963 resultados para irreversible


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The dehydration, thermal decomposition and transition phase stage of Zn(II)-diclofenac compoundwere studied by simultaneous TG-DTA and DSC techniques. The TG and DSC curves of this compoundwere obtained with the mass of sample of 2 and 5 mg. Additionally, DSC curves were carried out inopened and closed a-alumina pans under static and nitrogen atmosphere. The DTA and DSC curves showthat this compound possesses exothermic transition phase between 170-180 ºC, which it is irreversible(monotropic reaction). The kinetics study of this transition phase stage was evaluated by DSC undernon-isothermal conditions. The obtained data were evaluated with the isoconversional method, where thevalues of activation energy (Ea/kJmol-1) was plotted in function of the conversion degree (a). The resultsshow that due to mass sample, different activation energies were obtained. From these curves a tendencycan be seen where the plots maintain the same profile for closed lids and almost run parallel to each other.

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The Polymeric Precursor Method has proved suitable for synthesizing reactive powders using low temperatures of calcination, especially when compared with conventional methods. However, during the thermal decomposition of the polymeric precursor the combustion event can be releases an additional heat that raises the temperature of the sample in several tens of degrees Celsius above the set temperature of the oven. This event may be detrimental to some material types, such as the titanium dioxide semiconductor. This ceramic material has a phase transition at around 600 ° C, which involves the irreversible structural rearrangement, characterized by the phase transition from anatase to rutile TiO2 phase. The control of the calcination step then becomes very important because the efficiency of the photocatalyst is dependent on the amount of anatase phase in the material. Furthermore, use of dopant in the material aims to improve various properties, such as increasing the absorption of radiation and in the time of the excited state, shifting of the absorption edge to the visible region, and increasing of the thermal stability of anatase. In this work, samples of titanium dioxide were synthesized by the Polymeric Precursor Method in order to investigate the effect of Fe (III) doping on the calcination stages. Thermal analysis has demonstrated that the Fe (III) insertion at 1 mol% anticipates the organic decomposition, reducing the combustion event in the final calcination. Furthermore, FTIR-PAS, XRD and SEM results showed that organic matter amount was reduced in the Fe (III)-doped TiO2 sample, which reduced the rutile phase amount and increased the reactivity and crystallinity of the powder samples.

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A novel nanostructured composite, azide copper octa (3-aminopropyl)octasilsesquioxane (ASCA) was incorporated into a graphite paste electrode and the electrochemical studies were conducted with cyclic voltammetry. The cyclic voltammogram of the modified graphite paste electrode with ASCA (GPE-ASCA), showed one redox couple with formal potential (E  ) = 0.30 V and an irreversible process at 1.1 V (vs Ag/AgCl; NaCl 1.0 mol L-1 ; v = 20 mV s-1 ). The redox couple with (E  ) = 0.30V presents an electrocatalytic response for determination of ascorbic acid. The modified electrode gives a linear range from 1.010-4 – 1.010-3 mol L-1 (r = 0.998) for the determination of ascorbic acid with detection limit of 6.910-5 mol L-1 and standard deviation of 2.3% for n = 3 . The amperometric sensitivity was 122.1 mA/mol L-1 for ascorbic acid. The application this electrode was tested and ascorbic acid in three commercial pharmaceutical product (Cebion, Cewin and Redoxon) have been determined.

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The influence of both thermal treatment and laser irradiation on the structural and optical properties of films in the Sb 2 O 3 –Sb 2 S 3 system was investigated. The films were prepared by RF-sputtering using glass compositions as raw materials. Irreversible photodarkening effect was observed after exposure the films to a 458nm solid state laser. It is shown, for the first time, the use of holographic technique to measure “in situ”, simultaneously and independently, the phase and amplitude modulations in glassy films. The films were also photo-crystallized and analysed “in situ” using a laser coupled to a micro-Raman equipment. Results showed that Sb 2 S 3 crystalline phase was obtained after irradiation. The effect of thermal annealing on the structure of the films was carried out. Different from the result obtained by irradiation, thermal annealing induces the crystallization of the Sb 2 O 3 phase. Photo and thermal induced effects on films were studied using UV–Vis and Raman spectroscopy, atomic force microscopy (AFM), thermal analysis (DSC), X-ray diffraction, scanning electron microscopy (MEV) and energy-dispersive X-ray spectroscopy (EDX).

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Microbiologia Agropecuária - FCAV

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Congenital toxoplasmosis is a serious public health case, for it causes irreversible damage to the embryo/fetus, which may cause its death. The identification and the care to pregnant women with suspect acute toxoplasmosis (IgM+) is performed in prenatal monitoring. This study aimed to measure the incidence and know the profile of positive pregnant women for toxoplasmosis in a Basic Health Unit (BHU) in Matão - SP, between the years 2011 to 2013. This is a retrospective descriptive study, from the medical records of pregnant women attended. The project was approved by the Municipal Departament of Health and BHU was chosen along the Municipal Epidemiological Surveillance. From 2011 to 2013, 189 women began prenatal care in the unit, an annual median of 71(±26.91), of which 17 (8.99%) were positive for the serological test indicative of acute phase (IgM+). The distribution over the trial period was: four cases in 2011, twelve cases in 2012 and one in 2013. Pregnant women IgM positive for toxoplasmosis attend by BHU were: age 24(±5.47) years; color: equally distributed among white, black and brown; as the number of pregnancies: multiparous (2±0.97), most of them with a cesarean delivery as obstetric history and possessed no other risk factors associated with pregnancy (94.12%); gave entrance at BHU with 13.65(±7.35) weeks of gestation and had a median of 5(±2.36) consultation on their prenatal care. The examination for toxoplasmosis was requested as recommended by the Health Ministry (HM) and the medication prescribed was Roxamicina® - spiramycin, as soon as the test results (IgM+) arrived. Of the 17 pregnant women, only 10 completed the pre-natal at BHU - attendance at the postpartum consult (58.8%). Of these, the deliveries were vaginal (55.55%), made preterm with 36.5 weeks of gestation at the Municipal Hospital. The babies were born alive (100%) with the weight of 2.68(±0.77) Kg and required special care hospital scope. From the ...

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The present study aims at evaluating dimensional alteration of stone casts made from impressions with a standard irreversible hydrocolloid and an antimicrobial one. For this, an alginate without disinfectant (Type II Jeltrate) and other containing chlorhexidine (Type II Avagel) were used, which rose by the same regime of treatment: without disinfection; immersion; and spraying. A 1% sodium hypochlorite solution was used for 10 minutes. To obtain the impressions, a perforated impression tray was made from a standard metal model. After molding, the molds were washed in running water for 30 seconds to simulate removal of saliva. Then, with the exception of the control group, these molds were subjected to disinfection treatment. After 10 minutes they were washed again. 60 samples poured with type V special gypsum (Durone) were obtained, that were measured 3 times in a stereomicroscope (SZX12, Olympus) to record the average of dimensional alterations. The disinfection treatment did not bring significant changes in the models obtained from both alginate tested (standard p = 0.7102; with chlorhexidine p = 0.5832). The results showed a statistically significant and additional advantage of the traditional alginate on alginate with chlorhexidine, with respect to dimensional alteration (p < 0.05).

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The electrochemical behaviour of N-R-4-cyanopyridinium (4-rcp) (R = methyl, decyl, dodecyl, or benzyl) coordinated to pentaammineruthenium(II) in CF3COOH-CF3COONa (μ = 0.1 M, pH 3) aqueous medium was studied by means of cyclic voltammetry and constant potential electrolysis. The electrochemical oxidation of the metallic centre (Ep ca 0.51 V/SCE) can be described as a reversible monoelectronic charge-transfer followed by an irreversible chemical reaction, which is the hydrolysis of N-R-4-cyanopyridiniumpentaammineruthenium(III) (A) to N-R-4-carboxamidepyridiniumruthenium (III) (B) with the kf1 values depending on the type of alkyl group. The E 1 2 values are not significantly influenced by the nature of the alkyl group. At more negative potential (ca -0.5 V/SCE), B undergoes an electrochemical reduction followed by an aquation reaction to produce aquopentaammineruthenium(II) and free N-R-4-carboxamidepyridinium. The amide was identified by comparison of its cyclic voltammogram and UV-vis spectrum with that of a sample prepared by chemical reaction. The results were also discussed by comparison with other systems, and show that nitrile-amide conversion catalysed by pentaammineruthenium(II) complexes is possible. © 1994.

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Pós-graduação em Saúde Coletiva - FMB

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The choice of surgical approach to diseases that affect the pre-auricular region has been subject of much discussion in the literature. Access pre-hearing, have been used with high compliance rate of success, and during the history of surgery, several modifications were made in this approach with the goal of reducing the irreversible consequences especially regarding common in condylar fractures as paralysis and facial scars. The views range from the indication of surgical treatment for all fractures, until the conviction that no fracture of the bone segment should be surgically treated. Therefore, this study is of relevance, since offers surgeons warn about the care on the anatomical structures involved in these surgical approaches and describe, seeking a comparison between them, the advantages of them by means of a literature review covering from the extensive bouts of Bellinger (1940) and Al-Kayat (1979) that provide a broad view of the surgical field to access modified and increasingly smaller as the endaural (2001) which not only allows a satisfactory field of aesthetics as maintenance the patient without any signs of scarring.

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The progressive condylar resorption is a irreversible complication that can result in malocclusion and facial deformity that can happen especially in postoperative orthognathic surgery of mandibular advancement or combined surgery. Predominantly affect young women, bearers of malocclusions of skeletal class II and with incidence of temporomandibular disorders prior to surgical treatment. Its exact etiology and pathogenesis remain unclear. The purpose of this article is to make a literature review of the last 10 years on the progressive condylar resorption. For this, we used the Medline database for articles in the English language. Then, 13 articles were found, evaluated and compared on predisposing factors, etiology, diagnosis and clinical management.

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The concepts of buccal health promotion and the increase of life expectancy have contributed for the highest maintenance of dental elements. Thus, with the new alimentary and behavioral habits the irreversible loss of dental hard tissue of non-carious origin has increased substantially, being divided in attrition, erosion and abrasion. The dental erosion is a chronic pathology defined as the superficial loss of dental hard tissue as a result of a chemical process not involving bacteria caused by acid that could be intrinsic, extrinsic or unknown etiology, causing irreversible loss of mineral tissue and dentinal hypersensitivity. The aim of this paper is to present a review of literature on the main factors that can cause the injuries of erosion, including the different aspects related to its etiology, classification, diagnosis, prevention and treatment.

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Paracoccidioidomycosis and aspergillosis are, respectively, mycosis caused by Paracoccidioides brasiliensis and Aspergillus fumigatus fungi, which, most frequently, attack the lungs and later spread to other body regions. The association between both mycosis is rare in patients that do not present immunosuppression. A 49-year-old man presented with oral lesion, besides lesions on palatum, retromolar and oropharyngeal regions. Histopathological and microbiological exams confirmed the diagnosis of paracoccidioidomycosis associated to aspergillosis. Historically, fungi have been considered as the cause of relatively important infections, but, in the last years, a significant increase of diseases caused by fungi is evidenced. The recognition of the etiological agent in culture is important for the suitable treatment, once these fungi can cause irreversible damages or even death. The purpose of this study was to demonstrate, through the case of a patient who presented both mycosis associated, the need of complementary exams for the diagnosis of oral diseases, when routine laboratorial exams indicate the presence of another disease associated.