Sintered Halon as a diffuse reflecting liner for light integration boxes

Sintered Halon G-80, a polytetrafluoroethylene (PTFE) resin available commercially in powdered form, is a superb diffuse reflector. Sintered Halon has 96% absolute reflectance at wavelengths between 300 nm and 380 nm, and about 98% absolute reflectance above 380 nm. It is chemically inert, is mechanically strong, does not fluoresce, and the high reflectance is easy to maintain over time. We have used sintered Halon as a lining in light integration boxes of water Cherenkov detectors. Preparation involves packing Halon powder into a mold to a specific density, then heating the material almost to the melting point (sintering). A method of preparing sintered Halon is presented. Physical properties of sintered Halon have been measured and we present those results here as well.     

Surface topography and tribological properties of coatings prepared from microparticle size polyurethane dispersions studied by atomic force microscopy

The surface topography and mechanical properties of coatings prepared using large particle size polyurethane dispersions (PUD) are investigated using atomic force microscopy (AFM) imaging, AFM-based force measurements, and friction force microscopy. PUD coatings, which are prepared from dispersions containing particles of micron size, have surface roughness of 250–300 nm and waviness of 2.5–3 μm resulting from the particle size. The surface moduli of the PUD coatings are varied by tuning the ratio of hard-to-soft segmentation in the polyurethanes and are found to be between 40 and 100 MPa. The friction coefficient obtained in the study is found to be correlated with both the surface modulus of the coatings and the adhesion between the probe and the samples and is well in line with the perceived feel of an experienced human panel. The data are very well behaved and clearly show the utility of this technique in characterizing these types of surfaces.     

ESBL-producing E. coli in Austrian sewage sludge

The aim of this study was to investigate the degree of contamination of sewage sludge with ESBL-producing Escherichia coli strains and the effectiveness of different sewage sludge treatment methods.Monthly sewage sludge samples were collected between January and September 2009 in 5 different sewage treatment plants and tested for the presence of ESBL E. coli. In addition, the number of colony forming units (CFU) of E. coli and coliform bacteria before and after the different sludge treatment methods (aerobic/anaerobic digestion, lime stabilization, and thermal treatment) was investigated.Of the 72 sewage sludge samples investigated, ESBL-positive E. coli were found in 44 (61.1%) sewage sludge samples. The classification of β-lactamase groups was carried out in 15 strains resulting in the detection of 2 different groups (CTX-M and TEM) of bla genes. All 15 of them had a CTX-M gene and 4 of these strains furthermore carried a TEM gene.With regard to the CFU of E. coli and coliform bacteria, thermal treatment and lime stabilization following dehydration sufficiently reduced pathogen concentrations. The plants using merely stabilization and dehydration showed an increase of E. coli and coliform bacteria and thus also an increase in ESBL-producing E. coli.     

Influence of Impact on the Mechanical Behaviour of the Gamma‐Based TiAl Alloy TNBV3B

The quasi‐static and fatigue behavior after impact of the TiAl alloy TNBV3B produced via three different processing routes—cast, forged and extruded—has been studied on flat and airfoil‐like shaped specimens making use of ballistic impact experiments. For impacts resulting in cracks the behavior can be described using a linear‐elastic fracture mechanics approach. The residual strength is described on the basis of the fracture toughness. The residual fatigue strength of impact‐cracked specimens is estimated on the basis of the threshold for crack growth of the TNBV3B alloys. However, when there is no visible crack or when the crack length is below the size of the deformed impact area, residual stresses and micro‐damage play a dominating role making the linear‐elastic fracture mechanics approach invalid. The deformation hardened zone in TiAl has been studied making use of micro‐hardness tests showing their extension and the degrees of deformation for different impact energies.     

Catalytic conditioning of synthesis gas produced by biomass gasification

The catalytic steam reforming of aromatic hydrocarbons in a background of synthesis gas was investigated for two catalysts. A proprietary non-nickel based catalyst, designated DN-34, and a commercial nickel steam reforming catalyst ICI 46-1 were tested. Statistically designed experiments were used to examine the effects of temperature, space velocity and percent of steam in the feed on catalyst performance. All experiments were performed in a plug-flow micro-reactor interfaced with a molecular beam mass spectrometer. The catalyst DN-34 was also tested in slip-stream fluidized bed reactors attached to a 9 tonne day⁻¹ indirectly heated biomass gasifier at Battelle Columbus Laboratory.

DN-34 was found to be effective for destroying a variety of aromatic hydrocarbons found in biomass gasifier tar in both the micro-reactor and gasifier-scale experiments. DN-34 also exhibited significant water-gas shift activity but was unsatisfactory for methane destruction. ICI 46-1 exhibited excellent methane steam reforming activity. A process is suggested that uses DN-34 to steam reform tar and perform the water-gas shift, followed by a second reactor with ICI 46-1 to reform methane. Differences and similarities with other dual-bed processes described in the literature are discussed.     

Umsetzung von Dihydroxyaceton mit Methylammoniumacetat Untersuchungen zur Maillard-Reaktion, X

Zusammenfassung Dihydroxyaceton reagiert mit Methylammoniumacetat in wäßriger Lösung beim Erhitzen rasch unter Bräunung. Von den mit Methylenchlorid extrahierbaren Produkten konnten die heterocyclischen Verbindungen 1 bis 30 isoliert und größtenteils identifiziert werden.

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Reaction of dihydroxyacetone with methylammoniumacetate studies on the Maillard-Reaction, X

Summary By heating dihydroxyacetone and methylammoniumacetate in aqueous solution, a deeply brown coloured reaction mixture is obtained. The products extractable with methylenechlorid were separated. Several heterocyclic compounds (1–30) could be identified.