Rural engineering infrastructures design and public facility locations

O desenvolvimento das redes de estradas rurais, especialmente em áreas montanhosas, é a intervenção chave para melhorar a acessibilidade às localidades e aos serviços públicos, cobrindo o maior número de localidades e de serviços públicos, otimizando os escassos recursos disponíveis em países em desenvolvimento. Este estudo explora diferentes modelos de organização de redes de estradas rurais considerando a construção de novas ligações ou o melhoramento de estradas existentes. Um método, baseado na cobertura da rede de estradas rurais, é utilizado para identificar os pontos nodais que formam a rede rural base numa específica região, a qual cobrirá um conjunto dos serviços públicos e de localidades. O modelo assenta numa rede rural de estradas típica ("backbone" e "branch") das regiões montanhosas do Nepal. Os modelos propostos fornecem um conjunto de possibilidades de ligações a estabelecer ou a melhorar e oferece soluções para diferentes níveis de orçamento, que otimizam os custos de transporte na rede, considerando diferentes tipos de pavimento (em solo, granular ou asfáltico). Foi realizado separadamente um modelo dedicado a análises multi-objetivo para resolver problemas de melhoramento de ligações dentro da rede considerando dois objectivos, minimizar os custos de operação para o utilizador e maximizar a população coberta pela rede de estradas, considerando ligações pavimentadas e não pavimentadas (em solo, granular ou asfáltico) dentro de um determinado limite orçamental. O modelo dá ao decisor (DM) diferentes alternativas eficientes para que este possa tomar uma decisão final. Estes modelos, desenvolvidos para redes de estradas rurais, são também aplicáveis a outras redes de infraestruturas rurais, tais como, de fornecimento de água, de eletricidade e de telecomunicações. A implementação dos modelos nas redes de estradas rurais dos distritos de Gorkha e Lamjung do Nepal permitiu confirmara sua aplicabilidade. Verifica-se que os modelos propostos são mais práticos e realísticos no estudo de soluções de melhoramento e de desenvolvimento de redes de estradas rurais em regiões montanhosas de países em desenvolvimento.

Development of lithium disilicate based glass-ceramics

O principal objectivo deste estudo foi o desenvolvimento de vitrocerâmicos à base de dissilicato de lítio no sistema Li2O-K2O-Al2O3-SiO2 contendo uma razão molar SiO2/Li2O muito afastada da do dissilicato de lítio (Li2Si2O5) usando composições simples e a técnica tradicional de fusão-vazamento de vidro de forma a obter materiais com propriedades mecânicas, térmicas, químicas e eléctricas superiores que permitam a utilização destes materiais em diversas aplicações funcionais. Investigou-se o fenómeno de separação de fases, a cristalização e as relações estrutura-propriedades de vidros nos sistemas Li2O-SiO2, Li2O-Al2O3-SiO2 e Li2O-K2O-Al2O3-SiO2. Os vidros nos sistemas Li2O-SiO2 e Li2O-Al2O3-SiO2 apresentaram fraca densificação e resultaram em materiais frágeis, contrastando com a boa sinterização dos vidros no sistema Li2O-K2O-Al2O3-SiO2. Pequenas adições de Al2O3 e K2O ao sistema Li2O-SiO2 permitiram controlar a separação de fases devido à formação de espécies de Al(IV) que confirmaram o papel de Al2O3 como formador de rede. Os compactos de pó de vidro das composições contendo Al2O3 e K2O tratados termicamente resultaram em vitrocerâmicos bem densificados, apresentando dissilicato de lítio como a principal fase cristalina, e valores de resistência mecânica à flexão, resistência química e condutividade eléctrica (173-224 MPa, 25-50 mg/cm2 e ~2´10-18 S/cm, respectivamente) que possibilitam a utilização destes materiais em diversas aplicações funcionais. A adição de P2O5, TiO2 e ZrO2 ao sistema Li2O-K2O-Al2O3-SiO2 como agentes nucleantes revelou que os vidros contendo apresentaram cristalização em volume, com a formação de metassilicato de lítio a temperaturas mais baixas e dissilicato de lítio para as temperaturas mais elevadas, enquanto a adição de zircónia reduz o grau de segregação, aumenta a polimerização da matriz vítrea e desloca o valor de Tg para temperaturas superiores, inibindo a cristalização.

Volatile terpenoids and C13 norisoprenoids in wines: development of rapid methods of analysis and evaluation of the sesquiterpenoids biological potential

Vitis vinifera L., the most widely cultivated fruit crop in the world, was the starting point for the development of this PhD thesis. This subject was exploited following on two actual trends: i) the development of rapid, simple, and high sensitive methodologies with minimal sample handling; and ii) the valuation of natural products as a source of compounds with potential health benefits. The target group of compounds under study were the volatile terpenoids (mono and sesquiterpenoids) and C13 norisoprenoids, since they may present biological impact, either from the sensorial point of view, as regards to the wine aroma, or by the beneficial properties for the human health. Two novel methodologies for quantification of C13 norisoprenoids in wines were developed. The first methodology, a rapid method, was based on the headspace solid-phase microextraction combined with gas chromatography-quadrupole mass spectrometry operating at selected ion monitoring mode (HS-SPME/GC-qMS-SIM), using GC conditions that allowed obtaining a C13 norisoprenoid volatile signature. It does not require any pre-treatment of the sample, and the C13 norisoprenoid composition of the wine was evaluated based on the chromatographic profile and specific m/z fragments, without complete chromatographic separation of its components. The second methodology, used as reference method, was based on the HS-SPME/GC-qMS-SIM, allowing the GC conditions for an adequate chromatographic resolution of wine components. For quantification purposes, external calibration curves were constructed with β-ionone, with regression coefficient (r2) of 0.9968 (RSD 12.51 %) and 0.9940 (RSD of 1.08 %) for the rapid method and for the reference method, respectively. Low detection limits (1.57 and 1.10 μg L-1) were observed. These methodologies were applied to seventeen white and red table wines. Two vitispirane isomers (158-1529 L-1) and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) (6.42-39.45 μg L-1) were quantified. The data obtained for vitispirane isomers and TDN using the two methods were highly correlated (r2 of 0.9756 and 0.9630, respectively). A rapid methodology for the establishment of the varietal volatile profile of Vitis vinifera L. cv. 'Fernão-Pires' (FP) white wines by headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (HS-SPME/GCxGC-TOFMS) was developed. Monovarietal wines from different harvests, Appellations, and producers were analysed. The study was focused on the volatiles that seem to be significant to the varietal character, such as mono and sesquiterpenic compounds, and C13 norisoprenoids. Two-dimensional chromatographic spaces containing the varietal compounds using the m/z fragments 93, 121, 161, 175 and 204 were established as follows: 1tR = 255-575 s, 2tR = 0,424-1,840 s, for monoterpenoids, 1tR = 555-685 s, 2tR = 0,528-0,856 s, for C13 norisoprenoids, and 1tR = 695-950 s, 2tR = 0,520-0,960 s, for sesquiterpenic compounds. For the three chemical groups under study, from a total of 170 compounds, 45 were determined in all wines, allowing defining the "varietal volatile profile" of FP wine. Among these compounds, 15 were detected for the first time in FP wines. This study proposes a HS-SPME/GCxGC-TOFMS based methodology combined with classification-reference sample to be used for rapid assessment of varietal volatile profile of wines. This approach is very useful to eliminate the majority of the non-terpenic and non-C13 norisoprenic compounds, allowing the definition of a two-dimensional chromatographic space containing these compounds, simplifying the data compared to the original data, and reducing the time of analysis. The presence of sesquiterpenic compounds in Vitis vinifera L. related products, to which are assigned several biological properties, prompted us to investigate the antioxidant, antiproliferative and hepatoprotective activities of some sesquiterpenic compounds. Firstly, the antiradical capacity of trans,trans-farnesol, cis-nerolidol, α-humulene and guaiazulene was evaluated using chemical (DPPH• and hydroxyl radicals) and biological (Caco-2 cells) models. Guaiazulene (IC50= 0.73 mM) was the sesquiterpene with higher scavenger capacity against DPPH•, while trans,trans-farnesol (IC50= 1.81 mM) and cis-nerolidol (IC50= 1.48 mM) were more active towards hydroxyl radicals. All compounds, with the exception of α-humulene, at non-cytotoxic levels (≤ 1 mM), were able to protect Caco-2 cells from oxidative stress induced by tert-butyl hydroperoxide. The activity of the compounds under study was also evaluated as antiproliferative agents. Guaiazulene and cis-nerolidol were able to more effectively arrest the cell cycle in the S-phase than trans,trans-farnesol and α-humulene, being the last almost inactive. The relative hepatoprotection effect of fifteen sesquiterpenic compounds, presenting different chemical structures and commonly found in plants and plant-derived foods and beverages, was assessed. Endogenous lipid peroxidation and induced lipid peroxidation with tert-butyl hydroperoxide were evaluated in liver homogenates from Wistar rats. With the exception of α-humulene, all the sesquiterpenic compounds under study (1 mM) were effective in reducing the malonaldehyde levels in both endogenous and induced lipid peroxidation up to 35% and 70%, respectively. The developed 3D-QSAR models, relating the hepatoprotection activity with molecular properties, showed good fit (R2LOO > 0.819) with good prediction power (Q2 > 0.950 and SDEP < 2%) for both models. A network of effects associated with structural and chemical features of sesquiterpenic compounds such as shape, branching, symmetry, and presence of electronegative fragments, can modulate the hepatoprotective activity observed for these compounds. In conclusion, this study allowed the development of rapid and in-depth methods for the assessment of varietal volatile compounds that might have a positive impact on sensorial and health attributes related to Vitis vinifera L. These approaches can be extended to the analysis of other related food matrices, including grapes and musts, among others. In addition, the results of in vitro assays open a perspective for the promising use of the sesquiterpenic compounds, with similar chemical structures such as those studied in the present work, as antioxidants, hepatoprotective and antiproliferative agents, which meets the current challenges related to diseases of modern civilization.