7 resultados para válvula de Eustáquio
em Repositório da Produção Científica e Intelectual da Unicamp
Resumo:
From December-1965 to November-1969, 95 hydrocephalic infants have been operated upon using ventriculoperitoneal shunt with valve (88 cases with a Spitz-Holter valve, 6 cases with a Hakim valve and one case with a Pudenz-Heyer valve). Up to the present time (December, 1970) a total of 54 children are alive with a compensated hydrocephalus and 9 patients died, being impossible to follow-up the 32 remaining cases. The use of the ventriculoperitoneal shunt has eliminated all cardiovascular-pulmonary complications and reduced the number for surgical revisions. Besides, infections involving the draining system are less severe and more easily controlled than those occurring in the ventriculoatrial shunts. After analysis of the surgical techniques as well as complications and results the following conclusions are stated: 1) the use of a valve in the ventriculoperitoneal shunt difficults the oclusion of the peritoneal end of the draining system; 2) good results can be expected without reoperations in about 42,35% of hydrocephalus cases treated by ventriculoperitoneal shunt with valve; 3) ventriculoperitoneal shunts with valve showed better results when compared to ventriculoatrial shunts. This statement is made comparing two groups of hydrocephalic infants submitted to surgery at the same Service and in the same conditions, with the same follow-up period; 4) the cases presented permit to state that at present time the ventriculoperitoneal shunt with valve is the most suitable surgical procedure for hydrocephalus.
Resumo:
Negative-ion mode electrospray ionization, ESI(-), with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was coupled to a Partial Least Squares (PLS) regression and variable selection methods to estimate the total acid number (TAN) of Brazilian crude oil samples. Generally, ESI(-)-FT-ICR mass spectra present a power of resolution of ca. 500,000 and a mass accuracy less than 1 ppm, producing a data matrix containing over 5700 variables per sample. These variables correspond to heteroatom-containing species detected as deprotonated molecules, [M - H](-) ions, which are identified primarily as naphthenic acids, phenols and carbazole analog species. The TAN values for all samples ranged from 0.06 to 3.61 mg of KOH g(-1). To facilitate the spectral interpretation, three methods of variable selection were studied: variable importance in the projection (VIP), interval partial least squares (iPLS) and elimination of uninformative variables (UVE). The UVE method seems to be more appropriate for selecting important variables, reducing the dimension of the variables to 183 and producing a root mean square error of prediction of 0.32 mg of KOH g(-1). By reducing the size of the data, it was possible to relate the selected variables with their corresponding molecular formulas, thus identifying the main chemical species responsible for the TAN values.
Resumo:
Antimony is a common catalyst in the synthesis of polyethylene terephthalate used for food-grade bottles manufacturing. However, antimony residues in final products are transferred to juices, soft drinks or water. The literature reports mentions of toxicity associated to antimony. In this work, a green, fast and direct method to quantify antimony, sulfur, iron and copper, in PET bottles by X-ray fluorescence spectrometry is presented. 2.4 to 11 mg Sb kg-1 were found in 20 samples analyzed. The coupling of the multielemental technique to chemometric treatment provided also the possibility to classify PET samples between bottle-grade PET/recycled PET blends by Fe content.
Resumo:
The present work aimed the development of a low cost servo-valve that answers to an electronic control signal, for variable rates liquid inputs application. A literature research to define which valve type should be used was made. A mechanically activated proportional valve with an electronically controlled servo-engine was designed and evaluated. Since developed the servo-valve, the system was submited to a number of tests .The evaluation of its behavior was obtained in terms of repeatability, hystheresis and linearity. The test was accomplished in a bench, specially developed for this aim. As a result, were obtained three curves of opening percentage as function of flow rate, describing three opening and closing increments in two different work pressures. The servo-valve presented a good repeatability, reasonable hysteresis and a typically quadratic curve. This one maintained the low cost target. These results were very satisfied because the non-linearity and the hysteresis could be easily corrected by software.
Resumo:
Universidade Estadual de Campinas . Faculdade de Educação Física
Resumo:
Universidade Estadual de Campinas . Faculdade de Educação Física
Resumo:
Universidade Estadual de Campinas. Faculdade de Educação Física