JPC – Journal of Planar Chromatography – Modern TLC - TLC and HPLC have been used for preliminary evaluation of the phenolic acids occurring in the leaves, inflorescences, and rhizomes... 相似文献
A short-term aerobic stabilization of digested waste in the final methane phase was studied. The effect of aeration rate on
the reduction of leachate parameters and on the rate of CO2 production and O2 assimilation was investigated. Experimental simulation of aerobic landfill stabilization was carried out using lysimeters.
When testing the effect of aeration rate on the reduction of leachate indices (BOD5, COD, N-NH4+), it was reported that the most significant reduction was obtained at the highest rate of aeration and the smallest reduction
of leachate indices was attained not at the lowest but at medium aeration rates. Both the rate of CO2 production and the O2 assimilation reached their highest values in the lysimeters aerated at a high rate of aeration. The proposed mathematical
model which consists of a system of five differential equations describing CO2 production, O2 assimilation and the changes of organic carbon content in the leachate correspond well with the experimental data. 相似文献
Dialkyl [2-hydroxy-5-(phenylazo)benzyl]phosphonates were prepared by a convenient procedure in good yield from Mannich base and trialkyl phosphite in benzene with the elimination of ammonium or morpholinium cation. 2-[(Dialkylamino)methyl]-4-(phenylazo)phenol methiodide is a new reagent in the Michaelis-Arbuzov reaction. 相似文献
The synthesis and characterization of a new tetra (triphenylphosphonium) p-tert-butylcalix[4]arene 2 is presented. Its interactions with anions were studied by 1H and 31P NMR and UV absorption spectrophotometry, showing the biggest interaction with ClO4? , I? and SCN? . Anion selectivity in ion-selective PVC-membrane electrodes (ISEs) plasticized with o-NPOE containing ionophore 2 was also investigated. Compound 2 shows a potentiometric response for various anions with the following selectivity pattern: ClO4? > SCN? > I? > Cr2O72 ? > NO3? > Br? > Cl? . 相似文献
Ternary CuO-ZrO2-Al2O3 catalysts promoted by palladium or gold were prepared and tested in CO hydrogenation reaction at 260°C under elevated pressure (4.8 MPa). The promotion effect of palladium or gold addition on the physicochemical and catalytical properties of CuO-ZrO2-Al2O3 catalysts in methanol synthesis (MS) was studied. The catalysts were characterized by BET, XRD, TPR-H2, TPD-NH3 methods. The BET results showed that the ternary system CuO-ZrO2-Al2O3 had the largest specific surface area, cumulative pore volume and average pore size in comparison with the promoted catalysts. The yield of methanol can be given through the following sequence: 5%Pd/CuO-ZrO2-Al2O3 > CuO-ZrO2-Al2O3 > 2%Au/CuO-ZrO2-Al2O3. We also found that the presence of gold or palladium on catalyst surface has strong influence on the reaction selectivity. The high selectivity of gold doped ternary catalyst is explained by the gold-oxide interface sites created on the catalyst surface and the acidity of those systems. The higher selectivity to methanol in the case of the palladium catalyst is explained by the spillover effect between Pd and CuO. 相似文献
We present a new method to measure 1/f noise in Josephson quantum bits (qubits) that yields low-frequency spectra below 1 Hz. A comparison of the noise taken at positive and negative bias of a phase qubit shows the dominant noise source to be flux noise and not junction critical-current noise, with a magnitude similar to that measured previously in other systems. Theoretical calculations show that the level of flux noise is not compatible with the standard model of noise from two-level state defects in the surface oxides of the films. 相似文献
The preparation of 5,7-disubstituted imidazo[5,1-f][1,2,4]triazin-4-amines, exemplified by 5-[3-(benzyloxy)phenyl]-7-cyclobutylimidazo[5,1-f][1,2,4]triazin-4-amine, was developed through a linear and three convergent synthetic strategies, with the latter providing the greatest flexibility for diversification at the 5-position at the last step of the synthesis. 相似文献
Rectangular arrays of pyramidal recesses coated by silver film are investigated by means of polarization‐resolved nonlinear microscopy at 900 nm fundamental wavelength, demonstrating strong dependence of the dipole‐allowed SHG upon the lattice parameters. The plasmonic band gap causes nearly complete SHG suppression in arrays of 650 nm periodicity, whereas a sharp resonance at 550 nm periodicity is observed due to excitation of band edge Bloch states at fundamental frequency, accompanied by symmetry‐constrained interactions with similar modes at the second‐harmonic frequency. Additionally, coupling with modes at the bottom side of the silver film may lead to extraordinary optical transmission, opening a channel for SHG from the highly nonlinear GaAs substrate. Changing the lattice geometry enables SHG intensity modulation over three orders of magnitude, while the effective nonlinear anisotropy can be continuously switched between the two lattice directions, reaching values as high as ±0.96.