999 resultados para Calorimetria exploratória diferencial


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In this paper, the technique of differential pulse voltammetry (DPV) has been studied for monitoring the concentration of oxalic acid (OA) during their electrochemical oxidation (EO) in acidic medium using platinum anode supported on titanium (Ti / Pt). The DPV was standardized and optimized using a glassy carbon electrode modified with cysteine. The modification with cysteine was developed electrochemically, forming a polymeric film on the surface of the glassy carbon electrode. The formation of the polymer film was confirmed by analysis of scanning electron microscope and atomic force microscope, confirming the modification of the electrode. The electrochemical degradation was developed using different current densities 10, 20 30 and 40 mA cm -2 electrode with Ti / Pt observing the degradation of oxalic acid, and monitored using the method of KMnO4 titration. However, the analyzes with DPV showed the same behavior elimination of oxalic acid titration. Compared with the titration method classical observed and DPV could be a good fit, confidence limits of detection and confirming the applicability of the technique electroanalytical for monitoring the degradation of oxalic acid

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In this work a study was done using electrochemical cyclic voltammetry and differential pulse voltammetry for isoniazida (INH), ethambutol (EMB), rifampicina (RIF) and pyrazinamide (PZA) using the electrode boron-doped diamond (BDD) as working electrode. It also verified the applicability of the technique of differential pulse voltammetry in the quantification of the active compounds used in the treatment of tuberculosis, subsequently applying in samples of pharmaceutical formulation. Among the four active compounds studied, isoniazid showed the best results for the detection and quantification using differential pulse voltammetry. At pH 4 and pH 8, for the calibration curves to INH showed good linearity, with quantification limits of 6.15 mmol L-1 (0,844 ppm) and 4.08 mmol L-1 (0.560 ppm) for the respective pH. The proposed method can be used to determine drug isoniazid, for recovery values were obtained in approximately 100%

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The development of more selective and sensitive analytical methods is of great importance in different areas of knowledge, covering, for example, food, biotechnological, environmental and pharmaceutical sectors. The study aimed to employ the technique electroanalytical differential pulse voltammetry (DPV) as an innovative and promising alternative for identification and quantification of organic compounds. The organic compounds were investigated in this study oxalic acid (OA) and folic acid (FA). The electrochemical oxidation of oxalic acid has been extensively studied as a model reaction in the boundary between the organic and inorganic electrochemistry. Since the AF, an essential vitamin for cell multiplication in all tissues, which is essential for DNA synthesis. The AF has been investigated using analytical techniques, liquid chromatography and molecular absorption spectrophotometry. The results obtained during the experimental procedure indicated that the process of electrochemical oxidation of oxalic acid is strongly dependent on the nature of the anode material and the oxidation mechanism, which affects their detection. Efficient removal was observed in Ti/PbO2 anodes, graphite, BDD and Pt 90, 85, 80 and 78% respectively. It was also shown that the DPV employing glassy carbon electrode offers a fast, simple, reliable and economical way to determine the AO during the process of electrochemical oxidation. Furthermore, electroanalytical methods are more expensive than commonly used chromatographic analysis and other instrumental methods involving toxic reagents and higher cost. Compared with the classical method of titration and DPV could be a good fit, confidence intervals and detection limits confirming the applicability of electroanalytical technique for monitoring the degradation of oxalic acid. For the study of AF was investigated the electrocatalytic activity of the carbon paste electrode for identification and quantification in pharmaceutical formulations by applying the DPV. The results obtained during the experimental procedure showed an irreversible oxidation peak at 9.1 V characteristic of FA. The carbon paste sensor showed low detection limit of 5.683×10−8 mol L-1 reducing matrix effects. The spectrophotometric analysis showed lower concentrations of HF compared with those obtained by HPLC and DPV. The levels of AF were obtained according to the methodology proposed by the Brazilian Pharmacopoeia. The electroanalytical method (DPV) proposed is cheaper than GC analysis commonly used by the pharmaceutical industry. The results demonstrated the potential of these electroanalytical techniques for future applications in environmental, chemical and biological sensors

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The study aims to analyze the perception of managers on intangible assets as strategic and competitive resources in small hotels in Natal/RN, through the theory of the Resource Based View (RBV). This is a qualitative study of exploratory and descriptive, conducted with managers of the means of hosting small the capital of Rio Grande do Norte through semi-structured interviews, which was applied later, the technique content analysis based on the results of the information obtained in the interviews. Thus, research has shown that managers of small hotels visited (A, B, C) are not sufficient and satisfactory knowledge to set as their unique intangible assets of the company and makes use of them, on an occasional basis, without understanding or in essence understand its true value as a resource that can be used strategically for sustainable competitive advantage in the hotel market in Natal/RN. This means that managers do not know how to create new attributes and use them strategically. And they need to expand their partnerships with stakeholders. Given the importance of the subject of the present research, the information achieved by this analysis may contribute to the provision of information to establish a current situation with regard to the attributed to the knowledge and use of resources (intangible assets) importance as a strategic source and competitive for the internal management of the company by managers and thus, enabling a differential and greater economic profit over time in this segment

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Obsessive-compulsive disorder (OCD) has clinical features that overlap in various degrees with many other mental disorders. As a result, the differential diagnosis sometimes can be difficult. This review briefly summarizes the phenomenologic similarities and differences between OCD and the following disorders: depression, phobias, hypochondriasis and body dysmorphic disorder, Tourette syndrome and tic disorder, obsessive-compulsive personality disorder, impulse control and eating disorders, generalized anxiety, panic and post-traumatic stress disorders, and delusional and schizophrenic disorders. The accurate diagnosis is essential for adequate treatment planning and management.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Social phobia is a common mental disorder that can cause considerable distress and impairment in functioning and quality of life but it is still an underdiagnosed and undertreated disorder. The differential diagnosis is not always simple. because its clinical features overlap with many other mental and non-mental disorders characterized by social avoidance. The aim of this study was to review the literature and discuss the differential diagnosis of social phobia with the following conditions. normal social anxiety (shyness), depressive disorders, alcoholism, body dysmorphic disorder, panic disorder and agoraphobia, simple phobias, generalized anxiety disorder, obsessive-compulsive disorder, post-traumatic stress disorder, delusional disorders and avoidant and schizoid personality disorders. A Medline and Lilacs search was conducted between 1990 and 2002, using the key words social phobia, social anxiety disorder, diagnosis and defferential diagnosis. The accurate diagnosis is very important for the appropriate treatment approach.

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