Comparative in vitro and in vivo taste assessment of liquid praziquantel formulations

The taste of pharmaceuticals strongly affects the compliance of patients. This study investigated the applicability of the electronic tongue and rodent brief-access taste aversion (BATA) model for the bitter compound praziquantel (PZQ) and taste masked liquid formulations for PZQ. In a comparative study maltodextrin (MD) Kleptose® linecaps 17 was selected as an alternative taste masking agent to two cyclodextrins; hydroxypropyl-beta-cyclodextrin (HP-β-CD) and sulfobutyl ether-beta-cyclodextrin (SBE-β-CD). A phase solubility study showed the highest affinity and solubilization capabilities for SBE-β-CD over HP-β-CD and MD, suggesting the highest taste masking ability for SBE-β-CD. No reliable results were achieved for PZQ with the Insent electronic tongue. Thus this system was not used for further evaluation of solutions with MD and CDs to confirm the results of the solubility study. In contrast the BATA model demonstrated conclusive responses for the aversiveness of PZQ. The concentration of PZQ inhibiting 50% of water lick numbers (called IC50 value) was 0.06mg/ml. In contrast to the phase solubility study, the MD enabled an equal taste masking effect in vivo in comparison to both CDs. Moreover HP-β-CD showed superior taste masking capabilities for PZQ compared to SBE-β-CD as the SBE-β-CD itself was less acceptable for the rodents than HP-β-CD. In conclusion, the BATA model was identified as a more efficient taste assessment tool for the pure PZQ and liquid formulations in contrast to the electronic tongue and the phase solubility study

First principles investigation of exchange interactions in quasi-one-dimensional antiferromagnet CaV2O4

The effect of orbital degrees of freedom on the exchange interactions in the spin-1 quasi-one-dimensional antiferromagnet CaV2O4 is systematically studied. For this purpose a realistic low-energy model with the parameters derived from the first-principles calculations is constructed. The exchange interactions are calculated using both the theory of infinitesimal spin rotations near the mean-field ground state and the superexchange model, which provide a consistent description. The obtained behaviour of exchange interactions substantially differs from the previously proposed phenomenological picture based on the magnetic measurements and structural considerations, namely: (i) Despite quasi-one-dimensional character of the crystal structure, consisting of the zigzag chains of edge-sharing VO6 octahedra, the electronic structure is essentially three-dimensional, that leads to finite interactions between the chains; (ii) The exchange interactions along the legs of the chains appear to dominate; and (iii) There is a substantial difference of exchange interactions in two crystallographically inequivalent chains. The combination of these three factors successfully reproduces the behaviour of experimental magnetic susceptibility.Comment: 15 pages, 6 figures, supplementary materia

Mechanokatalytische Prozesse in der Kugelmühle

Im Rahmen dieser Arbeit wurden Prozesse für kontinuierliche heterogen katalysierte Gasphasen-Reaktionen unter den Bedingungen der mechanochemischen Aktivierung eines festen Katalysators in der Kugelmühle entwickelt. Es wurden die CO-Oxidation und die Propenoxidation an verschiedenen Metalloxid-Katalysatoren und geträgerten Goldkatalysatoren untersucht. Es konnte gezeigt werden, dass das Vermahlen des Katalysators während der Reaktion zu einer erhöhten Aktivität führt. Vergleichsversuche in einem Festbettreaktor über vorvermahlenen Katalysatoren zeigen eine Aktivitätssteigerung um mehrere Größenordnungen, wenn die Reaktion unter mechanokatalytischen Bedingungen durchgeführt wurde. Wir vermuten, dass der schlagartige Rückgang der Aktivität nach Anhalten der Mühle sowohl durch ein Fehlen direkter, Reaktivität-auslösender Aufpralle als auch das Verschwinden kurzlebiger Defekte hervorgerufen wird

Oscillatory combustion of propene during in situ mechanical activation of solid catalysts

Mechanochemical activation of solids can lead to a strong increase in their activity as catalysts in heterogeneously catalyzed reactions. In the following, we report on the effects of solid catalyst activation during ball milling that lead to oscillatory behavior in CO and CO2 formation during propene oxidation. The oscillations arise under in situ ball milling conditions over chromium(III) oxide (Cr2O3) and cerium(IV) oxide (CeO2), respectively. The experiments were conducted under continuous gas flow at ambient pressure and temperature, using both a modified steel and a tungsten carbide milling vessel. Abrasion of particles from the steel milling vessel could be eliminated as the sole cause for the oscillations through substitution by a tungsten carbide milling vessel. The intensity and frequency of oscillations are shown to be dependent on the propene-to-oxygen ratio, the milling frequency, milling ball size and metal oxide used. Overall, Cr2O3 shows higher activity for oscillatory propene combustion under in situ mechanical activation than CeO2

Data for a pre-performance test of self-developed electronic tongue sensors

This article presents data, which can be applied for a pre-performance test of self-developed electronic tongue sensors. Contained data is related to the research article “Impact of Sodium Lauryl Sulfate in oral liquids on E-Tongue Measurements” (http://dx.doi.org/10.1016/j.ijpharm.2016.10.045; (L.I. Immohr, R. Turner, M. Pein-Hackelbusch, 2016) [1]). Sensor responses were obtained from 10 subsequent measurements and four different concentrations of quinine hydrochloride by electronic tongue (TS-5000Z, Insent Inc., Atsugi-Shi, Japan) measurements. Based on the data for the pre-performance testing, which were calculated based on the fluctuation range of the sensor responses around the median, stability criteria and required preconditions cycles were defined

An Orders-of-Magnitude Increase in the Rate of the Solid-Catalyzed CO Oxidation by In Situ Ball Milling

Shaken, not stirred: CO oxidation was carried out continuously in a shaker ball mill. During milling, the reaction rate increases dramatically, but drops rapidly to zero when the mill is stopped. Compared to a conventional experiment in a plug‐flow reactor, the rate of a ball‐mill reaction catalyzed by Cr2O3 is three orders of magnitude higher at room temperature and one order of magnitude higher at 100°C