Thermal and structural study of nanocrystalline Fe(Co)NiZrB alloys prepared by mechanical alloying

Three nanocrystalline alloys, Fe_75−x Co _x (Ni₇₀Zr₃₀)₁₅B₁₀ (x = 0, 10, and 20), were synthesized from elemental powders in a planetary high-energy ball mill. Their microstructure, magnetic properties, and thermal stability were characterized by X-ray diffraction, transmission M?ssbauer spectroscopy, transmission electron microscopy, scanning electron microscopy, induction coupled plasma, vibrating sample magnetometry, and differential scanning calorimetry. After 80 h of milling, the nanocrystallites size of alloys is in the range 6–10 ± 1 nm. The lattice parameter decreases when increasing (decreasing) milling time (Fe content). Furthermore, the thermal stability of the nanocrystalline phase increases when increasing Co concentration. The activation energy of the main crystallization process, between 275 ± 8 and 311 ± 10 kJ mol⁻¹, is associated with grain growth. Slight contamination from milling tools and milling atmosphere was detected. Minor differences were detected after M?ssbauer analysis.     

Zn(II) adsorption from synthetic solution and kaolin wastewater onto vermicompost

The adsorption of Zn(II) from both synthetic solution and kaolin industry wastewater by cattle manure vermicompost was studied. The adsorption process was dependent on the various operating variables, viz., solution pH, particle size of the vermicompost, mass of vermicompost/volume of the Zn(II) solution ratio, contact time and temperature. The optimum conditions for Zn adsorption were pH 6.0, particle size of < or = 250 microm, 1 g per 10 mL adsorbent dose, contact time of 4h and temperature of 25 degrees C. Langmuir and Freundlich adsorption isotherms fit well in the experimental data and their constants were evaluated, with R(2) values from 0.95 to 0.99. In synthetic solution, the maximum adsorption capacity of the vermicompost for Zn(2+) ions was 20.48 mg g(-1) at 25 degrees C when the vermicompost dose was 1 g 10 mL(-1) and the initial adjusted pH was 2. The batch adsorption studies of Zn(II) on vermicompost using kaolin wastewater have shown the maximum adsorption capacity was 2.49 mg g(-1) at pH 2 (natural pH of the wastewater). The small values of the constant related to the energy of adsorption (from 0.07 to 0.163 L mg(-1)) indicated that Zn(2+) ions were binded strongly to vermicompost. The values of the separation factor, R(L), which has been used to predict affinity between adsorbate and adsorbent were between 0 and 1, indicating that sorption was very favorable for Zn(II) in synthetic solution and kaolin wastewater. The thermodynamic parameter, the Gibbs free energy, was calculated for each system and the negative values obtained confirm that the adsorption processes are spontaneous. The DeltaG degrees values were -19.656 kJ mol(-1) and -16.849 kJ mol(-1) for Zn(II) adsorption on vermicompost in synthetic solution at pH 6 and 2, respectively, and -13.275 kJ mol(-1) in kaolin wastewater at pH 2.     

Color space transformations for digital photography exploiting information about the illuminant estimation process

The color reproduction accuracy is a key factor to the overall perceived image quality in digital photography. In this framework, both the illuminant estimation process and the color correction matrix concur in the formation of the overall perceived image quality. To the best of our knowledge, the two processes have always been studied separately, thus ignoring the interactions between them. We investigate here these interactions, showing how the color correction transform amplifies the illuminant estimation errors. We demonstrate that incorporating knowledge about the illuminant estimation behavior in the optimization of the color correction matrix makes it possible to alleviate the error amplification. Different strategies to improve color accuracy under both perfect and imperfect white point estimations are investigated, and the experimental results obtained with a digital camera simulator are reported.