3 resultados para jet grouting
em CiencIPCA - Instituto Politécnico do Cávado e do Ave, Portugal
Resumo:
Poly(vinylidene fluoride-trifluoethylene) electrospun membranes were obtained from a blend of dimethylformamide (DMF) and methylethylketone (MEK) solvents. The inclusion of the MEK to the solvent system promotes a faster solvent evaporation allowing complete polymer crystallization during the jet travelling between the tip and the grounded collector. Several processing parameters were systematically changed to study their influence on fiber dimensions. Applied voltage and inner needle diameter do not have large influence on the electrospun fiber average diameter but in the fiber diameter distribution. On the other hand, the increase of the distance between the needle tip to collector results in fibers with larger average diameter. Independently on the processing conditions, all mats are produced in the electroactive phase of the polymer. Further, MC-3T3-E1cell adhesion was not inhibited by the fiber mats preparation, indicating their potential use for biomedical applications.
Resumo:
Poly(hydroxybutyrate) (PHB) obtained from sugar cane was dissolved in a blend of chloroform and dimethylformamide (DMF) and electrospun at 40 ºC. By adding DMF to the solution, the electrospinning process for the PHB polymer becomes more stable, allowing complete polymer crystallization during the jet travelling between the tip and the grounded collector. The influence of processing parameters on fiber size and distribution was systematically studied. It was observed that an increase of tip inner diameter promotes a decrease of the fiber average size and a broader distribution. On the other hand, an increase of the electric field and flow rate produces an increase of fiber diameter until a maximum of ~2.0 m, but for electric fields higher than 1.5 kV.cm-1, a decrease of the fiber diameter was observed. Polymer crystalline phase seems to be independent of the processing conditions and a crystallinity degree of 53 % was found. Moreover, thermal degradation of the as-spun membrane occurs in single step degradation with activation energy of 91 kJ/mol. Furthermore, MC-3T3-E1 cell adhesion was not inhibited by the fiber mats preparation, indicating their potential use for biomedical applications.
Resumo:
Olhemos para uma folha de São Paulo no meio do trânsito caótico e dos milhares de arranha-céus, enquanto passam centenas de buzinantes motoqueiros suicidas a uma velocidade estonteante… Depois de milhões de pessoas se terem manifestado no Brasil por causa de megas-processos de corrupção que têm sido descobertos, entre os quais o Petrolão, no qual as investigações apontam que a propina (suborno) foi o triplo do caso Mensalão, eis que a Presidenta Dilma avança para um pacote anti-corrupção. A operação Lava Jato já fala em milhares de milhões de reais. Mas, importante, é que apenas uma medida tem efeitos de aplicação imediata! São 7 as medidas. § Let us look for a Folha de Sao Paulo in the middle of chaotic traffic and thousands of skyscrapers, as they pass hundreds of suicide motorcycle at breakneck speed ... After millions of people have expressed in Brazil because of corruption mega-processes that have been discovered, including the Petrolão in which investigations indicate that the bribe (bribery) was triple the Mensalão case, behold, the President Dilma advances to an anti-corruption package. Operation Lava Jet is already talking about billions of reais. But, importantly, it is that only a measure takes effect immediately applicable! There are 7 steps.