Amperometric determination of hydrogen peroxide in pickling baths for copper and copper alloys by flow injection analysis

The hydrogen peroxide is oxidized at + 1.5 V vs. SCE at a glassy carbon electrode of the wall-jet type. The samples are diluted about 100 times in a dispersion coil before entering the amperometric detector. The calibration curve is linear from 10^?4 to 1 M H₂O₂, when 5-μl samples are used. With 50-μl samples the detection limit decreases to 10^?6 M H₂O₂. Neither metal ions (Cu²⁺, Zn²⁺, Ni²⁺, Al³⁺) up to 0.5 M nor changes in the sulfuric acid concentration of the samples between 0.1 and 1 M interfere with the hydrogen peroxide determination. About 75 samples can be analyzed per hour.     

On the magnetic susceptibility of the liquid Pd1−x Si x alloy system at 1825 K

The isothermal magnetic susceptibility (x) of the completely miscible liquid Pd_1–x Si _x alloy system shows a rapid monotonous decrease withx from strong paramagnetism to weaklyx-dependent diamagnetism. The measured susceptibility isotherm at 1825 K is analysed within 0x1 by using a semiphenomenological method of decomposing the magnetic susceptibility into its constituent parts. Because of the empirical similarity between liquid and glassy metals this interpretation also provides assertions about the magnetism of glassy Pd_1–x Si _x aroundx=0.2.     

Lateral growth rates in laser CVD of microstructures

Lateral growth rates of Ni spots deposited on absorbing substrates by decomposition of Ni(CO)₄ with visible Kr⁺ laser light have been measured. The experimental data are consistent with the calculated temperature distributions. The mechanism of decomposition is thermal with an apparent chemical activation energy of 22±3 kcal/mole for the temperature range 350 KT500 K.     

Vacuum Ultraviolet Photolysis of Polyethylene,Polypropylene, and Polystyrene

Using infrared reflection absorption spectroscopy (IRRAS), quartz crystal microbalance (QMB) measurements, and X-ray photoelectron spectroscopy (XPS) in combination with chemical derivatization techniques the VUV photolysis of polyethylene (PE), polypropylene (PP), and polystyrene (PS) was investigated. A mass balance obtained from the quantification of the data was used to suggest reaction path ways. Although PE and PP behave similar, the mass loss is about 8 times higher in the case of PP. These differences originate from the higher disproportionation to recombination ratio for the branched polymer. Both polymers form double bonds and at extended treatment times they tend to crosslink. PS is rather stable due to the possibility of the energy dissipation by fluorescence.     

Zur Theorie des mechanischen und dielektrischen Relaxationsverhaltens von Makromolekülen in verdünnten Lösungen

Zusammenfassung Aufbauend auf den grundlegenden Untersuchungen vonKirkwood, Kirkwood undFuoss, Hammerle undKirkwood sowieErpenbeck undKirkwood werden die allgemeinen Grundgleichungen des mechanischen und dielektrischen Relaxationsverhaltens verdünnter und hochpolymerer L?sungen abgeleitet. Dabei wird unter Vernachl?ssigung von Valenz- und Deformationsschwingungen das ausN Atomen bestehende Makromolekül beliebiger chemischer Struktur und beliebigen Verzweigungsgrades durch ein Modell ersetzt, das ausK≤N Kugeln besteht, wobei die geometrische Struktur des Makromoleküls streng nachgebildet wird. Die zugeh?rigenK Kraftgleichungen werden zun?chst als eine Vektorgleichung im 3K-dimensionlen vollst?ndigen Konfigurationsraum gedeutet und anschlie?end unter Einführung eines geeigneten Koordinatensystems in denF-dimensionalen eigentlichen Konfigurationsraum projiziert, wobeiF die Zahl der Freiheitsgrade des Molekülmodells ist. Unter Verwendung der Kontinuit?tsgleichung gewinnt man daraus die Diffusionsgleichung, durch welche die Wahrscheinlichkeitsdichte im eigentlichen Konfigurationsraum bestimmt ist. Wird diese Differentialgleichung gel?st, so lassen sich die komplexe Viskosit?t und die komplexe Polarisation der hochpolymeren L?sung bestimmen. Im Rahmen der Rechnung wird gezeigt, da? die vonErpenbeck undKirkwood für das zugrundeliegende Koordinatensystem geforderten Orthogonalit?tsbedingungen nicht notwendig sind.     

Einwirkung von Schwefel und Ammoniak auf Propiophenon,n-Butyrophenon und i-Butyrophenon

Zusammenfassung Bei der Einwirkung von Schwefel und Ammoniak auf Propiophenon,n-Butyrophenon undi-Butyrophenon entstehen die entsprechenden Thiazoline-(3), deren saure Hydrolyse zu -Mercaptopropiophenon, -Mercapto-n-butyrophenon bzw. -Mercapto-i-butyrophenon führt. Die Dehydrierung dieser -Mercaptoketone mit Schwefel zu Di- bzw. Trisulfiden wird beschrieben. Die Kondensation der -Mercaptoketone mit Ammoniak und einer Oxokomponente führt zu neuen Thiazolinen-(3), von denen die in 2- und 5-Stellung monosubstituierten Vertreter sich mittels Schwefel zu Thiazolen dehydrieren lassen.

---

The interaction of sulfur and ammonia with propiophenone,n-butyrophenone andi-butyrophenone leads to the corresponding thiazolines-(3). On acid hydrolysis of the latter -mercaptopropiophenone, -mercapto-n-butyrophenone and -mercapto-i-butyrophenone respectively are formed. The dehydrogenation of these -mercaptoketones with sulfur to di- and trisulfides respectively is described. The condensation of the -mercaptoketones with ammonia and oxo-components yields new thiazolines-(3) of which the 2- and 5-monosubstituted compounds can be dehydrogenated to thiazols with elementary sulfur.

     

Goldstone mode singularities and equation of state of an isotropic magnet

Static properties of an isotropic magnet are calculated in the whole critical region including the magnetization curve. The method proposed is a resummation of renormalized perturbation theory without use of recursion relations. This is possible because only special diagrams or subdiagrams show infrared divergencies at the magnetization curve due to Goldstone modes. The arguments given are heavily based on Ward identities. The resulting perturbation theory is well behaved in the total critical region and exhibits explicitely the form of the Goldstone mode singularities at the magnetization curve. The equation of state is calculated including two-loop contribution. Resulting effective exponents are then correct in order in the whole critical region. In various limits agreement with known results is found. A one-loop calculation of the correlation functions is also given.     

Density fluctuations from elastic dipoles in glasses at low temperatures

The contribution of the population fluctuations of two-level systems in glasses to the dynamic structure factor is calculated using the concept of elastic dipoles. Describing the two-level systems by the tunneling model, with reasonable assumptions about the distribution of tunneling frequencies an essentially logarithmic decay in time of is obtained.     

Hyperfine structure of six low-lying fine structure levels of191Ir and193Ir and the191Δ s 193 hyperfine anomaly

The hyperfine interaction constantsA andB of six low-lying metastable fine structure states of the two iridium isotopes¹⁹¹Ir and¹⁹³Ir and the electronicg-factors of these levels have been measured using the atomic-beam magnetic-resonance method. From the values of the magnetic-dipole interaction constantsA, corrected for off-diagonal perturbations, we extracted the hyperfine anomaly of a pure 6s-electron state:¹⁹¹ Δ _s ¹⁹³ =0.64(7)%. Using nonrelativistic approximations for the effective radial parameters the nuclear electric-quadrupole moments were obtained:Q(¹⁹¹Ir) = 0.81(21)b,Q(¹⁹³Ir)=0.73(19)b     

Technetium-99 in Fucusand seawater samples in the Finnish coastal area of the Baltic Sea, 1999

Liquid discharges of ⁹⁹Tc from the Sellafield nuclear facilities increased largely in the mid 90"s. These releases are transported to the Nordic sea areas by the ocean currents. Results of the ⁹⁹Tc activities along the Norwegian coastal areas and in the North Sea have been reported but then again, the spreading of ⁹⁹Tc into Baltic Sea has not been studied thoroughly. Fucus vesiculosus and seawater samples were collected in the summer 1999 from the Finnish coastal areas for measuring ⁹⁹Tc in the Baltic Sea area. A modified analytical method for measuring ⁹⁹Tc in the environmental samples was developed at that time. The method based on extraction chromatography and liquid scintillation measurement of ⁹⁹Tc. The ⁹⁹Tc concentration in the Fucus vesiculosus in the Finnish coast of the Baltic Sea varied from 1.6 to 11.6 Bq/kg (dry weight) being highest at the most northern sampling sites. These values were considerable lower than those in the Danish and Norwegian coasts. The variation in the concentrations observed are probably due to biological factors. The ⁹⁹Tc concentration in the Baltic Sea water studied was below 0.2 Bq/m³.