Blends of thermoplastic polyurethane and maleic-anhydride grafted polyethylene. I: Morphology and mechanical properties

Thermoplastic polyurethane elastomers (TPU) and polyethylene (PE) form immiscible blends with an extremely low compatibility. In order to improve the dispersion, stability, and properties of these blends, polyethylene was grafted with maleic anhydride (PE-g-MA). Subsequently, it was blended with a commercial polyester - type TPU in a twin-screw extruder. With PE-g-MA as blend component, the particle size was dramatically reduced in comparison with PE. Coalescence was significantly reduced and the increase in particle size with composition was less pronounced than in blends with PE. In addition, the phase adhesion and the mechanical properties were improved by using PE-g-MA as minor component. Grafting of the MA onto the PE leads to a decrease of the molecular weight, the melt viscosity, and the mechanical properties of the pure PE. Hence, the reactive blend system exhibits a lower viscosity ratio. Comparison of these results with those from uncompatibilized blends with different viscosity ratios revealed that the reduction in viscosity ratio has a big influence on the blend morphology and because of that on the mechanical properties. In addition, there is a further effect on morphology and properties caused by the reduction in interfacial tension, which results from the compatibilizer formed at the interface.     

Oxygen evolution during the formation and sintering of nickel-manganese oxide spinels for thermistor applications

Nickel-manganese spinel, prepared from 20 wt % NiO and 80 wt % Mn₂O₃, forms at 950°C by the intermediate formation of Mn₃O₄ with evolution of oxygen, determined by mass-spectrometric evolved gas analysis. On heating to higher temperatures, further oxygen is evolved resulting in pore formation and bloating of pressed sintered samples and anomalies in their densification and electrical properties. Thermodynamic considerations and X-ray diffraction intensity measurements suggest that all the Mn²⁺ is located in the tetrahedral spinel sites, this cation configuration remaining unchanged by higher-temperature treatments such as sintering.     

Adaptive Immune Responses in a Multiple Sclerosis Patient with Acute Varicella-Zoster Virus Reactivation during Treatment with Fingolimod

Fingolimod, an oral sphingosine 1-phosphate (S1P) receptor modulator, is approved for the treatment of relapsing forms of multiple sclerosis (MS). The interference with S1P signaling leads to retention particularly of chemokine receptor-7 (CCR7) expressing T cells in lymph nodes. The immunological basis of varicella zoster virus (VZV) infections during fingolimod treatment is unclear. Here, we studied the dynamics of systemic and intrathecal immune responses associated with symptomatic VZV reactivation including cessation of fingolimod and initiation of antiviral therapy. Key features in peripheral blood were an about two-fold increase of VZV-specific IgG at diagnosis of VZV reactivation as compared to the previous months, a relative enrichment of effector CD4+ T cells (36% versus mean 12% in controls), and an accelerated reconstitution of absolute lymphocytes counts including a normalized CD4+/CD8+ ratio and reappearance of CCR7+ T cells. In cerebrospinal fluid (CSF) the lymphocytic pleocytosis and CD4+/CD8+ ratios at diagnosis of reactivation and after nine days of fingolimod discontinuation remained unchanged. During this time CCR7+ T cells were not observed in CSF. Further research into fingolimod-associated VZV reactivation and immune reconstitution is mandatory to prevent morbidity and mortality associated with this potentially life-threatening condition.     

Tagging Glycoproteins with Fluorescently Labeled GDP‐Fucoses by Using α1,3‐Fucosyltransferases

Fucose‐containing glycans mediate a variety of biological processes, but there is little information on reaction processes and mechanisms mediated by fucosyltransferases. We recently reported on fluorescently labeled GDP‐β‐L ‐fucose‐ATTO 550, which enabled monitoring of α1,3‐fucosyltransferase activity. Here we present an extension to the previously described results, based on the synthesis of a fluorescein‐isothiocyanate (FITC)‐labeled and two carboxyfluorescein‐labeled (FAM‐labeled) NDP‐β‐L ‐fucose derivatives, and applied all four compounds in labeling of different glycoproteins with the aid of four different fucosyltransferases. The labeling processes were analyzed by in‐gel fluorescence and fluorescence polarization measurements. Comparison with the ATTO‐labeled sugar revealed that the FITC‐labeled fucose was the best of these substrates, and that the bacterial enzyme HP‐FucT tolerated the fluorescent substrates better than human fucosyltransferases.     

Begrenzung der Rissbreite nach Eurocode 2

Crack width control according to Eurocode 2 – Explanatory notes on factor k _c Reinforced concrete members are designed now according to EC2 [1]. A significant aspect is the determining of the minimum reinforcement area specified in section 7.3.2. Due to the shortened illustrations of the equations (7.1) and (7.2), the mechanical background is difficult to be highlighted. This often results in inaccurate use of the model parameters, which might lead to an unsafe design, particularly for members predominantly reinforced only by the minimum reinforcement. Therefore the mechanical background of the equations (7.1) and (7.2) is focused on in this contribution. Proper discussions and explanations might help the structural engineer in the practical design.     

A comparison of PCB bioaccumulation factors between an arctic and a temperate marine food web

To test how environmental conditions in the Arctic and the resulting ecological adaptations affect accumulation of persistent organic pollutants (POPs) in the marine food web, bioaccumulation of four polychlorinated biphenyls (PCBs) in an arctic (Barents Sea 77 °N-82 °N) and a temperate marine (Baltic Sea 54 °N-62 °N) food web were compared. Three different trophic levels were studied (zooplankton, fish, and seal), representing the span from first-level consumer to top predator. Previously published high-quality data on PCB water concentrations in the two areas were used for calculation of bioaccumulation factors (BAF). BAF was calculated as the ratio of the PCB concentration in the organism ([PCB]_org; pg/kg lipid) to the dissolved water concentration (C_w; pg/L). The BAF_Arctic:BAF_Temperate ratios were above 1 for all four PCB congeners in zooplankton (6.4-13.8) and planktivorous fish (2.9-5.0)), whereas the ratios were below 1 in seal. The mean ratio between arctic and temperate BAFs for all trophic levels and congeners (BAF_Arcti:BAF_Temperate) was 4.8. When the data were corrected for the seawater temperature difference between the two ecosystems, the ratio was 2.0. We conclude that bioaccumulation differences caused by ecological or physiological adaptations of organisms between the two ecosystems were well within a water concentration variability of 50%. Further, our data support the hypothesis that lower seawater temperature lead to a thermodynamically favoured passive partitioning to organic matrices and thus elevated ambient BAFs in the Arctic compared to the Baltic Sea. This would imply that bioaccumulation in the Arctic may be described in the same way as bioaccumulation in temperate regions, e.g. by the use of mechanistic models parameterised for the Arctic.     

Efficiency improvement of dye-sensitized solar cells based on electrodeposited TiO2 films by low temperature post-treatment

Porous crystalline TiO₂ films can be prepared at low temperatures (80 °C) by surfactant-assisted electrodeposition from TiCl₃ solution. Nevertheless, up to now calcination at high temperatures (typically 450 °C) was still necessary to establish a good performance of these films in dye-sensitized solar cells (DSSC). With this study we report that water vapour treatment at much lower temperatures (150 °C) for 1 week improves the performance of the films in DSSC to the same degree as calcination although the overall crystallinity remains lower. Reason for the good efficiency is that the porous structure stays intact and thus the dye molecules can be better adsorbed. Avoiding high temperatures during the preparation process of TiO₂ films for the application in DSSC enables the use of polymer substrates for the fabrication of flexible solar cells.     

Intra-storm variability in microbial partitioning and microbial loading rates

Association with particles in the water column can have a significant impact on microbial fate and transport. This study analyzed multiple stormwater samples taken throughout the duration of three separate storms (at two different sites) to evaluate the fraction of microbes partitioning to denser "settleable" particles and to examine how partitioning behavior varied over the course of a storm. Intra-storm sampling also allowed for estimates of microbial loading rates (both total and particle-associated) and cumulative storm-induced microbial load. Five different indicator organisms were examined, with the fraction of microbes associated with settleable particles assessed via a calibrated centrifugation method. Partitioning behavior varied across microorganism type, with an average of 40% of fecal coliforms, Escherichia coli, and enterococci associating with settleable particles, compared to approximately 65% of Clostridium perfringens spores and only 13% of total coliphage. Partitioning remained fairly constant for each type of organism throughout storm events. Nonetheless, higher concentrations of both settleable particles and microbes entering the water column soon after the onset of a storm led to higher loading rates of settleable microbes in the storm's earliest stages, a trend that could have important implications for the design of stormwater management structures (e.g., detention basins). Estimates of cumulative storm-induced microbial loading suggested that one day's worth of storm loading can be the equivalent of months, or even years, of dry-weather loading.