Anatomy of terminal moraine segments and implied lake stability on Ngozumpa Glacier, Nepal, from electrical resistivity tomography (ERT)

This research was supported financially by the European Commission FP7-MC-IEF (PIEF-GA-2012-330805), the University Centre in Svalbard (UNIS), National Geographic Society GRANT #W135-10.Moraine-dammed lakes at debris-covered glaciers are becoming increasingly common and pose significant outburst flood hazards if the dam is breached. While moraine subsurface structure and internal processes are likely to influence dam stability, only few sites have so far been investigated. We conducted electrical resistivity tomography (ERT) surveys at two sites on the terminal moraine complex of the Ngozumpa Glacier, Nepal, to aid assessment of future terminus stability. The resistivity signature of glacier ice at the site (100-15 kΩ m) is more consistent with values measured from cold glacier ice and while this may be feasible, uncertainties in the data inversion introduce ambiguity to this thermal interpretation. However, the ERT data does provide a significant improvement to our knowledge of the subsurface characteristics at these sites, clearly showing the presence (or absence) of glacier ice. Our interpretation is that of a highly complex latero-terminal moraine, resulting from interaction between previous glacier advance, recession and outburst flooding. If the base-level Spillway Lake continues to expand to a fully formed moraine-dammed glacial lake, the degradation of the ice core could have implications for glacial lake outburst risk.Publisher PDFPeer reviewe

Micromechanical Properties of Injection-Molded Starch–Wood Particle Composites

The micromechanical properties of injection molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X-ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition,creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection-molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples.Peer reviewe

Optimal duration of ex vivo lung perfusion for heat stress-mediated therapeutic reconditioning of damaged rat donor lungs.

Transient heat stress (HS) application during experimental ex vivo lung perfusion (EVLP) of warm ischaemic (WI) rat lungs produces a range of therapeutic benefits. Here, we explored whether different EVLP durations after HS application would influence its therapeutic effects. In protocol 1, WI rat lungs were exposed to HS (41.5°C, 60-90 min EVLP), and EVLP was maintained for 3, 4.5 or 6 h (n = 5/group), followed by physiological measurements (compliance, oedema, oxygenation capacity). In protocol 2, WI rat lungs treated with (HS groups) or without HS (control groups) were maintained for 3 or 4.5 h EVLP (n = 5/group), followed by physiological evaluation and measurements (lung tissue) of heat shock proteins (HSP70, HSP27, HS90, GRP78), endogenous proteins (surfactant protein-D, CC16, platelet endothelial cell adhesion molecule-1), anti-apoptotic (Bcl2, Bcl-xL) and pro-apoptotic proteins (Bcl2-associated X protein, CCAAT/enhancer binding-protein homologous protein), antioxidant enzymes (heme-oxygenase-1, nicotinamide di-phospho-nucleotide dehydrogenase quinone-1) and nitrotyrosine (oxidative stress biomarker). In protocol 1, physiological variables were stable after 3 and 4.5 h but deteriorated after 6 h. In protocol 2, at 3 h EVLP, HS-treated lungs differed from controls by higher expression of HSP70 and heme-oxygenase-1, and lower CC16 expression. In contrast, at 4.5 h EVLP, HS-treated lungs displayed improved physiology, higher levels of all HSPs, preserved or increased expression of surfactant protein-D, CC-16 and platelet endothelial cell adhesion molecule-1, increased antioxidant and anti-apoptotic proteins, and reduced pro-apoptotic proteins and nitrotyrosine. The protective effects of HS application during EVLP of WI-damaged rat lungs strictly depend on the duration of post-HS recovery. An EVLP duration of 4.5 h appears to optimize the therapeutic potential of HS, while maintaining lungs in a stable physiological state

To what extent is the description of streets important in estimating local air quality: a case study over Paris

Modeling atmospheric composition at street level is challenging because pollutant concentrations within street canyons depend on both local emissions and the transport of polluted air masses from remote areas. Therefore, regional-scale modeling and local applications must be combined to provide accurate simulations of the atmospheric composition at street locations. In our study, we compare two strategies: (i) a subgrid-scale approach embedded in the chemistry–transport model (denoted Subgrid) and (ii) the street-network model MUNICH (Model of Urban Network of Intersecting Canyons and Highways). In both cases, the regional-scale chemistry–transport model CHIMERE provides the urban background concentrations, and the meteorological model Weather Research and Forecasting (WRF), coupled with CHIMERE, is used to provide meteorological fields. Simulation results for NOx, NO2, and PM2.5 concentrations over the city of Paris from both modeling approaches are compared with in situ measurements from traffic air quality stations. At stations located in downtown areas, with low traffic emissions, the street-network model MUNICH exhibits superior performance compared to the Subgrid approach for NOx concentrations, while comparable results are obtained for NO2. However, significant discrepancies between the two methods are observed for all analyzed pollutants at stations heavily influenced by road traffic. These stations are typically located near highways, where the difference between the two approaches can reach 58 %. The ability of the Subgrid approach to estimate accurate emission data is limited, leading to potential underestimation or overestimation of gas and fine-particle concentrations based on the emission heterogeneity it handles. The performance of MUNICH appears to be highly sensitive to the friction velocity, a parameter influenced by the anthropogenic heat flux used in the WRF model. Street dimensions do contribute to the performance disparities observed between the two approaches, yet emissions remain the predominant factor.</p