Cost-efficient modeling of distributed molar mass and topological variations in graft copolymer synthesis by upgrading the method of moments

Cost-efficient deterministic method of moments solvers, as widely used to calculate average characteristics of chemical processes driven by population variations (e.g., average chain lengths), can be a posteriori extended with approximated solutions delivering distributed properties (e.g., chain length distributions). However, these solutions are rarely verified, specifically for complex systems with many population members and strong coupling, as is the case for industrially relevant free-radical-induced grafting (FRIG) toward graft copolymer (GC) synthesis with monomer unit dependent reactions. FRIG, as studied in the present work with polybutadiene at low styrene conversions, is an important chemical process, for example, the production of compatibilizers and high-impact materials. Deterministic model validation is uniquely performed by benchmarking the low to medium molar mass (MM) results (29 topologies) in the log-molar mass distribution with detailed matrix-based kinetic Monte Carlo simulation output, inherently capable of mapping distributions. The GC product is identified to be a heterogeneous mixture in MM, chemical composition, and molecular topology at any styrene conversion. The molecular structural evolution during GC synthesis is further theoretically related to both one-dimensional size-exclusion chromatography (1D-SEC) and two-dimensional liquid chromatography (2D-LC) analysis. It is shown that conventional SEC—even in the absence of broadening—is insufficient for GC separation, mainly due to the unavoidable coelution of topologically different GC species. In any case, the parallel running of advanced modeling tools allows for detailed molecular interpretation.     

Über die Bestimmung des Zirkoniums in hochlegierten Stählen

Übersicht über die im Schrifttum aufgeführten Verfahren zur Zirkoniumbestimmung und deren Schwierigkeiten. Nacharbeitung der photometrischen Bestimmung mit Arsenazo III und Einsatz bei hohen Legierungsgehalten. Anwendung des Verfahrens auf geringere Zirkoniumgehalte ohne Vortrennung.     

Nanoscale copper sulfide hollow spheres with phase-engineered composition: covellite (CuS), digenite (Cu1.8S), chalcocite (Cu2S)

Covellite (CuS), digenite (Cu(1.8)S) and chalcocite (Cu(2)S) are prepared as nanoscaled hollow spheres by reaction at the liquid-to-liquid phase boundary of a w/o-microemulsion. According to electron microscopy (SEM, STEM, TEM, HRTEM) the hollow spheres exhibit an outer diameter of 32-36 nm, a wall thickness of 8-12 nm and an inner cavity of 8-16 nm in diameter. The phase composition is determined based on HRTEM, electron-energy loss spectroscopy, X-ray powder diffraction and thermal analysis. In face of the advanced morphology of the hollow spheres, precise control of its phase composition is nevertheless possible by adjusting the experimental conditions (i.e. type and concentration of the copper precursor, concentration of ammonia inside of the micelle). Such phase-engineering of nanoscale hollow spheres is firstly observed and might allow adjusting even further compositions/structures as well as tailoring of phase-specific properties in the future.     

Hydrophilic Interaction Liquid Chromatography: ESI–MS/MS of Plasmalogen Phospholipids from <Emphasis Type="Italic">Pectinatus</Emphasis> Bacterium

Liquid chromatography–electrospray tandem mass spectrometry (LC/ESI–MS/MS) was used to analyze phospholipids from three species of the anaerobic beer-spoilage bacterial genus Pectinatus. Analysis of total lipids by HILIC (Hydrophilic Interaction Liquid Chromatography) column succeeded in separating diacyl- and plasmalogen phospholipids. Plasmalogens were then analyzed by means of the ESI–MS/MS and more than 220 molecular species of four classes of plasmalogens (PlsCho (choline plasmalogen), PlsEtn (ethanolamine plasmalogen), PlsGro (glycerol plasmalogen), and PlsSer (serine plasmalogen)) were identified. Major molecular species were c-p19:0/15:0 PlsEtn and PlsSer, which accounted for more than 4% of the total lipids.     

Effect of water and acid–base reactants on adhesive properties of various plasticized poly(vinyl butyral) sheets

We study the changes in adhesive properties of poly(vinyl butyral) (PVB) sheets assigned for safety glass preparation. PVB sheets have been produced by various worldwide manufacturers by simple blending methods such as extrusion, thermo‐mechanical mixer processes, etc. Some samples were modified either by magnesium acetate or by oligo‐functional organic acid to either reduce the adhesion to glass or to increase it. Adhesive measurements were evaluated on the air side and the tin side of the laminated glass. The study deals with a recognition of causes of the PVB adhesion change as a function of adsorbed water content into the polymer matrix. Results describe the influence of hydroxyl group content and amount of added acid–base reactants for adhesion adjustment of every tested PVB sheet. It also describes typical adhesion fluctuation and specific adhesion bonding of PVB sheets to glass in particular conditions. The analysis evaluates the best and the worst blend combinations and their modification on the adhesion change. We focused on adhesion sensitivity to increasing water content and the amount of added adhesion modifier. This work also evaluated the critical range of water content that provides adhesion fluctuation. The evaluation of various types of PVB sheets was performed and the most stable adhesion adjustment was found. Obtained values and comparisons are very important for the PVB sheets industry and for industry dealing with lamination of laminated glasses. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Identification of Plasmalogen Cardiolipins from Pectinatus by Liquid Chromatography–High Resolution Electrospray Ionization Tandem Mass Spectrometry

High resolution electrospray ionization tandem mass spectrometry (HR-ESI–MS/MS) was used to analyze cardiolipins (Ptd₂Gro) including their plasmalogen forms from three species of the anaerobic beer-spoilage bacterial genus Pectinatus. Cardiolipins including their plasmalogens were analyzed by HR-ESI–MS/MS on Orbitrap and almost 100 cardiolipins (i.e. tetra-acyl—Ptd₂Gro, plasmenyl-tri-acyl—PlsPtd₂Gro, and di-plasmenyl-di-acyl—Pls₂Ptd₂Gro) of three classes were identified. The structures of the molecular species that consist of various regioisomers and structurally similar compounds were revealed in detail. The high resolution mass spectrometry allowed the unambiguous structural assignment of Ptd₂Gro, PlsPtd₂Gro, and Pls₂Ptd₂Gro in the three species of Pectinatus, which contain predominantly odd numbered fatty acids.     

A study of the effect of surface pre-treatment on the adhesion of coatings

This paper deals with the study of effects of mechanical surface preparation on the adhesion of coating with high content of zinc dust. Five kinds of mechanically blasted surfaces were studied. The following were used as abrasives: steel shot, steel grit, brown corundum oxide and zirblast. The last surface type was modified by MBX Blaster technology (mechanical bristle blasting). The surfaces topography was quantified by a roughness profilometer. The shape and size of the incurred inequalities on the modified surfaces were studied using 3D microscope images of the surface. The purity of the surfaces after pre-treatment was evaluated by impurity glued on the tape and measuring the reflection of light from the surface. Fractal analysis was used to evaluate the diversity of inequalities on the prepared surfaces. Cross-sections were also taken of the prepared surfaces. The prepared surfaces were coated with zinc-filled coating. The adhesion of the coating to the substrate was evaluated by a pull-off test after curing the coating (as sprayed), as well as after exposure to severe corrosive environments. The best adhesion of the coating was found for the coating applied to the substrate which had been pre-treated with brown corundum and steel grit.     

The structure of iron superoxide dismutase from Pseudomonas ovalis complexed with the inhibitor azide

The 2.9 Å resolution structure of iron superoxide dismutase(FeSOD) (EC 1.15.1.1 [EC] ) from Pseudomonas ovalis complexed withthe inhibitor azide was solved. Comparison of this structurewith free enzyme shows that the inhibitor is bound at the opencoordination position of the iron, with a bond length of 2.0Å. The metal moves by 0.4 Å into the trigonal planeto produce an orthogonal geometry at the iron. Binding of theinhibitor also causes a movement of the axial ligand (histidine26) away from the metal, a lengthening of the iron—histidinebond, and a rotation of the histidine 74 ring. The inhibitorpossesses contacts in the binding pocket with a pair of conservedtryptophan residues and with the side chains of tyrosine 34and glutamine 70. This glutamine is conserved between all FeSODs,but is absent in MnSOD. Comparisons with MnSOD show that a differentglutamine which possesses the same interactions in the activesite as Gln70 in FeSOD is conserved at position 154 in the overallSOD sequence, implying that while manganese and FeSODs are structuralhomologues in a global sense, their functional and evolutionaryrelationship is that of second-site mutation revertants.     

Piezoelectric coefficients of -alanine doped TGS crystals

Double beam laser interferometry has been used to study small displacement of LATGS crystals caused by the converse piezoelectric effect. All eight nonzero mutually independent piezoelectric coefficients d_iλ have been derived. The temperature dependence of the piezoelectric coefficient d₂₂ has been measured using the single beam Michelson interferometer. The phase transition temperature was determined near 324 K.