Improved spectrophotometric vitellogenin determination via alkali-labile phosphate in fish plasma–a cost effective approach for assessment of endocrine disruption

Vitellogenin (VTG) is a well known protein biomarker for exposure to environmental estrogens and possible endocrine disruption in fish. VTG is very dominant in plasma after the onset of vitellogenesis and the protein is heavily phosphorylated. This enables indirect quantification through measurement of alkali-labile protein bound phosphate (ALP) as an alternative to the more expensive enzyme linked immunosorbent assay. Good correlation has previously been shown between ALP and actual VTG levels but little effort has been made to investigate the method in an analytical way e.g., to assure the origin of the measured phosphate. During this method development care has been taken to rule out non-VTG sources of phosphate such as phospholipids and free phosphate in the blood plasma. Sample preparation has been simplified and unnecessary steps have been omitted. The common spectrophotometric measurement for ALP involves measurement at two wavelengths and calculation of corrected absorbance values. With a quick phase separation step the spectrophotometric phosphate determination using molybdic acid and ascorbic acid has been improved and all matrix interference has been eliminated. The final ALP method presented here has a detection limit of 3.2 µg PO₄ ^3?/ml plasma which is six times lower than similar methods and it also has less variability. A high sample throughput in comparison to previous ALP methods is possible after scaling down sample and reagent volumes to fit in a 96 well microtiter plate. The cost for buying all chemicals and plastic consumer goods for setting up the indirect protocol for the analysis of 1000 samples is only circa 350 euro. This is only 1% of the material cost for buying commercially available test kit for direct quantification of VTG in the same number of samples. The ALP method should thus be of interest also for applied scientists outside advanced research laboratories.     

Dielectric properties of lignin and glucomannan as determined by spectroscopic ellipsometry and Lifshitz estimates of non-retarded Hamaker constants

We present in this study a quantitative estimate of the dispersive interactions between lignin, hemicellulose and cellulose, which are the dominating components in wood and also extensively used to produce paper and packaging materials. The dielectric properties in the UV-visible region of spin-coated films of pure lignin and glucomannan were determined by spectroscopic ellipsometry. The non-retarded Hamaker constants were estimated from the determined spectral parameters using Lifshitz theory for lignin and glucomannan interacting with cellulose, titania and calcium carbonate in vacuum, water and hexane. The Hamaker constants for the different combinations of cellulose, lignin and glucomannan fall within a relatively narrow range of 35–58 and 8–17 zJ, for the values in vacuum (air) and water, respectively. The estimated Hamaker constants for the interactions of the wood components with TiO₂ and CaCO₃, common additives in paper, in water range from 3 to 19 zJ, thus being similar in magnitude as the interactions between the wood components themselves. In contrast, the Hamaker constant is essentially zero for glucomannan interacting with calcium carbonate in hexane. The Hamaker constants for lignin, hemicellulose and cellulose determined in this study can provide information regarding the surface interactions important for e.g. adhesion, friction, swelling and wetting in paper processing as well as for the resulting behavior of paper products.     

Organocatalytic strategies for the construction of optically active imidazoles, oxazoles, and thiazoles

This study demonstrates the first enantioselective synthesis of hydroxyalkyl- and aminoalkyl-substituted imidazoles, oxazoles, and thiazoles. The approach developed utilizes a highly effective one-pot reaction cascade that consists of either an organocatalytic epoxidation or aziridination of α,β-unsaturated aldehydes coupled with a [3+2]-annulation, in which amidines, ureas, or thioureas act as effective 1,3-dinucleophilic species. The methodology described benefits from low catalyst loadings, commercially and readily available starting materials, and mild reaction conditions.     

Anisotropy of cell wall polymers in branches of hardwood and softwood: a polarized FTIR study

The mechanical and physical properties of wood fibres are dependent on the organisation of their constituent polymers (cellulose, hemicellulose and lignin). Fourier Transform Infrared (FTIR) microscopy was used to examine the anisotropy of the main wood polymers in isolated cell wall fragments from branches of maple and Serbian spruce. Polarised FTIR measurements indicated an anisotropy, i.e. orientation of the cellulose microfibrils that was more or less parallel to the longitudinal axis of the cell wall. The hemicelluloses, glucomannan and xylan appeared to have a close link to the orientation of the cellulose and, thus, an orientation more parallel to the axis of the cell wall. An important result is that, in both maple and spruce samples, lignin was found to be organised in a parallel way in relation to the longitudinal cell wall axis, as well as to the cellulose. The results show that, despite the different lignin precursors and the different types of hemicelluloses in these two kinds of wood, lignin has a similar orientation, when it comes to the longitudinal axis of the cell wall.     

Unusual Light Spectroscopic Properties of a 2-Pyridone-Based Multi-Ring-Fused Fluorescent Scaffold

UV-VIS absorption and fluorescence spectroscopic properties of six related polyaromatic 2-pyridones have been studied. Excitation of the lowest and rather weak and structure-less transition [ε _max (430 nm)?≈?3,000 mol^?1dm³cm^?1] gives rise to a broad fluorescence band in the visible region, for these compounds. These S ₀ ? S ₁ transitions are compatible with symmetrically forbidden transitions, promoted by intensity borrowing, as is revealed by fluorescence depolarisation data. With one exception, all compounds exhibit strong fluorescence, with quantum yields in glycerol varying between 40% and 70%. The corresponding fluorescence lifetimes range from 11 ns to 17 ns, while the radiative lifetimes are very similar (≈26 ns), for all compounds. Interestingly and rarely observed, the calculated radiative lifetimes for the weak absorption band are significantly longer, i.e. between 37 and 40 ns.     

The role of optimization in some recent advances in data-driven decision-making

Mathematical Programming - In this paper, we present a new framework of bi-level unconstrained minimization for development of accelerated methods in Convex Programming. These methods use...