Buckling of built-up columns of pultruded fiber-reinforced polymer C-sections

This paper presents the test results of an experimental investigation to evaluate the buckling behavior of built-up columns of pultruded profiles, subjected to axial compression. Specimens are assembled by using four (off the shelf) channel shaped profiles of E-glass fiber-reinforced polymer (FRP), having similar detailing to strut members in a large FRP structure that was executed in 2009 to start the restoration of the Santa Maria Paganica church in L’Aquila, Italy. This church had partially collapsed walls and no roof after the April 6, 2009, earthquake of 6.3 magnitude. A total of six columns are characterized with two different configurations for the bolted connections joining the channel sections into a built-up strut. Test results are discussed and a comparison is made with closed-form equation predictions for flexural buckling resistance, with buckling resistance values established from both eigenvalue and geometric nonlinear finite element analyses. Results show that there is a significant role played by the end loading condition, the composite action, and imperfections. Simple closed-form equations overestimate the flexural buckling strength, whereas the resistance provided by the nonlinear analysis provides a reasonably reliable numerical approach to establishing the actual buckling behavior

The pitfalls of inferring virus-virus interactions from co-detection prevalence data: application to influenza and SARS-CoV-2

There is growing experimental evidence that many respiratory viruses—including influenza and SARS-CoV-2—can interact, such that their epidemiological dynamics may not be independent. To assess these interactions, standard statistical tests of independence suggest that the prevalence ratio—defined as the ratio of co-infection prevalence to the product of single-infection prevalences—should equal unity for non-interacting pathogens. As a result, earlier epidemiological studies aimed to estimate the prevalence ratio from co-detection prevalence data, under the assumption that deviations from unity implied interaction. To examine the validity of this assumption, we designed a simulation study that built on a broadly applicable epidemiological model of co-circulation of two emerging or seasonal respiratory viruses. By focusing on the pair influenza–SARS-CoV-2, we first demonstrate that the prevalence ratio systematically underestimates the strength of interaction, and can even misclassify antagonistic or synergistic interactions that persist after clearance of infection. In a global sensitivity analysis, we further identify properties of viral infection—such as a high reproduction number or a short infectious period—that blur the interaction inferred from the prevalence ratio. Altogether, our results suggest that ecological or epidemiological studies based on co-detection prevalence data provide a poor guide to assess interactions among respiratory viruses

Skewed contributions of individual trees to indirect nature experiences

This is the author accepted manuscript. Final version available from Elsevier via the DOI in this record.Exposure to nature is associated with a broad range of benefits to human health. Whilst there has been exploration of how these experiences vary amongst people, the converse – how different individual organisms contribute to human nature experiences – has largely been overlooked. The most common way that people experience nature occurs indirectly, when they are in a room with a natural view. Here, we estimate variation in how individual trees provide indirect nature experiences in an urban human population. As a proxy for its contribution towards indirect nature experiences, within an extended urban area in southern England, UK (n = 612,920) we calculated the number of buildings with line of sight to each tree. We then modelled each tree’s contribution towards these experiences against potential predictors, namely tree height, land ownership, social deprivation, while controlling for human population density. We demonstrate that a small number of trees contribute disproportionately towards indirect nature experiences, with individual trees in socio-economically deprived high density housing falling within the viewscape of significantly more buildings. Further, trees in private gardens were generally more important for providing indirect nature experiences than those in public green spaces. This novel study demonstrates the skewed contribution of different organisms to human population indirect nature experiences. This approach can be applied more broadly to understand how individual organisms provide indirect, incidental and intentional nature experiences. Understanding the ecology behind human nature experiences is an important step towards linking urban design and policy for maximising the health benefits from nature.Natural Environment Research Council (NERC

Surface machining of Ti6Al4V by means of Micro-Electrical Discharging to improve adhesive joining

The Micro-Electrical Discharge Machining (Micro-EDM) technique has been employed to machine micro-patterns with shaped micro-slots on Ti6Al4V surfaces. Ti6Al4V substrates, with and without micro-slots, were bonded using a commercial epoxy adhesive. Optical microscopy and SEM were used to observe the micro-patterned Ti6Al4V surfaces before and after joining and to analyse the fracture surfaces after mechanical tests. The joints were mechanically characterised, with and without micro-patterns, by means of Single Lap Offset (SLO) shear tests under compression to understand the effect of differently shaped micro-slots. The effects of the shape of the micro-slots, their interlocking or overlapping, and their orientation, with respect to the applied load, are presented and discussed in terms of mechanical performance of the joints

Electron transport in crystalline PCBM-like fullerene derivatives: a comparative computational study

We present an extensive study of electron transport (ET) in several crystal forms of phenyl-C61-butyric acid methyl ester (PCBM) and 1-thienyl-C61-butyric acid methyl ester (ThCBM) fullerene derivatives. Our calculations are based on a localized representation of the electronic states. Orbital couplings, site energies and reorganization energies have been calculated using various density functional and semi-empirical techniques and used within the Landau–Zener, Marcus and Marcus–Levich–Jortner expressions to evaluate electron transfer rates. Electron mobilities have been then estimated by kinetic Monte Carlo (KMC) simulations. The adiabaticity of electron transfer directions within the different crystal structures has also been verified using the Landau–Zener expression. Finally, the role of low energy virtual orbitals of the fullerene molecules has been investigated using charge transport networks of increasing complexities. Our results show that these molecules may form one-, two- or three-dimensional percolation networks and that their higher energy orbitals often participate in ET. The highest mobility values were obtained for the crystal structure of ThCBM and are comparable to experimental values

Immune Responses to RHAMM in Patients with Acute Myeloid Leukemia after Chemotherapy and Allogeneic Stem Cell Transplantation

Leukemic blasts overexpress immunogenic antigens, so-called leukemia-associated antigens like the receptor for hyaluronan acid-mediated motility (RHAMM). Persistent RHAMM expression and decreasing CD8+ T-cell responses to RHAMM in the framework of allogeneic stem cell transplantation or chemotherapy alone might indicate the immune escape of leukemia cells. In the present study, we analyzed the expression of RHAMM in 48 patients suffering from acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Furthermore, we correlated transcripts with the clinical course of the disease before and after treatment. Real-time quantitative reverse transcriptase polymerase chain reaction was performed from RNA of peripheral blood mononuclear cells. T cell responses against RHAMM were assessed by tetramer staining (flow cytometry) and enzyme-linked immunospot (ELISPOT) assays. Results were correlated with the clinical outcome of patients. The results of the present study showed that almost 60% of the patients were RHAMM positive; specific T-cells recognizing RHAMM could be detected, but they were nonfunctional in terms of interferon gamma or granzyme B release as demonstrated by ELISPOT assays. Immunotherapies like peptide vaccination or adoptive transfer of RHAMM-specific T cells might improve the immune response and the outcome of AML/MDS patients