High-resolution IR Research Articles

A Diagnostic Study of the Intensity of Three Tropical Cyclones in the Australian Region. Part I: A Synopsis of Observed Features of Tropical Cyclone Kathy (1984)

AbstractObjective streamline analyses and digitized high-resolution IR satellite cloud data have been used to examine in detail the changes in the environmental circulation and in the cloud structure that took place in and around Tropical Cyclone Kathy (1984) when it started to intensify, and during its intensification and dissipation stages. The change of low-level circulation around Tropical Cyclone Kathy was measured by the change in the angle of inflow (α4) at a radius of 4° latitude from the cyclone center. When Kathy started to intensify, α4 increased suddenly from 20° to 42.5° in the northerly airstream to the north and northeast of the depression, and decreased to 0° to the south of the depression. At that stage the low-level circulation around the depression appeared as a giant swirl that started some 600 km to the north and northeast of the depression and spiraled inward toward its center, while trade air, which is usually cool, dry, and stable, did not enter the cyclonic circulation. The angle α4 remained the same during intensification. During the dissipation stage, α4 returned to 20° and trade air started to participate in the cyclonic circulation.Satellite cloud data were used to determine the origin, evolution, and importance of the feeder bands in the intensification of the cyclone, to follow the moist near-equatorial air that flowed through them and to estimate the maximum height of cumulonimbi that developed in them, to observe the changes in the convective activity in the central dense overcast (CDO) area, as well as in the area around the CDO. Most of the observed changes in Kathy have also been observed in other tropical cyclones during intensification and dissipation.Using the sequence of observed changes of the circulation and of convective activity in and around the CDO of Kathy, a mathematical model has been developed to forecast the intensity of a tropical cyclone. The model and its application to three tropical cyclones in the Australian region are described in Part II of this paper.

Full State-Resolved Energy Gain Profiles of CO2 (J = 2−80) from Collisions of Highly Vibrationally Excited Molecules. 1. Relaxation of Pyrazine (E = 37900 cm−1)

State-resolved energy gain profiles for "strong" and "weak" collisions of pyrazine (E = 37900 cm(-1)) and CO(2) are reported. Nascent energy profiles for scattered CO(2) (00(0)0, J = 2-64) were measured using high-resolution transient IR absorption spectroscopy at lambda = 2.7 microm. The data are combined with earlier data for CO(2) (J = 58-80) to yield the full state-resolved distribution of scattered CO(2) (00(0)0). The scattered CO(2) (00(0)0, J = 2-80) molecules have a biexponential rotational distribution with T(lowJ) = 437 +/- 50 K for J < 50 and T(highJ) = 1145 +/- 110 K for J > 50. Fitting the data with a two-component exponential model yields CO(2) product distributions with T(rot) = 329 and 1241 K. The cooler distribution accounts for 78% of the scattered population and results from elastic or weakly inelastic collisions that induce very little rotational excitation in CO(2). The hotter distribution involves large changes in CO(2) rotational energy and accounts for 22% of collisions. The relative translational energy of the scattered molecules increases as a function of final CO(2) rotational state with T(rel) = 860 K for J = 2, 1650 K for J = 60, and 5500 K for J = 80. The total rate constant for appearance of scattered CO(2) (00(0)0) is k(app) = (4.8 +/- 1.4) x 10(-10) cm(3) molecule(-1) s(-1), which is approximately 85% of the Lennard-Jones collision rate. Population depletion measurements yield a collision rate of k(dep) = (5.7 +/- 1.8) x 10(-10) cm(3) molecule(-1) s(-1), which is in very good agreement with the Lennard-Jones collision rate. The full energy transfer probability distribution function P(DeltaE) for pyrazine(E)-CO(2) collisions is presented and compared to results from other studies.

Hypoglycaemic effect of comatin, an antidiabetic substance separated from Coprinus comatus broth, on alloxan-induced-diabetic rats

Comatin, an inhibitor of the non-enzymatic glycosylation (NEG) reaction, was isolated from Coprinus comatus fermentation broth by macroporous resin separation, followed by chromatographic purification using a C18 reversed-phase column. The compound was identified as 4,5-dihydroxy-2-methoxy-benzal-dehyde by high-resolution MS, IR, NMR and UV analyses. The hypoglycaemic effect of comatin, on both normal and alloxan-induced-diabetic rats, was investigated in the paper. The blood glucose concentration of normal rats treated by the comatin at 80 mg/kg body weight was reduced from 5.14 mM to 4.28 mM in 3 h. Also, the concentrations of fructosamine, triglycerides and total cholesterol in induced-diabetic rats were significantly decreased. These results indicated that comatin could maintain a low level of blood glucose and improve glucose tolerance. (C) 2009 Elsevier Ltd. All rights reserved.

High-resolution near-IR spectroscopy: from 4m to ELT class telescopes

High-resolution (HR) near-IR spectroscopy is opening new windows in our understanding of several hot topics of modern planet, stellar and extragalactic astrophysics, and it will have a huge impact in the JWST and ALMA era and beyond. The much reduced extinction at these wavelengths allows to pierce the dust embedding those objects which are heavily obscured in the optical. Moreover, at high redshifts several spectral features, commonly exploited when studying local galaxies, are shifted into the near-IR. However, despite its scientific potential, the field of HR IR spectroscopy and its related science is developing very slowly, because of the lack of optimized instruments with the necessary combination of spectral resolution and coverage.

Isolation and Identification of a Novel Aromatic Amine Mutagen Produced by the Maillard Reaction

To clarify the formation of mutagens in the Maillard reaction of glucose and amino acids, 20 amino acids were separately incubated with glucose in the presence or absence of hydroxyl radicals produced by the Fenton reaction. After 1 week at 37 degrees C and pH 7.4, the reaction mixtures of glucose and tryptophan with and without the Fenton reagent showed mutagenicity toward Salmonella typhimurium YG1024 in the presence of a mammalian metabolic system (S9 mix). To identify mutagens in the reaction mixture, blue rayon-adsorbed material from a mixture of glucose, tryptophan, and the Fenton reagent was separated by column chromatography using various solid and mobile phases, and one mutagen, which accounted for 18% of the total mutagenicity of the reaction mixture, was isolated. The chemical structure of the mutagen was determined to be 5-amino-6-hydroxy-8H-benzo[6,7]azepino[5,4,3-de]quinolin-7-one (ABAQ) on the basis of ESI mass, high-resolution APCI mass, (1)H NMR, (13)C NMR, and IR spectral analyses and chemical synthesis of the mutagen. The novel aromatic amine showed high mutagenicity toward S. typhimurium TA98 and YG1024 with S9 mix, inducing 857 revertants of TA98 and 6007 revertants of YG1024/microg, respectively. The mutagenicity of ABAQ was comparable to that of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, which is a mutagenic and carcinogenic hetrocyclic amine in cooked meat and fish formed through the Maillard reaction at high temperature.

Radio planetary nebulae in the Magellanic Clouds

We report the extragalactic radio-continuum detection of 15 planetary nebulae (PNe) in the Magellanic Clouds (MCs) from recent Australia Telescope Compact Array+Parkes mosaic surveys. These detections were supplemented by new and high resolution radio, optical and IR observations which helped to resolve the true nature of the objects. Four of the PNe are located in the Small Magellanic Cloud (SMC) and 11 are located in the Large Magellanic Cloud (LMC). Based on Galactic PNe the expected radio flux densities at the distance of the LMC/SMC are up to ~2.5 mJy and ~2.0 mJy at 1.4 GHz, respectively. We find that one of our new radio PNe in the SMC has a flux density of 5.1 mJy at 1.4 GHz, several times higher than expected. We suggest that the most luminous radio PN in the SMC (N S68) may represent the upper limit to radio peak luminosity because it is ~3 times more luminous than NGC 7027, the most luminous known Galactic PN. We note that the optical diameters of these 15 MCs PNe vary from very small (~0.08 pc or 0.32"; SMP L47) to very large (~1 pc or 4"; SMP L83). Their flux densities peak at different frequencies, suggesting that they may be in different stages of evolution. We briefly discuss mechanisms that may explain their unusually high radio-continuum flux densities. We argue that these detections may help solve the "missing mass problem" in PNe whose central stars were originally 1-8 Msun. We explore the possible link between ionised halos ejected by the central stars in their late evolution and extended radio emission. Because of their higher than expected flux densities we tentatively call this PNe (sub)sample - "Super PNe".

Inferring Convective Weather Characteristics with Geostationary High Spectral Resolution IR Window Measurements: A Look into the Future

Abstract A high spectral resolution geostationary sounder can make spectrally detailed measurements of the infrared spectrum at high temporal resolution, which provides unique information about the lower-tropospheric temperature and moisture structure. Within the infrared window region, many spectrally narrow, relatively weak water vapor absorption lines and one carbon dioxide absorption line exist. Frequent measurement of these absorption lines can provide critical information for monitoring the evolution of the lower-tropospheric thermodynamic state. This can improve short-term convective forecasts by monitoring regions of changing atmospheric stability. While providing valuable observations, the current geostationary sounders are spectrally broad and do not resolve the important spectrally narrow absorption lines needed to observe the planetary boundary layer. The usefulness of high spectral resolution measurements from polar-orbiting instruments has been shown in the literature, as has the usefulness of high temporal resolution measurements from geostationary instruments. Little attention has been given to the combination of high temporal along with high spectral resolution measurements. This paper demonstrates the potential utility of high temporal and high spectral resolution infrared radiances.

A Multi-Wavelength Simultaneous Study of the Composition of the Halley Family Comet 8P/Tuttle

We report on simultaneous optical and infrared observations of the Halley Family comet 8P/Tuttle performed with the ESO Very Large Telescope. Such multi-wavelength and coordinated observations are a good example of what can be done to support space missions. From high resolution optical spectroscopy of the CN (0,0) 388 nm and NH2 (0,9,0) 610 nm bands using UVES at UT2 we determined 12C/13C = 90 ± 10 and 14N/15N = 150 ± 20 in CN and we derived a nuclear spin temperature of NH3 of 29 ± 1 K. These values are similar to those found in Oort-Cloud and Jupiter Family comets. From low resolution long slit spectroscopy with FORS1 at UT2 we determined the CN, C3 and C2 production rates and the parent and daughter scale lengths up to 5.2 105 km tailward. From high resolution IR spectroscopy with CRIRES at UT1 we measured simultaneously the production rates and mixing ratios of H2O, HCN, C2H2, CH4, C2H6, and CH3OH.

Thiazole constrained analogues of the thevinones: synthesis and structure

A simple synthesis of ring-constrained endoethenomorphinans possessing 2'-substituted thiazole ring 4-6 has been achieved by regio- and stereoselective Diels-Alder reaction of thiazolomorphinandienes 1-3 and methyl vinyl ketone in high yield (72, 64 and 87%, respectively). The structure of cycloaddition products was determined by high resolution mass spectrometry (HRMS), IR, 1D and 2D NMR techniques. Double-pulsed field gradient spin-echo-nOe and HMBC were found to be particularly powerful and indispensable tools in the exact structural elucidation of the presented new class of spatially constrained thevinones.

Time-Resolved FTIR Study on the Reaction of CHCl2 with NO2

The environmentally important free radical reaction of chlorinated methyl CHCl2 with NO2 was investigated by step-scan time-resolved FTIR (TR-FTIR) emission spectroscopy. Vibrationally excited products of CHClO, NO, CO, and HCl are observed in the high-resolution IR emission spectra and three possible reaction channels are therefore elucidated. In particular, the product CO is newly detected and the product HCl is identified explicitly as a yield from the CHCl2+NO2 reaction, taking advantage of the sensitive detection of HCl and CO with TR-FTIR. These results are of particular interests to understand the related realistic chemical processes including atmospheric photochemistry, biofuel combustion, waste destruction, and smoking fire.

Complete Thermoelectric Generator Performance Measurement

AbstractThe standardization of thermoelectric generator (TEG) performance measurement is of a major interest for a usage of them in industrial energy harvesting application. The effects influencing the TEG measurement are regarded and are addressed in this article. The dramatic influences of different measurement parameters are pointed out. The output power dependence on the contact pressure is investigated as a major attempt. The influence of contact pressure on the temperature of the TEG-substrate at the hot side is observed with a high resolution IR camera.Different approaches are discussed in order to obtain the accurate efficiency of a TEG. The heat flux method is influenced by many effects that can falsify the results. The Harman method is used as another approach to determine the figure of merit to calculate the efficiency.

Crossed jet reactive scattering dynamics of F+H2O→HF(v,J)+OH:HF(v,J) product quantum state distributions under single-collision conditions

Reactive scattering dynamics of F+H(2)O-->HF+OH have been investigated under single-collision, crossed, supersonic jet conditions at 5.4(1.3) kcalmol, and nascent HF(v,J) rovibrational populations (v<or=2, J<or=17) have been observed via high resolution IR laser absorption methods. Vibrational populations are highly inverted, with 75(2)% and 21(5)% of the observed HF product formed in v=1 and 0, respectively. Small but finite branching [5(1)%] into the v=2 manifold is observed, which is accessible only via the additional center of mass collision energy in the crossed jets. Despite energy constraints associated with substantial vibrational excitation, the reaction dynamics also lead to rotationally hyperthermal HF, with populations observed up to near the energetic limit for each of the v=0,1,2 vibrational manifolds. The trends in these nascent product rovibrational distributions are interpreted in terms of ab initio predictions of a strongly bent, early-barrier transition state and long-range dipole-dipole interactions in the exit channel.

High resolution IR spectrum of the ν8 band of CH2DF: analysis of the interactions with the near vibrational levels

The IR spectrum of the ν8 band of monodeutero methyl fluoride has been recorded with a resolution of 0.004 cm−1 using a Fourier transform spectrometer. The ν8 vibration, of A′′ symmetry species, gives rise to a pure c-type envelope centred at 1298.58 cm−1, resembling a perpendicular band of a prolate symmetric rotor. From the spectral analysis it has been found that ν8 is coupled with ν4 for the low Ka sublevels while for the higher ones other vibrational states, directly or indirectly, are also interacting. For satisfactory reproduction of the rovibrational data of ν8, the Watson's Hamiltonian in the Ir representation has been implemented with interaction parameters, which included first- and second-order a-, b-type and c-type Coriolis couplings with ν4 and ν9, respectively. Being these states also interacting with other levels, the effective spectroscopic parameters of the analysed band up to fourth order have been obtained from a data set formed by the six fundamentals located below 1500 cm−1.

Gas-phase condensation of nanometer- and subnanometer-sized carbon grains and polycyclic aromatic hydrocarbons

Nanometer- and subnanometer-sized carbonaceous particles have been synthesized via gas-phase condensation processes in laser ablation and laser pyrolysis experiments. Depending on the laser power which affects the temperature in the reaction zone, different carbonaceous nanomaterials are obtained. Low temperatures favor the production of polycyclic aromatic hydrocarbons whereas, at comparably higher temperatures, fullerene- or onion-like nanoparticles are formed. To characterize the carbonaceous species, we employed high-resolution transmission electron microscopy, UV/vis and IR absorption spectroscopy, gas and liquid chromatography, as well as matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy.

A Technique to Determine the Radius of Maximum Wind of a Tropical Cyclone

Abstract A simple technique is developed that enables the radius of maximum wind of a tropical cyclone to be estimated from satellite cloud data. It is based on the characteristic cloud and wind structure of the eyewall of a tropical cyclone, after the method developed by Jorgensen more than two decades ago. The radius of maximum wind is shown to be partly dependent on the radius of the eye and partly on the distance from the center to the top of the most developed cumulonimbus nearest to the cyclone center. The technique proposed here involves the analysis of high-resolution IR and microwave satellite imagery to determine these two parameters. To test the technique, the derived radius of maximum wind was compared with high-resolution wind analyses compiled by the U.S. National Hurricane Center and the Atlantic Oceanographic and Meteorological Laboratory. The mean difference between the calculated radius of maximum wind and that determined from observations is 2.8 km. Of the 45 cases considered, the difference in 50% of the cases was ≤2 km, for 33% it was between 3 and 4 km, and for 17% it was ≥5 km, with only two large differences of 8.7 and 10 km.

Dynamics of Weak and Strong Collisions: Highly Vibrationally Excited Pyrazine (E = 37900 cm−1) with DCl

The outcome of energy transfer due to single collisions between highly vibrationally excited pyrazine (E = 37,900 cm(-1)) and DCl is measured for the appearance of individual low-J rotational states of DCl using high-resolution transient IR absorption. Appearance profiles from double-Gaussian transient lineshapes were measured for a number of DCl states with J = 2-12. These data give information on the recoil velocity distributions, appearance rates, and populations of individual states of the scattered molecules. These data complement previous studies on high-J state DCl scattering (Li, Z.; Korobkova, E.; Werner, K.; Shum, L.; Mullin, A. S. J. Chem. Phys. 2005, 123, 174306), and together, they provide a full description of the V-RT collisions with DCl that quench pyrazine(E). Scattered DCl (v = 0) molecules with J = 2-21 are rotationally hot with T(rot) = 880 +/- 100 K. Center-of-mass translational energy distributions are T(rel) approximately 700 K for J < 15. Broader velocity distributions are observed for the J = 15-20 states. The rate constant for V-RT energy transfer is 4.6 x 10(-10) cm(3) molecule(-1) s(-1). This value is a lower limit to the overall rate constant for energy transfer and corresponds to approximately 85% of the Lennard-Jones collision rate. We estimate scattering into the DCl (v = 1) state occurs in approximately 1% of collisions. The energy transfer probability distribution P(DeltaE) is presented and yields DeltaE = 888 cm(-1).

Photoevaporation of Protoplanetary Disks

We present HST NICMOS Paschen α (Paα) images and low- and high-resolution IRS spectra of photoevaporating disk-tail systems originally detected at 24 μm near O stars. We find no Paα emission in any of the systems. The resulting upper limits correspond to about (2–3) × 10−6 M☉ of mass in hydrogen in the tails, suggesting that the gas is severely depleted. The IRAC data and the low-resolution 5-12 μm IRS spectra provide evidence for an inner disk, while high-resolution long-wavelength (14-30 μm) IRS spectra confirm the presence of a gas-free tail that consists of ~0.01 to ~1 μm dust grains originating in the outer parts of the circumstellar disks. Overall, our observations support theoretical predictions in which photoevaporation removes the gas relatively quickly (≤105 yr) from the outer region of a protoplanetary disk, but leaves an inner, more robust, and possibly gas-rich disk component of radius 5-10 AU. With the gas gone, larger solid bodies in the outer disk can experience a high rate of collisions and produce elevated amounts of dust. This dust is being stripped from the system by the photon pressure of the O star to form a gas-free dusty tail.

Ergosta-4,6,8(14),22-tetraen-3-one from Vietnamese Xylaria sp. possessing inhibitory activity of nitric oxide production

From the methanolic extract of Xylaria sp. collected in Vietnam, a fluorescent constituent, ergosta-4,6,8(14),22-tetraen-3-one (1) was isolated and elucidated by the combination of 2D NMR, high resolution MS, IR and UV spectroscopy. Its inhibitory activity of nitric oxide production in RAW 264.7 cells stimulated by lipopolysaccharide was examined and showed a potential activity with the IC50 value of 28.96 µM.

Energy-dependent dynamics of large-ΔE collisions: Highly vibrationally excited azulene (E=20390 and 38580cm−1) with CO2

We report the energy dependence of strong collisions of CO(2) with highly vibrationally excited azulene for two initial energies, E=20 390 and 38 580 cm(-1). These studies show that both the distribution of transferred energy and the energy transfer rates are sensitive to the azulene energy. Highly excited azulene was prepared in separate studies by absorption of pulsed excitation at lambda=532 or 266 nm, followed by rapid radiationless decay from S(1) or S(4) to vibrationally excited levels of the ground electronic state. The appearance of scattered CO(2) (00(0)0) molecules with E(rot)>1000 cm(-1) was monitored by high-resolution transient IR absorption at lambda=4.3 mum. The average rotational and translational energies of the scattered CO(2) molecules double when the azulene energy is increased by a factor of 2. The rate of energy transfer in strong collisions increases by nearly a factor of 4 when the azulene energy is doubled. The energy transfer probability distribution function for DeltaE>3000 cm(-1) at each initial energy is an exponential decay with curvature that correlates with the energy dependence of the state density, in excellent agreement with predictions from GRETCHEN, a model based on Fermi's golden rule to describe collisional quenching of highly excited molecules.

Thermal evolution of the chemical structure and properties of silicon oxides

High-resolution IR spectroscopic study has shown that stepwise heating of samples of silicon oxides in the temperature range from 50 to 1000°C is accompanied by accumulation of electronically excited states in the skeletal Si-O bond system, as well as by formation of associates in the cationic and anionic sublattices. Stationary association process and cooperative interaction of the excited states give rise to IR luminescence and diamagnetic response which increases as the temperature rises. Accumulation of the excited states in the chemical structure and their relaxation, including that occurring due to thermal desorption of singlet oxygen, are characterized by nonmonotonic temperature dependence of the heat capacity.