Biocompatibility of a lab-on-a-pill sensor in artificial gastrointestinal environments

n this paper, we present a radiotelemetry sensor, designed as a lab-in-a-pill, which incorporates a two-channel microfabricated sensor platform for real-time measurements of temperature and pH. These two parameters have potential application for use in remote biological sensing (for example they may be used as markers that reflect the physiological environment or as indicators for disease, within the gastrointestinal tract). We have investigated the effects of biofouling on these sensors, by exploring their response time and sensitivity in a model in vitro gastrointestinal system. The artificial gastric and intestinal solutions used represent a model both for fasting, as well as for the ingestion of food and subsequent digestion to gastrointestinal chyme. The results showed a decrease in pH sensitivity after exposure of the sensors for 3 h. The response time also increased from an initial measurement time of 10 s in pure GI juice, to ca. 25 s following the ingestion of food and 80 s in simulated chyme. These in vitro results indicate that changes in viscosity in our model gastrointestinal system had a pronounced effect on the unmodified sensor

A programmable microsystem using system-on-chip for real-time biotelemetry

A telemetry microsystem, including multiple sensors, integrated instrumentation and a wireless interface has been implemented. We have employed a methodology akin to that for System-on-Chip microelectronics to design an integrated circuit instrument containing several "intellectual property" blocks that will enable convenient reuse of modules in future projects. The present system was optimized for low-power and included mixed-signal sensor circuits, a programmable digital system, a feedback clock control loop and RF circuits integrated on a 5 mm × 5 mm silicon chip using a 0.6 μm, 3.3 V CMOS process. Undesirable signal coupling between circuit components has been investigated and current injection into sensitive instrumentation nodes was minimized by careful floor-planning. The chip, the sensors, a magnetic induction-based transmitter and two silver oxide cells were packaged into a 36 mm × 12 mm capsule format. A base station was built in order to retrieve the data from the microsystem in real-time. The base station was designed to be adaptive and timing tolerant since the microsystem design was simplified to reduce power consumption and size. The telemetry system was found to have a packet error rate of 10<sup>-</sup><sup>3</sup> using an asynchronous simplex link. Trials in animal carcasses were carried out to show that the transmitter was as effective as a conventional RF device whilst consuming less power

Multiple plasmon resonances from gold nanostructures

Understanding and controlling plasmon resonances from metallic nanoscale structures have been the focus of much attention recently, with applications including local surface plasmon resonance sensing, surface enhanced Raman spectroscopy, and negative refractive index materials. In this letter the authors demonstrate the fabrication of uniform arrays of split rings from gold and show that such structures are capable of supporting multiple plasmon resonances. The authors show that up to five plasmon resonances can be identified and use finite difference time domain modeling and absorption spectroscopy to fully characterize and identify each resonance. The implications of higher order surface plasmon resonances for sensing are discussed

Reversible addition-fragmentation chain transfer aqueous dispersion polymerization of 4-hydroxybutyl acrylate produces highly thermoresponsive diblock copolymer nano-objects

The reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA) using a poly(glycerol monomethacrylate) (PGMA) precursor is an important prototypical example of polymerization-induced self-assembly. 4-Hydroxybutyl acrylate (HBA) is a structural isomer of HPMA, but the former monomer exhibits appreciably higher aqueous solubility. For the two corresponding homopolymers, PHBA is more weakly hydrophobic than PHPMA. Moreover, PHBA has a significantly lower glass transition temperature (Tg) so it exhibits much higher chain mobility than PHPMA at around ambient temperature. In view of these striking differences, we have examined the RAFT aqueous dispersion polymerization of HBA using a PGMA precursor with the aim of producing a series of PGMA57–300-PHBA100–1580 diblock copolymer nano-objects by systematic variation of the mean degree of polymerization of each block. A pseudo-phase diagram is constructed using transmission electron microscopy to assign the copolymer morphology after employing glutaraldehyde to cross-link the PHBA chains and hence prevent film formation during grid preparation. The thermoresponsive character of the as-synthesized linear nano-objects is explored using dynamic light scattering and temperature-dependent rheological measurements. Comparison with the analogous PGMAx-PHPMAy formulation is made where appropriate. In particular, we demonstrate that replacing the structure-directing PHPMA block with PHBA leads to significantly greater thermoresponsive behavior over a much wider range of diblock copolymer compositions. Given that PGMA-PHPMA worm gels can induce stasis in human stem cells (see Canton et al., ACS Central Science, 2016, 2, 65–74), our findings are likely to have implications for the design of next-generation PGMA-PHBA worm gels for cell biology applications

Supernova Interaction with a Circumstellar Medium

The explosion of a core collapse supernova drives a powerful shock front into the wind from the progenitor star. A layer of shocked circumstellar gas and ejecta develops that is subject to hydrodynamic instabilities. The hot gas can be observed directly by its X-ray emission, some of which is absorbed and re-radiated at lower frequencies by the ejecta and the circumstellar gas. Synchrotron radiation from relativistic electrons accelerated at the shock fronts provides information on the mass loss density if free-free absorption dominates at early times or the size of the emitting region if synchrotron self-absorption dominates. Analysis of the interaction leads to information on the density and structure of the ejecta and the circumstellar medium, and the abundances in these media. The emphasis here is on the physical processes related to the interaction.Comment: 22 pages, 7 figures, to appear as a Chapter in "Supernovae and Gamma-Ray Bursts," edited by K. W. Weiler (Springer-Verlag

Temporal, spatial, and structural patterns of adult trembling aspen and white spruce mortality in Quebec's boreal forest

Temporal, spatial, and structural patterns of adult trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss) mortality were studied in intact 150-year-old stands in the southwestern boreal forest of Quebec. For both species, mortality decreases (number of dead trees/total number of trees) with distance from the lake edge until 100-150 m, from which point it slightly increases. Strong peaks in mortality were found for 40- to 60-year-old aspen mainly between 1974 and 1992. Such mortality in relatively young aspen is likely related to competition for light from the dominant canopy trees. Also, the recruitment of this young aspen cohort is presumably the result of a stand breakup that occurred when the initial aspen-dominated stand was between 90 and 110 years old. For spruce, strong peaks in mortality were found in 110- to 150-year-old trees and they occurred mainly after 1980. No clear explanation could be found for these peaks, but we suggest that they may be related to senescence or weakening of the trees following the last spruce budworm outbreak. Suppressed and codominant aspen had a much higher mortality ratio than spruce in the same height class, while more surprisingly, no difference in mortality rate was found between dominant trees of the two species. Most spruce trees were found as standing dead, which leads us to reject the hypothesis that windthrow is an important cause of mortality for spruce in our forests

Hybotinae (Diptera, Hybotidae) of the National Park of Jaú, Amazonas, Brazil, with description of five new species of Syneches Walker

The composition of Hybotinae of the National Park of Jaú was studied. Sixteen species of Hybotinae are recorded and five new species of Syneches Walker are described and illustrated: Syneches hispidus sp. nov., S. jauensis sp. nov., S. longiflagellatus sp. nov., S. rafaeli sp. nov. and S. vidali sp. nov.A composição de Hybotinae do Parque Nacional do Jaú foi estudada. Dezesseis espécies de Hybotinae são registradas e cinco espécies novas de Syneches Walker são descritas e ilustradasSyneches hispidus sp. nov., S. jauensis sp. nov., S. longiflagellatus sp. nov., S. rafaeli sp. nov. e S. vidali sp. nov