Caracterização da liga Ti-30Ta após tratamento biomimético associado à incorporação de antibiótico

Surface treatments have been used to modify the surface of titanium alloys. The purpose of this study is to evaluate the surface of Ti-30Ta alloy after biomimetic approach associated to antibiotic incorporation. The ingots were obtained in arc melting furnace, treated and cold-worked by swaging. The surface treatment was performed in two steps: biomimetic treatment and antibiotic incorporation. For biomimetic treatment, first an alkaline treatment (NaOH 1M at 60ºC) was performed, followed by heat treatment and immersion in SBFx5 (Simulated Body Fluid) for a period of 24 hours. In order to incorporate the antibiotic, samples were immersed in a solution formed by drugs plus SBFx5 for 48 hours. The sample surfaces were analyzed by scanning electron microscopy (SEM), X-Ray diffraction (XRD), atomic force microscopy (AFM) and contact angle measurements. The release of antibiotic from coated implants was measured in phosphate buffer saline at pH 7.4 by using UV/VIS spectrometry. Results have shown changes on the surface after incorporating the drug, which is gradually co-precipitated with the Ca-P crystals, forming a uniform and rough layer on the metal surface

Caracterização da liga Ti-15Zr visando aplicações biomédicas

With advances in health care, has been na increase of demand for material that could replace the functions of the human body parts, thus evolved biomedic prosthesis which today are responsible for the constant improvement of the quality of life. The Titanium alloys are widely used as implants due to its properties, like high mechanical resistance, biocompatibility and corrosion resistance, and the addition alloying elements like Zirconium, may improve some of those properties. Such properties are related to the microstructure and consequently to the type of processing performed. The purpose of this dissertation was to characterize the experimental alloy Ti15Zr after route of processsing and heat treatment in order to extend the knowledge about this alloy. The latter has been abtained by fusion of pure metals in a arc melting furnace with an inert argon atmosphere. The material has been homogenized in a tube furnace at 950ºC for 24h and cold worked by swaging, after that, bars with 10 mm of diameter were obtained by the process of rotary forging. The samples were solubilized at 900º C for 2 hours and quenched in water. After that, 4 samples were submitted to the aging, at 400º C, 450º C, 500º C and 550º C. The microstructure and phase analysis was done by optical microscopy and X-rays diffraction (XRD), the mechanical characterization was carried out by microhardness test and finally, evaluation of corrosion resistance of the alloy by electrochemical tests. The XRD and the optical microscopy made it possible to analyze that the heat treatment influenced the phase shifting from α to α', and probably affected the alloy hardness, at the first aged sample at 500º Chas been a sudden increase in the value of hardness, probably by appearance of omega phase, unwanted phase to the medical application duo to great fragility, and finally ... (Complete abstract click electronic access below)

Radiative association of Ti and O atoms

Rate coefficients for the radiative association of titanium and oxygen atoms to form the titanium monoxide (TiO) molecule are estimated. The radiative association of Ti(F-3) and O(P-3) atoms is dominated by an approach along the C-3 Delta potential energy curve, accompanied by spontaneous emission into the X-3 Delta ground state of TiO. For temperatures ranging from 300-14 000 K, the total rate coefficients are found to vary from 4.76 x 10(-17) to 9.96 x 10(-17) cm(3) s(-1), respectively.

On the electrical conductivity of Ti-implanted alumina

Ion implantation of metal species into insulators provides a tool for the formation of thin, electrically conducting, surface layers with experimenter-controlled resistivity. High energy implantation of Pt and Ti into alumina accelerator components has been successfully employed to control high voltage surface breakdown in a number of cases. In the work described here we have carried out some basic investigations related to the origin of this phenomenon. By comparison of the results of alumina implanted with Ti at 75 keV with the results of prior investigations of polymers implanted with Pt at 49 eV and Au at 67 eV, we describe a physical model of the effect based on percolation theory and estimate the percolation parameters for the Ti-alumina composite. We estimate that the percolation dose threshold is about 4 x 10(16) cm(-2) and the maximum dose for which the system remains an insulator-conductor composite is about 10 x 10(16) cm(-2). The saturation electrical conductivity is estimated to be about 50 S/m. We conclude that the observed electrical conductivity properties of Ti-implanted alumina can be satisfactorily described by percolation theory. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697900]

Characterization of a new beta titanium alloy, Ti-12Mo-3Nb, for biomedical applications

In recent years, different beta titanium alloys have been developed for biomedical applications with a combination of mechanical properties including a low Young's modulus, high strength, fatigue resistance and good ductility with excellent corrosion resistance. From this perspective, a new metastable beta titanium Ti-12Mo-3Nb alloy was developed with the replacement of both vanadium and aluminum from the traditional Ti-6Al-4V alloy. This paper presents the microstructure, mechanical properties and corrosion resistance of the Ti-12Mo-3Nb alloy heat-treated at 950 degrees C for 1 h. The material was characterized by X-ray diffraction and by scanning electron microscopy. Tensile tests were carried out at room temperature. Corrosion tests were performed using Ringer's solution at 25 degrees C. The results showed that this alloy could potentially be used for biomedical purposes due to its good mechanical properties and spontaneous passivation. (c) 2011 Elsevier B.V. All rights reserved.

Uso da monitorização hemodinâmica contínua não invasiva na insuficiência cardíaca descompensada

FUNDAMENTO: A avaliação clínico-hemodinâmica à beira do leito e o uso do cateter de artéria pulmonar para a estimativa de dados hemodinâmicos têm sido utilizados na insuficiência cardíaca descompensada. Entretanto, não existem dados com o uso da monitorização hemodinâmica contínua não invasiva. OBJETIVO: Comparar as medidas obtidas com a monitorização hemodinâmica não invasiva com as invasivas em pacientes com insuficiência cardíaca descompensada e refratária ao tratamento. MÉTODOS: As medidas hemodinâmicas não invasivas foram obtidas através da monitorização contínua da pressão arterial sistêmica pelo modelo de ondas de pulso (modelflow) e foram comparadas com as medidas obtidas pela passagem do cateter de artéria pulmonar, simultaneamente. RESULTADOS: Foram realizadas 56 medidas em 14 pacientes estudados em dias e horários diferentes. O índice de correlação entre as medidas da pressão arterial sistólica foi de r = 0,26 (IC 95% = 0,00 a 0,49, p = 0,0492) e da diastólica de r = 0,50 (IC 95% = 0,27 a 0,67, p < 0,0001). A correlação foi de r = 0,55 (IC 95% = 0,34 a 0,71, p 0,0001) para o índice cardíaco e de r = 0,32 (IC 95% = 0,06 a 0,53, p = 0,0178) para a resistência vascular sistêmica. CONCLUSÃO: Houve correlação entre as medidas hemodinâmicas não invasivas quando comparadas às medidas do cateter de artéria pulmonar. A monitorização hemodinâmica contínua não invasiva pode ser útil para pacientes internados com insuficiência cardíaca descompensada.

Monitorização de eletrólitos urinários em pacientes críticos: estudo preliminar observacional

OBJETIVO: Sobreviventes e não sobreviventes da unidade de terapia intensiva apresentam perfis ácido-básicos distintos. A regulação renal de eletrólitos urinários e a diferença de íons fortes urinários têm papéis principais na homeostase ácido- básica. O objetivo deste estudo foi avaliar a potencial utilidade da mensuração diária dos eletrólitos urinários na monitorização ácido-básica e da função renal. MÉTODOS: Foram registrados, prospectivamente e diariamente, parâmetros ácido-básicos plasmáticos e marcadores tradicionais da função renal, em paralelo à medição dos eletrólitos urinários em pacientes com sonda vesical internados na unidade de terapia intensiva. Os pacientes que permaneceram na unidade de terapia intensiva com sonda vesical por pelo menos 4 dias foram incluídos neste estudo. RESULTADOS: Dos 50 pacientes incluídos neste estudo, 22% vieram a óbito durante a internação na unidade de terapia intensiva. A incidência de lesão renal aguda foi significativamente maior nos não sobreviventes, durante os 4 dias de observação (64% versus 18% em sobreviventes). O cloreto e o sódio urinário foram mais baixos, e a diferença de íons fortes urinários mais alta, no 1º dia, em pacientes que desenvolveram lesão renal aguda tanto nos sobreviventes como nos não sobreviventes. Ambos os grupos tiveram débito urinário semelhante, embora os não sobreviventes tenham apresentado diferença de íons fortes urinários persistentemente mais alta durante o período de observação. Os sobreviventes apresentaram melhoria progressiva no perfil metabólico ácido-básico devido ao aumento, no plasma, da diferença de íons fortes e à diminuição dos ácidos fracos. Essas mudanças foram concomitantes à diminuição da diferença de íons fortes urinários. Com relação aos não sobreviventes, os parâmetros ácido-básicos não tiveram alteração significativa durante o seguimento. CONCLUSÃO: A avaliação diária dos eletrólitos urinários e da diferença de íons fortes urinários é útil para a monitorização ácido-básica e da função renal em pacientes críticos, tendo perfis distintos entre sobreviventes e não sobreviventes na unidade de terapia intensiva.

O gerente de projetos de TI em organizações com níveis de maturidade diferenciados

A literatura sobre gestão de projetos mostra, de forma recorrente, a importância da figura do gerente no desempenho dos projetos. O presente artigo apresenta os resultados de um levantamento (survey) do papel do gerente de projetos de TI como elemento condicionante do desempenho desses projetos. Os resultados encontrados mostram que a relação do gerente de projetos com o desempenho dos projetos é alterada pelo nível de maturidade da organização executante em gestão de projetos. Nas organizações com menor maturidade existe uma relação muito mais forte do perfil do gerente com o desempenho dos projetos.Isso sugere que as organizações que conseguem estimular sua maturidade em gestão de projetos criam condições para que o desempenho de seus projetos fique menos dependente da ação individual dos gerentes.

Influence of the substitutional solute on the mechanical properties of Ti-Nb binary alloys for biomedical use

Titanium alloys are widely used in the manufacture of biomedical implants because they possess an excellent combination of physical properties and outstanding biocompatibility. Today, the most widely used alloy is Ti-6Al-4V, but some studies have reported adverse effects with the long-term presence of Al and V in the body, without mentioning that the elasticity modulus value of this alloy is far superior to the bone. Thus, there is a need to develop new Ti-based alloys without Al and V that have a lower modulus, greater biocompatibility, and similar mechanical strength. In this paper, we investigated the effect of Nb as a substitutional solute on the mechanical properties of Ti-Nb alloys, prepared in an arc-melting furnace and characterized by density, X-ray diffraction, optical microscopy, hardness and elasticity modulus measurements. The X-ray and microscopy measurements show a predominance of the α phase. The microhardness values showed a tendency to increase with the concentration of niobium in the alloy. Regarding the elasticity modulus, it was observed a nonlinear behavior with respect to the concentration of niobium. This behavior is associated with the presence of the α phase.

Dynamical Elastic Moduli of the Ti-13Nb-13Zr biomaterial alloy by mechanical spectroscopy

Dynamical Elastic Moduli of the Ti-13Nb-13Zr biomaterial alloy were obtained using the mechanical spectroscopy technique. The sample with heat treatment at 1170K for 30 minutes and water quenched with subsequent aging treatment at 670 K for 3 hours (TNZ + WQ + 670 K/3 h), was characterized through decay of free oscillations of the sample in the flexural vibration mode. The spectra of anelastic relaxation (internal friction and frequency) in the temperature range from 300 K to 625 K not revealed the presence of relaxation process. As shown in the literature, the hcp structure usually does not exhibit any relaxation due to the symmetry of the sites in the crystalline lattice, but if there is some relaxation, this only occurs in special cases such as low concentration of zirconium or saturation of the stoichiometric ratio of oxygen for zirconium. Dynamical elastic modulus obtained for TNZ + WQ + 670 K/3 h alloy was 87 GPa at room temperature, which is higher than the value for Ti-13Nb-13Zr alloy (64 GPa) of the literature. This increment may be related to the change of the proportion of α and β phases. Besides that, the presence of precipitates in the alloy after aging treatment hardens the material and reduces its ductility.

On Ti-18Si-6B and Ti-7.5Si-22.5B powder alloys prepared by high-energy ball milling and sintering

Recently, a new ternary phase was discovered in the Ti-Si-B system, located near the Ti6Si2B composition. The present study concerns the preparation of titanium alloys that contain such phase mixed with α-titanium and other intermetallic phases. High-purity powders were initially processed in a planetary ball-mill under argon atmosphere with Ti-18Si-6B and Ti-7.5Si-22.5B at. (%) initial compositions. Variation of parameters such as rotary speed, time, and ball diameters were adopted. The as-milled powders were pressureless sintered and hot pressed. Both the as-milled and sintered materials were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometry. Sintered samples have presented equilibrium structures formed mainly by the α-Ti+Ti6Si2B+Ti5Si3+TiB phases. Silicon and boron peaks disappear throughout the milling processes, as observed in the powder diffraction data. Furthermore, an iron contamination of up to 10 at. (%) is measured by X-ray spectroscopy analysis on some regions of the sintered samples. Density, hardness and tribological results for these two compositions are also presented here.

L’influenza del trattamento superficiale di pallinatura sulle prestazioni a fatica della lega Ti-6Al-4V

In questa tesi sono stati studiati i dati presenti in letteratura sugli gli effetti benefici sulla vita a fatica della lega Ti6Al4V del processo di pallinatura,con particolare interesse agli effetti sul processo della dimensione dei pallini e della durata del processo. Inoltre si sono analizzati i dati di letteratura riguardanti l'incremento di vita a fatica della lega Ti6Al4V ottenuto tramite il processo di ripallinatura e la relazione tra pallinatura,ripallinatura e fretting fatigue. Infine sono stati esaminati i dati sul comportamento a fatica della lega Ti6Al4V grado ELI per uso biomedico sottoposta a carico oligociclico ed ad alto numero di cicli.

Il sistema mg-ti nanostrutturato per lo stoccaggio d'idrogeno allo stato solido

Nella presente tesi ci si pone lo scopo di studiare stabilità, ciclabilità e cinetica di campioni composti da magnesio e titanio (Mg-Ti) prodotti con la tecnica della condensazione in gas inerte (IGC) per lo di stoccaggio di idrogeno. Il sistema Mg-Ti sembra essere un buon candidato per poter costruire serbatoi di idrogeno allo stato solido sia per applicazioni fisse che mobili. La ricerca di tecnologie efficaci per immagazzinare idrogeno è fondamentale per poter affermare un ciclo energetico sostenibile, svincolato dai combustibili fossili. Sia il lavoro di crescita dei campioni all'Università di Bologna, sia la caratterizzazione di questi nei laboratori dell' Institut de Chimie et des Materiaux Paris-Est (ICMPE) si collocano all'interno del progetto europeo COST per la ricerca di materiali nanostrutturati destinati ad applicazioni nel campo dello stoccaggio dell'energia in forma di idrogeno allo stato solido.

Development and evaluation of a 44 Ti, 44 Sc radionuclide generator and labeling of biomolecules with 44 Sc and 68 Ga for PET imaging

Non-invasive molecular-imaging technologies are playing a key role in drug discovery, development and delivery. Positron Emission Tomography (PET) is such a molecular imaging technology and a powerful tool for the observation of various deceases in vivo. However, it is limited by the availability of vectors with high selectivity to the target and radionuclides with a physical half-life which matches the biological half-life of the observed process. The 68Ge/68Ga radionuclide generator makes the PET-nuclide anywhere available without an on-site cyclotron. Besides the perfect availability 68Ga shows well suited nuclide properties for PET, but it has to be co-ordinated by a chelator to introduce it in a radiopharmaceuticals.rnHowever, the physical half-life of 68Ga (67.7 min) might limit the spectrum of clinical applications of 68Ga-labelled radiodiagnostics. Furthermore, 68Ga-labelled analogues of endoradiotherapeuticals of longer biological half-live such as 90Y- or 177Lu-labeled peptides and proteins cannot be used to determine individual radiation dosimetry directly. rnThus, radionuclide generator systems providing positron emitting daughters of extended physical half-life are of renewed interest. In this context, generator-derived positron emitters with longer physical half-life are needed, such as 72As (T½ = 26 h) from the 72Se/72As generator, or 44Sc (T½ = 3.97 h) from the 44Ti/44Sc generator.rnIn this thesis the implementation of radioactive gallium-68 and scandium-44 for molecular imaging and nuclear medical diagnosis, beginning with chemical separation and purification of 44Ti as a radionuclide mother, investigation of pilot generators with different elution mode, building a prototype generator, development and investigation of post-processing of the generator eluate, its concentration and further purification, the labeling chemistry under different conditions, in vitro and in vivo studies of labeled compounds and, finally, in vivo imaging experiments are described.

Microscopia elettronica di nanoparticelle mg-pd e mg-ti per stoccaggio di idrogeno.

L'utilizzo dell'idrogeno come vettore energetico �è negli ultimi anni uno dei temi in maggior rilievo riguardo la sostenibilit�à energetica, questo per via della sua abbondanza in natura, della sua elevata energia chimica per unità di massa, e della non tossicità dei prodotti della sua combustione. Tuttavia non si conosce ancora una maniera e�fficiente di immagazzinarlo per poterlo utilizzare per applicazioni mobili. In questo lavoro di tesi sono state cresciute, e analizzate mediante microscopia elettronica, nanoparticelle di magnesio decorate con metalli di transizione (Pd e Ti), che si collocano tra i candidati più promettenti per lo stoccaggio di idrogeno a stato solido.