Characterization of intermediate stages in the precipitation of hydroxyapatite at 37°C

Precipitation of hydroxyapatite Ca 5(PO 4) 3OH (HAp) was carried out by mixing a saturated calcium hydroxide aqueous solution with an orthophosphoric acid aqueous solution at 37°C. In order to promote optimal conditions for the production of HAp with high yields, mixing of the reaction medium was assured by a novel metal stirrer. Different experimental conditions were studied varying the mixing Ca/P molar ratio from 1 to 1.67. After process optimization, a suspension of HAp particles with pH close to 7 was obtained for a mixing molar ratio Ca/P=1.33. The precipitation process was then characterized as a function of pH and calcium concentration, revealing the existence of three different stages. The precipitate formed in each stage was characterized by scanning electron microscopy and X-ray diffraction.This work was supported by the Portuguese Foundation for Science and Technology (SFRH/BD/42992/2008) through the MIT-Portugal Program, Bioengineering Systems Focus Area. The authors are thankful to Dr. Jorge Ferreira from LNEG (Laboratorio Nacional de Energia e Geologia) for carrying out the X-ray measurements and their help with the interpretation of results

Synthesis, photochemical and in vitro cytotoxic evaluation of new iodinated aminosquaraines as potential sensitizers for photodynamic therapy

In this work, several benzothiazole-based aminosquaraine dyes, displaying strong absorption within the so-called phototherapeutic window (650–800 nm), were synthesized. The ability, of all the new dyes, to generate singlet oxygen was assessed by determining the correspondent phosphorescence emission and through the comparison with a standard. The quantum yields of singlet oxygen generation were determined and exhibited to be strongly dependent on the nature of the amino substituents introduced in the squaric ring. The photodynamic activity of the synthesized dyes was tested against four human tumor cell lines: breast (MCF-7), lung (NCI-H460), cervical (HeLa) and hepatocellular (HepG2) carcinomas; and a non-tumor porcine liver primary cell culture (PLP2). All the compounds synthesized were found to be able to inhibit tumor cells growth upon irradiation more than in the dark, in most of the cases, very significantly. Considering the photodynamic activity exhibited and the low toxicity displayed for the non-tumor cells, some of the synthetized dyes can be regarded as potential candidates as photosensitizers for PDT.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER for CIMO (UID/AGR/00690/2013) and CQ-VR (UID/QUI/00616/2013) financial support, as also for R. Calhelha contract.info:eu-repo/semantics/publishedVersio

Uso de microsistemas na precipitação em contínuo de hidroxiapatite

Neste trabalho é apresentado o estudo de dois microreatores ultrasónicos para a precipitação em contínuo de hidroxiapatite Ca5(PO4)3OH (HAp) a 37 º C. O primeiro reator consiste num microreator tubular imerso num banho ultrasónico, onde os fluxos laminar e segmentado (gás-líquido) foram ambos avaliados. De seguida, o estudo em regime laminar foi conduzido num novo dispositivo microfluídico desenvolvido no MIT. Este é constituído por uma pilha de placas de Teflon com um elemento piezoelétrico integrado, permitindo assim a transmissão direta de ultrassons para o reator. Para todos os microsistemas estudados foram obtidas nanopartículas de HAp, em condições próximas das condições fisiológicas de pH e temperatura. Além disso, as partículas produzidas apresentam-se sob a forma de bastonetes de aproximadamente 100 nm de comprimento e 20 a 50 nm de largura. Os microreatores utilizados produziram partículas de HAp num tempo muito curto e com maior cristalinidade, comparado com as partículas produzidas num reator batch. Também foi possível reduzir significativamente a agregação das partículas nos microsistemas, ao contrário do sistema batch, onde não foi possível evitar a formação de agregados.info:eu-repo/semantics/publishedVersio

Numerical study of the unsteady flow in simplified and realistic iliac bifurcation models

Cardiovascular diseases are a major cause of death and disability worldwide and they are commonly associated with the occurrence of atherosclerotic plaque deposition in the vessel walls, a process denoted as atherosclerosis. This is a chronic and progressive inflammatory disease of large-/medium-sized blood vessels that affects blood flow profiles, with the abdominal aorta and its branches being one of the locations prone to the development of this pathology, due to their curvatures and bifurcations. In this regard, the effect of flow patterns was studied and compared for both a simplified three-dimensional model of aorta bifurcation on the iliac arteries and a realistic model of iliac bifurcation, which was constructed from a computational tomography medical image. The flow patterns were analyzed in terms of velocity and wall shear stress distribution, but a special focus was given to the size and location of the recirculation zone. The simulations were performed using the Computational Fluid Dynamics software, FLUENT, taking into account the cardiac cycle profile at the infrarenal aorta. The shear stress and the velocity distribution observed for both models indicated that higher shear stress occurred along the flow divider wall (inner wall) and low shear stress occurred along the outer walls. In addition, the results demonstrated that the wall shear stress profiles were deeply affected by the transient profile of the cardiac cycle, with the deceleration phase being the most critical phase to the occurrence of backflow.This work was supported by FCT—Fundação para a Ciência e Tecnologia through the R&D Units Project Scope: UIDB/00319/2020, UIDB/04077/2020, and NORTE-01-0145-FEDER-030171, funded by COMPETE2020, NORTE 2020, PORTUGAL 2020, and FEDER

Process intensification and optimization for hydroxyapatite nanoparticles production

Precipitation processes are widely used in industry for the production of particulate solids. Efficient mixing of the reagents is of major importance for the chemical and physical nature of the synthesized particles. Recently, microreactors have been studied to overcome homogeneity problems found when using stirred tank batch reactors. The present work investigated an ultrasonic tubular microreactor for the continuous-flow precipitation of hydroxyapatite (HAp), both in single-phase flow (SPF) and in gas–liquid flow (GLF). HAp nanoparticles were yielded for both configurations under near-physiological conditions of pH and temperature. The as-prepared particles, especially those that were prepared under GLF, show improved characteristics compared to commercial powder or powder obtained in a stirred tank batch reactor. Primary particles are smaller, particle shape is more homogeneous, and the aggregation degree of the particles is lower

Functionalized asphalt mixtures: Photocatalytic, superhydrophobic and self-cleaning properties

Functionalization of road pavement asphalt mixtures provides new capabilities that can mitigate problems like air pollution and road accidents. In this research, nano-TiO2 and micro-ZnO were deposited through an aqueous solution by spraying it over the surface of asphalt mixture samples in order to promote the photocatalytic, superhydrophobic and self-cleaning capabilities. Tested by degradation of Rhodamine B, to assess the Photocatalytic Efficiency, and by Water Contact Angle (WCA), to assess the wettability of the materials, this technique can be used to promote these multifunctional capabilities in asphalt mixtures. With these enhanced surface characteristics, road safety and the environment, through pollutants degradation like NOx and SO2, will be improved.This work was supported by FCT—Fundação para a Ciência e Tecnologia—through the project PEst-OE/ECI/UI4047/2014info:eu-repo/semantics/publishedVersio

Boletus aereus growing wild in Serbia: chemical profile, in vitro biological activities, inactivation and growth control of food-poisoning bacteria in meat

Boletus aereus Bull. is a bolete, an edible mushroom frequently consumed all over the globe as a delicate mushroom, especially in Serbia, Portugal, Basque Country, Navarre, France and Italy. B. aereus was showed to be rich in carbohydrates (82.58 g/100 g dw), followed by proteins (7.86 g/100 g dw), ash (6.20 g/100 g dw) and fat (3.36 g/100 g dw). The most abundant sugar was identified as trehalose (11.28 g/100 g dw); three tocopherol isoforms (α-, β- and δ-tocopherols) were detected. Unsaturated fatty acids predominated over saturated fatty acids, with oleic and linoleic acids as the most dominant ones. p-Hydroxybenzoic (8.95 μg/100 g dw), p-coumaric (7.32 μg/100 g dw) and cinnamic (5.91 μg/100 g dw) acids were quantified, as also four organic acids: oxalic (0.69 g/100 g dw), citric (0.59 g/100 g dw), quinic (0.34 g/100 g dw), and fumaric (0.20 g/100 g dw) acids. The mushroom methanol extract showed in vitro antioxidant and antimicrobial activities, and successively inhibited the growth of meat contaminant bacteria, both at 25ºC and 4ºC, after 7 days of inoculation.The authors are grateful to Foundation for Science and Technology (FCT, Portugal) and COMPETE/QREN/EU for financial support to CIMO strategic project PEst-OE/AGR/UI0690/2011 and L. Barros contract. The authors also thank to SerbianMinistry of Education, Science and Technological Development for financial support (grant number 173032). The authors kindly thank to Nada Lazic for the harvest of the Boletus aereus sample

Quando o Intervalo QT é Curto Demais: Síncope Causada por Síndrome QT Curto

We report the case of a 52-year-old man who presented to our emergency department (ED) after three episodes of syncope in the seven hours before admission. During his stay in the ED he had recurrent ventricular tachycardia (VT) requiring external electrical cardioversion. A 12-lead electrocardiogram (ECG) showed a short QT (SQT) interval (270 ms, QTc 327 ms), with frequent R-on-T extrasystoles triggering sustained polymorphic VT. After exclusion of other precipitating causes, the patient was diagnosed as having SQT syndrome (SQTS) according to the Gollob criteria. To our knowledge, this is the first known documentation of an SQT-caused arrhythmic episode on a 12-lead ECG, as well as the first reported case of SQTS in Portugal. The patient received an implantable cardioverter-defibrillator and was discharged. At a follow-up assessment 14 months later he was symptom-free, interrogation of the device showed no arrhythmic events, and the ECG showed a QT interval of 320 ms (QTc 347 ms)