Synthesis and characterisation of large chlorapatite single-crystals with controlled morphology and surface roughness

This work describes the synthesis of chlorapatite single crystals using the molten salt method with CaCl₂ as a flux. By manipulating the processing conditions (amount of flux, firing time and temperature, and cooling rates) it is possible to manipulate the crystal morphology from microscopic fibres to large crystals (up to few millimetre long and ~100?μm thick). The crystal roughness can be controlled to achieve very flat surfaces by changing the melt composition “in situ” at high temperature. The Young modulus and hardness of the crystals are 110?±?15 and 6.6?±?1.5?GPa respectively as measured by nanoindentation. Crystal dissolution in Hanks solution starts around the defects. Several in vitro assays were performed; ClAp crystals with different size and shape are biocompatible. Cell apoptosis was very low at 5, 10, and 15?days (Caspase-3) for all the samples. Proliferation (MTT) showed to be influenced by surface roughness and size of the crystals.     

Combining discriminative spatiotemporal features for daily life activity recognition using wearable motion sensing suit

Motion sensing plays an important role in the study of human movements, motivated by a wide range of applications in different fields, such as sports, health care, daily activity, action recognition for surveillance, assisted living and the entertainment industry. In this paper, we describe how to classify a set of human movements comprising daily activities using a wearable motion capture suit, denoted as FatoXtract. A probabilistic integration of different classifiers recently proposed is employed herein, considering several spatiotemporal features, in order to classify daily activities. The classification model relies on the computed confidence belief from base classifiers, combining multiple likelihoods from three different classifiers, namely Naïve Bayes, artificial neural networks and support vector machines, into a single form, by assigning weights from an uncertainty measure to counterbalance the posterior probability. In order to attain an improved performance on the overall classification accuracy, multiple features in time domain (e.g., velocity) and frequency domain (e.g., fast Fourier transform), combined with geometrical features (joint rotations), were considered. A dataset from five daily activities performed by six participants was acquired using FatoXtract. The dataset provided in this work was designed to be extremely challenging since there are high intra-class variations, the duration of the action clips varies dramatically, and some of the actions are quite similar (e.g., brushing teeth and waving, or walking and step). Reported results, in terms of both precision and recall, remained around 85 %, showing that the proposed framework is able to successfully classify different human activities.     

Metabolite profiling of human amniotic fluid by hyphenated nuclear magnetic resonance spectroscopy

The metabolic profiling of human amniotic fluid (HAF) is of potential interest for the diagnosis of disorders in the mother or the fetus. In order to build a comprehensive metabolite database for HAF, hyphenated NMR has been used, for the first time, for systematic HAF profiling. Experiments were carried out using reverse-phase (RP) and ion-exchange liquid chromatography (LC), in order to detect less and more polar compounds, respectively. RP-LC conditions achieved good separation of amino acids, some sugars, and xanthines. Subsequent NMR and MS analysis enabled the rapid identification of 30 compounds, including 3-methyl-2-oxovalerate and 4-aminohippurate identified in HAF for the first time, to our knowledge. Under ion-exchange LC conditions, a different set of 30 compounds was detected, including sugars, organic acids, several derivatives of organic acids, and amino acids. In this experiment, five compounds were identified for the first time in HAF: D-xylitol, amino acid derivatives (N-acetylalanine, N-acetylglycine, 2-oxoleucine), and isovalerate. The nonendogenous nature of some metabolites (caffeine, paraxanthine, D-xylitol, sorbitol) is discussed. Hyphenated NMR has allowed the rapid detection of approximately 60 metabolites in HAF, some of which are not detectable by standard NMR due to low abundance (microM) and signal overlap thus enabling an extended metabolite database to be built for HAF.     

An efficient method for segmentation of images based on fractional calculus and natural selection

Image segmentation has been widely used in document image analysis for extraction of printed characters, map processing in order to find lines, legends, and characters, topological features extraction for extraction of geographical information, and quality inspection of materials where defective parts must be delineated among many other applications. In image analysis, the efficient segmentation of images into meaningful objects is important for classification and object recognition. This paper presents two novel methods for segmentation of images based on the Fractional-Order Darwinian Particle Swarm Optimization (FODPSO) and Darwinian Particle Swarm Optimization (DPSO) for determining the n-1 optimal n-level threshold on a given image. The efficiency of the proposed methods is compared with other well-known thresholding segmentation methods. Experimental results show that the proposed methods perform better than other methods when considering a number of different measures.     

Molecular basis for the generation in pigs of influenza A viruses with pandemic potential

Genetic and biologic observations suggest that pigs may serve as "mixing vessels" for the generation of human-avian influenza A virus reassortants, similar to those responsible for the 1957 and 1968 pandemics. Here we demonstrate a structural basis for this hypothesis. Cell surface receptors for both human and avian influenza viruses were identified in the pig trachea, providing a milieu conducive to viral replication and genetic reassortment. Surprisingly, with continued replication, some avian-like swine viruses acquired the ability to recognize human virus receptors, raising the possibility of their direct transmission to human populations. These findings help to explain the emergence of pandemic influenza viruses and support the need for continued surveillance of swine for viruses carrying avian virus genes.     

Bio-inspired porous SiC ceramics loaded with vancomycin for preventing MRSA infections

Implant-related infections are a serious complication in orthopaedic and dental surgery resulting in prolonged hospitalization, high medical costs and patient mortality. The development of porous implants loaded with antibiotics may enable a local delivery for preventing surface colonization and biofilm formation. A new generation of bio-derived porous ceramic material that mimics hierarchical structures from Nature was evaluated. Silicon carbide ceramics derived from Sapelli wood (bioSiC) were obtained by pyrolysis of Entandrophragma cylindricum wood followed by infiltration with molten silicon. This process renders disks that keep the bimodal pore size distribution (3 and 85 μm) of the original material and are highly cytocompatible (BALB/3T3 cell line). The ability of the bio-ceramic to load the antimicrobial agent vancomycin was evaluated by immersion of disks in drug solutions covering a wide range of concentrations. The disks released at pH 7.4 an important amount of drug during the first 2 h (up to 11 mg/g bioSiC) followed by a slower release, which is related to the presence of macro- and mesopores. Finally, the anti-biofilm effect against methicillin resistant Staphylococcus aureus was assessed and a considerable reduction (92%) of the bacterial film was observed. Results highlight the bioSiC potential as component of medicated medical devices.