Development of organosilicone–polyurethanes as stone preservation and consolidation materials

Two organosilicone-modified polyurethanes are investigated as potential materials for the conservation and consolidation of natural stones. The materials are low molecular weight oligomers at the application stage and react with the humidity of the air to give polymers, forming continuous microlayers. The two differ in the length of the organosilicone chain, resulting in pronounced differences in their physical state: one forms a brittle glassy material (T_g ≈ 70°C). and the other, a soft rubbery material (T_g ≈ −100°C). The rate of the polymerization of the prepolymers was investigated at different conditions, showing a strong dependence on the presence of a catalyst and air humidity. Both these favorable conditions exist probably in the natural stone pores, enhancing the formation of the protective hydrophobic internal microlayer. © 1996 John Wiley & Sons, Inc.     

Diazoverbindungen. 72. (Diazoalkyl)phosphane – Synthese durch elektrophile Diazoalkansubstitution und oxidative Additionsreaktionen am Phosphor

Diazo Compounds. 72. Diazoalkylphosphanes – Synthesis by Electrophilic Diazoalkane Substitution and Oxidative Addition Reactions at Phosphorus Electrophilic diazoalkane substitution of the diazomethyl compounds 1a,b with the chloro phosphanes 2a-o in the presence of lithium diethylamide yields the diazoalkyl phosphanes 3a-z . Oxidative addition of oxygen, sulfur and selenium at phosphorus leads into the series of oxo, thioxo and selenoxo phosphanes having diazoalkyl substituents ( 4a-d, 5a-m and 7a-d ). The silyl group of 5n,o is cleaved by chromatography on aluminium oxide to yield the (diazomethyl)phosphane sulfides 6a,b .     

Impact of neurite alignment on organelle motion

Intracellular transport is pivotal for cell growth and survival. Malfunctions in this process have been associated with devastating neurodegenerative diseases, highlighting the need for a deeper understanding of the mechanisms involved. Here, we use an experimental methodology that leads neurites of differentiated PC12 cells into either one of two configurations: a one-dimensional configuration, where the neurites align along lines, or a two-dimensional configuration, where the neurites adopt a random orientation and shape on a flat substrate. We subsequently monitored the motion of functional organelles, the lysosomes, inside the neurites. Implementing a time-resolved analysis of the mean-squared displacement, we quantitatively characterized distinct motion modes of the lysosomes. Our results indicate that neurite alignment gives rise to faster diffusive and super-diffusive lysosomal motion than the situation in which the neurites are randomly oriented. After inducing lysosome swelling through an osmotic challenge by sucrose, we confirmed the predicted slowdown in diffusive mobility. Surprisingly, we found that the swelling-induced mobility change affected each of the (sub-/super-)diffusive motion modes differently and depended on the alignment configuration of the neurites. Our findings imply that intracellular transport is significantly and robustly dependent on cell morphology, which might in part be controlled by the extracellular matrix.     

Donorsubstituierte 2,4-Diazacyclopentadienone und indigoide 1,3,5,7-Tetraazafulvalene

Donor Substituted 2,4-Diazacyclopentadienones and Indigoid 1,3,5,7-Tetraazafulvalenes Hydrolysis of tris(diethylamino)imidazolylium chloride gives rise to 2,5-bis-diethyl-amino-4H-imidazolin-4-one; thiolysis leads, depending on conditions, to 2,5-bis-diethylamino-4H-imidazolin-4-thione or potassium 2,6-bis-diethylamino-1,3,5,7-tetraazafulvalene-4,8-dithiolate. The latter can be protonated to form green 2,6-bis(dimethylamino)-3,4,7,8-tetrahydro-1,3,5,7-tetraaza-fulvalen-4,8-dithione, a new indigoid compound, and alkylated to give blue 2,6-bis-diethylamino-4,8-bis-alkylthio-1,3,5,7-tetraazafulvalenes. Treatment of 2,5-bis-diethylamino-4H-imidazolin-4-thione with copper furnishes 2,6,4,8-tetrakis-diethylamino-1,3,5,7-tetraazafulvalene. – Oxidation of 2,6-bis-dimethylamino-3,4,7,8-tetrahydro-1,3,5,7-tetraazafulvalen-4,8-dithione gives rise to (2,2′-bis-diethylamino-4,4′-bi(4H-imidazol)-5,5′-dithione, corresponding to dehydroindigo, and reduction leads to a colorless compound, corresponding to leucoindigo.     

Effect of Ions and Sequence Variants on the Antagonist Binding Properties of the Histamine H1 Receptor

The histamine H₁ receptor (H₁R) is a G protein-coupled receptor (GPCR) and represents a main target in the treatment of allergic reactions as well as inflammatory reactions and depressions. Although the overall effect of antagonists on H₁ function has been extensively investigated, rather little is known about the potential modulatory effect of ions or sequence variants on antagonist binding. We investigated the dynamics of a phosphate ion present in the crystal structure and of a sodium ion, for which we determined the position in the allosteric pocket by metadynamics simulations. Both types of ions exhibit significant dynamics within their binding site; however, some key contacts remain stable over the simulation time, which might be exploited to develop more potent drugs targeting these sites. The dynamics of the ions is almost unaffected by the presence or absence of doxepin, as also reflected in their small effect (less than 1 kcal·mol⁻¹) on doxepin binding affinity. We also examined the effect of four H₁R sequence variants observed in the human population on doxepin binding. These variants cause a reduction in doxepin affinity of up to 2.5 kcal·mol⁻¹, indicating that personalized medical treatments that take into account individual mutation patterns could increase precision in the dosage of GPCR-targeting drugs.     

Flavine und Zimtsäurederivat im Zusammenhang mit der lichtinduzierten Blattöffnung bei Albizia julibrissin

Flavins and Chinamoyl Derivatives in Relation to the Light-induced Leaf Opening in Albizia julibrissin In search of blue-light photoreceptors for light-induced leaf opening we isolated from the aqueous extract of Albizia julibrissin Durazz. two flavins by adsorption on XAD-4 and separation with HPLC. One sample was identified as riboflavin 1a. In the hydrolysate of the second flavin fraction we found another dimethylisoalloxazine with a C₅-side chain. Furthermore we isolated the cinnamoyl derivatives 3-O-(4-hydroxy-trans-cinnamoyl) quinic acid 2 and 3-O-(3,4-dihydroxy-trans-cinnamoyl)-4-O-malonyl-quinic acid 3 which formed charge transfer complexes with the flavins in the XAD-fraction. As a model complex we examined the absorption behaviour of the complex between riboflavin and chlorogenic acid. Using the association constant, we calculated the absorption spectrum and could show that a complex between a flavin and a phenolic compound is a possible blue-light photoreceptor for the light-induced leaf opening in Albizia julibrissin.     

Determination of Glyphosate and Its Metabolite AMPA (Aminomethylphosphonic Acid) in Cereals After Derivatization by Isotope Dilution and UPLC-MS/MS”

A straightforward analytical method has been developed for the determination of glyphosate and aminomethylphosphonic acid (AMPA), its major metabolite in cereals. This method entails a rapid extraction and derivatization with 9-fluorenylmethyl chloroformate followed by separation with a conventional reversed-phase rapid chromatography used in daily routine analysis and detection by electrospray ionization tandem mass spectrometry. To overcome matrix effects and compensate for any analyte losses during sample treatment, an isotopic dilution approach was used. Since 2010, the monitoring of cereals for the widely used herbicide glyphosate is obligatory to all European Union (EU)-member states, laid down in Commission Regulation (EC) No. 1213/2008. Hence, there is definitively a need for a reliable and easy-to-handle analytical method for monitoring of this compound. The proposed method can be run without having to make time-consuming changes on the equipment used for daily routine analysis. The analytical performance of the method was evaluated according to SANCO/10684/2009 criteria and demonstrated that this method is rugged and cost-effective, therefore suitable for monitoring purposes as well as legislative enforcements within the EU. The apparent recoveries of both analytes were between 97% and 113% with relative standard deviations less than 20%. The limits of quantification of glyphosate and AMPA were 0.02 mg/kg in cereal matrices. Finally, the accuracy of the method was assessed by analyzing a proficiency test material which was available from a previous round (EUPT-C4).     

Cloning of the bile salt hydrolase (bsh) gene from Enterococcus faecium FAIR-E 345 and chromosomal location of bsh genes in food enterococci

Enterococcus faecium strain FAIR-E 345 isolated from food was shown to possess bile salt hydrolase (Bsh) activity in a plate screening assay and by high-performance liquid chromatography analysis. The bsh gene was cloned and sequenced. DNA sequence analysis revealed that it encoded a protein of 324 amino acids, with pI 4.877. A bsh gene probe was prepared from the cloned bsh gene and was used for probing plasmid and total genomic DNA of Bsh-positive enterococci isolated from food to determine the genomic location of their bsh genes. This probe was able to detect the bsh gene among total genomic DNA preparations but not from plasmid preparations of 10 plasmid-bearing Enterococcus strains. However, the probe could detect the bsh gene from total genomic DNA preparations of 12 Enterococcus strains that did not contain detectable plasmid DNA. In no cases did the probe hybridize with plasmid DNA preparations, suggesting that the bsh gene among enterococci is probably generally chromosomally encoded. This presumptive chromosomal location of bsh genes among food enterococci suggests that transfer of this trait by conjugative plasmids is unlikely.     

Determination of phenols in coffee

The structure and quantity of phenols, occurring in two different roasted Robusta coffees and in four samples of roast coffee, were investigated. Identification and quantification were carried out after special extraction procedures and clean-up methods by gas chromatography/mass spectrometry. The quantities of 35 phenols investigated ranged from below 0.1 mg/kg to more than 1000 mg/kg. Sixteen phenols were identified in coffee for the first time.