Mussel Byssal Attachment Weakened by Anthropogenic Noise

The increasing underwater noise generated by anthropogenic activities has been widely recognized as a significant and pervasive pollution in the marine environment. Marine mussels are a family of sessile bivalves that attach to solid surfaces via the byssal threads. They are widely distributed along worldwide coastal areas and are of great ecological and socio-economic importance. Studies found that anthropogenic noise negatively affected many biological processes and/or functions of marine organisms. However, to date, the potential impacts of anthropogenic noise on mussel byssal attachment remain unknown. Here, the thick shell mussels Mytilus coruscus were exposed to an ambient underwater condition (∼50 dB re 1 μPa) or the playbacks of pile-driving noise (∼70 or ∼100 dB re 1 μPa) for 10 days. Results showed that the noise significantly reduced the secretion of byssal threads (e.g., diameter and volume) and weakened their mechanical performances (e.g., strength, extensibility, breaking stress, toughness and failure location), leading to a 16.95–44.50% decrease in mussel byssal attachment strength. The noise also significantly down-regulated the genes expressions of seven structural proteins (e.g., mfp-1, mfp-2, mfp-3, mfp-6, preCOL-P, preCOL-NG, and preCOL-D) of byssal threads, probably mediating the weakened byssal attachment. Given the essential functions of strong byssal attachment, the findings demonstrate that the increasing underwater anthropogenic noise are posing a great threat to mussel population, mussel-bed community and mussel aquaculture industry. We thus suggest that future work is required to deepen our understanding of the impacts of anthropogenic noise on marine invertebrates, especially these with limited locomotion ability, like bivalves.

Influence of pallet pattern on top-to-bottom compression performance of unitized loads

Environmental scaling factors estimate a corrugated container’s ability to withstand various conditions it will encounter during the storage and distribution process. In this project, we examined the compressive resistance of unitized loads using differing pallet stacking patterns. To simulate real-world failure scenarios in our laboratory tests, we used two different nominal board grades of single-wall C-flute regular slotted containers loaded with a plywood panel and bagged salt to direct the failure location to the bottom of the stack. Our results showed that the columnar aligned pattern provided the greatest compressive resistance and the interlocked stacking arrangement yielded the lowest of the patterns evaluated. Based on the study results, we calculated box compression retention multipliers for each pattern and compared them to scaling factors published by the Fibre Box Association.

Cross-Sectional Geometry Predicts Failure Location in Maize Stalks

Background: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Stalk lodging occurs when high winds induce bending moments in the stalk which exceed the bending strength of the plant. Previous biomechanical models of plant stalks have investigated the effect of cross-sectional morphology on stalk lodging resistance (e.g., diameter and rind thickness). However, it is unclear if the location of stalk failure along the length of stem is determined by morphological or compositional factors. It is also unclear if the crops are structurally optimized, i.e., if the plants allocate structural biomass to create uniform and minimal bending stresses in the plant tissues. The purpose of this paper is twofold: (1) to investigate the relationship between bending stress and failure location of maize stalks, and (2) to investigate the potential of phenotyping for internode-level bending stresses to assess lodging resistance. Results: 868 maize specimens representing 16 maize hybrids were successfully tested in bending to failure. Internode morphology was measured, and bending stresses were calculated. It was found that bending stress is highly and positively associated with failure location. A user-friendly computational tool is presented to help plant breeders in phenotyping for internode-level bending stress. Phenotyping for internode-level bending stresses could potentially be used to breed for more biomechanically optimal stalks that are resistant to stalk lodging. Conclusions: Internode-level bending stress plays a potentially critical role in the structural integrity of plant stems. Equations and tools provided herein enable researchers to account for this phenotype, which has the potential to increase the bending strength of plants without increasing overall structural biomass.

Investigating the impact of local wind conditions on Toronto's glass balcony guard failures

An investigative study was performed on the Shangri-La Hotel in Toronto in order to determine the impact of local wind conditions on the glass balcony guard failures seen in Toronto in the last five years. An accurate CFD simulation model was developed for external flow applications through a wind tunnel validation study. The simulation was used to analyze average wind conditions and extreme (gust) wind conditions at the balcony guard failure locations, as well as identify potential areas of concern on the Shangri-La Hotel. A strong correlation between failure location and common wind conditions was established, however it was concluded that wind loading was likely not the primary cause of failure.

Investigating the impact of local wind conditions on Toronto's glass balcony guard failures

An investigative study was performed on the Shangri-La Hotel in Toronto in order to determine the impact of local wind conditions on the glass balcony guard failures seen in Toronto in the last five years. An accurate CFD simulation model was developed for external flow applications through a wind tunnel validation study. The simulation was used to analyze average wind conditions and extreme (gust) wind conditions at the balcony guard failure locations, as well as identify potential areas of concern on the Shangri-La Hotel. A strong correlation between failure location and common wind conditions was established, however it was concluded that wind loading was likely not the primary cause of failure.

Root age influences failure location in grass species during mechanical testing

Aims Root tensile tests are often rejected if failure location is outside the middle section of samples. This study aims to identify where and why failure occurs along a root axis, and hence to revisit current approaches to test-validity. Methods Roots from Festuca arundinacea; Lolium multiflorum; Lolium perenne were sampled from field-grown plants. Roots were tensile tested using a universal testing machine. Root samples were randomly allocated into two groups for testing. Group 1 roots were orientated with the older tissue closest to the top clamp, group 2 roots were orientated oppositely. Tensile strength, Young’s modulus and failure location were recorded for each sample. Results Lolium multiflorum roots were thinner and stronger than roots of Festuca arundinacea. Failure location in tensile tests depended significantly on tissue age with 75% of samples failing in the younger third of root tissue regardless of the root orientation in the testing frame. Only 7% of roots failed in the middle third of the sample. Conclusions Fibrous roots tested in tension were observed to consistently fail in the younger tissue along the root axis. Exclusion of samples which fail outside the middle region of the root axis needs re-evaluation for a range of species.