Deep metric learning for open-set human action recognition in videos

Neural Computing and Applications - Human action recognition (HAR) is a topic widely studied in computer vision and pattern recognition. Despite the success of recent models for this issue, most of...     

Factors affecting water colour removal by tyrosinase

Tyrosinase obtained from Agaricus bisporus was used to catalyze the decolourization of two reactive dyes: reactive yellow 15 (RY15) and reactive blue 114 (RB114). A 3³ factorial design was used to evaluate the effects of enzyme concentration, pH of the reaction medium and temperature on the decolourization yield. From fitted mathematical models, response surfaces were determined and the best decolourization conditions obtained were 25?°C, enzyme concentration of 200?U/L and pH 7.0. At these conditions, a maximum decolourization of 36 and 20% for RY15 and RB114, respectively, was obtained. In order to improve decolourization, aeration of the media, enzyme type (crude or lyophilized) and additives (CaCl₂ or CaCO₃) were evaluated. The lyophilized enzyme without any protective compound presented a better performance. The aeration was a very important factor confirming that oxygen was limiting the reaction. The aeration of the medium with lyophilized tyrosinase improves the dye decolourization to more than 90%.     

Electrodeposition of nanocrystalline copper thin films from 1-ethyl-3-methylimidazolium ethylsulphate ionic liquid

Copper thin films are increasingly important as interconnectors for the creation of smaller and better performing integrated circuits and electrodeposition from ionic liquid-based electrolytes could provide a greener fabrication method for these films. The electrodeposition of copper from copper(I) and copper(II) salt solutions in a low cost, widely available ionic liquid, 1-ethyl-3-methylimidazolium ethylsulphate, was studied using a range of different deposition potentials and temperatures. Three different electrolytes containing ~0.1 M of copper(I) chloride(CuCl), copper(II) chloride (CuCl₂) and copper(II) sulphate (CuSO₄) were used. Under similar deposition conditions, the films obtained from CuCl and CuSO₄-based electrolytes presented better continuity than films obtained from CuCl₂-based electrolyte. Continuous films with a homogeneous structure were obtained by electrodeposition from CuCl and CuSO₄-based solutions at a constant potential of ?1.8 V and a temperature of 35 °C. Under similar deposition parameters, the films deposited from CuCl₂-based electrolyte presented the largest particle size, while those deposited from copper(I) chloride and CuSO₄-based solutions presented finer microstructures. X-ray diffraction analysis and energy dispersive X-ray spectroscopy showed that the deposits were crystalline and consisted mainly of copper, with traces of oxygen and sulphur resulting from residues of the ionic liquid. The films presented a nanocrystalline microstructure consisting of particles about 25 nm, aggregated in clusters.     

Role of Cellulose Ether Polymers on Ibuprofen Release from Matrix Tablets

Cellulose derivatives are the most frequently used polymers in formulations of pharmaceutical products for controlled drug delivery. The main aim of the present work was to evaluate the effect of different cellulose substitutions on the release rate of ibuprofen (IBP) from hydrophilic matrix tablets. Thus, the release mechanism of IBP with methylcellulose (MC25), hydroxypropylcellulose (HPC), and hydroxypropylmethylcellulose (HPMC K15M or K100M) was studied. In addition, the influence of the diluents lactose monohydrate (LAC) and β-cyclodextrin (β-CD) was evaluated. Distinct test formulations were prepared containing: 57.14% of IBP, 20.00% of polymer, 20.29% of diluent, 1.71% of talc lubricants, and 0.86% of magnesium stearate as lubricants. Although non-negligible drug-excipient interactions were detected from DSC studies, these were found not to constitute an incompatibility effect. Tablets were examined for their drug content, weight uniformity, hardness, thickness, tensile strength, friability, porosity, swelling, and dissolution performance. Polymers MC25 and HPC were found to be unsuitable for the preparation of this kind of solid dosage form, while HPMC K15M and K100M showed to be advantageous. Dissolution parameters such as the area under the dissolution curve (AUC), the dissolution efficiency (DE_{20 h}), dissolution time (t 50%), and mean dissolution time (MDT) were calculated for all the formulations, and the highest MDT values were obtained with HPMC indicating that a higher value of MDT signifies a higher drug retarding ability of the polymer and vice-versa. The analysis of the drug release data was performed in the light of distinct kinetic mathematical models—Kosmeyer-Peppas, Higuchi, zero-, and first-order. The release process was also found to be slightly influenced by the kind of diluent used.     

Evaluation of the thixoformability of the A332 Alloy (Al–9.5?wt%Si–2.5?wt%Cu)

The main purpose of this article is to develop and/or use a commercial conventional low-cost raw material as thixoforming material in order to diminish the costs of the thixoforming process. Semi-solid technology usually uses aluminium low-silicon alloys such A356 (Al–7.0 wt%Si) as raw materials. High silicon content alloys with a quasi-eutectic composition diminish the semi-solid range, making it difficult to control the thixoforming temperature, although present excellent mechanical properties. This article reports on the semi-solid behaviour of Al–9.5 wt%Si–2.5 wt%Cu (A332). Thermo-Calc simulations and experimental DSC techniques were used to map the temperature transition from solid to liquid in order to achieve the best semi-solid behaviour and hence the best thixoforming temperature. Samples were reheated at three temperatures to 30, 45 and 60% of the solid fraction applying holding times of 0, 30, 90 and 210 s. The morphological evolution and semi-solid behaviour of the samples at these temperatures were determined via the fixed platen compression test. The structure showed the best semi-solid behaviour at 572 °C, with an apparent viscosity of up to 1.5 × 10⁵ Pa s. The results indicated that the semi-solid behaviour of the commertial Al–9.5 wt%Si–2.5 wt%Cu alloy is similar to that of the alloy A356. Despite its large dendritic structure it is possible, with the correct combination of temperature and time, to use this alloy as raw material for the thixoforming process. Furthermore, semi-solid parts can be produced by thixoforging using this low-cost material without any special preparation.     

Structure and water—oil emulsifying properties of asphaltenes

Alphaltenes were selected on the basis of their capacity to form water—oil emulsions. They were characterized by electron microscopy, surface group analysis, g.p.c. and low-angle X-ray scattering. It appears that the high stability of water-oil emulsions is related to the ‘structuring’ capacity of asphaltenes at the water-oil interface. Some asphaltenes are able to form regularly stacked layers, resembling the behaviour of surfactant liquid crystals.     

Use of a customized vision model to analyze the effects of higher-order ocular aberrations and neural filtering on contrast threshold performance

Customized optical filtering and light-dependent neural filtering were implemented in an ideal-observer model for an L-alternative forced-choice visual task. The model was applied to a contrast threshold visual task with adaptive optics correction of ocular higher-order (HO) aberrations under different light regimes, for which experimental data have previously been obtained (J. Mod. Opt.55, 791, 2008). A separability measure was used to assess the model-observer performance and to investigate the joint effect of optical and neural filtering. The numerical results were consistent with the experimental data in the assessment of the effect of HO aberrations as a function of light level.     

Transition from Cyclosporine-Induced Renal Dysfunction to Nephrotoxicity in an in Vivo Rat Model

Cyclosporin A (CsA), a calcineurin inhibitor, remain the cornerstone of immunosuppressive regimens, regardless of nephrotoxicity, which depends on the duration of drug exposure. The mechanisms and biomarkers underlying the transition from CsA-induced renal dysfunction to nephrotoxicity deserve better elucidation, and would help clinical decisions. This study aimed to clarify these issues, using a rat model of short- and long-term CsA (5 mg/kg bw/day) treatments (3 and 9 weeks, respectively). Renal function was assessed on serum and urine; kidney tissue was used for histopathological characterization and gene and/or protein expression of markers of proliferation, fibrosis and inflammation. In the short-term, creatinine and blood urea nitrogen (BUN) levels increased and clearances decreased, accompanied by glomerular filtration rate (GFR) reduction, but without kidney lesions; at that stage, CsA exposure induced proliferating cell nuclear antigen (PCNA), transforming growth factor beta 1 (TGF-β1), factor nuclear kappa B (NF-κβ) and Tumor Protein P53 (TP53) kidney mRNA up-regulation. In the long-term treatment, renal dysfunction data was accompanied by glomerular and tubulointerstitial lesions, with remarkable kidney mRNA up-regulation of the mammalian target of rapamycin (mTOR) and the antigen identified by monoclonal antibody Ki-67 (Mki67), accompanied by mTOR protein overexpression. Transition from CsA-induced renal dysfunction to nephrotoxicity is accompanied by modification of molecular mechanisms and biomarkers, being mTOR one of the key players for kidney lesion evolution, thus suggesting, by mean of molecular evidences, that early CsA replacement by mTOR inhibitors is indeed the better therapeutic choice to prevent chronic allograft nephropathy.