Physical and mechanical characterisation of 3D-printed porous titanium for biomedical applications

The elastic modulus of metallic orthopaedic implants is typically 6–12 times greater than cortical bone, causing stress shielding: over time, bone atrophies through decreased mechanical strain, which can lead to fracture at the implantation site. Introducing pores into an implant will lower the modulus significantly. Three dimensional printing (3DP) is capable of producing parts with dual porosity features: micropores by process (residual pores from binder burnout) and macropores by design via a computer aided design model. Titanium was chosen due to its excellent biocompatibility, superior corrosion resistance, durability, osteointegration capability, relatively low elastic modulus, and high strength to weight ratio. The mechanical and physical properties of 3DP titanium were studied and compared to the properties of bone. The mechanical and physical properties were tailored by varying the binder (polyvinyl alcohol) content and the sintering temperature of the titanium samples. The fabricated titanium samples had a porosity of 32.2–53.4 % and a compressive modulus of 0.86–2.48 GPa, within the range of cancellous bone modulus. Other physical and mechanical properties were investigated including fracture strength, density, fracture toughness, hardness and surface roughness. The correlation between the porous 3DP titanium-bulk modulus ratio and porosity was also quantified.     

Role of Arachidonic Acid and Its Metabolites in the Biological and Clinical Manifestations of Idiopathic Nephrotic Syndrome

Studies concerning the role of arachidonic acid (AA) and its metabolites in kidney disease are scarce, and this applies in particular to idiopathic nephrotic syndrome (INS). INS is one of the most frequent glomerular diseases in childhood; it is characterized by T-lymphocyte dysfunction, alterations of pro- and anti-coagulant factor levels, and increased platelet count and aggregation, leading to thrombophilia. AA and its metabolites are involved in several biological processes. Herein, we describe the main fields where they may play a significant role, particularly as it pertains to their effects on the kidney and the mechanisms underlying INS. AA and its metabolites influence cell membrane fluidity and permeability, modulate platelet activity and coagulation, regulate lymphocyte activity and inflammation, preserve the permeability of the glomerular barrier, influence podocyte physiology, and play a role in renal fibrosis. We also provide suggestions regarding dietary measures that are able to prevent an imbalance between arachidonic acid and its parental compound linoleic acid, in order to counteract the inflammatory state which characterizes numerous kidney diseases. On this basis, studies of AA in kidney disease appear as an important field to explore, with possible relevant results at the biological, dietary, and pharmacological level, in the final perspective for AA to modulate INS clinical manifestations.     

A new gold(III)-aminoethyl imidazolium aurate salt as precursor for nanosized Au electrocatalysts

In this work the novel, robust, air- and moisture-stable gold(III)-aminoethyl imidazolium aurate salt [Cl₃AuNH₂(CH₂)₂ImMe][AuCl₄] (1) has been employed as precursor for the electrosynthesis of gold nanoparticles (AuNPs) onto ITO electrodes in 0.5 mol dm⁻³ H₂SO₄ aqueous solution without the use of additional additives and/or stabilizers. The electrode termed ILNH₂-Au_NPs200 prepared at a fixed electrodeposition time (t_d) of 200 s was characterized with AFM, SEM, XRD diffraction as well as cyclic voltammetry (CVs) and compared with an electrode in which the AuNPs have been electrodeposited from KAuCl₄ in the presence of KI as additive at the same t_d (Au_NPs200). The effect of the t_d (i.e. 50 s or 500 s; electrodes ILNH₂-Au_NPs50 and ILNH₂-Au_NPs500, respectively) was also investigated together with the electrocatalytic activity towards methanol oxidation in alkaline medium of all the prepared electrodes. The comparison with Au_NPs obtained with KI as additive shows that the presence of the amino-functionalized imidazolium moiety although not relevant in relation to the particle size, favours the metal electrodeposition process and plays an important role in the enhancement of the following parameters: (i) surface coverage (S.C.), (ii) electroactive particle coverage Φ_p %, (iii) electroactive surface area σ_red(exp)/σ_red(theor) and (iv) catalytic efficiency.     

Electrosynthesis of valuable conducting polymers from the anodic coupling of β-substituted oligothiophenes

Electrochemical polymerization of thiophene oligomers (n = 4) bearing an hexamethylenic ω-methoxy functionalized side chain at the 3-3″′ position of the thiophene rings, was performed in different solvents and electrode surfaces. The degree of polymerization and the electrochemical behaviour of the different electrosynthetized polymers were compared with a polymer obtained by a chemical method. The polymeric films were characterized using cyclic voltammetry, FT-IR, AFM and SEM microscopy.     

Characterisation of Argentinean honeys and evaluation of its inhibitory action on Escherichia coli growth

The aim of this work was to evaluate the physicochemical, sensory and Escherichia coli growth inhibitory characteristics of honey of different botanical sources from two geographic origin of Argentina. Honeys were obtained from apiaries located in two zones. The floral identification of honeys allowed to clustered them as monofloral, mixed and polyfloral honeys. The study of the physicochemical parameters such as colour, free acidity, pH and moisture showed that the last one reflected significant differences between honeys. These differences were markedly reflected in the average values of moisture content for each zone, being 18.96% and 14.29% to centre and east zone, respectively. In general, honeys evaluated presented an inhibitory effect on the E. coli growth at different periods of time (bacteriostatic action). Only, two of the samples would show a bactericide action against E. coli at 48 h of incubation. Honeys with higher non‐hydrogen peroxide activity, were collected from a same geographic place at the same season of year, showing a relationship between the antimicrobial activity and the geographic origin, which could be associated with the typical flora of the place.     

Analysis and framework-based design of a fault-tolerant web information system for m-health

The e-health domain has the objective to assist and manage citizens’ health. It concerns many actors like patient, doctors, hospitals and administration. Current and forthcoming generations of application will be web based and will integrate more and more mobile devices. In such application domain, called m-health, dependability is a key notion. In addition, more and more functionalities of such systems will be implemented as services for providing qualities like adaptability and maintainability. This paper presents, through a case study, how we can analyse and design an application that controls the insulin injection and that is embedded in a mobile device belonging to an e-health Web Information System (WIS). In order to ensure the dependability of the control systems, we show how to use Coordinated Atomic Actions (CAA). CAAs provide well defined concepts for fault tolerance, error-detection and error recovery in a distributed context where competitive and cooperative concurrencies are considered. The combination of CAA and SOA at design level it is proposed, with the purpose of being able to design systems that are partially implemented using service-oriented technologies. We updated and used our implementation framework, called CAA-DRIP, which originally was not tailored for service-oriented mobile applications. Thus, in this paper, we also propose an adaptation of CAA-DRIP for mobile devices.     

Rh(1%)@CexZr1−xO2–Al2O3 nanocomposites: Active and stable catalysts for ethanol steam reforming

Rh(1%)@Ce_xZr_1−xO₂–Al₂O₃ nanocomposites have been investigated as active and thermally stable catalysts for ethanol steam reforming. Preformed Rh nanoparticles have been efficiently protected from deactivation/sintering by a porous layer of nanocomposite oxides. Chemisorption and activity data confirm the good accessibility of the metal phase to the reaction mixture. No appreciable deactivation is observed after 160 h of reaction at 873 K. The ceria–zirconia mixed oxides favour reforming reactions, reduce coke formation and facilitate its removal. The alumina component is important to stabilize the ceria–zirconia mixed oxides, preventing their sintering.     

Purification and characterization of a peptide from Bacillus licheniformis showing dual antimicrobial and emulsifying activities

Bacillus licheniformis strain P40 produces a bacteriocin-like substance (BLS) that inhibits important pathogenic and food spoilage bacteria such as Listeria monocytogenes, Streptococcus spp., Bacillus cereus, and Erwinia carotovora. The antimicrobial peptide produced by B. licheniformis P40 was purified by ammonium sulfate precipitation, gel filtration chromatography on Sephadex G-100 and reversed phase chromatography on Source-RPC. The purification was about 100-fold with a yield of 0.3%. The molecular mass of the purified BLS about 800 Da, as determined by mass spectroscopy. The BLS was resistant for up to 100 °C and pH ranging 3–10, but lost its activity when treated with proteases and trichloroacetic acid. Reaction with ninhydrin produced the yellowish color instead the characteristic purple. Data from infrared spectroscopy also indicate the peptide is cyclic, resembling the lipopeptides surfactin and lichenisin. The BLS also showed emulsifying properties with several hydrophobic compounds, and dual antimicrobial and emulsifying activity in a meat model system. This antimicrobial peptide presents potential for use in as a food biopreservative or biodetergent.     

Common toads (Bufo arenarum) learn to anticipate and avoid hypertonic saline solutions.

Toads (Bufo arenarum) were exposed to pairings between immersion in a neutral saline solution (i.e., one that caused no significant variation in fluid balance), followed by immersion in a highly hypertonic saline solution (i.e., one that caused water loss). In Experiment 1, solutions were presented in a Pavlovian conditioning arrangement. A group receiving a single neutral-highly hypertonic pairing per day exhibited a greater conditioned increase in heart rate than groups receiving either the same solutions in an explicitly unpaired fashion, or just the neutral solution. Paired toads also showed a greater ability to compensate for water loss across trials than that of the explicitly unpaired group. Using the same reinforcers and a similar apparatus, Experiment 2 demonstrated that toads learn a one-way avoidance response motivated by immersion in the highly hypertonic solution. Cardiac and avoidance conditioning are elements of an adaptive system for confronting aversive situations involving loss of water balance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)