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...

the output of x-ray, especially in the field of required energy for diagnosing the disease is very low (in diagnosing lamps, it is less than 1%). in this kind of lamps the rest of the electrical energy is transformed to heat. this considerable amount of heat induces a myriad of too many limitations in choosing higher levels of radiation, particularly in specialized techniques. this process is t...

this paper presents a systematic study of the surface chemistry, porous texture and adsorptive characteristics of prepared new activated carbon using persian mesquite grain. several techniques and methodologies such as, proximate analysis, n2 adsorption–desorption isotherms, scanning electron microscope (sem), fourier transform infrared spectroscopy(ft-ir), x-ray diffraction (xrd), x-ray photoe...

three high-silica mordenite zeolites differing in sio440, ratio were prepared by direct synthesis without using any template. the products si02/a120, ratio is influenced by the starting gel composition. this ratio is increased upon ion-exchange with nh,cl and subsequent calcination to prepare protonic mordenite. the protonic mordenites with si02/a1203ra tios of 14.6,29.2 and 34.6 were character...

soil samples were collected from seven sites in and around the metropolitan area of mexicocity. the locations were chosen as possible sources of fugitive dusts which contribute to suspended particulate matter in the atmosphere of mexico city. x-ray fluorescence (xrf) was used to determine the concentrations of several major elements (si, k, ca, ti, mn, and fe), as well as of other trace element...