Comparative study of the lipid profiles of oils from kernels of peanut, babassu, coconut, castor and grape by GC-FID and Raman spectroscopy

The characterization of the lipid profiles of oils extracted from the kernel of seeds and nuts of peanut (Arachis hypogaea), babassu (Attalea speciosa), coconut (Cocos nucifera), castor (Ricinus communis) and grape (Vitis vinifera) was performed by using Raman spectroscopy and gas chromatography with flame ionization detector (GC-FID). Chromatographic analyses showed that coconut and babassu oils are composed essentially by saturated fatty acids (SFA), whereas the others are composed mainly by unsaturated fatty acids (UFA). The comparison of commercial and homemade castor oils showed the former have a lower level of ricinoleic acid at ca. 58%. Spectroscopic analyses of three distinct castor oils showed their profiles could be differentiated by marker features ascribed to carbonyl modes which were correlated with storage time. The comparison between the Raman spectra of standard samples of fatty acids with the samples of oils allowed the assignment of the spectroscopic features and the characterization of marker bands for the degree of unsaturation.

Surface-enhanced Raman spectroscopy studies of organophosphorous model molecules and pesticides

This work reports the analytical application of surface-enhanced Raman spectroscopy (SERS) in the trace analysis of organophosphorous pesticides (trichlorfon and glyphosate) and model organophosphorous compounds (dimethyl methylphosphonate and o-ethyl methylphosphonothioate) bearing different functional groups. SERS measurements were carried out using Ag nanocubes with an edge square dimension of ca. 100 nm as substrates. Density functional theory (DFT) with the B3LYP functional was used for the optimization of ground state geometries and simulation of Raman spectra of the organophosphorous compounds and their silver complexes. Adsorption geometries and marker bands were identified for each of the investigated compound. Results indicate the usefulness of SERS methodology for the sensitive analyses of organophosphorous compounds through the use of vibrational spectroscopy.FAPESPFAPESPCNPqCNPqCAPESCAPE

Synergism in the antibacterial action of ternary mixtures involving silver nanoparticles, chitosan and antibiotics

The investigations of the antibacterial actions, observed in ternary associations involving silver nanoparticles (AgNPs), chitosan and the antibiotics azithromycin (AZ), levofloxacin (LE) or tetracycline (TE), against Gram-negative and Gram-positive bacterial strains, were performed by in vitro antimicrobial susceptibility testing and checkerboard assays. The pH impact in the culture medium was carefully discarded, but preserving the best conditions for solubilizing chitosan. The synergistic antibacterial effects were observed in the most combinations of AgNPs, chitosan and antibiotic, leading to a reduction from 37 to 97% in the minimum inhibitory concentration of the drugs. The mechanisms for the enhanced antimicrobial effects were proposed based on the investigations of the adsorptions of the drugs on the silver surfaces through surface-enhanced Raman scattering (SERS) spectroscopy.

O comportamento do consumidor de vinho no mercado português

A presente investigação resultou da necessidade de perceber as razões que motivam e que eventualmente poderão condicionar a frequência de consumo de vinho em Portugal. Deste modo, o principal objetivo deste trabalho é compreender as motivações de compra e consumo, dependendo da situação de uso e de caraterísticas pessoais. A literatura existente sobre as motivações de consumo de vinho salienta a existência de efeitos diretos sobre as motivações do género do comprador e da ocasião de consumo. Este estudo introduz uma formulação alternativa destes efeitos, considerando-os indiretos, i.e. completamente mediados pelo conhecimento subjetivo do comprador e pelas emoções que ele associa ao respetivo consumo. Foram desenvolvidos dois modelos, um para explicar as motivações, outro a frequência de consumo, os quais foram posteriormente validados numa amostra de 523 compradores entrevistados no momento da compra em grandes superfícies retalhistas da Grande Lisboa e do Grande Porto. Os resultados apresentados no primeiro modelo apontam para a rejeição dos efeitos diretos, sendo o conhecimento subjetivo o mediador mais importante. Sugere-se que a autoconfiança e a eficácia na decisão, que aparecem associadas ao conhecimento subjetivo, justifiquem que os homens se sintam mais motivados para o consumo. Este efeito positivo do conhecimento na motivação é ainda mais importante nas ocasiões regulares. No segundo modelo, verificou-se que a frequência de consumo é explicada predominantemente pela motivação por gratificação sensorial e, também, pela ocasião de consumo no contexto de refeição normal (efetuada no dia-a-dia). O conhecimento subjetivo revelou-se também como elemento fundamental no comportamento do consumidor, quer pela sua influência sobre as motivações, quer pela sua influência sobre a frequência de consumo. As conclusões retiradas desta investigação salientam a importância do conhecimento subjetivo no consumo de vinho. Realçam também que os efeitos de fatores como o género e a ocasião sobre as motivações para consumir vinho, reportados na literatura, poderão dever-se a mediadores de ordem psicográfica, como o conhecimento subjetivo. Esta conclusão tem implicações no marketing de vinhos para compradores regulares, nomeadamente pelo reconhecimento da necessidade de reforçar a perceção de confiança e de eficácia de decisão que costumam ser associadas aos elevados níveis de conhecimento percebido numa categoria de produto

A proposal for the adsorption of anastrozole anticancer drug on gold nanoparticle surfaces

Anastrozole is a well-known anticancer drug used in aromatase-dependent cancer chemotherapy as a nonsteroidal aromatase inhibitor. Investigations involving the adsorption of anastrozole on gold surfaces are on demand, because gold nanoparticles (AuNPs) have been used as nanocarriers of drugs, and such a compound can be used against aromatase-expressing neoplastic cells. In this work, surface-enhanced Raman scattering (SERS) spectroscopy was used to investigate the interaction between anastrozole and the surfaces of AuNPs. Density functional theory (DFT) calculations were used to simulate the molecular interactions with gold atom through two possible ways, triazole or nitrile moieties. Experimental results, supported by DFT calculations to assign main vibrational modes, indicate that the nitrile groups are the most preferred anchorage moieties for the adsorption