Presegmentation procedure generates smooth-sided microfluidic devices: unlocking multiangle imaging for everyone?

We present a simple procedure to create smooth-sided, transparent polymer-based microfluidic devices by presegmentation with hydrophobized glass slides. We study the hypothesis that the smooth side planes permit rapid multiangle imaging of microfluidic systems in contrast to the turbid side planes that result from cutting the polymer. We compare the compatibility of the entire approach with the conventional widefield microscopy, confocal and 2-photon microscopy, as well as three-dimensional (3D) rendering and discuss limitations and potential applications

The Significance of Creativity for Teaching Philosophy

Although creativity constitutes a central human ability that needs to be fostered in school, research in didactics of philosophy hasn’t so far developed accounts of how to train creativity systematically. In this paper I will provide the foundations for a didactics of creativity for philosophy and ethics education. The approach is based on the insight that creativity is an important competence to be promoted in philosophy and ethics classrooms. I will define the concept of creativity and review key empirical findings from the field of educational psychology and psychology of learning which will help me working out a framework for fostering creativity in the philosophy classroom. Central to this is the idea that creativity can only be taught if the use of creative task types is preceded by a phase of acquiring domain-specific philosophical and ethical competences and knowledge. I will then argue that this objective can be implemented particularly well through the design thinking method. In this context, task types that promote divergent thinking are particularly effective. I will use three classroom examples to illustrate how creativity could be fostered in philosophy and ethics classes

Titration of Intertrial Interval in the Matching-to-Sample Paradigm

Investigators have used many different values for the ITI in investigating the variables in matching-to-sample. Holt and Shafer (1973), showed that the ITI itself influences matching performance. In the present experiment the titration method was employed to determine the optimal or preferred ITI for pigeons. Three Ss began each session with an ITI of 0 sec. Three other Ss began each session with an ITI of 60 sec. During the session two consecutive correct responses reduced the ITI by 2 secs while a single error would increase the ITI by 2 secs. The results showed that the 60 sec ITI group worked down to the 0 sec ITI. However, performance at the 0 sec ITI then decreased. The 0 sec ITI group maintained the 0 sec ITI and performance improved in the second half of a session. The results were interpretated as suggesting that the titration method maintains observing behavior which accounts for high accuracy in matching-to-sample. Amsel\u27s frustration hypothesis is also considered to account for the distribution of errors within a session

Fracture mechanics of PVDF polymeric material : specimen geometry effects

International audiencePolyvinylidene fluoride (PVDF) is a semi-crystalline polymer that has been widely studied for structural applications, because it exhibits good mechanical properties and chemical resistance. During viscoplastic deformation, the material whitens after the onset of necking due to nucleation and growth of voids. Mechanical tests on cracked specimens show the crack instability on DENT specimens whereas stable crack growth on SENB specimens is also encountered. In the global approach of non linear fracture mechanics framework, the two-parameter approach indicates that according to the opening stress state in the remaining ligament, the crack growth can be more or less stable. Namely, tensile crack specimens such as DENT favour instabilities whereas bending specimens (like SENB) are proved to present stable cracking. This work deals with computing Q-stresses on DENT and SENB specimens with the help of FE modelling. The material toughness JIC is then determined by means of experimental data gathered with both specimens. JIC depends on the specimen geometry. A JIC-Q curve is then plotted for the PVDF material at 20°C

Microfluidic devices for drug assays

In this review, we give an overview of the current state of microfluidic-based high-throughput drug assays. In this highly interdisciplinary research field, various approaches have been applied to high-throughput drug screening, including microtiter plate, droplets microfluidics as well as continuous flow, diffusion and concentration gradients-based microfluidic drug assays. Therefore, we reviewed over 100 recent publications in the field and sorted them according to their microfluidic approach. As a result, we are showcasing, comparing and discussing broadly applied approaches as well as singular promising ones that might contribute to shaping the future of this field

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