Crystal orientation effects in scratch testing with a spherical indenter

Spherical scratch tests were conducted in individual grains of a randomly oriented polycrystalline body-centered-cubic (bcc) Ti-Nb alloy. For each grain, scratch tests were conducted at four different levels of normal load, which resulted in varying amounts of plastic strain during indentation. The results show a dependence of the horizontal load component on the crystallographic orientation and on the amount of plastic strain. The component of the horizontal force that resulted from plastic deformation was found to correlate with the active slip systems for the particular grain orientation. © 2010 Materials Research Society.

Producing facial composite sketches in remote cognitive interviews:a preliminary investigation

Justice systems around the world are increasingly turning to videoconferencing as a means to reduce delays and reduce costs in legal processes. This preliminary research examined whether interviewing a witness remotely - without physical co-presence of the witness and interviewer - could facilitate the production of quality facial composite sketches of suspects. In Study 1, 42 adults briefly viewed a photograph of a face. The next day they participated in Cognitive Interviews with a forensic artist, conducted either face-to-face or remotely via videoconference. In Study 2, 20 adults participated in videoconferenced interviews, and we manipulated the method by which they viewed the developing sketch. In both studies, independent groups of volunteers rated the likeness of the composites to the original photographs. The data suggest that remote interviews elicited effective composites; however, in Study 1 these composites were considered poorer matches to the photographs than were those produced in face-to-face interviews. The differences were small, but significant. Participants perceived several disadvantages to remote interviewing, but also several advantages including less pressure and better concentration. The results of Study 2 suggested that different sketch presentation methods offered different benefits. We propose that remote interviewing could be a useful tool for investigators in certain circumstances. © 2013 Taylor & Francis.

Human mesenchymal stem cells stimulate EaHy926 endothelial cell migration:combined proteomic and in vitro analysis of the influence of donor-donor variability

Mesenchymal stem cells (MSCs) stimulate angiogenesis within a wound environment and this effect is mediated through paracrine interactions with the endothelial cells present. Here we report that human MSC-conditioned medium (n=3 donors) significantly increased EaHy-926 endothelial cell adhesion and cell migration, but that this stimulatory effect was markedly donor-dependent. MALDI-TOF/TOF mass spectrometry demonstrated that whilst collagen type I and fibronectin were secreted by all of the MSC cultures, the small leucine rich proteoglycan, decorin was secreted only by the MSC culture that was least effective upon EaHy-926 cells. These individual extracellular matrix components were then tested as culture substrata. EaHy-926 cell adherence was greatest on fibronectin-coated surfaces with least adherence on decorin-coated surfaces. Scratch wound assays were used to examine cell migration. EaHy-926 cell scratch wound closure was quickest on substrates of fibronectin and slowest on decorin. However, EaHy-926 cell migration was stimulated by the addition of MSC-conditioned medium irrespective of the types of culture substrates. These data suggest that whilst the MSC secretome may generally be considered angiogenic, the composition of the secretome is variable and this variation probably contributes to donor-donor differences in activity. Hence, screening and optimizing MSC secretomes will improve the clinical effectiveness of pro-angiogenic MSC-based therapies.

Thermal effects on the photoelastic coefficient of polymer optical fibers

We measure the radial profile of the photoelastic coefficient C(r) in single-mode polymer optical fibers (POFs), and we determine the evolution of C(r) after annealing the fibers at temperatures from 40°C to 80°C. We demonstrate that C(r) in the fibers drawn from a preform without specific thermal pre-treatment changes and converges to values between 1.2 and 1.6×10-12 Pa-1 following annealing at 80°C. The annealed fibers display a smoothened radial profile of C(r) and a lowered residual birefringence. In contrast, the mean value of C(r) of the fiber drawn from a preform that has been pre-annealed remains constant after our annealing process and is significantly higher, i.e., 4×10-12 Pa-1. The annealing process decreases the residual birefringence to a lower extent as well. These measurements indicate the impact of annealing on the thermal stability of the photoelastic coefficient of POFs, which is an essential characteristic in view of developing POF-based thermomechanical sensors.