Atomic Force Microscopy - Laser Scanning Confocal Microscopy imaging protocol for copepod fecal pellets

Within the marine carbon and nitrogen biogeochemical cycles, fecal pellets produced by pelagic and benthic copepods are important microbial activity hotspots as particle substrate for bacteria colonization and as sources of particulate and dissolved organic C and N. We developed a protocol combining Atomic Force Microscopy (AFM) and Laser Scanning Confocal Microscopy (LSCM) to study the peritrophic membrane structure and associated bacteria of fecal pellets produced by a benthic copepod, Paramphiascella fulvofasciata. AFM imaging revealed a fibrillar network structure of the peritrophic membrane, 0.7-5.9 nm thick similar to marine polysaccharides and a-chitin. Bacterial cell volume range was 0.006-0.117 µm3 in liquid. LSCM imaging showed a 3D-heterogeneous microenvironment. This protocol would allow high-resolution interrogation of structural changes and bacterial dynamics within the copepod fecal pellets and other heterogeneous particles such marine snow under environmental conditions

Heat Treated NiP–SiC Composite Coatings: Elaboration and Tribocorrosion Behaviour in NaCl Solution

Tribocorrosion behaviour of heat-treated NiP and NiP–SiC composite coatings was investigated in a 0.6 M NaCl solution. The tribocorrosion tests were performed in a linear sliding tribometer with an electrochemical cell interface. It was analyzed the influence of SiC particles dispersion in the NiP matrix on current density developed, on coefficient of friction and on wear volume loss. The results showed that NiP–SiC composite coatings had a lower wear volume loss compared to NiP coatings. However, the incorporation of SiC particles into the metallic matrix affects the current density developed by the system during the tribocorrosion test. It was verified that not only the volume of co-deposited particles (SiC vol.%) but also the number of SiC particles per coating area unit (and consequently the SiC particles size) have made influence on the tribocorrosion behaviour of NiP–SiC composite coatings

Hybrid stars with sequential phase transitions: the emergence of the g2_2 mode

Neutron stars are the densest objects in the Universe, with $M \sim 1.4 M_{\odot}$ and $R \sim 12$ km, and the equation of state associated to their internal composition is still unknown. The extreme conditions to which matter is subjected inside neutron stars could lead to a phase transition in their inner cores, giving rise to a hybrid compact object. The observation of $2M_{\odot}$ binary pulsars (PSR~J1614-2230, PSR~J0343$+$0432 and PSR~J0740$+$6620) strongly constraints theoretical models of the equation of state. Moreover, the detection of gravitational waves emitted during the binary neutron star merger, GW170817, and its electromagnetic counterpart, GRB170817A, impose additional constraints on the tidal deformability. In this work, we investigate hybrid stars with sequential phase transitions hadron-quark-quark in their cores. We assume that both phase transitions are sharp and analyse the rapid and slow phase conversion scenarios. For the outer core, we use modern hadronic equations of state. For the inner core we employ the constant speed of sound parametrization for quark matter. We analyze more than 3000 hybrid equations of state, taking into account the recent observational constraints from neutron stars. The effects of hadron-quark-quark phase transitions on the normal oscillation modes $f$ and $g$, are studied under the Cowling relativistic approximation. Our results show that, in the slow conversion regime, a second quark-quark phase transition gives rise to a new $g_2$~mode. We discuss the observational implications of our results associated to the gravitational waves detection and the possibility of detecting hints of sequential phase transitions and the associated $g_2$~mode.Comment: 24 pages, 9 figure

Integrating sol-gel and carbon dots chemistry for the fabrication of fluorescent hybrid organic-inorganic films

Highly fluorescent blue and green-emitting carbon dots have been designed to be integrated into sol-gel processing of hybrid organic-inorganic materials through surface modification with an organosilane, 3-(aminopropyl)triethoxysilane (APTES). The carbon dots have been synthesised using citric acid and urea as precursors; the intense fluorescence exhibited by the nanoparticles, among the highest reported in the scientific literature, has been stabilised against quenching by APTES. When the modification is carried out in an aqueous solution, it leads to the formation of silica around the C-dots and an increase of luminescence, but also to the formation of large clusters which do not allow the deposition of optically transparent films. On the contrary, when the C-dots are modified in ethanol, the APTES improves the stability in the precursor sol even if any passivating thin silica shell does not form. Hybrid films containing APTES-functionalized C-dots are transparent with no traces of C-dots aggregation and show an intense luminescence in the blue and green range

Comparação de percentuais de gordura corporal, utilizando impedância bioelétrica e a equação de Deurenberg

Com o crescimento da população obesa e com sobrepeso, o IMC (Índice de Massa Corporal) passou a ser uma análise amplamente empregada para resultados e classificações de composição corporal dada a simplicidade e exeqüibilidade do método. Erros inerentes ao IMC fomentam a utilização de outras ferramentas para a tomada de parâmetros corporais de relevância para a clínica assim como a porcentagem de gordura corporal. No pressente estudo realizamos uma comparação de reprodutibilidade dos resultados obtidos para o percentual de gordura corporal pelo método de impedância bioelétrica e pelo IMC corrigido pela Equação de Deurenberg. Os testes foram aplicados em 25 indivíduos (5 homens e 20 mulheres) com idade entre 17 a 75 anos. Os resultados obtidos apontam uma excelente correspondência e reprodutibilidade entre os métodos utilizados (r = 0,906). Estes dados iniciais sugerem a possibilidade de utilização destes índices para o diagnóstico de gordura corporal em percentagem, com a possibilidade de aplicação clínica

Proposal of a Micro Generator Piezoelectric for Portable Devices from the Energy Harvesting

Abstract. This paper presents a proposal for clean energy generation through the Piezoelectricity PZT via piezoelectric cells tha

Prototype of a Reduced Scale of a Refrigeration System of Environments Controlled with Pulse Width Modulation (PWM) Using Thermoelectric Modules by Peltier Effect

Abstract. This paper presents the design of a scaled-down prototype of a proposed for a cooling system on environments for replacement of air conditioners by compressor