Síntese e caracterização de TaC e óxido misto de tântalo e cobre nanoestruturados a partir do precursor oxálico de tântalo através de reações gás-sólido e sólido-sólido a baixa temperatura

The research and development of nanostructured materials have been growing significantly in the last years. These materials have properties that were significantly modified as compared to conventional materials due to the extremely small dimensions of the crystallites. The tantalum carbide (TaC) is an extremely hard material that has high hardness, high melting point, high chemical stability, good resistance to chemical attack and thermal shock and excellent resistance to oxidation and corrosion. The Compounds of Tantalum impregnated with copper also have excellent dielectric and magnetic properties. Therefore, this study aimed to obtain TaC and mixed tantalum oxide and nanostructured copper from the precursor of tris (oxalate) hydrate ammonium oxitantalato, through gas-solid reaction and solid-solid respectively at low temperature (1000 ° C) and short reaction time. The materials obtained were characterized by X-ray diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), Spectroscopy X-Ray Fluorescence (XRF), infrared spectroscopy (IR), thermogravimetric (TG), thermal analysis (DTA) and BET. Through the XRD analyses and the Reitiveld refinement of the TaC with S = 1.1584, we observed the formation of pure tantalum carbide and cubic structure with average crystallite size on the order of 12.5 nanometers. From the synthesis made of mixed oxide of tantalum and copper were formed two distinct phases: CuTa10O26 and Ta2O5, although the latter has been formed in lesser amounts

Correlação entre a infecção genital pelo vírus do papiloma humano, a resposta imune e os achados colpocitológicos em mulheres grávidas e não grávidas

The genital HPV infection is very common between men and women worldwide, affecting particularly young women, constituting a serious public health problem in less developed regions, favored by the poor living conditions of population. The cytology and colposcopy have notorious importance in the diagnosis of precursor lesions of cervical cancer and therefore its prevention. However, even with such diagnostic tools, the number of women who develop cervical cancer is still high. This study aims to assess the prevalence of genital tract infection by HPV in pregnant and nonpregnant women, evaluating the profile of the immune response presented by the women of these two groups in order to establish correlations among profile of immune response, presence of virus and occurrence of lesions of the uterine cervix. We analyzed specimens obtained from the cervix of 221 patients, 91 pregnant and 130 non-pregnant, aged 14-72 years. The women were subjected to colposcopic and cytologic evaluation detect possible changes in the cervix and then samples were collected in order to perform HPV detection by PCR and real-time PCR for detection of mRNA of pro-inflammatory and anti-inflammatory cytokines. In the present study, the overall prevalence of HPV genital infection was 28.1%; of which 31.9% were pregnant patients and 25.4% in non-pregnant women. Young women under 30 years and those with low educational level education showed a higher risk of HPV infection. Colposcopy showed better correlation with detection of HPV DNA by PCR, when compared to cytology. Generally, HPV infected patients, pregnant or not, exhibited reduced mRNA expression of both pro-inflammatory (IFN-γ, TNF-α) and anti-inflammatory (IL -10) cytokines, when compared to patients not infected by HPV. Nonpregnant patients infected presented increase mRNA expression of IL-17 in patients without injury, whereas those with lesion showed higher mRNA expression of TGF-β. Pregnant women without injury infected exhibited increased mRNA expression of TGF-β. There was no difference in HPV prevalence between pregnant and nonpregnant women. There was a reduction of pro-inflammatory cytokines, except IL-17, in all women infected by HPV. Moreover, we observed an increase of TGF-β in HPV-infected women who are pregnant or not. The results suggest that, in women in this study, HPV infection promoted changes in the profile of cytokines necessary for activation of effective immune response, possibly favoring viral persistence

Estudo das características magnéticas e absorvedoras das ferritas de nizn, niznmn, mnzn, nimg, nicuzn e nicuznmg obtidas via método do citrato precursor

Were synthesized systems Ni0,5Zn0,5Fe2O4, i0,2Zn0,5Mn0,3Fe2O4, Mn0,5Zn0,5Fe2O4, Ni0,5Mg0,5Fe2O4, Ni0,2Cu0,3Zn0,5Fe2O4 and Ni0,2Cu0,3Zn0,5Mg0,08Fe2O4, the precursors citrate method. The decomposition of the precursors was studied by thermogravimetric analysis and spectroscopy in the infrared region, the temperature of 350°C/3h. The evolution of the phases formed after calcinations at 350, 500, 900 and 1100ºC/3h was accompanied by X-ray diffraction using the Rietveld refinement to better identify the structures formed. The materials were also analyzed by scanning electron microscopy, magnetic measurements and analysis of the reflectivity of the material. The samples calcined at different temperatures showed an increase of crystallinity with increasing calcination temperature, verifying that for some compositions at temperatures above 500°C precipitates of second phase such as hematite and CuO. The compositions of manganese present in the structure diffusion processes slower due to the ionic radius of manganese is greater than for other ions substitutes, a fact that delays the stabilization of spinel structure and promotes the precipitation of second phase. The compositions presented with copper precipitation CuO phase at a temperature of 900 and 1100ºC/3h This occurs according to the literature because the concentration of copper in the structure is greater than 0.25 mol%. The magnetic measurements revealed features of a soft ferrimagnetic material, resulting in better magnetic properties for the NiZn ferrite and NiCuZnMg at high temperatures. The reflectivity measurements showed greater absorption of electromagnetic radiation in the microwave band for the samples calcined at 1100ºC/3h, which has higher crystallite size and consequently the formation of multi-domain, increasing the magnetization of the material. The results of absorption agreed with the magnetic measurements, indicating among the ferrites studied, those of NiZn and NiCuZnMg as better absorbing the incident radiation.

Obtenção e caracterização de filmes SnO2 depositados em vidro borosilicato por silk-screen modificado: SnCl2.2H2O como precursor

O presente trabalho tem como objetivo investigar as características de filmes de SnO2 depositados em substrato de vidro borosilicato por um processo de silk-screen modificado para obtenção de espessura fina compatível com a aplicação em células solares policristalinas de baixo custo. O filme de SnO2 é um dos mais apropriados para obtenção de vidro TCO (transparent conductive oxide) para uso em células solares devido a sua baixa resistividade elétrica e alta transmitância, sendo quimicamente inerte, mecanicamente duro e tem resistência a altas temperaturas, o que facilita então a calcinação das amostras entre 500º C a 550º C. Os filmes foram obtidos a partir de uma solução precursora básica, preparada pela dissolução de SnCl2.2H2O em Etanol (99,5 %). Foi realizado um planejamento fatorial 2(3-1) para analisar a influência dos parâmetros concentração da solução precursora (CETN), temperatura de calcinação (TC) e taxa de aquecimento (tX) na calcinação, sendo a concentração CETN o parâmetro que apresentou maior efeito sobre os parâmetros de respostas investigados: espessura do filme (ω), resistividade de superfície (ρ) e a transmitância relativa (θ). Foi possível obter com a metodologia utilizada, filmes com espessuras da ordem de 1 Nm com resistividade de superfície de 10 / e transmitância relativa entre 70 e 80 %.

Síntese e caracterização de TaC e óxido misto de tântalo e cobre nanoestruturados a partir do precursor oxálico de tântalo através de reações gás-sólido e sólido-sólido a baixa temperatura

The research and development of nanostructured materials have been growing significantly in the last years. These materials have properties that were significantly modified as compared to conventional materials due to the extremely small dimensions of the crystallites. The tantalum carbide (TaC) is an extremely hard material that has high hardness, high melting point, high chemical stability, good resistance to chemical attack and thermal shock and excellent resistance to oxidation and corrosion. The Compounds of Tantalum impregnated with copper also have excellent dielectric and magnetic properties. Therefore, this study aimed to obtain TaC and mixed tantalum oxide and nanostructured copper from the precursor of tris (oxalate) hydrate ammonium oxitantalato, through gas-solid reaction and solid-solid respectively at low temperature (1000 ° C) and short reaction time. The materials obtained were characterized by X-ray diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), Spectroscopy X-Ray Fluorescence (XRF), infrared spectroscopy (IR), thermogravimetric (TG), thermal analysis (DTA) and BET. Through the XRD analyses and the Reitiveld refinement of the TaC with S = 1.1584, we observed the formation of pure tantalum carbide and cubic structure with average crystallite size on the order of 12.5 nanometers. From the synthesis made of mixed oxide of tantalum and copper were formed two distinct phases: CuTa10O26 and Ta2O5, although the latter has been formed in lesser amounts