Near-infrared spectroscopy of PKS 1549-79: a protoquasar revealed?

We present a near-infrared (near-IR) spectrum of the nearby radio galaxy PKS 1549-79 (z = 0.153). These data were taken with the aim of testing the idea that this object contains a quasar nucleus that is moderately extinguished, despite evidence that its radio jet points close to our line of sight. We detect broad Paalpha emission (FWHM 1745 +/- 40 km s(-1)), relatively bright continuum emission, and a continuum slope consistent with a reddened quasar spectrum (3.1 <A(V) <7.3), all emitted by an unresolved point source. Therefore we conclude that we have, indeed, detected a hidden quasar nucleus in PKS 1549-79. Combined with previous results, these observations are consistent with the idea that PKS 1549-79 is a young radio source in which the cocoon of debris left over from the triggering events has not yet been swept aside by circumnuclear outflows.

Determination of higher heating value of petro-diesels using mid-infrared spectroscopy and chemometry

Higher heating value (HHV) is probably the most important property of the fuels. Bomb calorimeter and derived empirical formulae are often used for accurate determination of HHV of fuels. A useful empirical equation was derived to estimate HHV of petro-diesels from their C and H contents: HHV (in MJ/kg) = 0.3482(C) + 1.1887(H), r (2) = 0.9956. The derived correlation was validated against the most common formulae in the literature, Boie and Channiwala-Parikh correlations. Accordingly, accurate determination of C and H contents is essential for estimation of HHV and avoids using a bomb calorimeter. However, accurate estimation of C and H contents requires using expensive and laborious gas chromatographic techniques. In this work, chemometry offered a simple method for HHV determination of petro-diesels without using bomb calorimeter or even gas chromatography. PLS-1 calibration was used instead of gas chromatography to find C and H contents from the non-selective mid-infrared (MIR) spectra of petro-diesels, HHV was then estimated from the earlier empirical equation. The proposed method predicts HHV of petro-diesels with high accuracy and precision, with modest analysis costs. The present method may be extended to other fuels.

Optical and infrared spectroscopy of the type IInSN1998S: days 3-127

We present contemporary optical and infrared spectroscopic observations of the type IIn SN 1998S covering the period between 3 and 127 days after discovery. During the first week the spectra are characterized by prominent broad H, He and C III/N III emission lines with narrow peaks, superimposed on a very blue continuum (T similar to 24 000 K). In the following two weeks the C III/N III emission vanished, together with the broad emission components of the H and He lines. Broad, blueshifted absorption components appeared in the spectra. The temperature of the continuum also dropped to similar to 14000 K. By the end of the first month the spectrum comprised broad, blueshifted absorptions in H, He, Si II, Fe II and Sc II. By day 44, broad emission components in H and He reappeared in the spectra. These persisted to as late as days similar to 100-130, becoming increasingly asymmetric. We agree with Leonard et al. that the broad emission lines indicate interaction between the ejecta and circumstellar material (CSM) emitted by the progenitor. We also agree that the progenitor of SN 1998S appears to have gone through at least two phases of mass-loss, giving rise to two CSM zones. Examination of the spectra indicates that the inner zone extended to less than or equal to 90 au, while the outer CSM extended from 185 an to over 1800 au.

The prediction of intake potential and organic matter digestibility of grass silages by near infrared spectroscopy analysis of undried samples

A study was undertaken to examine a range of sample preparation and near infrared reflectance spectroscopy (NIPS) methodologies, using undried samples, for predicting organic matter digestibility (OMD g kg(-1)) and ad libitum intake (g kg(-1) W-0.75) of grass silages. A total of eight sample preparation/NIRS scanning methods were examined involving three extents of silage comminution, two liquid extracts and scanning via either external probe (1100-2200 nm) or internal cell (1100-2500 nm). The spectral data (log 1/R) for each of the eight methods were examined by three regression techniques each with a range of data transformations. The 136 silages used in the study were obtained from farms across Northern Ireland, over a two year period, and had in vivo OMD (sheep) and ad libitum intake (cattle) determined under uniform conditions. In the comparisons of the eight sample preparation/scanning methods, and the differing mathematical treatments of the spectral data, the sample population was divided into calibration (n = 91) and validation (n = 45) sets. The standard error of performance (SEP) on the validation set was used in comparisons of prediction accuracy. Across all 8 sample preparation/scanning methods, the modified partial least squares (MPLS) technique, generally minimized SEP's for both OMD and intake. The accuracy of prediction also increased with degree of comminution of the forage and with scanning by internal cell rather than external probe. The system providing the lowest SEP used the MPLS regression technique on spectra from the finely milled material scanned through the internal cell. This resulted in SEP and R-2 (variance accounted for in validation set) values of 24 (g/kg OM) and 0.88 (OMD) and 5.37 (g/kg W-0.75) and 0.77 (intake) respectively. These data indicate that with appropriate techniques NIRS scanning of undried samples of grass silage can produce predictions of intake and digestibility with accuracies similar to those achieved previously using NIRS with dried samples. (C) 1998 Elsevier Science B.V.

Use of Short Time-on-Stream Attenuated Total Internal Reflection Infrared Spectroscopy To Probe Changes in Adsorption Geometry for Determination of Selectivity in the Hydrogenation of Citral

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A new experimental procedure based on attenuated total reflection infrared spectroscopy has been developed to investigate surface species under liquid phase reaction conditions. The technique has been tested by investigating the enhanced selectivity in the hydrogenation of α,β-unsaturated aldehyde citral over a 5% Pt/SiO2 catalyst toward unsaturated alcohols geraniol/nerol, which occurs when citronellal is added to the reaction. The change in selectivity is proposed to be the result of a change in the citral adsorption mode in the presence of citronellal. Short time on stream attenuated total internal reflection infrared spectroscopy has allowed identification of the adsorption modes of citral. With no citronellal, citral adsorbs through both the C═C and C═O groups; however, in the presence of citronellal, citral adsorption occurs through the C═O group only, which is proposed to be the cause of the altered reaction selectivity.

Perturbed frequency-selective surfaces fabricated on large thin polymer membranes for multiband infrared applications

The design, fabrication, and characterization of single-screen perturbed frequency-selective surfaces (FSS) at infrared frequencies for single and multiband applications are reported. Single-band FSS based on parallel strips have been perturbed by decreasing the length of every second strip within the array in order to achieve dual band-stop responses. The same principle has been extended to design FSS exhibiting tri- and quadreflection bands. In addition, strip FSSs have been perturbed by replacing every second strip for a metallic ring, resulting in dual-band filters with different polarization responses of the bands. These designs have been fabricated on large thin polyimide membranes using sacrificial silicon wafers. An oxide interlayer between the sacrificial silicon wafer and the polyimide membrane is employed to stop the silicon etching and is wet etched subsequently by a solution of ammonium fluoride and acetic acid that does not attack either the polyimide membrane or the aluminium FSS elements. Fourier transform infrared spectroscopy measurements are presented to validate the predicted responses of the fabricated prototypes.

Temperature dependence of the mid-infrared dielectric function of YBCO in the ab plane

We have excited mid-infrared surface plasmons in two YBCO thin films of contrasting properties using attenuated total reflection of light and found that the imaginary part of the dielectric function decreases linearly with reduction in temperature. This result is in contrast with the commonly reported conclusion of infrared normal reflectance studies. If sustained it may clarify the problem of understanding the normal state properties of YBCO and the other cuprates. The dielectric function of the films, epsilon = epsilon(1) + i epsilon(2), was determined between room temperature and 80K: epsilon(1) was found to be only slightly temperature dependent but somewhat sample dependent, probably as a result of surface and grain boundary contamination. The imaginary part, epsilon(2), (and the real part of the conductivity, sigma(1),) decreased linearly with reduction in temperature in both films. Results obtained were: for film 1: epsilon(1) = - 14.05 - 0.0024T and epsilon(2) - 4.11 + 0.086T and for film 2: epsilon(1) = - 24.09 + 0.0013T and epsilon(2) = 7.66 + 0.067T where T is the temperature in Kelvin. An understanding of the results is offered in terms of temperature-dependent intrinsic intragrain inelastic scattering and temperature-independent contributions: elastic and inelastic grain boundary scattering and optical interband (or localised charge) absorption. The relative contribution of each is estimated. A key conclusion is that the interband (or localised charge) absorption is only similar to 10%. Most importantly, the intrinsic scattering rate, 1/tau, decreases linearly with fall in temperature, T, in a regime where current theory predicts dependence on frequency, omega, to dominate. The coupling constant, lambda, between the charge carriers and the thermal excitations has a value of 1.7, some fivefold greater than the far infrared value. These results imply a need to restate the phenomenology of the normal state of high temperature superconductors and seek a corresponding theoretical understanding.

Physicochemical Characterization of Poly(ethylene glycol) Plasticized Poly(methyl vinyl ether-co-maleic acid) Films

The influence of the poly(ethylene glycol) (PEG) plasticizer content and molecular weight on the physicochemical properties of films cast from aqueous blends of poly(methyl vinyl ether-co-maleic acid) (PMVE/MA) was investigated with tensile mechanical testing, thermal analysis, and attenuated total reflectance/Fourier transform infrared spectroscopy. Unplasticized films and those containing high copolymer contents were very difficult to handle and proved difficult to test. PEG with a molecular weight of 200 Da was the most efficient plasticizer. However, films cast from aqueous blends containing 10% (w/w) PMVE/MA and either PEG 1000 or PEG 10,000 when the copolymer/plasticizer ratio was 4 : 3 and those cast from aqueous blends containing 15% (w/w) PMVE/MA and either PEG 1000 or PEG 10,000 when the copolymer/plasticizer ratio was 2 : 1 possessed mechanical properties most closely mimicking those of a formulation we have used clinically in photodynamic therapy. Importantly, we found previously that films cast from aqueous blends containing 10% (w/w) PMVE/MA performed rather poorly in the clinical setting, where uptake of moisture from patients' skin led to reversion of the formulation to a thick gel. Consequently, we are now investigating films cast from aqueous blends containing 15% (w/w) PMVE/MA and either PEG 1000 or PEG 10,000, where the copolymer/plasticizer ratio is 2 : 1, as possible Food and Drug Administration approved replacements for our current formulation, which must currently be used only on a named patient basis as its plasticizer, tripropylene glycol methyl ether, is not currently available in pharmaceutical grade

Reduction of Staphylococcus aureus and Pseudomonas aeruginosa colonisation on PVC through covalent surface attachment of fluorinated thiols

OBJECTIVES: This study reports the development, characterisation and microbiological testing of surface-modified polyvinylchloride (PVC) films for the purpose of reducing bacterial adherence.

METHODS: Irreversible covalent surface modification was achieved via nucleophilic substitution of fluorinated thiol-terminated compounds onto the polymer backbone. Four fluorinated modifiers, 2,3,5,6-tetrafluorothiophenol (TFTP), 4-(trifluoromethyl)thiophenol (TFMTP), 3,5-bis(trifluoromethyl)benzenethiol (BTFMBT) and 3,3,4,4,5,5,6,6,7, 7,8,8,9,9,10,10,10-heptadecafluoro-decane-1-thiol (HDFDT), were investigated. Modification was confirmed using attenuated total reflectance infrared spectroscopy; Raman mapping demonstrated that modification was homogenous on the macroscopic scale. The influence of fluorination on surface hydrophobicity was studied by contact angle analysis. The effect on microbial adherence was examined using Pseudomonas aeruginosa and Staphylococcus aureus.

KEY FINDINGS: The resultant changes in contact angle relative to control PVC ranged from -4 degrees to +14 degrees . In all cases, adherence of P. aeruginosa and S. aureus was significantly reduced relative to control PVC, with adherence levels ranging from 62% and 51% for TFTP-modified PVC to 32% and 7% for TFMTP-modified PVC.

CONCLUSIONS: These results demonstrate an important method in reducing the incidence of bacterial infection in PVC medical devices without compromising mechanical properties.

Characterization of silica-supported dodecatungstic heteropolyacids as a function of their dehydroxylation temperature

Dodecatungsto-silicic H4SiW12O40 and -phosphoric acids H3PW12O40 were deposited on silica by a classical impregnation technique. The resulting materials were studied by in situ Raman and infrared spectroscopy, XPS and by solid-state H-1 MAS NMR as a function of their dehydroxylation temperature. The data show that in the case of H3PW12O40 three silanol groups are protonated while in the case of H4SiW12O40 at least one acidic proton remains. Upon heating this proton reacts leading to a disordered structure and a broadening of the W-O Raman bands.

Ionic liquids as solvent and solvent additives for the synthesis of sol-gel materials

The ionic liquid (IL) 1-butyl-3-methylimidazolium chloride was used as a drying control chemical additive in the synthesis of silica sol-gel materials with and without methanol as a co-solvent. The resulting gels were characterized by using thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy and water sorption kinetics. Calcined gels were analyzed using scanning electron microscopy and nitrogen adsorption isotherms for surface area and pore volume determination. Non-calcined gels were monolithic and showed general cloudiness with lesser degrees observed at higher IL volumes. Calcinations resulted in the formation of powders with increased available surface area as the amount of IL volume was increased. This is consistent with an increase in respective pore volume but a general decrease in average pore size. The resulting materials exhibited conventional structural microdomains, in contrast to periodicity reported when other ionic liquids were used as templates.

Adsorption mechanisms of removing heavy metals and dyes from aqueous solution using date pits solid adsorbent

A potential usefulness of raw date pits as an inexpensive solid adsorbent for methylene blue (MB), copper ion (Cu2+), and cadmium ion (Cd2+) has been demonstrated in this work. This work was conducted to provide fundamental information from the study of equilibrium adsorption isotherms and to investigate the adsorption mechanisms in the adsorption of MB, Cu2+, and Cd2+ onto raw date pits. The fit of two models, namely Langmuir and Freundlich models, to experimental data obtained from the adsorption isotherms was checked. The adsorption capacities of the raw date pits towards MB and both Cu2+ and Cd2+ ions obtained from Langmuir and Freundlich models were found to be 277.8, 35.9, and 39.5 mg g(-1), respectively. Surface functional groups on the raw date pits surface substantially influence the adsorption characteristics of MB, Cu2+, and Cd2+ onto the raw date pits. The Fourier transform infrared spectroscopy (FTIR) studies show clear differences in both absorbances and shapes of the bands and in their locations before and after solute adsorption. Two mechanisms were observed for MB adsorption, hydrogen bonding and electrostatic attraction, while other mechanisms were observed for Cu2+ and Cd2+. For Cu2+, binding two cellulose/lignin units together is the predominant mechanism. For Cd2+. the predominant mechanism is by binding itself using two hydroxyl groups in the cellulose/lignin unit. (C) 2009 Elsevier B.V. All rights reserved.