Experimental Study on Behavior of Shear Connectors Embedded in Steel-Reinforced Concrete Joints

[EN] This paper presents an experimental study on the behavior of shear connectors embedded in steel-reinforced concrete joints. In steel-reinforced concrete joints, the shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. Further, in Japan, some studies in recently have also been undertaken to apply perfobond rib shear connector (PBL), which is a type of shear connectors developed in civil engineering, to the steel-reinforced concrete joints in building structures. To clarify the influence of the arrangement methods of headed studs and PBLs to reinforced concrete member on the joints, T-shaped subassembrages were tested under the monotonic tensil loading.This experiment is constituted of the following; Exp. I: Bond strength across the steel-concrete interface. Exp. II: Arrangement methods of these shear connectors to reinforced concrete member. The following can be drawn from the test results 1) The experimental values of the average maximum and residual bond strength are 0.230-0.280 and 0.15-0.18 N/mm2, respectively. 2) When the distance of between the upper surface of the reinforced concrete member from the first layer for headed studs are small, the failure mode of the specimens is similar to a concrete-cone type failure. 3) In case that the total number of headed studs or the hole provided to PBL is the same, the maximum load of the specimen with the parallel arrangement is larger than that of when shear connecters are vertically arranged. 4) The shear strength of headed studs in the joints embedded the steel member in the reinforced concrete member is estimated by superposing the average residual bond strength across the steel-concrete interface.Nakamori, R.; Kageyama, Y.; Baba, N. (2018). Experimental Study on Behavior of Shear Connectors Embedded in Steel-Reinforced Concrete Joints. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 527-532. https://doi.org/10.4995/ASCCS2018.2018.7124OCS52753

Interaction network rewiring and species’ contributions to community-scale flexibility

「やわらかい」ネットワークを作るコア生物種 --生態系の柔軟性を支える種を探索する--. 京都大学プレスリリース. 2024-03-07.The architecture of species interaction networks is a key factor determining the stability of ecological communities. However, the fact that ecological network architecture can change through time is often overlooked in discussions on community-level processes, despite its theoretical importance. By compiling a time-series community dataset involving 50 spider species and 974 Hexapoda prey species/strains, we quantified the extent to which the architecture of predator–prey interaction networks could shift across time points. We then developed a framework for finding species that could increase the flexibility of the interaction network architecture. Those “network coordinator” species are expected to promote the persistence of species-rich ecological communities by buffering perturbations in communities. Although spiders are often considered as generalist predators, their contributions to network flexibility vary greatly among species. We also found that detritivorous prey species can be cores of interaction rewiring, dynamically interlinking below-ground and above-ground community dynamics. We further found that the predator–prey interactions between those network coordinators differed from those highlighted in the standard network-analytical framework assuming static topology. Analyses of network coordinators will add a new dimension to our understanding of species coexistence mechanisms and provide platforms for systematically prioritizing species in terms of their potential contributions in ecosystem conservation and restoration

Complete Genome Sequencing of a Community-Associated Methicillin-Resistant Staphylococcus aureus ψUSA300 Strain JICS127, a Uniquely Evolved USA300 Lineage in Japan

A ψUSA300 clone of MRSA, a derivative of USA300, is uniquely found in Japan and has 12-bp deletion on ccrB2 in type IVa staphylococcal cassette chromosome mec element. We hereby present the complete genome of ψUSA300 strain JICS127

Experimental Evaluation of Mechanical Reliability of the Impeller Blade for Large Integrally Geared Compressors

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Cerebral Glycogen Distribution and Aging

In the brain, glycogen metabolism has been implied in synaptic plasticity and learning, yet the distribution of this molecule has not been fully described. We investigated cerebral glycogen of the mouse by immunohistochemistry (IHC) using two monoclonal antibodies that have different affinities depending on the glycogen size. The use of focused microwave irradiation yielded well‐defined glycogen immunoreactive signals compared with the conventional periodic acid‐Schiff method. The IHC signals displayed a punctate distribution localized predominantly in astrocytic processes. Glycogen immunoreactivity (IR) was high in the hippocampus, striatum, cortex, and cerebellar molecular layer, whereas it was low in the white matter and most of the subcortical structures. Additionally, glycogen distribution in the hippocampal CA3‐CA1 and striatum had a ‘patchy’ appearance with glycogen‐rich and glycogen‐poor astrocytes appearing in alternation. The glycogen patches were more evident with large‐molecule glycogen in young adult mice but they were hardly observable in aged mice (1–2 years old). Our results reveal brain region‐dependent glycogen accumulation and possibly metabolic heterogeneity of astrocytes

Strongly Enhanced DD Fusion Reactions at Very Low Energies in Solids(I. Nuclear Physics)

The interplay between a nucleus and its environment is known to play an important role in nuclear reactions when the incident energy has been reduced far below the Coulomb barrier, where the cross section described by the Gamow function decreases drastically due to the steep drop in the quantum mechanical penetration of the barrier. For the fusion reactions in metals, experimental techniques were developed in which target nuclei were implanted in a metal. The DD fusion reactions were studied, so far, and an enhancement in the rate of the D(d, p)T fusion reaction over the Gamow function was found for deuterons in Ti and Yb. Here we report on further measurements of the D+D reactions in other materials. Of particular interest is the fact that the reaction rate of the D+D reactions at 2.5 keV in PdO is 50 times larger than in Ti, and the deduced screening potential amounts to 600 eV. This cannot be explained by bound-electron screening which may give a potential of 20 eV at most, but suggests the existence of an additional, and important, mechanism. Perhaps there is a fluidity of deuterons in metals that also reduces the Coulomb barrier between the interacting deuteron pair. An exhaustive study of nuclear reactions in metal would be very significant ; one would then not only simulate nuclear fusion reactions in a stellar plasma where the nuclei are immersed in a sea of electrons, but also explore the limitations of nuclear fusion at room temperature