A variable conductance gas switch for intermediate temperature operation of liquid He/liquid N2 cryostats

NASA Technical Reports Server (NTRS)

Rayner, J. T.; Chuter, T. C.; Mclean, I. S.; Radostitz, J. V.; Nolt, I. G.

1988-01-01

A technique for establishing a stable intermediate temperature stage in liquid He/liquid N2 double vessel cryostats is described. The tertiary cold stage, which can be tuned to any temperature between 10 and 60 K, is ideal for cooling IR sensors for use in astronomy and physics applications. The device is called a variable-conductance gas switch. It is essentially a small chamber, located between the cold stage and liquid helium cold-face, whose thermal conductance may be controlled by varying the pressure of helium gas within the chamber. A key feature of this device is the large range of temperature control achieved with a very small (less than 10 mW) heat input from the cryogenic temperature control switch.

Holocene glacier and climate variations in Vestfirðir, Iceland, from the modeling of Drangajökull ice cap

NASA Astrophysics Data System (ADS)

Anderson, Leif S.; Flowers, Gwenn E.; Jarosch, Alexander H.; Aðalgeirsdóttir, Guðfinna Th; Geirsdóttir, Áslaug; Miller, Gifford H.; Harning, David J.; Thorsteinsson, Thorsteinn; Magnússon, Eyjólfur; Pálsson, Finnur

2018-06-01

Drangajökull is a maritime ice cap located in northwest (Vestfirðir) Iceland. Drangajökull's evolution is therefore closely linked to atmospheric and ocean variability. In order to better constrain the Holocene climate and glacier history of Vestfirðir we model the past evolution of Drangajökull ice cap. Simulations from 10 ka to present are forced by general circulation model output, ice-core-based temperature reconstructions, and sea-surface temperature reconstructions. Based on these 10-thousand year simulations, Drangajökull did not persist through the Holocene. We estimate that air temperatures were 2.5-3.0 °C higher during the Holocene Thermal Maximum than the local 1960-1990 average. Simulations support Drangajökull's late Holocene inception between 2 and 1 ka, though intermittent ice likely occupied cirques as early as 2.6 ka. Drangajökull is primarily a Little Ice Age ice cap: it expanded between 1300 and 1750 CE, with the most rapid growth occurring between 1600 and 1750 CE. The maximum Holocene extent of Drangajökull occurred between 1700 and 1925 CE, despite the lowest late Holocene temperatures, occurring between 1650 and 1720 CE. Between 1700 and 1925 CE temperatures were likely 0.6-0.8 °C lower than the 1950-2015 reference temperature. The modern equilibrium line altitude (ELA) is bracketed by topographic thresholds: a 1 °C temperature increase from the modern ELA would eliminate the ice cap's accumulation area, while a reduction of 0.5 °C would lead to the rapid expansion of the ice cap across Vestfirðir. The proximity of Drangajökull to topographic thresholds may explain its late inception and rapid expansion during the Little Ice Age.

CRISM Hyperspectral Data Filtering with Application to MSL Landing Site Selection

NASA Astrophysics Data System (ADS)

Seelos, F. P.; Parente, M.; Clark, T.; Morgan, F.; Barnouin-Jha, O. S.; McGovern, A.; Murchie, S. L.; Taylor, H.

2009-12-01

We report on the development and implementation of a custom filtering procedure for Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) IR hyperspectral data that is suitable for incorporation into the CRISM Reduced Data Record (RDR) calibration pipeline. Over the course of the Mars Reconnaissance Orbiter (MRO) Primary Science Phase (PSP) and the ongoing Extended Science Phase (ESP) CRISM has operated with an IR detector temperature between ~107 K and ~127 K. This ~20 K range in operational temperature has resulted in variable data quality, with observations acquired at higher detector temperatures exhibiting a marked increase in both systematic and stochastic noise. The CRISM filtering procedure consists of two main data processing capabilities. The primary systematic noise component in CRISM IR data appears as along track or column oriented striping. This is addressed by the robust derivation and application of an inter-column ratio correction frame. The correction frame is developed through the serial evaluation of band specific column ratio statistics and so does not compromise the spectral fidelity of the image cube. The dominant CRISM IR stochastic noise components appear as isolated data spikes or column oriented segments of variable length with erroneous data values. The non-systematic noise is identified and corrected through the application of an iterative-recursive kernel modeling procedure which employs a formal statistical outlier test as the iteration control and recursion termination criterion. This allows the filtering procedure to make a statistically supported determination between high frequency (spatial/spectral) signal and high frequency noise based on the information content of a given multidimensional data kernel. The governing statistical test also allows the kernel filtering procedure to be self regulating and adaptive to the intrinsic noise level in the data. The CRISM IR filtering procedure is scheduled to be incorporated into the next augmentation of the CRISM IR calibration (version 3). The filtering algorithm will be applied to the I/F data (IF) delivered to the Planetary Data System (PDS), but the radiance on sensor data (RA) will remain unfiltered. The development of CRISM hyperspectral analysis products in support of the Mars Science Laboratory (MSL) landing site selection process has motivated the advance of CRISM-specific data processing techniques. The quantitative results of the CRISM IR filtering procedure as applied to CRISM observations acquired in support of MSL landing site selection will be presented.

Variability in surface infrared reflectance of thirteen nitrile rubber gloves at key wavelengths for analysis of captan.

PubMed

Phalen, R N; Que Hee, Shane S

2007-02-01

The aim of this study was to investigate the surface variability of 13 powder-free, unlined, and unsupported nitrile rubber gloves using attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectrophotometry at key wavelengths for analysis of captan contamination. The within-glove, within-lot, and between-lot variability was measured at 740, 1124, 1252, and 1735 cm(-1), the characteristic captan reflectance minima wavelengths. Three glove brands were assessed after conditioning overnight at relative humidity (RH) values ranging from 2 +/- 1 to 87 +/- 4% and temperatures ranging from -8.6 +/- 0.7 to 59.2 +/- 0.9 degrees C. For all gloves, 1735 cm(-1) provided the lowest background absorbance and greatest potential sensitivity for captan analysis on the outer glove surface: absorbances ranged from 0.0074 +/- 0.0005 (Microflex) to 0.0195 +/- 0.0024 (SafeSkin); average within-glove coefficients of variation (CV) ranged from 2.7% (Best, range 0.9-5.3%) to 10% (SafeSkin, 1.2-17%); within-glove CVs greater than 10% were for one brand (SafeSkin); within-lot CVs ranged from 2.8% (Best N-Dex) to 28% (SafeSkin Blue); and between-lot variation was statistically significant (p < or = 0.05) for all but two SafeSkin lots. The RH had variable effects dependent on wavelength, being minimal at 1735, 1252, and 1124 cm(-1) and highest at 3430 cm(-1) (O-H stretch region). There was no significant effect of temperature conditioning. Substantial within-glove, within-lot, and between-lot variability was observed. Thus, surface analysis using ATR-FT-IR must treat glove brands and lots as different. ATR-FT-IR proved to be a useful real-time analytical tool for measuring glove variability, detecting surface humidity effects, and choosing selective and sensitive wavelengths for analysis of nonvolatile surface contaminants.

Ground-based thermography of fluvial systems at low and high discharge reveals potential complex thermal heterogeneity driven by flow variation and bioroughness

USGS Publications Warehouse

Cardenas, M.B.; Harvey, J.W.; Packman, A.I.; Scott, D.T.

2008-01-01

Temperature is a primary physical and biogeochemical variable in aquatic systems. Field-based measurement of temperature at discrete sampling points has revealed temperature variability in fluvial systems, but traditional techniques do not readily allow for synoptic sampling schemes that can address temperature-related questions with broad, yet detailed, coverage. We present results of thermal infrared imaging at different stream discharge (base flow and peak flood) conditions using a handheld IR camera. Remotely sensed temperatures compare well with those measured with a digital thermometer. The thermal images show that periphyton, wood, and sandbars induce significant thermal heterogeneity during low stages. Moreover, the images indicate temperature variability within the periphyton community and within the partially submerged bars. The thermal heterogeneity was diminished during flood inundation, when the areas of more slowly moving water to the side of the stream differed in their temperature. The results have consequences for thermally sensitive hydroelogical processes and implications for models of those processes, especially those that assume an effective stream temperature. Copyright ?? 2008 John Wiley & Sons, Ltd.

Sorption-desorption of fipronil in some soils, as influenced by ionic strength, pH and temperature.

PubMed

Singh, Anand; Srivastava, Anjana; Srivastava, Prakash C

2016-08-01

The sorption-desorpion of fipronil insecticide is influenced by soil properties and variables such as pH, ionic strength, temperature, etc. A better understanding of soil properties and these variables in sorption-desorption processes by quantification of fipronil using liquid chromatography may help to optimise suitable soil management to reduce contamination of surface and groundwaters. In the present investigation, the sorption-desorption of fipronil was studied in some soils at varying concentrations, ionic strengths, temperatures and pH values, and IR specta of fipronil sorbed onto soils were studied. The sorption of fipronil onto soils conformed to the Freundlich isotherm model. The sorption-desorption of fipronil varied with ionic strength in each of the soils. Sorption decreased but desorption increased with temperature. Sorption did not change with increasing pH, but for desorption there was no correlation. The cumulative desorption of fipronil from soil was significantly and inversely related to soil organic carbon content. IR spectra of sorbed fipronil showed the involvement of amino, nitrile, sulfone, chloro and fluoro groups and the pyrazole nucleus of the fipronil molecule. The sorption of fipronil onto soils appeared to be a physical process with the involvement of hydrogen bonding. An increase in soil organic carbon may help to reduce desorption of fipronil. High-temperature regimes are more conducive to the desorption. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Silicon Based Schottky Barrier Infrared Sensors For Power System And Industrial Applications

NASA Astrophysics Data System (ADS)

Elabd, Hammam; Kosonocky, Walter F.

1984-03-01

Schottky barrier infrared charge coupled device sensors (IR-CCDs) have been developed. PtSi Schottky barrier detectors require cooling to liquid Nitrogen temperature and cover the wavelength range between 1 and 6 μm. The PtSi IR-CCDs can be used in industrial thermography with NEAT below 0.1°C. Pd Si-Schottkybarrier detectors require cooling to 145K and cover the spectral range between 1 and 3.5 μm. 11d2Si-IR-CCDs can be used in imaging high temperature scenes with NE▵T around 100°C. Several high density staring area and line imagers are available. Both interlaced and noninterlaced area imagers can be operated with variable and TV compatible frame rates as well as various field of view angles. The advantages of silicon fabrication technology in terms of cost and high density structures opens the doors for the design of special purpose thermal camera systems for a number of power aystem and industrial applications.

Variability and trends in area, location, cloudiness and cloud top temperature of the ITCZ in the east to central Pacific over the past 30 years

NASA Astrophysics Data System (ADS)

Magnusdottir, G.; Bain, C.; Smyth, P.; Stern, H.; Knapp, K.

2010-12-01

A team of multidisciplinary scientists at the University of California Irvine has developed a novel spatial-temporal statistical model to detect the presence/absence of the ITCZ in high-resolution instantaneous satellite data. The Markov random field (MRF) statistical model is briefly introduced and compared to other automatic methods such as thresholding. The statistical model emulates human identification of the ITCZ as an envelope of convective activity (as seen in different fields) plus produces the same results given the same data, which may not be the case for human analysis. The MRF statistical model uses satellite data at a given location as well as information from its neighboring points (in time and space) to decide whether the given point is classified as ITCZ or non-ITCZ. Two different labels of ITCZ occurrence are produced. IR-only labels result from running the model with 3-hourly infrared data available for a 30 yr period, 1980--2009. Data-all labels result from running the model with additional satellite data (visible and total precipitable water), available from 1995--2008. IR-only labels detect less area of ITCZ than Data-all labels, especially where the ITCZ is shallower. Yet, qualitatively, the results for the two sets of labels are similar. Here, we focus on results from the IR-only labels over the east Pacific for the past 30 summer half-years (May to October). The IR data are from the HURSAT Basin data of NOAA’s National Climatic Data Center, which are derived from ISCCP B1 data. The data were collected from radiometers on different geostationary satellites. The IR channel data were recalibrated to reduce inter-satellite differences. The seasonal distribution of the ITCZ through the summer half year is presented, showing typical location and extent. The ITCZ is mostly confined to the eastern Pacific in May, and becomes more zonally distributed towards September and October each year. Northward and westward shifts in the location of the ITCZ occur in line with the seasonal cycle and warm sea surface temperatures. The ITCZ is quite variable on interannual time scales and highly correlated with ENSO variability. When we removed the ENSO signal from labels, interannual variability remained high. The resulting IR-only labels, showed no evidence of a trend in location, nor evidence of a trend in area for the 30 yr period. However, a trend in cloudiness within labels is observed and will be discussed.

Climate influences on the cost-effectiveness of vector-based interventions against malaria in elimination scenarios

PubMed Central

Parham, Paul E.; Hughes, Dyfrig A.

2015-01-01

Despite the dependence of mosquito population dynamics on environmental conditions, the associated impact of climate and climate change on present and future malaria remains an area of ongoing debate and uncertainty. Here, we develop a novel integration of mosquito, transmission and economic modelling to assess whether the cost-effectiveness of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) against Plasmodium falciparum transmission by Anopheles gambiae s.s. mosquitoes depends on climatic conditions in low endemicity scenarios. We find that although temperature and rainfall affect the cost-effectiveness of IRS and/or LLIN scale-up, whether this is sufficient to influence policy depends on local endemicity, existing interventions, host immune response to infection and the emergence rate of insecticide resistance. For the scenarios considered, IRS is found to be more cost-effective than LLINs for the same level of scale-up, and both are more cost-effective at lower mean precipitation and higher variability in precipitation and temperature. We also find that the dependence of peak transmission on mean temperature translates into optimal temperatures for vector-based intervention cost-effectiveness. Further cost-effectiveness analysis that accounts for country-specific epidemiological and environmental heterogeneities is required to assess optimal intervention scale-up for elimination and better understand future transmission trends under climate change. PMID:25688017

Long term evolution of temperature in the venus upper atmosphere at the evening and morning terminators

NASA Astrophysics Data System (ADS)

Krause, P.; Sornig, M.; Wischnewski, C.; Kostiuk, T.; Livengood, T. A.; Herrmann, M.; Sonnabend, G.; Stangier, T.; Wiegand, M.; Pätzold, M.; Mahieux, A.; Vandaele, A. C.; Piccialli, A.; Montmessin, F.

2018-01-01

This paper contains a comprehensive dataset of long-term observations between 2009 and 2015 at the upper mesosphere/lower thermosphere providing temperature values at different locations of the morning and evening side of the terminator of Venus. Temperature information is obtained by line-resolved spectroscopy of Doppler broadened CO2 transitions features. Results are restricted to a pressure level of 1 μbar, ∼110 km altitude due the nature of the addressed non-LTE CO2 emission line at 10 μm. The required high spectral resolution of the instrumentation is provided by the ground-based spectrometers THIS (University of Cologne) and HIPWAC (NASA GSFC). For the first time upper mesosphere/lower thermosphere temperatures at the Venusian terminator derived from IR-het spectroscopy between 2009 and 2015 are investigated in order to clarify the local-time dependences, latitudinal dependences and the long-term trend. Measured temperatures were distributed in the range between 140 K and 240 K, with mean values equal to 199 K ± 17 K for the morning side of the terminator and 195 K ± 19 K for the evening side of the terminator. Within the uncertainty no difference between the averaged morning and evening terminator side temperature is found. In addition, no strong latitudinal dependency is observed at these near terminator local times. In contrast IR-het data from 2009 show a strong latitudinal dependency at noon, with a temperature difference of around 60 K between the equatorial and polar region (Sonnabend et al., 2012). Accord with the instruments of the Venus Express mission a northern-southern hemispherical symmetry is observed (Mahieux et al., 2012; Piccialli et al., 2015). The data shows no consistent long-term temperature trend throughout the six years of observation, but a variability in the order of tens of Kelvin for the different observing runs representing a time step of few month to two years. This is about the same order of magnitude as the variability within a single run with a typically time range of 2-10 days. This variation is not connected to the solar cycle. Sub-millimeter observations by Clancy et al. found a relation between temperatures and long-term variation in mesospheric water vapor, SO2, and sulfate aerosols (Clancy and Muhleman, 1991; Clancy et al., 2012). SO2 column densities observed by SOIR at the terminator are fairly stable over the time period of 2006-2011 (Mahieux et al., 2015), supporting the hypothesis of a relation between SO2 and temperature variations. The temperatures derived from the infrared heterodyne spectroscopy (IR-het) are compared to results from the Venus Express space mission (VEx). A consistence with the temperatures from the VEx instruments SOIR, VIRTIS and SPICAV is found. As the instruments probe different local time, SPICAV probes the pure nightside, SOIR across the terminator and IR-het the pure dayside atmosphere it is not surprising that the IR-het temperatures are mostly on the warmer side compared to results from SPICAV and SOIR.

Spatial variability of surface temperature as related to cropping practice with implications for irrigation management

NASA Technical Reports Server (NTRS)

Hatfield, J. L.; Millard, J. P.; Reginato, R. J.; Jackson, R. D.; Idso, S. B.; Pinter, P. J., Jr.; Goettelman, R. C.

1980-01-01

Crop stress measured using thermal infrared emission is evaluated with the stress-degree-day (SDD) concept. Throughout the season, the accumulation of SDD during the reproductive stage of growth is inversely related to yield. This relationship is shown for durum wheat, hard red winter wheat, barley, grain sorghum and soybeans. It is noted that SDD can be used to schedule irrigations for maximizing yields and for applying remotely sensed data to management of water resources. An airborne flight with a thermal-IR scanner was used to examine the variability in temperature that may exist from one field to another and to determine realistic within-field temperature variations. It was found that the airborne and the ground-based data agreed very well and that there was less variability in the fields that were completely covered with crops than those of bare soil.

Unusual thermal expansion of Sr{sub 2}IrO{sub 4}: A variable temperature synchrotron X-ray diffraction study

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

Ranjbar, Ben; Kennedy, Brendan J.

The structure of Sr{sub 2}IrO{sub 4} has been studied between 20 and 1273 K using synchrotron X-ray diffraction. Sr{sub 2}IrO{sub 4} undergoes an apparently continuous transition from I4{sub 1}/acd to I4/mmm near 1123 K. The cooperative tilting of the corner sharing IrO{sub 6} octahedra in I4{sub 1}/acd results in highly anisotropic and unusual thermal expansion behavior with negative thermal expansion along the c-axis. - Graphical abstract: The progressive reduction in the magnitude of the tilting of the corner sharing IrO{sub 6} octahedra in Sr{sub 2}IrO{sub 4} results in negative thermal expansion along the c-axis before undergoing an apparently continuous transitionmore » from I4{sub 1}/acd to I4/mmm near 1123 K. - Highlights: • Thermal expansion of Sr{sub 2}IrO{sub 4} was studied using Synchrotron-XRD. • Unusual negative thermal expansion along c-axis observed. • I4{sub 1}/acd→I4/mmm phase transition detected near 1120 K. • Tilting of the corner sharing IrO{sub 6} octahedra related to the observed NTE.« less

A method based on infrared detection for determining the moisture content of ceramic plaster materials.

PubMed

Macias-Melo, E V; Aguilar-Castro, K M; Alvarez-Lemus, M A; Flores-Prieto, J J

2015-09-01

In this work, we describe a methodology for developing a mathematical model based on infrared (IR) detection to determine the moisture content (M) in solid samples. For this purpose, an experimental setup was designed, developed and calibrated against the gravimetric method. The experimental arrangement allowed for the simultaneous measurement of M and the electromotive force (EMF), fitting the experimental variables as much as possible. These variables were correlated by a mathematical model, and the obtained correlation was M=1.12×exp(3.47×EMF), ±2.54%. This finding suggests that it is feasible to measure the moisture content when it has greater values than 2.54%. The proposed methodology could be used for different conditions of temperature, relative humidity and drying rates to evaluate the influence of these variables on the amount of energy received by the IR detector. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Mechanistic modelling of infrared mediated energy transfer during the primary drying step of a continuous freeze-drying process.

PubMed

Van Bockstal, Pieter-Jan; Mortier, Séverine Thérèse F C; De Meyer, Laurens; Corver, Jos; Vervaet, Chris; Nopens, Ingmar; De Beer, Thomas

2017-05-01

Conventional pharmaceutical freeze-drying is an inefficient and expensive batch-wise process, associated with several disadvantages leading to an uncontrolled end product variability. The proposed continuous alternative, based on spinning the vials during freezing and on optimal energy supply during drying, strongly increases process efficiency and improves product quality (uniformity). The heat transfer during continuous drying of the spin frozen vials is provided via non-contact infrared (IR) radiation. The energy transfer to the spin frozen vials should be optimised to maximise the drying efficiency while avoiding cake collapse. Therefore, a mechanistic model was developed which allows computing the optimal, dynamic IR heater temperature in function of the primary drying progress and which, hence, also allows predicting the primary drying endpoint based on the applied dynamic IR heater temperature. The model was validated by drying spin frozen vials containing the model formulation (3.9mL in 10R vials) according to the computed IR heater temperature profile. In total, 6 validation experiments were conducted. The primary drying endpoint was experimentally determined via in-line near-infrared (NIR) spectroscopy and compared with the endpoint predicted by the model (50min). The mean ratio of the experimental drying time to the predicted value was 0.91, indicating a good agreement between the model predictions and the experimental data. The end product had an elegant product appearance (visual inspection) and an acceptable residual moisture content (Karl Fischer). Copyright © 2017 Elsevier B.V. All rights reserved.

Climate influences on the cost-effectiveness of vector-based interventions against malaria in elimination scenarios.

PubMed

Parham, Paul E; Hughes, Dyfrig A

2015-04-05

Despite the dependence of mosquito population dynamics on environmental conditions, the associated impact of climate and climate change on present and future malaria remains an area of ongoing debate and uncertainty. Here, we develop a novel integration of mosquito, transmission and economic modelling to assess whether the cost-effectiveness of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) against Plasmodium falciparum transmission by Anopheles gambiae s.s. mosquitoes depends on climatic conditions in low endemicity scenarios. We find that although temperature and rainfall affect the cost-effectiveness of IRS and/or LLIN scale-up, whether this is sufficient to influence policy depends on local endemicity, existing interventions, host immune response to infection and the emergence rate of insecticide resistance. For the scenarios considered, IRS is found to be more cost-effective than LLINs for the same level of scale-up, and both are more cost-effective at lower mean precipitation and higher variability in precipitation and temperature. We also find that the dependence of peak transmission on mean temperature translates into optimal temperatures for vector-based intervention cost-effectiveness. Further cost-effectiveness analysis that accounts for country-specific epidemiological and environmental heterogeneities is required to assess optimal intervention scale-up for elimination and better understand future transmission trends under climate change. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

2D surface temperature measurement of plasma facing components with modulated active pyrometry

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

Amiel, S.; Loarer, T.; Pocheau, C.

2014-10-01

In nuclear fusion devices, such as Tore Supra, the plasma facing components (PFC) are in carbon. Such components are exposed to very high heat flux and the surface temperature measurement is mandatory for the safety of the device and also for efficient plasma scenario development. Besides this measurement is essential to evaluate these heat fluxes for a better knowledge of the physics of plasma-wall interaction, it is also required to monitor the fatigue of PFCs. Infrared system (IR) is used to manage to measure surface temperature in real time. For carbon PFCs, the emissivity is high and known (ε ~more » 0.8), therefore the contribution of the reflected flux from environment and collected by the IR cameras can be neglected. However, the future tokamaks such as WEST and ITER will be equipped with PFCs in metal (W and Be/W, respectively) with low and variable emissivities (ε ~ 0.1–0.4). Consequently, the reflected flux will contribute significantly in the collected flux by IR camera. The modulated active pyrometry, using a bicolor camera, proposed in this paper allows a 2D surface temperature measurement independently of the reflected fluxes and the emissivity. Experimental results with Tungsten sample are reported and compared with simultaneous measurement performed with classical pyrometry (monochromatic and bichromatic) with and without reflective flux demonstrating the efficiency of this method for surface temperature measurement independently of the reflected flux and the emissivity.« less

PHOTOMETRIC MONITORING OF THE COLDEST KNOWN BROWN DWARF WITH THE SPITZER SPACE TELESCOPE

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

Esplin, T. L.; Luhman, K. L.; Cushing, M. C.

2016-11-20

Because WISE J085510.83-071442.5 (hereafter WISE 0855-0714) is the coldest known brown dwarf (∼250 K) and one of the Sun’s closest neighbors (2.2 pc), it offers a unique opportunity to study a planet-like atmosphere in an unexplored regime of temperature. To detect and characterize inhomogeneities in its atmosphere (e.g., patchy clouds, hot spots), we have performed time-series photometric monitoring of WISE 0855-0714 at 3.6 and 4.5 μ m with the Spitzer Space Telescope during two 23 hr periods that were separated by several months. For both bands, we have detected variability with peak-to-peak amplitudes of 4%–5% and 3%–4% in the firstmore » and second epochs, respectively. The light curves are semiperiodic in the first epoch for both bands, but they are more irregular in the second epoch. Models of patchy clouds have predicted a large increase in mid-infrared (mid-IR) variability amplitudes (for a given cloud covering fraction) with the appearance of water ice clouds at T {sub eff} < 375 K, so if such clouds are responsible for the variability of WISE 0855-0714, then its small amplitudes of variability indicate a very small deviation in cloud coverage between hemispheres. Alternatively, the similarity in mid-IR variability amplitudes between WISE 0855-0714 and somewhat warmer T and Y dwarfs may suggest that they share a common origin for their variability (i.e., not water clouds). In addition to our variability data, we have examined other constraints on the presence of water ice clouds in the atmosphere of WISE 0855-0714, including the recent mid-IR spectrum from Skemer et al. (2016). We find that robust evidence of such clouds is not yet available.« less

The Brightening of the Red Supergiant alpha Ori

NASA Astrophysics Data System (ADS)

Wasatonic, R. P.; Guinan, E. F.

2016-09-01

We have been carrying out V-band and Wing TiO-band and Near-IR photoelectric photometry of the semi-regular variable red supergiant alpha Ori (Betelgeuse) over last 20 yrs. Photometry obtained during early to mid September 2016 indicates that the star is at (or near) maximum light at = +0.29 mag. Measures of TiO-band and near-IR colors indicate that alpha Ori has undergone a temperature increase of about +120 K and has an estimated spectral type of M0.5 Iab. Because alpha Ori is one of the nearest Type II SN progenitors, it an important star to monitor.

Structure, magnetism and electronic properties in 3d-5d based double perovskite ({Sr_{1-x}} Y x )2FeIrO6

NASA Astrophysics Data System (ADS)

Kharkwal, K. C.; Pramanik, A. K.

2017-12-01

The 3d-5d based double perovskites are of current interest as they provide model systems to study the interplay between electronic correlation (U) and spin-orbit coupling (SOC). Here, we report detailed structural, magnetic and transport properties of doped double perovskite material (Sr1-x Y x )2FeIrO6 with x ≤slant 0.2 . With substitution of Y, the system retains its original crystal structure but structural parameters change with x in nonmonotonic fashion. The magnetization data for Sr2FeIrO6 show antiferromagnetic type magnetic transition around 45 K however, a close inspection of the data indicates a weak magnetic phase transition around 120 K. No change of structural symmetry has been observed down to low temperature, although the lattice parameters show sudden changes around the magnetic transitions. Sr2FeIrO6 shows an insulating behavior over the whole temperature range, which nevertheless does not change with Y substitution. The nature of charge conduction is found to follow thermally activated Mott’s variable range hopping and power law behavior for parent and doped samples, respectively. Interestingly, evolution of structural, magnetic and transport behavior in (Sr1-x Y x )2FeIrO6 is observed to reverse with x > 0.1 , which is believed to arise due to a change in the transition metal ionic state.

Structure, magnetism and electronic properties in 3d-5d based double perovskite ([Formula: see text]Y x )2FeIrO6.

PubMed

Kharkwal, K C; Pramanik, A K

2017-11-13

The 3d-5d based double perovskites are of current interest as they provide model systems to study the interplay between electronic correlation (U) and spin-orbit coupling (SOC). Here, we report detailed structural, magnetic and transport properties of doped double perovskite material ([Formula: see text]Y x ) 2 FeIrO 6 with [Formula: see text]. With substitution of Y, the system retains its original crystal structure but structural parameters change with x in nonmonotonic fashion. The magnetization data for Sr 2 FeIrO 6 show antiferromagnetic type magnetic transition around 45 K; however, a close inspection of the data indicates a weak magnetic phase transition around 120 K. No change of structural symmetry has been observed down to low temperature, although the lattice parameters show sudden changes around the magnetic transitions. Sr 2 FeIrO 6 shows an insulating behavior over the whole temperature range, which nevertheless does not change with Y substitution. The nature of charge conduction is found to follow thermally activated Mott's variable range hopping and power law behavior for parent and doped samples, respectively. Interestingly, evolution of structural, magnetic and transport behavior in ([Formula: see text]Y x ) 2 FeIrO 6 is observed to reverse with [Formula: see text], which is believed to arise due to a change in the transition metal ionic state.

Recent Climate Variability in Antarctica from Satellite-derived Temperature Data

NASA Technical Reports Server (NTRS)

Schneider, David P.; Steig, Eric J.; Comiso, Josefino C.

2004-01-01

Recent Antarctic climate variability on month-to-month to interannual time scales is assessed through joint analysis of surface temperatures from satellite thermal infrared observations (T(sub IR)) and passive microwave brightness temperatures (T(sub B)). Although Tw data are limited to clear-sky conditions and T(sub B) data are a product of the temperature and emissivity of the upper approx. 1m of snow, the two data sets share significant covariance. This covariance is largely explained by three empirical modes, which illustrate the spatial and temporal variability of Antarctic surface temperatures. T(sub B) variations are damped compared to TIR variations, as determined by the period of the temperature forcing and the microwave emission depth; however, microwave emissivity does not vary significantly in time. Comparison of the temperature modes with Southern Hemisphere (SH) 500-hPa geopotential height anomalies demonstrates that Antarctic temperature anomalies are predominantly controlled by the principal patterns of SH atmospheric circulation. The leading surface temperature mode strongly correlates with the Southern Annular Mode (SAM) in geopotential height. The second temperature mode reflects the combined influences of the zonal wavenumber-3 and Pacific South American (PSA) patterns in 500-hPa height on month-to-month timescales. ENSO variability projects onto this mode on interannual timescales, but is not by itself a good predictor of Antarctic temperature anomalies. The third temperature mode explains winter warming trends, which may be caused by blocking events, over a large region of the East Antarctic plateau. These results help to place recent climate changes in the context of Antarctica's background climate variability and will aid in the interpretation of ice core paleoclimate records.

Electron transfer rate on mixed valence states of Class II/III transition for N, N'-diphenyl-1,4-phenylenediamine structures as a polyaniline unit

NASA Astrophysics Data System (ADS)

Nishiumi, Toyohiko; Nomura, Yasuhiro; Higuchi, Masayoshi; Yamamoto, Kimihisa

2003-08-01

The first example of the determination of the electron transfer rate ( λ, V, Δ G*, kth) for N, N'-diphenyl-1,4-phenylenediamine derivatives using the Marcus-Hush theory is described. These results were in good agreement with the ones obtained using variable-temperature IR spectra measurements.

Electrically-Active Convection in Tropical Easterly Waves and Implications for Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.; Cecil, Daniel J.

2012-01-01

In this study, we investigate the characteristics of tropical easterly wave convection and the possible implications of convective structure on tropical cyclogenesis and intensification over the Atlantic Ocean and East Pacific using data from the Tropical Rainfall Measurement Mission Microwave Imager, Precipitation Radar (PR), and Lightning Imaging Sensor as well as infrared (IR) brightness temperature data from the NASA global-merged IR brightness temperature dataset. Easterly waves were partitioned into northerly, southerly, trough, and ridge phases based on the 700-hPa meridional wind from the NCEP-NCAR reanalysis dataset. Waves were subsequently divided according to whether they did or did not develop tropical cyclones (i.e., developing and nondeveloping, respectively), and developing waves were further subdivided according to development location. Finally, composites as a function of wave phase and category were created using the various datasets. Results suggest that the convective characteristics that best distinguish developing from nondeveloping waves vary according to where developing waves spawn tropical cyclones. For waves that developed a cyclone in the Atlantic basin, coverage by IR brightness temperatures .240 K and .210 K provide the best distinction between developing and nondeveloping waves. In contrast, several variables provide a significant distinction between nondeveloping waves and waves that develop cyclones over the East Pacific as these waves near their genesis location including IR threshold coverage, lightning flash rates, and low-level (<4.5 km) PR reflectivity. Results of this study may be used to help develop thresholds to better distinguish developing from nondeveloping waves and serve as another aid for tropical cyclogenesis forecasting.

Characterization of Iridium Coated Rhenium Used in High-Temperature, Radiation-Cooled Rocket Thrusters

NASA Technical Reports Server (NTRS)

Stulen, R. H.; Boehme, D. R.; Clift, W. M.; McCarty, K. F.

1990-01-01

Materials used for radiation-cooled rocket thrusters must be capable of surviving under extreme conditions of high-temperatures and oxidizing environments. While combustion efficiency is optimized at high temperatures, many refractory metals are unsuitable for thruster applications due to rapid material loss from the formation of volatile oxides. This process occurs during thruster operation by reaction of the combustion products with the material surface. Aerojet Technical Systems has developed a thruster cone chamber constructed of Re coated with Ir on the inside surface where exposure to the rocket exhaust occurs. Re maintains its structural integrity at high temperature and the Ir coating is applied as an oxidation barrier. Ir also forms volatile oxide species (IrO2 and IrO3) but at a considerably slower rate than Re. In order to understand the performance limits of Ir-coated Re thrusters, we are investigating the interdiffusion and oxidation kinetics of Ir/Re. The formation of iridium and rhenium oxides has been monitored in situ by Raman spectroscopy during high temperature exposure to oxygen. For pure Ir, the growth of oxide films as thin as approximately 200 A could be easily detected and the formation of IrO2 was observed at temperatures as low as 600 C. Ir/Re diffusion test specimens were prepared by magnetron sputtering of Ir on Re substrates. Concentration profiles were determined by sputter Auger depth profiles of the heat treated specimens. Significant interdiffusion was observed at temperatures as low as 1000 C. Measurements of the activation energy suggest that below 1350 C, the dominant diffusion path is along defects, most likely grain boundaries, rather than bulk diffusion through the grains. The phases that form during interdiffusion have been examined by x ray diffraction. Analysis of heated test specimens indicates that the Ir-Re reaction produces a solid solution phase of Ir dissolved in the HCP structure of Re.

Leveraging Oceanic and Surface Intensive Field Campaign Data Sets for Validation and Improvement of Recent Hyperspectral IR Satellite Data Products

NASA Astrophysics Data System (ADS)

Joseph, E.; Nalli, N. R.; Oyola, M. I.; Morris, V. R.; Sakai, R.

2014-12-01

An overview is given of research to validate or improve the retrieval of environmental data records (EDRs) from recently deployed hyperspectral IR satellite sensors such as Suomi NPP Cross-track Infrared Microwave Sounder Suite (CrIMSS). The effort centers around several surface field intensive campaigns that are designed or leveraged for EDR validation. These data include ship-based observations of upper air ozone, pressure, temperature and relative humidity soundings; aerosol and cloud properties; and sea surface temperature. Similar intensive data from two land-based sites are also utilized as well. One site, the Howard University Beltsville site, is at a single point location but has a comprehensive array of observations for an extended period of time. The other land site, presently being deployed by the University at Albany, is under development with limited upper air soundings but will have regionally distributed surface based microwave profiling of temperature and relative humidity on the scale of 10 - 50 km and other standard meteorological observations. Combined these observations provide data that are unique in their wide range including, a variety of meteorological conditions and atmospheric compositions over the ocean and urban-suburban environments. With the distributed surface sites the variability of atmospheric conditions are captured concurrently across a regional spatial scale. Some specific examples are given of comparisons of moisture and temperature correlative EDRs from the satellite sensors and surface based observations. An additional example is given of the use of this data to correct sea surface temperature (SST) retrieval biases from the hyperspectral IR satellite observations due to aerosol contamination.

Circumstellar dust in symbiotic novae

NASA Astrophysics Data System (ADS)

Jurkic, Tomislav; Kotnik-Karuza, Dubravka

2015-08-01

Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding evolution of symbiotic binaries. We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the long-term near-IR photometry, infrared ISO spectra and mid-IR interferometry. Pulsation properties and long-term variabilities were found from the near-IR light curves. The dust properties were determined using the DUSTY code which solves the radiative transfer. No changes in pulsational parameters were found, but a long-term variations with periods of 20-25 years have been detected which cannot be attributed to orbital motion.Circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel showed the presence of an optically thin CS dust envelope and an optically thick dust region outside the line of sight, which was further supported by the detailed modelling using the 2D LELUYA code. Obscuration events in RR Tel were explained by an increase in optical depth caused by the newly condensed dust leading to the formation of a compact dust shell. HM Sge showed permanent obscuration and a presence of a compact dust shell with a variable optical depth. Scattering of the near-IR colours can be understood by a change in sublimation temperature caused by the Mira variability. Presence of large dust grains (up to 4 µm) suggests an increased grain growth in conditions of increased mass loss. The mass loss rates of up to 17·10-6 MSun/yr were significantly higher than in intermediate-period single Miras and in agreement with longer-period O-rich AGB stars.Despite the nova outburst, HM Sge remained enshrouded in dust with no significant dust destruction. The existence of unperturbed dust shell suggests a small influence of the hot component and strong dust shielding from the UV flux. By the use of the CLOUDY code, we have showed that a high-density gas region can effectively stop most of the UV flux from the white dwarf and provide the observed dust shielding.

About possibility of temperature trace observing on a human skin through clothes by using computer processing of IR image

NASA Astrophysics Data System (ADS)

Trofimov, Vyacheslav A.; Trofimov, Vladislav V.; Shestakov, Ivan L.; Blednov, Roman G.

2017-05-01

One of urgent security problems is a detection of objects placed inside the human body. Obviously, for safety reasons one cannot use X-rays for such object detection widely and often. For this purpose, we propose to use THz camera and IR camera. Below we continue a possibility of IR camera using for a detection of temperature trace on a human body. In contrast to passive THz camera using, the IR camera does not allow to see very pronounced the object under clothing. Of course, this is a big disadvantage for a security problem solution based on the IR camera using. To find possible ways for this disadvantage overcoming we make some experiments with IR camera, produced by FLIR Company and develop novel approach for computer processing of images captured by IR camera. It allows us to increase a temperature resolution of IR camera as well as human year effective susceptibility enhancing. As a consequence of this, a possibility for seeing of a human body temperature changing through clothing appears. We analyze IR images of a person, which drinks water and eats chocolate. We follow a temperature trace on human body skin, caused by changing of temperature inside the human body. Some experiments are made with observing of temperature trace from objects placed behind think overall. Demonstrated results are very important for the detection of forbidden objects, concealed inside the human body, by using non-destructive control without using X-rays.

Pulsating stars in ω Centauri. Near-IR properties and period-luminosity relations

NASA Astrophysics Data System (ADS)

Navarrete, Camila; Catelan, Márcio; Contreras Ramos, Rodrigo; Alonso-García, Javier; Gran, Felipe; Dékány, István; Minniti, Dante

2017-09-01

ω Centauri (NGC 5139) contains many variable stars of different types, including the pulsating type II Cepheids, RR Lyrae and SX Phoenicis stars. We carried out a deep, wide-field, near-infrared (IR) variability survey of ω Cen, using the VISTA telescope. We assembled an unprecedented homogeneous and complete J and KS near-IR catalog of variable stars in the field of ω Cen. In this paper we compare optical and near-IR light curves of RR Lyrae stars, emphasizing the main differences. Moreover, we discuss the ability of near-IR observations to detect SX Phoenicis stars given the fact that the amplitudes are much smaller in these bands compared to the optical. Finally, we consider the case in which all the pulsating stars in the three different variability types follow a single period-luminosity relation in the near-IR bands.

Thermal diffusivity of electrical insulators at high temperatures: Evidence for diffusion of bulk phonon-polaritons at infrared frequencies augmenting phonon heat conduction

NASA Astrophysics Data System (ADS)

Hofmeister, Anne M.; Dong, Jianjun; Branlund, Joy M.

2014-04-01

We show that laser-flash analysis measurements of the temperature (T) dependence of thermal diffusivity (D) for diverse non-metallic (e.g., silicates) single-crystals is consistently represented by D(T) = FT-G + HT above 298 K, with G ranging from 0.3 to 2, depending on structure, and H being ˜10-4 K-1 for 51 single-crystals, 3 polycrystals, and two glasses unaffected by disorder or reconstructive phase transitions. Materials exhibiting this behavior include complex silicates with variable amounts of cation disorder, perovskite structured materials, and graphite. The high-temperature term HT becomes important by ˜1300 K, above which temperature its contribution to D(T) exceeds that of the FT-G term. The combination of the FT-G and HT terms produces the nearly temperature independent high-temperature region of D previously interpreted as the minimal phonon mean free path being limited by the finite interatomic spacing. Based on the simplicity of the fit and large number of materials it represents, this finding has repercussions for high-temperature models of heat transport. One explanation is that the two terms describing D(T) are associated with two distinct microscopic mechanisms; here, we explore the possibility that the thermal diffusivity of an electrical insulator could include both a contribution of lattice phonons (the FT-G term) and a contribution of diffusive bulk phonon-polaritons (BPP) at infrared (IR) frequencies (the HT term). The proposed BPP diffusion exists over length scales smaller than the laboratory sample sizes, and transfers mixed light and vibrational energy at a speed significantly smaller than the speed of light. Our diffusive IR-BPP hypothesis is consistent with other experimental observations such as polarization behavior, dependence of D on the number of IR peaks, and H = 0 for Ge and Si, which lack IR fundamentals. A simple quasi-particle thermal diffusion model is presented to begin understanding the contribution from bulk phonon-polaritons to overall heat conduction.

Recent Improvements in Estimating Convective and Stratiform Rainfall in Amazonia

NASA Technical Reports Server (NTRS)

Negri, Andrew J.

1999-01-01

In this paper we present results from the application of a satellite infrared (IR) technique for estimating rainfall over northern South America. Our main objectives are to examine the diurnal variability of rainfall and to investigate the relative contributions from the convective and stratiform components. We apply the technique of Anagnostou et al (1999). In simple functional form, the estimated rain area A(sub rain) may be expressed as: A(sub rain) = f(A(sub mode),T(sub mode)), where T(sub mode) is the mode temperature of a cloud defined by 253 K, and A(sub mode) is the area encompassed by T(sub mode). The technique was trained by a regression between coincident microwave estimates from the Goddard Profiling (GPROF) algorithm (Kummerow et al, 1996) applied to SSM/I data and GOES IR (11 microns) observations. The apportionment of the rainfall into convective and stratiform components is based on the microwave technique described by Anagnostou and Kummerow (1997). The convective area from this technique was regressed against an IR structure parameter (the Convective Index) defined by Anagnostou et al (1999). Finally, rainrates are assigned to the Am.de proportional to (253-temperature), with different rates for the convective and stratiform

Eddy Seeding in the Labrador Sea: a Submerged Autonomous Launching Platform (SALP) Application

NASA Astrophysics Data System (ADS)

Furey, Heather H.; Femke de Jong, M.; Bower, Amy S.

2013-04-01

A simplified Submerged Autonomous Launch Platform (SALP) was used to release profiling floats into warm-core Irminger Rings (IRs) in order to investigate their vertical structure and evolution in the Labrador Sea from September 2007 - September 2009. IRs are thought to play an important role in restratification after convection in the Labrador Sea. The SALP is designed to release surface drifters or subsurface floats serially from a traditional ocean mooring, using real-time ocean measurements as criteria for launch. The original prototype instrument used properties measured at multiple depths, with information relayed to the SALP controller via acoustic modems. In our application, two SALP carousels were attached at 500 meters onto a heavily-instrumented deep water mooring, in the path of recently-shed IRs off the west Greenland shelf. A release algorithm was designed to use temperature and pressure measured at the SALP depth only to release one or two APEX profiling drifters each time an IR passed the mooring, using limited historical observations to set release thresholds. Mechanically and electronically, the SALP worked well: out of eleven releases, there was only one malfunction when a float was caught in the cage after the burn-wire had triggered. However, getting floats trapped in eddies met with limited success due to problems with the release algorithm and float ballasting. Out of seven floats launched from the platform using oceanographic criteria, four were released during warm water events that were not related to passing IRs. Also, after float release, it took on average about 2.6 days for the APEX to adjust from its initial ballast depth, about 600 meters, to its park point of 300 meters, leaving the float below the trapped core of water in the IRs. The other mooring instruments (at depths of 100 to 3000 m), revealed that 12 IRs passed by the mooring in the 2-year monitoring period. With this independent information, we were able to assess and improve the release algorithm, still based on ocean conditions measured only at one depth. We found that much better performance could have been achieved with an algorithm that detected IRs based on a temperature difference from a long-term running mean rather than a fixed temperature threshold. This highlights the challenge of designing an appropriate release strategy with limited a priori information on the amplitude and time scales of the background variability.

Morphologies of mid-IR variability-selected AGN host galaxies

NASA Astrophysics Data System (ADS)

Polimera, Mugdha; Sarajedini, Vicki; Ashby, Matthew L. N.; Willner, S. P.; Fazio, Giovanni G.

2018-05-01

We use multi-epoch 3.6 and 4.5 μm data from the Spitzer Extended Deep Survey (SEDS) to probe the AGN population among galaxies to redshifts ˜3 via their mid-IR variability. About 1 per cent of all galaxies in our survey contain varying nuclei, 80 per cent of which are likely to be AGN. Twenty-three per cent of mid-IR variables are also X-ray sources. The mid-IR variables have a slightly greater fraction of weakly disturbed morphologies compared to a control sample of normal galaxies. The increased fraction of weakly distorted hosts becomes more significant when we remove the X-ray emitting AGN, while the frequency of strongly disturbed hosts remains similar to the control galaxy sample. These results suggest that mid-IR variability identifies a unique population of obscured, Compton-thick AGN revealing elevated levels of weak distortion among their host galaxies.

Greyscale Photolithography for Multilayer PZT Microelectromechanical Systems (MEMS) Device Applications

DTIC Science & Technology

We present development of a process to perform greyscale photolithography on a 2.55-m thick photoresist in order to transfer tiered and sloped...platinum or iridium oxide (IrO2) electrodes above and below each layer. Process variables including resist rehydration , focus of the exposure, and UV cure...bake temperature were optimized to produce the best greyscale profile through the thickness of the resist.

Improved VAS regression soundings of mesoscale temperature features observed during the atmospheric variability experiment on 6 March 1982. [VISSR Atmospheric Sounder

NASA Technical Reports Server (NTRS)

Chesters, Dennis; Keyser, Dennis A.; Larko, David E.; Uccellini, Louis W.

1988-01-01

In 1982, the VISSR Atmospheric Sounder (VAS) on the GOES satellite performed the Atmospheric Variability Experiment (AVE) to verify VAS's mesoscale-sounding capabilities. Attention is given to the AVE network in the late afternoon of March 6, 1982, after a winter storm had passed over Texas, in order to ascertain whether such temperature profile deviations from the average lapse rate as a midlevel cold pool (which should decrease the brightness of several IR channels) can be retrieved from VAS radiances. Two simple enhancements are introduced: the regression matrix is calculated using the AVE asynoptic radiosondes launched from NWS sites in the region, and a change of the statistical conditioning factor from the conservative 10/1 SNR to a more optimistic 100/1 for those VAS channels that are more sensitive to tropospheric temperature.

Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network-Cloud Classification System

NASA Astrophysics Data System (ADS)

Hong, Yang

Precipitation estimation from satellite information (VISIBLE , IR, or microwave) is becoming increasingly imperative because of its high spatial/temporal resolution and board coverage unparalleled by ground-based data. After decades' efforts of rainfall estimation using IR imagery as basis, it has been explored and concluded that the limitations/uncertainty of the existing techniques are: (1) pixel-based local-scale feature extraction; (2) IR temperature threshold to define rain/no-rain clouds; (3) indirect relationship between rain rate and cloud-top temperature; (4) lumped techniques to model high variability of cloud-precipitation processes; (5) coarse scales of rainfall products. As continuing studies, a new version of Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network (PERSIANN), called Cloud Classification System (CCS), has been developed to cope with these limitations in this dissertation. CCS includes three consecutive components: (1) a hybrid segmentation algorithm, namely Hierarchically Topographical Thresholding and Stepwise Seeded Region Growing (HTH-SSRG), to segment satellite IR images into separated cloud patches; (2) a 3D feature extraction procedure to retrieve both pixel-based local-scale and patch-based large-scale features of cloud patch at various heights; (3) an ANN model, Self-Organizing Nonlinear Output (SONO) network, to classify cloud patches into similarity-based clusters, using Self-Organizing Feature Map (SOFM), and then calibrate hundreds of multi-parameter nonlinear functions to identify the relationship between every cloud types and their underneath precipitation characteristics using Probability Matching Method and Multi-Start Downhill Simplex optimization techniques. The model was calibrated over the Southwest of United States (100°--130°W and 25°--45°N) first and then adaptively adjusted to the study region of North America Monsoon Experiment (65°--135°W and 10°--50°N) using observations from Geostationary Operational Environmental Satellite (GOES) IR imagery, Next Generation Radar (NEXRAD) rainfall network, and Tropical Rainfall Measurement Mission (TRMM) microwave rain rate estimates. CCS functions as a distributed model that first identifies cloud patches and then dispatches different but the best matching cloud-precipitation function for each cloud patch to estimate instantaneous rain rate at high spatial resolution (4km) and full temporal resolution of GOES IR images (every 30-minute). Evaluated over a range of spatial and temporal scales, the performance of CCS compared favorably with GOES Precipitation Index (GPI), Universal Adjusted GPI (UAGPI), PERSIANN, and Auto-Estimator (AE) algorithms, consistently. Particularly, the large number of nonlinear functions and optimum IR-rain rate thresholds of CCS model are highly variable, reflecting the complexity of dominant cloud-precipitation processes from cloud patch to cloud patch over various regions. As a result, CCS can more successfully capture variability in rain rate at small scales than existing algorithms and potentially provides rainfall product from GOES IR-NEXARD-TRMM TMI (SSM/I) at 0.12° x 0.12° and 3-hour resolution with relative low standard error (˜=3.0mm/hr) and high correlation coefficient (˜=0.65).

Spatial and Temporal Variabilities of Solar and Longwave Radiation Fluxes below a Coniferous Forest in the French Alps

NASA Astrophysics Data System (ADS)

Sicart, J. E.; Ramseyer, V.; Lejeune, Y.; Essery, R.; Webster, C.; Rutter, N.

2017-12-01

At high altitudes and latitudes, snow has a large influence on hydrological processes. Large fractions of these regions are covered by forests, which have a strong influence on snow accumulation and melting processes. Trees absorb a large part of the incoming shortwave radiation and this heat load is mostly dissipated as longwave radiation. Trees shelter the snow surface from wind, so sub-canopy snowmelt depends mainly on the radiative fluxes: vegetation attenuates the transmission of shortwave radiation but enhances longwave irradiance to the surface. An array of 13 pyranometers and 11 pyrgeometers was deployed on the snow surface below a coniferous forest at the CEN-MeteoFrance Col de Porte station in the French Alps (1325 m asl) during the 2017 winter in order to investigate spatial and temporal variabilities of solar and infrared irradiances in different meteorological conditions. Sky view factors measured with hemispherical photographs at each radiometer location were in a narrow range from 0.2 to 0.3. The temperature of the vegetation was measured with IR thermocouples and an IR camera. In clear sky conditions, the attenuation of solar radiation by the canopy reached 96% and its spatial variability exceeded 100 W m-2. Longwave irradiance varied by 30 W m-2 from dense canopy to gap areas. In overcast conditions, the spatial variabilities of solar and infrared irradiances were reduced and remained closely related to the sky view factor. A simple radiative model taking into account the penetration through the canopy of the direct and diffuse solar radiation, and isotropic infrared emission of the vegetation as a blackbody emitter, accurately reproduced the dynamics of the radiation fluxes at the snow surface. Model results show that solar transmissivity of the canopy in overcast conditions is an excellent proxy of the sky view factor and the emitting temperature of the vegetation remained close to the air temperature in this typically dense Alpine forest.

Delineation of soil temperature regimes from HCMM data

NASA Technical Reports Server (NTRS)

Day, R. L.; Petersen, G. W. (Principal Investigator)

1982-01-01

The subsetting of HCMM data into ORSER format was completed for four dates using a modified SUBSET program. Large areas (approximately 2500 scan lines, 1680 elements) were selected to increase the occurrence of suitable control points for registration. Average daily temperatures (ADT) were calculated for each date. The MERGE program combined registered daytime temperature (DAY-IR) with nighttime temperature (NIGHT-IR) to form a separate two-channel data set. The SUBTRAN program averaged the DAY-IR and NIGHT-IR creating a third ADT channel. Registration equations for the four ADT data sets were generated. A one dimensional soil heat flow equation was modified to allow for mean annual soil temperature predictions using merged ADT data sets.

Non-contact local temperature measurement inside an object using an infrared point detector

NASA Astrophysics Data System (ADS)

Hisaka, Masaki

2017-04-01

Local temperature measurement in deep areas of objects is an important technique in biomedical measurement. We have investigated a non-contact method for measuring temperature inside an object using a point detector for infrared (IR) light. An IR point detector with a pinhole was constructed and the radiant IR light emitted from the local interior of the object is photodetected only at the position of pinhole located in imaging relation. We measured the thermal structure of the filament inside the miniature bulb using the IR point detector, and investigated the temperature dependence at approximately human body temperature using a glass plate positioned in front of the heat source.

Infrared and Passive Microwave Radiometric Sea Surface Temperatures and Their Relationships to Atmospheric Forcing

NASA Technical Reports Server (NTRS)

Castro, Sandra L.

2004-01-01

The current generation of infrared (IR) and passive microwave (MW) satellite sensors provides highly complementary information for monitoring sea surface temperature (SST). On the one hand, infrared sensors provide high resolution and high accuracy but are obscured by clouds. Microwave sensors on the other hand, provide coverage through non-precipitating clouds but have coarser resolution and generally poorer accuracy. Assuming that the satellite SST measurements do not have spatially variable biases, they can be blended combining the merits of both SST products. These factors have motivated recent work in blending the MW and IR data in an attempt to produce high-accuracy SST products with improved coverage in regions with persistent clouds. The primary sources of retrieval uncertainty are, however, different for the two sensors. The main uncertainty in the MW retrievals lies in the effects of wind-induced surface roughness and foam on emissivity, whereas the IR retrievals are more sensitive to the atmospheric water vapor and aerosol content. Average nighttime differences between the products for the month periods of January 1999 and June 2000 are shown. These maps show complex spatial and temporal differences as indicated by the strong spatially coherent features in the product differences and the changes between seasons. Clearly such differences need to be understood and accounted for if the products are to be combined. The overall goals of this project are threefold: (1) To understand the sources of uncertainty in the IR and MW SST retrievals and to characterize the errors affecting the two types of retrieval as a fiction of atmospheric forcing; (2) To demonstrate how representative the temperature difference between the two satellite products is of Delta T; (3) To apply bias adjustments and to device a comprehensive treatment of the behavior of the temperature difference across the oceanic skin layer to determine the best method for blending thermal infrared and passive microwave measurements of SSTs.

Variations in Upper-Tropospheric Humidity and Convective Processes as Seen from SSM/T-2

NASA Technical Reports Server (NTRS)

Robertson, Franklin R.; Fitzjarrald, Dan E.

2007-01-01

Water vapor feedback, particularly involving water vapor in the upper troposphere (UTH), is widely regarded as the process with the most potential to amplify anthropogenic greenhouse forcing. Yet, our ability to quantify observationally water vapor variations in the current climate and the relationships to convective processes remains rather crude. Remote sensing from polar orbiting instruments has played a major role in documenting UTH variability, supplementing highly undersampled and poorly calibrated rawinsonde measurements. Most of our observational understanding of UTH has come from the 6.7 micrometer channel measurements which are subject to cloud contamination uncertainties. In this work we examine UTH variations present in the Special Sensor Microwave Temperature Sounder 2 (SSM/T-2) sensors flying aboard Defense Military Satellite Program (DMSP) polar orbiting satellites during the period 1993 through 2001. We employ data from the the 183.3 +/- 1 GHz channel which is far less sensitive to cirrus than IR methods. Our primary focus is on obtaining more reliable statistics of interannual behavior; i.e. How close to constant RH are interannual variations in T2 UTH over the tropics? How do temperature and moisture variations contribute regionally? The 1997/1998 strong ENS0 warming event and adjacent cool periods provide a strong signal to study, albeit a perturbation of natural climate variability. Modeling the 183.3 GHz channel using reanalysis temperature data, but with climatological water vapor, allows us to infer the separate contribution by water vapor in the observations. In addition, frozen hydrometeors produced by deep convection are also captured in the 150 GHz oxygen channel, providing an opportUnity to relate the incidence of deep convection to water vapor variability. Our results indicate a much larger variation of 183.3 GHz brightness temperatures would be observed were it not for water vapor variations positively correlated with tropical SSTs. Comparisons are made with previous studies using both IR and microwave observations to characterize UTH response to tropical SSTs.

Long-term infrared monitoring of stellar sources from earth orbit

NASA Technical Reports Server (NTRS)

Maran, S. P.; Heinsheimer, T. F.; Stocker, T. L.; Anand, S. P. S.; Chapman, R. D.; Hobbs, R. W.; Michalitsanos, A. G.; Wright, F. H.; Kipp, S. L.

1976-01-01

A program is discussed which involved monitoring the photometric activity of 18 bright variable IR stars at 2.7 microns with satellite- and rocket-borne instrumentation in the period from 1971 to 1975. The stellar sample includes 3 Lb variables, 8 semiregular variables, 5 Mira-type variables, and 2 previously unknown and unclassified IR variables. Detailed light curves of many of these stars were determined for intervals of 3 yr or more; spectra from 2.7 to 20 microns were constructed for nine of them using data obtained entirely with instruments above the atmosphere. Photometric IR light curves and other data are presented for SW Virginis, R Aquilae, S Scuti, IRC 00265, RT Hydrae, S Orionis, S Canis Minoris, Omicron Ceti, and R Leonis. Several hypotheses concerning the interpretation of the IR data are examined.

Drosophila Ionotropic Receptor 25a mediates circadian clock resetting by temperature.

PubMed

Chen, Chenghao; Buhl, Edgar; Xu, Min; Croset, Vincent; Rees, Johanna S; Lilley, Kathryn S; Benton, Richard; Hodge, James J L; Stanewsky, Ralf

2015-11-26

Circadian clocks are endogenous timers adjusting behaviour and physiology with the solar day. Synchronized circadian clocks improve fitness and are crucial for our physical and mental well-being. Visual and non-visual photoreceptors are responsible for synchronizing circadian clocks to light, but clock-resetting is also achieved by alternating day and night temperatures with only 2-4 °C difference. This temperature sensitivity is remarkable considering that the circadian clock period (~24 h) is largely independent of surrounding ambient temperatures. Here we show that Drosophila Ionotropic Receptor 25a (IR25a) is required for behavioural synchronization to low-amplitude temperature cycles. This channel is expressed in sensory neurons of internal stretch receptors previously implicated in temperature synchronization of the circadian clock. IR25a is required for temperature-synchronized clock protein oscillations in subsets of central clock neurons. Extracellular leg nerve recordings reveal temperature- and IR25a-dependent sensory responses, and IR25a misexpression confers temperature-dependent firing of heterologous neurons. We propose that IR25a is part of an input pathway to the circadian clock that detects small temperature differences. This pathway operates in the absence of known 'hot' and 'cold' sensors in the Drosophila antenna, revealing the existence of novel periphery-to-brain temperature signalling channels.

Hydrogen storage and evolution catalysed by metal hydride complexes.

PubMed

Fukuzumi, Shunichi; Suenobu, Tomoyoshi

2013-01-07

The storage and evolution of hydrogen are catalysed by appropriate metal hydride complexes. Hydrogenation of carbon dioxide by hydrogen is catalysed by a [C,N] cyclometalated organoiridium complex, [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(OH(2))](2)SO(4) [Ir-OH(2)](2)SO(4), under atmospheric pressure of H(2) and CO(2) in weakly basic water (pH 7.5) at room temperature. The reverse reaction, i.e., hydrogen evolution from formate, is also catalysed by [Ir-OH(2)](+) in acidic water (pH 2.8) at room temperature. Thus, interconversion between hydrogen and formic acid in water at ambient temperature and pressure has been achieved by using [Ir-OH(2)](+) as an efficient catalyst in both directions depending on pH. The Ir complex [Ir-OH(2)](+) also catalyses regioselective hydrogenation of the oxidised form of β-nicotinamide adenine dinucleotide (NAD(+)) to produce the 1,4-reduced form (NADH) under atmospheric pressure of H(2) at room temperature in weakly basic water. In weakly acidic water, the complex [Ir-OH(2)](+) also catalyses the reverse reaction, i.e., hydrogen evolution from NADH to produce NAD(+) at room temperature. Thus, interconversion between NADH (and H(+)) and NAD(+) (and H(2)) has also been achieved by using [Ir-OH(2)](+) as an efficient catalyst and by changing pH. The iridium hydride complex formed by the reduction of [Ir-OH(2)](+) by H(2) and NADH is responsible for the hydrogen evolution. Photoirradiation (λ > 330 nm) of an aqueous solution of the Ir-hydride complex produced by the reduction of [Ir-OH(2)](+) with alcohols resulted in the quantitative conversion to a unique [C,C] cyclometalated Ir-hydride complex, which can catalyse hydrogen evolution from alcohols in a basic aqueous solution (pH 11.9). The catalytic mechanisms of the hydrogen storage and evolution are discussed by focusing on the reactivity of Ir-hydride complexes.

The near-infrared broad emission line region of active galactic nuclei - II. The 1-μm continuum

NASA Astrophysics Data System (ADS)

Landt, Hermine; Elvis, Martin; Ward, Martin J.; Bentz, Misty C.; Korista, Kirk T.; Karovska, Margarita

2011-06-01

We use quasi-simultaneous near-infrared (near-IR) and optical spectroscopy from four observing runs to study the continuum around 1 μm in 23 well-known broad emission line active galactic nuclei (AGN). We show that, after correcting the optical spectra for host galaxy light, the AGN continuum around this wavelength can be approximated by the sum of mainly two emission components, a hot dust blackbody and an accretion disc. The accretion disc spectrum appears to dominate the flux at ˜ 1 μm, which allows us to derive a relation for estimating AGN black hole masses based on the near-IR virial product. This result also means that a near-IR reverberation programme can determine the AGN state independent of simultaneous optical spectroscopy. On average we derive hot dust blackbody temperatures of ˜1400 K, a value close to the sublimation temperature of silicate dust grains, and relatively low hot dust covering factors of ˜7 per cent. Our preliminary variability studies indicate that in most sources, the hot dust emission responds to changes in the accretion disc flux with the expected time lag; however, a few sources show a behaviour that can be attributed to dust destruction.

Variability of the Labrador Sea Surface Eddy Kinetic Energy Observed by Altimeter From 1993 to 2012

NASA Astrophysics Data System (ADS)

Zhang, Weiwei; Yan, Xiao-Hai

2018-01-01

A merged along track altimeter data set is used to study the variability of eddy kinetic energy (EKE) in the Labrador Sea from 1993 to 2012. The EKE near the west Greenland current (WGC) has strong interannual variability without long-term trend from 1993 to 2012. The propagation direction of the Irminger Rings (IRs) originating from the WGC can be inferred from the EKE derived from altimeter, and the southward propagation of the IRs varies interannually. The central Labrador Sea EKE increases significantly from 1993 to 2012. The central Labrador Sea temperature difference between the end and the beginning of the winter convections is defined as restratification index to measure the restratification strengths. The relation between the central Labrador Sea EKE and the restratification index shows that the enhanced eddy activity originating from the west of the central Labrador Sea may cool the central Labrador Sea significantly. The interannual variability of the WGC EKE is likely to be driven by the large scale Subpolar Gyre (SPG) circulation variability and the North Atlantic Oscillation (NAO). The NAO also affects the central Labrador Sea EKE through its fingerprint in the local wind stress and surface heat flux. The NAO affects the WGC EKE by changing the SPG circulation strength, which will subsequently affect the WGC EKE through unknown physical processes.

Investigation of thermal effects of infrared lasers on the rabbit retina: a study in the course of development of an active subretinal prosthesis.

PubMed

Sailer, Heiko; Shinoda, Kei; Blatsios, Georgios; Kohler, Konrad; Bondzio, Lars; Zrenner, Eberhart; Gekeler, Florian

2007-08-01

Retinal implants are intended to replace photoreceptors in patients suffering from degenerative retinal diseases such as retinitis pigmentosa. Data show that photodiodes in subretinal implants are not powerful enough to stimulate overlying retinal tissue by simply transforming light energy into electrical energy. Therefore, infrared (IR) irradiation has been envisioned to supply additional energy. While epiretinal implants mostly use induction coils for wireless energy transfer, IR irradiation seems to be an additional option. This study investigated the feasibility of an IR energy supply for an active subretinal implant by assessing thermal effects of IR irradiation onto the rabbit retina. Polyimide foil strips carrying an optical sensor as well as a thermal sensor were implanted into the subretinal space of the eyes of nine rabbits using a transchoroidal surgical approach. The area of the thermal sensor was irradiated by an IR laser (830 nm) focused on the device. The sensor provided simultaneous real-time measurements of absolute temperature and irradiation density, allowing direct correlation of the temperature increase to different intensities of IR irradiation. Possible IR-related damage to the retina was examined in histological sections. Temperature changes in living and dead animals were evaluated as a function of IR irradiation power of between 0.1 mW and 40 mW (0.03 mW/mm2-12.7 mW/mm2). We found an exponential relationship between IR irradiation power and temperature increase over the whole range (up to 12.7 mW/mm2) in the living animal. The maximum temperature increase caused by IR irradiation of 40 mW (12.7 mW/mm2) was 4.5 degrees C. The ratio of temperature increase to IR irradiation density postmortem (i.e., without ocular blood flow) was linear over the whole range, with 1.15 degrees C per 1 mW/mm2. Thus, the cooling effect of ocular blood flow varied depending on IR irradiance density. In histological sections, no IR-induced damage to the retina was detected. A temperature increase of 3.2 degrees C in the living rabbit eye is to be expected when powering a subretinal implant with 15 mW (4.8 mW/mm2) IR power, the wattage used in an external power supply for an active implant with 1,500 electrodes. This appears to be a tolerable increase for ocular tissue.

Use of near infrared/red radiance ratios for estimating vegetation biomass and physiological status

NASA Technical Reports Server (NTRS)

Tucker, C. J.

1977-01-01

The application of photographic infrared/red (ir/red) reflectance or radiance ratios for the estimation of vegetation biomass and physiological status were investigated by analyzing in situ spectral reflectance data from experimental grass plots. Canopy biological samples were taken for total wet biomass, total dry biomass, leaf water content, dry green biomass, dry brown biomass, and total chlorophyll content at each sampling date. Integrated red and photographic infrared radiances were regressed against the various canopy or plot variables to determine the relative significance between the red, photographic infrared, and the ir/red ratio and the canopy variables. The ir/red ratio is sensitive to the photosynthetically active or green biomass, the rate of primary production, and actually measures the interaction between the green biomass and the rate of primary production within a given species type. The ir/red ratio resulted in improved regression significance over the red or the ir/radiances taken separately. Only slight differences were found between ir/red ratio, the ir-red difference, the vegetation index, and the transformed vegetation index. The asymptotic spectral radiance properties of the ir, red, ir/red ratio, and the various transformations were evaluated.

More than meets the IR: the expanding roles of variant Ionotropic Glutamate Receptors in sensing odor, taste, temperature and moisture.

PubMed

van Giesen, Lena; Garrity, Paul A

2017-01-01

The ionotropic receptors (IRs) are a branch of the ionotropic glutamate receptor family and serve as important mediators of sensory transduction in invertebrates. Recent work shows that, though initially studied as olfactory receptors, the IRs also mediate the detection of taste, temperature, and humidity. Here, we summarize recent insights into IR evolution and its potential ecological significance as well as recent advances in our understanding of how IRs contribute to diverse sensory modalities.

More than meets the IR: the expanding roles of variant Ionotropic Glutamate Receptors in sensing odor, taste, temperature and moisture

PubMed Central

van Giesen, Lena; Garrity, Paul A.

2017-01-01

The ionotropic receptors (IRs) are a branch of the ionotropic glutamate receptor family and serve as important mediators of sensory transduction in invertebrates. Recent work shows that, though initially studied as olfactory receptors, the IRs also mediate the detection of taste, temperature, and humidity. Here, we summarize recent insights into IR evolution and its potential ecological significance as well as recent advances in our understanding of how IRs contribute to diverse sensory modalities. PMID:29034089

A Continued Census of Mid-IR Variability from ULXs

NASA Astrophysics Data System (ADS)

Lau, Ryan; Kasliwal, Mansi; Heida, Marianne; Walton, Dom

2017-04-01

The nature of ultraluminous X-ray sources (ULXs) that radiate at luminosities >10^39 erg/s is still a mystery. ULXs are believed to be binaries with an accreting compact object and stellar mass-donor companion, but such high luminosities require accretion rates that are factors of 100 greater than the Eddington limit for accretion onto a neutron star or stellar mass black hole. The difficulties in interpreting ULXs are largely attributed to current observational challenges in determining their orbital properties as well as the properties of the mass-donor companion. Recently, near- and mid-infrared (IR) observations have been demonstrated as powerful diagnostics of the mass-donor companion and the circumstellar environment of ULXs. For example, serendipitous Spitzer/IRAC observations of the ULX Holmberg II X-1 in our Spitzer Infrared Intensive Transients Survey (SPIRITS) revealed the first detection of mid-IR variability from a ULX, where we claimed that the mid-IR emission arises from a dusty circumbinary torus in the winds of a supergiant B[e] mass-donor companion. We identified 5 additional mid-IR ULX counterparts detected by Spitzer/IRAC, one of which shows significant variability like Holmberg II X-1. Although we are finding a growing sample of ULXs exhibiting mid-IR variability, it is unclear what causes it. Notably, the week - year cadence baselines of the SPIRITS observations are inadequate for resolving variability timescales consistent with several observed ULX orbital periods. In this proposal, we request time-series observations of 6 ULXs with cadence baselines ranging from 0.5 days to 1 week in order to identify the timescales associated mid-IR variability.

Unusual island formations of Ir on Ge (111) studied by STM

NASA Astrophysics Data System (ADS)

van Zijll, M.; Huffman, E.; Lovinger, D. J.; Chiang, S.

2017-12-01

Island formation on the Ir/Ge(111) surface is studied using ultrahigh vacuum scanning tunneling microscopy. Ir was deposited at room temperature onto a Ge (111) substrate with coverages between 0.5 and 2.0 monolayers (ML). The samples were annealed to temperatures between 550 and 800 K, and then cooled prior to imaging. With 1.0 ML Ir coverage, at annealing temperatures 650-750 K, round islands form at locations where domain boundaries of the substrate reconstruction intersect. Both the substrate and the islands display a (√{ 3} x√{ 3}) R30∘ reconstruction. Additionally, a novel surface formation is observed where the Ir gathers along the antiphase domain boundaries between competing surface domains of the Ge surface reconstruction. This gives the appearance of the Ir in the domain boundaries forming pathways between different islands. The islands formed at higher annealing temperatures resulted in larger island sizes, which is evidence of Ostwald ripening. We present a model for the islands and the pathways which is consistent with our observations.

A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy

NASA Astrophysics Data System (ADS)

Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

2014-08-01

The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup.

A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy.

PubMed

Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

2014-08-01

The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup.

High temperature Ir segregation in Ir-B ceramics: Effect of oxygen presence on stability of IrB 2 and other Ir-B phases

DOE PAGES

Xie, Zhilin; Terracciano, Anthony C.; Cullen, David A.; ...

2015-05-13

The formation of IrB 2, IrB 1.35, IrB 1.1 and IrB monoboride phases in the Ir–B ceramic nanopowder was confirmed during mechanochemical reaction between metallic Ir and elemental B powders. The Ir–B phases were analysed after 90 h of high energy ball milling and after annealing of the powder for 72 h at 1050°C in vacuo. The iridium monoboride (IrB) orthorhombic phase was synthesised experimentally for the first time and identified by powder X-ray diffraction. Additionally, the ReB 2 type IrB 2 hexagonal phase was also produced for the first time and identified by high resolution transmission electron microscope. Irmore » segregation along disordered domains of the boron lattice was found to occur during high temperature annealing. Furthermore, these nanodomains may have useful catalytic properties.« less

L-cysteine-derived ambidextrous gelators of aromatic solvents and ethanol/water mixtures.

PubMed

Pal, Amrita; Dey, Joykrishna

2013-02-19

A series of L-cysteine-derived double hydrocarbon chain amphiphilic gelators L-(3-alkyl-carbamoylsulfanyl)-2-(3-alkylurido)propionic acid with different hydrocarbon chain lengths (C6-C16) was designed and synthesized. These gelators efficiently gelate only aromatic solvents. The gelation ability increased with the increase of chain length up to C14, but then it dropped with further increase of chain length. The C12 and C14 derivatives also gelled ethanol/water mixtures. The gels were characterized by a number of methods, including FT-IR, NMR, and XRD spectroscopy, electron microscopy, and rheology. The amphiphiles were observed to form either flat lamellar or ribbonlike aggregates in aromatic solvents as well as in ethanol/water mixtures. The gelation in all the solvents employed was observed to be thermoreversible. The gel-to-sol transition temperature as well as mechanical strength of the organogels were observed to increase with the hydrocarbon chain length. Both types of gels of C8-C16 amphiphiles have gel-to-sol transition temperatures above the physiological temperature (310 K). FT-IR and variable temperature (1)H NMR measurements suggested that van der Waals interactions have major contribution in the gelation process. The gel-to-sol transition temperature and mechanical strength of the organogels in ethanol/water mixtures was observed to be higher than those of benzene organogel.

A Method for Obtaining High Frequency, Global, IR-Based Convective Cloud Tops for Studies of the TTL

NASA Technical Reports Server (NTRS)

Pfister, Leonhard; Ueyama, Rei; Jensen, Eric; Schoeberl, Mark

2017-01-01

Models of varying complexity that simulate water vapor and clouds in the Tropical Tropopause Layer (TTL) show that including convection directly is essential to properly simulating the water vapor and cloud distribution. In boreal winter, for example, simulations without convection yield a water vapor distribution that is too uniform with longitude, as well as minimal cloud distributions. Two things are important for convective simulations. First, it is important to get the convective cloud top potential temperature correctly, since unrealistically high values (reaching above the cold point tropopause too frequently) will cause excessive hydration of the stratosphere. Second, one must capture the time variation as well, since hydration by convection depends on the local relative humidity (temperature), which has substantial variation on synoptic time scales in the TTL. This paper describes a method for obtaining high frequency (3-hourly) global convective cloud top distributions which can be used in trajectory models. The method uses rainfall thresholds, standard IR brightness temperatures, meteorological temperature analyses, and physically realistic and documented corrections IR brightness temperature corrections to derive cloud top altitudes and potential temperatures. The cloud top altitudes compare well with combined CLOUDSAT and CALIPSO data, both in time-averaged overall vertical and horizontal distributions and in individual cases (correlations of .65-.7). An important finding is that there is significant uncertainty (nearly .5 km) in evaluating the statistical distribution of convective cloud tops even using lidar. Deep convection whose tops are in regions of high relative humidity (such as much of the TTL), will cause clouds to form above the actual convection. It is often difficult to distinguish these clouds from the actual convective cloud due to the uncertainties of evaluating ice water content from lidar measurements. Comparison with models show that calculated cloud top altitudes are generally higher than those calculated by global analyses (e.g., MERRA). Interannual variability in the distribution of convective cloud top altitudes is also investigated.

Skin Temperature Processes in the Presence of Sea Ice

NASA Astrophysics Data System (ADS)

Brumer, S. E.; Zappa, C. J.; Brown, S.; McGillis, W. R.; Loose, B.

2013-12-01

Monitoring the sea-ice margins of polar oceans and understanding the physical processes at play at the ice-ocean-air interface is essential in the perspective of a changing climate in which we face an accelerated decline of ice caps and sea ice. Remote sensing and in particular InfraRed (IR) imaging offer a unique opportunity not only to observe physical processes at sea-ice margins, but also to measure air-sea exchanges near ice. It permits monitoring ice and ocean temperature variability, and can be used for derivation of surface flow field allowing investigating turbulence and shearing at the ice-ocean interface as well as ocean-atmosphere gas transfer. Here we present experiments conducted with the aim of gaining an insight on how the presence of sea ice affects the momentum exchange between the atmosphere and ocean and investigate turbulence production in the interplay of ice-water shear, convection, waves and wind. A set of over 200 high resolution IR imagery records was taken at the US Army Cold Regions Research and Engineering Laboratory (CRREL, Hanover NH) under varying ice coverage, fan and pump settings. In situ instruments provided air and water temperature, salinity, subsurface currents and wave height. Air side profiling provided environmental parameters such as wind speed, humidity and heat fluxes. The study aims to investigate what can be gained from small-scale high-resolution IR imaging of the ice-ocean-air interface; in particular how sea ice modulates local physics and gas transfer. The relationship between water and ice temperatures with current and wind will be addressed looking at the ocean and ice temperature variance. Various skin temperature and gas transfer parameterizations will be evaluated at ice margins under varying environmental conditions. Furthermore the accuracy of various techniques used to determine surface flow will be assessed from which turbulence statistics will be determined. This will give an insight on how ice presence may affect the dissipation of turbulent kinetic energy.

About possibility of temperature trace observing on the human skin using commercially available IR camera

NASA Astrophysics Data System (ADS)

Trofimov, Vyacheslav A.; Trofimov, Vladislav V.; Shestakov, Ivan L.; Blednov, Roman G.

2016-09-01

One of urgent security problems is a detection of objects placed inside the human body. Obviously, for safety reasons one cannot use X-rays for such object detection widely and often. Three years ago, we have demonstrated principal possibility to see a temperature trace, induced by food eating or water drinking, on the human body skin by using a passive THz camera. However, this camera is very expensive. Therefore, for practice it will be very convenient if one can use the IR camera for this purpose. In contrast to passive THz camera using, the IR camera does not allow to see the object under clothing, if an image, produced by this camera, is used directly. Of course, this is a big disadvantage for a security problem solution based on the IR camera using. To overcome this disadvantage we develop novel approach for computer processing of IR camera images. It allows us to increase a temperature resolution of IR camera as well as increasing of human year effective susceptibility. As a consequence of this, a possibility for seeing of a human body temperature changing through clothing appears. We analyze IR images of a person, which drinks water and eats chocolate. We follow a temperature trace on human body skin, caused by changing of temperature inside the human body. Some experiments were made with measurements of a body temperature covered by T-shirt. Shown results are very important for the detection of forbidden objects, cancelled inside the human body, by using non-destructive control without using X-rays.

Micro-spatial distribution of malaria cases and control strategies at ward level in Gwanda district, Matabeleland South, Zimbabwe.

PubMed

Manyangadze, Tawanda; Chimbari, Moses J; Macherera, Margaret; Mukaratirwa, Samson

2017-11-21

Although there has been a decline in the number of malaria cases in Zimbabwe since 2010, the disease remains the biggest public health threat in the country. Gwanda district, located in Matabeleland South Province of Zimbabwe has progressed to the malaria pre-elimination phase. The aim of this study was to determine the spatial distribution of malaria incidence at ward level for improving the planning and implementation of malaria elimination in the district. The Poisson purely spatial model was used to detect malaria clusters and their properties, including relative risk and significance levels at ward level. The geographically weighted Poisson regression (GWPR) model was used to explore the potential role and significance of environmental variables [rainfall, minimum and maximum temperature, altitude, Enhanced Vegetation Index (EVI), Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), rural/urban] and malaria control strategies [indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLINs)] on the spatial patterns of malaria incidence at ward level. Two significant clusters (p < 0.05) of malaria cases were identified: (1) ward 24 south of Gwanda district and (2) ward 9 in the urban municipality, with relative risks of 5.583 and 4.316, respectively. The semiparametric-GWPR model with both local and global variables had higher performance based on AICc (70.882) compared to global regression (74.390) and GWPR which assumed that all variables varied locally (73.364). The semiparametric-GWPR captured the spatially non-stationary relationship between malaria cases and minimum temperature, NDVI, NDWI, and altitude at the ward level. The influence of LLINs, IRS and rural or urban did not vary and remained in the model as global terms. NDWI (positive coefficients) and NDVI (range from negative to positive coefficients) showed significant association with malaria cases in some of the wards. The IRS had a protection effect on malaria incidence as expected. Malaria incidence is heterogeneous even in low-transmission zones including those in pre-elimination phase. The relationship between malaria cases and NDWI, NDVI, altitude, and minimum temperature may vary at local level. The results of this study can be used in planning and implementation of malaria control strategies at district and ward levels.

Infrared Sensor-Based Temperature Control for Domestic Induction Cooktops

PubMed Central

Lasobras, Javier; Alonso, Rafael; Carretero, Claudio; Carretero, Enrique; Imaz, Eduardo

2014-01-01

In this paper, a precise real-time temperature control system based on infrared (IR) thermometry for domestic induction cooking is presented. The temperature in the vessel constitutes the control variable of the closed-loop power control system implemented in a commercial induction cooker. A proportional-integral controller is applied to establish the output power level in order to reach the target temperature. An optical system and a signal conditioning circuit have been implemented. For the signal processing a microprocessor with 12-bit ADC and a sampling rate of 1 Ksps has been used. The analysis of the contributions to the infrared radiation permits the definition of a procedure to estimate the temperature of the vessel with a maximum temperature error of 5 °C in the range between 60 and 250 °C for a known cookware emissivity. A simple and necessary calibration procedure with a black-body sample is presented. PMID:24638125

Infrared sensor-based temperature control for domestic induction cooktops.

PubMed

Lasobras, Javier; Alonso, Rafael; Carretero, Claudio; Carretero, Enrique; Imaz, Eduardo

2014-03-14

In this paper, a precise real-time temperature control system based on infrared (IR) thermometry for domestic induction cooking is presented. The temperature in the vessel constitutes the control variable of the closed-loop power control system implemented in a commercial induction cooker. A proportional-integral controller is applied to establish the output power level in order to reach the target temperature. An optical system and a signal conditioning circuit have been implemented. For the signal processing a microprocessor with 12-bit ADC and a sampling rate of 1 Ksps has been used. The analysis of the contributions to the infrared radiation permits the definition of a procedure to estimate the temperature of the vessel with a maximum temperature error of 5 °C in the range between 60 and 250 °C for a known cookware emissivity. A simple and necessary calibration procedure with a black-body sample is presented.

Modeling and Compensating Temperature-Dependent Non-Uniformity Noise in IR Microbolometer Cameras

PubMed Central

Wolf, Alejandro; Pezoa, Jorge E.; Figueroa, Miguel

2016-01-01

Images rendered by uncooled microbolometer-based infrared (IR) cameras are severely degraded by the spatial non-uniformity (NU) noise. The NU noise imposes a fixed-pattern over the true images, and the intensity of the pattern changes with time due to the temperature instability of such cameras. In this paper, we present a novel model and a compensation algorithm for the spatial NU noise and its temperature-dependent variations. The model separates the NU noise into two components: a constant term, which corresponds to a set of NU parameters determining the spatial structure of the noise, and a dynamic term, which scales linearly with the fluctuations of the temperature surrounding the array of microbolometers. We use a black-body radiator and samples of the temperature surrounding the IR array to offline characterize both the constant and the temperature-dependent NU noise parameters. Next, the temperature-dependent variations are estimated online using both a spatially uniform Hammerstein-Wiener estimator and a pixelwise least mean squares (LMS) estimator. We compensate for the NU noise in IR images from two long-wave IR cameras. Results show an excellent NU correction performance and a root mean square error of less than 0.25 ∘C, when the array’s temperature varies by approximately 15 ∘C. PMID:27447637

Noncontact localized internal infrared radiation measurement using an infrared point detector

NASA Astrophysics Data System (ADS)

Hisaka, Masaki

2017-12-01

The techniques for temperature measurement within the human body are important for clinical applications. A method for noncontact local infrared (IR) radiation measurements was investigated deep within an object to simulate how the core human body temperature can be obtained. To isolate the IR light emitted from a specific area within the object from the external noise, the radiating IR light was detected using an IR point detector, which comprises a pinhole and a thermopile positioned at an imaging relation with the region of interest within the object. The structure of the helical filament radiating IR light inside a light bulb was thermally imaged by scanning the bulb in two dimensions. Moreover, this approach was used to effectively measure IR light in the range of human body temperature using a glass plate placed in front of the heat source, mimicking the ocular fundus.

Infrared Imaging Tools for Diagnostic Applications in Dermatology.

PubMed

Gurjarpadhye, Abhijit Achyut; Parekh, Mansi Bharat; Dubnika, Arita; Rajadas, Jayakumar; Inayathullah, Mohammed

Infrared (IR) imaging is a collection of non-invasive imaging techniques that utilize the IR domain of the electromagnetic spectrum for tissue assessment. A subset of these techniques construct images using back-reflected light, while other techniques rely on detection of IR radiation emitted by the tissue as a result of its temperature. Modern IR detectors sense thermal emissions and produce a heat map of surface temperature distribution in tissues. Thus, the IR spectrum offers a variety of imaging applications particularly useful in clinical diagnostic area, ranging from high-resolution, depth-resolved visualization of tissue to temperature variation assessment. These techniques have been helpful in the diagnosis of many medical conditions including skin/breast cancer, arthritis, allergy, burns, and others. In this review, we discuss current roles of IR-imaging techniques for diagnostic applications in dermatology with an emphasis on skin cancer, allergies, blisters, burns and wounds.

Noncontact localized internal infrared radiation measurement using an infrared point detector

NASA Astrophysics Data System (ADS)

Hisaka, Masaki

2018-06-01

The techniques for temperature measurement within the human body are important for clinical applications. A method for noncontact local infrared (IR) radiation measurements was investigated deep within an object to simulate how the core human body temperature can be obtained. To isolate the IR light emitted from a specific area within the object from the external noise, the radiating IR light was detected using an IR point detector, which comprises a pinhole and a thermopile positioned at an imaging relation with the region of interest within the object. The structure of the helical filament radiating IR light inside a light bulb was thermally imaged by scanning the bulb in two dimensions. Moreover, this approach was used to effectively measure IR light in the range of human body temperature using a glass plate placed in front of the heat source, mimicking the ocular fundus.

Limitations of insulin resistance assessment in polycystic ovary syndrome

PubMed Central

Lewandowski, Krzysztof C; Płusajska, Justyna; Horzelski, Wojciech; Bieniek, Ewa; Lewiński, Andrzej

2018-01-01

Background Though insulin resistance (IR) is common in polycystic ovary syndrome (PCOS), there is no agreement as to what surrogate method of assessment of IR is most reliable. Subjects and methods In 478 women with PCOS, we compared methods based on fasting insulin and either fasting glucose (HOMA-IR and QUICKI) or triglycerides (McAuley Index) with IR indices derived from glucose and insulin during OGTT (Belfiore, Matsuda and Stumvoll indices). Results There was a strong correlation between IR indices derived from fasting values HOMA-IR/QUICKI, r = −0.999, HOMA-IR/McAuley index, r = −0.849 and between all OGTT-derived IR indices (e.g. r = −0.876, for IRI/Matsuda, r = −0.808, for IRI/Stumvoll, and r = 0.947, for Matsuda/Stumvoll index, P < 0.001 for all), contrasting with a significant (P < 0.001), but highly variable correlation between IR indices derived from fasting vs OGTT-derived variables, ranging from r = −0.881 (HOMA-IR/Matsuda), through r = 0.58, or r = −0.58 (IRI/HOMA-IR, IRI/QUICKI, respectively) to r = 0.41 (QUICKI/Stumvoll), and r = 0.386 for QUICKI/Matsuda indices. Detailed comparison between HOMA-IR and IRI revealed that concordance between HOMA and IRI was poor for HOMA-IR/IRI values above 75th and 90th percentile. For instance, only 53% (70/132) women with HOMA-IR >75th percentile had IRI value also above 75th percentile. There was a significant, but weak correlation of all IR indices with testosterone concentrations. Conclusions Significant number of women with PCOS can be classified as being either insulin sensitive or insulin resistant depending on the method applied, as correlation between various IR indices is highly variable. Clinical application of surrogate indices for assessment of IR in PCOS must be therefore viewed with an extreme caution. PMID:29436386

A Satellite Infrared Technique for Diurnal Rainfall Variability Studies

NASA Technical Reports Server (NTRS)

Anagnostou, Emmanouil

1998-01-01

Reliable information on the distribution of precipitation at high temporal resolution (

Influence of iridium doping in MgB2 superconducting wires

NASA Astrophysics Data System (ADS)

Grivel, J.-C.

2018-04-01

MgB2 wires with iridium doping were manufactured using the in-situ technique in a composite Cu-Nb sheath. Reaction was performed at 700 °C, 800 °C or 900 °C for 1 h in argon atmosphere. A maximum of about 1.5 at.% Ir replaces Mg in MgB2. The superconducting transition temperature is slightly lowered by Ir doping. The formation of IrMg3 and IrMg4 secondary phase particles is evidenced, especially for a nominal stoichiometry with 2.0 at.% Ir doping. The critical current density and accommodation field of the wires are strongly dependent on the Ir content and are generally weakened in the presence of Ir, although the effect is less pronounced at lower temperatures.

Metal-insulator transition and superconductivity in the spinel-type Cu(Ir1-xRhx)2S4 system

NASA Astrophysics Data System (ADS)

Matsumoto, Nobuhiro; Endoh, Ryo; Nagata, Shoichi; Furubayashi, Takao; Matsumoto, Takehiko

1999-08-01

The normal thiospinel CuIr2S4 exhibits a temperature-induced metal-insulator (M-I) transition around 226 K with structural transformation, showing hysteresis on heating and cooling. It has been verified that d electrons of Ir atom on the octahedral B sites have a significant role for the M-I transition. On the other hand, CuRh2S4 is a superconductor with the transition temperature Tc=4.70 K, which is well understood on the basis of the BCS theory. It is important to investigate the effect on the M-I transition by substitution of Rh for Ir. We have systematically studied structural transformation and electrical and magnetic properties of Cu(Ir1-xRhx)2S4. The features of the M-I transition change with Rh concentration x. A phase diagram of temperature versus x will be proposed for the Cu(Ir1-xRhx)2S4 system. The sharp M-I transition temperature varies drastically from 226 to 93 K with x from 0.00 to 0.17 and disappears around x=0.20. In a region of 0.00<=x<=0.20, the magnetic susceptibility begins decreasing at a constant onset temperature 226 K on cooling process and shows rather broad temperature variation, even though the metallic state is kept in the resistivity. The sharp M-I transition can take place after the suppression of magnitude in the susceptibility has sufficiently developed far below 226 K. These experimental results are discussed with emphasis on the intrinsic difference between Cu(Ir1-xRhx)2S4 and CuIr2(S1-xSex)4 systems. Furthermore, we will mention the superconductivity for both systems of Cu(Ir1-xRhx)2S4 with high-Rh concentration region and Cu1-xNixRh2S4.

Realization of Ru-C Eutectic Point for Evaluation of W-Re and IrRh/Ir Thermocouples

NASA Astrophysics Data System (ADS)

Ogura, H.; Masuyama, S.; Izuchi, M.; Yamazawa, K.; Arai, M.

2015-03-01

Tungsten-rhenium (W-Re) thermocouples are widely used in industry for measurements at high temperatures, up to . Since the electromotive force (emf) of a W-Re thermocouple is known to change during exposure at high temperatures, evaluation of the emf stability is essential for measuring temperature precisely and for realizing precise temperature control used to ensure the quality of products subject to annealing processes. To evaluate precisely the thermoelectric stability around , two Ru-C cells (crucible and Ru-C eutectic alloy) were constructed in our laboratory. The key feature of the cells is that their dimensions are large to ensure there is sufficient immersion available to evaluate the homogeneity characteristics of the thermocouples. By using one of the Ru-C cells, the drift and inhomogeneity of Type C (tungsten-5 % rhenium vs tungsten-26 % rhenium) thermocouples during an exposure to high temperature around were evaluated. Furthermore, to explore possible applications of the eutectic point to other types of high-temperature thermocouples, the drift of an IrRh/Ir thermocouple (iridium-40 % rhodium vs iridium) was also evaluated using another Ru-C cell. The tests with W-Re and IrRh/Ir thermocouples demonstrate that the newly developed Ru-C cells can be used to successfully realize melting plateaux repeatedly. This enables the long-term drift measurements essential for the evaluation and improvement of high-temperature thermocouples. The results obtained in this study will also be useful for evaluating the uncertainty of thermocouple calibrations at around.

Brown adipose tissue thermogenesis does not explain the intra-administration hyperthermic sign-reversal induced by serial administrations of 60% nitrous oxide to rats.

PubMed

Al-Noori, Salwa; Ramsay, Douglas S; Cimpan, Andreas; Maltzer, Zoe; Zou, Jessie; Kaiyala, Karl J

2016-08-01

Initial administration of ≥60% nitrous oxide (N2O) to rats promotes hypothermia primarily by increasing whole-body heat loss. We hypothesized that the drug promotes heat loss via the tail and might initially inhibit thermogenesis via brown adipose tissue (BAT), major organs of thermoregulation in rodents. Following repeated administrations, N2O inhalation evokes hyperthermia underlain by increased whole-body heat production. We hypothesized that elevated BAT thermogenesis plays a role in this thermoregulatory sign reversal. Using dual probe telemetric temperature implants and infrared (IR) thermography, we assessed the effects of nine repeated 60% N2O administrations compared to control (con) administrations on core temperature, BAT temperature, lumbar back temperature and tail temperature. Telemetric core temperature, telemetric BAT temperature, and IR BAT temperature were reduced significantly during initial 60% N2O inhalation (p≤0.001 compared to con). IR thermography revealed that acute N2O administration unexpectedly reduced tail temperature (p=0.0001) and also inhibited IR lumbar temperature (p<0.0001). In the 9th session, N2O inhalation significantly increased telemetric core temperature (p=0.007) indicative of a hyperthermic sign reversal, yet compared to control administrations, telemetric BAT temperature (p=0.86), IR BAT temperature (p=0.85) and tail temperature (p=0.47) did not differ significantly. Thus, an initial administration of 60% N2O at 21°C may promote hypothermia via reduced BAT thermogenesis accompanied by tail vasoconstriction as a compensatory mechanism to limit body heat loss. Following repeated N2O administrations rats exhibit a hyperthermic core temperature but a normalized BAT temperature, suggesting induction of a hyperthermia-promoting thermogenic adaptation of unknown origin. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analysis of The Surface Radiative Budget Using ATLAS Data for San Juan, Puerto Rico

NASA Technical Reports Server (NTRS)

Luvall, Jeffrey C.; Rickman, D. L.; Gonzalez, J.; Comarazamy, Daniel; Picon, Ana

2007-01-01

The additional beating of the air over the city is the result of the replacement of naturally vegetated surfaces with those composed of asphalt, concrete, rooftops and other man-made materials. The temperatures of these artificial surfaces can be 20 to 40 C higher than vegetated surfaces. This produces a dome of elevated air temperatures 5 to 8 C greater over the city, compared to the air temperatures over adjacent rural areas. Urban landscapes are a complex mixture of vegetated and nonvegetated surfaces. It is difficult to take enough temperature measurements over a large city area to characterize the complexity of urban radiant surface temperature variability. The NASA Airborne Thermal and Land Applications Sensor (ATLAS) operates in the visual and IR bands was used in February 2004 to collect data from San Juan, Puerto Rico with the main objective of investigating the Urban Heat Island (UHI) in tropical cities.

Mock Target Window OTR and IR Design and Testing

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

Wass, Alexander Joseph

In order to fully verify temperature measurements made on the target window using infrared (IR) optical non-contact methods, actual comparative measurements are made with a real beam distribution as the heat source using Argonne National Laboratory’s (ANL) 35 MeV electron accelerator. Using Monte Carlo N-Particle (MCNP) simulations and thermal Finite Element Analysis (FEA), a cooled mock target window with thermocouple implants is designed to be used in such a test to achieve window temperatures up to 700°C. An uncoated and blackcoated mock window is designed to enhance the IR temperature measurements and verify optical transmitted radiation (OTR) imagery. This allowsmore » us to fully verify and characterize our temperature accuracy with our current IR camera method and any future method we may wish to explore using actual production conditions. This test also provides us with valuable conclusions/concerns regarding the calibration method we developed using our IR test stand at TA-53 in MPF-14.« less

Measuring and Estimating Normalized Contrast in Infrared Flash Thermography

NASA Technical Reports Server (NTRS)

Koshti, Ajay M.

2013-01-01

Infrared flash thermography (IRFT) is used to detect void-like flaws in a test object. The IRFT technique involves heating up the part surface using a flash of flash lamps. The post-flash evolution of the part surface temperature is sensed by an IR camera in terms of pixel intensity of image pixels. The IR technique involves recording of the IR video image data and analysis of the data using the normalized pixel intensity and temperature contrast analysis method for characterization of void-like flaws for depth and width. This work introduces a new definition of the normalized IR pixel intensity contrast and normalized surface temperature contrast. A procedure is provided to compute the pixel intensity contrast from the camera pixel intensity evolution data. The pixel intensity contrast and the corresponding surface temperature contrast differ but are related. This work provides a method to estimate the temperature evolution and the normalized temperature contrast from the measured pixel intensity evolution data and some additional measurements during data acquisition.

Synthesis of monoclinic IrTe 2 under high pressure and its physical properties

DOE PAGES

Li, X.; Yan, J. -Q.; Singh, D. J.; ...

2015-10-12

In a pressure-temperature (P-T) diagram for synthesizing IrTe 2 compounds, the well-studied trigonal (H) phase with the CdI 2-type structure is stable at low pressures. The superconducting cubic (C) phase can be synthesized under higher temperatures and pressures. A rhombohedral phase with the crystal structure similar to the C phase can be made at ambient pressure; but the phase contains a high concentration of Ir deficiency. Here, we report that a rarely studied monoclinic (M) phase can be stabilized in narrow ranges of pressure and temperature in this P-T diagram. Moreover, the peculiar crystal structure of the M-IrTe 2 eliminatesmore » the tendency to form Ir-Ir dimers found in the H phase. The M phase has been fully characterized by structural determination and measurements of electrical resistivity, thermoelectric power, DC magnetization, and specific heat. These physical properties have been compared with those in the H and C phases of Ir 1-xTe 2. Finally, we present magnetic and transport properties and specific heat of the M-IrTe 2 can be fully justified by calculations with the density-functional theory.« less

Infrared imaging: a potential powerful tool for neuroimaging and neurodiagnostics

PubMed Central

Khoshakhlagh, Arezou; Gunapala, Sarath D.

2017-01-01

Abstract. Infrared (IR) imaging is used to detect the subtle changes in temperature needed to accurately detect and monitor disease. Technological advances have made IR a highly sensitive and reliable detection tool with strong potential in medical and neurophotonics applications. An overview of IR imaging specifically investigating quantum well IR detectors developed at Jet Propulsion Laboratory for a noninvasive, nonradiating imaging tool is provided, which could be applied for neuroscience and neurosurgery where it involves sensitive cellular temperature change. PMID:28382311

Theoretical framework for quantitatively estimating ultrasound beam intensities using infrared thermography.

PubMed

Myers, Matthew R; Giridhar, Dushyanth

2011-06-01

In the characterization of high-intensity focused ultrasound (HIFU) systems, it is desirable to know the intensity field within a tissue phantom. Infrared (IR) thermography is a potentially useful method for inferring this intensity field from the heating pattern within the phantom. However, IR measurements require an air layer between the phantom and the camera, making inferences about the thermal field in the absence of the air complicated. For example, convection currents can arise in the air layer and distort the measurements relative to the phantom-only situation. Quantitative predictions of intensity fields based upon IR temperature data are also complicated by axial and radial diffusion of heat. In this paper, mathematical expressions are derived for use with IR temperature data acquired at times long enough that noise is a relatively small fraction of the temperature trace, but small enough that convection currents have not yet developed. The relations were applied to simulated IR data sets derived from computed pressure and temperature fields. The simulation was performed in a finite-element geometry involving a HIFU transducer sonicating upward in a phantom toward an air interface, with an IR camera mounted atop an air layer, looking down at the heated interface. It was found that, when compared to the intensity field determined directly from acoustic propagation simulations, intensity profiles could be obtained from the simulated IR temperature data with an accuracy of better than 10%, at pre-focal, focal, and post-focal locations. © 2011 Acoustical Society of America

Simultaneous Multiwavelength Variability Characterization of the Free-floating Planetary-mass Object PSO J318.5‑22

NASA Astrophysics Data System (ADS)

Biller, Beth A.; Vos, Johanna; Buenzli, Esther; Allers, Katelyn; Bonnefoy, Mickaël; Charnay, Benjamin; Bézard, Bruno; Allard, France; Homeier, Derek; Bonavita, Mariangela; Brandner, Wolfgang; Crossfield, Ian; Dupuy, Trent; Henning, Thomas; Kopytova, Taisiya; Liu, Michael C.; Manjavacas, Elena; Schlieder, Joshua

2018-02-01

We present simultaneous Hubble Space Telescope (HST) WFC3+Spitzer IRAC variability monitoring for the highly variable young (∼20 Myr) planetary-mass object PSO J318.5‑22. Our simultaneous HST + Spitzer observations covered approximately two rotation periods with Spitzer and most of a rotation period with the HST. We derive a period of 8.6 ± 0.1 hr from the Spitzer light curve. Combining this period with the measured v\\sin i for this object, we find an inclination of 56.°2 ± 8.°1. We measure peak-to-trough variability amplitudes of 3.4% ± 0.1% for Spitzer Channel 2 and 4.4%–5.8% (typical 68% confidence errors of ∼0.3%) in the near-IR bands (1.07–1.67 μm) covered by the WFC3 G141 prism—the mid-IR variability amplitude for PSO J318.5‑22 is one of the highest variability amplitudes measured in the mid-IR for any brown dwarf or planetary-mass object. Additionally, we detect phase offsets ranging from 200° to 210° (typical error of ∼4°) between synthesized near-IR light curves and the Spitzer mid-IR light curve, likely indicating depth-dependent longitudinal atmospheric structure in this atmosphere. The detection of similar variability amplitudes in wide spectral bands relative to absorption features suggests that the driver of the variability may be inhomogeneous clouds (perhaps a patchy haze layer over thick clouds), as opposed to hot spots or compositional inhomogeneities at the top-of-atmosphere level.

Automated processing of thermal infrared images of Osservatorio Vesuviano permanent surveillance network by using Matlab code

NASA Astrophysics Data System (ADS)

Sansivero, Fabio; Vilardo, Giuseppe; Caputo, Teresa

2017-04-01

The permanent thermal infrared surveillance network of Osservatorio Vesuviano (INGV) is composed of 6 stations which acquire IR frames of fumarole fields in the Campi Flegrei caldera and inside the Vesuvius crater (Italy). The IR frames are uploaded to a dedicated server in the Surveillance Center of Osservatorio Vesuviano in order to process the infrared data and to excerpt all the information contained. In a first phase the infrared data are processed by an automated system (A.S.I.R.A. Acq- Automated System of IR Analysis and Acquisition) developed in Matlab environment and with a user-friendly graphic user interface (GUI). ASIRA daily generates time-series of residual temperature values of the maximum temperatures observed in the IR scenes after the removal of seasonal effects. These time-series are displayed in the Surveillance Room of Osservatorio Vesuviano and provide information about the evolution of shallow temperatures field of the observed areas. In particular the features of ASIRA Acq include: a) efficient quality selection of IR scenes, b) IR images co-registration in respect of a reference frame, c) seasonal correction by using a background-removal methodology, a) filing of IR matrices and of the processed data in shared archives accessible to interrogation. The daily archived records can be also processed by ASIRA Plot (Matlab code with GUI) to visualize IR data time-series and to help in evaluating inputs parameters for further data processing and analysis. Additional processing features are accomplished in a second phase by ASIRA Tools which is Matlab code with GUI developed to extract further information from the dataset in automated way. The main functions of ASIRA Tools are: a) the analysis of temperature variations of each pixel of the IR frame in a given time interval, b) the removal of seasonal effects from temperature of every pixel in the IR frames by using an analytic approach (removal of sinusoidal long term seasonal component by using a polynomial fit Matlab function - LTFC_SCOREF), c) the export of data in different raster formats (i.e. Surfer grd). An interesting example of elaborations of the data produced by ASIRA Tools is the map of the temperature changing rate, which provide remarkable information about the potential migration of fumarole activity. The high efficiency of Matlab in processing matrix data from IR scenes and the flexibility of this code-developing tool proved to be very useful to produce applications to use in volcanic surveillance aimed to monitor the evolution of surface temperatures field in diffuse degassing volcanic areas.

Optical photometric variable stars towards the Galactic H II region NGC 2282

NASA Astrophysics Data System (ADS)

Dutta, Somnath; Mondal, Soumen; Joshi, Santosh; Jose, Jessy; Das, Ramkrishna; Ghosh, Supriyo

2018-05-01

We report here CCD I-band time series photometry of a young (2-5 Myr) cluster NGC 2282, in order to identify and understand the variability of pre-main-sequence (PMS) stars. The I-band photometry, down to ˜20.5 mag, enables us to probe the variability towards the lower mass end (˜0.1 M⊙) of PMS stars. From the light curves of 1627 stars, we identified 62 new photometric variable candidates. Their association with the region was established from H α emission and infrared (IR) excess. Among 62 variables, 30 young variables exhibit H α emission, near-IR (NIR)/mid-IR (MIR) excess or both and are candidate members of the cluster. Out of 62 variables, 41 are periodic variables, with a rotation rate ranging from 0.2-7 d. The period distribution exhibits a median period at ˜1 d, as in many young clusters (e.g. NGC 2264, ONC, etc.), but it follows a unimodal distribution, unlike others that have bimodality, with slow rotators peaking at ˜6-8 d. To investigate the rotation-disc and variability-disc connection, we derived the NIR excess from Δ(I - K) and the MIR excess from Spitzer [3.6]-[4.5] μm data. No conclusive evidence of slow rotation with the presence of discs around stars and fast rotation for discless stars is obtained from our periodic variables. A clear increasing trend of the variability amplitude with IR excess is found for all variables.

Effects of thermo-mechanical behavior and hinge geometry on folding response of shape memory polymer sheets

NASA Astrophysics Data System (ADS)

Mailen, Russell W.; Dickey, Michael D.; Genzer, Jan; Zikry, Mohammed

2017-11-01

Shape memory polymer (SMP) sheets patterned with black ink hinges change shape in response to external stimuli, such as absorbed thermal energy from an infrared (IR) light. The geometry of these hinges, including size, orientation, and location, and the applied thermal loads significantly influence the final folded shape of the sheet, but these variables have not been fully investigated. We perform a systematic study on SMP sheets to fundamentally understand the effects of single and double hinge geometries, hinge orientation and spacing, initial temperature, heat flux intensity, and pattern width on the folding behavior. We have developed thermo-viscoelastic finite element models to characterize and quantify the stresses, strains, and temperatures as they relate to SMP shape changes. Our predictions indicate that hinge orientation can be used to reduce the total bending angle, which is the angle traversed by the folding face of the sheet. Two parallel hinges increase the total bending angle, and heat conduction between the hinges affects the transient folding response. IR intensity and initial temperatures can also influence the transient folding behavior. These results can provide guidelines to optimize the transient folding response and the three-dimensional folded structure obtained from self-folding polymer origami sheets that can be applied for myriad applications.

Effect of IrMn inserted layer on anomalous-Hall resistance and spin-Hall magnetoresistance in Pt/IrMn/YIG heterostructures

NASA Astrophysics Data System (ADS)

Shang, T.; Yang, H. L.; Zhan, Q. F.; Zuo, Z. H.; Xie, Y. L.; Liu, L. P.; Zhang, S. L.; Zhang, Y.; Li, H. H.; Wang, B. M.; Wu, Y. H.; Zhang, S.; Li, Run-Wei

2016-10-01

We report an investigation of anomalous-Hall resistance (AHR) and spin-Hall magnetoresistance (SMR) in Pt/Ir20Mn80/Y3Fe5O12 (Pt/IrMn/YIG) heterostructures. The AHR of Pt/IrMn/YIG heterostructures with an antiferromagnetic inserted layer is dramatically enhanced as compared to that of the Pt/YIG bilayer. The temperature dependent AHR behavior is nontrivial, while the IrMn thickness dependent AHR displays a peak at an IrMn thickness of 3 nm. The observed SMR in the temperature range of 10-300 K indicates that the spin current generated in the Pt layer can penetrate the IrMn layer (≤3 nm) to interact with the ferromagnetic YIG layer. The lack of conventional anisotropic magnetoresistance (AMR) implies that the insertion of the IrMn layer between Pt and YIG could efficiently suppress the magnetic proximity effect (MPE) on induced Pt moments by YIG.

First quadruple-glycine bridging mono-lanthanide-substituted borotungstate hybrids.

PubMed

Liu, Jiancai; Yu, Jing; Han, Qing; Wen, Yue; Chen, Lijuan; Zhao, Junwei

2016-10-18

A class of novel organic-inorganic hybrid lanthanide (Ln)-substituted Keggin-type borotungstates K 4 Na 4 H 4 [Ln 2 (gly) 4 (α-BW 11 O 39 ) 2 ]·23H 2 O [Ln = Ce 3+ (1), Pr 3+ (2), Nd 3+ (3), Sm 3+ (4), Eu 3+ (5), Tm 3+ (6); gly = glycine] have been synthesized from the reaction of K 8 [BW 11 O 39 H]·13H 2 O, NaAc·6H 2 O and Ln(NO 3 ) 3 ·6H 2 O by employing gly ligands as structure-stabilizing agents in the conventional aqueous solution system and structurally characterized by elemental analyses, IR spectroscopy, thermogravimetric (TG) analyses, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. The common prominent structural feature of isomorphic 1-6 is that all of them consist of two mono-Ln-substituted Keggin [Ln(α-BW 11 O 39 )] 6- fragments linked by four gly ligands, furnishing an intriguing dimeric assembly of the quadruple-gly-connective mono-Ln-substituted borotungstate, in which each carboxylic oxygen atom from gly ligands is bound to Ln 3+ cations in the μ 2 -O or μ 3 -O mode. To the best of our knowledge, 1-6 represent the first examples of inorganic-organic hybrid Ln-substituted borotungstates functionalized by quadruple amino acid bridges. The solid-state photoluminescence properties of 3-5 have been determined at ambient temperature and the photoluminescence emission spectra exhibit the characteristic emission bands derived from Ln 3+ centers. The thermostability of 1-6 has been studied and the thermal decomposition procedure of 3 has been comprehensively investigated with the assistance of variable-temperature PXRD patterns and variable-temperature IR spectra. Furthermore, magnetic susceptibility measurements of 1, 2 and 4 have been conducted.

Global inter-comparison of microwave and infrared LST from multiple sensors (AMSR-E, MODIS, SEVIRI, GOES, and MTSAT-2)

NASA Astrophysics Data System (ADS)

Ermida, Sofia L.; Jiménez, Carlos; Prigent, Catherine; Trigo, Isabel F.; DaCamara, Carlos C.

2017-04-01

Land Surface Temperature (LST) is an important diagnostic parameter of land surface conditions. Satellite LST products generally rely on measurements in the thermal infrared (IR) atmospheric window, which only allows clear sky estimates. Microwave (MW) observations can alternatively be used to derive an all-weather LST. Here we present an inter-comparison between LST derived from the Advanced Microwave Scanning Radiometer - Earth observation system (AMSR-E), the MODerate resolution Imaging Spectroradiometer (MODIS) on-board Aqua, the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on-board Meteosat Second Generation (MSG) satellites, the Geostationary Operational Environmental Satellite (GOES) and the Japanese Meteorological Imager (JAMI) on-board the Multifunction Transport SATellite (MTSAT-2). The higher discrepancies between MW and IR products are observed over snow covered areas. MW emissivity is highly variable for snow-covered ground and not always properly accounted for by the climatological emissivity used in the retrieval. There is a conspicuous bias between MODIS and AMSR-E over desert areas, which is most likely related to the underestimation of LST by MODIS as previously reported in other studies. Inter-comparison between all IR and MW retrievals shows that the STD of the differences between MW and IR LST is generally higher than between IR retrievals. However, the biases between MW and IR LST are, in some cases, of the same order as the ones observed among infrared products. In particular, GOES presents a daytime bias with respect to AMSR-E of 0.45 K whereas the bias with respect to MODIS is 0.60 K. Given that AMSR-E can provide LST under cloudy conditions, the use of microwaves, considering simultaneous overpasses with IR, represents an increase of more than 250% of the number of available LST estimates over equatorial regions. With the MW products of a comparable quality to the IR ones, the MW LST is a very powerful complement of the IR estimates.

Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber.

PubMed

Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

2015-05-11

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of -0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber.

Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber

PubMed Central

Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

2015-01-01

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of −0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber. PMID:25970257

Infrared Thermography Flight Experimentation

NASA Technical Reports Server (NTRS)

Blanchard, Robert C.; Carter, Matthew L.; Kirsch, Michael

2003-01-01

Analysis was done on IR data collected by DFRC on May 8, 2002. This includes the generation of a movie to initially examine the IR flight data. The production of the movie was challenged by the volume of data that needed to be processed, namely 40,500 images with each image (256 x 252) containing over 264 million points (pixel depth 4096). It was also observed during the initial analysis that the RTD surface coating has a different emissivity than the surroundings. This fact added unexpected complexity in obtaining a correlation between RTD data and IR data. A scheme was devised to generate IR data near the RTD location which is not affected by the surface coating This scheme is valid as long as the surface temperature as measured does not change too much over a few pixel distances from the RTD location. After obtaining IR data near the RTD location, it is possible to make a direct comparison with the temperature as measured during the flight after adjusting for the camera s auto scaling. The IR data seems to correlate well to the flight temperature data at three of the four RID locations. The maximum count intensity occurs closely to the maximum temperature as measured during flight. At one location (RTD #3), there is poor correlation and this must be investigated before any further progress is possible. However, with successful comparisons at three locations, it seems there is great potential to be able to find a calibration curve for the data. Moreover, as such it will be possible to measure temperature directly from the IR data in the near future.

Tungsten and iridium multilayered structure by DGP as ablation-resistance coatings for graphite

NASA Astrophysics Data System (ADS)

Wu, Wangping; Chen, Zhaofeng; Cheng, Han; Wang, Liangbing; Zhang, Ying

2011-06-01

Oxidation protection of carbon material under ultra-high temperature is a serious problem. In this paper, a newly designed multilayer coating of W/Ir was produced onto the graphite substrate by double glow plasma. As comparison, the Ir single-layer coating on the graphite was also prepared. The ablation property and thermal stability of the coatings were studied at 2000 °C in an oxyacetylene torch flame. Ablation tests showed that the coated graphite substrates were protected more effectively by W/Ir multilayer coating than Ir single-layer coating. Ir single-layer coating after ablation kept the integrality, although there was a poor adhesion of the Ir coating to the graphite substrate because of the thermal expansion mismatch and the non-wetting of the carbon by Ir coating. The mass loss rate of the W/Ir-coated specimen after ablation was about 1.62%. The interface of W/Ir multilayer coating and the graphite substrate exhibited good adherence no evidence of delamination after ablation. W/Ir multilayer coating could be useful for protecting graphite in high-temperature application for a short time.

VO2 /TiN Plasmonic Thermochromic Smart Coatings for Room-Temperature Applications.

PubMed

Hao, Qi; Li, Wan; Xu, Huiyan; Wang, Jiawei; Yin, Yin; Wang, Huaiyu; Ma, Libo; Ma, Fei; Jiang, Xuchuan; Schmidt, Oliver G; Chu, Paul K

2018-03-01

Vanadium dioxide/titanium nitride (VO 2 /TiN) smart coatings are prepared by hybridizing thermochromic VO 2 with plasmonic TiN nanoparticles. The VO 2 /TiN coatings can control infrared (IR) radiation dynamically in accordance with the ambient temperature and illumination intensity. It blocks IR light under strong illumination at 28 °C but is IR transparent under weak irradiation conditions or at a low temperature of 20 °C. The VO 2 /TiN coatings exhibit a good integral visible transmittance of up to 51% and excellent IR switching efficiency of 48% at 2000 nm. These unique advantages make VO 2 /TiN promising as smart energy-saving windows. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lighthouse in the dust: infrared echoes of periodic emission from massive black hole binaries★

NASA Astrophysics Data System (ADS)

D'Orazio, Daniel J.; Haiman, Zoltán

2017-09-01

The optical and UV emission from sub-parsec massive black hole binaries (MBHBs) in active galactic nuclei (AGNs) is believed to vary periodically, on time-scales comparable to the binary's orbital time. If driven by accretion rate fluctuations, the variability could be isotropic. If dominated by relativistic Doppler modulation, the variability should instead be anisotropic, resembling a rotating forward-beamed lighthouse. We consider the infrared (IR) reverberation of either type of periodic emission by pc-scale circumbinary dust tori. We predict the phase and amplitude of IR variability as a function of the ratio of dust light crossing time to the source variability period, and of the torus inclination and opening angle. We enumerate several differences between the isotropic and anisotropic cases. Interestingly, for a nearly face-on binary with an inclined dust torus, the Doppler boost can produce IR variability without any observable optical/UV variability. Such orphan-IR variability would have been missed in optical searches for periodic AGNs. We apply our models to time-domain WISE IR data from the MBHB candidate PG 1302-102 and find consistency with dust reverberation by both isotropically emitting and Doppler-boosted sources in the shorter wavelength W1-W2 (2.8 → 5.3 μm) bands. We constrain the dust torus to be thin (aspect ratio ˜ 0.1), with an inner radius at 1-5 pc. More generally, our dust-echo models will aid in identifying new MBHB candidates, determining their nature and constraining the physical properties of MBHBs and their dust tori.

Observational Evidence Linking Interstellar UV Absorption to PAH Molecules

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

Blasberger, Avi; Behar, Ehud; Perets, Hagai B.

The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μ m IR emission bands, which are specified by their modes of vibration. A definitive empirical link between the 2175 Å UV extinction and the IR PAH emission bands, however, is still missing. We present a new sample of hot stars that have both 2175 Å absorptionmore » and IR PAH emission. We find significant shifts of the central wavelength of the UV absorption feature, up to 2350 Å, but predominantly in stars that also have IR PAH emission. These UV shifts depend on stellar temperature in a fashion that is similar to the shifts of the 6.2 and 7.7 μ m IR PAH bands, that is, the features are increasingly more redshifted as the stellar temperature decreases, but only below ∼15 kK. Above 15 kK both UV and IR features retain their nominal values. Moreover, we find a suggestive correlation between the UV and IR shifts. We hypothesize that these similar dependences of both the UV and IR features on stellar temperature hint at a common origin of the two in PAH molecules and may establish the missing link between the UV and IR observations. We further suggest that the shifts depend on molecular size, and that the critical temperature of ∼15 kK above which no shifts are observed is related to the onset of UV-driven hot-star winds and their associated shocks.« less

Observational Evidence Linking Interstellar UV Absorption to PAH Molecules

NASA Astrophysics Data System (ADS)

Blasberger, Avi; Behar, Ehud; Perets, Hagai B.; Brosch, Noah; Tielens, Alexander G. G. M.

2017-02-01

The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μm IR emission bands, which are specified by their modes of vibration. A definitive empirical link between the 2175 Å UV extinction and the IR PAH emission bands, however, is still missing. We present a new sample of hot stars that have both 2175 Å absorption and IR PAH emission. We find significant shifts of the central wavelength of the UV absorption feature, up to 2350 Å, but predominantly in stars that also have IR PAH emission. These UV shifts depend on stellar temperature in a fashion that is similar to the shifts of the 6.2 and 7.7 μm IR PAH bands, that is, the features are increasingly more redshifted as the stellar temperature decreases, but only below ˜15 kK. Above 15 kK both UV and IR features retain their nominal values. Moreover, we find a suggestive correlation between the UV and IR shifts. We hypothesize that these similar dependences of both the UV and IR features on stellar temperature hint at a common origin of the two in PAH molecules and may establish the missing link between the UV and IR observations. We further suggest that the shifts depend on molecular size, and that the critical temperature of ˜15 kK above which no shifts are observed is related to the onset of UV-driven hot-star winds and their associated shocks.

Morin transition temperature in (0001)-oriented α-Fe{sub 2}O{sub 3} thin film and effect of Ir doping

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

Shimomura, Naoki, E-mail: shimomura@ecei.tohoku.ac.jp; Pati, Satya Prakash; Sato, Yuji

2015-05-07

The structural properties and Morin transition in c-plane-oriented α-Fe{sub 2}O{sub 3} and Ir-doped α-Fe{sub 2}O{sub 3} thin films have been investigated. The enhancement of the Morin transition temperature (T{sub M}) in α-Fe{sub 2}O{sub 3} film by Ir doping has been demonstrated. The T{sub M} in the c-plane-oriented α-Fe{sub 2}O{sub 3} thin film was determined from the temperature-dependent in-plane magnetization and change of coercivity (H{sub c}); this T{sub M} value was found close to that of bulk α-Fe{sub 2}O{sub 3}. The spin directions of non-doped and Ir-doped α-Fe{sub 2}O{sub 3} at room temperature were also estimated from conversion electron Mössbauer spectroscopymore » measurements. We confirmed that Ir doping dramatically enhances the T{sub M} of α-Fe{sub 2}O{sub 3} thin film.« less

Data indicating temperature response of Ti-6Al-4V thin-walled structure during its additive manufacture via Laser Engineered Net Shaping.

PubMed

Marshall, Garrett J; Thompson, Scott M; Shamsaei, Nima

2016-06-01

An OPTOMEC Laser Engineered Net Shaping (LENS(™)) 750 system was retrofitted with a melt pool pyrometer and in-chamber infrared (IR) camera for nondestructive thermal inspection of the blown-powder, direct laser deposition (DLD) process. Data indicative of temperature and heat transfer within the melt pool and heat affected zone atop a thin-walled structure of Ti-6Al-4V during its additive manufacture are provided. Melt pool temperature data were collected via the dual-wavelength pyrometer while the dynamic, bulk part temperature distribution was collected using the IR camera. Such data are provided in Comma Separated Values (CSV) file format, containing a 752×480 matrix and a 320×240 matrix of temperatures corresponding to individual pixels of the pyrometer and IR camera, respectively. The IR camera and pyrometer temperature data are provided in blackbody-calibrated, raw forms. Provided thermal data can aid in generating and refining process-property-performance relationships between laser manufacturing and its fabricated materials.

Data indicating temperature response of Ti–6Al–4V thin-walled structure during its additive manufacture via Laser Engineered Net Shaping

PubMed Central

Marshall, Garrett J.; Thompson, Scott M.; Shamsaei, Nima

2016-01-01

An OPTOMEC Laser Engineered Net Shaping (LENS™) 750 system was retrofitted with a melt pool pyrometer and in-chamber infrared (IR) camera for nondestructive thermal inspection of the blown-powder, direct laser deposition (DLD) process. Data indicative of temperature and heat transfer within the melt pool and heat affected zone atop a thin-walled structure of Ti–6Al–4V during its additive manufacture are provided. Melt pool temperature data were collected via the dual-wavelength pyrometer while the dynamic, bulk part temperature distribution was collected using the IR camera. Such data are provided in Comma Separated Values (CSV) file format, containing a 752×480 matrix and a 320×240 matrix of temperatures corresponding to individual pixels of the pyrometer and IR camera, respectively. The IR camera and pyrometer temperature data are provided in blackbody-calibrated, raw forms. Provided thermal data can aid in generating and refining process-property-performance relationships between laser manufacturing and its fabricated materials. PMID:27054180

In situ observation of carbon nanotube layer growth on microbolometers with substrates at ambient temperature

NASA Astrophysics Data System (ADS)

Svatoš, Vojtěch; Gablech, Imrich; Ilic, B. Robert; Pekárek, Jan; Neužil, Pavel

2018-03-01

Carbon nanotubes (CNTs) have near unity infrared (IR) absorption efficiency, making them extremely attractive for IR imaging devices. Since CNT growth occurs at elevated temperatures, the integration of CNTs with IR imaging devices is challenging and has not yet been achieved. Here, we show a strategy for implementing CNTs as IR absorbers using differential heating of thermally isolated microbolometer membranes in a C2H2 environment. During the process, CNTs were catalytically grown on the surface of a locally heated membrane, while the substrate was maintained at an ambient temperature. CNT growth was monitored in situ in real time using optical microscopy. During growth, we measured the intensity of light emission and the reflected light from the heated microbolometer. Our measurements of bolometer performance show that the CNT layer on the surface of the microbolometer membrane increases the IR response by a factor of (2.3 ± 0.1) (mean ± one standard deviation of the least-squares fit parameters). This work opens the door to integrating near unity IR absorption, CNT-based, IR absorbers with hybrid complementary metal-oxide-semiconductor focal plane array architectures.

Oxidation of CO by NO on planar and faceted Ir(210)

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

Chen, Wenhua; Bartynski, Robert A.; Kaghazchi, Payam

2012-06-11

Oxidation of CO by pre-adsorbed NO has been studied on planar Ir(210) and nanofaceted Ir(210) with average facet sizes of 5 nm and 14 nm by temperature programmed desorption (TPD). Both surfaces favor oxidation of CO to CO 2, which is accompanied by simultaneous reduction of NO with high selectivity to N 2. At low NO pre-coverage, the temperature (T i) for the onset of CO 2 desorption as well as CO 2 desorption peak temperature (T p) decreases with increasing CO exposure, and NO dissociation is affected by co-adsorbed CO. At high NO pre-coverage, T i and T pmore » are independent of CO exposure, and co-adsorbed CO has no influence on dissociation of NO. Moreover, at low NO pre-coverage, planar Ir(210) is more active than faceted Ir(210) for oxidation of CO to CO 2: T i and T p are much lower on planar Ir(210) than that on faceted Ir(210). In addition, faceted Ir(210) with an average facet size of 5 nm is more active for oxidation of CO to CO 2 than faceted Ir(210) with an average facet size of 14 nm, i.e., oxidation of CO by pre-adsorbed NO on faceted Ir(210) exhibits size effects on the nanometer scale. In comparison, at low O pre-coverage planar Ir(210) is more active than faceted Ir(210) for oxidation of CO to CO 2 but no evidence has been found for size effects in oxidation of CO by pre-adsorbed oxygen on faceted Ir(210) for average facet sizes of 5 nm and 14 nm. The TPD data indicate the same reaction pathway for CO 2 formation from CO + NO and CO + O reactions on planar Ir(210). Lastly, the adsorption sites of CO, NO, O, CO + O, and CO + NO on Ir are characterized by density functional theory.« less

Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity

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

Cheng, Zhe; Xu, Zaoli; Xu, Shen

2015-01-14

By studying the temperature-dependent behavior (300 K down to 43 K) of electron thermal conductivity (κ) in a 3.2 nm-thin Ir film, we quantify the extremely confined defect-electron scatterings and isolate the intrinsic phonon-electron scattering that is shared by the bulk Ir. At low temperatures below 50 K, κ of the film has almost two orders of magnitude reduction from that of bulk Ir. The film has ∂κ/∂T > 0, while the bulk Ir has ∂κ/∂T < 0. We introduce a unified thermal resistivity (Θ = T/κ) to interpret these completely different κ ∼ T relations. It is found that the film and the bulk Ir share a very similar Θ ∼ T trend,more » while they have a different residual part (Θ{sub 0}) at 0 K limit: Θ{sub 0} ∼ 0 for the bulk Ir, and Θ{sub 0} = 5.5 m·K{sup 2}/W for the film. The Ir film and the bulk Ir have very close ∂Θ/∂T (75–290 K): 6.33 × 10{sup −3} m K/W for the film and 7.62 × 10{sup −3} m K/W for the bulk Ir. This strongly confirms the similar phonon-electron scattering in them. Therefore, the residual thermal resistivity provides an unprecedented way to quantitatively evaluating defect-electron scattering (Θ{sub 0}) in heat conduction. Moreover, the interfacial thermal conductance across the grain boundaries is found larger than that of Al/Cu interface, and its value is proportional to temperature, largely due to the electron's specific heat. A unified interfacial thermal conductance is also defined and firmly proves this relation. Additionally, the electron reflection coefficient is found to be large (88%) and almost temperature independent.« less

Reduction of shunt current in buffer-free IrMn based spin-valve structures

NASA Astrophysics Data System (ADS)

Kocaman, B.; Akdoğan, N.

2018-06-01

The presence of thick buffer layers in magnetic sensor devices decreases sensor sensitivity due to shunt currents. With this motivation, we produced IrMn-based spin-valve multilayers without using buffer layer. We also studied the effects of post-annealing and IrMn thickness on exchange bias field (HEB) and blocking temperature (TB) of the system. Magnetization measurements indicate that both HEB and TB values are significantly enhanced with post-annealing of IrMn layer. In addition, we report that IrMn thickness of the system strongly influences the magnetization and transport characteristics of the spin-valve structures. We found that the minimum thickness of IrMn layer is 6 nm in order to achieve the lowest shunt current and high blocking temperature (>300 K). We also investigated the training of exchange bias to check the long-term durability of IrMn-based spin-valve structures for device applications.

Metabolic Syndrome and Importance of Associated Variables in Children and Adolescents in Guabiruba - SC, Brazil

PubMed Central

Rosini, Nilton; Moura, Solange A. Z. Oppermann; Rosini, Rodrigo Diegoli; Machado, Marcos José; da Silva, Edson Luiz

2015-01-01

Background The risk factors that characterize metabolic syndrome (MetS) may be present in childhood and adolescence, increasing the risk of cardiovascular disease in adulthood. Objective Evaluate the prevalence of MetS and the importance of its associated variables, including insulin resistance (IR), in children and adolescents in the city of Guabiruba-SC, Brazil. Methods Cross-sectional study with 1011 students (6-14 years, 52.4% girls, 58.5% children). Blood samples were collected for measurement of biochemical parameters by routine laboratory methods. IR was estimated by the HOMA-IR index, and weight, height, waist circumference and blood pressure were determined. Multivariate logistic regression models were used to examine the associations between risk variables and MetS. Results The prevalence of MetS, IR, overweight and obesity in the cohort were 14%, 8.5%, 21% and 13%, respectively. Among students with MetS, 27% had IR, 33% were overweight, 45.5% were obese and 22% were eutrophic. IR was more common in overweight (48%) and obese (41%) students when compared with eutrophic individuals (11%; p = 0.034). The variables with greatest influence on the development of MetS were obesity (OR = 32.7), overweight (OR = 6.1), IR (OR = 4.4; p ≤ 0.0001 for all) and age (OR = 1.15; p = 0.014). Conclusion There was a high prevalence of MetS in children and adolescents evaluated in this study. Students who were obese, overweight or insulin resistant had higher chances of developing the syndrome. PMID:25993484

Phase diagram and electrical behavior of silicon-rich iridium silicide compounds

NASA Technical Reports Server (NTRS)

Allevato, C. E.; Vining, Cronin B.

1992-01-01

The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis, metalography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only four distinct compositions: IrSi, Ir3Si4, Ir3Si5 and IrSi sub about 3. The existence of Ir4Si5 could not be confirmed in this study, even though the crystal structure has been previously reported. Differential thermal analysis (DTA) in conjunction with X-ray powder diffraction confirm polymorphism in IrSi sub about 3, determined to have orthorhombic and monoclinic unit cells in the high and low temperature forms. A eutectic composition alloy of 83 +/- 1 atomic percent silicon was observed between IrSi sub about 3 and silicon. Ir3Si4 exhibits distinct metallic behavior while Ir3Si5 is semiconducting. Both and IrSi and IrSi sub about 3 exhibit nearly temperature independent electrical resistivities on the order of 5-10 x 10 exp -6 ohms-m.

Analysis of intraspecific seed diversity in Astragalus aquilanus (Fabaceae), an endemic species of Central Apennine.

PubMed

Di Cecco, V; Di Musciano, M; D'Archivio, A A; Frattaroli, A R; Di Martino, L

2018-05-20

This work aims to study seeds of the endemic species Astragalus aquilanus from four different populations of central Italy. We investigated seed morpho-colorimetric features (shape and size) and chemical differences (through infrared spectroscopy) among populations and between dark and light seeds. Seed morpho-colorimetric quantitative variables, describing shape, size and colour traits, were measured using image analysis techniques. Fourier transform infrared (FT-IR) spectroscopy was used to attempt seed chemical characterisation. The measured data were analysed by step-wise linear discriminant analysis (LDA). Moreover, we analysed the correlation between the four most important traits and six climatic variables extracted from WorldClim 2.0. The LDA on seeds traits shows clear differentiation of the four populations, which can be attributed to different chemical composition, as confirmed by Wilk's lambda test (P < 0.001). A strong correlation between morphometric traits and temperature (annual mean temperature, mean temperature of the warmest and coolest quarter), colorimetric traits and precipitation (annual precipitation, precipitation of wettest and driest quarter) was observed. The characterisation of A. aquilanus seeds shows large intraspecific plasticity both in morpho-colorimetric and chemical composition. These results confirm the strong relationship between the type of seed produced and the climatic variables. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

[Determination of the content of sulfur of coal by the infrared absorption method with high acccuracy].

PubMed

Wang, Hai-Feng; Lu, Hai; Li, Jia; Sun, Guo-Hua; Wang, Jun; Dai, Xin-Hua

2014-02-01

The present paper reported the differential scanning calorimetry-thermogravimetry curves and the infrared (IR) absorption spectrometry under the temperature program analyzed by the combined simultaneous thermal analysis-IR spectrometer. The gas products of coal were identified by the IR spectrometry. This paper emphasized on the combustion at high temperature-IR absorption method, a convenient and accurate method, which measures the content of sulfur in coal indirectly through the determination of the content of sulfur dioxide in the mixed gas products by IR absorption. It was demonstrated, when the instrument was calibrated by varied pure compounds containing sulfur and certified reference materials (CRMs) for coal, that there was a large deviation in the measured sulfur contents. It indicates that the difference in chemical speciations of sulfur between CRMs and the analyte results in a systematic error. The time-IR absorption curve was utilized to analyze the composition of sulfur at low temperatures and high temperatures and then the sulfur content of coal sample was determined by using a CRM for coal with a close composition of sulfur. Therefore, the systematic error due to the difference in chemical speciations of sulfur between the CRM and analyte was eliminated. On the other hand, in this combustion at high temperature-IR absorption method, the mass of CRM and analyte were adjusted to assure the sulfur mass equal and then the CRM and the analyte were measured alternately. This single-point calibration method reduced the effect of the drift of the IR detector and improved the repeatability of results, compared with the conventional multi-point calibration method using the calibration curves of signal intensity vs sulfur mass. The sulfur content results and their standard deviations of an anthracite coal and a bituminous coal with a low sulfur content determined by this modified method were 0.345% (0.004%) and 0.372% (0.008%), respectively. The uncertainty (U, k =2) of sulfur contents of two coal samples was evaluated to be 0.019% and 0.021%, respectively. Two main modifications, namely the calibration using the coal CRM with a similar composition of low-temperature sulfur and high temperature sulfur, and the single-point calibration alternating CRM and analyte, endow the combustion at high temperature-IR absorption method with an accuracy obviously better than that of the ASTM method. Therefore, this modified method has a well potential in the analysis of sulfur content.

Measurement of Two-Phase Flow and Heat Transfer Parameters using Infrared Thermometry

NASA Technical Reports Server (NTRS)

Kim, Tae-Hoon; Kommer, Eric; Dessiatoun, Serguei; Kim, Jungho

2012-01-01

A novel technique to measure heat transfer and liquid film thickness distributions over relatively large areas for two-phase flow and heat transfer phenomena using infrared (IR)thermometry is described. IR thermometry is an established technology that can be used to measure temperatures when optical access to the surface is available in the wavelengths of interest. In this work, a midwave IR camera (3.6-5.1 microns) is used to determine the temperature distribution within a multilayer consisting of a silicon substrate coated with a thin insulator. Since silicon is largely transparent to IR radiation, the temperature of the inner and outer walls of the multilayer can be measured by coating selected areas with a thin, IR opaque film. If the fluid used is also partially transparent to IR, the flow can be visualized and the liquid film thickness can be measured. The theoretical basis for the technique is given along with a description of the test apparatus and data reduction procedure. The technique is demonstrated by determining the heat transfer coefficient distributions produced by droplet evaporation and flow boiling heat transfer.

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

Li, Cui-Ping; Nie, Li; College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009

A new salt [H{sub 2}DABCO][Pt(mnt){sub 2}]{sub 2} (1) (mnt{sup 2-}=maleonitriledithiolate and H{sub 2}DABCO{sup 2+} is diprotonated 1,4-diazabicyclo[2.2.2]octane) has been synthesized; its crystal structure, magnetic and near-IR absorption properties have been investigated. Two different [Pt(mnt){sub 2}]{sup -} anions form the strong π-dimers, labeled as Pt(1)-dimer and Pt(2)-dimer, with quite shorter Pt…Pt and S…S distances and molecular plane-to-plane distance (<3.5 Å) within a dimer. The [Pt(mnt){sub 2}]{sub 2}{sup 2-} π-dimers are connected through the cations in the strong H-bond manner to form three-dimensional H-bond supramolecular crystal. The salt shows weak paramagnetism in 1.99–300 K and this is due to the existence ofmore » strong antiferromagnetic coupling within a π-dimer. In addition, a small thermal hysteresis loop is observed at ca. 120 K, indicating that a phase transition probably occurs that is further confirmed by variable-temperature IR spectra. Another fascinating functionality of 1 is the intense near-IR absorption in the region of 750–2500 nm, and this near-IR absorption feature makes it to be a promising optical material. - Graphical abstract: A H-bond supramolecular crystal of [H{sub 2}DABCO][Pt(mnt){sub 2}]{sub 2} shows a magnetic phase transition at ca. 120 K with sizable thermal hysteresis loop and intense near-IR absorption in the region of 750–2500 nm.« less

Long-lived room-temperature deep-red-emissive intraligand triplet excited state of naphthalimide in cyclometalated Ir(III) complexes and its application in triplet-triplet annihilation-based upconversion.

PubMed

Sun, Jifu; Wu, Wanhua; Zhao, Jianzhang

2012-06-25

Cyclometalated Ir(III) complexes with acetylide ppy and bpy ligands were prepared (ppy = 2-phenylpyridine, bpy = 2,2'-bipyridine) in which naphthal (Ir-2) and naphthalimide (NI) were attached onto the ppy (Ir-3) and bpy ligands (Ir-4) through acetylide bonds. [Ir(ppy)(3)] (Ir-1) was also prepared as a model complex. Room-temperature phosphorescence was observed for the complexes; both neutral and cationic complexes Ir-3 and Ir-4 showed strong absorption in the visible range (ε=39,600  M(-1)  cm(-1) at 402 nm and ε=25,100  M(-1)  cm(-1) at 404 nm, respectively), long-lived triplet excited states (τ(T)=9.30 μs and 16.45 μs) and room-temperature red emission (λ(em)=640 nm, Φ(p)=1.4 % and λ(em)=627 nm, Φ(p)=0.3 %; cf. Ir-1: ε=16,600  M(-1)  cm(-1) at 382 nm, τ(em)=1.16 μs, Φ(p)=72.6 %). Ir-3 was strongly phosphorescent in non-polar solvent (i.e., toluene), but the emission was completely quenched in polar solvents (MeCN). Ir-4 gave an opposite response to the solvent polarity, that is, stronger phosphorescence in polar solvents than in non-polar solvents. Emission of Ir-1 and Ir-2 was not solvent-polarity-dependent. The T(1) excited states of Ir-2, Ir-3, and Ir-4 were identified as mainly intraligand triplet excited states ((3)IL) by their small thermally induced Stokes shifts (ΔE(s)), nanosecond time-resolved transient difference absorption spectroscopy, and spin-density analysis. The complexes were used as triplet photosensitizers for triplet-triplet annihilation (TTA) upconversion and quantum yields of 7.1 % and 14.4 % were observed for Ir-2 and Ir-3, respectively, whereas the upconversion was negligible for Ir-1 and Ir-4. These results will be useful for designing visible-light-harvesting transition-metal complexes and for their applications as triplet photosensitizers for photocatalysis, photovoltaics, TTA upconversion, etc. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Upper wide-angle viewing system for ITER.

PubMed

Lasnier, C J; McLean, A G; Gattuso, A; O'Neill, R; Smiley, M; Vasquez, J; Feder, R; Smith, M; Stratton, B; Johnson, D; Verlaan, A L; Heijmans, J A C

2016-11-01

The Upper Wide Angle Viewing System (UWAVS) will be installed on five upper ports of ITER. This paper shows major requirements, gives an overview of the preliminary design with reasons for some design choices, examines self-emitted IR light from UWAVS optics and its effect on accuracy, and shows calculations of signal-to-noise ratios for the two-color temperature output as a function of integration time and divertor temperature. Accurate temperature output requires correction for vacuum window absorption vs. wavelength and for self-emitted IR, which requires good measurement of the temperature of the optical components. The anticipated signal-to-noise ratio using presently available IR cameras is adequate for the required 500 Hz frame rate.

Validation of Infrared Azimuthal Model as Applied to GOES Data Over the ARM SGP

NASA Technical Reports Server (NTRS)

Gambheer, Arvind V.; Doelling, David R.; Spangenberg, Douglas A.; Minnis, Patrick

2004-01-01

The goal of this research is to identify and reduce the GOES-8 IR temperature biases, induced by a fixed geostationary position, during the course of a day. In this study, the same CERES LW window channel model is applied to GOES-8 IR temperatures during clear days over the Atmospheric Radiation Measurement-Southern Great Plains Central Facility (SCF). The model-adjusted and observed IR temperatures are compared with topof- the-atmosphere (TOA) estimated temperatures derived from a radiative transfer algorithm based on the atmospheric profile and surface radiometer measurements. This algorithm can then be incorporated to derive more accurate Ts from real-time satellite operational products.

Metabolic effects of resistance or high-intensity interval training among glycemic control-nonresponsive children with insulin resistance.

PubMed

Álvarez, C; Ramírez-Campillo, R; Ramírez-Vélez, R; Martínez, C; Castro-Sepúlveda, M; Alonso-Martínez, A; Izquierdo, M

2018-01-01

Little evidence exists on which variables of body composition or muscular strength mediates more glucose control improvements taking into account inter-individual metabolic variability to different modes of exercise training. We examined 'mediators' to the effects of 6-weeks of resistance training (RT) or high-intensity interval training (HIT) on glucose control parameters in physically inactive schoolchildren with insulin resistance (IR). Second, we also determined both training-induce changes and the prevalence of responders (R) and non-responders (NR) to decrease the IR level. Fifty-six physically inactive children diagnosed with IR followed a RT or supervised HIT program for 6 weeks. Participants were classified based on ΔHOMA-IR into glycemic control R (decrease in homeostasis model assessment-IR (HOMA-IR) <3.0 after intervention) and NRs (no changes or values HOMA-IR⩾3.0 after intervention). The primary outcome was HOMA-IR associated with their mediators; second, the training-induced changes to glucose control parameters; and third the report of R and NR to improve body composition, cardiovascular, metabolic and performance variables. Mediation analysis revealed that improvements (decreases) in abdominal fat by the waist circumference can explain more the effects (decreases) of HOMA-IR in physically inactive schoolchildren under RT or HIT regimes. The same analysis showed that increased one-maximum repetition leg-extension was correlated with the change in HOMA-IR (β=-0.058; P=0.049). Furthermore, a change in the waist circumference fully mediated the dose-response relationship between changes in the leg-extension strength and HOMA-IR (β'=-0.004; P=0.178). RT or HIT were associated with significant improvements in body composition, muscular strength, blood pressure and cardiometabolic parameters irrespective of improvement in glycemic control response. Both glucose control RT-R and HIT-R (respectively), had significant improvements in mean HOMA-IR, mean muscular strength leg-extension and mean measures of adiposity. The improvements in the lower body strength and the decreases in waist circumference can explain more the effects of the improvements in glucose control of IR schoolchildren in R group after 6 weeks of RT or HIT, showing both regimes similar effects on body composition or muscular strength independent of interindividual metabolic response variability.

Iridium-Coated Rhenium Radiation-Cooled Rockets

NASA Technical Reports Server (NTRS)

Reed, Brian D.; Biaglow, James A.; Schneider, Steven J.

1997-01-01

Radiation-cooled rockets are used for a range of low-thrust propulsion functions, including apogee insertion, attitude control, and repositioning of satellites, reaction control of launch vehicles, and primary propulsion for planetary space- craft. The key to high performance and long lifetimes for radiation-cooled rockets is the chamber temperature capability. The material system that is currently used for radiation-cooled rockets, a niobium alloy (C103) with a fused silica coating, has a maximum operating temperature of 1370 C. Temperature limitations of C103 rockets force the use of fuel film cooling, which degrades rocket performance and, in some cases, imposes a plume contamination issue from unburned fuel. A material system composed of a rhenium (Re) substrate and an iridium (Ir) coating has demonstrated operation at high temperatures (2200 C) and for long lifetimes (hours). The added thermal margin afforded by iridium-coated rhenium (Ir/Re) allows reduction or elimination of fuel film cooling. This, in turn, leads to higher performance and cleaner spacecraft environments. There are ongoing government- and industry-sponsored efforts to develop flight Ir/ Re engines, with the primary focus on 440-N, apogee insertion engines. Complementing these Ir/Re engine development efforts is a program to address specific concerns and fundamental characterization of the Ir/Re material system, including (1) development of Ir/Re rocket fabrication methods, (2) establishment of critical Re mechanical properly data, (3) development of reliable joining methods, and (4) characterization of Ir/Re life-limiting mechanisms.

A non-invasive experimental approach for surface temperature measurements on semi-crystalline thermoplastics

NASA Astrophysics Data System (ADS)

Boztepe, Sinan; Gilblas, Remi; de Almeida, Olivier; Le Maoult, Yannick; Schmidt, Fabrice

2017-10-01

Most of the thermoforming processes of thermoplastic polymers and their composites are performed adopting a combined heating and forming stages at which a precursor is heated prior to the forming. This step is done in order to improve formability by softening the thermoplastic polymer. Due to low thermal conductivity and semi-transparency of polymers, infrared (IR) heating is widely used for thermoforming of such materials. Predictive radiation heat transfer models for temperature distributions are therefore critical for optimizations of thermoforming process. One of the key challenges is to build a predictive model including the physical background of radiation heat transfer phenomenon in semi-crystalline thermoplastics as their microcrystalline structure introduces an optically heterogeneous medium. In addition, the accuracy of a predictive model is required to be validated experimentally where IR thermography is one of the suitable methods for such a validation as it provides a non-invasive, full-field surface temperature measurement. Although IR cameras provide a non-invasive measurement, a key issue for obtaining a reliable measurement depends on the optical characteristics of a heated material and the operating spectral band of IR camera. It is desired that the surface of a material to be measured has a spectral band where the material behaves opaque and an employed IR camera operates in the corresponding band. In this study, the optical characteristics of the PO-based polymer are discussed and, an experimental approach is proposed in order to measure the surface temperature of the PO-based polymer via IR thermography. The preliminary analyses showed that IR thermographic measurements may not be simply performed on PO-based polymers and require a correction method as their semi-transparent medium introduce a challenge to obtain reliable surface temperature measurements.

IR photometry and models for the dust shells of two oxygen Mira variables

NASA Astrophysics Data System (ADS)

Bogdanov, M. B.; Taranova, O. G.; Shenavrin, V. I.

2015-05-01

Long-term JHKLM photometric measurements of the oxygen Mira variables RU Her and RS Vir are presented. Variations of the brightnesses and colors of these stars over the observation period are analyzed, and master light curves and color indices of these stars are derived. A linear trend was present in the mean infrared brightness of RS Vir on a time scale of ˜6000 day, possibly related to changes in the dust shell of the Mira. The results of model calculations of spherically symmetric dust shells of stars based on mean-flux data supplemented by observations from the IRAS and AKARI satellites in the intermediate- and far-IR are presented. The visual optical depth of the dust shell of RU Her, which has a temperature at its inner boundary T 1 = 590 K, is quite low: τ V = 0.33. The dust shell of RS Vir is much cooler ( T 1 = 410 K), and has τ V = 0.77. The estimated mass-loss rate of RU Her is 6.2 × 10-7 M ⊙/yr, while the mass-loss rate of RS Vir is 7.1 × 10-7 M ⊙/yr.

Infrared spectroscopic studies of the effect of elevated temperature on the association of pyroglutamic acid with clay and other minerals

NASA Astrophysics Data System (ADS)

Macklin, John W.; White, David H.

Fourier transform i.r. measurements of L-pyroglutamic acid dispersed in a matrix of a clay, silica or alumina have been obtained at various temperatures between 25 and 220°C. The i.r. spectrum of L-pyroglutamic acid varies in a manner slightly dependent upon the matrix material and shows considerable change as the temperature of the mixtures is increased. The differences in the spectrum at elevated temperatures are explained in terms of a chemical reaction between hydroxyl groups in the matrix and the carboxylic acid. The i.r. spectra of trimethylsilyl derivatives of L-pyroglutamic acid and aluminum pyroglutamate were also measured to assist the understanding of spectra and interpretation of the spectral changes dependent upon increasing temperature.

Infrared spectroscopic studies of the effect of elevated temperature on the association of pyroglutamic acid with clay and other minerals

NASA Technical Reports Server (NTRS)

Macklin, J. W.; White, D. H.

1985-01-01

Fourier transform i.r. measurements of L-pyroglutamic acid dispersed in a matrix of a clay, silica or alumina have been obtained at various temperatures between 25 and 220 degrees C. The i.r. spectrum of L-pyroglutamic acid varies in a manner dependent upon the matrix material and shows considerable change as the temperature of the mixtures is increased. The differences in the spectrum at elevated temperatures are explained in terms of a chemical reaction between hydroxyl groups in the matrix and the carboxylic acid. The i.r. spectra of trimethylsilyl derivatives of L-pyroglutamic acid and aluminum pyroglutamate were also measured to assist the understanding of spectra and interpretation of the spectral changes dependent upon increasing temperature.

Validation of the thermal code of RadTherm-IR, IR-Workbench, and F-TOM

NASA Astrophysics Data System (ADS)

Schwenger, Frédéric; Grossmann, Peter; Malaplate, Alain

2009-05-01

System assessment by image simulation requires synthetic scenarios that can be viewed by the device to be simulated. In addition to physical modeling of the camera, a reliable modeling of scene elements is necessary. Software products for modeling of target data in the IR should be capable of (i) predicting surface temperatures of scene elements over a long period of time and (ii) computing sensor views of the scenario. For such applications, FGAN-FOM acquired the software products RadTherm-IR (ThermoAnalytics Inc., Calumet, USA; IR-Workbench (OKTAL-SE, Toulouse, France). Inspection of the accuracy of simulation results by validation is necessary before using these products for applications. In the first step of validation, the performance of both "thermal solvers" was determined through comparison of the computed diurnal surface temperatures of a simple object with the corresponding values from measurements. CUBI is a rather simple geometric object with well known material parameters which makes it suitable for testing and validating object models in IR. It was used in this study as a test body. Comparison of calculated and measured surface temperature values will be presented, together with the results from the FGAN-FOM thermal object code F-TOM. In the second validation step, radiances of the simulated sensor views computed by RadTherm-IR and IR-Workbench will be compared with radiances retrieved from the recorded sensor images taken by the sensor that was simulated. Strengths and weaknesses of the models RadTherm-IR, IR-Workbench and F-TOM will be discussed.

Infrared target simulation environment for pattern recognition applications

NASA Astrophysics Data System (ADS)

Savakis, Andreas E.; George, Nicholas

1994-07-01

The generation of complete databases of IR data is extremely useful for training human observers and testing automatic pattern recognition algorithms. Field data may be used for realism, but require expensive and time-consuming procedures. IR scene simulation methods have emerged as a more economical and efficient alternative for the generation of IR databases. A novel approach to IR target simulation is presented in this paper. Model vehicles at 1:24 scale are used for the simulation of real targets. The temperature profile of the model vehicles is controlled using resistive circuits which are embedded inside the models. The IR target is recorded using an Inframetrics dual channel IR camera system. Using computer processing we place the recorded IR target in a prerecorded background. The advantages of this approach are: (1) the range and 3D target aspect can be controlled by the relative position between the camera and model vehicle; (2) the temperature profile can be controlled by adjusting the power delivered to the resistive circuit; (3) the IR sensor effects are directly incorporated in the recording process, because the real sensor is used; (4) the recorded target can embedded in various types of backgrounds recorded under different weather conditions, times of day etc. The effectiveness of this approach is demonstrated by generating an IR database of three vehicles which is used to train a back propagation neural network. The neural network is capable of classifying vehicle type, vehicle aspect, and relative temperature with a high degree of accuracy.

RADIO MONITORING OF THE PERIODICALLY VARIABLE IR SOURCE LRLL 54361: NO DIRECT CORRELATION BETWEEN THE RADIO AND IR EMISSIONS

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

Forbrich, Jan, E-mail: jan.forbrich@univie.ac.at; Rodríguez, Luis F.; Palau, Aina

2015-11-20

LRLL 54361 is an infrared source located in the star-forming region IC 348 SW. Remarkably, its infrared luminosity increases by a factor of 10 over roughly one week every 25.34 days. To understand the origin of these remarkable periodic variations, we obtained sensitive 3.3 cm JVLA radio continuum observations of LRLL 54361 and its surroundings in six different epochs: three of them during the IR-on state and three during the IR-off state. The radio source associated with LRLL 54361 remained steady and did not show a correlation with the IR variations. We suggest that the IR is tracing the resultsmore » of fast (with a timescale of days) pulsed accretion from an unseen binary companion, while the radio traces an ionized outflow with an extent of ∼100 AU that smooths out the variability over a period of the order of a year. The average flux density measured in these 2014 observations, 27 ± 5 μJy, is about a factor of two less than that measured about 1.5 years before, 53 ± 11 μJy, suggesting that variability in the radio is present, but over larger timescales than in the IR. We discuss other sources in the field, in particular two infrared/X-ray stars that show rapidly varying gyrosynchrotron emission.« less

Satellite Infrared Radiation Measurements Prior to the Major Earthquakes

NASA Technical Reports Server (NTRS)

Ouzounov, Dimitar; Pulintes, S.; Bryant, N.; Taylor, Patrick; Freund, F.

2005-01-01

This work describes our search for a relationship between tectonic stresses and increases in mid-infrared (IR) flux as part of a possible ensemble of electromagnetic (EM) phenomena that may be related to earthquake activity. We present and &scuss observed variations in thermal transients and radiation fields prior to the earthquakes of Jan 22, 2003 Colima (M6.7) Mexico, Sept. 28 .2004 near Parkfield (M6.0) in California and Northern Sumatra (M8.5) Dec. 26,2004. Previous analysis of earthquake events has indicated the presence of an IR anomaly, where temperatures increased or did not return to its usual nighttime value. Our procedures analyze nighttime satellite data that records the general condtion of the ground after sunset. We have found from the MODIS instrument data that five days before the Colima earthquake the IR land surface nighttime temperature rose up to +4 degrees C in a 100 km radius around the epicenter. The IR transient field recorded by MODIS in the vicinity of Parkfield, also with a cloud free environment, was around +1 degree C and is significantly smaller than the IR anomaly around the Colima epicenter. Ground surface temperatures near the Parkfield epicenter four days prior to the earthquake show steady increase. However, on the night preceding the quake, a significant drop in relative humidity was indicated, process similar to those register prior to the Colima event. Recent analyses of continuous ongoing long- wavelength Earth radiation (OLR) indicate significant and anomalous variability prior to some earthquakes. The cause of these anomalies is not well understood but could be the result of a triggering by an interaction between the lithosphere-hydrosphere and atmospheric related to changes in the near surface electrical field and/or gas composition prior to the earthquake. The OLR anomaly usually covers large areas surrounding the main epicenter. We have found strong anomalies signal (two sigma) along the epicentral area signals on Dec 21, five days prior to the Northern Sumatra quake compared to the reference field for December 2001-2004 periods. Our recent results support the hypothesis of a possible relationship between a thermodynamic processes produced by increasing tectonic stress in the Earth's crust and a subsequent electro-chemical interaction between this crust and the atmosphere/ionosphere.

Film Condensation of Steam on Externally Finned Horizontal Tubes.

DTIC Science & Technology

1985-03-01

Thermal Conductivity of Tube/Fin Metal i" ir - Condensation Rate Nu - Nusselt Number PA’ PB’ PC - Pressure at Points A, B, and C in Figure 2.1 APAB’ PcB...single finned tubes. To predict the film coefficients, they started with the Nusselt equations for condensation on a horizontal tube and on a vertical... Nusselt equation was obtained. A " condensation efficiency" was then proposed to account for a variable fin temperature, and was defined as: C, F1 (2.18) 3

Structure and thermal decomposition of sulfated β-cyclodextrin intercalated in a layered double hydroxide

NASA Astrophysics Data System (ADS)

Wang, Ji; Wei, Min; Rao, Guoying; Evans, David G.; Duan, Xue

2004-01-01

The sodium salt of hexasulfated β-cyclodextrin has been synthesized and intercalated into a magnesium-aluminum layered double hydroxide by ion exchange. The structure, composition and thermal decomposition behavior of the intercalated material have been studied by variable temperature X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma emission spectroscopy (ICP), and thermal analysis (TG-DTA) and a model for the structure has been proposed. The thermal stability of the intercalated sulfated β-cyclodextrin is significantly enhanced compared with the pure form before intercalation.

Large enhancement of Blocking temperature by control of interfacial structures in Pt/NiFe/IrMn/MgO/Pt multilayers

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

Chen, Xi; Wang, Shouguo, E-mail: sgwang@ustb.edu.cn; Han, Gang

2015-09-15

The Blocking temperature (T{sub B}) of Pt/NiFe/IrMn/MgO/Pt multilayers was greatly enhanced from far below room temperature (RT) to above RT by inserting 1 nm thick Mg layer at IrMn/MgO interface. Furthermore, the exchange bias field (H{sub eb}) was increased as well by the control of interfacial structures. The evidence for a significant fraction of Mn-O bonding at IrMn/MgO interface without Mg insertion layer was provided by X-ray photoelectron spectroscopy. The bonding between Mn and O can decrease the antiferromagnetism of IrMn film, leading to lower value of T{sub B} in Pt/NiFe/IrMn/MgO/Pt multilayers. Ultrathin Mg film inserted at IrMn/MgO interface actingmore » as an oxygen sinking layer can suppress the oxidation reactions between Mn and O and reduce the formation of Mn-O bonding greatly. The oxidation suppression results in the recovery of the antiferromagnetism of IrMn film, which can enhance T{sub B} and H{sub eb}. Furthermore, the high resolution transmission electron microscopy demonstrates that the Mg insertion layer can efficiently promote a high-quality MgO (200) texture. This study will enhance the understanding of physics in antiferromagnet-based spintronic devices.« less

Structural, electronic and magnetic properties of the series of double perovskites (Ca , Sr) 2 - xLaxFeIrO6

NASA Astrophysics Data System (ADS)

Bufaiçal, L.; Adriano, C.; Lora-Serrano, R.; Duque, J. G. S.; Mendonça-Ferreira, L.; Rojas-Ayala, C.; Baggio-Saitovitch, E.; Bittar, E. M.; Pagliuso, P. G.

2014-04-01

Polycrystalline samples of the series of double perovskites Sr2-xLaxFeIrO6 were synthesized. Their structural, electronic and magnetic properties were investigated by X-ray powder diffraction, Mössbauer spectroscopy, magnetic susceptibility, heat capacity and electrical resistivity experiments. The compounds crystallize in a monoclinic structure and were fitted in space group P21 / n, with a significant degree of Fe/Ir cationic disorder. As in Ca2-xLaxFeIrO6 the Sr-based system seems to evolve from an antiferromagnetic ground state for the end members (x=0.0 and x=2.0) to a ferrimagnetic order in the intermediate regions (x ~ 1). Since Mössbauer spectra indicate that Fe valence remains 3+ with doping, this tendency of change in the nature of the microscopic interaction could be attributed to Ir valence changes, induced by La3+ electrical doping. Upon comparing both Ca and Sr series, Sr2-xLaxFeIrO6 is more structurally homogenous and presents higher magnetization and transition temperatures. Magnetic susceptibility measurements at high temperatures on Sr1.2La0.8FeIrO6 indicate a very high ferrimagnetic Curie temperature TC ~ 700 K. For the Sr2FeIrO6 compound, electrical resistivity experiments under applied pressure suggest that this material might be a Mott insulator.

Experimental investigation of passive infrared ice detection for helicopter applications

NASA Technical Reports Server (NTRS)

Dershowitz, Adam; Hansman, R. John, Jr.

1991-01-01

A technique is proposed to remotely detect rotor icing on helicopters. Using passive infrared (IR) thermometry it is possible to detect the warming caused by latent heat released as supercooled water freezes. During icing, the ice accretion region on the blade leading edge will be warmer than the uniced trailing edge resulting in a chordwise temperature profile characteristic of icing. Preliminary tests were conducted on a static model in the NASA Icing Research Tunnel for a variety of wet (glaze) and dry (rime) ice conditions. The characteristic chordwise temperature profiles were observed with an IR thermal video system and confirmed with thermocouple measurements. A prototype detector system was built consisting of a single point IR pyrometer, and experiments were run on a small scale rotor model. Again the characteristic chordwise temperature profiles were observed during icing, and the IR system was able to remotely detect icing. Based on the static and subscale rotor tests the passive IR technique is promising for rotor ice detection.

Experimental investigation of passive infrared ice detection for helicopter applications

NASA Technical Reports Server (NTRS)

Dershowitz, Adam; Hansman, R. John, Jr.

1991-01-01

A technique is proposed to remotely detect rotor icing on helicopters. Using passive infrared (IR) thermometry, it is possible to detect the warming caused by latent heat released as supercooled water freezes. During icing, the ice accretion region on the blade leading edge will be warmer than the uniced trailing edge, resulting in a chordwise temperature profile characteristic of icing. Preliminary tests were conducted on a static model in the NASA Icing Research Tunnel for a variety of wet (glaze) and dry (rime) ice conditions. The characteristic chordwise temperature profiles were observed with an IR thermal video system and confirmed with thermocouple measurements. A prototype detector system was built consisting of a single point IR pyrometer. Experiments were run on a small scale rotor model. Again, the characteristic chordwise temperature profiles were observed during icing, and the IR system was able to remotely detect icing. Based on the static and subscale rotor tests, the passive IR technique is promising for rotor ice detection.

Experimental determination of the Fermi surface of Sr3Ir4Sn13

NASA Astrophysics Data System (ADS)

Chen, Xiaoye; Goh, Swee K.; Tompsett, David A.; Yu, Wing Chi; Klintberg, Lina; Friedemann, Sven; Tan, Hong'En; Yang, Jinhu; Chen, Bin; Imai, M.; Yoshimura, Kazuyoshi; Gamza, Monika B.; Grosche, F. Malte; Sutherland, Michael L.

2016-06-01

The stannide family of materials A3T4 Sn13 (A =La ,Sr ,Ca ; T =Ir ,Rh ) is interesting due to the interplay between a tunable lattice instability and phonon-mediated superconductivity with Tc˜5 -7 K . In Sr3Ir4Sn13, a structural transition temperature T˜147 K associated with this instability has been reported, which is believed to result from a superlattice distortion of the high-temperature phase on cooling. Here we report an experimental study of the electronic structure of a member of this material family, Sr3Ir4Sn13, through measurements of quantum oscillations and comparison with density functional theory calculations. Our measurements reveal good agreement with theory using the lattice parameters consistent with a body-centered-cubic lattice of symmetry I 4 ¯3 d of the low-temperature phase. The study of the fermiology of Sr3Ir4Sn13 that we present here should help inform models of multiband superconductivity in the superconducting stannides.

Cloud cover over the equatorial eastern Pacific derived from July 1983 International Satellite Cloud Climatology Project data using a hybrid bispectral threshold method

NASA Technical Reports Server (NTRS)

Minnis, Patrick; Harrison, Edwin F.; Gibson, Gary G.

1987-01-01

A set of visible and IR data obtained with GOES from July 17-31, 1983 is analyzed using a modified version of the hybrid bispectral threshold method developed by Minnis and Harrison (1984). This methodology can be divided into a set of procedures or optional techniques to determine the proper contaminate clear-sky temperature or IR threshold. The various optional techniques are described; the options are: standard, low-temperature limit, high-reflectance limit, low-reflectance limit, coldest pixel and thermal adjustment limit, IR-only low-cloud temperature limit, IR clear-sky limit, and IR overcast limit. Variations in the cloud parameters and the characteristics and diurnal cycles of trade cumulus and stratocumulus clouds over the eastern equatorial Pacific are examined. It is noted that the new method produces substantial changes in about one third of the cloud amount retrieval; and low cloud retrievals are affected most by the new constraints.

Lack of Association between Hepatitis C Virus core Gene Variation 70/91aa and Insulin Resistance.

PubMed

Scalioni, Letícia de Paula; da Silva, Allan Peres; Miguel, Juliana Custódio; Espírito Santo, Márcia Paschoal do; Marques, Vanessa Alves; Brandão-Mello, Carlos Eduardo; Villela-Nogueira, Cristiane Alves; Lewis-Ximenez, Lia Laura; Lampe, Elisabeth; Villar, Livia Melo

2017-07-21

The role of hepatitis C virus (HCV) in insulin resistance (IR) is not fully understood. The aim of this study was to determine the impact of amino acid (aa) substitutions in the core region of HCV according to IR and to identify clinical and laboratory associations. Ninety-two treatment-naive HCV patients were recruited to determine laboratory data and blood cell count. IR was determined using Homeostasis Model Assessment (HOMA) index where IR was defined as HOMA ≥2. HCV RNA load and genotype were determined by Abbott Real time HCV. HCV core region was determined by direct nucleotide sequencing. Bivariate analysis was conducted using HOMA IR ≥2 as a dependent factor. IR prevalence was 43.5% ( n = 40), vitamin D sufficiency was found in 76.1% ( n = 70) and 72.8% ( n = 67) had advanced liver fibrosis. In the bivariate analyses, elevated values of γGT ( p = 0.024) and fibrosis staging ( p = 0.004) were associated with IR, but IR was not related to core mutations. The presence of glutamine in position 70 was associated with low vitamin D concentration ( p = 0.005). In the multivariate analysis, no variable was independently associated with HOMA-IR. In conclusion, lack of association between IR and HCV core mutations in positions 70 and 91 suggests that genetic variability of this region has little impact on IR.

Thermal Image Sensing Model for Robotic Planning and Search.

PubMed

Castro Jiménez, Lídice E; Martínez-García, Edgar A

2016-08-08

This work presents a search planning system for a rolling robot to find a source of infra-red (IR) radiation at an unknown location. Heat emissions are observed by a low-cost home-made IR passive visual sensor. The sensor capability for detection of radiation spectra was experimentally characterized. The sensor data were modeled by an exponential model to estimate the distance as a function of the IR image's intensity, and, a polynomial model to estimate temperature as a function of IR intensities. Both theoretical models are combined to deduce a subtle nonlinear exact solution via distance-temperature. A planning system obtains feed back from the IR camera (position, intensity, and temperature) to lead the robot to find the heat source. The planner is a system of nonlinear equations recursively solved by a Newton-based approach to estimate the IR-source in global coordinates. The planning system assists an autonomous navigation control in order to reach the goal and avoid collisions. Trigonometric partial differential equations were established to control the robot's course towards the heat emission. A sine function produces attractive accelerations toward the IR source. A cosine function produces repulsive accelerations against the obstacles observed by an RGB-D sensor. Simulations and real experiments of complex indoor are presented to illustrate the convenience and efficacy of the proposed approach.

Entrained-flow gasifier and fluidized-bed combustor temperature monitoring using arrays of fs-IR written fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Walker, Robert B.; Ding, Huimin; Coulas, David; Grobnic, Dan; Mihailov, Stephen J.; Duchesne, Marc A.; Hughes, Robin W.; McCalden, David J.; Burchat, Ryan

2015-09-01

Femtosecond written fiber Bragg gratings, have shown great potential for sensing in extreme environments. This paper discusses the fabrication and deployment of several fs-IR written FBG arrays, for monitoring main-spool skin temperatures of an entrained-flow gasifier, as well as the internal temperature gradient of a fluidized bed combustor.

On the symmetry and crystal structures of Ba{sub 2}LaIrO{sub 6}

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

Fu, W.T., E-mail: w.fu@chem.leidenuniv.n; Goetz, R.J.; IJdo, D.J.W.

2010-02-15

Accurate profile analysis of X-ray diffraction data was carried out to settle recent dispute on the symmetry and crystal structures of the double perovskite Ba{sub 2}LaIrO{sub 6}. Even through careful comparison of the full-width at half-maximum values, we found no evidence for Ba{sub 2}LaIrO{sub 6} adopting either monoclinic (I2/m) or mixed rhombohedral (R3-bar) and monoclinic (I2/m) structures at room temperature, becoming triclinic (I1-bar) at below about 200 K. The correct space group is just R3-bar at temperatures between 82 and 653 K. Furthermore, the R3-bar->Fm3-barm phase transition does occur in Ba{sub 2}LaIrO{sub 6}, but the transition temperature is found tomore » be much higher than the reported value. - Graphical abstract: Observed (crosses) and calculated (continuous line) profiles of Ba{sub 2}LaIrO{sub 6} at some selected temperature showing the region containing the basic (222), (321) and (400) reflections. Tick marks below indicate the positions of the allowed Bragg's reflections.« less

Variability of Disk Emission in Pre-main-sequence and Related Stars. IV. Investigating the Structural Changes in the Inner Disk Region of MWC 480

NASA Astrophysics Data System (ADS)

Fernandes, Rachel B.; Long, Zachary C.; Pikhartova, Monika; Sitko, Michael L.; Grady, Carol A.; Russell, Ray W.; Luria, David M.; Tyler, Dakotah B.; Bayyari, Ammar; Danchi, William; Wisniewski, John P.

2018-04-01

We present five epochs of near-IR observations of the protoplanetary disk around MWC 480 (HD 31648) obtained with the SpeX spectrograph on NASA’s Infrared Telescope Facility between 2007 and 2013, inclusive. Using the measured line fluxes in the Pa β and Br γ lines, we found the mass accretion rates to be (1.26–2.30) × 10‑7 M ⊙ yr‑1 and (1.4–2.01) × 10‑7 M ⊙ yr‑1, respectively, but which varied by more than 50% from epoch to epoch. The spectral energy distribution reveals a variability of about 30% between 1.5 and 10 μm during this same period of time. We investigated the variability using of the continuum emission of the disk in using the Monte-Carlo Radiative Transfer Code HOCHUNK3D. We find that varying the height of the inner rim successfully produces a change in the NIR flux but lowers the far-IR emission to levels below all measured fluxes. Because the star exhibits bipolar flows, we utilized a structure that simulates an inner disk wind to model the variability in the near-IR, without producing flux levels in the far-IR that are inconsistent with existing data. For this object, variable near-IR emission due to such an outflow is more consistent with the data than changing the scale height of the inner rim of the disk.

Upper wide-angle viewing system for ITER

DOE PAGES

Lasnier, C. J.; McLean, A. G.; Gattuso, A.; ...

2016-08-15

The Upper Wide Angle Viewing System (UWAVS) will be installed on five upper ports of ITER. Here, this paper shows major requirements, gives an overview of the preliminary design with reasons for some design choices, examines self-emitted IR light from UWAVS optics and its effect on accuracy, and shows calculations of signal-to-noise ratios for the two-color temperature output as a function of integration time and divertor temperature. Accurate temperature output requires correction for vacuum window absorption vs. wavelength and for self-emitted IR, which requires good measurement of the temperature of the optical components. The anticipated signal-to-noise ratio using presently availablemore » IR cameras is adequate for the required 500 Hz frame rate.« less

Magnetocaloric effect in Sr2CrIrO6 double perovskite: Monte Carlo simulation

NASA Astrophysics Data System (ADS)

El Rhazouani, O.; Slassi, A.; Ziat, Y.; Benyoussef, A.

2017-05-01

Monte Carlo simulation (MCS) combined with the Metropolis algorithm has been performed to study the magnetocaloric effect (MCE) in the promising double perovskite (DP) Sr2CrIrO6 that has not so far been synthetized. This paper presents the global magneto-thermodynamic behavior of Sr2CrIrO6 compound in term of MCE and discusses the behavior in comparison to other DPs. Thermal dependence of the magnetization has been investigated for different values of reduced external magnetic field. Thermal magnetic entropy and its change have been obtained. The adiabatic temperature change and the relative cooling power have been established. Through the obtained results, Sr2CrIrO6 DP could have some potential applications for magnetic refrigeration over a wide temperature range above room temperature and at large magnetic fields.

Molecular hydrogen in the vicinity of NGC 7538 IRS 1 and IRS 2 - Temperature and ortho-to-para ratio

NASA Technical Reports Server (NTRS)

Hoban, Susan; Reuter, Dennis C.; Mumma, Michael J.; Storrs, Alex D.

1991-01-01

Near-infrared spectroscopic observations of the active star-forming region near NGC 7538 IRS 1 and IRS 2 were made. The relative intensities of the v = 1-0 Q(1), Q(3), and Q(5) lines of molecular hydrogen are used to calculate a rotational excitation temperature. Comparison of the measured intensity of the Q(2) transition relative to the intensity of Q(1) and Q(3) permitted the retrieval of the ratio of ortho-to-para hydrogen. It is found that an ortho-to-para ratio of between 1.6 and 2.35 is needed to explain the Q-branch line intensity ratios, depending on the excitation model used. This range in ortho-to-para ratios implies a range of molecular hydrogen formation temperature of approximately 105 K to 140 K.

Elastic, magnetic and electronic properties of iridium phosphide Ir 2P

DOE PAGES

Wang, Pei; Wang, Yonggang; Wang, Liping; ...

2016-02-24

Cubic (space group: Fm3¯m) iridium phosphide, Ir 2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir 2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B 0 = 306(6) GPa and its pressure derivative B 0'= 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first – principles calculations and three-dimensionally distributed [IrP 4] tetrahedron network. Indentation testing on a well–sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively lowmore » shear modulus of ~64 GPa from theoretical calculations suggests a complicated overall bonding in Ir 2P with metallic, ionic, and covalent characteristics. Additionally, a spin glass behavior is indicated by magnetic susceptibility measurements.« less

Infrared Imaging for Inquiry-Based Learning

ERIC Educational Resources Information Center

Xie, Charles; Hazzard, Edmund

2011-01-01

Based on detecting long-wavelength infrared (IR) radiation emitted by the subject, IR imaging shows temperature distribution instantaneously and heat flow dynamically. As a picture is worth a thousand words, an IR camera has great potential in teaching heat transfer, which is otherwise invisible. The idea of using IR imaging in teaching was first…

Models for Temperature and Composition in Uranus from Spitzer, Herschel and Ground-Based Infrared through Millimeter Observations

NASA Astrophysics Data System (ADS)

Orton, Glenn S.; Fletcher, Leigh N.; Feuchtgruber, Helmut; Lellouch, Emmanuel; Moreno, Raphel; Encrenaz, Therese; Hartogh, Paul; Jarchow, Christopher; Swinyard, Bruce; Cavalie, Thibault; Moses, Julianne; Burgdorf, Martin; Hammel, Heidi; Line, Michael; Mainzer, Amy K.; Hofstadter, Mark; Sandell, Goran H.; Dowell, C. Darren; Pantin, Eric; Fujiyoshi, Takuya

2014-11-01

Photometric and spectroscopic observations of Uranus in the thermal infrared were combined to create self-consistent models of its global-mean temperature profile and vertical distribution of gases. These were derived from a suite of observations from Spitzer and Herschel, together with ground-based observations from UKIRT, CSO, Gemini, VLT and Subaru. Observations of the collision-induced absorption and quadrupoles of H2 have constrained the temperature structure for pressures of nearly 2 bars down to 0.1 millibars. We coupled the vertical distribution of CH4 in the stratosphere of Uranus with models for the vertical mixing in such a way to be consistent with the mixing ratios of hydrocarbons. Spitzer and Herschel data constrain the abundances of CH3, CH4, C2H2, C2H6, C3H4, C4H2, H2O and CO2. The Spitzer IRS data, in concert with photochemical models, show that the homopause is at much higher atmospheric pressures than for the other outer planets, with the predominant trace constituents for pressures lower than 30 µbar being H2O and CO2. The ratio of the oxygen-bearing molecules is consistent with exogenic origins in KBOs or comets. At millimeter wavelengths, there is evidence that an additional opacity source is required besides the H2 collision-induced absorption and the NH3 absorption needed to match the microwave spectrum; this can reasonably (but not uniquely) be attributed to H2S. This model is of ‘programmatic’ interest because it serves as a standard calibration source; the cross-comparison of its spectrum with model spectra for Mars and Neptune shows consistency to within 3%. Near equinox, the IRS spectra at different longitudes showed rotationally variable stratospheric emission that is consistent with a temperature anomaly ≤10 K near ~0.1-0.2 mbar. Spatial variability of tropospheric temperatures observed in ground-based observations from 2006 to 2011 is generally consistent with Voyager infrared (IRIS) results.

Comparison of plasma pigment epithelium-derived factor (PEDF), retinol binding protein 4 (RBP-4), chitinase-3-like protein 1 (YKL-40) and brain-derived neurotrophic factor (BDNF) for the identification of insulin resistance.

PubMed

Toloza, F J K; Pérez-Matos, M C; Ricardo-Silgado, M L; Morales-Álvarez, M C; Mantilla-Rivas, J O; Pinzón-Cortés, J A; Pérez-Mayorga, M; Arévalo-García, M L; Tolosa-González, G; Mendivil, C O

2017-09-01

To evaluate and compare the association of four potential insulin resistance (IR) biomarkers (pigment-epithelium-derived factor [PEDF], retinol-binding-protein-4 [RBP-4], chitinase-3-like protein 1 [YKL-40] and brain-derived neurotrophic factor [BDNF]) with objective measures of IR. We studied 81 subjects with different metabolic profiles. All participants underwent a 5-point OGTT with calculation of multiple IR indexes. A subgroup of 21 participants additionally underwent a hyperinsulinemic-euglycemic clamp. IR was defined as belonging to the highest quartile of incremental area under the insulin curve (iAUCins), or to the lowest quartile of the insulin sensitivity index (ISI). PEDF was associated with adiposity variables. PEDF and RBP4 increased linearly across quartiles of iAUCins (for PEDF p-trend=0.029; for RBP-4 p-trend=0.053). YKL-40 and BDNF were not associated with any adiposity or IR variable. PEDF and RBP-4 levels identified individuals with IR by the iAUCins definition: A PEDF cutoff of 11.9ng/mL had 60% sensitivity and 68% specificity, while a RBP-4 cutoff of 71.6ng/mL had 70% sensitivity and 57% specificity. In multiple regression analyses simultaneously including clinical variables and the studied biomarkers, only BMI, PEDF and RBP-4 remained significant predictors of IR. Plasma PEDF and RBP4 identified IR in subjects with no prior diagnosis of diabetes. Copyright © 2017 Elsevier Inc. All rights reserved.

Infrared fiber optic sensor for measurements of nonuniform temperature distributions

NASA Astrophysics Data System (ADS)

Belotserkovsky, Edward; Drizlikh, S.; Zur, Albert; Bar-Or, O.; Katzir, Abraham

1992-04-01

Infrared (IR) fiber optic radiometry of thermal surfaces offers several advantages over refractive optics radiometry. It does not need a direct line of sight to the measured thermal surface and combines high capability of monitoring small areas with high efficiency. These advantages of IR fibers are important in the control of nonuniform temperature distributions, in which the temperature of closely situated points differs considerably and a high spatial resolution is necessary. The theoretical and experimental transforming functions of the sensor during scanning of an area with a nonuniform temperature distribution were obtained and their dependence on the spacial location of the fiber and type of temperature distribution were analyzed. Parameters such as accuracy and precision were determined. The results suggest that IR fiber radiometric thermometry may be useful in medical applications such as laser surgery, hyperthermia, and hypothermia.

The thermal decomposition of fine-grained micrometeorites, observations from mid-IR spectroscopy

NASA Astrophysics Data System (ADS)

Suttle, Martin David; Genge, Matthew J.; Folco, Luigi; Russell, Sara S.

2017-06-01

We analysed 44 fine-grained and scoriaceous micrometeorites. A bulk mid-IR spectrum (8-13 μm) for each grain was collected and the entire micrometeorite population classified into 5 spectral groups, based on the positions of their absorption bands. Corresponding carbonaceous Raman spectra, textural observations from SEM-BSE and bulk geochemical data via EMPA were collected to aid in the interpretation of mid-IR spectra. The 5 spectral groups identified correspond to progressive thermal decomposition. Unheated hydrated chondritic matrix, composed predominantly of phyllosilicates, exhibit smooth, asymmetric spectra with a peak at ∼10 μm. Thermal decomposition of sheet silicates evolves through dehydration, dehydroxylation, annealing and finally by the onset of partial melting. Both CI-like and CM-like micrometeorites are shown to pass through the same decomposition stages and produce similar mid-IR spectra. Using known temperature thresholds for each decomposition stage it is possible to assign a peak temperature range to a given micrometeorite. Since the temperature thresholds for decomposition reactions are defined by the phyllosilicate species and the cation composition and that these variables are markedly different between CM and CI classes, atmospheric entry should bias the dust flux to favour the survival of CI-like grains, whilst preferentially melting most CM-like dust. However, this hypothesis is inconsistent with empirical observations and instead requires that the source ratio of CI:CM dust is heavily skewed in favour of CM material. In addition, a small population of anomalous grains are identified whose carbonaceous and petrographic characteristics suggest in-space heating and dehydroxylation have occurred. These grains may therefore represent regolith micrometeorites derived from the surface of C-type asteroids. Since the spectroscopic signatures of dehydroxylates are distinctive, i.e. characterised by a reflectance peak at 9.0-9.5 μm, and since the surfaces of C-type asteroids are expected to be heated via impact gardening, we suggest that future spectroscopic investigations should attempt to identify dehydroxylate signatures in the reflectance spectra of young carbonaceous asteroid families.

Mice receiving infrared irradiation have a higher survival rate under forced swimming in cold.

PubMed

Tsai, Jui-Feng

2009-10-01

To explore the effect of infrared (IR) irradiation on the survival rates of mice under forced swimming in cold conditions. IR irradiation has been found to be beneficial for wound healing, tumor reduction, pain relief, and even against depression. However, whether the antidepressant effect of IR irradiation came from heat has remained unanswered. The goals of the study were originally aimed at using an animal model for depression to understand the relationship between the antidepressant effect of IR irradiation and hyperthermia as well as seasonality. Forty-four mice were housed in cages in a room subject to the outdoor temperature, and randomly assigned to the IR-treated group (n = 15), the heat-treated group (n = 14), and the control group (n = 15) during winter. The mice of the IR-treated group received whole-body IR irradiation for 60 min daily, while the heat-treated group received heat diffusion to reach the same temperature level. The control group received neither IR nor heat. All groups of mice underwent a forced swimming test weekly. Incidentally, two episodes of cold current occurred during the study period, and some mice died. The survival rates were compared pairwise against the control. The IR-treated group had a significantly reduced relative risk (p = 0.013) when compared with the control group, while the heat-treated group did not show any significant reduction (p = 0.087). There was no significant difference in body temperatures of the three groups before and after the irradiation. IR irradiation resulted in a significantly higher survival rate for mice that were concurrently subjected to cold and a forced swimming test. This result may be beyond the thermal effect.

CO2 as a hydrogen vector - transition metal diamine catalysts for selective HCOOH dehydrogenation.

PubMed

Fink, Cornel; Laurenczy, Gábor

2017-01-31

The homogeneous catalytic dehydrogenation of formic acid in aqueous solution provides an efficient in situ method for hydrogen production, under mild conditions, and at an adjustable rate. We synthesized a series of catalysts with the chemical formula [(Cp*)M(N-N')Cl] (M = Ir, Rh; Cp* = pentamethylcyclopentadienyl; N-N = bidentate chelating nitrogen donor ligands), which have been proven to be active in selective formic acid decomposition in aqueous media. The scope of the study was to examine the relationship between stability and activity of catalysts for formic acid dehydrogenation versus electronic and steric properties of selected ligands, following a bottom-up approach by increasing the complexity of the N,N'-ligands progressively. The highest turnover frequency, TOF = 3300 h -1 was observed with a Cp*Ir(iii) complex bearing 1,2-diaminocyclohexane as the N,N'-donor ligand. From the variable temperature studies, the activation energy of formic acid dehydrogenation has been determined, E a = 77.94 ± 3.2 kJ mol -1 . It was observed that the different steric and electronic properties of the bidentate nitrogen donor ligands alter the catalytic activity and stability of the Ir and Rh compounds profoundly.

Intravenous fluid temperature management by infrared thermometer.

PubMed

Lapostolle, Frédéric; Catineau, Jean; Le Toumelin, Philippe; Proust, Clément; Garrigue, Bruno; Galinski, Michel; Adnet, Frédéric

2006-03-01

The management of intravenous (IV) fluid temperature is a daily challenge in critical care, anesthesiology, and emergency medicine. Infusion of IV fluids at the right temperature partly influences clinical outcomes of critically ill patients. Nowadays, intravenous fluid temperature is poorly managed, as no suitable device is routinely available. Infrared (IR) thermometers have been recently developed for industrial, personal, or medical purposes. The aim of this study was to evaluate the accuracy of an IR thermometer in measuring temperature of warmed and cooled infusion fluids in fluid bags. This study compared temperatures simultaneously recorded by an infrared thermometer and a temperature sensor. Temperatures of warmed (41 degrees C) and cooled (4 degrees C) infusion fluids in fluid bags were recorded by 2 independent operators every minute until IV bags' temperature reached ambient temperature. The relation curve was established with 576 measures. Temperature measures performed with an IR thermometer were perfectly linear and perfectly correlated with the reference method (R(2) = 0.995, P < 10(-5)). Infrared thermometers are efficient to measure IV fluid bag temperature in the range of temperatures used in clinical practice. As these devices are easy to use and inexpensive, they could be largely used in critical care, anesthesiology, or emergency medicine.

Resilience of rice (Oryza spp.) pollen germination and tube growth to temperature stress.

PubMed

Coast, Onoriode; Murdoch, Alistair J; Ellis, Richard H; Hay, Fiona R; Jagadish, Krishna S V

2016-01-01

Resilience of rice cropping systems to potential global climate change will partly depend on the temperature tolerance of pollen germination (PG) and tube growth (PTG). Pollen germination of high temperature-susceptible Oryza glaberrima Steud. (cv. CG14) and Oryza sativa L. ssp. indica (cv. IR64) and high temperature-tolerant O. sativa ssp. aus (cv. N22), was assessed on a 5.6-45.4 °C temperature gradient system. Mean maximum PG was 85% at 27 °C with 1488 μm PTG at 25 °C. The hypothesis that in each pollen grain, the minimum temperature requirements (Tn ) and maximum temperature limits (Tx ) for germination operate independently was accepted by comparing multiplicative and subtractive probability models. The maximum temperature limit for PG in 50% of grains (Tx(50) ) was the lowest (29.8 °C) in IR64 compared with CG14 (34.3 °C) and N22 (35.6 °C). Standard deviation (sx ) of Tx was also low in IR64 (2.3 °C) suggesting that the mechanism of IR64's susceptibility to high temperatures may relate to PG. Optimum germination temperatures and thermal times for 1 mm PTG were not linked to tolerating high temperatures at anthesis. However, the parameters Tx(50) and sx in the germination model define new pragmatic criteria for successful and resilient PG, preferable to the more traditional cardinal (maximum and minimum) temperatures. © 2014 John Wiley & Sons Ltd.

Fabrication of IrSi(3)/p-Si Schottky diodes by a molecular beam epitaxy technique

NASA Technical Reports Server (NTRS)

Lin, T. L.; Iannelli, J. M.

1990-01-01

IrSi(3)/p-Si Schottky diodes have been fabricated by a molecular beam epitaxy technique at 630 C. Good surface morphology was observed for IrSi(3) layers grown at temperatures below 680 C, and an increasing tendency to form islands is observed in samples grown at higher temperatures. Good diode current-voltage characteristics were observed and Schottky barrier heights of 0.14-0.18 eV were determined by activation energy analysis and spectral response measurement.

Intercomparison of spectral irradiance measurements and provision of alternative radiation scheme for CCMs of middle atmosphere

NASA Astrophysics Data System (ADS)

Pagaran, Joseph; Weber, Mark; Burrows, John P.

The Sun's radiative output (total solar irradiance or TSI) determines the thermal structure of the Earth's atmosphere. Its variability is a strong function of wavelength, which drives the photochemistry and general circulation. Contributions to TSI variability from UV wavelengths below 400 nm, i.e. 0.227-day solar rotation or 0.1to be in the 40-60three decades of UV and about a decade of vis-IR observations. Significant progress in UV/vis-IR regions has been achieved with daily monitoring from SCIAMACHY aboard Envisat (ESA) in 2002 and by SIM aboard SORCE (NASA) about a year after. In this contribution, we intercompare SSI measurements from SCIAMACHY and SIM and RGB filters of SPM/VIRGO SoHO: same (a) day and (b) few 27-day time series of spectral measurements in both irradiance and integrated irradiance over selected wavelength intervals. Finally, we show how SSI measurements from GOME, SOLSTICE, in addition to SCIAMACHY and SIM, can be modeled together with solar proxies F10.7 cm, Mg II and sunspot index (PSI) to derive daily SSI variability in the period 1947-2008. The derived variabilities are currently being used as solar input to Bremen's 3D-CTM and are to be recommended as extended alternative to Berlin's FUBRaD radiation scheme. This proxy-based radiation scheme are compared with SATIRE, NRLSSI (or Lean et al.), SUSIM, SSAI (or DeLand et al), and SIP (or Solar2000) models. The use of realistic spectrally resolved solar input to CCMs is to better understand the effects of solar variability on chemistry and temperature in the middle atmosphere over several decades.

High Pressure and Temperature Core Formation as an Alternative to the "Late Veneer" Hypothesis

NASA Technical Reports Server (NTRS)

Righter, Kevin; Pando, K.; Humayun, M.; Danielson, L.

2011-01-01

The highly siderophile elements (HSE; Re, Au and the Platinum Group Elements - Pd Pt, Rh, Ru, Ir, Os) are commonly utilized to constrain accretion processes in terrestrial differentiated bodies due to their affinity for FeNi metal [1]. These eight elements exhibit highly siderophile behavior, but nonetheless have highly diverse metal-silicate partition coefficients [2]. Therefore the near chondritic relative concentrations of HSEs in the terrestrial and lunar mantles, as well as some other bodies, are attributed to late accretion rather than core formation [1]. Evaluation of competing theories, such as high pressure metal-silicate partitioning or magma ocean hypotheses has been hindered by a lack of relevant partitioning data for this group of eight elements. In particular, systematic studies isolating the effect of one variable (e.g. temperature or melt compositions) are lacking. Here we undertake new experiments on all eight elements, using Fe metal and FeO-bearing silicate melts at fixed pressure, but variable temperatures. These experiments, as well as some additional planned experiments should allow partition coefficients to be more accurately calculated or estimated at the PT conditions and compositions at which core formation is thought to have occurred.

On the Fast Evaluation Method of Temperature and Gas Mixing Ratio Weighting Functions for Remote Sensing of Planetary Atmospheres in Thermal IR and Microwave

NASA Technical Reports Server (NTRS)

Ustinov, E. A.

1999-01-01

Evaluation of weighting functions in the atmospheric remote sensing is usually the most computer-intensive part of the inversion algorithms. We present an analytic approach to computations of temperature and mixing ratio weighting functions that is based on our previous results but the resulting expressions use the intermediate variables that are generated in computations of observable radiances themselves. Upwelling radiances at the given level in the atmosphere and atmospheric transmittances from space to the given level are combined with local values of the total absorption coefficient and its components due to absorption of atmospheric constituents under study. This makes it possible to evaluate the temperature and mixing ratio weighting functions in parallel with evaluation of radiances. This substantially decreases the computer time required for evaluation of weighting functions. Implications for the nadir and limb viewing geometries are discussed.

IR Variability of Eta Carinae

NASA Astrophysics Data System (ADS)

Smith, Nathan

2007-02-01

Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron. In addition, η Car shows long term changes as it is still recovering from its giant 19th century outburst. Both types of variability are directly linked to the current mass-loss rate and dust formation in its wind. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and trace dust formation episodes. This will provide a direct measurement of the mass ejected. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with GNIRS will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula.

Thermal Image Sensing Model for Robotic Planning and Search

PubMed Central

Castro Jiménez, Lídice E.; Martínez-García, Edgar A.

2016-01-01

This work presents a search planning system for a rolling robot to find a source of infra-red (IR) radiation at an unknown location. Heat emissions are observed by a low-cost home-made IR passive visual sensor. The sensor capability for detection of radiation spectra was experimentally characterized. The sensor data were modeled by an exponential model to estimate the distance as a function of the IR image’s intensity, and, a polynomial model to estimate temperature as a function of IR intensities. Both theoretical models are combined to deduce a subtle nonlinear exact solution via distance-temperature. A planning system obtains feed back from the IR camera (position, intensity, and temperature) to lead the robot to find the heat source. The planner is a system of nonlinear equations recursively solved by a Newton-based approach to estimate the IR-source in global coordinates. The planning system assists an autonomous navigation control in order to reach the goal and avoid collisions. Trigonometric partial differential equations were established to control the robot’s course towards the heat emission. A sine function produces attractive accelerations toward the IR source. A cosine function produces repulsive accelerations against the obstacles observed by an RGB-D sensor. Simulations and real experiments of complex indoor are presented to illustrate the convenience and efficacy of the proposed approach. PMID:27509510

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals.

PubMed

Diroll, Benjamin T; Schramke, Katelyn S; Guo, Peijun; Kortshagen, Uwe R; Schaller, Richard D

2017-10-11

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows for selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a subpicosecond change of the dielectric function, resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27%, and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates subpicosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting the modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

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

Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

DOE PAGES

Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun; ...

2017-09-11

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

High-Temperature Oxidation Behavior of Iridium-Rhenium Alloys

NASA Technical Reports Server (NTRS)

Reed, Brian D.

1995-01-01

The life-limiting mechanism for radiation-cooled rockets made from iridium-coated rhenium (Ir/Re) is the diffusion of Re into the Ir layer and the subsequent oxidation of the resulting Ir-Re alloy from the inner surface. In a previous study, a life model for Ir/Re rockets was developed. It incorporated Ir-Re diffusion and oxidation data to predict chamber lifetimes as a function of temperature and oxygen partial pressure. Oxidation testing at 1540 deg C suggested that a 20-wt percent Re concentration at the inner wall surface should be established as the failure criterion. The present study was performed to better define Ir-oxidation behavior as a function of Re concentration and to supplement the data base for the life model. Samples ranging from pure Ir to Ir-40 wt percent Re (Ir-40Re) were tested at 1500 deg C, in two different oxygen environments. There were indications that the oxidation rate of the Ir-Re alloy increased significantly when it went from a single-phase solid solution to a two-phase mixture, as was suggested in previous work. However, because of testing anomalies in this study, there were not enough dependable oxidation data to definitively raise the Ir/Re rocket failure criterion from 20-wt percent Re to a Re concentration corresponding to entry into the two-phase region.

Insulation Resistance and Leakage Currents in Low-Voltage Ceramic Capacitors with Cracks

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2014-01-01

Measurement of insulation resistance (IR) in multilayer ceramic capacitors (MLCCs) is considered a screening technique that ensures the dielectric is defect-free. This work analyzes the effectiveness of this technique for revealing cracks in ceramic capacitors. It is shown that absorption currents prevail over the intrinsic leakage currents during standard IR measurements at room temperature. Absorption currents, and consequently IR, have a weak temperature dependence, increase linearly with voltage (before saturation), and are not sensitive to the presence of mechanical defects. In contrary, intrinsic leakage currents increase super-linearly with voltage and exponentially with temperature (activation energy is in the range from 0.6 eV to 1.1 eV). Leakage currents associated with the presence of cracks have a weaker dependence on temperature and voltage compared to the intrinsic leakage currents. For this reason, intrinsic leakage currents prevail at high temperatures and voltages, thus masking the presence of defects.

Insulation Resistance and Leakage Currents in Low-Voltage Ceramic Capacitors with Cracks

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2016-01-01

Measurement of insulation resistance (IR) in multilayer ceramic capacitors (MLCCs) is considered a screening technique that ensures the dielectric is defect-free. This work analyzes the effectiveness of this technique for revealing cracks in ceramic capacitors. It is shown that absorption currents prevail over the intrinsic leakage currents during standard IR measurements at room temperature. Absorption currents, and consequently IR, have a weak temperature dependence, increase linearly with voltage (before saturation), and are not sensitive to the presence of mechanical defects. In contrary, intrinsic leakage currents increase super-linearly with voltage and exponentially with temperature (activation energy is in the range from 0.6 eV to 1.1 eV). Leakage currents associated with the presence of cracks have a weaker dependence on temperature and voltage compared to the intrinsic leakage currents. For this reason, intrinsic leakage currents prevail at high temperatures and voltages, thus masking the presence of defects.

Vibrational and thermodynamic properties of Ar, N2, O2, H2 and CO adsorbed and condensed into (H,Na)-Y zeolite cages as studied by variable temperature IR spectroscopy.

PubMed

Gribov, Evgueni N; Cocina, Donato; Spoto, Giuseppe; Bordiga, Silvia; Ricchiardi, Gabriele; Zecchina, Adriano

2006-03-14

The adsorption of Ar, H2, O2, N2 and CO on (H,Na)-Y zeolite (Si/Al = 2.9, H+/Na+ approximately 5) has been studied at variable-temperature (90-20 K) and sub-atmospheric pressure (0-40 mbar) by FTIR spectroscopy. Unprecedented filling conditions of the zeolite cavities were attained, which allowed the investigation of very weakly adsorbed species and of condensed, liquid-like or solid-like, phases. Two pressure regimes were singled out, characterized by: (i) specific interaction at low pressure of the probe molecules (P) with the internal Brønsted and Lewis sites, and (ii) multilayer adsorption at higher pressure. In the case of CO the perturbation of the protonic sites located inside the sodalite cages was also observed. As the molecule is too large to penetrate the sodalite cage, the perturbation is thought to involve a proton jump tunneling mechanism. The adsorption energy for the (HF)OH...P (P = Ar, H2, O2, N2 and CO) specific interaction involving the high frequency Brønsted acid sites exposed in the supercages was derived following the VTIR (variable temperature infrared spectroscopy) method described by E. Garrone and C. Otero Areán (Chem. Soc. Rev., 2005, 34, 846).

Stabilizing Ir(001) Epitaxy on Yttria-Stabilized Zirconia Using a Thin Ir Seed Layer Grown by Pulsed Laser Deposition

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

Fan, Lisha; Jacobs, Christopher B.; Rouleau, Christopher M.

In this paper, we demonstrate the reproducible epitaxial growth of 100 nm thick Ir(001) films on a heteroepitaxial stack consisting of 5 nm Ir and 100 nm yttria-stabilized zirconia (YSZ) grown on Si(001) substrates. It is shown that a 5 nm thick Ir layer grown by pulsed laser deposition in the same chamber as the YSZ film without breaking the vacuum is the key to stabilizing Ir(001) epitaxial growth. Growth of the Ir seed layer with pure (001) orientation occurs only in a narrow growth temperature window from 550 to 750 °C, and the fraction of Ir(111) increases at substratemore » temperatures outside of this window. The Ir seed layer prevents exposure of the YSZ film to air during sample transfer and enables highly reproducible Ir(001) heteroepitaxy on YSZ buffered Si(001). In contrast, if Ir is grown directly on a bare YSZ layer that was exposed to ambient conditions, the films are prone to change orientation to (111). These results reveal that preserving the chemical and structural purity of the YSZ surface is imperative for achieving Ir(001) epitaxy. The narrow range of the mosaic spread values from eight experiments demonstrates the high yield and high reproducibility of Ir(001) heteroepitaxy by this approach. Lastly, the improved Ir(001) epitaxial growth method is of great significance for integrating a variety of technologically important materials such as diamond, graphene, and functional oxides on a Si platform.« less

Stabilizing Ir(001) Epitaxy on Yttria-Stabilized Zirconia Using a Thin Ir Seed Layer Grown by Pulsed Laser Deposition

DOE PAGES

Fan, Lisha; Jacobs, Christopher B.; Rouleau, Christopher M.; ...

2016-11-18

In this paper, we demonstrate the reproducible epitaxial growth of 100 nm thick Ir(001) films on a heteroepitaxial stack consisting of 5 nm Ir and 100 nm yttria-stabilized zirconia (YSZ) grown on Si(001) substrates. It is shown that a 5 nm thick Ir layer grown by pulsed laser deposition in the same chamber as the YSZ film without breaking the vacuum is the key to stabilizing Ir(001) epitaxial growth. Growth of the Ir seed layer with pure (001) orientation occurs only in a narrow growth temperature window from 550 to 750 °C, and the fraction of Ir(111) increases at substratemore » temperatures outside of this window. The Ir seed layer prevents exposure of the YSZ film to air during sample transfer and enables highly reproducible Ir(001) heteroepitaxy on YSZ buffered Si(001). In contrast, if Ir is grown directly on a bare YSZ layer that was exposed to ambient conditions, the films are prone to change orientation to (111). These results reveal that preserving the chemical and structural purity of the YSZ surface is imperative for achieving Ir(001) epitaxy. The narrow range of the mosaic spread values from eight experiments demonstrates the high yield and high reproducibility of Ir(001) heteroepitaxy by this approach. Lastly, the improved Ir(001) epitaxial growth method is of great significance for integrating a variety of technologically important materials such as diamond, graphene, and functional oxides on a Si platform.« less

Thermal stability of chemically bonded phases on silica gel by photoacoustic FT-IR spectroscopy

NASA Astrophysics Data System (ADS)

Kierys, A.; Pasieczna, S.; Ryczkowski, J.; Goworek, J.

2006-11-01

The temperature resistance of chemically bonded phases on commercial silica gel, LiChrosorb RP 2, RP 8, RP 18 and unmodified Si 60 were tested at different temperatures by photoacoustic FT-IR spectroscopy. The surface characteristics and possible degradation of hydrocarbon phase at higher temperatures were investigated by means of FT-IR/PAS technique. For a series of investigated samples heated up to 423 K, the FT-IR/PAS spectra are similar to those for initial silica samples. The most characteristic band for alkyl modified silica gel, i.e., RP 2, RP 8, and RP 18 was observed between 3200 cm-1 to 2800 cm-1 corresponding to various hydrocarbon species. The bands at 3745 cm-1, 3650 cm-1, and 3430 cm-1 observed in the photoacoustic FT-IR spectra may be ascribed to isolated silanol groups (Si-OH), geminal groups (Si-(OH)2) and hydrogen-bonded Si-OH groups, respectively. For all samples the intensity of the broad band in the region 3800 cm-1 to 3200 cm-1 decreases with the increasing temperature. The additional peak at 3745 cm-1 for chemically bonded long hydrocarbon chain, i.e., C18 and C8 after thermal treatment at 573 K is observed.

Validity of infrared tympanic temperature for the evaluation of heat strain while wearing impermeable protective clothing in hot environments.

PubMed

Lee, Joo-Young; Nakao, Kouhei; Takahashi, Naoki; Son, Su-Young; Bakri, Ilham; Tochihara, Yutaka

2011-01-01

The purpose of this study was to investigate the validity of infrared tympanic temperature (IR T(ty)) as a thermal index to evaluate the heat strain of workers in hot environments, in comparison with rectal temperatures at various depths (T(re-4, -8, and -16) for 4, 8 and 16 cm from the anal sphincter). Eight males underwent twelve experimental conditions: two activities (rest and exercise) × three clothing levels [Control, HDPE (high-density polyethylene coverall) and PVC (polyvinyl chloride coverall) condition] × two air temperatures (25 and 32℃ with 50%RH). The results showed that 1) in the conditions with most heat strain (HDPE or PVC condition at 32℃), IR T(ty) was equal to or even higher than T(re); 2) during exercise, physiological strain index (PSI) using IR T(ty) did not underestimate PSI-values using T(re-16), and overestimated those PSI-values from T(re-16) in HDPE and PVC conditions at 32℃; 3) during exercise, the relationships between IR T(ty) and heart and total sweat rate were stronger than those between T(re-16) and heart and total sweat rate. These results indicated that IR T(ty) is valid as a thermal index to evaluate the heat strain of workers wearing impermeable protective coveralls in hot environments. However, the application of IR T(ty) is limited only for strenuous works wearing encapsulated personal protective clothing with a hood in heat.

Exceptionally long-lived light-emitting electrochemical cells: multiple intra-cation π-stacking interactions in [Ir(C^N)2(N^N)][PF6] emitters† †Electronic supplementary information (ESI) available: Experimental details. Fig. S1–S10: additional structural and NMR spectroscopic figures; voltage vs. time plots for LEC devices and electroluminescence spectra. CCDC 1019226–1019229. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03942d

PubMed Central

Bünzli, Andreas M.; Constable, Edwin C.; Prescimone, Alessandro; Zampese, Jennifer A.; Longo, Giulia; Gil-Escrig, Lidón; Pertegás, Antonio; Ortí, Enrique

2015-01-01

A series of cyclometalated iridium(iii) complexes [Ir(C^N)2(N^N)][PF6] (N^N = 2,2′-bipyridine (1), 6-phenyl-2,2′-bipyridine (2), 4,4′-di-tert-butyl-2,2′-bipyridine (3), 4,4′-di-tert-butyl-6-phenyl-2,2′-bipyridine (4); HC^N = 2-(3-phenyl)phenylpyridine (HPhppy) or 2-(3,5-diphenyl)phenylpyridine (HPh2ppy)) are reported. They have been synthesized using solvento precursors so as to avoid the use of chlorido-dimer intermediates, chloride ion contaminant being detrimental to the performance of [Ir(C^N)2(N^N)][PF6] emitters in light-electrochemical cell (LEC) devices. Single crystal structure determinations and variable temperature solution 1H NMR spectroscopic data confirm that the pendant phenyl domains engage in multiple face-to-face π-interactions within the coordination sphere of the iridium(iii) centre. The series of [Ir(Phppy)2(N^N)]+ and [Ir(Ph2ppy)2(N^N)]+ complexes investigated include those with and without intra-cation face-to-face π-stacking. All the complexes display excellent luminescent properties, in particular when employed in thin solid films. The most important observation is that all the LECs using the [Ir(Phppy)2(N^N)]+ and [Ir(Ph2ppy)2(N^N)]+ emitters (i.e. with and without intra-cation π-stacking interactions) exhibit very stable luminance outputs over time, even when driven at elevated current densities. The most stable LEC had an extrapolated lifetime of more than 2500 hours under accelerated testing conditions. PMID:29142683

Multifrequency observations of symbiotic stars

NASA Technical Reports Server (NTRS)

Kenyon, Scott J.

1988-01-01

The discovery of symbiotic stars is described, and the results of multifrequency observations made during the past two decades are presented. Observational data identify symbiotic stars as long-period binary systems that can be divided into two basic physical classes: detached symbiotics containing a red giant (or a Mira variable), and semidetached symbiotics containing a lobe-filling red giant and a solar-type main sequence star. Three components are typically observed: (1) the cool giant component with an effective temperature of 2500-4000 K, which can be divided by the IR spectral classification into normal M giants (S-types) and heavily reddened Mira variables (D-types); (2) the hot companion displaying a bright blue continuum at UV wavelengths, which is sometimes also an X-ray source; and (3) a gaseous nebula enveloping the binary.

Nanosegregated bimetallic oxide anode catalyst for proton exchange membrane electrolyzer

DOEpatents

Danilovic, Nemanja; Kang, Yijin; Markovic, Nenad; Stamenkovic, Vojislav; Myers, Deborah J.; Subbaraman, Ram

2016-08-23

A surface segregated bimetallic composition of the formula Ru.sub.1-xIr.sub.x wherein 0.1.ltoreq.x.ltoreq.0.75, wherein a surface of the material has an Ir concentration that is greater than an Ir concentration of the material as a whole is provided. The surface segregated material may be produced by a method including heating a bimetallic composition of the formula Ru.sub.1-xIr.sub.x, wherein 0.1.ltoreq.x.ltoreq.0.75, at a first temperature in a reducing environment, and heating the composition at a second temperature in an oxidizing environment. The surface segregated material may be utilized in electrochemical devices.

Diffusion mechanisms in chemical vapor-deposited iridium coated on chemical vapor-deposited rhenium

NASA Technical Reports Server (NTRS)

Hamilton, J. C.; Yang, N. Y. C.; Clift, W. M.; Boehme, D. R.; Mccarty, K. F.; Franklin, J. E.

1992-01-01

Radiation-cooled rocket thruster chambers have been developed which use CVD Re coated with CVD Ir on the interior surface that is exposed to hot combustion gases. The Ir serves as an oxidation barrier which protects the structural integrity-maintaining Re at elevated temperatures. The diffusion kinetics of CVD materials at elevated temperatures is presently studied with a view to the prediction and extension of these thrusters' performance limits. Line scans for Ir and Re were fit on the basis of a diffusion model, in order to extract relevant diffusion constants; the fastest diffusion process is grain-boundary diffusion, where Re diffuses down grain boundaries in the Ir overlayer.

Seasonal Variability of Saturn's Tropospheric Temperatures, Winds and Para-H2 from Cassini Far-IR Spectroscopy

NASA Technical Reports Server (NTRS)

Fletcher, Leigh N.; Irwin, P. G. J; Achterberg, R. K.; Orton, G. S.; Flasar, F. M.

2015-01-01

Far-IR 16-1000 micrometer spectra of Saturn's hydrogen-helium continuum measured by Cassini's Composite Infrared Spectrometer (CIRS) are inverted to construct a near-continuous record of upper tropospheric (70-700 mbar) temperatures and para-H2 fraction as a function of latitude, pressure and time for a third of a saturnian year (2004-2014, from northern winter to northern spring). The thermal field reveals evidence of reversing summertime asymmetries superimposed onto the belt/zone structure. The temperature structure is almost symmetric about the equator by 2014, with seasonal lag times that increase with depth and are qualitatively consistent with radiative climate models. Localised heating of the tropospheric hazes (100-250 mbar) create a distinct perturbation to the temperature profile that shifts in magnitude and location, declining in the autumn hemisphere and growing in the spring. Changes in the para-H2 (f(sub p)) distribution are subtle, with a 0.02-0.03 rise over the spring hemisphere (200-500 mbar) perturbed by (i) low-f(sub p) air advected by both the springtime storm of 2010 and equatorial upwelling; and (ii) subsidence of high-f(sub p) air at northern high latitudes, responsible for a developing north-south asymmetry in f(sub p). Conversely, the shifting asymmetry in the para-H2 disequilibrium primarily reflects the changing temperature structure (and hence the equilibrium distribution of f(sub p)), rather than actual changes in f(sub p) induced by chemical conversion or transport. CIRS results interpolated to the same point in the seasonal cycle as re-analysed Voyager-1 observations (early northern spring) show qualitative consistency from year to year (i.e., the same tropospheric asymmetries in temperature and f(sub p)), with the exception of the tropical tropopause near the equatorial zones and belts, where downward propagation of a cool temperature anomaly associated with Saturn's stratospheric oscillation could potentially perturb tropopause temperatures, para-H2 and winds. Quantitative differences between the Cassini and Voyager epochs suggest that the oscillation is not in phase with the seasonal cycle at these tropospheric depths (i.e., it should be described as quasi-periodic rather than 'semi annual'). Variability in the zonal wind field derived from latitudinal thermal gradients is small (less than 10 m/s per scale height near the tropopause) and mostly affects the broad retrograde jets, with the notable exception of large variability on the northern flank of the equatorial jet. The meridional potential vorticity (PV) gradient, and hence the 'staircase of PV' associated with spatial variations in the vigour of vertical mixing, has varied over the course of the mission but maintained its overall shape. PV gradients in latitude and altitude are used to estimate the atmospheric refractive index for the propagation of stationary planetary (Rossby) waves, predicting that such wave activity would be confined to regions of real refractivity (tropical regions plus bands at 35-45 in both hemispheres). The penetration depth of these regions into the upper troposphere is temporally variable (potentially associated with stratification changes), whereas the latitudinal structure is largely unchanged over time (associated with the zonal jet system).

Measurement and thermal modeling of sapphire substrate temperature at III-Nitride MOVPE conditions

DOE PAGES

Creighton, J. Randall; Coltrin, Michael E.; Figiel, Jeffrey J.

2017-04-01

Here, growth rates and alloy composition of AlGaN grown by MOVPE is often very temperature dependent due to the presence of gas-phase parasitic chemical processes. These processes make wafer temperature measurement highly important, but in fact such measurements are very difficult because of substrate transparency in the near- IR (~900 nm) where conventional pyrometers detect radiation. The transparency problem can be solved by using a mid-IR pyrometer operating at a wavelength (~7500 nm) where sapphire is opaque. We employ a mid- IR pyrometer to measure the sapphire wafer temperature and simultaneously a near-IR pyrometer to measure wafer pocket temperature, whilemore » varying reactor pressure in both a N 2 and H 2 ambient. Near 1300 °C, as the reactor pressure is lowered from 300 Torr to 10 Torr the wafer temperature drops dramatically, and the ΔT between the pocket and wafer increases from ~20 °C to ~250 °C. Without the mid-IR pyrometer the large wafer temperature change with pressure would not have been noted. In order to explain this behavior we have developed a quasi-2D thermal model that includes a proper accounting of the pressure-dependent thermal contact resistance, and also accounts for sapphire optical transmission. The model and experimental results demonstrate that at most growth conditions the majority of the heat is transported from the wafer pocket to the wafer via gas conduction, in the free molecular flow limit. In this limit gas conductivity is independent of gap size but first order in pressure, and can quantitatively explain results from 20 to 300 Torr. Further analysis yields a measure of the thermal accommodation coefficients; α(H 2) =0.23, α(N 2) =0.50, which are in the range typically measured.« less

Calibration and Evaluation of Ultrasound Thermography using Infrared Imaging

PubMed Central

Hsiao, Yi-Sing; Deng, Cheri X.

2015-01-01

Real-time monitoring of the spatiotemporal evolution of tissue temperature is important to ensure safe and effective treatment in thermal therapies including hyperthermia and thermal ablation. Ultrasound thermography has been proposed as a non-invasive technique for temperature measurement, and accurate calibration of the temperature-dependent ultrasound signal changes against temperature is required. Here we report a method that uses infrared (IR) thermography for calibration and validation of ultrasound thermography. Using phantoms and cardiac tissue specimens subjected to high-intensity focused ultrasound (HIFU) heating, we simultaneously acquired ultrasound and IR imaging data from the same surface plane of a sample. The commonly used echo time shift-based method was chosen to compute ultrasound thermometry. We first correlated the ultrasound echo time shifts with IR-measured temperatures for material-dependent calibration and found that the calibration coefficient was positive for fat-mimicking phantom (1.49 ± 0.27) but negative for tissue-mimicking phantom (− 0.59 ± 0.08) and cardiac tissue (− 0.69 ± 0.18 °C-mm/ns). We then obtained the estimation error of the ultrasound thermometry by comparing against the IR measured temperature and revealed that the error increased with decreased size of the heated region. Consistent with previous findings, the echo time shifts were no longer linearly dependent on temperature beyond 45 – 50 °C in cardiac tissues. Unlike previous studies where thermocouples or water-bath techniques were used to evaluate the performance of ultrasound thermography, our results show that high resolution IR thermography provides a useful tool that can be applied to evaluate and understand the limitations of ultrasound thermography methods. PMID:26547634

Fast Variability and Millimeter/IR Flares in GRMHD Models of Sgr A* from Strong-field Gravitational Lensing

NASA Astrophysics Data System (ADS)

Chan, Chi-kwan; Psaltis, Dimitrios; Özel, Feryal; Medeiros, Lia; Marrone, Daniel; Saḑowski, Aleksander; Narayan, Ramesh

2015-10-01

We explore the variability properties of long, high-cadence general relativistic magnetohydrodynamic (GRMHD) simulations across the electromagnetic spectrum using an efficient, GPU-based radiative transfer algorithm. We focus on both standard and normal evolution (SANE) and magnetically arrested disk (MAD) simulations with parameters that successfully reproduce the time-averaged spectral properties of Sgr A* and the size of its image at 1.3 mm. We find that the SANE models produce short-timescale variability with amplitudes and power spectra that closely resemble those inferred observationally. In contrast, MAD models generate only slow variability at lower flux levels. Neither set of models shows any X-ray flares, which most likely indicates that additional physics, such as particle acceleration mechanisms, need to be incorporated into the GRMHD simulations to account for them. The SANE models show strong, short-lived millimeter/infrared (IR) flares, with short (≲1 hr) time lags between the millimeter and IR wavelengths, that arise from the combination of short-lived magnetic flux tubes and strong-field gravitational lensing near the horizon. Such events provide a natural explanation for the observed IR flares with no X-ray counterparts.

FAST VARIABILITY AND MILLIMETER/IR FLARES IN GRMHD MODELS OF Sgr A* FROM STRONG-FIELD GRAVITATIONAL LENSING

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

Chan, Chi-kwan; Psaltis, Dimitrios; Özel, Feryal

2015-10-20

We explore the variability properties of long, high-cadence general relativistic magnetohydrodynamic (GRMHD) simulations across the electromagnetic spectrum using an efficient, GPU-based radiative transfer algorithm. We focus on both standard and normal evolution (SANE) and magnetically arrested disk (MAD) simulations with parameters that successfully reproduce the time-averaged spectral properties of Sgr A* and the size of its image at 1.3 mm. We find that the SANE models produce short-timescale variability with amplitudes and power spectra that closely resemble those inferred observationally. In contrast, MAD models generate only slow variability at lower flux levels. Neither set of models shows any X-ray flares,more » which most likely indicates that additional physics, such as particle acceleration mechanisms, need to be incorporated into the GRMHD simulations to account for them. The SANE models show strong, short-lived millimeter/infrared (IR) flares, with short (≲1 hr) time lags between the millimeter and IR wavelengths, that arise from the combination of short-lived magnetic flux tubes and strong-field gravitational lensing near the horizon. Such events provide a natural explanation for the observed IR flares with no X-ray counterparts.« less

Water of Hydration Dynamics in Minerals Gypsum and Bassanite: Ultrafast 2D IR Spectroscopy of Rocks.

PubMed

Yan, Chang; Nishida, Jun; Yuan, Rongfeng; Fayer, Michael D

2016-08-03

Water of hydration plays an important role in minerals, determining their crystal structures and physical properties. Here ultrafast nonlinear infrared (IR) techniques, two-dimensional infrared (2D IR) and polarization selective pump-probe (PSPP) spectroscopies, were used to measure the dynamics and disorder of water of hydration in two minerals, gypsum (CaSO4·2H2O) and bassanite (CaSO4·0.5H2O). 2D IR spectra revealed that water arrangement in freshly precipitated gypsum contained a small amount of inhomogeneity. Following annealing at 348 K, water molecules became highly ordered; the 2D IR spectrum became homogeneously broadened (motional narrowed). PSPP measurements observed only inertial orientational relaxation. In contrast, water in bassanite's tubular channels is dynamically disordered. 2D IR spectra showed a significant amount of inhomogeneous broadening caused by a range of water configurations. At 298 K, water dynamics cause spectral diffusion that sampled a portion of the inhomogeneous line width on the time scale of ∼30 ps, while the rest of inhomogeneity is static on the time scale of the measurements. At higher temperature, the dynamics become faster. Spectral diffusion accelerates, and a portion of the lower temperature spectral diffusion became motionally narrowed. At sufficiently high temperature, all of the dynamics that produced spectral diffusion at lower temperatures became motionally narrowed, and only homogeneous broadening and static inhomogeneity were observed. Water angular motions in bassanite exhibit temperature-dependent diffusive orientational relaxation in a restricted cone of angles. The experiments were made possible by eliminating the vast amount of scattered light produced by the granulated powder samples using phase cycling methods.

Synthesis, Structure, and Complex Magnetism of MIr 2In 8 (M = Eu, Sr)

DOE PAGES

Calta, Nicholas P.; L. Bud’ko, Sergey; Rodriguez, Alexandra P.; ...

2016-03-07

In this paper, we report the synthesis, crystal structure, and physical properties of two new polar intermetallic compounds, EuIr 2In 8 and SrIr 2In 8. Both were synthesized in good yield using In metal as a reactive flux medium, enabling the growth of large crystals for physical property measurements. They crystallize in the orthorhombic space group Pbam with the CeFe 2Al 8 structure type, which is sometimes also referred to as the CaCo 2Al 8 structure type. The two analogues have unit cell parameters of a = 13.847(3) Å, b = 16.118(3) Å, and c = 4.3885(9) Å for Mmore » = Eu and a = 13.847(3) Å, b = 16.113(3) Å, and c = 4.3962(9) Å for M = Sr at room temperature. SrIr 2In 8 is a diamagnetic metal with no local magnetic moments on either the Sr or Ir sites, and the diamagnetic contribution from core electrons overwhelms the expected Pauli paramagnetism normally seen in intermetallic compounds. Magnetism in EuIr 2In 8 is dominated by the local Eu moments, which order antiferromagnetically at 5 K in low applied fields. Increasing the field strength depresses the magnetic ordering temperature and also induces a spin reorientation at lower temperature, indicating complex competing magnetic interactions. Finally, low-temperature heat capacity measurements show a significant enhancement of the Sommerfeld coefficient in EuIr 2In 8 relative to that in SrIr 2In 8, with estimated values of γ = 118(3) and 18.0(2) mJ mol –1 K –2, respectively.« less

High operating temperature IR-modules with reduced pitch for SWaP sensitive applications

NASA Astrophysics Data System (ADS)

Breiter, R.; Wendler, J.; Lutz, H.; Rutzinger, S.; Ihle, T.; Ziegler, J.; Rühlich, I.

2011-06-01

Low size, weight and power (SWaP) are the most critical requirements for portable thermal imagers like weapon sights or handheld observations devices. On the other hand due to current asymmetrical conflicts there are high requirements for the e/o performance of these devices providing the ability to distinguish between combatants and non-combatants in adequate ranges. Despite of all the success with uncooled technology, such requirements usually still require cooled detectors. AIM has developed a family of thermal weapon sights called HuntIR and RangIR based on high performance cooled IR-modules which are used e.g. in the infantryman of the future program of the German army (IdZ). The specific capability of these devices is a high ID range >1500m for tank targets being suitable in use as thermal sights for .50 cal rifles like the G82, targeting units for the 40mm AGL or for night observation. While such ranges sound far beyond the operational needs in urban operations, the a.m. specific needs of asymmetric warfare require sometimes even more range performance. High operating temperature (HOT) is introduced in the AIM MCT 640x512/15μm MWIR or LWIR modules for further reduction of cooler power consumption, shorter cooldown times and higher MTTF. As a key component to keep performance while further reducing SWaP AIM is developing a new cooled MCT IR-module with reduced pitch of 12 μm operating at a temperature >120 K. The module will provide full TV format with 640x480 elements sensitive in the MWIR spectral band. The paper will show recent results of AIM IR-modules with high operating temperature and the impact of design regarding the IR-module itself and thermal sights making use of it.

Sensitivity of the Yo-Yo Intermittent Recovery Test and cardiac autonomic responses to training in futsal players.

PubMed

de Freitas, Victor H; Pereira, Lucas A; de Souza, Eberton A; Leicht, Anthony S; Bertollo, Maurizio; Nakamura, Fábio Y

2015-07-01

This study examined the sensitivity of maximal (Yo-Yo Intermittent Recovery [IR] 1 and 2) and submaximal (5'-5') tests to identify training adaptations in futsal players along with the suitability of heart-rate (HR) and HR-variability (HRV) measures to identify these adaptations. Eleven male professional futsal players were assessed before (pretraining) and after (posttraining) a 5-wk period. Assessments included 5'-5' and Yo-Yo IR1 and IR2 performances and HR and HRV at rest and during the IR and 5'-5' tests. Magnitude-based-inference analyses examined the differences between pre- and posttraining, while relationships between changes in variables were determined via correlation. Posttraining, Yo-Yo IR1 performance likely increased while Yo-Yo IR2 performance almost certainly increased. Submaximal HR during the Yo-Yo IR1 and Yo-Yo IR2 almost certainly and likely, respectively, decreased with training. HR during the 5'-5' was very likely decreased, while HRV at rest and during the 5'-5' was likely increased after training. Changes in both Yo-Yo IR performances were negatively correlated with changes in HR during the Yo-Yo IR1 test and positively correlated with the change in HRV during the 5'-5'. The current study has identified the Yo-Yo IR2 as more responsive for monitoring training-induced changes of futsal players than the Yo-Yo IR1. Changes in submaximal HR during the Yo-Yo IR and HRV during the 5'-5' were highly sensitive to changes in maximal performance and are recommended for monitoring training. The 5'-5' was recommended as a time-efficient method to assess training adaptations for futsal players.

IR thermocycler for centrifugal microfluidic platform with direct on-disk wireless temperature measurement system

NASA Astrophysics Data System (ADS)

Burger, J.; Gross, A.; Mark, D.; Roth, G.; von Stetten, F.; Zengerle, R.

2011-06-01

The direct on-disk wireless temperature measurement system [1,2] presented at μTAS 2010 was further improved in its robustness. We apply it to an IR thermocycler as part of a centrifugal microfluidic analyzer for polymerase chain reactions (PCR). This IR thermocycler allows the very efficient direct heating of aqueous liquids in microfluidic cavities by an IR radiation source. The efficiency factor of this IR heating system depends on several parameters. First there is the efficiency of the IR radiator considering the transformation of electrical energy into radiation energy. This radiation energy needs to be focused by a reflector to the center of the cavity. Both, the reflectors shape and the quality of the reflecting layer affect the efficiency. On the way to the center of the cavity the radiation energy will be diminished by absorption in the surrounding air/humidity and especially in the cavity lid of the microfluidic disk. The transmission spectrum of the lid material and its thickness is of significant impact. We chose a COC polymer film with a thickness of 150 μm. At a peak frequency of the IR radiator of ~2 μm approximately 85 % of the incoming radiation energy passes the lid and is absorbed within the first 1.5 mm depth of liquid in the cavity. As we perform the thermocycling for a PCR, after heating to the denaturation temperature of ~ 92 °C we need to cool down rapidly to the primer annealing temperature of ~ 55 °C. Cooling is realized by 3 ventilators venting air of room temperature into the disk chamber. Due to the air flow itself and an additional rotation of the centrifugal microfluidic disk the PCR reagents in the cavities are cooled by forced air convection. Simulation studies based upon analogous electrical models enable to optimize the disk geometry and the optical path. Both the IR heater and the ventilators are controlled by the digital PID controller HAPRO 0135 [3]. The sampling frequency is set to 2 Hz. It could be further increased up to a maximum value being permitted by the wireless temperature data transmission system. As we are controlling a significantly non-linear process the controller parameters need to be optimized for all temperatures relevant for the PCR thermocycling process. Such we get a dynamic system for both, the heating and the cooling process. Heating rates up to 5 K/s with our IR heater (100 W electrical power) could be achieved. Cooling rates of instantly 1.3 K/s at 20 Hz rotation frequency could be even further increased by higher rotation frequencies, faster air circulation, optimization of the controller parameters or an active air cooling unit.

Water Plume Temperature Measurements by an Unmanned Aerial System (UAS)

PubMed Central

DeMario, Anthony; Lopez, Pete; Plewka, Eli; Wix, Ryan; Xia, Hai; Zamora, Emily; Gessler, Dan; Yalin, Azer P.

2017-01-01

We report on the development and testing of a proof of principle water temperature measurement system deployed on an unmanned aerial system (UAS), for field measurements of thermal discharges into water. The primary elements of the system include a quad-copter UAS to which has been integrated, for the first time, both a thermal imaging infrared (IR) camera and an immersible probe that can be dipped below the water surface to obtain vertical water temperature profiles. The IR camera is used to take images of the overall water surface to geo-locate the plume, while the immersible probe provides quantitative temperature depth profiles at specific locations. The full system has been tested including the navigation of the UAS, its ability to safely carry the sensor payload, and the performance of both the IR camera and the temperature probe. Finally, the UAS sensor system was successfully deployed in a pilot field study at a coal burning power plant, and obtained images and temperature profiles of the thermal effluent. PMID:28178215

Water Plume Temperature Measurements by an Unmanned Aerial System (UAS).

PubMed

DeMario, Anthony; Lopez, Pete; Plewka, Eli; Wix, Ryan; Xia, Hai; Zamora, Emily; Gessler, Dan; Yalin, Azer P

2017-02-07

We report on the development and testing of a proof of principle water temperature measurement system deployed on an unmanned aerial system (UAS), for field measurements of thermal discharges into water. The primary elements of the system include a quad-copter UAS to which has been integrated, for the first time, both a thermal imaging infrared (IR) camera and an immersible probe that can be dipped below the water surface to obtain vertical water temperature profiles. The IR camera is used to take images of the overall water surface to geo-locate the plume, while the immersible probe provides quantitative temperature depth profiles at specific locations. The full system has been tested including the navigation of the UAS, its ability to safely carry the sensor payload, and the performance of both the IR camera and the temperature probe. Finally, the UAS sensor system was successfully deployed in a pilot field study at a coal burning power plant, and obtained images and temperature profiles of the thermal effluent.

Infrared and X-Ray Spectroscopy of the Kes 75 Supernova Remnant Shell: Characterizing the Dust and Gas Properties

NASA Technical Reports Server (NTRS)

Temim, Tea; Slane, Patrick; Arendt, Richard G.; Dwek, Eli

2011-01-01

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of approximately 1.5 keY, or with two thermal components with temperatures of 1.5 and 0.2 keY. Previous studies suggest that the hot component may originate from reverse-shocked supernova (SN) ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from SN ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and IR emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modeling the IR spectrum shows that the dust is heated to a temperature of approximately 140 K by a relatively dense, hot plasma that also gives rise to the hot X-my emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-my emitting gas. The total mass of the warm dust component is at least 1.3 x 10(exp -2) x solar mass, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission. The complementary analyses of the X-ray and IR emission provide quantitative estimates of density and filling factors of the clumpy medium swept up by the SNR.

Infrared and X-Ray Spectroscopy of the Kes 75 Supernova Shell Characterizing the Dust and Gas Properties

NASA Technical Reports Server (NTRS)

Temim, Tea; Arendt, Richard G.; Dwek, Eli; Slane, Patrick

2012-01-01

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of approx 1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keY. Previous studies suggest that the hot component may originate from reverse-shocked SN ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from supernova (SN) ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and IR emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modeling the IR spectrum shows that the dust is heated to a temperature of approx 140 K by a relatively dense, hot plasma, that also gives rise to the hot X-ray emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-ray emitting gas. The total mass of the warm dust component is at least 1.3 x 10(exp -2) Solar Mass, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission. The complementary analyses of the X-ray and IR emission provide quantitative estimates of density and filling factors of the clumpy medium swept up by the SNR.

Infrared and X-Ray Spectroscopy of the Kes 75 Supernova Remnant Shell: Characterizing the Dust and Gas Properties

NASA Astrophysics Data System (ADS)

Temim, Tea; Slane, Patrick; Arendt, Richard G.; Dwek, Eli

2012-01-01

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of ~1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keV. Previous studies suggest that the hot component may originate from reverse-shocked supernova (SN) ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from SN ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and IR emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modeling the IR spectrum shows that the dust is heated to a temperature of ~140 K by a relatively dense, hot plasma that also gives rise to the hot X-ray emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-ray emitting gas. The total mass of the warm dust component is at least 1.3 × 10-2 M ⊙, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission. The complementary analyses of the X-ray and IR emission provide quantitative estimates of density and filling factors of the clumpy medium swept up by the SNR.

Hot and cold gas toward young stellar objects

NASA Technical Reports Server (NTRS)

Mitchell, George F.; Maillard, Jean-Pierre; Allen, Mark; Beer, Reinhard; Belcourt, Kenneth

1990-01-01

High-resolution M band spectra are presented for the seven embedded IR sources W3 IRS 5, S140 IRS1, NGC 7538 IRS 1, NGC 7538 IRS 9, GL 2136, LkH-alpha 101, and MWC 349A, and the data are combined with previously published work for W33A and GL 2591. Cold CO is seen toward all nine sources, with temperatures from 11 K to 66 K. Column densities of cold CO are presented. Hot gas is seen toward eight of the nine objects with temperatures from 120 K to 1010 K. New lower limits to the hot gas density are obtained. The hot gas toward GL 2591, GL 2136, W3 IRS 5, and S140 IRS 1 is probably very near the central source and heated via gas-grain collisions. The optical depth in the silicate feature is strongly correlated with the (C-13)O column density, confirming that silicate optical depth is a useful measure of gas column density. The ratio of solid-to-gaseous CO is obtained for seven sources.

Infrared measurements on ultraviolet photolysis products at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Dong, Weibing; He, Ping; Wang, Jessie; Zhou, Zhaohui; Wang, Hongxin

2013-01-01

Combination of ultraviolet (UV) photolysis with infrared (IR) spectroscopy (or UV/IR for abbreviation) is a powerful tool to study various chemical photoreactions, while cryostat and sample-cell windows define the working ranges for both UV and IR beams. Although diamond window has a very wide transmission range from UV to IR, the extreme cost, the absorptions at 1800-2600 cm-1 and other problems prevent it from being the solution for all cases. In this paper, a gas-exchange cryostat was modified to realize a UV/mid-IR experiment at cryogenic temperatures. Several windows (including diamond) were discussed as options. A di-nitrogen iron complex trans-[Fe(DMeOPrPE)2(N2)H][BPh4] [DMeOPrPE = 1,2-bis(dimethoxypropylphosphino)ethane] was studied as a real photolysis example. Alternatively, a cold-finger cryostat was modified for UV/far-IR compatible experiments. Non-photolysis samples K5[Mo4O11(R,S-Hhomocit)2]Cl·5H2O (H4homocit = homocitric acid) and [(n-Bu)4N]2[Fe4S4(PPh)4] were studied at cryogenic temperatures. Sample cell windows can also be used as a natural way for choosing photolysis wavelength (in addition to the use of optical filters).

A dual-band adaptor for infrared imaging.

PubMed

McLean, A G; Ahn, J-W; Maingi, R; Gray, T K; Roquemore, A L

2012-05-01

A novel imaging adaptor providing the capability to extend a standard single-band infrared (IR) camera into a two-color or dual-band device has been developed for application to high-speed IR thermography on the National Spherical Tokamak Experiment (NSTX). Temperature measurement with two-band infrared imaging has the advantage of being mostly independent of surface emissivity, which may vary significantly in the liquid lithium divertor installed on NSTX as compared to that of an all-carbon first wall. In order to take advantage of the high-speed capability of the existing IR camera at NSTX (1.6-6.2 kHz frame rate), a commercial visible-range optical splitter was extensively modified to operate in the medium wavelength and long wavelength IR. This two-band IR adapter utilizes a dichroic beamsplitter, which reflects 4-6 μm wavelengths and transmits 7-10 μm wavelength radiation, each with >95% efficiency and projects each IR channel image side-by-side on the camera's detector. Cutoff filters are used in each IR channel, and ZnSe imaging optics and mirrors optimized for broadband IR use are incorporated into the design. In-situ and ex-situ temperature calibration and preliminary data of the NSTX divertor during plasma discharges are presented, with contrasting results for dual-band vs. single-band IR operation.

Observation of temperature trace, induced by changing of temperature inside the human body, on the human body skin using commercially available IR camera

NASA Astrophysics Data System (ADS)

Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

2015-05-01

As it is well-known, application of the passive THz camera for the security problems is very promising way. It allows seeing concealed object without contact with a person and this camera is non-dangerous for a person. In previous papers, we demonstrate new possibility of the passive THz camera using for a temperature difference observing on the human skin if this difference is caused by different temperatures inside the body. For proof of validity of our statement we make the similar physical experiment using the IR camera. We show a possibility of temperature trace on human body skin, caused by changing of temperature inside the human body due to water drinking. We use as a computer code that is available for treatment of images captured by commercially available IR camera, manufactured by Flir Corp., as well as our developed computer code for computer processing of these images. Using both codes we demonstrate clearly changing of human body skin temperature induced by water drinking. Shown phenomena are very important for the detection of forbidden samples and substances concealed inside the human body using non-destructive control without X-rays using. Early we have demonstrated such possibility using THz radiation. Carried out experiments can be used for counter-terrorism problem solving. We developed original filters for computer processing of images captured by IR cameras. Their applications for computer processing of images results in a temperature resolution enhancing of cameras.

Estimate of the influence of muzzle smoke on function range of infrared system

NASA Astrophysics Data System (ADS)

Luo, Yan-ling; Wang, Jun; Wu, Jiang-hui; Wu, Jun; Gao, Meng; Gao, Fei; Zhao, Yu-jie; Zhang, Lei

2013-09-01

Muzzle smoke produced by weapons shooting has important influence on infrared (IR) system while detecting targets. Based on the theoretical model of detecting spot targets and surface targets of IR system while there is muzzle smoke, the function range for detecting spot targets and surface targets are deduced separately according to the definition of noise equivalent temperature difference(NETD) and minimum resolution temperature difference(MRTD). Also parameters of muzzle smoke affecting function range of IR system are analyzed. Base on measured data of muzzle smoke for single shot, the function range of an IR system for detecting typical targets are calculated separately while there is muzzle smoke and there is no muzzle smoke at 8-12 micron waveband. For our IR system function range has reduced by over 10% for detecting tank if muzzle smoke exists. The results will provide evidence for evaluating the influence of muzzle smoke on IR system and will help researchers to improve ammo craftwork.

Decoupling of magnetism and electric transport in single-crystal (Sr1‑x A x )2IrO4 (A  =  Ca or Ba)

NASA Astrophysics Data System (ADS)

Zhao, H. D.; Terzic, J.; Zheng, H.; Ni, Y. F.; Zhang, Y.; Ye, Feng; Schlottmann, P.; Cao, G.

2018-06-01

We report a systematical structural, transport and magnetic study of Ca or Ba doped Sr2IrO4 single crystals. Isoelectronically substituting Ca2+ (up to 15%) or Ba2+ (up to 4%) ion for the Sr2+ ion provides no additional charge carriers but effectively changes the lattice parameters in Sr2IrO4. In particular, 15% Ca doping considerably reduces the c-axis and the unit cell by nearly 0.45% and 1.00%, respectively. These significant, anisotropic compressions in the lattice parameters conspicuously cause no change in the Néel temperature which remains at 240 K, but drastically reduces the electrical resistivity by up to five orders of magnitude or even precipitates a sharp insulator-to-metal transition at lower temperatures, i.e. the vanishing insulating state accompanies an unchanged Néel temperature in (Sr1‑x A x )2IrO4. This observation brings to light an intriguing difference between chemical pressure and applied pressure, the latter of which does suppress the long-range magnetic order in Sr2IrO4. This difference reveals the importance of the Ir1–O2–Ir1 bond angle and homogenous volume compression in determining the magnetic ground state. All results, along with a comparison drawn with results of Tb and La doped Sr2IrO4, underscore that the magnetic transition plays a nonessential role in the formation of the charge gap in the spin–orbit-tuned iridate.

Dynamics and Interactions in Room Temperature Ionic Liquids, Surfaces and Interfaces

DTIC Science & Technology

2016-01-13

OHD-OKE) experiments. The first 2D IR experiments on functionalized SiO2 planar surface monolayers of alkyl chains with a vibrational probe head group...alkyl groups lowers the temperature for crystallization below room temperature and can also result in supercooling and glass formation rather than...heterodyne detected optical Kerr effect (OHD-OKE) experiments. During the grant, we performed the first 2D IR experiments on functionalized SiO2

Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas

DTIC Science & Technology

2014-09-30

developed by incorporating the proposed IR sensors and ground-sky temperature difference algorithm into a tethered balloon borne payload (Figure 3...into the cloud base. RESULTS FROM FY 2014 • A second flight of the tethered balloon -borne IR cloud margin sensor was conducted in Colorado on...Figure 3: Tethered balloon -borne IR sensing payload IR Cloud Margin Sensor Figure 4: First successful flight validation of the IR cloud

Development of an inverse distance weighted active infrared stealth scheme using the repulsive particle swarm optimization algorithm.

PubMed

Han, Kuk-Il; Kim, Do-Hwi; Choi, Jun-Hyuk; Kim, Tae-Kuk

2018-04-20

Treatments for detection by infrared (IR) signals are higher than for other signals such as radar or sonar because an object detected by the IR sensor cannot easily recognize its detection status. Recently, research for actively reducing IR signal has been conducted to control the IR signal by adjusting the surface temperature of the object. In this paper, we propose an active IR stealth algorithm to synchronize IR signals from the object and the background around the object. The proposed method includes the repulsive particle swarm optimization statistical optimization algorithm to estimate the IR stealth surface temperature, which will result in a synchronization between the IR signals from the object and the surrounding background by setting the inverse distance weighted contrast radiant intensity (CRI) equal to zero. We tested the IR stealth performance in mid wavelength infrared (MWIR) and long wavelength infrared (LWIR) bands for a test plate located at three different positions on a forest scene to verify the proposed method. Our results show that the inverse distance weighted active IR stealth technique proposed in this study is proved to be an effective method for reducing the contrast radiant intensity between the object and background up to 32% as compared to the previous method using the CRI determined as the simple signal difference between the object and the background.

Improving aerosol vertical retrieval for NWP application: Studying the impact of IR-sensed aerosol on data assimilation systems.

NASA Astrophysics Data System (ADS)

Oyola, Mayra; Marquis, Jared; Ruston, Benjamin; Campbell, James; Baker, Nancy; Westphal, Douglas; Zhang, Jianglong; Hyer, Edward

2017-04-01

Radiometric measurements from passive infrared (IR) sensors are important in numerical weather prediction (NWP) because they are sensitive to surface temperatures and atmospheric temperature profiles. However, these measurements are also sensitive to absorbing and scattering constituents in the atmosphere. Dust aerosols absorb in the IR and are found over many global regions with irregular spatial and temporal frequency. Retrievals of temperature using IR data are thus vulnerable to dust-IR radiance biases, most notably over tropical oceans where accurate surface and atmospheric temperatures are critical to accurate prediction of tropical cyclone development. Previous studies have shown that dust aerosols can bias retrieved brightness temperatures (BT) by up to 10K in some IR channels that are assimilated to constrain atmospheric temperature and water vapor profiles. Other BT-derived parameters such as sea surface temperatures (SSTs) are susceptible to negative biases of at least 1K or higher, which conflicts with the accuracy requirement for most research and operational applications (i.e., +/- 0.3 K). This problem is not limited to just satellite retrievals. BT bias also impacts the incorporation of background fields from NWP analyses in data assimilation (DA) systems. The effect of aerosols on IR fluxes at the ocean surface is a function of both aerosol loading and vertical profile. Therefore, knowledge of the aerosol vertical distribution, and understanding of how well this distribution is captured by NWP models, is necessary to ensuring proper treatment of aerosol-affected radiances in both retrieval and data assimilation. This understanding can be achieved by conducting modeling studies and by the exploitation of a robust observational dataset, such as satellite-based lidar profiling, which can be used to characterize aerosol type and distribution. In this talk, we describe such an application using the Navy Aerosol Analysis Prediction System (NAAPS) and Naval Research Laboratory (NRL) Atmospheric Variational Data Assimilation System (NAVDAS). We describe the impact of aerosol-biased radiances on operational DA, and thus the quantitative impact of dust on model profiles of temperature and water vapor mixing ratio before and after data assimilation, using collocated hyperspectral Cross-track Infrared Sounder (CrIs) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) observations over the Tropical Atlantic. We then describe how the NAVDAS radiance assimilation system responds when coupled with NAAPS dust concentration fields, and thus how the model representation of dust compares with observations.. The result is a conceptual description of how IR-absorbing dust impacts radiance DA for operational weather modeling, and a first-order description of how adept current aerosol transport models are for providing compulsory corrections.

Theoretical and experimental studies of hydrogen adsorption and desorption on Ir surfaces

DOE PAGES

Kaghazchi, Payam; Jacob, Timo; Chen, Wenhua; ...

2013-06-03

Here, we report adsorption and desorption of hydrogen on planar Ir(210) and faceted Ir(210), consisting of nanoscale {311} and (110) facets, by means of temperature programmed desorption (TPD) and density functional theory (DFT) in combination with the ab initio atomistic thermodynamics approach. TPD spectra show that only one H 2 peak is seen from planar Ir(210) at all coverages whereas a single H 2 peak is observed at around 440 K (F1) at fractional monolayer (ML) coverage and an additional H 2 peak appears at around 360 K (F2) at 1 ML coverage on faceted Ir(210), implying structure sensitivity inmore » recombination and desorption of hydrogen on faceted Ir(210) versus planar Ir(210), but no evidence is found for size effects in recombination and desorption of hydrogen on faceted Ir(210) for average facet sizes of 5-14 nm. Calculations indicate that H prefers to bind at the two-fold short-bridge sites of the Ir surfaces. In addition, we studied the stability of the Ir surfaces in the presence of hydrogen at different H coverages through surface free energy plots as a function of the chemical potential, which is also converted to a temperature scale. Moreover, the calculations revealed the origin of the two TPD peaks of H 2 from faceted Ir(210): F1 from desorption of H 2 on {311} facets while F2 from desorption of H 2 on (110) facets.« less

Impact of neuromuscular fatigue on match exercise intensity and performance in elite Australian football.

PubMed

Mooney, Mitchell G; Cormack, Stuart; Oʼbrien, Brendan J; Morgan, William M; McGuigan, Mike

2013-01-01

This study aimed to quantify the influence of neuromuscular fatigue (NMF) via flight time to contraction time ratio (FT:CT) obtained from a countermovement jump (CMJ) on the relationships between yo-yo intermittent recovery (level 2) test (yo-yo IR2), match exercise intensity (high-intensity running [HIR] m·min(-1) and Load·min(-1)) and Australian football (AF) performance. Thirty-seven data sets were collected from 17 different players across 22 elite AF matches. Each data set comprised an athlete's yo-yo IR2 score before the start of the season, match exercise intensity via global positioning system and on-field performance rated by coaches' votes and number of ball disposals. Each data set was categorized as normal (>92% baseline FT:CT, n = 20) or fatigued (<92% baseline FT:CT, n = 17) from a single CMJ performed 96 hours after the previous match. Moderation-mediation analysis was completed with yo-yo IR2 (independent variable), match exercise intensity (mediator), and AF performance (dependent variable) with NMF status as the conditional variable. Isolated interactions between variables were analyzed by Pearson's correlation and effect size statistics. The Yo-yo IR2 score showed an indirect influence on the number of ball disposals via HIR m·min(-1) regardless of NMF status (normal FT:CT indirect effect = 0.019, p < 0.1, reduced FT:CT indirect effect = 0.022, p < 0.1). However, the yo-yo IR2 score only influenced coaches' votes via Load·min(-1) in the nonfatigued state (normal: FT:CT indirect effect = 0.007, p <0.1, reduced: FT:CT indirect effect = -0.001, p > 0.1). In isolation, NMF status also reduces relationships between yo-yo IR2 and load·min(-1), yo-yo IR2 and coaches votes, Load·min(-1) and coaches' votes (Δr > 0.1). Routinely testing yo-yo IR2 capacity, NMF via FT:CT and monitoring Load·min(-1) in conjunction with HIR m·min(-1) as exercise intensity measures in elite AF is recommended.

Glucose Homeostasis Variables in Pregnancy versus Maternal and Infant Body Composition

PubMed Central

Henriksson, Pontus; Löf, Marie; Forsum, Elisabet

2015-01-01

Intrauterine factors influence infant size and body composition but the mechanisms involved are to a large extent unknown. We studied relationships between the body composition of pregnant women and variables related to their glucose homeostasis, i.e., glucose, HOMA-IR (homeostasis model assessment-insulin resistance), hemoglobin A1c and IGFBP-1 (insulin-like growth factor binding protein-1), and related these variables to the body composition of their infants. Body composition of 209 women in gestational week 32 and of their healthy, singleton and full-term one-week-old infants was measured using air displacement plethysmography. Glucose homeostasis variables were assessed in gestational week 32. HOMA-IR was positively related to fat mass index and fat mass (r2 = 0.32, p < 0.001) of the women. Maternal glucose and HOMA-IR values were positively (p ≤ 0.006) associated, while IGFBP-1was negatively (p = 0.001) associated, with infant fat mass. HOMA-IR was positively associated with fat mass of daughters (p < 0.001), but not of sons (p = 0.65) (Sex-interaction: p = 0.042). In conclusion, glucose homeostasis variables of pregnant women are related to their own body composition and to that of their infants. The results suggest that a previously identified relationship between fat mass of mothers and daughters is mediated by maternal insulin resistance. PMID:26184296

Facile Dehydrogenation of Ethane on the IrO2(110) Surface.

PubMed

Bian, Yingxue; Kim, Minkyu; Li, Tao; Asthagiri, Aravind; Weaver, Jason F

2018-02-21

Realizing the efficient and selective conversion of ethane to ethylene is important for improving the utilization of hydrocarbon resources, yet remains a major challenge in catalysis. Herein, ethane dehydrogenation on the IrO 2 (110) surface is investigated using temperature-programmed reaction spectroscopy (TPRS) and density functional theory (DFT) calculations. The results show that ethane forms strongly bound σ-complexes on IrO 2 (110) and that a large fraction of the complexes undergo C-H bond cleavage during TPRS at temperatures below 200 K. Continued heating causes as much as 40% of the dissociated ethane to dehydrogenate and desorb as ethylene near 350 K, with the remainder oxidizing to CO x species. Both TPRS and DFT show that ethylene desorption is the rate-controlling step in the conversion of ethane to ethylene on IrO 2 (110) during TPRS. Partial hydrogenation of the IrO 2 (110) surface is found to enhance ethylene production from ethane while suppressing oxidation to CO x species. DFT predicts that hydrogenation of reactive oxygen atoms of the IrO 2 (110) surface effectively deactivates these sites as H atom acceptors, and causes ethylene desorption to become favored over further dehydrogenation and oxidation of ethane-derived species. The study reveals that IrO 2 (110) exhibits an exceptional ability to promote ethane dehydrogenation to ethylene near room temperature, and provides molecular-level insights for understanding how surface properties influence selectivity toward ethylene production.

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

Wang, Pei; Wang, Yonggang; Wang, Liping

Cubic (space group: Fm3¯m) iridium phosphide, Ir 2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir 2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B 0 = 306(6) GPa and its pressure derivative B 0'= 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first – principles calculations and three-dimensionally distributed [IrP 4] tetrahedron network. Indentation testing on a well–sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively lowmore » shear modulus of ~64 GPa from theoretical calculations suggests a complicated overall bonding in Ir 2P with metallic, ionic, and covalent characteristics. Additionally, a spin glass behavior is indicated by magnetic susceptibility measurements.« less

Direct analysis of terpenes from biological buffer systems using SESI and IR-MALDESI.

PubMed

Nazari, Milad; Malico, Alexandra A; Ekelöf, Måns; Lund, Sean; Williams, Gavin J; Muddiman, David C

2018-01-01

Terpenes are the largest class of natural products with a wide range of applications including use as pharmaceuticals, fragrances, flavorings, and agricultural products. Terpenes are biosynthesized by the condensation of a variable number of isoprene units resulting in linear polyisoprene diphosphate units, which can then be cyclized by terpene synthases into a range of complex structures. While these cyclic structures have immense diversity and potential in different applications, their direct analysis in biological buffer systems requires intensive sample preparation steps such as salt cleanup, extraction with organic solvents, and chromatographic separations. Electrospray post-ionization can be used to circumvent many sample cleanup and desalting steps. SESI and IR-MALDESI are two examples of ionization methods that employ electrospray post-ionization at atmospheric pressure and temperature. By coupling the two techniques and doping the electrospray solvent with silver ions, olefinic terpenes of different classes and varying degrees of volatility were directly analyzed from a biological buffer system with no sample workup steps.

Recent Developments on Airborne Forward Looking Interferometer for the Detection of Wake Vortices

NASA Technical Reports Server (NTRS)

Daniels, Taumi S.; Smith, William L.; Kirev, Stanislav

2012-01-01

A goal of these studies was development of the measurement methods and algorithms necessary to detect wake vortex hazards in real time from either an aircraft or ground-based hyperspectral Fourier Transform Spectrometer (FTS). This paper provides an update on research to model FTS detection of wake vortices. The Terminal Area Simulation System (TASS) was used to generate wake vortex fields of 3-D winds, temperature, and absolute humidity. These fields were input to the Line by Line Radiative Transfer Model (LBLRTM), a hyperspectral radiance model in the infrared, employed for the FTS numerical modeling. An initial set of cases has been analyzed to identify a wake vortex IR signature and signature sensitivities to various state variables. Results from the numerical modeling case studies will be presented. Preliminary results indicated that an imaging IR instrument sensitive to six narrow bands within the 670 to 3150 per centimeter spectral region would be sufficient for wake vortex detection. Noise floor estimates for a recommended instrument are a current research topic.

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

Gilbertson, Robert D.; Patterson, Brian M.; Smith, Zachary

An accelerated aging study of BKC 44306-10 rigid polyurethane foam was carried out. Foam samples were aged in a nitrogen atmosphere at three different temperatures: 50 °C, 65 °C, and 80 °C. Foam samples were periodically removed from the aging canisters at 1, 3, 6, 9, 12, and 15 month intervals when FT-IR spectroscopy, dimensional analysis, and mechanical testing experiments were performed. Micro Computed Tomography imaging was also employed to study the morphology of the foams. Over the course of the aging study the foams the decreased in size by a magnitude of 0.001 inches per inch of foam. Micromore » CT showed the heterogeneous nature of the foam structure likely resulting from flow effects during the molding process. The effect of aging on the compression and tensile strength of the foam was minor and no cause for concern. FT-IR spectroscopy was used to follow the foam chemistry. However, it was difficult to draw definitive conclusions about the changes in chemical nature of the materials due to large variability throughout the samples.« less

High-pressure high-temperature stability of hcp-Ir xOs 1-x (x = 0.50 and 0.55) alloys

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

Yusenko, Kirill V.; Bykova, Elena; Bykov, Maxim

2016-12-23

Hcp-Ir 0.55Os 0.45 and hcp-Ir 0.50Os 0.50 alloys were synthesised by thermal decomposition of single-source precursors in hydrogen atmosphere. Both alloys correspond to a miscibility gap in the Ir–Os binary phase diagram and therefore are metastable at ambient conditions. An in situ powder X-ray diffraction has been used for a monitoring a formation of hcp-Ir0.55Os0.45 alloy from (NH 4) 2[Ir 0.55Os 0.45Cl 6] precursor. A crystalline intermediate compound and nanodimentional metallic particles with a large concentration of defects has been found as key intermediates in the thermal decomposition process in hydrogen flow. High-temperature stability of titled hcp-structured alloys has beenmore » investigated upon compression up to 11 GPa using a multi-anvil press and up to 80 GPa using laser-heated diamond-anvil cells to obtain a phase separation into fcc + hcp mixture. Compressibility curves at room temperature as well as thermal expansion at ambient pressure and under compression up to 80 GPa were collected to obtain thermal expansion coefficients and bulk moduli. hcp-Ir 0.55Os 0.45 alloy shows bulk moduli B0 = 395 GPa. Thermal expansion coefficients were estimated as α = 1.6·10 -5 K -1 at ambient pressure and α = 0.3·10 -5 K -1 at 80 GPa. Obtained high-pressure high-temperature data allowed us to construct the first model for pressure-dependent Ir–Os phase diagram.« less

Growth and phase transformations of Ir on Ge(111)

NASA Astrophysics Data System (ADS)

Mullet, C. H.; Stenger, B. H.; Durand, A. M.; Morad, J. A.; Sato, Y.; Poppenheimer, E. C.; Chiang, S.

2017-12-01

The growth of Ir on Ge(111) as a function of temperature between 23 °C and 820 °C is characterized with low energy electron microscopy (LEEM), low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and x-ray photoemission spectroscopy (XPS). Deposition onto a substrate at 350 °C revealed a novel growth mode consisting of multilayer Ir islands with (√3 × √3)R30° (abbreviated as √3) structure interconnected by ;bridges; of single-layer Ir several atoms wide. For deposition onto substrates above 500 °C, the √3 Ir phase grows with dendritic morphology, and substrate step bunches act as barriers to √3 Ir growth. LEEM images showed Stranski-Krastanov growth for 650-820 °C: after the √3 phase covers the surface, corresponding to 2 monolayers (ML) Ir coverage, multilayer hexagonal-shaped Ir islands form, surrounded by regions of IrGe alloy. Hexagonal-shaped Ir islands also formed upon heating 1.2 ML of √3 Ir beyond 830 °C, which resulted in the elimination of √3 structure from the surface. The transformation from √3 to (1 × 1) structure upon heating to 830 °C was an irreversible surface phase transition. Annealing > 2.0 ML of Ir in the √3 phase above the 830 °C disorder temperature, followed by cooling, produced a (3 × 1) structure. Subsequent heating and cooling through 830 °C give evidence for a reversible (3 × 1) to (1 × 1) phase transition.

IR Variability of Eta Carinae

NASA Astrophysics Data System (ADS)

Smith, Nathan

2008-02-01

Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron, and the next periastron event will occur at the very end of 2008. In addition, η Car shows long term changes as it is still recovering from its giant 19th century outburst. Both types of variability are directly linked to the current mass-loss rate and dust formation in its wind. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and a direct measure of the massw in dust formation episodes that may occur at periastron in the colliding wind shock. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with Phoenix will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula.

IR Variability During a Shell Ejection of Eta Carinae

NASA Astrophysics Data System (ADS)

Smith, Nathan

2006-02-01

Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to a very eccentric binary system with a shell ejection occurring at periastron. Mid-IR images and spectra with T-ReCS are needed to measure changes in the current bolometric luminosity and to trace dust formation episodes. This will provide a direct estimate of the mass ejected. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with GNIRS will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula. The complex kinematic structure of η Car's ejecta also holds important clues to its mass ejection history, and is essential for interpreting other data. Phoenix can provide a unique kinematic map of the complex density and time-variable ionization structure of η Car's nebula, which is our best example of the pre-explosion environment of very massive stars.

The EarthCARE multi spectral imager thermal infrared optical unit

NASA Astrophysics Data System (ADS)

Chang, M. P. J. L.; Woods, D.; Baister, Guy; Lobb, Dan; Wood, Trevor

2017-11-01

The EarthCARE satellite mission objective is the observation of clouds and aerosols from low Earth orbit. The key spatial context providing instrument within the payload suite of 4 instruments is the Multi-Spectral Imager (MSI), previously described in [1]. The MSI is intended to provide information on the horizontal variability of the atmospheric conditions and to identify e.g. cloud type, textures, and temperature. It will form Earth images at 500m ground sample distance (GSD) over a swath width of 150km; it will image Earth in 7 spectral bands: one visible, one near-IR, two short-wave IR and three thermal IR. The instrument will be comprised of two key parts: • a visible-NIR-SWIR (VNS) optical unit radiometrically calibrated using a sun illuminated quasivolume diffuser and shutter system • a thermal IR (TIR) optical unit radiometrically calibrated using cold space and an internal black-body. This paper, being the first of a sequence of two, will provide an overview of the MSI and enter into more detail the critical performance parameters and detailed design the MSI TIR optical design. The TIR concept is to provide pushbroom imaging of its 3 bands through spectral separation from a common aperture. The result is an efficient, well controlled optical design without the need for multiple focal plane arrays. The designed focal plane houses an area array detector and will meet a challenging set of requirements, including radiometric resolution, accuracy, distortion and MTF.

Observation of non-Fermi liquid behavior in hole-doped Eu2Ir2O7

NASA Astrophysics Data System (ADS)

Banerjee, A.; Sannigrahi, J.; Giri, S.; Majumdar, S.

2017-12-01

The Weyl semimetallic compound Eu2Ir2O7 and its hole-doped derivatives (which are achieved by substituting trivalent Eu by divalent Sr) are investigated through transport, magnetic, and calorimetric studies. The metal-insulator transition (MIT) temperature is found to get substantially reduced with hole doping, and for 10% Sr doping the composition is metallic down to temperature as low as 5 K. These doped compositions are found to violate the Mott-Ioffe-Regel condition for minimum electrical conductivity and show a distinct signature of non-Fermi liquid behavior at low temperature. The MIT in the doped compounds does not correlate with the magnetic transition point, and Anderson-Mott-type disorder-induced localization may be attributed to the ground-state insulating phase. The observed non-Fermi liquid behavior can be understood on the basis of disorder-induced distribution of the spin-orbit-coupling parameter, which is markedly different in the case of Ir4 + and Ir5 + ions.

Honey bee odorant-binding protein 14: effects on thermal stability upon odorant binding revealed by FT-IR spectroscopy and CD measurements.

PubMed

Schwaighofer, Andreas; Kotlowski, Caroline; Araman, Can; Chu, Nam; Mastrogiacomo, Rosa; Becker, Christian; Pelosi, Paolo; Knoll, Wolfgang; Larisika, Melanie; Nowak, Christoph

2014-03-01

In the present work, we study the effect of odorant binding on the thermal stability of honey bee (Apis mellifera L.) odorant-binding protein 14. Thermal denaturation of the protein in the absence and presence of different odorant molecules was monitored by Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD). FT-IR spectra show characteristic bands for intermolecular aggregation through the formation of intermolecular β-sheets during the heating process. Transition temperatures in the FT-IR spectra were evaluated using moving-window 2D correlation maps and confirmed by CD measurements. The obtained results reveal an increase of the denaturation temperature of the protein when bound to an odorant molecule. We could also discriminate between high- and low-affinity odorants by determining transition temperatures, as demonstrated independently by the two applied methodologies. The increased thermal stability in the presence of ligands is attributed to a stabilizing effect of non-covalent interactions between odorant-binding protein 14 and the odorant molecule.

Infrared and X-Ray Spectroscopy of the KES 75 Supernova Remnant Shell: Characterizing the Dust and Gas Properties

NASA Technical Reports Server (NTRS)

Temim, Tea; Dwek, Eli; Slane, Patrick; Arendt, Richard G.

2009-01-01

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of 1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keV. Previous studies suggest that the hot component may originate from reverse-shocked SN ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from supernova (SN) ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and ill emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modeling the IR spectrum shows that the dust is heated to a temperature of 140 K by a relatively dense, hot plasma, that also gives rise to the hot X-ray emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-ray emitting gas. The total mass of the warm dust component is at least 1.3 x 10(exp -2) solar mass, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission. The complementary analyses of the X-ray and IR emission provide quantitative estimates of density and filling factors of the clumpy medium swept up by the SNR.

The Moderating Effect of Religion on the Relationship Between Depression and Suicidal Ideation in the Elderly.

PubMed

Jung, JaeHoon; Roh, Daeyoung; Moon, Yoo Sun; Kim, Do Hoon

2017-08-01

This article aimed to compare the level of suicidal ideation in the religiously affiliated and nonaffiliated groups and identify the moderating effect of religion variables on the relationship between depression and suicidal ideation. The sample in this study was 1180 residents who were older than 60 years and who resided in Gangwon Province, South Korea. We studied the cross-sectional relationships among religions and studied variables including organizational religious activity (ORA), non-ORA (NORA), intrinsic religiosity (IR), depression, well-being, and suicidal ideation. After controlling for sociodemographic variables, the depression, well-being, and suicidal ideation level in the religiously affiliated group were not significantly different from that of the religiously nonaffiliated group and the variables also were not significantly different between Christians and Buddhists. The effect of depression on suicidal ideation was significantly moderated by ORA and IR, and the effect showed different patterns by religion; ORA was a moderator only among the Buddhist group, and IR only moderated the relationships among the Christians.

Noncontact detection of dry eye using a custom designed IR thermal image system

NASA Astrophysics Data System (ADS)

Su, Tai Yuan; Chen, Kerh Hwa; Liu, Po Hsuan; Wu, Ming Hong; Chang, David O.; Chiang, Huihua

2011-03-01

Dry eye syndrome is a common irritating eye disease. Current clinical diagnostic methods are invasive and uncomfortable to patients. A custom designed noncontact infrared (IR) thermal image system was developed to measure the spatial and temporal variation of the ocular surface temperature over a 6-second eye-opening period. We defined two parameters: the temperature difference value and the compactness value to represent the degree of the temperature change and irregularity of the temperature distribution on the tear film. By using these two parameters, in this study, a linear discrimination result for the dry eye and the normal eye groups; the sensitivity is 0.9, the specificity is 0.86 and the receiver operating characteristic (ROC) area is 0.91. The result suggests that the custom designed IR thermal image system may be used as an effective tool for noncontact detection of dry eye.

Dryland pasture and crop conditions as seen by HCMM. [Washita River watershed, Oklahoma

NASA Technical Reports Server (NTRS)

Rosenthal, W. D.; Harlan, J. C.; Blanchard, B. J. (Principal Investigator)

1980-01-01

Ground truth, aircraft, and satellite data were examined in order to: (1) assess the capability for determining wheat and pasture canopy temperatures in a dryland farming region from HCMM data; (2) assess the capability for determining soil moisture from HCMM data in dryland crops (winter wheat) from adjacent range lands; and (3) determine the relationship of HCMM-derived soil moisture and canopy temperature values with the condition of winter wheat and dryland farming areas during the principal growth stages. The IR data were screened to include areas having greater than 60% pasture and surface temperatures were recalculated using the atmospheric correction factor calculated by the modified RADTRA model, and the July 29, 1978 IR data were analyzed. Screening the IR data improved the relationship for July 24/July 13 and October 7/August 31 temperature/API relationship. However the coefficient of determination was not improved in the July 29/July 13 relationship.

High-pressure synthesis and structural, physical properties of CaIr1-xPtxO3 and CaIr1-xRhxO3

NASA Astrophysics Data System (ADS)

Hirai, S.; Bromiley, G. D.; Klemme, S.; Irifune, T.; Ohfuji, H.; Attfield, P.; Nishiyama, N.

2010-12-01

Since the discovery of the perovskite to post-perovskite transition in MgSiO3 in a laser-heated DAC, wide attention has been focussed on the post-perovskite phase of MgSiO3. This is because the post-perovskite phase is likely to play a key role in Earth’s lowermost mantle, and because the perovskite to post-perovskite transition can explain many features of the D” seismic discontinuity. While it is meaningful to conduct further studies of MgSiO3, the post-perovskite phase of MgSiO3 cannot be quenched to ambient pressure/temperature conditions. Thus, further studies must be conducted using analogue compounds of MgSiO3 post-perovskite, which are quenchable to ambient pressure/temperature conditions. The post-perovskite phase of MgSiO3 crystallizes in a layered structure with CaIrO3-structure. Therefore, it is useful to investigate compounds with CaIrO3-structure. There are only four quenchable oxides with CaIrO3-structure reported to date: CaIrO3, CaPtO3, CaRhO3 and CaRuO3. CaIrO3 can be synthesized at ambient pressure, whilst the other three oxides can only be obtained at high pressure/temperature conditions using a multi-anvil apparatus. Further studies on these materials have revealed structural phase transitions at high P-T and a metal-insulator transition by hole doping. In the case of CaIrO3, The post-perovskite phase of CaIrO3 synthesized at 2GPa, 1373K transforms into a perovskite phase at 2GPa, 1673K. In other words, the perovskite phase can be synthesized at temperatures higher than those needed for synthesizing the post-perovskite phase. This is also the case for CaRhO3 (6GPa, 1873K) and CaRuO3 (23GPa, 1343K), while CaPtO3 remained post-perovskite at higher temperatures. We have succeeded in synthesizing solid solutions between CaIrO3, CaPtO3 and CaRhO3. We have found the systematic change in structural and physical properties of post-perovskite oxides, with composition and P-T, which broadens the future opportunity for studying post-perovskite systems in terms of materials science applications. To our knowledge, this will be the first report on structural, magnetic and charge-transport properties of B-site substituted solid solutions of post-perovskite oxides with 4d/5d transition metals. High-quality polycrystalline samples of CaIr1-xPtxO3 and CaIr1-xRhxO3 have been obtained at high pressures, and structural, magnetic and charge-transport properties of the compounds will be reported. ODF analysis reveals that solutions of CaIrO3, CaPtO3 and CaRhO3 exhibit similar grain growth features to the mother compound, although growth in [0 1 0] plays a more dominant role than the growth in [0 0 1] for the solid solutions. CaIrO3 is a characteristic hard magnet suitable for applications such as magnetic recording, with TN = 108K. A new phase of CaIr1-xPtxO3 synthesized at a high P/T condition has Raman modes which resemble those of CaIrO3 perovskite, suggesting this phase has a perovskite structure.The instability of the perovskite phase of CaIr1-xPtxO3 reveals why the post-perovskite to peovskite phase transition has not been observed for CaPtO3 unlike the case for CaIrO3, CaRhO3 and CaRuO3.

Prevalence of Non-responders for Glucose Control Markers after 10 Weeks of High-Intensity Interval Training in Adult Women with Higher and Lower Insulin Resistance.

PubMed

Álvarez, Cristian; Ramírez-Campillo, Rodrigo; Ramírez-Vélez, Robinson; Izquierdo, Mikel

2017-01-01

Background: Exercise training improves performance and biochemical parameters on average, but wide interindividual variability exists, with individuals classified as responders (R) or non-responders (NRs), especially between populations with higher or lower levels of insulin resistance. This study assessed the effects of high-intensity interval training (HIIT) and the prevalence of NRs in adult women with higher and lower levels of insulin resistance. Methods: Forty adult women were assigned to a HIIT program, and after training were analyzed in two groups; a group with higher insulin resistance (H-IR, 40 ± 6 years; BMI: 29.5 ± 3.7 kg/m 2 ; n = 20) and a group with lower insulin resistance (L-IR, 35 ± 9 years; 27.8 ± 2.8 kg/m 2 ; n = 20). Anthropometric, cardiovascular, metabolic, and performance variables were measured at baseline and after 10 weeks of training. Results: There were significant training-induced changes [delta percent (Δ%)] in fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) scores in the H-IR group (-8.8, -26.5, -32.1%, p < 0.0001), whereas no significant changes were observed in the L-IR. Both groups showed significant pre-post changes in other anthropometric variables [waist circumference (-5.2, p < 0.010, and -3.8%, p = 0.046) and tricipital (-13.3, p < 0.010, and -13.6%, p < 0.0001), supra-iliac (-19.4, p < 0.0001, and -13.6%, p < 0.0001), and abdominal (-18.2, p < 0.0001, and -15.6%, p < 0.010) skinfold measurements]. Systolic blood pressure decreased significantly only in the L-IR group (-3.2%, p < 0.010). Both groups showed significant increases in 1RM LE (+12.9, p < 0.010, and +14.7%, p = 0.045). There were significant differences in the prevalence of NRs between the H-IR and L-IR groups for fasting glucose (25 vs. 95%, p < 0.0001) and fasting insulin ( p = 0.025) but not for HOMA-IR (25 vs. 45%, p = 0.185). Conclusion: Independent of the "magnitude" of the cardiometabolic disease (i.e., higher vs. lower insulin resistance), no differences were observed in the NRs prevalence with regard to improved HOMA-IR or to anthropometric, cardiovascular, and muscle performance co-variables after 10 weeks of HIIT in sedentary adult women. This research demonstrates the protective effect of HIIT against cardiometabolic disease progression in a sedentary population.

Prevalence of Non-responders for Glucose Control Markers after 10 Weeks of High-Intensity Interval Training in Adult Women with Higher and Lower Insulin Resistance

PubMed Central

Álvarez, Cristian; Ramírez-Campillo, Rodrigo; Ramírez-Vélez, Robinson; Izquierdo, Mikel

2017-01-01

Background: Exercise training improves performance and biochemical parameters on average, but wide interindividual variability exists, with individuals classified as responders (R) or non-responders (NRs), especially between populations with higher or lower levels of insulin resistance. This study assessed the effects of high-intensity interval training (HIIT) and the prevalence of NRs in adult women with higher and lower levels of insulin resistance. Methods: Forty adult women were assigned to a HIIT program, and after training were analyzed in two groups; a group with higher insulin resistance (H-IR, 40 ± 6 years; BMI: 29.5 ± 3.7 kg/m2; n = 20) and a group with lower insulin resistance (L-IR, 35 ± 9 years; 27.8 ± 2.8 kg/m2; n = 20). Anthropometric, cardiovascular, metabolic, and performance variables were measured at baseline and after 10 weeks of training. Results: There were significant training-induced changes [delta percent (Δ%)] in fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) scores in the H-IR group (−8.8, −26.5, −32.1%, p < 0.0001), whereas no significant changes were observed in the L-IR. Both groups showed significant pre-post changes in other anthropometric variables [waist circumference (−5.2, p < 0.010, and −3.8%, p = 0.046) and tricipital (−13.3, p < 0.010, and −13.6%, p < 0.0001), supra-iliac (−19.4, p < 0.0001, and −13.6%, p < 0.0001), and abdominal (−18.2, p < 0.0001, and −15.6%, p < 0.010) skinfold measurements]. Systolic blood pressure decreased significantly only in the L-IR group (−3.2%, p < 0.010). Both groups showed significant increases in 1RMLE (+12.9, p < 0.010, and +14.7%, p = 0.045). There were significant differences in the prevalence of NRs between the H-IR and L-IR groups for fasting glucose (25 vs. 95%, p < 0.0001) and fasting insulin (p = 0.025) but not for HOMA-IR (25 vs. 45%, p = 0.185). Conclusion: Independent of the “magnitude” of the cardiometabolic disease (i.e., higher vs. lower insulin resistance), no differences were observed in the NRs prevalence with regard to improved HOMA-IR or to anthropometric, cardiovascular, and muscle performance co-variables after 10 weeks of HIIT in sedentary adult women. This research demonstrates the protective effect of HIIT against cardiometabolic disease progression in a sedentary population. PMID:28729841

Hyperhoneycomb Iridate β -Li2IrO3 as a Platform for Kitaev Magnetism

NASA Astrophysics Data System (ADS)

Takayama, T.; Kato, A.; Dinnebier, R.; Nuss, J.; Kono, H.; Veiga, L. S. I.; Fabbris, G.; Haskel, D.; Takagi, H.

2015-02-01

A complex iridium oxide β -Li2IrO3 crystallizes in a hyperhoneycomb structure, a three-dimensional analogue of honeycomb lattice, and is found to be a spin-orbital Mott insulator with Jeff=1 /2 moment. Ir ions are connected to the three neighboring Ir ions via Ir -O2-Ir bonding planes, which very likely gives rise to bond-dependent ferromagnetic interactions between the Jeff=1 /2 moments, an essential ingredient of Kitaev model with a spin liquid ground state. Dominant ferromagnetic interaction between Jeff=1 /2 moments is indeed confirmed by the temperature dependence of magnetic susceptibility χ (T ) which shows a positive Curie-Weiss temperature θCW˜+40 K . A magnetic ordering with a very small entropy change, likely associated with a noncollinear arrangement of Jeff=1 /2 moments, is observed at Tc=38 K . With the application of magnetic field to the ordered state, a large moment of more than 0.35 μB/Ir is induced above 3 T, a substantially polarized Jeff=1 /2 state. We argue that the close proximity to ferromagnetism and the presence of large fluctuations evidence that the ground state of hyperhoneycomb β -Li2IrO3 is located in close proximity of a Kitaev spin liquid.

Ba3Fe1.56Ir1.44O9: A Polar Semiconducting Triple Perovskite with Near Room Temperature Magnetic Ordering.

PubMed

Ferreira, Timothy; Carone, Darren; Huon, Amanda; Herklotz, Andreas; Stoian, Sebastian A; Heald, Steve M; Morrison, Gregory; Smith, Mark D; Loye, Hans-Conrad Zur

2018-05-29

The crystal chemistry and magnetic properties for two triple perovskites, Ba 3 Fe 1.56 Ir 1.44 O 9 and Ba 3 NiIr 2 O 9 , grown as large, highly faceted single crystals from a molten strontium carbonate flux, are reported. Unlike the idealized A 3 MM 2 'O 9 hexagonal symmetry characteristic of most triple perovskites, including Ba 3 NiIr 2 O 9, Ba 3 Fe 1.56 Ir 1.44 O 9 possesses significant site-disorder, resulting in a noncentrosymmetric polar structure with trigonal symmetry. The valence of iron and iridium in the heavily distorted Fe/Ir sites was determined to be Fe(III) and Ir(V) by X-ray absorption near edge spectroscopy (XANES). Density functional theory calculations were conducted to understand the effect of the trigonal distortion on the local Fe(III)O 6 electronic structure, and the spin state of iron was determined to be S = 5/2 by Mössbauer spectroscopy. Conductivity measurements indicate thermally activated semiconducting behavior in the trigonal perovskite. Magnetic properties were measured and near room temperature magnetic ordering (T N = 270 K) was observed for Ba 3 Fe 1.56 Ir 1.44 O 9 .

Effect of Ir-Mn composition on exchange bias and thermal stability of spin valves with nano-oxide layers

NASA Astrophysics Data System (ADS)

Liu, Y. F.; Cai, J. W.; Lai, W. Y.; Yu, G. H.

2008-05-01

The Ir-Mn bottom-pinned spin valves with nano-oxide layers (NOLs), Ta /Ni81Fe19/Ir-Mn/Co90Fe10/NOL/Co90Fe10/Cu/Co90Fe10/NOL/Ta, were fabricated by dc magnetron sputtering. The magnetoresistance (MR), magnetization, and exchange bias have been studied as a function of Ir-Mn composition and annealing temperature. It was observed that the spin valves with the Ir-Mn layer containing relatively low Mn content (58.9-72.4at.% Mn) show the best thermal endurance. For these samples, the Mn diffusion is effectively hampered by the NOL with a large MR value of about 12.5% even after annealing at 300°C. On the other hand, the exchange bias field of the pinned CoFe layer shows a maximum at Mn content of about 72.4at.%, which is different from the widely adopted composition, Ir-80at.% Mn, optimized from the top-pinned NiFe /Ir-Mn system. Moreover, the blocking temperature of the Ir -Mn/CoFe system with 72.4at.% Mn is higher than that with 80.6at.% Mn. The present results suggest that the Ir -Mn/CoFe pinning system with Mn content at about 72% renders the most favorable exchange bias and the best thermal stability for the bottom-pinned specular spin valves.

Radiative and convective properties of 316L Stainless Steel fabricated using the Laser Engineered Net Shaping process

NASA Astrophysics Data System (ADS)

Knopp, Jonathan

Temperature evolution of metallic materials during the additive manufacturing process has direct influence in determining the materials microstructure and resultant characteristics. Through the power of Infrared (IR) thermography it is now possible to monitor thermal trends in a build structure, giving the power to adjust building parameters in real time. The IR camera views radiation in the IR wavelengths and determines temperature of an object by the amount of radiation emitted from the object in those wavelengths. Determining the amount of radiation emitted from the material, known as a materials emissivity, can be difficult in that emissivity is affected by both temperature and surface finish. It has been shown that the use of a micro-blackbody cavity can be used as an accurate reference temperature when the sample is held at thermal equilibrium. A micro-blackbody cavity was created in a sample of 316L Stainless Steel after being fabricated during using the Laser Engineered Net Shaping (LENS) process. Holding the sample at thermal equilibrium and using the micro-blackbody cavity as a reference and thermocouple as a second reference emissivity values were able to be obtained. IR thermography was also used to observe the manufacturing of these samples. When observing the IR thermography, patterns in the thermal history of the build were shown to be present as well as distinct cooling rates of the material. This information can be used to find true temperatures of 316L Stainless Steel during the LENS process for better control of desired material properties as well as future work in determining complete energy balance.

Silent and higher-order vibrations of C 60 and its compounds

NASA Astrophysics Data System (ADS)

Graja, Andrzej; Łapiński, Andrzej; Król, Sylwia

1997-02-01

We present rich IR spectra of solid samples of C 60 and its derivatives. Most of the IR lines are identified as the activated silent modes of the C 60 or second-order combination modes. The method of preparation of a complex of C 60 and chloro(triphenyl-phosphine) gold grown from toluene solution is described. Basic physical properties, in particular IR transmission of the single crystals of the complex, are studied as a function of temperature. Anomalies in the temperature dependences of the linewidths, their frequencies and intensities are observed and discussed.

μ SR and magnetometry study of superconducting 5% Pt-doped IrTe 2

DOE PAGES

Wilson, M. N.; Medina, T.; Munsie, T. J.; ...

2016-11-11

In this paper, we present magnetometry and muon spin rotation ( SR) measurements of the superconducting dichalcogenide Ir 0.95Pt 0.05Te 2. From both sets of measurements we calculate the penetration depth and thence superfluid density as a function of temperature. The temperature dependence of the superfluid densities from both sets of data indicate fully gapped superconductivity that can be fit to a conventional s-wave model and yield fitting parameters consistent with a BCS weak coupling superconductor. Finally, we therefore see no evidence for exotic superconductivity in Ir 0.95Pt 0.05Te 2.

μ SR and magnetometry study of superconducting 5% Pt-doped IrTe2

NASA Astrophysics Data System (ADS)

Wilson, M. N.; Medina, T.; Munsie, T. J.; Cheung, S. C.; Frandsen, B. A.; Liu, L.; Yan, J.; Mandrus, D.; Uemura, Y. J.; Luke, G. M.

2016-11-01

We present magnetometry and muon spin rotation (μ SR ) measurements of the superconducting dichalcogenide Ir0.95Pt0.05Te2 . From both sets of measurements, we calculate the penetration depth and thence superfluid density as a function of temperature. The temperature dependence of the superfluid densities from both sets of data indicate fully gapped superconductivity that can be fit to a conventional s -wave model and yield fitting parameters consistent with a BCS weak coupling superconductor. We therefore see no evidence for exotic superconductivity in Ir0.95Pt0.05Te2 .

Evaluation of waist-to-height ratio as a predictor of insulin resistance in non-diabetic obese individuals. A cross-sectional study.

PubMed

Jamar, Giovana; Almeida, Flávio Rossi de; Gagliardi, Antonio; Sobral, Marianna Ribeiro; Ping, Chao Tsai; Sperandio, Evandro; Romiti, Marcelo; Arantes, Rodolfo; Dourado, Victor Zuniga

2017-01-01

Insulin resistance (IR) and progressive pancreatic β-cell dysfunction have been identified as the two fundamental features in the pathogenesis of obesity and non-insulin-dependent diabetes mellitus. We aimed to investigate correlations between anthropometric indices of obesity and IR in non-diabetic obese individuals, and the cutoff value from receiver operating characteristic (ROC) curve analysis. Cross-sectional study conducted in a private clinic. We included obese individuals (body mass index, BMI ≥ 30 kg/m2) with no diabetes mellitus (fasting glucose levels ≤ 126 mg/dl). The participants were evaluated for the presence of cardiovascular risk factors and through anthropometric measurements and biochemical tests. Furthermore, IR was assessed indirectly using the homeostatic model assessment (HOMA)-IR and HOMA-β indexes. The area underthe curve (AUC) of the variables was compared.The sensitivity, specificity and cutoff of each variable for diagnosing IR were calculated. The most promising anthropometric parameters for indicating IR in non-diabetic obese individuals were waist-to-height ratio (WHtR), waist circumference (WC) and BMI. WHtR proved to be an independent predictor of IR, with risk increased by 0.53% in HOMA-IR, 5.3% in HOMA-β and 1.14% in insulin. For HOMA-IR, WHtR had the highest AUC value (0.98), followed by WC (0.93) and BMI (0.81). For HOMA-β, WHtR also had the highest AUC value (0.83), followed by WC (0.75) and BMI (0.73).The optimal WHtR cutoff was 0.65 for HOMA-IR and 0.67 for HOMA-β. Among anthropometric obesity indicators, WHtR was most closely associated with occurrences of IR and predicted the onset of diabetes in obese individuals.

Precipitation, Convective Clouds, and Their Connections With Tropical Cyclone Intensity and Intensity Change

NASA Astrophysics Data System (ADS)

Ruan, Zhenxin; Wu, Qiaoyan

2018-01-01

In this paper, satellite-based precipitation, clouds with infrared (IR) brightness temperature (BT), and tropical cyclone (TC) data from 2000 to 2015 are used to explore the relationship between precipitation, convective cloud, and TC intensity change in the Western North Pacific Ocean. An IR BT of 208 K was chosen as a threshold for deep convection based on different diurnal cycles of IR BT. More precipitation and colder clouds with 208 K < IR BT < 240 K are found as storms intensify, while TC 24 h future intensity change is closely connected with very deep convective clouds with IR BT < 208 K. Intensifying TCs follow the occurrence of colder clouds with IR BT < 208 K with greater areal extents. As an indicator of very deep convective clouds, IR BT < 208 K is suggested to be a good predictor of TC intensity change. Based upon the 16 year analysis in the western North Pacific, TCs under the conditions that the mean temperature of very deep convective clouds is less than 201 K, and the coverage of this type of clouds is more than 27.4% within a radius of 300 km of the TC center, will more likely undergo rapid intensification after 24 h.

Electrical Energy Harvesting from Thermal Energy with Converged Infrared Light

NASA Astrophysics Data System (ADS)

Goh, S. Y.; Kok, S. L.

2017-06-01

Photovoltaics (PV) cell is a common energy harvester that had been used to harvest solar energy and convert it into electrical energy. However, the vast energy from the spectrum of sunlight is not fully harvested. Therefore, thermoelectric (TE) module that harvest electrical energy from heat is being proposed in this paper. Generally, the part of the sunlight spectrum that induce heat is in the spectrum band of infrared (IR). For the experimental set-up in this paper, infrared (IR) light bulb was being used to simulate the IR spectrum band of the sunlight. In order to maximize the heat energy collection, a convex lens was being used to converge the IR light and therefore focused the heat on an aluminium sheet and heat sink which was placed on top of the hot side of the TE module. The distance between convex lens and IR light bulb is varying in between 10cm and 55cm and the reading was taken at an interval of 5cm. Firstly, the temperature of the IR light and converged IR light were recorded and plotted in graph. The graph showed that the temperature of the converged IR light bulb is higher than the IR light bulb. Lastly, the voltage and power output of the TE module with different heat source was compared. The output voltage and power of the TE module increased inverse proportional to the distance between IR light bulb and TE module.

Dual time-resolved temperature-jump fluorescence and infrared spectroscopy for the study of fast protein dynamics.

PubMed

Davis, Caitlin M; Reddish, Michael J; Dyer, R Brian

2017-05-05

Time-resolved temperature-jump (T-jump) coupled with fluorescence and infrared (IR) spectroscopy is a powerful technique for monitoring protein dynamics. Although IR spectroscopy of the polypeptide amide I mode is more technically challenging, it offers complementary information because it directly probes changes in the protein backbone, whereas, fluorescence spectroscopy is sensitive to the environment of specific side chains. With the advent of widely tunable quantum cascade lasers (QCL) it is possible to efficiently probe multiple IR frequencies with high sensitivity and reproducibility. Here we describe a dual time-resolved T-jump fluorescence and IR spectrometer and its application to study protein folding dynamics. A Q-switched Ho:YAG laser provides the T-jump source for both time-resolved IR and fluorescence spectroscopy, which are probed by a QCL and Ti:Sapphire laser, respectively. The Ho:YAG laser simultaneously pumps the time-resolved IR and fluorescence spectrometers. The instrument has high sensitivity, with an IR absorbance detection limit of <0.2mOD and a fluorescence sensitivity of 2% of the overall fluorescence intensity. Using a computer controlled QCL to rapidly tune the IR frequency it is possible to create a T-jump induced difference spectrum from 50ns to 0.5ms. This study demonstrates the power of the dual time-resolved T-jump fluorescence and IR spectroscopy to resolve complex folding mechanisms by complementary IR absorbance and fluorescence measurements of protein dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

Dual time-resolved temperature-jump fluorescence and infrared spectroscopy for the study of fast protein dynamics

NASA Astrophysics Data System (ADS)

Davis, Caitlin M.; Reddish, Michael J.; Dyer, R. Brian

2017-05-01

Time-resolved temperature-jump (T-jump) coupled with fluorescence and infrared (IR) spectroscopy is a powerful technique for monitoring protein dynamics. Although IR spectroscopy of the polypeptide amide I mode is more technically challenging, it offers complementary information because it directly probes changes in the protein backbone, whereas, fluorescence spectroscopy is sensitive to the environment of specific side chains. With the advent of widely tunable quantum cascade lasers (QCL) it is possible to efficiently probe multiple IR frequencies with high sensitivity and reproducibility. Here we describe a dual time-resolved T-jump fluorescence and IR spectrometer and its application to study protein folding dynamics. A Q-switched Ho:YAG laser provides the T-jump source for both time-resolved IR and fluorescence spectroscopy, which are probed by a QCL and Ti:Sapphire laser, respectively. The Ho:YAG laser simultaneously pumps the time-resolved IR and fluorescence spectrometers. The instrument has high sensitivity, with an IR absorbance detection limit of < 0.2 mOD and a fluorescence sensitivity of 2% of the overall fluorescence intensity. Using a computer controlled QCL to rapidly tune the IR frequency it is possible to create a T-jump induced difference spectrum from 50 ns to 0.5 ms. This study demonstrates the power of the dual time-resolved T-jump fluorescence and IR spectroscopy to resolve complex folding mechanisms by complementary IR absorbance and fluorescence measurements of protein dynamics.

Triglyceride Glucose-Body Mass Index Is a Simple and Clinically Useful Surrogate Marker for Insulin Resistance in Nondiabetic Individuals.

PubMed

Er, Leay-Kiaw; Wu, Semon; Chou, Hsin-Hua; Hsu, Lung-An; Teng, Ming-Sheng; Sun, Yu-Chen; Ko, Yu-Lin

2016-01-01

Insulin resistance (IR) and the consequences of compensatory hyperinsulinemia are pathogenic factors for a set of metabolic abnormalities, which contribute to the development of diabetes mellitus and cardiovascular diseases. We compared traditional lipid levels and ratios and combined them with fasting plasma glucose (FPG) levels or adiposity status for determining their efficiency as independent risk factors for IR. We enrolled 511 Taiwanese individuals for the analysis. The clinical usefulness of various parameters--such as traditional lipid levels and ratios; visceral adiposity indicators, visceral adiposity index (VAI), and lipid accumulation product (LAP); the product of triglyceride (TG) and FPG (the TyG index); TyG with adiposity status (TyG-body mass index [BMI]) and TyG-waist circumference index [WC]); and adipokine levels and ratios--was analyzed to identify IR. For all lipid ratios, the TG/high-density lipoprotein cholesterol (HDL-C) ratio had the highest additional percentage of variation in the homeostasis model assessment of insulin resistance (HOMA-IR; 7.0% in total); for all variables of interest, TyG-BMI and leptin-adiponectin ratio (LAR) were strongly associated with HOMA-IR, with 16.6% and 23.2% of variability, respectively. A logistic regression analysis revealed similar patterns. A receiver operating characteristic (ROC) curve analysis indicated that TG/HDL-C was a more efficient IR discriminator than other lipid variables or ratios. The area under the ROC curve (AUC) for VAI (0.734) and TyG (0.708) was larger than that for TG/HDL-C (0.707). TyG-BMI and LAR had the largest AUC (0.801 and 0.801, respectively). TyG-BMI is a simple, powerful, and clinically useful surrogate marker for early identification of IR.

Triglyceride Glucose-Body Mass Index Is a Simple and Clinically Useful Surrogate Marker for Insulin Resistance in Nondiabetic Individuals

PubMed Central

Er, Leay-Kiaw; Wu, Semon; Chou, Hsin-Hua; Hsu, Lung-An; Teng, Ming-Sheng; Sun, Yu-Chen; Ko, Yu-Lin

2016-01-01

Background Insulin resistance (IR) and the consequences of compensatory hyperinsulinemia are pathogenic factors for a set of metabolic abnormalities, which contribute to the development of diabetes mellitus and cardiovascular diseases. We compared traditional lipid levels and ratios and combined them with fasting plasma glucose (FPG) levels or adiposity status for determining their efficiency as independent risk factors for IR. Methods We enrolled 511 Taiwanese individuals for the analysis. The clinical usefulness of various parameters—such as traditional lipid levels and ratios; visceral adiposity indicators, visceral adiposity index (VAI), and lipid accumulation product (LAP); the product of triglyceride (TG) and FPG (the TyG index); TyG with adiposity status (TyG-body mass index [BMI]) and TyG-waist circumference index [WC]); and adipokine levels and ratios—was analyzed to identify IR. Results For all lipid ratios, the TG/high-density lipoprotein cholesterol (HDL-C) ratio had the highest additional percentage of variation in the homeostasis model assessment of insulin resistance (HOMA-IR; 7.0% in total); for all variables of interest, TyG-BMI and leptin-adiponectin ratio (LAR) were strongly associated with HOMA-IR, with 16.6% and 23.2% of variability, respectively. A logistic regression analysis revealed similar patterns. A receiver operating characteristic (ROC) curve analysis indicated that TG/HDL-C was a more efficient IR discriminator than other lipid variables or ratios. The area under the ROC curve (AUC) for VAI (0.734) and TyG (0.708) was larger than that for TG/HDL-C (0.707). TyG-BMI and LAR had the largest AUC (0.801 and 0.801, respectively). Conclusion TyG-BMI is a simple, powerful, and clinically useful surrogate marker for early identification of IR. PMID:26930652

Examining Rotational Variability in the Upper Tropospheres and Lower Stratospheres of Uranus and Neptune from Herschel PACS OT1 Observations: Implications for the Stability of Temperature and Compositional Structure

NASA Astrophysics Data System (ADS)

Orton, G.; Feuchtgruber, H.; Fletcher, L.; Lellouch, E.; Moreno, R.; Billebaud, F.; Cavalie, T.; Decin, L.; Dobreijecvic, M.; Encrenaz, T.; Hartogh, P.; Jarchow, C.; Lara, L. M.; Liu, J.

2012-04-01

The power of high-resolution submillimeter spectroscopy of Uranus and Neptune was put to use to survey the rotational variability of stratospheric and tropospheric constituents of their atmospheres. These observations were motivated by the surprising discovery of as much as 12% rotational variability of emission from stratospheric constituents in the atmosphere of Uranus by the Spitzer Infrared Spectrometer and the detection of spatial variability in thermal images of Neptune's stratospheric emission (Orton et al. 2007, Astron. & Astrophys 473, L3). Our observing program consisted of three separate sequences of observations to look at the strongest lines of H2O in the high-resolution PACS spectra of both planets, whose upwelling radiance emerges from the same vertical region as the Spitzer IRS observations of Uranus and ground-based images of Neptune, and the strongest line of CH4 in the PACS spectrum of Neptune. We omitted measurements of CH4 lines in Uranus, which are almost non-detectable. We added the strongest HD line in Uranus to measure variability of tropospheric temperatures that could modulate stratospheric CH4 abundances through local cold-trapping and the strongest two HD lines in Neptune (Lellouch et al. 2010, Astron. & Astrophys. 518, L152) that determine both the tropopause temperature to limit local cold-trapping efficacy and the lower stratospheric temperature, to help differentiate between longitudinal variability of stratospheric H2O and CH4 abundances vs. temperatures. These were repeated over the 17-hour interval that is common to the equatorial rotation periods of both Uranus and Neptune. Although these lines had already been observed in Uranus and Neptune by PACS, no repeat measurements had ever been made to determine longitudinal variability. The observations were consistent with previous measurements, but no significant rotational variability was detected. It is possible that the absence of rotational variability in the HD and CH4 lines is because variability is confined to very low pressures, e.g. much lower than a microbar. However, the absence of variable emission from high-altitude exogenic H2O vapor is harder to explain, unless the variability seen in Uranus by Spitzer and in Neptune from the VLT, is not the result of variations in temperature by in the hydrocarbon abundances. Alternatively, the stratospheres of both planets are variable in time. The cause of such variability is unknown, but spatially confined outbursts have been detected in the visible and near infrared, and they may have as much influence on the stratosphere of Uranus as the great springtime storm in Saturn's northern hemisphere, creating a strong, localized "beacon" of thermal radiation (cf. Fletcher et al. 2011, Science, 332,1413) that could dominate the emission observed over the hemisphere.

Low-speed flowfield characterization by infrared measurements of surface temperatures

NASA Technical Reports Server (NTRS)

Gartenberg, E.; Roberts, A. S., Jr.; Mcree, G. J.

1989-01-01

An experimental program was aimed at identifying areas in low speed aerodynamic research where infrared imaging systems can make significant contributions. Implementing a new technique, a long electrically heated wire was placed across a laminar jet. By measuring the temperature distribution along the wire with the IR imaging camera, the flow behavior was identified. Furthermore, using Nusselt number correlations, the velocity distribution could be deduced. The same approach was used to survey wakes behind cylinders in a wind-tunnel. This method is suited to investigate flows with position dependent velocities, e.g., boundary layers, confined flows, jets, wakes, and shear layers. It was found that the IR imaging camera cannot accurately track high gradient temperature fields. A correlation procedure was devised to account for this limitation. Other wind-tunnel experiments included tracking the development of the laminar boundary layer over a warmed flat plate by measuring the chordwise temperature distribution. This technique was applied also to the flow downstream from a rearward facing step. Finally, the IR imaging system was used to study boundary layer behavior over an airfoil at angles of attack from zero up to separation. The results were confirmed with tufts observable both visually and with the IR imaging camera.

A one-dimensional free energy surface does not account for two-probe folding kinetics of protein alpha(3)D.

PubMed

Liu, Feng; Dumont, Charles; Zhu, Yongjin; DeGrado, William F; Gai, Feng; Gruebele, Martin

2009-02-14

We present fluorescence-detected measurements of the temperature-jump relaxation kinetics of the designed three-helix bundle protein alpha(3)D taken under solvent conditions identical to previous infrared-detected kinetics. The fluorescence-detected rate is similar to the IR-detected rate only at the lowest temperature where we could measure it (326 K). The fluorescence-detected rate decreases by a factor of 3 over the 326-344 K temperature range, whereas the IR-detected rate remains nearly constant over the same range. To investigate this probe dependence, we tested an extensive set of physically reasonable one-dimensional (1D) free energy surfaces by Langevin dynamics simulation. The simulations included coordinate- and temperature-dependent roughness, diffusion coefficients, and IR/fluorescence spectroscopic signatures. None of these can reproduce the IR and fluorescence data simultaneously, forcing us to the conclusion that a 1D free energy surface cannot accurately describe the folding of alpha(3)D. This supports the hypothesis that alpha(3)D has a multidimensional free energy surface conducive to downhill folding at 326 K, and that it is already an incipient downhill folder with probe-dependent kinetics near its melting point.

High resolution temperature mapping of gas turbine combustor simulator exhaust with femtosecond laser induced fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Walker, Robert B.; Yun, Sangsig; Ding, Huimin; Charbonneau, Michel; Coulas, David; Lu, Ping; Mihailov, Stephen J.; Ramachandran, Nanthan

2017-04-01

Femtosecond infrared (fs-IR) laser written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent in advanced gas turbine engines under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper discusses fabrication and deployment of several fs-IR written FBG arrays, for monitoring exhaust temperature gradients of a gas turbine combustor simulator. Results include: contour plots of measured temperature gradients, contrast with thermocouple data.

Simultaneous Temperature and Velocity Measurements in a Large-Scale, Supersonic, Heated Jet

NASA Technical Reports Server (NTRS)

Danehy, P. M.; Magnotti, G.; Bivolaru, D.; Tedder, S.; Cutler, A. D.

2008-01-01

Two laser-based measurement techniques have been used to characterize an axisymmetric, combustion-heated supersonic jet issuing into static room air. The dual-pump coherent anti-Stokes Raman spectroscopy (CARS) measurement technique measured temperature and concentration while the interferometric Rayleigh scattering (IRS) method simultaneously measured two components of velocity. This paper reports a preliminary analysis of CARS-IRS temperature and velocity measurements from selected measurement locations. The temperature measurements show that the temperature along the jet axis remains constant while dropping off radially. The velocity measurements show that the nozzle exit velocity fluctuations are about 3% of the maximum velocity in the flow.

Synthesis and properties of greenish-blue-emitting iridium dendrimers with N-phenylcarbazole-based polyether dendrons by a post-dendronization route.

PubMed

Wang, Yang; Wang, Shumeng; Shao, Shiyang; Ding, Junqiao; Wang, Lixiang; Jing, Xiabin; Wang, Fosong

2015-01-21

A series of solution processible greenish-blue-emitting Ir dendrimers with polyether dendrons that consist of N-phenylcarbazole (NPC) are developed via a convenient post-dendronization method. It involves two steps: (i) the successful preparation of a reactive Ir core, namely m-HO-dfppyIr, only when the hydroxyl group is located at the meta position relative to the N atom in the C^N ligand so as to eliminate the possible resonance structure between enol and keto; and (ii) the subsequent functionalization with NPC-based polyether dendrons to afford the first, second and third generation Ir dendrimers (Ir-G1B, Ir-G2B and Ir-G3B) with ease and high yields over 60%. All these dendritic complexes possess good thermal stability with decomposition temperatures higher than 380 °C and glass transition temperatures higher than 200 °C. In addition, with the growing generation number, the intermolecular interactions between emissive Ir cores are expected to be effectively inhibited to avoid the luminescence quenching, which is confirmed from the blue-shifted emission peak and the enhanced lifetime of Ir-G3B in the solid state. As a result, on going from Ir-G1B to Ir-G3B, the maximum luminous efficiency rises upward from 4.7 to 9.2 cd A(-1) for nondoped electrophosphorescent devices. Further optimization by doping them into a dendritic H2 host leads to the improved luminous efficiencies as high as 20.0-25.2 cd A(-1).

Two-Magnon Raman Scattering and Pseudospin-Lattice Interactions in Sr_{2}IrO_{4} and Sr_{3}Ir_{2}O_{7}.

PubMed

Gretarsson, H; Sung, N H; Höppner, M; Kim, B J; Keimer, B; Le Tacon, M

2016-04-01

We have used Raman scattering to investigate the magnetic excitations and lattice dynamics in the prototypical spin-orbit Mott insulators Sr_{2}IrO_{4} and Sr_{3}Ir_{2}O_{7}. Both compounds exhibit pronounced two-magnon Raman scattering features with different energies, line shapes, and temperature dependencies, which in part reflect the different influence of long-range frustrating exchange interactions. Additionally, we find strong Fano asymmetries in the line shapes of low-energy phonon modes in both compounds, which disappear upon cooling below the antiferromagnetic ordering temperatures. These unusual phonon anomalies indicate that the spin-orbit coupling in Mott-insulating iridates is not sufficiently strong to quench the orbital dynamics in the paramagnetic state.

Mesoporous silica nanoparticle supported PdIr bimetal catalyst for selective hydrogenation, and the significant promotional effect of Ir

NASA Astrophysics Data System (ADS)

Yang, Hui; Huang, Chao; Yang, Fan; Yang, Xu; Du, Li; Liao, Shijun

2015-12-01

A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (NIr/NPd = 0.1), the activity of PdIr0.1/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd-Ir electronic interaction caused by the addition of Ir.

Testing of Wrought Iridium/Chemical Vapor Deposition Rhenium Rocket

NASA Technical Reports Server (NTRS)

Reed, Brian D.; Schneider, Steven J.

1996-01-01

A 22-N class, iridium/rhenium (Ir/Re) rocket chamber, composed of a thick (418 miocrometer) wrought iridium (Ir) liner and a rhenium substrate deposited via chemical vapor deposition, was tested over an extended period on gaseous oxygen/gaseous hydrogen (GO2/GH2) propellants. The test conditions were designed to produce species concentrations similar to those expected in an Earth-storable propellant combustion environment. Temperatures attained in testing were significantly higher than those expected with Earth-storable propellants, both because of the inherently higher combustion temperature of GO2/GH2 propellants and because the exterior surface of the rocket was not treated with a high-emissivity coating that would be applied to flight class rockets. Thus the test conditions were thought to represent a more severe case than for typical operational applications. The chamber successfully completed testing (over 11 hr accumulated in 44 firings), and post-test inspections showed little degradation of the Ir liner. The results indicate that use of a thick, wrought Ir liner is a viable alternative to the Ir coatings currently used for Ir/Re rockets.

GASPS Photometry of the Tucana-Horologium Association

NASA Technical Reports Server (NTRS)

Roberge, Donaldson J.; Roberge, Aki

2010-01-01

The GASPS Open Time Key Programme on Herschel represents a new opportunity to sensitively probe protoplanetary and debris disks at far-IR wavelengths. We present preliminary PACS 70 and 160 micron photometry of eighteen stars in the 30 Myr-old Tucana-Horologium association. Of these eighteen, eight were detected in the 70 micron band. Four of these eight were also detected in the 160 micron band. We constructed SEDs for these systems using optical data from Hipparcos (B and V), near-IR data from 2MASS (J, H, and K), mid-IR data from IRAS and Spitzer MIPS (12 and 24 microns, respectively), and the new far-IR data from PACS. For the stars showing IR excess emission, we fit simple single-temperature blackbody curves to the IR excess in order to determine the rough dust abundances and temperatures. Dust observations at these wavelengths will also be important for comparison with upcoming Herschel PACS spectra that will search for gas in the disks. Our goal is to determine or limit the ever-allusive gas-to-dust ratio for these disk systems.

External cavity-quantum cascade laser infrared spectroscopy for secondary structure analysis of proteins at low concentrations

PubMed Central

Schwaighofer, Andreas; Alcaráz, Mirta R.; Araman, Can; Goicoechea, Héctor; Lendl, Bernhard

2016-01-01

Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy are analytical techniques employed for the analysis of protein secondary structure. The use of CD spectroscopy is limited to low protein concentrations (<2 mg ml−1), while FTIR spectroscopy is commonly used in a higher concentration range (>5 mg ml−1). Here we introduce a quantum cascade laser (QCL)-based IR transmission setup for analysis of protein and polypeptide secondary structure at concentrations as low as 0.25 mg ml−1 in deuterated buffer solution. We present dynamic QCL-IR spectra of the temperature-induced α-helix to β-sheet transition of poly-L-lysine. The concentration dependence of the α-β transition temperature between 0.25 and 10 mg ml−1 was investigated by QCL-IR, FTIR and CD spectroscopy. By using QCL-IR spectroscopy it is possible to perform IR spectroscopic analysis in the same concentration range as CD spectroscopy, thus enabling a combined analysis of biomolecules secondary structure by CD and IR spectroscopy. PMID:27633337

Hybridized orbital states in spin-orbit coupled 3 d -5 d double perovskites studied by x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Min-Cheol; Lee, Sanghyun; Won, C. J.; Lee, K. D.; Hur, N.; Chen, Jeng-Lung; Cho, Deok-Yong; Noh, T. W.

2018-03-01

We investigated the orbital hybridization mechanism in 3 d -5 d double perovskites (DPs) of La2CoIrO6 and La2CoPtO6 using x-ray absorption spectroscopy. It is clearly evidenced by O K -edge and Co K -edge x-ray absorption spectra that the Co 3 d orbitals hybridize not only with the half-filled Ir/Pt jeff states but also with the fully empty (unpolarized) Ir/Pt eg states in both DPs. The Co 3 d eg-Ir 5 d eg hybridization cannot contribute to the ferrimagnetic long-range order in La2CoIrO6 established by spin-selective Co 3 d t2 g-Ir 5 d jeff hybridization through the intermediate oxygen p state but could serve as an origin of paramagnetism. The strengths of such orbital hybridizations were found to be almost invariant to temperature, even far above the Curie temperature, implying persistent paramagnetism against the antiferromagnetic ordering in the spin-orbit entangled 3 d -5 d DPs.

External cavity-quantum cascade laser infrared spectroscopy for secondary structure analysis of proteins at low concentrations.

PubMed

Schwaighofer, Andreas; Alcaráz, Mirta R; Araman, Can; Goicoechea, Héctor; Lendl, Bernhard

2016-09-16

Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy are analytical techniques employed for the analysis of protein secondary structure. The use of CD spectroscopy is limited to low protein concentrations (<2 mg ml(-1)), while FTIR spectroscopy is commonly used in a higher concentration range (>5 mg ml(-1)). Here we introduce a quantum cascade laser (QCL)-based IR transmission setup for analysis of protein and polypeptide secondary structure at concentrations as low as 0.25 mg ml(-1) in deuterated buffer solution. We present dynamic QCL-IR spectra of the temperature-induced α-helix to β-sheet transition of poly-L-lysine. The concentration dependence of the α-β transition temperature between 0.25 and 10 mg ml(-1) was investigated by QCL-IR, FTIR and CD spectroscopy. By using QCL-IR spectroscopy it is possible to perform IR spectroscopic analysis in the same concentration range as CD spectroscopy, thus enabling a combined analysis of biomolecules secondary structure by CD and IR spectroscopy.

Twisted Hubbard model for Sr2IrO4: magnetism and possible high temperature superconductivity.

PubMed

Wang, Fa; Senthil, T

2011-04-01

Sr(2)IrO(4) has been suggested as a Mott insulator from a single J(eff)=1/2 band, similar to the cuprates. However, this picture is complicated by the measured large magnetic anisotropy and ferromagnetism. Based on a careful mapping to the J(eff)=1/2 (pseudospin-1/2) space, we propose that the low energy electronic structure of Sr(2)IrO(4) can indeed be described by a SU(2) invariant pseudospin-1/2 Hubbard model very similar to that of the cuprates, but with a twisted coupling to an external magnetic field (a g tensor with a staggered antisymmetric component). This perspective naturally explains the magnetic properties of Sr(2)IrO(4). We also derive several simple facts based on this mapping and the known results about the Hubbard model and the cuprates, which may be tested in future experiments on Sr(2)IrO(4). In particular, we propose that (electron-)doping Sr(2)IrO(4) can potentially realize high-temperature superconductivity. © 2011 American Physical Society

Integrating Omics and Alternative Splicing Reveals Insights into Grape Response to High Temperature1[OPEN

PubMed Central

Jiang, Jianfu; Liu, Xinna; Liu, Guotian; Li, Shaohua

2017-01-01

Heat stress is one of the primary abiotic stresses that limit crop production. Grape (Vitis vinifera) is a cultivated fruit with high economic value throughout the world, with its growth and development often influenced by high temperature. Alternative splicing (AS) is a widespread phenomenon increasing transcriptome and proteome diversity. We conducted high-temperature treatments (35°C, 40°C, and 45°C) on grapevines and assessed transcriptomic (especially AS) and proteomic changes in leaves. We found that nearly 70% of the genes were alternatively spliced under high temperature. Intron retention (IR), exon skipping, and alternative donor/acceptor sites were markedly induced under different high temperatures. Among all differential AS events, IR was the most abundant up- and down-regulated event. Moreover, the occurrence frequency of IR events at 40°C and 45°C was far higher than at 35°C. These results indicated that AS, especially IR, is an important posttranscriptional regulatory event during grape leaf responses to high temperature. Proteomic analysis showed that protein levels of the RNA-binding proteins SR45, SR30, and SR34 and the nuclear ribonucleic protein U1A gradually rose as ambient temperature increased, which revealed a reason why AS events occurred more frequently under high temperature. After integrating transcriptomic and proteomic data, we found that heat shock proteins and some important transcription factors such as MULTIPROTEIN BRIDGING FACTOR1c and HEAT SHOCK TRANSCRIPTION FACTOR A2 were involved mainly in heat tolerance in grape through up-regulating transcriptional (especially modulated by AS) and translational levels. To our knowledge, these results provide the first evidence for grape leaf responses to high temperature at simultaneous transcriptional, posttranscriptional, and translational levels. PMID:28049741

Integrating Omics and Alternative Splicing Reveals Insights into Grape Response to High Temperature.

PubMed

Jiang, Jianfu; Liu, Xinna; Liu, Chonghuai; Liu, Guotian; Li, Shaohua; Wang, Lijun

2017-02-01

Heat stress is one of the primary abiotic stresses that limit crop production. Grape (Vitis vinifera) is a cultivated fruit with high economic value throughout the world, with its growth and development often influenced by high temperature. Alternative splicing (AS) is a widespread phenomenon increasing transcriptome and proteome diversity. We conducted high-temperature treatments (35°C, 40°C, and 45°C) on grapevines and assessed transcriptomic (especially AS) and proteomic changes in leaves. We found that nearly 70% of the genes were alternatively spliced under high temperature. Intron retention (IR), exon skipping, and alternative donor/acceptor sites were markedly induced under different high temperatures. Among all differential AS events, IR was the most abundant up- and down-regulated event. Moreover, the occurrence frequency of IR events at 40°C and 45°C was far higher than at 35°C. These results indicated that AS, especially IR, is an important posttranscriptional regulatory event during grape leaf responses to high temperature. Proteomic analysis showed that protein levels of the RNA-binding proteins SR45, SR30, and SR34 and the nuclear ribonucleic protein U1A gradually rose as ambient temperature increased, which revealed a reason why AS events occurred more frequently under high temperature. After integrating transcriptomic and proteomic data, we found that heat shock proteins and some important transcription factors such as MULTIPROTEIN BRIDGING FACTOR1c and HEAT SHOCK TRANSCRIPTION FACTOR A2 were involved mainly in heat tolerance in grape through up-regulating transcriptional (especially modulated by AS) and translational levels. To our knowledge, these results provide the first evidence for grape leaf responses to high temperature at simultaneous transcriptional, posttranscriptional, and translational levels. © 2017 American Society of Plant Biologists. All Rights Reserved.

Optimization of process variables by response surface methodology for malachite green dye removal using lime peel activated carbon

NASA Astrophysics Data System (ADS)

Ahmad, Mohd Azmier; Afandi, Nur Syahidah; Bello, Olugbenga Solomon

2017-05-01

This study investigates the adsorptive removal of malachite green (MG) dye from aqueous solutions using chemically modified lime-peel-based activated carbon (LPAC). The adsorbent prepared was characterized using FTIR, SEM, Proximate analysis and BET techniques, respectively. Central composite design (CCD) in response surface methodology (RSM) was used to optimize the adsorption process. The effects of three variables: activation temperature, activation time and chemical impregnation ratio (IR) using KOH and their effects on percentage of dye removal and LPAC yield were investigated. Based on CCD design, quadratic models and two factor interactions (2FI) were developed correlating the adsorption variables to the two responses. Analysis of variance (ANOVA) was used to judge the adequacy of the model. The optimum conditions of MG dye removal using LPAC are: activation temperature (796 °C), activation time (1.0 h) and impregnation ratio (2.6), respectively. The percentage of MG dye removal obtained was 94.68 % resulting in 17.88 % LPAC yield. The percentage of error between predicted and experimental results for the removal of MG dye is 0.4 %. Model prediction was in good agreement with experimental results and LPAC was found to be effective in removing MG dye from aqueous solution.

Vibrational spectra (FT-IR, Raman and MI-IR) of α- and β-alanine

NASA Astrophysics Data System (ADS)

Rosado, Mário Túlio S.; Duarte, Maria Leonor R. S.; Fausto, Rui

1997-06-01

The vibrational spectra of α- and β-alaine molecules in both their zwitterionic and neutral forms are studied by FT-IR, Raman and MI-IR spectroscopy. Together with results from theoretical SCF-MO ab initio calculations, the spectroscopic data obtained under the various experimental conditions used in this study (crystalline phase; low temperature matrix isolated molecules) enable to undertake a detailed assignment of the vibrational spectra of the studied compounds.

Clinical usefulness of lipid ratios, visceral adiposity indicators, and the triglycerides and glucose index as risk markers of insulin resistance.

PubMed

Du, Tingting; Yuan, Gang; Zhang, Muxun; Zhou, Xinrong; Sun, Xingxing; Yu, Xuefeng

2014-10-20

To directly compare traditional lipid ratios (total cholesterol [TC]/high density lipoprotein cholesterol [HDL-C], non-HDL-C/HDL-C, low density lipoprotein cholesterol [LDL-C]/HDL-C, and triglycerides [TG]/HDL-C), apolipoprotein B (apoB)/apolipoprotein A-I (apoA-I) ratio, visceral adiposity index (VAI), lipid accumulation product (LAP), and the product of TG and fasting glucose (TyG) for strength and independence as risk factors for insulin resistance (IR). We conducted a cross-sectional analysis of 7629 Chinese adults using data from the China Health and Nutrition Survey 2009. For all lipid ratios (traditional lipid ratios and apoB/apoA-I), among both sexes, TG/HDL-C explained the most additional percentage of variation in HOMA-IR (2.9% in men, and 2.3% in women); for all variables of interest, the variability in HOMA-IR explained by VAI and TG/HDL-C were comparable; TyG had the most significant association with HOMA-IR, which explained 9.1% for men and 7.8% for women of the variability in HOMA-IR. Logistic regression analysis showed the similar patterns. Receiver operating characteristic (ROC) curve analysis showed that, among both sexes, TG/HDL-C was a better discriminator of IR than apoB/apoA-I; the area under the ROC curve (AUC) for VAI (0.695 in men and 0.682 in women) was greater than that for TG/HDL-C (AUC 0.665 in men and 0.664 in women); TyG presented the greatest value of AUC (0.709 in men and 0.711 in women). The apoB/apoA-I performs no better than any of the traditional lipid ratios in correlating with IR. The TG/HDL-C, VAI and TyG are better markers for early identification of IR individuals.

Microstructure evolution of the Ir-inserted Ni silicides with additional annealing

NASA Astrophysics Data System (ADS)

Yoon, Kijeong; Song, Ohsung

2009-02-01

Thermally-evaporated 10 nm-Ni/1 nm-Ir/(poly)Si structures were fabricated in order to investigate the thermal stability of Ir-inserted nickel silicide after additional annealing. The silicide samples underwent rapid thermal annealing at 300 ° C to 1200 ° C for 40 s, followed by 30 min annealing at the given RTA temperatures. Silicides suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates, mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution x-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively. Transmission electron microscope and scanning probe microscope were used to determine the cross-section structure and surface roughness. The silicide, which formed on single crystal silicon substrate with surface agglomeration after additional annealing, could defer the transformation of Ni(Ir)Si to Ni(Ir)Si2 and was stable at temperatures up to 1200 °C. Moreover, the silicide thickness doubled. There were no outstanding changes in the silicide thickness on polycrystalline silicon. However, after additional annealing, the silicon-silicide mixing became serious and showed high resistance at temperatures >700 °C. Auger depth profiling confirmed the increased thickness of the silicide layers after additional annealing without a change in composition. For a single crystal silicon substrate, the sheet resistance increased slightly due to the significant increases in surface roughness caused by surface agglomeration after additional annealing. Otherwise, there were almost no changes in surface roughness on the polycrystalline silicon substrate. The Ir-inserted nickel monosilicide was able to maintain a low resistance in a wide temperature range and is considered suitable for the nano-thick silicide process.

External-Cavity Quantum Cascade Laser Spectroscopy for Mid-IR Transmission Measurements of Proteins in Aqueous Solution.

PubMed

Alcaráz, Mirta R; Schwaighofer, Andreas; Kristament, Christian; Ramer, Georg; Brandstetter, Markus; Goicoechea, Héctor; Lendl, Bernhard

2015-07-07

In this work, we report mid-IR transmission measurements of the protein amide I band in aqueous solution at large optical paths. A tunable external-cavity quantum cascade laser (EC-QCL) operated in pulsed mode at room temperature allowed one to apply a path length of up to 38 μm, which is four times larger than that applicable with conventional FT-IR spectrometers. To minimize temperature-induced variations caused by background absorption of the ν2-vibration of water (HOH-bending) overlapping with the amide I region, a highly stable temperature control unit with relative temperature stability within 0.005 °C was developed. An advanced data processing protocol was established to overcome fluctuations in the fine structure of the emission curve that are inherent to the employed EC-QCL due to its mechanical instabilities. To allow for wavenumber accuracy, a spectral calibration method has been elaborated to reference the acquired IR spectra to the absolute positions of the water vapor absorption bands. Employing this setup, characteristic spectral features of five well-studied proteins exhibiting different secondary structures could be measured at concentrations as low as 2.5 mg mL(-1). This concentration range could previously only be accessed by IR measurements in D2O. Mathematical evaluation of the spectral overlap and comparison of second derivative spectra confirm excellent agreement of the QCL transmission measurements with protein spectra acquired by FT-IR spectroscopy. This proves the potential of the applied setup to monitor secondary structure changes of proteins in aqueous solution at extended optical path lengths, which allow experiments in flow through configuration.

Infrared Imaging of Nitric Oxide-Mediated Blood Flow in Human Sickle Cell Disease

PubMed Central

Gorbach, Alexander M.; Ackerman, Hans C.; Liu, Wei-Min; Meyer, Joseph M.; Littel, Patricia L.; Seamon, Catherine; Footman, Eleni; Chi, Amy; Zorca, Suzana; Krajewski, Megan L.; Cuttica, Michael J.; Machado, Roberto F.; Cannon, Richard O.; Kato, Gregory J.

2012-01-01

Vascular dysfunction is an important pathophysiologic manifestation of sickle cell disease (SCD), a condition that increases risk of pulmonary hypertension and stroke. We hypothesized that infrared (IR) imaging would detect changes in cutaneous blood flow reflective of vascular function. We performed IR imaging and conventional strain gauge plethysmography in twenty-five adults with SCD at baseline and during intra-arterial infusions of an endothelium-dependent vasodilator acetylcholine (ACh), an endothelium-independent vasodilator sodium nitroprusside (SNP), and a NOS inhibitor L-NMMA. Skin temperature measured by IR imaging increased in a dose-dependent manner to graded infusions of ACh (+1.1° C, p < 0.0001) and SNP (+0.9° C, p < 0.0001), and correlated with dose-dependent increases in forearm blood flow (ACh: +19.9 mL/min/100mL, p < 0.0001; rs = 0.57, p = 0.003; SNP: +8.6 mL/min/100mL, p < 0.0001; r = 0.70, p = 0.0002). Although IR measurement of skin temperature accurately reflected agonist-induced increases in blood flow, it was less sensitive to decreases in blood flow caused by NOS inhibition. Baseline forearm skin temperature measured by IR imaging correlated significantly with baseline forearm blood flow (31.8±0.2° C, 6.0±0.4 mL/min/100mL; r = 0.58, p = 0.003), and appeared to represent a novel biomarker of vascular function. It predicted a blunted blood flow response to SNP (r = −0.61, p = 0.002), and was independently associated with a marker of pulmonary artery pressure, as well as hemoglobin level, diastolic blood pressure, homocysteine, and cholesterol (R2 = 0.84, p < 0.0001 for the model). IR imaging of agonist-stimulated cutaneous blood flow represents a less cumbersome alternative to plethysmography methodology. Measurement of baseline skin temperature by IR imaging may be a useful new marker of vascular risk in adults with SCD. PMID:22784510

Preparation and characterization of ibuprofen-cetyl alcohol beads by melt solidification technique: effect of variables.

PubMed

Maheshwari, Manish; Ketkar, Anant R; Chauhan, Bhaskar; Patil, Vinay B; Paradkar, Anant R

2003-08-11

Ibuprofen (IBU) exhibits short half-life, poor compressibility, flowability and caking tendency. IBU melt has sufficiently low viscosity and exhibits interfacial tension sufficient to form droplet even at low temperature. A single step novel melt solidification technique (MST) was developed to produce IBU beads with lower amounts of excipient. Effect of variables was studied using a 3(2) factorial approach with speed of agitation and amount of cetyl alcohol (CA) as variables. The beads were evaluated using DSC, FT-IR and scanning electron microscope (SEM). Yield, micromeritic properties, crushing strength and release kinetics were also studied. Spherical beads with a method yield of above 90% were obtained. The data was analyzed by response surface methodology. The variables showed curvilinear relationship with yield in desired particle size range, crushing strength and, bulk and tap density. The drug release followed non-Fickian case II transport and the release rate decreased linearly with respect to amount of CA in the initial stages followed by curvilinearity at later stages of elution. The effect of changing porosity and tortuosity was well correlated.

Incorporating Planetary-Scale Waves Into the VTGCM: Understanding the Waves Impact on the Upper Atmosphere of Venus.

NASA Technical Reports Server (NTRS)

Brecht, A. S.; Bougher, S. W.; Shields, D.; Liu, H.

2017-01-01

Venus has proven to have a very dynamic upper atmosphere. The upper atmosphere of Venus has been observed for many decades by multiple means of observation (e.g. ground-based, orbiters, probes, fly-by missions going to other planets). As of late, the European Space Agency Venus Express (VEX) orbiter has been a main observer of the Venusian atmosphere. Specifically, observations of Venus' O2 IR nightglow emission have been presented to show its variability. Nightglow emission is directly connected to Venus' circulation and is utilized as a tracer for the atmospheric global wind system. More recent observations are adding and augmenting temperature and density (e.g. CO, CO2, SO2) datasets. These additional datasets provide a means to begin analyzing the variability and study the potential drivers of the variability. A commonly discussed driver of variability is wave deposition. Evidence of waves has been observed, but these waves have not been completely analyzed to understand how and where they are important. A way to interpret the observations and test potential drivers is by utilizing numerical models.

High-resolution TNG spectra of T Tauri stars. Near-IR GIANO observations of the young variables XZ Tauri and DR Tauri

NASA Astrophysics Data System (ADS)

Antoniucci, S.; Nisini, B.; Biazzo, K.; Giannini, T.; Lorenzetti, D.; Sanna, N.; Harutyunyan, A.; Origlia, L.; Oliva, E.

2017-10-01

Aims: We aim to characterise the star-disk interaction region in T Tauri stars that show photometric and spectroscopic variability. Methods: We used the GIANO instrument at the Telescopio Nazionale Galileo to obtain near-infrared high-resolution spectra (R 50 000) of XZ Tau and DR Tau, which are two actively accreting T Tauri stars classified as EXors. Equivalent widths and profiles of the observed features are used to derive information on the properties of the inner disk, the accretion columns, and the winds. Results: Both sources display composite H I line profiles, where contributions from both accreting gas and high-velocity winds can be recognised. These lines are progressively more symmetric and narrower with increasing upper energy which may be interpreted in terms of two components with different decrements or imputed to self-absorption effects. XZ Tau is observed in a relatively high state of activity with respect to literature observations. The variation of the He I 1.08 μm line blue-shifted absorption, in particular, suggests that the inner wind has undergone a dramatic change in its velocity structure, connected with a recent accretion event. DR Tau has a more stable wind as its He I 1.08 μm absorption does not show variations with time in spite of strong variability of the emission component. The IR veiling in the two sources can be interpreted as due to blackbody emission at temperatures of 1600 K and 2300 K for XZ Tau and DR Tau, respectively, with emitting areas 30 times larger than the central star. While for XZ Tau these conditions are consistent with emission from the inner rim of the dusty disk, the fairly high temperature inferred for DR Tau might suggest that its veiling originates from a thick gaseous disk located within the dust sublimation radius. Strong and broad metallic lines, mainly from C I and Fe I, are detected in XZ Tau, similar to those observed in other EXor sources during burst phases. At variance, DR Tau shows weaker and narrower metallic lines, despite its larger accretion luminosity. This suggests that accretion is not the only driver of metallic line excitation. Conclusions: The presented observations demonstrate the potential of wide-band, high-resolution near-IR spectroscopy to simultaneously probe the different phenomena that occur in the interaction region between the stellar magnetosphere and the accretion disk, thus providing hints on how these two structures are linked to each other.

Electrically-Active Convection and Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.

2010-01-01

It has been hypothesized that deep, intense convective-scale "hot" towers may aid the process of tropical cyclogenesis and intensification through dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this study, we make use of NCEP Reanalysis data and Tropical Rainfall Measurement Mission (TRMM) lightning imaging sensor (LIS), precipitation radar (PR), and microwave imager (TMI) data to investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") present in African easterly waves (AEWs) may play in tropical cyclogenesis over the Atlantic, Caribbean, and East Pacific regions. NCEP Reanalysis 700 hPa meridional winds for the months of June to November for the years 2001-2009 were analyzed for the domain of 5degN-20degN and 130degW-20degE in order to partition individual AEWs into northerly, southerly, trough, and ridge phases. Subsequently, information from National Hurricane Center (NHC) storm reports was used to divide the waves into developing and non-developing waves and to further divide the developing waves into those waves that spawned storms that only developed to tropical storm strength and those that spawned storms that reached hurricane strength. The developing waves were also divided by the region in which they developed. To help determine the gross nature of the smaller convective scale, composites were created of all developing and non-developing waves as a function of AEW wave phase over the full analysis domain and over various smaller longitude bands by compositing TRMM PR, TMI, LIS, and IR brightness temperature data extracted from the NASA global-merged IR brightness temperature dataset. Finally, similar composites were created using various NCEP variables to assess the nature of the larger scale environment and circulation. Results suggest a clear distinction between developing and non-developing waves as developing waves near their region of development in terms of the intensity of convection (indicated by lightning flash rate), coverage of cold cloudiness (indicated by the percentage of a 2.5deg by 2.5deg box covered by IR brightness temperatures less than 210 K), and large-scale variables, such as midlevel moisture and upper-level upward motion. For example, waves that developed in the East Pacific longitude band (i.e., 130degW-95degW) were observed in that band to have a flash rate of 56.4 flashes/day, a coverage by brightness temperatures less than 210 K equal to 2.2%, a 700-hPa specific humidity anomaly of 0.4 g/kg, and a 300-hPa omega value of -0.04 Pascals/s in the trough phase compared to the non-developing wave trough values of 22.1 flashes/day, a coverage by brightness temperatures less than 210 K equal to 0.9%, a 700-hPa specific humidity anomaly of -0.3 g/kg, and a 300-hPa omega value of -0.01 Pascals/s.

MTF measurement of IR optics in different temperature ranges

NASA Astrophysics Data System (ADS)

Bai, Alexander; Duncker, Hannes; Dumitrescu, Eugen

2017-10-01

Infrared (IR) optical systems are at the core of many military, civilian and manufacturing applications and perform mission critical functions. To reliably fulfill the demanding requirements imposed on today's high performance IR optics, highly accurate, reproducible and fast lens testing is of crucial importance. Testing the optical performance within different temperature ranges becomes key in many military applications. Due to highly complex IR-Applications in the fields of aerospace, military and automotive industries, MTF Measurement under realistic environmental conditions become more and more relevant. A Modulation Transfer Function (MTF) test bench with an integrated thermal chamber allows measuring several sample sizes in a temperature range from -40 °C to +120°C. To reach reliable measurement results under these difficult conditions, a specially developed temperature stable design including an insulating vacuum are used. The main function of this instrument is the measurement of the MTF both on- and off-axis at up to +/-70° field angle, as well as measurement of effective focal length, flange focal length and distortion. The vertical configuration of the system guarantees a small overall footprint. By integrating a high-resolution IR camera with focal plane array (FPA) in the detection unit, time consuming measurement procedures such as scanning slit with liquid nitrogen cooled detectors can be avoided. The specified absolute accuracy of +/- 3% MTF is validated using internationally traceable reference optics. Together with a complete and intuitive software solution, this makes the instrument a turn-key device for today's state-of- the-art optical testing.

Highly sensitive room temperature ammonia gas sensor based on Ir-doped Pt porous ceramic electrodes

NASA Astrophysics Data System (ADS)

Liu, Wenlong; Liu, Yen-Yu; Do, Jing-Shan; Li, Jing

2016-12-01

Room temperature NH3 gas sensors based on Pt and Pt-Ir (Ir doping Pt) porous ceramic electrodes have been fabricated by both electroplating and sputtering methods. The properties of the gaseous ammonia sensors have been examined by polarization and chronoamperometry techniques. The influence of humidity on the features of the resulting sensors in the system has also been discussed, and the working potential was optimized. Water vapors seem to hugely improve the electrochemical activity of the electrode. With increasing the relative humidity, the response of the Pt-Ir(E)/Pt(S)/PCP sensor to NH3 gas could be enhanced remarkably, and the sensitivity increases from 1.14 to 12.06 μA ppm-1 cm-2 .Then we have also discussed the sensing mechanism of the Pt-Ir sensor and the result has been confirmed by X-ray photoelectron spectroscopy of the electrode surface before and after reaction in the end.

Thermal-to-visible transducer (TVT) for thermal-IR imaging

NASA Astrophysics Data System (ADS)

Flusberg, Allen; Swartz, Stephen; Huff, Michael; Gross, Steven

2008-04-01

We have been developing a novel thermal-to-visible transducer (TVT), an uncooled thermal-IR imager that is based on a Fabry-Perot Interferometer (FPI). The FPI-based IR imager can convert a thermal-IR image to a video electronic image. IR radiation that is emitted by an object in the scene is imaged onto an IR-absorbing material that is located within an FPI. Temperature variations generated by the spatial variations in the IR image intensity cause variations in optical thickness, modulating the reflectivity seen by a probe laser beam. The reflected probe is imaged onto a visible array, producing a visible image of the IR scene. This technology can provide low-cost IR cameras with excellent sensitivity, low power consumption, and the potential for self-registered fusion of thermal-IR and visible images. We will describe characteristics of requisite pixelated arrays that we have fabricated.

The Ionotropic Receptors IR21a and IR25a mediate cool sensing in Drosophila.

PubMed

Ni, Lina; Klein, Mason; Svec, Kathryn V; Budelli, Gonzalo; Chang, Elaine C; Ferrer, Anggie J; Benton, Richard; Samuel, Aravinthan Dt; Garrity, Paul A

2016-04-29

Animals rely on highly sensitive thermoreceptors to seek out optimal temperatures, but the molecular mechanisms of thermosensing are not well understood. The Dorsal Organ Cool Cells (DOCCs) of the Drosophila larva are a set of exceptionally thermosensitive neurons critical for larval cool avoidance. Here, we show that DOCC cool-sensing is mediated by Ionotropic Receptors (IRs), a family of sensory receptors widely studied in invertebrate chemical sensing. We find that two IRs, IR21a and IR25a, are required to mediate DOCC responses to cooling and are required for cool avoidance behavior. Furthermore, we find that ectopic expression of IR21a can confer cool-responsiveness in an Ir25a-dependent manner, suggesting an instructive role for IR21a in thermosensing. Together, these data show that IR family receptors can function together to mediate thermosensation of exquisite sensitivity.

Metal-Insulator Transition in Epitaxial Pyrochlore Iridates Bi2Ir2O7 thin Films

NASA Astrophysics Data System (ADS)

Chu, Jiun-Haw; Liu, Jian; Yi, Di; Rayan-Serrao, C.; Suresha, S.; Marti, Xavi; Riggs, Scott; Shapiro, Max; Ian, Fisher; Ramesh, R.

2013-03-01

Recently there is a surge of interest in searching for topological order in correlated electronic systems such as transition metal oxides. The strong spin-orbit interaction of 5d electrons and the geometric frustration in the crystal lattice make the pyrochlore iridate(A2Ir2O7) an ideal candidate to achieve this goal. Pioneering experiments on bulk polycrystalline and single crystal samples revealed a temperature dependent metal-insulator transition coupled to a long range magnetic order, and the transition temperature can be tuned by either A-site ionic radius or an external pressure. In this talk we present our efforts to understand and control the metal-insulator transition and the underlying electronic structure of pyrochlore iridates via epitaxial Bi2Ir2O7 thin films. Bulk Bi2Ir2O7 is located at the metallic side of the phase diagram. However as the film's thickness decreases the transport evolves from a metallic to a strongly localized character. Resonant X-ray spectroscopy suggests that the density of states near Fermi level is dominated by the Ir Je ff =1/2 states. Intriguingly, the magnetoresistance shows a linear field dependence over a wide range of fields at low temperatures, which is possibly consistent with the existence of Dirac nodes.

Reverberation Mapping the Dusty Torus in Active Galactic Nuclei: the Influence of Torus Geometry and Structure on the Measured Reverberation Radius

NASA Astrophysics Data System (ADS)

Almeyda, Triana

2018-01-01

The obscuring circumnuclear dusty torus is a cornerstone of AGN unification, yet its shape, composition, and structure have not been well constrained. Infrared (IR) interferometry can partially resolve the dust structures in nearby AGN. However, the size and structure of the torus can also be investigated at all redshifts by reverberation mapping, that is, analyzing the temporal variability of the torus dust emission in response to changes in the AGN luminosity. In simple models, the lag between the AGN optical continuum variations and the torus IR response is directly related to the effective size of the emitting region. However, the IR response is sensitive to many poorly constrained variables including the geometry and illumination of the torus, which complicates the interpretation of measured reverberation lags. I will present results from the first comprehensive analysis of the multi-wavelength IR torus response, showing how various structural and geometrical torus parameters influence the measured lag. A library of torus response functions has been computed using a new code, TORMAC, which simulates the temporal response of the IR emission of a 3D ensemble of dust clouds given an input optical light curve. TORMAC accounts for anisotropic emission from the dust clouds, inter-cloud and AGN-cloud shadowing, and anisotropic illumination of the torus by the AGN continuum source. We can use the model grid to quantify the relationship between the lag and the effective size of the torus for various torus parameters at any selected wavelength. Although the shapes of the response functions vary widely over our grid parameter range, the reverberation lag provides an estimate of the effective torus radius that is always within a factor of 2.5. TORMAC can also be used to model observed IR light curves; we present preliminary simulations for the “changing-look” Seyfert galaxy, NGC 6418, which exhibited large IR variability during a recent Spitzer monitoring campaign. This work will aid in the interpretation of reverberation mapping measurements, especially for the new VEILS wide field near-IR extragalactic time domain survey, whose aim is to use AGN IR reverberation mapping lags as cosmological standard candles.

Shutterless non-uniformity correction for the long-term stability of an uncooled long-wave infrared camera

NASA Astrophysics Data System (ADS)

Liu, Chengwei; Sui, Xiubao; Gu, Guohua; Chen, Qian

2018-02-01

For the uncooled long-wave infrared (LWIR) camera, the infrared (IR) irradiation the focal plane array (FPA) receives is a crucial factor that affects the image quality. Ambient temperature fluctuation as well as system power consumption can result in changes of FPA temperature and radiation characteristics inside the IR camera; these will further degrade the imaging performance. In this paper, we present a novel shutterless non-uniformity correction method to compensate for non-uniformity derived from the variation of ambient temperature. Our method combines a calibration-based method and the properties of a scene-based method to obtain correction parameters at different ambient temperature conditions, so that the IR camera performance can be less influenced by ambient temperature fluctuation or system power consumption. The calibration process is carried out in a temperature chamber with slowly changing ambient temperature and a black body as uniform radiation source. Enough uniform images are captured and the gain coefficients are calculated during this period. Then in practical application, the offset parameters are calculated via the least squares method based on the gain coefficients, the captured uniform images and the actual scene. Thus we can get a corrected output through the gain coefficients and offset parameters. The performance of our proposed method is evaluated on realistic IR images and compared with two existing methods. The images we used in experiments are obtained by a 384× 288 pixels uncooled LWIR camera. Results show that our proposed method can adaptively update correction parameters as the actual target scene changes and is more stable to temperature fluctuation than the other two methods.

Effective mie-scattering and CO2 absorption in the dust-laden Martian atmosphere and its impact on radiative-convective temperature changes in the lower scale heights

NASA Technical Reports Server (NTRS)

Pallmann, A. J.

1976-01-01

A time dependent computer model of radiative-convective-conductive heat transfer in the Martian ground-atmosphere system was refined by incorporating an intermediate line strength CO2 band absorption which together with the strong-and weak-line approximation closely simulated the radiative transmission through a vertically inhomogeneous stratification. About 33,000 CO2 lines were processed to cover the spectral range of solar and planetary radiation. Absorption by silicate dust particulates, was taken into consideration to study its impact on the ground-atmosphere temperature field as a function of time. This model was subsequently attuned to IRIS, IR-radiometric and S-band occultation data. Satisfactory simulations of the measured IRIS spectra were accomplished for the dust-free condition. In the case of variable dust loads, the simulations were sufficiently fair so that some inferences into the effect of dust on temperature were justified.

The Viewing Geometry of Brown Dwarfs Influences Their Observed Colors and Variability Amplitudes

NASA Astrophysics Data System (ADS)

Vos, Johanna M.; Allers, Katelyn N.; Biller, Beth A.

2017-06-01

In this paper we study the full sample of known Spitzer [3.6 μm] and J-band variable brown dwarfs. We calculate the rotational velocities, v\\sin I, of 16 variable brown dwarfs using archival Keck NIRSPEC data and compute the inclination angles of 19 variable brown dwarfs. The results obtained show that all objects in the sample with mid-IR variability detections are inclined at an angle > 20^\\circ , while all objects in the sample displaying J-band variability have an inclination angle > 35^\\circ . J-band variability appears to be more affected by inclination than Spitzer [3.6 μm] variability, and is strongly attenuated at lower inclinations. Since J-band observations probe deeper into the atmosphere than mid-IR observations, this effect may be due to the increased atmospheric path length of J-band flux at lower inclinations. We find a statistically significant correlation between the color anomaly and inclination of our sample, where field objects viewed equator-on appear redder than objects viewed at lower inclinations. Considering the full sample of known variable L, T, and Y spectral type objects in the literature, we find that the variability properties of the two bands display notably different trends that are due to both intrinsic differences between bands and the sensitivity of ground-based versus space-based searches. However, in both bands we find that variability amplitude may reach a maximum at ˜7-9 hr periods. Finally, we find a strong correlation between color anomaly and variability amplitude for both the J-band and mid-IR variability detections, where redder objects display higher variability amplitudes.

Passive infrared ice detection for helicopter applications

NASA Technical Reports Server (NTRS)

Dershowitz, Adam L.; Hansman, R. John, Jr.

1990-01-01

A technique is proposed to remotely detect rotor icing on helicopters by using passive IR thermometry to detect the warming caused by latent heat release as supercooled water freezes. During icing, the ice accretion region will be warmer than the uniced trailing edge, resulting in a characteristic chordwise temperature profile. Preliminary tests were conducted on a static model in the NASA Icing Research Tunnel for a variety of wet (glaze) and dry (rime) ice conditions. The chordwise temperature profiles were confirmed by observation with an IR thermal video system and thermocouple observations. The IR observations were consistent with predictions of the LEWICE ice accretion code, which was used to extrapolate the observations to rotor icing conditions. Based on the static observations, the passive IR ice detection technique appears promising; however, further testing or rotating blades is required.

Edison and radiatively-cooled IR space observatories

NASA Technical Reports Server (NTRS)

Thronson, H. A.; Hawarden, T. G.; Bally, J.; Burnell, S. J. Bell; Penny, A. J.; Rapp, D.

1993-01-01

Radiative cooling of IR space telescopes is an alternative to embedding within massive cryostats and should offer advantages for future missions, including longer life, larger aperture for a fixed spacecraft size, lower cost due to less complex engineering, and easier ground handling. Relatively simple analyses of conventional designs show that it is possible to achieve telescope temperatures in the range of 25 to 40 K at distances from the sun of about 1 AU. Lower temperatures may be possible with 'open' designs or distant orbits. At approximately 25 K, an observatory will be limited by the celestial thermal background in the near- and mid-IR and by the confusion limit in the far-IR. We outline here our concept for a moderate aperture (approximately 1.75 m; Ariane 4 or Atlas launch) international space observatory for the next decade.

Mesospheric effects of solar ultraviolet variations - Further analysis of SME IR ozone and Nimbus 7 SAMS temperature data

NASA Astrophysics Data System (ADS)

Hood, L. L.; Huang, Z.; Bougher, S. W.

1991-07-01

In order to improve the constraints on models of the mesospheric response to solar UV variations, an analysis is conducted of the Solar Mesosphere Explorer (SME) IR ozone data and Nimbus 7 stratosphere and mesosphere sounder (SAMS) temperature data. Maximum low-altitude ozone and temperature-response amplitudes occur at about the same altitude, where a strong coupling between photochemical and thermal components of the mesospheric response is suggested by the simultaneous positive temperature and negative ozone response maxima. Increased Lyman-alpha dissociation of water vapor and temperature feedback are theorized to account for the negative ozone response. HO(x) chemical heating can increase as ozone destruction increases, and can therefore account for the positive temperature response.

Mesospheric effects of solar ultraviolet variations - Further analysis of SME IR ozone and Nimbus 7 SAMS temperature data

NASA Technical Reports Server (NTRS)

Hood, L. L.; Huang, Z.; Bougher, S. W.

1991-01-01

In order to improve the constraints on models of the mesospheric response to solar UV variations, an analysis is conducted of the Solar Mesosphere Explorer (SME) IR ozone data and Nimbus 7 stratosphere and mesosphere sounder (SAMS) temperature data. Maximum low-altitude ozone and temperature-response amplitudes occur at about the same altitude, where a strong coupling between photochemical and thermal components of the mesospheric response is suggested by the simultaneous positive temperature and negative ozone response maxima. Increased Lyman-alpha dissociation of water vapor and temperature feedback are theorized to account for the negative ozone response. HO(x) chemical heating can increase as ozone destruction increases, and can therefore account for the positive temperature response.

PGE in fresh basalt, hydrothermal alteration products, and volcanic incrustations of Kilauea volcano, Hawaii

NASA Astrophysics Data System (ADS)

Crocket, James H.

2000-05-01

The concentrations of Os, Ir, Pd, and Au in fresh unaltered Kilauean tholeiite were determined by radiochemical neutron activation analysis. For a suite of 18 samples, averages were: Os = 0.38 ± 0.23, Ir = 0.38 ± 0.14, Pd = 2.40 ± 1.04, and Au = 1.78 ± 0.57 (in ppb with a 1σ SD). Correlations of these metals with Co, Cr, Cu, Ni, and MgO in fresh basalts, and petrographic observations, indicate that Os and Ir are carried mainly in chromite, much of which occurs as inclusions in olivine phenocrysts. Palladium correlations suggest its occurrence partly in olivine and partly in the matrix whereas Au seems to be predominantly a matrix constituent. Altered basalts were analyzed for Ir, Pd, and Au in a suite of 19 samples from five different locations. Minor changes only in either concentrations or element ratios were found for Ir and Pd when fresh and altered rock data were compared. However, Au was consistently enriched in altered relative to fresh rocks. These results imply that Pd and Ir, in contrast to Au, will likely retain their eruptive signatures upon burial in a subaerial eruptive setting. High-temperature sulfate-dominated condensates generate incrustations enriched in Ir, Os, Au, and Pd by approximately 50, 20, 10, and 3×, respectively, relative to fresh rocks. In contrast, low-temperature native sulfur deposits are the most depleted material found in the study with Ir, Pd, and Au lower by factors of 10, 4, and 5 compared with fresh rock averages. The strong enrichments of Os and Ir in the high-temperature suite are attributed mainly to enhanced volatility in highly oxygenated magmatic hydrothermal fluids contaminated by meteoric water near the structural top of volcanic conduits. The relatively smaller Pd enrichment, which is dependent on the chloride content of fluids, implies that PGE partitioning into volcanic fume may fractionate these metals (e.g., Pd versus Ir) relative to host basalt in the eruptive process.

RISING FROM THE ASHES: MID-INFRARED RE-BRIGHTENING OF THE IMPOSTOR SN 2010da IN NGC 300

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

Lau, Ryan M.; Ressler, Michael E.; Kasliwal, Mansi M.

2016-10-20

We present multi-epoch mid-infrared (IR) photometry and the optical discovery observations of the “impostor” supernova (SN) 2010da in NGC 300 using new and archival Spitzer Space Telescope images and ground-based observatories. The mid-infrared counterpart of SN 2010da was detected as Spitzer Infrared Intensive Transient Survey (SPIRITS) 14bme in the SPIRITS, an ongoing systematic search for IR transients. Before erupting on 2010 May 24, the SN 2010da progenitor exhibited a constant mid-IR flux at 3.6 and only a slight ∼10% decrease at 4.5 μ m between 2003 November and 2007 December. A sharp increase in the 3.6 μ m flux followedmore » by a rapid decrease measured ∼150 days before and ∼80 days after the initial outburst, respectively, reveal a mid-IR counterpart to the coincident optical and high luminosity X-ray outbursts. At late times, after the outburst (∼2000 days), the 3.6 and 4.5 μ m emission increased to over a factor of two times the progenitor flux and is currently observed (as of 2016 Feb) to be fading, but still above the progenitor flux. We attribute the re-brightening mid-IR emission to continued dust production and increasing luminosity of the surviving system associated with SN 2010da. We analyze the evolution of the dust temperature ( T {sub d} ∼ 700–1000 K), mass ( M {sub d} ∼ 0.5–3.8 × 10{sup −7} M {sub ⊙}), luminosity ( L {sub IR} ∼ 1.3–3.5 × 10{sup 4} L {sub ⊙}), and the equilibrium temperature radius ( R {sub eq} ∼ 6.4–12.2 au) in order to resolve the nature of SN 2010da. We address the leading interpretation of SN 2010da as an eruption from a luminous blue variable high-mass X-ray binary (HMXB) system. We propose that SN 2010da is instead a supergiant (sg)B[e]-HMXB based on similar luminosities and dust masses exhibited by two other known sgB[e]-HMXB systems. Additionally, the SN 2010da progenitor occupies a similar region on a mid-IR color–magnitude diagram (CMD) with known sgB[e] stars in the Large Magellanic Cloud. The lower limit estimated for the orbital eccentricity of the sgB[e]-HMXB ( e > 0.82) from X-ray luminosity measurements is high compared to known sgHMXBs and supports the claim that SN 2010da may be associated with a newly formed HMXB system.« less

Combined IR imaging-neural network method for the estimation of internal temperature in cooked chicken meat

NASA Astrophysics Data System (ADS)

Ibarra, Juan G.; Tao, Yang; Xin, Hongwei

2000-11-01

A noninvasive method for the estimation of internal temperature in chicken meat immediately following cooking is proposed. The external temperature from IR images was correlated with measured internal temperature through a multilayer neural network. To provide inputs for the network, time series experiments were conducted to obtain simultaneous observations of internal and external temperatures immediately after cooking during the cooling process. An IR camera working at the spectral band of 3.4 to 5.0 micrometers registered external temperature distributions without the interference of close-to-oven environment, while conventional thermocouples registered internal temperatures. For an internal temperature at a given time, simultaneous and lagged external temperature observations were used as the input of the neural network. Based on practical and statistical considerations, a criterion is established to reduce the nodes in the neural network input. The combined method was able to estimate internal temperature for times between 0 and 540 s within a standard error of +/- 1.01 degree(s)C, and within an error of +/- 1.07 degree(s)C for short times after cooking (3 min), with two thermograms at times t and t+30s. The method has great potential for monitoring of doneness of chicken meat in conveyor belt type cooking and can be used as a platform for similar studies in other food products.

IR imaging of blood circulation of patients with vascular disease

NASA Astrophysics Data System (ADS)

Wang, Hsin; Wade, Dwight R., Jr.; Kam, Jack

2004-04-01

We conducted a preliminary IR imaging study of blood circulation in patients with peripheral vascular diseases. Abnormal blood flow is common in older adults, especially those with elevated blood lipids, diabetes, hypertension, and a history of smoking. All of these conditions have a high prevalence in our population, often with more than one condition in the same individual. The differences in blood flow is revealed by temperature differences in areas of the extremities as well as other regions of the body. However, what is needed is an imaging technique that is relatively inexpensive and can reveal the blood flow in real time. The IR imaging can show detailed venous system and small tempearture changes associated with blood flow. Six patients with vascular diseases were tested in a clinic set up. Their legs and feet were imaged. We observed large temperature differences (cooling of more than 10° C) at the foot, especially toes. More valuable information were obtained from the temperature distribution maps. IR thermography is potentially a very valuable tool for medical application, especially for vascular diseases.

An assessment of surface emissivity variation effects on plasma uniformity analysis using IR cameras

NASA Astrophysics Data System (ADS)

Greenhalgh, Abigail; Showers, Melissa; Biewer, Theodore

2017-10-01

The Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) is a linear plasma device operating at Oak Ridge National Laboratory (ORNL). Its purpose is to test plasma source and heating concepts for the planned Material Plasma Exposure eXperiment (MPEX), which has the mission to test the plasma-material interactions under fusion reactor conditions. In this device material targets will be exposed to high heat fluxes (>10 MW/m2). To characterize the heat fluxes to the target a IR thermography system is used taking up to 432 frames per second videos. The data is analyzed to determine the surface temperature on the target in specific regions of interest. The IR analysis has indicated a low level of plasma uniformity; the plasma often deposits more heat to the edge of the plate than the center. An essential parameter for IR temperature calculation is the surface emissivity of the plate (stainless steel). A study has been performed to characterize the variation in the surface emissivity of the plate as its temperature changes and its surface finish is modified by plasma exposure.

System and method for online inspection of turbines using an optical tube with broadspectrum mirrors

DOEpatents

Baleine, Erwan

2015-12-22

An optical inspection system for nondestructive internal visual inspection and non-contact infra-red (IR) temperature monitoring of an online, operating power generation turbine. The optical inspection system includes an optical tube having a viewing port, at least one reflective mirror or a mirror array having a reflectivity spectral range from 550 nm to 20 .mu.m, and capable of continuous operation at temperatures greater than 932 degrees Fahrenheit (500 degrees Celsius), and a transparent window with high transmission within the same spectral range mounted distal the viewing port. The same optical mirror array may be used to measure selectively surface temperature of metal turbine blades in the near IR range (approximately 1 .mu.m wavelength) and of thermal barrier coated turbine blades in the long IR range (approximately 10 .mu.m wavelength).

TPD IR studies of CO desorption from zeolites CuY and CuX

NASA Astrophysics Data System (ADS)

Datka, Jerzy; Kozyra, Paweł

2005-06-01

The desorption of CO from zeolites CuY and CuX was followed by TPD-IR method. This is a combination of temperature programmed desorption and IR spectroscopy. In this method, the status of activated zeolite (before adsorption), the process of adsorption, and the status of adsorbed molecules can be followed by IR spectroscopy, and the process of desorption (with linear temperature increase) can be followed both by IR spectroscopy and by mass spectrometry. IR spectra have shown two kinds of Cu + sites in both CuY and CuX. Low frequency (l.f.) band (2140 cm -1 in CuY and 2130 cm -1 in CuX) of adsorbed CO represents Cu + sites for which π back donation is stronger and σ donation is weaker whereas high frequency h.f. band (2160 cm -1 in CuY and 2155 cm -1 in CuX) represent Cu + sites for which π back donation is weaker and σ donation is stronger. The TPD-IR experiments evidenced that the Cu + sites represented by l.f. band bond CO more weakly than those represented by h.f. one, indicating that σ donation has more important impact to the strength of Cu +-CO bonding. On the contrary, π back donation has bigger contribution to the activation of adsorbed molecules.

Structural characterization and observation of variable range hopping conduction mechanism at high temperature in CdSe quantum dot solids

NASA Astrophysics Data System (ADS)

Sinha, Subhojyoti; Kumar Chatterjee, Sanat; Ghosh, Jiten; Kumar Meikap, Ajit

2013-03-01

We have used Rietveld refinement technique to extract the microstructural parameters of thioglycolic acid capped CdSe quantum dots. The quantum dot formation and its efficient capping are further confirmed by HR-TEM, UV-visible and FT-IR spectroscopy. Comparative study of the variation of dc conductivity with temperature (298 K ≤ T ≤ 460 K) is given considering Arrhenius formalism, small polaron hopping and Schnakenberg model. We observe that only Schnakenberg model provides good fit to the non-linear region of the variation of dc conductivity with temperature. Experimental variation of ac conductivity and dielectric parameters with temperature (298 K ≤ T ≤ 460 K) and frequency (80 Hz ≤ f ≤ 2 MHz) are discussed in the light of hopping theory and quantum confinement effect. We have elucidated the observed non-linearity in the I-V curves (measured within ±50 V), at dark and at ambient light, in view of tunneling mechanism. Tunnel exponents and non-linearity weight factors have also been evaluated in this regard.

Low temperature fabrication of VO x thin films for uncooled IR detectors by direct current reactive magnetron sputtering method

NASA Astrophysics Data System (ADS)

Dai, Jun; Wang, Xingzhi; He, Shaowei; Huang, Ying; Yi, Xinjian

2008-03-01

Vanadium oxide films have been fabricated on Si3N4-film-coated silicon substrates by direct current reactive magnetron sputtering method. Conditions of deposition are optimized making use of parameters such as sputtering time, dc power, oxygen partial pressure and substrate temperature. X-ray diffraction indicates that the film is a mixture of VO2, V2O3, and V3O5. Four-probe measurement shows that the VOx thin film owns high temperature coefficient of resistance (TCR ∼-2.05%/°C) and suitable square resistance 18.40 kΩ/□ (measured at 25 °C), indicating it is a well candidate material for uncooled IR detectors. In addition, IR absorption in the wavelength of 2-16 μm has been characterized. It is worth noting that the films are sputtered at a relatively low temperature of 210 °C in a controlled Ar/O2 atmosphere. Compared to traditional craft, this method needs no post-anneal at high temperature (400-500 °C).

Images of the 10-micron source in the Cygnus 'Egg'

NASA Technical Reports Server (NTRS)

Jaye, D.; Fienberg, R. Tresch; Fazio, G. G.; Gezari, D. Y.; Lamb, G. M.; Shu, P. K.; Hoffmann, W. F.; Mccreight, C. R.

1989-01-01

Mid-IR images of AFGL 2688, the Egg nebula, obtained with a 16 x 16 pixel array camera (field of view 12.5 x 12.5 arcsec) resolve the central source. It appears as a centrally peaked ellipsoid with major axis of symmetry parallel to the axis of the visible nebulosity. This is contrary to the expected extension perpendicular to this axis implied by proposed dust-toroid models of the IR source. Maps of the spatial distribution of 8-13 micron color temperature and warm dust opacity derived from the multiwavelength images further characterize the IR emission. The remarkable flatness of the color temperature conflicts with the radial temperature gradient expected across a thick shell of material with a single heat source at its center. The new data suggest instead that the source consists of a central star surrounded by a dust shell that is too thin to provide a detectable temperature gradient and too small to permit the resolution of limb brightening.

Airflow analyses using thermal imaging in Arizona's Meteor Crater as part of METCRAX II

NASA Astrophysics Data System (ADS)

Grudzielanek, A. Martina; Vogt, Roland; Cermak, Jan; Maric, Mateja; Feigenwinter, Iris; Whiteman, C. David; Lehner, Manuela; Hoch, Sebastian W.; Krauß, Matthias G.; Bernhofer, Christian; Pitacco, Andrea

2016-04-01

In October 2013 the second Meteor Crater Experiment (METCRAX II) took place at the Barringer Meteorite Crater (aka Meteor Crater) in north central Arizona, USA. Downslope-windstorm-type flows (DWF), the main research objective of METCRAX II, were measured by a comprehensive set of meteorological sensors deployed in and around the crater. During two weeks of METCRAX II five infrared (IR) time lapse cameras (VarioCAM® hr research & VarioCAM® High Definition, InfraTec) were installed at various locations on the crater rim to record high-resolution images of the surface temperatures within the crater from different viewpoints. Changes of surface temperature are indicative of air temperature changes induced by flow dynamics inside the crater, including the DWF. By correlating thermal IR surface temperature data with meteorological sensor data during intensive observational periods the applicability of the IR method of representing flow dynamics can be assessed. We present evaluation results and draw conclusions relative to the application of this method for observing air flow dynamics in the crater. In addition we show the potential of the IR method for METCRAX II in 1) visualizing airflow processes to improve understanding of these flows, and 2) analyzing cold-air flows and cold-air pooling.

Combustor deployments of femtosecond laser written fiber Bragg grating arrays for temperature measurements surpassing 1000°C

NASA Astrophysics Data System (ADS)

Walker, Robert B.; Ding, Huimin; Coulas, David; Mihailov, Stephen J.; Duchesne, Marc A.; Hughes, Robin W.; McCalden, David J.; Burchat, Ryan; Yandon, Robert; Yun, Sangsig; Ramachandran, Nanthan; Charbonneau, Michel

2017-05-01

Femtosecond Infrared (fs-IR) laser written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent to advanced power plant technologies and gas turbine engines, under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper reviews our fabrication and deployment of hundreds of fs-IR written FBGs, for monitoring temperature gradients of an oxy-fuel fluidized bed combustor and an aerospace gas turbine combustor simulator.

On formation mechanism of Pd-Ir bimetallic nanoparticles through thermal decomposition of [Pd(NH3)4][IrCl6

NASA Astrophysics Data System (ADS)

Asanova, Tatyana I.; Asanov, Igor P.; Kim, Min-Gyu; Gerasimov, Evgeny Yu.; Zadesenets, Andrey V.; Plyusnin, Pavel E.; Korenev, Sergey V.

2013-10-01

The formation mechanism of Pd-Ir nanoparticles during thermal decomposition of double complex salt [Pd(NH3)4][IrCl6] has been studied by in situ X-ray absorption (XAFS) and photoelectron (XPS) spectroscopies. The changes in the structure of the Pd and Ir closest to the surroundings and chemical states of Pd, Ir, Cl, and N atoms were traced in the range from room temperature to 420 °C in inert atmosphere. It was established that the thermal decomposition process is carried out in 5 steps. The Pd-Ir nanoparticles are formed in pyramidal/rounded Pd-rich (10-200 nm) and dendrite Ir-rich (10-50 nm) solid solutions. A d charge depletion at Ir site and a gain at Pd, as well as the intra-atomic charge redistribution between the outer d and s and p electrons of both Ir and Pd in Pd-Ir nanoparticles, were found to occur.

Distinct combinations of variant ionotropic glutamate receptors mediate thermosensation and hygrosensation in Drosophila.

PubMed

Knecht, Zachary A; Silbering, Ana F; Ni, Lina; Klein, Mason; Budelli, Gonzalo; Bell, Rati; Abuin, Liliane; Ferrer, Anggie J; Samuel, Aravinthan Dt; Benton, Richard; Garrity, Paul A

2016-09-22

Ionotropic Receptors (IRs) are a large subfamily of variant ionotropic glutamate receptors present across Protostomia. While these receptors are most extensively studied for their roles in chemosensory detection, recent work has implicated two family members, IR21a and IR25a, in thermosensation in Drosophila . Here we characterize one of the most evolutionarily deeply conserved receptors, IR93a, and show that it is co-expressed and functions with IR21a and IR25a to mediate physiological and behavioral responses to cool temperatures. IR93a is also co-expressed with IR25a and a distinct receptor, IR40a, in a discrete population of sensory neurons in the sacculus, a multi-chambered pocket within the antenna. We demonstrate that this combination of receptors is required for neuronal responses to dry air and behavioral discrimination of humidity differences. Our results identify IR93a as a common component of molecularly and cellularly distinct IR pathways important for thermosensation and hygrosensation in insects.

Analysis of Thermal Imagery Collected at Grayling II, Grayling, Michigan

DTIC Science & Technology

1994-11-01

during Grayling II exercise ............................................. 36 12 Deciduous (black oak) treeline LWB and SWB IR signatures and air... treeline LWB and SWB IR signaures and air temperature (E3 station, 2 m above ground) during Grayling I exercise ................................. 39 ii...tree. e. Deciduous (black oak) treeline . f. Coniferous (pine) tree. g. Coniferous (pine) treeline . Figure 4 contains color photographs and IR images

Infrared observations of an outburst of small dust grains from the nucleus of Comet P/Halley 1986 III at perihelion

NASA Technical Reports Server (NTRS)

Gehrz, R. D.; Johnson, C. H.; Magnuson, S. D.; Ney, E. P.; Hayward, T. L.

1995-01-01

A close examination of the 0.7- to 23-micron infrared data base acquired by Gehrz and Ney (1992), suggests that the nucleus of Comet P/Halley 1986 III emitted a burst of small dust grains during a 3-day period commencing within hours of perihelion passage on 1986 February 9.46 UT. The outburst was characterized by significant increases in the coma's grain color temperature T(sub obs), temperature excess (superheat: S = T(sub obs)/T(sub BB)), infrared luminosity, albedo, and 10-micron silicate emission feature strength. These changes are all consistent with the sudden ejection from the nucleus of a cloud of grains with radii of approximately 0.5 micron. This outburst may have produced the dust that was responsible for some of the tail streamers photographed on 1986 February 22 UT. The peak of the dust outburst occurred about 3 days before a pronounced increase in the water production rate measured by the Pioneer Venus Orbiter Ultraviolet Spectrometer. We suggest that jets that release large quantities of small particles may be largely responsible for some of the variable infrared behavior that has been reported for P/Halley and other comets during the past two decades. Such jets may also account for some of the differences IR Type I and IR Type II comets.

Porous carbon materials synthesized using IRMOF-3 and furfuryl alcohol as precursor

NASA Astrophysics Data System (ADS)

Deka, Pemta Tia; Ediati, Ratna

2016-03-01

IRMOF-3 crystals have been synthesized using solvothermal method by adding zinc nitrate hexahydrate with 2-amino-1,4-benzenedicarboxylic acid in N'N-dimethylformamide (DMF) at 100°C for 24 (note as IR-24) and 72 h (note as IR-72). The obtained crystals were characterized using X-ray Diffraction (XRD), SEM (Scanning Electron Microscopy) and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), FTIR and Isothermal adsorption-desorption N2. The diffractogram solids synthesized show characteristic peak at 2θ 6.8, 9.6 and 13.7°. SEM micrograph show cubic shape of IRMOF-3 crystal. Based on FTIR characterization, IRMOF-3 appear at wavelength (1691,46; 1425,3; 1238,21; 1319,22 dan 3504,42)cm-1. The Isotherm of crystal IRMOF-3 at heating time 24 h and 72 h are type IV. The surface area of IR-24 and IR-72 are respectively 24,758 m2/g and 29,139 m2/g with its dominant mesopores. Carbonaceous materials has been successfully synthesized using IR-24, IR-72 and furfuryl alcohol (FA) as second carbon precursor with variation of carbonation temperature 550, 700 and 850°C. The XRD result from both carbonaceous materials show formation of amorphous carbon and caharacteristic peak of ZnO oxide. Micrograph SEM show that carbonaceous materials have cubic shape as IRMOF-3 and SEM-EDX result indicate Zn and nitrogen content of these materials has decrease until temperature 850°C. Porous carbon using IR-24 and FA (notes as C-24) has increased surface area with higher carbonation temperature. The highest surface area is 1495,023 m2/g. Total pore volume and pore size of C-24 from low to high temperature respectively as (0,338; 0,539 and 1,598) cc/g; (0,107; 0,152 and 0,610) cc/g. Porous carbon using IR-72 and FA (notes as C-72) has smaller surface area than C-24 but its also increased during higher carbonation heating. The highest surface area is 1029,668 m2/g.The total pore volume and pore size of these carbon materials from low to high temperature respectively as (0,390; 0,727 and 1,345) cc/g and (0,065; 0,157 and 0,381) cc/g. Carbonaceous materials with high porosity and nitrogen content will be expected increase mechanical properties and hydrogen storage from these materials.

A measurement system of high-temperature oxidation environment with ultrasonic Ir0.6Rth0.4 alloy thermometry.

PubMed

Wei, Yanlong; Wang, Gao; Gao, Yubin; Liu, Zhengguang; Xu, Lin; Tian, Miao; Yuan, Dongfang; Ren, Haiping; Zhou, Hanchang; Yang, Lu; Shi, Xueshun; Xiao, Zhaoqian

2018-04-03

Iridium-rhodium is generally applied as a thermocouple material, with max operating temperature about 2150 °C. In this study, a ultrasonic temperature measurement system was designed by using Iridium-rhodium (60%Ir-40%Rh) alloy as an acoustic waveguide sensor material, and the system was preliminarily tested in a high-temperature oxidation environment. The result of ultrasonic temperature measurement shows that this system can indeed work stably in high-temperature oxidation environments. The relationship between temperature and delay time of ultrasonic thermometry up to 2200 °C was illustrated. Iridium-rhodium materials were also investigated in order to fully elucidate the proposed waveguide sensor's performance in a high-temperature oxidation environment. This system lays a foundation for further application of high-temperature measurement. Copyright © 2018. Published by Elsevier B.V.

Noble metal abundances in komatiite suites from Alexo, Ontario and Gorgona Island, Colombia

NASA Astrophysics Data System (ADS)

Brügmann, G. E.; Arndt, N. T.; Hofmann, A. W.; Tobschall, H. J.

1987-08-01

The distribution of the chalcophile and siderophile metals Cu, Ni, Au, Pd, Ir, Os and Ru in an Archaean komatiite flow from Alexo, Ontario and in a Phanerozoic komatiitic suite of Gorgona Island, Colombia, provides new information about the geochemical behaviour of these elements. Copper, Au and Pd behave as incompatible elements during the crystallization of these ultramafic magmas. In contrast, Ni, Ir, Os and Ru concentrations systematically decrease with decreasing MgO contents, a pattern characteristic of compatible elements. These trends are most probably controlled by olivine crystallization, which implies that Ir, Os and Ru are compatible in olivine. Calculated partition coefficients for Ir, Os and Ru between olivine and the melt are about 1.8. Compared to primitive mantle, parental komatiitic liquids are enriched in (incompatible) Cu, Au and Pd and depleted in (compatible) Ir, Os and Ru. Within both Archaean and Phanerozoic komatiites, noble metal ratios such as Au/Pd, Ir/Os, Os/Ru and Ru/Ir and ratios of lithophile and siderophile elements such as Ti/Pd, Ti/Au are constant and similar to primitive mantle values. This implies that Au and Pd are moderately incompatible elements and that there has been no significant fractionation of siderophile and lithophile elements since the Archaean. Platinum-group element abundances of normal MORB are highly variable and always much lower than in komatiites, because MORB magma is saturated with sulfur and a variable but minor amount of sulfide segregated during mantle melting or during the ascent of magma to the surface. Sulfide deposits associated with komatiites display similar chalcophile element patterns to those of komatiites. Noble metal ratios such as Pd/Ir, Au/Ir, Pd/Os and Pd/Ru can be used to determine the composition of the host komatiite at the time of sulfide segregation.

Magnetic characteristics of polymorphic single crystal compounds DyIr2Si2

NASA Astrophysics Data System (ADS)

Uchima, Kiyoharu; Shigeoka, Toru; Uwatoko, Yoshiya

2018-05-01

We have confirmed that the tetragonal ternary compound DyIr2Si2 shows polymorphism; the ThCr2Si2-type structure as a low temperature phase (I-phase) and the CaBe2Ge2-type one as a high temperature phase (P-phase) exist. A comparative study on magnetic characteristics of the morphs was performed on the I- and P-phase single crystals in order to elucidate how magnetic properties are influenced by crystallographic symmetry. The magnetic behavior changes drastically depending on the structure. The DyIr2Si2(I) shows an antiferromagnetic ordering below TN = 30 K, additional magnetic transitions of T1 = 17 K and T2 = 10 K, and a strong uniaxial magnetic anisotropy with the easy [001] direction. The [001] magnetization shows four metamagnetic transitions at low temperatures. On the other hand, the DyIr2Si2(P) has comparatively low ordering temperature of TN1 = 9.4 K and an additional transition temperature of TN2 = 3.0 K, and exhibits an easy-plane magnetic anisotropy with the easy [110] direction. Two metamagnetic transitions appear in the basal plane magnetization processes. In both the morphs, the χ-T behavior suggests the existence of component-separated magnetic transitions. The ab-component of magnetic moments orders at the higher transition temperature TN1 for the P-phase compound, which is contrast to the I-phase behavior; the c-component orders firstly at TN. The crystalline electric field (CEF) analysis was made, and the difference in magnetic behaviors between both the morphs is explained by the CEF effects.

Photothermoelastic contrast in nanoscale infrared spectroscopy

NASA Astrophysics Data System (ADS)

Morozovska, Anna N.; Eliseev, Eugene A.; Borodinov, Nikolay; Ovchinnikova, Olga S.; Morozovsky, Nicholas V.; Kalinin, Sergei V.

2018-01-01

The contrast formation mechanism in nanoscale Infrared (IR) Spectroscopy is analyzed. The temperature distribution and elastic displacement across the illuminated T-shape boundary between two materials with different IR-radiation absorption coefficients and thermo-physical and elastic properties located on a rigid substrate are calculated self-consistently for different frequencies f ˜ (1 kHz-1 MHz) of IR-radiation modulation (fully coupled problem). Analytical expressions for the temperature and displacement profiles across the "thermo-elastic step" are derived in the decoupling approximation for f = 0 ("static limit"), and conditions for approximation validity at low frequencies of IR-modulation are established. The step height was found to be thickness-independent for thick layers and proportional to the square of the thickness for very thin films. The theoretical results will be of potential interest for applications in the scanning thermo-ionic and thermal infrared microscopies for relatively long sample thermalization times and possibly for photothermal induced resonance microscopy using optomechanical probes.

Basic properties and variability

NASA Technical Reports Server (NTRS)

Querci, Francois R.

1987-01-01

Giant and supergiant M, S, and C stars are discussed in this survey of research. Basic properties as determined by spectra, chemical composition, photometry, or variability type are discussed. Space motions and space distributions of cool giants are described. Distribution of these stars in our galaxy and those nearby is discussed. Mira variables in particular are surveyed with emphasis on the following topics: (1) phase lag phenomenon; (2) Mira light curves; (3) variations in color indices; (4) determination of multiple periods; (5) correlations between quantities such as period length, light-curve shape, infrared (IR) excess, and visible and IR color diagram; (6) semiregular (SR) variables and different time scales in SR light variations; (7) irregular variable Lb and Lc stars; (8) different time-scale light variations; (9) hydrogen-deficient carbon (HdC) stars, in particular RCB stars; and (10) irreversible changes and rapid evolution in red variable stars.

FT-MIR and NIR spectral data fusion: a synergetic strategy for the geographical traceability of Panax notoginseng.

PubMed

Li, Yun; Zhang, Jin-Yu; Wang, Yuan-Zhong

2018-01-01

Three data fusion strategies (low-llevel, mid-llevel, and high-llevel) combined with a multivariate classification algorithm (random forest, RF) were applied to authenticate the geographical origins of Panax notoginseng collected from five regions of Yunnan province in China. In low-level fusion, the original data from two spectra (Fourier transform mid-IR spectrum and near-IR spectrum) were directly concatenated into a new matrix, which then was applied for the classification. Mid-level fusion was the strategy that inputted variables extracted from the spectral data into an RF classification model. The extracted variables were processed by iterate variable selection of the RF model and principal component analysis. The use of high-level fusion combined the decision making of each spectroscopic technique and resulted in an ensemble decision. The results showed that the mid-level and high-level data fusion take advantage of the information synergy from two spectroscopic techniques and had better classification performance than that of independent decision making. High-level data fusion is the most effective strategy since the classification results are better than those of the other fusion strategies: accuracy rates ranged between 93% and 96% for the low-level data fusion, between 95% and 98% for the mid-level data fusion, and between 98% and 100% for the high-level data fusion. In conclusion, the high-level data fusion strategy for Fourier transform mid-IR and near-IR spectra can be used as a reliable tool for correct geographical identification of P. notoginseng. Graphical abstract The analytical steps of Fourier transform mid-IR and near-IR spectral data fusion for the geographical traceability of Panax notoginseng.

Randomized double-blind comparison of cognitive and EEG effects of lacosamide and carbamazepine.

PubMed

Meador, Kimford J; Loring, David W; Boyd, Alan; Echauz, Javier; LaRoche, Suzette; Velez-Ruiz, Naymee; Korb, Pearce; Byrnes, William; Dilley, Deanne; Borghs, Simon; De Backer, Marc; Story, Tyler; Dedeken, Peter; Webster, Elizabeth

2016-09-01

Differential effectiveness of antiepileptic drugs (AEDs) is more commonly determined by tolerability than efficacy. Cognitive effects of AEDs can adversely affect tolerability and quality of life. This study evaluated cognitive and EEG effects of lacosamide (LCM) compared with carbamazepine immediate-release (CBZ-IR). A randomized, double-blind, double-dummy, two-period crossover, fixed-dose study in healthy subjects compared neuropsychological and EEG effects of LCM (150mg, b.i.d.) and CBZ-IR (200mg, t.i.d.). Testing was conducted at screening, predrug baseline, the end of each treatment period (3-week titration; 3-week maintenance), and the end of each washout period (4weeks after treatment). A composite Z-score was derived for the primary outcome variable (computerized cognitive tests and traditional neuropsychological measures) and separately for the EEG measures. Other variables included individual computer, neuropsychological, and EEG scores and adverse events (AEs). Subjects included 60 healthy adults (57% female; mean age: 34.4years [SD: 10.5]); 44 completed both treatments; 41 were per protocol subjects. Carbamazepine immediate-release had worse scores compared with LCM for the primary composite neuropsychological outcome (mean difference=0.33 [SD: 1.36], p=0.011) and for the composite EEG score (mean difference=0.92 [SD: 1.77], p=0.003). Secondary analyses across the individual variables revealed that CBZ-IR was statistically worse than LCM on 36% (4/11) of the neuropsychological tests (computerized and noncomputerized) and 0% of the four EEG measures; none favored CBZ-IR. Drug-related AEs occurred more with CBZ-IR (49%) than LCM (22%). Lacosamide had fewer untoward neuropsychological and EEG effects and fewer AEs and AE-related discontinuations than CBZ-IR in healthy subjects. Lacosamide exhibits a favorable cognitive profile. Copyright © 2016 Elsevier Inc. All rights reserved.

High-sensitivity GMR with low coercivity in top-IrMn spin-valves

NASA Astrophysics Data System (ADS)

Liu, H. R.; Qu, B. J.; Ren, T. L.; Liu, L. T.; Xie, H. L.; Li, C. X.; Ku, W. J.

2003-12-01

Top-IrMn spin-valves with a structure of Ta/NiFe/CoFe/Cu/CoFe/IrMn/Ta have been investigated. The spin-valves were deposited by high vacuum DC magnetron sputtering at room temperature. The magnetoresistance ratio reaches 9.12% at room temperature. The coercivity of the free layer and the exchange bias field is 1.04 and 180 Oe, respectively. The maximum sensitivity of the spin-valves is 8.36%/Oe. A reduction of 33.2% of the coercivity was obtained after a 2-min RIE process. Utilizing standard integrated circuit (IC) process, mass production of robust giant magnetoresistance sensors can be achieved with these spin-valve thin films.

Evaluation of the feasibility of switching from immediate release quetiapine to extended release quetiapine fumarate in stable outpatients with schizophrenia.

PubMed

Möller, Hans-Jürgen; Johnson, Sunny; Mateva, Temenuzhka; Brecher, Martin; Svensson, Ola; Miller, Frank; Meulien, Didier

2008-03-01

This double-blind, double-dummy study (D1444C00146) evaluated the efficacy and safety of switching patients with clinically stable schizophrenia from quetiapine immediate release (IR) to the same dose of once-daily extended release quetiapine fumarate (quetiapine XR). Patients received quetiapine IR 400-800 mg/day twice daily for 4 weeks, and were then randomized (2 : 1) to a once-daily equivalent dose of quetiapine XR or maintained on IR for 6 weeks. The primary variable was the proportion of patients who discontinued treatment owing to lack of efficacy or whose Positive and Negative Syndrome Scale scores increased by at least 20% from randomization to any visit. In total, 497 patients were randomized to quetiapine XR (n=331) or IR (n=166). Noninferiority (6% margin; one-sided test, 2.5% significance level) was narrowly missed for the primary efficacy variable for the modified intention-to-treat population (9.1%, quetiapine XR; 7.2%, quetiapine IR; difference 1.86%; 95% confidence interval: -3.78, 6.57; P=0.0431), but was shown for the per-protocol population (5.3%, quetiapine XR; 6.2%, quetiapine IR; difference: -0.83%; 95% confidence interval: -6.75, 3.71; P=0.0017). Serious adverse event incidence was low for quetiapine XR and IR; there were no unexpected adverse events. In conclusion, efficacy was maintained without compromising safety/tolerability when switching patients with stable schizophrenia from twice-daily quetiapine IR to once-daily quetiapine XR (400-800 mg/day).

Cloud-top structure of tornadic storms on 10 April 1979 from rapid scan and stereo satellite observations

NASA Technical Reports Server (NTRS)

Negri, A. J.

1982-01-01

Stereoscopic data from near-synchronous eastern and western GOES satellite 3 min interval visible and IR measurements and ground-based radar are used to examine the Wichita Falls, TX tornado of April, 1979. The visible wavelength scan was at 0.6 micron, while the IR was at 11 microns, and additional IR blackbody temperatures were acquired from the Tiros-N spacecraft. A minimum cloud top temperature of 208 K located the point of tornadogenesis. The cloud top cooling rate was determined to be 7 K/21 min above the tropopause preceding the tornado, while a warm area at 221 K developed downwind at the same time. It was found that temperature differences of 10 K can exist between GOES and Tiros-N anvil top measurements, and reach 20 K in the case of a young thunderstorm.

Luminescence studies of CdS spherical particles via hydrothermal synthesis

NASA Astrophysics Data System (ADS)

Xu, Guo Qin; Liu, Bing; Xu, Shi Jie; Chew, Chwee Har; Chua, Soo Jin; Gana, Leong Ming

2000-06-01

The spherical particles of CdS consisting of nanoparticles (∼100 nm) were synthesized by a hydrothermal process. The particle formation and growth depend on the rate of sulfide-ion generation and diffusion-controlled aggregation of nanoparticles. As demonstrated in the profiles of powder X-ray diffraction, the crystalline phases are governed by the reaction temperature. Photoluminescence studies on CdS particles show two emission bands at the room temperature. The red emission at 680 nm is due to sulfur vacancies, and a new infrared red (IR) emission at 760 nm is attributed to self-activated centers. A red shift of IR band with the decrease of temperature was explained with a configurational coordinate model. The different saturation limits for the red and IR bands are discussed in terms of the formation of donor-acceptor pairs and exciton in CdS particles.

Pressure and temperature dependence of the Ce valence and c -f hybridization gap in Ce T2In5(T =Co ,Rh ,Ir ) heavy-fermion superconductors

NASA Astrophysics Data System (ADS)

Yamaoka, H.; Yamamoto, Y.; Schwier, E. F.; Honda, F.; Zekko, Y.; Ohta, Y.; Lin, J.-F.; Nakatake, M.; Iwasawa, H.; Arita, M.; Shimada, K.; Hiraoka, N.; Ishii, H.; Tsuei, K.-D.; Mizuki, J.

2015-12-01

Pressure- and temperature-induced changes in the Ce valence and c -f hybridization of the Ce115 superconductors have been studied systematically. Resonant x-ray-emission spectroscopy indicated that the increase of the Ce valence with pressure was significant for CeCoIn5, and moderate for CeIr (In0.925Cd0.075)5 . We found no abrupt change of the Ce valence in the Kondo regime for CeIr (In0.925Cd0.075)5 , which suggests that valence fluctuations are unlikely to mediate the superconductivity in this material. X-ray-diffraction results were consistent with the pressure-induced change in the Ce valence. High-resolution photoelectron spectroscopy revealed a temperature-dependent reduction of the spectral intensity at the Fermi level, indicating enhanced c -f hybridization on cooling.

High-resolution fast temperature mapping of a gas turbine combustor simulator with femtosecond infrared laser written fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Walker, Robert B.; Yun, Sangsig; Ding, Huimin; Charbonneau, Michel; Coulas, David; Ramachandran, Nanthan; Mihailov, Stephen J.

2017-02-01

Femtosecond infrared (fs-IR) written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent to the advanced gas turbine engines under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper discusses fabrication and deployment of several fs-IR written FBG arrays, for monitoring the sidewall and exhaust temperature gradients of a gas turbine combustor simulator. Results include: contour plots of measured temperature gradients contrasted with thermocouple data, discussion of deployment strategies and comments on reliability.

An IR Sensor Based Smart System to Approximate Core Body Temperature.

PubMed

Ray, Partha Pratim

2017-08-01

Herein demonstrated experiment studies two methods, namely convection and body resistance, to approximate human core body temperature. The proposed system is highly energy efficient that consumes only 165 mW power and runs on 5 VDC source. The implemented solution employs an IR thermographic sensor of industry grade along with AT Mega 328 breakout board. Ordinarily, the IR sensor is placed 1.5-30 cm away from human forehead (i.e., non-invasive) and measured the raw data in terms of skin and ambient temperature which is then converted using appropriate approximation formula to find out core body temperature. The raw data is plotted, visualized, and stored instantaneously in a local machine by means of two tools such as Makerplot, and JAVA-JAR. The test is performed when human object is in complete rest and after 10 min of walk. Achieved results are compared with the CoreTemp CM-210 sensor (by Terumo, Japan) which is calculated to be 0.7 °F different from the average value of BCT, obtained by the proposed IR sensor system. Upon a slight modification, the presented model can be connected with a remotely placed Internet of Things cloud service, which may be useful to inform and predict the user's core body temperature through a probabilistic view. It is also comprehended that such system can be useful as wearable device to be worn on at the hat attachable way.

Pressure-induced metallization of the halide perovskite (CH 3NH 3)PbI 3

DOE PAGES

Jaffe, Adam; Lin, Yu; Mao, Wendy L.; ...

2017-03-14

We report the metallization of the hybrid perovskite semiconductor (MA)PbI 3 (MA = CH 3NH 3 +) with no apparent structural transition. We tracked its bandgap evolution during compression in diamond-anvil cells using absorption spectroscopy and observed strong absorption over both visible and IR wavelengths at pressures above ca. 56 GPa, suggesting the imminent closure of its optical bandgap. The metallic character of (MA)PbI 3 above 60 GPa was confirmed using both IR reflectivity and variable-temperature dc conductivity measurements. The impressive semiconductor properties of halide perovskites have recently been exploited in a multitude of optoelectronic applications. Meanwhile, the study ofmore » metallic properties in oxide perovskites has revealed diverse electronic phenomena. Importantly, the mild synthetic routes to halide perovskites and the templating effects of the organic cations allow for fine structural control of the inorganic lattice. Lastly, pressure-induced closure of the 1.6 eV bandgap in (MA)PbI3 demonstrates the promise of the continued study of halide perovskites under a range of thermodynamic conditions, toward realizing wholly new electronic properties.« less

Pressure-Induced Metallization of the Halide Perovskite (CH 3 NH 3 )PbI 3

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

Jaffe, Adam; Lin, Yu; Mao, Wendy L.

We report the metallization of the hybrid perovskite semiconductor (MA)PbI3 (MA = CH3NH3+) with no apparent structural transition. We tracked its bandgap evolution during compression in diamond-anvil cells using absorption spectroscopy and observed strong absorption over both visible and IR wavelengths at pressures above ca. 56 GPa, suggesting the imminent closure of its optical bandgap. The metallic character of (MA)PbI3 above 60 GPa was confirmed using both IR reflectivity and variable-temperature dc conductivity measurements. The impressive semiconductor properties of halide perovskites have recently been exploited in a multitude of optoelectronic applications. Meanwhile, the study of metallic properties in oxide perovskitesmore » has revealed diverse electronic phenomena. Importantly, the mild synthetic routes to halide perovskites and the templating effects of the organic cations allow for fine structural control of the inorganic lattice. Pressure-induced closure of the 1.6 eV bandgap in (MA)PbI3 demonstrates the promise of the continued study of halide perovskites under a range of thermodynamic conditions, toward realizing wholly new electronic properties.« less

Pressure-induced metallization of the halide perovskite (CH 3NH 3)PbI 3

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

Jaffe, Adam; Lin, Yu; Mao, Wendy L.

We report the metallization of the hybrid perovskite semiconductor (MA)PbI 3 (MA = CH 3NH 3 +) with no apparent structural transition. We tracked its bandgap evolution during compression in diamond-anvil cells using absorption spectroscopy and observed strong absorption over both visible and IR wavelengths at pressures above ca. 56 GPa, suggesting the imminent closure of its optical bandgap. The metallic character of (MA)PbI 3 above 60 GPa was confirmed using both IR reflectivity and variable-temperature dc conductivity measurements. The impressive semiconductor properties of halide perovskites have recently been exploited in a multitude of optoelectronic applications. Meanwhile, the study ofmore » metallic properties in oxide perovskites has revealed diverse electronic phenomena. Importantly, the mild synthetic routes to halide perovskites and the templating effects of the organic cations allow for fine structural control of the inorganic lattice. Lastly, pressure-induced closure of the 1.6 eV bandgap in (MA)PbI3 demonstrates the promise of the continued study of halide perovskites under a range of thermodynamic conditions, toward realizing wholly new electronic properties.« less

Global structure and composition of the martian atmosphere with SPICAM on Mars express

NASA Astrophysics Data System (ADS)

Bertaux, Jean-Loup; Korablev, O.; Fonteyn, D.; Guibert, S.; Chassefière, E.; Lefèvre, F.; Dimarellis, E.; Dubois, J. P.; Hauchecorne, A.; Cabane, M.; Rannou, P.; Levasseur-Regourd, A. C.; Cernogora, G.; Quémerais, E.; Hermans, C.; Kockarts, G.; Lippens, C.; de Maziere, M.; Moreau, D.; Muller, C.; Neefs, E.; Simon, P. C.; Forget, F.; Hourdin, F.; Talagrand, O.; Moroz, V. I.; Rodin, A.; Sandel, B.; Stern, A.

SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) Light, a light-weight (4.7 kg) UV-IR instrument to be flown on Mars Express orbiter, is dedicated to the study of the atmosphere and ionosphere of Mars. A UV spectrometer (118-320 nm, resolution 0.8 nm) is dedicated to nadir viewing, limb viewing and vertical profiling by stellar and solar occultation (3.8 kg). It addresses key issues about ozone, its coupling with H2O, aerosols, atmospheric vertical temperature structure and ionospheric studies. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO+, and CO2+, and its direct interaction with the solar wind. An IR spectrometer (1.0-1.7 μm, resolution 0.5-1.2 nm) is dedicated primarily to nadir measurements of H2O abundances simultaneously with ozone measured in the UV, and to vertical profiling during solar occultation of H2O, CO2, and aerosols. The SPICAM Light near-IR sensor employs a pioneering technology acousto-optical tunable filter (AOTF), leading to a compact and light design. Overall, SPICAM Light is an ideal candidate for future orbiter studies of Mars, after Mars Express, in order to study the interannual variability of martian atmospheric processes. The potential contribution to a Mars International Reference Atmosphere is clear.

Magnetism and anisotropy of Ir5+ based double perovskites Sr2CoIrO6andSr2FeIrO6

NASA Astrophysics Data System (ADS)

Terzic, Jasminka; Yuan, S. J.; Song, W. H.; Aswartham, S.; Cao, G.

2015-03-01

We report on structural, thermodynamic and transport study of single-crystal double perovskites Sr2CoIrO6andSr2FeIrO6.TheisostructuralSr2CoIrO6andSr2FeIrO6 feature a cubic crystal structure with pentavalent Ir5+(5d4) which are anticipated to have J =0 singlet ground states in the strong spin-orbit coupling limit. Here we observe magnetic coupling between 5d and 3d (Co, Fe) elements, which result in antiferromagnetic order at high temperatures in both double perovskites. Of the two, Sr2CoIrO6 displays antiferromagnetic metallic behavior with a pronounced magnetic anisotropy; in sharp contrast, the isostructural Sr2FeIrO6 exhibits an antiferroamagnetic, insulating ground state without discernible magnetic anisotropy. The data will be discussed and presented with comparisons drawn with similar systems. This work was supported by NSF via Grant DMR 1265162.

The Ionotropic Receptors IR21a and IR25a mediate cool sensing in Drosophila

PubMed Central

Ni, Lina; Klein, Mason; Svec, Kathryn V; Budelli, Gonzalo; Chang, Elaine C; Ferrer, Anggie J; Benton, Richard; Samuel, Aravinthan DT; Garrity, Paul A

2016-01-01

Animals rely on highly sensitive thermoreceptors to seek out optimal temperatures, but the molecular mechanisms of thermosensing are not well understood. The Dorsal Organ Cool Cells (DOCCs) of the Drosophila larva are a set of exceptionally thermosensitive neurons critical for larval cool avoidance. Here, we show that DOCC cool-sensing is mediated by Ionotropic Receptors (IRs), a family of sensory receptors widely studied in invertebrate chemical sensing. We find that two IRs, IR21a and IR25a, are required to mediate DOCC responses to cooling and are required for cool avoidance behavior. Furthermore, we find that ectopic expression of IR21a can confer cool-responsiveness in an Ir25a-dependent manner, suggesting an instructive role for IR21a in thermosensing. Together, these data show that IR family receptors can function together to mediate thermosensation of exquisite sensitivity. DOI: http://dx.doi.org/10.7554/eLife.13254.001 PMID:27126188

Purification, immobilization and characterization of tannase from Penicillium variable.

PubMed

Sharma, Shashi; Agarwal, Lata; Saxena, Rajendra Kumar

2008-05-01

Tannase from Penicillium variable IARI 2031 was purified by a two-step purification strategy comprising of ultra-filtration using 100 kDa molecular weight cutoff and gel-filtration using Sephadex G-200. A purification fold of 135 with 91% yield of tannase was obtained. The enzyme has temperature and pH optima of 50 degrees C and 5 degrees C, respectively. However, the functional temperature range is from 25 to 80 degrees C and functional pH range is from 3.0 to 8.0. This tannase could successfully be immobilized on Amberlite IR where it retains about 85% of the initial catalytic activity even after ninth cycle of its use. Based on the Michaelis-Menten constant (Km) of tannase, tannic acid is the best substrate with Km of 32 mM and Vmax of 1.11 micromol ml(-1)min(-1). Tannase is inhibited by phenyl methyl sulphonyl fluoride (PMSF) and N-ethylmaleimide retaining only 28.1% and 19% residual activity indicating that this enzyme belongs to the class of serine hydrolases. Tannase in both crude and crude lyophilized forms is stable for one year retaining more than 60% residual activity.

Unusual ground states in {R_5T_4X_{10}} (R  =  rare earth; T  =  Rh, Ir; and X  =  Si, Ge, Sn): a review

NASA Astrophysics Data System (ADS)

Ramakrishnan, S.; van Smaalen, Sander

2017-11-01

Rare earth compounds of the type R_5T_4X10 (R  =  rare earth; T  =  Rh, Ir, and X  =  Si, Ge, Sn) display a variety of phase transitions towards exotic states, including charge density waves (CDW), local moment magnetism, antiferromagnetism in the heavy fermion state, superconductivity and giant positive magnetoresistance. They support strongly correlated electron systems. In particular, R 5Ir4 Si10 (R  =  Dy-Lu) exhibit strong coupling CDWs with high transition temperatures, and superconductivity or magnetic ordering at lower temperatures. R_5T4 Ge10 (R  =  Gd-Tm T  =  Co, Rh, Ir) show multiple magnetic transitions with large magnetoresistance below the magnetic transitions. Finally, the light rare earth series R_5T4 Sn10 (R  =  Ce, Pr, Nd; T  =  Rh, Ir) display heavy fermion behaviour (for Ce and Pr) or possess giant positive magnetoresistance (for Nd) at low temperatures. This review provides a comprehensive overview of compounds, crystal structures and phase transitions. This is followed by an in-depth discussion of the mechanisms of the phase transitions and the properties of the ordered states.

Possible Mechanism of Infrared Radiation Reception: The Role of the Temperature Factor

NASA Astrophysics Data System (ADS)

Yachnev, I. L.; Penniyaynen, V. A.; Podzorova, S. A.; Rogachevskii, I. V.; Krylov, B. V.

2018-02-01

The role of the temperature factor in the mechanism of reception of the CO2 laser low-power infrared (IR) radiation (λ = 10.6 μm) by a sensory neuron membrane has been studied. Organotypic embryonic tissue culture has been used to measure and estimate the temperature of a sensory ganglia monolayer exposed to radiation at different energy densities. The effects of tissue exposure to low-power IR radiation have been investigated. It has been found that inhibition of tissue growth by radiation of low energy density (10-14-10-10 J/cm2) is replaced by tissue growth (10-7-10-4 J/cm2), and again followed by inhibition in the range of 0.1-6 J/cm2. A statistically significant specific reaction to nonthermal radiation has been detected at the radiation power density of 3 × 10-10 J/cm2, which is due to activation of the Na+,K+-ATPase transducer function. The mechanisms of interaction of IR radiation with embryonic nerve tissue have been considered. Low-power IR radiation with the wavelength of 10.6 μm has been demonstrated to specifically activate a novel signal transducer function of the sodium pump, which controls the reception of nonthermal IR radiation in the energy density range of 10-14 to 10-10 J/cm2.

Research and Technology Capabilities Available for Partnership, 2007-2008

DTIC Science & Technology

2010-01-01

simulated aircraft environment to measure acoustic and/ or IR radiation and signature. Instrumentation is capable of 96 pressure channels and 105...temperature channels. Mobile Aircraft Infrared Measurement System (AIMS) is field deployable and is used to take full-spectrum IR measurements at our CTF...three phase power. The facility is utilized for the development of visible, IR and RF spectrum sensors/seekers, signature measurement collection of

The prediction of tropopause height from clusters of brightness temperatures and its application in the stratified regression temperature retrievals using microwave and infrared satellite measurements

NASA Technical Reports Server (NTRS)

Munteanu, M. J.; Piraino, P.; Jakubowicz, O.

1984-01-01

A total of 1575 radiosondes and the corresponding simulated brightness temperatures were used in an effort to derive a temperature retrieval based on the clusters of brightness temperatures. The 8 simulated channels, namely, 3 MSU and 5 IR of the TIROS-N satellite are used by the GLAS temperature retrieval method. The 3 MSU and 5 IR brightness temperatures were clustered into 17 cluster groups and a regression for the prediction of the tropopause height in mb was generated. The overall r.m.s. for the tropopause prediction is excellent, namely, around 16 mb for the summer and 23 mb for the winter. The correct cluster of brightness temperatures can be identified 98% of the time by the method of discriminatory classification if it is approximately a normal distribution or, in general, by the method of the nearest neighbor.

Room temperature infrared imaging sensors based on highly purified semiconducting carbon nanotubes.

PubMed

Liu, Yang; Wei, Nan; Zhao, Qingliang; Zhang, Dehui; Wang, Sheng; Peng, Lian-Mao

2015-04-21

High performance infrared (IR) imaging systems usually require expensive cooling systems, which are highly undesirable. Here we report the fabrication and performance characteristics of room temperature carbon nanotube (CNT) IR imaging sensors. The CNT IR imaging sensor is based on aligned semiconducting CNT films with 99% purity, and each pixel or device of the imaging sensor consists of aligned strips of CNT asymmetrically contacted by Sc and Pd. We found that the performance of the device is dependent on the CNT channel length. While short channel devices provide a large photocurrent and a rapid response of about 110 μs, long channel length devices exhibit a low dark current and a high signal-to-noise ratio which are critical for obtaining high detectivity. In total, 36 CNT IR imagers are constructed on a single chip, each consists of 3 × 3 pixel arrays. The demonstrated advantages of constructing a high performance IR system using purified semiconducting CNT aligned films include, among other things, fast response, excellent stability and uniformity, ideal linear photocurrent response, high imaging polarization sensitivity and low power consumption.

Effect of Infrared Blanching on Enzyme Activity and Retention of β-Carotene and Vitamin C in Dried Mango.

PubMed

Guiamba, Isabel R F; Svanberg, Ulf; Ahrné, Lilia

2015-06-01

The objectives of this work were to evaluate infrared (IR) dry blanching in comparison with conventional water blanching prior to hot air drying of mango to inactivate polyphenol oxidase (PPO) and ascorbic acid oxidase (AAO) enzymes, and to study its effect on color change and retention of vitamin C and β-carotene. Mango cylinders were blanched under similar temperature-time conditions either by IR heating or by immersion in a water bath during 2 min at 90 °C (high-temperature-short-time-HTST) or for 10 min at 65 °C (low-temperature-long-time-LTLT). After blanching mango was hot air dried at 70 °C. PPO was completely inactivated during the blanching treatments, but AAO had a moderate remaining activity after LTLT treatment (∼30%) and a low remaining activity after HTST treatment (9% to 15%). A higher retention of vitamin C was observed in mango subjected to IR dry blanching, 88.3 ± 1.0% (HTST) and 69.2 ± 2.9% (LTLT), compared with water blanching, 61.4 ± 5.3% (HTST) and 50.7 ± 9.6% (LTLT). All-trans-β-carotene retention was significantly higher in water blanched dried mango, 93.2 ± 5.2% (LTLT) and 91.4 ± 5.1% (HTST), compared with IR dry blanched, 73.6 ± 3.6% (LTLT) and 76.9 ± 2.9% (HTST). Increased levels of 13-cis-β-carotene isomer were detected only in IR dry blanched mango, and the corresponding dried mango also had a slightly darker color. IR blanching of mango prior to drying can improve the retention of vitamin C, but not the retention of carotenoids, which showed to be more dependent on the temperature than the blanching process. A reduction of drying time was observed in LTLT IR-blanching mango. © 2015 Institute of Food Technologists®

Glass formation and short-range order structures in the BaS + La 2S 3 + GeS 2 system

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

Roth, Josh R.; Martin, Steve W.; Ballato, John

Here, infrared (IR) optical materials have enabled a broad range of optical sensing and measurement applications in the mid-wave and long-wave IR. Many IR transmitting glasses are based on covalently-bonded selenides and tellurides, such as As 2Se 3 and GeTe 2, which typically have relatively low glass transition temperatures ( T g) on the order of 200 to 350 °C. Many applications have working temperatures above the T g of these materials, which compels the development of new IR materials. This work studies the underlying short-range order (SRO) structure and glass formability of a new family of ionically-bonded sulfide glasses,more » xBaS + yLa 2S 3 + (1 – x – y)GeS 2, to develop high T g optical materials with a broad IR transmission range. These sulfide glasses were produced by melting sulfide materials inside evacuated and sealed carbon-coated silica ampoules at 1150 °C for 12 h and quenching to room temperature to form glass. Glass samples were then characterized by IR and Raman spectroscopies and differential thermal analysis (DTA). It was found that by increasing the modifier concentration, the predominantly Ge 4 SRO units, the superscript defines the number of bridging sulfur (BS) ions in the tetrahedral network found in GeS 2 glasses, are ultimately converted to Ge 0 units at >40 mol% network modifier content through the generation of non-bridging sulfur (NBS) ions. These molecular ionic units still form a glassy network, with some of the highest reported T g values to date for a pure sulfide glass. This suggests that this composition has strong ionic bonds between negatively-charged tetrahedral SRO units and the positively-charged modifier cations. While the glass network is depolymerized in the high modifier content glasses though the formation of a high concentration of molecular ionic Ge 0 SRO groups, they are, nevertheless, homogeneous glassy materials that exhibit the largest T g and Δ T (difference between crystallization temperature, T c, and T g) values of glasses in this system, making them the optimal glasses for high T g IR optical components, including, potentially, refractory IR optical fibers.« less

Glass formation and short-range order structures in the BaS + La 2S 3 + GeS 2 system

DOE PAGES

Roth, Josh R.; Martin, Steve W.; Ballato, John; ...

2018-06-01

Here, infrared (IR) optical materials have enabled a broad range of optical sensing and measurement applications in the mid-wave and long-wave IR. Many IR transmitting glasses are based on covalently-bonded selenides and tellurides, such as As 2Se 3 and GeTe 2, which typically have relatively low glass transition temperatures ( T g) on the order of 200 to 350 °C. Many applications have working temperatures above the T g of these materials, which compels the development of new IR materials. This work studies the underlying short-range order (SRO) structure and glass formability of a new family of ionically-bonded sulfide glasses,more » xBaS + yLa 2S 3 + (1 – x – y)GeS 2, to develop high T g optical materials with a broad IR transmission range. These sulfide glasses were produced by melting sulfide materials inside evacuated and sealed carbon-coated silica ampoules at 1150 °C for 12 h and quenching to room temperature to form glass. Glass samples were then characterized by IR and Raman spectroscopies and differential thermal analysis (DTA). It was found that by increasing the modifier concentration, the predominantly Ge 4 SRO units, the superscript defines the number of bridging sulfur (BS) ions in the tetrahedral network found in GeS 2 glasses, are ultimately converted to Ge 0 units at >40 mol% network modifier content through the generation of non-bridging sulfur (NBS) ions. These molecular ionic units still form a glassy network, with some of the highest reported T g values to date for a pure sulfide glass. This suggests that this composition has strong ionic bonds between negatively-charged tetrahedral SRO units and the positively-charged modifier cations. While the glass network is depolymerized in the high modifier content glasses though the formation of a high concentration of molecular ionic Ge 0 SRO groups, they are, nevertheless, homogeneous glassy materials that exhibit the largest T g and Δ T (difference between crystallization temperature, T c, and T g) values of glasses in this system, making them the optimal glasses for high T g IR optical components, including, potentially, refractory IR optical fibers.« less

Qualification of security printing features

NASA Astrophysics Data System (ADS)

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

2006-02-01

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

Assessment of a Technique for Estimating Total Column Water Vapor Using Measurements of the Infrared Sky Temperature

NASA Technical Reports Server (NTRS)

Merceret, Francis J.; Huddleston, Lisa L.

2014-01-01

A method for estimating the integrated precipitable water (IPW) content of the atmosphere using measurements of indicated infrared zenith sky temperature was validated over east-central Florida. The method uses inexpensive, commercial off the shelf, hand-held infrared thermometers (IRT). Two such IRTs were obtained from a commercial vendor, calibrated against several laboratory reference sources at KSC, and used to make IR zenith sky temperature measurements in the vicinity of KSC and Cape Canaveral Air Force Station (CCAFS). The calibration and comparison data showed that these inexpensive IRTs provided reliable, stable IR temperature measurements that were well correlated with the NOAA IPW observations.

Infrared and Raman spectroscopy and quantum chemistry calculation studies of C H⋯O hydrogen bondings and thermal behavior of biodegradable polyhydroxyalkanoate

NASA Astrophysics Data System (ADS)

Sato, Harumi; Dybal, Jiří; Murakami, Rumi; Noda, Isao; Ozaki, Yukihiro

2005-06-01

This review paper reports infrared (IR) and Raman spectroscopy and quantum chemistry calculation studies of C-H⋯O hydrogen bondings and thermal behavior of biodegradable polyhydroxyalkanoates. IR and Raman spectra were measured for poly(3-hydroxybutyrate) (PHB) and a new type of bacterial copolyester, poly(3-hydroxybutyrate- co-3-hydroxyhexanoate), P(HB- co-HHx) (HHx=12 mol%) over a temperature range of 20 °C to higher temperatures (PHB, 200 °C; HHx=12 mol%, 140 °C) to explore their structure and thermal behavior. One of bands due to the CH 3 asymmetric stretching modes appears near 3010 cm -1 in the IR and Raman spectra of PHB and P(HB- co-HHx) at 20 °C. These frequencies of IR and Raman CH 3 asymmetric stretching bands are much higher than usual. These anomalous frequencies of the CH 3 asymmetric stretching bands together with the X-ray crystallographic structure of PHB have suggested that there is an inter- or intra-molecular C-H⋯O hydrogen bond between the C dbnd6 O group in one helical structure and the CH 3 group in the other helical structure in PHB and P(HB- co-HHx). The quantum chemical calculation of model compounds of PHB also has suggested the existence of C-H⋯O hydrogen bonds in PHB and P(HB- co-HHx). It is very likely that a chain of C-H⋯O hydrogen bond pairs link two parallel helical structures in the crystalline parts. The temperature-dependent IR and Raman spectral variations have revealed that the crystallinity of P(HB- co-HHx) (HHx=12 mol%) decreases gradually from a fairly low temperature (about 60 °C), while the crystallinity of PHB remains almost unchanged until just below its melting temperature. It has also been found from the IR and Raman studies that for both PHB and P(HB- co-HHx) the weakening of the C-H⋯O hydrogen bonds starts from just above room temperature, but the deformation of helical structures occurs after the weakening of the C-H⋯O hydrogen bonds advances to some extent.

C/2013 R1 (Lovejoy) at IR wavelengths and the variability of CO abundances among Oort Cloud comets

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

Paganini, L.; Mumma, M. J.; Villanueva, G. L.

2014-08-20

We report production rates, rotational temperatures, and related parameters for gases in C/2013 R1 (Lovejoy) using the Near InfraRed SPECtrometer at the Keck Observatory, on six UT dates spanning heliocentric distances (R{sub h} ) that decreased from 1.35 AU to 1.16 AU (pre-perihelion). We quantified nine gaseous species (H{sub 2}O, OH*, CO, CH{sub 4}, HCN, C{sub 2}H{sub 6}, CH{sub 3}OH, NH{sub 3}, and NH{sub 2}) and obtained upper limits for two others (C{sub 2}H{sub 2} and H{sub 2}CO). Compared with organics-normal comets, our results reveal highly enriched CO, (at most) slightly enriched CH{sub 3}OH, C{sub 2}H{sub 6}, and HCN, andmore » CH{sub 4} consistent with {sup n}ormal{sup ,} yet depleted, NH{sub 3}, C{sub 2}H{sub 2}, and H{sub 2}CO. Rotational temperatures increased from ∼50 K to ∼70 K with decreasing R{sub h} , following a power law in R{sub h} of –2.0 ± 0.2, while the water production rate increased from 1.0 to 3.9 × 10{sup 28} molecules s{sup –1}, following a power law in R{sub h} of –4.7 ± 0.9. The ortho-para ratio for H{sub 2}O was 3.01 ± 0.49, corresponding to spin temperatures (T {sub spin}) ≥ 29 K (at the 1σ level). The observed spatial profiles for these emissions showed complex structures, possibly tied to nucleus rotation, although the cadence of our observations limits any definitive conclusions. The retrieved CO abundance in Lovejoy is more than twice the median value for comets in our IR survey, suggesting this comet is enriched in CO. We discuss the enriched value for CO in comet C/2013 R1 in terms of the variability of CO among Oort Cloud comets.« less

Design and Calibration of a Dispersive Imaging Spectrometer Adaptor for a Fast IR Camera on NSTX-U

NASA Astrophysics Data System (ADS)

Reksoatmodjo, Richard; Gray, Travis; Princeton Plasma Physics Laboratory Team

2017-10-01

A dispersive spectrometer adaptor was designed, constructed and calibrated for use on a fast infrared camera employed to measure temperatures on the lower divertor tiles of the NSTX-U tokamak. This adaptor efficiently and evenly filters and distributes long-wavelength infrared photons between 8.0 and 12.0 microns across the 128x128 pixel detector of the fast IR camera. By determining the width of these separated wavelength bands across the camera detector, and then determining the corresponding average photon count for each photon wavelength, a very accurate measurement of the temperature, and thus heat flux, of the divertor tiles can be calculated using Plank's law. This approach of designing an exterior dispersive adaptor for the fast IR camera allows accurate temperature measurements to be made of materials with unknown emissivity. Further, the relative simplicity and affordability of this adaptor design provides an attractive option over more expensive, slower, dispersive IR camera systems. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No. DE-AC02-09CH11466.

Low carrier semiconductor like behavior in Lu3Ir4Ge13 single crystal

NASA Astrophysics Data System (ADS)

Kumar, Anil; Matteppanavar, Shidaling; Thamizhavel, A.; Ramakrishnan, S.

2018-04-01

Single crystal of Lu3Ir4Ge13 crystallizing in the Yb3Rh4Sn13-type cubic crystal structure has been grown by Czochralski method in a tetra-arc furnace. In this paper we report on the crystal structure, magnetic and transport properties of Lu3Ir4Ge13. The analysis of the powder x-ray diffraction (XRD) studies revealed that Lu3Ir4Ge13 crystallizes in a cubic structure with the space group Pm-3n, no. 223. The lattice parameter was obtained from the Rietveld refinement of the room temperature XRD data which amounts to 8.904 (3) Å with low R factors. The temperature dependence of the resistivity exhibited semiconductor like behavior till 1.8 K, with a broad hump around 15 - 62 K. This hump was observed in both warming and cooling cycle with a very small hysteresis, it may be due to the existence of structural transition from high - low symmetry. The temperature dependent magnetization data shows the diamagnetic behavior with an anomaly around 70 K, which is well supported by the derivative of resistivity data.

Physics of the infrared spectrum

NASA Technical Reports Server (NTRS)

Deming, Drake; Jennings, Donald E.; Jefferies, John; Lindsey, Charles

1991-01-01

The IR bandpass is attractive for solar magnetic field studies in virtue of the proportionality to wavelength of the ratio of Zeeman splitting to line width. The large Zeeman splitting and optical thinness of the 12-micron observations render them especially useful for vector magnetic field derivations. The IR continuum, and many IR spectral lines, are formed in LTE and are useful in studies of the temperature structure of the solar atmosphere from the deepest observable photospheric layers to chromospheric altitudes. The far-IR continuum is an excellent thermometer for the upper photosphere and chromosphere.

Operational satellites and the global monitoring of snow and ice

NASA Technical Reports Server (NTRS)

Walsh, John E.

1991-01-01

The altitudinal dependence of the global warming projected by global climate models is at least partially attributable to the albedo-temperature feedback involving snow and ice, which must be regarded as key variables in the monitoring for global change. Statistical analyses of data from IR and microwave sensors monitoring the areal coverage and extent of sea ice have led to mixed conclusions about recent trends of hemisphere sea ice coverage. Seasonal snow cover has been mapped for over 20 years by NOAA/NESDIS on the basis of imagery from a variety of satellite sensors. Multichannel passive microwave data show some promise for the routine monitoring of snow depth over unforested land areas.

Infrared absorption spectra of molecular crystals: Possible evidence for small-polaron formation?

NASA Astrophysics Data System (ADS)

Pržulj, Željko; Čevizović, Dalibor; Zeković, Slobodan; Ivić, Zoran

2008-09-01

The temperature dependence of the position of the so-called anomalous band peaked at 1650cm in the IR-absorption spectrum of crystalline acetanilide (ACN) is theoretically investigated within the small-polaron theory. Its pronounced shift towards the position of the normal band is predicted with the rise of temperature. Interpretation of the IR-absorption spectra in terms of small-polaron model has been critically assessed on the basis of these results.

Methanol-Water Aqueous-Phase Reforming with the Assistance of Dehydrogenases at Near-Room Temperature.

PubMed

Shen, Yangbin; Zhan, Yulu; Li, Shuping; Ning, Fandi; Du, Ying; Huang, Yunjie; He, Ting; Zhou, Xiaochun

2018-03-09

As an excellent hydrogen-storage medium, methanol has many advantages, such as high hydrogen content (12.6 wt %), low cost, and availability from biomass or photocatalysis. However, conventional methanol-water reforming usually proceeds at high temperatures. In this research, we successfully designed a new effective strategy to generate hydrogen from methanol at near-room temperature. The strategy involved two main processes: CH 3 OH→HCOOH→H 2 and NADH→HCOOH→H 2 . The first process (CH 3 OH→HCOOH→H 2 ) was performed by an alcohol dehydrogenase (ADH), an aldehyde dehydrogenase (ALDH), and an Ir catalyst. The second procedure (NADH→HCOOH→H 2 ) was performed by formate dehydrogenase (FDH) and the Ir catalyst. The Ir catalyst used was a previously reported polymer complex catalyst [Cp*IrCl 2 (ppy); Cp*=pentamethylcyclopentadienyl, ppy=polypyrrole] with high catalytic activity for the decomposition of formic acid at room temperature and is compatible with enzymes, coenzymes, and poisoning chemicals. Our results revealed that the optimum hydrogen generation rate could reach up to 17.8 μmol h -1  g cat -1 under weak basic conditions at 30 °C. This will have high impact on hydrogen storage, production, and applications and should also provide new inspiration for hydrogen generation from methanol. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrothermal synthesis, crystal structure, luminescent and magnetic properties of a new mononuclear GdIII coordination complex

NASA Astrophysics Data System (ADS)

Coban, Mustafa Burak

2018-06-01

A new GdIII coordination complex, {[Gd(2-stp)2(H2O)6].2(4,4'-bipy).4(H2O)}, complex 1, (2-stp = 2-sulfoterephthalate anion and 4,4'-bipy = 4,4'-bipyridine), has been synthesized by hydrothermal method and characterized by elemental analysis, solid state UV-Vis and FT-IR spectroscopy, single-crystal X-ray diffraction, solid state photoluminescence and variable-temperature magnetic measurements. The crystal structure determination shows that GdIII ions are eight coordinated and adopt a distorted square-antiprismatic geometry. Molecules interacting through intra- and intermolecular (O-H⋯O, O-H⋯N) hydrogen bonds in complex 1, give rise to 3D hydrogen bonded structure and the discrete lattice 4,4'-bipy molecules occupy the channel of the 3D structure. π-π stacking interactions also exist 4,4'-bipy-4,4'-bipy and 4,4'-bipy-2-stp molecule rings in 3D structures. Additionally, solid state photoluminescence properties of complex 1 at room temperature have been investigated. Under the excitation of UV light (at 349 nm), the complex 1 exhibited green emissions (at 505 nm) of GdIII ion in the visible region. Furthermore, Variable-temperature magnetic susceptibility and isothermal magnetization as function of external magnetic field studies reveal that complex 1 displays possible antiferromagnetic interaction.

Distinct combinations of variant ionotropic glutamate receptors mediate thermosensation and hygrosensation in Drosophila

PubMed Central

Knecht, Zachary A; Silbering, Ana F; Ni, Lina; Klein, Mason; Budelli, Gonzalo; Bell, Rati; Abuin, Liliane; Ferrer, Anggie J; Samuel, Aravinthan DT; Benton, Richard; Garrity, Paul A

2016-01-01

Ionotropic Receptors (IRs) are a large subfamily of variant ionotropic glutamate receptors present across Protostomia. While these receptors are most extensively studied for their roles in chemosensory detection, recent work has implicated two family members, IR21a and IR25a, in thermosensation in Drosophila. Here we characterize one of the most evolutionarily deeply conserved receptors, IR93a, and show that it is co-expressed and functions with IR21a and IR25a to mediate physiological and behavioral responses to cool temperatures. IR93a is also co-expressed with IR25a and a distinct receptor, IR40a, in a discrete population of sensory neurons in the sacculus, a multi-chambered pocket within the antenna. We demonstrate that this combination of receptors is required for neuronal responses to dry air and behavioral discrimination of humidity differences. Our results identify IR93a as a common component of molecularly and cellularly distinct IR pathways important for thermosensation and hygrosensation in insects. DOI: http://dx.doi.org/10.7554/eLife.17879.001 PMID:27656904

Long-term Variability of H2CO Masers in Star-forming Regions

NASA Astrophysics Data System (ADS)

Andreev, N.; Araya, E. D.; Hoffman, I. M.; Hofner, P.; Kurtz, S.; Linz, H.; Olmi, L.; Lorran-Costa, I.

2017-10-01

We present results of a multi-epoch monitoring program on variability of 6 cm formaldehyde (H2CO) masers in the massive star-forming region NGC 7538 IRS 1 from 2008 to 2015, conducted with the Green Bank Telescope, the Westerbork Radio Telescope , and the Very Large Array. We found that the similar variability behaviors of the two formaldehyde maser velocity components in NGC 7538 IRS 1 (which was pointed out by Araya and collaborators in 2007) have continued. The possibility that the variability is caused by changes in the maser amplification path in regions with similar morphology and kinematics is discussed. We also observed 12.2 GHz methanol and 22.2 GHz water masers toward NGC 7538 IRS 1. The brightest maser components of CH3OH and H2O species show a decrease in flux density as a function of time. The brightest H2CO maser component also shows a decrease in flux density and has a similar LSR velocity to the brightest H2O and 12.2 GHz CH3OH masers. The line parameters of radio recombination lines and the 20.17 and 20.97 GHz CH3OH transitions in NGC 7538 IRS 1 are also reported. In addition, we observed five other 6 cm formaldehyde maser regions. We found no evidence of significant variability of the 6 cm masers in these regions with respect to previous observations, the only possible exception being the maser in G29.96-0.02. All six sources were also observed in the {{{H}}}213{CO} isotopologue transition of the 6 cm H2CO line; {{{H}}}213{CO} absorption was detected in five of the sources. Estimated column density ratios [{{{H}}}212{CO}]/[{{{H}}}213{CO}] are reported.

Temperature resolution enhancing of commercially available IR camera using computer processing

NASA Astrophysics Data System (ADS)

Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

2015-09-01

As it is well-known, application of the passive THz camera for the security problems is very promising way. It allows seeing concealed object without contact with a person and this camera is non-dangerous for a person. Using such THz camera, one can see a temperature difference on the human skin if this difference is caused by different temperatures inside the body. Because the passive THz camera is very expensive, we try to use the IR camera for observing of such phenomenon. We use a computer code that is available for treatment of the images captured by commercially available IR camera, manufactured by Flir Corp. Using this code we demonstrate clearly changing of human body skin temperature induced by water drinking. Nevertheless, in some cases it is necessary to use additional computer processing to show clearly changing of human body temperature. One of these approaches is developed by us. We believe that we increase ten times (or more) the temperature resolution of such camera. Carried out experiments can be used for solving the counter-terrorism problem and for medicine problems solving. Shown phenomenon is very important for the detection of forbidden objects and substances concealed inside the human body using non-destructive control without X-ray application. Early we have demonstrated such possibility using THz radiation.

Temperature dependence of exchange bias in (NiFe/IrMn)n multilayer films studied through static and dynamic techniques

NASA Astrophysics Data System (ADS)

Adams, Daniel J.; Khanal, Shankar; Khan, Mohammad Asif; Maksymov, Artur; Spinu, Leonard

2018-05-01

The in-plane temperature dependence of exchange bias was studied through both dc magnetometry and ferromagnetic resonance spectroscopy in a series of [NiFe/IrMn]n multilayer films, where n is the number of layer repetitions. Major hysteresis loops were recorded in the temperature range of 300 K to 2 K to reveal the effect of temperature on the exchange bias in the static regime while temperature-dependent continuous-wave ferromagnetic resonance for frequencies from 3 to 16 GHz was used to determine the exchange bias dynamically. Strong divergence between the values of exchange bias determined using the two different types of measurements as well as a peak in temperature dependence of the resonance linewidth were observed. These results are explained in terms of the slow-relaxer mechanism.

Low temperature IR spectroscopic study of torsional vibrations of taurine

NASA Astrophysics Data System (ADS)

Bajaj, Naini; Bhatt, Himal; Vishwakarma, S. R.; Thomas, Susy; Murli, C.; Deo, M. N.

2018-04-01

The hydrogen bonding network in amino acids can give information about the structural stability under varying thermodynamic conditions such as temperature and pressure. We have carried out low temperature IR spectroscopic studies on Taurine, an amino acid with various bio-chemical applications in physiology and synthesis, in order to observe the behaviour of torsional modes, i.e. τ(CSH) and τ(NH3), which are very sensitive to the hydrogen bonding interactions. It was observed that the CSH torsional mode showed splitting at low temperature of nearly 250 K and the bandwidth shows linear temperature dependence, which can be attributed to anharmonicity. Another torsional mode, τ(NH3) showed no splitting, but the bandwidth has non-linear temperature dependence. This can be due to orientational changes at low temperature. These observations are strong evidences for a hydrogen bond reorientation induced phase transition at 250 K.

Higher glucose, insulin and insulin resistance (HOMA-IR) in childhood predict adverse cardiovascular risk in early adulthood: the Pune Children's Study.

PubMed

Yajnik, Chittaranjan S; Katre, Prachi A; Joshi, Suyog M; Kumaran, Kalyanaraman; Bhat, Dattatray S; Lubree, Himangi G; Memane, Nilam; Kinare, Arun S; Pandit, Anand N; Bhave, Sheila A; Bavdekar, Ashish; Fall, Caroline H D

2015-07-01

The Pune Children's Study aimed to test whether glucose and insulin measurements in childhood predict cardiovascular risk factors in young adulthood. We followed up 357 participants (75% follow-up) at 21 years of age who had undergone detailed measurements at 8 years of age (glucose, insulin, HOMA-IR and other indices). Oral glucose tolerance, anthropometry, plasma lipids, BP, carotid intima-media thickness (IMT) and arterial pulse wave velocity (PWV) were measured at 21 years. Higher fasting glucose, insulin and HOMA-IR at 8 years predicted higher glucose, insulin, HOMA-IR, BP, lipids and IMT at 21 years. A 1 SD change in 8 year variables was associated with a 0.10-0.27 SD change at 21 years independently of obesity/adiposity at 8 years of age. A greater rise in glucose-insulin variables between 8 and 21 years was associated with higher cardiovascular risk factors, including PWV. Participants whose HOMA-IR measurement remained in the highest quartile (n = 31) had a more adverse cardiovascular risk profile compared with those whose HOMA-IR measurement remained in the lowest quartile (n = 28). Prepubertal glucose-insulin metabolism is associated with adult cardiovascular risk and markers of atherosclerosis. Our results support interventions to improve glucose-insulin metabolism in childhood to reduce cardiovascular risk in later life.

Technical note: Assessment of an alternative technique for measuring body temperature in pigs.

PubMed

Petry, A; McGilvray, W; Rakhshandeh, A R; Rakhshandeh, A

2017-07-01

Core body temperature (CBT) is one of the main vital signs that is used to evaluate the health status of pigs. The most common and feasible method for assessing CBT in pigs is rectal temperature (RT). Obtaining RT is stressful for animals, may generate inaccurate results, and has the risk of spreading disease. Infrared imaging (IR) thermography of the body of pigs may be a safer and less stressful alternative to RT. The objective of the current study was to evaluate the efficacy of using IR as an alternative for monitoring CBT in pigs. Twenty-three gilts (30.5 ± 5.62 kg BW) were housed in metabolism crates in an environmentally controlled facility and fed an 860 g/d grower diet. After 4 d of adaptation, the febrile response was induced by intramuscular injection of lipopolysaccharide (LPS; 25 µg/kg BW). Each pig's body temperature was recorded at 0, 2, 4, 6, 8, 10, and 24 h after LPS challenge using the following 3 methods: 1) RT, 2) IR of the eye and ear, and 3) CBT using an orally administered digital temperature sensor. Statistical analysis was performed in a completely randomized design in SAS using Mixed, Correlation, and Regression procedures. Relative to time 0 h, LPS increased the eye temperature, CBT, and RT by 0.92, 1.32, and 1.48°C, respectively ( < 0.01), but had no significant effect on ear temperature. Eye temperature, RT, and CBT, but not ear temperature, were highly correlated ( ≥ 0.96) during the course of the study ( < 0.01). Estimated regression parameters (α and β) for predicting CBT using eye temperature were -28.2 ± 8.70 and 1.76 ± 0.221, respectively, and for RT were -24.5 ± 7.69 and 1.65 ± 0.196, respectively ( ≥ 0.96; 95% confidence interval). Collectively, these results indicated a strong relationship between eye temperature, RT, and CBT in pigs. Therefore, IR of the eye can be used as a precise, noncontact alternative to RT measurements for monitoring CBT in swine.

ATR-IR study of skin components: Lipids, proteins and water. Part I: Temperature effect

NASA Astrophysics Data System (ADS)

Olsztyńska-Janus, S.; Pietruszka, A.; Kiełbowicz, Z.; Czarnecki, M. A.

2018-01-01

In this work we report the studies of the effect of temperature on skin components, such as lipids, proteins and water. Modifications of lipids structure induced by increasing temperature (from 20 to 90 °C) have been studied using ATR-IR (Attenuated Total Reflectance Infrared) spectroscopy, which is a powerful tool for characterization of the molecular structure and properties of tissues, such as skin. Due to the small depth of penetration (0.6-5.6 μm), ATR-IR spectroscopy probes only the outermost layer of the skin, i.e. the stratum corneum (SC). The assignment of main spectral features of skin components allows for the determination of phase transitions from the temperature dependencies of band intensities [e.g. νas(CH2) and νs(CH2)]. The phase transitions were determined by using two methods: the first one was based on the first derivative of the Boltzmann function and the second one employed tangent lines of sigmoidal, aforementioned dependencies. The phase transitions in lipids were correlated with modifications of the structure of water and proteins.

AIRS-only Product on Giovanni for Exploring Up-to-date AIRS Observation and Comparing with AIRS+AMSU Product

NASA Astrophysics Data System (ADS)

Ding, F.; Hearty, T. J., III; Theobald, M.; Vollmer, B.; Wei, J.

2017-12-01

The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) has been the home of processing, archiving, and distribution services for the Atmospheric Infrared Sounder (AIRS) mission since its launch in 2002 for the global observations of the atmospheric state. Giovanni, a web-based application developed by the GES DISC, provides a simple and intuitive way to visualize, analyze, and access vast amounts of Earth science remote sensing data without having to download the data. Most important variables, including temperature and humidity profiles, outgoing longwave radiation, cloud properties, and trace gases, from version 6 AIRS product are available on Giovanni. The AIRS is an instrument suite comprised of a hyperspectral infrared instrument AIRS and two multichannel microwave instruments, the Advanced Microwave Sounding Unit (AMSU) and the Humidity Sounder for Brazil (HSB). As the HSB ceased operation in very early stage of AIRS mission, the AIRS project operates two parallel retrieval algorithms: one using both IR and MW measurements (AIRS+AMSU) and the other using only IR measurements (AIRS-only) for the most time of the mission. The AIRS+AMSU product is better and the variables on Giovanni are from it. However, the generation of AIRS+AMSU product has been suspended since the AMSU instrument anomaly occurred in late 2016. To continue exploring up-to-date AIRS observations, the same set of variables from the AIRS-only product are added on Giovanni by the GES DSIC. This will also support the comparison of AIRS-only with AIRS+AMSU retrievals. In the presentation, we will demonstrate the visualization of AIRS-only product and the plots/statistics of comparison with AIRS+AMSU product using Giovanni.

AIRS-Only Product in Giovanni for Exploring Up-to-Date AIRS Observation and Comparing with AIRS+AMSU Product

NASA Technical Reports Server (NTRS)

Ding, Feng; Hearty, Thomas J.; Theobald, Michael; Vollmer, Bruce; Wei, Jennifer

2017-01-01

The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) has been the home of processing, archiving, and distribution services for the Atmospheric Infrared Sounder (AIRS) mission since its launch in 2002 for global observations of the atmospheric state. Giovanni, a Web-based application developed by the GES DISC, provides a simple and intuitive way to visualize, analyze, and access vast amounts of Earth science remote sensing data without having to download the data. Most important AIRS variables, including temperature and humidity profiles, outgoing longwave radiation, cloud properties, and trace gases, are available in Giovanni. AIRS is an instrument suite comprised of a hyperspectral infrared instrument (AIRS) and two multichannel microwave instruments, the Advanced Microwave Sounding Unit (AMSU) and the Humidity Sounder for Brazil (HSB). As HSB ceased operation in the very early stages of the AIRS mission, the AIRS project operates two parallel retrieval algorithms: one using both IR and MW measurements (AIRS+AMSU) and the other using only IR measurements (AIRS-only), which covers most of the mission duration. The AIRS+AMSU product is better quality, and the variables in Giovanni are from this product. However, generation of the AIRS+AMSU product has been suspended since the AMSU instrument anomaly occurred in late September 2016. To continue exploring up-to-date AIRS observations, the same set of variables from the AIRS-only product have been added to Giovanni by the GES DSIC. This will also support comparison of AIRS-only with AIRS+AMSU retrievals. In this presentation, we demonstrate the visualization of the AIRS-only product and plots/statistics of comparison with AIRS+AMSU product using Giovanni.

Electron paramagnetic resonance and FT-IR spectroscopic studies of glycine anhydride and betaine hydrochloride

NASA Astrophysics Data System (ADS)

Halim Başkan, M.; Kartal, Zeki; Aydın, Murat

2015-12-01

Gamma irradiated powders of glycine anhydride and betaine hydrochloride have been investigated at room temperature by electron paramagnetic resonance (EPR). In these compounds, the observed paramagnetic species were attributed to the R1 and R2 radicals, respectively. It was determined that the free electron interacted with environmental protons and 14N nucleus in both radicals. The EPR spectra of gamma irradiated powder samples remained unchanged at room temperature for two weeks after irradiation. Also, the Fourier Transform Infrared (FT-IR), FT-Raman and thermal analyses of both compounds were investigated. The functional groups in the molecular structures of glycine anhydride and betaine hydrochloride were identified by vibrational spectroscopies (FT-IR and FT-Raman).

Thermal effectiveness of different IR radiators employed in rheumatoid hand therapy as assessed by thermovisual examination.

PubMed

Rutkowski, Radosław; Straburzyńska-Lupa, Anna; Korman, Paweł; Romanowski, Wojciech; Gizińska, Małgorzata

2011-01-01

We conducted a thermovisual comparison of mean hand surface temperature changes upon local heating with two different IR sources. Sixty-six patients with rheumatoid arthritis (47 women and 19 men; average age, 56.1 ± 8.6 years) were subjected to topical heat therapy for one hand with either the standard IR radiator (SIR) or the water filter IRA (wIRA). The surface temperature of the dorsal side of both hands was measured, and thermal images were taken before and up to 2 h after treatment. At 1 min after treatment, SIR application increased the surface skin temperature of the heated hand from 31.5 ± 1.9 to 35.0 ± 1.9 °C (P<0.05), while wIRA increased it from 32.1 ± 1.6 to 34.2 ± 1.1 °C (P<0.05). Constant decline in temperature was observed immediately after treatment, with the temperatures reaching baseline in about 30 and 120 min after wIRA and SIR treatment, respectively. Similar temperature changes were observed in the heated hands for wIRA and SIR, except at 1 min after treatment. Changes in the untreated hands indicated contralateral reaction. The temperature of the warmed hand showed a correlation to the body mass index. © 2011 The Authors. Photochemistry and Photobiology © 2011 The American Society of Photobiology.

X-ray scattering study of pyrochlore iridates: Crystal structure, electronic, and magnetic excitations

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

Clancy, J. P.; Gretarsson, H.; Lee, E. K. H.

2016-07-06

We have investigated the structural, electronic, and magnetic properties of the pyrochlore iridates Eu 2Ir 2O 7 and Pr 2Ir 2O 7 using a combination of resonant elastic x-ray scattering, x-ray powder diffraction, and resonant inelastic x-ray scattering (RIXS). The structural parameters of Eu 2Ir 2O 7 have been examined as a function of temperature and applied pressure, with a particular emphasis on regions of the phase diagram where electronic and magnetic phase transitions have been reported. We find no evidence of crystal symmetry change over the range of temperatures (~6 to 300 K) and pressures (~0.1 to 17 GPa)more » studied. We have also investigated the electronic and magnetic excitations in single-crystal samples of Eu 2Ir 2O 7 and Pr 2Ir 2O 7 using high-resolution Ir L- 3-edge RIXS. In spite of very different ground state properties, we find that these materials exhibit qualitatively similar excitation spectra, with crystal field excitations at ~3-5 eV, spin-orbit excitations at ~ 0.5-1 eV, and broad low-lying excitations below ~0.15 eV. In single-crystal samples of "Eu-rich" Eu 2Ir 2O 7 (found to possess an actual stoichiometry of Eu 2.18Ir 1.82O 7.06) we observe highly damped magnetic excitations at ~45 meV, which display significant momentum dependence. Here, we compare these results with recent dynamical structure factor calculations« less

The effect of convection on infrared detection by antennal warm cells in the bloodsucking bug Rhodnius prolixus

PubMed Central

Tichy, Harald

2015-01-01

Previous work revealed that bloodsucking bugs can discriminate between oscillating changes in infrared (IR) radiation and air temperature (T) using two types of warm cells located in peg-in-pit sensilla and tapered hairs (Zopf LM, Lazzari CR, Tichy H. J Neurophysiol 111: 1341–1349, 2014). These two stimuli are encoded and discriminated by the response quotient of the two warm cell types. IR radiation stimulates the warm cell in the peg-in-pit sensillum more strongly than that in the tapered hair. T stimuli evoke the reverse responses; they stimulate the latter more strongly than the former. In nature, IR and T cues are always present with certain radiation intensities and air temperatures, here referred to as background IR radiation and background T. In this article, we found that the response quotient permits the discrimination of IR and T oscillations even in the presence of different backgrounds. We show that the two warm cells respond well to IR oscillations if the background T operates by natural convection but poorly at forced convection, even if the background T is higher than at natural convection. Background IR radiation strongly affects the responses to T oscillations: the discharge rates of both warm cells are higher the higher the power of the IR background. We compared the warm cell responses with the T measured inside small model objects shaped like a cylinder, a cone, or a disc. The experiments indicate that passive thermal effects of the sense organs rather than intrinsic properties of the sensory cells are responsible for the observed results. PMID:25609113

History of infrared detectors

NASA Astrophysics Data System (ADS)

Rogalski, A.

2012-09-01

This paper overviews the history of infrared detector materials starting with Herschel's experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940's. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ˜3 μm. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called "dual-use technology applications." One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

Liver fat contents, abdominal adiposity and insulin resistance in non-diabetic prevalent hemodialysis patients.

PubMed

Chen, Hung-Yuan; Lin, Chien-Chu; Chiu, Yen-Ling; Hsu, Shih-Ping; Pai, Mei-Fen; Yang, Ju-Yeh; Wu, Hon-Yen; Peng, Yu-Sen

2014-01-01

The liver fat contents and abdominal adiposity correlate well with insulin resistance (IR) in the general population. However, the relationship between liver fat content, abdominal adiposity and IR in non-diabetic hemodialysis (HD) patients remains unclear. This study aimed to clarify the associations among these factors. This is a cross-sectional, observational study. All patients received abdominal ultrasound for liver fat content. Abdominal adiposity was quantified with the conicity index (Ci) and waist circumference (WC). We checked the homeostasis model assessment for insulin resistance index (HOMA-IR) for IR. A total of 112 patients (60 women) were analyzed. Subjects with higher liver fat contents and WC had higher IR indices. But Ci did not correlate with IR indices. In both the multi-variable linear regression model and the logistic regression model, only higher liver fat content predicted a severe IR status. Liver fat contents have a remarkable correlation with IR; however, abdominal adiposity, measured either by Ci or WC, dose not independently correlate with IR in non-diabetic prevalent HD patients. © 2014 S. Karger AG, Basel.

Current studies and improvements on a single frequency blue source generated by second harmonic from IR

NASA Astrophysics Data System (ADS)

Khademian, Ali; Jampani, Sai Lakshman; Truscott, Matthew; Jayaraj, Anooja; Shiner, David

2017-04-01

We have reported 81.5% efficiency in generating 500 mW of blue at 486 nm by second harmonic generation (SHG) from the IR, using a periodically poled Lithium Tantalate (PPSLT) crystal. Initially a total cavity loss of 0.65% was observed. We developed techniques for careful measurement of individual losses such as scattering and absorption in the crystal and mirrors, polarization misalignment caused by the crystal and back reflection from the periodically poled boundaries of crystal. We have replaced the crystal with a tilted periodically poled crystal. This eliminated the reflection loss, but scattering in the crystal, we speculate from the MgO doping, is still causing enough feedback to destabilize the IR source. We are also replacing cavity mirrors with ultra-low loss sputtered mirrors to minimize their contribution to loss. Crystal lifetime at different blue power levels is being investigated. In our setup a mixed signal processer (MSP) is used for cavity locking and temperature stabilizing. Once MSP is programed by a computer interface, it can be installed inside the cavity housing, making the laser source standalone and self-sufficient. We have been able to stabilize and lock the laser cavity length, the temperature of the IR laser source, the temperature of fiber Bragg grating (FBG), and the temperature of the nonlinear crystal using the MSP, matching the performance of high end commercial temperature controllers and lock-in amplifiers. Our recent progress and improvements will be presented. This work is supported by NSF award 1404498.

Thermal monitoring of hydrothermal activity by permanent infrared automatic stations: Results obtained at Solfatara di Pozzuoli, Campi Flegrei (Italy)

NASA Astrophysics Data System (ADS)

Chiodini, G.; Vilardo, G.; Augusti, V.; Granieri, D.; Caliro, S.; Minopoli, C.; Terranova, C.

2007-12-01

A permanent automatic infrared (IR) station was installed at Solfatara crater, the most active zone of Campi Flegrei caldera. After a positive in situ calibration of the IR camera, we analyze 2175 thermal IR images of the same scene from 2004 to 2007. The scene includes a portion of the steam heated hot soils of Solfatara. The experiment was initiated to detect and quantify temperature changes of the shallow thermal structure of a quiescent volcano such as Solfatara over long periods. Ambient temperature is the main parameter affecting IR temperatures, while air humidity and rain control image quality. A geometric correction of the images was necessary to remove the effects of slow movement of the camera. After a suitable correction the images give a reliable and detailed picture of the temperature changes, over the period October 2004 to January 2007, which suggests that origin of the changes were linked to anthropogenic activity, vegetation growth, and the increase of the flux of hydrothermal fluids in the area of the hottest fumaroles. Two positive temperature anomalies were registered after the occurrence of two seismic swarms which affected the hydrothermal system of Solfatara in October 2005 and October 2006. It is worth noting that these signs were detected in a system characterized by a low level of activity with respect to systems affected by real volcanic crisis where more spectacular results will be expected. Results of the experiment show that this kind of monitoring system can be a suitable tool for volcanic surveillance.

Comparison of Two Fluid Replacement Protocols During a 20-km Trail Running Race in the Heat.

PubMed

Lopez, Rebecca M; Casa, Douglas J; Jensen, Katherine A; Stearns, Rebecca L; DeMartini, Julie K; Pagnotta, Kelly D; Roti, Melissa W; Armstrong, Lawrence E; Maresh, Carl M

2016-09-01

Lopez, RM, Casa, DJ, Jensen, K, Stearns, RL, DeMartini, JK, Pagnotta, KD, Roti, MW, Armstrong, LE, and Maresh, CM. Comparison of two fluid replacement protocols during a 20-km trail running race in the heat. J Strength Cond Res 30(9): 2609-2616, 2016-Proper hydration is imperative for athletes striving for peak performance and safety, however, the effectiveness of various fluid replacement strategies in the field setting is unknown. The purpose of this study was to investigate how two hydration protocols affect physiological responses and performance during a 20-km trail running race. A randomized, counter-balanced, crossover design was used in a field setting (mean ± SD: WBGT 28.3 ± 1.9° C). Well-trained male (n = 8) and female (n = 5) runners (39 ± 14 years; 175 ± 9 cm; 67.5 ± 11.1 kg; 13.4 ± 4.6% BF) completed two 20-km trail races (5 × 4-km loop) with different water hydration protocols: (a) ad libitum (AL) consumption and (b) individualized rehydration (IR). Data were analyzed using repeated measures ANOVA. Paired t-tests compared pre-race-post-race measures. Main outcome variables were race time, heart rate (HR), gastrointestinal temperature (TGI), fluid consumed, percent body mass loss (BML), and urine osmolality (Uosm). Race times between groups were similar. There was a significant condition × time interaction (p = 0.048) for HR, but TGI was similar between conditions. Subjects replaced 30 ± 14% of their water losses in AL and 64 ± 16% of their losses in IR (p < 0.001). Ad libitum trial experienced greater BML (-2.6 ± 0.5%) compared with IR (-1.3 ± 0.5%; p < 0.001). Pre-race to post-race Uosm differences existed between AL (-273 ± 146 mOsm) and IR (-145 ± 215 mOsm, p = 0.032). In IR, runners drank twice as much fluid than AL during the 20-km race, leading to > 2% BML in AL. Ad libitum drinking resulted in 1.3% greater BML over the 20-km race, which resulted in no thermoregulatory or performance differences from IR.

[Monitoring the thermal plume from coastal nuclear power plant using satellite remote sensing data: modeling, and validation].

PubMed

Zhu, Li; Zhao, Li-Min; Wang, Qiao; Zhang, Ai-Ling; Wu, Chuan-Qing; Li, Jia-Guo; Shi, Ji-Xiang

2014-11-01

Thermal plume from coastal nuclear power plant is a small-scale human activity, mornitoring of which requires high-frequency and high-spatial remote sensing data. The infrared scanner (IRS), on board of HJ-1B, has an infrared channel IRS4 with 300 m and 4-days as its spatial and temporal resolution. Remote sensing data aquired using IRS4 is an available source for mornitoring thermal plume. Retrieval pattern for coastal sea surface temperature (SST) was built to monitor the thermal plume from nuclear power plant. The research area is located near Guangdong Daya Bay Nuclear Power Station (GNPS), where synchronized validations were also implemented. The National Centers for Environmental Prediction (NCEP) data was interpolated spatially and temporally. The interpolated data as well as surface weather conditions were subsequently employed into radiative transfer model for the atmospheric correction of IRS4 thermal image. A look-up-table (LUT) was built for the inversion between IRS4 channel radiance and radiometric temperature, and a fitted function was also built from the LUT data for the same purpose. The SST was finally retrieved based on those preprocessing procedures mentioned above. The bulk temperature (BT) of 84 samples distributed near GNPS was shipboard collected synchronically using salinity-temperature-deepness (CTD) instruments. The discrete sample data was surface interpolated and compared with the satellite retrieved SST. Results show that the average BT over the study area is 0.47 degrees C higher than the retrieved skin temperature (ST). For areas far away from outfall, the ST is higher than BT, with differences less than 1.0 degrees C. The main driving force for temperature variations in these regions is solar radiation. For areas near outfall, on the contrary, the retrieved ST is lower than BT, and greater differences between the two (meaning > 1.0 degrees C) happen when it gets closer to the outfall. Unlike the former case, the convective heat transfer resulting from the thermal plume is the primary reason leading to the temperature variations. Temperature rising (TR) distributions obtained from remote sensing data and in-situ measurements are consistent, except that the interpolated BT shows more level details (> 5 levels) than that of the ST (up to 4 levels). The areas with higher TR levels (> 2) are larger on BT maps, while for lower TR levels (≤ 2), the two methods perform with no obvious differences. Minimal errors for satellite-derived SST occur regularly around local time 10 a. m. This makes the remote sensing results to be substitutes for in-situ measurements. Therefore, for operational applications of HJ-1B IRS4, remote sensing technique can be a practical approach to monitoring the nuclear plant thermal pollution around this time period.

Size, weight, and power reduction of mercury cadmium telluride infrared detection modules

NASA Astrophysics Data System (ADS)

Breiter, Rainer; Ihle, Tobias; Wendler, Joachim C.; Lutz, Holger; Rutzinger, Stefan; Schallenberg, Timo; Hofmann, Karl C.; Ziegler, Johann

2011-06-01

Application requirements driving present IR technology development activities are improved capability to detect and identify a threat as well as the need to reduce size weight and power consumption (SWaP) of thermal sights. In addition to the development of 3rd Gen IR modules providing dual-band or dual-color capability, AIM is focused on IR FPAs with reduced pitch and high operating temperature for SWaP reduction. State-of-the-art MCT technology allows AIM the production of mid-wave infrared (MWIR) detectors operating at temperatures exceeding 120 K without any need to sacrifice the 5-μm cut-off wavelength. These FPAs allow manufacturing of low cost IR modules with minimum size, weight, and power for state-of-the-art high performance IR systems. AIM has realized full TV format MCT 640×512 mid-wave and long-wave IR detection modules with a 15-μm pitch to meet the requirements of critical military applications like thermal weapon sights or thermal imagers in unmanned aerial vehicles applications. In typical configurations like an F/4.6 cold shield for the 640×512 MWIR module an noise equivalent temperature difference (NETD) <25 mK @ 5 ms integration time is achieved, while the long-wavelength infrared (LWIR) modules achieve an NETD <38 mK @ F/2 and 180 μs integration time. For the LWIR modules, FPAs with a cut-off up to 10 μm have been realized. The modules are available either with different integral rotary cooler configurations for portable applications that require minimum cooling power or a new split linear cooler providing long lifetime with a mean time to failure (MTTF) > 20000, e.g., for warning sensors in 24/7 operation. The modules are available with optional image processing electronics providing nonuniformity correction and further image processing for a complete IR imaging solution. The latest results and performance of those modules and their applications are presented.

FIRE_AX_UW_DSCRT

Atmospheric Science Data Center

2015-11-25

... Analyzer IR CO2 Analyzer Optical Counter Platinum Resistance Spectrometer Spatial Coverage:  (32.34, ... Diameter Particle Number Concentration Potential Temperature Sulfate Sulfur Dioxide Temperature Order Data:  ...

Nighttime Infrared radiative cooling and opacity inferred by REMS Ground Temperature Sensor Measurements

NASA Astrophysics Data System (ADS)

Martín-Torres, Javier; Paz Zorzano, María; Pla-García, Jorge; Rafkin, Scot; Lepinette, Alain; Sebastián, Eduardo; Gómez-Elvira, Javier; REMS Team

2013-04-01

Due to the low density of the Martian atmosphere, the temperature of the surface is controlled primarily by solar heating, and infrared cooling to the atmosphere and space, rather than heat exchange with the atmosphere. In the absence of solar radiation the infrared (IR) cooling, and then the nighttime surface temperatures, are directly controlled by soil termal inertia and atmospheric optical thickness (τ) at infrared wavelengths. Under non-wind conditions, and assuming no processes involving latent heat changes in the surface, for a particular site where the rover stands the main parameter controlling the IR cooling will be τ. The minimal ground temperature values at a fixed position may thus be used to detect local variations in the total dust/aerosols/cloud tickness. The Ground Temperature Sensor (GTS) and Air Temperature Sensor (ATS) in the Rover Environmental Monitoring Station (REMS) on board the Mars Science Laboratory (MSL) Curiosity rover provides hourly ground and air temperature measurements respectively. During the first 100 sols of operation of the rover, within the area of low thermal inertia, the minimal nightime ground temperatures reached values between 180 K and 190 K. For this season the expected frost point temperature is 200 K. Variations of up to 10 K have been observed associated with dust loading at Gale at the onset of the dust season. We will use these measurements together with line-by-line radiative transfer simulations using the Full Transfer By Optimized LINe-by-line (FUTBOLIN) code [Martín-Torres and Mlynczak, 2005] to estimate the IR atmospheric opacity and then dust/cloud coverage over the rover during the course of the MSL mission. Monitoring the dust loading and IR nightime cooling evolution during the dust season will allow for a better understanding of the influence of the atmosphere on the ground temperature and provide ground truth to models and orbiter measurements. References Martín-Torres, F. J. and M. G. Mlynczak, Application of FUTBOLIN (FUll Transfer By Ordinary Line-by-Line) to the analysis of the solar system and extrasolar planetary atmospheres, Bulletin of the American Astronomical Society, Vol. 37, p.1566, 2005

Results of a joint NOAA/NASA sounder simulation study

NASA Technical Reports Server (NTRS)

Phillips, N.; Susskind, Joel; Mcmillin, L.

1988-01-01

This paper presents the results of a joint NOAA and NASA sounder simulation study in which the accuracies of atmospheric temperature profiles and surface skin temperature measuremnents retrieved from two sounders were compared: (1) the currently used IR temperature sounder HIRS2 (High-resolution Infrared Radiation Sounder 2); and (2) the recently proposed high-spectral-resolution IR sounder AMTS (Advanced Moisture and Temperature Sounder). Simulations were conducted for both clear and partial cloud conditions. Data were analyzed at NASA using a physical inversion technique and at NOAA using a statistical technique. Results show significant improvement of AMTS compared to HIRS2 for both clear and cloudy conditions. The improvements are indicated by both methods of data analysis, but the physical retrievals outperform the statistical retrievals.

Noninvasive Thermal Ablation of Osteomyelitis-Causing Bacteria using Functionalized Nanoparticles

DTIC Science & Technology

2012-03-01

2008). One alternative approach to antibiotics includes the use of near infrared ( IR ) radiation to thermally kill pathogenic organisms (Kam, 2005...Zharov, 2006). Whereas near IR wavelengths pass harmlessly through the human body, they are known to heat gold nanoshells to high temperatures (>70°C...nanoparticles both alone and complexed with PlyCB (Fig. 8). Task 3. Determine depth of IR radiation penetration and range of thermal damage. (months 11- 15

GaN-based THz advanced quantum cascade lasers for manned and unmanned systems

NASA Astrophysics Data System (ADS)

Anwar, A. F. M.; Manzur, Tariq; Lefebvre, Kevin R.; Carapezza, Edward M.

2009-09-01

In recent years the use of Unmanned Autonomous Vehicles (UAV) has seen a wider range of applications. However, their applications are restricted due to (a) advanced integrated sensing and processing electronics and (b) limited energy storage or on-board energy generation to name a few. The availability of a wide variety of sensing elements, operating at room temperatures, provides a great degree of flexibility with an extended application domain. Though sensors responding to a variable spectrum of input excitations ranging from (a) chemical, (b) biological, (c) atmospheric, (d) magnetic and (e) visual/IR imaging have been implemented in UAVs, the use of THz as a technology has not been implemented due to the absence of systems operating at room temperature. The integration of multi-phenomenological onboard sensors on small and miniature unmanned air vehicles will dramatically impact the detection and processing of challenging targets, such as humans carrying weapons or wearing suicide bomb vests. Unmanned air vehicles have the potential of flying over crowds of people and quickly discriminating non-threat humans from treat humans. The state of the art in small and miniature UAV's has progressed to vehicles of less than 1 pound in weight but with payloads of only a fraction of a pound. Uncooled IR sensors, such as amorphous silicon and vanadium oxide microbolometers with MRT's of less than 70mK and requiring power of less than 250mW, are available for integration into small UAV's. These sensors are responsive only up to approximately 14 microns and do not favorably compare with THz imaging systems for remotely detecting and classifying concealed weapons and bombs. In the following we propose the use of THz GaN-based QCL operating at room temperature as a possible alternative.

Yb-fiber-pumped mid-infrared picosecond optical parametric oscillator tunable across 6.2-6.7 µm

NASA Astrophysics Data System (ADS)

Kumar, S. Chaitanya; Casals, J. Canals; Parsa, S.; Zawilski, K. T.; Schunemann, P. G.; Ebrahim-Zadeh, M.

2018-06-01

We report a high-average-power picosecond optical parametric oscillator (OPO) tunable in the mid-infrared (mid-IR) based on CdSiP2 synchronously pumped by an Yb-fiber laser at 80 MHz repetition rate. Successful operation of this high-repetition-rate singly-resonant picosecond OPO has been enabled by the improved CSP crystal quality over a long interaction length. The OPO can be tuned across 1264-1284 nm in the near-IR signal and 6205-6724 nm in the mid-IR idler by temperature tuning the CSP crystal over 39-134 °C. By deploying a 5% output coupler for the resonant signal, we have extracted up to 44 mW of average power in the near-IR and up to 95 mW of non-resonant idler power at 6205 nm at 6.3% total conversion efficiency, with > 50 mW over > 55% of the mid-IR tuning range. We have investigated temperature-tuning characteristics of the OPO and compared the data with the theoretical calculations using the recent Sellmeier and thermo-optic coefficients for CdSiP2. The signal pulses from the OPO exhibit a Gaussian pulse duration of 19 ps centered at 1284 nm. We have also studied the output power stability of the OPO, resulting in a passive stability better than 1.9% rms for the near-IR signal and 2.4% rms for the mid-IR idler, measured over > 17 h, with both beams in high spatial quality.

IR radiation characteristics and operating range research for a quad-rotor unmanned aircraft vehicle.

PubMed

Gong, Mali; Guo, Rui; He, Sifeng; Wang, Wei

2016-11-01

The security threats caused by multi-rotor unmanned aircraft vehicles (UAVs) are serious, especially in public places. To detect and control multi-rotor UAVs, knowledge of IR characteristics is necessary. The IR characteristics of a typical commercial quad-rotor UAV are investigated in this paper through thermal imaging with an IR camera. Combining the 3D geometry and IR images of the UAV, a 3D IR characteristics model is established so that the radiant power from different views can be obtained. An estimation of operating range to detect the UAV is calculated theoretically using signal-to-noise ratio as the criterion. Field experiments are implemented with an uncooled IR camera in an environment temperature of 12°C and a uniform background. For the front view, the operating range is about 150 m, which is close to the simulation result of 170 m.

Future development of IR thermovision weather satellite equipment

NASA Technical Reports Server (NTRS)

Listratov, A. V.

1974-01-01

The self radiation of the surface being viewed is used for image synthesis in IR thermovision equipment. The installation of such equipment aboard weather satellites makes it possible to obtain cloud cover pictures of the earth's surface in a complete orbit, regardless of the illumination conditions, and also provides quantitative information on the underlying surface temperature and cloud top height. Such equipment is used successfully aboard the Soviet satellites of the Meteor system, and experimentally on the American satellites of the Nimbus series. With regard to surface resolution, the present-day IR weather satellite equipment is inferior to the television equipment. This is due primarily to the comparatively low detectivity of the IR detectors used. While IR equipment has several fundamental advantages in comparison with the conventional television equipment, the problem arises of determining the possibility for future development of weather satellite IR thermovision equipment. Criteria are examined for evaluating the quality of IR.

Passive microwave structure of severe tornadic storms on 16 November 1987

NASA Technical Reports Server (NTRS)

Heymsfield, Gerald M.; Fulton, Richard

1994-01-01

Passive microwave observations using the Special Sensor Microwave/Imager (SSM/I) are presented for severe tornadic storms in the lower midwestern United States on 16 November 1987. These measurements are compared with Geostationary Operational Environmental Satellite infrared (IR) measurements for the same case. The IR observations had a classic 'V' cold feature commonly associated with severe Midwest thunderstorms. The minimum microwave brightness temperatures at 86 GHz, which primarily respond to ice scattering by larger ice particles, were located in the convective region and the warm interior of the anvil top, between the arms of the IR V feature. The interior warm region was the only portion of the entire anvil region that had high 86-GHz polarization difference temperatures. Microphysical implications of these multispectral observations are discussed. The observations suggest that there are large variations of ice microphysical characteristics spatially and vertically in the anvil region. These observations are discussed in the context of previous dynamical and microphysical hypotheses on the IR V feature.

Comparison of the far-infrared and carbon monoxide emission in Heiles' Cloud 2 and B18

NASA Technical Reports Server (NTRS)

Snell, Ronald L.; Schloerb, F. Peter; Heyer, Mark H.

1989-01-01

A comparison is made of the far-IR emission detected by IRAS at 60 and 100 microns and the emission from C(-13)O in B18 and Heiles' Cloud 2. The results show that both these clouds have extended emission at the studied wavelengths and that this emission is correlated with the integrated intensity of (C-13)O emission. The dust temperature and optical depth, the gas column density, the mass of gas and dust, and the far-IR luminosity are derived and presented. The analysis shows that the dust optical depth is much better correlated with the gas column density than with the far-IR intensity. The dust temperature is found to be anticorrelated with the gas column density, suggesting that these clouds are externally heated by the interstellar radiation field. The far-IR luminosity-to-mass ratios for the clouds are substantially less than the average for the inner Galaxy.

Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates

PubMed Central

Behm, R Jürgen

2014-01-01

Summary As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C) and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm−1 characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl), are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed. PMID:24991512

Heat source reconstruction from noisy temperature fields using a gradient anisotropic diffusion filter

NASA Astrophysics Data System (ADS)

Beitone, C.; Balandraud, X.; Delpueyo, D.; Grédiac, M.

2017-01-01

This paper presents a post-processing technique for noisy temperature maps based on a gradient anisotropic diffusion (GAD) filter in the context of heat source reconstruction. The aim is to reconstruct heat source maps from temperature maps measured using infrared (IR) thermography. Synthetic temperature fields corrupted by added noise are first considered. The GAD filter, which relies on a diffusion process, is optimized to retrieve as well as possible a heat source concentration in a two-dimensional plate. The influence of the dimensions and the intensity of the heat source concentration are discussed. The results obtained are also compared with two other types of filters: averaging filter and Gaussian derivative filter. The second part of this study presents an application for experimental temperature maps measured with an IR camera. The results demonstrate the relevancy of the GAD filter in extracting heat sources from noisy temperature fields.

Physical Retrieval of Surface Emissivity Spectrum from Hyperspectral Infrared Radiances

NASA Technical Reports Server (NTRS)

Li, Jun; Weisz, Elisabeth; Zhou, Daniel K.

2007-01-01

Retrieval of temperature, moisture profiles and surface skin temperature from hyperspectral infrared (IR) radiances requires spectral information about the surface emissivity. Using constant or inaccurate surface emissivities typically results in large retrieval errors, particularly over semi-arid or arid areas where the variation in emissivity spectrum is large both spectrally and spatially. In this study, a physically based algorithm has been developed to retrieve a hyperspectral IR emissivity spectrum simultaneously with the temperature and moisture profiles, as well as the surface skin temperature. To make the solution stable and efficient, the hyperspectral emissivity spectrum is represented by eigenvectors, derived from the laboratory measured hyperspectral emissivity database, in the retrieval process. Experience with AIRS (Atmospheric InfraRed Sounder) radiances shows that a simultaneous retrieval of the emissivity spectrum and the sounding improves the surface skin temperature as well as temperature and moisture profiles, particularly in the near surface layer.

Satellite and airborne IR sensor validation by an airborne interferometer

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

Gumley, L.E.; Delst, P.F. van; Moeller, C.C.

1996-11-01

The validation of in-orbit longwave IR radiances from the GOES-8 Sounder and inflight longwave IR radiances from the MODIS Airborne Simulator (MAS) is described. The reference used is the airborne University of Wisconsin High Resolution Interferometer Sounder (HIS). The calibration of each sensor is described. Data collected during the Ocean Temperature Interferometric Survey (OTIS) experiment in January 1995 is used in the comparison between sensors. Detailed forward calculations of at-sensor radiance are used to account for the difference in GOES-8 and HIS altitude and viewing geometry. MAS radiances and spectrally averaged HIS radiances are compared directly. Differences between GOES-8 andmore » HIS brightness temperatures, and GOES-8 and MAS brightness temperatures, are found to be with 1.0 K for the majority of longwave channels examined. The same validation approach will be used for future sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS). 11 refs., 2 figs., 4 tabs.« less

Polarization characteristics of a low catalyst loading PEM water electrolyzer operating at elevated temperature

NASA Astrophysics Data System (ADS)

Lee, Byung-Seok; Park, Hee-Young; Choi, Insoo; Cho, Min Kyung; Kim, Hyoung-Juhn; Yoo, Sung Jong; Henkensmeier, Dirk; Kim, Jin Young; Nam, Suk Woo; Park, Sehkyu; Lee, Kwan-Young; Jang, Jong Hyun

2016-03-01

The effect of temperature and pressure, and diffusion layer thickness is assessed on performance of a proton exchange membrane water electrolyzers (PEMWEs) with an ultralow iridium oxide (IrO2) loading (0.1 mg cm-2) anode prepared by electrodeposition and a Pt/C catalyzed cathode with a Pt loading of 0.4 mg cm-2. Increasing pressure to 2.5 bar at 120 °C enhances the water electrolysis current, so the anode electrodeposited with 0.1 mg cm-2 IrO2 gives a current density of 1.79 A cm-2 at 1.6 V, which is comparable to the conventional powder-type IrO2 electrode with 2.0 mg cm-2 at a temperature of 120 °C and pressure of 2.5 bar. The major factors for cell performances are rationalized in terms of overpotentials, water flow rates and thickness of diffusion layers, based on polarization behavior and ac-impedance response.

Local Effects of Ice Floes on Skin Sea Surface Temperature in the Marginal Ice Zone from UAVs

NASA Astrophysics Data System (ADS)

Zappa, C. J.; Brown, S.; Emery, W. J.; Adler, J.; Wick, G. A.; Steele, M.; Palo, S. E.; Walker, G.; Maslanik, J. A.

2013-12-01

Recent years have seen extreme changes in the Arctic. Particularly striking are changes within the Pacific sector of the Arctic Ocean, and especially in the seas north of the Alaskan coast. These areas have experienced record warming, reduced sea ice extent, and loss of ice in areas that had been ice-covered throughout human memory. Even the oldest and thickest ice types have failed to survive through the summer melt period in areas such as the Beaufort Sea and Canada Basin, and fundamental changes in ocean conditions such as earlier phytoplankton blooms may be underway. Marginal ice zones (MIZ), or areas where the "ice-albedo feedback" driven by solar warming is highest and ice melt is extensive, may provide insights into the extent of these changes. Airborne remote sensing, in particular InfraRed (IR), offers a unique opportunity to observe physical processes at sea-ice margins. It permits monitoring the ice extent and coverage, as well as the ice and ocean temperature variability. It can also be used for derivation of surface flow field allowing investigation of turbulence and mixing at the ice-ocean interface. Here, we present measurements of visible and IR imagery of melting ice floes in the marginal ice zone north of Oliktok Point AK in the Beaufort Sea made during the Marginal Ice Zone Ocean and Ice Observations and Processes EXperiment (MIZOPEX) in July-August 2013. The visible and IR imagery were taken from the unmanned airborne vehicle (UAV) ScanEagle. The visible imagery clearly defines the scale of the ice floes. The IR imagery show distinct cooling of the skin sea surface temperature (SST) as well as a intricate circulation and mixing pattern that depends on the surface current, wind speed, and near-surface vertical temperature/salinity structure. Individual ice floes develop turbulent wakes as they drift and cause transient mixing of an influx of colder surface (fresh) melt water. The upstream side of the ice floe shows the coldest skin SST, and downstream the skin SST is mixed within the turbulent wake over 10s of meters. We compare the structure of circulation and mixing of the influx of cold skin SST driven by surface currents and wind. In-situ temperature measurements provide the context for the vertical structure of the mixing and its impact on the skin SST. Furthermore, comparisons to satellite-derived sea surface temperature of the region are presented. The accuracy of satellite derived SST products and how well the observed skin SSTs represent ocean bulk temperatures in polar regions is not well understood, due in part to lack of observations. Estimated error in the polar seas is relatively high at up to 0.4 deg. C compared to less than 0.2 deg. C for other areas. The goal of these and future analyses of the MIZOPEX data set is to elucidate a basic question that is significant for the entire Earth system. Have these regions passed a tipping point, such that they are now essentially acting as sub-Arctic seas where ice disappears in summer, or instead whether the changes are transient, with the potential for the ice pack to recover?

Infrared spectroscopic study of thermotropic phase behavior of newly developed synthetic biopolymers

NASA Astrophysics Data System (ADS)

Bista, Rajan K.; Bruch, Reinhard F.; Covington, Aaron M.

2011-10-01

The thermotropic phase behavior of a suite of newly developed self-forming synthetic biopolymers has been investigated by variable-temperature Fourier transform infrared (FT-IR) absorption spectroscopy. The temperature-induced infrared spectra of these artificial biopolymers (lipids) composed of 1,2-dimyristoyl- rac-glycerol-3-dodecaethylene glycol (GDM-12), 1,2-dioleoyl- rac-glycerol-3-dodecaethylene glycol (GDO-12) and 1,2-distearoyl- rac-glycerol-3-triicosaethylene glycol (GDS-23) in the spectral range of 4000-500 cm -1 have been acquired by using a thin layered FT-IR spectrometer in conjunction with a custom built temperature-controlled demountable liquid cell having a pathlength of ˜15 μm. The lipids under consideration have long hydrophobic acyl chains and contain various units of hydrophilic polyethylene glycol (PEG) headgroups. In contrast to conventional phospholipids, this new kind of lipids forms liposomes or nanovesicles spontaneously upon hydration, without requiring external activation energy. We have found that the thermal stability of the PEGylated lipids differs greatly depending upon the acyl chain-lengths as well as the nature of the associated bonds and the number of PEG headgroup units. In particular, GDM-12 (saturated 14 hydrocarbon chains with 12 units of PEG headgroup) exhibits one sharp order-disorder phase transition over a temperature range increasing from 3 °C to 5 °C. Similarly, GDS-23 (saturated 18 hydrocarbon chains with 23 units of PEG headgroup) displays comparatively broad order-disorder phase transition profiles between temperature 17 °C and 22 °C. In contrast, GDO-12 (monounsaturated 18 hydrocarbon chains with 12 units of PEG headgroup) does not reveal any order-disorder transition phenomena demonstrating a highly disordered behavior for the entire temperature range. To confirm these observations, differential scanning calorimetry (DSC) was applied to the samples and revealed good agreement with the infrared spectroscopy results. Finally, the investigation of thermal properties of lipids is extremely critical for numerous purposes and the result obtained in this work may find application in various studies including the development of PEGylated lipid based novel drug and substances delivery vehicles.

Temperature dependence of the triplet diffusion and quenching rates in films of an Ir(ppy)3 -cored dendrimer

NASA Astrophysics Data System (ADS)

Ribierre, J. C.; Ruseckas, A.; Samuel, I. D. W.; Staton, S. V.; Burn, P. L.

2008-02-01

We study photoluminescence and triplet-triplet exciton annihilation in a neat film of a fac-tris(2-phenylpyridyl)iridium(III) [Ir(ppy)3] -cored dendrimer and in its blend with a 4,4' -bis( N -carbazolyl)biphenyl host for the temperature range of 77-300K . The nearest neighbor hopping rate of triplet excitons is found to increase by a factor of 2 with temperature between 150 and 300K and is temperature independent at lower temperature. The intermolecular quenching rate follows the Arrhenius law with an activation energy of 7meV , which can be explained by stronger dipole-dipole interactions with the donor molecule in the higher triplet substate. The results indicate that energy disorder has no significant effect on triplet transport and quenching in these materials.

Comparing Geophysical Methods for Determining the Thickness of Arctic Sea Ice: Is There a Correlation Between Thickness and Surface Temperature?

NASA Astrophysics Data System (ADS)

Robertson, R.; Bowman, T.; Eagle, J. L.; Fisher, L.; Mankowski, K.; McGrady, N.; Schrecongost, N.; Voll, H.; Zulfiqar, A.; Herman, R. B.

2016-12-01

Several small geophysical surveys were conducted on the Chukchi Sea ice just offshore from the Naval Arctic Research Laboratory near Barrow, Alaska, in March, 2016. The goal was to investigate a possible correlation between the surface temperature and the thickness of the sea ice, as well as to test a potential new method for more accurately determining ice thickness. Surveys were conducted using a capacitively coupled resistivity array, a custom built thermal sensor array sled, ground penetrating radar (GPR), and an ice drill. The thermal sensor array was based on an Arduino microcontroller. It used an infrared (IR) sensor to determine surface temperature, and thermistor-based sensors to determine vertical air temperatures at 6 evenly spaced heights up to a maximum of 1.5 meters. Surface temperature (IR) data show possible correlations with ice drill, resistivity, and GPR data. The vertical air sensors showed almost no variation for any survey line which we postulate is due to the constant wind during each survey. Ice drill data show ice thickness along one 200 meter line varied from 79-95 cm, with an average of 87 cm. The thickness appears to be inversely correlated to surface temperatures. Resistivity and IR data both showed abrupt changes when crossing from the shore to the sea ice along a 400 meter line. GPR and IR data showed similar changes along a separate 900 meter line, suggesting that surface temperature and subsurface composition are related. Resistivity data were obtained in two locations by using the array in an expanding dipole-dipole configuration with 2.5 meter dipoles. The depth to the ice/water boundary was calculated using a "cumulative resistivity" plot and matched the depths obtained via the ice drill to within 2%. This has initiated work to develop a microcontroller-based resistivity array specialized for thickness measurements of thin ice.

Qualitative study of sexual functioning in couples with erectile dysfunction: prospective evaluation of the thermography diagnostic system.

PubMed

Ng, Wan Kee; Ng, Yin Kwee; Tan, Yung Khan

2009-01-01

To evaluate the prospective use of the thermography diagnostic system in assessing sexual function in patients with erectile dysfunction (ED). Thermographs were taken on 14 subjects in a clinical trial conducted at Tan Tock Seng Hospital. After a thorough clinical interview with a standardized questionnaire, patients were scanned for baseline temperature profile before being given an oral dose of sildenafil 100 mg. Subjects were scanned again in the same setting an hour later. If so desired, subjects were given visual stimulation and were allowed minimum direct stimulation, excluding the penis, to elicit erection. Temperature profiles were analyzed using the thermography analysis software in the VarioCAM camera. Three representative cases are presented to illustrate the potential for using the Infrared thermography (IR) diagnostic system in differentiating psychogenic ED. IR was able to capture a significant difference in blood flow to the corpus cavernosum. Subjects with psychogenic ED have higher surface temperatures (34.3 degrees C +/- 0.71 in the flaccid state and 35.3 degrees C +/- 0.2 during erection) compared to subjects with organic ED (33.64 degrees C +/- 0.4 in flaccid and 33.55 degrees C +/- 0.91 during erection). The difference in surface temperature between flaccid and erected states in subjects with organic ED was not significant. The proposed diagnostic test based on IR has tremendous clinical potential in differentiating psychogenic ED from organic ED. IR could potentially be a portable, noninvasive and convenient adjunct in the diagnosis and management of ED.

Welding of unique and advanced alloys for space and high-temperature applications: welding and weldability of iridium and platinum alloys

DOE PAGES

David, Stan A.; Miller, Roger G.; Feng, Zhili

2016-08-31

Advances have been made in developing alloys for space power systems for spacecraft that travel long distances to various planets. The spacecraft are powered by radioisotope thermoelectric generators (RTGs) and the fuel element in RTGs is plutonia. For safety and containment of the radioactive fuel element, the heat source is encapsulated in iridium or platinum alloys. Ir and Pt alloys are the alloys of choice for encapsulating radioisotope fuel pellets. Ir and Pt alloys were chosen because of their high-temperature properties and compatibility with the oxide fuel element and the graphite impact shells. This review addresses the alloy design andmore » welding and weldability of Ir and Pt alloys for use in RTGs.« less

Welding of unique and advanced alloys for space and high-temperature applications: welding and weldability of iridium and platinum alloys

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

David, Stan A.; Miller, Roger G.; Feng, Zhili

Advances have been made in developing alloys for space power systems for spacecraft that travel long distances to various planets. The spacecraft are powered by radioisotope thermoelectric generators (RTGs) and the fuel element in RTGs is plutonia. For safety and containment of the radioactive fuel element, the heat source is encapsulated in iridium or platinum alloys. Ir and Pt alloys are the alloys of choice for encapsulating radioisotope fuel pellets. Ir and Pt alloys were chosen because of their high-temperature properties and compatibility with the oxide fuel element and the graphite impact shells. This review addresses the alloy design andmore » welding and weldability of Ir and Pt alloys for use in RTGs.« less

Manipulations of core temperatures in ischemia-reperfusion lung injury in rabbits.

PubMed

Chang, Hung; Huang, Kun-Lun; Li, Min-Hui; Hsu, Ching-Wang; Tsai, Shih-Hung; Chu, Shi-Jye

2008-01-01

The present study was designed to determine the effect of various core temperatures on acute lung injury induced by ischemia-reperfusion (I/R) in our isolated rabbit lung model. Typical acute lung injury was successfully induced by 30 min of ischemia followed by 90 min of reperfusion observation. The I/R elicited a significant increase in pulmonary arterial pressure, microvascular permeability (measured by using the capillary filtration coefficient, Kfc), Delta Kfc ratio, lung weight gain and the protein concentration of the bronchoalveolar lavage fluid. Mild hypothermia significantly attenuated acute lung injury induced by I/R, all parameters having decreased significantly (p<0.05); conversely, mild hyperthermia did not further exacerbate acute lung injury. These experimental data suggest that mild hypothermia significantly ameliorated acute lung injury induced by ischemia-reperfusion in rabbits.

An infrared based sensor system for the detection of ethylene for the discrimination of fruit ripening

NASA Astrophysics Data System (ADS)

Kathirvelan, J.; Vijayaraghavan, R.

2017-09-01

We report the fabrication and testing of a prototype ethylene sensing device for use in fruit ripening applications. A sensor based on infrared (IR) thermal emission was developed and used to detect the ethylene level released during the fruit ripening process. An IR thermal source tuned to the 10.6 μm wavelength was linked to a high-sensitivity silicon temperature detector. When introduced into the wave path between the IR source and temperature detector, ethylene absorbs the 10.6 μm IR waves and decreases the surface temperature of the detector. The output is then converted to an electrical signal (in mV), which gives a direct measurement of the ethylene level. Using this sensor, ethylene concentration measured from a fruit sample continuously decreased from 59 to 5 ppm during the natural ripening process. The sensor exhibited a sensitivity of 3.3 ± 0.2% (change in detector output (mV)/ppm × 100) and could measure concentrations as low as 5 ppm with rise and recovery times of 1 and 3 s, respectively. The system demonstrated good reproducibility. Devices employing this sensor system may be used for fruit ripening applications on site and in the field and for screening artificially ripened fruits, therefore contributing to ensure food safety.

High temperature stress and spikelet fertility in rice (Oryza sativa L.).

PubMed

Jagadish, S V K; Craufurd, P Q; Wheeler, T R

2007-01-01

In future climates, greater heat tolerance at anthesis will be required in rice. The effect of high temperature at anthesis on spikelet fertility was studied on IR64 (lowland indica) and Azucena (upland japonica) at 29.6 degrees C (control), 33.7 degrees C, and 36.2 degrees C tissue temperatures. The objectives of the study were to: (i) determine the effect of temperature on flowering pattern; (ii) examine the effect of time of day of spikelet anthesis relative to a high temperature episode on spikelet fertility; and (iii) study the interactions between duration of exposure and temperature on spikelet fertility. Plants were grown at 30/24 degrees C day/night temperature in a greenhouse and transferred to growth cabinets for the temperature treatments. Individual spikelets were marked with paint to relate fertility to the time of exposure to different temperatures and durations. In both genotypes the pattern of flowering was similar, and peak anthesis occurred between 10.30 h and 11.30 h at 29.2 degrees C, and about 45 min earlier at 36.2 degrees C. In IR64, high temperature increased the number of spikelets reaching anthesis, whereas in Azucena numbers were reduced. In both genotypesor=33.7 degrees C at anthesis caused sterility. In IR64, there was no interaction between temperature and duration of exposure, and spikelet fertility was reduced by about 7% per degrees C>29.6 degrees C. In Azucena there was a significant interaction and spikelet fertility was reduced by 2.4% degrees Cd-1 above a threshold of 33 degrees C. Marking individual spikelets is an effective method to phenotype genotypes and lines for heat tolerance that removes any apparent tolerance due to temporal escape.

Research on simulated infrared image utility evaluation using deep representation

NASA Astrophysics Data System (ADS)

Zhang, Ruiheng; Mu, Chengpo; Yang, Yu; Xu, Lixin

2018-01-01

Infrared (IR) image simulation is an important data source for various target recognition systems. However, whether simulated IR images could be used as training data for classifiers depends on the features of fidelity and authenticity of simulated IR images. For evaluation of IR image features, a deep-representation-based algorithm is proposed. Being different from conventional methods, which usually adopt a priori knowledge or manually designed feature, the proposed method can extract essential features and quantitatively evaluate the utility of simulated IR images. First, for data preparation, we employ our IR image simulation system to generate large amounts of IR images. Then, we present the evaluation model of simulated IR image, for which an end-to-end IR feature extraction and target detection model based on deep convolutional neural network is designed. At last, the experiments illustrate that our proposed method outperforms other verification algorithms in evaluating simulated IR images. Cross-validation, variable proportion mixed data validation, and simulation process contrast experiments are carried out to evaluate the utility and objectivity of the images generated by our simulation system. The optimum mixing ratio between simulated and real data is 0.2≤γ≤0.3, which is an effective data augmentation method for real IR images.

Effect of Zn-site substitution with Ga on non-Fermi liquid behavior in PrIr2Zn20

NASA Astrophysics Data System (ADS)

Yamada, R. J.; Onimaru, T.; Uenishi, K.; Yamane, Y.; Wakiya, K.; Matsumoto, K. T.; Umeo, K.; Takabatake, T.

2018-05-01

PrIr2Zn20 exhibits an antiferroquadrupolar (AFQ) order at TQ = 0.11 K, above which temperature the electrical resistivity ρ(T) shows an upward curvature and the magnetic specific heat divided by temperature Cm/T follows - lnT dependence. The non-Fermi Liquid (NFL) behaviors have suggested formation of a quadrupole Kondo lattice. In the present work, we have studied the effect of Ga substitution for Zn on the NFL behavior by the measurements of the specific heat C, the magnetic susceptibility χ, and ρ of PrIr2Zn20-xGax (0 ≤ x ≤ 0.25). With increasing x, the characteristic temperature T0 defined as the temperature where the magnetic entropy Sm reaches (3/4)Rln2 is increased by a factor of 3.5. Similarly, another characteristic temperature TR below which ρ(T) starts decreasing with the upward curvature increases with x by a factor of 1.2. The increments of both T0 and TR may be attributed to the possible split of the Γ3 doublet by symmetry lowering of the Pr sites. Otherwise, the quadrupole Kondo lattice would be stabilized by the enhanced c-f hybridization due to the increment of the 4p electronic density and/or the chemical pressure effect.

Small-scale structure of the CO emission in S255 from lunar occultation observations

NASA Technical Reports Server (NTRS)

Schloerb, F. P.; Scoville, N. Z.

1980-01-01

Two lunar occultations of the S255 H II region/molecular cloud complex were observed in the 2.6 mm CO line during 1978 and 1979. The resolution obtained (between 4 arcsec and 7 arcsec) enables us to resolve bright sources that are much smaller than the 44 arcsec telescope beam. In addition to the large-scale structure (approximately 10 arcmin in size) seen in previous CO maps, the observations reveal two high-temperature emission regions in the cloud core associated with two compact infrared sources about 20 arcsec apart. The first CO hot spot is larger in size with a Gaussian width of 41 arcsec + or - 7 arcsec and a peak temperature of 65 K. Its center falls between the two small infrared sources S255 IRS1 and IRS2. The linear size and peak temperature of this source are remarkably similar to those in the Orion Kleinmann-Low nebula. The second source is revealed from a discontinuous change in the CO line flux as the lunar limb crossed S255 IRS1. The size of this component is less than 7 arcsec; its temperature must exceed 200 K. No evidence is found for exceptionally high temperatures at the boundary of the two H II regions crossed during the occultations.

Experimental Characterization of Soot Formation in Diffusion Flames and Explosive Fireballs

DTIC Science & Technology

2012-04-01

49 Figure 48. A side view of the elevated pressure-opposed flow rig on the test stand. The IR cutoff filter is shown in front of the...turbulent flows of mixed gasses in excited states. To perform this measurement, we have built and characterized a sensitive, selective infrared ( IR ...tool for TDLAS (Kosterev and Tittel, 2002). The QCL operates near room temperature and provides a powerful (~10 mW), stable, single-mode, mid- IR

Growth and characterization of Hg(1-x)Zn(x)Se

NASA Technical Reports Server (NTRS)

Andrews, R. N.

1986-01-01

Hg sub 1-xZn sub xSe alloys of composition x=0.10 were grown in a Bridgman-Stockbarger growth furnace at translation rates of 0.3 and 0.1 micron sec. The axial and radial composition profiles were determined using precision density measurements and IR transmission-edge-mapping, respectively. A more radially homogeneous alloy was produced at the slower growth rate, while the faster growth rate produced more axially homogeneous alloys. A determination of the electrical properties of the Hg sub 1-xZn sub xSe samples in the temperature range 300K-20K was also made. Typical carrier concentrations were on the order of magnitude of 10 to the 18th power cu/cm, and remained fairly constant as a function of temperature. A study was also made of the temperature dependence of the resistivity and Hall mobility. The effect of annealing in a selenium vapor on both the IR transmission and the electrical properties was determined. Annealing was effective in reducing the number of native donor defects and at the resulting lower carrier concentrations, charge carrier concentration was shown to be a function of temperature. Annealing caused the mobility to increase, primarily at the lower temperature, and the room temperature resistivity to increase. Annealing was also observed to greatly enhance the % IR transmittance of the samples. This was due primarily to the effect of annealing on decreasing the charge carrier concentration.

Partially oxidized iridium clusters within dendrimers: size-controlled synthesis and selective hydrogenation of 2-nitrobenzaldehyde

NASA Astrophysics Data System (ADS)

Higaki, Tatsuya; Kitazawa, Hirokazu; Yamazoe, Seiji; Tsukuda, Tatsuya

2016-06-01

Iridium clusters nominally composed of 15, 30 or 60 atoms were size-selectively synthesized within OH-terminated poly(amidoamine) dendrimers of generation 6. Spectroscopic characterization revealed that the Ir clusters were partially oxidized. All the Ir clusters efficiently converted 2-nitrobenzaldehyde to anthranil and 2-aminobenzaldehyde under atmospheric hydrogen at room temperature in toluene via selective hydrogenation of the NO2 group. The selectivity toward 2-aminobenzaldehyde over anthranil was improved with the reduction of the cluster size. The improved selectivity is ascribed to more efficient reduction than intramolecular heterocyclization of a hydroxylamine intermediate on smaller clusters that have a higher Ir(0)-phase population on the surface.Iridium clusters nominally composed of 15, 30 or 60 atoms were size-selectively synthesized within OH-terminated poly(amidoamine) dendrimers of generation 6. Spectroscopic characterization revealed that the Ir clusters were partially oxidized. All the Ir clusters efficiently converted 2-nitrobenzaldehyde to anthranil and 2-aminobenzaldehyde under atmospheric hydrogen at room temperature in toluene via selective hydrogenation of the NO2 group. The selectivity toward 2-aminobenzaldehyde over anthranil was improved with the reduction of the cluster size. The improved selectivity is ascribed to more efficient reduction than intramolecular heterocyclization of a hydroxylamine intermediate on smaller clusters that have a higher Ir(0)-phase population on the surface. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01460g

Surface characteristics and electrochemical corrosion behavior of NiTi alloy coated with IrO2.

PubMed

Li, M; Wang, Y B; Zhang, X; Li, Q H; Liu, Q; Cheng, Y; Zheng, Y F; Xi, T F; Wei, S C

2013-01-01

The aim of this work is to investigate the surface characteristics and corrosion behavior of NiTi (50.6 at.% Ni) shape memory alloy coated by a ceramic-like and highly biocompatible material, iridium oxide (IrO2). IrO2 coatings were prepared by thermal decomposition of H2IrCl6 · 6H2O precursor solution at the temperature of 300 °C, 400 °C and 500 °C, respectively. The surface morphology and microstructure of the coatings were investigated by scanning electron microscope (SEM) and glancing angle X-ray diffraction (GAXRD). X-ray photoelectron spectroscopy (XPS) was employed to determine the surface elemental composition. Corrosion resistance property of the coated samples was studied in a simulated body fluid at 37±1 °C by electrochemical method. It was found that the morphology and microstructure of the coatings were closely related to the oxidizing temperatures. A relatively smooth, intact and amorphous coating was obtained when the H2IrCl6·6H2O precursor solution (0.03 mol/L) was thermally decomposed at 300 °C for 0.5 h. Compared with the bare NiTi alloy, IrO2 coated samples exhibited better corrosion resistance behavior to some extent. Copyright © 2012 Elsevier B.V. All rights reserved.

Crystal growth, structure determination and magnetism of a new m=3, n=1 member of the A3 n+3 mA' nB3 m+ nO 9 m+6 n family of oxides: 12R-Ba 12Rh 9.25Ir 1.75O 33

NASA Astrophysics Data System (ADS)

Stitzer, Katharine E.; El Abed, Ahmed; Darriet, Jacques; zur Loye, Hans-Conrad

2004-04-01

Single crystals of a new Ba-Rh-Ir-O oxide were grown from a molten potassium carbonate flux. The new compound, Ba 12Rh 9.25Ir 1.75O 33, is structurally related to the 2H-hexagonal perovskite structure and contains pseudo one-dimensional chains of alternating units of ten face-sharing (Rh/Ir)O 6 octahedra and one (Rh/Ir)O 6 trigonal prism. The magnetic susceptibility of Ba 12Rh 9.25Ir 1.75O 33 is featureless, indicating the absence of magnetic order. The oxide is a semiconductor with a room temperature resistance of 280 Ω.

Preparation of Ti/IrO2 Anode with Low Iridium Content by Thermal Decomposition Process: Electrochemical removal of organic pollutants in water

NASA Astrophysics Data System (ADS)

Yaqub, Asim; Isa, Mohamed Hasnain; Ajab, Huma; Kutty, S. R. M.; Ezechi, Ezerie H.; Farooq, Robina

2018-04-01

In this study IrO2 (Iridium oxide) was coated onto a titanium plate anode from a dilute (50 mg/10 ml) IrCl3×H2O salt solution. Coating was done at high temperature (550∘C) using thermal decomposition. Surface morphology and characteristics of coated surface of Ti/IrO2 anode were examined by FESEM and XRD. The coated anode was applied for electrochemical removal of organic pollutants from synthetic water samples in 100 mL compartment of batch electrochemical cell. About 50% COD removal was obtained at anode prepared with low Ir content solution while 72% COD removal was obtained with anode prepared at high Ir content. Maximum COD removal was obtained at 10 mA/cm2 current density.

A dual-waveband dynamic IR scene projector based on DMD

NASA Astrophysics Data System (ADS)

Hu, Yu; Zheng, Ya-wei; Gao, Jiao-bo; Sun, Ke-feng; Li, Jun-na; Zhang, Lei; Zhang, Fang

2016-10-01

Infrared scene simulation system can simulate multifold objects and backgrounds to perform dynamic test and evaluate EO detecting system in the hardware in-the-loop test. The basic structure of a dual-waveband dynamic IR scene projector was introduced in the paper. The system's core device is an IR Digital Micro-mirror Device (DMD) and the radiant source is a mini-type high temperature IR plane black-body. An IR collimation optical system which transmission range includes 3-5μm and 8-12μm is designed as the projection optical system. Scene simulation software was developed with Visual C++ and Vega soft tools and a software flow chart was presented. The parameters and testing results of the system were given, and this system was applied with satisfying performance in an IR imaging simulation testing.

IR780 based nanomaterials for cancer imaging and photothermal, photodynamic and combinatorial therapies.

PubMed

Alves, Cátia G; Lima-Sousa, Rita; de Melo-Diogo, Duarte; Louro, Ricardo O; Correia, Ilídio J

2018-05-05

IR780, a molecule with a strong optical absorption and emission in the near infrared (NIR) region, is receiving an increasing attention from researchers working in the area of cancer treatment and imaging. Upon irradiation with NIR light, IR780 can produce reactive oxygen species as well as increase the body temperature, thus being a promising agent for application in cancer photodynamic and photothermal therapy. However, IR780's poor water solubility, fast clearance, acute toxicity and low tumor uptake may limit its use. To overcome such issues, several types of nanomaterials have been used to encapsulate and deliver IR780 to tumor cells. This mini-review is focused on the application of IR780 based nanostructures for cancer imaging, and photothermal, photodynamic and combinatorial therapies. Copyright © 2018 Elsevier B.V. All rights reserved.

Variable noninnocence of substituted azobis(phenylcyanamido)diruthenium complexes.

PubMed

Choudhuri, Mohommad M R; Behzad, Mahdi; Al-Noaimi, Mousa; Yap, Glenn P A; Kaim, Wolfgang; Sarkar, Biprajit; Crutchley, Robert J

2015-02-16

The synthetic chemistry of substituted 4,4'-azobis(phenylcyanamide) ligands was investigated, and the complexes [{Ru(tpy)(bpy)}2(μ-L)][PF6]2, where L = 2,2':5,5'-tetramethyl-4,4'-azobis(phenylcyanamido) (Me4adpc(2-)), 2,2'-dimethyl-4,4'-azobis(phenylcyanamido) (Me2adpc(2-)), unsubstituted (adpc(2-)), 3,3'-dichloro-4,4'-azobis(phenylcyanamido) (Cl2adpc(2-)), and 2,2':5,5'-tetrachloro-4,4'-azobis(phenylcyanamido) (Cl4adpc(2-)), were prepared and characterized by cyclic voltammetry and vis-near-IR (NIR) and IR spectroelectrochemistry. The room temperature electron paramagnetic resonance spectrum of [{Ru(tpy)(bpy)}2(μ-Me4adpc)](3+) showed an organic radical signal and is consistent with an oxidation-state description [Ru(II), Me4adpc(•-), Ru(II)](3+), while that of [{Ru(tpy)(bpy)}2(μ-Cl2adpc)](3+) at 10 K showed a low-symmetry Ru(III) signal, which is consistent with the description [Ru(III), Cl2adpc(2-), Ru(II)](3+). IR spectroelectrochemistry data suggest that [{Ru(tpy)(bpy)}2(μ-adpc)](3+) is delocalized and [{Ru(tpy)(bpy)}2(μ-Cl2adpc)](3+) and [{Ru(tpy)(bpy)}2(μ-Cl4adpc)](3+) are valence-trapped mixed-valence systems. A NIR absorption band that is unique to all [{Ru(tpy)(bpy)}2(μ-L)](3+) complexes is observed; however, its energy and intensity vary depending on the nature of the bridging ligand and, hence, the complexes' oxidation-state description.

The effect of convection on infrared detection by antennal warm cells in the bloodsucking bug Rhodnius prolixus.

PubMed

Tichy, Harald; Zopf, Lydia M

2015-04-01

Previous work revealed that bloodsucking bugs can discriminate between oscillating changes in infrared (IR) radiation and air temperature (T) using two types of warm cells located in peg-in-pit sensilla and tapered hairs (Zopf LM, Lazzari CR, Tichy H. J Neurophysiol 111: 1341-1349, 2014). These two stimuli are encoded and discriminated by the response quotient of the two warm cell types. IR radiation stimulates the warm cell in the peg-in-pit sensillum more strongly than that in the tapered hair. T stimuli evoke the reverse responses; they stimulate the latter more strongly than the former. In nature, IR and T cues are always present with certain radiation intensities and air temperatures, here referred to as background IR radiation and background T. In this article, we found that the response quotient permits the discrimination of IR and T oscillations even in the presence of different backgrounds. We show that the two warm cells respond well to IR oscillations if the background T operates by natural convection but poorly at forced convection, even if the background T is higher than at natural convection. Background IR radiation strongly affects the responses to T oscillations: the discharge rates of both warm cells are higher the higher the power of the IR background. We compared the warm cell responses with the T measured inside small model objects shaped like a cylinder, a cone, or a disc. The experiments indicate that passive thermal effects of the sense organs rather than intrinsic properties of the sensory cells are responsible for the observed results. Copyright © 2015 the American Physiological Society.

Models for Temperature and Composition in Uranus from Spitzer, Herschel and Ground-Based Infrared through Millimeter Observations

NASA Astrophysics Data System (ADS)

Orton, Glenn; Fletcher, Leigh; Feuchtgruber, Helmut; Lellouch, Emmanuel; Moreno, Raphael; Hartogh, Paul; Jarchow, Christopher; Swinyard, Bruce; Moses, Julianne; Burgdorf, Martin; Hammel, Heidi; Line, Michael; Mainzer, Amy; Hofstadter, Mark; Sandell, Goran; Dowell, Charles

2014-05-01

Photometric and spectroscopic observations of Uranus were combined to create self-consistent models of its global-mean temperature profile, bulk composition, and vertical distribution of gases. These were derived from a suite of spacecraft and ground-based observations that includes the Spitzer IRS, and the Herschel HIFI, PACS and SPIRE instruments, together with ground-based observations from UKIRT and CSO. Observations of the collision-induced absorption of H2 have constrained the temperature structure in the troposphere; this was possible up to atmospheric pressures of ~2 bars. Temperatures in the stratosphere were constrained by H2 quadrupole line emission. We coupled the vertical distribution of CH4 in the stratosphere of Uranus with models for the vertical mixing in a way that is consistent with the mixing ratios of hydrocarbons whose abundances are influenced primarily by mixing rather than chemistry. Spitzer and Herschel data constrain the abundances of CH3, CH4, C2H2, C2H6, C3H4, C4H2, H2O and CO2. The Spitzer IRS data, in concert with photochemical models, show that the atmosphere the homopause is much higher pressures than for the other outer planets, with the predominant trace constituents for pressures lower than 10 μbar being H2O and CO2. At millimeter wavelengths, there is evidence that an additional opacity source is required besides the H2 collision-induced absorption and the NH3 absorption needed to match the microwave spectrum; this can reasonably (but not uniquely) be attributed to H2S. These models will be made more mature by consideration of spatial variability from Voyager IRIS and more recent spatially resolved imaging and mapping from ground-based observatories. The model is of 'programmatic' interest because it serves as a calibration source for Herschel instruments, and it provides a starting point for planning future spacecraft investigations of the atmosphere of Uranus.

Infrared Spectral Energy Distribution Decomposition of WISE-selected, Hyperluminous Hot Dust-obscured Galaxies

NASA Astrophysics Data System (ADS)

Fan, Lulu; Han, Yunkun; Nikutta, Robert; Drouart, Guillaume; Knudsen, Kirsten K.

2016-06-01

We utilize a Bayesian approach to fit the observed mid-IR-to-submillimeter/millimeter spectral energy distributions (SEDs) of 22 WISE-selected and submillimeter-detected, hyperluminous hot dust-obscured galaxies (Hot DOGs), with spectroscopic redshift ranging from 1.7 to 4.6. We compare the Bayesian evidence of a torus plusgraybody (Torus+GB) model with that of a torus-only (Torus) model and find that the Torus+GB model has higher Bayesian evidence for all 22 Hot DOGs than the torus-only model, which presents strong evidence in favor of the Torus+GB model. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot DOGs into torus and cold dust components. The main results are as follows. (1) Hot DOGs in our submillimeter-detected sample are hyperluminous ({L}{IR}≥slant {10}13{L}⊙ ), with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, contributing on average ˜ 24% of total IR luminosity. (2) Compared to QSO and starburst SED templates, the median SED of Hot DOGs shows the highest luminosity ratio between mid-IR and submillimeter at rest frame, while it is very similar to that of QSOs at ˜ 10{--}50 μ {{m}}, suggesting that the heating sources of Hot DOGs should be buried AGNs. (3) Hot DOGs have high dust temperatures ({T}{dust}˜ 72 K) and high IR luminosity of cold dust. The {T}{dust}{--}{L}{IR} relation of Hot DOGs suggests that the increase in IR luminosity for Hot DOGs is mostly due to the increase of the dust temperature, rather than dust mass. Hot DOGs have lower dust masses than submillimeter galaxies (SMGs) and QSOs within a similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot DOGs can be expected by their relatively high dust temperatures. (4) Hot DOGs have high dust-covering factors (CFs), which deviate from the previously proposed trend of the dust CF decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot DOGs by employing a physical model of galaxy evolution. This result suggests that Hot DOGs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolutions of massive galaxies, transforming them from the dusty starburst-dominated phase to the optically bright QSO phase.

Role of insulin resistance and adipocytokines on serum alanine aminotransferase in obese patients with type 2 diabetes mellitus.

PubMed

de Luis, D A; Aller, R; Izaola, O; Gonzalez Sagrado, M; Conde, R; de la Fuente, B

2013-01-01

The aim of our study was to study the association of insulin resistance expressed by HOMA and adipokines in obese type 2 diabetic patients with or without hyper-transaminasemia. A population of 72 obese patients with type 2 diabetes mellitus was analyzed. HOMA-IR was calculated as indicator of insulin-resistance. Adipocytokines blood levels were measured. Patients were classified as group I (n=37) when serum ALT activity was normal or group II (NAFLD patients: n=35) when serum ALT activity was greater than the median value of the group (≥ 28 UI/L). In NAFLD group, BMI, weight, fat mass, waist to hip ratio, waist circumference, triglycerides, HOMA and insulin levels were higher than control group. In the logistic regression analysis with a dependent variable (ALT) and the statistical univariant variables as independent variables, the HOMA-IR remained in the model, with an Odd's ratio of 1.21 (CI:95%: 1.11-1.35) to have a high ALT level with each 1 unit of HOMA-IR adjusted by age, sex, weight, and dietary intake. Some metabolic parameters are associated with elevated ALT in female obese patients. However, adjusted by other variables, only insulin resistance remained associated.

Thermal structure of the Martian atmosphere retrieved from the IR spectrometry in the 15 μm CO2 band: input to MIRA

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Formisano, V.; Grassi, D.; Igantiev, N. I.; Moroz, V. I.

This paper describes one of the sources of the data concerning the thermal structure of the Martian atmosphere, based on the thermal IR spectrometry method. It allows to investigate the Martian atmosphere below 55 km by retrieving the temperature profiles from the 15 μm CO2 band. This approach enables to reach the vertical resolution of several kilometers and the temperature accuracy of several Kelvins. An aerosol abundance, which influences the temperature profile, is obtained from the continuum of the same spectrum parallel with the temperature profile and is taken into account in the temperature retrieval procedure in a self consistent way. Although this method has the limited vertical resolution, it possesses a significant advantage: the thermal IR spectrometry allows to monitor the temperature profiles with a good coverage both in space and local time. The Planetary Fourier spectrometer on board of Mars Express has the spectral range from 250 to 8000 cm-1 and a high spectral resolution of about 2 cm-1. Vertical temperature profiles retrieval is one of the main scientific goals of the experiment. The important data are expected to be obtained on the vertical thermal structure of the atmosphere, and its dependence on latitude, longitude, season, local time, clouds and dust loadings. These results should give a significant input in the future MIRA, being included in the Chapter “Structure of the atmosphere from the surface to 100 km”.

Two-wavelength mid-IR diagnostic for temperature and n-dodecane concentration in an aerosol shock tube

NASA Astrophysics Data System (ADS)

Klingbeil, A. E.; Jeffries, J. B.; Davidson, D. F.; Hanson, R. K.

2008-11-01

A two-wavelength, mid-IR optical absorption diagnostic is developed for simultaneous temperature and n-dodecane vapor concentration measurements in an aerosol-laden shock tube. FTIR absorption spectra for the temperature range 323 to 773 K are used to select the two wavelengths (3409.0 and 3432.4 nm). Shock-heated mixtures of n-dodecane vapor in argon are then used to extend absorption cross section data at these wavelengths to 1322 K. The sensor is used to validate a model of the post-evaporation temperature and pressure of shock-heated fuel aerosol, which can ultimately be used for the study of the chemistry of low-vapor-pressure compounds and fuel blends. The signal-to-noise ratio of the temperature and concentration are ˜20 and ˜30, respectively, illustrating the sensitivity of this diagnostic. The good agreement between model and measurement provide confidence in the use of this aerosol shock tube to provide well-known thermodynamic conditions. At high temperatures, pseudo-first-order decomposition rates are extracted from time-resolved concentration measurements, and data from vapor and aerosol shocks are found to be in good agreement. Notably, the n-dodecane concentration measurements exhibit slower decomposition than predicted by models using two published reaction mechanisms, illustrating the need for further kinetic studies of this hydrocarbon. These results demonstrate the potential of multi-wavelength mid-IR laser sensors for hydrocarbon measurements in environments with time-varying temperature and concentration.

Visualizing Chemistry with Infrared Imaging

ERIC Educational Resources Information Center

Xie, Charles

2011-01-01

Almost all chemical processes release or absorb heat. The heat flow in a chemical system reflects the process it is undergoing. By showing the temperature distribution dynamically, infrared (IR) imaging provides a salient visualization of the process. This paper presents a set of simple experiments based on IR imaging to demonstrate its enormous…

Temperature dependence of terahertz optical properties of LBO and perspectives of applications in down-converters

NASA Astrophysics Data System (ADS)

Nikolaev, N. A.; Andreev, Yu. M.; Kononova, N. G.; Lanskii, G. V.; Mamrashev, A. A.; Antsygin, V. D.; Kokh, K. A.; Kokh, A. E.

2018-01-01

Lithium triborate LiB3O5 (LBO) crystals are widely used for frequency conversion of the near-IR lasers within main transparency windows. Their optical properties at these wavelengths are well studied. However, very little work has been published on the properties in the terahertz (THz) range. There was a lack of data on the refractive indices, the absorption coefficients spectra and their temperature dispersions. There are no reports of THz applications. Present work reveals all these topics including the prospects for use LBO crystals as down-converters of the near-IR lasers radiation. Optically finished samples of flux-grown LBO crystals were studied by THz-TDS. The refractive index dispersions were recorded and then approximated in the form of Sellmeier equations for the temperatures of 300 and 81 K. The phase-matching curves for the IR-THz and THz-THz frequency conversions were calculated. It was found that the absorption coefficients of LBO decrease significantly with cooling to cryogenic temperatures, but the overall character of optical properties changes is intricated. Experimental results are discussed in detail considering potential characteristics of THz down-converters.

Influence of temperature on water and aqueous glucose absorption spectra in the near- and mid-infrared regions at physiologically relevant temperatures.

PubMed

Jensen, Peter Snoer; Bak, Jimmy; Andersson-Engels, Stefan

2003-01-01

Near- and mid-infrared absorption spectra of pure water and aqueous 1.0 g/dL glucose solutions in the wavenumber range 8000-950 cm-1 were measured in the temperature range 30-42 degrees C in steps of 2 degrees C. Measurements were carried out with an FT-IR spectrometer and a variable pathlength transmission cell controlled within 0.02 degree C. Pathlengths of 50 microns and 0.4 mm were used in the mid- and near-infrared spectral region, respectively. Difference spectra were used to determine the effect of temperature on the water spectra quantitatively. These spectra were obtained by subtracting the 37 degrees C water spectrum from the spectra measured at other temperatures. The difference spectra reveal that the effect of temperature is highest in the vicinity of the strong absorption bands, with a number of isosbestic points with no temperature dependence and relatively flat plateaus in between. On the basis of these spectra, prospects for and limitations on data analysis for infrared diagnostic methods are discussed. As an example, the absorptive properties of glucose were studied in the same temperature range in order to determine the effect of temperature on the spectral shape of glucose. The change in water absorption associated with the addition of glucose has also been studied. An estimate of these effects is given and is related to the expected level of infrared signals from glucose in humans.

Dryland pasture and crop conditions as seen by HCMM. [Washita River watershed

NASA Technical Reports Server (NTRS)

Harlan, J. C. (Principal Investigator); Rosenthal, W. D.; Blanchard, B. J.

1981-01-01

The antecedent precipitation index (API) was related to surface temperatures as measured from the NASA C-130 and HCMM thermal data. Significant results from the aircraft flight in May 1978, include: (1) canopy temperature were measured accurately remotely; (2) pasture surface temperatures were related to pasture and wheat soil moisture conditions; (3) no relationship was developed with that data set between wheat yield and thermal infrared data due to a lack of moisture stress during the measurement period; and (4) lake surface temperatures were useful in normalizing the thermal IR data. Results from HCMM also suggested a relationship between thermal IR data and antecedent precipitation index. While HCMM was adequate in detecting relative soil moisture differences, the overpass timing was infrequent and prevented detailed analysis of the API/thermal relationship.

Assessing the role of the medial preoptic area in ethanol-induced hypothermia.

PubMed

Westerman, Ashley T; Roma, Peter G; Price, Rebecca C; Dominguez, Juan M

2010-05-07

Administration of ethanol produces hypothermia. The preoptic area/anterior hypothalamus (POA/AH) contains warm- and cold-sensitive neurons that are important for temperature regulation. The present study evaluated the effect of ethanol on Fos immunoreactivity (Fos-ir) in the medial preoptic area (MPOA) and the effect of lesions to the MPOA on ethanol-induced hypothermia. Rats receiving 1.5-g/kg ethanol showed an increase in Fos-ir in the MPOA. However, lesions to the MPOA did not affect core body temperature. These findings indicate that ethanol increases neural activity in the MPOA, but this increased activity does not influence ethanol-induced changes in core body temperature. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Non-contact passive temperature measuring system and method of operation using micro-mechanical sensors

DOEpatents

Thundat, Thomas G.; Oden, Patrick I.; Datskos, Panagiotis G.

2000-01-01

A non-contact infrared thermometer measures target temperatures remotely without requiring the ratio of the target size to the target distance to the thermometer. A collection means collects and focusses target IR radiation on an IR detector. The detector measures thermal energy of the target over a spectrum using micromechanical sensors. A processor means calculates the collected thermal energy in at least two different spectral regions using a first algorithm in program form and further calculates the ratio of the thermal energy in the at least two different spectral regions to obtain the target temperature independent of the target size, distance to the target and emissivity using a second algorithm in program form.

Variable Emittance Electrochromic Devices for Satellite Thermal Control

NASA Astrophysics Data System (ADS)

Demiryont, Hulya; Shannon, Kenneth C.

2007-01-01

An all-solid-state electrochromic device (ECD) was designed for electronic variable emissivity (VE) control. In this paper, a low weight (5g/m2) electrochromic thermal control device, the EclipseVEECD™, is detailed as a viable thermal control system for spacecraft outer surface temperatures. Discussion includes the technology's performance, satellite applications, and preparations for space based testing. This EclipseVEECD™ system comprises substrate/mirror electrode/active element/IR transparent electrode layers. This system tunes and modulates reflection/emittance from 5 μm to 15 μm region. Average reflectance/emittance modulation of the system from the 400 K to 250 K region is about 75%, while at room temperature (9.5 micron) reflectance/emittance is around 90%. Activation voltage of the EclipseVEECD™ is around ±1 Volt. The EclipseVEECD™ can be used as a smart thermal modulator for the thermal control of satellites and spacecraft by monitoring and adjusting the amount of energy emitted from the outer surfaces. The functionality of the EclipseVEECD™ was successfully demonstrated in vacuum using a multi-purpose heat dissipation/absorption test module, the EclipseHEAT™. The EclipseHEAT™ has been successfully flight checked and integrated onto the United States Naval Alchemy MidSTAR satellite, scheduled to launch December 2006.

Photochemical route to actinide-transition metal bonds: synthesis, characterization and reactivity of a series of thorium and uranium heterobimetallic complexes.

PubMed

Ward, Ashleigh L; Lukens, Wayne W; Lu, Connie C; Arnold, John

2014-03-05

A series of actinide-transition metal heterobimetallics has been prepared, featuring thorium, uranium, and cobalt. Complexes incorporating the binucleating ligand N[ο-(NHCH2P(i)Pr2)C6H4]3 with either Th(IV) (4) or U(IV) (5) and a carbonyl bridged [Co(CO)4](-) unit were synthesized from the corresponding actinide chlorides (Th: 2; U: 3) and Na[Co(CO)4]. Irradiation of the resulting isocarbonyls with ultraviolet light resulted in the formation of new species containing actinide-metal bonds in good yields (Th: 6; U: 7); this photolysis method provides a new approach to a relatively unusual class of complexes. Characterization by single-crystal X-ray diffraction revealed that elimination of the bridging carbonyl and formation of the metal-metal bond is accompanied by coordination of a phosphine arm from the N4P3 ligand to the cobalt center. Additionally, actinide-cobalt bonds of 3.0771(5) Å and 3.0319(7) Å for the thorium and uranium complexes, respectively, were observed. The solution-state behavior of the thorium complexes was evaluated using (1)H, (1)H-(1)H COSY, (31)P, and variable-temperature NMR spectroscopy. IR, UV-vis/NIR, and variable-temperature magnetic susceptibility measurements are also reported.

Photochemical route to actinide-transition metal bonds: synthesis, characterization and reactivity of a series of thorium and uranium heterobimetallic complexes

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

Ward, Ashleigh; Lukens, Wayne; Lu, Connie

2014-04-01

A series of actinide-transition metal heterobimetallics has been prepared, featuring thorium, uranium and cobalt. Complexes incorporating the binucleating ligand N[-(NHCH2PiPr2)C6H4]3 and Th(IV) (4) or U(IV) (5) with a carbonyl bridged [Co(CO)4]- unit were synthesized from the corresponding actinide chlorides (Th: 2; U: 3) and Na[Co(CO)4]. Irradiation of the isocarbonyls with ultraviolet light resulted in the formation of new species containing actinide-metal bonds in good yields (Th: 6; U: 7); this photolysis method provides a new approach to a relatively rare class of complexes. Characterization by single-crystal X-ray diffraction revealed that elimination of the bridging carbonyl is accompanied by coordination ofmore » a phosphine arm from the N4P3 ligand to the cobalt center. Additionally, actinide-cobalt bonds of 3.0771(5) and 3.0319(7) for the thorium and uranium complexes, respectively, were observed. The solution state behavior of the thorium complexes was evaluated using 1H, 1H-1H COSY, 31P and variable-temperature NMR spectroscopy. IR, UV-Vis/NIR, and variable-temperature magnetic susceptibility measurements are also reported.« less

THE ROLE OF STAR FORMATION AND AN AGN IN DUST HEATING OF z = 0.3–2.8 GALAXIES. I. EVOLUTION WITH REDSHIFT AND LUMINOSITY

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

Kirkpatrick, Allison; Pope, Alexandra; Sajina, Anna

2015-11-20

We characterize infrared spectral energy distributions of 343 (ultra)luminous infrared galaxies from z = 0.3–2.8. We diagnose the presence of an active galactic nucleus (AGN) by decomposing individual Spitzer mid-IR spectroscopy into emission from star formation and an AGN-powered continuum; we classify sources as star-forming galaxies (SFGs), AGNs, or composites. Composites comprise 30% of our sample and are prevalent at faint and bright S{sub 24}, making them an important source of IR AGN emission. We combine spectroscopy with multiwavelength photometry, including Herschel imaging, to create three libraries of publicly available templates (2–1000 μm). We fit the far-IR emission using amore » two-temperature modified blackbody to measure cold and warm dust temperatures (T{sub c} and T{sub w}). We find that T{sub c} does not depend on mid-IR classification, while T{sub w} shows a notable increase as the AGN grows more luminous. We measure a quadratic relationship between mid-IR AGN emission and total AGN contribution to L{sub IR}. AGNs, composites, and SFGs separate in S{sub 8}/S{sub 3.6} and S{sub 250}/S{sub 24}, providing a useful diagnostic for estimating relative amounts of these sources. We estimate that >40% of IR-selected samples host an AGN, even at faint selection thresholds (S{sub 24} > 100 μJy). Our decomposition technique and color diagnostics are relevant given upcoming observations with the James Webb Space Telescope.« less

CFA-4 - a fluorinated metal-organic framework with exchangeable interchannel cations.

PubMed

Fritzsche, J; Grzywa, M; Denysenko, D; Bon, V; Senkovska, I; Kaskel, S; Volkmer, D

2017-05-23

The syntheses and crystal structures of the fluorinated linker 1,4-bis(3,5-bis(trifluoromethyl)-1H-pyrazole-4-yl)benzene (H 2 -tfpb; 1) and the novel metal-organic framework family M[CFA-4] (Coordination Framework Augsburg University-4), M[Cu 5 (tfpb) 3 ] (M = Cu(i), K, Cs, Ca(0.5)), are described. The ligand 1 is fully characterized by single crystal X-ray diffraction, photoluminescence-, NMR-, IR spectroscopy, and mass spectrometry. The copper(i)-containing MOF crystallizes in the hexagonal crystal system within the chiral space group P6 3 22 (no. 182) and the unit cell parameters are as follows: a = 23.630(5) Å, c = 41.390(5) Å, V = 20 015(6) Å 3 . M[CFA-4] features a porous 3-D structure constructed from pentanuclear copper(i) secondary building units {Cu(pz) 6 } - (pz = pyrazolate). Cu(I)[CFA-4] is fully characterized by synchrotron single crystal X-ray diffraction, thermogravimetric analysis, variable temperature powder X-ray diffraction, IR spectroscopy, photoluminescence and gas sorption measurements. Moreover, thermal stability and gas sorption properties of K[CFA-4] and Cu(I)[CFA-4] are compared.

Uncooled radiometric camera performance

NASA Astrophysics Data System (ADS)

Meyer, Bill; Hoelter, T.

1998-07-01

Thermal imaging equipment utilizing microbolometer detectors operating at room temperature has found widespread acceptance in both military and commercial applications. Uncooled camera products are becoming effective solutions to applications currently using traditional, photonic infrared sensors. The reduced power consumption and decreased mechanical complexity offered by uncooled cameras have realized highly reliable, low-cost, hand-held instruments. Initially these instruments displayed only relative temperature differences which limited their usefulness in applications such as Thermography. Radiometrically calibrated microbolometer instruments are now available. The ExplorIR Thermography camera leverages the technology developed for Raytheon Systems Company's first production microbolometer imaging camera, the Sentinel. The ExplorIR camera has a demonstrated temperature measurement accuracy of 4 degrees Celsius or 4% of the measured value (whichever is greater) over scene temperatures ranges of minus 20 degrees Celsius to 300 degrees Celsius (minus 20 degrees Celsius to 900 degrees Celsius for extended range models) and camera environmental temperatures of minus 10 degrees Celsius to 40 degrees Celsius. Direct temperature measurement with high resolution video imaging creates some unique challenges when using uncooled detectors. A temperature controlled, field-of-view limiting aperture (cold shield) is not typically included in the small volume dewars used for uncooled detector packages. The lack of a field-of-view shield allows a significant amount of extraneous radiation from the dewar walls and lens body to affect the sensor operation. In addition, the transmission of the Germanium lens elements is a function of ambient temperature. The ExplorIR camera design compensates for these environmental effects while maintaining the accuracy and dynamic range required by today's predictive maintenance and condition monitoring markets.

Modeling of mid-infrared quantum cascade lasers: The role of temperature and operating field strength on the laser performance

NASA Astrophysics Data System (ADS)

Yousefvand, Hossein Reza

2017-07-01

In this paper a self-consistent numerical approach to study the temperature and bias dependent characteristics of mid-infrared (mid-IR) quantum cascade lasers (QCLs) is presented which integrates a number of quantum mechanical models. The field-dependent laser parameters including the nonradiative scattering times, the detuning and energy levels, the escape activation energy, the backfilling excitation energy and dipole moment of the optical transition are calculated for a wide range of applied electric fields by a self-consistent solution of Schrodinger-Poisson equations. A detailed analysis of performance of the obtained structure is carried out within a self-consistent solution of the subband population rate equations coupled with carrier coherent transport equations through the sequential resonant tunneling, by taking into account the temperature and bias dependency of the relevant parameters. Furthermore, the heat transfer equation is included in order to calculate the carrier temperature inside the active region levels. This leads to a compact predictive model to analyze the temperature and electric field dependent characteristics of the mid-IR QCLs such as the light-current (L-I), electric field-current (F-I) and core temperature-electric field (T-F) curves. For a typical mid-IR QCL, a good agreement was found between the simulated temperature-dependent L-I characteristic and experimental data, which confirms validity of the model. It is found that the main characteristics of the device such as output power and turn-on delay time are degraded by interplay between the temperature and Stark effects.

Study of optical techniques for the Ames unitary wind tunnel. Part 5: Infrared imagery

NASA Technical Reports Server (NTRS)

Lee, George

1992-01-01

A survey of infrared thermography for aerodynamics was made. Particular attention was paid to boundary layer transition detection. IR thermography flow visualization of 2-D and 3-D separation was surveyed. Heat transfer measurements and surface temperature measurements were also covered. Comparisons of several commercial IR cameras were made. The use of a recently purchased IR camera in the Ames Unitary Plan Wind Tunnels was studied. Optical access for these facilities and the methods to scan typical models was investigated.

Divergent copies of the large inverted repeat in the chloroplast genomes of ulvophycean green algae.

PubMed

Turmel, Monique; Otis, Christian; Lemieux, Claude

2017-04-20

The chloroplast genomes of many algae and almost all land plants carry two identical copies of a large inverted repeat (IR) sequence that can pair for flip-flop recombination and undergo expansion/contraction. Although the IR has been lost multiple times during the evolution of the green algae, the underlying mechanisms are still largely unknown. A recent comparison of IR-lacking and IR-containing chloroplast genomes of chlorophytes from the Ulvophyceae (Ulotrichales) suggested that differential elimination of genes from the IR copies might lead to IR loss. To gain deeper insights into the evolutionary history of the chloroplast genome in the Ulvophyceae, we analyzed the genomes of Ignatius tetrasporus and Pseudocharacium americanum (Ignatiales, an order not previously sampled), Dangemannia microcystis (Oltmannsiellopsidales), Pseudoneochloris marina (Ulvales) and also Chamaetrichon capsulatum and Trichosarcina mucosa (Ulotrichales). Our comparison of these six chloroplast genomes with those previously reported for nine ulvophyceans revealed unsuspected variability. All newly examined genomes feature an IR, but remarkably, the copies of the IR present in the Ignatiales, Pseudoneochloris, and Chamaetrichon diverge in sequence, with the tRNA genes from the rRNA operon missing in one IR copy. The implications of this unprecedented finding for the mechanism of IR loss and flip-flop recombination are discussed.

New mixed valence defect dicubane cobalt(II)/cobalt(III) complex: Synthesis, crystal structure, photoluminescence and magnetic properties

NASA Astrophysics Data System (ADS)

Coban, Mustafa Burak; Gungor, Elif; Kara, Hulya; Baisch, Ulrich; Acar, Yasemin

2018-02-01

A new defect dicubane cobalt(II)/cobalt(III), [(CoII2CoIII2L42(H2O)(CH3COO)(CH3COOH]. 4H2O complex (1) where H2L = [1-(3-hydroxypropyliminomethyl)naphthalene-2-ol], has been synthesized and characterized by element analysis, FT-IR, solid UV-Vis spectroscopy and single crystal X-ray diffraction. The crystal structure determination shows a cationic tetrameric arrangement consisting of a defect dicubane core with two missing vertexes. Each cobalt ion has a distorted octahedral geometry with six coordinate ordered CoII and CoIII ions. The solid state photoluminescence properties of complex (1) and its ligand H2L have been investigated under UV light at 349 nm in the visible region. H2L exhibits blue emission while complex (1) shows red emission at room temperature. Variable-temperature magnetic susceptibility measurements on the complex (1) in the range 2-300 K indicate an antiferromagnetic interaction.

Biomimetic synthesis of silver nanoparticles and evaluation of their catalytic activity towards degradation of methyl orange

NASA Astrophysics Data System (ADS)

Manjari Mishra, Pravat; Bihari Pani, Khirod

2017-11-01

This paper described the significant effect of process variables like reductant concentrations, substrate concentration, reaction pH and reaction temperature on the size, morphology and yield of the silver nanoparticles (AgNPs) synthesized using aqueous leaf extract of a medicinal plant Momordica charantia (Bitter guard). By means of UV-vis spectroscopy, XRD analysis, TEM analysis and Fluorescence analysis, it is observed that the reaction solution containing 10-3 M of AgNO3 of pH 5.3  +  10 ml of aqueous leaf extract at normal room temperature, was optimum for synthesis of stable, polydisperse, predominantly spherical AgNPs with average size of 12.15 nm. FT-IR and TEM studies confirmed the stability of AgNPs was due to the capping of phytoconstituents present in the leaf extract. The aqueous solution of leaf extract containing AgNPs showed remarkable catalytic activity towards degradation of methyl orange (MO) in aqueous medium.

In situ fabrication of quasi-free-standing epitaxial graphene nanoflakes on gold.

PubMed

Leicht, Philipp; Zielke, Lukas; Bouvron, Samuel; Moroni, Riko; Voloshina, Elena; Hammerschmidt, Lukas; Dedkov, Yuriy S; Fonin, Mikhail

2014-04-22

Addressing the multitude of electronic phenomena theoretically predicted for confined graphene structures requires appropriate in situ fabrication procedures yielding graphene nanoflakes (GNFs) with well-defined geometries and accessible electronic properties. Here, we present a simple strategy to fabricate quasi-free-standing GNFs of variable sizes, performing temperature programmed growth of graphene flakes on the Ir(111) surface and subsequent intercalation of gold. Using scanning tunneling microscopy (STM), we show that epitaxial GNFs on a perfectly ordered Au(111) surface are formed while maintaining an unreconstructed, singly hydrogen-terminated edge structure, as confirmed by the accompanying density functional theory (DFT) calculations. Using tip-induced lateral displacement of GNFs, we demonstrate that GNFs on Au(111) are to a large extent decoupled from the Au(111) substrate. The direct accessibility of the electronic states of a single GNF is demonstrated upon analysis of the quasiparticle interference patterns obtained by low-temperature STM. These findings open up an interesting playground for diverse investigations of graphene nanostructures with possible implications for device fabrication.

Prediction of the lifetime of nitrile-butadiene rubber by FT-IR.

PubMed

Kawashima, Tetsuya; Ogawa, Toshio

2005-12-01

A quantitative measurement method with FT-IR was proposed for a thermal degradation analysis of nitrile-butadiene rubber (NBR). An NBR film was prepared as a model sample on a barium fluoride (BaF2) crystal plate, which was subjected to a heat treatment. The absorbances of various functional groups were measured directly by FT-IR after thermal degradation at high temperatures. By measuring the absorbances, it was possible to readily determine quantitatively each of the functional groups after the degradation of NBR. By assuming that the NBR lifetime was the point at which the absorbance of a carbon-carbon double bond reaches 45% of that prior to thermal treatment, a method for predicting the lifetime of NBR heated below 150 degrees C was proposed, by using an Arrhenius plot of the heating time versus heating temperature.

Characterization of the Infrared/X-ray sub-second variability for the black-hole transient GX 339-4

NASA Astrophysics Data System (ADS)

Vincentelli, F. M.; Casella, P.; Maccarone, T. J.; Uttley, P.; Gandhi, P.; Belloni, T.; De Marco, B.; Russell, D. M.; Stella, L.; O'Brien, K.

2018-03-01

We present a detailed analysis of the X-ray/IR fast variability of the Black-Hole Transient GX 339-4 during its low/hard state in August 2008. Thanks to simultaneous high time-resolution observations made with the VLT and RXTE, we performed the first characterisation of the sub-second variability in the near-infrared band - and of its correlation with the X-rays - for a low-mass X-ray binary, using both time- and frequency-domain techniques. We found a power-law correlation between the X-ray and infrared fluxes when measured on timescales of 16 seconds, with a marginally variable slope, steeper than the one found on timescales of days at similar flux levels. We suggest the variable slope - if confirmed - could be due to the infrared flux being a non-constant combination of both optically thin and optically thick synchrotron emission from the jet, as a result of a variable self-absorption break. From cross spectral analysis we found an approximately constant infrared time lag of ≈0.1s, and a very high coherence of ˜90 per cent on timescales of tens of seconds, slowly decreasing toward higher frequencies. Finally, we report on the first detection of a linear rms-flux relation in the emission from a low-mass X-ray binary jet, on timescales where little correlation is found between the X-rays and the jet emission itself. This suggests that either the inflow variations and jet IR emission are coupled by a non-linear or time-variable transform, or that the IR rms-flux relation is not transferred from the inflow to the jet, but is an intrinsic property of emission processes in the jet.

Characterization of the infrared/X-ray subsecond variability for the black hole transient GX 339-4

NASA Astrophysics Data System (ADS)

Vincentelli, F. M.; Casella, P.; Maccarone, T. J.; Uttley, P.; Gandhi, P.; Belloni, T.; De Marco, B.; Russell, D. M.; Stella, L.; O'Brien, K.

2018-07-01

We present a detailed analysis of the X-ray/IR fast variability of the Black-Hole Transient GX 339-4 during its low/hard state in 2008 August. Thanks to simultaneous high time resolution observations made with the VLT and RXTE, we performed the first characterization of the subsecond variability in the near-infrared band - and of its correlation with the X-rays - for a low-mass X-ray binary, using both time- and frequency-domain techniques. We found a power-law correlation between the X-ray and infrared fluxes when measured on time-scales of 16 s, with a marginally variable slope, steeper than the one found on time-scales of days at similar flux levels. We suggest the variable slope - if confirmed - could be due to the infrared flux being a non-constant combination of both optically thin and optically thick synchrotron emission from the jet, as a result of a variable self-absorption break. From cross spectral analysis, we found an approximately constant infrared time lag of ≈0.1 s, and a very high coherence of ˜90 per cent on time-scales of tens of seconds, slowly decreasing towards higher frequencies. Finally, we report on the first detection of a linear rms-flux relation in the emission from a low-mass X-ray binary jet, on time-scales where little correlation is found between the X-rays and the jet emission itself. This suggests that either the inflow variations and jet IR emission are coupled by a non-linear or time-variable transform, or that the IR rms-flux relation is not transferred from the inflow to the jet, but is an intrinsic property of emission processes in the jet.

Validity and reliability of 6-a-side small-sided game locomotor performance in assessing physical fitness in football players.

PubMed

Stevens, Tom Gerardus Antonia; De Ruiter, Cornelis Johannes; Beek, Peter Jan; Savelsbergh, Geert Jozef Peter

2016-01-01

In order to determine whether small-sided game (SSG) locomotor performance can serve as a fitness indicator, we (1) compared 6-a-side (6v6) SSG-intensity of players varying in fitness and skill, (2) examined the relationship of the 6v6-SSG and Yo-Yo IR2 and (3) assessed the reliability of the 6v6-SSG. Thirty-three professional senior, 30 professional youth, 62 amateur and 16 professional woman football players performed 4 × 7 min 6v6-SSGs recorded by a Local Position Measurement system. A substantial subgroup (N = 113) also performed the Yo-Yo IR2. Forty-seven amateur players performed two or three 6v6-SSGs. No differences in 6v6-SSG time-motion variables were found between professional senior and professional youth players. Amateurs showed lower values than professional seniors on almost all time-motion variables (ES = 0.59-1.19). Women displayed lower high-intensity time-motion variables than all other subgroups. Total distance run during 6v6-SSG was only moderately related to Yo-Yo IR2 distance (r = 0.45), but estimated metabolic power, high speed (>14.4 km · h(-1)), high acceleration (>2 m · s(-2)), high power (>20 W · kg(-1)) and very high (35 W · kg(-1)) power showed higher correlations (r = 0.59-0.70) with Yo-Yo IR2 distance. Intraclass correlation coefficient values were higher for total distance (0.84) than other time-motion variables (0.74‒0.78). Although total distance and metabolic power during 6v6-SSG showed good reproducibility (coefficient of variation (CV) < 5%), CV was higher (8-14%) for all high-intensity time-motion variables. It was therefore concluded that standardised SSG locomotor performance cannot serve used as a valid and reliable fitness indicator for individual players.

DISCOVERING THE MISSING 2.2 < z < 3 QUASARS BY COMBINING OPTICAL VARIABILITY AND OPTICAL/NEAR-INFRARED COLORS

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

Wu Xuebing; Wang Ran; Bian Fuyan

2011-09-15

The identification of quasars in the redshift range 2.2 < z < 3 is known to be very inefficient because the optical colors of such quasars are indistinguishable from those of stars. Recent studies have proposed using optical variability or near-infrared (near-IR) colors to improve the identification of the missing quasars in this redshift range. Here we present a case study combining both methods. We select a sample of 70 quasar candidates from variables in Sloan Digital Sky Survey (SDSS) Stripe 82, which are non-ultraviolet excess sources and have UKIDSS near-IR public data. They are clearly separated into two partsmore » on the Y - K/g - z color-color diagram, and 59 of them meet or lie close to a newly proposed Y - K/g - z selection criterion for z < 4 quasars. Of these 59 sources, 44 were previously identified as quasars in SDSS DR7, and 35 of them are quasars at 2.2 < z < 3. We present spectroscopic observations of 14 of 15 remaining quasar candidates using the Bok 2.3 m telescope and the MMT 6.5 m telescope, and successfully identify all of them as new quasars at z = 2.36-2.88. We also apply this method to a sample of 643 variable quasar candidates with SDSS-UKIDSS nine-band photometric data selected from 1875 new quasar candidates in SDSS Stripe 82 given by Butler and Bloom based on the time-series selections, and find that 188 of them are probably new quasars with photometric redshifts at 2.2 < z < 3. Our results indicate that the combination of optical variability and optical/near-IR colors is probably the most efficient way to find 2.2 < z < 3 quasars and is very helpful for constructing a complete quasar sample. We discuss its implications for ongoing and upcoming large optical and near-IR sky surveys.« less

Iridium clusters in KLTL zeolite: Structure and catalytic selectivity for n-hexane aromatization

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

Triantafillou, N.D.; Miller, J.T.; Gates, B.C.

Catalysts consisting of Ir clusters in zeolite KLTL were prepared by reduction of [Ir(NH{sub 3}){sub 5}Cl]Cl{sub 2} in the zeolite with H{sub 2} at temperatures 300 or 500{degrees}C. The catalysts were tested for reactions of n-hexane and H{sub 2} at 400, 440 and 480{degrees}C and were characterized by temperature-programmed reduction, hydrogen chemisorption, transmission electron microscopy, infrared spectroscopy of adsorbed CO, and extended X-ray absorption fine structure spectroscopy. The clusters consist of 4 to 6 Ir atoms on average and are sufficiently small to reside within the pores of the zeolite. The infrared spectra characteristic of terminal CO suggest that themore » support environment is slightly basic and that the Ir clusters are electron rich relative to the bulk metal. Notwithstanding the small cluster size, the support basicity, and the confining geometry of the LTL zeolite pore structure, the catalytic performance is similar to those of other Ir catalysts, with a poor selectivity for aromatization and a high selectivity for hydrogenolysis. These results are consistent with the inference that the principal requirements for selective naphtha aromatization catalysts are both a nonacidic support and a metal with a low hydrogenolsis activity, i.e., Pt. 47 refs., 6 figs., 3 tabs.« less

Local structural aspects of metal-metal transition in IrTe2 from x-ray PDF

NASA Astrophysics Data System (ADS)

Yu, Runze; Abeykoon, Milinda; Zhou, Haidong; Yin, Weiguo; Bozin, Emil S.

Evolution of local atomic structure across the metal-metal transition in IrTe2 is explored by pair distribution function (PDF) analysis of x-ray total scattering data over 80 K

A passive infrared ice detection technique for helicopter applications

NASA Technical Reports Server (NTRS)

Dershowitz, Adam L.; Hansman, R. John, Jr.

1991-01-01

A technique has been developed, and successfully tested, to detect icing remotely on helicopter rotor blades. Using passive infrared (IR) thermometry it is possible to detect the warming caused by latent heat released as supercooled water freezes. During icing, the ice accretion region on the leading edge of the blade is found to be warmer than the uniced trailing edge resulting in a chordwise temperature profile characteristic of icing. Preliminary tests, using an IR Thermal video system, were conducted on a static model in the NASA Icing Research Tunnel (IRT) for a variety of wet (glaze) and dry (rime) ice conditions. A prototype detector system was built consisting of a single point IR pyrometer, and experiments were run on a small scale rotor model. Using this prototype detector, the characteristic chordwise temperature profiles were again observed for a range of icing conditions. Several signal processing methods were investigated, to allow automatic recognition of the icing signature. Additionally, several implementation issues were considered. Based on both the static and subscale rotor tests, where ice was successfully detected, the passive IR technique appears to be promising for rotor ice detection.

Size-of-source Effect in Infrared Thermometers with Direct Reading of Temperature

NASA Astrophysics Data System (ADS)

Manoi, A.; Saunders, P.

2017-07-01

The size-of-source effect (SSE) for six infrared (IR) thermometers with direct reading of temperature was measured in this work. The alternative direct method for SSE determination, where the aperture size is fixed and the measurement distance is varied, was used in this study. The experimental equivalence between the usual and the alternative direct methods is presented. The magnitudes of the SSE for different types of IR thermometers were investigated. The maxima of the SSE were found to be up to 5 %, 8 %, and 28 % for focusable, closed-focus, and open-focus thermometers, respectively. At 275°C, an SSE of 28 % corresponds to 52°C, indicating the severe effect on the accuracy of this type of IR thermometer. A method to realize the calibration conditions used by the manufacturer, in terms of aperture size and measurement distance, is discussed and validated by experimental results. This study would be of benefit to users in choosing the best IR thermometer to match their work and for calibration laboratories in selecting the technique most suitable for determining the SSE.

A reliable confirmation of the chemical structure of synthetic oligonucleotides: Detection of active protons in DNA oligomers by low-temperature FT infrared spectroscopy

NASA Astrophysics Data System (ADS)

Rozenberg, M.; Shoham, G.

2009-01-01

Cooling the samples allowed us to characterize solid oligonucleotides such as dimers, trimers and pentamers of cytidine, for the first time, in the IR range of the out-of-plane bending molecular modes (1000-400 cm -1) at 20 K. Especially interesting are the narrow IR bands of the out-of-plane bending ν4 NH 2 proton mode, which are apparently invisible at room temperature. This unequivocally defined and well-resolved NH 2 bending band should provide important information on the exact chemical form and hydrogen bonding interactions of cytidine amine groups. As such, this unique IR spectroscopy is suggested as a practical analytical tool to validate and characterize synthetic DNA bases and oligonucleotides. Using an approach of this type it was found that desalted oligonucleotide samples of the same nominal composition, but which had been produced by three different manufacturers, differ significantly in their IR spectra. These data suggest that the presumably identical oligonucleotides are in fact different, at least with respect to the content and nature of their NH protons.

A reliable confirmation of the chemical structure of synthetic oligonucleotides: detection of active protons in DNA oligomers by low-temperature FT infrared spectroscopy.

PubMed

Rozenberg, M; Shoham, G

2009-01-01

Cooling the samples allowed us to characterize solid oligonucleotides such as dimers, trimers and pentamers of cytidine, for the first time, in the IR range of the out-of-plane bending molecular modes (1000-400 cm(-1)) at 20K. Especially interesting are the narrow IR bands of the out-of-plane bending nu(4) NH(2) proton mode, which are apparently invisible at room temperature. This unequivocally defined and well-resolved NH(2) bending band should provide important information on the exact chemical form and hydrogen bonding interactions of cytidine amine groups. As such, this unique IR spectroscopy is suggested as a practical analytical tool to validate and characterize synthetic DNA bases and oligonucleotides. Using an approach of this type it was found that desalted oligonucleotide samples of the same nominal composition, but which had been produced by three different manufacturers, differ significantly in their IR spectra. These data suggest that the presumably identical oligonucleotides are in fact different, at least with respect to the content and nature of their NH protons.

The thermal background determines how the infrared and visual systems interact in pit vipers.

PubMed

Chen, Qin; Liu, Yang; Brauth, Steven E; Fang, Guangzhan; Tang, Yezhong

2017-09-01

The thermal infrared (IR) sensing system of pit vipers is believed to complement vision and provide a substitute imaging system in dark environments. Theoretically, the IR system would best image a scene consisting of a homothermal target in cold surroundings as a bright spot on a dark background. To test this hypothesis, we evaluated how the pit viper ( Gloydius brevicaudus ) discriminates and strikes prey when the background temperature is either higher or lower than that of the prey (approximately 32-33°C) in different parts of the scene. Snakes were tested in a modified predation cage in which background temperatures were set to 26°C on one side and either 33 or 40°C on the opposite side when the eyes, the pit organs or neither sensory system was occluded. When the eyes were blocked, snakes preferred to strike prey on the 26°C side rather than on the 33°C side but showed no bias in the other conditions. Snakes showed no preference for 26 versus 40°C background temperature, although more missed strikes occurred when the eyes were occluded. The results thus revealed that the pit viper IR system can accomplish a 'brightness constancy' computation reflecting the difference between the target and background temperatures, much as the visual system compares the luminance of a figure and the background. Furthermore, the results show that the IR system performs less well for locating prey when the background is warmer than the target. © 2017. Published by The Company of Biologists Ltd.

Improved high operating temperature MCT MWIR modules

NASA Astrophysics Data System (ADS)

Lutz, H.; Breiter, R.; Figgemeier, H.; Schallenberg, T.; Schirmacher, W.; Wollrab, R.

2014-06-01

High operating temperature (HOT) IR-detectors are a key factor to size, weight and power (SWaP) reduced IR-systems. Such systems are essential to provide infantrymen with low-weight handheld systems with increased battery lifetimes or most compact clip-on weapon sights in combination with high electro-optical performance offered by cooled IR-technology. AIM's MCT standard n-on-p technology with vacancy doping has been optimized over many years resulting in MWIR-detectors with excellent electro-optical performance up to operating temperatures of ~120K. In the last years the effort has been intensified to improve this standard technology by introducing extrinsic doping with Gold as an acceptor. As a consequence the dark current could considerably be suppressed and allows for operation at ~140K with good e/o performance. More detailed investigations showed that limitation for HOT > 140K is explained by consequences from rising dark current rather than from defective pixel level. Recently, several crucial parameters were identified showing great promise for further optimization of HOT-performance. Among those, p-type concentration could successfully be reduced from the mid 1016 / cm3 to the lower 1015/ cm3 range. Since AIM is one of the leading manufacturers of split linear cryocoolers, an increase in operating temperature will directly lead to IR-modules with improved SWaP characteristics by making use of the miniature members of its SX cooler family with single piston and balancer technology. The paper will present recent progress in the development of HOT MWIR-detector arrays at AIM and show electro-optical performance data in comparison to focal plane arrays produced in the standard technology.

Infrared thermography and thermocouple mapping of radiofrequency renal ablation to assess treatment adequacy and ablation margins.

PubMed

Ogan, Kenneth; Roberts, William W; Wilhelm, David M; Bonnell, Leonard; Leiner, Dennis; Lindberg, Guy; Kavoussi, Louis R; Cadeddu, Jeffrey A

2003-07-01

The primary disadvantage of renal tumor RF ablation is the inability to monitor the intraoperative propagation of the RF lesion with real-time imaging. We sought to assess whether adequately lethal temperatures are obtained at the margins of the intended ablation zone using laparoscopic thermography to monitor radiofrequency (RF) lesions in real time, thermocouple measurements, and histopathologic evaluation. Renal RF lesions were created under direct laparoscopic vision in the upper (1 cm diameter) and lower (2 cm) poles of the right kidney in 5 female pigs. The RF lesions were produced with the RITA generator and probe, set at 105 degrees C for 5-minute ablations. During RF treatment, a laparoscopic infrared (IR) camera measured the surface parenchymal temperatures, as did multiple thermocouples. The pigs were then either immediately killed (n = 3) or allowed to live for 2 weeks (n = 2). The kidneys were removed to correlate the temperature measurements with histologic analysis of the ablated lesion. Using a threshold temperature of greater than 70 degrees C for visual "temperature" color change, the IR camera identified the region of pathologic necrosis of the renal parenchyma during RF ablation. Thermocouple measurements demonstrated that the temperatures at the intended ablation radius reached 77.5 degrees C at the renal surface and 83.7 degrees C centrally, and temperatures 5 mm beyond the set radius reached 52.6 degrees C at the surface and 47.7 degrees C centrally. The average diameter of the gross lesion on the surface of the kidney measured 17.1 mm and 22.4 mm for 1-cm and 2-cm ablations, respectively. These surface measurements correlated with an average diameter of 16.1 mm and 15.9 mm (1-cm and 2-cm ablations, respectively) as measured with the IR camera. All cells within these ablation zones were nonviable by nicotinamide adenine dinucleotide diaphorase analysis. The average depth of the lesions measured 19 mm (1-cm ablation) and 25 mm (2-cm ablation) on gross histologic examination. The laparoscopic IR camera is able to monitor the surface renal temperatures during RF treatment. Thermocouple measurements during RF ablation confirmed the thermographic findings and demonstrated that lethal temperatures at the margin of the intended treatment zone are routinely obtained and that a rapid decline in temperature occurs beyond the predicted ablation margin.

Layered structure and related magnetic properties for annealed Fe/Ir(111) ultrathin films

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

Jiang, Pei-Cheng; Chen, Wei-Hsiang; Hsieh, Chen-Yuan

2015-05-07

After annealing treatments for fcc-Fe/Ir(111) below 600 K, the surface layers remain pseudomorphic. The Ir(111) substrate plays an important role on the expanded Fe lattice. At temperatures between 750 and 800 K, the surface composition shows a stable state and a c(2 × 4) structure is observed. We discover a layered structure composed of some Fe atoms on the top of a Fe{sub 0.5}Ir{sub 0.5} interfacial alloy supported on the Ir(111) substrate. The competition between the negative formation heat of Fe{sub 0.5}Ir{sub 0.5} and surface free energy of Fe causes the formation of layered structure. The existence of ferromagnetic dead layer coincides with themore » formation of fcc-Fe for ultrathin Fe on Fe{sub 0.5}Ir{sub 0.5}/Ir(111). For Fe films thicker than three monolayers, the linear increase of the Kerr intensity versus the Fe coverage is related to the growing of bcc-Fe on the surface where the Fe layer is incoherent to the underlying Fe{sub 0.5}Ir{sub 0.5}/Ir(111). These results emphasize the importance of the substrate induced strain and layered structure of Fe/Fe{sub 0.5}Ir{sub 0.5}/Ir(111) on the magnetic properties and provide valuable information for future applications.« less

Total Defense + Repair: A Novel Concept in Solar Protection and Skin Rejuvenation.

PubMed

McDaniel, David H; Hamzavi, Iltefat H; Zeichner, Joshua A; Fabi, Sabrina G; Bucay, Vivian W; Harper, Julie C; Comstock, Jody A; Makino, Elizabeth T; Mehta, Rahul C; Vega, Virginia L

2015-07-01

For more than a century, solar radiation has been known to contribute significantly to the extrinsic aging of skin. Until recently, this was almost exclusively attributed to the photodamage caused by ultraviolet (UV) light. However, a growing body of evidence now indicates that both infrared (IR) and visible light may also contribute to extrinsic skin aging. Infrared radiation, comprised of IR-A, IR-B, and IR-C, accounts for 54.3% of the total solar radiation reaching the skin. Studies have shown that IR radiation is also responsible for skin aging. Thus, IR-A radiation regulates hundreds of genes in skin, with roles in extracellular matrix (ECM) homeostasis regulation, apoptosis, cell growth, and stress responses. IR-B and IR-C radiation are primarily responsible for the increase in skin temperature associated with solar exposure, and are implicated in heat-related skin destruction of collagen and elastin, which is characterized by an increase in the expression of matrix metalloproteinases (MMPs). The contribution of visible light to photoaging is less well understood; however, some preliminary indication associates visible light with the upregulation of MMPs' expression, DNA damage, and keratinocyte proliferation. Interestingly, the common denominator that links skin damage to the different solar wavelengths is the enhanced production of reactive molecule species (RMS) and therewith increased oxidative stress. SkinMedica® Total Defense + Repair (TD+R; SkinMedica Inc., an Allergan company, Irvine, CA) is a "superscreen," which combines broad spectrum UV protection with a unique blend of antioxidants (SOL-IR Advanced Antioxidant Complex™) that provide protection from IR radiation while promoting skin repair. Preclinical studies have indicated that TD+R SPF34 prevents the formation of UV-induced sunburn cells and cyclobutane pyrimidine dimers while preserving or improving the expression of ECM genes. In addition, it prevents IR-A-triggered fragmentation of elastin fibers and expression of MMP-1. Initial clinical studies indicate that TDR+R SPF34 reduces the increase in surface temperature seen with IR radiation. A significant improvement in the appearance of lines and wrinkles was reported as early as week 2 in patients using TDR+R SPF34. In summary, we observed that the unique blend of antioxidants present in TD+R acts in harmony with SPF active ingredients, expanding solar protection beyond UV radiation and counterbalancing the deleterious effects of free radicals on skin cells by promoting endogenous repair.

The automated analysis of clustering behaviour of piglets from thermal images in response to immune challenge by vaccination.

PubMed

Cook, N J; Bench, C J; Liu, T; Chabot, B; Schaefer, A L

2018-01-01

An automated method of estimating the spatial distribution of piglets within a pen was used to assess huddling behaviour under normal conditions and during a febrile response to vaccination. The automated method was compared with a manual assessment of clustering activity. Huddling behaviour was partly related to environmental conditions and clock time such that more huddling occurred during the night and at lower ambient air temperatures. There were no positive relationships between maximum pig temperatures and environmental conditions, suggesting that the narrow range of air temperatures in this study was not a significant factor for pig temperature. Spatial distribution affected radiated pig temperature measurements by IR thermography. Higher temperatures were recorded in groups of animals displaying huddling behaviour. Huddling behaviour was affected by febrile responses to vaccination with increased huddling occurring 3 to 8 h post-vaccination. The automated method of assessing spatial distribution from an IR image successfully identified periods of huddling associated with a febrile response, and to changing environmental temperatures. Infrared imaging could be used to quantify temperature and behaviour from the same images.

Controlling T c of Iridium films using interfacial proximity effects

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

Hennings-Yeomans, R; Chang, CL; Ding, J

High precision calorimetry using superconducting transition edge sensors requires the use of superconducting films with a suitable T c, depending on the application. To advance high-precision macrocalorimetry, we require low-T c films that are easy to fabricate. A simple and effective way to suppress T c of superconducting Iridium through the proximity effect is demonstrated by using Ir/Pt bilayers as well as Au/Ir/Au trilayers. While Ir/Au films fabricated by applying heat to the substrate during Ir deposition have been used in the past for superconducting sensors, we present results of T c suppression on Iridium by deposition at room temperature in Au/Ir/Au trilayers and Ir/Pt bilayers in the range ofmore » $$\\sim$$20-100~mK. Measurements of the relative impedance between the Ir/Pt bilayers and Au/Ir/Au trilayers fabricated show factor of $$\\sim$$10 higher values in the Ir/Pt case. These new films could play a key role in the development of scalable superconducting transition edge sensors that require low-T c films to minimize heat capacity and maximize energy resolution, while keeping high-yield fabrication methods.« less

Directional satellite thermal IR measurements and modeling of a forest in winter and their relationship to air temperature

NASA Astrophysics Data System (ADS)

Balick, Lee K.; Ballard, Jerrell R., Jr.; Smith, James A.; Goltz, Stewart M.

2002-01-01

Data assimilation methods applied to hydrologic models can incorporate spatially distributed maps of near surface temperature, especially if such measurements can be reliably inferred from satellite observations. Uncalibrated thermal IR imagery sometimes is scaled to temperature units to obtain such observations using the assumption that dense forest canopies are close to air temperature. For fully leafed deciduous forest canopies in the summer, this approximation is usually valid within 2C. In a leafless canopy, however, the materials views are thick boles and branches and the forest floor, which can store heat and yield significantly higher variations. Winter coniferous forests are intermediate with needles and branches being the predominant viewed materials. The US Dept of Energy's Multispectral Thermal Imager (MTI) is an experimental satellite with the capability to perform quantitative scene measurements in the reflective and thermal infrared region respectively. Its multispectral thermal IR capability enables quantitative surface temperature retrieval if pixel emissivity is known. MTI is pointable and targets multiple times in the winter and spring of 2001 at the Howland, Maine AmeriFlux research site operated by the University of Maine. Supporting meteorological and optical depth measurements also were made from three towers at the site. Directional thermal models of forest woody materials and needles are driver by the surface measurements and compared to satellite data to help evaluate the relationship between air temperature and satellite thermal measurements as a function of look angles, day and night.

The MEDA's Radiometer TIRS for the MARS2020 Mission

NASA Astrophysics Data System (ADS)

Pérez Izquierdo, Joel; Sebastián Martínez, Eduardo; Bravo, Andrés; Ferrándiz, Ricardo; Ramos, Miguel; Martínez, Germán; Rodríguez Manfredi, Jose Antonio

2016-10-01

The TIRS (Thermal InfraRed Sensor) instrument is one of the payloads of NASA MARS2020 mission, that is expected to take off in 2020, and is designed to operate for at least three Martian years on surface. The TIRS is part of the Mars Environmental Dynamics Analyzer (MEDA), formed for other environmental sensors, which will be placed in the MARS2020 Rover, and is been developing by the Spanish Center of Astrobiology (CAB).The main objectives of MEDA's Thermal InfraRed Sensor are:-Characterize the net radiative forcing (within 10%), and constrain the conductive forcing at the local surface and near-surface atmosphere.-Record the surface skin temperature and the UV-VIS-NIR irradiance solar flux at an accuracy of [10%] at full range of the atmosphere.TIRS design has heritage from GTS-REMS on the Mars Science Laboratory, in the Curiosity Rover. The aim of the instrument is to measure the radiative flux emitted from the Martian surface, sky and the CO2 atmosphere using five thermopiles sensors in four wavelength bands, model TS100 provided by IPHT (Institute of Photonic Technology, Jena, Germany). The TIRS has three downward pointing thermopiles to measure the IR fluxes emitted by the surface, separating brightness surface temperature from emissivity and surface reflected upward short wave radiation, using the thermopiles IR3 (0.3-3 µm), IR4 (6.5-inf µm), IR5 (8-14 µm). Additionally, it has two more thermopiles pointing to the sky, the thermopiles IR1 (6.5-inf µm) and IR2 (14.5-15.5 µm), which captures the downward fluxes of thermal infrared radiation and air temperature nearby the sensor.Thermopiles are accommodated inside a mechanical assembly that is designed to ensure a low thermal gradient. This assembly also accommodates a calibration plate, aimed to intercept part of the thermopiles FOV, and capable to do an in-flight recalibration.

Relationship between dynamic infrared thermal images and blood perfusion rate of the tongue in anaemia patients

NASA Astrophysics Data System (ADS)

Xie, Haiwei; Zhang, Yan

2018-03-01

The relationship between dynamic infrared (IR) thermal images and blood perfusion rate of the tongues of anaemia patients was investigated. Blood perfusion rates at multiple locations on the tongues of 62 anaemia patients and 70 control subjects were measured. For both groups of subjects, dynamic IR thermal images were also recorded within 16 s after the mouth opened. The results showed that the blood perfusion rates at different sites (apex, middle, left side and right side) on the tongues in anaemia patients (3.49, 3.71, 3.85 and 3.77 kg/s m-3) were significantly lower than those at the corresponding sites in control subjects (4.45, 4.66, 4.81 and 4.70 kg/s m-3). After the mouth opened, the tongue temperature decreased more rapidly in anaemia patients than in control subjects. To analyse the heat transfer mechanism, a transient heat transfer model of the tongue was developed. The tongue temperatures in anaemia patients and control subjects were calculated using this model and compared to the tongue temperatures measured by the IR thermal imager. The relationship between the tongue surface temperature and the tongue blood perfusion rate was analysed. The simulation results indicated that the low blood perfusion rate and the correlated changes in anaemia patients can cause faster temperature decreases of the tongue surface.

The infrared counterpart of GX 13 + 1

NASA Technical Reports Server (NTRS)

Garcia, M. R.; Grindlay, J. E.; Bailyn, C. D.; Pipher, J. L.; Shure, M. A.; Woodward, C. E.

1992-01-01

A bright (K = 12) IR source is discovered which is likely the counterpart to the bright galactic-bulge X-ray source GX 13 + 1. Observations with the MMT IR photometer and the Rochester IR Array camera at the IRTF allow determination of the source position to about 0.7 arcsec, allow the IR colors to be measured, and show no variability on a 1-yr timescale. Four possible sources for the IR emission are considered and it is most likely due to a K-giant secondary. The discovery of a late-type giant secondary in GX 13 + 1 is contrary to the expectation that low-mass X-ray binaries which show quasi-periodic oscillations (QPO) have giant companions, while those which do not show QPO (like GX 13 + 1) have dwarf secondaries. The relation between the size of the scattered X-ray halo and the Av inferred from the IR observations is compared to that found in other X-ray sources.

Structure and properties of α-NaFeO{sub 2}-type ternary sodium iridates

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

Baroudi, Kristen, E-mail: kbaroudi@princeton.edu; Yim, Cindi; Wu, Hui

2014-02-15

The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na{sub 3−x}MIr{sub 2}O{sub 6} and Na{sub 3−x}M{sub 2}IrO{sub 6}, where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn). The rhombohedral structures, in space group R−3m, were determined by refinement of neutron and synchrotron powder diffraction data. No clear evidence for long range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder diffraction patterns except in the case of M=Zn, and thus in general the compounds are best designated as sodium deficient α-NaFeO{submore » 2}-type phases with formulas Na{sub 1−x}M{sub 1/3}Ir{sub 2/3}O{sub 2} or Na{sub 1−x}M{sub 2/3}Ir{sub 1/3}O{sub 2}. Synchrotron powder diffraction patterns indicate that several of the compounds likely have honeycomb in-plane metal–iridium ordering with disordered stacking of the layers. All the compounds are sodium deficient under our synthetic conditions and are black and insulating. Weiss constants derived from magnetic susceptibility measurements indicate that Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2}, and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} display dominant antiferromagnetic interactions. For Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2} the dominant magnetic interactions at low temperature are ferromagnetic while at high temperatures they are antiferromagnetic; there is also a change in the effective moment. Low temperature specific heat measurements (to 2 K) on Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2} indicate the presence of a broad magnetic ordering transition. X-ray absorption spectroscopy shows that iridium is at or close to the 4+ oxidation state in all compounds. {sup 23}Na nuclear magnetic resonance measurements comparing Na{sub 2}IrO{sub 3} to Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} provide strong indications that the electron spins are short-range ordered in the latter two materials. Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}, Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} are spin glasses. (CSD-numbers: Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}: 426657, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}: 426659, Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2}: 426658, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}: 426656, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2}: 426655, and Na{sub 2.8}ZnIr{sub 2}O{sub 6}: 426660.) - Graphical abstract: Diffraction patterns of Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2}: neutron diffraction patterns in the main panel and synchrotron diffraction in the insets. The patterns show a small amount of ordering in the transition metal iridium layer. Display Omitted - Highlights: • We report six ternary sodium iridates with the α-NaFeO{sub 2} structure. • Compounds Na{sub 1−x}M{sub 1/3}Ir{sub 2/3}O{sub 2}, M=Co, Ni, Cu, Zn and Na{sub 1−x}M{sub 2/3}Ir{sub 1/3}O{sub 2}, M=Mn, Fe. • Rietveld refinement of powder neutron diffraction data. • All compounds are spin glasses. • NMR comparison to Na{sub 2}IrO{sub 3}.« less

A MODEL FOR (QUASI-)PERIODIC MULTIWAVELENGTH PHOTOMETRIC VARIABILITY IN YOUNG STELLAR OBJECTS

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

Kesseli, Aurora Y.; Petkova, Maya A.; Wood, Kenneth

We present radiation transfer models of rotating young stellar objects (YSOs) with hot spots in their atmospheres, inner disk warps, and other three-dimensional effects in the nearby circumstellar environment. Our models are based on the geometry expected from magneto-accretion theory, where material moving inward in the disk flows along magnetic field lines to the star and creates stellar hot spots upon impact. Due to rotation of the star and magnetosphere, the disk is variably illuminated. We compare our model light curves to data from the Spitzer YSOVAR project to determine if these processes can explain the variability observed at opticalmore » and mid-infrared wavelengths in young stars. We focus on those variables exhibiting “dipper” behavior that may be periodic, quasi-periodic, or aperiodic. We find that the stellar hot-spot size and temperature affects the optical and near-infrared light curves, while the shape and vertical extent of the inner disk warp affects the mid-IR light curve variations. Clumpy disk distributions with non-uniform fractal density structure produce more stochastic light curves. We conclude that magneto-accretion theory is consistent with certain aspects of the multiwavelength photometric variability exhibited by low-mass YSOs. More detailed modeling of individual sources can be used to better determine the stellar hot-spot and inner disk geometries of particular sources.« less

Epitaxial growth of Al9Ir2 intermetallic compound on Al(100): Mechanism and interface structure

NASA Astrophysics Data System (ADS)

Kadok, J.; Pussi, K.; Šturm, S.; Ambrožič, B.; Gaudry, É.; de Weerd, M.-C.; Fournée, V.; Ledieu, J.

2018-04-01

The adsorption of Ir adatoms on Al(100) has been investigated under various exposures and temperature conditions. The experimental and theoretical results reveal a diffusion of Ir adatoms within the Al(100) surface selvedge already at 300 K. Above 593 K, two domains of a (√{5 }×√{5 }) R 26 .6∘ phase are identified by low energy electron diffraction (LEED) and scanning tunneling microscopy measurements. This phase corresponds to the initial growth of an Al9Ir2 compound at the Al(100) surface. The Al9Ir2 intermetallic domains are terminated by bulklike pure Al layers. The structural stability of Al9Ir2 (001) grown on Al(100) has been analyzed by density functional theory based calculations. Dynamical LEED analysis is consistent with an Ir adsorption leading to the growth of an Al9Ir2 intermetallic compound. We propose that the epitaxial relationship Al9Ir2(001 ) ∥Al (100) and Al9Ir2[100 ] ∥Al [031 ]/[013 ] originates from a matching of Al atomic arrangements present both on Al(100) and on pure Al(001) layers present in the Al9Ir2 compound. Finally, the interface between Al9Ir2 precipitates and the Al matrix has been characterized by transmission electron microscopy measurements. The cross-sectional observations are consistent with the formation of Al9Ir2 (001) compounds. These measurements indicate an important Ir diffusion within Al(100) near the surface region. The coherent interface between Al9Ir2 and the Al matrix is sharp.

SPITZER IRAC OBSERVATIONS OF IR EXCESS IN HOLMBERG IX X-1: A CIRCUMBINARY DISK OR A VARIABLE JET?

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

Dudik, R. P.; Berghea, C. T.; Roberts, T. P.

2016-11-01

We present Spitzer Infrared Array Camera photometric observations of the ultraluminous X-ray source (ULX, X-1) in Holmberg IX. We construct a spectral energy distribution (SED) for Holmberg IX X-1 based on published optical, UV, and X-ray data combined with the IR data from this analysis. We modeled the X-ray and optical data with disk and stellar models; however, we find a clear IR excess in the ULX SED that cannot be explained by fits or extrapolations of any of these models. Instead, further analysis suggests that the IR excess results from dust emission, possibly a circumbinary disk, or a variablemore » jet.« less

Modelling Epsilon Aurigae without solid particles

NASA Technical Reports Server (NTRS)

Cheng, A. Y. S.; Woolf, N. J.

1985-01-01

Three components can be expected to contribute to the emission of epsilon Aurigae. There is a primary F star. There is an opaque disk which occults it, and there is a gas stream which is observed to produce absorption lines. Evidence that the disk is not responsible for the gas stream lines comes both from the radial velocities, which are too small, and from the IR energy distribution out of eclipse, which shows free-free emission that would produce inadequate optical depth in electron scattering. The color temperature of the IR excess can give misleading indications of low temperature material. Free-free emission at 10,000 K between 10 and 20 microns has a color temperature of 350 K. Attempts to mold the system are discussed.

Artifact Correction in Temperature-Dependent Attenuated Total Reflection Infrared (ATR-IR) Spectra.

PubMed

Sobieski, Brian; Chase, Bruce; Noda, Isao; Rabolt, John

2017-08-01

A spectral processing method was developed and tested for analyzing temperature-dependent attenuated total reflection infrared (ATR-IR) spectra of aliphatic polyesters. Spectra of a bio-based, biodegradable polymer, 3.9 mol% 3HHx poly[(R)-3-hydroxybutyrate- co-(R)-3-hydroxyhexanoate] (PHBHx), were analyzed and corrected prior to analysis using two-dimensional correlation spectroscopy (2D-COS). Removal of the temperature variation of diamond absorbance, correction of the baseline, ATR correction, and appropriate normalization were key to generating more reliable data. Both the processing steps and order were important. A comparison to differential scanning calorimetry (DSC) analysis indicated that the normalization method should be chosen with caution to avoid unintentional trends and distortions of the crystalline sensitive bands.

Birth-weight, insulin levels, and HOMA-IR in newborns at term.

PubMed

Simental-Mendía, Luis E; Castañeda-Chacón, Argelia; Rodríguez-Morán, Martha; Guerrero-Romero, Fernando

2012-07-07

Recent studies have demonstrated that low and high birth-weight at birth are risk factors of developing diabetes. The aim of this study was to determine if the abnormal birth-weight is related with hyperinsulinemia and elevated index of the Homeostasis Model assessment for Insulin Resistance (HOMA-IR) at birth, in at term newborns. Newborns with gestational age between 38 and 41 weeks, products of normal pregnancies of healthy mothers aged 18 to 39 years, were eligible to participate. Small-for-gestational age (SGA) and large-for-gestational age (LGA) newborns were compared with appropriate-for-gestational (AGA) age newborns. Incomplete or unclear data about mother's health status, diabetes, gestational diabetes, history of gestational diabetes, hypertension, pre-eclampsia, eclampsia, and other conditions that affect glucose metabolism were exclusion criteria. Hyperinsulinemia was defined by serum insulin levels ≥13.0 μU/mL and IR by HOMA-IR ≥2.60. Multiple logistic regression analysis was used to determine the odds ratio (OR) that computes the association between birth-weight (independent variable) with hyperinsulinemia and HOMA-IR index (dependent variables). A total of 107 newborns were enrolled; 13, 22, and 72 with SGA, LGA, and AGA, respectively. Hyperinsulinemia was identified in 2 (15.4%), 6 (27.3%), and 5 (6.9%) with SGA, LGA, and AGA (p=0.03), whereas IR in 3 (23.1%), 8 (36.4%), and 10 (13.9%) newborns with SGA, LGA and AGA (p=0.06). The LGA showed a strong association with hyperinsulinemia (OR 5.02; CI 95%, 1.15-22.3; p=0.01) and HOMA-IR (OR 3.54; CI 95%, 1.03-12.16; p=0.02); although without statistical significance, the SGA showed a tendency of association with hyperinsulinemia (OR 2.43; CI 95%, 0.43-17.3 p=0.29) and HOMA-IR (OR 1.86; CI 95%, 0.33-9.37; p=0.41). Our results suggest that LGA is associated with hyperinsulinemia and elevated HOMA-IR at birth whereas the SGA show a tendency of association.

Highly Efficient Red and White Organic Light-Emitting Diodes with External Quantum Efficiency beyond 20% by Employing Pyridylimidazole-Based Metallophosphors.

PubMed

Miao, Yanqin; Tao, Peng; Wang, Kexiang; Li, Hongxin; Zhao, Bo; Gao, Long; Wang, Hua; Xu, Bingshe; Zhao, Qiang

2017-11-01

Two highly efficient red neutral iridium(III) complexes, Ir1 and Ir2, were rationally designed and synthesized by selecting two pyridylimidazole derivatives as the ancillary ligands. Both Ir1 and Ir2 show nearly the same photoluminescence emission with the maximum peak at 595 nm (shoulder band at about 638 nm) and achieve high solution quantum yields of up to 0.47 for Ir1 and 0.57 for Ir2. Employing Ir1 and Ir2 as emitters, the fabricated red organic light-emitting diodes (OLEDs) show outstanding performance with the maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 20.98%, 33.04 cd/A, and 33.08 lm/W for the Ir1-based device and 22.15%, 36.89 cd/A, and 35.85 lm/W for the Ir2-based device, respectively. Furthermore, using Ir2 as red emitter, a trichromatic hybrid white OLED, showing good warm white emission with low correlated color temperature of <2200 K under the voltage of 4-6 V, was fabricated successfully. The white device also realizes excellent device efficiencies with the maximum EQE, CE, and PE reaching 22.74%, 44.77 cd/A, and 46.89 lm/W, respectively. Such high electroluminescence performance for red and white OLEDs indicates that Ir1 and Ir2 as efficient red phosphors have great potential for future OLED displays and lightings applications.

Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings.

PubMed

Khandelwal, Hitesh; Loonen, Roel C G M; Hensen, Jan L M; Debije, Michael G; Schenning, Albertus P H J

2015-07-01

Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector. We have also fabricated a switchable IR reflector which can also generate electricity. These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy.

Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings

PubMed Central

Khandelwal, Hitesh; Loonen, Roel C. G. M.; Hensen, Jan L. M.; Debije, Michael G.; Schenning, Albertus P. H. J.

2015-01-01

Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector. We have also fabricated a switchable IR reflector which can also generate electricity. These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy. PMID:26132328

Improvements in AVHRR Daytime Cloud Detection Over the ARM NSA Site

NASA Technical Reports Server (NTRS)

Chakrapani, V.; Spangenberg, D. A.; Doelling, D. R.; Minnis, P.; Trepte, Q. Z.; Arduini, R. F.

2001-01-01

Clouds play an important role in the radiation budget over Arctic and Antarctic. Because of limited surface observing capabilities, it is necessary to detect clouds over large areas using satellite imagery. At low and mid-latitudes, satellite-observed visible (VIS; 0.65 micrometers) and infrared (IR; 11 micrometers) radiance data are used to derive cloud fraction, temperature, and optical depth. However, the extreme variability in the VIS surface albedo makes the detection of clouds from satellite a difficult process in polar regions. The IR data often show that the surface is nearly the same temperature or even colder than clouds, further complicating cloud detection. Also, the boundary layer can have large areas of haze, thin fog, or diamond dust that are not seen in standard satellite imagery. Other spectral radiances measured by satellite imagers provide additional information that can be used to more accurately discriminate clouds from snow and ice. Most techniques currently use a fixed reflectance or temperature threshold to decide between clouds and clear snow. Using a subjective approach, Minnis et al. (2001) found that the clear snow radiance signatures vary as a function of viewing and illumination conditions as well as snow condition. To routinely process satellite imagery over polar regions with an automated algorithm, it is necessary to account for this angular variability and the change in the background reflectance as snow melts, vegetation grows over land, and melt ponds form on pack ice. This paper documents the initial satellite-based cloud product over the Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) site at Barrow for use by the modeling community. Cloud amount and height are determined subjectively using an adaptation of the methodology of Minnis et al. (2001) and the radiation fields arc determined following the methods of Doelling et al. (2001) as applied to data taken during the Surface Heat and Energy Budget of the Arctic (SHEBA). The procedures and data produced in this empirically based analysis will also facilitate the development of the automated algorithm for future processing of satellite data over the ARM NSA domain. Results are presented for May, June, and July 1998. ARM surface data are use to partially validate the results taken directly over the ARM site.

CO2 and SO2 IR Line Lists for Venus/Mars and Exo-Planet Atmosphere Studies

NASA Astrophysics Data System (ADS)

Huang, X.; Schwenke, D.; Sergey, T. A.; Lee, T. J.

2012-12-01

Atmospheric studies of both solar system planets and extra-solar planets need accurate spectra data input and analysis from planetary missions and astronomical observations. Accurate Infra-Red (IR) line lists of critical species are necessary to determine the physical conditions and compositions of atmospheres. Here we demonstrate an example of how theoretical chemistry can help in this regard. By combining the state-of-the-art ab initio theory, quantum exact rovibrational CI approach, and selected reliable high resolution experimental data, we have successfully generated the most complete and reliable IR line lists for Carbon Dioxide and Sulfur Dioxide (and their isotopologues) with accuracies of 0.01-0.02 cm-1, or ~10 MHz for microwave spectra. Agreement for observed intensities is around 90%. Our approach not only automatically fills in all the missing bands (especially those weaker, difficult bands) below the highest experiment energies, but also safely extrapolates beyond those with still reliable predictions. The reliability and accuracy of our IR line lists have been verified by the most recent experiments. The CO2 line list actually extends to 30,000 cm-1 and J>180. It works for early planets with temperature as high as 1000-2000K. The SO2 line list covers 0 - 14000 cm-1 and J>100. These line lists are expected to facilitate the atmospheric analysis and modeling of both planets (and moons) within our solar system and beyond to extra-solar planets. 32SO2 IR spectra comparison. (top) Ames-296K line list vs. recent experiment; (bottom) Ames-296K fills in the gaps of HITRAN2008 data. 12C16O2 IR Simulation at different temperatures using the latest Ames-296K IR linelist. (Unpublished work by R.S. Freedman, SETI/NASA Ames SST)

Pulsed Infrared Releases Ca2+ from the Endoplasmic Reticulum of Cultured Spiral Ganglion Neurons.

PubMed

Barrett, John N; Rincon, Samantha; Singh, Jayanti; Matthewman, Cristina; Pasos, Julio; Barrett, Ellen F; Rajguru, Suhrud M

2018-04-18

We investigated the effects of pulsed infrared radiation (IR, 1863 nm) stimulation on cytosolic [Ca 2+ ] in inner ear spiral ganglion neurons cultured from day 4 postnatal mice and loaded with a fluorescent Ca 2+ indicator (fluo-4, -5F or -5N). IR pulse trains (200 µs, 200-250 Hz, 2-5 s) delivered via an optical fiber coupled to IR source produced a rapid, transient temperature increase of 6-11ºC (above a baseline of 24-30 ºC) and evoked transient increases in both nuclear and cytosolic [Ca 2+ ] of 0.20 - 1.4 µM, with a simultaneous reduction of [Ca 2+ ] in regions containing endoplasmic reticulum (ER). IR-induced increases in cytosolic [Ca 2+ ] continued in medium containing no added Ca 2+ ({plus minus} Ca 2+ buffers) and low [Na + ], indicating that the [Ca 2+ ] increase was mediated by release from intracellular stores. Consistent with this hypothesis, the IR-induced [Ca 2+ ] response was prolonged and eventually blocked by inhibition of ER Ca-ATPase with cyclopiazonic acid, and was also inhibited by a high concentration of ryanodine and by inhibitors of IP 3 -mediated Ca 2+ release (xestospongin C and 2-APB). The thermal sensitivity of the response suggested involvement of warm-sensitive transient receptor potential (TRP) receptors. Immunostaining of the spiral ganglion demonstrated the presence of intracellular TRPV4 and TRPM2, and the IR-induced [Ca 2+ ] increase was inhibited by TRPV4 inhibitors (HC067047 and GSK2193874). These results suggest that the temperature-sensitivity of IR-induced [Ca 2+ ] elevations is conferred by TRP channels on ER membranes, which facilitate Ca 2+ efflux into the cytosol and initiate Ca 2+ -induced Ca 2+ -release via IP 3 and ryanodine receptors.

Infrared imaging technology and biological applications.

PubMed

Kastberger, Gerald; Stachl, Reinhold

2003-08-01

Temperature is the most frequently measured physical quantity, second only to time. Infrared (IR) technology has been utilized successfully in astronomy (for a summary,see Hermans-Killam, 2002b) and in industrial and research settings (Gruner, 2002; Madding, 1982, 1989; Wolfe & Zissis, 1993) for decades. However, fairly recent innovations have reduced costs, increased reliability, and resulted in noncontact IR sensors offering mobile, smaller units of measurement (EOI, 2002; Flir, 2000, 2001,2002). The advantages of using IR imaging are (1) rapidity in the millisecond range, facilitating measurement of moving targets, (2) noncontact procedures, allowing measurements of hazardous or physically inaccessible objects, (3) no interference and no energy lost from the target, (4) no risk of contamination, and (5) no mechanical effect on the surface of the object. All these factors have led to IR technology's becoming an area of interest for new kinds of applications and users. In both manufacturing and quality control, temperature plays an important role as an indicator of the condition of a product or a piece of machinery (EOI, 2002; Flir, 2000, 2001, 2002; Raytek, 2002). In medical and veterinary applications, IR thermometry is increasingly used in organ diagnostics, in the evaluation of sports injuries and the progression of therapy, in disease evaluation (e.g, breast cancer, arthritis, and SARS; Flir, 2003), and in injury and inflammation examinations in horses, livestock (Tivey & Banhazi, 2002), and zoo animals (Hermans-Killam, 2002a; Thiesbrummel, 2002). Lastly, physiological expressions of life processes in animals (Kastberger, Winder, & Steindl, 2001; Stabentheiner, Kovac, & Hagmüller, 1995; Stabentheiner, Kovac, & Schmaranzer, 2002; Stabentheiner & Schmarnzer, 1987) and plants (Bermadinger-Stabentheiner & Stabentheiner, 1995) can be monitored. The most recent field in which IR technology has been applied is animal behavior. This article focuses on the practical options for noncontact IR thermometry--in particular, in biological applications.

Exchange bias of Ni nanoparticles embedded in an antiferromagnetic IrMn matrix.

PubMed

Kuerbanjiang, Balati; Wiedwald, Ulf; Haering, Felix; Biskupek, Johannes; Kaiser, Ute; Ziemann, Paul; Herr, Ulrich

2013-11-15

The magnetic properties of Ni nanoparticles (Ni-NPs) embedded in an antiferromagnetic IrMn matrix were investigated. The Ni-NPs of 8.4 nm mean diameter were synthesized by inert gas aggregation. In a second processing step, the Ni-NPs were in situ embedded in IrMn films or SiOx films under ultrahigh vacuum (UHV) conditions. Findings showed that Ni-NPs embedded in IrMn have an exchange bias field HEB = 821 Oe at 10 K, and 50 Oe at 300 K. The extracted value of the exchange energy density is 0.06 mJ m(-2) at 10 K, which is in good accordance with the results from multilayered thin film systems. The Ni-NPs embedded in SiOx did not show exchange bias. As expected for this particle size, they are superparamagnetic at T = 300 K. A direct comparison of the Ni-NPs embedded in IrMn or SiOx reveals an increase of the blocking temperature from 210 K to around 400 K. The coercivity of the Ni-NPs exchange coupled to the IrMn matrix at 10 K is 8 times larger than the value for Ni-NPs embedded in SiOx. We studied time-dependent remanent magnetization at different temperatures. The relaxation behavior is described by a magnetic viscosity model which reflects a rather flat distribution of energy barriers. Furthermore, we investigated the effects of different field cooling processes on the magnetic properties of the embedded Ni-NPs. Exchange bias values fit to model calculations which correlate the contribution of the antiferromagnetic IrMn matrix to its grain size.

Characterizing spatial and temporal patterns of intermittent rivers

NASA Astrophysics Data System (ADS)

de Vries, Stefan B.; Hoeve, Jasper; Sauquet, Eric; Leigh, Catherine; Bonada, Núria; Fike, Kimberly; Dahm, Clifford; Booij, Martijn J.; Datry, Thibault

2015-04-01

Intermittent rivers (IRs) support high biodiversity due to their dynamic alternations between terrestrial and aquatic phases. They represent a large proportion of the river network. However the current knowledge on these ecosystems is limited. The international research project "Intermittent River Biodiversity Analysis and Synthesis" (IRBAS, www.irbas.fr) aims to collect and analyze data on IR biodiversity from France, Spain, North America and Australia. These activities ultimately should help in identifying relationships between flow regime components and ecological responses. The IRBAS project will provide guidelines for policy-makers and resource managers for effective water and habitat management, restoration and preservation. This work examines one of the aspects in the IRBAS project: studying the large-scale spatial distribution of IRs as well as the year-to-year variability of zero-flow events. IRs were described by two variables: the frequency of periods without flow (FREQ) per time period (months or years) and the total number of zero-flow days (DUR) in a specified time window (month or year). Daily discharge data from more than 1700 gauging stations with no significant human influence on flow were collected from France, Spain, Australia and conterminous United States. A minimum length of 30 years of data starting from 1970 was required with less than 5% of missing data. Climate data for France and Australia were also collected. A classification of perennial versus intermittent rivers was defined, with 455 stations out of the 1684 considered "intermittent", i.e. the gauging station records had, on average, at least 5 zero-flow days per year. The analysis of the subset of IRs showed that: - Greater than 50% of the IRs in the database is located in Australia, where only 35% of the stations are considered perennial. In Spain the proportion of IRs reaches 25%. The proportion of intermittent rivers in France (7%) is certainly underestimated as a consequence of the monitoring strategy, i.e. gauging stations have been primarily installed to measure perennial flows of medium size basins and most of the IRs remain ungauged. This is also true in the US where ~ 7% of the current and historical gage network is on intermittent rivers. - Intermittence of rivers demonstrates high seasonality which varies from one country to another. - Links between climate variability and intermittence are not straightforward. No relation was found between annual DUR and annual precipitation in France whereas DUR was significantly correlated with precipitation in Australia. Potential evapotranspiration was correlated with DUR for France, but not for Australia, where the results were more obscure. - No spatially coherent trends in flow intermittence were identified in Spain, France or the USA. Significant trends according to the Mann Kendall test were found in Australia and results suggest trends in yearly DUR consistent with observed changes in rainfall in Western Australia during the last few decades. The El Nino cycle is one of the possible sources of variability in intermittency patterns.

Fibre laser based on tellurium-doped active fibre

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

Alyshev, S V; Ryumkin, K E; Shubin, A V

2014-02-28

We have studied the lasing properties of tellurium-doped germanosilicate fibre, identified its gain and excited-state absorption bands, and assessed the effect of cooling to low temperature (77 K) on the bands. The excitation spectrum of the near-IR luminescence in the fibre has been measured. Lasing at 1.55 mm has been demonstrated for the first time in this gain medium at liquidnitrogen temperature and pump wavelengths of 1.064 and 1.085 mm. The measured Raman spectrum of the fibre provides some insight into the structure of the near-IR luminescence centre. (letters)

Helium broadened propane absorption cross sections in the far-IR

NASA Astrophysics Data System (ADS)

Wong, A.; Billinghurst, B.; Bernath, P. F.

2017-09-01

Infrared absorption spectra for pure and He broadened propane have been recorded in the far-IR region (650-1300 cm-1) at the Canadian Light Source (CLS) facility using either the synchrotron or internal glowbar source depending on the required resolution. The measurements were made for 4 temperatures in the range 202-292 K and for 3 pressures of He broadening gas up to 100 Torr. Infrared absorption cross sections are derived from the spectra and the integrated cross sections are within 10 % of the corresponding values from the Pacific Northwest National Laboratory (PNNL) for all temperatures and pressures.

Enhancement of Fe diffusion in ZnSe/S laser crystals under hot isostatic pressing

NASA Astrophysics Data System (ADS)

Gafarov, Ozarfar; Martinez, Alan; Fedorov, Vladimir; Mirov, Sergey

2017-02-01

Many organic molecules have strong and narrow absorption features in the middle Infrared (mid-IR) spectral range. The ability to directly probe absorption features of molecules enables numerous mid-IR applications in non-invasive medical diagnosis, industrial processing and process control, environmental monitoring, etc. Thus, there is a strong demand for lasers operating in mid-IR spectral range. Transition metal (TM) doped II-VI semiconductors such as Fe/Cr:ZnSe/S are the material of choice for fabrication of mid-IR gain media due to favorable combination of properties: a four level energy structure, absence of excited state absorption , broad mid-IR vibronic absorption and emission bands. Despite the significant progress in post-growth thermal diffusion technology of TM:II-VI fabrication there are still some difficulties associated with diffusion of certain TM's in these materials. In this work we address the issue of poor diffusion of Fe in ZnSe/S polycrystals. It is well known that with the temperature increase the diffusion rate of impurity also increases. However, simple application of high temperatures during the diffusion process is problematic for ZnSe/S crystals due to their strong sublimation. The sublimation processes can be suppressed by application of high pressures. Hot isostatic pressing was utilized as the means for simultaneous application of high temperatures (1300°C) and high pressures (1000atm, 3000atm). It was determined that diffusion coefficient of Fe was improved 13 and 14 fold in ZnSe and ZnS, respectively, as compared to the standard diffusion at 950°C. The difference in diffusion coefficients can be due to strong increase in the grain size of polycrystals.

Application of Fourier transform infrared (FT-IR) spectroscopy to the study of the modification of epoxidized sunflower oil by acrylation.

PubMed

Irinislimane, Ratiba; Belhaneche-Bensemra, Naima

2012-12-01

Commercial sunflower oil was epoxidized at the laboratory-scale. The epoxidized sunflower oil (ESFO) was modified following the acrylation reaction. Modification was carried out simultaneously using acrylic acid (AA) and triethylamine (TEA). To optimize the reaction conditions, the effects of four temperatures (40, 60, 80, and 100 °C), the ESFO:AA (100:100) ratio, and 0.2% TEA were investigated. The rate of conversion was analyzed with both FT-IR and titration of the oxirane ring. After that, the temperature with the highest conversion was selected and used throughout for all modification reactions. Then, four ratios (100:100, 100:90, 100:80, and 100:75) of ESFO:AA were analyzed at four different concentrations of TEA (0.2, 0.3, 0.4, and 0.5%) to determine the best estimate for both the ESFO:AA ratio and the catalyst concentration. Conversion rate was analyzed using FT-IR spectroscopy by measuring the concentrations of ester, carbonyl, and alcohol groups. Moreover, oxirane-ring concentration was estimated using the titration method (with gentian violet as indicator) and FT-IR spectroscopy (epoxy ring absorptions at 1270 cm(-1) and 877 cm(-1)). Based on conversion yield, the optimum ESFO:AA ratio corresponds to 100:80; the best temperature reaction was at 60 °C, and the best TEA concentration was 0.2%. The critical amounts of reactants needed to reach maximum conversion were established. The final acid value of the acrylated ESFO after washing (pH = 7) was 2.1 mg potassium hydroxide (KOH)·g(-1). All results show that FT-IR spectroscopy is a simple, low-cost, rapid method for investigating the kinetics of a reaction.

Exchange field effect in the crystal-field ground state of Ce M Al 4 Si 2

DOE PAGES

Chen, K.; Strigari, F.; Sundermann, M.; ...

2016-09-06

The crystal-field ground-state wave functions of the tetragonal, magnetically ordering Kondo lattice materials CeMAl 4Si 2 (M = Rh, Ir, and Pt) are determined in this paper with low-temperature linearly polarized soft-x-ray absorption spectroscopy, and estimates for the crystal-field splittings are given from the temperature evolution of the linear dichroism. Values for the dominant exchange field in the magnetically ordered phases can be obtained from fitting the influence of magnetic order on the linear dichroism. The direction of the required exchange field is || c for the antiferromagnetic Rh and Ir compounds, with the corresponding strength of the order ofmore » λ ex ≈ 6 meV (65 K). Finally and furthermore, the presence of Kondo screening in the Rh and Ir compound is demonstrated on the basis of the absorption due to f 0 in the initial state.« less

Reliability of infrared thermometric measurements of skin temperature in the hand.

PubMed

Packham, Tara L; Fok, Diana; Frederiksen, Karen; Thabane, Lehana; Buckley, Norman

2012-01-01

Clinical measurement study. Skin temperature asymmetries (STAs) are used in the diagnosis of complex regional pain syndrome (CRPS), but little evidence exists for reliability of the equipment and methods. This study examined the reliability of an inexpensive infrared (IR) thermometer and measurement points in the hand for the study of STA. ST was measured three times at five points on both hands with an IR thermometer by two raters in 20 volunteers (12 normals and 8 CRPS). ST measurement results using IR thermometers support inter-rater reliability: intraclass correlation coefficient (ICC) estimate for single measures 0.80; all ST measurement points were also highly reliable (ICC single measures, 0.83-0.91). The equipment demonstrated excellent reliability, with little difference in the reliability of the five measurement sites. These preliminary findings support their use in future CRPS research. Not applicable. Copyright © 2012 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Breakdown of Magnetic Order in the Pressurized Kitaev Iridate β -Li2IrO3

NASA Astrophysics Data System (ADS)

Majumder, M.; Manna, R. S.; Simutis, G.; Orain, J. C.; Dey, T.; Freund, F.; Jesche, A.; Khasanov, R.; Biswas, P. K.; Bykova, E.; Dubrovinskaia, N.; Dubrovinsky, L. S.; Yadav, R.; Hozoi, L.; Nishimoto, S.; Tsirlin, A. A.; Gegenwart, P.

2018-06-01

Temperature-pressure phase diagram of the Kitaev hyperhoneycomb iridate β -Li2IrO3 is explored using magnetization, thermal expansion, magnetostriction, and muon spin rotation measurements, as well as single-crystal x-ray diffraction under pressure and ab initio calculations. The Néel temperature of β -Li2IrO3 increases with the slope of 0.9 K /GPa upon initial compression, but the reduction in the polarization field Hc reflects a growing instability of the incommensurate order. At 1.4 GPa, the ordered state breaks down upon a first-order transition, giving way to a new ground state marked by the coexistence of dynamically correlated and frozen spins. This partial freezing in the absence of any conspicuous structural defects may indicate the classical nature of the resulting pressure-induced spin liquid, an observation paralleled to the increase in the nearest-neighbor off-diagonal exchange Γ under pressure.

CHARMS: The Cryogenic, High-Accuracy Refraction Measuring System

NASA Technical Reports Server (NTRS)

Frey, Bradley; Leviton, Douglas

2004-01-01

The success of numerous upcoming NASA infrared (IR) missions will rely critically on accurate knowledge of the IR refractive indices of their constituent optical components at design operating temperatures. To satisfy the demand for such data, we have built a Cryogenic, High-Accuracy Refraction Measuring System (CHARMS), which, for typical 1R materials. can measure the index of refraction accurate to (+ or -) 5 x 10sup -3 . This versatile, one-of-a-kind facility can also measure refractive index over a wide range of wavelengths, from 0.105 um in the far-ultraviolet to 6 um in the IR, and over a wide range of temperatures, from 10 K to 100 degrees C, all with comparable accuracies. We first summarize the technical challenges we faced and engineering solutions we developed during the construction of CHARMS. Next we present our "first light," index of refraction data for fused silica and compare our data to previously published results.

Nonlocal Coulomb correlations in pure and electron-doped Sr2IrO4 : Spectral functions, Fermi surface, and pseudo-gap-like spectral weight distributions from oriented cluster dynamical mean-field theory

NASA Astrophysics Data System (ADS)

Martins, Cyril; Lenz, Benjamin; Perfetti, Luca; Brouet, Veronique; Bertran, François; Biermann, Silke

2018-03-01

We address the role of nonlocal Coulomb correlations and short-range magnetic fluctuations in the high-temperature phase of Sr2IrO4 within state-of-the-art spectroscopic and first-principles theoretical methods. Introducing an "oriented-cluster dynamical mean-field scheme", we compute momentum-resolved spectral functions, which we find to be in excellent agreement with angle-resolved photoemission spectra. We show that while short-range antiferromagnetic fluctuations are crucial to accounting for the electronic properties of Sr2IrO4 even in the high-temperature paramagnetic phase, long-range magnetic order is not a necessary ingredient of the insulating state. Upon doping, an exotic metallic state is generated, exhibiting cuprate-like pseudo-gap spectral properties, for which we propose a surprisingly simple theoretical mechanism.

IR-thermography for Quality Prediction in Selective Laser Deburring

NASA Astrophysics Data System (ADS)

Möller, Mauritz; Conrad, Christian; Haimerl, Walter; Emmelmann, Claus

Selective Laser Deburring (SLD) is an innovative edge-refinement process being developed at the Laser Zentrum Nord (LZN) in Hamburg. It offers a wear-free processing of defined radii and bevels at the edges as well as the possibility to deburr several materials with the same laser source. Sheet metal parts of various applications need to be post-processed to remove sharp edges and burrs remaining from the initial production process. Thus, SLD will provide an extended degree of automation for the next generation of manufacturing facilities. This paper investigates the dependence between the deburring result and the temperature field in- and post-process. In order to achieve this, the surface temperature near to the deburred edge is monitored with IR-thermography. Different strategies are discussed for the approach using the IR-information as a quality assurance. Additional experiments are performed to rate the accuracy of the quality prediction method in different deburring applications.

The Infrared Sensor Suite for SnowEx 2017

NASA Technical Reports Server (NTRS)

Hall, D. K.; Chickadel, C. C.; Crawford, C. J.; DeMarco, E. L.; Jennings, D. E.; Jhabvala, M. D.; Kim, E. J.; Lundquist, J. D.; Lunsford, A. W.

2017-01-01

SnowEx is a winter airborne and field campaign designed to measure snow-water equivalent in forested landscapes. A major focus of Year 1 (2016-17) of NASA's SnowEx campaign will be an extensive field program involving dozens of participants from U.S. government agencies and from many universities and institutions, both domestic and foreign. Along with other instruments, two infrared (IR) sensors will be flown on a Naval Research Laboratory P-3 aircraft. Surface temperature is a critical input to hydrologic models and will be measured during the SnowEx mission. A Quantum Well Infrared Photodetector (QWIP) IR imaging camera system will be flown along with a KT-15 remote thermometer to aid in the calibration of the IR image data. Together, these instruments will measure surface temperature of snow and ice targets to an expected accuracy of less than 1C.

Revisiting the Cause of the 1989-2009 Arctic Surface Warming Using the Surface Energy Budget: Downward Infrared Radiation Dominates the Surface Fluxes

NASA Astrophysics Data System (ADS)

Lee, Sukyoung; Gong, Tingting; Feldstein, Steven B.; Screen, James A.; Simmonds, Ian

2017-10-01

The Arctic has been warming faster than elsewhere, especially during the cold season. According to the leading theory, ice-albedo feedback warms the Arctic Ocean during the summer, and the heat gained by the ocean is released during the winter, causing the cold-season warming. Screen and Simmonds (2010; SS10) concluded that the theory is correct by comparing trend patterns in surface air temperature (SAT), surface turbulence heat flux (HF), and net surface infrared radiation (IR). However, in this comparison, downward IR is more appropriate to use. By analyzing the same data used in SS10 using the surface energy budget, it is shown here that over most of the Arctic the skin temperature trend, which closely resembles the SAT trend, is largely accounted for by the downward IR, not the HF, trend.

Observations of Typhoon Center by Using Satellite-derived Normalized Difference Convection Index

NASA Astrophysics Data System (ADS)

Liu, Chung-Chih; Chen, Chun-Hsu

2015-04-01

A technique involving differencing water vapor and infrared window channel brightness temperature values to identify and quantify intense convection in tropical cyclones using bispectral geostationary satellite imagery was proposed by Olander and Velden (2009). Rouse et al. (1974) calculated a normalized ratio of the near infrared and red bands and proposed an index called the normalized difference vegetation index. It was then used in many fields such as estimations of vegetation biomass, leaf area, the proportion of absorbed photosynthetically active radiation, etc. The present study used the spectral features of the IR1 and WV channels of the satellite to define a new index, the brightness temperature of the infrared window channel minus the brightness temperature of the water vapor channel divided by the brightness temperature of the infrared window channel plus the brightness temperature of the water vapor channel. The values obtained by this formula are called the Normalized Difference Convection Index (NDCI) values. The NDCI value is between -1 and 1. The NDCI value at WV = 0K is the highest, 1; while that at IR1 = 0K is the lowest, -1. In cases of a clear sky or atmosphere with thin cloud and dry air, NDCI values should be larger than 0. In cases of a convective cloud system, NDCI values should be lower than 0. In addition, the newly defined NDCI does show significant difference from simple difference of IR1-WV. For example, the NDCI value is -0.0017 at IR1=299K and WV=300K, while the NDCI value is -0.0033 at IR1=149K and WV=150K. The two times difference of NDCI values shows the features of clouds with NDCI value -0.0017 are quite different from those with NDCI value -0.0033. The former may be low level clouds, but the latter may be deep convections. However, the simple difference of IR1-WV cannot be used to distinguish the difference. The NDCI was applied to determine the centers of Typhoon Longwang (2005). The results showed that the two-dimensional NDCI analysis helped to identify positions of overshooting areas. In addition, because the NDCI values near a typhoon eye were rather significant, if a typhoon eye was formed, the NDCI cross-section analysis could help to confirm its position. When the center of a typhoon was covered by the high Anvils and Cirrus Layers, it could still be found qualitatively through the two-dimensional analysis. Keywords:Typhoon, Satellite imagery, Normalized Difference Convection Index

Metal Carbon Eutectics to Extend the Use of the Fixed-Point Technique in Precision IR Thermometry

NASA Astrophysics Data System (ADS)

Battuello, M.; Girard, F.; Florio, M.

2008-06-01

The high-temperature extension of the fixed-point technique for primary calibration of precision infrared (IR) thermometers was investigated both through mathematical simulations and laboratory investigations. Simulations were performed with Co C (1,324°C) and Pd C (1, 492°C) eutectic fixed points, and a precision IR thermometer was calibrated from the In point (156.5985°C) up to the Co C point. Mathematical simulations suggested the possibility of directly deriving the transition temperature of the Co C and Pd C points by extrapolating the calibration derived from fixed-point measurements from In to the Cu point. Both temperatures, as a result of the low uncertainty associated with the In Cu calibration and the high number of fixed points involved in the calibration process, can be derived with an uncertainty of 0.11°C for Co C and 0.18°C for Pd C. A transition temperature of 1,324.3°C for Co C was determined from the experimental verification, a value higher than, but compatible with, the one proposed by the thermometry community for inclusion as a secondary reference point for ITS-90 dissemination, i.e., 1,324.0°C.

Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels

PubMed Central

Khokhlova, Vera A.; Shmeleva, Svetlana M.; Gavrilov, Leonid R.; Martin, Eleanor; Sadhoo, Neelaksh; Shaw, Adam

2013-01-01

Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2 mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1 MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm2 to at least 50 W/cm2. Significantly higher intensities could be measured simply by reducing the duty cycle. PMID:23927199

Infrared mapping of ultrasound fields generated by medical transducers: feasibility of determining absolute intensity levels.

PubMed

Khokhlova, Vera A; Shmeleva, Svetlana M; Gavrilov, Leonid R; Martin, Eleanor; Sadhoo, Neelaksh; Shaw, Adam

2013-08-01

Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2 mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1 MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm(2) to at least 50 W/cm(2). Significantly higher intensities could be measured simply by reducing the duty cycle.

Sr 2IrO 4: Gateway to cuprate superconductivity?

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

Mitchell, J. F.

High temperature superconductivity in cuprates remains a defining challenge in condensed matter physics. Recently, a new set of related compounds based on Ir rather than Cu has been discovered that may be on the verge of superconductivity themselves or be able to shed new light on the underlying interactions responsible for superconductivity in the cuprates.

Two-step recrystallization of water in concentrated aqueous solution of poly(ethylene glycol).

PubMed

Gemmei-Ide, Makoto; Motonaga, Tetsuya; Kasai, Ryosuke; Kitano, Hiromi

2013-02-21

Crystallization behavior of water in a concentrated aqueous solution of poly(ethylene glycol) (PEG) with a water content of 37.5 wt % was investigated by temperature variable mid-infrared (mid-IR) spectroscopy in a temperature range of 298-170 K. The mid-IR spectrum of water at 298 K showed that a large water cluster was not formed and that most of the water molecules were associated with the PEG chain. Ice formation, however, occurred as found in previous studies by differential scanning calorimetory. Ice formations were grouped into three types: crystallization at 231 K during cooling, that at 198 K during heating, and that at 210 K during heating. The latter two were just recrystallization. These ice formations were the direct transition from hydration species to ice without condensation regardless of crystallization or recrystallization. This means that the recrystallized water in the present system was not generated from low-density amorphous solid water. At a low cooling rate, nearly complete crystallization at 231 K during cooling and no recrystallization were observed. At a high cooling rate, no crystallization and two-step recrystallization at 198 and 210 K were observed. The former and latter recrystallizations were found to be generated from water associated with the PEG chains with ttg (the sequence -O-CH(2)-CH(2)-O- having a trans (t) conformation about the -C-O- bond and a gauche (g) conformation about the -C-C- bond) and random conformations, respectively. These results indicate that recrystallizable water does not have a single specific water structure.

Measurement of heating coil temperature for e-cigarettes with a "top-coil" clearomizer.

PubMed

Chen, Wenhao; Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A; Kumagai, Kazukiyo

2018-01-01

To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a "top-coil" clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3-6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such "top-coil" clearomizers. This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices' ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating.

Measurement of heating coil temperature for e-cigarettes with a “top-coil” clearomizer

PubMed Central

Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A.; Kumagai, Kazukiyo

2018-01-01

Objectives To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a “top-coil” clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. Methods The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3–6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). Results For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such “top-coil” clearomizers. Conclusions This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices’ ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating. PMID:29672571

The future of VIS-IR hyperspectral remote sensing for the exploration of the solar system

NASA Astrophysics Data System (ADS)

Filacchione, Gianrico

2017-06-01

In the last 30 years our understanding of the Solar System has greatly advanced thanks to the introduction of VIS-IR imaging spectrometers which have provided hyperspectral views of planets, satellites, asteroids, comets and rings. By providing moderate resolution images and reflectance spectra for each pixel at the same time, these instruments allow to elaborate spectral-spatial models for very different targets: when used to observe surfaces, hyperspectral methods permit to retrieve endmembers composition (minerals, ices, organics, liquids), mixing state among endmembers (areal, intimate, intraparticle), physical properties (particle size, roughness, temperature) and to correlate these quantities with geological and morphological units. Similarly, morphological, dynamical and compositional studies of gaseous and aerosol species can be retrieved for planetary atmospheres, exospheres and auroras. To achieve these results, very different optical layouts, detectors technologies and observing techniques have been adopted in the last decades, going from very large and complex payloads, like ISM (IR Spectral Mapper) on russian mission Phobos to Mars and NIMS (Near IR Mapping Spectrometer) on US Galileo mission to Jupiter, which were the first hyperspectral imagers to flow aboard planetary missions, to more recent compact and performing experiments. The future of VIS-IR hyperspectral remote sensing is challenging because the complexity of modern planetary missions drives towards the realization of increasingly smaller, lighter and more performing payloads able to survive in harsh radiation and planetary protected environments or to operate from demanding platforms like landers, rovers and cubesats. As a development for future missions, one can foresee that apart instruments designed around well-consolidated optical solutions relying on prisms or gratings as dispersive elements, a new class of innovative hyperspectral imagers will rise: recent developments in Optomechatronics (the fusion of Optical and Mechatronic technologies) including the realization of linear variable filters, acusto-optic and liquid crystals tunable filters, micro-opto-mechanical systems (MOEMS) open the possibility to realize completely new imaging spectrometers designs for planetary exploration. The resulting miniaturization of optical and dispers! ive elements with VIS-IR detectors open pathways towards more integrated and compact instruments. Parallel to those developments it will be necessary to develop also new test and calibration setups to be used to characterize this new instrumentation during AIV-AIT phases.

Multi-Sensor Fusion of Infrared and Electro-Optic Signals for High Resolution Night Images

PubMed Central

Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor

2012-01-01

Electro-optic (EO) image sensors exhibit the properties of high resolution and low noise level at daytime, but they do not work in dark environments. Infrared (IR) image sensors exhibit poor resolution and cannot separate objects with similar temperature. Therefore, we propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which improves the resolution of IR images and helps us distinguish objects at night. Our framework superimposing/blending the edges of the EO image onto the corresponding transformed IR image improves their resolution. In this framework, we adopt the theoretical point spread function (PSF) proposed by Hardie et al. for the IR image, which has the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we design an inverse filter for the proposed PSF and use it for the IR image transformation. The framework requires four main steps: (1) inverse filter-based IR image transformation; (2) EO image edge detection; (3) registration; and (4) blending/superimposing of the obtained image pair. Simulation results show both blended and superimposed IR images, and demonstrate that blended IR images have better quality over the superimposed images. Additionally, based on the same steps, simulation result shows a blended IR image of better quality when only the original IR image is available. PMID:23112602

Multi-sensor fusion of infrared and electro-optic signals for high resolution night images.

PubMed

Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor

2012-01-01

Electro-optic (EO) image sensors exhibit the properties of high resolution and low noise level at daytime, but they do not work in dark environments. Infrared (IR) image sensors exhibit poor resolution and cannot separate objects with similar temperature. Therefore, we propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which improves the resolution of IR images and helps us distinguish objects at night. Our framework superimposing/blending the edges of the EO image onto the corresponding transformed IR image improves their resolution. In this framework, we adopt the theoretical point spread function (PSF) proposed by Hardie et al. for the IR image, which has the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we design an inverse filter for the proposed PSF and use it for the IR image transformation. The framework requires four main steps: (1) inverse filter-based IR image transformation; (2) EO image edge detection; (3) registration; and (4) blending/superimposing of the obtained image pair. Simulation results show both blended and superimposed IR images, and demonstrate that blended IR images have better quality over the superimposed images. Additionally, based on the same steps, simulation result shows a blended IR image of better quality when only the original IR image is available.

Temperature dependence of resonant secondary emission in NaNO 2: Spectral behavior

NASA Astrophysics Data System (ADS)

Kato, Riso; Kawaguchi, Yoshizo; Ashida, Masaaki

1990-05-01

Spectral behavior of resonant secondary emission in NaNO 2 has been investigated in the temperature range from 2 to 30 K under the excitation near the v00 line of the lowest singlet absorption. With increasing temperature, luminescence lines separated from multiple-order Raman lines become detectable even under the excitation with the off-resonance energy Δ c ≳ 13 cm -1. The intensity of the luminescence line IL( T) increases with temperature in proportion to the phonon number n( hvp, T) in the temperature range T ≲ Δ c/ k, while it increases more steeply in the range T ≳ Δ c/ k. The temperature dependence of IL( T) is ascribed to the increase in the luminescence from the v00 level after the one-phonon assisted transition to the level induced by the off-resonant incident light. The intensity of the Raman line IR( T) decreases gradually in 2-12 K range and shows rapid drop above 12 K. The temperature dependence of IR( T) is ascribed to the dephasing of the intermediate state due to the two-phonon interaction with the reservoir.

Thermal structure of the Martian atmosphere retrieved from the IR- spectrometry in the 15 mkm CO2 band

NASA Astrophysics Data System (ADS)

Zasova, L.; Formisano, V.; Grassi, D.; Igantiev, N.; Moroz, V.

Thermal IR spectrometry is one of the methods of the Martian atmosphere investigation below 55 km. The temperature profiles retrieved from the 15 μm CO2 band may be used for MIRA database. This approach gives the vertical resolution of several kilometers and accuracy of several Kelvins. An aerosol abundance, which influences the temperature profiles, is obtained from the continuum of the same spectrum. It is taken into account in the temperature retrieval procedure in a self- consistent way. Although this method has limited vertical resolution it possesses some advantages. For example, the radio occultation method gives the temperature profiles with higher spectral resolution, but the radio observations are sparse in space and local time. Direct measurements, which give the most accurate results, enable to obtain the temperature profiles only for some chosen points (landing places). Actually, the thermal IR-spectrometry is the only method, which allows to monitor the temperature profiles with good coverage both in space and local time. The first measurements of this kind were fulfilled by IRIS, installed on board of Mariner 9. This spectrometer was characterized by rather high spectral resolution (2.4 cm-1). The temperature profiles vs. local time dependencies for different latitudes and seasons were retrieved, including dust storm conditions, North polar night, Tharsis volcanoes. The obtained temperature profiles have been compared with the temperature profiles for the same conditions, taken from Climate Data Base (European GCM). The Planetary Fourier Spectrometer onboard Mars Express (which is planned to be launched in 2003) has the spectral range 1.2-45 μm and spectral resolution of 1.5 cm- 1. Temperature retrieval is one of the main scientific goals of the experiment. It opens a possibility to get a series of temperature profiles taken for different conditions, which can later be used in MIRA producing.

186Os-187Os and highly siderophile element abundance systematics of the mantle revealed by abyssal peridotites and Os-rich alloys

NASA Astrophysics Data System (ADS)

Day, James M. D.; Walker, Richard J.; Warren, Jessica M.

2017-03-01

Abyssal peridotites are oceanic mantle fragments that were recently processed through ridges and represent residues of both modern and ancient melting. To constrain the nature and timing of melt depletion processes, and the composition of the mantle, we report high-precision Os isotope data for abyssal peridotites from three ocean basins, as well as for Os-rich alloys, primarily from Mesozoic ophiolites. These data are complemented by whole-rock highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re), trace- and major-element abundances for the abyssal peridotites, which are from the Southwest Indian (SWIR), Central Indian (CIR), Mid-Atlantic (MAR) and Gakkel Ridges. The results reveal a limited role for melt refertilization or secondary alteration processes in modifying abyssal peridotite HSE compositions. The abyssal peridotites examined have experienced variable melt depletion (2% to >16%), which occurred >0.5 Ga ago for some samples. Abyssal peridotites typically exhibit low Pd/Ir and, combined with high-degrees of estimated total melt extraction, imply that they were relatively refractory residues prior to incorporation into their present ridge setting. Recent partial melting processes and mid-ocean ridge basalt (MORB) generation therefore played a limited role in the chemical evolution of their precursor mantle domains. The results confirm that many abyssal peridotites are not simple residues of recent MORB source melting, having a more complex and long-lived depletion history. Peridotites from the Gakkel Ridge, SWIR, CIR and MAR indicate that the depleted MORB mantle has 186Os/188Os of 0.1198356 ± 21 (2SD). The Phanerozoic Os-rich alloys yield an average 186Os/188Os within uncertainty of abyssal peridotites (0.1198361 ± 20). Melt depletion trends defined between Os isotopes and melt extraction indices (e.g., Al2O3) allow an estimate of the primitive mantle (PM) composition, using only abyssal peridotites. This yields 187Os/188Os (0.1292 ± 25), and 186Os/188Os of 0.1198388 ± 29, both of which are within uncertainty of previous primitive mantle estimates. The 186Os/188Os composition of the PM is less radiogenic than for some plume-related lavas, with the latter requiring sources with high long-term time-integrated Pt/Os. Estimates of primitive mantle HSE concentrations using abyssal peridotites define chondritic Pd/Ir, which differs from previous supra-chondritic estimates for Pd/Ir based on peridotites from a range of tectonic settings. By contrast, estimates of PM yield supra-chondritic Ru/Ir. The cause of enhanced Ru in the mantle remains enigmatic, but may reflect variable partitioning behavior of Ru at high pressure and temperature.

Prevalence of Hyperinsulinemia Associated with Body Mass Index, Genetic Predisposition, and Lifestyle in College Freshmen Students

ERIC Educational Resources Information Center

Hopper, Mari K.; Brown, Gordon W.; Funke, Katharine A.; Pike Brown, Leslie R.

2012-01-01

Objective: College lifestyle places an individual at greater risk for the development of insulin resistance (IR) and disease. The aim of this study was to establish a baseline measurement of insulin, and other variables influencing IR in college freshmen. Participants: Twenty-two men and women, 18 to 19 years of age, during first month of college.…

Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

DOEpatents

Westerfield, Curtis L.; Morris, John S.; Agnew, Stephen F.

1997-01-01

Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.

Magnesioferrite from the Cretaceous-Tertiary boundary, Caravaca, Spain

USGS Publications Warehouse

Bohor, B.F.; Foord, E.E.; Ganapathy, R.

1986-01-01

Magnesioferrite grading toward magnetite has been identified as a very small but meaningful constituent of the basal iron-rich portion of the Cretaceous-Tertiary (K-T) boundary clay at the Barranco del Gredero section, Caravaca, Spain. This spinel-type phase and others of the spinel group, found in K-T boundary clays at many widely separated sites, have been proposed as representing unaltered remnants of ejecta deposited from an earth-girdling dust cloud formed from the impact of an asteroid or other large bolide at the end of the Cretaceous period. The magnesioferrite occurs as euhedral, frequently skeletal, micron-sized octahedral crystals. The magnesioferrite contains 29 ?? 11 ppb Ir, which accounts for only part of the Ir anomaly at this K-T boundary layer (52 ?? 1 ppb Ir). Major element analyses of the magnesioferrite show variable compositions. Some minor solid solution exists toward hercynite-spinel and chromite-magnesiochromite. A trevorite-nichromite (NiFe2O4NiCr2O4) component is also present. The analyses are very similar to those reported for sites at Furlo and Petriccio, Umbria, Italy. On the basis of the morphology and general composition of the magnesioferrite grains, rapid crystallization at high temperature is indicated, most likely directly from a vapor phase and in an environment of moderate oxygen fugacity. Elemental similarity with metallic alloy injected into rocks beneath two known impact craters suggests that part of the magnesioferrite may be derived from the vaporized chondritic bolide itself, or from the mantle; there is no supporting evidence for its derivation from crustal target rocks. ?? 1986.

Improvement of Forest Fire Detection Algorithm Using Brightness Temperature Lapse Rate Correction in HIMAWARI-8 IR Channels: Application to the 6 may 2017 Samcheok City, Korea

NASA Astrophysics Data System (ADS)

Park, S. H.; Park, W.; Jung, H. S.

2018-04-01

Forest fires are a major natural disaster that destroys a forest area and a natural environment. In order to minimize the damage caused by the forest fire, it is necessary to know the location and the time of day and continuous monitoring is required until fire is fully put out. We have tried to improve the forest fire detection algorithm by using a method to reduce the variability of surrounding pixels. We focused that forest areas of East Asia, part of the Himawari-8 AHI coverage, are mostly located in mountainous areas. The proposed method was applied to the forest fire detection in Samcheok city, Korea on May 6 to 10, 2017.

Noncontact detection of dry eye using a custom designed infrared thermal image system

NASA Astrophysics Data System (ADS)

Su, Tai Yuan; Hwa, Chen Kerh; Liu, Po Hsuan; Wu, Ming Hong; Chang, David O.; Su, Po Fang; Chang, Shu Wen; Chiang, Huihua Kenny

2011-04-01

Dry eye syndrome is a common irritating eye disease. Current clinical diagnostic methods are invasive and uncomfortable for patients. This study developed a custom designed noncontact infrared (IR) thermal image system to measure the spatial and temporal variation of the ocular surface temperature over a 6-second eye-open period. This research defined two parameters: the temperature difference value and the compactness value to represent the temperature change and the irregularity of the temperature distribution on the tear film. Using these two parameters, this study achieved discrimination results for the dry eye and the normal eye groups; the sensitivity is 0.84, the specificity is 0.83, and the receiver operating characteristic area is 0.87. The results suggest that the custom designed IR thermal image system may be used as an effective tool for noncontact detection of dry eye.

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991

NASA Technical Reports Server (NTRS)

Depaula, Ramon P. (Editor); Udd, Eric (Editor)

1991-01-01

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Nanostructured F doped IrO2 electro-catalyst powders for PEM based water electrolysis

NASA Astrophysics Data System (ADS)

Kadakia, Karan Sandeep; Jampani, Prashanth H.; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Park, Sung Kyoo; Hong, Dae Ho; Chung, Sung Jae; Kumta, Prashant N.

2014-12-01

Fluorine doped iridium oxide (IrO2:F) powders with varying F content ranging from 0 to 20 wt.% has been synthesized by using a modification of the Adams fusion method. The precursors (IrCl4 and NH4F) are mixed with NaNO3 and heated to elevated temperatures to form high surface area nanomaterials as electro-catalysts for PEM based water electrolysis. The catalysts were then coated on a porous Ti substrate and have been studied for the oxygen evolution reaction in PEM based water electrolysis. The IrO2:F with an optimum composition of IrO2:10 wt.% F shows remarkably superior electrochemical activity and chemical stability compared to pure IrO2. The results have also been supported via kinetic studies by conducting rotating disk electrode (RDE) experiments. The RDE studies confirm that the electro-catalysts follow the two electron transfer reaction for electrolysis with calculated activation energy of ∼25 kJ mol-1. Single full cell tests conducted also validate the superior electrochemical activity of the 10 wt.% F doped IrO2.

Very large scale heterogeneous integration (VLSHI) and wafer-level vacuum packaging for infrared bolometer focal plane arrays

NASA Astrophysics Data System (ADS)

Forsberg, Fredrik; Roxhed, Niclas; Fischer, Andreas C.; Samel, Björn; Ericsson, Per; Hoivik, Nils; Lapadatu, Adriana; Bring, Martin; Kittilsland, Gjermund; Stemme, Göran; Niklaus, Frank

2013-09-01

Imaging in the long wavelength infrared (LWIR) range from 8 to 14 μm is an extremely useful tool for non-contact measurement and imaging of temperature in many industrial, automotive and security applications. However, the cost of the infrared (IR) imaging components has to be significantly reduced to make IR imaging a viable technology for many cost-sensitive applications. This paper demonstrates new and improved fabrication and packaging technologies for next-generation IR imaging detectors based on uncooled IR bolometer focal plane arrays. The proposed technologies include very large scale heterogeneous integration for combining high-performance, SiGe quantum-well bolometers with electronic integrated read-out circuits and CMOS compatible wafer-level vacuum packing. The fabrication and characterization of bolometers with a pitch of 25 μm × 25 μm that are arranged on read-out-wafers in arrays with 320 × 240 pixels are presented. The bolometers contain a multi-layer quantum well SiGe thermistor with a temperature coefficient of resistance of -3.0%/K. The proposed CMOS compatible wafer-level vacuum packaging technology uses Cu-Sn solid-liquid interdiffusion (SLID) bonding. The presented technologies are suitable for implementation in cost-efficient fabless business models with the potential to bring about the cost reduction needed to enable low-cost IR imaging products for industrial, security and automotive applications.

Deep convective cloud characterizations from both broadband imager and hyperspectral infrared sounder measurements

NASA Astrophysics Data System (ADS)

Ai, Yufei; Li, Jun; Shi, Wenjing; Schmit, Timothy J.; Cao, Changyong; Li, Wanbiao

2017-02-01

Deep convective storms have contributed to airplane accidents, making them a threat to aviation safety. The most common method to identify deep convective clouds (DCCs) is using the brightness temperature difference (BTD) between the atmospheric infrared (IR) window band and the water vapor (WV) absorption band. The effectiveness of the BTD method for DCC detection is highly related to the spectral resolution and signal-to-noise ratio (SNR) of the WV band. In order to understand the sensitivity of BTD to spectral resolution and SNR for DCC detection, a BTD to noise ratio method using the difference between the WV and IR window radiances is developed to assess the uncertainty of DCC identification for different instruments. We examined the case of AirAsia Flight QZ8501. The brightness temperatures (Tbs) over DCCs from this case are simulated for BTD sensitivity studies by a fast forward radiative transfer model with an opaque cloud assumption for both broadband imager (e.g., Multifunction Transport Satellite imager, MTSAT-2 imager) and hyperspectral IR sounder (e.g., Atmospheric Infrared Sounder) instruments; we also examined the relationship between the simulated Tb and the cloud top height. Results show that despite the coarser spatial resolution, BTDs measured by a hyperspectral IR sounder are much more sensitive to high cloud tops than broadband BTDs. As demonstrated in this study, a hyperspectral IR sounder can identify DCCs with better accuracy.

New insights into the near-IR spectroscopy of the young variable PV Cep

NASA Astrophysics Data System (ADS)

Lorenzetti, D.; Giannini, T.; Antoniucci, S.; Kopatskaya, E. N.; Larionov, V.; Arkharov, A. A.; Di Paola, A.; Nisini, B.

2015-08-01

During our EXor monitoring programme dubbed EXORCISM (EXOR OptiCal and Infrared Systematic Monitoring - Antoniucci et al. 2013 PPVI, Lorenzetti et al. 2007 ApJ 665, 1182), we have been observing the variable source PV Cep (ATel #1256; #1607).

Comparative mapping of serotonin-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

PubMed

Newcomb, James M; Fickbohm, David J; Katz, Paul S

2006-11-20

The serotonergic systems in nudibranch molluscs were compared by mapping the locations of serotonin-immunoreactive (5-HT-ir) neurons in 11 species representing all four suborders of the nudibranch clade: Dendronotoidea (Tritonia diomedea, Tochuina tetraquetra, Dendronotus iris, Dendronotus frondosus, and Melibe leonina), Aeolidoidea (Hermissenda crassicornis and Flabellina trophina), Arminoidea (Dirona albolineata, Janolus fuscus, and Armina californica), and Doridoidea (Triopha catalinae). A nomenclature is proposed to standardize reports of cell location in species with differing brain morphologies. Certain patterns of 5-HT immunoreactivity were found to be consistent for all species, such as the presence of 5-HT-ir neurons in the pedal and cerebral ganglia. Also, particular clusters of 5-HT-ir neurons in the anterior and posterior regions of the dorsal surface of the cerebral ganglion were always present. However, there were interspecies differences in the number of 5-HT-ir neurons in each cluster, and some clusters even exhibited strong intraspecies variability that was only weakly correlated with brain size. Phylogenetic analysis suggests that the presence of particular classes of 5-HT-ir neurons exhibits a great deal of homoplasy. The conserved features of the nudibranch serotonergic system presumably represent the shared ancestral structure, whereas the derived characters suggest substantial independent evolutionary changes in the number and presence of serotonergic neurons. Although a number of studies have demonstrated phylogenetic variability of peptidergic systems, this study suggests that serotonergic systems may also exhibit a high degree of homoplasy in some groups of organisms.

In vivo confocal Raman spectroscopic analysis of the effects of IR radiation in the stratum corneum of human skin (Conference Presentation)

NASA Astrophysics Data System (ADS)

Rajasekaran, Ramu; Bergamo Lopes, Monica; Magrini, Taciana D.; Figueira Lopes Cançado, Ana Clara; Abrahao Martin, Airton

2017-02-01

Stratum Corneum is the outer covering of the body, which serves as a barrier to infection. The composition of the skin changes withexternal environmental factors, such as temperature, sun irradiation, air pollutants, chemical hazards, as well as other factors.Solar radiation,especially IR radiation is being used as medicine for wound healing processes, in cosmetology, in physiotherapy and warming of muscles. Also, it was reported that the IR radiation produces free radicals and the excess production of free radicals causes irreversible damages. It has been reported that heat may be transmitted by IR radiation, which results in raised skin temperature and the chronic heat exposure of human skin may cause alterations. Erythema igne is one such disease known to be caused by chronic heat exposure. Many techniques have been adopted for monitoring the changes in the skin, which includes the tape stripping and biopsy as the primary methodology. However, these in vitro techniques are invasive, time consuming, and may not provide the actual information as in in vivo conditions. Confocal Raman spectroscopy,which is non-invasive and real time was considered as a potential tool for the in vivo analysis of the distribution and characteristics of different metabolic conditions and their variations of the skin. In this regard, we aimed at in vivo characterization of the IR induced changes in the stratum corneum of human volunteers. The results of Raman spectral signatures with respect to the control and IR exposed skin will be discussed.