Toughness improvement of polyamide 11 assessed via quasistatic tensile tests on notched round bars

International audienceToughening a polymeric material by adding rubber particles is a common technique used forglassy polymers and measured by means of Charpy or Izod impact tests. These latter aredetermined under dynamic conditions, thus at high strain rate or equivalently at very lowtemperature for polymeric materials.This work is devoted to three grades of semi-crystalline PolyAmide 11 (PA11), used in alarge number of engineering components. Service conditions are close to the glass transitiontemperature. Therefore, tests with quasi-static loading are expected to be more appropriate.The aim of the study is to find a methodology allowing the quantification of toughnessimprovement. To this end, an experimental database was constituted. Three grades of PA11were involved, that enable to analyze effects of: i) aging, ii) addition of a plasticizer iii)addition of rubber particles. Tensile tests were then carried out on notched round bars.Trends of load versus notch opening displacement curves are investigated. Longitudinalcross-sections on specimens issued from interrupted tests and fracture surfaces wereexamined in order to study deformation and damage mechanisms. An attempt is made to linktoughness improvement to the increase in global fracture energy

Microfluidics-based approaches to the isolation of African trypanosomes

African trypanosomes are responsible for significant levels of disease in both humans and animals. The protozoan parasites are free-living flagellates, usually transmitted by arthropod vectors, including the tsetse fly. In the mammalian host they live in the bloodstream and, in the case of human-infectious species, later invade the central nervous system. Diagnosis of the disease requires the positive identification of parasites in the bloodstream. This can be particularly challenging where parasite numbers are low, as is often the case in peripheral blood. Enriching parasites from body fluids is an important part of the diagnostic pathway. As more is learned about the physicochemical properties of trypanosomes, this information can be exploited through use of different microfluidic-based approaches to isolate the parasites from blood or other fluids. Here, we discuss recent advances in the use of microfluidics to separate trypanosomes from blood and to isolate single trypanosomes for analyses including drug screening

Provisional Survey of Aitutaki, Cook islands Sites and Monuments May-June 2017

The archaeological survey work detailed in this report was undertaken by Colin Richards and Jane Downes (University of the Highlands and Islands, UK), Kate Welham (Bournemouth University, UK), Francisco Torres Hochstetter (MAPSE, Rapa Nui (Easter Island), Chile) and Lawrence Shaw (New Forest National Park Authority, UK), working with Ngaakitai Pureariki (Punarei Aitutaki), with the permission of the Aitutaki Council, and Cook Islands Research Permit (Ref. 15-16a), working between 23rd May and 2nd June 2017. The archaeological work comprised site survey and location using GPS, geophysical survey, and surface collection of artefacts. A database of the sites has been produced as a Cultural Heritage Record, and lodged with the Aitutaki Islands Council. All artefacts have been left on the island with the Aitutaki Islands Council

Care for the Future: Heritage Education in the Context of Rapa Nui (Easter Island) and Other Small Island Communities.

Education is accepted to be the principal means by which archaeological heritage can be both enjoyed and preserved. Links between research and education through outreach are an important part of archaeological projects on Rapa Nui, for example providing new information for site interpretation. Knowledge exchange between researchers and heritage managers can be another important outcome, or impact, of research. The preliminary findings from doctoral interview-based research with residents pertaining to archaeology, heritage management and heritage education programs that have taken place on Rapa Nui the island will be discussed here. We examine the role archaeological heritage is playing in Rapa Nui in education contexts, and make some observations as to the impact and legacy of this important work. One aspect of the education program is in developing links between researchers, heritage managers, museums and school pupils between Rapa Nui, and the islands of Orkney, Scotland. The benefits and potential of links between small island communities in heritage education and management are considered in this paper

Failure of polyamide 11 using a damage finite elements model

International audienceThe present paper focuses ..