Beim Vergleich verschiedener jodometrischer Verfahren zur Bestimmung der Peroxydzahl

Ohne Zusammenfassung     

Eine Methode zur colorimetrischen Bestimmung von prim?ren Aminen in aliphatischen Aminacetaten und Aminen Ton hohem Molgewicht

Ohne Zusammenfassung     

Dynamical reduction in multidimensional cosmological models

We present conditions under which there occurs a dynamical dimensional reduction of cosmological models in the form of Bianchi I×(N-3)-dimensional torus filled with matter of the ideal fluid type.     

Zum Nachweis von technischem Invertzucker in Honig

Ohne Zusammenfassung     

The influence of molecular rotational diffusion on Gaussian pulse-induced third-order electric polarisation in liquids

Time evolution curves of the changes in nonlinear electric polarisation induced by Gaussian pulses are calculated theoretically with the Smoluchowski-Debye molecular rotational diffusion equation not including the influence of the moment of inertia of the molecules or their interactions. Graphs show the dynamics of the third-order electric polarisation versus the Gaussian pulse width and the parameter R, defining the balance between the dipolar and anisotropically polarisable properties of the molecules.     

Intrinsic hydration of monopositive uranyl hydroxide,nitrate, and acetate cations

The intrinsic hydration of three monopositive uranyl-anion complexes (UO(2)A)(+) (where A = acetate, nitrate, or hydroxide) was investigated using ion-trap mass spectrometry (IT-MS). The relative rates for the formation of the monohydrates [(UO(2)A)(H(2)O)](+), with respect to the anion, followed the trend: Acetate > or = nitrate > hydroxide. This finding was rationalized in terms of the donation of electron density by the strongly basic OH(-) to the uranyl metal center, thereby reducing the Lewis acidity of U and its propensity to react with incoming nucleophiles, viz., H(2)O. An alternative explanation is that the more complex acetate and nitrate anions provide increased degrees of freedom that could accommodate excess energy from the hydration reaction. The monohydrates also reacted with water, forming dihydrates and then trihydrates. The rates for formation of the nitrate and acetate dihydrates [(UO(2)A)(H(2)O)(2)](+) were very similar to the rates for formation of the monohydrates; the presence of the first H(2)O ligand had no influence on the addition of the second. In contrast, formation of the [(UO(2)OH)(H(2)O)(2)](+) was nearly three times faster than the formation of the monohydrate.     

Stable ammonium bisulfate clusters in the atmosphere

Liquid drop model based equilibrium thermodynamics predicts that in the presence of even small ammonia concentrations practically all the atmospheric sulfuric acid molecules are bound to tiny, stable ammonium-bisulfate clusters. Hitherto sulfuric acid has been believed to form hydrates with water. Thermodynamic theory predicts correctly the hydrate formation observed experimentally. Results from ab initio computer simulations contradict the thermodynamic results and also the experimental findings for cluster formation in both sulfuric acid-water and ammonia-sulfuric acid-water mixtures.     

High-efficiency broadband diffractive elements based on polarization gratings

A method is introduced for designing paraxial-domain diffractive elements working over a broad frequency range. The method is based on space-variant manipulation of the state of polarization by form-birefringent binary diffractive structures. It is shown that any scalar phase transmission function can be realized by use of such polarization-modulating structures and that at least in some cases it is even possible to exceed the scalar paraxial-domain upper bounds of diffraction efficiency over a broad frequency band.     

High-power femtosecond fiber-feedback optical parametric oscillator based on periodically poled stoichiometric LiTaO3

We demonstrate a synchronously pumped high-gain optical parametric oscillator with feedback through a fiber, using a passively mode-locked Yb:YAG thin-disk laser as a pump source. We obtain as much as 19-W average signal power at a wavelength of 1.45 microm in 840-fs pulses and 7.8 W of idler power at 3.57 microm. The repetition rate of the pulses is 56 MHz, and the transverse beam quality of the generated signal is M2 < 1.6.