Modelling the Effect of Process Parameters on the Wet Extrusion and Spheronisation of High-Loaded Nicotinamide Pellets Using a Quality by Design Approach

Open access articleThe aim of the present study was to develop an alternative process to spray granulation in order to prepare high loaded spherical nicotinamide (NAM) pellets by wet extrusion and spheronisation. Therefore, a quality by design approach was implemented to model the effect of the process parameters of the extrusion-spheronisation process on the roundness, roughness and useable yield of the obtained pellets. The obtained results were compared to spray granulated NAM particles regarding their characteristics and their release profile in vitro after the application of an ileocolon targeted shellac coating. The wet extrusion-spheronisation process was able to form highly loaded NAM pellets (80%) with a spherical shape and a high useable yield of about 90%. However, the water content range was rather narrow between 24.7% and 21.3%. The design of experiments (DoE), showed that the spheronisation conditions speed, time and load had a greater impact on the quality attributes of the pellets than the extrusion conditions screw design, screw speed and solid feed rate (hopper speed). The best results were obtained using a low load (15 g) combined with a high rotation speed (900 m/min) and a low time (3–3.5 min). In comparison to spray granulated NAM pellets, the extruded NAM pellets resulted in a higher roughness and a higher useable yield (63% vs. 92%). Finally, the coating and dissolution test showed that the extruded and spheronised pellets are also suitable for a protective coating with an ileocolonic release profile. Due to its lower specific surface area, the required shellac concentration could be reduced while maintaining the release profil

Fluorine in silicate glasses: A multinuclear nuclear magnetic resonance study

Anhydrous nepheline, jadeite, and albite glasses doped with F as well as hydrous F-containing haplogranitic glasses were investigated using 19F combined rotation and multiple-pulse spectroscopy; 19F → 29Si cross-polarization/magic angle spinning (MAS); and high-power 19F decoupled 29Si, 23Na, and 27Al MAS nuclear magnetic resonance methods. Fluorine preferentially coordinates with Al to form octahedral AlF63− complexes in all glasses studied. In addition, F anions bridging two Al cations, units containing octahedral Al coordinated by both O and F, or tetrahedral Al-F complexes might be present. The presence of Si-F bonds cannot be entirely ruled out but appears unlikely on the basis of the 19F → 29Si CP/MAS spectra. There is no evidence for any significant coordination of F with alkalis in the glasses studied. 23Na spectra are identical for the samples and their F-free equivalents and the spectra do not change upon decoupling of 19F. The speciation of F in the hydrous and anhydrous glasses appears to be very similar. Over the range of F contents studied ( up to 5 wt.% ), there seems to be hardly any dependence of F speciation on the concentration of F in the samples. The spectroscopic results explain the decrease of the viscosity of silicate melts with increasing F content by removal of Al from bridging AlO4-units due to complexing with F, which causes depolymerization of the melt. The same mechanism can account for the shift of the eutectic point in the haplogranite system to more feldspar-rich compositions with increasing F content, and for the peraluminous composition of most F-rich granites. Liquid immiscibility in F-rich granitic melts might be caused by formation of (Na,K)3AlF6 units in the melt with little or no interaction with the silicate component. The presence of F in granitic melts might increase the solubility of high field strength cations by making nonbridging O atoms available which form complexes with these cations

Wie viel Arbeit macht die Aufzucht von Ökologischen Junghennen? Arbeitwirtschaftlicher Vergleich der konventionellen und ökologischen Aufzucht von Legehennen

Organic pullets are reared with daylight and are not beak-trimmed. Therefore, certain provisions are needed in order to prevent feather-pecking and cannibalism. Respec-tive guidelines are set by the German Organic Associations. It was the goal of this study to investigate whether the higher rearing standards are associated with an increased labour demand compared to conventional rearing systems. Using a ques-tionnaire, data from 32 hen-houses (10 conventional and 6 organic barn systems, 10 conventional and 6 organic aviary systems) about duration and number of working procedures were collected and exemplary models calculated. Total labour demand was between 2.36 and 7.37 worker`s hours/100 pullets. It did not differ between or-ganic and conventional rearing when comparing similar flock sizes, but were partly differently allocated to the different working procedures. On average, organic farms had smaller flocks, and there was a large influence of flock size on labour demand with small houses requiring most labour per hen. Also aviaries were more labour demanding than barn systems, but were usually associated with higher flock sizes. Our results indicate that improved pullet rearing that allows the birds to perform their natural behaviour more completely, does not necessarily cause higher labour re-quirements

Studying The Collector Performance Of Updraft Solar Chimney Power Plant

In the shadow of increasing energy consumption, renewable energy is the best choicefor a sustainable environment. The solar chimney power plant (SCPP) is a new technology, many researchers are paying their attention to improve its performance. In this study, experimental and numerical studies were used to understand the effect of the collector geometry on the SCPP performance. The SCPP prototype under our investigation is installed in Aswan city, its chimney height is 20m, its diameter is 1 m and the collector is a square which has a side length of 28.5m. Three dimensional CFD simulations were made to calculate the temperature and velocity distribution inside two different shapes of SCPP collector. The conclusion is that the square shaped collector achieved higher output power than the circular collector by 7.6 % at the same surface area exposed to solar radiation

Fluorine in silicate glasses: A multinuclear nuclear magnetic resonance study

Anhydrous nepheline, jadeite, and albite glasses doped with F as well as hydrous F-containing haplogranitic glasses were investigated using 19F combined rotation and multiple-pulse spectroscopy; 19F → 29Si cross-polarization/magic angle spinning (MAS); and high-power 19F decoupled 29Si, 23Na, and 27Al MAS nuclear magnetic resonance methods. Fluorine preferentially coordinates with Al to form octahedral AlF63− complexes in all glasses studied. In addition, F anions bridging two Al cations, units containing octahedral Al coordinated by both O and F, or tetrahedral Al-F complexes might be present. The presence of Si-F bonds cannot be entirely ruled out but appears unlikely on the basis of the 19F → 29Si CP/MAS spectra. There is no evidence for any significant coordination of F with alkalis in the glasses studied. 23Na spectra are identical for the samples and their F-free equivalents and the spectra do not change upon decoupling of 19F. The speciation of F in the hydrous and anhydrous glasses appears to be very similar. Over the range of F contents studied ( up to 5 wt.% ), there seems to be hardly any dependence of F speciation on the concentration of F in the samples. The spectroscopic results explain the decrease of the viscosity of silicate melts with increasing F content by removal of Al from bridging AlO4-units due to complexing with F, which causes depolymerization of the melt. The same mechanism can account for the shift of the eutectic point in the haplogranite system to more feldspar-rich compositions with increasing F content, and for the peraluminous composition of most F-rich granites. Liquid immiscibility in F-rich granitic melts might be caused by formation of (Na,K)3AlF6 units in the melt with little or no interaction with the silicate component. The presence of F in granitic melts might increase the solubility of high field strength cations by making nonbridging O atoms available which form complexes with these cations

Another step toward DNA selective targeting: NiII and CuII complexes of a Schiff base ligand able to bind gene promoter G-quadruplexes

DNA G-rich sequences are able to form four-stranded structures organized in stacked guanine tetrads. These structures, called G-quadruplexes, were found to have an important role in the regulation of oncogenes expression and became, for such a reason, appealing targets for anticancer drugs. Aiming at finding selective G-quadruplex binders, we have designed, synthesized and characterized a new water soluble Salen-like Schiff base ligand and its NiII and CuII metal complexes. UV-Vis, circular dichroism and FRET measurements indicated that the nickel complex can stabilize oncogene promoter G-quadruplexes with high selectivity, presenting no interactions with duplex DNA at all. The same compound exhibited dose-dependent cytotoxic activity in MCF-7 breast cancer cells when combined with lipofectamine as lipophilic carrier

Controlled assembly of SNAP-PNA-fluorophore systems on DNA templates to produce fluorescence resonance energy transfer

The SNAP protein is a widely used self-labeling tag that can be used for tracking protein localization and trafficking in living systems. A model system providing controlled alignment of SNAP-tag units can provide a new way to study clustering of fusion proteins. In this work, fluorescent SNAP-PNA conjugates were controllably assembled on DNA frameworks forming dimers, trimers, and tetramers. Modification of peptide nucleic acid (PNA) with the O6-benzyl guanine (BG) group allowed the generation of site-selective covalent links between PNA and the SNAP protein. The modified BG-PNAs were labeled with fluorescent Atto dyes and subsequently chemo-selectively conjugated to SNAP protein. Efficient assembly into dimer and oligomer forms was verified via size exclusion chromatography (SEC), electrophoresis (SDS-PAGE), and fluorescence spectroscopy. DNA directed assembly of homo- and hetero-dimers of SNAP-PNA constructs induced homo- and hetero-FRET, respectively. Longer DNA scaffolds controllably aligned similar fluorescent SNAP-PNA constructs into higher oligomers exhibiting homo-FRET. The combined SEC and homo-FRET studies indicated the 1:1 and saturated assemblies of SNAP-PNA-fluorophore:DNA formed preferentially in this system. This suggested a kinetic/stoichiometric model of assembly rather than binomially distributed products. These BG-PNA-fluorophore building blocks allow facile introduction of fluorophores and/or assembly directing moieties onto any protein containing SNAP. Template directed assembly of PNA modified SNAP proteins may be used to investigate clustering behavior both with and without fluorescent labels which may find use in the study of assembly processes in cells