Carbon nanotube yarns are micron-scale fibers comprised by tens of thousands of carbon nanotubes in their cross section and exhibiting piezoresistive characteristics that can be tapped to sense strain. This paper presents the details of novel foil strain gauge sensor configurations comprising carbon nanotube yarn as the piezoresistive sensing element. The foil strain gauge sensors are designed using the results of parametric studies that maximize the sensitivity of the sensors to mechanical loading. The fabrication details of the strain gauge sensors that exhibit the highest sensitivity, based on the modeling results, are described including the materials and procedures used in the first prototypes. Details of the calibration of the foil strain gauge sensors are also provided and discussed in the context of their electromechanical characterization when bonded to metallic specimens. This characterization included studying their response under monotonic and cyclic mechanical loading. It was shown that these foil strain gauge sensors comprising carbon nanotube yarn are sensitive enough to capture strain and can replicate the loading and unloading cycles. It was also observed that the loading rate affects their piezoresistive response and that the gauge factors were all above one order of magnitude higher than those of typical metallic foil strain gauges. Based on these calibration results on the initial sensor configurations, new foil strain gauge configurations will be designed and fabricated, to increase the strain gauge factors even more.

Tailoring the properties of magnetic vortices through the preparation of structured multilayers is discussed. The dependence of the vortex core radius r on the effective anisotropy is derived within a simple model, which agrees with our simulations. As the perpendicular anisotropy increases, r also increases until a perpendicular magnetization appears in the disk rim. Co/Pt multilayer disks were studied; x-ray microscopy confirms qualitatively the predicted behavior. This is a favorable system for implementing vortex-based spin-transfer nano-oscillator devices, with enhanced rf power resulting both from the increase in the core size and synchronization afforded by the coupling of the Co layers.

Nowadays, the attainment of microsystems that integrate most of the stages involved in an analytical process has raised an enormous interest in several research fields. This approach provides experimental set-ups of increased robustness and reliability, which simplify their application to in-line and continuous biomedical and environmental monitoring. In this work, a novel, compact and autonomous microanalyzer aimed at multiwavelength colorimetric determinations is presented. It integrates the microfluidics (a three-dimensional mixer and a 25 mm length “Z-shape” optical flow-cell), a highly versatile multiwavelength optical detection system and the associated electronics for signal processing and drive, all in the same device. The flexibility provided by its design allows the microanalyzer to be operated either in single fixed mode to provide a dedicated photometer or in multiple wavelength mode to obtain discrete pseudospectra. To increase its reliability, automate its operation and allow it to work under unattended conditions, a multicommutation sub-system was developed and integrated with the experimental set-up. The device was initially evaluated in the absence of chemical reactions using four acidochromic dyes and later applied to determine some key environmental parameters such as phenol index, chromium(VI) and nitrite ions. Results were comparable with those obtained with commercial instrumentation and allowed to demonstrate the versatility of the proposed microanalyzer as an autonomous and portable device able to be applied to other analytical methodologies based on colorimetric determinations.

Background: Depression is a common and recurrent condition among older adults and is associated with poor quality of life and increased health care utilization and costs. The purpose of this pilot study was to assess the feasibility of delivering a psychosocial intervention targeting depression, and to develop the procedures to conduct a cluster randomized controlled trial among older adults registered with primary care clinics in poor neighbourhoods of São Paulo, Brazil. Methods: We conducted a pilot study of a two-arm cluster, non-randomized controlled trial. Two primary care clinics adhering to the Family Health Strategy were allocated to either the intervention or the control arm. In the control arm, patients received enhanced usual care consisting of staff training for improved recognition and management of depression. In the intervention arm, alongside the enhanced usual care, patients received a 17-week psychosocial intervention delivered by health workers assisted with an application installed in a tablet. Results: We randomly selected 579 of 2020 older adults registered in the intervention clinic to participate in the study. Among these individuals, 353 were assessed for depression and 40 (11.0%) scored at least 10 on the PHQ-9 and were therefore invited to participate. The consent rate was 33/40 (82%) with a resulting yield of 33/579 (5.7%). In the control arm, we randomly selected 320 older adults among 1482 registered in the clinic, 223 were assessed for depression and 28 (12.6%) scored 10 or above on the PHQ-9. The consent rate was 25/28 (89%), with a resulting yield of 25/320 (7.8%). Of the 33 who consented in the intervention arm, 19 (59.4%) completed all sessions. The mean PHQ-9 at follow-up (approximately 30 weeks after inclusion) were 12.3 (SD = 3.7) and 3.8 (SD = 3.9) in the control and intervention arms, respectively. Follow-up rates were 92 and 94% in control and intervention arms, respectively. Conclusions: Identification and engagement of clinics, randomization, recruitment of individuals, measures, and baseline and follow-up assessments all proved to be feasible in primary care clinics in São Paulo, Brazil. Results support the development of a definitive cluster randomized controlled trial. Trial registration: This study was retrospectively registered with Registro Brasileiro de Ensaios Clínicos (ReBEC), number RBR-5nf6wd. Registered 06 August 2018.