Solution growth of spherulitic rod and platelet calcium phosphate assemblies through polymer-assisted mesoscopic transformations

Solution growth of apatite its precursors in the presence of urea commercial gelatin is found to lead, under appropriate conditions, to a rich spectrum of morphologies, among them high aspect ratio needles in uniform sturdy spherulitic assemblies resulting from a herein documented morphological ‘Chrysalis Transformation’; the latter transformation involves the growth of parallel arrays of high aspect ratio needles within micron-scale tablets the formation of a radial needle arrangement upon disruption of tablet wrapping. A different level of gelatin leads to the formation of sturdy platelet-based spherulites through another morphological transformation. We also probe the role of four simple synthetic water-soluble polymers; we find that three of them (poly(vinyl alcohol), polyvinylpyrrolidone and polyacrylamide)) also affect substantially the assembly habits of apatite; the effect is similar to that of gelatin but the attained control is less perfect/complete. The case of poly(vinyl alcohol) provides, through variation of the degree of hydrolysis, insights as regards the chain architecture features that might favor morphological transformations. Morphological transformations of particle assemblies documented herein constitute novel ways of generating dense quasi-isotropic reinforcements with high aspect ratio ceramic particles; it becomes possible to tailor calcium phosphate phases at the structural level of crystal assembly.     

Indolylfuran,a potent aryl hydrocarbon receptor agonist from sauerkraut,interacts with the oestrogen pathway

Numerous ligands of the aryl hydrocarbon receptor (AhR) have been found in plants, especially edible plants, such as cruciferous vegetables, which exert beneficent health effects. A potent activator of the AhR was found in sauerkraut juice. The isolated active ingredient was identified as the novel AhR ligand, (1-(2-furanyl)2-(3-indolyl)ethanone, common name indolylfuran. The isolated and the synthesised compound exerted similar potencies; their EC₅₀-values in an AhR transactivation assay were 160 and 123 nM, respectively. Our in vivo studies confirm and enlighten basic interactions between the AhR and oestrogen receptors (ERs). Further anti-oestrogenic effects of sauerkraut extract were shown. Indolylfuran regulates ER α and β expression, most likely via the AhR pathway, since indolylfuran had no effect on uterus weight and did not agonise ERα. Sauerkraut and indolylfuran may have potential for the prevention or treatment of diseases through modulation of AhR regulation and, indirectly, the ER pathway.     

Characterization and Classification of Extra Virgin Olive Oil from Five Less Well-Known Greek Olive Cultivars

The present study comprises the second part of an ongoing study focusing on olive oil from five less well‐known Greek cultivars for three of which there are no data available in the literature regarding their chemical composition. A total of 74 olive oil samples were collected during the harvesting periods 2012–2013 and 2013–2014. Headspace‐solid phase microextraction was applied to determine the olive oil volatile profile. Fifty‐six compounds were identified and semi‐quantified by CG–MS. Furthermore, fatty acid composition, conventional quality parameters and color parameters were determined in an effort to characterize and differentiate olive oils according to cultivar. All samples were characterized as extra virgin olive oils. Data obtained showed significant differences between the cultivars. Multi‐element analysis in combination with chemometrics resulted in a high classification rate of 86.5 % for the combination of volatiles plus color, 89.2 % for the combination of VC plus FA, and 91.9 % for the combination of FA composition plus color plus CQP.     

Ageing of dental zirconia ceramics

An in vitro study was designed to monitor the t–m transformation of biomedical grade 3Y-TZP ceramics produced from two ready-to-press granulated powders of the same nominal chemical composition, but differing in their specific surface area. Disc-shaped specimens were formed by uni-axial dry-pressing and sintering in air for 2 h in the temperature range 1400–1550 °C, resulting in a mean grain size of 0.26–0.57 μm. The sintered specimens were subjected to accelerated ageing in deionized water at 134 °C for up to 48 h and verified in terms of the amount of the transformed monoclinic fraction, the thickness of the transformed layer, and the bi-axial flexural strength. The sintering-temperature-dependent transformability during ageing was confirmed, whereby the role of the starting-powder characteristics was more pronounced at lower sintering temperatures and was almost negligible at higher sintering temperatures.     

Suppressed Reactivity of AlN Powder in Water at 5°C

The hydrolysis behavior of AlN powder suspensions (5–25 wt%) at 5°C has been investigated to explore the impact of low temperatures on the hydrolysis behavior. Throughout the 312‐h long experiment, the pH value of the suspensions was below 9, where the hydrolysis remained in the induction period and was eventually suppressed due to the formation of a few‐nanometers‐thick film of amorphous aluminum hydroxide gel around the AlN particles, acting as a passivation layer. Moreover, the aqueous part of the suspension possessed a remarkably high value of dissolved [Al(III)]_aq, being an order of magnitude higher at a given pH value than the aqueous AlCl₃ solution.     

Rheological properties of re-melted paraffin-wax suspensions used for LPIM

The influence of re-melting of suspensions of ceramic powder and paraffin-wax used for LPIM on the yield stress and the flow behaviour was investigated. As a model system we used alumina powder and paraffin-wax, which has a liquid/solid phase transition at around 58 °C. The only parameter that was changed during this study was the number of particles per unit volume and, consequently, the number of attractive, interparticle interactions in the suspensions per unit volume.During cooling the particles took up closer interparticle distances than in the prepared suspension due to the huge shrinkage associated with paraffin-wax, which occurs below the liquid–solid phase transition. This resulted in an increased, attractive interparticle interaction (and so an increased yield stress) and an increase in the strength of attractive particle network formed after re-melting, which can be destroyed by homogenization, as was shown during the flow-curve measurements, and the initial flow properties of the paraffin-wax suspensions can be regained.     

Weakly Flocculated Aqueous Alumina Suspensions Prepared by the Addition of Mg(II) Ions

Well-dispersed aqueous alumina suspensions were prepared at an inherent pH via the addition of an anionic dispersant. With the addition of an appropriate amount of magnesium acetate to such a suspension, the surface charge of the particles was neutralized, which was reflected in the destabilization of the slurry. Because of the formation of coordinative bonds between the Mg ion and the two dissociated carboxylic groups of the dispersant, a thin neutral layer was formed on the surface of the particles, which established a nontouching particle network and resulted in a weakly flocculated suspension.     

Structural requirements of synthetic oligosaccharides to bind monoclonal antibodies against Chlamydia lipopolysaccharide

Monoclonal antibodies were generated against a synthetic glycoconjugate containing the trisaccharide alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo (Kdo, 3-deoxy-D-manno-2-octulopyranosonic acid) which represents the genus-specific epitope of the lipopolysaccharide from the obligatory intracellular human pathogen Chlamydia. Antibodies of all immunoglobulin G isotypes were obtained and characterized by enzyme immunobinding and inhibition assays using the immunizing antigen as well as chemically synthesized derivatives of the Kdo trisaccharide. The latter contained (1) one of the three residues in beta- instead of alpha-linkage, (2) a Kdo residue the carboxyl group of which had been reduced to a CH2OH group (Kdo(C1-red)), or (3) changing the linkage of the terminal Kdo from 2-->8 to 2-->4. Only one compound, namely, alpha-Kdo-(2-->8)-alpha-Kdo(C1-red)-(2-->4)-alpha-Kdo exhibited binding to and inhibition of Kdo trisaccharide-specific antibodies, whereas all other compounds were not active. Structural and conformational investigations using NMR spectroscopy at high field on the allyl glycosides of the oligosaccharides 6-12 confirmed the conformational similarities between those structures 4, 5, and 10 which were able to bind to the antibodies investigated.