Trends in properties of para-substituted 3-(phenylhydrazo)pentane-2,4-diones

Trends between the Hammett's sigma(p) and related normal sigma(n)(p), inductive sigma(I), resonance sigma(R), negative sigma(-)(p) and positive sigma(+)(p) polar conjugation and Taft's sigma(o)(p) substituent constants and the N-H center dot center dot center dot O distance, delta(N-H) NMR chemical shift, oxidation potential (E-p/2(ox), measured in this study by cyclic voltammetry (CV)) and thermodynamic parameters (pK, Delta G(0), Delta H-0 and Delta S-0) of the dissociation process of unsubstituted 3-(phenylhydrazo)pentane-2,4-dione (HL1) and its para-substituted chloro (HL2), carboxy (HL3), fluoro (HL4) and nitro (HL5) derivatives were recognized. The best fits were found for sigma(p) and/or sigma(-)(p) in the cases of d(N center dot center dot center dot O), delta(N-H) and E-p/2(ox), showing the importance of resonance and conjugation effects in such properties, whereas for the above thermodynamic properties the inductive effects (sigma(I)) are dominant. HL2 exists in the hydrazo form in DMSO solution and in the solid state and contains an intramolecular H-bond with the N center dot center dot center dot O distance of 2.588(3)angstrom. It was also established that the dissociation process of HL1-5 is non-spontaneous, endothermic and entropically unfavourable, and that the increase in the inductive effect (sigma(I)) of para-substitutents (-H < -Cl < -COOH < -F < -NO2) leads to the corresponding growth of the N center dot center dot center dot O distance and decrease of the pK and of the changes of Gibbs free energy, of enthalpy and of entropy for the HL1-5 acid dissociation process. The electrochemical behaviour of HL1-5 was interpreted using theoretical calculations at the DFT/HF hybrid level, namely in terms of HOMO and LUMO compositions, and of reactivities induced by anodic and cathodic electron-transfers. Copyright (C) 2010 John Wiley & Sons, Ltd.

Effect of Chemical Pretreatments on the Physical Properties of Kiwi

In this work the effect of pre-treatments on the physical properties of fresh kiwi was studied. For that, a set of tests using chemical pretreatments was used, in which the samples were subjected to aqueous solutions of ascorbic acid and potassium metabisulfite at concentrations of 0.25% and 1% (w/v) for periods of 30 and 60 minutes, in order to understand the implications of the treatments in the color and texture of the kiwi as compared to its original properties. The results showed that the kiwi treated with ascorbic acid changed its color very intensively when compared to the fresh product, and this trend was intensified after storage. Contrarily, when potassium metabisulfite was used, the changes in color were quite negligible right after the treatment and even lower after the storage period of 6 days under refrigeration. After the treatments with both solutions, the kiwi texture was drastically changed, diminishing hardness considerably and increasing elasticity for all treatments. The same could be observed after six days of refrigeration.

Bioactive meroditerpenes from Cystoseira abies-marina, collected from the coast of S. Miguel island

3rd Portuguese Meeting on Medicinal Chemistry and 1st Portuguese-Spanish-Brazilian Meeting on Medicinal Chemistry, Aveiro, 28-30 Novembro 2012.

Synthesis of new Fe(II) and Ru(II) eta(5)-monocyclopentadienyl compounds showing significant second order NLO properties

A series of new ruthenium(II) complexes of the general formula [Ru(eta(5)-C5H5)(PP)(L)][PF6] (PP = DPPE or 2PPh(3), L = 4-butoxybenzonitrile or N-(3-cyanophenyl)formamide) and the binuclear iron(II) complex [Fe(eta(5)-C5H5)(PP)(mu-L)(PP)(eta(5)-C5H5)Fe][PF6](2) (L = (E)-2-(3-(4-nitrophenyl)allylidene)malononitrile, that has been also newly synthesized) have been prepared and studied to evaluate their potential in the second harmonic generation property. All the new compounds were fully characterized by NMR, IR and UV-Vis spectroscopies and their electrochemistry behaviour was studied by cyclic voltammetry. Quadratic hyperpolarizabilities (beta) of three of the complexes have been determined by hyper-Rayleigh scattering (HRS) measurements at fundamental wavelength of 1500 nm and the calculated static beta(0) values are found to fall in the range 65-212 x 10(-30) esu. Compound presenting beta(0) = 212 x 10(-30) esu has revealed to be 1.2 times more efficient than urea standard in the second harmonic generation (SHG) property, measured in the solid state by Kurtz powder technique, using a Nd:YAG laser (1064 nm). (C) 2013 Elsevier B.V. All rights reserved.

Optoelectronic properties of a-Si(1-x)C(x)H films grown in hydrogen diluted silane-methane plasma

This work reports on the optoelectronic properties and device application of hydrogenated amorphous silicon carbide (a-Si(1-x)C(x):H) films grown by plasma-enhanced chemical vapour deposition (PECVD). The films with an optical bandgap ranging from about 1.8 to 2.0 eV were deposited in hydrogen diluted silane-methane plasma by varying the radio frequency power. Several n-i-p structures with an intrinsic a-Si(1-x)C(x):H layer of different optical gaps were also fabricated. The optimized devices exhibited a diode ideality factor of 1.4-1.8, and a leakage current of 190-470 pA/cm(2) at -5 V. The density of deep defect states in a-Si(1-x)C(x):H was estimated from the transient dark current measurements and correlated with the optical bandgap and carbon content. Urbach energies for the valence band tail were also determined by analyzing the spectral response within sub-bandgap energy range. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Influence of the pre-treatments on the properties of biodegradable films from bovine hair

The replacement of conventional synthetic films and coatings by biodegradable alternatives reduces the use of non-renewable resources and waste disposal problems. Considering that Portugal is a major producer of leather, and consequently a large producer of related wastes, in this research, bovine hair was tested for the production of biodegradable films directly by thermo-compression, allowing waste valorisation and reduction of environmental pollution. The aim of this study was to determine the influence of the different pre-treatments performed by two processes (removal by mechanical action and removal by chemical process), applied to bovine hair, in order to obtain a biodegradable film with appropriate properties. Mechanical properties for these films were evaluated, namely strain at break, stress at break and Young modulus. Additionally colour, solubility and swelling in water were also studied. The mechanical removal hair only produced films with Na2S treatment. Chemical removed hair (immunization) depends of the pre-treatment and the degreasing with petroleum ether or sodium sulphide pre-treatment leads better mechanical properties. The results obtained indicated that the pre-treatments have an important role in the final properties of biodegradable films.

Desenvolvimento de tecnologias de extração e de quantificação dos principais componentes nutricionais de macroalgas do litoral dos Açores tendo em vista o seu aproveitamento como suplemento alimentar

Dissertação de Mestrado em Tecnologia e Segurança Alimentar

Evaluation of solubility and partition properties of ampicillin-based ionic liquids

In order to overcome the problems associated with low water solubility, and consequently low bioavailability of active pharmaceutical ingredients (APIs), herein we explore a modular ionic liquid synthetic strategy for improved APIs. Ionic liquids containing l-ampicillin as active pharmaceutical ingredient anion were prepared using the methodology developed in our previous work, using organic cations selected from substituted ammonium, phosphonium, pyridinium and methylimidazolium salts, with the intent of enhancing the solubility and bioavailability of l-ampicillin forms. In order to evaluate important properties of the synthesized API-ILs, the water solubility at 25 °C and 37 °C (body temperature) as well as octanol–water partition coefficients (Kow's) and HDPC micelles partition at 25 °C were measured. Critical micelle concentrations (CMC's) in water at 25 °C and 37 °C of the pharmaceutical ionic liquids bearing cations with surfactant properties were also determined from ionic conductivity measurements.

Valorização de subprodutos da vinha e do vinho: impacto do tempo e métodos de preservação nas suas características

Os polifenóis constituem um grupo biologicamente relevante de compostos naturais, que têm gerado um crescente interesse por parte dos consumidores e das indústrias alimentar, farmacêutica e de cosméticos. Os compostos fenólicos exibem uma vasta gama de propriedades fisiológicas, tais como anti-alérgica, anti-aterogénica, anti-inflamatória, anti-microbiana, antioxidante, anti-trombótica, possuindo efeitos cardio-protetores e vasodilatadores. Por conseguinte, o interesse na obtenção deste compostos ativos de uma forma fácil, barata e rápida tem vindo a aumentar. Uma das fontes de polifenóis são os subprodutos agrícolas, tais como os produtos derivados do vinho e/ou processamento de uvas. As folhas, os caules e os resíduos obtidos durante o processo de produção do vinho têm sido subutilizados, apesar de representarem uma boa fonte de compostos antioxidantes e bioativos. Portugal é um dos mais importantes países produtores de vinho, onde todos os anos são geradas várias toneladas de subprodutos associados a esta indústria. A extração, caracterização, quantificação e avaliação da atividade antioxidante de compostos bioativos extraídos destes subprodutos são, pois, tarefas importantes a fim de avaliar o potencial de utilização destes produtos como novas fontes de compostos antioxidantes. O objetivo deste trabalho foi quantificar e avaliar os teores de polifenóis de extratos preparados a partir de folhas e caules de videira, e bagaço, engaço e grainha de uva. Os parâmetros experimentais da extração foram otimizados, incluindo a proporção de solvente de extração (água/etanol), a temperatura e o tempo de extração. A quantificação dos polifenóis (como fenóis totais e flavonoides) foi efetuada por espetrofotometria de UV/Vis. Verificou-se que a melhor razão de solventes extratores foi de 50/50 (v/v) em água/etanol para todos os subprodutos estudados. No caso dos subprodutos folhas e caules, as condições ideais de extração foram obtidas quando se usou uma temperatura de 40ºC e um tempo de extração de 30 min. Para o bagaço, a temperatura ideal foi de 55ºC durante 5 min. Para o engaço e grainha a utilização de uma temperatura de 40ºC durante 5 min e 30 min, respetivamente, revelou-se o ideal para se obter os compostos. Com este trabalho conclui-se que os subprodutos da vinha e do vinho efetivamente possuem compostos de elevado valor e com capacidade antioxidante.

Síntese sol-gel de biomateriais à base de água de fontes hidrotermais para otimização do comportamento celular e regeneração dos tecidos ósseos

Dissertação de Mestrado, Ciências Biomédicas, 18 de Março de 2016, Universidade dos Açores.

Cultural adaptation and psychometric properties of Brazilian Need for Recovery Scale

OBJECTIVE: To translate the Need for Recovery Scale (NFR) into Brazilian Portuguese and culturally adapt it and assess the stability, internal consistency and convergent validity of the Brazilian scale among industrial workers. METHODS: The translation process followed the guidelines for cultural adaptation of questionnaires including the steps of translation, synthesis, back translation, expert committee review, and pre-testing. The Brazilian Portuguese NFR, final version (Br-NFR) was assessed for stability (n=52) and internal consistency (n=192) and for convergent validity through simultaneous assessment with other instruments: the Borg Scale (n=59); the Chalder Fatigue Questionnaire (n=57) and 3 subscales of the SF-36 (n=56). RESULTS: Stability and internal consistency met the criterion for a reliable measure (ICC=0.80 and Cronbach's alpha =0.87, respectively). The convergent validity between Br-NFR and other instruments also showed good results: Borg Scale (r= 0.64); Chalder Questionnaire (r= 0.67); SF-36 subscales: vitality (r= -0.84), physical functioning (r= -0.54), and role-physical (r= -0.47). CONCLUSIONS: The Br-NFR proved to be a reliable instrument to evaluate work-related fatigue symptoms in industrial workers. Furthermore, it showed significant and good correlations with well-established instruments such as the Borg Scale, the Chalder Questionnaire and SF-36 vitality subscale, supporting the validity of the Br-NFR.

Synthesis and properties of Co-doped titanate nanotubes and their optical sensitization with methylene blue

Agência Financiadora - Fundação para a Ciência e Tecnologia - PTDC/CTM NAN/113021/2009

Preservation of catechin antioxidant properties loaded in carbohydrate nanoparticles

Epigallocatechin gallate (EGCG), an antioxidant with several pharmacological and biological activities, was encapsulated in carbohydrate particles to preserve its antioxidant properties and improve its bioavailability. Gum arabic–maltodextrin particles loaded with EGCG (EGCG/P) were successfully produced by homogenization and spray-drying, with an EGCG loading efficiency of 96 ± 3%. Spray-dried particles are spherical or corrugated and polydisperse with diameters less than 20 m. The particles in aqueous suspension revealed two main populations, with mean average diameters of 40 nm and 400 nm. Attenuated total reflection-infrared spectroscopy (ATR-IR) confirmed that EGCG was incorporated in the carbohydrate matrix by intermolecular interactions, maintaining its chemical integrity. Atomic force microscopy imaging proved the particle spherical shape and size. The present study demonstrates that the carbohydrate matrix is able to preserve EGCG antioxidant properties, as proof of concept to be used as polymeric drug carrier.

Accounting for the dissociating properties of organic chemicals in LCIA: an uncertainty analysis applied to micropollutants in the assessment of freshwater ecotoxicity

In life cycle impact assessment (LCIA) models, the sorption of the ionic fraction of dissociating organic chemicals is not adequately modeled because conventional non-polar partitioning models are applied. Therefore, high uncertainties are expected when modeling the mobility, as well as the bioavailability for uptake by exposed biota and degradation, of dissociating organic chemicals. Alternative regressions that account for the ionized fraction of a molecule to estimate fate parameters were applied to the USEtox model. The most sensitive model parameters in the estimation of ecotoxicological characterization factors (CFs) of micropollutants were evaluated by Monte Carlo analysis in both the default USEtox model and the alternative approach. Negligible differences of CFs values and 95% confidence limits between the two approaches were estimated for direct emissions to the freshwater compartment; however the default USEtox model overestimates CFs and the 95% confidence limits of basic compounds up to three orders and four orders of magnitude, respectively, relatively to the alternative approach for emissions to the agricultural soil compartment. For three emission scenarios, LCIA results show that the default USEtox model overestimates freshwater ecotoxicity impacts for the emission scenarios to agricultural soil by one order of magnitude, and larger confidence limits were estimated, relatively to the alternative approach.

Angolan cymbopogon citratus used for therapeutic benefits: nutritional composition and influence of solvents in phytochemicals content and antioxidant activity of leaf extracts

Folk medicine is a relevant and effective part of indigenous healthcare systems which are, in practice, totally dependent on traditional healers. An outstanding coincidence between indigenous medicinal plant uses and scientifically proved pharmacological properties of several phytochemicals has been observed along the years. This work focused on the leaves of a medicinal plant traditionally used for therapeutic benefits (Angolan Cymbopogon citratus), in order to evaluate their nutritional value. The bioactive phytochemical composition and antioxidant activity of leaf extracts prepared with different solvents (water, methanol and ethanol) were also evaluated. The plant leaves contained ~60% of carbohydrates, protein (~20%), fat (~5%), ash (~4%) and moisture (~9%). The phytochemicals screening revealed the presence of tannins, flavonoids, and terpenoids in all extracts. Methanolic extracts also contained alkaloids and steroids. Several methods were used to evaluate total antioxidant capacity of the different extracts (DPPH; NO; and H2O2 scavenging assays, reducing power, and FRAP). Ethanolic extracts presented a significantly higher antioxidant activity (p < 0.05) except for FRAP, in which the best results were achieved by the aqueous extracts. Methanolic extracts showed the lowest radical scavenging activities for both DPPH; and NO; radicals.