence arises near the heterointerface between the nanostructured wide-gap silicon p{sup +}-barrier heavily doped with boron and n-type silicon (100), the formation of which included the active involvement of boron dipole centers.

  6. Poly(3-methylthiophene)-based porous silicon substrates as a urea-sensitive electrode

    NASA Astrophysics Data System (ADS)

    Jin, Joon-Hyung; Min, Nam Ki; Hong, Suk-In

    2006-08-01

    Poly(3-methylthiophene) (P3MT)-based porous silicon (PS) substrates were fabricated and characterized by cyclic voltammetry, scanning electron microscopy, and auger electron spectroscopy. After doping urease (Urs) into the polymeric matrix, sensitivity and physicochemical properties of the P3MT-based PS substrate was investigated compared to planar silicon (PLS) and bulk Pt substrates. PS substrate was formed by electrochemical anodization in an etching solution composed of HF, H 2O, and ethanol. Subsequently, Ti and Pt thin-films were sputtered on the PS substrate. Effective working electrode area ( Aeff) of the Pt-deposited PS substrate was determined from a redox reaction of Fe(CN) 63-/Fe(CN) 64- redox couple in which nearly reversible cyclic voltammograms were obtained. The ip versus v1/2 plots showed that Aeff of the PS-based Pt thin-film electrode was 1.62 times larger than that of the PLS-based electrode. Electropolymerization of P3MT on both types of electrodes were carried out by the anodic potential scanning under the given potential range. And then, urease molecules were doped to the P3MT film by the chronoamperometry. Direct electrochemistry of a Urs/P3MT/Pt/Ti/PS electrode in an acetonitrile solution containing 0.1 mol/L NaClO 4 was introduced compared to a P3MT/Pt/Ti/PS electrode at scan rates of 10 mV s -1, 50 mV s -1, and 100 mV s -1. Amperometric sensitivity of the Urs/P3MT/Pt/Ti/PS electrode was ca. 1.67 μA mM -1 per projected unit square centimeter, and that of the Urs/P3MT/Pt/Ti/PLS electrode was ca. 1.02 μA mM -1 per projected unit square centimeter in a linear range of 1-100 mM urea concentrations. 1.6 times of sensitivity increase was coincident with the results from cyclic voltammetrc analysis. Surface morphology from scanning electron microscopy (SEM) images of Pt-deposited PS electrodes before and after the coating of Urs-doped P3MT films showed that pore diameter and depth were 2 μm and 10 μm, respectively. Multilayered

  7. Sensitization of the Nociceptive System in Complex Regional Pain Syndrome

    PubMed Central

    Diedrichs, Carolina; Baron, Ralf; Gierthmühlen, Janne

    2016-01-01

    Background Complex regional pain syndrome type I (CRPS-I) is characterized by sensory, motor and autonomic abnormalities without electrophysiological evidence of a nerve lesion. Objective Aims were to investigate how sensory, autonomic and motor function change in the course of the disease. Methods 19 CRPS-I patients (17 with acute, 2 with chronic CRPS, mean duration of disease 5.7±8.3, range 1–33 months) were examined with questionnaires (LANSS, NPS, MPI, Quick DASH, multiple choice list of descriptors for sensory, motor, autonomic symptoms), motor and autonomic tests as well as quantitative sensory testing according to the German Research Network on Neuropathic Pain at two visits (baseline and 36±10.6, range 16–53 months later). Results CRPS-I patients had an improvement of sudomotor and vasomotor function, but still a great impairment of sensory and motor function upon follow-up. Although pain and mechanical detection improved upon follow-up, thermal and mechanical pain sensitivity increased, including the contralateral side. Increase in mechanical pain sensitivity and loss of mechanical detection were associated with presence of ongoing pain. Conclusions The results demonstrate that patients with CRPS-I show a sensitization of the nociceptive system in the course of the disease, for which ongoing pain seems to be the most important trigger. They further suggest that measured loss of function in CRPS-I is due to pain-induced hypoesthesia rather than a minimal nerve lesion. In conclusion, this article gives evidence for a pronociceptive pain modulation profile developing in the course of CRPS and thus helps to assess underlying mechanisms of CRPS that contribute to the maintenance of patients’ pain and disability. PMID:27149519

  8. Silicon microdosimetry.

    PubMed

    Agosteo, Stefano; Pola, Andrea

    2011-02-01

    Silicon detectors are being studied as microdosemeters since they can provide sensitive volumes of micrometric dimensions. They can be applied for assessing single-event effects in electronic instrumentation exposed to complex fields around high-energy accelerators or in space missions. When coupled to tissue-equivalent converters, they can be used for measuring the quality of radiation therapy beams or for dosimetry. The use of micrometric volumes avoids the contribution of wall effects to the measured spectra. Further advantages of such detectors are their compactness, cheapness, transportability and a low sensitivity to vibrations. The following problems need to be solved when silicon devices are used for microdosimetry: (i) the sensitive volume has to be confined in a region of well-known dimensions; (ii) the electric noise limits the minimum detectable energy; (iii) corrections for tissue-equivalency should be made; (iv) corrections for shape equivalency should be made when referring to a spherical simulated site of tissue; (v) the angular response should be evaluated carefully; (vi) the efficiency of a single detector of micrometric dimensions is very poor and detector arrays should be considered. Several devices have been proposed as silicon microdosemeters, based on different technologies (telescope detectors, silicon on insulator detectors and arrays of cylindrical p-n junctions with internal amplification), in order to satisfy the issues mentioned above. PMID:21112892

  9. Sensitivity of Regional Climate to Deforestation in the Amazon Basin

    NASA Technical Reports Server (NTRS)

    Eltahir, Elfatih A. B.; Bras, Rafael L.

    1994-01-01

    The deforestation results in several adverse effect on the natural environment. The focus of this paper is on the effects of deforestation on land-surface processes and regional climate of the Amazon basin. In general, the effect of deforestation on climate are likely to depend on the scale of the defrosted area. In this study, we are interested in the effects due to deforestation of areas with a scale of about 250 km. Hence, a meso-scale climate model is used in performing numerical experiments on the sensitivity of regional climate to deforestation of areas with that size. It is found that deforestation results in less net surface radiation, less evaporation, less rainfall, and warmer surface temperature. The magnitude of the of the change in temperature is of the order 0.5 C, the magnitudes of the changes in the other variables are of the order of IO%. In order to verify some of he results of the numerical experiments, the model simulations of net surface radiation are compared to recent observations of net radiation over cleared and undisturbed forest in the Amazon. The results of the model and the observations agree in the following conclusion: the difference in net surface radiation between cleared and undisturbed forest is, almost, equally partioned between net solar radiation and net long-wave radiation. This finding contributes to our understanding of the basic physics in the deforestation problem.

  10. Regional Sensitivity to Neuroinflammation: In Vivo and In Vitro Studies

    SciTech Connect

    Liraz-Zaltsman, S.; Biegon, A.; Liraz-Zaltsman, S.; Alexandrovich, A.G.; Trembovler, V.; Fishbein, I.; Yaka, R.; Shohami, E.; Biegon, A.

    2010-11-23

    Neuroinflammation is involved in several acute-onset neuropathologies such as meningitis, encephalitis, stroke, and traumatic brain injury as well as in neurodegenerative diseases. All of these patholologies are associated with cognitive deficits. Using a model of pure neuroinflammation (intracisternal injection of endotoxin in mice), we tested the hypothesis that brain regions involved in cognition are the most vulnerable to inflammatory insults, and this vulnerability is an inherent property of neocortical neurons. Mice (n = 10/group) injected with endotoxin (LPS) or saline in the cisterna magna underwent neurobehavioral and cognitive testing followed by quantitative autoradiographic assessment of regional neuroinflammation with [3H]PK11195, an established marker of microgliosis. In parallel, cocultures of cortical and striatal neurons taken from embryonic day 19 rat embryos or postnatal day 1 mice expressing green fluorescent protein were exposed for 24 h to the proinflammatory cytokine TNFalpha, glutamate, or a combination of the two agents. LPS-treated mice exhibited significant deficits in memory and significant increases in specific PK11195 binding in cortical and hippocampal regions, but not in striatum. Cultured neurons of cortical origin showed significantly lower survival rate relative to striatal neurons in response to TNFalpha, glutamate, or a combination of the two agents. Furthermore, TNFalpha exerted neuroprotective rather than neurotoxic effects in the striatal but not in the cortical neurons. These results suggest that the cortex is inherently more sensitive than the striatum to the deleterious effects of neuroinflammation, and may offer an explanation for the preponderance of cognitive deficits in neuropathologies with a neuroinflammatory component.

  11. Notch-sensitive fracture behavior of a silicon carbide fiber-reinforced glass-ceramic at elevated temperatures

    SciTech Connect

    Kahraman, R.; Sunar, M.

    1998-02-01

    The effect on high-temperature embrittlement of introducing a through-thickness notch in a multidirectional silicon carbide fiber-reinforced calcium-aluminosilicate glass-ceramic composite was investigated through tensile testing, microdebonding, and light and scanning electron microscopy techniques. The fracture mechanism of the composite changed from notch insensitive at room temperature to notch sensitive at elevated temperatures due to increased fiber-matrix bond strength caused by oxidation effects at interfaces exposed to the oxidative environment. Stress concentration and bending effects at the notch tip resulted in growth of the notch through fibers in a planar fashion covering the entire fracture surface. This was contrary to the case of an unnotched composite, for which two distinct fracture surface regions were observed as planar embrittlement zones at the periphery and fibrous at the center. Cracks in the notched composite were more closed relative to those in the unnotched one, except at the notch tip. Concentration of the stress at the notch tip increased the high-temperature embrittlement effect on the composite.

  12. Microglial brain region-dependent diversity and selective regional sensitivities to aging.

    PubMed

    Grabert, Kathleen; Michoel, Tom; Karavolos, Michail H; Clohisey, Sara; Baillie, J Kenneth; Stevens, Mark P; Freeman, Tom C; Summers, Kim M; McColl, Barry W

    2016-03-01

    Microglia have critical roles in neural development, homeostasis and neuroinflammation and are increasingly implicated in age-related neurological dysfunction. Neurodegeneration often occurs in disease-specific, spatially restricted patterns, the origins of which are unknown. We performed to our knowledge the first genome-wide analysis of microglia from discrete brain regions across the adult lifespan of the mouse, and found that microglia have distinct region-dependent transcriptional identities and age in a regionally variable manner. In the young adult brain, differences in bioenergetic and immunoregulatory pathways were the major sources of heterogeneity and suggested that cerebellar and hippocampal microglia exist in a more immune-vigilant state. Immune function correlated with regional transcriptional patterns. Augmentation of the distinct cerebellar immunophenotype and a contrasting loss in distinction of the hippocampal phenotype among forebrain regions were key features during aging. Microglial diversity may enable regionally localized homeostatic functions but could also underlie region-specific sensitivities to microglial dysregulation and involvement in age-related neurodegeneration. PMID:26780511

  13. Microglial brain region-dependent diversity and selective regional sensitivities to ageing

    PubMed Central

    Grabert, Kathleen; Michoel, Tom; Karavolos, Michail H; Clohisey, Sara; Baillie, J Kenneth; Stevens, Mark P; Freeman, Tom C; Summers, Kim M; McColl, Barry W

    2015-01-01

    Microglia play critical roles in neural development, homeostasis and neuroinflammation and are increasingly implicated in age-related neurological dysfunction. Neurodegeneration often occurs in disease-specific spatially-restricted patterns, the origins of which are unknown. We performed the first genome-wide analysis of microglia from discrete brain regions across the adult lifespan of the mouse and reveal that microglia have distinct region-dependent transcriptional identities and age in a regionally variable manner. In the young adult brain, differences in bioenergetic and immunoregulatory pathways were the major sources of heterogeneity and suggested that cerebellar and hippocampal microglia exist in a more immune vigilant state. Immune function correlated with regional transcriptional patterns. Augmentation of the distinct cerebellar immunophenotype and a contrasting loss in distinction of the hippocampal phenotype among forebrain regions were key features during ageing. Microglial diversity may enable regionally localised homeostatic functions but could also underlie region-specific sensitivities to microglial dysregulation and involvement in age-related neurodegeneration. PMID:26780511

  14. Theoretical effects of surface diffused region lifetime models on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Dunbar, P. M.; Hauser, J. R.

    1977-01-01

    A computer simulation of silicon solar cells has indicated that the combination of band gap reduction due to heavy doping and certain spatial forms of lifetime dependence can combine to form severe limitations on the open-circuit voltage of such cells. The interaction of these effects tends to shift the active region of the diffused surface layer away from the injecting junction, resulting in an increase in the current density injected into the surface region. Reductions in open circuit voltage as great as 10% over models which do not include these effects can be seen.

  15. Sensitivity encoded silicon photomultiplier--a new sensor for high-resolution PET-MRI.

    PubMed

    Schulz, Volkmar; Berker, Yannick; Berneking, Arne; Omidvari, Negar; Kiessling, Fabian; Gola, Alberto; Piemonte, Claudio

    2013-07-21

    Detectors for simultaneous positron emission tomography and magnetic resonance imaging in particular with sub-mm spatial resolution are commonly composed of scintillator crystal arrays, readout via arrays of solid state sensors, such as avalanche photo diodes (APDs) or silicon photomultipliers (SiPMs). Usually a light guide between the crystals and the sensor is used to enable the identification of crystals which are smaller than the sensor elements. However, this complicates crystal identification at the gaps and edges of the sensor arrays. A solution is to use as many sensors as crystals with a direct coupling, which unfortunately increases the complexity and power consumption of the readout electronics. Since 1997, position-sensitive APDs have been successfully used to identify sub-mm crystals. Unfortunately, these devices show a limitation in their time resolution and a degradation of spatial resolution when placed in higher magnetic fields. To overcome these limitations, this paper presents a new sensor concept that extends conventional SiPMs by adding position information via the spatial encoding of the channel sensitivity. The concept allows a direct coupling of high-resolution crystal arrays to the sensor with a reduced amount of readout channels. The theory of sensitivity encoding is detailed and linked to compressed sensing to compute unique sparse solutions. Two devices have been designed using one- and two-dimensional linear sensitivity encoding with eight and four readout channels, respectively. Flood histograms of both devices show the capability to precisely identify all 4 × 4 LYSO crystals with dimensions of 0.93 × 0.93 × 10 mm(3). For these crystals, the energy and time resolution (MV ± SD) of the devices with one (two)-dimensional encoding have been measured to be 12.3 · (1 ± 0.047)% (13.7 · (1 ± 0.047)%) around 511 keV with a paired coincidence time resolution (full width at half maximum) of 462 · (1 ± 0.054) ps (452 · (1 ± 0

  16. Sensitivity encoded silicon photomultiplier—a new sensor for high-resolution PET-MRI

    NASA Astrophysics Data System (ADS)

    Schulz, Volkmar; Berker, Yannick; Berneking, Arne; Omidvari, Negar; Kiessling, Fabian; Gola, Alberto; Piemonte, Claudio

    2013-07-01

    Detectors for simultaneous positron emission tomography and magnetic resonance imaging in particular with sub-mm spatial resolution are commonly composed of scintillator crystal arrays, readout via arrays of solid state sensors, such as avalanche photo diodes (APDs) or silicon photomultipliers (SiPMs). Usually a light guide between the crystals and the sensor is used to enable the identification of crystals which are smaller than the sensor elements. However, this complicates crystal identification at the gaps and edges of the sensor arrays. A solution is to use as many sensors as crystals with a direct coupling, which unfortunately increases the complexity and power consumption of the readout electronics. Since 1997, position-sensitive APDs have been successfully used to identify sub-mm crystals. Unfortunately, these devices show a limitation in their time resolution and a degradation of spatial resolution when placed in higher magnetic fields. To overcome these limitations, this paper presents a new sensor concept that extends conventional SiPMs by adding position information via the spatial encoding of the channel sensitivity. The concept allows a direct coupling of high-resolution crystal arrays to the sensor with a reduced amount of readout channels. The theory of sensitivity encoding is detailed and linked to compressed sensing to compute unique sparse solutions. Two devices have been designed using one- and two-dimensional linear sensitivity encoding with eight and four readout channels, respectively. Flood histograms of both devices show the capability to precisely identify all 4 × 4 LYSO crystals with dimensions of 0.93 × 0.93 × 10 mm3. For these crystals, the energy and time resolution (MV ± SD) of the devices with one (two)-dimensional encoding have been measured to be 12.3 · (1 ± 0.047)% (13.7 · (1 ± 0.047)%) around 511 keV with a paired coincidence time resolution (full width at half maximum) of 462 · (1 ± 0.054) ps (452 · (1 ± 0

  17. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-04-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50–15000 μmoL L‑1 (cubic SiC NWs) and 5–8000 μmoL L‑1 (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L‑1 respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility.

  18. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

    PubMed Central

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-01-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50–15000 μmoL L−1 (cubic SiC NWs) and 5–8000 μmoL L−1 (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L−1 respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility. PMID:27109361

  19. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively.

    PubMed

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-01-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50-15000 μmoL L(-1) (cubic SiC NWs) and 5-8000 μmoL L(-1) (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L(-1) respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility. PMID:27109361

  20. Network Sensitivity Solutions for Regional Moment Tensor Inversions

    SciTech Connect

    Ford, S R; Dreger, D S; Walter, W R

    2009-06-05

    Well-resolved moment tensor solutions reveal information about the sources of seismic waves. Here we introduce a new way of assessing confidence in the regional full moment tensor inversion via the introduction of the network sensitivity solution (NSS). The NSS takes into account the unique station distribution, frequency band, and signal-to-noise ratio of a given event scenario. The NSS compares both a hypothetical pure source (for example an explosion or an earthquake) and the actual data with several thousand sets of synthetic data from a uniform distribution of all possible sources. The comparison with a hypothetical pure source provides the theoretically best-constrained source-type region for a given set of stations, and with it one can determine whether further analysis with the data is warranted. The NSS that employs the actual data gives a direct comparison of all other source-types with the best-fit source. In this way, one can choose a threshold level of fit where the solution is comfortably constrained. The method is tested for the well-recorded nuclear test, JUNCTION, at the Nevada Test Site. Sources that fit comparably well to a hypothetical pure explosion recorded with no noise at the JUNCTION data stations have a large volumetric component and are not described well by a double-couple (DC) source. The NSS using the real data from JUNCTION is even more tightly constrained to an explosion since the data contains some energy that precludes fitting with any type of deviatoric source. We also calculate the NSS for the October 2006 North Korea test and a nearby earthquake, where the station coverage is poor and the event magnitude is small. The earthquake solution is very well fit by a DC source, and the best-fit solution to the nuclear test (M{sub W}4.1) is dominantly explosion.

  1. A two-axis micromachined silicon actuator with micrometer range electrostatic actuation and picometer sensitive capacitive detection

    NASA Astrophysics Data System (ADS)

    Ayela, F.; Bret, J. L.; Chaussy, J.; Fournier, T.; Ménégaz, E.

    2000-05-01

    This article presents an innovative micromachined silicon actuator. A 50-μm-thick silicon foil is anodically bonded onto a broached Pyrex substrate. A free standing membrane and four coplanar electrodes in close proximity are then lithographied and etched. The use of phosphorus doped silicon with low electrical resistivity allows the application of an electrostatic force between one electrode and the moving diaphragm. This plane displacement and the induced interelectrode variation are capacitively detected. Due to the very low electrical resistivity of the doped silicon, there is no need to metallize the vertical trenches of the device. No piezoelectric transducer takes place so that the mechanical device is free from any hysteretic or temperature dependance. The range of the possible actuation along the x and y axis is around 5 μm. The actual sensitivity is xn=0.54 Å/Hz1/2 and yn=0.14 Å/Hz1/2. The microengineering steps and the electronic setup devoted to design the actuator and to perform relative capacitive measurements ΔC/C=10-6 from an initial value C≈10-13 F are described. The elaborated tests and performances of the device are presented. As a conclusion, some experimental projects using this subnanometric sensitive device are mentioned.

  2. Direct detection of transcription factors in cotyledons during seedling development using sensitive silicon-substrate photonic crystal protein arrays.

    PubMed

    Jones, Sarah I; Tan, Yafang; Shamimuzzaman, Md; George, Sherine; Cunningham, Brian T; Vodkin, Lila

    2015-03-01

    Transcription factors control important gene networks, altering the expression of a wide variety of genes, including those of agronomic importance, despite often being expressed at low levels. Detecting transcription factor proteins is difficult, because current high-throughput methods may not be sensitive enough. One-dimensional, silicon-substrate photonic crystal (PC) arrays provide an alternative substrate for printing multiplexed protein microarrays that have greater sensitivity through an increased signal-to-noise ratio of the fluorescent signal compared with performing the same assay upon a traditional aminosilanized glass surface. As a model system to test proof of concept of the silicon-substrate PC arrays to directly detect rare proteins in crude plant extracts, we selected representatives of four different transcription factor families (zinc finger GATA, basic helix-loop-helix, BTF3/NAC [for basic transcription factor of the NAC family], and YABBY) that have increasing transcript levels during the stages of seedling cotyledon development. Antibodies to synthetic peptides representing the transcription factors were printed on both glass slides and silicon-substrate PC slides along with antibodies to abundant cotyledon proteins, seed lectin, and Kunitz trypsin inhibitor. The silicon-substrate PC arrays proved more sensitive than those performed on glass slides, detecting rare proteins that were below background on the glass slides. The zinc finger transcription factor was detected on the PC arrays in crude extracts of all stages of the seedling cotyledons, whereas YABBY seemed to be at the lower limit of their sensitivity. Interestingly, the basic helix-loop-helix and NAC proteins showed developmental profiles consistent with their transcript patterns, indicating proof of concept for detecting these low-abundance proteins in crude extracts. PMID:25635113

  3. Development of a high-sensitivity immunoassay for amyloid-beta 1-42 using a silicon microarray platform.

    PubMed

    Gagni, Paola; Sola, Laura; Cretich, Marina; Chiari, Marcella

    2013-09-15

    In this work, we present a highly sensitive immunoassay for the detection of the Alzheimer's disease (AD) biomarker amyloid-beta 1-42 (Aβ42) based on a label/label-free microarray platform that utilises silicon/silicon oxide (Si/SiO2) substrates. Due to constructive interference, Si/SiO2 layered slides allow enhancement of the fluorescence intensity on the surface with significant improvements in sensitivity of detection. The same substrate allows the label-free multiplexed detection of targets using the Interferometric Reflectance Imaging Sensor (IRIS), a platform amenable to high-throughput detection of mass changes on microarray substrates. Silicon chips are coated with copoly(DMA-NAS-MAPS), a ter-copolymer made from dimethylacrylamide (DMA), 3-(trimethoxysilyl)propyl methacrylate (MAPS) and N-Acryloyloxy succinimide (NAS). Aβ42 aggregation was studied by circular dichroism (CD), and an optimal antibody pair was selected based on specificity of recognition, binding yield and spot morphology of the capture antibody on the coated silicon surface as analysed by IRIS. Finally, incubation conditions were optimised, and an unprecedented Aβ42 detection sensitivity of 73pg/mL was achieved using an artificial cerebrospinal fluid (CSF) sample. Because of their multiplexing capability, low volume sample consumption and efficient sample-to-result time for population-wide screening, microarrays are ideal tools for the identification of individuals with preclinical AD who are still cognitively healthy. The high sensitivity of this assay format, potentially coupled to a pre-concentration step or signal-enhancing modifications, could lead to a non-invasive, inexpensive diagnostic tool for population-wide screening of AD biomarkers in biological fluids other than CSF, such as serum or plasma. PMID:23624018

  4. Optical and photoelectric- and gas-sensitive properties of porous silicon

    NASA Astrophysics Data System (ADS)

    Smyntyna, Valentin A.; Vashpanov, Yurij A.

    1998-04-01

    The photoelectronic properties of samples of porous silicon received by method of anodic electrochemical etching of monocrystalline silicon in electrolytes on the base of hydrofluoric acid are investigated. Wide spectral photosensitivity from infra-red to ultraviolet of spectrum area on series of received structures is found out. The physical mechanism of photosensitivity is discussed. The electronic parameters of porous silicon samples under gas adsorption were investigated. It was opend that the ammonia adsorption changes electrical conductivity of porous silicon samples on constant and variable current of measurement. In microporous asymmetrical structures we observed electromotive force on contacts under ammonia adsorption. The physical mechanism of adsorption of ammonia is connected with interaction dipolar molecules ammonia with double electric layer on surface of porous silicon.

  5. Angular sensitivity of modeled scientific silicon charge-coupled devices to initial electron direction

    NASA Astrophysics Data System (ADS)

    Plimley, Brian; Coffer, Amy; Zhang, Yigong; Vetter, Kai

    2016-08-01

    Previously, scientific silicon charge-coupled devices (CCDs) with 10.5-μm pixel pitch and a thick (650 μm), fully depleted bulk have been used to measure gamma-ray-induced fast electrons and demonstrate electron track Compton imaging. A model of the response of this CCD was also developed and benchmarked to experiment using Monte Carlo electron tracks. We now examine the trade-off in pixel pitch and electronic noise. We extend our CCD response model to different pixel pitch and readout noise per pixel, including pixel pitch of 2.5 μm, 5 μm, 10.5 μm, 20 μm, and 40 μm, and readout noise from 0 eV/pixel to 2 keV/pixel for 10.5 μm pixel pitch. The CCD images generated by this model using simulated electron tracks are processed by our trajectory reconstruction algorithm. The performance of the reconstruction algorithm defines the expected angular sensitivity as a function of electron energy, CCD pixel pitch, and readout noise per pixel. Results show that our existing pixel pitch of 10.5 μm is near optimal for our approach, because smaller pixels add little new information but are subject to greater statistical noise. In addition, we measured the readout noise per pixel for two different device temperatures in order to estimate the effect of temperature on the reconstruction algorithm performance, although the readout is not optimized for higher temperatures. The noise in our device at 240 K increases the FWHM of angular measurement error by no more than a factor of 2, from 26° to 49° FWHM for electrons between 425 keV and 480 keV. Therefore, a CCD could be used for electron-track-based imaging in a Peltier-cooled device.

  6. Formation, characterization, and flow dynamics of nanostructure modified sensitive and selective gas sensors based on porous silicon

    NASA Astrophysics Data System (ADS)

    Ozdemir, Serdar

    Nanopore covered microporous silicon interfaces have been formed via an electrochemical etch for gas sensor applications. Rapid reversible and sensitive gas sensors have been fabricated. Both top-down and bottom-up approaches are utilized in the process. A nano-pore coated micro-porous silicon surface is modified selectively for sub-ppm detection of NH3, PH3 , NO, H2S, SO2. The selective depositions include electrolessly generated SnO2, CuxO, Au xO, NiO, and nanoparticles such as TiO2, MgO doped TiO 2, Al2O3, and ZrO2. Flow dynamics are analyzed via numerical simulations and response data. An array of sensors is formed to analyze mixed gas response. A general coating selection method for chemical sensors is established via an extrapolation on the inverse of the Hard-Soft Acid-Base concept. In Chapter 1, the current state of the porous silicon gas sensor research is reviewed. Since metal oxide thin films, and, recently, nanowires are dominantly used for sensing application, the general properties of metal oxides are also discussed in this chapter. This chapter is concluded with a discussion about commercial gas sensors and the advantages of using porous silicon as a sensing material. The PS review discussed at the beginning of this chapter is an overview of the following publication: (1) "The Potential of Porous Silicon Gas Sensors", Serdar Ozdemir, James L. Gole, Current Opinion in Solid State and Materials Science, 11, 92-100 (2007). In Chapter 2, porous silicon formation is explained in detail. Interesting results of various silicon anodization experiments are discussed. In the second part of this chapter, the microfabrication process of porous silicon conductometric gas sensors and gas testing set up are briefly introduced. In chapter 3, metal oxide nanoparticle/nanocluster formation and characterization experiments via SEM and XPS analysis are discussed. Chapter 4 is an overview of the test results for various concentrations NH3, NO, NO2 and PH3. The

  7. Tuning Light Emission of a Pressure-Sensitive Silicon/ZnO Nanowires Heterostructure Matrix through Piezo-phototronic Effects.

    PubMed

    Chen, Mengxiao; Pan, Caofeng; Zhang, Taiping; Li, Xiaoyi; Liang, Renrong; Wang, Zhong Lin

    2016-06-28

    Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect. PMID:27276167

  8. The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells.

    NASA Technical Reports Server (NTRS)

    Ghosh, S.; Sargent, G. A.

    1972-01-01

    Study regions of lattice disorder produced in lithium-doped float-zone melted n/p-type silicon solar cells by irradiation with monoenergetic neutrons at doses between 10 to the 10th and 10 to the 13th per cu cm. The defect regions were revealed by chemically etching the surface of the solar cells and by observing carbon replicas in an electron microscope. It was found that the defect density increased with increasing irradiation dose and increased lithium content, whereas the average defect diameter was found to decrease. From thermal annealing experiments it was found that in the lithium-doped material the defect structure was stable at temperatures between 300 and 1200 K. This was found to be in contrast to the undoped material where at the lowest doses considerable annealing was observed to occur. These results are discussed in terms of the theoretical predictions and models of defect clusters proposed by Gossick (1959) and Crawford and Cleland (1959).

  9. Enhancement of Capture Sensitivity for Circulating Tumor Cells in a Breast Cancer Patient's Blood by Silicon Nanowire Platform.

    PubMed

    Kim, Dong-Joo; Choi, Mun-Ki; Jeong, Jin-Tak; Lim, Jung-Taek; Lee, Han-Byoel; Han, Wonshik; Lee, Sang-Kwon

    2016-04-01

    The separation of circulating tumor cells (CTCs) from the blood of cancer patients with high sensitivity is an essential technique for selecting chemotherapeutic agents at a patient-by-patient level. Recently, various research groups have reported a nanostructure-based platform for rare cell capture due to its high surface area and 3D nanotopographic features. However, evaluation of capture sensitivity based on chemical modification of the nanostructure surface has not yet been performed. Here, we evaluated the capture sensitivity for CTCs from the blood of three patients diagnosed with stage IV metastatic breast cancer by using the following three platforms: streptavidin-conjugated silicon nanowire (STR-SiNW), poly-l-lysine-coated silicon nanowire (PLL-SiNW), and poly-l-lysine-coated glass (PLL-glass). The number of evaluated CTCs on STR-SiNW, PLL-SiNW, and PLL-glass were 16.2 ± 5.5 cells, 7.3 ± 2.9 cells, and 4.7 ± 1.5 cells, respectively, per 0.5 ml. Therefore, we suggest that the STR-SiNW platform is highly adaptable for the quantitative evaluation of CTCs from the blood of cancer patients in the clinical setting. PMID:27301191

  10. Enhancing the far-ultraviolet sensitivity of silicon complementary metal oxide semiconductor imaging arrays

    NASA Astrophysics Data System (ADS)

    Retherford, Kurt D.; Bai, Yibin; Ryu, Kevin K.; Gregory, James A.; Welander, Paul B.; Davis, Michael W.; Greathouse, Thomas K.; Winters, Gregory S.; Suntharalingam, Vyshnavi; Beletic, James W.

    2015-10-01

    We report our progress toward optimizing backside-illuminated silicon P-type intrinsic N-type complementary metal oxide semiconductor devices developed by Teledyne Imaging Sensors (TIS) for far-ultraviolet (UV) planetary science applications. This project was motivated by initial measurements at Southwest Research Institute of the far-UV responsivity of backside-illuminated silicon PIN photodiode test structures, which revealed a promising QE in the 100 to 200 nm range. Our effort to advance the capabilities of thinned silicon wafers capitalizes on recent innovations in molecular beam epitaxy (MBE) doping processes. Key achievements to date include the following: (1) representative silicon test wafers were fabricated by TIS, and set up for MBE processing at MIT Lincoln Laboratory; (2) preliminary far-UV detector QE simulation runs were completed to aid MBE layer design; (3) detector fabrication was completed through the pre-MBE step; and (4) initial testing of the MBE doping process was performed on monitoring wafers, with detailed quality assessments.

  11. Sputtering of silicon and its compounds in the electronic stopping region

    NASA Technical Reports Server (NTRS)

    Qiu, Y.; Griffith, J. E.; Meng, W. J.; Tombrello, T. A.

    1983-01-01

    Silicon, silicon dioxide, and silicon nitride have been sputtered with chlorine ions at 5 MeV and 20 MeV. While the yield from the silicon target was unmeasurably low, the insulating compounds exhibited the enhanced yields observed in other insulating targets. The yield follows the electronic stopping power and seems to be independent of the target's thermal properties. Some of the data suggest that the enhanced sputtering mechanism may be active in extremely thin films (not less than 3 monolayers).

  12. Nanoscale thickness double-gated field effect silicon sensors for sensitive pH detection in fluid

    SciTech Connect

    Elibol, Oguz H.; Reddy, Bobby Jr.; Bashir, Rashid

    2008-05-12

    In this work, we report on the optimization of a double-gate silicon-on-insulator field effect device operation to maximize pH sensitivity. The operating point can be fine tuned by independently biasing the fluid and the back gate of the device. Choosing the bias points such that device is nearly depleted results in an exponential current response--in our case, 0.70 decade per unit change in pH. This value is comparable to results obtained with devices that have been further scaled in width, reported at the forefront of the field, and close to the ideal value of 1 decade/pH. By using a thin active area, sensitivity is increased due to increased coupling between the two conducting surfaces of the devices.

  13. Ultra-sensitive nucleic acids detection with electrical nanosensors based on CMOS-compatible silicon nanowire field-effect transistors.

    PubMed

    Lu, Na; Gao, Anran; Dai, Pengfei; Li, Tie; Wang, Yi; Gao, Xiuli; Song, Shiping; Fan, Chunhai; Wang, Yuelin

    2013-10-01

    Silicon nanowire field-effect transistors (SiNW-FETs) have recently emerged as a type of powerful nanoelectronic biosensors due to their ultrahigh sensitivity, selectivity, label-free and real-time detection capabilities. Here, we present a protocol as well as guidelines for detecting DNA with complementary metal oxide semiconductor (CMOS) compatible SiNW-FET sensors. SiNWs with high surface-to-volume ratio and controllable sizes were fabricated with an anisotropic self-stop etching technique. Probe DNA molecules specific for the target DNA were covalently modified onto the surface of the SiNWs. The SiNW-FET nanosensors exhibited an ultrahigh sensitivity for detecting the target DNA as low as 1 fM and good selectivity for discrimination from one-base mismatched DNA. PMID:23886908

  14. High-sensitivity pesticide detection via silicon nanowires-supported acetylcholinesterase-based electrochemical sensors

    NASA Astrophysics Data System (ADS)

    Su, Shao; He, Yao; Zhang, Mingliang; Yang, Kun; Song, Shiping; Zhang, Xiaohong; Fan, Chunhai; Lee, Shuit-Tong

    2008-07-01

    We report the use of a silicon-based nanocomplex, i.e., gold nanoparticles-coated silicon nanowires, for the improvement of acetylcholinesterase (AChE)-based electrochemical sensors for pesticide detection. Owing to the high electrical conductivity of the nanocomplex and its compatibility with the enzyme, the sensor exhibited significantly enhanced performance. The AChE enzyme bound to the surface possessed Michaelis-Menton constant of 81μM, resembling that in its free form. The sensor showed rapid response toward substrate acetylcholine in the concentration range of 1.0μM-1.0mM. This AChE nanosensor could detect as low as 8ng/L dichlorvos, an organophosphate pesticide.

  15. Improvement of sensitivity in continuous wave near infra-red spectroscopy systems by using silicon photomultipliers

    PubMed Central

    Pagano, Roberto; Libertino, Sebania; Sanfilippo, Delfo; Fallica, Giorgio; Lombardo, Salvatore

    2016-01-01

    We experimentally analyze the signal-to-noise ratio of continuous wave (CW) near infrared spectroscopy (NIRS) reflectance systems based on light emitting diodes and silicon photomultipliers for high performance low cost NIRS biomedical systems. We show that under suitable experimental conditions such systems exhibit a high SNR, which allows an SDS of 7 cm, to our knowledge the largest ever demonstrated in a CW-NIRs system. PMID:27486551

  16. Grafting of thermo-sensitive N-vinylcaprolactam onto silicone rubber through the direct radiation method

    NASA Astrophysics Data System (ADS)

    Valencia-Mora, Ricardo A.; Zavala-Lagunes, Edgar; Bucio, Emilio

    2016-07-01

    The modification of silicone rubber films (SR) was performed by radiation-induced graft polymerization of thermosensitive poly(N-vinylcaprolactam) (PNVCL) using gamma rays from a Co-60 source. The graft polymerization was obtained by a direct radiation method with doses from 5 to 70 kGy, at monomer concentrations between 5% and 70% in toluene. Grafting was confirmed by infrared, differential scanning calorimetry, thermogravimetric analysis, and swelling studies. The lower critical solution temperature (LCST) of the grafted SR was measured by swelling and differential scanning calorimetry.

  17. Facile synthesis of silicon carbide-titanium dioxide semiconducting nanocomposite using pulsed laser ablation technique and its performance in photovoltaic dye sensitized solar cell and photocatalytic water purification

    NASA Astrophysics Data System (ADS)

    Gondal, M. A.; Ilyas, A. M.; Baig, Umair

    2016-08-01

    Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO2) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet-visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

  18. Reduction of phase noise to amplitude noise conversion in silicon waveguide-based phase-sensitive amplification.

    PubMed

    Ma, Yonghua; Liu, Hongjun; Sun, Qibing; Huang, Nan; Wang, Zhaolu

    2016-04-20

    We use a vector phase sensitive amplification (PSA) scheme, which can eliminate the inherent phase noise (PN) to amplitude noise (AN) conversion in a conventional PSA process. A dispersion-engineered silicon strip waveguide is used to investigate the vector PSA scheme at the telecom wavelengths. The phase-dependent gain and phase-to-phase transfer functions as well as constellation diagram at different signal polarization states (SPSs) are numerically analyzed. It is found that the PN to AN conversion is completely suppressed when the SPS is identical to one of the pump polarization states. Moreover, the binary phase shift keying signal is regenerated by the proposed vector PSA scheme, and the error vector magnitude is calculated to assess the regeneration capacity. Our results have potential application in all-optical signal processing. PMID:27140079

  19. High Sensitivity pH Sensor Based on Porous Silicon (PSi) Extended Gate Field-Effect Transistor.

    PubMed

    Al-Hardan, Naif H; Abdul Hamid, Muhammad Azmi; Ahmed, Naser M; Jalar, Azman; Shamsudin, Roslinda; Othman, Norinsan Kamil; Kar Keng, Lim; Chiu, Weesiong; Al-Rawi, Hamzah N

    2016-01-01

    In this study, porous silicon (PSi) was prepared and tested as an extended gate field-effect transistor (EGFET) for pH sensing. The prepared PSi has pore sizes in the range of 500 to 750 nm with a depth of approximately 42 µm. The results of testing PSi for hydrogen ion sensing in different pH buffer solutions reveal that the PSi has a sensitivity value of 66 mV/pH that is considered a super Nernstian value. The sensor considers stability to be in the pH range of 2 to 12. The hysteresis values of the prepared PSi sensor were approximately 8.2 and 10.5 mV in the low and high pH loop, respectively. The result of this study reveals a promising application of PSi in the field for detecting hydrogen ions in different solutions. PMID:27338381

  20. Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide-semiconductor-compatible silicon nanowires

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Jun; Agarwal, Ajay; Buddharaju, Kavitha D.; Singh, Navab; Gao, Zhiqiang

    2007-06-01

    Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide- semiconductor-compatible silicon nanowires (SiNWs) with crown ethers covalently immobilized on their surface are presented. A densely packed organic monolayer terminated with amine groups is introduced to the SiNW surface via hydrosilylation. Amine-modified crown ethers, acting as sensing elements, are then immobilized onto the SiNWs through a cross-linking reaction with the monolayer. The crown ether-functionalized SiNWs recognize Na+ and K+ according to their complexation ability to the crown ethers. The SiNW sensors are highly selective and capable of achieving an ultralow detection limit down to 50nM, over three orders of magnitude lower than that of conventional crown ether-based ion-selective electrodes.

  1. High Sensitivity pH Sensor Based on Porous Silicon (PSi) Extended Gate Field-Effect Transistor

    PubMed Central

    Al-Hardan, Naif H.; Abdul Hamid, Muhammad Azmi; Ahmed, Naser M.; Jalar, Azman; Shamsudin, Roslinda; Othman, Norinsan Kamil; Kar Keng, Lim; Chiu, Weesiong; Al-Rawi, Hamzah N.

    2016-01-01

    In this study, porous silicon (PSi) was prepared and tested as an extended gate field-effect transistor (EGFET) for pH sensing. The prepared PSi has pore sizes in the range of 500 to 750 nm with a depth of approximately 42 µm. The results of testing PSi for hydrogen ion sensing in different pH buffer solutions reveal that the PSi has a sensitivity value of 66 mV/pH that is considered a super Nernstian value. The sensor considers stability to be in the pH range of 2 to 12. The hysteresis values of the prepared PSi sensor were approximately 8.2 and 10.5 mV in the low and high pH loop, respectively. The result of this study reveals a promising application of PSi in the field for detecting hydrogen ions in different solutions. PMID:27338381

  2. Front-end circuit for position sensitive silicon and vacuum tube photomultipliers with gain control and depth of interaction measurement

    NASA Astrophysics Data System (ADS)

    Herrero, Vicente; Colom, Ricardo; Gadea, Rafael; Lerche, Christoph W.; Cerdá, Joaquín; Sebastiá, Ángel; Benlloch, José M.

    2007-06-01

    Silicon Photomultipliers, though still under development for mass production, may be an alternative to traditional Vacuum Photomultipliers Tubes (VPMT). As a consequence, electronic front-ends initially designed for VPMT will need to be modified. In this simulation, an improved architecture is presented which is able to obtain impact position and depth of interaction of a gamma ray within a continuous scintillation crystal, using either kind of PM. A current sensitive preamplifier stage with individual gain adjustment interfaces the multi-anode PM outputs with a current division resistor network. The preamplifier stage allows to improve front-end processing delay and temporal resolution behavior as well as to increase impact position calculation resolution. Depth of interaction (DOI) is calculated from the width of the scintillation light distribution, which is related to the sum of voltages in resistor network input nodes. This operation is done by means of a high-speed current mode scheme.

  3. Mediator-less highly sensitive voltammetric detection of glutamate using glutamate dehydrogenase/vertically aligned CNTs grown on silicon substrate.

    PubMed

    Gholizadeh, Azam; Shahrokhian, Saeed; zad, Azam Iraji; Mohajerzadeh, Shamsoddin; Vosoughi, Manouchehr; Darbari, Sara; Sanaee, Zeinab

    2012-01-15

    A sensitive glutamate biosensor is prepared based on glutamate dehydrogenase/vertically aligned carbon nanotubes (GLDH, VACNTs). Vertically aligned carbon nanotubes were grown on a silicon substrate by direct current plasma enhanced chemical vapor deposition (DC-PECVD) method. The electrochemical behavior of the synthesized VACNTs was investigated by cyclic voltammetry and electrochemical impedance spectroscopic methods. Glutamate dehydrogenase covalently attached on tip of VACNTs. The electrochemical performance of the electrode for detection of glutamate was investigated by cyclic and differential pulse voltammetry. Differential pulse voltammetric determinations of glutamate are performed in mediator-less condition and also, in the presence of 1 and 5 μM thionine as electron mediator. The linear calibration curve of the concentration of glutamate versus peak current is investigated in a wide range of 0.1-500 μM. The mediator-less biosensor has a low detection limit of 57 nM and two linear ranges of 0.1-20 μM with a sensitivity of 0.976 mA mM(-1) cm(-2) and 20-300 μM with a sensitivity of 0.182 mA mM(-1) cm(-2). In the presence of 1 μM thionine as an electron mediator, the prepared biosensor shows a low detection limit of 68 nM and two linear ranges of 0.1-20 with a calibration sensitivity of 1.17 mA mM(-1) cm(-2) and 20-500 μM with a sensitivity of 0.153 mA mM(-1) cm(-2). The effects of the other biological compounds on the voltammetric behavior of the prepared biosensor and its response stability are investigated. The results are demonstrated that the GLDH/VACNTs electrode even without electron mediator is a suitable basic electrode for detection of glutamate. PMID:22040749

  4. A silicon nanowire-based electrochemical glucose biosensor with high electrocatalytic activity and sensitivity

    NASA Astrophysics Data System (ADS)

    Su, Shao; He, Yao; Song, Shiping; Li, Di; Wang, Lihua; Fan, Chunhai; Lee, Shuit-Tong

    2010-09-01

    An electrochemical glucose biosensor was developed by immobilizing glucose oxidase (GOx) on an electrode decorated with a novel nanostructure, silicon nanowires (SiNWs) with in situ grown gold nanoparticles (AuNPs). The immobilized GOx displayed a pair of well-defined and quasi-reversible redox peaks with a formal potential (E°') of -0.376 V in a phosphate buffer solution. The fabricated glucose biosensor has good electrocatalytic activity toward oxidation of glucose. In addition, such resultant SiNWs-based glucose biosensor possesses high biological affinity. Particularly, the apparent Michaelis-Mentan constant was estimated to be 0.902 mM, which is much smaller than the reported values for GOx at a range of nanomaterials-incorporated electrodes. Consequently, this novel SiNWs-based biosensor is expected to be a promising tool for biological assays (e.g., monitoring blood glucose).

  5. Electronic transitions of single silicon vacancy centers in the near-infrared spectral region

    NASA Astrophysics Data System (ADS)

    Neu, Elke; Albrecht, Roland; Fischer, Martin; Gsell, Stefan; Schreck, Matthias; Becher, Christoph

    2012-06-01

    Photoluminescence (PL) spectra of single silicon vacancy (SiV) centers in diamond frequently feature very narrow room temperature PL lines in the near-infrared (NIR) spectral region, mostly between 820 nm and 840 nm, in addition to the well known zero-phonon line (ZPL) at approximately 738 nm [E. Neu , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.84.205211 84, 205211 (2011)]. We here exemplarily prove for a single SiV center that this NIR PL is due to an additional purely electronic transition (ZPL). For the NIR line at 822.7 nm, we find a room temperature linewidth of 1.4 nm (2.6 meV). The line saturates at similar excitation power as the ZPL. The ZPL and NIR line exhibit identical polarization properties. Cross-correlation measurements between the ZPL and the NIR line reveal anticorrelated emission and prove that the lines originate from a single SiV center, furthermore indicating a fast switching between the transitions (0.7 ns). g(2) autocorrelation measurements exclude that the NIR line is a vibronic sideband or that it arises due to a transition from/to a metastable (shelving) state.

  6. SENSITIVITY OF A REGIONAL OXIDANT MODEL TO VARIATIONS IN CLIMATE PARAMETERS, VOLUME I AND II

    EPA Science Inventory

    In order to investigate the sensitivity of ozone concentrations to future climate variations, a regional oxidant model was applied for future climate scenarios to two regions: one covering central California (San Joaquin Valley, Sierra Nevada mountains and the San Francisco Bay A...

  7. Improvement in pH sensitivity of low-temperature polycrystalline-silicon thin-film transistor sensors using H2 sintering.

    PubMed

    Yen, Li-Chen; Tang, Ming-Tsyr; Chang, Fang-Yu; Pan, Tung-Ming; Chao, Tien-Sheng; Lee, Chiang-Hsuan

    2014-01-01

    In this article, we report an improvement in the pH sensitivity of low-temperature polycrystalline-silicon (poly-Si) thin-film transistor (TFT) sensors using an H2 sintering process. The low-temperature polycrystalline-silicon (LTPS) TFT sensor with H2 sintering exhibited a high sensitivity than that without H2 sintering. This result may be due to the resulting increase in the number of Si-OH2(+) and Si-O(-) bonds due to the incorporation of H in the gate oxide to reduce the dangling silicon bonds and hence create the surface active sites and the resulting increase in the number of chemical reactions at these surface active sites. Moreover, the LTPS TFT sensor device not only offers low cost and a simple fabrication processes, but the technique also can be extended to integrate the sensor into other systems. PMID:24573308

  8. Improvement in pH Sensitivity of Low-Temperature Polycrystalline-Silicon Thin-Film Transistor Sensors Using H2 Sintering

    PubMed Central

    Yen, Li-Chen; Tang, Ming-Tsyr; Chang, Fang-Yu; Pan, Tung-Ming; Chao, Tien-Sheng; Lee, Chiang-Hsuan

    2014-01-01

    In this article, we report an improvement in the pH sensitivity of low-temperature polycrystalline-silicon (poly-Si) thin-film transistor (TFT) sensors using an H2 sintering process. The low-temperature polycrystalline-silicon (LTPS) TFT sensor with H2 sintering exhibited a high sensitivity than that without H2 sintering. This result may be due to the resulting increase in the number of Si–OH2+ and Si–O− bonds due to the incorporation of H in the gate oxide to reduce the dangling silicon bonds and hence create the surface active sites and the resulting increase in the number of chemical reactions at these surface active sites. Moreover, the LTPS TFT sensor device not only offers low cost and a simple fabrication processes, but the technique also can be extended to integrate the sensor into other systems. PMID:24573308

  9. Sensitive Detection of Protein and miRNA Cancer Biomarkers using Silicon-Based Photonic Crystals and A Resonance Coupling Laser Scanning Platform

    PubMed Central

    George, Sherine; Chaudhery, Vikram; Lu, Meng; Takagi, Miki; Amro, Nabil; Pokhriyal, Anusha; Tan, Yafang; Ferreira, Placid; Cunningham, Brian T.

    2013-01-01

    Enhancement of the fluorescent output of surface-based fluorescence assays by performing them upon nanostructured photonic crystal (PC) surfaces has been demonstrated to increase signal intensities by >8000×. Using the multiplicative effects of optical resonant coupling to the PC in increasing the electric field intensity experienced by fluorescent labels (“enhanced excitation”) and the spatially biased funneling of fluorophore emissions through coupling to PC resonances (“enhanced extraction”), PC enhanced fluorescence (PCEF) can be adapted to reduce the limits of detection of disease biomarker assays, and to reduce the size and cost of high sensitivity detection instrumentation. In this work, we demonstrate the first silicon-based PCEF detection platform for multiplexed biomarker assay. The sensor in this platform is a silicon-based PC structure, comprised of a SiO2 grating that is overcoated with a thin film of high refractive index TiO2 and is produced in a semiconductor foundry for low cost, uniform, and reproducible manufacturing. The compact detection instrument that completes this platform was designed to efficiently couples fluorescence excitation from a semiconductor laser to the resonant optical modes of the PC, resulting in elevated electric field strength that is highly concentrated within the region <100 nm from the PC surface. This instrument utilizes a cylindrically focused line to scan a microarray in <1 minute. To demonstrate the capabilities of this sensor-detector platform, microspot fluorescent sandwich immunoassays using secondary antibodies labeled with Cy5 for two cancer biomarkers (TNF-α and IL-3) were performed. Biomarkers were detected at concentrations as low as 0.1 pM. In a fluorescent microarray for detection of a breast cancer miRNA biomarker miR-21, the miRNA was detectable at a concentration of 0.6 pM. PMID:23963502

  10. Sensitized phenotypic screening identifies gene dosage sensitive region on chromosome 11 that predisposes to disease in mice

    PubMed Central

    Ermakova, Olga; Piszczek, Lukasz; Luciani, Luisa; Cavalli, Florence M G; Ferreira, Tiago; Farley, Dominika; Rizzo, Stefania; Paolicelli, Rosa Chiara; Al-Banchaabouchi, Mumna; Nerlov, Claus; Moriggl, Richard; Luscombe, Nicholas M; Gross, Cornelius

    2011-01-01

    The identification of susceptibility genes for human disease is a major goal of current biomedical research. Both sequence and structural variation have emerged as major genetic sources of phenotypic variability and growing evidence points to copy number variation as a particularly important source of susceptibility for disease. Here we propose and validate a strategy to identify genes in which changes in dosage alter susceptibility to disease-relevant phenotypes in the mouse. Our approach relies on sensitized phenotypic screening of megabase-sized chromosomal deletion and deficiency lines carrying altered copy numbers of ∼30 linked genes. This approach offers several advantages as a method to systematically identify genes involved in disease susceptibility. To examine the feasibility of such a screen, we performed sensitized phenotyping in five therapeutic areas (metabolic syndrome, immune dysfunction, atherosclerosis, cancer and behaviour) of a 0.8 Mb reciprocal chromosomal duplication and deficiency on chromosome 11 containing 27 genes. Gene dosage in the region significantly affected risk for high-fat diet-induced metabolic syndrome, antigen-induced immune hypersensitivity, ApoE-induced atherosclerosis, and home cage activity. Follow up studies on individual gene knockouts for two candidates in the region showed that copy number variation in Stat5 was responsible for the phenotypic variation in antigen-induced immune hypersensitivity and metabolic syndrome. These data demonstrate the power of sensitized phenotypic screening of segmental aneuploidy lines to identify disease susceptibility genes. PMID:21204268

  11. A self-powered sensitive ultraviolet photodetector based on epitaxial graphene on silicon carbide

    NASA Astrophysics Data System (ADS)

    Jiao, Huang; Li-Wei, Guo; Wei, Lu; Yong-Hui, Zhang; Zhe, Shi; Yu-Ping, Jia; Zhi-Lin, Li; Jun-Wei, Yang; Hong-Xiang, Chen; Zeng-Xia, Mei; Xiao-Long, Chen

    2016-06-01

    A self-powered graphene-based photodetector with high performance is particularly useful for device miniaturization and to save energy. Here, we report a graphene/silicon carbide (SiC)-based self-powered ultraviolet photodetector that exhibits a current responsivity of 7.4 mA/W with a response frequency of over a megahertz under 325-nm laser irradiation. The built-in photovoltage of the photodetector is about four orders of magnitude higher than previously reported results for similar devices. These favorable properties are ascribed to the ingenious device design using the combined advantages of graphene and SiC, two terminal electrodes, and asymmetric light irradiation on one of the electrodes. Importantly, the photon energy is larger than the band gap of SiC. This self-powered photodetector is compatible with modern semiconductor technology and shows potential for applications in ultraviolet imaging and graphene-based integrated circuits. Project supported by the National Key Basic Research Program of China (Grant Nos. 2011CB932700 and 2013CBA01603) and the National Natural Science Foundation of China (Grant Nos. 51472265 and 51272279).

  12. Sensitized broadband near-infrared luminescence from bismuth-doped silicon-rich silica films.

    PubMed

    Miwa, Yuji; Sun, Hong-Tao; Imakita, Kenji; Fujii, Minoru; Teng, Yu; Qiu, Jianrong; Sakka, Yoshio; Hayashi, Shinji

    2011-11-01

    Developing Si compatible optical sources has attracted a great deal of attention owing to the potential for forming inexpensive, monolithic Si-based integrated devices. In this Letter, we show that ultra broadband near-IR (NIR) luminescence in the optical telecommunication window of silica optical fibers was obtained for Bi-doped silicon-rich silica films prepared by a co-sputtering method. Without excess Si, i.e., Bi-doped pure silica films, no luminescence was observed in the NIR range. A broad Bi-related NIR photoluminescence appears when excess Si was doped in the Bi-doped silica. The luminescence properties depended strongly on the amount of excess Si and the annealing temperature. Photoluminescence results suggest that excess Si acts as an agent to activate Bi NIR luminescence centers and also as an energy donor to transfer excitation energy to the centers. It is believed that this peculiar structure might find some important applications in Si photonics. PMID:22048371

  13. Comments on "Sensitive analysis of carbon, chromium and silicon in steel using picosecond laser induced low pressure helium plasma"

    NASA Astrophysics Data System (ADS)

    Zaytsev, Sergey M.; Popov, Andrey M.; Zorov, Nikita B.; Labutin, Timur A.

    2016-04-01

    In the paper "Sensitive analysis of carbon, chromium and silicon in steel using picosecond laser induced low pressure helium plasma" by Syahrun Nur Abdulmadjid, Nasrullah Idris, Marincan Pardede, Eric Jobiliong, Rinda Hedwig, Zener Sukra Lie, Hery Suyanto, May On Tjia, Koo Hendrik Kurniawan and Kiichiro Kagawa [Spectrochim. Acta Part B 114 (2015) 1-6], the authors presented experimental study to demonstrate the sensitive detection of C, Cr and Si in low-alloy steels under low pressure He atmosphere. Although the use of only UV-VIS spectral range for determination of these elements seems to be a beneficial, the point that needs to be commented is the result of carbon determination with the use of C I 247.856 nm line. Thermodynamic modeling based on the NIST and R. Kurucz data for the different excitation conditions in plasma demonstrates that it is hardly possible to distinguish any carbon signal due to significantly intensive iron line Fe II 247.857 nm. Authors are kindly requested to re-consider this part of their study.

  14. Variations in the sensitivity of US maize yield to extreme temperatures by region and growth phase

    NASA Astrophysics Data System (ADS)

    Butler, Ethan E.; Huybers, Peter

    2015-03-01

    Maize yield is sensitive to high temperatures, and most large scale analyses have used a single, fixed sensitivity to represent this vulnerability over the course of a growing season. Field scale studies, in contrast, highlight how temperature sensitivity varies over the course of development. Here we couple United States Department of Agriculture yield and development data from 1981-2012 with weather station data to resolve temperature sensitivity according to both region and growth interval. On average, temperature sensitivity peaks during silking and grain filling, but there are major regional variations. In Northern states grain filling phases are shorter when temperatures are higher, whereas Southern states show little yield sensitivity and have longer grain filling phases during hotter seasons. This pattern of grain filling sensitivity and duration accords with the whole-season temperature sensitivity in US maize identified in recent studies. Further exploration of grain filling duration and its response to high temperatures may be useful in determining the degree to which maize agriculture can be adapted to a hotter climate.

  15. Silicon Nanowires with High-k Hafnium Oxide Dielectrics for Sensitive Detection of Small Nucleic Acid Oligomers

    PubMed Central

    Dorvel, Brian R.; Reddy, Bobby; Go, Jonghyun; Guevara, Carlos Duarte; Salm, Eric; Alam, Muhammad Ashraful; Bashir, Rashid

    2012-01-01

    Nanobiosensors based on silicon nanowire field effect transistors offer advantages of low cost, label-free detection, and potential for massive parallelization. As a result, these sensors have often been suggested as an attractive option for applications in Point-of-care (POC) medical diagnostics. Unfortunately, a number of performance issues such as gate leakage and current instability due to fluid contact, have prevented widespread adoption of the technology for routine use. High-k dielectrics, such as hafnium oxide (HfO2), have the known ability to address these challenges by passivating the exposed surfaces against destabilizing concerns of ion transport. With these fundamental stability issues addressed, a promising target for POC diagnostics and SiNWFET’s has been small oligonucleotides, more specifically microRNA (miRNA). MicroRNA’s are small RNA oligonucleotides which bind to messenger RNA’s, causing translational repression of proteins, gene silencing, and expressions are typically altered in several forms of cancer. In this paper, we describe a process for fabricating stable HfO2 dielectric based silicon nanowires for biosensing applications. Here we demonstrate sensing of single stranded DNA analogues to their microRNA cousins using miR-10b and miR-21 as templates, both known to be upregulated in breast cancer. We characterize the effect of surface functionalization on device performance using the miR-10b DNA analogue as the target sequence and different molecular weight poly-l-lysine as the functionalization layer. By optimizing the surface functionalization and fabrication protocol, we were able to achieve <100fM detection levels of miR-10b DNA analogue, with a theoretical limit of detection of 1fM. Moreover, the non-complementary DNA target strand, based on miR-21, showed very little response, indicating a highly sensitive and highly selective biosensing platform. PMID:22695179

  16. Correlation of the ionisation response at selected points of IC sensitive regions with SEE sensitivity parameters under pulsed laser irradiation

    SciTech Connect

    Gordienko, A V; Mavritskii, O B; Egorov, A N; Pechenkin, A A; Savchenkov, D V

    2014-12-31

    The statistics of the ionisation response amplitude measured at selected points and their surroundings within sensitive regions of integrated circuits (ICs) under focused femtosecond laser irradiation is obtained for samples chosen from large batches of two types of ICs. A correlation between these data and the results of full-chip scanning is found for each type. The criteria for express validation of IC single-event effect (SEE) hardness based on ionisation response measurements at selected points are discussed. (laser applications and other topics in quantum electronics)

  17. Pain Sensitivity is Inversely Related to Regional Grey Matter Density in the Brain

    PubMed Central

    Emerson, Nichole M.; Zeidan, Fadel; Lobanov, Oleg V.; Hadsel, Morten S.; Martucci, Katherine T.; Quevedo, Alexandre S.; Starr, Christopher J.; Nahman-Averbuch, Hadas; Weissman-Fogel, Irit; Granovsky, Yelena; Yarnitsky, David; Coghill, Robert C.

    2014-01-01

    Pain is a highly personal experience that varies substantially among individuals. In search of an anatomical correlate of pain sensitivity we used voxel-based morphometry (VBM) to investigate the relationship between grey matter density across the whole brain and inter-individual differences in pain sensitivity in 116 healthy volunteers (62 females, 54 males). Structural MRI and psychophysical data from 10 previous fMRI studies were used. Age, sex, unpleasantness ratings, scanner sequence, and sensory testing location were added to the model as covariates. Regression analysis of grey matter density across the whole brain and thermal pain intensity ratings at 49°C revealed a significant inverse relationship between pain sensitivity and grey matter density in bilateral regions of the posterior cingulate cortex, precuneus, intraparietal sulcus, and inferior parietal lobule. Unilateral regions of the left primary somatosensory cortex also exhibited this inverse relationship. No regions exhibited a positive relationship to pain sensitivity. These structural variations occurred in areas associated with the default mode network, attentional direction and shifting, as well as somatosensory processing. These findings underscore the potential importance of processes related to default mode thought and attention in shaping individual differences in pain sensitivity and indicate that pain sensitivity can potentially be predicted on the basis of brain structure. PMID:24333778

  18. Ultrahigh-sensitivity single-photon detection with linear-mode silicon avalanche photodiode.

    PubMed

    Akiba, Makoto; Tsujino, Kenji; Sasaki, Masahide

    2010-08-01

    We developed an ultrahigh-sensitivity single-photon detector using a linear-mode avalanche photodiode (APD) with a cryogenic low-noise readout circuit; the APD is operated at 78K. The noise-equivalent power of the detector is as low as 2.2x10(-20)W/Hz(1/2) at a wavelength of 450nm. The photon-detection efficiency and dark-count rate (DCR) are 0.72 and 0.0008counts/s, respectively. A low DCR is achieved by thermal treatment for reducing the trapped carriers when the thermal treatment temperature is above 100K. PMID:20680078

  19. Sensitivity of soil moisture initialization for decadal predictions under different regional climatic conditions in Europe

    NASA Astrophysics Data System (ADS)

    Khodayar, S.; Sehlinger, A.; Feldmann, H.; Kottmeier, C.

    2015-12-01

    The impact of soil initialization is investigated through perturbation simulations with the regional climate model COSMO-CLM. The focus of the investigation is to assess the sensitivity of simulated extreme periods, dry and wet, to soil moisture initialization in different climatic regions over Europe and to establish the necessary spin up time within the framework of decadal predictions for these regions. Sensitivity experiments consisted of a reference simulation from 1968 to 1999 and 5 simulations from 1972 to 1983. The Effective Drought Index (EDI) is used to select and quantify drought status in the reference run to establish the simulation time period for the sensitivity experiments. Different soil initialization procedures are investigated. The sensitivity of the decadal predictions to soil moisture initial conditions is investigated through the analysis of water cycle components' (WCC) variability. In an episodic time scale the local effects of soil moisture on the boundary-layer and the propagated effects on the large-scale dynamics are analysed. The results show: (a) COSMO-CLM reproduces the observed features of the drought index. (b) Soil moisture initialization exerts a relevant impact on WCC, e.g., precipitation distribution and intensity. (c) Regional characteristics strongly impact the response of the WCC. Precipitation and evapotranspiration deviations are larger for humid regions. (d) The initial soil conditions (wet/dry), the regional characteristics (humid/dry) and the annual period (wet/dry) play a key role in the time that soil needs to restore quasi-equilibrium and the impact on the atmospheric conditions. Humid areas, and for all regions, a humid initialization, exhibit shorter spin up times, also soil reacts more sensitive when initialised during dry periods. (e) The initial soil perturbation may markedly modify atmospheric pressure field, wind circulation systems and atmospheric water vapour distribution affecting atmospheric stability

  20. Performances of THz cameras with enhanced sensitivity in sub-terahertz region

    NASA Astrophysics Data System (ADS)

    Oda, Naoki; Ishi, Tsutomu; Kurashina, Seiji; Sudou, Takayuki; Morimoto, Takao; Miyoshi, Masaru; Doi, Kohei; Goto, Hideki; Sasaki, Tokuhito; Isoyama, Goro; Kato, Ryukou; Irizawa, Akinori; Kawase, Keigo

    2015-05-01

    Uncooled microbolometer-type 640x480 and 320x240 Terahertz (THz) focal plane arrays (FPAs) with enhanced sensitivity in sub-THz region are developed, and incorporated into 640x480 and 320x240 cameras, respectively. The pixel in the THz-FPA has such a structure that an area sensitive to electromagnetic wave is suspended above read-out integrated circuit (ROIC). A thin metallic layer is formed on the top of the sensitive area, while a thick metallic layer is formed on the surface of ROIC. The structure composed of the thin metallic layer and the thick metallic layer behaves as an optical cavity. The THz-FPAs reported in this paper have a modified pixel structure which has several times longer optical-cavity length than NEC's previous pixel does, by forming a thick SiN layer on the ROIC. The extended optical-cavity structure is favorable for detecting electromagnetic wave with lower frequency. Consequently, the Minimum Detectable Power per pixel (MDP) is improved ten times in sub-THz region, especially 0.5-0.6 THz. This paper presents spectral frequency dependences of MDP values for THz-FPA with the modified pixel structure and THz-FPA with the previous pixel structure, using THz free electron laser (FEL) developed by Osaka University. The modification of pixel structure extends high sensitivity region to lower frequency region, such as sub-THz region, and the wider spectral coverage of THz camera surely expands its applicability

  1. Silicon X-ray line emission from solar flares and active regions

    NASA Technical Reports Server (NTRS)

    Parkinson, J. H.; Wolff, R. S.; Kestenbaum, H. L.; Ku, W. H.-M.; Lemen, J. R.; Long, K. S.; Novick, R.; Suozzo, R. J.; Weisskopf, M. C.

    1978-01-01

    New observations of solar flare and active region X-ray spectra obtained with the Columbia University instrument on OSO-8 are presented and discussed. The high sensitivity of the graphite crystal panel has allowed both line and continuum spectra to be served with moderate spectral resolution. Observations with higher spectral resolution have been made with a panel of pentaerythritol crystals. Twenty-nine lines between 1.5 and 7.0 A have been resolved and identified, including several dielectronic recombination satellite lines to Si XIV and Si XIII lines which have been observed for the first time. It has been found that thermal continuum models specified by single values of temperature and emission measure have fitted the data adequately, there being good agreement with the values of these parameters derived from line intensity ratios.

  2. Regional and Local Scale Modeling of Stream Temperatures and Spatio-Temporal Variation in Thermal Sensitivities

    NASA Astrophysics Data System (ADS)

    Hilderbrand, Robert H.; Kashiwagi, Michael T.; Prochaska, Anthony P.

    2014-07-01

    Understanding variation in stream thermal regimes becomes increasingly important as the climate changes and aquatic biota approach their thermal limits. We used data from paired air and water temperature loggers to develop region-scale and stream-specific models of average daily water temperature and to explore thermal sensitivities, the slopes of air-water temperature regressions, of mostly forested streams across Maryland, USA. The region-scale stream temperature model explained nearly 90 % of the variation (root mean square error = 0.957 °C), with the mostly flat coastal plain streams having significantly higher thermal sensitivities than the steeper highlands streams with piedmont streams intermediate. Model R 2 for stream-specific models was positively related to a stream's thermal sensitivity. Both the regional and the stream-specific air-water temperature regression models benefited from including mean daily discharge from regional gaging stations, but the degree of improvement declined as a stream's thermal sensitivity increased. Although catchment size had no relationship to thermal sensitivity, steeper streams or those with greater amounts of forest in their upstream watershed were less thermally sensitive. The subset of streams with three or more summers of temperature data exhibited a wide range of annual variation in thermal sensitivity at a site, with the variation not attributable to discharge, precipitation patterns, or physical attributes of streams or their watersheds. Our findings are a useful starting point to better understand patterns in stream thermal regimes. However, a more spatially and temporally comprehensive monitoring network should increase understanding of stream temperature variation and its controls as climatic patterns change.

  3. Identification of a critical region in the Drosophila ryanodine receptor that confers sensitivity to diamide insecticides.

    PubMed

    Tao, Yong; Gutteridge, Steven; Benner, Eric A; Wu, Lihong; Rhoades, Daniel F; Sacher, Matthew D; Rivera, Michel A; Desaeger, Johan; Cordova, Daniel

    2013-09-01

    Anthranilic diamides, which include the new commercial insecticide, chlorantraniliprole, are an exciting new class of chemistry that target insect ryanodine receptors. These receptors regulate release of stored intracellular calcium and play a critical role in muscle contraction. As with insects, nematodes express ryanodine receptors and are sensitive to the plant alkaloid, ryanodine. However the plant parasitic nematode, Meloidogyne incognita, is insensitive to anthranilic diamides. Expression of a full-length Drosophila melanogaster ryanodine receptor in an insect cell line confers sensitivity to the receptor agents, caffeine and ryanodine along with nanomolar sensitivity to anthranilic diamides. Replacement of a 46 amino acid segment in a highly divergent region of the Drosophila C-terminus with that from Meloidogyne results in a functional RyR which lack sensitivity to diamide insecticides. These findings indicate that this region is critical to diamide sensitivity in insect ryanodine receptors. Furthermore, this region may contribute to our understanding of the differential selectivity diamides exhibit for insect over mammalian ryanodine receptors. PMID:23806522

  4. Caring for our natural community: Region 1. Threatened, endangered, and sensitive species program

    SciTech Connect

    Reel, S.; Schassberger, L.; Ruediger, W.

    1989-01-01

    This report is a summary of Region One's threatened, endangered, and sensitive plant, fish, and wildlife resources, as well as a summary of the program to conserve each species. The program information was developed at the field level and reflects what could be accomplished under existing Forest Plans.

  5. Sensitivity of simulated maize crop yields to regional climate in the Southwestern United States

    NASA Astrophysics Data System (ADS)

    Kim, S.; Myoung, B.; Stack, D.; Kim, J.; Hatzopoulos, N.; Kafatos, M.

    2013-12-01

    The sensitivity of maize yield to the regional climate in the Southwestern United States (SW US) has been investigated by using a crop-yield simulation model (APSIM) in conjunction with meteorological forcings (daily minimum and maximum temperature, precipitation, and radiation) from the North American Regional Reanalysis (NARR) dataset. The primary focus of this study is to look at the effects of interannual variations of atmospheric components on the crop productivity in the SW US over the 21-year period (1991 to 2011). First of all, characteristics and performance of APSIM was examined by comparing simulated maize yields with observed yields from United States Department of Agriculture (USDA) and the leaf-area index (LAI) from MODIS satellite data. Comparisons of the simulated maize yield with the available observations show that the crop model can reasonably reproduce observed maize yields. Sensitivity tests were performed to assess the relative contribution of each climate driver to regional crop yield. Sensitivity experiments show that potential crop production responds nonlinearly to climate drivers and the yield sensitivity varied among geographical locations depending on their mean climates. Lastly, a detailed analysis of both the spatial and temporal variations of each climate driver in the regions where maize is actually grown in three states (CA, AZ, and NV) in the SW US was performed.

  6. Position sensitive and energy dispersive x-ray detector based on silicon strip detector technology

    NASA Astrophysics Data System (ADS)

    Wiącek, P.; Dąbrowski, W.; Fink, J.; Fiutowski, T.; Krane, H.-G.; Loyer, F.; Schwamberger, A.; Świentek, K.; Venanzi, C.

    2015-04-01

    A new position sensitive detector with a global energy resolution for the entire detector of about 380 eV FWHM for 8.04 keV line at ambient temperature is presented. The measured global energy resolution is defined by the energy spectra summed over all strips of the detector, and thus it includes electronic noise of the front-end electronics, charge sharing effects, matching of parameters across the channels and other system noise sources. The target energy resolution has been achieved by segmentation of the strips to reduce their capacitance and by careful optimization of the front-end electronics. The key design aspects and parameters of the detector are discussed briefly in the paper. Excellent noise and matching performance of the readout ASIC and negligible system noise allow us to operate the detector with a discrimination threshold as low as 1 keV and to measure fluorescence radiation lines of light elements, down to Al Kα of 1.49 keV, simultaneously with measurements of the diffraction patterns. The measurement results that demonstrate the spectrometric and count rate performance of the developed detector are presented and discussed in the paper.

  7. Temperature-sensitive mutants identify crucial structural regions of simian virus 40 large T antigen.

    PubMed Central

    Loeber, G; Tevethia, M J; Schwedes, J F; Tegtmeyer, P

    1989-01-01

    We have completed the cloning and sequencing of all known temperature-sensitive, amino acid substitution mutants of simian virus 40 large T antigen (tsA mutants). Surprisingly, many of the mutants isolated from distinct viral strains by different laboratories are identical. Thus, 17 independently isolated mutants represent only eight distinct genotypes. This remarkable clustering of tsA mutations in a few "hot spots" in the amino acid sequence of T antigen and the temperature-sensitive phenotypes of the mutations strongly suggest that these amino acids play crucial roles in organizing the structure of one or more functional domains. Most of the mutations are located in highly conserved regions of T antigen that correlate with DNA binding, protein-protein interactions, or ATP binding. With the exception of one mutant with a lesion in the putative ATP-binding region, all the mutants are temperature sensitive for DNA replication. PMID:2778883

  8. Regional Glacier Sensitivity to Climate Change in the Monsoonal Himalaya: Implications for Water Resources

    NASA Astrophysics Data System (ADS)

    Rupper, S.; Maurer, J. M.; Schaefer, J. M.; Tsering, K.; Rinzin, T.; Dorji, C.; Johnson, E. S.; Cook, E. R.

    2014-12-01

    The rapid retreat of many glaciers in the monsoonal Himalaya is of potential societal concern. However, the retreat pattern in the region has been very heterogeneous, likely due in part to the inherent heterogeneity of climate and glaciers within the region. Assessing the impacts of glacier change on water resources, hydroelectric power, and hazard potential requires a detailed understanding of this potentially complex spatial pattern of glacier sensitivity to climate change. Here we quantify glacier surface-mass balance and meltwater flux across the entire glacierized region of the Bhutanese watershed using a full surface-energy and -mass balance model validated with field data. We then test the sensitivity of the glaciers to climatic change and compare the results to a thirty-year record of glacier volume changes. Bhutan is chosen because it (1) sits in the bulls-eye of the monsoon, (2) has >600 glaciers that exhibit the extreme glacier heterogeneity typical of the Himalayas, and (3) faces many of the economic and hazard challenges associated with glacier changes in the Himalaya. Therefore, the methods and results from this study should be broadly applicable to other regions of the monsoonal Himalaya. Our modeling results show a complex spatial pattern of glacier sensitivity to changes in climate across the Bhutanese Himalaya. However, our results also show that <15% of the glaciers in Bhutan account for >90% of the total meltwater flux, and that these glaciers are uniformly the glaciers most sensitive to changes in temperature (and less sensitive to other climate variables). We compare these results to a thirty-year record of glacier volume changes over the same region. In particular, we extract DEMs and orthorectified imagery from 1976 historical spy satellite images and 2006 ASTER images. DEM differencing shows that the glaciers that have changed most over the past thirty years also have the highest modeled temperature sensitivity. These results suggest that

  9. Vegetation sensitivity to global anthropogenic carbon dioxide emissions in a topographically complex region

    USGS Publications Warehouse

    Diffenbaugh, N.S.; Sloan, L.C.; Snyder, M.A.; Bell, J.L.; Kaplan, J.; Shafer, S.L.; Bartlein, P.J.

    2003-01-01

    Anthropogenic increases in atmospheric carbon dioxide (CO2) concentrations may affect vegetation distribution both directly through changes in photosynthesis and water-use efficiency, and indirectly through CO2-induced climate change. Using an equilibrium vegetation model (BIOME4) driven by a regional climate model (RegCM2.5), we tested the sensitivity of vegetation in the western United States, a topographically complex region, to the direct, indirect, and combined effects of doubled preindustrial atmospheric CO2 concentrations. Those sensitivities were quantified using the kappa statistic. Simulated vegetation in the western United States was sensitive to changes in atmospheric CO2 concentrations, with woody biome types replacing less woody types throughout the domain. The simulated vegetation was also sensitive to climatic effects, particularly at high elevations, due to both warming throughout the domain and decreased precipitation in key mountain regions such as the Sierra Nevada of California and the Cascade and Blue Mountains of Oregon. Significantly, when the direct effects of CO2 on vegetation were tested in combination with the indirect effects of CO2-induced climate change, new vegetation patterns were created that were not seen in either of the individual cases. This result indicates that climatic and nonclimatic effects must be considered in tandem when assessing the potential impacts of elevated CO2 levels.

  10. Direct Detection of Transcription Factors in Cotyledons during Seedling Development Using Sensitive Silicon-Substrate Photonic Crystal Protein Arrays1[OPEN

    PubMed Central

    Jones, Sarah I.; Tan, Yafang; Shamimuzzaman, Md; George, Sherine; Cunningham, Brian T.; Vodkin, Lila

    2015-01-01

    Transcription factors control important gene networks, altering the expression of a wide variety of genes, including those of agronomic importance, despite often being expressed at low levels. Detecting transcription factor proteins is difficult, because current high-throughput methods may not be sensitive enough. One-dimensional, silicon-substrate photonic crystal (PC) arrays provide an alternative substrate for printing multiplexed protein microarrays that have greater sensitivity through an increased signal-to-noise ratio of the fluorescent signal compared with performing the same assay upon a traditional aminosilanized glass surface. As a model system to test proof of concept of the silicon-substrate PC arrays to directly detect rare proteins in crude plant extracts, we selected representatives of four different transcription factor families (zinc finger GATA, basic helix-loop-helix, BTF3/NAC [for basic transcription factor of the NAC family], and YABBY) that have increasing transcript levels during the stages of seedling cotyledon development. Antibodies to synthetic peptides representing the transcription factors were printed on both glass slides and silicon-substrate PC slides along with antibodies to abundant cotyledon proteins, seed lectin, and Kunitz trypsin inhibitor. The silicon-substrate PC arrays proved more sensitive than those performed on glass slides, detecting rare proteins that were below background on the glass slides. The zinc finger transcription factor was detected on the PC arrays in crude extracts of all stages of the seedling cotyledons, whereas YABBY seemed to be at the lower limit of their sensitivity. Interestingly, the basic helix-loop-helix and NAC proteins showed developmental profiles consistent with their transcript patterns, indicating proof of concept for detecting these low-abundance proteins in crude extracts. PMID:25635113

  11. Regional Fast Cloud Feedback Assessment As Constraint on Global Climate Sensitivity

    NASA Astrophysics Data System (ADS)

    Quaas, J.; Kuehne, P.; Block, K.; Salzmann, M.

    2014-12-01

    Uncertainty in climate sensitivity estimates from models relates to inter-model spread in cloud-climate feedback. A sizeable component of the cloud-climate feedback is due to fast adjustments to altered CO2 profiles. This suggests the emerging large-domain season-long cloud-resolving simulations might become useful as reference simulation when performing sensitivity simulations with doubled CO2 concentrations. We assessed the fast cloud feedback in the CMIP5 multi-model ensemble of general circulation models (GCM) to find that in the chosen example region of Central Europe the fast cloud feedback behaves similarly as it does over global land areas in indivual models, yet shows a large inter-model scatter. This result is discussed with respect to the question whether a regional high-resolved model might be suitable to constrain global cloud feedbacks.

  12. Study of the Intergranular Corrosion of Sensitized UNS S31803 Stainless Steel in Transpassive Region

    NASA Astrophysics Data System (ADS)

    Morshed Behbahani, Khashayar; Najafisayar, Pooria; Pakshir, Mahmoud

    2016-06-01

    In this study, intergranular corrosion behavior of UNS S31803 duplex stainless steel was investigated using conventional potentiodynamic polarization, double loop electrochemical potentiokinetic reactivation (DLEPR), and electrochemical impedance spectroscopy (EIS) technique carried out at different potentials in the transpassive region. Different types of heat treatments were used to obtain samples with different degrees of sensitization. The results of the DLEPR tests showed that the solution-annealed sample and that was sensitized for half an hour would be considered as nonsensitized ones. Moreover, the sample that was sensitized for 24 h exhibits the highest value of the degree of sensitization. Polarization test results showed a typical active-passive behavior from which the transpassive potential range was determined and used as the range of the applied DC bias in the EIS experiments. Three different AC responses (including capacitive and inductive responses) were observed depending on the value of applied DC bias in the EIS experiments. In addition, it was observed that the presence of the second inductive loop at high applied DC bias is due to the adsorption of nonsoluble corrosion products on the surface of the samples. Moreover, the fitted values to the charge transfer and polarization resistances (R ct and R P) decreased as the sensitization time increased from 30 min to 24 h. Such observations were in good accordance with the metallographic examination of the corroded surfaces, carried out by optical and scanning electron microscopy techniques, revealing discontinuous grain boundary attack in nonsensitized samples and a continuous network of grain boundary attack in the case of sensitized ones. Moreover, as the applied DC bias increases the ferrite phase attack also occurs in the sensitized samples. In addition, approximately no pitting corrosion was observed on the surface of the corroded samples which is in accordance with their respective cyclic

  13. Determining Regional Sensitivity to Energy-Related Water Withdrawals in Minnesota

    NASA Astrophysics Data System (ADS)

    McCulloch, A.; Brauman, K. A.

    2015-12-01

    Minnesota has abundant freshwater resources, yet concerns about water-impacts of energy and mining development are increasing. Statewide, total annual water withdrawals have increased, and, in some watersheds, withdrawals make up a large fraction of available water. The energy and mining sectors play a critical role in determining water availability, as water is used to irrigate biofuel feedstock crops, cool thermoelectric plants, and process and transport fuels and iron ore. We evaluated the Minnesota Department of Natural Resources (DNR) Water and Reporting System (MPARS) dataset (1988-2014) to identify regions where energy and mining-related water withdrawals are high or where they are increasing. The energy and mining sectors account for over 65 percent of total water extractions in Minnesota, but this percentage is greater in some regions. In certain southern and northeastern Minnesota watersheds, these extractions account for 90 percent of total water demand. Sensitivity to these demands is not dependent on total water demand alone, and is also not uniform among watersheds. We identified and evaluated factors influencing sensitivity, including population, extraction type (surface water or groundwater), percentage of increased demand, and whether withdrawals are consumptive or not. We determined that southern Minnesota is particularly sensitive to increased water demands, because of growing biofuel and sand extraction industries (the products of which are used in hydraulic fracturing). In the last ten years, ethanol production in Minnesota has increased by 440 percent, and over fifteen refineries (each with a capacity over 1.1 billion gallons), have been built. These users primarily extract from surface water bodies within a few watersheds, compromising local supplies. As these energy-related industries continue to grow, so will the demand for freshwater resources. Determining regional sensitivity to increased demands will allow policy-makers to manage the

  14. Geographical location and key sensitivity issues of post-industrial regions in Europe.

    PubMed

    Stuczynski, Tomasz; Siebielec, Grzegorz; Korzeniowska-Puculek, Renata; Koza, Piotr; Pudelko, Rafal; Lopatka, Artur; Kowalik, Monika

    2009-04-01

    Primary objectives of our work were to spatially delineate post industrial areas of the EU-27 and indicate key environmental, social and economic sensitivity issues for these regions. The density of industrial sites within NUTS-x regions for EU-27 countries was assessed by using CORINE 2000 land cover layer. A development of postindustrial society in Europe represents a strong geographic diversity. There are distinct historical and current differences between regions which form major groups, comprising similar internal characteristics and definable trends in environmental and socioeconomic sense. Regions grouped into postindustrial clusters are fundamentally different from the European average, and are facing specific problems related to global market and political changes. Eastern postindustrial regions can be characterized as socially and economically weak, exhibiting high unemployment rate, low GDP, negative population growth and a strong environmental pressure, represented by a high density of dump sites. Most of the western EU postindustrial areas have been successfully recovered and moved into new economy as shown by most of the indicators. In urban postindustrial zones, however, emission sources of pollutants seem to continually be a major problem--not necessarily in terms of exceeding thresholds, but through a remarkable difference in the amount of pollutants produced relative to other regions. PMID:18437515

  15. Stochastic uncertainties and sensitivities of a regional-scale transport model of nitrate in groundwater

    NASA Astrophysics Data System (ADS)

    van den Brink, Cors; Zaadnoordijk, Willem Jan; Burgers, Saskia; Griffioen, Jasper

    2008-11-01

    SummaryGroundwater quality management relies more and more on models in recent years. These models are used to predict the risk of groundwater contamination for various land uses. This paper presents an assessment of uncertainties and sensitivities to input parameters for a regional model. The model had been set up to improve and facilitate the decision-making process between stakeholders and in a groundwater quality conflict. The stochastic uncertainty and sensitivity analysis comprised a Monte Carlo simulation technique in combination with a Latin hypercube sampling procedure. The uncertainty of the calculated concentrations of nitrate leached into groundwater was assessed for the various combinations of land use, soil type, and depth of the groundwater table in a vulnerable, sandy region in The Netherlands. The uncertainties in the shallow groundwater were used to assess the uncertainty of the nitrate concentration in the abstracted groundwater. The confidence intervals of the calculated nitrate concentrations in shallow groundwater for agricultural land use functions did not overlap with those of non-agricultural land use such as nature, indicating significantly different nitrate leaching in these areas. The model results were sensitive for almost all input parameters analyzed. However, the NSS is considered pretty robust because no shifts in uncertainty between factors occurred between factors towards systematic changes in fertilizer and manure inputs of the scenarios. In view of these results, there is no need to collect more data to allow science based decision-making in this planning process.

  16. Sensitivity analysis of the tidal representation in Singapore Regional Waters in a data assimilation environment

    NASA Astrophysics Data System (ADS)

    Kurniawan, Alamsyah; Ooi, Seng Keat; Hummel, Stef; Gerritsen, Herman

    2011-08-01

    The Singapore Regional Waters (SRW) is one of the more complex tidal regions in the world. This complexity is caused by various factors including the interaction of the Indian and Pacific oceans with their mainly semi-diurnal and diurnal tide, respectively, complicated coastline geometry, small islands and sharply varying bottom topography. Tidal data analysis is hampered by the lack of reliable coastal stations with long-term water level records while numerical tidal modelling studies suffer from lack of accurate high-resolution bathymetry data and uncertainty in the prescription of the tidal open boundary forcing. The present study combines numerical modelling with available along-track satellite altimetry data and a limited set of reliable coastal stations. It proposes a structured approach to study the sensitivity of tidal propagation and interactions to parameters like the prescription of tidal forcing at the open ocean boundaries, local depth information and seabed roughness. To guide and facilitate this analysis, the open-source software environment OpenDA for sensitivity analysis and simultaneous parameter optimisation is used. In a user-controlled way, the vector difference error in tidal representation could so effectively be reduced by ~50%. The results confirm the benefit of using OpenDA in guiding the systematic exploration of the modelled tide and reducing the parameter uncertainties in different parts of the SRW region. OpenDA is also shown to reduce the repetitive nature of simultaneous parameter variation. Finally, the behaviour of the tide in the region and its sensitivities to changes in tidal boundary forcing and to local depth and friction variation in the narrow regions of the Malacca Strait is now much better understood. With most of the systematic errors reduced in the numerical model as a result of the sensitivity analysis, it is expected that the model can be applied to study tide-surge interaction and is much better suited for later

  17. Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

    1991-01-01

    Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

  18. Sensitivity of CoSi2 precipitation in silicon to extra-low dopant concentrations. II. First-principles calculations

    NASA Astrophysics Data System (ADS)

    Borodin, V. A.; Ganchenkova, M. G.; Ruault, M.-O.; Fortuna, F.

    2015-01-01

    The paper is the second part of the study on the influence of very low dopant content in silicon on CoSi2 precipitation during high-temperature cobalt ion implantation into transmission electron microscope samples. It deals with the computational justification of various assumptions used in Paper I when rationalizing the kinetics of cobalt clustering in ion-implanted intrinsic silicon (both undoped and containing low concentrations of phosphorus atoms). In particular, it is proven that divacancies are efficient nucleation centers for the new Co-Si phase. It is shown that the capture of vacancies and divacancies on phosphorus atoms increases their lifetime in silicon matrix, but practically does not affect the mechanism of their interaction with interstitial cobalt atoms. Finally, it is demonstrated that the mobility of phosphorus interstitials at temperatures of our experiment is orders of magnitude higher than might be expected from the published literature data.

  19. 3D numerical modeling for ultra-sensitive noninvasive size-dependent nanoparticle detection technique using subwavelength silicon microcavities

    NASA Astrophysics Data System (ADS)

    Dionne, Jeffrey P.; Kuznetsova, Lyuba

    2015-08-01

    Three-dimensional finite-element-method simulations are used to investigate a system consisting of a subwavelength silicon microdisk cavity for the detection of different viruses of the same type. This is done by observing the effects that a spherical nanoparticle had on the frequency resonances of WGMs of the silicon microdisk. Results show that the observed spectral shift vary for the TM15 mode with an attached nanoparticle of radiuses between 100-300 nm. This frequency shift size-dependence makes it possible the for mature and immature HIV-1 viruses to be identified by the resonant frequency change in the transmission spectrum.

  20. Estimating the Sensitivity of Regional Dust Sources to Sea Surface Temperature Anomaly Patterns

    NASA Astrophysics Data System (ADS)

    Hoffman, A.; Forest, C. E.

    2014-12-01

    Mineral aerosols are an increasingly important component of the climate system that affect the radiative budget, nutrient cycles, and human environments. Dust emissions are largely controlled by regional climate factors such as atmospheric stability, precipitation, soil moisture, and vegetation. Regional climates, particularly within the tropics, are affected by teleconnections excited by sea surface temperatures. We therefore explore the impact of sea surface temperature (SST) anomaly patterns on local climates in major dust source regions (including southern Africa, the Arabian Desert, the Lake Eyre basin, and three others in North Africa) to help understand variability in the global dust cycle. We investigate the sensitivity of regional climate variables impacting mineral aerosol emissions to global SST anomaly patterns by estimating the global teleconnection operator (GTO), which relates regional climate responses to SST anomaly patterns. We estimate the GTO using the NCAR Community Atmosphere Model version 5.0 (CAM5.0) forced by an ensemble of randomly perturbed climatological SST fields. Variability in dust emissions are connected to SST anomaly patterns in the tropical oceans, particularly in the Indian and western Pacific Oceans. Teleconnections excited by remote SST anomalies typically modify dust emissions via near-surface circulation changes that impact friction velocity. However, the impact of SST-driven changes on threshold friction velocity can be on the same order of magnitude as those of friction velocity, suggesting the impact of SST anomalies on surface conditions are also significant. We reconstruct historical climates using the GTO and compare the results to a non-linear model and observations to assess the GTO capabilities and to identify ocean basins with the strongest influence on major dust source regions. Recognizing SST anomaly patterns as a component of internal variability in regional dust emissions helps characterize the impact of human

  1. Sensitivity of northwestern North Atlantic shelf circulation to surface and boundary forcing: A regional model assessment

    NASA Astrophysics Data System (ADS)

    Brennan, Catherine E.; Bianucci, Laura; Fennel, Katja

    2014-05-01

    The northwestern North Atlantic shelf circulation, influenced by both North Atlantic subpolar and subtropical gyres, is one of the hydrographically most variable regions in the North Atlantic Ocean and hosts biologically rich and productive fishing grounds. With the goal of simulating conditions in this productive and complex region, we implemented a nested regional ocean model for the northwest North Atlantic shelves including the Gulf of Maine, the Scotian Shelf, the Gulf of St. Lawrence, the Grand Banks, and the adjacent deep ocean. Configuring such a model requires choosing external data to supply surface forcing and initial and boundary conditions, as well as the consideration of nesting options. Although these selections can greatly affect model performance and results, often they are not systematically investigated. Here we assessed the sensitivity of our regional model to a suite of atmospheric forcing datasets, to sets of initial and boundary conditions constructed from multiple global ocean models and a larger scale regional ocean model, and to two variants of the model grid - one extending further off-shelf and resolving Flemish Cap topography. We conducted model simulations for a 6-year period and assessed model performance relative to a regional climatological dataset of temperature and salinity, observations collected from multiple monitoring stations and cruise transect lines, satellite sea surface temperature (SST) data, and descriptions of regional currents from literature. Based on this model assessment, we determined the model configuration that best reproduces observations. We find that while all surface forcing datasets are capable of producing model SST close to observed, the different datasets result in significant differences in model sea surface salinity (SSS). We find that initial and boundary conditions based on global ocean models do not necessary produce realistic circulation, and climatological initial and boundary conditions can

  2. Characterization of the heavily doped emitter and junction regions of silicon solar cells using an electron beam

    NASA Technical Reports Server (NTRS)

    Luke, K. L.; Cheng, L.-J.

    1986-01-01

    Heavily doped emitter and junction regions of silicon solar cells are investigated by means of the electron-beam-induced-current (EBIC) technique. Although the experimental EBIC data are collected under three-dimensional conditions, it is analytically demonstrated with two numerical examples that the solutions obtained with one-dimensional numerical modeling are adequate. EBIC data for bare and oxide-covered emitter surfaces are compared with theory. The improvement in collection efficiency when an emitter surface is covered with a 100-A SiO2 film varies with beam energy; for a cell with a junction depth of 0.35 microns, the improvement is about 54 percent at 2 keV.

  3. Effects of reward sensitivity and regional brain volumes on substance use initiation in adolescence.

    PubMed

    Urošević, Snežana; Collins, Paul; Muetzel, Ryan; Schissel, Ann; Lim, Kelvin O; Luciana, Monica

    2015-01-01

    This longitudinal study examines associations between baseline individual differences and developmental changes in reward [i.e. behavioral approach system (BAS)] sensitivity and relevant brain structures' volumes to prospective substance use initiation during adolescence. A community sample of adolescents ages 15-18 with no prior substance use was assessed for substance use initiation (i.e. initiation of regular alcohol use and/or any use of other substances) during a 2-year follow-up period and for alcohol use frequency in the last year of the follow-up. Longitudinal 'increases' in BAS sensitivity were associated with substance use initiation and increased alcohol use frequency during the follow-up. Moreover, adolescents with smaller left nucleus accumbens at baseline were more likely to initiate substance use during the follow-up period. This study provides support for the link between developmental increases in reward sensitivity and substance use initiation in adolescence. The study also emphasizes the potential importance of individual differences in volumes of subcortical regions and their structural development for substance use initiation during adolescence. PMID:24526186

  4. A possible functional localizer for identifying brain regions sensitive to sentence-level prosody

    PubMed Central

    Fedorenko, Evelina; Hsieh, Po-Jang; Balewski, Zuzanna

    2013-01-01

    Investigations of how we produce and perceive prosodic patterns are not only interesting in their own right but can inform fundamental questions in language research. We here argue that functional magnetic resonance imaging (fMRI) in general – and the functional localization approach in particular (e.g., Kanwisher et al., 1997; Saxe et al., 2006; Fedorenko et al., 2010; Nieto-Castañon & Fedorenko, 2012) – has the potential to help address open research questions in prosody research and at the intersection of prosody and other domains. Critically, this approach can go beyond questions like “where in the brain does mental process x produce activation” and toward questions that probe the nature of the representations and computations that subserve different mental abilities. We describe one way to functionally define regions sensitive to sentence-level prosody in individual subjects. This or similar “localizer” contrasts can be used in future studies to test hypotheses about the precise contributions of prosody-sensitive brain regions to prosodic processing and cognition more broadly. PMID:25642425

  5. The LHCb Silicon Tracker

    NASA Astrophysics Data System (ADS)

    Tobin, Mark

    2013-12-01

    The LHCb experiment is designed to perform high-precision measurements of CP violation and search for new physics using the enormous flux of beauty and charm hadrons produced at the LHC. The LHCb detector is a single-arm spectrometer with excellent tracking and particle identification capabilities. The Silicon Tracker is part of the tracking system and measures very precisely the particle trajectories coming from the interaction point in the region of high occupancies around the beam axis. The LHCb Silicon Tracker covers a total sensitive area of about 12 m2 using silicon micro-strip detectors with long readout strips. It consists of one four-layer tracking station before the LHCb dipole magnet and three stations after. The detector has performed extremely well since the start of the LHC operation despite the fact that the experiment is collecting data at instantaneous luminosities well above the design value. This paper reports on the operation and performance of the Silicon Tracker during the Physics data taking at the LHC during the last two years.

  6. Singlet oxygen sensitizing materials based on porous silicone: photochemical characterization, effect of dye reloading and application to water disinfection with solar reactors.

    PubMed

    Manjón, Francisco; Santana-Magaña, Montserrat; García-Fresnadillo, David; Orellana, Guillermo

    2010-06-01

    Photogeneration of singlet molecular oxygen ((1)O(2)) is applied to organic synthesis (photooxidations), atmosphere/water treatment (disinfection), antibiofouling materials and in photodynamic therapy of cancer. In this paper, (1)O(2) photosensitizing materials containing the dyes tris(4,4'-diphenyl-2,2'-bipyridine)ruthenium(II) (1, RDB(2+)) or tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (2, RDP(2+)), immobilized on porous silicone (abbreviated RDB/pSil and RDP/pSil), have been produced and tested for waterborne Enterococcus faecalis inactivation using a laboratory solar simulator and a compound parabolic collector (CPC)-based solar photoreactor. In order to investigate the feasibility of its reuse, the sunlight-exposed RDP/pSil sensitizing material (RDP/pSil-a) has been reloaded with RDP(2+) (RDP/pSil-r). Surprisingly, results for bacteria inactivation with the reloaded material have demonstrated a 4-fold higher efficiency compared to those of either RDP/pSil-a, unused RDB/pSil and the original RDP/pSil. Surface and bulk photochemical characterization of the new material (RDP/pSil-r) has shown that the bactericidal efficiency enhancement is due to aggregation of the silicone-supported photosensitizer on the surface of the polymer, as evidenced by confocal fluorescence lifetime imaging microscopy (FLIM). Photogenerated (1)O(2) lifetimes in the wet sensitizer-doped silicone have been determined to be ten times longer than in water. These facts, together with the water rheology in the solar reactor and the interfacial production of the biocidal species, account for the more effective disinfection observed with the reloaded photosensitizing material. These results extend and improve the operational lifetime of photocatalytic materials for point-of-use (1)O(2)-mediated solar water disinfection. PMID:20393668

  7. Estimating the sensitivity of regional dust sources to sea surface temperature patterns

    NASA Astrophysics Data System (ADS)

    Hoffman, Alexis L.; Forest, Chris E.; Li, Wei

    2014-09-01

    Exploring the impact of sea surface temperature (SST) anomaly patterns on local climate in major dust source regions helps clarify our understanding of variability in the global dust cycle. In contrast to previous work, this research focuses explicitly on the influence of SST anomalies on dust emissions and attempts to explain the mechanisms by which SST anomalies affect seasonal dust emissions. This study investigates the seasonal sensitivity of mineral aerosol emissions to SST anomaly patterns from the Bodele Depression, West Africa, Sahel, Kalahari Desert, Arabian Desert, and Lake Eyre basin. The global teleconnection operator, which relates regional climate responses to SST anomaly patterns, is estimated for relevant variables in an ensemble of the National Center for Atmospheric Research Community Atmosphere Model version 5 forced by randomly perturbed climatological SST fields. Variability in dust emissions from major dust sources is linked to tropical SST anomalies, particularly in the Indian and western Pacific Oceans. Teleconnections excited by remote SST anomalies typically impact dust emissions via changes in near-surface wind speeds and friction velocity. However, SST-driven impacts on the threshold friction velocity can be of the same order of magnitude as changes in the friction velocity, suggesting the impact of SST anomalies on precipitation and soil moisture is also significant. Identifying SST anomaly patterns as a component of internal variability in regional dust emissions helps characterize human influences on the dust cycle as well as improve predictions of climate, nutrient cycles, and human environments.

  8. Photo-thermo-refractive glass with sensitivity extended to near infrared region

    NASA Astrophysics Data System (ADS)

    Kompan, F.; Venus, G.; Glebova, L.; Mingareev, H.; Glebov, L.

    2016-02-01

    Photo-thermo-refractive (PTR) glass is a multicomponent silicate glass doped with Ce3+ and Ag+ which is extensively used for holographic recording of volume Bragg gratings (VBGs). Possibility of recording of advanced, complex holograms in the PTR glass is of current interest as it offers great opportunities in imaging and laser systems control. However, the glass does not have capabilities for recording of complex holograms with using light from the visible / IR spectral region due to its UV photosensitivity. Extension of the PTR-glass sensitivity range into the visible / IR spectral region was carried out by doping the original glass with trivalent terbium ions. Photosensitivity mechanism was implemented by means of excited state absorption using a UV photon and a visible photon for excitation of the Tb3+ 5d14f7 band. For the first time refractive index modulation on the order of 2x10-4 was obtained in PTR glass after exposure to the visible / IR light. Resulting magnitude of induced refractive index allows for high efficiency complex hologram fabrication in Tb3+ doped PTR glass for use which in the visible / IR region. Holographic capabilities of Tb3+ doped PTR glass were demonstrated by recording a complex hologram in the glass using green and blue light.

  9. Regional sensitivity analysis of aleatory and epistemic uncertainties on failure probability

    NASA Astrophysics Data System (ADS)

    Li, Guijie; Lu, Zhenzhou; Lu, Zhaoyan; Xu, Jia

    2014-06-01

    To analyze the effects of specific regions of the aleatory and epistemic uncertain variables on the failure probability, a regional sensitivity analysis (RSA) technique called contribution to failure probability (CFP) plot is developed in this paper. This RSA technique can detect the important aleatory and epistemic uncertain variables, and also measure the contribution of specific regions of these important input variables to failure probability. When computing the proposed CFP, the aleatory and epistemic uncertain variables are modeled by random and interval variables, respectively. Then based on the hybrid probabilistic and interval model (HPIM) and the basic probability assignments in evidence theory, the failure probability of the structure with aleatory and epistemic uncertainties can be obtained through a successive construction of the second-level limit state function and the corresponding reliability analysis. Kriging method is used to establish the surrogate model of the second-level limit state function to improve the computational efficiency. Two practical examples are employed to test the effectiveness of the proposed RSA technique, and the efficiency and accuracy of the established kriging-based solution.

  10. Sensitivity of the Maritime Continent precipitation to horizontal resolution in a coupled regional model

    NASA Astrophysics Data System (ADS)

    Li, Yue; Jourdain, Nicolas; Taschetto, Andréa; Gupta, Alex Sen; Masson, Sébastien; Cai, Wenju

    2015-04-01

    The Maritime Continent (MC) is centred at one of the major monsoon systems in the world. Characterized by massive tropical heating and precipitation, it is strongly influencing both the Hadley and Walker circulations. However, there are significant challenges in correctly represent climate of this region because of the complex topography and the arrangement of lands and seas. It is often argued that improved representation of the diurnal cycle over islands and the complex mesoscale circulation associated with land-sea contrast is important to energy and hydrological cycles of this region. To investigate the sensitivity of precipitation over the MC to model horizontal resolution, we perform three regional numerical experiments using the coupled NEMO-OASIS-WRF model at different horizontal resolutions of 3/4°, 1/4° and 1/12° in both atmosphere and ocean components. The 3/4° and 1/4° experiments are run on a large MC domain for 21 years (1989 to 2009), and the 1/12° experiment is nested within the 1/4° domain using two-way interactive nesting over 5 years. Increasing the resolution reduces biases in mean SST and mean precipitation. The precipitation distribution is also improved at higher resolution, particularly in coastal areas. A part of these improvements are related to different behaviours of the model physical schemes across the three resolutions. Other changes are interpreted in terms of land-sea breeze, that we describe through a new comprehensive method.

  11. Development of a Regional Velocity Model Using 3D Broadband Waveform Sensitivity

    NASA Astrophysics Data System (ADS)

    Panning, M. P.; Romanowicz, B. A.; Kim, A.

    2005-12-01

    We are developing a new approach which relies on a cascade of increasingly accurate theoretical approximations for computation of the seismic wavefield to develop a model of regional seismic velocity structure for eastern Eurasia using full seismic waveforms. The selected area is particularly suitable for the purpose of this experiment, as it is highly heterogeneous, presenting a challenge for standard modeling techniques, but it is well surrounded by earthquake sources and a significant number of high quality broadband digital stations exist, for which data are readily accessible through IRIS (Incorporated Research Institutions for Seismology) and the FDSN (Federation of Digital Seismic Networks). The initial model is derived from a large database of teleseismic long period waveforms (surface waves and overtone wavepackets) using well-developed theoretical approximations, the Path Average Approximation (PAVA) and Nonlinear Asymptotic Coupling Theory (NACT). These approaches assume waveforms are only sensitive to the 1D (PAVA) and 2D (NACT) structure in the vertical plane between source and receiver, which is adequate for the development of a smooth initial 3D velocity model. We refine this model using a more accurate theoretical approach. We utilize an implementation of a 3D Born approximation, which takes into account the contribution to the waveform from single scattering throughout the model, giving full 3D waveform sensitivity kernels. We perform verification tests of this approach for synthetic models, and show that it can accurately represent the wavefield as predicted by numerical approaches in several situations where approximations such as PAVA and NACT are insufficient. The Born 3D waveform sensitivity kernels are used to perform a higher resolution inversion of regional waveforms for a smaller subregion between longitudes 90 and 150 degrees E, and latitudes 15 and 40 degrees N. To further increase the accuracy of this model, we intend to utilize a very

  12. Sensitive, resistant and multi-drug resistant Acinetobacter baumanii at Saudi Arabia hospital eastern region.

    PubMed

    Ahmed, Mughis Uddin; Farooq, Reshma; Al-Hawashim, Nadia; Ahmed, Motasim; Yiannakou, Nearchos; Sayeed, Fatima; Sayed, Ali Rifat; Lutfullah, Sualiha

    2015-05-01

    Since the Physicians start use of antibiotics long ago with un-notice drug resistance. However actual problem was recognized about 85 years ago. Antibiotic resistant and Multi-drug resistant bacterial strains are at rise throughout the world. It is physicians and researchers to take scientific research based appropriate action to overcome this ever-spreading problem. This study is designed to find out sensitive (S), resistant (R) and multi-drug resistant (MDR) Acinetobacter baumanii strain along with other isolates in the resident patients of Eastern Region of Saudi Arabia. Pseudomonas aeruginosa is excluded from other gram-negative organisms isolated from different sites as it will be dealt separately. This study is based in was retrospective observations designed to collect data of different stains of Acinetobacter baumanii with reference to their Sensitivity (S), Resistance (R), Multi-Drug Resistance (MDR) along with other Gram negative isolated from different sites (from 1st January 2004 to 31st December 2011) at King Abdulaziz Hospital located Eastern Region of Kingdom of Saudi Arabia (KSA). All necessary techniques were used to culture and perform sensitivity of these isolates. There were 4532 isolates out of which 3018 (67%) were from patients. Out of Acinetobacter baumanii infected were 906 (20%) while other 3626 (80%) isolates were miscellaneous. Numbers of patients or cases were 480 (53%) out of 906 isolates and numbers of patients or cases in other organisms were 2538 (70%) out of 3626 isolates. Acinetobacter baumanii infected patients 221 (46%) were male and 259 (54%) were female and the male and female ratio of 1:1.2. In other organisms this male female ratio was almost same. There was steady rise in number of patients and the hence the isolates from 2004 to 2011. Majority of the bacterial strains were isolated as single organism but some were isolated as double or triple or quadruple or more organisms from different sites. Sensitive, Resistant and

  13. Sensitivity of CoSi2 precipitation in silicon to extra-low dopant concentrations. I. Experiment

    NASA Astrophysics Data System (ADS)

    Fortuna, F.; Ruault, M.-O.; Borodin, V. A.; Ganchenkova, M. G.; Kaïtasov, O.

    2015-01-01

    We demonstrate that the precipitation of cobalt disilicide phase in silicon during high-temperature (500 °C and 650 °C) implantation is noticeably affected by impurities of phosphorus and boron. Measurements of B-type CoSi2 cluster sizes and number densities as a function of implantation dose indicate that the number density of clusters progressively increases as the phosphorus concentration increases from 7 × 1011 to 8 × 1013 cm-3. A tentative explanation of these observations is proposed based on the previously suggested mechanism of precipitate nucleation, and on the results of first principles calculations summarized in Paper II, published as a follow-up paper. The results imply that utmost care is to be taken when dealing with transition metal precipitation during ion implantation into silicon because variations in the dopant content can affect the reproducibility of results even at extremely low dopant concentrations.

  14. Topography of prostaglandin H synthase. Antiinflammatory agents and the protease-sensitive arginine 253 region.

    PubMed

    Kulmacz, R J

    1989-08-25

    Prostaglandin H synthase catalyzes two reactions: the bis-dioxygenation of arachidonic acid to form prostaglandin G2 (cyclooxygenase activity), and the reduction of hydroperoxides to the corresponding alcohols (peroxidase activity). The cyclooxygenase activity can be selectively inhibited by many nonsteroidal antiinflammatory agents including indomethacin. In the native synthase, there is a single prominent protease-sensitive region, located near Arg253; binding of the heme prosthetic group makes the synthase resistant to proteases. To investigate the spatial relationship between the area of the synthase which interacts with indomethacin and the protease-sensitive region, the effects of indomethacin and similar agents on the protease sensitivity of the two enzymatic activities and of the synthase polypeptide were examined. Incubation of the synthase apoenzyme with trypsin (3.6% w/w) resulted in the time-dependent coordinate loss (75% at 1 h) of both enzymatic activities and the cleavage (85% at 1 h) of the 70-kDa subunit into 38- and 33-kDa fragments, indicating that proteolytic cleavage of the polypeptide at Arg253, destroyed both activities of the synthase simultaneously. Indomethacin, (S)-flurbiprofen, or meclofenamate (each at 20 microM) rendered both activities and the synthase polypeptide (at 5 microM subunit) resistant to attack by trypsin or proteinase K; these agents also inhibited the cyclooxygenase activity of the intact synthase. Two reversible cyclooxygenase inhibitors, ibuprofen and flufenamate, also made both of the activities and the synthase polypeptide more resistant to trypsin. Titration of the apoenzyme with indomethacin (0-3 mol/mol of synthase dimer) resulted in proportional increases in the inhibition of the cyclooxygenase and in the resistance to attack by trypsin. (R)-Flurbiprofen did not increase the resistance to protease or appreciably inhibit the cyclooxygenase. These results suggest that the same stereospecific interaction of these

  15. Quantum mechanical device modeling: FinFET having an isolated n+/p+ gate region strapped with poly-silicon.

    PubMed

    Kim, Han-Geon; Kim, Joong-Sik; Kim, Young-Kyu; Won, Taeyoung

    2007-11-01

    In this paper, we present our numerical study on FinFET having an isolated n+/p+ gate region strapped with metal and poly-silicon structure. Our theoretical work is based on 2-D quantum-mechanical simulator with a self-consistent solution of Poisson-Schrödinger equation. Our numerical simulation revealed that the threshold voltage (VT) is controlled within -0.1 approximately +0.2 V with varying the doping concentration of the n+ and p+ polysilicon gate region from 1.0 x 10(17) to 1.0 x 10(18) cm(-3). We also confirmed that the better VT tolerance of the FinFET on the variation of the fin thickness can be expected over the conventional FinFET structure. For instance, the VT of the FinFET under this work exhibited 0.02 V tolerance with respect to the variation of the fin thickness change of 5 nm (from 30 to 35 nm) while the traditional FinFET demonstrates the tolerance of 0.12 V for the same variation of the fin thickness. PMID:18047135

  16. Silicon metal-semiconductor-metal photodetector

    DOEpatents

    Brueck, Steven R. J.; Myers, David R.; Sharma, Ashwani K.

    1995-01-01

    Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

  17. Silicon metal-semiconductor-metal photodetector

    DOEpatents

    Brueck, Steven R. J.; Myers, David R.; Sharma, Ashwani K.

    1997-01-01

    Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

  18. metilene: fast and sensitive calling of differentially methylated regions from bisulfite sequencing data.

    PubMed

    Jühling, Frank; Kretzmer, Helene; Bernhart, Stephan H; Otto, Christian; Stadler, Peter F; Hoffmann, Steve

    2016-02-01

    The detection of differentially methylated regions (DMRs) is a necessary prerequisite for characterizing different epigenetic states. We present a novel program, metilene, to identify DMRs within whole-genome and targeted data with unrivaled specificity and sensitivity. A binary segmentation algorithm combined with a two-dimensional statistical test allows the detection of DMRs in large methylation experiments with multiple groups of samples in minutes rather than days using off-the-shelf hardware. metilene outperforms other state-of-the-art tools for low coverage data and can estimate missing data. Hence, metilene is a versatile tool to study the effect of epigenetic modifications in differentiation/development, tumorigenesis, and systems biology on a global, genome-wide level. Whether in the framework of international consortia with dozens of samples per group, or even without biological replicates, it produces highly significant and reliable results. PMID:26631489

  19. 20th century precipitation changes in the Sahel region: sensitivity studies with ECHAM5-HAM

    NASA Astrophysics Data System (ADS)

    Folini, D.; Baumgartner, D.; Wild, M.

    2012-04-01

    The 20th century has seen an enormous growth in population and industrialization. These changes are accompanied, among others, by a substantial increase in aerosol emission. To learn more about associated consequences for the climate system we have carried out a comparatively large set of transient sensitivity studies with the global atmosphere only climate model ECHAM5-HAM, using aerosol emission data from NIES (National Institute of Environmental Studies, Japan) and prescribed, observation based sea surface temperatures (SSTs) from the Hadley Center. The sensitivity studies cover the period from 1870 to 2005 and comprise ensembles of simulations (up to 13 members per ensemble), which allow to address the role of different aerosol species, greenhouse gases, and prescribed sea surface temperatures. We present a preliminary analysis of these global simulation data for the Sahel region (land within 20W / 35E / 10N / 20N). The annual cycle as well as the overall temporal evolution of precipitation in the Sahel according to CRU (Climate Research Unit, UK) is captured well by the model simulations: two comparatively wet phases in the 1930s and 1950s, a more or less continuous decline thereafter, and a renewed increase in precipitation since the 1980s. This decline / renewed incline since the 1950s is, however, about twice as strong in the CRU data than in the model data. The sensitivity studies reveal SSTs as a prominent factor for the time evolution of precipitation, while the atmosphere only effect of aerosols plays a minor role for the modeled precipitation. The observation based prescribed SSTs may, however, encapsulate and aerosol effect already.

  20. Sensitivity of ICTP Regional Climate Model (RegCM3) to Initial and Lateral Boundary Conditions

    NASA Astrophysics Data System (ADS)

    Nadeem, I.; Formayer, H.

    2009-04-01

    Regional climate simulations require lateral boundary conditions. These are typically reanalysis of past observations or alternatively, output from climate general circulation models. Lateral boundary conditions are available at various temporal and spatial resolutions. At present, spatial resolution of reanalysis datasets ranges from few kilometers, for example, regional reanalysis limited to only single continent, to the coarser but global datasets like ECMWF 40 Years Re-Analysis. While these datasets represent reasonable analyses of 3-D atmospheric as well as surface conditions, their resolutions, the physics of the models used to generate them, and the means of assimilating data into them can produce very different results when used as boundary conditions for regional climate models. The sensitivity of ICTP Regional Climate Model (RegCM3) to different lateral boundary conditions was investigated over the Alpine region. The model was run directly at 10km horizontal resolution as well as in one-way double nested mode, with a 30 km grid point spacing mother domain encompassing the Europe and a 10 km grid point spacing nested domain covering the Alpine Region. The simulations spans the one-year period of 1989. The boundary conditions used for various simulations were ECMWF Interim Re-Analysis (ERA-Interim, 0.75° and 1.5° grid spacings, 6-h intervals), the ECMWF 40 Years Re-Analysis (ERA40, 1° and 2.5° grid spacings, 6-h interval) and finally the 2.5°, 6-h NCEP/DOE AMIP-II Reanalysis (Reanalysis-2). Sea Surface Temperature for the simulated periods were obtained from a UK Met Office Global Ocean Surface Temperature (GISST), a set of SST data in monthly 1° area grids. When recently released ERA-Interim Reanalysis, which is based on a recent release of the Integrated Forecasting System (IFS Cy31r2) containing many improvements both in the forecasting model and analysis methodology, was used as lateral and boundary conditions, the simulated precipitation field

  1. Electrocatalytic activity of NiO on silicon nanowires with a carbon shell and its application in dye-sensitized solar cell counter electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Junhee; Jung, Cho-Long; Kim, Minsoo; Kim, Soomin; Kang, Yoonmook; Lee, Hae-Seok; Park, Jeounghee; Jun, Yongseok; Kim, Donghwan

    2016-03-01

    To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the resulting nanomaterial exhibits excellent electrocatalytic activity and performs well as a counter electrode for dye-sensitized solar cells (DSSCs). The compositions of the materials were examined using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. Their micro- and nano-structures were investigated using scanning electron microscopy and transmission electron microscopy. The electrochemical activity toward I-/I3- was examined using cyclic voltammetry and electrochemical impedance spectroscopy. The obtained peak power conversion efficiency of the DSSC based on the NiO@SiNW/C counter electrode was 9.49%, which was greater than that of the DSSC based on the Pt counter electrode.To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the

  2. Relationship between radiation dose and reduced X-ray sensitivity surrounding breast region using CR stimulable phosphor plate for mammography

    NASA Astrophysics Data System (ADS)

    Nishide, Hiroko; Kodera, Yoshie

    2015-03-01

    Computed radiography (CR) systems use a photostimulable phosphor plate (imaging plate ; IP) as a sensor for digital mammography. In clinical mammography, breast is almost exposed same region of IP, and therefor, direct x-ray regions surrounding suffer from reduced x-ray sensitivity. Consequently, the difference in x-ray sensitivity between the breast regions and the unattenuated x-ray region was obtained. However, radiation dose quantity that reduces x-ray sensitivity is not known. In this study, we imaged a breast phantom under fixed conditions, and subsequently, we investigated the pixel value differences between the breast region and the unattenuated x-ray regions. We measured the entrance air-kerma using 550 sensing elements of glass dosimeter, 22x25 lines, that were placed at the surface of the cassette including the IP. In order to measure the x-ray sensitivity, pre- and post-exposure breast phantom images were acquired after 500, 1,000, 1,350, and 1,500 trials. The pixel values were measured at four points; in the breast region and in the unattenuated x-ray region. The ratio of these pixel values was compared with the cumulative exposure dose. The ratio was nearly constant until 1,000 trials, but a significant reduction was observed after 1,350 trials. Further, in the image obtained after 1,500th trials, the shape of breast phantom could be observed. This image supports the fact that the x-ray sensitivity was lowered in the unattenuated x-ray region. The difference in the pixel value between the breast region and the unattenuated x-ray region was obtained over 1,000 exposures at 100,000 mAs.

  3. Assessment of future scenarios for wind erosion sensitivity changes based on ALADIN and REMO regional climate model simulation data

    NASA Astrophysics Data System (ADS)

    Mezősi, Gábor; Blanka, Viktória; Bata, Teodóra; Ladányi, Zsuzsanna; Kemény, Gábor; Meyer, Burghard C.

    2016-07-01

    The changes in rate and pattern of wind erosion sensitivity due to climate change were investigated for 2021-2050 and 2071-2100 compared to the reference period (1961-1990) in Hungary. The sensitivities of the main influencing factors (soil texture, vegetation cover and climate factor) were evaluated by fuzzy method and a combined wind erosion sensitivity map was compiled. The climate factor, as the driving factor of the changes, was assessed based on observed data for the reference period, while REMO and ALADIN regional climate model simulation data for the future periods. The changes in wind erosion sensitivity were evaluated on potentially affected agricultural land use types, and hot spot areas were allocated. Based on the results, 5-6% of the total agricultural areas were high sensitive areas in the reference period. In the 21st century slight or moderate changes of wind erosion sensitivity can be expected, and mostly `pastures', `complex cultivation patterns', and `land principally occupied by agriculture with significant areas of natural vegetation' are affected. The applied combination of multi-indicator approach and fuzzy analysis provides novelty in the field of land sensitivity assessment. The method is suitable for regional scale analysis of wind erosion sensitivity changes and supports regional planning by allocating priority areas where changes in agro-technics or land use have to be considered.

  4. Sensitivity of Regional Hydropower Generation to the Projected Changes in Future Watershed Hydrology

    NASA Astrophysics Data System (ADS)

    Kao, S. C.; Naz, B. S.; Gangrade, S.

    2015-12-01

    Hydropower is a key contributor to the renewable energy portfolio due to its established development history and the diverse benefits it provides to the electric power systems. With the projected change in the future watershed hydrology, including shift of snowmelt timing, increasing occurrence of extreme precipitation, and change in drought frequencies, there is a need to investigate how the regional hydropower generation may change correspondingly. To evaluate the sensitivity of watershed storage and hydropower generation to future climate change, a lumped Watershed Runoff-Energy Storage (WRES) model is developed to simulate the annual and seasonal hydropower generation at various hydropower areas in the United States. For each hydropower study area, the WRES model use the monthly precipitation and naturalized (unregulated) runoff as inputs to perform a runoff mass balance calculation for the total monthly runoff storage in all reservoirs and retention facilities in the watershed, and simulate the monthly regulated runoff release and hydropower generation through the system. The WRES model is developed and calibrated using the historic (1980-2009) monthly precipitation, runoff, and generation data, and then driven by a large set of dynamically- and statistically-downscaled Coupled Model Intercomparison Project Phase 5 climate projections to simulate the change of watershed storage and hydropower generation under different future climate scenarios. The results among different hydropower regions, storage capacities, emission scenarios, and timescales are compared and discussed in this study.

  5. Sensitivity to Spacing Information Increases More for the Eye Region than for the Mouth Region during Childhood

    ERIC Educational Resources Information Center

    de Heering, Adelaide; Schiltz, Christine

    2013-01-01

    Sensitivity to spacing information within faces improves with age and reaches maturity only at adolescence. In this study, we tested 6-16-year-old children's sensitivity to vertical spacing when the eyes or the mouth is the facial feature selectively manipulated. Despite the similar discriminability of these manipulations when they are…

  6. An accelerated stress testing program for determining the reliability sensitivity of silicon solar cells to encapsulation and metallization systems

    NASA Technical Reports Server (NTRS)

    Lathrop, J. W.; Davis, C. W.; Royal, E.

    1982-01-01

    The use of accelerated testing methods in a program to determine the reliability attributes of terrestrial silicon solar cells is discussed. Different failure modes are to be expected when cells with and without encapsulation are subjected to accelerated testing and separate test schedules for each are described. Unencapsulated test cells having slight variations in metallization are used to illustrate how accelerated testing can highlight different diffusion related failure mechanisms. The usefulness of accelerated testing when applied to encapsulated cells is illustrated by results showing that moisture related degradation may be many times worse with some forms of encapsulation than with no encapsulation at all.

  7. Influence of phosphorus on the reduction of silicon in regions characterized by droplet flow of the smelting products

    SciTech Connect

    V.A. Kim; N.V. Chainikova

    2008-08-15

    The influence of phosphorus on the thermodynamics of silicon reduction in Fe-Si-C melts is considered. The influence of the theoretical combustion temperature of coke in the tuyeres on the silicon content is studied in the blast-furnace smelting of low-phosphorus hot metal at AO Arcelor Mittal Temirtau.

  8. Highly sensitive silicon nanowire biosensor with novel liquid gate control for detection of specific single-stranded DNA molecules.

    PubMed

    Adam, Tijjani; Hashim, U

    2015-05-15

    The study demonstrates the development of a liquid-based gate-control silicon nanowire biosensor for detection of specific single-stranded DNA (ssDNA) molecules. The sensor was fabricated using conventional photolithography coupled with an inductively coupled plasma dry etching process. Prior to the application of DNA to the device, its linear response to pH was confirmed by serial dilution from pH 2 to pH 14. Then, the sensor surface was silanized and directly aminated with (3-aminopropyl) triethoxysilane to create a molecular binding chemistry for biofunctionalization. The resulting Si‒O‒Si‒ components were functionalized with receptor ssDNA, which interacted with the targeted ssDNA to create a field across the silicon nanowire and increase the current. The sensor shows selectivity for the target ssDNA in a linear range from target ssDNA concentrations of 100 pM to 25 nM. With its excellent detection capabilities, this sensor platform is promising for detection of specific biomarkers and other targeted proteins. PMID:25453738

  9. Sensitivity of CoSi{sub 2} precipitation in silicon to extra-low dopant concentrations. I. Experiment

    SciTech Connect

    Fortuna, F.; Ruault, M.-O.; Kaïtasov, O.; Borodin, V. A.; Ganchenkova, M. G.

    2015-01-28

    We demonstrate that the precipitation of cobalt disilicide phase in silicon during high-temperature (500 °C and 650 °C) implantation is noticeably affected by impurities of phosphorus and boron. Measurements of B-type CoSi{sub 2} cluster sizes and number densities as a function of implantation dose indicate that the number density of clusters progressively increases as the phosphorus concentration increases from 7 × 10{sup 11} to 8 × 10{sup 13 }cm{sup −3}. A tentative explanation of these observations is proposed based on the previously suggested mechanism of precipitate nucleation, and on the results of first principles calculations summarized in Paper II, published as a follow-up paper. The results imply that utmost care is to be taken when dealing with transition metal precipitation during ion implantation into silicon because variations in the dopant content can affect the reproducibility of results even at extremely low dopant concentrations.

  10. Autoimmunity contributes to nociceptive sensitization in a mouse model of complex regional pain syndrome.

    PubMed

    Li, Wen-Wu; Guo, Tian-Zhi; Shi, Xiaoyou; Czirr, Eva; Stan, Trisha; Sahbaie, Peyman; Wyss-Coray, Tony; Kingery, Wade S; Clark, J David

    2014-11-01

    Complex regional pain syndrome (CRPS) is a painful, disabling, chronic condition whose etiology remains poorly understood. The recent suggestion that immunological mechanisms may underlie CRPS provides an entirely novel framework in which to study the condition and consider new approaches to treatment. Using a murine fracture/cast model of CRPS, we studied the effects of B-cell depletion using anti-CD20 antibodies or by performing experiments in genetically B-cell-deficient (μMT) mice. We observed that mice treated with anti-CD20 developed attenuated vascular and nociceptive CRPS-like changes after tibial fracture and 3 weeks of cast immobilization. In mice with established CRPS-like changes, the depletion of CD-20+ cells slowly reversed nociceptive sensitization. Correspondingly, μMT mice, deficient in producing immunoglobulin M (IgM), failed to fully develop CRPS-like changes after fracture and casting. Depletion of CD20+ cells had no detectable effects on nociceptive sensitization in a model of postoperative incisional pain, however. Immunohistochemical experiments showed that CD20+ cells accumulate near the healing fracture but few such cells collect in skin or sciatic nerves. On the other hand, IgM-containing immune complexes were deposited in skin and sciatic nerve after fracture in wild-type, but not in μMT fracture/cast, mice. Additional experiments demonstrated that complement system activation and deposition of membrane attack complexes were partially blocked by anti-CD20+ treatment. Collectively, our results suggest that CD20-positive B cells produce antibodies that ultimately support the CRPS-like changes in the murine fracture/cast model. Therapies directed at reducing B-cell activity may be of use in treating patients with CRPS. PMID:25218828

  11. Autoimmunity contributes to nociceptive sensitization in a mouse model of complex regional pain syndrome

    PubMed Central

    Li, Wen-Wu; Guo, Tian-Zhi; Shi, Xiaoyou; Czirr, Eva; Stan, Trisha; Sahbaie, Peyman; Wyss-Coray, Tony; Kingery, Wade S.; Clark, J. David

    2014-01-01

    Complex regional pain syndrome (CRPS) is a painful, disabling, chronic condition whose etiology remains poorly understood. The recent suggestion that immunological mechanisms may underlie CRPS provides an entirely novel framework in which to study the condition and consider new approaches to treatment. Using a murine fracture/cast model of CRPS, we studied the effects of B-cell depletion using anti-CD20 antibodies or by performing experiments in genetically B-cell-deficient (µMT) mice. We observed that mice treated with anti-CD20 developed attenuated vascular and nociceptive CRPS-like changes after tibial fracture and 3 weeks of cast immobilization. In mice with established CRPS-like changes, the depletion of CD-20+ cells slowly reversed nociceptive sensitization. Correspondingly, µMT mice, deficient in producing immunoglobulin M (IgM), failed to fully develop CRPS-like changes after fracture and casting. Depletion of CD20+ cells had no detectable effects on nociceptive sensitization in a model of postoperative incisional pain, however. Immunohistochemical experiments showed that CD20+ cells accumulate near the healing fracture but few such cells collect in skin or sciatic nerves. On the other hand, IgM-containing immune complexes were deposited in skin and sciatic nerve after fracture in wild-type, but not in µMT fracture/cast, mice. Additional experiments demonstrated that complement system activation and deposition of membrane attack complexes were partially blocked by anti-CD20+ treatment. Collectively, our results suggest that CD20-positive B cells produce antibodies that ultimately support the CRPS-like changes in the murine fracture/cast model. Therapies directed at reducing B-cell activity may be of use in treating patients with CRPS. PMID:25218828

  12. Regional modeling sensitivity experiments for interpreting the UK Winter 2013-2014 extreme rain

    NASA Astrophysics Data System (ADS)

    Omrani, H.; Vautard, R.; Schaller, N.; Allen, M. R.

    2015-12-01

    During the winter 2013/2014, the UK saw heavy rainfalls associated with a succession of storms reaching Southern England causing widespread flooding, power cuts and major disruptions to transport. The January precipitation set a record for several rain gauge stations in Southern England. The aim of this study is to evaluate the contribution of the anthropogenic climate change, represented by a modification of the sea surface temperature (SST) on the January precipitation. For that, we conducted a sensitivity experiment by running a set of 108 four-months simulations using WRF model with 9 different physics and 12 different SST fields; 9 for the factual world and 99 for the counter-factual world. A spectral nudging technique was used here to ensure a same atmospheric circulation patterns for all the simulations. Therefore, only the thermodynamic effect is considered here. The analysis is focused on January precipitation over the southern England. Results show for 0,5°C SST difference over the Northern Atlantic, the precipitation in the factual simulations is between 0,4 and 8% higher than the precipitation in the counter-factual simulations depending on the physic. A validation test shows that this value is closer to 8% for the "best physic" simulation. It also show a strong spatial variability where in some region the precipitation is higher in the counter-factual world compared the factual world. Finally, a backward trajectories were calculated to evaluate the sensitivity of the moisture sources and air mass trajectories to the SST in the factual and the counter-factual world.

  13. Retinal region of polarization sensitivity switches during ontogeny of rainbow trout.

    PubMed

    Sabbah, Shai; Habib-Nayany, Maheen F; Dargaei, Zahra; Hauser, Frances E; Kamermans, Maarten; Hawryshyn, Craig W

    2013-04-24

    Polarization sensitivity (PS) in vertebrate vision is controversial, perhaps because its underlying mechanism has remained obscure. An issue that might have added to the controversy is that rainbow trout (Oncorhynchus mykiss), which have served as the primary model system for polarization-based orientation, lose their ability to orient relative to celestial polarized-light patterns when parr (fry) transform into migratory smolts (juveniles), which would benefit most from polarization-based orientation. Here we addressed two key questions: (1) what is the mechanism underling PS?, and (2) how can the paradoxical loss of PS in trout smolts be reconciled? We assessed PS from optic nerve recordings in parr and smolts and found that the retinal region with enhanced PS shifted from the ventral retina in parr to the dorsal retina in smolts. This adaptation may allow fish to use the most reliable polarization field encountered at each life stage, the celestial polarization field in the shallow-swimming parr and the depth-insensitive underwater polarization field in the deep-swimming smolts. In addition, we assessed spectral sensitivity across the retina and during ontogeny and fit a cascade retinal model to PS data. We found that differential contribution of two cone detectors with orthogonal PS could drive the variation in PS and that feedback from horizontal cells to cones could explain the differential amplification of PS. This elegant arrangement, in which weak PS of cones is amplified and tuned by retinal networks, allows for PS without interfering with sampling of other visual information and illustrates how sensory systems may simultaneously process disparate aspects of physical environments. PMID:23616549

  14. High sensitivity boron quantification in bulk silicon using the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be nuclear reaction

    SciTech Connect

    Moro, Marcos V.; Silva, Tiago F. da; Added, Nemitala; Rizutto, Marcia A.; Tabacniks, Manfredo H.; Neira, John B.; Neto, Joao B. F.

    2013-05-06

    There is a great need to quantify sub-ppm levels of boron in bulk silicon. There are several methods to analyze B in Si: Nuclear Reaction Analysis using the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be reaction exhibits a quantification limit of some hundreds ppm of B in Si. Heavy Ion Elastic Recoil Detection Analysis offers a detection limit of 5 to 10 at. ppm. Secondary Ion Mass Spectrometry is the method of choice of the semiconductor industry for the analysis of B in Si. This work verifies the use of NRA to quantify B in Si, and the corresponding detection limits. Proton beam with 1.6 up to 2.6 MeV was used to obtain the cross-section of the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be nuclear reaction at 170 Degree-Sign scattering angle. The results show good agreementwith literature indicating that the quantification of boron in silicon can be achieved at 100 ppm level (high sensitivity) at LAMFI-IFUSP with about 16% uncertainty. Increasing the detection solid angle and the collected beam charge, can reduce the detection limit to less than 100 ppm meeting present technological needs.

  15. Silicon on-chip side-coupled high-Q micro-cavities for the multiplexing of high sensitivity photonic crystal integrated sensors array

    NASA Astrophysics Data System (ADS)

    Yang, Daquan; Wang, Chunhong; Yuan, Wei; Wang, Bo; Yang, Yujie; Ji, Yuefeng

    2016-09-01

    A novel two-dimensional (2D) silicon (Si) photonic crystal (PC) α-H0-slot micro-cavity with high Q-factor and high sensitivity (S) is presented. Based on the proposed α-H0-Slot micro-cavities, an optimal design of photonic crystal integrated sensors array (PC-ISA) on monolithic silicon on insulator (SOI) is displayed. By using finite-difference time-domain (FDTD) method, the simulation results demonstrate that both large S of 200 nm/RIU (RIU=refractive index unit) and high Q-factor >104 at telecom wavelength range can be achieved simultaneously. And the sensor figure of merit (FOM)>7000 is featured, an order of magnitude improvement over previous 2D PC sensors array. In addition, for the proposed 2D PC-ISA device, each sensor unit is shown to independently shift its resonance wavelength in response to the changes in refractive index (RI) and does not perturb the others. Thus, it is potentially an ideal platform for realizing ultra-compact lab-on-a-chip applications with dense arrays of functionalized spots for multiplexed sensing, and also can be used as an opto-fluidic architecture for performing highly parallel detection of biochemical interactions in aqueous environments.

  16. Electrocatalytic activity of NiO on silicon nanowires with a carbon shell and its application in dye-sensitized solar cell counter electrodes.

    PubMed

    Kim, Junhee; Jung, Cho-long; Kim, Minsoo; Kim, Soomin; Kang, Yoonmook; Lee, Hae-seok; Park, Jeounghee; Jun, Yongseok; Kim, Donghwan

    2016-04-14

    To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the resulting nanomaterial exhibits excellent electrocatalytic activity and performs well as a counter electrode for dye-sensitized solar cells (DSSCs). The compositions of the materials were examined using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. Their micro- and nano-structures were investigated using scanning electron microscopy and transmission electron microscopy. The electrochemical activity toward I(-)/I3(-) was examined using cyclic voltammetry and electrochemical impedance spectroscopy. The obtained peak power conversion efficiency of the DSSC based on the NiO@SiNW/C counter electrode was 9.49%, which was greater than that of the DSSC based on the Pt counter electrode. PMID:27001286

  17. Dust emission parameterization scheme over the MENA region: Sensitivity analysis to soil moisture and soil texture

    NASA Astrophysics Data System (ADS)

    Gherboudj, Imen; Beegum, S. Naseema; Marticorena, Beatrice; Ghedira, Hosni

    2015-10-01

    The mineral dust emissions from arid/semiarid soils were simulated over the MENA (Middle East and North Africa) region using the dust parameterization scheme proposed by Alfaro and Gomes (2001), to quantify the effect of the soil moisture and clay fraction in the emissions. For this purpose, an extensive data set of Soil Moisture and Ocean Salinity soil moisture, European Centre for Medium-Range Weather Forecasting wind speed at 10 m height, Food Agricultural Organization soil texture maps, MODIS (Moderate Resolution Imaging Spectroradiometer) Normalized Difference Vegetation Index, and erodibility of the soil surface were collected for the a period of 3 years, from 2010 to 2013. Though the considered data sets have different temporal and spatial resolution, efforts have been made to make them consistent in time and space. At first, the simulated sandblasting flux over the region were validated qualitatively using MODIS Deep Blue aerosol optical depth and EUMETSAT MSG (Meteosat Seciond Generation) dust product from SEVIRI (Meteosat Spinning Enhanced Visible and Infrared Imager) and quantitatively based on the available ground-based measurements of near-surface particulate mass concentrations (PM10) collected over four stations in the MENA region. Sensitivity analyses were performed to investigate the effect of soil moisture and clay fraction on the emissions flux. The results showed that soil moisture and soil texture have significant roles in the dust emissions over the MENA region, particularly over the Arabian Peninsula. An inversely proportional dependency is observed between the soil moisture and the sandblasting flux, where a steep reduction in flux is observed at low friction velocity and a gradual reduction is observed at high friction velocity. Conversely, a directly proportional dependency is observed between the soil clay fraction and the sandblasting flux where a steep increase in flux is observed at low friction velocity and a gradual increase is

  18. Sensitivity of regional forest carbon budgets to continuous and stochastic climate change pressures

    NASA Astrophysics Data System (ADS)

    Sulman, B. N.; Desai, A. R.; Scheller, R. M.

    2010-12-01

    Climate change is expected to impact forest-atmosphere carbon budgets through three processes: 1. Increased disturbance rates, including fires, mortality due to pest outbreaks, and severe storms 2. Changes in patterns of inter-annual variability, related to increased incidence of severe droughts and defoliating insect outbreaks 3. Continuous changes in forest productivity and respiration, related to increases in mean temperature, growing season length, and CO2 fertilization While the importance of these climate change effects in future regional carbon budgets has been established, quantitative characterization of the relative sensitivity of forested landscapes to these different types of pressures is needed. We present a model- and- data-based approach to understanding the sensitivity of forested landscapes to climate change pressures. Eddy-covariance and biometric measurements from forests in the northern United States were used to constrain two forest landscape models. The first, LandNEP, uses a prescribed functional form for the evolution of net ecosystem productivity (NEP) over the age of a forested grid cell, which is reset following a disturbance event. This model was used for investigating the basic statistical properties of a simple landscape’s responses to climate change pressures. The second model, LANDIS-II, includes different tree species and models forest biomass accumulation and succession, allowing us to investigate the effects of more complex forest processes such as species change and carbon pool accumulation on landscape responses to climate change effects. We tested the sensitivity of forested landscapes to these three types of climate change pressures by applying ensemble perturbations of random disturbance rates, distribution functions of inter-annual variability, and maximum potential carbon uptake rates, in the two models. We find that landscape-scale net carbon exchange responds linearly to continuous changes in potential carbon uptake and

  19. Microbolometer Terahertz Focal Plane Array and Camera with Improved Sensitivity in the Sub-Terahertz Region

    NASA Astrophysics Data System (ADS)

    Oda, Naoki; Kurashina, Seiji; Miyoshi, Masaru; Doi, Kohei; Ishi, Tsutomu; Sudou, Takayuki; Morimoto, Takao; Goto, Hideki; Sasaki, Tokuhito

    2015-10-01

    A pixel in an uncooled microbolometer terahertz (THz) focal plane array (FPA) has a suspended structure above read-out integrated circuit (ROIC) substrate. An optical cavity structure is formed between a thin metallic layer deposited on the suspended structure and a thick metallic layer deposited on the ROIC surface. The geometrical optical cavity length for our previous pixel structure, 3-4 μm, is extended three times, so that responsivity can be increased in the sub-THz region. This modification is carried out by depositing a thick SiN layer on the thick metallic layer. The modified pixel structure is applied to 640 × 480 and 320 × 240 THz-FPAs with 23.5 μm pixel pitch. Minimum detectable powers per pixel (MDP) are evaluated for these FPAs at 4.3, 2.5, 0.6, and 0.5 THz, and the MDP values are found to be improved by a factor of ten at 0.6 and 0.5 THz. The MDP values of the THz-FPAs developed in this work are compared with those of other THz detectors, such as uncooled antenna-coupled CMOS (complimentary metal-oxide semiconductor) THz-FPAs and cooled bolometer arrays. It is found that our THz-FPAs are more sensitive in the sub-THz region than the CMOS THz-FPAs, while they are much less sensitive than the cooled bolometer arrays. These THz-FPAs are incorporated into a 640 × 480 THz camera and 320 × 240 THz camera, and imaging equipment is developed. The equipment consists of a linearly polarized sub-THz source, a collimator lens, a beam homogenizer, two wire grids, a quarter-wave plate, and two THz cameras, and sub-THz images are demonstrated. It should be mentioned for the equipment that imaging of transmission and reflection is realized by moving only the quarter-wave plate, and the reflection image is taken along a direction normal to a sample surface so that the reflection image is hardly deformed.

  20. High-Sensitivity Broadband Spectral Line Surveys of Star Forming Regions with the CSO

    NASA Astrophysics Data System (ADS)

    Weaver, Susanna L. Widicus; Sumner, Matthew C.; Rice, Frank; Zmuidzinas, Jonas; Blake, Geoffrey A.

    2009-06-01

    Spectral line surveys are powerful tools for astrochemistry because they circumvent the one-line-at-a-time approach that has historically hampered new molecule identification. Until recently, line surveys were typically motivated by the need to characterize the major components of interstellar clouds, i.e. the so-called ``interstellar weeds." Previously reported surveys therefore often do not provide the sensitivity levels required for identification of new molecules with weak spectral signatures. The goal of our recent observations with the Caltech Submillimeter Observatory (CSO) is to shift the focus of spectral line surveys away from the interstellar weeds and toward detection of new interstellar molecules. We have obtained broadband, high-sensitivity spectra toward several star forming regions with the new λ=1 mm receiver at the CSO. When used with the facility AOS's, this receiver affords 4 GHz of DSB spectral coverage for each LO setting. We have employed a stepped frequency-offset approach to allow for full spectral deconvolution. The noise temperature of this receiver is ˜100 K (SSB), resulting in spectral RMS levels that far surpass those reported in similar previous studies. Our initial observations targeted the Orion and Sagittarius B2(N-LMH) hot cores and a collection of Class 0 sources. We have now completed our coverage of these initial targets, and upcoming observing time has been allocated for similar surveys of the hot cores W51 e1/e2 and G34.3+0.2. We have fully deconvolved 28 GHz of spectra on Orion with RMS levels of T_A^*˜20 mK. Our coverage on Sgr was more limited, yielding ˜8 GHz of fully-deconvolved spectra to the same RMS level. In this talk, we will report on the data analysis for the Orion and Sgr observations, discuss our progress on line surveys of other star-forming regions, and discuss the implications of these results in the context of recent hot core astrochemical models.

  1. Sensitivity of Model Estimates of Contemporary Global and Regional Sea-Level Changes to Geothermal Flow

    NASA Astrophysics Data System (ADS)

    Piecuch, Christopher; Heimbach, Patrick; Ponte, Rui; Forget, Gael

    2015-04-01

    An ocean general circulation model in a global configuration, constrained to observations over the period 1993-2010 as part of the ECCO (Estimating the Circulation and Climate of the Ocean) project, has been used to to infer the influence of geothermal flow on estimates of contemporary sea level changes. Two distinct simulations are compared, which differ only with regard to whether they apply geothermal flow as a bottom boundary condition. Geothermal flow forcing increases the global mean sea level trend over 1993-2010 by 0.11 mm yr-1 in the perturbation simulation relative to the control simulation with no geothermal forcing, mostly due to increased net thermal expansion in the deep ocean (below 2000 m). The Southern Ocean is particularly sensitive to geothermal flow, with differences between regional sea level trends from the perturbation and control simulations up to ±1 mm yr-1 in some places. More generally, it is suggested that ocean heat transports redistribute the geothermal input along constant pressure surfaces and constant surfaces of temperature or salinity. This redistribution of heat results in stronger (weaker) steric height trend differences between the two solutions over deeper (shallower) areas, and effects anomalous redistribution of ocean mass from deeper to shallower areas in the perturbation solution relative to the control solution. Given the sparsity of heat flow measurements, ocean state estimation could (in principle) be a means to the end of constraining solid Earth heat flow estimates over the global ocean.

  2. Atlas-based segmentation of brainstem regions in neuromelanin-sensitive magnetic resonance images

    NASA Astrophysics Data System (ADS)

    Puigvert, Marc; Castellanos, Gabriel; Uranga, Javier; Abad, Ricardo; Fernández-Seara, María. A.; Pastor, Pau; Pastor, María. A.; Muñoz-Barrutia, Arrate; Ortiz de Solórzano, Carlos

    2015-03-01

    We present a method for the automatic delineation of two neuromelanin rich brainstem structures -substantia nigra pars compacta (SN) and locus coeruleus (LC)- in neuromelanin sensitive magnetic resonance images of the brain. The segmentation method uses a dynamic multi-image reference atlas and a pre-registration atlas selection strategy. To create the atlas, a pool of 35 images of healthy subjects was pair-wise pre-registered and clustered in groups using an affinity propagation approach. Each group of the atlas is represented by a single exemplar image. Each new target image to be segmented is registered to the exemplars of each cluster. Then all the images of the highest performing clusters are enrolled into the final atlas, and the results of the registration with the target image are propagated using a majority voting approach. All registration processes used combined one two-stage affine and one elastic B-spline algorithm, to account for global positioning, region selection and local anatomic differences. In this paper, we present the algorithm, with emphasis in the atlas selection method and the registration scheme. We evaluate the performance of the atlas selection strategy using 35 healthy subjects and 5 Parkinson's disease patients. Then, we quantified the volume and contrast ratio of neuromelanin signal of these structures in 47 normal subjects and 40 Parkinson's disease patients to confirm that this method can detect neuromelanin-containing neurons loss in Parkinson's disease patients and could eventually be used for the early detection of SN and LC damage.

  3. Baffin Island snow extent sensitivity: Insights from a regional climate model

    NASA Astrophysics Data System (ADS)

    Berdahl, Mira; Robock, Alan

    2013-05-01

    Recent modeling efforts suggest that the Little Ice Age (LIA) onset could be explained by a series of four large decadally-spaced volcanic eruptions. At that time, glaciers on Baffin Island advanced and did not retreat until the past century, perhaps due to Arctic and North Atlantic Ocean sea ice feedbacks. To try to determine what parameters sustain snow cover, we investigate the relative impacts of changes in radiation and advection on minimum summer snow extent over Baffin Island. We used the Weather Research and Forecasting (WRF) model to run eight 6 month long (April-September), 10 km resolution simulations, in which we varied boundary condition temperatures, solar radiation, and sea ice cover. Although the Control Run underestimated cloud cover and thus produced an exaggerated diurnal 2 m temperature cycle, the relative changes of snow extent show that WRF accurately simulates snow expansion into the same regions as during the LIA. With an average temperature decrease from current temperatures by -3.9 ± 1.1 K, it only requires one season for the model to lower the snowline by comparable elevation changes seen during the descent into the LIA. WRF's maximum snow line sensitivity is 7 K/km, within the range of the typically assumed lapse rate of 5-7 K/km in the Canadian Arctic. Thus, if a shift in the Arctic climate greatly expanded sea ice coverage following large volcanic eruptions, this would have been enough to perpetuate an ice sheet on Baffin Island throughout the LIA.

  4. Phase-Sensitive Reflective Imaging Device in the mm-wave and Terahertz Regions

    NASA Astrophysics Data System (ADS)

    Gallerano, Gian Piero; Doria, Andrea; Germini, Marzia; Giovenale, Emilio; Messina, Giovanni; Spassovsky, Ivan P.

    2009-12-01

    Two Free Electron Laser sources have been developed at ENEA-Frascati for a variety of applications: A Compact Free Electron Laser (C-FEL) that provides coherent radiation in the frequency range between 90 and 150 GHz Gallerano et al. (Infrared Phys. and Techn. 40:161, 1999), and a second source, FEL-CATS, which utilizes a peculiar radio-frequency structure to generate coherent emission in the range 0.4 to 0.7 THz Doria et al. (Phys. Rev. Lett 93:264801, 2004). The high peak power of several kW in 15 to 50 ps pulses, makes these sources particularly suitable for the assessment of exposure limits in biological systems and for long range detection. In this paper we present a phase-sensitive reflective imaging device in the mm-wave and THz regions, which has proven to be a valuable tool in the biological Ramundo-Orlando et al. (Bioelectromagnetics 28:587-598, 2007), environmental Doria et al. (2005) and art conservation fields Gallerano et al. (2008). Different setups have been tested at different levels of spatial resolution to image objects from a few centimeter square to larger sizes. Images have been compared to identify and characterize the contrast mechanism.

  5. Fabrication of detectors and transistors on high-resistivity silicon

    SciTech Connect

    Holland, S.

    1988-06-01

    A new process for the fabrication of silicon p-i-n diode radiation detectors is described. The utilization of backside gettering in the fabrication process results in the actual physical removal of detrimental impurities from critical device regions. This reduces the sensitivity of detector properties to processing variables while yielding low diode reverse-leakage currents. In addition, gettering permits the use of processing temperatures compatible with integrated-circuit fabrication. P-channel MOSFETs and silicon p-i-n diodes have been fabricated simultaneously on 10 k..cap omega../center dot/cm<100> silicon using conventional integrated-circuit processing techniques. 25 refs., 5 figs.

  6. Detection of critical LUCC indices and sensitive watershed regions related to lake algal blooms: a case study of Taihu Lake.

    PubMed

    Lin, Chen; Ma, Ronghua; Su, Zhihu; Zhu, Qing

    2015-02-01

    Taihu Lake in China has suffered from severe eutrophication over the past 20 years which is partly due to significant land use/cover change (LUCC). There is an increasing need to detect the critical watershed region that significantly affects lake water degradation, which has great significance for environmental protection. However, previous studies have obtained conflicting results because of non-uniform lake indicators and inadequate time periods. To identify the sensitive LUCC indices and buffer distance regions, three lake divisions (Meiliang Lake, Zhushan Lake and Western Coastal region) and their watershed region within the Taihu Lake basin were chosen as study sites, the algal area was used as a uniform lake quality indicator and modeled with LUCC indices over the whole time series. Results showed that wetland (WL) and landscape index such as Shannon diversity index (SHDI) appeared to be sensitive LUCC indices when the buffer distance was less than 5 km, while agricultural land (AL) and landscape fragmentation (Ci) gradually became sensitive indices as buffer distances increased to more than 5 km. For the relationship between LUCC and lake algal area, LUCC of the WC region seems to have no significant effect on lake water quality. Conversely, LUCC within ML and ZS region influenced algal area of corresponding lake divisions greatly, while the most sensitive regions were found in 3 km to 5 km, rather than the whole catchment. These results will be beneficial for the further understanding of the relationship between LUCC and lake water quality, and will provide a practical basis for the identification of critical regions for lake. PMID:25642691

  7. Detection of Critical LUCC Indices and Sensitive Watershed Regions Related to Lake Algal Blooms: A Case Study of Taihu Lake

    PubMed Central

    Lin, Chen; Ma, Ronghua; Su, Zhihu; Zhu, Qing

    2015-01-01

    Taihu Lake in China has suffered from severe eutrophication over the past 20 years which is partly due to significant land use/cover change (LUCC). There is an increasing need to detect the critical watershed region that significantly affects lake water degradation, which has great significance for environmental protection. However, previous studies have obtained conflicting results because of non–uniform lake indicators and inadequate time periods. To identify the sensitive LUCC indices and buffer distance regions, three lake divisions (Meiliang Lake, Zhushan Lake and Western Coastal region) and their watershed region within the Taihu Lake basin were chosen as study sites, the algal area was used as a uniform lake quality indicator and modeled with LUCC indices over the whole time series. Results showed that wetland (WL) and landscape index such as Shannon diversity index (SHDI) appeared to be sensitive LUCC indices when the buffer distance was less than 5 km, while agricultural land (AL) and landscape fragmentation (Ci) gradually became sensitive indices as buffer distances increased to more than 5 km. For the relationship between LUCC and lake algal area, LUCC of the WC region seems to have no significant effect on lake water quality. Conversely, LUCC within ML and ZS region influenced algal area of corresponding lake divisions greatly, while the most sensitive regions were found in 3 km to 5 km, rather than the whole catchment. These results will be beneficial for the further understanding of the relationship between LUCC and lake water quality, and will provide a practical basis for the identification of critical regions for lake. PMID:25642691

  8. High efficiency antireflection coating in MWIR region (3.6-4.9 μm) simultaneously effective for Germanium and Silicon optics

    NASA Astrophysics Data System (ADS)

    Bhatt, Meenakshi; Nautiyal, B. B.; Bandyopadhyay, P. K.

    2010-01-01

    Antireflection coatings have critical importance in thermal imaging system working in MWIR region (3-5 μm) since optics of high refractive index materials are used. Germanium (Ge) and Silicon (Si) optics are used extensively in the MWIR thermal systems. In this paper a study has been carried out on the design and fabrication of multi-substrate antireflection coating effective for Germanium and Silicon optics in MWIR (3.6-4.9 μm) region. The wave band 3.6-4.9 μm is chosen for the reported work because detector system used in MWIR region has a band selection filter effective in the same wavelength region and atmospheric transmission window in MWIR region is effective in 3-5 μm spectral band. Comprehensive search method was used to design the multilayer stack on the substrate. The coating materials used in the design were Germanium (Ge), Hafnium oxide (HfO 2) and Y-Ba-Fluoride (IR-F625). The fabrication of coating was made in a coating plant fitted with Cryo pump system and residual gas analyzer (RGA). The evaporation was carried out at high vacuum (2-6 × 10 -6 mbar) with the help of electron beam gun system and layer thicknesses were measured with crystal monitor. The result achieved for the antireflection coating was 98.5% average transmission in 3.6-4.9 μm band for Germanium and Silicon optics. This work will be helpful in reducing the plant operation time, material and power consumption, as two different kinds of optics are simultaneously coated in a single coating cycle.

  9. Tetrodotoxin-sensitive calcium-conducting channels in the rat hippocampal CA1 region.

    PubMed Central

    Akaike, N; Takahashi, K

    1992-01-01

    1. Tetrodotoxin (TTX)-sensitive Ca2+ conducting channels which produce a transient inward current were investigated in pyramidal neurones freshly dissociated from the dorsal part of rat hippocampal CA1 region by the use of the suction-pipette technique, which allows for intracellular perfusion under a single-electrode voltage clamp. 2. In all cells superfused with Na(+)- and K(+)-free external solution containing 10 mM-Ca2+ and 10(-5) M-La3+, a transient inward Ca2+ current was evoked by a step depolarization to potentials more positive than about -50 mV from a holding potential (VH) of -100 mV. This current was inhibited by either removing the extracellular Ca2+ or adding TTX (termed as 'TTX-ICa'). 3. Activation and inactivation processes of the TTX-ICa were highly potential dependent at 20-22 degrees C, and the latter was fitted by a double exponential function. The time to peak of the current decreased from 5.0 to 2.3 ms at a test potential change from -50 to 0 mV. The time constants of the current decay decreased from 2.8 to 2.2 ms for fast component (tau if) and from 16.0 to 8.2 ms for slow component (tau is) at a potential change from -35 to -10 mV. 4. The TTX-ICa was activated at threshold potential of about -55 mV and reached full activation at -30 mV. The steady-state inactivation of TTX-ICa could be fitted by a Boltzmann equation with a slope factor of 6.0 mV and a half-inactivation voltage of -72.5 mV. 5. Biphasic recovery (reactivation) from the complete inactivation of TTX-ICa was observed. The time constant of the major component (78.8 to 91.6% of total) of the reactivation was 13.1 ms, and that of the minor one was 120 to 240 ms. Therefore, TTX-ICa remained fairly constant at a train of stimulation up to 3 Hz. However, the inhibition of current amplitude occurred as the repetitive stimulation increased more than 10 Hz, and considerable tonic inhibition occurred with increasing stimulation frequency. 6. When the peak amplitudes in the individual

  10. Effect of Different Degrees of Sensitization on the EIS Response of 316L and 316 SS in Transpassive Region

    NASA Astrophysics Data System (ADS)

    Morshed Behbahani, K.; Pakshir, M.

    2014-06-01

    Different heat treatments were conducted on 316L and 316 stainless steels, and the sensitized specimens were characterized using anodic polarization and EIS tests in 0.5 M H2SO4 containing 0.01 molar KSCN. The potential ranges related to the transpassive region related to each specimen were determined. The EIS experiments were conducted at different potentials in that region, and the results showed the presence of three different regions, namely the anodic dissolution of the passive layer, dissolution of the grain boundaries, and the occurrence of pitting corrosion owing to the variations in the anodic potential. The higher the applied sensitization temperature, the lower the obtained charge-transfer resistance ( R ct) values, but healing effect was observed at the temperatures above 600 °C for these alloys.

  11. Sensitivity of Air-sea Exchange In A Regional Scale Coupled Ice/ocean/atmosphere Model

    NASA Astrophysics Data System (ADS)

    Schrum, C.; Hübner, U.; Jacob, D.; Podzun, R.

    The sub-systems ice, ocean and atmosphere are coupled on the global as well as the regional scale. However, regional coupled modeling is only in the beginning, full cou- pled models which are able to describe the interaction on the regional scale and the feedback mechanism are rare at the moment. For the North Sea and the Baltic Sea such a coupled model has been developed and exemplary integrated over a full seasonal cy- cle. By comparison of different regionalization studies the impact of the regional at- mospheric modeling and coupling on the air sea fluxes have been investigated. It was shown that the regionalization as well as the coupling show strong influence on the air/sea fluxes and thus on the oceanic conditions. Further problems in regional mod- eling like the description of storm track variability and its influence on the regional ocean model were identified.

  12. Magnetic-based Fano resonance of hybrid silicon-gold nanocavities in the near-infrared region.

    PubMed

    Ci, Xuting; Wu, Botao; Liu, Yan; Chen, Gengxu; Wu, E; Zeng, Heping

    2014-10-01

    Direct interference between the orthogonal electric and magnetic modes in a hybrid silicon-gold nanocavity is demonstrated to induce a pronounced asymmetric magnetic-based Fano resonance in the total scattering spectrum at near-infrared frequencies. Differing from the previously reported magnetic-based Fano resonances in metal nanoparticle clusters, the narrow discrete mode provided by the silicon magnetic dipole resonance can be directly excited by external illumination, and greatly enhanced electric and magnetic fields are simultaneously obtained at the Fano dip. PMID:25321953

  13. Stem-loop DNA-assisted silicon nanowires-based biochemical sensors with ultra-high sensitivity, specificity, and multiplexing capability

    NASA Astrophysics Data System (ADS)

    Xie, Juan; Jiang, Xiangxu; Zhong, Yiling; Lu, Yimei; Wang, Siyi; Wei, Xinpan; Su, Yuanyuan; He, Yao

    2014-07-01

    A class of stem-loop DNA-assisted silicon nanowires (SiNWs)-based fluorescent biosensor is presented in this report. Significantly, the sensor enables rapid and sensitive detection of DNA targets with a concentration as low as 1 pM. Moreover, the large planar surface of SiNWs facilitates simultaneous assembly with different DNA strands, which is favorable for multiplexed DNA detection. On the other hand, the SiNWs-based sensor is highly efficacious for detecting heavy metal ions. Mercury ions (Hg2+) of low concentrations (e.g., 5 pM) are readily identified from its mixture with over 10 kinds of interfering metal ions, even in real water samples. Given that SiNWs can be fabricated in a facile, reproducible and low-cost manner, this kind of SiNWs-based high-performance sensor is expected to be a practical analytical tool for a variety of biological and environment-protection applications.A class of stem-loop DNA-assisted silicon nanowires (SiNWs)-based fluorescent biosensor is presented in this report. Significantly, the sensor enables rapid and sensitive detection of DNA targets with a concentration as low as 1 pM. Moreover, the large planar surface of SiNWs facilitates simultaneous assembly with different DNA strands, which is favorable for multiplexed DNA detection. On the other hand, the SiNWs-based sensor is highly efficacious for detecting heavy metal ions. Mercury ions (Hg2+) of low concentrations (e.g., 5 pM) are readily identified from its mixture with over 10 kinds of interfering metal ions, even in real water samples. Given that SiNWs can be fabricated in a facile, reproducible and low-cost manner, this kind of SiNWs-based high-performance sensor is expected to be a practical analytical tool for a variety of biological and environment-protection applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01097c

  14. Effect of prism index on sensitivity of lossy mode resonance sensors operating in visible region

    NASA Astrophysics Data System (ADS)

    Kaur, Davinder; Sharma, Vinod K.; Kapoor, Avinashi

    2015-01-01

    We present the theoretical results of the optimization of lossy mode resonance sensors at visible wavelengths. Both angular and spectral interrogations are carried out for absorbing indium tin oxide (ITO) films placed on glass prism. The inclusion of a low-index layer between the prism and the lossy (ITO) layer can produce an efficient refractive index sensor for bio/chemical applications. Further increase in sensitivity can be achieved by changing the index of the prism. It is shown that the sensitivity has strong dependence on the index of prism. Sensitivities as high as 4670 nm/RIU for spectral mode and 67 deg/RIU for angular mode with small values of full width at half maximum (FWHM) can be achieved. Dependence of sensitivity and FWHM on refractive index and thickness of low-index matching layer is also investigated.

  15. REGIONAL ASSESSMENT OF AQUIFER VULNERABILITY AND SENSITIVITY IN THE CONTERMINOUS UNITED STATES

    EPA Science Inventory

    This report provides, in a generalized, largely graphic format, are presentation of ground-water vulnerability, precipitation distribution, population density, potential well yield, and aquifer sensitivity for each of the 48 conterminous states. lassification scheme is developed ...

  16. REGIONAL ASSESSMENT OF AQUIFER VULNERABILITY AND SENSITIVITY IN THE CONTERMINOUS UNITED STATES

    EPA Science Inventory

    This report provides, in a generalized, largely graphic format, are presentation of ground-water vulnerability, precipitation distribution, population density, potential well yield, and aquifer sensitivity for each of the 48 conterminous states. Classification scheme is developed...

  17. The sensitivity of regional transpiration to land-surface characteristics: Significance of feedback

    SciTech Connect

    Jacobs, C.M.J.; De Bruin, H.A.R. )

    1992-07-01

    Several authors have determined the sensitivity of transpiration to different environmental parameters using the Penman-Monteith equation. In their studies, the interaction between transpiration and, for example, the humidity of the air is ignored: the feedback with the planetary boundary layer (PBL) is not accounted for. Furthermore, surface-layer (SL) feedback (e.g., stability effects in the surface layer) is often neglected. In our study, both PBL feedback and SL feedback are accounted for by coupling the big-leaf model to a detailed model for the PBL. This study provides an analysis of the sensitivity of transpiration to net radiation calculated after an albedo change, aerodynamic resistance calculated after a change in the aerodynamic roughness, and surface resistance. It is shown that PBL feedback affects the sensitivity of transpiration to the tested variables significantly. The sensitivity of transpiration to surface resistance and to aerodynamic resistance, or aerodynamic roughness, is decreased by the PBL feedback. In contrast, PBL feedback enlarges the sensitivity of transpiration to the net radiation, or albeds, and appears to be highly dependent on the specific conditions, especially on the aerodynamic roughness of the vegetation. It is recommended that future sensitivity studies for prognostic use account for PBL feedback.

  18. Fine structure marker rescue of temperature-sensitive mutations of vaccinia virus within a central conserved region of the genome.

    PubMed Central

    Ensinger, M J; Weir, J P; Moss, B

    1985-01-01

    Fine structure marker rescue involving the use of subfragments of vaccinia virus HindIII DNA fragments L, J, and H has been used to map the mutations in eight temperature-sensitive mutants of vaccinia virus representing four complementation groups. Comparison of their map locations with the positions of the open reading frames and RNA transcripts that have been mapped within this region has allowed the identification of one or two polypeptides as the temperature-sensitive gene product of each mutant. PMID:4068140

  19. The most sensitive inputs to cutaneous representing regions of primary somatosensory cortex do not change with behavioral training.

    PubMed

    Blake, David T; Spingath, Elsie

    2015-12-01

    Learning a sensory detection task leads to an increased primary sensory cortex response to the detected stimulus, while learning a sensory discrimination task additionally leads to a decreased sensory cortex response to the distractor stimulus. Neural responses are scaled up, and down, in strength, along with concomitant changes in receptive field size. The present work considers neural response properties that are invariant to learning. Data are drawn from two animals that were trained to detect and discriminate spatially separate taps delivered to positions on the skin of their fingers. Each animal was implanted with electrodes positioned in area 3b, and responses were derived on a near daily basis over 84 days in animal 1 and 202 days in animal 2. Responses to taps delivered in the receptive field were quantitatively measured each day, and receptive fields were audiomanually mapped each day. In the subset of responses that had light cutaneous receptive fields, a preponderance of the days, the most sensitive region of the field was invariant to training. This skin region was present in the receptive field on all, or nearly all, occasions in which the receptive field was mapped, and this region constituted roughly half of the most sensitive region. These results suggest that maintaining the most sensitive inputs as dominant in cortical receptive fields provide a measure of stability that may be transformationally useful for minimizing reconstruction errors and perceptual constancy. PMID:26634900

  20. High regional climate sensitivity over continental China constrained by glacial-recent changes in temperature and the hydrological cycle

    PubMed Central

    Eagle, Robert A.; Risi, Camille; Mitchell, Jonathan L.; Eiler, John M.; Seibt, Ulrike; Neelin, J. David; Li, Gaojun; Tripati, Aradhna K.

    2013-01-01

    The East Asian monsoon is one of Earth’s most significant climatic phenomena, and numerous paleoclimate archives have revealed that it exhibits variations on orbital and suborbital time scales. Quantitative constraints on the climate changes associated with these past variations are limited, yet are needed to constrain sensitivity of the region to changes in greenhouse gas levels. Here, we show central China is a region that experienced a much larger temperature change since the Last Glacial Maximum than typically simulated by climate models. We applied clumped isotope thermometry to carbonates from the central Chinese Loess Plateau to reconstruct temperature and water isotope shifts from the Last Glacial Maximum to present. We find a summertime temperature change of 6–7 °C that is reproduced by climate model simulations presented here. Proxy data reveal evidence for a shift to lighter isotopic composition of meteoric waters in glacial times, which is also captured by our model. Analysis of model outputs suggests that glacial cooling over continental China is significantly amplified by the influence of stationary waves, which, in turn, are enhanced by continental ice sheets. These results not only support high regional climate sensitivity in Central China but highlight the fundamental role of planetary-scale atmospheric dynamics in the sensitivity of regional climates to continental glaciation, changing greenhouse gas levels, and insolation. PMID:23671087

  1. The Silicon Pixel Detector for ALICE Experiment

    SciTech Connect

    Fabris, D.; Bombonati, C.; Dima, R.; Lunardon, M.; Moretto, S.; Pepato, A.; Bohus, L. Sajo; Scarlassara, F.; Segato, G.; Shen, D.; Turrisi, R.; Viesti, G.; Anelli, G.; Boccardi, A.; Burns, M.; Campbell, M.; Ceresa, S.; Conrad, J.; Kluge, A.; Kral, M.

    2007-10-26

    The Inner Tracking System (ITS) of the ALICE experiment is made of position sensitive detectors which have to operate in a region where the track density may be as high as 50 tracks/cm{sup 2}. To handle such densities detectors with high precision and granularity are mandatory. The Silicon Pixel Detector (SPD), the innermost part of the ITS, has been designed to provide tracking information close to primary interaction point. The assembly of the entire SPD has been completed.

  2. ZnO nanorod/porous silicon nanowire hybrid structures as highly-sensitive NO2 gas sensors at room temperature.

    PubMed

    Liao, Jiecui; Li, Zhengcao; Wang, Guojing; Chen, Chienhua; Lv, Shasha; Li, Mingyang

    2016-02-01

    ZnO nanorod/porous silicon nanowire (ZnO/PSiNW) hybrids with three different structures as highly sensitive NO2 gas sensors were obtained. PSiNWs were first synthesized by metal-assisted chemical etching, and then seeded in three different ways. After that ZnO nanorods were grown on the seeded surface of PSiNWs using a hydrothermal procedure. ZnO/PSiNW hybrids showed excellent gas sensing performance for various NO2 concentrations (5-50 ppm) at room temperature, and the electrical resistance change rate reached as high as 35.1% when responding to 50 ppm NO2. The distinct enhancement was mainly attributed to the faster carrier transportation after combination, the increase in gas sensing areas and the oxygen vacancy (VO) concentration. Moreover, the p-type gas sensing behavior was explained by the gas sensing mechanism and the effect of VO concentration on gas sensing properties was also discussed concerning the photoluminescence (PL) spectra performance. PMID:26804157

  3. Stem-loop DNA-assisted silicon nanowires-based biochemical sensors with ultra-high sensitivity, specificity, and multiplexing capability.

    PubMed

    Xie, Juan; Jiang, Xiangxu; Zhong, Yiling; Lu, Yimei; Wang, Siyi; Wei, Xinpan; Su, Yuanyuan; He, Yao

    2014-08-01

    A class of stem-loop DNA-assisted silicon nanowires (SiNWs)-based fluorescent biosensor is presented in this report. Significantly, the sensor enables rapid and sensitive detection of DNA targets with a concentration as low as 1 pM. Moreover, the large planar surface of SiNWs facilitates simultaneous assembly with different DNA strands, which is favorable for multiplexed DNA detection. On the other hand, the SiNWs-based sensor is highly efficacious for detecting heavy metal ions. Mercury ions (Hg(2+)) of low concentrations (e.g., 5 pM) are readily identified from its mixture with over 10 kinds of interfering metal ions, even in real water samples. Given that SiNWs can be fabricated in a facile, reproducible and low-cost manner, this kind of SiNWs-based high-performance sensor is expected to be a practical analytical tool for a variety of biological and environment-protection applications. PMID:24981573

  4. SENSITIVITY ANALYSIS OF RELMAP (REGIONAL LAGRANGIAN MODEL OF AIR POLLUTION) INVOLVING FINE AND COARSE PARTICULATE MATTER

    EPA Science Inventory

    The REgional Lagrangian Model of air pollution (RELMAP) is a mass-conserving, regional scale, Lagrangian model that simulates ambient concentrations as well as wet and dry deposition of SO2, SO4(2-), and more recently fine (diameters<2.5 micrometers) and coarse (2.5 < diameter < ...

  5. Eddy Fluxes and Sensitivity of the Water Cycle to Spatial Resolution in Idealized Regional Aquaplanet Model Simulations

    SciTech Connect

    Hagos, Samson M.; Leung, Lai-Yung R.; Gustafson, William I.; Singh, Balwinder

    2014-02-28

    A multi-scale moisture budget analysis is used to identify the mechanisms responsible for the sensitivity of the water cycle to spatial resolution using idealized regional aquaplanet simulations. In the higher resolution simulations, moisture transport by eddies fluxes dry the boundary layer enhancing evaporation and precipitation. This effect of eddies, which is underestimated by the physics parameterizations in the low-resolution simulations, is found to be responsible for the sensitivity of the water cycle both directly, and through its upscale effect, on the mean circulation. Correlations among moisture transport by eddies at adjacent ranges of scales provides the potential for reducing this sensitivity by representing the unresolved eddies by their marginally resolved counterparts.

  6. Sensitivity of systematic biases in South Asian summer monsoon simulations to regional climate model domain size and implications for downscaled regional process studies

    NASA Astrophysics Data System (ADS)

    Karmacharya, J.; Levine, R. C.; Jones, R.; Moufouma-Okia, W.; New, M.

    2015-07-01

    Global climate models (GCMs) have good skill in simulating climate at the global scale yet they show significant systematic errors at regional scale. For example, many GCMs exhibit significant biases in South Asian summer monsoon (SASM) simulations. Those errors not only limit application of such GCM output in driving regional climate models (RCMs) over these regions but also raise questions on the usefulness of RCMs derived from those GCMs. We focus on process studies where the RCM is driven by realistic lateral boundary conditions from atmospheric re-analysis which prevents remote systematic errors from influencing the regional simulation. In this context it is pertinent to investigate whether RCMs also suffer from similar errors when run over regions where their parent models show large systematic errors. Furthermore, the general sensitivity of the RCM simulation to domain size is informative in understanding remote drivers of systematic errors in the GCM and in choosing a suitable RCM domain that minimizes those errors. We investigate Met Office Unified Model systematic errors in SASM by comparing global and regional model simulations with targeted changes to the domain and forced with atmospheric re-analysis. We show that excluding remote drivers of systematic errors from the direct area of interest allows the application of RCMs for process studies of the SASM, despite the large errors in the parent global model. The findings in this study are also relevant to other models, many of which suffer from a similar pattern of systematic errors in global model simulations of the SASM.

  7. Evaluating fungicide sensitivity of regional Blumeria graminis f.sp. tritici populations in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blumeria graminis f.sp. tritici (Bgt), cause of wheat powdery mildew, has a high likelihood of developing fungicide resistance because of the large quantity of spores produced along with the mixed mode of reproduction. Additionally, once reduced sensitivity appears in a population it can influence n...

  8. Examining the Sensitivity of Regional Scale Cloud Properties to Convective Microphysics

    NASA Astrophysics Data System (ADS)

    Storer, R. L.; Zhang, G. J.; Song, X.

    2014-12-01

    A two-moment microphysics scheme for deep convection was implemented in the NCAR Community Atmosphere Model version 5 (CAM5) by Song et al. (2012). The new scheme improved hydrometeor profiles in deep convective clouds and increased deep convective detrainment, reducing the negative biases in low and mid-level cloud fraction and liquid water path compared to observations. Here, we examine in more detail the impacts of this improved microphysical representation on regional scale water and radiation budgets. As the primary source of cloud water for stratus clouds is detrainment from deep and shallow convection, the enhanced convective activity leads to larger stratus cloud fractions, higher cloud water content, and more stratiform precipitation in all oceanic regions examined, particularly in the subtropics. This can be seen also in increased values of net cloud radiative forcing. Over land regions, cloud amounts are reduced, leading to weaker cloud forcing and increased OLR. The magnitude and, occasionally, the sign of the changes in cloud properties can differ if scaled by the precipitation produced in a region, and much of the changes occur in the mixed phase region of the atmosphere. This indicates that the complex interactions between liquid and ice phase microphysics can effect changes in regional scale circulations. We will present details of the large scale water and radiation budgets and the microphysical budgets of cloud liquid and ice for several regions. Results will be compared to cloud resolving model simulations.

  9. The LHCb silicon tracker: running experience

    NASA Astrophysics Data System (ADS)

    Saornil Gamarra, S.

    2013-02-01

    The LHCb Silicon Tracker is part of the main tracking system of the LHCb detector at the LHC. It measures very precisely the particle trajectories coming from the interaction point in the region of high occupancies around the beam axis. It covers the full acceptance angle in front of the dipole magnet in the Tracker Turicensis station and the innermost part around the beam axis in the three Inner Tracker stations downstream of the magnet. The Silicon Tracker covers a sensitive area of 12 m2 using silicon micro-strip sensors with very long readout strips. We report on running experience for the experiment. Focussing on electronic and hardware issues we describe some of the lessons learned and pitfalls encountered after three years of successful operation.

  10. Silicone metalization

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2006-12-05

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  11. Silicone metalization

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2008-12-09

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  12. Understanding hydrologic sensitivity and land-atmosphere interactions through remote sensing and high resolution regional model

    NASA Astrophysics Data System (ADS)

    Kumar, Anil

    2016-05-01

    In this study we investigated the impact of land surface surface process & land-atmospheric interaction on weather and surface hydrology. The ultimate goal is to integrate remote sense data into numerical mesoscale weather prediction and regional climate model in order to improve prediction of the impacts of land-atmosphere interactions and land-surface processes on regional weather, and hydrology. We have used climatology based green vegetation fraction and 8-day Moderate Resolution Imaging Spectroradiometer (MODIS) based green vegetation fraction and integrated in the Land Information System to conduct uncoupled simulation to understand the impact on surface and hydrological parameters in the summer season. The vegetation response is also realized through coupled regional climate simulation in which climatological based greenness and 8-days varying vegetation is investigated and quantify the impact of vegetation on summertime precipitation process. This study has bought following findings (a) Satellite based vegetation indices captures vegetation temporal patterns more realistic than climatological vegetation data and detects early/late spring signature through vegetation indices, (b) Integrated satellite vegetation greenness input data in regional weather model resolved much better soil moisture and soil temperature including the diurnal cycle of surface heat fluxes and surface temperature in the simulation. Secondly, integration of the TRMM based satellite rainfall product into coupled hydrological and Atmospheric model and results shows better resolved soil moisture patterns in the remote regions of the Asia Mountain regions.

  13. Microtextured Silicon Surfaces for Detectors, Sensors & Photovoltaics

    SciTech Connect

    Carey, JE; Mazur, E

    2005-05-19

    With support from this award we studied a novel silicon microtexturing process and its application in silicon-based infrared photodetectors. By irradiating the surface of a silicon wafer with intense femtosecond laser pulses in the presence of certain gases or liquids, the originally shiny, flat surface is transformed into a dark array of microstructures. The resulting microtextured surface has near-unity absorption from near-ultraviolet to infrared wavelengths well below the band gap. The high, broad absorption of microtextured silicon could enable the production of silicon-based photodiodes for use as inexpensive, room-temperature multi-spectral photodetectors. Such detectors would find use in numerous applications including environmental sensors, solar energy, and infrared imaging. The goals of this study were to learn about microtextured surfaces and then develop and test prototype silicon detectors for the visible and infrared. We were extremely successful in achieving our goals. During the first two years of this award, we learned a great deal about how microtextured surfaces form and what leads to their remarkable optical properties. We used this knowledge to build prototype detectors with high sensitivity in both the visible and in the near-infrared. We obtained room-temperature responsivities as high as 100 A/W at 1064 nm, two orders of magnitude higher than standard silicon photodiodes. For wavelengths below the band gap, we obtained responsivities as high as 50 mA/W at 1330 nm and 35 mA/W at 1550 nm, close to the responsivity of InGaAs photodiodes and five orders of magnitude higher than silicon devices in this wavelength region.

  14. Reduced sensitivity to contrast signals from the eye region in developmental prosopagnosia.

    PubMed

    Fisher, Katie; Towler, John; Eimer, Martin

    2016-08-01

    Contrast-related signals from the eye region are known to be important for the processing of facial identity. Individuals with developmental prosopagnosia (DP) have severe face recognition problems, which may be linked to deficits in the perceptual processing of identity-related information from the eyes. We tested this hypothesis by measuring N170 components in DP participants and age-matched controls in response to face images where the contrast polarity of the eyes and of other face parts was independently manipulated. In different trials, participants fixated either the eye region or the lower part of a face. In the Control group, contrast-reversal of the eyes resulted in enhanced and delayed N170 components, irrespective of the contrast of other face parts and of gaze location. In the DP group, these effects of eye contrast on N170 amplitudes were strongly and significantly reduced, demonstrating that perceptual face processing in DP is less well tuned to contrast information from the eye region. Inverting the contrast of other parts of the face affected N170 amplitudes only when fixation was outside the eye region. This effect did not differ between the two groups, indicating that DPs are not generally insensitive to the contrast polarity of face images. These results provide new evidence that a selective deficit in detecting and analysing identity-related information provided by contrast signals from the eye region may contribute to the face recognition impairment in DP. PMID:27179151

  15. Immunodominant regions for T helper-cell sensitization on the human nicotinic receptor alpha subunit in myasthenia gravis.

    PubMed Central

    Protti, M P; Manfredi, A A; Straub, C; Howard, J F; Conti-Tronconi, B M

    1990-01-01

    In myasthenia gravis an autoimmune response against the nicotinic acetylcholine receptor (AChR) occurs. The alpha subunit of the AChR contains both the epitope(s) that dominates the antibody response (main immunogenic region) and epitopes involved in T helper cell sensitization. In this study, overlapping synthetic peptides corresponding to the complete AChR alpha-subunit sequence were used to propagate polyclonal AChR-specific T helper cell lines from four myasthenic patients of different HLA types. Response of the T helper lines to the individual peptides was studied. Four immunodominant sequence segments were identified--i.e., residues 48-67, 101-120, 304-322, and 419-437. These regions did not include residues known to form the main immunogenic region or the cholinergic binding site, and they frequently contained sequence motifs that have been proposed to be related to T-epitope formation. Images PMID:2145582

  16. Future changes in regional precipitation simulated by a half-degree coupled climate model: Sensitivity to horizontal resolution

    DOE PAGESBeta

    Shields, Christine A.; Kiehl, Jeffrey T.; Meehl, Gerald A.

    2016-06-02

    The global fully coupled half-degree Community Climate System Model Version 4 (CCSM4) was integrated for a suite of climate change ensemble simulations including five historical runs, five Representative Concentration Pathway 8.5 [RCP8.5) runs, and a long Pre-Industrial control run. This study focuses on precipitation at regional scales and its sensitivity to horizontal resolution. The half-degree historical CCSM4 simulations are compared to observations, where relevant, and to the standard 1° CCSM4. Both the halfdegree and 1° resolutions are coupled to a nominal 1° ocean. North American and South Asian/Indian monsoon regimes are highlighted because these regimes demonstrate improvements due to highermore » resolution, primarily because of better-resolved topography. Agriculturally sensitive areas are analyzed and include Southwest, Central, and Southeast U.S., Southern Europe, and Australia. Both mean and extreme precipitation is discussed for convective and large-scale precipitation processes. Convective precipitation tends to decrease with increasing resolution and large-scale precipitation tends to increase. Improvements for the half-degree agricultural regions can be found for mean and extreme precipitation in the Southeast U.S., Southern Europe, and Australian regions. Climate change responses differ between the model resolutions for the U.S. Southwest/Central regions and are seasonally dependent in the Southeast and Australian regions. Both resolutions project a clear drying signal across Southern Europe due to increased greenhouse warming. As a result, differences between resolutions tied to the representation of convective and large-scale precipitation play an important role in the character of the climate change and depend on regional influences.« less

  17. High Resolution Modeling of the Water Balance in the Colorado Headwaters Region and Sensitivity to Climate Change

    NASA Astrophysics Data System (ADS)

    Rasmussen, R.; Ikeda, K.; Liu, C.; Gochis, D. J.; Chen, F.; Tewari, M.; Thompson, G.; Grubisic, V.; Yates, D. N.; Dudhia, J.; Barlage, M. J.; Gutmann, E. D.; Clark, M. P.

    2012-12-01

    Snowpack is the most important water source in the western U.S., and thus it is critical that water managers be provided with as accurate as possible estimate of the likely changes expected of this resource in the future. Previous climate studies have shown that the Headwaters region of the Colorado river seems to be a particularly difficult area for climate models to handle, with inconsistent snowpack trends in this region from both the 3rd and 4th IPCC reports (2001, 2007), despite consistent prediction of temperature increases in this region from all climate models. In order to provide more realistic estimates of the hydro-climatic changes in this region, a high resolution modeling study has been conducted using the climate version of the NCAR Weather Research and Forecast model. A variety of studies have been conducted, including an assessment of the model resolution required to simulate snowfall and snowpack in this region, the sensitivity to choice of model parameterization including the microphysics, evaluation of changes in precipitation efficiency using higher resolution simulations, and most recently changes to the water balance in a future climate. The paper will present the current and projected future changes of snowfall, snowpack, evapotranspiration and runoff over the Colorado Headwaters region using a continuous 8 years high resolution simulation at 4 km grid spacing. The future impacts will be evaluated by performing a climate sensitive run in which the 8 year current run is perturbed with the boundary conditions of the NCAR CCSM climate model for the mean conditions for 2050.

  18. The Arctic is especially sensitive to black carbon emissions from within the region

    NASA Astrophysics Data System (ADS)

    Sand, M.; Berntsen, T.; Seland; Kristjansson, J.

    2013-12-01

    The Arctic has warmed twice as fast as the global average over the past century and is likely to be especially sensitive to black carbon aerosols. Black carbon warm the air by absorbing solar radiation and can promote snow melt when deposited in snow. In this study we address the question of how sensitive the Arctic climate is to black carbon emitted within the Arctic compared to black carbon emitted at mid-latitudes. We consider the emission-climate response spectrum and present a set of experiments using a coupled global climate model. The climate model includes a snow model to simulate the climate effect of BC deposited on snow. A new emission data set including BC emissions from flaring and a seasonal variation in the domestic sector has been used. The dominating BC emissions in the Arctic is related to oil and gas fields in north western Russia. We find that most of the BC-induced warming in the Arctic is caused by black carbon deposited on snow, rather than in the atmosphere. Black carbon emitted in the Arctic is more likely to get deposited at the surface since most of the concentrations stay at lower altitudes. Especially during winter, BC emitted in North-Eurasia is transported into the high Arctic at low altitudes. We find that BC emitted within the Arctic has an almost 5-times larger Arctic surface temperature response (per unit of emitted mass) compared to emissions at mid-latitudes. Today there are few within-Arctic sources of BC, but the emissions are expected to grow due to increased human activity in the Arctic. There is a great need to improve cleaner technologies if further development is to take place in the Arctic, especially since the Arctic has a significantly higher sensitivity to BC emitted within the Arctic compared to BC emitted at mid-latitudes.

  19. Fungicide sensitivity testing of Cercospora beticola from sugarbeet in the Great Lakes Region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cercospora leaf spot (CLS), caused by Cercospora beticola (Sacc.), is the most serious foliar disease of sugarbeet (Beta vulgaris L.) worldwide. CLS is problematic in most sugarbeet growing regions and can cause significant economic losses due to decreases in both yield and sugar purity in the harve...

  20. Sensitivity of summer climate to anthropogenic land-cover change over the Greater Phoenix, AZ, region

    USGS Publications Warehouse

    Georgescu, M.; Miguez-Macho, G.; Steyaert, L.T.; Weaver, C.P.

    2008-01-01

    This work evaluates the first-order effect of land-use/land-cover change (LULCC) on the summer climate of one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, AZ, region. High-resolution-2-km grid spacing-Regional Atmospheric Modeling System (RAMS) simulations of three "wet" and three "dry" summers were carried out for two different land-cover reconstructions for the region: a circa 1992 representation based on satellite observations, and a hypothetical land-cover scenario where the anthropogenic landscape of irrigated agriculture and urban pixels was replaced with current semi-natural vegetation. Model output is evaluated with respect to observed air temperature, dew point, and precipitation. Our results suggest that development of extensive irrigated agriculture adjacent to the urban area has dampened any regional-mean warming due to urbanization. Consistent with previous observationally based work, LULCC produces a systematic increase in precipitation to the north and east of the city, though only under dry conditions. This is due to a change in background atmospheric stability resulting from the advection of both warmth from the urban core and moisture from the irrigated area. ?? 2008 Elsevier Ltd. All rights reserved.

  1. An optimisation model for regional integrated solid waste management II. Model application and sensitivity analyses.

    PubMed

    Najm, M Abou; El-Fadel, M; Ayoub, G; El-Taha, M; Al-Awar, F

    2002-02-01

    Increased environmental concerns and the emphasis on material and energy recovery are gradually changing the orientation of MSW management and planning. In this context, the application of optimisation techniques have been introduced to design the least cost solid waste management systems, considering the variety of management processes (recycling, composting, anaerobic digestion, incineration, and landfilling), and the existence of uncertainties associated with the number of system components and their interrelations. This study presents a model that was developed and applied to serve as a solid waste decision support system for MSW management taking into account both socio-economic and environmental considerations. The model accounts for solid waste generation rates, composition, collection, treatment, disposal as well as potential environmental impacts of various MSW management techniques. The model follows a linear programming formulation with the framework of dynamic optimisation. The model can serve as a tool to evaluate various MSW management alternatives and obtain the optimal combination of technologies for the handling, treatment and disposal of MSW in an economic and environmentally sustainable way. The sensitivity of various waste management policies is also addressed. The work is presented in a series of two papers: (I) model formulation, and (II) model application and sensitivity analysis. PMID:12020095

  2. Simulating smoke transport from wildland fires with a regional-scale air quality model: Sensitivity to uncertain wind fields

    NASA Astrophysics Data System (ADS)

    Garcia-Menendez, Fernando; Hu, Yongtao; Odman, Mehmet Talat

    2013-06-01

    Uncertainties associated with meteorological inputs which are propagated through atmospheric chemical transport models may constrain their ability to replicate the effects of wildland fires on air quality. Here, we investigate the sensitivity of predicted fine particulate matter (PM2.5) levels to uncertain wind fields by simulating the air quality impacts of two fires on an urban area with the Community Multiscale Air Quality modeling system (CMAQ). Brute-force sensitivity analyses show that modeled concentrations at receptors downwind from the fires are highly sensitive to variations in wind speed and direction. Additionally, uncertainty in wind fields produced with the Weather Research and Forecasting model was assessed by evaluating meteorological predictions against surface and upper air observations. Significant differences between predicted and observed wind fields were identified. Simulated PM2.5 concentrations at urban sites displayed large sensitivities to wind perturbations within the error range of meteorological inputs. The analyses demonstrate that normalized errors in CMAQ predictions attempting to model the regional impacts of fires on PM2.5 levels could be as high as 100% due to inaccuracies in wind data. Meteorological drivers may largely account for the considerable discrepancies between monitoring site observations and predicted concentrations. The results of this study demonstrate that limitations in fire-related air quality simulations cannot be overcome by solely improving emission rates.

  3. Sensitivity of lake ice regimes to climate change in the Nordic region

    NASA Astrophysics Data System (ADS)

    Gebre, S.; Boissy, T.; Alfredsen, K.

    2014-08-01

    A one-dimensional process-based multi-year lake ice model, MyLake, was used to simulate lake ice phenology and annual maximum lake ice thickness for the Nordic region comprising Fennoscandia and the Baltic countries. The model was first tested and validated using observational meteorological forcing on a candidate lake (Lake Atnsjøen) and using downscaled ERA-40 reanalysis data set. To simulate ice conditions for the contemporary period of 1961-2000, the model was driven by gridded meteorological forcings from ERA-40 global reanalysis data downscaled to a 25 km resolution using the Rossby Centre Regional Climate Model (RCA). The model was then forced with two future climate scenarios from the RCA driven by two different general circulation models (GCMs) based on the Special Report on Emissions Scenarios (SRES) A1B. The two climate scenarios correspond to two future time periods namely the 2050s (2041-2070) and the 2080s (2071-2100). To take into account the influence of lake morphometry, simulations were carried out for four different hypothetical lake depths (5 m, 10 m, 20 m, 40 m) placed at each of the 3708 grid cells. Based on a comparison of the mean predictions in the future 30-year periods with the control (1961-1990) period, ice cover durations in the region will be shortened by 1 to 11 weeks in 2041-2070, and 3 to 14 weeks in 2071-2100. Annual maximum lake ice thickness, on the other hand, will be reduced by a margin of up to 60 cm by 2041-2070 and up to 70 cm by 2071-2100. The simulated changes in lake ice characteristics revealed that the changes are less dependent on lake depths though there are slight differences. The results of this study provide a regional perspective of anticipated changes in lake ice regimes due to climate warming across the study area by the middle and end of this century.

  4. Sensitivity of lake ice regimes to climate change in the nordic region

    NASA Astrophysics Data System (ADS)

    Gebre, S.; Boissy, T.; Alfredsen, K.

    2013-03-01

    A one-dimensional process-based multi-year lake ice model, MyLake, was used to simulate lake ice phenology and annual maximum lake ice thickness for the Nordic region comprising Fennoscandia and the Baltic countries. The model was first tested and validated using observational meteorological forcing on a candidate lake (Lake Atnsjøen) and using downscaled ERA-40 reanalysis data set. To simulate ice conditions for the contemporary period of 1961-2000, the model was driven by gridded meteorological forcings from ERA-40 global reanalysis data downscaled to a 25 km resolution using the Rossby Center Regional Climate Model (RCA). The model was then forced with two future climate scenarios from the RCA driven by two different GCMs based on the SRES A1B emissions scenario. The two climate scenarios correspond to two future time periods namely the 2050s (2041-2070) and the 2080s (2071-2100). To take into account the influence of lake morphometry, simulations were carried out for four different hypothetical lake depths (5 m, 10 m, 20 m, 40 m) placed at each of the 3708 grid cells. Based on a comparison of the mean predictions in the future 30 yr periods with the control (1961-1990) period, ice cover durations in the region will be shortened by 1 to 11 weeks in 2041-2070, and 3 to 14 weeks in 2071-2100. Annual maximum lake ice thickness, on the other hand, will be reduced by a margin of up to 60 cm by 2041-2070 and up to 70 cm by 2071-2100. The simulated changes in lake ice characteristics revealed that the changes are less dependent on lake depths though there are slight differences. The results of this study provide a~regional perspective of anticipated changes in lake ice regimes due to climate warming across the study area by the middle and end of this century.

  5. Does ecosystem sensitivity to precipitation at the site-level conform to regional-scale predictions?.

    PubMed

    Wilcox, Kevin R; Blair, John M; Smith, Melinda D; Knapp, Alan K

    2016-03-01

    Central to understanding global C cycle dynamics is the functional relationship between precipitation and net primary production (NPP). At large spatial (regional) scales, the responsiveness of aboveground NPP (ANPP) to interannual variation in annual precipitation (AP; ANPPsens) is inversely related to site-level ANPP, coinciding with turnover of plant communities along precipitation gradients. Within ecosystems experiencing chronic alterations in water availability, plant community change will also occur with unknown consequences for ANPPsens. To examine the role plant community shifts may play in determining alterations in site-level ANPPPsens, we experimentally increased precipitation by approximately 35% for two decades in a native Central U.S. grassland. Consistent with regional models, ANPPsens decreased initially as water availability and ANPP increased. However, ANPPsens shifted back to ambient levels when mesic species increased in abundance in the plant community. Similarly, in grassland sites with distinct mesic and xeric plant communities and corresponding 50% differences in ANPP, ANPPsens did not differ over almost three decades. We conclude that responses in ANPPsens to chronic alterations in water availability within an ecosystem may not conform to regional AP-ANPP patterns, despite expected changes in ANPP and plant communities. The result is unanticipated functional resistance to climate change at the site scale. PMID:27197383

  6. Sensitivity of Sahel precipitation to albedo changes as depicted by a regional climate model

    NASA Astrophysics Data System (ADS)

    Boberg, Fredrik; Ali, Abdou; Christensen, Jens H.; Fensholt, Rasmus; May, Wilhelm; Rasmussen, Kjeld

    2014-05-01

    The idea of a long belt of new vegetation across the Sahel region in northern Africa to prevent desertification, generate precipitation, improve the soil quality, protect the biodiversity, etc., is tested using a number of regional climate model simulations. The vegetation belt, centered at 15 degrees N, is simulated through a decrease in model albedo, using the DMI HIRHAM5 model at a 50 km resolution. The simulations performed can be divided into 1) ERA Interim driven experiments for the period 1988-2012 and 2) EC-EARTH global climate model driven time slice experiments (reference period 1976-2005 and scenario period 2071-2100) using the emission scenarios RCP 4.5 and RCP 8.5. A number of experiments are performed, with different combinations of latitudinal extent of the green belt (between 1 and 2 degrees) and levels of numerical change in the albedo (between -0.06 and -0.03) with respect to a control run. The simulations show a significant change in the precipitation pattern and precipitation amount due to the altered albedo characteristics, especially south and southwest of the green wall, with areas experiencing an average increase in precipitation above 400 mm/year. The average precipitation for the region in the control run is 500 mm/year.

  7. Glutamate dysregulation in the trigeminal ganglion: a novel mechanism for peripheral sensitization of the craniofacial region.

    PubMed

    Laursen, J C; Cairns, B E; Dong, X D; Kumar, U; Somvanshi, R K; Arendt-Nielsen, L; Gazerani, P

    2014-01-01

    In the trigeminal ganglion (TG), satellite glial cells (SGCs) form a functional unit with neurons. It has been proposed that SGCs participate in regulating extracellular glutamate levels and that dysfunction of this SGC capacity can impact nociceptive transmission in craniofacial pain conditions. This study investigated whether SGCs release glutamate and whether elevation of TG glutamate concentration alters response properties of trigeminal afferent fibers. Immunohistochemistry was used to assess glutamate content and the expression of excitatory amino acid transporter (EAAT)1 and EAAT2 in TG sections. SGCs contained glutamate and expressed EAAT1 and EAAT2. Potassium chloride (10 mM) was used to evoke glutamate release from cultured rat SGCs treated with the EAAT1/2 inhibitor (3S)-3-[[3-[[4-(trifluoromethyl)ben zoyl]amino]phenyl]methoxy]-L-aspartic acid (TFB-TBOA) or control. Treatment with TFB-TBOA (1 and 10 μM) significantly reduced the glutamate concentration from 10.6 ± 1.1 to 5.8 ± 1.4 μM and 3.0 ± 0.8 μM, respectively (p<0.05). Electrophysiology experiments were conducted in anaesthetized rats to determine the effect of intraganglionic injections of glutamate on the response properties of ganglion neurons that innervated either the temporalis or masseter muscle. Intraganglionic injection of glutamate (500 mM, 3 μl) evoked afferent discharge and significantly reduced muscle afferent mechanical threshold. Glutamate-evoked discharge was attenuated bythe N-methyl-D-aspartate receptor antagonist 2-amino-5-phosphonovalerate (APV) and increased by TFB-TBOA, whereas mechanical sensitization was only sensitive to APV. Antidromic invasion of muscle afferent fibers by electrical stimulation of the caudal brainstem (10 Hz) or local anesthesia of the brainstem with lidocaine did not alter glutamate-induced mechanical sensitization. These findings provide a novel mechanism whereby dysfunctional trigeminal SGCs could contribute to cranial muscle tenderness in

  8. High sensitive X-ray films to detect electron showers in 100 GeV region

    NASA Technical Reports Server (NTRS)

    Taira, T.; Kazuno, M.; Shirai, T.; Tateyama, N.; Torii, S.; Nishimura, J.; Fujii, M.; Yoshida, A.; Aizu, H.; Nomura, Y.

    1985-01-01

    Nonscreen type X-ray films were used in emulsion chamber experiments to detect high energy showers in cosmic rays. Ranges of the detection threshold is from about 1 to 2 TeV depending on the exposure conditions. Different types of X-ray films and sheets i.e. high sensitive screen type X-ray films and luminescence sheets were tested. The threshold of the shower detection is found to be about 200 GeV, which is much lower than that of nonscreen type X-ray films. These films are useful to detect showers in the medium energy range, a few hundred GeV, of the cosmic ray electrons.

  9. Climate change signal over the Alpine region - sensitivity to GCM selection

    NASA Astrophysics Data System (ADS)

    Zubler, Elias M.; Fischer, Andreas M.; Liniger, Mark A.

    2015-04-01

    The use of multi-model ensembles has become a common and widely accepted practice to evaluate climate change signals and various aspects of the associated uncertainties. However, for regional analysis of climate change, it is not always feasible to use all of the available model simulations. Some models do not sufficiently represent processes that are important for a particular region, or they lack crucial topographic details to represent the corresponding climate in a realistic manner. When relying on regional climate model projections, a GCM selection is implicitly done, as not all of the available GCM simulations are being dynamically downscaled. Specifically, within EURO-CORDEX, more than 30 RCM simulations and more than 10 GCMs are provided for the strongest emission scenario RCP8.5 from the CMIP5 ensemble. Simulations with other emission scenarios are also provided. However, many RCMs in EURO-CORDEX are driven by one of only five of the available GCMs (CNRM-CM5, MPI-ESM, HadGEM, IPSL and EC-EARTH). It was shown previously that in particular RCM temperature responses tend to cluster according to their driving GCM. Therefore, it is important to better understand the relation among the GCMs. In multi-model ensembles as large as CMIP5, in which models tend to correlate due to their similar origin, model selection or weighting becomes an important issue. This study evaluates the distribution of climate change signals in the CMIP5 ensemble for temperature and precipitation over the Greater Alpine region and shows that different methods of model selection considerably influences the resulting temperature spread in the climate change signals at the end of the century relative to 1980-2009: excluding those GCMs with a poor representation of Alpine climate leads to a spread-difference of more than 1°C compared to a choice where all models are included and given the same weight. Furthermore, it is highlighted that the largest amount of spread can be retained with a

  10. Sensitivity of Downward Longwave Surface Radiation to Moisture and Cloud Changes in a High-elevation Region

    NASA Technical Reports Server (NTRS)

    Naud, Catherine M.; Chen, Yonghua; Rangwala, Imtiaz; Miller, James R.

    2013-01-01

    Several studies have suggested enhanced rates of warming in high-elevation regions since the latter half of the twentieth century. One of the potential reasons why enhanced rates of warming might occur at high elevations is the nonlinear relationship between downward longwave radiation (DLR) and specific humidity (q). Using ground-based observations at a high-elevation site in southwestern Colorado and coincident satellite-borne cloud retrievals, the sensitivity of DLR to changes in q and cloud properties is examined and quantified using a neural network method. It is also used to explore how the sensitivity of DLR to q (dDLR/dq) is affected by cloud properties. When binned by season, dDLR/dq is maximum in winter and minimum in summer for both clear and cloudy skies. However, the cloudy-sky sensitivities are smaller, primarily because (1) for both clear and cloudy skies dDLR/dq is proportional to 1/q, for q>0.5 g/kg, and (2) the seasonal values of q are on average larger in the cloudy-sky cases than in clear-sky cases. For a given value of q, dDLR/dq is slightly reduced in the presence of clouds and this reduction increases as q increases. In addition, DLR is found to be more sensitive to changes in cloud fraction when cloud fraction is large. In the limit of overcast skies, DLR sensitivity to optical thickness decreases as clouds become more opaque. These results are based on only one high-elevation site, so the conclusions here need to be tested at other high-elevation locations.