Nanocomposite powders of hydroxyapatite-graphene oxide for biological applications

The repair of bone fractures is a clinical challenge for patients with impaired healing, such as osteoporosis. Currently, different strategies have been developed to design new biomaterials, enhancing their interactions with biological systems and conducting the cellular behavior in the desired direction to help fracture healing. In the present work, hydroxyapatite-graphene oxide (HA-GO) nanocomposites were produced and the morphological and physicochemical influences of the addition of 0.5 wt%, 1.0 wt% and 1.5 wt% of GO to HA were observed. FEG-SEM and TEM analyses of HA-GO nanocomposites showed HA nanoparticles adhered to the surface of the GO sheets, suggesting an effective method to form nanostructured graphene-based biomaterials. As confirmation, physicochemical analyses by Raman, FTIR and TGA demonstrated a strong affinity between HA and GO, according to the increase of concentration from 0.5 wt% to 1.5 wt% GO in the HA-GO nanocomposites. Also, in order to evaluate the HA-GO nanocomposites behavior under biological microenvironment, in vitro bioactivity and indirect cytotoxicity tests were performed. FEG-SEM analyses confirmed the positive results for the bioactivity properties of HA-GO nanocomposite and indirect cytotoxicity demonstrated that even with a decrease in the hDPSCs viability and proliferation, when increasing to 1.5 wt% of GO concentration, high level of cell viability was exhibited by HA-GO nanocomposites. These biological results suggested the 0.5 wt% HA-GO nanocomposite as a potential bioactive bone graft and a promising biomaterial for bone tissue regeneration, when compared to the pure HA.     

Study of the influence of adding styrene–ethylene/butadiene–styrene in acrylonitrile–butadiene–styrene and polyethylene blends

This work studies the recovery of two grades of acrylonitrile–butadiene–styrene (ABS) contaminated with low‐density polyethylene (LDPE), by adding styrene–ethylene/butadiene–styrene (SEBS). To simulate contaminated ABS, virgin ABS was mixed with 1, 2, 4, and 8% of LDPE and then extruded at 220°C. After this, the ABS with the highest percentage of LDPE (8%) was mixed with 1, 2, 4, and 8% of SEBS and then extruded. Different blends were mechanically, rheologically, optically, and dimensionally characterized to study how different percentages of LDPE and SEBS modify their properties. The results obtained show how the tensile strength, Young modulus, elongation, and impact strength linearly decrease as the LDPE amount increases, for both natural and black ABS. Through the addition of SEBS to contaminated ABS, it is possible to improve its impact strength and elongation values nearly to those of virgin ABS. However, its tensile strength and Young modulus show no improvement, and even show a slight reduction. Regarding the rheological properties, the LDPE contamination in ABS causes a remarkable decrease in viscosity, and adding SEBS to the blend lowers its viscosity even further for both natural and black grades. This reduction is not a negative aspect, but rather quite the reverse, as the more fluid the material, the easier the mold injection process becomes. POLYM. ENG. SCI., 54:1313–1324, 2014. © 2013 Society of Plastics Engineers     

Denitrification en continu a l'aide de microorganismes immobilises sur des supports solides

In this paper, we describe a study of biological denitrification by immobilized cells. Nitrates are reduced in sterile solutions by Pseudomonas aeruginosa immobilized in a fixed bed reactor, and in synthetic waste water by mixed cultures immobilized into a fluidized bed reactor.The fixed bed reactor is a Plexiglas column filled with corn stovers (Table 1). It is 0.05 m in diameter and 0.55 in height, its volume being approx. 11. The fresh medium is injected at the base of the column and the liquid level is regulated by an overflow weir. Reactor and carrier are sterilized with ethylene-oxide. After sterilization 1 l. of a growing batch culture of Pseudomonas aeruginosa is introduced aseptically and the reactor is then fed continuously (45 ml h⁻¹) with fresh medium (N---NO₃ = 40 mg l⁻¹) until the first steady state is reached.Nitrates and nitrites are determinated by means of a colorimetric method.Reactor efficiency remains constant for over 40 days. Nitrates and nitrites concentrations are measured inside the reactor for flow varying from 2 to 16 ml min⁻¹ (Fig. 2). Reductions of nitrates and nitrites seem to be two first-order reactions (Fig. 3 and Table 2) and constant rate increases with flow rate (Fig. 4). Until nitrate concentration reaches 960 mg/l⁻¹ (N---NO₃) degradation is correct (Figs 5 and 6), beyond nitrites, which have been formed, seem to be inhibitor.Using this reactor, 50 mg N---NO₃ have been reduced per hour and per liter of empty reactor, but it may be possible to reduce 140 mg N---NO₃ l⁻¹ h⁻¹ if fresh medium contains 200 mg N---NO₃ l⁻¹.The fluidized bed reactor is a Plexiglas column filled with earthenware. It is 0.05 m in diameter and 3.15 m in height, its volume being approx. 6.201. Fresh medium is injected at the base of the column and the liquid level is regulated by an overflow weir. Figure 7 shows the retention time of the liquid in the reactor in relation to flow. The first steady state has been reached after 2 weeks, and it has not been possible to know half life time of the column.Four experiments were conducted (Table 3) and, for each nitrate, nitrite and methanol concentrations in the reactor were measured (Fig. 8). So, it appears that reduction of nitrates and nitrites are two first-order reactions (Table 4) and that constant rate values, which are higher than in fixed bed reactor, increase with flow.The reactor is more affected by a flow shift than by a nitrate concentration shift in fresh medium, and biomass linked onto carrier is about 76 mg of dry matter g⁻¹ of earthenware.So, our fluidized bed column is able to reduce 560 mg N---NO₃ h⁻¹ l⁻¹ of empty reactor, then retention time of liquid is less than 3 min.     

Combined FRM and GDFT filter bank designs for improved nonuniform DSA channelisation

Multistandard channelisation for base stations is a big application of generalised discrete Fourier transform modulated filter banks (GDFT‐FBs) in digital communications. For technologies such as software‐defined radio and cognitive radio, nonuniform channelisers must be used if frequency bands are shared by different standards. However, GDFT‐FB‐based nonuniform channelisers can suffer from high filter orders when applied to wideband input signals. In this paper, various combinations of GDFT‐FB with the frequency response masking technique are proposed and evaluated for both uniform and nonuniform channelisation applications. Results show that the proposed techniques achieve savings in both the number of filter coefficients and the number of operations per input sample. Copyright © 2015 John Wiley & Sons, Ltd.     

Urban regeneration policies and mental health in a context of economic crisis in Andalusia (Spain)

Literature suggests that urban regeneration policies might contribute towards improving mental health of residents, but to date there is a lack of empirical research on how these policies and downward social mobility can interact and influence health outcomes. The current study aims to explicitly test whether regeneration policies implemented in deprived Andalusian urban places (southern Spain) moderate the use of anxiolytics and/or antidepressants, taking into consideration families’ downward social mobility during the recent period of economic crisis in Spain. We designed a post intervention survey to retrospectively compare the evolution of psychotropic drug consumption in target and comparison areas. We observe a general increase in the use of anxiolytics and/or antidepressants from 2008 to 2015, specifically for people in whose families the economic crisis had the greatest impact (odds ratio?=?2.18; p value?<?0.001). However, better evolution is observed among residents of the target areas compared with residents of similar urban areas where this kind of polices have been not in force (odds ratio?=?0.50; p value?<?0.05). Therefore, urban regeneration policies might act as moderators of the risk of mental health, particularly when people are subject to the loss of individual/family resources in urban vulnerable contexts.

     

RESCUER: Development of a Modular Chemical,Biological, Radiological,and Nuclear Robot for Intervention,Sampling, and Situation Awareness*

This paper describes the development of a robot prototype for intervention, sampling, and situation awareness in CBRN (chemical, biological, radiological, and nuclear) missions. It outlines the mission requirements, design specifications, the solutions that were developed and integrated, and the final tests done. The solution addresses one of the most important mission requirements in CBRN scenarios: the capability to decontaminate the robot once it has been used in real missions. As microdoses of CBRN contaminants are sufficient to cause significant damage to human beings, prevention of robot contamination is always of top priority. If there is a potential danger of real contamination, it can only be removed by effective decontamination. The way to deal with this problem imposes significant design conditions; the proposed design allows an easy and fast decontamination of the robot. The work presents a new way to approach this kind of robot, based on modular component architecture over a robot operating system that permits the attachment and detachment of robot components via unique electromechanical interfaces. The resulting modular robot introduces an innovative kinematic solution that can be dynamically configured for the different mission requirements.     

Processing of graded anode-supported micro-tubular SOFCs based on samaria-doped ceria via gel-casting and spray-coating

A simple gel-casting method was successfully combined with the spray-coating technique to manufacture graded anode-supported micro-tubular solid oxide fuel cells (MT-SOFCs) based on samaria-doped ceria (SDC) as an electrolyte. Micro-tubular anodes were shaped by a gel-casting method based on a new and simple forming technique that operates as a syringe. The aqueous slurry formulation of the NiO–SDC substrate using agarose as a gelling agent, and the effect of spray-coating parameters used to deposit the anode functional layers (AFLs) and electrolyte were investigated. Furthermore, pre-sintering temperature of anode substrates was systematically studied to avoid the anode–electrolyte delamination and obtain a dense electrolyte without cracks, after co-sintering process at 1450 °C. Despite the high shrinkage of substrate (～70%), an anode porosity of ～37% was achieved. MT-SOFCs with ～2.5 mm of outer diameter, 370 μm thick substrate, 20 μm thick AFLs and 15 μm thick electrolyte were successfully obtained. The use of AFLs with 30:70 and 50:50 wt% NiO–SDC allowed to obtain a continuous gradation of composition and porosity in the anode–electrolyte interface.     

Effectiveness of traffic light vs. boom barrier controls at road–rail level crossings: A simulator study

Although collisions at level crossings are relatively uncommon occurrences, the potential severity of their consequences make them a top priority among safety authorities. Twenty-five fully-licensed drivers aged between 20 and 50 years participated in a driving simulator study that compared the efficacy, and drivers’ subjective perception, of two active level crossing traffic control devices: flashing lights with boom barriers and standard traffic lights. Because of its common usage in most states in Australia, a stop sign-controlled level crossing served as the passive referent. Although crossing violations were less likely at the level crossings controlled by active devices than at those controlled by stop signs, both kinds of active control were associated with a similar number of violations. Further, the majority (72%) of drivers reported preferring flashing lights to traffic lights. Collectively, results indicate that the installation of traffic lights at real-world level crossings would not be likely to offer safety benefits over and above those provided already by flashing lights with boom barriers. Furthermore, the high rate of violations at passively controlled crossings strongly supports the continued practice of upgrading level crossings with active traffic control devices.     

Effect of tower and nacelle on the flow past a wind turbine

Large eddy simulations (LES) of the flow past a wind turbine with and without tower and nacelle have been performed at 2 tip speed ratios (TSR, ), λ=3 and 6, where the latter corresponds to design conditions. The turbine model is placed in a virtual wind tunnel to reproduce the “Blind test 1” experiment performed at the Norwegian University of Science and Technology (NTNU) closed‐loop wind tunnel. The wind turbine was modeled using the actuator line model for the rotor blades and the immersed boundary method for the tower and nacelle. The aim of the paper is to highlight the impact of tower and nacelle on the turbine wake. Therefore, a second set of simulations with the rotating blades only (neglecting the tower and nacelle) has been performed as reference. Present results are compared with the experimental measurements made at NTNU and numerical simulations available in the literature. The tower and nacelle not only produce a velocity deficit in the wake but they also affect the turbulent kinetic energy and the fluxes. The wake of the tower interacts with that generated by the turbine blades promoting the breakdown of the tip vortex and increasing the mean kinetic energy flux into the wake. When tower and nacelle are modeled in the numerical simulations, results improve significantly both in the near wake and in the far wake.