A comparison of different dissolution techniques for determination of uranium in soil samples was made. Conventional wet dissolution with mixtures of HNO3, HClO4 and HF acids, microwave dissolution ...using HNO3 and HF, and alkaline fusion with Na2CO3 and Na2O2 were evaluated. For testing the effectiveness of the dissolution procedures, two reference materials and six soil samples from the surroundings of a former uranium mine were investigated. It was observed that the content of uranium in the residues determined by INAA represents a significant contribution to its total concentration in the sample, especially in the case of microwave dissolution.
•Various most often used dissolution techniques for soil samples were investigated.•Conventional wet ashing, microwave dissolution and alkaline fusion were tested.•The residues obtained after dissolution were tested for uranium content.•Instrumental neutron activation analysis was used for uranium determination.•The results showed that the tested dissolution techniques must be improved.
Four different electrolyte solutions were used in the electrodeposition of americium and their influences on the quality of the thin layer of deposited americium isotopes in combination with three ...different cathode disc materials were investigated. The relations between alpha spectral resolution and disc surface properties were established.
► Compared alpha spectra of americium radioisotopes obtained by electrodeposition. ► Various cathode materials and electrolyte solutions were used. ► Homogeneity and peak area resolution were investigated. ► Electron microscope images show surface structure of electrodeposited material.
The main aim of this work was to study the influence of the NiSO4 precursor and the annealing temperature on the electrochemical stability and electrochromic response of dip-coated Ni-oxide films. ...Nickel hydroxide was precipitated from the precursor solution using lithium hydroxide and the slurry was then peptized with acetic acid. Dynamic thermogravimetric measurements made on thin films showed that the decomposition and the formation of Ni-oxide phase differed for powders and films. The results showed that the films annealed at 270 deg C (at which the acetate groups decomposed) consisted of cubic (space group Fm3m) NiO grains (2-3 nm, TEM measurements) having monodentately coordinated sulfate groups (IR spectrum). Electrochemical and in situ UV-visible spectroelectrochemical studies of the Ni-oxide films (NiSO4 precursor, 270 deg C) revealed that the photopic transmittance in the colored state (3rd cycle) is 66% and 89% in the bleached state. Cycling (100th cycle) reduced the transmittance of the films in the colored state to 50%, while the bleached films retained their high transmittance (89%). The coloration efficiency of the films was 35-41 cm2 C-1 depending on the number of cycles. The evolution of the Ni3+ -O stretching vibration (transversal optical mode) of the films in the charged state was followed by the help of ex situ infrared spectroelectrochemical measurements.
Convective interaction media (CIM; BIA Separations) monoliths are attractive stationary phases for use in affinity chromatography because they enable fast affinity binding, which is a consequence of ...convectively enhanced mass transport. This work focuses on the development of novel CIM hydrazide (HZ) monoliths for the oriented immobilization of antibodies. Adipic acid dihydrazide (AADH) was covalently bound to CIM epoxy monoliths to gain hydrazide groups on the monolith surface. Two different antibodies were afterwards immobilized to hydrazide functionalized monolithic columns and prepared columns were tested for their selectivity. One column was further tested for the dynamic binding capacity.
Ni-oxide films prepared using the sol-gel route and dip-coating method have been investigated by X-ray diffraction, scanning electron microscopy, FT-IR spectroscopy, cyclic voltammetry and in situ ...UVVIS spectroelectrochemical methods.
The sols were prepared from a nickel sulphate hexahydrate precursor with formamide and polyvinylalcohol added to improve the abrasive resistance of films and to increase the yield from dip-coating deposition method (100–120 μm per dipping cycle). The films consisted of 40% NiO crystalline phase with an average grain size of 10 to 30 Å. The crystallites were incorporated into the amorphous phase which was found to resemble the α(II)-Ni(OH)
2 phase. A pronounced electrochromic effect (
ΔT ≈ 60%) was found by cycling the films in a 0.1 M LiOH electrolyte. This produced a maximum colouration efficiency (
λ = 450 nm) of 35–40 cm
2 C
−1. Longitudinal optical (LO) mode of films potentially cycled up to 200 times have been detected by near-grazing incidence angle (NGIA) FT-IR reflection-absorption spectroscopy. The results revealed that the as-deposited films are progressively transformed to the β(II)-Ni(OH)
2 phase which is then converted to the β(III)-NiOOH phase during further potential cycling. The influence of foreign ions (SO
2−
4, CO
2−
3, OH
−) on the development of persistent electrochromism and stability of films was established and discussed in detail.
Thin films of Ce/Cu mixed oxide with molar ratios of 1 and 2 were prepared from inorganic precursors using the sol–gel route. Various electrochemical and spectroscopic techniques were used for ...characterization of the films and investigation of their optical and electrochemical properties. It was found that the redox behaviour significantly depends on the Ce/Cu ratio and on the concentration of Li
+ ions. Slow kinetics of the charge transfer reactions was evident from cyclic voltammetry measurements of both types of films only at low scan rates (<20
mV/s). Measurement of X-ray absorption fine structure (XAFS) indicated that the local structure of Ce and Cu ions is not affected by the Ce/Cu molar ratio.
A carbon fiber microelectrode (CFME) was used for characterization of the nanoparticle catalysts as an alternative to the well-established rotating disk electrode (RDE) method. We found that the ...novel CFME method yielded comparable results to the RDE method when investigating the adsorption/desorption processes as well the specific activity for reactions such as the oxygen reduction reaction. Its major advantage over the RDE method is a fast sample preparation and rapid measurement, reducing significantly the time of a single sample characterization from 2−3 h to a favorable 5−10 min.
The aim of the present work was to provide a better understanding of the biocompatibility of Co-based alloys in the physiological environment. Co-based alloys are widely used in orthopaedics for the ...manufacture of prosthetic devices. Two alloys, Co-Cr-Mo and Co-Ni-Cr-Mo, and their individual metal components were studied in simulated physiological solution at 37 deg C, with and without the addition of two complexing agents, EDTA and citrate, in the concentration range from 0.1 to 50 mm. The processes were studied using electrochemical techniques: cyclic voltammetry, anodic potentiodynamic measurements, linear polarization and electrochemical impedance spectroscopy. The results are discussed in the context of the dependence of the passivation behaviour of the two alloys on their composition. Both alloys are shown to passivate very well in simulated physiological solution. The effect of complexing agents is more evident on Co-Ni-Cr-Mo than on Co-Cr-Mo alloy. This appears to be related to the presence of Ni.
The electrochemical behaviour of Cu-xZn alloys and of Cu and Zn metals was studied by cyclic voltammetry and chronopotentiometry in borate buffer, pH = 9.2, with and without the addition of chloride ...ions in the range from 0.01 m to 1 m. In general, the shape of voltammograms of four Cu-xZn alloys with 10 - 40 wt.% of zinc resembles that of copper more than that of zinc. With increasing zinc content several characteristics of zinc are observed. In borate buffer containing chloride anions, Cu-xZn alloys are susceptible to pitting corrosion. The breakdown potential, Eb, at which the current density in the passive region starts to increase abruptly, becomes more negative with increasing zinc content in the alloy. The general relationship Eb = a + b log cNaCl held in all cases, with constants a and b, however, being dependent on the zinc content of the alloy and on the chloride concentration. The corrosion resistance of Cu-xZn alloys was less than that of copper metal but significantly greater than that of zinc.
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