Fixation of transparent bone pins with photocuring biocomposites

Bone fractures are in need of rapid fixation methods, but the current strategies are limited to metal pins and screws, which necessitate secondary surgeries upon removal. New techniques are sought to avoid surgical revisions, while maintaining or improving the fixation speed. Herein, a method of bone fixation is proposed with transparent biopolymers anchored in place via light-activated biocomposites based on expanding CaproGlu bioadhesives. The transparent biopolymers serve as a UV light guide for the activation of CaproGlu biocomposites, which results in evolution of molecular nitrogen (from diazirine photolysis), simultaneously expanding the covalently cross-linked matrix. Osseointegration additives of hydroxyapatite or Bioglass 45S5 yield a biocomposite matrix with increased stiffness and pullout strength. The structure-property relationships of UV joules dose, pin diameter, and biocomposite additives are assessed with respect to the apparent viscosity, shear modulus, spatiotemporal pin curing, and lap-shear adhesion. Finally, a model system is proposed based onex vivoinvestigation with bone tissue for the exploration and optimization of UV-active transparent biopolymer fixation

Quantification of carbon and phosphorus co-limitation in bacterioplankton: new insights on an old topic

Because the nature of the main resource that limits bacterioplankton (e.g. organic carbon [C] or phosphorus [P]) has biogeochemical implications concerning organic C accumulation in freshwater ecosystems, empirical knowledge is needed concerning how bacteria respond to these two resources, available alone or together. We performed field experiments of resource manipulation (2×2 factorial design, with the addition of C, P, or both combined) in two Mediterranean freshwater ecosystems with contrasting trophic states (oligotrophy vs. eutrophy) and trophic natures (autotrophy vs. heterotrophy, measured as gross primary production:respiration ratio). Overall, the two resources synergistically co-limited bacterioplankton, i.e. the magnitude of the response of bacterial production and abundance to the two resources combined was higher than the additive response in both ecosystems. However, bacteria also responded positively to single P and C additions in the eutrophic ecosystem, but not to single C in the oligotrophic one, consistent with the value of the ratio between bacterial C demand and algal C supply. Accordingly, the trophic nature rather than the trophic state of the ecosystems proves to be a key feature determining the expected types of resource co-limitation of bacteria, as summarized in a proposed theoretical framework. The actual types of co-limitation shifted over time and partially deviated (a lesser degree of synergism) from the theoretical expectations, particularly in the eutrophic ecosystem. These deviations may be explained by extrinsic ecological forces to physiological limitations of bacteria, such as predation, whose role in our experiments is supported by the relationship between the dynamics of bacteria and bacterivores tested by SEMs (structural equation models). Our study, in line with the increasingly recognized role of freshwater ecosystems in the global C cycle, suggests that further attention should be focussed on the biotic interactions that modulate resource co-limitation of bacteria.This research was supported by Junta de Andalucía (Excelencia P09-RNM-5376 to JMMS) and the Spanish Ministry Ciencia e Innovación (CGL2011-23681 to PC)

Bacteria and their distribution under red-tide conditions

Survey of the density of red-tide organisms and bacterioplankton as well as simultaneous determinations of temperature, salinity, pH, secchi disc and dissolved oxygen were carried out at four stations in the Kaštela Bay (middle Adriatic Sea) on a weekly basis between June 15 and September 20, 1989. A close connection between bacterioplankton and Gonyaulax polyedra was observed during the bloom manifested by high coefficients of correlation between them in the surface layers. No correlation was established in the bottom layers since vertical gradients of bacterioplankton density were considerably weaker than in phytoplankton. These differences were also shown in strong vertical gradient of pH and 02-saturation

RFID-based Efficient Method for Parking Slot Car Detection

Enabling a sustainable urban mobility is one of primary goals of the so-called Smart Cities vision, and the deployment of smart parking systems represents a key aspect. The proper operation of these systems heavily depends on their ability to automatically detect the presence of vehicles in the parking spaces. To date, this problem is solved by expensive wireless/wired systems. As the car presence is only one bit of information, with importance of knowing the ID of a slot, in this paper we consider the possibility of using Battery Assisted Passive (BAP) tags for those purposes. Specifically, the considered system uses a BAP tag, with the battery replaced by a solar cell. Once the light level is below some thresholds (ensured by car on top of it), the tag stops transmitting the data, and the system recognizes the slot as occupied. The feasibility of the proposed solution is experimentally verified, and first results are reported