The Experts below are selected from a list of 49845 Experts worldwide ranked by ideXlab platform
Ronald K Hanson - One of the best experts on this subject based on the ideXlab platform.
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R-branch line intensities and temperature-dependent line broadening and shift coefficients of the nitric oxide fundamental rovibrational band
Journal of Quantitative Spectroscopy & Radiative Transfer, 2019Co-Authors: Christopher A Almodovar, Christopher L. Strand, Ronald K HansonAbstract:Abstract Two quantum cascade lasers were used to measure line intensities and line shape parameters of nitric oxide rovibrational transitions in the R-branch of the fundamental band near 1900 cm − 1 in a heated Static Cell with temperatures from 294 to 802 K and in a shock tube from 1000 to 2500 K. Pressure in the Static Cell and shock tube experiments ranged from 0.025 to 1 atm and 1.5 to 3.2 atm, respectively. Collision broadening and pressure shift coefficients along with their temperature dependence were determined for nitrogen, argon, and air collision partners. The line shapes of high J” rovibrational transitions (i.e. R(39.5)–R(43.5)) were measured for the first time at elevated temperatures, where these transitions become sufficiently strong. Additionally, several hot band transitions were measured. Measured line intensities show good agreement with those measured by other researchers and tabulated in the HITRAN databases. Comparisons between the temperature exponents measured in the Static Cell and shock tube provide evidence that the power law often used to define the temperature dependence of collisional effects does not hold outside the temperature range studied.
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two color laser absorption near 5 μm for temperature and nitric oxide sensing in high temperature gases
Journal of Quantitative Spectroscopy & Radiative Transfer, 2017Co-Authors: Christopher A Almodovar, Mitchell R Spearrin, Ronald K HansonAbstract:Abstract An infrared laser-absorption technique for in situ temperature and nitric oxide species sensing in high-temperature gases is presented. A pair of quantum cascade lasers in the mid-infrared near 5 μm were utilized to probe rovibrational transitions in nitric oxide's fundamental band. The line parameters of the selected transitions, including line strengths and collision broadening coefficients of nitric oxide with argon and nitrogen, were evaluated during controlled room-temperature Static Cell experiments and high-temperature shock tube experiments at temperatures between 1000 and 3000 K, and pressures between 1 and 5 atm. These studies provided new insights into the temperature dependence of nitric oxide collision broadening, highlighting the inadequacies of the power law over a broad temperature range. With an accurate spectroscopic model over a broad temperature range, the quantitative two-color temperature sensing strategy was demonstrated in non-reactive shock tube experiments from 1000 to 3000 K to validate thermometry and during a nitric oxide formation experiment near 1700 K and 4 atm to highlight capability for temporally-resolved species measurements at MHz rates. The technique has applicability for sensing in a broad range of flow fields that involve high-temperature air.
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diode laser measurements of linestrength and temperature dependent lineshape parameters of h2o co2 and n2 perturbed h2o transitions near 2474 and 2482 nm
Journal of Quantitative Spectroscopy & Radiative Transfer, 2013Co-Authors: Christopher S Goldenstein, Jay B Jeffries, Ronald K HansonAbstract:Abstract Absorption lineshapes for two unresolved H2O doublets near 4029.52 and 4041.92 cm−1 were measured at high-resolution in a heated Static Cell using two distributed-feedback diode lasers. Measurements were acquired for H2O, CO2, and N2 perturbers over a temperature and pressure range of 650–1325 K and 2–760 Torr, respectively. Strong collisional narrowing effects were observed in CO2 and N2, but not in pure H2O. The Galatry profile was used to infer collisional-broadening and -narrowing coefficients and their respective temperature dependence for CO2 and N2 perturbers. The collisional-broadening and -narrowing coefficients for CO2 perturbers were found to decrease with increasing temperature in a similar manner. For N2 perturbers, the collisional-broadening coefficients increased with temperature while the collisional-narrowing coefficients decreased with increasing temperature. Self-broadening coefficients were inferred from Voigt profile fits and are compared with HITEMP 2010. The linestrengths of 17 H2O transitions are also reported.
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tdl absorption sensor for temperature measurements in high pressure and high temperature gases
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012Co-Authors: Christopher S Goldenstein, Ian A Schultz, Jay B. B. Jeffries, Ronald K HansonAbstract:The development and demonstration of a tunable diode laser (TDL) absorption sensor for temperature measurements in high-pressure and high-temperature gases is presented. This sensor uses a wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) technique with a sensor bandwidth of 10 kHz. Two-color thermometry was performed using water vapor absorption features near 1392 and 1469 nm. Sensor performance was validated with measurements in a heated Static Cell and shock-heated N2-H2O mixtures in the Stanford High-Pressure Shock Tube (HPST). Experiments were conducted at gas temperatures and pressures between 600-2200 K and 2-22 atm, respectively.
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co2 concentration and temperature sensor for combustion gases using diode laser absorption near 2 7 μm
Applied Physics B, 2008Co-Authors: Aamir Farooq, Jay B Jeffries, Ronald K HansonAbstract:A new tunable diode-laser sensor based on CO2 absorption near 2.7 μm is developed for high-resolution absorption measurements of CO2 concentration and temperature. The sensor probes the R(28) and P(70) transitions of the ν1+ν3 combination band of CO2 that has stronger absorption line-strengths than the bands near 1.5 μm and 2.0 μm used previously to sense CO2 in combustion gases. The increased absorption strength of transitions in this new wavelength range provides greatly enhanced sensitivity and the potential for accurate measurements in combustion gases with short optical path lengths. Simulated high-temperature spectra are surveyed to find candidate CO2 transitions isolated from water vapor interference. Measurements of line-strength, line position, and collisional broadening parameters are carried out for candidate CO2 transitions in a heated Static Cell as a function of temperature and compared to literature values. The accuracy of a fixed-wavelength CO2 absorption sensor is determined via measurement of known temperature and CO2 mole fraction in a Static Cell and shock-tube. Absorption measurements of CO2 are then made in a laboratory flat-flame burner and in ignition experiments of shock-heated n-heptane/O2/argon mixtures to illustrate the potential of this sensor for combustion and reacting-flow applications.
Scott T. Sanders - One of the best experts on this subject based on the ideXlab platform.
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H 2 O absorption thermometry accuracy in the 7321-7598 cm -1 range studied in a heated Static Cell at temperatures up to 1723 K
Journal of Quantitative Spectroscopy & Radiative Transfer, 2018Co-Authors: Scott T. Melin, Scott T. SandersAbstract:Abstract Gas temperature may be inferred by comparing smoothed measurements of absorption spectra spanning >100 cm−1 to smoothed simulations of the same. Using this thermometry approach in a heated Static Cell at temperatures up to 1723 K, we studied H2O vapor absorption near 7450 cm−1, dominated by features in the R-branch of the v1 + v3 absorption band. In a first experiment, the Cell was operated at 1200–1723 K and 0.0235 bar, while a commercial external cavity diode laser scanned the 7321–7598 cm−1 range. Temperatures inferred from the measured spectra using BT2 simulations were, on average, within 2 K of the actual Cell temperature and fell within the limits of error (±0.5% of reading) for the thermocouple used to monitor gas Cell temperature. Temperatures inferred using HITEMP2010 simulations were, on average, 38 K lower than actual Cell temperatures. In a second experiment, the Cell was operated at 296–1723 K and 1 bar while a swept-wavelength laser monitored the 7347–7536 cm−1 range at 10 kHz repetition rate. Temperatures inferred using BT2 simulations were within 3 K of the actual Cell temperatures, within the limits of error for the gas Cell thermocouple measurements.
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gas Cell based on optical contacting for fundamental spectroscopy studies with initial reference absorption spectrum of h2o vapor at 1723 k and 0 0235 bar
Journal of Quantitative Spectroscopy & Radiative Transfer, 2016Co-Authors: Scott T. Melin, Scott T. SandersAbstract:Abstract A gas Cell, using optically contacted sapphire windows to form a hot vapor seal, has been created for high temperature fundamental spectroscopy studies. It is designed to operate at temperatures from 280–2273 K and pressures from vacuum to 1.3 bar. Using the Cell in conjunction with an external cavity diode laser spectrometer, a reference H2O vapor absorption spectrum at P=0.0235±0.0036 bar and T=1723±6 K was measured with 0.0001 cm−1 resolution over the 7326–7598 cm−1 range. Comparison of the measured spectrum to simulations reveals errors in both the HITEMP and BT2 databases. This work establishes heated Static Cell capabilities at temperatures well above the typical limit of approximately 1300 K set by quartz material properties. This paper addresses the design of the Cell as well as the Cell׳s limitations.
Rolf Bänteli - One of the best experts on this subject based on the ideXlab platform.
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synthesis and biological evaluation of a potent e selectin antagonist
Journal of Medicinal Chemistry, 1999Co-Authors: Gebhard Thoma, Willy Kinzy, John L Magnani, John T. Patton, Christian Bruns, Rolf BänteliAbstract:An early step of the inflammatory responsethe rolling of leukocytes on activated endothelial Cellsis mediated by selectin/carbohydrate interactions. The tetrasaccharide sialyl Lewisx (sLex) 1 is a ligand for E-, P-, and L-selectin and, therefore, serves as a lead structure to develop analogues which allow the control of acute and chronic inflammation. Here we describe the efficient synthesis (10 linear steps) of the potent sLex mimetic 2. Compared to sLex, compound 2 showed a 30-fold improved affinity in a Static, Cell-free E-selectin-ligand binding assay (IC50 = 36 μM). These data were confirmed by a marked inhibition in an in vitro Cell−Cell rolling assay which simulates in vivo conditions (IC50 ≈ 40 μM). The assays are predictive for the in vivo efficacy of test compounds as indicated by a marked inhibitory effect of 2 in a thioglycollate induced peritonitis model of acute inflammation in mice (ED50 ≈ 15 mg/kg).
Scott T. Melin - One of the best experts on this subject based on the ideXlab platform.
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H 2 O absorption thermometry accuracy in the 7321-7598 cm -1 range studied in a heated Static Cell at temperatures up to 1723 K
Journal of Quantitative Spectroscopy & Radiative Transfer, 2018Co-Authors: Scott T. Melin, Scott T. SandersAbstract:Abstract Gas temperature may be inferred by comparing smoothed measurements of absorption spectra spanning >100 cm−1 to smoothed simulations of the same. Using this thermometry approach in a heated Static Cell at temperatures up to 1723 K, we studied H2O vapor absorption near 7450 cm−1, dominated by features in the R-branch of the v1 + v3 absorption band. In a first experiment, the Cell was operated at 1200–1723 K and 0.0235 bar, while a commercial external cavity diode laser scanned the 7321–7598 cm−1 range. Temperatures inferred from the measured spectra using BT2 simulations were, on average, within 2 K of the actual Cell temperature and fell within the limits of error (±0.5% of reading) for the thermocouple used to monitor gas Cell temperature. Temperatures inferred using HITEMP2010 simulations were, on average, 38 K lower than actual Cell temperatures. In a second experiment, the Cell was operated at 296–1723 K and 1 bar while a swept-wavelength laser monitored the 7347–7536 cm−1 range at 10 kHz repetition rate. Temperatures inferred using BT2 simulations were within 3 K of the actual Cell temperatures, within the limits of error for the gas Cell thermocouple measurements.
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gas Cell based on optical contacting for fundamental spectroscopy studies with initial reference absorption spectrum of h2o vapor at 1723 k and 0 0235 bar
Journal of Quantitative Spectroscopy & Radiative Transfer, 2016Co-Authors: Scott T. Melin, Scott T. SandersAbstract:Abstract A gas Cell, using optically contacted sapphire windows to form a hot vapor seal, has been created for high temperature fundamental spectroscopy studies. It is designed to operate at temperatures from 280–2273 K and pressures from vacuum to 1.3 bar. Using the Cell in conjunction with an external cavity diode laser spectrometer, a reference H2O vapor absorption spectrum at P=0.0235±0.0036 bar and T=1723±6 K was measured with 0.0001 cm−1 resolution over the 7326–7598 cm−1 range. Comparison of the measured spectrum to simulations reveals errors in both the HITEMP and BT2 databases. This work establishes heated Static Cell capabilities at temperatures well above the typical limit of approximately 1300 K set by quartz material properties. This paper addresses the design of the Cell as well as the Cell׳s limitations.
Christopher S Goldenstein - One of the best experts on this subject based on the ideXlab platform.
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diode laser measurements of linestrength and temperature dependent lineshape parameters of h2o co2 and n2 perturbed h2o transitions near 2474 and 2482 nm
Journal of Quantitative Spectroscopy & Radiative Transfer, 2013Co-Authors: Christopher S Goldenstein, Jay B Jeffries, Ronald K HansonAbstract:Abstract Absorption lineshapes for two unresolved H2O doublets near 4029.52 and 4041.92 cm−1 were measured at high-resolution in a heated Static Cell using two distributed-feedback diode lasers. Measurements were acquired for H2O, CO2, and N2 perturbers over a temperature and pressure range of 650–1325 K and 2–760 Torr, respectively. Strong collisional narrowing effects were observed in CO2 and N2, but not in pure H2O. The Galatry profile was used to infer collisional-broadening and -narrowing coefficients and their respective temperature dependence for CO2 and N2 perturbers. The collisional-broadening and -narrowing coefficients for CO2 perturbers were found to decrease with increasing temperature in a similar manner. For N2 perturbers, the collisional-broadening coefficients increased with temperature while the collisional-narrowing coefficients decreased with increasing temperature. Self-broadening coefficients were inferred from Voigt profile fits and are compared with HITEMP 2010. The linestrengths of 17 H2O transitions are also reported.
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tdl absorption sensor for temperature measurements in high pressure and high temperature gases
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012Co-Authors: Christopher S Goldenstein, Ian A Schultz, Jay B. B. Jeffries, Ronald K HansonAbstract:The development and demonstration of a tunable diode laser (TDL) absorption sensor for temperature measurements in high-pressure and high-temperature gases is presented. This sensor uses a wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) technique with a sensor bandwidth of 10 kHz. Two-color thermometry was performed using water vapor absorption features near 1392 and 1469 nm. Sensor performance was validated with measurements in a heated Static Cell and shock-heated N2-H2O mixtures in the Stanford High-Pressure Shock Tube (HPST). Experiments were conducted at gas temperatures and pressures between 600-2200 K and 2-22 atm, respectively.