Structural testing and numerical simulation of a 34 m composite wind turbine blade

A full-scale 34 m composite wind turbine blade was tested to failure under flap-wise loading. Local displacement measurement equipment was developed and displacements were recorded throughout the loading history.

Ovalization of the load carrying box girder was measured in the full-scale test and simulated in non-linear FE-calculations. The nonlinear Brazier effect is characterized by a crushing pressure which causes the ovalization. To capture this effect, non-linear FE-analyses at different scales were employed. A global non-linear FE-model of the entire blade was prepared and the boundaries to a more detailed sub-model were extracted. The FE-model was calibrated based on full-scale test measurements.

Local displacement measurements helped identify the location of failure initiation which lead to catastrophic failure. Comparisons between measurements and FE-simulations showed that delamination of the outer skin was the initial failure mechanism followed by delamnination buckling which then led to collapse. 

Microbiota of De-Novo Pediatric IBD: Increased Faecalibacterium Prausnitzii and Reduced Bacterial Diversity in Crohn's But Not in Ulcerative Colitis

OBJECTIVES: The gastrointestinal microbiota is considered important in inflammatory bowel disease (IBD) pathogenesis. Discoveries from established disease cohorts report reduced bacterial diversity, changes in bacterial composition, and a protective role for Faecalibacterium prausnitzii in Crohn's disease (CD). The majority of studies to date are however potentially confounded by the effect of treatment and a reliance on established rather than de-novo disease.

METHODS: Microbial changes at diagnosis were examined by biopsying the colonic mucosa of 37 children: 25 with newly presenting, untreated IBD with active colitis (13 CD and 12 ulcerative colitis (UC)), and 12 pediatric controls with a macroscopically and microscopically normal colon. We utilized a dual-methodology approach with pyrosequencing (threshold >10,000 reads) and confirmatory real-time PCR (RT-PCR).

RESULTS: Threshold pyrosequencing output was obtained on 34 subjects (11 CD, 11 UC, 12 controls). No significant changes were noted at phylum level among the Bacteroidetes, Firmicutes, or Proteobacteria. A significant reduction in bacterial alpha-diversity was noted in CD vs. controls by three methods (Shannon, Simpson, and phylogenetic diversity) but not in UC vs. controls. An increase in Faecalibacterium was observed in CD compared with controls by pyrosequencing (mean 16.7% vs. 9.1% of reads, P = 0.02) and replicated by specific F. prausnitzii RT-PCR (36.0% vs. 19.0% of total bacteria, P = 0.02). No disease-specific clustering was evident on principal components analysis.

CONCLUSIONS: Our results offer a comprehensive examination of the IBD mucosal microbiota at diagnosis, unaffected by therapeutic confounders or changes over time. Our results challenge the current model of a protective role for F. prausnitzii in CD, suggesting a more dynamic role for this organism than previously described.

Evaluation of in Situ DGT Measurements for Predicting the Concentration of Cd in Chinese Field-Cultivated Rice: Impact of Soil Cd:Zn Ratios

DGT (diffusive gradients in thin-films) has been proposed as a tool for predicting Cd concentrations in rice grain, but there is a lack of authenticating data. To further explore the relationship between DGT measured Cd and concentrations in rice cultivated in challenging, metal degraded, field locations with different heavy metal pollutant sources, 77 paired soil and grain samples were collected in Southern China from industrial zones, a "cancer village" impacted by mining waste and an organic farm. In situ deployments of DGT in flooded paddy rice rhizospheres were compared with a laboratory DGT assay on dried and rewetted soil. Total soil concentrations were a very poor predictor of plant uptake. Laboratory and field deployed DGT assays and porewater measurements were linearly related to grain concentrations in all but the most contaminated samples where plant toxicity occurred. The laboratory DGT assay was the best predictor of grain Cd concentrations, accommodating differences in soil Cd, pollutant source, and Cd:Zn ratios. Field DGT measurements showed that Zn availability in the flooded rice rhizospheres was greatly diminished compared to that of Cd, resulting in very high Cd:Zn ratios (0.1) compared to commonly observed values (0.005). These results demonstrate the potential of the DGT technique to predict Cd concentrations in field cultivated rice and demonstrate its robustness in a range of environments. Although, field deployments provided important details about in situ element stoichiometry, due to the inherent heterogeneity of the rice rhizosphere soils, deployment of DGT in dried and homogenized soils offers the best possibility of a soil screening tool.

Self-Assembled Supramolecular Gels of Reverse Poloxamers and Cyclodextrins

A series of supramolecular aggregates were prepared using a poly(propylene oxide) poly(ethylene oxide) poly(propylene oxide) (PPO-PEO-PPO) block copolymer and beta- or alpha-cyclodextrins (CD). The combination of beta-CD and the copolymer yields inclusion complexes (IC) with polypseudorotaxane structures. These are formed by complexation of the PPO blocks with beta-CD molecules producing a powder precipitate with a certain crystallinity degree that can be evaluated by X-ray diffraction (XRD). In contrast, when combining alpha-CD with the block copolymer, the observed effect is an increase in the viscosity of the mixtures, yielding fluid gels. Two cooperative effects come into play: the complexation of PEO blocks with alpha-CD and the hydrophobic interactions between PPO blocks in aqueous media. These two combined interactions lead to the formation of a macromoleculaf network. The resulting fluid gels were characterized using different techniques such as differential scanning calorimetry (DSC), viscometry, and XRD measurements.

Fragmentation of CD+ induced by intense ultrashort laser pulses

The fragmentation of CD+ in intense ultrashort laser pulses was investigated using a coincidence three-dimensional momentum imaging technique improved by employing both transverse and longitudinal electric fields. This allowed clear separation of all fragmentation channels and the determination of the kinetic energy release down to nearly zero, for a molecule with significant mass asymmetry. The most probable dissociation pathways for the two lowest dissociation limits, C+ + D and C+ D+, were identified for both 22-fs, 798-nm and 50-fs, 392-nm pulses. Curiously, the charge asymmetric dissociation of CD2+ was not observed for 392-nm photons, even though it was clearly visible for the fundamental 798 nm at the same peak intensity.

Sensitivity to Cd or Zn of host and symbiont of ectomycorrhizal Pinus sylvestris L. (Scots pine) seedlings

Pinus sylvestris seedlings infected with either the ectomycorrhizal (ECM) fungus Paxillus involutus or Suillus variegatus were exposed to a range of Cd or Zn concentrations. This was done to investigate the relationship between the sensitivity of ECM fungi and their host plants over a wide range of concentrations. P involutus ameliorated the toxicity of Cd and Zn to P. sylvestris with respect to root length, despite significant inhibition of ECM infection levels by Cd (Cd EC₅₀ [effective concentration which inhibits ECM infection by 50%] values were: P. involutus 3.7 μg g^-1 Cd; S. variegatus 2.3 μg g^-1 Cd). ECM infection by P. involutus also decreased Cd and Zn transport to the plant shoots at potentially toxic concentrations and also influenced the proportion of Zn transported to the roots and shoots, with a higher proportion retained in the roots of the seedlings. ECM infection did increase host biomass production, but this was not affected by the presence of Cd or Zn. Root and shoot biomass production by P. sylvestris, in both the presence and absence of ECM fungi, was unaffected by Cd and Zn at all concentrations tested.

Cross-colonization of scots pine (Pinus sylvestris) seedlings by the ectomycorrhizal fungus Paxillus involutus in the presence of inhibitory levels of Cd and Zn

The effects of Cd and Zn on cross-colonization by Paxillus involutus of Scots pine seedlings was examined by using pairs of ectomycorrhizal (ECM) and non-mycorrhizal (NM) seedlings grown in the same vessel. This was done to assess, first, the ability of P. involutus to colonize NM Scots pine seedlings by growth from colonized roots of other Scots pine seedlings in the presence of Cd or Zn, and, second whether ECM colonization of Scots pine by P. involutus provided a competitive advantage over NM seedlings. Ectomycorrhizal colonization of Scots pine was shown to be more sensitive than Scots pine itself to Cd and Zn, but prior colonization did provide a competitive advantage with respect to biomass production. This beneficial effect over NM seedlings was, however, equal in the control, Cd and Zn treatments, and was due simply to growth stimulation in the presence of ECM colonization. Cross-colonization from an ECM to a NM seedling was reduced but not prevented by Cd and Zn. Cd had a more negative effect on cross-colonization than on initial colonization of seedlings, whereas Zn had an equally inhibitory effect on both parameters. These results have important implications for plant establishment on metal-contaminated sites. If cross-colonization between plants is reduced by toxic metals, plant establishment on contaminated sites might be retarded.