Cavity ringdown spectra of ammonia at 10 parts in 10(9) by volume (ppbv) and higher concentrations were recorded by use of a 16-mW continuous-wave quantum-casacde distributed-feedback laser at 8.5 mum whose wavelength was continuously temperature tuned over 15 nm. A sensitivity (noise-equivalent absorbance) of 3.4x10(-9) cm(-1) Hz(-1/2) was achieved for ammonia in nitrogen at standard temperatu...

Abstract: Background and Aim: Tablets containing celecoxib tramadol hydrochloride that are sold under the brand name Seglentis® have given approval by “Food Drug Administration” (FDA) for treatment of adults suffering from acute pain. Simultaneous assessment in synthetic mixture was performed five new UV-spectrophotometric approaches. Materials Methods: The quantification proposed medication us...

Two-dimensional Fourier transform electronic spectra were recorded for the LH3 light harvesting complex. The spectra reveal the weak coupling between B800 molecules, the ultrafast dynamics within B820 and energy flow from B800 to B850.

Lycopene in tomatoes and tomato products is routinely determined by extraction into organic solvents and spectrophotometric quantification. The direct determination of lycopene, by measuring the color or other optical properties of a tomato homogenate, would be an attractive alternative. We have evaluated two instruments for this purpose. The color of tomatoes and tomato products is routinely d...

direct orthogonal signal correction(dosc) and savitzky-golay filters (sgf) were applied as preprocessing methods on the original and first derivative absorbance data. principle component regression (pcr), partial least squares (pls) and iterative target transformation factor analysis (ittfa), were used in spectrophotometric simultaneous determination of heavy divalent metal ions, lead, zinc,mer...

The relative absorption spectra of the bistable photopigment of single rhabdoms from the dorsal region of the retina of the honeybee drone were obtained using slices of retina fixed in glutaraldehyde; less accurate measurements on unfixed tissue gave difference spectra that were similar to those for fixed retinae. The method used was based on measurements of absorbance changes during saturating...

The secondary structure of human brain cytosolic and mitochondrial 'malic' enzymes purified to homogeneity has been investigated by Fourier-transform IR spectroscopy. The absorbance IR spectra of these two isoenzymes were slightly different, but calculated secondary-structure compositions were essentially similar (38% alpha-helix, 38-39% beta-sheet, 14% beta-turn and 9-10% random structure). Th...

Atmospheric analysis by open-path Fourier-transform infrared (OP/FT-IR) spectrometry has been possible for over two decades but has not been widely used because of the limitations of the software of commercial instruments. In this paper, we describe the current state-of-the-art of the hardware and software that constitutes a contemporary OP/FT-IR spectrometer. We then describe advances that hav...

Digital Fourier filtering is used to produce a temperature-insensitive univariate calibration model for measuring lysozyme in aqueous solutions. Absorbance spectra over the 5000-4000 cm-1 spectral range are collected for lysozyme standards maintained at 14 degrees C. These spectra are used to compute the calibration model while a set of spectra collected at temperatures ranging from 4 to 24 deg...

A technique for spectral searching with noisy data is described that improves the performance over contemporary approaches. Instead of simply calculating the correlation coefficient between the spectrum of an unknown and a series of reference spectra, greater weight is given to the more intense features in the reference spectra. The weight array, w, is given by |r|/{1 + d}, where the vector r r...