Use of dialkyldithiocarbamato complexes of bismuth(III) for the preparation of nano- and microsized Bi2S3 particles and the X-ray crystal structures of [Bi{S2CN(CH3)(C6H13)}(3)] and [Bi{S2CN(CH3)(C6H13)}(3)(C12H8N2)]

A range of bismuth(III) dithiocarbamato complexes were prepared and characterized. The X-ray crystal structures of the compounds [Bi{S2CN(CH3)(C6H13)}3] (1) and [Bi{S2CN(CH3)- (C6H13)}3(C12H8N2)] (2) are reported. The preparation of Bi2S3 particulates using a wet chemical method and involving the thermalysis of Bi(III) dialkyldithiocarbamato complexes is described. The influence of several experimental parameters on the optical and morphological properties of the Bi2S3 powders was investigated. Nanosized Bi2S3 colloids were obtained having long-term stability and showing a blue shift on the optical band edge; the presence of particles exhibiting quantum size effects is discussed. Morphological welldefined Bi2S3 particles were obtained in which the fiber-type morphology is prevalent.FCT - POCTI/1999/CTM/ 3545

Carbamazepine polymorphism: a re-visitation using Raman imaging

Raman imaging methods have appeared in the last years as a powerful approach to monitoring the quality of pharmaceutical compounds. Because polymorphism occurs in many crystalline pharmaceutical compounds, it is essential to monitor polymorphic transformations induced by different external stimulus, such as temperature changes, to which those compounds may be submitted. Raman imaging with k-means cluster analysis (CA) is used here as an essential technique to investigate structural and chemical transformations occurring in carbamazepine p-monoclinic (CBZ III) into carbamazepine triclinic (CBZ I) when submitted to temperatures near the melting point of CBZ III (178 °C) and CBZ I (193 °C). CBZ III commercial powder and laboratorial prepared CBZ I were analyzed by differential scanning calorimetry, powder X-ray diffraction and Raman spectroscopy with variable temperature. After thermal treatment, the resultant CBZ powder was evaluated by Raman imaging, in which all imaging data was analyzed using CA. Raman imaging allowed the identification of different polymorphs of CBZ (CBZ III and CBZ I) and iminostilbene (IMS), a degradation product of CBZ, in the treated samples, depending on the heating treatment method.publishe

Unmixing of Magnetic Hysteresis Loops Through a Modified Gamma‐Cauchy Exponential Model

Abstract Quantifying the contributions of distinct mineral populations in bulk magnetic experiments greatly enhances the analysis of environmental and rock magnetism studies. Here, we develop a new method of parametric unmixing of susceptibility components in hysteresis loops. Our approach is based on a modified Gamma‐Cauchy exponential model that accounts for variable skewness and kurtosis. The robustness of the model is tested with synthetic curves that examine the effects of noise, sampling, and proximity (similar coercivities) of susceptibility components. We provide a Python‐based script, the Hist‐unmix, which allows the user to adjust a forward model of up to three ferromagnetic components as well as a dia/paramagnetic contribution. Optimization of all the parameters is achieved through least squares fitting (Levenberg‐Marquardt method), with uncertainties of each inverted parameter calculated through a Monte Carlo error propagation approach. For each ferromagnetic component, it is possible to estimate the saturation magnetization (Ms), saturation remanent magnetization (Mrs) and the mean coercivity (Bc). Finally, Hist‐unmix was applied to a set of weakly magnetic carbonate rocks from Brazil, which typically show distorted hysteresis loops (wasp‐waisted and potbellied). For these samples, we resolved two components with distinct coercivities. These results are corroborated by previous experimental data, showing that the lower branch of magnetic hysteresis can be modeled by the presented approach and might offer important mineralogical information for rock magnetic and paleomagnetic studies

Raman imaging studies on the stability of Paracetamol tablets under different storage conditions

The applicability of Raman imaging for pharmaceutics production ranges from the characterization of pharmaceutical formulations, kinetic processes in drug delivery to the rapid detection and identification of counterfeit drugs/contaminants. Acetaminophen (Paracetamol, APAP) is an analgesic and antipyretic drug and one of the most consumed medicines worldwide. On the other hand, the compound 4-aminophenol (4-AP) is a hydrolytic product of APAP with nephrotoxicity and teratogenic effects. In this work, we have explored for the first time Raman imaging methods to characterize the main components of commercial APAP tablets (APAP-tablets) and to inquire about the potential of this optical technique to identify 4-AP in APAP tablets, which have been previously spiked with such contaminant. The laboratorial treated APAP-tablet samples were subjected to different temperature, humidity and sunlight exposure conditions, mimicking storage conditions, and then the Raman spectra and images were collected to monitor changes that might occur in those conditions. Although the lower limit of detection of 4-AP in APAP-tablets is above the minimum levels established by Pharmacopoeias (0.005 %), this research demonstrates that Raman imaging still allows the detection of small amounts of the contaminant, thus opening perspectives for exploring this technique for characterizing APAP products.publishe

Dor: mecanismos envolvidos na sua transmissão e recursos terapêuticos aplicados à sua inibição

A dor é uma experiência desagradável, subjetiva, única e individual, possuindo aspectos sensoriais, afetivos, auto-nômicos e comportamentais. A sensação de dor é fundamental para a sobrevivência, sendo obrigatória a sua avaliação e a intervenção adequada. A dor pode ser classificada de várias formas, quanto à origem (química, neurogênica e mecânica), à natureza (nociceptiva, neuropática e complexa ou mista) e ordem da manifestação (aguda ou crônica). Devido à variação no limiar de dor entre espécies e até mesmo entre indivíduos da mesma espécie, tornou-se importante a mensuração da dor, que é realizada através de escalas unidimensionais ou multidimensionais. A dor tem inicio com a estimulação dos nociceptores que, através das fibras nervosas mielinizadas (tipo A?) ou amielinizadas (tipo C), transferem esse estimulo ao sistema nervoso central, onde ocorre à consciência da dor e a reposta do organismo a esse estímulo. As principais substâncias responsáveis pela sensibilização dos nociceptores são acetilcolina, prostaglandinas, histamina, serotonina, bradicinina, substância P, tromboxana, dentre outras. Vários fármacos podem ser utilizados no bloqueio terapêutico da dor, dentre eles pode citar os anestésicos gerais, anestésicos locais, analgésicos opióides, agonistas ?-2 adrenérgicos, anti-inflamatórios não esteroidais, bloqueadores adrenérgicos, antidepressivos, antagonistas de NMDA, benzodiazepínicos, fenotiazínicos, relaxantes musculares e nutracêuticos. Outras condutas não farmacológicas também podem ser utilizadas, como os métodos de estimulação elétrica e a acupuntura

Controle de doenças do maracujazeiro através do uso de produtos alternativos.

Publicado também em: Fitopatologia Brasileira, v. 30, p. S59, ago. 2005. Suplemento. Resumos do XXXVIII Congresso Brasileiro de Fitopatologia

Gold loaded textile fibres as substrates for SERS detection

Spectroscopic methods based on surface-enhanced Raman scattering (SERS) are among the analytical tools most exploited in recent years for the detection of vestigial amounts of compounds with environmental and health relevance. In the last decades, SERS methods have been largely improved with the unprecedented progress in instrumentation and materials development in the scope of nanoscale science. The current developments in Raman instruments, in particular for Raman imaging, brought a new look on composites and its applications. The use of confocal microscopes allows high resolution Raman mapping with short measurement times, creating strongly improved Raman images in two and three dimensions. In this manuscript, we will present an overview of our own research on the development of malleable and easy-handled SERS substrates based on textile fibres for analytical detection. The strategies employed for the coating of the textile fibres with gold nanoparticles (NPs) will be described in detail. A final section will focus on the combination of Raman imaging and SERS for the development of substrates based on textile fibres and their application on the detection of water pollutants and biomolecules. A case study on the development of cotton swab fibres coated with Au NPs for SERS detection of L-lactate will be illustrated in more detail.publishe

Does it still hold?

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