The Knoevenagel condensation of aromatic aldehydes with barbituric acid, dimedone and malononitrile occurred in the presence of BF3/nano-γ-Al2O3 at room temperature in ethanol. This catalyst is characterized by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and energy-disper...

A method is presented for computing an orthonormal set of eigenvectors for the discrete Fourier transform (DFT). The technique is based on a detailed analysis of the eigenstructure of a special matrix which commutes with the DFT. It is also shown how fractional powers of the DFT can be efficiently computed, and possible applications to multiplexing and transform coding are suggested. T

The quaternion Fourier transform (QFT), which is a nontrivial generalization of the real and complex Fourier transform (FT) using quaternion algebra has been of interest to researchers for some years (see e.g. [3, 5]). It was found that many FT properties still hold but others have to be modified. Based on the (right-sided) QFT, one can extend the classical wavelet transform (WT) to quaternion ...

caco3 nanoparticles have been synthesized via heat-treatment of a new precursor and solid state reaction. effect of calcinations temperature and quantity of surfactant on particle size has been investigated. the products were characterized by x-ray diffraction (xrd), scanning electron microscopy (sem), transmission electron microscopy (tem) and fourier transform infrared (ft–ir) spectroscopy.

ruthenium dioxide nanoparticles (ruo2 ) with an average particle size of 50 nm are readily synthesized from rucl3.xh2o via the precipitation process in the presence of in-situ sodium octanoate as anionic surfactant. the phase composition, morphology, lattice parameters and size of nanoparticles in these products are characterized by fourier transform infrared spectroscopy (ft-ir), x-ray diffrac...

Infrared spectroscopy is nowadays one of the most important analytical techniques available to scientists. One of the greatest advantages of the infrared spectroscopy is that virtually any sample in any state may be analyzed. For example, liquids, solutions, pastes, powders, films, fibres, gases and surfaces can all be examined with a judicious choice of sampling technique. The review by Annett...

A femtosecond mode-locked laser is used for what is believed to be the first time as a broadband infrared source for high-resolution Fourier transform absorption spectroscopy. A demonstration is made with a Cr(4+):YAG laser. The entire nu(1)+nu(3) vibration-rotation band region of acetylene, observed after passing through a single-pass 80-cm-long cell, is simultaneously recorded between 1480 an...

The detection of weak absorption changes induced by an external excitation is often hindered by intense background absorptions as well as by noise. Modulation spectroscopy is an adequate tool to be applied in such a case, provided the system may be periodically stimulated, leading to a periodic reversible or pseudoreversible response. In modulated excitation ~ME! Fourier transform infrared spec...

Thirty-nine freeze-dried tissue samples from 17 lymphoid tumors (nine malignant non-Hodgkin's lymphomas) were studied by Fourier transform infrared (FTIR) spectroscopy. The absorbance ratio A1121/A1020 increased, along with the emergence of an absorbance pulse at 1121 cm-1, with increasing clinicopathological grade of malignant lymphoma. An increasing A1121/A1020 ratio from benign to malignant ...

al2o3-sio2 diphasic gel was synthesized by sol gel route from aluminium nitrate and silicic acid following aqueous phase colloidal interaction. the precursor gel powder was thoroughly characterized by chemical analysis, measurement of surface area and bulk density measurement. the gel powder was further characterized by thermogravimetry, xrd diffraction study of the heat treated samples and sca...