Search Results

You are looking at 1 - 10 of 585 items for :

  • "infrared spectroscopy" x
  • Refine by Access: All Content x
Clear All

Abstract  

The study of trans- and cis-1,2-cyclohexanediol by infrared spectroscopy was performed. The variation of the maximum frequency and of the bandwidth of the OH stretching vibration give evidence of the role played by hydrogen bonding in the solid and liquid phases of both isomers and allows to follow the phase transitions. A solid rotator phase is shown for the cis compound.

Restricted access

, F. , He , Y. , Wang , L. & Sun , G. ( 2011 ): Detection of organic acids and pH of fruit vinegars using near-infrared spectroscopy and multivariate calibration . Food Bioprocess Tech. , 4 , 1331 – 1340

Open access

microbial spoilage of meat by Fourier transform infrared spectroscopy and machine learning. Appl. environ. Microbiol. , 68 , 2822–2828. Goodacre R. Rapid and quantative detection

Restricted access

Sinelli, N., Casiraghi, E. & Downey, G. (2008): Studies on proofing of yeasted bread dough using near- and mid-infrared spectroscopy. J. agric. Fd Chem. , 56 , 922–931. Downey G

Restricted access

near-infrared spectroscopy (NIRS), is able to non-invasively provide information about these changes in oxygenation and hemodynamics in muscle tissue based on the oxygen-dependent characteristics of near-infrared light. NIRS has been utilized to

Open access

Abstract  

In this paper the structural characterization of terfenadine crystallized from ethanol-water, ethanol and methanol is performed by infrared spectroscopy. The OH stretching vibration, composed of three markedly overlapped bands, is analyzed by peak fitting. The assignment of the hydrogen bonds was conducted making use of band parameters, spectroscopic data for CCl4 solutions, and molecular dynamics calculations from dimeric systems. Terfenadine just precipitated from solvents is never in the highest crystalline state. This state is reached when the samples are heated at a temperature above 100C. Some amorphous solid is coprecipitated with the crystalline phase, particularly in methanol.

Restricted access

Abstract  

This paper presents and interprets photoacoustic (PA) infrared spectra and four different thermophysical properties (thermal conductivity, thermal diffusivity, volumetric specific heat and thermal effusivity) for four sets of hydrocarbon cokes. A total of 12 samples, with varying histories, were analyzed. These cokes are a by-product of the upgrading of bitumen to Syncrude Sweet Blend (a blend of hydrotreated components), and were obtained from several locations in the thermal cokers operated by Syncrude Canada Ltd. in Fort McMurray, Alberta, Canada. PA infrared spectroscopy provides detailed information on the amount and type of residual aromatic hydrocarbons in cokes; aliphatic hydrocarbons are sometimes detected in smaller quantities. Three of the thermophysical properties (thermal conductivity, diffusivity and effusivity) display systematic differences among the cokes. On the other hand, volumetric specific heat hardly varies, a phenomenon that accounts for the observed proportionality between thermal diffusivity and conductivity. Analogous relationships exist between thermal effusivity and both thermal conductivity and thermal diffusivity for these cokes. The magnitudes of these three thermophysical properties tend to increase as aromatics contents, determined by PA spectroscopy, decrease.

Restricted access

Abstract  

Although thermogravimetric analysis (TG) has become an indispensable tool for the analysis and characterization of materials, its scope is limited as no information is obtained about the qualitative aspects of the evolved gases during the thermal decomposition. For processes involving mass loss, a powerful technique to provide this missing information is Fourier transform infrared spectroscopy (FT-IR) in combination with TG. It supplies a comprehensive understanding of thermal events in a reliable and meaningful way as data are obtained from a single sample under the same conditions. The coupling TG/FT-IR is used in fuel analysis for the identification of residual volatiles, to determine their sequence of release and to resolve thermogravimetric curves. In this work, the usefulness of TG/FT-IR for characterizing middle distillate fuel residues is illustrated with some typical examples of recent application. A Bio-Rad FTS 25 FT-IR spectrometer coupled with a TA Instruments TGA 2950 thermogravimetric analyzer was used for data aquisition. The results obtained demonstrate the utility of this combined technique in determining the decomposition pathway of tarry materials at various stages of pyrolysis, thereby allowing new insights into the complex thermal behaviour of hydrocarbon residual systems.

Restricted access

Abstract  

The paper presents the applicability of oxyreactive thermal analysis (OTA) for the investigation of different kinds of resins both natural (recent and fossil) and synthetic. For comparative reasons and a more precise interpretation, along with OTA infrared spectroscopy was used as a method commonly applied for the investigation of fossil resins. The results obtained prove that the OTA method may be very useful for diversification of different kinds of resins. The parameter most valuable for the preliminary characteristics of resins and the evaluation of their transformation was found to be the mass loss recorded on TG curves in three definite temperature ranges.

Restricted access
Progress in Agricultural Engineering Sciences
Authors: Marina Vranić, Mladen Knežević, Zsolt Seregély, Krešimir Bošnjak, Josip Leto, and Goran Perčulija

Blanco, M., Coello, J., Iturriaga, H., Maspoch, S., Gonzalez, R. (1998) Determination of water in lubricating oils by mid- and near-infrared spectroscopy. Microchim. Acta 128: 235. Determination of water in lubricating oils by

Restricted access