Nanometric Particle Size And Phase Controlled Synthesis And Characterization Of γ-fe2o3 Or (α + γ)-fe2o3 By A Modified Sol-gel Method

Fe2O3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel method. Maghemite particles as well as particles with admixture of maghemite and hematite were obtained and characterized by XRD, FTIR, UV-Vis photoacoustic and Mössbauer spectroscopy, TEM, and magnetic measurements. The size and hematite/maghemite ratio of the nanoparticles were controlled by changing the Fe:PVA (poly (vinyl alcohol)) monomeric unit ratio used in the medium reaction (1:6, 1:12, 1:18, and 1:24). The average size of the nanoparticles decreases, and the maghemite content increases with increasing PVA amount until 1:18 ratio. The maghemite and hematite nanoparticles showed cubic and hexagonal morphology, respectively. Direct band gap energy were 1.77 and 1.91 eV for A6 and A18 samples. Zero-field-cooling-field-cooling curves show that samples present superparamagnetic behavior. Maghemite-hematite phase transition and hematite Néel transition were observed near 700 K and 1015 K, respectively. Magnetization of the particles increases consistently with the increase in the amount of PVA used in the synthesis. Mössbauer spectra were adjusted with a hematite sextet and maghemite distribution for A6, A12, and A24 and with maghemite distribution for A18, in agreement with XRD results. © 2013 AIP Publishing LLC.11410Xu, P., Zeng, G.M., Huang, D.L., Feng, C.L., Hu, S., Zhao, M.H., Lai, C., Liu, Z.F., (2012) Sci. Total Environ., 424, pp. 1-10. , 10.1016/j.scitotenv.2012.02.023Rajabi, F., Karimi, N., Saidi, M.R., Primo, A., Varma, R.S., Luque, R., (2012) Adv. Synth. Catal., 354, pp. 1707-1711. , 10.1002/adsc.201100630Kitamuraa, H., Zhaob, L., Hangc, B.T., Okadab, S., Yamaki, J.-I., (2012) J. Power Sources, 208, pp. 391-396. , 10.1016/j.jpowsour.2012.02.051Figuerola, A., Di Corato, R., Manna, L., Pellegrino, T., (2010) Pharmacol. 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Studies of the thermal behavior of β-blockers antihypertensive drugs: labetalol and metoprolol

O comportamento térmico de dois fármacos anti-hipertensivos da classe dos β-bloqueadores, o cloridrato de labetalol e o tartarato de metoprolol, além da base livre do metoprolol foram investigados. Nos estudos envolvendo o cloridrato de labetalol, verificou-se que o fármaco funde em Tfus = 189,2 °C e logo em seguida se decompõe liberando água, ácido isociânico, o qual se decompõe em amônia e dióxido de carbono, e metilbenzeno, em suas etapas de perda de massa, respectivamente. O mecanismo proposto para a degradação desse fármaco foi corroborado tanto pelas técnicas termoanalíticas, quanto pela caracterização dos intermediários por GC-MS. Já os estudos do tartarato de metoprolol revelaram que este funde em Tfus = 121,7 °C e se decompõe em duas etapas de perda de massa, liberando na primeira delas seu contra íon, ácido tartárico, o qual se decompõe em água, dióxido e monóxido de carbono. Em seguida, durante a decomposição, o fármaco libera dimetileter, sofre uma dimerização, e depois se decompõe em isocianato de propila, dióxido de carbono, amônia e 1-etoxi-4-metillbenzeno. Esse mecanismo foi proposto com base nos resultados das técnicas termoanalíticas e na análise por HPLC-MS do intermediário coletado a 290 °C. Adicionalmente, foi feita a caracterização térmica da base do metoprolol. Os estudos indicaram que a forma comercial, Forma I, funde em Tfus = 51,1 °C e depois passa por uma recristalização, dando origem a um polimorfo, que funde em Tfus = 36,3 °C, posteriormente chamado de Forma II, que foi o primeiro polimorfo da base de metoprolol descrito na literatura. Além das técnicas termoanalíticas, os polimorfos foram caracterizados por difração de raios X de pó (XRPD) e espectroscopia na região do infravermelho (FTIR) que, em conjunto, indicaram que a relação entre as duas formas é monotrópica, sendo a Forma II a metaestável. Paralelamente, a estrutura cristalina da base foi determinada por difração de raios X de monocristal (XSRD).. Além disso, outras pesquisas sobre novas formas sólidas do metoprolol foram feitas, que envolveram a síntese de um novo sal utilizando a base e o ácido nicotínico. A estrutura cristalina do nicotinato de metoprolol foi resolvida e seu comportamento térmico foi estudado, revelando que o novo sal pode ser um potencial candidato a novas formulações farmacêuticas.The thermal behavior of two β-blocker antihypertensive drugs, labetalol hydrochloride and metoprolol tartrate, as well as the metoprolol free base, was investigated. In labetalol hydrochloride studies, it was found that the drug melts at Tfus = 189,2 °C and then it promptly decomposes releasing water and isocyanic acid, which decomposes in ammonia and carbon dioxide, and methylbenzene, in the subsequent steps of mass loss, respectively. The proposed mechanism for the degradation of labetalol hydrochloride was corroborated by both thermoanalytical techniques and the characterization of intermediates using GC-MS. Regarding of metoprolol tartrate, the studies revealed that it melts at Tfus = 121.7 °C and decomposes in two stages of mass loss, releasing tartaric acid in the first step, its counter ion, which decomposes in water and carbon monoxide and dioxide. During the decomposition, metoprolol releases dimethylether, makes a dimer, and then it decomposes in propyl isocyanate, carbon dioxide, ammonia and 1-ethoxy-4-methylbenzene. This mechanism was proposed based on the results of thermoanalytical techniques and HPLC-MS analysis of the intermediate collected at 290 °C. Additionally, the thermal characterization of the metoprolol base was performed. The studies indicated that the commercial form, Form I, melts at Tfus = 51,1 °C and then recrystallizes in a new polymorphic form, which melts at Tfus = 36,3 °C, named as Form II, which was the first polymorph described in the literature for the metoprolol base. In addition to thermoanalytical techniques, the polymorphs were characterized by powder X-ray diffraction (XRPD) and infrared spectroscopy (FTIR), which indicated that the relationship between the two forms is monotropic, with Form II being the metastable one. At the same time, the crystal structure of the base was determined by single crystal X-ray diffraction (XSRD). Besides that, an investigation of new solid forms of metoprolol has been performed, which involved the synthesis of a new salt using metoprolol and nicotinic acid. The crystal structure of metoprolol nicotinate was resolved and its thermal behavior was also studied, revealing that the new salt may be a potential candidate for new pharmaceutical formulations

Migrações internacionais e políticas públicas: análise da recepção aos venezuelanos à luz dos institutos do visto de residência e da acolhida humanitária = International migrations and public policies: the reception of Venezuelans in the light of residency visa and humanitarian welcoming institutes

- DOI: https://doi.org/10.30612/videre.v12i23.997

Novos direitos fundamentais no âmbito da União de Nações Sul-Americanas: análise das agendas de Brasil e Venezuela à luz do direito à paz = New fundamental rights within the scope of Union of South American Nations: analysis of the Brazil and Venezuela agendas in the light of the right to peace

- DOI: 10.5102/rdi.v15i2.506

Severe Dementia Predicts Weight Loss by the Time of Death

Background: Body mass index (BMI) in midlife is associated with dementia. However, the association between BMI and late-life obesity is controversial. Few studies have investigated the association between BMI and cognitive performance near the time of death using data from autopsy examination. We aimed to investigate the association between BMI and dementia in deceased individuals who underwent a full-body autopsy examination. Methods: Weight and height were measured before the autopsy exam. Cognitive function before death was investigated using the Clinical Dementia Rating (CDR) scale. The cross-sectional association between BMI and dementia was investigated using linear regression models adjusted for sociodemographic and clinical variables. Results: We included 1,090 individuals (mean age 69.5 ± 13.5 years old, 46% women). Most participants (56%) had a normal BMI (18.5-24.9 kg/m2), and the prevalence of dementia was 16%. Twenty-four percent of the sample had cancer, including 76 cases diagnosed only by the autopsy examination. Moderate and severe dementia were associated with lower BMI compared with participants with normal cognition in fully adjusted models (moderate: β = -1.92, 95% CI = -3.77 to -0.06, p = 0.042; severe: β = -2.91, 95% CI = -3.97 to -1.86, p < 0.001). Conclusion: BMI was associated with moderate and severe dementia in late life, but we did not find associations of BMI with less advanced dementia stages

Nanometric particle size and phase controlled synthesis and characterization of gamma-Fe2O3 or (alpha plus gamma)-Fe2O3 by a modified sol-gel method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fe2O3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel method. Maghemite particles as well as particles with admixture of maghemite and hematite were obtained and characterized by XRD, FTIR, UV-Vis photoacoustic and Mossbauer spectroscopy, TEM, and magnetic measurements. The size and hematite/maghemite ratio of the nanoparticles were controlled by changing the Fe:PVA (poly (vinyl alcohol)) monomeric unit ratio used in the medium reaction (1:6, 1:12, 1:18, and 1:24). The average size of the nanoparticles decreases, and the maghemite content increases with increasing PVA amount until 1:18 ratio. The maghemite and hematite nanoparticles showed cubic and hexagonal morphology, respectively. Direct band gap energy were 1.77 and 1.91 eV for A6 and A18 samples. Zero-field-cooling-field-cooling curves show that samples present superparamagnetic behavior. Maghemite-hematite phase transition and hematite Neel transition were observed near 700K and 1015 K, respectively. Magnetization of the particles increases consistently with the increase in the amount of PVA used in the synthesis. Mossbauer spectra were adjusted with a hematite sextet and maghemite distribution for A6, A12, and A24 and with maghemite distribution for A18, in agreement with XRD results. (C) 2013 AIP Publishing LLC.11410Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)MCI [Spain-PHB 2008-0044-PC]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES [184-09]MCI [Spain-PHB 2008-0044-PC