A Polarographic Study of Chlorogenic Acid and Its Interaction with Some Heavy Metal Ions

The behavior of chlorogenic acid (CGA) and its interaction with Hg(II), Pb(II), Cu(II), Cd(II) and Zn(II) has been studied using direct current (DC) and differential‐pulse polarography (DPP). Adsorptive and kinetic/catalytic anodic waves of CGA have been detected at ?0.02 and ?0.18 V vs. SCE, respectively; Hg(I)‐CGA surface disproportionation has been assumed. Reduction of Hg(II)‐ions, added in the buffered solution of CGA (pH 7.5), occurs rather than complexation, while the complex forming ability of CGA towards Pb(II) and Cu(II) has been observed. Stoichiometry 1 : 1 for Pb(II)‐CGA, and 1 : 1 and 1 : 2 for Cu(II)‐CGA has been established applying Job’s method of continuous variation on DPP data. UV‐vis spectrophotometric measurements additionally confirmed the existence and stoichiometry of Cu(II) complexes.     

Coulomb break-up of the deuteron by the positive muon

The μ⁺d → μ⁺pn process is described in the framework of three-body scattering theory which includes two charged particles. Explicit formulas for the break-up amplitude are given, and muon spectra are calculated in a simple approximation. n-p off-energy-shell effects are investigated.     

Daubechies compactly supported wavelets with minimal heisenberg boxes

The centers and radii of orthonormal scaling functions and wavelets are found in time and frequency domains using a two-scale relation. All compactly supported orthogonal wavelets with support on the interval [0, 3] fail to have radii in the frequency domain. On the other hand, a Daubechies wavelet with support on the interval [0, 3] has optimal resolution in the frequency domain. Vilnius University, Naugarduko 24, 2006 Vilnius, Lithuania. Published in Lietuvos Matematikos Rinkinys, Vol. 35, No. 8 pp. 432–455, October–December, 1995.     

Linear preserver problems and algebraic groups

Supported by University of Waterloo Grant and the Alexander von Humboldt Foundation     

Local functional measure for some theories with singular Lagrangians

Local functional measure is calculated from the requirement of cancellation of the leading divergences at one loop level for gravity, supergravity and gravity-Yang-Mills theory.     

Preparation of carrier-free radionuclides from cyclotron targets by continuous electrophoresis,I

Continuous electrophoretic separation of the components of the manganese, iron, copper and silver cyclotron targets bombarded with deuterons is described. The rates of separation were: managanese target, 4.4 mg Mn/hr; iron target, 1.5 mg Fe/hr; copper target, 1.7 mg Cu/hr; and silver target, 6.7 mg Ag/hr. The radionuclides were separated in carrier-free form and were of high radiochemical purity. The results are represented by radioautographs of the continuous electrophoretic processes, and by diagrams showing the distribution of the target material and of radioactivity along the collecting glasses. The radiochemical purity of the separated radionuclides was checked by the gamma spectra, by estimation of the beta-energies, and by evaluation of the decay curves.     

Oxidation of phenol on RuO2–TiO2/Ti anodes

The oxidation of phenol on the RuO₂–TiO₂/Ti electrode has been studied by cyclic voltammetry, polarization measurements, electrochemical impedance spectroscopy and potentiostatic transients in H₂SO₄ and NaCl aqueous solutions. A reaction path with polymerization as the main reaction and side reactions after the initial step, similar to the reaction path on other electrode materials, is suggested. The formation of a phenoxy radical in a diffusion-controlled irreversible process is the initial step. The polymerization of phenoxy radicals leads to the formation of porous polyoxyphenylene film, strongly adherent to the electrode surface. The cyclic voltammetry measurements indicate side products, which could be, according to the literature, of quinone-like structure. Polyoxyphenylene film inhibits further oxidation of phenol, although complete electrode passivation was not observed. The presence of polyoxyphenylene film does not influence the pseudocapacitive behaviour of the electrode to a great extent, since the polyoxyphenylene film covers dominantly the coating surface, while active sites placed within coating cracks remain uncovered. The film seems to be permeable for hydrogen ions and water molecules.     

Kinetics and mechanism of thermal decomposition of lead carbonate

Results are given on the kinetics and mechanism of the processes in the thermal decomposition of lead carbonate with the application of TG and DTA experimental investigation methods.The following mechanism was established: 3 PbCO₃=2 PbO.PbCO₃+2 CO₂ (1) 2 PbO.PbCO₃=3 PbO+CO₂ (2) PbO — melting (3)The following activation energy values were determined with TG methods for processes (1) and (2): 118.2 and 235.2 kJ/mole, respectively; and with DTA methods for processes (1), (2) and (3): 113.9, 246.6 and 294.9 kJ/mole, respectively.

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Zusammenfassung Die an Hand der TG- und DTA-Untersuchungen erhaltenen Ergebnisse über Kinetik und Mechanismus der bei der thermischen Zersetzung von Bleicarbonat auftretenden VorgÄnge werden beschrieben.Die folgenden Mechanismen des Vorganges wurden festgestellt: 3 PbCO₃=2 PbO.PbCO₃ + 2 CO₂ (1) 2 PbO.PbCO₃=3 PbO + CO₂ (2) PbO — Schmelzen (3)Die folgenden Werte der Aktivierungsenergie wurden durch TG-Versuche für die VorgÄnge (1) und (2) bestimmt: 118.2, bzw. 235.2 kJ/Mol, und durch DTA-Messungen für die VorgÄnge (1), (2) und (3): 113.9, 246.6, bzw. 294.9 kJ/Mol.

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Résumé La cinétique et le mécanisme des réactions qui se déroulent lors de la décomposition thermique du carbonate de plomb ont été étudiés par TG et ATD. Les mécanismes suivants ont été établis: 3 PbCO₃=2 PbO.PbCO₃+2 CO₂ (1) 2 PbO.PbCO₃=3 PbO + CO₂ (2) PbO — fusion (3)Pour les réactions (1) et (2), les valeurs de 118.2 et 235.2 kJ · mol^–1 ont été trouvées à partir des résultats TG et pour les réactions (1), (2) et (3) l'ATD a fourni respectivement 113.9, 246.6 et 294.9 kJ · mol^–1.

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, . : 3 ₃=2 PbO.PbCO₃+2 ₂ (1) 2 PbO.PbCO₃=3 +O₂ (2) — (3) (1) (2), 118.2 235.2 /. (1), (2) (3) : 113.9; 246.6 294.9 /.

     

Transition Metal Complexes with Pyrazole-based Ligands. Part 8. Characterization and thermal decomposition of zinc(II) complexes with di- and trisubstituted pyrazoles

We report the synthesis and the characterization (elemental analysis, FT-IR spectroscopy, thermal methods and molar conductivity measurements) of the mixed complexes of zinc with acetate and 3-amino-5-methylpyrazole, HL ¹, [Zn(OAc)₂(HL¹)₂], or 3-amino-5-phenylpyrazole, HL ² [Zn(OAc)₂(HL²)₂], or 4-acetyl-3-amino-5-methylpyrazole, HL ³, [Zn(OAc)(L³)(HL³)]₂, with isothiocyanate and HL ² [Zn(SCN)₂(HL²)₂], or HL ³ [Zn(SCN)₂(HL³)₂], and with nitrate, isothiocyanate and 3,5-dimethyl-1-carboxamidinepyrazole, HL ⁴ [Zn(NO₃)(NCS)(HL⁴)₂]. The thermal decomposition of the complexes is generally continuous resulting zinc oxide as end product,except [Zn(OAc)(L³)(HL³)]₂ in which case a well-defined intermediate was observed between 570–620 K. On the basis of the IR spectra and elemental analysis data of the intermediate a decomposition scheme is proposed. This revised version was published online in August 2006 with corrections to the Cover Date.