Redox Treatment Effects on the Magnetic Properties of Copper Chromite

Magnetic susceptibility and low-temperature neutron diffraction measurements were performed to study the effect of redox treatments of copper chromite on its magnetic properties. When copper chromite is subjected to reduction at 453-643 K, magnetic ordering with T _c = 130 K disappears. Reoxidation does not completely restore the magnetic properties. The changes in the magnetic properties of copper chromite induced by sequential reduction and reoxidation correlate with its structural changes.     

5H-Thiazolo [3,2-b]- and 2H-Thiazolo [2,3-c]-as-triazines

Derivatives of the 5H-thiazolo[3,2-b]- and 2H-thiazolo[2,3-c]-as-triazine systems were synthesized via condensation of tetrahydro-I-methyl-as-triazine-3(2H)-thione with ethylene dibromide and ethyl bromoacetate, respectively. An hypothesis is given for the formation of the [3,2-b] system in one of these reactions and the [2,3-c] system in the other. Structure proof was accomplished by an unequivocal synthesis of one of the [2,3-c] derivatives.     

An analogue of Fekete’s lemma for subadditive functions on cancellative amenable semigroups

We prove an analogue of Fekete’s lemma for subadditive right-subinvariant functions defined on the finite subsets of a cancellative left-amenable semigroup. This extends results previously obtained in the case of amenable groups by E. Lindenstrauss and B. Weiss and by M. Gromov.     

Fe- and Al-doped apatite-type lanthanum silicates: Structure and property characterization

For the first time the local structure of Al- and Fe-doped apatite-type lanthanum silicates (ATLS) of different stoichiometries was systematically studied by using IR spectroscopy. In addition to previous ²⁹Si MAS NMR study, data obtained confirm the possibility of [SiO₄] group interaction in ATLS, being favored by the presence of cation vacancies in the apatite. Transport properties of the systems were studied by impedance spectroscopy and oxygen isotope exchange technique. The latter indirectly shows that not only channel/interstitial oxygen atoms can be involved in the oxide-ion migration but also those of tetrahedrons.     

Zur Bestimmung der gebundenen Salzs?ure im Magensaft

Ohne Zusammenfassung     

Performance of slotted pores in particle manufacture using rotating membrane emulsification

This paper addresses the use of different slotted pores in rotating membrane emulsification technology.Pores of square and rectangular shapes were studied to understand the effect of aspect ratio (1-3.5) and their orientation on oil droplet formation.Increasing the membrane rotation speed decreased the droplet size,and the oil droplets produced were more uniform using slotted pores as compared to circular geometry.At a given rotation speed,the droplet size was mainly determined by the pore size and the fluid velocity of oil through the pore (pore fluid velocity).The ratio of droplet diameter to the equivalent diameter of the slotted pore increased with the pore fluid velocity.At a given pore fluid velocity and rotation speed,pore orientation significantly influences the droplet formation rate: horizontally disposed pores (with their longer side perpendicular to the membrane axis) generate droplets at double the rate of vertically disposed pores.This work indicates practical benefits in the use of slotted membranes over conventional methods.     

Investigation of the mobility of paraffin molecules in channel urea clathrates by nuclear magnetic resonance relaxation spectroscopy

The temperature dependence of the proton spin-lattice relaxation time (T ₁) is investigated for channel urea clathrates with paraffin molecules. The results obtained are interpreted within the reorientational model of paraffin molecules and their fragments in clathrate channels. The specific features of the dynamics of normal paraffins in urea clathrates are associated with incommensurate regions in the structure of these compounds.     

Reactions of Podophyllotoxin with DDQ

Introduction 2, 3-Dichloro-5, 6-dicyanobenzoquinone (DDQ) can react with lignans of the mono- arylidene-butyrolactone1, aryltetralin2, dibenzylbutane3 and aryltetralin-butyrolactone4,5 series. We have studied the reactions of this reagent with podophyllotoxin 1, which is a well-known natural product on account of its long history of use in folk medicine and the biological activity of its many derivatives6. In particular, derivatives of 4-demethyl epipodophyllotoxin are used in cancer chemo…