An experimental-numerical methodology for the nondestructive assessment of the dynamic elastic properties of adhesives

In the last years, lightweight design has become a priority in many industrial sectors, like as the aerospace and the automotive industry, mainly due to the strict regulations in terms of gas emission and pollution. Together with lightweight materials, the use of adhesives to join different parts permits to significantly reduce the weight of mechanical assemblies. For a proper design of the joints, the mechanical properties of adhesives should be correctly experimentally assessed. However, the experimental assessment of the adhesive mechanical properties can be complex, since they can be hardly estimated from traditional experimental tests on lap joint or butt-joint specimens. The development of an experimental procedure for the assessment of the adhesive properties is therefore of interest. In the present paper, a methodology for the assessment of the dynamic elastic properties of adhesives, i.e., Young's modulus and the loss factor, is proposed. The procedure is based on the Impulse Excitation Technique and Finite Element Analyses (FEA). An automated routine has been written to assess the elastic properties by minimizing the difference between the frequency response obtained experimentally and through FEA. The proposed methodology has been experimentally validated to estimate the mechanical properties of an epoxy adhesive for automotive applications

Dynamic behaviour of polyolefin thermoplastic hot melt adhesive under impact loading conditions

Dynamic behavior of polyolefin thermoplastic hot melt adhesive under impact loading conditions R. Ciardiello1, A. Tridello1, G. Belingardi1, L. Goglio1. 1 Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Torino, 10129, IT. The mechanical behaviour of adhesive joints under impact loadings is an active area of research due to significant industrial interests. Furthermore, the absence of a unique adopted standard for the study of bonded joints under impact loading increases the academic interests for this topic [1]. In this work, the static and the dynamic response of adhesive joints, bonded with a polyolefin hot-melt adhesive (HMA), were investigated by means of Single Lap Joint (SLJ) tests. The adhesive studied in this work is used in automotive application for bonding plastic internal and external plastic components [2], such as plastic bumpers that can be subjected to impacts during its life. The mechanical and thermal properties of this adhesive are presented in [3]. The main aim of this study is to test standard specimens, SLJ, under dynamic impacts with the use of a modified Charpy pendulum in order to compare the differences between static and dynamic behaviour. The substrate used in this activity are made of a polypropylene copolymer with 10% in weight of talc. Figure 1 shows the testing machine with the clamping system of the specimen. These special fixtures were designed by Goglio et al. [4] with the aim to apply a dynamic load on the tested SLJ. The specimen is fixed to the hammer at the front end, as shown in the right part of Figure 1; the back end is connected to a transverse tail, which hits the two stoppers fixed on the pendulum base, shown in the red circle of Figure 1. The fixtures hold the specimen during the fall of the hammer and transmit the load. A tail in aluminium alloy with T cross section was used, in order to guarantee a high stiffness during the impact, without adding excessive inertia to the system. The system is able to perform dynamic tests for SLJ specimens up to 3.75 m/s. Figure 1: Charpy pendulum used for the experimental tests. Mechanical tests show that there is a clear influence of the load rate on force-displacement diagram and on the maximum force for the tested adhesive. Figure 2 illustrates the differences between a representative curve of quasi-static test and dynamic tests with two different velocities. Figure 2: Force vs linear displacement: comparison between quasi-static and dynamic tests. Figure 3 shows the average values of the peak force and absorbed energies. This Figure illustrates that the velocity increase leads to an increase of the maximum force while the adsorbed energy significantly decreases by comparing quasi-static and dynamic tests. Figure 3: Peak loads and absorbed energy of the quasi-static and dynamic tests. Finally, the fracture surfaces of the SLJ specimens were assessed by means of visual inspection. This analysis showed that the joint separation in the quasi-static tests is mostly cohesive, whereas it becomes completely adhesive in dynamic tests. [1] J.J.M. Machado, E.A.S. Marques and L.F.M. da Silva, J. Adhes., (2017). https://doi.org/10.1080/00218464.2017.1282349. [2] G. Belingardi, V. Brunella, B. Martorana and R. Ciardiello, in Adhesives applications and properties, Cap.13, p.341, A. Rudawska Ed. (INTECH, Rijeca, 2016). [3] E. Koricho, E. Verna, G. Belingardi, B. Martorana, and V. Brunella, Int. J. Adhes. Adhes. 68, 169–181 (2016). [4] L. Goglio and M. Rossetto, in Proceedings of ESDA2006 8th Biennial ASME Conference on Engineering Systems Design and Analysis, 637-643 (2006)

Bioelectrochemical Nitrogen fixation (e-BNF): Electro-stimulation of enriched biofilm communities drives autotrophic nitrogen and carbon fixation

A new approach to microbial electrosynthesis is proposed, aimed at producing whole biomass from N2 and inorganic carbon, by electrostimulation of complex microbial communities. On a carbon-based conductor under constant polarization ( 120.7\u202fV vs SHE), an electroactive biofilm was enriched with autotrophic nitrogen fixing microorganims and led to biomass synthesis at higher amounts (up to 18 fold), as compared to controls kept at open circuit (OC). After 110\u202fdays, the electron transfer had increased by 30-fold, as compared to abiotic conditions. Metagenomics evidenced Nif genes associated with autotrophs (both Archaea and Bacteria) only in polarized biofilms, but not in OC. With this first proof of concept experiment, we propose to call this promising field \u2018bioelectrochemical nitrogen fixation\u2019 (e-BNF): a possible way to \u2018power\u2019 biological nitrogen fixation, organic carbon storage and soil fertility against desertification, and possibly a new tool to study the development of early prokaryotic life in extreme environments

A study of microbial communities on terracotta separator and on biocathode of air breathing microbial fuel cells

Recently, terracotta has attracted interest as low-cost and biocompatible material to build separators in microbial fuel cells (MFCs). However, the influence of a non-conductive material like terracotta on electroactive microbiological communities remains substantially unexplored. This study aims at describing the microbial pools developed from two different seed inocula (bovine and swine sewage) in terracotta-based air-breathing MFC. A statistical approach on microbiological data confirmed different community enrichment in the MFCs, depending mainly on the inoculum. Terracotta separators impeded the growth of electroactive communities in contact with cathodes (biocathodes), while a thick biofilm was observed on the surface (anolyte-side) of the terracotta separator. Terracotta-free MFCs, set as control experiments, showed a well-developed biocathode, Biocathode-MFCs resulted in 4 to 6-fold higher power densities. All biofilms were analyzed by high-throughput Illumina sequencing applied to 16S rRNA gene. The results showed more abundant (3- to 5-fold) electroactive genera (mainly Geobacter, Pseudomonas, Desulfuromonas and Clostridia MBA03) in terracotta-free biocathodes. Nevertheless, terracotta separators induced only slight changes in anodic microbial communities

Anti-inflammatory response of IL-4, IL-10 and TGF-beta in patients with systemic inflammatory response syndrome.

The systemic inflammatory response syndrome (SIRS) is an inflammatory process seen in association with a large number of clinical infective and non-infective conditions. The aim of this study was to investigate the role of anti-inflammatory cytokines such as interleukin-4 (IL-4), interleukin-10 (IL-10), and transforming growth factor-beta (TGF-beta). Serum levels of IL-4, IL-10 and TGF-beta were determined in 45 patients with SIRS: 38 patients had SIRS of infectious origin, whereas seven patients had non-infectious SIRS. Twenty healthy subjects were used as controls. Serum levels of IL-4, IL-10 and TGF-beta were determined by an immunoenzyme assay. A significant increase of IL-4 was observed in these patients at the time of diagnosis and 5 days later. In contrast, serum levels of IL-10 were not increased at the time of diagnosis, but a slight decrease was noted after 5 days. Serum levels of TGF-beta were not increased at time of diagnosis, and a slight increase was observed after 5 days. Serum levels of IL-4 were significantly higher in patients with infectious SIRS at the time of diagnosis, whereas no significant difference between infectious and non-infectious SIRS was noted for serum levels of IL-10 and TGF-beta at the time of diagnosis and 5 days later. During SIRS, serum levels of IL-4 were significantly increased with a significant correlation between IL-4 and mortality, and only levels of IL-4 were significantly increased in the SIRS caused by infectious stimuli

Satellite university campuses and economic development in peripheral regions

Satellite university campuses – whereby established universities decentralise part of their activities, often to areas previously lacking a university – contribute to the diversification of university systems. While satellite campuses, due to their small scale and limited resources, might perform some activities less efficiently than their larger parent universities, we argue that they are uniquely placed to serve the needs of their localities. Based on the case of a satellite campus in North-West Italy, we show that: (i) the campus’ main contribution lies in widening access to higher education to residents who would not attend university in the absence of local provision; (ii) the campus contributes to local development also through research and business and community engagement, and by stimulating local demand for knowledge-intensive services; (iii) research and engagement are more effective for local development where local firms possess relevant absorptive capacity and where there is a favourable institutional framework

A comparison of methods to quantify greenhouse gas emissions of cropping systems in LCA

Carbon dioxide and nitrous oxide are two important greenhouse gases (GHG) released from cropping systems. Their emissions can vary substantially with climate, soil, and crop management. While different methods are available to account for GHG emissions in life cycle assessments (LCA) of crop production, there are no standard procedures. In this study, the objectives were: (i) to compare several methods of estimating CO2 and N2O emissions for a LCA of cropping systems and (ii) to estimate the relative contribution of soil GHG emissions to the overall global warming potential (GWP) using results from a field experiment located in Manitoba, Canada. The methods were: (A) measurements; (B) Tier I and (C) Tier II IPCC (Intergovernmental panel on Climate Change) methodology, (D) a simple carbon model combined with Intergovernmental Panel for Climate Change (IPCC) Tier II methodology for soil N2O emissions, and (E) the DNDC (DeNitrification DeComposition) agroecosystem model. The estimated GWPs (−7.2–17 Mg CO2eq ha−1 y−1; −80 to 600 kg CO2eq GJ−1 y−1) were similar to previous results in North America and no statistical difference was found between GWP based on methods D and E and GWP based on observations. The five methods gave estimates of soil CO2 emissions that were not statistically different from each other, whereas for N2O emissions only DNDC estimates were similar to observations. Across crop types, all methods gave comparable CO2 and N2O emission estimates for perennial and legume crops, but only DNDC gave similar results with respect to observations for both annual and cereal crops. Whilst the results should be confirmed for other locations, the agroecosystem model and method D can be used, at certainly one selected site, in place of observations for estimating GHGs in agricultural LCA

Assessing the potential of soil carbonation and enhanced weathering through Life Cycle Assessment : A case study for Sao Paulo State, Brazil

We acknowledge funding through the UP-Green-LCA (NE/P019668/1) and SOILS-R-GGREAT (NE/P019498/1) projects of the greenhouse gas removal (GGR) programme. The GGR programme is financed by the UK Natural Environment Research Council (NERC), Engineering and Physical Sciences Research Council, Economic and Social Science Research Council (ESRC) and the UK department for Business, Energy and Industrial Strategy (BEIS). The authors wish to acknowledge the Royal Society for providing precious insights at the Sackler Forum in 2017. No new data were collected in the course of this research. This study was an analysis of existing data that are publicly available from the cited literature.Peer reviewedPublisher PD